WO2009089105A1

WO2009089105A1 - Flexible display

Info

Publication number: WO2009089105A1
Application number: PCT/US2009/030040
Authority: WO
Inventors: Richard C. Cope; Guo Liu; Aris K. Silzars; Gary E. Thomas; Drew F. Meincke
Original assignee: Nanolumens
Priority date: 2008-01-04
Filing date: 2009-01-02
Publication date: 2009-07-16

Abstract

A flexible display includes a plurality of pixel chips, chixels, provided on a flexible substrate. The chixels and the light emitters thereon may be shaped, sized and arranged to minimize chixel, pixel, and subpixel gaps and to provide a desired bend radius of the display. The flexible substrate may include light manipulators, such as filters, light convertors and the like to manipulate the light emitted from light emitters of the chixels. The light manipulators may be arranged to minimize chixel gaps between adjacent chixels.

Description

FLEXIBLE DISPLAY

FIELD OF INVENTION

The present invention relates to display devices. More particularly, the present invention comprises a flexible display.

BACKGROUND

There has been increased interest in the development of flexible displays. It has proven difficult, however, to produce a large flexible display, as manufacturing techniques used to produce small-scale displays have not proven readily scalable. Presently, large scale displays tend to be heavy, expensive, non-flexible, unreliable and power hungry.

A liquid crystal display (LCD) is an electro-optical amplitude modulator realized as a thin, flat display device made up of any number of color or monochrome pixels arrayed in front of a light source or reflector, called the backlight. It is often utilized in battery-powered electronic devices because it uses very small amounts of electric power.

Each pixel of an LCD typically consists of a layer of molecules aligned between two transparent electrodes, two pieces of glass, and two polarizing filters. The axes of transmission of the polarizing filters are typically perpendicular to each other. The surfaces of the glass that are in contact with the liquid crystal material are treated with a polymer to create unidirectional grooves. When the liquid crystal is applied, the molecules are aligned in the direction of the grooves. Electrodes are typically made of a transparent conductor called Indium Tin Oxide (ITO), but other transparent conductors may be used.

When a voltage is applied across the electrodes, a torque acts to align the liquid crystal molecules parallel to the electric field, distorting the helical structure (this is resisted by elastic forces since the molecules are constrained at the surfaces). This reduces the rotation of the polarization of the incident light, and the device appears gray. If the applied voltage is large enough, the liquid crystal molecules in the center of the layer are almost completely untwisted and the polarization of the incident light is not rotated as it passes through the liquid crystal layer. This light will then be mainly polarized perpendicular to the second filter, and thus be blocked and the pixel will appear black. By controlling the voltage applied across the liquid crystal layer in each pixel, light can be allowed to pass through in varying amounts thus constituting different levels of gray.

As light strikes the first filter, it is polarized. The molecules in each layer then guide the light they receive to the next layer. As the light passes through the liquid crystal layers, the molecules also change the light's plane of vibration to match their own angle. When the light reaches the far side of the liquid crystal substance, it vibrates at the same angle as the final layer of molecules. If the final layer is matched up with the second polarized glass filter, then the light will pass through.

When a large number of pixels are needed in a display, it is not technically possible to drive each directly since then each pixel would require independent electrodes. Instead, the display is multiplexed; electrodes on one side of the display are grouped and wired together

(typically in columns), and each group gets its own voltage source. On the other side, the electrodes are also grouped (typically in rows), with each group getting a voltage sink. The groups are designed so each pixel has a unique, unshared combination of source and sink. The drive electronics, then turns on sinks in sequence, and drives sources for the pixels of each sink.

In color LCDs each individual pixel is divided into three cells, or subpixels, which are colored red, green, and blue, respectively, by additional filters (pigment filters, dye filters and metal oxide filters). Each subpixel can be controlled independently to yield thousands or millions of possible colors for each pixel.

High-resolution color displays such as modern LCD computer monitors and televisions use an active matrix structure. A matrix of thin-film transistors (TFTs) is added to the polarizing and color filters such that each pixel has its own dedicated transistor. In this arrangement, when a row conductor is activated, all of the column conductors are driven at the correct voltage. Then the row conductor is deactivated, and the next row conductor is activated. All of the row conductors are activated in sequence during a refresh operation.

SUMMARY OF THE INVENTION

In one exemplary embodiment, a flexible display includes a plurality of self-contained pixel-containing chips, called chixels, that are arranged on a flexible substrate in a manner that provides sufficient bend radius to the substrate to allow flexing of the display. The chixels may include a sub-array of pixels provided on a rigid substrate that may be sealed to form a modular unit. A chixel can be combined with other chixels on a flexible substrate so that multiple pixel sub-arrays combine to form a large pixel array for a display. The chixels may be rigid units of a predetermined size and shape and arranged on the display substrate in a manner to provide a desired bend radius to the substrate and produce a display having a desired degree of flexibility.

The flexibility of the chixel display is a function of the bend gaps between the chixels. As used herein the term "bend gap" refers to the space between adjacent chixels. Generally, the smaller the chixels, the greater number of bend gaps and the more flexible the display. A chixel may be formed in a particular shape and arranged on a flexible substrate in such a way as to provide a chixel-based display of a desired flexibility. For example, a chixel may be square- shaped and have an n x n pixel arrangement, such as a 4 x 4 arrangement, to allow similar flexibility in both the horizontal and vertical planes. To increase flexibility in one particular plane more than another, the size of the chixel in that particular plane may be decreased to provide more bending points. For example, a pixel arrangement including elongated rectangular-shaped chixels having a 4-row X 8-column pixel arrangement thereon may provide twice as many vertical gaps as horizontal gaps and thereby provide greater lateral flexibility. Furthermore, chixels of different sizes or shapes may be incorporated into a display to customize the flexibility of different portions of the display.

In an exemplary embodiment of a chixel, a plurality of light emitters is provided on a rigid substrate and serves as subpixels of a display. The subpixels may be divided into groupings, such as groupings of three subpixels, to form pixels. For example, subpixels that emit red, green and blue light may be grouped together to form an RGB pixel. Other arrangements, such as by way of example and not limitation, include a monocolor display in which all subpixels or pixels emit the same color light. Additionally, the light emitted by the pixels or subpixels may be converted or filtered to provide the desired light output; for example, the pixels could be formed of blue LEDs that are filtered or are color converted and filtered. The subpixels may be of rectangular shape so that when combined with other subpixels they form a square pixel. For example, each subpixel may be of a size l/3x X x, so that three subpixels placed side-by -side form a square pixel of size x X x. The pixels may be arranged on the substrate such that the space between adjacent pixels, referred to herein as a "pixel gap," is of a desired distance dl. Because there are no pixels to produce light at the pixel gap, the gap may appear as a darkened area of a display, referred to as a "pixel gap line." Similarly, the subpixels may be uniformly spaced so that space between subpixels, the "subpixel gap", is of a desired size. In one aspect of the invention, the pixels are of a size relative to the pixel gap to make the pixel gap line less noticeable to a viewer. For example, the pixels may be of a size relative to the size of the pixel gap so as to provide a display of a desired resolution in which the pixel gap is not as pronounced or distracting to the viewer. This relationship and sizing may depend on a number of factors, including, but not limited to, viewing distance, contrast ratio, brightness, and viewing environment.

As mentioned above, the chixels are provided on the flexible display substrate adjacent other chixels. The distance between the chixels is referred to herein as a "chixel gap." In an exemplary embodiment the chixels are arranged so that the chixel gap in minimized and the "pixel gap" between adjacent pixels is uniform throughout the display, even across adjacent chixels. In another exemplary embodiment the subpixel gaps are uniform within a chixel as well as between adjacent chixels.

The subpixels and pixels of the chixels may comprise various light emitters. In one exemplary embodiment, a chixel comprises subpixels and pixels formed of light emitted diodes (LEDs). In an exemplary method of making an LED-based chixel, a plurality of LEDs is prepared on a rigid substrate. For example, an n-doped layer and a p-doped layer are provided on a rigid substrate, such as glass or sapphire wafer to form LED layers. Various layers may be used in the LED manufacturing process to produce LEDs which emit light with desired properties. For example, various phosphor layers may be used to produce light of desired wavelengths and color. These layers may be provided to the bottom of the substrate. For example, a photoconversion layer may be provided on the bottom of the rigid substrate to convert blue emitted light into white light which is more efficiently filtered to different colors. In one exemplary embodiment of the invention, a light manipulator may be added. For example, filters made of coextruded polycarbonate plastics, surface coated plastics, or deep dyed polyesters may be provided to convert the light emitted from the LEDs to a light with desired characteristics. For example, most filters are subtractive, allowing only a portion of the emitted light to pass through the filter. For example, filters and color conversion techniques may be used to provide light of desired properties. For example, filters may be used to produce red and green light from emitted blue light. The dyes for the filters may be optimized to produce the desired wavelength of light output from the light emitted from the LED. A color conversion phosphor may be deposited over the blue LEDs to produce a white light emission that may then be filtered into desired colors, such as red, blue, and green. The filter film could be provided to the chixel or to the flexible substrate to which the chixels are attached.

Portions of the LED layers may then be removed by etching or other known techniques to form a plurality of spaced-apart LED stacks that share the same substrate. For example, portions of the LED layers could be removed down to the rigid substrate so as to provide LED stacks that share the same substrate. The particular size of the LED stacks can vary according to the use to the use of the display. For example, for displays meant for close viewing the LEDs can be etched into smaller stacks than displays meant for viewing at greater distances.

Contacts may then be provided to the LED stacks to form a plurality of spaced apart LEDs on a rigid substrate that together form an LED wafer. The LEDs may be provided with rear contacts so that rear display drivers may be used to drive the display in which the chixels are incorporated. For example, a portion of the p-doped layer of the LED stack may be removed expose the n-doped layer in order to provide an n-contact area at the top end of the LED stack. This allows for conductor wires to the contact to extend upwardly from the display and diminishes the need for space between LEDs for the contact. A p-contact may also be provided at the top of the stack to form a rear-drivable LED.

The LED wafer may then be subdivided into smaller portions that define chixels, each chixel having a plurality of LEDs that will serve as sub-pixels, The chixels can then be placed on a flexible substrate in an arrangement that allows bending between the chixels and provided with drive means to form a flexible display. This manufacturing process allows for accurate spacing between the LEDs by using masking, etching or other known techniques that produce uniformly spaced subpixels. Furthermore, the process allows for the accurate arrangement of subpixels between chixels and, therefore, uniform subpixel placement throughout a display as well as minimal subpixel, pixel, and chixel gaps.

Traditionally an LED wafer is diced into individual LEDs that are then housed in separated LED assemblies. These separate LED assemblies are then incorporated into a display as individual subpixels. Due to the individual housings of the LEDs, however, that method results in displays with non-uniform subpixel or pixel spacing and large subpixel gaps and pixel gaps. Furthermore, each individual LED must be provided separately into the display, resulting in a large number of manufacturing operations.

Chixels may be formed by halting an LED wafer production process before the substrate is diced to form discrete LEDs. In a typical process for producing blue emitting LEDs, a layer of p-doped gallium nitride is deposited on a 2" sapphire wafer. Then, a layer of n-doped gallium nitride is deposited. A photomask is deposited and the gallium nitride layers are selectively photoetched to create individual LED units and their respective electrodes. In the manufacture of discrete LEDs, the wafer would then be diced, and the LEDs would be packaged. In the chixel production process, the wafer is diced, but instead of discrete LEDs, the dicing is performed so that the resulting diced pieces hold x X x arrays of LEDs.

Under an exemplary method of the present invention, multiple LEDs share a single LED substrate by cutting the LED wafer into larger units, chixels, that comprise a plurality of LEDs that define subpixels and together form pixels of a display. This allows for uniform spacing between the LEDs, and therefore uniform spacing between subpixels and pixels and results in smaller subpixel and pixel gaps. By manufacturing the LEDs on the same rigid wafer substrate, the pitch of the LEDs can be tightly controlled during the LED wafer manufacturing process using masking, etching and other techniques thereby providing a uniform subpixel and pixel pitch. The LEDs may be provided with contacts and a drive means to form workable subpixels of a display. Furthermore, the exemplary method allows for different chixel sizes and shapes to be selected during the dicing process and is easily adjustable to different subpixel sizes by changing the etching process. For example, an LED wafer may be grown having LEDs of a size 320 microns square and separated by 320 microns on each side and then separated into sub-units of 96 LEDs, each LED corresponding to a subpixel of a display. For example, the 96 LEDs may correspond to 8 rows of 12 subpixels. The subpixels may be grouped into three to define pixels to form a 4 X 8 pixel arrangement. Or the LED wafer may be divided into chixels having 48 LED subpixels to form a 4 X 4 pixel arrangement. The subpixel size can be changed by simply using a different etching mask and the chixel size by changing the dicing cut lines. A plurality of chixels, having a plurality of light emitters, which will serve as subpixels of a display, may be arranged on a flexible substrate to produce a flexible display. In one exemplary method the chixels are placed light-emitting end down onto a flexible substrate so as to transmit light through the flexible substrate. The chixels may be arranged at a predetermined spacing to produce a desired chixel gap to provide a desired bend radius to the flexible substrate. Drive means may be provided to the chixels to power the light emitters for emitting light. The drive means may include a controller to control the light emitted from each light emitter (subpixel) to produce a desired image on the display. In one exemplary embodiment a controller is provided for each chixel to produce a chixel-partitioned display. This has the advantage of decreasing the number and length of wires and distributes the size of the controller unit out among the chixels, possibly reducing the bulk of the display electronics by subdividing them into smaller, though more numerous, units. In one exemplary embodiment a flexible substrate that may be used in conjunction with the chixels includes a diffusion layer, a contrast enhancement layer, and a hardened outer layer. The chixels may be attached to the flexible substrate by an adhesive or other means so that light emitted from the chixel is transmitted through the flexible substrate. The flexible substrate may also include one or more filters to manipulate the light emitted from the LEDs. For example, the substrate may include an arrangement of red, green and blue filters that correspond to the location of light emitters of the chixels to provide red, green and blue subpixels of the display.

It is possible to produce an RGB display using monocolor LEDs and either filters or color conversion and filters. Both techniques use blue (gallium nitride, GaN) LEDs. In the first embodiment, blue LEDs may be filtered to allow only red or green wavelengths of light to be emitted. In this case, the blue would not be further filtered for blue light emission unless it was desirable to emit a different color point. In the second embodiment, a white color conversion phosphor is deposited over the blue LEDs. This results in white light emission that can then be filtered into red, green and blue. The filtering of white to RGB is more efficient than the filtering of blue to red or green. The filters used in these embodiments could be provided in the form of a flexible film onto which the appropriate dyes and/or filter materials have been printed in the desired pattern. An example of this type of film is that used on backlit LCD laptop monitors. In an effort to make the chixel gap less noticeable to the viewer, the filter film area corresponding to the edge of a chixel may be printed with the pixel shape rotated 90°, and LEDs from both adjacent chixels will light the rotated pixel.

In one exemplary embodiment, in which blue LEDs are used, red and green filters may be provided to make RGB pixels. As discussed above, the LEDs of the chixel may include a photoconversion layer so that the LEDs emit white light, in which case red, green, and blue filters may be used. Arrangements other than standard RGB pattern may be used. For example, in one exemplary embodiment, filters are arranged to minimize the subpixel, pixel, and chixel gap by providing filters that bridge two adjacent chixels. For example, a red filter may be placed so as to cover subpixels from two different chixels. Furthermore, although discussed as one light emitter to one subpixel, multiple light emitters may be used for one subpixel. For example, each colored filter may include three LEDs.

In other embodiments, the chixels comprise other light emitters. In one exemplary embodiment, a chixel comprises subpixels and pixels formed of liquid crystal display (LCDs). In another exemplary embodiment, a chixel comprises subpixels and pixels formed of organic LEDs (OLEDs).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a flexible display in accordance with an exemplary embodiment of the invention. FIG. 2 shows an enlarged view of a portion of the display of FIG. 1 along cut line 2-2.

FIGS 3A-3B show a side view of a flexible chixel display in accordance with an exemplary embodiment of the invention.

FIG. 4 shows a chixel in accordance with an exemplary embodiment of the invention.

FIG. 5 shows a flexible display which incorporates square-shaped chixels in accordance with an exemplary embodiment of the invention.

FIG. 6 shows a flexible display which incorporates square-shaped chixels of FIG. 5.

FIG. 7 shows an elongated chixel in accordance with an exemplary embodiment of the invention.

FIG. 8 shows a flexible display incorporating the elongated chixels of FIG. 7. FIG. 9 shows a chixel-based display in accordance with an exemplary embodiment of the invention.

FIG. 10 shows an enlarged portion of the chixel-based arrangement of FIG. 9.

FIG. 11 shows an LED wafer in accordance with an exemplary embodiment of the invention. FIG. 12 shows a side view of the wafer of FIG. 11. FIG. 13 shows an LED stack of the wafer of FIG. 11.

FIG. 14 shows a side view of an LED of a chixel in accordance with an exemplary embodiment of the invention. FIG. 15 shows a top view of the LED of FIG. 14.

FIG. 16 shows a white light emitting LED of a chixel in accordance with an exemplary embodiment of the invention.

FIG. 17 shows an alternative embodiment of a chixel LED.

FlG. 18A shows a top view of an LED wafer in accordance with an exemplary embodiment of the invention.

FIG. 18B shows an enlarged portion of the LED wafer of FIG. 18A.

FIG. 19 shows a chixel separated from the LED wafer of FIG. 18A in accordance with an exemplary embodiment of the invention.

FIG. 20 shows the chixel of FIG. 19 incorporated into a display. FIG. 21 sows an enlarged portion of the display of FIG. 20.

FIG. 22 shows a display substrate in accordance with an exemplary embodiment of the invention.

FIG. 23 shows a side view of a chixel-based display.

FIG. 24 shows a flexible chixel-based display in accordance with an exemplary embodiment of the invention.

FIG. 25 shows a flexible chixel-based display having dedicated controllers for each chixel.

FIG. 26 shows a chixel and filter arrangement for a chixel-based display in accordance with an exemplary embodiment of the invention. FIG. 27 a chixel-based display incorporating the chixel and filter of FIG. 26.

FIG. 28 shows an exemplary embodiment of a chixel having additional edge light emitters. FIG. 29 shows a color flexible chixel-based display incorporating the chixel of FIG. 28.

FIG. 30 shows an enlarged portion of the display of FIG. 29. FIG. 31 shows an exemplary embodiment of filter pattern. FIG. 32 shows an exemplary chixel and filter arrangement.

FIG. 33 shows an exemplary OLED-containing chixel. FIG. 34 shows an exemplary OLED-containing chixel stackup.

FIG. 35 is a top planar view, illustrating exemplary conductive leads for the OLED- containing chixel stackip of FIG. 34. FIG. 36 is a top planar view, illustrating one or more transparent conductive layers of

FIG. 34.

FIG. 37 shows an exemplary OLED-containing chixel stackup. FIG. 38 illustrates an exemplary chixel arrangement. FIG. 39 illustrates an exemplary row cross-bar connection. FIG. 40 shows an embodiment of the present invention in which two OELDs are used to form a single subpixel,

FIG. 41 shows an embodiment of the present invention in which two OELDs are used to form a single subpixel.

FIG. 42 illustrates an alternate arrangement of a chixel. FIG. 43 illustrates an alternate arrangement of a chixel.

FIGs . 44A-C illustrate an alternate chixel stackup. FIG. 45 illustrates an exemplary embodiment of a chixel stackup. FIG. 46 illustrates an alternate structure for introducing moisture to an OLED stack.

FIG. 47 shows an LCD stack in accordance with exemplary embodiments of the invention.

FIG. 48A-D show LCD stacks in accordance with exemplary embodiments of the invention.

FIG. 49 shows a color filter, according to an exemplary embodiment of the invention. FIG. 50 shows chixels incorporated into a display, according to an exemplary embodiment of the invention.

FIG. 51 shows a display substrate in accordance with an exemplary embodiment of the invention. FIG. 52 shows a flexible chixel-based display, according to an exemplary embodiment of the invention.

FIG. 53 shows a flexible chixel-based display having dedicated controllers for each chixel in accordance with an exemplary embodiment of the invention.

FIG. 54 shows an alternative embodiment of a color filter, according to an exemplary embodiment of the invention.

DETAILED DESCRIPTION

As required, exemplary embodiments of the present invention are disclosed herein. These embodiments are meant to be examples of various ways of implementing the invention and it will be understood that the invention may be embodied in alternative forms. The figures are not to scale and some features may be exaggerated or minimized to show details of particular elements, while related elements may have been eliminated to prevent obscuring novel aspects. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention.

For purposes of teaching and not limitation, the exemplary embodiments disclosed herein are discussed mainly in the context of LED light emitter technologies. However, the present invention is applicable to other light emitting technologies as well, such as, by way of example and not limitation, backlit LCDs, electroluminescence, or plasma tubes or cells. Turning to the figures where like elements have like reference numbers throughout the several views, FIG. 1 shows an exemplary embodiment of a flexible display 100. As shown in FIG. 2, the flexible display 100 is comprised of a plurality of pixel chips 202, referred to herein as chixels 202, that are arranged in a chixel arrangement 200. The chixels 202 may be rigid self-contained components that include a plurality of pixels 204, formed of subpixels 206. The chixels 202 are of a sufficiently small size and attached to a flexible display substrate 208 in such a manner that the space between the chixels, referred to herein as a chixel gap 304, allows the flexible display substrate 208 to have a bending radius to provide a desired flexibility to the display 100.

For example, as shown in FIG. 3A, chixels 202 are provided on a flexible display substrate 208 with a chixel gap 304 of a size so that the side edges of the chixels are parallel when the substrate 208 is flat. As shown in FIG. 3B, as the substrate 208 flexes, the chixels 202 move at angles with respect to one another due to the bending of the substrate 208 at the chixel gaps 304. Although shown as square chixels 202 with sharp upper corners, the chixels 202 could have rounded corners or other shapes to prevent contact between adjacent chixels 202 during bending of the substrate 208. Furthermore, the chixels 202 could be shaped so as to limit or prevent flexing of the substrate in a particular direction. For example, the chixels could have extensions (not shown) that contact each other to limit movement when the display is flexed in a particular direction. The size of the chixels and spacing between the chixels could also be varied to provide desired flexibility. For example, smaller chixels could be used on portions of the display which require more flexibility and larger chixels used on portions with lower flexibility requirements.

The chixels 202 are of a predetermined shape and arranged in a desired pattern on a flexible substrate 208 to form a flexible display 100. The size, shape, and arrangement of the chixels 202 may be selected to provide a desired bend radius to the flexible substrate 208 to which the chixels 202 are incorporated. As shown in an exemplary embodiment in FIG. 4, a chixel 202 may be generally square in shape. For example, the chixel may comprise a 4 X 4 array of 16 pixels 204, each pixel having three subpixels 206. As shown in FIG. 5, this square shape allows a chixel- based display 500 in which the chixels 206 are incorporated to flex easily both horizontally and vertically between the chixels 202 as the ratio of vertical and horizontal chixels gaps 304 is the same. FIG. 6 shows a chixel display having chixels 202 on a flexible substrate with sufficient bend radius to be rolled up into a tube having a radius of approximated by:

Where x = width of a chixel; s = width of space between chixels; and n = number of chixels in the tube; and provided that n > 4, x > 0.5s, and assuming the tube cross-section is circular,

Chixels 202 may be provided in other shapes and arranged to provide a chixel gap 304 of an appropriate size to provide the display 100 with a desired amount of flexibility. Generally, the smaller the chixel 202, the greater the number of chixel gaps 304 in the display in which the chixels are incorporated and the greater the number of bending points that can be provided and, therefore, the greater the flexibility of the display. For example, if it is desirable to provide a greater amount of flexibility in one direction of the substrate than another then the chixels can be shaped to provide such flexibility by arranging a larger number of flexible gaps in the one direction than the other.

The chixel 702 shown in FIG. 7 includes a 4 X 8 pixel arrangement. As shown in FIG. 8, this allows for greater lateral bending because there are approximately twice as many vertical bending points 804 in the display than horizontal bending 806 points. Although the smaller the chixel, the greater the number of chixel gaps and the greater the flexibility of the display, the fewer the number of pixels that can be provided on the chixel and/or the smaller the pixels. Thus, while having smaller chixels increases flexibility, having larger chixels increases the size and/or number of pixels that can be provided on each chixel and decreases the number of chixels that must be attached to the flexible substrate. Thus, smaller chixels could be used in areas of the display with higher flexibility requirements.

As shown in FIG. 4, a chixel 202 may include pixels 204 that are comprised of subpixels 206. The subpixels 206 may have different properties in order to provide desired properties for the pixel 204 of which they form a part. For example, the pixels 204 may comprise red 206A, green 206B, and blue 206C subpixels that together form an RGB pixel. The intensity of the individual subpixels 206A, 206B, 206B can be manipulated to provide light having desired characteristics, such as a desired light color or brightness. The subpixels 206 may have a rectangular shape so that together they form a square-shaped pixel 204. For example, each subpixel may have dimensions of 1/3 mm X 1 mm to form a pixel of 1 mm². The pixels 204 may be provided in a 4 X 4 array on a rigid substrate 220 to form a chixel of about 4 mm². The substrate 220 may be transparent to allow light emission through the substrate. For example, the substrate may be rigid glass or sapphire as discussed in more detail below. The pixels 204 may be provided at a distance apart from one another, the distance referred to as a "pixel gap" 304. The size of the pixel gap 304 may vary depending upon the particular light emitting technology used for the subpixel 206. For example, some light emitters may require conductors that extend around the edge of the emitter, which prevents the light emitters from directly abutting each other, thereby resulting in large subpixel and pixel gaps. For example, Organic Light Emitting Diodes (OLEDS) generally require that current be provided through the front of the display and a contact is commonly arranged to extend around the edge of the OLED, thereby preventing OLEDs from being tightly packed in a display. One problem with prior art displays is that the pixel gap 304 is of such size that gap lines are visible in the resulting display which is distracting to a viewer and renders an image of poorer quality. This led to prior art attempts to provide front conductors for the pixels. This front conductor approach raises additional problems in producing flexible displays, however, due to the limited flexibility and high resistance values of known transparent front electrodes.

In one aspect of the present invention, the pixels 204 are sized relative to the pixel gap 306 between the pixels 204 such that the pixel gap 306 is less noticeable to an observer. For example, in a prior art OLED device the gaps between pixels that are required for the wraparound electrodes can result in a pixel gap to pixel area ratio that is readily noticeable to a viewer of the display.

In the present invention, pixels 204 are sized relative to the pixel gap 306 so that the gap line is less noticeable while still providing a desired resolution. For example, in the exemplary embodiment shown in FIG. 4, the pixel gap d2 may be 0.25mm and the pixel size (width or height) lmm to produce a pixel gap to pixel size ratio of 0.25mm/lmm= 0.25. Applicant has found that for a 120" display at 108Op a pixel size of 1 mm² is desirable. In another exemplary embodiment, the pixel gap d2 may be 0.80mm and the pixel size (width or height) 2.60mm to produce a pixel gap to pixel size ratio of 0.80mm/2.60mm= 0.31.

As discussed in more detail below, minimizing the effect of the gap line allows for the use of manufacturing techniques and resulting structures that were previously avoided due to concerns over gap lines. For example, by adjusting the pixel size to the pixel gap to minimize the effect of a gap line allows for electrodes to extend around the side of a pixel and allow a display to be driven at the rear, thereby eliminating some of the problems with prior art devices that are front driven.

One advantage of the present invention is that if a 4 mm chixel 202 which includes 16 pixels in a 4 X 4 array is used to provide the pixels for the display, the number of operations to provide the pixels 204 to the display is 1/16 of that of a technique that attempts to attach individual pixels to a display because multiple pixels are added with a single chixel. As discussed in more detail below, minimizing the effect of the gap line allows for the use of manufacturing techniques and resulting structures that were previously avoided due to concerns over gap lines. For example, by adjusting the pixel size to the pixel gap to minimize the effect of a gap line allows for electrodes to extend around the side of a pixel and allow a display to be driven at the rear, thereby eliminating some of the problems with prior art devices that are front driven.

As shown in FIG. 9, chixels 202 may be coupled to a flexible display substrate 208 by an adhesive or other coupling means. The pixels 204 can be arranged on the chixel 202 with uniform pixel spacing of a pitch or pixel gap d2. The chixels 202 can be arranged on the flexible display substrate 208, to maintain the uniform pixel gap 304 d2 between adjacent chixels 202A, 202B. For example, the pixels 202 may be located near the edges 91 OA-B of the chixels 202 and adjacent chixels 202A-B arranged so that the pixel gap 306 is uniform between pixels 204 even across adjacent chixels 202A, 202B. As discussed above, the chixel gap 304 between the chixels 202 provides a desired bend radius to the flexible substrate 208 that allows the display 100 to flex. Thus, a uniform pixel gap and a desired flexibility can be obtained; in other words the pixel pitch is consistent in both the rows and columns, even between pixels on the edges of two adjacent chixels. In one exemplary embodiment the pixel gap may be 320 micron, the chixel gap 320 micron and the pixel size 1600 micron. As discussed in more detail below, the flexible substrate 208 may comprise a variety of layers, such as by way of example and not limitation, a contrast layer, a diffusion layer, a filter layer, and an anti-reflection layer. Each of these layers may be of a flexible plastic type. Thus, even though the chixels 202 themselves may be rigid, a sufficient number of chixel gaps 304 are provided in an appropriate arrangement that a desired bend radius of the flexible substrate 208 is obtained.

Chixels 202 may employ different light emitting technologies, such as LED, electroluminescence, plasma tubes or cells, and backlit LCD. FIGS. 11 and 12 show an exemplary method of manufacturing an LED-based chixel. An LED is formed by depositing an n-doped semiconductor and a p-doped semiconductor layer on a substrate. Light is formed at the p-n junction when it is excited by electrical current. As shown in FIG. 11 an LED wafer 1100 may be produced that includes a plurality of spaced apart LED stacks 1104 that, as discussed in more detail below, may serve as light emitters for a flexible display. As shown in FIG. 12 the LED wafer 1100 may comprise a rigid substrate 1 102 having a plurality of LED stacks 1104 thereon. For example, as shown in FIG. 13 an LED stack 1 104 may include a p-doped layer 1 106 and an n-doped layer 1108 that are provided atop a sapphire substrate 1102 and have the appropriate properties to emit light when supplied with an appropriate charge (current).

Various techniques can be used to create the LED stacks with great accuracy. Portions of the layers 1106, 1 108 may be removed to create separate LED stacks on the rigid substrate separated from one another by a gap 11 10 that generally corresponds to a subpixel or pixel gap of a completed display. For example, a mask may be applied and etching techniques used to etch channels through the upper layers 1106, 1 108 down to the substrate to produce stacks that share a common substrate 1102. In an exemplary embodiment LED stacks may be generally square having a length of about 320 μm and a width of about 320 μm and a gap between the LED stacks 1 104 of about 50 μm. Applicant has found that a layer of n-GaN of about 0.2 μm thickness and a p-GaN layer of about a 0.2 μm thickness on a sapphire substrate of a thickness of about 350 μm can be used to produce LEDs that emit blue light having a wavelength of about 450 nm. Different layers may be used or additional layers added to the LED stacks to obtain LEDs that emit light with desired characteristics. Furthermore, as discussed in more detail below, filters, photoconverters, and other apparatus may be used to manipulate the light emitted from the LEDs. In order to make the LED stacks 1104 into workable LEDs, a p-contact 1120 and an n-contact 1122 may be provided to the stacks 1 104 as shown in FIG. 14 to form an LED 1400. The p-contact 1120 may be provided in a cutout area 1130 of the p-doped layer 1108. For example, an etching process may be used to remove a portion of the p-doped layer to allow the n-contact 1122to be placed directly on top of the n-doped layer 1106. This allows the p-contact to be placed directly atop of the n-doped layer 1106 and conductors 1140 to extend upward from the LED to a rear mounted display driver when the LEDs are incorporated into a display. This obviates the need of providing a large space between the light emitters for providing a pathway for conductors running along the edge and side of the light emitter and thereby allows the LEDs to be tightly packed. The wafer may be processed by etching, ablation, or other known techniques to form LEDs of various shapes, such as the LED 1700 shown in FIG. 17 and arranged in a desired arrangement.

Additional layers can also be added to the LEDs 1400. For example, as shown in an exemplary LED 1600 in FIG. 16 a luminescent phosphor layer 1610, typically a powder phosphor formulated based on the light output of the LED to provide the best conversion, may be provided for color conversion, to convert the emitted blue light to white. The color conversion layer 1610 may be added by known techniques. As shown in FIGS. 14 and 16 when an appropriate current is applied, light is transmitted downwardly from the LED 1400, 1600. Thus, in these embodiments the substrate 1102 is transmissive.

The wafer 1 100 may include different layers on different LED stacks to provide different light characteristics. For example, different layers could be used to produce red, blue, and green light from different LED stacks 1104. The wafer 1100 could also be made of uniform LED stacks 1104 having the same or similar properties. For example, the LED stacks 1104 could be constructed to emit white light or blue light which could then be filtered to produce light with desired characteristics. In the exemplary embodiment shown in FIG. 14 in which GaN layers are used, blue light is emitted. Filters may also be used to provide red, green and blue LEDs which could define red, green and blue subpixels of an RGB pixel display. As seen in FIG. 16 a white phosphor photoconversion layer 1610 can be applied so that the light emitted from the LED 1600 is white which is more efficiently filtered than blue light.

As shown in FIGS. 18A-B an LED wafer 1800 may include an array of uniformly spaced rectangular-shaped LEDs 1802. The LEDs 1802 define subpixels 1803 that may be incorporated into a flexible display. The subpixels 1803 are spaced apart a horizontal distance hi that forms a subpixel gap 1808. A group of LEDs, such as three LEDs, may be used to define an addressable pixel 1804 for a display. A larger array of LEDs may define a chixel 1806 which may include multiple subpixels and pixels. In the exemplary embodiment shown in FIG. 19 the chixel 1806 includes 8 rows of 12 LEDs which define 96 subpixels and 32 three-LED pixels 1804 of the chixel 1806 to provide a 4 X 8 pixel arrangement. Commands/instructions from a driver may be directed to the LEDs of the pixel grouping to manipulate the individual LEDs 1802 as subpixels so that the overall light produced by the pixel 1804 is of desired characteristics, such as a desired color and brightness. Multiple chixels 1806 may be coupled to a flexible substrate 208 to form a flexible display 2000. For example, as shown in FIG. 20 chixels 1806 may be coupled to a flexible substrate 208 in an arrangement 2202. The arrangement of the subpixels 1803 on the individual chixel 1806 in conjunction with the arrangement of the chixels 1806 on the substrate 208 may be such as to provide uniform LED spacing and hence uniform subpixel and pixel spacing across the display 100. In addition, the pixel gap 306 may be uniform across the display and may be set equal to the pixel gap 308. By providing the subpixels 1802 about the edge of the chixel 1806, and removing a predetermined amount of the substrate 208 in the dicing process, the chixel gap 304 may be such that the pixel gap 306 between pixels on adjacent chixels 202 is the same as the pixel gap between pixels on the same chixel and the pixel gap is equal to the subpixel gap. This provides for a uniform display with minimal gap lines. While discussed primarily in terms of the lateral spacing of the subpixels, pixels, and chixels, the same principles apply to the spacing of the subpixels, pixels, and chixels in other directions, such as the vertical gaps. The size of the pixels 1804 can be varied depending upon the desired resolution and use of the display. For example, the size of the subpixels and pixels 1804 within a chixel 1806 incorporated into a display intended for use at a viewing distance of 10 feet may be smaller than a display meant to be used at a viewing distance of 100 feet, even though the displays have the same resolution. As discussed above, the chixels 202 may be coupled to a flexible substrate 208 to form a flexible display 100. In addition to providing support to the chixels 202 the substrate 208 may also provide additional functions, such as filtering, light diffusion, contrast enhancement, etc., and may be comprised of multiple layers. An exemplary flexible substrate 2200 shown in FIG. 22 comprises a diffusion layer 2202, a contrast enhancement layer 2204, and an outer protective layer 2206. The flexible substrate 2200 may also include an adhesive layer 2208 for coupling chixels 202 to the flexible substrate 2200 and one or more filters 2210, as well as an anti -reflective layer 2212 (not shown).

The chixels 1600 may be placed light-emitting end down on the substrate 208 as shown in FIG. 23 so as to emit light through the flexible substrate 2200. The exposed p 1120 and n 1122 contacts allow the display to be driven from the rear by a drive system 2402 as shown in FIG. 23, thereby avoiding the complications of providing transparent front electrodes to the LED subpixels. As discussed above with reference to FIGS 3A-3B the chixels 1600 are arranged on the substrate 2200 so that the resulting chixel gaps 304 provide sufficient bending areas to give the substrate 2200 a desired amount of flexibility. The drive means may address the subpixels in predetermined pixel groupings.

As shown in FIG. 22 the substrate may be provided with one or more filters 2210 to manipulate the light emitted from the LED light emitters. For example, an array of color filters can be printed, sprayed or otherwise provided to the substrate 2200. As seen in FIG. 26 a red-green-blue filter arrangement 2602 having filter portions 2604A, 2604B, 2604C of red R, green G and blue B may be added to the substrate assembly 2200 to form a filtered substrate 2702 with filter portions 2604 that correspond with the different LED light emitters 1600A, 1600B₅ 1600C of a chixel 1600. The chixel 1600 is coupled to the filtered substrate to form a color display 2700 so that the light emitters 1600 align with the filtered portions 2604 to form RGB pixels 2702A, 2702B, 2702C as shown in FIG. 27.

As shown in Fig. 24 drive means 2402 may be provided to the chixels to provide the necessary power and commands to make the light emitters of the chixels emit light in a desired manner. The drive means 2402 may include drive electronics as known in the art. In the exemplary embodiment shown in FIG. 25, a controller 2502 is provided for each chixel. The controller 2502 may comprise a data line and a power line that controls the emission of light from each of the light emitters on a particular chixel 1600. By providing individual chixels with a controller 2502, chixel units can be provided which can be premade and ready to install in a display. Other filter arrangements may be provided in lieu of the standard RGB filter arrangement discussed above, in which each filter covers a single light emitter. For example, in the exemplary embodiment shown in FIGS. 28-30 edge filters 2804 are arranged horizontally to cover portions of more than one light emitter. These edge filters further minimize the effect of the chixel gaps 304. In addition, the chixels may be sized to include edge light emitters in addition to standard three-subpixel multiples.

Chixel gaps may to be more noticeable when the display 100 is flexed into a non-flat condition. As shown in FIG. 28 in addition to the standard lateral RGB filter arrangement of the filter arrangement 2602 in FIG. 26, the filters that correspond to light emitters 1600 at the outer edge of a chixel 2802 referred to as edge emitters 2810 may be sized and shaped to cover edge emitters of two adjacent chixels 2802. For example, edge filters 2804 may be provided to bridge the chixel gap 304 between adjacent chixels 2802 and cover edge light emitters 2810 on each chixel 2802. These edge filters 2804 may be oriented horizontally and may be of a size as to together cover an edge light emitter 2810 on adjacent chixels 2802 in a vertical RGB arrangement. For example, as shown in FIG. 28 a row of 14 light emitters 1600 on a chixel 2802 include 12 center light emitters and two edge emitters 2810. The chixel 2802 may be arranged on a filtered substrate 2906 having vertical filter portions 2604 and edge filters 2804 so that the center 12 light emitters 1600 correspond with a row of 12 vertically oriented red 2604 A, green 2604B or blue 2604C filters and the two edge light emitters 2810 correspond with colored edge filters 2804A-C.

Instead of covering a single light emitter on one chixel, the edge filter are sized and oriented to cover an edge light emitter 2810 on each chixel thereby bridging the chixel gap. In addition, the edge filters may be of a size such that multiple edge filters cover the adjacent light emitters. For example, red, green and blue edge filters may be arranged to cover adjacent edge light emitters in a vertical RGB pattern. The same may be done along the upper and lower edges of adjacent chixels. In addition to having the 12 RGB filters which correspond to 4 RGB pixels, an extra light emitter may be provided at each edge of the chixel to form a row of 14 light emitters. Thus, when two chixels are placed next to one another two edge pixels/light emitters are adjacent one another. It should be noted that while the subpixels and filters are generally discussed as corresponding with a single light emitter, filters may cover multiple light emitters. For example, a subpixel of a chixel could include three vertically aligned light emitters which could be cover by a red filter to define a red subpixel.

FIG. 31 shows another exemplary filter pattern 3102 that may be used in conjunction with a chixel 2802 in which upper and lower end filters 3104 are elongated to filter adjacent upper and lower light emitters 2820 across the chixel gap 304 in FIG. 32. Although each upper edge filter 3104 is shown as a single color filter that covers two adjacent light emitters from adjacent chixels 2802A-B, the filters could be sized so that each light emitter is covered by a red, green, and blue filter.

Because the edge filters span the chixel gap, there is a portion of the filter that is covering a non-emitting area of the display. This could result in a dark spot in the subpixel. Several techniques may be used to eliminate this spot. For example, pixel compensation techniques may be introduced into the driving scheme. In a typical scheme, the luminance of each subpixel is mapped, and the voltage supplied to the subpixel is adjusted so that all subpixels are uniformly bright. Another technique to lessen or eliminate a dark spot in a subpixel corresponding to the area over the chixel gap is the use of diffusion filters or optical lenses. The diffusion filter diffuses, or spreads out or scatters, light from the light emitter. Optical lenses manipulate the emitted light, for example by directing it in a desired direction.

As described herein, pixel chips or chixels may be comprised of light emitters such as organic LEDs or OLEDs, according to an exemplary embodiment of the invention. The use of OLEDs in chixels may increase the operational life of the resulting flexible display, according to an exemplary embodiment of the invention. The OLEDs may emit monocolor light, according to an exemplary embodiment of the invention. For example, white OLEDs may be provided with filters or color conversion to form color-emitting OLEDs. For instance, white OLEDs may be provided with filters or color conversion to form red, green, and/or blue color-emitting OLEDs, according to an exemplary embodiment of the invention. It will be appreciated that in alternative embodiments of the invention, colored OLEDs with or without filters and/or color conversion may likewise be utilized without departing from exemplary embodiments of the invention. Likewise, it will be appreciated that while OLEDs have been described herein for illustrative purposes, the disclosures are likewise applicable to polymer-based LEDs (PLEDs) and yet other LEDs without departing from exemplary embodiments of the invention.

FIG. 33 illustrates an example chixel 3300 that includes a plurality of OLEDs. Each chixel 3300 may be utilized in accordance with one or more chixel arrangements on a flexible display substrate as described herein to form a flexible display. In FIG. 33, the OLEDs may be utilized to form subpixels 3302. For example, OLEDs may form red, green, or blue subpixels 3302. In an exemplary embodiment of the invention, a grouping of red, green, and blue subpixels 3302 may comprise a pixel, although other color combinations may be utilized as well.

According to an exemplary embodiment of the invention, the OLEDs may require both a front electrical connection and a rear electronic connection during operation. As shown in FIG. 33, first via connections 3304 may be provided to form front row electrical connections (e.g., a row conductor) while second via connections 3306 may be provided to form rear column electrical connections (e.g., a column conductor). According to an exemplary embodiment of the invention, the via connections 3304 or 3306 may be formed by drilling, etching, or otherwise forming a throughhole and filling the throughhole with a conductive material or paste. It will be appreciated that the size of the hole and the conductive material or paste provided therein may depend at least in part on the desired current carrying capacity of the OLEDs. Other considerations may be the size of the subpixel, manufacturing techniques, and costs. In an alternative embodiment of the invention, the via connections 3304 or 3306 may also be replaced with a wire connection without departing from exemplary embodiments of the invention,

FIG. 34 illustrates an example stackup for a chixel 3300 of FIG. 33. As shown in FIG. 34, the example stackup for a chixel 3300 may include a first glass substrate layer 3402 (or plastic-based substrate), a routing layer for conductive leads 3404 such as conductive aluminum leads, one or more OLEDs 3406, a visually transparent conductive layer 3408 such as indium tin oxide (ITO), a second glass substrate layer 3410 (or plastic-based substrate), and optionally, one or more color filters or color conversion 3412. The first via connections 3304 may connect the transparent conductive layer 3408 (e.g., ITO) to an electrical source at a rear surface of the chixel 3300. Similarly, the second via connections 3306 may connect the conductive leads 3404 (e.g., Al leads) to another electrical source at the rear surface of the chixel 3300. Accordingly, by providing rear electrical connections through via connections 3304 and 3306, the OLEDs 3406 may be driven using driver means at a non-emissive side of the chixel 3300.

An OLED 3406 may illuminate when current is driven from the front conductive layer 3408 to the rear conductive lead 3404 sandwiching an OLED 3406. Light emitted by the OLED 3406 may be filtered by one or more color filters or color conversion 3412. According to an exemplary embodiment of the invention, the filter or color conversion 3412 may be a separate layer adhered to a surface of the glass substrate layer 3410. Alternatively, the filter or color conversion 3412 may also be formed as part of the glass substrate layer 3410, according to an exemplary embodiment of the invention. As described herein, the OLEDs 3406 may be monocolor (e.g., white, blue, etc.) and filtered with filters 3412 to form color-emitting OLEDs 3406. FIG. 35 illustrates a top planar view of the one or more bottom conductive leads 3404 in FIG. 34. The one or more bottom conductive leads 3404 may be aluminum leads, according to an exemplary embodiment of the invention. In FIG. 35, the conductive leads 3404 may operate as column conductors for the OLEDs 3406. For example, the column conductors may interconnect OLEDs 3406 that are in the same column. FIG. 35 illustrates six (6) column conductors connected to six via connections 3306 for the six columns of OLEDs 3406. FIG. 36 illustrates a top planar view of the one or more top transparent conductive layers 3408 (e.g., ITO) in FIG. 34, according to an exemplary embodiment of the invention. In FIG. 34, the transparent conductive layers 3408 may operate row conductors for the OLEDs 3406. For example, the row conductors may interconnect OLEDs 3406 that are in the same row. FIG. 35 illustrates three rows conductors connected to three via connections 3304 for the three rows of OLEDs 3406. It will be appreciated that in some exemplary embodiments of the invention, the transparent conductive layers 3408 may not be actually transparent. For example, in some applications, a thin wire may be utilized for the conductive layer 3408. However, the thin wire may be visually transparent when viewed at least from a particular distance from the flexible display.

FIG. 37 illustrates an alternative example of a stackup for a chixel, according to an example embodiment of the invention. As shown in FIG. 37, the stackup for a chixel may include ceramic substrate 3702 such as an alumina ceramic substrate, one or more conductive leads 3404 such as conductive aluminum leads, one or more OLEDs 3706, a visually transparent conductive layer 3708 such as indium tin oxide (ITO), a polymer layer 3710, and one or more optional color filters or color conversion 3712.

Still referring to FIG. 37, the stackup may also include one or more first via connections 3714 that connect the transparent conductive layer 3708 (e.g., ITO) to an electrical source at the rear of the chixel. Similarly, the one or more second via connections 3706 may connect the conductive leads 3704 (e.g., Al leads) to another electrical source at the rear surface of the chixel. By providing rear electrical connections through via connections 3704 and 3706, the OLEDs 3706 may be driven using driver means from a non- emissive side of the chixel.

In FIG. 37, the use of alumina ceramic for the ceramic substrate 3702 may provide for an impervious substrate that can easily be processed with conventional technologies to create throughholes for via connections 3714 and 3716. Additionally, the conductive leads 3404 may also be disposed on a surface of alumina ceramic using inkjet, vapor deposition, screen print technologies, or yet other similar technologies. Moreover, the use of alumina ceramic may provide high temperature operation that may be necessary for TFT/active-matrix chixels. This additionally benefits manufacturing because active matrix addressing of the chixel requires fewer contacts on the back of the chixel than does passive matrix addressing. It will be appreciated that while FIG. 37 illustrates the use of an alumina ceramic as the substrate 3702, suitable substrates may include 96% alumina, 99.5% alumina, aluminum nitride, silicon nitride, mullite, and a variety of glass-ceramic materials.

Still referring to FIG. 37, the polymer layer 3710 may be a polymer encapsulate, according to an example embodiment of the invention. For example, the polymer layer 3710 may include one or more polymer encapsulation layers such as Vitex Systems' Barix resin mixture. In an example embodiment of the invention, the polymer layer 3710 may be utilized to seal or otherwise encapsulate the chixel, which may include one or more edges or gaps of the chixel.

FIG. 38 illustrates an exemplary chixel arrangement in accordance with an exemplary embodiment of the invention. In FIG. 38, two chixels 3800a and 3800b are illustrated, although it will be appreciated that a plurality of other chixels may be necessary to form a flexible display. Each chixel 3800a, 3800b may include a plurality of OLEDs 3802. According to an example embodiment of the invention, an OLED 3802 may be provided with a corresponding filter 3804. For example, the filter 3804 may be oriented in generally the same direction as the OLED 3802 and cover a substantial portion of the OLED 3802, as generally shown in FIG. 38 However, according to an exemplary embodiment of the invention, certain filters 3708 may be provided to bridge a gap 3806 between the two chixels 3800a, 3800b. For example, one or more horizontal filters 3808 (e.g., red, green, and/or blue filters) may cover a right-edge OLED 3802 in the first chixel 3800a and an adjacent left-edge OLED 3802 in the second chixel 3800b. With this configuration, two or more adjacent OLEDs 3802 separated by a gap 3806 may be utilized to form one or more subpixels, including red, green, and/or blue subpixels. According to an exemplary embodiment of the invention, one or more optical lenses (e.g., Fresnel or holographic lens) may be provided between the filter 3804 and an edge OLED 3802 to focus light transmitted from OLEDs 3802 to a center portion of the filters 3808.

FIG. 39 illustrates an example row cross-bar connections that may be utilized with OLEDs, according to an exemplary embodiment of the invention. As shown in FIG. 39, a transparent conductor 3904, which may be connected to a via connection 3902, may be utilized as a row conductor for the OLEDs 3902. However, as described herein, some OLEDs 3802 at an edge of the chixels 3800a, 3800b may utilized to form more than one subpixel. Accordingly, it may be necessary to illuminate multiple portions of those OLEDs 3802 at the edge of the chixels 3800a, 3800b. In this situation, a conductive cross bar 3906 may be provided to illuminate multiple portions of an OLED 3802. For example, the cross bar 3906 may be utilized to provide current to the top, middle, and/or bottom portion of a single OLED 3802. In this way, a single OLED 3802 may form at least a portion of several subpixels such as red, green, and blue subpixels.

FIG. 40 illustrates an alternative embodiment in which two OLEDs may be utilized to form a single subpixel. For example, in FIG. 40, there may be two adjacent chixels 4002a, 4002b. A chixel gap 4004 may be defined between the two chixels 4002a, 4002b. A subpixel may associated with a filter 4006 that covers two edge OLEDs — an edge OLED from chixel 4002a and an edge OLED from chixel 4002b, according to an exemplary embodiment of the invention. FIG. 40 also illustrates the electrical connections 4008 for the column conductors. In particular, respective electrical connections 4008 may generally power respective column conductors for each column of OLEDs. However, where OLEDs from two chixels 4002a, 4002b form a single subpixel, a single electrical connection 4010 may be shared for the two column conductors for the two columns of adjacent OLEDs from chixels 4002a and 4002b, according to an exemplary embodiment of the invention. FIG. 41 illustrates another exemplary embodiment of the invention in which two

OLEDs may be utilized to form a single subpixel. As shown in FIG. 41, a flexible display may be comprised of a top chixel 4102a and a bottom chixel 4102b. The top and bottom chixels 4102a, 4102b may be separated by a chixel gap 4104, according to an exemplary embodiment of the invention. As shown in FIG. 41, a color filter 4106 may extend from a bottom OLED of the top chixel 4102a to a top OLED of the bottom chixel 4102b. In this configuration, the color filter 4106 may cover two OLEDs and be associated with a subpixel according to an exemplary embodiment of the invention. For example, the subpixel may be a red subpixel, a green subpixel, blue subpixel, or yet other colored pixels.

FIG. 42 illustrates an alternative arrangement of OLEDs for a chixel, according to an exemplary embodiment of the invention. As shown in FIG. 42, a chixel 4202 may include

OLEDs 4204 that are arranged in an alternating row pattern. For example, every other row of OLEDs 4204 may be aligned in a vertical direction. Accordingly, a single column conductor in the chixel 4202 may electrically contact OLEDs 4204 in alternating rows, according to an exemplary embodiment of the invention, In FIG. 42, the alternating row pattern may minimize the continuity of gaps between OLEDs 4204, according to an exemplary embodiment of the invention. FIG. 43 illustrates a chixel 4302 that may utilize hexagonal-shaped OLEDs 4304, according to an exemplary embodiment of the invention. In FIG. 43, the arrangement of the hexagonal-shaped OLEDs 4304 may minimize the continuity of gaps between the hexagonal- shaped OLEDs 4304. It will be appreciated that other shapes of OLEDs may also be utilized for the chixels, including circular triangular, and other polygonal-shaped OLEDs without departing from example embodiments of the invention. Furthermore, while the chixels may have been illustrated herein as being rectangular, the chixels may likewise be circular, triangular, hexagonal, or polygonal -shaped, according to exemplary embodiments of the invention. FIG. 44 illustrates an alternative chixel stackup with a structure that eliminates the need for via connections for electrical connection, according to an exemplary embodiment of the invention. As shown in FIG. 44a the stackup may include a first glass or plastic-based substrate layer 4402, one or more OLEDs 4406, a visually transparent conductive layer 4408 such as ITO, a second glass or plastic-based substrate later 4410, and, optionally, one or more color filters of color conversion 4412. The second substrate layer 4410 is provided in such a way that electrical contact pads on the first substrate layer 4402 are exposed in order to facilitate electrical connection. As shown in FIG. 44b, the second substrate layer 4410 may be formed with indentations 4414 along the edge. The second substrate layer 4410 is positioned such that the indentations 4414 correspond to electrical contact pads 4416 on the first substrate layer 4402. These indentations 4414 may be of any shape that best complements the contact pad 4410, such as a scallop as shown in FIG. 44b. Alternatively, as shown in FIG. 44c, the second substrate layer 4410 may be manufactured or cut to be smaller than the first substrate layer 4402. When positioned on the stack, the second substrate layer 4410 is placed such that electrical contact pads 4416 on the first substrate layer 4402 are exposed. Electrical connection of the contact pad 4416 to a lead on the second substrate layer 4410 may be made by connecting a conductor 4418, such as a thin wire, to the contact pad 4416 using epoxy or solder. The conductor 4418 may then be routed along the edge and to the top surface of the second substrate layer 4410 to connect with leads.

In another exemplary embodiment of a chixel stackup, a metal contact pad may be formed on a substrate layer as shown in FIG. 45. The metal contact pad 4516 is deposited on the first or second substrate layer 4502 or 4510 by methods known in the art. The metal contact pad 4516 extends from one side of the substrate layer, around the edge, and onto the opposite side of the substrate layer. On either side of the substrate layer 4502 or 4510, the metal contact pad 4516 may connect to leads, such as aluminum leads on the first substrate layer 4502 or ITO leads on the second substrate layer 4510.

Moisture management is a key to OLED lifetime. Traditionally OLEDs are provided with a getter material and the edges of the substrate layers are sealed; no sealing method is 100% effective. In an exemplary embodiment of this invention, the OLED stack is protected against moisture through Defense-in-Depth, where multiple methods of moisture management are implemented concurrently so as to provide the most moisture protection possible. This redundancy protects against failure in one moisture management system and provides multiple mechanisms through which moisture can be removed from the OLED stack in order to attain the highest possible percentage of moisture removal. In additional to the edge sealing and getter methods known in the art, there are other moisture management techniques that may be employed and are described below; it will be appreciated that any of these methods may be used singly or in combination with any number of other techniques.

In one moisture management technique, getter material may be supplied to each OLED chixel. Additionally, getter material may be applied to the entire display area. Getter is available in tape form with or without adhesive; as such, it may be applied to the backplane onto which the OLED chixels are mounted.

Another moisture management technique focuses on the moisture that may enter the OLED stack through the substrates due to defects in the surfaces or crystal structure. In order to minimize the amount of moisture that penetrates the rear (non-emitting side) substrate, which may be glass, plastic or ceramic, the side of the substrate opposite the OLED stack may be coated with metal or a layer of metalized plastic may be applied using a pressure sensitive adhesive or other suitable mounting method. Additionally, the flex circuit, made of Kapton or some other suitable material, onto which the OLEDs are electrically connected may be coated with metal. The metal layer may be in the form of a foil; the metal may be sputtered, evaporated or plated. Preferable metals include aluminum and copper.

As an alternative to the above substrates, Vitex Systems' Barix (or other suitable encapsulation material) may be used as a substrate for the OLED stack. In another moisture management method, the entire assembled display may be coated on the emitting side with Barix or other encapsulation material. These may be deposited by appropriate methods within the temperature range allowed by the OLED stacks (maximum temperature ~125°C) or applied as a tape with pressure sensitive adhesive coated on one side of the Barix. If the Barix is applied as a tape, the PSA may be provided in strips. In this manner, channels will be formed upon application through which dry, inert gas may be flowed. This gas may flow continuously so as to maintain a dry environment or may be flowed only in the presence of a teak that would allow moist air into the display assembly. If used as either substrate or display coating, single or multiple layers of Barix may be applied.

In an additional method of managing moisture, the entire display unit may be slightly over pressurized, by as little as 0.25 psi or less, with a dry, inert gas such as nitrogen. In the event that a seal fails at the exterior edges of the display, the over pressurized gas would be forced out of the display instead of allowing any ambient air, which may be very humid, from entering the display. The pressure may be sustained until the seal can be repaired by attaching a small compressed gas cylinder to a port provided on the display. An indicator may be provided to alert the user of a leak or an empty compressed gas cylinder.

In the OLED structure of this invention, the vias establish a point at which moisture could be introduced to the stack. In order to minimize this direct route of possible moisture entry to the stack, the vias may be formed through multiple layers of flexible material and offset, as shown in FIG. 46 as an alternative structure to the second via connection 3306 (shown in FIG. 36) column conductor. Multiple flexible layers, divided in to lower 4602 and upper 4604 sections are added to the rear of the OLED stack. Between the lower 4602 and upper 4604 sections of flexible layers is a conductive trace 4606, preferably formed of copper. A lower via 4608 is formed in the lower 4602 section of flexible layers for connecting the aluminum leads 3404 at the rear of the OLED stack to the conductive trace 4606. An upper via 4610 is formed in the upper 4604 section of flexible layers for connecting the conductive trace 4606 to driver electronics. The same offset via structure may be used as an alternative to the first via connection 3304 row conductor. A second conductive trace 4616 is provided between the lower 4602 and upper 4604 sections of flexible material, and lower 4612 and upper 4614 vias are formed in the flexible layers, respectively. Lower via 4612 connects the ITO layer 3408 to the second conductive trace 4616, and upper via 4614 connects the second conductive trace 4616 to driver electronics.

In another embodiment of the invention, the OLED may be provided in a contained form rather than as a stack. As an example, an OLED may be provided in a hollow three- dimensional container. It will be appreciated that the container may be any three-dimensional shape of any size, such as by way of example and not limitation, a sphere, cylinder or rectangular prism. The container may be used to provide a 3-D OLED to be used as a subpixel, pixel or group of subpixels or pixels. The container is preferably made of glass. In one exemplary embodiment, the 3-D OLED may be provided in a rectangular prism. The prism is provided as two halves, divided along the length of the prism. The OLED material may be deposited in one half of the container, and then the two halves may be rejoined and sealed. Electrical connections may be made through vias provided in the container. In this form, the 3-D OLED may be used to form an entire row or column of the display.

In another embodiment of the invention, all LEDs on a chixel that are in the same row of the display are connected to a common anode, or row connection. This allows there to be only one connection point to the row conductor for each chixel, thereby reducing the number of connections that must be formed.

As mentioned previously, chixels 202 may employ different light emitting technologies, such as backlit or reflective LCD, OLED, electroluminescence, plasma tubes or cells, quantum dots and LED. FIGs. 47-49 show an exemplary method of manufacturing an LCD-based chixel. As shown in FIG 47, an LCD stack 5100 is formed by depositing liquid crystal molecules 5136 between front glass 5102 and back glass 5108 layers, each with transparent electrodes. A mirror and/or backlight 5130 (fluorescent tube or LED, commonly) is provided for reflective and backlit LCDs, respectively. A diffuser 5132 evenly spreads the light from the mirror and/or backlight to the layers above. Polarizing filter 5134 polarizes the light from the backlight/reflector 5130 as required for the liquid crystal molecules 5136 to transmit the light. Polarizing filter 5140 is provided at a right angle to polarizing filter 5134 and allows the light transmitted from the liquid crystal molecules to pass through. An edge sealant 5138 is used between the two pieces of glass.

An LCD stack according to one exemplary embodiment of the invention is shown in FIG. 48A. ITO contacts on the front glass 5102 are exposed at the edges for electrical connection. ITO columns 5104 are formed on the front glass 5102 of the LCD stack 5100 and extend to one contact edge 5106 of the front glass 5102. ITO row contact pads 5103 are also provided on one edge of the glass adjacent the contact edge 5106 to which the columns extend. ITO rows 5110 are formed on the back glass 5108 of the LCD stack 5100; these rows 5110 extend to one contact edge 5112 of the back glass 5108. The back glass 5108 is smaller than the front glass 5102 so that the ITO columns 5104 and row contact pads 5106 on the front glass 5102 are exposed after the LCD stack 5100 is formed, For example the back glass edge dimension 5120 may be 0.10 mm and the front glass contact edge dimensions 5122 may be 0.60 mm on the two edges with ITO columns or contact pads, and the two non-contact front glass edges 5124 may be 0.10 mm.

In another exemplary embodiment of the invention, as shown in FIG. 48B, wraparound contacts are formed to ease electrical connection to the rows and columns of the LCD chixel. As seen in FIGs. 48C and 48D, ITO columns 5104 are formed on the front glass 5102 of the LCD stack 5100 that extend to one contact edge 5106 of the front glass 5102. A metal column edge contact pad 51 14 is formed on each column 5104, overlapping the ITO by 0.20 mm, and continues around the contact edge 5106 of the front glass 5102. ITO rows 5110 are formed on the back glass 5108 of the LCD stack 5100. These rows 51 10 extend to one contact edge 51 12 of the back glass 5108. A metal row edge contact pad 51 16 is formed on each row 51 10, overlapping the ITO row by 0.20 mm, and continues around the contact edge 5112 of the back glass 5108. A flex bond connects the wraparound edge contacts to the drive electronics. Column flex bond 5130 connects the metal column edge contact pad 5114 from the front glass 5104 of the LCD stack 5100 to the drive electronics (not shown). Row flex bond 5132 connects the metal row edge contact pad 1116 from the back glass 5108 of the LCD stack 5100 to the drive electronics (not shown).

As shown in FIG. 49, the number of pixels or subpixels on a chixel is determined by the arrangement of the color filter for a color LCD. The color filter 5204 defines subpixels

5203 of desired colors that may be incorporated into a flexible display. The subpixels 5203 are spaced apart a horizontal distance hi that forms a subpixel gap 5206. Each repeating unit of the color pattern subpixels defines a pixel 5205.

As shown in FIG. 50, multiple chixels 5302 may be coupled to a flexible substrate 208 to form a flexible display 5300. For example, as shown in FIG. 50 chixels 5302 may be coupled to a flexible substrate 208 in an arrangement. The arrangement of the subpixels on the individual chixel 5302 in conjunction with the arrangement of the chixels 5302 on the substrate 208 may be such as to provide uniform LCD spacing and hence uniform subpixel and pixel spacing across the display 5300. In addition, the chixel gap 304 may be uniform across the display and may be set equal to the pixel gap 306. This provides for a uniform display with minimal gap lines. While discussed primarily in terms of the lateral spacing of the subpixels, pixels, and chixels, the same principles apply to the spacing of the subpixels, pixels, and chixels in other directions, such as the vertical gaps. The size of the pixels can be varied depending upon the desired resolution and use of the display. For example, the size of the subpixels and pixels within a chixel 5302 incorporated into a display intended for use at a viewing distance of 10 feet may be smaller than a display meant to be used at a viewing distance of 100 feet, even though the displays have the same resolution.

As discussed above, the chixels 202 may be coupled to a flexible substrate 208 to form a flexible display 100. In addition to providing support to the chixels 202 the substrate 208 may also provide additional functions, such as filtering, light diffusion, contrast enhancement, etc., and may be comprised of multiple layers. An exemplary flexible substrate 5400 shown in FIG. 51 comprises a diffusion layer 5402, a contrast enhancement layer 5404, and an outer protective layer 1406. The flexible substrate 1400 may also include an adhesive layer 5408 for coupling chixels 202 to the flexible substrate 5400 and one or more filters 5410, as well as an anti -reflective layer 5412 (not shown). These light manipulating layers may cover individual emitters or groups of light emitters, depending on the desired result. The chixels 5302 may be placed light-emitting side down on the substrate 208 as shown in FIG. 51 so as to emit light through the flexible substrate 5400. The row and column flex bonds 51 16 and 5114, as shown in FIG. 48D or the row contact pads 5103 and ITO columns 5104 on the contact edge 5106 on the front glass 5102, as shown in FIGs. 48A and 48B, allow the display electrical connections to be made on the back (non-emitting) side of the device. The display is driven by a drive system 5502 that provides data and power to the LCD stack 5100 as shown in FIG. 52, thereby avoiding the complications of providing electrical connection to the front of the LCD. As discussed above with reference to FIGS 3A-3B the chixels 5302 are arranged on the substrate 5400 so that the resulting chixel gaps 304 provide sufficient bending areas to give the substrate 5400 a desired amount of flexibility. The drive means may address the subpixels in predetermined pixel groupings.

As shown in Fig. 53 drive means may be provided to the chixels to provide the necessary power and commands to make the light emitters of the chixels emit light in a desired manner. The drive means may include drive electronics as known in the art. In the exemplary embodiment shown in FIG. 53, a controller 1602 is provided for each chixel. The controller 5602 may comprise a data line and a power line that controls the emission of light from each of the light emitters on a particular chixel 5600. By providing individual chixels with a controller 5602, chixel units can be provided which can be premade and ready to install in a display. Other filter arrangements may be provided in lieu of the standard RGB filter arrangement discussed above, in which each filter covers a single light emitter. For example, in the exemplary embodiment shown in FIG. 54 edge filters 5704 are arranged horizontally to cover portions of more than one light emitter. These edge filters, which may be standard filters or color conversion, further, minimize the effect of the chixel gaps 304 that may to be more noticeable when the display is flexed into a non-flat condition. In addition, the chixels may be sized to include edge light emitters in addition to standard three-subpixel multiples.

Because the edge filters span the chixel gap, there is a portion of the filter that is covering a non-emitting area of the display. This could result in a dark spot in the subpixel. Several techniques may be used to eliminate this spot. For example, pixel compensation techniques may be introduced into the driving scheme. In a typical scheme, the luminance of each subpixel is mapped, and the voltage supplied to the subpixel is adjusted so that all subpixels are uniformly bright. Another technique to lessen or eliminate a dark spot in a subpixel corresponding to the area over the chixel gap is the use of diffusion filters or optical lenses. The diffusion filter diffuses, or spreads out or scatters, light from the light emitter. Optical lenses manipulate the emitted light, for example by directing it in a desired direction. It will be appreciated that other shapes of LCDs may also be utilized for the chixels, including circular triangular, and other polygonal-shaped LCDs without departing from example embodiments of the invention. Furthermore, while the chixels may have been illustrated herein as being rectangular, the chixels may likewise be circular, triangular, hexagonal, or polygonal-shaped, according to exemplary embodiments of the invention.

Many modifications and other embodiments of the inventions set forth herein will come to mind to one skilled in the art to which these inventions pertain having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the inventions are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims

CLAIMSWhat is claimed is

1. A flexible display comprising: a plurality of pixel-containing chips attached to a flexible substrate with a bend gap provided between adjacent chips so as to allow the flexible display to bend in a first direction along a bend radius.

2. The flexible display of claim 1, wherein each of the plurality of pixel-containing chips comprises an array of pixels.

3. The flexible display of claim 2, wherein each pixel in the array of pixels comprises a plurality of sub-pixels.

4. The flexible display of claim 3, wherein each of the plurality of sub-pixels comprises a light-emitting diode.

5. The flexible display of claim 1, wherein each of the plurality of pixel-containing chips comprises a plurality of light emitters affixed to a rigid substrate.

6. The flexible display of claim 2, wherein a first pixel gap is provided between adjacent pixels on each of the plurality of pixel-containing chips and a second pixel gap is provided between adjacent pixels on adjacent pixel -contain ing chips; and wherein each of the plurality of pixel-containing chips are positioned and arranged such that the first pixel gap and the second pixel gap are substantially the same and uniform across the flexible display.

7. The flexible display of claim 1, wherein the flexible substrate comprises a filter film.

8. The flexible display of claim 1, wherein each of the plurality of pixel-containing chips comprises rear contacts adapted to receive current from a conductor, the rear contacts provided on a side of the chip opposite the flexible substrate.

9. The flexible display of claim 1, further comprising a display driver electronically connected to the plurality of pixel-containing chips and adapted to generate a display on the flexible display.

10. The flexible display of claim 1, wherein the flexible substrate comprises a contrast enhancement layer.

11. The flexible display of claim 1, wherein the flexible substrate comprises a diffusion layer.

12. The flexible display of claim 1, wherein each pixel-containing chip is adapted to transmit light through the flexible substrate,

13. The flexible display of claim 1, wherein the flexible display is sufficiently flexible to roll into a cylindrical shape.

14. The flexible display of claim 1, wherein the flexible display is adapted to bend in a horizontal direction and a vertical direction.

15. The flexible display of claim 1, wherein the flexible display has a pixel gap to pixel size ratio equal to or less than 0.25.

16. The flexible display of claim 2, wherein at least one pixel in the array of pixels comprises: a rigid substrate; a first layer of n-doped gallium nitride on a rigid substrate, the first layer of n-doped gallium nitride comprising a first surface portion and a second surface portion; a first layer of p-doped gallium nitride on said first surface portion; a first electrical contact contacting the first layer of p-doped gallium nitride; and a second electrical contact contacting the second surface portion of the first layer of n- doped gallium nitride.

17. The flexible display of claim 16, further comprising a second layer of n-doped gallium nitride on the rigid substrate, the second layer of n- doped gallium nitride comprising a third surface portion and a fourth surface portion; a second layer of p-doped gallium nitride on the third surface portion; a third electrical contact contacting the second layer of p-doped gallium nitride; and a fourth electrical contact contacting the fourth surface portion of the second layer of n-doped gallium nitride.

18, The flexible display of claim 16, further comprising an electronic drive unit electrically connected to the first and second electrical contacts.

19. The flexible display of claim 17, further comprising an electronic drive unit electrically connected to the first, second, third, and fourth electrical contacts.

20 A flexible display, comprising: a plurality of chips that each include a plurality of light emitters; and a flexible substrate for receiving the plurality of chips, wherein the plurality of chips are arranged on the flexible substrate to provide a bending radius for the flexible substrate.

21. The flexible display of claim 20, wherein the light emitters includes (i) light emitting diodes (LEDs), (ii) electroluminescent elements, (iii) plasma tubes or cells, or (iv) LCD.

22. The flexible display of claim 20, wherein the plurality of light emitters form subpixels.

23. The flexible display of claim 22, wherein the subpixels are arranged to form pixels.

24. The flexible display of claim 23, wherein adjacent pixels in a chip include a pixel gap, wherein a ratio of a first size of the pixel gap to a second size of the pixel is about 1 :4,

25. The flexible display of claim 24, wherein the second size of the pixel is a width or height of the pixel.

26. The flexible display of claim 20, wherein the plurality of chips are coupled to the flexible substrate using adhesive.

27. The flexible display of claim 20, wherein the flexible substrate comprises one or more of a contrast layer, a diffusion layer, a filter layer, or an anti-reflection layer.

28. The flexible display of claim 20, wherein at least one of the light emitters is associated with at least one color filter for controlling light emissions.

29. The flexible display of claim 28, wherein the at least one color filter includes red, green, or blue color filters.

30. The flexible display of claim 20, wherein the light emitters are monocolor, and wherein the at least one color filter is utilized for color conversion of the monocolor light emitters.

31. The flexible display of claim 20, wherein the light emitters include white light emitters, blue light emitters, or ultraviolet (UV) light emitters.

32. The flexible display of claim 20, wherein a first chip and a second chip of the plurality of chips are adjacent to each other and define a gap between the first chip and the second chip, and further comprising at least one edge filter for covering at least a portion of the gap.

33. The flexible display of Claim 32, wherein light emitters adjacent to the gap include edge light emitters, wherein the at least one edge filter further extends from at least a portion of a first edge light emitter of the first chip to at least a portion of a second edge light emitter of the second chip.

34. The flexible display of claim 32, wherein the at least one edge filter includes a red edge filter, a green edge filter, and a blue edge filter, wherein the red, green, and blue edge filters extend from the first edge light emitter to the second edge light emitter.

35. The flexible display of claim 20, wherein the plurality of pixels are driven through one or more rear connections opposite an emissive side of the plurality of pixels.

36. The flexible display of claim 20, further comprising a controller for each of the plurality of chips, wherein the controller controls emission of light from the chip.

37. The flexible display of claim 20, wherein the controller includes a data line and power line for controlling emission of light from the chip.

38. A flexible display, comprising: a plurality of chips each comprising one or more LCD stacks; and a flexible display substrate for receiving the plurality of chips, wherein the plurality of chips arranged on the flexible display substrate to provide a bending radius for the flexible substrate.

39. The flexible display of Claim 38, wherein each LCD stack comprises: a first glass layer, a liquid crystal molecule layer, a second glass layer, and a two polarizing layers.

40. The flexible display of Claim 39, wherein the first glass layer includes transparent conductive row electrodes and the second glass layer includes transparent conductive column electrodes.

41. The flexible display of Claim 40, the transparent conductive row electrodes extend to a contact edge of the first glass layer, and the transparent conductive column electrodes extend to a first contact edge of the second glass layer.

42. The flexible display of Claim 41, wherein the first glass layer is smaller than the second glass layer in both length and height dimensions,

43. The flexible display of Claim 42, wherein the second glass layer also includes transparent conductive row contact pads on a second contact edge on the second glass layer adjacent the first contact edge of the second glass layer.

44. The flexible display of Claim 40, wherein metal row edge contacts overlay the transparent conductive row electrodes on the contact edge of the first glass layer and metal column edge contacts overlay the transparent conductive column electrodes on the first contact edge of the second glass layer.

45. The flexible display of Claim 44, wherein metal row edge contacts further extend around the contact edge of the first glass layer and metal column edge contacts further extend around the first contact edge of the second glass layer.

46. The flexible display of Claim 45, wherein a flexible row bond connects the metal row edge contacts to a drive controller and a flexible column bond connects the metal column edge contacts to a drive controller.

47. The flexible display of Claim 46, wherein the flexible row bond and the flexible column bond are electrically conductive.

48. The flexible display of Claim 39, further comprising a display driver that is connected to the LCD stack.

49. The flexible display of Claim 39, wherein at least one LCD stack further includes: a color filter, wherein the color filter is provided on a surface of the second glass layer.

50. The flexible display of Claim 39, further comprising a flexible display substrate, wherein the flexible display substrate comprises one or more of a diffusion layer, a contrast enhancement layer, or an outer protective layer.

51. A flexible display, comprising: a plurality of chips each having a plurality of liquid crystal displays (LCDs); and a flexible substrate for receiving the plurality of the chips, wherein the plurality of chips arranged on the flexible display substrate to provide a bending radius for the flexible substrate.

52. The flexible display of Claim 51, wherein the plurality of chips comprises a first chip and a second chip that are adjacent to each other and form a gap between the first chip and the second chip, and further comprising: at least one filter for covering at least a portion of the gap.

53. The flexible display of Claim 21, wherein the plurality of light emitters comprise organic light emitting diodes (OLEDs) or polymeric light emitting diodes (PLEDs).

54. A flexible display, comprising: a plurality of chips each comprising a plurality of LED stacks; and a flexible display substrate for receiving the plurality of chips, wherein the plurality of chips arranged on the flexible display substrate to provide a bending radius for the flexible substrate.

55. The flexible display of claim 54, wherein each LED stack comprises: a p-doped layer, an n-doped layer, and a substrate layer, wherein the substrate layer and the p-doped layer sandwich the n- doped layer.

56. The flexible display of Claim 55, wherein light is emitted from a side of the substrate layer opposite the p-doped and n-doped layers.

57. The flexible display of Claim 55, wherein the substrate layer is a sapphire substrate layer,

58. The flexible display of Claim 55, wherein the p-doped layer is a p-GaN layer and the n-doped layer is an n-GaN layer.

59. The flexible display of Claim 55, further comprising: an n-contact disposed on a first surface of the n-doped layer, wherein at least a portion of the n-doped layer is disposed between the n-contact and the substrate layer; and a p-contact disposed on a second surface of the p-doped layer, wherein at least a portion of the p-doped layer is disposed between the p-contact and the n-doped layer.

60. The flexible display of Claim 59, further comprising a display driver that is connected to the LED stack via the n-contact and the p-contact.

61. The flexible display of Claim 59, wherein the n-contact is the cathode and the p- contact is the anode.

62. The flexible display of Claim 59, wherein at least one LED stack further includes: a phosphor layer, wherein the phosphor layer is provided on a surface of the substrate layer, wherein the phosphor layer and the n-doped layer sandwich the substrate layer.

63. The flexible display of Claim 62, wherein the phosphor layer is a white luminescent phosphor layer.

64. The flexible display of Claim 62, wherein the phosphor layer is operative to provide color conversion for light emitted from the substrate layer.

65. The flexible display of Claim 62, wherein the color conversion is operative to convert light emitted from the substrate layer to red, green, or blue light.

66. The flexible display of Claim 55, wherein at least one LED stack further includes: a color filter, wherein the color filter is provided on a surface of the substrate layer, wherein the color filter and the n-doped layer sandwich the substrate layer.

67. The flexible display of Claim 55, wherein the flexible display substrate comprises one or more of a diffusion layer, a contrast enhancement layer, or an outer protective layer.

68. The flexible display of Claim 54, wherein at least a portion of the chips further comprise: a transparent conductive layer; and a conductive leads layer, wherein the transparent conductive layer and the conductive leads layer sandwich at least a first portion of the plurality of LEDs.

69. The flexible display of Claim 68, further comprising: a polymer encapsulation layer, wherein the transparent conductive layer is disposed between the polymer encapsulation layer and the first portion of the plurality of LEDs; and a ceramic substrate layer, wherein the conductive leads layer is disposed between the ceramic substrate layer and the first portion of the plurality of LEDs.

70, The flexible display of Claim 69, wherein the ceramic substrate layer is comprised of alumina ceramic.

71. The flexible display of Claim 69, wherein the polymer encapsulation layer is further disposed on one or more side surfaces of the chip, wherein the side surfaces are substantially perpendicular to a top or bottom surface of the chip.

72. The flexible display of Claim 68, further comprising: a first glass or plastic layer, wherein the transparent conductive layer is disposed between the first glass or plastic layer and the first portion of the plurality of LEDs; and a second glass or plastic layer, wherein the conductive leads layer is disposed between the second glass or plastic layer and the first portion of the plurality of LEDs.

73. The flexible display of Claim 72, further comprising: at least one first conductive via that originates at the transparent conductive layer and terminates at the second glass or plastic layer; and at least one second conductive via that originates at the conductive leads layer and terminates at the second glass or plastic layer.

74. The flexible display of Claim 73, wherein the at least one first and second conductive vias are operative to drive at least the first portion of the plurality of LEDs from a non- emissive side of the first portion of the plurality of LEDs.

75. The flexible display of Claim 68, wherein the transparent conductive layer comprises one or more row conductors, and wherein the conductive leads layer comprises one or more column conductors.

76. The flexible display of Claim 68, wherein the transparent conductive layer comprises indium tin oxide (ITO).

77. The flexible display of Claim 68, wherein the conductive leads layer comprises aluminum leads.