CN100439943C - Light-guiding plate and back-light moudle with same - Google Patents

Abstract

The present invention relates to a light guide board and backlight module having said light guide board. The upper surface of said light guide board is outline gradual change v-groove constructional free curved face, lower surface is microlens array architecture, said v-groove one surface toward LED light source being one outline gradual change curved face and another surface is vertical or approximate vertical plane, horizontal included angle of v-groove top curved face contour line tangent being greater than v-groove bottom curved face contour line tangent horizontal included angle. Compared with traditional single side mesh point constructional light guide board, said invention adopts outline gradual change free curved face v-groove structure and mesh point constructional light guide board, having more reasonable light distribution, and in backlight module at least capable of reducing one layer of brightening film, reducing backlight module cost and realizing ideal displaying on low power consuming.

Description

Light guide plate and backlight module with this light guide plate

Technical field

The backlight module that the present invention relates to a kind of light guide plate and have this light guide plate is as the lighting source of dull and stereotyped liquid crystal display (LCD).Can be applicable to mobile phone, handheld devices, LCD computer display, LCD TV, reach in the back lighting of pick-up unit.

Background technology

As everyone knows, because the luminous display device of the right and wrong of LCD own, so must just can reach display effect by backlight.Backlight module provides the optical module of backlight in the LCD display product, and it accounts for 11%～12% of LCD module assembly basis, and therefore, on manufacturing cost, backlight module is very important parts in the LCD module merely.

At present the transmitance of monochromatic liquid crystal display (TN type LCD) is approximately 10～30%, and the transmitance of colour liquid crystal display device is 5～8%, make their display brightness meet or exceed the brightness (130cd/m of CRT (cathode-ray tube (CRT)) ²), the brightness of the former light source should be at 1500cd/m ²More than, and the latter should be at 3500cd/m ²More than.The brightness value uniformity coefficient of display surface is restricted to 0.8 (being 0.87 when the visual angle is 80 °) usually when being 10 ° at the visual angle, qualitative picture is wished and can be reached more than 0.9.

As shown in Figure 1, it is the basic structure of mobile phone backlight module.Because thickness is limit, the lighting system of mobile phone backlight is side light, brightness enhancement film BEF (Brightness Enhancement Film) or compositions such as dual brightness enhancement film (DualBEF) and encapsulating housing that it is mainly placed by LED (or CCFL, i.e. cold-cathode fluorescence lamp) light source, reflector plate, light guide plate (Lightguide), diffusion sheet (Diffuser), two-layer vertical interlaced.

Before the white light LEDs industrialization, the mobile phone backlight generally uses CCFL as light source, and the general life-span of CCFL can reach 20,000 hours, can the reaching more than 50,000 hours of specific (special) requirements, and caliber is 1.2～3.0mm.

Light guide plate is generally made with the method for injection mo(u)lding, and material is the more of PMMA and PC, and popular on the market being generally at present has the light guide plate of single face micro structure array.

Fig. 2 A and 2B are respectively the schematic cross-section (for clarity sake, having omitted profile line) of two kinds of typical backlight modules, and the bottom of light guide plate is the microlens array structure among Fig. 2 A, and the bottom of light guide plate is a V-groove structure among Fig. 2 B.

It is netted that light guide plate bottom among Fig. 2 A has a lot of micro lens to be arranged in, and also is lattice point structure.Lenticular shape can be a spheroidal, taper shape, elliposoidal or tetrahedral angle cone prism shape.Smaller from the local slight lens sizes that led light source is near, bigger away from the local lenslet dimension of led light source.Lenticular main effect is to change radiation direction, and the LED from the light guide plate edge injects when light, forms the light of upwards dispersing after the lenticule refraction through the light guide plate bottom.The light that spills from the lenticule bottom sheet reflected back light guide plate that is reflected is recycling once more.By lenticular size of suitable arrangement and spacing, can obtain whole equally distributed area source.Hereinafter, term " microlens array " is called as " lattice point structure " sometimes, perhaps " micro structure array ".

The known light guide plate that also has another kind of lattice point structure, these sites are to be printed on the bottom surface of light guide plate by the mode of printing, and have the Liquid Paraffin ink dot of very high diffuse reflectance.Generally speaking, lower and the site is less near the dot density of light source, and higher and the site is bigger away from the dot density of light source.Present light guide plate has seldom adopted this form.

Light guide plate among Fig. 2 B bottom all is the same V-groove structure for shape, and the distance between the near local V-groove of LED is than broad, and is narrow away from the distance between the local V-groove of LED.The effect of V-groove follows that in light guide plate bottom microlens array to be set similar, mainly is that the LED pointolite for the steering handle glancing incidence that changes light becomes the upwards equally distributed area source of emission.

In backlight module, the main effect of reflector plate is the light reflected back light guide plate that all are spilt from the light guide plate bottom.Reflector plate is the silver-plated or plating BaSO with white generally ₄The film reflector plate, thickness is 65～230nm usually, reflectivity is greater than 95%.Also can adopt the sheet of aluminizer.

Diffusion sheet is positioned at the top of light guide plate, and its major function is the light that sees through light guide plate to be done scattering handle, to reach atomizing effect.

Brightness enhancement film (also being prism film) is the overall brightness that is used to promote backlight module, and its light that utilizes the full emission of right-angle prism allow and disperse concentrates on bright dipping in the normal 70 degree scopes, allows the light that penetrate greater than 70 degree reflect once more again and is utilized, as shown in Figure 3.The biplate brightness enhancement film vertically overlaps, and to use the brightness can make at the axle center to increase about 110%, makes the light of dispersion concentrate on certain angle and send from backlight module.3M company has also developed a kind of polarization spectro brightness enhancement film, i.e. DBEF at present.As everyone knows, the LCD panel is only by polarized light, and when the polaroid of light by LCD lower floor, 50% the light of having an appointment is absorbed and is wasted.The principle of polarization spectro brightness enhancement film is that absorbed about 50% the polarized light of script is looped back the leaded light brightness enhancement film, again the polarization direction half-twist is become the available polarized light of LCD panel, and circulation can increase brightness about 60% so repeatedly.

Owing to lighten, attenuation, brighten, low power consumption and to reduce production costs be the target that each backlight manufacturer is pursued, and when using brightness enhancement film, as long as optical elements such as backlight module are kept original state, increase the remarkable lifting which floor very thin BEF just can realize LCD brightness.Therefore, each big LCD manufacturing firm all selects to improve brightness with this method.But, because the property right of critical elements one brightness enhancement film in the backlight module also is controlled in the hand of 3M company firmly, and the quantity of 3M brightness enhancement film supply falls short of demand, so the time of stocking up of brightness enhancement film is long, price also high (the brightness enhancement film cost account for the whole backlight module cost about 1/4 or higher).

And because the main effect of light guide plate is the LED pointolite that place the side to be become whole of light guide plate go up equally distributed area source, so the quality of light guide plate design is directly connected to efficient, uniformity coefficient and the brightness of whole backlight module.Therefore, each company reduces by the light guide plate of studying high-level efficiency, high brightness, high uniformity one after another or without the brightness enhancement film in the backlight module, with the supply of material bottleneck problem of solution 3M brightness enhancement film, and reduces production costs now.

Integrated design becomes first-selected method for designing, as the exiting surface of light guide plate directly is injection molded into prism-like, and like this can be only with a brightness enhancement film.Y.Oki has delivered a kind of Sheetless light guide plate, and light conducting plate structure is direct injection mo(u)lding surface on light guide plate, carves the groove of nanometer size, to replace prismatic lens (prism sheet) or brightness enhancement film.Since also can send the above brightness of same brightness with a brightness enhancement film less, thus the cost of the backlight module about 12% not only can be reduced, but also can shorten manufacture process.

At present, also development has a kind of Polarizer backlight module that is made of the polarization light guide plate.Generally speaking, the nonpolarized light that is sent by backlight is only had an appointment 40% can be by the Polarizer under the LCD screen, about 60% light is reflected or is depleted, utilize the brightness that sees through the LCD panel to increase once more if add its polarization direction to be revolved to turn 90 degrees again after Polarizer is reflected this part light, then constitute the Polarizer backlight module.This backlight module can double efficient many.But because the manufacturing cost height of polarization light guide plate puts goods on the market so yet there are no now.

For this reason, the use that how to reduce brightness enhancement film to be effectively reducing cost, and increases the brightness of LCD display, is that this area practitioner remains the further problem of research.

Summary of the invention

The purpose of this invention is to provide a kind of light conducting plate structure with unique design, it not only has effective light transmission efficiency, and can reduce and use BEF even not use BEF, effectively reduces the cost of backlight module thus.

The characteristics of light guide plate of the present invention are that the upper surface of light guide plate is a plurality of V-shaped groove structures, and described V-shaped groove structure has the free form surface of profile gradual change, and lower surface is the microlens array structure.Light guide plate V-shaped groove structure adopts the boundary rays principle design.

Wherein, the boundary rays principle mainly is meant: a continuous aggregate, its mapping also are continuous aggregates, and mapping is one to one, and its border also is the border of another set after through mapping.Be to shine another surface after cluster light changes direction through a continuous surface, it is formed also to be a continuous zone, and adjacent luminous point is still adjacent on the target area, and borderline luminous point is corresponding to the border on the target area.

According to the border principle, V-shaped groove is designed to the curved surface of a profile gradual change towards the one side of led light source, and another side is plane vertical or that have the pitch angle a little (marquis to be designed to have slightly the pitch angle be for easy to process, the easy demoulding when also having injection moulding) sometimes.At the top of V-shaped groove curved surface, the horizontal sextant angle of its outline line tangent line is bigger, and in the bottom of V-shaped groove curved surface, the horizontal sextant angle of outline line tangent line is smaller.The light of low angle incident in the catheter plate is when inciding the top of V-shaped groove, with downward total reflection, and when inciding the bottom of V-shaped groove wheel, to incide the light at V-shaped groove middle part to the last direction total reflection of light guide plate, will be reflected between the position between the two.So each V-shaped groove all is responsible for a very large-area illumination.Along with the variation of V-shaped groove from light source position, the shape of V-shaped groove has different slightly.Utilize the stack of a plurality of V-shaped groove total reflection lights, can produce equally distributed area source.

According to the present invention, backlight module adopts the mode of edge light, and wherein led light source is positioned over a side of this light guide plate, and light advances this light guide plate from the side coupling of this light guide plate.

The tangent slope at V-shaped groove curved surface profile line top is k ₁, the tangent slope of V-shaped groove curved surface profile line bottom is k ₂, the width of V-shaped groove is P, then in this outline line the every bit coordinate (X, the tangent slope k that Y) locates passes through formula $k=\tan ({\tan }^{-1}{k}_1+\frac{X}{P}({\tan }^{-1}{k}_2-{\tan }^{-1}{k}_1))$ Obtain.

The lower surface of this light guide plate can also be other lattice point structure except the lattice point structure that microlens array is set, for example can be taper shape, lattice point structures such as Square-edge taper, the perhaps perpendicular equally distributed V-shaped groove structure of orientation and the orientation of upper surface gradual change V-shaped groove.

Distribute for reaching uniform illumination, the spacing of V-shaped groove is adjusted along with need do some from the distance of LED distance, and from the nearer place of led light source, it is big that the spacing of V-shaped groove is wanted, and promptly V-shaped groove is arranged rarelyr.And less away from led light source V-shaped groove gap ratio, V-shaped groove row must be closeer.The closeest place, the spacing of V-shaped groove is about the twice of V-shaped groove width.For the medium-sized little light guide plate of one-inch, maximum spacing is more than 6 times or 7 times of minimum spacing.

According to design of the present invention, between the 50 μ m, the degree of depth is between 6 μ m to 35 μ m at 15 μ m for the width of described V-shaped groove.The V-shaped groove width of the light guide plate that computer simulation is here adopted is 30 μ m.

The present invention also provides a kind of backlight module with above-mentioned light guide plate, it includes reflector plate, led light source and diffusion sheet from bottom to up successively, wherein be provided with aforesaid light guide plate between reflector plate and diffusion sheet, light guide plate has a side of V-shaped groove structure towards diffusion sheet.In above-mentioned backlight module, above this diffusion sheet, be provided with one deck brightness enhancement film at least.

Show according to test figure, light guide plate of the present invention and the light guide module with this light guide plate not only can effectively increase the brightness of LCD display, and can produce more equally distributed area source, use light guide plate of the present invention and light guide module can reduce the quantity of using brightness enhancement film, thereby reduce manufacturing cost.

Description of drawings

Fig. 1 is the structural representation of traditional mobile phone backlight module;

Fig. 2 A and Fig. 2 B are respectively the schematic cross-section of two kinds of typical backlight modules;

Fig. 3 is the synoptic diagram of brightness enhancement film principle of work;

Fig. 4 is the principle of work synoptic diagram according to the light guide plate of the V-shaped groove structure with profile gradual change of the present invention;

Fig. 5 A is the 3D model of the light guide plate of no any microstructure;

Fig. 5 B is the intensity map of light guide plate among Fig. 5 A;

Fig. 6 A is for having only lower surface to have the 3D model of microlens array structure when light guide plate;

Fig. 6 B is the intensity map of light guide plate among Fig. 6 A;

Fig. 7 A is for having the 3D model that microlens array structure and upper surface have the V-shaped groove structure of profile gradual change when the light guide plate lower surface;

Fig. 7 B is the intensity map of light guide plate among Fig. 7 A;

Fig. 8 is the stereographic map according to the light guide plate of the V-shaped groove structure with microlens array structure and profile gradual change of the present invention; And

Fig. 9 is the synoptic diagram of the computing method of V-shaped groove free form surface.

Embodiment

Below by the light guide plate of specific embodiments of the invention and other type is compared, further specify the present invention.Hereinafter, term " the V-shaped groove structure of profile gradual change " is called " V-shaped groove " or " V-shaped groove structure " sometimes for short.

Fig. 4 is the synoptic diagram of V-shaped groove structure that utilizes the profile gradual change of boundary rays principle design.Wherein, this V-shaped groove structure is made up of a free form surface and the perpendicular that is basically perpendicular to this light guide plate basal plane towards the profile gradual change of led light source.In addition, this light guide plate adopts the edge light mode, and light source is LED or CCFL, is positioned over the side of light guide plate.When the light L1 of low angle incident in the light guide plate incides the A place, top of V-shaped groove outline line,, obtain reflection ray L1 ' thus with downward total reflection; When the light L2 of low angle incident incides the B place, bottom of V-shaped groove outline line, will obtain reflection ray L2 ' thus to the last direction of light guide plate (promptly away from the direction of light source) total reflection; The light that incides the outline line middle part will be reflected between the position between the two, i.e. dash area among Fig. 4.So each V-shaped groove all is responsible for a very large-area illumination, along with the variation of V-shaped groove from light source position, the shape of V-shaped groove also can have different slightly.Utilize the stack of a plurality of V-shaped groove total reflection lights, can produce equally distributed area source.

The outline data of V-shaped groove can be calculated with iterative Integral Method, and it can be input to CAD software and set up solid model and carry out ray tracing.

If the tangent slope at V-shaped groove outline line top is k ₁, the tangent slope of V-shaped groove outline line bottom is k ₂, the V-shaped groove width is P, is that (X, the tangent slope k that Y) locates passes through formula for other all coordinate points of initial point with the top end of V-shaped groove outline line in this V-shaped groove outline line then $k=\tan ({\tan }^{-1}{k}_1+\frac{X}{P}({\tan }^{-1}{k}_2-{\tan }^{-1}{k}_1))$ Obtain.

Below just describe in detail according to the computing method with gradual V-shaped groove of the present invention.

As shown in Figure 9, the thickness of establishing light guide plate is h, and length overall is L, i.e. OR+RQ=L.From the light of the led light source incident at light guide plate edge through the light guide plate total reflection in bottom after, incide on the V-shaped groove of R point position, incide the downward total reflection of light of V-shaped groove forward part, normal is N ₁, the light that incides the V-shaped groove aft section is to the total reflection of the rear portion of light guide plate, and normal is N ₂Because the length of V-shaped groove is compared the length and the thickness of light guide plate with the degree of depth be very small, so the length and the degree of depth for V-shaped groove in the partial arithmetic below can be ignored.

At present the light incidence point M shown in Fig. 9 to the lateral separation of reflection spot R (being the initial position of V-shaped groove) be " ²/ ₃OR ", then can obtain according to the geometric relationship among the figure:

${\mathrm{\θ}}_1={\tan }^{-1}\left(\frac{3h}{2\·\mathrm{OR}}\right)$ (formula 1)

${\mathrm{\α}}_1=\frac{\mathrm{\π}}{4}-\frac{1}{2}{\mathrm{\θ}}_1$ (formula 2)

The slope k of V-shaped groove section start ₁For:

k ₁=-tan α ₁(formula 3)

Can obtain by the geometric relationship among the figure again:

θ ₂=tan ^-1(h/RQ) (formula 1)

${\mathrm{\α}}_2=\frac{\mathrm{\π}}{2}-\frac{{\mathrm{\θ}}_1+{\mathrm{\θ}}_2}{2}$ (formula 2)

Thus, can draw the slope of locating at the V-shaped groove end is:

$k_2=\tan (\frac{\mathrm{\π}}{2}-({\mathrm{\θ}}_2+{\mathrm{\α}}_2))$ (formula 3)

If the width of V-shaped groove is P, P gets 15 μ m between the 50 μ m.Can be divided into a lot of infinitesimals that equate to V-shaped groove, every equal portions infinitesimal width is δ P, for example can define δ P=0.001mm.If certain on the V-shaped groove a bit with respect to coordinate of this V-shaped groove initial position R be (X, Y).Then V-shaped groove at the slope at this point place is:

$k=\tan ({\tan }^{-1}{k}_1+\frac{X}{P}({\tan }^{-1}{k}_2-{\tan }^{-1}{k}_1))$ (formula 4)

Coordinate according to the slope of this point can be calculated the next infinitesimal X of V-shaped groove, Y direction is respectively:

X=X+ δ P, Y=Y+ δ P * k (formula 5)

Can carry out the coordinate that every bit X, Y on the V-shaped groove of light guide plate somewhere are obtained in the integration pointwise to formula 8 with the integration iteration technique according to these relations, thereby draw the shape of this place's V-shaped groove.In fact, according to design of the present invention, also can adopt other progressive operational method to obtain the profile of V-shaped groove.According to the present invention, the degree of depth of V-shaped groove outline line is preferably between 6 μ m to 35 μ m.

Generally, the width minimum of V-shaped groove can for 15 μ m between the 50 μ m, can determine according to the size and the injection moulding precision of light guide plate, for example for the light guide plate of undersized mobile phone backlight module, its injection moulding precision can reach very high, and can design the V-shaped groove width is about 15 μ m.For large-sized backlight, the width of V-shaped groove can be suitably big, and to cut down finished cost, the size that still increases V-shaped groove can reduce brightness, so need comprehensive balance.

Below by the light guide plate with different structure being carried out ray machine Simulation result contrast, further specify the characteristics that the designing institute of optical plate of the present invention has.

Employing 2.5 * 0.85 * 0.8mm luminous intensity is that the paster LED of 800mcd carries out the ray machine simulation to the light guide plate of three kinds of different structures respectively, and the software of simulation usefulness is the Tracepro of Infotech.In the simulation process, place one deck reflectivity below the light guide plate and be 95% reflector plate, do not add diffusion sheet and brightness enhancement film above, only added one deck film viewing screen, so that light guide plate is carried out photometric analysis.

Fig. 5 A is for when light guide plate being a tabula rasa and the upper and lower surface 3D model all without any microstructure the time; Fig. 5 B is the intensity map of light guide plate among Fig. 5 A.From Fig. 5 A and 5B as can be seen brightness all concentrate on LED one side.Because the total reflection of light guide plate inside, light almost penetrates from the upper surface of light guide plate, but has fallen from the rear end face output loss away from the position of LED.

Fig. 6 A is for having only lower surface to be provided with the 3D model of microlens array when light guide plate; Fig. 6 B is the intensity map of light guide plate among Fig. 6 A.The arrangement mode of microlens array is that 45 degree are staggered, the directions X arrangement pitches is 0.6mm among the figure, the spacing that the Z direction is arranged is 0.3mm, the lenticule size is from radius of curvature R=0.24mm, depth d=0.015mm, diameter D=0.167033mm fades to radius of curvature R=0.6mm along Z direction equal difference, depth d=0.03mm, diameter D=0.3747mm.Lenticular change in depth is in the working ability scope that Precitech Nanoform 200 single-point diamond turning sharp knife feed systems are limited.Analog result shows that the brightness of light guide plate is at 1500nt (cd/m ²) about, near near the LED speck is arranged slightly, if reach homogeneity 〉=85%, brightness reaches 35000nt, then must add last layer diffusion sheet and double-deck BEF.

3D model when Fig. 7 A is the V-shaped groove structure of profile gradual change for be provided with microlens array and upper surface when the light guide plate lower surface; Fig. 7 B is the intensity map of light guide plate among Fig. 7 A.The microlens array of light guide plate distribute with Fig. 6 A in the same, the width of V-shaped groove structure is 30 μ m, and is more reasonable for the luminous intensity distribution that makes light guide plate, reaches uniform illumination and distributes, the profile of each V-shaped groove all calculates according to the boundary rays principle, and the distance between V-shaped groove also will adjust slightly.

Because the boundary rays principle has been adopted in the design of free form surface, so the luminous intensity distribution homogeneity of light guide plate can be improved greatly.In addition because the V-shaped groove structure of light guide plate upper surface has increased light round-robin number of times in light guide plate, so the effective rate of utilization of luminous energy will be improved widely.But, if it all is the same V-shaped groove structure that the light guide plate upper surface adopts shape, the diffraction of V-shaped groove is easy to produce the bright striped that secretly replaces that is similar to Moire fringe so, and it can cause the luminous intensity distribution homogeneity of light guide plate to descend, and is that each backlight manufacturer abstains from.Therefore, the distance between V-shaped groove need adjust slightly.Generally speaking, from the nearer place of led light source, it is big that the spacing of V-shaped groove is wanted, and promptly V-shaped groove is arranged rarelyr; And less away from led light source V-shaped groove gap ratio, promptly V-shaped groove row must be closeer.The closeest place, the spacing of V-shaped groove is about the twice of V-shaped groove width.For the medium-sized little light guide plate of one-inch, maximum V-shaped groove spacing can be more than 6 times or 7 times of minimum spacing.

The brightness of the light guide plate of analog result demonstration " the V-shaped groove structure of microlens array+profile gradual change " is at 3500nt (cd/m ²) about, to eliminate basically near the speck of LED, homogeneity also improves greatly, and near 90%, brightness has reached 35000nt, has reached basic demand.Compare with the light guide plate shown in Fig. 6 A, can use one deck BEF less when using light guide plate among Fig. 7 A to produce backlight module, only need add diffusion sheet and one deck intersection BEF (Cross BEF) or DBEF and the spread angle of the emergent ray of light guide plate effectively is controlled within the angular range that liquid crystal board accepts gets final product.

The job operation of the microlens array of light guide plate of the present invention and V-shaped groove structure has varied, generally can adopt chemical corrosion (Chemical Etching), methods such as photoetching (Optical Lithography) and single-point diamond turning.

But because the surfaceness of chemical corrosion and photoetching is not good enough, the loss ratio of luminous energy is bigger, so the preferred method of ultraprecise single-point diamond turning (Diamond Turning) that adopts is carried out the processing of light guide plate.

Single-point diamond turning is because its surfaceness can reach several nanometers, so also cry nanoprocessing.The core rod of the general aspheric processing of plastic cement, the injection mo(u)lding of plastic cement aspheric surface all is the method that adopts single-point diamond turning, also has some infrared single crystal body materials, resembles monocrystalline silicon, and monocrystalline germanium etc. also can be processed with the method for single-point diamond turning.Surface after the single-point diamond turning is an optical surface, does not need polishing.

The microlens array of light guide plate disposes the sharp knife feed system again by ultraprecise single-point diamond equipment and processes, and for example can use Nanoform 200 diaxon ultraprecise process equipments.The light guide plate core rod is fixed on the revolving shaft rotates, utilize the quick piezoelectricity feeding (Fast Tool Serve) of the diamond bit protruding or recessed lens arra of sending a car out.The ultraprecise processing of the free form surface of V-shaped groove can be adopted five large-scale ultraprecise process equipments (for example five Free-Form Surface Machining equipment of Freeform 705G).Wherein, because five ultraprecise process equipments need be according to the X of wheel for inputting profile each point in the single-point diamond grinding, the Y coordinate data is processed, so required process time is longer, thereby processing cost is more expensive.The free form surface of V-shaped groove is if adopt the method for single-point diamond grinding, and then the processing of V-shaped groove structure can not be subjected to the restriction of the V-shaped groove degree of depth.

Based on above-mentioned explanation, the present invention mainly provides a kind of design of light guide plate of backlight module, and its one side is the V-shaped groove structure of profile gradual change for microlens array structure another side.Because the boundary rays principle has been adopted in the design of the free form surface of V-shaped groove structure, so the luminous intensity distribution homogeneity of light guide plate can be improved greatly, makes the luminous intensity distribution of light guide plate more reasonable.And the structure of V-shaped groove increased the cycle index of light in light guide plate inside, improved the utilization factor of luminous energy greatly.Adopt light guide plate of the present invention, illumination will will exceed about one times than the light guide plate of having only the site.At least one deck brightness enhancement film can be used less in the backlight module, cost can be effectively reduced.In addition, can also design the light guide plate of backlight module like this, even its two sides is the V-shaped groove structure of profile gradual change.In addition, in order to ensure the machining precision of V-shaped groove and microlens array, turning of ultraprecise single-point diamond and grinding technique are preferred.

Claims (9)

1. light guide plate that is used for backlight module, it is characterized in that, the upper surface of this light guide plate is a plurality of V-shaped groove structures, described V-shaped groove structure has the free form surface of profile gradual change, the lower surface of this light guide plate is lattice point structure or arranges webbed micro structure array, wherein, if the tangent slope at the outline line top of this V-shaped groove structure is k ₁, the tangent slope of the outline line bottom of this V-shaped groove structure is k ₂, the width of this V-shaped groove structure is P, is that (X, the tangent slope k that Y) locates passes through formula for other all coordinate points of initial point with the top end of the outline line of this V-shaped groove structure in the outline line of this V-shaped groove structure then $k=\tan ({\tan }^{-1}{k}_1+\frac{X}{P}({\tan }^{-1}{k}_2-{\tan }^{-1}{k}_1))$ Obtain.

2. light guide plate as claimed in claim 1 is characterized in that, described backlight module adopts the mode of edge light, and wherein led light source is positioned over a side of this light guide plate, and light advances this light guide plate from the side coupling of this light guide plate.

3. light guide plate as claimed in claim 2, it is characterized in that, described V-shaped groove is the curved surface of a profile gradual change towards the one side of led light source, another side is vertically or the plane of near vertical, at the horizontal sextant angle of the tangent line of the curved surface profile line at V-shaped groove top greater than horizontal sextant angle at the tangent line of the curved surface profile line of the bottom of V-shaped groove.

4. light guide plate as claimed in claim 1 is characterized in that, between the 50 μ m, the degree of depth is between 6 μ m to 35 μ m at 15 μ m for the width of described V-shaped groove.

5. light guide plate as claimed in claim 1 is characterized in that, the lower surface of described light guide plate is provided with lines up netted microlens array.

6. light guide plate as claimed in claim 5 is characterized in that, described lenticule is semicircle sphere, oval sphere, taper shape or Square-edge taper.

7. light guide plate as claimed in claim 1 is characterized in that, the spacing of each adjacent V-shaped groove of contiguous led light source place of described upper surface is greater than the spacing away from each adjacent V-shaped groove of led light source place.

8. light guide plate as claimed in claim 1 is characterized in that described light guide plate is the light guide plate of backlight module, is used for the back lighting of handheld devices, LCD computer display, LCD TV, pick-up unit.

9. backlight module, include reflector plate, led light source and diffusion sheet successively, it is characterized in that, between described reflector plate and diffusion sheet, also be provided with as each described light guide plate among the claim 1-8, described backlight module adopts the mode of edge light, and wherein said light guide plate has the surface of V-shaped groove structure towards this diffusion sheet.

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