WO1998053608A1 - Contrast improvement in liquid crystal light valve projectors - Google Patents
Contrast improvement in liquid crystal light valve projectors Download PDFInfo
- Publication number
- WO1998053608A1 WO1998053608A1 PCT/BE1998/000073 BE9800073W WO9853608A1 WO 1998053608 A1 WO1998053608 A1 WO 1998053608A1 BE 9800073 W BE9800073 W BE 9800073W WO 9853608 A1 WO9853608 A1 WO 9853608A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- lcd
- angle
- polariser
- analyser
- projector
- Prior art date
Links
Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
- G02F1/1333—Constructional arrangements; Manufacturing methods
- G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
- G02F1/133528—Polarisers
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N5/00—Details of television systems
- H04N5/74—Projection arrangements for image reproduction, e.g. using eidophor
Definitions
- the present invention relates to contrast improvement in liquid crystal light valve projection systems, more particularly to a light valve image projector with a disposition for improving the contrast of the by that projector projected optical image.
- An appropriate light valve for such a projection system is a liquid crystal display, commonly referred to as an "LCD" .
- Fig. 1 shows the optical path in an OFF-axis projection system.
- Said projection system comprises an OFF-axis projector 1 and a screen 2.
- the OFF-axis projector 1 comprises an illumination system 3, a field lens 4, a polariser 5, an LCD 6, an analyser 7 and a projection lens 8.
- the illumination system 3 comprises a lamp, a reflector, and an integrating system which converts the circular and non-uniform light distribution coming from the reflector into a rectangular and uniform illumination of the LCD 6.
- the field lens 4 images the illumination system into the entrance pupil of the projection lens 8. In this way, it ensures that the light with which the LCD 6 is illuminated is directed into this entrance pupil of the projection lens 8.
- the projection lens 8 images the illuminated LCD 6 on the screen 2.
- the line through the optical centres of the illumination system 3, the field lens 4 and the projection lens 8 is further called the optical axis 9 of the projector 1.
- the OFF-axis projector 1 is a multi-light valve projector (for example a projector with three light valves)
- the optical path is more complex, because by means of a set of dichroic mirrors the light is splitted into 3 colours (red, green and blue) , and after modulation of the light, these colours are recombined again.
- the OFF-axis projector then comprises an illumination system, three field lenses, three sets consisting of a polariser, an LCD and an analyser, and a projection lens.
- a line through the optical centres of the illumination system, one of the field lenses and the projection lens is an optical axis of the projector.
- the schematic description of the illumination and imaging system shown in figure 1 is not altered by these colour-splitting mirrors. In what follows the state of the art is described as if there were only one illumination system, one field lens, one set consisting of a polariser, an LCD and an analyser, and one projection lens.
- the direction of the optical axis 9 of the projector 1 is different from the direction of the optical axis 10 of the projection lens 8.
- Both optical axes 9 and 10 include an OFF-axis angle ⁇ as shown in Fig. 1.
- This angle ⁇ can have any positive value, but in the most common OFF-axis configuration, the projector 1 is set up in such a way that the optical axis 10 of the projection lens 8 intersects with the bottom of the image of the screen 2.
- Fig. 10a shows the minimum configuration of an ON-axis liquid crystal light valve projection system. It comprises an ON-axis projector 11 and a screen 2.
- the ON- axis projector 11 comprises the same parts as the OFF-axis projector 1 described hereinabove. Said same parts have been denoted by means of the same reference numerals.
- Fig. 2 shows an image source of as well OFF-axis and ON-axis liquid crystal light valve projectors 1 and 11.
- Said image source comprises a polariser 5, an LCD 6 and an analyser 7.
- the polariser 5 and the analyser 7 are both light polarising elements and have in their planes each an absorbing direction and a non-absorbing direction, the absorbing direction being perpendicular to the non-absorbing direction.
- the LCD 6 comprises, with reference to the light direction, a front glass plate 15, a back glass plate 16 and sealed in between both glass plates 15, 16 a twisted nematic liquid crystal layer.
- the twisted nematic LCD (TN-LCD) may be addressed with an active matrix.
- a switching device such as a thin film transistor or a number of thin film diodes, is integrated on each pixel.
- the non-absorbing direction 17 of the polariser 5 is perpendicular to the rubbing direction 18 of the front glass plate 15 of the LCD 6.
- Said rubbing direction 18 defines the preferred direction of the liquid crystal molecules at the interface with the front glass plate 15.
- the non-absorbing direction 19 of the analyser 7 is perpendicular to the rubbing direction 20 of the back glass plate 16.
- Fig. 3a shows the distribution of the molecules 21 in a twisted nematic LCD between the front glass plate 15 and the rear glass plate 16 in the bright state.
- Fig. 3b shows the corresponding distribution in the dark state.
- the non-absorbing directions of these three elements must be correctly matched.
- the analyser or the polariser may be installed rotatable around their normal.
- Fig. 4 shows the typical viewing angle characteristics of a twisted nematic LCD.
- the graphs are lines of equal contrast between the bright and dark state at the two corresponding driving voltages, with relative values between 3 en 300.
- the vertical axis shows the vertical angle of incidence between -40° and 40°. It presents the component of the light ray within the plane perpendicular to both the plane of the LCD and the horizontal image scanning direction of the LCD.
- the horizontal axis gives angles of incidence between -40° and 40° and is the component of the light ray within the plane perpendicular to the plane of the LCD and the vertical image scanning direction of the LCD.
- Fig. 4 thus demonstrates the dependence of the contrast in function of the incident angle of the light which enters the LCD.
- the LCD light transmission (vertical axis) depends on the angle of incidence (different graphs) and on the LCD drive voltage (horizontal axis) .
- the light transmission graphs show a minimum. This minimum determines the maximum obtainable contrast at that angle of incidence, as for higher drive voltages the contrast is negative.
- the minimum transmission value is higher and so the maximum obtainable contrast is lower.
- the location of the minimum on the graph is shifted to a higher drive voltage and to a lower transmission value or higher obtainable contrast.
- zero and negative angles of incidence of light there is no minimum of transmission.
- FIG. 6a shows the intensity measured at the top of the display screen
- Fig. 6b shows the intensity in the middle of the screen
- Fig. 6c shows the intensity measured at the bottom of the screen.
- Fig. 6a shows that in areas of the image where the angle of incidence of light is larger, the intensity of the projected image has a minimum value for a specific drive voltage of the LCD. This is the case at the top of the image in a projection system as illustrated in Fig. 1. For drive voltages above the voltage of minimum intensity, the contrast is even negative. If otherwise the drive voltage should be equal all over the LCD, such an intensity minimum will appear on the screen at a specific angle of incidence and be visible as horizontal darker bar.
- Fig. 6b and Fig. 6c show that in areas of the image where the angle of incidence is smaller, such a minimum of intensity (or in other words maximum of contrast) does not occur. There, the limitation is determined by the maximum LCD drive voltage allowed.
- the LCD drive voltages are chosen so as to get a uniform black level or minimum intensity all over the screen.
- the limit is thereby determined by what can be obtained in the area of larger angles of incidence, and so does not result in the best contrast possible in other areas of the screen.
- a quarter-wave compensator plate is disposed between the polariser and the liquid crystal light. This solution is only suitable for the reflective set-up described in the patent and is not applicable for projection with TN-LCDs .
- a stop is disposed inside the projection lens, forming an aperture of the lens assembly decentered from the optical axis of the lenses of the projection lens assembly in the vertical scanning direction of the liquid crystal panel. The blocking of the light rays at the entrance pupil of the lens reduces the efficiency of the projection system, resulting in a lower light output of the projector.
- a light valve image projector provided with a disposition for improving the contrast of a by that projector projected optical image.
- the projector comprises at least one illumination system, at least one field lens, at least one set consisting of a polariser, an LCD and an analyser, and at least one projection lens. It presents at least one optical axis, each optical axis of the projector including an angle ⁇ with the optical axis of the projection lenses.
- At least one of the analysers includes with the LCD of the same set, consisting of polariser, LCD and analyser, an angle ⁇ a larger than the angle ⁇ , at least for the light rays that pass through the contrast limiting area of said LCD.
- the angle ⁇ a is so that said at least one of the analysers is not parallel to the polariser belonging to the same set consisting of analyser, LCD and polariser, at least for the light rays that pass through the contrast limiting area of the LCD.
- the contrast limiting area of an LCD included in a light valve image projector is defined as the part of the surface of the LCD through which light rays pass at that angle with the LCD for which the highest obtainable contrast is minimum.
- the projector may be a monochrome projector or a multicolour projector.
- the angles ⁇ a included by each analyser with the corresponding LCD of the same set may be different.
- At least one of the polarisers includes an angle ⁇ p with the LCD of the same set consisting of polariser, LCD and analyser. This angle is larger than the angle ⁇ , at least for the light rays that pass through the contrast limiting area of said LCD.
- the angles ⁇ p included by each polariser with the corresponding LCD of the same set may be different. If the angle mentioned hereinabove is different from zero, the projector is called an OFF-axis projector.
- the projector is called an ON-axis projector.
- at least one of the analysers of the projector has a flat surface.
- At least one of the analysers is curved.
- it has a curvature such that the tangent planes of said analyser at the points of incidence of the light rays which pass through the contrast limiting area of the LCD of the same set, include an angle ⁇ a > ⁇ with the plane of the LCD.
- At least one of the polarisers has a flat surface.
- At least one of the polarisers is curved. In that case it has a curvature such that the tangent planes of said polariser at the points of incidence of the light rays passing through the contrast limiting area of the LCD of the same set, include an angle ⁇ p > ⁇ with the plane of the LCD.
- Analyser (s) and polariser (s) may be movable such that the angles ⁇ a and/or ⁇ p can be adjusted by the manufacturer and/or by the user.
- a specific embodiment of the present invention is a projector comprising one illumination system, three field lenses, three sets consisting of a polariser, an LCD and an analyser, and one projection lens.
- Fig. 1 shows the optical path in an OFF-axis projection system (prior art) ;
- Fig. 2 shows the non-absorbing directions of the polariser and the analyser as they are mounted in a conventional way in a liquid crystal light valve projector (prior art) ;
- Fig. 3a and Fig. 3b show the molecule distribution in a twisted nematic liquid crystal display (prior art) ;
- Fig. 4 shows simulated viewing angle characteristics with iso- contrast curves for incident angles of light on an LCD (prior art);
- Fig. 5 shows the light transmission in function of the drive voltage and for different angles of light incidence (prior art);
- Fig. 6a, Fig. 6b and Fig. 6c show the normalised intensity of an image projected by an OFF-axis projector in function of the drive voltage applied to the LCD, respectively at the top, in the middle and at the bottom of the screen;
- Fig. 7a, Fig. 7b and Fig. 7c show the normalised intensity of an image projected by an ON-axis projector in function of the drive voltage applied to the LCD, respectively at the top, in the middle and at the bottom of the screen;
- Fig. 8a shows an OFF-axis projection system wherein the angle between the analyser and the LCD is larger than the OFF-axis angle
- Fig. 8b shows an OFF-axis projector wherein the angle between the analyser and the LCD and the angle between the polariser and the LCD are larger than the OFF-axis angle;
- Fig. 9 shows an OFF-axis projector wherein the analyser and the polariser have a curved surface
- Fig. 10a shows the optical path in an ON-axis projection system (prior art)
- Fig. 10b shows an ON-axis projector wherein the angle between the analyser and the LCD and the angle between the polariser and the LCD are larger than 0• ;
- Fig. 11 shows an ON-axis projector wherein the analyser and the polariser have a curved surface.
- FIG. 8a A first embodiment of the present invention is shown in Fig. 8a. It presents an OFF-axis projector 22, wherein the angle ⁇ a between the analyser 23 and the LCD 6 is made larger than the OFF- axis angle ⁇ .
- the polariser 5 is perpendicular to the optical axis of the projector 9 and includes an angle to the LCD 6, which is equal to the OFF-axis angle ⁇ .
- Fig. 6a, Fig. 6b and Fig. 6c show the normalised intensity of an image projected by the OFF-axis projector, in function of the drive voltage applied to the LCD, at the top, in the middle and at the bottom of the screen respectively.
- the graphs marked "0" correspond to the prior art OFF-axis projection system, whereby the polariser and the analyser are mounted perpendicular to the optical axis of the projector, or in other words have an angle to the LCD surface equal to the OFF-axis angle ⁇ .
- the graph marked "A” corresponds to the set-up covered by this invention and described in this first embodiment, whereby the angle ⁇ a between the analyser and the LCD is larger than the OFF-axis angle ⁇ .
- the contrast is improved over the whole screen, as illustrated in the three drawings Fig. 6a, Fig. 6b and Fig. 6c, wherein the graphs "A* show lower values of intensity compared to the graphs *0".
- the result is that in the area which determines the minimum of contrast being the top of the screen, the contrast is increased compared to the prior art version.
- the contrast in the other areas being the middle and the top of the screen is also improved in a way that the overall contrast compromise is improved compared to the prior art version.
- FIG. 8b A second embodiment of the present invention is shown in Fig. 8b. It presents an OFF-axis projector 24 wherein the angle ⁇ a between the analyser 25 and the LCD 6 is made larger than the OFF- axis angle ⁇ .
- the angle ⁇ p between the polariser 26 and the LCD 6 is larger than the OFF-axis angle ⁇ .
- the graphs "B" in Fig. 6a, Fig. 6b and Fig. 6c show the improvement of the contrast of the image obtained by means of the decrease of the lower intensity levels in function of the LCD drive voltage, compared to the lower intensity levels for the prior art OFF-axis projection system (graphs "0") and to the intensity for the first embodiment OFF-axis projector (graphs "A").
- the second embodiment has a decreased, or in other words improved, black level at the top, in the middle and at the bottom of the screen.
- Having the polariser mounted including an angle to the LCD which is larger than the OFF-axis angle ⁇ improves even more the over all black level of the projector and permits to obtain the highest possible contrast all over the screen.
- FIG. 10b Another embodiment of the present invention is shown in Fig. 10b.
- the angle ⁇ a between the analyser 28 and the LCD 6 as well as the angle ⁇ p between the polariser 29 and the LCD 6 are made larger than 0 degrees .
- Fig. 7a, Fig. 7b and Fig. 7c show the normalised intensity of an image projected by the ON-axis liquid crystal light valve projector in function of the drive voltage applied to the LCD, at the top, in the middle and at the bottom of the screen respectively.
- the graph marked "0* corresponds to the prior art projection system whereby the polariser and the analyser are mounted perpendicular to the optical axis of the projector, or in other words are parallel to the LCD.
- the graph marked "A* corresponds to the ON-AXIS projection system whereby the angle ⁇ a between the analyser and the LCD is different from zero, and whereby the angle ⁇ p between the polariser and the LCD is equal to zero.
- the graph marked "B” corresponds to the ON-AXIS projection system whereby both the angles ⁇ and ⁇ p are different from zero.
- Fig. 7a, 7b and 7c show that the ON-axis projector has a lower contrast at the bottom of the screen, because the lower intensity values are higher there than at the top of the screen.
- the bottom of the screen corresponds to the top of the LCD where incident light rays have a negative incident angle.
- the viewing angle characteristics of Fig. 4 which show lower contrast for negative incident angles of light, explain that the contrast is lower and thus most critical at the bottom of the image in the ON-axis projection system.
- Fig. 9 and Fig. 11 Other embodiments of the present invention are shown in Fig. 9 and Fig. 11. In these embodiments, the surfaces of the analyser and polariser are not flat but curved.
- the curved versions of analyser and polariser introduce a gradually enlarging angle to the LCD plane, the angle being largest at the contrast limiting area side of the LCD.
- the curvatures of the surfaces of analyser and polariser do not decrease the contrast uniformity of the projection system, as long as the angle between the analyser or polariser on the one hand, and the plane of the LCD on the other hand, has its largest value facing the contrast limiting area side of the LCD, and is in the other areas large enough to permit the compensation of the contrast by adaptation of the drive voltage there.
- This is explained by the following.
- the overall contrast is limited to the contrast which can be obtained in the area where the contrast has a minimum in function of the drive voltage as made clear in Fig. 5.
- the contrast improvement obtained by an embodiment of the present invention must be maximum at that contrast limiting area and can be smaller in other areas as there it can be compensated by adaptation of the drive voltage.
- Fig. 9 shows a schematic view of an OFF-axis projector 30, whereby the analyser 31 and polariser 32 have a curved surface.
- the largest curvature corresponds to the bottom side of the LCD 6, which is the LCD side with the contrast limiting area.
- the angle ⁇ a is the angle between the LCD plane and the tangent plane 38 to the curved analyser 31 at a point of incidence of a light ray.
- ⁇ a is larger than ⁇ for light rays passing through the contrast limiting area of the LCD 6.
- the angle ⁇ is the angle between the LCD plane and the tangent plane 39 to the curved analyser 32 at a point of incidence of a light ray.
- ⁇ p is larger than ⁇ for light rays passing through the contrast limiting area of the LCD 6.
- Fig. 11 shows a schematic view of an ON-axis projector, whereby the analyser 34 and polariser 35 have a curved surface.
- the largest curvature corresponds to the topside of the LCD 6, which is the LCD side with the contrast limiting area.
- the angle ⁇ a is the angle between the LCD plane and the tangent plane 36 to the curved analyser 34 at a point of incidence of a light ray.
- ⁇ a is larger than zero for light rays passing through the contrast limiting area of the LCD.
- the angle ⁇ p is the angle between the LCD plane and the tangent plane 37 to the curved analyser 35 at a point of incidence of a light ray.
- ⁇ p is larger than zero for light rays passing through the contrast limiting area of the LCD 6.
- Fig. 8a, 8b and 9 describe OFF-axis projectors whereby the projection lens is positioned at a height lower than the middle of the screen. This applies to what is usually called a table-mounted projector.
- the present invention also applies to OFF-axis projectors whereby the position of the projection lens is higher than the height of screen. This applies to what is usually called a ceiling mounted projector.
- a ceiling mounted projector For a ceiling mounted projector, the figures Fig. 8a, 8b and 9 do apply but should be mirrored vertically, and what is stated about the top of the screen then counts for the bottom of the screen, and vice versa.
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- Physics & Mathematics (AREA)
- Nonlinear Science (AREA)
- Crystallography & Structural Chemistry (AREA)
- Signal Processing (AREA)
- Mathematical Physics (AREA)
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Multimedia (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Projection Apparatus (AREA)
- Liquid Crystal (AREA)
- Video Image Reproduction Devices For Color Tv Systems (AREA)
- Transforming Electric Information Into Light Information (AREA)
- Polarising Elements (AREA)
Abstract
Description
Claims
Priority Applications (5)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
CA002290686A CA2290686C (en) | 1997-05-20 | 1998-05-20 | Contrast improvement in liquid crystal light valve projectors |
AU74192/98A AU7419298A (en) | 1997-05-20 | 1998-05-20 | Contrast improvement in liquid crystal light valve projectors |
JP54972098A JP2001526801A (en) | 1997-05-20 | 1998-05-20 | Improvement of contrast in liquid crystal light valve projector |
US09/438,381 US6224215B1 (en) | 1997-05-20 | 1999-11-12 | Contrast improvement in liquid crystal light valve projectors |
NO995597A NO316578B1 (en) | 1997-05-20 | 1999-11-15 | Contrast enhancement in liquid crystal light projectors |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP97870070.6 | 1997-05-20 | ||
EP97870070A EP0880279B1 (en) | 1997-05-20 | 1997-05-20 | Contrast improvement in liquid crystal light valve projectors |
Related Child Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US09/438,381 Continuation US6224215B1 (en) | 1997-05-20 | 1999-11-12 | Contrast improvement in liquid crystal light valve projectors |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1998053608A1 true WO1998053608A1 (en) | 1998-11-26 |
Family
ID=8231001
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/BE1998/000073 WO1998053608A1 (en) | 1997-05-20 | 1998-05-20 | Contrast improvement in liquid crystal light valve projectors |
Country Status (9)
Country | Link |
---|---|
US (1) | US6224215B1 (en) |
EP (1) | EP0880279B1 (en) |
JP (1) | JP2001526801A (en) |
AT (1) | ATE203867T1 (en) |
AU (1) | AU7419298A (en) |
CA (1) | CA2290686C (en) |
DE (1) | DE69705932T2 (en) |
NO (1) | NO316578B1 (en) |
WO (1) | WO1998053608A1 (en) |
Families Citing this family (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP4493113B2 (en) * | 1999-01-29 | 2010-06-30 | 株式会社リコー | Projector and projection image correction apparatus |
KR100441162B1 (en) * | 2000-01-28 | 2004-07-21 | 세이코 엡슨 가부시키가이샤 | Light reflective type polarizer and projector using the same |
US6669343B2 (en) | 2001-05-31 | 2003-12-30 | Koninklijke Philips Electronics N.V. | Image display system |
WO2006026320A2 (en) | 2004-08-26 | 2006-03-09 | Be Seen! Solutions, Inc. | Image projector display device |
US7204599B2 (en) * | 2004-12-16 | 2007-04-17 | Hewlett-Packard Development Company, L.P. | Offset projection system |
US20060181552A1 (en) * | 2005-02-11 | 2006-08-17 | Siemens Medical Solutions Usa, Inc. | Image display calibration for ultrasound and other systems |
US20080122996A1 (en) * | 2006-11-29 | 2008-05-29 | Nano Loa, Inc. | Off-axis projection system |
JP4441891B2 (en) * | 2007-03-22 | 2010-03-31 | カシオ計算機株式会社 | Projection device |
JP6170554B2 (en) * | 2012-07-01 | 2017-07-26 | バルコ・ナムローゼ・フエンノートシャップ | Projector optics |
CN110933266B (en) * | 2019-07-15 | 2021-12-21 | 华为技术有限公司 | Image pickup apparatus, method and adjustment element |
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EP0409246A2 (en) * | 1989-07-20 | 1991-01-23 | Sanyo Electric Co., Ltd. | Liquid crystal projector |
JPH0371110A (en) * | 1989-08-11 | 1991-03-26 | Sanyo Electric Co Ltd | Liquid crystal projector |
US5371559A (en) * | 1991-11-15 | 1994-12-06 | Matsushita Electric Industrial Co., Ltd. | Light valve image projection apparatus |
JPH07234401A (en) * | 1994-02-24 | 1995-09-05 | Fujitsu Ltd | Projection type liquid crystal display |
Family Cites Families (10)
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US5220363A (en) * | 1988-09-14 | 1993-06-15 | Casio Computer Co., Ltd. | Projector |
JPH037110A (en) | 1989-06-02 | 1991-01-14 | Yamaha Corp | Bed with head board |
US5422691A (en) * | 1991-03-15 | 1995-06-06 | Seiko Epson Corporation | Projection type displaying apparatus and illumination system |
FR2693020B1 (en) | 1992-06-26 | 1999-01-22 | Thomson Consumer Electronics | NEMATIC LIQUID CRYSTAL DISPLAY DEVICE. |
JP3320862B2 (en) * | 1992-11-26 | 2002-09-03 | 旭光学工業株式会社 | Pupil conjugate coupling device for projection optical system |
US5355188A (en) * | 1993-09-09 | 1994-10-11 | In Focus Systems, Inc. | Method and apparatus for distortion correction in optical projectors |
US5576854A (en) | 1993-11-12 | 1996-11-19 | Hughes-Jvc Technology Corporation | Liquid crystal light valve projector with improved contrast ratio and with 0.27 wavelength compensation for birefringence in the liquid crystal light valve |
US5820240A (en) * | 1995-06-22 | 1998-10-13 | Minolta Co., Ltd. | Projection optical device |
JP3138189B2 (en) * | 1995-07-28 | 2001-02-26 | シャープ株式会社 | Projection type liquid crystal display |
US5622417A (en) * | 1995-11-01 | 1997-04-22 | Lightware, Inc. | Invertible and orthoscopic liquid crystal display projector |
-
1997
- 1997-05-20 AT AT97870070T patent/ATE203867T1/en not_active IP Right Cessation
- 1997-05-20 EP EP97870070A patent/EP0880279B1/en not_active Expired - Lifetime
- 1997-05-20 DE DE69705932T patent/DE69705932T2/en not_active Expired - Fee Related
-
1998
- 1998-05-20 JP JP54972098A patent/JP2001526801A/en active Pending
- 1998-05-20 WO PCT/BE1998/000073 patent/WO1998053608A1/en active Application Filing
- 1998-05-20 CA CA002290686A patent/CA2290686C/en not_active Expired - Fee Related
- 1998-05-20 AU AU74192/98A patent/AU7419298A/en not_active Abandoned
-
1999
- 1999-11-12 US US09/438,381 patent/US6224215B1/en not_active Expired - Lifetime
- 1999-11-15 NO NO995597A patent/NO316578B1/en unknown
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0409246A2 (en) * | 1989-07-20 | 1991-01-23 | Sanyo Electric Co., Ltd. | Liquid crystal projector |
JPH0371110A (en) * | 1989-08-11 | 1991-03-26 | Sanyo Electric Co Ltd | Liquid crystal projector |
US5371559A (en) * | 1991-11-15 | 1994-12-06 | Matsushita Electric Industrial Co., Ltd. | Light valve image projection apparatus |
JPH07234401A (en) * | 1994-02-24 | 1995-09-05 | Fujitsu Ltd | Projection type liquid crystal display |
Non-Patent Citations (2)
Title |
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PATENT ABSTRACTS OF JAPAN vol. 015, no. 234 (P - 1215) 14 June 1991 (1991-06-14) * |
PATENT ABSTRACTS OF JAPAN vol. 096, no. 001 31 January 1996 (1996-01-31) * |
Also Published As
Publication number | Publication date |
---|---|
EP0880279A1 (en) | 1998-11-25 |
JP2001526801A (en) | 2001-12-18 |
ATE203867T1 (en) | 2001-08-15 |
NO995597L (en) | 1999-11-15 |
NO316578B1 (en) | 2004-02-23 |
DE69705932D1 (en) | 2001-09-06 |
AU7419298A (en) | 1998-12-11 |
DE69705932T2 (en) | 2002-04-18 |
CA2290686C (en) | 2003-12-23 |
US6224215B1 (en) | 2001-05-01 |
NO995597D0 (en) | 1999-11-15 |
EP0880279B1 (en) | 2001-08-01 |
CA2290686A1 (en) | 1998-11-26 |
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