Electro-optical dithering system using birefringence for optical displays and method

• US 5,572,341 A
• Filed: 02/22/1995
• Issued: 11/05/1996
• Est. Priority Date: 10/25/1994
• Status: Expired due to Term

• Current Assignee: Fergason Patent Properties
• Original Assignee: James L. Fergason
• Inventors: Fergason, James L.
• Primary Examiner(s): Gross, Anita Pellman
• Assistant Examiner(s): TON, MINH TOAN T
• Application Number:
  US08/392,055
• Time in Patent Office: 622 Days
• Field of Search: 359/39, 359/94, 359/63, 359/464, 359/465, 359/93
• US Class Current: 349/200
• CPC Class Codes: G02B 5/3083 Birefringent or phase retarding elements G02B5/3008, G02B5/3016 take precedence; systems for polarisation control G02B27/286; manufacturing phase modulating patterns by lithographic processes G03F7/001
• CPC Class Codes: G02F 1/13363 Birefringent elements, e.g. for optical compensation
• CPC Class Codes: G02F 1/133638 Waveplates, i.e. plates with a retardation value of lambda/n
• CPC Class Codes: G02F 1/1347 Arrangement of liquid crystal layers or cells in which the final condition of one light beam is achieved by the addition of the effects of two or more layers or cells
• CPC Class Codes: G02F 2203/62 Switchable arrangements whereby the element being usually not switchable
• CPC Class Codes: G02F 2413/02 Number of plates being 2
• CPC Class Codes: G02F 2413/04 Number of plates greater than or equal to 4
• CPC Class Codes: G09G 2320/0626 for control of overall brightness
• CPC Class Codes: G09G 2360/144 the light being ambient light
• CPC Class Codes: H01J 2229/8926 Active components, e.g. LCD's, indicators, illuminators and moving devices
• CPC Class Codes: H01J 29/89 Optical or photographic arrangements structurally combined or co-operating with the vessel H01J29/866 and H01J29/868 take precedence
• CPC Class Codes: H04N 13/305 using lenticular lenses, e.g. arrangements of cylindrical lenses
• CPC Class Codes: H04N 13/31 using parallax barriers
• CPC Class Codes: H04N 13/324 Colour aspects
• CPC Class Codes: H04N 13/341 using temporal multiplexing
• CPC Class Codes: H04N 13/344 with head-mounted left-right displays
• CPC Class Codes: H04N 13/395 with depth sampling, i.e. the volume being constructed from a stack or sequence of 2D image planes
• CPC Class Codes: H04N 13/398 Synchronisation thereof; Control thereof
• CPC Class Codes: H04N 5/66 Transforming electric information into light information scanning details H04N3/00
• CPC Class Codes: H04N 5/7441 the modulator being an array of liquid crystal cells
• CPC Class Codes: H04N 5/7491 : of head mounted projectors
• CPC Class Codes: H04N 9/30 : using solid-state colour display devices
• CPC Class Codes: H04N 9/3102 : using two-dimensional electronic spatial light modulators micromechanical modulators as such G02B26/0833; liquid crystal modulators as such G02F1/13
• CPC Class Codes: H04N 9/3155 : for controlling the light source light source control per se H05B35/00 – H05B47/00; control of an illumination source for displays in general G09G3/3406
• CPC Class Codes: H04N 9/3167 : for polarizing the light beam polarizing optical systems per se G02B27/28
• CPC Class Codes: H04N 9/3173 : wherein the projection device is specially adapted for enhanced portability
• CPC Class Codes: H04N 9/3188 : Scale or resolution adjustment scaling in general G06T3/40; resolution modifying circuits for displays in general G09G5/391

Abstract

An electro-optical dithering system based on birefringence or double refraction increases the resolution of a display and includes a birefringent material, such as a calcite material, which selectively refracts or deflects light depending on an optical polarization characteristic of the light, and a switch to switch the optical polarization characteristic of the light, thereby to determine the location of output optical information. Thus, the apparatus and method of the invention can change the location of an optical signal, and the change can be used for a number of purposes, such as to improve resolution of a display, to provide an auto-stereoscopic output, to interlace optical signals, to facilitate locating and hiding of circuitry, to facilitate overlapping of tiles or pixels, etc.

Claims

1. Apparatus for shifting an optical signal, comprising

double refraction means for refracting an optical signal based on a characteristic of such optical signal to change the direction of the optical signal,

means for changing such characteristic to determine whether such direction is changed, and

said double refraction means comprising liquid crystal material.

2. The apparatus of claim 1, said liquid crystal material comprising liquid crystal polymer.

3. Apparatus for shifting an optical signal, comprising

double refraction means for refracting an optical signal based on a characteristic of such optical signal to change the direction of the optical signal,

means for changing such characteristic to determine whether such direction is changed, and

said double refraction means comprising liquid crystal material, and said means for changing comprising means for changing a characteristic of the liquid crystal material relative to the optical signal incident thereon thereby effectively to change such characteristic of the optical signal relative to such double refraction means.

4. The apparatus of claim 3, said means for changing comprising means for changing alignment of liquid crystal material relative to transmission direction of light transmitted therethrough.

5. Apparatus for shifting an optical signal, comprising

double refraction means for refracting an optical signal based on a characteristic of such optical signal to change the direction of the optical signal,

means for changing such characteristic to determine whether such direction is changed,

said double refraction means and changing means comprising means for selectively changing the location of an optical output signal between plural locations,

said double refraction means and changing means comprising means for selectively changing the location of an optical output signal between plural locations located on plural respective axes, and

said double refraction means and changing means comprising means for selectively changing the location of an optical output signal between plural locations located on plural respective non-parallel axes.

6. An optical display system comprising an optical display and the apparatus of claim 5, said apparatus being positioned relative to the optical display selectively and sequentially to change the location of optical output signals from the display to enhance the resolution of the display.

7. The system of claim 6, said optical display comprising a CRT.

8. The system of claim 6, said optical display comprising an LCD.

9. The system of claim 8, said LCD comprising an active matrix LCD.

10. The apparatus of claim 5, wherein the direction of the optical signal emitted from said double refracting means is parallel to the direction of the optical signal received by said double refracting means.

11. The apparatus of claim 5, wherein said double refraction means shifts or does not shift the optical signal based on the polarization characteristics of the optical signal.

12. Apparatus for shifting an optical signal, comprising

double refraction means for refracting an optical signal based on a characteristic of such optical signal to change the direction of the optical signal,

means for changing such characteristic to determine whether such direction is changed,

said double refraction means and changing means comprising means for selectively changing the location of an optical output signal between plural locations,

said double refraction means and changing means comprising means for selectively changing the location of an optical output signal between plural locations located on plural respective axes, and

said double refraction means and changing means comprising means for selectively changing the location of an optical output signal between plural locations located on plural respective orthogonal axes.

13. A method of covering optical dead space in an optical display, comprising

providing a plurality of optical signals output from an optical display with optical dead space between respective optical signals,

selectively refracting respective optical signals based on a characteristic of such optical signals to change the direction of the optical signal, and

selectively changing such characteristic to determine whether such direction is changed thereby to determine the location of the output optical signals to cover such optical dead space.

14. An optical display system, comprising:

a display for displaying optical information in the form of plural spaced pixels; and

means for selectively shifting light emitted from said display based on a polarization characteristic of the light, the shifted light being shifted a distance less than or equal to the space between adjacent said spaced pixels.

15. The display system of claim 14, wherein said display is an active matrix liquid crystal display.

16. The display system of claim 14, including means for changing a polarization characteristic of the light.

17. The display system of claim 16, wherein said means for changing includes a liquid crystal device.

18. The display system of claim 17, wherein said liquid crystal device is a surface mode liquid crystal device.

19. The display system of claim 17, wherein said liquid crystal device is a twisted nematic liquid crystal device.

20. The display system of claim 14, wherein the direction of light emitted from said means for shifting is parallel to the direction of light received by said means for shifting.

21. An optical display system, comprising:

a light source for producing a light signal at a first location;

means for alternatively shifting and not shifting the apparent source of the light signal from said first location to a second location, whereby the shifted and unshifted light signals are integrated by the eye of a viewer to form a composite image,

wherein the light source produces a light signal representing a plurality of spaced pixels, and

wherein said second location occupies at least a portion of the space between adjacent pixels.

22. The display system of claim 21, wherein said light source includes an active matrix liquid crystal display device.

23. The display system of claim 21, wherein the shifted and unshifted light signals contain the same information.

24. The display system of claim 21, wherein the shifted and unshifted light signals contain different information.

25. The display system of claim 21, wherein the direction of light signals emitted from said means for shifting is parallel to the direction of light signals received by said means for shifting.

26. The display system of claim 21, including means for changing a polarization characteristic of a light signal, wherein said means for shifting shifts a light signal based on a polarization characteristic of the light signal.

27. The display system of claim 26, wherein said means for changing includes a liquid crystal device.

28. The display system of claim 27, wherein said liquid crystal device is a surface mode liquid crystal device.

29. The display system of claim 27, wherein said liquid crystal device is a twisted nematic liquid crystal device.

30. The display system of claim 26, including means for operating said means for changing periodically for cooperation with said means for shifting to effect interlacing of the shifted and unshifted light signals.

31. An optical display system, comprising:

a light source for producing a light signal at a first location;

means for alternatively shifting and not shifting the apparent source of the light signal from said first location to a second location, whereby the shifted and unshifted light signals are integrated by the eye of a viewer to form a composite image,

wherein the light source produces a light signal representing a raster line, and

wherein said second location occupies at least a portion of the space between adjacent raster lines.

32. The display system of claim 31, wherein said light source is a cathode ray tube.

33. An optical display system, comprising:

a display for displaying optical information in the form of plural spaced pixels;

means for selectively shifting in a first direction light emitted from said display based on a polarization characteristic of the light, the shifted light being shifted a distance less than or equal to the space between adjacent said spaced pixels; and

means for selectively shifting in a second direction light emitted from said display based on a polarization characteristic of the light, the shifted light being shifted a distance less than or equal to the space between adjacent said spaced pixels.

34. An optical display system, comprising:

a cathode ray tube display for displaying optical information in the form of plural spaced raster lines; and

means for selectively shifting light emitted from said display based on a polarization characteristic of the light, the shifted light being shifted a distance less than or equal to the space between adjacent said spaced raster lines.