Color filters and sequencers using color-selective light modulators

• US 20050122454A1
• Filed: 10/22/2004
• Published: 06/09/2005
• Est. Priority Date: 05/23/1995
• Status: Active Grant

• Current Assignee: RealD Incorporated
• Original Assignee: ColorLink, Incorporated (RealD Incorporated)
• Inventors: Sharp, Gary D.
• Granted Patent: US 7,511,787 B2
• Time in Patent Office: Days
• US Class Current: 349/119
• CPC Class Codes: G02B 27/288 Filters employing polarising elements, e.g. Lyot or Solc filters G02B5/3016 takes precedence
• CPC Class Codes: G02F 1/0136 for the control of polarisation, e.g. state of polarisation [SOP] control, polarisation scrambling, TE-TM mode conversion or separation G02F1/0353 takes precedence
• CPC Class Codes: G02F 1/0322 Arrangements comprising two or more independently controlled crystals
• CPC Class Codes: G02F 1/09 based on magneto-optical elements, e.g. exhibiting Faraday effect
• CPC Class Codes: G02F 1/133533 Colour selective polarisers G02F1/1347 takes precedence
• CPC Class Codes: G02F 1/133536 Reflective polarizers G02F1/13362 takes precedence
• CPC Class Codes: G02F 1/133543 Cholesteric polarisers
• 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 1/13473 for wavelength filtering or for colour display without the use of colour mosaic filters
• CPC Class Codes: G02F 1/23 for the control of the colour G02F1/03 - G02F1/21 take precedence
• CPC Class Codes: G02F 2413/04 Number of plates greater than or equal to 4
• CPC Class Codes: G02F 2413/08 with a particular optical axis orientation
• 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 9/3111 for displaying the colours sequentially, e.g. by using sequentially activated light sources sequential projection in colour photography G03B33/08
• CPC Class Codes: H04N 9/3167 for polarizing the light beam polarizing optical systems per se G02B27/28

Abstract

The present invention provides a high brightness color selective light modulator (CSLM) formed by a polarization modulator positioned between two retarder stacks. The modulator changes the apparent orientation of one retarder stack relative to the other so that, in a first switching state of the modulator the two retarder stacks cooperate in filtering the spectrum of input light, and in a second switching state the two retarder stacks complement each other, yielding a neutral transmission spectrum. Two or more CSLM stages can be used in series, each stage providing independent control of a primary color. One preferred embodiment eliminates internal polarizers between CSLM stages, thereby providing an additive common-path full-color display with only two neutral polarizers. Hybrid filters can be made using the CSLMs of this invention, in combination with other active or passive filters. The CSLMs of this invention can be used in many applications, particularly in the areas of recording and displaying color images. They can be arranged in a multi pixel array by pixelating the active elements, and can be implemented as color filter arrays, using patterned passive retarders rather than active polarization modulators.

Claims

1. A light modulator having a stack-only mode and a stack-altered mode, comprising:

a first retarder stack for receiving at least partially polarized input light;

an electro-optic modulator for receiving light from the first retarder stack;

a second retarder stack positioned to receive light output from the electro-optic modulator; and

an output polarizer for receiving and analyzing light from the second retarder stack;

wherein the first retarder stack, the electro-optic modulator, the second retarder stack and the output polarizer are adapted and oriented so that, in the stack-only mode, light transmitted by the output polarizer corresponds to a neutral state.

2. The light modulator of claim 1, wherein, in the stack-only mode, light transmitted by the output polarizer corresponds to a black state.

3. The light modulator of claim 2, wherein, in the stack-altered mode, light transmitted by the output polarizer corresponds to a primary filtered state.

4. The light modulator of claim 3, wherein the transmission of the primary filtered state by the output polarizer is continuously tunable.

5. The light modulator of claim 3, wherein the primary filtered state is one of a red state, a green state and a blue state.

6. The light modulator of claim 2, wherein, in the stack-altered mode, light transmitted by the output polarizer corresponds to one of a red state, a green state and a blue state.

7. The light modulator of claim 1, wherein, in the stack-only mode, light transmitted by the output polarizer corresponds to a white state.

8. The light modulator of claim 7, wherein, in the stack-altered mode, light transmitted by the output polarizer corresponds to a primary filtered state.

9. The light modulator of claim 8, wherein the transmission of the primary filtered state by the output polarizer is continuously tunable.

10. The light modulator of claim 8, wherein the primary filtered state is one of a cyan state, a magenta state and a yellow state.

11. The light modulator of claim 7, wherein, in the stack-altered mode, light transmitted by the output polarizer corresponds to one of a cyan state, a magenta state and a yellow state.

12. The light modulator of claim 1, wherein at least one of the first retarder stack and the second retarder stack comprises retarders welded together by chemical bonding.

13. The light modulator of claim 12, wherein the welded retarders are polycarbonate sheets.

14. The light modulator of claim 13, wherein the welded retarders are welded together using methylene chloride.

15. The light modulator of claim 14, wherein a dope is formed of polycarbonate dissolved in methylene chloride.

16. A reflection-mode light modulator for receiving input light and outputting modulated light, comprising:

an input polarizer;

a reflector;

an electro-optic modulator positioned between the input polarizer and the reflector; and

a retarder stack positioned between the input polarizer and the electro-optic modulator, said retarder stack comprising at least two retarders;

wherein the input polarizer, the retarder stack, the electra-optic modulator and the reflector are oriented and positioned in a reflection-mode arrangement.

17. The reflection-mode light modulator of claim 16, wherein the reflection-mode arrangement is a retro-reflecting arrangement.

18. The reflection-mode light modulator of claim 16, wherein the polarizations of the input light and the output modulated light are substantially parallel.

19. The reflection-mode light modulator of claim 16, wherein the retarder stack comprises at least three retarders.

20. The reflection-mode light modulator of claim 19, wherein the at least three retarders comprise polycarbonate retarders.

21. The reflection-mode light modulator of claim 16, wherein the retardances of the at least two retarders stack are such that the modulated output light is a primary color.

22. The reflection-mode light modulator of claim 16, wherein the retarder stack comprises retarders welded together by chemical bonding.

23. The reflection-mode light modulator of claim 22, wherein the welded retarders are polycarbonate sheets.

24. The reflection-mode light modulator of claim 23, wherein the welded retarders are welded together using methylene chloride.

25. The reflection-mode light modulator of claim 24, wherein a dope is formed of polycarbonate dissolved in methylene chloride.

26. A reflection-mode light modulator, comprising:

a polarizer;

a reflector;

a first electro-optic modulator positioned between the input polarizer and the reflector;

a second electro-optic modulator positioned between the first electro-optic modulator and the reflector;

a third electro-optic modulator positioned between the second electro-optic modulator and the reflector;

a first retarder stack positioned between the input polarizer and the first electro-optic modulator;

a second retarder stack positioned between the first and second electro-optic modulators; and

a third retarder stack positioned between the second and third electro-optic modulators;

wherein the polarizer, the first, second and third retarder stacks, the first, second and third electro-optic modulators, and the reflector are oriented and positioned in a reflection-mode arrangement.

27. The reflection-mode light modulator of claim 26, wherein the retardances and orientations of the first, second and third stacks are such that they each function substantially independent of each other.

28. The reflection-made light modulator of claim 26, wherein the first, second and third electro-optic modulators each have a higher chromaticity in a stack-altered mode than in a stack-only mode.

29. The reflection-mode light modulator of claim 26, wherein one of the first retarder stack, the second retarder stack, and the third retarder stack comprises retarders welded together by chemical bonding.

30. The reflection-mode light modulator of claim 29, wherein the welded retarders are polycarbonate sheets.

31. The reflection-mode light modulator of claim 30, wherein the welded retarders are welded together using methylene chloride.

32. The reflection-mode light modulator of claim 31, wherein a dope is formed of polycarbonate dissolved in methylene chloride.

33. A color selective light modulator for a projector, comprising:

a first polarizer;

a second polarizer; and

a first modulator stage positioned between the first and second polarizers, said first modulator stage exhibiting a red state in a stack-altered mode, and a black state in a stack-only mode;

a second modulator stage positioned between the first and second polarizers, said second modulator stage exhibiting a green state in a stack-altered mode, and a black state in a stack-only mode; and

a third modulator stage positioned between the first and second polarizers, said third modulator stage exhibiting a blue state in a stack-altered mode, and a black state in a stack-only mode.

34. The color selective light modulator of claim 33, wherein the orientations and retardances of the first, second and third modulator stages are such that they each operate substantially independent of each other.

35. The color selective light modulator of claim 33, wherein one of the first modulator stage, the second modulator stage, and the third modulator stage comprises a retarder stack, the retarder stack comprising retarders welded together by chemical bonding.

36. The color selective light modulator of claim 35, wherein the welded retarders are polycarbonate sheets.

37. The color selective light modulator of claim 36, wherein the welded retarders are welded together using methylene chloride.

38. The color selective light modulator of claim 37, wherein a dope is formed of polycarbonate dissolved in methylene chloride.