Color filters, sequencers and displays using color selective light modulators

• US 6,417,892 B1
• Filed: 07/30/1999
• Issued: 07/09/2002
• Est. Priority Date: 05/23/1995
• Status: Expired due to Term

• Current Assignee: RealD Incorporated
• Original Assignee: ColorLink, Incorporated (RealD Incorporated)
• Inventors: Sharp, Gary D., Johnson, Kristina M.
• Primary Examiner(s): Lee, Michael
• Assistant Examiner(s): Lo, Linus H.
• Application Number:
  US09/362,497
• Time in Patent Office: 1,075 Days
• Field of Search: H04/N.912, 348/742, 348/750, 348/752, 348/758, 348/759, 348/762, 348/767, 349/18, 349/119, 349/117, 349/97, 349/120, 349/106, 349/121
• US Class Current: 348/742
• 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 9/3126 for spatial light modulators in series
• 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 sequencer, comprising:

a first modulator stage, comprising;

a first input retarder stack for receiving and transforming the polarization of light,

a first electro-optic modulator for receiving and selectively modulating the polarization of a portion of light output by the first retarder stack, and

a first output retarder stack for receiving and transforming the polarization of light output by the first electro-optic modulator;

a second modulator stage, comprising;

a second input retarder stack for receiving and transforming the polarization of light,

a second electro-optic modulator for receiving and selectively modulating the polarization of a portion of light output by the second retarder stack, and

a second output retarder stack for receiving and transforming the polarization of light output by the second electro-optic modulator; and

a third modulator stage, comprising;

a third input retarder stack for receiving and transforming the polarization of light,

a third electro-optic modulator for receiving and selectively modulating the polarization of a portion of light output by the third retarder stack, and

a third output retarder stack for receiving and transforming the polarization of light output by the third electro-optic modulator;

wherein the first, second and third modulator stages each comprise at least one compensator having retardances and orientations that increase a field-of-view of the sequencer.

2. The sequencer of claim 1, wherein the at least one compensator in the first and second modulator stages each comprises an in-plane compensator and a z-compensator.

3. The sequencer of claim 1, wherein the at least one compensator in the third modulator stage comprises an in-plane compensator.

4. A sequencer, comprising:

a first modulator stage, comprising;

a first input retarder stack for receiving and transforming the polarization of at least partially polarized light,

a first electro-optic modulator for receiving and selectively modulating the polarization of a portion of light output by the first retarder stack, and

a first output retarder stack for receiving and transforming the polarization of light output by the first electro-optic modulator, wherein the first output retarder stack comprises a first in-plane compensator and a first z-plane compensator having respective retardances and orientations;

a second modulator stage, comprising;

a second input retarder stack for receiving and transforming the polarization of light,

a second electro-optic modulator for receiving and selectively modulating the polarization of a portion of light output by the second retarder stack, and

a second output retarder stack for receiving and transforming the polarization of light output by the second electro-optic modulator, wherein the second output retarder stack comprises a second in-plane compensator and a second z-plane compensator having respective retardances and orientations; and

a third modulator stage, comprising;

a third input retarder stack for receiving and transforming the polarization of light,

a third electro-optic modulator for receiving and selectively modulating the polarization of a portion of light output by the third retarder stack, and

a third output retarder stack for receiving and transforming the polarization of light output by the third electro-optic modulator, wherein the third output retarder stack comprises a third in-plane compensator having a retardance and orientation;

wherein the retardances and orientations of the first, second and third in-plane compensators, and the retardances and orientations of the first and second z-compensators are adapted to increase a field-of-view of the sequencer.

5. The sequencer of claim 4, wherein the first and second z-compensators each comprise cellulose triacetate or a biaxially stretched polymer.

6. The sequencer of claim 4, wherein the first, second and third modulator stages function substantially independent of each other.

7. The sequencer of claim 4, wherein the first, second and third modulator stages each exhibit a filtered state and a neutral state when their respective electro-optic modulators are in the stack-altered mode and the stack-only mode, respectively.

8. The sequencer of claim 7, wherein the neutral state is a black state.

9. The sequencer of claim 7, wherein the neutral state is a white state.

10. The sequencer of claim 6, wherein a state of each of the first, second and third modulator stages is switchable between one additive primary filtered state and a neutral state.

11. The sequencer of claim 10, wherein the state of the first, second and third modulator stages is switchable between red and black states, green and black states, and blue and black states, respectively.

12. The sequencer of claim 4, wherein a state of each of the first, second and third modulator stages is switchable between one subtractive primary filtered state and a neutral state.

13. The sequencer of claim 12, wherein the state of the first, second and third modulator stages is switchable between cyan and white states, magenta and white states, and yellow and white states, respectively.

14. The sequencer of claim 4, wherein a peak transmission of one of the first, second and third modulator stages is tunable so that its peak transmission coincides with a peak transmission of a respective filtered state.

15. The sequencer of claim 4, further comprising:

an input polarizer for receiving input light and outputting the at least partially polarized light; and

an output polarizer for receiving and analyzing light output by the third output retarder stack.