Color controllable illumination device, indicator lights, transmissive windows and color filters employing retarder stacks

• US 6,252,638 B1
• Filed: 11/13/1998
• Issued: 06/26/2001
• 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): Parker, Kenneth
• Application Number:
  US09/190,273
• Time in Patent Office: 956 Days
• Field of Search: 349/1, 349/5, 349/6, 349/119, 349/18, 349/61, 362/293, 353/30, 353/84
• US Class Current: 349/5
• CPC Class Codes: G02F 1/13471 in which all the liquid crystal cells or layers remain transparent, e.g. FLC, ECB, DAP, HAN, TN, STN, SBE-LC cells G02F1/13475 takes precedence
• CPC Class Codes: G02F 1/139 based on orientation effects in which the liquid crystal remains transparent
• CPC Class Codes: G02F 2413/00 Indexing scheme related to G02F1/13363, i.e. to birefringent elements, e.g. for optical compensation, characterised by the number, position, orientation or value of the compensation plates

Abstract

A color filter device for controlling the color of light output by an illumination device or for controlling the color of light passing through a window includes at least a retarder and a polarization analyzer. The device may also include an input polarizer. The device may further include an electrically controllable modulator and an output retarder for selectively controlling the spectrum of light output by the device. A color filter device embodying the invention enables rapid and effective control over the spectrum and amplitude of light passing through the filter to achieve desired effects. A device embodying the invention could be an indicator light, an illumination device, a diagnostic testing device, a transmissive window, or any other type of device where rapid and effective control of a spectrum of light is desired.

Claims

1. An illumination device, comprising:

a light source; and

at least one non-moving electro-optic color filter stage configured to selectively vary a respective predetermined spectrum of light output by the illumination device in response to a color signal, wherein the al least one electro-optic color filter stage comprises,

an input retarder stack that transforms a polarization state of the respective predetermined spectrum of light into a modulation state of polarization, and

a modulator, optically coupled to the retarder stack, adapted to operate on light having the modulation state of polarization more than light having other states of polarization.

2. The illumination device of claim 1, wherein the at least one electro-optic color filter stage comprises at least two electro-optic color filter stages that selectively vary at least two respective spectra of light output by the illumination device.

3. The illumination device of claim 1, wherein the at least two color filter stages are arranged inseries, and wherein the at least two respective predetermined spectra are not co-extensive.

4. The illumination device of claim 1, wherein the electro-optic color filter stage further comprises a polarization analyzer.

5. The illumination device of claim 1, wherein the electro-optic color filter stage further comprises an output retarder stack.

6. The illumination device of claim 1, further comprising a housing configured for use in stage lighting applications.

7. The illumination device of claim 1, wherein the device is configured to provide a beam of light suitable for stage lighting.

8. The illumination device of claim 1, further comprising a housing, wherein the light source and the at least one electro-optic color filter stage comprise at least one indicator light in the housing.

9. The illumination device of claim 1, wherein the light source comprises at least one of the group consisting of an incandescent light, a fluorescent light, a halogen light, a metal halide light, a tungsten light, a gas filled discharge tube, a plasma light, a laser light, a vertical cavity surface emitting laser light, and a light emitting diode.

10. The illumination device of claim 1, further comprising a rotatable mount configured such that light output by the illumination device can be aimed in a plurality of directions.

11. The illumination device of claim 1, wherein the modulator comprises a pixelated modulator.

12. The illumination device of claim 11, wherein the modulator comprises at least one device selected from the group consisting of:

a STN, TN, VAN, HAN, FLC, or polysilicon TFT LCD, and a reflective modulator.

13. The illumination device of claim 1, wherein the device is configured to provide a beam of light suitable for indoor or outdoor lighting applications.

14. An illumination device, comprising:

a light source;

a retarder stack arranged to receive light from the light source, wherein the retarder stack comprises at least two retarder films each having s retardance and an orientation selectively matched to a spectral output of the light source, such that a desired spectral portion of the light source is transmitted through the retarder stack and polarized with a first polarization when light from the light source passes through the at least two retarder films; and

an output polarization analyzer arranged to receive light generated by the light source that has passed through the retarder stack, wherein the output polarization analyzer is adapted to pass, block or redirect light polarized with the first polarization, wherein the light source has a known optical spectrum and a region of peak optical power within the optical spectrum substantially matched to the desired spectral portion and the retarder stack is selected such that the optical power for the desired spectral portion of the light source polarized with a first polarization is maximized.

15. The illumination device of claim 14, further comprising an input polarizer arranged between the light source and the retarder stack.

16. The illumination device of claim 14, wherein the at least two retarder films comprise polymer retarders.

17. The illumination device of claim 14, wherein the at least two retarder films comprise polymer retarders.

18. The illumination device of claim 14, wherein the at least two retarder films comprise polymer films.

19. The illumination device of claim 14, wherein the at least two retarder films comprise retarder sheets.

20. The illumination device of claim 14, wherein the desired spectral portion comprises a desired color.

21. The illumination device of claim 14, wherein the desired color comprises a desired primary color.