Method and apparatus for increasing microdisplay black state in light management systems and flexibility to utilize polarized or unpolarized input light

• US 7,280,281 B2
• Filed: 03/05/2003
• Issued: 10/09/2007
• Est. Priority Date: 03/05/2002
• Status: Expired due to Fees

• Current Assignee: Lightmaster Systems Incorporated
• Original Assignee: Berg & Berg Enterprises, LLC (Carl Edwin Berg)
• Inventors: Berman, Arthur
• Primary Examiner(s): Dang; Hung Xuan
• Assistant Examiner(s): TRA, TUYEN Q
• Application Number:
  US10/382,766
• Publication Number:
  US 20040008418A1
• Time in Patent Office: 1,679 Days
• Field of Search: 359/242, 359/259, 359/267, 359/618, 359/629, 359/634, 359/636, 359/638, 359/640, 359/627, 348/751, 348/752, 348/757, 345/38, 345/40, 345/42, 345/87, 349/5, 349/8, 349/9, 349/62, 349/76, 353/33, 353/39, 353/81, 324/770
• US Class Current: 359/627
• CPC Class Codes: G02B 27/1013 for colour or multispectral image sensors, e.g. splitting an image into monochromatic image components on respective sensors spectral imaging systems G01J
• CPC Class Codes: G02B 27/1026 for use with reflective spatial light modulators
• CPC Class Codes: G02B 27/145 having sequential partially reflecting surfaces
• CPC Class Codes: G02B 27/283 used for beam splitting or combining
• CPC Class Codes: G02F 1/1362 Active matrix addressed cells G02F1/134336, G02F1/134363 take precedence
• CPC Class Codes: G02F 2203/02 reflective
• CPC Class Codes: G09G 2320/0693 Calibration of display systems
• CPC Class Codes: G09G 3/002 to project the image of a two-dimensional display, such as an array of light emitting or modulating elements or a CRT
• CPC Class Codes: H04N 9/3105 for displaying all colours simultaneously, e.g. by using two or more electronic spatial light modulators simultaneous projection in colour photography G03B33/10; beam splitting or combining systems per se G02B27/10
• CPC Class Codes: H04N 9/3167 for polarizing the light beam polarizing optical systems per se G02B27/28
• CPC Class Codes: H04N 9/3191 Testing thereof testing of displays in general G09G3/006

Abstract

A dichroic is positioned to separate color beams of polarized input light. The color beams are directed to microdisplays that contain correspondingly colored content in a kernel of a Light Management System (LMS). Adjustment of a voltage amplitude of the microdisplays is set to produce a maximum black state of the LMS. In one embodiment, a passive nematic liquid crystal device is utilized as a quarter waveplate. A thickness of a liquid crystal layer (d) is matched to a birefringence (Δn) of the nematic such that retardation dΔn =¼λ.

Claims

1. A quality control method comprising the steps of:

producing a display device having at least one microdisplay; and

setting a voltage amplitude on said at least one microdisplay to produce a highest black state of the display device, wherein;

said at least one microdisplay comprises a set of microdisplay devices;

said step of producing comprises producing a display device having a set of channels each comprising a light path for a specific band of light interacting with one of the microdisplay devices, each microdisplay device having a waveplate that compensates for residual retardation of the microdisplay; and

said waveplate comprises a passive nematic cell.

2. The method according to claim 1, wherein the set of microdisplay devices comprise a set of Liquid Crystal On Silicon (LCOS) microdisplay devices.

3. The method according to claim 1, wherein the display device comprises a Liquid Crystal On Silicon (LCOS) video projection device.

4. A quality control method comprising the steps of:

producing a display device having at least one microdisplay; and

setting a voltage amplitude on said at least one microdisplay to produce a highest black state of the display device wherein;

said display device comprises a kernel, comprising,

an input face configured to receive input polarized light, and

a beam separating dichroic arranged on a diagonal to the input polarized light and configured to separate the input polarized light into a first color beam and a second color beam.

5. The method according to claim 4, wherein said at least one microdisplay comprises a Liquid Crystal On Silicon (LCOS) microdisplay device.

6. The method according to claim 4, wherein said display device comprises a Liquid Crystal On Silicon (LCOS) video projection device.

7. A method of increasing the darkness of a black state of a microdisplay, comprising the steps of:

applying a voltage to the microdisplay to invoke a black state;

observing the black state;

adjusting the voltage until the black state reaches its darkest point;

setting a black state voltage to the applied voltage when the microdisplay reaches its darkest point.

8. The method according to claim 7, wherein the microdisplay comprises one of a red, green, and blue microdisplay in a kernel.

9. The method according to claim 8, wherein the steps of applying, observing, adjusting, and setting are applied to each of the red, green, and blue microdisplays in the kernel to determine a max black state of the kernel.

10. The method according to claim 7, wherein the method is applied to each microdisplay in a kernel to determine a max black state comprising a set of black state voltages, each black state voltage corresponding to a darkest point in one of the microdisplays.

11. The method according to claim 7, wherein the step of applying comprises applying a Vdd voltage to the microdisplay.

12. The method according to claim 7, wherein the black state voltage comprises a voltage less than a Vdd voltage of the microdisplay.

13. The method according to claim 7, wherein the microdisplay comprises a Liquid Crystal On Silicon (LCOS) microdisplay device.

14. The method according to claim 7, wherein the method is performed on microdisplays in a Liquid Crystal On Silicon (LCOS) video projection device.

15. The method according to claim 7, wherein the method is performed on microdisplays mounted on a prism assembly.

16. The method according to claim 7, wherein the microdisplays comprise Liquid Crystal On Silicon (LCOS) microdisplays.

17. A kernel, comprising:

a set of microdisplays;

a set of optics configured to divide input light into a set of primary colors and direct each primary color to one of the microdisplays for modulation; and

a control module configured to set an amount of modulation imposed on each primary color by its corresponding microdisplay;

wherein the control module includes a set of black state voltages, each black state voltage corresponding to a darkest point in one of the microdisplays, and each black state voltage is not a Vdd of its corresponding microdisplay.

18. The kernel according to claim 17, wherein each black state voltage is less than a Vdd of its corresponding microdisplay.

19. The kernel according to claim 17 wherein the set of black state voltages are obtained by adjusting a voltage applied to the microdisplay while observing an output screen displaying an output of the kernel.

20. The kernel according to claim 17, wherein the black state voltage is determined for each microdisplay by,

applying a maximum voltage to the microdisplay to invoke a black state;

observing the black state;

lowering the voltage until the black state reaches its darkest point; and

setting the black state voltage to the voltage when the microdisplay reaches its darkest point.

21. The kernel according to claim 17, further comprising a set of passive nematic based quarter waveplates each disposed between one of the microdisplay and the set of optics.

22. The kernel according to claim 17, further comprising a set of quarter waveplates cut such that the principle axes of each quarter waveplate are at an angle to sides of the quarter waveplates;

wherein each quarter waveplate is disposed in a color light channel of the kernel.

23. The kernel according to claim 22, wherein the quarter waveplate is centered on a color wavelength of the color light channel in which it is disposed.

24. The kernel according to claim 17, wherein the microdisplays comprise Liquid Crystal On Silicon (LCOS) microdisplays.

25. The kernel according to claim 17, wherein the kernel is part of a Liquid Crystal On Silicon (LCOS) video projection device.