Calibration system and method for light modulation device

• US 8,077,378 B1
• Filed: 11/12/2009
• Issued: 12/13/2011
• Est. Priority Date: 11/12/2008
• Status: Expired due to Fees

• Current Assignee: Evans & Sutherland Computer Corp. (Elevate Entertainment, Inc.)
• Original Assignee: Evans & Sutherland Computer Corp. (Elevate Entertainment, Inc.)
• Inventors: Elkins, Dennis F., Winkler, Bret D., Bass, Michael Wayne
• Primary Examiner(s): Pinkney, Dawayne
• Application Number:
  US12/617,649
• Time in Patent Office: 761 Days
• Field of Search: 359290-291, 359223-225, 359/245, 359260-263, 359/298, 359301-303, 359317-318, 359/237, 359/242, 359/295, 359230-231, 359/238, 359/240, 359/247, 359/267, 359/649
• US Class Current: 359/291
• CPC Class Codes: G09G 2320/0693 Calibration of display systems
• CPC Class Codes: G09G 2360/147 the originated light output being determined for each pixel
• CPC Class Codes: G09G 3/20 for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters

Abstract

A calibration method for a grating light modulator includes calibrating light reflective ribbons on the modulator on a pixel-by-pixel basis. The method further includes performing a dark-state calibration and a bright-state calibration for each pixel. Once completed, the results of the dark-state calibration and the bright-state calibration may be combined to ensure a smooth transition between a dark state and a bright state for each pixel.

Claims

1. A method of calibrating a plurality of pixels of a light modulation device, each of said pixels comprising a first elongated element and a second elongated element, comprising:

applying a voltage to the first elongated elements of each of the plurality of pixels such that they are deflected to a common biased position; and

determining a light intensity response for each of the plurality of pixels, pixel-by-pixel, using a photodetector while said first elongated elements are held at the common biased position using a processing device.

2. The method of claim 1, wherein said common biased position resides below the second elongated elements in an undeflected state.

3. The method of claim 1, wherein determining a light intensity response for each of the plurality of pixels, pixel-by-pixel, further comprises:

selecting one of the plurality of pixels for calibration;

toggling the second elongated element of the pixel selected for calibration;

capturing light reflected off of the plurality of pixels using the photodetector;

generating a signal using the photodetector based upon the captured light, the signal comprising a first portion corresponding to the pixel selected for calibration and a second portion corresponding to the pixels not selected for calibration;

filtering the signal to thereby remove the second portion of the signal; and

using the first portion of the signal to determine a light intensity response for the pixel selected for calibration.

4. The method of claim 3, further comprising toggling the second elongated element of the pixel selected for calibration at a predetermined frequency.

5. The method of claim 1, further comprising determining an input value for the second elongated element of each of the plurality of pixels at which the first elongated element and the second elongated element of that pixel are substantially planar.

6. The method of claim 1, further comprising toggling the second elongated element of each of the plurality of pixels between one of a plurality of discrete positions and a reference position, and measuring a light intensity output for the pixel at each of the plurality of discrete positions.

7. The method of claim 6, further comprising determining from the measured light intensity output, an input value for the second elongated element of each of the plurality of pixels at which the light intensity output is at a minimum.

8. The method of claim 6, further comprising using the measured light intensity output in a polynomial curve fit to thereby determine an input value for the second elongated element of each of the plurality of pixels at which the light intensity output is at a minimum.

9. The method of claim 1, further comprising determining a light intensity response for each of the plurality of pixels in a sequential order.

10. The method of claim 1, further comprising positioning the second elongated elements of a group of uncalibrated pixels to an estimated minimum intensity position while determining the light intensity response of a pixel.

11. The method of claim 1, further comprising toggling the second elongated element of a pixel at a predetermined frequency.

12. The method of claim 1, further comprising determining the light intensity response for each pixel using a lock-in amplifier.

13. The method of claim 1, wherein determining a light intensity response for each of the plurality of pixels, pixel-by-pixel, further comprises determining a first light intensity response for a first operating range of each pixel and a second light intensity response for a second operating range of each pixel.

14. The method of claim 13, further comprising generating a look-up table from the first light intensity response and the second light intensity response for each pixel.

15. The method of claim 13, wherein said second light intensity response is for a state brighter than said first light intensity response.

16. The method of claim 1, further comprising generating a look-up table for each of the plurality of pixels.

17. A system for calibrating a plurality of pixels of a light modulation device, each of said pixels comprising a first elongated element and a second elongated element, said system comprising:

at least one light source;

a photodetector for measuring a light intensity output of each of the plurality of pixels;

a control device for positioning said first elongated elements to a common biased position;

said control device further operable to toggle the second elongated elements of the plurality of pixels, one-by-one, while the first elongated elements are positioned at the common biased position; and

a processing device for determining a light intensity response for each the plurality of pixels on a pixel-by-pixel basis.

18. The system of claim 17, wherein said control device is further operable for positioning said photodetector in an optical output path of each of the plurality of pixels.

19. The system of claim 17, further comprising a lock-in amplifier for isolating a light intensity output of a single pixel on the light modulation device.

20. The system of claim 17, wherein said common biased position resides below the second elongated elements of the plurality of pixels in an undeflected state.

21. The system of claim 17, wherein said control device is further operable to toggle each of the second elongated elements at a predetermined frequency.

22. The system of claim 17, wherein said processing device is further operable to determine an input value for the second elongated element of each of the plurality of pixels at which the first elongated element and the second elongated element are substantially planar.

23. The system of claim 17, wherein said light intensity response for each pixel comprises a first light intensity response for a first operating range of the pixel and a second light intensity response for a second operating range of the pixel.

24. The system of claim 23, wherein said second light intensity response is for a state brighter than said first light intensity response.

25. The system of claim 17, wherein said processing device is further operable to generate a look-up table for each of the plurality of pixels.

26. A system for calibrating a plurality of pixels of a light modulation device, each of said pixels comprising a first elongated element and a second elongated element, said system comprising:

means for deflecting a first group of elongated elements to a common biased position; and

means for determining a light intensity response for the plurality of pixels on a pixel-by-pixel basis while said first elongated elements are held at the common biased position using a processing device.

27. The system of claim 26, further comprising means for toggling the second elongated elements at a predetermined frequency.

28. The system of claim 26, further comprising means for measuring a light intensity output of each of the plurality of pixels.

29. The system of claim 26, further comprising means for isolating a light intensity output of a single pixel on the light modulation device.

30. The system of claim 26, wherein said light intensity response for each of the plurality of pixels comprises a first light intensity response for a first operating range of the pixel and a second light intensity response for a second operating range of the pixel.

31. The system of claim 30, wherein said second light intensity response is for a state brighter than said first light intensity response.

32. The system of claim 26, further comprising means for generating a look-up table for each of the pixels.

33. The system of claim 26, further comprising means for generating incident light onto the light modulation device.

34. A non-transitory computer readable medium for storing computer instructions that, when executed on a computer, enable a processor-based system to:

deflect a first group of elongated elements on a light modulation device to a common biased position; and

determine a light intensity response for the plurality of pixels on a pixel-by-pixel basis while the first elongated elements are held at the common biased position.