Apparatus and method for calibration of DLP/DMD projection image systems

• US 7,639,901 B2
• Filed: 05/24/2006
• Issued: 12/29/2009
• Est. Priority Date: 05/24/2005
• Status: Active Grant

• Current Assignee: X-Rite Switzerland GmbH (Danaher Corporation)
• Original Assignee: X-Rite Europe GmbH (Veralto Corp.)
• Inventors: Lianza, Thomas A.
• Primary Examiner(s): HEALY, BRIAN
• Application Number:
  US11/440,336
• Publication Number:
  US 20060268387A1
• Time in Patent Office: 1,315 Days
• Field of Search: 385/115, 385/116, 385/88, 385/89, 385/901, 385/12, 353/88, 353/89, 353/84, 353/69, 345/587, 345/207, 345/690, 250/227.11, 359/290, 359/291, 359/292
• US Class Current: 385/12
• CPC Class Codes: G01J 3/02 Details
• CPC Class Codes: G01J 3/0218 using optical fibers
• CPC Class Codes: G01J 3/0256 Compact construction
• CPC Class Codes: G02B 26/0833 the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD G02B26/0825 takes precedence; micromechanical devices in general B81B
• CPC Class Codes: G02B 6/0008 the light being emitted at the end of the fibre
• CPC Class Codes: G02B 6/001 the light being emitted along at least a portion of the lateral surface of the fibre
• CPC Class Codes: G02B 6/0076 Stacked arrangements of multiple light guides of the same or different cross-sectional area
• CPC Class Codes: G02B 6/06 the relative position of the fibres being the same at both ends, e.g. for transporting images
• CPC Class Codes: G02B 6/2852 using tapping light guides arranged sidewardly, e.g. in a non-parallel relationship with respect to the bus light guides (light extraction or launching through cladding, with or without surface discontinuities, bent structures)
• CPC Class Codes: H04N 9/3182 Colour adjustment, e.g. white balance, shading or gamut white balance per se H04N9/73; control of amplitude of colour signals H04N9/68; colour control circuits for displays in general G09G5/02, G09G3/2003, G09G3/3607
• CPC Class Codes: H04N 9/3194 including sensor feedback
• CPC Class Codes: Y10S 385/901 Illuminating or display apparatus

Abstract

Display systems that utilize digital micro-mirror device (DMD) technology are finding wide application in the areas of projection systems for color display. The common name for such systems is digital light processing projection systems or DLP projection systems. The systems and methods described herein utilize the non-imaging light to monitor and calibrate the projected image since the high levels of illumination and extreme temperatures of the imaging light require careful attention to the manner of light collection. Light collection is accomplished in a waste gate area by a light collector, e.g., an optical fiber mat, and the collected light is communicated to an associated sensor. The technique is non-invasive and may be applied to existing designs with minimal modification.

Claims

1. A device, comprising:

a light collector disposed at a waste gate area of a digital light processing projection system; and

an optical sensor in operable communication with said light collector, wherein said sensor receives wasted reflected light from said waste gate area, said wasted reflected light substantially correlated to a light signal striking an image display.

2. A device according to claim 1, wherein the light collector includes an optical fiber mat.

3. A device according to claim 2, wherein the waste gate area defines a geometry and wherein the optical fiber mat is configured and dimensioned to substantially correspond to the waste gate area geometry.

4. A device according to claim 2, wherein the optical fiber mat is woven from plastic optical fibers and fill thread.

5. A device according to claim 2, wherein the optical fiber mat is multi-layered and includes a reflector layer and a clear top layer to provide increased durability.

6. A device according to claim 1, further comprising a light-transmitting fiber for transmitting light from the light collector to the optical sensor.

7. A device according to claim 1, wherein measurement of the wasted reflected light is used to generate a calibration map for calibration of a digital micro-mirror device (DMD).

8. A system for providing calibration in a DLP system comprising:

an external sensor sensing at least one of intensity and spectral character of a light signal striking image on a display;

a light collector disposed at a waste gate area of a digital light processing projection system; and

an optical sensor in operable communication with said light collector, wherein said sensor receives wasted reflected light from said waste gate area, said wasted reflected light substantially correlated to the light signal striking said display.

9. A system according to claim 8, wherein the light collector includes an optical fiber mat.

10. A system according to claim 9, wherein the waste gate area defines a geometry and wherein the optical fiber mat is configured and dimensioned to substantially correspond to the waste gate area geometry.

11. A system according to claim 8, wherein measurement of the wasted reflected light is used to generate a calibration map for calibration of a digital micro-mirror device (DMD).

12. A system according to claim 11, wherein the calibration map is applied to drive constants associated with the digital micro-mirror device (DMD).

13. A system according to claim 11, wherein the calibration map is applied through an interface to a data stream associated with the digital micro-mirror device (DMD).

14. A method of calibrating a projection system, the method comprising:

disposing a light collector at a waste gate area in the projection system; and

receiving wasted reflected light at an optical sensor having R, G, B and unfiltered sensors, wherein an output of each R, G, B and unfiltered sensor is a time varying waveform having a frequency linearly proportional to wasted reflected light striking said each R, G, B and unfiltered sensor.

15. A method according to claim 14, further comprising:

measuring a first set of data corresponding to a set of color patches from a display with an external reference device;

collecting a second set of data corresponding to RGB exposure data from an internal optical sensor and collecting a bias simultaneously with said measuring;

entering said first and second sets of data into a corresponding matrix; and

computing a resulting 3×

3 matrix using a least squares method.

16. A method according to claim 14, further comprising generating a calibration map based on the time varying waveform.

17. A method according to claim 16, further comprising applying the calibration map to drive constants associated with a digital micro-mirror device (DMD).

18. A method according to claim 16, further comprising applying the calibration map to a data stream associated with a digital micro-mirror device (DMD).

19. A method according to claim 14, wherein the light collector includes an optical fiber mat.

20. A method according to claim 14, wherein the optical sensor is spaced from the light collector a distance sufficient to avoid heat damage to the optical sensor based on heat generated in the waste gate area.