Apparatus and method for calibration of DLP/DMD projection image systems
View Patent ↗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.
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.