Hierarchical light intensity control in light projector

• US 8,162,483 B2
• Filed: 06/25/2009
• Issued: 04/24/2012
• Est. Priority Date: 06/25/2009
• Status: Active Grant

• Current Assignee: IMAX Theatres International Limited (IMAX Corporation)
• Original Assignee: Eastman Kodak Company
• Inventors: Silverstein, Barry D., Corey, Richard P., Dowe, David R.
• Primary Examiner(s): Dowling, William C
• Application Number:
  US12/491,275
• Publication Number:
  US 20100328616A1
• Time in Patent Office: 1,034 Days
• Field of Search: 353/31, 353/85, 353/88, 353/94, 348/742, 348/743, 348/771, 349/5, 349/7, 349/8, 349/9, 362/230, 362/231, 345/82, 345/83, 345/87
• US Class Current: 353/31
• CPC Class Codes: H04N 9/3129 scanning a light beam on the display screen scanning a light beam on a screen in displays other than projection devices G09G3/02; scanning systems in general G02B26/10; projectors using laser light sources in general H04N9/3161
• CPC Class Codes: H04N 9/3155 for controlling the light source light source control per se H05B35/00 – H05B47/00; control of an illumination source for displays in general G09G3/3406
• CPC Class Codes: H04N 9/73 Colour balance circuits, e.g. white balance circuits or colour temperature control camera processing pipelines for colour balance H04N23/88

Abstract

In a light projection system, potentially hierarchical levels of light intensity control ensure proper laser-light output intensity, color channel intensity, white point, left/right image intensity balancing, or combinations thereof. The light projection system can include a light intensity sensor in an image path, in a light-source subsystem light-dump path, in a light-modulation subsystem light-dump path, in a position to measure light leaked from optical components, or combinations thereof.

Claims

1. A light projection system comprising:

an image forming subsystem configured at least to output a plurality of different color channels of light, the image forming subsystem comprising a plurality of light source subsystems each configured at least to generate a single color channel of the plurality of color channels output by the image forming subsystem, each light source subsystem comprising a plurality of lasers; and

a light-intensity-correction subsystem configured at least to;

determine laser light intensities output by individual lasers in each light source subsystem,

control each light source subsystem to change a light intensity of an individual laser if an absolute value of the corresponding determined laser light intensity deviates from a predetermined laser light intensity by a first threshold amount;

determine a color channel intensity for each of the plurality of color channels;

control each light source subsystem to change a light intensity output therefrom if an absolute value of the corresponding determined color channel intensity deviates from a predetermined color channel intensity by a second threshold amount;

determine a white point of the plurality of color channels; and

control the light source subsystems to change an intensity of one or more of the plurality of color channels if an absolute value of the determined white point deviates from a predetermined white point by a third threshold amount.

2. The system of claim 1, wherein the plurality of lasers in each light source subsystem output less than a maximum laser light intensity.

3. The system of claim 1, further comprising:

a projection subsystem configured at least to project an image,

wherein the image forming subsystem further comprises;

a plurality of light modulation subsystems each configured at least to interact with one of the plurality of different color channels in a manner consistent with image data

wherein the light modulation subsystems each cause its color channel to follow either a light dump path or an image path in a manner consistent with the image data, and

wherein the light dump path(s) do not lead to the projection subsystem and the image path(s) do lead to the projection subsystem.

4. The system of claim 3, wherein each of the multiple color channels have separate light dump paths, and wherein the light-intensity-correction subsystem includes a light-intensity sensor in each light dump path.

5. The system of claim 4, wherein the light-intensity-correction subsystem determines the white point, the color channel intensities, or both based at least on input received from the light-intensity sensors in each light dump path.

6. The system of claim 3, wherein each of the multiple color channels share a light dump path, and wherein the light-intensity-correction subsystem includes a light-intensity sensor in the shared light dump path.

7. The system of claim 6, wherein the light-intensity-correction subsystem determines the white point, the color channel intensities, or both based at least on input received from the light-intensity sensor in the shared light dump path.

8. The system of claim 3, wherein the light-intensity-correction subsystem includes a light-intensity sensor in at least on one image path.

9. The system of claim 8, wherein the sensor is on a shutter in a closed position that prevents further projection of light in its path.

10. The system of claim 8, wherein the sensor is in a location in an image path where all of the plurality of color channels have been combined.

11. The system of claim 8, wherein the sensor is in a location in an image path where the plurality of color channels have not been combined.

12. The light projection system of claim 1, wherein if the light-intensity-correction subsystem determines first that a color channel intensity from a first of the light source subsystems is lower than a predetermined color channel intensity by at least a threshold amount, and determines second that the color channel intensity from the first light source subsystem cannot be increased to within the threshold amount of the predetermined color channel intensity then in response a color channel intensity for a second of the light source subsystem is reduced.

13. The system of claim 12, wherein the first determining occurs as part of the white point determination step.

14. A method for correcting light intensity generated by an image forming system, the method comprising:

generating, from the image forming system, a plurality of different color channels of light, the image forming system comprising a plurality of light source subsystems each configured at least to generate a single color channel of the plurality of color channels generated by the image forming system, each light source subsystem comprising a plurality of lasers;

determining laser light intensities output by individual lasers in each light source subsystem,

controlling each light source subsystem to change a light intensity of an individual laser if an absolute value of the corresponding determined laser light intensity deviates from a predetermined laser light intensity by a first threshold amount;

determining a color channel intensity for each of the plurality of color channels;

controlling each light source subsystem to change a light intensity output therefrom if an absolute value of the corresponding determined color channel intensity deviates from a predetermined color channel intensity by a second threshold amount;

determining a white point of the plurality of color channels; and

controlling the light source subsystems to change an intensity of one or more of the plurality of color channels if an absolute value of the determined white point deviates from a predetermined white point by a third threshold amount.

15. The method of claim 14, wherein at least some of the determining and changing occurs during or contemporaneously with completion of construction of the image forming system.

16. The method of claim 14, wherein at least some of the determining and changing occurs during or contemporaneously with a startup procedure initiated by a powering-on or rebooting of the image forming system.

17. The method of claim 14, wherein at least some of the determining and changing occurs just prior to projecting a video with the image forming system.

18. The method of claim 14, wherein at least some of the determining occurs when only one of the plurality of light source subsystems are generating light.

19. The method of claim 14, wherein at least some of the determining occurs by a light-intensity sensor on a shutter, and wherein the method further comprises closing the shutter into a closed position that prevents further projection of light in its path, the closing occurring prior to at least some of the determining.

20. The method of claim 19, wherein the determining of the laser light intensities occurs at a first frequency, the determining of the color channel intensities occurs at a second frequency lower than the first frequency, and the determining of the white point occurs at a third frequency lower than the second frequency.

21. The method of claim 20, wherein the first frequency is between approximately 50 kHz to approximately 200 kHz.

22. The method of claim 20, wherein the second frequency is between approximately 1 kHz to approximately 10 kHz.

23. The method of claim 21, wherein the second frequency is between approximately 1 kHz to approximately 10 kHz, and wherein the third frequency is about 1 or 2 cycles per second.

24. The method of claim 14, wherein if it is determined first that a color channel intensity from a first of the light source subsystems is lower than the predetermined color channel intensity by a threshold amount and it is determined second that the color channel intensity from the first light source subsystem cannot be increased to within the threshold amount of the predetermined color channel intensity, then in response a color channel intensity for a second light source subsystem is reduced.

25. The method of claim 24, wherein the first determining occurs as part of the white point determination process.