Dump path light intensity sensing in light projector

• US 8,142,021 B2
• Filed: 06/25/2009
• Issued: 03/27/2012
• 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.
• Primary Examiner(s): Epps, Georgia Y
• Assistant Examiner(s): Cruz, Magda
• Application Number:
  US12/491,288
• Publication Number:
  US 20100328610A1
• Time in Patent Office: 1,006 Days
• Field of Search: 353/7, 353/10, 353/94, 348/42, 348/51
• US Class Current: 353/7
• CPC Class Codes: G03B 21/2013 Plural light sources
• CPC Class Codes: G03B 21/2033 LED or laser light sources
• CPC Class Codes: G03B 21/2053 Intensity control of illuminating light controlled by video signal processing H04N5/74 or H04N9/31
• CPC Class Codes: G03B 33/12 using beam-splitting or beam-combining systems, e.g. dichroic mirrors
• CPC Class Codes: G03B 35/26 using polarised or coloured light separating different viewpoint images
• CPC Class Codes: H04N 13/324 Colour aspects
• CPC Class Codes: H04N 13/363 using image projection screens volumetric display H04N13/388
• CPC Class Codes: H04N 13/398 Synchronisation thereof; Control thereof
• 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 9/3161 using laser light sources using laser beams scanning the display screen H04N9/3129

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:

a projection subsystem configured at least to project an image;

an image forming subsystem comprising;

a plurality of light source subsystems, each configured at least to generate a single color channel of a plurality of color channels of light, and

a plurality of light modulation subsystems, each associated with a light source subsystem and configured at least to cause the light it receives from its associated light source subsystem to follow either a light dump path or an image path in a manner consistent with image data, the light dump path not leading to the projection subsystem, and the image path leading to the projection subsystem; and

a light-intensity-measurement subsystem configured at least to determine an intensity of each of the plurality of color channels of light and comprising at least one light-intensity sensor in at least one light dump path.

2. The system of claim 1, wherein a light-dump path exists for each of the plurality of color channels of light, and wherein the light-intensity-measurement subsystem comprises a light-intensity sensor in each light-dump path.

3. The system of claim 1, wherein the light is stereoscopic light comprising a left-eye light beam and a right-eye light beam that follow a same path along the light-dump path when so directed by the light modulation subsystem.

4. The system of claim 3, wherein the light-intensity sensor is configured at least to measure light intensity during a blanking period between the left-eye and right-eye light beams.

5. A method for measuring light intensity generated by a light projection system, the method comprising:

generating light from a light source subsystem;

directing the light, by a light modulation subsystem, along either an image path or a light dump path in a manner consistent with image data, the image path leading to a projection subsystem configured at least to project an image, and the light dump path not leading to the projection subsystem; and

determining an intensity of the light with in image sensor in the light dump path, wherein the light is stereoscopic light comprising a left-eye light beam and a right-eye light beam that follow a same path along the light-dump path when so directed by the light modulation subsystem.

6. The method of claim 5,

wherein the generating step generates a plurality of color channels of light, each from one of a plurality of light source subsystems,

wherein the directing step directs each of the color channels of light with a light modulation subsystem along either the image path or a light dump path not leading to the projection subsystem, and

wherein the determining step, determines an intensity of each of the plurality of color channels of light.

7. The method of claim 6, wherein the determining step occurs when only one of the plurality of light source subsystems are generating light.

8. The method of claim 6, wherein a light-dump path exists for each of the plurality of color channels of light, and wherein the determining step is performed with a light-intensity sensor in each light-dump path.

9. The method of claim 5, wherein the determining step determines light intensity during a blanking period between the left-eye and right-eye light beams.

10. The method of claim 5, wherein the determining step occurs during or contemporaneously with completion of construction of the light projection system.

11. The method of claim 5, wherein the determining step occurs during or contemporaneously with a startup procedure initiated by a powering-on or rebooting of the light projection system.

12. The method of claim 5, wherein the determining step occurs just prior to projecting a video with the light projection system.