Thermal compensation in image projection

• US 10,506,206 B2
• Filed: 05/06/2016
• Issued: 12/10/2019
• Est. Priority Date: 05/06/2015
• Status: Active Grant

• Current Assignee: Dolby Laboratories Licensing Corporation (Dolby Laboratories Incorporated)
• Original Assignee: Dolby Laboratories Licensing Corporation (Dolby Laboratories Incorporated)
• Inventors: Orlick, Christopher John, Shields, Jerome D.
• Primary Examiner(s): Yenke, Brian P
• Application Number:
  US15/572,153
• Publication Number:
  US 20180146176A1
• Time in Patent Office: 1,313 Days
• CPC Class Codes: G02B 27/0025 for optical correction, e.g. distorsion, aberration
• CPC Class Codes: G02B 27/0927 Systems for changing the beam intensity distribution, e.g. Gaussian to top-hat
• CPC Class Codes: G03B 21/16 Cooling; Preventing overheating
• 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 21/206 Control of light source other than position or intensity
• CPC Class Codes: G06T 5/73 Deblurring; Sharpening
• CPC Class Codes: H04N 9/3126 for spatial light modulators in series
• CPC Class Codes: H04N 9/3144 Cooling systems cooling of liquid crystal cells in general G02F1/133382; cooling of projectors not peculiar to the presence of an electronic spatial light modulator G03B21/16
• 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

Abstract

Apparatus for controlling a spatial light modulator (106) of an image projector (100), the image projector further comprising an illumination source (102) arranged to illuminate the spatial light modulator (106), the apparatus comprising an input (126) for receiving image data, an output for outputting image data and a controller (110) in communication with the input and the output, the controller (110) being configured to:

• • determine an estimated thermal state of the projector;
  • use at least the estimated thermal state of the projector to obtain an expected illumination pattern of light incident on the spatial light modulator (106) when illuminated by the illumination source (102);
  • use the expected illumination pattern to adjust the received image data so as to compensate for thermal changes in one or more components of the image projector; and
  • output the adjusted image data to the spatial light modulator (106).

Claims

1. Apparatus for controlling a spatial light modulator of an image projector, the image projector further comprising an illumination source arranged to illuminate the spatial light modulator, the apparatus comprising:

an input configured to receive first image data corresponding to a frame of a video;

a controller in communication with the input, the controller configured to;

determine a thermal state of the projector based on the first image data,

generate a model lightfield based on the thermal state of the projector, the model lightfield representing an expected illumination pattern of light incident on the spatial light modulator when illuminated by the illumination source, and

generate second image data based on the first image data and the model lightfield, the second image data corresponding to the frame of the video; and

an output configured to output the second image data to the spatial light modulator.

2. The apparatus of claim 1 further comprising an input for receiving sensor data, wherein the controller is configured to determine the thermal state of the projector based on the received sensor data in addition to the first image data.

3. The apparatus of claim 1 wherein the sensor data comprises temperature data, and wherein the temperature data is indicative of at least one of:

a temperature within the illumination source;

an ambient temperature;

or a temperature of optics disposed between the illumination source and the spatial light modulator.

4. The apparatus of claim 1 wherein the controller is further configured to obtain a plurality of intensity values of the first image data, and is configured to use at least the obtained intensity values to determine the thermal state of the projector.

5. The apparatus of claim 4 wherein the controller is configured to determine the thermal state of the projector based on an average of the obtained intensity values in addition to the first image data.

6. The apparatus of claim 1 wherein the controller is configured to determine the thermal state of the projector based on a prior thermal state of the projector in addition to the first image data.

7. The apparatus of claim 1 wherein the illumination source comprises a plurality of emitters arranged in a plurality of groups, each of the groups being associated with a respective portion of the expected illumination pattern.

8. The apparatus of claim 7 wherein the controller is configured to determine respective thermal states of the groups of emitters, and wherein the controller is further configured to determine the thermal state of the projector based on the respective thermal states of the groups of emitters in addition to the first image data.

9. The apparatus of claim 8 wherein the controller is further configured to obtain, from a plurality of different points spread functions, a point spread function which is associated with the thermal state of the projector, and wherein the controller is configured to use at least the obtained point spread function to generate the model lightfield.

10. The apparatus of claim 9 wherein the controller is configured to obtain, from the plurality of different points spread functions, a point spread function which is associated with a group of the plurality of groups, and wherein the controller is configured to use at least the obtained point spread function to generate the model lightfield.

11. The apparatus of claim 9 wherein the controller is further configured to obtain, from the plurality of different points spread functions, respective point spread functions associated with the respective thermal states of the groups of emitters,

wherein the controller is further configured to convolve the obtained point spread functions, and

wherein the controller is configured to use at least the convolution of the obtained point spread functions to generate the model lightfield.

12. The apparatus of claim 9 wherein each of the point spread functions has a shape which depends at least on the thermal state with which it is associated.

13. An illumination projector comprising:

an apparatus according to claim 1;

an illumination source;

a spatial light modulator; and

optics disposed between the illumination source and the spatial light modulator.

14. A non-transitory, electronically-readable medium having code embodied therein which, when executed by a processor, will configure, in accordance claim 1, an apparatus for controlling a spatial light modulator of an image projector.

15. Apparatus for controlling a spatial light modulator of an image projector, the image projector further comprising an illumination source arranged to illuminate the spatial light modulator, the apparatus comprising:

an input configured to receive first image data corresponding to a frame of a video;

a controller in communication with the input, the controller configured to;

determine a thermal state of the projector based on the first image data,

select a point spread function based on the thermal state of the projector,

generate a model lightfield based on the thermal state of the projector and the point spread function, the model lightfield representing an expected illumination pattern of light incident on the spatial light modulator when illuminated by the illumination source, and

generate second image data based on the first image data and the model lightfield, the second image data corresponding to the frame of the video; and

an output configured to output the second image data to the spatial light modulator.