Power calibration of multiple light sources in a display screen

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Quick Facts

Patent No.: US 9,053,659
App. No.: 13/154,387
Granted: Jun 9, 2015
Kind: B2

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Abstract

A display device with multiple light sources includes a detector that dynamically measures output intensities of the light sources as the light sources are producing light to cause an image to be formed on a display screen. A controller for the display device compares the measured output intensities with desired output intensities determined from factory-calibrated correlation values and adjusts the inputs to the light sources to compensate for drift and other similar effects, so that brightness uniformity among the multiple light sources can be achieved.

Claims (47)

1. A light-based display device, comprising:

a display screen;

pixels disposed in the display screen;

light sources for producing a first light that is conveyed to the pixels, wherein the pixels emit a second light distinct from the first light;

a detector positioned on a light source side of the pixels, wherein the detector measures output intensity of the first light produced by one or more of the light sources as correlated to an input current to the one or more of the light sources, wherein the first light measured by the detector is a portion of the first light not impinging on the pixels; and

a controller for modulating the input current to a first light source in accordance with desired output intensities as determined from the correlation of the measured output intensity of the first light produced by a second light source to the input current to the first light source;

wherein the detector measures at least a portional output intensity of the light produced by the light sources,

wherein the light sources are laser beam sources for producing laser beams, the system further comprising a beam splitter disposed in optical paths of the laser beams and directing a portion of the laser beams to the detector.

2. The device of claim 1 , wherein the laser beam sources include an imaging beam source operating in a first wavelength band and a servo beam source operating in a second wavelength band and the beam splitter includes a coating that transmits a portion of an imaging beam produced by the imaging beam source.

3. The device of claim 1 , further comprising a filter positioned in an optical path of the portion of the imaging beam between the beam splitter and the detector and configured to attenuate laser beams transmitted therethrough by variable amounts as a function of wavelength.

4. The device of claim 1 , wherein the detector has a gain setting.

5. The device of claim 1 , wherein the beam splitter has a first surface on which the coating is applied and a second surface, the portion of the imaging beam being directed through the first surface and then to the second surface.

6. The device of claim 5 , wherein the second surface has an anti-reflective coating.

7. The device of claim 5 , wherein the beam splitter is configured to refract light reflecting off the second surface away from the detector.

8. The device of claim 1 , further comprising a lens between the beam splitter and the detector for directing the portion of the laser beams onto a central region on the detector.

9. The device of claim 1 , further comprising: a rotating polygon having a plurality of mirrored facets, each mirrored facet causing the laser beams to be scanned across the display screen; and a reflective surface disposed in the optical paths of the laser beams between the beam splitter and the rotating polygon, wherein the beam splitter directs a remaining portion of the laser beams to the reflective surface, and a first distance between the beam splitter and the reflective surface is substantially equal to a second distance between the beam splitter and the detector.

10. The device of claim 9 , further comprising a housing for the portion of the laser beams directed to the detector and the detector, the housing isolating the portion of the laser beams directed to the detector from the rotating polygon and the reflective surface and isolating the remaining portion of the laser beams from the detector.

11. The device of claim 1 , wherein the laser beams are scanned across the display screen at intervals and the detector is switched to ground during the intervals and is switched to a detection mode between the intervals.

12. The device of claim 11 , wherein the detector is switched to ground for the entire time during the intervals and switched to the detection mode for part of the time between the intervals.

13. A method of controlling output intensities of excitation beams that are conveyed to a display screen to form an image on the display screen, comprising:

receiving a correlation table, the correlation table comprising:

a correlation of output brightness of a first pixel within a pixel layer to a viewer and output intensity of a first excitation source when exciting the first excitation source of the first pixel with a first input power setting, wherein the first excitation source is on the opposite side of the first pixel to the viewer, and wherein the first excitation source is of a frequency distinct from the first pixel, and where the first excitation source is exciting the first pixel; and

a correlation of output brightness of a second pixel within the pixel layer to the viewer and output intensity of a second excitation source when exciting the second excitation source of the second pixel with a first input power setting, wherein the second excitation source is on the opposite side of the second pixel to the viewer, and wherein the second excitation source is of a frequency distinct from the second pixel, and where the second excitation source is exciting the second pixel;

receiving a first feedback signal from a first detector when the first excitation source is excited with the first input power setting, wherein:

at least a portion of the output from the first excitation source is detected by the first detector, wherein;

at least a portion of the output from the first excitation source excites a first pixel;

the first feedback signal correlates to the output intensity of the first excitation source at the first input power setting;

the first detector is on the excitation source side of the first pixel; and

the first detector detects excitation intensity of the first excitation source;

comparing the first feedback signal from the first detector when the first excitation source is excited with the first input power setting, wherein the output intensity correlating to the first feedback signal to the output intensity in the correlation table associated with the first input power setting for the first excitation source is compared; and

adjusting the input power setting of the first or second excitation source upon the comparison.

14. The method of claim 13 , further comprising comparing desired output intensities of the second source output intensity to the second source input power, wherein the first source input power is adjusted up or down respectively, based on said comparing and the determined first source output intensity value at a first source input power.

15. The method of claim 13 , wherein a single detector is used to measure the output intensities of the first source excitation from the first source and the second source excitation from the second source, wherein the measurements are taken one at a time.

16. A non-transitory computer-readable storage medium comprising instructions to be executed by a processing unit of a display device to carry out the steps of: