DLP color projector

Patent metadata

Field	Value
Publication number	US-10785459-B2
Application number	US-201816235883-A
Country	US
Kind code	B2
Filing date	Dec 28, 2018
Priority date	Jan 19, 2018
Publication date	Sep 22, 2020
Grant date	Sep 22, 2020

Abstract

In described examples, a digital light processing color projector includes light emitters configured to collectively emit light at multiple wavelengths, multiple light directing elements forming an illumination path having at least one aperture stop, a micromirror array coupled to a substrate, an aperture located at the aperture stop, and a filter with a selected color transmittance profile located at or near the aperture stop. The light directing elements are configured to direct light towards the micromirror array as illumination light. An aperture width determines a diameter of the illumination light. A micromirror on-state reflects the illumination light as on-state light. The substrate reflects the illumination light as flat-state light. The light directing elements direct on-state light through the aperture to a projector output. The filter filters flat-state light in an overlap region of the on-state light and flat-state light, or an illumination light portion corresponding to overlap region.

First claim

What is claimed is:

1. A color projector, comprising:
a digital micromirror device (DMD);
a lens configured to output light from the color projector;
one or more light emitters configured to collectively emit light at multiple wavelengths;
multiple light directing elements forming an illumination path having at least one aperture stop, including a projector aperture stop between the DMD and the lens;
a micromirror array fixedly coupled to a substrate, the light directing elements configured to direct light towards the micromirror array as an illumination light cone, micromirrors in the micromirror array having an on-state and an off-state, the on-state configured to reflect the illumination light cone as an output of the color projector as on-state light, the substrate configured to reflect at least a portion of the illumination light cone as flat-state light;
an aperture located at the aperture stop, a diameter of the illumination light cone at least partially determined by a width of the aperture, the light directing elements configured to direct light through the aperture to an output of the color projector; and
a filter at or near the projector aperture stop, the filter having a color transmittance profile, the filter configured to pass at least a portion of the illumination light cone or of the flat state light when a diameter of the aperture enables the on-state light and the flat-state light to overlap in an overlapping region, the passed portion corresponding to the overlapping region.

2. The color projector of claim 1 , wherein the diameter of the aperture is selectable.

3. The color projector of claim 1 , wherein the filter is located at or near an illumination aperture stop between the light emitters and the micromirror array.

4. The color projector of claim 3 , wherein the filter is configured to pass an illumination portion of the illumination light cone, the illumination portion comprising flat-state light within the overlapping region after the illumination portion is reflected by the substrate.

5. The color projector of claim 1 , wherein the filter is configured to filter a portion of the flat-state light within the overlapping region.

6. The color projector of claim 1 , wherein the filter is located and sized not to filter a majority of the on-state light.

7. The color projector of claim 1 , wherein the filter is configured to filter a smaller portion of the on-state light outside the overlapping region than of the on-state light within the overlapping region, if the aperture has a maximum diameter.

8. The color projector of claim 1 , wherein the filter has a low transmittance in red wavelengths, and a higher transmittance in green and blue wavelengths.

9. The color projector of claim 1 , wherein a size of the filter at least partially depends on a maximum diameter of the aperture.

10. The color projector of claim 1 , wherein the transmittance profile enables the filter to filter different wavelengths of light with different transmittances.

11. A method of image projection, the method comprising:
focusing illuminating light having multiple wavelengths on a digital micromirror device (DMD);
selecting a portion of the illuminating light to project using the DMD;
filtering, using a color filter with a color transmittance profile, light included within an overlap region in which the portion and a flat-state light cone overlap each other, the flat-state light cone being illuminating light reflected by portions of the DMD other than micromirrors of the DMD, the filtering producing a filtered portion; and
projecting the filtered portion using a projector lens;
in which a brightness of the illuminating light at least partially depends on a diameter of an aperture, a size of the overlap region is controlled by the diameter of the aperture, and the color filter is located at an illumination aperture stop between: the illuminating light and the DMD; or at a projection aperture stop between the DMD and a projected image.

12. The method of claim 11 , wherein the illuminating light passes through the color filter if the color filter is located at the illumination aperture stop, and wherein the flat-state light cone passes through the color filter if the color filter is located at the projection aperture stop.

13. The method of claim 11 , wherein the filtering filters red wavelengths with a low transmittance, and filters green wavelengths and blue wavelengths with a higher transmittance.

14. The method of claim 11 , wherein the transmittance profile enables the color filter to filter different wavelengths of light with different transmittances.

15. The method of claim 11 , wherein a size of the color filter at least partially depends on a maximum diameter of the aperture.

16. The method of claim 11 , wherein, if the aperture has a maximum diameter, a transverse area of the portion outside the overlap region which is affected by the filtering is smaller than a transverse area of the portion inside the overlap region which is affected by the filtering.

17. The method of claim 11 , wherein the illuminating light includes red light, blue light, and green light.

18. The method of claim 11 , further comprising pulsing a red light source, a blue light source, and a green light source, so that the red light source is active at different times from the blue light source and the green light source, and the blue light source is active at different times from the green light source, the illuminating light including the light from the red, blue, and green light sources.

Assignees

• Texas Instruments Inc

Inventors

• Sheng Zhongyan
• Pettitt Gregory Scott

Classifications

• H04N9/3111

  for displaying the colours sequentially, e.g. by using sequentially activated light sources (sequential projection in colour photography G03B33/08) · CPC title

• G02B5/005

  Diaphragms (for cameras G03B9/02) · CPC title

• H04N9/3152

  for shaping the light beam (beam shaping per se G02B27/09) · CPC title

• G03B21/00

  Projectors or projection-type viewers; Accessories therefor (devices for changing pictures G03B23/00) · CPC title

• H04N9/3164 Primary

  using multiple light sources · CPC title