Compact optical projection apparatus

Patent metadata

Field	Value
Publication number	US-9756300-B2
Application number	US-201414537036-A
Country	US
Kind code	B2
Filing date	Nov 10, 2014
Priority date	Nov 20, 2013
Publication date	Sep 5, 2017
Grant date	Sep 5, 2017

Abstract

A compact optical projection apparatus. An apparatus for light projection includes at least one illumination device; a cover prism including a curved surface positioned to receive illumination light rays and a total internal reflection surface positioned to internally reflect the light rays towards an asymmetric reflector surface positioned opposite the total internal reflection surface, the asymmetric reflector surface configured to reflect the received light rays out of the cover prism at an emitter side of the cover prism; a spatial light modulating the illumination light rays with image data to form image light rays; a reverse total internal reflection (RTIR) prism positioned between the spatial light modulator and the emitter side of the cover prism and further comprising a total internal reflection surface configured to totally internally reflect the image light rays out of the RTIR prism into a light projection device. Additional apparatus are disclosed.

First claim

What is claimed is:

1. An apparatus for image projection, comprising:
at least one illumination device;
a cover prism comprising a curved surface positioned to receive illumination light rays emitted by the at least one illumination device, a total internal reflection surface positioned to internally reflect the light rays received through the cover prism towards an asymmetric reflector surface formed within the cover prism and positioned opposite the total internal reflection surface, the asymmetric reflector surface configured to reflect the received light rays back through the cover prism and out of an emitter surface of the cover prism;
a spatial light modulator having a surface for receiving illumination light rays from the emitter surface of the cover prism and configured for modulating the illumination light rays with image data to form image light rays; and
a reverse total internal reflection (RTIR) prism positioned between the spatial light modulator and the emitter surface of the cover prism and comprising an output surface positioned to allow illumination light rays emitted from the cover prism to travel through the RTIR prism to the spatial light modulator, and further comprising a total internal reflection surface positioned to receive the image light rays reflected from the spatial light modulator and configured to totally internally reflect the image light rays from the output surface of the RTIR prism and into a light projection optics device;
the light projection optics device positioned to receive the image light rays from the output of the RTIR prism and to project the image light rays, wherein the light projection optics device comprises: a physical pupil; a series of optical elements arranged to direct the image light rays through the physical pupil; and at least one lens element, but no more than two lens elements, disposed in an image light path after the physical pupil to project the image light rays, wherein a height of each lens element disposed in the image light path after the physical pupil is less than a height of the tallest optical element in the series of optical elements.

2. The apparatus of claim 1 , and further comprising:
a wedge positioned between the cover prism and the RTIR prism and configured to transmit light rays from the emitter surface of the cover prism into the RTIR prism and towards the spatial light modulator.

3. The apparatus of claim 1 , wherein the cover prism is configured to provide a folded optical path between the illumination device and the spatial light modulator.

4. The apparatus of claim 1 , wherein the curved surface of the cover prism further comprises relay optics.

5. The apparatus of claim 1 , wherein the illumination light rays enter the cover prism in a first direction, and the image light rays exit the light projection optics device in the same first direction.

6. The apparatus of claim 1 , wherein the cover prism is formed of a molded optical material that is one selected from the group consisting essentially of moldable glass materials and plastics including polycarbonate, PMMA, OCO, polystyrene.

7. The apparatus of claim 1 , wherein the cover prism further comprises a mirror surface formed on a portion of an exterior surface to form the asymmetric reflective surface.

8. The apparatus of claim 1 , wherein the RTIR prism further comprises a field lens disposed adjacent the output surface of the RTIR prism.

9. The apparatus of claim 8 wherein the field lens is adhered to the output surface of the RTIR prism.

10. The apparatus of claim 1 , wherein the at least one illumination device further comprises an illumination device that is one selected from the group consisting essentially of an LED, incandescent lamp, laser, and laser phosphor.

11. The apparatus of claim 1 , wherein the at least one illumination device further comprises at least three LEDs, one red, one green and one blue.

12. An in-line prism system for optical projection, comprising:
a cover prism having a portion that forms a curved surface for receiving illumination light rays from an illumination system, the cover prism further comprising a total internal reflection surface positioned opposite the portion and configured to reflect illumination light rays across the cover prism to an asymmetric reflective surface formed within the cover prism, the asymmetric reflective surface configured to reflect the illumination light rays back across the cover prism and out of the cover prism; and
an RTIR prism positioned to receive the illumination light rays from the cover prism and to emit the illumination light rays to a spatial light modulator positioned adjacent a first surface of the RTIR prism, and further comprising a total internal reflective surface positioned opposite the spatial light modulator and configured to receive image light rays from the spatial light modulator and to reflect the image light rays out of a second surface of the RTIR prism towards projection optics; and
the projection optics positioned to receive the image light rays from the second surface of the RTIR prism and to project the image light rays, wherein the projection optics comprise: a physical pupil; a series of optical elements arranged to direct the image light rays through the physical pupil; and at least one lens element, but no more than two lens elements, disposed in an image light path after the physical pupil to project the image light rays, wherein a height of each lens element disposed in the image light path after the physical pupil is less than a height of the tallest optical element in the series of optical elements;
wherein the illumination light rays enter the cover prism in a first direction, and the image light rays exit the RTIR prism in the same first direction and aligned with the illumination light rays.

13. The in-line prism system of claim 12 , and further comprising a wedge prism disposed between the cover prism and the RTIR prism.

14. The in-line prism system of claim 12 , wherein the portion that forms a curved surface of the cover prism further comprises an optical relay component.

15. The in-line prism system of claim 12 , wherein the cover prism comprises a molded material that is one selected from the group consisting essentially of moldable glass materials and plastics including polycarbonate, PMMA, OCO, polystyrene.

16. A portable device having an embedded compact optical projection system, comprising:
a processor having digital video output signals for display as an image;
a spatial light modulator coupled to the processor for converting the digital video output signals into images for projection by modulating illumination light;
at least one illumination source configured to emit illumination light rays;
a cover prism positioned to receive the illumination light rays into a curved surface, the cover prism further comprising a total internal reflection surface disposed to receive the illumination rays and to reflect the light rays at a 90 degree angle, and an asymmetric reflective surface within the cover prism positioned opposite the total internal reflection surface and configured to reflect the illumination light rays back across and out of the cover prism towards a spatial light modulator;
the spatial light modulator configured to receive the illumination light rays and for reflecting the illumination light rays modulated with images for projection to form image light rays; and
an RTIR prism positioned between the cover prism and the spatial light modulator and configured to receive the image light rays through a first surface adjacent the spatial light

Assignees

• Texas Instruments Inc

Inventors

• Sheng Zhongyan

Classifications

• H04N9/3173 Primary

  wherein the projection device is specially adapted for enhanced portability · CPC title

• G03B21/2013

  Plural light sources · CPC title

• G02B19/0066

  in the form of an LED array · CPC title

• G03B21/2033

  LED or laser light sources · CPC title

• H04N9/3176

  wherein the projection device is incorporated in a camera (details of cameras adapted for combination with a projector not peculiar to the presence of an electronic spatial light modulator G03B17/54) · CPC title