Image projector and a light source for use in the projector

• US 20060268546A1
• Filed: 05/26/2006
• Published: 11/30/2006
• Est. Priority Date: 05/31/2005
• Status: Active Grant

• Current Assignee: Casio Computer Company Limited
• Original Assignee: Casio Computer Company Limited
• Inventors: Kurosaki, Hideyuki
• Granted Patent: US 7,591,559 B2
• Time in Patent Office: Days
• US Class Current: 362/235
• CPC Class Codes: G02B 6/0048 with stepwise taper
• CPC Class Codes: G02B 6/0068 Arrangements of plural sources, e.g. multi-colour light sources
• CPC Class Codes: G02B 6/4298 coupling with non-coherent light sources and/or radiation detectors, e.g. lamps, incandescent bulbs, scintillation chambers
• CPC Class Codes: G03B 21/2013 Plural light sources
• CPC Class Codes: G03B 21/2033 LED or laser light sources
• CPC Class Codes: G03B 21/208 Homogenising, shaping of the illumination light

Abstract

A light source comprising a prismoidal housing with inclined sides of a flight of steps and with a closed smaller base and an open larger base. The entire inner surface of the housing is made of an optically reflective material. A plurality of light emitting elements are arranged on the smaller base of the prismoidal housing and the respective risers of the steps of each flight such that the plurality of light emitting elements emit rays of light toward the open large base of the housing.

Claims

1. A light source comprising:

a prismoidal housing with inclined sides of a flight of steps and with a closed smaller base and an open larger base, the entire inner surface of the housing being made of an optically reflective material; and

a plurality of light emitting elements arranged on the smaller base of the prismoidal housing and the respective risers of the steps of each flight such that the plurality of light emitting elements emit rays of light toward the open large base of the housing.

2. The light source of claim 1, wherein the tread of the step closest to the open larger base of the housing has a maximum length among those of all the steps.

3. The light source of claim 1, wherein the respective treads of the steps formed on the inclined sides of the prismoidal housing are inclined so as to be divergent relative to an optical axis of the housing toward the open larger base of the housing, the optical axis passing through the centers of the smaller and larger bases of the housing.

4. The light source of claim 3, wherein the plurality of light emitting elements are disposed such that their emission axes are parallel to an optical axis of the housing passing through the centers of the smaller and larger bases of the housing.

5. The light source of claim 2, wherein the respective treads of the steps formed on the inclined sides of the prismoidal housing excluding those of the steps closest to the open larger base of the housing are convergent relative to the optical axis of the housing toward the open larger base of the housing and the treads of the steps closest to the open larger base of the housing are convergent and then divergent relative to the optical axis of the housing toward the open larger base of the housing.

6. The light source of claim 1, wherein the open larger base of the housing has an aspect ratio of 3:

4 to equalize a brightness distribution of rays of light passing through the housing.

7. The light source of claim 1, wherein the plurality of light emitting elements comprise ones emitting red, green and blue rays of light.

8. A projector comprising:

a light source comprising a prismoidal housing with inclined sides of a flight of steps and with a closed smaller base and an open larger base, the entire inner surface of the housing being made of an optically reflective material; and

a plurality of light emitting elements arranged on the smaller base of the prismoidal housing and the respective risers of the steps of each flight such that the plurality of light emitting elements emit rays of light toward the open larger base of the housing;

an optical driver for driving the plurality of light emitting elements of the light source to emit rays of light;

an optical modulator for forming an optical image based on rays of light emitted by the plurality of light emitting elements; and

a projection subunit for projecting the optical image formed by the optical modulator onto a display screen.

9. The projector of claim 8, wherein the tread of the step closest to the open larger base of the housing has a maximum length among those of all the steps.

10. The projector of claim 8, wherein the respective treads of the steps formed on the inclined sides of the prismoidal housing are inclined so as to be divergent relative to an optical axis of the housing toward the open larger base of the housing, the optical axis passing through the centers of the smaller and larger bases of the housing.

11. The projector of claim 10, wherein the plurality of light emitting elements are disposed such that their emission axes are parallel to an optical axis of the housing passing through the centers of the smaller and larger bases of the housing.

12. The projector of claim 9, wherein the respective treads of the steps formed on the inclined sides of the prismoidal housing excluding those of the steps closest to the open larger base of the housing are convergent relative to the optical axis of the housing toward the open larger base of the housing and the treads of the steps closest to the open larger base of the housing are convergent and then divergent relative to the optical axis of the housing toward the open larger base of the housing.

13. The projector of claim 8, wherein the larger open base of the housing has an aspect ratio of 3:

4 to equalize a brightness distribution of rays of light passing through the housing.

14. The projector of claim 8, wherein the plurality of light emitting elements comprise ones emitting red, green and blue rays of light.

15. The projector of claim 8, wherein the optical driver drives the plurality of light emitting elements in a time-divisional manner for emitting corresponding colored rays of light.