PROJECTOR

• US 20200132982A1
• Filed: 10/30/2019
• Published: 04/30/2020
• Est. Priority Date: 10/31/2018
• Status: Active Grant

• Current Assignee: Qisda Corporation
• Original Assignee: Qisda Corporation
• Inventors: CHIEN, CHIH-SHIUNG, LIN, MING-KUEN, WU, TSUNG-HSUN
• Granted Patent: US 11,513,340 B2
• Time in Patent Office: Days
• CPC Class Codes: B81B 2201/042 Micromirrors, not used as optical switches
• CPC Class Codes: G02B 26/0833 the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD G02B26/0825 takes precedence; micromechanical devices in general B81B
• CPC Class Codes: G02B 5/04 Prisms
• CPC Class Codes: G02B 5/045 Prism arrays
• CPC Class Codes: G03B 21/008 using micromirror devices
• CPC Class Codes: G03B 21/2066 Reflectors in illumination beam in projection beam G03B21/28

Abstract

A projector including a light source, a first prism, a second prism and a digital micro-mirror device (DMD) is provided. The light source emits light. The first prism includes a first surface, a second surface and a third surface which are connected to each other around the perimeter thereof, and the illumination light enters the first prism through the first surface. The second prism has a fourth surface and a fifth surface which are connected to each other, and the fourth surface faces the second surface of the first prism. The DMD faces the third surface. The illumination light sequentially passes through the first surface, is reflected by the second surface, passes through the third surface, and reaches the DMD. The DMD converts the illumination light into image light, and the image light sequentially passes through the third surface, the second surface, the fourth surface and the fifth surface. In the first prism, a first included angle between the first surface and the third surface is more than or equal to 105 degrees.

Claims

1. A projector, comprising:

a light source, for emitting illumination light;

a first prism, comprising a first surface, a second surface and a third surface which are connected to each other around the perimeter thereof, wherein the illumination light enters the first prism through the first surface;

a second prism, comprising a fourth surface and a fifth surface which are connected to each other, wherein the fourth surface faces the second surface of the first prism; and

a digital micro-mirror device (DMD), facing the third surface, wherein the illumination light sequentially passes through the first surface, is reflected by the second surface, passes through the third surface, and reaches the DMD;

the DMD converts the illumination light into image light, and the image light sequentially passes through the third surface, the second surface, the fourth surface and the fifth surface;

wherein, in the first prism, a first included angle between the first surface and the third surface is more than or equal to 105 degrees.

2. The projector according to claim 1, wherein a ratio of the thickness of the second prism to the thickness of the first prism is more than or equal to 0.54 and less than or equal to 1 in a first direction, and the first direction is parallel to a normal vector of the third surface.

3. The projector according to claim 1, wherein the DMD comprises a reflection surface which is substantially parallel to the third surface of the first prism.

4. The projector according to claim 3, further comprising:

a projection lens, comprising a light entering end and a light exiting end, wherein the light entering end is configured to receive the image light from the fifth surface, and the image light enters the projection lens from the light entering end and then is emitted from the light exiting end;

the third surface of the first prism is substantially parallel to the fifth surface of the second prism;

the third surface is separated from the fifth surface by a first distance, and the reflection surface is separated from the light entering end by a second distance; and

a ratio of the first distance to the second distance is more than or equal to 0.53 and less than 1.

5. The projector according to claim 3, wherein the DMD is a tilt &

roll DMD.

6. The projector according to claim 3, wherein a second included angle is formed between a main optical axis of the illumination light and the normal vector of the first surface of the first prism, and the projector further comprises:

an optical path compensation device, disposed between the light source and the first surface of the first prism; and

the illumination light is transmitted to the first surface through the optical path compensation device.

7. The projector according to claim 6, wherein the optical path compensation device comprises a light exiting surface;

the illumination light enters the optical path compensation device and then is emitted from the light exiting surface; and

a third included angle is formed between the normal vector of the light exiting surface and the main optical axis of the illumination light.

8. The projector according to claim 7, wherein the optical path compensation device, the light source and the first prism are substantially arranged along an axial line;

the main optical axis of the illumination light emitted by the light source is substantially parallel to the axial line, and the projector conforms to;

θ

2=θ

3×

G;

wherein θ

2 is the second included angle;

θ

3 is the third included angle; and

1.6≤

G≤

1.9.

9. The projector according to claim 7, wherein the optical path compensation device, the light source and the first prism are substantially arranged along an axial line;

the main optical axis of the illumination light emitted by the light source is substantially parallel to the axial line;

the first surface has a first end close to the DMD and a second end away from the DMD in the first direction, and the light exiting surface has a third end close to the DMD and a fourth end away from the DMD in the first direction;

in a second direction perpendicular to the first direction, the first end is far away from the light source relative to the second end, and the fourth end is far away from the light source relative to the third end; and

the second direction is perpendicular to the normal vector of the DMD.

10. The projector according to claim 6, wherein the optical path compensation device comprises a plano-convex lens having a plane connected to the first surface of the first prism.