US-12619088-B2 - Laser projector with reduced optical elements and improved power efficiency

Abstract

A laser projector includes a light combining device, a light splitting system, a plurality of light valves, and a beam combiner. The light combining device is for emitting an illumination beam. The light splitting system is for receiving the illumination beam to generate a plurality of color beams. The plurality of light valves is for receiving and modulating the plurality of color beams to generate modulated color beams. The beam combiner is for combining the modulated color beams to form a full-color image.

Inventors

• Chun-Hao HU
• Tsung-hsun Wu
• Ching-Shuai Huang
• Ping-Chung Chou

Assignees

• QISDA CORPORATION

Dates

Publication Date

20260505

Application Date

20230717

Priority Date

20200320

Claims (20)

1. 1 . A laser projector comprising: a light combining device configured to emit an illumination beam, the light combining device comprising: a laser light source configured to provide a first light beam on a first optical path; a dichroic mirror having a surface, the dichroic mirror being disposed on the first optical path, the surface being configured to reflect a first portion of the first light beam, and allow a second portion of the first light beam to penetrate the dichroic mirror; only a single reflecting mirror disposed on the first optical path, and configured to reflect the second portion of the first light beam to the surface of the dichroic mirror, the surface of the dichroic mirror reflecting the second portion to a second optical path; and a wavelength converter configured to receive the first portion of the first light beam reflected from the surface and to emit a second light beam to the second optical path, the second light beam penetrating the dichroic mirror; wherein: the dichroic mirror is disposed between the laser light source and the reflecting mirror; the dichroic mirror, the laser light source and the reflecting mirror are aligned in a straight line; the second portion of the first light beam sequentially penetrates the dichroic mirror, being reflected by the reflecting mirror and being reflected by the dichroic mirror to the second optical path; and the second portion of the first light beam and the second light beam form the illumination beam on the second optical path; a light splitting system disposed on the second optical path, and configured to receive the illumination beam to generate a plurality of color beams; a plurality of light valves configured to receive and modulate the plurality of color beams to generate modulated color beams; and a beam combiner configured to combine the modulated color beams to form a multi-color image.
2. 2 . The laser projector of claim 1 , wherein the wavelength converter comprises phosphors or quantum dots.
3. 3 . The laser projector of claim 2 , wherein the wavelength converter is rotatable.
4. 4 . The laser projector of claim 1 , wherein the light splitting system comprises a polarization conversion system for converting the illumination beam to a polarized beam.
5. 5 . The laser projector of claim 1 , wherein the first light beam has a first waveband, the second light beam has a second waveband, and the first waveband is different from the second waveband.
6. 6 . The laser projector of claim 5 , wherein the first light beam is a blue light beam and the second light beam is a yellow light beam.
7. 7 . The laser projector of claim 5 , wherein: the first waveband comprises a first wavelength and a second wavelength different from the first wavelength; and the first light beam of the first wavelength penetrates the dichroic mirror with a first transmittance and the first light beam of the second wavelength penetrates the dichroic mirror with a second transmittance.
8. 8 . The laser projector of claim 7 , wherein the first transmittance is different from the second transmittance.
9. 9 . The laser projector of claim 1 , wherein the first optical path is perpendicular to the second optical path.
10. 10 . The laser projector of claim 1 , wherein the dichroic mirror and the first optical path intersect at a 45 degree angle.
11. 11 . A laser projector comprising: a light combining device configured to emit an illumination beam, the light combining device comprising: a laser light source configured to provide a first light beam on a first optical path; a dichroic mirror disposed on the first optical path, and configured to reflect a first portion of the first light beam, and allow a second portion of the first light beam to penetrate the dichroic mirror; only a single reflecting mirror disposed on the first optical path, and configured to reflect the second portion of the first light beam to the dichroic mirror, the dichroic mirror reflecting the second portion to a second optical path; and a wavelength converter configured to receive the first portion of the first light beam reflected from the dichroic mirror and to emit a second light beam to the second optical path, the second light beam penetrating the dichroic mirror; wherein: the dichroic mirror has positive transmittance and reflectance distributed uniformly on the dichroic mirror, and is disposed between the laser light source and the reflecting mirror; the dichroic mirror, the laser light source and the reflecting mirror are aligned in a straight line; the second portion of the first light beam sequentially penetrates the dichroic mirror, being reflected by the reflecting mirror and being reflected by the dichroic mirror to the second optical path; and the second portion of the first light beam and the second light beam form the illumination beam on the second optical path; a light splitting system disposed on the second optical path, and configured to receive the illumination beam to generate a plurality of color beams; a plurality of light valves configured to receive and modulate the plurality of color beams to generate modulated color beams; and a beam combiner configured to combine the modulated color beams to form a multi-color image.
12. 12 . The laser projector of claim 11 , wherein the wavelength converter comprises phosphors or quantum dots.
13. 13 . The laser projector of claim 12 , wherein the wavelength converter is rotatable.
14. 14 . The laser projector of claim 11 , wherein the light splitting system comprises a polarization conversion system for converting the illumination beam to a polarized beam.
15. 15 . The laser projector of claim 11 , wherein the first light beam has a first waveband, the second light beam has a second waveband, and the first waveband is different from the second waveband.
16. 16 . The laser projector of claim 15 , wherein the first light beam is a blue light beam and the second light beam is a yellow light beam.
17. 17 . The laser projector of claim 15 , wherein: the first waveband comprises a first wavelength and a second wavelength different from the first wavelength; and the first light beam of the first wavelength penetrates the dichroic mirror with a first transmittance and the first light beam of the second wavelength penetrates the dichroic mirror with a second transmittance.
18. 18 . The laser projector of claim 17 , wherein the first transmittance is different from the second transmittance.
19. 19 . The laser projector of claim 11 , wherein the first optical path is perpendicular to the second optical path.
20. 20 . The laser projector of claim 11 , wherein the dichroic mirror and the first optical path intersect at a 45 degree angle.

Description

CROSS REFERENCE TO RELATED APPLICATIONS This application is a continuation application of U.S. application Ser. No. 17/191,649, filed on Mar. 3, 2021. The content of the application is incorporated herein by reference. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is related to a laser projector, in particular to a laser projector that can reduce optical elements and improve efficiency. 2. Description of the Prior Art Projection systems require a high quality light source. While projection systems have traditionally used discharge lamps as a light source, there is now interest in alternative light sources such as lasers. Lasers have several advantageous properties. They emit a high intensity light beam and have a very long operating lifetime. However, laser projectors generally use blue light laser sources as illumination beams. The illumination beam needs to be converted into beams of other colors by a wavelength conversion device (such as a color wheel partially coated with phosphor or quantum dots), and then combined with the original illumination beam to be the projector light source. The traditional light combining module uses alight splitting system to reflect the illumination beam and then projecting it to the color wheel. The color wheel includes a wavelength conversion material to generate an excited light beam which can directly penetrate the light splitting system. In addition, part of the illumination beam passes through the part of the color wheel without wavelength conversion material, and returns to the beam splitter through a plurality of reflectors. The illumination beam is then reflected by the beam splitter to combine with the excited light beam. The traditional light combining module needs to be equipped with many optical components, which not only greatly add to the hardware cost, but also add to the weight and volume of the product. SUMMARY OF THE INVENTION An embodiment provides a laser projector including a light combining device, a light splitting system, a plurality of light valves, and a beam combiner. The light combining device includes a laser light source, a dichroic mirror, only a single reflecting mirror, and a wavelength converter. The laser light source is for providing a first light beam on a first optical path. The dichroic mirror has a surface and is disposed on the first optical path between the laser light source and the reflecting mirror. The surface is for reflecting a first portion of the first light beam. The second portion of the first light beam is allowed to penetrate the dichroic mirror. The reflecting mirror is disposed on the first optical path and is for reflecting the second portion of the first light beam to the surface of the dichroic mirror. The wavelength converter is for receiving the first portion of the first light beam reflected from the surface and emitting a second light beam to the second optical path. The second light beam penetrates the dichroic mirror. The second portion of the first light beam and the second light beam form the illumination beam on the second optical path. The light combining device is for emitting an illumination beam. The light splitting system is disposed on the second optical path for receiving the illumination beam to generate a plurality of color beams. The plurality of light valves is for receiving and modulating the plurality of color beams to generate modulated color beams. The beam combiner is for combining the modulated color beams to form a multi-color image. The dichroic mirror is disposed between the laser light source and the reflecting mirror. The dichroic mirror, the laser light source and the reflecting mirror are aligned in a straight line. The second portion of the first light beam sequentially penetrates the dichroic mirror, being reflected by the reflecting mirror and being reflected by the dichroic mirror to the second optical path. The second portion of the first light beam and the second light beam form the illumination beam on the second optical path. Another embodiment provides a laser projector including a light combining device, a light splitting system, a plurality of light valves, and a beam combiner. The light combining device includes a laser light source, a dichroic mirror, only a single reflecting mirror, and a wavelength converter. The laser light source is for providing a first light beam on a first optical path. The dichroic mirror is disposed on the first optical path between the laser light source and the reflecting mirror. The dichroic mirror is for reflecting a first portion of the first light beam. The second portion of the first light beam is allowed to penetrate the dichroic mirror. The reflecting mirror is disposed on the first optical path and is for reflecting the second portion of the first light beam to the dichroic mirror. The wavelength converter is for receiving the first portion of the first light beam reflected from the dichroic mirror and em