Projection-type display apparatus

• US 8,469,525 B2
• Filed: 12/22/2009
• Issued: 06/25/2013
• Est. Priority Date: 12/25/2008
• Status: Expired due to Fees

• Current Assignee: Mitsubishi Electric Corporation
• Original Assignee: Mitsubishi Electric Corporation
• Inventors: Kojima, Kuniko, Takeuchi, Hayato, Sasagawa, Tomohiro
• Primary Examiner(s): Epps, Georgia Y
• Assistant Examiner(s): CHOWDHURY, SULTAN U.
• Application Number:
  US12/644,731
• Publication Number:
  US 20100165301A1
• Time in Patent Office: 1,281 Days
• Field of Search: 353/20, 353/30, 353/31, 353/32, 353/37, 353/38, 353/84, 353/76, 353/98, 353/99, 353/102, 359/15, 359/19, 359/20, 359/563, 359/558, 359/568, 359/599, 359/27, 359/707, 348/771, 348/345, 348/745, 372/39, 372/92, 372 96- 99
• US Class Current: 353/102
• CPC Class Codes: G02B 27/48 Laser speckle optics
• CPC Class Codes: G02B 5/02 Diffusing elements; Afocal elements
• CPC Class Codes: G03B 21/2033 LED or laser light sources
• CPC Class Codes: G03B 21/2066 Reflectors in illumination beam in projection beam G03B21/28
• CPC Class Codes: G03B 21/208 Homogenising, shaping of the illumination light
• CPC Class Codes: H04N 9/3102 using two-dimensional electronic spatial light modulators micromechanical modulators as such G02B26/0833; liquid crystal modulators as such G02F1/13
• CPC Class Codes: H04N 9/3155 for controlling the light source light source control per se H05B35/00 – H05B47/00; control of an illumination source for displays in general G09G3/3406
• CPC Class Codes: H04N 9/3161 using laser light sources using laser beams scanning the display screen H04N9/3129

Abstract

A projection-type display apparatus that projects an image on a screen and performs image display includes at least one laser source that emits a coherent light beam, an illuminating optics that propagates the light beam emitted from the laser source into a predetermined optical path to guide the light beam to the screen, a reflective optical modulator that forms the image to be displayed on the screen on an illuminated surface illuminated by the light beam guided by the illuminating optics, and a projection optics that magnifies and projects the image formed on the illuminated surface of the reflective optical modulator on the screen. The illuminating optics includes a diffusion device, which diffuses the propagated light beam, and is arranged on a light propagation path near a conjugated position with the reflective optical modulator.

Claims

1. A projection-type display apparatus that projects an image onto a screen to perform image display, the projection-type display apparatus comprising:

at least one light source that emits a coherent light;

an illuminating optics that propagates a light flux emitted from the light source on a predetermined optical path to guide the light flux to the screen;

a light valve that forms the image to be displayed on the screen in an illuminated area that is illuminated by the light flux guided by the illuminating optics; and

a projection optics that magnifies and projects the image, which is formed in the illuminated area of the light valve, onto the screen, wherein

the illuminating optics comprising a first diffusion unit that diffuses the propagated light flux and is arranged on the optical path near a conjugated position with the light valve, and

a light intensity equalizing device that equalizes intensity distribution of the light flux emitted from the light source, and

a conjugated position with the light valve is near an exit surface of the light intensity equalizing device.

2. The projection-type display apparatus according to claim 1, wherein

the illuminating optics further comprises a second diffusion unit that diffuses the propagated light flux and is arranged on the optical path near a conjugated position with an incidence-side aperture of the projection optics.

3. The projection-type display apparatus according to claim 1, wherein

a conjugated position with an incidence-side aperture of the projection optics is near an incident surface of the light intensity equalizing device.

4. The projection-type display apparatus according to claim 2, wherein

the illuminating optics comprises a light intensity equalizing device that equalizes intensity distribution of the light flux emitted from the light source, and a relay lens group and a mirror group that guide the light flux emitted from the light intensity equalizing device to the light valve, and

the conjugated position with the incidence-side aperture of the projection optics is located near the relay lens group or the mirror group.

5. The projection-type display apparatus according to claim 2, wherein at least one of the first and second diffusion units comprises a holographic diffusion device.

6. The projection-type display apparatus according to claim 2, wherein at least one of the first and second diffusion unit is a scattering member that scatters the light flux.

7. The projection-type display apparatus according to claim 2, wherein at least one of the first and second diffusion units is formed of frosted glass.

8. The projection-type display apparatus according to claim 2, wherein at least one of the first and second diffusion units comprises a lens array, in which a plurality of lens elements is arrayed in a planar manner.

9. The projection-type display apparatus according to claim 1, wherein at least one of the first and second diffusion units comprises at least one roughened surface of surfaces of the incident surface and the exit surface of the light intensity equalizing device.

10. The projection-type display apparatus according to claim 4, wherein the second diffusion unit comprises at least one roughened surface of lens surfaces of the relay lens group.

11. The projection-type display apparatus according to claim 4, wherein the second diffusion unit is configured with at least one of lenses of the relay lens group.

12. The projection-type display apparatus according to claim 4, wherein the second diffusion unit comprises at least one diffusion film attached on at least one surface of lens surfaces of the relay lens group.

13. The projection-type display apparatus according to claim 4, wherein the second diffusion unit comprises at least one roughened surface of mirror surfaces of the mirror group.

14. The projection-type display apparatus according to claim 2, wherein at least one of the first and second diffusion units comprises an antireflection coating on its surface.

15. The projection-type display apparatus according to claim 1, wherein the light source is a laser source.

16. The projection-type display apparatus according to claim 1, wherein the light intensity equalizing device comprises a tube-shaped member that reflects the light flux on an inner surface thereof.

17. The projection-type display apparatus according to claim 1, wherein the light intensity equalizing device comprises a polygonal pillar-shaped member formed of a transparent material and reflects the light flux on an interface between the transparent material and atmosphere.

18. The projection-type display apparatus according to claim 1, wherein the light intensity equalizing device comprises a lens array, in which a plurality of lens elements in a planar manner.