Projection apparatus

• US 9,703,182 B2
• Filed: 10/12/2012
• Issued: 07/11/2017
• Est. Priority Date: 10/27/2011
• Status: Expired due to Fees

• Current Assignee: Dai Nippon Printing Company Limited
• Original Assignee: Dai Nippon Printing Company Limited
• Inventors: Kurashige, Makio
• Primary Examiner(s): Chang, Audrey Y
• Application Number:
  US14/353,897
• Publication Number:
  US 20140253989A1
• Time in Patent Office: 1,733 Days
• Field of Search: 359 15, 359707, 359316, 359229, 353 37, 353 31, 353121, 345691, 345 88, 355 67, 332109
• CPC Class Codes: G02B 26/101 with both horizontal and vertical deflecting means, e.g. raster or XY scanners colour television using laser beams scanning a display screen H04N9/3129
• CPC Class Codes: G02B 27/48 Laser speckle optics
• CPC Class Codes: G03B 21/008 using micromirror devices
• CPC Class Codes: G03B 21/147 Optical correction of image distortions, e.g. keystone
• CPC Class Codes: G03B 21/2033 LED or laser light sources
• CPC Class Codes: G03B 21/208 Homogenising, shaping of the illumination light
• CPC Class Codes: G03B 33/06 by additive-colour projection apparatus
• CPC Class Codes: H03K 7/08 Duration or width modulation ; Duty cycle modulation
• CPC Class Codes: H04N 9/3135 Driving therefor
• CPC Class Codes: H04N 9/3164 using multiple light sources
• CPC Class Codes: H04N 9/3197 using light modulating optical valves

Abstract

A projection apparatus has an optical device capable of diffusing coherent light beams, an irradiation unit to irradiate coherent light beams to the optical device so that the coherent light beams scan the optical device, a light modulator to generate a modulated image using coherent light beams incident on and diffused at respective points of the optical device from the irradiation unit, and a projection optical system to project a modulated image generated by the light modulator onto a scattering plane. The light modulator has a plurality of micromirrors provided for each pixel, to switch a reflection angle of each coherent light beam from the optical device, and a reflection angle controller to control a timing of switching a reflection angle of each of the plurality of micromirrors so that the timing becomes irregular for each frame period that is a time unit for generating the modulated image.

Claims

1. A projection apparatus comprising:

an optical device configured to diffuse coherent light beams;

an irradiation unit configured to irradiate coherent light beams to the optical device so that the coherent light beams scan the optical device;

a light modulator configured to generate a modulated image using coherent light beams incident on and diffused at respective points of the optical device from the irradiation unit; and

a projection optical system configured to project a modulated image generated by the light modulator onto a scattering plane, the modulated image being a two-dimensional image,

wherein the light modulator comprises;

a plurality of micromirrors provided for each pixel, configured to switch a reflection angle of each coherent light beam from the optical device; and

a reflection angle controller including a pulse width modulation generator and a random number generator configured to adjust a reflection angle of each of the plurality of micromirrors for each frame period so that each timing at which the modulated image is begun to be projected onto the scattering plane is random for each frame period, the frame period being a time unit to generate the modulated image,

wherein the pulse width modulation generator comprises a plurality of image gradient storages which store image gradient data in accordance with the modulated image, each image gradient storage being provided corresponding to a different pulse width,

the random number generator generates the random number for each frame period,

the plurality of image gradient storages are reordered at random based on the random number for each frame period, and

the reflection angle controller adjusts the reflection angle of each of the plurality of micromirrors based on a pulse width modulation signal generated by the image gradient data stored in the plurality of image gradient storages read out on an alignment order of the plurality of image gradient storages for each frame period and the pulse widths corresponding to each of the plurality of image gradient storages.

2. The projection apparatus of claim 1, wherein the reflection angle controller controls a timing incident coherent light beams reflected by each of the plurality of micromirrors on the projection optical system so that the timing is random for each frame period.

3. The projection apparatus of claim 1, wherein the irradiation unit makes a plurality of coherent light beams of different wavelength ranges scan on the optical device while switching the plurality of coherent light beams sequentially in one frame period, and

the reflection angle controller controls a timing of switching a reflection angle of each of the plurality of micromirrors so that the timing is random for each frame period for each of the plurality of coherent light beams.

4. The projection apparatus of claim 3, wherein a plural number of micromirrors are provided for each pixel among the plurality of micromirrors,

the plurality of coherent light beams of different wavelength ranges are incident on the plural number of micromirrors provided for each pixel, respectively, and

the reflection angle controller controls a timing at which a reflection angle of a micromirror that corresponds to each of the plurality of coherent light beams is switched so that the timing is random for each frame period.

5. The projection apparatus of claim 1, wherein the irradiation unit makes a plurality of coherent light beams of different wavelength ranges simultaneously scan on the optical device,

the light modulator comprises a plurality of light modulating units on which a plurality of coherent light beams of different wavelength ranges diffracted by the optical device are incident, respectively,

each of the plurality of light modulating units comprises the plurality of micromirrors, and

the reflection angle controller controls a timing at which a reflection angle of each of the plurality of micromirrors that corresponds to each of the plurality of light modulating units is switched so that the timing is random for each frame period.

6. The projection apparatus of claim 1, wherein the optical device is a hologram recording medium, each point on the hologram recording medium being capable of reproducing an image on a position of the light modulator.

7. The projection apparatus of claim 1, wherein the optical device is a microlens array.

8. The projection apparatus of claim 1, wherein the irradiation unit comprises:

a plurality of light sources configured to emit coherent light beams of different wavelength ranges; and

a scanning device configured to change a propagation direction of the coherent light beams emitted from the plurality of light sources and make the coherent light beams scan on the optical device.