Projection apparatus

Patent metadata

Field	Value
Publication number	US-9703182-B2
Application number	US-201214353897-A
Country	US
Kind code	B2
Filing date	Oct 12, 2012
Priority date	Oct 27, 2011
Publication date	Jul 11, 2017
Grant date	Jul 11, 2017

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.

First claim

The invention claimed is:

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.

Assignees

• Dainippon Printing Co Ltd

Inventors

• Kurashige Makio

Classifications

• G03B21/008

  using micromirror devices · CPC title

• H04N9/3135

  Driving therefor · CPC title

• G03B21/2033

  LED or laser light sources · CPC title

• H04N9/3164

  using multiple light sources · CPC title

• G03B33/06

  by additive-colour projection apparatus · CPC title