Laser projector for removing speckle noise
A laser projector includes a laser light source; a two-dimensional light modulator which modulates light from the laser light source; and a projection optical system which projects images onto a display plane by expanding the light modulated by the two-dimensional light modulator. Shift of a display position of the two-dimensional light modulation element and shift of the projection optical system are performed in synchronization with each other so that display positions of the images on the display plane are made substantially identical to each other. Thereby, speckle noise is sufficiently removed, and high-grade images are displayed.
1. A laser projector, comprising:
a laser light source;
a two-dimensional light modulator for modulating light from the laser light source;
a projection optical system for projecting images on a display plane by expanding the light modulated by the two-dimensional light modulator;
a driver which shifts the projection optical system in a direction perpendicular to an optical axis of the light modulated by the two-dimensional light modulator or in a direction of the optical axis; and
a controller which controls the two-dimensional light modulator and the driver,
wherein the two-dimensional light modulator shifts a display position of an image in the two-dimensional light modulator,
a shift of a display position of the two-dimensional light modulator, and a shift of at least a part of the projection optical system are performed in synchronization with each other so that display positions of the images on the display plane are made identical to each other when the display position of the image in the two-dimensional light modulator is shifted, and
the controller controls the two-dimensional light modulator to change a pixel region of the two-dimensional light modulator, wherein each pixel of the display plane is displayed using a plurality of pixels spaced apart from each other by a distance corresponding to one pixel or more on the two-dimensional light modulator, and
the controller controls the driver to shift the projection optical system in the direction perpendicular to the optical axis or in the direction of the optical axis in synchronism with the change of the pixel region of the two-dimensional light modulator.
2. The laser projector according to claim 1 , wherein
the shift of the display position of the image in the two-dimensional light modulator is such that the two-dimensional light modulator receives a display signal to be switched by shifting the display position of the two-dimensional light modulator to shift the display position of the image in the two-dimensional light modulator in accordance with the display signal.
3. The laser projector according to claim 1 , wherein
the shift of the display position of the image in the two-dimensional light modulator is such that the shift of the display position of the image in the two-dimensional light modulator is performed in a unit of pixel arrays.
4. The laser projector according to claim 1 , wherein
the shift of the display position of the image in the two-dimensional light modulator is such that the two-dimensional light modulator receives a display signal to be switched by converting a resolution of an image to be displayed by the two-dimensional light modulator to shift the display position by switching the resolution of the image in accordance with the display signal, and
the projection optical system performs a zoom operation in synchronism with the operation of switching the resolution of the two-dimensional light modulator.
5. The laser projector according to claim 1 , further comprising:
an illumination optical system for illuminating the two-dimensional light modulator by guiding the light from the laser light source to the two-dimensional light modulator, wherein
the illumination optical system shifts an illumination region with respect to the two-dimensional light modulator in synchronism with the shift of the display position of the image in the two-dimensional light modulator.
6. The laser projector according to claim 1 , wherein
an area of an integrated display image obtained by time-integrating the images to be displayed on the display plane is set larger than an area of an instantaneous display image to be instantaneously displayed each time the display position of the image in the two-dimensional light modulator is shifted.
7. The laser projector according to claim 1 , wherein
the number of pixels of an integrated display image obtained by time-integrating the images to be displayed on the display plane is set larger than the number of pixels of the two-dimensional light modulator.
8. The laser projector according to claim 1 , wherein an output of the laser light source is lowered at the time of switching the display position of the image in the two-dimensional light modulator.
9. The laser projector according to claim 1 , further comprising:
a detector for detecting a change in a position of the laser projector during a display operation,
wherein the shift of the display position of the image in the two-dimensional light modulator, and the shift of at least the part of the projection optical system are performed in synchronization with each other so that display positions of the images on the display plane are made substantially identical to each other by compensating for the change in the position detected by the detector.
10. A laser projector, comprising:
a laser light source;
a two-dimensional light modulator for modulating light from the laser light source;
a projection optical system for projecting images on a display plane by expanding the light modulated by the two-dimensional light modulator;
a first driver which shifts the two-dimensional light modulator in a direction perpendicular to an optical axis of the light modulated by the two-dimensional light modulator;
a second driver which shifts the projection optical system in the first direction or in a second direction parallel to the optical axis; and
a controller which controls the two-dimensional light modulator, the first driver and the second driver,
wherein the two-dimensional light modular shifts a display position of an image in the two-dimensional light modulator,
a shift of a display position of the two-dimensional light modulator, and a shift of at least a part of the projection optical system are performed in synchronization with each other so that display positions of the images on the display plane are made identical to each other when the display position of the image in the two-dimensional light modulator is shifted, and
the controller controls the first driver to shift the two-dimensional light modulator in the first direction by a distance corresponding to two times the pixel pitch or more, and controls the second driver to shift the projection optical system in the first direction or in the second direction in synchronism with the shift of the two-dimensional light modulator.