Projection video display
A projection video display that projects video image suppresses deterioration of its quality which is attributed to a change in an optical path of the video image. A video signal generator performs control such that a second subframe in an N-th frame in a left-eye image is displayed on DMDs and then a second subframe in an N-th frame in a right-eye image is displayed on the DMDs. Furthermore, the video signal generator performs control such that a displayed location is not changed on a screen and the same types of subframes are displayed at the time when frames are switched.
1. A projection video display comprising:
a video generator that generates video image;
an optical system that projects the video image onto a projection surface;
an optical path changer that changes a location at which the video image is displayed on the projection surface, the optical path changer being disposed in an optical path of the video image; and
a controller that controls the video generator and the optical path changer, based on a video input signal,
wherein the controller generates a left-eye video signal and a right-eye video signal, which are viewpoint images for three-dimensional (3D) video, from the video input signal,
the controller spatially splits an image indicated by signals of frames in each of the left-eye video signal and the right-eye video signal to generate signals indicating a plurality of types of subframes, each of the plurality of types of subframes is formed of images displayed on different pixel position in the split image,
the controller controls the optical path changer so as to maintain the location at which the video image is displayed on the projection surface before and after a time when a subframe in the left-eye video signal and a subframe in the right-eye video signal are switched, and
the controller controls the video generator such that, when a first frame is switched to a second frame, the type of a last subframe in the first frame and the type of a first subframe in the second frame are the same and are related to different viewpoint images.
2. The projection video display according to claim 1 , further comprising:
a shutter device that switches between a light transmitting state and a light shielding state, transmits the light of video image that reaches to a left eye or a right eye in the light transmitting state, and shields the light of video image in the light shielding state; and
an actuator that operates the optical path changer,
wherein a switching frequency of the shutter device is set to be the same as a driving frequency of the actuator, and
a phase difference between a switching waveform of the shutter device and a drive waveform of the actuator is set to 90 degrees.
3. The projection video display according to claim 2 , wherein
when a 3D video display mode in which 3D video containing videos for a plurality of viewpoints is displayed is switched to a normal mode in which video for a single viewpoint is displayed, a drive frequency of the actuator in the 3D video display mode is set to be the same as a drive frequency of the actuator in the normal mode.
4. The projection video display according to claim 1 , wherein
the video generator generates a signal indicating at least one type of a subframe through an interpolation process, which is a process for making interpolation based on two successive frames.
5. The projection video display according to claim 4 , wherein
the controller varies weights added to the two frames related to the interpolation process in accordance with display timings of the plurality of types of subframes, and
the video generator makes interpolation of weighting based on the weights in the interpolation process.
6. The projection video display according to claim 1 , wherein
the video generator generates a plurality of a same type of subframes for a single frame in each of the left-eye video signal and the right-eye video signal.
7. The projection video display according to claim 1 , wherein
the video input signal includes a first left-eye video signal, a second left-eye video signal, a first right-eye video signal, and a second right-eye video signal,
the video generator generates a subframe, which is a viewpoint image for a left eye and whose type is a first type, based on the first left-eye video signal,
the video generator generates a subframe, which is a viewpoint image for a left eye and whose type is a second type, based on the second left-eye video signal,
the video generator generates a subframe, which is a viewpoint image for a right eye and whose type is a first type, based on the first right-eye video signal, and
the video generator generates a subframe, which is a viewpoint image for a right eye and whose type is a second type, based on the second right-eye video signal.
8. The projection video display according to claim 1 , wherein
the optical path changer moves a part of the optical system in a direction crossing the optical path.
9. The projection video display according to claim 1 , wherein:
the image comprises a plurality of blocks including a plurality of pixels, and
each of the plurality of types of subframes is formed by a plurality of pixels located at relatively same position in each of the plurality of blocks.
10. The projection video display according to claim 9 , wherein
each of the plurality of blocks is formed by the plurality of pixels arranged in a two-dimensional matrix.