Projection video display systems
First Claim
Patent Images
1. A projection system comprising:
- a light source;
a two-dimensional spatial light modulator device comprising a plurality of individually controllable modulation elements arranged as an array;
control means for receiving a video signal representative of an image to be projected;
means for individually accessing said modulation elements in response to said video signal;
means for directing a beam of light from said light source onto said modulator device;
a screen positioned to receive the beam from said light source after modulation by said light modulator device so as to display a projected image; and
means for varying the video signal so as to change the modulation characteristics of chosen ones of said modulation elements so that the projected image will be perceived by an observer viewing the projected image on the screen as being of substantially uniform intensity over the area of the screen.
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Abstract
A projection system of the kind in which beams of light are projected by a projector onto a screen and the beams are modulated by electronic video information is characterized in that means are provided to vary the intensity of the light falling on different parts of the screen so that to an observer viewing the screen the said light intensity will be perceived as being substantially uniform over substantially the whole are of the screen.
286 Citations
17 Claims
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1. A projection system comprising:
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a light source; a two-dimensional spatial light modulator device comprising a plurality of individually controllable modulation elements arranged as an array; control means for receiving a video signal representative of an image to be projected; means for individually accessing said modulation elements in response to said video signal; means for directing a beam of light from said light source onto said modulator device; a screen positioned to receive the beam from said light source after modulation by said light modulator device so as to display a projected image; and means for varying the video signal so as to change the modulation characteristics of chosen ones of said modulation elements so that the projected image will be perceived by an observer viewing the projected image on the screen as being of substantially uniform intensity over the area of the screen. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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- 8. A method of correcting spatially non-uniform amplitude response in a projection system comprising a projector, a spatial light modulator device comprising a plurality of individually controllable modulation elements arranged in an array, each array element being individually addressable by signals representative of portions of the video signal corresponding to a pixel of the displayed image, and a screen, the projector being responsive to said video signal to project a video image onto said screen, comprising the steps of deriving a measure of the amplitude response from different areas of the screen and using the measures thus derived to correct corresponding portions of the video signal which will address array elements corresponding to said different areas of the screen, the measures being derived by measuring received light amplitudes at a plurality of different positions corresponding to different viewing stations in front of said screen.
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12. A method of displaying an image using a projection system comprising a projector, a spatial light modulator device comprising a plurality of individually controllable modulation elements arranged in an array, each array element being individually addressable by signals representative of positions of the video signal corresponding to a pixel of the displayed image, and a screen upon which the projector directs a projected image in accordance with an input video image signal, comprising the steps of measuring the spatial variations in intensity response of the projection system and varying the intensity of the projected image falling on different parts of the screen so as to substantially reduce variations in said intensity response, characterized in that said step of measuring comprises performing a plurality of like measurements at different points in time, and combining the results of said measurements so as to reduce the effects thereon of temporal variations in intensity response.
- 13. A method of displaying a video signal comprising directing a light beam via a spatial light modulator device onto a display screen, said spatial light modulator device comprising an array of individually controllable modulation elements each individually addressable by signals representative of said video signal, and controlling the spatial light modulator device to variably modulate the light beam in dependence upon the video signal, the method being characterized in comprising the step of modifying the video signal in dependence upon a predetermined reference signal to change the modulation characteristics of chosen ones of said modulation elements so as to reduce effects of spatial variations in illumination efficiency in the beam, as displayed on the display screen as perceived by an observer.
Specification