Television – Video display – Projection device
Patent
1996-07-03
1998-12-08
Burgess, Glenton B.
Television
Video display
Projection device
348761, 348776, 349 25, 349 28, 349 37, H04N 912, H04N 916
Patent
active
058477780
ABSTRACT:
In a projection type video display device comprising a light writing type spacial light modulator, disturbances brought about by a resetting pulse and appearing in a projected picture as a black belt or beat are prevented. This is accomplished by causing the resetting pulse, which is to withdraw electric charges produced by incoming writing light and accumulated in spacial light modulator, to occur within a vertical blanking period synchronized with vertical synchronization signal.
Further, by changing the pulse width and the voltage of the resetting pulse in accordance with vertical synchronization frequency, pictures of a certain fixed brightness are made available against various vertical synchronization frequencies; and even with a high vertical synchronization frequency, projected pictures are never annoyed by such disturbance that is caused by a resetting pulse dislocated out of the vertical blanking period.
Further, by controlling the adjustments of the writing voltage to be applied to the spacial light modulator during the writing period and the resetting voltage to be applied to the spacial light modulator during the resetting period, the spread in characteristics of the spacial light modulator is compensated to provide a certain fixed contrast and .gamma. characteristic. Furthermore, in a video display device for full-color display, writing voltage and resetting voltage can be established independently corresponding to the respective three RGB primary colors, video outputs of any desired color temperature are obtainable by adjusting the balance of light emission among the three RGB colors.
REFERENCES:
patent: 5178445 (1993-01-01), Moddel et al.
patent: 5694182 (1997-12-01), Mitsuoka et al.
Kawakami Toshikazu
Kuratomi Yasunori
Miyai Hiroshi
Muto Yasuaki
Noguchi Hiroshi
Burgess Glenton B.
Matsushita Electric - Industrial Co., Ltd.
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