| 摘要 |
The projector comprises a powerful light source (4), a colourless optical modulation device (5), a diffusing screen (6), a disc (8) carrying three colour filters, red, green and blue, which is driven by a motor (7), and means (2 and 3) which receive a composite video signal which simultaneously transmits three items of colour information. A chrominance decoder (2) decomposes the composite video signal into a luminance signal Y and two colour difference signals v and u. The values of these three signals are stored in three digital memories (15, 16 and 17) for a period corresponding to one frame of the scanned image. They are reread three times during the same period, they are dematrixed and the colour signals obtained, R, G and B are applied to an input of the colourless optical modulating device (5) so as to restore in succession a red image, a green image, and a blue image. A synchronising device (9) controls the motor (7) in such a way that the filter carried by the disc (8) colours each of these three images in synchronism with the three operations of reading from the memories (15, 16, 17) and controls a multiplexer (22) selecting one of the colour signals. Application to the projection onto a large screen of a colour television image transmitted in accordance with a method of simultaneous transmission: NTSC, PAL, SECAM, etc.
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