| 摘要 |
Improved signal modulating circuits for a light valve projector are disclosed which are capable of increasing the magenta efficiency of the projector. The projector has an input bar plate having slots, a deformable light modulating medium and an output bar plate having slots. The control circuits generate a first control signal for red and a second control signal for blue. The light modulating medium is modulated in accordance with the red and blue control signals. The control circuits enhance the magenta modulation of the light modulating medium by generating a third control signal for magenta. A first circuit provides a magenta control signal whenever there is a magenta component which is the result of simultaneous inputs from the red and blue signals. A separate signal level for magenta is derived from the red and blue signals and a separate magenta carrier frequency is used which will cause magenta light to pass through slots in the output bar plate. In a second circuit, a second harmonic blue carrier signal is added to the blue carrier signal. A beat frequency is formed between the second harmonic and the carrier frequency used for red. By this technique the magenta intensity is increased because the beat frequency provides modulation of the light modulating medium at a frequency which permits first order magenta to pass through the output bar plate. In the third circuit, the magenta carrier is produced by multiplication of the red and blue modulated carriers prior to being added to the horizontal deflection plates of the light valve projector. This circuit gives additional extra beat frequency emphasis in the magenta control signal applied to the light modulating medium.
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