| 摘要 |
The device comprises an optical cell (20) which includes an optically active material, for example a liquid crystal, the transparency of which is a function of the electrical voltage applied, and a control circuit (22), characterised in that the said optically active material has an electrical impedance which can be varied with the frequency of the applied signal and in that the said control circuit comprises a voltage source and a means for controlling the frequency of the signal delivered by the said voltage source. Application as a light attenuator, especially for a sunroof or rear-view mirror for motor vehicles. <IMAGE>
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