| 摘要 |
FIELD: mechanical engineering. SUBSTANCE: device is switchable from dark state of high light absorption degree to transparent state of low light absorption degree and in the opposite way. The device has slightly twisted liquid crystal cells of nematic type having twisting angle between 0 deg and a value slightly less than 90 deg, power supply source, electronic circuit producing measurable voltage exciting a cell. The voltage is twice as large as the threshold voltage of at least one of the liquid crystal cells. Polarity switch frequency is less than 1 Hz. EFFECT: variable permeability density; improved angular properties; low power consumption. 23 cl, 8 dwg
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