Spectacle lens having continuously variable controlled density and fast response time
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United States of America Patent
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-
Jul 21, 1981
Grant Date -
N/A
app pub date -
Mar 25, 1980
filing date -
Mar 25, 1980
priority date (Note) -
Expired
status (Latency Note)
Importance
Abstract
A spectacle lens comprises a liquid crystal layer and electrode assembly sandwiched between a pair of identically curved glass plates and layers of polarization material on the outer surfaces of the plates. The optical density of the lens is controlled by applying across the electrodes variable duty cycle voltage pulses having a magnitude greater than a threshold voltage of the liquid crystal layer and a frequency at least as great as the critical flicker fusion frequency of the eye. The duty cycle of the pulses is controlled in response to ambient light intensity measured by a photocell. In order to reduce response time and increase operating lifetime of the liquid crystal layer, tir-level (+V, 0, -V) rather than bilevel (+V, 0) pulses may be applied to the liquid crystal electrodes.
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