Liquid crystal element driving apparatus
First Claim
1. An apparatus for driving a liquid crystal element, mounted on a vehicle, comprising:
- a feedback control type voltage booster circuit, for connecting to a battery of said vehicle, for producing an output voltage that can be greater than the voltage of said battery said output voltage being a function of a control voltage applied to said voltage booster circuit;
a thermistor having a predetermined temperature resistance characteristic for sensing the temperature of said liquid crystal element by changing its resistance value according to said predetermined temperature-resistance characteristic;
a voltage divider circuit including said thermistor as a component thereof for dividing said output voltage from said booster circuit to produce said control voltage which is coupled to said booster circuit, said voltage divider circuit being so formed as to decrease a change of said control voltage relative to a change in the resistance value of said thermistor so that the output voltage of said booster circuit is increased more sharply as the sensed temperature becomes low, thus providing a booster circuit output voltage that is a non-linear function of temperature; and
a driving circuit for driving said liquid crystal element with said booster circuit output voltage.
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Accused Products
Abstract
An apparatus for driving a liquid crystal element by an increased voltage and at a lowered frequency in conformity with temperature fall in the liquid crystal element so as to achieve complete driving of the element even in a low temperature range. In order to increase the driving voltage, the apparatus comprises a booster circuit for increasing a battery voltage, and a voltage divider circuit including an element-temperature sensor as a component thereof and serving to produce a control voltage by dividing the output voltage of the booster circuit. In such configuration, the booster circuit performs its operation in such a manner as to maintain constant the control voltage obtained from the voltage divider circuit.
47 Citations
12 Claims
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1. An apparatus for driving a liquid crystal element, mounted on a vehicle, comprising:
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a feedback control type voltage booster circuit, for connecting to a battery of said vehicle, for producing an output voltage that can be greater than the voltage of said battery said output voltage being a function of a control voltage applied to said voltage booster circuit; a thermistor having a predetermined temperature resistance characteristic for sensing the temperature of said liquid crystal element by changing its resistance value according to said predetermined temperature-resistance characteristic; a voltage divider circuit including said thermistor as a component thereof for dividing said output voltage from said booster circuit to produce said control voltage which is coupled to said booster circuit, said voltage divider circuit being so formed as to decrease a change of said control voltage relative to a change in the resistance value of said thermistor so that the output voltage of said booster circuit is increased more sharply as the sensed temperature becomes low, thus providing a booster circuit output voltage that is a non-linear function of temperature; and a driving circuit for driving said liquid crystal element with said booster circuit output voltage. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. An apparatus for driving a liquid crystal device mounted on an automobile comprising:
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a battery mounted on said automobile; a temperature sensing element for sensing temperature of said liquid crystal device; a booster circuit connected to said battery for providing an output voltage that is a function of a control voltage applied thereto, said output voltage, which voltage can be greater than said battery voltage; a divider circuit connected in such a manner between said booster circuit and said temperature sensing element it provides said control voltage to said booster circuit causing said booster circuit to provide its output voltage such that it changes more sharply with respect to the sensed temperature as the temperature of said liquid crystal device falls; and a circuit connected betweeen said booster circuit and said liquid crystal device for driving said liquid crystal device with the output voltage of said booster circuit. - View Dependent Claims (11, 12)
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Specification