| 摘要 |
In one embodiment of the present invention, an active matrix liquid crystal device includes an active matrix substrate and a counter electrode substrate separated by a layer of liquid crystal material. A temperature sensing capacitor includes electrodes on the substrates separated by the liquid crystal layer, which thus forms the dielectric of the capacitor. A reference capacitor and a calibration capacitor are also provided and have nominally the same capacitance. These capacitors form part of charge-transfer capacitance measuring branches within a sample/hold circuit. During a calibration cycle, the sample/hold circuit provides a signal dependent on the difference between the capacitances of the calibration capacitor and the reference capacitor and this is supplied to an analog/digital converter, which forms a reference voltage. During subsequent parts of the measurement cycle, the converter converts the output of the sample/hold circuit using the reference voltage in order to improve the accuracy of measurement of the liquid crystal capacitor, and hence the temperature of the liquid crystal material. This temperature measurement may be used, for example, to compensate the AMLCD for the effects of temperature variation in the liquid crystal properties.
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