Heater control method for liquid crystal devices

摘要

A nematic liquid crystal display device exhibits dielectric anisotropy when the device is in a normal operating temperature range. By placing electrodes on either side of the layer of liquid crystal material and applying across the material an electric field insufficient to change the molecular orientation in the material, the capacitance and therefore the dielectric constant of the material is measured. A similar measurement of dielectric constant is made with a strong electric field applied across the material such that the molecules are re-oriented unless the device is so cold that the molecular change cannot occur and the device is inoperative as a display. By comparing the dielectric constants, it is determined whether the device is at a suitable operating temperature and a heater for the device is controlled accordingly.