In one embodiment of the present invention, an
active matrix liquid crystal device (AMLCD) includes an
active matrix substrate including an
active matrix area and a counter
electrode substrate carrying a common
electrode whose
voltage may vary so as to reduce
liquid crystal degradation. A layer of
liquid crystal material is disposed between the substrates and a temperature measuring arrangement is provided on the active matrix substrate. This arrangement includes a
temperature sensing liquid
crystal capacitor which in turn includes a first
electrode formed on the active matrix substrate outside the image generating region of the active matrix area and separated from the common electrode, which forms the second electrode of the
capacitor, by the liquid
crystal layer, which forms the
capacitor dielectric. During operation of the active matrix, a measuring circuit repeatedly performs a precharging step, in which the capacitor is precharged to a fixed stable known
voltage magnitude, and a step in which a
signal representing the
capacitance is formed. For example, the charge stored in the capacitor may be charge-shared with a transfer capacitor to form thereacross a
voltage representing the
capacitance of the liquid
crystal capacitor and hence representing the liquid crystal temperature. The sampling is performed repeatedly, preferably in
synchronism with addressing performed by the active matrix of the device. The resulting
temperature measurement may be used, for example, to compensate the AMLCD for the effects of temperature variation in the liquid
crystal properties.