U.S. Philips Corporation

Alexander D Annis

Alan G Knapp

Jeremy N Sandoe

John M Shannon

Geoffrey Baker

Peter B Wolfs

In an active matrix display device having an army of electro-optic, e.g. liquid crystal, display elements (12) which are each connected in series with a two-terminal non-linear device (15), such as a MIM type thin film diode, between associated row and column address conductors (16,17), and are driven by a circuit, (20,22) to produce a display effect by applying a selection signal to each row address conductor in turn and data signals to the column address conductors, a selection signal comprising a voltage pulse signal whose magnitude is increased gradually and in a controlled fashion to a maximum selection voltage amplitude is used so as to reduce the extent of ageing in the non-linear devices and differential ageing effects on display elements driven to different levels over a period of use by reducing peak currents flowing through the non-linear devices. The rising edge of the selection pulse signal is suitably shaped, for example by ramping or stepping, for this purpose. When using a five level row drive waveform comprising positive and negative selection signals and a reset signal, the reset selection signal can be shaped in this way, preferably together with the selection signal of opposite polarity.

Active matrix display device and method of driving such

In operation of an active matrix display device comprising an array of display elements (12), for example liquid crystal elements, each connected in series with an associated two terminal non-linear switching device (30), e.g. a MIM, between row and column address conductors (22,24), and row and column driver circuits (40,43) for applying selection signals to each row conductor in turn and data signals to the column conductors, the data signals are applied for part only of the row address period and a row selection signal commences prior to the data signal and while a reference potential is applied to the column conductors whereby during a row address period a display element is initially charged to a level approaching the lower end of the display element's operational range of voltages and thereafter charged to the required level according to the data signal. Vertical cross-talk is reduced and peak current density through the non-linear devices is kept low, thereby avoiding the risk of damage.

Method of driving a matrix display device and a matrix display device

A radiation detector circuit including a pyroelectric detector element and field effect transistor amplifier means. In order to inhibit saturation of the amplifier means under conditions of large transients in the radiation input or progressive changes in radiation input of low magnitude, at least one ultra-low leakage non-linear device is connected in the part of the circuit including the gate electrode of the amplifier means and the detector element. In one embodiment a pair of picoampere diodes are reverse parallel connected across the detector element and the circuit is formed as a hybrid microcircuit device having three external terminal connections. In another embodiment the non-linear device is incorporated in a feedback path between the output side of an amplification stage and the detector element.

Growing community of inventors

Haywards Heath, United Kingdom

Alexander D Annis