United Technologies Corporation

Edward L Young

Mohan L Kapoor

Thomas J Rebeschi

Michael H Kalmanash

The luminosity of electroluminescent display pixels arranged at intersection regions between row and column electrodes is controlled so as to compensate for the effect of interelectrode coupling by reducing the voltage differentials applied between the row electrode being addressed and the column electrodes relative to those coresponding to initial pixel luminosity data contained in an incoming data stream, as a direct function of total row luminosity information extracted from that segment of the incoming data stream which pertains to the respective row.

Electroluminescent display brightness compensation

A simplified row driver switching circuit for display panels and the like, including particularly electroluminescent (EL) panels, as well as plasma panels, using inductance coupling between the power supply and the row electrodes. The circuit limits energy transfer to each row electrode of the EL panel through the inductance coupling, minimizing the effects of destructive arcing caused by inter-electrode shorts. The circuit is energy conservative and eliminates the need for, for example, -160 V and +220 V power supplies. Two row driver circuits are disclosed (FIGS. 4 & 6), the latter allowing the row electrodes to be driven to negative, as well as positive, voltages. Inductor(s) (L of FIG. 4; L.sub.1 & L.sub.2 of FIG. 6) are used to store and transfer energy to the row electrode load (C.sub.panel) and then back to the power source (V.sub.in), as various switches are pulsed 'on' and released. The same power supply can be used for both the row driver and the column driver (FIG. 7).

Row driver for EL panels and the like with inductance coupling

A simplified row driver switching circuit for display panels and the like, including particularly electroluminescent (EL) panels, as well as plasma panels, using transformer coupling between the power supply and the row electrodes. The circuit limits energy transfer to each row electrode of the EL panel to minimize the effects of destructive arcing caused by inter-electrode shorts. The circuit is energy conservative and eliminates the need for, for example, -160V and +220V power supplies, and provides reduced stress levels for many components through transformer coupling, and all active switches are driven from ground potential. Two row driver circuits are disclosed (FIGS. 4 & 6), the latter, using a split primary coil and double sets of paired switches, allows the row electrodes to be driven to negative, as well as positive, voltages. The primary and secondary windings on the transformer (T.sub.1 of FIGS. 4 & 6) are used to store and transfer energy to the essentially capacitive row electrode load (C.sub.panel) and then back to the power source (V.sub.in), as various associated switches are pulsed 'on' and released. The same power supply can be used for both the row driver and the column driver (FIG. 8).

Row driver for EL panels and the like with transformer coupling

A color switch for a beam penetration CRT can display a randomly selected color in a first color write period, and immediately after the first color write period the magnetizing current in the high voltage transformer is reset during a second write period in a complementary color. A high voltage power supply has an output voltage selected to provide a baseline color whose voltage level is intermediate the voltage range of the CRT anode. A pair of drivers are connected to either end of the primary winding of the high voltage transformer and generate a voltage differentially across the primary winding that drives the voltage level either upwardly or downwardly from the baseline level. Immediately after the first color write period, a second color write period is formed in a complementary color by transitioning a pair of input switches. This causes the color switch to change to the voltage level on the opposite side of the baseline voltage level so that the flux level in the core of the transformer is reset to a balanced DC condition.

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Shelton, CT, United States of America

Edward L Young