North American Philips Corporation

U.S. Philips Corporation

Edward H Stupp

Mark W Fellows

Babar Ali Khan

Walter G Steneck

Gert W Bruning

Andrew A Turnbull

Emil Arnold

Merton Howard Crowell

Joseph J Lalak

Vincent J Spataro

Thomas M Marshall

Leonard R Guarnera

Mali Venkatesan

Eduardo S Vera

The capacitance of a pixel of an active matrix liquid crystal light valve is increased without reducing its optical transparency by adding polysilicon islands under the adjacent gate lines, degeneratively doping the islands to render them conductive under operating conditions, thermally oxidizing the islands to form dielectric layers, depositing gate lines over the dielectric layers to form extra capacitors, and connecting the islands to the adjacent pixel electrodes. Such active matrix displays are advantageously employed in a color projection TV to produce the separate red, blue and green components of a full color display.

Method of forming an active matrix electro-optic display device with storage capacitors

Active matrix electro-optic display device with storage capacitors and

The thin film switch of a pixel of an active matrix liquid crystal light valve is shielded from light by adding a light shielding layer of amorphous germanium or germaniums nitride in the interpixel area surrounding the pixel electrodes. Such active matrix displays are advantageously employed in a color projection TV to produce the separate red, blue and green components of a full color display.

Active matrix electro-optic display device with light shielding layer

A push-pull high voltage oscillator power supply circuit includes a parallel resonant LC circuit made up of a capacitor in parallel with the primary of an output transformer. The output power level of the oscillator is controlled or adjusted by gating a drive circuit of the oscillator in accordance with an appropriate timing scheme so as to control the power delivered to the load over a long time period. The drive circuit is switched on and off so as to control the transformer primary voltage by omitting a number of drive pulses, determined by the desired output pulse level, so that the oscillator self-oscillates and rings out with a decreasing amplitude of the self-oscillats and rings out with a decreasing amplitude of the self-oscillations, but never reaches a complete cut-off of the oscillations before the drive circuit is gated on to refresh the supply of energy to the oscillator. A circuit for monitoring the collector voltages of the switching transistors of the oscillator may be provided to inhibit the supply of drive pulses to the switching transistors when the collector voltages exceed a given voltage level. This limits the power dissipation in the switching transistors.

High frequency high voltage power supply with controlled output power

A high-voltage semiconductor device is set forth having a passivation scheme able to shelter the device from both external charges and internal charges. In particular, the distribution of electric fields in the device is altered to make it less vulnerable to the presence of internal charges.

Dielectric passivation

A push-pull high voltage oscillator power supply circuit includes a parallel resonant LC circuit made up of a capacitor in parallel with the primary of an output transformer. The output power level of the oscillator is controlled or adjusted by gating a drive circuit of the oscillator in accordance with an appropriate timing scheme so as to control the power delivered to the load over a long time period. The drive circuit is switched on and off so as to control the transformer primary voltage by omitting a number of drive pulses, determined by the desired output pulse level, so that the oscillator self-oscillates and rings out with a decreasing amplitude of the self-oscillations, but never reaches a complete cut-off of the oscillations before the drive circuit is gated on to refresh the supply of energy to the oscillator. A circuit for monitoring the collector voltages of the switching transistors of the oscillator may be provided to inhibit the supply of drive pulses to the switching transistors when the collector voltages exceed a given voltage level. This limits the power dissipation in the switching transistors.

A complementary Silicon-On-Insulator (SOI) Lateral Insulated Gate Rectifier (LIGR) is fabricated in a monocrystalline silicon layer provided on a major surface of a substantially insulating substrate. The monocrystalline silicon layer includes a number of adjacent, doped coplanar layer portions, with the complementary SOI LIGR device being formed of adjacent, contacting layer portions forming two complementary LIGR elements with a common source region. The common source region, as well as both of the drain regions of the device, are composed of regions of both the first and second conductivity types. In this manner, a simple, easily fabricated, balanced, high performance complementary LIGR structure is obtained in which undesired substrate currents are substantially eliminated.

Complementary silicon-on-insulator lateral insulated gate rectifiers

A complementary Lateral Insulated Gate Rectifier (LIGR) includes two complementary LIGR structures fabricated in adjacent surface-adjoining semiconductor wells of the same conductivity type in a semiconductor substrate. The two LIGR structures are of generally similar configuration, thus simplifying the manufacturing process, and the proposed design additionally permits the n-channel and p-channel LIGR structures to have comparable 'on' resistances. The two LIGR structures, otherwise isolated by a portion of the substrate separating the two semiconductor wells, are connected together by a common source electrode. The resulting complementary Lateral Insulated Gate Rectifier features a compact, integrated structure in which the 'on' resistances of both the n-channel and p-channel portions of the device are comparable.

Complementary lateral insulated gate rectifiers with matched 'on'

A current fed high frequency oscillator-inverter ballast circuit includes a parallel resonant tank circuit for driving a pair of series connected discharge lamps via a series ballast capacitor. A regenerative power supply switches on when a fluctuating main DC supply voltage drops below a given level thereby providing a constant level auxiliary DC supply voltage to the oscillator inverter to maintain oscillation and lamp operation. When the main DC supply voltage exceeds said given level, the regenerative power supply switches out. The oscillation frequency is f.sub.2 during operation of the main supply and automatically switches to a frequency f.sub.1 when the regenerative power supply takes over. The frequency shift is automatic during each half cycle of a 60 Hz AC supply and is in a direction so as to maintain lamp current relatively constant. A novel high frequency leakage transformer may be provided to couple the high frequency inverter to the discharge lamp load to provide both a current limiting (ballast) action and automatic control of the lamp heater current to maintain high efficiency operation.

High-frequency oscillator-inverter ballast circuit for discharge lamps

A variable high-frequency ballast circuit for igniting and operating energy saver discharge lamps includes a high frequency inverter that energizes the lamps with a given high frequency voltage at which reliable lamp ignition is assured. The lamp current is monitored so as to automatically increase the lamp operating frequency to an optimum value as soon as the lamps ignite.

Variable high frequency ballast circuit

A variable frequency current control circuit for one or more discharge lamps comprises a push-pull oscillator inverter having an inductance in the DC supply, a non-resonant coupling circuit for coupling the output of the oscillator inverter to the lamp (or lamps) and cycle-by-cycle frequency control of the oscillator in response to a lamp current sensor thereby to automatically control the impedance of the lamp ballast in a sense to regulate the lamp current.

Variable frequency current control device for discharge lamps

An electrophoretic display device is set forth having various electrode schemes in order to modulate transmission of light through the device. The electrophoretic particles of the suspension form an imaging structure relating to an array of small unit cells or pixels which are turned on or off by appropriate electrical signals. Accordingly, the pigment particles totally cover transparent electrodes, which condition can be changed by applying the appropriate electric field to the opposite electrode. By this structure, various alphanumeric displays can be constructed.

Electrode configurations for an electrophoretic display device

A lamp circuit having a push pull oscillator including an inductance in the D.C. supply, non-resonant coupling circuit to the lamp and cycle-by-cycle frequency control of the oscillator regulated by a lamp current sensor.

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Spring Valley, NY, United States of America

Edward H Stupp