Vari-lite, Inc.

John Henry Covington

James M Bornhorst

Thomas E Walsh

Randall D Garrett

John Mark Newell

A switch-mode power converter uses a digital signal processor (DSP) to control operation of power semiconductors through gate drive amplifiers, further using the DSP's internal analog-to-digital converters to measure necessary currents, voltages and timings within the main power circuit. Using values captured by the A-to-D converters, software controlling the DSP manipulates duty cycle and timing parameters of the main semiconductor switches to provide at least three different modes of operation for serving a wide range of lighting loads. This power system reduces the size, cost, and weight, of circuitry needed to operate stage lighting equipment. The DSP's microprocessor eliminates most of the complex and dedicated analog circuitry commonly used for electronic power conversion, and a common power circuit topology provides an identical hardware platform for each luminaire circuit. Overall reliability is enhanced because of the reduction in circuit complexity.

Universal power module

For energizing remote lamp loads subjected to indeterminate transmission losses, a current regulating power supply is described which delivers a regulated current to the load using for example, a full wave rectifier supplying an unfiltered pulsating voltage to a switching regulator controlled by a feedback loop incorporating a current sensing resistor and pulse width modulator. The supply has a substantially unity power factor, a self-quenching characteristic in the presence of circuit interruptions, and can deliver regulated current to a variety of lamp types.

Techniques for controlling remote lamp loads

A modular lamp power supply is adapted to provide lamp power supply signals to a plurality of different lamps, each lamp having different power requirements. The power supply can be reconfigured to supply power to a new group of lamps simply by replacing the power circuit modules within the supply chassis.

Modular lamp power supply system

A power converter for converting 60 Hertz line power to 20 kilohertz power for driving a low voltage incandescent lamp (42). A field effect transistor power switch section (12) is connected through bridge rectifiers (10, 32) for charging a capacitor filter (34) with the AC input power. A 20 kHz oscillator (38) drives a half-bridge inverter (36) for coupling the capactitor voltage to the lamp (42) as high frequency power. The conduction of the FET power switch (12) is controlled by a phase locked loop (16) for synchronizing the conduction with the zero crossing points of the AC cycle. A ramp generator (18) and a summing network (20) are responsive to a lamp intensity control (22) for changing the conduction duty cycle of the FET power switch (12) such that a desired lamp intensity is maintained.

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Carrollton, TX, United States of America

John Henry Covington