Apparatus and method for dimming a gas discharge lamp

Patent 5949197 Issued on September 7, 1999. Estimated Expiration Date:

June 30, 2017. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.

Abstract Claims Description Full Text

Patent References

3683923

3708721

3746929

3868546

Dimming circuit with saturated semiconductor device
Patent #: 3936696
Issued on: 02/03/1976
Inventor: Gray

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Overcurrent and ground fault responsive trip unit for circuit breakers
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Issued on: 09/19/1978
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Fixed frequency, variable duty cycle, square wave dimmer for high intensity gaseous discharge lamp
Patent #: 4170747
Issued on: 10/09/1979
Inventor: Holmes

Non-interfering, overlapping high frequency signalling for lamp dimmer circuit
Patent #: 4220895
Issued on: 09/02/1980
Inventor: Nuver

Solid state electronic ballast system for fluorescent lamps
Patent #: 4251752
Issued on: 02/17/1981
Inventor: Stolz

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Inventor

Kastner, Mark

Assignee

Everbrite, Inc.

Application

No. 885438 filed on 06/30/1997

US Classes:

315/291, CURRENT AND/OR VOLTAGE REGULATION315/307, Automatic regulation315/362, ELECTRIC SWITCH IN THE SUPPLY CIRCUIT361/42Ground fault protection

Examiners

Primary: Philogene, Haissa

Attorney, Agent or Firm

Michael Best & Friedrich LLP

Foreign Patent References

0 596 740 EP. 05/12/1994
2 075199 JP. 03/12/1990
4 028199 JP. 01/12/1992
4 351889 JP. 12/12/1992
2 306 062 GB. 04/12/1997
WO 92 04809 WO. 03/12/1992

International Class

G05F 001/00

Abstract

A power supply for a gas discharge lamp includes a converter, a microprocessor switch control circuit, a driver, a switching network having two MOSFET switches, and an output transformer. A cross conduct inhibit circuit is connected in series between the driver and the switching network to prevent simultaneous operation of the switches. The power supply may further include a ground fault interrupt circuit and a ground continuity detector. A dimming module contains a potentiometer input device to vary the brightness of the lamp. The power supply operates at a preset level until the dimming module is connected. The dimming module cannot be removed without shutting off the power supply. The first and second MOSFETs switch first and second voltages across the transformer, thereby causing first and second drive pulses in the periodic output signal. Between the first and second and the second and first drive pulses are first and second dead times. The power supply sets the brightness level of the lamp by varying at least one of the dead time periods.