Low cost step dimming interface for an electronic ballast
AssigneeUniversal Lighting Technologies, Inc.
InventorsWei Xiong, Thomas Lunn, Christopher Radzinski
Life of this patent
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Abstract
A step dimming interface is utilized to operate a load such as a gas discharge lamp. The dimming interface has first and second switches for determining when the gas discharge lamp operates at either a normal power level or a dimming power level. A rectifier circuit is connected to a control signal production circuit. By manipulating the first and second switches, the rectifier sends either a full-wave rectified signal or a half-wave rectified signal to the control signal production circuit which determines the output of the control signal production circuit. The control signal production circuit may be connected to an electronic ballast which varies the power level of the lamp according to this output.
Claims20
A dimming interface for use with an electronic ballast powering a gas discharge lamp, the electronic ballast including a ballast inverter circuit, the dimming interface comprising:
- first and second power input terminals for connecting an AC source;
- a first dimming switch coupled to the first power input terminal;
- a second dimming switch coupled to the second power input terminal;
- a rectifier circuit coupled to the first and second dimming switches, the rectifier circuit operative to generate a rectified output power signal for providing power to a ballast inverter circuit and to output a dimming interface signal for controlling the ballast inverter circuit;
- the rectifier circuit is responsive to manipulation of the first and second dimming switches to cause the dimming interface signal to be
- a half-wave rectified signal when each of the dimming switches is closed, and
- a full-wave rectified signal when one of the dimming switches is open and the other dimming switch is closed;
- a dimming control signal generator circuit operably coupled to the rectifier circuit to receive the dimming interface signal;
- and
- wherein the dimming control signal generator circuit is responsive to the dimming interface signal to generate a DC control signal, the DC control signal having a first value when the dimming interface signal is a half-wave rectified signal and having a second value when the dimming interface signal is a full-wave rectified signal.
A dimming interface for use with an electronic ballast powering a gas discharge lamp, the electronic ballast including an inverter circuit, the dimming interface comprising:
- first and second power input terminals for connecting an AC source;
- a rectifier circuit for rectifying a periodic AC signal from the AC source;
- a first dimming switch connected between one of the power input terminals and the rectifier circuit;
- a second dimming switch connected between one of the power input terminals and the rectifier circuit;
- a dimming signal generator circuit operably coupled to the rectifier circuit, the dimming signal generating including a pulse generating circuit operable to generate pulses at a first pulse frequency when one of the switches is open and the other switch is closed and to generate the pulses at a second pulse frequency when both switches are closed;
- and
- a reference signal production circuit operably coupled to the pulse generating circuit, the reference signal production circuit receiving the pulses and generating a DC reference signal having a first reference signal value when the pulses are transmitted at the first pulse frequency and a second reference signal value when the pulses are transmitted at the second pulse frequency.
A method of controlling a dimming level of a lamp, comprising:
- rectifying an AC signal to produce a rectified output signal, the rectified output signal being a half-wave rectified signal when the lamp is to be dimmed and being a full-wave rectified signal when the lamp is to be at full brightness;
- converting the rectified signal into a DC reference signal, the DC reference signal having a first level when the rectified output signal is a half-wave rectified signal and being at a second level when the rectified output signal is a full-wave rectified signal;
- transmitting the DC reference signal to an inverter operably associated with the lamp;
- and
- controlling one or more switches on the inverter according to the level of the DC reference signal.
Dependencies are inferred from the claim text.