Apparatus and methods for dimming gas discharge lamps using electronic ballast

• US 6,181,072 B1
• Filed: 05/29/1997
• Issued: 01/30/2001
• Est. Priority Date: 05/29/1997
• Status: Expired due to Fees

• Current Assignee: EZ Lighting LLC
• Original Assignee: EZ Lighting LLC
• Inventors: Cha, Dean Heesung, Yung, Allen Wong, Leslie, Alexander D.
• Primary Examiner(s): VU, DAVID HUNG
• Application Number:
  US08/865,750
• Time in Patent Office: 1,342 Days
• Field of Search: 315/291, 315/292, 315/293, 315/294, 315/297, 315/307, 315/308, 315/DIG.4, 315/194
• US Class Current: 315/194
• CPC Class Codes: H05B 41/36 Controlling
• CPC Class Codes: H05B 41/3921 with possibility of light intensity variations
• CPC Class Codes: H05B 47/185 via power line carrier transmission
• CPC Class Codes: Y10S 315/04 Dimming circuit for fluorescent lamps

Abstract

Apparatus and method are provided for electronic ballasts control and dimming of gas discharge lamps such as fluorescent lamps. Conventional wiring is used, thereby permitting ready retrofit of existing installations. Circuits are provided in the electronic ballasts (typically in the lamp) and in a conventionally operated dimmer switch (typically installed on a wall). A user adjusts the dimmer switch in a conventional manner to achieve the desired level of dimming of the lamp. Such adjustments apply a corresponding control voltage in the dimmer switch circuit, causing a small notch to appear in the output voltage from the dimmer switch. The notch is demodulated by the circuitry in the ballast, and is used to control the brightness of the lamp or lamps.

Claims

1. A circuit for demodulating a signal capable of dimming one or more gas discharge lamps, including a charge storing device for dividing a notched input signal into two waveforms, said waveforms being phase-delayed with respect to each other such that one waveform constitutes a leading waveform and the other waveform constitutes a lagging waveform, and said lagging waveform is filtered to virtually eliminate said notch whereby said circuit provides substantially continuous, non-discrete levels of adjustment of said lamps.

2. A system for dimming one or more gas discharge lamps, including the combination of a dimmer switch circuit capable of generating a notch in the positive side of an output AC waveform, said notch having an amplitude, said dimmer switch circuit also including means for preventing a corresponding notch from being formed on the negative side of said AC waveform, said combination further including at least one electronic ballast associated with said lamp, said electronic ballast configured to process said amplitude of said notch each cycle of said waveform to substantially instantly adjust the brightness of said lamp continuously within a given range of brightness, and a single power wire connecting said dimmer switch and said electronic ballast.

3. The system of claim 2, in which said one or more lamps are fluorescent lamps.

4. The system of claim 2 or claim 3, including a plurality of said electronic ballasts associated with a corresponding plurality of said lamps, the brightness of two or more of said lamps being controlled by said dimmer switch circuit.

5. A method of dimming gas discharge lamps, including the steps of:

providing operating power to one or more gas discharge lamps across a single power wire;

creating a voltage notch with an amplitude in an input power waveform;

transmitting said voltage notch with said power waveform across said single power wire to an electronic ballast of said one or more gas discharge lamps; and

demodulating said amplitude of said voltage notch within one waveform cycle to substantially instantly control the output of said one or more gas discharge lamps.