Multi-zone lighting control system

• US 5,990,635 A
• Filed: 06/22/1998
• Issued: 11/23/1999
• Est. Priority Date: 04/11/1994
• Status: Expired due to Term

• Current Assignee: Lutron Technology Company LLC
• Original Assignee: Lutron Electronics Company Incorporated (Lutron Electronics)
• Inventors: Zaharchuk, Walter S., Ference, Jonathan H., Hausman, Donald F., Loar, John F., Spehalski, Robert S.
• Primary Examiner(s): Wong, Don
• Assistant Examiner(s): Lee, Wilson
• Application Number:
  US09/102,296
• Time in Patent Office: 519 Days
• Field of Search: 315/DIG. 4, 315/119, 315/287, 315/362, 315/295, 315/294, 315/DIG. 5, 315/293, 315/316, 315/324, 315/291
• US Class Current: 315/362
• CPC Class Codes: H05B 39/08 by shifting phase of trigger voltage applied to gas-filled controlling tubes also in controlled semiconductor devices in converters H02M5/00; with regulation G05F1/44
• CPC Class Codes: H05B 39/086 with possibility of remote control
• CPC Class Codes: H05B 47/155 Coordinated control of two or more light sources
• CPC Class Codes: H05B 47/165 following a pre-assigned programmed sequence; Logic control [LC]
• CPC Class Codes: H05B 47/18 via data-bus transmission
• CPC Class Codes: Y10S 315/04 Dimming circuit for fluorescent lamps

Abstract

A lighting dimmer for controlling the current through a lighting load includes circuitry for applying a predetermined dimming level control signal to a control circuit in response to the absence of a dimming level control signal and the cycling OFF and ON of a circuit breaker. The dimmer further includes voltage compensation circuitry for maintaining a constant lighting load current notwithstanding short-lived changes in nominal line voltage.

Claims

1. In a light dimmer adapted to control the current flow through a lighting load to selectively adjust the luminous output thereof, said light dimmer comprising a dimming circuit connected between a power source and said lighting load, said dimming circuit being responsive to a dimming level control signal applied to an input terminal thereof for selectively varying the RMS voltage across the lighting load, the improvement comprising:

(a) means for sensing an absence of said dimming level control signal on said input terminal;

(b) circuit breaker means for selectively switching power OFF and ON between said power source and said dimming circuit; and

(c) logic and control means operatively coupled to said sensing means and said circuit breaker means for applying a predetermined dimming level control signal to said control circuit in response to both an absence of said dimming level control signal on said input terminal and a cycling of said circuit breaker means OFF and then ON.

2. Voltage compensation apparatus adapted for use in a light dimming circuit for maintaining a substantially constant lighting load current notwithstanding short-lived changes in a nominal line voltage, said apparatus comprising:

(a) first means operatively connected to an A.C. voltage source for determining a first time interval representing the average time required for the A.C. waveform of said voltage source to reach a predetermined threshold level during each half cycle of a nominal operating period;

(b) second means operatively connected to the A.C. power source for determining during each half cycle of the waveform a second time interval representing the time required for the A.C. waveform to reach such predetermined threshold level;

(c) means for comparing the first and second time intervals during each cycle of the waveform and for producing an error signal representing the difference in such time intervals; and

(d) means responsive to said error signal for adjusting the RMS voltage across the lighting load at a substantially constant level notwithstanding short-lived variations in the amplitude of the A.C. waveform of the voltage source.

3. The apparatus as defined by claim 2 wherein said first and second determining means comprise a capacitive element and means for measuring the charging time of said capacitive element.

4. The apparatus as defined by claim 3 wherein said capacitive element has different values dependent upon the value of said nominal line voltage.

5. The apparatus as defined by claim 2 wherein said first and second determining means comprise a microprocessor.