Multi-zone lighting control system

Claim 2

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.

Claim 3

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.

Claim 4

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.

Claim 5

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.

Claim 6

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

Claim 7

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