Lutron Electronics Company, Inc.

Russikesh Kumar

Dragan Veskovic

Venkatesh Chitta

Lance Hollner

Nicholas Barbour

Stuart William Dejonge

David J Dolan

A two-wire dimmer for control of a lighting load from an alternating-current (AC) power source includes a semiconductor switch, a power supply, and a control circuit. The power supply includes an energy storage input capacitor that is able to charge only when the semiconductor switch is non-conductive. The control circuit continuously monitors the voltage on the input capacitor and automatically decreases the maximum allowable conduction time of the semiconductor switch when the voltage falls to a level that will not guarantee proper operation of the power supply. The dimmer of the present invention is able to provide the maximum possible conduction time of the semiconductor switch at high end (i.e., maximum light intensity) while simultaneously ensuring sufficient charging time for proper operation of the power supply, and hence, the dimmer.

Dimmer having a power supply monitoring circuit

Lighting control keypad

Control panel

A smart dimmer for controlling the intensity of a lighting load from a source of AC power is operable to replace one of the three-way switches in a standard three-way lighting system without the need to replace the other three-way switch with a unique accessory switch. A simple rewiring is needed in the wallbox of the remaining three-way switch. In the resulting three-way lighting system, the smart dimmer is always coupled between the lighting load and the source and the remaining three-way switch is coupled between either of the load terminals of the dimmer and an accessory terminal of the dimmer. The remaining three-way switch acts to either couple or decouple an AC voltage from the accessory terminal. The smart dimmer is operable to detect a change in the state at the accessory terminal and toggle the lighting load on or off as a result of the change in state.

Dimmer for use with a three-way switch

A dimmer circuit provides AC power to an inductive lighting load in series with the dimmer circuit. A bidirectional semiconductor switch has a control electrode with a control signal for determining the power provided to the load. The switch in normal operation is controlled to block voltage in first and second half-cycles of the AC voltage. In a failure mode it can block the AC voltage in only one half-cycle. A controller for the switch determines the failure mode of the switch occurs which can cause an asymmetry between the half-cycles and thus a DC voltage component. A power supply supplies power to the controller from across the dimmer circuit. The controller drives the switch into substantially full conduction during most of the half-cycle which the switch is able to control; and drive the switch into non-conduction for a period of time during that same half-cycle so as to reduce the DC voltage component to prevent excessive transformer heating. The power supply is provided with sufficient voltage from the AC voltage to enable the controller to continue to operate.

Two-wire dimmer with power supply and load protection circuit in the event of switch failure

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Jersey City, NJ, United States of America

Russikesh Kumar