LOAD CONTROL DEVICE FOR USE WITH LIGHTING CIRCUITS HAVING THREE-WAY SWITCHES
First Claim
1. A load control device adapted to be coupled to a circuit including an AC power source, a load, and a single-pole double-throw three-way switch, the AC power source generating an AC line voltage for powering the load, the load control device comprising:
- first, second, and third electrical load terminals;
a first controllably conductive device having a conductive state in which the first controllably conductive device is controlled so as to deliver a desired amount of power to the load such that the load is in an on state, and a non-conductive state in which the first controllably conductive device is controlled so as to deliver substantially no power to the load such that the load is in an off state, the first controllably conductive device electrically coupled between the first load terminal and the second load terminal such that when the first controllably conductive device is in the conductive state and the load control device is coupled to the circuit, a current to the load flows between the first load terminal and the second load terminal;
a second controllably conductive device having a conductive state in which the second controllably conductive device is controlled so as to deliver a desired amount of power to the load such that the load is in the on state, and a non-conductive state in which the second controllably conductive device is controlled so as to deliver substantially no power to the load such that the load is in the off state, the second controllably conductive device electrically coupled between the first load terminal and the third load terminal such that when the second controllably conductive device is in the conductive state and the load control device is coupled to the circuit, the current to the load flows between the first load terminal and the third load terminal;
a first sensing circuit electrically coupled to the second load terminal and operable to sense a first voltage at the second load terminal, the first sensing circuit characterized by a first impedance substantially larger than an impedance of the load;
a second sensing circuit electrically coupled to the third load terminal and operable to sense a second voltage at the third load terminal, the second sensing circuit characterized by a second impedance substantially larger than the impedance of the load;
a resistor coupled between the second and third electrical load terminals, the impedance of the resistor substantially larger than the impedance of the load; and
a controller operable to cause a respective one of the first and second controllably conductive devices to be in the conductive state, the controller operatively coupled to the first and second sense circuits to determine the state of the load in response to the first and second sensing circuits.
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Accused Products
Abstract
A smart switch for control of a lighting load from an AC voltage source can replace any switch in a three-way lighting control system. The smart switch can be connected on the line-side or the load-side of a three-way system with a standard three-way switch in the other location. The switch includes two semiconductor switches to control the connected lighting load. The switch preferably includes two sensing circuits for detecting the voltages at two of the load terminals of the switch to determine the state of the connected three-way switch(s), and thus, the load.
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Citations
16 Claims
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1. A load control device adapted to be coupled to a circuit including an AC power source, a load, and a single-pole double-throw three-way switch, the AC power source generating an AC line voltage for powering the load, the load control device comprising:
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first, second, and third electrical load terminals;
a first controllably conductive device having a conductive state in which the first controllably conductive device is controlled so as to deliver a desired amount of power to the load such that the load is in an on state, and a non-conductive state in which the first controllably conductive device is controlled so as to deliver substantially no power to the load such that the load is in an off state, the first controllably conductive device electrically coupled between the first load terminal and the second load terminal such that when the first controllably conductive device is in the conductive state and the load control device is coupled to the circuit, a current to the load flows between the first load terminal and the second load terminal;
a second controllably conductive device having a conductive state in which the second controllably conductive device is controlled so as to deliver a desired amount of power to the load such that the load is in the on state, and a non-conductive state in which the second controllably conductive device is controlled so as to deliver substantially no power to the load such that the load is in the off state, the second controllably conductive device electrically coupled between the first load terminal and the third load terminal such that when the second controllably conductive device is in the conductive state and the load control device is coupled to the circuit, the current to the load flows between the first load terminal and the third load terminal;
a first sensing circuit electrically coupled to the second load terminal and operable to sense a first voltage at the second load terminal, the first sensing circuit characterized by a first impedance substantially larger than an impedance of the load;
a second sensing circuit electrically coupled to the third load terminal and operable to sense a second voltage at the third load terminal, the second sensing circuit characterized by a second impedance substantially larger than the impedance of the load;
a resistor coupled between the second and third electrical load terminals, the impedance of the resistor substantially larger than the impedance of the load; and
a controller operable to cause a respective one of the first and second controllably conductive devices to be in the conductive state, the controller operatively coupled to the first and second sense circuits to determine the state of the load in response to the first and second sensing circuits. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method for controlling a load in a circuit comprising a power source, the load, a load control device, and a single-pole double-throw three-way switch, the method comprising the steps of:
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providing first, second, and third electrical load terminals on the load control device;
providing a high impedance coupling between the second and third electrical load terminals, the high impedance substantially larger than the impedance of the load;
electrically coupling a first controllably conductive device between the first load terminal and the second load terminal, the first controllably conductive device having a conductive state in which the first controllably conductive device is controlled so as to deliver a desired amount of power to the load and a non-conductive state in which the controllably conductive device is controlled so as to deliver substantially no power to the load, the first controllably conductive device arranged such that when the first controllably conductive device is in the conductive state, a current through the load flows between the first load terminal and the second load terminal;
electrically coupling a second controllably conductive device between the first load terminal and the third load terminal, the second controllably conductive device having a conductive state in which the second controllably conductive device is controlled so as to deliver a desired amount of power to the load and a non-conductive state in which the second controllably conductive device is controlled so as to deliver substantially no power to the load, the second controllably conductive device arranged such that when the second controllably conductive device is in the conductive state, the current through the load flows between the first load terminal and the third load terminal;
controlling the first and second controllably conductive devices between the conductive state and the non-conductive state;
sensing a first voltage at the second load terminal;
sensing a second voltage at the third load terminal; and
determining the state of the load in response to the first and second voltages. - View Dependent Claims (15, 16)
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Specification