Low power photocontrol for luminaire
First Claim
1. A photocontrol apparatus to selectively provide alternating current (AC) power from an AC power source to a luminaire, the photocontrol apparatus comprising:
- an ambient light sensor having an output terminal which provides a signal responsive to an amount of light sensed by the ambient light sensor;
an ambient light detection circuit including an input terminal and an output terminal, the input terminal electrically coupled to the output terminal of the ambient light sensor, the output terminal of the ambient light detection circuit provides an ambient light control signal which has a luminaire-on state and a luminaire-off state, the luminaire-on state indicates an ambient light level detected by the ambient light sensor is at a level such that AC power is to be provided to the luminaire, the luminaire-off state indicates the ambient light level detected by the ambient light sensor is at a level such that AC power is not to be provided to the luminaire;
an AC sense circuit having an input terminal and an output terminal, the input terminal of the AC sense circuit electrically coupleable to the AC power source, the output terminal provides an AC sense signal indicative of at least one characteristic of the AC power source;
a switch including an input terminal, an output terminal and a control terminal, the input terminal electrically coupleable to a line terminal of the AC power source, the output terminal electrically coupleable to a load terminal of the luminaire, the switch having a closed state in which the switch electrically couples the luminaire to the AC power source and an opened state in which the switch electrically decouples the luminaire from the AC power source; and
a switch control circuit having a first input terminal, a second input terminal and an output terminal, the first input terminal electrically coupled to the output terminal of the AC sense circuit to receive the AC sense signal therefrom, the second input terminal electrically coupled to the output terminal of the ambient light detection circuit to receive the ambient light control signal therefrom, and the output terminal of the switch control circuit electrically coupled to the control terminal of the switch to provide a switch control signal thereto, the switch control circuit;
detects a change of state of the ambient light control signal from the luminaire-off state to the luminaire-on state;
detects a zero-crossing of the AC power source based at least in part on the received AC sense signal; and
responsive to the detection of the zero-crossing of the AC power source, causes the switch to transition from the opened state to the closed state which causes AC power to be provided to the luminaire from the AC power source.
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Accused Products
Abstract
Photocontrol apparatus that controls a luminaire or other load such that the luminaire is switched on during nighttime hours and off during the daytime. The photocontrol consumes only microwatts of power in either the ON or the OFF state, unlike traditional relay- or triac-based photocontrols. The photocontrol does not require a voltage generating photo sensor to generate power for the photocontrol. A solar cell, semiconductor photo diode or photo diode string, cadmium sulfide cell, semiconductor ambient light sensor, etc., may be used as the sensor element. The photocontrol switches power to the load at the zero-crossing of an AC input voltage, which reduces inrush current and the switching currents caused by traditional photocontrols which may switch at any point on the AC input voltage waveform.
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Citations
30 Claims
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1. A photocontrol apparatus to selectively provide alternating current (AC) power from an AC power source to a luminaire, the photocontrol apparatus comprising:
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an ambient light sensor having an output terminal which provides a signal responsive to an amount of light sensed by the ambient light sensor; an ambient light detection circuit including an input terminal and an output terminal, the input terminal electrically coupled to the output terminal of the ambient light sensor, the output terminal of the ambient light detection circuit provides an ambient light control signal which has a luminaire-on state and a luminaire-off state, the luminaire-on state indicates an ambient light level detected by the ambient light sensor is at a level such that AC power is to be provided to the luminaire, the luminaire-off state indicates the ambient light level detected by the ambient light sensor is at a level such that AC power is not to be provided to the luminaire; an AC sense circuit having an input terminal and an output terminal, the input terminal of the AC sense circuit electrically coupleable to the AC power source, the output terminal provides an AC sense signal indicative of at least one characteristic of the AC power source; a switch including an input terminal, an output terminal and a control terminal, the input terminal electrically coupleable to a line terminal of the AC power source, the output terminal electrically coupleable to a load terminal of the luminaire, the switch having a closed state in which the switch electrically couples the luminaire to the AC power source and an opened state in which the switch electrically decouples the luminaire from the AC power source; and a switch control circuit having a first input terminal, a second input terminal and an output terminal, the first input terminal electrically coupled to the output terminal of the AC sense circuit to receive the AC sense signal therefrom, the second input terminal electrically coupled to the output terminal of the ambient light detection circuit to receive the ambient light control signal therefrom, and the output terminal of the switch control circuit electrically coupled to the control terminal of the switch to provide a switch control signal thereto, the switch control circuit; detects a change of state of the ambient light control signal from the luminaire-off state to the luminaire-on state; detects a zero-crossing of the AC power source based at least in part on the received AC sense signal; and responsive to the detection of the zero-crossing of the AC power source, causes the switch to transition from the opened state to the closed state which causes AC power to be provided to the luminaire from the AC power source. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A photocontrol apparatus to selectively provide alternating current (AC) power from an AC power source to a luminaire, the photocontrol apparatus comprising:
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an ambient light detection circuit which includes an output terminal which provides an ambient light control signal indicative of an luminaire-on state and a luminaire-off state, the luminaire-on state indicates an ambient light level detected by the ambient light detection circuit is at a level such that AC power is to be provided to the luminaire, the luminaire-off state indicates the ambient light level detected by the ambient light detection circuit is at a level such that AC power is not to be provided to the luminaire; an AC sense circuit electrically coupleable to the AC power source and which includes an output terminal which provides an AC sense signal indicative of at least one characteristic of the AC power source; a switch including an input terminal, an output terminal and a control terminal, the input terminal electrically coupleable to a line terminal of the AC power source, the output terminal electrically coupleable to a load terminal of the luminaire, the switch having a closed state in which the switch electrically couples the luminaire to the AC power source and an opened state in which the switch electrically decouples the luminaire from the AC power source; and a switch control circuit electrically coupled to the respective output terminals of the ambient light detection circuit and the AC sense circuit, and electrically coupled to the control terminal of the switch, the switch control circuit; detects a change of state of from the luminaire-off state to the luminaire-on state; detects a zero-crossing of the AC power source; and responsive to the detection of the zero-crossing of the AC power source, causes the switch to transition from the opened state to the closed state which causes AC power to be provided to the luminaire from the AC power source. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30)
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Specification