| 摘要 |
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 generates a micro-amp power supply using the voltage generated across a high value resistor in series with an alternating current (AC) power line. 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. |
| 主权项 |
1. A photocontrol apparatus to provide a control signal to a high-impedance controller input used to control a delivery of power to a load device, the photocontrol apparatus comprising:
a resistor having a first node and a second node; a switch including a first node, a second node, and a third node, the first node electrically coupled to a line node of an alternating current (AC) power source and the third node electrically coupled to the first node of the resistor, wherein the second node of the resistor is an output node of the photocontrol that is electrically coupleable to the high-impedance controller input; a first capacitor having a first node and a second node, the first node of the first capacitor electrically coupled to the first node of the switch and the second node of the first capacitor electrically coupled to the third node of the switch; a direct current (DC) power supply circuit that includes:
a positive DC power supply node electrically coupled to the first node of the resistor;a negative DC power supply node;a second capacitor having a first node and a second node, the first node of the second capacitor electrically coupled to the positive DC power supply node and the second node of the second capacitor electrically coupled to the negative DC power supply node;a zener diode having a cathode and an anode, the cathode of the zener diode electrically coupled to the positive DC power supply node and the anode of the zener diode electrically coupled to the negative DC power supply node; anda diode having a cathode and an anode, the cathode of the diode electrically coupled to the second node of the resistor and the anode of the diode electrically coupled to the negative DC power supply node; a comparator including a first power supply input node, a second power supply input node, a first input node, a second input node, and an output node, wherein the output node is communicably coupled to the second node of the switch and one of the first and the second power supply input nodes of the comparator is electrically coupled to the positive DC power supply node of the DC power supply circuit and the other of the first and the second power supply input nodes of the comparator is electrically coupled to the negative DC power supply node of the DC power supply circuit; and an ambient light sensor having an output node electrically coupled to one of the first input node or the second input node of the comparator, the ambient light sensor at least partially causes a voltage level of the one of the first input node or the second input node to which the ambient light sensor is electrically coupled to change in response to the ambient light sensor being at least partially illuminated with light. |
