Dimmer switch with adjustable high-end trim
First Claim
1. A load control device with an adjustable high-end trim for controlling the amount of power delivered to an electrical load from an AC power source, the load control device comprising:
- a bidirectional semiconductor switch coupled in series electrical connection between the source and the load, and operable to control the amount of power delivered to the electrical load between a low-end trim and the adjustable high-end trim, the semiconductor switch having a control input for controlling the semiconductor switch in response to a firing voltage signal derived entirely from analog control circuitry; and
user-accessible means for reducing the adjustable high-end trim of the load control device from a first level to a second level lower than the first level, the user-accessible means for reducing having substantially no affect upon the low-end trim of the load control device.
4 Assignments
0 Petitions
Accused Products
Abstract
A dimmer switch has a user adjustable high-end trim. The dimmer switch includes a bidirectional semiconductor switch, such as a triac, for controlling the amount of power delivered from a source of alternating current power to a lighting load, such as an electric lamp. A user-adjustable timing circuit controls the conduction time of the triac from a minimum time to a maximum time. The maximum possible conduction time of the triac is the high-end trim. The minimum possible conduction time of the triac is the low-end trim. The timing circuit includes a user-accessible switch that allows a user to reduce the high-end trim from a first nominal level to a second reduced level, lower than the first level, without substantially affecting the low-end trim. The switch allows a user to switch a transient voltage suppressor into and out of parallel connection with a resistor that is part of an RC timing circuit for the triac. The dimmer switch advantageously uses less energy and the lifetime of the lamp is extended when the second reduced level of the high-end trim is selected.
18 Citations
41 Claims
-
1. A load control device with an adjustable high-end trim for controlling the amount of power delivered to an electrical load from an AC power source, the load control device comprising:
-
a bidirectional semiconductor switch coupled in series electrical connection between the source and the load, and operable to control the amount of power delivered to the electrical load between a low-end trim and the adjustable high-end trim, the semiconductor switch having a control input for controlling the semiconductor switch in response to a firing voltage signal derived entirely from analog control circuitry; and user-accessible means for reducing the adjustable high-end trim of the load control device from a first level to a second level lower than the first level, the user-accessible means for reducing having substantially no affect upon the low-end trim of the load control device. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
-
-
25. A timing circuit for allowing the adjustment of a high-end trim of a load control device, the timing circuit operable to generate a firing voltage signal, the load control device operable to control the amount of power delivered to an electrical load from an AC power source in response to the firing voltage signal, the timing circuit comprising:
-
a capacitor operable to conduct a charging current from the power source such that the firing voltage signal is produced across the capacitor; a potentiometer coupled to conduct the charging current of the capacitor, the potentiometer having a resistance variable between a minimum resistance and a maximum resistance for controlling the firing voltage signal; a first circuit for causing the firing voltage signal to increase from substantially zero volts to a predetermined voltage during a first amount of time when the potentiometer is set to the maximum resistance, and during a second amount of time when the potentiometer is set to the minimum resistance, the second amount of time less than the first amount of time; and a second circuit for causing the firing voltage signal to increase from substantially zero volts to the predetermined voltage during the first amount of time when the potentiometer is set to the maximum resistance, and during a third amount of time when the potentiometer is set to the minimum resistance, the third amount of time greater than the second amount of time, but less than the first amount of time; wherein the timing circuit is operable to selectively cause the firing voltage signal to increase from substantially zero volts to the predetermined voltage during either the second amount of time or the third amount of time each half-cycle of the AC voltage source when the potentiometer is set to the minimum resistance. - View Dependent Claims (26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41)
-
Specification