The present invention relates generally to power supplies utilized in lighting control applications and, more specifically, to power supplies used to power internal dimmer circuits.
A common application for a light dimmer is a two wire connection. A block diagram of a typical two wire connection is shown in
Conventional power supplies for two line dimmers are often based on a linear analog approach, including different capacitor charging schemes with a linear post regulation. Examples of power supplies utilizing this approach are shown in U.S. Pat. Nos. 4,334,184; 4,504,778; 4,678,985; and 5,600,552. These designs have a number of drawbacks, including need for bulky components and inefficiency, as they continuously dissipate energy and draw current while the device is in its OFF state. The implementation cost of linear power supplies may also be high.
A switching power supply can avoid the above-noted problems. A switch mode power supply regulates by connecting high input voltage to the low voltage power supply circuit for a short period of time. In a common approach, when a power supply switching element (such as a transistor) turns on, energy is delivered to an inductor, and in some cases to the output capacitor and a load. When the transistor turns off, the stored energy in the inductor is delivered to an outnut filter capacitor and a load. When the transistor conducts, it operates at fill current with minimum voltage drop, which results in little wasted power.
The minimum operating voltage of the power supply switching device represents a design restriction which becomes critical for two wire lighting applications. As shown in
The present invention offers a solution that overcomes both of these problems.
The present invention addresses the above-noted problems by providing a switching power supply circuit in which the input voltage level is increased, thereby improving the performance of the switching power supply. A voltage multiplier such as a voltage doubler circuit is introduced between the load switching device and the input to the switching power supply. The voltage multiplier permits stable operation of the power supply even at low voltages.
According to an aspect of the invention, a power supply circuit for providing power to internal circuits of a lighting dimmer device is adapted to be connected to a source of potential; the power supply circuit includes a voltage multiplier, a switching power supply, and a linear post regulator. The voltage multiplier is adapted to be coupled to the source of potential to provide an output signal of at least double the source of potential; the switching power supply is coupled to the voltage multiplier to receive the multiplied voltage as an input. The linear post regulator is interposed between the switching power supply and the internal circuits of the dimmer device.
According to another aspect of the invention, a power supply circuit for connection to a lighting dimmer device is provided which includes a voltage doubler circuit, a filter circuit, a switching power supply, and a linear regulator circuit In one embodiment, the voltage doubler circuit includes a first stage having a first capacitor and a first diode, and a second stage having a second capacitor and a second diode. The switching power supply may include a feedback circuit, and may be a non-isolated power supply. In an embodiment, the dimmer device is variable between an OFF position and a full ON position, and the circuit is effective to provide power for operation of the switching power supply while the dimmer device is in the full ON position.
Referring to
In this embodiment, power supply 38 is a non-isolated switching power supply with feedback determining the output voltage. It will be appreciated that an isolated power supply may also be used. In addition, the input of circuit 40 may be connected to an AC source other than the line and load terminals as shown in
While the invention has been described in terms of specific embodiments, it is evident in view of the foregoing description that numerous alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, the invention is intended to encompass all such alternatives, modifications and variations which fall within the scope and spirit of the invention and the following claims.
This application claims the benefit of U.S. Provisional Application No. 60/730,981, filed Oct. 27, 2005.
Number | Name | Date | Kind |
---|---|---|---|
4334184 | Hauenstein | Jun 1982 | A |
4504778 | Evans | Mar 1985 | A |
4678985 | Moskin | Jul 1987 | A |
4684819 | Haag et al. | Aug 1987 | A |
5113120 | Scott et al. | May 1992 | A |
5475580 | Noro | Dec 1995 | A |
5600552 | McCavit et al. | Feb 1997 | A |
5801492 | Bobel | Sep 1998 | A |
6218787 | Murcko et al. | Apr 2001 | B1 |
6969959 | Black et al. | Nov 2005 | B2 |
7091672 | Steffie et al. | Aug 2006 | B2 |
20020057080 | Telefus et al. | May 2002 | A1 |
Number | Date | Country | |
---|---|---|---|
20070126366 A1 | Jun 2007 | US |
Number | Date | Country | |
---|---|---|---|
60730981 | Oct 2005 | US |