Electricity: power supply or regulation systems – In shunt with source or load – Using a three or more terminal semiconductive device
Reexamination Certificate
2007-02-12
2009-08-04
Vo, Tuyet (Department: 2821)
Electricity: power supply or regulation systems
In shunt with source or load
Using a three or more terminal semiconductive device
C323S220000, C323S224000, C323S270000, C323S265000
Reexamination Certificate
active
07570031
ABSTRACT:
A two-wire load control device, such as a dimmer, is operable to control the amount of power delivered to an electrical load, such as a magnetic low-voltage (MLV) load, and comprises a bidirectional semiconductor switch, a timing circuit, a trigger circuit having a variable voltage threshold, and a clamp circuit. When a timing voltage signal of the timing circuit exceeds an initial magnitude of the variable voltage threshold, the trigger circuit is operable to render the semiconductor switch conductive, reduce the timing voltage signal to a predetermined magnitude less than the initial magnitude, and to increase the variable voltage threshold to a second magnitude greater than the first magnitude. The clamp circuit limits the magnitude of the timing voltage signal to a clamp magnitude between the initial magnitude and the second magnitude, thereby preventing the timing voltage signal from exceeding the second magnitude. Accordingly, multiple attempted firings of the semiconductor switch are avoided, and the MLV dimmer is prevented from conducting asymmetric current when an MLV transformer of the MLV load is unloaded.
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European Patent Office, International Search Report and Written Opinion, Aug. 30, 2007, 13 pages.
Lutron Electronics Co. Inc.
Rose Mark E.
Smith Philip N.
Vo Tuyet
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