The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Feb. 04, 2003
Filed:
Jun. 06, 2001
Alois Biebl, St. Johann, DE;
Abstract
A drive circuit for an LED array, comprising at least two clusters of LEDs, in which one cluster comprises a number of LEDs arranged in series which are connected to a supply voltage (U ), with a semiconductor switch (T) being arranged in series between each LED cluster and the associated supply voltage, which semiconductor switch (T) allows the LED current to be supplied in a pulsed manner, with a measurement resistor (R ) being arranged in series with the LEDs in the path for the forward current I between the LEDs and ground. A control loop controls the semiconductor switch (T ) in a first LED cluster, referred to as the master cluster in the following text, such that a constant mean value of the LED current is achieved, wherein the master cluster has a predetermined number X of LEDs in its cluster, and with this control loop also driving at least the semiconductor switch (T ) in a further, LED cluster, referred to in the following text as the slave cluster.