Patent ID: 7978743
Filing Date: 2011-07-12
Classification: H05B,Y02B

Abstract:
1. A driver circuit for a light emitting diode (LED), an organic light emitting diode (OLED), or light amplification by stimulated emission of radiation (LASER) diode device, the circuit comprising: a switching converter comprising at least one switching element, at least one reactive element and a switching output voltage, said switching converter being configured to generate said switching output voltage by sequential switching operations of said at least one switching element, a terminal for connecting said at LED, OLED or LASER diode device to switching output voltage, a linear current driver connected in series to said terminal, said linear current driver comprising an amplification element a current sensor and a current control input to control a drive current for said terminal, and a control unit comprising: a sensing input for sensing a current and/or voltage at said linear current driver, a switching control output for controlling said switching converter, a current control output for providing a current control signal to said linear current driver, and a programmable controller executing a control program for processing said sensing input and providing said switching control output and a said current control output in accordance with a set current value; wherein said set current value comprises one or more variable portions where the set current value changes over time, and one or more steady portions where the set current value remains substantially constant for providing a substantially constant output voltage value for said switching output voltage, and wherein said control program is configured to provide said switching control output voltage to increase said switching output voltage more than said substantially constant output voltage value before the variable portion.