LED DRIVING CIRCUIT

• US 20110140622A1
• Filed: 11/19/2010
• Published: 06/16/2011
• Est. Priority Date: 12/14/2009
• Status: Active Grant

• Current Assignee: Minebea Mitsumi, Inc.
• Original Assignee: Minebea Company Limited (MinebeaMitsumi Inc.)
• Inventors: SUZUKI, Shinichi
• Granted Patent: US 8,816,597 B2
• Time in Patent Office: Days
• US Class Current: 315/224
• CPC Class Codes: H05B 45/3575 by means of dummy loads or bleeder circuits, e.g. for dimmers
• CPC Class Codes: H05B 45/3725 Switched mode power supply [SMPS]
• CPC Class Codes: Y02B 20/30 Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Abstract

An LED driving circuit includes a dimming circuit that controls a conducting angle of an alternating current supplied from a power supply to phase-control a current to be supplied to an LED, a rectifier circuit that rectifies an alternating-current voltage output from the dimming circuit, a smoothing circuit that smoothes a direct current voltage output from the rectifier circuit, a switching device that is connected with the LED in series; a constant current control circuit that outputs a high frequency pulse signal to the switching device to control the switching device, and a bleeder circuit that is provided between an output terminal of the rectifier circuit and a ground and that has a bleeder resistance and a bleeder switch connected in series. The high frequency pulse signal is input to the bleeder switch so that a bleeder current having a high frequency pulse form flows in the bleeder resistance.

Claims

1. An LED driving circuit for driving an LED, the circuit comprising:

a dimming circuit that controls a conducting angle of an alternating current supplied from a commercial alternating-current power supply so as to phase-control a current to be supplied to the LED;

a rectifier circuit that rectifies an alternating-current voltage output from the dimming circuit;

a smoothing circuit that smoothes a direct current voltage output from the rectifier circuit;

a switching device that is connected with the LED in series;

a constant current control circuit that outputs a high frequency pulse signal to the switching device to control an ON/OFF operation of the switching device so that a current flowing in the LED becomes constant; and

a bleeder circuit that is provided between an output terminal of the rectifier circuit and a ground and that has a bleeder resistance and a bleeder switch which are connected with each other in series,

wherein the high frequency pulse signal is input to the bleeder switch so that a bleeder current having a high frequency pulse form flows in the bleeder resistance.

2. An LED driving circuit for driving an LED, the circuit comprising:

a dimming circuit that controls a conducting angle of an alternating current supplied from a commercial alternating-current power supply so as to phase-control a current to be supplied to the LED;

a rectifier circuit that rectifies an alternating-current voltage output from the dimming circuit;

a smoothing circuit that smoothes a direct current voltage output from the rectifier circuit;

a switching device that is connected with the LED in series;

a constant current control circuit that outputs a high frequency pulse signal to the switching device to control an ON/OFF operation of the switching device so that current flowing in the LED becomes constant; and

a bleeder circuit that is provided between an output terminal of the rectifier circuit and a ground and that has a bleeder resistance and a bleeder switch which are connected with each other in series,

wherein a high frequency pulse signal output from an oscillation circuit is input to the bleeder switch so that a bleeder current having a high frequency pulse form flows in the bleeder resistance.