LED DRIVING CIRCUIT

• US 20120256550A1
• Filed: 11/24/2010
• Published: 10/11/2012
• Est. Priority Date: 12/22/2009
• Status: Abandoned Application

• Current Assignee: Citizen Electronics Company Limited, Citizen Holdings Co., Ltd. (Citizen Electronics Company Limited)
• Original Assignee: Citizen Electronics Company Limited, Citizen Holdings Co., Ltd. (Citizen Electronics Company Limited)
• Inventors: Akiyama, Takashi
• Application Number:
  US13/518,268
• Publication Number:
  US 20120256550A1
• Time in Patent Office: Days
• US Class Current: 315/187
• CPC Class Codes: H05B 45/44 with an active control inside an LED matrix

Abstract

The present invention is directed to providing an LED driving circuit that can be reduced in size and produced at low cost, and that can effectively prevent a shoot-through current that may flow between a plurality of LED arrays. The LED driving circuit includes a rectifier, a first LED array containing a plurality of LEDs, a second LED array containing a plurality of LEDs; a connection unit for connecting the first and second LED arrays in series relative to the rectifier or for connecting the first and second LED arrays in parallel relative to the rectifier, a control unit for switching the connection of the first and second LED arrays relative to the rectifier from parallel to series by controlling the connection unit, and a reverse current preventing diode disposed between the first LED array and the second LED array.

Claims

1. An LED driving circuit comprising:

a rectifier;

a first LED array containing a plurality of LEDs;

a second LED array containing a plurality of LEDs;

a connection unit for connecting said first and second LED arrays in series relative to said rectifier or for connecting said first and second LED arrays in parallel relative to said rectifier;

a control unit for switching the connection of said first and second LED arrays relative to said rectifier from parallel to series by controlling said connection unit; and

a reverse current preventing diode disposed between said first LED array and said second LED array.

2. The LED driving circuit according to claim 1, further comprising a constant-current circuit which is disposed between said rectifier and said first and second LED arrays.

3. The LED driving circuit according to claim 1 or 2, wherein said control unit performs switching control in accordance with an output voltage of said rectifier.

4. The LED driving circuit according to claim 1 or 2, wherein said control unit performs switching control in accordance with a current that flows through said first LED array or said second LED array.

5. The LED driving circuit according to any one of claims 1 to 4, wherein a capacitor is connected to an output end of said rectifier via a diode and a resistor or constant-current diode, and wherein said diode is disposed in a charge path of said capacitor and said resistor or constant-current diode is disposed in a discharge path of said capacitor.