LED drive circuit

An LED driver and circuit technology, applied in circuits, electrical components, semiconductor devices, etc., can solve the problems of difficulty in reducing chip size, circuit miniaturization and circuit cost reduction, etc., to eliminate the deviation of luminous amount, prevent through-current, The effect of improving the light-emitting duty cycle

Active Publication Date: 2012-08-15
CITIZEN WATCH CO LTD +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Furthermore, an analog switch requires at least 3 terminals, and it is difficult to reduce the chip size for an analog switch with high withstand vo

Method used

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  • LED drive circuit
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Examples

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Embodiment Construction

[0037] Hereinafter, the LED drive circuit will be described with reference to the drawings. However, the technical scope of the present invention is not limited to these embodiments, but relates to the inventions described in the claims and their equivalents.

[0038] figure 1 This is a schematic explanatory diagram of the LED drive circuit.

[0039] LED drive circuit 10 such as figure 1 As shown, it includes: a connection terminal 2 connected to a commercial power supply (AC 100V) 1, a diode bridge circuit 3 for full-wave rectification, a first LED block 4 including a plurality of LEDs, a second LED block 5 including a plurality of LEDs, a first A switch 6, a second switch 7, a reverse current preventing diode 8 for preventing through current, a control circuit 9, and the like.

[0040]The first LED block 4 and the second LED block 5 are formed by serially connecting 16 white LEDs of Vf=3.2V (power consumption 64mW, luminous flux 5lm). Therefore, when the applied voltag...

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PUM

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Abstract

Disclosed is an LED drive circuit, which is low cost, small, and capable of efficiently eliminating a through current between a plurality of LED groups. The LED drive circuit has: a rectifier; a first LED group that includes a plurality of LEDs; a second LED group that includes a plurality of LEDs; a connecting unit, which connects the first and the second LED groups to the rectifier in series, or connects the first and the second LED groups to the rectifier in parallel; a control unit, which controls the connecting unit, and switches the connection of the first and the second LED groups to the rectifier from the parallel connection to the series connection; and a diode, which is disposed between the first LED group and the second LED group, and which eliminates the reverse direction current.

Description

technical field [0001] The present invention relates to an LED drive circuit, and more particularly to an LED drive circuit for efficient LED light emission using an AC power source. Background technique [0002] There is known a light-emitting LED drive circuit for lighting that applies a rectified voltage output from a bridge diode that performs full-wave rectification of AC power supplied from a commercial power supply to a plurality of LEDs connected in series to emit light. (For example, refer to Patent Document 1). [0003] In an LED, when a voltage equal to or higher than a forward drop voltage (Vf) is applied to the LED, light emission with a luminosity substantially proportional to a forward current (If) is performed. Therefore, when n LEDs are connected in series, the LEDs emit light when a voltage equal to or greater than n×Vf is applied to the LEDs. In addition, the rectified voltage output from the bridge diode that performs full-wave rectification of the AC c...

Claims

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Application Information

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IPC IPC(8): H01L33/00
CPCH05B45/44
Inventor 秋山贵
Owner CITIZEN WATCH CO LTD
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