LIGHT EMITTING DIODE LAMP AND CONTROL CIRCUIT THEREOF

• US 20110121739A1
• Filed: 03/22/2010
• Published: 05/26/2011
• Est. Priority Date: 11/26/2009
• Status: Active Grant

• Current Assignee: Foxconn Technology Co., Ltd., Fuzhun Precision Industry Company Limited (Foxconn Technology Co., Ltd.)
• Original Assignee: Foxconn Technology Co., Ltd., Fuzhun Precision Industry Company Limited (Foxconn Technology Co., Ltd.)
• Inventors: KU, CHIN-LONG, ZHENG, HUAI-QING
• Granted Patent: US 8,314,574 B2
• Time in Patent Office: Days
• US Class Current: 315/158
• CPC Class Codes: H05B 45/12 using optical feedback
• CPC Class Codes: H05B 45/395 Linear regulators
• CPC Class Codes: Y02B 20/30 Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Abstract

A control circuit of an LED lamp includes a voltage regulator, at least a photo resistor and a feedback circuit. The voltage regulator includes an output terminal and a feedback terminal. The feedback circuit includes an amplifier having a first input end, a second input end and an output end. The LED lamp is connected between the first input end of the amplifier and the output terminal of the voltage regulator. The at least a photo resistor can sense a change of brightness level of an environment surrounding the LED lamp and a resistance of the at least a photo resistor increases along with a decrease of the brightness level. The change of resistance of the photo resistor is fed back to the voltage regulator via the amplifier, to thereby control an electric current flowing through the LED lamp.

Claims

1. A control circuit adapted for controlling an electric current through an LED of an LED lamp, comprising:

a voltage regulator comprising an output terminal for coupling to an input end of the LED thereby providing the electric current to the LED and a feedback terminal;

a feedback circuit comprising an amplifier, the amplifier comprising an in-phase input end, an out-phase input end and an output end, the out-phase input end being adapted for coupling to an output end of the LED, the output end of the amplifier being connected to the feedback terminal of the voltage regulator; and

at least a photo-resistor being connected between the in-phase input end of the amplifier and ground;

wherein the at least a photo-resistor senses a change of a brightness level of an environment surrounding the LED lamp and has a resistance thereof increasing along with a decrease of the brightness level of the environment surrounding the LED lamp, the increase of resistance of the at least a photo-resistor being fed back to the voltage regulator via the amplifier, to thereby control the electric current to the LED to be increased so that an intensity of light output of the LED is increased.

2. The LED lamp control circuit as described in claim 1, wherein the feedback circuit further comprises a resistor being connected between the in-phase input end and the output end of the amplifier.

3. The LED lamp control circuit as described in claim 2, further comprising another resistor being connected between the out-phase input end and the ground.

4. An LED lamp comprising:

a voltage regulator comprising an output terminal and a feedback terminal;

an amplifier comprising an in-phase input end, an out-phase input end and an output end, the output end of the amplifier being connected to the feedback terminal of the voltage regulator;

at least one LED being connected between the out-phase input end of the amplifier and the output terminal of the voltage regulator; and

at least a photo-resistor being connected between the in-phase input end of the amplifier and ground;

wherein the at least a photo-resistor senses a change of a brightness level of an environment surrounding the LED lamp and has a resistance thereof increasing along with a decrease of the brightness level of the environment surrounding the LED lamp, and the increase of resistance of the at least a photo-resistor is fed back to the voltage regulator via the amplifier, to thereby control an electric current flowing through the at least one LED to be increased to increase an intensity of light output of the at least one LED.

5. The LED lamp as described in claim 4, wherein the LED lamp further comprises a lamp seat, and the at least one LED is mounted on a side of the lamp seat, and the at least a photo-resistor mounted on another side of the lamp seat opposite to the at least one LED.

6. The LED lamp as described in claim 4, further comprising a resistor being connected between the in-phase input end and the output end of the amplifier.

7. The LED lamp as described in claim 6, further comprising another resistor being connected between the out-phase input end of the amplifier and the ground.