LED lighting device and dimming control method therefor

Patent metadata

Field	Value
Publication number	US-10834794-B2
Application number	US-201816630678-A
Country	US
Kind code	B2
Filing date	Jul 12, 2018
Priority date	Jul 21, 2017
Publication date	Nov 10, 2020
Grant date	Nov 10, 2020

Abstract

An LED lighting device according to one embodiment of the present invention comprises: an LED array; a first control unit for controlling the dimming of the LED array; a second control unit for transmitting, to the first control unit, a dimming control signal for controlling the dimming of the LED array; and a transformer comprising a primary coil and a secondary coil spaced apart from each other, wherein the first control unit is connected to the primary coil, the second control unit is connected to the secondary coil, the primary coil and the secondary coil are insulated from each other, the transformer transmits a pulse signal that repeats on/off at predetermined intervals from the first control unit to the second control unit, and, when the pulse signal transmitted from the first control unit to the second control unit via the transformer becomes off, the dimming control signal is transmitted from the second control unit to the first control unit via the transformer and is used to control the dimming of the LED array.

First claim

The invention claimed is:

1. A light emitting diode (LED) lighting device comprising:
an LED array;
a first control unit configured to control dimming of the LED array;
a second control unit configured to transmit a dimming control signal, which controls the dimming of the LED array, to the first control unit; and
a transformer including a primary coil and a secondary coil spaced apart from each other,
wherein the first control unit is connected to the primary coil and the second control unit is connected to the secondary coil,
the primary coil and the secondary coil are isolated from each other,
the transformer transmits a pulse signal, which is repeatedly turned on and turned off at a predetermined interval, from the first control unit to the second control unit,
the dimming control signal is transmitted from the second control unit to the first control unit through the transformer when the pulse signal transmitted from the first control unit to the second control unit through the transformer is turned off, and
the first control unit rectifies the dimming control signal which is an alternating current signal transmitted from the second control unit to the first control unit through the transformer to a direct current signal and then controls the dimming of the LED array using a value in which an offset voltage is cancelled, wherein:
the first control unit includes a rectifier, which includes a diode configured to rectify the dimming control signal and a capacitor connected between the diode and a direct current power source, and an offset voltage cancellation part configured to cancel the offset voltage from a signal output from the rectifier; and
the offset voltage includes a voltage value of the direct current power source.

2. The LED lighting device of claim 1 , wherein the offset voltage cancellation part cancels the offset voltage using voltage distribution.

3. The LED lighting device of claim 2 , wherein the offset voltage cancellation part includes a plurality of resistors connected in series between the rectifier and the LED array, and a Zener diode or a shunt regulator connected to one of the plurality of resistors in parallel.

4. The LED lighting device of claim 1 , wherein the dimming control signal is a signal in which a predetermined correction voltage is added to a voltage output from a dimmer.

5. The LED lighting device of claim 4 , wherein a correction voltage is generated by the plurality of resistors connected in series to a dimmer and the Zener diode or shunt regulator connected to one of the plurality of resistors in parallel.

6. The LED lighting device of claim 5 , wherein the offset voltage further includes the correction voltage.

7. The LED lighting device of claim 1 , wherein a turn ratio between the primary coil and the secondary coil of the transformer is 1 to 1 and the transformer operates in a flyback manner.

8. The LED lighting device of claim 1 , wherein the pulse signal is a signal having a predetermined duty ratio with respect to a voltage value of direct current power input to the first control unit.

9. The LED lighting device of claim 1 , wherein the dimming control signal has a value set by a user or a value automatically set according to ambient light.

10. The LED lighting device of claim 9 , wherein a MCU (main control unit) is further disposed between the first control unit and the LED array.

11. The LED lighting device of claim 1 , wherein one end of the diode is connected to a first node of the first control unit on which the dimming control signal is reflected, one end of the capacitor is connected to the direct current power, and the other end of the diode is connected to the other end of the capacitor.

12. The LED lighting device of claim 1 , wherein the first control unit further includes a pulse generator to generate the pulse signal.

13. The LED lighting device of claim 12 , wherein the pulse generator includes a transistor, a pulse signal is applied to a gate electrode of the transistor, and a drain electrode of the transistor is connected to the primary coil.

14. The LED lighting device of claim 4 , wherein the correction voltage is added by voltage distribution.

15. The LED lighting device of claim 4 , wherein the second control unit receives the dimming control signal from the dimmer through a DIM+ line and a DIM− line, and a Zener diode is connected between the DIM+ line and the DIM− line.

16. The LED lighting device of claim 5 , wherein a level of the correction voltage is controlled according to a resistance ratio between the plurality of resistors.

17. A dimming control method of a light emitting diode (LED) lighting device, comprising:
generating a pulse signal, which is repeatedly turned on and turned off at a predetermined interval, in a first control unit including an LED array;
transmitting the pulse signal generated in the first control unit to a second control unit including a dimmer through a transformer;
transmitting, by the second control unit, a dimming control signal which controls the LED array to the first control unit through the transformer when the pulse signal of the first control unit transmitted through the transformer is turned off;
rectifying, by the first control unit, the dimming control signal, which is an alternating current signal transmitted through the transformer, to a direct current signal;
cancelling, by the first control unit, an offset voltage from the rectified signal; and
controlling, by the first control unit, dimming of the LED array using a signal from which the offset voltage is cancelled, wherein:
the dimming control signal is rectified using a diode and then a voltage of a direct current power source is added in the rectified direct current signal; and
the voltage of the direct current power source is cancelled in the cancelling of the offset voltage.

18. The dimming control method of claim 17 , wherein a voltage of the signal from which the offset voltage is cancelled is the same as a voltage output from the dimmer.

Assignees

• Lg Innotek Co Ltd

Inventors

• Jo Ji Woong
• Lee Jong Hyun
• Choi Jae Ho
• Kim Min Hak
• Seo Min Su
• Baek Seung Wan

Classifications

• H10D8/25

  Zener diodes · CPC title

• H05B45/392 Primary

  wherein the LEDs are placed as freewheeling diodes at the secondary side of an isolation transformer · CPC title

• H05B45/385 Primary

  using flyback topology · CPC title

• H05B45/10

  Controlling the intensity of the light · CPC title

• H05B45/00

  Circuit arrangements for operating light-emitting diodes [LED] · CPC title