KR20160149555A - Apparatus and method for driving light emitting diode - Google Patents

Abstract

According to an embodiment of the present invention, a light emitting diode driving device comprises: a control unit configured to detect the level of rectified power and generate a binary code corresponding to the level; a plurality of switches configured to correspond to each bit value of the binary code and configured to control on and off in accordance with the bit values; and a plurality of light emitting diodes configured to determine whether to emit light in accordance with on and off of the switches, thereby reducing the entire costs while reducing power factor distortion and total harmonic distortion.

Description

[0001] The present invention relates to a light emitting diode (LED)

The present invention relates to an apparatus and a method for driving a light emitting diode.

2. Description of the Related Art A light emitting diode (LED) is a semiconductor device formed in a p-n junction structure and emitting light by recombination of electrons and holes. In particular, LEDs are more efficient than conventional light emitting devices, have a long life span, and are environmentally friendly.

In general, an LED can be driven by applying a direct current (DC) power of a few volts in its structure. Therefore, in order to drive an LED by a commercial AC power source generally used in a home or a company, Is required. In order to drive the LEDs with commercial AC power, the LED driving devices usually include a rectifier circuit, an AC-DC converter, and the like.

However, since a general AC-DC converter is bulky and consumes a large amount of power, application of a general AC-DC converter to an LED driving device largely overcomes the advantages of LEDs such as high efficiency, small packaging size, and long life. Recently, many researches have been made on a device capable of driving an LED directly by an AC power source without an AC-DC converter.

In the case of LED lighting, the regulation of the power factor (PF) to increase the effective power and the regulation of the total harmonic distortion (THD) to prevent the interference to other power supply are getting worse. Therefore, there is a need for means to improve PF and THD performance in LEDs.

Published Patent Application No. 10-2011-0094315

An embodiment of the present invention provides an apparatus and method for driving a light emitting diode.

According to an embodiment of the present invention, there is provided an LED driving apparatus including: a controller for sensing a level of a rectified power supply and generating a binary code corresponding to a level; A plurality of switches corresponding to respective bit values of the binarization code and on / off controlled in accordance with bit values; And a plurality of light emitting diodes for determining whether or not to emit light according to on-off of the plurality of switches; . ≪ / RTI >

According to another aspect of the present invention, there is provided a method of driving a plurality of light emitting diodes that are connected in series to receive a rectified power, the method comprising: sensing a level of the rectified power; Generating a binary code; And controlling on-off of each of a plurality of switches corresponding one-to-one to the plurality of light emitting diodes based on each bit value of the binarization code; . ≪ / RTI >

The LED driving apparatus according to an embodiment of the present invention can reduce the power unit distortion and the total harmonic distortion while reducing the total unit price as well.

1 is a block diagram illustrating an LED driving apparatus according to an exemplary embodiment of the present invention.
2 is a circuit diagram illustrating the LED driving apparatus of FIG.
3 is a diagram illustrating a circuit for generating a binary code in the control unit of FIG.
4 is a flowchart illustrating a method of driving a light emitting diode according to an exemplary embodiment of the present invention.

The following detailed description of the invention refers to the accompanying drawings, which illustrate, by way of illustration, specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. It should be understood that the various embodiments of the present invention are different, but need not be mutually exclusive. For example, certain features, structures, and characteristics described herein may be implemented in other embodiments without departing from the spirit and scope of the invention in connection with an embodiment. It is also to be understood that the position or arrangement of the individual components within each disclosed embodiment may be varied without departing from the spirit and scope of the invention. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is to be limited only by the appended claims, along with the full scope of equivalents to which such claims are entitled. In the drawings, like reference numerals refer to the same or similar functions throughout the several views.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, so that those skilled in the art can easily carry out the present invention.

1 is a block diagram illustrating an LED driving apparatus according to an exemplary embodiment of the present invention.

Referring to FIG. 1, the LED driving apparatus 100 may include a controller 110, a plurality of switches 120, and a plurality of light emitting diodes 130.

The controller 110 may sense the level of the rectified power and generate a binary code corresponding to the level. That is, the controller 110 can generate a digital value by sensing an analog value. Here, the generated binarization code can be used for on / off control of the plurality of switches 120. [

The plurality of switches 120 correspond to the respective bit values of the binary code, and on / off can be controlled according to the bit values. For example, the on and off states of the plurality of switches 120 may correspond to bits 0 and 1, respectively.

For example, when the number of the plurality of switches 120 is three, the on-off of the first switch corresponds to 0 and 1 of the least significant bit (LSB) of the binary code, - off may correspond to 0 and 1 of the most significant bit (MSB) of the binarization code.

If the number of bits of the binarization code and the number of the plurality of switches 120 is three, the binarization code and the on-off combination of the plurality of switches 120 may correspond to eight values.

The plurality of light emitting diodes 130 may be lighted depending on the on / off state of the plurality of switches 120. That is, the plurality of light emitting diodes 130 may emit light of various intensities according to the on-off combination of the plurality of switches 120.

Accordingly, the total light emission intensity of the plurality of light emitting diodes 130 can be controlled by a relatively small number of the plurality of switches 120.

As the total emission intensity of the plurality of light emitting diodes 130 is finely controlled, the power factor distortion is reduced, the effective power can be increased, and the total harmonic distortion can be reduced, so that the interference to other power supply devices can be reduced.

The total light emission intensity of the plurality of light emitting diodes 130 can be finely controlled as the number of the plurality of switches 120 increases. As the number of the plurality of switches 120 increases, the number of elements and the number of pins of the integrated circuit increase, so that the overall unit price of the LED driving apparatus 100 can be increased.

Therefore, the power factor distortion and the total harmonic distortion in the plurality of light emitting diodes 130 may be trade-off with the overall unit price of the LED driving apparatus 100.

The light emitting diode driving apparatus 100 can control the total light emission intensity by using a relatively small number of switches. Therefore, the LED driving apparatus 100 can reduce the power unit distortion and the total harmonic distortion, as well as the overall unit price.

2 is a circuit diagram illustrating the LED driving apparatus of FIG.

2, the plurality of switches 120 are connected in parallel to a part of the plurality of light emitting diodes 130, and the plurality of light emitting diodes 130 are connected in series to receive rectified power . For example, the plurality of light emitting diodes 130 may correspond one-to-one with the plurality of switches 120. [

For example, an applied voltage of each of the plurality of light emitting diodes 130 may be expressed by the following Equation 1

Lt; / RTI > Here, Vk denotes an applied voltage of the k-th diode, and V1 denotes a reference voltage.

If the number of bits of the binarization code and the number of the plurality of switches 120 are three, the applied voltage ratio of each of the plurality of light emitting diodes 130 may be 1: 2: 4. Accordingly, 18 V is applied to the LED 1, 36 V is applied to the LED 2, and 72 V can be applied to the LED 3.

Referring to FIG. 2, the controller 110 controls the plurality of switches 120 to be turned on when the level of the rectified power is lower than the minimum reference voltage. When the level of the rectified power is higher than the maximum reference voltage, It is possible to control the switch 120 of the switch 120 to be turned off. Assuming that the minimum reference voltage is 0V and the maximum reference voltage is 126V, the on-off condition of the switch can be summarized as shown in Table 1 below.

Rectified voltage Q1 Q2 Q3 0V on on on 18V off on on 36V on off on 54V off off on 72V on on off 90V off on off 108V on off off 126V off off off

For example, the control unit 110 may include a sensing unit 111 for sensing the level of the rectified power. Here, the sensing unit 111 may output a voltage IC_REF corresponding to the level of the rectified power.

2, the light emitting diode driving apparatus 100 may include a rectifying unit 140 for rectifying the AC power and outputting the rectified power. For example, the rectifier 140 may be implemented as a bridge diode and rectify the AC power to a half-wave power source.

3 is a diagram illustrating a circuit for generating a binary code in the control unit of FIG.

Referring to FIG. 3, the controller 110 may include a binarization unit 112 for generating a binarization code corresponding to a voltage IC_REF corresponding to the level of the rectified power.

For example, the binarization unit 112 may be a micom that receives an AC power and outputs an output 1 (Out 1), an output 2 (Out 2), and an output 3 (Out 3). The resistor 1 (R1) connected to the set pin of the binarization unit 112 may be a pull-up resistor. An additional resistor (Rext) may be added to the resistor 1 and the set pin for setting. The voltage of the output 1 (Out1), the output 2 (Out2), and the output 3 (Out3) can be changed according to the resistance of the additional resistance (Rext).

The output 1 (Out1), the output 2 (Out2), and the output 3 (Out3) can be used as a gate drive voltage for controlling on / off of a plurality of switches.

Hereinafter, a method of driving a light emitting diode according to an embodiment of the present invention will be described. The same or corresponding contents to those of the light emitting diode driving apparatus described above with respect to the light emitting diode driving method will not be described redundantly.

4 is a flowchart illustrating a method of driving a light emitting diode according to an exemplary embodiment of the present invention.

The light emitting diode driving method includes the steps of: sensing a level of a rectified power source and generating a binary code corresponding to the level; (S10) controlling a plurality of switches corresponding to a plurality of light emitting diodes, Off based on each bit value of the binarization code (S20).

With the LED driving method, power factor distortion and total harmonic distortion generated in driving a plurality of light emitting diodes can be reduced, and the total unit price can also be reduced.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, Those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

100: Light emitting diode driving device
110:
120: a plurality of switches
130: Light emitting diode
140: rectification part

Claims (6)

A controller for detecting a level of the rectified power supply and generating a binary code corresponding to the level;
A plurality of switches corresponding to the respective bit values of the binarization code, the on / off being controlled in accordance with the bit values; And
A plurality of light emitting diodes for determining whether to emit light according to on-off of the plurality of switches; And a light emitting diode driving device.
The method according to claim 1,
Wherein the plurality of switches are connected in parallel with a part of the plurality of light emitting diodes,
Wherein the plurality of light emitting diodes are connected in series to each other to receive the rectified power.
3. The method of claim 2,
Wherein the plurality of light emitting diodes correspond one-to-one with the plurality of switches,
The voltage applied to each of the plurality of light emitting diodes is expressed by the following equation:

Lt; / RTI >
Here, Vk is an applied voltage of the k-th diode, and V1 is a reference voltage.
The method of claim 3,
The control unit controls the plurality of switches to be on when the level of the rectified power is lower than the minimum reference voltage and controls the plurality of switches to be off when the level of the rectified power is higher than the maximum reference voltage Emitting diodes.
The method according to claim 1,
And a rectifier for rectifying the AC power and outputting the rectified power.
A driving method of a plurality of light emitting diodes connected in series and supplied with rectified power,
Sensing a level of the rectified power and generating a binary code corresponding to the level; And
Controlling on / off of each of a plurality of switches corresponding one-to-one to the plurality of light emitting diodes based on each bit value of the binarization code; Emitting diode.

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