KR100859034B1 - Circuit for operating led in backlighting inverter - Google Patents

Circuit for operating led in backlighting inverter Download PDF

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Publication number
KR100859034B1
KR100859034B1 KR1020070045833A KR20070045833A KR100859034B1 KR 100859034 B1 KR100859034 B1 KR 100859034B1 KR 1020070045833 A KR1020070045833 A KR 1020070045833A KR 20070045833 A KR20070045833 A KR 20070045833A KR 100859034 B1 KR100859034 B1 KR 100859034B1
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South Korea
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led
resistor
input
driving circuit
sensing
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KR1020070045833A
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Korean (ko)
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한재현
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엘지이노텍 주식회사
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    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
    • G09G3/3406—Control of illumination source
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
    • G09G3/3406—Control of illumination source
    • G09G3/3413—Details of control of colour illumination sources
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/1336—Illuminating devices
    • G02F1/133602—Direct backlight
    • G02F1/133612—Electrical details
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
    • Y02B20/30—Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Computer Hardware Design (AREA)
  • General Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • Led Devices (AREA)

Abstract

An LED(Light Emitting Diode) driving circuit in a backlighting inverter is provided to reduce variation of output voltage in an over voltage state of the circuit caused by sudden increase of input voltage, thereby achieving stable output. An LED driver(100) receives input voltage and outputs a signal for driving an LED(1,2). A sensing resistance(Rs) senses currents flowing within the LED. A sensing resistance value changing unit(200) includes a first resistance and a switching unit(210), and reduces a sensing resistance value when input voltage is suddenly changed. The first resistance is connected with the sensing resistance in parallel. The switching unit enables or disables the first resistance. A comparing unit(300) outputs a control signal for controlling an operation of the LED driver according to voltage sensed by the sensing resistance.

Description

백라이팅 인버터에서의 ＬＥＤ 구동회로 {Circuit for operating LED in backlighting inverter}LED driving circuit for backlighting inverter {Circuit for operating LED in backlighting inverter}

도 1은 일반적인 LED를 직렬로 연결한 모습이다.1 shows a typical LED connected in series.

도 2는 종래 백라이팅 인버터에서의 LED 구동회로의 회로도이다.2 is a circuit diagram of an LED driving circuit in a conventional backlighting inverter.

도 3은 종래 백라이팅 인버터에서의 LED 구동회로의 입출력 신호 파형을 보여주는 도면이다.3 is a view showing input and output signal waveforms of the LED driving circuit in the conventional backlighting inverter.

도 4는 본 발명의 일 실시예에 따른 백라이팅 인버터에서의 LED 구동회로의 회로도이다.4 is a circuit diagram of the LED driving circuit in the backlighting inverter according to an embodiment of the present invention.

도 5는 본 발명의 일 실시예에 따른 백라이팅 인버터에서의 LED 구동회로의 입출력 신호 파형을 보여주는 도면이다.5 is a view showing input and output signal waveforms of the LED driving circuit in the backlighting inverter according to an embodiment of the present invention.

*도면의 주요 부분에 대한 부호의 설명** Description of the symbols for the main parts of the drawings *

100 LED 구동부 200 감지저항값 변경수단100 LED driver 200 Detection resistance change means

300 비교부 Rs 감지저항300 Rs sense resistor

본 발명은 백라이팅 인버터에서의 LED 구동회로에 관한 것이다. The present invention relates to an LED drive circuit in a backlighting inverter.

일반적으로 액정표시장치(Liquid Crystal Display, 이하 "LCD"라 함)는 경량, 박형, 저소비 전력구동 등의 특징으로 인해 그 응용범위가 점차 넓어지고 있는 추세에 있다. 이러한 추세에 따라, LCD는 사무자동화 기기, 오디오/비디오 기기 등에 이용되고 있다. 한편, LCD는 매트릭스 형태로 배열되어진 다수의 제어용 스위치들에 인가되는 영상신호에 따라 광빔의 투과량이 조절되어 화면에 원하는 화상을 표시하게 된다. 이와 같은 LCD는 자발광 표시장치가 아니기 때문에 백라이팅(Backlighting) 인버터가 사용된다. In general, liquid crystal displays (hereinafter, referred to as "LCDs") have tended to be increasingly wider in application due to features such as light weight, thinness, and low power consumption. According to this trend, LCDs are used for office automation equipment, audio / video equipment, and the like. On the other hand, the LCD is controlled to display the desired image on the screen by adjusting the transmission amount of the light beam according to the image signal applied to the plurality of control switches arranged in a matrix form. Since such LCDs are not self-luminescent displays, backlighting inverters are used.

최근 고색재현과 오랜 수명, 그리고 무수은이라는 장점 때문에 LED(Light Emitting Diode)가 LCD의 백라이트 광원으로 많이 사용되고 있다. 그리고, 이러한 LED를 구동하기 위한 다양한 LED 구동회로가 개발되고 있는 실정이다.Recently, LED (Light Emitting Diode) is widely used as backlight source of LCD because of high color reproduction, long life, and mercury-free merits. In addition, various LED driving circuits for driving such LEDs have been developed.

도 1은 일반적인 LED를 직렬로 연결한 모습이다. 도 1에서 보는 바와 같이, 적색(Red), 녹색(Green), 청색(Blue) LED를 각각 직렬로 연결하여 필요한 휘도를 출력하게 된다. 1 shows a typical LED connected in series. As shown in FIG. 1, red, green, and blue LEDs are connected in series to output necessary luminance.

도 2는 종래 백라이팅 인버터에서의 LED 구동회로의 회로도이다. 도 2는 부스트 컨버터 회로로서, 입력전압보다 출력전압이 높을 때 사용하는 회로이다. 2 is a circuit diagram of an LED driving circuit in a conventional backlighting inverter. 2 is a boost converter circuit, which is used when the output voltage is higher than the input voltage.

도 2에서 스위치(Q2)가 온(On) 되어 있는 동안에는 입력전원(Vin)이 인덕터(L1) 양단에 걸리게 되므로, 인덕터(L1)에 전류가 충전된다. 그리고, 스위치(Q2)가 오프(Off) 되면, 인덕터(L1)에 충전된 전류가 부하측인 LED(1, 2)쪽에 전달되는 원리로 구동된다. In FIG. 2, since the input power source Vin is applied across the inductor L1 while the switch Q2 is on, current is charged in the inductor L1. When the switch Q2 is turned off, the current charged in the inductor L1 is driven to the LEDs 1 and 2 on the load side.

도 2에서 감지저항(Rs)은 LED(1, 2)에 흐르는 전류를 감지하기 위해 사용되며, OP 앰프(OP1)의 비반전단자에는 감지저항(Rs)에 걸리는 전압(Vcomp)이 입력되고, 반전단자에는 기준전압(Vref)이 입력되며, OP 앰프(OP1)는 양 전압을 비교하여 스위치(Q2)의 온/오프 듀티(duty)를 조절하는 신호를 출력하게 된다. In FIG. 2, the sensing resistor Rs is used to sense current flowing through the LEDs 1 and 2, and the voltage Vcomp applied to the sensing resistor Rs is input to the non-inverting terminal of the OP amplifier OP1. The reference voltage Vref is input to the inverting terminal, and the OP amplifier OP1 compares both voltages and outputs a signal for adjusting the on / off duty of the switch Q2.

종래에는 이와 같은 방식으로 스위치(Q2)의 듀티 타임을 조절하여 LED(1, 2)를 구동하였다. 그러나, 종래에는 입력전압(Vin)의 갑작스런 전압 상승이 발생할 경우에 LED(1, 2)에 흘러갈 출력신호에도 영향을 미치는 문제점이 있다. 예를 들어, 노트북의 경우에 배터리모드로 사용하다가 어댑터를 연결하면 갑자기 입력전압이 상승하게 된다. 이를 LED 구동회로의 입출력 파형을 참조하여 설명하면 다음과 같다.Conventionally, the duty time of the switch Q2 is adjusted in this manner to drive the LEDs 1 and 2. However, in the related art, there is a problem that also affects an output signal flowing to the LEDs 1 and 2 when a sudden voltage rise of the input voltage Vin occurs. For example, in the case of a notebook, when the battery mode is used and the adapter is connected, the input voltage suddenly rises. This will be described with reference to the input / output waveform of the LED driving circuit as follows.

도 3은 종래 백라이팅 인버터에서의 LED 구동회로의 입출력 신호 파형을 보여주는 도면이다. 도 3에서 입력전압(Vin)이 갑자기 상승하는 구간에서 출력전압(Vout)도 갑자기 상승하게 되고, 출력전압(Vout)은 일정시간동안 LED(1, 2)의 포워드 전압(Forward Voltage)보다 높아지게 된다. 이러한 현상은 LED(1, 2)의 수명을 단축시킬 수 있으며, 심지어는 LED(1, 2)의 파괴까지 발생할 수 있는 문제점이 있다. 3 is a view showing input and output signal waveforms of the LED driving circuit in the conventional backlighting inverter. In FIG. 3, the output voltage Vout suddenly rises while the input voltage Vin suddenly rises, and the output voltage Vout becomes higher than the forward voltage of the LEDs 1 and 2 for a predetermined time. . This phenomenon can shorten the life of the LED (1, 2), there is a problem that can occur even destruction of the LED (1, 2).

본 발명은 회로의 과전압 상태에서 안정적인 출력이 가능하도록 하는 백라이팅 인버터에서의 LED 구동 회로를 제공한다.The present invention provides an LED drive circuit in a backlighting inverter that enables stable output in an overvoltage condition of the circuit.

본 발명은 입력전압을 입력받아 LED를 구동시키기 위한 신호를 출력하는 LED 구동부, 상기 LED에 흐르는 전류를 감지하기 위한 감지저항, 입력전압이 급격히 변할 때 감지저항값을 낮추기 위한 감지저항값 변경수단, 상기 감지저항에 의해 감지되는 전압에 따라 상기 LED 구동부의 동작을 제어하는 제어신호를 출력하는 비교부를 포함한다. The present invention is a LED driving unit for receiving an input voltage and outputting a signal for driving the LED, a sensing resistor for sensing the current flowing through the LED, a sensing resistance value changing means for lowering the sensing resistance value when the input voltage changes rapidly; And a comparator for outputting a control signal for controlling the operation of the LED driver according to the voltage sensed by the sensing resistor.

이하, 첨부된 도면을 참조해서 본 발명의 실시예를 상세히 설명하면 다음과 같다. 우선 각 도면의 구성 요소들에 참조 부호를 부가함에 있어서, 동일한 구성 요소들에 한해서는 비록 다른 도면상에 표시되더라도 가능한 한 동일한 부호를 가지도록 하고 있음에 유의해야 한다. 그리고, 본 발명을 설명함에 있어서, 관련된 공지 기능 혹은 구성에 대한 구체적인 설명이 본 발명의 요지를 불필요하게 흐릴 수 있다고 판단되는 경우 그 상세한 설명을 생략한다.Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. First of all, in adding reference numerals to the components of each drawing, it should be noted that the same reference numerals have the same reference numerals as much as possible even if displayed on different drawings. In describing the present invention, when it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

도 4는 본 발명의 일 실시예에 따른 백라이팅 인버터에서의 LED 구동회로의 회로도이다. LED 구동 회로는 LED 구동부(100), 감지저항(Rs), 감지저항값 변경수단(200), 비교부(300)를 포함한다.4 is a circuit diagram of the LED driving circuit in the backlighting inverter according to an embodiment of the present invention. The LED driving circuit includes an LED driving unit 100, a sensing resistor Rs, a sensing resistance value changing unit 200, and a comparing unit 300.

LED 구동부(100)는 입력전압(Vin)을 입력받아 LED(1, 2)를 구동시키기 위한 신호를 출력한다. The LED driver 100 receives an input voltage Vin and outputs a signal for driving the LEDs 1 and 2.

감지저항(Rs)은 LED(1, 2)에 흐르는 전류를 감지하는 역할을 한다. The sensing resistor Rs serves to sense the current flowing in the LEDs 1 and 2.

감지저항값 변경수단(200)은 입력전압(Vin)이 급격히 변할 때 감지저항값을 낮추는 역할을 한다.The detection resistance value changing unit 200 serves to lower the detection resistance value when the input voltage Vin changes abruptly.

비교부(300)는 감지저항(Rs)에 의해 감지되는 전압에 따라 LED 구동부(100)의 동작을 제어하는 제어신호를 출력한다.The comparator 300 outputs a control signal for controlling the operation of the LED driver 100 according to the voltage sensed by the sensing resistor Rs.

도 4에서 감지저항값 변경수단(200)은 감지저항(Rs)과 병렬로 연결된 제1저항(R1)과, 제1저항(R1)을 인에이블(enable)시키거나 디스에이블(disable)시키는 스위칭부(210)를 포함한다. In FIG. 4, the sensing resistance value changing unit 200 switches the first resistor R1 connected in parallel with the sensing resistor Rs and the first resistor R1 to enable or disable the first resistor R1. The unit 210 is included.

스위칭부(210)는 베이스에 입력전압(Vin)이 입력되고, 컬렉터는 제1저항(R1)에 연결되고, 에미터는 접지에 연결되는 트랜지스터(Q1)로 구성된다.The switching unit 210 includes an input voltage Vin input to the base, a collector connected to the first resistor R1, and an emitter composed of a transistor Q1 connected to ground.

제1커패시터(C1)는 트랜지스터(Q1)의 베이스에 연결되어 있다. The first capacitor C1 is connected to the base of the transistor Q1.

제2커패시터(C2)는 일측은 제1커패시터(C1)와 베이스 사이에 연결되고, 타측은 접지에 연결되어 있다. One side of the second capacitor C2 is connected between the first capacitor C1 and the base, and the other side thereof is connected to the ground.

제2저항(R2)은 일측은 제1커패시터(C1)와 베이스 사이에 연결되고, 타측은 접지에 연결되어 있다. One side of the second resistor R2 is connected between the first capacitor C1 and the base, and the other side thereof is connected to the ground.

도 4에서 비교부(300)는 비반전단자에 기준전압(Vref)이 입력되고, 반전단자는 감지저항(Rs)과 감지저항값 변경수단(200) 사이에 연결되며, 출력단자에서 LED 구동부(100)의 동작을 제어하는 제어신호가 출력되는 OP 앰프(OP1)로 구성되어 있다.In FIG. 4, the comparator 300 has a reference voltage Vref input to the non-inverting terminal, and an inverting terminal is connected between the sensing resistor Rs and the sensing resistance value changing means 200, and the LED driving unit at the output terminal. OP amplifier OP1 to which a control signal for controlling the operation of 100 is output.

도 4의 실시예에서 OP 앰프(OP1)는 비반전단자에 램프파형의 기준전압(Vref)이 입력되고, 출력단자에서 소정 듀티를 갖는 구형파 형태의 제어신호가 출력된다.In the embodiment of FIG. 4, the OP amplifier OP1 receives a ramp waveform reference voltage Vref at a non-inverting terminal, and outputs a control signal in the form of a square wave having a predetermined duty at an output terminal.

도 4에서 LED 구동부(100)는 일측에 입력전압이 입력되는 인덕터(L1)와, 게 이트에 제어신호가 입력되고, 드레인이 인덕터(L1)의 타측과 LED(1, 2)의 애노드 사이에 연결되고, 소스가 접지에 연결되는 MOSFET(Q2)와, 일측이 인덕터(L1)의 타측과 LED(1, 2)의 애노드 사이에 연결되고, 타측이 접지에 연결되는 제3커패시터(C3), 애노드가 인덕터의 타측에 연결되고, 캐소드가 LED(1, 2)의 애노드와 연결되는 다이오드(D1)를 포함하여 이루어진다. LED 구동부(100)에서는 LED(1, 2)를 구동시키기 위한 구동신호(Vout)가 출력된다. In FIG. 4, the LED driver 100 has an inductor L1 having an input voltage input to one side thereof, a control signal input to a gate, and a drain thereof between the other side of the inductor L1 and the anode of the LEDs 1 and 2. A third capacitor C3 connected to the MOSFET Q2 having a source connected to ground, one side connected between the other side of the inductor L1 and the anode of the LEDs 1 and 2, and the other side connected to the ground; The anode comprises a diode D1 connected to the other side of the inductor and the cathode connected to the anode of the LEDs 1, 2. The LED driver 100 outputs a driving signal Vout for driving the LEDs 1 and 2.

도 4에서 OP 앰프(OP1)의 반전단자에 입력되는 전압은 감지저항(Rs)과 감지저항값 변경수단(200)에 의해 조절된다. In FIG. 4, the voltage input to the inverting terminal of the OP amplifier OP1 is controlled by the sensing resistor Rs and the sensing resistor value changing means 200.

즉, 본 발명에서 평상시에는 감지저항값 변경수단(200)의 트랜지스터(Q1)가 오프된 상태이기 때문에 제1저항(R1)에 전류가 흐르지 않는다. 따라서, OP 앰프(OP1)의 반전단자에는 감지저항(Rs)에 걸리는 전압이 입력된다. That is, in the present invention, since the transistor Q1 of the detection resistance value changing means 200 is turned off normally, no current flows in the first resistor R1. Therefore, the voltage applied to the sensing resistor Rs is input to the inverting terminal of the OP amplifier OP1.

그러나, 입력전압(Vin)이 갑자기 상승하면 입력전압(Vin)의 상승값이 감지저항값 변경수단(200)의 트랜지스터(Q1)의 베이스에 입력되어 트랜지스터(Q1)를 턴 온시키게 된다. 이렇게 되면, 제1저항(R1)이 인에이블되기 때문에 OP 앰프(OP1)의 반전단자에는 감지저항(Rs)과 감지저항값 변경수단(200)의 합성 임피던스에 따른 전압이 입력된다. 이에 따라 OP 앰프(OP1)에서는 소정 듀티를 갖는 신호를 출력하고, 이 신호가 LED 구동부(100)의 MOSFET(Q2)의 구동을 제어하게 된다. 이는 입력전압(Vin)의 갑작스런 변동에 따른 출력전압(Vout)의 상승을 억제하는 결과를 가져온다. 이렇게 됨으로써, 본 발명에서는 LED(1, 2)의 포워드 전압(Forword voltage) 이상의 전압이 걸리는 것을 미연에 방지하게 된다. 본 발명에서의 입력 신호와 출 력신호의 파형을 보여주는 도면이 도 5에 도시되어 있다. However, if the input voltage Vin suddenly rises, the rising value of the input voltage Vin is input to the base of the transistor Q1 of the sensing resistance value changing means 200 to turn on the transistor Q1. In this case, since the first resistor R1 is enabled, the voltage corresponding to the combined impedance of the sensing resistor Rs and the sensing resistance value changing unit 200 is input to the inverting terminal of the OP amplifier OP1. Accordingly, the OP amplifier OP1 outputs a signal having a predetermined duty, and this signal controls the driving of the MOSFET Q2 of the LED driver 100. This results in suppressing an increase in the output voltage Vout due to a sudden change in the input voltage Vin. By doing so, in the present invention, it is possible to prevent the voltage above the forward voltage of the LEDs 1 and 2 from being applied. 5 is a view illustrating waveforms of an input signal and an output signal in the present invention.

도 5는 본 발명의 일 실시예에 따른 백라이팅 인버터에서의 LED 구동회로의 입출력 신호 파형을 보여주는 도면이다. 도 5에서 보는 바와 같이, 입력전압(Vin)이 급격하게 상승하는 구간에서 출력전압(Vout)의 파형은 거의 변동이 없는 것을 A구간을 통해서 확인할 수 있다. 5 is a view showing input and output signal waveforms of the LED driving circuit in the backlighting inverter according to an embodiment of the present invention. As shown in FIG. 5, it can be confirmed through the section A that the waveform of the output voltage Vout is almost unchanged in the section in which the input voltage Vin rises rapidly.

이상 본 발명을 몇 가지 바람직한 실시예를 사용하여 설명하였으나, 이들 실시예는 예시적인 것이며 한정적인 것이 아니다. 본 발명이 속하는 기술분야에서 통상의 지식을 지닌 자라면 본 발명의 사상과 첨부된 특허청구범위에 제시된 권리범위에서 벗어나지 않으면서 다양한 변화와 수정을 가할 수 있음을 이해할 것이다.While the invention has been described using some preferred embodiments, these embodiments are illustrative and not restrictive. Those skilled in the art will appreciate that various changes and modifications can be made without departing from the spirit of the invention and the scope of the rights set forth in the appended claims.

이상에서 설명한 바와 같이, 본 발명에 의하면 백라이팅 인버터에서의 LED 구동회로에서 입력전압의 급격한 상승으로 인한 회로의 과전압 상태에서 출력전압의 변동을 감소시켜서 안정적인 출력이 가능하도록 하는 효과가 있다. As described above, according to the present invention, the LED driving circuit in the backlighting inverter has an effect of reducing the variation of the output voltage in the overvoltage state of the circuit due to the sudden increase in the input voltage, thereby enabling a stable output.

Claims (9)

입력전압을 입력받아 LED를 구동시키기 위한 신호를 출력하는 LED 구동부;An LED driver which receives an input voltage and outputs a signal for driving the LED; 상기 LED에 흐르는 전류를 감지하기 위한 감지저항;A sensing resistor for sensing a current flowing in the LED; 상기 감지저항과 병렬로 연결된 제1저항과, 상기 제1저항을 인에이블시키거나 디스에이블시키는 스위칭부를 포함하고, 입력전압이 급격히 변할 때 감지저항값을 낮추기 위한 감지저항값 변경수단;Sensing resistor value changing means for lowering the sense resistor value when the input voltage changes abruptly, including a first resistor connected in parallel with the sense resistor and a switching unit for enabling or disabling the first resistor; 상기 감지저항에 의해 감지되는 전압에 따라 상기 LED 구동부의 동작을 제어하는 제어신호를 출력하는 비교부A comparator for outputting a control signal for controlling the operation of the LED driver in accordance with the voltage sensed by the sense resistor 를 포함하는 백라이팅 인버터에서의 LED 구동회로.LED driving circuit in the backlighting inverter comprising a. 삭제delete 제1항에 있어서,The method of claim 1, 상기 스위칭부는 베이스에 입력전압이 입력되고, 컬렉터는 상기 제1저항에 연결되고, 에미터는 접지에 연결되는 트랜지스터로 구성되는 백라이팅 인버터에서의 LED 구동회로.The switching unit is a LED driving circuit in a backlighting inverter consisting of a transistor is input to the base, the collector is connected to the first resistor, the emitter is connected to ground. 제3항에 있어서,The method of claim 3, 상기 트랜지스터의 베이스에 연결된 제1커패시터를 더 포함하는 백라이팅 인버터에서의 LED 구동회로.And a first capacitor connected to the base of the transistor. 제4항에 있어서,The method of claim 4, wherein 일측은 상기 제1커패시터와 베이스 사이에 연결되고, 타측은 접지에 연결되는 제2커패시터를 더 포함하는 백라이팅 인버터에서의 LED 구동회로.One side is connected between the first capacitor and the base, the other side is a LED driving circuit in the backlighting inverter further comprises a second capacitor connected to the ground. 제5항에 있어서,The method of claim 5, 일측은 상기 제1커패시터와 베이스 사이에 연결되고, 타측은 접지에 연결되는 제2저항을 더 포함하는 백라이팅 인버터에서의 LED 구동회로.One side is connected between the first capacitor and the base, the other side LED driving circuit in the backlighting inverter further comprises a second resistor connected to the ground. 제1항 및 제3항 내지 제6항 중 어느 한 항에 있어서,The method according to any one of claims 1 and 3 to 6, 상기 비교부는 비반전단자에 기준전압이 입력되고, 반전단자는 상기 감지저항과 감지저항값 변경수단 사이에 연결되며, 출력단자에서 상기 LED 구동부의 동작을 제어하는 제어신호가 출력되는 OP 앰프인 백라이팅 인버터에서의 LED 구동회로.The comparator is a reference voltage is input to the non-inverting terminal, the inverting terminal is connected between the sensing resistor and the sensing resistance value changing means, the backlighting is an op amp that outputs a control signal for controlling the operation of the LED driver in the output terminal LED drive circuit in the inverter. 제7항에 있어서,The method of claim 7, wherein 상기 OP 앰프는 비반전단자에 램프파형의 기준전압이 입력되고, 출력단자에서 소정 듀티를 갖는 구형파 형태의 제어신호가 출력되는 백라이팅 인버터에서의 LED 구동회로.The OP amplifier is a LED driving circuit in the backlighting inverter that is input to the non-inverting terminal of the ramp waveform reference voltage, and outputs a control signal of the square wave form having a predetermined duty at the output terminal. 제8항에 있어서,The method of claim 8, 상기 LED 구동부는,The LED driver, 일측에 입력전압이 입력되는 인덕터와,An inductor to which an input voltage is input at one side; 게이트에 상기 제어신호가 입력되고, 드레인이 상기 인덕터의 타측과 LED의 애노드 사이에 연결되고, 소스가 접지에 연결되고, 상기 비교부에서 출력되는 제어신호에 따라 구동하는 MOSFET와,A MOSFET input to a gate, a drain connected between the other side of the inductor and an anode of the LED, a source connected to ground, and a MOSFET driven according to a control signal output from the comparator; 일측이 상기 인덕터의 타측과 LED의 애노드 사이에 연결되고, 타측이 접지에 연결되는 제3커패시터; 및A third capacitor having one side connected between the other side of the inductor and the anode of the LED and the other side connected to the ground; And 애노드가 상기 인덕터의 타측에 연결되고, 캐소드가 상기 LED의 애노드와 연결되는 다이오드를 포함하는 백라이팅 인버터에서의 LED 구동회로.An LED driving circuit in a backlighting inverter comprising a diode connected to an anode of the inductor and a cathode connected to the anode of the LED.
KR1020070045833A 2007-05-11 2007-05-11 Circuit for operating led in backlighting inverter KR100859034B1 (en)

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