KR101243143B1 - Back Light Driving Circuit for LCD Panel - Google Patents

Back Light Driving Circuit for LCD Panel Download PDF

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KR101243143B1
KR101243143B1 KR1020060044357A KR20060044357A KR101243143B1 KR 101243143 B1 KR101243143 B1 KR 101243143B1 KR 1020060044357 A KR1020060044357 A KR 1020060044357A KR 20060044357 A KR20060044357 A KR 20060044357A KR 101243143 B1 KR101243143 B1 KR 101243143B1
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voltage
output current
unit
signal
level
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KR1020060044357A
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Korean (ko)
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KR20070111235A (en
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한경태
김성은
박미정
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엘지이노텍 주식회사
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    • 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
    • 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
    • G02F1/136—Liquid crystal cells structurally associated with a semi-conducting layer or substrate, e.g. cells forming part of an integrated circuit
    • 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
    • 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
    • G02F2201/00—Constructional arrangements not provided for in groups G02F1/00 - G02F7/00
    • G02F2201/50—Protective arrangements
    • G02F2201/505—Arrangements improving the resistance to acoustic resonance like noise

Abstract

본 발명은 소음이 발생되지 않는 ＬＣＤ패널의 백라이트 구동회로에 관한 것이다. The present invention relates to a backlight driving circuit of an LCD panel in which noise is not generated.

본 발명은 입력단자의 ON/OFF신호에 의해 ON/OFF되고, 입력되는 출력전류의 레벨에 따라 펄스폭이 증감하는 고주파펄스형 게이트신호를 발생시키는 신호발생부와; 상기 신호발생부의 출력단에 연결되어 전압을 승압시키는 전압승압부와; 상기 전압승압부에 연결되어 승압된 전압에 부하를 거는 부하부와; 상기 부하부의 LED의 출력단에 연결되어 출력전류레벨을 감지하며, 상기 신호발생부에 출력전류레벨을 제공하는 피드백블록과; 상기 피드백블록에 직렬 연결되어 출력전류레벨을 전압레벨로 변환시키는 변환부와; 상기 신호발생부의 출력전류레벨인식단자가 상기 변환부에 연결되고, 상기 신호발생부의 입력단자와 변환부의 사이에 결합된 소음감쇄부를 포함한다. The present invention provides a signal generator for generating a high frequency pulse type gate signal which is turned on and off by an ON / OFF signal of an input terminal and whose pulse width is increased or decreased according to the level of an input output current. A voltage booster connected to an output terminal of the signal generator to boost a voltage; A load unit connected to the voltage booster and configured to load the boosted voltage; A feedback block connected to an output terminal of the LED of the load unit for sensing an output current level and providing an output current level to the signal generator; A converter connected to the feedback block in series to convert an output current level into a voltage level; The output current level recognition terminal of the signal generation unit is connected to the conversion unit, and includes a noise reduction unit coupled between the input terminal and the conversion unit of the signal generation unit.

본 발명에 의하면, 회로에 최초 전원이 투입될 때 FET 게이트에 인가되는 구동펄스 폭을 처음 제로레벨에서 시작하여 서서히 증가하게 함으로써, 컨버터회로의 코일에서 돌입전류가 발생하지 않아 소음이 발생되지 않는 효과가 있다. According to the present invention, when the initial power is applied to the circuit, the drive pulse width applied to the FET gate is gradually increased from the first zero level, so that no inrush current is generated in the coil of the converter circuit so that noise is not generated. There is.

ＬＣＤ패널, LED백라이트, 소음감쇄회로, 싱크(sink)  LCD panel, LED backlight, noise reduction circuit, sink

Description

ＬＣＤ패널의 백라이트 구동회로 {Back Light Driving Circuit for LCD Panel}Back Light Driving Circuit for LCD Panel

도 1은 본 발명의 일실시예를 개략적으로 보인 블록도. 1 is a block diagram schematically showing an embodiment of the present invention.

도 2는 본 발명의 LCD패널용 LED백라이트 회로도. Figure 2 is a LED backlight circuit diagram for the LCD panel of the present invention.

도 3은 도 2의 FET 게이트입력신호, PWM IC의 출력전류인식 파형도. FIG. 3 is a waveform diagram illustrating an output current of a FET gate input signal and a PWM IC of FIG. 2.

도 4는 도 2의 PWM IC의 PWM_D입력신호 및 U1A의 단자의 파형도. 4 is a waveform diagram of a PWM_D input signal and a terminal of U1A of the PWM IC of FIG.

<도면의 주요 부호에 대한 설명> DESCRIPTION OF THE RELATED ART [0002]

PWM_D : LED백라이트 스타팅신호PWM_D: LED backlight starting signal

M1 : FET L1 : 코일M1: FET L1: Coil

LED : 발광다이오드 D1,D2 : 정류다이오드 LED: Light emitting diode D1, D2: Rectifier diode

R1,R2,R3,R4,R5,R7 : 저항 C1 : 커패시터 R1, R2, R3, R4, R5, R7: Resistor C1: Capacitor

TR1 : 트랜지스터 U1A : 오피앰프TR1: Transistor U1A: Op Amp

본 발명은 소음이 발생되지 않는 ＬＣＤ패널의 백라이트 구동회로에 관한 것이다. The present invention relates to a backlight driving circuit of an LCD panel in which noise is not generated.

종래의 ＬＣＤ패널의 LED 백라이트 구동회로는 입력단자의 온/오프신호에 의해 온/오프되고, 입력되는 출력전류의 레벨에 따라 펄스폭이 증감하는 고주파펄스형 게이트신호를 발생시키는 신호발생부와; 상기 신호발생부의 출력단에 연결되어 전압을 승압시키는 전압승압부와; 상기 전압승압부에 연결된 부하부와; 상기 부하부의 LED의 출력단에 연결되어 출력전류레벨을 감지하며, 상기 신호발생부에 출력전류레벨을 제공하는 피드백블록과; 상기 피드백블록에 직렬 연결되어 출력전류레벨을 전압레벨로 변환시키는 변환부와; 상기 신호발생부의 출력전류레벨인식 단자는 변환부에 연결되며, 상기 FET의 게이트에 고주파펄스형 게이트 신호를 인가하여 LED를 ON시켜서 LＣＤ패널 LED백라이트를 구현한다. The LED backlight driving circuit of the conventional LCD panel includes a signal generator for generating a high frequency pulse type gate signal which is turned on / off by an on / off signal of an input terminal and whose pulse width increases or decreases according to the level of an input output current; A voltage booster connected to an output terminal of the signal generator to boost a voltage; A load unit connected to the voltage boosting unit; A feedback block connected to an output terminal of the LED of the load unit for sensing an output current level and providing an output current level to the signal generator; A converter connected to the feedback block in series to convert an output current level into a voltage level; The output current level recognition terminal of the signal generator is connected to the converter, and the LED is turned on by applying a high frequency pulsed gate signal to the gate of the FET to implement the LCD panel LED backlight.

그러나, 신호발생부의 입력단자가 온 되면, 즉시 출력전류레벨인식단자가 높아지고, 첫 번째 펄스부터 큰 폭을 가진 전압승압부의 게이트입력신호가 전압승압부의 게이트에 인가되므로, 전압승압부의 누설성분에 의해 교류를 차단하는 부분에서 돌입전류가 발생하여 소음이 발생하는 문제점이 있었다. However, when the input terminal of the signal generator is turned on, the output current level recognition terminal immediately rises, and the gate input signal of the voltage booster having a large width from the first pulse is applied to the gate of the voltage booster. There was a problem that the noise is generated by the inrush current is generated in the part blocking the AC.

본 발명은 ＬＣＤ패널 LED백라이트를 구동하기 위해 최초전원 투입시 소음이 발생되지 않는 ＬＣＤ패널의 LED백라이트 구동회로를 제공하는 데에 있다. An object of the present invention is to provide an LED backlight driving circuit of an LCD panel in which noise is not generated when the initial power is turned on to drive an LCD panel LED backlight.

본 발명은 입력단자의 ON/OFF신호에 의해 ON/OFF되고, 입력되는 출력전류의 레벨에 따라 펄스폭이 증감하는 고주파펄스형 게이트신호를 발생시키는 신호발생부와; 상기 신호발생부의 출력단에 연결되어 전압을 승압시키는 전압승압부와; 상기 전압승압부에 연결되어 승압된 전압에 부하를 거는 부하부와; 상기 부하부의 LED의 출력단에 연결되어 출력전류레벨을 감지하며, 상기 PWM IC에 출력전류레벨을 제공하는 피드백블록과; 상기 피드백블록에 직렬 연결되어 출력전류레벨을 전압레벨로 변환시키는 변환부와; 상기 신호발생부의 출력전류레벨인식단자가 상기 변환부에 연결되고, 상기 신호발생부의 입력단자와 변환부의 사이에 결합된 소음감쇄부를 포함한다. The present invention provides a signal generator for generating a high frequency pulse type gate signal which is turned on and off by an ON / OFF signal of an input terminal and whose pulse width is increased or decreased according to the level of an input output current. A voltage booster connected to an output terminal of the signal generator to boost a voltage; A load unit connected to the voltage booster and configured to load the boosted voltage; A feedback block connected to an output terminal of the LED of the load unit for sensing an output current level and providing an output current level to the PWM IC; A converter connected to the feedback block in series to convert an output current level into a voltage level; The output current level recognition terminal of the signal generation unit is connected to the conversion unit, and includes a noise reduction unit coupled between the input terminal and the conversion unit of the signal generation unit.

이하, 본 발명의 실시예를 도면을 토대로 상세히 설명한다. Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

도 1은 본 발명의 일실시예를 개략적으로 보인 블록도이고, 도 2는 본 발명의 LCD패널용 LED백라이트 회로도이며, 도 3은 도 2의 FET 게이트입력신호, PWM IC의 출력전류인식 파형도이고, 도 4는 도 2의 PWM IC의 PWM_D입력신호 및 U1A의 단자의 파형도이다. 1 is a block diagram schematically showing an embodiment of the present invention, Figure 2 is a LED backlight circuit diagram for the LCD panel of the present invention, Figure 3 is a waveform diagram of the output current recognition of the FET gate input signal, PWM IC of Figure 2 4 is a waveform diagram of a PWM_D input signal of the PWM IC of FIG. 2 and a terminal of U1A.

먼저, 도 1 및 도 2에 도시된 바와 같이 본 발명은 입력단자의 ON/OFF신호에 의해 ON/OFF되고, 입력되는 출력전류의 레벨에 따라 펄스폭이 증감하는 고주파펄스형 게이트신호를 발생시키는 신호발생부(1)와, 신호발생부(1)의 출력단에 연결되어 전압을 승압시키는 전압승압부(3)와 전압승압부(3)에 연결되어 승압된 전압에 부하 를 거는 부하부(5)와, 부하부(5)의 LED의 출력단에 연결되어 출력전류레벨을 감지하며, 신호발생부(1)에 출력전류레벨을 제공하는 피드백블록(7)과, 피드백블록에 직렬 연결되어 출력전류레벨을 전압레벨로 변환시키는 변환부(9)와, 신호발생부(1)의 출력전류레벨인식단자(P1)가 변환부(9)에 연결되고, 신호발생부(1)의 입력단자(P2)와 변환부(9)의 사이에 결합된 소음감쇄부(10)를 포함하여 구성된다. First, as shown in FIGS. 1 and 2, the present invention generates a high frequency pulse type gate signal which is turned on and off by an ON / OFF signal of an input terminal and whose pulse width is increased or decreased according to the level of an input output current. A voltage booster 3 connected to the signal generator 1 and an output terminal of the signal generator 1 to boost the voltage, and a load unit 5 connected to the voltage booster 3 to load the voltage boosted thereon; And a feedback block 7 connected to the output terminal of the LED of the load unit 5 to detect the output current level and providing an output current level to the signal generator 1, and a series connected to the feedback block in series. A converter 9 for converting a level into a voltage level, and an output current level recognition terminal P1 of the signal generator 1 are connected to the converter 9, and an input terminal P2 of the signal generator 1 is connected. ) And a noise reduction unit 10 coupled between the conversion unit 9.

여기서, 신호발생부(1)는 출력전류레벨인식단자(P1)와 PWM_D단자(P2)와 출력단자(Q1)를 갖는 PWM IC이고, 전압승압부(3)는 FET(M1)와 코일(L1)과 다이오드(D2)로 구성되며, 부하부(5)는 저항(R7)과 LED1, LED2로 구성되고, 변환부(9)는 다수개의 저항(R2, R3, R4)이다. Here, the signal generator 1 is a PWM IC having an output current level recognition terminal P1, a PWM_D terminal P2, and an output terminal Q1, and the voltage booster 3 is a FET M1 and a coil L1. ) And a diode (D2), the load unit 5 is composed of a resistor (R7) and LED1, LED2, the converter 9 is a plurality of resistors (R2, R3, R4).

그리고, 소음감쇄부(10)는 출력전류레벨인식단자(P1)의 전압레벨을 초기화시키는 싱크부와, 싱크부에 연결되어 PWM_D단자(P2)의 ON/OFF신호를 필터링하는 R-C필터링부(11)와, R-C필터링부(11)의 출력전압을 변환부(9)에 바이패스시키는 볼테이지팔로우부를 포함한다. 여기서, 싱크부는 트랜지스터(TR1)이고, R-C필터링부는 싱크부에 직렬연결된 저항(R1)과 캐패시터(C1)로 구성되고, 볼테이지팔로우부는 오피앰프(U1A)이다.The noise reduction unit 10 includes a sink for initializing the voltage level of the output current level recognition terminal P1, and an RC filter 11 connected to the sink to filter the ON / OFF signal of the PWM_D terminal P2. And a voltage follower for bypassing the output voltage of the RC filter 11 to the converter 9. Here, the sink portion is a transistor TR1, the R-C filtering portion is composed of a resistor R1 and a capacitor C1 connected in series with the sink portion, and the voltage follower portion is an op amp U1A.

도 2에 도시된 바와 같이, 본 발명은 다음과 같이 동작된다. PWM IC의 PWM_D단자(P2)에 온신호를 투입하기 전에는 부하(LED1,LED2)전류가 제로이므로, PWM IC의 출력전류레벨인식단자(P1)는 하이레벨이다. 이때, PWM_D단자(P2)에서 온 신호가 입력되면, PWM IC의 출력단자(Q1)에서 FET(M1)의 게이트입력신호가 발생한다. As shown in Fig. 2, the present invention operates as follows. Before the ON signal is input to the PWM_D terminal P2 of the PWM IC, the load (LED1, LED2) current is zero, so the output current level recognition terminal P1 of the PWM IC is high level. At this time, when the signal from the PWM_D terminal P2 is input, the gate input signal of the FET M1 is generated at the output terminal Q1 of the PWM IC.

여기서, PWM IC는 PWM_D단자(P2)신호가 온 되면, 출력전류레벨인식단자(P1)의 전압레벨이 낮으면 펄스폭이 좁은 펄스의 FET 게이트신호를 출력하고, 높으면 펄스폭이 넓은 FET 게이트신호를 출력하는 IC이다. Here, the PWM IC outputs a FET gate signal of a narrow pulse width when the voltage level of the output current level recognition terminal P1 is low when the PWM_D terminal P2 signal is turned on, and a FET gate signal having a wide pulse width when the PWM_D terminal P2 is turned on. It is an IC that outputs.

피드백블록(FEEDBACK BLOCK)은 부하(LED)에 흐르는 전류가 크면 출력전류를 줄이고, 부하(LED)에 흐르는 전류가 작으면 출력전류를 크게 하는 회로이다. The feedback block is a circuit that reduces the output current when the current flowing through the load (LED) is large and increases the output current when the current flowing through the load (LED) is small.

이 신호가 FET(M1)의 게이트에 인가되면 V5의 DC전압은 코일(L1),다이오드(D2),커패시터(C2) 그리고 부하부(LED1,LED2,R7)의 작용에 의해 승압되어 LED1, LED2 그리고 저항(R7)에 가해지고 LED1, LED2가 발광되므로, LCD패널은 LED백라이트 된다. When this signal is applied to the gate of the FET M1, the DC voltage of V5 is stepped up by the action of the coil L1, diode D2, capacitor C2 and the load portions LED1, LED2, R7, LED1, LED2. Since the resistor R7 is applied and LEDs 1 and 2 emit light, the LCD panel is backlit.

이때, 부하(LED1,LED2)에 흐르는 전류의 일부는 피드백블록회로를 거치고 저항(R2),저항(R3),저항(R4)을 거치면서 전압레벨로 변하여 PWM IC의 출력전류레벨인식단자(P1)에 인가되는데, 이 출력전류레벨인식단자(P1)의 전압레벨은 부하(LED1,LED2)의 전류가 증가하면 감소하고, 감소하면 증가하는 방법으로 인가되어 있다. At this time, a part of the current flowing through the loads LED1 and LED2 passes through the feedback block circuit and changes to the voltage level while passing through the resistors R2, R3, and R4, and the output current level recognition terminal P1 of the PWM IC. The voltage level of the output current level recognition terminal P1 decreases as the current of the loads LED1 and LED2 increases, and increases when it decreases.

PWM IC는 입력단자(P1)의 전압레벨이 낮으면 출력단자(Q1)에서 발생하는 고주파펄스의 듀티를 작게하여 부하(LED)전류를 줄여서 LED를 어둡게하고, 입력단자(P1)의 전압레벨이 높으면 출력단자(Q1)에서 발생하는 고주파펄스의 듀티를 크게하여 부하(LED)전류를 크게하여 LED를 밝게하는 방법으로 작용하여, 항상 균일한 밝기의 LCD패널 LED백라이트가 구현되게 한다. When the voltage level of the input terminal P1 is low, the PWM IC reduces the load (LED) current by reducing the duty of the high frequency pulse generated at the output terminal Q1, thereby dimming the LED, and increasing the voltage level of the input terminal P1. If it is high, the duty of the high frequency pulse generated at the output terminal Q1 is increased to increase the load (LED) current to brighten the LED, so that the LCD panel LED backlight of uniform brightness is always realized.

그러므로, PWM_D단자(P2)가 오프되어 있는 동안에는, PWM_D단자(P2)가 제로 레벨에 있으므로, 트랜지스터(TR1)가 도통하여 오피앰프(U1A)의 입력단자(a)가 저항(R5)을 통해 싱크되므로, 입력단자(a)가 제로레벨이 되고, 따라서, 출력단자(b)도 제로레벨이 되어, PWM IC의 출력전류레벨인식단자(P1)가 제로레벨이 되므로, PWM IC의 출력단자(Q1)는 게이트구동펄스를 출력하지 않는다. Therefore, since the PWM_D terminal P2 is at zero level while the PWM_D terminal P2 is off, the transistor TR1 is turned on so that the input terminal a of the operational amplifier U1A sinks through the resistor R5. Therefore, since the input terminal a becomes the zero level, the output terminal b also becomes the zero level, and thus the output current level recognition terminal P1 of the PWM IC becomes the zero level, so that the output terminal Q1 of the PWM IC ) Does not output the gate drive pulse.

이때, PWM_D단자(P2)에 온 신호가 입력되면, 즉시, 트랜지스터(TR1)가 오프되므로, 입력단자(a)의 전압레벨이 저항(R1)-커패시터(C1)의 시정수에 따라 서서히 증가하게 되고, 이에 따라 단자(b)의 전압도 서서히 증가하므로, 저항(R3),저항(R4) 통해, PWM IC의 단자(P1)의 레벨도 서서히 증가하게 되므로, PWM IC의 출력단자(Q1)는 처음에는 매우 작은 펄스폭으로 시작하여 점차 펄스폭이 큰 FET(M1)의 게이트신호를 출력하게 되므로, 컨버터회로 내부의 누설이 최소화되어 코일(L1)에서 돌입전류가 발생하지 않아 soft start된다. At this time, when the ON signal is input to the PWM_D terminal P2, the transistor TR1 is turned off immediately, so that the voltage level of the input terminal a gradually increases with the time constant of the resistor R1-capacitor C1. Accordingly, since the voltage of the terminal b gradually increases, the level of the terminal P1 of the PWM IC also gradually increases through the resistors R3 and R4, so that the output terminal Q1 of the PWM IC At first, the gate signal of the FET M1, which starts with a very small pulse width and gradually increases, outputs a gate signal. Therefore, leakage in the converter circuit is minimized, so that inrush current does not occur in the coil L1, thereby soft starting.

즉, PWM_D신호가 온 되기 전에는 오피앰프(U1A)의 입력단자(a)에 DC레벨이 제로로 된 상태에서 PWM_D신호가 온 되면 서서히 증가되어 오피앰프(U1A)의 출력단자(b)의 DC레벨이 서서히 증가하게 되어 소음이 발생되지 않는다. That is, before the PWM_D signal is turned on, when the PWM_D signal is turned on while the DC level is zero at the input terminal a of the operational amplifier U1A, the DC level of the output terminal b of the operational amplifier U1A is gradually increased. This gradually increases and no noise is generated.

도 3은 FET 게이트입력신호에 따른 파형①과 PWM IC의 출력전류레벨인식에 따른 파형②을 보인 도면이다. 즉, 도 3에서 PWM_D단자(P2)가 온 되면 PWM IC의 출력전류레벨인식단자(P1)의 레벨이 서서히 증가하고, 따라서 출력단자(Q1)에서의 FET(M1)의 게이트입력신호의 펄스폭이 아주 서서히 커지고 있는 것을 볼 수 있다. 이렇게, PWM_D단자(P2)가 온 되었을 때, PWM IC의 출력단자(Q1)에서 발생하는 FET(M1)의 게이트신호의 듀티를 점차적으로 늘려가면서 FET(M1)를 구동하기 때문에, 결국 컨버터내의 누설성분에 의한 순간적인 효과를 둔감시켜서 코일(L1)에서의 소음발생을 감소시키게 된다. FIG. 3 is a diagram showing waveforms ① according to the FET gate input signal and waveforms ② according to the output current level recognition of the PWM IC. That is, when the PWM_D terminal P2 is turned on in FIG. 3, the level of the output current level recognition terminal P1 of the PWM IC gradually increases, and thus the pulse width of the gate input signal of the FET M1 at the output terminal Q1. You can see this growing very slowly. In this way, when the PWM_D terminal P2 is turned on, the FET M1 is driven while gradually increasing the duty of the gate signal of the FET M1 generated at the output terminal Q1 of the PWM IC. By reducing the instantaneous effect of the components to reduce the noise generated in the coil (L1).

또한, 도 4는 PWM_D단자(P2)에 온 신호가 서서히 입력되는 상태를 보이는 것으로, 오피앰프(U1A)가 구성하고 있는 오피앰프(U1A) 회로 안에 다이오드(D1)를 추가하여, PWM_D단자(P2)가 OFF되었을 때, 단자(b)의 전압레벨이 서서히 줄어들지 않고 순간적으로 제로레벨이 되므로 LED백라이트가 즉시 제거된다. 4 shows a state in which the ON signal is gradually input to the PWM_D terminal P2. The diode D1 is added to the op amp U1A circuit constituted by the op amp U1A, and the PWM_D terminal P2 is added. When () is turned off, the LED backlight is immediately removed because the voltage level of the terminal (b) does not decrease gradually but becomes zero level instantaneously.

본 발명에 의하면, LＣＤ패널 LED백라이트 구동회로는 PWM IC 출력전류레벨 인식전압(Feedback Reference 전압- 기준전압)을 초기에 경사를 가지고 상승하는 구간을 가지도록 회로를 구현할 수 있으므로, PWM_D신호가 ON되면 PWM IC의 게이트 신호의 듀티를 점차적으로 늘려가면서 FET를 구동하기 때문에, 결국 컨버터내의 누설성분에 의한 순간적인 효과를 둔감시켜서 코일에서의 소음발생을 감소시키게 된다. 또한, PWM_D신호 ON되면 PWM IC의 게이트 신호가 점차적으로 듀티를 늘려가므로, 순간적으로 큰 입력전류에 의한 돌입전류(Inrush)의 발생을 줄이는 효과가 있다. According to the present invention, the LCD panel LED backlight driving circuit can be implemented to have a section in which the PWM IC output current level recognition voltage (Feedback Reference voltage-reference voltage) rises with an initial slope, so that the PWM_D signal is turned on. By driving the FET while gradually increasing the duty of the gate signal of the PWM IC, the noise generated in the coil is reduced by reducing the instantaneous effect of the leakage component in the converter. In addition, when the PWM_D signal is turned on, the gate signal of the PWM IC gradually increases the duty, thereby reducing the inrush current caused by a large input current.

즉, 본 발명에 의하면, Soft Start 방식을 적용하므로 최초 전원 투입시 컨버터회로의 코일에서 돌입전류가 발생하지 않아 소음이 발생하지 되지 않는 매우 유용한 발명이다. That is, according to the present invention, since the soft start method is applied, the inrush current does not occur in the coil of the converter circuit at the first power-on, so that the noise is not generated.

Claims (6)

입력단자의 ON/OFF신호에 의해 ON/OFF되고, 입력되는 출력전류의 레벨에 따라 펄스폭이 증감하는 고주파펄스형 게이트신호를 발생시키는 신호발생부와; A signal generator which is turned on / off by an ON / OFF signal of an input terminal and generates a high frequency pulse type gate signal whose pulse width is increased or decreased in accordance with the level of an input output current; 상기 신호발생부의 출력단에 연결되어 전압을 승압시키는 전압승압부와; A voltage booster connected to an output terminal of the signal generator to boost a voltage; 상기 전압승압부에 연결되어 승압된 전압에 부하를 거는 부하부와; A load unit connected to the voltage booster and configured to load the boosted voltage; 상기 부하부의 LED의 출력단에 연결되어 출력전류레벨을 감지하며, PWM IC에 출력전류레벨을 제공하는 피드백블록과; A feedback block connected to an output terminal of the LED of the load unit for sensing an output current level and providing an output current level to a PWM IC; 상기 피드백블록에 직렬 연결되어 출력전류레벨을 전압레벨로 변환시키는 변환부와; A converter connected to the feedback block in series to convert an output current level into a voltage level; 상기 신호발생부의 출력전류레벨인식단자가 상기 변환부에 연결되고, 상기 신호발생부의 입력단자와 변환부의 사이에 결합된 소음감쇄부를 포함하는 ＬＣＤ패널의 LED 백라이트 구동회로.The output current level recognition terminal of the signal generation unit is connected to the conversion unit, LED backlight driving circuit of the LCD panel including a noise reduction unit coupled between the input terminal and the conversion unit of the signal generation unit. 제 1항에 있어서, 상기 소음감쇄부는 출력전류레벨인식단자의 전압레벨을 초기화시키는 싱크부와; The noise canceling unit of claim 1, further comprising: a sink unit configured to initialize a voltage level of the output current level recognition terminal; 상기 싱크부에 연결되어 PWM_D ON/OFF신호를 필터링하는 R-C필터링부와; An R-C filtering unit connected to the sink unit to filter the PWM_D ON / OFF signal; 상기 R-C필터링부의 출력전압을 변환부에 바이패스시키는 볼테이지팔로우부를 포함하는 것을 특징으로 하는 ＬＣＤ패널의 LED 백라이트 구동회로.And a voltage follower for bypassing the output voltage of the R-C filtering part to a converter part. 제 2항에 있어서, 싱크부는 TR인 것을 특징으로 하는 ＬＣＤ패널의 LED 백라이트 구동회로.The LED backlight driving circuit of the LCD panel according to claim 2, wherein the sink portion is TR. 제 2항에 있어서, R-C필터링부는 상기 싱크부에 직렬연결된 저항과 캐패시터로 구성된 것을 특징으로 하는 ＬＣＤ패널의 LED 백라이트 구동회로.The LED backlight driving circuit of the LCD panel of claim 2, wherein the R-C filtering unit comprises a resistor and a capacitor connected in series with the sink unit. 제 2항에 있어서, 볼테이지팔로우부는 오피앰프인 것을 특징으로 하는 ＬＣＤ패널의 LED 백라이트 구동회로.The LED backlight driving circuit of the LCD panel according to claim 2, wherein the voltage follower unit is an op amp. 제 2항에 있어서, PWM_D신호가 오프됨과 동시에 출력전류레벨이 제로레벨로 떨어지도록, 상기 볼테이지팔로우부의 출력단에 설치되는 다이오드를 더 포함하는 것을 특징으로 하는 ＬＣＤ패널의 백라이트 구동회로. 3. The backlight drive circuit of an LCD panel according to claim 2, further comprising a diode provided at an output end of said voltage follower portion such that the PWM_D signal is turned off and the output current level drops to zero level.
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Publication number Priority date Publication date Assignee Title
KR20200028465A (en) * 2017-07-19 2020-03-16 선전 차이나 스타 옵토일렉트로닉스 세미컨덕터 디스플레이 테크놀로지 컴퍼니 리미티드 Output voltage regulation circuit and liquid crystal display device
KR102318646B1 (en) * 2017-07-19 2021-10-28 선전 차이나 스타 옵토일렉트로닉스 세미컨덕터 디스플레이 테크놀로지 컴퍼니 리미티드 Output voltage regulation circuit and liquid crystal display device

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