KR20070106176A - Driving circuit of led driver for lcd panel - Google Patents

Driving circuit of led driver for lcd panel Download PDF

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KR20070106176A
KR20070106176A KR1020060038747A KR20060038747A KR20070106176A KR 20070106176 A KR20070106176 A KR 20070106176A KR 1020060038747 A KR1020060038747 A KR 1020060038747A KR 20060038747 A KR20060038747 A KR 20060038747A KR 20070106176 A KR20070106176 A KR 20070106176A
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constant current
constant
led driver
led
driving circuit
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KR1020060038747A
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KR101243144B1 (en
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한경태
박미정
김성은
박성수
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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
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/1336—Illuminating devices
    • G02F1/133602—Direct backlight
    • G02F1/133603—Direct backlight with LEDs
    • 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
    • G02F1/133611—Direct backlight including means for improving the brightness uniformity
    • 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
    • G09G3/36—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 using liquid crystals

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  • Physics & Mathematics (AREA)
  • Nonlinear Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • General Physics & Mathematics (AREA)
  • Mathematical Physics (AREA)
  • Optics & Photonics (AREA)
  • Engineering & Computer Science (AREA)
  • Computer Hardware Design (AREA)
  • Theoretical Computer Science (AREA)
  • Control Of Indicators Other Than Cathode Ray Tubes (AREA)

Abstract

A driving circuit of an LED driver for an LCD panel is provided to comprise a stable LED driver by implementing an LED driver using a constant current IC and/or a constant voltage IC. A driving circuit of an LED(Light Emitting Diode) driver for an LCD(Liquid Crystal Display) panel includes a constant voltage converter(20), a constant current IC(30), and an LED unit(40). The constant voltage converter receives an external source voltage and outputs a predetermined voltage. The constant current IC receives a voltage outputted from the constant voltage converter and outputs a constant current. The LED unit receives the constant current from the constant current IC and illuminates LEDs based on the constant current.

Description

ＬＣＤ 패널용 ＬＥＤ 드라이버의 구동회로{driving circuit of LED driver for LCD panel}Driving circuit of LED driver for LCD panel

도1은 종래 기술에 의한 LCD 패널용 LED 드라이버의 정전류 구동회로를 도시하는 회로도.BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a circuit diagram showing a constant current drive circuit of a LED driver for LCD panel according to the prior art.

도2는 본 발명에 의한 LCD 패널의 LED 드라이버의 정전압 구동회로를 도시하는 블록도.Fig. 2 is a block diagram showing a constant voltage driving circuit of the LED driver of the LCD panel according to the present invention.

도3은 본 발명에 의한 LCD 패널의 LED 드라이버의 정전압 구동회로에서 정전류 IC를 도시하는 회로도.Fig. 3 is a circuit diagram showing a constant current IC in the constant voltage driving circuit of the LED driver of the LCD panel according to the present invention.

< 도면의 주요 부호에 대한 설명 ><Description of Major Symbols in Drawing>

10: 입력측10: input side

20: 정전압 컨버터20: constant voltage converter

30: 정전류 IC30: constant current IC

40: LED부40: LED part

본 발명은 LCD 패널용 LED 드라이버의 구동회로에 관한 것이다. The present invention relates to a driving circuit of an LED driver for an LCD panel.

최근 LCD 패널의 백라이트 유닛의 광원용으로 전력효율이 높고, 광원제어가 용이한 LED를 주로 사용하고 있다. Recently, LEDs having high power efficiency and easy light source control are mainly used for light sources of backlight units of LCD panels.

TFT LCD용 LED는 친환경적이고 색체 재현율이 높은 방향으로 기술이 더욱 발전되고 있으며, 시장에서는 이러한 LED을 요구하고 있다. LEDs for TFT LCDs are being further developed in an environment-friendly and high color reproducibility direction, and the market demands such LEDs.

종래의 정전류 구동회로는 스위치 소자에 흐르는 전류를 정전류 IC에서 감지하여 제어하는 방식으로, 대다수 정전류 IC의 경우 출력전압이 낮은 레벨에서 적용 가능하며, 높은 전압에 적용할 수 있는 소수의 정전류 IC의 경우 일반적으로 사용되는 정전압 IC에 비하여 상대적으로 고가인 경향이 있다.Conventional constant current driving circuits detect and control the current flowing through a switch element in a constant current IC. In the case of most constant current ICs, the output voltage is applicable at a low level, and in the case of a few constant current ICs that can be applied to a high voltage. It tends to be relatively expensive compared to the commonly used constant voltage ICs.

도1은 종래 기술에 의한 LCD 패널용 LED 드라이버의 정전류 구동회로를 도시하는 회로도이다.Fig. 1 is a circuit diagram showing a constant current drive circuit of a LED driver for an LCD panel according to the prior art.

일반적으로 LCD 패널용 LED 드라이버의 구동회로는 정전류 구동회로는 도 1과 같은 IC를 사용하고 있다. In general, the driving circuit of the LED driver for LCD panels uses the IC shown in FIG. 1 as the constant current driving circuit.

상기 정전류 IC를 이용한 LED 드라이버의 정전류 구동회로의 구성을 설명하면 다음과 같다. The configuration of the constant current driving circuit of the LED driver using the constant current IC is as follows.

LCD 패널용 LED 드라이버에서 정전류 구동을 구현하기 위하여, 입력부(1)는 정전류 IC(2)와 연결되어 있다. 상기 정전류 IC(2)의 입력단자들은 VIN, CS, LD, PWM_D로 구성되며, 출력단자는 RT, GATE, VDD, 및 GND로 구성되어 있다. VDD, LD 및 PWM_D 단자들은 콘덴서(C1)를 경유하여 접지되어 있다. 그리고 출력단자 RT는 저항(R1)을 경유하여 접지되어 있다. GATE 및 CS 단자는 저항(R2)을 경유하여 접지되어 있으며, GND 단자는 접지되어 있다. 입력단자(1)와 GATE 단자는 다이오드(3)를 경유하여 상호 연결되어 있다. 상기 다이오드(3)는 LED부(4)와 직렬로 연결되어 있다.In order to implement constant current driving in the LED driver for the LCD panel, the input unit 1 is connected to the constant current IC 2. The input terminals of the constant current IC 2 are composed of VIN, CS, LD, and PWM_D, and the output terminals are composed of RT, GATE, VDD, and GND. The VDD, LD, and PWM_D terminals are grounded via capacitor C1. The output terminal RT is grounded via the resistor R1. The GATE and CS terminals are grounded via resistor R2, and the GND terminal is grounded. The input terminal 1 and the GATE terminal are interconnected via the diode 3. The diode 3 is connected in series with the LED unit 4.

상기와 같은 구성을 갖는 종래기술의 정전류 구동회로에서는, 정전류 IC를 이용하여 정전류 피드백 방식을 구성하여 LED 드라이버를 설계하고 있다. In the conventional constant current drive circuit having the above configuration, the LED driver is designed by configuring the constant current feedback method using the constant current IC.

상기와 같은 구성을 갖는 종래기술의 정전류 구동회로에서는, 정전류 IC를 이용하여 정전류 피드백 방식을 구성하여 LED 드라이버를 설계하고 있다. In the conventional constant current drive circuit having the above configuration, the LED driver is designed by configuring the constant current feedback method using the constant current IC.

그러나 현재 제품으로 출시되고 있는 정전류 IC의 경우, 사용할 수 있는 전압 레벨(출력전압)이 다양하지 못한 문제점이 있다. 시중에 나와 있는 정전류 IC의 경우, 대다수 출력전압이 낮은 화이트 LED나 병렬로 연결되어 낮은 출력전압만으로 동작이 가능한 LED들의 구동용이다. However, there is a problem in that the voltage level (output voltage) that can be used in the case of the constant current IC currently available in the product does not vary. Commercially available constant current ICs are designed to drive white LEDs with low output voltages or LEDs that can be operated in parallel with low output voltages.

한편, 정전압 IC를 채용한 컨버터 회로의 경우는 장시간 동작 시 열로 인한 LED 내부 저항 성분의 감소로 인하여, LED 전류가 감소하는 문제점이 있다. 상기와 같은 LED 전류의 감소로 인하여, 출력전류가 감소하는 관계로 저전류로 인한 LED 휘도가 감소하는 문제점이 있다.On the other hand, the converter circuit employing a constant voltage IC has a problem that the LED current is reduced due to the reduction of the LED internal resistance component due to heat during long time operation. Due to the reduction of the LED current as described above, there is a problem that the LED brightness due to the low current is reduced due to the decrease in the output current.

본 발명은 범용으로 사용되는 정전압 IC 및 정전류 IC를 복합적으로 이용하 여 정전류 구동을 구현할 수 있는 LCD 패널용 LED 드라이버의 구동회로를 제공하는데 있다. The present invention provides a driving circuit of an LED driver for an LCD panel that can implement constant current driving by using a combination of a constant voltage IC and a constant current IC that are used in general.

본 발명은 저비용의 IC를 이용하여 정전압 컨버터 및 전전류 IC를 구성하여 종래의 문제점인 저전류에 따른 LED 휘도 저하의 문제를 해결할 수 있는 LCD 패널용 LED 드러이버의 구동회로를 제공하는데 있다.The present invention is to provide a driving circuit of the LED driver for LCD panel that can solve the problem of lowering the LED brightness due to the low current, which is a conventional problem by configuring a constant voltage converter and all current IC using a low-cost IC.

본 발명은 LCD 패널용 LED 드라이버에 있어서, 외부 전원을 입력받아 소정 전압이 출력되도록 제어하기 위한 정전압 컨버터와; 상기 정전압 컨버터로부터 출력되는 전압을 정전류로 출력하는 정전류 IC와; 수정의 휘도록 발광하기 위한 정전류의 전원을 상기 정전류 IC로부터 공급받는 LED부를 포함한다. The present invention provides an LED driver for an LCD panel, comprising: a constant voltage converter configured to control an output of a predetermined voltage by receiving an external power source; A constant current IC outputting a voltage output from the constant voltage converter at a constant current; And a LED unit for receiving a constant current power supply from the constant current IC to emit light of crystal.

이하, 첨부된 도면에 근거하여 본 발명의 실시예를 상세히 설명한다. Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

도2는 본 발명에 의한 LCD 패널의 LED 드라이버의 구동회로를 도시하는 블록도이다. Fig. 2 is a block diagram showing a driving circuit of the LED driver of the LCD panel according to the present invention.

이에 도시된 바와 같이, 본 발명에 의한 LCD 패널의 LED 드라이버의 구동회로는 외부 전원이 입력되는 입력측(10)과, 출력전압을 일정하게 제어하기 위한 정전압 컨버터(20)와, 출력되는 전압을 일정하게 제어하기 위한 정전류 IC(30)와, 상기 정전류 IC(30)로부터 출력된 전원을 공급받아 소정의 휘도로 발광하기 위한 LED부(40)를 구비하고 있다.As shown in the drawing, the driving circuit of the LED driver of the LCD panel according to the present invention includes an input side 10 to which an external power source is input, a constant voltage converter 20 for uniformly controlling the output voltage, and a constant output voltage. And a LED unit 40 for emitting light at a predetermined brightness by receiving the power output from the constant current IC 30.

도3은 본 발명에 의한 LCD 패널의 LED 드라이버의 구동회로에서 정전류 IC를 도시하는 회로도이다.Fig. 3 is a circuit diagram showing a constant current IC in the driving circuit of the LED driver of the LCD panel according to the present invention.

이에 도시된 바와 같이, 본 발명에 의한 정전류 IC(30)는 Vin, N/C, Rext, PWM 입력단자들을 구비하며, 4개의 Iout 출력 단자들을 구비하고 있다. 여기서, Rext 입력단자는 전류 설정 포인트부(31)를 경유하여 4개의 Iout 출력단자와 각각 연결되어 있다. PWM 입력단자는 4개의 Iout 출력단자와 각각 연결되고, LED부(40)를 경유하여 접지되어 있다. Vin 입력단자는 저항(R1)을 경유하여 Rext 입력단자와 연결되어 있다. 저항(R1)과 Vin 입력단자의 접지는 콘덴서(C1)를 경유하여 접지되어 있다. Vin 입력단자는 전단의 정전압 컨버터(20)와 연결되는 입력부와 직렬로 연결되어 있다. As shown therein, the constant current IC 30 according to the present invention includes Vin, N / C, Rext, and PWM input terminals, and has four Iout output terminals. Here, the Rext input terminal is connected to each of the four Iout output terminals via the current set point portion 31. The PWM input terminals are connected to the four Iout output terminals, respectively, and are grounded via the LED unit 40. The Vin input terminal is connected to the Rext input terminal via a resistor R1. The ground of the resistor R1 and the Vin input terminal is grounded via the capacitor C1. The Vin input terminal is connected in series with the input portion connected to the constant voltage converter 20 of the front end.

이와 같이 구성된 본 발명은 정전압 컨버터(20)에 의하여 일정하게 제어된 출력전압이 입력부(33)로부터 입력되면, 입력된 전원은 정전류 IC(30)의 입력부 Vin을 통하여 입력됨과 동시에, 전류 설정 포인트부(31)의 Rext 단자로 입력된다. 상기와 같이 입력된 전원은 정전류 IC(30)의 전류 설정 포인트부(31)에 의하여 정전류 처리된다. 상기와 같이 정전류 처리된 전원은 정전류 IC(3)의 출력 단자들을 통하여 후단에 연결된 LED부(40)에 입력되어, 상기 LED부(40)가 발광하게 된다. According to the present invention configured as described above, when the output voltage constantly controlled by the constant voltage converter 20 is input from the input unit 33, the input power is input through the input unit Vin of the constant current IC 30, and at the same time, the current set point unit It is input to the Rext terminal of (31). The power input as described above is subjected to constant current processing by the current set point portion 31 of the constant current IC 30. The power subjected to the constant current as described above is input to the LED unit 40 connected to the rear end through the output terminals of the constant current IC 3 so that the LED unit 40 emits light.

종래의 정전류 구동회로의 경우, 정전류 IC의 대다수가 출력전압이 낮은 레벨에서 적용 가능하며, 높은 전압에 적용할 수 있는 소수의 정전류 IC의 경우 일반적으로 사용되는 정전압 IC에 비하여 상대적으로 고가인 경향이 있다. 따라서, 보다 다양한 출력 전압 사양과 가격 면에서의 장점을 얻을 수 있는 회로 구성이다.In the case of the conventional constant current driving circuit, the majority of the constant current IC is applicable at a low level of the output voltage, and the few constant current ICs that can be applied to the high voltage tend to be relatively expensive compared to the commonly used constant voltage IC. have. Therefore, it is a circuit configuration that can obtain advantages in more various output voltage specifications and cost.

상기와 같은 구성과 작용에 따라, LED 드라이버의 장시간 구동시에도 정전류 조정 과장을 경유함으로서 LED 전류가 감소를 방지할 수 있다. 따라서, LED 전류를 방지함으로서, 저전류 문제가 발생하지 않음으로, LED 휘도가 감소하지 않는다.According to the configuration and operation as described above, even when the LED driver is driven for a long time, the LED current can be prevented from being reduced through the constant current adjustment exaggeration. Therefore, by preventing the LED current, the low current problem does not occur, so that the LED brightness does not decrease.

본 발명에서는, 보다 저가의 IC들을 이용하여 정정압 컨버터와 정전류 IC를 구성하여, 종래 기술과 비교하여 보다 간단하고 저렴한 비용으로 저전류에 따를 LED 휘도 감소 문제를 해결할 수 있는 장점이 있다.In the present invention, by using a lower-cost IC to configure a constant voltage converter and a constant current IC, there is an advantage that can solve the problem of LED brightness reduction according to low current at a simpler and lower cost than in the prior art.

이상에 설명한 바와 같이, 본 발명은 정전압 IC와 정전류 IC를 복합적으로 사용하여 LED 드라이버 회로를 구성함으로써 보다 다양한 조건에서 저가의 방식으로 안정적인 LED 드라이버 회로를 구현할 수 있는 장점이 있다.  As described above, the present invention has a merit that a stable LED driver circuit can be implemented in a low cost manner under a variety of conditions by configuring the LED driver circuit using a combination of a constant voltage IC and a constant current IC.

Claims (1)

LCD 패널용 LED 드라이버에 있어서, In the LED driver for the LCD panel, 외부 전원을 입력받아 소정 전압이 출력되도록 제어하기 위한 정전압 컨버터와; A constant voltage converter for receiving an external power and controlling a predetermined voltage to be output; 상기 정전압 컨버터로부터 출력되는 전압을 정전류로 출력하는 정전류 IC와; A constant current IC outputting a voltage output from the constant voltage converter at a constant current; 소정의 휘도록 발광하기 위한 정전류의 전원을 상기 정전류 IC로부터 공급받는 LED부를 포함하는 LCD 패널용 LED 드라이버 구동회로.An LED driver driving circuit for an LCD panel comprising a LED unit for receiving a constant current power for emitting a predetermined bend from the constant current IC.
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CN102014541A (en) * 2010-05-18 2011-04-13 凹凸电子（武汉）有限公司 Light source driving circuit and method for regulating electric power of light source
TWI403875B (en) * 2010-06-17 2013-08-01 O2Micro Int Ltd Light source driving circuit and method for adjusting power of light source
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KR102193202B1 (en) 2018-11-23 2020-12-18 문대식 Control system for led operation apparatus
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CN102014541A (en) * 2010-05-18 2011-04-13 凹凸电子（武汉）有限公司 Light source driving circuit and method for regulating electric power of light source
CN102014541B (en) * 2010-05-18 2011-12-14 凹凸电子（武汉）有限公司 Light source driving circuit and method for regulating electric power of light source
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TWI403875B (en) * 2010-06-17 2013-08-01 O2Micro Int Ltd Light source driving circuit and method for adjusting power of light source
KR102045477B1 (en) 2018-12-06 2019-11-15 주식회사 인스브룩크 System for evaluating platform of ecommerce

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