KR100892431B1 - Circuit for controlling brightness of LCD back light - Google Patents

Circuit for controlling brightness of LCD back light Download PDF

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KR100892431B1
KR100892431B1 KR1020070081317A KR20070081317A KR100892431B1 KR 100892431 B1 KR100892431 B1 KR 100892431B1 KR 1020070081317 A KR1020070081317 A KR 1020070081317A KR 20070081317 A KR20070081317 A KR 20070081317A KR 100892431 B1 KR100892431 B1 KR 100892431B1
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input
voltage
triangular wave
resistor
inverter
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KR1020070081317A
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Korean (ko)
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KR20090016951A (en
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윤창선
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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
    • G09G3/22—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 using controlled light sources
    • G09G3/30—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 using controlled light sources using electroluminescent panels
    • G09G3/32—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 using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED]
    • G09G3/3208—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 using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED] organic, e.g. using organic light-emitting diodes [OLED]
    • G09G3/3225—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 using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED] organic, e.g. using organic light-emitting diodes [OLED] using an active matrix
    • G09G3/3233—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 using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED] organic, e.g. using organic light-emitting diodes [OLED] using an active matrix with pixel circuitry controlling the current through the light-emitting element
    • 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
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B41/00—Circuit arrangements or apparatus for igniting or operating discharge lamps
    • H05B41/14—Circuit arrangements
    • H05B41/26—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc
    • H05B41/28—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc using static converters
    • H05B41/282—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc using static converters with semiconductor devices
    • H05B41/2821—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc using static converters with semiconductor devices by means of a single-switch converter or a parallel push-pull converter in the final stage
    • H05B41/2824—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc using static converters with semiconductor devices by means of a single-switch converter or a parallel push-pull converter in the final stage using control circuits for the switching element
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2320/00—Control of display operating conditions
    • G09G2320/06—Adjustment of display parameters
    • G09G2320/0626—Adjustment of display parameters for control of overall brightness

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Computer Hardware Design (AREA)
  • General Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • Circuit Arrangements For Discharge Lamps (AREA)
  • Discharge-Lamp Control Circuits And Pulse- Feed Circuits (AREA)

Abstract

본 발명은 엘시디 백라이트의 휘도 조절회로에 관한 것이다.The present invention relates to a luminance control circuit of an LCD backlight.

본 발명은 일실시예에 따른 엘시디 백라이트의 휘도 조절회로는, 외부로부터 입력되는 직류전압신호를 입력용의 전압레벨로 변환하는 전압레벨변경부와; 외부로부터 입력되는 일정 듀티의 온/오프신호에 따라 삼각파 전압을 발생하는 삼각파발생부 및 상기 전압레벨변경부로부터 입력되는 직류전압과 상기 삼각파발생부로부터 입력되는 삼각파 전압을 비교하여 출력전류의 듀티를 결정하고 그에 따라 인버터의 출력전류를 조절하는 인버터 제어부를 포함한다. The brightness control circuit of the LCD backlight according to the embodiment includes a voltage level changing unit for converting a DC voltage signal input from the outside into a voltage level for input; According to the on / off signal of a certain duty input from the outside, a triangle wave generator for generating a triangular wave voltage and a DC voltage input from the voltage level changing unit and a triangle wave voltage input from the triangle wave generator are compared with each other. And an inverter controller for determining and adjusting the output current of the inverter accordingly.

본 발명에 의하면 외부로부터 입력되는 PWM 주파수에 동기하여 인버터 내부에서 삼각파를 생성하고 외부에서 입력받은 DC 전압에 상응하게 인버터 출력전류의 온/오프 주기를 조절하여 엘시디 백라이트의 휘도를 정밀하게 조절할 수 있다.According to the present invention, the luminance of the LCD backlight can be precisely controlled by generating a triangular wave in synchronization with the PWM frequency input from the outside and adjusting the on / off period of the inverter output current according to the DC voltage input from the outside. .

LCD, 엘시디, 백라이트, 인버터, 휘도, PWM LCD, LCD, Backlight, Inverter, Luminance, PWM

Description

엘시디 백라이트의 휘도 조절회로 {Circuit for controlling brightness of LCD back light}LCD backlight control circuit {Circuit for controlling brightness of LCD back light}

도 1은 일반적인 엘시디 백라이트용 인버터 장치의 개략적인 블록 구성도.1 is a schematic block diagram of an inverter device for a general LCD backlight;

도 2는 본 발명의 일실시예에 따른 엘시디 백라이트의 휘도 조절회로도.2 is a luminance control circuit diagram of the LCD backlight according to an embodiment of the present invention.

＜도면의 주요부분에 사용된 부호의 설명＞<Description of the code used in the main part of the drawing>

110: 전압레벨변경부110: voltage level change unit

120: 삼각파발생부120: triangle wave generator

130: 삼각파보정부130: Triangle wave government

140: 인버터 제어부140: inverter control unit

본 발명은 엘시디 백라이트의 휘도 조절회로에 관한 것이다. The present invention relates to a luminance control circuit of an LCD backlight.

일반적으로 액정표시장치(Liquid Crystal Display; 이하 "LCD"라 함)는 경량, 박형, 저소비 전력 구동 등의 특징으로 인해 그 응용범위가 점차 넓어지고 있는 추세이다. 이러한 추세에 따라, LCD는 사무자동화 기기, 오디오/비디오 기기 등에 적용되고 있다. 한편, LCD는 매트릭스 형태로 배열되어진 다수의 제어용 스위치들에 인가되는 영상신호에 따라 광빔의 투과량이 조절되어 영상을 표시하게 된다.In general, the liquid crystal display (hereinafter referred to as "LCD") is a trend that the application range is gradually increasing due to the characteristics such as light weight, thin, low power consumption driving. According to this trend, LCD is applied to office automation equipment, audio / video equipment and the like. On the other hand, the LCD displays the image 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.

통상, LCD는 자체적으로 발광하지 못하는 수광소자이므로, 액정판 후면에 투과율이 큰 백라이트(back light)를 설치함으로써 균일한 휘도로 LCD에 표시된 영상을 선명하게 볼 수 있도록 하고 있다. In general, LCDs are light-receiving elements that do not emit light by themselves, and thus, a backlight having a large transmittance is provided on the rear of the liquid crystal panel so that the image displayed on the LCD can be clearly seen with uniform brightness.

LCD 백라이트로는 냉 음극 형광 램프 (Cold Cathode Fluorescent Lamp; 이하 "CCFL"이라 함)가 주로 사용되고 있다.Cold Cathode Fluorescent Lamps (hereinafter referred to as "CCFLs") are commonly used as LCD backlights.

이러한, LCD 백라이트를 구동하는 데에는 인버터라는 장치가 필요한데, 인버터는 직류전원을 고전압의 교류전원으로 변환해서 LCD 백라이트에 인가함으로써 LCD 백라이트를 구동한다.In order to drive the LCD backlight, an apparatus called an inverter is required, and the inverter drives the LCD backlight by converting a DC power into a high voltage AC power and applying the same to the LCD backlight.

도 1은 일반적인 엘시디 백라이트용 인버터 장치의 개략적인 블록 구성도이다. 1 is a schematic block diagram of an inverter device for a general LCD backlight.

도 1에 도시된 바와 같이, 엘시디 백라이트용 인버터 장치는, 인버터 제어부(10)가 마스터 보드(Master Board)의 스위칭부(20)와 슬레이브 보드(Slave Board)의 스위칭부(21)의 스위칭동작을 각각 제어하고, 각 스위칭부(20)(21)가 마스터 보드의 트랜스포머(30)와 슬레이브 보드의 트랜스포머(31)의 입력단 전압을 스위칭하며, 각 트랜스포머(30)(31)는 권선비에 의해 승압된 교류전압을 출력한다.As shown in FIG. 1, in the inverter device for LCD backlight, the inverter controller 10 performs a switching operation of the switching unit 20 of the master board and the switching unit 21 of the slave board. Each of the switching units 20 and 21 switches input voltages of the transformer 30 of the master board and the transformer 31 of the slave board, and the transformers 30 and 31 are boosted by the turns ratio. Output AC voltage.

상기 트랜스포머(30)(31)에서 출력된 교류전압은 램프의 입력단에 인가되어 램프를 구동하도록 이루어져 있다. The AC voltage output from the transformers 30 and 31 is applied to the input terminal of the lamp to drive the lamp.

최근 엘시디의 품질에 대한 요구가 높아지면서 백라이트의 휘도를 정밀하게 제어하는 기술의 개발이 요구되고 있다. Recently, as the demand for quality of LCD increases, development of a technology for precisely controlling the brightness of the backlight is required.

본 발명은 백라이트의 휘도를 정밀하게 제어할 수 있다.The present invention can precisely control the brightness of the backlight.

본 발명은 외부로부터 입력되는 직류전압신호를 입력용의 전압레벨로 변환하여 입력하는 전압레벨변경부와, 외부로부터 입력되는 일정 듀티의 온/오프신호에 따라 삼각파 전압을 발생하는 삼각파발생부 및, 상기 전압레벨변경부로부터 입력되는 직류전압과 상기 삼각파발생부로부터 입력되는 삼각파 전압을 비교하여 출력전류의 듀티를 결정하고 그에 따라 인버터의 출력전류를 조절함으로써 램프의 휘도를 조절하는 인버터 제어부를 포함한다. The present invention provides a voltage level changing unit for converting a DC voltage signal input from the outside into a voltage level for input, a triangular wave generator for generating a triangular wave voltage according to an on / off signal of a predetermined duty input from the outside; And an inverter controller which compares the DC voltage input from the voltage level changing unit with the triangular wave voltage input from the triangle wave generator to determine the duty of the output current and adjusts the output current of the inverter accordingly. .

또한, 본 발명은 외부로부터 입력되는 동작주파수에 따른 하이 또는 로우신호에 따라 캐패시터 용량 보상에 의해 상기 삼각파발생부에서 발생하는 삼각파를 보정하는 삼각파보정부를 더 포함할 수 있다.In addition, the present invention may further include a triangular wave correction unit for correcting the triangular wave generated in the triangular wave generating unit by the capacitor capacitance compensation according to the high or low signal according to the operating frequency input from the outside.

이하, 본 발명의 바람직한 실시예에 대하여 첨부도면을 참조하여 상세히 설명한다. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

도 2는 본 발명의 일실시예에 따른 엘시디 백라이트의 휘도 조절회로도이다.2 is a luminance control circuit diagram of an LCD backlight according to an embodiment of the present invention.

도 2를 참조하면, 본 발명의 일실시예에 따른 엘시디 백라이트의 휘도 조절회로는, 전압레벨변경부(110)와 삼각파발생부(120)와 삼각파보정부(130) 및 인버터 제어부(140)를 포함한다.2, the luminance control circuit of the LCD backlight according to an embodiment of the present invention, the voltage level changing unit 110, the triangular wave generator 120, the triangular wave correction unit 130 and the inverter controller 140 Include.

상기 전압레벨변경부(110)는, 외부로부터 입력되는 출력 전류 듀티를 결정하기 위한 DC 전압신호를 인버터 제어부(140)의 입력용 전압레벨로 변환하기 위한 것으로, 외부로부터 DC 전압신호를 입력받는 직류전압입력단(111)과 인버터 제어부(140)의 11번 입력핀 사이에 연결된 제1 저항(R1)과, 제1 저항(R1)과 인버터 제어부(140)의 11번 입력핀 사이에 연결된 기준전압 입력단(112)를 포함한다. 여기서, 상기 11번 입력핀은 디밍 신호를 만들기 위한 DC 전압 입력 단자이다. 또한, 10번 입력핀은 상기 인버터 제어부(140)의 출력부에 PWM 디밍 신호를 출력하기 위해 기준이 되는 삼각파를 입력하기 위한 단자이다. 즉, 10번 입력핀의 삼각파와 11번 입력핀의 DC 전압이 비교되어 상기 인버터 제어부(140) 출력의 디밍 신호 듀티가 결정된다.The voltage level changing unit 110 converts a DC voltage signal for determining an output current duty input from the outside into an input voltage level of the inverter controller 140, and receives a DC voltage signal from the outside. The first resistor R1 connected between the voltage input terminal 111 and the 11th input pin of the inverter controller 140 and the reference voltage input terminal connected between the first resistor R1 and the 11th input pin of the inverter controller 140. (112). Here, the input pin 11 is a DC voltage input terminal for making a dimming signal. In addition, the input pin 10 is a terminal for inputting a triangular wave as a reference for outputting the PWM dimming signal to the output of the inverter control unit 140. That is, the dimming signal duty of the output of the inverter controller 140 is determined by comparing the triangular wave of the input pin 10 and the DC voltage of the input pin 11.

그리고, 상기 전압레벨변경부(110)는 기준전압 입력단(112)에서 직류전압 입력단(111)과 제1 저항(R1)의 사이를 연결하는 제2 저항(R2)과, 기준전압 입력단(112)에서 제1 저항(R1)과 인버터 제어부(140)의 11번 입력핀 사이를 연결하는 다수의 저항(R3, R4)과, 제1 저항(R1)과 인버터 제어부(140)의 11번 입력핀 사이에서 접지단자를 연결하고 서로 병렬 배치된 저항(R5) 및 캐패시터(C1)를 포함한다.The voltage level changing unit 110 includes a second resistor R2 connecting the DC voltage input terminal 111 and the first resistor R1 at the reference voltage input terminal 112, and the reference voltage input terminal 112. The plurality of resistors R3 and R4 connecting between the first resistor R1 and the 11th input pin of the inverter controller 140 and between the first resistor R1 and the 11th input pin of the inverter controller 140. In the connection to the ground terminal includes a resistor (R5) and a capacitor (C1) arranged in parallel with each other.

상기 삼각파발생부(120)는 외부로부터 입력되는 펄스폭변조(Pulse Width Modulation; 이하, "PWM"이라 함) 주파수에 따른 50% 듀티의 온/오프신호에 따라 삼각파 전압을 발생하여 인버터 제어부(140)에 입력하기 위한 것으로, 외부로부터 50% 듀티의 온/오프신호를 입력받는 온/오프신호 입력단(121), 이 온/오프신호 입력단(121)을 통해 입력되는 50% 듀티의 온/오프신호에 의해 턴온/턴오프되고 출력측 단자가 인버터 제어부(140)의 10번 입력핀에 연결된 스위칭소자(Q1)을 포함한다.The triangular wave generator 120 generates a triangular wave voltage according to an on / off signal of a 50% duty according to a pulse width modulation (PWM) frequency input from the outside. On / Off signal input terminal 121 for receiving a 50% duty on / off signal from the outside, 50% duty on / off signal input through the on / off signal input terminal 121 The switching element Q1 is turned on / off by the output terminal and is connected to the input pin 10 of the inverter controller 140.

또한, 삼각파발생부(120)는, 스위칭소자(Q1)의 출력측과 인버터 제어부(140)의 10번 입력핀 사이에 연결된 기준전압 입력단(112)과, 이 기준전압 입력단(112)에서 스위칭소자(Q1)의 출력측과 인버터 제어부(140)의 10번 입력핀의 사이를 연결하는 저항(R6)과, 스위칭소자(Q1)의 출력측과 인버터 제어부(140)의 10번 입력핀 사이에서 접지단자를 연결하는 다수의 저항(R7, R8) 과 캐패시터(C2) 및, 스위칭소자(Q1)를 구동시키기 위한 다수의 저항(R9~R11) 및 캐패시터(C3)를 포함한다.In addition, the triangular wave generator 120 includes a reference voltage input terminal 112 connected between an output side of the switching element Q1 and an input pin 10 of the inverter controller 140, and a switching element (2) at the reference voltage input terminal 112. The resistor R6 connects between the output side of Q1) and the input pin 10 of the inverter control unit 140, and the ground terminal is connected between the output side of the switching element Q1 and the input pin 10 of the inverter control unit 140. And a plurality of resistors R7 and R8 and a capacitor C2, and a plurality of resistors R9 to R11 and a capacitor C3 for driving the switching element Q1.

상기 삼각파보정부(130)는 외부로부터 입력되는 동작주파수(100/120)에 따른 하이(High) 또는 로우(Low)의 옵션신호에 따라 캐패시터 용량 보상에 의해 상기 삼각파발생부(120)에서 발생하는 삼각파를 보정하기 위한 것이다.The triangular wave compensator 130 is generated by the triangular wave generator 120 by capacitor capacitance compensation according to an option signal of high or low according to an operating frequency (100/120) input from the outside. To correct triangle waves.

이러한, 삼각파보정부(130)는 외부로부터 동작주파수(100/120, 150/180)에 따른 하이 또는 로우의 옵션신호를 입력받는 신호입력단(131)과, 이 신호입력단(131)을 통해 외부로부터 입력되는 하이 또는 로우의 옵션신호에 따라 턴온/턴오프되는 제어용 스위칭소자(Q2)와, 이 제어용 스위칭소자(Q2)에 의해 턴온/턴오프되는 스위칭용 스위칭소자(Q3)와, 일단이 삼각파발생보정부(130)의 출력측에 있는 캐패시터(C2)에 병렬로 연결되고 타단이 스위칭용 스위칭소자(Q3)의 드레인에 연결된 캐패시터(C4)를 포함한다.The triangular wave compensator 130 has a signal input terminal 131 for receiving a high or low option signal according to operating frequencies 100/120, 150/180 from the outside, and the signal input terminal 131 from the outside. A control switching element Q2 that is turned on / off in response to an input high or low option signal, a switching switching element Q3 that is turned on / off by this control switching element Q2, and one end generates a triangular wave The capacitor C4 is connected in parallel to the capacitor C2 on the output side of the correction unit 130 and the other end is connected to the drain of the switching element Q3 for switching.

또한, 제어용 스위칭소자(Q2)를 구동시키기 위한 다수의 저항(R12, R13) 및 캐패시터(C5)와, 스위칭용 스위칭소자(Q3)를 구동시키기 위한 다수의 저항(R14, R15)를 포함한다. 즉, 상기 스위칭소자(Q3)에 풀업 신호를 인가해주기 위해, 기준전압(VREF)으로부터 입력 받는 전압을 저항(R14, R15)을 통해 상기 스위칭소자(Q3)로 출력한다.Also, a plurality of resistors R12 and R13 and a capacitor C5 for driving the control switching element Q2 and a plurality of resistors R14 and R15 for driving the switching switching element Q3 are included. That is, in order to apply the pull-up signal to the switching element Q3, the voltage received from the reference voltage VREF is output to the switching element Q3 through the resistors R14 and R15.

상기 인버터 제어부(140)는 전압레벨변경부(110)로부터 입력되는 DC전압과 삼각파발생부(120)로부터 입력되는 삼각파 전압을 비교하여 출력전류의 듀티를 결정하고 그에 따라 스위칭동작을 제어하여 인버터의 출력전류를 조절함으로써 램프의 휘도를 조절한다.The inverter controller 140 compares the DC voltage input from the voltage level changing unit 110 with the triangular wave voltage input from the triangular wave generator 120 to determine the duty of the output current and controls the switching operation accordingly. The brightness of the lamp is controlled by adjusting the output current.

이하, 상기와 같이 구성된 본 발명의 일실시예에 대한 작용 효과를 첨부된 도면을 참조하여 설명하기로 한다.Hereinafter, with reference to the accompanying drawings will be described the operation and effect of an embodiment of the present invention configured as described above.

외부로부터 입력되는 출력 전류 듀티를 결정하기 위한 DC 전압신호가 상기 전압레벨변경부(110)에서 입력용 전압레벨로 변환되어 인버터 제어부(140)의 11번 입력핀으로 입력된다.The DC voltage signal for determining the output current duty input from the outside is converted into an input voltage level by the voltage level changing unit 110 and input to the input pin 11 of the inverter controller 140.

외부로부터 입력되는 PWM 주파수에 따른 50% 듀티의 온/오프신호에 의해 상기 삼각파발생부(120)에서 스위칭소자(Q1)가 턴온/턴오프를 주기적으로 반복하여 상기 PWM 주파수에 상응하는 삼각파 전압을 생성하고, 이 삼각파 전압이 인버터 제어부(140)의 10번 입력핀으로 입력된다.The switching element Q1 periodically turns on / off the triangular wave voltage corresponding to the PWM frequency by the on / off signal of 50% duty according to the PWM frequency input from the outside. The triangle wave voltage is input to the input pin 10 of the inverter controller 140.

이때, 외부로부터 입력되는 동작주파수(100/120, 150/180)에 따른 하이 또는 로우의 옵션신호에 따라 제어용 스위칭소자(Q2)가 턴온 또는 턴오프되고, 이 제어용 스위칭소자(Q2)에 의해 스위칭용 스위칭소자(Q3)가 턴온 또는 턴오프된다.At this time, the control switching element Q2 is turned on or off according to the high or low option signal according to the operating frequencies 100/120, 150/180 input from the outside, and is switched by the control switching element Q2. Dragon switching element Q3 is turned on or off.

상기 스위칭용 스위칭소자(Q3)의 턴온 또는 턴오프상태에 따라 삼각파발생부(120)의 출력측 캐패시터 용량이 보상됨으로써 삼각파발생부(120)의 삼각파가 보정된다.The triangular wave of the triangular wave generator 120 is corrected by compensating the output capacitor capacity of the triangular wave generator 120 according to the turn-on or turn-off state of the switching switching element Q3.

인버터 제어부(140)는 전압레벨변경부(110)로부터 입력되는 DC전압과 삼각파발생부(120)로부터 입력되는 삼각파 전압을 비교하여 출력전류의 듀티를 결정하고 그에 따라 스위칭동작을 제어하여 인버터의 출력전류를 조절함으로써 램프의 휘도를 조절한다.The inverter controller 140 compares the DC voltage input from the voltage level changing unit 110 with the triangle wave voltage input from the triangle wave generator 120 to determine the duty of the output current and controls the switching operation accordingly to output the inverter. The brightness of the lamp is controlled by adjusting the current.

이와 같이, 본 발명의 상세한 설명에서는 구체적인 실시 예(들)에 관해 설명하였으나, 본 발명의 범주에서 벗어나지 않는 한도 내에서 여러 가지 변형이 가능함은 물론이다. As described above, in the detailed description of the present invention, specific embodiment (s) have been described, but various modifications are possible without departing from the scope of the present invention.

그러므로 본 발명의 범위는 설명된 실시 예(들)에 국한되어 정해져서는 안 되며, 후술하는 특허청구범위 뿐만 아니라 이 특허청구범위와 균등한 것들에 의해 정해져야 한다.Therefore, the scope of the present invention should not be limited to the described embodiment (s), but should be defined by the claims below and equivalents thereof.

본 발명은 외부로부터 입력되는 PWM 주파수에 동기하여 인버터 내부에서 삼각파를 생성하고 외부에서 입력받은 DC 전압에 상응하게 인버터 출력전류의 온/오프 주기를 조절함으로써, 엘시디 백라이트의 휘도를 정밀하게 조절할 수 있는 효과가 있다. The present invention generates a triangular wave in synchronism with the PWM frequency input from the outside and adjusts the on / off period of the inverter output current according to the DC voltage received from the outside, thereby precisely adjusting the brightness of the LCD backlight It works.

Claims (5)

외부로부터 입력되는 직류전압신호를 입력용의 전압레벨로 변환하는 전압레벨변경부와;A voltage level changing unit for converting a DC voltage signal input from the outside into a voltage level for input; 외부로부터 입력되는 50% 듀티의 온/오프신호에 따라 삼각파 전압을 발생하는 삼각파발생부 및Triangular wave generator for generating triangular wave voltage according to on / off signal of 50% duty input from outside; 상기 전압레벨변경부로부터 입력되는 직류전압과 상기 삼각파발생부로부터 입력되는 삼각파 전압을 비교하여 출력 전류의 듀티를 결정하고 그에 따라 인버터의 출력 전류를 조절하는 인버터 제어부를 포함하며,Including an inverter control unit for comparing the DC voltage input from the voltage level changing unit and the triangular wave voltage input from the triangular wave generator to determine the duty of the output current and to adjust the output current of the inverter accordingly, 외부로부터 입력되는 동작주파수에 따른 하이 또는 로우 신호에 따라 캐패시터 용량 보상에 의해 상기 삼각파발생부에서 발생하는 삼각파를 보정하는 삼각파보정부를 더 포함하는 것을 특징으로 하는 엘시디 백라이트의 휘도조절회로.And a triangular wave compensator for compensating a triangular wave generated by the triangular wave generator by capacitor capacitance compensation according to a high or low signal according to an operating frequency input from an external device. 삭제delete 제 1 항에 있어서, 상기 전압레벨변경부는 The method of claim 1, wherein the voltage level changing unit 외부로부터 직류전압신호가 입력되는 직류전압입력단과 상기 인버터에 직렬로 연결된 제1 저항과; A first resistor connected in series with a DC voltage input terminal to which a DC voltage signal is input from the outside and the inverter; 상기 제1 저항과 상기 인버터 제어부 사이에 설정레벨의 기준전압을 입력하는 기준전압 입력단과; A reference voltage input terminal for inputting a reference voltage of a set level between the first resistor and the inverter controller; 상기 기준전압 입력단에서 상기 직류전압 입력단과 상기 제1 저항의 사이를 연결하는 제2 저항과; A second resistor connecting the DC voltage input terminal and the first resistor at the reference voltage input terminal; 상기 기준전압 입력단에서 상기 제1 저항과 상기 인버터 제어부 사이에 연결된 저항과; A resistor connected between the first resistor and the inverter controller at the reference voltage input terminal; 상기 제1 저항과 상기 인버터 제어부 사이에서 접지단자에 연결되고 서로 병렬 배치된 저항 및 캐패시터를 포함하는 엘시디 백라이트의 휘도 조절회로.And a resistor and a capacitor connected to the ground terminal between the first resistor and the inverter controller and arranged in parallel with each other. 제 1 항에 있어서, 상기 삼각파발생부는 The method of claim 1, wherein the triangular wave generator 외부로부터 입력되는 50% 듀티의 온/오프신호에 의해 턴온/턴오프되고 출력측 단자가 상기 인버터 제어부에 연결된 스위칭소자와; A switching element turned on / off by a 50% duty on / off signal input from the outside and having an output terminal connected to the inverter controller; 상기 스위칭소자의 출력측과 상기 인버터 제어부 사이에 설정레벨의 기준전압을 인가하는 기준전압 입력단과; A reference voltage input terminal for applying a reference voltage of a set level between an output side of the switching element and the inverter controller; 상기 기준전압 입력단에서 상기 스위칭소자의 출력측과 상기 인버터 제어부 사이에 연결된 저항과, A resistor connected between an output side of the switching element and the inverter controller at the reference voltage input terminal; 상기 스위칭소자의 출력측과 상기 인버터 제어부 사이에서 접지단자에 연결되는 저항 및 캐패시터를 포함하는 엘시디 백라이트의 휘도 조절회로.And a resistor and a capacitor connected to the ground terminal between the output side of the switching element and the inverter controller. 제 1 항에 있어서, 상기 삼각파보정부는 The method of claim 1, wherein the triangular wave compensator 상기 외부로부터 입력되는 동작주파수에 따른 하이 또는 로우신호에 따라 턴온/턴오프되는 제어용 스위칭소자와; A control switching element turned on / off according to a high or low signal according to an operating frequency input from the outside; 상기 제어용 스위칭소자에 의해 턴온/턴오프되는 스위칭용 스위칭소자 및 A switching switching element turned on / off by the control switching element; 일단이 상기 삼각파발생부의 출력측에 연결되고 타단이 상기 스위칭용 스위칭소자의 출력측 일단에 연결된 캐패시터를 포함하는 엘시디 백라이트의 휘도 조절회로.And a capacitor having one end connected to an output side of the triangular wave generator and the other end connected to an output side end of the switching element for switching.
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