KR100464022B1 - Apparatus for driving background light of liquid crystal display - Google Patents

Apparatus for driving background light of liquid crystal display Download PDF

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Publication number
KR100464022B1
KR100464022B1 KR10-2001-0072747A KR20010072747A KR100464022B1 KR 100464022 B1 KR100464022 B1 KR 100464022B1 KR 20010072747 A KR20010072747 A KR 20010072747A KR 100464022 B1 KR100464022 B1 KR 100464022B1
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South Korea
Prior art keywords
lcd
backlight
frequency
random signal
driving
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KR10-2001-0072747A
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Korean (ko)
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KR20030041683A (en
Inventor
김재응
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엘지전자 주식회사
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Priority to KR10-2001-0072747A priority Critical patent/KR100464022B1/en
Publication of KR20030041683A publication Critical patent/KR20030041683A/en
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    • GPHYSICS
    • G09EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09GARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20Control 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
    • G09G3/34Control 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
    • G09G3/3406Control of illumination source
    • GPHYSICS
    • G02OPTICS
    • G02FOPTICAL 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
    • G02F1/00Devices 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
    • G02F1/01Devices 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 
    • G02F1/13Devices 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
    • G02F1/133Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333Constructional arrangements; Manufacturing methods
    • G02F1/1335Structural association of cells with optical devices, e.g. polarisers or reflectors
    • GPHYSICS
    • G09EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09GARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2320/00Control of display operating conditions
    • G09G2320/02Improving the quality of display appearance
    • G09G2320/0233Improving the luminance or brightness uniformity across the screen

Abstract

본 발명은 엘씨디(LCD)의 배경 조명을 구동하는 장치에 관한 것으로, 특히 엘씨디의 배경 조명에 의해 소비되는 전류의 양을 줄이기 위해 배경 조명의 온/오프 주기를 빠르게 구동하는 장치에서 배경 조명과 엘씨디의 프레임 주파수의 간섭에 의해 발생하는 줄무늬 간섭 현상을 제거하는 것을 목적으로 한다. 이를 위해 본 발명은 표시제어신호를 입력받아 그에 따른 문자를 프레임 주파수에 동기를 맞추어 표시하는 엘씨디와; 랜덤 신호를 출력하는 랜덤신호 발생기와; 상기 랜덤신호 발생기의 랜덤 신호의 변화에 따라 펄스 폭 변조 발진신호의 구동 주파수를 변조하여 출력하는 피더블유엠(PWM) 발진기와; 전원의 공급을 상기 PWM 발진기로부터 출력되는 펄스 폭 변조 발진신호에 따라 온/오프하는 구동부와; 상기 구동부의 온/오프 동작에 따라 상기 엘씨디의 배경 조명을 점멸하는 발광부로 이루어진 것을 특징으로 한다. 따라서, 본 발명은 PWM 발진기로부터 출력되는 발진 신호의 주파수를 랜덤하게 변화시켜 엘씨디 표면에 나타나는 줄무늬 간섭 현상을 제거하여 엘씨디의 배경 조명 품질을 높일 수 있고 발광 다이오드를 온/오프하여 배경 조명을 점멸 구동하므로 소모되는 전류의 양을 줄여 배터리 사용 시간을 늘리는 효과가 있다.BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for driving a backlight of an LCD (LCD), and in particular, to a device for quickly driving an on / off cycle of a backlight to reduce the amount of current consumed by the backlight of an LCD. An object of the present invention is to eliminate streak interference caused by interference of frame frequencies. To this end, the present invention includes an LCD for receiving a display control signal and displaying the corresponding character in synchronization with the frame frequency; A random signal generator for outputting a random signal; A PWM oscillator for modulating and outputting a driving frequency of a pulse width modulated oscillation signal according to a change of a random signal of the random signal generator; A driver configured to turn on / off a power supply according to a pulse width modulated oscillation signal output from the PWM oscillator; According to the on / off operation of the drive unit is characterized in that consisting of a light emitting unit for blinking the backlight of the LCD. Therefore, the present invention can randomly change the frequency of the oscillation signal output from the PWM oscillator to remove the stray interference phenomenon appearing on the surface of the LCD to increase the backlight quality of the LCD and to turn on / off the LED to flash the backlight. Therefore, the amount of current consumed is reduced to increase battery life.

Description

엘씨디의 배경 조명 구동 장치{APPARATUS FOR DRIVING BACKGROUND LIGHT OF LIQUID CRYSTAL DISPLAY}PCD's backlight driving device {APPARATUS FOR DRIVING BACKGROUND LIGHT OF LIQUID CRYSTAL DISPLAY}

본 발명은 엘씨디(LCD)의 배경 조명을 구동하는 장치에 관한 것으로, 특히 엘씨디의 배경 조명에 의해 소비되는 전류의 양을 줄이기 위해 배경 조명의 온/오프 주기를 빠르게 구동하는 장치에서 배경 조명과 엘씨디의 프레임 주파수의 간섭에 의해 발생하는 줄무늬 간섭 현상을 제거하게 한 엘씨디의 배경 조명 구동 장치에 관한 것이다.BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for driving a backlight of an LCD (LCD), and in particular, to a device for quickly driving an on / off cycle of a backlight to reduce the amount of current consumed by the backlight of an LCD. The present invention relates to an LCD backlight driving apparatus which eliminates streak interference caused by interference of frame frequencies.

도 1은 종래 엘씨디의 배경 조명 구동 장치에 대한 구성을 보인 예시도로서, 표시제어신호를 입력받아 그에 따른 문자를 표시하는 엘씨디(10)와; 전원(VCC)의 공급을 온/오프하는 스위치부(20)의 동작에 따라 상기 엘씨디(10)의 배경 조명을 점멸하는 발광 다이오드(D1, D2)로 구성된 것으로, 이와 같이 구성된 종래 엘씨디의 배경 조명 구동 장치를 설명하면 다음과 같다.1 is an exemplary view showing a configuration of a conventional backlight driving apparatus of the LCD, the LCD 10 receiving the display control signal and displays the corresponding character; Background light of the conventional LCD is configured as the light emitting diodes (D1, D2) to blink the backlight of the LCD 10 in accordance with the operation of the switch unit 20 for turning on / off the supply of the power supply (VCC) The driving device will be described as follows.

도 1의 장치는 매우 단순하여 스위치부의 온/오프에 따라 발광 다이오드에 전류를 공급하는 장치로, 엘씨디의 배경 조명을 구동할 때 엘씨디의 프레임 주파수와 배경 조명을 만드는 발광 다이오드간의 빛 간섭 현상은 발생하지 않지만 전류 소모가 큰 단점이 있다.The device of FIG. 1 is a very simple device that supplies current to a light emitting diode according to on / off of a switch. When driving the backlight of an LCD, light interference between the frame frequency of the LED and the light emitting diode that creates the backlight is generated. However, there is a big drawback of current consumption.

도 2는 종래 엘씨디의 배경 조명 구동 장치에 대한 구성을 보인 예시도로서, 표시제어신호를 입력받아 그에 따른 문자를 표시하는 엘씨디(10)와; 전원(VCC)의 공급을 PWM(Pulse Width Modulation) 발진기(40)로부터 출력된 펄스 파형에 따라온/오프하는 구동부(20)와; 상기 구동부(20)의 동작에 따라 상기 엘씨디(10)의 배경 조명을 점멸하는 발광 다이오드(D1, D2)로 구성된 것으로, 이와 같이 구성된 종래 엘씨디의 배경 조명 구동 장치를 설명하면 다음과 같다.Figure 2 is an exemplary view showing the configuration of the conventional backlight driving apparatus of the LCD, the LCD 10 receiving the display control signal and displays the corresponding character; A driver 20 for turning on / off the supply of the power supply VCC according to the pulse waveform output from the pulse width modulation (PWM) oscillator 40; According to the operation of the driving unit 20, the light emitting diodes D1 and D2 flashing the backlight of the LCD 10. The conventional backlight driving apparatus of the conventional LCD will be described as follows.

도 2의 장치는 도 1의 장치에서 소모되는 전류 문제를 개선하기 위해 배경 조명을 일정한 주기로 온/오프하여 오프되는 시간만큼의 전류를 절약하는 목적으로 사용되지만 엘씨디의 프레임 주파수와 배경 조명의 온/오프 주파수간 중 특정 주파수 대에서 상호 간섭에 의해 줄무늬 간섭이 발생하게 되어 엘씨디의 표시 상태가 매우 불량스러운 문제점이 있다.The device of FIG. 2 is used for the purpose of saving current as much as the off time by turning the backlight on and off at regular intervals to improve the current consumption in the device of FIG. Striped interference occurs due to mutual interference in a specific frequency band among the off frequencies, so the display state of the LCD is very poor.

따라서, 본 발명은 상기와 같은 문제점을 감안하여 창안한 것으로, 배경 조명을 구동하는 발광 다이오드의 온/오프 주기를 랜덤 신호 발생기로부터 출력되는 랜덤 신호에 따라 가변하여 배경 조명의 구동 주파수와 엘씨디의 프레임 주파수의 간섭에 의해 발생하는 줄무늬 간섭 현상을 제거하는 엘씨디의 배경 조명 구동 장치를 제공함에 그 목적이 있다.Accordingly, the present invention has been made in view of the above problems, and the on / off period of the light emitting diode driving the backlight is varied according to the random signal output from the random signal generator, thereby driving the backlight frequency and the frame of the LCD. It is an object of the present invention to provide a backlight driving device of the LCD that eliminates the fringe interference caused by the interference of the frequency.

도 1은 종래의 엘씨디의 배경 조명 구동 장치의 구성을 보인 예시도.1 is an exemplary view showing the configuration of a conventional backlight driving apparatus of the LCD.

도 2는 종래의 또 다른 엘씨디의 배경 조명 구동 장치에 대한 구성을 보인 예시도.Figure 2 is an exemplary view showing a configuration for another conventional backlight backlight driving device of the LCD.

도 3은 본 발명 엘씨디의 배경 조명 구동 장치에 대한 구성을 보인 예시도.Figure 3 is an exemplary view showing the configuration of the backlight driving apparatus of the present invention the LCD.

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

10 : 엘씨디 30 : 구동부10: LCD 30: drive unit

40 : PWM 발진기 50 : 랜덤신호 발생기40: PWM oscillator 50: Random signal generator

상기와 같은 목적을 달성하기 위한 본 발명은, 표시제어신호를 입력받아 그에 따른 문자를 프레임 주파수에 동기를 맞추어 표시하는 엘씨디와; 랜덤 신호를 출력하는 랜덤신호 발생기와; 상기 랜덤신호 발생기의 랜덤 신호의 변화에 따라 펄스 폭 변조 발진신호의 구동 주파수를 변조하여 출력하는 PWM 발진기와; 전원의 공급을 상기 PWM 발진기로부터 출력되는 펄스 폭 변조 발진신호에 따라 온/오프하는 구동부와; 상기 구동부의 온/오프 동작에 따라 상기 엘씨디의 배경 조명을 점멸하는 발광부로 구성한 것을 특징으로 한다.The present invention for achieving the above object, the LCD and receiving the display control signal according to the corresponding characters in synchronization with the frame frequency; A random signal generator for outputting a random signal; A PWM oscillator for modulating and outputting a driving frequency of a pulse width modulated oscillation signal according to a change of a random signal of the random signal generator; A driver configured to turn on / off a power supply according to a pulse width modulated oscillation signal output from the PWM oscillator; According to the on / off operation of the drive unit is characterized in that the light-emitting unit is configured to flash the backlight of the LCD.

이하, 본 발명에 따른 일실시예를 첨부한 도면을 참조하여 상세히 설명하면 다음과 같다.Hereinafter, an embodiment according to the present invention will be described in detail with reference to the accompanying drawings.

도 3은 본 발명 엘씨디 배경 조명 장치의 줄무늬 간섭 발생 제거 장치에 대한 구성을 보인 블록도로서, 이에 도시한 바와 같이 표시제어신호를 입력받아 그에 따른 문자를 프레임 주파수에 동기를 맞추어 표시하는 엘씨디(10)와; 랜덤한 제어신호를 출력하는 랜덤신호 발생기(50)와; 상기 랜덤신호 발생기(50)의 랜덤 신호의 변화에 따라 펄스 폭 변조 발진신호의 구동 주파수를 변조하여 출력하는 PWM 발진기(40)와; 전원(VCC)의 공급을 상기 PWM 발진기(40)로부터 출력되는 펄스 폭 변조 발진신호에 따라 온/오프하는 구동부(20)와; 상기 구동부(20)의 온/오프 동작에 따라 상기 엘씨디(10)의 배경 조명을 점멸하는 발광 다이오드(D1, D2)로 구성한 것으로 본 발명의 일실시예를 설명한다.3 is a block diagram showing the configuration of the interference elimination device of the streaks of the present invention the backlight device, the LCD receives the display control signal as shown therein and displays the resulting characters in synchronization with the frame frequency (10) )Wow; A random signal generator 50 for outputting a random control signal; A PWM oscillator 40 for modulating and outputting a driving frequency of a pulse width modulated oscillation signal according to a change of a random signal of the random signal generator 50; A driver 20 for turning on / off the supply of power VCC according to the pulse width modulated oscillation signal output from the PWM oscillator 40; According to an embodiment of the present invention, the light emitting diodes D1 and D2 flashing the backlight of the LCD 10 according to the on / off operation of the driving unit 20.

PWM 발진기(40)는 미리 결정된 밝기의 조절에 따라 발진신호의 듀티비를 결정하여 발진한다.The PWM oscillator 40 oscillates by determining the duty ratio of the oscillation signal according to the adjustment of the predetermined brightness.

상기 발진 신호의 주파수는 PWM 발진기(40)에 입력되는 랜덤신호 발생기(50)의 출력신호 N과 PWM 발진기(40)의 기본 주파수 fON/OFF와의 곱으로 결정된다.The frequency of the oscillation signal is determined by the product of the output signal N of the random signal generator 50 input to the PWM oscillator 40 and the fundamental frequency f ON / OFF of the PWM oscillator 40.

그리고, 프레임 주파수로 구동되는 엘씨디(10)와 구동부(30)의 온/오프 주파수에 따라 구동되는 배경 조명간의 간섭이 발생하여 엘씨디 표면에 줄무늬가 보일 경우라도 랜덤신호 발생기(50)로부터 출력되는 랜덤신호는 PWM 발진기(40)에 변조 신호로 입력된다.In addition, even when interference is generated between the backlight 10 driven according to the on / off frequency of the LCD 10 driven at the frame frequency and the streaks appear on the LCD surface, the random signal generator 50 is output from the random. The signal is input to the PWM oscillator 40 as a modulation signal.

따라서, PWM 발진기(40)로부터 출력되는 발진 신호의 발진 주파수는 시시각각으로 변하게 된다.Therefore, the oscillation frequency of the oscillation signal output from the PWM oscillator 40 changes every time.

여기서, 주의해야할 점은 랜덤신호 발생기(50)로부터 출력되는 랜덤 신호의 변화 속도는 PWM 발진기(40)의 기본 주파수보다 낮은 주파수로 하고 줄무늬 간섭 현상이 정체되어 육안으로 식별할 수 있는 주파수보다 빠르게 한다.Here, it should be noted that the rate of change of the random signal output from the random signal generator 50 is lower than the fundamental frequency of the PWM oscillator 40 and the banding interference phenomenon is stagnant so that it is faster than the visible frequency. .

결국 엘씨디 표면에는 줄무늬 간섭이 매우 짧은 시간 동안만 존재하게 되어 사용자는 육안으로 이 줄무늬 간섭 현상을 관찰할 수 없게 된다.As a result, streaked interference exists on the surface of the LCD for a very short time, so that the user cannot observe the streaked interference with the naked eye.

다른 경우로 배경 조명을 구동하는 장치의 구동 주파수를 간섭이 발생되지 않는 주파수로 선택하여 제어하는 장치도 가능하나 이 경우 PWM 발진기의 기본 주파수의 안정도가 뛰어나야 한다.In other cases, it is also possible to select and control the driving frequency of the device driving the backlight as a frequency that does not cause interference, but in this case, the stability of the fundamental frequency of the PWM oscillator should be excellent.

또한, 온도 변화에 의한 기본 주파수의 안정도 확보가 중요하게 되며 제품간 PWM 발진기의 기본 주파수 편차 등에 대한 대책이 필요하다.In addition, it is important to secure the stability of the fundamental frequency due to temperature changes and measures for the fundamental frequency deviation of the PWM oscillator between products are necessary.

본 발명은 이러한 편차 문제 및 기본 주파수의 안정도 확보 문제를 해결할 수 있는 장치이다.The present invention is a device that can solve such a problem of deviation and ensuring the stability of the fundamental frequency.

이상에서 상세히 설명한 바와 같이, 본 발명은 PWM 발진기로부터 출력되는 발진 신호의 주파수를 랜덤하게 변화시켜 엘씨디 표면에 나타나는 줄무늬 간섭 현상을 제거하여 엘씨디의 배경 조명 품질을 높일 수 있고 발광 다이오드를 온/오프하여 배경 조명을 점멸 구동하므로 소모되는 전류의 양을 줄여 배터리 사용 시간을 늘리는 효과가 있다.As described in detail above, the present invention can randomly change the frequency of the oscillation signal output from the PWM oscillator to remove the stray interference phenomenon appearing on the surface of the LCD to increase the backlight quality of the LCD and to turn on / off the LED By driving the backlight in a flash mode, the amount of current consumed is reduced, increasing battery life.

Claims (2)

표시제어신호를 입력받아 그에 따른 문자를 프레임 주파수에 동기를 맞추어 표시하는 엘씨디와;An LCD for receiving the display control signal and displaying the corresponding character in synchronization with the frame frequency; 랜덤 신호를 출력하는 랜덤신호 발생기와;A random signal generator for outputting a random signal; 상기 랜덤신호 발생기의 랜덤 신호의 변화에 따라 펄스 폭 변조 발진신호의 구동 주파수를 변조하여 출력하는 피더블유엠(PWM) 발진기와;A PWM oscillator for modulating and outputting a driving frequency of a pulse width modulated oscillation signal according to a change of a random signal of the random signal generator; 전원의 공급을 상기 PWM 발진기로부터 출력되는 펄스 폭 변조 발진신호에 따라 온/오프하는 구동부와;A driver configured to turn on / off a power supply according to a pulse width modulated oscillation signal output from the PWM oscillator; 상기 구동부의 온/오프 동작에 따라 상기 엘씨디의 배경 조명을 점멸하는 발광부로 구성된 것을 특징으로 하는 엘씨디의 배경 조명 구동 장치.The backlight driving apparatus of the LCD, characterized in that consisting of a light emitting unit for blinking the backlight of the LCD in accordance with the on / off operation of the drive unit. 제1항에 있어서, 상기 랜덤신호 발생기로부터 출력되는 랜덤 신호의 변화 속도는 PWM 발진기의 기본 주파수보다 낮은 주파수로 하고 줄무늬 간섭 현상이 관찰되는 주파수보다 높은 주파수로 설정되게 구성된 것을 특징으로 하는 엘씨디의 배경 조명 구동 장치.2. The background of an LCD according to claim 1, wherein the rate of change of the random signal output from the random signal generator is set to a frequency lower than a fundamental frequency of the PWM oscillator and set to a frequency higher than the frequency at which the fringe interference phenomenon is observed. Lighting driving device.
KR10-2001-0072747A 2001-11-21 2001-11-21 Apparatus for driving background light of liquid crystal display KR100464022B1 (en)

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