KR20090035135A - Backlight unit for liquid crystal display device - Google Patents

Backlight unit for liquid crystal display device Download PDF

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Publication number
KR20090035135A
KR20090035135A KR1020070100232A KR20070100232A KR20090035135A KR 20090035135 A KR20090035135 A KR 20090035135A KR 1020070100232 A KR1020070100232 A KR 1020070100232A KR 20070100232 A KR20070100232 A KR 20070100232A KR 20090035135 A KR20090035135 A KR 20090035135A
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South Korea
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led
light emitting
led array
backlight unit
liquid crystal
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KR1020070100232A
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Korean (ko)
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김창인
이무진
이종칠
김재성
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엘지디스플레이 주식회사
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Publication of KR20090035135A publication Critical patent/KR20090035135A/en

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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
    • G02F1/13306—Circuit arrangements or driving methods for the control of single liquid crystal cells
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
    • G09G3/3406—Control of illumination source
    • G09G3/342—Control of illumination source using several illumination sources separately controlled corresponding to different display panel areas, e.g. along one dimension such as lines
    • 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
    • G09G2320/02—Improving the quality of display appearance
    • G09G2320/0233—Improving the luminance or brightness uniformity across the screen

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Nonlinear Science (AREA)
  • General Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Mathematical Physics (AREA)
  • Theoretical Computer Science (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Computer Hardware Design (AREA)
  • Optics & Photonics (AREA)
  • Control Of Indicators Other Than Cathode Ray Tubes (AREA)
  • Liquid Crystal Display Device Control (AREA)
  • Circuit Arrangement For Electric Light Sources In General (AREA)

Abstract

A backlight unit for a liquid crystal display device is provided to reduce a stress in the other circuit and to perform a low cost by reducing the number of LEDs in a configuration of a backlight unit using a LED. A first LED(Light Emitting Diode) array(50a-50e) comprises a plurality of LEDs. A second LED array(50f) comprises a plurality of LEDs and one or more non-light emitting diode(72). The first LED array and the second LED array have one or more configuration. The non-light emitting diode and the LED have the same forward voltage drop property. The second LED array includes three or less non-light emitting diodes. A LED driving part(40) outputs a driving voltage into the first LED array and the second LED array with a PWM(Pulse Width Modulation) signal.

Description

액정표시장치의 백라이트 유닛{Backlight unit for liquid crystal display device}Backlight unit for liquid crystal display device

본 발명은 표시장치의 백라이트 유닛에 관한 것으로서, 특히 발광다이오드(이하 'LED')를 채용하는 액정표시장치의 백라이트 유닛에 관한 것이다. The present invention relates to a backlight unit of a display device, and more particularly, to a backlight unit of a liquid crystal display device employing a light emitting diode (hereinafter, referred to as 'LED').

액정표시장치(Liquid Crystal Display; 이하 'LCD'라 함)는 매트릭스 형태로 배열되어진 다수의 액정 셀들과 이들 액정 셀들 각각에 액정의 회전각도를 제어하여 광 투과량을 조절하기 위한 영상데이터를 공급하기 위한 TFT(박막트랜지스터)가 구비된 액정패널에 백라이트 유닛(Backlight Unit)에서 공급되는 광을 투과시켜 화면에 원하는 화상을 표시하게 된다.Liquid crystal display (hereinafter referred to as "LCD") is a plurality of liquid crystal cells arranged in a matrix form and for supplying the image data for controlling the light transmittance by controlling the rotation angle of the liquid crystal to each of these liquid crystal cells A desired image is displayed on a screen by transmitting light supplied from a backlight unit to a liquid crystal panel provided with a TFT (thin film transistor).

이러한 백라이트 유닛에 사용되는 광원(light source)으로는 주로 냉음극형광램프(Cold Cathode Fluorescent Lamp ; CCFL)가 사용되는데, 이러한 백라이트 유닛은 소형화, 박형화, 경량화의 추세에 있으며, 이러한 추세에 따라 백라이트 유닛에 사용되는 CCFL 대신에 소비전력, 무게, 휘도 등에서 유리한 발광 다이오 드(Light Emitting Diode : 이하 'LED'라 함)가 제안되었다.As a light source used in such a backlight unit, a cold cathode fluorescent lamp (CCFL) is mainly used. Such a backlight unit has a trend of miniaturization, thinning, and weight reduction, and according to this trend, the backlight unit is used. Instead of the CCFL used in the present invention, a light emitting diode (Light Emitting Diode), which is advantageous in terms of power consumption, weight, and luminance, has been proposed.

도 1은 종래 기술에 따른 액정표시장치의 측면 조명 타입(Edge-type) 백라이트 유닛의 회로구성도로서, 백색광 LED를 사용하는 다수개의 LED어레이(10a~10f)와 LED구동부(20)로 구성된다. 1 is a circuit configuration diagram of an edge-type backlight unit of a liquid crystal display according to the prior art, and includes a plurality of LED arrays 10a to 10f and an LED driver 20 using white light LEDs. .

상기 다수개의 LED어레이(10a~10f)는 각각 백색광을 출사하는 다수개의 LED(12)로 구성되며, 도 1의 예시도면에서는 일 LED어레이에 6개의 동일한 LED(12)가 구성되었으나 상기 LED(12)의 구성 개수는 필요에 따라 다양하게 구성할 수 있다.Each of the plurality of LED arrays 10a to 10f includes a plurality of LEDs 12 emitting white light, respectively. In the exemplary drawing of FIG. 1, six identical LEDs 12 are configured in one LED array, but the LEDs 12 ) Can be configured in various ways as needed.

상기 LED구동부(20)는 외부회로부로부터 PWM(Pulse width modulation)신호와 구동전압(VLED)을 입력받아 상기 다수의 LED어레이(10a~10f)의 온/오프(on/off)를 제어하기 위한 회로부로서 일종의 IC(Integrated circuit) 형태로 제작되며, 상기 각각의 LED어레이(10a~10f)로부터의 출력을 피드백(feedback) 받아 PWM신호의 조절을 수행하게 된다. The LED driver 20 receives a pulse width modulation (PWM) signal and a driving voltage (V LED ) from an external circuit to control on / off of the plurality of LED arrays 10a to 10f. The circuit part is manufactured in the form of an IC (Integrated circuit), and receives the output from each of the LED arrays 10a to 10f and performs PWM signal adjustment.

동작을 간략히 살펴보면, 상기 LED구동부(20)는 외부회로로부터 구동전압(VLED)과 PWM신호(PWM)를 입력받는다. In brief, the LED driver 20 receives a driving voltage V LED and a PWM signal PWM from an external circuit.

상기 구동전압(VLED)은 상기 LED(12)의 소비전력과 상기 일 LED어레이에 구성되는 상기 LED(12)의 개수에 따라 결정되는데 일반적으로 7~20V 정도이며, 상기 PWM신호에 따라 상기 스위치(SW)에 의해 상기 다수의 LED어레이(10a~10f)로 인가된다.The driving voltage (V LED ) is determined according to the power consumption of the LED 12 and the number of the LEDs 12 configured in the one LED array, which is generally about 7 to 20 V, and the switch according to the PWM signal. (SW) is applied to the plurality of LED array (10a ~ 10f).

그런데, 상기와 같이 다수개의 LED어레이(10a~10f)로 백라이트 유닛을 구성하여 액정표시장치에 채용하여 사용할 경우, 상기 냉음극형광램프(CCFL)에 비해 상대적으로 고가인 LED에 의해 제조비용이 상승되는 문제점이 있다. By the way, when the backlight unit is composed of a plurality of LED array (10a ~ 10f) as used in the liquid crystal display device as described above, the manufacturing cost is increased by the relatively expensive LED compared to the cold cathode fluorescent lamp (CCFL) There is a problem.

이에 휘도 등에 영향을 크게 미치지 않는 범위 내에서 상기 다수개의 LED어레이(10a~10f) 중 선택된 LED어레이에서 하나 또는 그 이상의 LED를 제거할 수도 있으나 그럴 경우 상기 LED구동부(20)의 피드백입력단(FB1~FB6)에 부하가 걸리게 되어 상기 LED구동부(20)의 수명 감소 등의 문제점이 발생하게 된다. Accordingly, one or more LEDs may be removed from the selected LED arrays among the plurality of LED arrays 10a to 10f within a range that does not significantly affect luminance, etc. In this case, the feedback input terminal FB1 to the LED driver 20 may be removed. The load is applied to the FB6), which causes problems such as a decrease in the life of the LED driver 20.

즉, 예를 들어 도 1에서 동작전압이 3V인 6개의 LED로 구성된 제1LED어레이(10a)의 경우 18V의 구동전압을 인가해 줌으로써 발광 동작되는 경우, 상기 제1LED어레이(10a)에서 2개의 LED를 제거한다고 하면 [구동전압(18V)-(LED개수*3V)=6V]에 의해 제1피드백입력단(FB1)에 6V가 인가되며, 이는 상기 LED구동부(20)로서는 소자의 수명을 단축시키고 이상동작을 유발시킬 수 있는 불필요한 스트레스 요인이 되는 것이다.That is, for example, in the case of the first LED array 10a consisting of six LEDs having an operating voltage of 3 V in FIG. 1, when the light emitting operation is performed by applying a driving voltage of 18 V, the two LEDs in the first LED array 10a are illustrated. If 6V is applied to the first feedback input terminal FB1 by [Drive voltage (18V)-(Number of LEDs * 3V) = 6V], the LED driver 20 shortens the life of the device and causes abnormality. It is an unnecessary stress factor that can cause motion.

이에 본 발명은 상기와 같은 문제점을 해결하기 위해 안출된 것으로서, LED를 이용한 백라이트 유닛의 구성에 있어서 상기 LED의 개수를 줄여 비용 감소를 실현함에 있어서 타 회로에 스트레스 등의 영향을 미치지 않도록 하는 것을 주된 목적으로 한다.Accordingly, the present invention has been made to solve the above problems, in the configuration of the backlight unit using the LED to reduce the number of the LED to reduce the effect of the stress or the like in other circuits in realizing the cost reduction. The purpose.

상기와 같은 목적을 달성하기 위해 본 발명은, 다수개의 발광다이오드로 구성된 제1LED어레이와; 다수개의 발광다이오드와 하나 이상의 비발광 다이오드로 구성된 제2LED어레이를 포함하는 액정표시장치의 백라이트 유닛을 제안한다.The present invention to achieve the above object, the first LED array consisting of a plurality of light emitting diodes; A backlight unit of a liquid crystal display device including a second LED array including a plurality of light emitting diodes and at least one non-light emitting diode is provided.

상기 제1LED어레이와 상기 제2LED어레이는 각각 하나 이상 구성되는 것을 특징으로 한다.At least one of the first LED array and the second LED array may be configured.

상기 비발광 다이오드와 상기 발광다이오드는 순방향 전압강하(Vf)의 특성이 동일한 것을 특징으로 한다.The non-light emitting diode and the light emitting diode are characterized in that the characteristics of the forward voltage drop (Vf) is the same.

상기 제2LED어레이는 상기 비발광 다이오드가 3개 이하로 구성되는 것을 특징으로 한다.The second LED array is characterized in that the non-light emitting diode is composed of three or less.

아울러 상기 백라이트 유닛은, PWM신호를 이용하여 상기 제1LED어레이와 상기 제2LED어레이로 구동전압을 출력하는 LED구동부를 더욱 포함한다.In addition, the backlight unit further includes an LED driver for outputting a driving voltage to the first LED array and the second LED array using a PWM signal.

본 발명에 따르면, 휘도 등 표시품질이 만족되는 범위 내에서 고가의 LED 개수를 줄임으로써 제조비용의 절감 효과를 제공하며, 더불어 회로 소자의 수명단축을 방지하고 안정된 구동성능을 제공하는 효과가 있다.According to the present invention, a reduction in the number of expensive LEDs within a range in which display quality such as luminance is satisfied provides a reduction in manufacturing cost, and also has an effect of preventing shortening of lifespan of a circuit element and providing stable driving performance.

이하 첨부된 도면을 참조하여 본 발명에 대해 상세하게 설명한다.Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

도 2는 본 발명에 따른 액정표시장치의 백라이트 유닛을 도시한 회로구성도로서, LED구동부(40)와 다수개의 LED어레이(50a~50f)로 구성된다. 2 is a circuit diagram illustrating a backlight unit of a liquid crystal display according to the present invention, and includes an LED driver 40 and a plurality of LED arrays 50a to 50f.

상기 LED구동부(40)는 외부회로부로부터 PWM(Pulse width modulation)신호와 구동전압(VLED)을 입력받아 상기 PWM신호에 따라 상기 구동전압(VLED)을 출력하여 상기 다수의 LED어레이(50a~50f)의 온/오프(on/off)를 제어하는 회로부로서 일종의 IC(Integrated circuit) 형태로 제작되며, 상기 각각의 LED어레이(50a~50f)로부터의 출력을 피드백(feedback) 받아 PWM신호의 조절을 수행하게 된다.The LED drive section 40 from an external circuit PWM (Pulse width modulation) signal and the driving voltage (V LED) the input received (LED array and outputting the driving voltage (V LED) of the plurality of response to the PWM signal 50a ~ This circuit part controls 50f) on / off, and is manufactured in the form of an integrated circuit (IC), and receives a feedback from each of the LED arrays 50a to 50f to adjust the PWM signal. Will be performed.

상기 다수개의 LED어레이(50a~50f)는 다시 다수개의 발광다이오드(LED)로만 구성된 제1LED어레이(50a~50e)와, 다수개의 발광다이오드(LED) 및 하나 이상의 비발광 다이오드(72)로 구성된 제2LED어레이(50f)로 구분된다. (각각의 LED어레이(50a~50f)에 구성된 전체 다이오드의 개수는 설명의 편의상 6개로 도시하였다.)The plurality of LED arrays 50a to 50f may further include a first LED array 50a to 50e composed of only a plurality of light emitting diodes (LEDs), a plurality of light emitting diodes (LEDs), and one or more non-light emitting diodes 72. It is divided into 2LED array 50f. (The total number of diodes configured in each LED array 50a to 50f is shown as six for convenience of description.)

상기 제1LED어레이(50a~50e)와 제2LED어레이(50f)의 개수 구성은 설계자에 따라 응용가능하며, 또한 구성된 발광다이오드(LED) 및 비발광 다이오드(72)의 개수 역시 설계자의 응용에 따른다.The number configuration of the first LED array (50a ~ 50e) and the second LED array (50f) is applicable to the designer, and the number of the light emitting diode (LED) and the non-light emitting diode 72 is also dependent on the application of the designer.

아울러 상기 다수개의 LED어레이(50a~50f) 중 도면번호 '72'를 제외한 나머지 다이오드 기호는 모두 발광다이오드(LED)이다. In addition, among the plurality of LED arrays 50a to 50f, the remaining diode symbols except for the reference numeral '72' are all light emitting diodes (LEDs).

이때 상기 제2LED어레이(50f)에 사용되는 비발광 다이오드(72)는 상기 발광다이오드(LED)와 동일한 특성, 좀 더 상세하게는 순방향 전압강하(Vf) 특성이 동일 한 비발광 다이오드라면 종류에 상관없이 적용될 수 있다. In this case, the non-light emitting diode 72 used in the second LED array 50f may be of the same type as the non-light emitting diode having the same characteristics as the light emitting diode (LED), more specifically, the forward voltage drop (Vf) characteristics. Can be applied without.

이처럼 LED어레이에 발광다이오드(LED)와 상기 비발광 다이오드(72)를 혼용하는 이유는 상기 비발광 다이오드(72)에 비해 매우 고가인 상기 발광다이오드(LED)에 있다. The reason why the light emitting diode (LED) and the non-light emitting diode 72 are mixed in the LED array is in the light emitting diode (LED) which is very expensive compared to the non-light emitting diode 72.

액정표시장치에서 하나 이상의 발광다이오드(LED)가 없다고 하더라도 휘도 등의 특성이 만족될 경우 하나 또는 그 이상의 개수에 대해 상기 발광다이오드(LED)를 상기 비발광 다이오드(72)로 대체하는 것이 비용면에서 훨씬 효율적이기 때문이다. 그러나 휘도 저하를 고려하여 상기 제2LED어레이(50f) 내에 3개롤 초과하여 비발광 다이오드(72)를 사용하는 것은 바람직하지 못할 것이다.Even if there is no one or more light emitting diodes (LEDs) in the liquid crystal display device, if the characteristics such as luminance are satisfied, it is cost-effective to replace the light emitting diodes (LEDs) with the non-light emitting diodes 72 for one or more numbers. Because it is much more efficient. However, it may be undesirable to use more than three rolls of the non-light emitting diode 72 in the second LED array 50f in consideration of the decrease in luminance.

이때 상기 비발광 다이오드(72)는 앞서 설명한 바와 같이 발광다이오드(LED)와 동일한 순방향 전압강하(Vf) 특성을 가져야 하는데, 이는 상기 비발광 다이오드(72)와 상기 발광다이오드(LED)의 동일한 동작 특성을 가지도록 하여 상기 모든 LED어레이(50a~50f)가 하나의 구동전압(VLED)에 의해 구동되어야 하기 때문이다.In this case, as described above, the non-light emitting diode 72 should have the same forward voltage drop (Vf) characteristic as that of the light emitting diode (LED), which is the same operating characteristic of the non-light emitting diode 72 and the light emitting diode (LED). This is because all of the LED arrays 50a to 50f must be driven by one driving voltage V LED .

도 1은 종래 기술에 따른 액정표시장치의 측면 조명 타입(Edge-type) 백라이트 유닛의 회로구성도1 is a circuit diagram illustrating a side illumination type backlight unit of a liquid crystal display according to the related art.

도 2는 본 발명에 따른 액정표시장치의 백라이트 유닛을 도시한 회로구성도2 is a circuit diagram illustrating a backlight unit of a liquid crystal display according to the present invention.

<도면의 주요부분에 대한 간단한 설명><Brief description of the main parts of the drawing>

40 : LED구동부 50a~50f : LED어레이40: LED driving part 50a ~ 50f: LED array

VLED : 구동전압 V LED : Drive voltage

Claims (5)

다수개의 발광다이오드로 구성된 제1LED어레이와; A first LED array comprising a plurality of light emitting diodes; 다수개의 발광다이오드와 하나 이상의 비발광 다이오드로 구성된 제2LED어레이Second LED array consisting of multiple light emitting diodes and one or more non-light emitting diodes 를 포함하는 액정표시장치의 백라이트 유닛Backlight unit of the liquid crystal display device comprising a 청구항 제 1 항에 있어서,The method according to claim 1, 상기 제1LED어레이와 상기 제2LED어레이는 각각 하나 이상 구성되는 것을 특징으로 하는 액정표시장치의 백라이트 유닛The backlight unit of the liquid crystal display device, characterized in that at least one of the first LED array and the second LED array. 청구항 제 1 항에 있어서,The method according to claim 1, 상기 비발광 다이오드와는 상기 발광다이오드는 순방향 전압강하(Vf)의 특성이 동일한 것을 특징으로 하는 액정표시장치의 백라이트 유닛The backlight unit of the liquid crystal display device, wherein the light emitting diode and the light emitting diode have the same characteristics as the forward voltage drop Vf. 청구항 제 1 항에 있어서,The method according to claim 1, 상기 제2LED어레이는 상기 비발광 다이오드가 3개 이하로 구성되는 것을 특 징으로 하는 액정표시장치의 백라이트 유닛The second LED array is a backlight unit of the liquid crystal display device, characterized in that the non-light emitting diode is composed of three or less 청구항 제 1 항에 있어서,The method according to claim 1, PWM신호를 이용하여 상기 제1LED어레이와 상기 제2LED어레이로 구동전압을 출력하는 LED구동부LED driver for outputting a driving voltage to the first LED array and the second LED array using a PWM signal 를 포함하는 액정표시장치의 백라이트 유닛Backlight unit of the liquid crystal display device comprising a
KR1020070100232A 2007-10-05 2007-10-05 Backlight unit for liquid crystal display device KR20090035135A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108520720A (en) * 2018-07-13 2018-09-11 四川长虹电器股份有限公司 A kind of LCD TV backlight multi partition control system

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108520720A (en) * 2018-07-13 2018-09-11 四川长虹电器股份有限公司 A kind of LCD TV backlight multi partition control system

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