JP2007121927A - Backlight device, and liquid crystal display device - Google Patents

Backlight device, and liquid crystal display device Download PDF

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JP2007121927A
JP2007121927A JP2005317175A JP2005317175A JP2007121927A JP 2007121927 A JP2007121927 A JP 2007121927A JP 2005317175 A JP2005317175 A JP 2005317175A JP 2005317175 A JP2005317175 A JP 2005317175A JP 2007121927 A JP2007121927 A JP 2007121927A
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liquid crystal
light
fluorescent tube
crystal panel
backlight device
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Shiho Cho
志芳 張
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Sharp Corp
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a backlight device capable of reducing the number of light emitting diodes needed to prevent unevenness of a light emission color on the whole device by increasing the light emission intensity of a fluorescent lamp and also preventing an electric power efficiency from being degraded owing to a decrease in parasitic capacitance of the fluorescent lamp. <P>SOLUTION: A radiation point of light that a light emitting diode 3 emitting the light to irradiate a liquid crystal panel 1 emits toward the liquid crystal panel 1 from the opposite direction from the liquid crystal panel 1 about the fluorescent lamp 2 is provided at a position shifted from a conductive part 51 of a back member 5 provided opposite the fluorescent lamp 2 away from the fluorescent lamp 2. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

本発明は,例えば液晶テレビに代表される液晶表示装置に用いられるバックライト装置に関し,特に,蛍光管及び発光ダイオードの二種類の光源を備えてなるバックライト装置に関するものである。   The present invention relates to a backlight device used in a liquid crystal display device represented by, for example, a liquid crystal television, and more particularly to a backlight device including two types of light sources, a fluorescent tube and a light emitting diode.

一般に,液晶テレビに代表される液晶表示装置のバックライト装置には,R(赤),G(緑),B(青)を原色とする蛍光管が用いられている。この蛍光管には,赤色の波長光の発光強度が緑色や青色の波長光の発光強度に比べて小さいという特性があり,バックライト装置の発光色の色純度が十分ではなく,液晶表示装置における表示画像の色再現性に影響することが問題となっている。具体的には,液晶表示装置では,純粋な赤色が表示されにくい。そこで,従来から蛍光管及び赤色LED(発光ダイオード)の2種類の光源を併用して,蛍光管の赤色の波長光の発光強度を赤色LEDで補強することにより,発光色の色純度の向上が図られている(例えば特許文献1参照)。   In general, a backlight device of a liquid crystal display device typified by a liquid crystal television uses a fluorescent tube having R (red), G (green), and B (blue) as primary colors. This fluorescent tube has the characteristic that the emission intensity of the red wavelength light is smaller than the emission intensity of the green or blue wavelength light, and the color purity of the emission color of the backlight device is not sufficient. The problem is that it affects the color reproducibility of the display image. Specifically, it is difficult for a liquid crystal display device to display pure red. Therefore, conventionally, two types of light sources, a fluorescent tube and a red LED (light emitting diode), are used together, and the emission intensity of the red wavelength light of the fluorescent tube is reinforced with a red LED, thereby improving the color purity of the emitted color. It is illustrated (for example, refer to Patent Document 1).

ここに,図3(a)は従来の液晶表示装置Zの側断面図,図3(b)は従来の液晶表示装置Zの液晶パネル21及び拡散板26を取り外した状態を示す正面図である。
図3に示すように,従来の液晶表示装置Zは,画像を表示するための液晶パネル21と,上下方向に配列された複数の蛍光管22と,該蛍光管22各々の間に配列されて赤色の波長光を発光するLED23と,前記LED23が複数配列されて実装されたLED回路基板24と,前記LED回路基板24が固定された金属製の背面部材25と,前記蛍光管22及び前記LED23の光を拡散する拡散板26と,を備えて構成されている。
このように構成された液晶表示装置Zでは,図3(a)の一点鎖線内に示すように,前記蛍光管22各々の間に配置された前記LED23から赤色の波長光が発光されることにより,前記蛍光管22による赤色の波長光の発光強度が補強されて色純度が向上するため,該液晶表示装置Zにおける表示画像の色再現性の改善が図られる。
3A is a side sectional view of the conventional liquid crystal display device Z, and FIG. 3B is a front view showing a state in which the liquid crystal panel 21 and the diffusion plate 26 of the conventional liquid crystal display device Z are removed. .
As shown in FIG. 3, the conventional liquid crystal display device Z includes a liquid crystal panel 21 for displaying an image, a plurality of fluorescent tubes 22 arranged in the vertical direction, and a fluorescent tube 22 arranged between the fluorescent tubes 22. LED 23 for emitting red wavelength light, LED circuit board 24 on which a plurality of LEDs 23 are arranged and mounted, metal back member 25 to which LED circuit board 24 is fixed, fluorescent tube 22 and LED 23 And a diffusion plate 26 that diffuses the light.
In the liquid crystal display device Z configured as described above, red wavelength light is emitted from the LEDs 23 arranged between the fluorescent tubes 22 as shown in the dashed line in FIG. Since the emission intensity of the red wavelength light from the fluorescent tube 22 is reinforced and the color purity is improved, the color reproducibility of the display image in the liquid crystal display device Z is improved.

また,前記蛍光管22と前記背面部材25との間には,その離間距離に応じて変化する寄生容量が発生することが一般に知られている。この寄生容量は,前記蛍光管22内のプラズマと前記背面部材25とによってコンデンサが形成されることにより発生するものである。また,前記寄生容量は,前記蛍光管22と前記背面部材25との離間距離が短いほど大きくなり,離間距離が長いほど小さくなる。
ここで,前記寄生容量が大きくなりすぎると,前記蛍光管22からの漏れ電流が大きくなって該蛍光管22が均一に発光しないという問題が生じ,前記寄生容量が小さくなりすぎると,前記蛍光管22からの漏れ電流が小さくなって該蛍光管22の発光に係る電力効率が悪くなるという問題を生じる。そのため,前記蛍光管22と前記背面部材25との離間距離は,これらの問題が生じないように設計される。
特開2004−39876号公報
Further, it is generally known that a parasitic capacitance is generated between the fluorescent tube 22 and the back member 25, which varies depending on the separation distance. This parasitic capacitance is generated when a capacitor is formed by the plasma in the fluorescent tube 22 and the back member 25. The parasitic capacitance increases as the separation distance between the fluorescent tube 22 and the back member 25 decreases, and decreases as the separation distance increases.
Here, if the parasitic capacitance becomes too large, a leakage current from the fluorescent tube 22 becomes large, causing a problem that the fluorescent tube 22 does not emit light uniformly. If the parasitic capacitance becomes too small, the fluorescent tube This causes a problem that the leakage current from 22 becomes small and the power efficiency related to the light emission of the fluorescent tube 22 deteriorates. Therefore, the separation distance between the fluorescent tube 22 and the back member 25 is designed so that these problems do not occur.
JP 2004-39876 A

ところで,前記蛍光管22の発光強度の補強に用いられる前記LED23は指向性が強い光源であるため,前記蛍光管22の発光強度を補強することができる範囲が狭い。そのため,前記LED23の光が届く場所と届かない場所とで前記蛍光管22の発光強度が補強される程度が変化して色ムラが生じるおそれがある。この問題は,前記蛍光管22各々の間に短間隔で多数の前記LED23を設けることによって改善することができるが,多数の前記LED23を設けることはコスト高となり問題である。   By the way, since the LED 23 used to reinforce the light emission intensity of the fluorescent tube 22 is a light source having strong directivity, the range in which the light emission intensity of the fluorescent tube 22 can be reinforced is narrow. Therefore, there is a possibility that color unevenness may occur due to a change in the degree to which the light emission intensity of the fluorescent tube 22 is reinforced depending on where the light from the LED 23 reaches and where it does not reach. This problem can be improved by providing a large number of the LEDs 23 at short intervals between each of the fluorescent tubes 22, but providing a large number of the LEDs 23 is problematic because of high cost.

また,前記LED23を多数設けるのではなく,前記LED23を前記蛍光管22から十分に離間させた位置に設けて,該LED23の光を少しでも広がらせてから前記液晶パネル21に到達させることが考えられる。しかしながら,このような構成では,前述したように,前記蛍光管22と前記背面部材25との間に発生する寄生容量が小さくなって該蛍光管22の発光に係る電力効率が悪くなるという問題が生じる。
従って,本発明は前記事情に鑑みてなされたものであり,その目的とするところは,蛍光管の発光強度を補強して装置全体としての発光色の色ムラを防止するために必要な発光ダイオードの数を省減すると共に,前記蛍光管の寄生容量の減少に起因する電力効率の低下を防止することのできるバックライト装置及びこれを備えた液晶表示装置を提供することにある。
In addition, rather than providing a large number of the LEDs 23, it is conceivable that the LEDs 23 are provided at positions sufficiently separated from the fluorescent tube 22 to spread the light of the LEDs 23 even a little before reaching the liquid crystal panel 21. It is done. However, in such a configuration, as described above, the parasitic capacitance generated between the fluorescent tube 22 and the back member 25 is reduced, and the power efficiency related to the light emission of the fluorescent tube 22 is deteriorated. Arise.
Accordingly, the present invention has been made in view of the above circumstances, and an object of the present invention is to provide a light emitting diode necessary to reinforce the light emission intensity of the fluorescent tube and prevent color unevenness of the light emission color of the entire device. The present invention provides a backlight device and a liquid crystal display device including the backlight device that can reduce the number of light sources and prevent a reduction in power efficiency due to a decrease in parasitic capacitance of the fluorescent tube.

前記目的を達成するために本発明は,液晶パネルの背後から該液晶パネルに対して光を照射する蛍光管と,前記蛍光管に対して前記液晶パネルと反対の方向から前記液晶パネルに向けて照射される光を発光する発光ダイオードと,前記蛍光管に対して前記液晶パネルと反対の方向に所定量離間した位置に該蛍光管に相対して配置された導電性部材と,を備えてなるバックライト装置に適用されるものであって,前記発光ダイオードから発光されて前記液晶パネルに向けて照射される光の放射点が,前記導電性部材よりも前記蛍光管と離間する方向に突出した位置に設けられてなることを特徴とするバックライト装置として構成される。
このように,前記放射点だけを前記導電性部材よりも前記蛍光管と離間する方向に突出した位置に設けることにより,前記導電性部材と前記蛍光管との離間距離が大きくなりすぎることに起因して生じる電力効率の低下という問題を防止することができる。しかも,従来は前記導電性部材と同位置から前記液晶パネルに向けて放射されていた光が,本発明によれば前記蛍光管から前記導電性部材よりも離れた位置から前記液晶パネルに向けて放射されるため,その延びた距離を通過する分だけ光が広げられてから前記液晶パネルに到達する。これにより,前記発光ダイオードの数を増加させることなく前記蛍光管の発光強度をできる限り均一に補強して,前記液晶パネル上における色ムラを防止することが可能となる。
In order to achieve the above object, the present invention provides a fluorescent tube for irradiating light to the liquid crystal panel from behind the liquid crystal panel, and facing the liquid crystal panel from a direction opposite to the liquid crystal panel with respect to the fluorescent tube A light-emitting diode that emits irradiated light; and a conductive member disposed opposite to the fluorescent tube at a position spaced a predetermined amount in a direction opposite to the liquid crystal panel. The present invention is applied to a backlight device, and a radiation point of light emitted from the light emitting diode and applied to the liquid crystal panel protrudes in a direction away from the fluorescent tube rather than the conductive member. The backlight device is provided at a position.
Thus, by providing only the radiation point at a position protruding in a direction away from the fluorescent tube rather than the conductive member, the separation distance between the conductive member and the fluorescent tube is too large. Thus, the problem of a decrease in power efficiency that occurs can be prevented. In addition, according to the present invention, conventionally, light emitted from the same position as the conductive member toward the liquid crystal panel is directed from the position away from the fluorescent tube to the liquid crystal panel. Since the light is radiated, the light reaches the liquid crystal panel after being spread by an amount corresponding to the extended distance. Accordingly, it is possible to reinforce the light emission intensity of the fluorescent tube as uniformly as possible without increasing the number of light emitting diodes, and to prevent color unevenness on the liquid crystal panel.

ここに,前記放射点を前記導電性部材よりも前記蛍光管と離間する方向に突出した位置に設けるための具体的な構成としては,前記発光ダイオードを,前記導電性部材と,前記導電性部材から前記蛍光管と離間する方向に陥没した陥没部とを有する背面部材における前記陥没部の底部近傍に配置し,該底部近傍から前記液晶パネルに向けて光を放射させる構成が考えられる。
また,他の具体的手段としては,前記発光ダイオードが,前記導電性部材と,前記導電性部材から前記蛍光管と離間する方向に陥没した陥没部とを有する背面部材における前記陥没部内に向けて光を照射するように構成することも考えられる。これにより,前記発光ダイオードから発光された光が,前記陥没部内で反射して前記液晶パネルに向けて照射されることとなる。即ち,前記放射点が,前記導電性部材よりも前記蛍光管と離間する方向に突出した位置に擬似的に位置することとなる。
さらに,前記陥没部の内壁に光の反射率が高い部材(第2の光反射用部材)を設けることによって,前記発光ダイオードから発光された光を効率良く前記液晶パネルに対して放射することができる。
Here, as a specific configuration for providing the radiation point at a position protruding in a direction away from the fluorescent tube with respect to the conductive member, the light emitting diode includes the conductive member, and the conductive member. It is conceivable that the rear member having a recessed portion recessed in a direction away from the fluorescent tube is disposed in the vicinity of the bottom portion of the recessed portion, and light is emitted from the vicinity of the bottom portion toward the liquid crystal panel.
Further, as another specific means, the light emitting diode is directed toward the inside of the depressed portion in the back member having the conductive member and a depressed portion that is depressed from the conductive member in a direction away from the fluorescent tube. It may be configured to irradiate light. As a result, the light emitted from the light emitting diode is reflected in the depression and irradiated toward the liquid crystal panel. That is, the radiation point is located in a pseudo manner at a position protruding in a direction away from the fluorescent tube with respect to the conductive member.
Further, by providing a member (second light reflecting member) having a high light reflectance on the inner wall of the depressed portion, the light emitted from the light emitting diode can be efficiently emitted to the liquid crystal panel. it can.

また,前記発光ダイオードが実装される回路基板の前記蛍光管側の面に光の反射率が高い部材(第1の光反射用部材)を設けておけば,前記蛍光管から発光される光を前記液晶パネル側に効率良く反射させることができる。   Further, if a member having high light reflectance (first light reflecting member) is provided on the surface of the circuit board on which the light emitting diode is mounted, the light emitted from the fluorescent tube It can be efficiently reflected to the liquid crystal panel side.

ところで,前記陥没部の内壁は,前記発光ダイオードの光をできる限り広がらせた状態で前記液晶パネルに向けて放射させるため,底部から前記液晶パネル側に向けて拡開させておくことが望ましい。
さらに,前記陥没部の内壁を曲面とすることで,前記発光ダイオードの光がより広がった状態で前記液晶パネルに向けて放射される。
なお,本発明は,前述したように,前記発光ダイオードから発光されて前記液晶パネルに向けて照射される光の放射点が,前記導電性部材よりも前記蛍光管と離間する方向に突出した位置に設けられたバックライト装置を備えてなる液晶表示装置の発明として捉えても良い。
By the way, it is preferable that the inner wall of the depressed portion is expanded from the bottom toward the liquid crystal panel in order to radiate the light of the light emitting diode toward the liquid crystal panel in a state where the light is spread as much as possible.
Furthermore, by making the inner wall of the depressed portion a curved surface, the light of the light emitting diode is emitted toward the liquid crystal panel in a more spread state.
As described above, the present invention provides a position where the radiation point of light emitted from the light emitting diode and applied to the liquid crystal panel protrudes in a direction away from the fluorescent tube rather than the conductive member. The present invention may be regarded as an invention of a liquid crystal display device including a backlight device provided in the above.

本発明によれば,前記放射点だけを前記導電性部材よりも前記蛍光管と離間する方向に突出した位置に設けることにより,前記導電性部材と前記蛍光管との離間距離が大きくなりすぎることに起因して生じる電力効率の低下という問題を防止することができる。しかも,従来は前記導電性部材と同位置から前記液晶パネルに向けて放射されていた光が,本発明によれば前記蛍光管から前記導電性部材よりも離れた位置から前記液晶パネルに向けて放射されるため,その延びた距離を通過する分だけ光が広げられてから前記液晶パネルに到達する。これにより,前記発光ダイオードの数を増加させることなく前記蛍光管の発光強度をできる限り均一に補強して,前記液晶パネル上における色ムラを防止することが可能となる。   According to the present invention, the distance between the conductive member and the fluorescent tube is too large by providing only the radiation point at a position protruding in a direction away from the fluorescent tube than the conductive member. Therefore, it is possible to prevent the problem of reduction in power efficiency caused by the above. In addition, according to the present invention, conventionally, light emitted from the same position as the conductive member toward the liquid crystal panel is directed from the position away from the fluorescent tube to the liquid crystal panel. Since the light is radiated, the light reaches the liquid crystal panel after the light is spread by an amount corresponding to the extended distance. Accordingly, it is possible to reinforce the light emission intensity of the fluorescent tube as uniformly as possible without increasing the number of light emitting diodes, and to prevent color unevenness on the liquid crystal panel.

以下添付図面を参照しながら,本発明の実施の形態について説明し,本発明の理解に供する。尚,以下の実施の形態は,本発明を具体化した一例であって,本発明の技術的範囲を限定する性格のものではない。
ここに,図1(a)は本発明の実施の形態に係る液晶表示装置Xの概略構成を示す側断面図,図1(b)は前記液晶表示装置Xに設けられたバックライト装置Yの正面図である。
まず,図1を用いて,本発明の実施の形態に係る液晶表示装置Xの概略構成について説明する。
図1に示すように,前記液晶表示装置Xは,画像を表示するための液晶パネル1と,前記液晶パネル1の背後から該液晶パネル1に対して光を照射する複数の蛍光管2と,前記蛍光管2各々の間に該蛍光管2に対して前記液晶パネル1と反対の方向から前記液晶パネル1に向けて赤色の波長光を発光する複数の発光ダイオード3(以下,「LED3」という)と,前記LED3が複数配列されて実装されたLED回路基板4と,前記LED回路基板4が固定された背面部材5と,前記蛍光管2及び前記LED3の光を拡散して前記液晶パネルXに向けて出力する拡散板6と,を備えて概略構成されている。なお,ここでは,前記蛍光管2の赤色の波長光の発光強度を前記LED3で補強して赤色の色純度を高める手法を例にして説明するが,その他の色,例えば青色,又は緑色の色純度を高める場合にも本発明が適用できることは言うまでもない。
ここに,図1(b)に示すように,前記液晶表示装置Xの構成要素のうち,前記蛍光管2,前記LED3,前記LED回路基板4,前記背面部材5などが,当該液晶表示装置Xに設けられたバックライト装置Yを構成している。また,前記液晶表示装置Xは,図示する構成要素の他に一般的な液晶表示装置が備える構成要素,例えば制御回路や電源回路などを具備しているがここではその説明を省略する。
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings so that the present invention can be understood. The following embodiment is an example embodying the present invention, and does not limit the technical scope of the present invention.
1A is a side sectional view showing a schematic configuration of the liquid crystal display device X according to the embodiment of the present invention, and FIG. 1B is a diagram of a backlight device Y provided in the liquid crystal display device X. It is a front view.
First, a schematic configuration of the liquid crystal display device X according to the embodiment of the present invention will be described with reference to FIG.
As shown in FIG. 1, the liquid crystal display device X includes a liquid crystal panel 1 for displaying an image, a plurality of fluorescent tubes 2 for irradiating the liquid crystal panel 1 with light from behind the liquid crystal panel 1, Between each of the fluorescent tubes 2, a plurality of light emitting diodes 3 (hereinafter referred to as “LED 3”) that emit red wavelength light toward the liquid crystal panel 1 from a direction opposite to the liquid crystal panel 1 with respect to the fluorescent tube 2. ), A LED circuit board 4 on which a plurality of the LEDs 3 are arranged and mounted, a back member 5 to which the LED circuit board 4 is fixed, the fluorescent tube 2 and the light of the LED 3 are diffused to diffuse the liquid crystal panel X And a diffusing plate 6 for output toward the head. Here, a description will be given by taking as an example a method for enhancing the emission intensity of the red wavelength light of the fluorescent tube 2 by the LED 3 to increase the red color purity, but other colors such as blue or green Needless to say, the present invention can also be applied to increase the purity.
Here, as shown in FIG. 1B, among the components of the liquid crystal display device X, the fluorescent tube 2, the LED 3, the LED circuit board 4, the back member 5, etc. are connected to the liquid crystal display device X. The backlight device Y provided in is constructed. Further, the liquid crystal display device X includes components included in a general liquid crystal display device in addition to the illustrated components, for example, a control circuit and a power supply circuit, but the description thereof is omitted here.

前記背面部材5は,前記蛍光管2に対して前記液晶パネル1と反対の方向に所定量離間した位置に該蛍光管2に相対して配置された金属製の導電性部51(導電性部材の一例)と,前記導電性部51から前記蛍光管2と離間する方向に陥没した陥没部52とを有しており,図1(a)に示すように側断面が凹凸を形成している。なお,前記背面部材5は,前記導電性部51や前記陥没部52を別部品として組み合わせて構成してもよい。また,一体に形成したものであってもよい。また,前記背面部材5は,当該液晶表示装置Xの不図示の筐体と一体に,或いは別部材として構成される。   The back member 5 is made of a metal conductive portion 51 (conductive member) disposed opposite to the fluorescent tube 2 at a position spaced apart from the fluorescent tube 2 in a direction opposite to the liquid crystal panel 1 by a predetermined amount. 1) and a depressed portion 52 that is depressed in a direction away from the fluorescent tube 2 from the conductive portion 51, and the side cross section forms irregularities as shown in FIG. . The back member 5 may be configured by combining the conductive portion 51 and the depressed portion 52 as separate parts. Further, it may be integrally formed. Further, the back member 5 is configured integrally with the casing (not shown) of the liquid crystal display device X or as a separate member.

前記導電性部51は,該導電性部51の前記蛍光管2側の表面に設けられた不図示の反射シートにより該蛍光管2の光を反射すると共に,前記蛍光管2との間で寄生容量を発生させるものである。なお,前記導電性部51自体が金属製の導電性部材でなくとも,該導電性部51に設けられた前記反射シート(不図示)が導電性であればよい。
この寄生容量は,既に述べたように,前記導電性部51と前記蛍光管2との離間距離によって変化するものであって,該寄生容量の大小によって前記蛍光管2の均一な発光を阻害し,或いは電力効率を低下させるおそれがある。そのため,前記導電性部51は,前記蛍光管2を均一に発光させることが可能であって電力効率を低下させることのない距離だけ,前記蛍光管2から離間されている。
The conductive portion 51 reflects the light of the fluorescent tube 2 by a reflection sheet (not shown) provided on the surface of the conductive portion 51 on the fluorescent tube 2 side, and is parasitic between the conductive portion 51 and the fluorescent tube 2. It generates a capacity. In addition, even if the said electroconductive part 51 itself is not a metal electroconductive member, the said reflective sheet (not shown) provided in this electroconductive part 51 should just be electroconductive.
As described above, this parasitic capacitance changes depending on the distance between the conductive portion 51 and the fluorescent tube 2, and the size of the parasitic capacitance inhibits uniform light emission of the fluorescent tube 2. Or, there is a risk of reducing the power efficiency. Therefore, the conductive portion 51 is separated from the fluorescent tube 2 by a distance that allows the fluorescent tube 2 to emit light uniformly and does not reduce power efficiency.

前記陥没部52は,前記LED回路基板4を固定するための底部52aと,前記底部52aから前記液晶パネル1側に向けて拡開された内壁52bとを有している。また,図示しないが,前記内壁52bの内側には,光の反射率の高い反射シート(第2の光反射用部材の一例)が貼着されている。もちろん,前記内壁52b自体が光の反射率の高い部材から構成されるものであってもかまわない。また,前記内壁52bは,後述する実施例の内壁53(図2参照)のように,曲面であってもかまわない。   The depressed portion 52 has a bottom portion 52a for fixing the LED circuit board 4, and an inner wall 52b expanded from the bottom portion 52a toward the liquid crystal panel 1 side. Moreover, although not shown in figure, the reflection sheet (an example of the 2nd light reflection member) with a high reflectance of light is affixed inside the said inner wall 52b. Of course, the inner wall 52b itself may be composed of a member having high light reflectivity. Further, the inner wall 52b may be a curved surface like an inner wall 53 (see FIG. 2) of an embodiment described later.

ところで,前述したように,前記LED3が指向性の強い光源であるため,従来では,前記LED3を多数配設するか,或いは前記LED3を前記導電性部51と共に前記液晶パネル1から遠ざけることにより,当該液晶表示装置Xの装置全体としての発光色の色ムラの低減が図られていた。したがって,その一方で,前記LED3を多数配設することによりコストが高くなるという問題や前記導電性部51を前記液晶パネル1から遠ざけることにより前記寄生容量が減少して電力効率が低下するという問題を伴っていた。
しかし,本発明の実施の形態に係る前記液晶表示装置Xでは,前記導電性部51と前記蛍光管2との離間距離をL1,前記LED3と前記蛍光管2との離間距離をL2としたとき,L2>L1となるようにL1及びL2が前記背面部材5の断面凹凸形状により個別に設定されているため,前記した問題が共に改善される。以下,この点について詳説する。
By the way, as described above, since the LED 3 is a light source having a strong directivity, conventionally, a large number of the LEDs 3 are arranged, or the LED 3 is moved away from the liquid crystal panel 1 together with the conductive portion 51. The color unevenness of the light emission color as the whole apparatus of the liquid crystal display device X has been reduced. Therefore, on the other hand, the problem that the cost is increased by arranging a large number of the LEDs 3 and the problem that the parasitic capacitance is reduced and the power efficiency is lowered by moving the conductive portion 51 away from the liquid crystal panel 1. Was accompanied.
However, in the liquid crystal display device X according to the embodiment of the present invention, the distance between the conductive portion 51 and the fluorescent tube 2 is L1, and the distance between the LED 3 and the fluorescent tube 2 is L2. , L2> L1, L1 and L2 are individually set according to the cross-sectional concavo-convex shape of the back member 5, so that the above-mentioned problems are improved. This point will be described in detail below.

前記液晶表示装置Xでは,図1(a)に示すように,前記LED3は,前記LED回路基板4が前記背面部材5における前記陥没部52の底部52aに固定されることにより,該底部52aに配置されている。即ち,前記LED3から発光されて前記液晶パネル1に向けて照射される光の放射点が,前記導電性部51よりも前記蛍光管2と離間する方向に突出した位置(前記底部52a)に設けられることになる。
ここで,図1(a)の一点鎖線内に示した破線は,前記導電性部51と同じ位置に前記LED3が配設された場合に,該LED3から前記液晶パネル1側に向けて放射される光線を示している。一方,図1(a)の一点鎖線内に示した実線は,前記導電性部51よりも前記蛍光管2と離間する方向に突出した前記底部52aに前記LED3が配設された場合に,該LED3から前記液晶パネル1側に向けて放射される光線を示している。
図1(a)から明らかなように,本実施の形態に係る前記液晶表示装置Xのように前記LED3が前記導電性部51よりも前記蛍光管2と離間する方向に突出して設けられている場合の方が,前記LED3が前記導電性部51と同じ位置に設けられている場合よりも,前記LED3の光の通過距離が長いためその光が広がってから前記液晶パネル1に到達している。なお,前記陥没部52の内壁52aが拡開しているため,該光の広がりを阻害することもない。
したがって,前記LED3による前記蛍光管2の発光強度の補強にバラツキが減り,装置全体として発光される光の色ムラが防止される。そのため,前記LED3の数を省減することも可能である。
しかも,前述したように,前記背面部材5が,前記離間距離L1が,前記離間距離L2よりも小さくなるようにL1及びL2を個別に設計することのできる断面凹凸形状を有しているため,前記導電性部51と前記蛍光管2との間に所望の寄生容量が発生するように前記離間距離L1を設計するができ,該寄生容量が大きくなりすぎることに起因する電力効率の低下を防止することが可能である。また,前記背面部材5が図1(a)に示すように凹凸形状を有するため,平板状(図3参照)に形成されているよりも総面積が増加し,前記バックライト装置Y内の放熱効果も高まる。
In the liquid crystal display device X, as shown in FIG. 1A, the LED 3 is attached to the bottom 52a by fixing the LED circuit board 4 to the bottom 52a of the depressed portion 52 of the back member 5. Has been placed. That is, the radiation point of the light emitted from the LED 3 and emitted toward the liquid crystal panel 1 is provided at a position (the bottom portion 52a) protruding in a direction away from the fluorescent tube 2 from the conductive portion 51. Will be.
Here, the broken line shown in the alternate long and short dash line in FIG. 1A is emitted from the LED 3 toward the liquid crystal panel 1 when the LED 3 is disposed at the same position as the conductive portion 51. Shows the light rays. On the other hand, the solid line shown in the alternate long and short dash line in FIG. 1A shows the case where the LED 3 is disposed on the bottom portion 52a protruding in a direction away from the fluorescent tube 2 rather than the conductive portion 51. A light beam emitted from the LED 3 toward the liquid crystal panel 1 is shown.
As is clear from FIG. 1A, the LED 3 is provided so as to protrude in a direction away from the fluorescent tube 2 rather than the conductive portion 51 as in the liquid crystal display device X according to the present embodiment. In the case, the light passing through the LED 3 is longer than the case where the LED 3 is provided at the same position as the conductive portion 51, so that the light spreads before reaching the liquid crystal panel 1. . In addition, since the inner wall 52a of the depressed portion 52 is expanded, the spread of the light is not hindered.
Therefore, variation in the reinforcement of the light emission intensity of the fluorescent tube 2 by the LED 3 is reduced, and color unevenness of light emitted from the entire apparatus is prevented. Therefore, it is possible to reduce the number of the LEDs 3.
In addition, as described above, the back member 5 has a concavo-convex shape in which L1 and L2 can be individually designed so that the separation distance L1 is smaller than the separation distance L2. The separation distance L1 can be designed so that a desired parasitic capacitance is generated between the conductive portion 51 and the fluorescent tube 2, and a reduction in power efficiency due to the parasitic capacitance becoming too large is prevented. Is possible. Further, since the back member 5 has a concavo-convex shape as shown in FIG. 1A, the total area is increased as compared with the case where it is formed in a flat plate shape (see FIG. 3), and heat dissipation in the backlight device Y is performed. The effect also increases.

次に,図2を用いて,本発明の実施例に係る液晶表示装置X1について説明する。ここに,図2(a)は本発明の実施例に係る液晶表示装置X1の概略構成を示す側断面図,図2(b)は前記液晶表示装置X1に設けられたバックライト装置Y1の正面図である。なお,前記液晶表示装置X1において前記液晶表示装置X(図1参照)と同様の構成要素については同じ符号を付してその説明を省略する。
図2に示すように,本発明の実施例に係る液晶表示装置X1が,前記液晶表示装置Xと異なるところは,前記陥没部52に換えて曲面の内壁53aを有する陥没部53が前記背面部材5に設けられており,前記LED回路基板4が,前記LED3が前記陥没部53に向けて光を照射する方向に向いた状態で配設されている点にある。なお,前記内壁53aは,平面よりも光の拡散性の高い曲面であることが望ましいが平面であっても差し支えない。また,前記内壁53aの内側にも前記内壁52aと同様に光の反射率の高い反射シート(不図示,第2の光反射用部材の一例)が貼着されている。
また,前記LED回路基板4の背面,即ち前記液晶パネル1側の面には,光の反射率の高い反射シート4a(第1の光反射用部材の一例)が貼着されている。これにより,前記蛍光管2の光を,前記導電性部51だけでなく,前記反射シート4aにも反射させて前記液晶パネル1側に放射させることができる。なお,前記LED回路基板4は,不図示の螺子や係合部などによって前記背面部材5に取り付けられる。
Next, a liquid crystal display device X1 according to an embodiment of the present invention will be described with reference to FIG. 2A is a side sectional view showing a schematic configuration of the liquid crystal display device X1 according to the embodiment of the present invention, and FIG. 2B is a front view of the backlight device Y1 provided in the liquid crystal display device X1. FIG. In the liquid crystal display device X1, the same components as those of the liquid crystal display device X (see FIG. 1) are denoted by the same reference numerals, and description thereof is omitted.
As shown in FIG. 2, a liquid crystal display device X1 according to an embodiment of the present invention is different from the liquid crystal display device X in that a depressed portion 53 having a curved inner wall 53a is used instead of the depressed portion 52. 5, and the LED circuit board 4 is arranged in a state in which the LED 3 faces the direction in which the LED 3 emits light toward the depressed portion 53. The inner wall 53a is preferably a curved surface having a higher light diffusibility than a flat surface, but may be a flat surface. In addition, a reflective sheet (not shown, one example of a second light reflecting member) having a high light reflectivity is attached to the inner wall 53a as well as the inner wall 52a.
A reflective sheet 4a (an example of a first light reflecting member) having a high light reflectance is attached to the back surface of the LED circuit board 4, that is, the surface on the liquid crystal panel 1 side. Thereby, the light of the fluorescent tube 2 can be reflected not only to the conductive portion 51 but also to the reflection sheet 4a and radiated to the liquid crystal panel 1 side. The LED circuit board 4 is attached to the back member 5 by a screw or an engaging portion (not shown).

このように構成された前記液晶表示装置X1では,図2(a)の一点鎖線内に実線で示すように,前記LED3から発光された光が前記陥没部53の内壁53aで反射して前記液晶パネル1側に向けて照射される。このとき,前記液晶パネル1側に向けて照射される光は,前記蛍光管2と前記導電性部51との離間距離をL3,前記LED3と前記陥没部53の底部との距離をL4としたとき,前記蛍光管2からL3+2×L4だけ離れた位置Pから放射されたと擬似的に考えることができる。即ち,前記液晶パネル1に向けて照射される光の放射点が,前記導電性部51よりも前記蛍光管2と離間する方向に突出していると考えることができる。
そして,前記位置Pから放射された光が前記液晶パネル1に到達するまでの距離は,前記導電性部51の位置から直接前記液晶パネル1側に照射される光(図2(a)の一点鎖線の破線参照)に比べて十分に長く確保されているため,その光はより広げられた状態で前記拡散板6に到達することとなり,前記LED3の数を増加させずに該LED3による前記蛍光管2の発光強度の補強のバラツキを減らして装置全体として発光される光の色ムラを防止することできる。もちろん,前記液晶表示装置Xと同様に,前記背面部材5の断面凹凸形状により,前記導電性部51と前記蛍光管2との間に発生する寄生容量が大きくなりすぎることを防止することができるという構成も採用し得る。
In the liquid crystal display device X1 configured as described above, the light emitted from the LED 3 is reflected by the inner wall 53a of the depressed portion 53 as indicated by a solid line in the dashed line in FIG. Irradiated toward the panel 1 side. At this time, the light radiated toward the liquid crystal panel 1 is L3 as the distance between the fluorescent tube 2 and the conductive portion 51 and L4 as the distance between the LED 3 and the bottom of the depressed portion 53. At this time, it can be considered that the light is radiated from the position P away from the fluorescent tube 2 by L3 + 2 × L4. That is, it can be considered that the radiant point of light irradiated toward the liquid crystal panel 1 protrudes in a direction away from the fluorescent tube 2 from the conductive portion 51.
The distance until the light radiated from the position P reaches the liquid crystal panel 1 is the light irradiated directly on the liquid crystal panel 1 side from the position of the conductive portion 51 (one point in FIG. 2A). Compared to the broken line of the chain line), the light reaches the diffusion plate 6 in a more expanded state, and the fluorescence by the LED 3 is increased without increasing the number of the LEDs 3. It is possible to reduce unevenness in the reinforcement of the light emission intensity of the tube 2 and prevent color unevenness of the light emitted as the entire apparatus. Of course, as with the liquid crystal display device X, it is possible to prevent the parasitic capacitance generated between the conductive portion 51 and the fluorescent tube 2 from becoming excessively large due to the concavo-convex shape of the back member 5. A configuration such as this can also be adopted.

(a)は本発明の実施の形態に係る液晶表示装置の概略構成を示す側断面図,(b)は本発明の実施の形態に係るバックライト装置の正面図。(A) is a sectional side view which shows schematic structure of the liquid crystal display device which concerns on embodiment of this invention, (b) is a front view of the backlight apparatus which concerns on embodiment of this invention. (a)は本発明の実施例に係る液晶表示装置の概略構成を示す側断面図,(b)は本発明の実施例に係るバックライト装置の正面図。(A) is a side sectional view showing a schematic configuration of a liquid crystal display device according to an embodiment of the present invention, (b) is a front view of a backlight device according to an embodiment of the present invention. (a)は従来の液晶表示装置の側断面図,(b)は従来の液晶表示装置の液晶パネル及び拡散板を取り外した状態を示す正面図。(A) is a sectional side view of a conventional liquid crystal display device, and (b) is a front view showing a state in which a liquid crystal panel and a diffusion plate of the conventional liquid crystal display device are removed.

符号の説明Explanation of symbols

1…液晶パネル
2…蛍光管
3…LED(発光ダイオード)
4…LED回路基板
4a…反射シート
5…背面部材
6…拡散板
51…導電性部
52,53…陥没部
52a…底部
52b,53a…内壁
X,X1…液晶表示装置
Y,Y1…バックライト装置
DESCRIPTION OF SYMBOLS 1 ... Liquid crystal panel 2 ... Fluorescent tube 3 ... LED (light emitting diode)
4 ... LED circuit board 4a ... reflective sheet 5 ... back member 6 ... diffuser plate 51 ... conductive part 52, 53 ... recessed part 52a ... bottom part 52b, 53a ... inner wall X, X1 ... liquid crystal display device Y, Y1 ... backlight device

Claims (8)

液晶パネルの背後から該液晶パネルに対して光を照射する蛍光管と,
前記蛍光管に対して前記液晶パネルと反対の方向から前記液晶パネルに向けて照射される光を発光する発光ダイオードと,
前記蛍光管に対して前記液晶パネルと反対の方向に所定量離間した位置に該蛍光管に相対して配置された導電性部材と,
を備えてなるバックライト装置であって,
前記発光ダイオードから発光されて前記液晶パネルに向けて照射される光の放射点が,前記導電性部材よりも前記蛍光管と離間する方向に突出した位置に設けられてなることを特徴とするバックライト装置。
A fluorescent tube for irradiating the liquid crystal panel with light from behind the liquid crystal panel;
A light emitting diode that emits light emitted toward the liquid crystal panel from a direction opposite to the liquid crystal panel with respect to the fluorescent tube;
A conductive member disposed relative to the fluorescent tube at a position spaced a predetermined amount from the fluorescent tube in a direction opposite to the liquid crystal panel;
A backlight device comprising:
A back point in which a radiation point of light emitted from the light emitting diode and irradiated toward the liquid crystal panel is provided at a position protruding in a direction away from the fluorescent tube with respect to the conductive member. Light equipment.
前記導電性部材と,前記導電性部材から前記蛍光管と離間する方向に陥没した陥没部と,を有する背面部材を更に備えてなり,
前記発光ダイオードが,前記背面部材の陥没部の底部近傍に配置され,該底部近傍から前記液晶パネルに向けて光を放射してなる請求項1に記載のバックライト装置。
A back member having the conductive member and a recessed portion recessed in a direction away from the fluorescent tube from the conductive member;
2. The backlight device according to claim 1, wherein the light emitting diode is disposed in the vicinity of the bottom of the depressed portion of the back member, and emits light from the vicinity of the bottom toward the liquid crystal panel.
前記導電性部材と,前記導電性部材から前記蛍光管と離間する方向に陥没した陥没部と,を有する背面部材を更に備えてなり,
前記発光ダイオードが,前記陥没部内に向けて光を照射してなる請求項1に記載のバックライト装置。
A back member having the conductive member and a recessed portion recessed in a direction away from the fluorescent tube from the conductive member;
The backlight device according to claim 1, wherein the light emitting diode is irradiated with light toward the recessed portion.
前記発光ダイオードが実装される回路基板を更に備えてなり,
前記回路基板の前記蛍光管側の面に光の反射率が高い第1の光反射用部材が設けられてなる請求項3に記載のバックライト装置。
A circuit board on which the light emitting diode is mounted;
The backlight device according to claim 3, wherein a first light reflecting member having a high light reflectance is provided on a surface of the circuit board on the fluorescent tube side.
前記陥没部の内壁に光の反射率が高い第2の光反射用部材が設けられてなる請求項2〜4のいずれかに記載のバックライト装置。   The backlight device according to claim 2, wherein a second light reflecting member having a high light reflectance is provided on an inner wall of the depressed portion. 前記陥没部の内壁が,底部から前記液晶パネル側に向けて拡開してなる請求項2〜5のいずれかに記載のバックライト装置。   The backlight device according to claim 2, wherein an inner wall of the depressed portion is expanded from the bottom toward the liquid crystal panel. 前記陥没部の内壁が曲面である請求項2〜6のいずれかに記載のバックライト装置。   The backlight device according to claim 2, wherein an inner wall of the depressed portion is a curved surface. 請求項1〜7のいずれかに記載のバックライト装置を備えてなる液晶表示装置。   A liquid crystal display device comprising the backlight device according to claim 1.
JP2005317175A 2005-10-31 2005-10-31 Backlight device, and liquid crystal display device Pending JP2007121927A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2008299170A (en) * 2007-06-01 2008-12-11 Hitachi Ltd Video display device and backlight unit used for the same
CN106855664A (en) * 2015-12-09 2017-06-16 天津三星电子有限公司 A kind of LCDs

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JPH05224200A (en) * 1991-11-01 1993-09-03 Litton Syst Canada Ltd Night vision back lighting apparatus for liquid crystal display
JP2002258281A (en) * 2001-03-01 2002-09-11 Furuno Electric Co Ltd Liquid crystal display, luminance adjusting device and display device
JP2003140110A (en) * 2001-08-20 2003-05-14 Hitachi Ltd Liquid crystal display device and its drive circuit
JP2003330424A (en) * 2002-05-10 2003-11-19 Hitachi Ltd Liquid crystal display device
JP2004139876A (en) * 2002-10-18 2004-05-13 Sharp Corp Lighting device, backlight device, and liquid crystal display device

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Publication number Priority date Publication date Assignee Title
JPH05224200A (en) * 1991-11-01 1993-09-03 Litton Syst Canada Ltd Night vision back lighting apparatus for liquid crystal display
JP2002258281A (en) * 2001-03-01 2002-09-11 Furuno Electric Co Ltd Liquid crystal display, luminance adjusting device and display device
JP2003140110A (en) * 2001-08-20 2003-05-14 Hitachi Ltd Liquid crystal display device and its drive circuit
JP2003330424A (en) * 2002-05-10 2003-11-19 Hitachi Ltd Liquid crystal display device
JP2004139876A (en) * 2002-10-18 2004-05-13 Sharp Corp Lighting device, backlight device, and liquid crystal display device

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2008299170A (en) * 2007-06-01 2008-12-11 Hitachi Ltd Video display device and backlight unit used for the same
CN106855664A (en) * 2015-12-09 2017-06-16 天津三星电子有限公司 A kind of LCDs

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