JP2001194666A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a picture display with high brightness and high quality by suppressing lowering of light emitting efficiency of a linear light source to prevent display quality from deteriorating and solving shortage of brightness of a backlight comprising the plural arrayed linear light sources in the periphery of a liquid crystal panel. SOLUTION: The liquid crystal display device is provided with the backlight, comprising the plural arrayed linear light sources CFL having electrode parts ELD on the edge parts, and arranged on the rear surface of a liquid crystal panel via an optical compensation sheet. The backlight has a lower frame FLM-D formed with a metal plate and is provided with a heat radiating member MP surrounding the electrode parts ELD of the linear light sources CFL making intervene an insulation cushion material GB and thermally connected to the lower frame FLM-D composed of a metal material. Also the edge parts of the plural arrayed linear light sources CFL are arranged so as to come near to the liquid crystal panel side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device which suppresses a decrease in luminance due to heat generation of a light source for illuminating the liquid crystal panel. The present invention relates to a liquid crystal display device in which the lack of brightness in the above is eliminated and the brightness becomes uniform throughout the liquid crystal panel.

[0002]

2. Description of the Related Art A high-definition, thin, light-weight, high-definition computer, display monitor, or television receiver is used.
A liquid crystal display device is widely used as a display device capable of color display.

[0003] This type of liquid crystal display device uses a simple matrix type liquid crystal panel using a liquid crystal panel in which a liquid crystal layer is sandwiched between a pair of substrates on which parallel electrodes formed so as to intersect each other on respective inner surfaces. An active matrix type liquid crystal display device using a liquid crystal panel having a switching element for selecting a pixel in one of a pair of substrates is known.

An active matrix type liquid crystal panel, as represented by a twisted nematic (TN) mode, uses a liquid crystal panel in which an electrode group for pixel selection is formed on a pair of upper and lower substrates, a so-called vertical electric field mode ( A so-called lateral electric field method (generally referred to as an IPS method) using a liquid crystal panel in which an electrode group for pixel selection is formed only on one of a pair of upper and lower substrates, and a TN method.
There is.

The former TN mode liquid crystal panel is composed of a pair (a first substrate (lower substrate) and a second substrate (upper substrate)).
The liquid crystal is twisted and oriented, for example, by 90 ° in the substrate, and the absorption axis directions are arranged in crossed Nicols on the outer surfaces of the upper and lower substrates of the liquid crystal panel, and the absorption axes on the incident side are parallel or intersected with the rubbing direction. And two polarizing plates.

In such a TN type active matrix type liquid crystal panel, when no voltage is applied, incident light becomes linearly polarized light on the incident side polarizing plate, and this linearly polarized light propagates along the twist of the liquid crystal layer, and the emitting side polarizing plate. When the transmission axis of coincides with the azimuth angle of the linearly polarized light, all of the linearly polarized light is emitted and white display is performed (a so-called normally open mode).

When a voltage is applied, the direction (director) of a unit vector indicating the average alignment direction of the liquid crystal molecular axes constituting the liquid crystal layer is oriented in a direction perpendicular to the substrate surface, and the azimuth of the incident side linearly polarized light. Since the angle does not change, it coincides with the absorption axis of the exit-side polarizing plate, so that black display is performed. (See "Basics and Applications of Liquid Crystals" published by the Industrial Research Council in 1991).

On the other hand, an electrode group for pixel selection and an electrode wiring group are formed only on one of a pair of substrates, and a voltage is applied between adjacent electrodes (between a pixel electrode and a counter electrode) on the substrate by applying a voltage. In an IPS type liquid crystal panel that switches layers in a direction parallel to the substrate surface, a polarizing plate is arranged so as to display black when no voltage is applied (a so-called normally closed mode).

In the initial state, the liquid crystal layer of the IPS mode liquid crystal panel has a homogeneous orientation parallel to the substrate surface, and has a plane parallel to the substrate, and the director of the liquid crystal layer is parallel or slightly parallel to the electrode wiring direction when no voltage is applied. With the voltage applied, the direction of the director of the liquid crystal layer shifts in the direction perpendicular to the electrode wiring direction with the application of voltage, and the director direction of the liquid crystal layer is compared to the director direction when no voltage is applied. The liquid crystal layer at the time of applying the voltage,
The azimuth of the polarized light is rotated by 90 ° like a half-wave plate, and the transmission axis of the exit-side deflecting plate and the azimuth of the polarized light coincide with each other, and white display is performed.

The IPS mode liquid crystal panel has a feature that a change in hue and contrast is small even at a viewing angle, and a wide viewing angle is achieved (Japanese Patent Laid-Open No. 5-5052).
No. 47).

[0011] A color filter system is mainly used in a full-color liquid crystal display device using the above-described various liquid crystal panels. In this method, a pixel corresponding to one dot of color display is divided into three, and a color filter corresponding to each of three primary colors, for example, red (R), green (G), and blue (B) is arranged in each unit pixel. This is achieved by doing so.

[0012] In such a liquid crystal display device, it is necessary to provide external illumination in order to visualize an electronic image formed on the liquid crystal panel.

As the illuminating means, there are a passive illuminating method using ambient light and an active illuminating method in which a light source such as a cold-cathode fluorescent lamp is installed on the back or front side of the liquid crystal panel.

Among the active illumination methods, a method of arranging a light source on the surface side of a liquid crystal panel (generally called a front light method) is often adopted in portable information equipment.
On the other hand, in a liquid crystal display device having a relatively large size such as a personal computer or a display monitor, it is common to arrange a light source on the back of the liquid crystal panel (this is generally called a backlight).

In information equipment such as a notebook personal computer, which is required to be thin, a linear light source such as a cold cathode fluorescent lamp (hereinafter, also referred to as CFL) is arranged at the edge of a transparent plate (referred to as a light guide plate). Make up the light.

However, with the recent increase in the size of the liquid crystal panel of a liquid crystal display device used for a display monitor or a television receiver compatible with moving images, it is necessary to obtain sufficient screen brightness (brightness) and to make the screen brightness uniform. Multiple C
A high-brightness backlight in which the FL is arranged on the back surface of the liquid crystal panel has been adopted. This is generally called a direct backlight.

FIG. 22 is an exploded perspective view for explaining an example of a conventional direct type backlight. In this backlight, a plurality of CFLs are arranged on the upper surface of a lower frame FLM-D generally made of a metal material so that the longitudinal directions thereof are parallel to each other.
An upper frame FLM-U is put on this, and the both are united with a nail NL, and a resin mold MLD-L is formed on both sides (left and right).
The upper frame FLM-U and the lower frame FLM-D are sandwiched and integrated by the left mold and the MLD-R (right mold). In this case, the surface on the CFL side of the lower frame FLM-D has the function of a reflector. However, although not shown, another member such as a sheet having a light reflecting function is interposed between the lower frame FLM-D and the CFL, or a chevron is formed on the entire surface of the lower frame FLM-D along the longitudinal direction of the CFL. Of the lower frame FLM-D having the reflection sheet or the reflection sheet or the reflection sheet.
There is also a configuration in which a chevron-shaped reflecting plate is arranged in a portion excluding the lower part of L.

A light diffusion plate SCT (hereinafter simply referred to as a diffusion plate) and a diffusion sheet S are placed on the upper frame FLM-U.
Optical compensation sheet O composed of CTS, prism sheet, etc.
The direct-type backlight is constituted by laminating PS.
Some do not have the diffusion sheet SCTS. A liquid crystal panel (not shown, described later) is provided above the backlight.
Is mounted, and a power supply for driving the CFL, other necessary circuits, and structural members are mounted.

The direct-type backlight is not limited to the above-described configuration, and various assembled shapes are known.
Lower frame FLM-D functioning as a fixing member for L
Is required.

[0020]

FIG. 23 is a schematic sectional view for explaining an example of arrangement of linear light sources in a direct type backlight using a plurality of linear light sources. In the conventional backlight described with reference to FIG. 22, as shown in FIG. 23, the plurality of linear light sources CFL are arranged on the inner surface of the lower frame FLM-D on a line LL equidistant from the inner surface. I have. Therefore, as illustrated, in the end region of the diffusion plate SCT, the distance d from the linear light source CFL-E at the end is larger than the distance from the linear light source CFL in the central region. As a result, there is a problem in that the amount of illumination light is less at the periphery of the liquid crystal panel PNL than at the central region, the luminance around the screen is reduced, and the display quality is degraded.

In this type of backlight, the CFL is generally held in the lower frame FLM-D as follows. That is, FIG. 24 is a schematic diagram of a main part showing an example of the CFL support structure of the backlight shown in FIG. In the figure, PBR is a frame member for fixing the CFL, PXH is a CFL fixing recess, and GB is an insulating cushion material such as a rubber material or a urethane foam material.

The CFL covers the electrode portions at both ends thereof with an insulating cushion material GB, and pushes and holds the insulating cushion material GB into the CFL fixing recess PXH of the frame member PBR. The frame member PBR is fixed to the lower frame FLM-D by an appropriate means.

However, as the applied current value and the number of CFLs increase in order to increase the brightness of the screen of the liquid crystal panel, the calorific value of the electrode portion in particular increases, and the efficiency of the CFL decreases. Further, in the CFL fixing structure as shown in the figure, the heat generation of the electrode portion is hardly dissipated, and the heat is collected in the backlight,
This causes a problem that the properties of the liquid crystal layer are changed over the liquid crystal layer of the liquid crystal panel, thereby deteriorating the display quality.

Further, the diffuser plate used in the conventional direct-type backlight has irregularities for diffusing light on both surfaces thereof (the surface facing the linear light source and the surface opposite to the linear light source). ing.

FIG. 25 is a schematic cross-sectional view of a diffusion plate used in a conventional direct-type backlight. The light-entering surface (surface facing the linear light source) SF-1 and the light-emitting surface (line) of the diffusion plate SCT are shown in FIG. The uneven surface DB is formed on both surfaces SF-E). The irregularities DB are formed by subjecting the surface of a transparent plate such as an acrylic resin plate to a foaming treatment (surface foaming).

The scattered light is scattered by the irregularities DB light emitting surface SF-E of the output light L _E Toko emitted from the light exit surface SF-E L _S
Is illumination light for illuminating the liquid crystal panel. But,
In such a diffuser plate having unevenness on both sides, L
Re-reflected from the linear light source shown, or a reflection plate, a portion of the incident light L incident reflected from the reflective sheet in the incident surface SF-1 reflected light L _R, the scattered light L _S becomes, by the reflector in reflected light L _R is recycled is less.

FIG. 26 shows a lower frame FL having a reflection function.
FIG. 26 is a schematic explanatory view of a light utilization mode when a direct-type backlight having a mountain-shaped reflecting plate REF in the MD is combined with the diffusion plate having unevenness on both sides shown in FIG. 25.

The reflected light L at the light incident surface SF-1 of the diffusion plate SCT
_R, Scattered light L_SAnd mainly reflected light L_RIs the reflector R
The light is reflected again by the EF in the direction of the diffusion plate SCT, and
Of the incident light L
Scattered light L at the light incident surface SF-1 _SAnd with the reflector REF
Reflected light L that is re-reflected_RIs reduced by that amount. That
Control the brightness distribution of the illumination light with a reflector
It is difficult to obtain luminance uniformity on the screen.

This has been one obstacle to improving the light use efficiency in the direct type backlight using the linear light source.

An object of the present invention is to solve the above-mentioned problems of the prior art, to suppress a decrease in the luminous efficiency of the CFL and to prevent the display quality from deteriorating. In order to improve the light utilization of the linear light source and the uniformity of the luminance distribution by controlling the light from the linear light source by the reflector and the reflected light from the diffuser, high brightness and high quality An object of the present invention is to provide a liquid crystal display device capable of obtaining an image display.

[0031]

In order to achieve the above object, the present invention is directed to a lower frame made of a metal material, wherein an insulating cushion material covering an electrode portion of a linear light source is surrounded by a heat radiating member such as a metal plate. And thermally coupled. In addition, among the plurality of linear light sources, the linear light source located at the end of the lower frame is arranged close to the liquid crystal panel side. Further, the luminance distribution of the illumination light of the liquid crystal panel is controlled by making the surface of the diffusion plate facing the linear light source a reflection surface. Hereinafter, a typical configuration of the present invention will be described. (1) A liquid crystal display device having a backlight in which a plurality of linear light sources each having an electrode portion at an end are arranged and installed on the back of a liquid crystal panel via an optical compensation sheet, wherein the backlight is made of metal. A heat dissipating member is provided which has a lower frame formed of a plate and which is thermally coupled to the lower frame made of a metal material surrounding an electrode portion of the linear light source with an insulating cushion material interposed therebetween.

Thus, the heat generated in the electrode portion of the linear light source is dissipated from the heat radiating member and is conducted to the lower frame, so that the heat can be dissipated efficiently. (2): The heat radiation member in (1) is formed by cutting and raising a part of the lower frame.

The heat dissipating member is preferably a metal plate having a large thermal conductivity. The heat dissipating member may be a separate member from the lower frame, or may be formed by cutting a part of the lower frame. This is cost-effective. (3): A liquid crystal display device provided with a backlight in which a plurality of linear light sources each having an electrode portion at an end portion are arranged and installed on the back surface of a liquid crystal panel via an optical compensation sheet. The longitudinal directions of the plurality of linear light sources are arranged in parallel with the back surface of the liquid crystal panel, and the linear light sources located at both ends of the plurality of linear light sources are arranged close to the liquid crystal panel side.

According to this configuration, the density of the illuminating light to the edge of the liquid crystal panel increases, and uniform luminance can be obtained over the entire screen. (4): The backlight according to (3) is formed on a lower frame made of a metal material, a plurality of linear light sources arranged in parallel with the lower frame, and an upper frame for holding the plurality of linear light sources together with the lower frame. And an optical compensation sheet laminated on the upper frame. (5): A configuration in which the electrode portion of the linear light source in (3) or (4) includes a heat radiating member thermally coupled to the lower frame made of a metal material surrounded by an insulating cushion material. did.

Thus, as in (1), the heat generated by the electrode portion of the linear light source is radiated from the heat radiating member, and is conducted to the lower frame, so that the heat can be efficiently radiated. (6): The heat radiation member in (5) was formed by cutting and raising a part of the lower frame.

As in the case of (2), the heat radiating member is preferably a metal plate having a large thermal conductivity, and may be a member separate from the lower frame or a part of the lower frame cut out.
It is preferable in terms of cost to cut out and form a part of the lower frame. (7): The optical compensatory sheet in (4), (5), or (6) further includes a diffusion plate located immediately above the plurality of linear light sources, and a diffusion plate is provided on a back surface of the diffusion plate with respect to the plurality of linear light sources. A surface having irregularities and facing the plurality of linear light sources was a flat surface.

With this configuration, it is possible to obtain a uniform and high-brightness illumination height distribution in which reflected light control by adjusting the reflection characteristics of the reflector for reusing the reflected light from the diffuser is not easy. (8): A peak is provided between the plurality of linear light sources on the side opposite to the diffusion plate with respect to the plurality of linear light sources in (7), and as the distance from the top to the diffusion plate increases, And a mountain-shaped reflector having a curved surface as gradually approaching the linear light source.

In addition to the effect of the above configuration (7), the reflected light from the diffuser can be used efficiently together with the light from the linear light source, and the luminance distribution is controlled so that the light is directed toward the diffuser so that the screen of the liquid crystal panel can be used. Can be uniformly illuminated.

The present invention is not limited to the above configuration, and various modifications can be made without departing from the technical idea of the present invention. Other objects and configurations of the present invention will become apparent from the description of the embodiments described below.

[0040]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a side view of a main part showing a holding structure of a linear light source constituting a backlight for explaining a first embodiment of a liquid crystal display device according to the present invention, and FIG. FIG. 3 is a front view of FIG. 2 viewed from the direction of arrow B. FIG. In each figure, FLM-D is the lower frame, CF
L denotes a cold cathode fluorescent lamp as a linear light source, ELD denotes an electrode part thereof, ESP denotes a power supply line, GB denotes a rubber cushion as an insulating cushion material, and MP denotes a radiator plate.

In this embodiment, a part of the lower frame FLM-D is cut and raised as shown by an arrow C in FIG.
P is formed, and this is used as the electrode part ELD of the cold cathode fluorescent lamp CFL.
The cold cathode fluorescent lamp CFL is held and fixed so as to surround the rubber cushion GB put around the CFL.

According to this embodiment, the heat generated in the vicinity of the electrode portion of the cold cathode fluorescent lamp CFL is radiated from the heat radiating plate MP and is also conducted and radiated to the lower frame FLM-D to reduce the luminous efficiency of the cold cathode fluorescent lamp CFL. Reduction is prevented. Therefore, a decrease in luminance is suppressed and a bright image is formed on the screen of the liquid crystal panel.

FIG. 4 is a side view of a main part showing a holding structure of a linear light source constituting a backlight for explaining a second embodiment of the liquid crystal display device according to the present invention, and FIG. 6 is a front view of FIG. 5 viewed from the direction of arrow B. FIG. In each figure, it corresponds to the same functional part shown by the same reference numeral in FIGS.

In the present embodiment, a part of the lower frame FLM-D is cut and raised as shown by an arrow C in FIG. 6, and this is curved so as to be concave toward the cold cathode fluorescent lamp CFL, thereby forming a heat sink M.
P was formed.

According to this embodiment, the cold cathode fluorescent lamp CFL
The heat generated in the vicinity of the electrode part is dissipated from the radiator plate MP and is also conducted to the lower frame FLM-D and dissipated, thereby preventing the luminous efficiency of the cold cathode fluorescent lamp CFL from lowering. Therefore, a decrease in luminance is suppressed and a bright image is formed on the screen of the liquid crystal panel.

FIG. 7 is a side view showing a main part of a structure for holding a linear light source constituting a backlight for explaining a third embodiment of the liquid crystal display device according to the present invention. FIG. FIG. 9 is a front view of FIG. 8 viewed from the direction of arrow B. FIG. In each figure, PRJ is a bent portion, and FIGS.
1 to 3 correspond to the same functional parts.

In the present embodiment, a part of the lower frame FLM-D is cut and raised as shown by an arrow C in FIG. 9, and this is curved so as to be concave toward the cold cathode fluorescent lamp CFL, thereby forming a heat sink M.
A bent portion PRJ is formed by forming P and inverting a tip portion thereof.

According to this embodiment, the cold cathode fluorescent lamp CFL
The heat generated in the vicinity of the electrode part is dissipated from the radiator plate MP and is also conducted to the lower frame FLM-D and dissipated, thereby preventing the luminous efficiency of the cold cathode fluorescent lamp CFL from lowering. A bent portion PR obtained by inverting a tip portion of a curved heat sink MP.
J facilitates insertion of the rubber cushion GB covering the electrode portion of the cold cathode fluorescent lamp CFL. As a result, similarly to the above embodiments, a decrease in luminance is suppressed, and a bright image is formed on the screen of the liquid crystal panel.

FIG. 10 shows a fourth embodiment of the liquid crystal display device according to the present invention.
FIG. 2 is a side view of a main part showing a holding structure of a linear light source constituting a backlight for explaining the embodiment. In this embodiment, the heat radiating plate MP is formed of a metal plate separate from the lower frame FLM-D, and is fixed to the lower frame FLM-D by welding, screwing, or fitting.

The shape of the heat radiating plate MP may be the same as that of each of the embodiments described with reference to FIGS. 1 to 9, and the effects are the same as those of the corresponding embodiments.

According to this embodiment, the cold cathode fluorescent lamp CFL
The heat generated in the vicinity of the electrode part is dissipated from the radiator plate MP and is also conducted to the lower frame FLM-D and dissipated, thereby preventing the luminous efficiency of the cold cathode fluorescent lamp CFL from lowering. As a result, similarly to the above embodiments, a decrease in luminance is suppressed, and a bright image is formed on the screen of the liquid crystal panel.

FIG. 11 shows a fifth embodiment of the liquid crystal display device according to the present invention.
FIG. 2 is an exploded perspective view for explaining the configuration of the entire backlight for explaining the embodiment. In the figure, the same reference numerals as those in FIG. 22 correspond to the same functional parts. Since the schematic structure of this backlight is the same as that shown in FIG. 22, repeated description is minimized.

The lower frame FLM- generally made of a metal material
A plurality of CFLs are arranged on the upper surface of D so that their longitudinal directions are parallel. The surface on the CFL side of the lower frame FLM-D has a function of a reflector. This lower frame FL
A separate member such as a sheet having a reflection function or a chevron-shaped reflector may be interposed or installed between the MD and the CFL.

In this embodiment, among the plurality of linear light sources CFL disposed on the upper surface of the lower frame FLM-D, the mounting positions of the linear light sources CFL-E located at both ends are changed to the arrangement surface of the other linear light sources CFL. It is closer to the diffusion plate SCT side, that is, the liquid crystal panel side than the level by the distance H.

FIG. 12 illustrates an example of the arrangement of linear light sources in a direct-type backlight using a plurality of linear light sources.
FIG. 4 is a schematic sectional view similar to FIG. In the drawing, LL is an arrangement surface level of the linear light sources CFL other than the linear light sources CFL-E located at both ends. The linear light sources CFL-E located at both ends are diffused by a dimension H with respect to the arrangement plane level LL by a dimension H.
It is moved to the T side. The dimension H is determined by the size of the backlight, the number of linear light sources and the amount of light emission, and the diffusion plate SCT.
Is determined at the design stage in consideration of the distance D to the periphery of the device.

As shown in FIG. 11, the lower frame FL corresponding to the linear light sources CFL-E located at both ends.
The upper surface of the MD may be inclined in the direction of the liquid crystal panel, so that the efficiency of using the light emitted by the linear light source CFL-E can be improved.

According to this embodiment, the light emitted from the linear light source irradiating the rear surface of the diffusion plate SCT becomes substantially uniform on the front surface.
The liquid crystal panel installed above the diffusion plate can display an image with uniform luminance over the entire surface.

FIG. 13 illustrates an example of a specific structure of the backlight of the liquid crystal display device according to the present invention.
FIG. 14 is a cross-sectional view of a main part along D, and FIG.
FIG. 2 is a cross-sectional view of a main part along line EE of FIG. This backlight has a plurality of linear light sources CF on the inner surface of the lower frame FLM.
After fixing L in any of the structures of the above-described embodiment, the lower frame FLM-D and the upper frame FLM-U are attached to each other, and both are fixed at predetermined positions with the claws NL. -Integrally fixed with -R.

Then, on the upper surface of the upper frame FLM-U, a diffusion plate SCT and an optical compensation sheet OPS including a diffusion sheet SCTS and a prism sheet PRS are placed, and screws B are set.
It is fixed at T.

As described above, among the linear light sources CFL installed on the inner surface of the lower frame FLM, the linear light sources CFL-E located at both ends are the diffusion plates by the distance H from the arrangement level of the other linear light sources CFL. It is shifted to the SCT side.

In FIG. 14, a corrugated reflector REF is provided on the inner surface of the lower frame FLM, and the use efficiency of light emitted from the linear light source is improved by the reflector REF.

FIG. 15 is an exploded perspective view showing a more specific configuration example of the direct type backlight according to the present invention. FIG.
11 shows components that are also mounted on the direct-type backlight structure shown in FIGS. 11 and 22. Linear light source C
One end of a power supply line (cable) ESP is attached to each end of the FL, and is covered with a rubber cushion (rubber bush) GB fitted to each power supply line.

A connector CO is connected to the other end of the power supply line ESP.
N is attached. The connector CON has a structure for receiving a pair of power supply lines ESP adjacent to each other, but the power supply lines are separated inside the connector.

The connector CON arranged on the right side of FIG. 15 is a lower frame FLM- made of a metal material such as aluminum.
D is connected to an inverter circuit INV mounted on a circuit board mounted on the lower surface of D. In FIG. 15, the circuit board on which the inverter circuit is mounted is indicated by INV, but the inverter circuit itself will be described below as INV.

An inverter circuit INV is individually provided for each of the linear light sources CFL, and this circuit and the linear light source CF are provided.
The end (electrode) on the high voltage application side of L (also called the hot side and located on the right side in FIG. 2) is connected so that the wiring length between them does not vary for each linear light source.

The linear light source CFL is supplied from the inverter circuit INV.
The voltage supplied to the (cold-cathode tube) receives a loss according to the length of the power supply line ESP, and a variation in luminance occurs between the plurality of linear light sources CFL. Making the wiring length of each power supply line ESP uniform is effective in preventing image deterioration of the liquid crystal panel due to this luminance variation, and a plurality of inverter circuits INV are arranged in parallel on the right side of the lower frame FLM-D. The layout to be arranged is one of the means.

An insulating sheet I is provided between the lower surface of the lower frame FLM-D and the circuit board on which the inverter circuit INV is mounted.
NS is arranged, and the inverter circuit INV (circuit board) is attached to the cover ICOV and the insulating sheet INS is provided.
To the lower frame FLM-D.

The lower frame F is provided on the lower surface of the insulating sheet INS.
A connector board CSUB extending along the left side of the LM-D is provided. In FIG. 15, the connector CON that receives the power supply line ESP connected to the left side of each linear light source CFL is connected to the terminal of the connector board CSUB. Connector board CS
One terminal of a connector CON formed at both ends of the power supply line ESP is connected to another terminal of the UB, and the other terminal is connected to a low voltage side (reference potential side) terminal of the inverter circuit INV. In such a connection, each linear light source CF in FIG.
Left electrode of L (also called low voltage side, Cold side)
Is applied with a reference potential.

The above configuration is common to the direct type backlights shown in FIGS. 11 and 22, but the backlight shown in FIG. 15 has the following structural features. Its main features are as follows.

That is, the diffusion plate SCT and the diffusion sheet SC
The upper sheet FLM made of a metal, which is preferably made of aluminum, which is an optical sheet made of a laminate of TS and a prism sheet PRS.
-U and a right mold MLD-R and a left mold MLD-L made of a synthetic resin or the like.

In such a structure, an unexpected mechanical shock or thermal shock caused by the upper surface of the upper frame FLM-U made of metal coming into contact with the lower surface of the liquid crystal panel, that is, the main surface of the substrate made of glass or the like, is not affected. Joins the bottom of the LCD panel,
The substrate may be damaged. To prevent this, a rubber spacer GS is provided on the upper surface of the upper frame FLM-U along the opening of the upper frame FLM-U.

Each of the diffusion plate SCT, the diffusion sheet SCTS, and the prism sheet PRS constituting the optical sheet is obtained by assembling the direct backlight shown in FIG.
The end is the lower surface of the upper frame FLM-U, the right mold M
It has a size such that it overlaps the upper surfaces of the LD-R and the left mold MLD-L, respectively.

On the other hand, the upper frame FLM-U, the right mold MLD-R and the left mold MLD-L
Since the optical sheets are combined by LT, a concave HOL is formed at each end of these optical sheets to avoid these screws. By providing the recessed HOL not at the corner of each optical sheet but at a distance from the corner, the laminate of optical sheets is gripped by the upper frame FLM-U, the right mold MLD-R and the left mold MLD-L, and mechanically. Difficult to shift due to severe vibration. In addition, by gripping the end of the optical sheet, problems such as scattering of transmitted light around the optical sheet are solved.

The direct type backlight shown in FIG. 15 has an upper mold MLD-U and a lower mold MLD-D. The upper surface of each of the upper mold MLD-U and the lower mold MLD-D extends in the direction intersecting the extending direction of the right mold MLD-R and the left mold MLD-L on the lower surface of the diffusion plate SCT, and the peripheral edges ( 22 (the upper side and the lower side in FIG. 22). Therefore, the upper mold MLD-U and the lower mold M
Each of the LD-Ds is spaced apart from each other in a region between the right mold MLD-R and the left mold MLD-L on the lower surface of the diffusion plate SCT.

While both the right mold MLD-R and the left mold MLD-L have shapes facing the lower surface and side surfaces of the periphery of the optical sheet, the upper mold MLD-U and the lower mold MLD-D It faces only the lower surface of the peripheral edge of the optical sheet. In other words, the upper mold MLD-U and the lower mold MLD-D can reduce the area in the main surface of the liquid crystal panel because there is no portion facing the side surface of the optical sheet. It is suitable for a so-called narrow frame of the device.

Further, since the lower portion (lower surface) of each of the upper mold MLD-U and the lower mold MLD-D is supported by the upper surface of the lower frame FLM-D, the stability of the entire direct-type backlight increases. . Thus, the direct-type backlight structure shown in FIG. 22 is suitable for reducing the thickness of the liquid crystal display device.

As the diffusion plate SCT in the direct type backlight described above, the diffusion plate SCT conventionally used in FIGS. 25 and 26 can be used, but the diffusion plate of the embodiment described below is used. Thereby, the light utilization rate is further improved, and the screen luminance of the liquid crystal panel can be made uniform and high.

FIG. 16 shows a sixth embodiment of the liquid crystal display device according to the present invention.
FIG. 3 is a schematic cross-sectional view of a diffusion plate for explaining an example. The diffusion plate SCT of the present embodiment is one surface of a transparent plate preferably made of an acrylic resin plate, that is, a light emitting surface (surface opposite to the linear light source) S
An unevenness DB is formed only on F-E, and the light incident surface SF-I facing the linear light source CFL is a flat surface.

With this configuration, part of the incident light L becomes reflected light L _R and is directed toward the reflector. FIG.
For 5 to scattered light L _S at the light incident surface SF-I as shown hardly occurs, it is possible to direct the reflected light L _R reflector or controlled to again diffuser direction by the reflection sheet.

FIG. 17 shows a lower frame FL having a reflection function.
FIG. 17 is a schematic explanatory view of a light utilization mode when a direct-type backlight having a mountain-shaped reflecting plate REF in the MD is combined with a diffusion plate having projections and depressions only on an emission surface shown in FIG. 16.

A large part of the light L incident on the entrance surface SF-1 from the linear light source is transmitted to the exit surface SF-E and becomes illumination light for the liquid crystal panel. Reflected light L _R reflected by the incident surface SF-1 of the diffusion plate SCT is recycled is reflected back diffusion plate SCT direction by the reflection plate REF Yamagata as illumination light of a liquid crystal panel. It is needless to say that in the case where the lower frame FLM-D has a reflecting function or is provided with a reflecting sheet, these reflected lights are also reused.

The amount of the reflected light L _R becomes larger than that of the conventional diffuser, and the brightness distribution on the screen of the liquid crystal panel can be made uniform by adjusting the curved shape, height, position, etc. of the mountain-shaped reflector REF. Control. Diffuser SC
The reflected light that has been reflected again by the incident surface SF-I of T is also reused again.

Therefore, it is easy to control the luminance distribution of the illumination light with the reflector to obtain the luminance uniformity on the screen of the liquid crystal panel.

By using the diffuser plate SCT of the present embodiment as the diffuser plate shown in FIGS. 11 to 15 described above, it is possible to obtain an effect in addition to the effects of the structures of the first to fifth embodiments of the present invention. And a high quality liquid crystal display device having the same.

FIG. 18 is an external view showing an example of a display monitor on which the liquid crystal display device according to the present invention is mounted.
The backlight constituting the liquid crystal display device mounted on the screen of the monitor, that is, the display section has the configuration of the embodiment of the present invention described above.

The liquid crystal display device according to the present invention is not limited to the display monitor as described above, but can be used for a monitor of a desktop personal computer, a notebook personal computer, a television receiver, and a display device of other devices.

FIG. 19 is an explanatory diagram of a configuration of a general active matrix type liquid crystal display device to which the present invention is applied and a drive system. This type of liquid crystal display device includes a liquid crystal panel PNL and a data line (also referred to as a drain signal line or a drain line) driving circuit (I) around the liquid crystal panel PNL.
C chip), that is, a drain driver DDR, a scanning line (also referred to as a gate signal line or a gate line) driving circuit (I
C chip), that is, a display control device CRL which is a display control means having a gate driver GDR and supplying display data, a clock signal, a gray scale voltage and the like for image display to the drain driver DDR and the gate driver GDR.
The power supply circuit PWU is provided.

Display data from an external signal source such as a computer, a personal computer, and a television receiver circuit and a control signal clock, a display timing signal, and a synchronization signal are transmitted to the display control device C.
Input to RL. The display control device CRL includes a gradation reference voltage generator, a timing controller TCON, and the like, and converts display data from the outside into data in a format suitable for display on the liquid crystal panel PNL.

Display data and a clock signal for the gate driver GDR and the drain driver DDR are supplied as shown. The carry output of the previous stage of the drain driver DDR is directly supplied to the carry input of the next stage drain driver.

FIG. 20 is a block diagram showing a schematic configuration of each driver of the liquid crystal panel and a signal flow. The drain driver DDR includes a data latch unit for display data such as a video (image) signal and an output voltage generation circuit. Also,
The gradation reference voltage generation unit HTV, multiplexer MPX, common voltage generation unit CVD, common driver CDD, level shift circuit LST, gate-on voltage generation unit GOV, gate-off voltage generation unit GFD, and DC-DC converter D / D are shown in FIG. The power supply circuit PWU is provided.

FIG. 21 is a timing chart showing display data input from the signal source (main unit) to the display control device and signals output from the display control device to the drain driver and the gate driver. The display control device CRL receives a control signal (clock signal, display timing signal, synchronization signal) from a signal source, and transmits a clock D1 (CL1), a shift clock D2 (CL2), and display data as control signals to the drain driver DDR. At the same time, a frame start instruction signal FLM, a clock G (CL3) and display data are generated as control signals to the gate driver GDR.

In the system using the low voltage differential signal (LVDS signal) for transmitting the display data from the signal source,
An LVDS signal from the signal source is mounted on a board (interface board) on which the display control device is mounted.
The signal is converted into an original signal by a VDS receiving circuit and then supplied to the gate driver GDR and the drain driver DDR.

As is apparent from FIG. 21, the shift clock signal D2 (CL2) of the drain driver is the same as the frequency of the clock signal (DCLK) and display data input from the main body computer or the like. High frequency of 40 MHz (megahertz). The liquid crystal display device having such a configuration has features such as thinness and low power consumption, and tends to be widely used as a display device in various fields in the future.

According to the embodiments of the present invention described above,
In addition to preventing a decrease in the luminous efficiency of the linear light source to prevent the display quality from deteriorating, it also eliminates the lack of brightness around the liquid crystal panel in a direct-type backlight in which a plurality of the linear light sources are arranged, and Liquid crystal that enables high-brightness and high-quality image display by controlling the light from the linear light source and the light reflected from the diffuser by the reflector and the diffuser plate to improve the light utilization rate and uniformity of the luminance distribution of the linear light source A display device can be obtained.

[0096]

As described above, according to the present invention,
In order to increase the brightness of the screen of the liquid crystal panel, it is possible to suppress a decrease in luminous efficiency due to an increase in the amount of applied current of the linear light source constituting the backlight and an increase in the amount of heat generated in the electrode portion due to an increase in the number of the light sources. Deterioration of the display quality of the liquid crystal panel can be avoided.

Further, it is possible to provide a liquid crystal display device in which a backlight in which a plurality of linear light sources are arrayed eliminates a lack of luminance around the liquid crystal panel to obtain a high luminance and high quality image display.

Further, it is possible to obtain a liquid crystal display device capable of displaying a high-luminance and high-quality image with improved light utilization and uniformity of the luminance distribution.

[Brief description of the drawings]

FIG. 1 is a main part side view showing a holding structure of a linear light source constituting a backlight for explaining a first embodiment of a liquid crystal display device according to the present invention.

FIG. 2 is a main part top view of FIG. 1 as viewed in the direction of arrow A.

FIG. 3 is a front view of FIG. 2 as viewed from the direction of arrow B.

FIG. 4 is a main part side view showing a holding structure of a linear light source constituting a backlight for explaining a second embodiment of the liquid crystal display device according to the present invention.

5 is a main part top view of FIG. 4 as viewed from the direction of arrow A. FIG.

FIG. 6 is a front view of FIG. 5 as viewed from the direction of arrow B.

FIG. 7 is a side view of a main part showing a holding structure of a linear light source constituting a backlight for explaining a third embodiment of the liquid crystal display device according to the present invention.

8 is a main part top view of FIG. 7 as viewed from the direction of arrow A. FIG.

FIG. 9 is a front view of FIG. 8 as viewed from the direction of arrow B.

FIG. 10 is a side view of an essential part showing a holding structure of a linear light source constituting a backlight for explaining a fourth embodiment of the liquid crystal display device according to the present invention.

FIG. 11 is an exploded perspective view illustrating the overall configuration of a backlight for explaining a fifth embodiment of the liquid crystal display device according to the present invention.

FIG. 12 is a schematic cross-sectional view similar to FIG. 23, illustrating an example of arrangement of linear light sources in a direct-type backlight using a plurality of linear light sources.

13 is a cross-sectional view of a principal part along line DD of FIG. 11, illustrating an example of a specific structure of a backlight of the liquid crystal display device according to the present invention.

14 is a cross-sectional view of a principal part along line EE of FIG. 11 for explaining an example of a specific structure of a backlight of the liquid crystal display device according to the present invention.

FIG. 15 is a developed perspective view showing a more specific configuration example of a direct-type backlight according to the present invention.

FIG. 16 is a schematic sectional view of a diffusion plate for explaining a sixth embodiment of the liquid crystal display device according to the present invention.

FIG. 17 shows a direct-type backlight having a chevron-shaped reflector REF on a lower frame FLM-D having a reflection function;
FIG. 7 is a schematic explanatory view of a light utilization mode when a diffusion plate having irregularities formed only on the exit surface shown in FIG.

FIG. 18 is an external view showing an example of a display monitor on which the liquid crystal display device according to the present invention is mounted.

FIG. 19 is a diagram illustrating a configuration of a general active matrix type liquid crystal display device to which the present invention is applied and a driving system.

FIG. 20 is a block diagram showing a schematic configuration of each driver of the liquid crystal panel and a signal flow.

FIG. 21 is a timing chart showing display data input from a signal source (main body) to a display control device and signals output from the display control device to a drain driver and a gate driver.

FIG. 22 is a developed perspective view illustrating an example of a conventional direct-type backlight.

FIG. 23 is a schematic cross-sectional view illustrating an example of arrangement of linear light sources in a direct-type backlight using a plurality of linear light sources.

FIG. 24 is a schematic diagram of a principal part showing an example of a CFL support structure of the backlight shown in FIG. 22;

FIG. 25 is a schematic cross-sectional view of a diffusion plate used in a conventional direct-type backlight.

FIG. 26 shows a direct type backlight having a chevron-shaped reflector REF on a lower frame FLM-D having a reflection function;
FIG. 4 is a schematic explanatory view of a light utilization mode when the diffusion plate having unevenness on both sides shown in FIG.

[Explanation of symbols]

 FLM-U Upper frame FLM-D Lower frame MLD-L Left mold MLD-R Right mold SCT Diffusion plate SF-I Light entrance surface SF-E Exit surface DB Unevenness SCTS Diffusion sheet PRS Prism sheet CFL Linear light source (cold cathode fluorescent light Light) CFL-E Linear light source at the end ELD electrode part ESP power supply line GB Insulation cushion material (rubber cushion) MP Heat dissipation plate.

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Takeshi Ken Saito 3350 Hayano, Mobara-shi, Chiba Prefecture Within Hitachi Electronics Devices Co., Ltd. (72) Inventor Kazuyoshi Tanaka 3350 Hayano, Mobara-shi, Chiba Hitachi Electro-tronic Devices Inside Shizu Corporation (72) Inventor Shigeo Shimano 3350 Hayano, Mobara City, Chiba Prefecture Inside Hitachi Electronics Devices Co., Ltd. (72) Inventor Takanori Yamazaki 3350 Hayano, Mobara City, Chiba Prefecture Inside Hitachi Electronic Devices Corporation (72) Inventor Takaaki Kitada 3300 Hayano, Mobara-shi, Chiba Prefecture Within Hitachi, Ltd. Display Group (72) Inventor Kazunari Ueda 3300, Hayano, Mobara-shi, Chiba Prefecture F-term in Display Group, Hitachi, Ltd. 2H089 HA40 JA10 JA11 QA06 RA05 TA14 TA 17 TA18 2H091 FA11Z FA14Z FA31Z FA42Z HA07 LA04 LA17 LA18 5G435 AA03 AA12 BB12 BB15 EE26 FF03 FF06 GG24

Claims (8)

[Claims] 1. A liquid crystal display device comprising: a plurality of linear light sources each having an electrode portion at an end portion; and a backlight provided on a rear surface of a liquid crystal panel via an optical compensation sheet. It has a lower frame formed of a metal plate, and has a heat radiating member thermally coupled to the lower frame made of a metal material surrounding the electrode portion of the linear light source with an insulating cushion material interposed therebetween. Liquid crystal display. 2. The liquid crystal display device according to claim 1, wherein said heat radiation member is formed by cutting and raising a part of said lower frame. 3. A liquid crystal display device comprising a plurality of linear light sources each having an electrode portion at an end portion, and a backlight provided on the rear surface of a liquid crystal panel via an optical compensation sheet. The plurality of linear light sources to be configured are arranged in parallel in the longitudinal direction with respect to the back surface of the liquid crystal panel, and the linear light sources located at both ends of the plurality of linear light sources are arranged close to the liquid crystal panel side. Characteristic liquid crystal display device. 4. The backlight comprises: a lower frame made of a metal material; a plurality of linear light sources arranged in parallel with the lower frame; an upper frame for holding the plurality of linear light sources together with the lower frame; The liquid crystal display device according to claim 3, further comprising an optical compensation sheet laminated on the frame. 5. An electrode part of the linear light source includes a heat radiating member thermally coupled to the lower frame made of a metal material surrounded by an insulating cushion material. 5. The liquid crystal display device according to 4. 6. The liquid crystal display device according to claim 5, wherein said heat radiating member is formed by cutting and raising a part of said lower frame. 7. The optical compensatory sheet includes a diffusion plate located immediately above the plurality of linear light sources, and has diffusion unevenness on a back surface of the diffusion plate with respect to the plurality of linear light sources and the plurality of linear light sources. 7. The liquid crystal display device according to claim 4, wherein the surface facing the light source is a flat surface. 8. A plurality of linear light sources having a peak on a side opposite to the diffuser plate between the linear light sources, and the line is gradually increased as the distance from the peaks to the diffuser plate increases. 8. The liquid crystal display device according to claim 7, further comprising a chevron-shaped reflector having a curved surface approaching the light source.