JP2002333606A - Liquid crystal display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display to which a flexible board can be easily fixed in a detachable manner, and in which sufficient measures are taken against EMI(Electromagnetic Interference). SOLUTION: The liquid crystal display in which a liquid crystal panel 1 is held between a front cover 2 and a back case 4 and integrated together, is provided with a 1st control circuit board 8 which is mounted on the liquid crystal panel 1, and is connected with a signal line, a 2nd control circuit board 14 arranged in the rear surface of the back surface case 4, and a flexible board 16 which is connected with both of the circuits 8 and 14, and equipped with a metallic film 18 for the measures against EMI. The liquid crystal display has a holding part 19 which is formed by cutting out a part of the back case 4, and a fixing means consisting of a protection plate 20 made of a resin supported by the holding part 19 in a detachable manner. When the protection plate 20 is attached to the holding part 19, the flexible board 16 is held in the state it is pressed against the back case 4 by the protection plate 20. Then, the metallic film 18 is grounded through the back surface case 4.

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 using a direct-type backlight in which a plurality of linear lamps such as fluorescent lamps are disposed immediately below the back of a liquid crystal panel.

[0002]

2. Description of the Related Art Up to now, CRTs have been mainly used for color televisions, but recently, liquid crystal televisions have been put to practical use by making use of the advantages of a thin liquid crystal display device and low power consumption. In a liquid crystal display device for a television or a large monitor, a TFT type LCD using a TFT as a switching element for driving each pixel is mainly used. In the case of this TFT type, TF is placed on one of the glass substrates constituting the liquid crystal panel.
Form scanning lines and signal lines connected to T in a matrix,
Input terminals for the scanning lines and the signal lines are arranged on the periphery of the glass substrate. In general, the number of signal lines is larger than the number of scanning lines, so the input terminals of the signal lines are arranged at the long side of the glass substrate, and the input terminals of the scanning lines are arranged at the short side of the glass substrate. . The input terminal of the signal line is connected to the source drive circuit board via TAB, and the input terminal of the scan line is connected to TA.
Gate drive circuit boards are connected via B, and signals are supplied from the drive circuit boards to the respective lines. A control circuit board is provided separately from the source drive circuit board and the gate drive circuit board, and the control circuit board and each drive circuit board are electrically connected by a flexible board.

[0003] There are two types of backlights disposed on the back side of the liquid crystal panel: a side edge type in which a linear lamp is disposed on the side surface of the light guide plate, and a direct type in which a light source is disposed immediately below the rear side of the liquid crystal panel. The liquid crystal display devices of notebook PCs and small portable terminals are particularly required to be thinner, so side-edge type backlights are mainly used, but the liquid crystal display devices of liquid crystal televisions and large monitors require particularly high brightness. Mainly a direct backlight is adopted. In the case of the direct type, a plurality of light sources such as fluorescent lamps are arranged on the back side of the liquid crystal panel so as to face the liquid crystal panel, and a diffusion plate, a dimming plate and the like are arranged between the light source and the liquid crystal panel. The fluorescent lamp is, for example, Al
In the case of the direct type, the fluorescent lamp and the liquid crystal panel are used in order to supply light of uniform intensity to the entire display area of the liquid crystal panel and prevent uneven brightness. It is necessary to adjust the interval, and as the number of fluorescent lamps decreases, the interval between the LCD panel and the LCD panel increases accordingly.Thus, the backlight unit becomes thicker than the side edge type, and the rear case is the rear side of the LCD panel. The shape becomes overhanging. The light of the fluorescent lamp is efficiently supplied to the liquid crystal panel by using the inner surface of the rear case as a reflector, or disposing a reflector between the rear case and the fluorescent lamp.

FIG. 7 shows a rear perspective view of the liquid crystal display device. Reference numeral 50 denotes a frame for housing and supporting the liquid crystal panel, 51 denotes a metal rear case, and 52 denotes a front cover having an open display portion. The frame 50 accommodating the liquid crystal panel is sandwiched between the rear case 51 and the front cover 52, and the fixed portion 53 around the front cover 52 is bent toward the rear case 51 to be integrated. A control circuit board is attached to the rear surface of the rear case 51 and is covered with a protective case 54. 5
Reference numeral 5 denotes a flexible board for electrically connecting the source drive circuit board mounted on the liquid crystal panel to the control circuit board mounted on the rear case 51, and 56 electrically connects the gate drive circuit board and the control circuit board. It is a flexible board and supplies each signal from the control circuit board.

[0005]

Conventionally, the flexible substrates 55 and 56 have been left free without being fixed. However, in the case of a liquid crystal display device for a TV or a large monitor, the number of pixels increases due to the increase in size and definition, so that the number of signal lines also increases, and in particular, the flexible substrate 55 connected to the source drive circuit substrate increases. I will. Therefore, when handling the liquid crystal display device, the flexible substrate 55 is easily caught, and there is a problem that the connection failure or breakage of the flexible substrate 55 occurs.

There is also a method of fixing the back case of the flexible substrate with a double-sided tape or the like. However, in this case, it is necessary to remove or replace the double-sided tape every time maintenance of the liquid crystal display device is performed. There were drawbacks.

Further, in the case of a conventional flexible substrate, measures against EMI (Electromagnetic Interference) have not been sufficient. Since liquid crystal display devices for TVs are required to be large and have high image quality, EMI countermeasures for the flexible substrate 55, which has become larger with an increase in the number of pixels, have become more important than ever, and such measures have been required.

Accordingly, an object of the present invention is to propose a liquid crystal display device in which a flexible substrate can be easily and detachably fixed, and in which sufficient EMI measures are taken.

[0009]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a liquid crystal panel in which liquid crystal is sealed between a pair of substrates and scanning lines and signal lines are arranged in a matrix on one of the substrates. A liquid crystal comprising: a plurality of light sources disposed directly below the panel; a rear case that houses the light sources and covers the back side of the liquid crystal panel; and a front cover that is disposed on the front of the liquid crystal panel and fixed to the rear case. In a display device, a first control circuit board mounted on a liquid crystal panel and supplying an image signal to a signal line, a second control circuit board disposed on a back surface of a rear case, and a first control circuit board are provided. A flexible board for electrically connecting the second control circuit board and a fixing means for detachably fixing the flexible board to the rear case are provided.

Further, the fixing means of the present invention includes a holding portion formed on the rear case, and a protection plate detachably supported by the holding portion, and the protection plate is flexible by the protection plate when the protection plate is attached to the holding portion. It is characterized in that the substrate is held while being pressed against the rear case.

According to the above configuration, the flexible substrate can be easily attached to the rear case, the flexible substrate can be prevented from being damaged during the manufacture and maintenance of the liquid crystal display device, the assembling workability can be improved, and the storage space for the flexible substrate can be improved. Is reduced. In addition, the flexible substrate can be easily removed even during maintenance, and the maintainability is improved.

Further, the present invention is characterized in that the holding portion is formed by cutting and raising a part of the rear case, and the protection plate is made of resin and can be bent. With the above configuration, inexpensive fixing means can be realized.

According to the present invention, there is provided a rear case in which at least a portion to which a flexible substrate is pressed is made of metal;
A flexible substrate having a metal film for MI countermeasures, wherein the metal film of the flexible substrate is electrically connected to the metal part of the rear case when the flexible substrate is fixed to the rear case by the fixing means.

With the above configuration, the EM of the flexible substrate
The metal film for I measures is grounded via the rear case, and EMI measures for the flexible substrate are taken.

The present invention also relates to a flexible substrate EMI.
As a countermeasure metal film, a metal foil bonded over most of the flexible substrate is used.
With the above configuration, EMI countermeasures can be taken at low cost.

The present invention also relates to an EMI of a flexible substrate.
As a countermeasure metal film, a metal mesh that covers most of the flexible substrate is used.

The present invention also relates to an EMI of a flexible substrate.
As a countermeasure metal film, a multi-layered flexible substrate and a GND pattern formed over one layer are used.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a rear perspective view of a liquid crystal display device according to an embodiment of the present invention, FIG. 2 is a front view of the liquid crystal display device, FIG. 3 is a front view of the liquid crystal display device with a front cover removed, and FIG. FIG. 5 is a side view of the apparatus, and FIG.
FIG. 6 is an enlarged schematic view of a region B in FIG.

In the liquid crystal panel 1, a pair of glass substrates 5 and 6 are bonded in a hollow shape, and a liquid crystal is sealed between the glass substrates 5 and 6. On one glass substrate 5, a plurality of signal lines and a plurality of scanning lines are formed in a matrix, and a TFT is provided at an intersection of the signal line and the scanning line, and a pixel electrode is provided at a region surrounded by the signal line and the scanning line. Provide. The TFT connects a gate electrode to a scanning line, a source electrode to a signal line, and a drain electrode to a pixel electrode, controls ON / OFF of the TFT by a scanning signal supplied to the scanning line, and is supplied to the signal line. A voltage based on the image signal is supplied to the pixel electrode. On the other glass substrate 6, a light-shielding film is formed at a portion facing the scanning line and the signal line, and a color filter of a predetermined color is formed according to each pixel. Further, a common electrode is formed on the light-shielding film and the color filter so as to face the pixel electrode, and the arrangement state of the liquid crystal molecules is controlled by an electric field between the common electrode and the pixel electrode.

The glass substrate 5 on which the scanning lines and the signal lines are formed is slightly larger than the glass substrate 6 on which the color filters are formed, and when the glass substrates 5 are bonded together, The long side and the short side are exposed. The input terminal of the signal line is disposed on the exposed long side portion, and the input terminal of the scanning line is disposed on the exposed short side portion. The input terminal of the signal line is connected to a source drive circuit board (hereinafter, referred to as a source PWB) 8 as a first control circuit board via a TAB 7, and a source PW
An image signal is supplied from B8 to a signal line, an input terminal of the scanning line is connected to a gate drive circuit board (hereinafter, referred to as a gate PWB) 10 via a TAB 9, and a gate signal is supplied from the gate PWB10 to the scanning line. The source PWB 8 and the gate PWB 10 are both formed on a slender rectangular printed circuit board, and control circuits are arranged on the printed circuit board.

Reference numeral 3 denotes a frame made of resin, which has an opening at a central portion, and is provided with locking portions for abutting and positioning on a side portion of the glass substrate 5 at several places. When the liquid crystal panel 1 is placed on the frame 3, the glass substrate 5 comes into contact with the locking portion 11 so that the liquid crystal panel 1 can be held in the frame 3. A front cover 2 is provided on the front side of the liquid crystal panel 1 held by the frame 3.
The liquid crystal display device is configured by disposing a rear case 4 on the rear side and fixing the liquid crystal panel 1 and the frame body 3 with the front cover 2 and the rear case 4 sandwiched therebetween.

The front cover 2 is made of, for example, a metal such as Al, and has an opening at a portion corresponding to the display section of the liquid crystal panel 1. The peripheral portion of the front cover 2 is bent so as to cover the side surface of the frame 3, and a fixing portion 12 formed by cutting out a part of the peripheral portion is provided. This fixing part 1
The front cover 2 can be fixed to the rear case 4 by bending the front cover 2 toward the rear case 4.

In this embodiment, a direct-type backlight is used, and a plurality of light sources such as a plurality of fluorescent lamps are accommodated in the rear case 4. The fluorescent lamps are arranged along the longitudinal direction of the liquid crystal panel 1. Reference numeral 13 denotes a lead wire of a fluorescent lamp led out of the rear case 4. The rear case 4 is formed of a metal such as Al, and the inner surface of the rear case 4 efficiently reflects the light of the fluorescent lamp. The fluorescent lamp and the rear case 4
A reflection plate may be arranged between them. The shape of the rear case 4 protrudes greatly on the rear surface side so that a fluorescent lamp can be stored.

A control circuit board (hereinafter, referred to as control PWB) 14 as a second control circuit board is disposed on a part of the back surface of the back case 4.
The WB 14 is covered with a protective cover 15. The control PWB 14 includes a source PWB 8 and a gate PWB 10
A control circuit for supplying each signal is disposed. Reference numeral 16 denotes an FPC (flexible substrate) for connecting the source PWB 8 and the control PWB 14, and 17 denotes a gate PW.
FPC to connect B10 and control PWB14
(Flexible substrate). The FPC 17 is not shown in FIG. 1 because it is covered with the protective cover 15.

The FPC 16 is branched into two branches on the control PWB 14 side.
A wiring pattern for electrically connecting to the WB 14 is provided,
A metal foil 18 of Al or Cu, which is a metal film for EMI countermeasures insulated from the wiring pattern, is attached to the FPC 16. The hatched portion of the FPC 16 in FIG. The metal foil 18 is formed on most of the surface of the FPC 16 facing the rear case 4 and the surface not facing the rear case 4, and the metal foils 18 on both surfaces are electrically connected. The method of connecting the metal foils 18 on both sides includes a method of providing the metal foils 18 extending over both sides at the end of the FPC 16 and a method of forming a contact hole in an appropriate place of the FPC 16 and electrically connecting the metal foils 18 on both sides at the contact hole portion. May be performed. In this embodiment, the metal foil 18 is applied to the FPC 16.
Is applied, EMI countermeasures can be achieved with a simple configuration and at low cost.

Reference numeral 19 denotes a holding piece which is a holding portion formed on the rear case 4, and reference numeral 20 denotes a protection plate held by the holding piece 19. The holding piece 19 is formed by cutting and raising a part of the rear case 4, and is located between both sides in the width direction of the FPC 16 and the forked portion of the FPC 16. The protection plate 20 is formed in a horizontally long plate shape made of a resin such as plastic, and can be bent with respect to a force applied from its longitudinal direction, and has a restoring force that returns to an original shape when the applied force is removed. are doing. The protection plate 20 may be formed of metal. However, when a metal protection plate having a poor restoring force after being curved as compared with the resin protection plate 20 is used, the shape of the holding piece 19 and It is necessary to arrange the arrangement suitable for a metal protection plate. When attaching the protection plate 20 to the holding piece 19, one end of the protection plate 20 is hooked on one holding piece 19 located on the side of the FPC 16, and the FP is placed between the protection plate 20 and the rear case 4.
The protection plate 20 is bent with the C16 interposed, the other end of the protection plate 20 is inserted into the other holding piece 19 located on the side of the FPC 16, and the holding piece 19 is restored by the restoring force of the protection plate 20.
Fit into At this time, the protection plate 20 is supported and fixed by the holding piece 19, and the FPC 16 is attached to the rear case 4 while being pressed by the protection plate 20.

In this embodiment, the side surface portion (the portion where the FPC is located) of the rear case 4 that protrudes greatly toward the rear side is formed as an inclined surface, and the holding piece 19 is formed on the inclined surface to form the FP.
C16 is fixed. Therefore, when the FPC 16 is fixed to the rear case 4, the FPC 16 is not deformed into an unreasonable shape, and no extra load is applied to the protection plate 20 and the holding piece 19 pressing the FPC 16. In addition, by making the side surface portion of the rear case 4 to which the FPC 16 is fixed an inclined surface, a large space for forming the holding piece 19 and the like can be taken, so that the manufacturing of the holding piece 19 and the attaching / detaching work of the protection plate 20 are easy. Can be done.

When the FPC 16 is pressed against the rear case 4, the metal foil 18 of the FPC 16 is
, The metal foil 18 is grounded via the rear case 4, which is an EMI measure for the FPC 16. There are various methods of grounding the rear case 4, for example, a configuration in which the rear case 4 is connected to a ground line existing on each circuit board may be used. May be used.

In this embodiment, since the FPC 16 which has been free and is not fixed in the past is fixed to the rear case 4, it is possible to prevent the FPC 16 from being caught or damaged during assembly. Further, since the protection plate 20 is detachable from the holding piece 19, the FPC 16 can be easily removed at the time of maintenance, thereby improving the maintainability. Further, the storage space for the FPC 16 is reduced. In this embodiment, the rear case 4 is used as the fixing means.
Since the holding piece 19, which is partially cut and raised, and the protection plate 20 made of a resin such as plastic are used, it is possible to manufacture the protection plate 20 inexpensively and easily.

In this embodiment, the metal foil 18 is attached as a measure against the EMI of the FPC 16, but the present invention is not limited to this embodiment. For example, the entire FPC 16 may be covered with a metal mesh, and the metal mesh may be brought into contact with the metal back case 4. Also, FPC1
6, a GND (ground) pattern is formed on at least any one layer, for example, an outer layer over most of the FPC 16. Then, a configuration in which the GND pattern of the multilayer FPC and the rear case 4 are electrically connected to each other when the FPC 16 is held on the rear case 4 by the protective plate 20 is employed. Good.

It should be noted that embodiments other than the above-described embodiment are possible without departing from the gist of the present invention. For example, the protection plate may be screwed to the rear case, or a holding piece provided separately from the rear case may be fixed to the rear case. In this embodiment, a TFT is used as a switching element connected to a pixel electrode. However, the present invention is not particularly limited to a TFT, and an MIM or the like may be used as a switching element.

[0032]

According to the present invention, a flexible board for connecting a first control circuit board mounted on a liquid crystal panel to a second control circuit board disposed on the back surface of a rear case is provided.
It is to be detachably fixed to the rear case by fixing means, a holding portion formed on the rear case as this fixing means, a protective plate detachably supported by the holding portion,
When the protection plate is attached to the holding portion, the flexible substrate is held by being pressed against the rear case by the protection plate. Therefore, the flexible substrate can be easily detachably attached to the rear case, and the flexible substrate can be prevented from being damaged during manufacturing and maintenance of the liquid crystal display device, assembling workability is improved, and the storage space for the flexible substrate is reduced. . In addition, the flexible substrate can be easily removed even during maintenance, and the maintainability is improved.

Further, since the holding portion is formed by cutting and raising a part of the rear case, and the protection plate is formed of resin and can be bent, an inexpensive fixing means can be realized with a simple configuration. Work can be done easily.

When the flexible substrate is fixed to the rear case, the metal film of the flexible substrate is electrically connected to the metal part of the rear case, so that the metal film for EMI measures of the flexible substrate is grounded via the rear case. EMI measures can be taken for the flexible substrate. Also E
Since the metal foil bonded over most of the flexible substrate is used as the metal film for MI countermeasures, EMI countermeasures can be achieved with a simple configuration and at low cost.

[Brief description of the drawings]

FIG. 1 is a rear perspective view of a liquid crystal display device according to an embodiment of the present invention.

FIG. 2 is a front view of the liquid crystal display device with a front cover attached.

FIG. 3 is a front view of the liquid crystal display device with a front cover removed.

FIG. 4 is a side view of the liquid crystal display device.

FIG. 5 is an enlarged schematic view of a region A in FIG. 1;

FIG. 6 is an enlarged schematic diagram of a region B in FIG. 4;

FIG. 7 is a rear perspective view of a conventional liquid crystal display device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Liquid crystal panel 2 Front cover 3 Frame 4 Back case 8 Source PWB 14 Control PWB 16 FPC 19 Holding piece 20 Protection plate

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) H05K 9/00 H05K 9/00 R (72) Inventor Toshiya Nishio 3-201 Minamiyoshikata, Tottori-shi, Tottori Sanyo Electric Co., Ltd. In-house F-term (reference) 2H089 HA40 KA17 QA09 QA10 QA12 TA07 TA18 2H092 GA50 GA53 NA27 NA30 PA05 PA06 PA13 5E321 AA14 AA17 BB41 BB44 GG05 5E338 AA12 AA16 CC01 CC05 CC06 CD24 EE13 5G435 AA17 EE37 BB37

Claims (7)

[Claims] 1. A liquid crystal panel in which a liquid crystal is sealed between a pair of substrates and scanning lines and signal lines are arranged in a matrix on one substrate, a plurality of light sources disposed immediately below the liquid crystal panel, and the light source A liquid crystal display device, comprising: a rear case that accommodates the liquid crystal panel and covers a rear side of the liquid crystal panel; and a front cover that is disposed on the front of the liquid crystal panel and fixed to the rear case. A first control circuit board for supplying an image signal to the signal line and a second control circuit board disposed on the back surface of the back case.
Control circuit board, the first control circuit board, and the second
A liquid crystal display device, comprising: a flexible board for electrically connecting the control circuit board to the control circuit board; and fixing means for detachably fixing the flexible board to the rear case. 2. The fixing device according to claim 1, further comprising: a holding portion formed on the rear case; and a protection plate detachably supported by the holding portion, wherein the protection plate is attached to the holding portion. 2. The liquid crystal display device according to claim 1, wherein the flexible substrate is held by being pressed against the rear case by a protection plate. 3. The liquid crystal display device according to claim 2, wherein the holding portion is formed by cutting and raising a part of the rear case, and the protection plate is made of resin and is formed to be bendable. 4. The rear case, wherein at least a portion of the flexible substrate to be pressed is made of metal,
The flexible substrate having a metal film for countermeasures, wherein the metal film of the flexible substrate is electrically connected to the metal part of the rear case when the flexible substrate is fixed to the rear case by the fixing means. 4. The liquid crystal display device according to claim 1, wherein: 5. The liquid crystal display device according to claim 4, wherein the metal film for EMI measures of the flexible substrate is a metal foil bonded over most of the flexible substrate. 6. The liquid crystal display device according to claim 4, wherein the metal film for EMI measures on the flexible substrate is a metal mesh covering most of the flexible substrate. 7. The liquid crystal display device according to claim 4, wherein the metal film for EMI countermeasures of the flexible substrate is a GND pattern formed on the flexible substrate in a multilayer structure and over one layer. .