JP3091725B2 - Liquid crystal display - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an LCD (liquid crystal display), and more particularly to a combination arrangement of an LCD cell and a circuit board.

[0002]

2. Description of the Related Art CRTs have been used as broadcast televisions, computers or various monitor outputs. In recent years, various flat displays have been used for these displays, contributing to miniaturization and thinning of devices. doing.
In particular, such a flat display is indispensable for making a computer portable and compact, and various types of liquid crystal displays, plasma displays, fluorescent display panels, and the like have been proposed. However, in general, a liquid crystal display, that is, a liquid crystal display device which has a small power consumption and obtains a stable display operation is widely used. Good computer is obtained.

FIG. 6 shows a conventional general liquid crystal display device, in which a well-known LCD cell 10 is connected to a display circuit board 1.
2 and fixed.

The LCD cell 10 itself has a structure in which a liquid crystal is sealed between two glass plates forming a common electrode and a segment electrode, and a polarizing plate is usually provided on the outer surfaces of both glass plates.

A predetermined display circuit element is mounted on the back side of the circuit board 12 so as to supply a predetermined drive voltage to the common electrode and the segment electrode of the LCD cell 10. A desired driving voltage is supplied to the LCD cell by connecting the pins with a pin or by using a conductive rubber or the like, and an arbitrary display operation is achieved.

Conventionally, an I cell is directly connected to an LCD cell.
It has been proposed to reduce the size of the device by mounting a C circuit. For example, an IC is directly mounted on a glass surface of an LCD cell as a COG (chip-on-glass) method to reduce the size and thickness.

Another conventional method is TAB.
It has been proposed to integrate an LCD cell and an IC circuit mounted on an FPC by a method.

[0008]

However, in such a conventional liquid crystal display device, as is apparent from FIG. 6, the LCD cell 10 and the display circuit board 12 are superimposed as a whole, so that the size and thickness of the liquid crystal display device are reduced. However, there is still a problem that the thickness of a portable computer which is strictly required is large.

[0009] Therefore, it has been the actual situation that the thickness of the display has not yet been reduced to a satisfactory level as a display incorporated in the lid of the above-mentioned computer which is carried in an attache case or the like.

[0010] In the conventional COG method described above, I
In order to reduce the input resistance of C, a metal film is required not only for the ITO of the LCD cell but also for the input pattern to the IC, and as a result, there is a problem that the cost of the LCD cell increases. In addition, in this COG method, if even a part of the IC mounted on the LCD cell becomes defective, the LCD cell itself must be discarded, and a defect is found after mounting the IC including such a defective part. in case of,
There is a problem that the production yield is remarkably reduced, and further, such an integrated cell requires a substrate for input.

Also, in the conventional TAB system which is another conventional system, it is necessary to form bumps for connecting the LCD cells, which increases the FPC cost and requires an input substrate. .

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above-described problems, and an object of the present invention is to provide an improved liquid crystal display device which does not deteriorate its functional characteristics while further reducing the thickness of the liquid crystal display device. .

[0013]

SUMMARY OF THE INVENTION The present invention has been made to achieve the above object and has the following features .

First, the present invention relates to an LCD cell having a liquid crystal sealed between a cell substrate having an electrode terminal formed on a peripheral portion of the surface and another cell substrate forming a pair with the cell substrate. A circuit board, on which a display circuit element is mounted and connected to an electrode terminal on the cell substrate,
The circuit board and the corresponding electrode terminal on the cell board are connected by a flat cable bent so as to be folded back into a U-shape or an S-shape . Furthermore, the above U character
Connection to the corresponding cell board by flat cable
The corresponding circuit board is located at the side edge of the LCD cell.
And a flat cable connection surface of the circuit board and a flat cable connection surface of the circuit board face each other.

The circuit board connected to the corresponding cell board by the flat cable bent so as to be folded in the S-shape has a corresponding cell at the lateral end of the LCD cell.
Le substrate and at least partially overlaps, and is characterized in that the flat cable connecting surface of the cell substrate, and a flat cable connecting surface of the circuit board are arranged together so as to face the same direction.

The flat cable is bent in a U-shape, in other words, bent once, or bent in an S-shape, that is, bent twice, so that the circuit board and the glass board are connected. A liquid crystal display device can be configured by efficiently arranging the corresponding cell substrates in a space-saving manner with good workability. For example, it is easy to arrange a circuit board and a corresponding cell board so as to overlap each other at least partially so that the circuit board can be accommodated within the same thickness as the LCD cell, and the overall thickness can be reduced. This makes it possible to obtain a thin liquid crystal display device suitable for a portable computer.

Still another feature of the present invention is that, in the above liquid crystal display device, the display circuit element mounted on the circuit board is mounted on the back side of the liquid crystal display device of the circuit board. Further, the circuit board is divided into a first circuit board for driving a first electrode and a second circuit board for driving a second electrode, and the one or the other cell corresponding to the one of the flat cables is provided. It is characterized by being connected to an electrode terminal of a substrate. Further, the first circuit board is bent in a U-shape.
Connected to the cell substrate by a flat cable
The first circuit board and the cell board at least partially overlap each other.
Overlapping and flat cable connection surface of the cell board
And the flat cable connection surface of the first circuit board is oriented
They are arranged to meet each other. The second circuit board is S-shaped
The other cell substrate is bent by a flat cable
And the second circuit board and the other cell board are connected to each other.
At least partially overlap and the cell substrate
And the flat cable of the circuit board
Are arranged so that both connection surfaces face the same direction.
And features.

With such an arrangement, the first circuit board
Connect the flat cable connection surfaces of the board and the second circuit board together
Can be on the back side of the liquid crystal display device, improving the reliability of the device
You can aim up. In addition, the flash of these circuit boards
Display circuit elements are mounted on the same back side as the
The protection of this display circuit element and the display of the element
It is also possible to prevent electromagnetic noise from leaking outside the
It will be easier.

In each of the above liquid crystal display devices,
Flat connecting the circuit board and the corresponding cell board
Set cables longer than the minimum required connection path distance.
Flat cable is strongly bent locally
Is prevented, and the workability of assembling the device is dramatically improved.
To improve.

Another feature of the present invention is that
A cell substrate on which electrode terminals are formed; and a pair with the cell substrate.
LC with liquid crystal sealed between other cell substrates
A D cell and a power supply on the cell substrate on which the display circuit element is mounted.
And a circuit board connected to the pole terminals.
The circuit board and the corresponding electrode terminals on the board
Is bent so that it folds at least once.
And at least part of the return path
The cable facing distance is between the circuit board and the electrode on the board.
The cable facing distance of the cable facing the terminal
Connected by a flat cable
It is to be continued. Flat cable in such a relationship
Position the LCD cell and circuit board so that the
Can be locally bent to a flat cable
Assemble the device efficiently and without space
It becomes possible.

In the embodiments described below, the pair of “cell substrates” is specifically “common glass or segment glass”, and the “first electrodes” formed on the cell substrates, respectively. The “second electrode” is a “common electrode (or segment electrode)” and a “segment electrode (or common electrode)”. In addition, the first electrode and the second electrode
The "first circuit board" and the "second circuit board" connected to the electrodes, respectively.
The “circuit board” corresponds to a “common circuit board (or a segment circuit board)” and a “segment circuit board (or a common circuit board)”.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a plan view showing an exploded state of a part of the liquid crystal display device according to the embodiment of the present invention.

The liquid crystal display device according to the present embodiment comprises a display device with a backlight. An EL (electroluminescence) light emitting plate 22 and an LCD cell 24 for forming a backlight are stacked on a holder case 20 to form a cell holder and a common circuit board. A screw fixing arrangement 30 is provided.

The LCD cell 24 has a laminated arrangement of a common glass 26 and a segment glass 28 in which liquid crystal is sealed in the same manner as in the prior art.

As is well known, a common electrode is disposed on the surface of the common glass 26, and the common electrode terminal extends to the periphery of the common glass 26, that is, to the right end 26a in FIG. Similarly, a well-known segment electrode is also arranged on the surface of the segment glass 28, and the terminal of the segment electrode extends to the periphery indicated by reference numeral 28a.

In the present embodiment, the display circuit board is divided into a common circuit board 30 and a segment circuit board 32, and these two boards 30, 32 are respectively connected to the electrode terminals 26 of the common glass 26 and the segment glass 28 described above.
a, 28a.

Therefore, in the embodiment, the length of the segment circuit board 32 is set substantially equal to the width of the terminal 28a of the segment glass 28, while the length of the common circuit board 30 is set to the length of the common glass 26. Terminal 26
The width is set substantially equal to the sum of the width of a and the width of the segment circuit board 32. As a result, when the liquid crystal display device is assembled, the overall size is set to be a rectangle having the minimum area.

The common circuit board 30 and the segment circuit board 32 are made of a heat-resistant resin board on which both sides are copper-coated, and the lower surface is mounted with an LCD driver IC. These driver ICs are mounted on a substrate with bare chips, wire-bonded, and then resin-sealed. As a result, the plane space of each substrate is reduced. Wirings for input signals and power are mounted on the upper surface pattern of each board, and electrical connection is made to each driver IC through through holes, thereby forming each of the circuit boards 30 and 32 with a minimum width. are doing.

The common electrode terminal 26a and the common circuit board 30 are electrically connected by a flat cable 34. Similarly, the segment electrode terminal 28a and the segment circuit board 32 are electrically connected by a flat cable 36. Have been.

As is well known, the flat cable 36
Is also known as a heat seal connector, in which silver and graphite printed wiring are provided on a flexible thin polyester film substrate of 25 to 50 μm, and further, electrode terminals 26 are provided.
a, 28a and a hot-melt type adhesive are printed on the electrical connection portions with the circuit boards 30 and 32, and the cable itself can be freely bent by such a heat seal connector, so that a simple operation can be performed. A low-cost connector that is easily bonded and has high connection reliability can be formed.

FIG. 2 is a sectional view showing a connection state between the common electrode terminal 26a of the common glass 26 and the common circuit board 30.

In the figure, the common glass 2 of the LCD cell 24 is attached to the holder case 20 via a cushion rubber 38.
6 is fixedly held. As is apparent from the figure, LC4 is provided between the common glass 26 and the segment glass 28.
0 is enclosed and held, and polarizing plates 42 and 44 are laminated on the surfaces of both glasses 26 and 28, respectively. In the gap between the holder case 20 and the LCD cell 24 formed by the cushion rubber 38, the above-described EL light emitting plate 22 for backlight is detachably inserted.

Normally, the life of the EL is several thousand hours, and it is indispensable to replace the EL in practical use. However, according to the structure shown in the embodiment, the EL inserted into the gap is, for example, the left side of the holder It can be easily replaced without removing screws or the like from the opening.

On the other hand, the end of the holder case 20 further extends leftward in the figure, and the common circuit board 30 is fixed and held by set screws 46 as shown in the figure.
In this embodiment, a display circuit element 48 such as a common-side drive IC is mounted on the common circuit board 30 toward the back surface side of the liquid crystal display device, and even in an assembled state as shown in FIG. The thickness of the liquid crystal display 30 does not exceed the thickness of the LCD cell 24, and in the present invention, the liquid crystal display device can be significantly thinned.

In the embodiment, a circuit element such as a relatively large capacitor such as 50 is mounted on the common circuit board 30 in some cases. However, as shown in FIG. EL for backlight
When the light-emitting plates 22 and the like are stacked, the arrangement of the present invention makes it possible to incorporate a circuit element having a large thickness such as the element 50 into the display without sufficiently increasing the thickness of the liquid crystal display device. Become.

As described above, the electrode terminals 26a of the common glass 26 and the common circuit board 30 are electrically connected by the flat cable 34. As shown in FIG. 3, the flat cable 34 is bent once. One end is connected to the common circuit terminal 26a, and the other end is connected to a terminal provided at an end of the common circuit board 30.

After the connection is completed in this manner, in the present invention, the end 30a of the common circuit board 30 is connected to the end of the common glass 26, in the embodiment, the above-mentioned common electrode terminal 26a. They are arranged one on top of the other so that their cable connection surfaces face each other. In this state, the common circuit board 30 and the shield plate 45 are firmly fixed to the holder case 20 by set screws 46,
At the same time, the LCD cell 24 is also firmly held by the holder case 20.

One end of the shield plate 45 is connected to the ground end of the common circuit board 30. The shield plate 45 and the holder case 20 are electrically connected to each other via screws, thereby connecting the common circuit board 30 to the common circuit board 30. The shield plate 45 covers to prevent leakage of electromagnetic noise to the outside.

In the present embodiment, in such a state, the flat cable 34 is folded back, that is, bent in a U-shape to connect the common circuit board 30 and the electrode terminals 26 a of the common glass 26. Become. Therefore, as is apparent from FIG. 2, the LCD cell 24 and the common circuit board 3
0 can be provided in such a way that it is partially overlapped at its ends and the plane space can also be significantly reduced. Further, as is apparent from FIG. 2, the flat cable 34 bent in a U-shape is sufficiently longer than the minimum required to connect the common glass 26 and the common circuit board 30. By increasing the length of the flat cable 34 in this manner, workability in assembling is achieved. Further, the connected flat cable is reliably prevented from being peeled off due to a slight displacement between the circuit board and the glass substrate.

FIG. 4 shows the connection between the electrode terminals 28a of the segment glass 28 and the segment circuit board 32. The segment circuit board 32 is firmly held by the set screw 52 with respect to the holder case 20. An upper support plate 54 is disposed on the segment circuit board 32, and the upper support plate 54 is integrally fixed to the segment circuit board 32 and the holder case 20 with a set screw 52, thereby obtaining a firmly connected and fixed structure. ing. That is, the upper receiving plate 5
4 has one end 54a extending to the end of the segment glass 28 of the LCD cell 24, and firmly holds the LCD cell 24 in the holder case 20. The upper receiving plate 54 and the holder case 20 are electrically connected via screws, and can effectively shield the segment circuit board 32 that generates electromagnetic noise.

A display circuit element 56 such as a segment drive IC is also arranged on the segment circuit board 32 toward the back side of the LCD cell 24. The thickness of the upper receiving plate 54 is substantially the same as the thickness of the upper polarizing plate 44, and can accommodate the circuit board and the mounted display circuit elements without increasing the thickness of the liquid crystal display device.

FIG. 5 shows a state in which the segment glass 28 and the segment circuit board 32 are simply electrically connected by the flat cable 36 as shown in FIG. 1. As is apparent from FIG. The ICs mounted on each of the common circuit boards 30 are the LCD cells 24.
And the connector electrodes of these boards are provided on the side where the IC is arranged. The electrode terminal 28a of the segment glass 28 faces the lower side of the figure, and the connector electrode 32a of the segment circuit board 32 also faces the lower side. Therefore, as shown in FIG. 4, the flat cable 36 is double-folded, that is, S-shaped by laying it over the segment glass 28 at the connector end 32a of the segment circuit board 32 as shown in FIG. So that they are electrically and mechanically connected in a stable state. In addition, the flat cable 36
As is clear from FIG. 4, the length is set longer than the minimum necessary for connecting the segment glass 28 and the segment circuit board 32, similarly to the flat cable 34 in FIG. Improvements have been made and the reliability of the device after connection has been improved.

The LCD cell 24 is fixed to the metallic holder case 20 together with the circuit boards 30 and 32, and is further fixed to the computer housing by a mounting tab or the like (not shown). As a result, an external force applied to the computer housing is received by the metallic holder case 20, and a structure can be provided in which the LCD cell 24 and the circuit boards 30, 32 are not affected by the external force.

As described above, each of the circuit boards 30, 32
Are arranged substantially on the same plane as the liquid crystal cell 24 with the circuit element mounted thereon, and a part thereof is placed on top of the glass constituting the liquid crystal cell. Thus, a thin liquid crystal display device can be obtained.

In the above-described embodiment, the LCD cell is a double-sided polarizing plate type cell with a backlight, but the cell itself can be of any type.

[0047]

As described above, according to the present invention,
By connecting a circuit board and a corresponding cell board with a flat cable bent so as to be folded in a U-shape or an S-shape, the circuit board and the cell board are efficiently arranged in a space-saving manner. And a liquid crystal display device in which the thickness and the planar dimension are extremely thin and small can be realized. Therefore, a display device particularly suitable for a portable computer or the like can be provided at a low price.

[Brief description of the drawings]

FIG. 1 is a plan view of a preferred embodiment in which a part of a liquid crystal display device according to the present invention is disassembled.

FIG. 2 is a cross-sectional view of a main part showing a connection state between a common-side electrode terminal and a circuit board in FIG. 1;

FIG. 3 is an explanatory view showing a folded state of the flat cable in FIG. 2;

4 is a cross-sectional view of a main part showing a connection state between a segment-side electrode terminal and a circuit board in FIG. 1;

FIG. 5 is an explanatory view showing a folded state of the flat cable in FIG. 4;

FIG. 6 is a plan view showing a schematic configuration of a conventional liquid crystal display device.

[Explanation of symbols]

20 holder case, 24 LCD cell, 26 common glass, 26a common electrode terminal, 28 segment glass, 28a segment electrode terminal, 30 common circuit board, 32 segment circuit board, 34, 36 flat cable.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-61-185782 (JP, A) JP-A-60-78075 (JP, U) JP-A-60-154921 (JP, U) JP-A-60-60 165985 (JP, U) Japanese Utility Model Showa 61-167690 (JP, U) Japanese Utility Model 1-140519 (JP, U) Japanese Utility Model Utility Model 62-67676 (JP, U) Japanese Utility Model Utility Model 1-1120188 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) G02F 1/1333 G02F 1/1345 G09F 9/00 348

Claims (7)

(57) [Claims] 1. An LCD cell comprising liquid crystal sealed between a cell substrate having an electrode terminal formed on a peripheral portion of a front surface thereof and another cell substrate forming a pair with the cell substrate, and a display circuit element. And a circuit board connected to an electrode terminal on the cell substrate, wherein the circuit board and the corresponding electrode terminal on the substrate are:
The circuit board is connected by a flat cable bent so as to be folded in a U-shape, and the circuit board is provided at a lateral end of the LCD cell at a front end.
At least partially overlap with the corresponding cell substrate, and
Connect the flat cable connection surface of the corresponding cell
Routed so that the flat cable connection surface of the circuit board faces
A liquid crystal display device characterized by being placed . 2. An LCD cell comprising liquid crystal sealed between a cell substrate having an electrode terminal formed on a peripheral portion of a front surface thereof and another cell substrate forming a pair with the cell substrate, and a display circuit element. And a circuit board mounted with the electrode terminals on the cell substrate, wherein the circuit board and the corresponding electrode terminals on the cell substrate are folded in an S-shape. Connected by a bent flat cable, the circuit board is located at the side edge of the LCD cell,
At least partially overlap with the corresponding cell substrate, and
Connect the flat cable connection surface of the corresponding cell
The same direction as the flat cable connection surface of the circuit board
A liquid crystal display device characterized by being arranged to face . 3. The liquid crystal display device according to claim 1 , wherein the display circuit element is mounted on a back surface side of the liquid crystal display device of the circuit board. apparatus. 4. A liquid crystal display device according to any one of claims 1-3, wherein the circuit board includes a first circuit board for driving the first electrode, the second circuit board for driving the second electrode And the liquid crystal display device is connected to a corresponding one of the electrode terminals of the one or other cell substrate by the flat cable. 5. The liquid crystal display device according to claim 4 , wherein the first circuit board is connected to the cell board by a U-shaped flat cable, and the first circuit board and the cell board are connected to each other. Are arranged so that at least a part thereof overlaps each other, and the flat cable connection surface of the cell board and the flat cable connection face of the first circuit board face each other. The second circuit board is bent in an S shape. The second circuit board and the other cell board are at least partially overlapped with each other by a flat cable, and the flat cable connection surface of the cell board and the flat board of the circuit board are connected to each other. A liquid crystal display device, wherein both the cable connection surfaces are arranged in the same direction. 6. A liquid crystal display device according to any one of claims 1 to 5, a flat cable that connects the cell substrate corresponding to the circuit board is sufficiently longer than the minimum required connection path distance A liquid crystal display device characterized by the above-mentioned. 7. An LCD cell in which liquid crystal is sealed between a cell substrate having electrode terminals formed on a peripheral portion of the surface, and another cell substrate forming a pair with the cell substrate, and a display circuit element. And a circuit board connected to an electrode terminal on the cell substrate, wherein the circuit board and the corresponding electrode terminal on the substrate are:
In bent flat cables to wrap one or more times
And the cable in at least a part of the return path
Distance between the circuit board and the connection terminal on the board.
Wider than the cable facing distance of the cable facing between
A liquid crystal display device, wherein the liquid crystal display device is connected by a flat cable arranged so as to extend .