JP3003928B2 - 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 A CRT is used as a broadcast television, a computer, or various monitor outputs. In recent years, various flat panel displays have been used for these displays. Has contributed. In particular, such a flat panel display is indispensable for making the computer portable and compact, and various types of liquid crystal display, plasma display, fluorescent display panel and the like have been proposed. However, in general, a liquid crystal display, that is, a liquid crystal display device having a small power consumption and a stable display operation is widely used,
In a portable computer or the like, an extremely easy-to-use computer has been obtained by incorporating a liquid crystal display device into a lid.

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, in the present invention, a first glass substrate having an electrode terminal formed on a peripheral portion of a surface thereof;
An LCD cell configured by sandwiching liquid crystal between a glass substrate and a second glass substrate facing the same, and a display circuit element mounted thereon and connected to the corresponding electrode terminals on the first and second glass substrates, respectively. And a circuit board, wherein 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. Further, the circuit board is connected to corresponding electrode terminals of the first and second glass substrates by a flat cable, and the first circuit board is connected to the first glass substrate on a side of the second glass substrate. The second circuit board is superposed and arranged so that at least a part thereof faces the glass substrate, and the second circuit board is superposed on a side of the first glass substrate so that at least a part thereof faces the second glass substrate. Is done.

With such a configuration, the LCD cell and each circuit board are arranged on substantially the same plane. For this reason, it becomes easy to house and arrange each circuit board within a range similar to the thickness of the cell at the periphery of the LCD cell, so that the overall thickness is significantly reduced and a thin liquid crystal display device suitable for a portable computer or the like is provided. Can be obtained.

In another aspect of the present invention, the flat cable is arranged so that at least a part of the flat cable is bent in a space beside an LCD cell in which the glass substrate and the previous circuit board are overlapped and arranged. You. Thereby, LC
The flat cable is extremely efficiently accommodated in the space beside the LCD cell where the D cell and the circuit board are arranged to overlap each other, and a compact liquid crystal display device can be obtained.

Further, in addition to the above-mentioned contents of the present invention, each circuit board is arranged so as not to overlap with the opposing glass substrate of the glass substrate which is superimposed on the circuit board. With such an arrangement, the circuit board and the L are positioned so that each circuit board fits within the thickness of the LCD cell.
It can be placed around the CD cell.

In the embodiments described below, the above-mentioned "first glass substrate" and "second glass substrate" are specifically called "common glass (or segment glass)" and "segment glass (or common glass)". Glass) "
The “first” formed on the first and second glass substrates, respectively.
The “electrode” and “second electrode” are “common electrode (or segment electrode)” and “segment electrode (or common electrode)”. The “first circuit board” and the “second circuit board” connected to the first electrode and the second electrode, respectively,
It corresponds to a “common circuit board (or segment circuit board)” and a “segment circuit board (or common circuit board)”.

[0019]

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 enclosing liquid crystal and a segment glass 28 in the same manner as in the prior art, and a polarizing plate, which will be described later, is laminated on the surfaces of both glasses 26, 28.

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 this embodiment, the display circuit board is divided into a common circuit board 30 and a segment circuit board 32, and these two boards 30 and 32 are connected to the respective electrode terminals 26 of the common glass 26 and the segment glass 28, respectively.
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 formed of a heat-resistant resin board having both surfaces thereof affixed with copper, and an LCD driver IC is mounted on the lower surface. 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, 32, and the cable itself is 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 cross-sectional view showing the connection 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 in 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.

Further, 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, but 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 circuit terminals 26a of the common glass 26 and the common circuit board 30 are electrically connected by the flat cable 34, and as shown in FIG. The other end is connected to a terminal provided at an end of the common circuit board 30.

After the connection between the two is completed in this manner, in the present invention, the end 3 of the common circuit board 30 is
Reference numeral 0a denotes an end of the common glass 26, and in the embodiment, is overlapped with the common electrode terminal 26a. In this state, the common circuit board 30 and the shield plate 45
Is firmly fixed to the holder case 20 by a set screw 46, and at the same time, the LCD cell 24 is also
Firmly held.

One end of the shield plate 45 is connected to the ground end of the common circuit board 30, and 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 ground. The shield plate 45 covers to prevent leakage of electromagnetic noise to the outside.

In this embodiment, in such a state, the flat cable 34 connects the common circuit board 30 and the electrode terminal 26a of the common glass 26 by one turn. Therefore, as is apparent from FIG. 2, the LCD cell 24 and the common circuit board 30 are partially overlapped at their ends, and an arrangement can be provided in which the plane space can be significantly reduced.

Similarly, FIG. 4 shows the connection between the electrode terminal 28a of the segment glass 28 and the segment circuit board 32.
The upper receiving plate 54 is firmly held with respect to the segment circuit board 32 by a set screw 52, and the upper receiving plate 54 is arranged on the segment circuit board 32 by the set screw 52. A secure connection and fixing structure is obtained by fixing to the case 20. That is, the upper receiving plate 54 has one end 54a extending to the end of the segment glass 28 of the LCD cell 24, and
4 is firmly fixed to 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 equal to the thickness of the upper polarizing plate 44. The circuit board and each mounted display circuit element can be accommodated 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. 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, by arranging the segment glass 28 at the connector end 32a of the segment circuit board 32 so as to overlap with the segment glass 28, the flat cable 36 is folded twice as shown in FIG. Connected in a stable state mechanically and mechanically.

Therefore, the LCD cell 24 is connected to both circuit boards 3
0, 32 together with the metal holder case 20,
Furthermore, it is screwed and fixed to the housing of the computer by a mounting tab or the like (not shown). As a result, external force applied to the computer housing is received by the metallic holder case 20 and the
It is possible to provide the cell 24 and the circuit boards 30 and 32 with a structure in which external force does not reach.

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

[0044]

As described above, according to the present invention,
ADVANTAGE OF THE INVENTION According to the present invention, by arranging a circuit board on a corresponding glass substrate in the vicinity of an edge of an LCD cell, it is possible to realize a liquid crystal display device whose thickness and planar dimensions are extremely small and thin. It is possible to provide a low-cost display suitable for a portable computer or the like.

[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 bent state of the flat cable in FIG. 2;

FIG. 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 bent 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 front page (56) References JP-A-60-129729 (JP, A) JP-A-61-121078 (JP, A) JP-A-62-280889 (JP, A) JP-A-63-129 313187 (JP, A) Japanese Utility Model Showa 60-78075 (JP, U) Japanese Utility Model Showa 61-206929 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G02F 1/1345 G02F 1 / 1333 G09F 9/00 348

Claims (3)

(57) [Claims] 1. An LC having a liquid crystal sandwiched between a first glass substrate having electrode terminals formed on a peripheral portion of a front surface thereof and a second glass substrate facing the first glass substrate.
A liquid crystal display device comprising: a D cell; and a circuit board on which a display circuit element is mounted and connected to each of the electrode terminals on the corresponding first and second glass substrates. A first circuit board for driving a second electrode and a second circuit board for driving a second electrode, which are connected to corresponding electrode terminals of the first and second glass substrates by a flat cable, and The substrate is disposed on the side of the second glass substrate so as to be at least partially opposed to the first glass substrate, and the second circuit board is disposed on the side of the first glass substrate. A liquid crystal display device, wherein the liquid crystal display device is arranged so as to overlap at least a part of the second glass substrate. 2. The liquid crystal display device according to claim 1, wherein the flat cable is at least partially bent in a space beside an LCD cell in which the glass substrate and the previous recording substrate are arranged so as to overlap each other. A liquid crystal display device, wherein the liquid crystal display device is arranged so as to be arranged. 3. The liquid crystal display device according to claim 1, wherein the first circuit board is provided in parallel with the second glass substrate without overlapping with the second glass substrate, and The two-circuit board is provided with the first glass substrate without overlapping the first glass substrate.
A liquid crystal display device, which is provided side by side with a substrate.