JPH0521240U - Liquid crystal display - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a liquid crystal display device which can reduce the size of the structure, can eliminate display unevenness, improve display quality, and further improve reliability. is there. [Configuration] A glass substrate 22 in the liquid crystal display device 21,
A large number of drive circuit elements 36 are arranged on the wiring region 33 of 23. A pair of flexible wiring boards 41, 42 are arranged along the peripheral edge of the glass substrate 22, and the connection wiring 4 is provided for each drive circuit element 36 from the common signal line 45 that these have.
6 is drawn out, and the connection terminal at the tip thereof is connected to the signal line 37 on the glass substrate 22 via the anisotropic conductive resin 48 made of a thermosetting resin.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device having a configuration in which display data, display control signals, etc. are externally supplied via a flexible wiring board.

[0002]

[Prior Art]

 FIG. 13 is a plan view of a conventional COG (Chip On Glass) type liquid crystal display device 1. The liquid crystal display device 1 performs the display operation in the display area 4 with the liquid crystal interposed between the pair of glass substrates 2 and 3. This display operation is performed by a large number of drive circuit elements 6 arranged on the glass substrate 2 in the wiring region 5 which is not covered with the glass substrate 3. That is, the drive circuit element 6 is connected to the display electrode 7 extending in the display region 4. The display data and various control signals supplied to the drive circuit element 6 are supplied from the flexible wiring board 8, and the input to each drive circuit element 6 is formed on the glass substrate 2 by thin film technology. This is performed by a large number of signal lines 9, and each signal line 9 and a predetermined terminal of the drive circuit element 6 are connected by a connecting means such as a bonding wire.

The display electrode 7 and the signal line 9 are patterned by etching after forming ITO (indium oxide) by sputtering or the like, and further, a portion of the display electrode 7 outside the display region 4 and the signal line. In order to reduce the resistance, a laminated body of metal such as Cr + Al or Ni + Au having good conductivity is formed on the ITO layer 9 in order to reduce the resistance.

In the liquid crystal display device 1, transparent electrodes made of ITO (indium oxide) or the like are formed on the surfaces of the glass substrates 2 and 3 which face each other, and liquid crystal is filled between them to form a display area 4. Constitute. A peripheral portion of the display area 4 between the glass substrates 2 and 3 is sealed with a sealing material, and a deflection plate is attached to each outer surface.

The glass substrate 2 is formed to have a larger area than the glass substrate 3, includes the wiring region 5 protruding from the glass substrate 3, and forms a connection wiring 7 that is individually and integrally connected to the transparent electrode. To be done. The connection wirings 7 are connected to the drive circuit elements 6 arranged in a plurality in the wiring area 5 in a predetermined number, and the signal for inputting a control signal from the outside to the drive circuit elements 6 is provided. Lines 9 are formed on the glass substrate 2 by thin film technology.

In this conventional example, since the signal line 9 is fine and a long distance is routed over the entire wiring region 5, it is possible to reduce the resistance of the metal layer laminated on the ITO layer. It cannot be formed with a sufficient film thickness, and the signal line 9 has a wiring resistance of several .OMEGA. Further, when the signal line 9 is widened to reduce the resistance, the wiring region 5 increases, and the area of the liquid crystal display device 1 other than the display region 4 increases, which causes an inconvenience that the liquid crystal display device 1 increases in size. .. Furthermore, the delay in the signal caused by the wiring resistance and the stray capacitance associated with the wiring cannot be ignored, and there is a drawback that crosstalk occurs during the display operation.

FIG. 14 is an enlarged plan view of the signal line 9 on the glass substrate 2 and the conductor 10 of the flexible wiring substrate 8. The connection terminal 9a near the outer end of the signal line 9 and the connection terminal 10a near the outer terminal of the conductor 10 of the flexible wiring board 8 both have the same strip-like shape, and therefore they are connected by soldering or the like. Even in such a case, the adhesive strength is relatively low, and the connection terminals 9a and 10a are peeled off from each other due to use, and there are problems such as frequent lighting defects in the liquid crystal display device 1.

[0008]

[Problems to be solved by the device]

 In such a conventional example, although the resistance is reduced by the metal laminated body, the signal line 9 is extremely fine, and when the liquid crystal display device 1 is highly densified and highly refined, The signal line 9 becomes finer. As a result, a sufficiently low resistance has not been realized even if the above-mentioned laminated structure is used, and a signal voltage drop due to wiring resistance occurs in the display area 4 in a portion close to the flexible wiring substrate 8 and a portion distant from the flexible wiring substrate 8. It can no longer be ignored, and the display is uneven. This problem is particularly noticeable in a simple matrix type liquid crystal display device which is intended to realize high duty, high definition and high density.

As another conventional example for solving such inconvenience, there is JP-A-64-37355. In this conventional example, the same thing as the signal line 9 of FIG. 13 is formed on the flexible wiring board, and such a flexible wiring board is connected to the glass substrate along the arrangement direction of the drive circuit elements 6, The signal line of the flexible wiring board and the drive circuit element are connected. However, this conventional example has a problem that the reliability of connection between the flexible wiring board and the drive circuit element is low.

The object of the present invention is to solve the above-mentioned technical problems and to reduce the size of the structure, and to eliminate the display unevenness to improve the display quality. An object of the present invention is to provide a liquid crystal display device that improves the property.

[0011]

[Means for Solving the Problems]

 According to the present invention, liquid crystal is filled between a pair of glass substrates having different sizes to provide a display area, and one end of the glass substrate is not covered by the other glass substrate, and one end thereof faces the display area. A flexible wiring board having a plurality of strip-shaped conductors is arranged along the wiring area, and a wiring area is formed in which a plurality of conductors are arrayed so that the end faces the end of the glass substrate. A liquid crystal display device is formed by connecting a conductor end portion in a partial region and a strip conductor of a flexible wiring board via an anisotropic conductive resin.

The present invention is also a liquid crystal display device, wherein the anisotropic conductive resin is a thermosetting resin.

[0013]

In the liquid crystal display device according to the present invention, a plurality of conductors are arranged in a blank area of one glass substrate which is not covered by the other glass substrate. One end of this conductor faces the display area and the other end extends toward the end of the glass substrate, and a display signal is sent. On the other hand, the flexible wiring board has a plurality of strip-shaped conductors arranged along the glass substrate, and the conductors extending along the inner and outer directions on the glass substrate are flexible wiring boards. The strip-shaped conductors are opposed to each other, and they are fixed with an anisotropic conductive resin.

Therefore, it is possible to eliminate the necessity of arranging the printed wiring on the glass substrate along the wiring region, reduce the area of the wiring region, and reduce the size of the liquid crystal display device. Further, since fine routing printed wiring on the glass substrate is eliminated, wiring resistance due to such routing printed wiring can be significantly reduced, and display quality can be improved. Moreover, the reliability of the liquid crystal display device is significantly improved.

[0015]

【Example】

 1 is a plan view of a liquid crystal display device 21 according to an embodiment of the present invention, FIG. 2 is an enlarged plan view of the vicinity of an end portion of the liquid crystal display device 21, and FIG. 3 is a section line X3-X3 of FIG. It is the sectional view seen from above. In the liquid crystal display device 21, transparent electrodes 26 and 27 made of ITO (indium tin oxide) or the like are formed on opposite surfaces of the glass substrates 22 and 23, respectively, and a liquid crystal 28 is filled between them to form a display area 29. To do. The peripheral edge of the display area 29 between the glass substrates 22 and 23 is sealed with a sealant 30, and the deflection plates 31 and 32 are attached to the outer surfaces of the display regions 29.

The glass substrate 22 is formed to have a larger area than the glass substrate 23, has a wiring region 33 protruding from the glass substrate 223, and is connected to the transparent electrodes 26 and 27 individually and integrally with a connection wiring 35. Is formed. The connection wirings 35 are connected in a predetermined number to the drive circuit elements 36 arranged in the wiring area 33, and a signal line 37 for inputting a control signal from the outside to the drive circuit elements 36 is provided. It is formed on the glass substrate 22 by thin film technology.

In the present embodiment, when forming various circuit wirings on the glass substrates 22 and 23, ITO is first patterned into the shapes of the transparent electrodes 26 and 27, the connection wirings 35 and the signal lines 37, and then an example is formed thereon. As a metal layer made of Cr + Al or Ni + Au, the resistance of these circuit wirings is reduced. Further, the metal layer in a range corresponding to the inside of the display region 29 is removed by etching or the like to leave only the transparent electrodes 26 and 27.

A pair of flexible wiring boards 41, 42 is arranged along the pair of long sides of the rectangular plate-shaped glass substrate 22 at the peripheral edge of the glass substrate 22, and extends over the length of each of the long sides. Placed. The flexible wiring board 41 includes a connecting portion 43, which is longer than the long side of the glass substrate 22, and a driving circuit element 36 arranged on the glass substrate 22 from the connecting portion 43. A plurality of connecting portions 44 projecting toward one side are formed. In the connection part 43, a plurality of common signal lines 45 having a relatively wide width are formed over substantially the entire length of the connection part 43. From each common signal line 45, as many connection wirings 46 as the number of common signal lines 45 are formed on the connection portion 44. In each of the connection wirings 46, a portion that becomes a multiple wiring with any one of the common signal lines 45 is insulated from each other as described later.

The flexible wiring board 42 also has the same structure as the flexible wiring board 41, and when referring to the respective constituent parts, the reference numerals 43 to 46 are indicated by adding a subscript a.

FIG. 4 is an enlarged plan view of the vicinity of one drive circuit element 36 of the liquid crystal display device 21. The signal line 37 connected to the drive circuit element 36 extends from the drive circuit element 36 toward the drive circuit element 36 of the glass substrate 22 toward the most recent peripheral edge portion, and the portion near the end portion is the flexible wiring. A connection terminal 47 used for connection with the substrates 41 and 42 is configured. The signal line 37 is configured as a laminated structure of ITO and a metal layer as described above, and the connection terminal 47 uses the metal layer as it is as a connection terminal, or the same kind or various kinds of metal on the metal layer. The layers may be further laminated.

FIG. 5 is a sectional view taken along section line X5-X5 in FIG. In the liquid crystal display device 21 of the present embodiment, as described above, the pair of glass substrates 22 and 23 are assembled facing each other, and a large number of drive circuit elements 36 are arranged on the wiring region 33 of the glass substrate 22. The connection between the signal line 37 connected to the drive circuit element 36 on the glass substrate 22 and the flexible wiring board 41, that is, the connection between the signal line 37 and the connection wiring 46 of the flexible wiring board 41 is as follows. For example, it is fixed by an anisotropic conductive resin 48 having a thermosetting synthetic resin material such as AC-7052-27 (manufactured by Hitachi Chemical Co., Ltd.) as a base material, and electrical connection is achieved. In order to improve the mechanical strength of the connection between the glass substrate 22 and the flexible wiring substrate 41, the flexible wiring substrate 41 from the end of the glass substrate 22 on the side opposite to the glass substrate 23 on the flexible wiring substrate 41 side. A reinforcing resin layer 49 made of, for example, an ultraviolet curable resin or the like is formed in the range extending over the area and the area on the opposite side of the flexible wiring board 41. Further, the protective resin layer 49 on the glass substrate 23 side of the glass substrate 22, the drive circuit element 36, and the range including the end surface of the glass substrate 23 are covered, and a protective layer made of a non-water-permeable material such as silicon resin. 50 is formed.

FIG. 6 is a sectional view taken along the section line X6-X6 in FIG. In the example of FIG. 6, three common signal lines 45 are formed by a thick film technique such as screen printing of copper paste. Such a resin film 39 is covered with an insulating layer 51, a through hole 52 is formed on a common signal line 45 corresponding to the type of the connection wiring 46 formed on the resin film 39, and the common signal line 45 is connected to each common signal line 45. It is possible to obtain a plurality of connection wirings 46 insulated from the other common signal lines 45. The remaining portion of the connection wiring 46 excluding the connection terminal 53, which is the tip portion, is covered with an insulating film 54.

FIG. 7 is an enlarged plan view in the vicinity of the connection terminal 47 of the connection wiring 46 on the flexible wiring board 41. In the present embodiment, the connection terminal 47, which is the tip of the connection wiring 46 of the flexible wiring board 41, gradually expands in the width direction near the end of the connection wiring 46, as shown in FIG. It is divided into a plurality of connecting fingers 55. On the other hand, the tip end of the signal line 37 of the glass substrate 22 is formed in a strip shape similar to the conventional one. In this embodiment, since the connection terminal 47 of the connection wiring 46 is composed of the plurality of connection fingers 55 in this way, the mechanical connection to the signal line 37 by the anisotropic conductive resin 48 becomes extremely good.

FIGS. 8 and 9 show an anisotropic method in which the flexible wiring board 8 in the liquid crystal display device 1 of the conventional example and the configuration of the present embodiment as shown in FIG. 7 are used, and moreover, a thermosetting resin is used as an adhesive. 6 is a graph showing a tensile strength quantity distribution when a conductive resin 48 is used. That is, the line 56 of FIG. 8 shows the case of the conventional product, and the line 57 of FIG. 9 shows the case of this embodiment. In line 56, the center value of horizontal tensile strength is about 24 kgf, whereas in line 57 of FIG. 9 showing the characteristics of this embodiment, the horizontal tensile strength giving the peak value of the upward convex curve is 30 Kgf or more. Thus, the value is much higher than the value shown in FIG.

FIG. 10 is a graph showing the change over time in the connection resistance between the flexible wiring board 41 and the glass substrate 22 provided with the anisotropic conductive resin containing the thermosetting resin described above. 11 is a graph when the same characteristics are measured in a high temperature and high humidity atmosphere. Line 58 is the case where a thermoplastic resin (AC-5052, manufactured by Hitachi Chemical Co., Ltd.) is used as the anisotropic conductive resin, and line 59 is the case where the above-mentioned thermosetting resin is used. .. In the heat shock, heat was applied by sequentially repeating bidirectionally 40 ° C. for 30 minutes, room temperature for 5 minutes, and 100 ° C. for 30 minutes. It was confirmed that when the thermoplastic resin was used in this state, the connection resistance increased with the passage of time, whereas the thermosetting resin hardly changed the connection resistance.

FIG. 11 shows a case where the thermoplastic resin described in FIG. 10 is used and a case where a thermosetting resin is used. The heat environment is maintained at a high temperature of 85 ° C. and 85% RH and a high humidity environment. Then, the connection resistance was measured. The line 60 is a case where a thermoplastic resin is used, and the line 61 is a case where a thermosetting resin is used. Even in this case, it was confirmed that the connection resistance increases with the passage of time when the thermoplastic resin is used, whereas the connection resistance hardly changes when the thermosetting resin is used.

From the above points, the thermosetting resin as described above is used as the base material of the anisotropic conductive resin used for connecting the glass substrate 22 and the flexible wiring substrates 41 and 42 of this embodiment. It turned out to be suitable. Further, in this embodiment, the shape of the connection terminal 47 in the connection wiring 46 on the side of the flexible wiring boards 41 and 42 is comb-shaped as described with reference to FIG. The reliability of electrical and electrical connections has been dramatically improved.

As described above, in the present embodiment, the wiring region 33 on the glass substrate 22 can be made smaller in area than the conventional example, and the liquid crystal display device 21 can be downsized as a whole. Further, in contrast to the conventional example in which the circuit wiring necessary for inputting a display signal or data to the drive circuit element 30 is laid out on the glass substrate 22, in the present embodiment, the flexible wiring boards 41 and 42 are arranged as described above. It realizes easy wiring. Therefore, the common signal line 45 and the connection wiring 46 described above can be selected relatively wide and large in thickness, and the occurrence of display unevenness or crosstalk due to the increase in wiring resistance as described in the conventional example can be prevented. It can be prevented, and the display quality can be remarkably improved. Further, by forming the connecting terminals 47 of the flexible wiring boards 41 and 42 into a comb-tooth shape, the adhesion and the distribution of the anisotropic conductive resin 48 can be made uniform, and the reliability of the liquid crystal display device can be improved. Can be improved.

As shown in FIG. 12A, the connection method of the drive circuit element 36 on the glass substrate 22 includes a connection wiring 35 formed by laminating an ITO layer 54 and a metal layer 55 on the glass substrate 22 and a signal. The line 37 may be connected by a face-down bonding method using bumps 51 such as solder, or the drive circuit element 36 may be placed on the glass substrate 22 as shown in FIG. The connection wiring 35 and the signal line 37 having the above structure may be connected to each other by using the bonding wire 56.

[0030]

As described above, according to the present invention, among a pair of glass substrates in a liquid crystal display device, a plurality of conductors are arranged in a blank area of one glass substrate which is not covered by the other glass substrate. .. One end of this conductor extends toward the display area and the other end extends toward the end of the glass substrate, and a display signal is passed. On the other hand, the flexible wiring board has a plurality of strip-shaped conductors arranged so as to follow the glass substrate, and the conductors extending along the inner and outer directions on the glass substrate are flexible wiring boards. The strip-shaped conductors are opposed to each other, and they are fixed with an anisotropic conductive resin.

Therefore, it is possible to eliminate the need for arranging the printed wiring on the glass substrate along the wiring area, reduce the area of the wiring area, and reduce the size of the liquid crystal display device. Further, since fine routing printed wiring on the glass substrate is eliminated, wiring resistance due to such routing printed wiring can be significantly reduced, and display quality can be improved. Moreover, the reliability of the liquid crystal display device is significantly improved.

[Brief description of drawings]

FIG. 1 is a plan view of a liquid crystal display device 21 according to an embodiment of the present invention.

FIG. 2 is an enlarged plan view of a flexible wiring board 41 and its vicinity.

3 is a cross-sectional view taken along the section line X3-X3 in FIG.

FIG. 4 is an enlarged plan view in the vicinity of a drive circuit element 36.

5 is a cross-sectional view taken along the section line X5-X5 in FIG.

6 is a cross-sectional view taken along the section line X6-X6 in FIG.

7 is an enlarged plan view of a flexible wiring board 41 and its vicinity showing connection terminals 47. FIG.

FIG. 8 is a graph illustrating the operation of this embodiment.

FIG. 9 is a graph illustrating the operation of this embodiment.

FIG. 10 is a graph illustrating the operation of this embodiment.

FIG. 11 is a graph illustrating the operation of this embodiment.

FIG. 12 is a cross-sectional view showing another configuration example of the present invention.

FIG. 13 is an enlarged plan view of a conventional liquid crystal display device 1.

FIG. 14 is an enlarged plan view in the vicinity of a connection terminal 9a of a signal line 9 of a conventional example.

[Explanation of symbols]

 21 liquid crystal display device 22, 23 glass substrate 33 wiring region 35 connection wiring 36 drive circuit element 37 signal line 42 common signal line 44 connection conductor

Claims (2)

[Scope of utility model registration request] 1. A display area is provided by filling liquid crystal between a pair of glass substrates having different sizes, and a blank area of one glass substrate is not covered with the other glass substrate.
A flexible wiring board having a plurality of strip-shaped conductors is formed along a wiring area in which a plurality of conductors are arranged, one end of which faces the display area and the other end of which faces the end of the glass substrate. And a strip-shaped conductor of the flexible wiring substrate and a conductor end portion in the end portion region of the glass substrate are connected via an anisotropic conductive resin. 2. The liquid crystal display device according to claim 1, wherein the anisotropic conductive resin is a thermosetting resin.