JP2009116064A - Liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-reliability liquid crystal display device which is free of peeling of a sheet material. <P>SOLUTION: Disclosed is the liquid crystal display device constituted by bonding an array substrate 1 and a counter substrate 2 together with a seal material 5 applied over the array substrate 1 and closing liquid crystal between the array substrate 1 and counter substrate 2. At the position where the seal material 5 is contact with a transfer electrode 7 provided in a peripheral region of the array substrate 1, a coating film (a protective film 6 or a gate insulating film 13 and interlayer dielectrics 16 and 17) formed covering a display region of the array substrate 1 is expanded to come into contact with the seal material 5. For example, the expanded portion 6a of the protective film 6 comes into contact with the seal material 5 to increase the bonding area of the seal material 5. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a liquid crystal display device in which an array substrate and a counter substrate are bonded together with a sealing material, and a liquid crystal is sealed between the substrates, and in particular for preventing peeling of the sealing material at a transfer electrode forming portion. Related to technology.

  In a liquid crystal display device, a liquid crystal cell is formed by adhering an array substrate and a counter substrate with a sealing material, and a liquid crystal material is sealed therein and formed on the display area of the array substrate corresponding to each pixel. An image display is performed by providing a switching element (a thin film transistor for driving a pixel) and driving the switching element by a driving circuit. In this case, one thin film transistor is required to drive the liquid crystal of each color element. Therefore, in the display area where image display is performed, wiring lines such as signal lines and scanning lines are formed vertically and horizontally on the array substrate. The pixel driving thin film transistors are arranged in a matrix at positions where they intersect.

  In the liquid crystal display device having the above-described configuration, a transfer electrode for connecting the counter electrode formed on the counter substrate and the circuit on the array substrate side is necessary, and a plurality of transfer electrodes are installed outside the display area of the array substrate. Has been. In this case, for the purpose of reducing the area of the outer region (so-called frame region) of the sealing material and narrowing the frame region, the transfer electrode is arranged close to the sealing material.

For example, Patent Document 1 discloses a liquid crystal display device having the following configuration. That is, in the liquid crystal display device described in Patent Document 1, a notch is formed at the end of the alignment film of the TFT substrate on the transfer electrode side, and the notch is positioned on the transfer electrode. Then, a sealing member made of a resin containing conductive particles is formed on the peripheral edge of the alignment film. At this time, the transfer electrode is covered with the seal member. Then, the TFT substrate and the counter substrate are bonded together by the seal member, and the transfer electrode of the TFT substrate and the counter electrode of the counter substrate are connected to each other. Thereafter, a liquid crystal layer is sealed between the TFT substrate and the counter substrate to obtain a liquid crystal display device.
JP 2006-301115 A

  By the way, in the liquid crystal display device having the above-described configuration, the counter substrate is bonded by the sealing material applied on the array substrate. However, the problem of peeling due to a decrease in the adhesive strength is a major issue. In particular, the peeling at the position where the transfer electrode formed on the array substrate and the seal material contact each other is remarkable.

  The transfer electrode is made of metal, and when a sealing material is formed on the transfer electrode, the adhesive force is significantly reduced. That is, the contact area of the sealing material with respect to the array substrate is substantially reduced as compared with other portions, and it is difficult to ensure a sufficient adhesive force. As a result, the sealing material is peeled off, which causes peeling of the array substrate and the counter substrate. The peeling significantly reduces the quality of the liquid crystal display device.

  The present invention has been proposed in view of the conventional situation as described above, and an object thereof is to provide a highly reliable liquid crystal display device in which a sealing material is not peeled off.

  In order to achieve the above-described object, the liquid crystal display device of the present invention has an array substrate and a counter substrate bonded together by a sealing material applied on the array substrate, and the liquid crystal is sealed between the array substrate and the counter substrate. The coating film formed so as to cover the display region of the array substrate is in contact with the sealing material at a position where the sealing material is in contact with the transfer electrode provided in the peripheral region of the array substrate. It is characterized by being extended.

  For example, a coating film formed of a transparent resin is superior in the adhesiveness of a sealing material compared to a metal. Therefore, if the coating film formed in the display area is expanded so as to be in contact with the sealing material, the substantial bonding area of the sealing material is expanded, and sufficient adhesive force is provided even at the position where the sealing material is in contact with the transfer electrode. Is secured.

  According to the present invention, it is possible to sufficiently secure the adhesive strength between the array substrate and the counter substrate, prevent the array substrate and the counter substrate from being peeled off, and provide a highly reliable liquid crystal display device.

  Hereinafter, embodiments of a liquid crystal display device to which the present invention is applied will be described in detail with reference to the drawings.

  The liquid crystal display device includes a liquid crystal display panel and a backlight unit that is disposed on the back side of the liquid crystal display panel and that irradiates the liquid crystal display panel with backlight. Here, the structure of the liquid crystal display panel will be described. The liquid crystal display panel includes, for example, an array substrate 1 and a counter substrate 2 as shown in FIG. 1, and the liquid crystal between the array substrate 1 and the counter substrate 2. An image is displayed by driving thin film transistors (pixel transistors) whose layers are formed in a matrix on the array substrate 1 as switching elements.

  In the display area H of the array substrate 1, pixel electrodes are formed in a matrix corresponding to each pixel, scanning lines are formed along the row direction of the pixel electrodes, and signal lines are formed along the column direction. Has been. Further, pixel transistors are formed at the intersections between the scanning lines and the signal lines. On the other hand, on the counter substrate 2, a counter electrode is formed of a transparent conductive material so as to face the pixel electrode, and a color filter is formed corresponding to each pixel.

  Further, in the peripheral region of the array substrate 1 (the frame region of the liquid crystal display panel), there are a signal line drive circuit that supplies a drive signal to signal lines arranged and formed on the array substrate 1 and a gate drive circuit that drives the gate lines. The driving IC 3 and the like constituting these driving circuits are mounted. Furthermore, a transfer electrode for connecting the counter electrode formed on the counter substrate 2 and the circuit on the array substrate 1 side is provided. For example, conductive particles are distributed on the transfer electrode or a conductive paste. For example, an electrical connection between the counter electrode and the transfer electrode is achieved. Furthermore, a flexible wiring board 4 for connection to an external circuit is connected to the array substrate 1, and signal transmission / reception between the signal line driving circuit, the gate driving circuit, etc. and the external circuit is performed by the flexible wiring. This is done via the substrate 4.

  The array substrate 1 and the counter substrate 2 described above are bonded to each other by a sealing material applied onto the array substrate 1, and a liquid crystal material is injected into a space (gap) sealed by this. Hereinafter, a seal structure in which the array substrate 1 and the counter substrate 2 are bonded with a sealant will be described in detail.

  FIG. 2 shows an example of a seal pattern arrangement formed on the array substrate 1. A sealing material 5 is applied on the array substrate 1 at a position slightly inside the outer peripheral edge, and the counter substrate 2 is stacked on the seal substrate 5 so that the array substrate 1 and the counter substrate 2 are bonded to each other.

  The sealing material 5 is applied and formed over the entire periphery of the array substrate 1 so as to surround the display area H, in a shape generally along the outer periphery, and after the liquid crystal is injected, The entrance (not shown) is also closed, and the injected liquid crystal material is sealed in the gap between the array substrate 1 and the counter substrate 2. The pattern of the sealing material 5 can be freely changed according to the shape and size of the display area H. For example, the sealing material 5 can be installed anywhere except in the display area H. is there.

  In the display region H surrounded by the sealing material 5 described above, pixel transistors, signal lines, gate lines, and the like are formed. In this example, a transparent resin film covering these is formed as the protective film 6. Yes. The shape of the protective film 6 is rectangular according to the shape of the display area H.

  Further, as described above, a signal line driving circuit, a gate line driving circuit, and the like are formed in an area outside the sealing material 5 (so-called frame area), and further, the circuit on the array substrate 1 side and the counter substrate 2. A transfer electrode 7 is formed for electrical connection with the counter electrode formed on the substrate. The transfer electrode 7 has a larger area than other electrodes and wirings in order to make the electric resistance as small as possible. In this example, the transfer electrodes 7 are formed at two locations on the short side of the array substrate 1, for a total of four locations. However, the number of transfer electrodes 7 and their positions can be arbitrarily set.

  In order to make the area of the frame region as small as possible, it is necessary to arrange the transfer electrode 7 as close to the seal material 5 as possible. Therefore, in the present embodiment, the sealing material 5 is formed so as to ride on a part of the transfer electrode 7.

  FIG. 3 shows a cross-sectional structure in the vicinity of the transfer electrode 7 formation position. The array substrate 1 and the counter substrate 2 are bonded to each other with a predetermined interval by bonding with the seal material 5 with the spacer material 8 interposed therebetween. The counter electrode 9 formed on the surface of the counter electrode 2 is in contact with the conductive particles 10 placed on the transfer electrode 7, and as a result, the counter electrode 9 and the transfer electrode 7 are electrically connected. .

  Here, as described above, the transfer electrode 7 is disposed in the vicinity of the seal material 5, and the seal material 5 is formed so as to run over a part thereof. The transfer electrode 7 is made of metal, and its adhesion to the sealing material 5 is greatly inferior to that of the array substrate 1. Therefore, at the position where the transfer electrode 7 is formed, the contact width of the sealing material 5 with respect to the array substrate 1 is greatly reduced, and the array substrate 1 and the counter substrate 2 are likely to be peeled off. It has become.

  FIG. 4A schematically shows a contact state of the sealing material 5 with respect to the array substrate 1 in a portion where the transfer electrode 7 is not arranged, and FIG. 4B shows that the transfer electrode 7 is arranged. The contact state with respect to the array board | substrate 1 of the sealing material 5 in a part is shown typically. Compared to the bonding width W1 of the sealing material 5 to the array substrate 1 in the former, the bonding width W2 of the sealing material 5 to the array substrate 1 in the latter is smaller, leading to a substantial reduction in the bonding area.

  Therefore, in the present embodiment, at the position where the transfer electrode 7 is formed, the shape of the protective film 6 formed of transparent resin is changed, and a part of the protective film 6 is expanded to form an expanded portion 6a. The sealing material 5 is formed so as to ride on the portion 6a. The protective film 6 formed of a transparent resin has much higher adhesion to the sealing material 5 than the metal transfer electrode 7 described above. Therefore, by bringing the extended portion 6 a of the protective film 6 into contact with the sealing material 5, the substantial adhesion area (adhesion width) of the sealing material 5 is expanded.

  As described above, in the liquid crystal display device of this embodiment, the shape of the protective film 6 formed of the transparent resin is changed in the vicinity of the position where the transfer electrode 7 is formed, and the protective film 6 that has been formed only in the display region H until now. Is extended in accordance with the position where the transfer electrode 7 is formed, so that the seal area of the seal material 5 can be expanded to the same extent or more as the seal area of the peripheral region in the transfer electrode 7 formation portion. The substrate peeling of the counter substrate 2 can be prevented. The peeling of the substrate significantly reduces the quality and reliability of the liquid crystal display device. However, by adopting the above structure, it is possible to provide a liquid crystal display device with excellent quality and high reliability.

  In addition, it cannot be overemphasized that the liquid crystal display device of this invention is not limited to the above-mentioned embodiment, A various change is possible in the range which does not deviate from the summary of this invention. For example, in the above-described embodiment, the transfer electrode 7 is a pad-shaped electrode, and the conductive particles 10 are placed on the transfer electrode 7 so as to be electrically connected to the counter electrode 9, but the transfer electrode is a columnar electrode. It is also possible to form. When the transfer electrode is a columnar electrode, it is composed of a columnar portion and a pad portion that is slightly larger than the columnar portion. However, even in the liquid crystal display device in which the seal material 5 is formed on the pad portion, By adopting the same configuration as that of the embodiment, it is possible to secure a bonding area by the sealing material 5 and prevent the array substrate 1 and the counter substrate 2 from peeling off.

  In the previous embodiment, the substantial adhesion area of the sealing material 5 is expanded by expanding the protective film 6 made of a transparent resin formed in the display region H. Instead, the adhesion area can be increased by expanding the gate insulating film, the interlayer insulating film, and the like of the pixel transistor formed in the display region H and bringing them into contact with the sealing material 5.

  FIG. 5 shows an embodiment in which a gate insulating film, an interlayer insulating film, and the like are expanded. In the present embodiment, a thin film transistor 11 that functions as a pixel transistor is formed in the display region H of the array substrate 1.

  The thin film transistor 11 is directly formed on the array substrate 1 using, for example, polysilicon as an active layer. That is, in the thin film transistor 11, a polycrystalline semiconductor layer (polysilicon layer) 12 is formed on the array substrate 1 through an undercoat layer formed as necessary, and the polycrystalline semiconductor layer 12 is formed as an active layer (channel). Layer).

  The polycrystalline semiconductor layer 12 is formed, for example, by annealing amorphous silicon (a-Si) formed by a plasma CVD method and then crystallizing it by laser irradiation or the like. The polycrystalline semiconductor layer 12 is element-isolated into an island shape by etching. For example, in the case of an n-channel type thin film transistor, a source region 12A and a drain region 12B are formed in each polycrystalline semiconductor layer 12 by impurity implantation, and LDD regions (low-concentration impurity diffusion regions) 12C and 12D are further formed. Is formed.

  A gate electrode 14 is formed on the channel of the polycrystalline semiconductor layer 12 with a gate insulating film 13 interposed therebetween. Further, a wiring 15 connecting the source region 12A or the drain region 12B of the thin film transistor 11 to another circuit is first. It is formed via an interlayer insulating film 16. A second interlayer insulating film 17 is formed on the wiring 15.

  In the array substrate 1 having such a configuration, the gate insulating film 13, the first interlayer insulating film 16, and the second interlayer insulating film 17 are expanded at the position where the transfer electrode 7 is formed, and the expanded portion is brought into contact with the sealing material 5. It is possible to obtain the same effect (enlargement of the substantial bonding area of the sealing material 5).

It is a schematic perspective view which shows the structural example of the liquid crystal display panel integrated in a liquid crystal display device. It is a typical top view which shows an example of seal pattern arrangement | positioning. It is a principal part schematic sectional drawing of the transfer electrode vicinity. It is a schematic diagram which shows the contact state with respect to the array substrate of a sealing material, (a) is a schematic diagram of the cross section in the position where the transfer electrode is not arrange | positioned, (b) is a schematic diagram of the cross section in the position where the transfer electrode is arrange | positioned. It is. It is a principal part schematic sectional drawing which shows embodiment which expanded the gate insulating film and the interlayer insulation film.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Array substrate, 2 Counter substrate, 5 Sealing material, 6 Protective film, 6a Expansion part, 7 Transfer electrode, 9 Counter electrode, 11 Thin-film transistor, 12 Polycrystalline semiconductor layer, 13 Gate insulating film, 14 Gate electrode, 15 Wiring, 16 First interlayer insulating film, 17 Second interlayer insulating film

Claims (4)

A liquid crystal display device in which an array substrate and a counter substrate are bonded by a sealing material applied on the array substrate, and liquid crystal is sealed between the array substrate and the counter substrate,
The coating film formed so as to cover the display area of the array substrate is extended so as to be in contact with the sealing material at a position where the sealing material is in contact with the transfer electrode provided in the peripheral area of the array substrate. Liquid crystal display device.   2. The liquid crystal display device according to claim 1, wherein the coating film is a protective film or an insulating film formed in the display region.   The liquid crystal display device according to claim 1, wherein the coating film is formed of a transparent resin.   4. The liquid crystal display device according to claim 1, wherein the sealing material is formed so as to ride on the expanded coating film, and an adhesion area is expanded. 5.

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