JP3238223B2 - Liquid crystal display device and display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device having a display surface curved using a flexible substrate.

[0002]

2. Description of the Related Art In recent years, display devices using an active matrix type liquid crystal display have been used for large-capacity information display applications such as personal computers, word processors, various OA terminal devices, and TV image displays. There is a demand for higher quality display. Various types of switching elements of the active matrix type liquid crystal display have been put into practical use, and typically, there are a TFT type using a thin film transistor and an MIM type using a non-linear resistance element. Among them, the two-terminal type MIM, that is, the nonlinear resistance element composed of metal-insulating film-metal has been widely used because of its simple structure and easy manufacture. Such MI
The basic structure and manufacturing method of an M-type nonlinear resistance element are disclosed in Japanese Patent Application Laid-Open Nos. 55-161273 and 58-17832.
No. 0 publication. That is, as shown in FIG. 7, a metal, for example, a Ta film 3 is formed on a glass substrate 1 by a sputtering method or an evaporation method, and is patterned by a photolithography method, and a wiring extending in one direction and one electrode of the MIM are formed. Is formed. Next, the Ta film 3 is formed by, for example, anodizing in an aqueous citric acid solution to form an oxide film 5. Further, as another electrode of the MIM, for example, a Cr film 6 is similarly patterned by photolithography,
The MIM element is completed. Further, a transparent electrode 8 for pixel display is formed so as to overlap a part of the Cr film 6. A transparent electrode extending in one direction is formed on the other substrate (not shown), and the electrodes extending in one direction of the two substrates are opposed to each other so as to be orthogonal to each other. A liquid crystal layer is injected. The MIM element as a switching element is arranged corresponding to the intersection. Since a glass plate is usually used as a substrate of such an active matrix type liquid crystal display, the display surface is flat.

[0003]

In recent years, as active matrix type liquid crystal displays have been widely used in various electronic devices, there has been a problem with the shape and design of electronic devices or the problem of space-saving. Liquid crystal displays have been required. For such a curved surface display,
In a conventional glass substrate, glass has to be formed into a curved surface in advance, but it is not practical from a manufacturing point of view, such as forming a switching element on a curved substrate with high accuracy and keeping the distance between substrates constant.

Therefore, it is conceivable to use a flexible substrate. In a liquid crystal display which is an optical display, since it is required to be optically isotropic, a biaxially stretched polyester film (PET) or the like cannot be used. A uniaxially stretched polyester film (PET) or polyether sulfone (PES) can be used so that the optical axis does not change in the plane of the film. For example, PES has a glass transition point of 2
It does not change at a high temperature of more than 00 ° C and continuous 180 ° C, is transparent and has excellent chemical resistance.
Can be used. However, for example, a metal wiring that extends in one direction with a thickness of several thousand angstroms and a width of several tens of μm and a length of several cm or more, which is required for an MIM element, is used as a switching element. When it is formed on the upper surface and bent in the direction in which the metal wiring extends, peeling occurs in the longitudinal direction of the metal wiring with a radius of curvature of several mm to several cm. When a similar pattern was formed with a transparent electrode (ITO) and was similarly curved, it adhered well and did not peel. That is, if the metal wiring extending in one direction is bent in the extending direction, the metal wiring is frequently peeled off. Moreover, this was more remarkable for a large screen and a high definition.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has a high performance using a switching element having no electrode peeling even in a large screen and a high definition display in which a display surface is curved using a flexible substrate. It is an object of the present invention to provide a liquid crystal display device.

[0006]

According to the present invention, there is provided a first flexible substrate having a surface on which wiring electrodes extending in a first direction are formed, and a second direction orthogonal to the first direction. A second flexible substrate having a wiring electrode extending on the surface thereof, and a transparent electrode in which the wiring electrodes of the first flexible substrate and the second flexible substrate are arranged so as to be orthogonal to each other. A liquid crystal display device comprising at least a switching element formed in a portion orthogonal to the liquid crystal layer and a liquid crystal layer sandwiched between the first flexible substrate and the second flexible substrate disposed opposite to each other. When bending the flexible substrate, make the bending direction match the substantially rectangular short side direction of the switching element, or make the bending direction match the extending direction of the wiring electrode having the larger line width. That the switching element is formed. The center of curvature of the curved sexual substrate by allowed to opposite, it is to achieve the above object.

[0007]

In the active matrix type liquid crystal display device, stripe-shaped wiring electrodes are formed on the upper and lower substrates so as to be orthogonal to each other in order to address pixels. The switching elements are formed at corresponding portions of the pair of wiring electrodes of the two substrates that intersect at right angles. Now, when bending the liquid crystal display device along one of the wiring electrodes of the two substrates,
If it bends along the direction that is strong against bending peeling, the effect on peeling failure is high. For example, in the case of a MIM element, Ta serving as a metal electrode on the substrate side has a large internal stress of the metal film,
And the width is narrow for the thickness. For this reason, as shown in FIG. 1, it is more preferable to bend along the arrow 10 in the direction of the transparent electrode (ITO) pattern 15 on the opposing substrate, along the arrow 11 in the direction of the wiring electrode 3 on the array substrate. Peeling is less than it does. Actually, in the former case, the radius of curvature is 10 mm
Does not occur, whereas the latter has a radius of curvature of 50 mm.
Peeled off.

[0008] Further, as shown in FIG.
When the width W1 of the Ta electrode 3 was set to 6 μm and the width W2 of the Ti electrode 6 was set to 4 μm, the curvature of the Ti electrode 6 along the direction of the arrow 13 which is the wiring direction was And the Ta electrode 3 was overwhelmingly easily peeled as compared with the curvature along the direction of the arrow 12 which is the wiring direction.
Further, when the substrate is bent, divergent stress acts on all the electrodes on the substrate on the side of the center of curvature of the curvature in the bending direction, and peeling is likely to occur. If cracks occur and electrical continuity is impaired even without peeling, it is a fatal defect as a liquid crystal display device. On the other hand, compressive stress acts on all the electrodes along the bending direction on the substrate on the side opposite to the curvature center of the curvature, and therefore, the electrodes are more likely to peel off than the electrodes along the bending direction on the substrate near the center of the curvature. The risk of cracking is much less.

As a result, it is necessary to appropriately select and design the pattern directions of the wiring electrodes and the switching elements in advance with respect to the bending direction of the substrate. In other words, the portion constituting the switching element formed on one substrate is substantially rectangular, and the direction along the short side of the rectangular shape may be matched with the bending direction. In addition, the direction along the wiring direction with the wider electrode width of the wiring electrodes of the two substrates may be matched with the bending direction. Further, the substrate on which the switching element is formed is preferably disposed on the side opposite to the center of curvature of the curve.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to FIG.
An example in which an IM is applied will be described in detail with reference to FIGS. First, for example, as shown in FIG.
A thin film 3 of 3000 Å of Ta is formed by a sputtering method on a polyethersulfone film substrate 1 having a thickness of 0.2 mm and a silicon dioxide undercoat film formed on the surface thereof by a low-temperature sputtering. Next, after applying a positive type photoresist film on the entire surface of the thin film 3, it is exposed using a photomask and developed to form a resist pattern 4a. Subsequently, the thin film 3 is etched by a chemical dry etching method. Here, etching is performed in plasma in which CF4 and O2 gases are mixed in equal amounts, and a tapered shape is formed at an edge portion around the pattern. Subsequently, as shown in FIG.
After removing the resist pattern 4a, the thin film pattern 3 made of Ta is used as an anode, and a platinum mesh plate is used as a cathode.
Anodization is performed in an electrolytic solution of a 1% by weight aqueous solution of ammonium borate, and an insulating layer 5 is formed to a desired thickness on the surface of the thin film pattern 3 made of Ta by controlling the voltage. For example, when a voltage of 48 V was applied, an insulator layer of about 800 Å was obtained. At Ta which is exposed to the electrolyte, the metal having a thickness of about 320 Å is changed to tantalum pentoxide having a thickness of about 800 Å. Next, as shown in FIG.
A thin film 6 made of 200 angstroms of Ti is formed by a sputtering method. On the thin film 6 made of Ti, a positive-type photoresist film is again applied on the entire surface, and then exposed using a photomask and developed to form a resist pattern 4.
b is formed. Subsequently, 9 g of ethylenediamine tetraacetic acid, 400 cc of water, 216 cc of hydrogen peroxide and 30 ml of ammonia water were mixed at a ratio of 30 g, and the thin film 6 made of Ti was etched at room temperature to remove the remaining resist pattern 4 b. I do. Thereby, MIM
An upper electrode on the far side of the device is formed on the substrate. Next, as shown in FIG. 3D, a transparent conductive film 7 made of ITO having a thickness of about 1000 Å is formed on the entire surface by sputtering. A positive-type photoresist film is again applied on the entire surface of the transparent conductive film 7 and then exposed using a photomask and developed to form a resist pattern 4c. Subsequently, water, hydrochloric acid and nitric acid were mixed at a volume ratio of 1: 1: 0.
The mixture was mixed at a ratio of 1 and etched with an etchant heated to 30 ° C. to form an ITO pattern 8. Thus, an array substrate including the MIM element 9 is formed as shown in FIGS.

Next, an ITO pattern electrode 15 as a wiring electrode extending in one direction is formed on the same polyether sulfone film substrate used for the array substrate by the same method as described above, and a counter substrate is formed. . Both substrates prepared as described above are coated with an alignment film made of a polyimide resin, baked, and subjected to a rubbing process in one direction to regulate liquid crystal alignment. Next, the wiring electrodes of both substrates are opposed to each other, the wiring electrodes are orthogonal to each other so as to form 90 degrees, and the distance between the two substrates is maintained at 5 to 10 μm, and a part of the liquid crystal injection port is filled with an adhesive around the substrates. And seal (not shown). Then, for example, a TN type liquid crystal material is injected from the liquid crystal injection port by a vacuum injection method, and finally, the liquid crystal injection port is also sealed. Furthermore, a TN type active matrix type liquid crystal display device having a 90-degree twist is completed by mounting polarizing plates on the outer sides of both substrates so as to be orthogonal to each other by 90 degrees along the rubbing direction.

Next, the bending direction of the substrate of the liquid crystal display device will be described with reference to FIGS. FIG.
FIG. 6 shows the arrangement relationship between pixels and a counter electrode on a counter substrate in an overlapping manner. In FIG. 5, the MIM element section 9 indicated by hatching
Has a rectangular shape with a width W1 in the long side direction of 6 μm and a width W2 in the short side direction of 4 μm. Also, while the line width W3 of Ta pattern 3 is a wiring electrode is 20 [mu] m, line width W4 of the ITO pattern 15 is a wiring electrode on the counter substrate is 250 [mu] m, and Ta pattern 3 and the ITO pattern 15 One functions as a scanning signal supply line, and the other functions as a data signal supply line.

FIG. 6A shows a cross section along the line AA of FIG. 5, and FIG. 6B shows a cross section along the line BB of FIG. 5, respectively. That is, while the substrate is curved with a radius of curvature of about 30 cm in the short side direction of the MIM element 9 and in the direction parallel to the AA line along the wider ITO pattern 15 of the wiring electrodes, The direction along the BB line is flat. Further, the substrate 1 on which the MIM element is formed is a counter substrate 2
Is located on the opposite side to the center of curvature of the curve.

When the liquid crystal display device of this embodiment was driven, no defect was found due to electrical conduction failure due to peeling or cracking of the wiring electrode and the MIM element. In the above embodiment, the switching element is MI
Although the active matrix type liquid crystal display device to which the M element is applied has been described, the present invention is not limited to this and can be applied to an active matrix type liquid crystal display device using a thin film transistor.

[0015]

As described above, the liquid crystal display device having a curved display surface obtained by bending a flexible substrate according to the present invention,
Curving in the direction along the short side of the substantially rectangular switching element, and / or curving in the direction along the wide wiring electrode among the opposed wiring electrodes,
And / or by positioning the substrate on which the switching elements are formed on the side opposite to the center of curvature of the curved substrate, i.e., by bending the electrode pattern on the substrate in a direction strong against bending stress, the wiring electrodes and the switching elements are formed. The present invention is effective for a highly reliable liquid crystal display device for displaying a curved surface, which is free from defects due to poor electrical conduction due to electrode peeling or cracks.

[Brief description of the drawings]

FIG. 1 is a schematic diagram for explaining the operation of the present invention.

FIG. 2 is a schematic diagram for explaining the operation of the present invention.

FIG. 3 is an exploded view for explaining a manufacturing process according to the embodiment of the present invention.

FIG. 4 is a plan view showing the plane of FIG. 3;

FIG. 5 is a plan view showing an electrode arrangement according to the embodiment of the present invention.

FIG. 6 is a sectional view showing a section taken along line AA and line BB in FIG. 5;

FIG. 7 is a sectional view showing the structure of a MIM element as a switching element.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Substrate 2 ... Substrate 3 ... Ta electrode 5 ... Insulator layer 6 ... Ti electrode 8 ... ITO electrode 9 ... MIM element 14 ... Liquid crystal layer 15 ...・ ITO electrode

Claims (5)

(57) [Claims] 1. A first flexible substrate having a surface on which a wiring electrode extending in a first direction is formed, and a wiring electrode extending in a second direction orthogonal to the first direction on a surface. The formed second flexible substrate, and the wiring electrodes of the first flexible substrate and the second flexible substrate are disposed so as to face each other so as to be orthogonal to each other, and the wiring electrodes are formed in portions where the wiring electrodes are orthogonal to each other. A liquid crystal display device comprising at least a substantially rectangular switching element, and a liquid crystal layer sandwiched between the first and second flexible substrates opposed to each other, The two flexible substrates are arranged in a curved manner along one of the first direction and the second direction, and the curved direction coincides with the short side direction on the rectangle of the switching element. Liquid crystal display device. 2. A first flexible substrate having a surface on which a wiring electrode extending in a first direction is formed, and a wiring electrode extending in a second direction orthogonal to the first direction on a surface. The formed second flexible substrate, and the wiring electrodes of the first flexible substrate and the second flexible substrate are disposed so as to face each other so as to be orthogonal to each other, and the wiring electrodes are formed in portions where the wiring electrodes are orthogonal to each other. In a liquid crystal display device including at least a switching element and a liquid crystal layer sandwiched between the first and second flexible substrates opposed to each other, the liquid crystal display device extends in the first direction. The line width of the wiring electrode to be formed is different from the line width of the wiring electrode extending in the second direction, and the two flexible substrates are arranged in any one of the first direction and the second direction. And the bending direction is the same as the extending direction of the wiring electrode having the larger line width. A liquid crystal display device characterized by: 3. A first flexible substrate having a surface on which a wiring electrode extending in a first direction is formed, and a wiring electrode extending in a second direction orthogonal to the first direction on a surface. The formed second flexible substrate, and the wiring electrodes of the first flexible substrate and the second flexible substrate are disposed so as to face each other so as to be orthogonal to each other, and the wiring electrodes are formed in portions where the wiring electrodes are orthogonal to each other. In a liquid crystal display device comprising at least a switching element and a liquid crystal layer sandwiched between the first flexible substrate and the second flexible substrate disposed opposite to each other, the two flexible substrates The substrate is curvedly arranged along any one of the first direction and the second direction, and the flexible substrate on which the switching element is formed is located on a side opposite to the curved center of curvature. Characteristic liquid crystal display device. 4. A first flexible substrate, a second flexible substrate arranged opposite to the first flexible substrate, and a first flexible substrate arranged on the first flexible substrate. A wiring electrode extending in the direction of, a substantially rectangular switching element connected to the wiring electrode, and a pixel connected to the switching element.
And wherein the two flexible substrates are arranged in a curved manner, and the curved direction thereof coincides with the rectangular short side direction of the switching element. apparatus. 5. A first flexible substrate, a second flexible substrate arranged opposite to the first flexible substrate, and a first flexible substrate arranged on the first flexible substrate. And a switching element connected to the wiring electrode, and a pixel connected to the switching element, wherein the two flexible substrates are curved. Is disposed, the flexible substrate on which the switching element is formed,
A display device, wherein the display device is located on a side opposite to the curved center of curvature.