JPH07301789A - Liquid crystal display device and its production - Google Patents

Abstract

PURPOSE:To obviate the occurrence of a gap defect by a bending distortion of a liquid crystal display device formed to a curved surface shape. CONSTITUTION:A lower resin substrate 1 and an upper resin substrate 2 having the larger coefft. of thermal expansion than the coefft. of thermal expansion thereof are superposed on each other via a sealing material 8. Next, both resin substrates 1, 2 are thermocompression bonded from both front and rear surfaces to stick the resin substrates 1, 2 to each other and simultaneously, the resin substrates 1, 2 are thermally expanded. In such a case, the lower resin substrate 1 having the smaller coefft. of thermal expansion elongates to the smaller extent and the upper resin substrate 2 having the larger coefft. of thermal expansion elongates larger and eventually, the resin substrates 1, 2 curve in such a manner that their front surface side crowns. Two sheets of the resin substrates 1, 2 are formed to the curved surface shape by utilizing a difference in their coeffts. of thermal expansion in such a manner and, therefore, the gap defect by the bending distortion more hardly occurs than in the case of forming of the curved liquid crystal display device by forcibly bending the flat planar liquid crystal display device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a curved liquid crystal display device and a method for manufacturing the same.

[0002]

2. Description of the Related Art Some liquid crystal display devices have a curved surface. As a conventional manufacturing method for such a liquid crystal display device, first, two resin substrates are attached with a sealing material, and liquid crystal is sealed between both resin substrates inside the sealing material to form a flat liquid crystal display device. There is one in which the liquid crystal display device is formed once and then forcibly bent along a curved surface member having a curved surface of a predetermined curvature.

[0003]

However, in the conventional method of manufacturing a liquid crystal display device as described above, since the flat plate-shaped liquid crystal display device is forcibly bent along the curved surface member, the central portion of the display portion is mainly used. There is a problem in that a gap defect occurs due to bending strain, and as a result, a display defect such as discoloration occurs. An object of the present invention is to provide a liquid crystal display device in which a gap defect due to bending strain is unlikely to occur and a method for manufacturing the same.

[0004]

In a liquid crystal display device according to the present invention, two resin substrates having different thermal expansion coefficients are bonded together with a sealing material, and a curved surface is formed due to the difference in the thermal expansion coefficient between the two resin substrates. It was formed. In the method for manufacturing a liquid crystal display device according to the present invention, two resin substrates having different thermal expansion coefficients are superposed on each other via a sealing material, thermocompression-bonded to each other, and the resin substrates are bonded together by the sealing material. The two resin substrates are thermally expanded and formed into a curved surface due to the difference in thermal expansion coefficient between the two resin substrates.

[0005]

According to the present invention, since the liquid crystal display device is formed in a curved shape by utilizing the difference in the coefficient of thermal expansion of the two resin substrates, the flat plate liquid crystal display device is forcibly bent and curved. As compared with the case of forming in the above, there is no possibility that a gap defect due to bending strain will occur.

[0006]

FIG. 1 shows an embodiment of a liquid crystal display device according to the present invention. This liquid crystal display device includes two resin substrates 1 and 2 having different thermal expansion coefficients, that is, a lower resin substrate 1 and an upper resin substrate 2 having a higher thermal expansion coefficient. The lower resin substrate 1 is made of a resin material such as polyethylene terephthalate (coefficient of thermal expansion: 5.5 [× 10 ⁻⁵ / ° C.]), and the upper resin substrate 2 is polyarylate (coefficient of thermal expansion: 6. 1 to 6.3 [× 10 ⁻⁵ / ° C.]) and the like. The transparent electrodes 3 and 4 and the alignment film 5 are formed on the surfaces of the resin substrates 1 and 2 which face each other.
6 is formed. The two resin substrates 1 and 2 are bonded together by a sealing material 8 made of epoxy resin or the like with a spacer 7 made of particles of glass or resin having a certain size interposed therebetween, and the two resin substrates 1 and 2 are heat-treated. Due to the difference in expansion coefficient, the resin substrates 1 and 2 are curved so that the upper surfaces thereof are convex. A liquid crystal enclosed area is formed between the resin substrates 1 and 2 inside the sealing material 8, and a liquid crystal 9 is enclosed in the liquid crystal enclosed area, whereby a curved display portion 10 is formed.

Next, an embodiment of a method of manufacturing the liquid crystal display device will be described with reference to FIGS.
First, as shown in FIG. 2, a lower resin substrate 1 made of a resin material such as polyethylene terephthalate (coefficient of thermal expansion: 5.5 [× 10 ⁻⁵ / ° C.]) is prepared. The lower transparent electrode 3 made of ITO or the like is formed on the upper surface of the lower resin substrate 1.
Is patterned, and a lower alignment film 5 made of polyimide or the like subjected to a predetermined alignment treatment is formed at a predetermined position on the upper surface of the lower resin substrate 1 including the lower transparent electrode 3. Spacers 7 are arranged on the upper surface of the lower alignment film 5 by spraying or the like.

Next, as shown in FIG. 3, polyarylate having a coefficient of thermal expansion larger than that of the lower resin substrate 1 (coefficient of thermal expansion: 6.1 to 6.3 [× 10 ^-5 / ° C.]). An upper resin substrate 2 made of a resin material such as is prepared. The upper transparent electrode 4 made of ITO or the like is formed on the lower surface of the upper resin substrate 2.
Is patterned, and an upper alignment film 6 made of polyimide or the like subjected to a predetermined alignment treatment is formed at a predetermined position on the lower surface of the upper resin substrate 2 including the upper transparent electrode 4. Upper resin substrate 2 around the alignment film 6
A sealing material 8 made of a thermosetting resin such as an epoxy resin having a liquid crystal inlet (not shown) is formed on the lower surface of the sheet by printing or the like. Next, the upper resin substrate 2 is placed in alignment with the upper position of the lower resin substrate 1.

Next, as shown in FIG. 4, both resin substrates 1 and 2 are superposed on each other with a sealing material 8 interposed therebetween. Next, when the two resin substrates 1 and 2 are thermocompression bonded from both upper and lower surfaces, the sealing material 8 is formed.
Is cured, and the two resin substrates 1 and 2 are bonded together by the cured sealing material 8. At the time of this thermocompression bonding, both resin substrates 1 and 2 are thermally expanded according to their respective thermal expansion coefficients, and are still in a state of being thermally expanded even if they are gradually cooled by leaving them at room temperature. As a result, the upper resin substrate 2 having a large coefficient of thermal expansion expands a lot, and the lower resin substrate 1 having a small coefficient of thermal expansion expands a little.
Have a curved surface whose upper surface is convex. Next, the liquid crystal 9 is injected into the liquid crystal enclosing region between the resin substrates 1 and 2 inside the seal material 8 through the liquid crystal injection port formed in the seal material 8, and then the liquid crystal injection port is sealed with the sealing material ( When sealed with (not shown), as shown in FIG. 1, the liquid crystal display device of this embodiment in which the display unit 10 has a curved shape is manufactured.

As described above, since the liquid crystal display device is formed in a curved shape by utilizing the difference in the coefficient of thermal expansion between the two resin substrates 1 and 2, the flat plate liquid crystal display device is forcibly bent and curved. As compared with the case of forming the strip-like shape, there is no possibility of causing a gap defect due to bending strain, and therefore, there is no possibility of causing a display defect such as discoloration. Further, if the coefficient of thermal expansion of each of the resin substrates 1 and 2 is appropriately selected, the curved surface of the liquid crystal display device can have a desired curvature.

In the above embodiment, the coefficient of thermal expansion of the upper resin substrate 2 is set to be higher than that of the lower resin substrate 1, but the present invention is not limited to this. The coefficient of thermal expansion of the substrate 1 made of resin may be made larger than the coefficient of thermal expansion of the resin substrate 2 on the upper side, and the point is that the coefficients of thermal expansion of the resin substrates 1 and 2 are different from each other. Further, in the above embodiment, the sealing material 8 is the thermosetting type, but the sealing material 8 is not limited to this, and a photocuring type may be used, for example. In this case, the sealing material 8 is cured by irradiating light and then heated in an oven or the like to form the both resin substrates 1 and 2 in a curved shape.

[0012]

As described above, according to the present invention, since the liquid crystal display device is formed in a curved shape by utilizing the difference in the coefficient of thermal expansion of the two resin substrates, the flat plate liquid crystal display device. As compared with the case where the sheet is forcibly bent to be formed into a curved surface, there is no possibility of causing a gap defect due to bending distortion, and therefore, there is no possibility of causing a display defect such as discoloration.

[Brief description of drawings]

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

FIG. 2 is a cross-sectional view showing a state in which spacers are scattered on the upper surface of the alignment film of the lower resin substrate when manufacturing the liquid crystal display device.

FIG. 3 is a cross-sectional view showing a state in which an upper resin substrate is placed above a lower resin substrate in manufacturing the same liquid crystal display device.

FIG. 4 is a cross-sectional view of a state in which both resin substrates are overlapped with each other with a sealing material in the manufacturing of the liquid crystal display device.

[Explanation of symbols]

 1, 2 Resin substrate 3, 4 Transparent electrode 5, 6 Alignment film 7 Spacer 8 Sealing material 9 Liquid crystal 10 Display section

Claims (2)

[Claims] 1. A liquid crystal display device, wherein two resin substrates having different thermal expansion coefficients are bonded to each other with a sealing material, and the resin substrates are formed into a curved surface due to a difference in thermal expansion coefficient between the two resin substrates. 2. Two resin substrates having different thermal expansion coefficients are superposed on each other via a sealing material, thermocompression-bonded to bond the both resin substrates together with the sealing material, and heat the two resin substrates together. A method for manufacturing a liquid crystal display device, which comprises expanding and forming a curved surface according to a difference in coefficient of thermal expansion between the two resin substrates.