JPS60243632A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To decrease the material strain of a pair of upper and lower transparent substrates arising from the bonding force from the outside by forming plural grooves perpendicular to the bending direction on the surfaces of said substrates and the side opposite from the surfaces facing a liquid crystal. CONSTITUTION:The plural continuous pulse-like grooves 15 extending in the transverse direction are formed on the outside flank of the upper substrate 11 and the similar grooves 15 are also formed on the outside flank of the lower substrate 12. The grooves 15 are formed in approximately parallel with each other. The substrates 11 and 12 are joined in such a manner that the grooves are approximately paralleled in the joined state. The tensile force and shrinkage force to each substrate are relieved by the grooves 15 and the tension generated near the outside flank within each substrate is decreased. The stress in the substrates is thus decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a liquid crystal display device in which a pair of transparent substrates facing each other with a liquid crystal interposed therebetween are made of an organic material.

BACKGROUND ART Such a liquid crystal display device has the advantage that the transparent substrate has greater mechanical strength than a liquid crystal display device made of an inorganic material, is flexible, and is also lightweight. There is. Therefore, such liquid crystal display devices are suitably used in thin calculators and the like. A typical prior art example of such a liquid crystal display device is shown in FIG. The pair of upper and lower substrates 2 and 3 of this liquid crystal display device 1 is formed into a flat plate shape. Therefore, when a bending moment is applied to both ends due to an external load, the upper and lower substrates 2 and 3 are bent due to bending stress.
is curved as shown in FIG. 2, and the first equation is satisfied.

r4) r3) r2) rl (1) Here, rl indicates the radius of curvature of the outer surface of the lower substrate 3, r2 indicates the radius of curvature of the inner surface of the lower substrate 3, and r3 indicates the radius of curvature of the inner surface of the upper substrate 2. The radius of curvature of the side surface is shown, and r4 is the radius of curvature of the outer surface of the upper substrate 2. The mutual difference between the radii of curvature r2 and r3 is, for example, 5 to 20 μm. In the state where the upper and lower substrates 2.3 are curved, as shown in FIG. A tensile force f1 and a contraction force f2 act on the substrates 2 and 3 due to the difference between the contraction stress δ2 and the contraction stress δ2.

Therefore, the cell gap 4 formed by the upper and lower substrates 2.degree. 3 is extremely different between the center and both ends. As a result, deterioration of electro-optical characteristics such as non-uniformity of response time and non-uniformity of contrast ratio occurs. Further, for example, in a normal area, a gray tone is exhibited, but in an extremely thin area of the cell gap 4, color unevenness occurs in the form of interference colors such as red, green, yellow, etc., and the product value is extremely reduced. Therefore, the conventional liquid crystal display device 1 has the disadvantage that it cannot be bent with a small curvature, which limits the ability to bend, which is one of the characteristics of plastic liquid crystal display devices.

Purpose An object of the present invention is to provide a liquid crystal display device in which material distortion of upper and lower substrates due to external bending force is reduced as much as possible.

Embodiment FIG. 4 is a perspective view of an embodiment of the present invention, and FIG. 5 is a longitudinal sectional view of FIG. 4. The liquid crystal display device 10 has an upper substrate 11
, a lower substrate 12, a transparent electrode 13 formed on the inner surface of each substrate 11 and 12, and a liquid crystal 14 interposed between the substrates 11 and 12. A plurality of continuous pulse-shaped grooves 15 extending in the width direction are formed on the outer surface of the upper substrate 11. A similar groove 15 is also formed on the outer surface of the lower substrate 12. The grooves 15 are formed substantially parallel to each other, and when the substrates 11 and 12 are combined, they are joined so as to be parallel to each other. The substrates 11 and 12 are made of the same material as the polarizing plate, and in this embodiment also serve as the polarizing plate.

The shape of the groove 15 formed in the substrate 11, 12 is pulse-like, the depth d is selected to be 1 to 20 μm, and the width of the groove 15 is selected to be 1 to 50 μm. Furthermore, groove 15 and groove 15
The width β of the convex portion 16 formed by is selected so as to satisfy β>α. When the liquid crystal display device 1o constructed in this manner is bent, tensile stress δ3 and shrinkage stress δ4 act on the substrates 11 and 12, as shown in FIG.

At this time, the effect of the stress on the outer surface of the substrate 11.12 due to the groove 15 is as shown in FIG.

Accordingly, the tensile force F1 and the contraction force F2 are relieved by the grooves 15, and the tension generated near the outer surface within each substrate 11.12 is reduced, resulting in less stress within the substrate. Therefore, the relative difference between the tensile force F1 and the contractile force F2 on the opposing surfaces of the substrates 11, 12 is smaller than in the prior art.

Therefore, the radius of curvature at the outer surface of the substrate 12 is R1,
When the radius of curvature on the inner surface of the substrate 12 is R2, the radius of curvature on the inner surface of the substrate 11 is R3, and the radius of curvature on the outer surface of the substrate 11 is R4, the second equation is satisfied.

rl〉R1, r2. >R2, r3. >R3゜r4)R4
...(2) Note that R1-R4 satisfies R4>R3>R2>R1. In this way, it is possible to make the radius of curvature smaller than in the past. This makes it possible to reduce the bending angle and reduce as much as possible the deterioration of electro-optical characteristics and the extreme deterioration of commercial value due to color unevenness in the form of interference colors.

Although in the previous embodiment the substrates 11.12 acted as polarizers, in other embodiments the upper and lower substrates -1G11 1
Qr-1 Ryobanji n 111 b-Ha A Shijusen j N-L 4 1 μF -1 Even if the polarizing plate is made of a diether type polymer or the like and formed on the substrate via an adhesive. good. In this case, a highly adhesive adhesive such as an acrylic adhesive is used, and as a result, shear deformation occurs to alleviate the tension and contraction force generated between the polarizing plate and the substrate 11, 12, so the bending angle must be adjusted. It is possible to make it smaller than the conventional one.

Although the grooves 15 were formed in the upper and lower substrates 11 and 12 in the embodiments described above, they may be formed only in either the upper substrate 11 or the lower substrate 12. Furthermore, although the grooves 15 have a pulse shape, they may have other shapes such as a wave shape. Furthermore, the grooves 15 may extend in the width direction and the length direction of the substrate 11.12 and intersect with each other.

Effects As described above, according to the present invention, at least one of a pair of transparent substrates made of an organic material facing each other with a liquid crystal interposed therebetween has the aforementioned r! - Since we have formed multiple grooves perpendicular to the bending direction on the opposite side of the product, it is possible to reduce as much as possible the material distortion of the upper and lower substrates caused by external bending forces. becomes.

Therefore, the bending angle at which the failure mode occurs can be made much smaller than in the past. Therefore, the liquid crystal display device of the present invention can effectively exhibit the characteristic of being bendable.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a typical prior art liquid crystal display device 1, FIG. 2 is a diagram showing the radius of curvature that occurs when the liquid crystal display device 1 is bent, and FIG. 3 is a diagram showing the radius of curvature that occurs when the liquid crystal display device 1 is bent. FIG. 4 is a perspective view of a liquid crystal display device 10 according to an embodiment of the present invention, and FIG.
The drawings are a vertical sectional view of FIG. 4, FIG. 6 is an action diagram of tensile force and contractile force generated when the liquid crystal display device 10 according to the present invention is bent, and FIG. 7 is an enlarged action diagram of FIG. 6. 1.10...Liquid crystal display device, 2,3,11.12...
・Substrate, 14...Liquid crystal, 15...Mizo Agent Patent attorney Kei Nishi Part 1 Figure 2 Figure 3 Figure 4 Figure 6

Claims (1)

[Claims] A plurality of grooves perpendicular to the bending direction are formed on at least one of a pair of transparent substrates made of an organic material facing each other with a liquid crystal interposed therebetween on the surface opposite to the surface facing the liquid crystal. LCD display device.