JPH0734415Y2 - Liquid crystal display - Google Patents

Description

[Detailed description of the device] [Industrial applications]

 The present invention relates to a liquid crystal display device.

[Prior art and problems to be solved]

For example, in the case of a TN (twisted nematic) type liquid crystal display device, its general structure is as shown in FIG. As shown in the figure, this liquid crystal display device is adhered to a pair of glass substrates 2 and 2'which are opposed to each other with a minute gap therebetween and in which the liquid crystal 1 is sandwiched, and the surfaces of the glass substrates 2 and 2 '. It is provided with polarizing plates 3 and 3 '. Transparent conductive films 4 and 4'are formed on predetermined portions inside the glass substrates 2 and 2 ', respectively, and the liquid crystal 1 is formed on the transparent conductive films 4 and 4'.
Alignment films 5 and 5 ′ for directing the molecular arrangement of are provided in a laminated form. The alignment films 5 and 5'are formed so that the alignment direction with respect to the liquid crystal 1 is deviated, for example, by 90 ° between the substrates 2 and 2 on both sides, whereby the liquid crystal 1 between the substrates 2 and 2 is twisted by, for example, 90 °. It is made possible to obtain a so-called twisted nematic arrangement. In the case of general so-called positive display type, glass substrate
Polarizing directions of the polarizing plates 3 and 3'disposed on both sides of the polarizing plates 2 and 2'are orthogonal to each other, and the respective polarizing directions are the glass substrate 2
It is provided so as to coincide with the alignment direction of the alignment films which face each other with the film sandwiched therebetween. When no voltage is applied between both electrodes (transparent conductive films) 4 and 4 ′ of the glass substrates 2 and 2 ′, the linear deflection passing through one polarizing plate 3 is rotated by 90 ° by the twisted nematic liquid crystal 1. Therefore, it can pass through the other polarizing plate 3 '. In this case, no contrast difference occurs and no lighting is performed. On the other hand, when a voltage is applied, the liquid crystal 1 located between the transparent conductive films 4 and 4'on the glass substrates 2 and 2'has its molecules parallel to the direction of the electric field generated between the transparent conductive films 4 and 4 '. . At this time, of the light passing through one of the polarizing plates 3, the linearly polarized light passing between the transparent conductive films 4 and 4 is not subjected to the optical rotation effect by the liquid crystal 1 unlike when no voltage is applied. You cannot pass 3. Therefore, that portion is lit in black. In this case, by forming a pattern with a transparent conductive film, it is possible to perform lighting display according to the pattern. By the way, in such a liquid crystal display device, the polarizing plate 3,
3 ′ plays an important role in lighting control through light transmission / blocking control that allows only linearly polarized light in a specific direction to pass, and the quality of the polarization performance greatly affects the quality of the device. To do. Generally, as shown in FIG. 4, the polarizing plate 3 includes a polarizer 3a formed by adsorbing iodine on a chain polymer film such as polyvinyl alcohol, and an acrylic film formed on the front and back surfaces of the polarizer 3a. It has a three-layer structure of protective coatings 3b and 3b such as or triacetate. When the device is attached, it is usually attached to the surface of the glass substrate 2 after being cut into a predetermined shape and size. However, conventionally, the cut polarizing plate 3 is directly attached to the glass substrate 2 without any terminal treatment, and the polarizer 3a is exposed at the cut end face. There is a problem in that water molecules in the air enter the inside, which deteriorates the quality of the polarizing plate 3. Polyvinyl alcohol forming the polarizer 3a has a water-soluble property and is improved in water resistance, so that when the polarizer 3a is exposed, it is easy to absorb moisture in the air or the like from the exposed portion, and Due to
This causes a change in characteristics, impairs the polarization performance, and causes darkening in the display section. Therefore, conventionally, the quality of the device could not be guaranteed for a long time. The present invention has been devised under the circumstances as described above, and has a simple structure and can maintain the polarization performance of the polarizing plate constant for a long period of time and perform good lighting display. By providing a liquid crystal display device configured as
It is an object to solve the above conventional problems.

[Means for Solving the Problems]

In order to solve the above problems, the present invention takes the following technical means. That is, the invention of the present application encloses a liquid crystal between a pair of transparent substrates which are opposed to each other with a minute gap, and a polarizer and a protective coating formed on the front and back surfaces of the polarizer on the surface of the transparent substrate. A liquid crystal display device having a polarizing plate attached thereto, the protective coating being formed slightly larger than the polarizer to form a groove-shaped gap between the peripheral portions of both protective coatings. A sealing treatment is applied to the peripheral edge of the polarizing plate by filling the gap with a sealing material.

[Function and effect of device]

As described above, the polarizing plate is formed in a three-layer structure including the polarizer and the protective coatings formed on the front and back surfaces, and there is a problem in the water resistance of the above-mentioned polarizer forming the intermediate layer. In the present invention, the peripheral portion of the polarizer exposed to the outside is sealed by performing the sealing process.
Therefore, it is possible to prevent water from entering the polarizer. Moreover, the seal structure according to the present invention is configured by filling the groove-shaped gap formed by forming both protective films one size larger than the above-mentioned polarizer with the seal material. Therefore, the sealing material itself is protected by the protective coating. Therefore, the sealing ability is extremely higher than that of the seal structure in which the sealing material is simply attached to the edge portion. Therefore, it is possible to maintain the polarization performance of the polarizing plate constant for a long period of time, to perform good lighting display, and improve the reliability of the quality of the device. Moreover, the sealing material does not protrude from the edge of the protective film. Therefore, even if the above-mentioned sealing process is performed,
It is possible to form a polarizing plate having high dimensional accuracy without changing the dimensions of the polarizing plate. In addition, since the sealing material is held in the gap, the sealing material in the curing process hardly deforms or flows. Therefore, the work efficiency can be significantly improved.

[Explanation of Examples]

Hereinafter, embodiments of the present invention will be described with reference to the drawings. This example is an example in which the present invention is applied to a transmissive liquid crystal display device as shown in FIGS. 2 and 3. As described above, the liquid crystal display device includes a pair of glass substrates 2 and 2'which are opposed to each other with a minute gap therebetween, and polarizing plates 3 and 3'which are attached to the surfaces of the glass substrates 2 and 2 '. Equipped with
It has a structure in which the liquid crystal 1 is enclosed between the glass substrates 2 and 2 '. Transparent conductive films 4 and 4'are formed on predetermined portions inside each of the glass substrates 2 and 2 ', and by applying a voltage between the electrodes, arbitrary display can be performed. . The illustrated example is a so-called positive display type, and the polarizing plates 3 and 3'on both sides are provided so that their polarization directions are orthogonal to each other. Therefore, when a voltage is applied, the linearly polarized light passing through one of the polarizing plates 3 is not rotated by the liquid crystal 1 and cannot pass through the other polarizing plate 3 ', so that part is illuminated in black. In FIG. 3, reference numeral 6 indicates a sealing resin which also serves as a spacer between the glass substrates 2 and 2 '. Also, the substrate 2,
The 2'can also be made of transparent plastic, for example. In the present invention, as shown in FIGS. 1 and 2, a seal 7 is provided on the peripheral edge of the polarizing plates 3, 3 '. As shown in the figure, the polarizing plate 3 (3 ') has a three-layer structure of a polarizer 3a and protective coatings 3b, 3b formed on the front and back surfaces thereof, and usually has a rectangular shape corresponding to the shape of the glass substrate. It is attached to a glass substrate by cutting. In this example, the sealing process is performed over the entire circumference of the polarizing plates 3 and 3 '. In this embodiment, as clearly shown in FIG. 1, the upper and lower protective coatings 3b, 3b are formed to be slightly larger than the polarizer 3a, thereby forming a groove-shaped gap in the peripheral portion of the polarizing plate. By filling the gap with a sealing material, the edge of the polarizer 3a is covered and the sealing process is performed. A resin such as an ultraviolet curable resin or an adhesive such as an epoxy resin adhesive can be used as the sealing material, and it is desirable to select a material having high water resistance when selecting the material. In addition, the sealing process is performed on the glass substrate 2
The sealing process may be performed before or after the mounting, but if the sealing resin 6 is formed at the same time, the sealing process can be performed at low cost without increasing the number of steps. In this way, in the liquid crystal display device of the present invention in which the peripheral edges of the polarizing plates 3 and 3'are sealed, the polarizing plates 3 and 3'are different from the conventional ones.
The polarizer 3a is not exposed at the cut end face of (1) and water can be prevented from entering the polarizer 3a. Therefore, for a long period of time, the polarization characteristics of the polarizing plates 3 and 3'are kept constant,
The quality of the equipment can be guaranteed. Moreover, the sealing material does not protrude from the edges of the protective coatings 3b, 3b. Therefore, the size of the polarizing plate does not change even if the sealing process is performed, and a polarizing plate with high dimensional accuracy can be formed. In addition, since the sealing material is held in the gap, the sealing material in the curing process hardly deforms or flows. Therefore, the work efficiency can be significantly improved. By the way, the scope of the present invention is not limited to the above-mentioned embodiments. For example, when applying the present invention, the type of the device is not particularly limited, and the present invention is a reflection type device that uses the reflected light to perform lighting display, or a pair of polarizing plates whose polarization directions are parallel to each other. It can be applied to a so-called negative display type device arranged so that there is no problem.

[Brief description of drawings]

FIG. 1 is a sectional view of a polarizing plate according to an embodiment of the present invention, and FIG.
FIG. 1 is a diagram schematically showing the external appearance of the liquid crystal display device according to the embodiment, FIG. 3 is a sectional view schematically showing the liquid crystal display device, and FIG. 4 is a diagram for explaining the conventional problems. is there. 1 ... Liquid crystal, 2,2 '... Transparent substrate (glass substrate), 3,3'
…… Polarizing plate, 7 …… Seal.

Claims (1)

[Scope of utility model registration request] 1. A liquid crystal is enclosed between a pair of transparent substrates which are opposed to each other with a minute gap therebetween, and a polarizer and protective films formed on the front and back surfaces of the polarizer are provided on the surface of the transparent substrate. A liquid crystal display device comprising a polarizing plate attached to the polarizing plate, wherein the protective coating is formed to be slightly larger than the polarizer to form a groove-shaped gap between the peripheral portions of both protective coatings. A liquid crystal display device, wherein a peripheral edge of the polarizing plate is sealed by filling a sealing material into the liquid crystal display device.