JPH08110521A - Liquid crystal display panel - Google Patents

Abstract

PURPOSE: To obviate the deterioration in polarization performance and to make this panel well visible even in severe environment, such as in vehicles, by sticking light transmissive resin plates which are low in shrinkage degree and high in modulus of elasticity than polarizing plates on both of a liquid crystal cell to the outer side of these polarizing plates. CONSTITUTION: The liquid crystal cell S is constituted by holding liquid crystals 6 between a substrate 1 arranged with active elements 2 at respective pixels and a counter substrate 3. The polarizing plates 5, 4 which have the axes of polarization intersecting orthogonally with each other are stuck on the glass surfaces on the outer side of the substrate 1 and counter substrate 3 of the liquid crystal cell S and further, the light transmissive resins plates 11 which are low in shrinkage degree and high in modulus of elasticity than the polarizing plates 5, 4 are stuck to the outer surface of both polarizing plates 5, 4. The shrinkage of the polarizing plates 5, 4 by drying, etc., of the liquid crystal display panel constituted in such a manner is prevented by the resin plates 11 and, therefore, the stresses on the glass surfaces of the liquid crystal cell S and the protective plate 9 on the glass surface side are decreased in the case of using under a severe environment, such as high temp. and high humidity, by which the induction of the double refraction is prevented and the deterioration in the polarization performance is lessened.

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 panel for matrix display.

[0002]

2. Description of the Related Art FIG. 2 is a schematic cross-sectional view showing the structure of a conventional liquid crystal display panel, in which 1 is a substrate, 2 is an active element, 3 is a counter substrate, 4 and 5 are polarizing plates, 6 is a liquid crystal, and 7 is a liquid crystal. An adhesive, 8 is a polarizer, 9 is a protective plate, and 10 is a backlight.

The conventional liquid crystal display panel shown in FIG. 2 is a transmissive panel, and is a liquid crystal cell in which a liquid crystal 6 is sandwiched between a substrate 1 on which an active element 2 is arranged in each pixel and a counter substrate 3. Polarizing plates 4 and 5 are arranged on both sides of S such that their polarization axes are orthogonal to each other, and a backlight 10 is arranged outside the lower polarizing plate 5.

The polarizing plates 4 and 5 are composed of a polarizer 8 and a protective plate 9. Polarizing light incident on the polarizing plates 4 and 5 is a polarizer 8 made of stretched polyvinyl alcohol. Is. However, the polarizer 8 is weak in mechanical strength and contracts easily due to heat or moisture to deteriorate the polarization performance. Therefore, the polarizer 8 is protected by being sandwiched between protective plates 9 made of triacetylserose. . Further, the polarizing plates 4 and 5 are attached to the liquid crystal cell S by the adhesive 7 applied to one surface of the protective plate 9.

An alignment film (not shown) is provided inside the two electrode substrates, that is, the substrate 1 and the counter substrate 3. By applying a voltage to the substrate 1 and the counter substrate 3, the liquid crystal 6 is formed. Is formed so that the alignment of liquid crystal molecules is continuously twisted between the upper and lower electrodes.

In such a structure, the backlight 10
The light from is polarized by the lower polarization plate 5, and the direction of polarization is rotated by the twisted arrangement of the liquid crystal 6 when no voltage is applied, so that the light can pass through the upper polarization plate 4. However, when the liquid crystal molecules are aligned in the direction of the electric field by applying a voltage, the liquid crystal 6 loses the directivity for rotating the polarization direction, and thus cannot pass through the upper polarizing plate 4. This allows the electric field application section to be displayed as a dark pattern on a bright background.

[0007]

SUMMARY OF THE INVENTION Like the conventional configuration,
Polarizer 8 made of stretched polyvinyl alcohol
Both sides of the protective plate 9 made of triacetyl cellulose
The polarizing plates 4 and 5 which are configured by sandwiching and fixing with the adhesive 7 and attached to the glass of the liquid crystal cell S with the polarizer 8 and the protective plate 9 for drying in an environment such as high temperature. Although they try to shrink together, they are prevented from shrinking because they are attached to the glass of the liquid crystal cell S via the adhesive 7. Therefore, stress is applied to both the protective plate 9 and the glass of the liquid crystal cell S via the adhesive 7, so that a minute birefringence occurs.

Further, this stress acts from the periphery of the polarizing plates 4 and 5 to the central portion thereof, and the contraction amount becomes larger especially toward the periphery, so that the stress becomes large and a large birefringence occurs. This birefringence shows the polarization performance of the incident light in the transmissive liquid crystal display panel as shown in FIG.
There is a problem that the image quality such as contrast is deteriorated and the visibility is remarkably impaired due to deterioration in (shaded area).

Although there is already a liquid crystal display panel in which a resin plate having a high transmittance is attached to one of the polarizing plates, the other polarizing plate to which the resin plate is not attached has the same stress of shrinkage at high temperature. As a result, birefringence occurs and the performance of the polarizing plate is deteriorated. Therefore, the liquid crystal display panel has a problem that the image quality such as contrast is deteriorated and the visibility is impaired.

An object of the present invention is to provide a liquid crystal display panel which can prevent deterioration of polarization performance due to contraction of a polarizing plate and can obtain good visibility even in a harsh environment such as a vehicle.

[0011]

In order to achieve the above object, a liquid crystal display panel of the present invention is a liquid crystal cell in which a liquid crystal is sandwiched between two electrode substrates which are arranged to face each other, and this liquid crystal cell. In a liquid crystal display panel comprising a pair of polarizing plates arranged on both sides of the liquid crystal cell, a polarizing plate having optical transparency outside the both polarizing plates arranged on both sides of the liquid crystal cell and having a contraction amount from the polarizing plate. It is characterized in that resin plates having a small amount of elasticity and a high elastic modulus are stuck together.

[0012]

According to this structure, when the liquid crystal display panel is used at a high temperature for a long time, the polarizing plate tends to shrink due to drying, but a resin plate having a smaller shrinkage amount and a higher elastic modulus than the polarizing plate is used. Since they are attached to each other, shrinkage of the polarizing plate can be reduced. Therefore, stress on the protective plate and the glass of the liquid crystal cell via the adhesive is relieved, and the occurrence of birefringence is reduced. Furthermore, since the polarization performance of the transmissive liquid crystal display panel is not deteriorated, the image quality such as contrast is not deteriorated and the visibility is not impaired.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. The same members as those in the conventional example shown in FIG. 3 are designated by the same reference numerals, and detailed description thereof is omitted.

FIG. 1 is a schematic cross-sectional view showing the structure of a transmissive liquid crystal display panel according to this embodiment. A liquid crystal cell S is provided between a substrate 1 on which an active element 2 is arranged in each pixel and a counter substrate 3. It is configured by sandwiching the liquid crystal 6. Then, in the liquid crystal display panel of the present embodiment, the polarizing plate 5 is attached to the glass surface outside the substrate 1 of the liquid crystal cell S with the adhesive 7, and the polarizing axis is the polarizing plate 5 on the glass surface outside the counter substrate 3. A polarizing plate 4 is attached with a pressure sensitive adhesive 7 so as to be orthogonal to each other, and a resin having a smaller shrinkage amount, a higher elastic modulus, and a light transmitting property than the polarizing plates 4 and 5 on the outer surfaces of both polarizing plates 4 and 5. The plate 11 has a structure in which it is attached via an adhesive (not shown).

The liquid crystal display panel having the above structure is
When used in a severe environment such as high temperature, high temperature and high humidity, for example, when mounted in a vehicle, the polarizing plates 4, 5
Tends to shrink due to drying or the like, but since the resin plates 11 having a smaller shrinkage amount and a higher elastic modulus than the polarizing plates 4 and 5 are attached, the polarizing plates 4 and 5 can be prevented from shrinking.
The stress on the glass surface and the protective plate 9 on the glass surface side is reduced, and the induction of birefringence can be reduced. Therefore, the deterioration of the polarization performance of the transmissive liquid crystal display panel is reduced, the image quality such as contrast is not deteriorated, and the visibility is not impaired.

[0016]

According to the present invention configured as described above, a resin plate having a smaller amount of shrinkage and a higher elastic modulus than the polarizing plates is attached to the outside of the polarizing plates on both sides of the liquid crystal cell via an adhesive. With this configuration, even when used in a severe environment such as high temperature, high temperature and high humidity, the polarizing plate can be prevented from contracting due to the rigidity of the resin plate, so that birefringence does not occur. Therefore, it is possible to reduce the deterioration of the polarization performance of the transmissive liquid crystal panel during application, and it is possible to obtain good visibility.

[Brief description of drawings]

FIG. 1 is a side view showing a configuration of an embodiment of a liquid crystal display panel of the present invention.

FIG. 2 is a side view showing a configuration of a conventional liquid crystal display panel.

FIG. 3 is an explanatory diagram showing a state of deterioration of polarization performance due to contraction of a polarizing plate.

[Explanation of symbols]

1 ... Substrate, 2 ... Active element, 3 ... Counter substrate, 4, 5
... polarizer, 6 ... liquid crystal, 7 ... adhesive, 8 ... polarizer,
9 ... Protective plate, 10 ... Backlight, 11 ... Resin plate, S
… Liquid crystal cell.

Claims (1)

[Claims] 1. A liquid crystal display panel comprising a liquid crystal cell in which a liquid crystal is sandwiched between two electrode substrates which are arranged to face each other, and a pair of polarizing plates which are disposed on both sides of the liquid crystal cell. A liquid crystal having a light-transmitting resin plate, which has a light-transmitting property, a shrinkage amount smaller than that of the polarizing plate, and a high elastic modulus, is attached to the outside of both polarizing plates arranged on both sides of the liquid crystal cell. Display panel.