JP2002244124A - Liquid crystal display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display without causing warpages and distortion under high temperature and high humidity environment, even in a structure having a polarizing plate attached to only one substrate out of a first substrate and a second substrate. SOLUTION: The array substrate 22 and the counter substrate 23 are placed opposite to each other via a gap and their peripheries are stuck together with an annular sealant 30. A liquid crystal layer 31 is formed, by injecting a liquid crystal between the array substrate 22 and the counter substrate 23 and sealing it. The polarizing plate 32 is stuck to the outer surface of the array substrate 22, and a film 39 is stuck to the outer surface of the counter substrate 23. Even if the polarizing plate 32 shrinks due to temperature and humidity changes, the film 39 shrinks similarly, thus the warpages and distortions are hardly caused to prevent the display quality from lowering.

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 in which a polarizing plate is provided on one of a first substrate and a second substrate.

[0002]

2. Description of the Related Art In general, a liquid crystal display device is widely used for a personal computer for a portable information terminal, and an active matrix type liquid crystal display device is particularly known. As an active matrix type liquid crystal display device, for example, a configuration described in Japanese Patent Application Laid-Open No. 9-199728 is known. In the liquid crystal display device described in Japanese Patent Application Laid-Open No. 9-199728, a plurality of signal electrodes and scanning electrodes, which are electrode films, are arranged in a grid on an insulating substrate having a light-transmitting property. A switching element is formed at each intersection of the electrodes, and a pixel electrode is connected to the switching element to form an array substrate. Similarly, a red, blue, and green colored layer and an electrode film are formed on an insulating substrate having a light-transmitting property. Are provided to constitute a counter electrode. A liquid crystal display device is described in which an array substrate and a counter substrate are opposed to each other with the electrode films facing each other, and a liquid crystal is sandwiched between the array substrate and the counter substrate.

[0003] An alignment film such as polyimide is applied to each surface of the array substrate and the counter substrate on which the electrode film is formed. Is applied. Then, the surfaces of the array substrate and the opposing substrate on which the electrode films are formed are arranged so as to face each other, the periphery of the array substrate and the opposing substrate are bonded with an annular sealant, and a part of the sealant is cut out. Liquid crystal is injected between the array substrate and the opposing substrate from the injection port thus formed and sealed. Further, a liquid crystal display device is completed by attaching a polarizing plate to the outer surfaces of the array substrate and the counter substrate.

[0004] In recent years, portable information terminals have become extremely popular, and products in which a touch panel is added to the surface of a personal computer have been widely used. Further, since low power consumption is required, a reflective structure which does not require a light source such as a backlight may be used as a liquid crystal display device in some cases.

[0005] Here, an antireflection film or a polarizing plate is attached to the surface of the touch panel in order to prevent image quality deterioration due to reflected light or diffused light. For this reason, the light transmittance of the touch panel is very low, about 10% to 20%, which is one of the factors that impair the characteristics of the product. In order to improve the light transmittance, there is a demand for a product that does not have a polarizing plate attached to the counter substrate side to which a touch panel is added.
In a reflection type liquid crystal display device, a polarizing plate is attached to a counter substrate side that receives reflected light.

As described above, many products with a touch panel and a reflection type liquid crystal display device have a polarizing plate attached only to one of an array substrate and a counter substrate.

As shown in FIG. 5, in the liquid crystal display device 11, an opposing substrate 13 is opposed to an array substrate 12, and an annular sealant is provided between the array substrate 12 and the opposing substrate 13.
Bonded with 14, sealant for array substrate 12 and counter substrate 13
The liquid crystal layer 15 is sandwiched between the portions surrounded by 14. And
For example, the polarizing plate 16 is attached only to the outer surface of the array substrate 12.

However, the polarizing plate 16 tends to shrink due to changes in temperature and humidity, and if an environmental test is performed at a high temperature or high humidity, the entire liquid crystal display device 11 will be warped or distorted as shown in the figure.

[0009]

As described above, the polarizing plate is provided only on one of the array substrate 12 and the counter substrate 13 constituting the liquid crystal display device 11, for example.
When attached, under the high-temperature or high-humidity environment test, the attached polarizing plate 16 shrinks due to temperature and humidity, so that the entire liquid crystal display device 11 is warped or distorted, thereby deteriorating the display quality. There is a problem that there is a possibility.

[0010] The present invention has been made in view of the above-mentioned problems, and even if a structure in which a polarizing plate is attached to only one of the first substrate and the second substrate is used, the warpage may occur in a high-temperature and high-humidity environment. It is an object of the present invention to provide a liquid crystal display device free from distortion and distortion.

[0011]

The present invention comprises a first substrate,
A second substrate provided facing the first substrate, a liquid crystal layer disposed between the first substrate and the second substrate, and an outer surface of one of the first substrate and the second substrate. And a film disposed on the other outer surface of one of the first substrate and the second substrate, wherein the outer surface of one of the first substrate and the second substrate is provided. Even if the polarizing plate disposed on the substrate shrinks due to temperature or humidity, since the film is attached to the outer surface of one of the first substrate and the second substrate, warpage or distortion may not occur entirely. To prevent the display quality from deteriorating.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings.

First, an active matrix transmission type liquid crystal display device will be described with reference to FIG.

As shown in FIG. 1, the liquid crystal display device 21 has an array substrate 22 as a first substrate and a counter substrate 23 as a second substrate facing the array substrate 22.

The array substrate 22 is formed on an insulating substrate 24 having a light-transmitting property by, for example, ITO (Indium Tin Oxide).
A plurality of signal electrodes and scanning electrodes formed of an electrode film of a transparent conductive film are arranged in a grid pattern, and a switching element is formed at each intersection of the signal electrode and the scanning electrode, and the switching element forms a pixel. An electrode 25 of an electrode film such as an electrode is formed.

On the other hand, a counter substrate 23 has a translucent insulating substrate 26 on which a red, blue and green colored layer 27 and a counter electrode 28 such as ITO are formed.

Then, an alignment film 29 of polyimide or the like is applied to the surface of each of the array substrate 22 and the counter substrate 23 on which the electrodes are formed, and a so-called rubbing alignment process for aligning liquid crystals in a specific direction is performed on the alignment film 29 Apply after heat curing. In addition, this rubbing is a cloth such as cotton or rayon,
This is an operation of rubbing the surface of the alignment film 29 at an angle of, for example, 45 degrees.

Thereafter, the array substrate 22 and the opposing substrate 23 are arranged to face each other with a gap in a state where the electrodes 25 of the array substrate 22 and the opposing electrodes 28 of the opposing substrate 23 are opposed to each other. Then, the periphery of the counter substrate 23 is bonded with an annular sealant 30. Also, this sealant
An injection port (not shown) is formed by cutting off a part of the ring shape in 30, and liquid crystal is injected and sealed between the array substrate 22 and the counter substrate 23 from this injection port to form a liquid crystal layer 31.

Further, since the liquid crystal display device 21 is of a transmissive type, if a light source for a backlight (not shown) is installed on the outer surface of the array substrate 22, for example, it is not shown on the outer surface of the counter substrate 23. A touch panel or the like is often added. Since the transmittance of the touch panel is low, no polarizing plate is provided on the outer surface of the counter substrate 23, and the polarizing plate 32 is attached only to the outer surface of the array substrate 22.

Further, as shown in FIG. 2, the transmission type polarizing plate 32 sandwiches a polarizer 35 formed of polyvinyl alcohol of an optical film with a triacetyl cellulose layer (TAC) 36 provided above and below. What these polarizers
An adhesive 37 is used for attaching the 35 and the triacetyl cellulose layer 36 and attaching them to other members (not shown). The surface of the polarizing plate 32 is subjected to a surface treatment such as an anti-glare treatment.

Further, as shown in FIG.
A transparent film 39 is attached to the outer surface of the counter electrode 28 to which the polarizing plate 32 is not attached. This film
As 39, for example, a polyethylene terephthalate layer (PET layer) is used.

With this configuration, the polarizing plate 32 is heated at a high temperature,
Even when shrinking under a high-humidity environment test, the film 39 attached to the outer surface of the counter substrate 23 to which the polarizing plate 32 is not attached minimizes the warpage that tends to occur in the liquid crystal display device 21. Can be suppressed. Therefore, the liquid crystal display device is resistant to high-temperature and high-humidity environments and has stable display quality.

According to the experiment, the polarizer 35 is about 1 m in the direction of the arrow shown in the figure under the high temperature and high humidity environment test.
shrink by m to 2 mm. For this reason, the liquid crystal display device 21 in which the polarizing plate 32 is attached to the outer surface, as shown in FIG.
Although warpage of about 1 mm has occurred in the whole, which has caused the deterioration of image quality, the whole warp almost disappears by attaching the film 39.

Next, an active matrix reflective liquid crystal display device will be described with reference to FIG.

As shown in FIG. 3, the basic structure of the liquid crystal display device 41 itself is substantially the same as that of the transmission type shown in FIG. 2, and the liquid crystal display device 41 faces the array substrate 42 as the first substrate and the opposing substrate as the second substrate. 43 are arranged. Further, the array substrate 42 is provided with electrodes 45 of electrode films such as signal electrodes, scanning electrodes and pixel electrodes on an insulating substrate 44 having a light transmitting property, and the counter substrate 43 is also provided with red, blue and A green colored layer 47, a transparent counter electrode 48, and the like are formed. Further, after forming an alignment film 49 on the array substrate 42 and the counter substrate 43, an annular sealing agent 50 is formed, and a liquid crystal layer 51 is formed between the array substrate 42 and the counter substrate 43 surrounded by the sealing agent 50. are doing.

The difference from the transmission type is that the array substrate 42
The pixel electrode of the electrode 45 is formed of aluminum or the like. When the pixel electrode of the electrode 45 is made of aluminum as described above, light incident from the counter substrate 43 side is reflected by the pixel electrode of the reflection electrode 45 toward the counter substrate 43 side. Therefore, the polarizing plate 52 is attached to the outer surface of the counter substrate 43.

As shown in FIG. 4, the reflective polarizing plate 52 has a polarizer 53 formed of polyvinyl alcohol of an optical film sandwiched between triacetyl cellulose layers (TAC) 54 provided on the upper and lower sides. What these polarizers
An adhesive 55 is used for attaching the 53 and the triacetyl cellulose layer 54 and attaching them to other members (not shown). The surface of the polarizing plate 52 is subjected to a surface treatment 56 such as an anti-glare treatment. Further, a retardation plate 57 such as polycarbonate (PC) is an adhesive.
Installed at 55.

Since the polarizing plate 52 is attached to the outer surface of the counter substrate 43, a film 58 of, for example, a polyethylene terephthalate layer (PET layer) is attached to the outer surface of the array substrate 42.

With this configuration, even when the polarizing plate 52 shrinks under a high-temperature and high-humidity environment test, the polarizing plate 52 is adhered similarly to the liquid crystal display device 21 shown in FIGS. The film 58 stuck to the outer surface of the array substrate 42 that is not present can minimize the warpage that is likely to occur in the liquid crystal display device 41. Therefore, the liquid crystal display device is resistant to high-temperature and high-humidity environments and has stable display quality.

The places where the films 39 and 58 are attached are as follows:
Of the array substrates 22 and 42 or the opposing substrates 23 and 43 constituting the liquid crystal display devices 21 and 41, the other outer surface to which the polarizing plates 32 and 52 are not attached may be used. Similar effects can be obtained.

The liquid crystal display devices 21 and 41 are not limited to the active matrix type, but may be of another type.

[0032]

According to the present invention, even if the polarizing plate disposed on one of the outer surfaces of the first substrate and the second substrate shrinks due to temperature and humidity, the first substrate and the second substrate can be removed. Since a film is stuck on one of the other outer surfaces, no warpage or distortion occurs on the whole, and a decrease in display quality can be prevented.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a transmission type liquid crystal display device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view schematically showing a polarizing plate of the liquid crystal display device.

FIG. 3 is a sectional view showing a reflective liquid crystal display device according to another embodiment of the present invention;

FIG. 4 is a schematic sectional view of a polarizing plate of the liquid crystal display device.

FIG. 5 is an explanatory view showing a conventional liquid crystal display device.

[Explanation of symbols]

 21, 41 Liquid crystal display device 22, 42 Array substrate 23, 43 first substrate Counter substrate 25, 45 second electrode Electrodes 31, 51 Liquid crystal layer 32, 52 Polarizing plate 39, 58 Film

Claims (4)

[Claims] A first substrate; a second substrate provided to face the first substrate; a liquid crystal layer provided between the first substrate and the second substrate; A liquid crystal display comprising: a polarizing plate disposed on one of the outer surfaces of two substrates; and a film disposed on the other outer surface of the first substrate and the second substrate. apparatus. 2. The liquid crystal display device according to claim 1, further comprising at least an electrode film made of a transparent material formed on the first substrate. 3. The liquid crystal display device according to claim 1, further comprising an electrode film made of a reflective material formed on the first substrate, wherein the polarizing plate is provided on an outer surface of the second substrate. . 4. The liquid crystal display device according to claim 1, further comprising a touch panel provided on an outer surface of one of the first substrate and the second substrate.