JP2002014226A - Polarizing film and display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polarizing film with improve display quality by eliminating unevenness. SOLUTION: Only one protective layer 43 is used as a protective layer by omitting a triacetyl cellulose protective layer. Internal stress and photoelasticity resulting from combination caused by laminated body formation are reduced according to one layer. Optical distortion is reduced, difference of transmittance between an adhered part and not adhered part via a polarizer 42 is reduced and picture quality is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polarizing film and a display device which do not degrade the screen quality.

[0002]

2. Description of the Related Art Conventionally, for example, a structure shown in FIG. 4 is known as a polarizing film for a liquid crystal display element of this kind. The polarizing film 1 shown in FIG. 4 has a support 2 which is an effective portion of the polarizing film. The support 2 has a polyvinyl alcohol (PVA) polarizer 3 positioned on both sides of the polarizer 3 and has a It has two protective layers 4 and 5 of triacetyl cellulose (TAC) for protecting the child 3.

Further, an adhesive layer 6 for bonding to a liquid crystal display element (not shown) is formed on the support 2, and a peelable release film 7 for protecting the adhesive layer 6 is attached to the adhesive layer 6. In addition, a surface protection film 8 for preventing dirt and scratches on the surface of the support 2 is provided on the surface side of the support 2 to constitute a laminated film.

As another conventional polarizing film, for example, a structure shown in FIG. 5 is known. This figure 5
The polarizing film 1 shown in FIG.
An optical film 12 such as a wide viewing angle film or a brightness enhancement film is adhered to the adhesive layer 6, and the optical film 12 is obtained by providing an adhesive layer 14 on a substrate 13 of triacetyl cellulose. It constitutes a three-layer laminated film.

[0005] In any of the polarizing films 1 shown in FIGS. 4 and 5, in the heating step in the production of the liquid crystal display element, the surface protective film 8 which has been peeled off once during the production is used in order to prevent breakage during operation. I'm wearing a pledge. In some cases, an adhesive film corresponding to the surface protection film 8 may be attached before heat treatment.

[0006]

However, when the surface protective film 8 or the adhesive film is adhered, air bubbles enter between the support 2 and the support 2 and the surface protective film 8 because it is a manual operation. Alternatively, a contact portion and a non-contact portion exist between the pressure-sensitive adhesive film and the pressure-sensitive adhesive film. As described above, by performing a process such as heating for a long time in a state where the contact portion and the non-contact portion exist between the support 2 and the surface protection film 8 or the adhesive film, the contact portion and the non-contact portion can be separated. Different shear stress and shear stress are generated in the portions of the protective layers 4 and 5, and after returning to normal temperature and peeling off the surface protective film 8 or the adhesive film, the internal stress becomes photoelastic in the protective layers 4 and 5 and adheres. Different optical distortion occurs between the portion and the non-contact portion. When the different photoelastic phenomena are passed through the polarizer 3, the difference in the transmittance is visually recognized as unevenness.

On the other hand, when the heat treatment is performed without attaching the surface protection film 8 or the adhesive film, the liquid crystal display element may be damaged during the heat treatment work, although unevenness due to photoelasticity does not occur.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a polarizing film and a display device having improved display quality without unevenness.

[0009]

According to the present invention, there is provided a polarizing sheet-like polarizer, a protective layer adhered to one side of the polarizer, and a surface of the polarizer on the side of the protective layer. With an adhesive layer formed on the opposite surface, the number of protective layers is reduced by one, so that internal stress and photoelasticity are reduced by one layer, optical distortion is reduced, and the adhesive part and non-adhesive The difference in the transmittance with respect to the unit is reduced to achieve a good screen quality.

Further, the present invention provides a polarizing sheet-like polarizer, a protective layer adhered to one surface of the polarizer, and a surface of the polarizer opposite to the protective layer. And an optical film formed on a surface of the adhesive layer opposite to the surface on the polarizer side.
By reducing the number of layers, the internal stress and the photoelasticity are reduced by one layer to reduce the optical distortion, and the difference in the transmittance between the adhesive portion and the non-adhesive portion is reduced, resulting in a good screen quality.

The optical film comprises a substrate formed on a surface of the adhesive layer opposite to the polarizer, and an adhesive layer formed on a surface of the substrate opposite to the surface of the adhesive layer. And

Further, the protective layer has a surface protective film formed on the surface of the protective layer opposite to the polarizer.

Still further, the polarizer is a polyvinyl alcohol.

The protective layer is made of triacetyl cellulose.

[0015] Further, a release film attached to the adhesive layer is provided.

Also, an array substrate having a plurality of pixel electrodes, a counter substrate disposed to face the array substrate,
A light modulating layer held between the array substrate and the counter substrate, a polarizing film adhered to a surface of the array substrate and the counter substrate opposite to the light modulating layer, and a backlight. .

Further, the light modulation layer is a liquid crystal layer.

[0018]

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

As shown in FIG. 2, the liquid crystal display device 21 has a liquid crystal display element 22. The liquid crystal display element 22 is
An array substrate 23 having a plurality of pixel electrodes is provided, and a counter substrate 24 is provided so as to face the array substrate 23.
A liquid crystal layer 25 serving as a light modulation layer is formed between 23 and the counter substrate 24. Further, the array substrate 23 and the counter substrate 24
, A polarizing film 26 is stuck.

On the back side of the liquid crystal display element 22, a backlight 31 is provided. This backlight 31
The lamp light source 33 is provided on one end side of the light guide plate 32, the reflection sheet 34 is provided on the back side of the light guide plate 32, and the high brightness film 35 is provided on the front side where the liquid crystal display element 22 is located. Has been established.

As shown in FIG. 1, the polarizing film 26 has a support 41 which is an effective portion of the polarizing film, and the support 41 is a polarizer made of polyvinyl alcohol (PVA).
The polarizer 42 has only one protective layer 43 of triacetyl cellulose (TAC) which is located only on one surface side of the polarizer 42 and protects the polarizer 42.

An adhesive layer 44 for bonding to the liquid crystal display element 22 is formed on the support 41, and a peelable release film 45 for protecting the adhesive layer 44 is attached to the adhesive layer 44. On the surface side of the support 41, a surface protection film 46 for preventing dirt, scratches and the like on the surface of the support 41 is provided,
It constitutes a laminated film.

As another polarizing film 26, for example, a configuration shown in FIG. 3 is known. The polarizing film 26 shown in FIG. 3 is obtained by attaching an optical film 47 such as a wide viewing angle film or a brightness enhancement film to the adhesive layer 44 in the embodiment shown in FIG.
Is a triacetyl cellulose substrate 48 provided with an adhesive layer 49, and triacetyl cellulose constitutes a three-layer laminated film.

Thus, as shown in FIG. 1, the conventional protective layer 5 of triacetyl cellulose was omitted, and
By using one layer 43 and two layers of the protective layer 43 and the base material 48 as shown in FIG. 3, it is possible to reduce the internal stress and photoelasticity caused by the lamination by one layer, As a result, optical distortion can be reduced, and the difference in transmittance between the adhesive portion and the non-adhesive portion via the polarizer 42 can be reduced. Therefore, the screen quality is improved.

According to experiments, the polarizing film 26 was heated at a high temperature of 50 ° C.
Immediately after storing for 7 hours in an environment of 0 ° C., the transmittance of the adhered portion and the non-adhered portion is measured at room temperature, and a sample to be measured is placed on a glass substrate so that the absorption axis of the polarizer 42 is orthogonal (crossed Nicol). And stick it across.

As shown in Table 1, the polarizing film 26 shown in FIG. 1 has a relative change of 9.14 in transmittance between the adhesive portion and the non-adhesive portion in comparison with the polarizing film 1 shown in FIG.
3 and the change in transmittance of the adhesive film and the non-adhesive portion of the polarizing film 26 shown in FIG. 3 was reduced by 14.8% as compared with the polarizing film 1 shown in FIG.

Therefore, the change in transmittance between the contact portion and the non-contact portion can be reduced by about 9 to 15% as compared with the related art.

[0028]

[Table 1] Each of the protective layers 5 of triacetyl cellulose was
By omitting the layers, the thickness can be reduced, and the array substrate 23
In addition, it is possible to reduce the thickness of the opposite substrate 24 by two layers on the front and back sides.

[0029]

According to the present invention, by reducing the number of protective layers by one, the internal stress and photoelasticity are reduced by one layer to reduce optical distortion, and the transmittance of the adhesive portion and the non-adhesive portion is reduced. Good screen quality can be achieved by reducing the difference.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the polarizing film of the present invention.

FIG. 2 is a schematic diagram showing a liquid crystal display device of the above.

FIG. 3 is a cross-sectional view showing a polarizing film according to another embodiment of the present invention.

FIG. 4 is a sectional view showing a conventional polarizing film.

FIG. 5 is a cross-sectional view showing another conventional polarizing film of the above.

[Explanation of symbols]

 21 Liquid crystal display device 23 Array substrate 24 Opposite substrate 25 Liquid crystal layer as light modulating layer 26 Polarizing film 31 Backlight 42 Polarizer 43 Protective layer 44 Adhesive layer 45 Release film 46 Surface protective film

Claims (9)

[Claims] 1. A polarizing sheet-like polarizer, a protective layer adhered to one surface of the polarizer, and a surface of the polarizer opposite to the surface of the protective layer. A polarizing film comprising an adhesive layer. 2. A sheet-like polarizer for polarizing light, a protective layer adhered to one surface of the polarizer, and an adhesive layer formed on the surface of the polarizer opposite to the protective layer. A polarizing film, comprising: an optical film formed on a surface of the adhesive layer opposite to the surface on the polarizer side. 3. An optical film comprising: a substrate formed on a surface of the adhesive layer opposite to the polarizer; and an adhesive layer formed on a surface of the substrate opposite to the surface of the adhesive layer. The polarizing film according to claim 2, comprising: 4. The polarizing film according to claim 1, further comprising a surface protective film formed on a surface of the protective layer opposite to the polarizer. 5. The polarizing film according to claim 1, wherein the polarizer is polyvinyl alcohol. 6. The polarizing film according to claim 1, wherein the protective layer is made of triacetyl cellulose. 7. The polarizing film according to claim 1, further comprising a release film attached to the adhesive layer. 8. An array substrate having a plurality of pixel electrodes, a counter substrate disposed to face the array substrate, a light modulation layer held between the array substrate and the counter substrate, and the array substrate 7. A display device comprising: the polarizing film according to claim 1 stuck on a surface of the opposite substrate opposite to the light modulation layer; and a backlight. 9. The display device according to claim 8, wherein the light modulation layer is a liquid crystal layer.