JP2001166141A - Optical film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical film capable of suppressing interlayer peeling from the corners of the film at the polarization-separating plate part and capable of enhancing yield. SOLUTION: The optical film has a protective film 3 and a polarization- separating plate 2 and the corners of the film have been curved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an optical film.

[0002]

2. Description of the Related Art An optical film provided with a linear polarizing plate absorbs linearly polarized light having a vibration plane parallel to the direction of its absorption axis, and forms a vibration plane parallel to a direction perpendicular to the absorption axis (transmission axis). It is an optical element having a function of transmitting linearly polarized light, and is widely used as one of optical elements constituting a liquid crystal display device, for example.

In a liquid crystal display device, two linear polarizers are used, and are disposed on the back side and the front side of a liquid crystal cell. On the back side of the linear polarizing plate provided on the back side, a reflector and a light source are provided.

It is well known that the brightness can be improved by disposing a polarization separating plate between a linear polarizing plate disposed on the back side and a reflecting plate or a light source. In such a liquid crystal display device, the brightness can be improved. For example, when the brightness is set to be the same as that without a polarization separation plate, the backlight can be darkened and power can be saved. Demand for films is increasing.

[0005] When a depolarized light, such as natural light, enters, a polarization splitter separates this light into two polarized lights, one of which is transmitted, and the other is transmitted. An optical component having the function of reflecting, for example, formed by alternately laminating a large number of two types of polymer films having different refractive indices, transmitting linearly polarized light in one direction, and having a vibration direction in a direction perpendicular to the direction. 2. Description of the Related Art A polarization separation plate having a property of reflecting linearly polarized light is known. As an example of such a polarization separating plate, there is one formed by co-extrusion of a naphthalenedicarboxylic acid polyester and another polymer.

[0006]

As described above, the polarized light separating plate is formed by alternately laminating a large number of two kinds of films. Is not good.

[0007] For this reason, in a line or the like for cutting the optical film into a predetermined shape, in a trimming step or other steps, it comes into contact with another object such as a pallet or the like, thereby causing a corner of the film to peel. When the protective film is peeled off to be used as a product after shipment as an optical film, peeling may occur between layers of each film in the polarization separator, and the polarization separator may peel off together with the protective film. Was.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an optical film capable of suppressing a problem of delamination at a polarization separating plate portion from a corner of a film and improving a yield. On the point.

[0009]

The constitution, operation and effect of the invention according to claim 1 are as follows.

[Structure] A protective film and a polarized light separating plate are provided, and a corner of the film is subjected to a curved chamfering treatment.

According to the above arrangement, since the corners of the film are curved, the stress concentration on the corners of the film when the corners of the film collide with another object can be reduced. Separation between adjacent film layers of the polarization separation plate is less likely to occur. This can be confirmed from the experimental results described below.

[Effect] Accordingly, it is possible to provide an optical film capable of suppressing the problem of delamination at the polarized light separating plate portion from the corner of the film and improving the yield.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 and 2 show the optical film A. FIG.

This optical film A is obtained by laminating a protective film 3 made of PE (polyethylene) material, a polarization separation plate 2, an adhesive layer 4, a linear polarizing plate 1, an adhesive layer 5, and a release film 6 in this order. With the configuration, the radius of curvature R of the film corner is 1
mm chamfered.

The optical film A is cut into a rectangular shape from a single laminated film with a cutting blade such as a Thomson blade (at this time, the curved surface is also cut by the cutting blade).

Next, the polarized light separating plate 2 of the conventional optical film in which the corner portion of the film is not curved and the optical film A of the present invention in which the curved surface is treated (referred to as “this product” in the tables and the like) are used. Inspection results of the evaluation of delamination of the above are described.

In the table, R is the radius of curvature of the film corner, and L is the length of the diagonal line of the film. "Depth" is the length of the peeled portion from the vertex of the film corner.

[0019] Non-defective rate calculation in Table 1 (non-defective rate = non-peeled product / number of inspections) 10 inches (this product) 128/133 ９６ 96.2% 14 inches (conventional product) 101/189 ５３ 53.4% Non-defective rate calculation in Table 2 (non-defective rate = non-peeled product / number of inspections) This product 104/110 ９４ 94.5% Conventional product 18/15 ５３ 53.3% Conventional product 2 11/15 ７３ 73.3% Conventional Product 3 10/15 ≒ 66.7% In the conventional product, the non-defective product ratio is about 53 to 73%, whereas in the optical film according to the present invention, the curvature radius R of the film corner is 1.0 mm or 0.5 mm. Good product rate is 94-9
It was 6%, and it was confirmed that peeling of the film could be suppressed and the yield could be improved by performing a chamfering process on the corner of the film to have a radius of curvature R.

Considering the ease of processing, the shape of the corners of the object to be stuck, the effect of preventing peeling, etc., the R is 0.5 mm.
It is considered that a better effect can be obtained when the thickness is 1.0 mm, and a still better effect can be obtained when R = 0.7 mm.

As described above, by performing the chamfering process on the corner of the film, it is possible to suppress the occurrence of the trigger of the peeling of the film due to the collision or contact with another object. Accordingly, the problem that the polarization separation plate 2 also peels off can be suppressed, and the yield can be improved.

[Another Embodiment] The corner portion of the optical film A may be subjected to a curved surface processing into an elliptical surface or another curved surface.

After cutting the optical film A into a predetermined shape (in the above embodiment, after cutting into a rectangle), a corner portion of the film may be subjected to a curved chamfering process.

The optical film A may be a film in which a protective film, a polarization separating plate, a linear polarizing plate, an adhesive layer and a release film are directly laminated in this order, or a T film may be formed between adjacent films.
The film may be indirectly laminated with another film layer such as an AC film (triacetyl cellulose film) interposed therebetween.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing a laminated structure of an optical film having a polarization separation plate.

FIG. 2 is an enlarged plan view of a main part showing a curved corner of a film corner;

[Explanation of symbols]

 2 Polarization separation plate 3 Protective film

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Claims (1)

[Claims] 1. An optical film comprising a protective film and a polarizing beam splitter, wherein a corner portion of the film is subjected to a curved chamfering treatment.