JP2001356208A - Optical film with rugged pattern and planar light source element member using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical film with a rugged pattern on the surface which can easily be integrated with another member without providing an adhesive layer. SOLUTION: The optical film has a rugged pattern formed on the surface with a resin which exhibits adhesion when irradiated with ionizing radiation. The resin has a function to cause a reversible and quick phase transition under a temperature change and the phase transition is preferably a sol-gel phase transition. When the optical film is disposed on a light guide member and integrated with it by irradiation with UV, the objective planar light source element member is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical film and a surface light source element member using the optical film.

[0002]

2. Description of the Related Art A transmissive display device represented by a liquid crystal panel includes a surface light source element (backlight) that emits light in a planar manner,
A display panel in which pixels are arranged in a dot shape,
Characters and images are displayed by controlling the light transmittance of each pixel of the display panel. As a backlight, a distribution of luminance of emitted light is controlled by combining a halogen lamp, a reflector, a lens, and the like. A fluorescent tube is provided on an end surface of a light guide, and light from the fluorescent tube is perpendicular to the end surface. And a fluorescent tube provided inside a light guide, and the like. A backlight using a halogen lamp is mainly used for a liquid crystal projector requiring high luminance. On the other hand, since a backlight using a light guide can be made thin, a direct-view liquid crystal T
V and are often used for personal computer displays.

In a backlight used for a liquid crystal TV, a notebook personal computer, and the like, it is required to reduce power consumption and to have high luminance. Higher luminance can be realized by increasing the number of light sources such as cold cathode tubes, but this method is not practical because it leads to an increase in power consumption. Therefore, a surface light source element has been proposed in which a microprism array film is arranged on a light guide, and total light reflection on the wall surface of the microprism array is used to reduce light loss and realize high brightness. (See US Pat. No. 5,396,350).

[0004]

In a surface light source device having a structure in which a microprism array film is disposed on a light guide, it is necessary to bond the light guide to the microprism array film, and the thickness of the adhesive layer is increased. However, there arises a problem that the thickness of the surface light source element is increased to lower the light transmittance and that the number of working steps is increased.

The present invention has been made in view of the above problems, and does not require a separate adhesive layer, can be easily integrated with other members, and can be used for a surface light source element or the like. It is another object of the present invention to provide an optical film having an uneven pattern on the surface.

[0006]

The optical film having a concavo-convex pattern on the surface of the present invention, which solves the above-mentioned problems, has a concavo-convex pattern formed on the surface by a resin that exhibits adhesive performance when irradiated with ionizing radiation. It is characterized by being. In this specification, a film and a sheet are not distinguished from each other, but are described as a film including both.

The above resin has a function of causing a reversible and rapid phase transition by a temperature change, and the fact that the phase transition is a sol-gel phase transition turns a resin in a gel state at ordinary temperature into a sol. After raising the temperature to give the resin fluidity, pour it into a mold having a pattern with a predetermined concavo-convex pattern inverted, gel it by cooling, and then release it to form a mold on the resin surface. This is preferable in that the uneven pattern can be precisely shaped. At the time of release, the above resin is in a gel state, but does not exhibit adhesive properties until irradiation with ionizing radiation, so that the optical film can be released easily without breaking the uneven pattern.

In order to develop the sol-gel phase transition,
It is effective to add a mixture of a polymethacrylic ester containing a large amount of isotactic component and a polymethacrylic ester containing a large amount of syndiotactic component to the resin.

A surface light source element member is formed by integrating the optical film and the light guide. After overlapping the optical film and the light guide, by irradiating with ionizing radiation, the concavo-convex pattern formed on the optical film exhibits an adhesive property, without separately providing an adhesive layer, the optical film And the light guide can be integrated.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The cross-sectional shape of the convex portion of the concavo-convex pattern provided on the optical film of the present invention is arbitrary such as parabolic or triangular. The uneven pattern may be one-dimensional provided in only one direction or two-dimensional provided in two directions. When a support needs to be provided on the back surface of the optical film, a film made of an acrylic resin, a polycarbonate resin, a vinyl chloride resin, a cellulose triacetate resin, a polyester resin, or the like may be laminated.

FIG. 1 is a schematic structural view of a surface light source element using a surface light source element member according to the present invention. This surface light source element is provided with a light guide 1 provided with a light source 2 such as a cold cathode tube at both ends, and a microprism array-like uneven pattern for controlling the angular distribution of light emitted from the light guide 1. Optical film 3 provided. The ridgeline of the convex part of the optical film 3 is arranged so as to be parallel to the light guide end face on the side where the light source is arranged. A light guide 1 is provided around the light source 2.
A reflector that reflects light traveling in the direction opposite to the end surface of the light guide 1 and travels in the direction of the end surface of the light guide 1 is provided. Light incident on the light guide 1 from the end face propagates in the light guide while repeating total reflection. This propagating light is taken into the optical film 3 from a contact portion between the convex portion of the optical film 3 and the emission surface of the light guide 1. Accordingly, light propagating in the light guide 1 is sequentially extracted from the contact portion to the optical film 3, and the extracted light is condensed and emitted while being totally reflected in the projections of the optical film 3.

The same configuration as the surface light source element shown in FIG.
It is known from SP 5,396,350 and the like. The optical film 3 of the present invention is applied to the light guide 1 with an appropriate laminator pressure.
Is irradiated with ionizing radiation in a state where the light guide is pressed, the convexity of the optical film exhibits adhesive performance, and the light guide 1 and the optical film 3 are bonded to each other, whereby the light guide and the optical film are bonded. It is not necessary to provide an intermediate layer made of an adhesive, a pressure-sensitive adhesive or the like between them. Thereby, the process can be simplified, and the light transmittance does not decrease due to the adhesive layer. An image display device can be configured by using a surface light source element using the optical film of the present invention as a backlight and providing a transmissive display element on an emission surface thereof. As the transmission type display element, STN, TFT, M
And a liquid crystal panel such as INI.

[0013]

The present invention will be described below in detail with reference to examples.

(Example 1) Acrylic monomers, acrylic acid, butyl acrylate and 2-ethylhexyl acrylate were mixed at 10 parts by weight, 80 parts by weight and 10 parts by weight, respectively. To this mixture, 0.2 parts by weight of hexanediol diacrylate as an acrylic crosslinking agent was added. Further, an acetophenone-based ultraviolet polymerization initiator Darocur 1173 (Ciba Ge)
iggy) (5 parts by weight). As a result, an acrylic ultraviolet irradiation type pressure-sensitive adhesive precursor was obtained. Polymethyl methacrylate containing a large amount of isotactic component and polymethacryl containing a large amount of syndiotactic component so that the acrylic ultraviolet irradiation type pressure-sensitive adhesive precursor undergoes reversible and rapid sol-gel phase transition due to temperature change. The resin used for the optical film of the present invention was obtained by adding 5 parts by weight of a mixture with methyl acid.

The resin is heated to 100 ° C. to form a sol, and the resin is poured into a nickel mold having a microprism array having a reversed concavo-convex pattern. Then, a transparent PET film is formed on the resin layer. (Support). After gelling by cooling the resin filled in the nickel mold, it is released from the nickel mold,
The microprism array-shaped concavo-convex pattern was precisely shaped. The optical film thus obtained was laminated on an acrylic light guide at a predetermined pressure, and ultraviolet light was irradiated from the PET film side. Through the above steps, a surface light source element member was obtained in which the optical film provided with the microprism array-shaped concavo-convex pattern and the light guide were integrated.

[0016]

According to the present invention, it is possible to obtain an optical film having a concavo-convex pattern on its surface, which can be easily integrated with other members without separately providing an adhesive layer.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an example of a surface light source element using an optical film of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Light guide 2 ... Light source 3 ... Optical film

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Claims (6)

[Claims] 1. An optical film, wherein an uneven pattern is formed on a surface of a resin that exhibits adhesive performance when irradiated with ionizing radiation. 2. The optical film according to claim 1, wherein the resin exhibiting adhesive properties when irradiated with ionizing radiation has a function of causing a reversible and rapid phase transition by a temperature change. 3. The optical film according to claim 2, wherein the reversible and rapid phase transition due to a temperature change is a sol-gel phase transition. 4. The sol-gel phase transition is developed by adding a mixture of a polymethacrylate ester rich in isotactic component and a polymethacrylate ester rich in syndiotactic component. 3. The optical film according to 3. 5. A surface light source element member in which the optical film according to claim 1 and a light guide are integrated. 6. After the optical film according to claim 1 and a light guide are superimposed, by irradiating with ionizing radiation,
6. The method for manufacturing a surface light source element member according to claim 5, wherein the concave / convex pattern formed on the optical film exhibits an adhesive property, and the optical film and the light guide are integrated by the adhesive force.