JPH09258011A - Lens sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a lens sheet having good weatherability by forming ruggedness constituting a lens part on one surface of a transparent supplying body by the cured matter of a radiation-curing resin and forming a protective layer contg. a UV absorbent on the other surface of this supporting body. SOLUTION: The ruggedness constituting the lens parts 1 (lenticular sheet on which a cylindrical lens group is formed) is formed on one surface of the transparent supporting body 2 by the cured matter of the radiation curing resin. A protective film 3 contg. a UV absorbent is formed on the other surface (the side used as a transmission type screen) of the transparent supporting body 2 or on the front surface (the side used as a lenticular display) of the lens parts 1. As a result, the problem of the deterioration in the performance that the lens sheet consisting of the cured matter of the UV (electron beam) curing resin is discolored (yellowed) by the influence of the UV rays included in external light (sunshine and illumination light) in the use environment is solved and the lens sheet having the good weatherability is obtd.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a lens sheet represented by a Fresnel lens sheet or a lenticular sheet.

[0002]

2. Description of the Related Art The above lens sheet is manufactured by press-molding a transparent thermoplastic resin sheet or by molding at the same time as melt extrusion. Pitching is very difficult. The reason for this is that the temperature is non-uniform at the time of cooling after thermoforming, and the molded product is warped or the heat shrinkage is non-uniform.

In recent years, liquid crystal projection televisions have come into widespread use, and a transmissive screen for observing the image is required. Since the number of pixels of the liquid crystal projector is increasing with the increase in the definition of the image quality, the lenticular sheet is required to have a fine pitch for the cylindrical lens. Specifically, the current 0.7 m
A fine pitch of 0.3 mm or less is required from around m.

As a manufacturing method suitable for molding a fine-pitch lens sheet, ultraviolet rays (or electron beams) are used.
Various molding methods using a curable resin are known, and the proposals exemplified below are representative. By using an ultraviolet (electron beam) curable resin, it is possible to achieve a fine pitch that cannot be achieved with a molded product made of a thermoplastic resin, and a lenticular sheet with a fine pitch up to a minimum pitch of 50 μm can also be manufactured.

JP, 61-177215, A A UV-curable resin is injected into the gap between the Fresnel mold and the transparent resin plate and irradiated with ultraviolet rays to polymerize and bond the transparent resin plate and the transparent resin plate. And an ultraviolet curable resin having a Fresnel lens surface on the side of the anti-transparent resin plate (and a method for producing the same).

JP, 63-134227, A After applying an ultraviolet (electron beam) curable resin to a Fresnel die, the film is laminated on the resin while defoaming,
After molding by irradiation with ultraviolet rays (electron beams), the film (and resin) is released, and then integrated with the transparent substrate.

Ultraviolet rays (electron beam) represented by the above proposal
A lens sheet made of a cured product of a curable resin has a problem of performance deterioration such as discoloration (yellowing) due to the influence of ultraviolet rays contained in outside light (sunlight or illumination light) under a use environment.

[0008]

SUMMARY OF THE INVENTION The present invention is intended to solve the above problems, and an object thereof is to provide a lens sheet having good weather resistance.

[0009]

According to a first aspect of the present invention, there is provided a lens sheet in which irregularities constituting a lens portion are formed by a cured product of a radiation curable resin on one surface of a transparent support, wherein the support is provided. The lens sheet is characterized in that a protective layer containing an ultraviolet absorber is formed on the other surface of the lens sheet.

According to a second aspect of the present invention, in a lens sheet in which irregularities constituting a lens portion are formed on one surface of a transparent support by a cured product of a radiation curable resin, the surface of the lens portion absorbs ultraviolet rays. It is a lens sheet having a structure in which a protective layer containing an agent is formed.

According to a third aspect of the present invention, the protective layer further comprises a diffusing agent.
Alternatively, the lens sheet according to claim 2.

As the transparent support, a resin film (sheet) having good light transmittance can be used, and examples thereof include acrylic resin, polycarbonate resin, polyester resin, and the like. From the viewpoint, polycarbonate resin is preferable.

As the radiation (ultraviolet) curable resin, generally used epoxy acrylate type, urethane acrylate type and the like are used.

The film that serves as the base of the protective layer is
A fluorine film or a two-layer film in which a fluorine resin and an acrylic resin are combined can be used, and a polyester film having a colored translucency can also be used. Particularly, from the viewpoint of weather resistance and cost, a two-layer film formed by co-extruding a fluororesin and an acrylic resin is preferable.

A lens sheet (lenticular sheet)
For example, when using it for a transmissive screen,
Image the projected light from the target (or
It is necessary to form a diffusion layer to expand the field angle)
Diffusing agent (SiO_Two, Al_TwoO _Three, CaCO_ThreeSuch as inorganic
Quality film) on the lens sheet.
It is being done. In this case,
The protective layer contains a diffusing agent, and the protective layer also functions as a diffusing agent film.
By doing so, the layer structure of the lens sheet can be simplified.
To be categorized. (Corresponding to claim 3)

Further, in order to prevent reflection due to external light from the observer side and to improve the contrast of an image to be observed, a smoke film having a colored translucent property is laminated on a lens sheet. .

In any case, when the lens portion faces the observer side and the protective layer containing the ultraviolet absorber is formed on the surface thereof, the lens portion is placed so as not to impair the optical characteristics of the lens portion. It is necessary to prevent the unevenness that is formed from being filled with the protective layer. (Corresponding to claim 2; see FIG. 2)

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a sectional explanatory view showing a configuration of a lens sheet corresponding to claim 1, and FIG. 2 is a sectional explanatory diagram showing a configuration of a lens sheet corresponding to claim 2.

On one surface of the transparent support 2, the irregularities (the lenticular sheet in which the cylindrical lens group is formed in the figure, which constitutes the lens portion 1 are not limited thereto, but the radiation curable resin is used. The ultraviolet absorber is formed on the other surface of the transparent support 2 (FIG. 1; usage as a transmissive screen) or the surface of the lens portion 1 (FIG. 2; usage as a lenticular display). It is the structure in which the protective film 3 including is formed.

A lens sheet having a structure in which the transparent support 2 and the lens portion 1 made of a cured product of a radiation curable resin are laminated and combined can be manufactured by an existing method. The protective film 3 is laminated (heat-bonded) on the desired side of the lens sheet while being heated and pressed according to the purpose of use, but may be bonded via a pressure-sensitive adhesive, if necessary. . Further, in the case of the configuration of FIG. 2, it is not necessary to adhere the protective film 3 to the entire surface of the lens sheet, and it is also possible to simply join the protective films.

[0021]

EXAMPLE A polycarbonate resin was used as the transparent support 2, and a lens sheet having a constitution in which a lens portion 1 made of a cured product of a urethane acrylate-based UV curable resin was laminated and combined, and a fluorine resin and an acrylic resin were used as a protective film 3. A two-layer film (including an ultraviolet absorber) formed by co-extrusion with a resin was used to prepare a lens sheet having the configuration shown in FIG.

When the lens sheet was irradiated with ultraviolet light from the protective film 3 side for 50 hours, no performance deterioration due to yellowing of the lens part 1 was observed. The irradiation with ultraviolet light was performed in accordance with the apparatus specified in JIS B 7753 (Sunshine carbon arc lamp type weather resistance tester).

Under the same conditions, the curve (c in FIG. 3) showing the light transmittance after irradiating the lens sheet having the constitution in which the protective film 3 is not formed with the ultraviolet light for 50 hours and the protective film 3 are A curve (a in FIG. 3) showing the light transmittance of the lens sheet (before irradiation of ultraviolet light) having a structure not formed is also shown in FIG. 3 as comparison data. The data according to this example (measured by peeling the protective film 3 after irradiation with ultraviolet light) is b in FIG.

As is clear from the comparison in FIG. 3, b and c
And, the light transmittance at about 300 to 450 nm is different, and the effect of the presence or absence of the protective film 3 is remarkable.
Of the wavelengths in the visible region (400 to 700 nm),
If the light transmittance in the region of 400 to 450 nm is low, the lens sheet will turn yellow, which is a complementary color of the wavelength of the region.

[0025]

According to the present invention, a lens sheet made of a cured product of an ultraviolet (electron beam) curable resin is discolored (yellow) under the environment of use due to the effect of ultraviolet rays contained in outside light (sunlight or illumination light). The problem of deterioration in performance was solved, and a lens sheet having good weather resistance was provided.

[0026]

[Brief description of drawings]

FIG. 1 is a cross-sectional explanatory view showing an example of a lens sheet of the present invention.

FIG. 2 is a sectional explanatory view showing another example of the lens sheet of the present invention.

FIG. 3 is a graph showing a comparison of light transmittances of lens sheets.

[Explanation of symbols]

 1 ... Lens part 2 ... Transparent support 3 ... Protective layer

Claims (3)

[Claims] 1. A lens sheet in which irregularities constituting a lens portion are formed of a cured product of a radiation curable resin on one surface of a transparent support, wherein a protective layer containing an ultraviolet absorber is provided on the other surface of the support. A lens sheet having a formed structure. 2. A lens sheet in which irregularities constituting a lens portion are formed by a cured product of a radiation curable resin on one surface of a transparent support, wherein a protective layer containing an ultraviolet absorber is formed on the surface of the lens portion. A lens sheet having the above described configuration. 3. The lens sheet according to claim 1, wherein the protective layer further comprises a diffusing agent.