JPH08278404A - Lens sheet and its production - Google Patents

Abstract

PURPOSE: To improve the accuracy in the arrangement of lenses in a parallel direction and to improve the productivity of a lens sheet by forming the lens part on the top and back surfaces in such a manner that each lens part consists of a periodic ruggedness pattern in one direction and the directions of ruggedness patterns on the top and back surfaces cross each other. CONSTITUTION: After a UV-curing resin 2 is applied on both surfaces of a transparent film 1 having transmitting property for UV rays, the film 5 is passed through between a pair of forming rolls 4a, 4b each having a stamper 3a, 3b of a desired form, respectively, attached to the roll surface so that the resin layers on both surfaces of the film are deformed according to the form of the stampers 3a, 3b. Then the film 5 after passed through the forming rolls 4a, 4b is irradiated with UV rays to cure the both resin layers in an uncured state. In this case, the forming surface of the stamper 3a, 3b has a ruggedness pattern of a desired form (reversed form of the lens to be formed) and the rugged pattern is continuous and periodic in one direction. The directions of the periodic patterns on the top and back surface are different from each other. As for the stamper 3a, 3b, a metal such as copper and brass or a nonmetal material can be used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens sheet used for optical lenses, projection screens and the like, and a method for manufacturing the same. The lens sheet referred to in the present invention is typified by a lenticular, a linear Fresnel, and the like, and one surface (both surfaces) is provided with projections and depressions of a predetermined shape that form a lens, and a projection type television or It is used as an optical component such as an overhead projector (OHP).

[0002]

2. Description of the Related Art Heretofore, the following methods have been known as typical methods for molding this type of lens sheet.

Pressing method A thermoplastic resin is pressed using a heated stamper,
A method of molding the lens surface.

Casting method A method in which a melted and softened thermoplastic resin is applied or injected onto the uneven surface of a stamper and the resin is solidified to mold the lens surface.

Further, in recent years, a method of manufacturing a lens sheet using not such a thermoplastic resin but a resin of a type that is cured by irradiation of radiation represented by ultraviolet rays (UV) and electron beams (EB), etc. There are various proposals regarding the above, but the following is known as a method for molding both front and back surfaces.

Japanese Laid-Open Patent Publication No. 1-159627 discloses a method for coating both surfaces of a transparent film with an ultraviolet curable resin,
Production of a screen having a lenticular lens on both sides by passing the film between a pair of rolls having a stamper mounted on the surface to form the resin part, and then irradiating ultraviolet rays to cure the formed resin. Method.

In the product manufactured by the above method, the cylindrical lenses on both the front and back sides have the same parallel direction (parallel to the axial direction of the roll surface), and the lens shapes are different on the front and back sides (for example, in the orthogonal direction). Until now, no specific method has been reported for producing the lens sheets arranged side by side.

In order to manufacture the lens sheet as described above, lens sheets having a lens portion formed on only one surface are separately molded for the front and back surfaces, and the respective lens sheets are flat surfaces (non-lens portion Method of bonding on the forming surface).

A flat press method in which stampers are arranged on the upper and lower surface plates of a press machine, and an intermediate thermoplastic resin is pressed by them to mold both surfaces of the resin. And so on

According to the above method, not only the number of "bonding" steps is increased and the productivity is lowered, but also the parallel direction of the cylindrical lenses on the front and back sides (for example, when they are orthogonal) is accurately adjusted (correctly to 90 °). ) It is difficult to attach them.

Even with the above method, it is difficult to dispose the stampers of the upper and lower surface plates with respect to each other with high precision, and since the stamper used is a mold, its shape is likely to be restricted. Furthermore, the problem that "energy and time required for molding are large" depending on the molding itself of the thermoplastic resin by the flat pressing method still remains.

[0012]

The present invention is based on the above-mentioned 2
There are two issues, namely, (1) improving the arrangement accuracy of the front and back lens groups in the parallel direction. (2) Improve the productivity of lens sheets. It is an object of the present invention to provide a lens sheet having a configuration for solving the above and a manufacturing method thereof.

[0013]

That is, according to the present invention of claim 1, a lens portion having a predetermined shape is formed by a cured product of a radiation curable resin on both surfaces of a transparent film or a transparent sheet having a radiation transmitting property. In the lens sheet described above, each of the front and back lens portions is composed of periodic concavities and convexities arranged in one direction, and the juxtaposed directions of the concavities and convexities are orthogonal to each other.

According to a second aspect of the present invention, the lens portions on the front and back sides are (a) a cylindrical lens having semi-cylindrical convex lenses arranged in parallel.
Lens group. (B) A cylindrical lens group in which semi-cylindrical concave lenses are arranged in a direction orthogonal to the direction in which the lens groups in (a) are arranged. It is characterized by consisting of a combination of.

According to a third aspect of the present invention, a step of applying a radiation curable resin on both surfaces of a transparent film or a transparent sheet having a radiation transmitting property, and a stamper having a predetermined shape of concavo-convex forming a reverse mold of a lens are formed. Between a pair of rolls having on the surface, through the transparent film or transparent sheet obtained in the above step, a step of molding the resin on both sides into a shape corresponding to the unevenness of the stamper, and the radiation to the molded resin. A step of irradiating and curing, and a stamper having a pair of rolls on its surface, comprising: (a) a stamper in which periodic irregularities are juxtaposed in the axial direction of the roll surface. (B) A stamper in which periodic concavities and convexities are juxtaposed in the outer peripheral direction of the roll surface. It is characterized by consisting of a combination of.

According to a fourth aspect of the present invention, the stamper of any one of (a) and (b) is a lenticular plate in which semi-cylindrical convex lenses are arranged side by side and made of a thermoplastic resin press-molded using the stamper. It is a manufacturing method of the lens sheet according to claim 3 characterized by things.

The transparent film or transparent sheet that transmits radiation is not particularly limited in material, but may be synthetic resin such as methacrylic resin, polycarbonate resin, vinyl chloride resin, polystyrene resin, polyolefin resin, or composites thereof, or glass. Are used.

In the present invention, among others, PET and A-
PET (polyethylene terephthalate), PVC (polyvinyl chloride), PC (polycarbonate), PMMA
(Polymethylmethacrylate) and the like are preferable, and a radiation-curable resin is subjected to an easy adhesion treatment, if necessary.

Hereinafter, a lens sheet using an ultraviolet curable resin and a method for manufacturing the same will be described with reference to the drawings.

FIG. 1 is an overall configuration diagram of a lens sheet manufacturing apparatus, FIG. 2 is an explanatory diagram showing a pair of molding rolls, FIG. 3 is a sectional explanatory diagram showing an example of the produced lens sheet, and FIG. 4 is another example. FIG. 5 is an overall configuration diagram of a lens sheet manufacturing apparatus, and FIG. 5 is an explanatory diagram showing an example of a set of stampers used.

As shown in FIG. 1, the lens sheet manufacturing apparatus of this embodiment is roughly divided into an ultraviolet-curable resin coating section and
It consists of a molding part and an ultraviolet irradiation part.

After the ultraviolet curable resin 2 is applied and formed on both surfaces of the transparent film 1 having ultraviolet transparency, a pair of molding rolls 4 (4a, 4b) having stampers 3 (3a, 3b) of a desired shape mounted on the surfaces thereof are formed. The film 5 (having resin layers formed on both sides) is passed between the two) to deform the shape of the resin layers on both sides according to the shape of the stamper. Next, the film 5 that has passed between the molding rolls 4 is irradiated with ultraviolet rays by the ultraviolet irradiation lamp 6 (6a, 6b) to cure the resin layers on both sides in the uncured state. Note that the same constituent requirements for the front and back sides will be represented by the subscripts a and b.

The coating thickness of the ultraviolet curable resin 2 on the transparent film 1 depends on the shape of the lens to be molded, but a thickness of 50 to 500 μm on one side is suitable. Further, the coating thickness also depends on the supply rate of the transparent film and the viscosity of the resin.

As a coating method, a coating method such as a doctor blade method, a roll coating method or a hanger die coating method, and various printing methods are appropriately adopted.

On the molding surface of the stamper 3 (3a, 3b),
Concavities and convexities of a desired shape (reverse type of the lens shape to be molded) are formed, and in the present invention, the concavo-convex shapes that are periodically continuous in one direction have different directions on the front and back sides.

FIG. 2 shows a pair of molding rolls 4 (4a, 4b) on which the stampers 3 (3a, 3b) are mounted on the surface so that the uneven shapes are juxtaposed in different directions on the front and back sides as described above. .

The stamper 3 may be made of metal such as copper or brass, or non-metal material such as glass, silicone resin, epoxy resin, urethane resin or the like.

When the lens sheet having the cross-sectional shape shown in FIG. 3 is molded by the stamper with respect to the one-sided shape shown in FIG. 3B, the reverse stamper has a surface in which semi-cylindrical projections are arranged in parallel. Will have. In order to cut into the above-mentioned shape with a die, a cutting tool having the tip shape of a semi-cylindrical recess must be used, but the above-mentioned die cannot be obtained because the cutting is practically difficult. .

Therefore, a thermoplastic resin sheet is emboss-molded by a stamper having a surface in which semi-cylindrical concave portions are arranged in parallel so that a mold can be easily obtained (the semi-cylindrical convex portions have a surface in parallel shape). ) Is used as a stamper.

Molding into an uncured UV-curable resin (prepolymer) allows the resin layer to be deformed without requiring heating energy and pressurizing energy. Even a molded resin sheet (hereinafter referred to as a resin stamper) can sufficiently function as a stamper.

As the material of the resin stamper, polyacetal resin, polyarylate resin, polyetherketone resin, polyethersulfone resin, norbornene resin, polyethylene terephthalate resin, polycarbonate resin or the like is used.

A lens sheet manufacturing apparatus having the structure shown in FIG. 4 can also be used. The difference from the manufacturing apparatus of FIG. 1 is that the ultraviolet irradiation unit is not provided on both downstream surfaces that have passed through a pair of molding rolls, but is provided on each molding roll one by one. The point is that the resin is cured.

The film 5 first contacts the stamper 3a on the surface of the roll 4a to mold (deform) the ultraviolet curable resin 2 on that surface. UV lamp 6a through the film 5
When ultraviolet rays are radiated by, only the resin 2 on the molded side is cured. Since the resin on the opposite side faces the air, oxygen in the air impedes the resin curing. Except for exceptional UV curable resins, the presence of oxygen normally hinders resin curing during UV irradiation, so that the manufacturing apparatus with the configuration shown in FIG. 4 can be manufactured in the same manner as in FIG. is there.

[0034]

The function is continuous molding of the radiation-curable resin by roll pressing, and the resin curing is performed only by irradiation of radiation, so that the productivity is very good. At the same time, the directions of the front and back lens surfaces can be controlled when the stamper is mounted on the roll surface, so that strict control is possible. (Corresponding to claim 3)

Since the lens portion is molded by the radiation curable resin instead of the thermoplastic resin, a long molding time is not required and energy (pressurizing energy) required for molding (deforming) the resin is also generated. I don't need much. Therefore, the stamper to be used does not have to be a metal mold, and may be a resin stamper, and the shape of the molding surface is less subject to restrictions in manufacturing the stamper as the metal mold is.
(Corresponding to claim 4)

[0036]

Embodiments of the present invention will be described below.

The surface of the metal roll is cut by a lathe by a threading method using a general-shaped (rounded blade) bite to obtain a lenticular forming roll 4a having a sectional shape shown in FIG. 5 (a). Pitch: 0.3 mm, curvature: 0.19 mm, depth: 0.
07 mm. Roll width (axial length); 700 mm, roll diameter; 2
00 mm.

It has the same shape as that shown in FIG.
0.1 mm, curvature; 0.27 mm, depth; 0.01 mm
The lenticular molding roll of No. 3 is prepared, and 300 μm thick polymethylpentene film (trade name; TPX, manufactured by Mitsui Petrochemical Co., Ltd.)
The film is heat embossed at ℃ and the lenticular shaped film is used as a resin stamper.

The resin stamper is wound around a surface of a metal roll having a width (axial length) of 500 mm and a diameter of 200 mm to be mounted to form a molding roll. The method of winding the resin stamper is such that the periodic unevenness (cylindrical shape) formed on the stamper is arranged so as to be parallel in the circumferential direction on the surface of the roll, as shown in FIG.
Forming roll 4b. The cross-sectional shape of the roll is shown in FIG.
It shows in (b).

As the manufacturing apparatus, the one having the structure shown in FIG. 4 is adopted. A urethane-acrylic UV-curable resin (manufactured by Nippon Kayaku Co., Ltd.) was adjusted to a viscosity of 2500 CP and subjected to vacuum defoaming treatment, and then polyvinyl chloride (PV
C) A film (trade name; Emron, manufactured by Morino Kako) is coated on both sides with a thickness of 200 μm.

The above-mentioned pair of molding rolls 4 (4a, 4b)
In the meantime, the film 5 is passed at a feed rate of 2 m / min.

The film 5 first contacts the stamper 3a on the surface of the roll 4a to mold (deform) the ultraviolet curable resin on that surface. At the same time, ultraviolet rays are emitted from the ultraviolet lamp 6a through the film 5 (output: 120 W
/ Cm), and only the resin 2 on the molded side is cured.

Next, the molding roll 4b on the downstream side is also subjected to similar molding to ultraviolet irradiation to cure the resin 2 on the opposite side to obtain a lens sheet having the structure shown in FIG.

Needless to say, the configuration is not limited to the above-mentioned embodiment and may be modified without departing from the spirit of the invention.
For example, instead of using a lenticular shape (semi-cylindrical concave portions or convex portions juxtaposed), a stamper having a V-shaped cross section is used.

The lens sheet produced according to the present invention is suitable for use as a reflection type projection screen.

For example, one side of the cylindrical surface (semi-cylindrical convex lens group) is directed toward the observer so that the parallel direction of the convex lens groups is horizontal, and a light reflecting layer is formed on the back surface (metal vapor deposition or ink). Application).

When the screen is used, the horizontal reflecting direction can be controlled by the observer side cylindrical surface, and the vertical reflecting direction can be controlled by the unevenness of the reflecting surface.

[0048]

The remarkable effects of the present invention are listed below. 1) The direction of the front and back lens surfaces can be controlled when the stamper is mounted on the roll surface, so that strict control is possible, and therefore, the arrangement accuracy of the front and back lens groups in the parallel direction is improved. 2) The radiation-curable resin is continuously molded by a roll press, and the resin curing is performed only by irradiation of radiation, so that the productivity of the lens sheet is improved. 3) The shape of the molding surface is rarely restricted by the stamper.

[0049]

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a lens sheet manufacturing apparatus.

FIG. 2 is an explanatory view showing a pair of molding rolls.

FIG. 3 is an explanatory cross-sectional view showing an example of a lens sheet.

FIG. 4 is an overall configuration diagram of another lens sheet manufacturing apparatus.

FIG. 5 is an explanatory diagram showing an example of a set of stampers used.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Transparent film having radiation (ultraviolet) transparency 2 ... Radiation (ultraviolet) curable resin 3 ... Stamper 4 ... Molding roll 5 ... Transparent film having resin layers formed on both sides 6 ... Radiation (ultraviolet) irradiation lamp

Claims (4)

[Claims] 1. A lens sheet comprising a transparent film or a transparent sheet having radiation transparency and lens parts having a predetermined shape made of a cured product of a radiation curable resin formed on both sides of the lens sheet. A lens sheet, which comprises periodical concavities and convexities arranged in parallel, wherein the concavities and convexities of the concavities and convexities are orthogonal to each other on the front and back sides. 2. The lens sheet according to claim 1, wherein the front and back lens portions are composed of the following combination (a) and (b). (A) Cylindrical with semi-cylindrical convex lenses
Lens group. (B) A cylindrical lens group in which semi-cylindrical concave lenses are juxtaposed in a direction orthogonal to the juxtaposed direction of the lens groups in (a). 3. A step of applying a radiation curable resin on both sides of a transparent film or a transparent sheet having a radiation transmitting property, and a pair of stampers on the surface of which concaves and convexes of a predetermined shape which form an inverted mold of a lens are formed. Through the transparent film or transparent sheet obtained in the above step between the rolls, and molding the resin on both sides into a shape corresponding to the unevenness of the stamper; and irradiating the molded resin with radiation to cure it. ,
In the method of manufacturing a lens sheet including and, a stamper having a pair of rolls on its surface has the following (a)
A method of manufacturing a lens sheet, comprising the combination of (b). (A) A stamper in which periodic concavities and convexities are arranged side by side in the axial direction of the roll surface. (B) A stamper in which periodic concavities and convexities are juxtaposed in the outer peripheral direction of the roll surface. 4. The stamper according to any one of (a) and (b) above,
The method of manufacturing a lens sheet according to claim 3, wherein the lens sheet is a lenticular stamper in which semi-cylindrical convex lenses made of a thermoplastic resin press-molded using the stamper are arranged in parallel.