JPH09311204A - Lenticular lens sheet and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a lenticular lens sheet to be used for a transmission type screen in such a manner that a fine rugged pattern which can not be obtd. by a conventional die molding method is formed on the lens surface, and to provide its production method. SOLUTION: Before the lenticular lens sheet 11 is formed by extrusion molding, a plastic film for molding having a fine rugged pattern 12 formed on its surface is prepared by using an ionizing radiation-curing resin. The film for molding is supplied between the molding die and the resin to be molded during the extrusion process. After the fused resin is cooled, the plastic film for molding is removed by peeling. Thus, the obtd. lenticular lens sheet has a fine rugged pattern 12 formed as one body.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lenticular lens sheet used for a screen of a so-called transmission type projection television which projects an image from the back side of the screen and observes the image from the front side. When configuring the screen,
The present invention relates to a lenticular lens sheet having a changeable optical characteristic and a manufacturing method thereof.

[0002]

2. Description of the Related Art Conventionally, a lenticular lens sheet used for a screen of a so-called transmissive projection television which projects an image from the back side and observes the transmitted image from the front is a diffusing agent in a transparent or translucent base resin. The resin base material kneaded with was manufactured by extrusion molding or press processing. This lenticular lens sheet has a linear lens having a circular or elliptical cross section on the incident light side, and a predetermined linear shape having a black stripe on the light outgoing side and a circular or elliptical cross section. A lenticular lens sheet integrally formed by alternately arranging lenses of some shapes in parallel was used. Alternatively, in some cases, a sheet having a fine concavo-convex shape and a base lenticular lens sheet placed on top of each other has been used.

The conventional transmissive screen using a lenticular lens sheet has a linear lens shape, so that it has a uniform width in outgoing light characteristics and a limit width in controlling outgoing light distribution with respect to incoming light at all angles. Was occurring. In order to solve this, it is conceivable to stack and use the sheets having the fine irregularities as described above, but the problems of light loss due to the two layers and the cost increase due to the increase of the materials are unavoidable. . In addition, a method of designing a fly-eye lens in advance is also conceivable, but in the current mold making technology, since the mold is ground and formed linearly or circumferentially with a bite-shaped blade, the present lenticular is used. There is a limit to the size of a lens, and it is very difficult to manufacture a mold by grinding a finer shape in accordance with a predetermined shape of optical design. Further, in the case of producing a mold by the method of engraving and polishing, the cost will increase enormously.

For example, on the incident light side of the lenticular lens, a part having a circular or elliptical cross section is formed as described above. This may be a semicircle of 0.1 mm to 0.2 mm, a quarter circle, or a semi-elliptical shape, but it is possible to accurately realize a more complicated fine shape. This is almost impossible with the current mold making technology. Therefore, even if an attempt is made to make the optical characteristics more complicated, only the means for changing the diameter of the circular or elliptical shape, the kind of the diffusing agent kneaded into the base material, and the concentration of the diffusing agent can be selected.

[0005]

SUMMARY OF THE INVENTION Therefore, the present invention
The present invention has been made to provide a lenticular lens sheet in which a fine concavo-convex shape, which has been impossible in the past, is formed on a base lenticular lens, and a manufacturing method thereof.
According to the present invention, it is possible to realize the one in which the fine concavo-convex shape is formed on the base lenticular lens sheet by a method different from the conventional one without requiring the mold to have higher precision than the conventional one. According to this lenticular lens sheet, excellent optical characteristics which cannot be obtained by the conventional sheet can be obtained.

[0006]

The lenticular lens sheet of the present invention which solves the above problems will be described below.
The lenticular lens sheet of the present invention has a structure in which fine irregularities are formed on the surface of the lenticular lens side portion of the portion corresponding to the conventional lenticular lens sheet serving as the base. In addition, the method of manufacturing the lenticular lens sheet of the present invention which solves the above problems will be described. First, in the method of manufacturing the lenticular lens sheet of the present invention, fine irregularities formed of a thermosetting resin are formed on the surface. A shaped plastic film is prepared.
For this, a transparent or semi-transparent plastic film is adhered to the surface of a mold roll on which fine irregularities have been formed while filling it with an ionizing radiation curable resin, and at the same time it is irradiated with ionizing radiation from the film side for thermosetting. By doing so, a shaped plastic film having fine irregularities formed on the film surface is formed. Secondly, at the time of molding the lenticular lens sheet, the shaped plastic film on which the fine concavo-convex shape is formed is supplied between the lenticular lens molds with the fine concavo-convex surface facing the thermoplastic resin surface side, and the plastic film and the lenticular lens substrate are provided. The sheet and the sheet are extruded together and molded. Thirdly, a step of peeling the shaped plastic film from the integrally extruded lenticular lens sheet substrate is performed. By sequentially performing the above, the lenticular lens sheet of the present invention can be manufactured.

Therefore, the invention according to claim 1 of the present invention is a lenticular lens sheet used for a transmissive screen, wherein a plurality of lenticular lens elements each having a lenticular lens shape on a light entrance surface are arranged in parallel in a plane. A lenticular lens sheet, which is characterized in that a fine concavo-convex shape is formed on the surface of each lens element while forming a lens plate. With such a configuration, a lens sheet having good light transmittance can be obtained instead of the conventional lenticular lens sheet in which a large amount of diffusing agent is kneaded.

Further, the invention of claim 4 of the present invention for solving the above-mentioned problems is as follows: (a) Press contact conveyance along the peripheral surface of a mold roll in which fine irregularities are engraved on the surface of the mold roll. A transparent or translucent plastic film to be formed, and a space formed by the concave portion of the mold roll is filled with an ionizing radiation curable resin at the time when the plastic film comes into contact with the mold roll. A step of irradiating ionizing radiation from the back surface of the plastic film to cure the ionizing radiation curable resin to produce a shaped plastic film in which fine irregularities are formed, and (b) the shape of a lenticular lens on at least one side. When the lenticular lens sheet is extruded and molded by extruding a thermoplastic resin between two mold rolls having concaves formed therein, Lum of fine irregularities, the step of contacting with fed along a mold roller in contact with the thermoplastic resin in the thermoplastic resin and the pressurized state, (c)
A method of manufacturing a lenticular lens sheet, which comprises sequentially performing the steps of cooling and solidifying a thermoplastic resin and then peeling off the shaped plastic film. It is in. By using such a manufacturing method, a lenticular lens sheet having a reduced amount of the diffusing agent and good light transmittance can be easily manufactured.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view and a sectional view of a lenticular lens sheet according to the present invention. FIG. 1A shows a perspective view of a lenticular lens sheet in which a convex fine lenticular lens shape is formed in parallel with a convex lenticular lens, and a cross-sectional view taken along the line AA. FIG. 1 (B) is a perspective view of a lenticular lens sheet in which a convex lenticular lens is imprinted with fine grained rugged shapes and BB.
It is a sectional view taken along the line.

As shown in FIG. 1, the lenticular lens sheet of the present invention comprises a base lenticular lens sheet 11 and a fine concavo-convex shape 12 formed thereon. Further, the fine uneven shape does not have a particular range regarding the size, but as a pattern that can be formed on a film sheet, it is usually 1 μm to 200 μm.
It is considered to be a range having a periodicity of m. This is because it corresponds to the maximum value and the minimum value of the manufacturable range of the sheet. Also,
It must be smaller than the pitch of the substrate lenticular lens.

Such a lenticular lens sheet is formed by pressing a plastic film for molding, which has fine irregularities formed by an ionizing radiation curable resin in advance on the surface of the film, against the surface of the lenticular lens sheet during molding of the lenticular lens sheet. It can be formed by peeling the shaped plastic film after the molding resin has cooled. Examples of the ionizing radiation curable resin for forming the fine concavo-convex shape include resins such as epoxy, polyester, acryl and urethane acrylate. The shaping plastic film may be one that has good permeability to ionizing radiation such as electron beams (EB) and ultraviolet rays (UV) and good releasability from the resin for the substrate lenticular lens sheet. In general, polyethylene terephthalate,
Examples include nylon and polyolefin. These films may be subjected to a release treatment in order to enhance the releasability of the resin. In the formation of the base lenticular lens sheet, it is possible to use a dispersion of a diffusing agent in a thermoplastic resin having good light transmittance such as acrylic resin.

FIG. 2 is a diagram showing a step of providing fine unevenness on the film surface by the method for producing a lenticular lens sheet of the present invention. In FIG. 2, the mold roll 21, which serves as the center, is provided with a fine concavo-convex shape 22. When the fine concavo-convex shape is made to be convex on the lenticular lens surface of the base sheet, it is necessary to engrave the concave fine concavo-convex shape on the mold roll, and when it is made concave, the mold roll is It is necessary to engrave a convex fine concavo-convex shape.

Below the die roll 21, a nozzle coating device or a discharge nozzle 23 of an ordinary coater is provided to supply a liquid resin. The resin is suitably an uncured ionizing radiation curable resin, preferably an ultraviolet curable resin. This is because the curable resin is less likely to be deformed by heating and pressurizing in the subsequent process.
The ionizing radiation-curable resin may be supplied on the mold roll or the film, but it is necessary to supply the resin so that air bubbles do not mix in the recessed portions of the mold roll.

On the left and right of the mold roll, pressure rolls 24 and 2 for feeding the supply film along the peripheral surface of the roll.
5 are provided. Further, on the side opposite to the discharge nozzle 23, an ultraviolet irradiation unit 2 for curing the ultraviolet curable resin is provided.
6 are provided. The film 27 supplied from the lower part of the mold roll comes into contact with the ultraviolet curable resin 28 filled between the pressing roll 24 and the mold roll 21 in the fine irregularities engraved on the mold roll. The resin wets the film surface, but at this stage, it is in a state where it has not yet been cured. When the film is pressed and passes through the ultraviolet irradiation section 26 as the roll rotates, the resin is polymerized and hardened and fixed on the film surface. The plastic film on which the fine irregularities have been formed in this way is peeled off from the mold roll 21 at the position of the pressing roll 25 and wound up.

On the surface of the die roll, fine irregularities 22 are formed.
Are formed. Such an engraving roll can be manufactured by a known grinding technique, etching technique, or electroforming technique. As described above, it is difficult to form the fine concavo-convex shape on the mold roll, which means that it is difficult to form the fine concavo-convex shape by overlapping the shape of the lenticular lens or the like. It is a commonly practiced technique to form a die roll alone.

Next, a step of forming a lenticular lens sheet using the plastic film having the fine irregularities will be described. FIG. 3 is a view showing a cross section of a shaped plastic film having a fine concavo-convex shape used in the manufacturing method of the present invention. Fine concavo-convex shapes 29 made of an ionizing radiation curable resin are formed on the surface of the plastic film 27. FIG. 4 is a diagram showing a step of forming a lenticular lens sheet by using the plastic film on which the fine concavo-convex shape is formed simultaneously with the lenticular lens molding by the manufacturing method of the present invention.
(A) shows a single-sided imprinting process, and (B) shows a double-sided imprinting process.
In FIG. 4 (A), reference numeral 31 is a die roll on which the uneven shape of the lenticular lens is formed. Normally, 0.
The shape of the lenticular lens is engraved in parallel with the circumferential direction at a pitch of about 1 to 0.2 mm. A pressing roll 32 also serves as cooling. A plastic film 36 having fine irregularities formed thereon is supplied to the die roll 31 along the peripheral surface, and a molten acrylic resin is supplied from the T die 33 to the fine irregularity forming surface of the film and the pressing roll 32.
It is supplied so that it may be dripped during. At this time, the pressing roll 32 side may be indented in a shape different from that of 31, and may be formed on both sides.

The resin supplied from the T die is the mold roll 3
The resin is temporarily laminated integrally with the shape-imparting plastic film 36 having the shape of 1 and the fine concavo-convex shape formed therein, and at the same time, the resin is cooled and solidified. The shape-imparted plastic film that is temporarily integrated is peeled from the lenticular lens sheet when the lenticular lens sheet separates from the mold roll 31. Normally, the adhesiveness between the UV curable resin and the thermoplastic resin is weak, so
The substrate lenticular lens sheet can be easily separated from the shaped plastic film.

In FIG. 4B, a plastic film 36 having fine irregularities formed on both the mold roll 31 and the pressing roll 32 is supplied along the peripheral surfaces of both rolls. Therefore, when the molten acrylic resin supplied from the T die 33 is cooled, it becomes a lenticular lens sheet having fine irregularities formed on both surfaces thereof.

FIG. 5 shows a mold roll (A) having a fine lenticular lens shape and a mold for a base lenticular lens when a fine lenticular lens shape is formed in parallel on a base lenticular lens sheet by the manufacturing method of the present invention. It is a figure which shows the part of a roll (B). In the case of FIG. 5, the mold roll (A) is engraved with twelve fine lenticular lenses for one pitch of the mold roll (B). It does not necessarily correspond to one pitch of the roll (B). This is because the one-pitch planar linear distance of the die roll (B) and the distance along the curved surface do not match, and experimental trial and error is required to provide a number of minute pitches that exactly match one pitch. is necessary. In addition, accurate parallel line alignment is also required. The shape of the lens formed on the lens sheet is not limited to the lenticular lens, but a V wrench,
The shape can be a polygonal pyramid or a mat.

If the shape-imparting plastic film used is too thick with respect to the uneven pitch of the mold of the substrate lenticular lens, the uneven shape will not be faithfully reproduced. Therefore, it is also preferable that the film has an appropriate film thickness and that it expands and contracts to some extent when heated.

[0021]

【Example】

(Production of Molding Film with Fine Concavo-Convex Shape) A groove for a linear lenticular lens having a semicircular cross section with a pitch of 20 μm and a height of 20 μm was indented and prepared on the surface of a mold roll. A semicircular groove was formed on the entire surface of the die roll surface, orthogonal to the roll axis. The mold roll is set in the apparatus of FIG. 2, the ionizing radiation curable resin 28 is supplied between the mold roll 21 and the plastic film 27, and while the film is wound around the roll and conveyed, the light source 26 Due to ultraviolet rays (160 W / cm)
Was irradiated to cure the ionizing radiation curable resin on the surface. The film used was a polyethylene terephthalate film (PET film) having a thickness of 25 μm, and the ionizing radiation curable resin was a urethane acrylate-based ultraviolet curable resin (“XD-80 manufactured by Dainichi Seika Kogyo Co., Ltd.”).
8 ") was used. On the surface of the PET film separated from the engraving roll, a semicircular linear fine lenticular lens shape having a pitch of 20 μm and a height of 20 μm was formed parallel to and parallel to the film flow direction.

(Molding of Acrylic Resin and Molding with Shaped Plastic Film) Next, the lenticular lens sheet was extrusion molded using the apparatus shown in FIG. At that time, it was pressed between the mold roll 31 and the thermoplastic resin so that the fine lenticular lens shape of the shaped PET film on which the fine lenticular lens shape was formed was on the thermoplastic resin side. The slit width of the die was adjusted so that the lenticular lens sheet had a predetermined thickness (0.9 mm), and extrusion molding was performed at a predetermined speed (2.5 m / min). Also, the die roll has a pitch of 800
A shape having an elliptical cross section with a depth of 500 μm and a depth of 500 μm continuously engraved in the circumferential direction was used.

(Peeling of Molding Film) When the base lenticular lens sheet made of a molded acrylic resin is transferred from the mold roll 31 to the cooling roll 34 side, the mold P is formed.
Peel the ET film from the substrate sheet. A lenticular lens sheet having a fine lenticular lens shape formed on an acrylic resin lenticular lens surface on the surface of the substrate sheet as shown in FIG. 1A was obtained.

Since the lenticular lens sheet manufactured in this manner has fine irregularities formed on the surface, it has the effect that the light incident from the back surface is diffused in multiple directions. FIG. 6 is a diagram showing a locus when light rays are incident on a base lenticular lens sheet formed in parallel with a lenticular lens shape of a base lens sheet according to the present invention, in which a fine lenticular lens shape is shaped. As shown in FIG. 6, the situation is shown in which the light rays are diffused in multiple directions. FIG. 7 is a view showing a fine lenticular lens shape according to the present invention on an observer side when a light ray incident from the back side of the lenticular lens sheet formed in parallel with the lenticular lens shape of the base lens sheet passes through the sheet. It is a figure which shows a luminance distribution. The characteristics shown in this figure do not necessarily indicate the ideal characteristics of a lenticular lens because the imprinting pitch is coarse (large), but it is not possible to further reduce the imprinting pitch or to make the shape of the minute lenticular lens smaller. It is significant that research will provide the effect of replacing conventional diffusing agents.

[0025]

The surface of each lenticular lens element of the lenticular lens sheet of the present invention has fine irregularities. Therefore, scattered light from various positions of the lenticular lens element reaches the observer, and the side gain can be improved. Further, in the past, a lens sheet having a fine concavo-convex surface, which was considered impossible due to the limitations of the mold manufacturing technology, was easily manufactured by molding at the time of molding using a patterning film having a fine concavo-convex shape. Therefore, the same diffusion effect can be obtained without reducing the light transmittance due to the use of the diffusing agent. It should be noted that the present invention is not limited to the lenticular lens shape, and may be V without departing from the technical idea of the present invention.
It is self-evident that linear shapes such as wrenches, pyramids, and mats are included.

[Brief description of drawings]

FIG. 1 is a perspective view and a sectional view of a lenticular lens sheet according to the present invention.

FIG. 2 is a diagram showing a step of providing fine unevenness on the film surface by the manufacturing method of the present invention.

FIG. 3 is a view showing a cross section of a shaped plastic film having a fine uneven shape used in the manufacturing method of the present invention.

FIG. 4 is a diagram showing a step of forming a lenticular lens sheet by using the plastic film on which fine irregularities are formed at the same time as forming the lenticular lens by the manufacturing method of the present invention. (A) shows a single-sided imprinting process, and (B) shows a double-sided imprinting process.

FIG. 5 shows a mold roll (A) having a fine lenticular lens shape and a mold roll (B) having a base lenticular lens when a fine lenticular lens shape is formed in parallel on a base lenticular lens sheet by the manufacturing method of the present invention. It is a figure which shows the part of.

FIG. 6 is a diagram showing a locus when a light ray is incident on a base lenticular lens sheet formed in parallel with a lenticular lens shape of a base lens sheet according to the present invention, in which a fine lenticular lens shape is formed.

FIG. 7 is a view showing a fine lenticular lens shape according to the present invention on the observer side when a light ray incident from the back side of the lenticular lens sheet formed in parallel with the lenticular lens shape of the base lens sheet passes through the sheet. It is a figure which shows a luminance distribution.

[Explanation of symbols]

 11 Base Lenticular Lens Sheet 12 Fine Concavo-convex Shape 21 Mold Roll 22 Fine Concavo-convex Shape 23 Discharge Nozzle 24, 25 Pressing Roll 26 UV Irradiation Part 27 Film 28 UV Curable Resin 29 Fine Concavo-convex Shape 31 Mold Roll 32 Pressing Roll 33 T Die 34 Molding Resin 35 Lenticular Lens Sheet Molded by Molding 36 Molding Film Formed with Fine Concavo-Convex Shape

Claims (4)

[Claims] 1. A lenticular lens sheet used for a transmissive screen, which comprises a lens plate in which a plurality of lenticular lens elements each having a lenticular lens shape are arranged in parallel in a plane on a light entrance surface, and A lenticular lens sheet, characterized in that fine concavo-convex shapes are formed on the surface of each lens element. 2. The lenticular lens sheet according to claim 1, wherein the fine concavo-convex shape is a lenticular lens shape provided in parallel with the base lenticular lens. 3. The lenticular lens sheet according to claim 1, wherein the fine concavo-convex shape is a grain shape, a conical shape, or a pyramidal shape provided on the base lenticular lens. 4. (a) A transparent or semitransparent plastic film which is pressed and conveyed along the peripheral surface of a mold roll in which fine irregularities are engraved on the surface of the mold roll, and a recess of the mold roll. The space formed by the engraved part is filled with an ionizing radiation curable resin at the time when the plastic film comes into contact with the mold roll, and the ionizing radiation is irradiated from the back surface of the plastic film being conveyed to cure the ionizing radiation curable resin. Between the step of curing the resin to produce a shaped plastic film in which fine irregularities are formed, and (b) a thermoplastic resin between two mold rolls in which the shape of the lenticular lens is recessed on at least one side. When the lenticular lens sheet is extruded and extruded, the fine concavo-convex shape of the shaped plastic film is made so that it is in contact with the thermoplastic resin. A step of supplying along the mold roll to bring the thermoplastic resin into contact with the thermoplastic resin under pressure and a step of (c) cooling and solidifying the thermoplastic resin and then peeling off the shaped plastic film are sequentially performed. A method of manufacturing a lenticular lens sheet, which comprises: