JP2558121B2 - Manufacturing method of Fresnel lens - Google Patents

Description

The present invention relates to a method for manufacturing a Fresnel lens used for a large rear screen or the like.

[Conventional technology]

Conventionally, as a method of manufacturing this type of Fresnel lens,
The pressing method, casting method, etc. were known.

The former pressing method has poor productivity because it is manufactured by heating, pressurizing and cooling cycles.

The latter casting method has a problem that it takes a long manufacturing time because a monomer is poured into a mold to polymerize, and a large number of molds are required, resulting in an increase in manufacturing cost.

In order to solve such a problem, a UV polymerization method has been proposed in which an ultraviolet (UV) curable resin is poured between a mold and a transparent supporting substrate and the resin is cured by irradiating with ultraviolet rays to cure the resin. There is.

In this method, an ultraviolet-curable resin is applied to a Fresnel lens mold, an ultraviolet-transparent transparent substrate is laminated on the resin under pressure, and then the resin is irradiated with ultraviolet rays to be cured. .

[Problems to be solved by the invention]

This UV polymerization method has a problem that productivity is poor because bubbles easily enter between the Fresnel lens mold and the transparent substrate and the manufacturing work needs to be performed in a vacuum atmosphere.

An object of the present invention is to provide a manufacturing method capable of inexpensively manufacturing a Fresnel lens having good optical characteristics without causing bubbles between the Fresnel lens mold and the transparent substrate even in a vacuum atmosphere. .

[Means for solving problems]

The present invention is an improvement of the method for manufacturing a Fresnel lens using a so-called UV polymerization method.

FIG. 1 is a block diagram for explaining a method of manufacturing a Fresnel lens according to the present invention.

The first resin applying step 101 is a step of applying an ultraviolet or electron beam curable first resin to the entire surface of the Fresnel lens mold. In this step, the surface of the Fresnel lens mold is wetted with an ultraviolet (UV) or electron beam (EB) curable resin to facilitate defoaming in the next step, and at the same time, it functions to obtain surface physical properties. An acrylate resin can be preferably used as the first resin. To perform this step,
It can be applied by a screen printing method, a roll coating method, a curtain coating method, an offset method or the like.

The second resin application step 102 is a step of forming a resin pool of a second resin curable by ultraviolet rays or electron beams on the first resin in the substantially central portion of the Fresnel lens mold. In this step, air bubbles entering the transparent substrate are expelled at the time of pressing described later, and at the same time, the first coating applied to the entire surface of the transparent substrate.
Functions to improve the adhesion to the resin. This resin pool is molded by dropping it in the approximate center of the mold with a despacer or the like.

As the first and second resins, ultraviolet or electron beam curable resins can be used, and examples thereof include acryloyl group-containing polymerizable compounds such as urethane acrylate, epoxy acrylate, polyester acrylate, polyether acrylate, and melamine acrylate. Oligomer,
Examples thereof include a monomer and a polymerizable oligomer having a polymerizable vinyl group such as acrylic acid, acrylamide, acrylonitrile, and styrene, or a monomer or the like alone or in combination.

Regarding the physical properties of the resin, the mold transferability, the defoaming property, the wettability with respect to the mold, and the surface curability are important for the first resin, and the second resin has the adhesiveness with the transparent substrate. , Liquidity is important.

The first resin and the second resin are selected in consideration of the above points, but it is required that at least the refractive indexes of both are substantially equal. This is because the interface where the first resin and the second resin are laminated is not necessarily flat, and if the refractive indices of the two resins are significantly different, uniform light cannot be obtained.

If this relationship is satisfied, the first resin and the second resin may be made of the same material or different materials.

In the case of different resins, combinations having substantially the same refractive index may be used in consideration of physical properties.
As the resin, a urethane acrylate resin having excellent mold reproducibility and surface curability can be used, and as the second resin, an epoxy acrylate resin having good adhesion to a base material can be used.

It should be noted that using different resins has the advantage that one resin can be used for substrate adhesion and the other resin can be used for imparting physical properties.

When the same material is used, the resin temperature in the process of processing the first resin and the second resin is changed, an additive (defoaming agent, leveling agent, etc.) is added, or the first resin is added. By changing the compounding ratio of the monomer and oligomer of the resin and the second resin, the wettability to the mold,
Flowability and viscosity can be adjusted appropriately.

Further, both or one of the first resin and the second resin may contain a light diffusing substance. In that case, it is preferable to mix a diffusing agent in the first resin. By incorporating a diffusing agent, it is possible to prevent shrinkage and to impart light diffusing property. As the diffusing agent, glass, silica, alumina, crosslinked beads and the like can be used.

The substrate laminating step 103 is a step of laminating a transparent substrate transparent to ultraviolet rays or electron beams on the second resin. As this transparent substrate, PVC, acrylic, polycarbonate,
Substrates molded from styrene, TPX, etc. can be used, and can be subjected to a primer treatment in order to improve adhesion.

The surface plate laminating step 104 is a step of laminating a surface plate having an ultraviolet or electron beam irradiation surface on the transparent plate. The surface plate used in this step is to perform UV or EB curing during pressurization, it relaxes the strain after decompression, and functions to prevent so-called tunneling where bubbles enter from around the transparent substrate. To do.

This surface plate can serve as a light guide path for a light source provided on the side surface.

For this surface plate, a plate made of glass, acrylic, or the like is used, and as a light guide path for the irradiation surface, there are a method of using prisms to utilize total reflection, a method of forming a reflection layer on a slope, and the like.

The pressure pressing step 105 is a step of pressing the surface plate.

The resin curing step 106 is a step of irradiating each of the resins with an ultraviolet ray or an electron beam through the surface plate to cure the resin.

The depressurizing and releasing step 107 is a step of depressurizing the pressure of the surface plate and releasing.

〔Example〕

Hereinafter, the present invention will be further described with reference to the accompanying drawings and the like.

FIG. 2 is a process diagram showing an embodiment of the method for manufacturing a Fresnel lens according to the present invention, and FIG. 3 is a diagram showing a surface plate used in the embodiment method.

In FIG. 2, 1 is a Fresnel lens mold, 2 is a first resin, 3 is a second resin, 4 is a transparent substrate, 5 is a surface plate, and 6 is a UV light source.

First, as shown in FIG. 2 (a), a urethane acrylate UV-curing resin as a first resin 2 was applied to a Fresnel lens mold 1 having a vertical width of 30 cm by a roll coating method at 30 g /
cm ^{2 was} applied.

Next, as shown in FIG. 2 (b), an epoxy acrylate-based UV curable resin was dropped as a second resin 3 onto the Fresnel lens mold 1 at approximately the center thereof using a 6 g despacer.

As shown in FIG. 2 (c), as the transparent substrate 4, a UV transparent acrylic plate having a thickness of 3.0 mm and having a vinyl chloride / vinyl acetate copolymer-based primer applied at ² g / cm ² was laminated. At this time, air bubbles entering between the Fresnel lens mold 1 and the transparent substrate 4 are extruded at the portion indicated by A in the figure.

Further, as shown in FIG. 2 (d), pressing was performed from above the transparent substrate 4 with a pressing machine having a surface plate 5 attached thereto at a pressure of 1 kg / cm ² . As shown in FIG. 3, this surface plate 5 is made by adhering an acrylic plate 51 having a prism-shaped aluminum vapor deposition surface 51a of vertical 300 mm and width 400 mm and an inverse prism-shaped acrylic plate 52 facing each other. is there.

At this time, 1k which is the UV light source 6 attached to the end surface of the surface plate 5
Irradiation was performed for 30 seconds using a W mercury lamp to cure the first resin 2 and the second resin 3.

Finally, as shown in FIG. 2 (e), the Fresnel lens mold 1 was depressurized and released to obtain a Fresnel lens in which air bubbles were not mixed.

〔The invention's effect〕

As described in detail above, according to the present invention, since the UV or EB curable resin applied to the central portion of the Fresnel lens mold expels air bubbles, it is not necessary to use a vacuum system at the time of manufacturing, and it can be manufactured by an inexpensive manufacturing facility. it can.

In addition, since the resin is cured during the pressurization, tunneling is small and the plate thickness can be kept uniform.

Furthermore, since the manufacturing cycle is short, the required number of Fresnel lens molds is small, and efficient manufacturing is possible.

Furthermore, since the cured resin can be used in two types, one for adhering to the substrate and one for imparting physical properties, it is possible to improve the overall physical properties.

[Brief description of drawings]

FIG. 1 is a block diagram for explaining a method of manufacturing a Fresnel lens according to the present invention. FIG. 2 is a process drawing showing an embodiment of the manufacturing method of the Fresnel lens according to the present invention. FIG. 3 is a view showing a surface plate used in the method of the embodiment. 1 ... Fresnel lens mold 2 ... 1st resin, 3 ... 2nd resin 4 ... Transparent substrate, 5 ... Surface plate 6 ... UV light source

Claims (4)

(57) [Claims] 1. A first resin applying step of applying a first resin curable to ultraviolet rays or an electron beam to the entire surface of a Fresnel lens mold, and the first resin on a substantially central portion of the Fresnel lens mold. A second resin applying step of forming a resin reservoir of a second resin curable with ultraviolet rays or electron beams on the second resin, and a substrate laminating step of laminating a transparent substrate transparent with ultraviolet rays or an electron beam on the second resin, A surface plate laminating step of laminating a surface plate having an ultraviolet or electron beam irradiation surface on the transparent plate, a pressure pressing step of pressurizing the surface plate, and an ultraviolet ray or an electron beam to each resin through the surface plate. A method of manufacturing a Fresnel lens, which comprises a resin curing step of irradiating the resin with light and curing, and a depressurizing and releasing step of depressurizing and releasing the pressure of the surface plate. 2. The method of manufacturing a Fresnel lens according to claim 1, wherein the surface plate serves as a light guide path for a light source provided on a side surface. 3. The method for manufacturing a Fresnel lens according to claim 1, wherein the first resin and the second resin are different resins. 4. The method of manufacturing a Fresnel lens according to claim 1, wherein both or one of the first resin and the second resin contains a light diffusing substance.