JPH02193101A - Production of mold for molding lens sheet - Google Patents

Abstract

PURPOSE:To efficiently form the mold for molding lenses which can deal with even the extremely large-sized seamless lens sheet by bringing a lens molding surface and an inverted mold surface into tight contact with each other, then injecting a plastic liquid for packing into the small spacing and solidifying the liquid to integrate the surfaces. CONSTITUTION:End-plates 2 are provided around a matrix 1 and a resin liquid 3 which is the raw material for the plastic mold is injected therein and is solidified to form the plastic mold 3. Such plastic molds 3, 3 are disposed to face each other in a butted state apart the small spacing and a backing mold 4 having the mold surface 4A inverted from the lens molding surface 3A is positioned on the rear surface of the opposed parts and the lens molding surface 3A and the inverted mold surface are brought into tight contact with each other, thereafter, the plastic liquid 3' for packing is injected into the small spacing. The forming mold which can form the extremely large-sized seamless lens sheet is efficiently formed in this way.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention c. Fresnel lenses and lenticular lenses used in video projection television screens;
Alternatively, the present invention relates to a method of manufacturing a mold for producing a particularly large lens sheet such as a Fresnel lens for condensing light.

(Prior art) When manufacturing lens sheets such as Fresnel lenses and lenticular lenses, injection molding of synthetic resin is used when the size is relatively small and mass production is required. When manufacturing a relatively large lens sheet F for optical use, it is common to contact a resin plate with a flat lens mold, heat and press the resin plate, and transfer the lens surface.

However, this method has the disadvantage that it takes a long time for heating and cooling, making it difficult to increase productivity.

For this reason, a method has recently been proposed in which an ultraviolet curable resin liquid is interposed between the lens mold and the transparent resin substrate and cured by irradiation with ultraviolet rays (Japanese Patent Laid-Open No. 61-177215
(see publication).

By the way, among these manufacturing methods, the method of manufacturing Lens Sheet F using ultraviolet curable resin makes it possible to obtain a large lens sheet with relatively simple equipment, but there are restrictions on the size of the mold. In order to obtain an ultra-large lens V-), it was necessary to join the previously created Fresne L/L/lens.

(Problem to be solved by the invention) However, when multiple lens sheets are joined together, the seams become noticeable and deteriorate the appearance and performance. is required.

In view of this situation, the present invention aims to efficiently manufacture a molding die that can be used to manufacture even extremely large lens sheets using various manufacturing methods.

(Another Means to Solve the Problem) In other words, the gist of the present invention is to make mutual plastic molds each having a lens molding surface on one side face each other in abutting manner with a small distance therebetween, and to on the bottom -
After positioning a mold with a mold surface opposite to the lens molding surface and bringing the lens molding surface and the reverse mold surface into close contact, inject plastic liquid for filling at small intervals to assimilate and integrate. A method of manufacturing a mold for molding a lens sheet is provided.

A more detailed explanation will be given below with reference to the drawings.

Figure 1 shows the matrix (1), which has the same shape as the unit of the lens sheet that will be finally manufactured.
made of metal or plastic. In the case of a plastic matrix (1), the lens portion may be formed by thermal transfer together with a mold having an opposite shape. therefore,
It is also possible to use the lens sheet as a product as a matrix.

Figure 2 shows the process of manufacturing a plastic mold (3), in which a weir (2) is erected around the mother mold (1) and resin liquid (3'), which is the raw material for the plastic mold, is injected into it. and solidify. Examples of the resin used in such a method include silicone resin, urethane resin, and Evokin resin.

Note that the production of the plastic mold (3) is not limited to this method, and may also be performed using a hot press or the like.

Figure 3 shows the lens molding surface (3A
) with a plastic mold (3) shown.

FIG. 4 shows a state in which the plastic molds (3) are butted against each other and integrated. That is, the plastic molds (3) and (3) are placed facing each other at a small distance (the width of two lenses in the figure), and the lower surfaces of the facing portions are coated with the lens molding surface (5A). After positioning the holding mold (4) with the reverse mold surface (4A) and bringing the lens molding surface (3A) and the reverse mold surface into close contact, inject the plastic liquid for filling (3 pieces) at small intervals. The plastic liquid (3) is preferably the same as the plastic mold (3), but a different type may be used as long as it has good adhesion.

In addition, as a method for bringing the reverse mold surface (4A) of the holding mold (4) into close contact with the lens molding surface (3A) of the plastic mold (3), for example, as shown in FIG. 6, weights ( It is best to press down from above and below by placing 5) on it. In addition, to improve adhesion, use a plastic mold (3).
Alternatively, it is effective to make one of the molds (4) from a flexible material.

FIG. 5 shows the molding die obtained by the above method, which is large and excellent in that the abutting portions are also integrated.

By using the mold thus obtained, a correspondingly large lens sheet can be manufactured, and a method using an ultraviolet curable resin is particularly suitable for this manufacturing method. That is, an epoxy acrylate or urethane acrylate resin liquid is cast onto the surface of the mold obtained by the above method, an acrylic resin plate or a polycarbonate resin plate is placed from above to serve as a transparent substrate, and ultraviolet rays are irradiated through the transparent substrate. This is a method to obtain a lens sheet by irradiating and curing the material.

Although the illustrated embodiment describes a mold for manufacturing a lenticular lens sheet, the present invention can also manufacture a mold for molding a Fresnel lens sheet or a fly's eye sheet.

(Example) First, a mold was prepared in which a metal plate having a length of 2 m and a width of 1 m had a large number of parallel gutter-shaped surfaces extending in the length direction at a pitch of 11 III. And on this mold, the thickness is 3m and the length is 2m.
, an acrylic resin plate with a width of 1 m was placed on it, and hot pressing was carried out under the conditions of a temperature of 180° C. and a pressure of 50 kg and 7 cm 2 to obtain a matrix and a pad as shown in FIGS. 1 and 4.

Next, create a weir around the matrix obtained above as shown in Figure 2,
Here, silicone resin (IKE130 manufactured by Shin-Etsu Silicon Co., Ltd.
] RTV j) and harden it to a thickness of about 5III
Six plastic molds of I++ were made.

The three-sided plastic mold thus obtained was placed in the fourth
As shown in the figure, they are placed face to face with an interval of 3f1 between them, and below these two small spaces, two supporting molds are placed, and a weight is placed above them as shown in Fig. 6. The same silicone resin used above was injected into the space and cured.

When molded after curing, it was possible to obtain a plastic mold with a length of 2 m and a width of approximately 6 m, with almost no seams.

Using this mold, a lenticular lens sheet was manufactured by interposing an ultraviolet curable resin liquid between the sheet and the transparent substrate. The transparent substrate at this time is 3cm thick and 2x3
A transparent acrylic resin plate (“Acrylite”nook (not containing an ultraviolet absorber) manufactured by Mitsubishi Rayon Co., Ltd.) was used, and the following ultraviolet curable resins were used.

・Mitsubishi Rayon urethane acrylate “UK-60”
38J 60 Weight Section/Hydroxyethyl acrylate "Acrieste" vHO manufactured by Mitsubishi Rayon Co., Ltd.
40 weight benzophenone 3 weight 1
(For the sum of the above two) Next, from this transparent substrate side, ultraviolet rays are irradiated with three SOW high-pressure mercury lamps at an irradiation distance of 15 m and a moving speed of s m of 7 minutes, and the lens portion is integrally formed by curing. did.

The obtained lenticular lens had a good appearance with no seams.

(Effects of the Invention) Since the present invention has the configuration as described in detail above, it has the advantage that it is possible to efficiently manufacture a seamless lens mold that can be used even for extremely large molds.

[Brief explanation of the drawing]

1 to 5 are sectional views showing steps of a manufacturing method according to an embodiment of the present invention, and FIG. 6 is a partial perspective view similarly showing one step of the present invention. (1)...matrix, (2)...cough, (3)
...Plastic molds, (three...trees (for making plastic molds))
8th effect, (4)... guess type

Claims (1)

[Claims] Mutual plastic molds each having a lens molding surface on one side are placed in abutting relationship with a small distance therebetween, and a holding mold having a mold surface opposite to the lens molding surface is placed on the lower surface of the facing portion. A method for manufacturing a mold for molding a lens sheet, characterized in that the lens molding surface and the reverse mold surface are brought into close contact with each other, and then a plastic liquid for filling is injected at small intervals to solidify and integrate.