JP2000218634A - Apparatus for molding planar lens - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an optically uniform molding with a simple constitution by a little number of steps by providing a drivable valve made of polyethylene or ethylene tetrafluoride at each of a filling port and a discharge port. SOLUTION: A treated base thin plate 2 is set in an insert dowel 1. Then, a filling valve 30 made of polyethylene or ethylene tetrafluoride is moved down. A main valve 51 provided on the way of piping from a pumping tank 50 is opened, and a resin is filled in the tank. To completely fill the resin in the tank, a discharge valve 31 made of polyethylene or ethylene tetrafluoride of a discharge port 15 is moved down to discharge the resin. After a predetermined amount of the resin is discharged, the valve 30 and the valve 31 are raised to complete filling. Thereafter, an ultraviolet ray is emitted from an ultraviolet ray emitting unit 13 to cure the resin of a cavity 3. After a mold is opened, an ejector pin 12 is raised, and a molding is released from the mold. Thus, a uniform lens surface is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for a flat lens made of a thin substrate and an ultraviolet curable resin.

[0002]

2. Description of the Related Art Many molding methods using an ultraviolet curable resin have been proposed as methods for molding Fresnel lenses.

In Japanese Patent Publication No. 6-88276, in FIGS. 3 and 5 of the publication, a resin injection port for injecting an ultraviolet curable resin is provided on one side of a lower mold, and a tapered filling port is provided. Provided. Further, a discharge port for overflowing the resin is provided on the other side of the lower mold.

[0004]

The above-mentioned prior art method of manufacturing a Fresnel lens using an ultraviolet curable resin has the following problems.

[0005] Both the tapered filling port and the discharging port provided at the resin injection port are divided into a cured portion, an uncured portion, and a portion in a gel state in between when the resin is cured.
The hardened portion has a tapered shape. Therefore, in order to use this molded product as a lens, it is necessary to remove the tapered filling port, which requires extra man-hours. In addition, since gel-like resin exists around the uncured part, the gel-like resin is mixed at the filling port at the next filling, and the resin to be filled later and the cured resin after curing , The lens surface may be uneven.

An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a flat lens forming apparatus capable of obtaining an optically uniform formed product with a simple structure and a small number of steps. is there.

[0007]

Means for Solving the Problems In order to solve the above-mentioned object, the construction of the method of forming a flat lens according to the present invention comprises the steps of forming a base plate which transmits ultraviolet rays and a mold having a cavity surface engraved into a predetermined shape. In a method of molding a desired molded product by filling a cavity formed by the cavity surface with an ultraviolet curable resin and irradiating the resin with ultraviolet light from the substrate thin plate side to cure the resin. Equipped with a drivable valve made of polyethylene or tetrafluoroethylene at the filling port for filling the resin and the discharge port for discharging the surplus resin, the valve is lowered when filling the resin, and the valve is raised except when filling. To do.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a flat lens according to the present invention, a molding method thereof, and a manufacturing apparatus will be described in detail.

FIG. 1 is a sectional view showing an entire manufacturing apparatus used for carrying out the method of forming a flat lens according to the present invention. FIG. 2 is a sectional view showing the structure of a flat lens formed by the forming apparatus of the present invention. FIG. 3 is a sectional view showing a filling port for filling the ultraviolet curable resin and a discharge port for discharging surplus resin according to the present invention. FIG. 4 is a cross-sectional view of the molded article of the present invention which is cured with the valve of the filling port and the discharge port for discharging surplus resin raised.
FIG. 5 is a cross-sectional view of a molded article of the present invention which is cured with the valve of the filling port and the discharge port for discharging excess resin being lowered.

First, the configuration of the flat lens of the present invention will be described. As shown in FIG.
Is made of an acrylic styrene copolymer plate as the base sheet 2 that transmits ultraviolet light, and the base sheet and an acrylic or epoxy-based ultraviolet curable resin 150 are integrally polymerized.

Next, an outline of this manufacturing apparatus is shown in FIGS.
This will be described using 3.

This manufacturing apparatus comprises: a base plate 2 that transmits ultraviolet light; and a cavity surface 1 of a mold insert 1 in which a cavity surface 1a is engraved into a predetermined shape (a shape opposite to a flat lens surface).
The ultraviolet curable resin is conveyed from the pressure feed tank 50 via the main valve 51 into the cavity 3 formed by the above-mentioned process a. After filling, the filling valve 30 is raised, and then the resin is irradiated with ultraviolet rays from the base thin plate 2 side to cure the resin, whereby the hardened lens portion and the base thin plate are cured. 2 is formed by integrally polymerizing and adhering a desired molded product, and the molded product is released by raising the ejector pin 12 to obtain a flat lens.
The upper die 7 has the transparent plate 4 and a holding member 7a for holding the transparent plate 4 on the side opposite to the cavity.

Around the mold, one or more resin outlets 15 are provided with a discharge valve 31. The upper plate 7 has the transparent plate 4 attached thereto. The transparent plate 4 is made of glass (quartz,
Alternatively, it may be a blue plate glass or an acrylic resin plate). Above the transparent plate 4 of the upper die 7, an ultraviolet irradiation device 13 is attached. The opening and closing operations of the upper die and the lower die are performed by a pneumatic or hydraulic cylinder 52.

An embodiment of the method for molding an ultraviolet-curable resin according to the present invention using the manufacturing apparatus having the above-described configuration will be described.

First, a mixture of 98 parts by weight of benzyl methacrylate and 2 parts by weight of a photopolymerization initiator is spray-coated on a thin substrate and left at room temperature (25 ° C.) for 90 seconds to 120 seconds. And set it on the molding machine. At this time, it has been found that if the standing time is short, the surface of the base thin plate is not activated, and the adhesiveness to the ultraviolet curable resin is deteriorated later. Also, experiments have revealed that if the standing time is longer than the above-mentioned time, the surface of the base sheet is dried, and a cracked pattern is formed on the joint surface when the sheet is integrated with the ultraviolet curable resin later. ing.

The substrate thin plate 2 thus treated is set on the mold insert 1. Thereafter, the filling valve 30 made of polyethylene or ethylene tetrafluoride is lowered, and the main valve 51 provided in the middle of the pipe from the pressure feed tank 50 is lowered.
And release the resin. In order to completely fill, the discharge valve 31 made of polyethylene or tetrafluoroethylene at the discharge port 15 is lowered and discharged, and after a certain amount is discharged, the filling valve 30 and the discharge valve 31 are raised to complete the filling. . After that, the resin in the cavity 3 is cured by irradiating the resin with ultraviolet light by the ultraviolet irradiation device 13. After the mold is opened, the ejector pins 12 are raised to release the mold.

As shown in FIG. 4, the molded article thus obtained was cured with the filling port and the valve of the discharge port for discharging the surplus resin being raised, so that the molded article was placed near the filling port and the discharge port. There is no protruding UV curable resin. In addition, since the filling port is completely cured, a uniform lens surface 101 is obtained without mixing the gel resin at the time of the next filling.

However, as shown in FIG. 5, when the filling port and the valve of the discharge port for discharging the surplus resin are cured in a lowered state, the protrusions near the filling port and the discharge port as in the prior art are formed. UV curable resin is produced. In addition, since a gel-like resin is present around the uncured portion, the gel-like resin is mixed during the next filling, and the degree of curing after curing is different from that of the resin to be filled later. Therefore, unevenness 98 occurs on the lens surface.

The charging valve 30 and the discharging valve 31
Is made of polyethylene or tetrafluoroethylene which does not adhere to a general ultraviolet curable resin, so that when the valve moves up and down, it does not stick to the ultraviolet curable resin and does not become difficult to move.

In the embodiment of the present invention, a transparent acrylic styrene copolymer plate is used as the substrate thin plate.
Styrene, acrylic, polycarbonate, polymethylpentene and the like may be used.

[0021]

As described above, according to the present invention, a drivable valve made of polyethylene or tetrafluoroethylene is provided at the filling port for filling the ultraviolet curable resin and the discharge port for discharging the surplus resin. Therefore, when filling the resin, the valve is lowered, and when not filling, the valve is raised to prevent the uncured resin from being exposed.Therefore, the step of removing the cured resin at the filling port can be omitted, and the lens surface has unevenness. It is possible to provide a flat lens molding method that does not occur, and a manufacturing apparatus directly used in the method.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing the entire flat lens forming apparatus according to the present invention.

FIG. 2 is a sectional view showing the structure of a flat lens formed by the forming apparatus of the present invention.

FIGS. 3A and 3B are cross-sectional views showing a filling port for filling the ultraviolet curable resin of the present invention and a discharge port for discharging excess resin.

FIG. 4 is a perspective view of a molded product cured according to the present invention with a filling port and a valve of a discharge port for discharging surplus resin being raised.

FIG. 5 is a perspective view of a molded product cured according to the present invention in a state where a valve of a filling port and a discharge port for discharging surplus resin is lowered.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Die insertion piece, 1a ... Cavity surface, 2 ... Thin substrate, 3
... cavity, 4 ... transparent plate material, 7 ... upper die, 8 ... lower die, 9
... Filling port, 10 ... Valve, 12 ... Release pin, 13 ... UV irradiation device, 14 ... Resin filling port, 15 ... Resin discharge port, 2
5 ... Pressing device, 30 ... Filling valve, 31 ... Discharge valve, 52 ... Pneumatic or hydraulic cylinder.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Naotake Ebinuma 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Inside Hitachi, Ltd. F-term in Ronic Devices Co., Ltd. (reference) 4F204 AA44 AG02 AH74 AJ03 AK03 EA03 EB01 EB13 EF01 EF23 EF27 EF48 EK25 4F213 AA13E AA21 AA21E AA39 AA44 AB01 AH74 WA02 WA53 WA56 WA58 WF01 WF01 WB01 WF01

Claims (1)

[Claims] An ultraviolet curable resin is filled into a cavity formed by a base plate that transmits ultraviolet light and the cavity surface of a mold having a cavity surface engraved in a predetermined shape, and the resin is irradiated with ultraviolet light from the base plate side. In the method of molding a desired flat lens by irradiating the resin and irradiating the resin, a polyethylene or polyethylene tetrafluoride ethylene is provided in a filling port for filling the ultraviolet curable resin and a discharge port for discharging excess resin. An apparatus for forming a flat lens, comprising a drivable valve.