JPH09117921A - Mold for cast molding of resin lens for glasses - Google Patents

Abstract

PROBLEM TO BE SOLVED: To keep the sectional form of a gasket constant to a mold used for the precision molding of the concave surface of a plastic lens for glasses to an aspheric surface such as a hyperboloidal surface, elliposoidal surface or the like and/or a toroidal surface. SOLUTION: At the peripheral part of a mold 1, 2 for molding a concave surface, a surface A, against which a gasket 3 is abutted, is so constituted as to lie in the same plane and, by changing the height (h) of the surface B, the height H of a portion serving as the roll of the spacer of the gasket 3 is made to be constant. Further, by providing at least two adjoining surfaces to the surface A, the airtightness between the gasket 3 and the mold 1, 2 is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the shape of a mold for cast molding.

[0002]

2. Description of the Related Art Among spectacle lenses made of plastic, lenses having a dioptric power in a common range are manufactured by a casting polymerization method, but a prescription lens manufactured based on a spectacle prescription, particularly a lens having a high power and a spherical surface. Almost all lenses having both diopter and astigmatism are manufactured by preliminarily manufacturing semi-finished lenses by polishing based on a spectacle prescription. In the polishing work from this semi-finished lens, rather than polishing both sides based on the eyeglass prescription, one side is a molding surface that does not require polishing processing, and the other surface is molded into an unprocessed surface. It is efficient to polish only the unprocessed surface based on the recipe.
Eyeglass lenses generally have a meniscus shape, the concave surface is molded by a mold with an arbitrary simple curvature, and is usually molded as a spherical unprocessed surface, and the convex surface has a predetermined shape and curvature. It is molded with a mold that has been highly accurately polished, and is formed on the spherical surface corresponding to the mold surface that does not require polishing, and once the customer's spectacle prescription is determined, it is not based on that prescription. By polishing the concave surface of the processing, the prescription lens desired by the customer is completed and provided.

As described above, in the case of a semi-finished lens, in order to complete this as a prescription lens, it is necessary to polish the concave surface side, and an aspherical shape such as a hyperboloidal surface or an elliptic surface or a complicated surface is required. Polishing an astigmatism lens that constitutes a toroidal surface requires many kinds of complicated jigs and tools, and requires extremely advanced technology. Therefore, there is a drawback that it takes a lot of processing time to obtain a lens with high processing accuracy.

In general, among plastic single-focus lenses, prescription lenses completed by polishing semi-finished lenses are mainly used for special powers other than the range normally produced by lens manufacturers. Is used for
The sphere and the astigmatism are mainly composed of lenses having a considerably high intensity. Therefore, the lens completed by polishing the concave surface as described above has a considerably thick peripheral portion, which is not preferable in appearance.

Further, both the spherical degree and the astigmatism have a spherical shape, and a lens manufactured by polishing has a drawback that spherical aberration occurs, and because of the intensity number as described above, this spherical aberration The problem is bigger. In particular, plastic lenses with a shape that is technically extremely difficult to mass-produce due to the polishing process do not have to manufacture the required complicated shape each time, but rather the shape is complicated and polished. The surface that is difficult to process and requires advanced technology is used as a molding surface corresponding to the mold surface that does not require polishing, by using a mold that is formed with high precision with an arbitrary shape and curvature. This is more desirable in terms of the difficulty of polishing, the production yield and the processing time.

In order to overcome such a problem, the inventors have proposed that the convex surface is a spherical unprocessed surface and the concave surface is an aspherical surface such as a hyperboloidal surface or an elliptic surface, or the aspherical surface is a toroidal surface. An attempt was made to obtain a semi-finished lens molded on a molded lens surface that does not require polishing, which has a special surface shape to which the above is added, and the results thereof are shown in Utility Model Registration Application No. 1-38235. In the practical stage, as shown in FIG. 3, the height H'is changed so as to follow the curved surface at the peripheral portion of the mold in order to improve the sealing performance of the mold 7 and the gasket 8 for molding the concave side of the lens. Moreover, the gasket was manufactured in conformity with the curved surface E. Since the gasket is manufactured by injection molding, a large number of molds are required to match changes in the aspherical surface and / or toroidal surface because a mold is required, resulting in enormous cost and increased lens cost. I am Further, as shown in FIG. 3, the gasket 8 and the mold 7 have only two contact surfaces, that is, the E portion and the F portion, and there is an increasing demand for improving the adhesiveness.

[0007]

The problems to be solved are to reduce the types of gasket molding dies and to improve the adhesion between the mold and the gasket.

[0008]

The present invention is a mold in a casting mold, wherein the precisely polished surface constitutes an aspherical surface such as a hyperboloidal surface or an elliptic surface and / or a toroidal surface. At least one surface of the contact portion with the gasket is formed in the same plane.

Further, the surface of the abutting portion of the gasket and the mold is constituted by a surface formed by the same plane and at least two other surfaces adjacent to the surface to improve the sealing performance.

[0010]

1 is a sectional view of a mold showing an embodiment of the present invention. 1 and 2 are molds, 3 is a gasket, and 4 is a resin injected through the injection port 9. The circled portion shown by the broken line in FIG. 1 is enlarged and shown in FIG. By setting the surface A at the peripheral edge of the mold 1 on the same plane over the entire circumference, and by setting the surfaces B and C adjacent to the surface A so as to be orthogonal to the surface A and lightly press against the gasket 3. Good sealing performance. Here, the height h of the surface B changes following the aspherical surface and / or the toroidal surface of the precisely polished surface 5 of the mold 1. That is, the point that is greatly different from the conventional mold is that the mold is provided with two surfaces A and B. Further, the surfaces A and B do not necessarily have to be orthogonal to each other and may be two adjacent surfaces.

Since the molding surface 6 of the mold 2 is a surface which is polished into a spherical convex surface based on the optometry, it may be a spherical surface having a predetermined radius of curvature. Therefore, the surface D of the peripheral portion in contact with the gasket 3 is the same. The height H, which lies in the plane and thus serves as a spacer for the gasket 3, is constant.

With the above-mentioned structure, only one mold is required for injection-molding the gasket 3. However, considering that it is possible to deal with extreme astigmatism, the number of molds may be 2 to 3.
It can be used practically by preparing different types.

[0013]

As described above, when the mold of the present invention is used, even if the precision-polished surface is composed of an aspherical surface such as a hyperboloidal surface, an elliptic surface, and / or a toroidal surface, it can be injected with one kind of gasket. Molding is possible, and there is only one type of mold for injection molding the gasket, so it is extremely economical. In addition, the sealing property with the gasket is improved, and it is possible to prevent bubble generation and early mold release. The present invention can also be used when the objective surface side of the lens is an aspherical surface.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a relationship between a mold and a gasket.

FIG. 2 is a partially enlarged view of FIG. 1;

FIG. 3 is a cross-sectional view showing a relationship between a conventional mold and a gasket.

[Explanation of symbols]

 1, 2 Mold 3 Gasket 4 Resin 5 Precision polishing surface 6 Molding surface 7 Mold 8 Gasket

Claims (2)

[Claims] 1. A mold for a casting mold of a resin lens for spectacles comprising a mold and a gasket, wherein a precisely ground surface constitutes an aspherical surface such as a hyperboloidal surface or an elliptic surface and / or a toroidal surface. A cast molding mold for a resin lens for spectacles, characterized in that at least one of the surfaces of the portion of the mold that comes into contact with the gasket is formed in the same plane. 2. The resin lens for spectacles according to claim 1, wherein the surface of the abutting portion is composed of a surface formed of the same plane and at least two other surfaces adjacent to the surface. Cast molding.