JPH06293527A - Molding die for aspherical lens - Google Patents

Abstract

PURPOSE:To improve the life of a molding die for an aspherical lens to be used for various optical instruments, and to obtain a lens of good quality produced by using this die. CONSTITUTION:A pair of molding dies 1, 2 are assembled with the axes coinsident and provided with a drum mold so that the dies can be slided in the vertical direction. The space formed by this pair of dies 1, 2 and the drum mold 3 is filled with a glass raw material. The whole dies are heated to press mold the glass. In this process, the lower molding die 2 has a second extra work surface F.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aspherical lens molding die for molding an aspherical lens used in optical equipment by a precision glass molding method, and an aspherical molded lens.

[0002]

2. Description of the Related Art In recent years, many molding methods have been tried to form optical lenses and are in a practical stage. In such a molding method, a molding die corresponding to the lens to be obtained and a glass material to be filled in the molding die may be manufactured and used for molding.

In general, the body of the forming die is manufactured so that the center axes of the lens functional surface (optical functional surface) processed into the upper die and the lower die coincide with each other.

At present, lenses are required to be smaller and lighter in the competition for smaller and lighter movies and the like.
Aspherical lenses compatible with inch CCDs have also appeared, and are becoming smaller and lighter.

Further, the aspherical lens corresponding to the 1/4 inch CCD is in the stage of practical use, and high magnification, small size and light weight are being advanced. Due to the higher magnification and smaller size, tolerances such as lens precision have become tighter than before.

Therefore, the center axes of the lens functional surfaces (optical functional surfaces) of the upper mold and the lower mold must be accurately aligned, so that if the upper mold and the lower mold are fitted together, the upper mold and the lower mold are fitted together. Mold,
The lower mold and the body mold hit.

[0007] Therefore, it is usually dimensioned and manufactured so as not to hit. However, the body mold and upper mold of the mold,
Little is known about the mating relationship with the lower mold.

FIG. 2A shows a state before molding using a conventional die, and FIG. 2B shows a state immediately after the lens is press-molded at a high temperature. , Lower mold 12, body mold 13, non-molded glass material 14, lens 1
4 '.

Aspherical shapes a and b are formed on the lens function surface of the upper mold 11 and the lens function surface of the lower mold 12, respectively. The body mold 13 is adapted to hold the upper mold 11 and the lower mold 12 so that their shafts are slidably aligned with each other.

In FIG. 2 (a), the upper mold 1 is moved in the direction of arrow f from the state before molding to obtain a press molding process, and the upper mold 1 is molded up to the position indicated by the gap c in FIG. 2 (b). , The lens function surfaces a and b of the lower mold 12 are transferred.

Even when the lens 14 'molded in this state is cooled, the central axis e of the lens 14' on the lens function surface b of the upper mold 11 and the lens function surface a of the lower mold 12 is the body mold 13 and the upper mold 1.
1 and the fitting precision d of the lower mold 12 makes it possible to obtain a lens having a desired precision.

That is, the dimension of the fitting accuracy d shown in FIGS. 3A and 3B is the accuracy (tolerance) required for the lens, and the larger the margin, the more stable the molding can be performed. .

Further, it is also an important condition that the upper die is vertically press-formed without inclination in the forming process and the accuracy of the concentricity of the body die 13, the upper die 11 and the lower die 12 is improved.

[0014]

However, in the above-mentioned conventional example, there is a limit to the pressure molding without tilting the upper mold during the molding process, and there are the following problems.

In recent years, lenses have been downsized and have high magnification, and since the accuracy and tolerance of the lens center axes of the upper lens function surface and the lower lens function surface are strict, it is attempted to improve the accuracy of the fitting portion. Then, the clearance between the body mold and the upper and lower molds is reduced, and the inner wall of the body mold and the side surface (outer peripheral part) of the upper mold contact in the process of press molding, and the metal particles are scraped each other and the metal powder is Since the metal powder drops onto the lens functional surface, enters between the lens functional surface and the glass material in the process of deformation, and the metal powder is transferred to the lens that has been press-molded, the desired lens appearance cannot be obtained.

Also, the shape of the lens function surface cannot be maintained, such as the lens function surface of the lower mold is scratched, and the life of the molding die is shortened.

In view of the above-mentioned conventional problems, it is an object of the present invention to surely obtain a desired lens appearance and a desired lens precision, extend the life of the molding die and improve the work efficiency.

[0018]

In order to solve the above-mentioned problems, the present invention provides a pair of molds including an upper mold and a lower mold having at least one optical functional surface having an aspherical shape, and a pair of molds. A first aspherical lens molding die having a barrel die that matches an axis and slides in a vertical direction, wherein a pair of molding die upper and lower die surfaces facing each other is an optical processing range.
And a second processed surface composed of a surplus processed surface.

[0019]

With the above construction, the processing surface of the molding die is composed of the first processing surface which is the optical processing range and the second processing surface which is the surplus processing surface, and slides between the upper mold and the body mold in the press molding process. Even when the side surface (outer peripheral portion) of the upper die and the inner wall of the body die contact with each other and the metal powder falls to the lower die due to the movement, the first die may be dropped onto the second surplus processed surface of the lower die. Set the dimensions of the surplus machined surface of 2.

When pressure molding is performed using this molding die, the lens to be molded is a desired lens.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic view showing the configuration of a lens and a molding die used for manufacturing the lens according to an embodiment of the present invention. Also in this embodiment, FIG. 1A shows a state before molding, and FIG. 2B shows a state immediately after the lens is press-molded at a high temperature. Aspherical shapes A and B are formed on the surfaces of the mold 1 and the lower mold 2 that face each other. The upper mold 1 and the lower mold 2 are slidably held by the body mold 3 with their axes aligned, as in the case of the above-mentioned conventional example.

Now, in this embodiment, the upper mold 1, the lower mold 2,
The relationship between the lens 4 ′ formed by the barrel mold 3, the first processed surface A (lens functional surface) of the lower mold 2 and the second surplus processed surface C will be described in detail.

In FIG. 1, an upper die 1, a lower die 2, a body die 3 and a fitting portion which have been processed to obtain a desired lens are indicated by C, and A and B are lenses for obtaining a desired lens 4 '. It is a functional surface, and the fitting portion of C is also a tolerance which determines the accuracy of the central axis D of the lens functional surface of A and B of the desired lens 4 '.

In molding, the upper die 1 moves in the direction of arrow g from the state of FIG. 1 (a), press molding is performed, and the deformation of the glass material 4 is started. Since the clearance of the fitting portion C is small during sliding in that process, the side surface portion of the upper die 1 and the inner wall of the body die 3 come into contact with each other, the metals are scraped, and the metal powder 5 falls onto the lower die 2. To do.

The smaller the clearance of the fitting portion C, the more frequently the metal powder falls. In the present invention, the first lens functional surface A is formed so that the metal powder 5 that has been molded and has fallen in FIG. 1B surely drops onto the second surplus processed surface E of the lower mold 2.
Set the dimensions by adding a step to the lens function surface A of the lower mold 2.
The aspherical lens 4'having a desired performance can be stably obtained by preventing the lens from falling.

Next, the relationship between the desired lens and the first optical processing range E and the second surplus processed surface F of the barrel die 3, the upper die 1 and the lower die 2 of the forming die according to this embodiment will be described.

Here, the desired lens volume is 149.745 mm.
³ , the center thickness of the lens is 3.2 mm, and the lens outer diameter is 9.4 m
When it is attempted to obtain an aspherical lens having an accuracy of 7.0 μm with respect to m and the central axis D, the volume of the molding die needs to be estimated to be larger than the volume of the desired lens. Therefore, for example, 172.277.
mm ³ Thus, the first optical processing range E of the lower mold is set to φ
12.6 mm, the second surplus processed surface F is provided with a step of 1.0 mm from the first optical processed surface E to temporarily be 2.7 mm, and the upper die 1,
The diameter G of the lower mold 2 is φ18.0 mm.

Since the tolerance of the center axis D of the desired lens 4'needs to be 7.0 μm or less, the diameter G'of the barrel die 3 '
Is φ18.007 mm or less, and the fitting part C is 3.5 μm
It becomes the following.

With the molding die thus constructed, pressure molding is started from the state shown in FIG. 1 (a), and even if the metal powder 5 falls onto the lower mold 2 in the sliding process, the second surplus processed surface F is formed. Since it falls, the molded aspherical lens can reliably obtain the desired lens in a stable manner.

[0030]

As described above in detail, according to the present invention, even if the clearance of the fitting portion is reduced, the metal powder during sliding falls on the second surplus machined surface of the lower die. The desired lens can be stably manufactured, and the molding efficiency can be improved.

Further, in the die as well, by providing the second surplus processed surface on the lower die, scratches on the lens functional surface are eliminated, and the life of the die can be extended.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a molded state of an aspherical lens according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a molding state of a conventional aspherical lens.

[Explanation of symbols]

 1 Upper mold 2 Lower mold 3 Body 4 Glass material

Claims (2)

[Claims] 1. A pair of molding dies having at least one optical function surface having an aspherical shape and consisting of an upper mold and a lower mold, and a barrel mold in which the axial centers of the pair of molding dies are aligned and slid vertically. A mold for an aspherical lens having: a first machined surface where the machined surfaces of the upper mold and the lower mold of the pair of molds facing each other are an optical machined area, and a second machined surface is a surplus machined area.
And an aspherical lens forming die. 2. A mold for an aspherical lens, wherein the upper and lower mold surfaces of the mold have a first machining surface having an optical machining range and a second machining surface having a surplus machining range. An aspherical molded lens characterized by being manufactured by.