JPH08281820A - Resin molding material for objective lens, and the lens - Google Patents

Abstract

PURPOSE: To obtain a resin molding material for an objective lens which can provided the lens made of resin having stable optical characteristics in which no gate mark remains in the effective aperture of the lens after molding. CONSTITUTION: A molding material 9 for press molding an objective lens satisfies A>B, where A is the width of the resin molding material in which the shape is substantially spherical and B is the height of the material, and has a gate mark 10 for injection molding on the side of the material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin molding material for an objective lens, which is a component of an optical pickup for recording or reproducing information by projecting a light spot on an optical disk, and the objective lens.

[0002]

2. Description of the Related Art In recent years, objective lenses have been CD players, C
Along with the miniaturization of recording / reproducing devices using an optical pickup such as a D-ROM, the thickness and weight of the recording / reproducing device have been reduced. An example of the above-mentioned conventional molding material for an objective lens will be described below with reference to the drawings. FIG. 8 is a side view showing the shape of the objective lens 21 used in the optical pickup after molding. As shown in FIG. 6, a press-molding material for manufacturing such an objective lens 21 is formed by polishing the entire surface. Such a spherical glass polishing ball material 22 (hereinafter referred to as glass ball glass material 22) is used.

FIG. 7 is a sectional view of an objective lens molding die 23 used for press molding of an objective lens. An upper mold 24 for molding the first surface of the objective lens and a second surface of the objective lens are shown. It is composed of a lower mold 25 to be molded and a cylindrical barrel mold 26 that forms the thickness and side surface of the objective lens. Since the glass ball glass material 22 is obtained by polishing the entire surface, as shown in FIG. 7, the glass ball glass material 22 is arranged in the objective lens molding die 23 without specifying the directionality and is pressed in this state. Processing machine (not shown)
The objective lens 21 can be formed by press molding using an objective lens molding die by arranging in the above and performing heat pressing.

[0004]

However, when the weight of the objective lens 21 is further reduced as described above, a resin material having a smaller specific gravity than a glass material is adopted as the material of the objective lens 21. . When a ball glass material is injection-molded with a resin material instead of the glass ball glass material 22 as shown in FIG. 9, a resin-molded spherical ball glass material 31 (hereinafter referred to as resin-molded ball glass material 31) is used for injection molding. The gate mark 32 remains.

As a countermeasure against this, when the ball glass material 31 is placed in the objective lens molding die 23 as shown in FIG. 10, the position of the gate mark 32 of the ball glass material 31 is set in the lateral direction 33 of the resin molded ball glass material 31 (after molding). Must be arranged so as to be the side surface portion 37 of the objective lens 36) and press-molded. If this kind of consideration is not taken,
As shown in FIG. 3, the gate mark 32 remains in the effective diameter 38 (broken line) of the objective lens 36, and the optical characteristics of the objective lens 36 deteriorate.

Further, even if such consideration is taken, the objective lens forming die 23 is actually produced by vibration of equipment such as a forming machine, a die, or a conveyor during production.
In the inside, the ball glass material 31 is displaced due to its own rotation or the like, and the gate mark 32 wraps around the effective surface of the objective lens mold, and the gate mark 3 is formed in the effective diameter 38 of the objective lens 36 after molding.
2 remains, which causes a problem that the optical characteristics of the objective lens 36 deteriorate.

In view of the above problems of the prior art, the present invention provides an optical resin molding material for an objective lens capable of stably molding a resin press-molded objective lens, and an optical system in which no gate mark is left in the effective diameter of the objective lens after molding. An objective lens made of resin with stable characteristics is provided.

[0008]

In order to solve the above problems, a resin molding material for an objective lens according to the present invention is a substantially spherical resin molding material used for molding a resin press-molded objective lens. When the shape of the substantially spherical resin material is the width A of the resin molding material and the height (thickness) B of the resin molding material, the relationship of A> B is satisfied, and the width direction of the resin molding material is satisfied. An injection molding gate position is provided on the side surface portion.

[0009]

According to the present invention, with the above-mentioned structure, even if the objective lens is press-molded by using the resin molding material for injection molding in which the gate mark remains, the gate mark does not remain within the effective diameter of the objective lens, and the optical characteristic It is possible to provide a stable objective lens without deterioration.

[0010]

EXAMPLES An example of an objective lens resin molding material of the present invention and an objective lens press-molded using the molding material will be described in detail with reference to FIGS. 1A and 1B show a resin molding material for an objective lens in one embodiment of the present invention. FIG. 1A is a plan view of the molding material, and FIG. 1B is a side view of the molding material. In FIG. 1, 9 is a resin molding material for an objective lens and 10 is a gate mark for injection molding. A is the width of the resin molding material for the objective lens, and B is the height (thickness) of the resin molding material for the objective lens. Then, the resin molding material 9 for the objective lens
Has a substantially spherical shape, and the dimensions of width A and height B satisfy the relation of A> B, so that the gate mark 10 at the time of injection molding remains on the side surface portion of the resin molding material 9 for the objective lens. It is made by an injection molding machine in which the gate of the injection molding machine is arranged.

FIG. 2 is a sectional view of an objective lens molding die 1 used for press molding of the objective lens of the present invention, in which a spherical surface portion of the die for molding the first surface (spherical surface or aspherical surface) of the objective lens. A lower mold 3 having a mold spherical surface 12 for molding the second surface (spherical surface or aspherical surface) of the objective lens, and a cylindrical barrel mold 4 forming the thickness and side surface of the objective lens. To be done. 2 shows a state in which the objective lens resin molding material 9 is heated and press-molded by the objective lens molding die 1.

FIG. 3 shows a side view of the objective lens obtained by hot press molding the resin molding material for the objective lens of the present invention. In FIG. 3, 13 is an objective lens, 14 is a side surface portion of the objective lens, and 15 is a gate mark. The operation of the resin molding material for an objective lens configured as described above will be described below.

As shown in FIG. 1, the resin molding material 9 for an objective lens of the present invention has a substantially spherical shape and has a width A and a height B of A.
Satisfies the relation of> B, and the gate mark 10 at the time of injection molding
Is provided on the side surface of the objective lens resin molding material 9. As a result, the resin molding material 9 for the objective lens is self-standing with the gate mark 10 held to the side surface portion to some extent, and the resin molding material 9 for the objective lens rotates due to the dimensional relationship of the shape being substantially spherical and A> B. Therefore, the position of the gate mark 10 is not oriented upward or downward, for example.

Utilizing this, as shown in FIG. 2, a resin molding material 9 for the objective lens is arranged in the objective lens molding die 1 so that the gate traces 10 are in the horizontal direction, and hot press molding is performed. 3, the resin molding material 9 for the objective lens causes a rotational displacement due to the vibration of equipment such as a mold and a conveyor, and the gate mark 10 does not come into contact with the spherical surface portions 11 and 12 of the objective lens molding die 11 and are not molded as shown in FIG. As shown, the gate mark 15 remains on the side surface outer peripheral portion 14 of the objective lens 13,
Gate trace 15 without remaining within the effective diameter 8 (broken line) of 3
This makes it possible to form a stable objective lens without the deterioration of optical characteristics due to the influence of.

FIGS. 4A and 4B are side views showing another embodiment of the resin molding material for an objective lens of the present invention. In FIG. 4, 16 and 17 are resin molding materials for an objective lens, and 15 is a gate mark.
It is shaped so that it is easy to cut a flat gate on the circumference around the position. FIG. 5 shows a side view of another embodiment of the resin molding material for an objective lens of the present invention. In FIG. 5, 18 is an elliptic resin molding material for an objective lens, and 15 is a mark of a gate. And
Each of the objective lens resin molding materials 16, 17 and 18 has a substantially spherical shape having spherical surfaces on both sides in the height (thickness) direction as shown in the figure, and the dimensions of width A and height B are A> B. The relationship is satisfied, and the gate mark 10 at the time of injection molding is made by the injection molding machine in which the gate of the injection molding machine is arranged so as to remain on the side surface of the resin molding material for the objective lens.

As a result, the resin molding materials 16 and 17 for the objective lens have a substantially spherical shape and have a dimensional relationship of A> B.
Also in 18 as in the case of the resin molding material 9 for the objective lens, the gate mark 10 is self-standing in a posture in which it is held to the side surface to some extent, and the resin molding material 9 for the objective lens is rotated so that the position of the gate mark 10 is, for example, upward or downward. Never localized to. Therefore, after the heat molding by the press molding machine, the gate mark 15 remains on the side surface outer peripheral portion 14 of the objective lens 13,
Without remaining within the effective diameter 8 (broken line) of the objective lens 13,
This makes it possible to form a stable objective lens without deterioration of optical characteristics due to the influence of the gate mark 15.

[0017]

INDUSTRIAL APPLICABILITY As described above, the present invention provides an injection molding resin molding material for press molding an objective lens,
The shape of the resin molding material is almost spherical, the width of the resin molding material is larger than its height, and the injection molding gate mark is provided on the side surface of the resin molding material. Even if the objective lens is press-molded by using it, the gate mark does not remain within the effective diameter of the objective lens, and it is possible to provide a stable objective lens without deterioration of optical characteristics.

[Brief description of drawings]

1A is a plan view showing a resin molding material for an objective lens according to an embodiment of the present invention, and FIG. 1B is a side view showing a resin molding material for an objective lens according to an embodiment of the present invention.

FIG. 2 is a partial cross-sectional side view showing a state in which the resin molding material for an objective lens of the present invention is press-molded by a molding die for an objective lens.

FIG. 3 is a side view showing an objective lens obtained by press molding the resin molding material for an objective lens of the present invention.

FIG. 4A is a side view showing another embodiment of the resin molding material for an objective lens of the present invention. FIG. 4B is a side view showing another embodiment of the resin molding material for an objective lens of the present invention.

FIG. 5 is a side view showing another embodiment of the resin molding material for an objective lens of the present invention.

FIG. 6 is a side view showing a conventional spherical glass polishing ball material for molding an objective lens.

FIG. 7 is a cross-sectional view of a conventional objective lens molding die.

FIG. 8 is a side view of a conventional objective lens.

FIG. 9 is a side view showing a conventional resin molded ball glass material for molding an objective lens.

FIG. 10 is a cross-sectional view of a conventional molding die for a resin molding objective lens.

FIG. 11 is a side view of a conventional resin objective lens.

[Explanation of symbols]

 1 Objective lens molding die 8 Effective diameter of objective lens 9 Resin molding material for objective lens 10 Gate trace

Claims (2)

[Claims] 1. A substantially spherical resin molding material used for molding a resin press-molded objective lens, wherein the shape of the substantially spherical resin material is a width of the resin molding material: A, and a height of the resin molding material. S: When B, satisfy the relationship of A> B,
Further, a resin molding material for an objective lens, characterized in that an injection molding gate mark is provided on a side surface portion in the width direction of the resin molding material. 2. An objective lens formed by molding the resin molding material according to claim 1, wherein the injection molding gate mark is located on the outer side surface portion of the curved surface forming the lens effective diameter after molding. The objective lens characterized by the above.