JPS59167237A - Manufacture of zoom-lens barrel - Google Patents

Abstract

PURPOSE:To obtain a light-weight lens supporter with a variable power portion having excellent dimensional accuracy by using a light-weight plastic material having excellent mass productivity and also using an eccentric bush in molds for injection molding. CONSTITUTION:Eccentric bushes 10 and 11 are each inserted into and fixed to a fixed mold 8 and a movable mold 9. A pin 11a to form the slide hole 2 of a supporter 5 is inserted into and fixed to the eccentric bush 11 and is insertable into the hole 10a of the bush 10 under the condition that the molds are closed. The pin 11a is also detachable to the bush 11. A core 9a, along with the molds 8 and 9, makes up a cavity to form the supporter 5, and the core 9a is fitted into the movable mold 9. After the completion of one-time molding, the biased a mount of dimensions, accompanying the deformation of the supporter 5, is measured, and the pine hole 11b of the eccentric bush is adjusted to obtain a given dimension.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a method for manufacturing a lens barrel for a zoom lens, and particularly to a mold for molding a plastic member suitable for a support member of a variable power system.

[Prior art]

Support members for variator and compensator lenses used in the variable power portion of high-power zoom lenses such as video cameras are manufactured by die-casting aluminum.

These support members are finished by post-processing by machining in order to ensure dimensional accuracy. Therefore, the support member is expensive and, since aluminum is used, it is also heavy. On the other hand, low-magnification 8 mm cameras and the like have loose tolerances for dimensional accuracy, so cheap and lightweight plastic support members are used. However, for high-precision zoom lenses used for high magnification, video cameras, or photography, there is no suitable means to ensure the dimensional accuracy necessary to maintain zero optical characteristics, and currently plastic support members are not used. do not have. The main reason why dimensional accuracy of the plastic support member cannot be achieved is as follows.

To ensure dimensional accuracy of plastic molded products.

The goal is to reduce molding shrinkage and reduce molding variations. In order to achieve this objective, additive β materials such as glass fibers are blended into the plastic base material, but although this greatly improves the above objective, it does not reach the high precision range required for optical properties. This is due to internal stress in the gate area.

This is because the orientation of the additives has a subtle influence. Particularly after injection molding, warping and deformation occur on the surface, which is the main cause of poor precision. In particular, the sliding hole of the variable power part support member according to the present invention cannot achieve dimensional accuracy due to the above reasons, which is a major reason why plastic is not used.

[Purpose of the invention]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a lens for a variable power section, a lens support member, and a method for manufacturing the same, which are inexpensive, lightweight, and have excellent dimensional accuracy, eliminating the above-mentioned drawbacks.

[Summary of the invention]

In order to obtain the above-mentioned support member, the present invention uses a plastic material that is excellent in mass production and can be made lightweight, and also uses an eccentric bushing in an injection mold to prevent dimensional deviations caused by warping or deformation. This is corrected by the tsushi.

[Embodiments of the invention]

It is a variable power unit of a zoom lens according to the present invention.

The supporting members of the variator and compensator and the manufacturing method thereof will be explained.

FIG. 1 is a plan view of a support member of a plastic variator or compensator for a zoom lens according to the present invention, and FIG.
The figure is a sectional view taken along the line AA in FIG. FIG. 3 is a sectional view of a main part of an injection mold showing the manufacturing apparatus of the present invention. Figure 4 is the 6th
FIG. 3 is a plan view of the eccentric bushing attached to the figure manufacturing device. FIG. 5 is a sectional view taken along the line BB in FIG. 4.

First, the support member obtained by the manufacturing apparatus of the present invention will be explained. In FIGS. 1 and 2, 1 is a lens ball holding portion, 2 is a sliding hole, and 3 is a sliding groove 4 which is a cam follower. The cam follower 4 is a pin embedded in the support member 5. The functions of each part of the support member 5 having the above structure will be explained. 1iC has a lens ball inserted and fixed in a predetermined position, and has the functions of zoom lens variable power and aberration correction. 2, it is possible to move the support member 5 along with the zooming operation. A guide rod (not shown) is inserted and the support member reciprocates over the guide rod. 3 has the function of holding other guide rods and restricting the rotational movement of the support member 5 about the optical axis during zooming. 4 is inserted into a cam groove (not shown) that defines a predetermined movement amount for zooming, and moves guided by the cam groove during zooming, thereby regulating the movement of the support member 5 in the optical axis direction. .

Reference numeral 6 indicates an optical axis, and reference numeral 7 indicates a central axis of the sliding hole 2.

The support member 5 having the above structure moves on the guide rod by approximately several tens of millimeters as the zoom lens changes magnification, and during this time the optical axis 6 of the support member and the optical axis of the entire zoom lens are always aligned. must be done.

In order to achieve this objective, for example, the dimension 1 between the central axis 7 of the sliding hole 2 and the optical axis 6, and the parallelism between the optical axis 6 and the central axis 7 must be ensured with high precision. However, as described above, the dimensions are not uniquely determined due to the orientation of the additives and the internal stress of the gate portion. For this reason, the third
If the manufacturing apparatus of the present invention shown in the figure is used, this dimensional correction can be easily and accurately performed, and a highly accurate support member can be obtained.

Next, the manufacturing apparatus of the present invention is shown in FIGS. 3 and 4.

I will explain this using Figure 5.

8 is a fixed type, and 9 is a movable type. Eccentric bushes 10.degree. 11 are inserted and fixed into the fixed mold 8 and the movable mold 9, respectively, and the eccentric bushes are each removable. A pin 11α forming the sliding hole 2 of the support member 5 is inserted and fixed into the eccentric bushing 11, and can be inserted into the hole 10α of the eccentric bushing 10 when the M6 pattern is closed. Further, the pin 11α can be attached to and detached from the eccentric bushing 11. 9α is a fixed type 8. It constitutes a space (cavity) that forms the support member 5 together with the movable mold 9, and is a piece fitted into the movable mold 9.

In the manufacturing apparatus having the above configuration, if molten resin is injected through the gate 12, the fixed mold 8° movable mold 9. Enter piece 9
The space formed by a and the like is filled with molten resin. Next, when the fixed mold 8 and the movable mold 9 are separated from the parting 13, the supporting member 5 is released from the surface formed on the fixed mold 8 and the eccentric pusher 10, and then a known ejecting pin (not shown) is released. If the ejection is performed using the movable mold 9. It is released from the input piece 9α and the pin 11α and can be taken out from the mold.

To explain the eccentric pusher of the present invention in more detail, FIG. 4 shows a plan view of the eccentric pusher 11 removed from the movable mold 9, and the eccentric bush 11 can be easily attached to and removed from the movable mold 9. For this reason, the eccentric push-piece can be machined as a single item, and specifically, the hole 11A into which the pin 11α is installed can be machined to be eccentric from the center of the bush as desired, as shown in Figure 4. . The same applies to the eccentric pusher 10 inserted into the fixed mold 8.

Therefore, after the first molding is performed, by measuring the amount of dimensional deviation due to the deformation of the support member and adding the amount of deviation to the pin hole 11b of the eccentric pusher, the predetermined size can be obtained.

According to this dimension, it is possible to prepare a required number of fixed and movable eccentric bushings and repeatedly attach and mold them until a predetermined dimension is obtained. Conventionally, the pin 11α was directly attached to the movable mold 9 without using an eccentric bush. For this reason, there is no way to correct dimensional deviations, and
This was a major reason why plastic supporting members could not be applied.

Another feature of the present invention is that it is not only applicable to dimensional deviations of the sliding hole 2, but also can correct inclination errors between the optical axis 6 and the central axis 7 of the sliding hole 2 due to deformation.

A previously anticipated amount of inclination can be achieved by providing the pin hole 11b of the eccentric bushing 11LL with an inclination. As described above, the manufacturing apparatus according to the present invention can reliably secure predetermined dimensions using a simple method, and it has become possible to obtain a plastic support member that is low in cost and lightweight. Note that the embodiment of this embodiment also includes a case where only one of the fixed type and the movable type is used as an eccentric bush, and the pin attached to the eccentric bush is used as a pusher.

Furthermore, in the embodiment, an example of a cylindrical bushing was shown as shown in FIG. Needless to say, the shape does not matter. 6th
The figure shows an example of another bushing having a prismatic shape, and the reference numerals are the same as in FIG. 4.

〔Effect of the invention〕

According to the present invention, since a replacement eccentric bushing is applied in the mold, the sliding hole, which had been a problem in terms of dimensional accuracy of the variable power support member, can be molded with high precision. Therefore, the plastic support member can be applied to a zoom lens, which is effective in reducing the weight and cost of the zoom lens.

[Brief explanation of drawings]

FIG. 1 is a plan view of a plastic support member for a zoom lens, FIG. 2 is a sectional view taken along the line A-A in FIG. 1, FIG. 3 is a sectional view of a manufacturing device according to an embodiment of the present invention, and FIG. 4 5 is a plan view of the eccentric pusher, FIG. 5 is a sectional view taken along the line B-B in FIG. 4, and FIG.
The figure is a plan view of another eccentric pusher. 2...Sliding hole, 5...Supporting member, 8...Fixed type, 9...Movable type, 10.11...Eccentric bushing, 11α...Pin 11A...Pin hole. Representative Patent Attorney Akio Takahashi Figure 1 Figure 2 Closed Figure 3 (2) O 6

Claims (1)

[Claims] In an injection mold for manufacturing a support member for a variator and a compensator lens of a zoom lens zooming unit, a sliding hole is provided for inserting a guide rod for moving the support member onto the optical axis during zooming. A tossable zoom lens mirror characterized in that it is shaped by an eccentric bushing detachably attached to a fixed type and a movable type, and a pin detachably attached to an eccentric bushing of either the fixed type or the movable type. How to manufacture tubes.