JPH0371253B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a multilayer resin molded product that is formed as a lens barrel in an optical device, a video device, for example, a photographing device, or a lens barrel in an office machine. In particular, it relates to molded products such as lens barrel parts that enable electrical continuity.

[Background of the invention]

Taking the lens barrel of a camera as an example, conventionally, lens barrel products made of this type of plastic molding were only molded entirely from the same material, and multiple different materials were not layered in a sandwich-like structure. Not yet. For example, if it is PC-G (polycarbonate with glass fiber), this PC-G
The whole thing was molded in one piece. Furthermore, in the case of parts requiring electrical conductivity, the entire part was molded from a single material such as PC-G material, which is a combination of PC-G and carbon.

A more specific explanation will be given with reference to FIG. 5, which shows the lens barrel structure of these cameras.

As shown in FIG. 5, in a configuration including a focusing lens L ₁ , a variable magnification lens L ₂ , a correction lens L ₃ and an imaging lens L ₄ , the focusing lens L ₁ is held by a focusing lens holder 1, This focusing lens holder 1 is connected to a fixed lens barrel 2 by a helicoid coupling, and by rotating the focusing lens holder 1, the focusing lens _L1 is extended in the optical axis direction.

Further, the variable power lens L ₂ and the correction lens L ₃ are held by a lens holder 3 and a lens holder 4, respectively, and these lens holders 3 and 4 are guided by a guide bar 5 etc. using a well-known three-bar system. It is designed so that it can be moved in the direction of the optical axis.
The amount of movement of the variable magnification lens L ₂ and correction lens L ₃ in the optical axis direction is determined by cam lifts 6a and 6b provided on a cam ring 6 rotatably held in the fixed lens barrel 2.
controlled by. The cam ring 6 is adapted to rotate in response to the rotation of a zoom operation ring 7 fitted to the outer periphery of the fixed lens barrel 2. Further, the imaging lens L ₄ is held in the rear fixed barrel 14 by the imaging lens holder 13 via the diaphragm 12 and fixed with screws 15 .

The cam ring 6 is held between a front mask plate 8 and a rear mask plate 9 that hold three guide bars 5 inside the lens fixed barrel 2.

In the configuration described above, for example, the fixed lens barrel 2 requires sufficient mechanical strength because it is a basic component of the lens barrel, and the fitting diameter or overall length dimension etc. In order to be guaranteed under certain conditions, it is necessary to use materials with a coefficient of thermal expansion similar to that of metals. On the other hand, when an electrical shielding effect is required as a lens barrel member, a polycarbonate material containing carbon is mixed with carbon fiber, and the entire body is made of a molded plastic material with electrical conductivity. Needs to be shaped.

In this way, in order to mold a molded product from a single material while satisfying the required properties as a structural member or as a functional member such as conductivity, it is necessary to use polycarbonate with glass fiber or carbon material, for example. It is necessary to use a material that contains

However, when such a material containing glass fiber or carbon material is used, other problems may arise depending on the use of the molded product. For example, a threaded joint between a lens fixed lens barrel 2 and a focusing lens holder 1 that is joined with a helicoid screw,
Diameter fitting part with cam ring 6 or zoom operation ring 7
If glass fibers protrude from the surface of the lens fixed lens barrel 2 at the radial fitting portion, etc., this may cause problems such as scratches during sliding, or in severe cases, rattling of the fitting portion. Sometimes.

Therefore, several functions are required for such molded products, such as conductivity and good surface smoothness.
For example, Japanese Patent Publication No. 50-2864 proposes a method of achieving low friction by forming the molded article as a layered article made of different materials. This is a method generally referred to as the Sandermanch molding method, and specifically, a resin molded article having a multilayer structure is formed in the following manner.

First, the polycarbonate resin material that will form the surface of the lens barrel is injected into the cavity of the molding die, and then an electrically conductive material such as carbon (and optionally external glass fiber) is mixed in to form the core. By injecting the resin material, the surface layer (hereinafter referred to as the skin layer) becomes a smooth resin layer, and the core (hereinafter referred to as the core layer) becomes an electrically conductive (or even higher strength) resin layer to create a molded product. form.

By the way, if we consider in more detail the uses and usage of the multilayered resin molded products molded in this way, we find that, for example, conductivity has been imparted to the molded products for purposes such as electromagnetic shielding. Needless to say, it is necessary to ensure not only the conductivity of the molded product itself but also electrical continuity between the molded product and other members.

If it is possible to obtain a molded product that does not require special processing steps to ensure electrical continuity with other members, the effect in actual use will be extremely large.

[Purpose of the invention]

The present invention has been made from this point of view, and its purpose is to create a core layer having a conductive core layer and an insulating skin layer covering the surface thereof as a layered structure using the Sanderschitch molding method. A multilayer resin molded product configured so that electrical continuity between the core layer of the molded product and other components can be automatically obtained in conjunction with other operations. It is located in a place where products are provided.

[Summary of the invention]

The multilayer resin molded article of the present invention, made for this purpose, has a layered structure including a core layer made of a conductive material and a skin layer made of an insulating material covering the surface of the core layer. A first resin molded product formed to have a through hole in the part thereof, a core layer made of a conductive material, and a skin layer made of an insulating material covering the surface of the core layer as a layered structure. , is formed by said molding to have a pilot hole for screw threading exhibiting an inner surface covered with a skin layer, and the inner diameter dimension of the core layer covered by the skin layer in the pilot hole for screw threading is equal to that of the pilot hole. and a second resin molded product having a smaller diameter than the external dimension of the thread of the screw member to be screwed into the screw member, and the first and second resin molded products are provided in the through hole and the pilot hole of the screw member. The screw member and the core layer are connected by screwing, and the skin layer is torn to establish electrical continuity between the screw member and the core layer.

It goes without saying that the core layer in the above-mentioned molded article has electrical conductivity and may also be blended with, for example, glass fiber so as to impart high strength properties in addition to this.

As for the resin material constituting the above molded product, examples of the material for the core layer include glass fiber-containing polycarbonate, and examples of the material for the skin layer include natural polycarbonate.

[Embodiments of the invention]

Embodiments of the present invention will be described in detail below based on the drawings.

FIG. 1 shows the lens barrel structure of a camera constructed using a lens fixed lens barrel 2, etc. as a molded product of the present invention, and the parts are substantially the same as those of the conventional example shown in FIG. are shown with the same reference numerals.

A focusing lens holder 1 holds a focusing optical system _L1 , and is connected to a helicoid portion of a fixed lens barrel 2 with a helicoid screw. 6 is a zoom cam ring, and the V shown by 3 and 4 is held on the inner diameter part.
The movable ring, C movable ring, is moved in the optical axis direction according to the zoom cam lift, and 6d, 6e
The radial fitting portion shown in radially fits into the inner diameter portion of the lens fixed lens barrel 2, and is rotatably slidable. 7
is a zoom operation ring, which is rotatably radially fitted to the fixed lens barrel 2, and has an inner diameter side protrusion 7a;
By linking the notch 6c of the cam ring 6, the rotational movement of the zoom operation ring 7 is transmitted to the cam ring 6.

Reference numeral 18 denotes a relay barrel, which holds the afocal lens L ₅ on its inner diameter and is screwed to the lens fixed lens barrel 2 with screws 17 . Reference numeral 14 denotes a rear fixed barrel, which internally supports a lens holder 13 holding an imaging optical system L ₄ in its inner diameter portion, and is screwed to the relay barrel 18 with mounting screws 19 .

16 is a mount holder, and the rear end surface 16b
An image pickup element unit 21 can be attached to the rear lens barrel, and is connected to the rear lens barrel by a mounting screw 20.

In the above configuration, the lens barrel 2 of this example is
The multilayer resin molded product has a core layer 2a and a skin layer 2b, and the core layer 2a is made of polycarbonate containing 20% carbon fiber and 10% glass fiber.
The material b is molded using polycarbonate that does not contain the above-mentioned compounding material.

Further, as shown in an enlarged view in FIG. 2, the screw fixing part that is connected to the relay tube 18 by the screw 17 of the lens fixed lens barrel 2 is connected to the core by the self-tapping action when screwing the screw. A feature of the layer 2a is that it can ensure electrical continuity.

That is, at appropriate locations on the rear end surface portion 2c of the lens fixed lens barrel 2, pilot holes 2d for the screws for connection with the relay tube 18 are formed in advance during sander trench molding.

On the other hand, similarly to the fixed lens barrel 12, the relay tube 18 is formed using the sand-gerch molding method to have a core layer 18a made of a polycarbonate material mixed with carbon and glass fibers, and a skin layer 18b made of a natural polycarbonate material. Then, a plurality of blank holes 18c for mounting screws 17 are formed. Stupid hole 1 of relay tube 18
In 8c, at the same time during sanderch molding,
Alternatively, by processing after the molding, the core layer 18a
is exposed on the surface, and when the screw 17 is fitted, the screw 1
7 so that electrical continuity can be obtained. The shape of the area around the screw pilot hole 2d is such that t<h, where t is the thickness of the skin layer on the inner surface of the pilot hole and h is the thread height of the self-tapping screw 17, and the shape of the core layer of the pilot hole 2d is By making the inner diameter smaller than the thread system d of the screw 17, the screw 17 can be screwed into the pilot hole 2d of the lens fixing barrel 2, so that the thread 17a of the screw 17 can be inserted into the skin layer 2b. The core layer 2a of the lens fixed lens barrel 2 is broken and inserted into the core layer 2a to ensure electrical continuity with the layer 2a.

In Fig. 2b, the fixed lens barrel 2 and the relay barrel 18 are connected with the screw 1.
7 shows the coupled state, in which the core layer 2a of the lens fixed barrel 2 and the screw 17 are electrically connected via the screw thread 17a, and the screw 17 and the relay tube 18 are electrically connected.
The state in which the core layer 18a is electrically conductive is shown.

In addition, the lens fixed lens barrel 2 and relay barrel 1 as described above
Similarly to the coupling structure between the relay barrel 18 and the rear lens barrel 14, a coupling structure is provided that ensures electrical continuity via the screws 19.

FIGS. 3a and 3b show other structural examples of the prepared hole portion for screwing the molded product according to the present invention.

This example shows the pilot hole 5 for the screw of the sanderch molded product.
As shown in the figure, this is an example in which the shape of the screw hole 50d is provided with projecting portions such as 50b and 50b at both ends of the screw hole 50d. This is the core layer material 5
By increasing the escape area for the skin layer material 50b during injection of the screw 0a, it is possible to further reduce the thickness t of the skin layer around the pilot hole 50d. That is, the skin layer material 50 forms a hole circumferential surface 50c into which the shaft portion of the screw 51 is screwed into the resin injection space (cavity) for molding the molded product of the molding die shown in FIG. 3a.
A place is provided at both ends of the screw hole 50d for the screws b and 50b to escape. As a result, the skin layer material 50
The skin layer material 50b is pushed to both ends of the screw hole 50d by the injection of the core layer material 50a after the injection of the holes 50b and 50b, so that the skin layer material 50b on the circumferential surface 50c of the screw hole is as shown in FIG. 3a. It can be formed into a thin film. In addition, FIG. 3b shows that when the screw 51 is screwed in, the skin layer around the screw pilot hole is torn by the screw thread 51a, and the screw 51 and the core material 50a are electrically connected to each other by biting into the core layer 50a. FIG. 2B is a diagram illustrating a state in which the device is in a state where the device is in a state where the device is in a state where the device is in a state that is substantially the same as that shown in FIG. 2B.

Next, an example of manufacturing a multilayer resin molded product having a pilot hole for screwing as described above will be described.

In the molding apparatus shown in FIG. 4, reference numerals 30 and 31 are fixed plates, and the fixed plates 30 and 31 are connected to the first injection cylinder 32A for injecting the skin layer resin material.
and sprues 30a, 30b connecting the second injection cylinder 32B for injecting the core layer resin material. 34 is a runner plate having a runner 34a, and 36 and 38 are molds provided with molding gaps.

The gate 34b for injecting the molten resin into the molding cavity from the runner plate 34 is a disk gate provided at the center of the front end surface 2e of the lens fixed lens barrel 2 of the molded product shown in FIG.

The operation of the molding device begins with injecting a predetermined amount of skin material from the first injection cylinder 32A into the gap through the sprue, runner, and gate. Polycarbonate resin or the like is used as the skin material.
After injecting a predetermined amount of the skin material, the core material is injected from the second injection cylinder through the gate. By injecting the core material, the skin material previously injected into the void is pressed against the peripheral wall of the void by the core material, yielding a molded product having a skin layer on the surface and a core layer at the core.

In particular, in the fixed lens barrel of this example, as shown in FIG. 2a, the skin material in the peripheral part 2f of the pilot hole 2d for screwing in the rear end 2c is pushed out to the peripheral part 2g of the pilot hole. Compared to the entire skin layer of the fixed lens barrel 2, the wall thickness is as thin as t. Therefore, the prepared hole 2d of the lens fixed barrel 2 in this example is
Since the skin layer is thin, the skin layer is easily broken by the self-tapping action of the screw, and the effect is that it is easy to ensure electrical continuity between the screw 17 and the core layer 2a.

〔Effect of the invention〕

As described above, the resin molded product of the present invention is
For example, when making a fixed lens barrel, which is a component of a camera barrel, using a sandwich molding method with a laminated structure of a skin layer and an electrically conductive core layer, the self-tapping screw hole for attaching another component is required. , has a structure that automatically establishes electrical continuity between the screw and the core layer when the screw is screwed in,
Therefore, the resin molded product has an electromagnetic wave shielding effect and has good assembly properties.

[Brief explanation of drawings]

Figure 1 is a diagram showing an example of a general configuration of a lens barrel of a camera incorporating a molded product according to the present invention, and Figures 2a and b are diagrams showing the prepared hole portion for screwing the molded product according to the present invention. Figures 3a and 3b are diagrams for explaining the state in which the screw member is screwed into the screw member, and FIGS. FIG. 4 is a diagram showing an example of a molding apparatus used to manufacture the molded product of the present invention, and FIG. 5 is an example of a general configuration of a conventional camera lens barrel. FIG. DESCRIPTION OF SYMBOLS 1... Focusing lens holder, 2... Lens fixed lens barrel, 2a... Core layer, 2b... Skin layer, 2c...
...Rear end surface part, 2d... Pilot hole for screwing, 2e
... Tip, 2f ... Skin layer, 2g ... Preparation hole periphery, 3, 4 ... Lens holder, 5 ... Guide bar, 6 ... Cam ring, 6a, 6b ... Cam lift,
6d, 6e...Diameter fitting portion, 7...Zoom operation ring,
7a... Inner protrusion, 8... Front mask plate, 9...
... Rear mask plate, 12 ... Diaphragm, 13 ... Lens holder, 14 ... Rear fixed tube, 15 ... Screw, 1
6...Mount holder, 17...Screw, 17a...
...Screw thread, 18...Relay pipe, 18a...Core layer, 1
8b... skin layer, 18c..., 19... screw,
20...screw, 21...imaging element unit, 3
0, 31... Fixed plate, 30a, 31b...
Sprue, 32A...First injection cylinder, 32B
...Second injection cylinder, 34...Runner plate, 34a...Runner, 34b...Gate, 3
6, 38... Mold, 50... Molded product, 50a...
Core layer material, 50b...Skin layer material, 50d...
...Prepared hole for screw, 51...screw, 51a...screw thread.

Claims (1)

[Claims] 1. A first layer having a layered structure including a core layer made of a conductive material and a skin layer made of an insulating material covering the surface of the core layer, and formed with a through hole provided in a part of the core layer. A screw that is formed to have a layered structure including a resin molded product, a core layer made of a conductive material, and a skin layer made of an insulating material covering the surface of the core layer, and has an inner surface covered by the skin layer due to the molding. The core layer is formed to include a pilot hole for screwing, and the inner diameter of the core layer covered with the skin layer in the pilot hole for screwing is smaller than the outer diameter of the thread of the screw member screwed into the pilot hole. and a second resin molded product provided in the skin layer, and the first and second resin molded products are coupled by screwing the screw member into the through hole and the pilot hole, and the skin layer A multilayer resin molded product characterized in that the screw member and the core layer are electrically connected to each other when broken.