JPH05341352A - Camera and cap for bayonet mount of interchangeable lens - Google Patents

Abstract

PURPOSE:To simplify the constitution of a metallic mold and to provide an inexpensive product by providing an aperture at a spot opposed to a bayonet pawl on the bottom part of a cap for a bayonet mount as to a cap for a bayonet mount CONSTITUTION:The cap 1 is made of plastic and provided with the bottom part 1a and three bayonet pawls 2a-2c on the cap side engaging with the bayonet pawls of the mount on an interchangeable lens side. The apertures 6a-6c by which the fixed metallic mold enters are formed at the spots opposed to the bayonet pawls 2a-2c on the bottom part 1a of the cap 1. The apertures 6a-6c exist as holes when the cap 1 is a simple substance, but they are closed by the bayonet pawl wider than the aperture when the cap 1 is attached to the interchangeable lens, thereby preventing the ingress of dust. The part of the undercut of a back part on the cap side conventionally formed by means of a split mold by the slide core of a movable side metallic mold is formed by means of the fixed side metallic mold.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens interchangeable camera and a cap attached to a body having a bayonet mount of an interchangeable lens.

[0002]

2. Description of the Related Art A conventional bayonet mount cap is mainly made of plastic and employs a split mold on the movable mold side as an injection mold to form an undercut of a bayonet claw.

[0003]

However, in the above-mentioned conventional molding means, it is impossible to increase the cost of the mold due to the use of the split mold and to shorten the molding time due to the multi-cavity production.
An object of the present invention is to provide a cheap cap by reducing the mold cost and increasing the production efficiency by simplifying the mold structure.

[0004]

In order to achieve the above object, the cap of the present invention is a plastic cap attached to a bayonet mout for connecting a camera side mount and an interchangeable lens side mount to each other in a bayonet manner. The side mount or the interchangeable lens side mount includes a cap side bayonet claw that engages with the mount side bayonet claw, and a bottom portion that covers the mount, and an opening is formed in a portion of the bottom portion that faces the cap side bayonet claw. In the conventional cap, the undercut of the bayonet claw on the cap side of the cap is formed by the fixed mold while the undercut is formed by the split core of the movable mold. It is characterized by

[0005]

According to the structure of the present invention, the undercut of the cap bayonet claw back portion which was conventionally formed by the split mold by the slide core of the movable mold is formed by the fixed mold. Therefore, the undercut portion is eliminated, and it is possible to manufacture with a simple two-sided structure. It should be noted that an opening is formed in a portion of the cap corresponding to the bayonet claw, and this opening is a state in which the bayonet claw of the camera and the interchangeable lens closes the opening when the cap of the present invention is mounted on the mount of the camera and the interchangeable lens. Therefore, when using the cap, there is no problem with invasion of dust and the like.

[0006]

EXAMPLE A cap according to the present invention will be described with reference to the drawings. An embodiment in which the present invention is applied to a mount cap for an interchangeable lens will be described with reference to FIGS. 1 to 7. FIG. 1 shows a state where the cap (1) is placed with the bottom (1a) facing upward in the figure, and FIG. 2 shows the bottom (1a).
It shows a state in which the cap (1) is placed with (a) facing down in the figure. As shown in FIGS. 4 to 7, the mount (11) of the interchangeable lens (10) includes bayonet claws (14a), (1).
4b) and (14c). Cap (1)
Is made of plastic, and the bottom part (1a) and the bayonet claws (14a), (14) of the interchangeable lens side mount (14)
b), three cap side bayonet claws (2a), (2b), (2c) that engage with (14c), and the cap (1)
The projection (3) that comes into contact with the bayonet claw (14) to function as a rotation stopper when mounted, and the projection (4) that comes into contact with the bayonet claw (14c) when the cap (1) is removed and functions as a rotation stopper. ) And the preset lever (15) of the interchangeable lens (10) when the cap (1) is attached to move the preset lever (15) from the position shown by the broken line in FIG. 4 to the position shown by the chain double-dashed line. The projection (5) for stopping the aperture of the interchangeable lens in the open position, and the projections (3) and (4) together with the bayonet claw (14).
a), (14b) and (14c), and projections (7) for restricting the meshing positions of the bayonet claws (2a), (2b) and (2c). Bayonet claws (2
a), (2b) and (2c) are provided at positions that divide the circumference into approximately three equal parts, and the claw widths of the corresponding bayonet claws (14a), (14b), (14b), (14b) of the interchangeable lens (10). 1
It is sufficient that the width is smaller than the width of 4c), and the width is set to an appropriate value in consideration of the mold construction and dust intrusion when the cap is attached.

FIGS. 5 to 7 show line segments AB,
The cross section in AC and AD is shown. 5 shows the engagement state of the projection (5) and the preset lever (15), FIG. 6 shows the engagement state of the bayonet claws (2a) and (14a), and FIG. 7 shows the engagement state of the projection (3) and the bayonet claw (14a). The engagement state is shown. At the bottom (1a) of this cap (1),
An opening (6a) for the fixed mold to enter, is provided at a portion facing the bayonet claws (2a), (2b), (2c).
(6b) and (6c) are formed. This opening exists as a hole when the cap (1) is used alone, but is blocked by bayonet claws (14a), (14b), (14c) having a wider width when attached to the interchangeable lens (10).
It can prevent the intrusion of dust. Further, with respect to dust invasion, since the rear end face of the main body bayonet and the contact surface (P) of the cap (1) are circumferentially in close contact with each other, the invasion of dust into the lens barrel can be completely prevented.

FIG. 3 shows a fixed type (V) and a movable type (W).
The mold for injection molding of the cap (1) is made of a structure in which the molded product is separated from the mold by the protruding pin after the fixed mold (V) and the movable mold (W) are separated from each other. Is very simple. By using the two-sided mold shown in FIG. 3, a large number of molded products can be simultaneously molded by one mold. FIG. 13 shows a conventional injection molding die for a rear cap for an interchangeable lens, and the movable die is composed of three types of cores (X), (Y), and (Z). After injection, three types of cores (X) on the movable side with respect to the fixed mold (U),
(Y) and (Z) move at the same time and move away from the fixed mold (U), and then the conical core (Z) at the movable side moves, and the back of the bayonet claws (2a), (2b) and (2c). The molded product is separated from the mold by the protruding pin provided on the movable mold outer shape core (Y) that escapes the undercut portion of the mold. In the die shown in FIG. 13, three types of movable cores (X), (Y), (Z) are used.
Since there is a need for a mold configuration to control the movement of the, the number of molded articles is limited to 2 to 3 at a time. In the mold of FIG. 3, it is possible to form the shape of the contact surface (P) that is undercut in the split mold of the mold of FIG.

8 to 12 show a cap (21) attached to the camera side mount. Camera (5
0) mount (20) has bayonet claws (20)
a), (20b) and (20c) are provided.
Cap (21) attached to this mount (20)
Is made of plastic and has a bottom portion (21a) and a recess (23) into which a lock pin (28) coming in and out of the camera side mount (20) can be fitted. The bayonet claws (22a), (22b) and (22c) are provided on the circumference in approximately three equal positions, and the claw width is the bayonet claw (20a), (20b) of the corresponding camera (50). And narrower than (20c). At the bottom (21a) of this cap (21), bayonet claws (22a), (22
The openings (26a), (26b) and (26c) for the mold to enter are formed at the locations corresponding to (b) and (22c), which are the same as those in the above-described embodiments of FIGS. 1 to 7. To 2
It can be injection-molded with a surface-structured mold. Cap (2
With 1) mounted on the mount (20), the bayonet claws (20a), (20b) and (20c) close the openings (26a), (26b) and (26c).
Dust is prevented from entering through the openings (26a), (26b) and (26c).

[0010]

As described above, according to the present invention, the mold structure is made very simple by providing an opening at the bottom of the cap for the bayonet mount at a position facing the bayonet claw. This makes it possible to reduce the cost required for cap production and to provide inexpensive products.

[Brief description of drawings]

FIG. 1 is a perspective view showing an interchangeable lens cap according to an exemplary embodiment of the present invention, with a bottom portion of the cap up.

FIG. 2 is a perspective view showing a state in which the bottom portion of the cap is located downward in the figure.

FIG. 3 is a cross-sectional view of a mold for manufacturing the cap.

FIG. 4 is a front view of the cap.

5 is a cross-sectional view of the cap and the interchangeable lens taken along a line AB in FIG.

6 is a cross-sectional view of the cap and the interchangeable lens taken along a line segment A-C in FIG.

7 is a cross-sectional view of the cap and the interchangeable lens taken along line A-D in FIG.

FIG. 8 is a perspective view showing a state in which the bottom portion of the camera cap according to the embodiment of the present invention is located lower in the figure.

FIG. 9 is a front view of the cap.

10 is a sectional view of the cap and the camera taken along the line AB in FIG.

11 is a cross-sectional view of the cap and the camera taken along line A-C in FIG.

FIG. 12 is a cross-sectional view of the cap and the camera taken along line A-D in FIG. 9.

FIG. 13 is a cross-sectional view of a conventional injection molding die for a rear cap for an interchangeable lens.

[Explanation of symbols]

1: Caps 2a, 2b, 2c: Cap side bayonet claws 6a, 6b, 6c: Opening 11: Interchangeable lens side bayonet mount 14a, 14b, 14c: Mount side bayonet claw 20: Camera side bayonet mount 20a, 20b, 20c: Mount Side bayonet claw 21: Camera cap 21a: Bottom 22a, 22b, 22c: Camera cap bayonet claw

Claims (1)

[Claims] 1. A plastic cap attached to a bayonet mout for connecting a camera-side mount and an interchangeable lens-side mount to each other by a bayonet, wherein the cap side of the camera-side mount or the interchangeable lens-side mount engages a mount-side bayonet claw. A cap comprising: a bayonet claw and a bottom portion that covers the mount, and an opening formed in a portion of the bottom portion facing the cap-side bayonet claw.