JP3191422B2 - Method for manufacturing cam ring of lens barrel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cam ring having a cam groove used for a zoom lens barrel or the like, and more particularly to an improved mold for forming such a cam ring with a synthetic resin material. The cam ring of the lens barrel formed by the division method
It relates to a manufacturing method .

[0002]

2. Description of the Related Art Conventionally, the cam ring of this type of zoom lens barrel is formed by forming a cam groove by cutting using a metal material, or by using a synthetic resin material to make it inexpensive. The mold was divided and processed in the outer peripheral direction.

[0003]

However, when a cam groove is formed by cutting using a metal material, the accuracy is high but the processing time is longer than that of molding using a synthetic resin material. Therefore, it is inevitable that it will be expensive.

[0004] On the other hand, in the case of the latter molding process in which the mold is divided in the outer peripheral direction using a synthetic resin material, only the cam surface that coincides with the direction in which the mold is removed is a surface perpendicular to the optical axis. However, most of the surfaces that do not coincide with the drawing direction of the mold are undercut, so that they are formed to be inclined with respect to the drawing direction. That is, the cam surface is not a surface perpendicular to the optical axis, but a surface inclined with respect to the optical axis. In this manner, if the surface is inclined with respect to the optical axis, the contact surface with the cam pin that penetrates the cam groove comes into line contact, so that the corner is easily worn. Further, in order to make the contact surface with the cam pin flat, the cam pin must be tapered in accordance with the inclination of the cam surface, which makes the processing of the cam pin difficult.

Accordingly, the present invention solves the above-mentioned problems and uses a synthetic resin material so that the cam surface of all the surfaces is perpendicular to the optical axis. of the ring
It is intended to provide a manufacturing method .

[0006]

In order to solve the above-mentioned problems, a method of manufacturing a cam ring of a lens barrel according to the present invention comprises forming a cam groove having a cam surface having first and second side surfaces with a synthetic resin material. in the method <br/> of the cam ring of the lens barrel for molding was used to divide the previous SL cam surfaces in two stages in a direction perpendicular to the optical axis
A first mold that molds the first side surface on the first step side and is movable in a second direction substantially perpendicular to the first side surface in a certain area of the cam groove ; The cam surface is perpendicular to the optical axis
The second side surface on a second stage side divided into two stages in a vertical direction
And forming a pair on the second side surface in an area of the cam groove .
And a second mold movable in a substantially perpendicular first direction.
Using said first forming shape type unplug in a second direction, the second forming shape type unplug the first direction, the optical axis and a plane perpendicular to the cam surface in all respects It is characterized by being molded to become
I do .

[0007]

[0008]

In the present invention, a cam surface formed using a synthetic resin material is divided into two stages in a direction perpendicular to the optical axis to form a first side surface (left side surface) of the cam surface. ) Is the second
(Right side) and the second side surface (right side) of the cam surface has a cam groove shape that can be pulled out in the first direction (left direction). Direction and second
(Right and left), and the cam surface is perpendicular to the optical axis on all surfaces, so that the contact surface with the cam pin can be contacted.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments will be described in more detail with reference to the drawings and the like. FIG. 1 is a sectional view showing an embodiment of a cam ring of a lens barrel according to the present invention, and FIG. 2 is an explanatory sectional view of a one-unit lens moving frame having a cam groove.

This embodiment is applied to a zoom lens barrel in which the second group lenses L2 and L3 move with respect to the first group lens L1. The first-group lens holding frame 1 has a first-diameter lens L1 held by a small-diameter inner diameter portion 1a, a female helicoid 1c formed on the left of an inner peripheral portion of a large-diameter outer diameter portion 1b, and a right inner peripheral portion thereof. Is formed with a segment gear 1d.

The first lens group moving frame 2 has a male helicoid 2a screwed into the female helicoid 1c of the first lens group holding frame 1 on the outer peripheral portion, and its inner peripheral portion 2d is fitted to the outer peripheral portion 3a of the zoom drive ring 3. are doing. As shown in FIG. 2, a group of zooming cam grooves 2 </ b> A including a left side wall 2 b and a right side wall 2 c is formed in the center, and the cam grooves 2 </ b> A are fixed to the zoom drive ring 3. The cam pin 4 penetrates. As shown in FIG. 2, the cam groove 2A of the one-group lens moving frame 2 has a left side wall 2b formed on the outer side of the line LL and a right side wall 2c on the inner side of the line LL. Of the cam groove 2A. That is, the cam groove 2A
Is configured as described above, the mold A may be slid in the direction of arrow A, and the mold B may be slid in the direction of arrow B, as shown in FIG. This is the same as the drawing direction, and there is no particular problem in molding. Moreover,
Since the side walls 2b, 2c on both sides of the cam groove 2A are perpendicular to the optical axis, a cam pin having the same shape as that of the related art can be used. Further, a guide groove 2e parallel to the optical axis is provided on the outer peripheral portion of the one-group moving frame 2, and a straight key 6c provided on the left end of the fixed cylinder 6 is engaged. The one-group moving frame 2 has a structure that cannot rotate but can move only along the optical axis.

The zoom drive ring 3 has a cam pin 4 fixed at a center portion of an outer peripheral portion 3a by a nut 5, a ring-shaped projection 3c provided at a center portion of an outer peripheral portion 3e, and an inner periphery of the fixed cylinder 6. Since it is engaged with the circumferential groove 6a provided in the portion 6b, the zoom drive ring 3 cannot move in the optical axis direction, but is rotatable about the optical axis. At the right end of the zoom drive ring 3, a protrusion 3d
Since the projection 3d is engaged with a groove 7b of a projection 7a provided to extend inward from the zoom ring 7 to be described later, the zoom drive ring 3 and the zoom ring 7 , So as to rotate integrally about the optical axis. Further, a female helicoid 3b is provided on an inner peripheral portion of the zoom drive ring 3, and the female helicoid 3b is screwed with a male helicoid 8a provided on an outer peripheral portion of the second group moving frame 8 described later. ing.

The cam pin 4 is fixed to the center of the outer peripheral portion 3a of the zoom drive ring 3 by a nut 5, and the tip of the cam pin 4 penetrates into the cam groove 2A of the group moving frame 2.
The fixed cylinder 6 has a zoom drive ring 3 fitted on an inner peripheral portion 6b, and a zoom ring 7 fitted on the outer peripheral portion so as to be rotatable about an optical axis. The second group moving frame 8 has the second group lenses L2 and L3 fixed on the inner periphery, the male helicoid 8a on the outer periphery, and the inner lens of the zoom drive ring 3. It is screwed with the female helicoid 3b. Further, a guide groove 8b parallel to the optical axis is provided on the same outer peripheral portion, and the guide groove 8b is engaged with a key 6d provided on the inner peripheral portion of the fixed cylinder 6 in parallel with the optical axis. The second group moving frame 8 cannot rotate, but can move only along the optical axis. The coupling shaft 9 is a shaft for transmitting the driving force from the camera body to the first lens group holding frame 1 during automatic focusing.

When performing zooming, when the zoom ring 7 is rotated, the zoom drive ring 3 and the zoom ring 7 are configured to rotate integrally about the optical axis. Rotate at the same time. Since the female helicoid 3b provided on the inner periphery of the zoom drive ring 3 is screwed with the male helicoid 8a provided on the outer periphery of the second group moving frame 8, the female helicoid 3b is configured to be unable to rotate. The second group moving frame 8 moves by a predetermined amount along the optical axis. At the same time, the outer peripheral portion 3a of the zoom drive ring 3
The cam pin 4 fixed by a nut 5 at the center of the cam frame 4 also rotates, and the tip of the cam groove 2A of the group moving frame 2 has a structure that cannot rotate but can move only along the optical axis. Since it has penetrated, the one-group moving frame 2 is also moved by a predetermined amount along the optical axis in accordance with the rotation angle of the zoom drive ring 3 to perform zooming.

According to this embodiment, the dies A and B are pulled out in the direction where the cam surface does not exist.
The weight of the first lens group moving frame 2 can be further reduced. Further, since the contact area with the zoom drive ring 3 and the like is reduced, the rotation is smooth. In this embodiment, the curved cam groove has been described, but the present invention can be similarly applied to a linear cam groove provided to be inclined with respect to the optical axis.

[0016]

As described above, according to the present invention, a molding surface formed by using a synthetic resin material is divided into two stages in a direction perpendicular to the optical axis to form a first side surface of the cam surface. Is drawn in the second direction, and the forming die forming the second side surface of the cam surface has a shape of a cam groove that can be pulled out in the first direction. In addition to a simple structure that only opens in the direction, the cam surface is perpendicular to the optical axis on all surfaces, so the contact surface with the cam pin can be contacted, and the cam groove is made of inexpensive material. Can be manufactured, and a durable shape can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a cam ring of a lens barrel according to the present invention.

FIG. 2 is an explanatory cross-sectional view of a one-unit lens moving frame having a cam groove according to an embodiment.

[Explanation of symbols]

 L1 First group lens L2, L3 Second group lens 1 First group lens holding frame 2 First group lens moving frame 2A Cam groove 3 Zoom drive ring 4 Cam pin 5 Nut 6 Fixed cylinder 7 Zoom ring 8 Second group moving frame 9 Coupling shaft

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G02B ^7/ 02-7/10

Claims (1)

(57) [Claims] 1. A first and a direction perpendicular to the optical axis in the manufacturing process of the cam ring of the lens barrel for molding using a cam groove synthetic resin material, a pre-Symbol cam surface having a cam surface having a second side 1st stage side divided into 2 stages
The first side surface of the cam groove is formed and is movable in a second direction substantially perpendicular to the first side surface in a certain area of the cam groove.
First mold and a second stage side where the cam surface is divided into two stages in a direction perpendicular to the optical axis.
Is formed, and is movable in a first direction substantially perpendicular to the second side surface in a certain area of the cam groove.
By using the ability of the second mold, the first formed shape type unplug in a second direction, the second forming shape type unplug the first direction, of all the cam surfaces A method of manufacturing a cam ring of a lens barrel, characterized in that the surface is formed so as to be perpendicular to the optical axis.