JPH0618757A - Cam ring for lens barrel - Google Patents

Abstract

PURPOSE:To make a contact surface with a cam pin surface abut and to manufacture a cam groove by an inexpensive material by making the whole of a cam surface perpendicular to an optical axis. CONSTITUTION:The cam surface formed by using a synthetic resin material is divided to two stages in the perpendicular direction to the optical axis. Since the cam groove is shaped so that a mold(metallic mold) forming the first side surface(left side surface) of the cam surface can be drawn in the second direction (right direction) and a metallic mold forming the second side surface(left side surface) of the cam surface can be drawn in a first direction (left direction), such simple structure that the cam surface can be opened in the first and the second directions(left and right) is obtained. Besides, since the whole of the cam surface becomes vertical to the optical axis, the contact surface with the cam pin 4 can be made the surface abutting. That means, since the metallic mold is drawn in the direction where the cam surface does not exist, the part thereof is not made thick and a one group lens moving frame 2 can be made lighter in weight. Besides, since a contacting area with a zoom driving ring 3 or the like is made small, smooth rotation is attained.

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 molding such a cam ring with a synthetic resin material. The present invention relates to a cam ring of a lens barrel formed by a dividing method.

[0002]

2. Description of the Related Art Conventionally, a cam ring of a zoom lens barrel of this type is formed by cutting a cam groove with a metal material, or is made of a synthetic resin material so as to be manufactured at low cost. The mold was divided in the outer peripheral direction and processed.

[0003]

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

On the other hand, in the case of the latter molding process in which the mold is divided in the outer peripheral direction by using the synthetic resin material, only the cam surface which coincides with the drawing direction of the mold 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 the shape is 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 to the optical axis. As described above, when the surface is inclined with respect to the optical axis, the contact surface with the cam pin that penetrates into the cam groove comes into line contact, and thus the corners are easily worn. Further, in order to make the contact surface with the cam pin contact with the surface, the cam pin must be tapered in accordance with the inclination of the cam surface, which makes it difficult to process the cam pin.

Therefore, the present invention solves the above problems and uses a synthetic resin material so that the cam surface is a surface perpendicular to the optical axis on all surfaces. It is intended to provide a ring.

[0006]

In order to solve the above-mentioned problems, the cam ring of the lens barrel according to the present invention has first and second cam rings.
In the cam ring of the lens barrel in which the cam groove having the cam surface having the side surface is molded using a synthetic resin material, the cam groove 2A has the cam surface divided into two stages in the direction perpendicular to the optical axis. , The second direction A in the range of the cam groove is cut out on the first step side, and only the first side surface 2b exists, and the first direction of the range in which the cam groove is present on the second step side. The direction B is notched, only the second side surface 2c is present, and the cam surface is a surface perpendicular to the optical axis on all surfaces.

The cam ring of the lens barrel according to the present invention is the cam ring of the lens barrel formed by molding a synthetic resin material into a cam groove having a cam surface having first and second side surfaces. The groove divides the cam surface into two steps in the direction perpendicular to the optical axis, and the molding die A forming the first side surface 2b is formed by drawing in the second direction A, and the second side surface 2c is formed. The forming die B to be formed is drawn out in the first direction B and formed, and the cam surface is a surface perpendicular to the optical axis on all surfaces.

[0008]

In the present invention, a molding die (die) which divides a cam surface formed of a synthetic resin material 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
In the direction (right direction) to form the second side surface (right side surface) of the cam surface has the shape of a cam groove that can be removed in the first direction (left direction). Direction and second
Since it has a simple structure that only opens in the direction (left and right), and the cam surface is a surface perpendicular to the optical axis on all surfaces, the contact surface with the cam pin can also be contacted.

[0009]

Embodiments will be described in more detail below 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 a sectional explanatory view of a first group 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. In the first group lens holding frame 1, the first group lens L1 is held by the small diameter inner diameter portion 1a, the female helicoid 1c is formed on the left side of the inner diameter portion of the large diameter outer diameter portion 1b, and the right inner circumference portion thereof is formed. A segment gear 1d is formed on the.

The first group lens moving frame 2 has a male helicoid 2a which is screwed with the female helicoid 1c of the first group lens holding frame 1, and an inner peripheral portion 2d of which is fitted to an outer peripheral portion 3a of the zoom drive ring 3. is doing. Further, as shown in FIG. 2, a group of zooming cam grooves 2A composed of a left side wall 2b and a right side wall 2c are formed in the central portion, and the zoom drive ring 3 is fixed to the cam grooves 2A. The cam pin 4 has penetrated. As shown in FIG. 2, in the cam groove 2A of the first lens group moving frame 2, only the left side wall 2b is formed on the cam groove 2A on the outer peripheral side of the line LL, and the right side wall 2c is formed on the cam groove 2A on the inner peripheral side of the line LL. Only are formed, and both are combined to form the cam groove 2A. That is, the cam groove 2A
Since it is configured in this way, as shown in FIG. 2, 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 for molding. Since it is the same as the drawing direction, there is no particular problem in molding. Moreover,
Since the side walls 2b and 2c on both sides of the cam groove 2A are surfaces perpendicular to the optical axis, the cam pin having the same shape as the conventional one can be used. Further, a guide groove 2e parallel to the optical axis is provided on the outer peripheral portion of the first group moving frame 2, and the straight advance key 6c provided at the left end portion of the fixed barrel 6 is engaged with the guide groove 2e. The first group moving frame 2 cannot rotate but has a structure that can move only along the optical axis.

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

The cam pin 4 is fixed to the central portion of the outer peripheral portion 3a of the zoom drive ring 3 by a nut 5, and its tip portion penetrates into the cam groove 2A of the first group moving frame 2.
The fixed barrel 6 has a zoom drive ring 3 fitted to an inner peripheral portion 6b, and a zoom ring 7 fitted to an outer peripheral portion rotatably around an optical axis. The second lens group L2, L3 is fixed to the inner peripheral portion of the second group moving frame 8 and the male helicoid 8a is provided to the outer peripheral portion thereof, and is provided on the inner peripheral portion 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 since it engages with a key 6d provided on the inner peripheral portion of the fixed barrel 6 parallel to the optical axis, The second group moving frame 8 cannot rotate but is movable only along the optical axis. The coupling shaft 9 is a shaft for transmitting the driving force from the camera body to the first group lens holding frame 1 during automatic focusing.

When zooming is performed, when the zoom ring 7 is rotated, the zoom drive ring 3 and the zoom ring 7 are integrally rotated about the optical axis. Rotate at the same time. Since the female helicoid 3b provided on the inner peripheral portion of the zoom drive ring 3 is screwed with the male helicoid 8a provided on the outer peripheral portion of the second group moving frame 8, it is configured so as not to rotate. The second group moving frame 8 is moved 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 rotation also rotates, and the tip of the cam pin 4 is not formed in the cam groove 2A of the first group moving frame 2 which cannot move but moves only along the optical axis. Since it has penetrated, the first group moving frame 2 also moves a predetermined amount along the optical axis according to the rotation angle of the zoom drive ring 3 to perform zooming.

According to this embodiment, since the molds A and B are pulled out in the direction in which the cam surface does not exist, there is no wall thickness at that portion,
It is possible to further reduce the weight of the first group lens moving frame 2. Moreover, since the contact area with the zoom drive ring 3 and the like is reduced, the rotation is smooth. It should be noted that although the curved cam groove is described in this embodiment, the present invention can be similarly applied to a linear cam groove that is inclined with respect to the optical axis.

[0016]

As described above, according to the present invention, a molding die for forming a first side surface of a cam surface by dividing a cam surface formed of a synthetic resin material into two stages in a direction perpendicular to the optical axis. Is formed in the second direction, and the forming die that forms the second side surface of the cam surface is formed into the shape of the cam groove that can be drawn in the first direction. In addition to having a simple structure that only opens in the direction, the cam surface is a surface perpendicular to the optical axis on all surfaces, so the contact surface with the cam pin can also be contacted, and the cam groove is made of an inexpensive material. It has become possible to manufacture the above, and it has a durable shape.

[Brief description of 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 a cross-sectional explanatory diagram of a first group lens moving frame having a cam groove according to an example.

[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 barrel 7 Zoom ring 8 Second group moving frame 9 Coupling shaft

Claims (2)

[Claims] 1. A cam ring of a lens barrel, wherein a cam groove having a cam surface having first and second side surfaces is formed of a synthetic resin material, wherein the cam groove is perpendicular to the optical axis. Direction is divided into two stages, the first direction side is notched in the second direction in a range where the cam groove is present, only the first side surface is present, and the second direction side is provided with the cam groove. The cam ring of the lens barrel is characterized in that the first direction of a certain range is notched, only the second side surface is present, and the cam surface is a surface perpendicular to the optical axis on all surfaces. 2. A cam ring of a lens barrel, wherein a cam groove having a cam surface having first and second side surfaces is formed of a synthetic resin material, the cam groove being perpendicular to the optical axis. Divided into two stages, the forming die forming the first side surface is formed by drawing in the second direction, and the forming die forming the second side surface is formed by drawing in the first direction, The cam ring of the lens barrel, wherein the cam surface is a surface perpendicular to the optical axis on all surfaces.