JPH0529013U - Lens barrel - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a lens barrel which is molded by plastic and which can accurately control the moving position of a moving lens without requiring high precision of parts. [Structure] The curved surface of the tip portion 12 of the cam follower 10 is always in contact with the inclined surface 4 of the cam groove 5 by an urging member 9 that urges in the direction of the cam groove 5. When the cam barrel 3 is rotated, the cam follower 10 is engaged at the intersection of the cam groove 5 of the fixed barrel 1 and the cam groove 6 of the cam barrel 3, so that the lens L2 is moved along with the moving lens frame 7 along the optical axis at the intersection. Then, the zooming operation is performed. Similarly, when the cam barrel 13 is rotated, the lens L1 and the lens frame 17 are moved in the optical axis direction,
Focusing operation is performed.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a lens moving device for focusing or zooming in a photographing lens, and more particularly to a lens barrel having a lens moving device made of a plastic molding.

[0002]

[Prior Art]

 As a device for controlling the movement of the moving lens in the optical axis direction for focusing or zooming, there is a cam device using a cam barrel. Conventionally, a metal material has been generally used as a main component of the cam device. However, this kind of metal material has a drawback that it is expensive and requires a high-precision finishing, so that the processing cost is also high. In order to solve these drawbacks, some cam devices using a plastic material as a main member of the cam device have been proposed. For example, in Japanese Utility Model Publication No. 2-33206, as shown in FIG. 3, two cam grooves 103 and 104 having different inclination angles 101 and 102 and the inclination angles 101 and 102 of the respective cam grooves 103 and 104 are equivalent. The cam followers 107 having different inclination angles 105 and 106 are brought into contact with each other, but in order to do this, the shape dimensions of the contact surfaces of the two cam grooves 103 and 104 and the cam follower 107 require considerably high processing accuracy. .

[0003]

[Problems to be solved by the device]

 In the case of forming each cam groove of the fixed cylinder and the cam cylinder with a plastic material, with the current technology, the cam surface has an inclination angle due to the draft, and as described above, the two cam grooves with the inclination angle have one When the cam followers of the book are engaged, it is practically difficult for the cam followers to contact the inclined surfaces of both cam grooves at the same time because of the lack of precision of the plastic molding.

An object of the present invention is to provide a lens barrel which simplifies the structure of a plastic molding die and which can accurately control the moving position of the moving lens with less play without requiring high precision of parts. With the goal.

[0005]

[Means for Solving the Problems]

 In order to achieve the above object, the present invention provides a lens mirror having a cam groove formed in a fixed barrel and a moving lens that is moved by a cam follower inserted at an intersection of the cam groove formed in the cam barrel. In the cylinder, both side surfaces of the cam groove of the cam cylinder are formed as inclined surfaces, and the tip end portion of the cam follower that contacts the inclined surface is a curved surface, and the cam follower is urged toward the cam groove of the cam cylinder. A biasing member is provided so that the curved surface of the cam follower is always in contact with the inclined surface, and the side surface of the cam follower and the cam groove of the fixed cylinder are in sliding contact with each other. Preferably, the curved surface of the cam follower is spherical, and the cam groove formed in the fixed barrel is a straight cam parallel to the optical axis formed of parallel facing surfaces.

[0006]

[Action]

 According to the structure of the present invention, the curved surface of the cam follower does not interfere with the curved surface of the cam follower due to the biasing member that biases the cam follower toward the cam groove of the cam barrel regardless of the accuracy of the cam groove. Since it always contacts with at least one of the inclined surfaces on both sides of the cam groove without receiving it, it is possible to prevent a clearance from being generated between the cam follower and the cam groove.

[0007]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view of the upper half of the lens barrel according to the present invention. In the figure, reference numerals 1 and 11 denote fixed barrels, and the fixed barrel 1 is coupled and integrally fixed to a lens mount 2 which can be mounted on a camera (not shown). The fixed barrel 11 is coupled to the fixed barrel 1 and integrated. It is fixed to. A cam groove 5 having an inclined surface 4 is formed as a helical groove on the inner surface of the cam barrel 3, and a fixed cam groove 6 parallel to the optical axis is provided on the fixed barrel 1. Further, a movable lens frame 7 holding a lens L2 is fitted in the inner diameter portion of the fixed barrel 1, and a boss 8 is radially provided on the outer peripheral portion of the movable lens frame 7, and the boss 8 is attached to the boss 8. The cam follower 10 biased by the biasing member 9 is fitted. The cam follower 10 engages with both cam grooves 5 at the intersection of the cam groove 5 of the cam cylinder 3 and the cam groove 6 of the fixed cylinder 1.

On the other hand, also in the fixed barrel 11, a cam groove 15 having an inclined surface 14 is formed as a helical groove in the cam barrel 13 fitted to the outer diameter portion, and the fixed barrel 11 is parallel to the optical axis. A straight cam groove 16 is provided. Further, similarly to the fixed barrel 1, a movable lens frame 17 holding the lens L1 is fitted in the inner diameter portion of the fixed barrel 11, and a boss 18 is radially provided on the outer peripheral portion of the movable lens frame 17. A cam follower 10 biased by a biasing member 9 is fitted on the boss 18. The cam follower 10 is engaged with both cam grooves at the intersection of the cam groove 15 of the cam cylinder 13 and the cam groove 16 of the fixed cylinder 11.

The tip end 12 of each cam follower 10 that is in contact with the inclined surfaces 4 and 14 of the cam grooves 5 and 15 formed in the cam barrel 3 and the cam barrel 13 is at least spherical. The side surface of each cam follower 10 that is in sliding contact with the rectilinear cam groove 16 may be a cylindrical surface or a flat surface as long as it has a slidable fitting degree.

Therefore, when the cam barrel 3 is rotated, the cam follower 10 is engaged with the cam groove 5 of the fixed barrel 1 and the cam groove 6 of the cam barrel 3 at the intersection, so that the moving lens frame 7 is moved along with the intersection. The lens L2 moves in the optical axis direction, and the variable power operation is performed.

When the cam barrel 13 is rotated, the cam follower 10 is engaged with the cam groove 15 of the fixed barrel 11 and the cam groove 16 of the cam barrel 13 at an intersection, so that the cam follower 10 moves together with the moving lens frame 17 in accordance with the intersection. The lens L1 moves in the optical axis direction, and the focusing operation is performed.

[0012]

[Effect of the device]

 According to the lens barrel of the present invention, in the lens barrel having the moving lens frame moved by the cam follower inserted at the intersection of the two cam grooves, the curved surface of the cam follower is provided on the inclined surface of the cam groove by the biasing member. Since they are always in contact with each other, the movement accuracy is not adversely affected even if the main members are made of plastic to reduce the weight and cost, and high accuracy is not required for each cam groove and cam follower. The cam follower moves along the cam groove without play, so that at least play in the optical axis direction is practically no problem, and an accurate moving position can be obtained.

[Brief description of drawings]

FIG. 1 is an upper half sectional view of an embodiment of a lens barrel according to the present invention.

FIG. 2 is a vertical cross-sectional view taken along line II-II shown in FIG. 1 showing a relationship between a cam follower and a cam groove in one embodiment of the lens barrel according to the present invention.

FIG. 3 is an upper half sectional view of a lens barrel according to a conventional technique.

[Explanation of symbols]

 1 Fixed Cylinder 2 Lens Mount 3 Cam Cylinder 4 Inclined Surface 5 Cam Groove 6 Straight Cam Groove 7 Moving Lens Frame 8 Boss 9 Biasing Member 10 Cam Follower 12 Tip Part

Claims (4)

[Scope of utility model registration request] 1. A lens barrel having a moving lens moved by a cam follower inserted at an intersection of a cam groove formed in a fixed barrel and a cam groove formed in the cam barrel, wherein a cam groove of the cam barrel is provided. Both side surfaces of the cam follower are formed into inclined surfaces, and the tip end portion of the cam follower that abuts on the inclined surface is a curved surface, and a biasing member that biases the cam follower in the direction of the cam groove of the cam cylinder is provided. Is a lens barrel in which the side surface of the cam follower and the cam groove of the fixed barrel are in sliding contact with each other. 2. The lens barrel according to claim 1, wherein the fixed barrel, the cam barrel and the cam follower are molded plastic products. 3. The lens barrel according to claim 1, wherein the curved surface of the tip end portion of the cam follower is at least a spherical surface. 4. The lens barrel according to claim 1, wherein the cam groove formed in the fixed barrel is a straight-moving cam that is parallel to the optical axis and has parallel facing surfaces.