JPH06109960A - Lens barrel - Google Patents

Abstract

PURPOSE:To easily assemble a lens holder and a cam barrel and to prevent the faulty actions of the cam barrel and the lens holder caused by the deformation of the can barrel. CONSTITUTION:A cam pin 28 is attached to the outer periphery of the lens holder 26 in which a lens 25 is fitted, and then the lens holder 26 is inserted in the inner peripheral side of a guide barrel 23 with a spring 27 while the cam pin 28 is inserted in a straight advance groove 23a formed on the guide barrel 23 of a straight advance guide 20 from the opening of the groove 23. While the spiral groove 30b of a rotating cam ring 30 is engaged with the cam pin 28 from the opening side, the ring 30 is fitted on the outer periphery of the guide barrel 23. Thereafter, a cam stop ring 31 is fixed on an end face 23b facing the assembling direction of the guide barrel 23 of the guide 20, so that the pulling-out of the ring 30 from the guide barrel 23 caused by the force of the spring 27 is prevented. Then, the ends of the guide barrels 23 divided into three in a peripheral direction by the groove 23a are mutually connected so as to prevent deformation in a diameter direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens barrel for moving a lens in the optical axis direction by relatively rotating a pair of coaxially assembled cam barrels.

[0002]

2. Description of the Related Art As this type of lens barrel, for example, one disclosed in Japanese Patent Laid-Open No. 63-98638 is known. This lens barrel will be described below with reference to FIG. As shown in the figure, the lens barrel of the above publication has a first cam barrel 1 in which three rectilinear grooves 1a penetrating in the radial direction extend parallel to the axis, and an outer peripheral side of the first cam barrel 1. 3 spiral grooves 2 (only two of which are shown in the figure) that are fitted to the inner peripheral surface and twisted around the axis
The second cam cylinder 2 having a formed therein, the lens holder 4 fitted on the inner circumference side of the first cam cylinder 1 and having the lens 3 fitted on the inner circumference thereof, and provided on the outer circumference of the lens holder 3 in a protruding manner. The cam pin 5 that penetrates the straight groove 1a of the first cam barrel 1 and has its tip engaged with the spiral groove 2a of the second cam barrel 2, the flange 1b of the first cam barrel 1, and the lens holder 4. A spring 6 which is interposed between and presses the cam pin 5 toward the spiral groove 2a, and is fixed to the flange 1b of the first cam barrel 1 by three screws 7, and the second cam by the elastic force of the spring 6 is provided. And a cam stopper ring 8 for preventing the cylinder 2 from coming off in the axial direction. When the second cam barrel 2 is rotated around the first cam barrel 1, the cam pin 5 is pushed out in the optical axis direction of the lens 3 according to the twist angle of the spiral groove 2a, and the lens holder 4 is moved in the optical axis direction. By moving, the focal length of the lens 3 is adjusted.

In the above lens barrel, both the straight groove 1a of the first cam barrel 1 and the spiral groove 2a of the second cam barrel 2 face the end face 1 in the assembling direction of the cam barrels 1, 2.
Since the lens holder 4 and the second cam barrel 2 are assembled to the first cam barrel 1, the cam pins 5 are attached to the outer periphery of the lens holder 4 and then the lens holder 4 is opened. Inserted into the first cam barrel 1 and inserted into the second cam barrel 2
You only have to cover it, and the work is easy.

[0004]

However, when the straight groove 1a of the first cam barrel 1 is opened to the end face 1c, the end portion of the first cam barrel 1 is divided in the circumferential direction and the rigidity is lowered. The end portions may be deformed in the radial direction and rub against the lens holder 4 and the second cam barrel 2, and the movement of the lens holder 4 and the second cam barrel 2 may be impaired. If the straight groove 1a is formed in a long hole shape without opening the end face 1c in order to eliminate this defect, the cam pin 5 interferes with the lens holder 4 and the lens holder 4 is formed.
Since the lens holder 4 cannot be fitted on the inner circumference of the cam cylinder 1, the screw hole for mounting the cam pin 5 and the straight groove 1a are aligned after the lens holder 4 is inserted into the cam cylinder 1, and the cam pin 5 is mounted from the outer peripheral side of the cam cylinder 1. There is a need. For this reason, the work becomes troublesome, and there is a possibility that the operation of the lens barrel and the deterioration of the optical performance may occur due to the mounting failure of the cam pin 5.

An object of the present invention is to provide a lens barrel in which the work of assembling the lens holder and the cam barrel is easy and the malfunction of the cam barrel and the lens holder due to the deformation of the cam barrel can be prevented.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to FIG. 1 showing an embodiment.
A first cam barrel 23 having a cam groove 23a of
Is fitted on the outer peripheral side of the cam cylinder 23, and at least on the inner peripheral surface
Second cam groove 30b extending in a direction diagonally intersecting with the cam groove 23a, and the second cam cylinder 30 is formed, and the lens 25 is fitted on the inner circumference side of the first cam cylinder 23 and has the lens 25 on the inner circumference. The fitted lens holder 26, the cam pin 28 protruding from the outer periphery of the lens holder 26, penetrating the first cam groove 23a, and having the tip engaged with the second cam groove 30b, the first and second The present invention is applied to a lens barrel including a retaining member 31 that prevents relative movement of the cam barrels 23 and 30 in the axial direction. And the above-mentioned purpose is the 1st, 2nd cam groove 23a, 30.
b is opened to the end faces 23b and 30c facing the mounting direction of the first and second cam barrels 23 and 30, and the retaining member 31 is fixed to the end face 23b facing the mounting direction of the first cam barrel 23 to fix the first cam barrel 23. This is achieved by connecting the ends of the first cam cylinder 23, which are divided in the circumferential direction by the cam groove 23a, to each other.

[0007]

In order to assemble the first and second cam barrels 23 and 30 and the lens holder 26, the cam pin 28 is attached to the lens holder 26, and then the cam pin 28 is attached to the first cam groove of the first cam barrel 23. The lens holder 26 is fitted on the inner peripheral side of the first cam cylinder 23 while being inserted into the groove through the opening of 23a. Then, the second cam cylinder 30 is fitted on the outer periphery of the first cam cylinder 23 while engaging the second cam groove 30b of the second cam cylinder 30 with the cam pin 28 from the opening side. After this,
The retaining member 31 is fixed to the end surface 23b of the first cam barrel 23 facing the mounting direction, and the first and second cam barrels 23, 3 are fixed.
In addition to preventing relative movement of 0 in the axial direction, the end portions of the first cam barrel 23 divided in the circumferential direction by the first cam groove 23a are connected to each other to prevent radial deformation.

Incidentally, in the section of means and action for solving the above-mentioned problems for explaining the constitution of the present invention, the drawings of the embodiments are used to make the present invention easy to understand. It is not limited to.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIGS. In these drawings, reference numeral 10 denotes a cylindrical dark box which serves as a base of the lens barrel, and a drive cylinder 11 is rotatably fitted on the inner periphery thereof. A tooth portion 11a is formed on the outer circumference of one end side of the drive cylinder 11 so as to project in the radial direction. The tooth portion 11a is formed on the inner circumference of the dark box 10 to have a larger diameter portion 10a.
The lock ring 12 is attached to one end of the dark box 10 after being stored in
It is fixed by 3 and the movement of the drive cylinder 11 with respect to the dark box 10 in the axial direction is prevented. Hereinafter, the axial direction of the dark box 10 is referred to as the optical axis direction, the left side of FIG. 2 is referred to as the front of the lens barrel, and the right side thereof is referred to as the rear of the lens barrel.

The tooth portion 11a of the drive cylinder 11 is exposed to the outside from a not-shown notch formed in the peripheral surface of the dark box 10 and meshes with a not-shown lens drive gear. The lens drive gear is connected to a lens drive motor (not shown), and the drive cylinder 11 rotates around the axis according to the rotation angle of the output shaft of the lens drive motor. A female helicoid screw 11b is provided on the inner circumference of the drive cylinder 11.
The female helicoid screw 11b is engraved with
Male helicoid screw 14a of the inner cylinder 14 fitted to the inner circumference of the
Screw together. A key groove 14b formed on the inner circumference of the inner cylinder 14 is engaged with a straight key 16 fixed to the other end of the dark box 10 with a screw 15 to prevent its rotation. Therefore, when the drive cylinder 11 rotates, the inner cylinder 14 moves straight in the optical axis direction by an amount corresponding to the rotation angle.

A first group lens 17 and a shutter ring 18 incorporating a shutter blade (not shown) are arranged at one end of the inner cylinder 14. The shutter ring 18 is fixed to the inner cylinder 14 by a screw 21 together with a straight guide 20 inserted into the inner cylinder 14 from the rear of the lens barrel, and moves integrally with the inner cylinder 14 in the optical axis direction.

The straight guide 20 comprises a flange 22 fixed to the inner cylinder 14, and a guide cylinder 23 projecting cylindrically from the flange 22. The guide tube 2 has the guide tube 2
Three linearly extending grooves 23a penetrating radially 3 are provided in a straight line toward the optical axis direction, and these linearly extending grooves 23a are opened in an end surface 23b of a guide tube 23 facing the rear of the lens barrel. . 2 inside the guide tube 23 of the straight-ahead guide 20.
A lens holder 26 containing a group lens 25, and a spring 27 for urging the lens holder 26 toward the rear of the lens barrel.
And are inserted from the rear of the lens barrel. Lens holder 2
The same number of cam pins 28 as the rectilinear grooves 23a are attached to the outer circumference of 6 by screwing the threaded portions 28a thereof into the lens holder 26 at equal intervals in the circumferential direction. These cam pins 28 are inserted into the rectilinear groove 23a from the opening end of the rectilinear groove 23a when the lens holder 26 is assembled to the guide cylinder 23 of the rectilinear guide 20.

A rotating cam ring 30 is fitted on the outer peripheral side of the guide cylinder 23 of the straight guide 20 from the rear of the lens barrel. The rotary cam ring 30 has a key 30 provided at one end thereof.
a is engaged with a key groove 11c provided on the inner circumference of the drive cylinder 11 and is rotatable integrally with the drive cylinder 11. Rotating cam ring 30
3 spiral grooves 30b twisted around the optical axis are formed at equal pitches in the circumferential direction, and these spiral grooves 30b face the end surface 30c facing the mounting direction of the rotary cam ring 30 to the guide cylinder 23.
To open. When the rotary cam ring 30 is assembled to the guide cylinder 23, the spiral groove 30b engages with the tip of the cam pin 28 protruding from the rectilinear groove 23a.

An annular cam stopper ring 31 is fixed to the end surface 23b of the straight guide 20 by three screws 32.
The cam stop ring 31 projects in the radial direction from the outer peripheral surface of the guide cylinder 23, and the rotary cam 30 is moved from the guide cylinder 23 to the lens by the force of the spring 27 transmitted to the rotary cam ring 30 via the lens holder 26 and the cam pin 28. Prevents the lens barrel from slipping out behind. Screw 32 for fixing cam stop ring 31
Are respectively threaded at the end portions of the guide cylinder 23 that is divided into three in the circumferential direction by the rectilinear groove 23a, so that the end portions of the guide cylinder 23 are connected to each other by the cam stop ring 31.

In the lens barrel having the above construction, the inner cylinder 14 moves in the optical axis direction together with the first group lens 17 in accordance with the rotation angle of the drive cylinder 11, and the rotary cam ring 30 moves. The cam pin 28 is rotated around the guide cylinder 23 of the rectilinear guide 20 integrally with the drive cylinder 11, whereby the cam pin 28 is guided in the rectilinear groove 23a and pushed out in the optical axis direction according to the twist angle of the spiral groove 30b. The group lens 25 moves in the optical axis direction while changing the relative distance to the first group lens 17.

In the lens barrel of this embodiment, the straight guide 2
The straight groove 23a of 0 and the spiral groove 30b of the rotary cam ring 30 are
Since the guide cylinder 23 of the straight guide 20 and the rotary cam ring 30 are open to the end faces 23b and 30c facing the assembling direction,
The cam pin 28 can be attached to the lens holder 26 first, and then the lens holder 26 and the rotating cam ring 30 can be attached to the guide tube 23 of the linear guide tube 20. That is, the cam pin 28 assembled to the lens holder 26 is inserted into the groove from the opening of the rectilinear groove 23a, and the lens holder 2
6 is fitted on the inner peripheral side of the guide cylinder 23 of the straight guide 20, and the rotary cam ring 30 is mounted on the outer periphery of the guide cylinder 23 while the spiral groove 30b of the rotary cam ring 30 is engaged with the cam pin 28 from its opening side. Since it suffices to fit the cam pin 28, the work is easier than when the cam pin 28 is assembled later, and the cam pin 2
8 is less likely to cause assembly failure.

Further, since the end portions of the guide cylinder 23 divided into three by the rectilinear groove 23a are connected to each other by the cam stopper ring 31 and are prevented from being deformed in the radial direction, the lens holder 26 and the rotary cam ring 30 are connected. There is no possibility that the lens holder 26 and the rotary cam ring 30 may be deteriorated in operation due to strong friction with the guide tube 23. Since the cam retaining ring 31, which is an essential component for preventing the rotation cam ring 30 from coming off from the guide cylinder 23, is also used as the connecting member at the end portion of the guide cylinder 23, the number of components does not increase at all, and the lens barrel is assembled. There is no fear of increasing man-hours and production costs.

In the above embodiment, the guide cylinder 23 of the linear guide 20 is the first cam cylinder, the linear groove 23a of the guide cylinder 23 is the first cam groove, and the rotary cam ring 30 is the second cam cylinder. The spiral groove 30b of the rotary cam ring 30 constitutes a second cam groove, and the cam retaining ring 31 constitutes a retaining member. The first cam groove does not necessarily have to be provided parallel to the optical axis direction, and it is sufficient that the first cam groove and the second cam groove intersect obliquely. For example, the first cam groove may be a spiral groove and the second cam groove may be a rectilinear groove parallel to the optical axis. Without spirally penetrating the second cam groove, the second cam groove is formed like the spiral groove 2a of FIG.
It may be formed only on the inner peripheral surface of the cam cylinder. The retaining member is not limited to the annular shape, and may have any shape as long as the ends of the first cam barrel divided by the cam groove can be connected to each other.

[0019]

As described above, according to the present invention, since the first and second cam grooves are open at the end faces facing the assembling direction of the first and second cam barrels, the lens holder can be mounted on the lens holder as usual. The cam barrel and the lens holder can be assembled after the cam pin is assembled, and the work is easy. Since the end portion of the first cam barrel, which is divided in the circumferential direction by the first cam groove, is connected by the retaining member to prevent the radial deformation, the movement of the lens holder and the second cam barrel is prevented. It is always kept smooth. Moreover, since the end portion of the first cam barrel is connected by the retaining member that has been conventionally provided to prevent the relative movement of the first and second cam barrels, the number of parts does not increase. There is no fear that the number of steps for assembling the lens barrel and the production cost will increase.

[Brief description of drawings]

FIG. 1 is a perspective view showing a configuration of a lens barrel according to an embodiment of the present invention.

2 is an axial sectional view of the lens barrel of FIG. 1 in an assembled state.

FIG. 3 is a perspective view showing a configuration of a conventional lens barrel.

[Explanation of symbols]

 20 rectilinear guide 23 guide cylinder of rectilinear guide 23a rectilinear groove 23b end face facing the assembling direction of the guide cylinder 25 second group lens 26 lens holder 28 cam pin 30 rotating cam ring 30b spiral groove 30c end face facing the assembling direction of the rotating cam ring 31 cam stopper ring

Claims (1)

[Claims] 1. A first cam barrel having a first cam groove formed therethrough in a radial direction, and a first cam barrel fitted on the outer peripheral side of the first cam barrel and having the first cam barrel at least on the inner peripheral surface thereof. The second that extends in the direction that intersects the cam groove at an angle
Second cam barrel having a cam groove formed therein, a lens holder fitted on the inner circumference side of the first cam barrel and having a lens fitted on the inner circumference thereof, and projectingly provided on the outer circumference of the lens holder. A cam pin that penetrates the first cam groove and has a tip engaged with the second cam groove; and a retaining member that prevents relative movement of the first and second cam barrels in the axial direction. In the lens barrel including the first and second cam grooves, the first and second cam grooves are opened at end faces of the first and second cam cylinders facing the assembling direction, and the retaining member is provided on the first cam cylinder. A lens barrel characterized in that the end portions of the first cam barrel fixed to the end face facing the assembling direction and divided in the circumferential direction by the first cam groove are connected to each other.