JP2004151279A - Zoom lens barrel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a zoom lens barrel where a moving frame is advanced/retreated interlocked with the rotation of a cam frame, and which realizes the facilitation of the adjustment of a cam pin and a cam groove and the enhancement of the mechanical strength of an interlocking mechanism for the cam frame and the cam pin. <P>SOLUTION: The zoom lens barrel is equipped with the cam frame 12 where the wide cam groove 12a is spirally formed, a protection frame 15 provided to freely move in an optical axis direction so as to cover a moving frame 13, the cam pin 13a provided on the moving frame 13 and the cam pin 15a provided on the protection frame 15, and a coil spring 16 provided between one part 13c of the moving frame 13 and the front end flange 15b of the protection frame 15 so that the cam pin 13a may be brought into press-contact with one side groove surface of the cam groove 12a and the cam pin 15a of the protection frame 15 may be brought into press-contact with the other side groove surface of the groove 12a. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a zoom lens barrel provided in an imaging device such as a silver halide film camera, an electronic camera, and a video camera.
[0002]
[Prior art]
Conventionally, a zoom lens barrel of an imaging apparatus widely known includes a cam frame having a plurality of spirally formed cam grooves, and a plurality of moving frames supporting a lens for zooming. The cam pins provided on the moving frame are inserted into the cam grooves of the cam frame.
[0003]
In such a zoom lens barrel, when the cam frame is rotationally driven at a fixed position, the moving frame interlocked with the cam groove and the cam pin advances and retreats in the optical axis direction without rotating. Is displaced to perform zooming.
[0004]
[Problems to be solved by the invention]
In a zoom lens barrel having a cam frame as described above, it is difficult to adjust the degree of contact between a cam groove and a cam pin, and much time and money are spent on the adjustment.
[0005]
If the mechanical play between the cam pin and the groove surface of the cam groove is too small, the interlocking load of the cam pin becomes large, so that smooth interlocking by the cam frame becomes difficult, and the cam frame is driven by a motor. However, there is a problem that power consumption increases.
[0006]
In addition, when the mechanical play between the cam pin and the groove surface of the cam groove is increased, the moving frame is tilted with the cam pin as a fulcrum, so that the positional accuracy of the lens cannot be satisfied and the resolution is reduced. Occurs.
For this reason, it takes time to adjust the cam groove and the cam pin.
[0007]
On the other hand, as means for appropriately contacting the cam pins with the groove surfaces of the cam grooves, there is a configuration in which the cam pins are pressed against the cam grooves using an elastic body such as a leaf spring.
[0008]
However, such a configuration means can absorb mechanical play, but has a problem that the cam pin is disengaged from the cam groove when an external force such as an impact is applied to the lens barrel.
[0009]
If the deformation of the cam pin, which is an elastic body, is suppressed to prevent disengagement, the cam groove and the cam pin will be damaged, and the accuracy of the lens barrel will be affected.
[0010]
SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide a zoom lens barrel that facilitates adjustment of a cam pin and a cam groove and that increases mechanical strength of an interlocking mechanism between a cam frame and a cam pin.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, according to a first aspect of the present invention, there is provided, as a first invention, a cam frame which is driven to rotate, and a moving frame provided with a cam pin protruding into a cam groove of the cam frame. In a zoom lens barrel that moves in the optical axis direction in conjunction with the rotation of the zoom lens, a cam frame in which a wide cam groove is formed in a spiral shape, and a movable frame that is movable in the optical axis direction so as to cover the moving frame. The protection frame provided, the cam pins provided on the protection frame so as to protrude into the cam grooves, and the moving pins are provided with a repulsive force to move the cam pins into one side groove surface of the cam grooves and into the protection frame. And a biasing member for applying a force to press the cam pin against the other groove surface of the cam groove.
[0012]
In the zoom lens barrel according to the first aspect of the invention, the cam pins of the moving frame are pressed against one side groove surface of the cam groove, and the cam pins of the protection frame are pressed against the other side groove surface of the cam groove by the biasing force of the biasing member. It is only necessary to ensure the accuracy of only one side groove surface of the cam groove on which the cam pin of the moving frame slides, and since the cam pin is pressed against one side of the cam groove by the urging force, its mechanical play is absorbed. .
[0013]
Further, when an external force such as an impact is applied to the lens barrel, the protective frame retreats and absorbs the external force.
That is, since the cam pin of the protection frame is pressed against the other groove surface of the cam groove by the urging force, the cam pin separates from the other groove surface and retreats in the cam groove, so that the protection frame retreats according to the external force. And absorb the external force.
[0014]
As a result, the cam pins of the moving frame and the one side groove surface of the cam groove on which the cam pins slide are not affected, so that the cam pins are not disengaged by the external force and the cam pins and the cam grooves are not damaged. .
[0015]
According to a second aspect of the present invention, in the zoom lens barrel described above, there is provided a cam frame in which one cam groove is spirally formed with two cam grooves having the other cam groove wide. A zoom lens barrel is proposed in which a cam pin of the moving frame is inserted into one cam groove and a cam pin of the protection frame is inserted into the cam groove of the other cam frame.
[0016]
In the zoom lens barrel according to the second aspect of the invention, the cam pin of the moving frame projects into one of the cam grooves, and this cam pin is pressed against the side of the cam groove by the urging force. The play can be absorbed.
[0017]
Further, the cam pins of the protection frame protrude into the other cam grooves, and the cam pins are pressed against the side surfaces of the cam grooves.
Therefore, if the protective frame is retracted by an external force applied to the zoom lens barrel, the cam pin moves away from the side face of the cam groove and retreats in the wide cam groove, so that an impact external force applied to the zoom lens barrel is reduced. Can be absorbed, and the same effect as in the first invention can be obtained.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a perspective view of a camera equipped with a zoom lens barrel according to the present invention.
[0019]
The zoom lens barrel 11 of the camera 10 has a configuration in which the cam frame 12 is rotated at a fixed position by rotating the cam frame 12, and the moving frame 13 and other moving frames are moved forward and backward in association with the cam. Has become.
The moving frame 13 supports an objective lens 14 (front lens).
[0020]
FIG. 2 is a simplified sectional view showing a cam interlocking mechanism between the cam frame 12 and the moving frame 13 described above.
As shown in the figure, the cam frame 12 is a cylindrical frame body, and a wide cam groove 12a is spirally formed on the inner peripheral surface of the cam frame 12 and the cam pin 13a of the moving frame 13 and the protection frame 15 are formed in the cam groove 12a. The cam pin 15a is inserted.
[0021]
The cam groove 12a of the cam frame 12 is formed to have a sufficiently large groove width as compared with the diameter of the cam pin 13a or the cam pin 15a. In particular, the cam pin 15a is retracted by a small distance in the groove width direction within the cam groove 12a. It can move.
[0022]
The moving frame 13 is a cylindrical frame provided in the cam frame 12 with the protective frame 15 interposed therebetween, and the above-mentioned cam pin 13a is fixed to the rear end outer peripheral portion, and the objective lens 14 is supported on the front end side. is there.
[0023]
The protection frame 15 is a cylindrical frame that covers substantially the entirety of the moving frame 13 and is disposed between the cam frame 12 and the moving frame 13. 15a is fixed.
The protection frame 15 is movable in the optical axis direction (left and right direction in FIG. 1).
[0024]
In addition, the above-mentioned cam pins 13a are arranged at respective three-part positions on the outer peripheral portion of the rear end of the moving frame 13, and similarly, the cam pins 15a are arranged at respective three-division positions on the outer peripheral portion of the rear end of the protective frame 15. Is preferred.
[0025]
On the other hand, a stepped portion 13b is formed on the distal end side of the moving frame 13, and a coil spring 16 acting as a pressure expanding force is provided outside the stepped portion 13b.
The coil spring 16 is hooked on a part 13c of the moving frame 13 on one end and the front end flange 15b of the protection frame 15 on the other end. Advancing force is given to the protection frame 15 respectively.
[0026]
Therefore, since the cam pins 13a and 15a receive the moving force in the direction of being separated by the spring force of the coil spring 16, the cam pin 13a is pressed against one side groove surface (front surface of the groove) of the cam groove 12a, and the cam pin 15a is connected to the other side of the cam groove 12a. Press against the side groove surface (front of groove).
[0027]
In the zoom lens barrel configured as described above, since the cam pins 13a and 15a are driven by one cam groove 12a by the rotation of the cam frame 12, the movable frame 13 and the protection frame 15 move forward and backward integrally. Thus, the objective lens 14 is displaced and zooming is performed.
[0028]
Note that the moving frame 13 and the protection frame 15 are configured to move without rotating.
For example, the cam pins 13a and 15a are inserted into the cam grooves 12a through the rectilinear holes of the fixed frame, or the key grooves of the fixed frame provided on the movable frame 13 and the protection frame 15 are slid to protect the movable frame 13 from the protection. The frame 15 is held non-rotating.
[0029]
In the present embodiment, the moving frame 13 of the objective lens 14 is shown, but a rear lens group and a correction lens are also provided.
The rear group lens is configured to move its supporting and moving frame forward and backward in conjunction with the rotation of the cam frame 12.
[0030]
As can be seen from the above, the cam pin 13a of the moving frame 13 is driven in conjunction with the one groove surface of the cam groove 12a, so that the cam accuracy of the one groove surface may be increased, and the cam pin 13a is moved by the spring force. , So that mechanical play can be absorbed.
[0031]
On the other hand, the other groove surface of the cam groove 12a of the protection frame 15 to which the cam pin 15a presses does not need to be a particularly high-precision cam surface, and need not necessarily be formed to be parallel to one groove surface.
[0032]
FIG. 3 is a sectional view similar to FIG. 2, showing an operation state when the zoom lens barrel receives an external force 17 such as an impact.
As shown in the figure, when an external force 17 is applied from the front of the lens barrel, the external force 17 is received by the protection frame 15, so that only the protection frame 15 retreats against the spring force of the coil spring 16.
[0033]
That is, since the cam pin 15a is in pressure contact with the other groove surface of the cam groove 12a, the cam pin 15a is separated from the groove surface by an external force, retreats within a small distance in the cam groove 12a, and allows the protection frame 15 to retreat. .
[0034]
As a result, the external force 17 can be absorbed by the retreat of the protection frame 15 and does not affect the moving frame 13.
In particular, since the cam pins 13a of the moving frame 13 and the cam grooves 12a of the cam frame 12 are not affected by the external force 17, even when the camera is dropped, the disengagement of the cam pins 13a and 15a can be prevented. .
[0035]
Further, since the two cam pins 13a and 15a protrude into the cam groove 12a, the mechanical strength which does not affect the interlocking of the cam pin 13a and the cam groove 12a even when receiving an impact force from the upper and lower sides and the left and right of the lens barrel. It becomes a zoom lens barrel.
[0036]
FIG. 4 is a sectional view similar to FIG. 2 showing another embodiment.
The zoom lens barrel of this embodiment is characterized in that a cam groove 21a for projecting the cam pin 13a of the moving frame 13 into the cam frame 21 and a cam groove 25b for projecting the cam pin 15a of the protection frame 15 are formed. The other configuration is the same as that of the zoom lens barrel shown in FIG.
The members shown in FIG. 2 are denoted by the same reference numerals, and description thereof will be omitted.
[0037]
In the present embodiment, two cam grooves 21a and 21b are spirally provided on the cam frame 21. Among them, the cam groove 21a has a conventionally known groove width, and the cam groove 21b is a cam groove. The groove width is wider than the groove 21a, for example, about twice as large as the pin diameter.
[0038]
In this embodiment, in order to prevent the lens barrel length from increasing, the cam groove 21a is formed on the front side and the cam groove 21b is formed on the rear side, so that the cam pins 13a of the movable frame 13 are protected. The cam groove 21a is inserted into the cam groove 21a through the escape hole 15c formed in the frame 15.
[0039]
The zoom lens barrel thus configured receives a spring force in a direction in which the cam pin 13a and the cam pin 15a approach, so that the cam pin 13a is pressed against one side groove surface (in this case, the groove rear surface) of the cam groove 21a to protect the zoom lens barrel. The cam pin 15a of the frame 15 presses against the other groove surface of the cam groove 21b.
[0040]
Therefore, the mechanical play between the cam pin 13a and the cam groove 21a of the moving frame 13 is absorbed, and the cam pin 15a is moved by the cam groove 21b against the external force 17 applied to the zoom lens barrel as shown in FIG. Retreats into and absorbs.
As a result, the same effect as that of the zoom lens barrel shown in FIG. 2 can be obtained.
[0041]
FIG. 6 is a sectional view similar to FIG. 2 showing an improved example of the zoom lens barrel shown in FIG. In the zoom lens barrel shown here as an improved example, a ring frame 22 is attached to the rear end of the protection frame 15, and a coil spring 23 of a tension action is suspended between the ring frame 22 and the moving frame 13. The spring 23 applies a retreating force to the movable frame 13 and the advancement force to the protection frame 15.
[0042]
The other configuration is the same as that of the zoom lens barrel shown in FIG. 4, and FIG. 7 shows an operation state when an external force is applied.
[0043]
Although the embodiment of the present invention has been described above, the coil spring 16 provided as the biasing member can be made of an elastic material such as rubber or foam.
[0044]
In addition, the present invention can be applied not only to the moving frame for supporting the lens but also to a moving frame for supporting the shutter and the motor, and the zoom lens for rotating the cam frame by driving the motor. The same applies to the lens barrel.
[0045]
【The invention's effect】
As described above, according to the present invention, since the cam pin of the moving frame is pressed against one side groove surface of the cam groove by the urging force of the urging member, the adjustment of the mechanical play between the cam pin and the cam groove becomes extremely easy.
[0046]
In addition, the cam pin of the moving frame and the cam pin of the protection frame are inserted into the cam groove of the cam frame, so the mechanical strength of the interlocking mechanism between the cam pin and the cam groove is high, and a shocking external force is applied to the lens barrel. In this case, disengagement of the cam pin and damage to the cam pin and the cam groove hardly occur.
[0047]
In particular, as for the external force applied from the front of the lens barrel, only the protective frame retreats and absorbs the external force, so that the interlocking mechanism between the cam pin and the cam groove of the moving frame is hardly affected by the external force. It becomes a zoom lens barrel with excellent properties.
[Brief description of the drawings]
FIG. 1 is a perspective view of a camera provided with a zoom lens barrel according to the present invention.
FIG. 2 is a simplified sectional view of a zoom lens barrel showing an embodiment of the present invention.
FIG. 3 is a sectional view similar to FIG. 2, illustrating an operation when an external force is applied to the zoom lens barrel shown in FIG. 2;
FIG. 4 is a sectional view similar to FIG. 2, showing another embodiment.
FIG. 5 is a sectional view similar to FIG. 4, showing an operation when an external force is applied to the zoom lens barrel shown in FIG. 4;
6 is a sectional view similar to FIG. 4, showing an improved example of the zoom lens barrel shown in FIG. 4;
FIG. 7 is a sectional view similar to FIG. 6, showing an operation when an external force is applied to the zoom lens barrel shown in FIG. 6;
[Explanation of symbols]
11 zoom lens barrel 12 cam frame 12a cam groove 13 moving frame 13a cam pin 14 objective lens 15 protection frame 15a cam pin 16 coil spring 21 cam frames 21a, 21b cam groove 23 coil spring

Claims (2)

A zoom lens barrel including a cam frame that is driven to rotate and a moving frame provided with a cam pin that protrudes into a cam groove of the cam frame, and moves the moving frame in the optical axis direction in conjunction with the rotation of the cam frame. ,
A cam frame in which a wide cam groove is spirally formed,
A protective frame movably provided in the optical axis direction so as to cover the moving frame;
A cam pin provided on the protection frame so as to protrude into the cam groove,
A biasing member that applies a retreating force to the moving frame to apply the cam pin to one side groove surface of the cam groove, and applies an advancing force to the protection frame to press the cam pin against the other side groove surface of the cam groove. A zoom lens barrel. The zoom lens barrel according to claim 1,
A cam frame is formed in which two cam grooves are formed spirally with one cam groove being wider than the other cam groove,
A zoom lens barrel, wherein a cam pin of the moving frame is inserted into one cam groove of the cam frame, and a cam pin of the protection frame is inserted into the cam groove of the other cam frame.

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