JPH0868930A - Lens barrel - Google Patents

Abstract

PURPOSE: To provide a lens barrel which can be rotated by almost fixed rotational torque and at an almost fixed rotational speed by minimizing the fluctuation of pressing load by a spring occurring at a gap between lenses. CONSTITUTION: The arm 44 of a pressing means 38 is freely turnably supported on the outside circumferential side of a front-group lens 30 and a rear-group lens 34. The arm 44 energized so as to be unidirectionally turned by a torsion coil spring 46. Then, the lenses 30 and 34 are pressed in a direction that they are mutually close to near or in a direction that they are mutually separated. Thus, the occurrence of the playing of the lenses 30 and 34 is suppressed. Besides, the fluctuation of the load by the spring 46 is reduced by minimizing the turning angle of the arm 44 corresponding to the change of the gap between the lenses 30 and 34.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens barrel, and more particularly to a lens barrel in which a distance between a front lens group and a rear lens group, which is movably supported on an optical axis by rotation of a cam barrel, changes. .

[0002]

2. Description of the Related Art As shown in FIGS. 19 and 20, in the case of a lens barrel 3 in which the gap in the optical axis direction between the front lens group 1 and the rear lens group 2 changes when zooming or focusing is performed. The holding frames 4 and 5 of the lenses 1 and 2 are engaged with the moving barrel 6 and the like via the helicoid screw 4A and the cam pin 5A. In this case, a slight amount of backlash is generated in the helicoid screw 4A and the cam pin 5A of the respective holding frames 4 and 5 and the moving barrel 6 and the like, and the distance between the lenses 1 and 2 is displaced due to this backlash. Therefore, the lens 1 and the lens 2 may have an adverse effect such as flapping. In order to prevent this adverse effect, a coil spring 7 is provided between the holding frames 4 and 5, and the holding frame 4 is urged by the coil spring 7.
The helicoid screw 4 </ b> A and the cam pin 5 </ b> A of No. 5 are brought into contact with the engaging portion such as the moving barrel 6. As a result, the front lens group 1
The engagement backlash generated between the rear lens group 2 and the rear lens group 2 is eliminated.

[0003]

However, the front group laser
Distance L when lens 1 and rear lens group 2 approach each other
_min(See FIG. 19), the front lens group 1 and the rear lens group 2
The distance L when the two are separated from each other_maxIf the difference between
(Refer to FIG. 20), the coil spring 7 approaches the minimum usable length.
As the repulsive force of the coil spring 7 increases, the coil spring
The load fluctuation of No. 7 becomes large.

As a result, the fluctuation of the rotational torque of the lens barrel becomes large, so that when the lens barrel is rotated by the electromagnetic motor, the zoom change and the zoom speed become uneven.
Since the electromagnetic motor is selected based on the maximum value of the fluctuation range of the rotation torque, useless power is consumed except for the maximum rotation torque. On the other hand, if the spring constant is reduced in order to suppress the increase in the load of the coil spring 7 during the minimum use, the wire diameter of the coil spring 7 becomes thin and the free length becomes long, so that the work of incorporating the coil spring 7 becomes difficult. .

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a lens barrel capable of suppressing fluctuations in the load of a spring and fluctuations in the rotational torque of the lens barrel. To do.

[0006]

In order to achieve the above object, the present invention comprises a front lens group and a rear lens group, and a first follower and a rear lens group formed on a frame of the front lens group. A second follower formed on the frame of the lens is slidably engaged with the cam barrel so that the rotation of the cam barrel changes the distance between the front lens group and the rear lens group. In a lens barrel in which the front lens group and the rear lens group move along the optical axis, an arm member is swingably provided and is elastically biased in one direction by an elastic member. The front lens group and the rear lens group are engaged with the lens and the rear lens group to urge the front lens group and the rear lens group in a direction toward each other or in a direction away from each other.

[0007]

According to the present invention, the arm member of the pressing means is rotatably supported on the outer peripheral side of the front lens group and the rear lens group. The arm member is biased by a torsion coil spring so as to rotate in one direction, whereby the arm member presses the front lens group and the rear lens group toward each other or away from each other. Therefore, it is possible to suppress the backlash of the front lens group and the rear lens group with the pressing means having a simple structure.

Further, since the rotation angle of the arm member corresponding to the change in the distance between the front lens group and the rear lens group can be suppressed to a small value, the spring load fluctuation of the torsion coil spring can be suppressed to a small value.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the lens barrel according to the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is a sectional view showing a tele position of a lens barrel according to the present invention, and FIG. 2 is a perspective view showing an enlarged main part thereof. As shown in Figure 1,
The lens barrel 10 is provided in a casing 12, and the casing 12 is provided on the front surface of a camera (not shown). The rear end of the fixed barrel 14 of the lens barrel 10 is attached to the casing 12, and the helicoid screw 1 is attached to the inner circumference of the fixed barrel 14.
4A is formed, and the helicoid screw 14A is attached to the first moving barrel 1
6A helicoid screw formed on the rear end of the outer periphery of 6
Is engaged with. A motor (not shown) is connected to the first moving barrel 16 so as to be able to transmit a rotational force, and the driving of this motor causes the first moving barrel 16 to rotate and move in the optical axis direction.

A first rectilinear barrel 18 is rotatably supported in the first movable barrel 16, and the first rectilinear barrel 18 moves integrally with the first movable barrel 16 in the optical axis direction. In addition, the first moving barrel 1
A groove 16A is formed in the inner circumference of the member 6 in parallel with the optical axis direction, and the embedded pin 17 is engaged with the groove 16A via a cam groove 18A of the first rectilinear barrel 18. The embedded pin 17 is provided at the rear end portion of the outer periphery of the second moving barrel 20, and the second moving barrel 20 is
The movable barrel 16 is supported so as to be movable in the optical axis direction.

Therefore, the turning force of the first moving barrel 16 is transmitted to the second moving barrel 20 via the embedded pin 17, and the second moving barrel 20 is connected to the cam groove of the first rectilinear barrel 18 and the first moving barrel 16. It is regulated by the groove 16A and moves in the optical axis direction while rotating. A second straight-moving barrel 22 is rotatably supported in the second moving barrel 20, and the second straight-moving barrel 22 moves integrally with the second moving barrel 20 in the optical axis direction. A front lens group frame 24 is movably fitted between the second moving barrel 20 and the second rectilinear barrel 22. A helicoid screw 24A is formed on the rear end of the outer periphery of the front lens group frame 24, and the helicoid screw 24A is formed on the inner periphery of the second moving barrel 20.
Is engaged with. The rotation of the front lens group frame 24 is restricted by the second rectilinear barrel 22. Therefore, when the second moving barrel 20 rotates, it is restricted by the helicoid screw and the second rectilinear barrel 22, and the front lens group frame 24 moves in the optical axis direction.

The front lens group frame 24 is formed in a tubular shape, and a shutter block 26 is mounted in the front lens group frame 24. The shutter block 26 includes shutter blades 28.
Is provided, and the front lens group 3 is provided in front of the shutter blade 28.
0 is provided. A rear lens group frame 32 is disposed behind the shutter block 26, and the rear lens group frame 32 is provided.
A rear lens group 34 is attached inside.

A cam pin 34 is provided on the peripheral surface of the rear lens group frame 32.
(See FIG. 4) is provided, and the cam pin 34 serves as the second moving barrel 2
It is fitted in the 0 cam groove 20A. The rotation of the rear lens group frame 32 is restricted by the second rectilinear barrel 22. Further, a rod 36 is attached to the peripheral surface of the rear lens group frame 32, and the rod 36 is movably fitted in the shutter block 26.

As a result, the front lens group frame 24 moves in the optical axis direction by the rotation of the second movable barrel 20, and at the same time, the rear lens group frame 32 is restricted by the cam pins 34 and the second rectilinear barrel 22.
Moves in the optical axis direction. In this case, zooming is performed by changing the distance between the front lens group frame 24 and the rear lens group frame 32. As shown in FIG. 2, openings 22A ... Are formed in the second linear cylinder 22, and cam pins 34 of the rear lens group frame 32 are fitted into the openings 22A. Also,
A guide groove 22B is formed in the second linear cylinder 22, and a pressing means 38 (see FIG. 3) is movably supported in the guide groove 22B. That is, as shown in FIG. 3, the pressing means 38 includes a support member 40, a rotary shaft 42, an arm 44, a torsion spring 46, and locking portions 48A and 48B (see FIG. 2).

The support member 40 is formed in an E-shaped cross section and is movably fitted in the guide groove 22B. Support member 4
A rotary shaft 42 is screwed to 0, and an arm 44 is rotatably supported on the rotary shaft 42. In addition, the rotary shaft 42
The coil portion of the torsion spring 46 is fitted in the. One end 46A of the torsion spring 46 is locked to the support member 40, and the other end 46B is locked to the arm 44 (see FIG. 2). As a result, the arm 44 is biased clockwise by the torsion spring 46.

As shown in FIG. 2, the pressing means 38 has locking portions 48A and 48B, and the locking portion 48A is provided on the inner circumference of the front lens group frame 24. The locking portion 48B is provided on the outer circumference of the rear lens group frame 32. Locking part 48A
The one end of the arm 44 comes into contact with, and the other end of the arm 44 comes into contact with the locking portion 48B. In this case, since the arm 44 is biased in the clockwise direction by the torsion spring 46, the arm 44 presses the locking portions 48A and 48B toward each other.

Accordingly, the helicoid screw 24A of the front lens group frame 24 is always in contact with the helicoid screw of the second moving barrel 20, and the cam pin 34 of the rear lens group frame 32 is in contact with the second moving barrel 20.
Always contact the cam surface of. As a result, the front lens group frame 2
4 and the second movable barrel 20 can be eliminated, and further, the rear group lens frame 32 and the second movable barrel 20 can be eliminated.

The operation of the first embodiment of the lens barrel according to the present invention constructed as above will be described. First, when the lens barrel 10 is housed (see FIG. 5), the rear lens group frame 3
The distance between the shutter block 26 and the shutter block 26 becomes L, and the arm 44 of the pressing means 38 is positioned substantially vertically. Next, when the lens barrel 10 is set to the wide position (see FIG. 6),
The maximum distance between the rear lens group frame 32 and the shutter block 26 is L _max . In this case, the rear lens group frame 32 moves in a direction away from the shutter block 26 and moves to the locking portion 48B.
Is located on the left side of the locking portion 48A. As a result, the arm 44 rotates counterclockwise against the biasing force of the torsion spring 46 and is tilted to the left.

Then, the lens barrel 10 is moved to the tele position (see FIG. 1).
(See), the distance between the rear lens group frame 32 and the shutter block 26 becomes the minimum L _min . In this case, the rear group lens frame 32 moves in a direction approaching the shutter block 26, and the locking portion 48B is located on the right side of the locking portion 48A. As a result, the arm 44 is rotated clockwise by the biasing force of the torsion spring 46 and is tilted to the right.

In FIGS. 1, 5 and 6, the arm 44 is urged clockwise by the torsion spring 46, so that the arm 44 presses the locking portions 48A and 48B toward each other. . Therefore, the front lens group frame 2
The helicoid screw 24A of No. 4 always contacts the helicoid screw of the second moving barrel 20, and the cam pin 34 of the rear lens group frame 32
Always contacts the cam surface of the second moving barrel 20. As a result, it is possible to eliminate play between the front lens group frame 24 and the second moving barrel 20, and further to eliminate play between the rear lens group frame 32 and the second moving barrel 20. Therefore, the gap between the front lens group 30 and the rear lens group 34 and the front lens group 30
Also, it is possible to prevent the rear lens group 34 from sagging.

On the other hand, the arm 44 is tilted to the left at the wide position in FIG. 6 and is tilted to the right at the tele position in FIG. In this case, the rotation angle of the arm 44 in the range from the wide position in FIG. 6 to the tele position in FIG. 1 can be set small, so that the spring load fluctuation is set small by adjusting the number of turns and the wire diameter of the torsion spring 46. can do. In the second embodiment and the first embodiment, the case where the support member 40 of the pressing means 38 is movably supported in the guide groove 22B of the second linear cylinder 22 has been described, but the present invention is not limited to this and is shown in FIGS. 7 and 8. The supporting member 40 of the pressing means 49 may be movably supported on the inner circumference of the front lens group frame 24 as in the second embodiment. As shown in FIGS. 7 and 8, the front lens group frame 24
A guide groove 50 is formed on the inner circumference of the support member 40, and the support member 40 is movably supported by the guide groove 50. Also in the case of the second embodiment, the same effect as that of the first embodiment can be obtained. Incidentally, FIG.
Further, in FIG. 8, the same members as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

In the third and second embodiments, the supporting member 40 of the pressing means 49 is connected to the guide groove 50 of the front lens group frame 24.
However, the present invention is not limited to this, and the support member 40 of the pressing means 52 is movably supported on the outer periphery of the rear lens group frame 32 as in the third embodiment shown in FIGS. 9 and 10. You may. As shown in FIGS. 9 and 10, a guide groove 54 is formed on the outer periphery of the rear lens group frame 32, and the support member 40 is movably supported by the guide groove 54. Also in the case of the third embodiment, the same effect as that of the first embodiment can be obtained. 9 and 10, the same members as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

In the fourth embodiment and the first to third embodiments, the end portion of the arm 44 formed in a flat plate shape is provided with the engaging portion 48A,
Although the case where the pin 55 is brought into contact with the block 48B has been described, the present invention is not limited to this, and even if the pin 55 is provided at the end of the arm 44 and the pin 55 is brought into contact with the block 57 as shown in FIGS. 11A and 11B. Good.

In the fifth embodiment and the first to third embodiments, the case where the arm 44 is movably supported by the second linear cylinder 22 or the like via the support member 40 has been described, but the present invention is not limited to this, and FIG. And the pressing means 5 of the fifth embodiment shown in FIG.
The end portion of the arm 58 may be rotatably supported on the inner circumference of the front lens group frame 24 as shown in FIG. Hereinafter, FIG. 12 and FIG.
The details of the fifth embodiment will be described in Section 3. 12 and 13, the same members as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

The end of the arm 58 of the pressing means 56 is rotatably supported on the inner circumference of the front lens group frame 24 via the rotary shaft 42. The rotary shaft 42 is screwed to the inner circumference of the front lens group frame 24, and a coil portion of a torsion spring 46 is fitted on the rotary shaft 42. One end of the torsion spring 46 is locked to the arm 58, and the other end is locked to the protrusion 60 (see FIG. 13) formed on the inner circumference of the front lens group frame 24.
As a result, the arm 58 is biased in the clockwise direction by the torsion spring 46.

The tip portion of the arm 58 abuts on the locking portion 48B, and the arm 58 presses the front lens group frame 24 and the rear lens group frame 32 toward each other by the biasing force of the torsion spring 46. Therefore, the helicoid screw 24A of the front lens group frame 24 is always in contact with the helicoid screw of the second moving barrel 20, and the cam pin 34 of the rear lens group frame 32 is in contact with the second moving barrel 20.
Always contact the cam surface of. As a result, the front lens group frame 2
4 and the second movable barrel 20 can be eliminated, and further, the rear group lens frame 32 and the second movable barrel 20 can be eliminated.

The operation of the lens barrel of the fifth embodiment according to the present invention constructed as above will be described. First, when the lens barrel 10 is housed (see FIG. 14), the distance between the rear lens group frame 32 and the shutter block 26 becomes L, and the arm 58 of the pressing means 56 is positioned substantially vertically. Next, when the lens barrel 10 is set to the wide position (see FIG. 15), the maximum distance between the rear lens group frame 32 and the shutter block 26 is L _max . In this case, the rear lens group frame 32 moves in a direction away from the shutter block 26 and moves toward the locking portion 4.
8B is located behind the rotary shaft 42. As a result, the arm 58 rotates counterclockwise against the biasing force of the torsion spring 46 and is tilted to the left.

Then, the lens barrel 10 is moved to the tele position (see FIG. 1).
6), the distance between the rear lens group frame 32 and the shutter block 26 becomes the minimum L _min . in this case,
The rear lens group frame 32 moves toward the shutter block 26, and the locking portion 48B is positioned in front of the rotation shaft 42. As a result, the arm 58 is rotated clockwise by the biasing force of the torsion spring 46 and is tilted rightward.

14 to 16, the arm 58 is urged clockwise by the torsion spring 46, so that the arm 58 presses the rotating shafts 42 and 48B toward each other. Therefore, the helicoid screw 24A of the front lens group frame 24 is always in contact with the helicoid screw of the second movable barrel 20, and the cam pin 34 of the rear lens group frame 32 is always in contact with the cam surface of the second movable barrel 20. As a result, it is possible to eliminate play between the front lens group frame 24 and the second moving barrel 20, and further to eliminate play between the rear lens group frame 32 and the second moving barrel 20. Therefore, the front lens group 30
It is possible to prevent a gap between the rear lens group 34 and the rear lens group 34 and a sagging of the front lens group 30 and the rear lens group 34.

On the other hand, the arm 58 is tilted to the left at the wide position in FIG. 15 and is tilted to the right at the tele position in FIG. In this case, from the wide position of FIG.
Since the rotation angle of the arm 58 in the range of the tele position can be set small, the spring load fluctuation can be reduced. In the sixth and fifth embodiments, the case where the distal end portion of the arm 58 is rotatably supported on the inner circumference of the front lens group frame 24 has been described, but the present invention is not limited to this, and the sixth embodiment shown in FIGS. As described above, the end portion of the arm 58 may be rotatably supported on the outer periphery of the rear group lens 34. In this case, the arm 58 is rotatably supported on the outer periphery of the rear group lens 34 via the rotary shaft 42 as in the fifth embodiment, and the arm 58 is rotated by the torsion spring 4.
It is urged clockwise at 6.

The tip of the arm 58 is in contact with the locking portion 48A of the front lens group frame 24 by the urging force of the torsion spring 46. As a result, the arm 58 presses the front lens group frame 24 and the rear lens group frame 32 toward each other by the biasing force of the torsion spring 46. Therefore, the sixth embodiment can obtain the same effect as the fifth embodiment. 17 and 18
The same members as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

In the seventh embodiment and the first to sixth embodiments, the pressing unit is used to form the front lens group 30 and the rear lens group 3.
Although the case where the front lens group 4 and the rear lens group 34 are pressed in the directions approaching each other has been described, the present invention is not limited to this. The same effect as can be obtained.

[0033]

As described above, according to the lens barrel of the present invention, the front lens group and the rear lens group are brought close to each other by the arm member biased by the torsion coil spring so as to rotate in one direction. Press in the directions to move or away from each other. Accordingly, it is possible to suppress the backlash of the front lens group and the rear lens group with the pressing unit having a simple structure.

Further, since the rotation angle of the arm member corresponding to the change in the distance between the front lens group and the rear lens group can be suppressed to a small value, the spring load fluctuation of the torsion coil spring can be suppressed to a small value. As a result, the lens barrel can be rotated with a substantially constant rotation torque. Therefore, when the lens barrel is rotated by the electromagnetic motor, it is possible to stabilize the zoom speed or save power.

[Brief description of drawings]

FIG. 1 is a sectional view showing a telephoto state of a lens barrel according to the present invention.

FIG. 2 is an enlarged perspective view showing a main part of a lens barrel according to the present invention.

FIG. 3 is a perspective view showing pressing means used in the lens barrel according to the present invention.

FIG. 4 is a view on arrow AA of FIG.

FIG. 5 is a sectional view showing a housed state of the lens barrel according to the present invention.

FIG. 6 is a sectional view showing a wide state of the lens barrel according to the present invention.

FIG. 7 is an enlarged perspective view of a main part of a second embodiment of the lens barrel according to the present invention.

FIG. 8 is a view on arrow BB in FIG.

FIG. 9 is an enlarged perspective view showing a main part of a third embodiment of the lens barrel according to the present invention.

FIG. 10 is a view on arrow CC of FIG.

11 (A) is a front view showing a pressing means used in Embodiment 4 of the lens barrel, and FIG. 11 (B) is a plan view thereof.

FIG. 12 is a perspective view showing an enlarged main part of a fifth embodiment of the lens barrel according to the present invention.

FIG. 13 is a view on arrow D-D of FIG. 12.

FIG. 14 is a sectional view showing a housed state of a lens barrel according to a fifth embodiment of the present invention.

FIG. 15 is a sectional view showing a wide-angle state of Embodiment 5 of the lens barrel according to the present invention.

FIG. 16 is a sectional view showing a telephoto state of Example 5 of the lens barrel according to the present invention.

FIG. 17 is a perspective view showing an enlarged main part of a sixth embodiment of the lens barrel according to the present invention.

FIG. 18 is a view on arrow EE in FIG.

FIG. 19 is a sectional view showing a conventional lens barrel in a telephoto state.

FIG. 20 is a cross-sectional view showing a wide state of a conventional lens barrel.

[Explanation of symbols]

 10 ... Lens barrel 30 ... Front group lens 34 ... Rear group lens 38 ... Pressing means 44, 58 ... Arm (arm member) 46 ... Torsion coil spring

Claims (1)

[Claims] 1. A cam barrel comprising a front lens group and a rear lens group, wherein a first follower formed on the frame body of the front group lens and a second follower formed on the frame body of the rear group lens are cam cylinders. And the front lens group and the rear lens group move along the optical axis so that the distance between the front lens group and the rear lens group is changed by the rotation of the cam barrel. In the lens barrel, an arm member is swingably provided and is urged to rotate in one direction by an elastic member, and the arm member engages with the front group lens and the rear group lens to form the front group lens and A lens barrel, wherein the rear group lenses are urged toward each other or away from each other.