JPWO2020003941A1 - Lens barrel and imaging device - Google Patents

Abstract

Provided are a lens barrel and an imaging device capable of smoothly moving a movable frame. The first principal shaft (68) and the first sub-axis (70) fixed to the fixed cylinder (12) and the cam cylinder (14) via the fourth lens group base holding frame (26A), and the fourth lens group (4th lens group). A fourth lens group movable holding frame (26B) that holds G4) and is movably supported in the direction of the optical axis (Z) by the first main axis (68) and the first sub-axis (70), and a fourth lens. The 4th lens group movable holding frame (26B) is provided with a balance weight (76) arranged on the group movable holding frame (26B), and the center of gravity of the 4th lens group (G4) is deviated to one end side. The holding and balance weight (76) is a lens barrel arranged on the other end side of the fourth lens group movable holding frame (26B). Further, it is an imaging device including a lens barrel.

Description

The present invention relates to a lens barrel and an imaging device, and in particular, a lens barrel and an imaging device in which optical members to be held are biased toward one end with respect to a movable frame that can move in the optical axis direction. Regarding.

Conventionally, there is an image pickup apparatus provided with a plurality of lens groups, and in such an image pickup apparatus, each frame member holding these lens groups is slidably held.

For example, in Patent Document 1 below, a position detection magnet for detecting a position in the XY directions orthogonal to the optical axis with high accuracy is provided, and a weight that balances the weight balance with the position detection magnet is arranged. The autofocus camera to be used is described.

Japanese Unexamined Patent Publication No. 2016-48383

In order to stabilize the movement of the movable frame in which the optical member is held, it is necessary to lengthen the sleeve portion of the movable frame. However, when the sleeve portion is lengthened, it is difficult to bring the adjacent optical members close to each other. Therefore, a structure is adopted in which the optical member is biased toward one end side along the optical axis direction from the sleeve portion of the movable frame. However, in the movable frame in which such an optical member is held on one end side, one end side of the movable frame bends downward, and when it is moved along the optical axis direction, it does not move parallel to the main axis and the sub axis. , Friction may occur between the main shaft or the sub-shaft and the sleeve portion, and vibration may be generated.

The present invention has been made in view of such circumstances, and provides a lens barrel and an imaging device capable of smoothly moving a movable frame.

In order to achieve the object of the present invention, the lens barrel according to the present invention holds a fixed frame, a first spindle and a first sub-axis fixed to the fixed frame, and an optical member, and holds the first spindle and the first spindle. A first movable frame supported by a sub-axis so as to be movable in the optical axis direction of the optical member and a balance weight arranged on the first movable frame are provided, and the first movable frame has an optical member on one end side. The center of gravity is biased and held, and the balance weight is arranged on the other end side of the first movable frame.

According to the present invention, even if the optical member provided on the first movable frame is held with the center of gravity biased toward one end side of the first movable frame, a balance weight is provided on the other end side. The position of the center of gravity of the first movable frame can be moved to the other end side. Therefore, when the first movable frame is supported and moved by the first main shaft and the first sub-axis, it is possible to prevent the first movable frame from becoming slanted due to the bias of the center of gravity. Therefore, the friction generated between the first movable frame and the first spindle can be reduced, and the first movable frame can be smoothly moved without generating vibration.

In one aspect of the present invention, it is preferable that the center of gravity of the first movable frame on which the balance weight is arranged is moved to the inside of the sleeve portion guided by the balance weight to the first spindle.

According to this aspect, by setting the center of gravity of the first movable frame to the inside of the sleeve portion where the first movable frame is guided by the first main shaft, the weight-bearing portion can be inside the sleeve. Therefore, the first movable frame can be stably moved while being supported by the first main shaft and the first sub-shaft.

In one aspect of the present invention, it is preferable that the first movable frame is a resin cylinder having a cavity on the other end side, and the balance weight is a rigid body arranged on the other end side of the cylinder. ..

According to this aspect, the rigidity of the first movable frame can be increased by making the balance weight a rigid body. By increasing the rigidity, the natural frequency of the first movable frame can be increased, and it is possible to prevent the shaking of the first movable frame from being increased due to resonance. In the present invention, the rigid body means a material having a small dimensional change when a force is applied, and at least a material having a higher rigidity than the resin forming the first movable frame is used.

In one aspect of the present invention, it is preferable that the balance weight has a ring shape and is arranged on the other end side of the cylinder.

According to this aspect, by forming the balance weight into a ring shape, the rigidity of the first movable frame can be increased, and since the balance weight has a ring shape, the weight is evenly weighted in the direction perpendicular to the optical axis direction. Can be applied. Therefore, since it is possible to prevent the center of gravity from deviating from the center position in the optical axis direction, the first movable frame can be moved in parallel with the optical axis direction, and the first movable frame can be moved smoothly. it can.

In one aspect of the present invention, it is preferable that the balance weight is composed of a plurality of members and is arranged at intervals along the outer diameter of the cylinder.

This aspect shows another embodiment of the balance weight, and by arranging a plurality of balance weights along the outer diameter of the cylinder, the position of the center of gravity can be changed as in the case of the ring shape. It can be moved to the end side and the rigidity of the first movable frame can be increased.

One aspect of the present invention holds a second main shaft and a second sub-axis fixed to a fixed frame and an optical member, and is supported by the second main shaft and the second sub-shaft so as to be movable in the optical axis direction of the optical member. It is preferable that the second movable frame is provided with a second movable frame, and a part of the second movable frame can enter the cavity of the first movable frame.

According to this aspect, the second movable frame holding the optical member can enter the cavity provided by arranging the optical member provided in the first movable frame with the center of gravity deviated to one end side. .. As a result, the optical member provided on the second movable frame and the optical member provided on the first movable frame can be brought close to each other.

One aspect of the present invention includes a first drive unit for moving the first movable frame and a second drive unit for moving the second movable frame, and the first drive unit is a moving coil type voice coil motor. The second drive unit is preferably a moving magnet type voice coil motor.

According to this aspect, by using the moving coil type voice coil motor as the first drive unit, the coil is lighter than the magnet, so that the first movable frame can be smoothly moved. Further, by using a moving magnet type voice coil motor as the second drive unit, the lens barrel can be miniaturized.

In one aspect of the present invention, the fixed frame comprises a first frame body in which the first main shaft and the first sub shaft are fixed, and a second frame body in which the second main shaft and the second sub shaft are fixed. Is preferable.

According to this aspect, by forming the fixed frame from the first frame body and the second frame body, the first movable frame and the second movable frame are provided to the first frame body and the second frame body, respectively. Since it can be moved, the moving distances of the first movable frame and the second movable frame can be adjusted.

In one aspect of the present invention, the balance weight is preferably made of brass.

In this aspect, the material of the balance weight used is limited, and by using brass as the material of the balance weight, the position of the center of gravity of the first movable frame can be changed and the rigidity of the first movable frame can be increased. Can be done.

In one aspect of the present invention, it is preferable that the natural frequency of the first movable frame provided with the balance weight is larger than the operating frequency of the voice coil motor of the first drive unit.

According to this aspect, by making the natural frequency of the first movable frame larger than the frequency used by the voice coil motor of the first drive unit, the vibration caused by the movement of the first movable frame and the vibration caused by the voice coil motor can be obtained. It is possible to prevent the vibration from becoming large due to resonance. Therefore, the position accuracy of moving the first movable frame by the voice coil motor can be improved. In addition, the generation of abnormal noise can be suppressed.

In one aspect of the present invention, the natural frequency is preferably larger than 300 Hz.

In this aspect, the numerical value of the natural frequency is defined, and the natural frequency of the first movable frame can be made different from the operating frequency of the voice coil motor by making it larger than 300 Hz. Therefore, it is possible to prevent the vibration of the first movable frame from becoming large due to the resonance between the vibration caused by the voice coil motor and the vibration caused by the movement of the first movable frame.

In order to achieve the object of the present invention, the image pickup apparatus according to the present invention includes the lens barrel described above.

According to the present invention, by providing the lens barrel described above, the optical member can be smoothly moved, and the position accuracy of the optical member can be satisfactorily determined.

According to the lens barrel of the present invention, by holding the optical member on one end side, a balance weight is arranged on the other end side with respect to the first movable frame whose center of gravity is biased toward one end side. 1 The center of gravity of the movable frame can be moved to the other end side. Therefore, when the first movable frame is moved, the weight of the optical member can prevent the first movable frame from swinging, and the first movable frame can be stably moved along the first main shaft and the first sub-axis. Can be done.

It is a side sectional view which shows the schematic structure of the inside of a lens barrel at a wide-angle end. It is a top view which shows the schematic structure of the inside of a lens barrel at a wide-angle end. It is a figure which shows the moving state of each lens group at the time of a zoom operation. It is a side sectional view which shows the schematic structure of the inside of a lens barrel at a telephoto end. It is a cross-sectional view of 5-5 of FIG. 1 and FIG. It is a 6-6 sectional view of FIG. 1 and FIG. It is a figure which shows the position of the center of gravity of the 4th lens group movable frame by the presence or absence of a balance weight. It is a figure which shows the modification of the balance weight. It is a figure which shows the other modification of the balance weight. It is a block diagram which shows the electrical structure of an interchangeable lens. It is a perspective view which looked at the camera system diagonally from the front. It is a rear view of a camera body.

Hereinafter, the lens barrel and the image pickup apparatus according to the present invention will be described with reference to the accompanying drawings.

[Structure of lens barrel]
Here, a case where the lens barrel of the present embodiment is applied to an interchangeable lens of an interchangeable lens camera will be described as an example. FIG. 1 is a side sectional view showing a schematic configuration of the inside of the lens barrel at the wide-angle end, and FIG. 2 is a plan sectional view showing a schematic configuration of the inside of the lens barrel at the wide-angle end.

The interchangeable lens 1 of the present embodiment is a so-called zoom lens, and is mainly composed of a lens barrel body 10 to which the lens is assembled and an exterior body 100 that covers the outer periphery of the lens barrel body 10. By rotating the zoom ring 7 provided on the outer peripheral portion of the exterior body 100, the focal length is continuously changed. The zoom ring 7 is connected to the cam cylinder 14 by a connecting member (not shown), and by rotating the zoom ring 7, the cam cylinder 14 rotates and the focal length is changed.

Further, the interchangeable lens 1 of the present embodiment has a manual focus adjustment function, and the focus can be manually adjusted by rotating the focus ring 8 provided on the outer peripheral portion thereof. Further, the interchangeable lens 1 of the present embodiment has an aperture setting function manually, and the aperture can be manually set by rotating the aperture ring 9 provided on the outer peripheral portion thereof. The zoom ring 7, the focus ring 8, and the aperture ring 9 are examples of a plurality of operation rings.

≪Main body of lens barrel≫
As shown in FIGS. 1 and 2, the lens barrel main body 10 has a fixed cylinder 12 and a cam cylinder 14. The cam cylinder 14 is fitted to the inner peripheral portion of the fixed cylinder 12, and the inner peripheral portion of the fixed cylinder 12 is rotatably held in the circumferential direction. The fixed cylinder 12 is an example of a fixed frame.

The fixed cylinder 12 has a mount 16 at its base end (end on the image plane side). The mount 16 is composed of a so-called bayonet mount. The mount 16 is attached to the base end portion of the fixing cylinder 12 by a plurality of mounting fixing screws 18.

As shown in FIGS. 1 and 2, the fixed cylinder 12 is configured such that the base end portion has the smallest outer diameter. The outer diameter of the mount 16 is equal to or less than the outer diameter of the base end portion of the fixed cylinder 12. More specifically, the outer diameter of the flange portion 16A having the largest outer diameter is set to be equal to or less than the outer diameter of the base end portion of the fixed cylinder 12. In the present embodiment, the outer diameter of the flange portion 16A is the same as the outer diameter of the base end portion of the fixed cylinder 12.

<Lens configuration>
A plurality of lenses are arranged inside the fixed cylinder 12. Specifically, the first lens group G1, the second lens group G2, the third lens group G3, the fourth lens group G4, and the fifth lens group G5 are arranged in order from the object side along the optical axis Z. .. Each lens group is composed of at least one lens. The first lens group G1, the second lens group G2, the third lens group G3, the fourth lens group G4, and the fifth lens group G5 are examples of optical members.

Further, a diaphragm St is arranged inside the fixed cylinder 12. The aperture St is arranged between the first lens group G1 and the second lens group G2.

FIG. 3 is a diagram showing a moving state of each lens group when the zoom operation is performed. FIG. 4 is a side sectional view showing a schematic configuration of the inside of the lens barrel at the telephoto end. In FIG. 3, (A) shows the lens arrangement at the wide-angle end, and (B) shows the lens arrangement at the telephoto end.

As shown in FIG. 3, the first lens group G1 to the fourth lens group G4 are lens groups that move with respect to the image plane Sim by the zoom operation. The fifth lens group G5 is a lens group fixed with respect to the image plane Sim by the zoom operation. The first lens group G1 moves along the movement locus AL1 by the zoom operation, and the second lens group G2 moves along the movement locus AL2 by the zoom operation. Further, the third lens group G3 moves along the movement locus AL3 by the zoom operation, and the fourth lens group G4 moves along the movement locus AL4 by the zoom operation. The aperture St moves integrally with the second lens group G2.

As shown in FIG. 3, the third lens group G3 is composed of a third lens group front group G3a and a third lens group rear group G3b. The third lens group front group G3a is a lens group for correcting curvature of field. The third lens group front group G3a is a lens group that can move independently of other lens groups. When correcting the curvature of field, the front group G3a of the third lens group is moved along the optical axis Z.

The fourth lens group G4 is a lens group for focusing adjustment. The fourth lens group G4 is a lens group that can move independently of other lens groups. When adjusting the focus, the fourth lens group G4 is moved along the optical axis Z.

<Holding structure of each lens group>
[First lens group]
As shown in FIGS. 1 and 2, the first lens group G1 is held by the first lens group holding frame 20 and arranged in the fixed cylinder 12.

The first lens group holding frame 20 is provided with three first lens group driving cam pins 32 on the outer peripheral portion thereof. The three first lens group driving cam pins 32 are arranged at equal intervals in the circumferential direction. Each of the first lens group driving cam pins 32 is fitted into the first lens group driving cam groove 14A provided in the cam cylinder 14 and the first lens group driving straight groove provided in the fixed cylinder 12, respectively.

With the above configuration, the first lens group G1 is held in the fixed cylinder 12. Further, when the cam cylinder 14 is rotated, the first lens group G1 moves in the fixed cylinder 12 along the optical axis Z.

[Second lens group]
As shown in FIGS. 1 and 2, the second lens group G2 is held by the second lens group holding frame 22 and arranged in the fixed cylinder 12.

The second lens group holding frame 22 is provided with three second lens group driving cam pins 34 on the outer peripheral portion thereof. The three second lens group driving cam pins 34 are arranged at equal intervals in the circumferential direction. Each of the second lens group driving cam pins 34 is fitted into the second lens group driving cam groove 14B provided in the cam cylinder 14 and the second lens group driving straight groove provided in the fixed cylinder 12, respectively.

With the above configuration, the second lens group G2 is held in the fixed cylinder 12. Further, when the cam cylinder 14 is rotated, the second lens group G2 moves in the fixed cylinder 12 along the optical axis Z.

As shown in FIGS. 1 and 2, the diaphragm unit 30 constituting the diaphragm St is assembled to the second lens group holding frame 22. As a result, the diaphragm St is arranged in the fixed cylinder 12 and moves together with the second lens group G2.

[Third lens group]
As shown in FIGS. 1 and 2, the third lens group G3 is held by the third lens group holding frame 24 and arranged in the fixed cylinder 12.

The third lens group holding frame 24 includes a third lens group rear group holding frame 24A and a third lens group front group holding frame 24B held on the inner peripheral portion of the third lens group rear group holding frame 24A. Will be done. The third lens group front group holding frame 24B is movably held on the inner peripheral portion of the third lens group rear group holding frame 24A along the optical axis Z. The third lens group front group G3a is held by the third lens group front group holding frame 24B. The rear group G3b of the third lens group is held by the rear group holding frame 24A of the third lens group.

FIG. 5 is a 5-5 cross-sectional view of FIGS. 1 and 2.

As shown in FIG. 5, the third lens group rear group holding frame 24A is provided with three third lens group driving cam pins 36 on the outer peripheral portion thereof. The three third lens group driving cam pins 36 are arranged at equal intervals in the circumferential direction. Each third lens group driving cam pin 36 is fitted into the third lens group driving cam groove 14C provided in the cam cylinder 14 and the third lens group driving straight groove 12C provided in the fixed cylinder 12, respectively. ..

A second main shaft 48 and a second sub-shaft 50 are provided on the inner peripheral portion of the rear group holding frame 24A of the third lens group. The second main shaft 48 and the second sub-axis 50 are arranged at positions facing each other with the optical axis Z interposed therebetween (arranged at intervals of 180 ° in the circumferential direction), and are arranged along the optical axis Z, respectively.

The third lens group front group holding frame 24B is provided with the second main shaft 48 and the second sub shaft provided in the third lens group rear group holding frame 24A via the second main guide portion 52 and the second sub guide portion 54. It is slidably supported by 50. As a result, the third lens group front group holding frame 24B is movably supported along the optical axis Z at the inner peripheral portion of the third lens group rear group holding frame 24A. The third lens group rear group holding frame 24A is an example of the second frame body, and the third lens group front group holding frame 24B is an example of the second movable frame.

The third lens group front group holding frame 24B is driven by the second motor 56 to move the inner peripheral portion of the third lens group rear group holding frame 24A along the optical axis Z. The second motor 56 is composed of a moving magnet type voice coil motor. The third lens group front group holding frame 24B is provided with a plurality of magnets 56A and a plurality of inner yokes 56B of the voice coil motors constituting the second motor 56. Further, the rear group holding frame 24A of the third lens group is provided with a coil 56C of a voice coil motor constituting the second motor 56 and a plurality of outer yokes 56D. The second motor 56 is an example of the second drive unit.

With the above configuration, the third lens group G3 is held in the fixed cylinder 12. Further, when the cam cylinder 14 is rotated, the third lens group G3 moves along the optical axis Z in the fixed cylinder 12 (the third lens group front group G3a and the third lens group rear group G3b are integrally integrated. It moves along the optical axis Z in the fixed cylinder 12). Further, when the second motor 56 is driven, the third lens group front group G3a moves independently along the optical axis Z (the third lens group front group G3a independently moves along the optical axis Z). .). The curvature of field is corrected by moving the front group G3a of the third lens group independently.

[4th lens group]
As shown in FIGS. 1 and 2, the fourth lens group G4 is held by the fourth lens group holding frame 26 and arranged in the fixed cylinder 12. The fourth lens group holding frame 26 is composed of a fourth lens group base holding frame 26A and a fourth lens group movable holding frame 26B held on the inner peripheral portion of the fourth lens group base holding frame 26A. .. The fourth lens group movable holding frame 26B is movably supported on the inner peripheral portion of the fourth lens group base holding frame 26A along the optical axis Z. The fourth lens group G4 is held on the inner peripheral portion of the fourth lens group movable holding frame 26B.

FIG. 6 is a cross-sectional view taken along the line 6-6 of FIGS. 1 and 2.

As shown in FIG. 6, the fourth lens group base holding frame 26A is provided with three fourth lens group driving cam pins 38 on the outer peripheral portion thereof. The three fourth lens group driving cam pins 38 are arranged at equal intervals in the circumferential direction. Each of the fourth lens group driving cam pins 38 is fitted into the fourth lens group driving cam groove 14D provided in the cam cylinder 14 and the fourth lens group driving straight groove 12D provided in the fixed cylinder 12, respectively. ..

Further, the fourth lens group base holding frame 26A is provided with a first main shaft 68 and a first sub-shaft 70. The first main shaft 68 and the first sub-axis 70 are arranged at positions facing each other with the optical axis Z interposed therebetween (arranged at intervals of 180 ° in the circumferential direction), and are arranged along the optical axis Z, respectively.

The fourth lens group movable holding frame 26B is attached to the first main shaft 68 and the first sub shaft 70 provided in the fourth lens group base holding frame 26A via the first main guide portion 72 and the first sub guide portion 74. It is supported so that it can slide freely. As a result, the fourth lens group movable holding frame 26B is movably supported on the inner peripheral portion of the fourth lens group base holding frame 26A along the optical axis Z. The fourth lens group base holding frame 26A is an example of the first frame body, the fourth lens group movable holding frame 26B is an example of the first movable frame, and the first main guide portion 72 is an example of the sleeve portion. is there.

The fourth lens group movable holding frame 26B is driven by the first motor 58, which is a focus motor, and moves the inner peripheral portion of the fourth lens group base holding frame 26A along the optical axis Z. The first motor 58 is composed of a moving coil type voice coil motor. The fourth lens group movable holding frame 26B is provided with a plurality of coils 58A of the voice coil motors constituting the first motor 58. Further, the fourth lens group base holding frame 26A is provided with a plurality of magnets 58B, a plurality of inner yokes 58C, and a plurality of outer yokes 58D of the voice coil motor constituting the first motor 58. The first motor 58 is an example of the first drive unit.

With the above configuration, the fourth lens group G4 is held in the fixed cylinder 12. Further, when the cam cylinder 14 is rotated, the fourth lens group G4 moves in the fixed cylinder 12 along the optical axis Z. Further, when the first motor 58 is driven, the fourth lens group G4 independently moves along the optical axis Z. Focus adjustment is performed by moving the fourth lens group G4 independently.

The fourth lens group movable holding frame 26B is provided with a balance weight 76 at a position opposite to the fourth lens group G4 in the direction of the optical axis Z. The balance weight 76 can move the positions of the centers of gravity of the fourth lens group movable holding frame 26B and the fourth lens group G4 to the tip side (object side). The configuration of the balance weight 76 will be described later.

[Fifth lens group]
As shown in FIGS. 1 and 2, the fifth lens group G5 is held by the fifth lens group holding frame 28 and arranged in the fixed cylinder 12. The fifth lens group holding frame 28 is attached to the fixing cylinder 12 by a plurality of fifth lens group fixing screws.

<Operation of each lens group>
The lens barrel body 10 is configured as described above.

When the cam cylinder 14 is rotated, the lens barrel body 10 causes the first lens group G1, the second lens group G2, the third lens group G3, and the fourth lens group G4 to move along the optical axis Z. This causes zooming.

Further, by driving the second motor 56, the lens barrel body 10 causes the third lens group front group G3a to move independently along the optical axis Z. The interchangeable lens 1 corrects curvature of field by independently moving the front group G3a of the third lens group.

Further, by driving the first motor 58, the fourth lens group G4 moves independently along the optical axis Z. The focus of the interchangeable lens 1 is adjusted by moving the fourth lens group G4 independently. The fourth lens group movable holding frame 26B is a tubular body that holds the fourth lens group G4 on one end side (image plane side) and has a cavity on the other end side (object side). A part of the third lens group rear group holding frame 24A and a part of the third lens group front group holding frame 24B holding the third lens group G3 are configured to be able to enter the cavity at the wide-angle end.

Further, the lens barrel body 10 moves the third lens group G3 in a plane orthogonal to the optical axis by rotating an optical axis adjustment pin (not shown). As a result, the optical axis Z is adjusted.

<Balance weight>
The balance weight 76 is arranged on the object side of the fourth lens group movable holding frame 26B. The balance weight 76 is provided to move the position of the center of gravity of the fourth lens group movable holding frame 26B that holds the fourth lens group G4 toward the object side. The balance weight 76 can be arranged by fitting the ring-shaped balance weight 76 on the object side of the tubular fourth lens group movable holding frame 26B.

FIG. 7 is a diagram showing the position of the center of gravity of the fourth lens group movable holding frame 26B depending on the presence or absence of the balance weight 76. In the figure, (A) is a diagram having no balance weight, and (B) is a diagram having a balance weight. As shown in FIG. 7A, the fourth lens group G4 is held on the image plane side (the other end side) of the fourth lens group movable holding frame 26B. The position of the center of gravity g of the fourth lens group movable holding frame 26B that holds the four lens group G4 is biased toward the image plane side (one end side). In such a case, when one end side of the fourth lens group movable holding frame 26B is tilted, the first main shaft 68 and the first main guide portion 72 are not parallel to each other, and when the fourth lens group movable holding frame 26B is moved. , Abnormal noise may occur.

On the other hand, as shown in FIG. 7B, by providing the balance weight 76, the position of the center of gravity g can be moved to the object side (the other end side). In particular, the position of the center of gravity g is lowered inside the first main guide portion 72 of the fourth lens group movable holding frame 26B guided by the first main shaft 68, that is, the first main guide portion 72 with respect to the optical axis Z. It is preferably within the range of the vertical line. By setting the inside of the first main guide portion 72, the fourth lens group movable holding frame 26B can be supported by the first main guide portion 72 and the first sub guide portion 74, so that the fourth lens group movable holding frame 26B can be smoothly held. The frame 26B can be moved.

FIG. 8 is a diagram showing another shape of the balance weight. As shown in FIG. 6, the balance weight is not limited to the ring shape along the outer diameter of the cylinder of the fourth lens group movable holding frame 26B, and as shown in FIG. 8, a plurality of members 78a, 78b, 78c. , 78d, and the plurality of members 78a, 78b, 78c, 78d may be arranged at intervals along the outer diameter of the cylinder of the fourth lens group movable holding frame 26B. As shown in FIG. 8, even if a plurality of members 78a, 78b, 78c, and 78d are arranged at intervals, the position of the center of gravity of the fourth lens group movable holding frame 26B can be moved to the object side. .. When the balance weight 78 composed of a plurality of members 78a, 78b, 78c, and 78d is arranged, it is preferable to arrange the balance weight 78 symmetrically with respect to the center of the fourth lens group G4. By arranging them symmetrically, it is possible to prevent the center of gravity of the fourth lens group movable holding frame 26B from being biased with respect to the vertical direction of the optical axis Z. Therefore, the fourth lens group movable holding frame 26B can be smoothly moved.

When the balance weight 78 composed of a plurality of members is arranged on the fourth lens group movable holding frame 26B, for example, a groove is provided in the fourth lens group movable holding frame 26B, and the members 78a, 78b, 78c, and 78d are formed. It can be arranged by fitting it with the groove and adhering it with an adhesive.

FIG. 9 is a diagram showing the shapes of other balance weights. As shown in FIG. 9, the balance weight may be a C-shaped balance weight 80. As the C-shaped balance weight, the position of the center of gravity g of the fourth lens group movable holding frame 26B can be moved to one end side, and the rigidity can be increased.

Since the fourth lens group G4 is biased toward one end side of the fourth lens group movable holding frame 26B, the fourth lens group G4 does not contribute to the rigidity of the fourth lens group movable holding frame 26B. Therefore, the rigidity of the 4th lens group movable holding frame 26B becomes low, and when the rigidity becomes low, the natural frequency of the 4th lens group movable holding frame 26B becomes low. The shaking of the group movable holding frame 26B becomes large. In the present embodiment, by disposing the balance weights 76, 78, 80, it is possible to impart rigidity to the fourth lens group movable holding frame 26B.

In order to increase the rigidity of the fourth lens group movable holding frame 26B, it is preferable that the materials of the balance weights 76, 78, and 80 are rigid bodies. Here, high rigidity means that the dimensional change is small when a force is applied, and as the rigid body, a material having higher rigidity than the material forming the fourth lens group movable holding frame 26B can be used. it can. As a material for forming the fourth lens group movable holding frame 26B, resin can be used, and for example, polycarbonate can be used. As the material used for the balance weights 76, 78, 80, for example, brass can be used. Further, by adopting a ring shape as the shape, the rigidity of the fourth lens group movable holding frame 26B can be further increased.

By increasing the rigidity, the natural frequency of the fourth lens group movable holding frame 26B can be increased. Specifically, it is preferable that the frequency is higher than the operating frequency of the voice coil motor of the first motor 58, and resonance can be prevented by increasing the operating frequency. By preventing resonance, it is possible to prevent deterioration of the position accuracy of movement of the fourth lens group movable holding frame 26B and generation of abnormal noise, and to stably move the fourth lens group movable holding frame 26B. it can.

The natural frequency of the fourth lens group movable holding frame 26B is preferably, for example, a natural frequency higher than 300 kHz. By making the natural frequency higher than 300 kHz, it is possible to prevent resonance with the voice coil motor when the fourth lens group movable holding frame 26B moves.

[Electrical configuration of interchangeable lens]
FIG. 10 is a block diagram showing the electrical configuration of the interchangeable lens.

The interchangeable lens 1 includes a third lens group front group driving unit 210 for driving the third lens group front group G3a, a third lens group front group position detecting unit 212 for detecting the position of the third lens group front group G3a, and a fourth lens group. The temperature inside the fourth lens group drive unit 214 that drives the lens group G4, the fourth lens group position detection unit 216 that detects the position of the fourth lens group G4, the aperture drive unit 218 that drives the aperture St, and the interchangeable lens 1 Overall control of the overall operation of the temperature detection unit 220 to detect, the focus operation detection unit 222 to detect the focus operation, the zoom setting detection unit 224 to detect the zoom operation, the aperture setting detection unit 226 to detect the aperture operation, and the interchangeable lens 1. The lens control unit 228 is provided.

The third lens group front group drive unit 210 includes a second motor 56 and a drive circuit thereof. The third lens group front group driving unit 210 drives the second motor 56 in response to a command from the lens control unit 228 to move the third lens group front group G3a along the optical axis Z.

The third lens group front group position detection unit 212 includes a position detection sensor (not shown). The position detection sensor is composed of, for example, a magnetic sensor such as a Hall element or a magneto resistive sensor. The third lens group front group position detection unit 212 detects the position of the third lens group front group G3a with the position detection sensor, and outputs the detection result to the lens control unit 228. The position of the third lens group front group G3a is the position with respect to the third lens group rear group G3b, and is the position within the third lens group rear group holding frame 24A.

The fourth lens group drive unit 214 includes a first motor 58 and a drive circuit thereof. The fourth lens group driving unit 214 drives the first motor 58 in response to a command from the lens control unit 228 to move the fourth lens group G4 along the optical axis Z.

The fourth lens group position detection unit 216 includes a position detection sensor (not shown). The position detection sensor is composed of, for example, a magnetic sensor such as a Hall element or a magnetoresistive effect element. The fourth lens group position detection unit 216 detects the position of the fourth lens group G4 with the position sensor, and outputs the detection result to the lens control unit 228. The position of the fourth lens group G4 is a position within the fourth lens group holding frame 26.

The diaphragm drive unit 218 includes a diaphragm motor and a drive circuit thereof. A diaphragm motor (not shown) is provided in the diaphragm unit 30. The aperture drive unit 218 drives the aperture motor to open and close the aperture St in response to a command from the lens control unit 228.

The temperature detection unit 220 includes a temperature sensor (not shown). The temperature sensor is provided in, for example, the diaphragm unit 30. The temperature detection unit 220 detects the temperature inside the interchangeable lens 1 with a temperature sensor, and outputs the detection result to the lens control unit 228.

The focus operation detection unit 222 detects the amount of rotation operation of the focus ring 8 and outputs the detection result to the lens control unit 228. The lens control unit 228 detects the focus operation amount based on the output from the focus operation detection unit 222.

The zoom setting detection unit 224 detects the set position of the zoom ring 7 and outputs the detection result to the lens control unit 228. The lens control unit 228 detects the zoom setting value (focal length) based on the output from the zoom setting detection unit 224.

The aperture setting detection unit 226 detects the set position of the aperture ring 9 and outputs the detection result to the lens control unit 228. The lens control unit 228 detects the aperture setting value (aperture value) based on the output from the aperture setting detection unit 226.

The lens control unit 228 controls the operation of each unit based on the operations of the focus ring 8, the zoom ring 7, and the aperture ring 9. Specifically, when the manual focus is set, the fourth lens group driving unit 214 is driven and the fourth lens group G4 is moved based on the rotation operation amount of the focus ring 8. Further, based on the setting of the zoom ring 7, the third lens group front group driving unit 210 and the fourth lens group driving unit 214 are driven, and the third lens group front group G3a and the fourth lens group G4 are moved to predetermined positions. Let me. Further, based on the setting of the aperture ring 9, the aperture drive unit 218 is driven to set the aperture St to a predetermined aperture amount (aperture value).

Further, the lens control unit 228 controls the operation of each unit in response to a command from the camera to which the interchangeable lens 1 is mounted. For example, based on the autofocus information from the camera, the fourth lens group driving unit 214 is driven to move the fourth lens group G4 to a predetermined position. Further, based on the aperture setting information from the camera, the aperture drive unit 218 is driven to set the aperture St to a predetermined aperture amount.

The lens control unit 228 communicates with the camera control unit 230 of the camera and receives a drive command of each unit from the camera control unit 230. Further, zoom setting information, aperture setting information, focus position information, and the like are transmitted to the camera control unit 230. Communication between the lens control unit 228 and the camera control unit 230 is performed via the terminal 16B provided on the mount 16.

Further, the lens control unit 228 drives the third lens group front group drive unit 210 based on the temperature detected by the temperature detection unit 220, and moves the third lens group front group G3a to a predetermined position.

The lens control unit 228 is composed of, for example, a computer equipped with a CPU (CPU: Central Processing Unit), a ROM (ROM: Read Only Memory), and a RAM (RAM: Random Access Memory), and executes a predetermined program. , Realize various control functions.

[Configuration of imaging device]
Next, an image pickup apparatus having the lens barrel of the present embodiment will be described. 11 and 12 are external views showing a configuration example of a camera system using the lens barrel of the present embodiment as an example of the image pickup apparatus. FIG. 11 is a perspective view of the camera system viewed diagonally from the front, and FIG. 12 is a rear view of the camera body.

As shown in FIG. 11, the camera system 110 is a mirrorless digital single-lens camera or a digital single-lens reflex camera composed of an interchangeable lens 1 and a camera body 150 to which the interchangeable lens 1 can be attached and detached. Further, the imaging device is not limited to the camera systems shown in FIGS. 11 and 12, and it goes without saying that the image pickup device may be a mirrorless digital single-lens camera or a digital single-lens reflex camera in which the lens and the camera body are integrally configured. ..

A main body mount 160 to which the interchangeable lens 1 is mounted, a finder window 120 of an optical finder, and the like are provided on the front surface of the camera main body 150, and a shutter release button 122, a shutter speed dial 123, and the like are mainly provided on the upper surface of the camera main body 150. An exposure compensation dial 124, a power lever 125, and a built-in flash 130 are provided.

Further, as shown in FIG. 12, the back surface of the camera body 150 is mainly provided with a monitor 116, an eyepiece 126 of an optical finder, a MENU and an OK key 127, a cross key 128, a play button 129, and the like.

The monitor 116 functions as a display unit that displays a live view image in the imaging mode, reproduces and displays the image captured in the playback mode, and displays various menu screens. The MENU and OK key 127 are operation keys that have both a function as a menu button for issuing a command to display a menu on the screen of the monitor 116 and a function as an OK button for instructing confirmation and execution of selected contents. Is. The cross key 128 is an operation unit for inputting instructions in four directions of up, down, left, and right, and functions as a button for selecting an item from the menu screen or instructing selection of various setting items from each menu. In addition, the up and down keys of the cross key 128 function as a zoom switch during imaging or a playback zoom switch in playback mode, and the left and right keys are frame advance (forward and reverse direction) buttons in playback mode. Functions as. The playback button 129 is a button for switching to a playback mode in which the captured still image or moving image is displayed on the monitor 116.

By using the lens barrel of the present embodiment as an interchangeable lens in such a camera system, in order to adjust the focus, when the fourth lens group G4 is moved, the first main axis 68 and the first sub-axis 70 are used. The fourth lens group movable holding frame 26B can be moved in parallel. Therefore, the fourth lens group movable holding frame 26B can be stably moved.

1 Interchangeable lens 7 Zoom ring 8 Focus ring 9 Aperture ring 10 Lens barrel body 12 Fixed cylinder 12C Straight groove for driving the 3rd lens group 12D Straight groove for driving the 4th lens group 14 Cam cylinder 14A Cam groove for driving the 1st lens group 14B 2nd lens group drive cam groove 14C 3rd lens group drive cam groove 14D 4th lens group drive cam groove 16 Mount 16A Flange 16B terminal 18 Mount fixing screw 20 1st lens group holding frame 22 2nd lens group Holding frame 24 3rd lens group holding frame 24A 3rd lens group rear group holding frame 24B 3rd lens group front group holding frame 26 4th lens group holding frame 26A 4th lens group base holding frame 26B 4th lens group movable holding frame 28 5th lens group holding frame 30 Aperture unit 32 1st lens group driving cam pin 34 2nd lens group driving cam pin 36 3rd lens group driving cam pin 38 4th lens group driving cam pin 48 2nd main shaft 50 2nd sub Shaft 52 2nd main guide 54 2nd sub guide 56 2nd motor 56A Magnet 56B Inner yoke 56C Coil 56D Outer yoke 58 1st motor 58A Coil 58B Magnet 58C Inner yoke 58D Outer yoke 68 1st main shaft 70 1st sub shaft 72 1st main guide part 74 1st sub guide part 76 Balance weight 78 Balance weight 78a, 78b, 78c, 78d Member 80 Balance weight 100 Exterior 110 Camera system 116 Monitor 120 Finder window 122 Shutter release button 123 Shutter speed dial 124 Exposed Correction dial 125 Power lever 126 Eyepiece 127 MENU and OK key 128 Cross key 129 Play button 130 Built-in flash 150 Camera body 160 Body mount 210 3rd lens group front group drive unit 212 3rd lens group front group position detection unit 214 4 Lens group drive unit 216 4th lens group position detection unit 218 Aperture drive unit 220 Temperature detection unit 222 Focus operation detection unit 224 Zoom setting detection unit 226 Aperture setting detection unit 228 Lens control unit 230 Camera control unit AL1 First lens by zooming Group movement locus AL2 Zoom movement locus of the second lens group AL3 Zoom movement locus of the third lens group AL4 Zoom movement locus of the fourth lens group G1 First lens group G2 Second lens group G3 Third lens group G3a In front of the 3rd lens group Group G3b 3rd lens group Rear group G4 4th lens group G5 5th lens group g Center of gravity Sim Image plane St Aperture

Claims (12)

Fixed frame and
The first spindle and the first sub-shaft fixed to the fixed frame,
A first movable frame that holds the optical member and is movably supported in the optical axis direction of the optical member by the first main shaft and the first sub-axis.
A balance weight arranged on the first movable frame is provided.
The first movable frame holds the optical member with its center of gravity deviated toward one end side.
The balance weight is arranged on the other end side of the first movable frame.
Lens barrel. The center of gravity of the first movable frame on which the balance weight is arranged is moved to the inside of the sleeve portion guided by the balance weight to the first spindle.
The lens barrel according to claim 1. The first movable frame is a resin cylinder having a cavity on the other end side.
The balance weight is a rigid body arranged on the other end side of the tubular body.
The lens barrel according to claim 1 or 2. The balance weight has a ring shape and is arranged on the other end side of the cylinder.
The lens barrel according to claim 3. The balance weight is composed of a plurality of members and is arranged at intervals along the outer diameter of the cylinder.
The lens barrel according to claim 3. The second main shaft and the second sub-shaft fixed to the fixed frame,
It is provided with a second movable frame that holds the optical member and is movably supported in the optical axis direction of the optical member by the second main shaft and the second sub-axis.
In the second movable frame, a part of the second movable frame can enter the cavity of the first movable frame.
The lens barrel according to any one of claims 3 to 5. A first drive unit for moving the first movable frame and a second drive unit for moving the second movable frame are provided. The first drive unit is a moving coil type voice coil motor, and the first drive unit is a moving coil type voice coil motor. 2 The drive unit is a moving magnet type voice coil motor.
The lens barrel according to claim 6. The fixed frame includes a first frame body to which the first main shaft and the first sub shaft are fixed, and a second frame body to which the second main shaft and the second sub shaft are fixed.
The lens barrel according to claim 6 or 7. The balance weight is made of brass.
The lens barrel according to any one of claims 1 to 8. The natural frequency of the first movable frame provided with the balance weight is higher than the frequency used by the voice coil motor of the first drive unit.
The lens barrel according to claim 7. The natural frequency is greater than 300 Hz.
The lens barrel according to claim 10. An imaging device including the lens barrel according to any one of claims 1 to 11.

Images