JPH01107223A - Focus adjusting mechanism for zoom lens - Google Patents

Abstract

PURPOSE:To facilitate initial adjustment for focal length by moving lens groups in the direction of the optical axis only by rotating a focus adjusting pin. CONSTITUTION:This mechanism consists of a driving member 22 which is associated operatively with the forward/backward movement of a moving lens barrel 4 and the focus adjusting pin 7 having a support pin 7e and an eccentric pin 7a whose center is eccentric with the center of the support pin 7e. When the support pin 7e which is associated with the driving member 22 is rotated, the eccentric pin 7a swivels around the center of the support pin 7e. The moving lens 2 is associated with the eccentric pin 7a, so the optical-axis directional position of the moving lens 2 changes with the coupling position between the eccentric pin 7a and moving lens 2. Consequently, the focal length is adjusted initially with ease.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a zoom lens focus adjustment mechanism for moving a lens in the optical axis direction when initially adjusting the focus of the zoom lens.

[Conventional technology]

2. Description of the Related Art There are zoom lenses that can take photographs by continuously changing the focal length by appropriately moving a lens group. 2. Description of the Related Art In recent years, so-called compact cameras have become popular so that photos can be easily taken, and compact cameras with zoom lenses have been developed, which are equipped with zoom lenses.

The conventional drive mechanism for this type of zoom lens is a double lens barrel in which an outer lens barrel is fitted into an inner lens barrel, with one lens barrel fixed to the camera body and the other freely rotating around the optical axis. year,
By rotating this other lens barrel, the lens group is moved in the optical axis direction.

In other words, a linear groove along the optical axis is formed on either the inner or outer barrel, and a spiral cam groove corresponding to the number of lens groups is formed on the other lens barrel. The pin implanted in the mount is inserted into both the linear groove and each cam groove. When one lens barrel is rotated, the pin is guided by both the linear groove and the cam groove, so the linear groove restricts the direction of movement, and the cam groove restricts the distance of movement, allowing the lens group to move. . The focal length is changed by moving this lens group.

In the manufacturing process of the lens, errors with respect to the design values occur, so when the lens is attached to the camera body, the focus must be adjusted so that it is focused on the film plane, and the adjustment for this purpose is necessary. There must be.

As mentioned above, among conventional zoom lenses, in a two-group zoom consisting of a front group lens and a rear group lens, a spacer of an appropriate thickness is interposed between the rear end of the fixed lens barrel and the camera body to achieve the shortest focus. The focus is adjusted at the distance position, and after this adjustment, the lens group is moved to the longest focal length position, and the front lens group is moved in the optical axis direction to adjust the focus. and,
Repeat this adjustment several times to bring the focus to the film plane.

[Problem that the invention seeks to solve]

By the way, in compact cameras, etc., a movable lens barrel equipped with a front group lens is moved forward and backward with respect to a fixed frame by the rotation of a motor, and a lever linked to this movement is swung to move the rear group lens forward and backward to change the focal length. I have a zoom lens. Compact cameras like this one use a gear train to transmit the rotation of the motor to the zoom mechanism, but in order to make the camera more compact, it is necessary to arrange this transmission element on a fixed frame. is desirable. For this purpose, it is necessary to maintain a predetermined positional relationship between the fixed frame and the camera body, and adjusting the position by interposing a spacer as in the conventional method is not an answer.

Also, because the focus is adjusted, the distance between the fulcrum and the point of action of the lever when the lens group is at the shortest focal length position differs from the designed value.

It is not possible to maintain focus at intermediate focal length positions.

Therefore, the present invention has been developed to enable focal points to be adjusted at the shortest focal length position and the longest focal length position without intervening a spacer or the like between the camera body and the fixed frame, and without changing the length of the lever for moving the lens group. It is an object of the present invention to provide a focusing mechanism for a zoom lens that can be adjusted.

[Means for solving problems]

In order to achieve the above object, in the focus adjustment mechanism according to the present invention, a movable lens barrel provided with a fixed lens moves forward and backward in the optical axis direction, and a movable lens interlocked with the movable lens barrel maintains a predetermined relationship with the fixed lens. A zoom lens that changes the focal length by moving forward and backward with a focus adjustment pin having a driving member that is interlocked with the forward and backward movements for the movement jl, a fulcrum pin, and an eccentric pin whose center is located at a position offset from the center of the fulcrum pin. The fulcrum pin is connected to a driving member, and the eccentric pin is connected to the movable lens, so that the movable lens is interlocked with the movement of the movable lens barrel.

[For production]

When the fulcrum pin connected to the drive member is rotated, the eccentric pin pivots about the center of the fulcrum pin. Since the moving lens is linked to the eccentric pin, the position of the moving lens in the optical axis direction changes depending on the linking position of the eccentric pin and the moving lens.

On the other hand, even if the fulcrum pin is rotated, the linking position between the driving member and the fulcrum pin does not change, so the distance between the centers of the driving member and the fulcrum pin does not change.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS The focus adjustment mechanism of a zoom lens according to the present invention will be specifically described below based on the illustrated embodiments.

First, based on FIG. 3, the structure of a lens drive section of a compact camera equipped with a zoom lens equipped with this focus adjustment mechanism will be described.

This zoom lens has a front lens group 1 as a fixed lens.
This is a two-group zoom consisting of the rear lens group 2 and the rear lens group 2 as a moving lens. The front group lens 1 is housed in the shutter unit 3,
This shutter unit 3 is fixed to the front part of the movable mirror fM4 with three setscrews 3a. Incidentally, the inclination of the front group lens 1 in the optical axis direction can be adjusted by interposing spring washers 3b between two of the set screws 3a.

Furthermore, the mechanism for moving the front group lens 1 in the optical axis direction for initial focus adjustment is constructed in the same manner as conventionally known mechanisms. For example, a protrusion protruding in the optical axis direction is provided on the lens mount of the front group lens 1, and a focusing ring with an uneven cam surface formed on a surface perpendicular to the optical axis is arranged such that the cam surface is always in contact with the protrusion. The focus adjustment ring is rotated to move the front group lens 1 in the optical axis direction.

The movable lens barrel 4 has a substantially rectangular parallelepiped frame-like member with a mounting plate 4a for fixing the shutter unit 3 thereon. A guide hole 4b is provided at the rear of the upper surface of the movable lens barrel 4 by forming a substantially rectangular through hole parallel to the optical axis.
b, by inserting the protrusion 5a formed at the upper end of the lens mount 5 of the rear group lens 2 into the rear group lens 2.
is arranged at the rear of the movable lens barrel 4.

A guide portion 5b is provided by forming a through hole in a direction parallel to the optical axis at the lower side end portion of the lens mount 5, and a bushing 5c is fitted into this guide portion 5b. A rear group guide rod 6a is inserted into this bushing 5c, and the tip of the rear group guide bar 6a on the movable lens barrel 4 side is supported by a support provided within the movable lens barrel 4. A presser plate 6b is brought into contact with the rear end of the rear group guide bar 6a, and the presser plate 6b is fixed to the movable lens barrel 4 with a set screw 6c. A push spring 6d is wound between the lens mount 5 of the rear group guide shaft 6a and the support part in the movable lens barrel 4, and the lens mount 5 transfers the restoring force between the guide hole 4b and the rear group. It is biased so that it is guided by the guide bar 6a and moves rearward.

A suitable recess is formed in the lower surface of the lens mount 5, and the eccentric pin 7a and the flange 7b of the focusing pin 7 are fitted into this recess, and the holding plate 7C is fixed to the lens mount 5 with a set screw 7d. By attaching the focus adjustment pin 7 to the lens mount 5. A circular fulcrum pin 7e is formed on the focus adjustment pin 7 fixed to the lens mount 5, and the fulcrum pin 7e is passed through the through hole 7f of the holding plate 7C to connect the interlocking lever 8 as a driving member.
Loosely insert it into the interlocking hole 8a. Note that the relationship between the lens mount 5, focus adjustment pin 7, and interlocking lever 8 will be described in detail later.

The interlocking lever 8 is approximately L-shaped, and the interlocking hole 8a is formed at the tip of one arm thereof. A through hole 8b is formed in the bent portion of the L-shape, and a support screw 8c passing through the through hole 8b is tightened to the lower surface of the movable lens barrel 4, and the interlocking lever 8
is provided to the movable lens barrel 4 so as to be rotatable around this support screw 8c. Further, at the tip of the other arm of the interlocking lever 8, there is provided an interlocking pin 8d that projects in a direction opposite to the movable lens barrel 4.

A cam portion 9 is provided at the rear side of the movable lens barrel 4 by forming a through hole.

Further, a main guide portion 4C having a through hole formed in the optical axis direction is provided at the side end portion of the upper surface of the movable lens barrel 4, and a bushing 4d is fitted into this main guide portion 4c. A cam plate 10 having a cam surface 10a is fixed to the side of the main guide portion 4c. Note that this cam plate 10 may be made in common with the main guide portion 4c, and the cam surface 10a may be formed on the side surface of the main guide portion 4C. At the lower part of the side surface of the movable lens barrel 4 opposite to the side surface on which the cam portion 9 is provided, there is provided a sub-guide portion 4e whose tip portion is cut out into a substantially U-shape, as shown by a broken line.

As described above, the movable lens barrel 4 with the front group lens 1, the rear group lens 2, the interlocking lever 8, etc. attached is attached to the camera body A (the fourth
(Illustrated) is housed in a fixed frame II fixed to the frame II. At this time,
The main guide bar 4f is inserted into the main guide part 4c, and the support part Lla located above the rear end of the fixed frame 11 supports the rear end of the main guide bar 4f.・Also, insert the sub-guide bar 4g into the notch at the tip of the sub-guide part 4e,
Support part 1 whose rear end is provided on the inner side surface of fixed frame 11
1b to support it. Then, on the front peripheral edge of the fixed frame 11,
The frame-shaped lid 12 is fixed by tightening with a set screw 12a.

As shown in FIGS. 3 and 4, the lower surface of the fixed frame 11 is provided with a cam hole 13 in which a cam surface 13a is formed, with which the side surface of the interlocking pin 8d of the interlocking lever 8 comes into contact.

Further, a worm 14 having a rotation axis in the vertical direction is disposed on the side surface of the fixed frame 11. The rotation axis of this worm 14 is made to protrude above the upper surface of the fixed frame 11, and a drive gear is attached to this protrusion. 15 is fitted. On the upper surface of the fixed frame 11, a gear train 16 including an appropriate number of gears such as a gear 16a and an appropriate reduction ratio is arranged, and the rotation of a motor (not shown) is transmitted to the driving gear 15 via the gear train 16. . A worm wheel 17 pivotally supported on the side surface of the fixed frame 11 meshes with the worm 14, and a transmission gear 18 is provided coaxially with the worm wheel 17. These worm wheels 1
7 and the transmission gear 18 are mutually rotatable, and by applying an appropriate frictional force between their sides, when the load applied to these gears exceeds a predetermined value, one of the gears stops. However, the other gear is set to idle.

The transmission gear 18 includes an intermediate gear 1 pivotally supported on the fixed frame 11.
9 are in mesh with each other, and a gear for driving the encoder 2o and a fan-shaped gear 21 are in mesh with this intermediate gear 19.

The rotating shaft 21a of the sector-shaped gear 21 passes through a through hole 11c formed on the side surface of the fixed frame 11, and the tip of the rotating shaft 21a is connected to a notch 4 formed at the rear lower end of the movable lens barrel 4.
h and is located inside the movable lens barrel 4 housed in the fixed frame 11. The base end of the input lever 22 is fixed to the tip of the rotation shaft 21a by a set screw 22a, so that the input lever 22 and the sector gear 21 do not rotate in synchronization. A drive pin 22b is provided at the free end of the input lever 22 and extends toward the sector gear 21, and the drive pin 22b is loosely inserted into the cam portion 9 formed on the side surface of the movable lens barrel 4. It is.

The upper surface of the fixed frame 11, and the movable lens barrel 4 accommodated therein.
A through hole lid having a shape corresponding to the cam surface 10a is formed in a portion located substantially above the cam plate 10.

Further, on the upper surface of the fixed frame 11, an interlocking plate 23 is rotatably supported approximately at the center thereof by a set screw 23a. A downwardly directed engagement pin 23b is protruded from one end of the interlocking plate 23, and this engagement pin 23b passes through the through hole lid and comes into contact with the cam surface 10a of the cam plate 10. . An upwardly directed input pin 23c is protruded from the other end of the interlocking plate 23, and this input pin 23c is interlocked with a magnification change mechanism (not shown) of the finder. In addition, the interlocking plate 23 is.

It may be supported pivotably on the camera body A or the finder case.

Next, the details of the relationship between the lens mount 5, focus adjustment pin 7, and interlocking lever 8 will be explained based on FIGS. 1 and 2.

The focus adjustment pin 7 is, as shown in FIGS. 1 and 2,
An eccentric pin 7a and a fulcrum pin 7e are formed by protruding from each surface of the flange portion 7b, and the fulcrum pin 7e and the flange portion 7b are concentric, and the center of the eccentric pin 7a is centered on the fulcrum pin 7.
It is offset by an appropriate distance from the center of e.

In the recess 30 formed on the lower surface of the lens mount 5, the flange 7b of the focusing pin 7 can be loosely inserted, and an oval first recess 31 whose longitudinal direction is parallel to the optical axis is formed. However, the eccentric pin 7a can be inserted loosely into the substantially central part of the first recess 31, and the first recess 31
An oval second recess 32 whose longitudinal direction is a direction intersecting the longitudinal direction of the recess 32 is formed. And focus adjustment pin 7
The eccentric pin 7a is placed in the second recessed portion 32, and the eccentric pin 7a is placed in the first recessed portion 31.
The flange portion 7b is positioned at and fitted into the recessed portion 30.

Further, as shown by the dotted chain line at the top of FIG. 2, the interlocking hole 8a formed in the interlocking lever 8 is a long hole, and the fulcrum pin 7e is loosely inserted into the interlocking hole 8a.

The operation of the focus adjustment mechanism according to the present invention constructed as described above will be explained together with the movement operations of the front group lens 1 and the rear group lens 2.

When the motor (not shown) rotates, the drive gear 15 rotates via the gear train 16, and the worm 14 rotates.

When the worm 14 rotates, the worm wheel 17 meshed with the worm 14 rotates, and the frictional force between the worm wheel 17 and the worm wheel 17 causes the transmission gear 18 to rotate. This transmission gear 1
8 is transmitted to the fan-shaped gear 21 via the intermediate gear 19, and the fan-shaped gear 21 rotates in the direction of arrow P in FIG. 3 about the rotation shaft 21a. Note that the rotation of the motor when rotating the fan-shaped gear 21 in this direction is assumed to be forward rotation.

When the sector gear 21 rotates, the input lever 22 coaxially with the sector gear 21 swings in the same direction in synchronization. Therefore, the drive pin 22b of the input lever 22 rotates in the same direction as the sector gear 21 around the rotation shaft 21a. This rotation of the drive pin 22b pushes the cam portion 9, and the drive pin 22b moves from the upper end of the cam portion 9 to the lower end. Therefore, the movable lens barrel 4 forming the cam part 9 is guided by the main guide part 4c and the sub-guide bar 4g, and moves forward with respect to the fixed frame 11.
That is, it moves toward the subject. A shutter unit 3 including a front lens group 1 is fixed to the front part of the movable lens barrel 4, and the front lens group 1 also moves forward.

When the movable lens barrel 4 moves forward, the interlocking lever 8 that is pivotally supported by the movable lens barrel 4 also moves in the same way. The interlocking pin 8d of the interlocking lever 8 is connected to the cam surface 1 of the cam hole 13 formed in the fixed frame 11.
3a, when the interlocking lever 8 moves forward with respect to the fixed frame 11, the interlocking lever 8 is guided by the cam surface 13a and rotates counterclockwise in FIG. 4 about the support screw 8c. do. On the other hand, since the lens mount 5 of the rear group lens 2 is connected to the interlocking lever 8 via the focus adjustment pin 7, the rotation of the interlocking lever 8 causes the push spring 6d to
The lens mount 5 moves forward with respect to the movable lens barrel 4 against the restoring force. Therefore, the rear group lens 2 moves forward with respect to the movable lens barrel 4, narrowing the distance from the front group lens 1, and changing the focal length continuously. When the movable mirror J14 moves to the frontmost position, the front group lens 1 and the rear group lens 2 are located at the most forward position, the rear group lens 2 is closest to the front group lens 1, and the focal length is the longest. Become. Further, the drive pin 22b is located at the lower end of the cam portion 9, and the tip of the movable lens barrel 4 is in a position protruding from the fixed frame 11.

Note that in order to ensure the optical positional relationship between the front group lens 1 and the rear group lens 2 when zooming, the cam surface 13
What is necessary is to design the cam curve of a to be a predetermined one.

In order to move the movable lens barrel 4 backward from the state where the drive pin 22b is located at the lower end of the cam portion 9 and the movable lens barrel 4 is located at the forefront, a motor (not shown) may be rotated in the reverse direction.

Due to the reverse rotation of the motor, the fan-shaped gear 21 moves to the opposite arrow mark P in Fig. 3.
Since the drive pin 22b rotates in the same direction, the drive pin 22b also rotates in the same direction. Therefore, contrary to the above, the movable lens barrel 4 retreats while being accommodated in the fixed frame 11.

A push spring 6 is used to keep the lens mount 5 always moving backwards.
d, and the interlocking lever 8 receives a force to rotate clockwise in FIG.
It is in contact with 3a. Therefore, the interlocking pin 8d is guided by the cam surface 13a and rotates clockwise in FIG. 4 about the support screw 8c. Therefore, the fulcrum pin 7e also rotates in the same direction, and the lens mount 5 retreats with respect to the movable lens barrel 4.

As a result, the rear group lens 2 moves backward, and in cooperation with the retreat of the front group lens 1 accompanied by the movable lens barrel 4, the focal length is continuously changed to the shortest distance.

When initially adjusting the focal length, the fulcrum pin 7e of the focus adjustment pin 7 is rotated with the rear group lens 2 at a temporarily determined position relative to the interlocking lever 8.

As a result, the eccentric pin 7a presses the side surface of the second oval recess 32 while moving in the longitudinal direction.

In response to this pressing force, the focus adjustment pin 7 moves to the flange portion 7b.
Since the first recess 31 is engaged with the oval first recess 31, the first recess 31 moves relative to the flange 7b. The lens mount 5 in which the recessed portion 30 is formed is connected to the guide hole 4b.
Since the first recessed portion 31 moves relative to the flange portion 7b, the lens mount 5 moves relative to the focusing pin 7 in the optical axis direction. means. Moreover, focus adjustment pin 7
Since only the fulcrum pin 7e is rotated within the interlocking hole 8a of the interlocking lever 8, the distance between the pivoting center of the interlocking lever 8 and the fulcrum pin 7e is not changed. That is, the focus can be adjusted by moving the rear group lens 2 in the optical axis direction without changing the distance between the centers of the interlocking lever 8 and the fulcrum pin 7e. After adjusting the focus appropriately in this way,
Tighten the set screw 7d to press the holding plate 7c against the focus adjustment pin 7 and fix it.

In this embodiment, a telephoto type zoom lens in which the front group lens 1 and rear group lens 2 move forward to create a long focal point has been described, but this is also a retrofocus type zoom lens in which each lens group moves backward to create a long focal point. I don't mind.

In addition, the structure in which the front group lens 1 is fixed to the movable lens barrel 4 and the rear group lens 2 is advanced or retracted by moving the movable lens barrel 4 forward or backward has been explained. has a structure in which it moves forward and backward in conjunction with the movement of the moving lens barrel.
This front lens group and an interlocking lever, which is a driving member, may be linked by a focus adjustment pin. Alternatively, all the lens groups may be linked with the movement of the movable lens barrel using linkage levers, and each may be linked with a focus adjustment pin.

〔Effect of the invention〕

As explained above, according to the zoom lens focus adjustment mechanism according to the present invention, the lens group can be moved in the optical axis direction simply by rotating the focus adjustment pin, so initial adjustment of the focal length can be easily performed. . Moreover, since initial adjustments can be made without changing the distance between the drive member and the fulcrum pin of the focus adjustment pin, the lens group can be moved as designed as possible, and the focus during zoom operations can be reliably aligned with the film plane. I can be anxious.

Moreover, since there is no need to insert a spacer or the like between the fixed frame and the camera body to adjust the focus, the motor power transmission element can be easily placed on the fixed frame, giving you greater freedom in designing the arrangement. At the same time, the camera can be made smaller.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view showing the main parts of the focus adjustment mechanism according to the present invention from the bottom. FIG. 2 is also a bottom view. FIG. 3 is an exploded perspective view showing an embodiment of a zoom lens equipped with a focus adjustment mechanism according to the present invention. FIG. 4 is a partial cross-sectional view taken along a horizontal line in which the movable lens barrel is housed in the fixed frame. 1... Front group lens (fixed lens) 2... Rear group lens (movable lens) 4... Movable lens barrel 5... Lens mount 7
... Focus adjustment pin 7a... Eccentric pin 7b...
・Flange part 7c... Holding plate 7d... Set screw 7e... Fulcrum pin 8... Interlocking lever (driving member) 8a... Interlocking hole 8c... Support screw 8d
...Interlocking pin 11...Fixed frame 21...
Fan-shaped gear 21a...Rotation shaft 22...Inlet pin 22a...Set screw 22b...Drive pin A...Camera body Patent applicant Fuji Photo Kohki Co., Ltd. Patent applicant Fuji Photo Film Co., Ltd. Figure 1 Figure IIZ Figure 4

Claims (1)

[Claims] A zoom lens in which a movable lens barrel provided with a fixed lens moves forward and backward in the optical axis direction, and a movable lens linked to the movable lens barrel moves forward and backward in a predetermined relationship with the fixed lens, thereby changing the focal length. It consists of a driving member that moves forward and backward of the lens barrel, and a focusing pin that has a fulcrum pin and an eccentric pin whose center is offset from the center of the fulcrum pin, and the fulcrum pin is used as the driving member and the eccentric pin is moved as described above. A focus adjustment mechanism for a zoom lens, characterized in that the movable lens is linked to each lens so that the movable lens moves in conjunction with the movement of the movable lens barrel.