JP3358032B2 - Zoom lens barrel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zoom lens barrel comprising a plurality of lens groups. More specifically, the present invention relates to a zoom lens in which the same drive source is used to drive different lenses during zooming and during focusing. It relates to the lens barrel.

[0002]

2. Description of the Related Art In a conventional zoom lens barrel, different driving means are provided for zooming and focusing, so that the size of the lens barrel and the camera body are increased, and the number of parts is large. Had caused the high.

To solve this problem, Japanese Patent Application Laid-Open No. 61-259210 discloses a configuration in which zooming and focusing are continuously repeated by the same driving means. In this publication, a cam shape is set so that focusing is performed by moving the lenses of the front and rear groups to zoom to a predetermined focal length, and then moving the front and rear group lenses with a constant lens interval. With this configuration, continuous zooming cannot be performed and intermittent zooming occurs.However, zooming and focusing are performed by driving the same movable body, so that the camera can be reduced in size and cost can be reduced. To contribute.

[0004]

However, in the configuration of the above publication, zooming and focusing are repeated, so that there is a problem that a user can select only a predetermined focal length even with a zoom lens barrel. Up
In addition, since the shape of the cam groove of the movable body is set so as to perform focusing by moving the front and rear group lenses at a constant lens interval, a very high precision cam groove is required.
Therefore , when molding a cylinder having a cam groove with a resin, a very complicated, high-priced, high-performance mold is required. The present invention has been made in view of such a problem, and has a very high efficiency.
When focusing requires precision lens movement
No relatively high-precision lens movement is required without cam drive.
Has cam groove only when cam is driven during zooming
Easier resin molding of cylinder and expensive for machining cam groove
And eye <br/> manner to propose a zoom lens barrel which eliminates the need for a mold.

[0005]

The above object is achieved by any of the following means. A first moving frame that carries a predetermined group of zoom lenses including a plurality of lens groups, a second moving frame that carries another group of zoom lenses ,
A helicoid screw-engaged with the first moving frame and the second moving frame and the cam
In a zoom lens barrel having a combined drive cylinder ,
A cam pin is provided on one of the drive cylinder and the second moving frame.
And a wide cam groove is provided on one of the other, and
One, with a lockable locking means said second moving frame, when zooming, before without locking operation of the locking means
The driving cylinder moves the first moving frame and the second moving frame in an optical axis direction.
Direction, and at the time of focusing, the second moving frame is locked by the locking means, and the driving cylinder is
A zoom lens barrel, wherein only the first moving frame is moved in an optical axis direction while moving a pin away from a side wall of the cam groove . A first moving frame carrying a predetermined group of zoom lenses including a plurality of lens groups, a second moving frame carrying another group of the zoom lenses, and the first moving frame
Drive that is helicoidally screwed with the second moving frame and cam-engaged with the second moving frame
A driving cylinder in the zoom lens barrel comprising:
And providing a cam pin on one of the second moving frames.
In both cases, a wide cam groove is provided in one of the other, and a locking means capable of integrally locking the first moving frame and the second moving frame is provided. In zooming, the locking means is provided. wherein the drive cylinder without a locking operation between the first moving frame of the second
The moving frame is moved in the optical axis direction, and at the time of focusing, the first moving frame and the second moving frame are integrally locked by the locking means, and the driving pin moves the cam pin forward.
The first moving frame while being separated from the side wall of the cam groove;
A zoom lens barrel, wherein the second moving frame is moved in an optical axis direction .

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail with reference to FIGS.

FIGS. 1 and 2 are basic structural views of a zoom lens barrel according to the present invention. FIG. 1 is a view when the lens barrel is collapsed when the camera is carried, and the upper part of FIG. The figure is a telephoto view at the bottom.

Fc is a front lens group, and Rc is a rear lens group. The present embodiment is a zoom lens that performs zooming by moving these front and rear group lenses, but a fixed lens may be appropriately provided separately from the moving lens, and the front and rear group lenses may be a single lens or a plurality of lenses. It may be configured.
The front group lens Fc is held by the front frame 1, the front frame 1 is screwed to the front group moving frame 2, and the rear group lens Rc is held by the rear group moving frame 3. Reference numeral 4 denotes a movable body rotatably attached to a camera body (not shown) or a fixed member connected to the camera body, and a gear 4a for rotating the movable body 4 is provided at the rear end of the outer diameter. And
The inner diameter is provided with a female helicoid 4b and a cam groove 4c. The front group moving frame 2 is provided with a male helicoid 2a, which is screwed with the female helicoid 4b of the movable body 4, and the rear group moving frame 3 is provided with a cam pin 5 erected to form a cam surface 4 of a cam groove 4c.
d. Reference numeral 11 denotes a straight guide plate, which is attached to a camera body (not shown) or a fixing member connected to the camera body, and an arm 11a bent parallel to the optical axis.
, The front group moving frame 2 is inserted into a hole 2b formed in the front group moving frame 2 to prevent the front group moving frame 2 from rotating. Therefore, the arm 11a may be provided on a part of the circumference around the optical axis, but it is usually preferable to provide two or more arms 11a in order to guarantee the accuracy of the lens optical axis. Reference numeral 13 denotes a guide sleeve erected on the front group moving frame 2, which is provided at a position circumferentially different from the hole 2b,
It is fitted with a guide shaft 14 erected from the rear group moving frame 3. Reference numeral 15 denotes a washer attached to the tip of the guide shaft 14, which holds a compression spring 16 wound around the guide shaft 14 in a compressed state. With this guide shaft 14, the rear group moving frame 3 moves straight along with the front group moving frame 2 in the optical axis direction. Further, the rear group moving frame 3 is constantly drawn in the direction of the front group moving frame 2 by the compression spring 16, and the cam pin 5
Contacts the cam surface 4d of the cam groove 4c on the front group moving frame 2 side,
The other cam groove side has a sufficient margin.

In the zoom lens barrel having the above-described structure, zooming is performed as follows. That is, the gear 4a is driven by a driving source (not shown) from the retracted position in FIG.
When the movable body 4 is rotated, the front group moving frame 2 which is helicoidally screwed with the movable body 4 but is prevented from rotating by the arm portion 11a, as shown in the upper part of FIG. It is paid out. On the other hand, the rear group moving frame 3 cam-coupled to the movable body 4
Also, since the rotation is prevented by the front group moving frame 2 and the guide shaft 14, even if the movable barrel 4 rotates, it does not rotate, and since the cam surface 4d is horizontal with respect to the retracted state, the rear group moving frame 3 Does not move. Thus, a wide-angle focal length is set. Next, when the movable body 4 is further rotated, the front group moving frame 2 and the rear group moving frame 3 are extended by a helicoid and a cam as shown in the lower part of FIG. 2 to perform zooming, and the telephoto focal length is reduced. Is set.

In the zoom lens barrel having the above structure,
A first embodiment relating to focusing will be described with reference to FIGS. The same components as those in FIG. 1 are denoted by the same reference numerals.
The upper part of FIG. 3 is a diagram in which zooming is performed from the retracted position as described above and the focal length is set to a wide angle. This embodiment can be applied to a zoom lens in which the front group lens Fc and the rear group lens Rc move in the same direction during zooming, and one of the groups moves during focusing and the other group does not move.
After setting an arbitrary focal length by zooming, by pressing a release button of a camera (not shown), an electric current flows through an electromagnetic coil 27 provided on the rectilinear guide plate 21, a magnetic field is generated, and the rectilinear The guide plate 21 is excited. A part of the rear group moving frame 3 is always in contact with the straight guide plate 21,
A rear group fixing plate 28 made of a magnetic metal material is fixed. Therefore, the rear group fixing plate 28 is
Is adsorbed. Subsequently, when the movable body 4 is rotated, the rear group moving frame 3 does not move, but only the front group moving frame 2 is extended by a predetermined amount, and focusing is performed. Since the cam groove 4c has a sufficiently wide width, even when the cam groove 4c is rotated only, the cam pin 5 must come into contact with the surface opposite to the cam surface 4d which is always in contact during zooming. There is no. FIG. 4 is a schematic diagram of this, and FIG.
It is a figure which focuses on m. The front lens group Fc moves by a helicoid during zooming and focusing, but the rear lens group Rc moves as indicated by a broken line by a cam during zooming, and does not move in the optical axis direction as indicated by a solid line during focusing. FIG. 4B shows the cam 4
The relationship between d and the cam pin 5 is enlarged, and the cam 4
When d is rotated in the direction of arrow A, the result is the same as the movement of the cam pin 5 in the direction of B, and a gap is created between the cam pin 5 and the cam 4d. Therefore, the cam pin 5 is
16 (similarly to the compression spring 16 in FIG. 1), but does not move against the spring pressure of the cam pin 5; The suction force of 21 needs to be stronger than the spring pressure of the compression spring 16.

FIG. 5 shows a modified example in which the structure shown in FIGS. 3 and 4 is reversed. The movable body 4 and the front group moving frame 2 are connected to each other by a cam. Helicoid coupling,
By exciting the rectilinear guide plate 21, the front group moving frame 2 is attracted and fixed, and focusing is performed by moving the rear group moving frame 3. In FIG. 5A, the zooming direction is the same as that of FIG. 4, but during focusing, the movable body 4 is rotated in the opposite direction, and the rear lens group Rc moves by helicoid both during zooming and during focusing. However, the front group lens Fc moves as indicated by the broken line by the cam during zooming, and does not move in the optical axis direction as indicated by the solid line during focusing. In FIG. 5B, an arrow A indicates a zooming direction, an arrow B indicates a focusing direction, and an arrow C indicates a direction in which the cam pin 5 relatively moves. In addition,
A cam 4d is provided on the right side of the cam groove shown in FIG.
Is biased to the right.

Next, a second embodiment relating to focusing will be described with reference to FIGS. The same components as in FIG. 1 are denoted by the same reference numerals. In the present embodiment, as shown in FIG. 6, when zooming from wide angle to telephoto, the front lens group Fc and the rear lens group Rc are moved out while moving close to each other, and the front lens group Fc and the rear lens group are moved together during focusing. The present invention can be applied to a zoom lens that moves together with a constant lens distance from the lens Rc. The upper part of FIG. 7 is a diagram in which zooming is performed from the retracted position as described above and the focal length is set to a wide angle. The guide sleeve 33 and the guide shaft 34 are formed of a magnetic material, and the outer periphery of the guide sleeve 33 is an electromagnet.
36 are located. When the electromagnetic coil 37 in FIG. 8 is energized, the guide sleeve 33 is excited, and the guide sleeve 33 attracts the guide shaft 34. Therefore, when a desired focal length is set by performing zooming, when the shutter is released, the electromagnetic coil 37 is energized, and the front group moving frame 2 and the rear group moving frame 3 are integrated in the optical axis direction. Front group lens F
c and the rear lens group Rc move in the optical axis direction while maintaining a constant lens distance, and focusing is performed as shown in the lower part of FIG. As shown in FIG. 9, which is a schematic diagram, the moving speed of the rear group lens Rc is slower during focusing than during zooming. Therefore, during focusing, the cam pin 5 resists the spring 38 from the cam surface 4d. And move away. Although the spring 38 is not shown in FIG. 7, like the compression spring 16 in FIG. 1, the front group moving frame 2 and the rear group moving frame 3 are pulled to bring the cam pin 5 into contact with the cam surface 4d. is there.

FIG. 10 shows a modification in which the structure is reversed from those of FIGS. 7 to 9, wherein the movable body 4 and the front group moving frame 2 are connected by a cam.
The movable body 4 and the rear group moving frame 3 are helicoid-coupled, and focusing is performed by integrally moving the front group moving frame 2 and the rear group moving frame 3 as described above. Therefore,
The cam for moving the front group moving frame 2 is different from the previous embodiment only in that the right side of the cam groove in FIG. 10 is used.

FIG. 11 shows an example in which a shape memory alloy is used in place of the electromagnetic coil of FIG. 8, and a thin wire 47 made of a shape memory alloy is wound around the outer periphery of a guide sleeve 43 provided with a cutout 43a in a part. Has been. After zooming, wire 47
When power is supplied to the
The guide shaft 44 is fixed by the guide sleeve 43 because the inner diameter of the lens unit becomes smaller, and the front group moving frame 2 and the rear group moving frame 3 move integrally in the optical axis direction during focusing. Lastly, the correspondence between the terms described in “claims” and the terms described in “embodiments of the invention” will be described. The first moving frame described in claims 1 and 3 corresponds to the front group moving frame 2, and the second moving frame corresponds to the rear group moving frame 3. However, the first moving frame may correspond to the rear group moving frame 3 and the second moving frame may correspond to the front group moving frame 2. Claim 1,
3 corresponds to the movable barrel 4,
Is provided on the movable body 4 and the cam groove 4c is provided on the rear group moving frame 3.
Is also good. The exciting member according to claim 2 corresponds to the electromagnetic coil 27, and the magnetic member corresponds to the rear group fixing plate 28. The exciting member according to claim 4 corresponds to the electromagnet 36. Claim 5
Corresponds to the wire 47. Claim 6
Are equivalent to the compression spring 16 and the spring 38.
You.

[0015]

Effects of the Invention] According to the zoom lens barrel according to claims 1 to 6, when the very focusing a high precision of the lens movement is required cam driven by engagement operation of the locking means
Without, relatively high accuracy to Runode cam driven only when the lens movement is not required for zooming and has a cam groove
Resin molding of the tube is Ri easily name, an effect that expensive molds for the processing of the cam grooves becomes unnecessary. Also, Zumi
And focusing are performed by the same drive cylinder.
In addition to realizing miniaturization and low cost,
User can select any focal length unlike
Also has the effect.

[Brief description of the drawings]

FIG. 1 is a basic view of the present invention, showing a lens barrel retracted.

FIG. 2 is a diagram when zooming is performed in FIG. 1;

FIG. 3 is a diagram of a zoom lens barrel according to the first embodiment.

FIG. 4 is a schematic diagram of the first embodiment.

FIG. 5 is a schematic view of a modification of the first embodiment.

FIG. 6 is a movement diagram of the zoom lens.

FIG. 7 is a diagram of a zoom lens barrel according to a second embodiment.

FIG. 8 is a diagram of an electromagnet according to a second embodiment.

FIG. 9 is a schematic view of a second embodiment.

FIG. 10 is a schematic view of a modification of the second embodiment.

FIG. 11 is an embodiment using a shape memory alloy in the second embodiment.

[Explanation of symbols]

 Fc Front-group lens Rc Rear-group lens 2 Front-group moving frame 3 Rear-group moving frame 4 Movable body 11 Straight-ahead guide plate 13 Guide sleeve 14 Guide shaft 27 Electromagnetic coil 28 Rear group fixing plate 36 Electromagnet 37 Electromagnetic coil

Claims (6)

(57) [Claims] And 1. A first moving frame carrying a predetermined first group of the zoom lens comprising a plurality of lens groups, a second moving frame carrying the other a group of the zoom lens, and the first moving frame Helicoid screwed into the second moving frame
And a driving cylinder engaged with the zoom lens barrel, and a cam pin is provided on one of the driving cylinder and the second moving frame.
The provided with, a wide cam groove provided in the other one, and, the second moving frame equipped with a lockable locking means, when the zooming, without locking operation of the locking means The driving cylinder makes the first moving frame and the second moving frame light.
The lens is moved in the axial direction, and at the time of focusing, the second
The moving frame is locked, and the driving cylinder moves the cam pin to the cam.
Only the first moving frame is separated from the side wall of the groove by the optical axis.
A zoom lens barrel characterized by moving in the direction . 2. A linear guide plate for restricting rotation of the second movable frame, an exciting member for exciting the linear guide plate, and the linear guide plate fixed to the second movable frame. sliding contact consists of a magnetic member, by energizing the linear guide plate by the excitation member, the zoom lens barrel according to claim 1, characterized in Rukoto to adsorb the magnetic member to the rectilinear guide plate. 3. A first moving frame carrying a predetermined first group of the zoom lens comprising a plurality of lens groups, a second moving frame carrying the other a group of the zoom lens, and the first moving frame Helicoid screwed into the second moving frame
And a driving cylinder engaged with the zoom lens barrel, and a cam pin is provided on one of the driving cylinder and the second moving frame.
The provided with, either the wide cam groove provided in the other, and comprises integrally lockable locking means and said first moving frame and the second movable frame, when zooming, the engagement The driving cylinder makes the first moving frame and the second moving frame light without the locking operation of the stopping means.
The lens is moved in the axial direction, and at the time of focusing, the first
The moving frame and the second moving frame are integrally locked , and the driving
While the cylinder separates the cam pin from the side wall of the cam groove,
Wherein the first moving frame and the second moving frame are moved in the optical axis direction . 4. A guide shaft formed of a magnetic material, wherein the locking means is provided on the second moving frame, a guide sleeve provided on the first moving frame and fitted to the guide shaft, and the guide means. It consists of a magnetizing member for magnetizing the sleeve, the zoom lens barrel according to claim 3, characterized in Rukoto adsorb the guide shaft to the guide sleeve by energizing the guide sleeve by the exciting member. 5. A guide sleeve, wherein said locking means has a guide shaft erected on said second moving frame and at least one slot provided on said first moving frame and fitted with said guide shaft. When formed from a shape memory alloy consists of a winding member wound the guide shaft, to grip said guide shaft to said guide sleeve by deforming the winding member by supplying an electric current to the winding member < The zoom lens barrel according to claim 3, wherein: 6. The cam pin is provided on a predetermined side wall of the cam groove.
The zoom lens barrel according to claim 1, further comprising an urging member that urges the zoom lens in a direction in which the zoom lens barrel comes into contact with the zoom lens barrel.