JP2946314B2 - Zoom lens barrel - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zoom lens barrel, and more particularly, to independent operation members for zooming drive and focusing drive, that is, a zooming operation member and focusing. The present invention relates to a zoom lens barrel performed by selectively rotating an operation member. 2. Description of the Related Art In a conventional zoom lens barrel of this kind, a lens group is divided into two for focusing driving, one lens group is used for a cam frame for zooming drive, and the other lens group is used for a zooming drive cam frame. Each was attached to a helicoid, and focusing was performed by rotating the helicoid. By the way, in recent years, the magnification of zoom lenses has been increasing, and the lens configuration has become more complicated. The lens driving method for focusing has been changed from front focus to inner focus or rear focus in consideration of such a complicated lens configuration as well as further downsizing and improvement of operability. For this reason, a driving force transmission system for transmitting a rotational force to a helicoid that supports a moving lens group for focusing supports a cam frame and each lens group that are rotated by zooming drive. However, there is a problem that the mechanism cannot be disposed unless the zoom fixing ring is broken through, resulting in a very complicated mechanism. In addition, since helicoids are used as the lens frame for supporting the focusing lens, the load at the time of focusing driving becomes heavy. Particularly, in the case of AF (autofocus) zoom, the load on the driving motor increases, so that the load becomes large. A drive motor having a large capacity is required, which necessitates an increase in the size and weight of the apparatus and an increase in power consumption. SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and its object is to be able to cope with a complicated lens configuration, to reduce the number of components, and to reduce the cost. An object of the present invention is to provide a zoom lens barrel that can greatly reduce the torque for zooming drive and focusing drive with the configuration. [0005] In order to achieve the above object, the present invention provides
In a zoom lens barrel composed of a plurality of lens groups,
Straight grooves along the optical axis and cam grooves inclined with respect to the optical axis
With a fixing ring, and with respect to the fixing ring in the optical axis direction.
A zooming operation member that is rotated manually or electrically in a state where movement of the
A focusing operation member that is manually or electrically rotated while being prevented from moving in the optical axis direction, and a plurality of focusing operation members.
Each on the lens frame that holds the zooming lens group
A plurality of fixed pins and an optical axis with respect to the fixing ring;
In the state where movement in the direction is prevented, the zooming operation member is driven to rotate , and
Allowed to move in the optical axis direction of the plurality of zooming lens group for cooperation with serial pin, having an inclination with respect to the optical axis
A first cam frame having a cam groove, and a pair of the first cam frame and the first cam frame.
The first cam is allowed to move in the optical axis direction.
The frame is driven to rotate integrally by the frame,
And the cooperative action of the cam groove and the pin
To move the lens group for zooming in the optical axis direction.
The second also has a cam groove and a rectilinear groove along the optical axis.
F and the cam frame, a rotational driving of the focusing operating member
The driving is converted into the optical axis direction driving of the second cam frame only via the focusing cam means without the intermediary of the recoid screw means, and the pipe engaging with the cam groove of the second cam frame is converted.
Only the lens frame with the
A focusing drive regulating member for moving in the optical axis direction together with the lens group which is made comprises a. An embodiment of the present invention will be described below in detail with reference to FIGS. 1 to 3. FIG. 1 is a cross-sectional view showing a cross-sectional configuration of an embodiment of the present invention, FIG. 2 is a developed view showing a zooming drive restricting member and a focusing drive restricting member in the embodiment, and FIG. FIG. 6 is a diagram showing a movement locus of each lens group constituting the lens group. In FIGS. 1 and 2, the base (that is, the rear end, the right end in FIG. 1) of the zoom lens barrel is detachably attached to a lens mount fixed to the front of a camera body (not shown). (In this example, a bayonet mount) 1 is provided. The rear end of the cylindrical index ring 2 is fitted and fixed inside the annular portion at the front of the mount 1. A fixing ring 2a for holding the lens when attaching and detaching the lens is fitted and fixed to the outer peripheral portion of the rear end of the index ring 2. The index ring is provided slightly forward of the portion where the fixing ring 2a is provided. A zoom ring 3 as a zooming operation member is slidably fitted with the zoom ring 2 so as to be rotatable with respect to the zoom ring 2. A fixed frame 4 for holding the fifth lens group 5 as a fixed lens is attached to the rear end of the index ring 2 by a set screw. Further, a zoom fixing ring 6 is fixed to and integrated with the index ring 2, and the index ring 2 and the zoom fixing ring 6 form a double cylinder. A rotatable first cam frame 8 as a zooming drive restricting member is slidably fitted between the double cylinders, and a zoom pin 8a is implanted in the cam frame 8 by screw means. A lens frame 9 provided with an aperture 10 and a third lens group 11 is slidably fitted inside the intermediate portion of the zoom fixing ring 6. Roller pins 9a are implanted (screwed) into the lens frame 9. Further, a lens frame 12 on which the fourth group lens 13 is fixed is located at a position further rearward on the inner periphery of the zoom fixing ring 6.
Are inserted so as not to hinder the sliding operation of the lens frame 9 and to be slidable. Roller pins 12a are implanted in the lens frame 12. A flange-shaped protrusion 6e is formed on the outer periphery of the central portion of the zoom fixing ring 6, and the front end of the first cam frame 8 abuts on the protrusion 6e. The rear end of the frame 8 is pressed by a cam pressing ring 7 screwed from behind, so that the first cam frame 8 is prevented from moving in the optical axis direction, and is allowed to rotate only. Become. At the front of the first cam frame 8, a straight key 14 extending in the optical axis direction (forward) is mounted with a mounting screw 14a, and the tip of the straight key 14 is zoomed. It engages with a straight groove (key groove) 15d formed along the optical axis in a second cam frame 15 which is slidably fitted on the front half of the fixed ring 6 so as to be rotatable and slidable.
As a result, the second cam frame 15 as another zooming drive restricting member rotates around the zoom fixing ring 6 integrally with the first cam frame 8 in the rotation direction, but in the optical axis direction. Can be moved independently.
The zoom pin 8 implanted in the first cam frame 8
“a” penetrates a groove formed in the rotation direction perpendicular to the optical axis of the index ring 2 and fits with the groove 3 a of the zoom ring 3. A roller pin 9a implanted in the lens frame 9 passes through a rectilinear groove 6a formed in the zoom fixing ring 6 along the optical axis and intersects the first cam frame 8 with the optical axis. It is fitted (engaged) with the cam groove 8c formed as described above. Further, the roller pin 12a implanted in the lens frame 12 penetrates a rectilinear groove 6b along the optical axis formed on the zoom fixing ring 6, and is fitted into a cam groove 8b formed on the first cam frame 8. doing. The lens frame 17 to which the first group lens 18 is fixed is slidably fitted on the inner periphery of the zoom fixing ring 6.
In the vicinity of the rear end of the roller 7, a roller pin 17a is implanted in a screwed state. The roller pin 17a penetrates a cam groove 6c formed in the zoom fixing ring 6, and is formed in the second cam frame 15 along a straight groove 1 formed along the optical axis direction.
5a. Further, the second group lens 20 fitted and held in the lens frame 19 is fixed in a state where the rear end portion is pressed by the ring nut 21. The lens frame 19 and the lens frame 17 are fitted into the zoom fixing ring 6 so as not to hinder each other of the rotation and the axial movement. A roller pin 19a is implanted in the lens frame 19 in a screwed state.
The roller pin 19a fits into a cam groove 15b formed in the second cam frame 15 through a straight groove 6d formed in the zoom fixing ring 6 along the optical axis direction. A distance fixing ring 16 is provided on a flange-shaped protrusion 6e formed on the outer periphery of the center of the zoom fixing ring 6.
Is fixed to the outer periphery of the distance fixing ring 16 so as to be rotatable, and a distance ring 22 as a focusing operation member is formed between the distance ring 22 and the distance fixing ring 16. An intermediate ring 23 is inserted in the gap thus set. This intermediate ring 23
Since the guide pin 16a implanted in the distance fixing ring 16 is fitted in the long groove 23a formed in the optical axis direction,
It can move in the axial direction, but cannot rotate. Further, the intermediate ring 23 has a distance transmitting pin 2
3b is implanted, and the distance transmission pin 23b is provided on the inner periphery of the distance ring 22 so as to correspond to the amount of extension of the second lens unit 20 and the rotation angle of the distance ring 22 for focusing. It is fitted into a cam groove 22a formed on the surface. A cam frame restricting pin 23c is further fixed to the intermediate ring 23.
3c is a relief hole 16b formed in the distance fixing ring 16.
And fitted in a long groove 15c formed in the second cam frame 15 in a direction orthogonal to the optical axis. Therefore, this second
The cam frame 15 has a cam frame regulating pin 23c fitted into its long groove 15c, an intermediate ring 23 and a distance transmitting pin 2c.
3b and the cam groove 22a restrict the movement in the optical axis direction. Reference numeral 22 b denotes a subject distance display engraved on the outer peripheral surface of the distance ring 22, and a focal length display (not shown) is also engraved on the outer peripheral surface of the zoom ring 3. Here, the rotating operation of the focusing operation member (the distance ring 22 in this example) is performed by focusing cam means (in this example, the pin 23b and the cam groove 22a, the guide pin 16a and the long groove 23a, and the cam frame regulating pin 23c). And a long groove 15c, a roller pin 19a and a cam groove 15b) to convert the driving into the optical axis direction and to move a part of the zooming lens group (the second group lens 20 in this example) in the optical axis direction. Focusing is referred to as a drive restricting member. Next, the operation of the zoom lens barrel according to the present embodiment having such a configuration will be described. First,
When performing a zooming operation, the zoom ring 3 is driven to rotate by an electric motor manually or via a rotational force transmission system (not shown). Then, the groove 3a of the zoom ring 3
The first cam frame 8 rotates with respect to the outer periphery of the zoom fixing ring 6. Since the position of the first cam frame 8 is regulated while being sandwiched between the protruding portion 6c and the cam pressing ring 7, it does not move in the optical axis direction. The rotation of the first cam frame 8 pushes the rectilinear groove 15d of the second cam frame 15 in the circumferential direction via the rectilinear key 14, and the second cam frame 15 is integrated with the first cam frame 8. And rotate. When the second cam frame 15 rotates, a cam groove 6c formed in the zoom fixing ring 6, a straight groove 15a formed in the second cam frame 15, and these grooves 6c, 1
The roller pin 17a moves in the optical axis direction while rotating about the optical axis by the cooperative action with the roller pin 17a engaged with 5a. The roller groove 19b formed in the second cam frame 15 and the roller pin 19a engaged with the rectilinear groove 6d and the cam groove 15b cooperate to move the roller pin 19a in the optical axis direction. Therefore, the lens frame 17 on which the roller pins 17a are planted and the lens frame 19 on which the roller pins 19a are planted
The group lens 18 and the second group lens 20 are respectively moved in the optical axis direction. That is, when the zoom ring 3 is driven from the wide side to the tele side, the first group lens 18 is extended in the direction in which the first group lens 18 is extended, and the second group lens 20 It moves in the direction in which it is rolled in like a trajectory indicated by reference sign B. Conversely, when the zoom ring 3 is driven from the telephoto side to the wide side, the first group lens 18 moves in the retracting direction and the second group lens 20 moves in the extending direction. On the other hand, by the rotation of the first cam frame 8, the cam grooves 8 b formed in the first cam frame 8 and the rectilinear grooves 6 formed in the zoom fixing ring 6 along the optical axis direction.
b, and a cam groove 8c formed in the first cam frame 8 and a linear groove 6a formed in the zoom fixing ring 6 along the optical axis direction. The roller pins 9a move in the optical axis direction without rotating together. Therefore, the third lens group 11 supported by the lens frame 9 on which the roller pins 9a are mounted and the fourth lens group 13 supported by the lens frame 12 on which the roller pins 12a are mounted are both optical axes. The direction, that is, the corresponding position as indicated by reference numeral C and reference numeral D in FIG. The fifth group lens 5 is fixedly provided at a position indicated by reference numeral E in FIG. 3 by the fixed frame 4, and is not moved by the driving operation of the zoom ring 3. Next, the focusing driving operation will be described. When the distance ring 22 is manually or rotationally driven by an electric motor via a rotational force transmission system (not shown),
A distance transmitting pin 23 engaged with the cam groove 22a by a cam groove 22a formed on the inner periphery of the distance ring 22.
b receives the force in the rotational direction,
The intermediate ring 23 in which b is implanted has its long groove 23a formed along the optical axis direction prevented from rotating by the guide pin 16a implanted in the distance fixing ring 16, so that the intermediate ring 23 has Can only be pushed. Then, the intermediate ring 23 on which the distance transmitting pin 23b is implanted also moves in the optical axis direction as a unit, and along with this movement, the cam frame regulating pin 23c fixed on the intermediate ring 23 and the second ring 23c
Slot 1 formed in a direction perpendicular to the optical axis of the cam frame 15 of FIG.
5c, the second cam frame 15 is moved in the optical axis direction. As described above, when the second cam frame 15 moves in the optical axis direction, of the two roller pins 17a and 19a, the roller pin 17a is the straight groove extending along the optical axis direction of the second cam frame 15. 15a does not move at all, but the roller pin 19a has a spiral cam groove 1
5b, it moves in the optical axis direction. Therefore, only the lens frame 19 on which the roller pin 19a is implanted is maximum along the optical axis direction,
Will be moved by the amount indicated by. Incidentally, such a movement (displacement amount) of the second cam frame 15 in the optical axis direction is absorbed between the rectilinear groove 15d and the rectilinear key 14, so that the first cam frame 8 No driving force is applied in either the optical axis direction or the rotation direction. Therefore, during such a focusing operation, neither the lens frame 9 holding the third group lens 11 nor the lens frame 12 holding the fourth group lens 13 moves (rotates). Of course, the first group lens 1 described above
The lens frame 17 holding the lens 8 does not move (rotate). still,
In FIG. 3, a curve indicated by a symbol B is a zooming movement locus when the second group lens 20 that performs the focusing function is set at a position where the subject is focused on ∞, and a curve indicated by a symbol B ′ is It is a locus of zooming movement when the second group lens 20 is set at a position where an object at a close distance is focused. Accordingly, the distance Δx between the two curves B and B ′ in the optical axis direction corresponds to the amount of extension of the second lens unit 20 from the position ∞ to the closest distance. According to the present embodiment constructed and operated as described above, the zoom drive is restricted in spite of a complicated lens configuration in which five groups of lenses are zoomed out of four groups. The member and the focusing drive regulating member have a relatively simple configuration, and the predetermined moving means of each lens frame is constituted by a cam means comprising a cam groove (or a straight groove) and a roller pin (or a pin). The driving force (torque) required for the driving is small. In particular, in focusing driving, only a part of the cam frame (the second cam frame 15 in this embodiment) needs to be moved by the cam means in the optical axis direction. Therefore, no special members are required as compared with the conventional one, and the rotational torque required for moving the lens is significantly reduced. If you, be small load of focusing driving motor, thus, it is possible to achieve savings of size and weight and power consumption. The present invention is not limited to the above-described embodiment, but can be variously modified without departing from the scope of the invention. For example, in the optical design of the zoom lens, the first lens group 18 described above is used alone or in the first lens group.
In order for focusing to be performed separately from zooming by driving the group lens 18 and the second group lens 20 together, a roller pin 17a implanted in the lens frame 17 holding the first group lens 18 is required. As the shapes of the cams to be engaged, a straight groove along the optical axis direction may be provided on the zoom fixing ring 6, and a cam groove may be provided on the second cam frame 15. In order to transform the embodiment shown in FIGS. 1 to 3 into a rear focus system, a focusing drive including the third group lens 11 and the fourth group lens 13 or the fifth group lens 5 is performed. Thus, the first cam frame 8, the second
The cam ring 15 and zoom ring 3 and distance ring 2
In this case, the rear focus can be realized with a simple configuration. As is apparent from the above description, according to the present invention, the second lens unit for restricting the driving of a plurality of lens units is provided .
Identify not only cam frame 2 for zooming drive
Joint for the focusing drive of the lens group
Reduction in the number of lens units for zooming
This makes it possible to handle even complex lens configurations
To simplify the body structure, and to move each lens frame
As a cam without any helicoid screw means
Cam means comprising a groove, a straight groove and a pin engaged with the groove
And the driving force required for its movement
Is small, especially in focusing drive.
A part of the cam frame, that is, the second cam frame is moved in the optical axis direction by cam means.
Only need to be moved by
The rotational torque required for lens movement is significantly reduced,
In particular, when configuring an auto-focusing zoom lens,
The load on the driving motor for focusing can be small, and
The power consumption can be reduced, and the components described above can be reduced.
Thus, it is possible to provide a zoom lens barrel that can be reduced in size and weight in conjunction with the size reduction .

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view of a zoom lens barrel showing one embodiment of the present invention. FIG. 2 is a developed view showing the zooming drive restricting member of the embodiment in an expanded manner. FIG. 3 is a diagram showing a movement locus of each lens group constituting the zoom lens. [Description of Signs] 1 Mount 2 Index ring 3 Zoom ring 5, 11, 13, 18, 20 Lens 6 Zoom fixing ring 8 First cam frame 9, 12, 17, 19 Lens frame 14 Straight key 15 Second cam Frame 15d Straight groove 16 Distance fixing ring 22 Distance ring 23 Intermediate ring 6a, 6b, 6d Straight groove 6c Cam groove 8b, 8c Cam groove 15a, 15c, 15d Straight groove 15b Cam groove 22a Cam groove 23a Long groove 8a, 9a, 12a, 16a, 17a, 19a, 23b
, 23c pin

Claims (1)

(57) [Claims] In a zoom lens barrel consisting of a plurality of lens groups, a straight groove along the optical axis and a cam groove
With a fixing ring, and with respect to the fixing ring in the optical axis direction.
The zooming operation member, which is rotationally driven manually or electrically in a state where movement of the
A focusing operation member that is manually or electrically rotated while being prevented from moving in the optical axis direction, and a plurality of focusing operation members.
Each on the lens frame that holds the zooming lens group
A plurality of fixed pins and an optical axis with respect to the fixing ring;
In the state where movement in the direction is prevented, the zooming operation member is driven to rotate , and
Allowed to move in the optical axis direction of the plurality of zooming lens group for cooperation with serial pin, having an inclination with respect to the optical axis
A first cam frame having a cam groove, and a pair of the first cam frame and the first cam frame.
The first cam is allowed to move in the optical axis direction.
The frame is driven to rotate integrally by the frame,
And the cooperative action of the cam groove and the pin
To move the lens group for zooming in the optical axis direction.
A second having a cam groove having an inclination and a straight groove extending along the optical axis;
And the rotational drive of the focusing operation member.
The driving is converted into the optical axis direction driving of the second cam frame only through the focusing cam means without the intermediary of the helicoid screw means, and the second cam frame is engaged with the cam groove of the second cam frame.
Holds only the lens frame with the pin fixed to the lens frame
The zoom lens barrel for a focusing drive regulating member for moving in the optical axis direction, characterized by comprising comprises a with lenses group.