JPH09105849A - Photographing lens driving device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform variable power operation and focusing operation by a single power source by slidably providing a gear member having two gears on the output shaft of a single motor and moving it between a position where one gear is meshed with a gear connected to a driving member for variable power driving which makes a photographing lens perform the variable power operation and a position where the other gear is meshed with a gear connected to a driving member for focusing driving which makes the lens perform the focusing operation by the sliding of the gear. SOLUTION: A variable power driving transmitting gear 24b is formed at the leading end of a zoom cam barrel 211 having cam holes 24C and 24d which make a front group lens 21 and a rear group lens 22 advance and retreat in an optical axis direction to perform variable power operation, and a focusing driving transmitting gear 30b is formed at the leading end of a focusing gear 30 which makes the front group lens 21 advance and retreat in the optical axis direction to perform focusing operation. The gear member 36 slidably provided on the output shaft 35a of the motor 35 is equipped with a variable power driving gear 36a and a focusing driving gear 36b. The combination of the meshing gears 24b, 36a, 30b and 36b is changed by the sliding of the gear, so that the variable power operation and the focusing operation are switched.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving device for a photographing lens, such as a video camera, having zooming and focusing functions.

[0002]

2. Description of the Related Art In an image pickup apparatus having functions of zooming and focusing, the position for setting a subject is almost constant, so that the zooming optical system is moved to a predetermined position by setting the magnification. A motor for driving the variable power optical system is provided. Further, it is necessary to drive the focusing optical system after being driven by the variable power, and a motor is also provided for driving the focusing optical system. It should be noted that an image pickup apparatus equipped with a zoom lens using pan focus only needs to be provided with a motor for variable magnification drive, but the image pickup range of the object is limited within a certain range so that the image of the object is not blurred. If the distance to the subject is short, the image is out of focus, and the focus cannot be adjusted in the pan focus. Since the focus range is narrow, the focus cannot be achieved, and a desired image may not be obtained.

FIG. 6 is a view showing a driving device for a photographic lens in a conventional photographic device of this type, which is a cross-sectional view taken along a plane including an optical axis, with a part thereof omitted. In this photographing apparatus, a photographing optical system is configured by two lens groups, a front lens group 1 and a rear lens group 2, and the front lens group 1 serves as a focusing optical system. A fixed barrel 3 is attached to the main body of the apparatus, and a zoom cam barrel 4 is supported on the fixed barrel 3 so as to be rotatable around the optical axis of the taking lens. An elongated hole 3a is formed in the fixed lens barrel 3 in the optical axis direction, and the zoom cam barrel 4 is also provided.
Two kinds of cam holes are formed in the spiral shape.

The rear group lens 2 is held by a rear side moving frame 5, and a rear group driving pin 5a projecting radially on the outer peripheral portion of the rear side moving frame 5 has the long hole 3a and the zoom cam barrel 4. Is loosely inserted in one of the cam holes formed in the. The front group lens 1 is held by a front side holding frame 6, and the front side holding frame 6 is linked to a front side moving frame 8 via a focus cam barrel 7.
A front group drive pin 8a, which is provided on the outer peripheral portion of the front moving frame 8 so as to project in the radial direction, is loosely inserted into the long hole 3a of the fixed lens barrel 3 and the other cam hole formed in the zoom cam barrel. Therefore, when the zoom cam barrel 4 rotates about the optical axis, the rear group drive pin 5a is guided by the elongated hole 3a and one of the cam holes to advance and retreat in the optical axis direction by a predetermined movement amount, and the front group drive pin 5a. 8a is guided by the long hole 3a and the other cam hole to advance and retreat in the optical axis direction by a predetermined amount of movement. Therefore, if the above-mentioned two types of cam holes have predetermined shapes, the front lens group 1 and the rear lens group 2 are driven in a variable magnification while maintaining a predetermined optical relationship. A flange portion 4a is formed at the rear end portion of the zoom cam cylinder 4, and a gear is formed on the outer peripheral surface of the flange portion 4a. The pinion 9a fitted to the output shaft of the zoom drive motor 9 meshes with this gear, and the zoom cam cylinder 4 is rotated by the rotation of the zoom drive motor 9.

The front holding frame 6 is connected to the focus gear 10 via the focus cam barrel 7, and the rotation of the focus gear 10 moves the front holding frame 6 in the optical axis direction.
The front lens group 1 is made to perform a focusing operation. A gear is formed on the outer peripheral surface of the flange portion 10a formed at the front end of the focus gear 10, and the pinion 11a fitted to the output shaft of the focus drive motor 11 meshes with this gear to drive the focus drive. The focus gear 10 is rotated by the rotation of the motor 11.

[0006]

However, as described above, in the conventional driving device, since two motors for zoom driving and focus driving are used, the external shape and weight of the device are increased and the cost is reduced. It was disadvantageous in terms of reduction.

Therefore, an object of the present invention is to combine a motor for zoom drive and a motor for focus drive by one motor, thereby achieving weight reduction and size reduction as well as cost reduction. It is to provide a driving device for a photographing lens.

[0008]

As a technical means for achieving the above object, a driving device for a photographing lens according to the present invention comprises a multi-lens group, and the multi-lens group is set to a predetermined number. For zooming and focusing by moving the lens in the optical axis direction while maintaining the optical relationship of, and performing focusing by moving some lens groups in the optical axis direction. In the driving device, the power path switching means is connected to the output part of a single drive source, and a power transmission path from the power path switching means to the variable power drive member is provided, and the power path switching means is focused. A power transmission path to a drive member for driving is provided, and a switching operation of the power path switching means switches between a zooming operation and a focusing operation of the photographing lens by the drive source.

In the case of performing variable power drive, the power path switching means is switched to form a power transmission path from the drive source to the variable power drive member, and from the drive source to the variable power drive member. Power is transmitted. As a result, power is transmitted from the variable-magnification driving member to the variable-magnification optical system, and the variable-magnification operation is performed. When the variable power is completed, the power path switching means is switched from the variable power drive member to the focusing drive member to transmit the power from the drive source to the focusing drive member. As a result, the power is transmitted to the focusing optical system and the focusing operation is performed. The switching operation of the power path switching means may be performed manually or by receiving an electric signal.

Further, when the taking lens is composed of two lens groups so as to simplify the construction of the taking lens and simplify the operations of zooming and focusing, it is composed of a front lens group and a rear lens group. , A zooming operation is performed by moving the front lens group and the rear lens group in the optical axis direction while maintaining a predetermined optical relationship, and by moving one of the lens groups in the optical axis direction. In a drive device for zooming and focusing of a photographing lens that performs a focusing operation, a power path switching means is connected to an output part of a single drive source, and the power path switching means leads to a zoom driving member. A power transmission path is provided, and a power transmission path from the power path switching means to the focusing drive member is provided. By the switching operation of the power path switching means, the zooming operation and focusing of the photographing lens by the drive source are performed. And characterized by performing switching the work.

When the power transmission path is switched to reach the driving member for variable magnification driving, the front lens group and the rear lens group advance and retreat in the optical axis direction to perform the variable magnification operation. When the power transmission path is formed so as to reach the focusing drive member after the variable magnification driving is completed, only one of the front lens group and the rear lens group moves back and forth in the optical axis direction to perform the focusing operation. become.

Further, there is a structure in which a cam barrel which rotates around the optical axis of the photographing lens is used as a driving member for driving the variable power optical system and the focusing optical system, which is suitable for this structure. As the front lens group and the rear lens group are pivoted about the optical axis of the zoom cam barrel connected to the front lens group and the rear lens group, the front lens group and the rear lens group are maintained in a predetermined optical relationship to advance and retreat in the optical axis direction. The focusing lens connected to the front lens group is rotated about the optical axis to move the front lens group back and forth in the optical axis direction to perform the focusing operation. In a drive device for focusing, a power path switching means is connected to an output part of a single drive source, and a switching operation of the power path switching means causes a power transmission path from the drive source to the zoom cam barrel and the focus. gear And the power transmission path extending is characterized by switched.

Further, the drive source is constituted by a motor, and the power path switching means is constituted by a gear member having a first gear and a second gear slidably provided on an output shaft of the motor in an axial direction. The sliding of the gear member switches between a position where the first gear is connected to the zoom cam barrel and a position where the second gear is connected to the focus gear.

When both the variable-magnification driving member and the focusing driving member are constituted by cam barrels which rotate about the optical axis, the driving source outputs a rotational force like a motor. The device can be used as a device, the installation space of the drive source can be reduced, and the weight reduction can be promoted. In particular, the use of a pulse motor is preferable because the zooming operation and the focusing operation can be easily controlled.

[0015]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a driving device for a photographing lens according to the present invention.

FIG. 1 is a view showing a driving device of this photographing lens, and is a sectional view in which a part including the optical axis is cut and a part thereof is omitted. The photographing lens driven by this driving device is composed of a front lens group 21 and a rear lens group 22, which are two lens groups. A fixed lens barrel 20 is attached to an apparatus main body (not shown), and a guide hole 20a is linearly formed in the fixed lens barrel 20 along the optical axis direction of the taking lens. A pin portion 23a, which is projected in the radial direction on the outer periphery of the rear side moving frame 23 holding the rear group lens 22, is loosely inserted in the guide hole 20a.

A zoom cam barrel 24 as a variable magnification driving member is loosely fitted to the fixed lens barrel 20 so as to be rotatable about the optical axis with respect to the fixed lens barrel 20. A flange portion 24a is formed at the front end portion of the zoom cam barrel 24, and a variable power transmission gear 24b is formed on the outer peripheral surface of the flange portion 24a. The zoom cam barrel 24 has a rear group cam hole 24c formed in an appropriate shape in the spiral direction.
The pin portion 23a of 23 is loosely inserted in the rear group cam hole 24c. Therefore, when the zoom cam barrel 24 rotates, the pin portion 23
a is guided by the rear group cam hole 24c and the guide hole 20a to advance and retreat in the optical axis direction by a predetermined amount of movement, and the rear group lens 22 held by the rear side moving frame 23 has a predetermined amount of movement in the same direction. I am going to retreat.

At the tip of the guide hole 20a of the fixed lens barrel 20, there is loosely inserted a pin portion 25a projecting in the radial direction on the outer surface of the front moving frame 25. A front group cam hole 24d is formed in the zoom cam barrel 24 in an appropriate shape in the spiral direction, and the front end of the pin portion 25a is loosely inserted into the front group cam hole 24d. A front group lens frame 26 is connected to the front side moving frame 25 through a focus cam cylinder described later, and the front group lens frame 26 holds a front group lens 21 forming a photographing lens. Therefore, when the zoom cam barrel 24 rotates, the pin portion 25a is moved to the guide hole 20a and the front group cam hole 24.
The front lens group 21 held by the front lens group frame 26 linked to the front moving frame 25 moves in the same direction as the front moving frame 25 moves in the same direction by being guided by the d. Go back and forth. Therefore, the front lens group 21 and the rear lens group
22 and 22 move forward and backward in synchronization with the rotation of the zoom cam barrel 24,
By being guided by the rear group cam hole 24c and the front group cam hole 24d to move back and forth, a predetermined optical relationship is maintained and variable magnification driving is performed.

As shown in FIG. 2, a support hole 20b is formed in the front end of the fixed lens barrel 20 along the circumferential direction. A focus gear 30 as a focusing drive member is rotatably inserted and is held at the tip of the fixed lens barrel 20 by a gear support pin (not shown) penetrating the support hole 20b. As shown in FIG. 5, a flange portion 30a is formed at the tip of the focus gear 30, and a focusing drive transmission gear 30b is formed on the outer peripheral surface of the flange portion 30a. A guide groove 30c is formed on the inner peripheral surface of the focus gear 30 along the optical axis direction as shown in FIGS.

The front moving frame 25 is housed in the inner peripheral portion of the focus gear 30, and a focus cam barrel 31 rotatable around the optical axis is loosely inserted in the inner peripheral portion of the front moving frame 25. ing. On the outer surface of the tip of the focus cam barrel 31, there is a connecting pin 31a protruding in the radial direction as shown in FIG.
Has been planted. As shown in FIG. 3, a circumferential long hole 25b is formed at the tip of the front moving frame 25, and the connecting pin 31a penetrates the long hole 25b and the guide groove 30c of the focus gear 30. Is inserted into. Therefore,
When the focus gear 30 rotates, the focus cam barrel 31 in which the connecting pin 31a loosely inserted in the guide groove 30c is planted rotates about the optical axis. As shown in FIG. 4, the focus cam barrel 31 is formed with a front group lens cam hole 31b having an appropriate shape along the spiral direction. On the other hand, the front moving frame 25 is provided with an optical axis as shown in FIG. The support elongated hole 25c is formed along the direction of the above, and the drive pin 26a planted on the outer peripheral surface of the front group lens frame 26 penetrates the front group lens cam hole 34b and the support elongated hole 25c. Is inserted into.

An output shaft 35 is provided outside the tip ends of the gears 24b and 30b formed on the fixed barrel 20 and the focus gear 30.
A motor 35 as a drive source is disposed with a positioned. A gear member 36 which constitutes a power path switching means is loosely fitted to the output shaft 35a in the axial direction so as to be slidable with respect to the output shaft 35a. That is, the output shaft 35a and the gear member 36 are splines, and the output shaft 35a has a substantially D-shaped cross section.
The gear member 36 is rotated by the operation of the motor 35 and is slidable in the axial direction of the output shaft 35a by forming the boss hole of the same shape. The first end of the gear member 36 is capable of meshing with the variable power transmission gear 24b.
A variable power drive gear 36a is formed as a gear, and the other end of the variable power drive gear 36a can be meshed with the focusing drive transmission gear 30b.
Focus drive gears 36b as gears are formed at appropriate intervals. A reduced diameter input portion 36c is formed at an appropriate position in the center of the gear member 36.

In the vicinity of the gear member 36, a switching member 37 is swingable about an axis along a direction intersecting the optical axis.
Is provided. A switching arm portion 37a is provided on a part of the outer peripheral surface of the switching member 37 so as to project in the radial direction.
The tip portion of 37a is engaged with the input portion 36c of the gear member 36. A locking arm portion 37b is formed on a portion opposite to the switching arm portion 37a, and a tip end portion of a click spring 38 made of a leaf spring fixed at an appropriate position of the apparatus main body is restored by the restoring force. It is pressed against the tip of part 37b. The swing of the switching member 37 causes the gear member 35 to slide with respect to the output shaft 35a, and this sliding causes the variable power drive gear 36a of the gear member 36 to mesh with the variable power drive transmission gear 24b. , The focus drive gear 36b is the focus drive transmission gear 30
It is located either in a position meshing with b or in a position not meshing with any gear. That is, the gear member 36 and the switching member 37 constitute a power path switching means.

The operation of the photographic lens driving device according to the present invention constructed as described above will be described below.

FIG. 1 shows a state in which the photographic lens is driven in focus. When the photographic lens is driven to vary its magnification, the switching member 37 is operated to swing it clockwise in FIG. . Due to this swing, the gear member 36 slides to the left in FIG. 1, and the variable drive gear 36a meshes with the variable power transmission gear 24b formed on the zoom cam barrel 24.
Therefore, the output rotation of the motor 35 is transmitted to the zoom cam barrel 24, and the zoom cam barrel 24 rotates about the optical axis. The rotation of the zoom cam barrel 24 causes the guide hole 20a formed in the fixed lens barrel 20 and the zoom cam barrel 24 to move.
The rear group moving frame is formed by the rear group cam hole 24c formed in the
The rear lens group 22 together with the guide hole 20a and the zoom cam barrel 24
The front group moving frame is formed by the front group cam hole 24d formed in
25 and 25 respectively move in the optical axis direction by a predetermined amount of movement. The focus cam cylinder 31 is connected to the connecting pin on the front group moving frame 25.
Since the 31a and the long hole 25b are engaged with each other, the movement of the front lens group moving frame 25 causes the focus cam barrel 31 to move in the same direction and with the same movement amount. The drive pin 26a is loosely inserted in the cam hole 31b, and the front lens group frame 26, which is prevented from rotating about the optical axis, moves in the same direction and with the same amount of movement. That is, the zoom cam barrel 24
By the rotation of, the front lens group 21 and the rear lens group 22 advance and retreat in the optical axis direction while maintaining a predetermined optical relationship according to the cam shapes of the front group cam hole 24d and the rear group cam hole 24c. As a result, the scaling operation is performed.

In the state where the zooming operation is completed, the switching member
The gear member 36 is slid by operating 37. By this sliding, as shown in FIG. 1, the focusing drive gear 36b and the focusing drive transmission gear 30b mesh with each other. As a result, the output rotation of the motor 35 is transmitted to the force gear 30, and the focus gear 30
The 30 will rotate about the optical axis. When the focus gear 30 rotates, the focus cam cylinder 31 in which the connecting pin 31a engaged with the guide hole 30c formed in the inner peripheral surface is planted rotates in the same direction. A front group lens cam hole 31b is formed in the focus cam barrel 31, and a drive pin 26a protruding from the front group lens frame 26 is loosely inserted in the front group lens cam hole 31b. Since the front end of 26a is loosely inserted in the long hole 25b of the front side moving frame 25, the front lens group frame is rotated by the rotation of the focus cam barrel 31.
26 moves back and forth in the optical axis direction, and the front lens frame 26
The front lens group 21, which is held by, moves to the in-focus position. Then, when the motor is stopped, the photographic lens is in a state in which the subject image is formed on the image forming means at a predetermined magnification.

In the embodiment described above, the switching member 37 may be manually operated or rotated by using a motor.
Further, although the driving mechanism of the photographing lens constituted by the two groups of the front lens group 21 and the rear lens group 22 has been described, the photographing lens constituted by three or more groups can be driven.

[0027]

As described above, according to the photographing lens driving device of the present invention, the zooming operation and the focusing operation can be switched by a single driving source. It is possible to reduce the weight and size of the device as compared with the device mounted separately according to each operation. Further, the cost can be reduced by reducing the number of drive sources.

[Brief description of the drawings]

FIG. 1 is a diagram showing a driving device of this photographing lens, which is a cross-sectional view in which a part including the optical axis is cut and a part thereof is omitted.

FIG. 2 is a schematic perspective view of a fixed barrel that constitutes the barrel.

FIG. 3 is a schematic perspective view of a front moving frame that constitutes a lens barrel.

FIG. 4 is a schematic perspective view of a focus cam barrel that constitutes a lens barrel.

FIG. 5 is a schematic perspective view of a focus gear as a focus driving drive member that constitutes a lens barrel.

FIG. 6 is a view showing a conventional driving device for a photographing lens, which is a cross-sectional view taken along a plane including an optical axis, with a part thereof omitted.

[Explanation of symbols]

 20 Fixed lens barrel 21 Front group lens 22 Rear group lens 23 Rear side moving frame 24 Zoom cam barrel (drive member for variable magnification drive) 24b Variable magnification drive transmission gear 25 Front side moving frame 26 Front group lens frame 30 Focus gear (focus drive) Focus drive transmission gear 31 Focus cam barrel 35 Motor (drive source) 36 Gear member (power path switching means) 36a Variable drive gear (first gear) 36b Focus drive gear (second gear) 36c Input unit 37 switching member (power path switching means)

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display area // G03B 17/00

Claims (4)

[Claims] 1. A multi-lens group comprising a multi-lens group, wherein the multi-lens group is maintained in a predetermined optical relationship and moved back and forth in the optical axis direction to perform a zooming operation, and a part of the lens group In a drive device for zooming and focusing of a photographing lens that performs a focusing operation by moving in the axial direction, a power path switching means is connected to an output part of a single drive source, A power transmission path is provided to the variable-magnification drive member, and a power transmission path is provided from the power-path switching unit to the focusing drive member. The switching operation of the power-path switching unit causes the drive source to take a photographic lens. A driving device for a photographing lens, characterized in that the zooming operation and the focusing operation are performed by switching. 2. A zoom lens is constituted by a front lens group and a rear lens group, and the front lens group and the rear lens group maintain a predetermined optical relationship and are moved back and forth in the optical axis direction to perform a zooming operation. In a drive unit for zooming and focusing of a taking lens that performs a focusing operation by moving one lens group forward and backward in the optical axis direction, a power path switching unit is connected to an output unit of a single drive source. A power transmission path from the power path switching means to the variable power drive member, and a power transmission path from the power path switching means to the focus drive drive member, A driving device for a photographing lens, characterized in that the driving source switches between a zooming operation and a focusing operation of the photographing lens. 3. The optical axis of the zoom lens barrel connected to the front lens group and the rear lens group is rotated about the optical axis so that the front lens group and the rear lens group maintain a predetermined optical relationship. The zoom lens is moved in the same direction to perform the magnification change operation, and the rotation of the focus gear linked to the front lens group around the optical axis moves the front lens group in the optical axis direction to perform the focusing operation. In a drive device for zooming and focusing, a power path switching means is connected to an output part of a single drive source, and a power transmission path from the drive source to the zoom cam barrel is switched by a switching operation of the power path switching means. And a power transmission path leading to the focus gear are switched. 4. The drive source is constituted by a motor, and the power path switching means is constituted by a gear member having a first gear and a second gear slidably provided on an output shaft of the motor in an axial direction. 4. The photographing lens according to claim 3, wherein the sliding of the gear member switches between a position where the first gear is connected to the zoom cam barrel and a position where the second gear is connected to the focus gear. Drive.