JPH1138307A - Optical device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce backlash and to decrease the time delay until the operation of a lens group by adjusting the frictional force of a transferring force limiting means at the time of driving an optical device by using a power transmission mechanism. SOLUTION: A friction plates 39, 40 are mutually oppositely provided between an operation ring 33 and an output cylinder 38, the friction plate 40 is movable to the output cylinder 38 in the direction of optical axis, restricted in the rotational direction and supported by a supporting plate 41 integrally rotated with the output cylinder 38. A transferring force limiting means is constituted so as to be slipped between the friction plates 39 and 40 against a load torque larger than a prescribed load torque. In this case, the prescribed friction torque is generated by adjusting the length of a spring 42. By rotating an operation ring 33 at the time of manual operation, since the friction plate 40 is slipped against the friction plate 39, driving force transferred from the operation ring 33 to the driving means is limited.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical device having a power transmission mechanism suitable for moving optical means in a photographic lens or the like used for television photography.

[0002]

2. Description of the Related Art Conventionally, in an optical device such as a photographing lens used for television photographing or the like, predetermined optical means are driven by a driving force to perform zooming, focusing, iris adjustment, filter insertion / removal, and the like.

In the case of a photographic lens for television photographing, for example, driving of a lens group is generally performed by rotating an operation ring directly provided on the lens group, provided on an exterior surface of the lens group. The operation ring is driven manually or electrically by a cameraman according to the shooting state. To electrically drive the operation ring, a drive unit is provided in a part of the lens barrel.

The drive unit has various switches, an electric motor, and a power transmission mechanism for connecting the electric motor to an operation ring of the lens barrel. The electric motor is driven by a switch operation of a cameraman, and the power transmission mechanism is driven. The operation ring is driven by the control ring. When a predetermined lens group is manually driven, the operation ring is directly rotated by a photographer's hand, or a lever provided on the operation ring is operated to rotate.

As described above, since the operation ring of the photographing lens is driven by two methods, manual and electric, the power transmission mechanism in the drive unit has a structure that can be selectively switched according to two operation modes. ing.

FIG. 6 is an external view of a conventional photographing lens.
Lens body 1, drive unit 2, focus ring 3,
It comprises a zoom ring 4 and an iris ring 5. FIG. 7 shows a television camera equipped with such a taking lens.

FIG. 8 shows a power transmission path when a predetermined lens group is driven by the electric motor 10 in the drive unit 2. Elements other than the lens barrel and the operation ring 11 are built in the drive unit 2. On the outer peripheral surface of the operation ring 11 for driving the lens, meshing teeth 11a are provided in the circumferential direction. The electric motor 10 includes a transmission 12
Are provided integrally, and the output shaft 13 of the transmission 12 is provided.
, A sleeve 14 is fixed by a pin 15. The output gear 16 of the transmission 12 is rotatably mounted on the sleeve 14 and has a sliding washer 17.
Is pressed toward the sleeve 14 by the spring 18.

[0008] This structure, under a predetermined load torque,
The output gear 16 and the output shaft 13 rotate integrally. However, when the load torque becomes excessive, the sleeve 14 slides on the output gear 16 to reduce the force acting on the tooth surface and prevent a tooth loss. Plays the role of. This torque limiter mechanism is particularly effective in absorbing the impact force applied to the tooth surface on the stop surface when the lens group is driven to the operating end at a high speed.

An intermediate gear 19 is provided between the output gear 16 and the operation ring 11. The intermediate gear 19 is rotatable with respect to a shaft 20 holding the intermediate gear 19 and, at the same time, slides on the shaft 20. It is possible. The meshing teeth 19 a on the outer peripheral surface of the intermediate gear 19 are engaged with both the output gear 16 and the meshing teeth 11 a of the operation ring 11.

In such a power transmission mechanism, when a photographer operates a predetermined operation switch provided on the drive unit 2, the rotational power generated by the drive motor 10 is transmitted via the output gear 16 and the intermediate gear 19 of the transmission 12. And the lens group connected to the operation ring 11 is electrically driven.

FIG. 9 is a block diagram showing a case where the operation ring 11 is driven manually. In this case, the photographer rotates the clutch plate 21 by operating a clutch lever (not shown). The switching pin 22 attached to the clutch plate 21 is engaged with the intermediate gear 19 as shown in FIG.
Slides leftward on the shaft 20 and is disengaged from the engagement of the output gear 16. When the lens group is manually operated, the clutch lever is operated to cut off the power transmission path to the drive motor 10 and the operation ring 11 is manually operated directly or provided on the operation ring 11. Operate the lever to drive the lens group.

When selectively switching between electric drive and manual drive to drive the lens group, the position of the intermediate gear 19 located between the output gear 16 and the operation ring 11 and meshing with both. Is displaced to engage and disengage the meshing teeth 19a. Meshing teeth 19 at this time
a is generally provided on the outer peripheral surface as represented by a spur gear.

Further, a power transmission member for transmitting power by meshing teeth and a torque limiter member for limiting transmission torque during overload rotation to prevent loss of the tooth surface are provided by the drive motor 1.
In the power transmission mechanism that connects the lens group 0 and the operation ring 11 of the lens group, they are independently provided as separate members.

[0014]

However, in an optical apparatus having such a conventional power transmission mechanism, when a predetermined lens group in a photographing lens having a power transmission mechanism is driven electrically, an electric motor 10 is required. The intermediate gear 19 located between the output gear 16 and the operation ring 11 meshes with the output gear 16 from the electric motor 10 and the two gears of the operation ring 11.

Generally, since there is a backlash in the meshing portion of the gear, there is a time delay from when the electric motor 10 is started to when the operation ring 11 is driven. When the electric motor 10 is driven at high speed and the operation ring 11 is driven to rotate instantaneously, the time delay at this time does not pose a serious problem in practical use. In some cases, the time delay between when the cameraman issues a command to drive the lens group and when the lens group starts operating becomes a serious problem, and there is a problem that the photographing screen intended by the cameraman may not be obtained. .

Therefore, when driving the lens group,
It is desired to minimize the backlash of the gear train from the electric motor 10 to the operation ring 11. Further, since the electric drive and the manual drive are selectively switched by operating the clutch lever, the switching takes time and the operability is not always good. Furthermore, since the torque limiter member that limits the transmission torque during overload rotation and the power transmission member that transmits power by meshing the gears are each configured independently around the lens barrel as separate members, This requires a large number of components and occupies a large amount of space in the drive unit, and the drive unit is becoming complicated, which is a barrier to miniaturization and cost reduction.

An object of the present invention is to provide a power transmission mechanism for manually driving an operation ring to drive optical means held in a housing or transmitting rotational power generated by an electric motor to the optical means. An object of the present invention is to provide an optical device that reduces backlash by appropriately configuring a power transmission mechanism and reduces a time delay until a lens group operates when driven by using the power transmission mechanism.

Another object of the present invention is to enable the lens group to be driven manually and electrically without requiring a special operation for switching between electric and manual driving as in the prior art. The present invention provides an optical device capable of simplifying the structure of a torque limiter mechanism for restricting the size, simplifying and reducing the size and simplification of the entire device, and arbitrarily varying its transmission torque, and thereby varying the operation torque during manual operation. It is in.

[0019]

An optical device according to the present invention for achieving the above object is provided with a manual operation means for connecting to an optical means held in a housing and manually driving the optical means; A drive system for transmitting the driving force from the driving means to the manual operating means via the transmitting force limiting means to drive the optical means, wherein the transmitting force limiting means is configured to control the manual operating means and the drive An optical device that is integrally connected to the driving system by frictional force, and wherein a driving force transmitted from the manual operation means to the driving system is limited by the transmission force limiting means. A frictional force adjusting means for adjusting the frictional force of the limiting means.

An optical apparatus according to the present invention for achieving the above object is provided with a manual operating means for connecting to a driven member held in a housing and manually driving the driven member, and the manual operating means. A driving system for transmitting a driving force from a driving unit to drive the driven member, wherein a first member provided in the driving system and a first member provided in the manual operation unit are provided. A second member facing the first member, pressing means for bringing the first and second members into contact with each other to apply a frictional force between the first and second members, A pressing force varying means for varying a pressing force by a pressing means, wherein when the driving system is operated, the driven member is driven in a state where the first and second members are connected to each other, and the manual operation is performed. When the operating means is operated, the second member Wherein the slides relative to the first member so as to drive the driven member

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the embodiments shown in FIGS. FIG. 1 is a configuration diagram of the first embodiment, in which a friction clutch, a worm gear, and a DC motor are used as transmission force limiting means for a focus unit. A base barrel 32 is connected to the lens base 31 by a screw, and a focusing operation ring is provided on the outer periphery of the base barrel 32 as manual operation means that is manually driven. Also, the base barrel 32
A focus lens barrel 35 holding a focus lens 34 is joined to the inner periphery of the lens through helicoid screws 32b and 35a.

A focus operation ring 33 as a manual operation means has a fitting portion in the base lens barrel 32 and is freely rotatable. A photographer manually operates through the operation ring 33. Also, the operation ring 33
Is connected to a position sensor 36 composed of an encoder or a potentiometer via a gear 33a.

The connecting pin 37 for transmitting the rotational force of the operation ring 33 to the focus lens barrel 35 is connected to the focus lens barrel 3.
5, and the connection pin 37 is fitted into a cam hole 33 b provided in the operation ring 33. In response to the rotation of the operation ring 33 manually or electrically, the focus lens barrel 35 can move smoothly in the optical axis direction via the helicoid screws 32b and 35a.

An output tube 38 having a fitting portion on the lens base 31 and the base lens barrel 32 supports a part of the transmission force limiting means so that it can rotate freely, and is provided with a worm wheel 38a. .

Between the operation ring 33 and the output cylinder 38,
Friction plates 39 and 40 as transmission force driving means are provided facing each other. The friction plate 40 is movable in the optical axis direction with respect to the output cylinder 38 and has a restriction in the rotation direction as shown in FIG. The support plate 41 is supported by a support plate 41 which rotates integrally with the support 38. The support plate 41 supports a spring 42 as a pressing means for generating a frictional force, a pressing force adjusting ring 43 supporting the spring 42 and adjusting the spring length, It is pushed in by a screw 38 b provided in the cylinder 38. Reference numeral 44 denotes a nut for fixing the position of the pressing force adjusting ring 43, and serves as a double nut.

Each of the friction plates 39 to the nuts 44 has a ring shape or a substantially ring shape coaxial with the optical axis extending in the circumferential direction of the housing, and is arranged on the periphery of the lens base 31 around the optical axis. Are located in As a result, the space is effectively used, and the overall size of the apparatus is reduced. In addition, the system of the transmission force limiting means is directly connected without passing through a gear or the like so as to prevent the occurrence of a peak due to backlash or the like and the occurrence of time delay.

The transmission force limiting means is used for transmitting the driving force from the worm 45 attached to the driving means comprising an electric motor to the operation ring 33 via the worm wheel 38a and the output cylinder 38. The transmission force limiting means is configured to slip between the friction plates 39 and 40 for a load torque larger than a predetermined load torque. A predetermined friction (friction) torque can be generated by adjusting the spring length of the spring 42. The friction torque is determined by the friction coefficient of the friction plates 39 and 40 or the selection of a material.

Further, in order to improve the feeling of manual operation of the operation ring 33, a viscous fluid such as grease can be applied to a sliding portion between the friction plates 39 and 40.

When the operation ring 33 is driven by the driving means, the output from the electric motor which is a driving source and the worm 45 is transmitted to the operation ring 33 via the worm wheel 38a, the output cylinder 38 and the transmission force limiting means. You. Then, the rotation of the operation ring 33 is transmitted to the focus lens barrel 35 via the connection pin 37 penetrating the cam hole 33b. As a result, the focus lens barrel 35 is moved in the optical axis direction by the helicoid screws 32b and 35a, thereby performing focus adjustment.

When the operation ring 33 is rotated in the case of manual driving, the friction plate 40 slips with respect to the friction plate 39, so that the driving force transmitted from the operation ring 33 to the driving means is limited. That is, since the worm gear including the worm 45 and the worm wheel 38a is set so as not to be capable of back driving, the worm gear slips between the friction plate 39 and the friction plate 40, and the focusing operation with a good feeling can be performed. Further, by rotating the pressing force adjusting ring 43, the length of the spring 42 can be changed and the pressing force can be set arbitrarily.

Further, even when a force is externally applied to the operation ring 33 during the electric drive, the transmission force limiting means does not transmit a load torque exceeding a predetermined load torque, so that no excessive force is applied to the mechanical system. As a result, in the present embodiment, a mechanism for switching between electric driving and manual driving is not required, and the focus lens 34 can be selectively driven manually or electrically while simplifying the mechanism.

In this embodiment, the torque required to drive the members from the transmission force limiting means to the focus lens 34 is T _L , and the limit torque that can be transmitted by the transmission force limiting means is T _F, and T _L <T _F And the worm gear including the worm 45 and the worm wheel 38a is configured not to rotate from the worm wheel 38a side. When it is attempted to rotate from the worm wheel 38a side, when the limit torque at which the worm gear can hold the stopped state is T _M ,
T _M can be set to be greater than T _F or to infinity.

It should be noted that the torque _TL fluctuates due to fluctuations in conditions such as environmental conditions and the rotational speed of the manual operating means, and the torque _TF
And T _M fluctuate due to fluctuations in conditions such as environmental conditions, it is necessary to set each element so that the above inequality holds over a predetermined range of these fluctuations in conditions. Thereby, the drive switching between manual and electric can be performed without any special switching operation. In the case of manual operation, the operation ring 33 is operated by the operation torque of _TL + _TF.
Is rotating.

As described above, according to the first embodiment, when the operating ring 33 is driven electrically, the rotational torque of the driving means can be reliably transmitted to the driven side. By using a mechanism such as a worm gear that cannot perform a back drive, the operation torque of the operation ring 33 is determined by the rotation torque of the friction torque generated by the transmission force limiting unit and the operation torque associated with the movement of the focus lens 34. .

As a result, not only a stable rotation torque of the transmission force limiting means can be obtained, but also a desired rotation torque can be obtained by changing the length of the spring 42. Further, the driving means can be protected against overload and reverse driving on the driven side. The structure of the operation ring 33 is very simple and does not require much space.
Can be placed in the vicinity of the device, which helps to reduce the size and cost. Further, by using the worm gear, compared to the case of using a gear train, the space can be used effectively, and the effects such as the backlash can be reduced as much as possible and the responsiveness is very good can be obtained.

In the above embodiment, the case where the worm gear is used to prevent reverse rotation has been described.
For example, a speed reducer having a high reduction ratio with multiple stages of planetary gears, spur gears, etc., a speed reducer that applies biasing force to gears to reduce or minimize backlash, or a speed reducer having a differential mechanism As a result, a reduction gear having a very large reverse rotation torque can be used.

FIG. 3 shows a second embodiment, in which a transmission force limiting means and an ultrasonic motor are used in the focus unit.
The same reference numerals as in the first embodiment denote the same members. Three linear cams 52a parallel to the optical axis are provided on the outer periphery of the lens base 51 and the base barrel 52. A focusing operation ring 53 as a manual operation means is engaged with the linear cams 52a, and the operation ring 53 Is provided with a pressing force adjusting hole 53a. The focus lens 34 is held by a focus barrel 54, and the focus barrel 54 engages with a linear cam 52a of a base barrel 52 at the outer periphery thereof.
Further, it is engaged with the curved cam 53b of the operation ring 53 via three directly connected pins 55. And the focus lens barrel 5
4 corresponds to the rotation of the operation ring 53 manually or electrically,
The connection pin 55, the cam 52a of the base lens barrel 52, and the curved cam 53b of the operation ring 53 enable smooth movement in the optical axis direction.

The drive unit base 56 includes a stator 5
7. An ultrasonic motor including a rotor 58 is provided to generate a rotational force. A disc spring 60 is arranged between the stator 57 and the nut 59, and the stator 5
A suitable frictional force is generated between the rotor 7 and the rotor 58. The vibration of the rotor 58 is not transmitted to the drive transmission system by the rubber cushion 61 interposed between the stator 57 and the disc spring 60.

Further, the disc spring 6 is attached to the drive unit base 56.
0 so that the pressing force by 0 does not affect the transmission system.
2 is mounted so as to be able to rotate smoothly using a ball race 63, and an operation ring 53 is mounted on the base barrel 52 so as to be able to rotate smoothly using a ball race 64, and the base barrel 52 and the lens The base 51 has a loose fitting portion.

As in the embodiment shown in FIG. 1, a transmission force limiting means comprising a friction plate 39, a friction plate 40, and a spring 42 for generating a friction force is used as a transmission system. Further, by rotating the pressing force adjusting ring 65, the length of the spring length 42 can be changed, the pressing force can be arbitrarily set, and the nut 66 can be fixed. Reference numeral 67 denotes a cover for hiding the adjustment ring setting hole, and reference numeral 68 denotes a fixing screw for the cover. The output member 69 to the transmission force limiting means provided with the friction plate 40 is fitted into the output cylinder 62 and regulates the rotation direction using the pin 70 in order to fit the surfaces of the friction plate 39 and the friction plate 40. The output member 69 is rotated by the driving unit using the vibration wave, and the operation ring 53 is rotated via the transmission force limiting unit. This rotation is transmitted to the focus lens barrel 54 via the connection pin 55, and the focus lens 34 moves. The position sensor 36 is connected to the operation ring 53 via a gear 53c.

The stator 57 constituting the ultrasonic motor is
A piezoelectric ceramic having a property of extending and contracting in one direction for applying a voltage is bonded to a bottom surface of a ring-shaped member having a trapezoidal cross section, and an upper portion is provided with extremely regular projections. Further, the rotor 58 is pressed against the stator 57 with a certain force by a ring having a flange shape having a spring property at a contact portion with the stator 57.

In this embodiment, the stator 57 which is an elastic body is used.
A vibration is generated on the surface of the rotor 58, and the rotor 58 that has been brought into pressure contact with the stator 57 is continuously rotated by the vibration energy. The features of this driving means are that the structure is extremely simple, the responsiveness and controllability of starting and stopping are high, the operation sound is very quiet, and the holding torque for holding the stopped state at the time of stopping is large. No.

The disc spring 60 generates a pressing force for bringing the rotor 58 into pressure contact with the stator 57, but a ball race 63 is provided to offset this force, thereby affecting the transmission system. Has no effect. In addition to the supporting method, although not shown, a structure using a thrust bearing or a radial bearing can be applied. Here, it is also conceivable to use the disc spring 60 of the vibration wave motor as the pressing means which is a part of the transmission force limiting means.

When the operation ring 53 is rotated in the case of manual driving, the driving force transmitted from the operation ring 53 to the driving means by the slip torque between the friction plates 39 and 40 is limited. Since the driving unit using the vibration wave requires a large torque for the back drive, the friction plate 39 of the transmission force limiting unit slips with respect to the friction plate 40, and a comfortable focusing operation is performed.

Further, even when a force is applied to the operation ring 53 from the outside during the electric drive, the transmission force limiting means does not transmit a load torque exceeding a predetermined load torque, so that no excessive force is applied to the mechanical system. As a result, in the present embodiment, the focus lens 34 can be selectively driven manually or electrically, without the need for an electric or manual drive switching mechanism, while simplifying the mechanism.

In this embodiment, the torque required to drive the members from the transmission force control means to the focus lens 34 is T _L , the limit torque that can be transmitted by the transmission force restriction means is T _F , and the drive including the drive means The limit torque at which the system can maintain a stopped state against the driving force from its output side is T _M
, Each element is set so as to satisfy T _L <T _F <T _M. When the vibration wave driving means is used, the large holding torque of the above-described ultrasonic motor is limited to the limit torque T.
_Since it can be set so as to greatly contribute to _M , there is an advantage that it is not necessary to add a special reverse rotation restricting means, that is, a means for restricting rotation of the driving system from the output side, to the driving system including the driving means.

Note that the torque _TL fluctuates due to fluctuations in conditions such as the environmental conditions and the rotational speed of the manual operation means, and the torque T _F
And when the torque T _M fluctuates due to fluctuations in conditions such as environmental conditions, it is necessary to set each element so that the above inequality is satisfied over a predetermined range of these fluctuations in conditions. Thereby, the drive switching between manual and electric can be performed without any special switching operation. In the manual operation, the operation ring 53 is rotated by the operation torque of the torque _TL + the torque _TF .

As described above, according to the present embodiment, when the operation ring 53 is driven electrically, the rotational torque of the driving means can be reliably transmitted to the driven side. By using a large torque required for back drive such as an ultrasonic motor,
The operating torque of the operating ring 53 is determined by the rotational torque of the friction torque generated by the transmission force limiting unit and the operating torque associated with the movement of the focus lens 34.

In the prior art, if the photographing lens is tilted, the focus lens 34 may move by its own weight. However, as in the previous embodiment, a worm gear which cannot be back-driven may be used. By using a driving means or the like which requires a large torque for the back drive such as an ultrasonic motor as described above, this own weight movement can be prevented or reduced.

FIG. 4 is a block diagram of the third embodiment, in which the same reference numerals as those in the previous embodiment denote the same members. For the zoom section, a transmission force limiting means, a worm gear, and a DC motor are used, and a zoom operation ring 71 as a manual operation means is provided on the outer periphery of the lens base 31. The operation ring 71 is fitted to the lens base 31. It has a joint and can rotate freely.

In order to transmit the rotational force of the operation ring 71 to the cam ring 72, a direct connection pin 73 is provided. The direct connection pin 73 is attached to the cam ring 72 and is inserted into a cam hole 71a provided in the operation ring 71. It is inserted. The cam ring 72 can smoothly move a lens group 74 including a variator lens unit and a compensator lens unit in the optical axis direction according to the rotation of the operation ring 71 manually or electrically. Further, a DC motor as a driving source is connected to a transmission force limiting means similar to the first and second embodiments via a worm gear including a worm 75 and a worm wheel 76. The transmission force limiting means is provided between the worm wheel 76 and the operation ring 71,
As in the second embodiment, the motor is configured to slip with respect to a load torque larger than a predetermined load torque.
Further, a position sensor 77 is connected to the operation ring 71 via a gear 71b.

In the above configuration, when the operating ring 71 is driven by the driving means, the output from the DC motor as the driving source and the worm 75 is transmitted as the rotational force of the worm wheel 76 via the transmitting ring limiting means. The rotation is transmitted to the cam ring 72 via the connecting pin 73. As a result, the lens group 74 having an engaging member that engages with the linear cam provided on the lens base 31 and the curved cam provided on the cam ring 72 moves in the optical axis direction,
Magnification adjustment is performed.

When the operation ring 71 is rotated in the case of manual driving, the transmission mechanism using the worm gear is configured so as not to be able to perform the back drive, thereby causing a slip in the transmission force limiting means. The rotation of the operation ring 71 drives the lens group 74 and performs zoom adjustment in the same manner as in the case of electric operation. In addition, even when a force is applied to the operation ring 71 from the outside during the electric driving, if the torque exceeds a predetermined torque, a slip occurs in the transmission force limiting means, so that no excessive force is applied to the mechanical system. As a result, in the present embodiment, the lens group 74 can be selectively driven manually or electrically without the need for an electric / manual switching mechanism, while simplifying the mechanism.

As described above, according to the third embodiment, when the operating ring 71 is driven electrically, the rotational torque of the driving means can be reliably transmitted to the driven side. If a worm gear or the like that cannot perform back drive is used as the transmission means of the rotation torque of the drive means, the operation torque of the operation ring 71 will be the rotation torque generated by the transmission force limiting means and the operation associated with the lens movement of the lens group 74. Determined by the torque.

FIG. 5 is a block diagram of the fourth embodiment, wherein a transmission force limiting means and an ultrasonic motor are used for a zoom unit. Note that the same reference numerals as those in the previous embodiment indicate the same members. A zoom operation ring 81 as a manual operation means is provided on the outer periphery of the lens base 51. The operation ring 81 has a fitting portion on the lens base 51 and can be freely rotated.

A direct connection pin 82 is provided for transmitting the rotational force of the operation ring 81 to the cam ring 72.
Is attached to the cam ring 72 and the operation ring 81
Is inserted into the cam hole 81a provided in the cam hole 81a. Cam ring 7
2 according to the rotation of the operation ring 81 manually or electrically,
The lens group 74 can be moved smoothly in the optical axis direction. Further, a regulating pin 83 is provided to regulate the rotation of the ultrasonic motor, and the whole is covered by covers 84 and 85.

Transmission force limiting means similar to that of the previous embodiment is interposed between the output member 86 of the ultrasonic motor and the operation ring 81 so as to slip with respect to a load torque larger than a predetermined load torque. ing. Also, the gear 81b
The position sensor 77 is connected to the operation ring 81 via.

With such a configuration, when the operating ring 81 is driven by the driving means, the output from the ultrasonic motor including the stator 57 and the rotor 58 as the driving source is transmitted as the torque of the output member 86 as the transmission force. It is transmitted to the operation ring 81 via the restricting means. Then, the rotation is transmitted to the cam ring 72 via the direct connection pin 82, and the lens group 74 having an engagement member that engages with the linear cam provided on the lens base 51 and the curved cam provided on the cam ring 72.
Moves in the optical axis direction, and zoom adjustment is performed.

When the operation ring 81 is rotated for manual zoom adjustment, the ultrasonic motor requires a large torque for the back drive, so that a slip occurs in the transmission force limiting means. Further, even if a force is applied to the operation ring 81 from the outside during the electric driving, if the torque exceeds a predetermined torque, a slip occurs in the transmission force restricting means, so that no excessive force is applied to the mechanism. As a result, in the present embodiment, the mechanism is simplified while not requiring an electric / manual switching mechanism.
The lens group 74 can be selectively driven manually or electrically.

As described above, according to the fourth embodiment, when the operating ring 81 is driven electrically, the rotational torque of the driving means can be reliably transmitted to the driven side. For example, by using an ultrasonic motor or the like having a large torque required for the back drive as the driving means, the operating torque of the operating ring 81 is reduced by the rotational torque generated by the magnetic coupling means and the operating torque caused by the lens movement of the lens group 74. Is determined by

In the above-described embodiment, a spring has been described as an example of a pressing means for generating a frictional force. Elastic members can also be used. Further, it may be configured to press with a member having no elasticity.

[0062]

As described above, according to the optical device according to the present invention, the operation ring is manually driven to drive the optical means held in the housing, or the rotational force generated by the electric motor is transmitted to the optical device. When driving using a power transmission mechanism that transmits power to the means, the optical means can be driven manually and electrically, without any special operation for switching between electric and manual driving, and backlash is reduced. In addition, the time delay until the lens operates can be reduced, and further, the structure of the torque limiter mechanism that limits the transmission torque during overload rotation is simplified, and the size and simplification of the entire device are achieved, and the transmission torque Can be arbitrarily changed, and thereby the operating torque at the time of manual operation can be changed.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of a first embodiment.

FIG. 2 is a configuration diagram of a fitting state between an output cylinder and a support plate.

FIG. 3 is a sectional view of a main part of a second embodiment.

FIG. 4 is a sectional view of a main part of a third embodiment.

FIG. 5 is a sectional view of a main part of a fourth embodiment.

FIG. 6 is an external view of a conventional photographing lens.

FIG. 7 is a configuration diagram of a video camera to which a photographing lens is attached.

FIG. 8 is a configuration diagram of a main part of a lens barrel.

FIG. 9 is a configuration diagram of a main part of a lens barrel.

[Explanation of symbols]

 31, 51 Lens base 32, 52 Base lens barrel 33, 53 Focusing operation ring 34 Focus lens 35, 54 Focus lens barrel 36, 77 Position sensor 38, 62 Output cylinder 38a, 76 Worm wheel 39, 40 Friction plate 42 Spring 43 , 65 Pressing force adjusting ring 44, 66 Nut 45, 75 Worm 56 Drive unit base 57 Stator 58 Rotor 69 Output member 74 Lens group 71, 81 Zoom operation ring

Claims (19)

[Claims] 1. A manual operating means connected to an optical means held in a housing for manually driving the optical means, and a driving force from the driving means to the manual operating means via a transmission force limiting means. A drive system for transmitting and driving the optical unit, wherein the transmission force limiting unit integrally couples the manual operation unit and the drive system by frictional force, and An optical device configured such that a driving force transmitted to a driving system is limited by the transmission force limiting unit, wherein the optical device includes a frictional force adjusting unit that adjusts the frictional force of the transmission force limiting unit. Optical device. 2. The transmission force limiting means includes: a pair of opposing members opposing each other; and a contact force between the pair of opposing members to apply a frictional force between the pair of opposing members. The optical device according to claim 1, further comprising a pressing unit for pressing the optical device. 3. The optical device according to claim 2, wherein said frictional force adjusting means is a pressing force adjusting means for adjusting a pressing force of said pressing means. 4. The pressing means has an elastic member for pressing one of the opposing members toward the other of the opposing members, and a supporting member for supporting the elastic member. 4. The optical device according to claim 3, further comprising a support member displacing means for displacing the support member so as to change its elastic force by deforming the support member. 5. The optical device according to claim 4, further comprising a support member fixing means for fixing a position of the support member. 6. The optical device according to claim 1, wherein the pair of opposing members is annular. 7. The optical device according to claim 1, wherein the pair of opposing members is formed in an annular shape substantially coaxial with an optical axis. 8. The optical device according to claim 2, wherein a viscous fluid is interposed between said pair of opposed members. 9. The optical device according to claim 1, wherein the driving unit is a vibration wave driving unit. 10. The driving system may transmit a driving force from the driving unit to the transmission force limiting unit, and may be driven by a driving force transmitted from the manual operation unit via the transmission force limiting unit. The optical device according to any one of claims 1 to 8, wherein the optical device has no driving force transmitting means. 11. The worm gear comprising a worm and a worm wheel.
The optical device according to 0. 12. The optical device according to claim 11, wherein the worm wheel is coupled to an opposing member on the drive system side of the pair of opposing members. 13. The torque required for driving the member on the optical means side from the transmission force limiting means without including the transmission force limiting means is _TL , and the limit torque that can be transmitted by the transmission force limiting means is _TF , Each element is set so as to satisfy T _L <T _F <T _M , where T _M is a limit torque at which the drive system can hold a stop state with respect to a drive force from the output side. The optical device according to claim 12. 14. The optical device according to claim 1, wherein the optical device is a lens barrel. 15. The optical device according to claim 1, wherein said optical means is a lens.
The optical device according to claim 1. 16. The optical device according to claim 15, wherein the lens is movable along an optical axis. 17. The optical device according to claim 15, wherein the lens is a focus lens. 18. The optical device according to claim 15, wherein the lens is a variable power lens. 19. A manual operation means connected to a driven member held in a housing and manually driving the driven member, and a driving force transmitted from the driving means to the manual operation means to transmit the driving force to the manual operation means. An optical device having a drive system for driving a drive member, a first member provided in the drive system, a second member provided in the manual operation means and opposed to the first member, and Pressing means for bringing the first and second members into contact with each other to apply a frictional force between the first and second members, and pressing force varying means for changing the pressing force by the pressing means; When the drive system is operated, the driven member is driven in a state where the first and second members are connected to each other, and when the manual operating means is operated, the second member is The driven member slides with respect to a first member. An optical device characterized in that the optical device is driven.