JP2000147360A - Drive transmission device and lens barrel using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lens barrel capable of executing an automatic focusing operation and a manual focusing operation without affecting a motor driving part. SOLUTION: The device is provided with rotor connecting members 20 and 22 for transmitting the rotation of a rotor member 18 in frictional connection with the rotor member 18, a manual connection member 25 for transmitting the manual rotation, rollers 24 which are arranged at three or more positions on a circumference around the optical axis of the lens and also which are rotated around supporting, shafts arranged in the radial direction of the optical axis and which are rotated while being held between the manual connection member 25 and the rotor connection member 22, and an output ring 23 which is rotated while transmitting the rotation of the roller 24 around the optical axis. When a load equal to or exceeding the prescribed one by which the rotation is interrupted is applied on the output ring 23, a slippage is generated between the rotor member 18 and the rotor connection members 20 and 22 so as not to transmit the rotation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive transmission device having a built-in annular vibration wave motor and a lens barrel, for example, a drive transmission device for performing an auto-focus operation and a manual focus operation, and a lens using the same. Related to the lens barrel.

[0002]

2. Description of the Related Art Conventionally, a vibration wave for focusing is provided which has a built-in vibration wave motor so that an auto-focus operation and a manual focus operation can be performed almost continuously without a special switching operation. The applicant has proposed a lens barrel with a built-in motor, and some of the proposals have been commercialized by the applicant.

Some lens barrels proposed by the present applicant use a differential mechanism to automatically switch between an autofocus operation and a manual focus operation. This uses a planetary roller for the differential mechanism. The planetary roller has a rotation axis along a radial direction with respect to an optical axis, and a first ring from a manual ring for performing a manual focusing operation. An output ring is disposed so as to sandwich the planetary roller between an output member and a second output member from a vibration wave motor for performing an autofocus operation, and an output ring that rotates by picking up the revolution of the planetary roller is provided. A differential mechanism for the final output is configured.

A focusing lens is driven by the output ring. In particular, in a manual focusing operation, the feature of the structure of the vibration wave motor is fully utilized.

That is, as is well known, a vibration wave motor is provided with a ring-shaped metal elastic body (corresponding to a stator) on which a traveling wave is formed, the ring forming a second output member of the vibration wave motor. The rotor is pressed by a pressing member such as a spring, and the rotor is frictionally driven by a traveling wave formed in the elastic body. In the differential mechanism, the pressing force of the pressing member is applied along the optical axis direction. The pressing force of the second pressurizing member acts so that the manual ring maintains the non-rotational state even when the second output member being received rotates, and conversely, the manual ring is rotated to perform manual focusing. When performing this operation, since the vibration wave motor is in the non-energized state and the rotor is in pressure contact with the stator, the non-rotated state of the rotor is maintained, and the auto-forging is automatically performed without using any switching mechanism. Switching of the scan operation and manual focus operation are in the manner done.

A conventional embodiment will be described below with reference to FIG. 2 as an example.

FIG. 2 is a sectional view of a conventional focus drive unit. In FIG. 2, reference numeral 101 denotes a unit support cylinder for holding each component of the focus drive unit.
Reference numeral 102 denotes an annular elastic vibrating body having a trapezoidal cross section (hereinafter referred to as a stator);
2 is an electrostrictive element that is joined to one end face of the piezoelectric element 2 to vibrate.

Reference numeral 104 denotes an annular vibration absorber made of felt or the like pressed against the surface of the electrostrictive element 103;
Is a coned disc spring as a pressing means for urging the vibration absorber 104 in the optical axis direction.

Reference numeral 106 denotes a nut which is screwed into a screw portion formed on the outer diameter of the unit support cylinder 101 to adjust the pressing force of the disc spring 105. Reference numeral 107 denotes the unit support cylinder 101.
And a detent for restricting the rotation of the stator 102.

Reference numeral 108 denotes a rotating body (hereinafter referred to as a rotor) which receives a rotating force about the optical axis by the stator 102.

Reference numeral 110 denotes a connecting plate which rotates integrally with the rotor 108 via a rubber ring 109 and is brought into contact with a roller described later.

Reference numeral 111 denotes a plurality of shafts 11 extending radially with respect to an optical axis which rotatably supports a roller 112 described later.
1a, which is an output ring which is connected to a cam ring (not shown) via a focus key 115 described later to transmit a revolution about the optical axis of a roller 112 described later and transmits the rotation thereof.

Reference numeral 112 denotes a connecting plate 1 which is pivotally supported by the output ring 111.
These rollers are rolled while being sandwiched between a manual connection plate 113 and a manual connection plate 113 described later, and revolve around the optical axis.

Reference numeral 113 denotes a manual connection plate as a rotary plate to which rotation is transmitted from a focus ring (not shown).

Reference numeral 114 denotes a holding ring which is brought into contact with the manual connecting plate 113 and is fitted to the unit main body so as to restrict rotation. Reference numeral 115 denotes a focus key which is attached to the output ring 111 and is a mirror. The cylinder is driven.

[0016]

However, in the above proposal, when the rotation of the output ring is restricted (when it hits the infinite end or the closest end), when the focus ring is further turned, The rotation must slip and absorb the rotation between the manual connecting plate 113 and the roller 112, between the roller 112 and the connecting plate 110, or somewhere between the rotor 108 and the stator 102. This is a place where rotation is transmitted by friction during AF and manual operation, and where wear due to slippage leads to deterioration of the performance of AF and manual.

An object of the invention according to the present application is to prevent transmission of a driving force between a manual operation and an automatic operation so that the performance of the manual driving unit and the automatic driving unit is not deteriorated. And a lens barrel using the same.

[0018]

In order to achieve the object of the present invention, a driving force from a manual driving unit is inputted to a first input member, and a driving force from a motor driving unit is inputted to a second input member. In a drive transmission device that receives a force and has a differential transmission unit that drives an output member by a differential operation between the first input member and the second input member, the motor drive unit includes: A drive transmission device is provided with friction clutch means for interrupting transmission of a predetermined or more drive force from the input member side to the motor.

Further, the friction clutch means includes a first connecting member frictionally connected to the motor driving section, a second connecting member frictionally connected to the driven member, and a first connecting member and the second connecting member. And a friction plate sandwiched therebetween.

Further, the motor is a vibration wave motor for bringing a rotating body and a vibrating body into pressure contact with each other, and the friction clutch means disposed between the rotating body of the vibration wave motor and the second input member. It is characterized by having.

The differential transmission means is constituted by a differential mechanism in which a planetary roller is rotatably supported by an output member and rolls while being sandwiched between a first input member and a second input member. It is characterized by having.

According to the above construction, even when the manual drive unit is driven when the rotation of the output member is restricted, the rotational force of the friction clutch means between the driven member and the motor drive unit is maintained. By absorbing the slip, no slip occurs between the manual drive unit and the driven member, between the driven member and the friction clutch unit, or between the motor drive unit and the friction clutch unit. No effect.

On the other hand, a manual driving unit for inputting a driving force to the first input member by manual operation and driving the lens by differential transmission means, and a motor driving force for inputting the motor driving force to the second input member. A lens drive unit having a motor drive unit for driving a lens by a transmission unit, wherein the motor drive unit is provided with friction clutch means for blocking transmission of a predetermined or more drive force from the first input member side to the motor. Is provided in the lens barrel.

Further, the friction clutch means includes a first connecting member frictionally connected to the motor driving section, a second connecting member frictionally connected to the driven member, and a first connecting member and a second connecting member. And a friction plate sandwiched therebetween.

The motor is a vibration wave motor for bringing a rotating body and a vibrating body into pressure contact with each other, and the friction clutch means disposed between the rotating body of the vibration wave motor and the second input member. It is characterized by having.

Further, the differential transmission means is constituted by a differential mechanism in which a planetary roller is rotatably supported by an output member and rolls while being held between a first input member and a second input member. It is characterized by having.

According to the above-described configuration, when the rotation of the output member is restricted in the lens barrel that can be automatically switched between the auto focus operation and the manual focus operation as the auto operation and the manual operation, for example. Even when the manual drive unit is driven, the rotational force is absorbed by the sliding of the friction clutch means between the driven member and the motor drive unit, so that the manual drive unit and the driven member can be driven. There is no slippage between the motor and the friction clutch means or between the motor drive unit and the friction clutch means, so that it is possible to provide a lens barrel having no influence on the motor drive unit side.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) A first embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of a lens barrel using a drive unit according to the present embodiment. Reference numeral 1 denotes a focusing lens group, 2 denotes a fixed lens group, and 3 denotes a first group lens barrel that holds the focusing lens group 1 and includes a driving cylinder 3a that engages with a guide cylinder 5 and a cam ring 6 described below. .

Reference numeral 4 denotes a second lens barrel for holding the above-mentioned fixed lens group 2, which is integrally held by a guide cylinder 5 described later.

Reference numeral 5 denotes a guide tube for supporting the first lens barrel 3 so as to be slidable in the direction of the optical axis. It has a rectilinear groove 5b with which the driving roller 3a is engaged.

Reference numeral 6 denotes a cam 6a which is rotatably engaged with the guide tube 5 by the above-mentioned pawl 5a, and has a cam 6a to which the driving roller 3a of the above-mentioned first group lens barrel 3 is engaged. This is a cam ring having a projection 6b for engaging with the holding ring 26 of the unit and transmitting rotation.

Reference numeral 7 denotes an aperture unit which is held in the second lens barrel 4 described above.

Reference numeral 8 denotes a fixed cylinder to which a mount to be described later is integrally attached and which holds the above-described guide cylinder 5 and a unit support cylinder 11 for a focus drive unit to be described later.

Reference numeral 9 denotes a focus operation ring, which is rotatably held by being sandwiched between the above-mentioned guide tube 5 and the above-mentioned fixed tube 8, and which is connected to a manual connection plate 25 of a focus drive unit to be described later via a connection claw 9a. Transmit rotation to

Reference numeral 10 denotes a mount that is attached to the fixed cylinder 8 and mechanically coupled to a camera body (not shown).

Reference numerals 11 to 27 denote components constituting the focus drive unit. Reference numeral 11 denotes a unit support tube for holding each component of the focus drive unit, which is held by the fixed tube 8 described above.

Reference numeral 12 denotes an annular vibration member having a trapezoidal cross section (hereinafter referred to as a stator).

Reference numeral 13 denotes an electrostrictive element which is joined to one end face of the stator 12 and vibrates.
Is a ring-shaped vibration absorber made of felt or the like pressed against the surface.

Reference numeral 15 denotes a first disc spring as a pressurizing means for urging the vibration absorber 14 in the optical axis direction, and 16 denotes a screw thread formed on the outer diameter of the unit support cylinder 11. The first nut for adjusting the pressing force of the first disc spring 15 is adjusted to an optimum pressing force so as to maximize the performance of the vibration wave motor.

Reference numeral 17 denotes a detent for integrally holding the outer diameter of the unit body and for restricting the rotation of the stator 12.

Reference numeral 18 denotes a rotating body which receives a rotational force about the optical axis by the stator 12 (hereinafter, this is referred to as a rotor).
It is.

Reference numeral 20 denotes a rotor 18 via a rubber ring 19
A first connecting plate that rotates integrally with the first connecting plate 20; a friction plate 21 integrally attached to the first connecting plate 20;
The second connecting plate, to which the rotation of the rotor 18 is transmitted via 1, comes into contact with a roller 24 described later.

Reference numeral 23 denotes an output ring which has a plurality of shafts 23a rotatably supporting a later-described planetary roller 24 projecting radially from the optical axis, and transmitting rotation to the cam ring 6 via a focus key 27. .

The second connecting plate 2 is rotatably supported by a plurality of shafts 23a arranged around the output ring 23.
This is a so-called planetary roller that is revolved around the optical axis while being rolled between two manual connection plates 25 described later.

The planetary roller 24 has a tapered peripheral groove having an outer diameter φ2 formed at the center of a roller body having an outer diameter φ1.
5 is the first contact portion (outer diameter φ
1) 24a and a second contact portion (outer diameter φ2) 24b with which the second connecting plate 22 comes into contact with the peripheral groove, and φ1> φ
It is 2.

The planetary roller 24 has two outer diameters and is substantially symmetrical in the vertical direction, so that the roller falls due to the force applied by the contact of the second connecting plate 22 and the manual connecting plate 25. Has been prevented.

Reference numeral 25 denotes a manual connection plate to which rotation is transmitted from the focus operation ring 9. Reference numeral 26 denotes a holding ring for rotatably holding the manual connection plate 25, which is integrally held by the unit support cylinder 11.

Reference numeral 27 denotes a focus key for transmitting the rotation of the output ring 23 to the cam ring 6.

The coefficient of friction between the friction plate 21 and the second connecting plate 22 includes the coefficient of friction between the stator 12 and the rotor 18, the coefficient of friction between the second connecting plate 22 and the planetary roller 24, The coefficient of friction is set so as to be small with respect to any of the friction coefficients between the manual connection plate 24 and the manual connection plate 25.

Next, the operation of the lens barrel in which the focus drive unit according to the present embodiment is disposed will be described.

When the user of the lens barrel operates a focusing switch (not shown) in the autofocus mode, a voltage is applied to the electrostrictive element 13 via a printed circuit board (not shown) by the operation of a control circuit (not shown). As a result, a vibration that proceeds in the circumferential direction is generated in the stator 12, and the vibration of the stator 12 causes the rotor 18, the rubber ring 19, and the first and second connecting plates 20, 22 to rotate about the optical axis.

At this time, since the manual connection plate 25 does not rotate, the roller 24 rolls along the end face of the manual connection plate 25 while rotating around the shaft 23a on the output ring 23. At this time, the output ring 23 is
4 ratio of the outer diameter of the first contact portion to the outer diameter of the second contact portion φ1: φ
When 2 is set to 2: 1, 2/3 of the rotation of the rotor 18 is set.
, And rotate about the optical axis.

Thus, the cam ring 6 is driven via the projection 6b, and accordingly the first lens barrel 3 is driven in the optical axis direction to perform auto-focusing.

On the other hand, when the lens barrel user performs manual focusing, if the focus operating ring 9 is rotated without operating the focusing switch (not shown), the rotation is transmitted to the manual connecting plate 25.

At this time, since the vibration wave motor section is not driven, the rotor 18 is stationary and the planetary roller 2 is not driven.
Only 4 rotates along the end face of the second connecting plate 22 while rotating about the shaft 23 a of the output ring 23.

At this time, the output ring 23 has a ratio φ 1 of the outer diameter of the first contact portion and the second contact portion of the planetary planetary roller 24.
When φ2 is set to 2: 1, the rotation is reduced to ３ with respect to the manual connection plate 25, and the rotation is performed around the optical axis.

As a result, the cam ring 6 is driven via the projection 6b, and accordingly the first lens barrel 3 is driven in the direction of the optical axis to perform manual focusing.

Further, when the rotation of the output ring 23 is restricted and the focus operation ring 9 is further rotated,
The planetary roller 24 does not roll but rotates only around the shaft 23a, and transmits the rotation to the second connecting plate 22 to rotate the second connecting plate 22, but the second connecting plate 22 rotates due to the friction coefficient described above. Since slippage occurs between the two connecting plates 22 and the friction plate 21, rotation is not transmitted to the first connecting plate 20 and the rotor 18.

In the present embodiment, the shape of the planetary roller 24 is determined by changing the outer diameter of the first contact portion 24a with which the manual connecting plate 25 abuts to the second connecting plate 22 with which the second connecting plate 22 abuts. Although the diameter is larger than the outer diameter of the contact portion 24b, the ratio of the diameters may be arbitrary. For example, if the diameters of the first and second contact portions are the same, the holding ring 26
Is 1/2 of the rotation from the vibration wave motor side.
And the rotation from the manual connection plate 25 is reduced to half the rotation.

[0061]

According to the first to fourth aspects of the present invention, when the rotation of the output member is restricted,
Even when the manual drive unit is driven, its rotational force is absorbed by the sliding of the friction clutch means between the driven member and the motor drive unit, so that the friction between the manual drive unit and the driven member, and the friction between the driven member and the driven member. Between clutch means, or
Since no slippage occurs between the motor drive unit and the friction clutch means, there is no effect on the motor drive unit side.

Further, according to the invention according to claims 5 to 8, in a lens barrel capable of automatically switching between an auto focus operation and a manual focus operation as an automatic operation and a manual operation, for example,
Even when the manual drive unit is driven when the rotation of the output member is restricted, the rotational force is absorbed by the slipping of the friction clutch means between the driven member and the motor drive unit, so that the manual drive unit is driven. To provide a lens barrel that does not affect the motor drive unit because no slippage occurs between the motor drive unit and the friction clutch unit, or between the driven member and the friction clutch unit, or between the motor drive unit and the friction clutch unit. Can be.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a lens barrel using a focus drive unit according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a focus unit in a conventional example.

[Explanation of symbols]

 1: Focus lens group 2: Fixed lens group 3: First group lens barrel 4: Second group lens barrel 5: Guide cylinder 6: Cam ring 7: Aperture unit 8: Fixed cylinder 9: Focus operation ring 10: Mount 11: Unit support cylinder 12: Stator 13: Electrostrictive element 14: Vibration absorber 15: First disc spring 16: First nut 17: Detent 18: Rotor 19: Rubber ring 20: First connecting plate 21: Friction Plate 22: Second connecting plate 23: Output ring 24: Planetary roller 25: Manual connecting plate 26: Holding ring 27: Focus key

Claims (8)

[Claims] A driving force from a manual driving unit is input to a first input member, a driving force from a motor driving unit is input to a second input member, and the first input member and the second input member are connected to each other.
In the drive transmission device having a differential transmission means for driving an output member by a differential operation with respect to the input member, a predetermined drive force or more is transmitted to the motor from the first input member side to the motor drive section. A drive transmission device provided with friction clutch means for interrupting the rotation. 2. The friction clutch means includes: a first connecting member frictionally connected to a motor driving unit; a second connecting member frictionally connected to the driven member; and a first connecting member and a second connecting member. 2. The drive transmission device according to claim 1, wherein the drive transmission device is constituted by a friction plate sandwiched between the drive transmission device and the friction transmission member. 3. The motor according to claim 1, wherein the motor is a vibration wave motor for bringing a rotating body and a vibrating body into pressure contact with each other, and the friction clutch means disposed between the rotating body of the vibration wave motor and the second input member. The drive transmission device according to claim 1, further comprising: 4. The differential transmission means is constituted by a differential mechanism in which a planetary roller is rotatably supported by an output member, and rolls while being sandwiched between a first input member and a second input member. The drive transmission device according to claim 1, wherein: 5. A manual driving unit for inputting a driving force to a first input member by manual operation and driving a lens by differential transmission means, and a motor driving force for inputting a motor driving force to a second input member. A lens drive unit having a motor drive unit for driving a lens by a transmission unit, wherein the motor drive unit is provided with friction clutch means for blocking transmission of a predetermined or more drive force from the first input member side to the motor. A lens barrel comprising: 6. The friction clutch means includes: a first connection member frictionally connected to a motor drive unit; a second connection member frictionally connected to the driven member; and a first connection member between the first connection member and the second connection member. 6. A lens barrel according to claim 5, wherein said lens barrel comprises a friction plate sandwiched between said lens barrel and said lens barrel. 7. The vibration wave motor for bringing a rotating body and a vibrating body into pressure contact with each other, wherein the friction clutch means is arranged between the rotating body of the vibration wave motor and the second input member. The lens barrel according to claim 5, further comprising: 8. The differential transmission means includes a differential mechanism in which a planetary roller is rotatably supported by an output member and rolls while being sandwiched between a first input member and a second input member. The lens barrel according to claim 5, wherein: