JPH087313B2 - Lens barrel drive for camera with variable focus device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a camera provided with a variable focus device in which the focal length of a taking lens is switched by moving a lens barrel holding the taking lens forward and backward with respect to a camera body. The present invention relates to a drive device for moving the lens barrel of the doll back and forth.

[Prior Art] A bifocal camera whose focal length can be switched between a standard shooting position and a telephoto shooting position so that photography can be performed easily.
Alternatively, a camera with a variable focus device, such as a camera with a zoom lens, whose focal length can be continuously changed, is widely used.

In this variable focus device, the focal length is changed by moving the lens barrel holding the photographing lens forward and backward with respect to the camera body in the optical axis direction by using the power of a motor or the like.

Conventionally, in this type of camera, when the lens barrel stops, the lens barrel is fixed to the camera body at that position. In particular, in a bifocal camera, focusing is performed at the standard position and the telephoto position, so it is inconvenient if the lens barrel is located at any other position, and the lens barrel is locked at that position. Even in a camera with a zoom lens, if the protruding lens barrel is inadvertently pushed back, the components that drive it will be damaged and the lens barrel will be locked.

[Problems to be solved by the invention]

However, when the lens barrel is protruding, the lens barrel may be damaged or deformed when the camera is inadvertently dropped or hit and external force is applied to the lens barrel. Therefore, the deformed portion or the damaged portion becomes an obstacle, and the lens barrel cannot be retracted, and thereafter, it becomes impossible to shoot at the position where the lens barrel is retracted.

Further, when a force for pulling out the lens barrel is applied from the outside, the lock mechanism may be damaged.

Therefore, the present invention allows the lens barrel to freely move when a force is applied to the lens barrel from the outside, and also allows the lens barrel to be freely moved even when the force from the outside is small. Since it is inconvenient if it moves, it is an object of the present invention to provide a lens barrel driving device that can appropriately resist external force.

[Means for solving problems]

In order to achieve the above object, a lens barrel driving device according to the present invention is a mirror of a camera equipped with a variable focus device for changing a focal length of a photographing lens by moving a lens barrel forward and backward with respect to a camera body by rotation of a motor. In the barrel driving device, a pair of power transmission elements having the same rotation axis are provided in a power transmission path from the motor to the lens barrel, and the pair of power transmission elements are rotatable with respect to each other. A mountain portion having inclined surfaces inclined in the respective rotation directions of the surfaces facing each other in the rotation axis direction is formed, and one of the pair of power transmission elements is slidable in the axial direction. Of the power transmission element is slidable by sliding the power transmission element, and the power transmission element is biased in a direction in which the power transmission elements engage with each other. Working in between By frictional forces thus performs transmission power between these power transmission elements, one of the transfer element of the power transmission path from the motor to the power transmission element,
Power is transmitted from the motor to the power transmission element, and is a one-way transmission element that is a large load for transmission of power from the power transmission element to the motor.

[Work]

Since the power transmission between the pair of power transmission elements is performed by frictional force and these are made rotatable relative to each other, when the load applied to any of the power transmission elements is larger than this frictional force, When the power transmission element rotates, the other does not rotate. Therefore, for example, when an external force is applied in a direction that prevents the lens barrel from advancing while the motor is operating, the power transmission element on the motor side is rotated by the power of the motor, but the power transmission element on the lens barrel side is rotated. Does not rotate. In addition, a power transmission element that transmits power from the motor to one of the pair of power transmission elements transmits power from the motor, but a large load is transmitted when power is transmitted from the one power transmission element to the motor. Therefore, when an external force for moving the lens barrel is applied while the motor is stopped, the power transmission element on the lens barrel side rotates but the one on the motor side does not rotate. That is, the lens barrel moves back and forth with respect to the camera body by an external force.

Moreover, since the mountain portions are formed on the surfaces of the pair of power transmission elements that face each other, the frictional force between these power transmission elements is increased and the power can be reliably transmitted, and when a load is applied, When one of the power transmission elements rotates, one of the power transmission elements slides along the shaft and the engagement of the inclined surface is released. Therefore, one power transmission element rotates but the other does not. That is, the lens barrel moves back and forth with respect to the camera body by an external force.

〔Example〕

Hereinafter, a lens barrel driving device for a camera with a variable focus device according to the present invention will be specifically described based on the illustrated embodiments.

First, the structure of the lens driving unit of a compact camera equipped with a zoom lens in which the lens group is moved by the lens barrel driving device will be described with reference to FIG.

This zoom lens is a two-group zoom including a front group lens 1 and a rear group lens 2. The front lens group 1 is housed in a shutter unit 3 and fixed to the front part of a movable lens barrel 4 of the shutter unit 3 by three setscrews 3a. In addition,
Of the setscrews 3a, two setscrews 3a have spring washers.
The inclination of the front lens group 1 in the optical axis direction can be adjusted by interposing 3b.

The movable lens barrel 4 has a shape in which a mounting plate 4a for fixing the shutter unit 3 is formed on a substantially rectangular frame member. A guide hole 4b is formed in the rear of the upper surface of the movable lens barrel 4 in a substantially rectangular shape in parallel with the optical axis to provide a guide hole 4b.
Then, the rear group lens 2 is arranged at the rear portion of the movable lens barrel 4 by inserting the protrusion 5a formed on the upper end portion of the lens mount 5 of the rear group lens 2.

A guide portion 5b is provided by forming a through hole in a direction parallel to the optical axis at the lower side end portion of the lens mount 5, and a bush 5c is fitted to the guide portion 5b. The rear group guide rod 6a is inserted through the bush 5c, and the tip of the rear group guide rod 6a on the side of the movable lens barrel 4 is supported by a support portion provided in the movable lens barrel 4. A pressing plate 6b is brought into contact with the rear end of the rear group guide rod 6a, and the pressing plate 6b is fixed to the movable lens barrel 4 by a set screw 6c. A pushing spring 6d is wound between the lens mount 5 of the rear group guide rod 6a and the above-mentioned supporting portion in the movable lens barrel 4, and the restoring force of the pushing spring 6d is adjusted by the lens mount 5 to the guide hole 4b and the rear group. It is urged to move backward by being guided by the guide rod 6a.

Form an appropriate depression on the lower surface of the lens mount 5,
The eccentric pin 7a of the focus adjustment pin 7 and the flange are in this recess.
7b and the pressing plate 7c is fixed to the lens mount 5 with a set screw 7d to fix the focus adjustment pin 7 to the lens mount 5. A circular fulcrum pin 7e is formed on the focus adjusting pin 7 fixed to the lens mount 5, and the fulcrum pin 7e is passed through the through hole portion 7f of the pressing plate 7c to form the interlocking hole 8a of the interlocking lever 8. Insert loosely.

The interlocking lever 8 is substantially L-shaped, and the interlocking hole 8a is formed at the tip of one arm portion thereof. A through hole 8b is formed in the substantially L-shaped bent portion, and a supporting screw 8c penetrating the through hole 8b.
Is fastened to the lower surface of the movable lens barrel 4, and the interlocking lever 8 is provided on the movable lens barrel 4 so as to be rotatable around the support screw 8c. In addition, at the tip of the other arm of the interlocking lever 8,
Interlocking pin projecting in the direction opposite to the movable lens barrel 4
8d is provided.

A through hole is formed in the rear side surface of the movable lens barrel 4 to form a cam portion 9
Is provided.

Further, a main guide portion 4c having a through hole formed in the optical axis direction is provided at a side end portion of the upper surface of the movable lens barrel 4, and a bush 4d is fitted into the main guide portion 4c. A cam plate 10 having a cam surface 10a is fixed near the side of the main guide portion 4c. In addition,
The cam plate 10 may be common to the main guide portion 4c, and the cam surface 10a may be formed on the side surface of the main guide portion 4c. As shown by a broken line, a sub-guide portion 4e having a U-shaped tip is cut out at the lower part of the side surface of the movable lens barrel 4 opposite to the side surface on which the cam portion 9 is provided.

As described above, the movable lens barrel 4 on which the front lens group 1, the rear lens group 2, the interlocking lever 8 and the like are mounted is housed in the fixed frame 11 fixed to the camera body A (shown in FIG. 5). At this time,
The main guide rod 4f is inserted into the main guide portion 4c, and the rear end portion of the main guide rod 4f is supported by the support portion 11a above the rear end portion of the fixed frame 11. Further, the auxiliary guide bar 4g is inserted into the notch at the tip of the auxiliary guide portion 4e, and the rear end portion is supported by the support portion 11b provided on the inner side surface of the fixed frame 11. Then, the frame-shaped lid body 12 is fastened and fixed to the front peripheral edge of the fixed frame 11 with the set screw 12a.

As shown in FIGS. 4 and 5, the lower surface of the fixed frame 11 is provided with a cam hole 13 in which a cam surface 13a is formed, and the side surface of the interlocking pin 8d of the interlocking lever 8 contacts the cam surface 13a. .

Further, a worm 14 having a rotation axis in the vertical direction is arranged on the side surface of the fixed frame 11, and the rotation axis of the worm 14 is projected above the upper surface of the fixed frame 11, and the drive gear is attached to this projection. There are fifteen. On the upper surface of the fixed frame 11, a gear train 16 having an appropriate reduction ratio, which is composed of an appropriate number of gears such as a gear 16a, is arranged, and the rotation of a motor (not shown) is transmitted to the drive gear 15 via this gear train 16. . A worm wheel 17 pivotally supported on the side surface of the fixed frame 11 meshes with the worm 14, and a combination of the worm 14 and the worm wheel 17 constitutes a one-way transmission element. This worm wheel
A transmission gear 18 is provided coaxially with 17. The worm wheel 17 and the transmission gear 18 are rotatable relative to each other, and by applying an appropriate frictional force between these side surfaces, when the load applied to these gears exceeds a predetermined magnitude,
One gear is stopped and the other gear is idle. The power transmission system will be described later in detail.

An intermediate gear 19 pivotally supported on the fixed frame 11 meshes with the transmission gear 18, and a gear for driving the encoder 20 to the intermediate gear 19.
20a and fan-shaped gear 21 mesh with each other.

The rotation shaft 21a of the fan-shaped gear 21 penetrates a through hole 11c formed in the side surface of the fixed frame 11, and the tip end of the rotation shaft 21a has a notch 4h formed at the rear lower end of the movable lens barrel 4. It is located inside the movable lens barrel 4 which has passed through and is accommodated in the fixed frame 11. The base end of the input lever 22 is fixed to the tip of the rotary shaft 21a with a set screw 22a so that the input lever 22 and the sector gear 21 rotate in synchronization. A drive pin 22b is provided on the free end of the input lever 22 so as to be oriented in the direction of the sector gear 21, and the drive pin 22b is attached to the movable lens barrel 4.
It is loosely inserted in the cam portion 9 formed on the side surface of the.

The movable lens barrel 4 which is the upper surface of the fixed frame 11 and is accommodated in the fixed frame 11.
The portion of the cam plate 10 located substantially above the cam plate 10 has a cam surface
A through hole 11d having a shape corresponding to 10a is formed. An interlocking plate 23 is rotatably supported on the upper surface of the fixed frame 11 by a set screw 23a so that the interlocking plate 23 can rotate about the center thereof. This interlocking board 23
An engaging pin 23b directed downward is projected from one end of the cam plate 10 through the through hole 11d.
Is in contact with the cam surface 10a. An input pin 23c directed upward is provided at the other end of the interlocking plate 23 so as to project upward, and the input pin 23c is interlocked with a variable magnification mechanism (not shown) of the finder. The interlocking plate 23 may be pivotally supported on the camera body A or the case of the finder.

Next, a power transmission system from the worm 14 to the transmission gear 18 will be described with reference to FIGS.

FIG. 2 is a front sectional view with a part cut away, and as shown in the figure, the transmission gear 18 is formed integrally with a boss portion 18a extending long to the right. A bearing 36 is provided at the end of the boss portion 18a, and the bearing 36 is attached to a bracket 37 fixed to the fixed frame 11. Further, a journal portion 18b is formed on the opposite side of the transmission gear 18 from the boss portion 18a, and the journal portion 18b is loosely inserted in a bearing portion provided in the fixed frame 11, and the transmission gear 18 is fixed to the fixed frame 11. To be freely rotatable.

The worm wheel 17 is loosely fitted to the boss portion 18a of the transmission gear 18 so that the worm wheel 17 and the transmission gear 18 can rotate relative to each other, and the worm wheel 17 slides axially with respect to the transmission gear 18. Be free to move. The end surface of the boss portion 17a of the worm wheel 17 faces the bearing 36, and the push spring 38 is wound around the boss portion 17a. The restoring force of the push spring 38 causes the worm wheel 17 to continuously transmit the gear.
Side of worm wheel 17 and bearing 36 so that it presses against 18
It is urged between and.

On the respective surfaces of the worm wheel 17 and the transmission gear 18 which are opposed to each other, a mountain portion 39 is radially formed, and both sides of this mountain portion 39 are inclined surfaces 39a and 39b. The gentle slope 39a is a gentle slope, and the slope 39b is a steep slope. Face each other.

Further, the worm 14 and the worm wheel 17 are configured such that the rotation of the motor (not shown) is transmitted from the worm 14 to the worm wheel 17 and the worm wheel 17 is rotated by appropriately adjusting the number of threads and the lead angle. The worm wheel 14 acts as a load to prevent the worm wheel 17 from rotating when trying to rotate.

The operation of the lens barrel driving device according to the present invention configured as described above will be described together with the movement operation of the front lens group 1 and the rear lens group 2.

When a motor (not shown) rotates, the drive gear 15 rotates via the gear train 16 and the worm 14 rotates. Warm 14
When the worm rotates, the worm wheel 17 meshed with the worm rotates, and the frictional force between the worm wheel 17 and the worm wheel 17 causes the transmission gear 18 to rotate. The rotation of the transmission gear 18 is the rotation of the intermediate gear 19
Is transmitted to the fan-shaped gear 21 via the rotary shaft 21a, and the fan-shaped gear 21 rotates about the rotation shaft 21a in the arrow P direction in FIG. In addition,
The rotation of the motor when the fan gear 21 is rotated in this direction is defined as forward rotation.

When the fan-shaped gear 21 rotates, the input lever 22 that is coaxial with the fan-shaped gear 21 synchronously swings in the same direction. Therefore, the drive pin 22b of the input lever 22 turns in the same direction as the fan gear 21 about the turning shaft 21a. The cam portion 9 is pushed by the turning of the drive pin 22b, and the drive pin 22b moves from the upper end portion to the lower end portion of the cam portion 9. Therefore, the movable lens barrel 4 forming the cam portion 9 is guided by the main guide portion 4c and the sub guide rod 4g and moves forward with respect to the fixed frame 11, that is, toward the subject side. A shutter unit 3 including the front lens group 1 is fixed to the front part of the movable lens barrel 4, and the front lens group 1 also moves forward.

When the movable mirror movement 4 advances, the interlocking lever 8 pivotally supported by the movable mirror movement 4 also moves. Since the interlocking pin 8d of the interlocking lever 8 is in contact with the cam surface 13a of the cam hole 13a formed in the fixed frame 11, when the interlocking lever 8 moves forward with respect to the fixed frame 11, the interlocking lever 8 moves to the cam surface 13a. It is guided to rotate counterclockwise in FIG. 5 about the support screw 8c. On the other hand, since the lens mount 5 of the rear group lens 2 is connected to the interlocking lever 8 via the focus adjustment pin 7,
The rotation of the interlocking lever 8 moves the lens mount 5 forward with respect to the movable lens barrel 4 against the restoring force of the push spring 6d. Therefore, the rear lens group 2 moves forward with respect to the movable lens barrel 4, and the distance between the rear lens group 2 and the front lens group 1 is narrowed.
The focal length is continuously changed. When the movable lens barrel 4 moves to the forefront, the front lens group 1 and the rear lens group 2 are located at the forefront, and the rear lens group 2 is used for the front lens group 1.
And the focal length becomes the longest. Also drive pin
22b is located at the lower end of the cam portion 9, and the tip of the movable lens barrel 4 is located at a position protruding from the fixed frame 11. The front lens group 1
In order to secure an optical positional relationship when the rear lens group 2 and the rear lens group 2 perform zooming, the cam curve of the cam surface 13a may be designed to be a predetermined one.

In order to retract the movable lens barrel 4 from the state in which the drive pin 22b is located at the T end 9c of the cam portion 9 and the movable lens barrel 4 is located at the forefront, a motor (not shown) is reversely rotated. Good. Since the fan gear 21 rotates in the direction of the arrow P in FIG. 4 by the reverse rotation of the motor, the drive pin 22b also rotates in the same direction. Therefore, contrary to the above, the movable lens barrel 4 retracts while being accommodated in the fixed frame 11.

The lens mount 5 is a push spring so that it always moves backward.
Since the interlocking lever 8 receives the restoring force of 6d and the clockwise rotation in FIG. 5 via the focus adjusting pin 7, the interlocking pin 8d receives the force of the cam surface 13a.
Is in contact with Therefore, the interlocking pin 8d becomes the cam surface 13a.
And is rotated clockwise around the support screw 8c in FIG. Therefore, the fulcrum pin 7e also turns in the same direction, and the lens mount 5 retracts with respect to the movable lens barrel 4.
As a result, the rear lens group 2 retreats, and in cooperation with the retreat of the front lens group 1 accompanying the movable lens barrel 4, the focal length is continuously changed to the shortest distance.

Then, with the movable lens barrel 4 protruding from the fixed frame 11,
When an external force is applied to the lens barrel carelessly by dropping or hitting the camera, this moving force causes the movable lens barrel 4 to retreat and the sector gear 21 to rotate in the direction of the arrow P in FIG. Move. This rotation of the sector gear 21 rotates the intermediate gear 19, and this rotation is transmitted to the transmission gear 18. On the other hand, the worm wheel 17, which is engaged with the transmission gear 18 by the inclined surfaces 39a and 39b, is meshed with the worm 14, which is a load, so the worm wheel 17 does not rotate. Therefore, the force applied to the worm wheel 17 by the rotation of the transmission gear 18 resists the restoring force of the push spring 38 and thus the worm wheel 17.
17 slides to the right in FIG. By this sliding, the engagement between the worm wheel 17 and the inclined surfaces 39a, 39b of the transmission gear 18 is released. Further, when the crest 39 of the worm wheel 17 gets over the crest 39 of the transmission gear 18, the restoring force of the push spring 38 causes the worm wheel 17 to slide to the left, and as shown in FIG. 39a and 39b are engaged. in this way,
The inclined surfaces 39a, 39b are repeatedly engaged and disengaged, and the transmission gear 18 idles with respect to the worm wheel 17. Therefore, the retraction of the movable lens barrel 4 is allowed by the external force. When the worm wheel 17 slides, since the tooth traces of the worm 14 and the worm wheel 17 are twisted, they are guided by the tooth traces and rotate slightly.

Further, even when the moving lens barrel 4 which is retracting is inadvertently pulled out, the rotation of the sector gear 21 due to the forward movement of the moving lens barrel 4 is transmitted to the transmission gear 18 and rotates, but the worm wheel 17 Since it does not rotate, the transmission gear 18 idles and the forward movement of the movable lens barrel 4 is allowed.

When the movable lens barrel 4 is advanced or retracted by the rotation of a motor (not shown), the movable lens barrel 4 is stopped when the movable lens barrel 4 is positioned at the forward end or the backward end, or when the forward or backward movement of the movable lens barrel 4 is obstructed. Therefore, when the transmission gear 18 does not rotate, the worm wheel 17 idles with respect to the stopped transmission gear 18 even if the motor continues to rotate, and does not damage other power transmission elements or the like.

In this embodiment, the side surface of the mountain portion 39, the gentle slope 39a, and the steep slope 39b are formed, but the slopes 39a and 39b having the same angle may be used. However, generally, the magnitude of the transmission torque of the motor is different from that of the transmission torque generated by the external force, so that the friction angle between the worm wheel 17 and the transmission gear 18 varies depending on the rotation direction by varying the inclination angle. The maximum transmission torque can be changed depending on the rotation direction. For example, it is preferable that the transmission gear 18 idles easily with respect to an external force in the direction in which the movable lens barrel 4 is retracted. Therefore, in the rotation direction of the transmission gear 18 caused by the external force in this direction, the gentle slopes 39a contact each other. To do so. The magnitude of the frictional force between the worm wheel 17 and the transmission gear 18 can also be changed by changing the number of the crests 39, changing the length of the crests 39 in the radial direction, or changing the elastic modulus of the push spring 38. Can be adjusted.

〔The invention's effect〕

As described above, according to the lens barrel driving device for a camera with a variable focus device according to the present invention, a pair of power transmission elements for transmitting power by frictional force are provided in the power transmission path from the motor to the lens barrel. When the load such as an external force is larger than the frictional force, one power transmission element idles with respect to the other power transmission element, so that the lens barrel is allowed to move due to an external force, The parts will not be deformed or damaged. Therefore, the durability of the lens barrel and parts can be improved.

Moreover, since the mountain portion is formed on the surface on which the frictional force between the pair of power transmission elements acts, the inclination angle of the inclined surface may be different with respect to the rotation direction, or the number and length of the mountain portions may be changed. As a result, the frictional force can be changed according to the rotation direction. Therefore, it is possible to easily cope with the transmission torque according to the rotation of the motor and the external force.

[Brief description of drawings]

FIG. 1 is a side view showing a main part of a lens barrel driving device according to the present invention. FIG. 2 is a front sectional view in which a part is similarly cut. FIG. 3 is a partially omitted perspective view showing a facing surface of one of the pair of power transmission elements. Fourth
FIG. 1 is an exploded perspective view showing an example of a zoom lens equipped with a lens barrel driving device according to the present invention. FIG. 5 is a partial cross-sectional view taken along the horizontal line of the state where the movable lens barrel is housed in the fixed frame. 1 ... Front group lens, 2 ... Rear group lens 4 ... Moving lens barrel, 5 ... Lens mount 11 ... Fixed frame, 14 ... Worm 17 ... Worm wheel (power transmission element) 17a ... Boss part 18 …… Transmission gear (power transmission element) 18a …… Boss portion, 19 …… Intermediate gear 21 …… Fan-shaped gear, 22 …… Input lever 36 …… Bearing, 37 …… Bracket 38 …… Press spring, 39 …… Mountain part 39a ... gentle slope, 39b ... steep slope A ... camera body

Front page continuation (72) Inventor Masashi Takamura 2-26-30 Nishiazabu, Minato-ku, Tokyo Fuji Shashin Film Co., Ltd. (56) Reference JP-A-60-163010 (JP, A) 70818 (JP, U) Showa 45-13923 (JP, Y1)

Claims (1)

[Claims] 1. A lens barrel driving device for a camera, comprising a variable focus device for moving a lens barrel forward and backward with respect to a camera body by rotating a motor to change a focal length of a photographing lens, wherein the motor extends from the motor barrel to the lens barrel. A pair of power transmission elements having the same rotation axis are provided in the power transmission path, and the pair of power transmission elements are rotatable with respect to each other. Forming a mountain portion having an inclined surface inclined in the rotation direction, allowing one of the pair of power transmission elements to slide in the axial direction, and the inclined surface formed in the pair of power transmission elements is The transmission element is slidable by sliding and is biased to the power transmission element in a direction in which the inclined surfaces are engaged with each other. The power is transmitted from the motor to the power transmission element through any of the transmission elements in the power transmission path from the motor to the power transmission element, and the power is transmitted from the power transmission element to the motor. A lens barrel driving device for a camera with a variable focus device, characterized in that it is a one-way transmission element that is a heavy load.