JP2003120760A - Driving force transmission device, and camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a driving force transmission device capable of absorbing impact from the external without increasing cost or size. SOLUTION: This driving force transmission device transmits power of a driving source to a driven member through a gear train. At least one gear 4e of the gear train is formed of an elastic member, so that it is elastically deformed when rotation force of a prescribed rotation torque or more is added.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an impact absorption type driving force transmission device capable of absorbing an impact caused by an external force, for example, a driving force transmission device used in a camera or the like.

[0002]

2. Description of the Related Art A shock absorbing drive force transmission mechanism will be described with reference to FIGS.

FIG. 8 is a component exploded perspective view showing the structure of a clutch mechanism incorporated in a driving force transmission mechanism of the first conventional technique. FIG. 9 is a component exploded perspective view showing the configuration of the clutch mechanism incorporated in the driving force transmission mechanism of the second conventional technique. FIG. 10 is a component exploded perspective view showing the configuration of the clutch mechanism incorporated in the driving force transmission mechanism of the third conventional technique. FIG. 11 is a perspective view showing a drive unit in which a drive force transmission mechanism is incorporated.

In the clutch mechanism (FIG. 8) of the first prior art, the first drive gear 100 and the second drive gear 10 are used.
The leaf spring 102 is disposed between the leaf spring 10 and the first drive gear 100, and the leaf spring 10 is provided in a hole (not shown) provided in the end surface of the first drive gear 100.
By engaging the two protrusions 102a, the first drive gear 1
00 and the leaf spring 102 rotate together.

The leaf spring 102 is the leaf spring 10.
When the second driving gear 101 has a diameter larger than the inner diameter of the second natural state (before the assembling), it is charged in the radial direction by being incorporated into the shaft 101a. Due to the spring pressure of the leaf spring 102, a frictional force is applied between the shaft 101a of the second drive gear 101 and the leaf spring 102, and the frictional force causes the first drive gear 100 and the second drive gear 101 to be integrated. It is designed to rotate with.

That is, in the clutch mechanism according to the above-mentioned first prior art, the shaft 101 of the second drive gear 101 is used.
The torque is transmitted only by the frictional force between a and the leaf spring 102, and the shaft 101
The friction surface between a and the leaf spring 102 slides to absorb the impact.

In the second conventional clutch mechanism (FIG. 9), the first drive gear 110 and the second drive gear 11 are used.
1, the leaf spring 112 is disposed between the first drive gear 110 and the leaf spring 112, and the end 112a of the leaf spring 112 engages with the convex portion 110a formed on the first drive gear 110. 112 is designed to rotate integrally.

The leaf spring 112 is the leaf spring 11
By being mounted on the inner wall (not shown) of the second drive gear 111 having a smaller diameter than the outer shape of the second natural state (before mounting), it is charged in the radial direction. This leaf spring 11
A spring force of 2 gives a frictional force between the inner wall of the second drive gear 111 and the leaf spring 112, and the friction force causes the first drive gear 110 and the second drive gear 111 to rotate integrally. It has become.

That is, in the above-mentioned second conventional clutch mechanism, torque is transmitted only by the frictional force between the inner wall of the second drive gear 111 and the leaf spring 112, and when an impact is applied from the outside. Inner wall and leaf spring 11
The friction surface with 2 slips and absorbs the impact.

In the clutch mechanism (FIG. 10) according to the third prior art, one end face of the first drive gear 120 and the second drive gear 121 in the rotational axis direction is provided with a protrusion extending in the rotational axis direction. Portions 120a and 121a are formed. The first drive gear 120 and the second drive gear 121 are rotatably fitted to the shaft 123 in a state where the convex portion 120a and the convex portion 121a face each other. Here, the coil spring 122 is incorporated between the other end surface of the second drive gear 121 and the flange portion 123 a of the shaft 123. Then, a nut 125 is tightened via a washer 124 at the tip of the shaft 123 protruding from the hole of the first drive gear 120. As a result, the first drive gear 120 and the second drive gear 121 are held.

In the above-mentioned structure, the coil spring 122 constantly biases the second drive gear 121 in the direction of arrow D1. Therefore, one end surface of the first drive gear 120 and the second drive gear 121 are A frictional force is applied to the end face. This friction force and the convex portion 120 of the first drive gear 120
a and the engagement of the convex portion 121a of the second drive gear 121, the first drive gear 120 and the second drive gear 1
21 is integrally rotated to transmit torque. Further, when an external impact is applied to this clutch mechanism, the second drive gear 121 moves in the direction of arrow D2 against the biasing force of the coil spring 122 by this external force, and the second protrusion 120a and the second protrusion 121a move. The disengagement of the mesh absorbs external shock.

Further, Japanese Patent Publication No. 8-7313 and Japanese Patent Publication No. 8-7314 describe a clutch mechanism shown in FIG.

In this clutch mechanism, the convex portion 211b and the convex portion 21 are formed on one of the end faces of the worm wheel 211 and the transmission gear 212 which face each other in the rotation axis direction.
2b is formed. The worm wheel 211 is rotatably fitted to the boss portion 212a of the transmission gear 212, and a bearing 213 is screwed to the tip portion of the boss portion 212a.

The boss portion 211a of the worm wheel 211
A coil spring 214 is arranged on the outer periphery of
This coil spring 214 is a worm wheel 211
Is urged in the direction of arrow D3 and pressed against the transmission gear 212. As a result, a frictional force is applied between one end surface of the worm wheel 211 (the surface on which the convex portion 211b is formed) and one end surface of the transmission gear 212 (the surface on which the convex portion 212b is formed). By this frictional force and the meshing of the convex portion 211b and the convex portion 212b, the worm wheel 211 and the transmission gear 212 integrally rotate to transmit torque. Further, when an external impact is applied to the clutch mechanism, the worm wheel 211 moves in the direction of arrow D4 against the biasing force of the coil spring 214 due to this external force, and the engagement with the convex portion 211b and the convex portion 212b is disengaged. It is designed to absorb external shocks.

[0015]

However, the above-mentioned shock absorption type driving force transmission mechanism has the following drawbacks.

The above-mentioned first prior art (FIG. 8) and second
In the configuration of the clutch mechanism shown in the related art (FIG. 9),
Since it is a method of transmitting torque by utilizing the frictional force on the circumferential friction surface, it is suitable for absorbing shock from the outside, but when trying to generate high transmission torque,
It is necessary to increase the friction surface by enlarging the inner peripheral area of the leaf springs 102 and 112 or increasing the overall length thereof. As a result, the overall length of the driving force transmission mechanism increases and the external shape increases. I will become.

The transmission torque is adjusted by the leaf spring 102,
The leaf spring 10 having a different charge amount (a different inner diameter) is used because the charge amount of 112 is changed in the radial direction.
It is necessary to prepare several kinds of 2, 112, and it is difficult to reduce the cost and obtain a stable transmission torque.

The clutch mechanism (FIG. 10) in the third prior art, Japanese Patent Publication No. 8-7313 and Japanese Patent Publication No. 8-
The clutch mechanism (FIG. 12) described in Japanese Patent No. 7314 has a large number of parts, so that the cost increases and the driving force transmission mechanism increases in size.

When the transmission torque is adjusted again after the drive force transmission mechanism is incorporated in the drive unit 130 as shown in FIG. 11, the drive force transmission mechanism is used.
Since it needs to be removed from 30, there is a problem in that this adjustment takes time.

Therefore, a first object of the present invention is to transmit a driving force with a small number of parts and to absorb an impact against an external force, thereby reducing the cost and downsizing. To provide.

A second object of the present invention is to provide a driving force transmission device capable of adjusting the transmission torque using only one type of component and reducing the cost. is there.

Further, a third object of the present invention is to provide a driving force transmission device which can easily adjust the transmission torque even after incorporating the driving force transmission device.

[0023]

According to a first aspect of the present invention, in a driving force transmission device for transmitting power of a driving source to a driven member via a gear train, at least one gear in the gear train is elastic. It is formed of a member and is elastically deformed when a rotational force of a predetermined rotational torque or more is applied.

By forming at least one gear of the gear train with an elastic member in this way, the power of the drive source can be transmitted to the driven member, and at the same time a torque greater than a predetermined rotational torque can be applied from the driven member side. When a rotational force is applied, the gear elastically deforms, so that a rotational force equal to or greater than a predetermined rotational torque can be prevented from being transmitted to the gear stage on the drive source side, and an external impact can be absorbed. And
Since at least one gear in the gear train is made of a different material, it is possible to prevent an increase in the number of parts and an increase in cost and an increase in size of the driving force transmission device.

Here, at least one gear can be incorporated as a gear stage on the driven member side of the gear train.

A second invention of the present application is characterized in that the at least one gear has an adjusting means for displacing the at least one gear in a rotation axis direction of the gear to change a meshing tooth width with an adjacent gear.

Thus, the transmission torque can be easily adjusted only by displacing at least one gear in the rotation axis direction of the gear, and a plurality of gear teeth having different thicknesses are used to adjust the transmission torque. Since it is not necessary to prepare different kinds of gears, the cost can be reduced.

Here, the adjusting means includes an urging member for urging at least one gear toward one side in the rotation axis direction of the gear,
At least one gear can be constituted by a holding member that pushes the gear against the urging force of the urging member and holds the state of the gear after the displacement. With such a configuration, the meshing tooth width of the gear can be easily changed only by pushing at least one gear by the holding member without disassembling the driving force transmission device.

The driving force transmission device of the present invention can be incorporated into a camera and used to drive a lens barrel that can be extended and retracted in the optical axis direction.

[0030]

BEST MODE FOR CARRYING OUT THE INVENTION (First Embodiment) A driving force transmission mechanism according to a first embodiment of the present invention will be described with reference to FIGS.

FIG. 1 is an exploded perspective view showing the structure of the driving force transmission mechanism of this embodiment, and FIG. 2 is a perspective view of the driving force transmission mechanism (after assembly). 3 is an exploded perspective view showing a configuration of a lens barrel unit in which a driving force transmission mechanism is incorporated, FIG. 4 is a front view of a camera body in which the lens barrel unit is incorporated, and FIG. 5 is a gear in the driving force transmission mechanism. FIG. 7 is a diagram illustrating the operation of FIG.

1 to 5, 1 is a driving force transmission mechanism, 6 is a lens barrel unit, and 7 is a camera body.
The driving force transmission mechanism 1 is composed of a gear base plate 2, a motor 3, a reduction gear train 4, and a gear retainer plate 5. Of the reduction gear train 4, the motor 3 into which the gear 4a is press-fitted is a screw (not shown).
It is fixed to the gear base plate 2 by.

The gears 4b to 4e of the reduction gear train 4 are rotatably supported by the gear base plate 2, and the gear holding plate 5 is provided.
Is held by. Further, the gear 4f of the reduction gear train 4 is rotatably supported by the fixed barrel 6a of the lens barrel unit 6, and the cam barrel 6b of the lens barrel unit 6 is supported.
Meshes with a gear portion (not shown) formed on the outer periphery of the.

The lens barrel unit 6 of the reduction gear train 4
The gear 4e disposed on the side (post-stage side) is formed of a material that can return to its original shape (elastic deformation) even if the teeth of the gear are deformed. The material of the gear 4e can be appropriately selected according to the characteristics of the driving force transmission mechanism. For example, when a high transmission torque is to be generated, a material suitable for this can be selected. Here, the material of the gear 4e may be, for example, Iron Rubber (trademark) manufactured by NOK. The iron rubber is a kind of polyurethane rubber, which is an elastic material in the intermediate region between rubber and plastic and has flexibility.

The rotational force of the motor 3 is generated by the reduction gear train 4 from the gear 4a to the gear 4b, the gear 4c, the gear 4d, and the gear 4.
e and the gear 4f are transmitted in this order. The rotational force of the motor 3 is reduced by the reduction gear train 4.

As shown in FIG. 3, the driving force transmission mechanism 1 is fixed to the lens barrel unit 6 with screws (not shown),
The gears 4e and 4f of the reduction gear train 4 mesh with each other. The lens barrel unit 6 is fixed to the camera body 7 with screws (not shown) as shown in FIG.

Next, the driving force transmitting operation in the above-mentioned structure will be described.

The rotational force of the motor 3 is transmitted from the gear 4a of the reduction gear train 4 to the cam barrel 6b of the lens barrel unit 6 via the gear 4f. Since the cam barrel 6b is engaged with the fixed barrel 6a in a helicoidal manner, it receives the rotational force of the motor 3 and extends or retracts in the optical axis direction while rotating around the optical axis with respect to the fixed barrel 6a.

When an external force is applied to the front end of the lens barrel unit 6 in a state where the lens barrel unit 6 is extended, the gear 4f is rotated by moving the cam barrel 6b back and forth in the optical axis direction. The rotation of the gear 4f is caused by the rotation of the gear 4e.
However, as described above, the gear 4e is formed of an elastically deformable material. Therefore, when a rotational force of a predetermined torque or more is applied to the gear 4e, the teeth of the gear 4e are By deforming (dotted line portion) as shown in FIG. 5, only the gear 4f rotates without transmitting the rotational force of the gear 4f to the gear 4e.

By thus rotating only the gear 4f, the external impact is not transmitted to the gear arranged on the front side (motor 3 side) of the gear 4d, and the impact from the outside can be absorbed.

On the other hand, when an external impact is applied to the tip of the lens barrel unit 6, if all the gears arranged in the driving force transmission mechanism rotate to the motor shaft of the motor 3, the gears are Although an unreasonable force is not applied, if a gear (worm gear) 4a is used in the driving force transmission mechanism as shown in FIG. 1, rotation can be transmitted from the gear 4a to the gear 4b, but from the gear 4b. Since the rotation to the gear 4a is hard to be transmitted, an unreasonable force is applied to the gear 4a. Further, when many gears are arranged in the driving force transmission mechanism and the torque transmission efficiency is deteriorated, it is possible that one of the plurality of gears arranged in the driving force transmission mechanism cannot rotate. In some cases, a high load may be applied to the gear that cannot rotate.

In the present embodiment, the gear 4e for absorbing an external impact is arranged on the rear stage side of the reduction gear train 4, that is, at a position near the lens barrel unit 6, so that the external impact is quick. Since it can be absorbed in stages, it is possible to prevent a high load from being applied to the gear 4a or any gear in the driving force transmission mechanism.

On the other hand, if the influence of external shock is alleviated, that is, if the gear 4e is subjected to a load equal to or less than a certain rotational torque, the deformed teeth of the gear 4e return to their original state due to this restoring force, and the gear 4e and the gear 4e are restored. 4f will rotate integrally.

According to the present embodiment, the motor 3 to the lens barrel unit 6 can be simply used by using the elastically deformable gear 4e.
Since the driving force can be transmitted to and the impact force from the outside can be absorbed, it is possible to prevent the cost from increasing due to the increase in the number of parts and the driving force transmitting mechanism from increasing in size.

Further, when a leaf spring is used as in the prior art, if a high transmission torque is to be generated,
As described above, it is necessary to make the friction surface of the leaf spring large, and the driving force transmission mechanism becomes large. However, in the present embodiment, a high transmission torque can be generated by changing the material of the gear 4e. Therefore, the driving force transmission mechanism does not increase in size.

(Second Embodiment) A second embodiment of the present invention will be described with reference to FIGS. 6 and 7. In this embodiment,
The present invention relates to a mechanism for adjusting the meshing tooth width of gears in the driving force transmission mechanism of the first embodiment.

FIG. 6 is an exploded perspective view showing the structure of the gear meshing tooth width adjusting mechanism, and FIG. 7 is a view showing the state of adjusting the gear meshing tooth width. Here, the same members as the members described in the first embodiment are designated by the same reference numerals.

The parts of this embodiment different from the first embodiment will be described below. Other configurations are similar to those of the first embodiment.

In FIG. 6, a gear shaft 2a formed on the gear base plate 2 is provided with a spring for urging the gear 4e of the reduction gear train 4 in the upward direction in FIG. 6 (direction for reducing the tooth width in mesh with the gear 4f). 8 (biasing member described in claims) and washer 9
And are incorporated. The gear 4e is arranged on the upper surface of the washer 9, and the gear holding plate 5 is provided on the upper surface of the gear 4e.
Are placed. The thrust adjusting screw 10 (holding member described in the claims of the present application) passes through the hole of the gear holding plate 5 and is fitted into the hole of the gear 4e.

That is, in this embodiment, a mechanism for adjusting the meshing tooth width of the gear 4e of the reduction gear train 4 is newly provided, and the transmission torque can be adjusted by changing the gear meshing tooth width. is there. Here, the operation of transmitting the rotational force of the motor 3 to the lens barrel unit 6 and the operation of absorbing an impact from the outside are the same as those in the first embodiment, and therefore in the present embodiment, the gear meshing tooth width adjustment operation is performed. Will be described only.

The meshing tooth width of the gear 4e is adjusted by rotating the thrust adjusting screw 10 clockwise or counterclockwise. That is, when the thrust adjusting screw 10 is rotated clockwise, the thrust adjusting screw 10 moves downward in FIG. 7 along the lead of the thrust adjusting screw 10. Along with this movement, the gear 4e moves downward in FIG. 7 against the biasing force of the spring 8 and moves to the position shown by the dotted line in the drawing. Thereby, the meshing tooth width of the gear 4e and the gear 4f can be increased.

On the other hand, when the thrust adjusting screw 10 is rotated counterclockwise, the thrust adjusting screw 10 moves upward in FIG. 7 along the lead of the thrust adjusting screw 10. Along with this movement, the gear 4e receives the biasing force of the spring 8 and moves upward in FIG. As a result, the gear 4e
It is possible to reduce the meshing tooth width between the gear and the gear 4f.

Thus, the transmission torque in the driving force transmission mechanism can be adjusted by changing the meshing tooth width of the gear 4e and the gear 4f.

In the present embodiment, the mechanism for adjusting the meshing tooth width of the gear described above moves the gear 4e in the direction of the rotation axis of the gear to change the gear tooth meshing width of the gear with the gear 4f. Therefore, it is not necessary to prepare a plurality of types of gears having different gear tooth thicknesses in order to adjust the transmission torque, and the cost can be reduced. Further, even after the driving force transmission mechanism is assembled, the transmission torque can be easily adjusted only by rotating the thrust adjusting screw 10.

Although the transmission mechanism for transmitting the rotational force of the motor 3 to the lens barrel unit 6 has been described in the above-described first and second embodiments, the present invention may be applied to other transmissions provided in the camera. You may use for a mechanism. Further, the present invention may be used in a transmission mechanism in a device other than a camera.

[0056]

According to the first aspect of the present invention, by forming at least one gear of the gear train with an elastic member, the power of the driving source can be transmitted to the driven member, and When a rotational force of a predetermined rotational torque or more is applied from the driven member side, this gear elastically deforms to prevent the rotational force of a predetermined rotational torque or more from being transmitted to the gear stage on the drive source side. It can absorb impacts from the outside. Further, in the present invention, since at least one gear of the gear train is changed in material, it is possible to prevent an increase in cost and an increase in size of the driving force transmission device due to an increase in the number of parts.

According to the third aspect of the present invention, the transmission torque can be easily adjusted and the transmission torque can be adjusted simply by displacing at least one gear in the rotation axis direction of the gear. Therefore, it is not necessary to prepare a plurality of types of gears having different gear tooth thicknesses, and the cost can be reduced.

Here, the adjusting means is a biasing member for biasing at least one gear in one direction of the rotation axis of the gear,
At least one gear can be constituted by a holding member that pushes the gear against the urging force of the urging member and holds the state of the gear after the displacement. With such a configuration, the meshing tooth width of the gear can be easily changed only by pushing at least one gear by the holding member without disassembling the driving force transmission device.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of a driving force transmission mechanism according to a first embodiment of the present invention.

FIG. 2 is a perspective view of a driving force transmission mechanism according to the first embodiment of the present invention.

FIG. 3 is a perspective view of a driving force transmission mechanism and a lens barrel unit according to the first embodiment of the present invention.

FIG. 4 is a front view of the camera body according to the first embodiment of the invention.

FIG. 5 is a diagram showing a state in which a gear elastically deforms.

FIG. 6 is an exploded perspective view of a mechanism for adjusting a meshing tooth width of a gear according to a second embodiment of the present invention.

FIG. 7 is a side view of a mechanism for adjusting a meshing tooth width of a gear.

FIG. 8 is an exploded perspective view of a clutch mechanism according to a first conventional technique.

FIG. 9 is an exploded perspective view of a clutch mechanism according to a second conventional technique.

FIG. 10 is an exploded perspective view of a clutch mechanism according to a third conventional technique.

FIG. 11 is a perspective view of a unit in which a clutch mechanism is incorporated.

FIG. 12 is a sectional view of a clutch mechanism.

[Explanation of symbols]

1 Driving force transmission mechanism 2 gear base plate 3 motor 4 Reduction gear train 4a, 4b, 4c, 4d, 4e, 4f gears 5 Gear holding plate 6 Lens barrel unit 8 springs 9 washers 10 Thrust adjusting screw

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G03B 17/02 G03B 17/02 F term (reference) 2H020 MA03 MA08 MA09 MC31 2H044 BD14 DD08 2H100 AA33 3J009 DA10 DA16 EA06 EA11 EA25 EB10 EC04 ED02 FA23 3J030 AA01 BA01 BC01 CA01

Claims (6)

[Claims] 1. A drive force transmission device for transmitting the power of a drive source to a driven member via a gear train, wherein at least one gear of the gear train is made of an elastic member and has a predetermined rotational torque. A driving force transmission device, which is elastically deformed when the above rotational force is applied. 2. The driving force transmission device according to claim 1, wherein the at least one gear is incorporated as a gear stage on the driven member side of the gear train. 3. The adjusting device according to claim 1, further comprising adjusting means for displacing the at least one gear in a rotation axis direction of the gear so as to change a meshing tooth width with an adjacent gear. Driving force transmission device. 4. The adjusting means comprises an urging member for urging the at least one gear in one direction of a rotation axis of the gear, and an urging member for pressing the at least one gear against an urging force of the urging member. The driving force transmission device according to claim 3, further comprising: a holding member that moves and holds the state of the gear after the displacement. 5. A camera comprising the driving force transmission device according to claim 1. Description: 6. The camera according to claim 5, wherein the driven member is a lens barrel that can be extended and retracted in the optical axis direction.