JPH06117498A - Friction torque transmission mechanism - Google Patents

Abstract

PURPOSE:To adjust friction torque easily in the friction torque transmission mechanism of a zoom lens driving device by selecting one out of plural recessed parts of different depth in a fixed member, and after engaging the engaging member of a spring receiver with the selected recessed part, changing the space between the fixed member and the spring receiver so as to change the contraction quantity of a spring. CONSTITUTION:The fixed plate 48 of a friction torque adjusting means 46 is provided with round recessed parts 60, 62, 64 of different depth formed concentrically by threes at the interval of 120 deg.. As to the depth, it is so set that the recessed part 60 is deepest, the recessed part 62 is medium, and the recessed part 64 is shallowest. A spring receiving plate 50 is protrusively provided with three pins 66, and the pins 66 are selectively engaged with the recessed parts 60, 62, 64. That is, if the recessed part 60 is selected, the pin 66 is fit in deep, and the space between the fixed plate 48 and the spring receiving plate 50 is narrowed, so that the spring 44 is extended, and friction torque becomes small. Friction torque becomes larger in the order of the recessed parts 62, 64.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a friction torque transmission mechanism, and more particularly to a friction torque transmission mechanism applied to a zoom lens driving device of a camera.

[0002]

2. Description of the Related Art Conventionally, a motor for driving a zoom lens device of a camera is provided with a friction torque transmission mechanism, and an excessive load is applied to a follower animal or the follower animal hits a mechanical stopper. At times, the friction torque transmission mechanism releases the rotational force of the motor to prevent its impact from being directly applied to the motor, thus protecting the motor.

FIG. 5 shows a conventional friction torque transmission mechanism. A gear mounting shaft 3 is fixed to a spindle 2 of the drive motor 1, and a driving force transmitting gear 4 is loosely fitted to the gear mounting shaft 3. The driving force transmitting gear 4 includes a spring support plate 5 fixed to the tip of the gear mounting shaft 3.
And a pressing plate 6 that is loosely fitted to the gear mounting shaft 3 and is pressed against the flange portion 8 of the gear mounting shaft 4 by the urging force of a spring 7 that is inserted and arranged. Also, it rotates by the frictional force with the pressing plate 6.

Therefore, when a load larger than the frictional force is applied to the driving force transmitting gear 4, the flange portion 8 and the pressing plate 6 run idle with respect to the driving force transmitting gear 4.
It is possible to protect the drive motor 1 without transmitting an excessive load to the drive motor 1. In this friction torque transmission mechanism, a plurality of washers are inserted between the spring 7 and the pressing plate 6, and the spring biasing force is adjusted by increasing or decreasing the number of washers.

FIG. 6 shows another conventional friction torque transmission mechanism. This type of friction torque transmission mechanism includes a double nut 1 screwed onto a gear mounting shaft 10.
The amount of tightening of Nos. 2 and 12 is adjusted to adjust the biasing force of the spring 14, and the frictional force of the driving force transmitting gear 18 with respect to the flange portion 16 and the pressing plate 24 is adjusted.
The gear mounting shaft 10 is fixed to a spindle 22 of a drive motor 20, and the drive force transmission gear 18 is provided.
Is urged by the spring 14 via the pressing plate 24.

[0006]

However, in order to adjust the friction torque by the friction torque transmission mechanism shown in FIG. 5, a plurality of washers are inserted between the spring 8 and the pressing plate 7, and the number of the washers is set. Since it has to be adjusted by increasing and decreasing, there is a drawback that it takes time and effort.

Further, in order to adjust the friction torque by the friction torque transmission mechanism shown in FIG. 6, it is necessary to adjust the tightening amount of the double nuts 12, 12, which is troublesome and the double nut 12, 12
Since it uses, there is also a drawback that the cost becomes high. The present invention has been made in view of such circumstances, and an object of the present invention is to provide a friction torque transmission mechanism that can easily adjust the friction torque without trouble.

[0008]

In order to achieve the above object, the present invention provides a driving force transmitting gear loosely fitted to a drive shaft of a motor, a spring inserted through the drive shaft, and a drive shaft. Friction adjusting means provided at the tip end portion for generating an urging force to the spring and pressing and abutting the drive force transmitting gear to the drive shaft by this urging force, and the drive force transmitting gear and the drive shaft. A friction torque transmitting mechanism for transmitting the rotational force of the drive shaft to the drive force transmitting gear by the friction force of the friction adjusting means, wherein the friction adjusting means is fixed to the tip end portion of the drive shaft and has a depth on the spring side surface thereof. And a fixing member having a plurality of recesses different from each other, or an engaging member, and a fixing member movably provided with respect to the drive shaft. Recess An engaging member to be engaged, or a spring receiving member in which concave portions having different depths are formed to be engaged with the engaging member of the fixing member, and the engaging member is provided between the fixing member and the spring receiving member. Is engaged with a recess having a selected depth of the plurality of recesses to change the distance between the fixing member and the spring receiving member, thereby adjusting the biasing force of the spring.

[0009]

According to the present invention, the engaging member projectingly formed on the spring receiving member is engaged with the recess having a selected depth among the plurality of recesses having different depths formed in the fixing member, and the fixing member is fixed. The distance between the spring and the spring receiving member is changed to change the contraction amount of the spring. Thus, the urging force of the spring can be easily adjusted, so that the friction torque of the driving force transmitting gear can be easily adjusted without any trouble.

Further, an engaging member is formed on the fixing member, a plurality of recesses having different depths are formed on the spring receiving member, and a recess having a selected depth among the plurality of recesses of the spring receiving member is formed. The engaging member of the fixing member may be engaged to change the distance between the fixing member and the spring receiving member.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a friction torque transmitting mechanism according to the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 shows a friction torque transmission mechanism 3 according to the present invention.
It is sectional drawing which shows the Example of No. 0. To the spindle 34 of the drive motor 32, a gear mounting shaft 38 having a flange portion 36 formed at the base thereof is fixed on the concentric shaft. A driving force transmitting gear 40 is loosely fitted on the gear mounting shaft 38, and the driving force transmitting gear 40 is meshed with a driven gear of a zoom lens driving device (not shown). Also,
A pressing plate 42 and a spring 44 are inserted through the gear mounting shaft 38, and a friction torque adjusting means 46 is mounted on the left end of the gear mounting shaft 38 in the figure.

The friction torque adjusting means 46 is
It is composed of a fixed plate 48 and a spring receiving plate 50. A shaft 52 is projectingly formed at the center of the side surface 48a of the fixed plate 48, and the shaft 52 has a round hole 56 of the gear mounting shaft 38 through an opening 54 formed at the center of the spring receiving plate 50. Stuck to. As shown in FIG. 2, arcuate slots 58, 58, 58 are formed in the fixing plate 48 on the concentric circles at intervals of 120 °. In addition, the side surface 48a of the fixing plate 48
The circular recesses 60, 62, 64 having different depths are concentric with the slot 58 and are adjacent to the slot 64.
And three are formed with an interval of 120 ° between them. The depths are as follows: recess 60 = deep, recess 62 = middle, recess 64 = shallow.

The spring receiving plate 50, as shown in FIG.
It is movably arranged along the shaft 52. The right side surface 50a of the spring receiving plate 50 in the figure serves as a support surface for the spring 44, and the three pins 66, 66, 66 are concentrically arranged on the left side surface thereof as shown in FIG. And 12
The protrusions are formed at an interval of 0 °. These pins 66,
66, 66 are recesses 60, 62, 64 of the fixing plate 48.
It is formed at a position to be engaged with three recesses of the same depth selected from among them. Further, round recesses 68, 68, 68 are formed concentrically between the pin 66 and the adjacent pin 66. The recesses 68, 68, 68 are tripod pins of a moving jig 70 (see FIG. 4) which is inserted from the outside of the friction torque adjusting means 46 through the long holes 58, 58, 58 of the fixing plate 48 during friction torque adjustment. 72 is engaged.

Next, the operation of the friction torque transmission mechanism 30 constructed as described above will be described. When the drive motor 32 is driven to rotate the gear mounting shaft 36, the driving force transmitting gear 40 causes the flange portion 36 and the pressing plate 42 to move.
And the driven gear of the zoom lens device that is meshed with the driving force transmitting gear 40 is rotated. Further, when a load greater than the frictional force is applied to the driven gear side while the driven gear is rotating, that is, the driving force transmitting gear 40
Is stopped suddenly, the flange portion 36 and the pressing plate 42
Slides with respect to the driving force transmission gear 40, so that the drive motor 32 can be protected.

Next, the friction torque transmission mechanism 3
A method of adjusting the friction torque of 0 will be described. In the friction torque adjusting means 46 shown in FIG. 1, the pins 66, 66, 66 of the spring receiving plate 50 are the recesses 6 of the fixing plate 48.
Since it is engaged with 0, 60, 60, that is, with the recess 60 deeper than the other recesses 62, 64, the distance between the fixed plate 48 and the spring receiving plate 50 is narrow. As a result, the contraction amount of the spring 44 is small, so that the driving force transmission gear 40
The urging force that presses against the flange portion 36 is weak. Therefore, the friction torque can be reduced by engaging the pin 66 with the recess 60.

Next, the case of increasing the friction torque will be described. The tripod pin 72 of the moving jig 70 shown in FIG. 4 is engaged with the recesses 68, 68, 68 of the spring receiving plate 50 from the outside of the friction torque adjusting means 46 via the long holes 58, 58, 58 of the fixing plate 48. To meet. Then, the moving jig 70 is pushed in to slide the spring receiving plate 50 in the direction of the driving force transmitting gear 40 against the urging force of the spring 44, and the pins 66, 66, 66 of the spring receiving plate 50.
And the engagement between the recesses 60, 60, 60 of the fixing plate 48 are released. Then, in this state, the moving jig 70 is rotated to rotate the spring receiving plate 50 by a predetermined angle, so that the pins 66, 66, 66 are recessed in the fixing plate 48.
2 or the recesses 64, 64, 64.

As a result, the fixing plate 48 and the spring receiving plate 50 are formed.
Since the distance between and is wider than that at the time of engagement with the recess 60, the contraction amount of the spring 44 is increased. Therefore, the urging force that presses the driving force transmitting gear 40 against the flange portion 36 becomes stronger, so that the friction torque can be increased.
Thus, in this embodiment, the pin 66 of the spring receiving plate 50 is
Since the friction torque can be adjusted only by engaging the selected recess 60, (62, 64) of the recesses 60, 62, 64 of the fixing plate 48, the drive force transmitting gear 40
The friction torque of can be easily adjusted without trouble.

In this embodiment, the fixed plate 48 is provided with the recess 6
0, 62, 64 are formed, and the spring receiving plate 50 has pins 66,
Although the protrusions 66, 66 are formed, the present invention is not limited to this, and the pins 66, 66, 66 may be formed on the fixed plate 48 and the recesses 60, 62, 64 may be formed on the spring receiving plate 50. good. Further, in the present embodiment, the spring receiving plate 50 is slid along the shaft 52 of the fixed plate 48, but the present invention is not limited to this, and the shaft 52 is shortened so that the gear mounting shaft 38 has a round shape. The spring receiving plate 50 may be fitted in all the holes 56 so that the spring receiving plate 50 can slide along the gear mounting shaft 38.

[0019]

As described above, according to the friction torque transmission mechanism of the present invention, a recess having a depth selected from a plurality of recesses formed in the fixing member and having different depths is provided.
Since the urging force of the spring is adjusted by engaging the engaging member projectingly formed on the spring receiving member, it is possible to easily adjust the friction torque of the driving force transmitting gear without any trouble.

Further, the engaging member is formed on the fixing member, and a plurality of concave portions having different depths are formed on the spring receiving member, and the fixing member is formed on the concave portion of the spring receiving member having a selected depth. The engaging member may be engaged to change the distance between the fixing member and the spring receiving member.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of a friction torque transmission mechanism according to the present invention.

FIG. 2 is a view taken along the line 2-2 in FIG.

FIG. 3 is a view taken along the line 3-3 in FIG.

FIG. 4 is a perspective view showing an embodiment of a moving jig applied to the friction torque transmission mechanism according to the present invention.

FIG. 5 is a sectional view showing a first embodiment of a conventional friction torque transmission mechanism.

FIG. 6 is a sectional view showing a second embodiment of a conventional friction torque transmission mechanism.

[Explanation of symbols]

 30 ... Friction torque transmission mechanism 32 ... Drive motor 36 ... Flange portion 38 ... Gear mounting shaft 40 ... Power transmission gear 44 ... Spring 46 ... Friction torque adjusting means 48 ... Fixed plate 50 ... Spring receiving plate 60, 62, 64 ... Recess 66 ... Pin 70 ... Moving jig 72 ... Tripod pin

Claims (1)

[Claims] 1. A drive force transmitting gear that is loosely fitted to a drive shaft of a motor, a spring that is inserted through the drive shaft, and a spring that is provided at the tip of the drive shaft and that generates a biasing force to the spring. Friction adjusting means for pressing and abutting the driving force transmitting gear against the drive shaft by a force, and a frictional force between the driving force transmitting gear and the driving shaft applies a rotational force of the driving shaft to the driving force transmitting gear. A friction torque transmitting mechanism for transmitting the friction adjusting means, wherein the friction adjusting means is fixed to a tip end portion of the drive shaft, and a recessed portion having a different depth or a plurality of engaging members is formed on a side surface thereof on a spring side. An engaging member that is provided so as to be movable with respect to the drive shaft and has a support surface for the spring formed on one side surface thereof and that is engaged with a recess of the fixing member on the other side surface; Joint section A spring bearing member formed with concave portions having different depths to be engaged with the material, wherein the engaging member is a concave portion having a depth selected from the plurality of concave portions between the fixing member and the spring receiving member. A friction torque transmission mechanism, characterized in that the biasing force of a spring is adjusted by engaging and changing the distance between a fixing member and a spring receiving member.