JPH0862688A - Clutch structure - Google Patents

Abstract

PURPOSE: To provide compact clutch structure by which the number of parts is reduced. CONSTITUTION: A driving gear 10 and a spool for winding up a film 14 are provided on an identical shaft so as to be freely rotated. A wire spring 12 is formed into a circular-arc shape and the hook parts 28A and 28B of both end parts thereof are formed to be bent. At an assembling time, the spring 12 is made to contract from an expanded state. Then, the hook part 28A is engaged with a groove 30 formed between a projection piece 26A and a projection piece 26B on the spool 14 side and the hook part 28B is engaged with a groove 32 formed between the projection piece 26A and a projection piece 26D. When the gear 10 is arranged on the upper flange 20 of the spool 14, the circumferential part of the spring 12 is made to press-contact with the inside circumferential surface of the gear 10 by the pressing force thereof. When torque added to the spool 14 is within a range that it is not over the torque by frictional force generated between the gear 10 and the spring 12, the spool 14 is integrally rotated with the gear 10 by the frictional force.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a clutch structure, and more particularly to a clutch structure for transmitting a rotational driving force from an electric motor to a film winding spool provided in a camera or a film scanner device.

[0002]

2. Description of the Related Art When a film that is conveyed at a constant speed by a capstan roller or the like is wound on a film winding spool, the winding speed changes depending on the winding diameter. Is provided. A conventional clutch structure of this type is shown in FIG. In this clutch structure, a felt 3 is interposed between a drive gear 1 rotated by a rotational force from an electric motor and a spool gear 2 for winding a film, and
The slip surface 1A of each of the drive gear 1 and the spool gear 2,
2A is pressed against the felt 3 by the urging force of the spring 4.

In the clutch structure thus constructed,
Until a predetermined torque is applied to the spool gear 2, the spool gear 2 rotates integrally with the drive gear 1 due to the frictional force with the felt 3. Then, when a torque larger than the above-mentioned torque is applied to the spool gear 2, the spool gear 2 will move to the drive gear 1
Rotate while sliding against. As a result, the film is smoothly wound on the spool without applying excessive tension.

[0004]

However, in the conventional clutch structure, the spring 4 is required, so the thickness is increased by the height of the spring, and the contact area with the felt 3 must be wide, so that it is large in size. There is a drawback that Further, in the conventional clutch structure, since the spring 4 for applying the biasing force and the felt 3 for generating the frictional force are separate parts, the number of parts is increased.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a compact clutch structure having a small number of parts.

[0006]

In order to achieve the above object, the present invention provides a driving member which is rotated by a rotational force from a driving source and a driven member which is rotatably provided coaxially with the driving member. And provided between the driving member and the driven member,
An arc-shaped wire spring whose one end is engaged with one of the driving member and the driven member and whose peripheral part is pressed against the other by its urging force to generate a predetermined frictional force with the other. When the torque applied to the driven member exceeds the torque due to the frictional force, the driven member slides with respect to the driving member.

[0007]

According to the present invention, the end portion of the wire spring member is engaged with one member of the driving member and the driven member, and the peripheral portion of the wire spring member is pressed against the other member by its urging force. In this way, a predetermined frictional force is generated between the other member. As a result, when the torque applied to the driven member is within the range that does not exceed the torque due to the frictional force, the driven member rotates integrally with the driving member due to the frictional force, and the torque exceeds the torque due to the frictional force. If so, the driven member slides with respect to the drive member. in this way,
In the present invention, since the linear spring member constitutes the clutch, the clutch can be miniaturized, and since the linear spring member is provided with the member for applying the urging force and the member for generating the frictional force, the number of parts is small. Become.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the clutch structure according to the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is a structure showing an embodiment in which the clutch structure according to the present invention is applied to a film winding spool of a film scanner,
FIG. 2 is an assembled perspective view showing an embodiment of the clutch structure.

As shown in FIG. 1, the film scanner is a film 1 sent from a film cartridge 100.
02 is conveyed at a constant speed by a capstan 104 and a pinch roller 106, and the film 102 is wound up on a film winding spool 14 driven by an electric motor 108. The capstan 104 and the film winding spool 14 The frame image of the film 102 that passes between and is scanned. That is, the frame image is illuminated by the light source lamp 110, the transmitted image light is reflected by the reflection mirror 112, and is formed on the image forming surface of the line sensor 114. The voltage signal output from the line sensor 114 is used as the image processing device 116.
After being subjected to image processing by, the image is output to the monitor TV 118, and the frame image is displayed on the monitor TV 118.

As shown in FIG. 2, the clutch applied to the film scanner comprises a driving gear 10, a wire spring 12, and a film winding spool 14 which is a driven member. The drive gear 10 is formed in a ring shape and meshes with the gear 16 shown in FIGS. 1 and 3, and the rotational force from the electric motor 108 shown in FIG. 1 is transmitted from the gear 16. .

The film winding spool 14 is rotatably provided coaxially with the axis 18 of the drive gear 10. The spool 14 has a take-up portion main body 24 formed between flanges 20 and 22 formed at an upper portion and a lower portion. The upper flange 20 of the spool 14 is shown in FIG.
As shown in FIG. 4, four projecting pieces 26A formed in an arc shape,
26B, 26C, and 26D are formed in a protruding manner.

The wire spring 12 is formed in an arc shape, and
Hook portions 28A and 28B are bent inward at both ends thereof. When the clutch is assembled, the wire spring 12 is contracted as shown by the solid line from the expanded state (original state) shown by the chain double-dashed line in FIG. Groove 3 between 26B
0, and the one hook portion 28B has the protrusion 26A.
Is engaged with the groove 32 between the projection piece 26D and the projection piece 26D. Further, the peripheral portion of the wire spring 12 has the drive gear 10 arranged on the upper flange 20 of the spool 14 so that the drive gear 1 is
It is pressed against the inner peripheral surface 10A of 0 by its urging force (restoring force). As a result, a predetermined frictional force due to the urging force of the wire spring 12 is generated between the drive gear 10 and the wire spring 12.

Next, the operation of the clutch structure constructed as described above will be described. Rotational force from the electric motor 108 is transmitted to the drive gear 10 via the gear 16, and the drive gear 10 is rotated to start winding the film 102. Then, while the film 102 is not wound around the film winding spool 14, the drive gear 10
The film winding spool 14 rotates integrally with the drive gear 10 due to the frictional force between the film spring 12 and the wire spring 12.

Next, the film 102 is conveyed at a constant speed by the capstan 104 shown in FIG. 1 and reaches the film winding spool 14. On the other hand, since the film winding spool 14 rotates at a constant speed, the winding speed of the film 102 also changes with the change of the winding diameter of the film 102, but it is always faster than the conveying speed of the capstan 104. It is set to wind the film 102 at a speed. Therefore, when the film 102 winds around the film winding spool 14, a speed difference is generated between the drive gear 10 and the film winding spool 14, and the driving gear 10 and the film winding spool 14 rotate while sliding relative to each other. At this time, the film 102 is applied with an appropriate tension generated by the frictional force between the drive gear 10 and the wire spring 12, and the film winding spool 1
It is smoothly wound into 4.

As described above, in this embodiment, since the wire spring 10 constitutes the clutch, the clutch can be downsized, and
Since the wire spring 10 is provided with the member for applying the urging force and the member for generating the frictional force, the number of parts is reduced. In the present embodiment, for example, when the drive gear 10 is rotated clockwise in FIG. 4 to wind up the film,
Gap a between the hook portion 28A of the wire spring 12 and the projecting piece 26B
Is set to be smaller than the gap b between the hook portion 28B on the other side and the protruding piece 26A. Drive gear 10 set in this way
When is rotated, the hook portion 28A comes into contact with the projecting piece 26B before the hook portion 28B comes into contact with the projecting piece 26A.
However, if gap a> gap b is set, the hook portion 28B
Comes into contact with the protruding piece 26A first, and the wire spring 12 is connected to the drive gear 1
A force of 0 is applied in the direction of expansion. As a result, the frictional force between the drive gear 10 and the wire spring 12 increases, and the spool 14 becomes less slippery with respect to the drive gear 10, so that the film 102 can be wound up under an excessive tension. May be damaged. Therefore, in order to prevent such a problem, the gaps a and b should be a <
b.

When the drive gear 10 is rotated counterclockwise to wind up the film, the clearance c> the clearance d may be set. In this embodiment, the wire spring 12 is engaged with the spool 14 side so as to be in pressure contact with the drive gear 10 side. However, the present invention is not limited to this, and the wire spring 12 is brought into pressure contact with the spool 14 side so as to be in contact with the drive gear 10. You may make it engage with the side.

In this embodiment, the wire spring 12 is pressed against the drive gear 10 by the urging force of the wire spring 12 in the expansion direction.
The present invention is not limited to this, and the wire spring may be pressed against the urging force in the contracting direction.

[0018]

As described above, according to the clutch structure of the present invention, the end portion of the wire spring member is engaged with one of the drive member and the driven member, and the peripheral portion of the wire spring member is engaged with the end portion of the wire spring member. Since the other member is pressed against the other member by the urging force, a predetermined frictional force is generated between the other member,
The clutch can be downsized and the number of parts can be reduced.

[Brief description of drawings]

FIG. 1 is a structural diagram showing an embodiment in which a clutch structure according to the present invention is applied to a film scanner.

FIG. 2 is an assembled perspective view showing an embodiment of a clutch structure according to the present invention.

FIG. 3 is a longitudinal sectional view of the clutch structure shown in FIG. 1 after assembling.

FIG. 4 is a top view including a partial break after assembling the clutch structure shown in FIG.

FIG. 5 is a vertical sectional view showing an example of a conventional clutch structure.

[Explanation of symbols]

 10 ... Drive gear 12 ... Wire spring 14 ... Film winding spool 28A, 28B ... Hook portion 30, 32 ... Groove

Claims (1)

[Claims] 1. A drive member that is rotated by a rotational force from a drive source, a driven member that is rotatably provided coaxially with the drive member, and a drive member that is provided between the drive member and the driven member. The end portion is engaged with one of the member or the driven member,
On the other hand, an arc-shaped wire spring member whose peripheral portion is pressed by the urging force to generate a predetermined frictional force with the other, and the torque applied to the driven member is the torque generated by the frictional force. A clutch structure in which the driven member slides with respect to the driving member when it exceeds.