JP3285075B2 - Paper transport device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shape of a close contact coil spring for fixing a driven roller incorporated in a paper transport mechanism.

[0002]

2. Description of the Related Art The configuration of a portion for transporting paper used in OA equipment such as a printer, a copying machine, and a facsimile is such that a constant load is applied to a driven roller by applying a constant load to a driven roller.
The conveyance force is generated by the rotation of the driving roller. As a method of fixing the driven roller, a method of fixing a linear spring as a beam has been used.

[0003] As an example of a fixed structure of the driven roller in this case, there is a structure as shown in FIG. That is, the side surface of the driven roller 13 is regulated by the surface of the fixing member 14, the inner cylindrical portion of the driven roller 13 is received by the linear spring 15, and the linear spring 15 is bent to obtain a pressing force 17 on the driving roller 16. .

[0004] The above-described wire spring has the following problems. First, there is no freedom in setting the pressing force of the driven roller to the driving roller. In other words, in order to weaken the pressing force, it is necessary to reduce the diameter of the wire spring or to lengthen the wire spring. Therefore, the work is difficult or large space is required at the time of assembly. Second, with long-term use, the wire spring is plastically deformed, and the pressing force on the drive roller is lost.

In order to solve such a problem, a contact coil spring has been used as a substitute for a wire spring. That is, by using a close contact coil spring,
The pressing force can be adjusted over a wide range, and the reliability can be improved even during long-term use.

However, the close contact coil spring having a simple shape has a characteristic of converting its own rotational movement into a linear movement in the longitudinal direction with the fulcrum as a base point.
By the way, the driven roller makes a rotational movement with the conveyance of the sheet, and since this rotational force is transmitted to the close contact coil spring, the close contact coil spring also causes a rotational movement. At this time,
Since the rotational motion is converted into a linear motion based on the fulcrum of the fixed coil spring of the fixed member, there is a problem that the end surface of the fixed coil spring gets over the barrier of the fixed member.

In the prior art using the close contact coil spring as shown in FIG. 3, the linear movement of the close contact coil spring 11 is restricted only by the barrier A. At this time, if the vertical component force of the propulsion force consisting of the linear motion is larger than the vertical component force of the frictional force generated between the barrier A of the fixing member 12 and the end face B of the close contact coil spring 11, the close contact coil spring 11 12 barriers A
, The linear motion is further continued, and the end surface C of the contact coil spring 11 on the opposite side comes off from the fulcrum D of the fixing member 12.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of such a problem.
An object of the present invention is to provide a sheet transport structure that can easily prevent the driven roller from falling off when a contact coil spring is used to fix the driven roller.

[0009]

That is, in order to attain the object, the present invention has a stepped shape added to the outer surface of the close contact coil spring to prevent the close contact coil spring from dropping off from the fixing member. .

[0010]

FIG. 1 is a right side view (a) and a sectional view (b) showing an embodiment of the present invention. FIG. 2 is a front view (a) and a side view (b) of a contact coil spring according to one embodiment of the present invention.
It is.

As shown in FIG. 1, a drive roller 1 is press-fitted into a drive shaft 2 which is stretched in a direction perpendicular to a sheet conveying direction (not shown). On the other hand, the driven roller 3 is disposed so as to face the driving roller 1, and has a contact coil spring 4, which will be described later, as a rotation axis.
Supported on the part. This contact coil spring 4 is
Closely wound right-handed along the axis from left to right
It is formed as a coil spring.
The lower part in the winding direction is wound thicker than other winding diameters
And the vertical wall 51 of the fixing member 5 located on the left side of the drawing.
It is placed so as to be located at the intersection 52.

[0012] The thus-configured sheet transport apparatus first on the central axis of the contact spring 4 is engaged so as to coincide substantially with the central axis of the driven roller 3, both of the fixing member 5
It is attached to a position facing the drive roller 1 so as to be placed on the side portion . Thereby, the contact coil spring 4 is driven.
Deflected concavely toward the roller 1 and driven by the reaction force
The roller 3 is pressed against the peripheral surface of the drive roller 1, the sheet 6 is conveyed I with the rotation of the driving roller 1, driven rollers also the sheet 6 is rotated together driving roller 1 and driven roller
3 while being conveyed.

As shown in FIG. 2, the close contact coil spring 8 has a helical shape. When the coil spring 8 is rotated once with the sharp fulcrum 9 as a base, a groove 10 (a) corresponding to the fulcrum 9 is formed.
From 10 (a) to 10 (b), and from 10 (b) to 10 (c) for each further revolution, from 10 (c) to 1
When the spring itself rotates so as to gradually move to 0 (d), it moves in the spring axis direction.

When this is applied back to FIG. 1, the rotational motion given to the driven roller 3 by the conveyance of the paper 6 is as follows.
It is transmitted to the close contact coil spring 4, and the close contact coil spring 4 rotates around its axis. As a result, the contact coil spring 4
Moves to the left in the axial direction. However, as explained before, contact spring 4, movement in the axial direction is regulated by the stepped shape of its adhesion coil spring 4 with the rotation of the driven roller 3 is rotated about its axis
Even if it does not move in the axial direction, the other side of the fixing member 5
It does not deviate et al.

[0015]

As described above , according to the present invention , the lower part of the close contact coil spring in the winding direction is smaller than the other parts.
A large-diameter stepped portion is provided, so that
Even if the close contact coil spring rotates,
Not only will it not fall off,
However, the close contact coil spring does not lose its spring characteristics.
And always maintain a reliable transport action by holding the paper
Can be.

[Brief description of the drawings]

FIG. 1 is a right side view (a) and a sectional view (b) of one embodiment of the present invention.

FIG. 2 is a front view (a) and a side view (b) of a close contact coil spring according to one embodiment of the present invention.

FIG. 3 is a cross-sectional view of a related art using a close contact coil spring.

FIG. 4 is a sectional view of a conventional technique using a wire spring.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 drive roller 2 drive shaft 3 driven roller 4 contact coil spring 5 fixing member 6 paper 7 rotational force 8 contact coil spring 9 fulcrum 10 (a) groove of contact coil spring 10 (b) groove of contact coil spring 10 (c) groove of contact coil spring 10 (D) Groove of contact coil spring 11 Contact coil spring 12 Fixing member 13 Follower roller 14 Fixing member 15 Wire spring 16 Drive roller 17 Pressing force 51 Vertical wall located on left side of fixing member 5 52 Vertical wall located on left side of fixing member 5 Intersection with 51

Claims (1)

(57) [Claims] 1. A contact coil having both ends suspended from a fixing member
A driven roller having a spring as a support shaft is bent by the close contact coil spring.
By using the reaction force, pressure is applied to the drive roller.
In the paper transport device of the contact type, the suspension portion on the lower side in the winding direction of the close contact coil spring
Provided a stepped portion with a larger diameter than the other winding diameters.
And a paper transport device.