JPH05286587A - Paper feeding device - Google Patents

Abstract

PURPOSE:To stabilize paper-feeding start timing and conveying state at the of paper feeding in a paper feeding device. CONSTITUTION:A tip end part of a sheet immediately after separation by a paper feed roller 1 and a separation roller 3 is strongly held between a projection of a push-out roller 20 and a push-out assisting roller 21 and the push-out roller 20 is rotated, and the sheet is pushed out till the sheet tip end is delivered into the paper feed roller 1 by a predetermined amount so that lack in delivering and conveying force at start of paper feeding is compensated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet feeding device for separating sheets fed one by one and feeding them in a sheet feeding direction, and more particularly to feeding and separating a sheet by a sheet feeding roller and a separating roller. Alternatively, the present invention relates to a sheet feeding device that is performed by combining friction plates.

[0002]

2. Description of the Related Art In facsimiles, image scanners, etc., a sheet feeding device having a structure as shown in FIGS. 6 to 8 is known as a means for taking paper sheets (original or paper) one by one into the apparatus. There is.

This paper feeding apparatus has a separating and feeding mechanism mainly composed of a rubber feeding roller 1 and a feeding roller 2 and a silicon rubber separating roller 3 as shown in FIG. 6 (schematic front view). Reference numerals 4 and 5 are shafts driven by a motor (not shown). Although only one set of this separating / feeding mechanism is shown, a required number of similar mechanisms are arranged in parallel on the shafts 4 and 5 according to the maximum width of the paper sheet to be handled.

The paper feed roller 1 and the feed roller 2 are integrated as a paper feed unit 6, and FIG. 7 is a plan view thereof. The paper feed roller 1 is directly connected to the shaft 4, and the shaft 4
Rotate with. The feed roller 2 is axially attached to a pair of arms 7 that can swing up and down with a shaft 4 as a fulcrum, and the rotation of the shaft 4 is transmitted via a belt 8. The paper feeding unit 6 is connected via a shaft 9 to a mechanism (not shown) for swinging the paper feeding unit 6 up and down with the shaft 4 as a fulcrum.

In FIG. 6, the separation roller 3 is axially attached to a pair of arms 10 which can swing around a shaft 5 as a fulcrum, and is pressed against the paper feed roller 1 by the action of a spring (not shown) provided in the arm 10. Be done. Further, the rotation of the shaft 5 is transmitted to the separation roller 3 via the belt 11.

FIG. 8 is a schematic side view for explaining the operation of the separating and feeding mechanism. The shafts 4 and 5 are driven to rotate the paper feed roller 1 and the separation roller 3 in the directions shown by the arrows in the figure. Further, the paper feed unit 6 is rotated downward with the shaft 4 as a fulcrum, and the feed roller 2 is pressed against the paper sheet 14 on the tray 15. Then, the paper sheet 14 is sent toward the paper feed roller 1 and the separation roller 3 by the feed roller 2, separated by the action of the paper feed roller 1 and the separation roller 3 one by one from the upper layer, and the paper feed roller 1 The paper is conveyed in the paper feeding direction (leftward in the figure).

[0007]

SUMMARY OF THE INVENTION A sheet feeding apparatus configured to separate and feed a sheet by the difference in frictional force between the sheet feeding roller and the sheet of the separating roller as described above has a sheet feeding start timing. Also, there is a problem that the transport state at the start of sheet feeding tends to be unstable. This is because slippage of the paper feed roller is likely to occur when the leading edge of the separated paper sheet is taken up by the paper feed roller, and the feeding force by the paper feed roller is weak while the take-up amount is small. This is because the speed becomes slow, and paper skew or meandering easily occurs.

There is also known a paper feeding device for separating and feeding paper sheets by using a combination of a paper feeding roller and a fixed friction plate instead of a pair of rollers, but this device also has the same problem. ..

The above-mentioned problem is adversely affected in the quality of the leading end portion of the read image or the recorded image when the document is fed by an image scanner or the like or the paper is fed by a printer or the like.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a paper feeding device which solves the above problems at the start of paper feeding.

[0011]

In order to solve the above-mentioned problems, the present invention separates the stacked sheets one by one by a combination of a paper feed roller and a separation roller or a friction plate and conveys them in the paper feed direction. In the paper feeding device, a pair of members for gripping the leading end portion of the separated paper sheets and sending out the paper sheets in the paper feeding direction by a certain amount at the same speed as the conveyance speed by the paper feeding roller, and a pair of these members. And a means for driving at least one member of the above.

[0012]

With the above-described structure, the present invention assists the feeding of the separated sheets to the sheet feeding roller and the conveyance of the sheets during the period when the feeding amount is small, and reduces the variation in the timing of starting the sheet feeding. In addition, it is possible to stabilize the sheet conveyance state at the start of sheet feeding.

[0013]

EXAMPLE A sheet feeding device according to an example of the present invention will be described below.
Description will be made with reference to FIGS. 1 to 4. Note that, in each drawing, the portions denoted by the same reference numerals as those in FIGS. 6 to 8 are equivalent portions, and therefore the description thereof is based on the description of the conventional art.

FIG. 1 is a schematic front view showing the structure of the separating and feeding mechanism of the sheet feeding device and its surroundings. In this paper feeding device, a rubber pushing roller 20 for assisting the feeding / conveying of the sheet at the time of starting the paper feeding by the separation feeding mechanism is provided.
It is provided at positions symmetrical to both sides of the paper feed roller 1. Also,
The rubber push-out auxiliary roller 21 that follows the push roller 20 while sandwiching the paper sheet is provided with the left and right arms 10 and 10.
Is pivoted on.

Reference numeral 22 is a roller 20 for pushing out from the shaft 4.
It is an electromagnetic clutch for controlling the rotation transmission to the. The electromagnetic clutch 22 is, as shown in FIG. 2, a hub 23 fixed to the shaft 4 and a mechanically free hub 23. However, when the electromagnetic clutch 22 is energized, the hub 23 is generated by a magnetic force.
It has an armature hub 24 which rotates therewith. The pushing roller 20 is press-fitted and fixed to the armature hub 24. Reference numeral 25 is a detent for preventing the main body of the electromagnetic clutch 22 from rotating with the shaft 4.

In relation to the push roller 20, as shown in FIG. 3, a stopper 27 for stopping the rotation of the push roller 20 at a predetermined angle is provided. Since the stopper 27 needs to have elasticity, it is formed of a leaf spring or the like. The push-out roller 20 is a roller having a substantially circular cross section, but as shown in an enlarged view in FIG. 4, a protrusion 29 is provided at one location on the peripheral surface. When the electromagnetic clutch 22 is not energized, the tip of the stopper 27 engages with the protrusion 29, so that the pushing roller 20 is stopped at the angle shown in FIG.

Although not shown, the shaft 4,
It goes without saying that there is an electronic circuit for controlling the operation of the drive motor of No. 5, the electromagnetic clutch 22 and the like.

The operation of the sheet feeding device configured as described above will be described below. The shafts 4 and 5 are driven by operating a motor (not shown), and the paper feeding unit 6 is rotated downward together with the pushing roller 20 and the electromagnetic clutch 22 by a mechanism (not shown) to move the feed roller 2 onto the tray 15. It is pressed against the paper sheet 14. The push-out roller 20 is stopped at the angle shown in FIG. 4, and there is a gap between the push-out roller 20 and the push-out auxiliary roller 21 that does not hinder the passage of the paper sheet.

The electromagnetic clutch 22 is energized at the timing when the uppermost one sheet 14 is separated and starts to be fed into the sheet feeding roller 1, and the armature hub 24 is connected to the hub 23, so that the pushing roller 20 is attached. Shaft 4
Rotation is transmitted. As a result, the extrusion roller 20
It starts to rotate at the same speed as the paper feed roller 1 against the braking force due to the engagement between the protrusion 29 and the stopper 27. The push-out roller 20 rotates from the angle shown in FIG. 4 by θ1, and from the time when the push-out roller 20 is rotated by θ1 between the protrusion 29 and the push-out auxiliary roller 21, the uppermost sheet 14 that is about to be fed into the feed roller 1.
Until the tip of the paper is strongly pinched and further rotated by θ2, only the separated uppermost paper sheet 14 is fed in the paper feeding direction (Fig. 3).
Then push strongly to the left). As a result, the shortage of the sheet feeding force by the sheet feeding roller 1 and the shortage of the conveying force by the sheet feeding roller 1 until the leading edge of the sheet is fed by a certain amount are compensated, and the feeding start timing and the feeding start time The paper transport state of is stable.

When the pushing roller 20 rotates by (360-θ2: minute angle) degrees from the angle shown in FIG. 4, the energization of the electromagnetic clutch 22 is cut off. As a result, the armature hub 24 becomes free with respect to the hub 23, so that the rotation of the shaft 4 is not transmitted to the pushing roller 20, and the front edge of the protrusion 29 and the stopper 27 are engaged, as shown in FIG. Extruding roller 2 at an angle
0 stops.

The above operation is the same in the case of feeding the second and subsequent sheets. The present invention, as schematically shown in FIG. 5, has a separation / feeding mechanism (which is known per se) having a structure for separating and feeding a sheet by a paper feed roller 31 and a fixed friction plate 32. It can also be applied to a device. That is, at the position shown in FIG.
A roller 33 similar to the above and a roller 34 corresponding to the push-out auxiliary roller 21 are provided, the rotational drive and stop angle of the roller 33 are controlled in the same manner as the push-out roller 20, and the leading end of the sheet immediately after separation is set to the roller 33. It is obvious that the same effect as that of the above-described embodiment can be achieved by squeezing it strongly with 34, 34 and pushing it out in the sheet feeding direction by a constant amount at the same speed as the sheet feeding roller 31.

Instead of the extrusion roller 20 (or 33) having a circular cross section, a member having a non-circular cross section (semi-circular cross section, oval cross section, etc.) can be used. Does not have to be specially provided. In addition, the push-out roller 2 is associated with the separation sheet feeding operation.
The means for controlling the operation of 0 (or 33 or the corresponding member) is not limited to that of the above embodiment.

[0023]

As is apparent from the above description, according to the present invention, the front end portion of the paper sheet separated by the combination of the paper feed roller and the separation roller or the friction plate is pinched in the paper feed direction. By having a pair of members for sending out a fixed amount at the same speed as the conveying speed by the paper feed roller and a means for driving at least one member of the pair of members, the feeding and conveying of the paper sheets are assisted. Therefore, it is possible to stabilize the paper feed start timing and the sheet conveyance state at the time of paper feed start. Therefore, by applying the present invention to a document feeder such as an image scanner or a facsimile or a paper feeder of a printer or a copying machine, it is possible to prevent the front end of a read image or a recorded image from being disturbed. is there.

[Brief description of drawings]

FIG. 1 is a schematic front view showing a configuration of a separating / feeding mechanism of a sheet feeding device and its periphery according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a push roller and an electromagnetic clutch of the apparatus of the embodiment.

FIG. 3 is a schematic side view for explaining a structure related to an extrusion roller of the apparatus of the embodiment.

FIG. 4 is an enlarged view of a portion related to an extrusion roller of the apparatus of the embodiment.

FIG. 5 is a schematic side view for explaining another embodiment of the present invention.

FIG. 6 is a schematic front view showing the configuration of a separation and feeding mechanism of a conventional paper feeding device.

FIG. 7 is a plan view of a paper feeding unit of the conventional apparatus.

FIG. 8 is a schematic side view for explaining the operation of the separation feeding mechanism of the conventional device.

[Explanation of symbols]

 1 Paper Feeding Roller 3 Separation Roller 8 Belt 11 Belt 14 Paper Leaf 20 Extrusion Roller 21 Extrusion Aid Roller 22 Electromagnetic Clutch 24 Armature Hub 27 Stopper 29 Protrusion 31 Paper Feed Roller 32 Friction Plate 33 Extrusion Roller 34 Extrusion Aid Roller

Claims (1)

[Claims] 1. A combination of a sheet feeding roller and a separating roller or a friction plate for separating the stacked sheets one by one and conveying them in the sheet feeding direction, and a front end portion of the sheets separated by this combination. And a means for driving at least one member of the pair of members for finding and pushing out the paper sheet in the paper feeding direction by a certain amount at the same speed as the conveyance speed by the paper feeding roller. Paper feeding device equipped.