JPH11199075A - Paper feeder - Google Patents

Abstract

(57) [Summary] (with correction) [Problem] To reduce the load torque of the separation feeding section of the feeding stage not used at the time of feeding, a large amount of time is required when separating the separation roller from the feeding roller. Effective and reliable prevention of paper feeding from unused paper feed trays without modification and cost. A paper feeder of a friction separation roller type, comprising press-contact means (6, 7) for pressing a separate roller (3) against a feed roller (1), and a release mechanism (10) for releasing press-contact by the press-contact means. In the above, when the pressure on the separate roller is released, the separate roller stops at the retreat position separated from the feed roller, and at the retreat position, a part of the outer peripheral surface of the separate roller is in a state of protruding a small amount into the paper transport path. .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copying machine, a printer,
The present invention relates to an improvement of a sheet feeding device used for an image forming apparatus such as a facsimile apparatus and a printing apparatus, and in particular, suppresses paper feeding from an unused sheet feeding stage at low cost in a multi-stage sheet feeding device having a plurality of sheet feeding stages. The present invention relates to a sheet feeding device capable of doing this.

[0002]

2. Description of the Related Art In an image forming apparatus having a plurality of paper feed stages, sheets of different types such as sizes are set in paper feed trays provided in the respective paper feed stages, so that an arbitrary type of paper is provided. To form an image. In each paper feed stage,
Each is provided with a call roller for taking out the sheet on the tray and a separating / feeding unit for separating the taken out sheet, and these rollers and the separating / feeding unit are individually driven. In such a multi-stage paper feeder, the drive of the call roller and the separation / feed unit provided in each paper feed stage is realized by one motor for cost reasons. For this reason, a considerable load is applied to this motor, and in order to reduce the load, it is necessary to reduce the load torque of the driven member provided in each paper feed stage. For example, in a paper feeder of a FRR paper feed system (friction separation roller system), a nip between a feed roller and a reverse roller (separate roller) of a paper feed stage not used as a load reduction measure is released. Is adopted. That is, as is well known, the FRR sheet feeding system feeds the separation feeding unit with a feed roller rotating in the feeding direction, and presses against the feed roller with a small torque in a direction opposite to the feeding direction. When the double-fed paper enters between the rollers, the paper on the side in contact with the feed roller is sent out in the feeding direction, while the paper on the reverse roller side is conveyed in the returning direction. By doing so, double feed is prevented. In this paper feeding system, when paper is fed from one paper feeding stage, the transmission of the driving force to the separation feeding unit of the other unused paper feeding stage is provided on each feed roller shaft. Although the feed roller is disengaged by the feed clutch (electromagnetic clutch), the reverse roller of the unused sheet feed stage is always rotating in the return direction, so that the load increases if the reverse roller is pressed against the feed roller and rotates together. . For this reason, by separating both rollers as described above, it is possible to reduce the load torque of the unused sheet feeding stage.

[0003] According to this method, the total load torque in the separation feeding section provided in each paper feed stage is greatly reduced, whereby the transmission of the driving force to each feed roller shaft is turned on and off.
When the paper is in contact with the feed roller, the paper is fed by the feed roller even though the paper feed stage is not used, because the feed clutch that performs FF causes the feed clutch to rotate and rotate the feed roller. There was a problem that a jam occurred when sent. That is, a feed clutch as an electromagnetic clutch is composed of an input-side clutch piece and an output-side clutch piece. The input-side clutch piece always rotates, including when the clutch is off, and the output-side clutch piece only rotates when the clutch is on. The output is transmitted to the feed roller shaft by engaging with the input side clutch piece. However, when the reverse roller is separated from the feed roller and the load on the feed roller is reduced to zero, the output clutch piece connected to the feed roller shaft becomes unloaded, and is rotated by the input clutch piece. This causes a situation in which the feed roller of the paper feed stage that is not rotated rotates. Conventionally, ball bearings have been added to the feed clutch to reduce frictional resistance between the two clutch pieces to prevent entrainment, and to reduce sliding friction in the clutch. Costly solutions such as coating with materials have been adopted.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above, and is directed to a multi-stage paper feeder, in which a separate feeder comprising a feed roller and a separate roller is provided at each paper feed stage. In order to reduce the load torque of the separation feeding unit of the paper feed stage that is not used when feeding paper, the separation roller is separated from the feed roller. It is another object of the present invention to provide a sheet feeding device capable of effectively and surely preventing sheet feeding from an unused sheet feeding stage.

[0005]

In order to achieve the above object, the present invention is directed to a feed roller rotating in a sheet feeding direction, a pair of pressure rollers pressed against the feed roller, and a pair of feed rollers via a torque limiter. A frictional separation roller type sheet feeding device having a separation feeding section including a separation roller to which a driving force is always applied in a reverse direction, and a pressing means for pressing the separation roller against the feed roller; In the sheet feeding device provided with a release mechanism for releasing the pressure contact by the means, when the pressure on the separate roller is released, the separate roller stops at the retracted position separated from the feed roller, and at the same time, the outer peripheral surface of the separate roller is in the retracted position. The unit is in a state of projecting a minute amount into the paper transport path. The invention according to claim 2 comprises a feed roller which rotates in the sheet feeding direction, and a separate roller which is pressed against the feed roller to form a pair and to which a driving force is always applied in the opposite direction via a torque limiter. A friction separation roller type paper feeder having a separation feeding unit, wherein the paper feeder includes a pressing unit for pressing the separate roller against the feed roller, and a release mechanism for releasing the pressing by the pressing unit.
An auxiliary guide that can move up and down is provided on the upstream side of the separation feeding section,
When the separate roller is separated from the feed roller, the auxiliary guide presses the paper passing through the transport path in a direction away from the outer peripheral surface of the feed roller by its tip, and the separate roller presses against the feed roller. The sheet is retracted by a sheet passing when the sheet is in a state of being allowed to pass the sheet.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the accompanying drawings. 1 (a) and 1 (b) are a perspective view and an end view showing the configuration of a main part (separation and feeding unit) of a friction separation roller type sheet feeding device according to an embodiment of the present invention. The separation feeding unit includes a feed roller 1 that rotates in a sheet feeding direction indicated by an arrow A, and a feed roller 1 that is located below the feed roller 1 and is in pressure contact with the feed roller and in the opposite direction via a torque limiter 2. A separate roller 3 to which a constant driving force is applied, a separate roller shaft 4 for fixedly supporting the axis of the separate roller 3, and a roller-shaped pressure-side bearing 5 coaxially supported at the tip of the separate roller shaft 4. A pressure lever 6, a spring 7 for urging the pressure lever 6 in a direction of pressing the pressure lever 6 against the pressure-side bearing 5, and a fulcrum-side bearing 8 for pivotally supporting the other end of the separate roller shaft 4 to the side plate 9. A release lever 10 for urging the pressure lever 6 in a direction opposite to the pressure, and a guide plate 11 for guiding the paper on the upper surface.
And a feed clutch (electromagnetic clutch) 12 provided at the other end of the shaft 1a of the feed roller 1 to turn ON / OFF the transmission of the driving force. The separate roller shaft 4 is supported by two bearings 5 and 8, of which the pressure-side bearing 5 is supported by a pressure lever 6 and urged toward the feed roller 1 by a spring 7, whereby the separate roller 5 is rotated. 3 is pressed against the feed roller. On the other hand, the fulcrum-side bearing 8 is supported by a side plate 9. The pressing operation by the pressing means including the spring 7 and the pressing lever 6 is performed by driving the releasing lever 10 in a counterclockwise direction by a driving mechanism (not shown).
Is rotated clockwise to retract the separate roller 3 in the direction (downward) opposite to the pressing direction. The spring 7 and the pressure lever 6 constitute a pressing means, and the drive mechanism and the release lever 10 constitute a release mechanism.

A characteristic configuration of the present invention is that, in the separating and feeding section having the above configuration, when the separate roller 3 is located at the retracted position shown by the solid line, the outer peripheral surface of the separate roller 3 is moved along the sheet transport path, that is, Instead of being completely retracted from the upper surface of the guide plate 11, a part of the outer peripheral surface is configured to slightly protrude above the upper surface of the guide plate 11. While the paper is being fed in another paper feed stage, only the separation roller of the unused paper feed stage is constantly rotating in the direction opposite to the feeding direction (return direction). For this reason, for example, since the uppermost sheet jumps out of the stacked sheets P and remains in the nip after the preceding job in the sheet feeding stage is completed, the sheet P on the tray comes into contact with the feed roller 1 in the unused sheet feeding stage. In this case, even if the paper P is moved by the minute rotation of the feed roller 1 caused by the rotation of the feed clutch 12, the paper P is returned by contacting the separate roller 3 partially projecting into the transport path. Returned (prevented from moving forward). That is, paper feeding from the unused paper feed stage is prevented, and the load torque in the unused paper feed stage can be effectively reduced.

FIGS. 2 (a) and 2 (b) are explanatory diagrams of the main parts of another embodiment of the present invention. The constitution of the separation / feeding section shown in FIG. 1 (a) is also referred to. explain. In the separation feeding section of this embodiment, the auxiliary guide 13 is disposed upstream of the separation feeding section in FIG. 1 so that the leading end of the sheet P protruding from the tray side is forcibly separated from the feed roller 1. To push it down. This auxiliary guide 13 is a fulcrum 1
It is supported rotatably in the vertical direction about 4
The leading end 13a is lowered into the transport path by its own weight,
By locking the rear end by the stopper 15,
The lowering position of the tip is regulated. The lowermost position regulated in this way is set to be lower than the lowermost surface of the feed roller 1. As a result, even if the uppermost sheet jumps out of the stacked sheets P after the preceding job and remains in the nip portion, the sheet pressed down by the weight of the auxiliary guide 13 does not come into contact with the feed roller, and the feed roller pulls the sheet. The paper does not advance even if it rotates. In the case where the separation and feeding section of the sheet feeding stage in the state of FIG. 2A is used for sheet feeding, when the topmost sheet is fed by a call roller (not shown), the sheet is pushed by the sheet to be assisted. Since the guide 13 is retracted upward, the sheet directly reaches the nip portion of the separation unit and is transported. Accordingly, the weight of the auxiliary guide 13 and the weight balance between the front end and the rear end of the fulcrum 14, the auxiliary guide 1 in which the fulcrum 14 and the fulcrum are fitted.
Of course, the above operation can be performed by properly setting the state of the loose fit with the hole 3.

[0009]

As described above, according to the present invention, there is provided a sheet feeding apparatus which is a multi-stage type sheet feeding apparatus, wherein each sheet feeding stage is provided with a separation feeding section comprising a feed roller and a separate roller. In order to reduce the load torque of the separation feeding section of the paper feed stage that is not used during paper feeding, when the separation roller is separated from the feed roller, it is not necessary to make significant modifications and increase the cost of unused paper feeding. It is possible to provide a sheet feeding device capable of preventing the sheet from being sent out from the step. That is,
In the first embodiment, when the separate roller is separated from the feed roller, the separate roller is not completely retracted from the paper transport path, but is retracted to such an extent that a part remains in the transport path. The sheet whose leading end protrudes from the nip portion of the roller is prevented from advancing by contacting the separate roller. In other words, by simply improving the release amount of the separate roller, it is possible to suppress the feeding of the sheet from the unused sheet feeding stage without increasing the cost. In addition, in the second embodiment, the sheet protruding from the nip portion is pressed in the direction of retreating from the feed roller by adding an auxiliary guide, so that when the separate roller is in the retreat state, the sheet is advanced. Can be eliminated. That is, it is possible to reliably prevent the paper from being fed from the unused paper feed stage without increasing the cost by a simple improvement simply by adding the auxiliary guide.

[Brief description of the drawings]

FIGS. 1 (a) and 1 (b) are a perspective view and an end view showing a configuration of a main part (separation and feeding unit) of a friction separation roller type sheet feeding device according to an embodiment of the present invention.

FIGS. 2 (a) and (b) are explanatory diagrams of a main part configuration of another embodiment of the present invention.

[Explanation of symbols]

1 feed roller, 2 torque limiter, 3 separate roller, 4 separate roller, 5 pressure side bearing,
6 pressure lever, 7 spring, 8 fulcrum bearing, 9
Side plate, 10 release lever, 11 guide plate, 12 feed clutch, 13 auxiliary guide, 14 fulcrum, 15
Stopper.

Claims (2)

[Claims] A feed roller which rotates in a sheet feeding direction and a separate roller which is pressed against the feed roller to form a pair and to which a driving force is always applied in a reverse direction via a torque limiter. A friction separation roller type paper feeder having a feeding portion, comprising: a pressure contact means for pressing the separate roller against the feed roller; and a release mechanism for releasing the pressure contact by the pressure contact means. At the time of release, the separate roller moves to the retreat position separated from the feed roller, and at the same time, at the retreat position, a part of the outer peripheral surface of the separate roller protrudes into the paper transport path by a small amount. Paper equipment. 2. A separating and feeding apparatus comprising: a feed roller rotating in a sheet feeding direction; and a separate roller which is pressed against the feed roller to form a pair and to which a driving force is always applied in a reverse direction via a torque limiter. A friction-feeding roller-type paper feeder having a feeding unit, comprising: a pressing unit for pressing the separate roller against the feed roller; and a release mechanism for releasing the pressing by the pressing unit. An auxiliary guide that can move up and down is provided on the upstream side of the feed roller. When the separate roller is separated from the feed roller, the auxiliary guide separates the sheet passing through the transport path from the outer peripheral surface of the feed roller by its tip. Direction, and is retracted by the paper passing when the separate roller is pressed against the feed roller to allow the paper to pass. A sheet feeding device, characterized in that: