JPH07187428A - Reverse roller type separation device - Google Patents

Abstract

PURPOSE:To apply pressure force to a paper only when a reverse roller reverses, that is only when the paper is returned without applying excess load on the paper at all times by a pickup roller etc., in order to prevent the returned paper being returned excessively by a reverse roller forming a separation roller when the papers are fed in two sheets. CONSTITUTION:A reverse roller type separation device has a separation roller comprising a pickup roller 3 for taking out a paper 6 on a paper feed base 5 at a top part and a first pressure plate 13 for pressing the pickup roller from upward and a feed roller 1 for nipping the paper in order to separate the paper taken out by the pickup roller and a reverse roller 2. Excess return of the paper returned by the reverse of the reverse roller is prevented by disposing one or more second pressure plate 14 different from the first pressure plate and pressing the paper.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a separating device for preventing double feeding in a paper feeding device using a friction reverse roller (FRR), and more particularly, to a paper feeding device separated by a reverse roller in a direction opposite to the paper feeding direction. The present invention relates to a reverse roller type separating device capable of preventing excessive returning of returned paper.

[0002]

2. Description of the Related Art An image forming apparatus such as a copying machine, a printer, and a facsimile apparatus is provided with a paper feeding device for feeding a document to a reading section and a recording sheet to an image forming section. A plurality of originals and recording papers are stacked in the originals and recording papers setting section, and are picked up one by one by the pickup roller and fed to the reading section and the image forming section. In many cases, a pair of separating rollers is arranged downstream of the pickup roller to prevent double feeding of documents and recording sheets. The pair of separating rollers is composed of a feed roller that is driven to rotate in the sheet feeding direction and a reverse roller that is driven to rotate in the returning direction opposite to the sheet feeding direction with a weak torque via a torque limiter. Nip on the outer peripheral surface. When there is no paper in the nip and when one sheet of paper normally enters the nip, the reverse roller is rotated by the feed roller or through the paper in the paper feeding direction. When more than one sheet of paper enters the nip portion at the same time, the frictional resistance of the contact surface between the sheets in the double feed state causes the sheets of paper to slip and the reverse roller is transmitted through the torque limiter. It becomes possible to rotate in the opposite direction by the torque in the opposite direction, and this reverse rotation causes the paper on the reversing roller side to return in the opposite direction.

FIG. 4 is a schematic structural explanatory view of a copying machine equipped with an automatic document feeder (ADF) using the friction reverse roller (FRR) system.
(b) is an explanatory view of the operation of the separation roller pair. The ADF includes a pickup roller 3 that feeds the originals 6 stacked on the original tray 5 one by one, and a pickup roller 3
A pressure plate 4 which is located above and pushes down the document, separation rollers (feed roller 1, reverse roller 2) positioned downstream of these, a registration roller pair 7, a pressing roller 8, a conveyance belt 9, It has a contact glass 10, a document stopper 11, and a reversal paper ejection unit 12.

The reverse roller 2 is provided with a torque limiter (not shown), and when there is no paper in the nip portion between the feed roller 1 and the reverse roller 2 and when there is one paper, the reverse roller 2 is in the paper feeding direction A. Although it rotates, when a plurality of sheets enter between the nips, the reverse roller reverses the sheet feeding direction and reverses until the number of sheets between the nip portions becomes one. At this time, the sheets other than the lowermost sheet are returned to the document tray 5 side B. At this time, the sheet returned by the separation roller 2 is returned with the linear velocity of the reverse roller as the initial velocity.
It may be returned too much and jump out from the document tray 5.

Conventionally, in order to solve such a problem,
Although the recording paper on the original tray is constantly pressed between the pickup roller 3 and the pressure plate 4 to prevent excessive return, this method reduces the pressure applied by the pickup roller and the pressure plate. Since it becomes necessary to make the size larger than necessary for feeding, a large load is constantly applied to the pickup roller, and the load on the paper is also large when there is one sheet between the nips, which may damage the paper. Cause

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above, and in order to prevent the paper returned by the reverse roller constituting the separating roller from being excessively returned when a double feed occurs, the pickup roller is always used. An object of the present invention is to provide a reverse roller type separating device that applies a large pressing force to a sheet only when the reverse roller reversely rotates, that is, only when the sheet is returned, without applying an excessive load to the sheet. .

[0007]

In order to achieve the above object, the present invention provides a pickup roller for taking out a sheet on a sheet feeding table from the lowermost portion, and a first roller for pressing the pickup roller from above.
And a separating roller including a feed roller and a reverse roller for nipping the sheet taken out by the pickup roller, the sheet feeding and separating device being separated from the first pressing plate. One or more second pressure plates are arranged in the above position to prevent excessive return of the sheet returned by the reverse rotation of the reverse roller by pressing the sheet, and the second pressure plate is vertically moved. Rotatably and pivotally, and when the reverse roller rotates in the paper feeding direction, a second spring is used to separate the tip pressing portion of the second pressure plate from the paper.
While the pressure plate is pulled up, an electromagnet for attracting the second pressure plate against the spring is provided so that the tip pressing portion is brought into pressure contact with the upper surface of the sheet by the attraction force of the electromagnet. The electromagnet is turned on and off according to the switching of the reverse roller rotation direction.
And a switch for turning on the switch when the reverse roller reversely rotates in the return direction to excite the electromagnet,
It is characterized in that the tip pressing portion is configured to be in pressure contact with the upper surface of the sheet.

Hereinafter, the present invention will be described in detail with reference to the preferred embodiments shown in the accompanying drawings. FIG. 1 is a front cross-sectional view showing the configuration of the main part of a separation device to which the present invention is applied.
Is a feed roller driven in the sheet feeding direction, 2 is a reverse roller driven in the returning direction with a weak torque through a torque limiter, and 3 is in contact with the lower surface of the document 6 on the document tray (sheet feeding table) 5. A pickup roller for picking out the lowermost original, 5 is an original tray for stacking originals 6, 13 is a first pressing plate for pressing down and pressing the upper surface of the original at a position directly above the pickup roller 3, and 14 is a first pressing plate 13. It is a second pressure plate pivotally supported on the upstream side so as to be vertically rotatable. The first pressure plate 13 has its upper end supported by the main body C of the apparatus and presses the upper surface of the document at its lower end, as in the conventional case, to the extent that the minimum necessary frictional force for feeding by the pickup roller 3 is secured. The pressure is set to.

The second pressure plate 14 is pivotally supported at its intermediate portion by a shaft 18 provided at an appropriate position on the inner wall of the main body of the apparatus so as to be vertically rotatable, and when the reverse roller 2 is normally rotated (feed roller, etc.). (Turning with = rotation in the paper feed direction)
The spring 17 is configured so that its tip pressing portion 14a is pulled upward. Further, a magnetic material sheet (magnetic member) 16 made of a magnetic material such as iron is fixed to the upper surface of the other end of the second pressure plate 14, and the electromagnet 15 is provided on the ceiling surface of the device body facing the iron sheet 16. Is fixed. When the reverse roller 2 is rotated in the reverse direction, a current flows through the electromagnet 15. When the electromagnet is excited by energization, the iron sheet 16 is attracted and the second pressure plate 14 is rotated by the shaft 18. By rotating in a counterclockwise direction about the
4a presses the document 6 above. In other words, according to this embodiment, while the normal sheet-by-sheet sheet feeding is being performed, the reverse roller 2 is normally rotated in the sheet feeding direction, so that the electromagnet 15 is not energized and a suction force is generated. However, since the electromagnet 15 generates an attractive force and shifts the second pressure plate 14 to the pressed state only when the reverse roller 2 reversely rotates due to the occurrence of double feeding, it is caused by an excessive force during non-double feeding. Eliminates the need for pressurization.

3 (a), (b) and (c) show that the electromagnet is turned on by interlocking with the switching of the reverse roller between normal rotation and reverse rotation.
2 is a schematic diagram showing a configuration example for turning on and off F, a reverse roller 2 via a torque limiter 19 at an end of a drive shaft 2a driven by a weak torque in a reverse direction by a driving force from a drive source (not shown). It is fixed. A conductive rod (terminal) 20 is projected from the end surface of the torque limiter 19 in parallel with the drive shaft 2a, and a table 22 is arranged in the movement path of the conductive rod 20 which is rotated by the rotation of the torque limiter 19. At the same time, positive and negative electrodes 21a and 21b are provided on the surface of the table 22 in a protruding manner. The torque limiter 19 is, as is well known, an inner member integrated with the drive shaft 2a, an outer member located on the outer diameter side of the inner member and integrated with the reverse roller 2, and a coil spring of a predetermined pressure interposed therebetween. These coil springs and the like allow the reverse roller 2 to rotate in the same direction when the reverse roller 2 rotates in the same direction by the forward rotation of the feed roller 1 in the paper feeding direction. Therefore, when the drive torque from the feed roller 1 is not transmitted to the reverse roller 2, the drive shaft 2a allows the reverse roller 2 to reversely rotate. Since the conductive rod 20 is integrated with the reverse roller via the outer member that constitutes the torque limiter 19, when the reverse roller 2 rotates in the forward direction, it hits the table 22 at the position shown by the solid line in FIG. 3 (b). The table 22 comes into contact with the table 22 and stops, and the table 22 comes into contact with the table 22 at the position shown by the dotted line during reverse rotation and stops.

The electrodes 21a and 21b are respectively connected to the plus and minus terminals of the power source 23 as shown in FIG. 3 (c), and the electromagnet 15 is connected by the conductive rod 20 contacting the electrodes 21a and 21b. Excited, the second pressure plate 14
The upper end of the above is sucked and the tip pressing portion 14a is lowered. The electrodes 21a and 21b and the conductive rod 20 constitute a switch for turning on and off the electromagnet. As a result, without complicating the configuration, the second pressure plate can be pressed in conjunction with the reverse rotation of the reverse roller, and the pressure can be released when the reverse roller rotates in the forward direction.

Next, in the above embodiment, the first pressure plate 13
The second pressure plate 14 is arranged on the upstream side of the
4 is configured to press the document independently of the pickup roller 3. In this case, the pickup roller 3 is conveying the lower original even while the reverse roller 2 is rotating in the reverse direction and the second pressure plate 14 is pressing the original. The pressing force applied to hinders the conveying force of the pickup roller 3. In order to eliminate such a problem, the second pressure plate 14 is replaced with the first pressure plate 1.
It is effective to dispose the second pressure plate 14 at a position in parallel with the third pressure plate 3, that is, at a position directly above the pickup roller 3 avoiding the first pressure plate 13 where the pressure is set relatively weak. . That is, with this structure, the pressure applied by the second pressure plate 14 is applied to the pickup roller 3 via the document, so that the second pressure plate 14 prevents the document from returning too much and picks it up. The function of increasing the carrying power of the roller 3 is exhibited. In the above embodiment, the separating device in the device for feeding the original document is illustrated, but the present invention is also applicable to the separating device used for the recording paper feeding device.

[0013]

As described above, according to the present invention, in addition to the first pressure plate that constantly applies pressure to the pickup roller, the second pressure plate that applies pressure only when the reverse roller rotates in reverse is arranged. Therefore, in order to prevent the paper from being excessively returned due to the reverse rotation of the reverse roller, it is not necessary to constantly set a strong pressure between the pickup roller and the pressure plate.
It is possible to reduce the load on the paper when there is one sheet in the nip portion and the load applied to the pickup roller.

Further, by using the electromagnet as the pressing means for the second pressing plate, the load applied to each part can be reduced without complicating the structure. Also, turn on the electromagnet,
By providing a switch to turn off on the reverse roller side, it becomes easier to accurately detect the reverse rotation of the reverse roller,
The pressing force of the second pressure plate is set to O according to the movement of the separation roller.
It is possible to turn off N and OFF. Further, by arranging the second pressure plate directly above the pickup roller, it is possible to prevent the selective pressing force of the second pressure plate from hindering the carrying force.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a main part configuration of a separation device of the present invention.

2 (a) and 2 (b) are explanatory views of a main part configuration of the separation device.

3A, 3B, and 3C are diagrams showing a schematic configuration of an example of a switch provided on a reverse roller.

FIG. 4 is a schematic configuration explanatory view of an image forming apparatus including a conventional paper feeding / separating device.

5A and 5B are configuration diagrams and operation explanatory diagrams of an FRR method when a single sheet is conveyed and when double-fed sheets are conveyed.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 feed roller, 2 reverse roller, 2a drive shaft, 3 pickup roller, 4 pressure plate, 5 document tray, 6 document, 13 pickup roller, 14 second pressure plate, 15 electromagnet, 16 iron sheet (magnetic member), 17 Spring, 18 axis, 19 torque limiter, 2
0 conductive rod, 21a, 21b electrodes, 22 table,

Claims (3)

[Claims] 1. A pickup roller for taking out a sheet on a sheet feeding table from the lowermost part, a first pressure plate for pressing the pickup roller from above, and a sheet for separating the sheet taken out by the pickup roller. In a paper feeding / separating apparatus including a feed roller for nipping the sheet and a separation roller including a reverse roller, one or more second pressure plates are arranged separately from the first pressure plate to press the sheet. Therefore, the reverse roller type separating device is configured to prevent excessive return of the sheet returned by the reverse rotation of the reverse roller. 2. The second pressure plate is rotatably supported in a vertical direction, and a tip end pressing portion of the second pressure plate is pressed by a spring when the reverse roller rotates in the sheet feeding direction. While the second pressure plate is pulled up so as to be separated from the top, an electromagnet that attracts the second pressure plate against the spring is provided, so that the tip pressing portion is moved by the attraction force of the electromagnet. The reverse roller type separating device according to claim 1, wherein the reverse roller type separating device is configured to be pressed against the upper surface of the sheet. 3. A switch for turning on and off the electromagnet in response to switching of the rotation direction of the reverse roller is provided, and the switch is turned on when the reverse roller reversely rotates in the returning direction to excite the electromagnet, 3. The reverse roller type separating device according to claim 2, wherein the tip pressing portion is configured to be in pressure contact with the upper surface of the sheet.