JP2002173241A - Paper feeder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a paper feeder capable of preventing the soil of whole carbon paper sheets, when fed, with the track of a roller. SOLUTION: The paper feeder 1 comprises a pickup roller 9 for feeding stacked sheets S, a feed roller 11 for feeding the sheets S from the pickup roller 9 to a grip roller 14 at the downstream side, a reverse roller 13 having pressure contact with the feed roller 11 for returning the sheets S on and after the second one when transfer materials are multiple fed, and a sheet detecting sensor 7 for detecting the existence or not of the sheets S fed from the feed roller 11 to the grip roller 14. The pressure contact force of the reverse roller 13 with the feed roller 11 is changeable. If the carbon paper sheets are used as the sheets S, the pressure contact force of the reverse roller 13 is made smaller than that in using ordinary paper sheets as the sheets S.

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 in an image forming apparatus such as a copying machine, a printer, a facsimile, and the like.

[0002]

2. Description of the Related Art Generally, as shown in FIG. 3, a sheet feeder 100 used in an image forming apparatus such as a copying machine, a printer, a facsimile, etc., includes a roller pair of a feed roller 101 and a reverse roller 103 (see FIG. 3). FRR mechanism). The reverse roller 103 is supported by a shaft that is driven to rotate counterclockwise in the figure via a torque limiter, and is provided with an initial pressure by a pressure spring and an operating pressure obtained as a reaction force of the torque limiter torque, It is pressed against the feed roller.

The transfer material stacked on the paper feed tray 105 is
Feed roller 101 by pickup roller 107
The transfer material is fed to the image forming unit of the image forming apparatus main body by the rotation of the feed roller 101. on the other hand,
As shown in FIG. 4, when a plurality of transfer materials are overlapped and fed, the reverse roller 103 is rotated counterclockwise in the drawing by the action of the torque limiter to supply the second and subsequent sheets. By returning to the paper tray 105, double feeding of the transfer material is prevented.

Here, the condition for feeding one transfer material is as follows: the pressure contact force of the reverse roller 103 against the feed roller 101 is Pb, the operating pressure Pb, the friction coefficient between the feed roller 101 and the sheet is μr, and the torque limiter is When the return force is Ta, the condition for sending one transfer material is μr · P
b> Ta, and the friction coefficient between transfer materials is μp,
The condition for returning the second transfer material is Ta> μp · Pb. The paper feeder 100 using the FRR paper feed mechanism as described above.
In the above condition, the pressing force Pb of the reverse roller 103 must be a certain value as a condition for sending the transfer material.

[0005]

However, there is a need to use several spelled carbon papers as a transfer material. When such carbon paper is fed, the reverse roller 103 is connected to the feed roller as described above. Since the carbon paper is conveyed in a state of being pressed against 101, there is a problem that the pressing force forms a roller mark on the entire carbon paper.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a paper feeder capable of preventing roller marks from forming on the entire carbon paper even when carbon paper is fed.

[0007]

According to a first aspect of the present invention, there is provided a pickup roller for feeding a stacked transfer material, a feed roller for sending the transfer material from the pickup roller toward a downstream grip roller, and a feed roller. A reverse roller that comes into pressure contact with the roller and returns the second and subsequent transfer materials when the transfer material is double-fed; and a transfer material detection unit that detects the presence or absence of the transfer material sent from the feed roller toward the grip roller. In a paper feeding device capable of changing the pressure contact force of the reverse roller with respect to the feed roller, when carbon paper is used as the transfer material, the pressure contact force of the reverse roller is made smaller than when plain paper is used as the transfer material. It is characterized by the following.

According to the first aspect of the present invention, when carbon paper is used as the transfer material, the pressure of the reverse roller on the carbon paper is reduced by reducing the pressing force of the reverse roller against the feed roller. Is reduced, so that it is possible to prevent roller marks from being formed on the entire carbon paper. The detection of the carbon paper is performed, for example, by designating that the paper is carbon paper by operating the operation unit, or by selecting a paper feed tray for carbon paper.

According to a second aspect of the present invention, in the first aspect of the invention, when carbon paper is used as the transfer material, the number of sheets fed per hour is reduced as compared with the case where plain paper is used. Features.

[0010] According to the second aspect of the present invention, the first aspect is provided.
In addition to having the same effect as the invention described in the above, by reducing the reverse roller pressure contact force, even if the carbon paper passing between the feed roller and the reverse roller slips, even if the transport speed of the carbon paper is reduced, By reducing the number of sheets fed per time, the distance between the carbon papers is widened, so that the time for the carbon paper to reach the transfer material detection sensor and the time for removing the carbon paper can be sufficiently taken, thereby preventing the occurrence of a non-feed jam. be able to.

[0011] The invention according to claim 3 is the invention according to claim 1 or 2.
In the invention described in the above, when using carbon paper as the transfer material, it is necessary to reduce the pressing force of the reverse roller until the leading end of the carbon paper reaches the grip roller and the rear end of the carbon paper passes through the grip roller. Features.

According to the third aspect of the present invention, the first aspect is provided.
Or the same effect as that of the invention described in 2 above, and until the tip of the carbon paper reaches the grip roller, the pressing force of the reverse roller is, for example, the pressing force of plain paper, and the tip of the carbon paper is gripped. After reaching the roller, the pressure contact force of the reverse roller is changed to a pressure contact force smaller than that of plain paper. Therefore, it is possible to prevent a roller mark from being formed outside the range where the tip of the carbon paper hits the grip roller, and to increase the pressing force of the reverse roller until the tip of the carbon paper reaches the grip roller. Thereby, it is possible to prevent the carbon paper passing between the feed roller and the reverse roller from slipping, and to prevent occurrence of a non-feeding jam.

[0013]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a configuration diagram schematically showing a feeding device according to the present invention. The paper feeding device 1 is provided in a copying machine, has a paper feeding tray 3 for stacking sheets P, a paper feeding unit 5, and a sheet detection sensor 7. The sheet S is fed toward the printer. In this specification,
“Sheet” is used as a general name for sheets stacked on the paper feed tray 3 such as transfer paper (plain paper), OHP sheet, carbon paper, and the like.

The paper feed section 5 is a section for feeding the sheets S stacked on the paper feed tray 3 toward the space between the photoconductor 20 and the transfer device 22, and rotates the sheets S on the paper feed tray 3 by rotation. It has a pickup roller 9 for sending out, a feed roller 11, a reverse roller 13, and a grip roller 14, and constitutes a so-called FRR paper feed mechanism.

The feed roller 11 is located downstream of the pickup roller 9 in the transport direction (paper feed direction), and is driven to rotate by a driving force from a driving source (not shown). By this rotation, the feed roller 11 feeds the sheet S sent out by the pickup roller 9 toward the space between the photoconductor 20 and the transfer device 22 via the grip roller 14, the transport roller 31, and the registration roller 33. . Below the feed roller 11, a reverse roller 13 that is in pressure contact with the feed roller 11 is disposed.

The reverse roller 13 is always rotationally driven in the direction of returning the sheet S to the sheet feeding tray 3 (reversely driven), and when the sheet S sent out by the pickup roller 9 is double-fed. Then, the multi-fed sheets S are separated one by one. This utilizes the function of a torque limiter (not shown) built in the reverse roller 13. When the torque transmitted to the reverse roller 13 is large, that is, when only one sheet S is being fed, the reverse roller 13 rotates following the feed roller 11 by the action of the torque limiter, and rotates together with the feed roller 11. Feed.

On the other hand, when the torque of the torque limiter is small, that is, when two or more sheets S are fed between the feed roller 11 and the reverse roller 13, the reverse roller 13 is driven to rotate in the reverse direction and the second and subsequent sheets are driven. Is returned to the paper feed tray 3 (separated sheets S are separated).

In this embodiment, as shown in FIG. 2, the pressing force of the reverse roller 13 against the feed roller 11 can be changed (switchable) by the solenoid 15. When the solenoid 15 is ON, the reverse roller 13 is located at the position indicated by the two-dot chain line due to the suction of the solenoid 15 and is in pressure contact with the feed roller 11 at a predetermined pressure in the area surrounded by the one-dot chain line in FIG. When the solenoid 15 is turned off, the reverse roller 13 moves toward the position indicated by the solid line, and the pressing force of the reverse roller 13 is reduced. The dashed line in FIG. 2 encloses the pickup roller 9 and the feed roller 1.
This is for describing the operation of the reverse roller 13 with respect to 1.

The sheet detection sensor 7 includes the feed roller 1
1 and between the reverse roller 13 and the grip roller 14, and in the vicinity of the grip roller 14,
The sheet S fed by the feed roller 11 is detected. In the present embodiment, the sheet detection sensor 7 is disposed below the sheet S toward the grip roller 14, but may be disposed above the sheet S, and may be disposed near the grip roller 14. It should be done.

Next, the operation of the present embodiment will be described based on the above configuration. When plain paper is used as the sheet S, the reverse roller 13 is pressed against the feed roller 11 with a predetermined pressing force by turning on the solenoid 15. The sheet S sent from the sheet feed tray 3 by the pickup roller 9 is sandwiched between the feed roller 11 and the reverse roller 13,
The conveyance roller 31, the registration roller 3
3, the paper is fed between the photoconductor 20 and the transfer device 22.

On the other hand, when carbon paper is used as the sheet S, the solenoid 15 is turned off, and the pressing force of the reverse roller 13 against the feed roller 11 is reduced as compared with the case where plain paper is used. The carbon paper fed by the rollers 9 is fed between the photoconductor 20 and the transfer device 22. The detection of the carbon paper is performed by operating the operation unit to specify that the paper is carbon paper, or by selecting a paper feed tray dedicated to carbon paper.

As described above, when the carbon paper is used, the pressure of the reverse roller 13 on the carbon paper is reduced by reducing the pressing force of the reverse roller 13 against the feed roller 11, so that the entire carbon paper is Roller marks can be prevented from being formed.

In this embodiment, when carbon paper is used, the timing of image formation is changed so as to reduce the productivity of the entire apparatus. That is, the control unit reduces the number of sheets of carbon paper fed from the sheet feed tray 3 by the pickup roller 9 per time as compared with the case where plain paper is used, thereby widening the interval between the carbon papers. are doing.

Therefore, by reducing the pressing force of the reverse roller 13, even if the feed roller 11 and the carbon paper slip and the transport speed of the carbon paper is reduced, the distance between the carbon papers is increased. The time to reach the transfer material detection sensor and the time to leave the transfer material detection sensor can be sufficiently taken, and the occurrence of a non-feeding jam can be prevented.

Next, another embodiment will be described. In the description, the same parts as those described above are denoted by the same reference numerals, and description thereof will be omitted.

In the second embodiment, when carbon paper is used as the sheet S, the detection of the front end of the carbon paper by the sheet detection sensor 7 is performed until the front end of the carbon paper reaches the grip roller 14. Before turning on, the solenoid 15 is turned on and the reverse roller 13 is turned on.
The carbon paper is fed out while keeping the pressing force of the paper in the state of feeding plain paper. The solenoid 15 is turned on between the time when the leading end of the carbon paper reaches the grip roller 14 and the time when the rear end of the carbon paper passes through the grip roller.
F, the pressing force of the reverse roller 13 is reduced.

As described above, after the leading end of the carbon paper reaches the grip roller 14, the pressing contact force of the reverse roller 13 is set to be smaller than that of the plain paper, so that the leading end of the carbon paper contacts the grip roller 14. Roller marks can be prevented from sticking out of the range up to this point. Until the leading end of the carbon paper reaches the grip roller 14, the pressing force of the reverse roller 13 is the same as the pressing force of plain paper, so that the carbon paper passing between the feed roller 11 and the reverse roller 13 is used. Can be prevented from slipping, and the occurrence of non-feeding jam can be prevented.

The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention. For example, in the present embodiment, the sheet feeding device 1
Is provided in a copying machine, but the present invention is not limited to this. Even when provided in an image forming apparatus such as a printer, a facsimile, or a multifunction peripheral thereof, the same operation and effect can be obtained.

[0029]

According to the first aspect of the present invention, when carbon paper is used as the transfer material, the pressing force of the reverse roller against the feed roller is reduced to reduce the reverse roller applied to the carbon paper. Since the pressure is reduced, it is possible to prevent roller marks from forming on the entire carbon paper.

According to the second aspect of the invention, the same effect as that of the first aspect of the invention is obtained, and the carbon paper passing between the feed roller and the reverse roller is reduced by reducing the reverse roller pressing force. Even if the paper slips and the conveyance speed of the carbon paper becomes slow, the time between the carbon papers reaches the transfer material detection sensor and the time required for the carbon paper to escape is reduced by reducing the number of sheets fed per hour, thereby widening the space between the carbon papers. And the occurrence of a non-feeding jam can be prevented.

According to the third aspect of the present invention, the same effect as that of the first or second aspect is obtained, and the pressing force of the reverse roller is normally reduced after the leading end of the carbon paper reaches the grip roller. Since the pressing force is changed to a smaller pressure than that of paper, it is possible to prevent roller marks from being formed outside the range where the tip of the carbon paper is applied to the grip roller, and until the tip of the carbon paper reaches the grip roller. By increasing the pressing force of the reverse roller, it is possible to prevent the carbon paper passing between the feed roller and the reverse roller from slipping, and to prevent occurrence of non-feeding jam.

[Brief description of the drawings]

FIG. 1 is a configuration diagram schematically showing a sheet feeding device to which the present invention is applied.

FIG. 2 is an enlarged perspective view showing the vicinity of a reverse roller.

FIG. 3 is an enlarged sectional view showing the vicinity of a conventional reverse roller.

FIG. 4 is a cross-sectional view illustrating a state in which transfer paper is multi-fed between a feed roller and a reverse roller according to the related art.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 sheet feeder 7 sheet detection sensor (transfer material detection means) 9 pickup roller 11 feed roller 13 reverse roller 14 grip roller S sheet (transfer material)

Claims (3)

[Claims] A pickup roller for sending out the loaded transfer material, a feed roller for sending out the transfer material from the pickup roller to a downstream grip roller,
A reverse roller that presses against the feed roller and returns the second and subsequent transfer materials when the transfer material is double-fed; a transfer material detection unit that detects the presence or absence of the transfer material sent from the feed roller toward the grip roller; In a paper feeder that can change the pressing force of the reverse roller against the feed roller, when using carbon paper as the transfer material, the pressing force of the reverse roller is smaller than when using plain paper as the transfer material. A sheet feeding device characterized in that: 2. The sheet feeding device according to claim 1, wherein the number of sheets fed per hour is smaller when carbon paper is used as the transfer material than when plain paper is used. 3. When carbon paper is used as the transfer material, the pressing force of the reverse roller is reduced until the leading end of the carbon paper reaches the grip roller and the rear end of the carbon paper passes through the grip roller. The sheet feeding device according to claim 1 or 2, wherein