JP2003206044A - Sheet feeder, sheet feeding method, and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To securely prevent the occurrence of feeding failure by changing the separating pressure for the paper feeding operation again and improving the feeding force of a separating means to cope with a thick sheet and a sheet with high stiffness when the wrong feeding is generated in the sheet feeding operation. <P>SOLUTION: A separating roller 9 abutting on a paper feeding roller 5 is supported by a support plate 11 through a torque limiter 10, and a presser member 13 is held by the support plate 11 at the bottom surface thereof through a compression spring 12. The presser member 13 abuts on an inclined surface of a slide member 14 to be displaced in the horizontal direction by turning on/off a separating solenoid 15. When a feeding failure is caused, a control unit 2 turns the separating solenoid 15 on with the driving data, and makes the abutting member 13 abut on the inclined surface of the slide member 14 at a high position, and the energizing force of the compressed compression spring 12 applying to the separating roller 9 is increased, and the separating pressure is raised to increase the paper sheets feeding force, and the paper sheets can be securely fed. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is provided in a part of a main body apparatus such as an image forming apparatus having an image forming section as a sheet processing section, and separates sheets stored in a storage means one by one. The present invention relates to a sheet feeding device that feeds a sheet to a sheet processing unit, a sheet feeding method, and an image forming apparatus including the sheet feeding device.

[0002]

2. Description of the Related Art A sheet processing apparatus, such as an image forming apparatus such as a printer, a facsimile, and a copying machine, which performs a predetermined process such as an image forming process on a sheet in a sheet processing unit such as an image forming unit, has a storage means. A sheet feeding device that feeds the sheets stored in the sheet processing unit to the sheet processing unit one by one is provided. Generally, a sheet feeding device is configured to apply a pressing force to a sheet fed from a storage means such as a sheet cassette in a thickness direction of the sheet via a feeding means such as a roller or a belt. The sheets are separated one by one and guided to the sheet processing unit via the sheet conveying path.

In such a sheet feeding apparatus, the optimum pressing force to be applied to the sheet to be fed to the sheet processing section differs depending on the thickness of the sheet, and when the pressing force to be applied to the sheet is constant, If a sheet having a thickness different from the pressing force is attempted to be fed, when the sheet is thinner, a plurality of sheets are simultaneously fed, which causes double feeding, and when the sheet is thicker, the sheet is not fed. It is easy to make a mistake in sending.

Therefore, in Japanese Patent Laid-Open No. 4-223939, the pressing force of the pickup roller for feeding the sheet out of the accommodating means is changed according to the thickness of the sheet, so that sheets of various thicknesses can be stabilized. A configuration that enables pickup is disclosed.

[0005]

However, in the above-mentioned conventional method, although the performance at the time of picking up the sheet from the accommodating means is improved, the feeding force of the separating means for guiding the sheets one by one to the sheet conveying path thereafter. If it is not taken into consideration and the sheet fed out from the storing means is thick or the sheet is stiff, the feeding force of the separating means is insufficient and the sheet conveyance stops, and even if the sheet is in a proper state, it is more than that. There is a problem that the feeding cannot be continued because the feeding cannot be continued. In particular, when there is a bent portion in the sheet conveying path, a large feeding force is required for the separating means composed of the sheet feeding roller, the separating roller, etc., and the above problems are more likely to occur.

For example, in an image forming apparatus as a sheet processing apparatus, with the downsizing of the apparatus in recent years, a recording sheet as a sheet is horizontally stored in a container, and a pair of recording sheets fed out from the container is provided. In many cases, the rollers are guided to an image forming section which is a sheet processing section via a vertical sheet conveyance path. In this way, when the conveyance direction of the recording sheet is abruptly bent in the sheet conveying path from the accommodating unit to the image forming unit, thick recording paper or stiff recording sheet is conveyed from the accommodating unit to the bending section after being picked up. Since the resistance force at this time becomes large, a large feeding force is required for the separating means.

An object of the present invention is to change the separating pressure when a sheet feeding error occurs in which the sheet feeding is stopped after the leading edge of the sheet fed out from the accommodating means passes through the separating means during the sheet feeding operation. By performing the sheet feeding operation again by increasing the feeding force of the separating means, it is possible to cope with thick sheets and strong sheets, and it is possible to reliably prevent the occurrence of feeding errors. An object of the present invention is to provide an image forming apparatus including a sheet feeding method and a sheet feeding device.

[0008]

[Means for Solving the Problems] (1) In a state where sheets fed out from a containing means containing a plurality of sheets are separated one by one through a separating means that applies a separating pressure to the sheets. In a sheet feeding device that feeds to a sheet processing unit of a main body device, a pressure changing unit that changes the separation pressure of a separating unit and a detecting unit that detects a feeding error are provided, and the detecting unit feeds after the feeding operation. When the occurrence of an error is detected, the separating pressure of the separating means is changed by the pressure changing means, and the feeding operation is performed again.

In this structure, when a feeding error occurs in the sheet fed out from the accommodating means, the feeding operation is performed again with the separation pressure changed. Therefore, when the separating pressure acting on the sheet from the separating means is insufficient and the sheet cannot be fed, the feeding operation is repeated with the separating pressure of the separating means changed, and the separating pressure is fed. The sheet is reliably fed by being optimized for the thickness of the sheet and the strength of the waist.

(2) The pressure changing means changes the separation pressure when the detecting means detects the occurrence of a feeding error in any of a predetermined number of consecutive feeding operations.

In this structure, the separating pressure applied to the sheet from the separating means is changed when the sheet feeding error occurs repeatedly a predetermined number of times during the sheet feeding operation. Therefore, the feeding operation is repeated without changing the separation pressure until the feeding errors continue for a predetermined number of times, and the separation pressure is changed in a situation where a reason other than insufficient separation pressure can be considered as the cause of the feeding error. However, the separation pressure applied to the sheet from the separation means is changed only in a situation where it is unlikely that a feeding error has occurred due to a cause other than insufficient separation pressure. As a result, the probability of occurrence of double feeding due to excessive separation pressure is reduced in the feeding operation after a feeding error other than the insufficient separation pressure has occurred.

(3) The pressure changing means changes the separating pressure acting on the sheet from the separating means to a high pressure side.

In this structure, the separating pressure applied to the sheet from the separating means is increased in the feeding operation after the feeding error occurs. Therefore, when a feeding error occurs due to a low separating pressure acting on the sheet as compared with the thickness of the sheet to be fed and the strength of the waist, the cause is reliably eliminated.

(4) The sheet processing unit of the main body apparatus in a state where the sheets fed from the accommodating means that accommodates a plurality of sheets are separated one by one through the separating means that exerts a separating pressure on the sheets. In the sheet feeding method of feeding to the sheet, when a sheet feeding error occurs after the feeding operation,
It is characterized in that the separating pressure of the separating means is changed and the feeding operation is performed again.

In this structure, when a feeding error occurs in the sheet fed out from the accommodating means, the feeding operation is performed again with the separation pressure changed. Therefore, when the separating pressure acting on the sheet from the separating means is insufficient and the sheet cannot be fed, the feeding operation is repeated with the separating pressure of the separating means changed, and the separating pressure is fed. The sheet is reliably fed by being optimized for the thickness of the sheet and the strength of the waist.

(5) The sheet feeding device according to any one of (1) to (3) is provided, and the fed sheet is subjected to image forming processing in an image forming section which is a sheet processing section. Characterize.

In this structure, when a feeding error of the sheet to be fed to the image forming unit for performing the image forming process on the sheet occurs, the separating pressure acting on the sheet from the separating unit is changed and the sheet is again fed. The feeding operation is repeated. Therefore, even in the image forming apparatus in which the bent portion is formed in the sheet conveying path with the downsizing of the apparatus, the feeding force of the sheet is reduced and thus the sheet feeding error is likely to occur. The separating pressure optimum for the thickness of the sheet to be fed and the strength of the waist acts on the sheet from the separating means, and the sheet is reliably fed toward the image forming unit.

(6) It is characterized in that setting means is provided for receiving a setting input as to whether or not the separation pressure is changed by the pressure changing means.

In this structure, in the feeding operation after the feeding error occurs, the setting input as to whether to change the separating pressure applied to the sheet from the separating means is accepted. Therefore, it becomes possible to change the setting of whether the separation pressure is variable or constant depending on whether the thickness of the seat or the strength of the waist stored in the storage means changes. It is possible to prevent double feed due to change in separation pressure when a feeding error occurs in a situation where the strength does not change.

(7) A storage unit for storing the change frequency of the separation pressure by the pressure changing unit is provided, and the initial set value of the separation pressure is changed according to the change frequency stored in the storage unit. .

In this structure, the initial value of the separation pressure set in the separation means is changed based on the history of changes in the separation pressure. Therefore, in a situation where a large number of feeding errors occur in the environment where the stiffness of the sheet becomes strong or the environment where the separation pressure is reduced, or when the thickness of the sheet or the strength of the stiffness is frequently changed. , The separation pressure is set high from the beginning, and the frequency of feeding errors decreases.

(8) The operation of changing the separation pressure by the pressure changing means is enabled or disabled according to the type of the sheet stored in the storing means.

In this structure, whether or not the separation pressure is changed in the feeding operation after the feeding error occurs is selected depending on the type of the sheet accommodated in the accommodating means. Therefore, when a feeding error occurs in the feeding operation of a thicker sheet or a stronger sheet than usual, a separation pressure suitable for the thickness and the firmness of the sheet acts on the sheet to be fed, Sheets are reliably fed. On the other hand, when a feeding error occurs in the feeding operation of a sheet thinner than usual or a sheet with a weak waist, an excessive separation pressure acts on the sheet to be fed compared to its thickness or waist strength. The occurrence of double feeding is reliably prevented. As a result, a good feeding operation is always performed regardless of the type of sheet to be fed.

(9) A sheet conveying path having a bent portion is formed between the accommodating means and the image forming portion.

In this structure, there is a bent portion in the sheet conveying path through which the sheets separated from each other after being fed out from the accommodating means pass, and the sheet is fed by the large conveying resistance at the bent portion. In an image forming apparatus that is prone to errors, the separation pressure in the feeding operation after a feeding error occurs is changed. Therefore, the sheet is reliably fed even in the image forming apparatus having a configuration in which a feeding error is likely to occur.

[0026]

1 is a schematic diagram showing a configuration of an image forming apparatus to which a sheet feeding apparatus according to an embodiment of the present invention is applied. The image forming apparatus 100 is configured by arranging a document reading section 110 at the top, an image forming section 210 at the center, and a sheet feeding section 250 at the bottom. A transparent glass platen 11 placed on the upper surface of the image forming apparatus 100.
An automatic document feeder 112 that automatically feeds a plurality of documents set on a document set tray one by one onto a document table 111 is provided on the first unit 1. A post-processing unit 260 is mounted on one side surface of the image forming unit 210, and a multi-stage paper feeding unit 270 also serving as a mounting table is arranged below the paper feeding unit 250.

The document reading section 110 located below the document table 111 is a first scanning unit 113, a second scanning unit 114, an optical lens 115 and a photoelectric conversion element C.
An automatic document feeder 1 having a CD line sensor 116
By the operation related to 12, the image of the document placed on the document table 111 is relatively scanned and read at a predetermined exposure position. The first scanning unit 113 is equipped with an exposure lamp unit that exposes the surface of the original, and a first mirror that reflects a reflected light image from the original in a predetermined direction. The second scanning unit 114 has a second mirror and a third mirror that guide the reflected light from the document reflected by the first mirror to the CCD line sensor 116, which is a photoelectric conversion element. The optical lens 115 reflects the light reflected from the document by C
An image is formed on the light receiving surface of the CD line sensor 116.

The original image read by the original reading unit 110 is sent as image data to an image data input unit (not shown), and after predetermined image processing is performed on the image data, it is stored in the memory of the image processing unit. The image forming unit 210 stores the image once and then reads the image in the memory according to the output instruction.
Transferred to.

The image forming section 210, which is the sheet processing section of the present invention, is provided with a laser according to image data transferred from the charger 223 for charging the photosensitive drum 222 to a predetermined potential, the document reading section 110, or an external device. A laser writing unit 227 that emits light to form an electrostatic latent image on the photosensitive drum 222, supplies toner to the electrostatic latent image formed on the photosensitive drum 222, and visualizes the toner image. Developing device 22
4, a transfer device 225 that transfers the toner image formed on the photoconductor drum 222 to a sheet, the photoconductor drum 2 after the transfer process
Cleaning device 2 for collecting toner and the like remaining on 22
26, a peeling device 229 for peeling the sheet from the photosensitive drum 222 after the transfer process is provided. Further, in the image forming unit 210, a fixing unit 217 for fixing the toner image on the paper by heating and pressing the paper on which the toner image is transferred.
Is provided. Further, on the discharge side of the fixing unit 217, a switchback path 221 for reversing the front and back of the sheet in the double-sided image forming mode in which images are formed on both sides of the sheet.
Are formed.

The sheet on which the toner image has been fixed in the fixing unit 217 is switched back to the switchback path 221 if necessary.
After that, the paper is guided to the post-processing device 260 by the paper ejection roller 219, where post-processing such as stapling and punching is performed, and then the paper is ejected onto the tray 261.

The paper feeding unit 250 is composed of a manual feed tray 254 mounted on the side of the main body, a duplex unit 255, a paper feed tray 251 and paper feed trays 252 and 253 provided in the multi-stage paper feed unit 270. . Further, these paper feed trays 251, 252, 253, 254 are the accommodating means of the present invention, and the paper (the sheet of the present invention) fed from these is transferred to the photosensitive drum 222 in the image forming section 210. It is provided with a conveying means 250 for conveying to a transfer position between the container 225 and the container 225. Duplex unit 255
Is connected to a switchback path 221 for reversing the sheet, and temporarily stores the sheet whose front and back surfaces are reversed in the double-sided image forming mode. The duplex unit 255 can be replaced with a normal paper feed tray.

FIG. 2 is a view showing the arrangement of the sheet feeding apparatus according to the embodiment of the present invention. The sheet feeding device 30 according to the embodiment of the present invention is formed in a part of the sheet feeding unit 250. The control unit 20 that controls the sheet feeding device 30 includes an operation unit 21, a storage unit 22, a drive motor 1 above the sheet conveyance path, a conveyance clutch 2, a sheet feed clutch 4, a sheet feed solenoid 7, and a separation solenoid. 15 is connected. The control unit 20 outputs drive data to the transport clutch 2, the paper feed clutch 4, the paper feed solenoid 7, and the separation solenoid 15 according to the operation content of the operation unit 21 and the program stored in the storage unit 22.

The transport clutch 2 is turned on / off based on the drive data output from the control unit 20, and the vertical portion 256 of the paper transport route 256 which is the sheet transport route of the present invention.
The rotation of the drive motor 1 is selectively transmitted to the conveyance roller 3 arranged at c. The paper feed clutch 4 is turned on / off based on the drive data output from the control unit 20, and the horizontal unit 256 of the paper transport path 256 on the right side of the paper feed tray 251.
a, the sheet feeding roller 5 and the sheet feeding tray 251.
The rotation of the drive motor 1 is selectively transmitted to the pickup roller 6 facing the upper surface of the inner sheet. Transport roller 3,
The paper feed roller 5 and the pickup roller 6 are rotated in the directions of the arrows by the rotational force of the drive motor 1 transmitted via the transport clutch 2 and the paper feed clutch 4.

The paper feed solenoid 7 is turned on / off based on the drive data output from the control unit 20, and selectively brings the pickup roller 6 into contact with the upper surface of the paper in the paper feed tray 251. The separation solenoid 15 is turned on / off based on the drive data output from the control unit 20, and is arranged below the support plate 11 that supports the separation roller 9 that is the separation means of the present invention via the torque limiter 10. The slide member 14 is moved horizontally. The slide member 14 has an upper surface provided with an inclined surface on which the hemispherical pressing member 13 abuts. The pressing member 13 is the compression spring 1.
It is supported by the bottom surface of the support plate 11 via the two. Also,
The separation roller 9 supported by the support plate 11 via the torque limiter 10 is in contact with the paper feed roller 5 at the horizontal portion 256 a of the paper transport path 256.

Therefore, the separation solenoid 15 is turned on / off.
When the slide member 14 moves in the horizontal direction by being turned off, the vertical position of the pressing member 13 that contacts the inclined surface changes. As a result, the compression spring 12 expands and contracts, and the upward biasing force acting on the support plate 11 from the compression spring 12 increases and decreases, and the contact force of the separation roller 9 to the sheet feeding roller 5 changes. These compression spring 12 and pressing member 1
3, the slide member 14 and the separating solenoid 15 constitute the pressure changing means of the present invention.

Separation roller 9 in paper transport path 256
A detector 8 for detecting the presence / absence of a sheet is provided between the sheet feeding roller 3 and the conveying roller 3. The detector 8 is the detecting means of the present invention, and is a contact type read sensor or photosensor provided with an actuator that comes into contact with a sheet, or a non-emitter in which a light projecting element and a light receiving element are arranged with the sheet transport path 256 interposed therebetween. Contact photosensors are commonly used. The image forming apparatus according to this embodiment uses a contact-type photo sensor.

FIG. 3 is a diagram for explaining a normal conveyance state of the sheet in the sheet feeding device. The control unit 20
When a paper feed request is made from the operation unit 21 by operating the start button or the like, the drive motor 1 and the transport clutch 2 are turned on to rotate the transport roller 3. In this state, the control unit 2
When 0 turns on the paper feed clutch 4, the paper feed roller 5 and the pickup roller 6 rotate. Further, when the control unit 20 turns on the sheet feeding solenoid 7, the pickup roller 6 comes into contact with the upper surface of the sheet surface in the sheet feeding tray 251, and the pickup roller 6 rotates in the direction of the arrow so that the sheet is fed one by one. It is fed toward between the paper feed roller 5 and the separation roller 9.

When the front end of the paper is conveyed to the paper feed roller 5 and the separation roller 9, the paper passes between the paper feed roller 5 and the separation roller 9 by the rotation of the paper feed roller 5 in the direction of the arrow, and is further conveyed. Paper feed path 2 after being fed horizontally
The bent portion 256 b and the vertical portion 256 c of the sheet 56 are conveyed in order to be conveyed upward, and the image is formed by the conveying roller 3 in the image forming unit 2.
It is transported to 10. When the paper passes through the bent portion 256b of the paper transport path 256, the detector 8 detects this and the feeding of the paper is confirmed. When the detector 8 detects the leading edge of the sheet, the sheet feeding solenoid 7 is turned off, and the pickup roller 6 is separated from the upper surface of the sheet in the sheet cassette 251. Further, in order to prevent double feed of the paper, the rear end of the paper is 30 mm before the paper feed roller 5 after the detector 8 detects the front end of the paper.
When the position is reached, the paper feed clutch 4 is turned off.

The timing of turning off the paper feed clutch 4 is the timing at which the detector 8 detects the front edge of the paper, the length of the paper to be fed in the feeding direction, and the paper feed from the detector 8 in the paper conveyance path. It is calculated based on the distance to the roller 5 and the sheet feeding speed.

In this feeding operation, the paper feed tray 251
Even if the next sheet is conveyed to the sheet feeding roller 5 along with the uppermost sheet in the above, since the torque limiter 10 is attached to the separation roller 9 that follows the sheet feeding roller 5, two or more sheets are If an attempt is made to enter between the paper feed roller 5 and the separation roller 9, the load increases and the separation roller 9
Stops. Therefore, two or more sheets are not fed between the paper feed roller 5 and the separation roller 9.

FIG. 4 is a diagram for explaining a feeding state when a sheet feeding error occurs in the sheet feeding device. After being picked up from the paper feed tray 251 by the pickup roller 6, the paper whose front end has passed between the paper feed roller 5 and the separation roller 9 due to the rotation of the paper feed roller 5 cannot pass through the bent portion 256b. In this case, the detector 8 does not detect the sheet even after the lapse of a predetermined time, and from this state, the control unit 20 determines that a feeding error has occurred.
In this case, the control unit 20 causes the contact force of the separation roller 9 to the paper feed roller 5, that is, the paper feed roller 9 between the paper feed roller 5 and the separation roller 9 by the pressure changing operation described below.
The separation pressure acting on the paper is changed to a high pressure and the paper is fed again.

When the detector 8 does not detect the sheet even after a lapse of a predetermined time after the start of the feeding operation, the control section 20
The separation solenoid 15 is turned on to move the slide member 14 in the direction of arrow A. Then, the position on the slope of the slide member 14 with which the pressing member 13 abuts changes from the low position side to the high position side, and the pressing member 13 is lifted in the arrow B direction,
The compression spring 12 contracts, and the elastic force that acts as an upward biasing force from the compression spring 12 to the support plate 11 increases. As a result, the contact force of the separation roller 9 with respect to the paper feed roller 5 is increased, and the separation pressure acting on the sheet sandwiched between the paper feed roller 5 and the separation roller 9 is increased from 300 to 350 g when the pressure is low to a high pressure. 450-550g of time
Rise to.

The conveyance direction of the sheet conveyance path 256 is the bent portion 2.
In the configuration in which the horizontal portion 256a is rapidly bent to the vertical portion 256c at 56b, when thick paper or strong paper fed from the paper feed tray 251 by the pickup roller 6 is fed through the paper transport path 256, The resistance force acting on the paper at the bent portion 256b becomes large, and a large paper feeding force by the paper feed roller 5 and the separation roller 9 is required to continue the paper feeding in the paper transport path 256. . In such a case, the separation pressure acting on the sheet from the separation roller 9 is increased and the sheet is fed again, so that the sheet feeding force by the sheet feeding roller 5 and the separation roller 9 is increased, and the sheet is fed for the second time. The sheet can be fed through the bending portion 256b during the feeding operation. Further, it becomes difficult for a feeding error due to insufficient separation pressure to occur, and proper feeding can be performed.

FIG. 5 is a flowchart showing a processing procedure at the time of sheet feeding operation in the control section of the image forming apparatus. When a paper feed request is made from the operation unit 21, the control unit 20 first drives the transport roller 3 (s1) and sets the separation pressure to be applied to the paper from the separation roller 9 based on the initial setting (s2). ). Specifically, the separation solenoid 1
The position of the slide member 14 is selected depending on whether or not the switch 5 is turned on, and the contact force of the compression spring 12 acting on the separation roller 9 via the support plate 11 to the sheet feeding roller 5 by the displacement in the vertical direction. Adjust. Next, the control unit 20 drives the paper feed roller 5 and also drives the pickup roller 6 to move it downward to start feeding the paper (s3).

After that, the control unit 20 determines whether or not the detector 8 has detected the paper and turned on before the predetermined time has passed (s4), and the detector 8 detects the paper within the predetermined time. If detected, the sheet feeding solenoid 7 is turned off after the number of sheet feedings is added, and the feeding operation is completed (s11, s12).

When the detector 8 does not detect the paper within the predetermined time, the control unit 20 turns off the paper feed clutch 4 and the paper feed solenoid 7 and then turns them on again to change the separation pressure. Without driving the pickup roller 6, the pickup roller 6 is driven and lowered again to perform the re-feeding operation. Whether or not the detector 8 has detected the sheet and turned on before a predetermined time elapses. Discrimination is performed (s5, s6).
When the sheet is fed by this re-feeding operation and the detector 8 is turned on, the control unit 20 turns off the sheet feeding solenoid 7 after adding the number of feedings and completes the feeding operation (s11, s1).
2).

If the detector 8 does not detect the paper within the predetermined time even in the re-feeding operation, the control unit 20 causes the paper feeding tray 251 used for feeding to accommodate thin paper. Whether or not the setting is set is determined (s7), and if the sheet feeding tray 251 that is set to accommodate thin sheets is used, it is determined that a sheet jam has occurred and the feeding operation is stopped (s7). → s9). At this time, the control unit 20 displays on the display of the operation unit 21 that the occurrence of the paper feed jam is notified, and the image forming operation in the image forming apparatus 100 is stopped.

When the paper feed tray 251 in use is not set to accommodate thin paper, the control section 20 determines whether or not the current separation pressure is the maximum value (s
8) If the current separation pressure is the maximum value, it is determined that a paper jam has occurred and the feeding operation is stopped (s8 → s9).
If the current separation pressure is not the maximum value, the control unit 20
The feeding operation is repeatedly executed with the separation pressure increased (s10 → s3).

With the above processing, in the image forming apparatus according to this embodiment, when a paper feeding error occurs during the paper feeding operation without causing an increase in cost due to the addition of a new feeding roller, The separation pressure acting on the paper from the separation roller 9 was increased and the paper was fed again to increase the paper feeding force of the paper feed roller 5 and the separation roller 2.
It is possible to feed the sheet via the bending portion 256b during the feeding operation after the fourth time. Further, it becomes difficult for a feeding error due to insufficient separation pressure to occur, and proper feeding can be performed.

Further, in the above process, the separating pressure acting on the sheet from the separating roller 9 is increased only when the feeding error occurs repeatedly in the two feeding operations under the same separating pressure. . Thereby, when a feeding error occurs due to a cause other than the insufficient separation pressure, it is possible to increase the separation pressure and prevent the double feeding due to the re-feeding operation.

Further, in the image forming apparatus 100 according to this embodiment, when paper is fed from the paper feed tray 251 which is set to accommodate thin paper, separation is performed even if a feeding error occurs. The pressure is never increased. As a result, it is possible to prevent the occurrence of double feeding due to the excessive separating pressure acting from the separating roller 9 as compared with the thickness of the paper to be fed and the strength of the waist.

In the above process, the re-feeding operation with the same separation pressure is performed only once, but the re-feeding operation may be performed twice or more. This further increases the possibility that it is possible to prevent the occurrence of double feeding due to increasing the separation pressure and performing the re-feeding operation when a feeding error occurs due to a cause other than the insufficient separation pressure.

Further, the operation unit 21 may accept a setting input by an operator or a serviceman whether or not to change the separation pressure when a paper feeding error occurs. This makes it possible to reliably prevent the occurrence of double feed after a feed error occurs, especially when feeding paper that is thinner than normal paper, and it is possible to use multiple types with different thickness and waist strength. Paper can always be fed in its best condition. In this case, a detection unit for detecting the thickness of the sheet is provided, and whether or not the separation pressure is changed can be automatically set based on the detection result of the detection unit when a sheet feeding error occurs. You may do it.

Further, the separation pressure may be changed not only in two steps but also in a plurality of steps or steplessly. In this case, instead of the separation solenoid 15, the slide member 14
A motor or the like that can control the movement amount of the step in multiple steps or steplessly is used. This makes it possible to finely set the separation pressure for various types of paper with different thicknesses and waist strength,
The feeding operation can be performed in a more optimal state.

In addition, the number of changes or the frequency of change of the separation pressure may be counted, and the initial setting of the separation pressure may be changed according to the number of changes or the change frequency. For example, when operating in an environment where the paper becomes stiff or where the separation pressure is low, or when heavy paper is used a lot, frequent feeding errors occur, which often cause separation. A pressure change is made. In such a case, that is, when the number of changes of the separation pressure or the change frequency exceeds a certain value, it is possible to reduce the number of occurrences of feeding error by performing the conveyance at a high separation pressure in the initial setting. The operating efficiency of the forming apparatus can be improved.

In the above embodiment, the image forming apparatus has been described as an example, but the present invention is also applicable to other sheet processing apparatuses having a sheet processing section for processing the sheet fed from the accommodating means. It can be implemented similarly.

[0057]

According to the present invention, the following effects can be obtained.

(1) When a feeding error occurs in the sheet fed from the accommodating means, the feeding operation is performed again with the separating pressure changed, so that the separating pressure acting on the sheet from the separating means is reduced. If the sheet cannot be fed due to a shortage, by repeating the feeding operation while changing the separation pressure of the separating means, the separation pressure can be adjusted to the thickness of the sheet to be fed and the strength of the waist. The optimal state can be achieved, and the sheet can be reliably fed regardless of the thickness and the strength of the waist.

(2) When a feeding error during the feeding operation is repeated a predetermined number of times, the separating pressure applied to the sheet from the separating means is changed so that the sheet is separated until the feeding error is repeated a predetermined number of times. The feeding operation is repeated without changing the pressure, and when there is a sufficient reason other than the insufficient separation pressure as the cause of the feeding error, the separation pressure is not changed and the feeding is performed due to something other than insufficient separation pressure. The separation pressure applied to the sheet from the separation means is changed only in a situation where it is considered that the possibility of occurrence of a mistake is low, and the separation operation is performed in the feeding operation after the occurrence of a feeding error other than the insufficient separation pressure. The probability of occurrence of double feed due to excessive pressure can be reduced, and the operating efficiency of the device can be improved.

(3) In the feeding operation after the feeding error occurs, the separating pressure applied from the separating means to the sheet is increased so that the thickness of the sheet to be fed and the strength of the waist are increased. When a feeding error occurs due to a low separation pressure acting on the sheet, the cause can be reliably eliminated, and the sheet can be reliably fed.

(4) When an error occurs in the feeding of a sheet to be fed to the image forming unit for performing the image forming process on the sheet, the separating pressure acting on the sheet from the separating means is changed and the sheet is fed again. By repeating the operation, a bent portion is formed in the sheet conveying path along with the downsizing of the apparatus, and therefore, even in the image forming apparatus in which the sheet feeding error is likely to occur due to the reduction in the sheet feeding force, The separating pressure optimum for the thickness of the sheet to be fed to the forming unit and the strength of the waist can be applied to the sheet from the separating unit, and the sheet can be reliably fed to the image forming unit.

(5) In the feeding operation after the feeding error has occurred, the setting input of whether or not to change the separating pressure applied to the sheet is received from the separating means, whereby the sheet stored in the storing means is received. Depending on whether or not the thickness or waist strength changes, it is possible to change the setting of whether the separation pressure is variable or constant, and it is possible to make a feeding error when the sheet thickness or waist strength does not change. It is possible to prevent the occurrence of double feed due to the change of the separation pressure when the above occurs.

(6) Based on the history of changes in separation pressure,
By changing the initial value of the separation pressure set in the separation means, when the environment where the stiffness of the sheet becomes strong or the environment where the separation pressure is decreased, or the thickness of the sheet or the strength of the stiffness is frequent. If a large number of feeding errors occur when the setting is changed to, the separation pressure can be set to a high value from the beginning in advance, and the frequency of feeding errors can be reduced.

(7) A thicker sheet than usual is selected by selecting whether or not to change the separation pressure in the feeding operation after the feeding error occurs, depending on the type of the sheet accommodated in the accommodating means. If a feeding error occurs in the feeding operation of a sheet with high rigidity or stiffness, the separating pressure suitable for the thickness of the sheet and the strength of the stiffness can be applied to the sheet to be fed, and the sheet can be securely attached. Can be delivered to. on the other hand,
When a feeding error occurs in the feeding operation of a thinner than normal sheet or a sheet with a weak waist, excessive separation pressure does not act on the sheet to be fed compared to the thickness or the strength of the waist. Therefore, double feeding can be reliably prevented. As a result, a good feeding operation can always be performed regardless of the type of sheet to be fed.

(8) There is a bent portion in the sheet conveying path through which the sheets separated one by one after being fed out from the accommodating means pass, and the sheet receives a large conveyance resistance at the bent portion, so that a feeding error may occur. In the image forming apparatus that is likely to occur, by changing the separating pressure in the feeding operation after the occurrence of the feeding error, it is possible to reliably feed the sheet even in the image forming apparatus that is likely to cause the feeding error. it can.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a configuration of an image forming apparatus to which a sheet feeding apparatus according to an embodiment of the present invention is applied.

FIG. 2 is a diagram showing a configuration of a sheet feeding device according to an embodiment of the present invention.

FIG. 3 is a diagram illustrating a normal conveyance state of a sheet in the sheet feeding device.

FIG. 4 is a diagram illustrating a conveyance state when a sheet feeding error occurs in the sheet feeding apparatus.

FIG. 5 is a flowchart showing a processing procedure during a paper feeding operation in the control unit of the image forming apparatus.

[Explanation of symbols]

1-drive motor 2-transport clutch 3-conveyor roller 4-paper feed clutch 5-paper feed roller 6-pickup roller 7-Paper feeding solenoid 8-detector 9-separation roller 10-Torque limiter 11-support plate 12-compression spring 13-Pressing member 14-slide member 15-isolation solenoid 100-Image forming apparatus 251-Paper Tray 256-Paper transport path 256b-bent

Continued front page    (72) Inventor Kozo Yamaguchi             22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka             Inside the company (72) Inventor Masanobu Yamamoto             22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka             Inside the company (72) Inventor Masahiko Fujita             22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka             Inside the company F term (reference) 3F343 FA02 FB02 FB03 FB04 FC01                       GA01 GB01 HA33 JD09 JD33                       KB05 LA04 LA13 LA14 LB08                       LC06 LC07 LD04 LD11 LD26                       LD30 MA03 MA14 MA15 MA22                       MA54 MC02 MC11 MC12 MC23

Claims (9)

[Claims] 1. A sheet processing unit of a main body device in a state where sheets fed out from a containing means containing a plurality of sheets are separated one by one through a separating means for exerting a separating pressure on the sheets. In the sheet feeding apparatus for feeding, a pressure changing means for changing the separation pressure of the separating means and a detecting means for detecting a feeding error are provided, and when the detecting means detects the occurrence of the feeding error after the feeding operation. Further, the sheet feeding device is characterized in that the separating pressure of the separating means is changed by the pressure changing means and the feeding operation is performed again. 2. The pressure changing means changes the separation pressure when the detecting means detects the occurrence of a feeding error in any of a predetermined number of consecutive feeding operations. The sheet feeding device described. 3. The sheet feeding apparatus according to claim 1, wherein the pressure changing unit changes the separating pressure acting on the sheet from the separating unit to a high pressure side. 4. A sheet processing unit of a main body device in a state where sheets fed from a containing means containing a plurality of sheets are separated one by one through a separating means for exerting a separating pressure on the sheets. A sheet feeding method for feeding a sheet, wherein when a sheet feeding error occurs after the sheet feeding operation, the separating pressure of the separating means is changed and the sheet feeding operation is performed again. 5. The sheet feeding device according to claim 1, wherein the fed sheet is subjected to an image forming process in an image forming unit which is a sheet processing unit. Image forming apparatus. 6. The image forming apparatus according to claim 5, further comprising setting means for receiving a setting input as to whether or not the separation pressure is changed by the pressure changing means. 7. A storage unit for storing the frequency of change of the separation pressure by the pressure changing means, wherein the initial setting value of the separation pressure is changed according to the change frequency stored in the storage unit. Item 7. The image forming apparatus according to Item 5 or 6. 8. The image forming apparatus according to claim 5, wherein the changing operation of the separation pressure by the pressure changing means is enabled or disabled according to the type of the sheet stored in the storing means. 9. The image forming apparatus according to claim 5, wherein a sheet conveying path having a bent portion is formed between the accommodating means and the image forming portion.