JP2015224118A - Feeding device, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a feeding device capable of suppressing excessive curvature of a sheet.SOLUTION: A feeding device 1 includes a register roller pair 24, a sending-out roller pair 22, a control section 90, and a curl-amount detection section 26. The register roller pair 24 corrects skew of a sheet P. The sending-out roller pair 22 sends out the sheet P to the register roller pair 24. The control section 90 deflects the sheet P by controlling the sending-out roller pair 22 to send out the sheet P to the stopped register roller pair 24. The curl-amount detection section 26 detects the curl amount of the sheet P. The control section 90 controls the register roller pair 24 and the sending-out roller pair 22 to impart deflection of a deflection amount according to the curl amount to the sheet P.

Description

  The present invention relates to a feeding device that feeds a sheet and an image forming apparatus.

  The image forming apparatus described in Patent Document 1 imparts deflection to a sheet by a pair of registration rollers in order to correct skew of the sheet. The image forming apparatus varies the amount of bending applied to the paper according to the type of paper.

  For recycled paper such as newspaper, the first curl is likely to occur. The first curl indicates that the paper is curved in a bow shape when the paper is viewed from the paper transport direction. It is difficult to correct the skew of the recycled paper even if the same amount of bending as that applied to the high-quality paper is given to the recycled paper on which the first curl has occurred.

  In view of this, the image forming apparatus described in Patent Document 1 makes the amount of bending applied to recycled paper larger than the amount of bending applied to high-quality paper.

JP-A-4-64553

  However, the image forming apparatus described in Patent Document 1 has the following problems. That is, the user may use the paper once used for printing, so-called back paper, as the paper for printing again. Since the paper once used for printing passes through the fixing unit, a second curl may occur. The second curl indicates that the paper is curved in a bow shape when viewed from the paper width direction.

  When a sheet having a second curl is bent to correct the skew of the sheet, the amount of bending caused by the bending is added to the amount of curl caused by the second curl, and the sheet is excessively curved. The bend for correcting the skew of the paper is because, like the second curl, when the paper is viewed from the paper width direction, the paper is curved in a bow shape.

  Excessive curvature of the paper can cause jams, noise, and wrinkles. A jam is a phenomenon in which a sheet is jammed inside the image forming apparatus. The wrinkle indicates a state where the sheet is bent in the direction opposite to the direction of the bending due to the bending.

  That is, if the paper is too curved, the paper may not be properly conveyed to the nip of the registration roller pair, and jamming may occur. Further, not only the leading edge of the paper but also the surface of the paper abuts against the pair of registration rollers, so that noise may be generated. Furthermore, the sheet may be struck against the pair of registration rollers, and the sheet may be bent in the direction opposite to the direction of bending due to the bending.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a feeding device and an image forming apparatus that can suppress the sheet from being excessively curved.

  A feeding device according to a first aspect of the present invention includes a registration roller pair, a feeding roller pair, a control unit, and a curl amount detection unit. The registration roller pair corrects the skew of the sheet. The feeding roller pair sends the sheet to the registration roller pair. The control unit bends the sheet by controlling the feeding roller pair and feeding the sheet toward the resist roller pair that is stopped. The curl amount detection unit detects the curl amount of the sheet. The control unit controls the registration roller pair and the delivery roller pair to impart a deflection amount corresponding to the curl amount to the sheet.

  An image forming apparatus according to a second aspect of the present invention includes a feeding device according to the first aspect and an image forming unit. The image forming unit forms an image on the sheet fed by the feeding device.

  According to the present invention, since the sheet is bent according to the curl amount of the sheet, it is possible to suppress the sheet from being excessively curved.

1 is a schematic cross-sectional view illustrating an internal structure of an image forming apparatus according to an embodiment of the present invention. (A)-(c) It is a schematic diagram explaining the control which provides a sheet | seat with the feeding apparatus which concerns on embodiment of this invention. It is a schematic diagram explaining the control which provides bending to the curled sheet | seat by the feeder which concerns on embodiment of this invention. It is a figure explaining the bending control by the feeder which concerns on embodiment of this invention. It is a flowchart which shows the bending control method by the feeding apparatus which concerns on embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof is not repeated. In the present embodiment, the X axis, the Y axis, and the Z axis are orthogonal to each other, the X axis and the Y axis are parallel to the horizontal plane, and the Z axis is parallel to the vertical line.

  An image forming apparatus 100 according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 shows the internal structure of the image forming apparatus 100. In the present embodiment, the image forming apparatus 100 is a multifunction machine having functions of a copying machine, a printer, and a facsimile machine.

  The image forming apparatus 100 includes a feeding device 1, an image forming unit 50, a fixing unit 60, a discharge unit 65, a document conveying unit 70, an image reading unit 75, and an operation unit 80.

  The feeding device 1 includes a feeding unit 10, a plurality of conveying roller pairs 20, a sending roller pair 22, a registration roller pair 24, a curl amount detection unit 26, a sheet detection unit 28, and a control unit 90. Prepare. The feeding unit 10 includes a plurality of cassettes 12 and a manual feed tray 14.

  The control unit 90 controls each element of the feeding device 1. The control unit 90 controls each element of the image forming apparatus 100.

  Sheets P are stacked on the cassette 12 and the manual feed tray 14. The sheet P is, for example, a paper sheet (for example, plain paper, recycled paper, thin paper, or thick paper) or a synthetic resin sheet (for example, an OHP (Overhead Projector) sheet). The sheet P is sent from the cassette 12 or the manual feed tray 14 toward the conveyance roller pair 20. Then, the sheet P is conveyed to the image forming unit 50 by the conveying roller pair 20, the sending roller pair 22, and the registration roller pair 24.

  The sending roller pair 22 is disposed upstream of the registration roller pair 24 in the sheet conveying direction D (hereinafter referred to as “conveying direction D”). The sending roller pair 22 sends the sheet P to the registration roller pair 24.

  The registration roller pair 24 is disposed upstream of the image forming unit 50 in the transport direction D. The registration roller pair 24 corrects the skew of the sheet P and sends the sheet P toward the image forming unit 50 in accordance with the image formation timing.

  The curl amount detection unit 26 is disposed upstream of the sheet detection unit 28 in the transport direction D. For example, the curl amount detection unit 26 is disposed between the adjacent conveyance roller pair 20 and the conveyance roller pair 20. The curl amount detection unit 26 is preferably disposed at a position away from the transport roller pair 20. This is because curling is suppressed by the transport roller pair 20 in the immediate vicinity of the transport roller pair 20. For example, the curl amount detection unit 26 is disposed at an intermediate position between the adjacent conveyance roller pair 20 and the conveyance roller pair 20.

  The curl amount detection unit 26 detects the curl amount of the sheet P and outputs a detection signal to the control unit 90. The curl amount detection unit 26 includes, for example, a load cell, detects a pressing force applied to the load cell by the curled sheet P, and outputs a detection signal to the control unit 90. Since the pressing force to the load cell correlates with the curl amount, the detection of the pressing force corresponds to the detection of the curl amount. The curl amount detection unit 26 includes, for example, a light emitting element and a position detection element, detects the displacement of the light receiving position of the reflected light according to the curl of the sheet P, and outputs a detection signal to the control unit 90. Since the displacement of the light receiving position of the reflected light correlates with the curl amount, the detection of the displacement corresponds to the detection of the curl amount.

  The sheet detection unit 28 is disposed between the sending roller pair 22 and the registration roller pair 24. The sheet detection unit 28 detects the sheet P and outputs a detection signal to the control unit 90. In the present embodiment, the sheet detection unit 28 includes an actuator that rotates by contact of the sheet P, and a signal indicating that the actuator is rotated by the sheet P is output to the control unit 90 as a detection signal. Note that the sheet detection unit 28 is not limited to an actuator, and includes, for example, a photo interrupter, and can detect the sheet P by detecting light blocking or reflection by the sheet P.

  The image forming unit 50 forms an image on the sheet P fed by the feeding device 1. Specifically, the image forming unit 50 forms an image on the sheet P by the photosensitive drum 51, the charging unit 52, the exposure unit 53, the developing unit 54, and the transfer unit 55. In addition, the image forming unit 50 includes a cleaning unit 56 that removes residual toner from the photosensitive drum 51 and a static elimination unit 57 that removes residual charge from the photosensitive drum 51.

  The sheet P on which the image is formed is conveyed toward the fixing unit 60. The fixing unit 60 heats and pressurizes the sheet P to fix the image on the sheet P. The sheet P on which the image is fixed is conveyed toward the discharge unit 65. The discharge unit 65 discharges the sheet P.

  The document transport unit 70 transports the document toward the image reading unit 75. The image reading unit 75 reads an image of a document and generates image data. The operation unit 80 includes a display unit 82. The display unit 82 is, for example, a touch panel. The operation unit 80 receives various user operations and outputs operation signals to the control unit 90. The control unit 90 controls each element of the image forming apparatus 100 according to the operation signal. The display unit 82 displays various information related to the image forming apparatus 100 (for example, information set in the image forming apparatus 100, user operation information, or notification from the control unit 90).

  With reference to FIG. 2A to FIG. 2C, control (deflection control) for imparting deflection to the sheet P in order to correct the skew of the sheet P will be described. FIG. 2A to FIG. 2C show control for imparting bending to the sheet P that is not curled. The control unit 90 bends the sheet P by controlling the feeding roller pair 22 and feeding the sheet P toward the stopped registration roller pair 24. Deflection indicates that when the sheet P is viewed from the sheet width direction orthogonal to the conveyance direction D, the sheet is bent in an arcuate shape. The sheet width direction is along the Y axis.

  That is, as illustrated in FIG. 2A, the control unit 90 stops the rotation of the registration roller pair 24 and rotates the delivery roller pair 22. The sending roller pair 22 sends the sheet P toward the registration roller pair 24. As shown in FIG. 2B, the sheet P hits the nip of the resist roller pair 24 that is stopped. As shown in FIG. 2C, the sheet P bends because the feed roller pair 22 is rotating even after the sheet P hits the registration roller pair 24. Accordingly, the sheet P takes a posture along the registration roller pair 24, and the skew of the sheet P is corrected.

  Specifically, when the sheet detection unit 28 detects the sheet P, the control unit 90 rotates the resist roller pair 24 that is stopped when the deflection control time has elapsed since the sheet P was detected. The shorter the deflection control time, the smaller the deflection amount, and the longer the deflection control time, the larger the deflection amount. In the feeding device 1, a deflection control time of a constant value Tp is set. Therefore, the sheet P is given a specified deflection amount Dp corresponding to the constant value Tp.

  FIG. 3 shows control for imparting deflection to the curled sheet P. The curl indicates that the sheet P is bowed when viewed from the sheet width direction. The sheet should have no curl, but curl can occur due to various causes.

  The control unit 90 bends the sheet P by controlling the feeding roller pair 22 and feeding the curled sheet P toward the stopped registration roller pair 24. However, the control unit 90 controls the sending roller pair 22 and the registration roller pair 24 to impart to the sheet P a deflection amount corresponding to the curl amount detected by the curl amount detection unit 26. Accordingly, since the sheet P is bent according to the curl amount of the sheet P, the sheet P can be prevented from being excessively curved. As a result, the occurrence of jam, noise, and wrinkles on the sheet P can be suppressed.

  Details of the bending control according to the curl amount will be described with reference to FIGS. 3 and 4. The control unit 90 changes the time from when the sheet detection unit 28 detects the sheet P to when the resist roller pair 24 being stopped is rotated, that is, by changing the deflection control time, the amount of deflection applied to the sheet P is changed. Change.

  FIG. 4 shows the deflection control by the feeding device 1. When the curl amount of the sheet P satisfies the first condition, that is, when the curl amount is larger than the upper limit value TU, the control unit 90 causes the discharge unit 65 (FIG. 1) to form the sheet without forming an image on the sheet P. P is discharged. The upper limit value TU is, for example, 20 mm in the case of an A4 sheet.

  When the curl amount is larger than the upper limit value TU, jam, noise, or wrinkle may occur. Therefore, by discharging the sheet P, these problems are solved. Alternatively, the control unit 90 can notify the user that the sheet P is to be removed. For example, the control unit 90 causes the display unit 82 (FIG. 1) to display a sentence and / or an image that instructs to remove the sheet P.

  When the curl amount of the sheet P satisfies the second condition, that is, the curl amount is equal to or less than the upper limit value TU, and the total value of the specified deflection amount Dp and the curl amount is greater than the upper limit value TU. The sheet roller P is bent so that the total value of the bending amount and the curling amount (hereinafter referred to as “sheet bending amount”) matches the upper limit value TU by controlling the feeding roller pair 22 and the registration roller pair 24. I will. For example, in the case of an A4 sheet, the specified deflection amount Dp is 5 mm.

  Specifically, when the curl amount satisfies the second condition, the control unit 90 shortens the deflection control time to a value smaller than the constant value Tp so that the sheet bending amount matches the upper limit value TU. As a result, a bending amount smaller than the prescribed bending amount Dp is applied to the sheet P, and the sheet P is bent so that the sheet bending amount coincides with the upper limit value TU.

  For example, when the specified deflection amount Dp is 5 mm and the curl amount is 17 mm, the total value is 22 mm, which is larger than 20 mm (upper limit TU). Therefore, the control unit 90 shortens the bending control time from the constant value Tp so that the bending amount becomes 3 mm, and sets the sheet bending amount to 20 mm (upper limit TU).

  Even when the curl amount does not satisfy the first condition, if the total value of the specified deflection amount Dp and the curl amount is larger than the upper limit value TU, jam, noise, or wrinkle may occur. Therefore, these problems are solved by matching the sheet bending amount to the upper limit value TU. Further, the amount of deflection is not 0, and the deflection corresponding to the deflection control time is imparted to the sheet P, so that the skew of the sheet P can be corrected.

  When the curl amount of the sheet P satisfies the third condition, that is, the control unit 90, that is, the curl amount is not more than the upper limit value TU, and the total value of the prescribed deflection amount Dp and the curl amount is not more than the upper limit value TU. When the curl amount is larger than the lower limit value TL, the sheet roller P 22 and the registration roller pair 24 are controlled so that the sheet bending amount matches the total value of the prescribed deflection amount Dp and the lower limit value TL. Bend. For example, in the case of an A4 sheet, the lower limit TL is 10 mm.

  Specifically, when the curl amount satisfies the third condition, the control unit 90 is smaller than the constant value Tp so that the sheet bending amount matches the total value of the specified deflection amount Dp and the lower limit value TL. Deflection control time to value to shorten. As a result, a deflection amount smaller than the prescribed deflection amount Dp is applied to the sheet P, and the sheet P bends so that the sheet bending amount coincides with the total value of the prescribed deflection amount Dp and the lower limit value TL.

  For example, when the specified deflection amount Dp is 5 mm and the curl amount is 12 mm, the total value is 17 mm, which is larger than 10 mm (lower limit value TL). Therefore, the control unit 90 shortens the bending control time from the constant value Tp so that the bending amount becomes 3 mm, and sets the sheet bending amount to 15 mm (specified deflection amount Dp + lower limit value TL).

  Even when the amount of bending does not satisfy the first condition and the second condition, noise may occur if the curl amount is larger than the lower limit value TL. Therefore, this problem is solved by making the sheet bending amount coincide with the total value of the prescribed deflection amount Dp and the lower limit value TL. Further, the amount of deflection is not 0, and the deflection corresponding to the deflection control time is imparted to the sheet P, so that the skew of the sheet P can be corrected.

  In an environment in which noise is not a concern for the user, the control unit 90 gives a prescribed deflection amount Dp to the sheet P by setting the deflection control time to a constant value Tp according to an instruction from the user via the operation unit 80. You can also. Further, when the silent mode setting of the image forming apparatus 100 is cancelled, the control unit 90 can set the deflection control time to a constant value Tp and give the sheet P a specified deflection amount Dp. In these cases, the skew of the sheet P can be corrected more effectively than in the case where the deflection control time is shortened below the certain value Tp.

  When the curl amount of the sheet P satisfies the fourth condition, that is, when the curl amount is not less than 0 and not more than the lower limit value TL, the control unit 90 controls the feeding roller pair 22 and the registration roller pair 24. Then, the sheet P is imparted with a specified amount of deflection Dp.

  When the sheet P is not curled, the possibility of occurrence of jam, noise, and wrinkles is small. Even if the sheet P is curled, if the curl amount is less than or equal to the lower limit TL, the possibility of occurrence of jam, noise, and wrinkles is small. Therefore, when the curl amount satisfies the fourth condition, the sheet P is imparted with a specified amount of deflection Dp to more effectively correct the skew of the sheet P.

  The curl amount and the deflection amount correspond one-to-one, and the curl amount x (x is an arbitrary numerical value) millimeter and the deflection amount x millimeter are the same.

  With reference to FIGS. 3-5, the bending control method by the control part 90 of the feeder 1 is demonstrated. FIG. 5 is a flowchart showing a deflection control method.

  In step S1, the control unit 90 determines whether or not the curl amount detected by the curl amount detection unit 26 is greater than zero. Control part 90 advances control to Step S5, when affirmation judging is carried out (it is Yes at Step S1). On the other hand, when the negative determination is made (No in step S1), the control unit 90 satisfies the fourth condition and advances the control to step S3 because the curl amount is 0.

  In step S <b> 3, the control unit 90 gives the specified deflection amount Dp to the sheet P and ends the control.

  In step S5, the control unit 90 determines whether or not the curl amount is larger than the upper limit value TU. Control part 90 advances control to Step S9, when a negative judgment is made (it is No at Step S5). On the other hand, when the control unit 90 makes an affirmative determination (Yes in Step S5), that is, when the curl amount satisfies the first condition, the control proceeds to Step S7.

  In step S7, the control unit 90 causes the discharge unit 65 (FIG. 1) to discharge the sheet P without forming an image on the sheet P, and ends the control.

  In step S9, the control unit 90 determines whether or not the curl amount is equal to or less than the lower limit value TL. When the control unit 90 makes an affirmative determination (Yes in step S9), that is, when the curl amount satisfies the fourth condition, the control proceeds to step S3. On the other hand, when the control unit 90 makes a negative determination (No in step S9), the control proceeds to step S11.

  In step S11, the control unit 90 determines whether or not the total value of the prescribed deflection amount Dp and the curl amount is larger than the upper limit value TU. If the determination is positive (Yes in step S11), that is, if the curl amount satisfies the second condition, the control unit 90 advances the control to step S13. In step S13, the control unit 90 bends the sheet P so that the sheet bending amount coincides with the upper limit value TU, and ends the control. On the other hand, if the control unit 90 makes a negative determination (No in step S11), that is, if the curl amount satisfies the third condition, the control proceeds to step S15. In step S15, the control unit 90 deflects the sheet P so that the sheet bending amount matches the total value of the specified deflection amount Dp and the lower limit value TL, and ends the control.

  As described above with reference to FIGS. 1 to 5, according to the present embodiment, since the sheet P is bent according to the curl amount of the sheet P, the sheet P is excessively curved. Can be suppressed.

  The embodiments of the present invention have been described above with reference to the drawings. However, the present invention is not limited to the above-described embodiment, and can be implemented in various modes without departing from the gist thereof (for example, (1) to (4) shown below). In order to facilitate understanding, the drawings schematically show each component as a main component, and the thickness, length, number, and the like of each component shown in the drawings are different from the actual for convenience of drawing. In some cases. Moreover, the shape, dimension, etc. of each component shown by said embodiment are an example, Comprising: It does not specifically limit, A various change is possible in the range which does not deviate substantially from the effect of this invention.

  (1) The control unit 90 can change the constant value Tp, the upper limit value TU, and the lower limit value according to the size and / or material of the sheet P.

  (2) The control unit 90 executes the deflection control method of FIG. 5 without depending on the cause of the curl. Further, even when the curl direction of the sheet P is opposite to the curl direction shown in FIG. 3, the control unit 90 can execute the deflection control method of FIG. 5.

  (3) Although the mechanism for executing double-sided printing is omitted in FIG. 1, the image forming apparatus 100 can execute double-sided printing. When performing double-sided printing, the control unit 90 performs the deflection control of FIG. 5 in both feeding for forming an image on one side of the sheet and feeding for forming an image on the other side of the sheet. The method can be carried out.

  (4) The image forming apparatus 100 may be a multifunction machine including two devices of a copying machine, a printer, and a facsimile machine, or may be a printer, a copying machine, or a facsimile machine.

  The present invention can be used in the fields of a sheet feeding apparatus and an image forming apparatus that feed sheets.

DESCRIPTION OF SYMBOLS 1 Feeding device 22 Sending roller pair 24 Registration roller pair 26 Curl amount detection part 28 Sheet | seat detection part 50 Image forming part 90 Control part 100 Image forming apparatus P Sheet

Claims (7)

A pair of registration rollers that correct the skew of the sheet,
A pair of delivery rollers for feeding the sheet to the pair of registration rollers;
A controller that controls the delivery roller pair and deflects the sheet by feeding the sheet toward the resist roller pair that is stopped; and
A curl amount detection unit for detecting the curl amount of the sheet,
The said control part is a feeding apparatus which controls the said registration roller pair and the said sending roller pair, and gives the bending of the amount of bending according to the said curl amount to the said sheet | seat.   The control unit controls the registration roller pair and the delivery roller pair to impart a specified amount of bending to the sheet when the curl amount is 0 or more and less than a lower limit value. The feeding device described in 1.   The control unit according to claim 2, wherein when the curl amount is larger than an upper limit value, the control unit notifies the user that the sheet is discharged without forming an image on the sheet or the sheet is removed. Feeding device.   The control unit controls the registration roller pair and the delivery roller pair when the curl amount is equal to or less than the upper limit value and a total value of the prescribed deflection amount and the curl amount is larger than the upper limit value. The feeding device according to claim 3, wherein the sheet is bent so that a total value of the bending amount and the curl amount matches the upper limit value.   When the curl amount is less than or equal to the upper limit value, a total value of the prescribed deflection amount and the curl amount is less than or equal to the upper limit value, and the curl amount is greater than the lower limit value, The registration roller pair and the delivery roller pair are controlled to bend the sheet so that a total value of a deflection amount and a curl amount matches a total value of the specified deflection amount and the lower limit value. The feeding device according to claim 3 or claim 4. A sheet detector disposed between the pair of registration rollers and the pair of delivery rollers and further detecting the sheet;
6. The control unit according to claim 1, wherein the control unit changes a deflection amount to be applied to the sheet by changing a time from when the sheet is detected to when the resist roller pair being stopped is rotated. The feeding device according to any one of claims. A feeding device according to any one of claims 1 to 6,
An image forming apparatus comprising: an image forming unit that forms an image on the sheet fed by the feeding device.

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