JP5168032B2 - Automatic document feeder and image forming apparatus - Google Patents

Description

  The present invention relates to an automatic document feeder that separates documents one by one from a bundle of documents set in a document setting section and conveys them to an image reading position, and an image forming apparatus including the automatic document feeder.

  Patent Document 1 discloses an automatic document feeder that separates documents one by one from a bundle of documents set in a document setting section and conveys them to an image reading position of an image reading apparatus. In this automatic document feeder, the skew of the document is corrected by abutting against the pair of transport rollers stopped before the separated document is transported to the image reading position.

  This inclination correction is performed by overfeeding the separated document after it has been abutted against the stopped pair of transport rollers and then fed by a predetermined amount until it is pressed against the pair of transport rollers. . At this time, the leading edge of the document is strongly pressed and aligned with the nip of the conveying roller pair.

  That is, since the inclination correction is performed so that the leading edge of the document is parallel to the nip of the pair of conveying rollers, it is desirable that the nip be parallel to the reading line of the image reading apparatus. However, in reality, the nip of the conveying roller pair may not be parallel to the reading line due to variations in component dimensions and assembly.

  On the other hand, a technique is known in which the angle of the axis of the driven roller of the conveying roller pair with respect to the document width direction is changed so that the nip of the conveying roller pair is parallel to the reading line (known technique).

JP 2004-83210 A

  However, the amount of the abutting document cannot be changed according to the angle of the driven roller shaft with respect to the document width direction. Therefore, there is a problem that the amount of abutment becomes excessive, the leading edge of the document is bent, or the document is jammed. On the other hand, if the amount of abutment is insufficient, there is a problem that the inclination of the original cannot be corrected and the quality of the read image is deteriorated. That is, if the angle of the driven roller shaft with respect to the document width direction is changed, it is difficult to accurately correct the document inclination.

  Therefore, the present invention provides an automatic document feeder that can accurately correct the inclination of a document even if the angle of the axis of the driven roller with respect to the document width direction is changed, and an image forming apparatus including the automatic document feeder. For the purpose of provision.

In order to solve the above-mentioned problem, the invention described in claim 1 is an automatic document conveying device that separates documents one by one from a bundle of documents set in a document setting unit and conveys them to an image reading position. A conveyance member that conveys a document; a conveyance roller pair that is located downstream of the conveyance member in the document conveyance direction and conveys the document; and a control unit that controls driving of the conveyance member and the conveyance roller pair. The conveyance member is driven and a document is abutted against the nip of the stopped conveyance roller pair by a predetermined amount to correct the inclination of the document. The conveyance roller pair includes a driving roller and a driven roller. an angle changing mechanism for changing the angle with respect to the document width direction of the axis, an operation portion for operating the angle changing mechanism, and a angle detecting means for detecting an angle with respect to the document width direction of the axis of the driven roller, the control unit, the driven Roller shaft The greater angle relative to draft the width direction, characterized in that to increase the abutment of the document to the conveying roller pair stopped.

According to a second aspect of the present invention, in the first aspect of the present invention, a predetermined threshold value to be compared with the angle of the shaft of the driven roller with respect to the document width direction is input to the control unit in advance. The document abutment amount is changed with this threshold as a boundary .

The invention described in claim 3 is the invention described in claim 1 or 2 , further comprising a motor for driving the conveying member and a timer for measuring the driving time of the motor, and the controller is configured to control the shaft of the driven roller. When the original abutment amount according to the angle with respect to the original width direction is converted into a motor drive time according to the motor drive linear velocity, and the inclination of the original is corrected, the motor is driven for this converted time. It is characterized by.

According to a fourth aspect of the present invention, in the first or second aspect of the present invention, the motor includes a motor that drives the conveying member, and a driving amount measuring unit that measures the driving amount of the motor. The original abutment amount corresponding to the angle of the axis of the original with respect to the original width direction is converted into a drive amount of the motor , and when the inclination of the original is corrected, the motor is driven by this converted drive amount. To do.

The invention described in claim 5 includes the automatic document feeder according to any one of claims 1 to 4, reads an image of a document conveyed by the automatic document feeder, and reads the read image. The image forming apparatus is formed on a recording medium .

  According to the present invention, the angle detection unit detects the angle of the driven roller shaft with respect to the document width direction, and the control unit changes the amount of the document conveying roller pair abutted on the nip according to this angle. Even if the angle of the shaft of the driven roller with respect to the document width direction is changed, the document inclination can be corrected with high accuracy. Accordingly, it is possible to prevent the amount of abutment from becoming excessive, and it is possible to prevent the document from being bent at the front end and from being jammed. In addition, since the amount of abutment can be prevented from being insufficient, it is possible to reliably correct the inclination of the document and to prevent the quality of the read image from being deteriorated.

  Hereinafter, a first embodiment of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a cross-sectional view of the periphery of the driven roller of the automatic document feeder according to the present embodiment, and shows a state in which the axis of the driven roller is inclined with respect to the document width direction. FIG. 2 is a cross-sectional view of the periphery of the driven roller of the automatic document feeder according to the present embodiment, and shows a state in which the axis of the driven roller is parallel to the document width direction. 3 is a cross-sectional view of the periphery of the driven roller and the angle changing mechanism of the automatic document feeder according to the present embodiment. FIG. 4A is a perspective view of the adjustment dial and the variable resistor. It is a figure which shows the state before a knob of a variable resistance fits. FIG. 4B is a perspective view of the adjustment dial and the variable resistor, and shows a state where the shaft of the adjustment dial and the knob of the variable resistor are fitted. FIG. 5 is a graph showing the relationship between the document abutting amount and the angle of the driven roller shaft with respect to the document width direction, and FIG. 6 shows the document abutting at the time of document skew correction in the automatic document feeder according to the present embodiment. FIG. 7 is a block diagram showing a control configuration at the time of document skew correction in the automatic document feeder according to the present embodiment, and FIG. 8 is a block diagram showing the control according to the present embodiment. FIG. 9 is a longitudinal sectional view showing a schematic configuration of the automatic document feeder, and FIG. 9 is a perspective view showing a schematic configuration of the image forming apparatus according to the present embodiment.

  The image forming apparatus 1 according to the present embodiment is a copying machine. As shown in FIG. 9, the automatic document feeder 3 that transports a document to an image reading position 20 (see FIG. 8) and the image reading position 20. An image reading unit 4 that reads an image of an original, an image forming unit 5 that forms an image of the original read by the image reading unit 4 on a recording medium (paper), and a supply that houses a recording medium supplied to the image forming unit 5 A paper cassette 7 and a paper discharge unit 11 for discharging a recording medium on which an image is formed by the image forming unit 5 are provided. The image forming apparatus 1 includes a control unit 39 and an operation panel 36 that transmits an operation signal such as a paper feed signal to the control unit 39.

  The automatic document feeder 3 is mounted on the upper part of the image forming apparatus 1 and is provided so as to be openable and closable with respect to the main body of the image forming apparatus 1 by a hinge.

  As shown in FIG. 8, the automatic document feeder 3 is provided with a document tray (document setting unit) 13 into which a document T (a sheet or a bundle of sheets) is inserted and set. It has been. On the downstream side of the document tray 13 in the document transport direction, a calling roller 15 that feeds the document T set on the document tray 13 and a separation that separates and feeds only the topmost document from the document T sent by the calling roller 15. A feeding unit 17 is provided. On the downstream side of the separation feeding unit 17, the first conveyance path A that guides the document fed by the separation feeding unit 17 to the image reading position 20, and the document T that has passed the image reading position 20 on the downstream side. A second transport path B for guiding is provided. On the downstream side of the second conveyance path B, a switching claw 21 for switching the conveyance destination of the document guided by the second conveyance path B, a discharge unit 23 for stacking the documents guided by the switching claw 21, and a switching claw 21 Are provided with a pair of reversing rollers 24a and 24b for switching back the document guided by. A third transport path C is provided between the vicinity of the tip of the switching claw 21 and the first transport path A to join the switched back document to the first transport path A.

  In the upstream portion of the first conveyance path A, a pair of pull-out rollers (conveyance roller pair) 25 and 26 for conveying a document is provided. In the vicinity of the upstream side of the pair of pull-out rollers 25 and 26, an abutment sensor 43 is provided. Is provided.

  On the upstream side of the image reading position 20, a reading entrance roller pair 27 is provided that conveys the document conveyed from the separation feeding unit 17 toward the image reading position 20. On the downstream side of the image reading position 20, a reading exit roller pair 29 is provided that conveys the document that has passed the image reading position 20 to the downstream side. A paper discharge roller 31 is provided downstream of the second conveyance path B.

  A paper feed cover 45 is provided on the upper part of the automatic document feeder 3 so as to be openable and closable by a hinge with respect to an apparatus main body (hereinafter referred to as an apparatus main body). That is, by opening the paper feed cover 45, the inside of the apparatus is exposed.

  The document tray 13 is inclined so as to be lowered from the upstream side in the document transport direction to the downstream side in the document transport direction.

  The calling roller 15 is pivotally supported at the other end of an arm 33 supported at one end by the main body of the automatic document feeder 3 and rotatable. That is, the calling roller 15 has a standby position above the document T set on the document tray 13 (the position indicated by the solid line in FIG. 8) and a contact position that contacts the upper surface of the document T (the position indicated by the two-dot chain line in FIG. 8). ). The calling roller 15 is driven by a solenoid. When the solenoid is energized, the calling roller 15 rotates from the standby position toward the contact position. When the solenoid is de-energized, the call roller 15 rotates from the contact position toward the standby position. It comes to move. The solenoid is controlled by the control unit 39.

  A document set sensor 41 for detecting whether or not a document T is set on the document tray 13 is provided between the document tray 13 and the separation feeding unit 17. The document set sensor 41 is connected to the control unit 39. In the vicinity of the document setting sensor 41, a document stopper that receives the leading edge of the document T set on the document tray 13 is provided. The document stopper is in contact with the leading edge of the document T and the contacting position. It is possible to turn to a retracted position for retracting. The document stopper is controlled by the control unit 39.

  The separation feeding unit 17 is provided in contact with the paper feeding belt (conveying member) 38 that feeds the uppermost document from the document T fed from the document tray 13 and the lower document as a document. And a reverse roller 40 that returns to the tray 13 side.

  The paper feed belt 38 is an endless belt-like member and is wound around a belt driving roller 65 and a belt driven roller 67. The belt drive roller 65 is driven by a DC motor 51 via a drive transmission member such as a gear, and the DC motor 51 is controlled by a control unit 39. The control unit 39 drives the paper feed belt 38 to abut a predetermined amount of the original against the nip between the stopped pull-out roller pair 25 and 26 to correct the inclination of the original.

  The reverse roller 40 is rotatably supported by the apparatus main body, and is driven to rotate in a direction opposite to the driving direction of the paper feeding belt 38 via a torque limiter.

  That is, in the separation feeding unit 17, the sheet feeding belt 38 circulates and moves in the sheet feeding direction, and the reverse roller 40 rotates in the direction opposite to the sheet feeding direction, so that the separation nip (the sheet feeding belt 38 and the reverse roller) is rotated. Only the uppermost document is separated from the document T fed to the nip 40) and fed. When the torque applied to the reverse roller 40 exceeds a predetermined value, the driving force to the reverse roller 40 is not transmitted by the torque limiter, and the reverse roller 40 rotates with the document.

  The pull-out roller pair 25, 26 is composed of a drive roller 25 and a driven roller 26 that contacts the drive roller 25 from above.

  As shown in FIG. 1, the driven roller 26 includes three roller portions 26a, 26a, and 26b and a shaft 53 that fixes these rollers.

  Each roller portion 26 a is disposed at each end of the shaft 53, and the roller portion 26 c is disposed at the center of the shaft 53.

  The shaft 53 of the driven roller 26 is rotatably supported by a rectangular parallelepiped bracket 57 via bearing members 55 and 55.

  A cylindrical pin 59 is fixed to the side surface 58 of the end surface 58 on the downstream side of the document conveying direction of the bracket 57 and along the direction orthogonal to the document width direction (perpendicular to the paper surface). The pin 59 is supported by the apparatus main body and rotatably with respect to the apparatus main body in the circumferential direction.

  As shown in FIG. 3, a pinion gear 61 is fixed coaxially to the pin 59. The pinion gear 61 meshes with the spur gear 63, and the spur gear 63 is coaxially fixed to the adjustment dial (operation unit) 64.

  That is, when the adjustment dial 64 and the spar gear 63 are rotated, the pinion gear 61 is rotated and the pin 59 is rotated. It comes to move. Thereby, the angle of the shaft 53 of the driven roller 26 with respect to the document width direction can be changed. Note that a mechanism including the pinion gear 61, the spur gear 63, and the adjustment dial 64 is referred to as an angle changing mechanism.

  As shown in FIG. 1, an arcuate guide hole 65 centered on a pin 59 is formed in the center of the upper end of the bracket 57 on the upstream side in the document conveying direction. A fixed guide pin 67 is inserted. That is, when the bracket 57 is rotated, the guide hole 65 is moved along the guide pin 67 to guide the rotation of the bracket 57.

  As shown in FIG. 4A, one end portion 70 of the shaft 69 of the adjustment dial 64 has a substantially cross-shaped ridge, and is attached to a knob 71 a built in the housing of the variable resistance (angle detection means) 71. It fits in the formed substantially cross-shaped groove 72 (see FIG. 4B). The knob 71a rotates in the circumferential direction with respect to the casing of the variable resistor 71. That is, when the adjustment dial 64 is turned, the knob 71a is rotated so that the resistance value R of the variable resistor 71 is changed.

  The variable resistor 71 is connected to the control unit 39 and calculates an angle θ of the shaft 53 of the driven roller 26 with respect to the document width direction from the resistance value R.

  The configuration of the control unit 39 will be described with reference to FIG. The resistance value storage unit 73 stores the resistance value R of the variable resistor 71. When the resistance value R is changed, the resistance value R is stored in place of the resistance value R before the change. It is supposed to be.

  The resistance value comparison unit 75 compares the current resistance value of the variable resistor 71 with the resistance value (previously stored value) already stored by the resistance value storage unit 73. The determination unit 76 determines the situation based on the comparison result of the resistance value comparison unit 75.

  The angle calculation unit 77 calculates the angle of the shaft 53 of the driven roller 26 with respect to the document width direction based on the resistance value R.

  The abutting amount calculation unit 79 calculates the document abutting amount Y against the pull-out roller pair 25 and 26 based on the angle calculated by the angle calculation unit 77. Incidentally, the relationship between the document abutting amount Y and the angle θ of the driven roller 26 with respect to the document width direction of the shaft 53 is proportional as shown in FIG.

  The drive time calculation unit 81 calculates the document abutment amount Y calculated by the abutment amount calculation unit 79 by converting it into the drive time of the motor 51 corresponding to the motor drive linear velocity.

  The timer 83 starts counting when the abutting sensor 43 detects a document when correcting the document tilt, and ends counting when the driving time of the motor 51 calculated by the driving time calculation unit 81 elapses. is there.

  The operation of the automatic document feeder 3 according to the present embodiment will be described with reference to FIGS. Initially, as shown in FIG. 2, the shaft 53 of the driven roller 26 is parallel to the document width direction. In this state, when the read image of the document is disturbed, the user rotates the shaft 53 of the driven roller 26 by a predetermined angle so that the nip of the pull-out roller pair 25 and 26 is parallel to the reading line (see FIG. 1). The shaft 53 is rotated by opening the paper feed cover 45 and rotating the adjustment dial 64 by a predetermined amount. The resistance value storage unit 73 stores a resistance value R (previous storage value) of the variable resistance before the shaft 53 of the driven roller 26 is rotated. The determination unit 76 always determines whether or not the resistance value R is different from the previous acquired value (S1). When the adjustment dial 64 is rotated, the resistance value R of the variable resistor 71 changes. At this time, the determination unit 76 determines that the resistance value R is different from the previous acquired value based on the comparison result of the resistance value comparison unit 75 (YES in S1). Then, the angle calculation unit 77 calculates the angle θ based on the resistance value R, and the abutment amount calculation unit 79 calculates the abutment amount Y according to the calculated angle θ (S2). The abutting amount Y is calculated as an amount proportional to the angle of θ. Further, the drive time calculation unit 81 converts the calculated abutment amount Y into a motor drive time corresponding to the motor drive linear velocity.

  Next, the document T is set on the document tray 13. The document T is set by abutting one end (tip) of the document T in the longitudinal direction against the document stopper at the contact position. When the document T is set (in response to a detection signal from the document setting sensor 41) and a paper feed signal is received from the operation panel 36, the control unit 39 moves the document stopper to the retracted position and moves the calling roller 15 After the rotation drive is started, the solenoid is energized to start the contact operation of the calling roller 15. When the calling roller 15 comes into contact with the document T, the document T is sent out toward the separation feeding unit 17.

  When the document T enters the separation nip, the uppermost document moves in the moving direction of the paper feed belt 38 due to friction with the paper feed belt 38, while the lower document is clockwise (opposite of the paper feed belt 38). It is returned to the document tray 13 side by friction with the rotating reverse roller 40. In this way, the uppermost document is separated from the lower document.

  The uppermost document separated by the separation feeding unit 17 is further fed by the sheet feeding belt 38, the leading edge is detected by the abutting sensor 43, and further advances to the nip of the pull-out roller pair 25, 26 in the stopped state. bump into. Thereafter, the control unit 39 retracts the calling roller 15 from the upper surface of the document T, and a predetermined time (time calculated by the drive time calculation unit 81) measured by the timer 83 after the abutting sensor 43 detects the leading edge of the document. The paper feed belt 38 is driven. At this time, the shaft 53 of the driven roller 26 is inclined at an angle θ with respect to the document width direction, but the document is pulled by the pull-out roller pair 25 by an abutment amount Y corresponding to the angle θ. It hits 26 nips. Accordingly, the document can be pressed against the nip between the pull-out roller pairs 25 and 26 with a predetermined amount (necessary amount) of bending, and the inclination of the document can be accurately corrected. The document whose inclination has been corrected is inclined by θ with respect to the document conveyance direction and is pressed against the nip between the pull-out roller pair 25 and 26, and the leading edge of the document is the image reading unit 4. It is parallel to the reading line.

  After the inclination correction, the control unit 39 drives the driving roller 25 to convey the document downstream while sandwiching the document in the nip between the pull-out roller pair 25 and 26. Then, the original is conveyed toward the image reading position 20 by the reading entrance roller pair 27. Since the leading edge of the document is conveyed to the image reading position 20 in parallel with the reading line of the image reading unit 4, it is possible to prevent the reading image of the document from being disturbed.

  In the case of reading only the first image surface (single-sided mode), the document is read at the image reading position 20 and then passes through the second conveyance path B, and the switching claw 21 (FIG. 5) at the document discharge position. 8 is guided by the switching claw 21) located at the position indicated by the solid line and is discharged to the discharge portion 23.

  In the case of double-sided reading of a document (double-sided mode), the document passes through the first conveyance path A and image information is read at the image reading position 20 in order to read the first image surface. After the image reading, it passes through the second conveyance path B and is guided to the nip of the reversing roller pair 24a, 24b by the switching claw 21 at the document reversing position (the switching claw 21 at the position of the two-dot chain line in FIG. 8). It is conveyed downstream by a reversing roller 24a that rotates forward (rotates clockwise).

  When the document is discharged as it is after reading the second image surface, the document is switched back by the reverse rotation (rotation in the counterclockwise direction) of the reversing roller 24a and guided to the switching claw 21 at the document discharge position to be transported to the third transport. To route C. The original passes through the third conveyance path C through the first conveyance path A by the rotation of the discharge roller 31, the second image surface is read at the image reading position 20, and the original is discharged through the second conveyance path B. It is guided to the switching claw 21 at the position and discharged to the discharge unit 23.

  When the second image surface is read and then reversed again to adjust the page order, the document is reversed by the switching claw 21 at the document reversing position after the second image surface is read and through the second conveyance path B. Guided to the nip of the roller pair 24a, 24b. Then, it is switched back again by the pair of reversing rollers 24a and 24b, and is conveyed from the third conveyance path C toward the first conveyance path A. The document that has passed through the first transport path A and the second transport path B is guided to the switching claw 21 at the document discharge position and sent to the discharge unit 23, and the page order of the documents is adjusted.

  In the image forming apparatus 1, the recording medium is conveyed from the paper feed cassette 7 to the image forming unit 5. In the image forming unit 5, an image of a document read by the image reading unit 4 is formed on a recording medium. The recording medium on which the image is formed is discharged to the paper discharge unit 11.

  On the other hand, when there is no disturbance in the read image of the document, it is not necessary to rotate the shaft 53 of the driven roller 26, so the adjustment dial 64 is not rotated. Then, in S1 of FIG. 6, the determination unit 76 determines that the resistance value R is not different from the previous acquired value, and repeats the same determination (NO in S1). Accordingly, there is no change in the abutting amount Y, and the abutting amount Y is an amount corresponding to the previous acquired value of the resistance value R. Other controls are the same as when the original read image is disturbed.

  In this embodiment, the angle of the shaft 53 of the driven roller 26 with respect to the document width direction from the state in which the shaft 53 of the driven roller 26 is parallel to the document width direction (the state of θ = 0) is θ (θ is not 0). In the example described above, the shaft 53 of the driven roller 26 is rotated until the state becomes). However, for example, the shaft 53 of the driven roller 26 rotates from θ = θ1 (θ1 is not 0) to θ = θ2. The same applies when moving.

  The effect of this Embodiment is demonstrated. According to the present embodiment, the variable resistor 71 detects the angle θ of the driven roller 26 shaft 53 with respect to the document width direction, and the control unit 39 determines the nip between the document pull-out roller pairs 25 and 26 according to the angle θ. Since the abutment amount Y is changed, even if the angle θ of the shaft 53 of the driven roller 26 with respect to the document width direction is changed, the inclination of the document can be accurately corrected. Accordingly, since the abutting amount Y can be prevented from being excessive, it is possible to prevent the document from being bent at the front end and from being jammed. In addition, since it is possible to prevent the abutting amount Y from being insufficient, it is possible to reliably correct the inclination of the document and to prevent the quality of the read image from being deteriorated.

  Since the abutting amount Y of the document that abuts against the pair of pull-out rollers 25 and 26 increases as the angle θ of the driven roller 26 with respect to the document width direction of the shaft 53 increases, the excess or deficiency of the abutting amount Y of the document can be eliminated. it can.

  Since the control unit 39 converts the calculated abutment amount Y into a motor drive time corresponding to the motor drive linear speed, by driving the motor for the converted motor drive time, only the calculated abutment amount Y is obtained. You can be sure.

  It is possible to provide an image forming apparatus provided with an automatic document feeder that exhibits the same effects as described above.

  Next, other embodiments will be described. In the following description, parts having the same functions and effects as those of the first embodiment described above are denoted by the same reference numerals, and detailed description of the parts is given. In the following description, differences from the first embodiment will be mainly described.

  A second embodiment will be described with reference to FIGS. FIG. 10 is a flowchart showing the control of the automatic document feeder according to this embodiment, and FIG. 11 is a block diagram showing the control configuration of the automatic document feeder according to this embodiment.

  In the present embodiment, two threshold values A and B (<A) to be compared with the resistance value R of the variable resistor 71 are input to the control unit 39 in advance, and the amount of document abutting on the basis of these threshold values Y is changed. Further, the abutting amount Y when the threshold value A is equal to or greater than the threshold value A is set to α, the abutting amount Y when the threshold value B is equal to or larger than the threshold value A and β, and the abutting amount Y when the threshold value B is less than the threshold value B is set to γ.

  That is, as shown in FIG. 11, the control unit 39 includes a threshold stock unit 87 that stocks the threshold values A and B of the resistance value, and an abutment amount stock unit 89 that stocks the abutment amounts α, β, and γ. Further, an abutting amount determination unit 91 that determines an abutting amount Y with each threshold as a boundary is provided. The control unit 39 is not provided with the angle calculation unit 77 and the abutment amount calculation unit 79.

  In this embodiment, a stepping motor 97 is used as the drive motor for the belt drive roller 65. Then, the control unit 39 converts the determined abutment amount Y into the drive pulse number (drive amount) of the stepping motor 97 and calculates the drive pulse number calculation unit 93 and the calculated motor drive pulse number. A drive pulse number counting unit 95 for counting (measuring) is provided. The control unit 39 is not provided with the drive time calculation unit 81 and the timer 83.

  The operation related to the document inclination correction of the automatic document feeder 3 in the present embodiment will be described with reference to FIG. The determination unit 76 determines whether or not the resistance value R is different from the previous acquired value (S11). When it is determined that the resistance value R is not different from the previous acquired value (when it is determined that the angle θ has not changed), the determination unit 76 repeats the same determination. When it is determined that the resistance value R is different from the previous acquired value, the determination unit 76 determines whether the resistance value R is equal to or greater than the threshold A based on the comparison result of the resistance value comparison unit 75 (S12). ). When it is determined that the resistance value R is equal to or greater than the threshold value A, the abutment amount determination unit 91 determines the abutment amount Y as α (S13), and the flow ends. When it is determined that the resistance value R is less than the threshold value A, the determination unit 76 determines whether the resistance value R is equal to or greater than the threshold value B based on the comparison result of the resistance value comparison unit 75 (S14). If it is determined that the value is equal to or greater than the threshold value B, the abutting amount determination unit 91 determines the abutting amount Y as β (S15), and the flow ends. When it is determined that the resistance value R is less than the threshold value B, the abutting amount determination unit 91 determines the abutting amount Y as γ (S16), and the flow ends.

  After the abutment amount Y is determined, the drive pulse number calculation unit 93 converts the abutment amount Y into the drive pulse number of the stepping motor 97. The drive pulse number counting unit 95 counts the number of drive pulses from when the abutting sensor 43 detects the leading edge of the document, and the stepping motor 97 is driven by the number of drive pulses.

  According to the present embodiment, the angle θ of the driven roller 26 with respect to the document width direction is compared with the predetermined thresholds A and B, and the abutting amount is changed with these thresholds as a boundary, so that the control becomes easy.

  In addition, since the abutting amount Y to be changed with the thresholds A and B as boundaries is set to predetermined amounts, α, β, and γ, it is not necessary to calculate the abutting amount Y, and the control can be simplified.

  Since the control unit 39 converts the calculated abutment amount Y into a motor drive pulse of the stepping motor 97, by driving the stepping motor 97 by the converted motor drive pulse, the calculated abutment amount Y is reliably obtained. Can be faced.

  It is possible to provide an image forming apparatus provided with an automatic document feeder that exhibits the same effects as described above.

  In addition, this invention is not limited to the above-mentioned embodiment, A various deformation | transformation is possible in the range which does not deviate from the summary. For example, in the embodiment described above, the adjustment dial 64 is manually rotated to change the angle of the shaft 53 of the driven roller 26 with respect to the document width direction. Instead, the adjustment dial 64 is rotated by a motor. The angle of the shaft 53 of the driven roller 26 with respect to the document width direction may be changed by operating this motor with the operation panel 36.

  In the second embodiment, two threshold values for the resistance value R are input to the control unit 39 and three abutting amounts Y are input thereto. However, the present invention is not limited to this, and the threshold value for the resistance value R is set. N (> 2) pieces may be inputted, and (N + 1) abutting amounts Y may be inputted. Alternatively, one threshold value of the resistance value R may be input and two abutting amounts Y may be input.

  In the above-described embodiment, the paper feeding belt 38 is used as the conveying member of the separation feeding unit 17, but a paper feeding roller may be used instead. In this case, a separation pad may be provided in contact with the sheet feeding roller instead of the reverse roller 40 as the separation member of the separation feeding unit 17.

  In the above-described embodiment, the sheet feeding belt (conveying member) 38 is driven and the document is abutted against the pull-out roller pair (conveying roller pair) 25 and 26 to correct the inclination of the document. It is also possible to correct the inclination of the original by driving the paper feed belt 38 and the driving roller 25 so that the original is brought into contact with the nip of the reading entrance roller pair (conveying roller pair) 27. In this case, the angle of the shaft of the driven roller of the reading entrance roller pair 27 with respect to the document width direction is changed, and the driving of the paper feeding belt 38 and the driving roller 25 is synchronized (the driving roller 25 is driven by the belt). It is driven by the same motor as the roller 65).

FIG. 3 is a cross-sectional view of the periphery of a driven roller of the automatic document feeder according to the first embodiment, showing a state in which the axis of the driven roller is inclined with respect to the document width direction. FIG. 3 is a longitudinal sectional view of the periphery of a separation feeding unit in a plain paper document mode of the automatic document feeder according to the first embodiment. FIG. 3 is a cross-sectional view of the periphery of a driven roller of the automatic document feeder according to the first embodiment, and shows a state in which the axis of the driven roller is parallel to the document width direction. FIG. 3 is a cross-sectional view of the periphery of a driven roller and an angle changing mechanism of the automatic document feeder according to the first embodiment. (A) is a perspective view of an adjustment dial and a variable resistance, and is a figure which shows the state before the axis | shaft of an adjustment dial and the knob of a variable resistance fit. (B) is a perspective view of an adjustment dial and a variable resistor, and shows a state in which the shaft of the adjustment dial and the knob of the variable resistor are fitted. 6 is a graph showing the relationship between the amount of document abutment and the angle of the driven roller shaft with respect to the document width direction. 6 is a flowchart illustrating control of calculating a document abutting amount when correcting the skew of the document in the automatic document feeder according to the first embodiment. FIG. 3 is a block diagram illustrating a control configuration at the time of correcting a document inclination in the automatic document feeder according to the first embodiment. 1 is a longitudinal sectional view illustrating a schematic configuration of an automatic document feeder according to a first embodiment, and is a perspective view illustrating a schematic configuration of an image forming apparatus according to the first embodiment. 1 is a perspective view illustrating a schematic configuration of an image forming apparatus according to a first embodiment. 6 is a flowchart illustrating control of an automatic document feeder according to a second embodiment. FIG. 10 is a block diagram illustrating a control configuration of an automatic document feeder according to a second embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 3 Automatic document feeder 13 Document tray (document setting part)
20 Image reading position 25 Drive roller 26 Driven roller 38 Paper feed belt (conveying member)
39 Control unit 53 Driven roller shaft 71 Variable resistance (angle detection means)
A Resistance value threshold B Resistance value threshold T Document Y Abutting amount α Abutting amount β Abutting amount γ Abutting amount θ Angle of driven roller shaft with respect to document width direction

Claims (5)

An automatic document feeder that separates documents one by one from a bundle of documents set in a document setting section and conveys the documents to an image reading position, a conveyance member that conveys the document, and a downstream of the conveyance member in the document conveyance direction A pair of conveying rollers positioned to convey the document and a control unit that controls driving of the conveying member and the conveying roller pair, and the control unit drives the conveying member to place the document in the nip of the conveying roller pair in a stopped state. The document is tilted in a fixed amount to correct the inclination of the document, and the conveying roller pair is composed of a driving roller and a driven roller. An angle changing mechanism for changing the angle of the axis of the driven roller with respect to the document width direction, and an angle changing mechanism an operation section for operating, and a angle detecting means for detecting an angle with respect to the document width direction of the axis of the driven roller, the control unit, the larger the angle with respect to the document width direction of the axis of the driven roller, the conveyance rollers in a stopped state An automatic document feeder, characterized in that to increase the abutment of the document to. A predetermined threshold value to be compared with the angle of the axis of the driven roller with respect to the document width direction is input in advance to the control unit, and the control unit changes the amount of document abutting on the threshold value. The automatic document feeder according to claim 1 . A motor for driving the conveying member and a timer for measuring the driving time of the motor are provided, and the control unit determines the amount of original abutting according to the angle of the shaft of the driven roller with respect to the original width direction according to the motor driving linear velocity. 3. The automatic document feeder according to claim 1 , wherein when correcting the inclination of the document in terms of motor driving time, the motor is driven for the converted time . A motor for driving the conveying member, and a drive amount measuring unit for measuring the drive quantity of the motor, the control unit, the abutment of the document in accordance with the angle with respect to the document width direction of the axis of the driven roller drive motor
3. The automatic document feeder according to claim 1, wherein when the inclination of the document is corrected in terms of a moving amount , the motor is driven by the converted driving amount . An automatic document feeder according to any one of claims 1 to 4 is provided, an image of a document conveyed by the automatic document feeder is read, and the read image is formed on a recording medium. Image forming apparatus .

Images