JP5091029B2 - Automatic document feeder and image forming apparatus - Google Patents

Description

  The present invention relates to an automatic document conveyance device that discharges a document set in a document setting unit after the document is conveyed to an image reading position, and an image forming apparatus including the automatic document conveyance device.

  Patent Document 1 discloses an automatic document feeder that conveys a document set on a document tray to the image reading position and then ejects the document. In this automatic document feeder, when a document set on a document tray is sent out by a calling roller, if the document is not conveyed to the separation feeding unit within a predetermined reference time (non-feeding occurs), a call to the document is made. This non-feed is prevented by increasing the pressing force of the roller.

Japanese Patent No. 3974666

  However, since a pressing means such as an oil damper for pressing the calling roller against the document is required, there is a problem that the number of parts increases and the configuration becomes complicated. Also, if multiple overlapping originals are sent out while the pressing force of the calling roller is increased, the originals come into close contact with each other. There is a risk of feeding (multiple feeding).

  Accordingly, the present invention provides an automatic document conveying apparatus that can prevent non-feeding of a document in a document conveyance path from a document tray to a separation feeding unit and can prevent double feeding of documents in the separation feeding unit with a simple configuration; It is an object of the present invention to obtain an image forming apparatus provided with this automatic document feeder.

In order to solve the above-mentioned problem, the invention described in claim 1 is directed to a document tray on which a document is set, a call roller that feeds a document set on the document tray, and a document that is fed by the call roller. An automatic document feeder that separates and feeds the document fed from the separator feeding unit and transports the document to the image reading position, and the calling roller is disposed on the upper surface of the document. to being movable between abutting the abutting position and a standby position retracted from the contact position, and a document detection sensor for detecting the document in the document transport path from the document tray until the separation feeding section, the document a control unit for controlling the movement or rotation speed of the ductor roller receives a detection signal from the detection sensor, the jam sensor that transmits a detection signal to the control unit detects the jam of a document, Serial control unit, in response to the detection signal of the original detection sensor, together with the ductor roller changes the rotational speed of the contact with that time or the ductor roller on the document, the document detection after receiving the document conveyance start signal When it is determined that the time until the sensor detects the document is longer than a predetermined reference time, the withdrawal time of the calling roller is delayed from a preset withdrawal time, and the control unit It is determined that a jam has been detected when there is no change in the detection signal from the jam sensor for a predetermined time after receiving the start signal, and the original detection sensor detects the original after receiving the original transport start signal. If the time to longer than a predetermined reference time to, and wherein the delaying than the preset determination time when to determining that the detected jam

According to a second aspect of the present invention, there is provided a document tray on which a document is set, a calling roller that feeds a document set on the document tray, and a separation that separates and feeds the document fed by the calling roller one by one. An automatic document feeder that feeds the document fed from the separation feeding unit to the image reading position and then discharges the document. The calling roller is in contact with a contact position that contacts the upper surface of the document. A document detection sensor that can move between a standby position retracted from a contact position and detects a document in a document transport path from a document tray to the separation feeding unit, and receives a detection signal from the document detection sensor A control unit that controls the movement or rotation speed of the calling roller; and a jam sensor that detects a jam of the document and transmits a detection signal to the control unit. Depending on the difference between the detection signal, the with ductor roller changes the rotational speed of the time or the ductor roller is in contact with the document, from receiving the document conveyance start signal to the original detection sensor detects the document If the time is determined to longer than the predetermined reference time, the ductor roller same west rotational speed and feeding speed of the separating and feeding part of and, the control unit receives the document conveyance start signal From a time when the original detection sensor detects the original after receiving the original conveyance start signal. When the time is longer than a predetermined reference time, the time when it is determined that a jam has been detected is delayed from a predetermined time .

According to a third aspect of the present invention, there is provided a document tray on which a document is set, a calling roller for feeding a document set on the document tray, and a separation for separating and feeding the documents sent by the calling roller one by one. An automatic document feeder that feeds the document fed from the separation feeding unit to the image reading position and then discharges the document. The calling roller is in contact with a contact position that contacts the upper surface of the document. A document detection sensor that detects a document in a document transport path from the document tray to the separation feeding unit and receives a detection signal from the document detection sensor. A control unit that controls the movement or rotation speed of the calling roller, and a jam sensor that detects a jam of the document and transmits a detection signal to the control unit, and the control unit detects the document detection. In accordance with the detection signal of the sensor, the with ductor roller changes the rotational speed of the time or the ductor roller is in contact with the document, from receiving the document conveyance start signal to the original detection sensor detects the document If the time is determined to longer than the predetermined reference time, said delayed than ductor roller preset retracted timing the evacuation time of, and, the control unit is given from the jam sensor detects the document It is determined that a jam has been detected when there is no change in the detection signal from the jam sensor, and the time from when the document detection start signal is received until the document detection sensor detects the document is predetermined. When the time is longer than the reference time, the time when it is determined that a jam has been detected is delayed from a predetermined time .

According to a fourth aspect of the present invention, there is provided a document tray on which a document is set, a call roller that feeds a document set on the document tray, and a separation that separates and feeds the document that is fed by the call roller one by one. An automatic document feeder that feeds the document fed from the separation feeding unit to the image reading position and then discharges the document. The calling roller is in contact with a contact position that contacts the upper surface of the document. A document detection sensor that detects a document in a document transport path from the document tray to the separation feeding unit and receives a detection signal from the document detection sensor. A control unit that controls the movement or rotation speed of the calling roller, and a jam sensor that detects a jam of the document and transmits a detection signal to the control unit, and the control unit detects the document detection. In accordance with the detection signal of the sensor, the with ductor roller changes the rotational speed of the time or the ductor roller is in contact with the document, from receiving the document conveyance start signal to the original detection sensor detects the document When it is determined that the time is longer than a predetermined reference time, the rotation speed of the calling roller is made the same as the feeding speed of the separation feeding unit, and the control unit detects the document by the jam sensor. predetermined time after, the case where there is no change in the detection signal from the jam sensor is intended to determine that detects a jam, the time from receiving the document conveyance start signal to the original detection sensor detects the document Is longer than a predetermined reference time, the timing for judging that a jam has been detected is delayed from a preset judgment timing.

According to a fifth aspect of the present invention, there is provided a document tray on which a document is set, a calling roller that feeds a document set on the document tray, and a separation that separates and feeds the document that is fed by the calling roller one by one. An automatic document feeder that feeds the document fed from the separation feeding unit to the image reading position and then discharges the document. The calling roller is in contact with a contact position that contacts the upper surface of the document. A document detection sensor that detects a document in a document transport path from the document tray to the separation feeding unit and receives a detection signal from the document detection sensor. And a control unit that controls the movement or rotation speed of the calling roller, and the control unit is configured to detect when the calling roller is in contact with the document according to a detection signal of the document detection sensor. Alternatively, the rotation speed of the calling roller is changed, and the document detection sensor is a transmission type sensor or an ultrasonic sensor that can detect whether or not a plurality of documents are overlapped, and the control unit is configured to overlap a plurality of documents. If it is determined that the retraction time of the calling roller is earlier than the retraction time set in advance .

According to a sixth aspect of the present invention, there is provided a document tray on which a document is set, a calling roller for feeding a document set on the document tray, and a separation for separating and feeding the documents sent by the calling roller one by one. An automatic document feeder that feeds the document fed from the separation feeding unit to the image reading position and then discharges the document. The calling roller is in contact with a contact position that contacts the upper surface of the document. A document detection sensor that detects a document in a document transport path from the document tray to the separation feeding unit and receives a detection signal from the document detection sensor. And a control unit that controls the movement or rotation speed of the calling roller, and the control unit is configured to detect when the calling roller is in contact with the document according to a detection signal of the document detection sensor. Or change the rotational speed of the ductor roller, wherein the original detection sensor is a transmission type sensor or an ultrasonic sensor capable of detecting whether the overlapped plurality of originals, the control unit, the document is stacked plurality If it is determined that, characterized by less than the rotational speed of the rotational speed preset of the ductor roller.

The invention described in claim 7 includes the automatic document feeder according to any one of claims 1 to 6, and reads and reads the image of the document conveyed to the image reading position by the automatic document feeder. An image forming apparatus is characterized in that an image is formed on a recording medium .

  According to the present invention, for example, for a document with a strong non-feeding tendency (the timing detected by the document detection sensor is delayed), the control unit increases the time for which the calling roller contacts the document, thereby calling the document. Since the document conveyance time by the roller can be lengthened, non-feeding of the document in the document conveyance path from the document tray to the separation feeding unit can be prevented with a simple configuration without providing pressing means such as an oil damper. In addition, since the pressing force of the calling roller against the document is not increased by pressing means such as an oil damper, the documents are not brought into close contact with each other when a plurality of documents are fed out by the calling roller and separated and fed. It is possible to prevent double feeding of documents at the feeding unit.

  Also, for example, for a document with a strong non-feeding tendency, the control unit increases the rotation speed of the calling roller so that the document conveyance speed approaches the feeding speed of the separation feeding unit. It is possible to smoothly and reliably deliver the document to the section. Accordingly, non-feeding of the document in the document transport path from the document tray to the separation feeding unit can be prevented with a simple configuration that does not include pressing means such as an oil damper.

  Hereinafter, a first embodiment of the present invention will be described in detail with reference to the accompanying drawings. 1 is a longitudinal sectional view showing a schematic configuration of the automatic document feeder according to the present embodiment, and FIG. 2 is a flowchart showing control of the automatic document feeder according to the present embodiment. FIG. 4 is a block diagram illustrating a control configuration of the automatic document feeder according to the present embodiment, and FIG. 4 is a perspective view illustrating 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, and as shown in FIG. 4, an automatic document feeder 3 and an image reading unit 5 that reads an image of a document conveyed by the automatic document feeder 3. An image forming unit 7 that forms an image of a document read by the image reading unit 5 on a recording medium (paper), a paper feed cassette 9 that stores a recording medium supplied to the image forming unit 7, and an image forming unit 7. And a paper discharge unit 11 for discharging the recording medium on which the image is formed. The image forming apparatus 1 is provided with an operation unit 48 (see FIG. 3) that transmits an operation signal such as a paper feed signal (original conveyance start signal) to the control unit 39 described later.

  The automatic document feeder 3 is provided at the top of the image forming apparatus 1 so as to be opened and closed by a hinge. As shown in FIG. 1, the automatic document feeder 3 is provided with a document tray 13 into which a document T (one sheet or a bundle of sheets) is inserted and set. On the downstream side of the document tray 13 in the document transport direction, a call roller 15 that feeds the document T set on the document tray 13 and a separation feed that separates and feeds only the uppermost document from the document T sent by the call roller 15. A sending 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 19, and the document T that has passed the image reading position 19 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 first conveying path A, a pull-out roller pair 25 is provided on the upstream side, and a reading inlet roller pair 27 is provided on the downstream side. In the second conveyance path B, a reading exit roller pair 29 is provided on the upstream side, and a paper discharge roller 31 is provided on the downstream side.

  The document tray 13 is disposed so as to be gently inclined so as to be lowered toward the downstream side in the document conveyance direction.

  Between the document tray 13 and the separation feeding unit 17, a document set sensor 41 for detecting whether or not a document T is set on the document tray 13, a document detection sensor 43 for detecting a document, and a document jam And a jam sensor 45 for detecting the above are provided in this order from the upstream side in the document conveyance direction. The document set sensor 41, the document detection sensor 43, and the jam sensor 45 are connected to a control unit 39 described later. 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 transport path between the document tray 13 and the separation feeding unit 17 has a gentle downward slope from the document tray 13 to the intermediate part, and a steep upward slope from the intermediate part to the separation feeding part 17. Yes. That is, when the leading edge of the document bundle sent out by the calling roller 15 comes into contact with the rising slope of the intermediate portion, the leading edge of the document bundle is displaced and the document bundle is wound.

The calling roller 15 is pivotally supported by the other end of the arm 33 that can be turned around one end.
The arm 33 is driven by a solenoid 35. That is, the calling roller 15 has a standby position (a solid line position in FIG. 1) H above the document T set on the document tray 13 and a contact position (indicated by a two-dot chain line in FIG. It is possible to move between (position) K. The arm 33 is always urged toward the standby position H by a coil spring, and rotates when the solenoid 35 is energized from the standby position H toward the contact position K. When the energization of the solenoid 35 is cut off, the arm 33 abuts. It rotates from the position K toward the standby position H. The solenoid 35 is controlled by a control unit 39 described later.

  The retraction time when the calling roller 15 is retracted from the contact position K toward the standby position H is such that when the original is conveyed without slipping, the original fed by the calling roller 15 is separated from the separation nip of the separation feeding unit 17. It is set in advance at the time of reaching (between a paper feed belt 38 and a separation roller 40 described later) (0.4 seconds after the control unit 39 described later receives a paper feed signal from the operation unit 48). . The calling roller 15 is connected to the stepping motor 37 via a drive transmission member such as a gear, and is driven to rotate. The initial setting value (preset rotation speed) of the rotation speed of the calling roller 15 is higher than the movement speed of the paper feed belt 38 described later in order to prevent the original from being pushed into the separation feeding unit 17 and the original from being bent. 5% to 10% smaller. The stepping motor 37 is controlled by a control unit 39 described later.

  The separation feeding unit 17 includes a sheet feeding belt 38 wound around a driving roller 65 and a driven roller 67 and a separation roller 40 provided below the sheet feeding belt 38. That is, in the separation feeding unit 17, the sheet feeding belt 38 moves in the sheet feeding direction (clockwise in FIG. 1), and the separation roller 40 rotates in the same direction (clockwise in FIG. 1). Thus, only the uppermost sheet is separated and fed from the document T sent between the sheet feeding belt 38 and the separation roller 40.

  The configuration of the control unit 39 will be described with reference to FIG. The receiving unit 47 receives signals from the document set sensor 41, the document detection sensor 43, the jam sensor 45, and the operation unit 48 of the image forming apparatus main body.

  Based on the information from the receiving unit 47 and the measurement time of the timer 50, the comparison unit 49 receives a paper feed signal from the operation unit 48 and waits for the document detection sensor 43 to detect the document and a predetermined reference time. And compare. The reference time is the time from when the document is detected by the document detection sensor 43 until the document is detected by the document detection sensor 43 when the document is conveyed without slipping. It is set to 2 seconds.

  The determination unit 51 determines the situation based on information from the reception unit 47, the comparison unit 49, and the timer 50.

  The delay time calculation unit 53 calculates a delay time (a time when the document is delayed with respect to the reference time due to the slip) according to the determination of the determination unit 51.

  The roller retraction time determination unit 55 determines a retraction time for the calling roller 15 to retreat from the contact position K toward the standby position H based on the calculation result of the delay time calculation unit 53. Specifically, the withdrawal time of the calling roller 15 is determined to be later than the preset withdrawal time by a delay time.

  Based on the calculation result of the delay time calculation unit 53, the jam sensor arrival prediction time calculation unit 59 calculates a time that is predicted to be detected by the jam sensor 45 after receiving the paper feed signal. Specifically, the jam sensor arrival prediction time is a time from when a paper feed signal is received to when the original is detected by the jam sensor 45 (preset jam detection time) when the document is conveyed without slipping. Calculate by adding twice the delay time.

  The jam detection time changing unit 61 changes the jam detection time (time when it is determined that a jam has been detected) based on the result calculated by the jam sensor arrival prediction time calculation unit 59. Specifically, the jam detection timing is changed to be when the estimated jam sensor arrival time calculated by the jam sensor arrival prediction time calculation unit 59 has elapsed.

  The processing unit 57 executes processing according to the determination, determination, and change of the determination unit 51, the roller retraction time determination unit 55, and the jam detection time change unit 61.

  The transmission unit 63 transmits the processing content executed by the processing unit 57 to the solenoid 35 and the stepping motor 37.

  Jam detection in the control unit 39 will be described. If the jam sensor 45 does not change from the non-detection state to the detection state within a predetermined time (within 0.3 seconds) after the reception unit 47 receives the paper feed signal, the determination unit 51 determines that the jam has been detected. As described above, a determination time (jam detection time) is set in advance. Further, when the jam sensor 45 does not change from the detection state to the non-detection state within a predetermined time (within 0.3 seconds) after the jam sensor 45 detects the leading edge of the document, the determination unit 51 detects the jam. A judgment time (jam detection time) is set in advance so as to make a judgment. The jam detection information is transmitted to the operation unit 48 of the image forming apparatus main body and displayed on the display screen of the operation panel 12 (see FIG. 4).

  The operation of the automatic document feeder 3 according to the present embodiment will be described with reference to FIGS. The specific times and times shown below are based on the time when a paper feed signal is received from the operation unit 48. First, 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. At this time, the determination unit 51 determines whether or not the document set sensor 41 is in a detection state (S1). When it is determined that the document set sensor 41 is not in the detection state, the determination unit 51 repeats the same determination. If it is determined that the document set sensor 41 is in the detection state, it is determined whether the determination unit 51 has received a paper feed signal from the operation unit 48 (S2). If it is determined that the paper feed signal has not been received, the determination unit 51 repeats the same determination. If it is determined that the paper feed signal has been received, the processing unit 57 drives the stepping motor 37 (S3), starts rotating the calling roller 15, and energizes the solenoid 35 (S4). The contact operation of the roller 15 is started. At the same time, the document stopper moves to the retracted position. 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 leading edge of the document T reaches a position facing the document detection sensor 43, a detection signal is transmitted from the document detection sensor 43 to the reception unit 47, and the comparison unit 49 receives the paper feed signal and then detects the document detection sensor. The time until the document is detected by 43 (document transport time) is compared with the reference time (0.2 seconds). Here, the determination unit 51 determines whether or not the document conveyance time is longer than the reference time (S5). If it is determined that the document conveyance time is not longer than the reference time, the flow ends. When it is determined that the document conveyance time is longer than the reference time (for example, when the time from receipt of the paper feed signal until the document detection sensor 43 detects the document is 0.25 seconds), the delay time calculation unit 53 calculates the delay time (S6), the jam sensor arrival time calculation unit 59 calculates the jam sensor arrival time based on the delay time (0.05 seconds) (S7). Then, the jam detection time changing unit 61 changes the jam detection time so as to delay the delay time twice (0.1 second) from the preset determination time (0.3 second) (S8). Thereafter, the roller retraction timing determination unit 55 determines the retraction time of the calling roller 15 as a time (0.45 seconds) obtained by adding a delay time (0.05 seconds) to a preset retraction time (0.4 seconds). (S9) After that, when the retreat time comes, the processing unit 57 cuts off the energization to the solenoid 35 (S10). At this time, since the calling roller 15 is retracted later than a preset retracting time, it is possible to lengthen the time for which the calling roller 15 is in contact with the document T and to prevent the document T from being unfed. Here, the determination unit 51 determines whether or not the paper feeding is completed (S11). If it is determined that the paper feeding has been completed, the processing unit 57 stops driving the stepping motor 37 (S12), and the flow ends. If it is determined that the paper feeding is not completed, the processing unit 57 energizes the solenoid 35 (S13), the calling roller 15 is brought into contact with the upper surface of the next original, and directed toward the separation feeding unit 17. And send it out. Here, the determination unit 51 determines whether or not the roller retraction time (0.45 seconds) determined in S9 has come (S14). If it is determined that it is not the roller retraction time, the determination unit 51 repeats the same determination. If it is determined that it is time to retract the roller, the flow returns to S10.

  When the document T sent out by the calling roller 15 reaches the separation feeding unit 17, only the uppermost document is separated and the document is fed toward the image reading position 19.

  In the case of reading only the first image surface (single-sided mode), the document is read at the image reading position 19 and then passes through the second conveyance path B, and the switching claw 21 (FIG. 1 is guided to the switching claw 21) at the position indicated by the solid line and discharged to the discharge portion 23.

  In the case of reading both sides of a document (double-sided mode), the document is read through the first transport path A and image information is read at the image reading position 19 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. 1). 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 paper discharge roller 31, the second image surface is read at the image reading position 19, 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 9 to the image forming unit 7. In the image forming unit 7, an image of a document read by the image reading unit 5 is formed on a recording medium. The recording medium on which the image is formed is discharged to the paper discharge unit 11.

  The effect of this Embodiment is demonstrated. According to the present embodiment, for a document with a strong non-feeding tendency (the timing detected by the document detection sensor 43 is delayed), the call time is increased by increasing the time for which the control unit 39 contacts the call roller 15. Since the conveyance time by the roller 15 can be lengthened, non-feeding of the original in the original conveyance path from the original tray 13 to the separation / feed unit 17 can be prevented with a simple configuration in which no pressing means such as an oil damper is provided. Moreover, since the pressing force of the calling roller against the document is not increased by pressing means such as an oil damper, the documents do not come into close contact with each other when the plurality of documents T are fed out by the calling roller 15, It is possible to prevent the double feeding of documents in the separation feeding unit 17.

  The control unit 39 delays the retracting time of the calling roller 15 from a preset retracting time for a document with a strong non-feeding tendency, thereby automatically extending the time for the calling roller 15 to contact the document.

  By delaying the time when the control unit 39 determines that a jam has been detected before the jam sensor 45 changes from the non-detection state to the detection state for a document that has a strong non-feed tendency, it is a jam that is not originally a jam. Can be prevented from being erroneously detected.

  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 FIG. FIG. 5 is a flowchart showing the control of the automatic document feeder according to this embodiment. In the present embodiment, a roller rotation speed changing unit that changes the rotation speed of the calling roller 15 is provided in the control unit 39 instead of the roller retraction timing determination unit 55. Further, in the present embodiment, as shown in FIG. 5, S21 to S28 are the same as S1 to S8 (see FIG. 2) in the first embodiment, and S30 to S34 are in the first embodiment. This is the same as S10 to S14 (see FIG. 2). However, in S34, unlike S14, the determination unit 51 determines whether it is a preset retraction time of the calling roller 15.

  That is, in the processing unit 57, after the jam detection time changing unit changes the jam detection time (S28), the roller rotation speed changing unit increases (changes) the rotation speed of the calling roller 15 (S29), The moving speed of the paper belt 38 is the same. Thereafter, the energization to the solenoid is cut off (S30).

  According to the present embodiment, the control unit 39 increases the rotation speed of the calling roller 15 with respect to a document having a strong non-feed tendency, and the document conveyance speed is set to the moving speed of the sheet feeding belt 38 (separation feeding unit 17). The feeding speed from the calling roller 15 to the separation feeding section 17 can be made smooth and reliable, so that a simple configuration without a pressing means such as an oil damper can be used. Non-feed can be prevented.

  The control unit 39 sets the rotation speed of the calling roller 15 to be the same as the feeding speed of the separation feeding unit 17 with respect to a document having a strong non-feeding tendency. Since the difference from the moving speed of the paper feeding belt 38 (feeding speed of the separation feeding unit 17) can be minimized, it is possible to reliably prevent the unfed document.

  A third embodiment will be described with reference to FIG. FIG. 6 is a flowchart showing the control of the automatic document feeder according to the present embodiment.

  In the present embodiment, using the transmission type sensor or the ultrasonic sensor as the document detection sensor 43, the control unit 39 determines whether or not a plurality of documents T sent out by the calling roller 15 are overlapped, When it is determined that a plurality of documents T are overlapped, the retraction time of the calling roller 15 is changed. Note that the transmissive sensor can detect whether or not a plurality of documents T overlap each other based on the transmissive state. The ultrasonic sensor can detect whether or not a plurality of documents T overlap each other based on the ultrasonic waveform state.

  The control unit 39 is not provided with the comparison unit 49, the delay time calculation unit 53, the jam sensor arrival time calculation unit 59, and the jam detection time change unit 61. Is provided.

  In the present embodiment, as shown in FIG. 6, S41 to S44 are the same as S1 to S4 in the first embodiment, and S47 to S51 are the same as S10 to S14 in the first embodiment. ing.

  That is, after the processing unit 57 energizes the solenoid (S44), the determination unit 51 determines whether or not a plurality of documents T are overlapped (S45). If it is determined that a plurality of documents T do not overlap, the flow ends. When it is determined that a plurality of documents T overlap, the roller retraction time changing unit sets the retraction time of the calling roller 15 earlier than the preset retraction time (0.4 seconds) (0.35 seconds). (S46), the processing unit 57 cuts off the energization of the solenoid 35 early (S47).

  According to the present embodiment, when a plurality of overlapping originals T are sent out by the calling roller 15, the control unit 39 shortens the time for which the calling roller 15 contacts the original so that the calling roller 15 By shortening the document conveyance time and reducing the amount of the document pushed into the separating / feeding unit 17 side, it is possible to prevent the feeding of the document in the separating / feeding unit 17.

  When the controller 39 advances the retracting timing of the calling roller 15 for a plurality of stacked documents T, it is possible to automatically prevent the document feeding by the separation feeding unit 17.

  A fourth embodiment will be described with reference to FIG. FIG. 7 is a flowchart showing the control of the automatic document feeder according to the present embodiment.

  In the present embodiment, using the transmission type sensor or the ultrasonic sensor as the document detection sensor 43, the control unit 39 determines whether or not a plurality of documents T sent out by the calling roller 15 are overlapped, When it is determined that a plurality of originals T overlap, the rotation speed of the calling roller 15 is changed.

The control unit 39 is not provided with the comparison unit 49, the delay time calculation unit 53, the jam sensor arrival time calculation unit 59, and the jam detection timing change unit 61, and changes the roller rotation speed instead of the roller retraction time determination unit 55. Is provided.
In this embodiment, as shown in FIG. 7, S61 to S64 are the same as S1 to S4 in the first embodiment, and S67 to S71 are the same as S10 to S14 in the first embodiment. ing. However, in S71, unlike S14, the determination unit 51 determines whether it is a preset retraction time of the calling roller 15.

  That is, after the processing unit 57 energizes the solenoid (S64), the determination unit 51 determines whether or not a plurality of documents T overlap each other (S65). If it is determined that a plurality of documents T do not overlap, the flow ends. If it is determined that a plurality of documents T are stacked, the roller rotation speed changing unit changes the rotation speed of the calling roller 15 to be, for example, 10% to 20% smaller than the initial setting value (S66). The energization to the solenoid 35 is cut (S67).

  According to the present embodiment, when a plurality of overlapping originals T are sent out by the calling roller 15, the control unit 39 makes the rotational speed of the calling roller 15 smaller than a preset rotational speed, thereby By reducing the conveyance speed, it is possible to improve the effect of document separation in the document conveyance path from the document tray 13 to the separation feeding unit 17.

  The control unit 39 lowers the rotation speed of the calling roller 15 from a preset rotation speed with respect to a plurality of stacked documents T, whereby the document T is conveyed from the document tray 13 to the separation feeding unit 17. In the meantime, the effect of separating the original T can be enhanced, and the separation of the original in the separation feeding unit 17 can be improved.

  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.

  The calling roller 15 is moved between the standby position H and the contact position K by driving the solenoid 37. Instead, as shown in FIG. 8, an arm for holding the calling roller 15 is used. 69 and the motor 73 may be connected via a drive transmission member such as a cam, and the calling roller 15 may be moved between the standby position H and the contact position K by driving the motor 73. As shown in FIG. 8, the arm 69 may be rotated about the drive shaft of the drive roller 65 of the paper feed belt 38 as a fulcrum.

  As shown in FIG. 8, a separating member 71 for separating the document T may be provided in the document transport path between the document tray 13 and the separation feeding unit 17.

  The separation feeding unit 17 may include a sheet feeding roller and a separation pad that comes into contact with the sheet feeding roller from below. In this case, it is preferable that the separation pad is pivotally supported at one end and is constantly urged toward the sheet feeding roller by the coil spring at the other end. Thereby, the uppermost paper can be separated and fed from the document guided between the paper feed roller and the separation pad.

  In the first embodiment, when it is determined that a jam has been detected when there is no change in the detection signal of the jam sensor 45 for a predetermined time after the feeding of the document by the calling roller 15 is started, the feeding of the document is started. When the time from when the document detection sensor 43 detects the document to the document is longer than a predetermined reference time, the timing for determining that a jam has been detected is delayed from the preset determination timing. Or, in addition to this, when it is determined that a jam has been detected when there is no change in the detection signal of the jam sensor 45 for a predetermined time after the jam sensor 45 detects the leading edge of the document, the document feed is started. When the time until the document detection sensor 43 detects a document is longer than a predetermined reference time, a time for determining that a jam has been detected is set in advance. It may be delayed than the judgment time. Thereby, it is possible to prevent misdetection of a jam from when the jam sensor 45 is in a detection state to when it is in a non-detection state.

  In the second embodiment, the rotation speed of the calling roller 15 is set to be the same as the moving speed of the paper feeding belt 38 in S29 of FIG. The moving speed may be 1% to 4% smaller than the moving speed.

  In the above-described embodiment, the retracting timing of the calling roller 15 is set in advance 0.4 seconds after receiving the paper feed signal. However, the present invention is not limited to this. It may be set in advance 0.2 seconds after receipt.

  In the above-described embodiment, the jam detection timing is set in advance 0.3 seconds after receiving the paper feed signal. However, the present invention is not limited to this, and depending on the specifications of the apparatus, for example, after receiving the paper feed signal It may be set in advance after 0.25 seconds.

  In the first embodiment and the second embodiment, the jam sensor arrival time is calculated by adding twice the delay time to the preset jam detection time. It may be calculated by adding 1.5 times the delay time to the detected jam detection time.

  In the fourth embodiment, in S66, the rotation speed of the calling roller 15 is 10% to 20% smaller than the initial setting value. However, the present invention is not limited to this. For example, the rotation speed of the calling roller 15 is set to the initial setting value. 20% to 30% smaller than that.

1 is a longitudinal sectional view showing a schematic configuration of an automatic document feeder according to a first embodiment. 4 is a flowchart illustrating control of the automatic document feeder according to the first embodiment. FIG. 3 is a block diagram illustrating a control configuration of the automatic document feeder 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. 10 is a flowchart illustrating control of an automatic document feeder according to a third embodiment. 10 is a flowchart illustrating control of an automatic document feeder according to a fourth embodiment. FIG. 9 is a longitudinal sectional view showing a periphery of a document conveyance path from a document tray to a separation feeding unit of an automatic document conveyance device according to a modified example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 3 Automatic document feeder 13 Document tray 15 Calling roller 17 Separation feeding unit 19 Image reading position 39 Control unit 43 Document detection sensor 45 Jam sensor H Contact position K Standby position T Document

Claims (7)

Separation feeding is provided with a document tray on which a document is set, a calling roller for feeding the document set on the document tray, and a separation feeding unit for separating and feeding the documents sent by the calling roller one by one. An automatic document feeder that transports a document fed from a section to an image reading position and then ejects the document, wherein the calling roller is between a contact position that contacts the upper surface of the document and a standby position that is retracted from the contact position. It is movable, and a document detection sensor for detecting the document in the document transport path from the document tray until the separation feeding section, the movement or rotation speed of the ductor roller receives a detection signal from the original detecting sensor a control unit for controlling, by detecting the jamming of the document has a jam sensor for transmitting a detection signal to the control unit, in response to the detection signal of the original detection sensor, With serial ductor roller changes the rotational speed of the time or the ductor roller is in contact with the document, the time from receiving a document conveyance start signal to the original detection sensor detects the document than the predetermined reference time When it is determined that the length is longer, the retracting time of the calling roller is delayed from a preset retracting time, and the control unit detects a detection signal from the jam sensor for a predetermined time after receiving the document conveyance start signal. If there is no change in the jam, it is determined that a jam has been detected, and a jam occurs when the time from receipt of the document conveyance start signal until the document detection sensor detects the document is longer than a predetermined reference time. An automatic document feeder characterized by delaying the time at which it is determined that the image is detected from a predetermined time . Separation feeding is provided with a document tray on which a document is set, a calling roller for feeding the document set on the document tray, and a separation feeding unit for separating and feeding the documents sent by the calling roller one by one. An automatic document feeder that transports a document fed from a section to an image reading position and then ejects the document, wherein the calling roller is between a contact position that contacts the upper surface of the document and a standby position that is retracted from the contact position. A document detection sensor that detects a document in a document transport path from a document tray to the separation feeding unit, and controls the movement or rotation speed of the calling roller in response to a detection signal from the document detection sensor And a jam sensor for detecting a jam of the document and transmitting a detection signal to the control unit, the control unit according to a detection signal of the document detection sensor Fine out roller with changing the rotational speed of the time or the ductor roller is in contact with the document, the time from receiving a document conveyance start signal to the original detection sensor detects the document than the predetermined reference time If it is determined that the long, feeding speed and same west of the rotational speed of the ductor roller the separating and feeding part, and the control unit a predetermined time after receiving the document conveyance start signal from the jam sensor When the detection signal is unchanged, it is determined that a jam has been detected, and the time from when the document conveyance start signal is received until the document detection sensor detects the document is longer than a predetermined reference time , the automatic document feeder you wherein the delaying than the preset determination time when to determining that the detected jam. Separation feeding is provided with a document tray on which a document is set, a calling roller for feeding the document set on the document tray, and a separation feeding unit for separating and feeding the documents sent by the calling roller one by one. An automatic document feeder that transports a document fed from a section to an image reading position and then ejects the document, wherein the calling roller is between a contact position that contacts the upper surface of the document and a standby position that is retracted from the contact position. A document detection sensor that detects a document in a document transport path from the document tray to the separation feeding unit, and a movement signal or a rotation speed of the calling roller in response to a detection signal from the document detection sensor. A control unit for controlling, and a jam sensor for detecting a jam of a document and transmitting a detection signal to the control unit, the control unit according to a detection signal of the document detection sensor, With serial ductor roller changes the rotational speed of the time or the ductor roller is in contact with the document, the time from receiving a document conveyance start signal to the original detection sensor detects the document than the predetermined reference time If it is determined that the long, the delay than the predetermined retracted timing the evacuation time of the ductor roller, and the control unit, the jam sensor a predetermined time from the detection of the document, detects from the jam sensor When it is determined that a jam has been detected when there is no change in the signal, and the time from when the document conveyance start signal is received until the document detection sensor detects the document is longer than a predetermined reference time, automatic document feeder you wherein the delaying than the preset determination time when to determining that the detected jam. Separation feeding is provided with a document tray on which a document is set, a calling roller for feeding the document set on the document tray, and a separation feeding unit for separating and feeding the documents sent by the calling roller one by one. An automatic document feeder that transports a document fed from a section to an image reading position and then ejects the document, wherein the calling roller is between a contact position that contacts the upper surface of the document and a standby position that is retracted from the contact position. A document detection sensor that detects a document in a document transport path from the document tray to the separation feeding unit, and a movement signal or a rotation speed of the calling roller in response to a detection signal from the document detection sensor. A control unit for controlling, and a jam sensor for detecting a jam of a document and transmitting a detection signal to the control unit, the control unit according to a detection signal of the document detection sensor, The time during which the call roller is in contact with the document or the rotation speed of the call roller is changed, and the time from when the document conveyance start signal is received until the document detection sensor detects the document is longer than a predetermined reference time If it is determined that the length is longer, the rotation speed of the calling roller is the same as the feeding speed of the separation feeding unit, and the control unit detects the jam sensor for a predetermined time after the jam sensor detects the document. It is intended to determine that detects a jam if there is no change in the detection signal from the time after receiving the document conveyance start signal to the original detection sensor detects a document is longer than the predetermined reference time case, automatic document feeder you wherein the delaying than the preset determination time when to determining that the detected jam. A document tray on which the document is placed and a call to send the document placed on the document tray
Separation feeding that separates and feeds the documents sent by the roller and the calling roller one by one
An automatic original that discharges the document fed from the separation feeding unit after being transported to the image reading position.
The document conveying device, wherein the calling roller is movable between a contact position contacting the upper surface of the document and a standby position retracted from the contact position, and the document from the document tray to the separation feeding unit A document detection sensor for detecting a document in the conveyance path; and a control unit that receives a detection signal from the document detection sensor and controls the movement or rotation speed of the calling roller, and the control unit includes the document detection sensor In accordance with the detection signal, the time during which the calling roller is in contact with the document or the rotation speed of the calling roller is changed, and the document detection sensor can detect whether or not a plurality of documents overlap each other. a sensor or an ultrasonic sensor, wherein, when it is determined that the document is overlapped plurality hasten than the ductor roller preset retracted timing the evacuation time of this Automatic document feeder said. A document tray on which the document is placed and a call to send the document placed on the document tray
Separation feeding that separates and feeds the documents sent by the roller and the calling roller one by one
An automatic original that discharges the document fed from the separation feeding unit after being transported to the image reading position.
The document conveying device, wherein the calling roller is movable between a contact position contacting the upper surface of the document and a standby position retracted from the contact position, and the document from the document tray to the separation feeding unit A document detection sensor for detecting a document in the conveyance path; and a control unit that receives a detection signal from the document detection sensor and controls the movement or rotation speed of the calling roller, and the control unit includes the document detection sensor In accordance with the detection signal, the time during which the calling roller is in contact with the document or the rotation speed of the calling roller is changed, and the document detection sensor can detect whether or not a plurality of documents overlap each other. a sensor or an ultrasonic sensor, wherein, when it is determined that the document is overlapped plurality, be less than the rotational speed of the rotational speed preset of the ductor roller Automatic document feeder you wherein a. An automatic document feeder according to any one of claims 1 to 6 is provided, an image of a document conveyed to an image reading position is read by the automatic document feeder, and the read image is formed on a recording medium. An image forming apparatus .

Images