JP2016204115A - Manuscript conveyance device and image formation apparatus having the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manuscript conveyance device which can easily achieve desired ipm (the readable number for one minute).SOLUTION: A manuscript conveyance device is configured to start conveyance of a manuscript with a register roller for each prescribed time when consecutively conveying a plurality of manuscripts having a prescribed length in a conveyance direction, and starts to feed the next manuscript to a sheet feeding roller when the first time T1 has elapsed from the start of conveyance of the preceding manuscript with the register roller. The first time T1 is the time obtained by subtracting the time required by the manuscript to proceed between the sheet feeding roller and the register roller and the time for suspending the proceeding of the manuscript with the register roller from the prescribed time.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a document conveying device and an image forming apparatus including the same.

  An image forming apparatus having an image reading unit for reading a document may be provided with a document transport device for transporting the document to a document reading position. Such a document conveying device is disclosed in, for example, Patent Document 1.

  The document transport device of Patent Document 1 has a document transport path that connects a document set tray to a reading position. In the document transport path, a paper feed roller and a registration roller are provided in order from the upstream side in the transport direction (document set tray side). When the document transport operation is started, the paper feed roller feeds the document set on the document set tray to the document transport path. The registration roller temporarily stops the progress of the document in the transport direction, and then transports the document in the transport direction.

  In addition, a registration sensor having a detection position at a position upstream of the registration roller in the conveyance direction is provided in the document conveyance path. The registration sensor is turned on when there is a document at the detection position, and turned off when there is no document at the detection position. That is, the registration sensor is turned on when the leading edge of the document reaches the detection position, and turned off when the trailing edge of the document passes the detection position.

  In the document conveying device of Patent Document 1, when a plurality of documents are continuously conveyed, after the feeding of the preceding document is started, when it is detected that the trailing edge of the preceding document has passed through the detection position of the registration sensor, Based on the detection time, the start timing of feeding the next original is determined. Specifically, when the trailing edge of the preceding document passes through the detection position and the registration sensor changes from OFF to ON, feeding of the next document is started.

JP 2009-253984 A

  In the document conveying apparatus, the number of sheets of a predetermined size that can be read in one minute (referred to as ipm (images per minute)) is preset as apparatus specifications. As an example, when the number of documents of a predetermined size that can be read per minute is set to 60 (when 60 ipm is realized), the document must be conveyed to the reading position every second.

  For example, in a configuration in which the progress of the document is temporarily stopped by the registration roller, in order to realize 60 ipm, the conveyance of the document by the registration roller must be started at intervals of 1 second. That is, it is necessary to start feeding a document by the feed roller at intervals of 1 second.

  Here, it is assumed that a desired ipm can be realized by starting the conveyance of the document by the registration roller at predetermined time intervals. In addition, if feeding of the next document is started so that the distance between the papers, which is the distance between the trailing edge of the preceding document and the leading edge of the next document, becomes a predetermined paper distance, a predetermined time after the start of conveyance of the preceding document by the registration roller Assume that the conveyance of the next original by the registration roller can be started. In this case, in the configuration in which the feeding of the next original is started when the registration sensor is turned off when the trailing edge of the preceding document passes through the detection position of the registration sensor, the gap between the detection position of the registration roller and the detection position of the registration sensor is started. Whether or not the desired ipm can be realized is determined by the time required for the document to travel (hereinafter referred to as the registration sensor arrival time).

  Specifically, assuming that the time required for the document to travel a predetermined paper distance is the predetermined paper time, if the registration sensor arrival time is less than the predetermined paper time, the trailing edge of the preceding document is detected at the registration sensor detection position. By starting the feeding of the next original when the passage is detected, the distance between the preceding original and the next original can be made equal to or smaller than the predetermined distance. In other words, the next document can be transported by the registration roller within a predetermined time from the start of transport of the preceding document by the registration roller (a desired ipm can be realized).

  On the other hand, if the registration sensor arrival time exceeds the predetermined inter-sheet time, the feeding of the next document is started after the trailing edge of the preceding document is detected at the detection position of the registration sensor. The inter-paper distance exceeds a predetermined inter-paper distance. Therefore, the time from the start of conveyance of the preceding document by the registration roller to the start of conveyance of the next document by the registration roller exceeds a predetermined time (a desired ipm cannot be realized). In this case, in order to realize the desired ipm, the structure of the document conveying device itself must be changed (for example, the arrangement position of the registration roller and the registration sensor, or the conveyance path of the document is changed). ). Therefore, it leads to a cost increase.

  SUMMARY An advantage of some aspects of the invention is that it provides a document conveying device that can easily achieve a desired ipm and an image forming apparatus including the document conveying device.

  In order to achieve the above object, an original conveying apparatus of the present invention includes a paper feeding roller that feeds an original to an original conveying path, and a document that is disposed downstream of the paper feeding roller in the conveying direction and that travels along the original conveying path. The detection position is the position between the registration roller for stopping the progress and correcting the skew of the document, and the position between the paper feed roller and the registration roller in the document transport path, and the output value according to the presence or absence of the document at the detection position. And a control unit that controls the driving of the paper feeding roller and the registration roller, as well as detecting the arrival of the leading edge of the document at the detection position and the passage of the trailing edge based on the output value of the registration sensor. When a plurality of documents having a predetermined length in the transport direction are transported continuously, it is determined that the transport of the documents by the registration rollers is started every predetermined time. To have. The control unit detects that the leading edge of the preceding document has reached the detection position, and then temporarily stops the progress of the document by the registration roller during the time required for the document to travel between the detection position and the registration roller. When the time for adding the time to pass has elapsed, the conveyance of the preceding document by the registration roller is started, and when the first time has elapsed from the start of conveyance of the preceding document by the registration roller, the feeding of the next document to the feeding roller is started. Let it begin. Note that the first time is a positive value, and the time required for the document to travel between the paper feed roller and the registration roller and the time for temporarily stopping the progress of the document by the registration roller are subtracted from the predetermined time. It was time.

  In the configuration of the present invention, when the first time has elapsed from the start of conveyance of the preceding document by the registration roller, the feeding roller starts feeding the next document, so that a predetermined time has elapsed from the start of conveyance of the preceding document by the registration roller. When the time has elapsed, the leading edge of the next original has already reached the registration roller (the state where the progress of the next original has been temporarily stopped by the registration roller). Thereby, when a predetermined time elapses from the start of the conveyance of the preceding document by the registration roller, the conveyance of the next document by the registration roller can be started (a desired ipm can be realized).

  Note that the configuration of the present invention does not employ the method of measuring the feeding start timing of the next document based on the passage time of the trailing edge of the preceding document at the detection position of the registration sensor, as in the prior art. Accordingly, even when the registration sensor arrival time exceeds the predetermined inter-sheet time, the conveyance of the next original by the registration roller can be started when a predetermined time has elapsed from the start of the conveyance of the preceding original by the registration roller.

  As described above, according to the present invention, a desired ipm can be easily realized.

1 is a schematic diagram of an image forming apparatus including a document conveying device according to an embodiment of the present invention. 1 is a schematic diagram of an original conveying apparatus according to an embodiment of the present invention. 1 is a diagram illustrating an example of a hardware configuration of an image forming apparatus including a document conveying device according to an embodiment of the present invention. 1 is a diagram illustrating an example of a hardware configuration of an original conveying apparatus according to an embodiment of the present invention. The figure for demonstrating the behavior of the actuator used as the detection target of the registration sensor installed in the original conveying apparatus by one Embodiment of this invention. The figure for demonstrating the behavior of the actuator used as the detection target of the registration sensor installed in the original conveying apparatus by one Embodiment of this invention. The figure for demonstrating the behavior of the actuator used as the detection target of the registration sensor installed in the original conveying apparatus by one Embodiment of this invention. FIG. 4 is a timing chart for explaining a sheet feeding start timing when feeding a document in the document conveying device according to the embodiment of the present invention. FIG. 4 is a timing chart for explaining a sheet feeding start timing when feeding a document in the document conveying device according to the embodiment of the present invention. FIG. 4 is a timing chart for explaining a sheet feeding start timing when feeding a document in the document conveying device according to the embodiment of the present invention. Timing chart for explaining conventional document feed start timing Timing chart for explaining conventional document feed start timing 6 is a flowchart for explaining a flow of control when a document is fed in the document conveying device according to the embodiment of the present invention.

  An embodiment of the present invention will be described by taking an image forming apparatus (multifunction machine) capable of executing a plurality of types of jobs such as a print job and a scan job as an example.

<Overall configuration of image forming apparatus>
As illustrated in FIG. 1, the image forming apparatus 100 according to the present exemplary embodiment includes an operation panel 101, an image reading unit 102, a paper feeding unit 103, a paper transporting unit 104, an image forming unit 105, and a fixing unit 106. A document conveying device 200 for conveying the document D is installed above the image forming apparatus 100 (above the image reading unit 102).

  The operation panel 101 includes a liquid crystal display unit 11 disposed on the front side of the apparatus and having a display surface covered with a touch panel. The liquid crystal display unit 11 displays a message indicating the device status, soft keys for receiving various inputs, and the like. The operation panel 101 is also provided with hard keys such as a numeric keypad 12 and a start key 13.

  The image reading unit 102 reads (scans) one side of the document D to generate image data. Although not shown, the image reading unit 102 is provided with optical system members such as an exposure lamp, a mirror, a lens, and an image sensor. Then, the image reading unit 102 irradiates the document D placed on the contact glass 20a with light by the user, and A / D converts the output value of the image sensor that receives the reflected light from the document D. , Generate image data. Alternatively, the image reading unit 102 irradiates light on the document D conveyed on the contact glass 20b by the document conveying device 200, and A / D converts the output value of the image sensor that receives the reflected light from the document D. Thus, image data is generated. Accordingly, printing can be performed based on the image data obtained by scanning the document D by the image reading unit 102, and the image data obtained by scanning can be accumulated.

  The paper feed unit 103 has a cassette 31 that stores paper P, and supplies the paper P in the cassette 31 to the paper transport path. The paper feeding unit 103 is provided with a pickup roller 32 for pulling out the paper P in the cassette 31 one by one. Further, the paper feeding unit 103 is provided with a pair of paper feeding rollers 33 for supplying the paper P to the paper transport path while suppressing the double feeding of the paper P drawn from the cassette 31. The paper feed roller pair 33 includes a paper feed roller located on the upper side and a separation roller located on the lower side.

  The paper transport unit 104 transports the paper P along the paper transport path and finally guides it to the paper discharge tray 41. The paper transport unit 104 includes a plurality of transport roller pairs 42 that are rotatably installed in the paper transport path. Further, the paper transport unit 104 includes a registration roller pair 43 installed at a position upstream of the image forming unit 105 in the paper transport direction (a position immediately before reaching the image forming apparatus 105). The registration roller pair 43 causes the paper P to stand by immediately before the image forming unit 105, and sends the paper P to the image forming unit 105 at a timing.

  The image forming unit 105 forms a toner image based on the image data, and transfers the toner image onto the paper P. The image forming unit 105 includes a photosensitive drum 51, a charging device 52, an exposure device 53, a developing device 54, a transfer roller 55, and a cleaning device 56.

  When forming an image, first, the photosensitive drum 51 is rotationally driven, and the charging device 52 charges the surface of the photosensitive drum 51 to a predetermined potential. The exposure device 53 outputs a light beam L based on the image data, and scans and exposes the surface of the photosensitive drum 51. As a result, an electrostatic latent image is formed on the surface of the photosensitive drum 51. The developing device 54 develops toner by supplying toner to the electrostatic latent image formed on the surface of the photosensitive drum 51.

  The transfer roller 55 can rotate while being pressed against the surface of the photosensitive drum 51. Then, the registration roller pair 43 measures the timing and causes the paper P to enter between the transfer roller 55 and the photosensitive drum 51. At this time, a transfer voltage is applied to the transfer roller 55. As a result, the toner image on the surface of the photosensitive drum 51 is transferred to the paper P. Thereafter, the cleaning device 56 removes the toner remaining on the surface of the photosensitive drum 51.

  The fixing unit 106 heats and presses the toner image transferred onto the paper P to fix it. The fixing unit 106 includes a heating roller 61 and a pressure roller 62. The heating roller 61 incorporates a heater 63. The pressure roller 62 is in pressure contact with the heating roller 61. The paper P on which the toner image is transferred is heated and pressurized by passing between the heating roller 61 and the pressure roller 62. As a result, the toner image is fixed on the paper P and printing is completed. Thereafter, the printed paper P is sent to the paper discharge tray 41 by the transport roller pair 42.

<Configuration of document feeder>
As shown in FIG. 2, the document conveying device 200 supplies the document D set on the document setting tray 21 to the document conveying path 22, conveys the document D along the document conveying path 22, and finally the document. It discharges to the discharge tray 23. A position in the middle of the document conveyance path 22 is a reading position RP (position facing the contact glass 20b) of the document D. When the document D is transported to the reading position RP, the image reading unit 102 reads the document D. Is read (a surface directed upward when the document set tray 21 is set). In FIG. 2, the conveyance direction of the document D is indicated by a dotted arrow.

  In the document transport path 22, a paper feed unit 24 (including a pickup roller 25 and a paper feed roller 26), a registration roller pair 27, a transport roller pair 28, and a paper discharge roller pair 29 are from the upstream side (the document set tray 21 side). They are provided in this order toward the downstream side (the document discharge tray 23 side). The registration roller pair 27 corresponds to a “registration roller”.

  The paper feeding unit 24 pulls out the original D set on the original setting tray 21 and feeds it to the original conveying path 22, and sends the original D from the upstream side to the downstream side of the original conveying path 22 (feeding operation). I do. The paper feed unit 24 feeds the document D drawn from the document set tray 21 to the document transport path 22 and the upstream side of the document transport path 22 by picking up the document D set on the document set tray 21. And a paper feed roller 26 that feeds from the side to the downstream side.

  The pickup roller 25 and the paper feed roller 26 are connected to each other via a gear (not shown). Further, a driving force is transmitted from the sheet feeding motor M1 (see FIG. 4) to the roller shafts of the pickup roller 25 and the sheet feeding roller 26. The paper feed motor M1 rotates forward when a job involving conveyance of the document D is executed. As a result, the pickup roller 25 and the paper feed roller 26 rotate in a direction to feed the document D from the upstream side to the downstream side of the document transport path 22.

  When the paper feed motor M1 rotates forward, the pickup roller 25 moves (lowers) in the direction of the solid line arrow in FIG. 2 while rotating. As a result, the pickup roller 25 comes into contact with the document D set on the document set tray 21, so that the document D is pulled out from the document set tray 21. The pickup roller 25 and the paper feed roller 26 stop rotating when feeding the preceding document D and then rotate to feed the next document D when continuously feeding a plurality of documents D. To resume.

  For example, each roller shaft of the pickup roller 25 and the paper feed roller 26 is provided with a clutch (not shown) for transmitting the driving force from the paper feed motor M1. The rotations of the pickup roller 25 and the paper feed roller 26 are stopped when the transmission of the driving force from the paper feed motor M1 is interrupted by the clutch.

  When the job involving the conveyance of the document D is completed, the paper feed motor M1 rotates in the reverse direction and the pickup roller 25 is raised. That is, there is a gap between the pickup roller 25 and the document setting tray 21. As a result, a new document D can be set on the document set tray 21.

  Further, a separation pad 26 a is provided at a position facing the paper feed roller 26 across the transport path of the document D. The separation pad 26a is used to separate a plurality of originals D one by one when a plurality of originals D overlap. Specifically, when a plurality of documents D are fed to the nip (sheet feeding nip) between the sheet feeding roller 26 and the separation pad 26a, the upper layer document D (the document D to be conveyed at this time) is By abutting on the pickup roller 26, it proceeds in the transport direction as it is. On the other hand, the lower layer original D contacts the separation pad 26 a but does not contact the paper feed roller 26. As a result, the lower layer original D remains in the paper feed nip.

  The registration roller pair 27 temporarily stops the progress of the document D from the upstream side to the downstream side of the document transport path 22 and bends the document D to correct skew. That is, the registration roller pair 27 does not rotate when the leading edge of the document D reaches the nip (registration nip), and rotates when a predetermined stop time elapses after the leading edge of the document D reaches ( The conveyance by the registration roller pair 27 is started). For example, in this configuration, a stop time (correction time for correcting skew) is temporarily set to 5 ms for temporarily stopping the progress of the document D whose leading edge has reached the registration roller pair 27. As a result, the document D that has reached the registration roller pair 27 is conveyed to the reading position RP in a state where the skew is corrected. The registration roller pair 27 is driven by a registration motor M2 (see FIG. 4).

  The conveyance roller pair 28 and the discharge roller pair 29 convey the document D sent from the reading position RP and discharge it to the document discharge tray 23. The transport roller pair 28 and the paper discharge roller pair 29 are driven by a transport motor M3 (see FIG. 4).

  Further, the document conveying apparatus 200 is provided with a registration sensor RS. The registration sensor RS is a transmissive optical sensor having a light emitting portion and a light receiving portion, and is a position between the paper feed roller 26 and the registration roller pair 27 in the document transport path 22 (hereinafter referred to as a detection position DP). The output value is changed according to the presence or absence of the document D in FIG. That is, based on the output value of the registration sensor RS, it is possible to detect the leading edge arrival and the trailing edge passage of the document D at the detection position DP. Details will be described later.

<Hardware Configurations of Image Forming Apparatus and Document Conveying Apparatus>
As shown in FIG. 3, the image forming apparatus 100 includes a main control unit 110 that controls the entire apparatus. The main control unit 110 includes a CPU 111, an image processing unit 112, and a storage unit 113. The image processing unit 112 includes an ASIC dedicated to image processing, a memory, and the like, and performs various types of image processing (enlargement / reduction, density conversion, data format conversion, etc.) on the image data. The storage unit 113 includes a ROM, a RAM, and the like. For example, a program and data necessary for job execution are stored in the ROM, and the program and data are expanded in the RAM.

  The operation panel 101, the image reading unit 102, the sheet feeding unit 103, the sheet conveying unit 104, the image forming unit 105, and the fixing unit 106 are connected to the main control unit 110 and operate based on instructions from the main control unit 110. Further, main controller 110 is connected to document feeder 200.

  As shown in FIG. 4, the document conveyance device 200 includes a document conveyance control unit 210 connected to the main control unit 110. The document conveyance control unit 210 corresponds to a “control unit”. The document conveyance control unit 210 includes a CPU 211 and a storage unit 212. The document conveyance control unit 210 receives an instruction from the main control unit 110 and controls the document conveyance operation of the document conveyance device 200. Specifically, the document conveyance control unit 210 controls driving of the paper feed motor M1, the registration motor M2, and the conveyance motor M3, and rotates various rollers or stops the rotation.

<Detection by resist sensor>
As shown in FIG. 5A, the actuator 30 is rotatably installed at the detection position DP (position on the downstream side in the conveyance direction of the registration roller pair 27) of the document conveyance path 22. The actuator 30 can be rotated in one direction (A direction) and the other direction (B direction) opposite to the one direction with the rotation shaft 30a as a fulcrum. In addition, the actuator 30 has a portion 30 b that protrudes inside the document conveyance path 22. The portion 30b of the actuator 30 is a portion that comes into contact with the document D that has reached the detection position DP. And the part 30c on the opposite side to the part 30b among the actuators 30 becomes a detection target of the registration sensor RS. In the following description, the portion 30b is referred to as a contact portion 30b, and the portion 30c is referred to as a detected portion 30c.

  When there is no document D at the detection position DP, the actuator 30 is held at the position shown in FIG. 5A (hereinafter referred to as the reference position). When the leading edge of the document D reaches the detection position DP, as shown in FIG. 5B, the contact portion 30b is pushed by the document D, and the actuator 30 is rotated by a certain amount in the A direction. The actuator 30 is held at a position (hereinafter referred to as a predetermined position) rotated by a certain amount from the reference position in the A direction when the document D passes through the detection position DP. Thereafter, when the trailing edge of the document D has completely passed the detection position DP, as shown in FIG. 5C, the contact of the document D with the contact portion 30b is released, so that the actuator 30 rotates in the B direction. Thereby, the actuator 30 returns to the reference position, and the state shown in FIG. 5A is obtained. The reference position corresponds to the “first position”, and the predetermined position corresponds to the “second position”.

  Here, when the position of the optical path (detection region) between the light emitting portion and the light receiving portion of the registration sensor RS is within the range determined as the reference position, the detected portion 30c is the registration sensor. The detection part 30c is set to be out of the detection area of the registration sensor RS when the detection area of the RS is shielded and the actuator 30 is rotated in the A direction from the reference position. Therefore, the registration sensor RS changes the output value depending on whether or not the document D is present at the detection position DP. That is, the registration sensor RS outputs a value indicating the presence of the document D when the actuator 30 is rotated in the A direction from the reference position, while the document 30 is in a state where the actuator 30 is within the range defined as the reference position. A value indicating the absence of D is output.

  Since the actuator 30 is rotatably installed, the actuator 30 does not stop immediately after being rotated from the predetermined position to the reference position because the trailing edge of the document D has passed the detection position DP (defined as the reference position). Does not stop in range). That is, after the actuator 30 rotates from the predetermined position to the reference position (after the registration sensor RS outputs a value indicating the absence of the document D), the registration sensor RS stably outputs a value indicating the absence of the document D. It takes some time to complete. The time required for the actuator 30 to stop within the range defined as the reference position after the actuator 30 is rotated from the predetermined position to the reference position can be experimentally determined, for example, 100 ms.

  When the time required for the actuator 30 rotated from the predetermined position to the reference position to stop within the range defined as the reference position is 100 ms, the conveyance distance corresponding to 100 ms (if the linear velocity is 410 mm / S, the conveyance is performed). When the document D is continuously conveyed at an interval smaller than the distance (41 mm), after the trailing edge of the preceding document D passes the detection position DP, before the above-described time has elapsed (the output value of the registration sensor RS is stabilized). Previously, the leading edge of the next original D reaches the detection position DP. In order to suppress the occurrence of such inconvenience, the minimum distance between sheets (corresponding to “predetermined distance between sheets”) is within a range in which the actuator 30 rotated from the predetermined position to the reference position is set as the reference position. It is the time required to stop. In this configuration, the minimum inter-paper distance is 41 mm. Hereinafter, the time required for the document D to travel through the minimum distance between the sheets may be referred to as the minimum sheet interval time (corresponding to “predetermined sheet interval time”).

  The output value of the registration sensor RS is input to the document conveyance control unit 210 (see FIG. 4). As a result, the document conveyance control unit 210 detects whether or not the document D exists at the detection position DP (the leading end of the document D and the passage of the trailing end).

<Document feed start timing>
Hereinafter, the timing for starting the feeding of the document D from the document set tray 21 to the document transport path 22 will be described. In the following description, the distance of the conveyance path from the paper feed roller 26 (paper feed nip) to the registration roller pair 27 (registration nip) is 127 mm, and the conveyance path from the detection position DP of the registration sensor RS to the registration roller pair 27 is assumed. The distance is 7 mm. Further, the linear velocity is set to 410 mm / s.

  Further, in the following description, as a specification of the document conveying device 200, when a plurality of A4 size documents D are conveyed continuously in the vertical direction (that is, a plurality of documents D having a length of 297 mm in the conveying direction are consecutive). Suppose that the registration roller pair 27 starts to convey the document D to the reading position RP every 1000 ms (corresponding to “predetermined time”). That is, the target ipm is 60 ipm. Hereinafter, the predetermined time may be referred to as a predetermined time T.

  As shown in FIG. 6, the leading edge of the preceding document D reaches the detection position DP after the feeding of the preceding document D to the document transport path 22 by the feeding roller 26 (rotation of the feeding roller 26) is started. Then, the registration sensor RS is turned on (the registration sensor RS outputs a value indicating the presence of the document D). Thereby, the document conveyance control unit 210 detects that the leading edge of the preceding document D has reached the detection position DP.

  The document D whose leading edge has reached the detection position DP reaches the registration roller pair 27 when 17 ms has elapsed since the leading edge has reached the detection position DP. Therefore, after the document conveyance control unit 210 detects the arrival of the leading document D at the detection position DP, until the time (22 ms) obtained by adding 17 ms to the time for correcting skew (5 ms) has elapsed. The paper feed roller 26 is continuously rotated. Then, at time P1 when 22 ms has elapsed since the registration sensor RS was turned on, the document conveyance control unit 210 stops the rotation of the paper feed roller 26 and conveys the preceding document D by the registration roller pair 27 (the registration roller pair 27 Rotation).

  However, when the preceding document D is the first sheet, the image reading unit 102 may not complete the preparation for reading the document D even at the time point P1. In this case, the conveyance of the preceding document D by the registration roller pair 27 is started after the reading preparation is completed. In the following description, it is assumed that the reading preparation of the image reading unit 102 has already been completed at the time point P1.

  Further, at the time point P1 when the conveyance of the preceding document D by the registration roller pair 27 is started (the time point P1 when the rotation of the paper feed roller 26 is stopped), the rear end side of the preceding document D is upstream in the conveyance direction of the paper feed roller 26. Remain on the side. For this reason, the paper feed roller 26 (pickup roller 25) rotates following the preceding document D traveling in the transport direction. The driven rotation of the paper feed roller 26 (pickup roller 25) continues until the trailing edge of the preceding document D passes through the paper feed nip.

  Therefore, when the trailing edge of the preceding document D passes through the pickup roller 25, the pickup roller 25 comes into contact with the next document D in a driven rotation state. As a result, the next original D is moved downstream in the transport direction in a state where the rear end portion of the previous original D and the leading end portion of the next original D overlap (the next original D continues to the previous original D and is downstream in the transport direction). To the side). In this state, the leading edge of the next original D reaches the paper feed nip. At this time, since the preceding document D exists on the next document D, the next document D contacts only the separation pad 26a (not contacts the paper feed roller 26). When the trailing edge of the preceding document D passes through the paper feed roller 26, the driven rotation of the paper feed roller 26 is stopped. As a result, the next original D remains in a state where the leading edge reaches the paper feed nip.

  As a result, in the feeding of the second and subsequent originals D, when the time (293 ms) required for the original D to travel between the paper supply roller 26 and the detection position DP has elapsed since the start of paper supply, the registration sensor RS turns on. In this case, the point of time 315 ms after the start of sheet feeding is the rotation stopping point P1 of the sheet feeding roller 26 (the rotation starting point P1 of the registration roller pair 27).

  On the other hand, when feeding the first document D, the leading end position of the document D at the start of feeding is a position upstream of the feeding nip in the transport direction. For this reason, in the feeding of the first document D, the time from the start of feeding until the registration sensor RS is turned on is longer than the feeding of the second and subsequent documents D (315 ms from the start of feeding). When the above time has elapsed, the rotation of the paper feed roller 26 is stopped).

  Here, as a conventional method of taking the paper feed start timing, there is a method (first conventional method) in which the feeding of the next original D is started when the trailing edge of the preceding original D passes the detection position DP. However, when the first conventional method is applied in the configuration of the present embodiment, the conveyance of the document D by the registration roller pair 27 cannot be started every 1000 ms (details will be described later). Therefore, in the present embodiment, the feeding of the next document D is started before the trailing edge of the preceding document D passes the detection position DP.

  Specifically, the document conveyance control unit 210 measures time from the start of conveyance of the preceding document D by the registration roller pair 27. Then, when the first time T1 has elapsed from the start of transport of the preceding document D by the registration roller pair 27 (time point P2), the document transport control unit 210 feeds the next document D to the paper feed roller 26 (pre-feed). To start. Here, the first time T1 is the time required for the document D to travel between the paper feed roller 26 (paper feed nip) and the registration roller pair 27 (registration nip) from the predetermined time T, and the registration roller pair 27. Is a time obtained by subtracting a stop time (correction time for correcting skew) from temporarily stopping the progress of the document D. That is, the first time T1 is 1000 ms-310 ms-5 ms = 685 ms. In this case, the conveyance start time P2 of the next original D is before the trailing edge passage time P3 of the preceding original D at the detection position DP.

  When the feeding of the next original D is started at the time point P2 when the first time T1 has elapsed from the start of the conveyance of the preceding original D by the registration roller pair 27, the conveyance start time P1 of the preceding original D by the registration roller pair 27 (that is, the paper supply) At the time P4 when 978 ms elapses from the feeding end time P1 of the preceding document D by the roller 26, the leading edge of the next document D reaches the detection position DP (the registration sensor RS is turned on). It should be noted that the document conveyance control unit 210, after a predetermined time has elapsed from the time point P3 at which the trailing end of the preceding document D is detected at the detection position DP (before the leading edge of the next document D reaches the registration roller pair 27), the registration roller. The rotation of the pair 27 is stopped.

  When 17 ms elapses after the leading edge of the next original D reaches the detection position DP, the leading edge of the next original D reaches the registration roller pair 27. Then, after the leading edge of the next original D reaches the registration roller pair 27, the original conveyance control unit 210 performs the next original D by the registration roller pair 27 at a time point P5 when a time (5 ms) for correcting skew has elapsed. Start transporting. As a result, the conveyance of the document D by the registration roller pair 27 is started every predetermined time T (1000 ms).

  If the feeding of the next original D is started at the time point P2 when the first time T1 (685 ms) has elapsed from the start of the conveyance of the preceding original D by the registration roller pair 27, the length in the conveyance direction of the original D to be conveyed is If it is 367 mm or less, the conveyance of the document D by the registration roller pair 27 can be started every predetermined time T (1000 ms). That is, when the A4 size original D is continuously conveyed vertically (when the original D having a length of 297 mm in the conveyance direction is continuously conveyed), as shown in FIG. The time from the start of transport of D to the start of transport of the next original D is a predetermined time T (1000 ms).

  If the length of the document D to be transported in the transport direction is 367 mm, as shown in FIG. 7, the preceding document is reached at time P13 when 878 ms has elapsed from the start of transport of the preceding document D by the registration roller pair 27. The rear end of D passes through the detection position DP. That is, the trailing edge passage time P13 of the preceding document D at the detection position DP is 171 ms later than the trailing edge passage time P3 of the preceding document D at the detection position DP shown in FIG.

  In this case, when feeding of the next document D is started at time P2 when the first time T1 (685 ms) has elapsed from the start of transport of the preceding document D by the registration roller pair 27, at the time P13, the upstream side in the transport direction from the detection position DP. The leading edge of the next original D has reached a position 41 mm back (a position advanced 79 mm downstream from the paper feed roller 26 in the conveyance direction). That is, at the time point P13, the distance between the preceding document D and the next document D is the minimum sheet distance (41 mm). Therefore, the feeding of the next original D can be continued as it is after time P13. As a result, as in the case of transporting the A4 size document D (see FIG. 6), the transport of the document D by the registration roller pair 27 can be started every predetermined time T (1000 ms).

  Here, the size of the document D to be transported varies, and the length of the document D to be transported in the transport direction may be 367 mm or less, or may exceed 367 mm. If the length of the document D to be transported in the transport direction is 368 mm, the next document D is fed when the first time T1 (685 ms) has elapsed from the start of transport of the preceding document D by the registration roller pair 27. Is started, the distance between the preceding document D and the next document D is 40 mm, which is smaller than the minimum distance (41 mm). For this reason, the leading edge of the next original D reaches the detection position D before the minimum sheet interval time (100 ms) elapses after the trailing edge of the preceding original D passes the detection position DP. For example, when the A3 size document D is continuously conveyed in the vertical direction (when the length of the conveyance target document D in the conveyance direction is 420 mm), before the trailing edge of the preceding document D passes the detection position DP. The leading edge of the next original D reaches the detection position DP. That is, the trailing edge of the preceding document D and the leading edge of the next document D overlap each other and pass through the detection position DP, and the registration sensor RS does not turn off.

  In order to eliminate such inconvenience, the document conveyance control unit 210 determines whether or not there is a preceding document D at the detection position DP when the second time T2 has elapsed from the start of feeding the next document D by the feed roller 26. (Hereinafter, the time when this determination is made is referred to as a determination time JP). Here, the second time T2 is a time obtained by subtracting the minimum paper interval time from the time required for the document D to travel between the paper supply roller 26 (paper supply nip) and the detection position DP. That is, the second time T2 is 293 ms-100 ms = 193 ms.

  If it is detected at the determination point JP that there is no preceding document D at the detection position DP (if the registration sensor RS is off), the document conveyance control unit 210 continues feeding the next document D. Let On the other hand, if it is detected that the preceding document D is present at the detection position DP at the determination time point JP (if the registration sensor RS is on), the document conveyance control unit 210 feeds the next document D. Stop it once. When the feeding of the next document D is temporarily stopped, the document transport control unit 210 detects that there is no document D at the detection position DP, and then resumes feeding the next document D.

  For example, in the timing charts shown in FIGS. 6 and 7, the trailing edge of the preceding document D has already passed the detection position DP at the determination time point JP (the registration sensor RS is off). For this reason, the feeding of the next original D is continued.

  On the other hand, when the length of the document D to be transported in the transport direction exceeds 367 mm, the feeding of the next document D is temporarily stopped at the determination point JP as shown in FIG. Hereinafter, a case where A3-size original D is continuously conveyed in the vertical direction (when the length in the conveyance direction of the original D to be conveyed is 420 mm) will be described as an example.

  As shown in FIG. 8, when the A3-size document D is continuously conveyed in the vertical direction, as in the timing charts shown in FIGS. 6 and 7, at the time P21 when 22 ms elapses after the registration sensor RS is turned on. Then, the rotation of the paper feed roller 26 is stopped, and the conveyance of the preceding document D by the registration roller pair 27 (the rotation of the registration roller pair 27) is started. In addition, at the time point P22 when the first time T1 has elapsed from the start of conveyance of the preceding document D by the registration roller pair 27, the feeding (pre-feeding) of the next document D by the sheet feeding roller 26 is started.

  After the feeding of the next original D by the paper feeding roller 26 is started, the original transport control unit 210 has passed the second time T2 from the start of feeding the next original D by the paper feeding roller 26 (determination time JP). Then, the presence or absence of the document D at the detection position DP is determined. Here, when the document D to be transported is A3 size, the trailing edge of the preceding document D passes through the detection position DP at a time P23 when 1007 ms has elapsed from the start of transport of the preceding document D by the registration roller pair 27. Therefore, at the determination time JP, the preceding document D remains at the detection position DP. Therefore, the document conveyance control unit 210 detects that the document D exists at the detection position DP. In this case, the document conveyance control unit 210 temporarily stops the feeding of the next document D by the feeding roller 26 (stops the rotation of the feeding roller 26).

  After temporarily stopping the feeding of the next original D by the paper supply roller 26, when the passage of the trailing edge of the preceding original D is detected at the detection position DP (time point P23), the original conveyance control unit 210 uses the paper supply roller 26. The feeding of the next original D is resumed (the paper feeding roller 26 is rotated). That is, the resumption of feeding of the next document D is performed when the distance between the preceding document D and the next document D becomes the minimum sheet distance (41 mm). As a result, when 100 ms has elapsed after the trailing edge of the preceding document D has passed the detection position DP (time point P24), the leading edge of the next document D reaches the detection position DP (the registration sensor RS is turned on). The document conveyance control unit 210 stops the rotation of the registration roller pair 27 after a predetermined time has elapsed from the time point P23 at which the passage of the trailing edge of the preceding document D is detected at the detection position DP.

  When 17 ms elapses from the point P24 when the leading edge of the next original D reaches the detection position DP, the leading edge of the next original D reaches the registration roller pair 27. Thereafter, the document conveyance control unit 210 starts conveyance of the next document D by the registration roller pair 27 at a time P25 when a time (5 ms) for correcting skew is elapsed.

  If the length of the document D to be transported exceeds 367 mm, the feeding of the next document D is temporarily stopped at the timing shown in FIG. 8, and then the trailing edge of the preceding document D is detected at the detection position DP. By restarting the feeding of the next original D at the timing of passing through, it is possible to suppress the inter-paper distance between the preceding original D and the next original D from being less than the minimum inter-paper distance. However, since the feeding of the next original D is temporarily stopped, the time from the start of conveyance of the preceding original D by the registration roller pair 27 to the start of conveyance of the next original D becomes longer than the predetermined time T (1000 ms). When the A3 size document D is conveyed (see FIG. 8), the time from the conveyance start of the preceding document D by the registration roller pair 27 to the conveyance start of the next document D is 1129 ms.

  A document size detection mechanism for detecting the size (length in the transport direction) of the document D set on the document set tray 21 may be installed in the document transport apparatus 200. In this case, based on the size of the preceding document D, the time required from the start of conveyance of the preceding document D by the registration roller pair 27 until the trailing edge of the preceding document D passes the paper feed roller 26 is obtained in advance. I can leave. Accordingly, after the trailing edge of the preceding document D passes the paper feed roller 26, the feeding of the next document D is started at the timing when the distance between the preceding document D and the next document D becomes the minimum sheet distance. be able to. That is, when the document size detection mechanism is installed in the document conveying device 200, it is not necessary to perform the control shown in FIGS.

  However, if a document size detection mechanism is installed in the document feeder 200, the cost increases. Therefore, in the present embodiment, the document size detection mechanism is not installed in the document conveyance device 200.

  Next, a case where the first conventional method is applied to the structure of the present embodiment will be described with reference to FIG. The first conventional method is a method in which the feeding of the next original D is started when the trailing edge of the preceding original D passes the detection position DP. In the following description, it is assumed that the document D to be transported is A4 size.

  In the first conventional method, as shown in FIG. 9, the registration sensor RS is turned on when the leading edge of the preceding document D reaches the detection position DP after the feeding of the preceding document D is started. Then, at time P31 when 22 ms elapses after the registration sensor RS is turned on, the rotation of the paper feed roller 26 is stopped, and the conveyance of the preceding document D by the registration roller pair 27 is started. Up to this point, the timing chart is the same as that shown in FIG.

  Further, when 707 ms has elapsed after the conveyance of the preceding document D by the registration roller pair 27 is started (time point P32), the trailing end of the preceding document D passes through the detection position DP. In the first conventional method, the feeding of the next original D is started at time P32. Here, in order to set the time from the start of conveyance of the preceding document D by the registration roller pair 27 to the start of conveyance of the next document D to a predetermined time T (1000 ms), the time point when the trailing edge of the preceding document D passes the detection position DP. At the point SP when 293 ms has elapsed from P32, the conveyance of the next original D by the registration roller pair 27 must be started.

  However, if the feeding of the next document D is started at the point P32 when the trailing edge of the preceding document D passes the detection position DP, it takes 310 ms to transport the next document D from the paper feed roller 26 to the registration roller pair 27, and thereafter Since it takes 5 ms to correct the skew of the next original D, the conveyance of the next original D by the registration roller pair 27 cannot be started at the time point SP. In this case, the conveyance of the next original D by the registration roller pair 27 is started at a time P33 when 315 ms elapses from the time P32 when the trailing edge of the preceding original D passes the detection position DP. That is, the time from the start of conveyance of the preceding document D by the registration roller pair 27 to the start of conveyance of the next document D is 1022 ms.

  As another conventional method (second conventional method), the feeding start timing of the next original D is measured based on the output value of the sensor whose detection position is the position between the paper feed roller 26 and the detection position DP. There is a way.

  Hereinafter, a case where the second conventional method is applied to the structure of the present embodiment will be described with reference to FIG. In the following description, a detection position between the paper feed roller 26 and the detection position DP is referred to as a paper feed detection position, and a sensor for detecting the presence or absence of the document D at the paper feed detection position is referred to as a paper feed sensor. In the following description, it is assumed that a position where the registration roller pair 27 has returned 86 mm upstream in the transport direction (a position advanced 41 mm downstream from the paper feed roller 26 in the transport direction) is the paper feed detection position. In the following description, it is assumed that the document D to be transported is A4 size.

  In the second conventional method, as shown in FIG. 10, when the leading document D starts feeding, the leading sensor is turned on when the leading edge of the leading document D reaches the feeding detection position (time point P41). To do. Similarly to the timing chart shown in FIG. 6, when the leading edge of the preceding document D reaches the detection position DP, the registration sensor RS is turned on. Thereafter, at time P42 when 22 ms has passed since the registration sensor RS was turned on, the rotation of the paper feed roller 26 is stopped, and the conveyance of the preceding document D by the registration roller pair 27 is started.

  Then, when 515 ms elapses from the conveyance start time P42 of the preceding document D by the registration roller pair 27 (time P43), the trailing edge of the preceding document D passes through the sheet feeding detection position, and the sheet feeding sensor is turned off. Here, in order to set the time from the start of conveyance of the preceding document D by the registration roller pair 27 to the start of conveyance of the next document D to a predetermined time T (1000 ms), from the conveyance start time P42 of the preceding document D by the registration roller pair 27. At the time P44 when 685 ms elapses, the feeding of the next original D must be started. Therefore, if the feeding of the next original D is started when 170 ms has elapsed from the time P43 when the paper feeding sensor is turned off, the feeding start time of the next original D is the time P44. As a result, the preceding original by the registration roller pair 27 is obtained. The time from the start of conveyance of D to the start of conveyance of the next original D is 1000 ms (conveyance of the next original D by the registration roller pair 27 is started at time P45).

  If the second conventional method is used, it is not necessary to perform the control shown in FIGS. However, when the second conventional method is used, it is necessary to provide a paper feed sensor, which leads to an increase in cost.

  As another conventional method (third conventional method), there is a method in which the rotation speed of the paper feed roller 26 is made faster than 410 mm / s.

  For example, in the timing chart shown in FIG. 9 (a method in which feeding of the next original D is started when the trailing edge of the preceding original D passes the detection position DP), the next from the paper supply roller 26 to the registration roller pair 27 is performed. Since it takes 310 ms to transport the document D and then 5 ms to correct the skew of the next document D, the transport of the next document D by the registration roller pair 27 cannot be started at the point SP. However, if the time taken to transport the next original D from the paper feed roller 26 to the registration roller pair 27 is shortened by applying the third conventional method, the next original D is conveyed by the registration roller pair 27 at the point SP. It can be started.

  If the third conventional method is used, it is not necessary to perform the control shown in FIGS. However, when the third conventional method is used, the conveyance speed of the document D is increased, so that damage to the document D conveyed while rubbing against the conveyance guide of the document conveyance path 22 may increase.

<Flow of control when feeding documents>
Hereinafter, the flow of control when the preceding document D is fed and then the next document D is fed will be described with reference to the flowchart shown in FIG. The start of the flowchart shown in FIG. 11 is when conveyance of the preceding document D by the registration roller pair 27 is started.

  In step S <b> 1, the document conveyance control unit 210 determines whether or not the first time T <b> 1 has elapsed from the start of conveyance of the preceding document D by the registration roller pair 27. As a result of the determination, if the first time T1 has elapsed, the process proceeds to step S2, and if the first time T1 has not elapsed, the determination in step S1 is repeated.

  In step S <b> 2, the document conveyance control unit 210 starts feeding the next document D by the feed roller 26. Thereafter, in step S <b> 3, the document conveyance control unit 210 determines whether or not the second time T <b> 2 has elapsed from the start of feeding the next document D by the feed roller 26. If it is determined that the second time T2 has elapsed, the process proceeds to step S4. If the second time T2 has not elapsed, the determination in step S3 is repeated.

  In step S4, the document conveyance control unit 210 determines whether the output value of the registration sensor RS is a value indicating the absence of the document D (whether the preceding document D passes the detection position DP). to decide. As a result of this determination, if the output value of the registration sensor RS is a value indicating the absence of the document D, the process proceeds to step S5. In step S <b> 5, the document conveyance control unit 210 continues feeding the next document D by the sheet feeding roller 26.

  On the other hand, if the output value of the registration sensor RS is a value indicating the presence of the document D in step S4, the process proceeds to step S6. In step S <b> 6, the document conveyance control unit 210 temporarily stops feeding the next document D by the sheet feeding roller 26.

  In step S <b> 7, the document conveyance control unit 210 determines whether the output value of the registration sensor RS has reached a value indicating the absence of the document D (whether the preceding document D has passed the detection position DP). . As a result of the determination, if the output value of the registration sensor RS does not become a value indicating the absence of the document D, the determination in step S7 is repeated, and if the output value of the registration sensor RS becomes a value indicating the absence of the document D, a step is performed. The process proceeds to S8. In step S8, the document conveyance control unit 210 resumes feeding the next document D by the sheet feeding roller 26.

  As described above, the document conveying apparatus 200 according to the present embodiment is arranged on the document conveying path 22 to feed the document D, the downstream side in the conveying direction with respect to the sheet feeding roller 26, and the document conveying path 22. Between the registration roller pair 27 (registration roller) for correcting the skew of the document D, and between the paper feed roller 26 and the registration roller pair 27 in the document conveyance path 22. The position is a detection position DP, a registration sensor RS that changes the output value according to the presence or absence of the document D at the detection position DP, and the leading end of the document D at the detection position DP and the trailing end passage based on the output value of the registration sensor RS. And a document conveyance control unit 210 (control unit) that controls the driving of the paper feed roller 26 and the registration roller pair 27, When conveying the original D Saga predetermined lengths plurality continuously, it is determined so as to start by the registration roller pair 27 to transport the document D at predetermined time intervals. Then, the document conveyance control unit 210 detects that the leading edge of the preceding document D has reached the detection position DP, and then registers the document D in the time required for the document D to travel between the detection position DP and the registration roller pair 27. When a time period for temporarily stopping the progress of the document D by the roller pair 27 has elapsed, the conveyance of the preceding document by the registration roller pair 27 is started, and the first conveyance from the start of the conveyance of the preceding document by the registration roller pair 27 is started. When the time T1 has elapsed, the paper feeding roller 26 starts feeding the next original D.

  In the configuration of this embodiment, when the first time T1 has elapsed from the start of conveyance of the preceding document D by the registration roller pair 27, the feeding roller 26 starts feeding the next document D, whereby the registration roller pair 27 When a predetermined time T has elapsed from the start of conveyance of the preceding document D, the leading edge of the next document D has already reached the registration roller pair 27 (the state where the progress of the next document D has been temporarily stopped by the registration roller pair 27) and Become. Accordingly, when the predetermined time T has elapsed from the start of transport of the preceding document D by the registration roller pair 27, transport of the next document D by the registration roller pair 27 can be easily started (a desired ipm can be realized). ).

  Further, in the present embodiment, as described above, the document conveyance control unit 210 has the document D at the detection position DP when the second time T2 has elapsed from the start of feeding the next document D by the feed roller 26. Is detected, the feeding of the next document D is temporarily stopped, and it is detected that there is no document D at the detection position DP, and then the feeding of the next document D is resumed, while the document D is detected at the detection position DP. If the absence is detected, the feeding of the next original D is continued. With this configuration, the leading edge of the next document D enters the detection position DP in a state where the distance between the preceding document D and the next document D is shorter than the minimum sheet distance, or the trailing edge of the preceding document D. It is possible to prevent the leading edge of the next document D from entering the detection position DP in a state where the side and the leading edge side of the next document D overlap. Thereby, it is possible to prevent the inconvenience that the registration sensor RS does not turn off (the arrival of the leading edge of the next original D at the detection position DP can be reliably detected).

  In the present embodiment, as described above, the minimum paper interval time is rotated from the predetermined position (second position) to the reference position (first position) when the trailing edge of the document D passes the detection position DP. This is the time required for the actuator 30 to stop within the range defined as the reference position. If such a time is set as the minimum paper interval time, after the trailing edge of the preceding document D passes the detection position DP, the actuator 30 stops within the range defined as the reference position, and then the leading edge of the next document D Can be made to enter the detection position DP (the arrival of the leading edge of the next original D at the detection position DP can be reliably detected).

  It should be thought that embodiment disclosed this time is an illustration and restrictive at no points. The scope of the present invention is shown not by the description of the above-described embodiment but by the scope of claims for patent, and further includes meanings equivalent to the scope of claims for patent and all modifications within the scope.

22 Document transport path 26 Feed roller 27 Registration roller pair (registration roller)
30 Actuator 100 Image Forming Device 200 Document Conveying Device 210 Document Conveying Control Unit (Control Unit)
DP detection position RS Registration sensor T Predetermined time T1 1st time T2 2nd time

Claims (4)

A paper feed roller for feeding a document to the document transport path;
A registration roller disposed downstream of the paper feed roller in the transport direction, temporarily stopping the progress of the document traveling along the document transport path, and correcting skew of the document;
A registration sensor that sets a position between the paper feed roller and the registration roller in the document transport path as a detection position, and changes an output value according to the presence or absence of a document at the detection position;
Based on the output value of the registration sensor, and detects the leading edge of the document at the detection position and the passage of the trailing edge, and includes a control unit that controls driving of the paper feeding roller and the registration roller,
When a plurality of documents having a predetermined length in the transport direction are continuously transported, it is determined that the transport of the document by the registration rollers is started every predetermined time.
The control unit detects that the leading edge of the preceding document has reached the detection position, and then proceeds with the registration roller during the time required for the document to travel between the detection position and the registration roller. When the time for adding a time to stop the recording has elapsed, the conveyance of the preceding document by the registration roller is started, and when the first time has elapsed from the start of conveyance of the preceding document by the registration roller, Let the roller start feeding the next document,
The first time is a positive value, and the time required for the document to travel between the paper feed roller and the registration roller from the predetermined time, and the time for temporarily stopping the progress of the document by the registration roller. Is a time obtained by subtracting. When the control unit detects that the preceding document is present at the detection position when a second time has elapsed from the start of feeding the next document by the feed roller, the control unit feeds the next document. If it is detected that the preceding document is not present at the detection position, the feeding of the next document is resumed. On the other hand, if it is detected that the preceding document is not present at the detection position, the next document is detected. Continue feeding,
The second time is a time obtained by subtracting a predetermined inter-paper time, which is a time required for the original to travel a predetermined inter-paper distance, from a time required for the original to advance between the paper feed roller and the detection position. The document conveying device according to claim 1, wherein: When there is a document at the detection position, the document is brought into contact with the document to rotate from the range defined as the first position to the second position, and when the trailing edge of the document passes through the detection position, the second position moves to the second position. An actuator that pivots to a first position;
The registration sensor is a sensor that detects the actuator, and outputs a value indicating that there is no document when the actuator is within a range defined as the first position, and the actuator detects the first position. A value indicating the presence of a document is output when it is rotated from the position to the second position,
The predetermined inter-sheet time is before the actuator that has been rotated from the second position to the first position due to the trailing edge of the document passing through the detection position stops within the range defined as the first position. The document conveying apparatus according to claim 2, wherein the time is a required time.   An image forming apparatus comprising the document conveying device according to claim 1.

Images