SHEET CONVEYING APPARATUS, IMAGE READING APPARATUS, AND SHEET CONVEYING METHOD

Abstract

To provide a sheet carrier, an image reader and a method of carrying a sheet that allow for suppressing the lowering of productivity and inhibiting jamming from occurring.SOLUTION: An image forming apparatus 100 comprises a determination processing section 43 that determines whether or not an original has a length equal to or smaller than a specified distance in a transport direction and a first drive control section 45 that, if the length has been determined equal to or smaller than the specified distance by the determination processing section 43, stops driving to a sheet-feed belt after a front end of the original contacted a register roller and before a rear end of the original passes through a contact point between the sheet-feed belt and a separation roller and, if the length has been determined exceeding the specified distance, stops driving to the sheet-feed belt after the front end of the original contacted a first transport roller and before the rear end of the original passes through the contact point.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a sheet conveying device, an image reading device, and a sheet conveying method. [Background technology]

[0002] There is known an image reading device equipped with an ADF (Auto Document Feeder) that transports a document to be read. For example, the ADF includes a paper feed belt, a separation roller, a registration roller, and a transport roller. The paper feed belt contacts the document and transports the document downstream in a transport direction. The separation roller forms a nip between the paper feed belt and the separation roller, and separates the document in contact with the paper feed belt from the other documents among the multiple documents transported to the nip. The registration roller transports the document downstream of the paper feed belt in the transport direction. The transport roller transports the document to an image reading position downstream of the registration roller in the transport direction.

[0003] Also, there is known an image reading device that changes the feeding control of the succeeding document depending on the length in the transport direction of the document that is transported first (see Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2018-108889 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, the registration roller may slip on the surface of the document, causing a delay in the transport of the document by the registration roller. If the delay is long, a paper feed retry is performed in which the drive of the registration roller is temporarily stopped and then driven again. When the paper feed retry is performed, the transport of the document is delayed by that amount, thereby reducing the productivity of the device. In response to this, the transport delay caused by the slip of the registration roller can be suppressed by continuing the transport of the document by the paper feed belt until the leading edge of the document comes into contact with the transport roller.

[0006] However, if the length of the document in the transport direction is short, the rear end of the document passes through the nip before the leading end of the document comes into contact with the transport roller. In this case, the following document is transported from the nip to the downstream side in the transport direction until the drive of the paper feed belt stops, and the following document stops in a state where it is sandwiched between the paper feed belt and the separation roller. This causes the following document to become curved, making it more likely to jam (paper jam) when the document is transported.

[0007] An object of the present invention is to provide a sheet conveying device, an image reading device, and a sheet conveying method that can suppress a decrease in productivity and the occurrence of a jam. [Means for solving the problem]

[0008] A sheet conveying device according to one aspect of the present invention includes a first conveying member, a separating member, a second conveying member, a third conveying member, a determination processing unit, and a first drive control unit. The first conveying member contacts a sheet conveyed in a predetermined conveying direction and conveys the sheet downstream in the conveying direction. The separating member is provided opposite the first conveying member across a first position where the sheet contacts the first conveying member, and is biased toward the first position, and separates a first sheet that contacts the first conveying member from a second sheet different from the first sheet among a plurality of sheets conveyed to the first position. The second conveying member contacts the sheet at a second position downstream of the first position in the conveying direction and conveys the sheet downstream in the conveying direction. The third conveying member contacts the sheet at a third position downstream of the second position in the conveying direction and conveys the sheet downstream in the conveying direction. The determination processing unit determines whether the length of the sheet in the transport direction is equal to or shorter than a specific distance based on a distance of a section from the first position to the third position in a transport path of the sheet. If the determination processing unit determines that the length is equal to or shorter than the specific distance, the first drive control unit stops driving the first transport member after the leading edge of the sheet in the transport direction reaches the second position and before the trailing edge of the sheet in the transport direction passes the first position, and if the determination processing unit determines that the length exceeds the specific distance, the first drive control unit stops driving the first transport member after the leading edge reaches the third position and before the trailing edge passes the first position.

[0009] According to another aspect of the present invention, there is provided an image reading apparatus including the sheet transporting device and an image reading section, the image reading section reading an image included on the sheet transported by the sheet transporting device.

[0010] A sheet transport method according to another aspect of the present invention is executed by a sheet transport device including a first transport member that contacts a sheet transported in a predetermined transport direction and transports the sheet downstream in the transport direction, a separating member that is provided opposite the first transport member across a first position where the sheet and the first transport member contact each other and is biased toward the first position and separates a first sheet that contacts the first transport member from a second sheet different from the first sheet among a plurality of sheets transported to the first position, a second transport member that contacts the sheet at a second position downstream of the first position in the transport direction and transports the sheet downstream in the transport direction, and a third transport member that contacts the sheet at a third position downstream of the second position in the transport direction and transports the sheet downstream in the transport direction, and includes the following determination step and drive control step. In the determination step, it is determined whether or not the length of the sheet in the transport direction is equal to or shorter than a specific distance based on a distance of a section from the first position to the third position in a transport path of the sheet. In the drive control step, if the judgment step determines that the length is less than the specific distance, the drive of the first conveying member is stopped after the leading edge of the sheet in the conveying direction reaches the second position and before the trailing edge of the sheet in the conveying direction passes the first position, and if the length is determined to exceed the specific distance, the drive of the first conveying member is stopped after the leading edge reaches the third position and before the trailing edge passes the first position. Effect of the Invention

[0011] According to the present invention, it is possible to suppress a decrease in productivity and to suppress the occurrence of jams. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a diagram showing a configuration of an image forming apparatus according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a block diagram showing a system configuration of the image forming apparatus according to the embodiment of the present invention. [Diagram 3] FIG. 3 is a diagram showing the configuration of the ADF of the image forming apparatus according to the embodiment of the present invention. [Figure 4] FIG. 4 is a flowchart showing an example of a transport control switching process executed in the image forming apparatus according to the embodiment of the present invention. [Diagram 5] FIG. 5 is a flowchart showing an example of a first conveyance control process executed in the image forming apparatus according to the embodiment of the present invention. [Figure 6] FIG. 6 is a flowchart showing an example of the second conveyance control process executed in the image forming apparatus according to the embodiment of the present invention. [Figure 7] FIG. 7 is a flowchart showing an example of the third conveyance control process executed in the image forming apparatus according to the embodiment of the present invention. [Figure 8] FIG. 8 is a flowchart showing an example of the fourth conveyance control process executed in the image forming apparatus according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. Note that the following embodiment is an example of the present invention, and is not intended to limit the technical scope of the present invention.

[0014] [Configuration of image forming apparatus 100] First, the configuration of an image forming apparatus 100 according to an embodiment of the present invention will be described with reference to Figures 1 and 2. Here, Figure 1 is a cross-sectional view showing the configuration of the image forming apparatus 100.

[0015] The image forming apparatus 100 is a multifunction machine having multiple functions such as a scanning function for reading an image from an original, a printing function for forming an image based on image data, a facsimile function, and a copy function. The image forming apparatus 100 is an example of an image reading apparatus of the present invention. The image reading apparatus of the present invention may be a scanner, a facsimile machine, a copy machine, or the like.

[0016] As shown in FIGS. 1 and 2, an image forming apparatus 100 includes an ADF (Auto Document Feeder) 1, an image reading unit 2, an image forming unit 3, a paper feeding unit 4, a control unit 5, and an operation display unit 6.

[0017] The ADF 1 conveys an original (an example of a sheet of the present invention) to be read by the scanning function.

[0018] The image reading unit 2 realizes the scanning function. For example, the image reading unit 2 includes a document table, a light source, multiple mirrors, an optical lens, and a CCD (Charge Coupled Device). The image reading unit 2 reads an image included in a document conveyed by the ADF 1, and outputs image data corresponding to the read image.

[0019] The image forming unit 3 realizes the printing function. For example, the image forming unit 3 forms an image on a sheet supplied from the paper feed unit 4 by an electrophotographic method. For example, the image forming unit 3 includes a photoconductor drum, a charging roller, an optical scanning device, a developing device, a transfer roller, a cleaning device, a fixing device, and a paper output tray.

[0020] The paper feed unit 4 supplies sheets to the image forming unit 3. For example, the paper feed unit 4 includes a paper feed cassette, a manual feed tray, a sheet transport path, and a plurality of transport rollers.

[0021] The control unit 5 controls the image forming apparatus 100 in an overall manner.

[0022] The operation display unit 6 is a user interface of the image forming apparatus 100. For example, the operation display unit 6 has a display unit such as a liquid crystal display that displays various information in response to control instructions from the control unit 5, and an operation unit such as operation keys or a touch panel that inputs various information to the control unit 5 in response to user operations.

[0023] [ADF1 Configuration] Next, the configuration of the ADF 1 will be described with reference to Figures 2 and 3. Figure 3 is a cross-sectional view showing the configuration of the ADF 1. In Figure 3, a transport path R1 for a document transported by the ADF 1 is indicated by a dashed line with an arrow.

[0024] As shown in Figures 2 and 3, the ADF 1 includes a document placement section 11, a housing 12, a pickup roller 13, a paper feed belt 14, a separation roller 15, a feed motor 16, a feed sensor 17, a registration roller 18, a registration motor 19, a first transport roller 20, a timing sensor 21, a CIS (Contact Image Sensor) 22, a second transport roller 23, a third transport roller 24, a paper discharge roller 25, and a paper discharge section 26.

[0025] A document to be transported is placed on the document placement unit 11. In the ADF 1, the document placed on the document placement unit 11 is transported in a transport direction D1 shown in FIG.

[0026] The document placement unit 11 is provided with a pair of side cursors 11A (see FIG. 3). Each of the side cursors 11A is provided to be movable in a width direction perpendicular to the transport direction D1 in the document placement unit 11. For example, the pair of side cursors 11A are connected to a rack and pinion (not shown), and are provided so that when one of the side cursors 11A moves in a first direction along the width direction, the other moves in a second direction opposite to the first direction. The pair of side cursors 11A clamp the document placed on the document placement unit 11 from both sides in the width direction, thereby regulating the position of the document in the width direction.

[0027] Further, the document placement unit 11 is provided with a signal output unit 11B (see FIG. 2). The signal output unit 11B outputs an electric signal according to the separation distance between the pair of side cursors 11A. For example, the signal output unit 11B is an electronic circuit including a variable resistor whose resistance value changes according to the rotation of the pinion, and outputs an electric signal according to the resistance value of the variable resistor.

[0028] Further, the document placement section 11 is provided with a size sensor 11C (see FIG. 2). The size sensor 11C is a sensor capable of detecting the presence or absence of a document at a predetermined reference position on the document placement section 11. For example, the size sensor 11C is a reflective optical sensor. For example, the reference position is a position that is exposed to the outside when an A4 portrait-sized document is placed on the document placement section 11, and is covered by the document when a B4 portrait-sized document is placed on the document placement section 11. The signal output section 11B and the size sensor 11C are used to detect the size of the document placed on the document placement section 11.

[0029] Further, a lift plate 11D (see FIG. 3) is provided on the document placement section 11. The lift plate 11D lifts the document placed on the document placement section 11 up to a contact position with the pickup roller 13.

[0030] Housing 12 houses rollers and the like used to transport the document. A document transport path is formed inside housing 12, leading from document placement unit 11 to paper discharge unit 26. In ADF 1, the document is transported along transport route R1 (see FIG. 3) leading from document placement unit 11 to paper discharge unit 26 through the transport path.

[0031] 3, an opening 12A is provided at the bottom of the housing 12. The opening 12A exposes a part of the transport path to the outside. In the opening 12A, the image reading unit 2 reads an image included in the document transported by the ADF 1.

[0032] Pickup roller 13 comes into contact with a first surface of the document lifted by lift plate 11D and transports the document in transport direction D1. The first surface is the upper surface of the document placed on document placement unit 11.

[0033] The paper feed belt 14 contacts the document conveyed by the pickup roller 13 in the conveying direction D1 and conveys the document downstream in the conveying direction D1. As shown in FIG. 3, the paper feed belt 14 is provided on the upper side of the conveying path R1 and contacts the first surface of the document conveyed by the pickup roller 13. The paper feed belt 14 is stretched by a driving roller 14A (see FIG. 3) and a driven roller 14B (see FIG. 3). As shown in FIG. 3, the driving roller 14A and the driven roller 14B are arranged in the order of the driving roller 14A and the driven roller 14B along the conveying direction D1. The document conveyed by the pickup roller 13 contacts the paper feed belt 14 downstream of the driving roller 14A in the conveying direction D1 and upstream of the driven roller 14B in the conveying direction D1. The paper feed belt 14 is an example of a first conveying member of the present invention. The positions of the driving roller 14A and the driven roller 14B may be reversed. The first transport member of the present invention may be a roller-shaped member.

[0034] The separation roller 15 is provided opposite the feed belt 14 across a first position P1 (see FIG. 3) where the document and the feed belt 14 come into contact with each other. As shown in FIG. 3, the separation roller 15 is provided below the conveying path R1. The separation roller 15 is biased toward the first position P1 by a coil spring (not shown). At the first position P1, the feed belt 14 is curved upward by the separation roller 15 biased toward the first position P1. The contact portion between the feed belt 14 and the separation roller 15 functions as a nip portion that holds the document. The separation roller 15 separates a first document (an example of a first sheet of the present invention) that comes into contact with the feed belt 14 from a second document (an example of a second sheet of the present invention) that is different from the first document, among the multiple documents conveyed to the first position P1. The separation roller 15 is an example of a separating member of the present invention.

[0035] For example, the separation roller 15 is driven in the direction of the arrow (clockwise direction) shown in Fig. 3 by a motor (not shown). The separation roller 15 is connected to a torque limiter (not shown) and receives a rotational driving force supplied from the motor via the torque limiter. When the rotational torque transmitted from the paper feed belt 14 exceeds a predetermined value, the torque limiter blocks the transmission path of the rotational driving force from the motor to the separation roller 15, causing the separation roller 15 to follow the paper feed belt 14.

[0036] The feed motor 16 drives the paper feed belt 14. Specifically, the feed motor 16 is connected to the drive roller 14A via a power transmission path (not shown) and supplies a rotational drive force to the drive roller 14A. This rotates the drive roller 14A, and drives the paper feed belt 14 in the direction of the arrow (clockwise direction) shown in FIG. 3.

[0037] The registration roller 18 comes into contact with the original at a second position P2 (see FIG. 3) downstream of the first position P1 in the transport direction D1, and transports the original downstream in the transport direction D1. As shown in FIG. 3, the registration roller 18 is provided above the transport path R1, and comes into contact with the first surface of the original transported by the paper feed belt 14. A driven roller 18A is provided below the registration roller 18, facing the registration roller 18 across the transport path R1. The driven roller 18A is provided in contact with the registration roller 18. The second position P2 is a contact position between the registration roller 18 and the driven roller 18A. The registration roller 18 is an example of a second transport member of the present invention.

[0038] The resist motor 19 drives the resist roller 18. Specifically, the resist motor 19 is connected to the resist roller 18 via a power transmission path (not shown), and supplies a rotational driving force to the resist roller 18. As a result, the resist roller 18 is driven in the direction of the arrow (clockwise direction) shown in FIG.

[0039] Feed sensor 17 detects the leading edge of the document in transport direction D1 at a fourth position P4 (see FIG. 3) that is downstream of first position P1 in transport direction D1 and upstream of second position P2 in transport direction D1. For example, feed sensor 17 is a reflective optical sensor. Feed sensor 17 is an example of a detection unit of the present invention.

[0040] The first transport roller 20 contacts the document at a third position P3 (see FIG. 3) downstream of the second position P2 in the transport direction D1, and transports the document downstream in the transport direction D1. As shown in FIG. 3, the first transport roller 20 is provided above the transport path R1, and contacts the first surface of the document transported by the registration roller 18. A driven roller 20A is provided below the first transport roller 20, facing the first transport roller 20 across the transport path R1. The driven roller 20A is provided in contact with the first transport roller 20. The third position P3 is a contact position between the first transport roller 20 and the driven roller 20A. The first transport roller 20 is an example of a third transport member of the present invention.

[0041] The CIS 22 reads an image on a second side of the document opposite to the first side at a sixth position P6 (see FIG. 3) that is downstream of the third position P3 in the transport direction D1.

[0042] The timing sensor 21 detects the leading edge of the document in the transport direction D1 at a fifth position P5 (see FIG. 3) that is downstream of the third position P3 in the transport direction D1 and upstream of the sixth position P6 in the transport direction D1. For example, the timing sensor 21 is a reflective optical sensor. The timing sensor 21 is used to control the operation of the CIS 22.

[0043] The second transport roller 23 transports the document, the second side of which has been read by the CIS 22, to the opening 12A. At the opening 12A, the image on the first side of the document is read by the image reading unit 2. The third transport roller 24 transports the document that has passed through the opening 12A to the paper discharge roller 25. The paper discharge roller 25 discharges the document transported by the third transport roller 24 to the paper discharge unit 26. The document transported along the transport path R1 is discharged to the paper discharge unit 26.

[0044] [Configuration of control unit 5] Next, the configuration of the control unit 5 will be described with reference to FIG.

[0045] As shown in FIG. 2, the control unit 5 includes a CPU 31, a ROM 32, and a RAM 33.

[0046] The CPU 31 is a processor that executes various types of arithmetic processing. The ROM 32 is a non-volatile storage device that prestores information such as control programs for causing the CPU 31 to execute various types of processing. The RAM 33 is a volatile storage device that is used as a temporary storage memory (work area) for the various types of processing executed by the CPU 31.

[0047] In the control unit 5, various control programs stored in advance in the ROM 32 are executed by the CPU 31. As a result, the image forming apparatus 100 is comprehensively controlled by the control unit 5. The control unit 5 may be configured with an electronic circuit such as an integrated circuit (ASIC). The control unit 5 may also be a control unit provided separately from a main control unit that comprehensively controls the image forming apparatus 100.

[0048] However, the registration roller 18 may slip on the surface of the document, causing a delay in the transport of the document by the registration roller 18. If the delay is long, the drive of the registration roller 18 is stopped once and the drive is restarted, and a paper feed retry is executed. For example, when the leading edge of the document is not detected by the timing sensor 21 during a predetermined time period from when the leading edge of the document is detected by the feed sensor 17, the paper feed retry is executed. When the paper feed retry is executed, the transport of the document is delayed accordingly, and the productivity of the image forming apparatus 100 is reduced. In response to this, the transport delay caused by the slip of the registration roller 18 can be suppressed by continuing the transport of the document by the paper feed belt 14 until the leading edge of the document reaches the third position P3.

[0049] However, if the length of the document in the transport direction D1 is short, the rear end of the document passes through the first position P1 before the leading end of the document reaches the third position P3. In this case, the succeeding document is transported from the first position P1 downstream in the transport direction D1 until the drive of the paper feed belt 14 stops, and the succeeding document stops in a state where it is sandwiched between the paper feed belt 14 and the separation roller 15. This causes the succeeding document to become curved, making it more likely to jam (paper jam) when the document is transported.

[0050] In contrast, in the image forming apparatus 100 according to the embodiment of the present invention, as described below, it is possible to suppress a decrease in productivity and to suppress the occurrence of jams.

[0051] As shown in FIG. 2, the control unit 5 includes a reception processing unit 41, a detection processing unit 42, a determination processing unit 43, an acquisition processing unit 44, a first drive control unit 45, a second drive control unit 46, and a setting processing unit 47.

[0052] Specifically, a transport control program for causing the CPU 31 to execute a transport control switching process (see FIG. 4) described below is prestored in the ROM 32. The control unit 5 executes the transport control program stored in the ROM 32, thereby functioning as a reception processing unit 41, a detection processing unit 42, a determination processing unit 43, an acquisition processing unit 44, a first drive control unit 45, a second drive control unit 46, and a setting processing unit 47. Here, an apparatus including the ADF 1 and the control unit 5 is an example of a sheet transport device of the present invention.

[0053] The reception processing unit 41 receives a setting operation for setting items related to the transport of the document by the ADF 1 .

[0054] For example, the reception processing unit 41 displays a setting screen used for the setting operation on the operation display unit 6 in response to a predetermined calling operation on the operation display unit 6. On the setting screen, it is possible to set the document transport mode, which is one of the setting items. Also, on the setting screen, it is possible to set the document thickness, which is one of the setting items.

[0055] Here, on the setting screen, the transport mode can be set to either a first mode or a second mode. In the first mode, skew correction of the document is performed using the registration roller 18. On the other hand, in the second mode, the skew correction is not performed. The first mode is an example of a specific mode of the present invention.

[0056] Furthermore, on the setting screen, the thickness of the document can be set in three stages: “thick,” “normal,” and “thin.” The thickness of the document may be set by a numerical value or by the type of paper.

[0057] It should be noted that the size of the document or the length of the document in the transport direction D1 may be set on the setting screen. In this case, the ADF 1 may not be provided with the signal output unit 11B and the size sensor 11C. Also, the transport mode may not be set on the setting screen. In this case, the ADF 1 may always transport the document in the first mode or the second mode.

[0058] After accepting the setting operation, the reception processing unit 41 sequentially transports the documents placed on the document placement unit 11 and accepts an operation to execute a document reading process for reading the image of each document being transported.

[0059] For example, when the reception processing unit 41 receives the setting operation, it causes an execution operation screen used for the execution operation to be displayed on the operation display unit 6. For example, on the execution operation screen, the setting contents of each of the setting items are displayed.

[0060] The detection processing unit 42 detects the size of the document placed on the document placement unit 11 .

[0061] For example, the detection processing unit 42 detects the size of the document placed on the document placement unit 11 in the following procedure.

[0062] First, the detection processing unit 42 detects the length in the width direction of the document placed on the document placing unit 11 based on the electrical signal output from the signal output unit 11B. Next, the detection processing unit 42 extracts one or more standard sizes whose size in the width direction matches that of the document placed on the document placing unit 11 from a plurality of predetermined standard sizes.

[0063] Here, when one standard size is extracted, the detection processing unit 42 determines that the standard size is the size of the document placed on the document placement unit 11. When a plurality of standard sizes are extracted, the detection processing unit 42 determines that the one standard size narrowed down based on the detection result by the size sensor 11C is the size of the document placed on the document placement unit 11.

[0064] The determination processing unit 43 determines whether the length of the document in the transport direction D1 is equal to or less than a specific distance based on the distance of a specific section from the first position P1 to the third position P3 on the transport path R1 (see FIG. 3).

[0065] For example, the specific distance is a distance obtained by adding a predetermined first distance to the distance of the specific section.

[0066] For example, the determination processing unit 43 determines, based on the size of the document detected by the detection processing unit 42, whether or not the length of the document in the transport direction D1 is equal to or less than the specific distance.

[0067] The specific distance may be equal to or shorter than the specific section. The determination processor 43 may determine whether the length of the document in the transport direction D1 is equal to or shorter than the specific distance based on the size of the document set on the setting screen or the length of the document in the transport direction D1. In this case, the controller 5 may not include the detection processor 42.

[0068] The acquisition processing unit 44 acquires the thickness of the document.

[0069] For example, the acquisition processing unit 44 acquires the thickness of the document set on the setting screen as the thickness of the document placed on the document placement unit 11 .

[0070] A thickness sensor for detecting the thickness of the document may be provided between the first position P1 and the second position P2 on the transport path R1 (see FIG. 3). For example, the thickness sensor is an optical sensor or an ultrasonic sensor. In this case, the acquisition processing unit 44 may acquire the thickness of the document using the thickness sensor.

[0071] For example, when the document reading process is executed, the acquisition processing unit 44 may perform a process of transporting the top document on the document loading unit 11 to a detection position by the thickness sensor, detecting the thickness of the document using the thickness sensor, and returning the document to the first position P1 as a pre-processing step of the document reading process.

[0072] When the transport mode is the first mode, the second drive control unit 46 starts driving the registration roller 18 when the elapsed time from when the feed sensor 17 detects the leading edge of the document exceeds a predetermined first reference time.

[0073] Here, the first reference time is a time longer than the time it takes for the document to be transported from the fourth position P4 (see FIG. 3) to the second position P2 by the paper feed belt 14. The first reference time is also a time required for the document transported by the paper feed belt 14 to be deflected by a predetermined amount after the document hits the contact portion between the registration roller 18 and the driven roller 18A. In the skew correction, the drive of the registration roller 18 is not started until the deflection is formed in the document, thereby correcting the inclination of the document with respect to the transport direction D1.

[0074] Furthermore, when the transport mode is the second mode, the second drive control section 46 starts driving the registration rollers 18 before the leading edge of the document in the transport direction D1 reaches the second position P2 (see FIG. 3).

[0075] For example, in the case where the transport mode is the second mode, the second drive control section 46 starts driving the registration rollers 18 when the feed sensor 17 detects the leading edge of the document.

[0076] When the judgment processing unit 43 determines that the length of the document in the transport direction D1 is less than the specific distance, the first drive control unit 45 stops driving the paper feed belt 14 after the leading end of the document in the transport direction D1 reaches the second position P2 (see Figure 3) and before the trailing end of the document in the transport direction D1 passes the first position P1.

[0077] In addition, when the judgment processing unit 43 determines that the length of the original document in the transport direction D1 exceeds the specific distance, the first drive control unit 45 stops driving the paper feed belt 14 after the leading end of the original document in the transport direction D1 reaches the third position P3 (see Figure 3) and before the trailing end of the original document in the transport direction D1 passes the first position P1.

[0078] For example, the first drive control unit 45 determines the timing to stop driving the paper feed belt 14 based on the elapsed time from when the feed sensor 17 detects the leading edge of the document.

[0079] For example, when the determination processing unit 43 determines that the length of the document in the transport direction D1 is equal to or shorter than the specific distance and when the transport mode is the first mode, the first drive control unit 45 stops driving the paper feed belt 14 when the elapsed time from when the feed sensor 17 detected the leading edge of the document exceeds the first reference time. For example, the first drive control unit 45 stops driving the paper feed belt 14 after a predetermined time has elapsed since the second drive control unit 46 started driving the registration roller 18.

[0080] Furthermore, when the determination processing unit 43 determines that the length of the document in the transport direction D1 is equal to or shorter than the specific distance and the transport mode is the second mode, the first drive control unit 45 stops driving the feed belt 14 when the elapsed time from when the feed sensor 17 detects the leading edge of the document exceeds a predetermined second reference time. Here, the second reference time is a time that is longer than the transport time of the document by the feed belt 14 from the fourth position P4 (see FIG. 3) to the second position P2 and is set by the setting processing unit 47.

[0081] Furthermore, when the determination processing unit 43 determines that the length of the document in the transport direction D1 exceeds the specific distance and when the transport mode is the first mode, the first drive control unit 45 stops driving the paper feed belt 14 when the elapsed time from when the feed sensor 17 detects the leading edge of the document exceeds a predetermined third reference time. For example, the third reference time is a time longer than the sum of the first reference time and the transport time of the document by the registration roller 18 from the second position P2 (see FIG. 3) to the third position P3.

[0082] Furthermore, when the determination processing unit 43 determines that the length of the document in the transport direction D1 exceeds the specific distance and when the transport mode is the second mode, the first drive control unit 45 stops driving the paper feed belt 14 when the elapsed time from when the feed sensor 17 detects the leading edge of the document exceeds a predetermined fourth reference time. For example, the fourth reference time is a time longer than the sum of the transport time of the document by the paper feed belt 14 from the fourth position P4 (see FIG. 3) to the second position P2 and the transport time of the document by the registration roller 18 from the second position P2 to the third position P3.

[0083] When the determination processing unit 43 determines that the length of the document in the transport direction D1 exceeds the specific distance, the first drive control unit 45 may use the timing sensor 21 (see FIG. 3) to determine the timing to stop driving the paper feed belt 14. For example, when the timing sensor 21 detects the leading edge of the document, the first drive control unit 45 may stop driving the paper feed belt 14. In this case, the first distance may be equal to or greater than the distance of the section from the third position P3 to the fifth position P5 on the transport path R1.

[0084] Further, a document sensor for detecting the leading edge of the document in the transport direction D1 may be provided between the second position P2 and the third position P3 on the transport path R1 (see FIG. 3). For example, the document sensor is a reflective optical sensor. In this case, the first drive control unit 45 may use the document sensor to determine the timing to stop driving the paper feed belt 14 when the determination processing unit 43 determines that the length of the document in the transport direction D1 is equal to or shorter than the specific distance. For example, the first drive control unit 45 may stop driving the paper feed belt 14 when the leading edge of the document is detected by the document sensor.

[0085] The setting processing unit 47 sets the second reference time based on the thickness of the document acquired by the acquisition processing unit 44 .

[0086] For example, in the image forming apparatus 100, table data showing the correspondence between the thickness of the document and the candidate time that is a candidate for the second reference time is stored in advance in the ROM 32. In the table data, the correspondence between the thickness of the document and the candidate time is determined so that the thicker the document is, the longer the candidate time is. This is because the thicker the document is, the more likely it is that the feed belt 14 will slip on the surface of the document, and the more likely it is that a delay will occur in the transport of the document by the feed belt 14.

[0087] Then, the setting processing unit 47 sets the second reference time by using the table data. Specifically, the setting processing unit 47 sets the candidate time associated with the thickness of the document acquired by the acquisition processing unit 44 in the table data as the second reference time.

[0088] The second reference time may be a fixed time that is determined in advance. In this case, the control unit 5 does not need to include the acquisition processing unit 44 and the setting processing unit 47.

[0089] [Transport control switching process] 4, a sheet conveying method of the present invention will be described together with an example of a procedure of a conveying control switching process executed by the control unit 5 in the image forming apparatus 100. Here, steps S11, S12, etc. indicate numbers of processing procedures (steps) executed by the control unit 5.

[0090] For example, the transport control switching process is executed when the execution operation of the document reading process is performed on the execution operation screen. In the following description, it is assumed that the transport mode and the thickness of the document are set on the setting screen.

[0091] <Step S11> First, in step S11, the control unit 5 detects the size of the document placed on the document placement unit 11. Here, the process of step S11 is executed by the detection processing unit 42 of the control unit 5.

[0092] <Step S12> In step S12, the control unit 5 determines whether the length of the document in the transport direction D1 is equal to or shorter than the specific distance based on the size of the document detected in step S11. The process of step S12 is an example of a determination step of the present invention, and is executed by the determination processing unit 43 of the control unit 5.

[0093] Here, when the control unit 5 determines that the length of the document in the transport direction D1 is equal to or less than the specific distance (Yes in S12), the control unit 5 shifts the process to step S13. On the other hand, when the length of the document in the transport direction D1 exceeds the specific distance (No in S12), the control unit 5 shifts the process to step S18.

[0094] <Step S13> In step S13, the control section 5 determines whether or not the transport mode is set to the second mode.

[0095] Here, when the control unit 5 determines that the transport mode is set to the second mode (Yes side of S13), the control unit 5 shifts the process to step S14. On the other hand, when the transport mode is not set to the second mode (No side of S13), the control unit 5 shifts the process to step S17.

[0096] <Step S14> In step S14, the control unit 5 acquires the thickness of the document. Here, the process of step S14 is executed by the acquisition processing unit 44 of the control unit 5.

[0097] Specifically, the control unit 5 acquires the thickness of the document set on the setting screen as the thickness of the document placed on the document placement unit 11.

[0098] <Step S15> In step S15, the control unit 5 sets the second reference time based on the thickness of the document acquired in step S 14. Here, the process of step S15 is executed by the setting processing unit 47 of the control unit 5.

[0099] Specifically, the control unit 5 sets the candidate time associated with the thickness of the document acquired in step S14 in the table data as the second reference time.

[0100] <Step S16> In step S16, the control unit 5 executes a first transport control process, which will be described later.

[0101] <Step S17> In step S17, the control unit 5 executes a second transport control process, which will be described later.

[0102] <Step S18> In step S18, the control section 5 determines whether or not the transport mode is set to the second mode.

[0103] Here, when the control unit 5 determines that the transport mode is set to the second mode (Yes side of S18), the control unit 5 shifts the process to step S19. On the other hand, when the transport mode is not set to the second mode (No side of S18), the control unit 5 shifts the process to step S20.

[0104] <Step S19> In step S19, the control unit 5 executes a third transport control process, which will be described later.

[0105] <Step S20> In step S20, the control unit 5 executes a fourth transport control process, which will be described later.

[0106] [First transport control process] Next, a first transport control process executed in step S16 of the transport control switching process will be described with reference to Fig. 5. The first transport control process is a process for controlling the driving of the paper feed belt 14 and the registration roller 18. In addition to the first transport control process, the control unit 5 executes a fifth transport control process for controlling the driving of the first transport roller 20, the second transport roller 23, the third transport roller 24, and the paper discharge roller 25. In addition to the first transport control process, the control unit 5 executes a second reading process for reading an image on the second side of the document using the CIS 22, and a first reading process for reading an image on the first side of the document using the image reading unit 2.

[0107] <Step S31> First, in step S31, the control section 5 judges whether or not the timing for feeding the document has arrived.

[0108] Here, when the control unit 5 determines that the paper feed timing has arrived (Yes side of S31), it shifts the process to step S32. On the other hand, when the paper feed timing has not arrived (No side of S31), the control unit 5 waits for the paper feed timing to arrive in step S31.

[0109] <Step S32> In step S32, the control unit 5 starts driving the paper feed belt 14. Here, the process of step S32 is executed by the first drive control unit 45 of the control unit 5.

[0110] Specifically, the control unit 5 starts the feed motor 16 to drive the feed motor 16 at a predetermined speed. As a result, a rotational driving force generated by the feed motor 16 is supplied to the driving roller 14A, and the driving of the driving roller 14A and the paper feed belt 14 is started.

[0111] <Step S33> In step S33, the control section 5 determines whether the feed sensor 17 has detected the leading edge of the document.

[0112] Here, if the control unit 5 determines that the leading edge of the document has been detected by the feed sensor 17 (Yes in S33), it shifts the process to step S34. If the leading edge of the document has not been detected (No in S33), the control unit 5 waits for the leading edge of the document to be detected by the feed sensor 17 in step S33.

[0113] <Step S34> In step S34, the control unit 5 starts driving the registration rollers 18. Here, the process of step S34 is executed by the second drive control unit 46 of the control unit 5.

[0114] Specifically, the control unit 5 starts the registration motor 19 to drive the registration motor 19 at a predetermined speed. As a result, the rotational driving force generated by the registration motor 19 is supplied to the registration roller 18, and the driving of the registration roller 18 is started.

[0115] <Step S35> In step S35, the control section 5 determines whether or not the second reference time has elapsed since the timing at which the leading edge of the document was detected in step S33.

[0116] Here, when the control unit 5 determines that the second reference time has elapsed since the timing when the leading edge of the document was detected in step S33 (Yes side of S35), it shifts the process to step S36. On the other hand, when the second reference time has not elapsed (No side of S35), the control unit 5 waits for the second reference time to elapse in step S35.

[0117] <Step S36> In step S36, the control unit 5 stops driving the paper feed belt 14. Here, the process of step S36 is an example of a drive control step of the present invention, and is executed by the first drive control unit 45 of the control unit 5.

[0118] After executing the process of step S36, the control unit 5 stops driving the registration rollers 18 at a predetermined timing, and shifts the process to step S37.

[0119] <Step S37> In step S37, the control section 5 determines whether or not the transport of the original is completed.

[0120] For example, the control unit 5 determines that the transport of the document is completed when there is no document on the document placement unit 11. The control unit 5 can determine whether or not there is a document on the document placement unit 11 by using a sensor (not shown) provided on the document placement unit 11.

[0121] Here, when the control unit 5 determines that the transport of the document has been completed (Yes side of S37), it ends the first transport control process. On the other hand, when the transport of the document has not been completed (No side of S37), the control unit 5 shifts the process to step S31.

[0122] [Second transport control process] Next, the second transport control process executed in step S17 of the transport control switching process will be described with reference to Fig. 6. The second transport control process is a process for controlling the driving of the paper feed belt 14 and the registration roller 18. The control unit 5 executes the fifth transport control process, the second reading process, and the first reading process in addition to the second transport control process.

[0123] <Step S41> First, in step S41, the control section 5 judges whether or not the timing for feeding the original has arrived.

[0124] Here, when the control unit 5 determines that the paper feed timing has arrived (Yes side of S41), it shifts the process to step S42. On the other hand, when the paper feed timing has not arrived (No side of S41), the control unit 5 waits for the paper feed timing to arrive in step S41.

[0125] <Step S42> In step S42, the control unit 5 starts driving the paper feed belt 14. Here, the process of step S42 is executed by the first drive control unit 45 of the control unit 5.

[0126] <Step S43> In step S43, the control section 5 determines whether the feed sensor 17 has detected the leading edge of the document.

[0127] Here, if the control unit 5 determines that the leading edge of the document has been detected by the feed sensor 17 (Yes side of S43), it shifts the process to step S44. If the leading edge of the document has not been detected (No side of S43), the control unit 5 waits for the leading edge of the document to be detected by the feed sensor 17 in step S43.

[0128] <Step S44> In step S44, the control section 5 judges whether or not the first reference time has elapsed from the timing at which the leading edge of the document was detected in step S43.

[0129] Here, when the control unit 5 determines that the first reference time has elapsed since the timing when the leading edge of the document was detected in step S43 (Yes side of S44), it shifts the process to step S45. On the other hand, when the first reference time has not elapsed (No side of S44), the control unit 5 waits for the first reference time to elapse in step S44.

[0130] <Step S45> In step S45, the control unit 5 starts driving the registration rollers 18. Here, the process of step S45 is executed by the second drive control unit 46 of the control unit 5.

[0131] <Step S46> In step S46, the control unit 5 stops driving the paper feed belt 14. Here, the process of step S46 is an example of a drive control step of the present invention, and is executed by the first drive control unit 45 of the control unit 5.

[0132] For example, the control unit 5 stops driving the paper feed belt 14 after a predetermined time has elapsed since the driving of the registration roller 18 was started in step S45.

[0133] After executing the process of step S46, the control unit 5 stops driving the registration rollers 18 at a predetermined timing, and shifts the process to step S47.

[0134] <Step S47> In step S47, the control section 5 determines whether or not the transport of the original is completed.

[0135] Here, when the control unit 5 determines that the transport of the document has been completed (Yes side of S47), it ends the second transport control process. On the other hand, when the transport of the document has not been completed (No side of S47), the control unit 5 shifts the process to step S41.

[0136] [Third transport control process] Next, a third transport control process executed in step S19 of the transport control switching process will be described with reference to Fig. 7. The third transport control process is a process for controlling the driving of the paper feed belt 14 and the registration roller 18. The control unit 5 executes the fifth transport control process, the second reading process, and the first reading process in addition to the third transport control process.

[0137] <Step S51> First, in step S51, the control section 5 judges whether or not the timing for feeding the original has arrived.

[0138] Here, when the control unit 5 determines that the paper feed timing has arrived (Yes side of S51), it shifts the process to step S52. On the other hand, when the paper feed timing has not arrived (No side of S51), the control unit 5 waits for the paper feed timing to arrive in step S51.

[0139] <Step S52> In step S52, the control unit 5 starts driving the paper feed belt 14. Here, the process of step S52 is executed by the first drive control unit 45 of the control unit 5.

[0140] <Step S53> In step S53, the control section 5 determines whether the feed sensor 17 has detected the leading edge of the document.

[0141] Here, if the control unit 5 determines that the leading edge of the document has been detected by the feed sensor 17 (Yes in S53), it shifts the process to step S54. If the leading edge of the document has not been detected (No in S53), the control unit 5 waits for the leading edge of the document to be detected by the feed sensor 17 in step S53.

[0142] <Step S54> In step S54, the control unit 5 starts driving the registration rollers 18. Here, the process of step S54 is executed by the second drive control unit 46 of the control unit 5.

[0143] <Step S55> In step S55, the control section 5 judges whether or not the fourth reference time has elapsed from the timing at which the leading edge of the document was detected in step S53.

[0144] Here, if the control unit 5 determines that the fourth reference time has elapsed since the timing when the leading edge of the document was detected in step S53 (Yes side of S55), it shifts the process to step S56. If the fourth reference time has not elapsed (No side of S55), the control unit 5 waits for the fourth reference time to elapse in step S55.

[0145] <Step S56> In step S56, the control unit 5 stops driving the paper feed belt 14. Here, the process of step S56 is an example of a drive control step of the present invention, and is executed by the first drive control unit 45 of the control unit 5.

[0146] After executing the process of step S56, the control unit 5 stops driving the registration rollers 18 at a predetermined timing, and shifts the process to step S57.

[0147] <Step S57> In step S57, the control section 5 determines whether or not the transport of the original is completed.

[0148] Here, when the control unit 5 determines that the transport of the document has been completed (Yes side of S57), it ends the third transport control process. On the other hand, when the transport of the document has not been completed (No side of S57), the control unit 5 shifts the process to step S51.

[0149] [Fourth transport control process] Next, a fourth transport control process executed in step S20 of the transport control switching process will be described with reference to Fig. 8. The fourth transport control process is a process for controlling the driving of the paper feed belt 14 and the registration roller 18. The control unit 5 executes the fifth transport control process, the second reading process, and the first reading process in addition to the fourth transport control process.

[0150] <Step S61> First, in step S61, the control section 5 judges whether or not the timing for feeding the original has arrived.

[0151] Here, when the control unit 5 determines that the paper feed timing has arrived (Yes side of S61), it shifts the process to step S62. On the other hand, when the paper feed timing has not arrived (No side of S61), the control unit 5 waits for the paper feed timing to arrive in step S61.

[0152] <Step S62> In step S62, the control unit 5 starts driving the paper feed belt 14. Here, the process of step S62 is executed by the first drive control unit 45 of the control unit 5.

[0153] <Step S63> In step S63, the control section 5 determines whether the feed sensor 17 has detected the leading edge of the document.

[0154] Here, if the control unit 5 determines that the leading edge of the document has been detected by the feed sensor 17 (Yes in S63), it shifts the process to step S64. If the leading edge of the document has not been detected (No in S63), the control unit 5 waits for the leading edge of the document to be detected by the feed sensor 17 in step S63.

[0155] <Step S64> In step S64, the control section 5 determines whether or not the first reference time has elapsed since the timing at which the leading edge of the document was detected in step S63.

[0156] Here, when the control unit 5 determines that the first reference time has elapsed since the timing when the leading edge of the document was detected in step S63 (Yes side of S64), it shifts the process to step S65. On the other hand, when the first reference time has not elapsed (No side of S64), the control unit 5 waits for the first reference time to elapse in step S64.

[0157] <Step S65> In step S65, the control unit 5 starts driving the registration rollers 18. Here, the process of step S65 is executed by the second drive control unit 46 of the control unit 5.

[0158] <Step S66> In step S66, the control section 5 determines whether or not the third reference time has elapsed since the timing at which the leading edge of the document was detected in step S63.

[0159] Here, when the control unit 5 determines that the third reference time has elapsed since the timing when the leading edge of the document was detected in step S63 (Yes side of S66), it shifts the process to step S67. On the other hand, when the third reference time has not elapsed (No side of S66), the control unit 5 waits for the third reference time to elapse in step S66.

[0160] <Step S67> In step S67, the control unit 5 stops driving the paper feed belt 14. Here, the process of step S67 is an example of a drive control step of the present invention, and is executed by the first drive control unit 45 of the control unit 5.

[0161] After executing the process of step S67, the control unit 5 stops driving the registration rollers 18 at a predetermined timing, and shifts the process to step S68.

[0162] <Step S68> In step S68, the control section 5 determines whether or not the transport of the original is completed.

[0163] Here, when the control unit 5 determines that the transport of the document has been completed (Yes side of S68), it ends the fourth transport control process. On the other hand, when the transport of the document has not been completed (No side of S68), the control unit 5 shifts the process to step S61.

[0164] In this manner, in the image forming apparatus 100, when the length of the document in the transport direction D1 is equal to or less than the specific distance, the drive of the paper feed belt 14 is stopped after the leading edge of the document reaches the second position P2 (see FIG. 3) and before the trailing edge of the document passes the first position P1. This makes it possible to prevent the following document from being transported downstream in the transport direction D1 from the first position P1 before the drive of the paper feed belt 14 is stopped when the trailing edge of the document passes the first position P1 before the leading edge of the document comes into contact with the first transport roller 20.

[0165] Furthermore, in the image forming apparatus 100, when the length of the document in the transport direction D1 exceeds the specific distance, the drive of the paper feed belt 14 is stopped after the leading edge of the document reaches the third position P3 (see FIG. 3) and before the trailing edge of the document passes the first position P1. This makes it possible to suppress a transport delay caused by slippage of the registration roller 18 when the trailing edge of the document passes the first position P1 after the leading edge of the document comes into contact with the first transport roller 20.

[0166] Therefore, in the image forming apparatus 100, it is possible to suppress a decrease in productivity and to suppress the occurrence of paper jams.

[0167] Furthermore, in the image forming apparatus 100, the timing to stop driving the paper feed belt 14 is determined based on the elapsed time from when the feed sensor 17 detects the leading edge of the document. This makes it possible to reduce the number of sensors compared to a configuration in which a sensor is provided for detecting that the leading edge of the document has reached the second position P2 or the third position P3. Furthermore, by using the feed sensor 17 also for driving control of the registration rollers 18, the number of sensors can be further reduced.

[0168] Furthermore, in the image forming apparatus 100, when the length of the document in the transport direction D1 is equal to or less than the specific distance and the transport mode is not the first mode, if the elapsed time from when the feed sensor 17 detects the leading edge of the document exceeds the second reference time that is longer than the transport time of the document from the fourth position P4 to the second position P2 by the document feed belt 14, the drive of the document feed belt 14 is stopped. This makes it possible to suppress the execution of the document feed retry caused by the document feed belt 14 slipping on the surface of the document when the skew correction is not performed.

[0169] Furthermore, in the image forming apparatus 100, the second reference time is set based on the thickness of the document. This makes it possible to reduce the drive amount of the feed motor 16 while suppressing the execution of the paper feed retry caused by the paper feed belt 14 slipping on the surface of the document.

[0170] The present invention may be applied to the paper feed section 4. In this case, the sheet of the present invention is a sheet supplied to the image forming section 3 by the paper feed section 4. [Explanation of symbols]

[0171] 1 ADF 2 Image reading section 3. Image forming section 4 Paper feed section 5. Control section 6 Operation display section 14 Paper feed belt 15 Separation roller 16 Feed motor 17 Feed Sensor 18 Resist Roller 19 Resist Motor 20 First conveyor roller 21 Timing sensor 41 Reception department 42 Detection processing section 43 Judgment processing unit 44 Acquisition processing unit 45 First drive control section 46 Second drive control section 47 Setting processing section 100 Image forming device

Claims

1. a first conveying member that comes into contact with a sheet conveyed in a predetermined conveying direction and conveys the sheet downstream in the conveying direction; a separating member that is provided opposite the first conveying member across a first position where the sheet and the first conveying member come into contact with each other, is biased toward the first position, and separates a first sheet that comes into contact with the first conveying member from a second sheet that is different from the first sheet, among the multiple sheets conveyed to the first position; a second conveying member that contacts the sheet at a second position downstream of the first position in the conveying direction and conveys the sheet downstream in the conveying direction; a third conveying member that contacts the sheet at a third position downstream of the second position in the conveying direction and conveys the sheet downstream in the conveying direction; a determination processing unit that determines whether or not a length of the sheet in the transport direction is equal to or shorter than a specific distance based on a distance of a section from the first position to the third position on a transport path of the sheet; a first drive control unit that, when it is determined by the determination processing unit that the length is equal to or shorter than the specific distance, stops driving the first conveying member after the leading edge of the sheet in the conveying direction reaches the second position and before the trailing edge of the sheet in the conveying direction passes the first position, and, when it is determined that the length exceeds the specific distance, stops driving the first conveying member after the leading edge reaches the third position and before the trailing edge passes the first position; a detection unit that detects the leading end at a fourth position that is downstream of the first position in the conveying direction and upstream of the second position in the conveying direction; A sheet conveying apparatus comprising: the first drive control unit determines a timing to stop driving the first conveying member based on an elapsed time from when the detection unit detected the leading end, when it is determined that the length is equal to or shorter than the specific distance, the first drive control unit stops driving the first conveying member when an elapsed time from when the detection unit detected the leading end exceeds a first reference time that is longer than a conveying time of the sheet from the fourth position to the second position by the first conveying member; The sheet conveying device includes: a second drive control unit that starts driving the second conveying member when an elapsed time from when the leading edge is detected by the detection unit exceeds the first reference time, the second drive control unit starts driving the second conveying member when a time elapsed since the detection of the leading edge by the detection unit exceeds the first reference time when a conveying mode of the sheet is a predetermined specific mode, and starts driving the second conveying member before the leading edge reaches the second position when the conveying mode is not the specific mode; The first drive control unit, when it is determined that the length is equal to or less than the specific distance and the transport mode is not the specific mode, stops driving the first transport member when the elapsed time from when the detection unit detects the leading edge exceeds a second reference time that is longer than the transport time.

2. An acquisition processing unit that acquires the thickness of the sheet; a setting processing unit that sets the second reference time based on the thickness of the sheet acquired by the acquisition processing unit; The sheet transport device according to claim 1 .

3. The first conveying member includes a belt-like member. The sheet transport device according to claim 1 .

4. A sheet conveying device according to any one of claims 1 to 3, an image reading unit that reads an image included on the sheet conveyed by the sheet conveying device; An image reading device comprising:

5. a first conveying member that contacts a sheet conveyed in a predetermined conveying direction and conveys the sheet downstream in the conveying direction; a separating member that is provided opposite the first conveying member across a first position where the sheet and the first conveying member come into contact with each other, and is biased toward the first position, and separates a first sheet that contacts the first conveying member among a plurality of sheets conveyed to the first position from a second sheet different from the first sheet; a second conveying member that contacts the sheet at a second position downstream of the first position in the conveying direction and conveys the sheet downstream in the conveying direction; a third conveying member that contacts the sheet at a third position downstream of the second position in the conveying direction and conveys the sheet downstream in the conveying direction; and a detection unit that detects a leading edge of the sheet in the conveying direction at a fourth position downstream of the first position in the conveying direction and upstream of the second position in the conveying direction, a determining step of determining whether or not a length of the sheet in the transport direction is equal to or shorter than a specific distance based on a distance of a section from the first position to the third position on a transport path of the sheet; a first drive control step of stopping the drive of the first conveying member after the leading edge reaches the second position and before the trailing edge of the sheet in the conveying direction passes the first position when it is determined that the length is equal to or shorter than the specific distance by the determination step, and stopping the drive of the first conveying member after the leading edge reaches the third position and before the trailing edge passes the first position when it is determined that the length exceeds the specific distance; Including, In the first drive control step, a timing to stop driving the first conveying member is determined based on an elapsed time from when the leading edge is detected by the detection unit, In the first drive control step, when it is determined that the length is equal to or shorter than the specific distance, when an elapsed time from when the detection unit detected the leading end exceeds a first reference time that is longer than a transport time of the sheet from the fourth position to the second position by the first transport member, driving of the first transport member is stopped, The sheet conveying method includes: a second drive control step of starting to drive the second conveying member when an elapsed time from when the leading edge is detected by the detection unit exceeds the first reference time, In the second drive control step, when a transport mode of the sheet is a predetermined specific mode, driving of the second transport member is started when an elapsed time from when the leading edge is detected by the detection unit exceeds the first reference time, and when the transport mode is not the specific mode, driving of the second transport member is started before the leading edge reaches the second position. In the first drive control step, if it is determined that the length is equal to or less than the specific distance and the transport mode is not the specific mode, the drive of the first transport member is stopped when the elapsed time from when the detection unit detects the leading edge exceeds a second reference time that is longer than the transport time.

Images