Sheet conveyance device, image reading device, and image forming device

Abstract

The present invention enables execution of more appropriate control in accordance with the state of a sheet.　A sheet conveyance device (20) comprises: a stacking unit (21) in which sheets are stacked; a feeding means (22, 23, 24) that separates and feeds the sheets stacked in the stacking unit (21) one by one; a detection means (S20) that detects flipping-up of a sheet fed by the feeding means (22, 23, 24); and a control means (81) that stops the feeding of the sheet on the basis of the detection of the flipping-up of the sheet by the detection means (S20) before the sheet is conveyed by a predetermined distance after the start of the feeding of the sheet by the feeding means (22, 23, 24), and allows the feeding of the sheet to continue regardless of the result of detection by the detection means (S20) after the sheet has been conveyed by the predetermined distance since the start of the feeding of the sheet by the feeding means (22, 23, 24).

Description

Sheet conveying device, image reading device, and image forming device

[0001] The present disclosure relates to a sheet conveying device that conveys a sheet, an image reading device that reads image information from a sheet, and an image forming apparatus that forms an image on a recording material.

[0002] Patent document 1 describes a method of determining whether a document is a folded document folded in a Z-shape or a bound bundle of documents based on the time and number of times a detection unit located above the document loading surface detects the document floating up.

[0003] Japanese Patent Application Laid-Open No. 2017-222511

[0004] When conveying a sheet with a crease, if the detection means detects that the sheet has jumped up, it may be mistakenly detected as a bound sheet, resulting in inappropriate control not being performed.

[0005] The present disclosure provides a sheet conveying device, an image reading device, and an image forming device that are capable of performing more appropriate control depending on the state of a sheet.

[0006] One aspect of the present disclosure is a sheet conveying device that includes a stacking section on which sheets are stacked, a feeding means that separates and feeds the sheets stacked on the stacking section one by one, a detection means that detects a jumping up of the sheet fed by the feeding means, and a control means that stops the feeding of the sheet based on the detection of the jumping up of the sheet by the detection means before the sheet is transported a predetermined distance from the start of feeding of the sheet by the feeding means, and allows the feeding of the sheet to continue regardless of the detection result of the detection means after the sheet has been transported the predetermined distance from the start of feeding of the sheet by the feeding means.

[0007] Another aspect of the present disclosure is a sheet conveying device comprising: a stacking section on which sheets are stacked; a feeding means for separating and feeding the sheets stacked on the stacking section one by one; a detection means for detecting any bouncing of the sheets fed by the feeding means; a display means for displaying information; and a control means for, if the detection means detects any bouncing of the sheets before the sheets have been transported a predetermined distance from the start of feeding of the sheets by the feeding means, not causing the display means to display a message urging the user to reduce the amount of bouncing of the sheets when resetting the sheets in the stacking section, and, if the detection means detects any bouncing of the sheets after the sheets have been transported the predetermined distance from the start of feeding of the sheets by the feeding means, causing the display means to display the message.

[0008] According to the present disclosure, it is possible to provide a sheet conveying device, an image reading device, and an image forming device that are capable of performing more appropriate control depending on the state of a sheet.

[0009] Other features and advantages of the present disclosure will become apparent from the following description taken in conjunction with the accompanying drawings, in which the same or similar components are designated by the same reference numerals.

[0010] Schematic diagram of a printer. Perspective view of an image reading device. Control block diagram. Example of a setting screen of a display panel. Top view showing the position of a skew detection sensor. Perspective view showing the position of a jump-up detection sensor. Explanatory diagram showing the behavior of a bound document. Explanatory diagram showing the behavior of a bound document. Explanatory diagram showing the behavior of a bound document. Explanatory diagram showing the behavior of an unbound document. Explanatory diagram showing the behavior of an unbound document. Explanatory diagram showing the behavior of a bound document. Explanatory diagram showing the behavior of a bound document. Explanatory diagram showing the behavior of a folded document. Flowchart of a document transport operation according to the first embodiment. Flowchart of a jump-up detection process according to the first embodiment. Explanatory diagram showing the behavior of a bound document. Explanatory diagram showing the behavior of a bound document. Flowchart of a document transport operation according to the second embodiment. Flowchart of a skew detection process according to the second embodiment. Flowchart of a document transport operation according to the third embodiment. Flowchart of a jump-up detection process according to the third embodiment. Example of a screen display according to the third embodiment. Example of a screen display according to the third embodiment.

[0011] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

[0012] First Embodiment First, an image forming apparatus according to the first embodiment will be described. FIG. 1 is a schematic cross-sectional view of a printer 100 as an image forming apparatus according to this embodiment. The printer 100 is an electrophotographic laser beam printer. The printer 100 includes a printer main body 70 and an image reading device 10 attached to the top of the printer main body 70. The printer 100 also includes an operation unit 506 that accepts operations from a user. The operation unit 506 is provided with a display panel 506a that serves as a display unit that displays information to the user. The display panel 506a is a touch panel that the user can operate by touching it with their fingers. In other words, the display panel 506a also functions as an input unit that accepts input from the user. The operation unit 506 may include hard keys such as a numeric keypad and an execute button as an input unit.

[0013] In the following description, the side of printer 100 where operation unit 506 is provided will be referred to as the front side, and the opposite side will be referred to as the rear side. That is, Fig. 1 is a diagram of printer 100 as seen from the front side. In this embodiment, the term "sheet" refers to not only plain paper, but also special paper such as coated paper, recording materials in special shapes such as envelopes and index paper, and plastic film or cloth for overhead projectors, and a document is also an example of a sheet.

[0014] The printer main body 70 has an image forming engine 60 as an image forming means. The image forming engine 60 includes an electrophotographic image forming unit PU and a fixing device 7. When a command to start an image forming operation is received, a photosensitive drum 1, which is a photosensitive member, rotates, and the drum surface is uniformly charged by a charging device 2. An exposure device 3 then modulates and outputs laser light based on image data transmitted from an image reading device 10 or an external computer, and scans the surface of the photosensitive drum 1 to form an electrostatic latent image. This electrostatic latent image is visualized (developed) into a toner image by toner supplied from a developing device 4.

[0015] In parallel with this image forming operation, a feeding operation is performed to feed a sheet S loaded on a cassette 9 or a manual feed tray (not shown) toward the image forming engine 60. The fed sheet S is transported in accordance with the progress of the image forming operation by the image forming unit PU. The toner image carried on the photosensitive drum 1 is then transferred onto the sheet S by a transfer roller 5. Any toner remaining on the photosensitive drum 1 after the toner image transfer is collected by a cleaning device 6. The sheet S onto which the unfixed toner image has been transferred is handed over to a fixing device 7, where it is sandwiched between a pair of rollers and heated and pressurized. The sheet S onto which the toner has been fixed is discharged to a discharge tray 71.

[0016] [Image Reading Device] Next, the image reading device 10 will be described. Fig. 2 is a perspective view of the image reading device 10. As shown in Figs. 1 and 2, the image reading device 10 includes an ADF 20 (Auto Document Feeder) as a sheet conveying device that conveys an original D, and a reading unit 40 as reading means that reads image information from the original conveyed by the ADF 20. The ADF 20 is rotatably supported with respect to the reading unit 40 by a hinge (not shown) so that a document table glass 41 can be opened. Note that the original D, which is an example of a sheet, may be blank paper or may have an image formed on one or both sides.

[0017] The ADF 20 has a document tray 21 as a loading section on which documents D are stacked, and an output tray 32 to which the documents D are discharged. The document tray 21 is provided with a first regulating plate 21a and a second regulating plate 21b as regulating means for regulating the widthwise position of the documents D set in the document tray 21. The first regulating plate 21a is located on the front side and abuts against the front edge of the documents D stacked on the document tray 21. The second regulating plate is located on the rear side and abuts against the rear edge of the documents D stacked on the document tray 21. The pair of regulating plates, the first regulating plate 21a and the second regulating plate 21b, are movable in the widthwise direction in conjunction with each other by an interlocking mechanism (not shown). Specifically, when one of the first regulating plate 21a and the second regulating plate 21b moves in the widthwise direction, the other of the first regulating plate 21a and the second regulating plate 21b moves in the opposite direction. The first and second regulating plates 21a and 21b come into contact with the ends of the document D in the width direction, thereby regulating the position of the document D.

[0018] The width direction is a direction (sheet width direction) perpendicular to the sheet transport direction in which the ADF 20 transports the document D. The width direction is, for example, the same direction as the rotation axis direction of the pickup roller 22 and the rotation axis direction of the feed roller 23. The sheet transport direction is the movement direction of the document D along the transport path from the document tray 21 to the discharge tray 32 via the reading position of the reading unit 40. In particular, the movement direction of the sheet S when the document D is fed from the document tray 21 into the main body of the ADF 20 may be referred to as the sheet feed direction.

[0019] The ADF 20 includes a pickup roller 22, a feed roller 23, a separation roller 24, a conveying roller pair 25, a lead roller pair 26, a lead roller pair 30, and a discharge roller pair 31. The feed unit consisting of the pickup roller 22, the feed roller 23, and the separation roller 24 constitutes the feeding means in this embodiment. Note that this feed unit is an example of the feeding means, and for example, a rotatable belt-like conveying member may be used instead of the pickup roller 22 and the feed roller 23. Furthermore, the separation roller 24 is an example of a separating member, and a pad-like separating member (separation pad) having a friction member may be used.

[0020] The ADF 20 also has a document presence / absence sensor S31 that detects the presence or absence of a document D on the document tray 21, and a first skew detection sensor S11 and a second skew detection sensor S12 that constitute a skew detection unit S10 as detection means (skew detection means) that detects skew of the document D. The first skew detection sensor S11 is an example of a first sensor, and the second skew detection sensor S12 is an example of a second sensor.

[0021] The ADF 20 also has a jump-up detection sensor S20 as a detection unit (jump-up detection unit) that detects jump-up of a document. The jump-up of a document refers to the vertical position of the document D at the detection position of the jump-up detection sensor S20 changing upward beyond a predetermined position when the document D is being fed. As will be described later, the jump-up of the document D occurs when the document D is a stapled document stack (bound document) or when the document D has a crease. The jump-up of a document may occur not only when the document D is deformed during feeding, but also when the document D is deformed so that a portion of the document D is raised upward when it is set on the document tray 21.

[0022] The jump-up detection sensor S20 of this embodiment is an optical sensor having a light-emitting unit S21 and a light-receiving unit S22. The light-emitting unit S21 emits detection light. The light-receiving unit S22 emits a signal corresponding to the incident detection light. The light-receiving unit S22 is positioned so that the detection light from the light-emitting unit S21 enters the sensor via an optical path passing above the document tray 21 (loading unit). The jump-up detection sensor S20 detects the jump-up of the document D when the optical path is blocked. The detection position of the jump-up detection sensor S20 in this embodiment is the position of the optical path from the light-emitting unit S21 to the light-receiving unit S22. In other words, the jump-up detection sensor S20 is configured so that the signal of the light-receiving unit S22 changes depending on whether the document D has jumped up, and the CPU 81 ( FIG. 3 ) can determine whether the document D has jumped up based on the signal received from the light-receiving unit S22. The predetermined position in this embodiment can be said to be the height of the optical path from the light-emitting unit S21 to the light-receiving unit S22.

[0023] The reading unit 40 has a flow reading glass 28, a jump table 29, a reference white board 42, a document glass table 41, a first mirror table 43, a second mirror table 44, a lens 45, and a CCD line sensor 46. A lamp 47 and a mirror 48 are disposed inside the first mirror table 43. Mirrors 49 and 50 are disposed inside the second mirror table 44. The first mirror table 43 and the second mirror table 44 are configured to be movable in the sub-scanning direction (left and right direction in the figure) by wires and drive motors (not shown).

[0024] The image reading device 10 can operate in a flow reading mode in which an image of an original D loaded on the original tray 21 is read while the original D is being fed by the ADF 20, and a fixed reading mode in which an image of an original placed on the original platen glass 41 is read. The flow reading mode is selected when the original presence / absence sensor S31 detects an original D loaded on the original tray 21, or when the flow reading mode is explicitly instructed by the operation unit 506.

[0025] When the skimming mode is executed, the pickup roller 22 supported by an arm (not shown) descends and rotates while abutting against the topmost document D on the document tray 21. The document D is then fed by the pickup roller 22 and separated one by one at a separation nip formed by the feed roller 23 and the separation roller 24. The feed roller 23 is made of a material such as rubber that has less friction than the separation roller 24. A torque limiter is disposed in the drive transmission path to the separation roller 24, so that the separation roller 24 rotates together with the feed roller 23 when one document is fed, but does not rotate when two or more documents are fed. This allows the document to be separated one by one by the feed roller 23 and the separation roller 24.

[0026] The document D fed from the document tray 21 is transported by a transport roller pair 25 and then transported toward the flow reading glass 28 by a lead roller pair 26. A platen guide roller 27 is disposed opposite the flow reading glass 28. The platen guide roller 27 guides the document D passing over the flow reading glass 28 so that the document D does not lift off the flow reading glass 28.

[0027] Then, as the original D passes through a reading position opposite the flow reading glass 28, the image on the surface of the original D is read by the reading unit 40 through the flow reading glass 28. Specifically, light from a lamp 47 is irradiated onto the original D being transported, and reflected light from the original D is guided to a lens 45 by mirrors 48, 49, and 50. The light that passes through the lens 45 forms an image on the light receiving section of a CCD line sensor 46, undergoes photoelectric conversion, and transmits the image information to the CPU 81. The reference white board 42 serves as a reference for the reading brightness of the original D. The original D that has passed through the flow reading glass 28 is guided by a jump platform 29 to a pair of read rollers 30, and is discharged to a discharge tray 32 by a pair of discharge rollers 31.

[0028] On the other hand, the fixed reading mode is selected when the reading unit 40 detects an original D placed on the original table glass 41, or when the fixed reading mode is explicitly instructed by the operation unit 506. In the fixed reading mode, the first mirror table 43 and the second mirror table 44 move along the original table glass 41, and scan the original D with light emitted by the lamp 47. Image information photoelectrically converted by the light receiving elements of the CCD line sensor 46 is transferred to the CPU 81.

[0029] In the present embodiment, the reading unit 40 has been described as having a CCD-type reading mechanism, but the reading unit 40 may also have a CIS (contact image sensor)-type reading mechanism. A CIS-type reading mechanism is composed of a lens array (life-size optical system) arranged in the main scanning direction, a CMOS image sensor arranged in the main scanning direction so as to face the original D via the lens array, and a light source that irradiates light onto the original D. Also, a CCD-type or CIS-type reading mechanism may be disposed inside the ADF 20. When reading mechanisms are disposed in both the ADF 20 and the reading unit 40, the image reading device 10 can read image information from both sides of the original D in a single skimming operation.

[0030] [Control Block] FIG. 3 is a control block diagram of the CPU 81 serving as a control unit. The CPU 81 is connected to a first skew detection sensor S11 and a second skew detection sensor S12 (skew detection unit S10), a light-emitting unit S21 and a light-receiving unit S22 (jump-up detection sensor S20), and a document presence / absence sensor S31. The CPU 81 is also connected to a feed motor 84 and a transport motor 85 via a motor control unit 83. The feed motor 84 drives the pickup roller 22 and the feed roller 23. The transport motor 85 drives the transport roller pair 25, the read roller pair 26, the read roller pair 30, and the discharge roller pair 31. The CPU 81 is also connected to an operation unit 506 and a memory unit 507. A user can start an image reading operation (image reading job) and perform various settings by operating the operation unit 506.

[0031] In this embodiment, the second skew detection sensor S12 also serves as a post-separation sensor for determining the timing to start feeding the document. Specifically, the CPU 81 starts feeding the subsequent sheet following the preceding sheet based on the second skew detection sensor S12 detecting the trailing edge of the preceding sheet. In this way, by having the second skew detection sensor S12 also serve as a post-separation sensor, the number of sensors can be reduced, thereby reducing product costs. However, the post-separation sensor may be disposed separately from the skew detection unit S10. Furthermore, the skew detection unit S10 may be disposed downstream in the sheet conveyance direction from the post-separation sensor disposed downstream and near the separation nip.

[0032] The CPU 81 reads and executes programs stored in the storage unit 507 to control the operation of the ADF 20 or the operation of the image reading device 10, which will be described below. The CPU 81 is disposed, for example, on a control board mounted in the housing of the reading unit 40, and is communicably connected to the control unit of the printer main body 70. The CPU 81 may be disposed in the ADF 20. Furthermore, some or all of the processing performed by the CPU 81, which will be described below, may be executed by the control unit of the printer main body 70.

[0033] 4 shows one example of a screen displayed on the display panel 506a of the operation unit 506, which allows the user to set the execution conditions for the image reading operation by the image reading device 10. In other words, the operation unit 506 is an example of a setting unit for setting the execution conditions for the image reading operation.

[0034] 4 displays a read start button 600 for instructing the start of image reading operation, multiple buttons 601 for setting various conditions for image reading, and a button 602 for setting bound document detection. Here, a "bound document" refers to a document stack (sheet stack) consisting of multiple stapled sheets of document D.

[0035] When the user presses the read start button 600, the image reading device 10 starts an image reading operation (image reading job) that reads image information from a document, which is a series of operations including a document transport operation. Note that if the screen of Fig. 4 is displayed when setting a copy job that duplicates an image of document D, pressing the read start button 600 (copy start button) causes the image reading operation in the image reading device 10 and the image forming operation in the printer main body 70 to be executed.

[0036] [Skew Detection Sensor] Next, the first skew detection sensor S11 and the second skew detection sensor S12 will be described. FIG. 5 is a top view showing the positions of the first skew detection sensor S11 and the second skew detection sensor S12. The first skew detection sensor S11 and the second skew detection sensor S12 are disposed downstream of the feed roller 23 in the sheet transport direction (sheet feed direction). The first skew detection sensor S11 and the second skew detection sensor S12 are disposed side by side in the width direction. That is, the first skew detection sensor S11 and the second skew detection sensor S12 are disposed at the same position in the sheet transport direction. Note that although there are two skew detection sensors in this embodiment, the number of skew detection sensors may be three or more.

[0037] The CPU 81 can determine whether the document being fed is skewed or not based on signals from the first skew detection sensor S11 and the second skew detection sensor S12. Furthermore, if the document is significantly skewed, the CPU 81 may determine that the document is stapled (that the document is a bound document).

[0038] The CPU 81 determines that the document is skewed when the first skew detection sensor S11 or the second skew detection sensor S12 does not detect the document within a predetermined time after the other of the first skew detection sensor S11 and the second skew detection sensor S12 detects the document. If the CPU 81 determines that the document is skewed, it stops feeding the document. In other words, the CPU 81 stops feeding when there is a large difference in the detection timing between the first skew detection sensor S11 and the second skew detection sensor S12. The skew detection process executed by the CPU 81 will be described later.

[0039] [Jump-up Detection Sensor] Next, the jump-up detection sensor S20 will be described. As shown in FIG. 2 , the ADF 20 has a first wall portion 33 and a second wall portion 34 that extend perpendicularly to the support surface 21s that supports the originals on the original tray 21. The first wall portion 33 and the second wall portion 34 are a pair of walls that are arranged opposite each other across the support surface of the original tray 21. The first wall portion 33 is arranged closer to the front than the first restricting plate 21a, and the second wall portion 34 is arranged closer to the back than the second restricting plate 21b. The light-emitting unit S21 is arranged on the first wall portion 33, and the light-receiving unit S22 is arranged on the second wall portion. That is, the light-emitting unit S21 and the light-receiving unit S22 are arranged at a distance from each other in the width direction on the support surface 21s of the original tray 21, sandwiching a document set area therebetween. The document set area is the area that is covered by a document when a document of the maximum size that can be set in the document tray 21 is set in the width direction.

[0040] 6 is a perspective view showing the position of the jump-up detection sensor S20. The position of the jump-up detection sensor S20 is based on the position of the optical path from the light-emitting unit S21 to the light-receiving unit S22. As shown in FIG. 6, the jump-up detection sensor S20 is disposed vertically above the support surface 21s of the document tray 21 (stacking unit). The jump-up detection sensor S20 is also disposed upstream of the separation nip formed by the feed roller 23 and the separation roller 24 in the sheet transport direction. In this embodiment, the position (detection position) of the jump-up detection sensor S20 is set upstream of the pickup roller 22 in the sheet feed direction.

[0041] The position (detection position) of the bounce detection sensor S20 is set, for example, at a position where the distance from the reference position of the leading edge of the document D in the document tray 21 in the sheet feed direction is less than 210 mm. In other words, the distance in the sheet feed direction from the reference position of the leading edge of the document (sheet) in the document tray 21 (loading section) to the detection position is less than 210 mm. The reference position is downstream of the pickup roller 22 and upstream of the separation nip in the sheet feed direction, and is, for example, a position where the leading edge of the document D abuts against a retractable shutter member during feeding. This configuration allows for appropriate detection of the bounce of a bound document even when A3-sized Z-folded documents are set in the document tray 21 in the long-edge feed orientation. However, the position (detection position) of the bounce detection sensor S20 can be changed depending on the document size (particularly the maximum size) supported by the document tray 21. Furthermore, to accommodate a wider variety of sheet sizes, multiple bounce detection sensors may be arranged at different positions in the sheet feed direction.

[0042] The CPU 81 can determine whether or not the document D has jumped up based on a signal from the light receiving unit S22. When the optical path from the light emitting unit S21 to the light receiving unit S22 is blocked by the document, the CPU 81 may determine that the document is a bound document and stop feeding, for example. The process of the jumping up detection executed by the CPU 81 will be described later.

[0043] [Document Conveyance Operation Flow] Next, the control of document conveyance by the ADF 20 will be described with reference to a flowchart. Fig. 11 is a flowchart showing the process of the document conveyance operation executed by the CPU 81. When the power to the printer 100 is turned on, the CPU 81 starts the process of the flowchart in Fig. 11. Note that the flow in Fig. 11 describes the operation when skew of the document is not detected as a result of skew detection by the first skew detection sensor S11 and the second skew detection sensor S12.

[0044] First, the CPU 81 determines whether or not a document has been set on the document tray 21 based on a signal from the document presence / absence sensor S31 (S101). If no document is present on the document tray 21 (S101: No), the CPU 81 does not proceed to the next process and waits until a document is placed on the document tray 21.

[0045] If it is determined that originals are loaded on the original tray 21 (S101: Yes), the CPU 81 determines whether or not a feeding start command has been issued by the user (S102). The CPU 81 determines that a feeding start command has been issued when, for example, the user presses the reading start button 600 on the screen in Fig. 4. If a feeding start command has not been issued (S102: No), the CPU 81 does not proceed to the next process and waits until a feeding start command is issued.

[0046] If a feeding start command is received (S102: Yes), the CPU 81 starts feeding the originals (S103). Specifically, the CPU 81 starts driving the feeding units (22, 23, 24) using the feeding motor 84, and lowers the pickup roller 22 to contact the topmost original. Furthermore, if the original tray 21 (or a part thereof) can be raised and lowered, the CPU 81 raises the original tray 21 before lowering the pickup roller 22. Once feeding of the originals has started, the CPU 81 starts a jump-up detection process (S104). The jump-up detection process will be described later.

[0047] The CPU 81 determines whether a jumping-up document has been detected in the jumping-up detection process (S105). If a jumping-up document has been detected (S105: Yes), the CPU 81 stops the feed motor 84 and the transport motor 85 to stop the transport of the document (S106). Furthermore, if a jumping-up document has been detected, the CPU 81 displays a message on the display panel 506a indicating that the document may be stapled (may be a bound document) (S107). This message may be, for example, message M0 or M3 shown in FIG. 18A of the third embodiment. Additionally, together with the message, buttons (FIGS. 18A and 18B) that allow the user to select a solution may be displayed.

[0048] If no jumping of the document is detected in the jumping detection process (S105: No), the CPU 81 determines that the document transport can continue (S108). In other words, in S108, the CPU 81 allows the document (sheet) feeding to continue. In this case, the CPU 81 controls the drive of the feed motor 84 and the transport motor 85 according to a predetermined transport schedule to continue the document transport. Even if the CPU 81 determines that the document transport can continue in S108, the CPU 81 may stop the document transport if a document transport abnormality is detected. A transport abnormality is, for example, a document stuck or delayed on the document transport path in the ADF 20 (collectively referred to as a jam). The CPU 81 controls the document transport while monitoring for jams and other transport abnormalities based on the detection results of various sensors (e.g., the second skew detection sensor S12 as a post-separation sensor) arranged on the document transport path.

[0049] Thereafter, the CPU 81 determines whether the document being transported is the last document based on a signal from the document presence / absence sensor S31 (S109). If the document being transported is the last document (S109: Yes), the CPU 81 stops the feed motor 84 and the transport motor 85 to stop transport of the document (S110). If the document being transported is not the last document (S109: No), the CPU 81 returns to S103 and starts feeding the next document. The CPU 81 repeats the above process, and when transport of the last document is completed, the process of the flowchart ends.

[0050] [Jump-up Detection Method] Next, before describing the jump-up detection process executed in S105, the movement of the document when jumping up will be described. In the following description, a state in which the light-receiving unit S22 receives light from the light-emitting unit S21 of the jump-up detection sensor S20 will be referred to as the "non-detection state" of the jump-up detection sensor S20. A state in which the light-receiving unit S22 does not receive light from the light-emitting unit S21 will be referred to as the "detection state" of the jump-up detection sensor S20. The detection state is a state in which the jump-up detection sensor S20 detects a jump-up of the document, and the non-detection state is a state in which the jump-up detection sensor S20 does not detect a jump-up of the document.

[0051] 7A to 7C are perspective views showing the movement of the bound document Dst when it is fed. FIG. 7A shows the state in which the bound document Dst is stacked, FIG. 7B shows the state in which the bound document Dst has been fed up to the feed roller 23, and FIG. 7C shows the state in which the bound document Dst has jumped up. Note that the bound document Dst is a stack of documents in which the first document Dst1 and the second document Dst2 are bound together with staples ST. Also, FIGS. 8A and 8B are perspective views showing the movement of the document when an unstapled document D is fed. FIG. 8A shows the state in which the document D is being transported, and FIG. 8B shows the state in which the trailing edge of the transported document D has passed the second skew detection sensor S12.

[0052] When feeding is started with bound documents Dst stacked on document tray 21 as shown in Fig. 7A, the bound documents Dst are transported by pickup roller 22 to the separation nip formed by feed roller 23 and separation roller 24. When the bound documents Dst reach the separation nip as shown in Fig. 7B, the first document Dst1 and the second document Dst2 are transported so as to be separated. At this time, the first document Dst1 advances in the sheet transport direction and passes through the separation nip, while the second document Dst2 is prevented from passing through the separation nip by separation roller 24 and remains on document tray 21. However, because the first document Dst1 and the second document Dst2 are bound together by staples ST, the force applied by each roller may cause the first document Dst1 to jump up.

[0053] 7C, when the first document Dst1 jumps up, the first document Dst1 blocks the optical path from the light-emitting element S21 to the light-receiving element S22, and the light from the light-emitting element S21 does not reach the light-receiving element S22. That is, the jump-up detection sensor S20 switches from a non-detecting state to a detecting state. When the jump-up detection sensor S20 enters the detecting state, the CPU 81 can determine that a document has jumped up.

[0054] On the other hand, when an unstapled document D is transported as shown in Fig. 8A, the jump-up detection sensor S20 is in a non-detecting state. Then, as shown in Fig. 8B, the trailing edge of the document D passes the second skew detection sensor S12, which also serves as a post-separation sensor, while the jump-up detection sensor S20 remains in a non-detecting state. When the document D passes the second skew detection sensor S12 without being detected as jumping up, the CPU 81 can determine that the next document D can be fed (allowing feeding to begin).

[0055] 9A to 9C are perspective views showing the movement of the bound document Dst when the document is fed with its trailing edge stapled. Fig. 9A shows the state in which the bound document Dst is stacked, Fig. 9B shows the state in which the bound document Dst has been fed up to the feed roller 23, and Fig. 9C shows the state in which the bound document Dst has jumped up. While Figs. 7A to 7C illustrate the case in which the leading edge of the bound document Dst is stapled, Figs. 9A to 9C explain the case in which the trailing edge of the bound document Dst is stapled. The leading edge of the document or bound document refers to the downstream edge of the document or bound document in the sheet transport direction, and the trailing edge of the document or bound document refers to the upstream edge of the document or bound document in the sheet transport direction.

[0056] When bound originals Dst with their trailing edges stapled are fed as shown in FIG. 9A, the bound originals Dst are transported to the feed roller 23 without jumping up, as shown in FIG. 9B. However, while the first original Dst1 advances in the sheet transport direction and passes through the separation nip, the second original Dst2 is prevented from passing through the separation nip by the separation roller 24 and remains in the original tray 21. As a result, the stapled trailing edge of the bound original Dst jumps up. This causes the optical path from the light-emitting unit S21 to the light-receiving unit S22 to be blocked by the bound original Dst, and the jump-up detection sensor S20 enters a detection state. In this way, even if the position of the staple ST is different, the CPU 81 can detect the jump-up of the original.

[0057] [Detection of Jumping Up Due to Folded Document] The above has described the detection of jumping up of a stapled bound document Dst when it is conveyed, but if the document D is a folded document, jumping up may be detected even if it is a single document that is not stapled. A folded document (folded sheet) is a document (sheet) that does not lie completely flat even when placed on a flat surface such as a desk due to a crease (fold line), such as a document that has been filed in a Z-fold (one-side fold).

[0058] 10 is a diagram showing an example of a folded document Df that has been folded in a Z-shape at two folds, a valley fold Dv and a mountain fold Dp, and is set in the document tray 21 with the mountain fold Dp at the rear end. As shown in FIG. 10, the folded document Df may be set with a fold remaining so that the mountain fold Dp protrudes upward relative to the leading end of the valley fold Dv.

[0059] When using a folded original Df, if the folded original Df is set in the original tray 21 in a flattened state so that the height of the mountain fold Dp is sufficiently low, the image reading device 10 can normally convey the folded original Df. However, if the folded original Df is set in an insufficiently flattened state, the jump-up detection sensor S20 will detect the jump-up of the original when the protruding portion of the folded original Df passes through the jump-up detection sensor S20 after feeding begins. Specifically, in the case of a folded original Df that has been Z-folded as shown in Figure 10, the portion between the valley fold Dv and the mountain fold Dp of the folded original Df blocks the light path from the light-emitting unit S21 to the light-receiving unit S22, causing the jump-up detection sensor S20 to change from a non-detecting state to a detecting state.

[0060] 10 shows a Z-folded folded document Df, but the document may also be detected as jumping up if the document is folded in a manner other than the Z-fold, such as in half (center fold) or in thirds. In other words, regardless of the folding method, if a folded document is set in the document tray 21 with part of the document protruding upward due to a fold, the jumping up of the document will be detected by the jumping up detection sensor S20 after feeding of the folded document begins.

[0061] Therefore, in this embodiment, as will be described below, the control content of the jump-up detection sensor S20 is changed depending on the transport distance from the start of feeding the document, thereby making it possible to deal more appropriately with folded documents.

[0062] [Jump-up Detection Process] The jump-up detection process will be described below. FIG. 12 is a flowchart showing the processing of the jump-up detection process executed by the CPU 81. When the jump-up detection process starts, the CPU 81 determines whether the jump-up detection sensor S20 is in a detection state (S201). If the jump-up detection sensor S20 is in a non-detection state (S201: No), the CPU 81 determines whether the document has been transported a predetermined distance since the start of document feeding (S203). If the document has not been transported a predetermined distance since the start of document feeding (S203: No), the process returns to S201. In other words, the CPU 81 monitors whether the jump-up detection sensor S20 is in a detection state between the start of document feeding and the time the document has been transported a predetermined distance.

[0063] The start of document feeding refers to the point in time when pickup roller 22 comes into contact with the document to be fed this time (the topmost document on document tray 21) and is being rotated (S103 in FIG. 11). That is, document feeding starts when pickup roller 22, which is stationary, comes into contact with the document and then pickup roller 22 begins to be rotated by feed motor 84, or when pickup roller 22, which is being rotated, descends and comes into contact with the document. Furthermore, CPU 81 can calculate the document transport distance from the start of document feeding based on the elapsed time from the start of document feeding and the document transport speed. The document transport speed may be, for example, the circumferential speed of pickup roller 22.

[0064] The "predetermined distance" is a threshold value for distinguishing between the range of transport distances in which the document is detected to bounce up because it is a bound document and the range of transport distances in which the document is detected to bounce up because it is a folded document.

[0065] In the case of a bound document, the first document Dst jumps up in accordance with the relative movement between the first document Dst1 and the second document Dst2, so the jumping up of the document is detected a relatively short transport distance after the document feed begins. In contrast, if the document is a folded document, the jumping up of the document is not detected until the portion of the folded document that protrudes upward due to the fold reaches the detection position of the jumping up detection sensor S20. Therefore, although it depends on the folding method, in the case of a folded document, the jumping up of the document is not detected until the document has been transported a relatively long transport distance after the document feed begins. For example, in the case of the Z-folded folded document Df in Figure 10, the jumping up is not detected until the portion extending upward from the valley fold Dv toward the mountain fold Dp passes the jumping up detection sensor S20, and the jumping up is detected when that portion passes the jumping up detection sensor S20.

[0066] The value of the predetermined distance is set to, for example, a value equal to or less than half the length of the document in the sheet transport direction (sheet feed direction). This is because a typical example of a folded document Df is a Z-folded document. On the other hand, if the predetermined distance is too short, it will affect the detection of a bound document, so the value of the predetermined distance is set to, for example, at least one-quarter or one-third of the length of the document in the sheet transport direction (sheet feed direction).

[0067] The value of the predetermined distance can be changed depending on the length of the document set in the document tray 21. The CPU 81 acquires the length of the document set in the document tray 21 based on information input by the user via the operation unit 506 and information from a sensor arranged in the document tray 21, and determines the value of the predetermined distance based on the acquired length of the document. The sensor arranged in the document tray 21 is, for example, a sensor that has a flag protruding above the support surface 21s of the document tray 21 and can determine whether the length of the document is equal to or greater than a specific length by detecting that the flag has been pressed against a sheet.

[0068] If the jump-up detection sensor S20 enters a detection state before the document has been transported a predetermined distance from the start of feeding (S201: Yes), the CPU 81 determines that the document has jumped up and sets the result of the jump-up detection process to "jump-up occurred" (S202). The result of the jump-up detection process is recorded in the storage unit 507, for example, and is referenced in the flow of the document transport operation (FIG. 11).

[0069] On the other hand, if the document is transported a predetermined distance from the start of feeding while the jump-up detection sensor S20 remains in a non-detecting state (S203: Yes), the CPU 81 disables the document jump-up detection function (S204).The CPU 81 also determines that the document has not jumped up, and sets the result of the jump-up detection process to "no jump-up" (S205).

[0070] In disabling the jump-up detection function (S204), the CPU 81 disables (stops) the jump-up detection sensor S20 itself, for example. Specifically, the CPU 81 stops the light emission from the light-emitting unit S21 and does not accept signals from the light-receiving unit S22.

[0071] If the result of the jump-up detection process is "jump-up occurred," the CPU 81 stops the transport of the document (S106), as in the flow of the document transport operation described above (FIG. 11). On the other hand, if the result of the jump-up detection process is "no jump-up," the CPU 81 determines that the transport of the document can be continued (S105: No, S108), as in the flow of the document transport operation described above (FIG. 11).

[0072] In this embodiment, if the jump-up detection sensor S20 enters a detection state before the document has been transported a predetermined distance from the start of document feeding, the CPU 81 stops the transport of the document (S106) regardless of the length of time the jump-up detection sensor S20 remains in the detection state. Also, in this embodiment, if the jump-up detection sensor S20 enters a detection state before the document has been transported a predetermined distance from the start of document feeding, the CPU 81 stops the transport of the document (S106) regardless of the number of times the jump-up detection sensor S20 enters the detection state.

[0073] [Summary of the Present Embodiment] As described above, the CPU 81 of the present embodiment stops the transport of the original document (S106) based on the detection of the jumping-up detection sensor S20 of the original document jumping up (S201: Yes) before the original document has been transported a predetermined distance from the start of feeding of the original document by the feeding units (22, 23, 24) (S203: No). Furthermore, after the original document has been transported a predetermined distance from the start of feeding of the original document by the feeding units (22, 23, 24) (S203: Yes), the CPU 81 determines that the transport of the original document can be continued regardless of the detection state / non-detection state of the jumping-up detection sensor S20 (S108).

[0074] In other words, the control unit of this embodiment stops the sheet feeding based on the detection unit's detection of the sheet jumping up before the sheet is transported a predetermined distance from the start of sheet feeding by the feeding unit, and allows the sheet feeding to continue regardless of the detection result of the detection unit after the sheet is transported a predetermined distance from the start of sheet feeding by the feeding unit.

[0075] According to this configuration, when a folded document is set in the document tray 21 ( FIG. 10 ), the protruding portion of the folded document passes the jump-up detection sensor S20 after the document has been transported a predetermined distance from the start of document feeding, allowing the ADF 20 to continue transporting the folded document. As a comparative example, a configuration is conceivable in which, even if the jump-up detection sensor S20 enters a detection state after the document has been transported a predetermined distance during the jump-up detection process, a "jump-up occurrence" is detected and document transport is stopped. In this comparative example, document transport may be stopped even though the ADF 20 is actually capable of feeding the folded document. In contrast, according to this embodiment, the transport of the folded document can be continued, thereby improving usability.

[0076] On the other hand, when bound documents are set in the document tray 21 (FIGS. 7A to 7C, 9A to 9C), the bounce detection sensor S20 enters a detection state before the documents are transported a predetermined distance from the start of document feeding, and therefore transport of the bound documents is stopped. This makes it possible to avoid document damage or jams caused by forcibly transporting the bound documents.

[0077] Therefore, according to the present embodiment, it is possible to provide a sheet conveying device, an image reading device, and an image forming device that are capable of executing more appropriate control depending on the state of the sheet.

[0078] [Variation 1] In the flow of FIG. 12 , the document jump-up detection function is disabled (S204). Alternatively, the document jump-up detection sensor S20 itself may continue to detect the document, but the document transport may not be stopped even if the document jump-up detection sensor S20 detects the document jump-up. In this variation, the document jump-up detection sensor S20 continues to detect the document jump-up even after the document has been transported a predetermined distance from the start of feeding while the document jump-up detection sensor S20 remains in a non-detecting state (S203: Yes). Even if the CPU 81 receives a signal indicating that the document jump-up detection sensor S20 has changed from a non-detecting state to a detecting state after S203: Yes, the CPU 81 determines that document transport can continue (S108 in FIG. 11 ). This method also provides the same advantages as the first embodiment.

[0079] [Variation 2] In the first embodiment, when multiple documents are continuously fed from the document tray 21, the bounce detection function may be disabled in the gap between the documents (between the documents). For example, from the time when the trailing edge of a previously fed document passes the detection position of the bounce detection sensor S20 until the next document (subsequent sheet) passes the detection position of the bounce detection sensor S20, it may be determined that the previously fed document can be continued to be conveyed, regardless of whether the bounce detection sensor S20 is in a detecting state or a non-detecting state. This allows the ADF 20 to continue conveying the document even if the optical path from the light-emitting unit S21 to the light-receiving unit S22 is temporarily blocked by an object other than the document.

[0080] [Variation 3] In the first embodiment, for small-sized documents that do not require binding, the jump-up detection function may be disabled throughout the job. For example, in the document transport operation flow shown in FIG. 11 , the jump-up detection process (S104) may not be executed for small-sized documents, and the process may proceed assuming that there is no jump (S105: No). A small-sized document is, for example, a document whose length in the sheet feed direction is equal to or shorter than the long side of an A6 size document or a business card size document. This prevents the transport of small-sized documents from being stopped due to, for example, erroneous detection by the jump-up detection sensor S20.

[0081] In other words, when a sheet having a first length in the sheet feeding direction is conveyed, the control unit of this modified example executes a first mode in which the control unit stops sheet feeding based on the detection unit's detection of a jump of the sheet before the sheet has been conveyed a predetermined distance from the start of sheet feeding by the feeding unit, and allows sheet feeding to continue after the sheet has been conveyed a predetermined distance from the start of sheet feeding by the feeding unit, regardless of the detection result of the detection unit. Furthermore, when a sheet having a second length in the sheet feeding direction that is shorter than the first length is conveyed, the control unit of this modified example executes a second mode in which the control unit allows sheet feeding to continue regardless of the detection result of the detection unit before and after the sheet has been conveyed a predetermined distance from the start of sheet feeding by the feeding unit. An example of the first mode is a mode including S104, S105: Yes, and S106 in FIG. 11 , as described in the first embodiment. An example of the second mode is a mode in which S105 in the flow of FIG. 11 is always No.

[0082] Second Embodiment An image forming apparatus according to a second embodiment will be described. In this embodiment, an example of control in which skew detection by the skew detection unit S10 and jump-up detection by the jump-up detection sensor S20 are performed in parallel will be described. Below, elements with the same reference numerals as those in the first embodiment will have basically the same configurations and functions as those described in the first embodiment unless otherwise specified, and differences from the first embodiment will be mainly described.

[0083] [Document Conveyance Operation Flow] Next, the control of document conveyance by the ADF 20 will be described with reference to a flowchart. Fig. 14 is a flowchart showing the process of the document conveyance operation executed by the CPU 81. When the printer 100 is powered on, the CPU 81 starts the process of the flowchart in Fig. 14.

[0084] First, the CPU 81 determines whether or not a document has been set on the document tray 21 based on a signal from the document presence / absence sensor S31 (S301). If no document is present on the document tray 21 (S301: No), the CPU 81 does not proceed to the next process and waits until a document is placed on the document tray 21.

[0085] When it is determined that originals are loaded on the original tray 21 (S301: Yes), the CPU 81 determines whether or not a user has instructed to start feeding (S302). When a user has not instructed to start feeding (S302: No), the CPU 81 does not proceed to the next process and waits until a user instructs to start feeding. When it is determined that a user instructs to start feeding has been instructed (S302: Yes), the CPU 81 starts feeding the originals (S303). When feeding of the originals starts, the CPU 81 starts a jump-up detection process (S304) and a skew detection process (S305). The jump-up detection process is the same as in the first embodiment, so a description thereof will be omitted. The skew detection process will be described later.

[0086] The CPU 81 determines whether skew of the document is detected in the skew detection process (S306) and whether jumping of the document is detected in the jumping detection process (S307). If skew or jumping of the document is detected (S306: Yes, S307: Yes), the CPU 81 stops the feed motor 84 and the transport motor 85 to stop the transport of the document (S308). The CPU 81 also displays a message on the display panel 506a indicating that the document may be stapled (S309). This message may be, for example, message M0 or M3 shown in FIG. 18A of the third embodiment. Additionally, buttons (FIGS. 18A and 18B) that allow the user to select a solution may be displayed together with the message.

[0087] If skew or jumping of the original document is not detected in the skew detection process or the jumping detection process (S306: No, S307: No), the CPU 81 determines that the transport of the original document can be continued (S310). In this case, the CPU 81 controls the drive of the feed motor 84 and the transport motor 85 in accordance with a predetermined transport schedule to continue the transport of the original document. Note that even if it is determined in S310 that the transport of the original document can be continued, the CPU 81 may stop the transport of the original document if an abnormality in the transport of the original document is detected.

[0088] Thereafter, the CPU 81 determines whether the document being transported is the last document based on a signal from the document presence / absence sensor S31 (S311). If the document being transported is the last document (S311: Yes), the CPU 81 stops the feed motor 84 and the transport motor 85 to stop transport of the document (S312). If the document being transported is not the last document (S311: No), the CPU 81 returns to S303 and starts feeding the next document. The CPU 81 repeats the above process, and when transport of the last document is completed, the process of the flowchart ends.

[0089] [Method for detecting skew] First, before describing the flowchart of the skew detection process, the movement of the document when skew occurs will be described. Figures 13A and 13B are perspective views showing the movement of the document when the bound document Dst is fed. Figure 13A shows a state in which the bound document Dst is stacked, and Figure 13B shows a state in which the bound document Dst is fed and skew occurs.

[0090] 13A, when feeding is started with the bound document Dst stacked on the document tray 21, the bound document Dst is conveyed by the pickup roller 22 to the separation nip formed by the feed roller 23 and the separation roller 24. When the bound document Dst reaches the separation nip as shown in FIG. 13B, the first document Dst1 and the second document Dst2 are conveyed so as to be separated.

[0091] The first document Dst1 advances in the sheet conveyance direction and passes through the separation nip, while the second document Dst2 is prevented from passing through the separation nip by the separation roller 24 and remains in the document tray 21. However, because the first document Dst1 and the second document Dst2 are stapled together with staples ST, the first document Dst1 may rotate around the staple ST. In this case, the side of the document Dst1 that is stapled with staples ST is not conveyed, so the first skew detection sensor S11 is turned OFF. On the other hand, the side of the document Dst1 that is not stapled with staples ST is conveyed downstream, so the second skew detection sensor S12 is turned ON.

[0092] In this way, the CPU 81 can determine whether the document is skewed based on the difference in timing at which the two skew detection sensors turn ON. Note that, although the reason why skew occurs when the document is a bound document Dst has been explained here, skew can also occur in documents that are not bound due to various causes such as improper setting position or roller wear. The skew detection unit S10 can detect skew of the document regardless of whether the document is a bound document Dst or not.

[0093] [Skew Detection Process] Next, the skew detection process (S305 in FIG. 14) will be described with reference to a flowchart. FIG. 15 is a flowchart showing the skew detection process executed by the CPU 81.

[0094] First, the CPU 81 waits until either the first skew detection sensor S11 or the second skew detection sensor S12 is turned ON (S401, S402).

[0095] If the second skew detection sensor S12 turns ON first (S402: Yes), the CPU 81 measures the time difference until the first skew detection sensor S11 turns ON (S403, S404). That is, if a predetermined time Tth [ms] has elapsed since the second skew detection sensor S12 turned ON while the first skew detection sensor S11 remains OFF (S404: Yes), the CPU 81 determines that skew has occurred (S405) and ends the skew detection process. On the other hand, if the first skew detection sensor S11 turns ON before the predetermined time Tth has elapsed since the second skew detection sensor S12 turned ON (S403: Yes), the CPU 81 determines that skew has not occurred (S409) and ends the skew detection process.

[0096] If the first skew detection sensor S11 turns ON first (S401: Yes), the CPU 81 measures the time difference until the second skew detection sensor S12 turns ON (S406, S407). That is, if a predetermined time Tth has elapsed since the first skew detection sensor S11 turned ON while the second skew detection sensor S12 remains OFF (S407: Yes), the CPU 81 determines that skew has occurred (S405) and ends the skew detection process. On the other hand, if the second skew detection sensor S12 turns ON before the predetermined time Tth has elapsed since the first skew detection sensor S11 turned ON (S406: Yes), the CPU 81 determines that skew has not occurred (S409) and ends the skew detection process.

[0097] Here, the predetermined time Tth is a value determined according to the document transport speed, etc., and is, for example, 30 ms. However, the value of the predetermined time Tth is not limited to this. Furthermore, the value of the predetermined time Tth may be different between S404 and S407.

[0098] Furthermore, in S405, the CPU 81 sets the result of the skew detection process to "skew present." Specifically, the CPU 81 records information indicating that skew of the original document has not occurred in the storage unit 507. In S406, the CPU 81 sets the result of the skew detection process to "skew absent." Specifically, the CPU 81 records information indicating that skew of the original document has not occurred in the storage unit 507.

[0099] The CPU 81 waits until the second skew detection sensor S12 turns OFF (S408) before proceeding to S409. If the predetermined time limit has elapsed while the second skew detection sensor S12 remains ON (S408: No), the CPU 81 may determine that a jam has occurred.

[0100] In this way, the skew detection unit S10 of this embodiment detects skew of the document based on the difference in the detection timing of the leading edge of the document by the first skew detection sensor S11 (first sensor) and the second skew detection sensor S12 (second sensor).

[0101] If the result of the skew detection process is "skew present," the CPU 81 stops the transport of the document (S308), as per the flow of the document transport operation described above (FIG. 14). On the other hand, if the result of the skew detection process is "no skew," and the result of the bounce detection process is "no bounce," as per the flow of the document transport operation described above (FIG. 14), the CPU 81 determines that the transport of the document can continue (S307: No, S310). However, if the result of the skew detection process is "no skew" and the result of the bounce detection process is "bounce present," the transport of the document is stopped (S307: Yes, S308).

[0102] [Summary of this embodiment] As in the first embodiment, the CPU 81 of this embodiment stops the transport of the original document (S308) based on the detection of the jump-up detection sensor S20 that the original document has jumped up (S201: Yes) before the original document has been transported a predetermined distance from the start of feeding of the original document (S203: No). Furthermore, after the original document has been transported a predetermined distance from the start of feeding of the original document (S203: Yes), the CPU 81 of this embodiment determines that the transport of the original document can be continued regardless of the detection state / non-detection state of the jump-up detection sensor S20 (S310).

[0103] Therefore, according to the present embodiment, it is possible to provide a sheet conveying device, an image reading device, and an image forming device that are capable of executing more appropriate control depending on the state of the sheet.

[0104] 15, in this embodiment, if the skew detection unit S10 detects skew in the original, the transport of the original is stopped regardless of whether the original has been transported a predetermined distance since the start of original feeding (S303). Therefore, even if the jump-up detection sensor S20 does not enter a detection state for some reason between the start of feeding of the bound original and the time the bound original has been transported a predetermined distance, the transport of the bound original is stopped based on the detection of skew in the original. This makes it possible to avoid damage to the original or jams caused by forcibly transporting the bound original.

[0105] Third Embodiment An image forming apparatus according to a third embodiment will be described. In this embodiment, the content of the display on the operation unit 506 is changed when a jump-up of the document is detected before or after the document has been transported a predetermined distance from the start of document feeding. Hereinafter, elements with the same reference numerals as those in the first embodiment will be assumed to have basically the same configurations and functions as those described in the first embodiment unless otherwise specified, and differences from the first embodiment will be mainly described.

[0106] [Document Conveyance Operation Flow] Next, the control of document conveyance by the ADF 20 will be described with reference to a flowchart. Fig. 16 is a flowchart showing the process of the document conveyance operation executed by the CPU 81. When the printer 100 is powered on, the CPU 81 starts the process of the flowchart in Fig. 16.

[0107] First, the CPU 81 determines whether or not a document has been set on the document tray 21 based on a signal from the document presence / absence sensor S31 (S501). If no document is present on the document tray 21 (S501: No), the CPU 81 does not proceed to the next process and waits until a document is placed on the document tray 21.

[0108] When it is determined that originals are loaded on the original tray 21 (S501: Yes), the CPU 81 determines whether or not a user has instructed to start feeding (S502). When a user has not instructed to start feeding (S502: No), the CPU 81 does not proceed to the next process and waits until a user instructs to start feeding. When it is determined that a user has instructed to start feeding (S502: Yes), the CPU 81 starts feeding the originals (S503). When feeding of the originals starts, the CPU 81 starts a jump-up detection process (S504). The jump-up detection process will be described later.

[0109] The CPU 81 determines whether or not a jump-up of the document has been detected in the jump-up detection process (S506). If a jump-up of the document has been detected (S506: Yes), the CPU 81 stops the transport of the document and displays a predetermined screen (FIGS. 18A and 18B) on the display panel 506a of the operation unit 506 (S507, S508). At this time, the CPU 81 switches between the first screen display (S507, FIG. 18A) and the second screen display (S508, FIG. 18B) depending on the detection result of the jump-up detection process. The first screen display and the second screen display will be described in detail later.

[0110] The first screen display and the second screen display (S507, S508) may be displayed simultaneously with the stop of document transport based on the detection of a document jumping up, or may be displayed after the document transport is stopped. For example, a screen showing the jam clearance method may be displayed on the display panel 506a immediately after the document transport is stopped, and the first screen display or the second screen display may be performed after the jam is cleared. In this case, after displaying the jam clearance screen, the CPU 81 displays the first screen or the second screen when it detects that the jammed document has been removed based on a signal from the sensor that detected the jam, or when the user inputs completion of jam clearance via the display panel 506a.

[0111] Thereafter, the CPU 81 determines the result of the user's selection on the screen display of the operation unit 506 (S509), and branches the subsequent processing.

[0112] If the user selects the "Continue job without resetting" button B1 (FIG. 18B), the CPU 81 resumes document transport in response to the button B1 being pressed (S510), without waiting for the user to reset the document. In this case, document transport resumes from the position at which document transport was stopped when the document jumping up was detected. The CPU also waits without raising the pickup roller 22 or lowering the document tray 21, and starts the feed motor 84 and transport motor 85 in response to the button B1 being pressed, thereby restarting document transport.

[0113] Note that when the transport of the original is resumed by pressing the "Continue job without resetting" button B1, the jump-up detection function may be disabled while the original is being transported. In other words, even if the jump-up detection sensor S20 is again in a detection state after the original transport is resumed (S510), the CPU 81 determines that the transport of the original can be continued. However, for the original following the original whose transport is resumed by pressing the button B1, the jump-up detection process (S504) may be executed, and if a jump-up is detected, the transport of the original may be stopped and a screen display (S507, S508) may be executed on the operation unit 506.

[0114] If the user selects the "Reload and continue job" button B2 (FIGS. 18A and 18B), the CPU 81 waits for the user to reload the document, and resumes document transport if the user instructs the job to resume after the reload (S502: Yes). In this case, the document is removed from the position at which the document transport stopped when the document jump was detected, and the document set in the predetermined position (reference position) on the document tray 21 is fed. To facilitate document reloading, the CPU 81 preferably moves the pickup roller 22 upward from the top document on the document tray 21 while waiting for the user to reload the document. If the document tray 21 (or a portion thereof) is movable up and down, the CPU 81 preferably lowers the document tray 21 while waiting for the user to reload the document.

[0115] If the user selects the "Turn off bounce detection and continue job" button B3 (FIGS. 18A and 18B), the CPU 81 disables the bounce detection function (S511) and waits for the user to reset the document. Then, if the user instructs the user to resume the job after the document is reset (S502: Yes), the CPU 81 resumes document transport. Because the bounce detection function is disabled after the job is restarted, the CPU 81 determines that document transport can continue regardless of the detection / non-detection state of the bounce detection sensor S20. In other words, even if the bounce detection sensor S20 changes from a non-detection state to a detection state after the user starts transporting the document, the CPU 81 determines that document transport can continue.

[0116] However, when the resumed job is completed, the disablement of the jump-up detection function is released. Therefore, in the next job that is started after the resumed job is completed, the jump-up detection process (S504) is executed, and if a jump-up is detected, the document transport is stopped and a screen display is executed on the operation unit 506 (S507, S508).

[0117] Furthermore, in the case of "turn off bounce detection and continue job," the document set in a predetermined position (reference position) on document tray 21 is fed, as in the case of "reset and continue job." To facilitate document resetting, it is preferable that CPU 81 moves pickup roller 22 upward from the top document on document tray 21 while waiting for the user to reset the document. Furthermore, if document tray 21 (or a part thereof) can be raised and lowered, it is preferable that CPU 81 lowers document tray 21 while waiting for the user to reset the document.

[0118] If the user selects the "Cancel Job" button B4 (FIGS. 18A and 18B), the CPU 81 ends the image reading job. In this case, the setting information input by the user when inputting the image reading job (for example, the reading conditions that can be set by operating button 601 on the setting screen in FIG. 4) is cleared, and the user must input the setting information again when inputting a new image formation job. Note that if any of the above-mentioned buttons B1 to B3 is selected, the setting information input by the user when inputting the image reading job is maintained.

[0119] On the other hand, if no jumping of the document is detected in the jumping detection process (S505: No), the CPU 81 determines that the document transport can be continued (S513). In this case, the CPU 81 controls the drive of the feed motor 84 and the transport motor 85 in accordance with a predetermined transport schedule to continue the document transport. Note that even if it is determined in S513 that the document transport can be continued, the CPU 81 may stop the document transport if an abnormality in the document transport is detected.

[0120] Thereafter, the CPU 81 determines whether the document being transported is the last document based on a signal from the document presence / absence sensor S31 (S514). If the document being transported is the last document (S514: Yes), the CPU 81 stops the feed motor 84 and the transport motor 85 to stop transport of the document (S515). If the document being transported is not the last document (S514: No), the CPU 81 returns to S503 and starts feeding the next document. The CPU 81 repeats the above process, and when transport of the last document is completed, the process of the flowchart ends.

[0121] [Jump-up Detection Process] The jump-up detection process in this embodiment will now be described. FIG. 17 is a flowchart showing the processing of the jump-up detection process executed by the CPU 81. When the jump-up detection process starts, the CPU 81 determines whether the jump-up detection sensor S20 is in a detection state (S601). If the jump-up detection sensor S20 is in a non-detection state (S601: No), the CPU 81 determines whether the document has been transported a predetermined distance since the start of document feeding (S603). If the document has not been transported a predetermined distance since the start of document feeding (S603: No), the process returns to S601. That is, the CPU 81 monitors whether the jump-up detection sensor S20 is in a detection state between the start of document feeding and the time the document has been transported the predetermined distance.

[0122] As in the first embodiment, the value of the predetermined distance is set to, for example, a value equal to or less than half the length of the document in the sheet transport direction (sheet feed direction). The value of the predetermined distance can be changed depending on the length of the document set in the document tray 21.

[0123] If the jump-up detection sensor S20 enters a detection state before the document has been conveyed a predetermined distance from the start of feeding (S601: Yes), the CPU 81 determines that the document is a bound document and that a jump-up has occurred. In this case, the CPU 81 sets the result of the jump-up detection process to "jump-up of bound document has occurred" (S602). The result of the jump-up detection process is recorded in the memory unit 507, for example, and is referenced in the document conveyance operation flow (FIG. 16).

[0124] On the other hand, if the document has been transported a predetermined distance from the start of feeding while the jump-up detection sensor S20 remains in a non-detecting state (S603: Yes), the CPU 81 continues to detect the document jump using the jump-up detection sensor S20. That is, the CPU 81 monitors the signal from the jump-up detection sensor S20 and waits until the trailing edge of the document passes the second skew detection sensor S12, which also serves as a post-separation sensor (S604, S606). That is, in this embodiment, the jump-up detection function is not disabled even after the document has been transported a predetermined distance from the start of feeding while the jump-up detection sensor S20 remains in a non-detecting state.

[0125] If the jump-up detection sensor S20 enters a detection state after the document has been transported a predetermined distance from the start of feeding and before the trailing edge of the document passes the second skew detection sensor S12 (S604: Yes), the CPU 81 determines that the document is a folded document and that the jump-up has occurred. In this case, the CPU 81 sets the result of the jump-up detection process to "jump-up of folded document occurred" (S606). The result of the jump-up detection process is recorded in the memory unit 507, for example, and is referenced in the document transport operation flow (FIG. 16).

[0126] On the other hand, if the trailing edge of the document passes the second skew detection sensor S12 without the jump-up detection sensor S20 changing from the non-detection state to the detection state (S606: Yes), the CPU 81 determines that the document has not jumped up. In this case, the CPU 81 sets the result of the jump-up detection process to "no jump-up" (S605) and records this result in the storage unit 507.

[0127] If the result of the jump-up detection process is "jump-up of bound document has occurred," the CPU 81 stops the document transport and displays the first screen (S507) as in the flow of the document transport operation described above (FIG. 16). If the result of the jump-up detection process is "jump-up of folded document has occurred," the CPU 81 stops the document transport and displays the second screen (S508) as in the flow of the document transport operation described above (FIG. 16). On the other hand, if the result of the jump-up detection process is "no jump-up," the CPU 81 determines that the document transport can continue as in the flow of the document transport operation described above (FIG. 16) (S505: No, S513).

[0128] In this embodiment, if the jump-up detection sensor S20 enters a detection state before the document has been transported a predetermined distance from the start of document feeding, the CPU 81 stops the transport of the document, regardless of the length of time that the jump-up detection sensor S20 has been in a detection state. Also, in this embodiment, if the jump-up detection sensor S20 enters a detection state before the document has been transported a predetermined distance from the start of document feeding, the CPU 81 stops the transport of the document, regardless of the number of times that the jump-up detection sensor S20 has entered a detection state.

[0129] 18A and 18B, examples of screen displays on the operation unit 506 will be described. Fig. 18A is an example of a first screen display that is displayed when "the occurrence of a bound document jumping up" is detected by the jumping-up detection process. Fig. 18B is an example of a second screen display that is displayed when "the occurrence of a folded document jumping up" is detected by the jumping-up detection process.

[0130] 18A, when "jumping up of bound document" is detected, a message M0 informing the user of a document transport abnormality, a message M3 urging the user to reset the document, and a message M4 regarding disabling the jumping up detection function are displayed. In this case, a button B2 for "Reset and continue job," a button B3 for "Turn off jumping up detection and continue job," and a button B4 for "Cancel job" are also displayed. The operations of the ADF 20 and the image reading device 10 when buttons B2 to B4 are selected are as described using FIG. 16.

[0131] 18A includes information prompting the user to reset the bound document and information prompting the user to remove staples from the document when resetting the bound document. However, message M3 may not include information prompting the user to reset the bound document, but may simply prompt the user to remove staples when resetting the bound document (for example, "Please remove staples when resetting stapled documents"). Furthermore, the information prompting the user to reset the bound document and the information prompting the user to remove staples from the document may each be displayed as separate messages or images.

[0132] On the other hand, as shown in FIG. 18B , if a "jump-up of a folded document" is detected, a message M0 informing the user of a document transport abnormality and a message M1 informing the user that the job can be continued without resetting the document are displayed. In this case, a message M2 urging the user to reduce the amount of document jump-up when resetting the folded document, a message M3 urging the user to reset the document, and a message M4 regarding disabling the jump-up detection function are displayed. In this case, a button B1 for "Continue job without resetting," a button B2 for "Reset and continue job," a button B3 for "Turn off jump-up detection and continue job," and a button B4 for "Cancel job" are displayed. The operation of the ADF 20 and the image reading device 10 when buttons B1 to B4 are selected is as described above with reference to FIG. 16 .

[0133] 18B includes information urging the user to reload the folded document and information urging the user to straighten the folds of the document (to reduce the amount of document jumping up) when reloading the folded document. However, message M2 may not include information urging the user to reload the folded document, but may simply prompt the user to reduce the amount of document jumping up when reloading the folded document (for example, "When reloading a document with creases, please straighten the creases."). Furthermore, the information urging the user to reload the folded document and the information urging the user to straighten the creases of the document may each be displayed as separate messages or images.

[0134] [Summary of this embodiment] According to this embodiment, when a jumping-up of an original is detected, the content of the screen display displayed on the display panel 506a of the operation unit 506 changes depending on whether the jumping-up is detected before the original has been transported a predetermined distance from the start of original feeding. If a jumping-up is detected after the original has been transported a predetermined distance from the start of original feeding (S604: Yes), a message M2 including information urging the user to smooth out creases in the original when resetting the original is displayed on the second screen (S508). On the other hand, if a jumping-up is detected before the original has been transported a predetermined distance from the start of original feeding (S601: Yes), such a message M2 is not displayed on the first screen (S507).

[0135] That is, if the detection means detects a jumping up of the sheet before the sheet has been conveyed a predetermined distance since the feeding means started to feed the sheet, the control means does not cause the display means to display a message urging the user to reduce the amount of jumping up of the sheet when resetting the sheet in the stacking section.Furthermore, if the detection means detects a jumping up of the sheet after the sheet has been conveyed a predetermined distance since the feeding means started to feed the sheet, the control means causes the display means to display the message.

[0136] As a result, if a document is detected as being folded and a document is being readjusted, the user who sees message M2 can avoid the document being readjusted again after the job is resumed by straightening out the folded document and then resetting it on document tray 21. Furthermore, if a document is detected as being readjusted for reasons other than the document being readjusted, message M2 is not displayed, thereby avoiding the inconvenience of confusing the user by providing unnecessary information.

[0137] Therefore, according to the present embodiment, it is possible to provide a sheet conveying device, an image reading device, and an image forming device that are capable of executing more appropriate control depending on the state of the sheet.

[0138] Furthermore, according to this embodiment, if a jump is detected before the document has been transported a predetermined distance from the start of document feeding (S601: Yes), a message M3 including information urging the user to remove the staples from the bound document is displayed on the first screen display (S507). In other words, assume that the detection unit detects a jump of the sheet before the sheet has been transported a predetermined distance from the start of sheet feeding by the feeding unit. In this case, the control unit uses the above-mentioned message M2 as the first message and, if there is a bound sheet stack, displays a second message (M3) urging the user to release the bound sheet stack.

[0139] Therefore, when the document is a bound document and the document is detected as jumping up, the user who sees the message M3 can avoid the document from being detected as jumping up again after the job is restarted by removing the staples and then resetting the document on the document tray 21.

[0140] [Modification] In the third embodiment, a configuration has been described in which a button operation on the screen display (FIGS. 18A and 18B) when a document is detected allows a command to disable the document jump-up detection function for the job. This configuration is not limited to this, and the user may operate the operation unit 506 to switch between enabling and disabling the document jump-up detection function before starting a job. For example, a setting screen displayed by operating button 602 on the screen of FIG. 4 may display a checkbox for selecting whether or not to perform document jump-up detection using the document jump-up detection sensor S20. If the document jump-up detection function is disabled on the setting screen, the disabled state of the document jump-up detection function remains even after the job submitted after the function is disabled is completed.

[0141] Other Examples The elements described as the above-described examples and their modified examples may be combined and applied to a single device. For example, in the flow of the document transport operation described in the third embodiment, the skew detection process described in the second embodiment may be performed in parallel with the jump-up detection process.

[0142] Furthermore, the contents of the screen displays mainly described in the third embodiment can be changed depending on the specific configuration and specifications of the ADF 20 and the image reading device 10. For example, the first screen display (FIG. 18A) may be configured not to display any of the messages M0, M3, and M4 and / or any of the buttons B2, B3, and B4. The second screen display (FIG. 18B) may be configured not to display any of the messages M0 to M4 and / or any of the buttons B1 to B4. As an example, the first screen display and the second screen display may not display the message M4 and button B3 related to turning off the bounce-up detection.

[0143] In each of the above-described embodiments, the image reading device 10 is described as being attached to the main body of the image forming device (printer main body 70), but the present technology may also be applied to an image reading device that is independent of the main body of the image forming device.

[0144] The electrophotographic image forming unit PU described in each of the above-mentioned embodiments is merely one example of an image forming means, and the image forming device may be equipped with an image forming unit of another type (e.g., an inkjet type) as an image forming means.

[0145] The present disclosure can also be realized by a process in which a program that realizes one or more functions of the above-described embodiments is supplied to a system or device via a network or a storage medium, and one or more processors in a computer of the system or device read and execute the program. The present disclosure can also be realized by a circuit (e.g., an ASIC) that realizes one or more functions.

[0146] The present disclosure can be used in a sheet conveying device that conveys a sheet, an image reading device that reads image information from a sheet, and an image forming device that forms an image on a recording material.

[0147] The present invention is not limited to the above-described embodiments, and various modifications and variations can be made without departing from the spirit and scope of the present invention. Therefore, the following claims are appended to apprise the public of the scope of the present invention.

[0148] This application claims priority based on Japanese Patent Application No. 2024-149809, filed August 30, 2024, the entire contents of which are incorporated herein by reference.

[0149] 20...sheet conveying device (ADF) / 21...loading section (document tray) / 22, 23, 24...feeding means / 81...control means (CPU) / 506a...display means (display panel) / S20...detection means (jump-up detection sensor)

Claims

1. A sheet transport device comprising: a stacking section on which sheets are stacked; feeding means for separating and feeding the sheets stacked on the stacking section one by one; detection means for detecting any jumping up of the sheet fed by the feeding means; and control means for stopping the feeding of the sheet based on the detection of the jumping up of the sheet by the detection means before the sheet has been transported a predetermined distance from the start of feeding of the sheet by the feeding means, and for allowing the feeding of the sheet to continue regardless of the detection result of the detection means after the sheet has been transported the predetermined distance from the start of feeding of the sheet by the feeding means.

2. The sheet transport device according to claim 1, wherein if the detection means detects a jumping up of the sheet before the sheet has been transported the specified distance from the start of sheet feeding by the feeding means, the control means stops feeding of the sheet regardless of the length of time that the detection means detects the jumping up of the sheet.

3. A sheet transport device according to claim 1 or 2, wherein the control means stops the feeding of the sheet when the detection means detects a jumping up of the sheet before the sheet has been transported the predetermined distance from the start of feeding of the sheet by the feeding means, regardless of the number of times the detection means detects the sheet jumping up.

4. The sheet transport device according to any one of claims 1 to 3, wherein the control means changes the value of the predetermined distance in accordance with the length in the sheet feeding direction of the sheets stacked on the stacking section.

5. The sheet transport device according to claim 4, wherein the predetermined distance is equal to or less than half the length of the sheets stacked on the stacking section in the sheet feeding direction.

6. A sheet transport device according to any one of claims 1 to 5, wherein the control means stops detection by the detection means after the sheet has been transported the predetermined distance from the start of feeding of the sheet by the feeding means.

7. A sheet transport device according to any one of claims 1 to 6, wherein the control means allows the sheet to continue to be fed regardless of the detection result received from the detection means after the sheet has been transported the predetermined distance from the start of feeding of the sheet by the feeding means.

8. A sheet conveying device according to any one of claims 1 to 7, wherein the feeding means is arranged above the stacking section and has a pickup roller that picks up a sheet from the stacking section, and the detection means detects the sheet at a detection position above the stacking section and upstream of the pickup roller in the sheet feeding direction.

9. The sheet transport device according to claim 8, wherein the distance in the sheet feeding direction from the reference position of the leading edge of the sheet in the stacking section to the detection position is less than 210 mm.

10. A sheet transport device according to any one of claims 1 to 9, further comprising a skew detection means for detecting skew of the sheet, wherein the control means stops feeding of the sheet when the skew detection means detects skew of the sheet, regardless of whether the sheet has been transported the specified distance since the feeding means started feeding the sheet.

11. The sheet conveying device according to claim 10, wherein the skew detection means includes a first sensor that detects the sheet, and a second sensor that is arranged at a different position from the first sensor in the sheet width direction perpendicular to the sheet feeding direction and detects the sheet, and detects skew of the sheet based on the difference in detection timing of the leading edge of the sheet by the first sensor and the second sensor.

12. A sheet conveying device according to any one of claims 1 to 11, wherein when a plurality of sheets are continuously fed from the stacking section, the control means allows the sheet feeding to continue regardless of the detection result of the detection means from the time when the trailing edge of the sheet passes the detection position of the detection means until the leading edge of the subsequent sheet passes the detection position of the detection means.

13. A sheet transporting device according to any one of claims 1 to 12, wherein the control means, when transporting a sheet having a first length in the sheet feed direction, executes a first mode in which the control means stops sheet feeding based on the detection means detecting a jump of the sheet before the sheet has been transported the predetermined distance from the start of feeding of the sheet by the feeding means, and allows sheet feeding to continue regardless of the detection result of the detection means after the sheet has been transported the predetermined distance from the start of feeding of the sheet by the feeding means, and when transporting a sheet having a second length in the sheet feed direction that is shorter than the first length, executes a second mode in which the control means allows sheet feeding to continue regardless of the detection result of the detection means before the sheet has been transported the predetermined distance from the start of feeding of the sheet by the feeding means and after the sheet has been transported the predetermined distance.

14. A sheet transport device comprising: a stacking section on which sheets are stacked; feeding means for separating and feeding the sheets stacked on the stacking section one by one; detection means for detecting any jumping up of the sheets fed by the feeding means; display means for displaying information; and control means for, if the detection means detects any jumping up of the sheets before the sheets have been transported a predetermined distance from the start of feeding of the sheets by the feeding means, not causing the display means to display a message urging the user to reduce the amount of jumping up of the sheets when resetting the sheets on the stacking section, and, if the detection means detects any jumping up of the sheets after the sheets have been transported the predetermined distance from the start of feeding of the sheets by the feeding means, causing the display means to display the message.

15. A sheet conveying device as described in claim 14, wherein the message is a first message, and when the detection means detects a sheet bouncing up before the sheet is conveyed the predetermined distance from the start of sheet feeding by the feeding means, the control means causes the display means to display a second message, if there is a bound sheet stack, that prompts the user to unbind the bound sheet stack.

16. The sheet transport device according to claim 14 or 15, wherein the control means changes the value of the predetermined distance in accordance with the length in the sheet feeding direction of the sheets stacked on the stacking section.

17. A sheet conveying device as claimed in any one of claims 1 to 16, wherein the detection means has a light-emitting unit that emits light and a light-receiving unit that emits a signal according to the light that enters from the light-emitting unit via an optical path that passes above the stacking unit, and detects the jumping up of a sheet when the optical path is blocked.

18. A sheet conveying device as described in any one of claims 1 to 17, wherein the feeding means has a pickup roller disposed above the stacking section that picks up a sheet from the stacking section, and the control means causes the feeding means to start feeding the sheet by rotating the pickup roller while it is in contact with the upper surface of the sheet on the stacking section.

19. An image reading device comprising: a sheet conveying device according to any one of claims 1 to 18; and reading means for reading image information from a sheet conveyed by said sheet conveying device.

20. An image forming apparatus comprising: the image reading device according to claim 19; and image forming means for forming an image on a recording material based on image information read by said image reading device.

Images