Sheet transport device, image reading device, and image forming device

Abstract

This provides users with more appropriate information when a seat bounces up. [Solution] A sheet transport device comprising: a loading section on which sheets are loaded; a feeding means for separating and feeding the sheets loaded in the loading section one by one; a detection means for detecting when a sheet is lifted up by the feeding means; a display means for displaying information; and a control means that, when the detection means detects when a sheet is lifted up after the start of a job to feed sheets from the loading section, stops the feeding of sheets by the feeding means and displays a message on the display means prompting the user to reduce the amount of sheet lifting when resetting the sheets in the loading section.

Description

Technical Field

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

Background Art

[0002] In Patent Document 1, it is described that based on the time and the number of times that a detection unit disposed above a document placement surface detects the lifting of the document, it is determined whether the document is a folded document folded in a Z shape or a bound document bundle.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When conveying a sheet with a crease, the conveyance of the sheet may be stopped based on the detection means detecting the bounce of the sheet. In such a case, if the user cannot understand the cause of the conveyance stop and resets the sheet, the conveyance stop based on the detection of the bounce may be repeated.

[0005] Therefore, an object of the present invention is to provide a sheet conveying device, an image reading device, and an image forming device that can provide more appropriate information to the user when the bounce of the sheet is detected.

Means for Solving the Problems

[0006] One aspect of the present invention is a sheet conveying device comprising: a loading section on which sheets are stacked; a feeding means for separating and feeding the sheets stacked in the loading section one by one; a detection means for detecting when a sheet is lifted up by the feeding means; a display means for displaying information; and a control means that, when the detection means detects that a sheet is lifted up after the start of a job to feed sheets from the loading section, stops the feeding of sheets by the feeding means and displays a message on the display means prompting the user to reduce the amount of sheet lifting when resetting the sheets in the loading section. [Effects of the Invention]

[0007] According to the present invention, more appropriate information can be provided to the user when a seat bounces up. [Brief explanation of the drawing]

[0008] [Figure 1] A schematic diagram of the printer. [Figure 2] Perspective view of the image reading device. [Figure 3] Control block diagram. [Figure 4] An example of the display panel settings screen. [Figure 5] A top view showing the location of the oblique detection sensor. [Figure 6] A perspective view showing the location of the bounce detection sensor. [Figure 7] Diagrams (a-c) illustrating the behavior of bound documents. [Figure 8] Diagrams (a, b) illustrating the behavior of unbound manuscripts. [Figure 9] Diagrams (a-c) illustrating the behavior of bound documents. [Figure 10] An explanatory diagram showing the behavior of a folded document. [Figure 11] A flowchart of the document transport operation according to the first embodiment. [Figure 12] A flowchart of the bounce detection process according to the first embodiment. [Figure 13]Example of screen display according to the first embodiment. [Figure 14] Flowchart of the document conveyance operation according to the second embodiment. [Figure 15] Example of screen display according to the second embodiment. [Figure 16] Flowchart of the document conveyance operation according to the third embodiment. [Figure 17] Examples of screen display according to the third embodiment (a, b). [Figure 18] Explanatory diagrams showing the behavior of the bound document (a, b). [Figure 19] Flowchart of the document conveyance operation according to the fourth embodiment. [Figure 20] Flowchart of the skew detection process according to the fourth embodiment. [Figure 21] Examples of screen display according to the fourth embodiment (a, b).

Mode for Carrying Out the Invention

[0009] Hereinafter, embodiments according to the present disclosure will be described with reference to the drawings. <L

[0010] 《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 the present embodiment. The printer 100 is a laser beam printer using an electrophotographic method. The printer 100 includes a printer main body <L [Figure 14] and an image reading apparatus 10 mounted on the upper part of the printer main body <L [Figure 14] . Further, the printer 100 includes an operation unit 506 that receives operations from a user. The operation unit 506 is provided with a display panel 506a as a display unit for displaying information to the user. The display panel 506a is a touch panel that can be touched and operated by the user with a finger. That is, the display panel 506a also functions as an input unit for receiving inputs from the user. The operation unit 506 may include hard keys such as a numeric keypad and an execution button as an input unit.

[0011] In the following, the side of the printer 100 where the operating unit 506 is located will be referred to as the front side, and the opposite side as the back side. That is, Figure 1 is a view of the printer 100 from the front side. In this embodiment, the term "sheet" includes not only plain paper but also special papers such as coated paper, recording materials of special shapes such as envelopes and index paper, and plastic films and cloths for overhead projectors, and the original document is also an example of a sheet.

[0012] The printer body 70 has an image forming engine 60 as an image forming means. The image forming engine 60 comprises an electrophotographic image forming unit PU and a fixing device 7. When a command is given to start the image forming operation, the photosensitive drum 1, which is a photoreceptor, rotates, and the drum surface is uniformly charged by the charging device 2. Then, the exposure device 3 modulates and outputs laser light based on image data transmitted from the 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) by toner supplied from the developing device 4 to become a toner image.

[0013] In parallel with this image forming operation, a feeding operation is performed to feed the sheet S, which is loaded in the cassette 9 or an unillustrated manual feed tray, 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 to the sheet S by the transfer roller 5. Toner remaining on the photosensitive drum 1 after the toner image transfer is collected by the cleaning device 6. The sheet S on which the unfixed toner image has been transferred is passed to the fixing device 7, where it is held between a pair of rollers and heated and pressurized. The sheet S on which the toner has been fixed is discharged to the discharge tray 71.

[0014] [Image reading device] Next, the image reading device 10 will be described. Figure 2 is a perspective view of the image reading device 10. As shown in Figures 1 and 2, the image reading device 10 includes an ADF 20 (Auto Document Feeder) as a sheet transport device for transporting the original document D, and a reading unit 40 as a reading means for reading image information from the original document transported by the ADF 20. The ADF 20 is rotatably supported relative to the reading unit 40 by a hinge (not shown) so that the document glass 41 can be opened. The original document D, which is an example of a sheet, may be blank paper, or an image may be formed on one or both sides.

[0015] The ADF20 includes a document tray 21 as a loading section on which documents D are stacked, and an output tray 32 on which 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 documents D set in the document tray 21. The first regulating plate 21a is positioned on the front side and abuts against the front end of the documents D stacked in the document tray 21. The second regulating plate is positioned on the back side and abuts against the back end of the documents D stacked in 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. Then, the position of the original document D is restricted by the first regulating plate 21a and the second regulating plate 21b contacting the edges of the original document D in the width direction.

[0016] The width direction refers to the direction perpendicular to the sheet transport direction in which the ADF 20 transports the document D (the sheet width direction). The width direction is the same direction as, for example, the rotation axis direction of the pickup roller 22 and the rotation axis direction of the feed roller 23. The sheet transport direction refers to the direction of movement of the document D along the transport path from the document tray 21, through the reading position Rd of the reading unit 40, to the output tray 32. In particular, the direction of movement of the sheet S when the document D is fed from the document tray 21 towards the main body of the ADF 20 is sometimes called the sheet feed direction.

[0017] The ADF20 includes a pickup roller 22, a feeding roller 23 and a separation roller 24, a transport roller pair 25, a lead roller pair 26, a lead roller pair 30, and a discharge roller pair 31. The feeding unit consisting of the pickup roller 22, the feeding roller 23, and the separation roller 24 constitutes the feeding means in this embodiment. Note that this feeding unit is just one example of a feeding means, and for example, a rotatably mounted belt-shaped transport member may be used instead of the pickup roller 22 and the feeding roller 23. Also, the separation roller 24 is just one example of a separation member, and a pad-shaped separation member (separation pad) having a friction member may be used.

[0018] Furthermore, the ADF20 includes a document presence 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 a detection means (skew detection means) for detecting 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.

[0019] Furthermore, the ADF20 has a bounce detection sensor S20 as a detection means (bounce detection means) for detecting when a document bounces up. Document bounce refers to the change in the vertical position of the document D at the detection position of the bounce detection sensor S20 to an upward position beyond a predetermined position when the document D is fed. As will be described later, document bounce occurs when the document D is a stack of documents bound with staples (bound documents) or when the document D has creases from being folded. In addition, document bounce can occur not only when the document D is deformed during feeding, but also when the document D is deformed in such a way that a part of the document D floats upward when it is set in the document tray 21.

[0020] The bounce 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 is incident via an optical path that passes over the document tray 21 (stacking unit). The bounce detection sensor S20 detects the bounce of the document D when the optical path is obstructed. In this embodiment, the detection position of the bounce detection sensor S20 is the position in the optical path from the light-emitting unit S21 to the light-receiving unit S22. In other words, the bounce detection sensor S20 is configured such that the signal from the light-receiving unit S22 changes depending on whether or not the document D has bounced, and the CPU 81 (Figure 3) can determine whether the document D has bounced based on the signal received from the light-receiving unit S22. In this embodiment, the predetermined position can be said to be the height of the optical path from the light-emitting unit S21 to the light-receiving unit S22.

[0021] The reading unit 40 includes a scanning glass 28, a jump platform 29, a reference whiteboard 42, a document glass 41, a first mirror base 43, a second mirror base 44, a lens 45, and a CCD line sensor 46. Inside the first mirror base 43 are a lamp 47 and a mirror 48. Inside the second mirror base 44 are mirrors 49 and 50. The first mirror base 43 and the second mirror base 44 are configured to be movable in the sub-scanning direction (left-right direction in the figure) by wires and drive motors (not shown).

[0022] The image reading device 10 can perform two modes: a scrolling mode in which the image of a document D loaded in the document tray 21 is read while being fed by the ADF 20, and a fixed mode in which the image of a document placed on the document glass 41 is read. The scrolling mode is selected when the document presence sensor S31 detects a document D loaded in the document tray 21, or when the scrolling mode is explicitly instructed by the operation unit 506.

[0023] When the skimming mode is activated, a pickup roller 22, supported by an arm (not shown), descends and contacts the uppermost document D on the document tray 21, and rotates. The document D is then fed by the pickup roller 22 and separated one sheet at a time at the separation nip formed by the feed roller 23 and the separation roller 24. The feed roller 23 is made of a rubber material or the like with less friction than the separation roller 24. A torque limiter is placed in the drive transmission path to the separation roller 24, so that the separation roller 24 rotates with the feed roller 23 when only one document is fed, but does not rotate when two or more documents are fed. In this way, the documents can be separated one sheet at a time by the feed roller 23 and the separation roller 24.

[0024] The document D, fed from the document tray 21, is transported by a pair of transport rollers 25 and then transported towards the scanning glass 28 by a pair of lead rollers 26. A platen guide roller 27 is positioned opposite the scanning glass 28. The platen guide roller 27 guides the document D so that it does not lift off the scanning glass 28 as it passes through it.

[0025] Then, as the document D passes through the reading position Rd opposite the reading glass 28, the image on the surface of the document D is read by the reading unit 40 via the reading glass 28. Specifically, light from the lamp 47 is shone on the document D as it is being transported, and the reflected light from the document D is guided to the lens 45 by mirrors 48, 49, and 50. The light that has passed through the lens 45 is then imaged into the light-receiving part of the CCD line sensor 46, converted into photoelectricity, and the image information is transmitted to the CPU 81. The reference whiteboard 42 serves as the reference for the reading brightness of the document D. After passing through the reading glass 28, the document D is guided to the lead roller pair 30 by the jump ramp 29 and discharged to the discharge tray 32 by the discharge roller pair 31.

[0026] On the other hand, the fixed reading mode is selected when the reading unit 40 detects a document D placed on the document 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 document glass 41, and the document D is scanned by the light emitted by the lamp 47. The image information converted photoelectrically by the light-receiving element of the CCD line sensor 46 is transferred to the CPU 81.

[0027] In this 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 consists of a lens array (1:1 optical system) arranged in the main scanning direction, CMOS image sensors arranged in the main scanning direction so as to face the original document D via the lens array, and a light source that illuminates the original document D with light. Alternatively, a CCD type or CIS type reading mechanism may be arranged inside the ADF 20. When reading mechanisms are arranged 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 document D in a single pass.

[0028] [Control Block] Figure 3 is a control block diagram relating to the CPU 81 as a control means. 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 (bounce detection sensor S20), and a document presence / absence sensor S31. The CPU 81 is also connected to a feed motor 84, a transport motor 85, and a lifting motor 86 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 lead roller pair 26, the lead roller pair 30, and the discharge roller pair 31. The lifting motor 86 is an example of a lifting means for raising and lowering the document tray 21. The CPU 81 is also connected to an operation unit 506 and a storage unit 507. The user can start the image reading operation (image reading job) and perform various settings by operating the control unit 506.

[0029] 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 next sheet after the preceding sheet based on the detection of the trailing edge of the preceding sheet by the second skew detection sensor S12. 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 lowering the cost of the product. However, a post-separation sensor may be placed separately from the skew detection unit S10. Also, the skew detection unit S10 may be placed downstream in the sheet transport direction from the post-separation sensor, which is located downstream and near the separation nip.

[0030] The CPU 81 controls the operation of the ADF 20 or the image reading device 10, as described below, by reading and executing a program stored in the memory unit 507. The CPU 81 is located, for example, on a control board mounted inside the housing of the reading unit 40 and is communicated with the control unit of the printer body 70. The CPU 81 may also be located in the ADF 20. Furthermore, some or all of the processing performed by the CPU 81, as described below, may be executed by the control unit of the printer body 70.

[0031] [Reading mode settings] Figure 4 shows one of the screens displayed on the display panel 506a of the operation unit 506, which is an example of a screen for the user to set the execution conditions for the image reading operation by the image reading device 10.

[0032] The screen shown in Figure 4 displays a start button 600 for instructing the start of the image reading operation, several buttons 601 for setting various conditions during image reading, and a button 602 for setting the bound document detection settings. Here, "bound document" refers to a stack of documents (sheets) consisting of multiple stapled documents D.

[0033] When the user presses the Start Read button 600, the image reader 10 starts an image reading operation (image reading job) which includes a series of operations including document transport to read image information from the document. If the screen shown in Figure 4 is displayed when setting up a copy job to duplicate the image of document D, pressing the Start Read button 600 (Copy Start button) will execute the image reading operation in the image reader 10 and the image forming operation in the printer body 70.

[0034] [Skew detection sensor] Next, the first skew detection sensor S11 and the second skew detection sensor S12 will be described. Figure 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 positioned downstream of the feed roller 23 in the sheet transport direction (sheet feeding direction). The first skew detection sensor S11 and the second skew detection sensor S12 are positioned side by side in the width direction. That is, the first skew detection sensor S11 and the second skew detection sensor S12 are positioned at the same position in the sheet transport direction. Although there are two skew detection sensors in this embodiment, the number of skew detection sensors may be three or more.

[0035] 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. In addition, if the degree of skew of the document is large, the CPU 81 may determine that the document is stapled (that the document is a bound document).

[0036] The CPU 81 determines that the document is skewed if, within a predetermined time elapsed since one of the first skew detection sensors S11 or the second skew detection sensor S12 detected the document, the other sensor does not detect 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 the document if there is a large difference in the detection timing between the first skew detection sensor S11 and the second skew detection sensor S12. The processing of the skew detection process executed by the CPU 81 will be described later.

[0037] [Jump detection sensor] Next, the bounce detection sensor S20 will be described. As shown in Figure 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 document in the document tray 21. The first wall portion 33 and the second wall portion 34 are a pair of walls that are positioned opposite each other, with the support surface of the document tray 21 in between. The first wall portion 33 is positioned in front of the first regulating plate 21a, and the second wall portion 34 is positioned behind the second regulating plate 21b. The light-emitting unit S21 is positioned in the first wall portion 33, and the light-receiving unit S22 is positioned in the second wall portion. That is, the light-emitting unit S21 and the light-receiving unit S22 are positioned with a gap in the width direction so as to sandwich the document setting area on the support surface 21s of the document tray 21. The document setting area is the area covered by the document when the largest possible document that can be set in the document tray 21 is set in terms of width.

[0038] Figure 6 is a perspective view showing the position of the bounce detection sensor S20. The position of the bounce 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 Figure 6, the bounce detection sensor S20 is positioned above the support surface 21s of the document tray 21 (loading unit) in the vertical direction. The bounce detection sensor S20 is also positioned 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 bounce detection sensor S20 is set upstream of the pickup roller 22 in the sheet feed direction.

[0039] Furthermore, 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 is less than 210 mm in the sheet feeding direction. In other words, the distance from the reference position of the leading edge of the document (sheet) in the document tray 21 (stacking section) to the detection position in the sheet feeding direction is less than 210 mm. The reference position is downstream of the pickup roller 22 and upstream of the separation nip in the sheet feeding direction, and is, for example, the position where the leading edge of the document D abuts against a shutter member that can be retracted during feeding. With this configuration, even when an A3-sized Z-fold document is set in the document tray 21 in the long-edge feeding direction, the bounce of the bound document can be appropriately detected. However, the position (detection position) of the bounce detection sensor S20 can be changed according to the document size (especially the maximum size) that the document tray 21 supports. In addition, to enable support for a wider variety of sheet sizes, multiple bounce detection sensors may be placed at different positions in the sheet feeding direction.

[0040] The CPU 81 can determine whether or not the document D is bouncing up based on the signal from the light-receiving unit S22. If the light path from the light-emitting unit S21 to the light-receiving unit S22 is blocked by the document, the CPU 81 may, for example, determine that the document is a bound document and stop feeding it.

[0041] [Method for detecting bouncing] Next, before explaining the bounce detection process, we will explain the movement of the document when a bounce occurs. In the following explanation, the state in which the light receiving unit S22 receives light from the light emitting unit S21 of the bounce detection sensor S20 is referred to as the "non-detection state" or "transmission state" of the bounce detection sensor S20. The state in which the light receiving unit S22 does not receive light from the light emitting unit S21 is referred to as the "detection state" or "light-blocking state" of the bounce detection sensor S20. The detection state is the state in which the bounce detection sensor S20 has detected the document bouncing up, and the non-detection state is the state in which the bounce detection sensor S20 has not detected the document bouncing up.

[0042] Figures 7(a) to 7(c) are perspective views showing the movement of a document when a stapled document Dst is fed. Figure 7(a) shows the state when the stapled document Dst is loaded, Figure 7(b) shows the state when the stapled document Dst has been fed to the feed roller 23, and Figure 7(c) shows the state when the stapled document Dst has been lifted up. Note that the stapled document Dst is a stack of documents in which the first document Dst1 and the second document Dst2 are stapled together by staples ST. Figures 8(a) and 8(b) are perspective views showing the movement of an unstapled document D when it is fed. Figure 8(a) shows the state when the document D is being transported, and Figure 8(b) shows the state when the trailing edge of the transported document D has passed the second skew detection sensor S12.

[0043] As shown in Figure 7(a), when feeding begins with the bound document Dst loaded in the document tray 21, the bound document Dst is transported by the pickup roller 22 to the separation nip formed by the feed roller 23 and the separation roller 24. As shown in Figure 7(b), when the bound document Dst reaches the separation nip, it is transported in such a way that the first document Dst1 and the second document Dst2 are separated. At this time, the first document Dst1 moves 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 the separation roller 24 and remains in the document tray 21. However, since the first document Dst1 and the second document Dst2 are bound together by staples ST, the force received from each roller may cause the first document Dst1 to curl up and spring upwards.

[0044] As shown in Figure 7(c), when the first document Dst1 bounces up, the first document Dst1 blocks the light path from the light-emitting unit S21 to the light-receiving unit S22, preventing light from the light-emitting unit S21 from reaching the light-receiving unit S22. In other words, the bounce detection sensor S20 switches from a non-detection state to a detection state. When the bounce detection sensor S20 is in a detection state, the CPU 81 can determine that the document has bounced up.

[0045] On the other hand, when an unstapled document D is transported as shown in Figure 8(a), the bounce detection sensor S20 remains in a non-detection state. Then, as shown in Figure 8(b), the trailing edge of the document D passes through the second skew detection sensor S12, which also serves as a separation sensor, while the bounce detection sensor S20 remains in a non-detection state. If the document D passes through the second skew detection sensor S12 without any bounce detection, the CPU 81 can determine that the next document D is ready to be fed (allow the start of feeding).

[0046] Figures 9(a) to 9(c) are perspective views showing the movement of a bound document Dst when it is fed with its trailing end stapled. Figure 9(a) shows the bound document Dst in a loaded state, Figure 9(b) shows the bound document Dst fed to the feed roller 23, and Figure 9(c) shows the bound document Dst bouncing up. While Figures 7(a) to 7(c) illustrate the case where the leading end of the bound document Dst is stapled, Figures 9(a) to 7(c) explain the case where the trailing end of the bound document Dst is stapled. The leading end of the document or bound document is the downstream end of the document or bound document in the sheet transport direction, and the trailing end of the document or bound document is the upstream end of the document or bound document in the sheet transport direction.

[0047] As shown in Figure 9(a), when a bound document Dst with its rear end stapled is fed, the document is transported to the feed roller 23 without bouncing up, as shown in Figure 9(b). However, while the first document Dst1 moves in the sheet transport direction and passes through the separation nip, the second document Dst2 is prevented from passing through the separation nip by the separation roller 24 and remains in the document tray 21. As a result, the stapled rear end of the bound document Dst bounces up. This blocks the light path from the light-emitting unit S21 to the light-receiving unit S22, causing the bounce detection sensor S20 to detect the bounce. In this way, the CPU 81 can detect the bounce of the document even if the position of the staple ST is different.

[0048] [Detection of document bouncing due to folding] The above explains how the upward movement of a stapled, bound document Dst can be detected during transport. However, if document D is a folded document, upward movement may be detected even if it is a single, unstapled sheet. A folded document (folded sheet) is a document (sheet) that has creases from being folded, such as a Z-fold (single-sleeve fold) and therefore cannot be completely flattened when placed on a flat surface such as a desk.

[0049] Figure 10 shows an example of a folded document, specifically a folded document Df that has been Z-folded along two folds, a valley fold Dv and a mountain fold Dp, and is placed in the document tray 21 with the mountain fold Dp facing the rear end. As shown in Figure 10, the folded document Df may be placed with the fold crease remaining, such that the mountain fold Dp protrudes upward from the portion closer to the front of the valley fold Dv.

[0050] When using a folded document Df, if the folded document Df is set in the document tray 21 in a flat state so that the height of the mountain fold portion Dp is sufficiently low, the image reader 10 can transport the folded document Df normally. However, if a folded document Df that is not sufficiently flat is set, the bounce detection sensor S20 will detect the document bouncing up when the protruding part of the folded document Df passes the bounce detection sensor S20 after feeding has started. Specifically, in the case of a Z-folded folded document Df shown in Figure 10, the part between the valley fold portion Dv and the mountain fold portion Dp of the folded document Df obstructs the light path from the light-emitting unit S21 to the light-receiving unit S22, causing the bounce detection sensor S20 to change from a non-detection state to a detection state.

[0051] Although Figure 10 shows a Z-folded document Df, the document may also bounce up if it is folded in a way other than Z-folding, such as a bi-fold (center fold) or tri-fold. In other words, regardless of the folding method, if a folded document is placed in the document tray 21 with a part of the document protruding upwards due to the fold, the bounce-up detection sensor S20 will detect the document bouncing up after the feeding of the folded document begins.

[0052] [Jump detection process] The bounce detection process will now be explained. Figure 12 is a flowchart showing the process of the bounce detection process executed by the CPU 81. When the bounce detection process starts, the CPU 81 determines whether the bounce detection sensor S20 is in a detection state (S201). If the bounce detection sensor S20 is not in a detection state (S201: No), the CPU 81 determines whether the second skew detection sensor S12, which also serves as a post-separation sensor, has changed from ON to OFF, that is, whether the trailing edge of the document has passed through the separation nip or not (S202). If the trailing edge of the document has not passed through the separation nip (S202: No), the process returns to S201. In other words, the CPU 81 monitors whether the bounce detection sensor S20 is in a detection state from the start of document feeding until the trailing edge of the document leaves the separation nip.

[0053] The start of document feeding refers to the point at which the pickup roller 22 comes into contact with the document to be fed (the topmost document on the document tray 21) and is rotated (S103 in Figure 11). In other words, the start of document feeding is the point at which the rotational drive of the pickup roller 22 by the feeding motor 84 begins after the stationary pickup roller 22 has come into contact with the document, or the point at which the rotating pickup roller 22 descends and comes into contact with the document. The CPU 81 can also determine 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 the pickup roller 22.

[0054] If the bounce detection sensor S20 detects a bounce before the trailing edge of the document passes through the separation nip (S201: Yes), the CPU 81 determines that a bounce has occurred in the document and sets the result of the bounce detection process to "Bounce Occurred" (S203). In other words, the detection means of this embodiment detects a bounce in the sheet when the optical path from the light-emitting unit S21 to the light-receiving unit S22 is obstructed during the period from the start of sheet feeding until the downstream detection means (second oblique detection sensor) downstream of the separation nip detects the passage of the trailing edge of the sheet. On the other hand, if the trailing edge of the document passes through the separation nip while the bounce detection sensor S20 remains in a non-detection state (S202: Yes), the CPU 81 determines that a bounce has not occurred in the document and sets the result of the bounce detection process to "No Bounce" (S204). The result of the bounce detection process is recorded, for example, in the storage unit 507 and referenced in the document transport operation flow (Figure 11).

[0055] [Document transport operation flow] Next, the control of document transport by the ADF20 will be explained using a flowchart. Figure 11 is a flowchart showing the process of document transport operation performed by the CPU81. When power is turned on to the printer 100, the CPU81 starts the process shown in the flowchart of Figure 11. Note that the flowchart in Figure 11 describes the operation when no skew is detected in the document as a result of skew detection by the first skew detection sensor S11 and the second skew detection sensor S12.

[0056] First, the CPU 81 determines whether or not a document has been placed in the document tray 21 based on the signal from the document presence sensor S31 (S101). If there is no document in the document tray 21 (S101: No), the CPU 81 does not proceed to the next step and waits until a document is loaded into the document tray 21.

[0057] If the CPU determines that a document is loaded in the document tray 21 (S101: Yes), it determines whether the user has instructed the start of document feeding (S102). The CPU determines that the start of document feeding has been instructed, for example, when the user presses the start scan button 600 on the screen shown in Figure 4. If the start of document feeding has not been instructed (S102: No), the CPU does not proceed to the next step and waits until the start of document feeding is instructed.

[0058] If feeding is instructed to begin (S102: Yes), the CPU 81 begins feeding the documents (S103). Specifically, the CPU 81 starts driving the feeding unit (22, 23, 24) with the feeding motor 84 and lowers the pickup roller 22 to contact the topmost document. Also, if the document tray 21 (or part thereof) can be raised and lowered, the CPU 81 raises the document tray 21 before lowering the pickup roller 22. Once document feeding begins, the CPU 81 starts the bounce detection process (S104). The contents of the bounce detection process are as described above.

[0059] The CPU 81 determines whether or not a document has bounced up during the bounce detection process (S105). If a document bounce is detected (S105: Yes), the CPU 81 stops the feed motor 84 and the transport motor 85 to stop transporting the document (S106). In addition, if a document bounce is detected, the CPU 81 displays a predetermined screen using the display panel 506a (S107). This screen display (Figure 13) includes a message prompting the user to reduce the amount of document bounce by straightening out creases in folded documents when resetting the document in the document tray 21. Details of the screen display in S107 will be described later.

[0060] The S107 screen display may be shown simultaneously with the cessation of document transport based on the detection of a document bouncing up, or it may be shown after the cessation of document transport. For example, immediately after the cessation of document transport, a screen showing the jam handling method may be displayed on the display panel 506a, and the S107 screen display may be shown after the jam handling is completed. In this case, the CPU 81 will display the S107 screen after the jam handling screen is displayed, if it detects the removal of the jammed document based on a signal from the sensor that detected the jam, or if the user inputs the completion of the jam handling via the display panel 506a.

[0061] Subsequently, CPU 81 determines the user's selection result for the screen display in S107 (S108) and branches the subsequent processing accordingly.

[0062] If the user selects button B2 (Figure 13) for "Reset and continue job", the CPU 81 waits for the user to reset the document and resumes document transport when the user instructs to resume the job (S102: Yes). In this case, the document is removed from the position where document transport stopped due to detection of the document bouncing up, and the document set in the predetermined position (reference position) on the document tray 21 is fed. Furthermore, to facilitate the resetting of the document, it is preferable for the CPU 81 to move the pickup roller 22 upward away from the topmost document on the document tray 21 while waiting for the user to reset the document. Also, if the document tray 21 (or a part thereof) can be raised and lowered, it is preferable for the CPU 81 to lower the document tray 21 while waiting for the user to reset the document.

[0063] If the user selects button B3 (Figure 13) for "Turn off bounce detection and continue job", the CPU 81 disables the bounce detection function (S109) and waits for the user to reset the document. Then, after the document is reset, the CPU 81 resumes document transport if the user instructs to resume the job (S102: Yes). Since the bounce detection function is disabled after the job has resumed, the CPU 81 determines that it is possible to continue transporting the document regardless of whether the bounce detection sensor S20 is detecting or not. In other words, even if the bounce detection sensor S20 changes from a non-detection state to a detection state after the transport of the document reset by the user has started, the CPU 81 determines that it is possible to continue transporting the document. Note that disabling the bounce detection function may also be done by disabling the bounce detection sensor S20 itself (stopping power supply to the light-emitting unit S21 and the light-receiving unit S22, and not accepting signals from the light-receiving unit S22).

[0064] However, once the resumed job finishes, the bounce detection function is deactivated. Therefore, in the next job started after the resumed job finishes, the bounce detection process (S104) is executed, and if a bounce is detected, the document transport is stopped and the screen display on the operation unit 506 is activated (S106, S107).

[0065] Furthermore, in the case of "turn off jump detection and continue job," the document set in the predetermined position (reference position) on the document tray 21 is fed, similar to the case of "reset and continue job." In addition, to facilitate the resetting of the document, it is preferable for the CPU 81 to move the pickup roller 22 upward away from the top document on the document tray 21 while waiting for the user to reset the document. Also, if the document tray 21 (or a part thereof) can be raised and lowered, it is preferable for the CPU 81 to lower the document tray 21 while waiting for the user to reset the document.

[0066] If the user selects button B4 (Figure 13) for "Cancel Job," the CPU 81 terminates the image reading job. In this case, the settings information entered by the user when inputting the image reading job (for example, the execution conditions that can be set by operating button 601 on the settings screen in Figure 4) is cleared (S114), and the user must re-enter the settings information when inputting a new image forming job. Alternatively, the CPU 81 may automatically use settings information such as the document size acquired using the sensor on the document tray 21, or it may use a value that has been pre-set as the initial value of the execution conditions. Note that if buttons B1 to B3 are selected, the settings information entered by the user when inputting the image reading job is maintained, and the document transport operation is performed based on the same execution conditions as before the job was interrupted, even after the job is resumed.

[0067] On the other hand, if no document bounce is detected during the bounce detection process (S105: No), the CPU 81 determines that document transport can be continued (S111). 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 and continues transporting the document. Even if the CPU 81 determines in S111 that document transport can be continued, if a document transport abnormality is detected, the CPU 81 may stop transporting the document. A transport abnormality refers to, for example, a delay or stagnation of the document on the transport path in the ADF 20 (collectively called a jam). The CPU 81 controls document transport while monitoring for jams and other transport abnormalities based on the detection results of each sensor placed on the transport path of the document (for example, the second skew detection sensor S12 as a post-separation sensor).

[0068] Subsequently, the CPU 81 determines whether the document being transported is the final document based on the signal from the document presence sensor S31 (S112). If the document being transported is the final document (S112: Yes), the CPU 81 stops the feed motor 84 and the transport motor 85, and stops the transport of the document (S113). If the document being transported is not the final document (S112: No), the CPU 81 returns to S103 and starts feeding the next document. The CPU 81 repeats the above process, and once the transport of the final document is complete, it clears the job settings information (S114) and terminates the job.

[0069] [Screen display] By the way, as mentioned above, when transporting a folded sheet (folded document), the bounce detection sensor S20 detects when the document bounces up. In a configuration where sheet transport is stopped based on the detection of a document bouncing up, usability may be reduced. That is, even though a bounce is detected because the document is folded, if the user does not understand the reason for the transport stop and resets the sheet, the transport stop based on the detection of a bounce may be repeated.

[0070] Therefore, in this embodiment, the aim is to provide the user with appropriate information through the display (UI display, screen display) on the display panel 506a (display means).

[0071] Figure 13 illustrates an example of the screen display on the display panel 506a. Figure 13 shows an example of the screen display that appears when the document bounces up, detected by the bounce-up detection process.

[0072] In the example display shown in Figure 13, the following messages are displayed: message M0 indicating an abnormality in document transport, messages M2a and M2b regarding resetting the document, and message M3 regarding disabling the bounce detection function. In this example display, buttons B2 for "Reset and continue job", B3 for "Turn off bounce detection and continue job", and B4 for "Cancel job". The operation of the ADF 20 and image reader 10 when buttons B2 to B4 are selected is as explained using the flowchart in Figure 11.

[0073] The message M2a in Figure 13 includes information prompting the user to re-insert the bound document and information prompting the user to remove the staples from the document when re-inserting it. However, the message M2a may not include information prompting the user to re-insert the bound document, but simply prompts the user to remove the staples when re-inserting the document (for example, "Please remove the staples when re-inserting a stapled document."). Furthermore, the information prompting the user to re-insert the bound document and the information prompting the user to remove the staples from the document may be displayed as separate messages or images.

[0074] The message M2b in Figure 13 includes information prompting the user to reset the folded document and information prompting the user to reduce the amount of bounce when resetting the folded document. However, the message M2b may not include information prompting the user to reset the folded document, but simply prompts the user to reduce the amount of bounce when resetting the folded document (for example, "When resetting a folded document, please straighten the creases."). Also, the information prompting the user to reset the folded document and the information prompting the user to reduce the amount of bounce may be displayed as separate messages or images.

[0075] [Summary of this embodiment] According to this embodiment, when the bounce detection sensor S20 detects a bounce during an image reading job, the CPU 81 stops the document transport (S106) and displays message M2b on the display panel 506a. Message M2b includes information encouraging the reduction of the amount of bounce when resetting a folded document. In other words, the control means of this embodiment stops the feeding of the sheet by the feeding means when the detection means detects a sheet bounce after the start of a job that feeds a sheet from the loading unit, and displays a message on the display means encouraging the reduction of the amount of bounce when resetting the sheet in the loading unit.

[0076] With this configuration, a user who sees message M2b can realize that the document has bounced up because it is folded, and can then straighten the folds to reduce the amount of bounce and re-set the document. Furthermore, it can prevent repeated transport stops based on bounce detection when a document is folded, thereby improving usability.

[0077] Therefore, according to this embodiment, it is possible to provide a sheet transport device, an image reading device, and an image forming device that can provide more appropriate information to the user when a sheet bounces up.

[0078] Furthermore, according to this embodiment, when the bounce detection sensor S20 detects a bounce during an image reading job, a message M2a regarding the resetting of bound documents is displayed on the display panel 506a along with message M2b. In other words, the first message is a message prompting the user to reduce the amount of bounce when resetting sheets in the loading section. In this case, if the detection means detects a bounce of a sheet after the start of the job, the control means of this embodiment displays a second message on the display means along with the first message, prompting the user to release the bound state of the sheet bundle if there is a bound sheet bundle.

[0079] With this configuration, a user who sees message M2a can realize that the document has bounced up because it is a bound document, and can then reset the document after removing the staples or otherwise correcting the binding. In other words, it is possible to provide the user with more appropriate information so that they can take the appropriate action depending on whether the cause of the bounce is a folded document or a bound document.

[0080] Furthermore, according to this embodiment, when the bounce detection sensor S20 detects a bounce during an image reading job, a button B2 labeled "Reset and continue job" is displayed on the display panel 506a. In other words, the control means of this embodiment displays a first button on the display means instructing the user to reset the sheet in the loading section and continue the job if the detection means detects that the sheet has bounced up after the job has started. This allows the user to choose to continue the job by resetting the document after resolving the cause of the bounce.

[0081] Furthermore, according to this embodiment, when the bounce detection sensor S20 detects a bounce during an image reading job, a button B3 labeled "Turn off bounce detection and continue job" is displayed on the display panel 506a. In other words, the control means of this embodiment displays a button on the display means instructing the user to continue the job without performing bounce detection by the detection means when the detection means detects a bounce of the sheet after the job has started. This allows the user to choose to continue the job regardless of the result of the bounce detection. For example, it may be preferable to disable the bounce detection function if the user is aware that a bounce of the document was falsely detected due to a malfunction of the bounce detection sensor S20.

[0082] Furthermore, according to this embodiment, both the button B2 (first button) for "Reset and continue job" and the button B3 (second button) for "Turn off bounce detection and continue job" are displayed, allowing the user to select the appropriate option according to the condition of the document, etc.

[0083] If button B2 (the first button) is operated (S108:B2), and the document feeding is resumed based on the job restart instruction (S102:Yes), if the document bounce detection sensor S20 detects a bounce, the document transport is stopped again (S106). On the other hand, if button B3 (the second button) is operated (S108:B3), even if the document feeding is resumed based on the job restart instruction (S102:Yes) and the document bounce detection sensor S20 detects a bounce, the document transport continues (S109, S111). Therefore, the ADF20 can perform appropriate operations according to the user's wishes.

[0084] Furthermore, according to this embodiment, when the bounce detection sensor S20 detects a bounce in an image reading job, the "Cancel Job" button B4 is displayed on the display panel 506a. In other words, the control means of this embodiment displays a button on the display means to instruct the user to cancel the job when the detection means detects a bounce of the sheet after the job has started. This allows the user to choose to cancel the job, for example, if the user knows that they cannot resolve the cause of the detected bounce of the document.

[0085] Furthermore, according to this embodiment, both the "Reset and continue job" button B2 (first button) and the "Cancel job" button B4 (third button) are displayed, allowing the user to select the appropriate option according to the status of the document, etc.

[0086] When button B2 (the first button) is pressed (S108:B2), the job is restarted using the execution conditions set on the settings screen (Figure 4) at the start of the job. On the other hand, when button B4 (the third button) is pressed (S108:B4), the set execution conditions are cleared, and a new job is executed using the newly set execution conditions on the settings screen (Figure 4) after the job has been canceled. Therefore, if the user wishes to reset the conditions, the job can be quickly restarted using the previously set execution conditions, and if the user wishes to cancel the job, a new job can be executed with the new execution conditions.

[0087] 《Second Embodiment》 An image forming apparatus according to the second embodiment will now be described. In this embodiment, the display content on the display panel 506a when a document bounce is detected differs from that of the first embodiment. Hereinafter, elements denoted by reference numerals common to the first embodiment have basically the same configuration and operation as those described in the first embodiment unless otherwise specified, and the parts that differ from the first embodiment will be mainly described.

[0088] [Document transport operation flow] Figure 14 is a flowchart showing the processing of the document transport operation in this embodiment. The flowchart in Figure 14 describes the operation when no skew is detected in the document as a result of skew detection by the first skew detection sensor S11 and the second skew detection sensor S12. The processing of S301 to S306, S309, and S311 to S314 is the same as S101 to S106, S109, and S111 to S114 in the first embodiment (Figure 11), respectively, so the explanation is omitted.

[0089] If the CPU 81 detects that the document has bounced up during the bounce detection process (S305: Yes), it stops transporting the document (S306) and displays a predetermined screen on the display panel 506a (S307). This screen display (Figure 16) includes a message M1 and a button B1 regarding continuing the job without resetting the document in the document tray 21. Details of the screen display in S307 will be described later. Note that the screen display in S307 may be displayed simultaneously with the stop of document transport based on the detection of the document bouncing up, or it may be displayed after the stop of document transport.

[0090] Subsequently, the CPU 81 determines the user's selection result for the screen display in S307 (S308) and branches the subsequent processing. The processing when buttons B2, B3, and B4 are selected is the same as in the first embodiment, so the explanation is omitted.

[0091] If the user selects button B1 (Figure 16) for "Continue job without resetting," the CPU 81 resumes document transport based on the press of button B1 without waiting for the user to reset the document (S310). In this case, the CPU 81 determines that document transport can be continued (S311). Document transport resumes from the position where it stopped due to the detection of the document bouncing up. The CPU 81 also waits without raising the pickup roller 22 or lowering the document tray 21, and based on the press of button B1, starts the feed motor 84 and transport motor 85 to resume document transport. The processing after the resumption of transport merges with S311.

[0092] Furthermore, if document transport is resumed by pressing the "Continue job without resetting" button B1, the bounce detection function may be disabled while the document is being transported. In other words, even if the bounce detection sensor S20 detects a bounce again after the document transport is resumed (S310), the CPU 81 will determine that it is possible to continue transporting the document. However, for the document following the one transported by button B1, the bounce detection process (S304) may be executed, and if a bounce is detected, the document transport may be stopped and the screen display on the operation unit 506 (S307) may be displayed.

[0093] [Screen display] Using Figure 16, the screen display shown on the display panel 506a when a document bounce is detected by the bounce detection process in this embodiment will be explained.

[0094] In this example, the following messages are displayed: message M0 indicating an abnormality in document transport, message M1 regarding continuing the job without resetting the document, messages M2a and M2b regarding resetting the document, and message M3 regarding disabling the bounce detection function. In this example, buttons B1 for "Continue job without resetting," B2 for "Reset and continue job," B3 for "Continue job with bounce detection turned off," and B4 for "Cancel job." The operation of the ADF 20 and image reader 10 when button B1 is selected is as described above. The operation of the ADF 20 and image reader 10 when buttons B2 to B4 are selected is as described in the first embodiment (Figure 11).

[0095] [Summary of this embodiment] Similar to the first embodiment, if a document bounce is detected, the CPU 81 stops transporting the document (S306), and displays a message M2b on the display panel 506a prompting the user to reduce the amount of document bounce when resetting a folded document (S307). Therefore, according to this embodiment, it is possible to provide a sheet transport device, an image reading device, and an image forming device that can provide more appropriate information to the user when a sheet bounce is detected.

[0096] Furthermore, according to this embodiment, when the sheet bounce detection sensor S20 detects a bounce during an image reading job, a button B1 labeled "Continue job without resetting" is displayed on the display panel 506a. In other words, the control means of this embodiment displays a button on the display means instructing the user to continue the job without resetting the sheet in the loading unit when the detection means detects that the sheet has bounced up after the job has started. This allows the user to quickly resume the job without resetting the document.

[0097] Furthermore, according to this embodiment, both the "Reset and continue job" button B2 (first button) and the "Continue job without resetting" button B1 (fourth button) are displayed, allowing the user to select the appropriate option depending on the condition of the document. For example, if the user understands that there is a low risk of a transport malfunction, such as when only one folded document is set, the user will select button B1.

[0098] When button B2 (the first button) is pressed (S308:B2), the CPU 81 lowers the document tray 21 (the stacking section) without resuming document feeding and waits for a reset, then raises the document tray 21 based on the instruction to start feeding (S302:Yes). On the other hand, when button B1 (the fourth button) is pressed (S308:B1), the CPU 81 resumes transporting documents without lowering the document tray 21 (the stacking section) (S310). Therefore, if the user wishes to reset the documents, the document tray 21 is lowered to facilitate the user's reset, and if the user decides that a reset is unnecessary, the document tray 21 is not lowered and transport can be quickly resumed.

[0099] 《Third Embodiment》 An image forming apparatus according to the third embodiment will now be described. This embodiment differs from the second embodiment in that the display content on the display panel 506a switches according to the stopping position of the document when a document bounce is detected. Hereinafter, elements denoted by reference numerals common to the first and second embodiments have basically the same configuration and operation as those described in the first and second embodiments unless otherwise specified, and the parts that differ from the first and second embodiments will be mainly described.

[0100] [Document transport operation flow] Figure 16 is a flowchart showing the processing of the document transport operation in this embodiment. The flowchart in Figure 16 describes the operation when no skew is detected in the document as a result of skew detection by the first skew detection sensor S11 and the second skew detection sensor S12. The processing of S401 to S406 and S410 to S416 is the same as S301 to S306 and S308 to S314 in the second embodiment (Figure 14), respectively, so the explanation is omitted.

[0101] If the CPU 81 detects that the document has bounced up during the bounce detection process (S405: Yes), it stops the document transport (S406) and displays a predetermined screen on the display panel 506a (S408, S409). At that time, it determines the position of the document at the moment the document transport stops due to the bounce detection (S407) and switches between displaying the first screen display (S408, Figure 17(a)) or the second screen display (S409, Figure 17(b)). Details of the first and second screen displays will be described later.

[0102] The CPU 81 determines the position of the document when document transport stops, based on the time when the document bounce is detected, the time when the leading edge of the document is detected by a sensor on the transport path of the ADF 20 immediately before the bounce is detected, and the document transport speed. In this embodiment, if the leading edge of the document has not yet passed the reading position Rd (Figure 1) of the reading unit 40 when document transport stops (S407: Yes), the CPU 81 displays the first screen (S408). On the other hand, if the leading edge of the document has already passed the reading position Rd when document transport stops (S407: No), the CPU 81 displays the second screen (S409). The processing when the user selects buttons B1 to B4 for the first screen display or the second screen display may be the same as the processing described in the second embodiment (Figure 14).

[0103] The first and second screen displays (S408, S409) may be displayed simultaneously with the stopping of document transport (S406), or they may be displayed after the stopping of document transport. Also, if the leading edge of the document has already passed the reading position Rd of the reading unit 40 at the time the document transport stops (S407: No), the image information partially read by the reading unit 40 is discarded. In other words, the storage area for storing read image data that was allocated to the document in which the bounce was detected is released in the storage unit 507, and new read image data can be written.

[0104] [Screen display] Using Figures 17(a) and 17(b), the screen display shown on the display panel 506a when a document bounce is detected in this embodiment will be explained.

[0105] Figure 17(a) shows an example of the screen display when document transport is stopped before the leading edge of the document passes the reading position Rd. In this case, the screen display may be the same as the screen display when a document bounce is detected in the second embodiment (Figure 15). In other words, the screen display when document transport is stopped before the leading edge of the document passes the reading position Rd includes a message M1 and a button B1 regarding continuing the job without resetting the document.

[0106] Figure 17(b) shows an example of the screen display when document transport is stopped after the leading edge of the document has passed the reading position Rd. In this case, the screen display may be the same as the screen display when a document bounce is detected in the first embodiment (Figure 13). In other words, the screen display when document transport is stopped before the leading edge of the document has passed the reading position Rd does not include the message M1 and button B1 regarding continuing the job without resetting the document.

[0107] [Summary of this embodiment] Similar to the first embodiment, if a document bounce is detected, the CPU 81 stops transporting the document (S406), and when resetting a folded document, it displays a message M2b on the display panel 506a prompting the user to reduce the amount of document bounce (S408, S409). Therefore, according to this embodiment, it is possible to provide a sheet transport device, an image reading device, and an image forming device that can provide more appropriate information to the user when a sheet bounce is detected.

[0108] Furthermore, according to this embodiment, if the document transport is stopped before the leading edge of the document passes the reading position Rd, the "Continue job without resetting" button B1 is displayed on the display panel 506a (S408, Figure 17(a)). On the other hand, if the document transport is stopped before the leading edge of the document passes the reading position Rd, the "Continue job without resetting" button B1 is not displayed on the display panel 506a (S409, Figure 17(b)). In other words, the control means displays the fourth button on the display means if the detection means detects that the sheet has bounced up before the leading edge of the sheet reaches the reading position where image information is read from the sheet. Also, the control means does not display the fourth button on the display means if the detection means detects that the sheet has bounced up after the leading edge of the sheet has reached the reading position.

[0109] As described in the second embodiment, if only one folded document is set, for example, even if the bounce detection sensor S20 detects that the document has bounced, it may be possible to continue transporting the document without any problems. However, if the leading edge of the document has already reached the reading position Rd, it may not be possible to correctly read the image information even if document transport is resumed. For example, immediately after resuming transport, the document transport speed is not stable, so the magnification in the sub-scanning direction of the read image information may change within a single image. Also, for example, in a configuration where the drive timing of the CCD line sensor 46 is synchronized based on the passing timing of a sensor placed near the reading position, it may not be possible to start reading after transport is resumed because synchronization cannot be achieved (or the timing is off).

[0110] According to this embodiment, if the document transport stops when the leading edge of the document has already reached the reading position Rd, the option to continue the job without resetting the document is not displayed on the display panel 506a, thus avoiding the inconveniences described above. On the other hand, if the document transport stops before the leading edge of the document reaches the reading position Rd, the same advantages as in the second embodiment can be obtained by presenting the user with the option to continue the job without resetting the document.

[0111] 《Fourth Embodiment》 An image forming apparatus according to the fourth embodiment will be described. In this embodiment, an example of control that performs document skew detection in parallel with document bounce detection will be described. Hereinafter, elements denoted by reference numerals common to the first and second embodiments will have basically the same configuration and operation as those described in the first and second embodiments unless otherwise specified, and the parts that differ from the first and second embodiments will be mainly described.

[0112] [Method for detecting skew] First, before explaining the flowchart of the skew detection process, let's describe the movement of the document when skew occurs. Figures 18(a) and 18(b) are perspective views showing the movement of a bound document Dst when it is being fed. Figure 18(a) shows the bound document Dst in the loaded state, and Figure 18(b) shows the bound document Dst being fed and skew occurring.

[0113] As shown in Figure 18(a), when feeding begins with the bound document Dst loaded on the document tray 21, the bound document Dst is transported by the pickup roller 22 to the separation nip formed by the feed roller 23 and the separation roller 24. As shown in Figure 18(b), when the bound document Dst reaches the separation nip, it is transported in such a way that the first document Dst1 and the second document Dst2 are separated.

[0114] The first document, Dst1, moves 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 the separation roller 24 and remains in the document tray 21. However, since the first document Dst1 and the second document Dst2 are stapled together by a staple ST, the first document Dst1 may rotate around the staple ST. In this case, the side of document Dst1 that is stapled together by the staple ST is not transported, so the first skew detection sensor S11 turns OFF. On the other hand, the side of document Dst1 that is not stapled together by the staple ST is transported downstream, so the second skew detection sensor S12 turns ON.

[0115] In this way, the CPU 81 can determine the skewness of the document by the difference in the timing at which the two skew detection sensors turn ON. Here, we have explained the reason why skew occurs when the document is a bound document Dst, but skew can also occur in unbound documents due to various reasons such as misalignment of the setting position or wear of the rollers. The skew detection unit S10 can detect the skewness of a document regardless of whether the document is a bound document Dst or not.

[0116] [Skewing detection process] Next, the skew detection process (S505 in Figure 20) will be explained using a flowchart. Figure 19 is a flowchart showing the processing of the skew detection process executed by CPU 81.

[0117] First, the CPU 81 waits until either the first oblique detection sensor S11 or the second oblique detection sensor S12 turns ON (S601, S602).

[0118] If the second oblique detection sensor S12 turns ON first (S602: Yes), the CPU 81 measures the time difference until the first oblique detection sensor S11 turns ON (S603, S604). That is, if a predetermined time Tth [ms] has elapsed after the second oblique detection sensor S12 turns ON while the first oblique detection sensor S11 remains OFF (S604: Yes), the CPU 81 determines that oblique movement has occurred (S605) and terminates the oblique movement detection process. On the other hand, if the first oblique movement detection sensor S11 turns ON before the predetermined time Tth has elapsed after the second oblique movement detection sensor S12 turns ON (S603: Yes), the CPU 81 determines that oblique movement has not occurred (S609) and terminates the oblique movement detection process.

[0119] If the first oblique detection sensor S11 turns ON first (S601: Yes), the CPU 81 measures the time difference until the second oblique detection sensor S12 turns ON (S606, S607). That is, if a predetermined time Tth has elapsed after the first oblique detection sensor S11 turns ON while the second oblique detection sensor S12 remains OFF (S607: Yes), the CPU 81 determines that oblique movement has occurred (S605) and terminates the oblique movement detection process. On the other hand, if the second oblique movement detection sensor S12 turns ON before the predetermined time Tth has elapsed after the first oblique movement detection sensor S11 turns ON (S606: Yes), the CPU 81 determines that oblique movement has not occurred (S609) and terminates the oblique movement detection process.

[0120] Here, the predetermined time Tth is a value determined according to the document transport speed, etc., and is 30 ms as an example. However, the value of the predetermined time Tth is not limited to this. Also, the value of the predetermined time Tth may be different in S604 and S607.

[0121] Furthermore, in S605, the CPU 81 sets the result of the skew detection process to "skew present". Specifically, the CPU 81 records information in the storage unit 507 indicating that no skew occurred in the document. In S606, the CPU 81 sets the result of the skew detection process to "no skew". Specifically, the CPU 81 records information in the storage unit 507 indicating that no skew occurred in the document.

[0122] The CPU 81 waits until the second skew detection sensor S12 turns OFF before S609 (S608). If the second skew detection sensor S12 remains ON (S608: No) and the predetermined limit time elapses (i.e., if it fails to detect that the trailing edge of the document has passed the separation nip), the CPU 81 may determine that a jam has occurred.

[0123] Thus, the skew detection unit S10 of this embodiment detects the skewness 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).

[0124] [Document transport operation flow] Figure 19 is a flowchart showing the processing of the document transport operation in this embodiment. The processing of S501-S504 and S510-S516 is the same as S301-S304 and S308-S314 in the second embodiment (Figure 12), respectively, so their explanation is omitted.

[0125] After the CPU 81 starts feeding the document in S503, it simultaneously performs the bounce detection process (S504) and the skew detection process (S505) as explained using Figure 20. Subsequent processing branches based on the results of the bounce detection process and the skew detection process (S506).

[0126] If the document is detected to be bouncing up and also skewed, the CPU 81 stops the document transport (S507a) and displays screen A on the display panel 506a (S508). Even if the document is not detected to be bouncing up but is detected to be skewed, the CPU 81 stops the document transport (S507a) and displays screen A on the display panel 506a (S508). In other words, in this embodiment, the processing when skewed document is detected is the same regardless of whether or not the document is bouncing up. However, the message in screen display A may be changed depending on whether or not the document is bouncing up.

[0127] If the document is detected to be bouncing up but not skewed, the CPU 81 stops transporting the document (S507b) and displays screen B on the display panel 506a (S509). If neither the document is detected to be bouncing up nor skewed, the CPU 81 determines that it is possible to continue transporting the document (S513) and continues transporting the document.

[0128] [Screen display] Using Figures 21(a) and 21(b), the screen display shown on the display panel 506a when a document is detected to be flipped up or skewed will be explained in this embodiment.

[0129] Figure 21(a) shows an example of screen display A when skewed document is detected. Screen display A includes message M0 indicating an abnormality in document transport, message M2a and button B2 regarding resetting the document, message M3 and button B3 regarding disabling the bounce detection function, and button B4 instructing the job to be canceled. On the other hand, screen display A does not include messages or buttons regarding folded documents. For example, screen display A does not include message M2b (Figure 21(b)), which contains information prompting the user to reduce the amount of document bounce when resetting the document.

[0130] Figure 21(b) shows an example of screen display B when no skew of the document is detected, and only document bouncing is detected. Screen display B includes message M0 indicating a document transport abnormality, messages M2a, M2b and button B2 regarding resetting the document, message M3 and button B3 regarding disabling the bouncing detection function, and button B4 instructing to cancel the job. The message regarding resetting the document includes message M2b, which contains information encouraging the user to reduce the amount of document bouncing when resetting the document. Screen display B also includes message M1 and button B1 regarding continuing the job without resetting the document.

[0131] The operation when the user selects buttons B1 to B4 in response to screen display A or B may be the same as that described in the first to third embodiments. In this embodiment, if button B3 is pressed in response to screen display A or B, the jump detection function and the skew detection function may be disabled together. In other words, button B3 may be a button that disables all abnormal document detection functions at once. Message M3 may also indicate that all abnormal document detection functions have been disabled at once.

[0132] [Summary of this embodiment] Similar to the first embodiment, if a document bounce is detected, the CPU 81 stops transporting the document (S507a), and displays a message M2b on the display panel 506a prompting the user to reduce the amount of document bounce when resetting a folded document (S509). Therefore, according to this embodiment, it is possible to provide a sheet transport device, an image reading device, and an image forming device that can provide more appropriate information to the user when a sheet bounce is detected.

[0133] Furthermore, according to this embodiment, if the skew detection unit S10 detects skew in the document, message M2b is not displayed regardless of whether the bounce detection sensor S20 detects that the document has bounced up (S508, Figure 21(a)). On the other hand, if the skew detection unit S10 does not detect skew in the document and the bounce detection sensor S20 detects that the document has bounced up, message M2b is displayed (S509, Figure 21(b)). In other words, if the skew detection unit detects skew in the sheet after the start of the job, the control means does not display a message on the display means, regardless of whether the detection means detects that the sheet has bounced up. Also, if the skew detection unit does not detect skew in the sheet after the start of the job and the detection means detects that the sheet has bounced up, the control means displays a message on the display means. The message referred to here is message M2b, which contains information encouraging the user to reduce the amount of bounce in the document when resetting a folded document.

[0134] If skew is detected in the document, it is highly likely that the skew and / or upward curling is due to reasons other than a folded document. Therefore, by not displaying message M2b when skew is detected, it is possible to avoid user confusion and other inconveniences caused by presenting unnecessary information. On the other hand, if only upward curling is detected and no skew is detected, displaying message M2b will provide the user with more appropriate information, including how to deal with folded documents.

[0135] Other examples The elements described in each of the above embodiments and their modified forms may be combined and applied to a single device. For example, in the document transport operation flow described in the first to third embodiments, the skew detection process described in the fourth embodiment may be performed in parallel with the bounce detection process.

[0136] Furthermore, the content of the screen display described in each embodiment can be changed according to the specific configuration and specifications of the ADF 20 and the image reading device 10. For example, in the screen display exemplified in the second embodiment (Figure 15), the configuration may be such that none of the messages M0 to M3 and / or none of the buttons B1 to B4 are displayed. As an example, the message M3 and button B3 related to disabling bounce detection may not be displayed. Also, the wording of the messages and the layout of the buttons can be changed.

[0137] Alternatively, instead of displaying multiple messages and buttons on a single screen, messages may be displayed sequentially. For example, messages and buttons corresponding to the most likely cause of the detected flip-up or skew (e.g., bound document) may be displayed, and if the user indicates that the problem is not resolved, messages and buttons corresponding to the next cause (e.g., folded document) may be displayed.

[0138] Furthermore, content similar to the screen display described in each embodiment may be displayed on the display of an external computer (for example, a personal computer or smartphone) that is communicatively connected to the ADF 20 or image reading device 10.

[0139] In the embodiments described above, an image reading device 10 attached to the main body of the image forming apparatus (printer body 70) was described. However, this technology may also be applied to an image reading device that is independent of the main body of the image forming apparatus.

[0140] The electrophotographic image forming unit PU described in each of the embodiments above is merely one example of an image forming means, and the image forming apparatus may also include an image forming unit of another type (e.g., an inkjet type) as an image forming means.

[0141] (Other embodiments) The present invention can also be realized by supplying a program that implements one or more of the functions of the above-described embodiments to a system or device via a network or storage medium, and by having one or more processors in the computer of that system or device read and execute the program. It can also be realized by a circuit (e.g., an ASIC) that implements one or more functions. [Explanation of Symbols]

[0142] 20...Sheet transport 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 detection sensor)

Claims

1. The loading section where the sheets are loaded, A feeding means for separating and feeding the sheets loaded in the loading section one by one, A detection means for detecting the upward movement of the sheet being fed by the feeding means, A means for displaying information, A control means which, when the detection means detects that the sheet is bouncing up after the start of a job to feed the sheet from the loading unit, stops the feeding of the sheet by the feeding means and displays a message on the display means prompting the user to reduce the amount the sheet bounces up when resetting the sheet in the loading unit, A sheet conveying device characterized by comprising the following features.

2. The aforementioned message is considered the first message. If the detection means detects a sheet bouncing up after the start of the job, the control means causes the display means to display a second message, along with the first message, prompting the user to release the bound state of the sheet bundle if there is a bound sheet bundle. The sheet conveying device according to feature 1.

3. The control means, when the detection means detects that the sheet has bounced up after the start of the job, causes the display means to display a first button indicating that the sheet should be reset in the loading section and the job should be continued. The sheet conveying device according to feature 1.

4. The control means, when the detection means detects that the sheet has bounced up after the start of the job, displays a second button on the display means together with the first button, which instructs the detection means to continue the job without detecting the bounce up. The sheet conveying device according to feature 3.

5. If the detection means detects that the sheet has bounced up after the start of the job, and the first button is operated, the control means starts feeding the sheet by the feeding means based on the job restart instruction, and then stops feeding the sheet by the feeding means if the detection means detects that the sheet has bounced up again. If the second button is operated, the control means starts feeding the sheet by the feeding means based on the job restart instruction, and then continues transporting the sheet without stopping the feeding means if the detection means detects that the sheet has bounced up again. The sheet conveying device according to feature 4.

6. The control means, when the detection means detects that the sheet has bounced up after the start of the job, displays a third button on the display means, together with the first button, which instructs the cancellation of the job. The sheet conveying device according to feature 3.

7. The system further includes setting means for setting the execution conditions of the job, When the detection means detects that the sheet has bounced up after the start of the job, the control means restarts the job using the execution conditions at the start of the job when the first button is operated, and when the third button is operated, executes a new job using the execution conditions set by the setting means after the job has been canceled. The sheet conveying device according to feature 6.

8. The control means, when the detection means detects that the sheet has bounced up after the start of the job, causes the display means to display a fourth button, together with the first button, which instructs the user to continue the job without resetting the sheet in the loading section. The sheet conveying device according to feature 3.

9. The aforementioned loading section is further provided with a lifting mechanism for raising and lowering it. When the detection means detects that the sheet has bounced up after the start of the job, the control means lowers the loading section without resuming the feeding of the sheet by the feeding means when the first button is operated, and then raises the loading section based on the instruction to start feeding, and when the fourth button is operated, it resumes the feeding of the sheet by the feeding means without lowering the loading section. The sheet conveying device according to feature 8.

10. The control means, if the detection means detects that the sheet has bounced up before the leading edge of the sheet reaches the reading position where image information is read from the sheet, causes the fourth button to be displayed on the display means, and if the detection means detects that the sheet has bounced up after the leading edge of the sheet has reached the reading position, the fourth button is not displayed on the display means. The sheet conveying device according to feature 8.

11. The control means, when the detection means detects that the sheet has bounced up after the job has been restarted, causes the display means to display a button indicating that the job should continue without the detection means detecting the bounce. The sheet conveying device according to feature 1.

12. The control means, when the detection means detects that the sheet has bounced up after the start of the job, causes the display means to display a button that instructs the cancellation of the job. The sheet conveying device according to feature 1.

13. The control means, when the detection means detects that the sheet has bounced up after the start of the job, causes the display means to display a button indicating that the job should be continued without resetting the sheet in the loading section. The sheet conveying device according to feature 1.

14. The system further includes a skew detection means for detecting the skewness of the sheet, If the skew detection means detects skew in the sheet after the start of the job, the control means will not display the message on the display means, regardless of whether the detection means has detected the sheet bouncing up. If the skew detection means does not detect skew in the sheet after the start of the job, and the detection means has detected the sheet bouncing up, the control means will display the message on the display means. The sheet conveying device according to feature 1.

15. The skew detection means includes a first sensor for detecting a sheet and a second sensor for detecting a sheet, which is positioned at a different location from the first sensor in the sheet width direction perpendicular to the sheet feeding direction, and detects the skew of the sheet based on the difference in the timing of detection of the leading edge of the sheet by the first sensor and the second sensor. The sheet conveying device according to feature 14.

16. The detection means comprises a light-emitting unit that emits light, and a light-receiving unit that is positioned so that the light is incident on it via an optical path passing above the loading unit, and which emits a signal corresponding to the incident light. The sheet conveying device according to feature 1.

17. The feeding means has a separating nip to separate the sheets one by one. The system further includes a downstream detection means for detecting the passage of a sheet downstream of the separation nip in the sheet feeding direction, The detection means detects the sheet bouncing up if the optical path is obstructed during the period from the start of sheet feeding by the feeding means until the downstream detection means detects the passage of the rear end of the sheet. The sheet conveying device according to feature 16.

18. A sheet conveying device according to any one of claims 1 to 17, A reading means for reading image information from a sheet being transported by the aforementioned sheet transport device, An image reading device characterized by comprising the following:

19. The image reading device according to claim 18, An image forming means for forming an image on a recording material based on the image information read by the aforementioned image reading device, An image forming apparatus characterized by comprising:

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