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

Abstract

To provide a sheet conveying device, an image reading device, and an image forming apparatus that can detect bound documents even when documents with different widths are loaded in a mixed state.SOLUTION: An ADF 20 comprises: a first skew detection sensor S11 and a second skew detection sensor S12 detecting skew of a document D to be fed; and a light emitting unit S21 and a light receiving unit S22 detecting warpage of the document D to be fed. A CPU 81 stops the feeding when the skew of the document D is detected and when the warpage of the document is detected. When a different-width mixed loading mode is set in which a plurality of documents with different widths are loaded, the CPU 81 does not execute stoppage of feeding based on the detection of the skew, but executes stoppage of feeding based on the detection of the warpage.SELECTED DRAWING: Figure 6

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 a sheet, and an image forming apparatus that forms an image on a recording material. [Background technology]

[0002] Conventionally, image reading devices mounted on copying machines, facsimile machines, digital multifunction machines, etc. are known that read images of documents while transporting the documents using an ADF (Auto Document Feeder). Such an ADF separates and feeds a plurality of documents loaded on a document tray one by one. Therefore, the ADF cannot separate and feed stapled documents (so-called "bound documents"), and if a bound document is fed by mistake, the document may be damaged.

[0003] Patent Document 1 proposes a sheet conveying device that detects bound documents using a jump detection means that detects a jump of a document and a skew detection means that detects a skew of the document. By stopping the feeding of the document when a bound document is detected, it is possible to prevent the document from being damaged. The jump detection means is composed of a sensor provided above the document tray, and the skew detection means is composed of multiple sensors arranged side by side in the width direction. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-17298 Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, the document tray is provided with a pair of regulating plates that regulate the widthwise position of the document set. When multiple documents of different widths are set on the document tray (so-called "mixed widths"), the smaller document is set in a state where it is abutted against one of the regulating plates. This causes a problem that the position of the smaller document is shifted from the center of transport, and the skew detection unit erroneously detects the skew.

[0006] SUMMARY OF THE PRESENT DISCLOSURE In view of the above, an object of the present invention is to provide a sheet conveying device, an image reading device, and an image forming device that are capable of detecting bound documents even when documents of different widths are mixed and loaded. [Means for solving the problem]

[0007] One aspect of the present invention is a sheet conveying device comprising a loading section on which sheets are loaded, a feeding means for separating and feeding the sheets loaded on the loading section one by one, a first detection means for detecting skew of the sheet fed by the feeding means, a second detection means for detecting bouncing of the sheet fed by the feeding means, a control means for stopping feeding by the feeding means when skew of the sheet is detected by the first detection means and when bouncing of the sheet is detected by the second detection means, and a setting means for setting a different width mixed loading mode in which multiple sheets of different widths are loaded on the loading section, wherein when the different width mixed loading mode is set by the setting means, the control means does not stop feeding based on detection of skew by the first detection means, but stops feeding based on detection of bouncing by the second detection means.

[0008] Another aspect of the present invention is a sheet conveying device comprising: a loading section on which sheets are loaded; a feeding means for separating and feeding the sheets loaded on the loading section one by one; a first detection means for detecting skew of the sheet fed by the feeding means; a second detection means for detecting a jumping up of the sheet fed by the feeding means; a control means for determining that the sheets loaded on the loading section are a bound document when skew of the sheet is detected by the first detection means and when a jumping up of the sheet is detected by the second detection means; and a setting means for setting a different widths mixed loading mode in which multiple sheets of different widths are loaded on the loading section, wherein when the different widths mixed loading mode is set by the setting means, the control means does not determine whether the sheet is a bound document based on the detection of skew by the first detection means, but performs a determination whether the sheet is a bound document based on the detection of jumping up by the second detection means.

[0009] Another aspect of the present invention is a sheet conveying device comprising: a loading section on which sheets are loaded; a feeding means for separating and feeding the sheets loaded on the loading section one by one; a first detection means for detecting skew of the sheet fed by the feeding means; a second detection means for detecting bouncing of the sheet fed by the feeding means; a control means for stopping feeding by the feeding means when skew of the sheet is detected by the first detection means and when bouncing of the sheet is detected by the second detection means; and a setting means for setting a first setting of whether to enable or disable detection of skew of the sheet by the first detection means and a second setting of whether to enable or disable detection of bouncing of the sheet by the second detection means. Effect of the Invention

[0010] According to the present invention, it is possible to provide a sheet conveying device, an image reading device, and an image forming device that are capable of detecting bound documents even when documents of different widths are mixed and loaded. [Brief description of the drawings]

[0011] [Figure 1] FIG. [Diagram 2] FIG. [Diagram 3] 10A is an example of a screen for making copy settings, and FIG. 10B is an example of a screen for making loading mode settings. [Figure 4] FIG. [Diagram 5] FIG. 4 is a perspective view showing the position of a jump-up detection sensor. [Figure 6] 4 is a flowchart of an original feeding operation. [Figure 7] 13 is a flow chart of a bounce detection process. [Figure 8] 1A is a perspective view showing a state where bound documents are stacked, FIG. 1B is a perspective view showing a state where bound documents are fed, and FIG. 1C is a perspective view showing a state where bound documents jump up. [Figure 9] 1A is a perspective view showing a state in which a normal document is being conveyed, and FIG. 1B is a perspective view showing a state in which the conveyed normal document has passed a second skew detection sensor. [Figure 10] 1A is a perspective view showing a state where bound documents are stacked, FIG. 1B is a perspective view showing a state where bound documents are fed, and FIG. 1C is a perspective view showing a state where bound documents jump up. [Figure 11] 11 is a flowchart of a skew detection process. [Figure 12] 1A is a top view showing a state where bound documents are stacked, and FIG. 1B is a top view showing a state where bound documents are fed and skew occurs. [Figure 13] 1A is a top view showing a state in which mixed originals of different widths are stacked, and FIG. 1B is a top view showing a state in which mixed originals of different widths are fed. [Figure 14] 13 is an example of a screen for configuring bound document detection settings. [Figure 15] FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] <First embodiment> DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. Note that the following embodiment is an example of the present invention, and is not intended to limit the technical scope of the present invention.

[0013] [Image forming device] First, an image forming apparatus according to a first embodiment will be described. FIG. 1 is a schematic cross-sectional view of a printer 100 as an image forming apparatus according to this embodiment. The printer 100 is an electrophotographic laser beam printer. The printer 100 includes a printer body 70 and an image reading device 10 mounted on the upper part of the printer body 70. The printer 100 also 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 that displays information to the user. The display panel 506a is a touch panel that the user can operate by touching it with his / her finger.

[0014] In the following, the side of the printer 100 where the operation unit 506 is provided is called the front side, and the opposite side is called the back side. That is, Fig. 1 is a diagram of the printer 100 as seen from the front side. In addition, in this embodiment, the sheet includes, in addition to plain paper, special paper such as coated paper, recording materials having special shapes such as envelopes and index paper, plastic films and cloths for overhead projectors, and the original is also an example of a sheet.

[0015] The printer body 70 has an image forming engine 60. The image forming engine 60 includes an image forming unit PU as an electrophotographic image forming means, and a fixing device 7. When a command is issued to start an image forming operation, a photosensitive drum 1, which is a photoconductor, rotates, and the drum surface is uniformly charged by a charging device 2. Then, an exposure device 3 modulates and outputs a laser beam based on image data transmitted from an image reading device 10 or an external computer, and scans the surface of the photosensitive drum 1 to form an electrostatic latent image. This electrostatic latent image is visualized (developed) by toner supplied from a developing device 4 to become a toner image.

[0016] In parallel with this image forming operation, a feeding operation is performed to feed the recording material S loaded on the cassette 9 or a manual feed tray (not shown) toward the image forming engine 60. The fed recording material S is transported in accordance with the progress of the image forming operation by the image forming unit PU. Then, the toner image carried on the photosensitive drum 1 is transferred to the recording material S by the transfer roller 5. Toner remaining on the photosensitive drum 1 after the toner image transfer is collected by a cleaning device 6. The recording material S with the transferred unfixed toner image is delivered to a fixing device 7, where it is sandwiched between a pair of rollers and heated and pressurized. The recording material S with the fixed toner is discharged to a discharge tray 71.

[0017] [Image reader] Next, the image reading device 10 will be described. As shown in Fig. 1, the image reading device 10 includes an ADF 20 (Auto Document Feeder) as a sheet conveying device that conveys an original D, and a reading unit 40 as a reading means that reads the original conveyed by the ADF 20. The ADF 20 is rotatably supported with respect to the reading unit 40 by a hinge (not shown) so that an original table glass 41 can be opened. The original D, which is an example of a sheet, may be blank paper or may have an image formed on one or both sides.

[0018] The ADF 20 has a document tray 21 as a loading section on which the document D is loaded, and a discharge tray 32 to which the document D is discharged. The document tray 21 is provided with a first regulation plate 21a and a second regulation plate 21b as regulation means for regulating the widthwise position of the document D set in the document tray 21. The first regulation plate 21a is disposed on the front side and abuts against the front end of the document D loaded on the document tray 21. The second regulation plate is disposed on the rear side and abuts against the rear end of the document D loaded on the document tray 21. The pair of regulation plates, the first regulation plate 21a and the second regulation plate 21b, can move in the widthwise direction in conjunction with each other by an interlocking mechanism (not shown). Specifically, when one of the first regulation plate 21a and the second regulation plate 21b moves in the widthwise direction, the other of the first regulation plate 21a and the second regulation plate 21b moves in the opposite direction. The first and second regulating plates 21a and 21b come into contact with the widthwise ends of the document D, thereby regulating the position of the document D. Note that the widthwise direction is a direction perpendicular to the sheet transport direction (feed direction) in which the ADF 20 transports the document D.

[0019] The ADF 20 has a pickup roller 22, a feed roller 23, a separation roller 24, a pair of transport rollers 25, a pair of lead rollers 26, a pair of lead rollers 30, and a pair of discharge rollers 31. The pickup roller 22, the feed roller 23, and the separation roller 24 are an example of a feeding means in this embodiment. The ADF 20 also has a document presence / absence sensor S31 that detects the presence or absence of a document D on the document tray 21, and a first skew detection sensor S11 and a second skew detection sensor S12 as a first detection means that detects skew of the document D. The first skew detection sensor S11 is an example of a first sensor, and the second skew detection sensor S12 is an example of a second sensor. The ADF 20 also has a light emitting unit S21 and a light receiving unit S22 as a second detection means that detects the jumping up of the document D. The jumping up of the document refers to the deformation of the document being fed so that it is turned up by an external force. The light receiving section S22 is a sensor that receives light emitted from the light emitting section S21. The light emitting section S21 and the light receiving section S22 configure a jump-up detection sensor that detects the jump-up of the document. The light emitting section S21 and the light receiving section S22 are an example of a third sensor.

[0020] The reading unit 40 has a flow reading glass 28, a jump table 29, a reference white board 42, a document table glass 41, a first mirror table 43, a second mirror table 44, a lens 45, and a CCD line sensor 46. A lamp 47 and a mirror 48 are arranged inside the first mirror table 43. Mirrors 49 and 50 are arranged inside the second mirror table 44. The first mirror table 43 and the second mirror table 44 are configured to be movable in the sub-scanning direction (left and right direction in the figure) by wires and drive motors (not shown).

[0021] The image reading device 10 can execute a flow reading mode in which an image of an original D loaded on an original tray 21 is read while the original D is fed by the ADF 20, and a fixed reading mode in which an image of an original placed on an original platen glass 41 is read. The flow reading mode is selected when an original presence / absence sensor S31 detects an original D loaded on the original tray 21, or when the flow reading mode is explicitly instructed by the operation unit 506.

[0022] When the skimming mode is executed, the pickup roller 22 supported by an arm (not shown) descends and contacts the topmost document D on the document tray 21. The document D is then fed by the pickup roller 22 and separated one by one at a separation nip formed by the feed roller 23 and the separation roller 24. The feed roller 23 is made of a rubber material or the like having less friction than the separation roller 24. A torque limiter is disposed in the drive transmission path to the separation roller 24, and the separation roller 24 rotates together with the feed roller 23 when the number of fed documents is one, and does not rotate when the number of fed documents is two or more. Therefore, the documents can be separated one by one by the feed roller 23 and the separation roller 24. The separation roller 24 may be a separation member such as a separation pad having a friction member. The feed roller 23 may also be a conveying member such as a rotatably provided belt.

[0023] The document D fed from the document tray 21 is transported by a transport roller pair 25, and is transported toward the flow-reading glass 28 by a lead roller pair 26. A platen guide roller 27 is disposed in a position facing the flow-reading glass 28. The platen guide roller 27 guides the document D passing through the flow-reading glass 28 so that it does not lift up from the flow-reading glass 28.

[0024] Then, the image on the surface of the original D is read by the reading unit 40 through the flow reading glass 28. Specifically, light from a lamp 47 is irradiated onto the original D being transported, and the reflected light from the original D is guided to a lens 45 by mirrors 48, 49, and 50. The light that passes through the lens 45 is imaged on the light receiving portion of a CCD line sensor 46, photoelectrically converted, and the image information is transmitted to the CPU 81. The reference white board 42 serves as a reference for the reading luminance of the original D. The original D that has passed through the flow reading glass 28 is guided by a jump platform 29 to a pair of lead rollers 30, and is discharged to a discharge tray 32 by a pair of discharge rollers 31.

[0025] On the other hand, the fixed reading mode is selected when the reading unit 40 detects an original D placed on the original table glass 41, or when the fixed reading mode is explicitly instructed by the operation unit 506. In the fixed reading mode, the first mirror table 43 and the second mirror table 44 move along the original table glass 41, and scan the original D with light irradiated by the lamp 47. Image information photoelectrically converted by the light receiving element of the CCD line sensor 46 is transferred to the CPU 81.

[0026] [Control Block] 2 is a control block diagram of the CPU 81 as a control means. The first skew detection sensor S11, the second skew detection sensor S12, the light emitting unit S21, the light receiving unit S22, and the document presence / absence sensor S31 are connected to the CPU 81. The feed motor 84 and the transport motor 85 are connected to the CPU 81 via the 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 CPU 81 is also connected to an operation unit 506 and a storage unit 507. A user can start a copy job and perform various settings by using the operation unit 506.

[0027] 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 succeeding 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, the second skew detection sensor S12 also serves as a post-separation sensor, so that the number of sensors can be reduced and the cost of the product can be kept down.

[0028] [Loading mode settings] The ADF 20 can transport documents in three loading modes: a normal mode, a mixed width mode, and a same width mode. The normal mode is a mode in which multiple documents of the same size or one document are set in the document tray 21 and transported. The mixed width mode is a mode in which multiple documents of different widths are set in the document tray 21 and transported. For example, when documents of different widths such as A5 (width 210 mm) and B5 (width 182 mm) are set together in the document tray 21, the user sets the mixed width mode. When reading images of multiple documents of different widths (mixed width documents), the user moves the first regulating plate 21a and the second regulating plate 21b to match the widest document, and sets the smaller document by abutting it against the second regulating plate 21b at the back (see FIG. 13 described later). The mixed width mode is a mode in which multiple documents of the same width but different lengths in the sheet transport direction are set in the document tray 21 and transported. For example, when documents with the same width but different lengths in the sheet transport direction, such as A5 (width 210 mm) and A4R (width 210 mm), are set together in the document tray 21, the user sets the same-width mixed mode. Note that in the following description, the different-width mixed mode and the same-width mixed mode may be collectively referred to as the mixed mode.

[0029] FIG. 3(a) is an example of a screen for a user to set a copy operation, and FIG. 3(b) is an example of a screen for a user to set a stacking mode. The screen shown in FIG. 3(a) displays a start button 600 for instructing the start of a copy job, a stacking mode setting button 601 for setting a stacking mode, and a bound document detection setting button 602 for setting bound document detection. Here, a "bound document" is a stapled document stack. When the start button 600 is pressed by the user, the image reading device 10 starts an image reading operation. When the stacking mode setting button 601 is pressed by the user, the screen of the display panel 506a transitions to the screen shown in FIG. 3(b).

[0030] The screen shown in Fig. 3(b) displays a normal mode selection section 603, a mixed mode selection section 604, a different width mixed selection section 605, and a same width mixed selection section 606. The different width mixed selection section 605 and the same width mixed selection section 606 are displayed on the screen in response to the mixed mode selection section 604 being pressed by the user. The user can select an appropriate loading mode from the screen of Fig. 3(b) based on the width and length of the documents included in the document stack from which images are to be read. For example, when the user sets a plurality of documents of different widths in the document tray 21, the user presses the different width mixed selection section 605 to set the different width mixed mode.

[0031] [Skew detection sensor] Next, the first skew detection sensor S11 and the second skew detection sensor S12 will be described. FIG. 4 is a top view showing the positions of the first skew detection sensor S11 and the second skew detection sensor S12. The first skew detection sensor S11 and the second skew detection sensor S12 are disposed downstream of the feed roller 23 in the sheet conveying direction. The first skew detection sensor S11 and the second skew detection sensor S12 are disposed side by side in the width direction. That is, the first skew detection sensor S11 and the second skew detection sensor S12 are disposed at the same position in the sheet conveying direction. Although the number of skew detection sensors in this embodiment is two, the number of skew detection sensors may be three or more.

[0032] 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. The CPU 81 also determines that the document is stapled when the amount of skew of the document is large. The CPU 81 determines that the document is stapled when the first skew detection sensor S11 and the second skew detection sensor S12 do not detect the document until a predetermined time has elapsed since one of the first skew detection sensor S11 and the second skew detection sensor S12 detected the document. Then, the CPU 81 stops feeding the document when it determines that the document is stapled. In other words, the CPU 81 stops feeding when the difference in detection timing between the first skew detection sensor S11 and the second skew detection sensor S12 is large. For example, when the second skew detection sensor S12 does not detect the document even after a predetermined time has elapsed since the first skew detection sensor S11 detected the document, the CPU 81 stops feeding. The skew detection process executed by the CPU 81 will be described later.

[0033] [Jump detection sensor] Next, the light emitting unit S21 and the light receiving unit S22 as the jump-up detection sensor will be described. FIG. 15 is a perspective view of the image reading device 10. As shown in FIG. 15, the ADF 20 has a first wall portion 33 and a second wall portion 34 that extend perpendicularly to the support surface that supports the document of the document tray 21. The first wall portion 33 and the second wall portion 34 are a pair of walls that are arranged opposite to each other with the support surface of the document tray 21 in between. The first wall portion 33 is arranged on the front side of the first regulating plate 21a, and the second wall portion 34 is arranged on the back side of the second regulating plate 21b. The light emitting unit S21 is arranged on the first wall portion 33, and the light receiving unit S22 is arranged on the second wall portion. That is, the light emitting unit S21 and the light receiving unit S22 are arranged at an interval between them in the width direction so as to sandwich the support surface of the document tray 21.

[0034] Fig. 5 is a perspective view showing the positions of the light-emitting unit S21 and the light-receiving unit S22. As shown in Fig. 5, the light-emitting unit S21 and the light-receiving unit S22 are disposed vertically above the support surface of the document tray 21. In addition, the light-emitting unit S21 and the light-receiving unit S22 are disposed upstream of the separation nip formed by the feed roller 23 and the separation roller 24 in the sheet conveying direction.

[0035] The CPU 81 can determine whether or not the document is stapled based on a signal from the light receiving unit S22. When the light path from the light emitting unit S21 to the light receiving unit S22 is blocked by the document, the CPU 81 determines that the document is stapled and stops feeding. The process of the jump detection executed by the CPU 81 will be described later.

[0036] [Bound document detection flow] Next, the process of detecting a bound document will be described with reference to a flowchart. Fig. 6 is a flowchart showing the process of document feeding operation executed by the CPU 81. When the power supply to the printer 100 is turned on, the CPU 81 starts the process of the flowchart in Fig. 6.

[0037] First, the CPU 81 determines whether or not a document is loaded on the document tray 21 based on a signal from the document presence / absence sensor S31 (step S101). If there is no document on the document tray 21 (step S101: No), the CPU 81 does not proceed to the next process and waits until a document is loaded on the document tray 21.

[0038] If it is determined that originals are loaded on the original tray 21 (step S101: Yes), it is determined whether or not a user has instructed to start feeding (step S102). If a user has not instructed to start feeding (step S102: No), the CPU 81 does not proceed to the next process and waits until a user instructs to start feeding. If a user has instructed to start feeding (step S102: Yes), the CPU 81 starts feeding the originals (step S103).

[0039] When feeding of the originals is started, the CPU 81 judges whether or not the different widths mixed mode is set (step S104). If the different widths mixed mode is not set (step S104: No), the CPU 81 performs both the jumping detection process (step S105) and the skew detection process (step S106) in parallel. Here, the case where the different widths mixed mode is not set means that the normal mode or the same widths mixed mode is set. If the different widths mixed mode is set (step S104: Yes), the CPU 81 performs only the jumping detection process (step S105) and does not perform the skew detection process. The jumping detection process and the skew detection process will be described later.

[0040] When the process of the jumping detection process or the skew detection process is completed, the CPU 81 judges whether or not skew or jumping of the document has been detected (step S107). If skew or jumping of the document has been detected (step S107: Yes), the CPU 81 stops the feed motor 84 and the transport motor 85 to stop feeding of the document (step S108). If skew or jumping of the document has been detected, the CPU 81 displays a message on the display panel 506a indicating that the document may be stapled.

[0041] If skewing or jumping of the document is not detected (step S107: No), the CPU 81 judges whether the document being transported is the last document based on a signal from the document presence / absence sensor S31 (step S109). If the document being transported is the last document (step S109: Yes), the CPU 81 stops the feed motor 84 and the transport motor 85 (step S108). If the document being transported is not the last document (step S109: No), the process returns to step S103 and starts feeding the next document. The CPU 81 repeats the above process, and when the transport of the last document is completed, the process of the flowchart ends.

[0042] [Bounce detection process] Next, the jump-up detection process, which is step S105 in Fig. 6, will be described. Fig. 7 is a flowchart showing the processing of the jump-up detection process executed by the CPU 81. In the following description, a state in which the light receiving unit S22 receives light from the light emitting unit S21 is called a "non-detection state", and a state in which the light receiving unit S22 does not receive light from the light emitting unit S21 is called a "detection state".

[0043] First, before describing the flow chart of the jump-up detection process, the movement of the document when the jump-up occurs will be described. FIG. 8 is a perspective view showing the movement of the document when the bound document Dst is fed. FIG. 8(a) shows a state in which the bound document Dst is stacked, FIG. 8(b) shows a state in which the bound document Dst is fed to the feed roller 23, and FIG. 8(c) shows a state in which the bound document Dst has jumped up. The bound document Dst is a document stack in which the first document Dst1 and the second document Dst2 are bound by a staple ST. FIG. 9 is a perspective view showing the movement of the document when the normal document D that is not stapled is fed. FIG. 9(a) shows a state in which the normal document D is being transported, and FIG. 9(b) shows a state in which the transported normal document D has passed the second skew detection sensor S12.

[0044] When feeding is started in a state where the bound document Dst is loaded on the document tray 21 as shown in FIG. 8(a), the bound document Dst is conveyed by the pickup roller 22 to the separation nip formed by the feed roller 23 and the separation roller 24. When the bound document Dst reaches the separation nip as shown in FIG. 8(b), the first document Dst1 and the second document Dst2 are conveyed so as to be separated. At this time, the first document Dst1 advances in the sheet conveying direction, whereas the second document Dst2 remains on the document tray 21 by the separation roller 24. However, since the first document Dst1 and the second document Dst2 are bound by the staple ST, the force received from each roller may cause the first document Dst1 to jump up as if it is turned up. When the first document Dst1 jumps up as shown in FIG. 8(c), the light from the light emitting unit S21 hits point A on the first document Dst1, and the light path from the light emitting unit S21 to the light receiving unit S22 is blocked. Therefore, when the light receiving section S22 is in a detection state, the CPU 81 can determine that the document has jumped up.

[0045] On the other hand, when an unstapled normal document D is being transported as shown in Fig. 9(a), the light receiving section S22 is always in a non-detecting state. Then, when the rear end of the document D passes the second skew detection sensor S12 while the light receiving section S22 is in a non-detecting state as shown in Fig. 9(b), the CPU 81 determines that the document has not jumped up.

[0046] FIG. 10 is a perspective view showing the movement of the bound document Dst when the bound document Dst with its trailing end stapled is fed. FIG. 10(a) shows a state in which the bound document Dst is stacked, FIG. 10(b) shows a state in which the bound document Dst is fed to the feed roller 23, and FIG. 10(c) shows a state in which the bound document Dst has jumped up. FIG. 8 shows the leading end of the bound document Dst being stapled, whereas FIG. 10 shows the trailing end of the bound document Dst being stapled. When the bound document Dst with its trailing end stapled as in FIG. 10(a) is fed, the bound document Dst is conveyed without jumping up to the feed roller 23 as in FIG. 10(b). However, since only the first document Dst1 advances in the sheet conveying direction at the separation nip and the second document Dst2 remains in the document tray 21, the stapled trailing end of the bound document Dst jumps up. As a result, the optical path from the light emitting element S21 to the light receiving element S22 is blocked, and the light receiving element S22 enters a detection state. In this manner, even if the position of the staple ST is different, the CPU 81 can detect the jumping up of the document.

[0047] A flowchart of the jump-up detection process will be described below. When the jump-up detection process starts, the CPU 81 judges whether the light receiving unit S22 is in a detection state (step S201). If the light receiving unit S22 is in a non-detection state (step S201: No), the CPU 81 judges whether the second skew detection sensor S12 has changed from ON (a state in which the document is detected) to OFF (a state in which the document is not detected) (step S202). If the second skew detection sensor S12 is ON (step S202: No), the process returns to step S201.

[0048] In step S201, if the light receiving unit S22 is in a detection state (step S201: Yes), the CPU 81 determines that the document has jumped up (step S203) and ends the jumping detection process. In step S203, the CPU 81 records in the memory unit 507 that the document has jumped up. On the other hand, if the second skew detection sensor S12 is turned OFF while the light receiving unit S22 remains in a non-detection state (step S202: Yes), the CPU 81 determines that the document has not jumped up (step S204) and ends the jumping detection process. In step S204, the CPU 81 records in the memory unit 507 that the document has not jumped up.

[0049] As described above, when the light path from the light-emitting unit S21 to the light-receiving unit S22 is blocked by the bound document Dst and the light-receiving unit S22 is in a detection state, the CPU 81 determines that the document has jumped up (the document has been stapled). Then, as described in S107, when the document has jumped up, the CPU 81 stops feeding the document.

[0050] [Skewing detection process] Next, the skew detection process (step S106 in FIG. 6) will be described with reference to a flowchart. FIG.

[0051] First, before describing the flowchart of the skew detection process, the movement of the document when skew occurs will be described. Fig. 12 is a perspective view showing the movement of the document when the bound document Dst is fed. Fig. 12(a) shows a state in which the bound document Dst is stacked, and Fig. 6(b) shows a state in which the bound document Dst is fed and skew occurs.

[0052] When feeding is started in a state where the bound document Dst is loaded on the document tray 21 as shown in FIG. 12(a), the bound document Dst is conveyed by the pickup roller 22 to a separation nip formed by the feed roller 23 and the separation roller 24. When the bound document Dst reaches the separation nip as shown in FIG. 12(b), the first document Dst1 and the second document Dst2 are conveyed so as to be separated. At this time, the first document Dst1 advances in the sheet conveying direction, whereas the second document Dst2 remains on the document tray 21 by the separation roller 24. However, since the first document Dst1 and the second document Dst2 are stapled together by the staple ST, the first document Dst1 may rotate around the staple ST. At this time, the side of the document Dst1 stapled together by the staple ST is not conveyed, so the first skew detection sensor S11 is turned OFF. On the other hand, the side of the document Dst1 that is not stapled with the staple ST is transported downstream, so the second skew detection sensor S12 is turned ON. In this way, the CPU 81 can determine whether the document is skewed based on the difference in timing when the two skew detection sensors are turned ON.

[0053] A flowchart of the skew detection process will be described below. First, the CPU 81 judges whether the first skew detection sensor S11 is ON (step S301). If the first skew detection sensor S11 is not ON (step S301: No), the CPU 81 judges whether the second skew detection sensor S12 is ON (step S302). If the second skew detection sensor S12 is ON in step S302, the CPU 81 judges whether the first skew detection sensor S11 is ON (step S303). That is, in step S303, after the second skew detection sensor S12 is ON in step S302, the CPU 81 judges whether the first skew detection sensor S11 is ON. Here, if the first skew detection sensor S11 is OFF (step S303: No), the CPU 81 judges whether a predetermined time Tth [ms] has elapsed since the second skew detection sensor S12 was turned ON (step S304). When a predetermined time Tth [ms] has elapsed since the second skew detection sensor S12 was turned on and the first skew detection sensor S11 was kept OFF (step S304: Yes), the CPU 81 determines that the document has been skewed (step S305). In step S305, the CPU 81 records in the memory unit 507 that the document has been skewed.

[0054] On the other hand, if the first skew detection sensor S11 turns ON before the predetermined time Tth [ms] has elapsed since the second skew detection sensor S12 turned ON (step S303: Yes), the CPU 81 waits until the second skew detection sensor S12 turns OFF (step S308). If the second skew detection sensor S12 turns OFF in step S308, the CPU 81 determines that skew has not occurred (step S309) and ends the skew detection process. In step S309, the CPU 81 records in the memory unit 507 that skew of the document has not occurred.

[0055] In step S301, if the first skew detection sensor S11 is ON (step S301: Yes), the CPU 81 judges whether the second skew detection sensor S12 is ON (step S306). That is, in step S306, after the first skew detection sensor S11 is ON in step S301, the CPU 81 judges whether the second skew detection sensor S12 is ON. Here, if the second skew detection sensor S12 is OFF (step S306: No), the CPU 81 judges whether a predetermined time Tth [ms] has elapsed since the first skew detection sensor S11 was ON (step S307). If the predetermined time Tth [ms] has elapsed since the first skew detection sensor S11 was ON and the second skew detection sensor S12 was OFF (step S307: Yes), the CPU 81 judges that skew of the document has occurred (step S305).

[0056] On the other hand, if the second skew detection sensor S12 turns ON before the predetermined time Tth [ms] has elapsed since the first skew detection sensor S11 turned ON (step S306: Yes), the process proceeds to step S308. If the second skew detection sensor S12 turns OFF in step S308, the CPU 81 determines that skew has not occurred (step S309) and ends the skew detection process.

[0057] Here, the predetermined time Tth is a value determined according to the transport speed, and is, for example, 30 ms. However, the value of the predetermined time Tth is not limited to this. In addition, the value of the predetermined time Tth in step S304 may be different from that in step S307.

[0058] As described above, when one of the first skew detection sensor S11 and the second skew detection sensor S12 does not detect the original within a predetermined time after the other detects the original, the CPU 81 determines that the original has been skewed (the original has been stapled). Then, as described in S107, when the original has been skewed, the CPU 81 stops feeding the original.

[0059] [Original placement in mixed width mode] Next, a method for setting documents in the different width mixed mode will be described. Fig. 13(a) is a top view of the document tray 21 in a state where documents are stacked in the different width mixed mode. Fig. 13(b) is a top view showing a state where a short document is fed in the different width mixed mode. Figs. 13(a) and (b) show a case where a small document D1 and a large document D2 are stacked on the document tray 21.

[0060] As described above, the different widths mixed mode is a mode in which a plurality of documents with different widths are stacked on the document tray 21 and fed. As shown in FIG. 13(a), in the different widths mixed mode, the first regulating plate 21a and the second regulating plate 21b are moved by the user to match the widest document D2. That is, the wide document D2 is in a state in which the front end in the width direction abuts against the first regulating plate 21a and the rear end abuts against the second regulating plate 21b. On the other hand, the small width document D1 is set based on the rear side second regulating plate 21b. That is, the small width document D1 is in a state in which the front end in the width direction is separated from the first regulating plate 21a and the rear end abuts against the second regulating plate 21b. When the user selects the different widths mixed mode on the operation unit 506, a screen is displayed on the display panel 506a to prompt the user to set all documents in alignment with the rear side second regulating plate 21b.

[0061] As shown in Fig. 13(b), when feeding of a mixed document with different widths is started, the document D1 with a smaller width may pass the detection position of the second skew detection sensor S12 but may not pass the detection position of the first skew detection sensor S11. In such a case, when the above-mentioned skew detection process is executed, the CPU 81 may erroneously detect the presence of skew. This is because the predetermined time Tth [ms] has passed since the second skew detection sensor S12 detected the document and the first skew detection sensor S11 was kept OFF (step S304: Yes).

[0062] However, in this embodiment, when the different widths mixed mode is set, the CPU 81 executes only the jumping detection process without executing the skew detection process. This makes it possible to prevent the CPU 81 from erroneously detecting that the original has been skewed in the different widths mixed mode. Furthermore, since staple detection by the jumping detection process is possible even in the different widths mixed mode, it is possible to prevent the original from being damaged by feeding the staple detection even in the different widths mixed mode.

[0063] In this embodiment, when the different width mixed sheet mode is set, the CPU 81 does not execute the skew detection process. However, the CPU 81 may be configured to execute the skew detection process in the different width mixed sheet mode and ignore the skew detection result. That is, in the different width mixed sheet mode, even if the skew of the original is detected by the skew detection process, the CPU 81 may be configured to continue feeding. Also, the CPU 81 may control not to supply power to the first skew detection sensor S11 and the second skew detection sensor S12 in the different width mixed sheet mode.

[0064] <Second embodiment> Next, a second embodiment of the present invention will be described. The basic configuration of the printer 100 according to the second embodiment is the same as that of the first embodiment, so the description will be omitted. Fig. 14 is an example of a screen for a user to set bound document detection. When the bound document detection setting button 602 is pressed by the user on the screen of Fig. 3(a) described above, the screen of the display panel 506a transitions to the screen shown in Fig. 14.

[0065] The screen in Fig. 14 displays a skew detection setting section 607 and a jump detection setting section 608. The skew detection setting section 607 allows the user to select whether skew detection in the ADF 20 is ON (enabled) or OFF (disabled) as a first setting. When ON is selected in the skew detection setting section 607, the CPU 81 stops feeding if skew of the original occurs based on the result of the skew detection process described above. When OFF is selected in the skew detection setting section 607, the CPU 81 ignores the result of the skew detection process and continues feeding even if it determines that skew of the original has occurred.

[0066] The jump-up detection setting section 608 can select whether to turn the jump-up detection in the ADF 20 ON (enabled) or OFF (disabled) as the second setting. When ON is selected in the jump-up detection setting section 608, the CPU 81 stops feeding if the original jumps up based on the result of the jump-up detection process described above. When OFF is selected in the jump-up detection setting section 608, the CPU 81 ignores the result of the jump-up detection process and continues feeding even if it determines that the original jumps up.

[0067] The CPU 81 may be configured not to execute the skew detection process when OFF is selected in the skew detection setting unit 607. The CPU 81 may be configured not to execute the jump-up detection process when OFF is selected in the jump-up detection setting unit 608.

[0068] In this way, if the configuration allows the setting of bound document detection, the user can arbitrarily select whether or not to execute skew detection and jumping detection depending on the size of the document to be fed. For example, if the document to be read is a mixed document of different widths, the user sets skew detection to OFF and jumping detection to ON. This makes it possible to prevent the CPU 81 from erroneously detecting that a document has been skewed in the mixed document mode in the same way as in the first embodiment. Furthermore, since staple detection by the jumping detection process is possible even in the mixed document mode, it is possible to prevent documents from being damaged by feeding staple detection even in the mixed document mode.

[0069] Also, for example, when a document with a large curl is loaded on the document tray 21, the light path from the light-emitting unit S21 to the light-receiving unit S22 may be blocked by the curled portion of the document, and the CPU 81 may erroneously detect that the document has jumped up. However, in this embodiment, the user can arbitrarily set the bound document detection according to the state of the document, so that it is possible to reduce erroneous detection. [Explanation of symbols]

[0070] 10 Image reader 20 ADF 40 Reading Unit 81 CPU 100 Printers S11 First skew detection sensor S12 Second skew detection sensor S21 Light emitting part S22 Light receiving section

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 first detection means for detecting the skewness of the sheet being fed by the feeding means, A second detection means for detecting the upward movement of the sheet being fed by the aforementioned feeding means, A control means that stops feeding by the feeding means when the first detection means detects that the sheet is skewed, and when the second detection means detects that the sheet is bouncing up. A setting means for setting a mixed-width loading mode in which multiple sheets of different widths are loaded into the loading section, Equipped with, When the mixed loading mode with different widths is set by the setting means, the control means does not stop feeding based on the detection of skew by the first detection means, but does stop feeding based on the detection of bouncing by the second detection means. A sheet conveying device characterized by the following features.

2. The first detection means includes a first sensor for detecting a sheet being fed by the feeding means, and a second sensor arranged side by side in the width direction with the first sensor for detecting a sheet being fed by the feeding means. The control means stops feeding by the feeding means if a predetermined time elapses after one of the first and second sensors detects a sheet, and the other sensor does not detect a sheet. The sheet conveying device according to feature 1.

3. Based on the detection of the rear end of the preceding sheet by the second sensor, the control means starts feeding the following sheet that follows the preceding sheet. The sheet conveying device according to feature 2.

4. The second detection means includes a light-emitting unit and a light-receiving unit positioned above the loading unit, The control means stops feeding by the feeding means if the light path from the light-emitting unit to the light-receiving unit is blocked by the sheet after feeding by the feeding means has started. The sheet conveying device according to feature 1.

5. The setting means can set the mixed loading mode for different widths and the mixed loading mode for the same widths in which multiple sheets with the same width but different lengths in the sheet transport direction are loaded into the loading section. When the same-width mixed loading mode is set by the setting means, the control means performs both stopping the feeding based on the detection of skew by the first detection means and stopping the feeding based on the detection of bouncing by the second detection means. The sheet conveying device according to feature 1.

6. The device has a display means that displays a message indicating that the sheet loaded in the loading section may be a bound document when the first detection means detects skewness and when the second detection means detects upward movement. The sheet conveying device according to feature 1.

7. 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 first detection means for detecting the skewness of the sheet being fed by the feeding means, A second detection means for detecting the upward movement of the sheet being fed by the aforementioned feeding means, A control means that determines that the sheet loaded in the loading section is a bound document when the first detection means detects that the sheet is skewed, and when the second detection means detects that the sheet is flipped up. A setting means for setting a mixed-width loading mode in which multiple sheets of different widths are loaded into the loading section, Equipped with, When the mixed-width format mode is set by the setting means, the control means does not perform binding document determination based on the detection of skew by the first detection means, but instead performs binding document determination based on the detection of flip-up by the second detection means. A sheet conveying device characterized by the following features.

8. 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 first detection means includes a first sensor for detecting a sheet being fed by the feeding means, and a second sensor arranged alongside the first sensor in the width direction of the sheet perpendicular to the feeding direction of the sheet by the feeding means, and for detecting a sheet being fed by the feeding means. A second detection means including a light-emitting unit and a light-receiving unit positioned above the loading unit in the vertical direction, A control means for stopping feeding by the feeding means in the case where the other of the first and second sensors does not detect the sheet after a predetermined time has elapsed since one of the first and second sensors detected the sheet, or in the case where the light path from the light-emitting unit to the light-receiving unit is blocked by the sheet, A setting means for setting a mixed-width loading mode in which multiple sheets of different widths are loaded into the loading section, Equipped with, When the mixed loading mode with different widths is set by the setting means, the control means does not stop feeding based on the first detection means, but does stop feeding based on the second detection means. A sheet conveying device characterized by the following features.

9. 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 first detection means for detecting the skewness of the sheet being fed by the feeding means, A second detection means for detecting the upward movement of the sheet being fed by the aforementioned feeding means, A control means that stops feeding by the feeding means when the first detection means detects that the sheet is skewed, and when the second detection means detects that the sheet is bouncing up, A setting means for setting a first setting to enable or disable the detection of sheet skew by the first detection means, and a second setting to enable or disable the detection of sheet bounce-up by the second detection means, Equipped with, A sheet conveying device characterized by the following features.

10. A sheet conveying device according to any one of claims 1 to 9, A reading means for reading an image of a sheet being transported by the aforementioned sheet transport device, Equipped with, An image reading device characterized by the following:

11. The image reading device according to claim 10, An image forming means that forms an image on a recording material based on the image information of the sheet read by the aforementioned image reading device, Equipped with, An image forming apparatus characterized by the following:

Images