Automatic document conveying device, and image forming device

Abstract

To provide an automatic document conveying device capable of detecting a fastener with which a document is provided.SOLUTION: An automatic document conveying device according to one embodiment of the present invention comprises: a document placement part for placing a document; a document conveyance part for conveying the document placed at the document placement part along a document conveyance passage; one or more sound generation parts each that are protruded or recessed on a surface of the document conveyance passage, that are provided on the document conveyance passage; a sound collection part for collecting sound when the one or more sound generation parts come in contact with a fastener attached to the document; and a prediction part for predicting presence / absence of the fastener, based on the sound collected by the sound collection part. The sound generation part is continuously or intermittently provided over the other end from one end in a width direction of the document conveyance passage.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to an automatic document feeder and an image forming apparatus. [Background technology]

[0002] Conventionally, in an automatic document feeder that continuously feeds multiple sheet-like documents placed on a document tray one by one toward an image reading position of a scanner serving as a document reading device, it has been considered to determine jams (paper jams) and wrinkles by sound. For example, Patent Document 1 discloses a medium feeding device that includes a sound detection means provided downstream of the feeding means in the feeding direction and determines a jam when the sound level exceeds a threshold. Patent Document 1 also discloses a technology in which the medium feeding device includes contactors and detects wrinkles by detecting the sound generated by contact between the medium and the contactors. Summary of the Invention [Problem to be solved by the invention]

[0003] However, the media feeding device described in Patent Document 1 does not consider the case where a document has fasteners such as clips attached to it, which could cause a jam. When a document with a fastener attached is transported, the fastener cannot be detected because no sound is produced when it passes next to the contact.

[0004] SUMMARY OF THE INVENTION It is an object of one aspect of the present invention to provide an automatic document feeder that can detect a fastener attached to a document. [Means for solving the problem]

[0005] One aspect of the automatic document feeder of the present invention comprises a document loading section for loading a document, a document transport section for transporting the document loaded on the document loading section along a document transport path, one or more sound generating sections provided on the document transport path and having a convex or concave shape relative to the surface of the document transport path, a sound collecting section for collecting sound when the sound generating section comes into contact with a fastener attached to the document, and a prediction section for predicting the presence or absence of the fastener based on the sound collected by the sound collecting section, and the sound generating sections are provided continuously or intermittently across the width of the document transport path from one end to the other. [Effects of the Invention]

[0006] According to one aspect of the present invention, it is possible to provide an automatic document feeder that can detect a fastener attached to a document. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a schematic diagram illustrating the configuration of an image forming apparatus according to an embodiment of the present invention. [Figure 2] FIG. 2 is a partial enlarged view showing a part of an image forming unit according to an embodiment of the present invention. [Figure 3] 2 is a partial enlarged view showing a part of a tandem portion consisting of four image forming units in an image forming section according to one embodiment of the present invention. FIG. [Figure 4] 1 is a perspective view showing a scanner and an ADF according to an embodiment of the present invention. [Figure 5] FIG. 1 is a perspective view showing an ADF according to an embodiment of the present invention. [Figure 6] FIG. 1 is a schematic configuration diagram showing an ADF according to an embodiment of the present invention. [Figure 7] FIG. 6 is a partially enlarged view showing the main part of FIG. 5. [Figure 8] FIG. 2 is a top view of a portion of a document transport path according to an embodiment of the present invention. [Figure 9] FIG. 2 is a perspective view showing an example of a sound generating unit according to an embodiment of the present invention. [Figure 10]FIG. 10 is a perspective view showing a first modified example of a sound generating section according to an embodiment of the present invention. [Figure 11] FIG. 10 is a schematic diagram illustrating an example of a document with a fastener attached thereto. [Figure 12] 12A to 12C are diagrams illustrating the state of conveyance of the original shown in FIG. 11. [Figure 13] FIG. 10 is a schematic diagram showing another example of a document with a fastener attached thereto. [Figure 14] 14 is a diagram illustrating the state of conveyance of the original shown in FIG. 13. FIG. [Figure 15] FIG. 10 is a perspective view showing a second modified example of the sound generating section according to one embodiment of the present invention. [Figure 16] FIG. 10 is a perspective view showing a third modified example of the sound generating section according to one embodiment of the present invention. [Figure 17] FIG. 10 is a perspective view showing a fourth modified example of the sound generating section according to one embodiment of the present invention. [Figure 18] FIG. 10 is a top view of a portion of a first modified example of a document transport path according to an embodiment of the present invention. [Figure 19] 18 as viewed from the upstream side in the transport direction. [Figure 20] FIG. 19 is a side view of FIG. 18. [Figure 21] FIG. 10 is a perspective view showing a fifth modified example of the sound generating section according to one embodiment of the present invention. [Figure 22] FIG. 10 is a top view of a portion of a second modified example of the document transport path according to an embodiment of the present invention. [Figure 23] FIG. 23 is an enlarged perspective view of a part of FIG. 22. [Figure 24] 10 is a top view of a part of a document transport path in another example of an ADF according to an embodiment of the present invention. FIG. [Figure 25] 2 is a block diagram showing a part of an electric circuit of the image forming apparatus according to the embodiment of the present invention. FIG. [Figure 26] 10 is a flowchart showing a fastener determination process performed by a controller according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0008] An image forming apparatus according to an embodiment of the present invention will be described below, in which the image forming apparatus is applied to an electrophotographic copying machine as an example.

[0009] First, the basic configuration of an image forming apparatus according to an embodiment will be described. Fig. 1 is a schematic diagram showing an image forming apparatus 100 according to an embodiment of the present invention. As shown in Fig. 1, the image forming apparatus 100 includes an image forming unit 1 that forms images, a sheet supply device 40, and an image reading system 50. The image reading system 50 includes a scanner 150 as an image reading device fixed above the image forming unit 1, and an automatic document feeder (hereinafter referred to as ADF) 51 supported by the scanner 150.

[0010] The sheet supply device 40 has two paper feed cassettes 42 arranged in multiple stages in a paper bank 41, a feed roller 43 that feeds recording sheets from the paper feed cassettes, a separation roller 45 that separates the fed recording sheets one by one, etc. It also has a plurality of conveyance roller pairs 46 that convey the recording sheets to the paper feed path 37 that serves as a conveyance path for the image forming unit 1.

[0011] The paper feed cassette 42 contains a stack of recording sheets. The topmost recording sheet is pressed against the feed roller 43. When the feed roller 43 rotates, the topmost recording sheet of the sheet stack is fed out of the paper feed cassette 42.

[0012] Near the paper feed cassette 42, the first conveying roller of the conveying roller pair 46 and the second conveying roller disposed to the side of it (to the right in the drawing) come into contact with each other to form a conveying nip. In addition, a separation roller 45 is disposed below the first conveying roller and comes into contact with the first conveying roller from below to form a separation conveying nip.

[0013] The recording sheet sent out from the paper feed cassette 42 by the rotational drive of the delivery roller 43 enters a separation and conveyance nip formed by the abutment between the first conveyance roller of the conveyance roller pair 46 and the separation roller 45 disposed below it. In this separation and conveyance nip, the first conveyance roller abutting the upper surface of the recording sheet rotates counterclockwise in the drawing, imparting a conveying force to the recording sheet from the paper feed cassette 42 side toward the feed path 44 side. In response to this, the separation roller 45 abutting the lower surface of the recording sheet rotates counterclockwise in the drawing, imparting a conveying force to the recording sheet from the feed path 44 side toward the paper feed cassette 42 side, attempting to return the recording sheet to the paper feed cassette 42.

[0014] When only one recording sheet is fed from the paper feed cassette 42, the first conveying roller and separation roller 45 apply conveying forces in opposite directions to the recording sheet at the separation conveying nip. This causes a load exceeding a predetermined threshold to be applied to the drive transmission system of the separation roller 45. This activates a torque limiter disposed in the drive transmission system, cutting off the transmission of the drive force from the DC brushless motor (not shown) to the separation roller 45. As a result, the separation roller 45 rotates along with the recording sheet being conveyed by the first conveying roller, and the recording sheet is discharged from the separation conveying nip toward the feeding path 44.

[0015] On the other hand, when a plurality of overlapping recording sheets are fed out from the paper feed cassette 42, the first conveying roller imparts a conveying force to the topmost recording sheet in a direction from the paper feed cassette 42 toward the feed path 44 at the separation conveying nip. The topmost recording sheet is then fed out from the separation conveying nip toward the feed path 44. In response to this, the separation roller imparts a conveying force to the lower recording sheet in a direction from the feed path 44 toward the paper feed cassette, causing the lower recording sheet to return from the separation conveying nip toward the paper feed cassette 42. As a result, the topmost recording sheet is separated from the other recording sheets at the separation conveying nip and fed out to the feed path 44 as a single sheet.

[0016] The recording sheet that has entered the feeding path 44 enters the feeding nip of the pair of feeding rollers 46 and is given a feeding force from the lower side to the upper side in the vertical direction. As a result, the recording sheet is conveyed in the feeding path 44 toward the paper feeding path 37 of the image forming unit 1.

[0017] The image forming unit 1 includes an optical writing device 2 and four imaging units 3K, 3Y, 3M, and 3C that form toner images of black, yellow, magenta, and cyan (K, Y, M, and C). It also includes a transfer unit 24, a paper transport unit 28, a pair of registration rollers 33, a fixing device 34, a switchback device 36, and a paper feed path 37. Light sources such as laser diodes or LEDs (not shown) arranged within the optical writing device 2 are driven to irradiate laser light L onto the four drum-shaped photoconductors 4K, Y, M, and C. This irradiation forms electrostatic latent images on the surfaces of the photoconductors 4K, Y, M, and C, which are then developed into toner images through a predetermined development process.

[0018] Fig. 2 is a partially enlarged view showing a part of the image forming section 1 according to one embodiment of the present invention, and Fig. 3 is a partially enlarged view showing a part of a tandem section consisting of four imaging units 3K, Y, M, and C in the image forming section 1 according to one embodiment of the present invention. Note that the four imaging units 3K, Y, M, and C have almost the same configuration except for the toner colors they use, and therefore the subscripts K, Y, M, and C attached to each reference number are omitted in Fig. 3.

[0019] Each of the imaging units 3K, Y, M, and C has a photoconductor and various devices disposed around it supported on a common support as a single unit, and is detachable from the main body of the image forming section 1. Taking the black imaging unit 3K as an example, it has a charging device 23, a developing device 6, a drum cleaning device 15, a static elimination lamp 22, etc., around the photoconductor 4. In the image forming apparatus 100, the four imaging units 3K, Y, M, and C are arranged facing each other along the endless movement direction of the intermediate transfer belt 25, which will be described later, in a so-called tandem configuration.

[0020] The photoreceptor 4 is a drum-shaped member made of a base tube such as aluminum, on which a photosensitive layer is formed by applying an organic photosensitive material having photosensitivity, although an endless belt-shaped member may also be used.

[0021] The developing device 6 is configured to develop a latent image using a two-component developer containing a magnetic carrier and non-magnetic toner (not shown). The developing device 6 has an agitating section 7 that agitates and transports the two-component developer contained therein and supplies it to the developing sleeve 12, and a developing section 11 that transfers the toner in the two-component developer carried on the developing sleeve 12 to the photoconductor 4.

[0022] The stirring section 7 is located at a lower position than the developing section 11, and includes two transport screws 8 arranged parallel to each other, a partition plate provided between these screws, and a toner concentration sensor 10 provided on the bottom surface of the developing case 9.

[0023] The developing unit 11 includes a developing sleeve 12 that faces the photosensitive drum 4 through the opening of the developing case 9, a magnet roller 13 that is non-rotatably mounted inside the developing sleeve 12, and a doctor blade 14 that brings its tip close to the developing sleeve 12. The developing sleeve 12 is a non-magnetic, rotatable cylinder. The magnet roller 13 has multiple magnetic poles that are aligned in sequence from the position facing the doctor blade 14 toward the direction of rotation of the sleeve. These magnetic poles each apply a magnetic force to the two-component developer on the sleeve at a predetermined position in the direction of rotation. This attracts and carries the two-component developer sent from the agitating unit 7 to the surface of the developing sleeve 12, forming a magnetic brush on the sleeve surface along the magnetic field lines.

[0024] As the developing sleeve 12 rotates, the magnetic brush is regulated to an appropriate layer thickness as it passes opposite the doctor blade 14, and then transported to the development zone opposite the photoreceptor 4. The toner is then transferred to the electrostatic latent image by the potential difference between the developing bias applied to the developing sleeve 12 and the electrostatic latent image on the photoreceptor 4, contributing to development. As the developing sleeve 12 rotates, the toner returns to the development section 11, where it is separated from the sleeve surface by the influence of the repulsive magnetic field formed between the magnetic poles of the magnet roller 13 and then returned to the agitation section 7. In the agitation section 7, an appropriate amount of toner is replenished to the two-component developer based on the detection results of the toner concentration sensor 10. Instead of using a two-component developer, the developing device 6 may use a single-component developer that does not contain a magnetic carrier.

[0025] The drum cleaning device 15 used here is one that presses a cleaning blade 16 made of an elastic material against the photoreceptor 4, but other types may also be used. In order to improve cleaning performance, this example uses a type that has a contact-conductive fur brush 17 whose outer circumferential surface contacts the photoreceptor 4 and that is rotatable in the direction of the arrow in the figure.

[0026] The fur brush 17 also serves to scrape lubricant from a solid lubricant (not shown) and powder it onto the surface of the photoreceptor 4. A metal electric field roller 18, which applies a bias to the fur brush 17, is rotatable in the direction indicated by the arrow in the figure, and the tip of a scraper 19 is pressed against the metal electric field roller 18. The toner adhering to the fur brush 17 is transferred to the electric field roller 18, which rotates in a counter-direction relative to the fur brush 17 and to which a bias is applied. After being scraped off the electric field roller 18 by the scraper 19, the toner falls onto a collection screw 20. The collection screw 20 transports the collected toner toward the end of the drum cleaning device 15 in a direction perpendicular to the plane of the drawing and delivers it to an external recycling conveying device 21. The recycling conveying device 21 sends the delivered toner to the developing device 6 for recycling.

[0027] The static elimination lamp 22 eliminates static electricity from the photoconductor 4 by irradiating it with light. The surface of the photoconductor 4 from which static electricity has been removed is uniformly charged by the charging device 23, and then optical writing processing is performed by the optical writing device 2. The charging device 23 uses a charging roller to which a charging bias is applied, which rotates while being in contact with the photoconductor 4. A scorotron charger or the like that charges the photoconductor 4 without contact may also be used.

[0028] 2, K, Y, M, and C toner images are formed by the process described above on the photoconductors 4K, Y, M, and C of the four imaging units 3K, Y, M, and C. A transfer unit 24 is disposed below the four imaging units 3K, Y, M, and C.

[0029] The transfer unit 24 moves the intermediate transfer belt 25, which is stretched by multiple rollers, endlessly in a clockwise direction in the figure while contacting the photoconductors 4K, Y, M, and C. This forms primary transfer nips for K, Y, M, and C where the photoconductors 4K, Y, M, and C contact the endless intermediate transfer belt 25. Near the primary transfer nips for K, Y, M, and C, primary transfer rollers 26K, Y, M, and C disposed inside the belt loop press the intermediate transfer belt 25 toward the photoconductors 4K, Y, M, and C. A primary transfer bias is applied to each of these primary transfer rollers 26K, Y, M, and C by a power source (not shown). This forms a primary transfer electric field in the primary transfer nips for K, Y, M, and C that electrostatically transfers the toner images on the photoconductors 4K, Y, M, and C toward the intermediate transfer belt 25.

[0030] As the intermediate transfer belt 25 moves endlessly clockwise in the drawing, it passes through the primary transfer nips for K, Y, M, and C in sequence, and toner images are sequentially superimposed and primarily transferred at each primary transfer nip onto the front surface of the intermediate transfer belt 25. As a result of this superimposed primary transfer, a four-color superimposed toner image (hereinafter referred to as a four-color toner image) is formed on the front surface of the intermediate transfer belt 25.

[0031] Below the transfer unit 24 in the figure, there is provided a paper transport unit 28 that moves an endless paper transport belt 29 by stretching it between a drive roller 30 and a secondary transfer roller 31. The intermediate transfer belt 25 and the paper transport belt 29 are sandwiched between the secondary transfer roller 31 itself and a lower tension roller 27 of the transfer unit 24. This forms a secondary transfer nip where the front surface of the intermediate transfer belt 25 and the front surface of the paper transport belt 29 come into contact with each other. A secondary transfer bias is applied to the secondary transfer roller 31 by a power source (not shown). Meanwhile, the lower tension roller 27 of the transfer unit 24 is grounded. This forms a secondary transfer electric field in the secondary transfer nip.

[0032] A pair of registration rollers 33 is disposed on the right side of this secondary transfer nip in the drawing. A registration roller sensor (not shown) is disposed near the entrance of the registration nip of the pair of registration rollers 33. When a recording sheet is conveyed from a sheet supply device (not shown) toward the pair of registration rollers 33, the conveyance of the recording sheet is temporarily stopped after a predetermined time has passed since the leading edge of the recording sheet was detected by the registration roller sensor, and the leading edge of the recording sheet abuts against the registration nip of the pair of registration rollers 33.

[0033] When the leading edge of the recording sheet strikes the registration nip, the pair of registration rollers 33 resume roller rotation just in time to synchronize the recording sheet with the four-color toner image on the intermediate transfer belt 25, sending the recording sheet to the secondary transfer nip. Within the secondary transfer nip, the four-color toner image on the intermediate transfer belt 25 is transferred all at once to the recording sheet by the action of the secondary transfer electric field and nip pressure, and combined with the white of the recording sheet, forms a full-color image. After passing through the secondary transfer nip, the recording sheet separates from the intermediate transfer belt 25 and is transported to the fixing device 34 as it moves endlessly while being held on the front surface of the paper transport belt 29.

[0034] After passing through the secondary transfer nip, residual toner that was not transferred to the recording sheet at the secondary transfer nip adheres to the surface of the intermediate transfer belt 25. This residual toner is scraped off and removed by a belt cleaning device that contacts the intermediate transfer belt 25.

[0035] The recording sheet conveyed to the fixing device 34 has the full-color image fixed thereon by pressure and heat, and is then sent from the fixing device 34 to a pair of paper discharge rollers 35 and then discharged outside the machine.

[0036] As shown in Figure 1, a switchback device 36 is disposed below the paper transport unit 28 and the fixing device 34. This causes a switching claw to switch the path of the recording sheet, which has undergone image fixing on one side, to the recording sheet inverting device side, where it is inverted and enters the secondary transfer nip again. The other side then undergoes secondary image transfer and fixing, and is then discharged onto the paper output tray.

[0037] Scanner 150, which is fixed on image forming unit 1, has a movable reading unit 152. Scanner 150 and ADF 51 each have a fixed reading unit. Mobile reading unit 152 is disposed directly below second contact glass 155, which is fixed to the upper wall of the casing of scanner 150 and will be described later, so as to come into contact with document MS, and can move an optical system, which is made up of a light source, a reflecting mirror, etc., from left to right in the drawing. As the optical system moves from left to right in the drawing, light emitted from the light source is reflected by a document (not shown) placed on second contact glass 155, passes through multiple reflecting mirrors, and is then received by image reading sensor 153, which is fixed to the scanner body.

[0038] Meanwhile, the fixed reading unit is comprised of a first-side fixed reading unit 151 disposed inside the scanner 150 and a second-side fixed reading unit (not shown) disposed inside the ADF 51. The first-side fixed reading unit 151, which includes a light source, a reflecting mirror, an image reading sensor such as a CCD, and the like, is disposed directly below a first contact glass 154 (described later) fixed to the upper wall of the casing of the scanner 150 so as to come into contact with the original MS. When a sheet-like original MS transported by the ADF 51 (described later) passes over the first contact glass 154, light emitted from the light source is sequentially reflected by the original surface, passes through multiple reflecting mirrors, and is received by the image reading sensor. This allows the first side of the original MS to be scanned without moving the optical system consisting of the light source, reflecting mirrors, and the like. The second-side fixed reading unit scans the second side of the original MS after it has passed the first-side fixed reading unit 151. The original MS is a sheet-like material such as paper or film.

[0039] Fig. 4 is a perspective view showing scanner 150 and ADF 51 according to an embodiment of the present invention, Fig. 5 is a perspective view of ADF 51 according to an embodiment of the present invention, and Fig. 6 is a schematic configuration diagram showing ADF 51 according to an embodiment of the present invention. ADF 51 is disposed above scanner 150. As shown in Figs. 4 to 6, ADF 51 includes an original placement unit 53a on which an original MS to be read is placed, and an original transport unit 54 that transports original MS placed on original placement unit 53a along original transport path 203. Original placement unit 53a may be an original placement table.

[0040] The ADF 51 may include a document stacking table 55 for stacking the scanned documents MS. Specifically, the ADF 51 includes a main body cover 52, which may include a document placement section 53a and a document transport section 54.

[0041] As shown in FIG. 4, the ADF 51 is supported by hinges 159 fixed to the scanner 150 so as to be able to swing up and down. This swinging movement allows the ADF 51 to move like a door, exposing a first contact glass 154 and a second contact glass 155 on the top surface of the scanner 150 when it is open. In the case of single-sided bound documents, such as a book bound at one corner of a stack of documents, the documents cannot be separated one by one and therefore cannot be transported by the ADF. Therefore, in the case of single-sided bound documents, the ADF 51 is opened as shown in FIG. 4, and the single-sided bound document with the page to be read open is placed face down on the second contact glass 155, and the ADF is then closed. The image of that page is then read by the moving reading unit 152 of the scanner 150, as shown in FIG. 1.

[0042] On the other hand, in the case of a stack of multiple independent documents MS, the documents MS can be automatically transported one by one by the ADF 51, and the first-side fixed reading unit 151 in the scanner 150 and the second-side fixed reading unit in the ADF 51 can sequentially read the documents. In this case, after the document stack is placed on the document placing unit 53a, the copy start button 158 is pressed. The ADF 51 then sends the documents MS of the document stack placed on the document placing unit 53a from top to bottom into the document transport unit 54, and transports them toward the document stack table 55 while inverting them. During this transport process, immediately after inverting the document MS, it passes directly above the first-side fixed reading unit 151 of the scanner 150. At this time, the image of the first side of the document MS is read by the first-side fixed reading unit 151 of the scanner 150.

[0043] 6, the ADF 51 includes a document setting unit A, a separation feeding unit B, a registration unit C, a turn unit D, a first reading conveyance unit E, a second reading conveyance unit F, a paper discharge unit G, a stack unit H, etc. The ADF 51 also includes a document transport path 203 for transporting the document MS from the document placing unit 53a toward the first-side fixed reading unit 151, which is the image reading position. That is, the document transport unit 54 includes the document setting unit A, separation feeding unit B, a registration unit C, the turn unit D, the first reading conveyance unit E, the second reading conveyance unit F, the paper discharge unit G, and the document transport path 203.

[0044] The document setting section A has a document placing section 53a on which a stack of documents MS is set. The separation and feeding section B separates and feeds each document MS from the set stack of documents MS. The registration section C temporarily bumps against the fed documents MS to align them and then send them out. The turning section D has a curved conveying section that is curved in a C shape, and turns the documents MS upside down while folding them back within this curved conveying section.

[0045] The first reading and conveying unit E conveys the original MS on the first contact glass 154, while causing the first side fixed reading unit 151, which is disposed inside the scanner 150 below the first contact glass 154, to read the first side of the original MS. The second reading and conveying unit F conveys the original MS below the second fixed reading unit 95, while causing the second side of the original MS to be read by the second fixed reading unit 95. The paper discharge unit G discharges the original MS, after the images on both sides have been read, toward the stack unit H. The stack unit H stacks the original MS on the original stack table 55.

[0046] The leading edge of the original MS is placed on the movable original table 53b, which can swing in the directions of arrows a and b in FIG. 6 depending on the thickness of the stack of originals MS, and the trailing edge of the original MS is placed on the original placement section 53a. At this time, the original MS is positioned in the width direction (the direction perpendicular to the paper surface) on the original placement section 53a by abutting side guides (not shown). The original MS thus set pushes up a lever member 62, which is swingably disposed above the movable original table 53b. This causes the original placement sensor 63 to detect the placement of the original MS and send a detection signal to a controller (not shown). This detection signal is then sent from the controller to the reading control section of the scanner 150 via the interface.

[0047] The document placement section 53a holds a first length sensor 57 and a second length sensor 58, which are made up of a reflective photosensor or an actuator-type sensor that detects the length of the document MS in the transport direction. These length sensors detect the length of the document MS in the transport direction.

[0048] Above the stack of original documents MS placed on movable original table 53b, there is disposed pickup roller 80, which is supported by a cam mechanism so as to be movable in the vertical direction (the directions of arrows c and d in FIG. 6). This cam mechanism is driven by a pickup motor (not shown), which can move pickup roller 80 up and down. As pickup roller 80 moves upward, movable original table 53b swings in the direction of arrow a in the figure, and pickup roller 80 comes into contact with the uppermost original document MS in the stack of original documents MS. As movable original table 53b continues to rise, table rise detection sensor 59 eventually detects that movable original table 53b has reached its upper limit. This stops the pickup motor and stops the upward movement of movable original table 53b.

[0049] An operator operates a main body operation unit, which is comprised of a numeric keypad, a display, etc., provided on the main body of image forming apparatus 100, to set the reading mode, indicating whether it is a double-sided reading mode or a single-sided reading mode, and to press a copy start key, etc. When the copy start key is pressed, a document feed signal is sent from a main body control unit (not shown) to a controller of ADF 51. Then, pickup roller 80 is rotated by forward rotation of paper feed motor 191 (described later), and feeds out document MS on movable document table 53b from movable document table 53b.

[0050] When setting the double-sided reading mode or single-sided reading mode, it is possible to collectively set double-sided or single-sided reading for all of the originals MS placed on the movable original table 53b. It is also possible to individually set the reading mode for each individual original MS, for example, by setting the first and tenth originals MS to double-sided reading mode while setting the other originals MS to single-sided reading mode.

[0051] The document MS sent out by the pickup roller 80 enters the separation and conveyance section B and is sent to a contact position with the paper feed belt 84. This paper feed belt 84 is stretched by a drive roller 82 and the like, and is moved endlessly in the clockwise direction in the figure by the rotation of the drive roller 82 accompanying the forward rotation of a paper feed motor 191. A separation roller 85, which is driven to rotate clockwise in the figure by the forward rotation of the paper feed motor 191, contacts the lower stretching surface of this paper feed belt 84. At the contact portion, the surface of the paper feed belt 84 moves in the paper feed direction. In contrast, the separation roller 85 contacts the paper feed belt 84 with a predetermined pressure, and when the separation roller 85 is in direct contact with the paper feed belt 84 or when only one document MS is sandwiched in the contact portion, it rotates along with the belt or the document MS.

[0052] However, when multiple sheets of originals MS are sandwiched in the contact portion, the accompanying rotation force becomes lower than the torque of the torque limiter, and the rollers are rotated in the clockwise direction in the figure, which is opposite to the accompanying rotation direction. As a result, the separation roller 85 applies a moving force in the opposite direction to the paper feeding to the sheets of originals MS below the top, and only the topmost sheet of originals MS is separated from the several sheets of originals (hereinafter, the operation up to this point is referred to as the paper feeding / separation operation).

[0053] The document MS, separated into a single sheet by the action of the paper feed belt 84 and separation roller 85, enters the registration section C. Then, its leading edge is detected as it passes directly below the abutment sensor 72. At this time, the pickup roller 80, which receives the driving force of the pickup motor, is still rotating, but the lowering of the movable document table 53b causes it to move away from the document MS, so that the document MS is transported only by the endless moving force of the paper feed belt 84. Then, the endless movement of the paper feed belt 84 continues for a predetermined time from the timing when the leading edge of the document MS is detected by the abutment sensor 72. As a result, the leading edge of the document MS abuts against the abutment portion between the pull-out drive roller 86 and the pull-out driven roller 87, which is driven to rotate while abutting against the pull-out drive roller 86.

[0054] The pull-out driven roller 87 serves to transport the document MS to the pair of intermediate rollers 66 downstream in the document transport direction, and is rotationally driven by the reverse rotation of the paper feed motor 191. When the paper feed motor 191 rotates reversely, the pull-out driven roller 87 and one of the rollers of the pair of intermediate rollers 66 that are in contact with each other start to rotate, and the endless movement of the paper feed belt 84 stops. At this time, the rotation of the pickup roller 80 also stops.

[0055] The document MS sent out from the pull-out driven roller 87 passes directly below the document width sensor 73. The document width sensor 73 has multiple paper detection units, each consisting of a reflective photosensor or the like, which are aligned in the document width direction (the direction perpendicular to the plane of the drawing). The widthwise size of the document MS is detected based on which paper detection unit detects the document MS. The length of the document MS in the transport direction is detected based on the timing from when the leading edge of the document MS is detected by the abutment sensor 72 to when the trailing edge of the document MS is no longer detected by the abutment sensor 72.

[0056] The leading edge of the document MS, whose widthwise size has been detected by the document width sensor 73, enters the turning section D and is sandwiched in the contact area between the rollers of the intermediate roller pair 66. The transport speed of the document MS by this intermediate roller pair 66 is set to be faster than the transport speed of the document MS in the first reading and transporting section E, which will be described later. This shortens the time it takes to send the document MS to the first reading and transporting section E.

[0057] The leading edge of the document MS being transported within the turning section D passes a position facing the reading entrance sensor 67. When the leading edge of the document MS is detected by the reading entrance sensor 67, the document transport speed by the intermediate roller pair 66 is reduced until the leading edge reaches the position of the reading entrance roller pair (pair of 89 and 90) on the downstream side in the transport direction. In addition, as the reading motor (not shown) starts to rotate, one roller of the reading entrance roller pair (89, 90), one roller of the reading exit roller pair 92, and one roller of the second reading exit roller pair 93 each start to rotate.

[0058] Within the turning section D, the document MS is reversed upside down and its transport direction is reversed while it is transported along the curved transport path between the pair of intermediate rollers 66 and the pair of reading entrance rollers (89, 90). Then, the leading edge of the document MS that has passed through the nip between the pair of reading entrance rollers (89, 90) passes directly below the registration sensor 65. Hereinafter, the operation up to this point after the paper feeding / separation operation is referred to as the pull-out operation.

[0059] When the leading edge of the document MS is detected by the registration sensor 65, the document transport speed is decelerated over a predetermined transport distance. Then, the transport motor 192 (described later) is stopped to stop the rotational drive of the pull-out drive roller 86 and the pair of intermediate rollers 66, and the reading motor (not shown) is stopped to stop the rotational drive of the pair of reading entrance rollers. This causes the transport of the document MS to be temporarily stopped at the registration position in front of the first reading transport unit E. In addition, a registration stop signal is sent to the reading control unit (not shown).

[0060] FIG. 7 is a partially enlarged view showing the main parts of FIG. 5, and FIG. 8 is a top view of a portion of the document transport path 203 of the ADF 51 according to one embodiment of the present invention. Also, FIG. 9 is a perspective view showing an example of a sound generating unit 212 according to one embodiment of the present invention, and FIG. 10 is a perspective view showing a first modified example of the sound generating unit 212 according to one embodiment of the present invention. As shown in FIGS. 7 to 10, the ADF 51 includes one or more sound generating units 212 that are provided on the document transport path 203 and have a convex or concave shape relative to the surface of the document transport path 203, and a sound collecting unit 201 that collects sound generated when the sound generating unit 212 comes into contact with a fastener attached to the document MS. Here, "collecting sound" refers to collecting sound.

[0061] As shown in Fig. 8, sound generating unit 212 is provided continuously or intermittently from one end to the other in the width direction of document transport path 203. When a document MS having a fastener such as a clip or staple attached thereto is transported through document transport path 203, sound generating unit 212 and the fastener come into contact with each other, generating an abnormal sound that is different from normal operating sounds, such as a collision sound, or a rubbing sound when the fastener passes over sound generating unit 212. Hereinafter, the sound generated by the fastener will be referred to as abnormal sound. By providing sound generating unit 212 across the entire width direction of document transport path 203, the fastener can come into contact with sound generating unit 212 and generate an abnormal sound regardless of the position of the fastener in the width direction of document transport path 203.

[0062] The ADF 51 also includes a prediction unit 202 that predicts the presence or absence of a fastener based on the sound collected by the sound collection unit 201. When the sound generation unit 212 comes into contact with a fastener, an abnormal sound is mixed with the operating sound collected by the sound collection unit 201, creating a distinctive operating sound that can be distinguished from the operating sound during normal transport, and therefore the prediction unit 202 can predict the presence or absence of a fastener based on the sound collected by the sound collection unit 201. As described above, the ADF 51 can detect a fastener attached to the document MS.

[0063] Fig. 11 is a schematic diagram showing an example of an original MS with fastener 220 attached, and Fig. 12 is a diagram illustrating the state of transport of the original MS shown in Fig. 11. Fig. 13 is a schematic diagram showing another example of an original MS with fastener 220 attached, and Fig. 14 is a diagram illustrating the state of transport of the original MS shown in Fig. 13. In the examples shown in Figs. 11 and 12, the topmost original MS is transported to the original transport path 203 with fastener 220 still attached. In such a case, if fastener 220 hits any point on the original transport path 203, the transport of the original MS will stop and a jam will occur.

[0064] 13 and 14, it is conceivable that the fastener 220 will remain in place together with the stack of originals, and the topmost original MS will be pulled out and moved forward. However, in both cases, one of the originals MS in the stack will eventually be transported together with the fastener 220. Because the fastener 220 is attached to the side in the direction of travel of the originals, if the fastener 220 comes into contact with any part of the transport path while the originals are being transported, the fastener 220 will detach from the original MS and fall onto the transport path. If the next original is transported with the fastener 220 remaining on the transport path, the next original will collide with the fallen fastener 220, causing a jam.

[0065] According to the ADF 51 of this embodiment, in cases such as those shown in Figures 11 to 14, that is, regardless of the position where the fastener passes in the document transport path 203, it is possible to predict the presence or absence of a fastener and detect a fastener attached to the document MS.

[0066] The sound generating unit 206, which has a convex shape relative to the surface of the document transport path 203, will now be described. As shown in Fig. 9, the sound generating unit 206 may have a first surface 206a extending vertically upward from the surface of the document transport path 203, and an inclined surface 206b connecting the upper end of the first surface 206a to the surface of the document transport path 203. The inclined surface 206b extends from the upper end of the first surface 206a in the opposite direction to the transport direction CD. In other words, the inclined surface 206b is provided so as to come into contact with the leading edge of the document MS being transported. The first surface 206a is a surface that extends along the width direction of the document transport path 203.

[0067] The sound generating unit 207, which has a recessed shape relative to the surface of the document transport path 203, will now be described. As shown in FIG. 10 , the sound generating unit 207 may have a first surface 207a extending vertically downward from the surface of the document transport path 203, and an inclined surface 207b connecting the lower end of the first surface 207a to the surface of the document transport path 203. The inclined surface 207b extends from the lower end of the first surface 207a in the transport direction CD. That is, the inclined surface 207b is provided so as to come into contact with the leading edge of the document being transported. The sound generating unit 207 may be a groove formed in the surface of the document transport path 203. The first surface 207a is a surface that extends along the width direction of the document transport path 203.

[0068] As described above, sound generating unit 212 preferably has first surfaces 206a, 207a extending vertically from the surface of document transport path 203, and inclined surfaces 206b, 207b extending from the ends of first surfaces 206a, 207a in the vertical direction to the surface of document transport path 203, and is provided in plurality at a distance in the transport direction CD of document MS. With this configuration, ADF 51 can increase the volume of abnormal noise and the frequency of abnormal noise generation, thereby improving the accuracy of fastener detection.

[0069] Since sound generating unit 212 has inclined surfaces 206b and 207b as described above, original document MS is transported along inclined surfaces 206b and 207b. Therefore, even if there are recesses or protrusions on original document transport path 203 due to sound generating unit 212, ADF 51 can prevent the recesses or protrusions from interfering with the transport of original document MS, thereby preventing damage to original document MS.

[0070] As shown in Fig. 8, in document transport path 203, a separation roller 85, a pull-out driven roller 87, and a pair of intermediate rollers 66 are arranged in this order from the upstream side in the transport direction CD. Note that Fig. 8 omits the curved portion between separation roller 85 and pull-out driven roller 87 on the transport path. Specifically, sound generating unit 212 may be arranged on both sides of separation roller 85, pull-out driven roller 87, and pair of intermediate rollers 66 in the width direction of document transport path 203. Furthermore, in an area in the width direction of document transport path 203 where separation roller 85, pull-out driven roller 87, and pair of intermediate rollers 66 are not arranged, sound generating unit 212 may be provided so as to extend from one end to the other end in the width direction of document transport path 203.

[0071] The sound generating unit 212 is preferably disposed upstream in the transport direction CD from the downstream end of the intermediate roller pair 66. As shown in FIG. 6, the document transport path 203 has a large curved portion downstream in the transport direction CD from the intermediate roller pair 66. If a document MS with a fastener attached enters the document transport path 203 after the intermediate roller pair 66, the fastener cannot pass through the large curved portion, causing a jam, and the document MS may become bellows, resulting in significant damage to the document MS. Furthermore, if the fastener becomes detached from the document MD in the document transport path 203 after the intermediate roller pair 66, the fastener will fall downward from the document transport path 203, making it difficult to remove.

[0072] Therefore, by positioning the sound generating unit 212 upstream in the conveying direction CD from the downstream end of the intermediate roller pair 66 in the conveying direction CD, it is possible to predict the presence or absence of a fastener before the original MS reaches the intermediate roller pair 66, thereby further preventing damage to the original MS.

[0073] The sound collection unit 201 may be a sound collection microphone. The sound collection unit 201 is attached to the paper feed cover 98 and may be provided at least above the document transport path 203. The sound collection unit 201 may be provided, for example, on the rear surface of the paper feed cover 98 of the ADF 51.

[0074] 5 to 7, the sound collection unit 201 may have a first sound collection unit 201a provided on the rear surface of the paper feed cover 98 upstream of the pickup roller 80 in the conveyance direction CD, and a second sound collection unit 201b provided on the rear surface of the paper feed cover 98 downstream of the drive roller 82 and upstream of the pull-out drive roller 86. The number of sound collection units 201 may be multiple or may be one. The position of the sound collection unit 201 is not limited to the position shown in FIGS. 5 to 7.

[0075] Fig. 15 is a perspective view showing a second modified example of sound generating unit 212 according to an embodiment of the present invention. As shown in Fig. 15, sound generating unit 208 may have notched portion 209 provided in contact surface 208a with original MS, or a rough surface portion having a surface roughness greater than the surface roughness of original transport path 203. Here, the surface roughness may be, for example, the arithmetic mean roughness (Ra).

[0076] With this configuration, in addition to the sound generated when the fastener collides with contact surface 208a, noise is also generated when the fastener rubs against contact surface 208a as it moves over the contact surface. This increases the chance of noise generation, and ADF 51 can improve the accuracy of fastener detection. In the example shown in FIG. 15, sound generating unit 208 has a convex shape relative to the surface of document transport path 203. However, the same effect can be achieved even when sound generating unit 207 has a concave shape and has a notch or a rough surface on inclined surface 207b, which is the surface that contacts document MS, as in the example shown in FIG. 10.

[0077] 16 is a perspective view showing a third modified example of sound generating unit 212 according to an embodiment of the present invention. When sound generating unit 210 has a convex shape relative to the surface of document transport path 203, as shown in FIG. 16, it may have plate member 211 including inclined surface 211a, convex portion 213 provided on the side of plate member 211, and elastic body 214 that supports plate member 211 movably in a direction perpendicular to the surface of document transport path 203. Convex portion 213 can be fixed to, for example, rib 204 (described later) provided on document transport path 203. Plate member 211 is swingable around convex portion 213 as an axis.

[0078] The sound generating unit 210, which has a convex shape relative to the surface of the document transport path 203, includes a plate 211 and an elastic body 214. When the fastener passes over the plate 211, the plate 211 is pressed down, and when the fastener passes over the plate 211, the plate 211 is bounced upward by the elastic body 214. At this time, abnormal noises are generated, such as sounds generated by the plate 211 or the elastic body 214, or sounds caused by the plate 211 coming into contact with the document MS being transported. Therefore, the ADF 51 can increase the chances of abnormal noise generation and improve the accuracy of fastener detection.

[0079] 17 is a perspective view showing a fourth modified example of the sound generating unit 212 according to an embodiment of the present invention. In addition to the configuration shown in FIG. 16, the sound generating unit 210 may also include an opposing member 231 provided above the plate material 211 and facing the plate material 211. With this configuration, when the plate material 211 is bounced upward by the elastic body 214, a portion of the inclined surface 211a of the plate material 211 that is positioned widthwise outward from the document MS collides with the opposing member 231, thereby generating a loud noise. Therefore, the ADF 51 can further improve the accuracy of fastener detection.

[0080] The opposing member 231 is fixed to a top plate 230 disposed above the document transport path 203 in an opposing manner so as to be able to swing. One end of the opposing member 231 is fixed to the top plate 230 and extends toward the plate material 211. That is, the opposing member 231 is suspended from the top plate 230, and the other end of the opposing member 231 is movable. The other end of the opposing member 231 is movable, for example, along the transport direction CD. A plurality of opposing members 231 may be provided along the width direction of the document transport path 203. The opposing member 231 may have a curved shape such that the portion on the other end side extends toward the downstream side in the transport direction CD. The other end of the opposing member 231 abuts against the plate material 211. A plurality of elastic bodies 214 may be provided.

[0081] The material constituting the opposing member may be metal. By using a metal material for the opposing member, a portion of the inclined surface 211a of the plate member 211 that is positioned widthwise outward of the document MS can collide with the opposing member, generating a sound having a frequency different from the operating sound. Therefore, the ADF 51 can further improve the detection accuracy of the fastener.

[0082] Fig. 18 is a top view of a portion of a first modified example of the document transport path 203 according to one embodiment of the present invention, Fig. 19 is a view of Fig. 18 as seen from the upstream side in the transport direction CD, and Fig. 20 is a side view of Fig. 18. As shown in Figs. 18 and 20, the ADF 51 may include ribs 204 that are provided on the document transport path 203 and extend along the transport direction CD of the document MS. The ribs 204 have the function of reducing frictional force when they come into contact with the document MS during transport. A plurality of ribs 204 may be provided spaced apart from each other in the width direction of the document transport path 203.

[0083] FIG. 21 is a perspective view showing a fifth modified example of sound generating unit 212 according to an embodiment of the present invention. As shown in FIG. 21, one or more sound generating units 205 having a concave shape relative to the surface of document transport path 203 may be provided on the upper surface of rib 204. If ADF 51 includes rib 204, it would be difficult to provide convex sound generating unit 212 from one end to the other in the width direction of document transport path 203. By providing sound generating unit 205 having a concave shape on the upper surface of rib 204, it is possible to generate an abnormal sound when a fastener passes over rib 204. Therefore, ADF 51 can detect the fastener.

[0084] As shown in FIG. 21 , the sound generating unit 205 may have a first surface 205a extending vertically downward from the upper surface of the rib 204, and an inclined surface 205b connecting the lower end of the first surface 205a and the upper surface of the rib 204. The inclined surface 205b extends from the lower end of the first surface 205a in the conveying direction CD. That is, the inclined surface 205b is provided so as to come into contact with the leading edge of the document MS being conveyed. The sound generating unit 205 may be a groove formed in the upper surface of the rib 204. The first surface 205a is a surface that extends along the width direction of the document conveying path 203. The sound generating unit 205 may be provided on each of the multiple ribs 204, and may be arranged on the same straight line in the width direction of the document conveying path 203.

[0085] Fig. 22 is a top view of a portion of a second modified example of document transport path 203 according to an embodiment of the present invention, and Fig. 23 is an enlarged perspective view of a portion of Fig. 22. When a plurality of ribs 204 are provided spaced apart from each other in the width direction of document transport path 203, sound generating units 212 may have a convex shape with respect to the surface of document transport path 203, as shown in Figs. 22 and 23, and a plurality of sound generating units 212 may be provided so as to fill the spaces between ribs 204 in the width direction of document transport path 203. In addition, the height of sound generating units 212 relative to the surface of document transport path 203 is preferably lower than the height of ribs 204 relative to the surface of document transport path 203.

[0086] If the height of sound generating unit 212 relative to the surface of document transport path 203 is equal to or greater than the height of ribs 204 relative to the surface of document transport path 203, document MS will be transported while in contact with sound generating unit 212, which may result in damage to document MS. By making the height of sound generating unit 212 relative to the surface of document transport path 203 lower than the height of ribs 204 relative to the surface of document transport path 203, the probability that document MS will come into contact with sound generating unit 212 can be reduced, thereby preventing damage to document MS. Furthermore, by reducing the probability that document MS will come into contact with sound generating unit 212, it becomes easier to detect abnormal sounds generated when a fastener comes into contact with sound generating unit 212, and therefore ADF 51 can further improve the accuracy of fastener detection.

[0087] The difference between the height of sound generating unit 212 relative to the surface of document transport path 203 and the height of rib 204 relative to the surface of document transport path 203 can be set to, for example, equal to or less than the thickness of the fastener.

[0088] 22 and 23, the top surface of the rib 204 is flat, but this is not limiting, and the sound generating portion 205 shown in Fig. 21 may be provided on the top surface of the rib 204. This makes it possible to increase the amount of abnormal noise generated when the fastener comes into contact with the sound generating portion 212.

[0089] FIG. 24 is a top view of a portion of the document transport path 203 of another example of the ADF 51 according to an embodiment of the present invention. As shown in FIG. 24, multiple sound generating units 212 may be arranged at different intervals in the transport direction CD of the document MS. With this configuration, when a fastener passes over the sound generating units 212, sounds, particularly collision sounds, can be generated irregularly, and sounds with a specific rhythm can be generated. Therefore, the prediction unit 202 can predict the presence or absence of a fastener based on the sounds with a specific rhythm, and the ADF 51 can further improve the accuracy of fastener detection.

[0090] Examples of materials that form the surface of sound generating unit 212 include resin and metal. The material that forms the surface of sound generating unit 212 is preferably metal. This increases the difference between the frequency of abnormal noise generated by contact between the fastener and sound generating unit 212 and the frequency of normal operating noise when the fastener is made of metal, allowing ADF 51 to further improve the accuracy of fastener detection.

[0091] 25 is a block diagram showing part of the electrical circuit of image forming apparatus 100 according to one embodiment of the present invention. Main body control unit 901 of image forming unit 1, read control unit 903 of scanner 150, and controller 904 of ADF 51 are each composed of a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), etc. Main body control unit 901 and read control unit 903, read control unit 903 and controller 904, and controller 904 and main body control unit 901 are each connected to one another and are capable of communicating with one another.

[0092] The controller 904 is connected to the registration sensor 65, the document set sensor 63, the paper discharge sensor 61, the abutment sensor 72, the document width sensor 73, the reading entrance sensor 67, the length sensors 57 and 58, etc. Also connected to the controller 904 are the paper feed motor 191, the transport motor 192, the pull-out clutch 193, the paper discharge clutch 194, and the prediction unit 202. The prediction unit 202 is connected to the sound collection unit 201.

[0093] A transport motor 192 connected to a controller 904 is a rotational drive source for the pull-out drive roller 86 and the pair of paper discharge rollers 94 in the ADF 51. A pull-out clutch 193 connected to the controller 904 connects or disconnects the rotational drive force of the transport motor 192 to or from the pull-out drive roller 86. A paper discharge clutch 194 connects or disconnects the rotational drive force of the transport motor 192 to or from the pair of paper discharge rollers 94, which are the feed-out transport means.

[0094] Upon receiving the registration stop signal from the controller 904, the reading control unit 903 transmits a reading start signal, which is a paper feed permission signal, to the controller 904. The controller 904 then resumes rotation of the transport motor 192 and the reading motor. Then, at the timing when the leading edge of the original MS, calculated based on the pulse count of the reading motor, reaches the reading position by the first-side fixed reading unit 151, the controller 904 transmits a gate signal indicating the sub-scanning direction effective image area of ​​the first side of the original MS to the reading control unit 903. This transmission continues until the trailing edge of the original MS leaves the reading position by the first-side fixed reading unit 151, and the first side of the original MS is read by the first-side fixed reading unit 151.

[0095] After passing through the first reading conveyance unit E, the original MS passes through a pair of reading exit rollers 92 (described later), and then its leading edge is detected by the paper discharge sensor 61. When the single-sided reading mode is set, there is no need to read the second side of the original MS by the second fixed reading unit 95 (described later). Therefore, when the leading edge of the original MS is detected by the paper discharge sensor 61, the driving force of the conveyance motor is connected to the pair of paper discharge rollers 94 by the paper discharge clutch 194. Then, based on the paper discharge motor pulse count after the leading edge of the original MS is detected by the paper discharge sensor 61, the timing at which the trailing edge of the original MS will leave the nip of the pair of paper discharge rollers 94 is calculated. Then, based on the result of this calculation, the operation of the paper discharge clutch 194 is stopped.

[0096] On the other hand, when the double-sided reading mode is set, the timing from when the leading edge of the original MS is detected by the paper discharge sensor 61 until the original reaches the second fixed reading unit 95 is calculated based on the pulse count of the reading motor. Then, at that timing, the controller transmits a gate signal indicating the effective image area in the sub-scanning direction on the second side of the original MS to the reading control unit. This transmission continues until the trailing edge of the original MS leaves the reading position of the second fixed reading unit 95, and the second side of the original MS is read by the second fixed reading unit 95.

[0097] The second fixed reading unit 95 is composed of a contact image sensor (CIS), and its reading surface is coated to prevent vertical reading streaks caused by glue-like foreign matter adhering to the document MS adhering to the reading surface. A second reading roller 96 is disposed opposite the second fixed reading unit 95 as a document support means for supporting the document MS from the non-reading side. This second reading roller 96 prevents the document MS from floating at the reading position of the second fixed reading unit 95, and also functions as a reference white area for acquiring shading data for the second fixed reading unit 95.

[0098] The prediction unit 202 can predict the presence or absence of a fastener using parameters acquired in advance through machine learning. Machine learning will be described later.

[0099] Fig. 26 is a flowchart showing fastener determination processing performed by controller 904 according to one embodiment of the present invention. Controller 904 performs operation processing to separate and feed each original MS one by one from the stack of originals MS set on original placement unit 53a, and performs processing for each original MS according to the flow shown in Fig. 26. Note that in order to increase reading throughput, the originals MS are continuously fed while leaving sufficient space between each original MS so that they do not overlap, and therefore, multiple originals MS are simultaneously present at intervals on original transport path 203. Therefore, the flow shown in Fig. 26 is executed in parallel for each original MS, leaving sufficient space between each original MS.

[0100] When a read instruction is sent from the main body control unit 901 to the controller 904, the controller 904 starts a document transport operation (step S1), as shown in FIG. 26, and at the same time, starts collecting operation sounds using the sound collection unit 201 (step S2). Specifically, in step S1, the controller 904 starts driving the pickup roller 80. Then, the document MS enters the document transport path 203 and passes over the sound generation unit 212. If a fastener is attached to the document MS, an abnormal sound is generated. The prediction unit 202 acquires the collected operation sound data from the sound collection unit 201 and starts a process of predicting a transport abnormality, i.e., a process of predicting the presence or absence of a fastener, based on the operation sound data (step S3).

[0101] In step S3, a process of predicting the presence or absence of a fastener is executed at regular intervals. In step S3, the prediction unit 202 uses "parameters acquired in advance through machine learning" to determine whether the transport of the original MS is normal or abnormal (whether a fastener is present or absent).

[0102] The "parameters acquired in advance through machine learning" can be generated as follows: The sounds of passing a document MS without a fastener and the sounds of passing a document MS with a fastener are recorded under various conditions, in other words, with error factors added. These sounds are then labeled as "with fastener" or "without fastener" and subjected to machine learning. The generated parameters correspond to the "learning model" in the explanation of machine learning below.

[0103] Here we will provide an overview of machine learning. Machine learning is a method of analyzing data in which a computer (machine) "automatically learns" from the data and discovers the rules and patterns behind the data. The rules and patterns that result from this learning are called a "learning model." This learning model, obtained through prior learning, can be used to make predictions and decisions.

[0104] Examples of machine learning include the Mahalanobis Taguchi (MT) method and support vector machines, but the MT method will be used for explanation here. The sound signals collected by the sound collection unit 201 are stored in the internal RAM of the controller 904. The stored sound signals are multiplied by a window function while shifting it (framing process), and then a short-time Fourier transform (STFT) is performed by Fourier transforming the result, and the time sequence of the power spectrum of the sound signal is calculated in real time. Furthermore, a characterization process is sequentially performed on the time sequence of the calculated power spectrum, and sound features are calculated, which are also stored in the RAM. Here, for example, the time integration of power in a predetermined frequency band, the spectral flux between consecutive frames, etc. can be used as the characterization process.

[0105] Next, the accumulated sound features are used as input to predict conveyance abnormalities. Here, we will explain a method that uses Mahalanobis distance with the MT method. In fields such as quality engineering, MT systems are known for performing predictions, diagnoses, and analyses using multidimensional information data (see reference: Genichi Taguchi, "Mathematics of Quality Engineering" (Japanese Standards Association, 1999)). The MT system is a general term for methods of analyzing multidimensional information data, such as the MT method, MTA method, TS method, T method (1), T method (2), RT method, and mispressure method. Here, the MT method is a method that uses Mahalanobis distance, and is a simple and relatively accurate method that takes into account correlation between items.

[0106] The inverse matrix R-1 of the correlation matrix of the unit space data set used when calculating the Mahalanobis distance is stored in the ROM of the controller 904. A normal original MS is read under various error factor conditions, a unit space data set (reference data set) is created based on the feature quantities obtained from the sound signal, and the inverse matrix R-1 of the correlation matrix is ​​calculated in advance and stored in the ROM of the controller 904. The calculated unit space data set corresponds to the "learning model."

[0107] If the Mahalanobis distance is equal to or less than a predetermined threshold Th, it is determined to be normal (no fastener), and if it is greater than the threshold Th, it is determined to be abnormal (fastener present). The threshold Th is set to a value that can be easily determined to be normal for a unit space data set (reference data set) created under various error factor conditions. Therefore, a threshold Th that is less likely to generate false positives is set, while allowing a certain degree of false negatives. Using the above machine learning, a prediction process for the presence or absence of a fastener is performed in step S3.

[0108] Prediction unit 202 determines whether there is a transport abnormality (whether there is a fastener), and if it determines that there is a transport abnormality (there is a fastener) (step S4: Yes), it ends the transport abnormality prediction process (step S5). At this time, sound collection by sound collection unit 201 also ends. After step S5, it stops driving paper feed motor 191 and raises pickup roller 80 to stop the document transport operation (step S6). At this point, the reading operation of document MS has not yet been performed. After step S6, controller 904 transmits a result indicating that there is a transport abnormality to main body control unit 901 (step S7).

[0109] The main body control unit 901 completes the read instruction when it receives a result indicating that a transport abnormality has occurred from the controller 904. The main body control unit 901 also notifies the user of the transport status by displaying a message such as "A transport abnormality in the document has been detected. Please check the document" on the display unit of the main body operation unit 902 along with sounding an alarm indicating a transport abnormality.

[0110] On the other hand, if the prediction unit 202 determines that there is no transport abnormality (no fastener) (step S4: No), the document transport operation continues (step S8). After step S8, it is determined whether the document MS has passed a certain distance from the abutment sensor 72 (step S9). Here, the certain distance from the sensor 72 may be, for example, the distance from the sensor 72 to the pair of intermediate rollers 66. If it is determined that the document MS has passed a certain distance from the abutment sensor 72 (step S9: Yes), the transport abnormality prediction process ends (step 10). At this time, sound collection by the sound collection unit 201 also ends.

[0111] After step 10, the document transport operation continues (step 11), and processing for reading and transporting the document MS is started (step 12). Note that between steps 11 and 12, a process for detecting transport abnormalities may be performed using another conventionally provided sensor.

[0112] After step S12, the process for reading and transporting the document MS is completed (step S13). After step S13, the controller 904 transmits a result indicating that there is no transport abnormality to the main body control unit 901 (step S7). When the main body control unit 901 receives the result indicating that there is no transport abnormality from the controller 904, it completes the reading instruction.

[0113] If it is determined that the document MS has not passed a certain distance from the abutment sensor 72 (step S9: No), the process returns to step S4, and the prediction unit 202 again determines whether or not there is a transport abnormality (whether or not there is a fastener).

[0114] The image forming apparatus 100 of this embodiment includes an automatic document feeder 51 and an image forming unit 1. With this configuration, the image forming apparatus 100 includes the automatic document feeder 51, and therefore can detect fasteners attached to the document MS.

[0115] (Aspects of the present invention) The present invention includes the following aspects. <Aspect 1> a document placement section for placing a document; a document transport section that transports the document placed on the document placement section along a document transport path; one or more sound generating units that are provided on the document transport path and have a convex or concave shape relative to the surface of the document transport path; a sound collection unit that collects the sound generated when the sound generation unit comes into contact with a fastener attached to the document; a prediction unit that predicts the presence or absence of the fastener based on the sound collected by the sound collection unit, The sound generating unit is an automatic document feeder that is provided continuously or intermittently across the document feed path from one end to the other end in the width direction. <Aspect 2> In the automatic document feeder described in aspect 1, the sound generating unit has a first surface extending vertically from the surface of the document feed path and an inclined surface extending from the end of the first surface in the vertical direction to the surface of the document feed path, and is provided in multiple units spaced apart in the document feed direction. <Aspect 3> a rib provided on the document transport path and extending along the document transport direction; In the automatic document feeder according to aspect 1, one or more of the sound generating sections, each having a concave shape relative to the surface of the document feed path, are provided on an upper surface of the rib. <Aspect 4> The automatic document feeder according to aspect 1 has a sound generating unit having a convex shape, a plate material including an inclined surface, and an elastic body that supports the plate material so that it can move in a direction perpendicular to the surface of the document feed path. <Aspect 5> In the automatic document feeder of any one of aspects 1 to 4, the sound generating unit has a notch provided on the surface that comes into contact with the document, or a rough surface portion having a surface roughness greater than the surface roughness of the document feed path. <Aspect 6> a rib provided on the document transport path and extending along the document transport direction; a plurality of the ribs are provided spaced apart from each other in the width direction of the document transport path; the sound generating unit has a convex shape relative to the surface of the document transport path, and a plurality of sound generating units are provided so as to fill the spaces between the ribs in the width direction of the document transport path; In the automatic document feeder according to aspect 1 or 2, the height of the sound generating unit relative to the surface of the document feed path is lower than the height of the rib relative to the surface of the document feed path. <Aspect 7> The automatic document feeder according to aspect 4 further includes an opposing member provided above the plate member so as to face the plate member. <Aspect 8> In the automatic document feeder according to aspect 2, the plurality of sound generating units are arranged at different intervals in the document feed direction. <Aspect 9> An automatic document feeder according to any one of aspects 1 to 8; The image forming apparatus is provided with an image forming unit that forms an image.

[0116] Although the embodiments have been described above, they are presented as examples and the present invention is not limited to the above embodiments. The above embodiments can be implemented in various other forms, and various combinations, omissions, substitutions, modifications, etc. can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the inventions and their equivalents as set forth in the claims. [Explanation of symbols]

[0117] 1 Image forming unit 201 Sound collection section 202 Prediction Department 203 Document transport path 204 Ribs 209 Notch 211 Board material 214 Elastic Body 212 Sound generating unit 51 Automatic document feeder 53a Document placement section 100 Image forming device MS manuscript [Prior art documents] [Patent documents]

[0118] [Patent Document 1] Japanese Patent Application Laid-Open No. 2019-137549

Claims

1. a document placement section for placing a document; a document transport section that transports the document placed on the document placement section along a document transport path; one or more sound generating units that are provided on the document transport path and have a convex or concave shape relative to the surface of the document transport path; a sound collection unit that collects the sound generated when the sound generation unit comes into contact with a fastener attached to the document; a prediction unit that predicts the presence or absence of the fastener based on the sound collected by the sound collection unit, The sound generating unit is provided continuously or intermittently across the width of the document transport path from one end to the other end of the document transport path.

2. The automatic document feeder of claim 1, wherein the sound generating unit has a first surface extending vertically from the surface of the document transport path and an inclined surface extending from the end of the first surface in the vertical direction to the surface of the document transport path, and is provided in multiple units spaced apart in the document transport direction.

3. a rib provided on the document transport path and extending along the document transport direction; 2. The automatic document feeder according to claim 1, wherein one or more of the sound generating portions are provided on the upper surface of the rib, the sound generating portions having a concave shape relative to the surface of the document feed path.

4. 2. The automatic document feeder according to claim 1, wherein the convex sound generating portion comprises a plate member including an inclined surface, and an elastic body that supports the plate member so that the plate member can move in a direction perpendicular to the surface of the document feed path.

5. 2. The automatic document feeder according to claim 1, wherein the sound generating unit has a notch provided on a surface that comes into contact with the document, or a rough surface portion having a surface roughness greater than a surface roughness of the document feed path.

6. a rib provided on the document transport path and extending along the document transport direction; a plurality of the ribs are provided spaced apart from each other in the width direction of the document transport path; the sound generating unit has a convex shape relative to the surface of the document transport path, and a plurality of sound generating units are provided so as to fill the spaces between the ribs in the width direction of the document transport path; 2. The automatic document feeder according to claim 1, wherein the height of the sound generating unit relative to the surface of the document feed path is lower than the height of the rib relative to the surface of the document feed path.

7. 5. The automatic document feeder according to claim 4, further comprising an opposing member provided above the plate member so as to face the plate member.

8. 3. The automatic document feeder according to claim 2, wherein the plurality of sound generating units are arranged at different intervals in the document feed direction.

9. An automatic document feeder according to any one of claims 1 to 8; and an image forming unit that forms an image.

Images