JP7709675B2 - SHEET CONVEYING DEVICE, AUTOMATIC DOCUMENT CONVEYING DEVICE, IMAGE READING DEVICE, AND IMAGE FORMING DEVICE - Google Patents

Description

The present invention relates to a sheet transport device, an automatic document transport device, an image reading device, and an image forming device.

Conventionally, a sheet transport device is known that includes a sheet placement section on which a sheet is placed, a sheet transport means for transporting the sheet placed on the sheet placement section, and a metal detection means for detecting metal attached to the sheet.

Patent document 1 describes a sheet transport device that includes a metal detection means having an actuator that is supported so as to be able to swing and has a magnetic member fixed to its tip, and a sensor that detects the swinging of the actuator. When a metal object such as a paperclip or staple is attached to the sheet, the actuator swings due to the magnetic force between the metal object of the sheet and the magnetic member, and the sensor detects the swinging, thereby detecting that a metal object is attached to the sheet.

However, the configuration of the metal detection means described in Patent Document 1 had the problem of increasing the size and cost of the device.

In order to solve the above-mentioned problems, the present invention provides a sheet transporting device comprising a sheet placing section on which a sheet is placed, a sheet transporting means for transporting the sheet placed on the sheet placing section, and a metal detection means for detecting metal attached to the sheet , wherein the sheet transporting means has a feeding member for feeding the sheet placed on the sheet placing section, and the metal detection means comprises a magnetic force generating means, a contact member with which the metal attached to the sheet attracted by the magnetic force generating means comes into contact, and a sound collecting means capable of collecting sound when the contact member and the metal come into contact, and the metal is detected based on the sound collected by the sound collecting means, and the contact member and the magnetic force generating means are provided on a holding member that holds the feeding member .

The present invention makes it possible to prevent the device from becoming too large or the cost of the device from increasing.

FIG. 1 is a schematic diagram showing the configuration of a copying machine according to an embodiment. FIG. 2 is a partially enlarged view showing an internal configuration of an image forming unit in the copying machine. FIG. 2 is a partial enlarged view showing a part of a tandem portion including four process units in the image forming portion. FIG. 2 is a perspective view showing a scanner and an ADF of the copying machine. FIG. 2 is an enlarged view showing the main configuration of the ADF together with the upper part of the scanner. FIG. 2 is a block diagram showing a part of the electrical circuitry of the ADF and the scanner. FIG. 4 is an explanatory diagram regarding the arrangement of a sound collecting microphone, an electromagnet, and a contact member of the ADF. 5A and 5B are diagrams for explaining detection of a metal piece attached to a document. 4 is a flowchart showing a metal piece discrimination process executed by the ADF controller. FIG. 4 is a schematic diagram showing a configuration of a first modified example of the ADF. 10A to 10C are diagrams illustrating detection of a metal piece attached to a document in the first modified example. FIG. 13 is a schematic diagram showing the configuration of a second modified example of the ADF. 10A and 10B are diagrams for explaining detection of a metal piece attached to a document in Modification 2. FIG. 13 is a schematic diagram showing the configuration of a third modified example of the ADF. 13A and 13B are diagrams illustrating an example in which the iron core of an electromagnet is used as a contact member. FIG. 13 is a diagram showing an example of a configuration for controlling ON/OFF of a magnetic force acting on a document using a permanent magnet.

Hereinafter, an embodiment in which the present invention is applied to an electrophotographic copying machine (hereinafter, simply referred to as a copying machine) will be described.
First, the basic configuration of the copying machine according to the embodiment will be described. Fig. 1 is a schematic diagram showing the copying machine according to the embodiment. This copying machine includes an image forming unit 1, a blank paper supplying device 40, and a document reading device 50. The document reading device 50 includes a scanner 150 fixed on the image forming unit 1, and an ADF 51, which is a document transport device, supported by the scanner 150.

The blank paper supply device 40 has two paper feed cassettes 42 as sheet placement sections arranged in multiple stages in a paper bank 41. The blank paper supply device 40 also has a feed roller 43 as a feed member that feeds transfer paper as a sheet from the paper feed cassette, and a separation roller 45 as a separation member that separates the fed transfer paper and supplies it to a paper feed path 44. It also has a number of transport rollers 47 that transport the transfer paper to the paper feed path 37 of the image forming unit 1. The blank paper supply device 40 feeds the transfer paper in the paper feed cassette into the paper feed path 37 in the image forming unit 1.

Figure 2 is a partially enlarged diagram showing the internal structure of the image forming unit. The image forming unit 1 as an image forming means includes an optical writing device 2, four process units 3K, Y, M, and C for forming K, Y, M, and C color toner images, and a transfer unit 24. The image forming unit 1 also includes 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. The optical writing device 2 drives a light source such as a laser diode or LED arranged in the device to irradiate laser light L toward the four drum-shaped photoconductors 4K, Y, M, and C. This irradiation forms an electrostatic latent image on the surface of the photoconductors 4K, Y, M, and C, and the latent image is developed into a toner image through a predetermined development process. The subscripts K, Y, M, and C added after the reference numbers indicate that the specifications are for black, yellow, magenta, and cyan.

Each of the process units 3K, Y, M, and C supports the photoconductor and various devices arranged around it as a single unit on a common support, and is detachable from the main body of the image forming unit 1. Taking the black process unit 3K as an example, in addition to the photoconductor 4K, it has a developing device 6K for developing the electrostatic latent image formed on the surface of the photoconductor 4K into a black toner image. It also has a drum cleaning device 15 for cleaning the residual toner adhering to the surface of the photoconductor 4K after passing through the K primary transfer nip, which will be described later. This copier has a so-called tandem type configuration in which the four process units 3K, Y, M, and C are arranged opposite to the intermediate transfer belt 25, which will be described later, along the endless movement direction of the belt.

Figure 3 is a partially enlarged view showing a part of a tandem section consisting of four process units 3K, Y, M, and C. Note that the four process units 3K, Y, M, and C have almost the same configuration except for the color of toner they use, so the subscripts K, Y, M, and C attached to each reference number are omitted in this figure. As shown in this figure, the process unit 3 has a charging device 5, a developing device 6, a drum cleaning device 15, a static elimination lamp 22, etc. around the photoconductor 4.

The photoreceptor 4 is a drum-shaped tube made of aluminum or other material, with a photosensitive layer formed by applying an organic photosensitive material. However, an endless belt-shaped one may also be used.

The developing device 6 develops the latent image using a two-component developer containing a magnetic carrier and a non-magnetic toner. The developing device 6 has an agitation 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.

The agitation section 7 is located at a lower position than the development 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 development case 9.

The developing section 11 has a developing sleeve 12 that faces the photoconductor 4 through the opening of the developing case 9, a magnet roller 13 that is non-rotatably installed inside the developing sleeve, and a doctor blade 14 that brings the tip of the developing sleeve 12 close to it. The developing sleeve 12 is a non-magnetic, rotatable cylinder. The magnet roller 13 has multiple magnetic poles that are arranged in sequence from the position facing the doctor blade 14 toward the rotation direction of the sleeve. Each of these magnetic poles exerts a magnetic force on the two-component developer on the sleeve at a predetermined position in the rotation direction. As a result, the two-component developer sent from the stirring section 7 is attracted to the surface of the developing sleeve 12 and carried thereon, and a magnetic brush is formed on the sleeve surface along the magnetic lines.

The magnetic brush is regulated to an appropriate layer thickness when it passes the position facing the doctor blade 14 as the developing sleeve 12 rotates, and then is transported to the development area facing the photoconductor 4. Then, the toner of the magnetic brush is transferred onto the electrostatic latent image due to the potential difference between the developing bias applied to the developing sleeve 12 and the electrostatic latent image on the photoconductor 4, contributing to development. Furthermore, the magnetic brush returns to the developing section 11 again as the developing sleeve 12 rotates, and after being detached from the sleeve surface due to the influence of the repulsive magnetic field formed between the magnetic poles of the magnet roller 13, it is returned to the stirring section 7. In the stirring section 7, an appropriate amount of toner is replenished to the two-component developer based on the detection result by the toner concentration sensor 10. Note that instead of using a two-component developer, the developing device 6 may be one that uses a one-component developer that does not contain a magnetic carrier.

The drum cleaning device 15 presses a cleaning blade 16 made of polyurethane rubber against the photoreceptor 4, but other methods may be used. To improve cleaning performance, the drum cleaning device 15 is provided with a contact-conductive fur brush 17 whose outer circumferential surface contacts the photoreceptor 4 and which is rotatable in the direction of the arrow in the figure. This fur brush 17 also serves to scrape the lubricant from the solid lubricant, turning it into a fine powder and applying it to the surface of the photoreceptor 4.

A metal electric field roller 18 that applies a bias to the fur brush 17 is rotatable in the direction of the arrow in the figure, and the tip of a scraper 19 is pressed against it. The toner adhering to the fur brush 17 is transferred to the electric field roller 18, which is rotated in the counter direction relative to the fur brush 17 and to which a bias is applied. The toner is then scraped off from the electric field roller 18 by the scraper 19 and falls onto the recovery screw 20. The recovery screw 20 transports the recovered toner toward the end of the drum cleaning device 15 in the direction perpendicular to the plane of the drawing, and hands it over to an external recycling transport device 21. The recycling transport device 21 sends the toner to the developing device 6 for recycling.

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.

In FIG. 2 shown above, K, Y, M, and C toner images are formed on the photoconductors 4K, Y, M, and C of the four process units 3K, Y, M, and C by the process described above.

A transfer unit 24 is disposed below the four process units 3K, Y, M, and C. This transfer unit 24 moves an intermediate transfer belt 25, stretched by multiple rollers, endlessly in the clockwise direction in the figure while abutting against the photoconductors 4K, Y, M, and C. This forms a primary transfer nip for K, Y, M, and C where the photoconductors 4K, Y, M, and C abut against the intermediate transfer belt 25. In the vicinity of the primary transfer nip for K, Y, M, and C, primary transfer rollers 26K, Y, M, and C disposed on the inside of the belt loop press the intermediate transfer belt 25 against 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. As a result, a primary transfer electric field is formed in the primary transfer nips for K, Y, M, and C, which electrostatically moves the toner images on the photoconductors 4K, Y, M, and C toward the intermediate transfer belt 25. As the intermediate transfer belt 25 moves endlessly in the clockwise direction in the figure, the toner images are sequentially superimposed and primary transferred to the front surface of the intermediate transfer belt 25 at each primary transfer nip. This primary transfer of superimposed images forms a four-color superimposed toner image (hereinafter referred to as a four-color toner image) on the front surface of the intermediate transfer belt 25.

Below the transfer unit 24 in the figure, there is a paper transport unit 28 that stretches an endless paper transport belt 29 between a drive roller 30 and a secondary transfer roller 31 and moves it endlessly. The intermediate transfer belt 25 and the paper transport belt 29 are sandwiched between the secondary transfer roller 31 itself and the 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. A secondary transfer bias is applied to the secondary transfer roller 31 by a power source. 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.

A pair of registration rollers 33 is disposed to the right of this secondary transfer nip in the figure, and the transfer paper sandwiched between the rollers is sent to the secondary transfer nip at a timing that allows it to be synchronized with the four-color toner image on the intermediate transfer belt 25. In the secondary transfer nip, the four-color toner image on the intermediate transfer belt 25 is secondarily transferred en bloc to the transfer paper due to the influence of the secondary transfer electric field and nip pressure, and becomes a full-color image combined with the white color of the transfer paper. The transfer paper that has passed through the secondary transfer nip is separated from the intermediate transfer belt 25 and, while being held on the front surface of the paper transport belt 29, is transported to the fixing device 34 as it moves endlessly.

After passing through the secondary transfer nip, residual toner that was not transferred to the transfer paper 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.

The transfer paper is conveyed to the fixing device 34, where the full-color image is fixed by pressure and heat, and then sent from the fixing device 34 to a pair of paper discharge rollers 35, and then discharged outside the machine.

In FIG. 1, a switchback device 36 is provided below the paper transport unit 28 and the fixing device 34. As a result, the transfer paper, which has completed image fixing processing on one side, has its path switched by a switching claw to the transfer paper reversing device side, where it is reversed and enters the secondary transfer nip again. Then, the other side is subjected to secondary image transfer processing and fixing processing, and the paper is discharged onto the paper discharge tray.

The scanner 150 fixed on the image forming unit 1 has a fixed first-side reading unit 151 as a first-side reading means and a movable reading unit 152 as a first-side reading means.

The moving reading unit 152, which serves as the first surface reading means, is disposed directly below the second contact glass fixed to the top wall of the casing of the scanner 150 so as to come into contact with the original MS, and can move an optical system consisting of a light source, a reflecting mirror, etc., in the left-right direction in the figure. As the moving reading unit 152 moves the optical system from the left to the right in the figure, the light emitted from the light source is reflected by the original placed on the second contact glass, and then passes through multiple reflecting mirrors before being received by the image reading sensor 153 fixed to the scanner body.

The fixed first-side reading unit 151, which serves as the first-side reading means, is disposed directly below a first contact glass that is fixed to the upper wall of the casing of the scanner 150 so as to come into contact with the original MS. Then, when the original MS transported by the ADF 51 (described later) passes over the first contact glass, light emitted from a light source is sequentially reflected by the original surface, passes through multiple reflecting mirrors, and is received by an 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, etc.

The scanner 150 also has a contact type image sensor that reads the second side of the document MS. This contact type image sensor will be described later.

The ADF 51 arranged on the scanner 150 holds, in the main body cover 52, a document placement table 53 for placing the document MS before reading, a transport unit for transporting the document MS, a document stack table 55 for stacking the document MS after reading, and the like. As shown in FIG. 4, the ADF 51 is supported by a hinge 159 fixed to the scanner 150 so as to be able to swing up and down. The ADF 51 moves like an opening and closing door by swinging, and when opened, the first contact glass 154 and the second contact glass 155 on the top surface of the scanner 150 are exposed. In the case of a single-sided bound document such as a book bound at one corner of a document stack, the documents cannot be separated one by one, so that the ADF 51 cannot transport the document. Therefore, in the case of a single-sided bound document, the ADF 51 is opened as shown in FIG. 4, and then 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 51 is closed. The image of the page is then read by the moving reading unit 152 of the scanner 150 shown in Figure 1.

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 documents can be read sequentially by the first-side fixed reading unit 151 in the scanner 150 or the contact-type image sensor in the ADF 51. In this case, after placing the document stack on the document placement table 53, the user presses the copy start button. The ADF 51 then feeds the documents MS of the document stack placed on the document placement table 53 from the top in order, and transports them toward the document stack table 55 while inverting them. During this transport process, the documents MS are inverted and immediately pass directly above the first-side fixed reading unit 151 of the scanner 150. At this time, the image on the first side of the documents MS is read by the first-side fixed reading unit 151 of the scanner 150.

Figure 5 is an enlarged diagram showing the main components of the ADF 51 together with the top of the scanner 150. Also, Figure 6 is a block diagram showing part of the electrical circuitry of the ADF 51 and the scanner 150. The ADF 51 includes a document setting section A, a separation transport section B, a registration section C, a turn section D, a first reading transport section E, a second reading transport section F, a paper discharge section G, a stack section H, etc.

As shown in FIG. 6, the ADF 51 has a controller 904 consisting of an ASIC (Application Specific Integrated Circuit) or the like, which can control various devices and sensors. 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, and the like are connected to this controller 904. Also connected are the paper feed motor 191, the transport motor 192, the pickup motor 193, the paper discharge clutch 194, and the like. Also connected are the sound collection microphone 803 as a sound collection means, and the electromagnet 801 as a magnetic force generation means, and the like.

The electromagnet 801 attracts metal pieces, such as staples or paperclips, attached to the document to a contact member 802 (see FIG. 7), which will be described later, and brings them into contact with the contact member 802. The sound-collecting microphone 803 captures the sound when metal pieces, such as staples or paperclips, attached to the document hit the contact member 802.

The scanner 150 has a reading control unit 903 consisting of a CPU (Central Processing Unit), RAM (Random Access Memory), etc. This allows it to control various devices and sensors inside the scanner 150. The reading control unit 903 is also connected to a controller 904 of the ADF 51 via an I/F, and the reading control unit 903 can also indirectly control various devices and sensors inside the ADF 51 via the controller 904.

In FIG. 5, the document set section A has a document placement table 53 on which a stack of documents MS as sheets is set. The separation and transport section B separates and feeds the documents MS one by one from the set stack of documents MS. The registration section C temporarily hits the fed documents MS to align them and then sends them out. The turn section D has a curved transport section that curves in a C shape, and turns the document MS upside down while folding it back inside the curved transport section. The first reading and transport section E transports the document MS on the first contact glass 154, while having the first surface fixed reading section 151 disposed inside the scanner below the first contact glass 154 read the first surface of the document MS. The second reading and transport section F transports the document MS under the contact image sensor 95, while having the contact image sensor 95 read the second surface of the document MS. The paper discharge section G discharges the document MS, whose images have been read from both sides, toward the stack section H. The stack section H stacks the document MS on the document stack table 55.

The document MS is set with its leading edge placed on the movable document table 54, which can swing in the directions of the arrows a and b in the figure according to the thickness of the stack of documents MS, and its trailing edge placed on the document placement platform 53. At this time, one end of the document in the width direction (direction perpendicular to the paper surface) on the document placement platform 53 abuts against the set reference portion 56a (see FIG. 7), and the other end abuts against the side fence 56b (see FIG. 7), thereby adjusting the position in the width direction. The document MS set in this way pushes up the lever member 62, which is arranged to be able to swing above the movable document table 54. Then, the document set sensor 63 detects the setting of the document MS and sends a detection signal to the controller 904. This detection signal is then sent from the controller 904 to the reading control unit 903 via the I/F.

The document placement tray 53 holds a first length sensor 57 and a second length sensor 58, which are reflective photosensors or actuator-type sensors that detect the length of the document MS in the transport direction. These length sensors detect the length of the document MS in the transport direction.

Above the stack of originals MS placed on the movable original table 54, there is disposed a pickup roller 80, a feeding member supported by a cam mechanism so that it can move up and down (in the directions of the arrows c and d in the figure). This cam mechanism can move the pickup roller 80 up and down when driven by a pickup motor 193. The movable original table 54 swings in the direction of the arrow a in the figure, and the pickup roller 80 comes into contact with the topmost original MS in the stack of originals MS. As the movable original table 54 rises further, the pickup roller 80 rises accordingly, and eventually the table rise sensor 59 detects that the movable original table 54 has risen to its upper limit. This stops the rise of the movable original table 54.

The operator operates the main body operation unit 902, which is composed of a numeric keypad, a display, etc., provided on the main body of the copier, to set the reading mode, indicating whether the reading mode is double-sided or single-sided, and to press the copy start key. In other words, the main body operation unit 902 functions as a mode information acquisition means for acquiring information on whether the reading mode is double-sided or single-sided. When the copy start key is pressed, a document feed signal is sent from the main body control unit 901 to the controller 904 of the ADF 51 via the I/F. Then, the pickup roller 80 is rotated by the forward rotation of the feed motor 191, and the document MS on the movable document table 54 is sent out from the movable document table 54.

When setting the double-sided or single-sided reading mode, it is possible to set both sides or single-sided all at once for all the documents MS placed on the movable document table 54. It is also possible to set the reading mode individually for each document MS, for example, to set the first and tenth documents MS to double-sided reading mode while setting the other documents MS to single-sided reading mode.

The document MS sent by the pickup roller 80 enters the separation conveying section B and is sent to the separation section, which is the contact position between the paper feed belt 84 and the separation roller 85. This paper feed belt 84 is stretched by the drive roller 82 and the driven roller 83, and is moved endlessly in the clockwise direction in the figure by the rotation of the drive roller 82 accompanying the forward rotation of the paper feed motor 191. The separation roller 85, which is rotated clockwise in the figure by the forward rotation of the paper feed motor 191, contacts the lower tension surface of this paper feed belt 84 to form a separation section. In the separation section, 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 it is directly contacting the paper feed belt 84 or when only one document MS is sandwiched in the contact section, it rotates with the belt or the document MS. However, when multiple sheets of originals MS are sandwiched in the contact area, the accompanying rotation force becomes lower than the torque of the torque limiter, so the rollers rotate in the opposite direction to the accompanying rotation, clockwise in the figure. As a result, the separation roller 85 applies a moving force in the opposite direction to the paper feed to the originals MS below the topmost sheet, and only the topmost sheet MS is separated from the several sheets of originals.

The document MS separated into one sheet by the action of the feed belt 84 and the separation roller 85 enters the registration section C. Then, when it passes directly under the abutment sensor 72, its leading edge is detected. At this time, the pickup motor 193 rotates, and the pickup roller 80 retreats from the top surface of the document. The document MS is transported only by the endless moving force of the feed belt 84. Then, the endless movement of the 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. After that, the leading edge of the document MS abuts against the abutment portion between the pull-out driven roller 86 and the pull-out drive roller 87 that is driven to rotate while abutting against it. With the leading edge of the document MS abutting against the abutment portion of both rollers, the rear end side of the document MS is sent in the paper feed direction, and the leading edge of the document MS is positioned at the abutment portion while being bent by a predetermined amount. As a result, the skew (inclination) of the document MS is corrected, and the document MS is aligned with the paper feed direction.

In addition to correcting the skew of the document MS, the pull-out drive roller 87 also transports the document MS with the skew corrected to the intermediate roller pair 66 downstream in the document transport direction. The pickup roller 80, the drive roller 82 that stretches the paper feed belt 84, the pull-out drive roller 87, and the drive roller of the intermediate roller pair are connected to the paper feed motor 191 via a one-way clutch. The one-way clutch connected to the pull-out drive roller 87 and the drive roller of the intermediate roller pair transmits the drive force when the paper feed motor 191 rotates in the reverse direction, and the one-way clutch connected to the drive roller 82 transmits the drive force when the paper feed motor 191 rotates in the forward direction. Therefore, when the paper feed motor 191 rotates in the reverse direction, the pull-out drive roller 87 and the drive roller of the intermediate roller pair 66 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.

The document MS sent out from the pull-out drive roller 87 passes directly below the document width sensor 73. The document width sensor 73 has multiple paper detection units consisting of reflective photosensors or the like, and these paper detection units are lined up in the document width direction (the direction perpendicular to the drawing sheet). The widthwise size of the document MS is detected based on which paper detection unit detects the document MS. In addition, 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.

The leading edge of the document MS, whose widthwise size has been detected by the document width sensor 73, enters the turn 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 transport section E, which will be described later. This shortens the time it takes for the document MS to be sent to the first reading and transport section E.

The leading edge of the document MS being transported through the turn 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 decelerated while the leading edge is transported to the position of the reading entrance roller pair (pair of 89 and 90) downstream in the transport direction. In addition, as the transport motor 192 starts to rotate, one roller in the reading entrance roller pair (89, 90), one roller in the reading exit roller pair 92, and one roller in the second reading exit roller pair 93 each start to rotate.

In the turn section D, the original MS is reversed upside down and the transport direction is reversed while being transported on the curved transport path between the intermediate roller pair 66 and the reading entrance roller pair (89, 90). Then, the leading edge of the original MS that has passed through the nip between the reading entrance roller pair (89, 90) passes directly below the registration sensor 65. When the leading edge of the original MS is detected by the registration sensor 65 at this time, the original transport speed is decelerated over a predetermined transport distance, and the transport of the original MS is temporarily stopped just before the first reading transport section E. In addition, a temporary stop signal is sent to the reading control section 903 via the I/F.

When the reading control unit 903 receives the pause signal and sends a reading start signal, the controller 904 controls the conveying motor 192 to resume rotation and increase the conveying speed of the document MS to a predetermined conveying speed until the leading edge of the document MS reaches the first reading conveying unit E. Then, at the timing when the leading edge of the document MS reaches the reading position by the first surface fixed reading unit 151, the controller 904 sends a gate signal indicating the sub-scanning direction effective image area of the first surface of the document MS to the reading control unit 903. This transmission continues until the rear end of the document MS leaves the reading position by the first surface fixed reading unit 151, and the first surface of the document MS is read by the first surface fixed reading unit 151. The timing when the leading edge of the document MS reaches the reading position by the first surface fixed reading unit 151 is calculated based on the pulse count of the conveying motor 192.

After passing through the first reading conveying section E, the document MS passes through the reading exit roller pair 92 described below, and its leading edge is detected by the paper discharge sensor 61. When the single-sided reading mode is set, it is not necessary to read the second side of the document MS by the contact image sensor 95 described below. When the leading edge of the document MS is detected by the paper discharge sensor 61, the driving force of the conveying motor 192 is connected to the paper discharge roller pair 94 by the paper discharge clutch 194, and the lower paper discharge roller in the paper discharge roller pair 94 is rotated clockwise in the figure. In addition, based on the pulse count of the conveying motor 192 after the leading edge of the document MS is detected by the paper discharge sensor 61, the timing at which the rear end of the document MS leaves the nip of the paper discharge roller pair 94 is calculated. Based on the result of this calculation, the paper discharge clutch 194 cuts off the driving force of the conveying motor 192 and stops the paper discharge roller pair 94.

On the other hand, when the double-sided reading mode is set, the timing until the leading edge of the original MS is detected by the discharge sensor 61 and then reaches the contact image sensor 95 is calculated based on the pulse count of the transport motor 192. Then, at that timing, the controller 904 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 903. This transmission continues until the trailing edge of the original MS leaves the reading position of the contact image sensor 95, and the second side of the original MS is read by the contact image sensor 95.

The contact image sensor 95 (CIS) as the second surface reading means has a coating applied to its reading surface 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 contact image sensor 95 as a document support means for supporting the document MS from the non-reading surface side (first surface side). This second reading roller 96 prevents the document MS from floating at the reading position by the contact image sensor 95, and also functions as a reference white area for acquiring shading data in the contact image sensor 95. This copier uses the second reading roller 96 as a document support means for supporting the document opposite the contact image sensor 95, but a guide plate-like roller may also be used.

Next, the characteristic features of this embodiment will be described.
7 is an explanatory diagram relating to the arrangement of a sound collecting microphone 803, an electromagnet 801, and a contact member 802. (a) is a schematic plan view, and (b) is a schematic side view.

A user may inadvertently place an original MS with a metal piece such as a staple or paperclip attached to it on the original placement tray 53. If a metal piece m such as a staple is attached to the trailing edge of the original, the metal piece m is exposed when the original MS is placed on the original placement tray 53, making it easy to notice the presence of the metal piece m before starting to transport the original. However, as shown in FIG. 7(a), when the original MS is placed on the original placement tray 53, the leading edge of the original is covered by the paper feed cover 98. As a result, if there is a metal piece m attached to the leading edge of the original MS, there is a high risk that the transport of the original MS will be started without noticing the metal piece m.

When an original MS with metal pieces such as staples or clips attached is transported, the metal pieces may damage components such as the transport roller. In addition, when the leading edge of a stack of multiple originals MS bound with metal pieces such as staples or clips enters the separation unit BN, the topmost original in the stack continues to be transported by the paper feed belt 84. However, the second and subsequent originals are given a return transport force by the separation roller 85. As a result, a large stress is applied to the parts bound with the metal pieces, which may cause the originals to tear, fold, or wrinkle, resulting in damage to the originals.
Therefore, in this embodiment, a metal detection means is provided for detecting metal pieces m attached to the document, and when the metal detection means detects the metal pieces m, transport of the document is stopped.

The metal detection means for detecting metal pieces m, such as staples or paperclips, attached to a document includes a contact member 802, an electromagnet 801 as a magnetic force generating means, and a sound collecting microphone 803 as a sound collecting means. The contact member 802 is disposed between the pickup roller 80 and the separation unit BN. The electromagnet 801 is disposed directly above the contact member 802.

In this embodiment, a holder 80a that holds the pickup roller 80 so that it can be brought into contact with and separated from the document placed on the movable document table 54 is disposed in the approximate center in the width direction. The contact member 802 and the electromagnet 801 are disposed on either side of the holder 80a in the width direction.

The contact member 802 may be made of any material that produces an abnormal sound different from the operating sound when the metal piece m of the document MS hits the contact member 802 and that allows the magnetic force of the electromagnet 801 to reach the document on the transport path. In particular, a material such as glass that produces a loud impact sound when the metal piece m hits it and has a high acoustic effect is preferable.

The sound collection microphone 803 is attached to the paper feed cover 98 and is disposed upstream of the pickup roller 80 in the document transport direction. The sound collection microphone 803 may be disposed in any position where it can collect the collision sound when the metal piece of the document MS collides with the contact member 802, such as in a dead space of the device. In this manner, in this embodiment, the sound collection microphone 803 can be disposed in a dead space of the device, which makes it possible to avoid a situation in which the device needs to be expanded to accommodate the sound collection microphone 803. As a result, the size of the device can be prevented from increasing.

In FIG. 7(a), reference numeral 56 denotes a set reference portion when setting the document MS, and reference numeral 55 denotes a side fence. When the document MS is set on the document placement tray 53, one end in the width direction abuts against the set reference portion 56a, and the other end abuts against the side fence 56b, thereby restricting the widthwise position. In other words, in this embodiment, the side fence 56b and the set reference portion 56a function as restricting members.

FIG. 8 is a diagram for explaining the detection of a metal piece m attached to a document MS.
When the pickup roller 80 feeds the document MS on the document placement table 53, the controller 904 energizes the electromagnet 801 to generate a magnetic force in the area of the document transport path facing the contact member 802. When the metal piece m attached to the document MS enters the area facing the contact member 802, the metal piece m is attracted to the contact member 802 by the magnetic force of the electromagnet 801. The magnetic force that attracts the metal piece m to the contact member 802 causes the periphery of the metal piece m of the document MS to float, and the metal piece m collides with the contact member 802 (see FIG. 8B). When the metal piece m collides with the contact member 802, an abnormal sound (collision sound) is generated. As a result, the abnormal sound (collision sound) is mixed with the operation sound collected by the sound collection microphone 803, resulting in a characteristic operation sound. This makes it possible to distinguish the operation sound from the operation sound during normal transport, and it is possible to detect that the metal piece m is attached to the document from the operation sound collected by the sound collection microphone 803.

In addition, in this embodiment, the contact member 802 is disposed upstream of the separation unit BN in the document transport direction, and the presence or absence of metal pieces m can be determined before the leading edge of the document MS reaches the separation unit BN, allowing the transport of the document MS to be stopped. This makes it possible to prevent the leading edges of multiple documents bound by the metal pieces m from entering the separation unit BN, thereby preventing the document MS from being torn, folded, or wrinkled, and thus reducing damage to the document MS.

It is also preferable to control the power supply to the electromagnet 801 on and off and repeatedly control the magnetic force on and off so that the metal piece m hits the contact member 802 multiple times. In this way, by hitting the metal piece m against the contact member 802 multiple times, it is possible to collect more distinctive operating sounds. This makes it possible to distinguish between normal transport and abnormal transport in which the metal piece m has come into contact with the contact member 802 with less learning data in machine learning, as described below.

In addition, since it takes a certain time from when the metal piece m collides with the contact member 802 until the operation sound is used to determine that abnormal transport is occurring and the paper feed operation is stopped, transport continues for a certain time even after the metal piece m collides with the contact member 802. As a result, if the electromagnet 801 is always turned on, the metal piece m contacts the contact member 802 due to the magnetic force, and the vicinity of the original MS where the metal piece m is attached is not transported. As a result, there is a risk of the original being wrinkled or folded. On the other hand, when the magnetic force is repeatedly controlled to be turned on and off, the original is transported when the magnetic force is off, so that it is possible to prevent the original from being wrinkled or folded due to bending of the original in the original transport path during the time until the operation sound is analyzed, abnormal transport is determined and the paper feed operation is stopped.
If it is difficult to control the magnetic force to be turned on and off multiple times while the metal piece m passes through the opposing area with the contact member 802, the magnetic force is generated constantly.

In addition, in this embodiment, the contact member 802 and electromagnet 801 are divided into multiple pieces so as not to interfere with the holder 80a, which is located approximately in the center of the width direction. However, in this embodiment, even if the contact member 802 and electromagnet 801 are divided into multiple pieces due to the arrangement of the components of the device, the presence or absence of metal pieces m can be detected for the end of the document set reference section 56a and the end of the side fence 56b with a single sound collection microphone 803. This makes it possible to prevent an increase in the number of parts and an increase in the cost of the device.

FIG. 9 is a flow chart showing the metal piece discrimination process executed by the controller 904.
As described above, when the document feed signal is sent from the main body control unit 901 to the controller 904, the document feed/separation operation starts (S1), and at the same time, the sound of the document feed/separation operation is collected by the sound collection microphone 803 (S2). In addition, the electromagnet 801 is energized to generate a magnetic force in the area facing the contact member 802 of the document transport path.

The controller 904 sequentially cuts out the collected operation sound data into frames of a predetermined length and calculates the Mel frequency cepstrum coefficient, which is a feature of the sound (S3). When repeatedly controlling the magnetic force ON/OFF so that the metal piece m hits the contact member 802 multiple times, it is preferable to cut out the operation sound data for a period of time equal to or longer than the time from when the metal piece m enters the opposing area facing the contact member 802 to when it leaves this opposing area. This makes it possible to record the impact sound of the metal piece m hitting the contact member 802 multiple times in the cut out operation sound data.

Mel frequency cepstral coefficients are features that are weighted by Mel frequency, taking into account human frequency perception characteristics, for the spectral envelope of speech (frequency characteristics derived from vocal tract components), and are often used as features for speech recognition.

The above "Mel frequency" is a frequency that is converted to take into account the human perception of pitch, whereby sounds near the lower limit of the audible range sound higher and sounds near the upper limit sound lower. A "cepstrum" is a frequency spectrum that is generated by taking the logarithm of an audio signal (waveform data) through a Fourier transform and converting it back to time space through an inverse Fourier transform. The "cepstrum" is also known as the "inverse Fourier transform of the logarithm of the spectrum" (spectrum of the spectrum), and is the separation of the fine structure of the spectrum (fine, subtle changes) from the gradual changes of the spectrum (spectral envelope).

Mel frequency cepstral coefficients are generally found as follows. That is, the amplitude spectrum found from the sound data is converted to Mel frequency, and then a Mel filter bank made up of overlapping triangular bandpass filters is used to compress the spectrum to 20 dimensions and find the Mel frequency spectrum. The Mel frequency spectrum thus found is then subjected to a discrete cosine transform to find the Mel frequency cepstrum, which separates the fine structure (fine, subtle changes) of the higher order component spectrum and the spectral envelope of the lower order components. The Mel frequency cepstrum coefficients are obtained by extracting the spectral envelope of the lower order components from this Mel frequency cepstrum.

Mel frequency cepstrum coefficients are generally obtained by extracting a spectral envelope consisting of 12 dimensions (12 pieces of data) and using it as a feature, and can express the features of audio data with a small amount of data. This reduces the calculation load on the controller 904. Note that the dimensions extracted from the Mel frequency cepstrum are not limited to 12 dimensions and can be determined as appropriate.

The Mel frequency cepstral coefficients are obtained by extracting the spectral envelope of sound, which is a frequency characteristic derived from vocal tract components. However, the spectral envelope of the operating sound during normal transport during paper feeding/separation operation and the spectral envelope of the operating sound when a metal piece m of the document collides with the contact member 802 are different from each other. Therefore, it is possible to determine whether or not a collision has occurred between the metal piece m of the document and the contact member 802, using the Mel frequency cepstral coefficients.

In this embodiment, the Mel frequency cepstrum coefficient is used as a feature that quantitatively expresses the characteristics of the operation sound used to determine whether the metal piece m of the document has collided with the contact member 802, but this is not limited to this. For example, a known sound feature such as a linear prediction coefficient may be used as the feature of the operation sound used to determine whether the metal piece m has collided with the contact member 802.

The calculated Mel-frequency cepstral coefficients are fed to a classifier using a support vector machine, which is a pattern recognition model that uses supervised learning, to determine the operating state (S4).

The support vector machine linearly separates and classifies multi-dimensional data into multiple classes. The support vector machine classifies the Mel frequency cepstral coefficients, which are the feature quantities of the operation sounds of the paper feeding/separation operations collected by the sound collection microphone 803, into either normal transport where no metal pieces are detected, or abnormal transport where a metal piece is detected. In other words, the Mel frequency cepstral coefficients calculated from the operation sounds collected from the collision sound when a metal piece m of the document collides with the contact member 802 are classified as abnormal transport. On the other hand, the Mel frequency cepstral coefficients calculated from the operation sounds where no collision sound is collected are classified as normal transport.

A support vector machine has high generalization performance with a small amount of training data, and can distinguish between normal and abnormal transportation with high accuracy. In this embodiment, a support vector machine is used as the classifier, but a classifier using a deep learning method may also be used.

When the support vector machine classifier classifies the given Mel frequency cepstrum coefficient as normal transport and determines that the transport is normal (no metal piece m), the document transport process described above is executed. That is, after the paper feed/separation operation is completed (S5), the paper feed motor 191 is reversed, and the pull-out operation (S6) is performed to send out the skew-corrected document by the pull-out drive roller 87, and then a registration process (S7) is performed to temporarily stop the transport of the document MS before the first reading and transport unit E. After that, the read control unit 903 waits for a reading start signal to be received (S8), and after receiving the signal, the transport of the document is resumed and the reading and transport process is started to transport the document sequentially to the first reading and transport unit E, the second reading and transport unit F, and the paper discharge unit G (S9).

On the other hand, when a metal piece m is attached to the document and the Mel frequency cepstral coefficients calculated from the operating sound when the metal piece m hits the contact member 802 and generates an abnormal sound are given, the classifier classifies the given Mel frequency cepstral coefficients as abnormal transport. If the classifier classifies the Mel frequency cepstral coefficients as abnormal transport (metal piece present), the drive of the feed motor 191 is stopped and the pickup motor 193 is caused to raise the pickup roller 80 to stop the paper feed/separation operation (S10). In addition to an alarm sound, a message such as "An abnormality in the transport of the document has been detected. Please check the document" is displayed on the display unit of the main body operation unit 902 to notify the user of the transport status (S11).

If the rear end of the document is stapled with metal pieces m such as staples, the leading edge of the document will enter separation section BN before the metal pieces m enter the opposing area with contact member 802. Then, there is a risk that transport will continue until the rear end of the document enters the opposing area with contact member 802. In this way, if transport continues after the leading edge of the document enters separation section BN, a large stress will be applied to the part stapled with metal pieces m, which may cause tears, folds, wrinkles, or other damage to the document.

When multiple documents whose rear ends are bound with a metal piece m such as a staple enter the separation section BN, the topmost document in contact with the paper feed belt 84 continues to be transported, but the second and subsequent documents are stopped by the separation roller 85. Therefore, the second and subsequent documents among the multiple documents whose rear ends are bound with a metal piece m such as a staple become a transport resistance for the topmost document, and slippage occurs between the topmost document and the pickup roller 80.

Therefore, it is possible to determine whether or not slippage has occurred between the pickup roller 80 and the document from the operating sound collected by the sound collecting microphone 803, and to stop the transport of the document when it is determined that slippage has occurred. This makes it possible to stop the transport of the document before the metal piece m, such as a staple needle, bound at the rear end of the document enters the opposing area with the contact member 802, thereby preventing tears or creases from occurring at the rear end of the document bound by the metal piece m.

Next, a modification of this embodiment will be described.
[Modification 1]
FIG. 10 is a schematic diagram showing a configuration of the first modified example.
10 , in the first modification, a contact member 802 and an electromagnet 801 are disposed below the document transport path from the pickup roller 80 to the separation unit BN. The contact member 802 is disposed below the guide surface of the document guide 88, and the electromagnet 801 is disposed below the contact member 802.

As shown in FIG. 10, no components are arranged near the center of the document width direction on the lower side of the document transport path, so a single contact member 802 and electromagnet 801 that is long in the document width direction can be arranged without dividing the contact member 802 and electromagnet 801 into multiple parts. This makes it possible to reduce the number of parts and reduce assembly labor, etc. In addition, in this variant 1, it is also possible to detect the metal piece m attached to the center of the document width direction.

FIG. 11 is a diagram for explaining detection of a metal piece m attached to a document in the first modification.
If the document MS does not have the metal piece m, the document fed by the pickup roller 80 is guided by the document guide 88 and moves to the separation section BN. On the other hand, if the document MS has the metal piece m, when the metal piece m of the document MS enters the facing area with the contact member 802, it is attracted to the contact member 802 by the magnetic force of the electromagnet 801. Then, the periphery of the metal piece m of the document bends downward and the metal piece m collides with the contact member 802 (see FIG. 10B), generating an abnormal sound (collision sound). Therefore, even in this modified example 1, the abnormal sound (collision sound) is mixed with the operation sound collected by the sound collecting microphone 803, resulting in a characteristic operation sound, and it is possible to detect that the metal piece m is attached to the document from the operation sound.

[Modification 2]
FIG. 12 is a schematic diagram showing a configuration of the second modification.
In the second modification, a contact member 802 and an electromagnet 801 are provided on a holder 80a that supports and raises and lowers the pickup roller 80, and the contact member 802 is disposed opposite the leading edge of the document placed on the document placement table 53. In the configuration shown in the second modification, it is possible to detect whether or not a metal piece m is attached to the document before the pickup roller 80 starts feeding.

Of multiple documents bound together with metal pieces m such as staples, the topmost document is subjected to a conveying force from the pickup roller 80, but no conveying force is applied to the other documents. This causes stress at the location of the bound metal pieces m, which can cause folds or wrinkles near the metal pieces m and damage the document. In the second variation, it is possible to detect whether or not the document has metal pieces m attached before feeding begins, thereby preventing damage to the document.

FIG. 13 is a diagram for explaining detection of a metal piece m attached to a document in the second modification.
As shown in FIG. 13A, when an original is set on the original placement table 53 and an instruction to read the original MS is given, the movable original table 54 rises. Then, the table lift sensor 59 turns ON, and when the position of the top surface of the original stack on the original placement table 53 is positioned at the paper feed position, the lift of the movable original table 54 stops. When the lift of the movable original table 54 stops, the electromagnet 801 is energized. If a metal piece m is attached to the tip of the original MS, as shown in FIG. 13B, the metal piece m is attracted by a magnetic force, the tip of the original MS floats, and the metal piece m collides with the contact member 802, generating an abnormal sound (collision sound). As a result, the abnormal sound (collision sound) is mixed with the operation sound collected by the sound collection microphone 803, and it is possible to detect that the metal piece m is attached to the original from the operation sound collected by the sound collection microphone 803.

In variant 2, the power supply to the electromagnet 801 is controlled to be turned on and off, and the magnetic force is repeatedly controlled to be turned on and off, so that the metal piece m hits the contact member 802 multiple times, thereby producing a distinctive operating sound.

When it detects that a metal piece m is attached to the document MS, it lowers the movable document table 54 and notifies the user by displaying a message such as "An abnormality has been detected. Please check the document" on the display unit of the main body operation unit 902 along with an alarm sound. On the other hand, if the operating sound picked up by the sound collection microphone 803 is normal, it drives the pickup roller 80 etc., and starts transporting the document.

It is preferable to continue detecting metal pieces m while the document is being transported by energizing electromagnet 801 to generate magnetic force even after the pickup roller 80 starts to drive. This allows detection of metal pieces m upstream of the leading edge of the document MS in the transport direction. When the abutment sensor 72 (see FIG. 5) detects the document and raises the pickup roller 80, the electromagnet 801 is de-energized to turn off the magnetic force. For the second and subsequent pages, when the pickup roller 80 is lowered and comes into contact with the topmost document MS on the document placement table 53, the electromagnet 801 is energized to detect metal pieces m.

[Modification 3]
FIG. 14 is a schematic diagram showing a configuration of the third modified example.
In the third modification, a contact member 802 and an electromagnet 801 are disposed at the downstream end of the side fence 56b in the document transport direction and at the downstream end of the set reference portion 56a in the document transport direction.

As with variant 2, variant 3 can detect the presence or absence of metal pieces m before the document is transported, preventing damage to the document MS. Furthermore, variant 3 can detect metal pieces m at both ends of the document MS in the width direction, even though the width direction length of the contact member 802 and electromagnet 801 is shorter than that of variant 2.

The contact member 802 and electromagnet 801 provided on the side fence 56b and the set reference portion 56a may be elongated in the transport direction within the range in which the sound collection microphone 803 can collect sound. With this configuration, it is possible to detect metal pieces m attached near both ends of the document in the width direction over a wide range in the transport direction.

FIG. 15 is a diagram for explaining an example in which the iron core 801b of the electromagnet 801 is used as a contact member.
Fig. 15(a) is a diagram showing an example in which the iron core 801b of the electromagnet 801 is used as a contact member in the configuration shown in Fig. 7, and Fig. 15(b) is a diagram showing an example in which the iron core 801b of the electromagnet 801 is used as a contact member in the configuration of Modification 1. Fig. 15(c) is a diagram showing an example in which the iron core 801b of the electromagnet 801 is used as a contact member in the configuration of Modification 2, and Fig. 15(d) is a diagram showing an example in which the iron core 801b of the electromagnet 801 is used as a contact member in the configuration of Modification 3.

As shown in Figures 15(a) to 15(d), the electromagnet 801 is composed of an iron core 801b and a coil 801a wound around the iron core 801b. A part of the iron core 801b is arranged in the same manner as the contact member shown in the embodiment and the modified example, and a part of the iron core 801b is used as a contact portion 802' against which a metal piece m attached to a document attracted by magnetic force comes into contact. Since the iron core 801b is a metal member, when the metal piece m attached to the document MS comes into contact with the iron core 801b, a characteristic loud collision sound is generated. Therefore, even when the iron core 801b of the electromagnet 801 is used as a contact member, it is possible to distinguish well between normal transport and abnormal transport in which the metal piece m collides with the iron core 801b from the operating sound collected by the sound collecting microphone 803, and it is possible to accurately detect the metal piece m of the document MS.

In addition, although an electromagnet is used as the magnetic force generating means in this embodiment, a permanent magnet may also be used. By using a permanent magnet, magnetic force can be generated with a simple configuration, and the cost of the device can be reduced compared to when an electromagnet is used. On the other hand, by using an electromagnet, the magnetic force can be controlled to be turned on and off, and as described above, the metal piece m can be collided with the contact member 802 multiple times, a more characteristic operating sound can be collected, and the metal piece m can be detected with high accuracy.

Even in a configuration using a permanent magnet, it is possible to turn on/off the magnetic force acting on the document by using a configuration as shown in Fig. 16. That is, the configuration is provided with a magnetic force shielding member 805 that reciprocates between a shielding position between a permanent magnet 804 and a contact member 802 and a retracted position.
When the magnetic force shielding member 805 is in the shielding position shown by the dashed line in the figure, the magnetic force of the permanent magnet 804 is shielded by the magnetic force shielding member 805 and the magnetic force does not reach the opposing region with the contact member 802 of the document transport path, so that the magnetic force acting on the document can be turned OFF. On the other hand, when the magnetic force shielding member 805 is in the retracted position shown by the solid line in the figure, the magnetic force of the permanent magnet 804 reaches the opposing region with the contact member 802 of the document transport path, so that the magnetic force acting on the document can be turned ON. Therefore, by moving the magnetic force shielding member 805 back and forth between the shielding position and the retracted position, it is possible to control the ON/OFF of the magnetic force.

Further, in the above description, an example in which the present invention is applied to the ADF 51 as a sheet feeding device has been described, but the present invention can also be applied to the blank paper feeder 40 as a sheet feeding device.
When a transfer paper, which is a sheet with an image printed on the front side, is reused as a backing paper, there is a risk that metal pieces such as staples and clips are forgotten to be removed and set in the paper feed cassette 42 of the blank paper supply device 40. As a result, as described above, there is a risk that metal pieces attached to the transfer paper may damage components such as the transport roller. Therefore, in the blank paper supply device 40, as described above, the contact member 802 and the electromagnet 801 are arranged between the delivery roller 43 and the separation roller 45 or on the side fence. Then, the sound of the metal pieces attached to the transfer paper attracted by magnetic force colliding with the contact member is collected by the sound collecting microphone 803 to determine whether or not metal is present. If it is determined that metal is attached, it is determined that there is an abnormality and feeding is stopped. This makes it possible to prevent components such as the transport roller from being damaged by metal pieces attached to the transfer paper.

The above description is merely an example, and each of the following aspects provides unique effects.
(Aspect 1)
In a sheet transport device equipped with a sheet mounting section such as an original mounting table 53 on which a sheet such as an original MS is placed, a sheet transporting means for transporting the sheet placed on the sheet mounting section, and a metal detection means for detecting metal attached to the sheet, the metal detection means comprises a magnetic force generating means such as an electromagnet 801, a contact member 802 with which metal such as a metal piece m attached to a sheet attracted by the magnetic force generating means comes into contact, and a sound collecting means such as a sound collecting microphone 803 capable of collecting sound when the contact member 802 comes into contact with the metal, and detects metal based on the sound collected by the sound collecting means.
In the metal detection means described in Patent Document 1, a space must be provided within the device for the actuator to swing, which may lead to an increase in the size of the device. Also, if the magnet member is divided into multiple parts due to the arrangement of device components such as a conveying roller arranged in the center of the sheet width direction, an actuator and a sensor must be provided corresponding to the magnet member, which may increase the number of parts and lead to an increase in the cost of the device.
In contrast, in the first aspect, the presence or absence of metal can be detected without a swinging member, and there is no need to secure space for the swinging member inside the device, which makes it possible to avoid an increase in size of the device. Also, the sound collection means only needs to be located in a place that can collect the sound when the metal comes into contact with the contact member, and it has a high degree of freedom in placement and can even be placed in dead space of the device. Therefore, it is possible to avoid a situation in which the device needs to be expanded to accommodate the sound collection means, and to prevent the device from becoming larger.
In addition, in aspect 1, the sound collecting means can collect the sound when the metal comes into contact with the contact member over a wide range. Therefore, even if the magnetic force generating means or the contact member is divided into multiple parts due to the component arrangement of the device, it is possible to collect the sound when the metal of each contact member comes into contact with the metal with a single sound collecting means. As a result, when the magnetic force generating means or the like is divided into multiple parts, it is possible to reduce the number of parts compared to the metal detection means of Patent Document 1, and to suppress an increase in the cost of the device.

(Aspect 2)
In aspect 1, the sheet transport means has a feeding member such as a pickup roller 80 that feeds a sheet placed on a sheet loading section such as the document loading tray 53, and a separation section BN that separates multiple sheets fed by the feeding member into one sheet, and the contact member 802 is positioned upstream of the separation section BN in the sheet transport direction.
According to this, as described in the embodiment, it is possible to determine whether or not metal is attached to a sheet such as an original MS before the leading edge of the sheet enters the separation unit BN. As a result, when it is detected that metal is attached to the sheet, the conveyance of the sheet can be stopped before the leading edge of the sheet enters the separation unit BN. This makes it possible to prevent the leading edge of a sheet stack bound by metal from entering the separation unit BN, and to prevent damage such as tears and folds from occurring to the sheets.

(Aspect 3)
In the first embodiment, the contact member 802 is disposed so as to face the sheet placed on the sheet placement portion such as the document placement table 53 .
According to this, it is possible to detect whether or not metal is attached to the sheet before starting sheet transport of the document MS, as described in Modifications 2 and 3. This makes it possible to prevent damage such as folds and wrinkles from occurring to the sheets bound with metal during transport.

(Aspect 4)
In aspect 3, the sheet transport means has a feeding member such as a pickup roller 80 that feeds a sheet placed on a sheet placement section such as the document placement table 53, and a contact member 802 and a magnetic force generating means such as an electromagnet 801 are provided on a holding member such as a holder 80a that holds the feeding member.
According to this, as described in the modified example 2, the contact member 802 can be made to face the sheet placed on the sheet placement section such as the document placement table 53, and a magnetic force can be applied to attract metal attached to the sheet placed on the sheet placement section to the contact member. This makes it possible to detect whether or not metal is attached to the sheet before the start of sheet conveyance.

(Aspect 5)
In aspect 3, sheet regulating members such as side fences 56b and set reference portions 56a that regulate the widthwise position of a sheet placed on a sheet placement portion such as the document placement tray 53 are provided, and magnetic force generating means such as a contact member 802 and an electromagnet 801 are provided on the sheet regulating members.
According to this, as described in the modified example 3, the contact member 802 can be made to face the sheet placed on the sheet placement section such as the document placement table 53, and a magnetic force can be applied to attract metal attached to the sheet placed on the sheet placement section to the contact member. This makes it possible to detect whether or not metal is attached to the sheet before the start of sheet conveyance.

(Aspect 6)
In any one of aspects 3 to 5, the metal detection means performs metal detection before the start of sheet transport.
This makes it possible to prevent damage such as folds and wrinkles from occurring to the metal-bound sheets during transport, as described in the second and third modified examples.

(Aspect 7)
In any one of Aspects 1 to 6, the magnetic force generating means is an electromagnet.
According to this, as described in the embodiment, the magnetic force can be controlled by controlling the current flowing through the coil 801a, and the magnetic force can be controlled by controlling the current flowing through the coil 801a in a space-saving configuration compared to the case of a permanent magnet. Also, the magnetic force acting can be adjusted by controlling the current flowing through the coil 801a.

(Aspect 8)
In any one of the first to sixth aspects, the magnetic force generating means is a permanent magnet.
This allows for a cheaper configuration than when an electromagnet is used as the magnetic force generating means, as described in the embodiment. Also, by using the magnetic force shielding member, it is possible to control the ON/OFF of the magnetic force acting on the sheet in the same way as with an electromagnet.

(Aspect 9)
In the seventh or eighth aspect, the metal detection means detects metal by repeatedly generating a state in which a magnetic force acts on the sheet and a state in which a magnetic force does not act on the sheet.
According to this, as described in the embodiment, metal such as the metal piece m can be collided with the contact member 802 multiple times, and more characteristic operation sounds can be collected by a sound collection means such as a sound collection microphone. This makes it possible to distinguish between normal operation sounds and operation sounds when the metal piece m comes into contact with the contact member 802 with less learning data in machine learning.

(Aspect 10)
In an automatic document feeder such as ADF 51 that includes a document feed section for feeding a document and feeds the document to an image reading section by the document feed section, any one of the sheet feeders of aspects 1 to 9 was used as the document feed section.
According to this, as described in the embodiment, it is possible to prevent the document transport section from being damaged by the metal of the document, and also to prevent the device from becoming larger and the cost of the device from increasing.

(Aspect 11)
In an image reading device such as a document reading device 50 having an automatic document feeder such as an ADF 51 and an image reading means such as a scanner 150 that reads an image on a document transported by the automatic document feeder, the automatic document feeder of aspect 10 is provided as the automatic document feeder.
This makes it possible to prevent the device from becoming larger and the cost of the device from increasing.

(Aspect 12)
An image forming apparatus including an image reading device such as a document reading device 50 and an image forming means for forming an image based on image information read by the image reading device, includes the image reading device according to aspect 11 as the image reading device.
This makes it possible to prevent the device from becoming larger and the cost of the device from increasing.

(Aspect 13)
An image forming apparatus that includes a sheet transport unit that transports a sheet such as a transfer paper and forms an image on the sheet transported by the sheet transport unit includes the sheet transport device according to any one of aspects 1 to 9 as the sheet transport unit.
This can prevent the metal of the sheet from damaging the conveying member that conveys the sheet, and also can prevent the device from becoming larger and the cost of the device from increasing.

1: Image forming unit 40: Blank paper supply device 41: Paper bank 42: Paper feed cassette 43: Feed roller 45: Separation roller 50: Document reader 51: ADF
53: Document placement tray 54: Movable document table 55: Document stack tray 56a: Set reference section 56b: Side fence 80: Pickup roller 80a: Holder 82: Drive roller 83: Driven roller 84: Paper feed belt 85: Separation roller 88: Document guide 98: Paper feed cover 150: Scanner 801: Electromagnet 801a: Coil 801b: Iron core 802: Contact member 802': Contact section 803: Sound collecting microphone 804: Permanent magnet 805: Magnetic force shielding member 901: Main body control section 902: Main body operation section 904: Controller A: Document setting section B: Separation transport section BN: Separation section C: Registration section D: Turn section E: First reading transport section F: Second reading transport section G: Paper discharge section H: Stack section MS: Document m: Metal piece

JP 2009-161334 A

Claims (12)

a sheet placement section for placing a sheet;
a sheet conveying means for conveying a sheet placed on the sheet placement section;
a metal detection means for detecting metal attached to the sheet,
the sheet conveying means has a feeding member that feeds the sheet placed on the sheet placement portion,
The metal detection means includes:
A magnetic force generating means;
a contact member with which the metal attached to the sheet attracted by the magnetic force generating means comes into contact;
a sound collecting means capable of collecting a sound generated when the contact member and the metal come into contact with each other,
Detecting the metal based on the sound collected by the sound collecting means ;
a magnetic force generating means for generating magnetic force for the magnetic sheet; a contact member for holding the magnetic sheet ; a sheet placement section for placing a sheet;
a sheet conveying means for conveying a sheet placed on the sheet placement section;
a metal detection means for detecting metal attached to the sheet,
a sheet regulating member for regulating a width direction position of a sheet placed on the sheet placement portion,
The metal detection means includes:
A magnetic force generating means;
a contact member with which the metal attached to the sheet attracted by the magnetic force generating means comes into contact;
a sound collecting means capable of collecting a sound generated when the contact member and the metal come into contact with each other,
Detecting the metal based on the sound collected by the sound collecting means;
a contact member and a magnetic force generating means provided on the sheet regulating member ; a sheet placement section for placing a sheet;
a sheet conveying means for conveying a sheet placed on the sheet placement section;
a metal detection means for detecting metal attached to the sheet,
The metal detection means includes:
A magnetic force generating means;
a contact member with which the metal attached to the sheet attracted by the magnetic force generating means comes into contact;
a sound collecting means capable of collecting a sound generated when the contact member and the metal come into contact with each other,
A state in which a magnetic force acts on the sheet and a state in which a magnetic force does not act on the sheet are repeatedly generated,
A sheet conveying device, comprising: a sound collector that detects the metal based on the sound collected by the sound collector . 4. The sheet conveying device according to claim 1,
the sheet conveying means includes a feeding member that feeds a sheet placed on the sheet placement section, and a separating section that separates the plurality of sheets fed by the feeding member into one sheet;
The sheet transport device according to claim 1, wherein the contact member is disposed upstream of the separation unit in a sheet transport direction. 5. The sheet conveying device according to claim 1 ,
The sheet conveying device, wherein the contact member is disposed so as to face the sheet placed on the sheet placement portion. 6. The sheet conveying apparatus according to claim 5 ,
The sheet transport device according to claim 1, wherein the metal detection means detects metal before starting transport of the sheet. 7. The sheet conveying device according to claim 1,
4. The sheet transport device according to claim 3, wherein the magnetic force generating means is an electromagnet. 7. The sheet conveying device according to claim 1,
4. The sheet conveying device according to claim 1, wherein the magnetic force generating means is a permanent magnet . A document transport unit that transports a document ,
In the automatic document feeder, the document is fed to an image reading unit by the document feed unit,
9. An automatic document feeder, comprising the sheet feeder according to claim 1 as said document feed section. An automatic document feeder;
an image reading device for reading an image on a document conveyed by an automatic document feeder,
10. An image reading apparatus comprising the automatic document feeder according to claim 9 as the automatic document feeder. An image reading device;
an image forming unit that forms an image based on image information read by the image reading device,
An image forming apparatus comprising the image reading device according to claim 10 as the image reading device. A sheet conveying unit that conveys a sheet is provided,
In an image forming apparatus that forms an image on a sheet conveyed by the sheet conveying unit,
An image forming apparatus comprising the sheet transport device according to claim 1 as the sheet transport section.