JP2021012139A - Sheet conveying device and image reading device - Google Patents

Abstract

To provide a configuration that can prevent erroneous detection of metal binding members, such as staples even if a conductor is brought near a feeding port.SOLUTION: A metal detection unit 20 has detection coils 21A, 21B, a resonance circuit, and a frequency calculator. The detection coil 21A is arranged near the downstream side of a feeding port E in a sheet conveyance direction. The detection coil 21B is arranged near the feeding port E and on the upstream side of the detection coil 21A in the sheet conveyance direction. The resonance circuit excites the detection coils 21A, 21B to generate a magnetic field. The frequency calculator calculates the amount of change in resonance frequency of each of the detection coils 21A, 21B. A control unit 15 determines if the metal detection unit 20 detects metal from frequency data that is the amount of change in resonance frequency of the detection coil 21A and a determination threshold. Together with this, the control unit 15 changes the determination threshold based on frequency data that is the amount of change in resonance frequency of the detection coil 21B.SELECTED DRAWING: Figure 1

Description

The present invention relates to a sheet conveying device for conveying a sheet and an image reading device for reading an image of the sheet.

As a sheet transport device for transporting sheets, a metal detection sensor that detects metal such as staples in a non-contact manner is fed to prevent the sheet as it is bound by binding members such as metal staples and clips from being transported. A configuration arranged in the vicinity of the mouth has been proposed (Patent Document 1). The metal detection sensor described in Patent Document 1 has a detection coil that generates a magnetic field, and detects metal by changing the magnetic field.

Japanese Unexamined Patent Publication No. 2013-134227

However, in the configuration in which the metal detection sensor is arranged near the feeding port as described in Patent Document 1, the magnetic field around the detection coil is generated even when a large conductor such as a hand approaches the feeding port while the sheet is being conveyed. Since it changes rapidly, it may be falsely detected as a staple.

An object of the present invention is to provide a configuration capable of suppressing erroneous detection of a metal binding member such as a staple even when the conductor is brought close to the feeding port.

The sheet transport device of the present invention includes a feeding means for feeding a sheet from a feeding port to the inside of the device, a first detection coil arranged in the vicinity of the feeding port on the downstream side in the sheet transport direction, and the feeding port. A magnetic field is excited by exciting a second detection coil, the first detection coil, and the second detection coil arranged in the vicinity of the feeding port and upstream of the first detection coil in the sheet transport direction. It has a magnetic field generation circuit for generating the above, and a detection means for detecting the amount of change in the magnetic field of each of the first detection coil and the second detection coil, and the metal is obtained based on the detection result of the detection means. From the detectable metal detecting means and the first detection value and the threshold value corresponding to the amount of change in the magnetic field of the first detection coil, it is determined whether the metal detecting means has detected the metal, and the second detection is performed. It is characterized by comprising a control means for changing the threshold value based on a second detected value corresponding to a change amount of a magnetic field of the coil.

Further, in the sheet transport device of the present invention, the feeding means for feeding the sheet from the feeding port to the inside of the device, the driving means for driving the feeding means, and the vicinity of the feeding port on the downstream side in the sheet transport direction. A first detection coil arranged in, a second detection coil arranged in the vicinity of the feed port and upstream of the first detection coil in the sheet transport direction, and the first detection. A magnetic field generation circuit that excites a coil and the second detection coil to generate a magnetic field, a detection means for detecting the amount of change in the magnetic field of each of the first detection coil and the second detection coil, and the detection. When the sheet bound by the metal binding member is conveyed from the feeding port based on the detection result of the means, the driving means if the binding member is in the detection region of the second detection coil. When the binding member is in the detection region of the first detection coil, the driving of the driving means is stopped, and the binding member is not bound by the binding member from the feed port. When the sheet is conveyed, based on the detection result of the detection means, when the sheet passes through the detection region of the first detection coil, the first detection coil and the first detection coil are more than the binding member. A control means that controls the drive means so that the drive means remains driven even if a conductor that affects the magnetic field around the detection coil 2 is arranged in the detection region of the second detection coil. It is characterized by having.

Further, in the sheet transport device of the present invention, a feeding means for feeding a sheet from a feeding port to the inside of the device, a detection coil arranged in the vicinity of the feeding port, and the detection coil at a first resonance frequency. A first resonance circuit to resonate, a second resonance circuit for resonating the detection coil at a second resonance frequency different from the first resonance frequency, and the detection coil to resonate with the first resonance circuit, or the above. A switching means for switching whether to resonate in the second resonance circuit and a frequency for calculating the first resonance frequency of the first resonance circuit or the second resonance frequency of the second resonance circuit resonated by the switching means. The metal having a calculation means and capable of detecting a metal based on the change amount of the first resonance frequency, and the metal from the first detection value and the threshold value corresponding to the change amount of the first resonance frequency. It is characterized in that it is provided with a control means for determining whether the detection means has detected metal and changing the threshold value based on the second detection value corresponding to the change amount of the second resonance frequency.

Further, in the sheet transport device of the present invention, a feeding means for feeding a sheet from a feeding port to the inside of the device, a driving means for driving the feeding means, and a detection coil arranged in the vicinity of the feeding port are provided. A first resonance circuit that resonates the detection coil at the first resonance frequency, a second resonance circuit that resonates the detection coil at a second resonance frequency different from the first resonance frequency, and the detection coil at the first resonance frequency. The switching means for switching between resonance in the resonance circuit 1 and resonance in the second resonance circuit, and the resonance frequency of the first resonance circuit or the second resonance circuit resonated by the switching means. When the frequency calculating means for calculating the resonance frequency and the sheet bound by the metal binding member are conveyed from the feeding port and the binding member is at a position overlapping the detection region of the detection coil, the first When the detection coil is resonated by the resonance circuit of the above, the driving of the driving means is stopped based on the calculation result by the frequency calculating means, and the detection coil is bound by the binding member from the feeding port. When transporting a sheet that has not been used, the first conductor that affects the magnetic field around the detection coil rather than the binding member when the sheet passes through a position that overlaps the detection region of the detection coil. The detection coil is provided with a control means for controlling the drive means so that the drive means remains driven even if the detection coil is arranged in the detection region of the detection coil in a state of being resonated by the resonance circuit of the above. It is characterized by that.

According to the present invention, even if the conductor is brought close to the feeding port, erroneous detection of a metal binding member such as a staple can be suppressed.

A cross-sectional view of a side view schematically showing an image reading device according to an embodiment. The schematic diagram which shows the structure of the metal detection part which concerns on embodiment. The figure explaining the arrangement of the metal detection part which concerns on embodiment. In the X portion of FIG. 1, an enlarged view showing (a) a state in which the hand is away from the feeding port and (b) a state in which the hand is approaching the feeding port. The graph which shows (a) the resonance frequency in the detection coil 21A and (b) the resonance frequency in the detection coil 21B when the hand is brought close to the feeding port. The graph which shows (a) the resonance frequency in the detection coil 21A and (b) the resonance frequency in the detection coil 21B when the sheet bound by the staple is conveyed. The graph which shows (a) the resonance frequency in the detection coil 21A and (b) the resonance frequency in the detection coil 21B when the sheet bound by the staple is conveyed with the hand close to the feeding port. When the sheet bound by staples is conveyed with the hand close to the detection coil 21B and far from the detection coil 21A, (a) the resonance frequency in the detection coil 21A and (b) the resonance frequency in the detection coil 21B are shown. Graph to show. The flowchart of the control of metal detection at the time of sheet feeding which concerns on embodiment. Another flowchart for controlling metal detection during sheet feeding according to the embodiment. The block diagram which shows the structure of the metal detection part which concerns on 1st Example of another Embodiment. (A) A diagram for explaining the arrangement of the metal detection unit according to the second example of another embodiment, and (b) a block diagram showing the configuration of the metal detection unit as well.

The embodiment will be described with reference to FIGS. 1 to 10. First, the schematic configuration of the image reading device of the present embodiment will be described with reference to FIGS. 1 and 2.

[Image reader]
The image reading device 100 includes a sheet conveying device 101 that conveys a sheet, and an image reading unit 40 that reads an image of a sheet (original) conveyed by the sheet conveying device 101. The sheet transport device 101 includes a feed tray 1, a separate feed mechanism 10, a transport unit 30, and a metal detection unit 20 as metal detection means.

The feed tray 1 can load a plurality of sheets. The feed tray 1 is configured to be able to move up and down (move) within the movable range A. The feed tray 1 may be configured not to move up and down. Further, the feed tray 1 abuts on both ends in the width direction of the sheets intersecting (orthogonally in the present embodiment) in the transport direction of the sheets loaded on the feed tray 1 to regulate the position in the width direction of the sheets. It has a plate 2.

The feed tray drive motor 3 as a moving means raises and lowers (moves) the feed tray 1. The sheet loading detection sensor 51 as the sheet loading detecting means detects that the sheet is loaded on the sheet loading surface 1b of the feeding tray 1. The sheet position detection sensor 52 indicates that when the feed tray 1 on which the sheet bundle is placed rises, the top of the sheet bundle reaches a position (feeding position) where the uppermost portion of the sheet bundle abuts on the feeding roller (pickup roller) 17, which will be described later. Detects when the seat pushes the lever.

The feeding roller 17 as a feeding means feeds the uppermost sheet loaded on the feeding tray 1 to the feeding port E which is the entrance of the transport path 90. The portion where the feeding roller 17 and the dotted line F in FIG. 1 overlap each other indicates a position where the sheet on the feeding tray 1 and the feeding roller 17 come into contact with each other. Actually, the position where the sheet and the feeding roller come into contact has a certain width with respect to the sheet conveying direction, but the center thereof is indicated by the dotted line F.

The feeding roller drive motor 16 is a drive source for rotating the feeding roller 17. FIG. 1 shows a state in which the upper surface of the sheet P is in contact with the feeding roller 17 (seat feeding position), and the sheet feeding starts when the feeding roller 17 is rotated. The feeding roller 17 is rotated by the feeding roller drive motor 16 so as to feed the uppermost sheet of the feeding tray 1 in the transport direction RT.

The separate feeding mechanism 10 includes a feeding roller (feeding rotating body) 11 as a feeding means and a separating roller 12 as a separating member. The feeding roller 11 is rotationally driven by a feeding motor 13 as a driving means, and feeds (conveys) the sheet from the feeding port E to the inside of the device in the direction of arrow RT. The separation roller 12 forms a nip portion N for niping a sheet with the feeding roller 11, separates the sheets loaded on the feeding tray 1 one by one, and feeds the sheets by the feeding roller 11. .. The nip portion N is a region where the separation roller 12 and the feeding roller 11 are in contact with each other. Such a separation roller 12 constantly receives a rotational force that rotates in a direction that pushes the seat upstream in the sheet transport direction from the separation motor 14 via a torque limiter (slip clutch) (not shown).

Further, the feeding motor 13 is a motor that supplies a driving force for rotating the feeding roller 11. Similarly, the separation motor 14 is a motor that supplies a driving force for rotating the separation roller 12. A sheet detection sensor 10a for detecting a sheet is arranged on the downstream side of the nip portion N of the separate feeding mechanism 10 in the sheet transport direction and on the upstream side of the pair of transport rollers 31 and 32 described later. The sheet detection sensor 10a detects the tip of the sheet fed by the feeding roller 17. When the seat detection sensor 10a detects the tip of the seat, the control unit 15, which will be described later, stops driving the feeding roller drive motor 16 and stops the rotation of the feeding roller 17. Further, the sheet detection sensor 10a detects the rear end of the sheet separated and conveyed by the separate feeding mechanism 10. When the control unit 15 described later detects the rear end of the sheet by the sheet detection sensor 10a, the feeding roller 17 conveys the next sheet.

Next, the details of the method of separating the sheets one by one by the feeding roller 11 and the separating roller 12 will be described. When there is one sheet between the feeding roller 11 and the separating roller 12, the feeding roller 11 is larger than the upper limit of the rotational force that pushes the sheet transmitted by the separating roller 12 to the upstream side via the torque limiter. The rotational force in the direction of transporting the sheet to the downstream side exceeds, and the separation roller 12 rotates following the feeding roller 11.

On the other hand, when a plurality of sheets are present between the feeding roller 11 and the separation roller 12, the separation roller 12 rotates in the direction of pushing back the sheets to the upstream side, and pushes back the sheets other than the uppermost sheet to the upstream side. By the action of the feeding roller 11 to convey the sheet to the downstream side and the action of pushing the sheet of the separation roller 12 back to the upstream side in this way, the sheet is fed so as to overlap the nip portion N of the feeding roller 11 and the separation roller 12. At that time, only the top sheet is transported to the downstream side, the other sheets are pushed back to the upstream side, and the overlapping sheets are separated. Therefore, the feeding roller 11 and the separating roller 12 form the sheet separating feeding mechanism 10 with two rollers.

As described above, by having the feeding roller 11 and the separating roller 12, the sheet transporting device 101 of the present embodiment transports the sheets loaded on the feeding tray 1 one by one from the feeding port E to the inside of the device. Transport to route 90.

The transport path 90 is formed between the upper transport guide 91 and the lower transport guide 92 by arranging the upper transport guide 91 and the lower transport guide 92 so as to face each other. A separation roller 12 is arranged on the upper transport guide 91, and a feed roller 11 is arranged on the lower transport guide 92.

Such a transport path 90 guides the sheet into the device from the upstream side of the separate feed mechanism 10 to the transport unit 30. In the present embodiment, the transport path 90 is a region between the most upstream side of the space sandwiched between the upper transport guide 91 and the lower transport guide 92 and a pair of transport rollers (convey roller pairs) 37 and 38 described later. Point to. The sheet fed by the separate feeding mechanism 10 as described above moves along the upper transport guide 91 or the lower transport guide 92 to a pair of transport rollers (transport roller pairs) 31 and 32 described later.

The upper transport guide 91 as a transport guide for forming the transport path 90 has a first guide portion 91a and a second guide portion 91b so as to form one side of the transport path 90 from the feeding roller 17 to the transport roller 38. It is located in. The lower transport guide 92 has a first guide portion 92a and a second guide portion 92b, and is configured to form the other side of the transport path 90 from the supply port E to the transport roller 37. The shapes of the upper transport guide 91 and the lower transport guide 92 will be described in detail below.

The first guide portion 91a of the upper transport guide 91 is arranged along the transport direction of the sheet transported in the transport path from the upstream side of the separate feed mechanism 10. That is, the first guide portion 91a is arranged so as to be substantially parallel to the transport direction of the sheet transported in the transport path 90. The first guide portion 91a is arranged on the opposite side of the first guide portion 92a of the lower transport guide 92, which will be described later, with a gap of about several mm (for example, 5 mm or less).

The second guide portion 91b of the upper transport guide 91 is provided upstream of the first guide portion 91a in the sheet transport direction, and guides the sheet fed to the feeding roller 17 toward the first guide portion 91a. In the present embodiment, the second guide portion 91b smoothly feeds the bent or wrinkled sheet to the downstream side of the transport path 90, so that the sheet is further upstream from the upstream end of the first guide portion 91a in the sheet transport direction. It is tilted away from. In other words, the second guide portion 91b, which is a portion on the upstream side of the upper transport guide 91, is inclined in the direction toward the lower transport guide 92 toward the downstream side in the sheet transport direction. Therefore, the second guide portion 91b is formed so as to be separated from the lower transport guide 92 than the first guide portion 91a.

The first guide portion 92a of the lower transport guide 92 is arranged to face the first guide portion 91a of the upper transport guide 91, and is arranged along the transport direction of the sheet transported in the transport path from the upstream side of the separate feed mechanism 10. Have been placed. That is, the first guide portion 92a is also arranged so as to be substantially parallel to the transport direction of the sheet transported in the transport path 90.

The second guide portion 92b of the lower transport guide 92 is provided upstream of the first guide portion 92a in the sheet transport direction, and is a wall surface on which the tip of the sheet bundle loaded on the feed tray 1 abuts. In the present embodiment, the second guide portion 92b is composed of an inclined surface or a curved surface that is smoothly continuous with the upstream end of the first guide portion 92a and a wall surface formed substantially perpendicular to the inclined surface or the curved surface. ..

The dotted line C in FIG. 1 is a line indicating the boundary between the first guide portion 91a and the second guide portion 91b of the upper transport guide 91 and the first guide portion 92a and the second guide portion 92b of the lower transport guide 92. Further, the region where the dotted line C and the transport path 90 intersect is the supply port (opening) E which is the entrance of the transport path. The transport path 90 on the downstream side is used as a transport path, and the transport path 90 on the upstream side is used as a feed path. That is, the portion where the first guide portion 91a and the first guide portion 92a face each other is the transport path, and the portion corresponding to the second guide portion 91b is the feed path. In the present embodiment, in the cross-sectional view of the side view as shown in FIG. 1, the upstream side of the feeding port E is configured so that the second guide portion 91b and the second guide portion 92b form a fan shape. Further, when the tip of the sheet fed by the feeding roller 17 reaches the dotted line D, the sheet is brought into contact with the nip portion N of the feeding roller 11 and the separation roller 12. The dotted line D is a line indicating the center of the nip portion N of the feeding roller 11 and the separating roller 12 in the sheet transport direction.

In the vicinity of the feeding port E, the detection coil 21A of the metal detection unit 20, which will be described in detail later, is arranged on the upper transport guide 91 along the transport direction (sheet transport direction) RT. Further, the detection coil 21B of the metal detection unit 20 is arranged on the upstream side of the detection coil 21A of the upper transport guide 91 in the transport direction RT. The metal detection unit 20 includes detection coils 21A and 21B, resonance circuits 22A and 22B, frequency calculators 23A and 23B, and the amount of change in resonance frequency due to the approach of a metal binding member such as a staple or a conductor such as a hand. To measure. Details of the configuration and arrangement of the metal detection unit 20 and the method of detecting a metal binding member such as staples will be described later.

The transport unit 30 is arranged on the RT downstream side of the pair of transport rollers 31 and 32 and the pair of transport rollers 31 and 32 for transporting the sheet by using the transport motor 39 as a power source, and also transports the sheet. It has 33, 34, a pair of transfer rollers 35, 36 arranged further downstream, and a pair of transfer rollers 37, 38.

The transfer roller 31, the transfer roller 33, the transfer roller 35, and the transfer roller 37 are rotationally driven by the transfer motor 39, and the transfer roller 32, the transfer roller 34, the transfer roller 36, and the transfer roller 38 are driven to rotate, respectively. The above roller pair conveys the sheet to the downstream side. Further, an image reading unit 40 described later is arranged between the pair of transport rollers 31 and 32 and the pair of transport rollers 33 and 34.

The transfer motor 39 is a motor that supplies a driving force for rotating the transfer roller 31, the transfer roller 33, the transfer roller 35, and the transfer roller 37. Further, the control unit 15 described later controls the transfer motor 39 so as to change the rotation speed according to the optimum speed for reading the sheet and the setting of the reading resolution.

A pre-reading sheet sensor 43 is arranged on the downstream side of the pair of transport rollers 31 and 32 on the upstream side and on the upstream side of the image reading unit 40 described later. The pre-reading sheet sensor 43 is a sensor that detects a sheet to be conveyed. Further, based on the detection state of the pre-reading sheet sensor 43, the control unit 15 described later determines the timing at which the image reading unit 40 described later starts reading the image of the conveyed sheet, and also determines the timing at which the image of the conveyed sheet is started. Count the number of sheets.

The image reading unit 40 has a pair of reading units 41 and 42 that read the front and back surfaces of the sheet. The reading units 41 and 42 of the image reading unit 40 read images on both sides or one side of the sheet moving in the transport direction RT along the transport path 90. Such an image reading unit 40 can change the scanning interval based on the setting of the reading speed and the resolution. Further, the reading units 41 and 42 of the image reading unit 40 start reading the image of the sheet immediately after the sheet sensor 43 before reading detects the sheet to be conveyed.

The sheet whose image has been read by the image reading unit 40 moves in the order of the transfer rollers 33, 34, the transfer rollers 35, 36, and the transfer rollers 37, 38, and is discharged to the discharge tray 6. The transport path 90 is curved as shown in FIG. 1, and the sheet transported in the transport path 90 is discharged to the discharge port E and the discharge tray 6 arranged above the separate feed mechanism 10. ..

The discharge tray 6 is a tray for loading sheets discharged to the outside of the device from the transport rollers 37 and 38 as discharge means. Further, the discharge tray 6 can be moved up and down between the movable ranges B by the driving force of the discharge tray drive motor 7. In the present embodiment, the initial position of the discharge tray 6 is assumed to be the lowermost part of the movable range B.

The discharge tray drive motor 7 as an elevating means is a motor that supplies a driving force for elevating and lowering the discharge tray 6 at a speed instructed by the control unit 15. The discharge tray sensor 8 detects that the discharge tray 6 is at the uppermost position of the movable range B. The discharge sensor 9 as the discharge detection means detects that the sheet to be transported has been discharged to the discharge tray 6 by detecting the sheet to be transported. That is, the discharge sensor 9 detects that the sheet conveyed by the transfer rollers 37 and 38 has been discharged to the outside of the apparatus. Further, the control unit 15 counts the number of ejected sheets based on the detection state of the ejection sensor 9. The discharge tray 6 of the present embodiment configured as described above rises to the uppermost position of the movable range B before the sheet transfer starts. After starting the transfer of the sheet, the discharge tray 6 descends as the sheet is discharged. The discharge tray 6 may be configured not to move up and down.

The control unit 15 as a control means controls the entire image reading device 100. In the control of the entire image reading device 100, for example, in the present embodiment, when the start button (not shown) provided in the image reading device 100 is pressed, or when the information processing device connected to the image reading device 100 presses a reading start instruction, the control unit issues a reading start instruction. At the time of inputting to 15, the control unit 15 executes a series of processes such as sheet transport control, image reading unit 40 control, and metal detection unit 20 control described later. That is, the control unit 15 controls the drive of each motor built in the image reading device 100 and acquires the detection state of the sensor. Further, the control unit 15 separates and feeds all the sheets loaded on the feeding tray 1 based on the detection states of the sheet loading detection sensor 51 and the discharging sensor 9, and discharges them to the outside of the apparatus. 10 and the transport unit 30 are controlled.

Such a control unit 15 has a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory) (not shown). The control unit 15 controls each unit while reading a program corresponding to the control procedure stored in the ROM by the CPU. Further, the RAM is used as a storage area for storing work data, input data, frequency data output by the metal detection unit 20 described later, and the number of sheets to be conveyed. Further, the control unit 15 controls by referring to the data stored in the RAM based on the above-mentioned program or the like by the CPU. Further, the control unit 15 can change the settings of the frequency calculators 23A and 23B by rewriting the register values inside the frequency calculators 23A and 23B described later by the CPU via a communication line (not shown).

The image reading device 100 configured in this way separates and feeds the sheets loaded on the feeding tray 1 into the device one by one, reads the image of the sheets, and sequentially loads the sheets after reading the images on the discharge tray 6. .. Further, in the sheet transport device 101 of the present embodiment, after the sheet detection sensor 10a detects the rear end of the transported sheet, the sheet on the feed tray 1 is fed by the feeding roller 17, and the sheet is fed from the feed tray 1. The sheets are continuously conveyed until there is no more, and the sheets after reading the image are sequentially loaded on the discharge tray 6.

[Metal detector]
Next, the arrangement and configuration of the metal detection unit 20 as the metal detection means will be described. FIG. 2 shows the configuration of the metal detection unit 20, and the metal detection unit 20 includes detection coils 21A and 21B, resonance circuits 22A and 22B as magnetic field generation circuits, and a frequency calculator 23A as a detection means and a frequency calculation means. , 23B and. Such a metal detection unit 20 detects metal based on the amount of change in the magnetic field generated by exciting the detection coils 21A and 21B. Specifically, as shown in FIG. 3, the detection coil 21A as the first detection coil is arranged in the vicinity of the supply port E on the downstream side in the sheet transport direction. On the other hand, the detection coil 21B as the second detection coil is arranged in the vicinity of the feeding port E and on the upstream side in the sheet transport direction with respect to the detection coil 21A. Further, in the present embodiment, the distance D1 from the boundary between the feeding port E and the transport path to the detection coil 21A and the distance D2 from the feeding port E to the detection coil 21B are arranged so as to be equal.

The arrangement of the detection coils 21A and 21B of the metal detection unit 20 of the present embodiment will be described below. The detection coils 21A and 21B are arranged in the vicinity of the feeding port E as shown in FIGS. 1 and 3. Further, as described above, the detection coil 21A is arranged in the vicinity of the feeding port E on the downstream side in the sheet transport direction, and the detection coil 21B is arranged on the upstream side in the sheet transport direction with respect to the detection coil 21A. In particular, the detection coil 21A is arranged on the upstream side in the sheet transport direction with respect to the nip portion N. That is, as shown in FIG. 1, the detection coil 21A is located on the upstream side of the center (dotted line D) of the nip portion N in the sheet transport direction, and of the first guide portion 91a and the second guide portion 91b of the upper transport guide 91. It is arranged on the downstream side of the dotted line C indicating the boundary. Further, in the present embodiment, the detection coil 21A is arranged so that its plane is along the first guide portion 91a.

On the other hand, the detection coil 21B is arranged on the upstream side in the sheet transport direction with respect to the supply port E. In the present embodiment, the detection coil 21B is arranged so that its plane is along the second guide portion 91b. Therefore, the detection coil 21B is arranged at a position off the same plane as the detection coil 21A, and in the present embodiment, the detection coil 21B is arranged at an angle with respect to the detection coil 21A. Here, when the detection coil 21A and the detection coil 21B are arranged on the same plane, the magnetic fields formed by the respective detection coils are combined, which affects the amount of change in each magnetic field. Therefore, it is preferable that the detection coils 21A and 21B are not arranged on the same plane, and in the present embodiment, the detection coils 21B are arranged so as to be inclined with respect to the detection coil 21A. The inclination angle of the detection coil 21B with respect to the detection coil 21A is preferably 90 ° in a state where the detection coil 21B is displaced from the detection coil 21A or the sheet transport direction. In the present embodiment, the detection coil 21B is arranged so that its plane is along the second guide portion 91b.

Further, since the detection coil 21B is arranged on the side of the second guide portion 91b, the distance to the sheet conveyed from the feeding port E is arranged at a position farther than the detection coil 21A. Further, as shown in FIG. 3, the distance D1 from the feeding port E (dotted line C) to the detection coil 21A and the distance D2 from the feeding port E (dotted line C) to the detection coil 21B shall be substantially the same. Is preferable.

Two detection coils 21A may be arranged. Even in this case, the respective detection coils 21A are arranged between the dotted line D and the dotted line C on both sides of the feeding roller 11 of the upper transport guide 91 in the width direction. Further, the detection coil 21A is arranged at a position deviated from the feed roller 11 in the width direction intersecting the sheet transport direction. As long as a plurality of detection coils 21A are arranged, the number of detection coils 21B may be the same as the number of detection coils 21B, or may be smaller than that (for example, one).

By arranging the detection coils 21A and 21B in the vicinity of the feeding port E in this way, a metal binding member (hereinafter, collectively referred to as a staple) such as a staple for binding the sheet is formed on the detection coil 21A of the metal detection unit 20. The resonance frequency changes in proportion to the change in the state of the magnetic field around the detection coil 21A due to electromagnetic induction generated by approaching or separating from. On the other hand, since the detection coil 21B is farther from the sheet to be conveyed than the detection coil 21A, the resonance frequency is substantially unchanged even if the sheet bound by staples is conveyed. Further, when a conductor such as a hand approaches the feeding port E from the outside, the resonance frequency of both the detection coil 21A and the detection coil 21B changes at the same time. Hereinafter, a specific description will be given.

First, the configuration of the detection coil 21A as the first detection coil arranged on the downstream side in the sheet transport direction in the metal detection unit 20 will be described in detail below with reference to FIGS. 2A and 2B. The case where the metal detected by the metal detection unit 20 is a staple for binding the sheet bundle will be described below, but the same applies to, for example, a metal clip or the like.

The detection coil 21A is a flat coil formed as a pattern on a printed circuit board with a conductor such as copper foil. The number of turns of the detection coil 21A in the present embodiment is assumed to be the number of turns that is connected to the resonance circuit 22A and resonates at a resonance frequency of about 300 kHz to 500 kHz, which is highly sensitive to staples. The frequency with high sensitivity to the staple refers to the frequency band in which the amount of change in the resonance frequency is large when the staple approaches or a minute external noise affects the magnetic field around the detection coil. The form of the detection coil 21A is not limited to the above, and may be a coil formed by winding a conductor. Further, the resonance frequency of the resonance circuit 22A may be a frequency band that changes sufficiently depending on the approach of the staples carried together with the sheet.

The resonance circuit 22A as the first resonance circuit is a circuit that resonates by being connected to the detection coil 21A. Further, the resonance circuit 22A includes a resonance capacitor (not shown) shown in FIGS. 2 (a) and 2 (b). The resonance conditions of the detection coil 21A and the resonance circuit 22A are determined by the inductance component of the detection coil 21A, the capacitance component of the resonance capacitor, and the parasitic capacitance. Further, in the resonance circuit 22A of the present embodiment, it is assumed that the resonance condition is set so that the resonance frequency changes when the staple approaches the detection coil 21A to a distance of several mm (for example, 5 mm or less). When the resonance frequency changes with a small metal called a staple, the resonance frequency of the resonance circuit 22A changes even if the hand approaches the feeding port E.

The frequency calculator 23A as the first frequency calculation means calculates the resonance frequency from the output voltage or output current of the resonance circuit 22A. Specifically, the frequency calculator 23A is an IC that calculates the resonance frequency by taking in the periodic voltage change of the resonance circuit 22A. Further, the frequency calculator 23A obtains digital data (first detection value, hereinafter, frequency) of the magnitude of the frequency (change amount of the resonance frequency) changed from the resonance frequency in the state where there is no conductor moving around the detection coil 21A. Convert to data A). The frequency data A of the present embodiment has a minimum value of 1, and outputs frequency data to the control unit 15 via a communication line (not shown).

Next, in the metal detection unit 20, the configuration of the detection coil 21B as the second detection coil arranged on the upstream side in the sheet transport direction is the same as the configuration of the detection coil 21A, FIGS. 2A and 2B. Will be described in detail below with reference to.

The detection coil 21B is also a flat coil formed as a pattern on a printed circuit board with a conductor such as copper foil. It is assumed that the number of turns of the detection coil 21B is the same as that of the detection coil 21A or the number of turns that resonates with the resonance circuit 22B described later at a frequency lower than that of the resonance circuit 22A with respect to the staples. A frequency with low sensitivity to staples is, for example, a frequency of 1 MHz or higher, and the amount of change in resonance frequency is small even if the staples approach or minute external noise affects the magnetic field around the detection coil. Refers to the frequency band. The form of the detection coil 21B is not limited to the above, and may be a coil formed by winding a conductor. The resonance frequency of the resonance circuit 22B may be a frequency band that changes significantly when a large conductor such as a hand approaches the feeding port E.

The resonance circuit 22B as the second resonance circuit is a circuit that resonates by connecting to the detection coil 21B, and includes a resonance capacitor (not shown) in FIGS. 2 (a) and 2 (b). As described above, the resonance frequency of the resonance circuit 22B (for example, 1 MHz or more) is higher than the resonance frequency of the resonance circuit 22A (for example, 300 kHz to 500 kHz).

The frequency calculator 23B as the second frequency calculation means calculates the resonance frequency from the output voltage or output current of the resonance circuit 22B. Specifically, the frequency calculator 23B is an IC that calculates the resonance frequency by capturing the periodic voltage change of the resonance circuit 22B. Further, the frequency calculator 23B obtains digital data (second detection value, hereinafter, frequency) of the magnitude of the frequency (change amount of the resonance frequency) changed from the resonance frequency in the state where there is no conductor moving around the detection coil 21B. Converted to data B). The frequency data B of the present embodiment has a minimum value of 1, and outputs the frequency data B to the control unit 15 via a communication line (not shown).

The control unit 15 takes in the frequency data A and the frequency data B described above. The frequency data A corresponds to the first detection value corresponding to the amount of change in the magnetic field of the detection coil 21A. Further, the frequency data B corresponds to the second detection value corresponding to the amount of change in the magnetic field of the detection coil 21B. The control unit 15 determines whether the metal detection unit has detected the metal from the frequency data A and the determination threshold value Th as a threshold value described later. At the same time, the control unit 15 changes the determination threshold value Th based on the frequency data B. This point will be described later.

[Mask size]
In the case of the present embodiment, the control unit 15 includes an averaging filter circuit 24A and 24B (hereinafter collectively referred to as an averaging filter circuit 24) that capture a plurality of frequency data A and frequency data B and calculate an average value. .. The averaging filter circuits 24A and 24B of the present embodiment can set individual mask sizes. The mask size described in the present embodiment is the number of values for which the average is calculated. For example, when the mask size is set to 3, the averaging filter circuit calculates the average value of the three frequency data.

Here, the setting of the mask size of the averaging filter circuit 24 in the present embodiment will be described. In the present embodiment, since the detection coil 21B is arranged outside the device of the detection coil 21A, the frequency data B is more susceptible to external noise such as the approach of a hand or the surrounding environment than the frequency data A. On the other hand, the frequency data A is less susceptible to external noise because the detection coil 21A is inside the device than the detection coil 21B, but because the distance to the staples that move with the seat is short, FIG. 6 (a) described later. ), Since the change of the frequency data A is steep, the change of the frequency data A may be small due to the averaging.

From the above, the mask size of the frequency data B is set to be larger than the mask size of the frequency data A. That is, the control unit 15 samples the average value of the frequency data B rather than the number of samples (frequency data A) corresponding to the amount of change in the magnetic field of the detection coil 21A in order to obtain the average value of the frequency data A. The number of samples (frequency data B) corresponding to the amount of change in the magnetic field of the detection coil 21B is set to be larger in order to obtain.

It is desirable that the mask size of the frequency data B is set large within a range in which the frequency data B changes sufficiently greatly due to the approach of the hand. On the other hand, it is desirable that the mask size of the frequency data A is set to the minimum setting value so that the change of the frequency data A at the moment of passing directly under the detection coil 21A is maximized.

By setting the mask size as described above, there is an effect of suppressing an unintended change of the frequency data B due to external noise and stabilizing the staple detection based on the change of the frequency data A described later. That is, the sensitivity of detection by the detection coil 21B is made slower than the sensitivity of detection by the detection coil 21A (spatial resolution is lower), and the influence of noise on the detection coil 21B outside the device than the detection coil 21A is suppressed. , The detection accuracy of staples by the detection coil 21A is ensured.

In the present embodiment, as described above, the resonant circuit 22A is resonated in a frequency band that changes frequently when the staples approach, and the resonant circuit 22B resonates in a frequency band that does not easily change when the staples approach. By setting the resonance frequencies of the two resonance circuits 22 in this way, the amount of change in the resonance frequency due to the approach of the staples is increased for the resonance circuit 22A, and a small metal such as a staple is used for the resonance circuit 22B. It is possible to reduce the change in resonance frequency due to external noise or momentary external noise. Further, even if the mask size setting of each frequency data is the same value, the same effect as described above can be exhibited.

By setting the mask size as described above and setting the resonance frequencies of the resonance circuit 22A and the resonance circuit 22B, the sheet transfer device 101 of the present embodiment is more stable based on the metal determination process using the frequency data A described later. And the staple can be detected.

Further, by configuring the metal detection unit 20 as described above and measuring the change in the resonance frequency proportional to the change in the magnetic field around the detection coil as a detection value indicating the amount of change in the magnetic field, the metal is space-saving and inexpensive. The detection unit 20 can be configured. The detection value indicating the amount of change in the magnetic field around the excited detection coil may detect the inductance of the detection coils 21A and 21B in proportion to the amount of change in the magnetic field, or a magnetic field strength measuring instrument in the vicinity of the detection coil. May be placed and detected.

[Frequency data A and B when the hand approaches the air supply port]
As described above, the metal detection unit 20 connects the detection coils 21A and 21B, the resonance circuits 22A and 22B, the frequency calculators 23A and 23B, and the control unit 15 to generate a magnetic field around the energized detection coil 21A. Detects staples that have entered the (detection area). Here, in the present embodiment, by arranging the detection coil 21A of the metal detection unit 20 in the vicinity of the feeding port E, the magnetic field around the detection coil 21A is generated before the stapled sheet is conveyed and separated. I try to change it depending on the staples.

However, even if a large conductor such as a hand approaches the feeding port E while the sheet is being conveyed, the magnetic field around the detection coil changes rapidly, so that this may be erroneously detected as a staple. Therefore, in the present embodiment, the magnetic field (detection region) generated around the energized detection coil 21B is entered so that false detection of staples does not occur even if a conductor such as a hand approaches the air supply port E. Using the amount of change in the magnetic field due to the conductor, the metal detection determination process is performed by changing from the preset determination threshold Th0 to the determination threshold Th. Hereinafter, the frequency data A and B when the hand approaches the feeding port and the determination threshold value Th of the metal detection determination process will be described.

[Relationship between the resonance frequency and the judgment threshold Th when the hand approaches when transporting the sheet]
Here, the outline of the metal detection determination process and the determination threshold value change process will be described. The metal detection determination process of the present embodiment compares the frequency data A with the determination threshold value Th, and if the frequency data A is equal to or greater than the determination threshold value Th, it is determined that the staple that closes the sheet has passed directly under the detection coil 21A. .. Further, an example will be described of the relationship between the resonance frequency and the determination threshold value Th when the stapled sheet is conveyed and when the hands approach each other. The judgment threshold Th is changed by the judgment threshold change process, and in the judgment threshold change process, the frequency data B and the preset judgment threshold Th0 are added by the addition circuit 27, and the judgment threshold Th0 is the value after addition. This is the process of changing to Th.

[Resonance frequency when hands approach]
First, an example will be described of changes in the resonance frequency when the stapled sheet is conveyed and when the hands approach each other. 4 (a) and 4 (b) are enlarged views of the X portion of FIG. 1, in which a bundle of sheets is loaded on the feed tray 1 and the control unit 15 sets the sheet P1 at the top of the sheet bundle Px. The state before the start of the transport control of transporting by the feeding roller 17 is shown. Further, FIG. 4 (a) shows a state in which the hand as a conductor does not affect the metal detection unit 20 (hereinafter referred to as state A), and FIG. 4 (b) shows a state in which the hand is the feeding port E. Indicates a state in which the detection coil 21B is in the detection region (hereinafter referred to as state B).

Next, the change in frequency data when the position of the hand moves in the order of state A, state B, and state A will be described with reference to FIG. In the following description, the time when the hand starts moving from the state A to the state B is T0, the time when the hand position becomes the state B is T1, and the hand moves away from the position B to the position A. The time of movement will be described as T2.

5 (a) and 5 (b) are graphs showing frequency data when the hands are brought close to each other when the sheets are not conveyed or the sheets bound by staples are not conveyed. The solid line in FIG. 5A shows the frequency data A of the resonance circuit 22A connected to the detection coil 21A, and FIG. 5B shows the frequency data B of the resonance circuit 22B connected to the detection coil 21B.

At time T0, the frequency data A and the frequency data B are the minimum values because the hand is not close to the metal detection unit 20. Next, since the position of the hand is in the state B between the time T0 and the time T1, the frequency data A and the frequency data B increase substantially at the same time. Next, when the position of the hand returns to the state A between the time T1 and the time T2, the frequency data A and the frequency data B decrease substantially at the same time, and the frequency data A and the frequency data B are the minimum values at the time T2. Return to.

Further, the dotted line Th is a threshold value (determination threshold value Th) for determining whether or not the staple and the detection coil 21A are close to each other. The metal detection unit 20 of the present embodiment determines that the staple has approached the detection coil 21A when the frequency data A indicating the amount of change in the resonance frequency of the resonance circuit 22A becomes the determination threshold Th or more by the metal detection determination process. To do. Further, the determination threshold value Th changes as shown by the dotted line Th shown in FIG. 5A according to the frequency data B by the determination threshold value change process.

Next, changes in frequency data when the sheet closed by the staple S is conveyed in the state A of the hand will be described with reference to FIGS. 6 (a) and 6 (b). 6 (a) and 6 (b) are graphs showing the correspondence between the position of the staple S for binding the sheet and the frequency data. The time B0, B1 and B2 displayed on the horizontal axis of the graphs of FIGS. 6A and 6B have staples S at the positions of the dotted lines B0, B1 and B2 shown in FIGS. 4A and 4B, respectively. Corresponds to the reached state. Further, FIG. 6A shows a change in the frequency data A, and FIG. 6B shows a change in the frequency data B.

First, the change of the frequency data A will be described with reference to FIG. 6A. Since the staple S is on the feed tray 1 at the time B0, the frequency data A remains at the minimum value. Electromagnetic induction between the staple S and the detection coil 21A is between the time B1 and B2 from when the staple S reaches directly under the detection coil 21A to when the sheet bound by the staple S is conveyed. As a result, the value of the frequency data A increases. After the time B2 after the staple S has passed through the detection coil 21A, the frequency data A returns to the minimum value because there is no conductor around the detection coil 21A. The dotted line Th in FIG. 6 (a) does not change unlike that in FIG. 5 (a). This is because the frequency data B maintains the minimum value as shown in FIG. 6B when the hand does not approach the metal detection unit 20. Therefore, the determination threshold value Th indicated by the dotted line Th does not change due to the determination threshold value change process, and is constant at the same value as the preset determination threshold value Th0.

Next, changes in frequency data when the hand approaches the metal detection unit 20 at the timing when the sheet bound by the staple S is conveyed will be described with reference to FIGS. 7A and 7B. As shown in FIG. 7A, the frequency data at the times T0, B0, B1, B2, T1, and T2 shows the change in the frequency data A when the position of the hand moves in the order of state A, state B, and state A. It changes in a form in which FIG. 5 (a) described above and FIG. 6 (a) showing the correspondence between the position of the staple S for binding the sheet and the frequency data A are added. Since the change of the frequency data A at each time in FIG. 7A has the same characteristics as those in FIGS. 5A and 6A, detailed description thereof will be omitted. Since the change in the frequency data B at each time in FIG. 7 (b) has the same characteristics as in FIG. 5 (b), detailed description thereof will be omitted.

Further, between the times T0 and T1 in FIG. 7A, the determination threshold Th changes from the determination threshold Th0 due to the movement of the hand position, and the staple S approaches the detection coil 21A from the times B1 to B2. , The frequency data A exceeds the determination threshold Th. When the frequency data A exceeds the determination threshold value Th, the control unit 15 stops the transfer of the sheet, assuming that the staple S is detected.

[Difference in resonance frequency when hands approach]
Here, a processing method will be described when there is a difference between the frequency data A and the frequency data B when the hands approach each other. In the configuration of FIG. 1, when a hand approaches the feeding port E, which is intermediate between the detection coil 21A and the detection coil 21B, the frequency data A and the frequency data B change as shown in FIGS. 5A and 5B. The amounts are about the same. However, when the hand is close to the detection coil 21B and close to a position far from the detection coil 21A, the amount of change in the frequency data A becomes small as shown in FIG. 8A, and the frequency is changed as shown in FIG. 8B. The amount of change in data B becomes large. When the determination threshold value change process is executed in such a state, as shown in FIG. 8A, the frequency data A changes in the section between the times B1 and B2 when the staple S passes near the detection coil 21A. The determination threshold Th becomes larger than the amount.

In order to prevent the above situation, the control unit 15 of the present embodiment multiplies the frequency data A and then compares it with the determination threshold value Th as follows. First, the control unit 15 has a division circuit 25, a multiplication circuit 26, an addition circuit 27, and a comparison circuit 28 (see FIG. 2). The division circuit 25 acquires the data at the timing when there is no sheet directly under the detection coil 21A, that is, after the sheet detection sensor 10a detects the rear end of the sheet and before the feeding roller 17 starts conveying the sheet (between papers). This is a circuit for obtaining a coefficient M such that (frequency data A) × M = (frequency data B) from the obtained frequency data A and frequency data B by division. The multiplication circuit 26 is a circuit that multiplies the frequency data A based on the value of the coefficient M. The addition circuit 27 is a circuit that adds the determination threshold value Th and the frequency data B. The comparison circuit 28 is a circuit that compares the determination threshold value Th with the frequency data A. The control unit 15 uses these circuits to perform the metal determination process and the threshold value determination process, which will be described later.

The control unit 15 compares the frequency data A multiplied by the multiplication circuit 26 with the determination threshold Th changed based on the frequency data B based on the coefficient M (division result) calculated by the division circuit 25 in the comparison circuit 28. To do. When the frequency data A is changed (multiplied here) based on the coefficient M, the frequency data A in FIG. 8 (a) is in the same state as in FIG. 7 (a), so that the determination threshold Th is changed (multiplication). Staple S can be detected based on the comparison of the frequency data A of (later). By processing in this way, even if there is a difference between the frequency data A and the frequency data B when the hands approach each other, the staples can be detected with high accuracy. Even if the frequency data A is larger, it can be processed in the same manner by the same configuration of the control unit 15.

[Control method of metal detection unit 20 and determination method of presence / absence of staples]
Next, a control method of the metal detection unit 20 and a metal determination process including a determination threshold value change process for detecting the presence or absence of staples approaching the vicinity of the metal detection unit 20 will be described with reference to FIG. FIG. 9 is a flowchart showing control by the control unit 15 after the sheet transport device 101 raises the feed tray 1 after being instructed to start reading the sheet and the sheet reaches a position where it can be transported by the feeding roller 17. Is. Further, in the present embodiment, it is assumed that the image reading unit 40 reads the image of the sheet that has passed through the sheet sensor 43 before reading, and in FIG. 9, which shows the transfer of the sheet and the control of the metal detection unit 20, the image reading procedure will be described. Omit.

First, the control unit 15 starts driving the feed motor 13, the separation motor 14, and the transfer motor 39. As a result, the separate feeding mechanism 10, the pair of transport rollers 31, 32, and the pair of transport rollers 33, 34 are driven to separate and feed the sheet on the feed tray 1 (S101).

The metal detection unit 20 may be driven at the same time as or before S101 to start acquisition of frequency data A and frequency data B. Actually, it is preferable to start driving the metal detection unit 20 when an instruction to start image reading in the image reading device is given, for example, when the start button provided in the image reading device is pressed or connected to the image reading device. The metal detection unit 20 may be driven when a reading start instruction is input to the control unit 15 from the information processing device.

Next, the control unit 15 acquires frequency data A and frequency data B output by the frequency calculator 23A and the frequency calculator 23B, respectively (S102). In the present embodiment, the number of frequency data acquired in S102 is the same as the number of mask sizes set in the averaging filter circuit 24 of the control unit 15. Further, the control unit 15 executes an averaging process for calculating by inputting the average value of the plurality of frequency data acquired in S102 into the averaging filter circuits 24A and 24B, respectively, and the frequency data after averaging is used in the subsequent processing. use. Not limited to this embodiment, it is desirable to change the number of frequency data acquired in S102 according to the mask size of the averaging filter circuits 24A and 24B.

Here, a plurality of frequency data samples output by the frequency calculators 23A and 23B are acquired, and the average value is calculated for each. Then, the average values of the respective values are taken into the control unit 15 as frequency data A and B. In the present embodiment, the control unit 15 acquires the frequency data A and B at the same time, but may alternately acquire the frequency data A and B. The frequency data sampling time (sampling time required to calculate the frequency once) is determined by the register value inside the frequency calculators 23A and 23B, and the register value can be changed by communication from the outside. ..

After acquiring the two frequency data, the control unit 15 determines whether or not there is a sheet between the feeding roller 17 and the sheet detection sensor 10a based on the detection state of the sheet detection sensor 10a and the driving state of the feeding roller 17. (S103). Specifically, in the determination of S103, at the time of starting S103, the control unit 15 determines whether or not the sheet detection sensor 10a detects the rear end of the sheet and the feeding roller 17 starts conveying the sheet. ..

When the sheet detection sensor 10a detects the rear end of the sheet and the feeding roller 17 does not start the transfer of the sheet, that is, directly under the detection coil 21A (the range overlapping the detection coil 21A when viewed from the thickness direction of the sheet). When there is no sheet (Y in S103), the control unit 15 obtains the coefficient M obtained by calculating (frequency data B) / (frequency data A) by the division circuit 25 (S104). In the present embodiment, the initial value of the coefficient M is assumed to be 1, but the present invention is not limited to this.

Next, the control unit 15 multiplies the coefficient M by the frequency data A by the multiplication circuit 26, and multiplies the frequency data A (S105). In the following description, the frequency data A after multiplication in S105 will be referred to as frequency data A'.

On the other hand, when the sheet detection sensor 10a does not detect the rear end of the sheet in S103, or when the feeding roller 17 has started to convey the sheet, that is, when the sheet is directly under the detection coil 21A (N in S103). ), S105 is executed without executing the process of S104.

Next, the control unit 15 adds the frequency data B acquired from the frequency calculator 23B by the addition circuit 27 to the preset determination threshold value Th0, and calculates the determination threshold value Th (S106). That is, the control unit 15 changes the determination threshold value Th0 based on the frequency data B as the second detection value corresponding to the change in the magnetic field of the detection coil 21B. The details of the determination threshold value Th0 set in advance in the control unit 15 will be described later. In the following description, the determination threshold value Th0 after adding the frequency data B in S106 is described as the determination threshold value Th.

Next, the control unit 15 determines whether or not the frequency data A'is equal to or greater than the determination threshold value Th (S107). When the frequency data A'is equal to or higher than the determination threshold value Th (Y in S107), the control unit 15 instructs the feed motor 13, the separation motor 14, and the transfer motor 39 to stop driving, and separates and feeds the sheet. Is terminated (S108). That is, the control unit 15 determines whether the metal detection unit 20 has detected staples that are metal from the frequency data A'as the first detection value corresponding to the amount of change in the magnetic field of the detection coil 21A and the determination threshold value Th. .. Then, when the frequency data A'is equal to or higher than the determination threshold value Th (or higher than the threshold value), the feed motor 13, the separation motor 14, and the transfer motor 39 are stopped.

By the processing of S107 and S108, the sheet transport device 101 of the present embodiment can stop the separate feeding of the sheet when the staple approaches the detection coil 21A and the frequency data A'changes, so that the sheet bound with the staple is used. Can be prevented from being damaged. More specifically, since the staple S can be detected before the sheet rushes into the nip portion N, it is possible to prevent damage that occurs when the documents bound by the staple S are forcibly separated.

On the other hand, when the frequency data A'calculated by the frequency calculator 23A is smaller than the threshold value Th (N in S107), the sheet loading detection sensor 51 determines whether or not there is a sheet in the feed tray 1 (S109). When there is a sheet on the feeding tray 1 (N in S109), it can be determined that the bundle of sheets on the feeding tray 1 is being fed one by one, so that the control unit 15 processes from S102 again. To execute. On the other hand, when there is no sheet on the feeding tray 1 (Y in S109), it can be determined that there is no sheet to be fed on the feeding tray 1, so that the control unit 15 ends the separate feeding of the sheets (S108). ).

By processing as described above, even if a hand approaches the feeding port E (metal detection unit 20) during feeding of the sheet, false detection is not performed, and the determination threshold value and frequency data changed based on the frequency data B are not detected. By comparing with A, only the staples that bind the sheet with high accuracy can be detected. The present invention is not limited to this, and only staples that bind sheets with high accuracy can be detected based on frequency data A and frequency data B.

That is, based on the detection results (calculation results) of the frequency calculators 23A and 23B, the control unit 15 has the feed motor 13, the separation motor 14, and the transfer motor 39 (hereinafter, feed motor 13 and the like) as follows. Control the drive of. First, when a sheet bound by a metal binding member (for example, staples) is conveyed from the feeding port E, if the binding member is in the detection region of the detection coil 21B, the feed motor 13 or the like is still driven. And.

Here, the detection region of the detection coil 21B is a space in which the resonance frequency calculated by the frequency calculator 23B fluctuates when a hand approaches the vicinity of the detection coil 21B. When the sheet bound by the binding member is conveyed from the feeding port E, the feeding motor 13 or the like is driven when the binding member is at a position overlapping the detection coil 21B when viewed from the thickness direction of the sheet. You can leave it as it is.

Further, the control unit 15 stops driving the feed motor 13 and the like when the sheet bound by the binding member is conveyed from the feed port E and the binding member is in the detection region of the detection coil 21A. To. When the binding member is at a position where it overlaps with the detection coil 21A when viewed from the thickness direction of the sheet, the drive of the feed motor 13 or the like may be stopped.

On the other hand, when the control unit 15 conveys a sheet that is not bound by the binding member from the feeding port E, the control coil 21B detects a conductor such as a hand when the sheet passes through the detection region of the detection coil 21A. Even if it is arranged in the detection area of, the feed motor 13 and the like are still driven. Even if a conductor such as a hand is placed at a position where it overlaps with the detection coil 21B when viewed from the thickness direction of the sheet when the sheet passes through a position where the sheet overlaps with the detection coil 21A when viewed from the thickness direction of the sheet. , The feeding motor 13 and the like may be left driven. Further, the conductor such as a hand is a conductor that affects the magnetic field around the detection coil 21A and the detection coil 21B rather than the binding member.

Here, a method for calculating the coefficient M that can suppress the momentary fluctuation of the coefficient M due to the momentary fluctuation of the frequency data A and the frequency data B will be described. FIG. 10 is a flowchart illustrating a metal detection method capable of detecting staples even when there is a difference between frequency data A and frequency data B when a hand approaches the metal detection unit 20. In the same process as in FIG. 9, the same reference numerals are used, and detailed description thereof will be omitted.

After the processing of S102 for acquiring the frequency data, the control unit 15 determines whether or not there is a sheet between the feeding roller 17 and the sheet detection sensor 10a based on the detection state of the sheet detection sensor 10a and the driving state of the feeding roller 17. Judgment (S201). Specifically, if the sheet detection sensor 10a detects the rear end of the sheet at the start of S201 and the feeding roller 17 starts conveying the sheet, the control unit 15 has the sheet directly under the detection coil 21A. Is determined.

Note that S201 is not limited to this embodiment, and for example, it may be determined whether or not there is a sheet directly under the detection coil 21A based on the state of the sheet detection sensors provided before and after the detection coil 21A.

When the sheet detection sensor 10a detects the rear end of the sheet and the feeding roller 17 has not started to convey the sheet, that is, directly under the detection coil 21A (the range overlapping the detection coil 21A when viewed from the thickness direction of the sheet). When there is no sheet (Y in S201), the control unit 15 calculates (frequency data B) / (frequency data A) to obtain the coefficient M (S202). Next, the control unit 15 stores the coefficient M calculated in S202 in a memory (not shown) in the control unit 15 (S203).

After S203, the loop processing of S201 to S203 (hereinafter referred to as loop processing) is executed until the feeding roller 17 starts conveying the sheet.

When the feeding roller 17 starts the transfer of the sheet, that is, when the sheet is directly under the detection coil 21A (N in S201), the control unit 15 determines whether or not the loop processing is executed (S204). When the loop processing is executed (Y in S204), the control unit 15 calculates the average value of all the coefficients M stored in the memory in the loop processing (S205). After the processing of S205, the control unit 15 multiplies the frequency data A by the coefficient M (S206). In the following description, the frequency data A obtained after multiplication in S206 will be referred to as frequency data A'.

After the processing of S206, the control unit 15 starts the processing from S103 of FIG. 9, and performs the same processing thereafter. On the other hand, when the loop processing is not executed (N in S204), the control unit 15 executes S206 without executing the processing in S205.

In the processing of S205, the coefficient M stored in the memory after the calculation of the average value may be cleared in preparation for the next loop processing, or the average value of the coefficient M for the purpose of improving the accuracy of the coefficient M. Alternatively, the saved value may be retained.

By multiplying the coefficient M calculated in this way with the frequency data A, staples can be detected accurately even if the coefficient M has a momentary fluctuation.

[Judgment threshold]
Here, in the process of S106, the details of the determination threshold value Th0 set in advance in the control unit 15 will be described. The determination threshold Th0, which is a reference for detecting the change in frequency in S106, is the maximum change in frequency data A indicated when the staple binding the sheet passes near the detection coil 21A in a state where the hand does not approach the feeding port E. It is a value of about 90% of the amount. Therefore, if the change in the frequency data A is equal to or greater than the determination threshold Th0 in a state where the hand does not approach the feeding port E, it is determined that there is a staple, and if the change in the acquired frequency data is less than the determination threshold Th0. Judge that there is no staple.

The threshold value set in advance for determining the presence or absence of staples may be a value smaller than the Th0 value, for example, a predetermined ratio to the maximum value such as 50% or 70% of the maximum value. That is, the threshold value for determining that the frequency data A has been changed by the staples may be equal to or less than the difference value of the resonance frequencies between the case where there is no staple passing through the detection region of the detection coil 21A and the case where there is a staple. By setting such a threshold value in the control unit 15 in advance, the control unit 15 determines the presence or absence of staples approaching the vicinity of the detection coil 21.

As described above, in the case of the present embodiment, the detection coils 21A and 21B are arranged in the vicinity of the feeding port E, and the detection coils 21B are arranged on the upstream side in the sheet transport direction with respect to the detection coil 21A. Then, from the frequency data B of the detection coil 21B, a preset determination threshold Th0 for detecting a metal binding member such as a staple is dynamically changed based on the frequency data B to change a conductor such as a hand. Even if it is brought close to the feeding port E, erroneous detection of the binding member can be suppressed.

In the present embodiment described above, an example has been described in which the time for changing the determination threshold value Th by the frequency data A and the frequency data B is the same time, but in reality, when the hands are brought closer, the time is first. Timing adjustment (offset on the time axis) may be performed in consideration of a time difference in approaching the detection coil 21A after approaching the vicinity of the detection coil 21B.

<Other embodiments>
In the above description, as shown in FIG. 2A, resonance circuits 22A and 22B and frequency calculators 23A and 23B are provided for the detection coils 21A and 21B, respectively. With this configuration, the control unit 15 can simultaneously capture the resonance frequencies calculated by the frequency calculators 23A and 23B, respectively. However, the frequency calculator may be shared with the detection coils 21A and 21B.

That is, as shown in FIG. 11, the metal detection unit 20A of the first example of the other embodiment includes detection coils 21A and 21B, resonance circuits 22A and 22B, and a frequency calculator 23C. The detection coils 21A and 21B and the resonance circuits 22A and 22B are the same as those in the above-described embodiment. On the other hand, the frequency calculator 23C as the detection means and the frequency calculation means alternately calculates the resonance frequency of the resonance circuit 22A and the resonance frequency of the resonance circuit 22B. That is, the frequency data A and the frequency data B are alternately calculated by one frequency calculator 23C. When a plurality of frequency data are calculated by one frequency calculator in this way, the metal detection unit 20A can be configured on a smaller scale as compared with the above-described embodiment. The resonance frequency calculated by the frequency calculator 23C may be alternately taken in or used by the control unit 15, or the frequency calculator 23C may alternately calculate the resonance frequency and output it to the control unit 15. It may be configured as follows. The frequency calculator 23C in this case has a switching means for switching which of the resonance circuits 22A and 22B is connected. As the switching means, a switching element such as a relay or a transistor can be applied.

The present invention can also be applied to a configuration in which the detection coil is of one type, that is, a configuration in which the above-mentioned detection coil 21B is omitted. As shown in FIGS. 12A and 12B, the metal detection unit 20B of the second example of another embodiment includes a detection coil 21C, resonance circuits 22A and 22B, a frequency calculator 23D, and a switching unit as a switching means. Has 29.

The detection coil 21C is arranged in the vicinity of the feeding port E, similarly to the detection coil 21A of the above-described embodiment. That is, as shown in FIG. 12A, the detection coil 21C is on the upstream side (see FIG. 1) of the center (dotted line D) of the nip portion N in the sheet transport direction, and is the first guide portion of the upper transport guide 91. It is arranged on the downstream side of the dotted line C indicating the boundary between the 91a and the second guide portion 91b.

Further, the resonance circuits 22A and 22B are the same as those in the above-described embodiment, the resonance circuit 22A resonates the detection coil 21C at the first resonance frequency, and the resonance circuit 22B causes the detection coil 21C to resonate at the first resonance frequency. Resonate at the second resonance frequency. The first resonance frequency is a frequency having high sensitivity to a metal binding member such as a staple, as in the above-described embodiment, and is, for example, about 300 kHz to 500 kHz. The second resonance frequency is a frequency having low sensitivity to a metal binding member such as a staple, and is, for example, 1 MHz or more.

The switching unit 29 switches whether the detection coil 21C is resonated by the resonance circuit 22A or the resonance circuit 22B. The frequency calculator 23D calculates the first resonance frequency of the resonance circuit 22A or the second resonance frequency of the resonance circuit 22B resonated by the switching unit 29. The metal detection unit 20B configured in this way can detect metals such as staples based on the amount of change in the first resonance frequency.

For example, the switching unit 29 switches the resonance circuits 22A and 22B that resonate the detection coil 21C so that the detection coil 21C resonates alternately at the first resonance frequency and the second resonance frequency. At this time, the frequency calculator 23D calculates the resonance frequency of the resonance circuit switched by the switching unit 29. Here, the resonance frequency of the resonance circuit 22A and the resonance frequency of the resonance circuit 22B are calculated alternately.

In the case of this example as well, as in the above-described embodiment, the control unit 15 sets the first detection value (frequency data A') and the threshold value (determination threshold Th) corresponding to the amount of change in the first resonance frequency. It is determined from the above whether the metal detection unit 20B has detected the metal. At the same time, the control unit 15 changes the threshold value based on the second detection value (frequency data B) corresponding to the amount of change in the second resonance frequency. The control in this regard is the same as in the above-described embodiment.

In the case of this example, the control unit 15 bases the detection result (calculation result) of the frequency calculator 23D on the feed motor 13, the separation motor 14, the transfer motor 39 (hereinafter, the feed motor 13 and the like) as follows. ) Is controlled. First, a sheet bound by a metal binding member (for example, staples) is conveyed from the feeding port E, and when the binding member is at a position overlapping the detection region of the detection coil 21C, the resonance circuit 22B connects the detection coil 21C. When resonating, the feeding motor 13 and the like are kept driven.

In this case, the detection region of the detection coil 21C is a space in which the resonance frequency calculated by the frequency calculator 23D fluctuates when a metal binding member is passed in the vicinity of the detection coil 21C. When the sheet bound by the binding member is conveyed from the feeding port E in a state where the detection coil 21C is resonating in the resonance circuit 22B, the binding member is referred to as the detection coil 21C when viewed from the thickness direction of the sheet. When they are in the overlapping positions, it is preferable to switch the detection coil 21C so as to resonate with the resonance circuit 22A while the feed motor 13 and the like are still being driven.

Further, the control unit 15 conveys the sheet bound by the binding member from the feeding port E, and when the binding member is at a position overlapping the detection region of the detection coil 21C, the resonance circuit 22A resonates the detection coil 21C. If so, the drive of the feed motor 13 and the like is stopped. In this case, if the binding member is at a position where it overlaps with the detection coil 21C when viewed from the thickness direction of the sheet, the drive of the feed motor 13 or the like may be stopped.

On the other hand, when the control unit 15 conveys a sheet that is not bound by the binding member from the feeding port E, the control unit 15 holds a conductor such as a hand when the sheet passes through a position overlapping the detection region of the detection coil 21C. Even if the detection coil 21C is resonated by the resonance circuit 22A and arranged in the detection region of the detection coil 21C, the feed motor 13 and the like are still driven. In this case, when the sheet passes through the position where it overlaps with the detection coil 21C when viewed from the thickness direction of the sheet, the conductor such as a hand is placed at the position where it overlaps with the detection coil 21C when viewed from the thickness direction of the sheet. Even if it is arranged, the feed motor 13 and the like are kept driven, and the feed motor 13 and the like are stopped when the resonance frequency does not change when the detection coil 21C is switched to resonate with the resonance circuit 22B. You may try to do it. Further, a conductor such as a hand is a conductor that affects the magnetic field around the detection coil 21C rather than the binding member. In the case of such an example, as in the above-described embodiment, even if the detection coil 21B for detecting the conductor such as a hand is not provided, false detection is not performed when the conductor is brought close to the feeding port, and the accuracy is correct. It can detect binding members such as staples that bind sheets well.

In the above-described embodiment, the present invention is applied to the sheet transport device of the image reading device, but the sheet transport device according to the present invention forms an image on, for example, a sheet transported by the sheet transport device in addition to the image reading device. It can also be applied to an image forming apparatus having an image forming portion. Further, for example, the present invention can be applied to an automatic document reader (ADF) provided in an image forming apparatus.

Further, in the above-described embodiment, the configuration in which the separation roller is used as the separation member of the separation feeding mechanism has been described, but the separation member may be a belt other than the roller, and the friction coefficient with the sheet may be high. The friction member may be larger than the transport guide of the transport path. Further, the feeding rotating body may be a belt other than the roller.

Further, in the above-described embodiment, the detection coils 21A, 21B, and 21C are arranged on the upper transfer guide 91, but may be arranged on the lower transfer guide 92. Also in this case, the arrangement of the detection coil in the sheet transport direction and the width direction intersecting the sheet transport directions is set in the vicinity of the supply port E as in the case of providing the upper transport guide 91. Further, one of the detection coils 21A and 21B (for example, the detection coil 21B) is arranged on the upper transfer guide 91 side, and the other detection coil (for example, the detection coil 21A) is arranged on the lower transfer guide 92 side. Is also good.

1 ... Feed tray / 10 ... Separation feed mechanism / 11 ... Feed roller (feed means) / 12 ... Separation roller (separation member) / 13 ... Feed motor (drive) Means) / 15 ... Control unit (control means) / 17 ... Feeding roller (feeding means) / 20, 20A, 20B ... Metal detection unit (metal detecting means) / 21A, 21B, 21C ... Detection coil / 22A, 22B ... Resonant circuit (magnetic field generation circuit) / 23A, 23B, 23C, 23D ... Frequency calculator (detection means, frequency calculation means) / 40 ... Image reader / 100 ...・ Image reader / 101 ・ ・ ・ Sheet transfer device

Claims (16)

A feeding means for feeding the sheet from the feeding port into the device, and
The first detection coil arranged in the vicinity of the feed port on the downstream side in the sheet transport direction and the first detection coil arranged in the vicinity of the feed port and on the upstream side in the sheet transport direction with respect to the first detection coil. A second detection coil, a magnetic field generation circuit that excites the first detection coil and the second detection coil to generate a magnetic field, and magnetic fields of the first detection coil and the second detection coil, respectively. A metal detecting means having a detecting means for detecting the amount of change in the above means, and a metal detecting means capable of detecting a metal based on the detection result of the detecting means.
From the first detection value and the threshold value corresponding to the change amount of the magnetic field of the first detection coil, it is determined whether the metal detecting means has detected the metal, and the change amount of the magnetic field of the second detection coil is dealt with. A control means for changing the threshold value based on the second detected value is provided.
A sheet transfer device characterized by this. A driving means for driving the feeding means is provided.
The control means stops driving the driving means when the first detection value is equal to or higher than the threshold value.
The sheet transport device according to claim 1, wherein the sheet transport device is characterized by the above. The control means divides between the first detected value and the second detected value, changes the first detected value based on the division result, and sets the changed first detected value and the threshold value. To determine whether the metal detecting means has detected metal,
The sheet transport device according to claim 1 or 2, wherein the sheet transport device is characterized by the above. The control means obtains the second detection value rather than the number of samples corresponding to the amount of change in the magnetic field of the first detection coil in order for the control means to obtain the first detection value. The number of samples corresponding to the amount of change in the magnetic field of the detection coil of 2 is larger.
The sheet transport device according to any one of claims 1 to 3, wherein the sheet transport device is characterized by the above. A feeding means for feeding the sheet from the feeding port into the device, and
The driving means for driving the feeding means and
A first detection coil arranged in the vicinity of the feed port on the downstream side in the sheet transport direction, and
A second detection coil arranged in the vicinity of the feeding port and on the upstream side in the sheet transport direction with respect to the first detection coil.
A magnetic field generation circuit that excites the first detection coil and the second detection coil to generate a magnetic field.
A detection means for detecting the amount of change in the magnetic field of each of the first detection coil and the second detection coil, and
When the sheet bound by the metal binding member is conveyed from the feeding port based on the detection result of the detection means, the binding member is in the detection region of the second detection coil. The driving means is kept driven, and when the binding member is in the detection region of the first detection coil, the driving of the driving means is stopped, and the binding member is bound from the feeding port by the binding member. When the sheet is conveyed, the first detection coil and the first detection coil are more than the binding member when the sheet passes through the detection region of the first detection coil based on the detection result of the detection means. Control that controls the drive means so that the drive means remains driven even if a conductor that affects the magnetic field around the second detection coil is arranged in the detection region of the second detection coil. With means,
A sheet transfer device characterized by this. The second detection coil is arranged on the upstream side in the sheet transport direction with respect to the supply port.
The sheet transport device according to any one of claims 1 to 5, wherein the sheet transport device is characterized by the above. The distance from the feeding port to the first detection coil and the distance from the feeding port to the second detection coil are substantially the same.
The sheet transport device according to claim 6, wherein the sheet transport device is characterized by the above. The first detection coil and the second detection coil are flat coils.
The second detection coil is arranged at a position off the same plane as the first detection coil.
The sheet transport device according to any one of claims 1 to 7, wherein the sheet transport device is characterized by the above. The second detection coil is arranged at an angle with respect to the first detection coil.
The sheet transport device according to claim 8, wherein the sheet transport device is characterized by this. The second detection coil is arranged at a position where the distance from the feed port to the sheet conveyed is farther than that of the first detection coil.
The sheet transport device according to any one of claims 1 to 9, wherein the sheet transport device is characterized by the above. The magnetic field generation circuit includes a first resonance circuit that resonates the first detection coil and a second resonance circuit that resonates the second detection coil.
The detecting means includes a first frequency calculating means for calculating the resonance frequency of the first resonance circuit and a second frequency calculating means for calculating the resonance frequency of the second resonance circuit.
The sheet transport device according to any one of claims 1 to 10, wherein the sheet transport device is characterized by the above. The magnetic field generation circuit includes a first resonance circuit that resonates the first detection coil and a second resonance circuit that resonates the second detection coil.
The detecting means includes a frequency calculating means for alternately calculating the resonance frequency of the first resonance circuit and the resonance frequency of the second resonance circuit.
The sheet transport device according to any one of claims 1 to 10, wherein the sheet transport device is characterized by the above. A feeding means for feeding the sheet from the feeding port into the device, and
The detection coil arranged in the vicinity of the feeding port, the first resonance circuit that resonates the detection coil at the first resonance frequency, and the detection coil are resonated at a second resonance frequency different from the first resonance frequency. A second resonance circuit, a switching means for switching whether the detection coil is resonated with the first resonance circuit or the second resonance circuit, and the first switching means resonating with the switching means. A metal detecting means that has a frequency calculating means for calculating the first resonance frequency of the resonance circuit or the second resonance frequency of the second resonance circuit, and can detect metal based on the amount of change in the first resonance frequency. When,
From the first detection value and the threshold value corresponding to the change amount of the first resonance frequency, it is determined whether the metal detecting means has detected the metal, and the second detection value corresponding to the change amount of the second resonance frequency is obtained. A control means for changing the threshold value based on the above.
A sheet transfer device characterized by this. A feeding means for feeding the sheet from the feeding port into the device, and
The driving means for driving the feeding means and
A detection coil arranged in the vicinity of the feeding port and
A first resonance circuit that resonates the detection coil at the first resonance frequency,
A second resonance circuit that resonates the detection coil at a second resonance frequency different from the first resonance frequency,
A switching means for switching between resonating the detection coil in the first resonance circuit and resonance in the second resonance circuit.
A frequency calculating means for calculating the resonance frequency of the first resonance circuit or the resonance frequency of the second resonance circuit resonated by the switching means.
A sheet bound by a metal binding member is conveyed from the feeding port, and when the binding member is at a position overlapping the detection region of the detection coil, the detection coil is resonated by the first resonance circuit. When the sheet is stopped, the driving of the driving means is stopped based on the calculation result by the frequency calculating means, and the sheet not bound by the binding member is conveyed from the feeding port. Resonates the detection coil with the first resonance circuit with a conductor that affects the magnetic field around the detection coil rather than the binding member when is passing through a position overlapping the detection region of the detection coil. A control means for controlling the drive means is provided so that the drive means remains driven even if the drive means is arranged in the detection region of the detection coil in the state of being in the state.
A sheet transfer device characterized by this. The resonance frequency of the second resonant circuit is higher than the resonant frequency of the first resonant circuit.
The sheet transport device according to any one of claims 11 to 14, wherein the sheet transport device is characterized by the above. The sheet transfer device according to any one of claims 1 to 15.
An image reading unit for reading an image of a sheet conveyed by the sheet conveying device is provided.
An image reader characterized by this.

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