Patent Publication Number: US-2023138589-A1

Title: Conductive sheet and sheet bundle package

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2021-178653, filed on Nov. 1, 2021, the entire contents of which are incorporated herein by reference. 
     FIELD 
     Embodiments described herein relate generally to a conductive sheet and a sheet bundle package. 
     BACKGROUND 
     An image forming device that forms an image on a sheet is used. There is a sheet having a wireless tag from and to which information is read and written. Reading and writing may be erroneously executed on the sheet that is not a target of reading and writing. It is required to prevent erroneous reading and writing. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is an explanatory view illustrating an example of a configuration of an image forming device; 
         FIG.  2    is a hardware configuration diagram of the image forming device of  FIG.  1   ; 
         FIG.  3    is a perspective view of a paper feed cassette of the image forming device of  FIG.  1   ; 
         FIG.  4    is a first explanatory view of an operation of a paper feed mechanism of the image forming device of  FIG.  1   ; 
         FIG.  5    is a second explanatory view of the operation of the paper feed mechanism of the image forming device of  FIG.  1   ; 
         FIG.  6    is a first explanatory view of an operation of an empty sensor of the image forming device of  FIG.  1   ; 
         FIG.  7    is a second explanatory view of the empty sensor of the image forming device of  FIG.  1   ; 
         FIG.  8    is a perspective view of a sheet bundle package; 
         FIG.  9    is a perspective view of an inclusion of the sheet bundle package of  FIG.  8   ; 
         FIG.  10    is a plan view of a conductive sheet of the inclusion of  FIG.  9    according to a first embodiment; 
         FIG.  11    is a plan view of a state of the conductive sheet of  FIG.  10    being mounted on a sheet placing portion; 
         FIG.  12    is a plan view of a conductive sheet according to a first modification of the first embodiment of  FIG.  10   ; 
         FIG.  13    is a bottom view of a conductive sheet according to a second modification of the first embodiment of  FIG.  10   ; 
         FIG.  14    is a bottom view of a conductive sheet according to a third modification of the first embodiment of  FIG.  10   ; 
         FIG.  15    is a plan view of a conductive sheet of the inclusion of  FIG.  9    according to a second embodiment; 
         FIG.  16    is a plan view of a conductive sheet of the inclusion of  FIG.  9    according to a third embodiment; 
         FIG.  17    is a plan view of a state of the conductive sheet of  FIG.  16    being mounted on a sheet placing portion; 
         FIG.  18    is a plan view of a conductive sheet of the inclusion of  FIG.  9    according to a fourth embodiment; 
         FIG.  19    is a cross-sectional view taken along a line P-P of the conductive sheet in  FIG.  18   ; and 
         FIG.  20    is a plan view of a conductive sheet according to a first modification of the fourth embodiment of  FIG.  18   . 
     
    
    
     DETAILED DESCRIPTION 
     In general, according to one embodiment, a conductive sheet capable of preventing erroneous reading and writing is provided. 
     According to an embodiment, a conductive sheet can be provided between a sheet tray of an image forming device and a sheet. The conductive sheet has a conductivity in a region overlapping with a wireless tag of the sheet. The conductive sheet includes a double conveyance prevention structure configured to prevent conveyance in a state in which the conductive sheet overlaps the sheet. 
     Hereinafter, a conductive sheet and a sheet bundle package according to the embodiment will be described with reference to drawings. 
     First, a configuration of an image forming device  10  according to the embodiment will be described with reference to  FIG.  1   .  FIG.  1    is an explanatory view illustrating an example of the configuration of the image forming device  10 . 
     In  FIG.  1   , the image forming device  10  includes a control panel  95 , a wireless tag communication device  90  (a transceiver, a receiver, a reader, etc.), and a printer unit  20  (a printer). The printer unit  20  includes a control unit  100  (a control system, a controller, etc.), paper feed cassettes  11   a,    11   b,  and the like. The control unit  100  controls the control panel  95 , the wireless tag communication device  90 , and the printer unit  20 . The control unit  100  controls conveyance of a sheet in the printer unit  20 . The control of the conveyance of the sheet is to control a conveyance timing of the sheet, a stop position of the sheet, a conveyance speed of the sheet, and the like. 
     The control panel  95  includes an input key and a display unit (a display). For example, the input key accepts input from a user. For example, the display unit is a touch panel type. The display unit accepts input from the user and executes display to the user. For example, the control panel  95  displays an item related to an operation of the image forming device  10  on the display unit such that the item is settable. The control panel  95  notifies the control unit  100  of the item set by the user. 
     The paper feed cassettes  11   a,    11   b  contain the sheet on which a wireless tag is provided. Certainly, the paper feed cassettes  11   a,    11   b  can also contain a sheet on which no wireless tag is provided. In the following description, unless otherwise specified, the sheet is a sheet on which the wireless tag is provided. For example, a material such as paper and a plastic film is used for the sheet. 
     The printer unit  20  performs an operation of forming an image. For example, the printer unit  20  forms an image indicated by image data on the sheet. In the following description, forming the image on the sheet is also referred to as “printing”. In the present embodiment, the printer unit  20  is a device that fixes a toner image. Alternatively, the printer unit  20  is not limited to this, and may be an ink jet type device. 
     The printer unit  20  includes an intermediate transfer belt  21 . The printer unit  20  supports the intermediate transfer belt  21  with a driven roller  41 , a backup roller  40 , and the like. The printer unit  20  rotates the intermediate transfer belt  21  in a direction of an arrow m. The printer unit  20  includes four sets of image forming stations  22 Y,  22 M,  22 C, and  22 K. The image forming stations  22 Y,  22 M,  22 C, and  22 K correspond to yellow (Y), magenta (M), cyan (C), and black (K), respectively. The image forming stations  22 Y,  22 M,  22 C, and  22 K are arranged on a lower side of the intermediate transfer belt  21  along a rotation direction of the intermediate transfer belt  21 . 
     Hereinafter, among the image forming stations  22 Y,  22 M,  22 C, and  22 K, the image forming station  22 Y of the yellow (Y) will be described as an example. Since the image forming stations  22 M,  22 C, and  22 K have the same configuration as the image forming station  22 Y, a detailed description thereof will be omitted. 
     The image forming station  22 Y includes an electric charger  26 , an exposure scanning head  27 , a developing device  28 , and a photoconductor cleaner  29 . The electric charger  26 , the exposure scanning head  27 , the developing device  28 , and the photoconductor cleaner  29  are provided around a photoconductor drum  24  that rotates in a direction of an arrow n. 
     The image forming station  22 Y includes a primary transfer roller  30 . The primary transfer roller  30  faces the photoconductor drum  24  via the intermediate transfer belt  21 . 
     The electric charger  26  uniformly charges the photoconductor drum  24 . The exposure scanning head  27  exposes the uniformly charged photoconductor drum  24  to form an electrostatic latent image on the photoconductor drum  24 . The developing device  28  develops the electrostatic latent image on the photoconductor drum  24  using a two-component developer formed of a toner and a carrier. 
     The primary transfer roller  30  primary transfers the toner image formed on the photoconductor drum  24  to the intermediate transfer belt  21 . Each of the primary transfer rollers  30  of the image forming stations  22 Y,  22 M,  22 C, and  22 K primary transfers the toner image to the intermediate transfer belt  21 , so that a color toner image is formed on the intermediate transfer belt  21 . The color toner image is a toner image formed by sequentially superimposing the toner images of the yellow (Y), the magenta (M), the cyan (C), and the black (K). The photoconductor cleaner  29  removes the toner remaining on the photoconductor drum  24  after the primary transfer. 
     The printer unit  20  includes a secondary transfer roller  32 . The secondary transfer roller  32  faces the backup roller  40  via the intermediate transfer belt  21 . The secondary transfer roller  32  collectively and secondarily transfers the color toner image on the intermediate transfer belt  21  to the sheet. In the following description, the “toner image” may be either the color toner image or the toner image of only one color. In addition, the toner image may be a toner image using a decolorable toner. 
     A conveyance path  33  is a path through which the sheet is conveyed by a plurality of conveyance rollers (for example, a conveyance roller  330 ). The conveyance path  33  includes a first conveyance path  33   a,  a second conveyance path  33   b,  and a third conveyance path  33   c.  The first conveyance path  33   a  is a conveyance path from a merging portion  44   a  to a branch portion  44   b.  The second conveyance path  33   b  is a conveyance path that passes through a double-sided printing device  38 , and is a conveyance path from the branch portion  44   b  to the merging portion  44   a,  which is different from the first conveyance path  33   a.  The third conveyance path  33   c  is a conveyance path from the branch portion  44   b  to a paper discharge tray  35 . 
     The sheet is picked up from the sheet placing portion  11  of any of the paper feed cassette  11   a,  the paper feed cassette  11   b,  and a manual feed tray  11   c.  The sheet picked up from the sheet placing portion  11  is temporarily stopped at a portion where two stopped registration rollers  31  are in contact with each other. At this time, a tip of the sheet abuts against the registration rollers  31 , and inclination of the sheet is corrected. The control unit  100  starts rotation of the registration rollers  31  according to a position of the toner image on the rotating intermediate transfer belt  21  to move the sheet to a position of the secondary transfer roller  32 . 
     The toner image formed on the intermediate transfer belt  21  is secondarily transferred to the sheet by the secondary transfer roller  32 . Further, the secondary transferred toner image is fixed to the sheet by a fixing device  34 . In this way, an image is formed on the sheet by the control of the control unit  100 . The control unit  100  conveys the sheet on which the toner image is fixed by the fixing device  34  to the third conveyance path  33   c,  and discharges the sheet. 
     The wireless tag communication device  90  includes a calculation device (a calculator), a storage device (a memory), and an antenna (not shown). The wireless tag according to the present embodiment is, for example, a radio frequency identification (RFID) tag. The wireless tag communication device  90  transmits a radio wave in a direction of an arrow k, for example. The wireless tag communication device  90  communicates with the wireless tag provided on the sheet via the antenna. Specifically, the wireless tag communication device  90  reads information from the wireless tag and writes the information on the wireless tag. 
     The information written on the wireless tag includes, for example, if the sheet is used for physical distribution or the like, information indicating a content, information indicating a destination, a content printed on the sheet, and the like. According to the present embodiment, the wireless tag communication device  90  uses, for example, an ultra-high frequency (UHF) in the 860 megahertz (MHz) to 960 MHz band. However, the RFID method and the frequency band are not limited to this, and other methods and frequency bands can be adopted. 
     The control unit  100  controls each unit of the image forming device  10 . 
       FIG.  2    is a hardware configuration diagram of the image forming device  10 . The control unit  100  of the image forming device  10  includes a central processing unit (CPU)  91 , a memory  92 , an auxiliary storage device  93 , and the like that are connected by a bus, and executes a program. The image forming device  10  functions as a device including the printer unit  20 , the control panel  95 , and the wireless tag communication device  90  by executing the program. 
     The CPU  91  functions as the control unit  100  by executing the program stored in the memory  92  and the auxiliary storage device  93 . The control unit  100  controls an operation of each functional unit of the image forming device  10 . 
     The auxiliary storage device  93  is implemented using a storage device such as a magnetic hard disk device or a semiconductor storage device. The auxiliary storage device  93  stores information. 
     A paper feed unit of an image forming device will be described in detail. 
       FIG.  3    is a perspective view of paper feed cassettes. In the present application, a Z direction, an X direction, and a Y direction of an orthogonal coordinate system are defined as follows. The Z direction is a vertical direction, and a +Z direction is an upward direction. The X direction and the Y direction are horizontal directions. The X direction is a left-right direction toward the front of the image forming device  10 . A +X direction is a direction in which the sheet is conveyed from the paper feed cassettes  11   a,    11   b.  The Y direction is a front-rear direction of the image forming device  10 . A +Y direction is a direction from the front to the back toward the front of the image forming device  10 . 
     The paper feed cassettes  11   a,    11   b  contain the sheet inside. The paper feed cassettes  11   a,    11   b  are attachable to and detachable from the image forming device  10 . The paper feed cassettes  11   a,    11   b  include a cassette body  12 , a sheet tray  13 , side guides  15 , and an end guide  16 . The cassette body  12  has a drawer shape. 
     The sheet tray  13  is formed in a plate shape by a metal material or the like. The sheet tray  13  is provided on a bottom plate of the cassette body  12 . The sheet tray  13  is provided closer to the +X direction inside the cassette body  12 . The sheet tray  13  is rotatable. An end portion of the sheet tray  13  in a −X direction is a rotation axis, and an end portion of the sheet tray  13  in the +X direction moves in an upper-lower direction. The sheet is provided on the sheet tray  13 . The sheet tray  13  lifts an end portion of the sheet in the +X direction toward a pickup roller to be described later. 
     The side guides  15  are formed in a flat plate shape in which the Y direction is a thickness direction. A pair of the side guides  15  are provided apart from each other in the Y direction. The pair of side guides  15  abut against both end portions of the sheet in the Y direction. The side guides  15  regulate movement of the sheet in the Y direction. 
     An end guide  16  is formed in a flat plate shape in which the X direction is a thickness direction. The end guide  16  abuts against an end portion of the sheet in the −X direction. The end guide  16  regulates movement of the sheet in the −X direction. 
       FIG.  4    is a first explanatory view of an operation of a paper feed mechanism, and  FIG.  5    is a second explanatory view. The image forming device  10  includes a pickup roller  17 , a paper feed roller  18 , and a separation roller  19  as the paper feed mechanism. 
     The pickup roller  17  is provided above the end portion of the sheet tray  13  in the +X direction. The pickup roller  17  abuts against an upper surface of a sheet  55  placed on the sheet tray  13 . The pickup roller  17  is rotationally driven. The pickup roller  17  conveys the sheet  55  in the +X direction. 
     The paper feed roller  18  is provided on the pickup roller  17  in the +X direction. The paper feed roller  18  is rotationally driven. 
     The separation roller  19  is provided on the paper feed roller  18  in a −Z direction. The separation roller  19  is driven to rotate with the rotation of the paper feed roller  18 . The separation roller  19  includes a torque limiter. 
     The pickup roller  17  conveys the sheet  55  toward a nip of the paper feed roller  18  and the separation roller  19 . As illustrated in  FIG.  4   , when one sheet  55  is conveyed, the paper feed roller  18  and the separation roller  19  rotate together. Accordingly, the sheet  55  is conveyed downstream. 
     As illustrated in  FIG.  5   , a plurality of the sheets  55  may be overlapped and conveyed (double-conveyed) by the pickup roller  17 . The paper feed roller  18  rotates to convey the upper sheet  55  downstream. The separation roller  19  does not rotate and stops conveyance of the lower sheet. Accordingly, only the upper sheet  55  is conveyed downstream. After the upper sheet  55  is conveyed, the lower sheet  55  is conveyed downstream by the paper feed roller  18 . 
     An empty sensor  45  will be described. 
     As illustrated in  FIG.  1   , the image forming device  10  includes the empty sensor  45 . The empty sensor  45  detects the absence of the sheet  55  in the sheet placing portion  11 . 
       FIG.  6    is a first explanatory view of an operation of an empty sensor, and  FIG.  7    is a second explanatory view. The empty sensor  45  includes a light irradiation unit  46 , a shutter  47 , and a trigger  48 . The light irradiation unit  46  radiates light from a light projecting unit (a light projector) toward a light receiving unit (a light receiver). The shutter  47  can block the light of the light irradiation unit  46 . The shutter  47  is movable in conjunction with the trigger  48 . The trigger  48  can fall on a tray window portion  14  of the sheet tray  13 . The tray window portion  14  penetrates the sheet tray  13  in a thickness direction. The tray window portion  14  is used for detecting the absence of the sheet  55  by the empty sensor  45 . 
     In  FIG.  6   , the sheet  55  is present on the sheet tray  13 . The trigger  48  is supported by the sheet  55  and does not fall on the tray window portion  14 . The shutter  47  does not block the light of the light irradiation unit  46 . The empty sensor  45  does not detect the absence of the sheet. 
     In  FIG.  7   , the sheet  55  is not present on the sheet tray  13 . The trigger  48  is not supported by the sheet  55  and falls on the tray window portion  14 . The shutter  47  blocks the light of the light irradiation unit  46 . The empty sensor  45  detects the absence of the sheet. 
     First Embodiment 
     A conductive sheet and a sheet bundle package according to a first embodiment will be described in detail. 
       FIG.  8    is a perspective view of the sheet bundle package. The sheet bundle package  50  is obtained by packing an inclusion with a package material  51  such as paper.  FIG.  9    is a perspective view of the inclusion of the sheet bundle package. The sheet bundle package  50  includes a sheet bundle  59 , a conductive sheet  60 , and a seal mount  79  as the inclusions. The sheet bundle  59  is formed by stacking the plurality of sheets  55  in the Z direction. 
     The sheet  55  includes a wireless tag  57 . The wireless tag  57  is embedded inside the sheet  55 . The wireless tag  57  may be mounted on a surface of the sheet  55 . As viewed from the Z direction, the wireless tag  57  is provided on a part of the sheet  55 . For example, the wireless tag  57  is a radio frequency identification (RFID) tag. 
     A size of the conductive sheet  60  is the same as that of the sheet  55 . A thickness of the conductive sheet  60  may be the same as or different from that of the sheet  55 . A base material or layer of the conductive sheet  60  is formed of a resin material or the like. The conductive sheet  60  has a conductive region C formed of a conductive material. As viewed from the Z direction, the conductive region C overlaps the wireless tag  57  of the sheet  55 . In an example in  FIG.  6   , an entire surface of the conductive sheet  60  is the conductive region C. For example, the conductive material is a metal material such as aluminum. For example, the conductive region C is formed by vapor deposition of aluminum on the base material of the conductive sheet  60 . The base material of the conductive sheet  60  may alternatively be formed of the conductive material. 
     A sheet, that is, a target of reading and writing executed by the wireless tag communication device  90  in  FIG.  1    is a sheet moving along the conveyance path  33 . The sheet  55  set in the sheet placing portion  11  is not the target of reading and writing executed by the wireless tag communication device  90 . If the plurality of sheets  55  are present on the sheet placing portion  11 , the wireless tags  57  of the sheets  55  overlap each other in the Z direction. An impedance of an antenna of the wireless tag  57  decreases, matching with a chip that is broken, and a communication between the wireless tag  57  and the wireless tag communication device  90  becomes difficult. Accordingly, erroneous reading and writing for the plurality of sheets  55  provided on the sheet placing portion  11  is prevented. 
     When the sheet  55  on the sheet placing portion  11  is consumed for printing and the remaining sheets  55  become one sheet (i.e., all of the sheets  55  have been consumed for printing expect for one sheet), the wireless tags  57  do not overlap in the Z direction. It is necessary to prevent the erroneous reading and writing for the one sheet  55 . 
     As illustrated in  FIG.  4   , the conductive sheet  60  is provided between the sheet tray  13  and the sheet  55 . The conductive sheet  60  is present below the remaining one sheet  55 . As viewed from the Z direction, the conductive region C of the conductive sheet  60  overlaps with the wireless tag  57  of the sheet  55 . The impedance of the antenna of the wireless tag  57  decreases, and the communication between the wireless tag  57  and the wireless tag communication device  90  becomes difficult. Accordingly, the erroneous reading and writing for the remaining one sheet  55  on the sheet placing portion  11  is prevented. 
       FIG.  10    is a plan view of the conductive sheet according to the first embodiment.  FIG.  11    is a plan view of a state in which the conductive sheet according to the first embodiment is mounted on a sheet placing portion. As illustrated in  FIG.  11   , the sheet tray  13  has the tray window portion  14  described above. The tray window portion  14  is used for detecting the absence of the sheet  55 . The tray window portion  14  is provided at the end portion of the sheet tray  13  in the +X direction. 
     The conductive sheet  60  has a base layer that defines a notch  61 . The notch  61  is formed at an end portion of the conductive sheet  60  in the +X direction. As viewed from the Z direction, the notch  61  is formed at a position overlapping the tray window portion  14 . As viewed from the Z direction, at least a part of the tray window portion  14  is exposed from the notch  61 . 
     The conductive sheet  60  is provided on the sheet tray  13  of the sheet placing portion  11 , and the sheet bundle  59  is provided on the conductive sheet  60 . If all the sheets  55  of the sheet bundle  59  are consumed for printing, only the conductive sheet  60  remains on the sheet tray  13 . The trigger  48  of the empty sensor  45  illustrated in  FIG.  7    passes through the notch  61  of the conductive sheet  60  and falls to the tray window portion  14 . The empty sensor  45  detects the absence of the sheet  55 . 
     If it is detected that the sheet  55  is absent, the control unit  100  in  FIG.  1    displays the detection result on the control panel  95 . The control unit  100  stops a printing job. The conductive sheet  60  remains in the sheet placing portion  11 . The user of the image forming device  10  sets a new sheet bundle  59  on the conductive sheet  60  and restarts the printing job. When a size of the sheet  55  to be printed is changed, the user picks up the conductive sheet  60  of the old size. The user sets a conductive sheet  60  of a new size and the sheet bundle  59  of the new size and restarts the printing job. 
     If a large number of sheets  55  in the sheet bundle  59  are consumed for printing, a small number of sheets  55  and the conductive sheet  60  remain on the sheet tray  13 . As illustrated in  FIG.  5   , the pickup roller  17  may double-convey the sheet  55  and the conductive sheet  60 . The separation roller  19  stops the conveyance of the lower conductive sheet  60 . The conductive sheet  60  stops at a position of the separation roller  19 . A position of the notch  61  is separated from the tray window portion  14 , and the tray window portion  14  is covered with the conductive sheet  60 . Since the trigger  48  does not fall on the tray window portion  14 , the empty sensor  45  does not detect the absence of the sheet  55 . The printing job may continue and the conductive sheet  60  may be conveyed downstream. It is required to prevent the double conveyance of the sheet  55  and the conductive sheet  60 . 
     The conductive sheet  60  includes a double conveyance prevention structure that prevents the double conveyance with the sheet  55 . The double conveyance prevention structure according to the first embodiment regulates a relative movement of the conductive sheet  60  with respect to the sheet tray  13 . As illustrated in  FIG.  10   , the conductive sheet  60  has a seal attaching region  62  on an upper surface as the double conveyance prevention structure. The seal attaching region  62  is set along an edge side of the conductive sheet  60  in the −X direction. The seal attaching region  62  is displayed by a broken line or the like around the seal attaching region. The broken line or the like clearly indicates the position of the seal attaching region  62 . As illustrated in  FIG.  11   , a fixed seal  70  is attached to the seal attaching region  62 . 
     The fixed seal  70  has a low adhesion property on a lower surface and no adhesion property on an upper surface. The fixed seal  70  has a substantially rectangular shape in which the Y direction is a longitudinal direction and the X direction is a lateral direction. A width of the fixed seal  70  in the X direction is larger than a width of the seal attaching region  62  of the conductive sheet  60  in the X direction. About half of the fixed seal  70  in the +X direction is attached to the seal attaching region  62 . About half of the fixed seal  70  in the −X direction is attached to the sheet tray  13  or a bottom plate of the sheet placing portion  11  (hereinafter, may be referred to as the sheet tray  13  or the like). Accordingly, the relative movement of the conductive sheet  60  with respect to the sheet tray  13  is regulated. The double conveyance of the conductive sheet  60  accompanying the conveyance of the sheet  55  is prevented. 
     A notch  71  is formed at an end portion of the fixed seal  70  in the −X direction. The notch  71  avoids interference between the fixed seal  70  and the end guide  16 . 
     As described above, when the size of the sheet  55  to be printed is changed, the conductive sheet  60  of a first old size is picked up from the sheet placing portion  11 . In a state in which half of the fixed seal  70  in the +X direction is attached to the conductive sheet  60 , half of the fixed seal  70  in the −X direction is peeled from the sheet tray  13  or the like. Printing of the sheet  55  of a second size may return to printing of the sheet  55  of the first size again. At this time, in the state in which the half of the fixed seal  70  in the +X direction is attached to the conductive sheet  60 , the half of the fixed seal  70  in the −X direction is attached again to the sheet tray  13  or the like. By repeating these operations, an adhesion force of the fixed seal  70  may decrease. 
     As illustrated in  FIG.  9   , the seal mount  79  stores a plurality of the fixed seals  70 . The user picks up the fixed seals  70  one by one from the seal mount  79  and attaches the fixed seals to the conductive sheet  60 . When the adhesion force of the old fixed seal  70  decreases, the user picks up the new fixed seal  70  from the seal mount  79  and attaches the new fixed seal  70  to the conductive sheet  60 . Accordingly, the conductive sheet  60  can be reused for a long period of time. 
     An upper surface of the sheet bundle package  50  illustrated in  FIG.  8    indicates that this surface is an upper surface and that the sheet bundle package  50  is to be opened with this surface facing up. The conductive sheet  60  and the seal mount  79  are arranged on the sheet bundle  59  as the inclusions of the sheet bundle package  50  illustrated in  FIG.  9   . The user who opens the package material  51  can notice the presence of the conductive sheet  60  and the seal mount  79 . The sheet bundle package  50  includes an available manual that describes a method for using the conductive sheet  60  and the seal mount  79 . The method for using the conductive sheet  60  and the seal mount  79  may be described on the upper surface of the conductive sheet  60  or may be described on the upper surface of the sheet bundle package  50 . 
     A first modification of the first embodiment will be described. 
       FIG.  12    is a plan view of a conductive sheet according to a first modification of the first embodiment. The conductive sheet  60  according to the first modification has a base layer that defines an aperture or first window portion  63  instead of the notch  61  of the conductive sheet  60  according to the first embodiment. The description of the first modification for the portion similar to that according to the first embodiment may be omitted. 
     As viewed from the Z direction, the first window portion  63  is formed at a position overlapping the tray window portion  14 . As viewed from the Z direction, at least a part of the tray window portion  14  is exposed from the first window portion  63 . The trigger  48  of the empty sensor  45  illustrated in  FIG.  7    passes through the first window portion  63  of the conductive sheet  60  and falls to the tray window portion  14 . The empty sensor  45  detects the absence of the sheet  55 . 
     A second modification of the first embodiment will be described. 
       FIG.  13    is a bottom view of a conductive sheet according to the second modification of the first embodiment. The conductive sheet  60  according to the second modification includes a double-sided tape  64  as a double conveyance prevention structure instead of the seal attaching region  62  of the conductive sheet  60  according to the first embodiment. The description of the second modification for the portion similar to that according to the first embodiment may be omitted. 
     The double-sided tape  64  has an adhesion property on both an upper surface and a lower surface. The upper surface of the double-sided tape  64  is attached to a lower surface of the conductive sheet  60  illustrated in  FIG.  13   . The double-sided tape  64  is attached along the edge side of the conductive sheet  60  in the −X direction. The lower surface of the double-sided tape  64  is covered with a protective sheet. The user peels off the protective sheet of the double-sided tape  64  and places the conductive sheet  60  on the sheet tray  13 . The lower surface of the double-sided tape  64  is attached to the sheet tray  13 . Accordingly, the relative movement of the conductive sheet  60  with respect to the sheet tray  13  is regulated. The double conveyance of the conductive sheet  60  accompanying the conveyance of the sheet  55  is prevented. 
     A third modification of the first embodiment will be described. 
       FIG.  14    is a bottom view of a conductive sheet according to the third modification of the first embodiment. The conductive sheet  60  according to the second modification includes a resilient, high friction, or rubber sheet  65  as a double conveyance prevention structure instead of the seal attaching region  62  of the conductive sheet  60  according to the first embodiment. The description of the third modification for the portion similar to that according to the first embodiment may be omitted. 
     The rubber sheet  65  is a material having a high coefficient of friction. The rubber sheet  65  is mounted on the entire lower surface of the conductive sheet  60 . The rubber sheet  65  may be mounted on a part of the lower surface of the conductive sheet  60 . The conductive sheet  60  comes into contact with the sheet tray  13  via the rubber sheet  65 . A frictional force acting on the conductive sheet  60  from the sheet tray  13  becomes large. Accordingly, the relative movement of the conductive sheet  60  with respect to the sheet tray  13  is regulated. The double conveyance of the conductive sheet  60  accompanying the conveyance of the sheet  55  is prevented. 
     The conductive sheet  60  according to the first embodiment described above uses the fixed seal  70  to regulate a relative position with respect to the sheet tray  13 . On the other hand, the conductive sheet  60  according to the first to third modifications does not use the fixed seal  70 . Therefore, the sheet bundle package  50  according to the first to third modifications does not include the seal mount  79  as an inclusion. 
     As described in detail above, the conductive sheet  60  according to an embodiment can be provided between the sheet tray  13  of the image forming device  10  and the sheet  55 . The conductive sheet  60  has a conductivity in the region C that overlaps the wireless tag  57  of the sheet  55 . The conductive sheet includes the double conveyance prevention structure that prevents the conveyance in a state in which the conductive sheet overlaps the sheet. 
     The conductive sheet  60  is provided between the sheet tray  13  and the sheet  55 . The conductive sheet  60  has the conductive region C that overlaps with the wireless tag  57  of the sheet  55 . Accordingly, even if the number of sheets  55  remaining on the sheet tray  13  becomes one, the erroneous reading and writing for the wireless tag  57  of the sheet  55  can be prevented. 
     The double conveyance prevention structure according to the first embodiment regulates the relative movement with respect to the sheet tray  13 . 
     Even if the sheet  55  is conveyed from the sheet tray  13 , the relative movement between the conductive sheet  60  and the sheet tray  13  is regulated. Therefore, the double conveyance of the conductive sheet  60  accompanying the conveyance of the sheet  55  is prevented. 
     The conductive sheet  60  has a magnetic force and may be adsorbed on or attracted onto the sheet tray  13 . 
     The sheet bundle package  50  according to the embodiment includes the conductive sheet  60 , the sheet bundle  59 , and the package material  51  that are described above. The sheet bundle  59  is formed by stacking the sheets  55  each including the wireless tag  57 . The package material  51  packs the sheet bundle  59  and the conductive sheet  60 . 
     The sheet bundle  59  and the conductive sheet  60  are provided in the sheet bundle package  50 . The conductive sheet  60  having the same size as the sheet  55  is placed on the sheet tray  13  together with the sheet  55 . The conductive region C of the conductive sheet  60  overlaps with the wireless tag  57  of the sheet  55 . Accordingly, even if the number of sheets  55  remaining on the sheet tray  13  becomes one, the erroneous reading and writing for the wireless tag  57  of the sheet  55  can be prevented. 
     Second Embodiment 
       FIG.  15    is a plan view of a conductive sheet according to a second embodiment. The conductive sheet  60  according to the second embodiment is different from that according to the first embodiment in that the conductive sheet  60  according to the second embodiment includes a double conveyance prevention structure that prevents adsorption with the sheet  55 . The description of the second embodiment for the portion similar to that according to the first embodiment may be omitted. 
     The conductive sheet  60  includes a fine concave-convex portion  66  as the double conveyance prevention structure. The concave-convex portion  66  is formed on the entire upper surface of the conductive sheet  60 . The concave-convex portion  66  may be formed on a part of the upper surface of the conductive sheet  60 . The concave-convex portion  66  may be formed on the lower surface of the conductive sheet  60  in addition to the upper surface of the conductive sheet  60 . For example, the concave-convex portion  66  is formed by treating an upper surface of a plastic film, which is the base material or layer of the conductive sheet  60 , with a chemical. The concave-convex portion  66  may be formed by blasting the upper surface of the plastic film with fine particles. Another plastic film including the concave-convex portion  66  may be attached to the upper surface of the base material or layer of the conductive sheet  60 . 
     The sheet  55  is provided on the upper surface of the conductive sheet  60 . A gap is formed between the conductive sheet  60  and the sheet  55  due to the concave-convex portion  66  on the upper surface of the conductive sheet  60 . Accordingly, the adsorption due to static electricity between the conductive sheet  60  and the sheet  55  is prevented. The double conveyance of the conductive sheet  60  accompanying the conveyance of the sheet  55  is prevented. 
     As described above, the double conveyance prevention structure according to the second embodiment is the concave-convex portion  66  that prevents the adsorption between the conductive sheet  60  and the sheet  55 . 
     Even if the upper sheet  55  is conveyed, the lower conductive sheet  60  is less likely to be conveyed. Therefore, the double conveyance of the conductive sheet  60  accompanying the conveyance of the sheet  55  is prevented. 
     Third Embodiment 
       FIG.  16    is a plan view of a conductive sheet according to a third embodiment.  FIG.  17    is a plan view of a state in which the conductive sheet according to the third embodiment is mounted on a sheet placing portion. The conductive sheet  60  according to the third embodiment is different from that according to the first embodiment in that the conductive sheet  60  according to the third embodiment includes a double conveyance prevention structure that regulates a relative movement with respect to the end guide  16 . The description of the third embodiment for the portion similar to that according to the first embodiment may be omitted. 
     As illustrated in  FIG.  16   , the conductive sheet  60  includes a retaining aperture or second window portion  67  as the double conveyance prevention structure. A length of the conductive sheet  60  in the X direction is longer than that of the sheet  55 . The second window portion  67  is formed at an end portion of the conductive sheet  60  in the −X direction. The second window portion  67  penetrates the conductive sheet  60  in a thickness direction. 
     As illustrated in  FIG.  17   , the conductive sheet  60  is provided on the sheet tray  13 . The end guide  16  is inserted inside the second window portion  67 . The sheet  55  is provided on the conductive sheet  60 . The end guide  16  abuts against an end portion of the sheet  55  in the −X direction. 
     If a frictional force acts on the conductive sheet  60  accompanying the conveyance of the sheet  55 , an inner periphery of the second window portion  67  abuts against the end guide  16 . 
     Accordingly, the relative movement of the conductive sheet  60  with respect to the end guide  16  is regulated. The double conveyance of the conductive sheet  60  accompanying the conveyance of the sheet  55  is prevented. 
     As described above, the double conveyance prevention structure according to the third embodiment is the second window portion  67  that regulates the relative movement with respect to the end guide  16 . 
     Even if the sheet  55  is conveyed apart from the end guide  16 , the relative movement between the conductive sheet  60  and the end guide  16  is regulated. Therefore, the double conveyance of the conductive sheet  60  accompanying the conveyance of the sheet  55  is prevented. 
     Fourth Embodiment 
       FIG.  18    is a plan view of a conductive sheet according to a fourth embodiment.  FIG.  19    is a cross-sectional view taken along a line P-P in  FIG.  18   . The conductive sheet  60  according to the fourth embodiment is different from that according to the first embodiment in that the conductive sheet  60  according to the fourth embodiment includes a double conveyance prevention structure that engages with the tray window portion  14 . The description of the fourth embodiment for the portion similar to that according to the first embodiment may be omitted. 
     The conductive sheet  60  has an engage portion forming region  80  (a tab, a flap, a flange, etc.) as the double conveyance prevention structure. As viewed from the Z direction, an outer shape of the engage portion forming region  80  substantially matches the tray window portion  14  or is slightly smaller than the tray window portion  14 . The engage portion forming region  80  has a rectangular shape. Notches that penetrate the conductive sheet  60  are formed at both edge sides of the engage portion forming region  80  in the Y direction and an edge side of the engage portion forming region  80  in the −X direction. 
     The user bends the engage portion forming region  80  in the −Z direction with an edge side of the engage portion forming region  80  in the +X direction as a broken line to form an engage portion  81 . As illustrated in  FIG.  19   , the conductive sheet  60  is provided on the sheet tray  13  and the engage portion  81  is inserted into the tray window portion  14 . The user bends a tip of the engage portion  81  in the +X direction on a back side of the sheet tray  13 . The engage portion  81  engages with the tray window portion  14 . Accordingly, the relative movement of the conductive sheet  60  with respect to the sheet tray  13  is regulated. The double conveyance of the conductive sheet  60  accompanying the conveyance of the sheet  55  is prevented. 
     Since the engage portion  81  is formed by bending the engage portion forming region  80 , a third window portion  82  is formed in the engage portion forming region  80 . As viewed from the Z direction, at least a part of the tray window portion  14  is exposed from the third window portion  82 . The trigger  48  of the empty sensor  45  illustrated in  FIG.  7    passes through the third window portion  82  of the conductive sheet  60  and falls to the tray window portion  14 . The empty sensor  45  detects the absence of the sheet  55 . 
     A first modification of the fourth embodiment will be described. 
       FIG.  20    is a plan view of a conductive sheet according to a first modification of the fourth embodiment. The conductive sheet  60  according to the first modification includes a pair of engage portion forming regions  84 ,  85  as the double conveyance prevention structure instead of the engage portion forming region  80  according to the fourth embodiment. The description of the first modification for the portion similar to that according to the fourth embodiment may be omitted. 
     The pair of engage portion forming regions  84 ,  85  are the first engage portion forming region  84  and the second engage portion forming region  85  that are arranged in the Y direction. The first engage portion forming region  84  is formed in the +Y direction, and the second engage portion forming region  85  is formed in a −Y direction. As viewed from the Z direction, an entire outer shape of the pair of engage portion forming regions  84 ,  85  substantially matches the tray window portion  14  or is slightly smaller than the tray window portion  14 . Notches are formed at both edge sides of the pair of engage portion forming regions  84 ,  85  in the X direction. A notch parallel to the X direction is formed between the first engage portion forming region  84  and the second engage portion forming region  85 . 
     The user bends the first engage portion forming region  84  in the −Z direction with an edge side of the first engage portion forming region  84  in the +Y direction as a broken line to form a first engage portion  86 . The user bends the second engage portion forming region  85  in the −Z direction with an edge side of the second engage portion forming region  85  in the −Y direction as a broken line to form a second engage portion  87 . The first engage portion  86  and the second engage portion  87  are inserted into the tray window portion  14 . The user bends a tip of the first engage portion  86  in the +Y direction on the back side of the sheet tray  13 . The user bends a tip of the second engage portion  87  in the −Y direction on the back side of the sheet tray  13 . The pair of engage portions engage with the tray window portion  14 . Accordingly, the relative movement of the conductive sheet  60  with respect to the sheet tray  13  is regulated. The double conveyance of the conductive sheet  60  accompanying the conveyance of the sheet  55  is prevented. 
     The conductive sheet  60  according to the first embodiment described above uses the fixed seal  70  to regulate the relative position with respect to the sheet tray  13 . On the other hand, the conductive sheet  60  according to the second to fourth embodiments does not use the fixed seal  70 . Therefore, the sheet bundle package  50  according to the second to fourth embodiments does not include the seal mount  79  as an inclusion. 
     As described above, the double conveyance prevention structure according to the fourth embodiment is a region for forming the engage portion that engages with the tray window portion  14  formed on the sheet tray  13 . 
     Even if the sheet  55  is conveyed from the sheet tray  13 , the engage portion engages with the tray window portion  14 , so that the relative movement between the conductive sheet  60  and the sheet tray  13  is regulated. Therefore, the double conveyance of the conductive sheet  60  accompanying the conveyance of the sheet  55  is prevented. 
     According to the above-described embodiments, the conductive sheet  60  is provided on the sheet tray of the paper feed cassettes  11   a,    11   b  of the sheet placing portion  11 . On the other hand, the conductive sheet  60  may be provided on the manual feed tray (sheet tray)  11   c  of the sheet placing portion  11 . 
     The image forming device  10  according to the embodiment is a type of image processing device. On the other hand, the image processing device may be a decolorable device. The decolorable device performs a process of decoloring (erasing) the image formed on the sheet by a decolorable toner. 
     According to at least one of the embodiments described above, since the conductive region C overlapping the wireless tag  57  of the sheet  55  is formed, the erroneous reading and writing for the wireless tag  57  can be prevented. Since the double conveyance prevention structure is provided, the double conveyance of the conductive sheet  60  accompanying the conveyance of the sheet  55  can be prevented. 
     While several embodiments have been described, these embodiments have been presented by way of example and are not intended to limit the scope of the disclosure. Further, the concepts from the first embodiment, the second embodiment, the third embodiment, and the fourth embodiment may be combined. These embodiments can be implemented in other various forms, and various omissions, replacements, and changes can be made without departing from the spirit of the disclosure. The accompanying claims and these equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the disclosure.