JP2009196774A - Sheet carrying device and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheet carrying device and an image forming device capable of performing flexible static elimination based on the quantity of charges charged on a carried sheet. <P>SOLUTION: This sheet carrying device is provided with a charge granting roller pair 55 granting the charges to the conveyed sheet P in a state contacting the sheet and a pressure adjusting device 100 changing the contact pressure of the charge granting roller pair 55 to the sheet P in a discharging part 3. Also, the pressure adjusting device 100 changes the contact pressure of the charge granting roller pair 55 to the sheet P according to the sheet condition of the conveyed sheet P. Thus, flexible static elimination based on the quantity of charges charged on the carried sheet can be performed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a sheet conveying apparatus and an image forming apparatus, and more particularly to an apparatus for removing static electricity from a conveyed sheet.

  2. Description of the Related Art Conventionally, in an image forming apparatus such as an electrophotographic printer, when a sheet such as paper is conveyed therein, the conveyed sheet is charged by coming into contact with a guide plate or a conveyance roller that forms a conveyance path. It was. Therefore, when a plurality of conveyed sheets are stacked to form a bundle, depending on the charged state of the sheet bundle, suction or repulsion between the sheets occurs, which hinders alignment when stacking the sheets.

  Therefore, a sheet conveying apparatus that neutralizes the electrostatic charge of such a sheet using a charge neutralizing member has been proposed (see Patent Document 1). As shown in FIG. 15, the sheet conveying apparatus includes a charge neutralizing member 903 downstream of the paper discharge rollers 901 and 902. As a result, the sheet S charged at the time of image formation is brought into contact with and peeled off from the charge neutralizing member 903 when being conveyed by the paper discharge rollers 901 and 902, and a charge having a polarity opposite to the electrostatic charge on the surface of the sheet S is generated. It is assumed that the charge is eliminated by being given.

JP 2002-173242 A

  However, in the sheet conveying apparatus of Patent Document 1, the amount of charge applied by the charge neutralizing member 903 is determined by the material of the sheet S and the rigidity of the charge neutralizing member 903. Therefore, when the charge amount of the sheet S is large, there is a possibility that the charged charge of the sheet S remains even after contact with and peeling from the charge neutralizing member 903. Further, when the charge amount of the sheet S is small, there is a possibility that the charge application amount becomes excessive due to contact / peeling with the charge neutralizing member 903, and the sheet S is charged with a reverse polarity. As described above, when the sheets S in the state where the charged charges remain are discharged and stacked, the charge amount of the bundle of the sheets S increases as the number of stacked sheets increases, and the sheets to be stacked subsequently are increased. In other words, loading failure occurs due to the effects of adsorption and repulsion.

  Therefore, the present invention has been made in view of such a current situation, and provides a sheet conveying apparatus and an image forming apparatus capable of performing flexible static elimination based on the amount of charge charged on a sheet to be conveyed. It is the purpose.

  The present invention changes a sheet conveying unit that conveys a sheet, a charge applying unit that applies a charge to the sheet in contact with the sheet conveyed by the sheet conveying unit, and a contact pressure of the charge applying unit on the sheet Contact pressure changing means, wherein the contact pressure changing means changes the contact pressure of the charge applying means to the sheet according to the condition of the conveyed sheet.

  According to the present invention, the contact pressure applied to the sheet by the charge applying unit is changed according to the condition of the sheet to be conveyed, and the charge is applied. Therefore, flexible charge removal based on the amount of charge charged on the sheet to be conveyed It can be carried out.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram illustrating a schematic configuration of an image forming apparatus including a sheet conveying device according to a first embodiment of the present invention. 2 is a side sectional view of the vicinity of the stacking tray 56 in the image forming apparatus 1, and FIG. 3 is a perspective view showing the charge applying roller pair 55 and the pressure adjusting device 100 taken out. FIG. 4 is a diagram showing a charge train for obtaining an order of charge transfer of materials used for the charge application roller pair 55, and FIG. 5 is a block diagram for explaining a control system related to the charge application roller pair 55 and the pressure adjusting device 100. . The image forming apparatus integrally provided with the sheet conveying apparatus in the present embodiment is exemplified by a four-drum full color printer using an intermediate transfer belt.

  As shown in FIG. 1, the image forming apparatus 1 includes process units 5y, 5m, 5c, and 5k that develop four colors of yellow, magenta, cyan, and black, and an optical device 6y that irradiates each process unit with laser light. 6m, 6c, 6k. Further, the image forming apparatus 1 includes an intermediate transfer body unit 7 including an endless intermediate transfer belt 9 that sequentially superimposes and transfers the images developed by the process units 5y, 5m, 5c, and 5k. Further, a sheet feeding unit 40 is provided that separates and conveys the sheets P to which images on the intermediate transfer belt 9 are transferred one by one from the bundle state. Further, the image forming apparatus 1 conveys the sheet from the fixing unit 50 for fixing the image of the sheet P transferred by the intermediate transfer belt 9 and a sheet from the fixing unit 50 by a conveying roller pair (sheet conveying unit) 53 and the like. And a discharge section 3 that is stacked on a stacking tray (stacking means) 56.

  The process units 5y, 5m, 5c, and 5k are detachable from the main body of the image forming apparatus 1, and include a photosensitive drum 11 that is an image carrier, a charger 12 that uniformly charges the surface of the photosensitive drum 11, and a photosensitive drum. 11 has a developing unit 13 for developing the electrostatic latent image on the unit 11. In the image forming apparatus 1, the process units 5y, 5m, 5c, and 5k have the same configuration.

  The intermediate transfer body unit 7 includes the above-described intermediate transfer belt 9, drive roller 32, tension roller 33, secondary transfer counter roller 34, and primary transfer roller 35. At a position where the intermediate transfer belt 9 is sandwiched with the photosensitive drum 11, a primary transfer roller 35 that forms a primary transfer portion together with the photosensitive drum 11 is disposed oppositely. Reference numeral 36 denotes a secondary transfer roller disposed at a position sandwiching the intermediate transfer belt 9 of the secondary transfer counter roller 34.

  The paper feed unit 40 includes a pickup roller 43 provided above each of the paper feed cassettes 41. In addition, a retard roller pair 44a and 44b including a feed roller 44a and a retard roller 44b for separating and conveying the sheets P fed by the pickup roller 43 one by one is provided. The image forming apparatus 1 includes a manual sheet feeding unit 42 for feeding sheets from the side surface of the apparatus main body in addition to the sheet feeding unit 40.

  The fixing unit 50 includes a fixing roller 51 having a heat source and a pressure roller 52. Four colors of yellow, magenta, cyan, and black are transferred from the intermediate transfer belt 9 at the nip portion of the roller pair 51 and 52. The toner image on the second-transferred sheet P is melted and fixed.

  The discharge unit 3 includes a sheet conveying device that conveys (discharges) the sheet to the stacking tray 56, and includes a conveyance roller pair 53 and a conveyance roller pair (sheet conveyance unit) 54 disposed in the conveyance path 49. . Further, the discharge unit 3 includes a charge applying roller pair 55 as charge applying means disposed near the discharge port of the conveyance path 49. The sheet conveyed on the conveyance path 49 by the conveyance roller pair 53 and 54 is charged by contacting the charge application roller pair 55. As shown in FIG. 2, the charge applying roller pair 55 is a member in contact with the sheet conveyed by the conveying roller pairs 53 and 54, and is a driving side roller (charging member) 55a and a driven side roller (pressure contact member). 55b. The amount of charge applied to the sheet from the charge applying roller pair 55 varies depending on the pressure contact force between the driving side roller 55a and the driven side roller 55b. That is, as the pressure contact force increases, the contact pressure between the driving roller 55a serving as a charging member and the sheet increases, and accordingly, the amount of charge imparted by frictional charging also increases. The driving roller 55a rotates around a rotating shaft member 55a 'in response to rotation from a motor (not shown). The driven roller 55b has a support plate 101 having bearings for the rotation shaft of the driven roller 55b attached to both ends thereof. When the sheet P is conveyed by the rotation of the driving roller 55a, the sheet P is removed. Via the drive side roller 55a.

  Further, the discharge unit 3 described above includes a pressure adjusting device (contact pressure changing unit) 100 that adjusts a pressure contact force generated between the driving side roller 55a and the driven side roller 55b, which constitutes the charge applying roller pair 55. is doing. The pressure adjusting device 100 moves the driven roller 55b so as to be brought into pressure contact with the driving side roller 55a, and adjusts the pressure contact force at the time of the pressure contact. The pressure adjusting device 100 includes a stepping motor 102, a worm gear pair 103, a rotating shaft member 105, a cam 106, a spring 107, a support plate 101, a sensor flag 109, and a transmission sensor 110.

  The rotation amount (step value) of the stepping motor 102 is controlled based on detection results of sensors 57 and 58, which will be described later, and the driven roller 55b is advanced and retracted through the cam 106 by an amount corresponding to the rotation amount. As shown in FIG. 3, a worm 103b of a worm gear pair 103 is fixed to the tip of the rotating shaft of the stepping motor 102, and the worm 103b has a worm fixed to one end of the rotating shaft member 105. The wheel 103a is engaged. A disc-shaped sensor flag 109 is fixed to the other end of the rotating shaft member 105. The rotating shaft member 105 is arranged in a manner parallel to the driving side roller 55a and the driven side roller 55b.

  In addition, disk-shaped cams 106 are fixed in the vicinity of both end portions of the rotating shaft member 105 and slightly inside the worm wheel 103a and the sensor flag 109, respectively. The cam 106 is arranged in a state where one end of a substantially cylindrical spring 107 is in contact with the outer peripheral surface of the cam 106. The urging force generated by the spring 107 acts on the rotating shaft member 105 in a direction orthogonal to the rotating shaft member 105. A support plate 101 having a bearing is attached to the other end of the spring 107, and the support plate 101 supports both ends of the driven roller 55b with a bearing, thereby driving the driven roller 55b. Can rotate freely. Further, since the driven roller 55b is supported by the support plate 101 attached to the other side of the spring 107, the driven roller 55b disposed in parallel with the rotary shaft member 105 is also driven in parallel. The urging force of the spring 107 is received in the direction toward the side roller 55a.

  The discharge unit 3 includes a sensor (charge amount detection means) 57 on the upstream side of the charge application roller pair 55. This sensor 57 is, for example, a non-contact type electrostatic sensor that detects the amount of electric charge charged on the object, and is disposed upstream of the charge applying roller pair 55 in the sheet conveying direction, and determines the amount of electric charge of the conveyed sheet P. To detect.

  Further, the discharge unit 3 includes a sensor (second charge amount detection means) 58 on the downstream side of the charge application roller pair 55 and a stacking tray 56 for stacking sheets that have passed through the charge application roller pair 55. The sensor 58 is a non-contact type electrostatic sensor that detects the amount of electric charge charged on the object, and is directly above the stacking tray 56 for stacking the sheets P after the charge is applied by the charge applying roller pair 55 described above. It is arranged on the buttock. Thereby, the sensor 58 detects the charge amount of the sheet P and the sheet bundle PB stacked on the stacking tray 56.

  Next, a control system related to the charge applying roller pair 55 and the pressure adjusting device 100 described above will be described with reference to FIG.

  In the figure, a control device 70 has a CPU 71, a ROM 72 that stores a control program for the CPU 71 and various data, and a RAM 73 that is used as a work area during control operations by the CPU 71 and temporarily stores various data. . The sensors 57 and 58 and the transmission sensor 110 described above transmit the result signals detected by the sensors 57 and 58 and the transmission sensor 110 to the control device 70 via the input interface 75 that processes serial signals. The stepping motor 102 is controlled and driven by a control signal transmitted from the control device 70 via an output interface 76 that can process a serial signal based on the detection results of the sensors 57 and 58 and the transmission sensor 110.

  Next, an image forming operation of the image forming apparatus 1 having the above configuration will be described.

  For example, when a print command is received from an external host computer (not shown), the image forming operation of the image forming apparatus 1 is started. Thereby, for example, in the yellow process unit 5y, the surface of the photosensitive drum 11 is first negatively charged, and when the photosensitive device 11 is scanned by the optical device 6y, the potential at the scanning position is lowered to form an electrostatic latent image. . As a result, an electrostatic latent image corresponding to the yellow image component of the document is formed on the surface of the photosensitive drum 11.

  The electrostatic latent image is developed with yellow toner by the developing device 13 and visualized as a yellow toner image. The yellow toner image thus obtained is primarily transferred onto the intermediate transfer belt 9 by the primary transfer roller 35. After the toner image is transferred, the transfer residual toner adhering to the surface of the photosensitive drum 11 is removed by a cleaner (not shown) and used for the next image formation.

  The toner image forming operation as described above is also performed at a predetermined timing in the other process units 5m, 5c, and 5k. Then, the toner images of the respective colors formed on the respective photosensitive drums 11 are primarily transferred onto the intermediate transfer belt 9 by being sequentially superimposed on the respective primary transfer rollers 35.

  The four-color toner images transferred onto the intermediate transfer belt 9 in this way are arranged at positions where the secondary transfer counter roller 34 and the intermediate transfer belt 9 are sandwiched with the rotation of the intermediate transfer belt 9. The transfer roller 36 is moved to a secondary transfer portion.

  On the other hand, in parallel with the toner image forming operation as described above, the sheet P is fed from the sheet feeding cassette 41 by the pickup roller 43, and the sheet P is separated one by one by the pair of retard rollers 44a and 44b. After being separated, the sheet P is conveyed to the registration roller pair 46 by the conveyance roller pair 45 or the like. At this time, since the registration roller pair 46 stops rotating, the sheet P is abutted against the nip of the registration roller pair 46, and the skew is corrected. Note that the feeding of the sheet P as described above is also appropriately performed from the manual sheet feeding unit 42.

  When the skew is corrected as described above, the sheet P is conveyed to the secondary transfer unit by the registration roller pair 46 at a predetermined timing, and the toner image on the intermediate transfer belt 9 is transferred to the secondary transfer unit. The At this time, the toner that is not completely transferred and remains on the intermediate transfer belt 9 is collected by the cleaning device 37 and stored in the collected toner container 38. The sheet P on which the toner image has been transferred subsequently reaches the fixing unit 50. The fixing unit 50 fixes the image on the sheet P with the fixing roller 51 and the pressure roller 52. Thereafter, the paper is transported along the transport path 49 by the transport roller pairs 53 and 54, and is transported to the stacking tray 56 through the charge application roller pair 55.

  Next, an operation associated with the configuration of the charge applying roller pair 55, the sensors 57 and 58, and the pressure adjusting device 100 described above will be described.

  When the stepping motor 102 of the pressure adjusting device 100 is driven to rotate, the worm 103b of the worm gear pair 103 rotates. When the worm 103b rotates, the rotation is transmitted to the worm wheel 103a meshed with the worm 103b, and the rotary shaft member 105 attached concentrically with the worm wheel 103a rotates together. Further, when the rotary shaft member 105 rotates, the cam 106 moves forward and backward in the direction of the charge applying roller pair 55. At this time, since the end of the spring 107 slides along the outer peripheral surface of the cam 106, when the cam 106 advances to the charge applying roller pair 55 side, the urging force by the spring 107 increases, and the driven roller 55b is driven. The pressure contact force with respect to the side roller 55a increases. On the contrary, when the cam 106 is retracted from the charge applying roller pair 55 side, the urging force by the spring 107 is decreased, and the pressure contact force of the driven roller 55b with respect to the driving roller 55a is decreased. The pressure contact force applied by the driven roller 55b to the driving roller 55a by the urging force of the spring 107 as described above may be abbreviated as “pressure of the charge applying roller pair 55” below.

  The advance / retreat position of the cam 106 is determined by the control device 70 in the image forming apparatus 1 based on the detection results of the sensors 57 and 58. That is, the control device 70 determines the charge application roller pair 55 necessary for generating the charge of the reverse polarity for neutralizing the charge amount according to the charge amount charged on the sheet P detected by the sensor 57. The pressure contact force (that is, the contact pressure of the charge applying roller pair 55 with respect to the sheet P) is determined. For example, the pressure contact force is determined as a step value of the stepping motor 102 by the control device 70 referring to a data table or the like stored in advance in the ROM 72 based on the charge amount detected from the sheet P. The advance / retreat position of the cam 106 is determined by the step value of the stepping motor 102, and contact pressure corresponding to the advance / retreat position is applied to the sheet P.

  A sensor 58 downstream of the charge application roller pair 55 detects the amount of charge charged in the bundle of sheets stacked on the stacking tray 56. The charge amount detected by the sensor 58 is referred to by the control device 70 which is also a correction means so as to correct the charge amount which is the detection result of the sensor 57, that is, to correct the contact pressure on the sheet P. Is done. For example, when the sensor 57 detects a negative charge amount from the sheet P in a state where the positive charge amount is detected from the sheet bundle on the stacking tray 56 by the sensor 58, the determination is made only by the detection result of the sensor 57. A positive charge is applied by the charge application roller pair 55. However, if a positive charge is applied to the sheet P here, the positive charge amount of the sheet bundle stacked on the stacking tray 56 is increased depending on the applied charge amount. Therefore, the amount of charge applied by the charge application roller pair 55 is not simply applied to the sheet P based on the detection result of the sensor 57 but the detection result of the sensor 58 is reflected on the detection result of the sensor 57. Correct. As a result, it is possible to adjust the direction in which the deviation of the charge amount charged in the sheet bundle loaded on the stacking tray 56 is also suppressed.

  Note that the amount of electric charge charged to the sheet depends on each element such as the type of sheet (details will be described later), so the amount of electric charge detected by the sensors 57 and 58 actually depends on each element described above. In some cases, the control device 70 corrects the weight by appropriate weighting. Including the charge amount detected by the sensors 57 and 58 and the elements described above for correcting the charge amount, the following description is given when determining the contact pressure of the charge applying roller pair 55 on the sheet P. This is called a sheet condition.

  Here, each element of the above-described sheet condition will be described in more detail. Among these elements, data such as the type of sheet such as plain paper, coated paper, and special paper, and the sheet size are included in the image forming apparatus 1. Input from the operation panel (not shown) of the main body by the user. Further, physical properties (surface properties) such as sheet stiffness, thickness, basis weight, surface resistance, and smoothness are input by the user from the operation panel described above or detected by a sensor (not shown). Is done. Further, information on the amount of toner on the image-formed sheet (toner application amount) is data based on the irradiation amount of laser light at the time of image formation, and the control device 70 of the main body of the image forming apparatus 1. Held at. The CPU 71 in the control device 70 determines the sheet condition based on these elements or by predicting the charge amount of the sheet conveyed based on these elements. Here, when predicting the charge amount of the conveyed sheet as described above, for example, data such as a toner loading amount and a paper surface resistance value (paper type) are used. When the amount of applied toner is large, the negative charge amount on the sheet becomes relatively large, and the chargeability of the sheet varies depending on the surface resistance value (paper type) of the paper. . Therefore, by acquiring data such as the toner loading amount and the surface resistance value (paper type) of the paper, the advance / retreat position of the cam 106 by the stepping motor 102 is driven to move in the vicinity of the position corresponding to the data. It is possible to take pre-measures such as.

  Incidentally, a sensor flag 109 is attached to the shaft end portion of the rotating shaft member 105 on the side opposite to the worm wheel 103a. A shield plate A is attached to the outer periphery of the sensor flag 109, and the home position (initial position) of the cam 106 can be detected by shielding the transmission part of the transmission sensor 110. As a result, the stepping motor 102 described above can be reliably returned to the initial position, so that the pressure contact force of the driven roller 55b based on the rotation amount (step value) of the stepping motor 102 can be accurately applied to the driving roller 55a. it can.

  On the other hand, the material of the charge applying roller pair 55 as described above is as shown in FIG. 4 on the basis of the chargeability of the sheet and the charging condition (either positive or negative, the amount of charge, etc.) of the conveyed sheet. It can be selected based on the charge train that represents the order of ease of charging. Since the image formed on the sheet is formed with toners such as acrylic and polyethylene as the main raw material, the material of the charge applying roller pair 55 when the sheet is positively charged is cellophane whose order is lower than those. , Vinyl chloride, polytetrafluoroethylene and the like are selected. When the sheet is negatively charged, the material of the sheet is assumed to be, for example, paper, and a higher material such as acetate, glass, human hair, nylon or the like is selected. When a sheet is conveyed by a roller made of such a material, frictional charging due to friction or contact peeling charging due to peeling of the contact surface (also simply referred to as peeling charging) occurs, and a desired direction (positive or negative polarity) Can be applied to the sheet.

  Note that the polarity charged when the conveyed sheet reaches the charge applying roller pair 55 is mainly determined by the charger 12 described above, and has a constant charging direction of either positive or negative. For this reason, the charge application roller pair 55 may be provided with either positive or negative.

  Next, the operation of the charge applying roller pair 55, the sensors 57 and 58, and the pressure adjusting device 100 will be described with reference to the flowchart of FIG.

  That is, as shown in FIG. 6, the sensor 57 detects the charge amount (charge amount) of the sheet P conveyed by the conveyance roller pair 53, 54, etc. (step S1). The pressure (pressure contact force) of the charge application roller pair 55 is determined according to the detection result of the sensor 57 in step S1 (step S2). While applying the pressing force determined in step S2, the sheet P is discharged onto the stacking tray 56 by the charge applying roller pair 55 (step S3).

  In step S3, the sensor 58 detects the charge amount of the bundle of sheets P (sheet bundle PB) discharged to the stacking tray 56 (step S4). It is determined whether the charging direction (polarity) detected in step S4 is the same as the direction applied by the charge applying roller pair 55 (step S5).

  If it is determined in step S5 that the directions are not the same (that is, reverse polarity), correction is performed so that the pressure of the charge application roller pair 55 is raised (base up) (step S6). This is because, for example, when the charging direction applied by the charge application roller pair 55 is negative and the sheet bundle PB is positive, the charge application roller pair 55 is guided to neutralize the charge of the sheet bundle PB. It correct | amends so that the negative charge amount provided by may be increased. If it is determined in step S5 that the directions are the same (that is, the same polarity), the pressure of the charge application roller pair 55 is corrected to be lowered (base down) (step S7). This is because, for example, when the charging direction applied by the charge application roller pair 55 is negative and the sheet bundle PB is negative, the negative charge amount of the sheet bundle PB is not increased. The correction is made so as to reduce the amount of charge applied. Therefore, when the sheet is transported after steps S6 and S7 (step S8), the sheet is given a charge that does not increase or decrease the charge amount of the sheet bundle PB on the stacking tray 56. An increase in the charge amount of the sheet bundle PB is suppressed.

  When the sheet P is conveyed by the charge application roller pair 55, the driven roller 55b is pushed down by the thickness of the sheet P, and a force for rotating the rotating shaft member 105 in the reverse direction is generated. Therefore, the stepping motor 102 does not step out.

  In the present embodiment described above, the discharge unit 3 applies the charge application roller pair 55 that applies charge to the sheet in contact with the conveyed sheet P, and the contact pressure of the charge application roller pair 55 on the sheet P. A pressure adjusting device 100 to be changed. The pressure adjusting device 100 changes the contact pressure of the charge applying roller pair 55 on the sheet P in accordance with the sheet condition of the conveyed sheet P. Thereby, flexible static elimination based on the amount of electric charge charged on the sheet P to be conveyed can be performed.

  Further, the charge applying roller pair 55 includes a driving roller 55a that applies charge to the sheet P according to charging according to the contact pressure, and the pressure adjusting device 100 is driven according to the condition of the sheet in the conveyed sheet P. The contact pressure of the side roller 55a on the sheet P is changed. Thereby, the contact pressure of the driving roller 55a with respect to the conveyed sheet P can be adjusted, and the amount of charge applied to the sheet P can be adjusted.

  The charge application roller pair 55 includes a driven roller 55b that is in pressure contact with the driving roller 55a. Then, the pressure adjusting device 100 changes the contact pressure of the driving side roller 55a to the sheet by adjusting the pressure contact force of the driven side roller 55b with respect to the driving side roller 55a in accordance with the sheet condition of the conveyed sheet P. To do. Thereby, the contact pressure of the driving roller 55a with respect to the conveyed sheet P can be adjusted, and the amount of charge applied to the sheet P can be adjusted.

  Further, the discharge unit 3 includes a sensor 57 that detects the charge amount of the conveyed sheet P, and the pressure adjusting device 100 neutralizes the charge amount detected by the sensor 57 so that the sheet of the charge applying roller pair 55 is neutralized. Change the contact pressure to P. Accordingly, the charge application by the charge application roller pair 55 can be flexibly performed based on the charged state of the conveyed sheet P. Therefore, since the charged state of the sheet bundle PB stacked on the stacking tray 56 is stabilized, even when the sheets having been provided with charges by the charge applying roller pair 55 are stacked, adsorption or repulsion is unlikely to occur, and stacking failure is caused. Is suppressed.

  The discharge unit 3 also includes a stacking tray 56 for stacking sheets after the charge is applied by the charge applying roller pair 55, and a sensor 58 for detecting the charge amount of the sheets after applying the charge stacked on the stacking tray 56. Is provided. Further, the discharge unit 3 includes a control device 70 that corrects the charge amount detected by the sensor 57 based on the charge amount detected by the sensor 58. As a result, not only the charged state (charge amount) of the conveyed sheet P but also the charged state (charge amount) of the sheet bundle already stacked on the stacking tray 56 is corrected and corrected. A flexible and appropriate charge can be applied.

  Further, the driving side roller 55a and the driven side roller 55b represent an order of ease of charging as shown in FIG. 4 based on at least one of the charging property of the sheet P and the charging state of the conveyed sheet P. It is made of a material selected from the charged column. As a result, the materials of the members such as the driving side roller 55a and the driven side roller 55b can be selected easily and accurately.

  Further, the driving side roller 55a and the driven side roller 55b are formed in a roller shape, and convey a sheet by their rotation. As a result, the mechanism for transporting the sheet and the mechanism for imparting electric charge can be combined into one, so that the number of manufacturing steps can be reduced and the space in the apparatus can be saved.

  Next, an image forming apparatus provided with a sheet processing apparatus as a sheet conveying apparatus according to a second embodiment of the present invention will be described with reference to the drawings. FIG. 7 is a cross-sectional view illustrating an example of an image forming apparatus including the sheet processing apparatus according to the embodiment of the present invention.

  In FIG. 1, reference numeral 200 denotes a copying machine. The copying machine 200 includes an image forming apparatus 201, a folding processing unit 205, and a finisher (sheet conveying apparatus) 206 that is a sheet processing apparatus. The image forming apparatus 201 includes a sheet feeding unit 202 that feeds sheets stored in a cassette, an image forming unit 203 that forms an image on a sheet fed by the sheet feeding unit 202, and the like. The sheet on which the image is formed by the image forming unit 203 is discharged from the image forming apparatus 201 by a discharge roller (not shown) and transferred to the folding processing unit 205.

  The folding processing unit 205 includes a conveyance path (not shown) for introducing the sheet discharged from the image forming apparatus 201 and guiding it to the finisher 206 side. A plurality of conveyance roller pairs are provided on the conveyance path. It has been. The folding processing unit 205 performs folding processing (for example, Z-folding) on the sheet discharged from the image forming apparatus 201 according to the setting, and directly sends the sheet to the finisher 206 through the above-described conveyance path. Further, the finisher 206 performs a binding process, a bookbinding process, and the like on the sheet discharged from the folding processing unit 205.

  Next, the configuration of the finisher 206 will be described with reference to FIG. FIG. 8 is a detailed sectional view of the finisher 206.

  The finisher 206 takes in sheets from the image forming apparatus 201, aligns the plurality of taken-in sheets, bundles them as one sheet bundle, performs sort processing, and non-sort processing. The finisher 206 performs a stapling process (binding process) and a bookbinding process for stapling the rear end side of the sheet bundle, and as shown in FIG. 8, the staple unit 600 for stapling the sheet and the sheet bundle are folded in two. A saddle stitch bookbinding section 800 for bookbinding. The folding processing unit 205, the staple unit 600, and the saddle stitch binding unit 800 are controlled by a finisher control unit (not shown) provided in the finisher 206. The finisher control unit receives various information through communication with a control device provided in the image forming apparatus 201 and controls the finisher 206 as a whole. The finisher control unit may be provided integrally with a control device provided in the image forming apparatus 201 so as to control the finisher 206 directly from the image forming apparatus 201.

  Here, as shown in FIG. 8, the finisher 206 includes a conveyance path 620 for taking the sheet conveyed through the folding processing unit 205 into the apparatus, and the conveyance path 620 includes a pair of inlet rollers. 601 and conveyance roller pairs 602 to 608 are provided. A punch unit 630 is provided between the conveying roller pair 602 and the conveying roller pair 603. The punch unit 630 operates as necessary, and punches (perforates) a rear end portion of the conveyed sheet. I do.

  Further, a switching member 613 is provided at the end of the transport path 620, and the switching member 613 switches the path between the upper discharge path 621 and the lower discharge path 622 that are connected downstream. . Here, the upper paper discharge path 621 is for discharging paper to the upper stack tray 701 by the upper paper discharge roller 609, and the lower paper discharge path 622 is provided with transport roller pairs 610 to 612. This is for discharging paper to the processing tray 650.

  Reference numeral 614 denotes a switching member that switches the conveyance path to a lower discharge path 622 or a saddle discharge path 623, which will be described later. The sheet is discharged to the processing tray 650 by switching the switching member 614 to the solid line position. It has become.

  After the sheets are discharged to the processing tray 650, the sheets are sequentially bundled while being aligned, and sorting processing and stapling processing are performed according to settings in an operation unit (not shown) provided in the image forming apparatus 201. Is done. Thereafter, the sheet is discharged to the stack trays 700 and 701 by the bundle discharge roller pair 651. Note that the stapling process is performed by the stapler 660, and the stapler 660 can be moved in the width direction and can be stapled at an arbitrary position on the sheet.

  Further, the stack trays 700 and 701 are configured to be movable in the vertical direction. The upper stack tray 701 is a sheet from the upper discharge path 621 and the processing tray 650, and the lower stack tray 700 is a processing tray. Sheets from 650 can be received. In this way, a large number of sheets can be stacked on the stack trays 700 and 701, and the stacked sheets are regulated and aligned by the rear end guide 710 extending in the vertical direction at the rear end.

  On the other hand, the sheet passes through the saddle discharge path 623 and is sent to the saddle stitch binding unit 800 by switching of the switching member 614 provided in the middle of the lower discharge path 622. In this case, the sheet is first delivered to a pair of saddle entrance rollers (not shown), the entrance is selected by a switching member 806 operated by a solenoid according to the size, and is carried into the storage guide 803 of the saddle stitch bookbinding section 800. Is done.

  The sheet thus carried into the storage guide 803 is conveyed by the sliding roller 804 until the leading end contacts the sheet positioning member 805 that can move in the vertical direction. The saddle entrance roller pair (not shown) and the sliding roller 804 are driven by a motor M1.

  In addition, a stapler 820 including a driver 820a that protrudes a needle that is opposed to the storage guide 803 and an anvil 820b that bends the protruded needle is provided in the middle of the storage guide 803.

  Here, the sheet positioning member 805 stops at a position where the central portion in the sheet conveyance direction becomes the binding position of the stapler 820 when the sheet is loaded. The sheet positioning member 805 is movable in the vertical direction under the driving of the motor M2, and can change its position according to the sheet size.

  A pair of folding rollers 810a and 810b are provided on the downstream side of the stapler 820, and a protruding member 830 is provided at a position opposite to the pair of folding rollers 810a and 810b. The protruding member 830 has a position retracted from the storage guide 803 as a home position (initial position), and protrudes toward the stored sheet bundle by driving the motor M3.

  By projecting toward the sheet bundle in this way, the sheet bundle can be pushed into the nip between the pair of folding rollers 810a and 810b, and thereby the sheet bundle can be folded. The protruding member 830 returns to the home position again after the sheet bundle is pushed in.

  On the other hand, between the pair of folding rollers 810a and 810b into which the sheet bundle is pushed, a pressure sufficient to crease the sheet bundle is applied by a spring (not shown), thereby passing through the pair of folding rollers 810a and 810b. At this time, the sheet bundle is creased. The sheet bundle thus creased is then discharged to the folded bundle discharge tray 850 via the first fold conveying roller pair 811a, 811b and the second fold conveying roller pair 812a, 812b.

  The first folding roller pair 811a, 811b and the second folding conveyance roller pair 812, 812b, which are these two conveying means, are also subjected to sufficient pressure to convey and stop the folded sheet bundle. ing. The pair of folding rollers 810a and 810b, the first pair of folding and conveying rollers 811a and 811b, and the pair of second folding and conveying rollers 812a and 812b are rotated at the same speed by the same motor M4.

  When the sheet bundle bound by the stapler 820 is folded, the sheet positioning member 805 is moved away from the position at the time of the stapling process so that the staple position of the sheet bundle comes to the nip position of the pair of folding rollers 810a and 810b after the stapling process is finished. Descent a predetermined distance. Thereby, the sheet bundle can be folded around the position where the stapling process is performed.

  In FIG. 8, 813 is a conveyance guide that connects between the folding roller pairs 810a and 810b and the first fold conveyance roller pair 811a and 811b, and 814 is the first fold conveyance roller pair 811a and 811b and the second fold conveyance roller pair 812a. , 812b.

  Reference numeral 815 denotes an alignment plate pair that has a surface that protrudes from the storage guide 803 around the outer peripheral surfaces of the pair of folding rollers 810a and 810b and aligns the sheets stored in the storage guide 803. The alignment plate pair 815 is positioned in the width direction of the sheet by being driven by the motor M5 and moving in the nipping direction with respect to the sheet.

  Meanwhile, a crease press unit 860 for reinforcing the folds of the sheet bundle is provided downstream of the second fold conveyance roller pair 812a and 812b so as to spatially overlap the fold bundle discharge tray 850. Here, the crease press unit 860 includes a press roller pair 861 that is a pressing unit that rotates along the fold while pressing the fold of the folded sheet bundle, and a press holder 862 that is a holding unit that supports the press roller pair 861. have. The folds are strengthened by moving the press holder 862 in the crease direction while the press roller pair 861 nips the folds of the sheet bundle.

  Next, the positive charge application roller pair 801 and the negative charge application roller pair 802 will be described with reference to FIGS. 9 is a sectional view showing the saddle stitch bookbinding portion 800 taken out, FIG. 10 is a perspective view showing the positive charge applying roller pair 801 and the pressure adjusting device 8010, and FIG. 11 is a positive charge applying roller pair 801. 4 is a side sectional view of a pressure adjustment device 8010. FIG. 12 is a perspective view showing a first operation example of the positive charge application roller pair 801 and the pressure adjustment device 8010. FIG. 13 is a second operation example of the positive charge application roller pair 801 and the pressure adjustment device 8010. It is a perspective view shown. The positive charge application roller pair (charge application unit, first charge application unit) 801 and the negative charge application roller pair (charge application unit, second charge application unit) 802 are the same except that the materials of the rollers are different. Therefore, only the positive charge application roller pair 801 will be described below.

  As shown in FIG. 9, the positive charge application roller pair 801 includes a roller (charging member) 8011 and a roller (pressure contact member) 8012 that are members that come into contact with the sheet conveyed by the conveyance roller pair 611 and the like. Yes. The roller 8011 receives rotation from a motor (not shown) and rotates around the rotation shaft 8011a. The roller 8012 is provided with support members 8013 having bearings of a rotation shaft member (not shown) of the roller 8012 at both ends thereof. When the sheet P is conveyed by the rotation of the roller 8011, the support member 8013 is interposed via the sheet P. Then, the roller 8011 is driven to rotate.

  The sensor 807 (first charge amount detection means) is, for example, a non-contact type electrostatic sensor that detects the amount of charge charged on the object, and is disposed upstream of the positive charge application roller pair 801 in the sheet conveyance direction. The charge amount of the sheet P to be applied is detected (see FIG. 8).

  The pressure adjusting device (adjusting means) 8010 includes a motor M6 that is a stepping motor, a belt 8018, a pulley 8017, a cam shaft 8016, a cam 8015, a link 8014, a support member 8013, a shielding plate A, and a transmission sensor S. . The pressure adjusting device 8010 moves the roller 8012 so as to come into pressure contact with the roller 8011 and adjusts the pressure contact force at the time of this pressure contact.

  The rotation amount of the motor M6 is controlled by the above-described finisher control unit based on the detection result of the sensor 807, and the roller 8012 is advanced and retracted through the cam 8015 by an amount corresponding to the rotation amount. The motor M6 transmits the rotation from the front end of the rotation shaft to the pulley 8017 via the belt 8018.

  A cam shaft 8016 is provided at the center of the pulley 8017 so that a disc-shaped cam 8015 is concentrically attached to both ends of the cam shaft 8016. The cam shaft 8016 is disposed in parallel with the rollers 8011 and 8012. A flat shielding plate A for detecting a home position (initial position) within the rotation range of the cam 8015 is formed at the peripheral portion of the cam 8015 described above, and the shielding plate A is provided in the vicinity of the cam 8015. A transmission sensor S for detecting the shielding state is disposed.

  A link 8014 that swings in accordance with the rotation of the cam 8015 is attached to the peripheral end portion of the cam 8015 attached to both ends of the cam shaft 8016. A support member 8013 is attached to each end of the link 8014. The support member 8013 includes a slide member 8019 and a spring B (see FIG. 11) fastened to the link 8014. Further, the support member 8013 supports the roller 8012 by rotating both ends of the roller 8012 with bearings.

  Next, operations associated with the configuration of the positive charge application roller pair 801 and the pressure adjustment device 8010 described above will be described.

  When the motor M6 of the pressure adjusting device 8010 is driven to rotate, the pulley 8017 rotates via the belt 8018. When the pulley 8017 rotates, the rotation is transmitted to the cam shaft 8016 provided on the pulley 8017, and the cam 8015 attached concentrically with the pulley 8017 rotates together. When the cam 8015 rotates, the link 8014 swings and operates so as to advance and retreat in the direction of the positive charge application roller pair 801. Here, when the link 8014 advances to the positive charge application roller pair 801 side (in the direction of arrow C in FIG. 11), the spring B is pressed by the slide member 8019, so that the urging force by the spring B increases and the roller 8012. The pressure contact force against the roller 8011 increases (for example, FIG. 12). On the contrary, when the link 8014 is retracted from the positive charge applying roller pair 801 side, the urging force by the spring B is decreased, and the pressure contact force of the roller 8012 to the roller 8011 is decreased. When the link 8014 is retracted to the maximum from the positive charge application roller pair 801 side, as shown in FIG. 13, the roller 8012 may be separated to be in a non-contact state with respect to the conveyed sheet. it can. Note that the home position of the rotational range of the cam 8015 is detected based on the timing at which the shielding plate A shields between the transmission sensors S.

  Next, the operation of the positive charge applying roller pair 801, the sensor 807, and the pressure adjusting device 8010 will be described.

  That is, the sheet P conveyed from the image forming apparatus 201 to the finisher 206 is charged in a certain direction (polarity) due to the influence of a charger (not shown) included in the image forming apparatus 201. However, since it comes into contact with a plurality of members such as the conveyance path 620 in the finisher 206 and the entrance roller pair 601, the amount of charge charged in the sheet P and the charging direction can change due to friction with these members. . Therefore, in the present embodiment, according to the detection result of the charge amount of the sheet P by the sensor 807, if the sheet P is negatively charged, the positive charge applying roller pair 801 is negative if it is positively charged. The charge applying roller pair 802 can be brought into contact according to the respective situations. For example, in the positive charge application roller pair 801, the motor M6 of the pressure adjusting device 8010 is rotated, and the rotation amount from the home position of the cam 8015 is controlled, so that the rollers 8011 and 8012 are in a contact / non-contact state. Can be changed. Furthermore, when the roller 8011 and the roller 8012 are in contact with each other, the amount of charge applied to the conveyed sheet can be adjusted by controlling the amount of rotation of the cam 8015 to change the pressure contact force therebetween. It will be possible. As a result, depending on the positive charge application roller pair 801 and the negative charge application roller pair 802 in the present embodiment, it becomes possible to apply electric charges in accordance with the charging direction of the sheet P conveyed into the finisher 206. . Furthermore, at the time of each contact, not only the charging direction but also the charge removal process can be performed so that the amount of charge applied to the sheet P can be changed flexibly and effectively.

  On the other hand, as shown in the sheet P of FIG. 14, the sheet conveyed to the finisher 206 may have a large charge amount in the image region M and a small charge amount in the non-image region N. In such a case, when the positive charge imparting roller pair 801 or the negative charge imparting roller pair 802 is brought into contact, the contact pressure with respect to each sheet P is large in the first image area M, and in the second non-image area N. The stepping motor 102 is controlled to make it smaller. As a result, different amounts of charges can be applied on the sheet P, and the sheet P as illustrated in FIG. 14 can be neutralized.

  In the second embodiment described above, the positive charge application roller pair 801 for applying positive charge and the negative charge application roller pair 802 for applying negative charge are provided, and the positive charge application roller pair 801 and the negative charge application are provided. A charge is applied to the sheet P by one of the roller pairs 802. Accordingly, it is possible to flexibly apply charges by the positive charge applying roller pair 801 and the negative charge applying roller pair 802 based on the charged state of the conveyed sheet P.

  In addition, for example, the positive charge application roller pair 801 includes a roller 8011 that applies charge due to charging according to the contact pressure to the sheet P, and the pressure adjustment device 8010 corresponds to the sheet condition in the conveyed sheet P. The contact pressure of the roller 8011 to the sheet P is changed. As a result, the contact pressure of the roller 8011 with respect to the conveyed sheet P can be adjusted, and the amount of charge applied to the sheet P can be adjusted.

  Further, for example, the positive charge application roller pair 801 includes a roller 8012 that is pressed against the roller 8011. Then, the pressure adjusting device 8010 changes the contact pressure of the roller 8011 to the sheet by adjusting the pressure contact force of the roller 8012 to the roller 8011 in accordance with the sheet condition of the conveyed sheet P. As a result, the contact pressure of the roller 8011 with respect to the conveyed sheet P can be adjusted, and the amount of charge applied to the sheet P can be adjusted.

  The positive charge applying roller pair 801 and the negative charge applying roller pair 802 apply charge to the sheet by either of them based on the detection result of the sensor 807. As a result, not only a positive or negative charge can be applied, but also a positive or negative charge can be applied flexibly based on the charged state of the sheet. In other words, this means that either the positive charge application roller pair 801 or the negative charge application roller pair 802 does not apply charge depending on the detection result of the sensor 807. Here, the case where the charge is not applied may be a mode in which a zero charge is applied at the time of contact with the sheet. For example, the roller 8011 and the roller 8012 are separated from each other. The mode which can be mentioned can be mentioned.

  Further, for example, the roller 8011 and the roller 8012 are each formed in a roller shape, and the sheet is conveyed by rotation thereof. As a result, the mechanism for transporting the sheet and the mechanism for imparting electric charge can be combined into one, so that the number of manufacturing steps can be reduced and the space in the apparatus can be saved.

  In the first and second embodiments described above, for example, even if the charge applying roller pair 55 does not include the driven side roller 55b as the pressure contact member, the driving side roller 55a as the charging member is provided. The structure only provided may be sufficient. In this case, the drive-side roller 55a can be moved, and the contact pressure on the sheet P can be changed by changing the positional relationship with the conveyed sheet P.

  As described above, the sheet conveying apparatus and the image forming apparatus according to the present invention are particularly suitable for a sheet conveying apparatus and an image forming apparatus that require stabilization of sheet stacking.

1 is a diagram illustrating a schematic configuration of an image forming apparatus including a sheet conveying device according to a first embodiment of the present invention. 3 is a side cross-sectional view of the vicinity of a stacking tray in the image forming apparatus. FIG. It is the perspective view which took out and showed the charge provision roller pair and the pressure adjustment apparatus. It is a figure which shows the electrification row | line | column of the material used for a charge provision roller pair. It is a block diagram explaining the control system which concerns on a charge provision roller pair and a pressure adjustment apparatus. It is a flowchart explaining the effect | action by an electric charge provision roller, a sensor, and a pressure regulator. 1 is a cross-sectional view illustrating an example of an image forming apparatus including a sheet processing apparatus according to an embodiment of the present invention. It is a detailed sectional view of a finisher. It is sectional drawing which takes out and shows a saddle stitch bookbinding part. It is a perspective view which takes out and shows a positive charge provision roller pair and a pressure adjusting device. It is side sectional drawing of a positive charge provision roller pair and a pressure adjustment apparatus. It is a perspective view which shows the 1st operation example of a positive charge provision roller pair and a pressure adjustment apparatus. It is a perspective view which shows the 2nd operation example of a positive charge provision roller pair and a pressure adjustment apparatus. It is explanatory drawing which shows the example of the sheet | seat in which the image was formed. It is sectional drawing which shows the example of the conventional static elimination method of a sheet | seat.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 3 Sheet conveying apparatus (discharge part)
55a Charging member (driving side roller), member in contact with sheet (driving side roller)
55b Pressure contact member (driven roller), member in contact with sheet (driven roller)
53 Sheet conveying means (pair of conveying rollers)
54 Sheet conveying means (pair of conveying rollers)
55 Charge application means (pair of charge application rollers)
56 Loading means (loading tray)
57 Charge detection means (sensor)
58 Second charge amount detection means (sensor)
70 Correction means (control device)
100 Contact pressure changing means (pressure adjusting device)
DESCRIPTION OF SYMBOLS 201 Image forming apparatus 203 Image forming part 206 Sheet conveying apparatus (finisher)
611 Sheet conveying means (conveying roller pair)
801 Charge application means (positive charge application roller pair), first charge application unit (positive charge application roller pair)
802 Charge application means (negative charge application roller pair), second charge application unit (negative charge application roller pair)
807 Charge detection means (sensor)
8010 Contact pressure changing means (pressure adjusting device)
8011 Charging member (roller), member in contact with sheet (roller)
8012 Pressure contact member (roller), member in contact with sheet (roller)
P sheet

Claims (9)

Sheet conveying means for conveying the sheet;
A charge applying unit that applies a charge to the sheet in contact with the sheet conveyed by the sheet conveying unit;
Contact pressure changing means for changing the contact pressure to the sheet of the charge applying means,
The contact pressure changing means changes the contact pressure to the sheet of the charge applying means according to the condition of the conveyed sheet.
A sheet conveying apparatus. The charge applying unit includes a charging member that applies charge to the sheet by charging according to the contact pressure, and the contact pressure changing unit is configured to contact the sheet with the charging member according to the condition of the sheet to be conveyed. Change the
The sheet conveying apparatus according to claim 1. The charge applying means has a pressure contact member that is in pressure contact with the charging member,
The contact pressure changing means changes a contact pressure of the charging member to the sheet by adjusting a pressing force of the pressing member to the charging member according to a condition of the conveyed sheet.
The sheet conveying apparatus according to claim 2. A charge amount detecting means for detecting a charge amount of the sheet conveyed by the sheet conveying means;
The contact pressure changing means changes the contact pressure to the sheet of the charge applying means so as to neutralize the charge amount detected by the charge amount detecting means;
The sheet conveying apparatus according to claim 1, wherein the sheet conveying apparatus is a sheet conveying apparatus. Stacking means for stacking sheets after the charge is applied by the charge applying means;
A second charge amount detection means for detecting the charge amount of the sheet after the charge application stacked on the stacking means;
Correction means for correcting the charge amount detected by the charge amount detection means based on the charge amount detected by the second charge amount detection means;
The sheet conveying apparatus according to claim 4. The charge applying unit includes a first charge applying unit that applies a positive charge and a second charge applying unit that applies a negative charge to the sheet conveyed by the sheet conveying unit, and the first charge A charge is imparted to the sheet by any one of the imparting unit and the second charge imparting unit.
The sheet conveying apparatus according to claim 1, wherein the sheet conveying apparatus is a sheet conveying apparatus. The member in contact with the sheet transported by the sheet transporting means in the charge applying means is easily charged based on at least one of the charging property of the sheet and the charging state of the sheet transported by the sheet transporting means. It is made of a material selected from the electrification row representing the order,
The sheet conveying apparatus according to claim 1, wherein the sheet conveying apparatus is a sheet conveying apparatus. The member in contact with the sheet conveyed by the sheet conveying unit in the charge applying unit is formed in a roller shape, and the sheet is conveyed by rotation of the member.
The sheet conveying apparatus according to claim 1, wherein the sheet conveying apparatus is a sheet conveying apparatus. An image forming unit for forming an image on a sheet;
An image forming apparatus comprising: a sheet conveying device that conveys a sheet on which an image is formed in the image forming unit;
The sheet conveying apparatus is the sheet conveying apparatus according to any one of claims 1 to 8,
An image forming apparatus.

Images