JP2019104608A - Electrostatic adsorption belt, sheet feeding device and image forming device - Google Patents

Abstract

To provide an electrostatic adsorption belt which is suitable for using in a sheet feeding device utilizing looseness of the electrostatic adsorption belt and easy to manufacture, and to provide the sheet feeding device provided with the electrostatic adsorption belt, and an image forming device provided with the sheet feeding device.SOLUTION: Related to an electrostatic adsorption belt 200, in at least one end part side in a width direction of the belt 200, a region for performing power feeding to a power feeding part 412 of an electrode pattern 400 has a first power feeding region 291 on a most end part side in the width direction and a second power feeding region 291 inner than the first power feeding region 291 in the width direction, and in at least the one end part side, a plurality of the power feeding parts 412 have a plurality of first power feeding parts 412 arranged in the first power feeding region and at least one second power feeding part 412a which is adjacent to the upstream side in a movement direction of the belt 200 of a sticking part 270 and is arranged in the second power feeding region 292 containing what is nearest to the sticking part 270.SELECTED DRAWING: Figure 16

Description

  The present invention is provided with an electrostatic adsorption belt used in a sheet feeding apparatus for feeding sheets using electrostatic adsorption force, a sheet feeding apparatus provided with the electrostatic adsorption belt, and the sheet feeding apparatus. The present invention relates to an image forming apparatus.

  2. Description of the Related Art Conventionally, an image forming apparatus such as a copying machine, a printer, or a facsimile machine includes a sheet feeding device for feeding a sheet. The sheet feeding apparatus is a friction feeding method in which the uppermost sheet is separated from the cassette on which the sheet bundle is stacked by using a frictional force of a rubber roller or the like and is fed (hereinafter, also simply referred to as "separate feeding"). There is In this friction feeding type sheet feeding apparatus, the uppermost sheet is fed by rotating while pressing a rubber roller against a sheet bundle. In this way, when the sheets are fed out, so-called double feeding of sheets may occur, in which a plurality of sheets are conveyed by friction between the sheets. Therefore, it has been practiced to feed only the uppermost sheet by exerting a transport resistance on the other than the uppermost sheet by means of a separation pad or a retard roller.

  In such a friction separation type sheet feeding apparatus, since the sheet is fed while applying a large pressure to the sheet by the rubber roller, noise is generated due to the rubbing between the sheet and the sheet and the rubber roller. Further, when the double feeding of the sheets is prevented by the separation pad or the retard roller, a sliding noise between the sheets is generated largely. In addition, since the separation pad and the retard roller serve as the transport resistance for the top sheet even when the double feeding of the sheet is not generated, the sound due to the stick-slip between the separation pad or the retard roller and the sheet is generated Do.

  Therefore, as a solution to the problem of the noise, there is a sheet feeding apparatus for feeding a sheet by using an electrostatic adsorption force. The sheet feeding apparatus separates and feeds the sheet while adsorbing the sheet by an electric field formed on the surface of the electrostatic attraction belt. In particular, in the sheet feeding apparatus of the system in which the sheet is separated and fed by utilizing the slack (deflection) of the electrostatic adsorption belt, since the uppermost sheet can be conveyed so as to be separated from the sheet bundle, noise is reduced. It can be significantly reduced.

  The electrode patterns of the electrostatic attraction belt used in the sheet feeding apparatus using electrostatic attraction are as follows.

  Patent Document 1 describes an electrostatic attraction belt having a feeding portion formed obliquely to the width direction of the electrostatic attraction belt, and having an electrode pattern continuous over the entire circumference of the electrostatic attraction belt. Patent Document 1 does not describe a method for producing this electrostatic attraction belt. However, the electrostatic attraction belt described in Patent Document 1 is manufactured by a method of forming an electrode pattern on a flat sheet-like base layer and bonding the opposing end portions of the base layer to form a cylindrical shape. Is very difficult.

  Further, in Patent Document 2, all the electrode patterns are independent, each electrode pattern has a feeding portion, and only the electrode pattern in contact with a brush for feeding generates an electrostatic force. An electrostatic attraction belt is described. Patent Document 2 does not describe a method of producing the electrostatic attraction belt. However, the electrostatic adsorption belt described in Patent Document 2 is manufactured by a method of forming an electrode pattern on a flat sheet-like base layer and bonding the opposing end portions of the base layer to form a cylindrical shape. It can be considered that

  Further, Patent Document 3 has a pattern for feeding common to all electrode patterns, and electrostatic attraction is configured to generate electrostatic force over the entire circumference of the electrostatic attraction belt by feeding electricity from one place at a time. A belt is described. Patent Document 3 does not describe a method of manufacturing the electrostatic attraction belt. However, it is considered that the electrode pattern can be formed on a flat sheet-like base layer described in Patent Document 3, and the opposing end portions of the base layer can be bonded to make a cylindrical shape.

JP, 2016-44028, A JP, 2002-104684, A Unexamined-Japanese-Patent No. 6-255823

  However, the electrostatic attraction belt described in Patent Document 2 is difficult to apply to a sheet feeding apparatus that utilizes the slack of the electrostatic attraction belt because electrostatic force is generated only at the contact portion such as a feeding brush. . This is because, as will be described later in detail, in the sheet feeding apparatus utilizing the slack of the electrostatic adsorption belt, stable power feeding is substantially possible only from the roller portion.

  Further, in the electrostatic adsorption belt described in Patent Document 3, as described later in detail, in order to discharge the surface of the electrostatic adsorption belt, the feeding is stopped every time one sheet is fed. The throughput is reduced because it is necessary to make the electrostatic adsorption belt make one revolution.

  On the other hand, the above-described electrode pattern of the electrostatic attraction belt described in Patent Document 1 is suitable for a sheet feeding apparatus that utilizes the slack of the electrostatic attraction belt. This is because, as will be described later in detail, in the sheet feeding apparatus utilizing the slack of the electrostatic adsorption belt, stable power feeding is substantially possible only from the roller portion. However, as described above, the electrostatic attraction belt described in Patent Document 1 forms an electrode pattern on a flat sheet-like base layer and bonds opposing ends of the base layer to form a cylindrical shape. It is very difficult to manufacture with a relatively easy and inexpensive manufacturing method. Instead, a special and relatively expensive method of forming an electrode pattern on the inner peripheral surface side and the outer peripheral surface side of the cylindrical base layer is considered to be necessary.

  Accordingly, an object of the present invention is to provide an electrostatic adsorption belt which is suitable for use in a sheet feeding apparatus utilizing the slack of the electrostatic adsorption belt and which is easy to manufacture, a sheet feeding apparatus provided with the electrostatic adsorption belt, It is an object of the present invention to provide an image forming apparatus provided with the sheet feeding device.

  The above object can be achieved by the electrostatic attraction belt, the sheet feeding apparatus and the image forming apparatus according to the present invention. In summary, the present invention includes a base layer, an electrode pattern provided on the base layer, and a bonding portion in which opposing ends of the base layer are bonded to each other, and a voltage is applied to the electrode pattern. A flexible endless electrostatic adsorption belt for adsorbing and transporting a sheet by being moved in the circumferential direction, wherein the electrode patterns are spaced apart from each other in the circumferential direction, A plurality of suction portions formed on the outer peripheral surface of the base layer so as to extend in the width direction orthogonal to the direction, and the end portions disposed alternately on the opposite end side in the width direction in the circumferential direction A plurality of feed parts formed on the inner circumferential surface of the base layer so as to be connected to each of the plurality of suction parts on the side, and the feed part is the suction to which the feed part is connected Upstream of the moving direction from the unit It is formed to extend, and at least at one end side in the width direction, a region where power feeding to the power feeding portion is performed is a first power feeding region at the most end side in the width direction, and the first power feeding A second feed region on the inner side in the width direction than the region, and on the at least one end side, the plurality of feed portions are a plurality of first feed portions disposed in the first feed region And at least one second power feeding portion disposed in the second power feeding region including one closest to the bonding portion, which is close to the upstream side in the moving direction of the bonding portion. It is an electrostatic attraction belt that is characterized.

  According to another aspect of the present invention, the stacking means on which the sheets are stacked, the first rotating body disposed above the stacking means, and the downstream side of the first rotating body in the sheet conveying direction The inner surface is supported by the provided second rotating body, the first rotating body, and the second rotating body, and the sheet stacked on the loading means is adsorbed and conveyed, and has flexibility. An electrostatic adsorption belt in the form of an endless belt, and a power source for applying a voltage to an electrode pattern provided on the electrostatic adsorption belt, wherein the electrostatic force is applied between the first rotating body and the second rotating body A sheet feeding apparatus for adsorbing and conveying a sheet by forming a slack of an adsorption belt, wherein the electrostatic adsorption belt is the electrostatic adsorption belt of the present invention. Be done.

  According to another aspect of the present invention, there is provided an image forming unit comprising: an image forming section for forming an image on a sheet; and the sheet feeding apparatus according to the present invention for feeding a sheet to the image forming section. An apparatus is provided.

  According to the present invention, an electrostatic adsorption belt suitable for use in a sheet feeding apparatus utilizing the slack of the electrostatic adsorption belt and easy to manufacture, a sheet feeding apparatus provided with the electrostatic adsorption belt, and a sheet thereof An image forming apparatus having a feeding device can be provided.

1 is a schematic cross-sectional view of an image forming apparatus. FIG. 2 is a schematic cross-sectional view of a sheet feeding device. It is a schematic diagram of the electrostatic attraction | suction belt of a package electric power feeding pattern. It is a schematic diagram which shows the electric power feeding state of the electrostatic attraction | suction belt of a package electric power feeding pattern. FIG. 2 is a control block diagram of a sheet feeding apparatus. FIG. 6 is a schematic view for explaining a feeding operation. It is a schematic diagram for demonstrating the static elimination of the surface of an electrostatic adsorption belt. It is a schematic diagram for demonstrating the static elimination of the electrostatic adsorption belt of a package electric power feeding pattern. It is a schematic diagram for demonstrating the ideal electric power feeding state to an electrostatic adsorption belt. It is a schematic diagram of the electrostatic adsorption belt of a partial electric power feeding pattern. It is a schematic diagram which shows the electric power feeding state of the electrostatic attraction | suction belt of a partial electric power feeding pattern. It is a schematic diagram which shows the static elimination state of the electrostatic adsorption belt of a partial electric power feeding pattern. It is a schematic diagram which shows the manufacturing method of the electrostatic attraction | suction belt of a package electric power feeding pattern. It is a schematic diagram for demonstrating the subject in manufacture of the electrostatic attraction | suction belt of a partial electric power feeding pattern. It is a top view of a part of electrostatic adsorption belt for explaining a subject in manufacture of an electrostatic adsorption belt of a partial electric supply pattern. FIG. 2 is a plan view of a portion of the electrostatic attraction belt of Example 1; FIG. 10 is a plan view of a portion of the electrostatic attraction belt of Example 2; FIG. 16 is a plan view of a portion of the electrostatic attraction belt of Example 3;

  Hereinafter, the electrostatic attraction belt, the sheet feeding apparatus, and the image forming apparatus according to the present invention will be described in more detail with reference to the drawings.

Example 1
1. Image Forming Apparatus FIG. 1 is a schematic cross-sectional view of an image forming apparatus 100 of the present embodiment. The image forming apparatus 100 of the present embodiment is a tandem type copying machine adopting an intermediate transfer method capable of forming a full color image using an electrophotographic method.

  An image reading unit 41 including an image sensor or the like that irradiates light onto a document placed on a platen glass as a document placement table and converts reflected light into a digital signal on the top of the device body 100A of the image forming apparatus 100. It is provided. The document is conveyed onto the platen glass by the automatic document feeder 41a. In the apparatus main assembly 100A, the image forming unit 55, the sheet feeding devices 51 and 52 for feeding the sheet S to the image forming unit 55, and the sheet reversing unit for inverting the sheet S and conveying it to the image forming unit 55 59 are provided. Although two sheet feeding devices 51 and 52 are provided in the image forming apparatus 100 of the present embodiment, the configuration and operation of these are substantially the same. Therefore, in the following description, the sheet feeding device 51 on the upper side in FIG. 1 will be mainly described, and the description on the sheet feeding device 52 on the lower side in FIG. 1 will be appropriately omitted.

  The image forming unit 55 includes an exposure unit 42, and four process cartridges 43Y, 43M, 43C, which form toner images of respective colors of yellow (Y), magenta (M), cyan (C) and black (K). It has 43K. The image forming unit 55 further includes an intermediate transfer unit 44 disposed above the four process cartridges 43Y, 43M, 43C, and 43K, a secondary transfer unit 56, and a fixing unit 57. For elements having the same or corresponding functions or configurations provided for each color of yellow, magenta, cyan, and black, Y and M at the end of the reference numerals indicating that they are elements provided for each color , C and K may be abbreviated and explained in a general way.

  The process cartridge 43 includes a photosensitive drum 21, a charging roller 22, a developing device 23, and a cleaning device 24. The intermediate transfer unit 44 has an intermediate transfer belt 25. The intermediate transfer belt 25 is stretched around a plurality of stretching rollers including a belt drive roller 26 and a secondary transfer inner roller 56a. On the inner peripheral surface side of the intermediate transfer belt 25, primary transfer rollers 27 that abut on the respective photosensitive drums 21 via the intermediate transfer belt 25 are arranged. The secondary transfer portion 56 is configured of a secondary transfer inner roller 56 a and a secondary transfer outer roller 56 b that abuts against the secondary transfer inner roller 56 a via the intermediate transfer belt 25. The fixing unit 57 includes a fixing roller 57a and a fixing backup roller 57b. The sheet feeding device 51 includes a cassette 51a, a feeding portion 51b, and a pair of drawing rollers 51c and 51d. Similarly, the sheet feeding device 52 on the lower side in FIG. 1 also includes a cassette 52a, a feeding portion 52b, and a pair of drawing rollers 52c and 52d.

  Further, the apparatus main assembly 100A is provided with a conveyance path 103 before secondary transfer for conveying the sheet S fed from the cassettes 51a and 52a to the secondary transfer unit 56. Further, the apparatus main assembly 100A is provided with a pre-fixing conveyance path 104 for conveying the sheet S conveyed to the secondary transfer unit 56 from the secondary transfer unit 56 to the fixing unit 57. Further, the post-fixing conveyance path 105 for conveying the sheet S conveyed to the fixing unit 57 from the fixing unit 57 to the switching member 61 and the sheet S conveyed to the switching member 61 are discharged from the switching member 61 to the apparatus body 100A. And a discharge path 106 for conveying to the portion 58. Further, in the apparatus body 100A, the sheet S reversed by the sheet reversing unit 59 is conveyed to the image forming unit 55 again in order to form an image on the back side of the sheet S on which an image is formed on one side by the image forming unit 55. A reconveying path 107 is provided.

  The image forming operation of the image forming apparatus 100 of this embodiment will be described. When the image forming operation is started, the photosensitive drum 21 and the intermediate transfer belt 25 are rotationally driven. The photosensitive drum 21 rotates in the clockwise direction in the drawing, and the intermediate transfer belt 25 rotates in the counterclockwise direction in the drawing (rotational movement, circulation movement). The surface of the rotating photosensitive drum 21 is uniformly charged to a predetermined potential of a predetermined polarity by the charging roller 22. The surface of the charged photosensitive drum 21 is scanned and exposed by the exposure unit 42 to form an electrostatic image (electrostatic latent image) on the photosensitive drum 21. The exposure unit 42 irradiates the surface of the photosensitive drum 21 with a laser beam based on image information from an external device (not shown) such as a personal computer or the like and the document reading unit 41. As a result, the charge on the portion of the photosensitive drum 21 irradiated with the laser beam is attenuated, whereby an electrostatic image is formed on the photosensitive drum 21. The electrostatic image formed on the photosensitive drum 21 is supplied with toner as a developer by the developing device 23 and developed (visualized) to form a toner image on the photosensitive drum 21. In this embodiment, in the image area (exposed area) on the photosensitive drum 21 which has been uniformly charged and then exposed to light, the charge polarity of the photosensitive drum 21 is the same (image area). In the embodiment, the negatively charged toner adheres. The toner image formed on the photosensitive drum 21 is transferred (primary transfer) onto the rotating intermediate transfer belt 25 by the primary transfer roller 27. During the primary transfer process, a primary transfer bias having a polarity (positive in this embodiment) opposite to the charging polarity (normal charging polarity) of the toner during development is applied to the primary transfer roller 27. For example, when forming a full color image, toner images of yellow, magenta, cyan, and black formed on the photosensitive drums 21 are sequentially transferred onto the intermediate transfer belt 25 in a superimposed manner.

  On the other hand, in parallel with the toner image forming operation, only one sheet S is separated and fed from the cassette 51 a by the feeding portion 51 b of the sheet feeding device 51. The sheet S arrives at the drawing roller pair 51c, 51d. The sheet S is nipped and conveyed by the pair of drawing rollers 51 c and 51 d, and is fed to the conveyance path 103. Further, the position of the leading end of the sheet S is adjusted by coming into contact with the stopped registration roller pair 62a, 62b. Further, the registration roller pair 62 a and 62 b is driven at timing when the position of the toner image on the intermediate transfer belt 25 matches the position of the sheet S in the secondary transfer portion 56, and the sheet S reaches the secondary transfer portion 56. It is transported. Then, in the secondary transfer portion 56, the toner image on the intermediate transfer belt 25 is transferred onto the sheet S (secondary transfer). At the time of the secondary transfer process, a secondary transfer bias having a reverse polarity to the charging polarity of the toner at the time of development is applied to the secondary transfer outer roller 56b.

  The sheet S on which the toner image has been transferred is conveyed to the fixing unit 57. Then, the sheet S is nipped and conveyed by the fixing roller 57a and the fixing backup roller 57b in the fixing unit 57, whereby the toner image on the sheet S is heated and pressed. As a result, the toner is melted and mixed under heat and pressure, and is fixed on the sheet S as a full color image.

  The sheet S on which the image is fixed is discharged (outputted) to the outside of the apparatus main body 100A by a discharge unit 58 provided downstream of the fixing unit 57. When an image is formed on both sides of the sheet S, the conveying direction of the sheet S is reversed by the sheet reversing unit 59, and the sheet S is conveyed to the image forming unit 55 again.

2. Schematic Configuration of Sheet Feeding Device Next, a schematic configuration of the sheet feeding device 51 of the present embodiment will be described. FIG. 2 is a schematic cross-sectional view of the vicinity of the sheet feeding device 51 (a cross section approximately orthogonal to the rotation axis direction of the first and second pinching and conveying roller pairs 201 and 202 described later).

  The sheet feeding device 51 according to the present embodiment feeds a sheet (recording material, transfer material) S, which is typically a sheet, using electrostatic attraction. The sheet feeding device 51 includes a cassette 51 a as a storage unit that stores the sheet S. Further, the sheet feeding device 51 includes a feeding unit 51b as a sheet suction and separation feeding unit that separates and transports the sheets S stored in the cassette 51a one by one while adsorbing the sheets S by static electricity. Further, the sheet feeding device 51a includes a pair of drawing rollers 51c and 51d as conveying means for holding and conveying the sheet S separated and conveyed one by one from the cassette 51a by the feeding unit 51b. A control unit 70 shown in FIG. 5 described later is electrically connected to each portion of the sheet feeding device 51.

  The cassette 51a includes an intermediate plate 301a capable of moving up and down the sheet S, an elevating device 301 as elevating means for moving up and down the intermediate plate 301a, and detection means for detecting the upper surface position of the sheet S stacked on the intermediate plate 301a. The seat surface height detection unit 302 is provided. The middle plate 301 a is an example of a stacking unit on which the sheets S are stacked. The lifting device 301 includes a lifter 301b rotatably provided below the middle plate 301a, and the uppermost sheet S1 stacked on the middle plate 301a and the middle plate 301a according to the rotation angle of the lifter 301b. Change the position of.

  The sheet surface height detection unit 302 is disposed above the middle plate 301a, and includes a sensor flag 302a and a photo sensor 302b. The sensor flag 302a is rotatably supported by a support portion (not shown), and one end is disposed at a position where it can contact the top surface of the top sheet S1, and the other end is disposed at a position where the photosensor 302b can be shielded. It is done. When the top surface of the uppermost sheet S1 is positioned at a predetermined height, the sensor flag 302a is rotated and the photosensor 302b is shielded from light. A control unit 70 shown in FIG. 5 described later detects the light blocking state of the photo sensor 302 b to detect the position of the top surface of the uppermost sheet S 1. Then, the control unit 70 controls the operation of the lifting device 301 so that the upper surface of the uppermost sheet S1 is always detected by the sheet surface height detection unit 302, and the position of the middle plate 301a becomes the uppermost sheet S1. Maintain the position where the height of the upper surface becomes almost constant.

  The feeding unit 51 b includes a feeding unit frame (not shown) supporting the first pinching and conveying roller pair 201, the second pinching and conveying roller pair 202, and the first and second pinching and conveying roller pairs 201 and 202. Is equipped. Further, the feeding portion 51b is an electrostatic attraction belt (hereinafter simply referred to as “belt”) which is an endless attraction member having flexibility which is pinched and conveyed by the first and second pinching and conveying roller pairs 201 and 202, respectively. Also referred to as "). Furthermore, the feeding unit 51 b generates a driving force for driving the first holding motor roller 203 as a first driving unit that generates a driving force for driving the first holding conveyance roller pair 201, and a second holding conveyance roller pair 202. And a second drive motor 204 as a second drive unit. The configuration of the feeding portion 52b provided in the lower sheet feeding device 52 in FIG. 1 is the same as the configuration of the feeding portion 51b provided in the upper sheet feeding device 51 in FIG.

  The first pinching and conveying roller pair 201 is disposed downstream of the second pinching and conveying roller pair 202 in the conveying direction of the sheet S, and the first pinching and conveying inner roller (second rotating body) 201 a and the first pinching and conveying And an outer roller 201b. The first nipping / conveying inner roller 201a is rotatably supported by a shaft supporting member (not shown) disposed on the inner peripheral surface side of the belt 200 and having a fixed arrangement position, and from the first drive motor 203 Drive force is transmitted via drive transmission means (not shown). Further, the first nipping and conveying inner roller 201a is disposed with a gap Lr1 to the upper surface of the uppermost sheet S1. The first nipping and conveying outer roller 201b, which is a driven rotating member, is disposed to face the first nipping and conveying inner roller 201a with the endless belt 200 interposed therebetween, and is rotatably supported by a shaft supporting member (not shown) It is done. The first pressing spring 201 c is connected to the shaft support member. Then, the first nipping and conveying outer roller 201b is biased in the axial center direction of the first nipping and conveying inner roller 201a by the first pressing spring 201c, and holds the belt 200 together with the first nipping and conveying inner roller 201a.

  The second nipping / conveying roller pair 202 is configured of a second nipping / conveying inner roller (first rotating body) 202 a and a second nipping / conveying outer roller 202 b. The second nipping / conveying inner roller 202a is rotatably supported by a shaft supporting member (not shown) disposed on the inner peripheral surface side of the belt 200 and having a fixed arrangement position, and from the second drive motor 204 Drive force is transmitted via drive transmission means (not shown). Further, the second pinching and conveying inner roller 202a is disposed with a gap Lr2 to the upper surface of the uppermost sheet S1. The second pinching and conveying outer roller 202b, which is a driven rotating member, is disposed to face the second pinching and conveying inner roller 202a with the belt 200 interposed therebetween, and is rotatably supported by a shaft support member (not shown) . A second pressing spring 202c is connected to the shaft support member. The second pinching and conveying outer roller 202b is urged in the axial center direction of the second pinching and conveying inner roller 202a by the second pressing spring 202c to pinch the belt 200 together with the second pinching and conveying inner roller 202a.

A gap Lr1 between the first nipping and conveying inner roller 201a and the upper surface of the uppermost sheet S1 and a gap Lr2 between the second nipping and conveying inner roller 202a and the upper surface of the uppermost sheet S1 are expressed by the following formulas.
Lr1 ≧ Lr2
Have a relationship of Therefore, the feeding unit 51 b is disposed with respect to the sheet S at the disposition angle θu. The disposition angle θu is an angle formed by a straight line passing through the rotation center of the first nipping and conveying inner roller 201a and the rotation center of the second nipping and conveying inner roller 202a and the surface of the sheet S stacked on the middle plate 301a. . By disposing the feeding unit 51b in this manner, the sheet S can be adsorbed and separated and fed so as to turn up the sheet S. Therefore, a force to separate the sheet S can be effectively generated.

  The endless belt 200 has an inner surface formed by first and second nipping / conveying inner rollers 201a and 202a, which are rotating members (rotating members) provided in plurality (two in the present embodiment) along the conveying direction of the sheet S. It is supported. The circumferential length of the belt 200 is “twice of the distance between the centers of rotation of the first nipping / conveying inner roller 201 a and the second nipping / conveying inner roller 202 a” and “the outer peripheral surface of each of the rollers 201 a and 202 a It has a length longer than the length which added "half of perimeter" and. That is, the circumferential length of the belt 200 is set with a margin (in order to form a slack) than the winding shortest circumferential length of the feeding portion 51b. Therefore, the belt 200 can sag downward while rotating (moving) by the rotation of the first and second nipping and conveying inner rollers 201a and 202a. As a result, even if the gaps Lr1 and Lr2 exist between the first and second nipping and conveying inner rollers 201a and 202a and the uppermost sheet S1 of the sheets S stacked on the middle plate 301a, the belt 200 can , Can be in contact with the top sheet S1.

  Here, in the present embodiment, when the sheet S is separated and fed, the sheet S is attracted to the belt 200 by static electricity so as to suppress rubbing between the sheets S, and then the belt 200 is elastically deformed upward. By pulling up, the sheet S is separated from the other sheets S. In the present embodiment, the circumference of the belt 200 is secured so that the contact area Mn between the belt 200 and the sheet S can be obtained, which can obtain the adsorptive power to the sheet S necessary to separate and feed the sheet S in this manner. The length has been determined. Further, as described later in detail, the belt 200 is provided with a first power supply 205a which is a positive power supply as positive voltage supply means for supplying a positive voltage and a negative voltage supply means for supplying a negative voltage. The second power supply 205b, which is a negative power supply, is electrically connected. Then, an electrostatic attraction force (electrostatic attraction force) that attracts the sheet S is generated on the belt 200 by the positive voltage and the negative voltage supplied from the first and second power supplies 205a and 205b, respectively.

  The first and second drive motors 203 and 204 are connected to a sheet separation control unit 210 built in a control unit 70 shown in FIG. 5 described later. The first drive motor 203 transmits the driving force to the first nipping and conveying inner roller 201a, and the second driving motor 204 transmits the driving force to the second nipping and conveying inner roller 202a. The first and second drive motors 203 and 204 perform cooperative operations by receiving the individual speed command pulse trains transmitted from the sheet separation control unit 210, and the optimum operation according to the type of the sheet S to be fed. The separation operation of the sheet S is performed.

  The sheet feeding device 51 is provided with a charge removing member 303 as a charge removing unit for removing the charge on the surface of the belt 200. The static elimination member 303 is made of a conductive brush, a conductive non-woven fabric, or the like. In this embodiment, a discharging brush composed of a conductive brush is used as the discharging member 303. The discharging brush 303 is connected (electrically grounded) to the GND potential, and is installed in contact with the surface of the belt 200. The need to discharge the surface of the belt 200 will be described later.

3. Principle of Generation of Suction Force Next, a principle of generation of the suction force for the belt 200 to suction the sheet S will be described. FIG. 3A is a schematic plan view showing the surface of the belt 200 (the electrode pattern 400 provided inside the belt 200 is also shown). FIG. 3B is a schematic perspective view of the belt 200 (an electrode pattern 400 provided inside the belt 200 is also shown). Further, FIG. 3C is a schematic cross-sectional view of the feeding portion of the belt 200. FIG. 3D is a schematic view showing the concept of the electrostatic attraction force acting between the belt 200 and the sheet S. As shown in FIG. Here, unlike the belt 200 according to the present invention, the case of using the belt 200 of “collective power feeding pattern” in which power feeding to the electrode pattern is collectively performed over the entire circumference of the belt 200 will be described as an example.

  As shown in FIG. 3, the belt 200 includes a belt main body (base material) 200 </ b> A and an electrode pattern 400 provided on the belt main body 200 </ b> A. The electrode pattern 400 includes a first electrode portion 401 and a second electrode portion 402. A plurality of first electrode portions 401 are spaced apart from each other in the circumferential direction of the belt 200, and a plurality of suction portions 411 extending substantially parallel to the width direction of the belt 200; And a feed unit 412 connected to the suction unit 411 of Similarly, the second electrode unit 402 includes a plurality of suction units 421 and a feed unit 422. The width direction of the belt 200 is a direction orthogonal to the conveyance direction of the belt 200 (moving direction of the surface). As described above, the suction portions 411 and 421 of the first and second electrode portions 401 and 402 have a comb-tooth shape, and the suction portion 411 of the first electrode portion 401 and the suction portion 421 of the second electrode portion 402 are They are alternately arranged in the circumferential direction of the belt 200. The feeding parts 412 and 422 of the first and second electrode parts 401 and 402 are disposed in the vicinity of the opposite end of the belt 200 in the width direction. The suction units 411 and 421 are disposed inside the belt main body 200A. The feed parts 412 and 422 are disposed inside the belt body 200A, and a part thereof is exposed on the inner peripheral surface side of the belt body 200A.

The belt main body 200A is made of, for example, polyimide which is a dielectric having a volume resistivity of 10 ⁸ Ωcm or more, and the layer thickness thereof is about 100 μm. The first and second electrode portions 401 and 402 are made of, for example, a metal (for example, copper) which is a conductor having a volume resistivity of 10 ⁶ Ωcm or less, and the layer thickness thereof is about 10 μm. As described later, the belt main body 200A is formed by forming the electrode pattern 400 on the base layer and forming the dielectric layer so as to cover the electrode pattern 400 (to expose a part of the feeding portion). Can. The material and thickness of the belt 200 are adjusted so that the belt 200 sags downward to form a barrel shape when the belt 200 approaches the sheet S, and the belt 200 has appropriate elasticity.

  On the inner circumferential surfaces of the belt 200 facing the first and second pinching and conveying inner rollers 201a and 202a, parts of the feeding portions 412 and 422 of the first and second electrode portions 401 and 402 are exposed. Then, the first contact point 206a connected to the first power supply (positive power supply) 205a is in contact with the feeding portion 412 of the first electrode portion 401, and the feeding portion 422 of the second electrode portion 402 The second contact 206b connected to the negative power supply 205b is in contact.

  For example, a positive voltage of about +1 kV is applied to the first electrode portion 401. In addition, a negative voltage of, for example, about −1 kV is applied to the second electrode unit 402. The first and second contacts 206a and 206b have a structure in which a carbon brush is fixed to the end of a metal plate having elasticity by caulking, for example. The carbon brushes of the first and second contact points 206a and 206b are in contact with the feeding parts 412 and 422 of the first and second electrode parts 401 and 402, respectively. Since the first and second contact points 206a and 206b have elasticity, they can follow and contact the belt 200 whose cross-sectional shape changes.

  As shown in FIG. 3D, when a positive voltage and a negative voltage are applied to the first and second electrode portions 401 and 402, respectively, adsorption of the first and second electrode portions 401 and 402 to which the voltage is applied is performed. By the portions 411 and 421, an uneven electric field is formed in the vicinity of the surface of the belt 200. Then, when the belt 200 in which such an uneven electric field is formed approaches the sheet S, dielectric polarization occurs in the surface layer of the sheet S which is a dielectric, and the stress between Maxwell causes the belt 200 to be between the sheet S. An electrostatic attraction occurs on the

  In the above description, the first and second contacts 206a and 206b are in direct contact with the feed parts 412 and 422 of the electrode pattern 400, but the first and second contacts 206a and 206b are feed parts 412 and 422, respectively. It can be in contact with the power supply member in direct contact. That is, in the sheet feeding device 51 using the slack of the belt 200, the belt 200 sags as described in detail later. Therefore, the portion in which the belt 200 is nipped by the first nipping / conveying roller pair 201 or the second nipping / conveying roller pair 202 is the portion that contacts the belt 200 most stably and a stable electrical connection is obtained. Therefore, power can be supplied from the second nipping / conveying inner roller 202a to the electrode pattern 400 of the belt 200 at the portion where the belt 200 is nipped by the second nipping / conveying roller pair 202. FIG. 4A is a schematic perspective view of the second pinching and conveying inner roller 202a. FIG. 4B is a developed view of the belt 200 shown in FIG. 3 when viewed from the inner peripheral surface side (a suction portion 411 and 421 provided inside the belt 200 is also shown) showing how the electrode pattern 400 is fed. It is). As shown in FIG. 4A, the first feed roller 501 as a first feed member and the second feed roller as a second feed member are provided at both ends of the second pinching and conveying inner roller 202a in the rotation axis direction. And 502 are provided. As shown in FIG. 4B, the first power supply roller 501 and the second power supply roller 502 are in contact with the power supply portions 412 and 422 of the electrode pattern 400 exposed on the inner peripheral surface of the belt 200, respectively. Further, the first contact point 206a and the second contact point 206b described above are in contact with the first power feeding roller 501 and the second power feeding roller 502, respectively. As a result, the first and second power supplies 205a and 205b are electrically connected to the suction portions 411 and 421 of the electrode pattern 400. As described above, in the belt 200 shown in FIG. 3, for example, the first and second feed rollers 501 and 502 at both ends of the second nipping / conveying inner roller 202a are collectively used as an electrode pattern 400 across the entire circumference of the belt 200 as contacts. Voltage is applied.

4. Control Mode Next, a control mode of the sheet feeding device 51 will be described. FIG. 5 is a control block diagram of the sheet feeding device 51 in the present embodiment.

  The image forming apparatus 100 includes a control unit 70 as a control unit. The control unit 70 is connected to a first drive motor 203, a second drive motor 204, a first power supply (positive power supply) 205a, a second power supply (negative power supply) 205b, a seat surface height detection unit 302, a timer 71 and the like. ing.

  Further, the control unit 70 incorporates a sheet separation control unit 210 as a subsystem. The sheet separation control unit 210 transmits the velocity command pulse train to the first and second drive motors 203 and 204 by a table Mt1 (not shown) stored in the built-in storage area of the sheet separation control unit 210. Details of a control method of the first and second drive motors 203 and 204 by the sheet separation control unit 210 will be described later.

5. Next, the feeding operation of the sheet S by the feeding unit 51b will be described. In the feeding operation, the belt 200 can be sequentially moved to the next positions from the standby position separated from the sheet S stacked on the middle plate 301a. First, the suction position is a suction position at which the sheet S is adsorbed by surface contact while elastically deforming the sheet S stacked on the middle plate 301 a. Next, it is a separation position where the adsorbed sheet S is moved upward to separate it from the sheet S below while eliminating bending. Next, it is a separation position where the adsorbed sheet S separates. This will be described in more detail below.

  6 (a) to 6 (f) are schematic diagrams showing the feeding operation of the sheet S by the feeding unit 51b in time series. The feeding operation of the sheet S by the feeding unit 51b is performed in the order of time series, the initial operation, the approaching operation, the contact area increasing operation, the suction operation, the separating operation, and the conveying operation shown in FIGS. It consists of two steps. Hereinafter, each of these steps will be described in order. Here, unlike the case where the belt 200 according to the present invention is used, positive voltage and negative voltage are applied to the electrode pattern 400 (for example, the electrode pattern of FIG. 3) of the belt 200 in all the above steps. The case where the electrostatic adsorption force is generated will be described as an example.

  The initial operation shown in FIG. 6A is an operation of arranging the belt 200 at an initial position (standby position) of the feeding operation. In this initial operation, the control unit 70 separates the belt 200 from the uppermost sheet S1 by a predetermined gap Lr2, and stops the first and second drive motors 203 and 204.

  The approaching operation shown in FIG. 6B is an operation for deforming the belt 200 into a barrel shape by slackening downward and causing the suction surface side of the belt 200 to approach the uppermost sheet S1. In this approaching operation, the control unit 70 causes the second drive motor 204 to rotate the second pinching and conveying roller pair 202 in the direction of the arrow in the drawing at the rotational speed U2a. Also, at the same time, the control unit 70 causes the first nipping / conveying roller pair 201 to stop or causes the first driving motor 203 to rotate the first nipping / conveying roller pair 201 at a rotational speed slower than the rotational speed U2a. . Thereby, the control unit 70 conveys the belt 200 in the direction of the arrow Ad in the drawing, and deforms the belt 200 into a barrel shape. Then, the belt 200 is deformed into a barrel shape in this manner, whereby the surface of the belt 200 comes in contact with the uppermost sheet S1.

  In the contact area increasing operation shown in FIG. 6C, the surface of the belt 200 moved to the position for adsorbing the sheet S (adsorption position) and the uppermost sheet S1 by continuing the above-described approach operation. This is an operation to increase the contact area Mc. In this operation, the control unit 70 causes the second drive motor 204 to rotate the second nipping / conveying roller pair 202 in the direction of the arrow in the drawing at the rotational speed U2a, as in the approaching operation. Also, at the same time, the control unit 70 causes the first nipping / conveying roller pair 201 to stop or causes the first driving motor 203 to rotate the first nipping / conveying roller pair 201 at a rotational speed slower than the rotational speed U2a. . Thereby, the control unit 70 conveys the belt 200 in the direction of the arrow Ad in the drawing to increase the contact area Mc. The control unit 70 continues the contact area increasing operation until the contact area Mc becomes equal to the predetermined contact area Mn. Here, detection means for directly detecting the size of the contact area Mc may be provided, but in the present embodiment, the first and second pinching and conveying roller pairs based on the time measurement of the size of the contact area Mc by the timer 71 are provided. It is alternatively detected by the difference in the transport amount between 201 and 202.

  In the suction operation shown in FIG. 6D, the uppermost sheet S1 is adsorbed to the belt 200 in a state where the upper surface of the uppermost sheet S1 and the surface of the belt 200 are in surface contact with each other at a predetermined contact area Mn. It is. When the uppermost sheet S1 contacts the belt 200, a positive voltage and a negative voltage are applied to the electrode pattern 400 of the belt 200. Therefore, as described above, the electrostatic attraction between the belt 200 and the sheet S is performed. Works. Then, the uppermost sheet S1 is attracted to the belt 200 in a state where the belt 200 is in surface contact with the uppermost sheet S1 with a predetermined contact area Mn. When the uppermost sheet S1 is adsorbed to the belt 200, the control unit 70 stops the first and second drive motors 203 and 204.

  The separation operation shown in FIG. 6E is an operation for separating the uppermost sheet S1 adsorbed by the belt 200 from the lower sheet S2 while elastically deforming it upward. In this separation operation, the control unit 70 causes the first drive motor 203 to rotate the first pinching and conveying roller pair 201 in the direction of the arrow in the drawing at a rotational speed U1d. At the same time, the control unit 70 causes the second nipping / conveying roller pair 202 to stop, or the second driving / conveying roller pair 202 is rotated by the second drive motor 204 at a rotational speed U2d that is slower than the rotational speed U1d. Let Thereby, the control unit 70 reduces the sag (deflection) and conveys the belt 200 in the direction of the arrow Au in the drawing. That is, by this separation operation, the belt 200 moves to a position (separation position) where the uppermost sheet S1 is separated from the lower sheet S2. This separation position is the distance Lb (bending length) from the leading edge of the sheet S1 to the bending root Pb, and the distance from the leading edge of the stacked sheets S1 to the leading edge when the sheet S1 is pulled up. It is a position to be deformed by the distance Lh (bending height).

  The conveyance operation shown in FIG. 6F is performed by conveying the belt 200 while maintaining the shape of the belt 200 after the separation operation, so that the uppermost sheet S1 adsorbed to the belt 200 is pulled out by the pair of drawing rollers 51d and 51e. It is an operation of conveying up to. In this conveyance operation, the control unit 70 causes the first and second drive motors 203 and 204 to rotate the first and second pinching and conveying roller pairs 201 and 202 at rotational speeds U1f and U2f in the arrow direction in the drawing, respectively. The control unit 70 makes the rotational speeds U1f and U2f substantially match. As a result, the belt 200 that has adsorbed the sheet S1 is conveyed while maintaining the shape of the adsorption surface side. As a result, the uppermost sheet S1 adsorbed to the belt 200 is conveyed in the direction of the arrow A in the figure while being adsorbed to the belt 200 while maintaining a state in which at least the front end is separated from the sheet S2 below.

  Thereafter, when the leading end of the uppermost sheet S1 comes close to the curved portion of the belt 200 formed by the first nipping / conveying inner roller 201a, the leading end of the uppermost sheet S1 peels off from the belt 200. The peeling occurs because the bending reaction force generated on the sheet S1 by the curved portion is larger than the electrostatic attraction force generated on the belt 200. In other words, the bending reaction force generated on the sheet S1 is set to be larger than the magnitude of the electrostatic attraction force generated on the belt 200. That is, by this conveyance operation, the belt 200 moves to a position (separation position) at which the uppermost sheet S1 is separated.

  Although the uppermost sheet S <b> 1 exfoliates from the front end after the front end exfoliates from the belt 200 as described above, the area on the rear end side is adsorbed by the belt 200. As a result, the sheet S1 is further conveyed by the belt 200 and is delivered to the drawing roller pair 51c, 51d.

  By the above six processes, only the uppermost sheet S1 is fed from the plurality of sheets S stacked in the cassette 51a. Then, by repeatedly performing the six steps, the sheets S can be continuously fed one by one.

6. Next, the principle of the charge removal on the surface of the belt 200 will be described. As a result of experiments by the present inventors, the following was found. That is, when the sheet S is removed from the belt 200 in a state where the belt 200 electrostatically attracts the sheet S (a state in which a voltage is applied to the electrode pattern 400), the voltage applied to the electrode pattern 400 by the surface of the belt 200 It is charged to the opposite polarity. When the surface of the belt 200 is thus charged, the belt 200 does not adsorb the next sheet S.

  FIG. 7 is a schematic view for explaining the principle of static elimination of the surface of the belt 200. As shown in FIG. FIG. 7A shows a state in which the sheet S is adsorbed to the belt 200, and a positive voltage and a negative voltage are applied to the first and second electrode portions 401 and 402, respectively. In FIG. 7B, the sheet S is peeled off from the belt 200 in a state in which the belt 200 electrostatically attracts the sheet S (a state in which a voltage is applied to the first and second electrode portions 401 and 402). It is a state. When the sheet S is peeled off from the belt 200 in this manner, as shown in FIG. 7C, the surfaces corresponding to the suction portions 411 and 421 of the first and second electrode portions 401 and 402 of the belt 200 are the first, It is charged in the opposite polarity to the voltage applied to each of the second electrode portions 401 and 402. This was found by an experiment of measuring the surface of the belt 200 with a surface voltmeter. In this state, as shown in FIG. 7D, even if it is attempted to cause the belt 200 to adsorb the next sheet S, the belt 200 does not adsorb the sheet S or the adsorption force of the belt 200 against the sheet S is weakened. I will. It is considered that this is because the voltages applied to the first and second electrode portions 401 and 402 and the charge on the surface of the belt 200 have opposite polarities, and these are offset to weaken the electrostatic force.

  Therefore, as shown in FIG. 7E, the application of the voltage to the electrode pattern 400 is stopped, the electrode pattern 400 is set to the GND potential, and the surface of the belt 200 is discharged by the discharging brush 303 of the GND potential. Removing at least a portion of the surface charge; Thus, when the charge on the surface of the belt 200 is removed, as shown in FIG. 7F, the belt 200 can adsorb the sheet S again by electrostatic force. Here, as shown in FIG. 7G, even when the surface of the belt 200 is removed by the discharging brush 303 while the voltage is applied to the electrode pattern 400, the charge on the surface of the belt 200 is sufficiently removed. Can not. These things were understood by the experiment which measures the surface of belt 200 with a surface voltmeter.

7. Next, a feeding operation including the charge removal on the surface of the belt 200 in the case of using the belt 200 having the “collective power feeding pattern” shown in FIG. 3 will be described. FIGS. 8 (a) to 8 (c) are schematic diagrams showing, in time series, how the sheet S is adsorbed, separated, and transported using the belt 200 shown in FIG.

  In the belt 200 shown in FIG. 3, when a voltage is applied to the feeding portions 412 and 422 of the electrode pattern 400, the voltage is applied collectively to the attraction portions 411 and 421 of the electrode pattern 400 around the entire circumference of the belt 200. . Therefore, the changeover switch 220 is provided between the first and second power supplies 205a and 205b and the first and second contacts 206a and 206b. The switch 220 can switch whether to apply a voltage to the electrode pattern 400 or to connect the electrode pattern 400 to the GND potential.

  In the state shown in FIGS. 8A and 8B, a voltage is applied across the entire circumference of the belt 200 from the first and second feed rollers 501 and 502 at both ends of the second pinching and conveying inner roller 202a. The electrostatic force is generated over the entire circumference of the belt 200. Therefore, in the state shown in FIG. 8A, the belt 200 adsorbs the sheet S and separates and feeds it. Further, in the state shown in FIG. 8B, the belt 200 conveys the attracted sheet S. At this time, in a state where a voltage is applied to the belt 200, the sheet S is peeled off from the belt 200 by the force due to the curvature separation, so the surface of the belt 200 is charged as described above.

  Therefore, as shown in FIG. 8C, the changeover switch 220 switches the potential applied to the first and second power supply rollers 501 and 502 to the GND potential. As a result, the surface of the belt 200 is discharged by the discharging brush 303 with the potential of the electrode pattern 400 as the GND potential over the entire circumference of the belt 200. Such switching of the potential of the electrode pattern 400 to the GND potential can not be performed during conveyance shown in FIG. 8B because electrostatic force is lost and the sheet S is dropped, and needs to be performed after the conveyance is completed. is there. Therefore, after the conveyance of one sheet S is completed, it is necessary to switch the potential of the electrode pattern 400 to the GND potential, and to rotate the belt 200 once in order to discharge the surface of the belt 200. Then, after one rotation for the charge removal is completed, it is necessary to switch the changeover switch 220 to the side of the first and second power supplies 205a and 205b to return to a series of feeding operations.

  As described above, when using the belt 200 having the “collective power feeding pattern” shown in FIG. 3, one rotation of the belt 200 is performed in order to discharge the surface of the belt 200 every time one sheet S is separated and fed. It is necessary to add an operation to carry. Therefore, when the belt 200 shown in FIG. 3 is used, the throughput (the number of fed sheets per unit time) is lowered.

8. Belt of Partial Feeding Pattern FIG. 9 is a schematic view showing an ideal feeding state to the electrode pattern 400 of the belt 200 in the sheet feeding device 51 using the slack of the belt 200. As shown in FIG.

  As described above, in the sheet feeding device 51 using the slack of the belt 200, the portion sandwiched by the first nipping and conveying roller pair 201 and the second nipping and conveying roller pair 202 most stably contacts the belt 200. And stable electrical connection can be obtained. Therefore, in the present embodiment, electrical connection is made to the electrode pattern 400 of the belt 200 from the feed members provided at both ends of each of the first and second pinching and conveying inner rollers 201a and 202a.

  That is, as described with reference to FIG. 4, in the present embodiment, the first feed roller 501 as a first feed member is provided at both ends of the second pinching and conveying inner roller 202 a in the rotational axis direction, A second feed roller 502 as a second feed member is provided (see FIG. 11). The first power feeding roller 501 and the second power feeding roller 502 respectively contact the power feeding portions 412 and 422 of the electrode pattern 400 exposed on the inner peripheral surface of the belt 200. Further, the first contact point 206a and the second contact point 206b described above are in contact with the first power feeding roller 501 and the second power feeding roller 502, respectively. As a result, the first and second power supplies 205a and 205b are electrically connected to the suction portions 411 and 421 of the electrode pattern 400. Further, in this embodiment, the first contact roller 503 as a first contact member and the second contact roller 504 as a second contact member are provided at both end portions of the first nipping and conveying inner roller 201a in the rotation axis direction. , Is provided (see FIG. 12). The first contact roller 503 and the second contact roller 504 respectively contact the feeding portions 412 and 422 of the electrode pattern 400 exposed on the inner peripheral surface of the belt 200. Further, the third contact point 207 a and the fourth contact point 207 b are in contact with the first contact roller 503 and the second contact roller 504, respectively. The third and fourth contacts 207a and 207b have the same configuration as the first and second contacts 206a and 206b, respectively, and are connected (electrically grounded) to the GND potential. Thus, the suction portions 411 and 421 of the electrode pattern 400 are electrically connected to the GND potential.

  In FIG. 9, the first and second contact rollers 503 and 504 at both ends of the first nipping and conveying inner roller 201a are connected to the GND potential. Further, the first and second power feeding rollers 501 and 502 at both ends of the second pinching and conveying inner roller 202a are connected to the first and second power supplies 205a and 205b, respectively. In this state, a voltage is applied to the electrode pattern 400 in the feeding ranges 231a and 231b shown in FIGS. 9A and 9B, and it is ideal that the electrode pattern 400 is connected to the GND potential in the discharging ranges 232a and 232b. It is. The feeding ranges 231a and 231b are predetermined ranges in contact with the uppermost sheet S between the contact portion with the second nipping inner roller 202a in the feeding direction of the belt 200 and the first nipping inner roller 201a. Further, the charge removal ranges 232a and 232b are predetermined ranges including a contact portion with the charge removal brush 303 from the first nipping / conveying inner roller 201a to the second nipping / conveying inner roller 202a in the conveyance direction of the belt 200. This is due to the following reasons. That is, in the state of FIG. 9A, the sheet S can be attracted to the belt 200 by applying a voltage to the electrode pattern 400 of the feeding range 231a including the contact area Mn. Further, in the state of FIG. 9B, the sheet S can be transported by applying a voltage to the electrode pattern 400 of the power supply range 231b. Then, in the state shown in FIGS. 9A and 9B, the electrode pattern 400 of the charge removal ranges 232a and 232b is connected to the GND potential, so that the surface of the belt 200 can be removed. With such an ideal power feeding state, the charge removal of the surface of the belt 200 is always performed in the charge removal ranges 232a and 232b in any of the suction, separation, and conveyance steps of the sheet S. There is no need to rotate the belt 200 once.

  FIG. 10 is a schematic view of a belt 200 of a “partial feed pattern” capable of realizing the above-described ideal feed state. FIG. 10 (a) is a developed view of the belt 200 as viewed from the inner peripheral surface side (the adsorbing portions 411 and 421 provided inside the belt 200 are also shown), and FIG. 10 (b) is FIG. 10 (c) is a cross-sectional view of a portion of the belt 200. FIG.

  The belt 200 of the "partial power feeding pattern" shown in FIG. 10 has a belt main body (base material) 200A and an electrode pattern 400 formed on the belt main body 200A, similarly to the belt 200 of the "collective power feeding pattern" shown in FIG. And. The electrode pattern 400 includes a first electrode portion 401 and a second electrode portion 402. The first electrode unit 401 includes a plurality of suction units 411 and a plurality of feed units 412. The plurality of suction portions 411 are spaced from each other in the circumferential direction of the belt 200, and are formed so as to extend substantially in parallel with the width direction of the belt 200. The plurality of power feeding units 412 are connected to the plurality of suction units 411 in the vicinity of the end in the width direction of the belt 200. Each feed portion 412 is formed to extend obliquely to the width direction of the belt 200 and to the upstream side in the conveyance direction of the belt 200. In the present embodiment, each power feeding portion 412 is formed to extend linearly from the end of the suction portion 411 toward the outside of the belt 200 in the width direction of the belt 200. Further, in the present embodiment, the respective feeding parts 412 are formed to extend substantially in parallel with each other. The length of each feeding portion 412 is set to a length that can achieve the above-described ideal feeding state. That is, the length of the feeding portion 412 is set such that the feeding portion 412 corresponding to the attracting portion 411 performs the first feeding before the attracting portion 411 which has passed the second pinching / conveying inner roller 202a reaches the first pinching / conveying inner roller 201a. The length away from the roller 501 is set. Similarly, the second electrode unit 402 includes a plurality of suction units 421 and a plurality of power supply units 422. The width direction of the belt 200 is a direction orthogonal to the conveyance direction of the belt 200 (moving direction of the surface). As described above, the suction portions 411 and 421 of the first and second electrode portions 401 and 402 have a comb-tooth shape, and the suction portion 411 of the first electrode portion 401 and the suction portion 421 of the second electrode portion 402 are They are alternately arranged in the circumferential direction of the belt 200. The plurality of feed portions 412 and 422 of the first and second electrode portions 401 and 402 have the belt 200 so that one feed portion 412 or 422 corresponds to one suction portion 411 or 421. It is disposed near the opposite end in the width direction.

  The adsorbing portions 411 and 421 are provided on the outer peripheral surface side of the cylindrical base layer 200 a. In addition, the feeding portions 412 and 422 are provided on the inner peripheral surface side of the cylindrical base layer 200a. Further, a through hole 403 penetrating the base layer 200a is provided in the base layer 200a. Then, a dielectric layer (adsorption layer) 200 b is applied on the outer peripheral surface of the base layer 200 a so as to cover the adsorption portions 411 and 421. Thus, the adsorbing portions 411 and 421 are disposed inside the belt main body 200A configured by the base layer 200a and the dielectric layer belt 200b. Further, the feeding portions 412 and 422 are exposed on the inner peripheral surface side of the belt main body 200A configured by the base layer 200a and the dielectric layer belt 200b. The feed portions 412 and 422 are electrically connected to the suction portions 411 and 421, respectively, by a conductive material (which may be the same material as the suction portion or the feed portion) through the through holes 403. In the belt 200, power is supplied to the electrode pattern 400 in the area corresponding to the feed parts 412 and 422 in the width direction, and electrostatic force is generated in the area corresponding to the suction parts 411 and 412 in the width direction to Adsorb.

  In the present embodiment, the base layer 200a is made of, for example, a film formed of an insulating resin such as PEN (polyethylene naphthalate). Further, in the present embodiment, the dielectric layer 200b is made of, for example, a resin of a dielectric such as polyimide. The first and second electrode portions 401 and 402 are made of, for example, metal (for example, copper).

  FIG. 11 is a schematic view showing how a voltage is applied to the electrode pattern 400 of the belt 200 shown in FIG. FIG. 11A is a schematic perspective view of the second pinching and conveying inner roller 202a. FIG. 11 (b) shows a state in which the electrode pattern 400 is fed, the developed view of the belt 200 shown in FIG. 10 as viewed from the inner peripheral surface side (the adsorption portions 411 and 421 provided inside the belt 200 are also shown) It is). A positive voltage is supplied from the first power feeding roller 501 provided at one end of the second nipping / conveying inner roller 202 a to the suction portion 411 of the first electrode portion 401 via the power feeding portion 412. Further, a negative voltage is supplied from the second power feeding roller 502 provided at the other end of the second nipping / conveying inner roller 202 a to the suction portion 421 of the second electrode portion 402 via the power feeding portion 422. That is, the feeding portions 412 and 422 are exposed on the inner peripheral surface side of the belt 200. Then, a voltage is applied to the feeding portions 412 and 422 in contact with the first and second feeding rollers 501 and 502 at both ends of the second nipping and conveying inner roller 202a. On the other hand, the feed portions 412 and 422 not in contact with the first and second feed rollers 501 and 502 are not electrically connected. As a result, voltage is supplied to the adsorbing portions 411 and 421 of the power supply range 250 in the conveyance direction of the belt 200, and the belt 200 of the corresponding portion can generate electrostatic force. On the other hand, the adsorbing portions 411 and 421 other than the power supply range 250 in the transport direction of the belt 200 can be electrically disconnected.

  FIG. 12 is a schematic view showing how the electrode pattern 400 of the belt 200 shown in FIG. 10 is connected to the GND potential. FIG. 12A is a schematic perspective view of the first nipping and conveying inner roller 201a. FIG. 12B is a developed view of the belt 200 shown in FIG. 10 viewed from the inner peripheral surface side (a suction portion 411, 421 provided inside the belt 200) showing how the electrode pattern 400 is connected to the GND potential. Is also shown). As in the case of voltage application shown in FIG. 11, the adsorption portions 411 and 421 of the charge removal range 251 in the transport direction of the belt 200 are connected to the GND potential, and the surface of the belt 200 of the corresponding portion can be removed. Become. On the other hand, the adsorbing portions 411 and 421 other than the charge removal range 251 in the conveyance direction of the belt 200 can be electrically disconnected.

  Thus, by using the belt 200 of the "partial power feeding pattern" shown in FIG. 10, it is possible to achieve the ideal power feeding state as shown in FIG. Therefore, it is not necessary to rotate the belt 200 once for the charge removal, so that it is possible to suppress the decrease in throughput.

9. Manufacturing Method Next, a method of manufacturing the belt 200 will be described.

  First, a method of manufacturing the belt 200 having the “collective power feeding pattern” shown in FIG. 3 will be described. As shown in FIG. 13A, an electrode pattern 400 is formed on a flat sheet-like (in this example, substantially rectangular) base layer 200a. And as shown in FIG.13 (b), the bonding parts 200h and 200i of the both ends of the base layer 200a are bonded together by ultrasonic welding, and it is made cylindrical shape. Thereafter, the dielectric layer 200b is applied on the outer peripheral surface of the cylindrical sheet. The belt 200 can be manufactured relatively easily and inexpensively by a known method by these series of processes.

  Next, a method of manufacturing the belt 200 of the “partial power feeding pattern” shown in FIG. 10 will be described. The belt 200 is a method of forming an electrode pattern on a flat sheet-like base layer 200a, and bonding opposing ends of the base layer 200a to form a cylindrical shape (herein also referred to as "bonding method"). It is very difficult to manufacture. This is due to the following reasons. That is, as shown in FIG. 14A, the electrode pattern 400 is formed on a flat sheet-like (in this example, substantially rectangular) base layer 200a. And as shown in FIG.14 (b), the bonding parts 200h and 200i of the both ends of the base layer 200a are bonded together by ultrasonic welding, and it is made cylindrical shape. Then, the feeding parts 412 and 422 become discontinuous. Therefore, in order to form the feeding parts 412 and 422 continuously, a special and relatively expensive manufacturing method in which an electrode pattern is formed on the inner peripheral surface side and the outer peripheral surface side of the insulating base layer made cylindrical in advance. Is considered necessary.

10. As described above, in order to achieve the ideal feeding state as shown in FIG. 9, it is desirable to use the belt 200 of “collective feeding pattern” as shown in FIG. As described above, it is very difficult to manufacture this belt 200 by the "bonding method". However, as shown in FIG. 15, this belt 200 also uses the bonding part 270 when the gap 281 between the suction parts 411 and 421 of the electrode pattern 400 and the gap 282 between the feed parts 412 and 422 are sufficiently wide. It is possible to manufacture by the "pasting method". However, according to the study of the present inventors, the space 281 between the suction parts 411 and 421 is 0.5 mm as an example, and the space 282 between the power supply parts 412 and 422 is 0.3 mm as an example. Therefore, it is very difficult to manufacture this belt 200 by the “bonding and manufacturing method”. Further, the inter-adhering part bonding part 271 which is a bonding part (glue margin) 270 between the suction parts 411 and 421 has the same conditions as the belt 200 of the “collective power feeding pattern” shown in FIG. 3. However, more accurate positioning is required because the inter-feed portion bonding portion 272 which is a bonding portion (glue margin) 270 between the power feeding portions 412 and 422 is narrower than the belt 200 of the “collective power feeding pattern” shown in FIG. Be done.

  Therefore, in the present embodiment, a part of the electrode pattern 400 of the belt 200 of the "partial power feeding pattern" is changed to widen the bonding portion 270 (particularly, the feeding portion bonding portion 272), which facilitates welding. Secure enough space for

  16 (a) to 16 (c) are plan views of a portion of the belt 200 in the present embodiment as viewed from the inner peripheral surface side (the inside of the belt 200) for explaining a modification of the portion of the electrode pattern 400. The adsorption | suction part 411,421 provided in these is also shown. Here, description will be given focusing on the upper end in the case where the upstream side in the transport direction of the belt 200 is the left side and the downstream side is the right side. The terms “upstream and downstream” with respect to the belt 200 refer to the upstream and downstream in the transport direction of the belt 200, and the indication that the transport direction of the belt 200 is appropriately omitted. Here, the suction unit 411 and the feed unit 412 of the first electrode unit 401 closest to the upstream side of the bonding unit 270 and the suction unit of the second electrode unit 402 closest to the downstream side of the bonding unit 270 It is assumed that ultrasonic welding is performed between 421 and the feeding portion 422. Each example shown in FIGS. 16 (a) to 16 (c) will be described below. In any of the examples, the change is the change of the power feeding portion 412 of the first electrode portion 401 closest to the upstream side of the bonding portion 270.

  First, an example shown in FIG. 16 (a) will be described. As shown in FIG. 16A, in the present embodiment, in the belt 200, the feed roller 501 and the feed portion 412 are brought into contact with each other in the width direction of the belt 200 to feed the feed portion 412. As a region, it has a first feeding region 291 and a second feeding region 292. The first power feeding region 291 is disposed at the end of the belt 200 in the width direction. The second feed region 292 is disposed adjacent to the first feed region 291 in the width direction of the belt 200. The first and second feed regions 291 and 292 are also regions where contact between the contact roller 503 and the feed portion 412 in the width direction of the belt 200 is performed and connection of the feed portion 412 to the GND potential is performed. is there. The first feeding region 291 is a region where feeding is performed to a feeding unit (first feeding unit) 412 whose arrangement is not changed as described later. Further, the second feeding region is a region where feeding is performed to the feeding unit (second feeding unit) 412 whose arrangement has been changed as described later.

  Then, in the belt 200 shown in FIG. 16A, the power feeding portion 412a of the first electrode portion 401 closest (closest to the upstream side) to the upstream side of the bonding portion 270 is separated from the bonding portion 270. It is arranged in the feeding region 292. The feeding portion 412 a is formed to extend linearly in parallel with the conveyance direction of the belt 200. The feed section 412 a and the suction section 411 a of the first electrode section 401 closest to the upstream side of the bonding section 270 are electrically connected via the through holes 403 as described above. The suction portions 411 and 421 extend in the width direction of the belt 200 to a region overlapping the second power feeding region 292.

  The feed portion 412 a disposed in the second feed region 292 has a three-dimensional intersection with the suction portions 411 and 421 on the front and back of the base layer 200 a (e.g., a portion denoted by reference numeral 290 in the drawing). Therefore, it is desirable that there is sufficient withstand voltage at the front and back of the base layer 200a. Here, for example, in the case of the PEN (polyethylene naphthalate) film used as the base layer 200a in the present embodiment, since the dielectric breakdown voltage is 200 kV / mm, for example, when the thickness of the base layer 200a is 75 μm, the dielectric withstand voltage is sufficient up to 15 kV. Is obtained. Therefore, in the experiments of the present inventors, in the range of several hundred to several kilovolts, which is a voltage required to be applied to the electrode pattern 400, the belt 200 is sufficiently used even if there is a crossover as described above. Is possible.

  Further, a length 285 of the feeding portion 412 disposed in the first feeding region 291 in the transport direction of the belt 200, and a length 286 in the transport direction of the belt 200 of the feeding portion 412a disposed in the second feeding region 292; Are preferably substantially the same. Thus, in order to achieve the feeding state as shown in FIG. 9, the functions of the feeding parts 412 and 412a respectively disposed in the first and second feeding regions 291 and 292 can be made equal.

  As described above, in the belt 200 shown in FIG. 16A, the bonding portion 270 (particularly, the feeding portion bonding portion 272) can be widely secured, and the bonding can be easily performed.

  In the example of FIG. 16A, the arrangement of the single power feeding unit 412 closest to the upstream side of the bonding unit 270 is changed. However, a plurality of power feeding units 412 close to the upstream side of the bonding unit 270 You may change the arrangement of For example, two power feedings of the feeding portion 412 of the first electrode portion 401 closest to the upstream side of the bonding portion 270 and the feeding portion 412 of the first electrode portion 401 adjacent to the upstream side of the feeding portion 412 The arrangement of the part 412 can be changed. In this case, the respective feeding portions 412 may be disposed at different positions in the width direction of the belt 200 (see FIG. 17C of the second embodiment).

  Next, an example shown in FIG. 16 (b) will be described. In the belt 200 shown in FIG. 16B, as in the belt 200 shown in FIG. 16A, the feeding portion 412a of the first electrode portion 401 closest to the upstream side of the bonding portion 270 has a second feeding region. Placed at 292. The feeding portion 412 a is formed to extend linearly in parallel with the conveyance direction of the belt 200. The feeding portion 412 a is adjacent to the suction portion 411 a of the first electrode portion 401 closest to the upstream side of the bonding portion 270 and the upstream side of the suction portion 411 a (opposite to the bonding portion 270). The suction portion 411 b of the first electrode portion 401 is electrically connected. The adsorption portion 411b is an adsorption portion 411 which is at the same potential as the adsorption portion 411a. The feed portion 412 a and the suction portions 411 a and 411 b are electrically connected to each other through the through holes 403 as described above. Thus, the adsorption portion 411a of the first electrode portion 401 closest to the upstream side of the bonding portion 270 has the same voltage as the adsorption portion 411b of the first electrode portion 401 adjacent to the upstream side of the adsorption portion 411a. Applied.

  The feed portion 412 a disposed in the second feed region 292 three-dimensionally intersects the suction portion 421 (the portion denoted by reference numeral 290 in the drawing). However, as with the belt 200 shown in FIG. 16A, the withstand voltage of the base layer 200a has a sufficient margin. Further, in the belt 200 of FIG. 16B, the bonding portion 270 can be secured wider than the belt 200 of FIG. 16A. However, in the belt 200 shown in FIG. 16B, the feed ranges 231a and 231b shown in FIG. 9 are shifted by one pitch of the suction portions 411 of the same potential. The pitch is the distance between the centers of the suction portions 411 in the moving direction of the belt 200. Therefore, the power supply ranges 231a and 231b are changed by one pitch per one turn of the belt 200. However, according to the study of the present inventors, while the power supply ranges 231a and 231b are, for example, 60 mm, one pitch corresponds to 3 mm. Therefore, there is almost no problem in the performance of the separation and feeding of the sheet S.

  The feed portion 412a disposed in the second feed region 292 may be directly connected to the feed portion 412 disposed in the first feed region 291 connected to the adsorption portion 411b, for example, on the back surface of the base layer 200a. Good. In that case, the connection portion is at a position avoiding the bonding portion 270.

  Next, an example shown in FIG. 16C will be described. The belt 200 shown in FIG. 16C has the same configuration as the belt 200 shown in FIG. 16B on the upstream side of the bonding section 270. Then, in the belt 200 of FIG. 16C, the feeding portion (third feeding portion) 412 c of the first electrode portion 401 closest to the downstream side of the bonding portion 270 is also disposed in the second feeding region 292. The feeding portion 412 c is formed to extend linearly in parallel with the conveyance direction of the belt 200. Then, the suction portion 411d of the first electrode portion 401 closest to the downstream side of the bonding portion 270 and the downstream side of the suction portion 411d (opposite to the bonding portion 270) are adjacent to each other by the power feeding portion 412c. The suction portion 411e of the first electrode portion 401 is electrically connected. The adsorption portion 411e is an adsorption portion 411 which is at the same potential as the adsorption portion 411d. The feed portion 412c and the suction portions 411d and 411e are electrically connected to each other through the through hole 403 as described above. Thus, the adsorption portion 411 d of the first electrode portion 401 closest to the downstream side of the bonding portion 270 has the same voltage as the adsorption portion 411 e of the first electrode portion 401 adjacent to the downstream side of the adsorption portion 411 d. Applied. As described above, the bonding portion 270 can be further widely secured by changing the power supply portion 412 of the first electrode portion 401 closest to the downstream side of the bonding portion 270.

  The feed portion 412 a disposed in the second feed region 292 on the downstream side of the bonding portion 270 is also connected to the feed portion 412 disposed in the first feed region 291 connected to the adsorption portion 411 e, for example, the base layer 200 a. Can be connected directly on the back of the In that case, the connection portion is at a position avoiding the bonding portion 270.

  In addition, the change of the electrode pattern 400 in the downstream of the bonding part 270 as shown in FIG.16 (c) is applicable also to the example of Fig.16 (a). Similarly, the present invention can be applied to the examples of FIGS. 17 (b) to 17 (d) of Example 2 and the examples of FIGS. 18 (b) to 18 (d) of Example 3 described later.

  Here, the description has been made focusing on the upper end of the belt 200 in the drawing, but for the other end side, the feeding portion 422 of the second electrode portion 402 closest to the upstream side of the bonding portion 270 is You can change in the same way. In addition, also on the other end side, as in the example of FIG. 16C, the power feeding portion 412 of the second electrode portion 401 closest to the downstream side of the bonding portion 270 may be changed. If desired, the change of the electrode pattern 400 as described above may be performed only on one end side in the width direction of the belt 200.

  As described above, in the present embodiment, the sheet feeding device 51 has a flexible endless shape that adsorbs and transports the sheet S by applying a voltage to the electrode pattern 400 and moving the electrode pattern 400 in the circumferential direction. Belt 200 of FIG. The belt 200 includes a base layer 200a, an electrode pattern 400 provided on the base layer 200a, and a bonding portion 270 in which opposing end portions of the base layer 200a are bonded to each other. The electrode pattern 400 has a plurality of suction portions 411, 421 formed on the outer peripheral surface of the base layer 200a so as to extend in the width direction orthogonal to the circumferential direction at intervals in the circumferential direction. In addition, the electrode patterns 400 are alternately disposed on the opposite end side in the width direction in the circumferential direction, and are connected to each of the plurality of adsorption portions on the disposed end side, the electrode layer 400 It has a plurality of feed parts 412, 422 formed on the inner circumferential surface. The feeding parts 412 and 422 are formed to extend on the upstream side in the moving direction with respect to the suction parts 411 and 421 to which the feeding parts are connected. Further, in at least one end side in the width direction, a region where power feeding to the power feeding portion 412 is performed is the first power feeding region 291 at the end of the width direction and the width wider than the first power feeding region 291. And a second feed region 292 inside the direction. The plurality of power feeding units 412 includes a plurality of first power feeding units 412 disposed in the first power feeding region 291 on the at least one end side. Further, at the end portion side, at least one of the plurality of power feeding units 412 is disposed in the second power feeding region 292 including one closest to the bonding unit 270 which is close to the upstream side in the moving direction of the bonding unit 270. Have a second power feeding portion 412a. In the present embodiment, the first power feeding portion 412 is formed obliquely with respect to the width direction so as to be disposed on the outer side in the width direction as going to the upstream side in the movement direction. At both end sides in the width direction, a region where power feeding to the power feeding portion is performed includes the first power feeding region and the second power feeding region, and the plurality of power feeding portions are the first power feeding portion and the second power feeding region. And a power supply unit. Here, the length of the feeding portion 412 is longer than the pitch in the moving direction of the suction portion 411 connected to the feeding portion 412 on the same end side in the width direction. Further, in the present embodiment, the pitch in the moving direction of the suction portion 411 is substantially the same over the entire circumference of the belt 200.

  As described above, by changing a part of the electrode pattern 400, it is possible to widen the bonded portion 270 (in particular, the inter-feeder bonded portion 272). Thereby, welding can be facilitated by giving a margin to the bonding accuracy. Therefore, it is possible to manufacture the belt 200 achieving the ideal feeding state as shown in FIG. 9 by the relatively easy and inexpensive “bonding method”.

Example 2
Next, another embodiment of the present invention will be described. The basic configuration and operation of the image forming apparatus of the present embodiment are the same as the image forming apparatus of the first embodiment. Therefore, in the image forming apparatus of the present embodiment, elements having the same or corresponding functions or configurations as those of the image forming apparatus of the first embodiment are designated by the same reference numerals as in the first embodiment, and the detailed description is omitted. Do. As in the first embodiment, the belt 200 will be described focusing on the upper end when the upstream side in the transport direction of the belt 200 is on the left side and the downstream side is on the right side.

  FIG. 17A is a plan view of a portion of the belt 200 in the present embodiment as viewed from the inner peripheral surface side (the adsorption portions 411 and 421 provided inside the belt 200 are also shown). In the present embodiment, the suction portion 411 is formed closer to the end of the belt 200 in the width direction than in the first embodiment. Further, as in the first embodiment, in the present embodiment, each of the power feeding portions 412 is formed to extend obliquely to the upstream side with respect to the width direction of the belt 200. However, in the present embodiment, each power feeding portion 412 is formed to extend linearly from the end of the suction portion 411 toward the inside of the belt 200 in the width direction of the belt 200. Further, in the present embodiment, the respective feeding parts 412 are formed to extend substantially in parallel with each other. The feed unit 412 is electrically connected to the suction unit 411 via the through hole 403 at the end of the suction unit 411 as in the first embodiment. Although the adsorbing portion 411 and the feeding portion 412 three-dimensionally intersect on the front and back of the base layer 200a, as described in the first embodiment, the withstand voltage of the base layer 200a has a sufficient margin. In the case of such an electrode arrangement, it is impossible to manufacture the belt 200 by the “bonding method” regardless of the size of the pitch of the suction part 411 and the feed part 412.

  Therefore, in the present embodiment, by partially changing the electrode pattern 400, it is possible to manufacture the belt 200 by the “bonding method”. 17 (b) to 17 (d) are plan views of a portion of the belt 200 in this embodiment as viewed from the inner peripheral surface side (the inside of the belt 200) for explaining a modification of the portion of the electrode pattern 400. The adsorption | suction part 411,421 provided in these is also shown. Hereinafter, each example shown to FIG.17 (b)-(d) is demonstrated. In any of the examples, the feeding unit 412 of the first electrode unit 401 closest to the upstream side of the bonding unit 270 and the feeding unit 412 of the first electrode unit 401 adjacent to the upstream side thereof are changed.

  First, an example shown in FIG. 17B will be described. As shown in FIG. 17B, as in the first embodiment, in the present embodiment, the belt 200 has a first power feeding area 291 and a second power feeding area 292. The first power feeding region 291 is disposed at the end of the belt 200 in the width direction. The second feed region 292 is disposed adjacent to the first feed region 291 in the width direction of the belt 200. The first feeding region 291 is a region where feeding is performed to a feeding unit (first feeding unit) 412 whose arrangement is not changed as described later. Further, the second feeding region is a region where feeding is performed to the feeding unit (second feeding unit) 412 whose arrangement has been changed as described later.

  Then, in the belt 200 shown in FIG. 17B, the length in the width direction of the suction portions 411a, 421a and 411b close to the upstream side of the bonding portion 270 is shortened. Thus, the end portions of the suction portions 411 a, 421 a and 411 b are disposed on the inner side in the width direction of the belt 200 than the first power feeding region 291 so that the end portions do not overlap the first power feeding region 291. The suction unit 411 a is the suction unit 411 of the first electrode unit 401 closest to the upstream side of the bonding unit 270. Further, the adsorption portion 411b is an adsorption portion of the first electrode portion 401 adjacent to the upstream side (the opposite side to the bonding portion 270) of the adsorption portion 411a (that is, the same electric potential as the adsorption portion 411a). 411. Further, the adsorption portion 421a is an adsorption portion 421 of the second electrode portion 402 between the adsorption portions 411a and 411b. Further, in the belt 200 shown in FIG. 17B, the feeding portions 412a and 412b connected to the suction portions 411a and 411b of the shortened first electrode 401 are disposed in the second feeding region 292. That is, these feeding parts 412 a and 412 b are moved in parallel to the second feeding area 292 while maintaining the connection with the suction parts 411 a and 411 b.

  As a result, in the belt 200 shown in FIG. 17B, the bonding portion 270 can be secured, and the bonding portion 270 can bond. Further, since the electrode arrangement of the belt 200 shown in FIG. 17B corresponds to the arrangement in which the feeding parts 412a and 412b are merely moved in parallel to the second feeding area 292, the belt 200 of the feeding parts 412a and 412b is The length in the transport direction does not change. That is, the lengths of the feeding portions 412a and 412b disposed in the second feeding region 292 in the conveyance direction of the belt 200 and the lengths of the feeding portion 412 disposed in the first feeding region 291 in the conveyance direction of the belt 200 are approximately equal. It is the same. Therefore, there is no change in the function of the feeding parts 412a and 412b disposed in the second feeding region 292 in order to achieve the feeding state as shown in FIG.

  In the belt 200 shown in FIG. 17B, since a part (three in this example) of the suction parts 411 and 421 is short, the suction force to the sheet S of the corresponding belt 200 is smaller than the other parts. Can be That is, there may be a portion where the attraction force is smaller than the other portions, one for each rotation of the belt 200. However, there is no problem if the lengths of the suction portions 411 and 421 are secured so that the sheet S can be sufficiently suctioned even if the suction portions 411 and 421 are short.

  Next, an example shown in FIG. 17C will be described. The belt 200 shown in FIG. 17C is obtained by changing the electrode pattern 400 substantially the same as the belt 200 shown in FIG. 17B. However, in the belt 200 shown in FIG. 17C, the feeding parts 412a and 412b of the first electrode part 401 disposed in the second feeding area 292 extend linearly in a direction substantially parallel to the conveyance direction of the belt 200. It is formed. The feed portions 412a and 412b disposed in the second feed region 292 are disposed at different positions in the width direction of the belt 200 (in this example, the feed portion 412b is inside the width direction of the belt 200 than the feed portion 412a). Be done. Further, the lengths of the feeding portions 412a and 412b disposed in the second feeding region 292 in the conveyance direction of the belt 200 are substantially the same as the lengths of the feeding portion 412 disposed in the first feeding region 291 in the conveyance direction. It is assumed. Thereby, there is no change in the function of the feeding parts 412a and 412b disposed in the second feeding region 292 in order to achieve the feeding state as shown in FIG.

  Next, an example shown in FIG. 17D will be described. In the belt shown in FIG. 17D, as in the belt 200 shown in FIG. 17B, the length in the width direction of the belt 200 of the suction portions 411a, 421a, 411b close to the upstream side of the bonding portion 270 shorten. Then, a feeding portion 412 d for feeding the suction portions 411 a and 411 b of the shortened first electrode portion 401 is disposed in the second feeding region 292. The feeding portion 412 d is formed to extend linearly in parallel with the conveyance direction of the belt 200. The feeding portions 412e electrically connect the suction portions 411a and 411b of the shortened first electrode portion 401 and the suction portion 411c of the first electrode portion 401 adjacent to the further upstream side. Thus, a voltage is applied to the suction portions 411a and 411b of the shortened first electrode portion 401 at the same timing as the suction portion 411c of the first electrode portion 401 further upstream. In the belt 200 shown in FIG. 17 (d), although the power supply ranges 231a and 231b shown in FIG. 9 change one point for each rotation of the belt 200, the sheet S is the same as described in the first embodiment. There is almost no problem in the performance of the separate feeding of The feed portion 412d disposed in the second feed region 292 may be directly connected to the feed portion 412 disposed in the first feed region 291 connected to the adsorption portion 411c, for example, on the back surface of the base layer 200a. Good. In that case, the connection portion is at a position avoiding the bonding portion 270.

  Here, the description has been made focusing on the end of the belt 200 at the upper side in the drawing, but for the other end side, the suction portion 421 of the second electrode portion 402 close to the upstream side of the bonding portion 270 and the feeding portion 422 May be changed in the same manner as described above. If desired, the change of the electrode pattern 400 as described above may be performed only on one end side in the width direction of the belt 200.

  As described above, in the present embodiment, the first power feeding portion is formed obliquely with respect to the width direction so as to be disposed on the inner side in the width direction of the belt 200 as going to the upstream side in the moving direction of the belt 200 There is. And, in the present embodiment, on the at least one end side of the belt 200, the end in the width direction of the suction unit connected to the second power supply unit is the above-mentioned suction unit connected to the first power supply unit. It is arrange | positioned inside the said width direction rather than the end part of the width direction. Furthermore, in the present embodiment, the end in the width direction of the suction unit disposed between the plurality of suction units connected to the second power supply unit is the width of the suction unit connected to the first power supply unit. It is arrange | positioned inside the said width direction rather than the end part of the direction.

  As described above, by changing a part of the electrode pattern 400, it becomes possible to secure the bonding portion 270, and using this bonding portion 270, the belt 200 is manufactured by the “bonding method”. Is possible.

[Example 3]
Next, another embodiment of the present invention will be described. The basic configuration and operation of the image forming apparatus of the present embodiment are the same as the image forming apparatus of the first embodiment. Therefore, in the image forming apparatus of the present embodiment, elements having the same or corresponding functions or configurations as those of the image forming apparatus of the first embodiment are designated by the same reference numerals as in the first embodiment, and the detailed description is omitted. Do. As in the first embodiment, the belt 200 will be described focusing on the upper end when the upstream side in the transport direction of the belt 200 is on the left side and the downstream side is on the right side.

  FIG. 18A is a plan view of a portion of the belt 200 in the present embodiment as viewed from the inner peripheral surface side (the suction portions 411 and 421 provided inside the belt 200 are also shown). In the present embodiment, as in the second embodiment, the suction unit 411 is formed closer to the end of the belt 200 in the width direction than the first embodiment. Further, as in the second embodiment, in the present embodiment, each of the power feeding portions 412 is formed to extend obliquely to the width direction of the belt 200 and to the upstream side in the conveyance direction of the belt 200. However, in the present embodiment, in the width direction of the belt 200, each power feeding portion 412 linearly extends from the position on the inner side of the belt 200 by a predetermined distance than the end of the suction portion 411 toward the outside of the belt 200. It is formed to extend to Further, in the present embodiment, the respective feeding parts 412 are formed to extend substantially in parallel with each other. The feed portion 412 is electrically connected to the suction portion 411 via the through hole 403 at a position inside the width direction of the belt 200 by a predetermined distance from the end of the suction portion 411 as in the first embodiment. There is. Although the adsorbing portion 411 and the feeding portion 412 three-dimensionally intersect on the front and back of the base layer 200a, as described in the first embodiment, the withstand voltage of the base layer 200a has a sufficient margin. In the case of such an electrode arrangement, it is impossible to manufacture the belt 200 by the “bonding method” regardless of the size of the pitch of the suction part 411 and the feed part 412.

  Therefore, in the present embodiment, by partially changing the electrode pattern 400, it is possible to manufacture the belt 200 by the “bonding method”. 18 (b) to 18 (d) are plan views of a portion of the belt 200 in the present embodiment as viewed from the inner peripheral surface side (the inside of the belt 200) for explaining a modification of the portion of the electrode pattern 400. The adsorption | suction part 411,421 provided in these is also shown. Hereinafter, each example shown in FIG.18 (b)-(d) is demonstrated. Modification of the electrode pattern 400 in FIGS. 18B, 18C and 18D is substantially the same as the modification of the electrode pattern 400 in FIGS. 17B, 17C and 17D of the second embodiment, respectively. .

  First, an example shown in FIG. 18B will be described. In the belt 200 shown in FIG. 18B, as in the belt 200 shown in FIG. 17B, the length in the width direction of the suction portions 411a, 421a, 411b adjacent to the upstream side of the bonding portion 270 is shortened. . Further, in the belt 200 shown in FIG. 18B, the feeding parts 412a and 412b connected to the suction parts 411a and 411b of the first electrode part 401 shortened as in the belt 200 shown in FIG. 17B. , Parallel to the second feeding region 292. However, in the belt 200 shown in FIG. 18B, unlike the belt 200 shown in FIG. 17B, the feeding portion 412c adjacent to the downstream side of the end portions of the suction portions 411a, 421a and 411b shortened is It inclines from the inside in the width direction of the belt 200 to the outside. Therefore, the end portions of the shortened suction portions 411a, 421a, and 411b are sequentially provided on the outer side in the width direction of the belt 200 so that the distance between the adjacent suction portions 411a, 421a, and 411b and the feed portion 412c adjacent to the downstream side becomes substantially the same. Be placed. Therefore, in the belt 200 shown in FIG. 18B, the decrease in the attraction force of the belt 200 to the sheet S in the portion where the suction portions 411 and 412 are shortened is suppressed more than in the belt 200 shown in FIG. Can.

  Next, an example shown in FIG. 18C will be described. A belt 200 shown in FIG. 18C is obtained by changing the same electrode pattern 400 as the belt 200 shown in FIG. 17C to the belt 200 shown in FIG. However, in the belt 200 of FIG. 18C, as in FIG. 18B, the end portions of the shortened suction portions 411a, 421a, 411b are between the feed portion 412c adjacent to the downstream side thereof. The belts 200 are sequentially arranged on the outer side in the width direction of the belt 200 so that the distances become substantially the same. Therefore, in the belt 200 shown in FIG. 18C, the decrease in the attraction force of the belt 200 to the sheet S in the portion where the suction portions 411 and 412 are shortened is suppressed more than in the belt 200 shown in FIG. Can.

  Next, an example shown in FIG. 18D will be described. A belt 200 shown in FIG. 18D is obtained by changing the electrode pattern 400 similar to the belt 200 shown in FIG. 17D to the belt 200 shown in FIG. 18B. However, in the belt 200 of FIG. 18 (d), as in FIG. 18 (b), the end portions of the shortened suction portions 411a, 421a, 411b are between the feed portion 412c adjacent to the downstream side thereof. The belts 200 are sequentially arranged on the outer side in the width direction of the belt 200 so that the distances become substantially the same. Therefore, in the belt 200 shown in FIG. 18 (d), the decrease in the attraction force of the belt 200 to the sheet S in the portion where the suction portions 411 and 412 are shortened is suppressed more than the belt 200 shown in FIG. Can.

  Here, the description has been made focusing on the end of the belt 200 at the upper side in the drawing, but for the other end side, the suction portion 421 of the second electrode portion 402 close to the upstream side of the bonding portion 270 and the feeding portion 422 May be changed in the same manner as described above. If desired, the change of the electrode pattern 400 as described above may be performed only on one end side in the width direction of the belt 200.

  As described above, in the present embodiment, the first power feeding portion is next to the first position in the width direction of the belt 200 than the end in the width direction of the belt 200 of the suction portion connected to the first power feeding portion. It is formed like. That is, they are formed obliquely with respect to the width direction so as to be disposed on the outer side in the width direction as going to the upstream side in the moving direction of the belt 200.

  As described above, according to the present embodiment, as in the second embodiment, the bonded portion 270 can be secured, and the belt 200 is manufactured by the “bonding method” using the bonded portion 270. It is possible to Further, in the present embodiment, it is possible to suppress a decrease in the attraction force of the belt 200 to the sheet S caused by shortening the attraction parts 411 and 421 as compared with the second embodiment.

Reference Signs List 51 sheet feeding apparatus 100 image forming apparatus 200 electrostatic attraction belt 400 electrode pattern 401 first electrode part 402 second electrode part 411, 421 adsorption part 421, 422 feeding part

Claims (14)

A base layer, an electrode pattern provided on the base layer, and a bonding part in which opposing ends of the base layer are bonded to each other, a voltage is applied to the electrode pattern, and the electrode pattern is moved in the circumferential direction A flexible endless electrostatic adsorption belt for adsorbing and conveying a sheet,
The electrode pattern has a plurality of suction portions formed on the outer peripheral surface of the base layer so as to extend in the width direction orthogonal to the circumferential direction at intervals in the circumferential direction, and the width direction alternately in the circumferential direction And a plurality of feed portions formed on the inner circumferential surface of the base layer so as to be disposed on the opposite end side of the base and connected to each of the plurality of adsorption portions on the disposed end side And
The feeding unit is formed to extend upstream in the moving direction with respect to the suction unit to which the feeding unit is connected.
In at least one end side of the width direction, a region where power feeding to the power feeding portion is performed is a first power feeding region on the most end side in the width direction, and an inner side in the width direction than the first power feeding region. A second feed region of
At the at least one end side, the plurality of feeding units are adjacent to the plurality of first feeding units disposed in the first feeding region, and the upstream side of the moving direction of the bonding unit. An electrostatic attraction belt comprising: at least one second power feeding portion disposed in the second power feeding region including one closest to a joint portion.   The first power feeding portion is formed obliquely with respect to the width direction so as to be disposed on the outer side in the width direction as going to the upstream side in the movement direction. Electrostatic adsorption belt.   The first power feeding portion is formed obliquely to the width direction so as to be disposed on the inner side in the width direction as going to the upstream side in the moving direction. Electrostatic adsorption belt.   The first power feeding section moves in the width direction from the position on the inner side in the width direction with respect to the end in the width direction of the suction section to which the first power feeding section is connected. The electrostatic attraction belt according to claim 1, wherein the electrostatic attraction belt is formed obliquely to the width direction so as to be disposed on the outside of the belt.   At the at least one end side, the end in the width direction of the suction unit connected to the second power supply unit is the end of the suction unit in the width direction connected to the first power supply unit The electrostatic attraction belt according to claim 3, wherein the electrostatic attraction belt is disposed on the inner side in the width direction than the portion.   At the at least one end side, the end in the width direction of the suction unit disposed between the plurality of suction units connected to the second power supply unit is connected to the first power supply unit 6. The electrostatic attraction belt according to claim 5, wherein the electrostatic attraction belt is disposed on the inner side in the width direction than the end in the width direction of the attraction part.   The second power feeding unit is disposed on the upstream side of the moving direction from the suction unit to which the second power feeding unit is connected, the suction unit connected to the first power feeding unit, or the second power feeding unit The first power feeding unit according to any one of claims 1 to 6, wherein the first power feeding unit is connected to the suction unit disposed on the upstream side in the moving direction with respect to the suction unit to which the second power supply unit is connected. The electrostatic adsorption belt described in.   At both end sides in the width direction, a region where power feeding to the power feeding portion is performed includes the first power feeding region and the second power feeding region, and the plurality of power feeding portions are the first power feeding portion and the second power feeding region. The electrostatic attraction belt according to any one of claims 1 to 7, further comprising: a power feeding unit.   In at least one end side of the width direction, the plurality of power feeding units are adjacent to the downstream side of the moving direction of the bonding unit, in the second power feeding region including one closest to the bonding unit. The first power supply having at least one third power feeding unit disposed, wherein the third power feeding unit is disposed downstream of the suction unit to which the third power feeding unit is connected, in the moving direction. Connected to the suction unit connected to the suction unit, or to the suction unit connected to the suction unit disposed downstream of the suction unit to which the third power supply unit is connected. The electrostatic attraction belt according to any one of claims 1 to 8, characterized in that:   The length of the feed section is longer than the pitch in the moving direction of the suction section connected to the feed section on the same end side in the width direction. The electrostatic adsorption belt as described in a term.   The electrostatic capacitance according to any one of claims 1 to 10, wherein a length of the first feeding portion in the movement direction and a length of the second feeding portion in the movement direction are substantially the same. Suction belt.   The electrostatic attraction belt according to any one of claims 1 to 11, wherein the pitch in the moving direction of the attraction part is substantially the same over the entire circumference of the electrostatic attraction belt. A loading means on which sheets are loaded;
A first rotating body disposed above the loading means;
A second rotating body provided downstream of the first rotating body in the sheet conveying direction;
A flexible endless electrostatic adsorption belt having an inner surface supported by the first rotating body and the second rotating body and adsorbing and transporting sheets stacked on the stacking means;
A power supply for applying a voltage to an electrode pattern provided on the electrostatic attraction belt;
Have
A sheet feeding apparatus for attracting and conveying a sheet by forming a slack of the electrostatic attraction belt between the first rotating body and the second rotating body.
The sheet feeding apparatus according to any one of claims 1 to 12, wherein the electrostatic attraction belt is an electrostatic attraction belt according to any one of claims 1 to 12.   An image forming apparatus comprising: an image forming unit for forming an image on a sheet; and a sheet feeding apparatus according to claim 13 for feeding the sheet to the image forming unit.