JP2014218372A - Sheet feeder and image formation apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sheet feeder that can feed a sheet through electrostatic attraction with simple constitution and low noise, and an image formation apparatus.SOLUTION: An attraction member 410 comprises a linear part and a curved part, and the attraction member after being moved to an attraction position where the curved part comes into contact with a sheet through rotations of a holding and carrying roller pair 501 is elevated toward a drawing-out roller pair 51d, 51e while slackening is eliminated by the linear part, so that the sheet attracted by the attraction member 410 is passed to the drawing-out roller pair 51d, 51e.

Description

  The present invention relates to a sheet feeding apparatus and an image forming apparatus, and more particularly, to a sheet feeding apparatus using electrostatic attraction force.

  Conventional image forming apparatuses such as copiers and printers are provided with a sheet feeding device for feeding sheets. As such a sheet feeding device, the uppermost sheet is removed from a cassette on which a bundle of sheets is stacked with a rubber roller. There is a friction feeding type that separates and feeds using a frictional force. In the sheet feeding device of this friction feeding type, the uppermost sheet is fed out by rotating the rubber sheet while pressing the rubber roller against the sheet bundle. Here, when the sheets are sent out, a plurality of sheets are conveyed by friction between the sheets, so-called double feeding of the sheets may occur. In response to this, only the uppermost sheet is fed to the image forming unit by applying a conveyance resistance to the sheet other than the uppermost sheet by a separation pad or a retard roller.

  By the way, in such a sheet feeding device of the frictional separation system, since the sheet is fed while applying a large pressure to the sheet by the rubber roller, noise due to friction between the sheets and between the sheet and the rubber roller becomes a problem. Further, when the separation pad or the retard roller is used to prevent the sheets from being double-fed, a large rubbing noise is generated between the sheets. In addition, the separation pad and the retard roller provide resistance for transporting the uppermost sheet even when the sheet is not double-fed, so that a sound due to stick-slip between the separation pad or the retard roller and the sheet is generated. End up.

  Therefore, as a solution to this problem, there is a sheet feeding apparatus that uses an electrostatic attraction force, specifically, separates and feeds a sheet while adsorbing the sheet by an electric field formed on the belt surface (patent) Reference 1 and 2). In such an electrostatic adsorption separation type sheet feeding apparatus, the uppermost sheet can be conveyed so as to be peeled off from the sheet bundle, so that noise in the feeding portion can be greatly reduced. .

JP 2011-168396 A JP-A-5-139548

  However, in a sheet feeding apparatus that feeds a sheet using a conventional electrostatic attraction force, the configuration of Patent Document 1 can generate a sufficient electrostatic attraction force on the sheet. Occasionally, operating noise is generated because the frame carrying the suction belt is raised and lowered. Further, a collision sound with the seat is also generated. Furthermore, even when the sheet is curled, when the sheet is adsorbed, the sheet can be surely adsorbed, that is, the follow-up to the sheet curl when adsorbing the sheet of the adsorption belt can be secured. The belt distance is weakened by shortening the distance between the shafts. However, if the belt tension is weakened and the sheet is adsorbed, it is necessary to increase the tension during the separation operation. If the tension is increased in this way, string vibration occurs in the belt, and the vibration also causes sudden sound.

  In the configuration of Patent Document 2, the suction belt is used. However, the suction belt is not moved up and down with the frame, but the carrying roller is moved eccentrically, so that the sheet separation operation is performed. The sound is reduced. However, when the suction belt is surely brought into contact with the sheet bundle, a collision sound in which the roller collides with the sheet bundle via the suction belt is still generated. If an attempt is made to avoid the collision between the roller and the sheet bundle, the belt and the sheet bundle are separated from each other, and the suction of the sheet by the suction belt becomes unstable, resulting in poor feeding.

  Accordingly, the present invention has been made in view of such a current situation, and has a simple configuration, low noise, and a sheet feeding apparatus and an image that can stably perform sheet feeding by electrostatic attraction. An object of the present invention is to provide a forming apparatus.

  The present invention provides a stacking unit on which sheets are stacked, a first rotating body disposed above the stacking unit, an inner surface supported by the first rotating body, a first portion, and the first portion A first member that has a second part having a larger curvature than the part, and that electrically adsorbs the sheets stacked on the stacking unit, and a first holding member that holds the suction member together with the first rotating body And a first driving means for rotating the first rotating body and the first clamping member, and a control means for controlling the first driving means, wherein the control means comprises the second driving means. The sheet feeding device according to claim 1, wherein the sheet is transported upward by the first portion after adsorbing the sheet stacked on the stacking means by the portion.

  According to the present invention, the adsorbing member that electrically adsorbs the sheet has the first portion and the second portion having a larger curvature than the first portion, and is loaded on the loading means by the second portion. After adsorbing the sheet, the sheet is conveyed upward by the first portion. Therefore, it is possible to stably feed the sheet by electrostatic attraction with a simple configuration and low noise.

1 is a diagram illustrating a schematic configuration of an image forming apparatus including a sheet feeding device according to a first embodiment of the present invention. The figure explaining the structure of the said sheet feeding apparatus. The control block diagram of the said sheet feeding apparatus. The figure explaining the detailed principle of the adsorption member of the sheet | seat adsorption | suction separation feeding part provided in the said sheet | seat feeding apparatus, and the generation | occurrence | production principle of the adsorption | suction force in which an adsorption member adsorb | sucks a sheet | seat. The figure explaining the adsorption | suction member of the sheet | seat adsorption | suction separation feeding part provided in the said sheet | seat feeding apparatus. The figure explaining the sheet | seat separation feeding operation | movement of the said sheet | seat adsorption | suction separation feeding part. 4 is a timing chart at the time of sheet separation and feeding by the sheet suction separation and feeding unit. The figure explaining the structure of the sheet feeding apparatus which concerns on the 2nd Embodiment of this invention. The figure explaining the structure of the adsorption | suction member of the sheet | seat adsorption | suction separation feeding part provided in the said sheet | seat feeding apparatus. The figure explaining the sheet | seat separation feeding operation | movement of the said sheet | seat adsorption | suction separation feeding part. 4 is a timing chart at the time of sheet separation and feeding by the sheet suction separation and feeding unit. FIG. 6 is a diagram illustrating a configuration of a sheet feeding device according to a third embodiment of the present invention. The figure explaining the detailed principle of the adsorption member of the sheet | seat adsorption | suction separation feeding part provided in the said sheet | seat feeding apparatus, and the generation | occurrence | production principle of the adsorption | suction force in which an adsorption member adsorb | sucks a sheet | seat.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram illustrating a schematic configuration of an image forming apparatus including a sheet feeding device according to a first embodiment of the present invention.

  In FIG. 1, reference numeral 100 denotes an image forming apparatus, and 100A denotes an image forming apparatus main body (hereinafter referred to as an apparatus main body). An image reading unit 41 having an image sensor or the like that irradiates light on a document placed on a platen glass as a document placement table and converts reflected light into a digital signal is provided on the upper part of the apparatus main body 100A. A document for reading an image is conveyed onto the platen glass by the automatic document feeder 41a. Further, the apparatus main body 100A includes an image forming unit 55, sheet feeding devices 51 and 52 that feed the sheet S to the image forming unit 55, and a sheet reversing unit that reverses the sheet S and conveys it to the image forming unit 55. 59 is provided.

  The image forming unit 55 includes the exposure unit 42 and four process cartridges 43 (43y, 43m, 43) that form toner images of four colors of yellow (Y), magenta (M), cyan (C), and black (Bk). 43c, 43k). The image forming unit 55 includes an intermediate transfer unit 44, a secondary transfer unit 56, and a fixing unit 57 disposed above the process cartridge 43.

  Here, the process cartridge 43 includes the photosensitive drum 21 (21y, 21m, 21c, 21k), the charging roller 22 (22y, 22m, 22c, 22k), and the developing roller 23 (23y, 23m, 23c, 23k). I have. The process cartridge 43 includes a drum cleaning blade 24 (24y, 24m, 24c, 24k).

  The intermediate transfer unit 44 includes a belt driving roller 26, an intermediate transfer belt 25 stretched around the secondary transfer inner roller 56a, and the like, and a primary transfer roller that contacts the intermediate transfer belt 25 at a position facing the photosensitive drum 21. 27 (27y, 27m, 27c, 27k). Then, as will be described later, a positive transfer bias is applied to the intermediate transfer belt 25 by the primary transfer roller 27 so that toner images having a negative polarity on the photosensitive drum 21 are sequentially transferred to the intermediate transfer belt 25 in a multiple transfer manner. Is done. As a result, a full color image is formed on the intermediate transfer belt 25.

  The secondary transfer unit 56 includes a secondary transfer inner roller 56 a and a secondary transfer outer roller 56 b that is in contact with the secondary transfer inner roller 56 a via the intermediate transfer belt 25. Then, as described later, a full-color image formed on the intermediate transfer belt 25 is transferred to the sheet S by applying a positive secondary transfer bias to the secondary transfer outer roller 56b.

  The fixing unit 57 includes a fixing roller 57a and a fixing backup roller 57b. Then, the sheet S is nipped and conveyed between the fixing roller 57a and the fixing backup roller 57b, whereby the toner image on the sheet S is pressurized and heated to be fixed to the sheet S. The sheet feeding devices 51 and 52 include cassettes 51a and 52a that are storage units (stacking units) for storing the sheets S, respectively. In addition, the sheet feeding devices 51 and 52 include sheet suction separation feeding units 51b and 52b having a function of feeding the sheets S stored in the cassettes 51a and 52a one by one while being attracted by static electricity. .

  In FIG. 1, reference numeral 103 denotes a pre-secondary transfer conveyance path for conveying the sheet S fed from the cassettes 51 a and 52 a to the secondary transfer unit 56, and reference numeral 104 denotes two sheets S conveyed to the secondary transfer unit 56. This is a pre-fixing transport path for transporting from the next transfer unit 56 to the fixing unit 57. Reference numeral 105 denotes a post-fixing conveyance path for conveying the sheet S conveyed to the fixing unit 57 from the fixing unit 57 to the switching member 61, and reference numeral 106 denotes a sheet S conveyed to the switching member 61 from the switching member 61 to the paper discharge unit 58. This is a paper discharge path. Reference numeral 107 denotes a re-conveying path for conveying the sheet S reversed by the sheet reversing unit 59 to the image forming unit 55 in order to form an image on the back surface of the sheet S on which an image is formed on one side by the image forming unit 55.

  Next, an image forming operation of the image forming apparatus 100 having such a configuration will be described. When the image forming operation is started, first, the exposure unit 42 irradiates the surface of the photosensitive drum 21 with laser light based on image information from a personal computer (not shown). At this time, the surface of the photosensitive drum 21 is uniformly charged to a predetermined polarity / potential by the charging roller 22, and when the laser beam is irradiated, the charge of the portion irradiated with the laser beam is attenuated, thereby exposing the photosensitive drum 21. An electrostatic latent image is formed on the surface of the body drum.

  Thereafter, the electrostatic latent image is developed with yellow (Y), magenta (M), cyan (C), and black (Bk) toners respectively supplied from the developing roller 23, and the electrostatic latent image is developed as a toner image. Image. Each color toner image is sequentially transferred to the intermediate transfer belt 25 by the primary transfer bias applied to the primary transfer roller 27, whereby a full color toner image is formed on the intermediate transfer belt 25.

  On the other hand, in parallel with the toner image forming operation, the sheet feeding devices 51 and 52 separate and feed only one sheet S from the cassettes 51a and 52a by the sheet suction separation feeding units 51b and 52b. Thereafter, the sheet S is detected by the sheet leading edge detection sensors 51c and 52c, and reaches the drawing roller pair 51d and 51e. Further, the sheet S sandwiched between the drawing roller pairs 51d and 51e is sent to the pre-secondary transfer conveyance path 103, and the position of the leading edge is adjusted by contacting the stopped registration roller pair 62a and 62b.

  Next, in the secondary transfer unit 56, the registration roller pairs 62a and 62b are driven at a timing at which the full-color toner image on the intermediate transfer belt and the position of the sheet S coincide with each other. As a result, the sheet S is conveyed to the secondary transfer unit 56, and the full-color toner image is transferred onto the sheet S by the secondary transfer unit 56 by the secondary transfer bias applied to the secondary transfer outer roller 56b. Is done.

  The sheet S on which the full-color toner image has been transferred is conveyed to the fixing unit 57 where the toner of each color is melted and mixed by receiving heat and pressure, and is fixed on the sheet S as a full-color image. Thereafter, the sheet S on which the image is fixed is discharged by a paper discharge unit 58 provided downstream of the fixing unit 57. When forming images on both sides of the sheet, the conveyance 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.

  Next, the configuration of the sheet feeding apparatus 51 according to the present embodiment will be described with reference to FIG. As described above, the sheet feeding device 51 includes the cassette 51a and the sheet suction separation feeding unit 51b that feeds the sheets S stored in the cassette 51a one by one while being electrically attracted by static electricity. ing. The sheet feeding device 51 is provided so as to be movable up and down in the cassette 51a. The sheet feeding device 51 lifts and lowers the middle plate 301a on which the sheet S is stacked, and the sheet S fed by the sheet suction separation feeding unit 51b. A sheet leading edge detection sensor 51c that detects passage is provided.

  The sheet adsorbing and separating unit 51b includes a pair of nipping and conveying rollers 501 that are nipping and conveying members including a nipping and conveying inner roller (first rotating body) 501a and a nipping and conveying outer roller (first nipping member) 501b. I have. In addition, a flexible endless suction member 410 sandwiched between the pair of sandwiching conveyance rollers 501, a first drive unit 203, and a power supply unit 205 are provided. The pair of nipping and conveying rollers 501 is disposed with a predetermined gap Lrgap from the upper surface of the uppermost sheet stacked on the cassette 51a. The inner surface of the suction member 410 is supported by the nipping and conveying inner roller 501a. In the present embodiment, the drawing roller pairs 51d and 51e are arranged above the nipping and conveying roller pair 501. Note that the sheet suction separation and feeding unit 52b provided in the sheet feeding device 52 has the same configuration as the sheet suction separation and feeding unit 51b of the sheet feeding device 51, and thus description thereof is omitted.

  The lifting / lowering means 301 includes a lifter 301b rotatably provided below the middle plate 301a, and the middle plate 301a and the uppermost sheet Sa stacked on the middle plate 301a according to the rotation angle of the lifter 301b. Change the position. The sheet leading edge detection sensor 51c is disposed in the sheet conveyance path between the sheet suction separation feeding unit 51b and the drawing roller pair 51d and 51e. The success or failure of sheet feeding is detected based on whether or not the sheet leading edge detection sensor 51c detects the sheet S at a predetermined timing. In the present embodiment, the sheet leading edge detection sensor 51c is a non-contact reflective photosensor, which irradiates a detection target with spot light and measures the amount of reflected light to detect the presence or absence of the detection target.

  In FIG. 2, reference numeral 302 denotes a paper surface height detecting means for detecting the upper surface position of the sheets S stacked on the intermediate plate 301a. The paper surface height detection means 302 is disposed above the intermediate plate 301a and is constituted by a sensor flag 302a and a photosensor 302b. The sensor flag 302a is rotatably supported by a support unit (not shown), and one end is disposed at a position where it can come into contact with the upper surface of the uppermost sheet Sa, and the other end is disposed at a position where the photosensor 302b can be shielded.

  Here, when the upper surface of the uppermost sheet Sa is positioned at a predetermined height, the sensor flag 302a rotates and the photosensor 302b is shielded from light. 3 is a control block diagram of the sheet feeding apparatus 51 according to the present embodiment. In FIG. 3, reference numeral 70 denotes a control unit. Connected to the control unit 70 is the sheet leading edge detection sensor 51c and the paper surface height detection means 302 as well as the first driving means 203, a positive voltage supply means 205a, a negative voltage supply means 205b, and a timer 71, which will be described later. Is done.

  Then, the control unit 70 detects the upper surface position of the uppermost sheet Sa by detecting the light shielding state of the photosensor 302b. Then, the control unit 70 controls the operation of the elevating unit 301 so that the upper surface of the uppermost sheet Sa is always detected by the paper surface height detecting unit 302, and the position of the middle plate 301a is set to the upper surface height of the uppermost sheet Sa. Is kept at a substantially constant position. As a result, the gap Lrgap between the nipping and conveying inner roller 501a and the upper surface of the uppermost sheet Sa is also kept substantially constant.

  The nipping / conveying inner roller 501a is disposed inside the adsorption member 410, and is rotatably supported by a shaft support member (not shown) whose arrangement position is fixed. In addition, a driving force is transmitted from the first driving unit 203 to the nipping and conveying inner roller 501a through a driving transmission unit (not shown). The nipping / conveying outer roller 501b is arranged outside the nipping / conveying inner roller 501a with the adsorbing member 410 interposed therebetween, and is rotatably supported by a shaft support member (not shown) to which a pressing spring 501c is connected. The nipping / conveying outer roller 501b is urged toward the axial center of the nipping / conveying inner roller 501a by a pressing spring 501c.

  The adsorption member 410 has an endless shape, and includes a positive electrode 410a and a negative electrode 410b shown in FIG. As shown in FIG. 2, a high voltage contact 205f to which a positive voltage is supplied and a high voltage contact 205g to which a negative voltage is supplied are electrically connected to the positive electrode 410a and the negative electrode 410b. Then, an electrostatic attracting force that attracts the sheet S is generated on the attracting member 410 by the applied voltage supplied from the high-voltage contacts 205f and 205g. The positive high-voltage contact 205f and the negative high-voltage contact 205g are connected to switches 205c and 205d for controlling the respective voltage supply.

  Here, in the present embodiment, when adsorbing and conveying the sheet to the adsorbing member 410, the adsorbing member 410 is elastically deformed after adsorbing the sheet to the adsorbing member 410 so that the sheets do not rub against each other. It is trying to pull it upwards. Then, the sheet is separated from other sheets by pulling upward while elastically deforming the suction member 410 in this way. Therefore, in the present embodiment, the length of the adsorption member 410 is determined so as to secure a sheet contact area Mn shown in FIG. ing.

  In FIG. 2, reference numeral 206 denotes a suction member position detection sensor. The adsorption member position detection sensor 206 detects a protrusion 410g shown in FIG. 5 (described later) provided on the adsorption member 410, and detects the rotation position of the adsorption member 410 by detecting the protrusion 410g. . In the present embodiment, the suction member position detection sensor 206 is a non-contact reflective photosensor, which irradiates a detection target with spot light and measures the amount of reflected light to detect the presence or absence of the detection target.

Reference numerals 204a and 204b denote guide pairs which are disposed between the sheet suction separation feeding unit 51b and the drawing roller pairs 51d and 51e and extend in the vertical direction. Guide to pair 51d, 51e. As shown in FIG. 4, the adsorbing member 410 includes a base layer 410c, a positive electrode 410a, and a negative electrode 410b. Inside the base layer 410c, a comb-shaped positive electrode and a comb-shaped negative electrode 410b are formed. Alternatingly arranged. In the present embodiment, the base layer 410c is a polyimide which is a dielectric having a volume resistance of 10 ⁸ Ωcm or more, and the layer thickness is about 100 μm. The positive electrode 410a and the negative electrode 410b are conductors having a volume resistance of 10 ⁶ Ωcm or less, and copper having a layer thickness of about 10 μm is used.

  As shown in FIG. 5, exposed areas 410 h and 410 i where the positive electrode and the negative electrode are exposed are provided on the back surface of the adsorption member 410. The positive high voltage contact 205f shown in FIG. 2 connected to the positive voltage supply means is connected to the positive electrode exposed area 410h, and the negative voltage supply means is connected to the negative electrode exposed area 410i. The negative high-voltage contacts 205g are in contact with each other.

  In the present embodiment, each of the positive high-voltage contact 205f and the negative high-voltage contact 205g has a structure in which a carbon brush is caulked at the tip of an elastic metal plate, and the carbon brush contacts the exposed regions 410h and 410i. ing. Since the positive high-voltage contact 205f and the negative high-voltage contact 205g have elasticity, stable feeding can be performed following the adsorption member 410 whose cross-sectional shape changes from moment to moment.

  Further, as shown in FIG. 5, the suction member 410 is formed with a straight portion 410 m and a curved portion 410 n along the circumferential direction. The reinforcing material 410p is coupled only to the straight portion 410m of the base layer 410c constituting the entire circumferential direction of the adsorption member 410, and a protrusion 410g is formed on a part of the end surface of the curved portion 410n of the adsorption member 410. ing.

  Next, the detailed configuration of the suction member 410 and the principle of generation of the suction force by which the suction member 410 sucks the sheet S will be described with reference to FIG. 4A is a diagram showing the surface of the adsorption member, FIG. 4B is a perspective view of the adsorption member 410, FIG. 4C is a diagram showing a cross section of the feeding portion of the adsorption member 410, and FIG. (D) is a diagram showing the concept of electrostatic attraction force acting between the attraction member 410 and the sheet S.

  In the present embodiment, as will be described later, when the suction member 410 approaches the sheet S, the material and thickness of the suction member 410 are adjusted so that the suction member 410 is bent downward to form a barrel shape. Has moderate elasticity. Exposed areas 410d and 410e, which are conductive portions from which the positive electrode 410a and the negative electrode 410b are exposed, are provided on the inner peripheral surface of the adsorption member 410 facing the nipping and conveying inner roller 501a and the nipping and conveying outer roller 501b. Then, the exposed region 410d of the positive electrode 410a, which is one of the electrodes, is connected to the positive voltage supply means 205a, which is a first power source for applying a positive voltage to the positive electrode 410a, via the switch 205c shown in FIG. The high voltage contact 205f is in contact. The negative electrode 410b, which is the other electrode, is connected to the exposed region 410e via a switch 205d shown in FIG. 2 and a negative voltage supply unit 205b, which is a second power source that applies a negative voltage to the negative electrode 410b. The high voltage contact 205g is in contact.

  In the present embodiment, a positive voltage of about +1 kV is applied to the positive electrode 410a, and a negative voltage of about -1 kV is applied to the negative electrode 410b. The high-voltage contact 205f and the high-voltage contact 205g each have a structure in which a carbon brush is caulked at the tip of an elastic metal plate, and the carbon brush contacts the exposed areas 410d and 410e of the positive electrode 410a and the negative electrode 410b. ing. Since the high-voltage contact 205f and the high-voltage contact 205g have elasticity, the high-voltage contact 205f and the high-voltage contact 205g can follow the suction member 410 whose cross-sectional shape changes from time to time, and can stably supply power.

  Here, as shown in FIG. 4D, when positive and negative voltages are applied to the positive electrode 410a and the negative electrode 410b, the positive electrode 410a and the negative electrode 410b to which the voltage is applied cause the adsorption member 410 to move. An unequal electric field is formed near the surface. When the suction member 410 formed with such an unequal electric field is brought close to the sheet S, dielectric polarization occurs in the surface layer of the dielectric material, and the Maxwell stress causes a gap between the suction member 410 and the sheet S. Electrostatic attraction force is generated in

  Next, the sheet feeding operation of the sheet adsorption separation feeding unit 51b according to the present embodiment will be described. FIG. 6A shows an initial operation of arranging the suction member 410 at the initial position of the feeding operation. By this operation, the suction member 410 becomes a position where the protrusion 410g is detected by the suction member position detection sensor 206. Further, by this operation, the adsorbing member 410 is in a state in which the curved portion 410n is sandwiched by the sandwiching and conveying roller pair 501 and is separated from the uppermost sheet Sa by a predetermined gap Lbgap. At this time, the first drive means 203 is stopped, and the switches 205c and 205d are in a non-energized state.

  FIG. 6B shows an approach operation in which the first driving unit 203 is operated to cause the suction member 410 to be conveyed downstream of the sheet conveyance via the pair of nipping conveyance rollers 501 and to approach the sheet. During this operation, the control unit 70 activates the first driving unit 203 to rotate the nipping and conveying roller pair 501 in the direction of arrow F. When the nipping and conveying roller pair 501 is thus rotated, the curved portion 410n of the suction member 410 approaches the uppermost sheet Sa.

  FIG. 6C shows a contact area increasing operation in which the approaching operation is continued to bring the surface of the suction member 410 into contact with the uppermost sheet Sa stacked to increase the contact area Mc. . During this operation, the controller 70 increases the contact area Mc by rotating the nipping and conveying roller pair 501 in the direction of arrow F and transporting the suction member 410 in the direction of arrow F, as in the approaching operation. . This contact area increasing operation is continued until the contact area Mc becomes equal to the predetermined sheet contact area Mn shown in FIG.

  FIG. 6D shows a state in which the uppermost sheet Sa is adsorbed in a state where the linear conveying portion 410m of the adsorbing member 410 is nipped by the nipping and conveying roller pair 501 and the surface of the adsorbing member 410 is in surface contact with a predetermined sheet contact area Mn. The adsorption operation to be performed is shown. In this operation, the control unit 70 turns on the switches 205c and 205d. As a result, a voltage is applied to the suction member 410 via the high-voltage contacts 205f and 205g, and an electrostatic suction force acts between the suction member 410 and the sheet Sa. In the present embodiment, when the sheet contact area becomes Mn, the first driving unit 203 is stopped for a certain time.

  FIG. 6E shows that the sheet Sa adsorbed on the adsorbing member 410 is separated from the stacked next sheet Sb by nipping and conveying the linear portion 410m of the adsorbing member 410 by the nipping and conveying roller pair 501. The separation operation to be performed is shown. During this operation, the control unit 70 operates the first driving unit 203 and pulls the suction member 410 upward while the uppermost sheet Sa is sucked by the pair of nipping and conveying rollers 501. At this time, the pair of nipping and conveying rollers 501 sandwich the straight portion 410m of the suction member 410, so that the sheet Sa sucked by the suction member 410 is linearly pulled up and stacked as indicated by an arrow A. Separated from the next sheet Sb.

  FIG. 6F shows a conveying operation in which the suction member 410 is conveyed by the operation of the first driving unit 203 after the separation operation, and the uppermost sheet Sa is adsorbed and conveyed to the drawing roller pairs 51d and 51e. . Here, when the leading edge of the uppermost sheet Sa is conveyed downstream from the nipping portion formed by the nipping and conveying roller pair 501, the leading edge of the uppermost sheet Sa is peeled from the suction member 410 by the guide pair 204a. Thereafter, although the separation of the uppermost sheet Sa increases from the leading edge, the uppermost sheet Sa is conveyed as it is by suction of the trailing edge region, and is passed to the drawing roller pairs 51d and 51e through the leading edge detection by the sheet leading edge detection sensor 51c. .

  This conveying operation is continued until the trailing edge of the uppermost sheet Sa is detected by the sheet leading edge detection sensor 51c, and when the suction member 410 returns to the initial position shown in FIG. Stop. If no sheet Sa is detected by the sheet leading edge detection sensor 51c, it is determined that an error has occurred in the feeding operation of the uppermost sheet Sa, and the feeding operation is restarted from the initial operation. Through the above six processes, only one sheet is fed from the plurality of sheets S stacked on the cassette 51a. If these six steps are repeated, the sheets S can be continuously fed one by one.

  FIG. 7 is a timing chart of the initial operation, the approach operation, the contact area increasing operation, the suction operation, the separation operation, and the transport operation shown in FIG. Here, a configuration in which the long side of the A4 size sheet S is conveyed as the leading end and the circumferential length of the suction member 410 is 100 mm is shown as an example. That is, in the present embodiment, since the length of the sheet S in the sheet feeding direction is 210 mm, the sheet S can be fed by the rotation of the suction member 410 slightly more than two rotations.

  In FIG. 7, a section from time T0 to T1 shown in (a) is an initial operation section, and at this time, the conveyance speed u is set to 0, the supply voltage vp, and the supply voltage vn are set to 0 (non-energized state). . Further, the suction member position detection sensor 206 is detected, and the sheet leading edge detection sensor 51c is not detected. Further, a section from time T1 to T3 shown in (b) is an approaching operation section, U is set as the conveyance speed at time T1, and the suction member position detection sensor 206 is in a non-detection state at time T2.

  The section from time T3 to T4 shown in (c) is a contact area increasing operation section, and the speed U is set as the transport speed u continuously from time T1. The section from time T4 to T5 shown in (d) is an adsorption operation section. At time T4, the transport speed u is set to 0, and the supply voltage vp and the supply voltage vn are set to + V and −V, respectively. The section from time T5 to T6 shown in (e) is a separation operation section. At time T5, U is set as the conveyance speed u, and the supply voltage vp is continuously + V and the supply voltage vn from time T4. -V is set for each.

  The section from time T6 to time T10 shown in (f) is a transport operation section, U is set for the transport speed u, + V is set for the supply voltage vp, and -V is set for the supply voltage vn. At time T7, the sheet leading edge detection sensor 51c is in a detection state, and the suction member 410 can convey the sheet S with a little more than two rotations. Therefore, after the suction member position detection sensor 206 enters the detection state twice, At time T8, the sheet leading edge detection sensor 51c enters a non-detection state.

  When the suction member position detection sensor 206 is in a detection state at time T9, the transport speed u, supply voltage vp, and supply voltage vn are all set to 0 at time T10. In addition, the control unit 70 determines the feeding retry depending on whether or not the time T7 is within a predetermined value range. From time T10 to time T11 shown in (a), an initial operation is performed to prepare for the next sheet S feeding. Thereafter, if the above is repeated, continuous sheet feeding is performed.

  In the present embodiment, the straight portion 410m of the adsorbing member 410 is formed by adding the reinforcing material 410p to the base layer 410c. However, even if the base layer 410c is molded into the shape of the straight portion 410m and the curved portion 410n, Similar effects can be obtained. Further, the straight portion 410m and the curved portion 410n may be formed of materials having different hardness.

  Furthermore, in the present embodiment, an electrostatic attracting force is generated between the attracting member 410 and the sheet S in the configuration as described above, but the present embodiment is not limited to this. For example, the positive electrode 410a and the negative electrode 410b do not have to have a comb-teeth shape, and may have a shape like a uniform electrode in which an electric field is formed between the sheet S and the sheet S can be dielectrically polarized.

  As described above, in this embodiment, the suction member 410 is brought into surface contact with the sheet to suck the sheet, the separation position where the sucked sheet is separated from the lower sheet while being bent, and sucked. It is possible to move to a separation position where the sheet is separated. Further, the suction member 410 is rotated to suck the sheet, and after the sucked sheet is delivered to the pair of drawing rollers 51d and 51e, the suction member 410 is stopped at a position away from the sheet (standby position). .

  Furthermore, in the present embodiment, the adsorbing member 410 is constituted by a straight portion 410m and a curved portion 410n. Then, after the suction member 410 is moved to the suction position where the curved portion 410n comes into surface contact with the sheet by the rotation of the nipping and conveying roller pair 501, the straight portion 410m lifts the suction member 410 toward the drawing roller pairs 51d and 51e while eliminating the bending. I am doing so. Thus, even when the drawing roller pair 51d, 51e is arranged above the suction member 410, if the suction member 410 is rotated, the sucked sheet can be delivered to the drawing roller pair 51d, 51e arranged above. it can. As a result, the sheet can be stably fed by electrostatic attraction with a simple configuration and low noise. In addition, the length of the sheet feeding device in the sheet feeding direction can be shortened.

  In the present embodiment described above, the configuration in which the adsorbing member 410 includes the straight portion 410m and the curved portion 410n has been described, but the present invention should not be limited to this. In other words, the present invention may be configured so that the adsorbing member 410 includes the first portion and the second portion having a larger curvature than the first portion. Thereby, a sheet | seat can be adsorb | sucked by a 2nd part and a sheet | seat can be conveyed upwards by a 1st part. In order to convey the sheet upward, it is preferable that the first portion has a substantially linear shape.

  Next, a second embodiment of the present invention will be described. FIG. 8 is a diagram illustrating the configuration of the sheet feeding apparatus according to the present embodiment. In FIG. 8, the same reference numerals as those in FIG. 2 described above indicate the same or corresponding parts.

  In FIG. 8, 461 is a first nipping and conveying roller pair, 462 is a second nipping and conveying roller pair, and 460 is a flexible material nipped and conveyed by the first nipping and conveying roller pair 461 and the second nipping and conveying roller pair 462. It is an endless adsorption member. A first nipping and conveying roller pair 461 and a second nipping and conveying roller pair 462, which are a plurality of nipping and conveying members provided along the sheet feeding direction, have a predetermined gap Lrgap from the upper surface of the uppermost sheet Sa stacked on the cassette 51a. It is arranged with. Further, the second nipping / conveying roller pair 462 that is the second nipping / conveying member is disposed upstream of the first nipping / conveying roller pair 461 that is the first nipping / conveying member.

  The first nipping / conveying roller pair 461 includes a first nipping / conveying inner roller (first rotating body) 461a and a first nipping / conveying outer roller (first nipping member) 461b. The second nipping / conveying roller pair 462 includes a second nipping / conveying inner roller (second rotating body) 462a and a second nipping / conveying outer roller (second nipping member) 462b. The first nipping and conveying inner roller 461a is disposed inside the suction member 460, and is rotatably supported by a shaft support member (not shown) whose position is fixed. In addition, a driving force is transmitted from the first driving unit 203 to the first nipping and conveying inner roller 461a via a driving transmission unit (not shown).

  The first nipping / conveying outer roller 461b is disposed outside the first nipping / conveying inner roller 461a with the adsorbing member 460 interposed therebetween, and is rotatably rotated by a shaft support member (not shown) connected to the first pressing spring 461c. It is supported. The first nipping / conveying outer roller 461b is urged toward the axial center of the first nipping / conveying inner roller 461a by a first pressing spring 461c.

  The second nipping / conveying inner roller 462a is disposed inside the adsorption member 460 similarly to the first nipping / conveying inner roller 461a, and is rotatably supported by a shaft support member (not shown) having a fixed arrangement position. A driving force is transmitted from the second driving means 204 to the second nipping and conveying inner roller 462a via a driving transmission means (not shown).

  Similar to the first nipping and conveying roller 461b, the second nipping and conveying outer roller 462b is disposed outside the second nipping and conveying inner roller 462a with the adsorption member 460 interposed therebetween, and is not connected to the second pressing spring 462c. It is rotatably supported by the illustrated shaft support member. The second nipping / conveying outer roller 462b is urged toward the axial center of the second nipping / conveying inner roller 462a by a second pressing spring 462c.

  The adsorption member 460 is wound around the first nipping and conveying roller pair 461 and the second nipping and conveying roller pair 462, and is longer than the shortest length that can be wound around the first nipping and conveying roller pair 461 and the second nipping and conveying roller pair 462. It has a length. By having such a length, although there is a gap between the first nipping and conveying roller pair 461 and the second nipping and conveying roller pair 462 and the upper surface of the uppermost sheet, the adsorbing member 460 can be It is possible to contact the upper surface of the upper sheet Sa.

  A positive voltage supply unit 205a and a negative voltage supply unit 205b are electrically connected to the suction member 460, and the sheet S is attracted to the suction member 460 by the applied voltages from the positive and negative voltage supply units 205a and 205b. An electrostatic attraction force is generated. Switches 205c and 205d for controlling voltage supply are connected to the positive high-voltage contact 205f and the negative high-voltage contact 205g, respectively.

  In FIG. 8, reference numeral 463 denotes a first suction member position detection sensor, 464 denotes a second suction member position detection sensor, and the first and second suction member position detection sensors 463 and 464 denote suction shown in FIG. The projections 460j and 460k of the member 460 are detected. Then, the first and second suction member position detection sensors 463 and 464 detect the protrusions 460j and 460k of the suction member 460, thereby detecting the rotational position of the suction member 460. In the present embodiment, the first and second suction member position detection sensors 463 and 464 are non-contact reflection type photosensors. The detection target is irradiated with spot light, and the amount of reflected light is measured to detect the detection target. The presence or absence of is detected.

  As shown in FIG. 9, the adsorbing member 460 is formed with linear portions 460a and 460b and curved portions 460c and 460d facing each other along the circumferential direction. The reinforcing members 460f and 460g are coupled only to the straight portions 460a and 460b of the base layer (base material) 460e constituting the entire circumferential direction of the adsorption member 460.

  In addition, exposed regions 460h and 460i in which the positive electrode and the negative electrode are exposed are provided inside the adsorption member 460, and protrusions 460j and 460k are formed on part of the end surface of the adsorption member 460. ing. Here, the positive high voltage contact 205f connected to the positive voltage supply means shown in FIG. 8 is connected to the exposed area 460h of the positive electrode, and the negative voltage supply means is connected to the exposed area 460i of the negative electrode. The negative high voltage contacts 205g are in contact with each other. In the present embodiment, positive and negative voltages of about 1 kV are applied to the positive electrode and the negative electrode, respectively.

  Next, the sheet feeding operation of the sheet adsorption separation feeding unit 51b according to the present embodiment will be described. FIG. 10A shows an initial operation of arranging the suction member 460 at the initial position of the feeding operation. By this operation, the suction member 460 is in a position where the protrusions 460j and 460k are detected by the first and second suction member position detection sensors 463 and 464, respectively. Also, by this operation, the adsorbing member 460 has the curved portions 460c and 460d sandwiched by the first sandwich transport roller pair 461 and the second sandwich transport roller pair 462, respectively, and separated from the uppermost sheet Sa by a predetermined gap Lbgap. It has become a state. At this time, the first drive means 203 and the second drive means 204 are stopped, and the switches 205c and 205d are in a non-energized state.

  In FIG. 10B, the first driving unit 203 and the second driving unit 204 are operated, and the suction member 460 is moved downstream in the sheet feeding direction via the first nipping and conveying roller pair 461 and the second nipping and conveying roller pair 462. The approaching action is shown in which the sheet is conveyed to and moved closer to the sheet. During this operation, the controller 70 activates the first driving unit 203 and the second driving unit 204 to rotate the first nipping and conveying roller pair 461 and the second nipping and conveying roller pair 462 in the direction of arrow F. When the first nipping and conveying roller pair 461 and the second nipping and conveying roller pair 462 are rotated in this way, the curved portion 460d (or 460c) of the suction member 460 approaches the uppermost sheet Sa.

  FIG. 10C shows a contact area increasing operation in which such an approaching operation is continued to bring the surface of the suction member 460 into contact with the uppermost sheet Sa stacked to increase the contact area Mc. . During this operation, the controller 70 conveys the suction member 460 in the direction of the arrow F as in the approach operation, and continues until the contact area Mc becomes equal to the predetermined sheet contact area Mn. In this embodiment, the linear portion 460a (or 460b) of the suction member 460 is sandwiched by the first sandwiching conveyance roller pair 461, and the curved portion 460d (or 460c) of the suction member 460 is in surface contact with the sheet Sa. Then, the first driving means 203 is stopped.

  Then, by continuously driving only the second driving unit 204, the contact area Mc is increased. Further, when the switches 205c and 205d are energized, a voltage is applied via the positive voltage supply means 205a and the negative voltage supply means 205b of the suction member 460, so that the gap between the suction member 460 and the uppermost sheet Sa. The electrostatic attraction force works.

  FIG. 10D shows that the straight portion 460a (or 460b) of the suction member 460 is sandwiched between the first and second pair of nipping and conveying rollers 461 and 462, and the surface of the suction member 460 has a predetermined sheet contact area Mn. An adsorption operation for adsorbing the sheet Sa in a contact state is shown. At the time of this operation, the control unit 70 stops the second driving unit 204 together with the first driving unit 203 for a predetermined time in a state where the sheet is contacted and attracted with a predetermined sheet contact area Mn.

  In FIG. 10E, the uppermost sheet Sa is stacked by conveying the suction member 460 that has adsorbed the uppermost sheet Sa by the first nipping and conveying roller pair 461 and the second nipping and conveying roller pair 462. The separation operation for separating from the next sheet Sb is shown. In this operation, the controller 70 first operates the first driving unit 203 after the above-described suction operation, and then operates the second driving unit 204 after a predetermined time.

  As a result, the first nipping and conveying roller pair 461 nipping and conveying the linear portion 460a of the adsorption member 460, so that the uppermost sheet Sa adsorbed by the adsorption member 460 is pulled up linearly as indicated by an arrow A. Then, it is separated from the stacked next sheet Sb. In the present embodiment, the two straight portions 460a and 460b are provided facing each other in the circumferential direction. As a result, when the straight portion 460 a of the suction member 460 is sandwiched between the first sandwich conveyance roller pair 461, the other straight portion 460 b is also sandwiched between the second sandwich conveyance roller pair 462. Thereby, the adsorption | suction member 460 can be pulled up reliably.

  FIG. 10 (f) shows a transport operation in which the suction member 460 is transported by the operations of the first drive means 203 and the second drive means 204 after the separation operation described above, thereby attracting and transporting to the drawing roller pairs 51d and 51e. Is shown. At this time, the uppermost sheet Sa remains adsorbed by the adsorbing member 460, and the uppermost sheet Sa is conveyed together with the adsorbing member 460 while being separated and separated from the stacked next sheet Sb.

  When the leading edge of the uppermost sheet Sa is conveyed downstream from the nipping portion formed by the first sandwiching and conveying roller pair 461, the leading edge of the uppermost sheet Sa is peeled off from the suction member 460 by the guide pair 204a. Thereafter, although the separation of the uppermost sheet Sa increases from the leading edge, the uppermost sheet Sa is conveyed as it is by suction of the trailing edge region, and is passed to the drawing roller pairs 51d and 51e through the leading edge detection by the sheet leading edge detection sensor 51c. . This conveyance operation continues until the trailing edge of the uppermost sheet Sa is detected by the sheet leading edge detection sensor 51c, and then stops when the suction member 460 returns to the initial position shown in FIG. If no sheet Sa is detected by the sheet leading edge detection sensor 51c, it is determined that an error has occurred in the feeding operation of the uppermost sheet Sa, and the feeding operation is restarted from the initial operation. Through the above six processes, only one sheet is fed from the plurality of sheets S stacked on the cassette 51a. If these six steps are repeated, the sheets S can be continuously fed one by one.

  FIG. 11 is a timing chart in the feeding operation for one sheet of the sheet suction separation feeding unit 51b described in FIG. In the present embodiment, a configuration in which the long side of the A4 size sheet S is conveyed with the leading edge and the circumferential length of the suction member 460 is 410 mm is shown as an example. That is, in the present embodiment, since the length of the sheet S in the sheet feeding direction is 210 mm, the sheet S can be fed by rotating the suction member 410 slightly more than one rotation.

  In FIG. 11, a section from time T0 to T1 shown in FIG. 11A is an initial operation section, in which the first and second suction member position detection sensors 463 and 464 are detected, and the sheet leading edge detection sensor 51c is not detected. It is. Further, 0 (stopped state) is set for the transport speed u1 and transport speed u2, and 0 (non-energized state) is set for the supply voltage vp and the supply voltage vn. The section from time T1 to T3 shown in (b) is an approaching operation, U is set for the transport speed u1 and transport speed u2 at time T1, and the first and second suction member position detection sensors 463 at time T2. 464 becomes a state of no detection.

  In FIG. 11, the section from time T3 to T5 shown in (c) is the contact area increasing operation. Then, the speed U is set for the transport speed u1 and the transport speed u2 continuously from the time T1, but only the transport speed u1 is set to 0 at the time T4, and the supply voltage vp is + V and the supply voltage vn. -V is set for each. The section from time T5 to T6 shown in (d) is an adsorption operation, and the transport speed u2 is set to 0 at time T5. The section from time T6 to T7 shown in (e) is a separation operation, and the speed U is set as the transport speed u1 at time T6.

  In FIG. 11, the section from time T7 to T11 shown in (f) is a transport operation, and at time T7, the speed U is set as the transport speed u2. At time T8, the sheet leading edge detection sensor 51c is in a detection state. Next, since the suction member 460 can convey the uppermost sheet Sa with a little more than one rotation, after the first and second suction member position detection sensors 463 and 464 enter the detection state twice, at time T9, The sheet leading edge detection sensor 51c is not detected.

  When the first and second suction member position detection sensors 463 and 464 are in a detection state at time T10, at time T11, all of the transport speed u1, the transport speed u2, the supply voltage vp, and the supply voltage vn are 0. Is set. Further, the control unit 70 determines the feeding retry depending on whether or not the time T8 is within a predetermined value range. From time T11 to T12 shown in (a), the initial operation is performed again to prepare for the feeding of the next sheet S. Thereafter, if the above is repeated, continuous sheet feeding is performed.

  As described above, in this embodiment, the suction member 460 is nipped and conveyed by the first nipping and conveying roller pair 461 and the second nipping and conveying roller pair 462. And by comprising in this way, the adsorption | suction area of the adsorption | suction member 460 and the sheet | seat S can be expanded, and reliable conveyance force can be obtained. In the present embodiment, the reinforcing members 460f and 460g are joined only to the straight portions 460a and 460b of the base layer (base material) 460e, whereby the rigidity of the straight portions 460a and 460b is changed to the curved portions 460d and 460c. It is larger than the rigidity. However, the present embodiment is not limited to this, and the straight portions 460a and 460b of the adsorption member 460 may be configured by other members having higher rigidity than the curved portions 460d and 460c.

  Next, a third embodiment of the present invention will be described. FIG. 12 is a diagram illustrating the configuration of the sheet feeding apparatus according to the present embodiment. In FIG. 12, the same reference numerals as those in FIG. 8 described above indicate the same or corresponding parts.

  In FIG. 12, reference numeral 470 denotes a suction member, and 250a denotes a charging roller that is provided above the suction member 470 and is a voltage application member that presses the suction member 470 from above. The charging roller 250a is rotatably supported by an unillustrated shaft support member whose arrangement position is fixed, and is driven to rotate as the suction member 470 moves. An AC power source 252 is connected to the charging roller 250a. As a result, the surface of the adsorption member 470 is charged by contact charging by the charging roller 250a, and an electrostatic adsorption force that attracts the sheet S by the applied charge is generated. Reference numeral 250b denotes a backup roller that is provided at a position corresponding to the charging roller 250a on the inner peripheral surface of the suction member 470 so as to stably contact the charging roller 250a and the suction member 470, and press-contacts the suction member 470 from below. is there.

  Simultaneously with the conveying operation of the suction member 470, an alternating voltage is applied from the charging roller 250a pressed against the surface of the suction member 470. As a result, the surface of the adsorbing member 470 is positively charged at intervals according to the frequency of the AC power supply 252 and the surface moving speed of the adsorbing member 470, as shown in FIGS. 13 (a) and 13 (b). The formed region and the negatively charged region are formed in stripes. An unequal electric field is formed in the vicinity of the surface of the adsorption member 470 by the positive and negative charging regions formed alternately in stripes. When the suction member 470 formed with an unequal electric field in this manner is brought close to the sheet S, dielectric polarization occurs in the sheet surface layer, which is a dielectric, and the Maxwell stress causes the suction member 470 between the suction member 470 and the sheet S. Electrostatic adsorption force is generated.

  Thus, in the present embodiment, the sheet adsorbing force can be obtained by externally charging the surface of the adsorbing member by the charging roller 250a. As a result, since the adsorption member 470 can be charged without disposing an electrode inside the adsorption member, the structure of the adsorption member 470 can be simplified and the cost can be reduced.

  In the embodiment described so far, the sheet S is attracted to the attracting member by the electrostatic attracting force, but the present invention is not limited to this. For example, a fine fiber structure of submicron order may be formed on the adsorbing member and adsorbed by an intermolecular attractive force acting between the sheet S.

51, 52 ... sheet feeding device, 51a ... cassette, 51b, 52b ... sheet suction separation feeding unit, 51c ... sheet leading edge detection sensor, 51d, 51e ... drawing roller pair, 55 ... image forming unit, 70 ... control unit, DESCRIPTION OF SYMBOLS 100 ... Image forming apparatus, 100A ... Image forming apparatus main body, 203 ... 1st drive means, 204 ... 2nd drive means, 205 ... Power supply unit, 205a ... Positive voltage supply means, 205b ... Negative voltage supply means, 206 ... Adsorption member Position detection sensor, 250a ... charging roller, 252 ... AC power supply, 410 ... adsorption member, 410a ... positive electrode, 410b ... negative electrode, 410g ... projection, 410m ... straight part, 410n ... curved part, 410p ... reinforcing material, 460 ... Adsorption member, 460a, 460b ... Linear part, 460c, 460d ... Curved part, 460j, 460k ... Projection part, 461 ... First clamping Roller pair, 462 ... second nipping and conveying roller pair, 463 ... first adsorbing member position detection sensor, 464 ... second adsorbing member position detection sensor, 470 ... adsorption member, 501 ... nipping and conveying roller pair, 501a ... nipping and conveying inner roller , 501b: Nipping and conveying outer roller, Mn: Sheet contact area, S: Sheet, Sa: Top sheet

Claims (11)

A stacking means on which sheets are stacked;
A first rotating body disposed above the stacking means;
An inner surface is supported by the first rotating body, and has a first portion and a second portion having a larger curvature than the first portion, and electrically adsorbs the sheets stacked on the stacking means. An adsorbing member;
A first clamping member that clamps the suction member together with the first rotating body;
First driving means for rotating the first rotating body and the first clamping member;
Control means for controlling the first drive means,
The sheet feeding device according to claim 1, wherein the control unit adsorbs the sheets stacked on the stacking unit by the second part, and then conveys the sheet upward by the first part.   The suction member has flexibility, a standby position away from the sheets stacked on the stacking means, a suction position for sucking the sheets stacked on the stacking means, and a lower position by moving the sucked sheets upward 2. The sheet feeding apparatus according to claim 1, wherein the sheet feeding apparatus is provided so as to be movable to a separation position for separating from the sheet and a separated position where the adsorbed sheet is separated from the adsorption member. A second rotating body provided upstream of the first rotating body in the sheet feeding direction;
A second clamping member for clamping the suction member together with the second rotating body;
Second driving means for rotating the second rotating body and the second clamping member,
The control means rotates only the second rotating body and the second holding member, and adsorbs the sheets stacked on the stacking means by the second portion, and then the first rotating body. 3. The sheet feeding device according to claim 1, wherein the sheet is conveyed upward by the first portion by rotating only the first clamping member. 4.   4. The sheet feeding apparatus according to claim 1, wherein the first portion of the suction member is formed by bonding a reinforcing material to a base material. 5.   The sheet feeding apparatus according to claim 1, wherein the first portion has a substantially straight shape. Having a power source for applying a voltage to the adsorbing member and applying an adsorbing force to adsorb the sheet by static electricity;
The adsorption member is provided with two electrodes,
The power supply includes a first power supply that applies a positive voltage to one of the two electrodes, and a second power supply that applies a negative voltage to the other of the two electrodes. 3. The sheet feeding apparatus according to 3. The adsorption member is provided with two electrodes,
The power source includes a first power source that applies a positive voltage to one of the two electrodes, and a second power source that applies a negative voltage to the other of the two electrodes,
Forming a conductive portion in the first clamping member or the second clamping member, connecting one of the first power source and the second power source to one of the two electrodes of the adsorption member via the conductive portion; The sheet feeding apparatus according to claim 6, wherein the other of the first power source and the second power source is connected to the other of the two electrodes of the suction member.   A voltage application member is provided between the suction member and the power source, and contacts the suction member before the suction member contacts the sheet to apply a voltage from the power source to the suction member. The sheet feeding apparatus according to claim 6 or 7.   9. The sheet feeding apparatus according to claim 8, wherein the power source is an AC power source.   The magnitude of the adsorption force due to static electricity when the adsorption member eliminates bending is set to a size such that the sheet is separated from the adsorption member due to the rigidity of the sheet. The sheet feeding apparatus according to any one of 1 to 9. An image forming unit for forming an image on a sheet;
An image forming apparatus comprising: the sheet feeding device according to claim 1, which feeds a sheet to the image forming unit.

Images