Patent Application
20160101951
The present invention relates to a sheet feeding device and an image forming apparatus, and more particularly, to a technique of feeding a sheet using electrostatic adsorption force.
An image forming apparatus such as a copying machine or a printer according to a related art includes a sheet feeding device that feeds a sheet, and as the sheet feeding device, there is a friction feed system in which a topmost sheet is separated and fed from a cassette on which a sheet bundle is loaded using frictional force of a rubber roller or the like. In the sheet feeding device of the friction feed system, the topmost sheet is fed by the rubber roller rotating while pressing the sheet bundle. Here, when a sheet is fed, multi-sheet feeding in which a plurality of sheets are conveyed by friction between sheets may occur. On the other hand, conveyance resistance works on the remaining sheets excluding the topmost sheet through a separating pad or a retard roller, and thus only the topmost sheet is fed to an image forming portion.
Meanwhile, in the sheet feeding device of the friction separation system, since the rubber roller feeds a sheet while applying great pressure to the sheet, noise generated by sliding friction between sheets or between the sheet and the rubber roller is problematic. In addition, when the multi-sheet feeding caused by the separating pad or the retard roller is prevented, sliding fricative between sheets is greatly generated. Further, since the separating pad or the retard roller serves as conveyance resistance of the topmost sheet even when the multi-sheet feeding does not occur, a sound is generated by stick slip between the separating pad or the retard roller and the sheet.
In this regard, as a technique of solving the problem, there is a sheet feeding device configured to separate and feed a sheet while adsorbing the sheet using electrostatic adsorption force, specifically, by an electric field formed on a belt surface (see Patent Literatures 1 and 2). In the sheet feeding device of the electrostatic adsorption separation system, since it is possible to convey the topmost sheet as if the topmost sheet is peeled off from the sheet bundle, it is possible to significantly reduce noise generated in a feeding portion.
However, in the sheet feeding device of the related art that feeds the sheet using electrostatic adsorption force, in a configuration of Patent Literature 1, it is possible to apply sufficient electrostatic adsorption force to the sheet, but when the sheet is separated, since lifting and lowering are performed for each frame on which the adsorbing belt is carried, an operation sound occurs. A collision sound with the sheet occurs as well. Further, when the sheet is adsorbed, belt tension is reduced by reducing an inter-axial distance so that a sheet can be adsorbed with certainty even when a sheet curls, that is, so that followability to the sheet curl can be secured when the adsorbing belt adsorbs the sheet. However, when the sheet is adsorbed in a state in which belt tension is reduced, it is necessary to increase tension at the time of the separation operation, and when the tension is increased as described above, string vibration occurs in the belt, and a sudden sound is caused by the vibration.
In a configuration of Patent Literature 2, the adsorbing belt is used, but since the sheet separation operation is performed by causing the carrying roller to perform an eccentric motion instead of lifting and lowering the adsorbing belt for each frame, a machinery operation sound is reduced. However, when the adsorbing belt comes into contact with the sheet bundle with certainty, the roller collides with the sheet bundle through the adsorbing belt, and thus a collision sound still occurs. Further, when an attempt to prevent a collision between the roller and the sheet bundle is made, the belt is separated from the sheet bundle, sheet adsorption by the adsorbing belt becomes unstable, leading to a feeding failure.
In this regard, in light of the foregoing, it is an object of the present invention to provide a sheet feeding device and an image forming apparatus, which are capable of stably performing sheet feeding by electrostatic adsorption at a low noise with a simple configuration.
The present invention provides a sheet feeding device which includes a loading unit that loads a sheet, a first rotating member that is arranged above the loading unit, an adsorbing member that includes a first portion and a second portion having a curvature larger than a curvature of the first portion and electrically adsorbs the sheet loaded on the loading unit, an inner side of the adsorbing member being supported by the first rotating member, a nip member that nips the adsorbing member together with the first rotating member, a first driving unit that rotates the first rotating member and the first nip member, and a control unit that controls the driving unit, wherein the control unit adsorbs the sheet loaded on the loading unit through the second portion and then conveys the sheet upward through the first portion.
According to the present invention, the adsorbing member that electrically adsorbs the sheet includes a first portion and a second portion having a curvature larger than a curvature of the first portion, and the adsorbing member adsorbs the sheet loaded on the loading unit through the second portion and then conveys the sheet upward through the first portion. Thus, it is possible to stably perform sheet feeding by electrostatic adsorption at a low noise with a simple configuration.
Hereinafter, embodiments of the present invention will be described in detail with reference to the appended drawings.
In
The image forming portion 55 includes an exposure unit 42 and four process cartridges 43 (43y, 43m, 43c, and 43k) for forming toner images of four colors, that is, yellow (Y), magenta (M), cyan (C), and black (Bk). The image forming portion 55 further includes an intermediate transfer unit 44, a secondary transfer portion 56, and a fixing portion 57 arranged above the process cartridge 43.
Here, the process cartridge 43 includes a photosensitive drum 21 (21y, 21m, 21c, and 21k), a charging roller 22 (22y, 22m, 22c, and 22k), and a developing roller 23 (23y, 23m, 23c, and 23k). The process cartridge 43 further includes a drum cleaning blade 24 (24y, 24m, 24c, and 24k).
The intermediate transfer unit 44 includes a belt driving roller 26, an intermediate transfer belt 25 stretching to an inner secondary transfer roller 56a or the like, and primary transfer roller 27 (27y, 27m, 27c, and 27k) that abuts the intermediate transfer belt 25 at a position opposite to the photosensitive drum 21. As will be described later, as transfer bias of a positive polarity is applied to the intermediate transfer belt 25 through the primary transfer roller 27, toner images having a negative polarity on the photosensitive drum 21 are sequentially multi-transferred onto the intermediate transfer belt 25. As a result, a full color image is formed on the intermediate transfer belt 25.
The secondary transfer portion 56 is configured with the inner secondary transfer roller 56a and an outer secondary transfer roller 56b that comes into contact with the inner secondary transfer roller 56a with the intermediate transfer belt 25 interposed therebetween. Further, as will be described later, as secondary transfer bias of a positive polarity is applied to the outer secondary transfer roller 56b, the full color image formed on the intermediate transfer belt 25 is transferred onto the sheet S.
The fixing portion 57 includes a fixing roller 57a and a fixing backup roller 57b. The sheet S is nipped and conveyed between the fixing roller 57a and the fixing backup roller 57b, and thus the toner image on the sheet S is pressed and heated, and then fixed onto the sheet S. The sheet feeding devices 51 and 52 include cassettes 51a and 52a, respectively, serving as a storage unit that stores the sheet S and sheet adsorption separation feeding portions 51b and 52b, respectively, having a function of feeding the sheets S one by one while adsorbing the sheet S stored in the cassettes 51a and 52a by static electricity.
In
Next, an image forming operation of the image forming apparatus 100 having the above configuration will be described. When the image forming operation starts, the exposure unit 42 first irradiates the surface of the photosensitive drum 21 with laser beams based on image information provided from a personal computer (not illustrated) or the like. At this time, the surface of the photosensitive drum 21 is uniformly charged to a predetermined polarity and potential by the charging roller 22, and when the laser beams are irradiated, charges of a portion irradiated with the laser beams are attenuated, and thus an electrostatic latent image is formed on the surface of the photosensitive drum.
Thereafter, the electrostatic latent image is developed by yellow (Y), magenta (M), cyan (C), and black (Bk) toners supplied from the developing roller 23, and thus the electrostatic latent image is visualized as toner images. Then, the toner images of the respective colors are sequentially transferred onto the intermediate transfer belt 25 by primary transfer bias applied to the primary transfer roller 27, and thus 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, in the sheet feeding devices 51 and 52, only one piece of sheet S is separated and fed from the cassettes 51a and 52a through the sheet adsorption separation feeding portions 51b and 52b. Thereafter, the sheet S is detected by sheet leading end detecting sensors 51c and 52c and reaches a pair of drawing rollers 51d and 51e. Further, the sheet S nipped between the pair of drawing rollers 51d and 51e is fed to the conveyance path 103 and abuts a pair of registration rollers 62a and 62b that is stopped, so that a position of the leading end thereof is adjusted.
Then, in the secondary transfer portion 56, the pair of registration rollers 62a and 62b are driven at a timing at which the full color toner image on the intermediate transfer belt matches the position of the sheet S. As a result, the sheet S is conveyed to the secondary transfer portion 56, and in the secondary transfer portion 56, the full color toner image is collectively transferred onto the sheet S through secondary transfer bias applied to the outer secondary transfer roller 56b.
The sheet S onto which the full color toner image has been transferred is conveyed to the fixing portion 57 and receives heat and pressure in the fixing portion 57, and the toners of the respective colors undergo melting and color mixture and are fixed as a full color image to the sheet S. Thereafter, the sheet S to which the image has been fixed is discharged through the discharge portion 58 installed in the downstream of the fixing portion 57. Further, when an image is formed on both sides of the sheet, the conveyance direction of the sheet S is reversed by the sheet reversing portion 59, so that the sheet S is conveyed to the image forming portion 55 again.
Next, a configuration of the sheet feeding device 51 according to the present embodiment will be described with reference to
The sheet adsorption separation feeding portion 51b includes a pair of nip conveying rollers 501 serving as a nip conveying member configured with an inner nip conveying roller (a first rotating member) 501a and an outer nip conveying roller 501 (a first nip member) b. The sheet adsorption separation feeding portion 51b further includes an endless adsorbing member 410 having flexibility nipped between the pair of nip conveying rollers 501, a first driving unit 203, and a power source unit 205. The pair of nip conveying rollers 501 is arranged to be apart from the top surface of the topmost sheet loaded on the cassette 51a by a predetermined gap Lrgap. The inner surface of the adsorbing member 410 is supported by the inner nip conveying roller 501a. In the present embodiment, the pair of drawing rollers 51d and 51e is arranged above the pair of nip conveying rollers 501. The sheet adsorption separation feeding portion 52b arranged in the sheet feeding device 52 has the same configuration as the sheet adsorption separation feeding portion 51b of the sheet feeding device 51, and thus a description thereof is omitted.
The lifting and lowering unit 301 includes a lifter 301b that is installed to be rotatable down the sheet supporting plate 301a, and changes the position of the sheet supporting plate 301a and the position of a topmost sheet Sa loaded on the sheet supporting plate 301a according to a rotation angle of the lifter 301b. The sheet leading end detecting sensor 51c is arranged in the sheet conveyance path between the sheet adsorption separation feeding portion 51b and the pair of drawing rollers 51d and 51e. Success or failure of sheet feeding is detected by detecting whether or not the sheet leading end detecting sensor 51c detects the sheet S at a predetermined timing. In the present embodiment, the sheet leading end detecting sensor 51c is a non-contact reflective photo sensor, and detects the presence or absence of a detection target by irradiating the detection target with spotlight and measuring reflected light quantity thereof.
In
Here, when the top surface of the topmost sheet Sa is positioned at a predetermined height, the sensor flag 302a rotates, and the photo sensor 302b is light-shielded.
Further, the controller 70 detects the position of the top surface of the topmost sheet Sa by detecting the light-shielding state of the photo sensor 302b. The controller 70 controls an operation of the lifting and lowering unit 301 such that the top surface of the topmost sheet Sa is consistently detected by the plane of paper height detecting unit 302, and maintains the position of the sheet supporting plate 301a to be a position at which the height of the top surface of the topmost sheet Sa is almost constant. As a result, a gap Lrgap between the driving roller 401 and the top surface of the topmost sheet Sa is maintained to be almost constant.
The inner nip conveying roller 501a is arranged inside the adsorbing member 410 and rotatably shaft-supported by a shaft support member (not illustrated) whose arrangement position is fixed. Further, driving force is transmitted from the first driving unit 203 to the inner nip conveying roller 501a through a driving transmission unit (not illustrated). The outer nip conveying roller 501b is arranged outside the inner nip conveying roller 501a with the adsorbing member 410 interposed therebetween and rotatably shaft-supported by a shaft support member (not illustrated) to which a pressing spring 501c is connected. The outer nip conveying roller 501b is biased in a shaft center direction of the inner nip conveying roller 501a by the pressing spring 501c.
The adsorbing member 410 has an endless shape, and includes a positive electrode 410a and a negative electrode 410b illustrated in
Here, in the present embodiment, when the adsorbing member 410 adsorbs and conveys the sheet, the adsorbing member 410 adsorbs the sheet by the static electricity so that the sheets do not undergo sliding friction, and then the adsorbing member 410 is pulled up while being elastically deformed. As the adsorbing member 410 is pulled up while being elastically deformed as described above, the sheet is separated from another sheet. In this regard, in the present embodiment, the length of the adsorbing member 410 is decided so that a sheet contact area Mn (which will be described later) illustrated in (d) of
In
204
a and 204b are a pair of guides that is arranged between the sheet adsorption separation feeding portion 51b and the pair of drawing rollers 51d and 51e and stretch vertically, and guide the sheet S conveyed by the adsorbing member 410 to the pair of drawing rollers 51d and 51e thereabove. As illustrated in
Exposed regions 410h and 410i in which the positive electrode and the negative electrode are exposed are formed on the back surface of the adsorbing member 410 as illustrated in
In the present embodiment, the positive high voltage contact point 205f and the negative high voltage contact point 205g have a structure in which a carbon brush is caulked to a leading end of a metallic plate having elasticity, and the carbon brush comes into contact with the exposed regions 410h and 410i. Since the positive high voltage contact point 205f and the negative high voltage contact point 205g have the elasticity, it is possible to stably supply electric power while following the adsorbing member 410 whose cross-sectional shape changes from hour to hour.
In the adsorbing member 410, a straight line portion 410m and a curved portion 410n are formed along the circumferential direction as illustrated in
Next, a detailed configuration of the adsorbing member 410 and a generation principle of adsorption force by which the adsorbing member 410 adsorbs the sheet S will be described with reference to
Further, in the present embodiment, as will be described later, when the adsorbing member 410 approaches the sheet S, the adsorbing member 410 has appropriate elasticity by adjusting, for example, a material and a thickness of the adsorbing member 410 so that the adsorbing member 410 is bent downward to become a barrel shape. Exposed regions 410d and 410e serving as a conducting portion in which the positive electrode 410a and the negative electrode 410b are exposed are formed on the inner circumferential surface of the adsorbing member 410 that approaches the inner nip conveying roller 501a and the outer nip conveying roller 501b. The high voltage contact point 205f connected with the positive voltage supply unit 205a that applies the positive voltage to the positive electrode 410a via a switch 205c illustrated in
Further, in the present embodiment, the positive voltage of about +1 kV is applied to the positive electrode 410a, and the negative voltage of about −1 kV is applied to the negative electrode 410b. The high voltage contact point 205f and the high voltage contact point 205g have a structure in which a carbon brush is caulked to a leading end of a metallic plate having elasticity, and the carbon brush comes into contact with the exposed regions 410d and 410e of the positive electrode 410a and the negative electrode 410b. Since the high voltage contact point 205f and the high voltage contact point 205g have the elasticity, the high voltage contact point 205f and the high voltage contact point 205g can come into contact with the adsorbing member 410 while following the adsorbing member 410 whose cross-sectional shape changes from hour to hour, and thus electric power can be stably supplied.
Here, as illustrated in (d) of
Next, the sheet feeding operation of the sheet adsorption separation feeding portion 51b according to the present embodiment will be described. (a) of
(b) of
(c) of
(d) of
(e) of
(f) of
The conveyance operation is continuously performed until the rear end of the topmost sheet Sa is detected by the sheet leading end detecting sensor 51c and stopped when the adsorbing member 410 returns to the initial position illustrated in (a) of
In
A zone from the time T3 to a time T4 indicated by (c) is a contact area increase operation zone, and subsequently to the time T1, the conveyance velocity u is set to the velocity U. A zone from the time T4 to a time T5 indicated by (d) is an adsorption operation zone, and at the time T4, the conveyance velocity u is set to 0, the supply voltage vp and the supply voltage vn are set to +V and −V, respectively. A zone from the time T5 to a time T6 indicated by (e) is a separation operation zone, and the conveyance velocity u is set to U at the time T5, and the supply voltage vp and the supply voltage vn are set to +V and −V, respectively, continuously from the time T4.
A zone from the time T6 to a time T10 indicated by (f) is a conveyance operation zone, and the conveyance velocity u is set to U, and the supply voltage vp and the supply voltage vn are set to +V and −V, respectively. At the time T7, the sheet leading end detecting sensor 51c enters the detected state, and since the adsorbing member 410 can convey the sheet S by slightly over two rotations, after the adsorbing member position detecting sensor 206 enters the detected state twice, the sheet leading end detecting sensor 51c enters the non-detected state at the time T8.
Then, when the adsorbing member position detecting sensor 206 enters the detected state at the time T9, all of the conveyance velocity u, the supply voltage vp, and the supply voltage vn are set to 0 at the time T10. The controller 70 determines whether or not the feeding is retried according to whether or not the time T7 falls within a predetermined value range. A zone from the time T10 to a time T11 indicated by (a) is the initial operation, and preparation for feeding of the next sheet S is performed. Thereafter, the above operation is repeated, and thus continuous sheet feeding is performed.
Further, in the present embodiment, the straight line portion 410m of the adsorbing member 410 is formed by adding the reinforcing member 410p to the base layer 410c, but even when the base layer 410c is molded in the shape of the straight line portion 410m and the curved portion 410n, the same effects can be obtained. The straight line portion 410m and the curved portion 410n may be formed of materials that differ in hardness.
Further, in the present embodiment, the electrostatic adsorption force is generated between the adsorbing member 410 and the sheet S through the above configuration, but the present embodiment is not limited to this example. For example, the positive electrode 410a and the negative electrode 410b may not have the comb teeth shape and may have a shape of a uniform electrode in which the electric field can be formed between the electrodes 410a and 410b and the sheet S to dielectric-polarize the sheet S.
The present embodiment has been described in connection with the example in which the adsorbing member 410 includes the straight line portion 410m and the curved portion 410n, but the present invention is not limited to this example. In other words, the present invention may be a configuration in which the adsorbing member 410 includes a first portion and a second portion having a larger curvature than the first portion. Thus, it is possible to adsorb the sheet through the second portion and conveying the sheet upward through the first portion. In order to convey the sheet upward, it is desirable that the first portion have substantially a straight line form.
As described above, in the present embodiment, the adsorbing member 410 is movable to the adsorption position at which the adsorbing member 410 comes into surface contact with the sheet and adsorbs the sheet, the separation position at which the adsorbed sheet is separated from the lower sheet while eliminating the bending, and the separation position at which the adsorbed sheet is separated. Further, the adsorbing member 410 rotates and adsorbs the sheet and hands the adsorbed sheet over to the pair of drawing rollers 51d and 51e, and thereafter, the adsorbing member 410 is stopped at a position (a standby position) away from the sheet.
Further, in the present embodiment, the adsorbing member 410 is configured with the straight line portion 410m and the curved portion 410n. The adsorbing member 410 is moved to the adsorption position at which the curved portion 410n comes into surface contact with the sheet by the rotation of the pair of nip conveying rollers 501, and thereafter, the adsorbing member 410 is pulled up toward the pair of drawing rollers 51d and 51e while eliminating the bending by the straight line portion 410m. As a result, even when the pair of drawing rollers 51d and 51e is arranged above the adsorbing member 410, it is possible to hand the adsorbed sheet over to the pair of drawing rollers 51d and 51e arranged above the adsorbing member 410 when the adsorbing member 410 is rotated. As a result, it is possible to stably perform sheet feeding by the electrostatic adsorption at a low noise with a simple configuration. Further, it is possible to reduce the length of the sheet feeding device in the sheet feeding direction.
Next, a second embodiment of the present invention will be described.
In
The pair of first nip conveying rollers 461 includes a first inner nip conveying roller (a first rotating member) 461a and a first outer nip conveying roller (a first nip member) 461b, and the pair of second nip conveying rollers 462 includes a second inner nip conveying roller (a second rotating member) 462a and a second outer nip conveying roller (a second nip member) 462b. The first inner nip conveying roller 461a is arranged inside the adsorbing member 460 and rotatably shaft-supported by a shaft support member (not illustrated) whose arrangement position is fixed. Driving force is transmitted from the first driving unit 203 to the first inner nip conveying roller 461a through a driving transmission unit (not illustrated).
The first outer nip conveying roller 461b is arranged outside the first inner nip conveying roller 461a with the adsorbing member 460 interposed therebetween and rotatably shaft-supported by a shaft support member (not illustrated) to which a first pressing spring 461c is connected. The first outer nip conveying roller 461b is biased in a shaft center direction of the first inner nip conveying roller 461a by the first pressing spring 461c.
Similarly to the first inner nip conveying roller 461a, the second inner nip conveying roller 462a is arranged inside the adsorbing member 460 and rotatably shaft-supported by a shaft support member (not illustrated) whose arrangement position is fixed. Driving force is transmitted from the second driving unit 204 to the second inner nip conveying roller 462a through a driving transmission unit (not illustrated).
Similarly to the first outer nip conveying roller 461b, the second outer nip conveying roller 462b is arranged outside the second inner nip conveying roller 462a with the adsorbing member 460 interposed therebeteween and rotatably shaft-supported by a shaft support member (not illustrated) to which a second pressing spring 462c is connected. The second outer nip conveying roller 462b is biased in a shaft center direction of the second inner nip conveying roller 462a by the second pressing spring 462c.
The adsorbing member 460 is wound on the pair of first nip conveying rollers 461 and the pair of second nip conveying rollers 462, and has a length larger than the shortest length that can be wound on the pair of first nip conveying rollers 461 and the pair of second nip conveying rollers 462. Since the adsorbing member 460 has this length, there is a gap between the pair of first nip conveying rollers 461 and the pair of second nip conveying rollers 462 and the top surface of the topmost sheet, but the adsorbing member 460 can come into contact with the top surface of the topmost sheet Sa.
The positive voltage supply unit 205a and the negative voltage supply unit 205b are electrically connected to the adsorbing member 460, and the electrostatic adsorption force of attracting the sheet S is generated in the adsorbing member 460 by the voltages applied from the positive and negative voltage supply units 205a and 205b. The switches 205c and 205d that control the voltage supply are connected to the positive high voltage contact point 205f and the negative high voltage contact point 205g, respectively.
In
In the adsorbing member 460, as illustrated in
Further, exposed regions 460h and 460i in which the positive electrode and the negative electrode are exposed are formed on the inner side of the adsorbing member 460, and the protruding portions 460j and 460k are formed on a part of an end surface of the adsorbing member 460. Here, the positive high voltage contact point 205f connected with the positive voltage supply unit illustrated in
Next, the sheet feeding operation of the sheet adsorption separation feeding portion 51b according to the present embodiment will be described. (a) of
(b) of
(c) of
Then, only the second driving unit 204 is continuously driven to increase the contact area Mc. Further, the switches 205c and 205d enter the condition state, and thus since the voltages are applied through the positive voltage supply unit 205a and the negative voltage supply unit 205b of the adsorbing member 460, the electrostatic adsorption force works between the adsorbing member 460 and the topmost sheet Sa.
(d) of
(e) of
As a result, since the pair of first nip conveying rollers 461 nips and conveys the straight line portion 460a of the adsorbing member 460, the topmost sheet Sa adsorbed on the adsorbing member 460 is linearly pulled up as indicated by the arrow A and separated from the loaded next sheet Sb. Further, in the present embodiment, the two straight line portions 460a and 460b are arranged to face each other in the circumferential direction. Thus, when the straight line portion 460a of the adsorbing member 460 is nipped between the pair of first nip conveying rollers 461, the other straight line portion 460b is also nipped between the pair of second nip conveying rollers 462. Accordingly, it is possible to pull up the adsorbing member 460 with certainty.
(f) of
Further, when the leading end of the topmost sheet Sa is conveyed to the downstream further than the nip portion formed by the pair of first nip conveying rollers 461, the leading end of the topmost sheet Sa is peeled off from the adsorbing member 460 through the pair of guides 204a. Thereafter, the peeling of the topmost sheet Sa is increased from the leading end, but the topmost sheet Sa is conveyed by adsorption of the rear end region without change and handed over to the pair of drawing rollers 51d and 51e through detection of the leading end by the sheet leading end detecting sensor 51c. The conveyance operation is continuously performed until the rear end of the topmost sheet Sa is detected by the sheet leading end detecting sensor 51c and stopped when the adsorbing member 460 returns to the initial position illustrated in (a) of
In
In
In
Then, when the first and second adsorbing member position detecting sensors 463 and 464 enter the detected state at the time T10, at the time T11, all of the conveyance velocity u1, the conveyance velocity u2, the supply voltage vp, and the supply voltage vn are set to 0. The controller 70 determines whether or not the feeding is retried according to whether or not the time T8 falls within a predetermined value range. A zone from the time T11 to a time T12 indicated by (a) is the initial operation, and preparation for feeding of the next sheet S is performed. Thereafter, the above operation is repeated, and thus continuous sheet feeding is performed.
As described above, in the present embodiment, the adsorbing member 460 is nipped and conveyed by the pair of first nip conveying rollers 461 and the pair of second nip conveying rollers 462. As described above, by employing the configuration, it is possible to increase the adsorption area between the adsorbing member 460 and the sheet S, and it is possible to obtain solid conveyance force. Further, in the present embodiment, the reinforcing members 460f and 460g are coupled with only the straight line portions 460a and 460b of the base layer (base member) 460e, and thus the magnitude of the stiffness of the straight line portions 460a and 460b is larger than the magnitude of the stiffness of the curved portions 460d and 460c. However, the present embodiment is not limited to this example, and the straight line portions 460a and 460b of the adsorbing member 460 may be configured with any other member having the stiffness larger than that of the curved portions 460d and 460c.
Next, a third embodiment of the present invention will be described.
In
In parallel with the conveyance operation of the adsorbing member 470, an alternating voltage is applied from the charging roller 250a pressed on the surface of the adsorbing member 470. As a result, a region charged to a positive polarity and a region charged to a negative polarity are formed on the surface of the adsorbing member 470 in a stripe form at intervals corresponding to the frequency of the AC power source 252 and the surface moving velocity of the adsorbing member 470 as illustrated in (a) and (b) of
As described above, in the present embodiment, it is possible to obtain the sheet adsorption force by charging the surface layer of the adsorbing member from the outside by the charging roller 250a. As a result, since it is possible to charge the adsorbing member 470 without the electrode arranged inside the adsorbing member, it is possible to simplify the configuration of the adsorbing member 470 and reduce the cost.
In the embodiment described so far, the sheet S is adsorbed on the adsorbing member by the electrostatic adsorption force, but the present invention is not limited to this example. For example, a fine fiber structure of a submicron order may be formed on the adsorbing member, and the sheet S may adsorbed by intermolecular attractive force working between the sheet S and the fine fiber structure.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2013-083584 | Apr 2013 | JP | national |
| 2014-056025 | Mar 2014 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2014/060411 | 4/10/2014 | WO | 00 |
