JP4834533B2 - Sheet conveying apparatus and image forming apparatus provided with the same - Google Patents

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, a facsimile machine, a printer, and a multifunction machine (multifunctional copying machine) using an electrophotographic system or an ink jet recording system, and is equipped with the image forming apparatus and a sheet such as recording paper. The present invention relates to a sheet conveying apparatus that conveys a sheet.

  A sheet conveying apparatus that conveys paper sheets, such as an ATM apparatus that handles cash such as banknotes, is widely used. Usually, such a sheet conveying apparatus is provided with a motor as a conveyance driving source, and a power transmission device that appropriately decelerates and transmits rotational power output from the driving motor.

  In the case of an image forming apparatus, a sheet conveying device provided in the image forming apparatus is provided with a member such as an endless conveying belt and a conveying roller in addition to a main mechanism using a drive motor and a power transmission device. For this reason, the existence of such members as belts and rollers has been an obstacle to downsizing of the sheet conveying apparatus, and hence downsizing of the main body of the image forming apparatus. On the other hand, particularly in the sheet conveying device of the image forming apparatus, when a sheet is jammed during conveyance, it is necessary to quickly cope with the jam processing. In view of this, a sheet conveying apparatus that employs a pre-transfer electrode that does not use a belt or a roller has been proposed as a device that can be downsized and that can provide stable conveying performance. The pre-transfer electrode has a simplified device and uses electrostatic attraction and repulsion, so jamming is less likely to occur. There are two known sheet conveying apparatuses using the pre-transfer electrode, an indirect sheet conveying system and a direct sheet conveying system.

  In the former indirect sheet conveying method, a sheet is conveyed by driving the dielectric belt with a pre-transfer electrode in a state where a sheet as a material to be conveyed is adsorbed to the dielectric belt. (For example, refer to Patent Document 1).

  In addition, a sheet conveying apparatus is proposed in which a voltage is applied to the sheet conveying guide to function as a pre-transfer electrode, the sheet on the conveying roller is pressed by a pressing roller from above, and the sheet is conveyed with a mechanical rotational frictional force. (For example, refer to Patent Document 2). In this case, the sheet conveying guide has a plurality of strip electrodes arranged in the longitudinal direction, and acts as a stator formed of an insulator. The transport roller functions as a mover formed by laminating a resistor layer on an insulator layer.

  There has also been proposed a pre-transfer electrode in which a sheet is placed on a moving element via a spacer made of an insulating film and conveyed in that state (see, for example, Patent Document 3). In this case, the sheet conveyance guide in which the strip electrodes are arranged is made to act as a stator, and a movable element provided with a resistor layer on an insulating thin leaf is brought into contact with the sheet conveyance guide.

  On the other hand, as for the latter direct sheet conveying system, there are an image forming apparatus and a sheet conveying apparatus that combine the drive motor and the pre-transfer electrode previously proposed by the present applicant so that the operation can be switched (for example, Patent Documents). 4). Since the pre-transfer electrode uses electrostatic force, it cannot be used in the electrophotographic process using electrostatic force, particularly in the transfer region. Therefore, in the transfer region, the pre-transfer electrode is switched to the operation of the drive motor.

  In addition, because of the high humidity, the electrical resistance between the sheet and the grounding surface such as the electrode becomes low, and if the charge on the sheet leaks a lot and the driving coulomb force decreases, the sheet conveyance speed decreases. In order to solve this problem, the present applicant has proposed (for example, see Patent Document 5). That is, when the sheet conveyance speed is lowered due to a decrease in the driving coulomb force, appropriate process conditions around the photosensitive drum, which is an image carrier, are set in accordance with fluctuations in the conveyance speed. For example, the control is performed by at least one control means of a light quantity control means, a charging voltage control means, a developing bias control means, a transfer voltage control means, and a separation voltage control means. As a result, the image quality is prevented from deteriorating due to fluctuations in the sheet conveying speed.

Japanese Patent Laid-Open No. 7-17654 JP-A-6-298393 Japanese Patent No. 2632452 JP-A-8-73067 JP-A-8-166694

  By the way, as the indirect sheet conveying system, as can be seen from the above-mentioned patent documents, a system that conveys a sheet with a mechanical frictional rotational force by a belt or a roller, and a system that conveys a sheet with a moving element interposed therebetween. Can be divided into two categories. In the method of conveying by the frictional rotational force, not only the belt and the roller but also the member that supports both of these members is necessary and cannot be omitted. Therefore, it is difficult to downsize the sheet conveying apparatus. In addition, in the case of a method of conveying with a moving element, a large number of moving elements are required according to the number of sheets to be conveyed. In other words, the sheets are placed on the movable element in advance before being conveyed, but particularly when a large number of sheets are conveyed in a large number of print jobs, the process of placing on the movable element is difficult and requires a processing device therefor. . In addition, it is necessary to provide a process and an accompanying device for peeling the sheet after conveyance from the moving element. Therefore, there is a problem that the structure of the sheet conveying apparatus becomes very complicated.

  On the other hand, the direct sheet conveying method also has the following problems. In the structure in which the drive motor and the electrostatic actuator are combined so that the operation can be switched, it is difficult to reduce the size by using the conventional drive motor. Further, in this case, the sheet is in a moisture absorption state in a high humidity environment, and the sheet conveyance speed is controlled depending on the cron force of the electrostatic action that changes accordingly. Therefore, since the print job time is delayed in a high humidity environment or in a sheet wet state, as a sheet conveying apparatus employed in a large high-speed image forming apparatus that handles a large number of sheets in a large number of print jobs that require processing as short as possible, It is disadvantageous.

  As described above, regardless of the indirect / direct sheet conveyance system, the apparatus is complicated and there are many problems that are difficult to achieve in miniaturization. Further, the problem that the sheet transport time is affected when the sheet becomes wet cannot be a fundamental solution. Above all, the problem that the electrostatic actuator cannot be used in the transfer area of the electrophotographic process must be overcome.

  SUMMARY OF THE INVENTION An object of the present invention is an electrostatic force actuator type sheet conveying apparatus that uses an electrostatic force as a sheet conveying force, which realizes simplification and miniaturization of the apparatus, and can also be used in a transfer area of an electrophotographic process. Is to make it.

In order to achieve the above object, a sheet conveying apparatus according to the present invention conveys a sheet fed from a sheet feeding unit to an electrophotographic process means, and transfers a toner image formed by the electrophotographic process means in a transfer process area. In the sheet conveying apparatus that further conveys the sheet toward the fixing unit, the sheet conveying guide of the insulator that forms the sheet conveying path, and the upstream of the transfer process area in the sheet conveying guide in the sheet conveying direction. A pre-transfer electrode formed by a plurality of strip-shaped electrodes provided on the side and extending in a strip shape at a predetermined pitch along the sheet conveyance direction, and a control unit capable of adjusting a voltage applied to the pre-transfer electrode. And the controller moves the sheet in the sheet conveyance direction by an electrostatic force generated by applying a voltage to the pre-transfer electrode, and a toner electrode is applied to the pre-transfer electrode. Wherein the moving to the same polarity as the voltage zero or toner polarity charge amount of the sheet by applying the comprising opposite polarity so as to charge elimination by a sheet the transfer process area.

  According to the sheet conveying apparatus of the present invention, the driving mechanism that moves and conveys the sheet is mainly composed of a sheet conveying guide that functions as a pre-transfer electrode. Therefore, the conventional driving motor, power transmission mechanism, conveying belt, The conveyance roller and the shaft support member can be omitted. Therefore, the number of parts of the entire sheet conveying apparatus is greatly reduced, and the size can be simplified and downsized. In addition, the problem that the sheet conveyance speed becomes slow due to the sheet becoming wet in a high humidity environment is solved, and the sheet conveyance guide functions as a pre-transfer electrode using electrostatic force even in the transfer region of the electrophotographic process means. There are advantages that can be made.

  Hereinafter, embodiments of a sheet conveying apparatus according to the present invention and an image forming apparatus equipped with the sheet conveying apparatus will be described in detail with reference to the drawings.

(Image forming device)
FIG. 1 is a functional block diagram of the configuration showing an example of an image forming apparatus. The apparatus main body is roughly divided into a document reading unit 1, a photosensitive drum 2, a pre-exposure unit (irradiation device) 3, a charger 4, a developing unit (developing unit) 6, a control unit 7, and the like. Yes.

  The document reading unit 1 reads an image of the document and outputs it as an optical image. This optical image is visualized by electrophotographic process means comprising the following devices. A photosensitive drum 2 is provided as an image carrier, and a latent image is formed by an optical image from the document reading unit 1. The pre-exposure unit 3 erases the latent image image in front of the photosensitive drum 2. The charger 4 applies a charging bias voltage to the photosensitive drum 2 to uniformly charge the drum surface. The developing unit 6 develops toner on the latent image on the photosensitive drum 2. The controller 7 controls the overall operation of the system of the image forming apparatus main body including the above devices. Therefore, the control unit 7 functions as a light amount control unit, a charging voltage control unit, a developing bias control unit, a transfer voltage control unit, a separation voltage control unit, a sheet position measurement unit, and an electrostatic actuator application voltage control unit.

  Further, the apparatus main body is provided with a paper feed cassette 8 for storing sheets in preparation for the start of paper feed, and has a paper feed separation roller 9 for feeding the sheets from the paper feed cassette 8 to a transport unit.

In addition, a sheet conveyance guide 10 that forms a conveyance path is provided as a main part of a sheet conveyance apparatus described later. The sheet conveyance guide 10 has a long length for conveying the sheet from the sheet feeding separation roller 9 to the fixing device 13, and the lower passage wall 11 and the upper passage walls 31 and 32 are formed using an insulating material. . To generate electrostatic force by applying a voltage to such sheet conveying guide 10, function as an "electrodes" is a gist of the present embodiment.

More specifically, as shown in FIG. 1, a full length section from the paper feed separation roller 9 to the photosensitive drum 2 is formed by a lower passage wall 11 and upper passage walls 31, 32, and this full length section is defined as a full length section. function as electrodes portion. In its length section, a section from the paper separation roller 9 to the photosensitive drum 2 is made to function as a transcription front electrode portions are formed in the lower passage wall 11 and the upper passage wall 31. Further, the portion where the upper passage wall is interrupted facing the photosensitive drum 2 is constituted only by the lower passage wall 11, and the passage wall portion serves as a transfer separation portion 11 a. A portion formed by the lower passage wall 11 and the upper passage wall 32 in the section downstream from the transfer separation portion 11a functions as a downstream electrode portion.

In the downstream electrode section only of the transfer separation section 11a, the toner image on the photosensitive drum 2 is transferred to the conveyed sheet, and the sheet is peeled off from the surface of the photosensitive drum 2. As shown in FIG. 3 and subsequent figures, in the transfer separation unit 11a forming the downstream electrode unit, the transfer electrode 42 for applying a transfer voltage and the separation for applying a separation voltage for peeling the sheet from the photosensitive drum 2 are used. An electrode 43 is provided.

The sheet having the toner image transferred is then advanced further movement to the downstream side by features Kiten shooting front electrode portion after being formed by the lower passage wall 11 and the upper passage wall 32, sent to the fixing unit 13 Toner The image is permanently fixed by heating and pressing. The sheet after fixing is discharged from the fixing device 13 and is received and collected by the discharge tray 13.

In Figure 1, the Do that metal contacts from three sections (pre-transfer electrode unit, the transfer and separation device, downstream electrode portion), such as a voltage applied by the actuation off signal from the drive unit 15,12,17 respectively corresponding To be driven. The drum driving unit 16 drives the photosensitive drum 2 to rotate at a constant speed. The fixing device driving unit 18 operates the fixing device 13. In addition, a surface potential sensor 20 that measures the surface potential of the sheet being conveyed is disposed, and sheet detection sensors 21 to 24 that monitor and detect the movement of the sheet being conveyed are also required throughout the entire length of the sheet conveyance guide 10. Has been placed.

Lower passage wall 11 and the upper passage wall 31, 32 of the conveying guide 10 functioning as electrodes portion, as shown in each of FIGS. 2 (a) and FIG. 3 below, the conveyance direction on the surface of the opposed inner surfaces ( It is composed of an insulator in which electrodes are arranged in a strip shape at a predetermined pitch along the sheet conveyance direction .

For convenience of description, the sheet conveying guide 10 constituted by the lower through-wall 11 and the upper through-walls 31 and 32 made of this insulator will be referred to as “stator 10” of the above-described three sections of electrodes for convenience of description. There is a case. Accordingly, the voltages V1, V2, and V3 are applied to the stator 10 in a state where the sheet is placed on the stator 10. For example, as shown in FIG. 2A, the voltage V1 is set to +1000 volts, the voltage V2 is set to -1000 volts, and the voltage V3 is set to 0 volts.

  With the above configuration, the image forming apparatus of this embodiment operates as follows.

The surface of the photosensitive drum 2 is neutralized by pre-exposure by the pre-exposure unit 3, and is uniformly charged by the charger 4, and the light image from the document reading unit 1 is irradiated to form a latent image. On the surface of the photosensitive drum 2 on which the latent image is formed, the toner adheres to the latent image on the surface of the photosensitive drum 2 by the developing unit 6 to form a toner image. At that time, the sheet is fed from the sheet feeding cassette 8 by the sheet feeding separation roller 9 and conveyed to the photosensitive drum 2 through the passage wall 31 in the first and second sections. When the sheet is sent to the vicinity of the transfer separation region 11, the surface potential of the sheet is measured by the surface potential sensor 20, and the stator 10 is set so that the surface potential of the sheet becomes “zero or reverse polarity of toner polarity”. A voltage is applied to the upper electrode. In the transfer separation unit 11, a transfer voltage is applied to the transfer electrode of the stator 10 facing the photosensitive drum 2, and the toner image on the surface of the photosensitive drum 2 is transferred onto the sheet. A separation voltage is applied to the next electrode after the transfer electrode, and the sheet is peeled off from the photosensitive drum 2. The sheet on which the toner image is placed is sent to a fixing device 13 by a sheet conveyance guide 10 that forms electrode sections in three sections, and the image is permanently fixed. After fixing, the sheet is discharged to a discharge tray 14 and the print job is completed. To do.

(Sheet Conveying Device: First Embodiment)
Next, with reference to FIG. 1 and FIGS. 2A to 2E, the configuration and the sheet conveying operation in the electrode section in the three sections will be described.

  When the sheet reaches the sheet conveyance guide 10 that functions as the stator 10 of the pre-transfer electrode, voltages V1, V2, and V3 are applied to the stator 10. When a voltage is applied to each electrode on the stator 10, the charge moves within the sheet, and the positive (+) electrode and the negative (−) electrode are charged in a band shape. When in an equilibrium state, FIG. 2 (b) shows a virtualized charge in the sheet. Further, as shown in FIG. 2C, when the voltage applied to the electrode of the stator 10 is changed, the charge of the electrode of the stator 10 is instantaneously switched, but the charge on the sheet is hindered by the resistance for a while. Stay in place. That is, in the relationship between the lower through-wall 11 that is the stator 10 and the sheet, the repulsive force in the direction perpendicular to the sheet is caused by the action between the electrode of the stator 10 and the charge that appears in the sheet due to the remaining charge. Propulsion in the right direction is generated. As a result, as shown in FIG. 2D, the sheet moves forward a distance corresponding to one pitch of the electrodes. The seat moves forward by repeatedly receiving such driving force. Similarly, in the relationship between the upper passages 31 and 32, which are also the stator 10, and the sheet, if the steps of charging and moving the sheet are repeated in the same manner, it is converted into a continuous forward movement of the sheet as the mover. Is done.

  In summary, the sheet conveyance guide 10 functions as a stator of the pre-transfer electrode, charges electric charges on the conveyed sheet as a mover, and moves the charge pattern on the stator side. An electrostatic force is generated between the voltage on the stator side and the electric charge charged on the mover sheet, and the electrostatic force is applied to the sheet of the mover as a driving coulomb force for movement.

  In general, if the surface resistivity of the mover is too low, the charge charged on the mover disappears before the mover moves one step, and sufficient driving cannot be performed. On the contrary, if the surface resistivity is too high, it takes a long time to charge the charge on the moving element, and it is impossible to drive quickly.

  Also in this regard, according to the present embodiment, since the sheet conveyance guide 10 is provided in which the lower passage wall 11 and the upper passage walls 31 and 32 are opposed to each other in the vertical direction, the sheet conveyance guide 10 functions effectively as a pre-transfer electrode. Power up and charge charge time can be shortened. Further, even when the sheet has a variation in surface resistivity due to the influence of humidity, a stable driving Coulomb force can be obtained. If necessary, the charge polarity pattern applied to the opposed stator is changed, that is, the opposite polarity or the phase of the arrangement electrode is shifted according to the environment and the material of the sheet. This makes it possible to obtain a more stable driving force by setting the same polarity as the sheet charge and pressing the sheet against one of the opposing stators, or by setting the one-step moving distance short.

  3 to 6 show in detail the configuration of the process of transferring the toner image from the photosensitive drum 2 to the sheet and separating the sheet in the electrophotographic process means centering on the photosensitive drum 2. FIG.

  As shown in FIG. 3, in the transfer separation unit 11 a (see FIG. 1) of the sheet conveyance guide 10 facing the photosensitive drum 2, the upper side wall is interrupted, and the conveyance surface of the lower side wall 11 of the sheet conveyance guide 10 is broken. An electrode 41 is provided. The controller 7 applies a static elimination voltage to the electrode 41 so that the surface potential of the sheet becomes “zero or reverse polarity of toner polarity” while detecting the charge on the sheet by the surface potential sensor (potential measuring means) 20. To control. That is, based on the charge on the sheet detected by the surface potential sensor 20, the control unit 7 applies a static elimination voltage to the electrode 41 so that the charge state on the sheet does not hinder the transfer of the toner image. This adjusts the charge amount of the sheet. The transfer electrode 42 is also provided on the lower through wall 11 of the sheet conveyance guide 10. The control unit 7 controls the transfer electrode 42 to apply a transfer voltage having a polarity opposite to that of the toner, and attracts and attracts the toner to the sheet. That is, at the image transfer timing for the sheet to reach the photosensitive drum 2 and transfer the toner on the photosensitive drum 2, the controller 7 applies a transfer voltage having a polarity opposite to that of the toner. As a result, the toner is attracted to the sheet, and the toner moves on the sheet. The separation electrode 43 is also provided on the lower through wall 11 of the sheet conveyance guide 10. The controller 7 controls the separation electrode 43 to apply a separation voltage that enables electrostatic separation. As a result, the sheet moves on the sheet conveyance guide 10 without being attracted to the photosensitive drum 2.

4 to 6, the transfer area from the photosensitive drum 2 to the sheet and the area where the sheet is separated from the photosensitive drum 2 are before fixing, and the toner on which the image is formed is electrostatically adhered onto the sheet. It ’s just that. Therefore, in order to convey the sheet without scattering only the adhered toner, the toner is electrostatically adsorbed and held. As shown in FIG. 4, in the transfer region where the transfer of the toner image from the photosensitive drum 2 to the sheet is started, the charge (+) having the same polarity as the charge (+) of the sheet is transferred to the transfer electrode 42 on the lower side wall 11. Is applied as a transfer voltage. As shown in FIG. 5, a separation voltage is applied to the separation electrode 43 of the lower through-wall 11 this time in order to separate the leading portion of the sheet after the transfer from the photosensitive drum 2. A drive charge is applied to the electrode where the leading portion of the sheet where the toner image is not placed has reached. The passage of the leading edge of the sheet is detected by the sheet detection sensor 23 (see FIG. 6). Only the charge having the same polarity as the toner is applied to the electrode of the sheet on which the toner image is formed and mounted. The sheet that has entered between the lower side wall 11 and the upper side wall 32 is conveyed to the fixing device 13 with the downstream electrode portion functioning.

  The operations and effects of the sheet conveying apparatus of the present embodiment will be listed below from the above configuration.

  (1) The sheet is conveyed while being moved in the forward direction by the sheet conveyance guide 10 functioning as a pre-transfer electrode, and the toner image is transferred from the photosensitive drum 2 in the transfer separation unit 11a during that time. The photosensitive drum 2 is peeled off.

  (2) As seen in a conventional sheet conveying device using mechanical rotational frictional force, the sheet is transferred by contacting the belt, the roller, the guide member, and the peripheral surface of the photosensitive drum each time. On the other hand, such seats will not be exchanged. For this reason, there is no defect in the transferred image due to a shock at the time of entering the sheet or a displacement of the contact position, so that good image quality can be obtained.

  (3) In the sheet conveyance region (upper passage walls 31 and 32) of the sheet conveyance guide 10, since the pre-transfer electrode action is expected on both the front and back surfaces of the sheet, the driving force for conveying the sheet is increased. Charge charging time is also shortened. Even when the sheet is in a wet state including humidity and affected by the surface resistivity, a stable sheet conveyance driving force can be obtained.

  (4) Similarly, in the sheet conveyance area of the sheet conveyance guide 10, the same polarity as the sheet charge can be obtained by arranging the striped electrode pitches alternately on the opposing upper and lower walls 31, 32 and lower wall 11. Thus, the sheet is pressed against the opposing wall. By this function, the moving distance for one step can be set short, and a more stable driving force can be obtained, which is not affected by the environment or the sheet material.

  The embodiments of the sheet conveying apparatus and the image forming apparatus of the present invention have been described above, but the present invention is not limited to these embodiments, and other embodiments and applications are within the scope of the present invention. Examples, variations, and combinations thereof are possible.

1 is a functional block diagram illustrating an image forming apparatus equipped with a sheet conveying apparatus according to an embodiment of the present invention. FIGS. 9A to 9E are operation diagrams in which the sheet conveyance guide functions as a pre-transfer electrode to move the sheet forward. The figure which shows the flow of the sheet | seat in the process part of transcription | transfer and separation in this embodiment. The figure which similarly shows the flow of the sheet | seat in the process part of transcription | transfer and separation of this embodiment. The figure which similarly shows the flow of the sheet | seat in the process part of transcription | transfer and separation of this embodiment. FIG. 6 is a view showing a sheet flow in a conveyance process portion from the transfer and separation region to the fixing device according to the present embodiment.

2 Photosensitive drum (image carrier)
7 Control unit 10 Sheet conveyance guide (functions as “pre-transfer electrode”)
12, 15, 17 Actuator driving unit 13 Fixing device 20 Surface potential sensor (potential measuring means)
11 Lower wall (sheet conveyance guide)
11a Transfer separation unit 31, 32 Upper wall (sheet conveyance guide)
41 Strip electrode 42 Transfer electrode 43 Separation electrode

Claims (6)

A sheet that is fed from a sheet feeding unit to an electrophotographic process unit, and a toner image formed by the electrophotographic process unit is transferred to a sheet in a transfer process area, and then the sheet is conveyed toward a fixing unit. In the transport device,
An insulating sheet conveying guide that forms a sheet conveying path ;
A pre-transfer electrode that is provided upstream of the transfer process region in the sheet transport guide in the sheet transport direction and formed by a plurality of strip electrodes extending in a strip shape at a predetermined pitch along the sheet transport direction;
A control unit capable of adjusting a voltage applied to the pre-transfer electrode,
The controller is
Move the sheet in the sheet conveyance direction with an electrostatic force generated by applying a voltage to the pre-transfer electrode,
A voltage having the same polarity as the toner polarity is applied to the pre-transfer electrode to remove the charge so that the charge amount of the sheet is zero or opposite to the polarity of the toner, and the sheet is moved to the transfer process region. Sheet transport device. Having a potential measuring means for detecting the surface potential value of the sheet;
The sheet conveying apparatus according to claim 1, wherein a voltage based on the potential measured by the potential measuring unit is applied to the pre-transfer electrode. The sheet conveyance guide is located downstream of the pre-transfer electrode in the sheet conveyance direction,
A transfer electrode that applies a voltage with a polarity opposite to that of the toner in order to transfer the toner image formed on the electrophotographic process means to the sheet whose charge amount is adjusted by the pre-transfer electrode ;
A separation electrode for applying a voltage with the same polarity as the toner polarity in order to separate the sheet on which the toner has been transferred by the transfer electrode from the electrophotographic process means;
The sheet conveying apparatus according to claim 1 , further comprising: In moving the sheet in the sheet conveying direction by the electrostatic force generated by applying a voltage to the pre-transfer electrode by the control unit,
The plurality of strip electrodes charge a charge on the conveyed sheet,
The control unit moves the charge patterns of the plurality of strip electrodes in response to an operation on / off signal from the driving unit,
4. The sheet conveying apparatus according to claim 1, wherein the sheet moves in the sheet conveying direction by an electrostatic force generated between the voltages of the plurality of strip electrodes and the charge of the sheet. 5. . The sheet conveying guide has an upper side wall and a lower side wall facing each other in the vertical direction,
The upper passage wall is disposed upstream of the transfer process region in the sheet conveying direction and has the pre-transfer electrode therein.
The lower through wall is disposed from the upstream side of the transfer process region to the downstream side of the transfer process region in the sheet conveying direction, and has the pre-transfer electrode, the transfer electrode, and the separation electrode inside. And
A portion for removing the charge so that the charge amount of the sheet is zero or opposite to the toner polarity by applying a voltage having the same polarity as the toner polarity in the pre-transfer electrode is disposed on the process area side of the pre-transfer electrode. sheet conveying apparatus according to claim 3, characterized in that it is.   A sheet conveying device according to any one of claims 1 to 5, wherein the toner image formed by the electrophotographic process means is transferred to the sheet conveyed by the sheet conveying device, and the transferred sheet is transferred. Further, an image forming apparatus, wherein the sheet is conveyed to a fixing unit by the sheet conveying device to perform a fixing process.

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