JP2004045530A - Transfer device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the deterioration of transfer performance due to paper powder generated from a form paper. <P>SOLUTION: When a prescribed time(for example, 100msec.) passes after the end of a last paper passing period A, voltage is applied on a charge wire for only 50msec., thereafter, voltage is applied on the charge wire again for only 50msec. with leaving a time interval of 50msec., the on/off of applying the voltage on the charge wire are repeated several times(for example, five times) before the start of the following paper passing period A. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a transfer device provided in an image forming apparatus such as a copying machine, a printer, a facsimile, and the like, for transferring a toner image formed on the surface of a photoreceptor to a sheet.
[0002]
[Prior art]
In an image forming apparatus, a toner image is formed on a surface of a photoreceptor provided in an image forming unit, and the toner image is transferred to a sheet, whereby an image can be formed on a sheet. There is something. In this type of image forming apparatus, the surface of the photoreceptor is uniformly charged by, for example, a discharge of a main charger, and is then exposed to light emitted from an exposure device. As a result, a so-called electrostatic latent image is formed on the surface of the photoconductor. The developing device attaches toner to the surface of the photoconductor on which the electrostatic latent image is formed, and a toner image is formed.
[0003]
The toner image formed on the photoreceptor surface is transferred to a sheet by the operation of a transfer device arranged to face the photoreceptor surface, for example. The toner on the surface of the photoconductor is, for example, charged to a positive potential. The transfer device includes, for example, a charge wire that can be energized, so that the charge wire has a negative potential (potential opposite to that of the toner) when a sheet passes between the photoconductor and the transfer device (transfer position). , The toner on the surface of the photoreceptor is electrostatically attracted (sucked) to the transfer device side, and the toner image can be transferred to the paper.
[0004]
[Problems to be solved by the invention]
Paper used for image formation usually contains a filler such as talc. The filler contained in the paper is separated from the paper by rubbing or the like in the process of transporting the paper, and is scattered as so-called paper dust in the image forming apparatus. In particular, when paper is jammed in the image forming apparatus (so-called JAM), a large amount of paper dust is generated when the jammed paper is removed.
[0005]
When the scattered paper dust is placed on the charge wire, when a voltage is applied to the charge wire during transfer, the toner suction force at the portion where the paper dust is placed is reduced, and the toner on the surface of the photoreceptor facing the portion is removed. It may not be transferred to paper.
In addition, since the leading and trailing edges of the paper are cut surfaces, paper dust is likely to be generated. For this reason, when the leading end and the trailing end of the paper pass through the transfer position, a large amount of paper dust may fall on the charge wire. In particular, after the trailing edge of the sheet has passed the transfer position, no voltage is applied to the charge wire until the succeeding sheet has passed the transfer position. Pass through the transfer position, and the above-mentioned adverse effects are large.
[0006]
The present invention has been made under such a background, and an object of the present invention is to provide a transfer device that can prevent the transfer performance from being reduced due to paper dust generated from paper.
[0007]
Means for Solving the Problems and Effects of the Invention
According to the first aspect of the present invention, the charged toner adhering to the surface of the photoreceptor (2) is electrostatically attracted to the sheet (P) at the transfer position (S). A transfer device (6) for an image forming apparatus for transferring a toner, wherein the charge wire (61) is disposed opposite to the surface of the photoreceptor, and has a potential opposite to that of the toner. Application means (11) for electrostatically attracting the toner on the photoreceptor surface to the transfer device side by applying a voltage to the charge wire as described above, and the application means sets the transfer position. A transfer device characterized in that a predetermined voltage can be applied to the charge wire even when a sheet is not passing (time interval B).
[0008]
It should be noted that the alphanumeric characters in parentheses indicate corresponding components and the like in embodiments described later. Hereinafter, the same applies in this section.
For example, the toner on the surface of the photoreceptor is charged to a positive potential, and at the time of transfer, a negative potential is applied to the charge wire, so that the toner is electrostatically attracted to the charge wire side. On the other hand, most of the paper dust generated from paper used for image formation is usually charged to a negative potential.
[0009]
According to the configuration of the present invention, when the paper does not pass through the transfer position, by applying a voltage so that the charge wire has a negative potential, the negatively charged paper powder placed on the charge wire is applied. And an electrostatic repulsion can be generated. Thereby, the paper dust charged to the negative potential can be removed from the charge wire. Therefore, it is possible to prevent the transfer performance from being reduced due to the paper dust generated from the paper.
[0010]
According to a second aspect of the present invention, in the case where transfer is continuously performed on a plurality of sheets of paper (P), the application unit (11) is configured such that after the transfer to the preceding sheet is completed, the subsequent sheet is not transferred. 2. The transfer apparatus according to claim 1, wherein on / off of application of a voltage to the charge wire is repeated a plurality of times until the transfer position reaches the transfer position. 3.
According to this configuration, the charge wire can be vibrated by repeatedly turning on / off the application of the voltage to the charge wire a plurality of times, so that the paper dust can be more effectively removed.
[0011]
Most of the paper dust generated from the paper is charged to a negative potential, but the toner charged to the positive potential may be charged to the positive potential or may not be charged any more due to the attachment of the toner charged to the positive potential.
According to the configuration of the present invention, by turning on / off the application of the voltage to the charge wire a plurality of times and vibrating the charge wire, the paper dust charged to a positive potential and the paper dust not charged are also effective. Can be removed.
[0012]
According to a third aspect of the present invention, when the processing for removing the jammed sheet in the image forming apparatus is performed, the application unit (11) shifts the subsequently sent sheet (P) to the transfer position (S). 3. The transfer device according to claim 1, wherein a voltage is applied to the charge wire (61) before the transfer reaches (1).
According to this configuration, the paper dust generated when the jammed paper is removed in the image forming apparatus can be removed from the charge wire until the subsequently fed paper reaches the transfer position. .
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings.
FIG. 1 is a schematic diagram illustrating a configuration of an image forming unit 1 of an image forming apparatus according to an embodiment of the present disclosure.
The image forming apparatus according to the present embodiment is, for example, a copying machine, in which a toner image corresponding to an image of a document read by a document reading unit (not shown) is created and transferred to a sheet P. Image forming section 1 is arranged. The image forming unit 1 includes a photoreceptor 2, a main charger 3, an exposure device 4, a developing device 5, a transfer device 6, and a cleaning device 7, and forms an image by, for example, a so-called reversal developing method.
[0014]
The photoconductor 2 is, for example, a cylindrical body extending in the front-rear direction in FIG. 1 and is driven to rotate clockwise. During image formation, first, the surface of the photoconductor 2 is uniformly charged to a positive potential by the discharge of the main charger 3.
The surface of the photoconductor 2 charged by the main charger 3 is selectively irradiated with light from the exposure device 4 in correspondence with an image to be formed on the paper P (an image of a document read by a document reading unit). Exposed. As a result, a so-called electrostatic latent image is formed on the surface of the photoreceptor 2, which is composed of a region charged to a positive potential by the main charger 3 and a region charged to a low positive potential due to exposure. . Then, on the surface of the photoreceptor 2 on which the electrostatic latent image is formed, toner is adhered by the developing device 5 to the region where the potential has become low, whereby the electrostatic latent image is developed and the toner image is formed. Become. The toner attached to the surface of the photoconductor 2 is charged to a positive potential.
[0015]
The paper P used for image formation is stored in a paper storage unit (not shown), and is sent from the paper storage unit to the image forming unit 1 through the paper conveyance path 8. A registration roller 9 for sending out the sent paper P toward the image forming unit 1 at a predetermined timing is disposed at the end of the paper transport path 8. The sheet P sent from the sheet storage unit and conveyed through the sheet conveying path 8 is temporarily stopped when the leading end thereof reaches the registration roller 9. The timing at which the toner image formed on the surface of the photoreceptor 2 comes to a position facing the transfer device 6 and the timing at which the sheet arrives at the transfer position S (between the photoreceptor 2 and the transfer device 6) match. Thus, the rotation of the registration roller 9 is started, and the sheet P is sent to the transfer position S over the guide 10.
[0016]
The transfer device 6 includes, for example, two energizable charge wires 61. The charge wire 61 is electrically connected to a control unit 11 provided in the image forming apparatus, and controls on / off of application of a voltage to the charge wire 61 based on an output signal from the control unit 11. I can do it. While the paper P passes through the transfer position S (paper passing period), a negative potential (potential opposite to the charged potential of the toner) is applied to the charge wire 61 to electrostatically transfer the toner on the surface of the photoconductor 2 to the transfer device 6. The toner image can be transferred to the sheet P by being attracted (sucked) to the side.
[0017]
The sheet on which the toner image has been transferred is guided to a fixing device (not shown), and after being subjected to a fixing process by the fixing device, is discharged out of the image forming apparatus.
The toner remaining on the surface of the photoreceptor after the transfer of the toner image is collected by a cleaning device.
FIG. 2 is a time chart showing an example of on / off control of application of a voltage to the charge wire 61.
[0018]
In the image forming apparatus according to the present embodiment, when the image to be formed on the paper P is a plurality of papers, the plurality of papers P are automatically sent out sequentially from the paper storage unit, and a predetermined time interval B (for example, 660 msec), and transfer can be continuously performed. That is, when an image is formed on a plurality of sheets P, a sheet passing period A and a time interval B during which the sheet does not pass through the transfer position S appear alternately as shown in FIG. For example, when a sheet P of A4 size (A, No. 4 in Japanese Industrial Standard (JIS)) is fed along the short side direction (lateral direction), the sheet passing period A is 840 msec.
[0019]
During the paper passing period A, the voltage is applied (turned on) to the charge wire 61. Thus, as described above, the toner on the surface of the photoconductor 2 is electrostatically attracted to the charge wire 61 side, and the toner image can be transferred to the paper P.
The feature of this embodiment is that a voltage is applied to the charge wire 61 during the time interval B during which the sheet P does not pass through the transfer position S (until the subsequent sheet P reaches the transfer position S). The point is to be. Specifically, after a lapse of a predetermined time (for example, 100 msec) after the end of the immediately preceding paper passing period A, the application of the voltage to the charge wire 61 is turned on for, for example, 50 msec. By turning on the voltage application to the charge wire 61, the on / off of the voltage application to the charge wire 61 is repeated a plurality of times (for example, five times) until the next sheet passing period A starts. It has become.
[0020]
Paper P used for image formation usually contains a filler such as talc.
The filler contained in the paper P is separated from the paper P by rubbing or the like in the process of transporting the paper P, and is scattered as so-called paper dust in the image forming apparatus. Usually, most of the paper dust is charged to a negative potential. When the scattered paper dust is placed on the charge wire 61, when a voltage is applied to the charge wire 61 at the time of transfer, the toner suction force at the portion where the paper dust is placed is reduced, and the photoconductor 2 facing the portion is reduced. The toner on the surface may not be transferred to the paper P in some cases.
[0021]
Further, since the leading end and the trailing end of the paper P are cut surfaces, paper dust is likely to be generated. For this reason, when the leading end and the trailing end of the sheet P pass through the transfer position S, a large amount of paper dust may fall on the charge wire 61.
In the present embodiment, the negative potential is applied to the charge wire 61 during the time interval B during which the sheet does not pass through the transfer position S, so that the negatively charged paper dust on the charge wire 61 An electrostatic repulsion is generated between them. Thus, the paper dust charged to the negative potential can be removed from the charge wire 61. Therefore, it is possible to prevent the transfer performance from being reduced due to the paper dust generated from the paper P.
[0022]
In particular, a large amount of paper dust placed on the charge wire 61 when the rear end of the sheet P passes through the transfer position S can be suitably removed before the succeeding sheet P passes through the transfer position S.
Further, by repeatedly turning on / off the application of the voltage to the charge wire 61 a plurality of times, the charge wire 61 can be vibrated, so that the paper dust can be more effectively removed.
[0023]
Most of the paper dust generated from the paper P is charged to a negative potential, but the toner charged to the positive potential may be attached to the positive potential or may not be charged due to the attachment of the toner. . In the present embodiment, the on / off of the application of the voltage to the charge wire 61 is repeated a plurality of times, and the charge wire 61 is vibrated, so that the positively charged paper dust and the uncharged paper dust can be effectively removed. Can be removed.
[0024]
The number of times (5 times) and the time (50 msec) of application of the voltage to the charge wire 61 at the time interval B are not limited to the above values, but if the application time is long, the toner or the image adhered to the surface of the photoreceptor 2 may be The toner floating in the forming apparatus (usually charged to a positive potential) may be attracted to and adhere to the charge wire 61, thereby deteriorating the transfer performance of the transfer apparatus 6. It is preferable to set the value to a value that does not cause serious adverse effects.
[0025]
In the present embodiment, a configuration in which a voltage is applied to the charge wire 61 during each time interval B when an image is formed on a plurality of sheets P has been described. However, the configuration is not limited to this configuration. In the case where the paper is jammed in the above (so-called JAM), after the processing for removing the jammed paper is performed, a voltage is applied to the charge wire 61 in response to a predetermined operation being performed. It may be.
When JAM occurs, a large amount of paper dust is generated when the jammed paper is removed. With the above configuration, the paper P sent after the jammed paper is removed is transferred to the transfer position. Until S is reached, the paper dust on the charge wire 61 can be effectively removed.
[0026]
The application of the voltage to the charge wire 61 for removing the paper dust on the charge wire 61 is not performed automatically, but, for example, an operation panel (not shown) for setting the operation content of the image forming apparatus. May be configured to be performed in response to a pressing operation of a predetermined button disposed in the.
In the present embodiment, a case where the toner is charged to a positive potential has been described, but a toner charged to a negative potential may be used. In this case, during the paper passing period A, a positive potential is applied to the charge wire 61 in order to attract the toner on the surface of the photoconductor 2 to the transfer device 6 side. In order to remove the dust, a configuration in which a negative potential is applied to the charge wire 61 may be adopted.
[0027]
The present invention is not limited to the contents of the above embodiments, and various modifications can be made within the scope of the claims.
For example, although a copying machine has been described as an embodiment of the present invention, the present invention is not limited to the copying machine, but can be applied to other image forming apparatuses such as a printer and a facsimile.
[Brief description of the drawings]
FIG. 1 is a schematic diagram illustrating a configuration of an image forming unit of an image forming apparatus according to an embodiment of the present disclosure.
FIG. 2 is a time chart showing an example of on / off control of voltage application to a charge wire.
[Explanation of symbols]
2 Photoconductor 6 Transfer device 61 Charge wire 11 Control unit B Time interval P Paper S Transfer position

Claims (3)

A transfer device for an image forming apparatus for transferring toner on a sheet at a transfer position by electrostatically attracting charged toner attached to a photoconductor surface, comprising:
An energizable charge wire disposed opposite the photoreceptor surface,
By applying a voltage to the charge wire so as to have a potential opposite to the charging potential of the toner, an application unit for electrostatically attracting the toner on the photoreceptor surface to the transfer device side,
The transfer device is characterized in that the application means can apply a predetermined voltage to the charge wire even when a sheet does not pass through the transfer position. In the case where transfer is continuously performed on a plurality of sheets, the application unit may be configured to transfer the charge wire after the transfer to the preceding sheet is completed and before the subsequent sheet reaches the transfer position. 2. The transfer device according to claim 1, wherein on / off of application of a voltage to the transfer device is repeated plural times. The application unit applies a voltage to the charge wire until a sheet that is subsequently sent reaches the transfer position when a process of removing a jammed sheet in the image forming apparatus is performed. The transfer device according to claim 1, wherein the transfer is applied.

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