JP2001092269A - Discharge device and image-forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image-forming device, capable of restraining the scattering of toner at the time of transferring a toner image formed on a toner image carrier such as a photoreceptor to a body to be transferred and satisfactorily forming an image all the more. SOLUTION: In this image-forming device A1, an electrostatic latent image is formed on a photoreceptor 91 and developed by a developing device 95 by using the toner electrified to be negative, and a toner image formed on the photoreceptor 91 is transferred to a recording sheet S by a transfer device 961. A discharge device D1 is arranged at a position, where it faces to the photoreceptor 91 between devices 95 and 961 so at to discharge the toner before transfer on the photoreceptor 91 from a discharge member 12, whereby the absolute value of the electrified amount of the toner is made high. By applying next oscillating voltage to the member 12 arranged proximately to the photoreceptor 91, the toner is electrified. An oscillating voltage, whose peak-to- peak voltage VPP is twice or more times as high as discharge start voltage, is applied to the member 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image forming apparatus for transferring a toner image formed on a toner image carrier such as a photoreceptor to a transfer member to form an image. The present invention also relates to an image forming apparatus for forming an image by sequentially superimposing and transferring a toner image onto a transfer target such as an intermediate transfer member and a recording sheet. Further, the present invention relates to an image forming apparatus in which a toner image transferred onto a recording sheet is fixed by a fixing device.

[0002]

2. Description of the Related Art In an image forming apparatus, for example, an electrostatic latent image based on a document image is formed on a photoreceptor, the electrostatic latent image is developed using toner, and a toner image formed on the photoreceptor is formed. Is transferred to a recording sheet, so that a toner image based on the document image is formed on the recording sheet.

In a color image forming apparatus, for example, a color toner image based on a document image is formed on a recording sheet as follows. In an intermediate transfer type color image forming apparatus, for example, cyan, magenta, yellow, and black toner images based on a document image are sequentially formed on a photoconductor,
Each time one toner image is formed, the toner image is temporarily transferred to an intermediate transfer member such as an intermediate transfer belt. The second and subsequent toner images formed on the photoreceptor are transferred so as to overlap the toner images already transferred on the intermediate transfer member. By transferring the toner images of all these colors onto the intermediate transfer body, a color toner image in which the respective color toner images based on the original image are laminated is formed on the intermediate transfer body. The color toner image is secondarily transferred onto the recording sheet at a time, whereby a color toner image based on the original image is formed on the recording sheet.
In a transfer drum type or tandem type color image forming apparatus, a color toner image based on a document image is formed on a recording sheet by directly transferring each color toner image onto a recording sheet instead of transferring to an intermediate transfer body. Is formed.
In a transfer drum type color image forming apparatus, at the time of image formation, a recording sheet onto which a toner image is transferred is carried on a sheet carrier such as a transfer drum and a transfer belt. A tandem-type color image forming apparatus has, for example, a photoconductor for each color, and a recording sheet on which a toner image is transferred is conveyed by a sheet conveyance device while sequentially facing each photoconductor at the time of image formation.

In any of the image forming apparatuses, the toner image transferred to the recording sheet is usually fixed by a fixing device.

[0005]

However, in an image forming apparatus which transfers a toner image formed on a photoreceptor to a transfer target such as a recording sheet or an intermediate transfer member to form an image, the toner image is transferred to the image forming apparatus. When the toner is transferred to the transfer medium, the toner may be scattered, and the toner image may not be successfully transferred onto the transfer medium.

In a color image forming apparatus of the intermediate transfer type, when a toner image is transferred onto a toner image already transferred on an intermediate transfer member, the toner images have the same charge polarity. May scatter, making it impossible to transfer a toner image onto the intermediate transfer member satisfactorily. A similar problem also occurs in a transfer drum type and tandem type color image forming apparatus in which a toner image is superimposedly transferred on a recording sheet. In the intermediate transfer type color image forming apparatus, when the laminated toner image formed on the intermediate transfer body is secondarily transferred onto the recording sheet, the toner scatters and the toner image is transferred well on the recording sheet. There are things you can't do.

[0007] Even when fixing is performed by a fixing device, the toner may be transferred to a fixing member such as a fixing roller or the toner may be scattered, so that good fixing may not be performed. Accordingly, it is an object of the present invention to provide an image forming apparatus capable of suppressing toner scattering and performing good image formation. Furthermore, the present invention can suppress the scattering of toner when transferring a toner image formed on a toner image carrier such as a photoreceptor to a transfer-receiving body, and can thereby perform an image formation that can perform good image formation. It is an object to provide a forming apparatus.

According to another aspect of the present invention, there is provided an image forming apparatus in which a toner image is sequentially transferred onto a transfer member such as an intermediate transfer member or a recording sheet, and the toner image is transferred onto the toner image already transferred onto the transfer member. It is an object of the present invention to provide an image forming apparatus capable of suppressing the scattering of toner when transferring the next toner image and performing good image formation accordingly. Further, the present invention is an image forming apparatus in which a toner image transferred onto a recording sheet is fixed by a fixing device, which can suppress scattering of toner generated at the time of fixing and offset of the toner to a fixing member. It is an object to provide an image forming apparatus capable of forming a good image.

Another object of the present invention is to provide a discharge device which can be used in an image forming apparatus to suppress scattering of toner.

[0010]

(1) Image Forming Apparatus In order to solve the above problems, the present invention relates to an image forming apparatus for forming a toner image based on a document image on a recording sheet, comprising: A discharge member that faces the toner carrying surface at a predetermined distance from the toner carrying surface of the carrier, and a voltage that applies a predetermined voltage to the discharge member to cause the discharge member to discharge toward the toner on the toner image carrier. A discharge device having an application device, wherein the voltage application device discharges the toner from the discharge member to the toner on the toner image carrier by applying a peak-to-peak voltage V _PP from the discharge member to the toner image carrier. An image forming apparatus is provided, wherein an oscillating voltage having a predetermined waveform that is twice or more a discharge starting voltage when discharging to toner on a body is applied to the discharging member.

[0011] The image forming apparatus of the present invention has a discharge device for discharging to the toner carried on the toner carrying surface of the toner image carrier. As described in detail below, the toner image carrier is, for example, an electrostatic latent image carrier such as a photoconductor, an intermediate transfer body, a recording sheet, or the like. Typically, discharging to the toner on the toner carrying surface is performed while moving the toner carrying surface of the toner image carrier in a predetermined direction with respect to the discharge member of the discharge device.

The discharging device includes a discharging member and a voltage applying device. The discharge member is separated from the toner carrying surface of the toner image carrier by a predetermined distance, and faces the toner carrying surface. When the toner image carrier is disposed at a fixed position such as an electrostatic latent image carrier or an intermediate transfer member as described later, the discharge member may be disposed at a position facing the toner image carrier. When the toner image carrier is a recording sheet that is conveyed by a sheet conveying device at the time of image formation, as described later, a discharge member may be arranged so that the moving recording sheet can face a predetermined position. . In any case, the discharge member is separated from the toner on the toner carrying surface by a predetermined distance and faces the toner. Although the shape of the discharge member may be any shape, a preferable shape will be described later.

The voltage applying device applies the following oscillating voltage to the discharge member in order to discharge the discharge member to the toner on the toner carrying surface. An oscillating voltage may be applied to the discharge member via an electrode brought into contact with the discharge member. When discharging from the discharging member to the toner on the toner image carrier,
An oscillating voltage having a predetermined waveform whose peak-to-peak voltage is V _PP is applied to the discharge member. The discharge member has a peak-to-peak voltage V _PP ,
An oscillating voltage that is at least twice the discharge starting voltage when the discharge member discharges to the toner on the toner carrying surface is applied.
The oscillating voltage applied to the discharge member is an AC voltage having a center voltage of V _DC and a peak-to-peak voltage of V _PP . The center voltage _VDC may be 0 [V]. The DC component voltage of the oscillating voltage is V _DC , and the peak-to-peak voltage of the AC component voltage is V _PP . The waveform of the oscillating voltage may be, for example, a rectangular wave, a sine wave, a triangular wave, or the like.

By applying such an oscillating voltage to the discharge member, the discharge member discharges the toner on the toner carrying surface. By this discharge, for example, the toner on the toner image carrier is charged. By this discharge, for example, the toner on the toner image carrier is charged, and at the same time, softened and aggregated. By this discharge, for example, the toner on the toner image carrier is charged and melted. This discharge softens and aggregates the toner on the toner image carrier, for example. By this discharge, for example, the toner on the toner image carrier is melted. The charging operation performed by the discharge device is an operation of changing the charge amount (charge potential) of the toner, and includes both an operation of increasing the charge amount of the toner and an operation of decreasing the charge amount. The discharge device can discharge toward the toner, for example, to increase the absolute value of the charge amount of the toner.
Further, the discharge device can discharge toward the toner to reduce the absolute value of the charge amount of the toner toward zero, in other words, can also perform the charge elimination of the toner. Discharge device, depending on the purpose of using the discharge device in the image forming apparatus,
The toner on the toner image carrier may be charged, aggregated, and melted.

Such a discharge device may be used in an image forming apparatus, for example, as described in the following (1-1) to (1-5). (1-1) Discharge to toner before transfer An image forming apparatus forms an electrostatic latent image carrier on which an electrostatic latent image is formed based on a document image, and converts the electrostatic latent image on the electrostatic latent image carrier into toner. And a transfer device for transferring the toner image formed on the electrostatic latent image carrier to a predetermined transfer target.

In this image forming apparatus, a toner image based on a document image is formed on a recording sheet as follows. An electrostatic latent image based on a document image is formed on an electrostatic latent image carrier, and the electrostatic latent image is developed by a developing device using a developer containing toner, so that the electrostatic latent image is formed on the electrostatic latent image carrier. A toner image based on the document image is formed. The electrostatic latent image carrier is, for example, a photoconductor. By directly transferring the toner image on the electrostatic latent image carrier onto the recording sheet, a toner image based on the original image can be formed on the recording sheet. Alternatively, a toner image based on a document image is formed on a recording sheet by temporarily transferring the toner image on the electrostatic latent image carrier to the intermediate transfer member and transferring the toner image on the intermediate transfer member to a recording sheet. can do. The transfer target (transfer target) onto which the toner image on the electrostatic latent image carrier is transferred is, for example, a recording sheet or an intermediate transfer member.

In this image forming apparatus, the toner image carrier facing the discharge member of the discharge device may be, for example, an electrostatic latent image carrier. For example, before the toner image formed on the electrostatic latent image carrier by the developing device is transferred to the transfer target by the transfer device, the discharging device discharges the toner on the electrostatic latent image carrier. Just do it. By increasing the absolute value of the charge amount of the toner on the electrostatic latent image carrier with a discharge device before the transfer, the effect of the transfer voltage when the toner image on the electrostatic latent image carrier is transferred to the transfer target body Thus, the scattering of the toner caused by the toner on the electrostatic latent image carrier jumping out before the transfer can be suppressed. Even if the toner on the electrostatic latent image carrier is softened and agglomerated by the discharging device before the transfer, the scattering of the toner during the transfer can be suppressed. Even if the toner on the electrostatic latent image carrier is melted by the discharge device before the transfer, the scattering of the toner during the transfer can be suppressed. (1-2) Discharge to Toner on Intermediate Transfer Member The image forming apparatus includes an electrostatic latent image carrier on which an electrostatic latent image is formed based on a document image, and an electrostatic latent image carrier on the electrostatic latent image carrier. A plurality of developing devices for developing an image using toner of a predetermined color, a primary transfer device for transferring a toner image formed on an electrostatic latent image carrier to an intermediate transfer member, and a transfer onto the intermediate transfer member And a secondary transfer device for transferring the transferred toner image onto the recording sheet.

This image forming apparatus can be used as a so-called intermediate transfer type color image forming apparatus. This image forming apparatus includes an electrostatic latent image carrier, a plurality of developing devices, an intermediate transfer member, a primary transfer device, and a secondary transfer device. Each of the plurality of developing devices can develop the electrostatic latent image formed on the electrostatic latent image carrier using a toner of a predetermined color. These developing devices may be, for example, three developing devices that develop each color of cyan, magenta, and yellow using toner. These developing devices may be, for example, four developing devices that develop each color of cyan, magenta, yellow, and black using toner.

In this image forming apparatus, a color toner image based on a document image can be formed on a recording sheet as follows. An electrostatic latent image of each color component of the document image is formed on the electrostatic latent image carrier in order. The electrostatic latent images formed on the electrostatic latent image carrier are sequentially developed by corresponding developing devices. As a result, a toner image of a predetermined color based on the document image is sequentially formed on the electrostatic latent image carrier. Each time a toner image is formed on the electrostatic latent image carrier, the toner image is temporarily transferred onto the intermediate transfer member by the primary transfer device. The second and subsequent toner images formed on the electrostatic latent image carrier are transferred so as to overlap the toner images already transferred on the intermediate transfer body. For example, cyan, magenta, yellow,
A black toner image is formed in this order, and a cyan toner image is first transferred to an intermediate transfer member. Next, the magenta toner image is transferred so as to overlap the cyan toner image on the intermediate transfer member. Thereafter, similarly, the yellow toner image and the black toner image are sequentially transferred so as to be superimposed on the toner image already transferred to the intermediate transfer member.
As a result, a color toner image based on the document image is formed on the intermediate transfer member. By transferring the color toner image on the intermediate transfer member onto the recording sheet by the secondary transfer device, a color toner image based on the original image is formed on the recording sheet. Thereafter, if necessary, the toner image on the recording sheet may be fixed by a fixing device.

In this image forming apparatus, the toner image bearing member facing the discharge member of the discharge device is, for example, an intermediate transfer member, for example, the following (1-2-1) and (1-2-
As described in 2), the discharge device may discharge the toner on the intermediate transfer member. (1-2-1) For example,
Before the next toner image is transferred over the toner image already transferred to the intermediate transfer member, the discharge device may discharge the toner already transferred to the intermediate transfer member. The discharge device reduces the absolute value of the amount of charge on the toner on the intermediate transfer body, thereby suppressing toner scattering that occurs when transferring the toner image on top of the toner image already transferred on the intermediate transfer body. it can. Even if the toner on the intermediate transfer member is aggregated by the discharge device, it is possible to suppress scattering of the toner when the toner images are superimposed and transferred. Even if the discharge device melts the toner on the intermediate transfer member, it is possible to suppress the scattering of the toner when the toner images are superimposed and transferred.

In discharging the toner to the toner that has already been transferred to the intermediate transfer member, the discharge device depends on the number of toner images to be transferred before the peak-to-peak voltage V _PP or the oscillating voltage applied to the discharge member. (And) The center voltage _VDC of the oscillating voltage may be changed. For example, when the cyan, magenta, yellow, and black toner images are transferred in this order on the intermediate transfer member as described above, the magenta toner image is transferred, the yellow toner image is transferred, and the black toner image is transferred. In this order, the peak-to-peak voltage V _PP of the oscillation voltage may be increased in order. Center voltage of oscillation voltage V _DC
May be sequentially reduced. The peak-to-peak voltage V _PP of the oscillating voltage may be sequentially increased, and the center voltage _VDC of the oscillating voltage may be sequentially reduced. Thus the peak-to-peak voltage V _PP of the oscillating voltage or (and) the center voltage V _DC, by changing depending prior to transferring the number th toner image, the peak voltage V _PP or (and) the center voltage V _DC The scattering of toner can be further suppressed as compared with the case where no change is made. (1-2-2) Before the toner image on the intermediate transfer member is transferred to the recording sheet by the secondary transfer device, discharge to the toner on the intermediate transfer member may be performed by a discharge device. The discharge device is
For example, after a multilayer toner image of a plurality of colors is formed on the intermediate transfer member, discharge to the multilayer toner image is performed before the secondary toner image is secondarily transferred to a recording sheet by a secondary transfer device. Just do it. By increasing the absolute value of the charge amount of the toner on the intermediate transfer member by the discharge device, scattering of the toner at the time of the secondary transfer can be suppressed. Even if the toner on the intermediate transfer member is aggregated by the discharge device, the scattering of the toner during the secondary transfer can be suppressed. Even if the toner on the intermediate transfer member is melted by the discharge device, the scattering of the toner during the secondary transfer can be suppressed.

In this intermediate transfer type image forming apparatus, as described in (1-1) above, a discharge device may be provided at a position facing the electrostatic latent image carrier. By discharging the toner on the electrostatic latent image carrier before the primary transfer, scattering of the toner at the time of the primary transfer can be suppressed. (1-3) Discharge to toner on recording sheet carried on sheet carrier The image forming apparatus comprises: an electrostatic latent image carrier on which an electrostatic latent image based on a document image is formed; A plurality of developing devices for developing the electrostatic latent image on the body using toner of a predetermined color, and a toner image formed on the electrostatic latent image carrier on a recording sheet carried on a sheet carrier. And a transfer device for transferring the image to the printer.

This image forming apparatus can be used as a so-called transfer drum type color image forming apparatus. This image forming apparatus includes an electrostatic latent image carrier, a plurality of developing devices, a sheet carrier, and a transfer device. The plurality of developing devices are
Each of the electrostatic latent images formed on the electrostatic latent image carrier can be developed using toner of a predetermined color.

In this image forming apparatus, a color toner image based on a document image can be formed on a recording sheet as follows. An electrostatic latent image of each color component of the document image is formed on the electrostatic latent image carrier in order. The electrostatic latent images formed on the electrostatic latent image carrier are sequentially developed by corresponding developing devices. As a result, a toner image of a predetermined color based on the document image is sequentially formed on the electrostatic latent image carrier. Each time a toner image is formed on the electrostatic latent image carrier, the toner image is transferred onto a recording sheet carried on the sheet carrier by a transfer device. The sheet carrier may be, for example, a rotating body such as a rotating drum or an endless rotating belt, and the recording sheet may be carried on the outer peripheral surface thereof. The second and subsequent toner images formed on the electrostatic latent image carrier are transferred to be superimposed on the toner images already transferred on the recording sheet carried on the sheet carrier. As a result, a color toner image based on the document image is formed on the recording sheet carried on the sheet carrier. Thereafter, the recording sheet is separated from the sheet carrier,
If necessary, the toner image on the recording sheet may be fixed by a fixing device.

In this image forming apparatus, the discharge device facing the discharge member of the discharge device is, for example, a recording sheet carried on the sheet support during image formation, and the discharge device is a recording sheet carried on the sheet support. The discharge to the toner on the sheet may be performed as follows. For example, before the next toner image is transferred over the toner image already transferred on the recording sheet carried on the sheet carrier, the discharge device discharges the toner already transferred onto the recording sheet. Should be performed. By lowering the absolute value of the charge amount of the toner on the recording sheet carried on the sheet carrier with a discharge device,
Overlay the toner image already transferred on the recording sheet,
It is possible to suppress toner scattering that occurs when the next toner image is transferred. Even if the discharge device causes the toner on the recording sheet carried on the sheet carrier to aggregate, the scattering of the toner can be suppressed. Even if the discharge device melts the toner on the recording sheet carried on the sheet carrier, the toner can be prevented from scattering.

In discharging the toner to the toner that has already been transferred onto the recording sheet carried on the sheet carrier, the discharge device may include any number of discharges as described in (1-2-1) above. The peak-to-peak voltage V _PP of the oscillating voltage applied to the discharge member or (and) the center voltage _VDC of the oscillating voltage may be changed depending on whether the toner image is to be transferred. The same effect can be obtained.

In this transfer drum type image forming apparatus, as described in (1-1) above, a discharge device may be provided at a position facing the electrostatic latent image carrier. By discharging the toner on the electrostatic latent image carrier before the transfer, the scattering of the toner during the transfer can be suppressed. (1-4) Discharge to Toner on Recording Sheet Conveyed by Sheet Conveying Apparatus A plurality of image forming apparatuses each capable of transferring a toner image of a predetermined color based on an original image onto the recording sheet. A unit and a sheet conveying device for conveying a recording sheet while sequentially approaching each of the image forming units.

This image forming apparatus can be used as a so-called tandem type color image forming apparatus. This image forming apparatus includes a plurality of image forming units and a sheet conveying device. The sheet conveying device conveys the recording sheet while sequentially facing each of the image forming units. The sheet conveying device has a sheet conveying body in the form of a rotating body such as an endless belt for holding a recording sheet, and is driven on the outer peripheral surface of the sheet conveying body by rotating the sheet conveying body. Recording sheet can be conveyed. The sheet conveying device may have one or more sheet conveying rollers. Each of the plurality of image forming units can form a toner image of a predetermined color based on a document image and transfer the toner image onto a recording sheet. These image forming units may be, for example, three image forming units that transfer toner images of cyan, magenta, and yellow on a recording sheet. These image forming units may be four image forming units that transfer toner images of respective colors of cyan, magenta, yellow, and black onto a recording sheet. The image forming unit is, for example, a unit that forms an electrostatic latent image on an electrostatic latent image carrier, develops the electrostatic latent image to form a toner image, and transfers the toner image onto a recording sheet. Just fine.

In this image forming apparatus, for example, a color toner image based on a document image can be formed on a recording sheet as follows. In each image forming unit, a toner image is formed for each color component of the original image, and these toner images are sequentially transferred onto a recording sheet conveyed by a sheet conveying device. The second and subsequent toner images transferred onto the recording sheet are transferred so as to overlap the toner images already transferred onto the recording sheet. As a result, a color toner image based on the document image is formed on the recording sheet conveyed by the sheet conveying device. Thereafter, if necessary, the toner image on the recording sheet may be fixed by a fixing device.

In this image forming apparatus, the toner image bearing member facing the discharging member of the discharging device is used as a recording sheet conveyed by a sheet conveying device during image formation, for example.
The discharging device may discharge the toner on the recording sheet conveyed by the sheet conveying device. For example, before the next toner image is transferred over the toner image already transferred on the recording sheet conveyed by the sheet conveying device, the discharging device discharges the toner already transferred onto the recording sheet. Should be performed. The discharge device reduces the absolute value of the charge amount of the toner that has already been transferred onto the recording sheet, so that toner generated when the next toner image is transferred over the toner image that has already been transferred onto the recording sheet. Can be suppressed. Even when the discharge device aggregates the toner on the recording sheet,
The scattering of the toner can be suppressed. Even if the discharge device melts the toner on the recording sheet, the scattering of the toner can be suppressed. When the image forming apparatus includes three or more image forming units, two or more discharge devices may be provided.

The discharge device discharges the toner that has already been transferred onto the recording sheet conveyed by the sheet conveying device, as described in the above (1-2-1).
The peak-to-peak voltage V _PP of the oscillating voltage applied to the discharge member or the center voltage _VDC of the oscillating voltage may be changed depending on the number of the toner image before the transfer. The same effect can be obtained.

Also in this tandem type image forming apparatus, when the image forming unit has an electrostatic latent image carrier, as described in (1-1) above, the image forming unit faces the electrostatic latent image carrier. A discharge device may be provided at the position. Before the transfer of the toner image from the electrostatic latent image carrier to the recording sheet, the discharge device discharges the toner on the electrostatic latent image carrier, so that scattering of the toner during transfer can be suppressed. (1-5) Discharge to toner before fixing An image forming apparatus transfers a toner image based on a document image onto a recording sheet, and the toner image transferred onto the recording sheet is fixed to the recording sheet. When a fixing device is provided.

This image forming apparatus includes an image forming device and a fixing device. The image forming apparatus forms a toner image based on a document image, and transfers the toner image onto a recording sheet. Note that any of the image forming apparatuses described in (1-1) to (1-4) includes an image forming apparatus that transfers a toner image based on a document image onto a recording sheet as described above.
The fixing device fixes the toner image transferred on the recording sheet to the recording sheet. The fixing device has, for example, two fixing members. These fixing members are, for example, rollers. The two fixing members are opposed to each other, and the fixing is performed by passing a recording sheet carrying a toner image through a nip portion of these fixing members. By providing a heating device for heating one or both fixing members, and applying heat to the toner, heat fixing can be performed. Pressure contact can be performed by pressing one fixing member against the other fixing member. Heat and pressure fixing may be possible.

In this image forming apparatus, the toner image carrier facing the discharge member of the discharge device is used as a recording sheet on which the toner image is transferred by, for example, an image forming device, and the fixing device fixes the toner image on the recording sheet. Before the discharge, the discharge device may discharge the toner on the recording sheet. When the image forming apparatus includes a sheet conveying device for conveying the recording sheet onto which the toner image has been transferred by the image forming device to the fixing device, after the toner image is transferred by the image forming device, Before the toner image on the recording sheet is fixed by the fixing device, the discharging device may discharge the toner on the recording sheet conveyed to the fixing device by the sheet conveying device. The discharge device charges the toner image on the recording sheet to the same polarity as the frictional charging polarity of the fixing member (toner contact fixing member) on the side of the two fixing members that contacts the toner image on the recording sheet, When the recording sheet enters the nip portion of the fixing member, the toner can be prevented from jumping to the toner contact fixing member, and the toner can be prevented from scattering and transferring to the fixing member. The toner on the recording sheet is charged to the same polarity as the frictional charging polarity of the toner contact fixing member by setting the center voltage _VDC of the vibration voltage applied to the discharging member to the same polarity as the frictional charging polarity of the toner contact fixing member. be able to. Even if the toner on the recording sheet is aggregated before fixing, scattering of the toner at the time of fixing can be suppressed. Even if the toner on the recording sheet is melted before fixing, scattering of the toner at the time of fixing can be suppressed.

As described in (1-1) to (1-5), the oscillating voltage is applied to the discharge member facing the toner image carrier in the image forming apparatus, and the toner is applied to the toner on the toner image carrier. By performing the discharge, it is possible to suppress the scattering of the toner and the like and to form a good image as described above. When the discharge device discharges and charges the toner on the toner image carrier, an oscillating voltage in which the peak-to-peak voltage V _PP is twice or more the discharge start voltage is applied to the discharge member, so that there is environmental fluctuation. Even if the gap between the discharging member and the toner image carrier slightly fluctuates, the toner can be uniformly charged.

The surface of the discharge member facing the toner carrying surface of the toner image carrier has, for example, an area in which the distance to the toner carrying surface gradually increases toward the downstream side in the toner carrying surface moving direction. Just fine. When the toner is charged by the discharge device without aggregating and melting the toner on the toner image carrier, it is preferable that such a region is provided to uniformly charge the toner image. Furthermore, in order to uniformly charge the toner image on the toner image carrier, the surface of the discharge member facing the toner carrying surface gradually increases in distance from the discharge area to the toner carrying surface as going downstream. It is preferable that the shape be larger.

By applying an oscillating voltage to the discharge member, the toner on the toner image carrier may be softened and aggregated as described above. For example, by increasing the peak-to-peak voltage V _PP of the oscillation voltage, the toner on the toner image carrier can be softened and aggregated. Even if the toner on the toner image carrier is aggregated, problems such as scattering of the toner can be suppressed.

As described above, the toner on the toner image carrier may be melted by applying an oscillating voltage to the discharge member. For example, by increasing the peak-to-peak voltage V _PP of the oscillation voltage, the toner on the toner image carrier can be melted. When the toner on the toner image carrier is melted and the toner on the toner image carrier is transferred to a transfer target such as a recording sheet, the toner image is electrostatically transferred depending on the degree of melting of the toner. Instead, the toner image can be transferred only by the pressure. Even when the toner on the toner image carrier is melted, problems such as scattering of the toner can be suppressed.

The discharge member surface facing the toner carrying surface may have a region substantially parallel to the toner carrying surface (region along the toner carrying surface). When the discharge member has such a region, the toner on the toner carrying surface can be aggregated or melted without increasing the peak-to-peak voltage V _PP of the oscillation voltage. Also, if the waveform of the oscillating voltage is a rectangular wave, the peak-to-peak voltage V _PP of the oscillating voltage is not so much increased and the frequency of the oscillating voltage is not so increased as compared with the case of forming a sine wave or the like. Can be aggregated or melted.

In any case, since the discharge member is separated from the toner carrying surface, it is possible to prevent the discharge member from being stained due to transfer of the toner and the like. Thus, good discharge can be performed from the discharge member for a long time. If the discharge member is arranged close to the toner carrying surface, the amount of ozone generated can be reduced. In order to perform good discharge from the discharge member, the surface resistance of the discharge member may be, for example, about 10 ³ Ω / □ to about 10 ¹⁰ Ω / □. The discharge member may be made of a material in which a conductive material such as carbon is dispersed in a resin such as polyimide, polyamide, ETFE, PVdF, polyurethane, or silicone.

In order to stabilize the distance (gap) between the discharge member and the toner carrying surface, the following positioning member may be provided. The positioning member is disposed between the discharge member and the toner carrying surface. The positioning member is brought into contact with the discharge member. In other words, the discharge member is brought into contact with the positioning member. The positioning member and the discharge member may be fixed by an adhesive or the like to be integrated. The positioning member is also brought into contact with the toner carrying surface. The positioning member may be brought into contact with a non-image area on the toner carrying surface, for example. When the toner carrying surface is the recording sheet surface, the positioning member may be brought into contact with, for example, a sheet carrier that carries the recording sheet. Since the positioning member for contacting the discharge member is brought into contact with the toner carrying surface or the like, the distance between the discharge member and the toner carrying surface can be stabilized, and the discharge distance can be stabilized. Thereby, favorable discharge can be performed. Further, the discharge member can be easily arranged close to the toner carrying surface by the positioning member. The positioning member is, for example, an insulating material,
What is necessary is just to consist of a resistance material. (2) Discharge device The present invention also provides the following discharge device that can be used in the above-described image forming apparatus of the present invention.

According to the present invention, there is provided a discharge device for discharging to a toner carried on a toner image carrier in an image forming apparatus, wherein the toner carrying surface is separated from the toner carrying surface of the toner image carrier by a predetermined distance. And a voltage application device for applying a predetermined voltage to the discharge member to cause the discharge member to discharge toward the toner on the toner image carrier.The voltage application device includes: Applying a vibration voltage of a predetermined waveform to the discharge member, wherein a peak-to-peak voltage V _PP is at least twice the discharge start voltage when the discharge member discharges to the toner on the toner image carrier. Provide equipment.

By using this discharge device in an image forming apparatus as described above, it is possible to suppress problems such as toner scattering as described above.

[0044]

Embodiments of the present invention will be described below with reference to the drawings. (1) FIG. 1 shows a schematic configuration diagram of an example of an image forming apparatus according to the present invention. The image forming apparatus A1 shown in FIG. 1 is a discharge device according to the present invention for adjusting the charge amount of a toner image formed on a photoconductor before transferring it to a recording sheet, as will be described in detail later. D1 is provided.

The image forming apparatus A1 shown in FIG. 1 is an electrophotographic monochrome image forming apparatus. Image forming apparatus A1
Has a drum-shaped photosensitive member 91 for forming a toner image based on an original image on a recording sheet by electrophotography. The photoreceptor 91 has a photoconductor layer formed on a drum-shaped conductive support layer, and the conductive support layer is grounded. Around the photoreceptor 91, an eraser lamp 92, a charging charger 93, a laser device 94, a developing device 9
5. Discharge device D1, transfer device 961, and cleaning device 97 according to the present invention are arranged in this order.

The image forming apparatus A1 can form a toner image based on a document image on a recording sheet as follows. In addition, about the structure and operation | movement of the discharge device D1,
After a method of forming a toner image is described, it will be described in detail. At the time of image formation, the photoconductor 91 is driven to rotate clockwise in FIG. 1 by a driving device (not shown). Photoreceptor outer peripheral surface 9
The photoconductor 91 is rotationally driven so that 11 moves.

First, by irradiating light from the eraser lamp 92, the charge on the outer peripheral surface 911 of the photosensitive member is removed. Then
The outer peripheral surface 911 of the photoconductor is uniformly charged by the charging charger 93. In this example, the outer peripheral surface 911 of the photoconductor is
Charge to 600V. By irradiating the charged photoconductor outer peripheral surface 911 with light from the laser device 94 based on the original image, the potential of the exposed portion is attenuated. In this example, the potential of the exposed surface of the photoconductor outer peripheral surface 911 is about −10.
Attenuates to 0V. As a result, an electrostatic latent image based on the document image is formed on the outer peripheral surface 911 of the photoconductor. This electrostatic latent image is developed by the developing device 95 using negatively charged toner.
The developing device 95 has a developing roller 951 facing the photoconductor 91. By applying a developing bias voltage to the developing roller 951, the negatively charged toner carried by the developing roller 951 is exposed to the exposed portion of the photoconductor outer peripheral surface 911. Can be transferred to In this example, DC-300 V is applied to the developing roller 951 as a developing bias voltage. Developing device 95
Performs so-called reversal development. As the developing device 95 develops the electrostatic latent image, a toner image based on the document image is formed on the outer peripheral surface 911 of the photoconductor.

The toner image on the outer peripheral surface 911 of the photoreceptor is transferred onto the recording sheet S supplied between the photoreceptor 91 and the transfer roller 961r of the transfer device 961. Transfer roller 96
By applying a transfer bias voltage to 1r from the power supply 961s, the toner image on the photoconductor 91 is electrostatically transferred onto the recording sheet S. In this example, a positive voltage is applied to the transfer roller 961r. The toner remaining on the photoconductor 91 without being transferred to the recording sheet is removed by the cleaning device 97.

The recording sheet S on which the toner image has been transferred is separated from the photosensitive member 91 and is conveyed to the fixing device 98. After the fixing of the toner image in the fixing device 98, the recording sheet S is discharged out of the image forming apparatus. In the image forming apparatus A1, the toner image based on the document image is formed on the recording sheet in this manner. Image forming apparatus A1
The transfer device 961
The discharge device D1 is disposed between the developing device 95 and the transfer device 961 as described above in order to suppress the scattering of the toner generated when the toner image is transferred onto the recording sheet. In the image forming apparatus A1, scattering of toner during transfer can be suppressed by the discharge device D1 as follows.

First, the configuration of the discharge device D1 will be described. The discharge device D1 is a discharge unit 1 facing the photoconductor 91.
And a voltage application device 2. FIG. 2 shows a schematic perspective view of the discharge unit 1. A schematic side view of the discharge unit 1 is shown in FIG. FIG. 4 is an enlarged view of a peripheral portion of the discharge unit 1.

The discharge unit 1 includes an electrode 11, a discharge member 1
2 and positioning members 131 and 132. The electrode 11 is a rod having a semicircular cross section, and extends in the rotation axis direction of the photoconductor 91. The electrode 11 is made of a conductive material and is electrically connected to the voltage applying device 2. The discharge member is 12
Is a film that covers the circumferential surface (arc surface) of the electrode 11 and extends in the rotation axis direction of the photoconductor 91. The discharge member 12 is adhered to the electrode 11 by a conductive adhesive. The discharge member 12 has an arc-shaped cross section. In order to make the cross-sectional shape of the discharge member 12 arc-shaped, the cross-sectional shape of the electrode 11 is semicircular. By winding a film around the electrode 11 using the electrode 11 as a core material, an arc-shaped discharge member 12 is formed.

The thickness of the discharge member (film) 12 is 100 μm in this example. The thickness of the discharge member 12 is 50 to
It may be about 200 μm. In this embodiment, the discharge member 12 is made of a resistance material in which carbon is dispersed in polyimide, and has a surface resistance of 10 ⁸ Ω / □. Discharge member 12
Examples of the material include polyimide, polyamide, ETFE,
A resistance material in which a conductive material such as carbon is dispersed in a resin such as PVdF, polyurethane, or silicone may be employed. The surface resistance of the discharge member 12 is 10 ³ Ω / □ to 10 ¹⁰ Ω
/ □.

The positioning members 131 and 132 are insulating films wound around both ends of the discharge member 12 in the photoconductor rotation axis direction. Positioning members 131, 132
Are bonded to the discharge member 12 with an adhesive. In this example, the positioning members 131 and 132 have a thickness of 50 μm,
A polyimide film having a width of 2 cm in the rotation axis direction of the photoconductor.

The discharge unit 1 including the electrode 11, the discharge member 12, and the positioning members 131 and 132 is integrated by bonding the contact surfaces to each other with an adhesive as described above. The positioning members 131 and 132 of the discharge unit 1 are in contact with the outer peripheral surface 911 of the photoconductor. Positioning member 13
Reference numerals 1 and 132 are in contact with an area of the outer peripheral surface 911 of the photoconductor where no toner image is formed.

Since the positioning members 131 and 132 having a predetermined thickness are in contact with the outer peripheral surface 911 of the photosensitive member, the discharging member 1 is formed.
The second circumferential surface (arc surface) 121 is separated from the outer circumferential surface 911 of the photoconductor by a predetermined distance. More specifically, when the toner image formed on the outer peripheral surface 911 of the photoconductor in the developing device 95 passes through a position facing the discharge unit 1, the toner image is separated from the outer peripheral surface 121 of the discharge member by a predetermined distance. Photoreceptor outer peripheral surface 9
11 (toner image on the outer peripheral surface 911 of the photoconductor) and the peripheral surface 121 of the discharge member so that the positioning member 1
The thicknesses of 31 and 132 are determined. Positioning member 1
The discharge member 12 can be easily arranged close to the outer peripheral surface 911 of the photoconductor by bringing the outer peripheral surface 911 into contact with the outer peripheral surface 911 of the photoconductor.

The voltage applying device 2 connected to the electrode 11
Has a DC power supply 21 and an AC power supply 22 connected in series. The voltage application device 2 can apply an oscillating voltage obtained by superimposing an AC voltage having a predetermined waveform on a DC voltage to the discharge member 12 via the electrode 11. In this example, the voltage application device 2 applies a rectangular wave-shaped vibration voltage to the discharge member 12 as shown in FIG. The voltage applying device 2 applies an oscillating voltage having a peak-to-peak voltage (peak-to-peak voltage) of V _PP and a center voltage of _VDC to the discharge member 12. The polarity of the center voltage _VDC is the same as the polarity of the charged toner on the photosensitive member 91 (in this example, negative polarity). Voltage application device 2
Is the oscillation voltage at which the peak-to-peak voltage V _PP is twice or more the discharge starting voltage V _TH when a DC voltage is applied to the discharge member 12 and the discharge member 12 discharges to the uncharged photoconductor 91. Applied to the discharge member 12. In this example, since the gap g from the discharge member 12 to the photosensitive member 91 is 50 μm as described above, the discharge start voltage V _TH is about 62 μm.
0 V, and the peak-to-peak voltage V _PP of the oscillation voltage is about 1240.
V or more.

In the image forming apparatus A1 including the discharging device D1, such an oscillating voltage is applied to the discharging member 12 during image formation, and the toner image formed on the photosensitive member outer peripheral surface 911 and the photosensitive member from the discharging member 12 is formed. Discharge toward.
In the image forming apparatus A1, the peak-to-peak voltage V _PP = 2.0
kV, center voltage V _DC = -500V, frequency f = 600H
When an image was formed by applying a z-wave oscillation voltage in the form of a rectangular wave to the discharge member 12, scattering of toner during transfer could be suppressed as compared to when no voltage was applied to the discharge member 12. (2) In the image forming apparatus A1 including the discharge device D1, an experiment (Experiment 1) was performed in which the oscillating voltages V _PP and _VDC applied to the discharge member 12 were changed to check the occurrence of toner scattering. The frequency f of the oscillating voltage is 600H
The experiment was performed with z and a waveform as a rectangular wave. By observing the toner image transferred onto the recording sheet, the state of occurrence of toner scattering was examined. The results are shown in Table 1 below. Table 1 also shows the transfer voltage applied to the transfer roller 961r.

[0058]

[Table 1]

In Table 1, “○” indicates that there was no toner scattering and that toner scattering was prevented.
“△” indicates that the toner scattered a little, and that the toner scatter was suppressed. “X” indicates that toner scattered. "-" Indicates that the toner was not transferred from the photoconductor to the recording sheet.

When V _DC = 0 V and V _PP ≦ 3.2 kV, no toner image was transferred to the recording sheet at any transfer voltage. V _DC = 0V, V _PP ≧
At 3.6 kV, the toner image was transferred to the recording sheet regardless of the value of the transfer voltage. V _DC = 0
When V and V _PP = 3.6 kV, the density of the toner image transferred to the recording sheet was light, but there was no scattering of the toner.

When the peak-to-peak voltage V _PP is in the range of 1.8 to 2.8 kV, it is understood that the greater the absolute value of the voltage _VDC , the higher the effect of suppressing toner scattering. In this range, as the absolute value of the charge amount of the toner on the photoconductor 91 increases, the adhesion of the toner to the photoconductor 91 increases, and the scattering of the toner can be suppressed. If the absolute value of the voltage _VDC is increased, the absolute value of the charge amount of the toner is further increased, the electrostatic adhesion of the toner to the photoconductor 91 is further increased, and the effect of suppressing toner scattering is enhanced.

When the peak-to-peak voltage V _PP is 3.2 kV or more,
Microscopic observation revealed that part of the toner melted on the photoreceptor 91 and aggregated with each other. It is considered that the toner is aggregated by the heat generated by the discharge current. It is considered that the toner is hardly scattered due to the aggregation of the toner. 3. The peak-to-peak voltage V _PP is 4.
At 0 kV or more, the toner on the photoconductor 91 was completely melted. It is considered that the toner is melted by heat generated by the discharge current. It is considered that the toner is less likely to be scattered due to the melting of the toner. When the peak-to-peak voltage V _PP is 4.0 kV or more, the transfer roller 961r
The toner image was transferred onto the recording sheet only by applying pressure without applying a transfer voltage to the recording sheet.

From these results, it is found that an oscillating voltage is applied to the discharge member 12 at the time of image formation, and discharge from the discharge member 12 to the toner formed on the photosensitive member (toner image carrier) before transfer is performed. By increasing the absolute value of the charge amount of the toner on the body 91, by aggregating the toner on the photosensitive body 91, or by melting the toner on the photosensitive body 91,
It can be seen that toner scattering at the time of transfer can be suppressed.
If the absolute value of the center voltage (DC component voltage) _VDC of the oscillating voltage is increased, the absolute value of the charge amount of the toner can be further increased, and the attraction force of the toner to the photosensitive member 91 is further increased. Can be further suppressed.

A similar experiment was conducted by changing the waveform of the oscillating voltage from a rectangular wave to a sine wave or a triangular wave.
After the upper toner image passed through the area facing the discharge member 12, it scattered on the photoconductor 91, and the discharge member 12 was also stained with toner. It is considered that the toner moved between the photoconductor and the discharge member 12 and the toner scattered.
In the case where the oscillating voltage has a sinusoidal waveform, scattering of the toner can be improved by increasing the frequency of the oscillating voltage. From these, it can be seen that when the frequency of the oscillating voltage is relatively low, the waveform of the oscillating voltage applied to the discharge member is preferably a rectangular wave. (3) A similar experiment was performed using the discharge member 14 shown in FIG. 6 instead of the discharge member 12 shown in FIG. The discharge member 14 has a downstream portion that is substantially parallel to the outer peripheral surface 911 of the photoconductor.

When an oscillating voltage is applied to the discharge member 14 of FIG. 6 to form an image, the peak-to-peak voltage V
_{When the PP} was 2.8 kV or less, the transferability of a solid image deteriorated. When the frequency of the oscillating voltage was reduced, a band-like shading having a width corresponding to the frequency parallel to the photoconductor rotation axis direction occurred in the image transferred to the recording sheet. Discharge member 1 of FIG.
No. 2 does not occur in the image transferred to the recording sheet even when the image is formed by applying the same low frequency vibration voltage to the image No. 2.

From the above, it is understood that the shape of the discharge member to which the oscillating voltage is applied affects the charging uniformity of the toner image. When the peak-to-peak voltage V _PP is relatively small, for example, when the peak-to-peak voltage V _PP is set to a value that does not cause aggregation of the toner, the shape of the discharge member to which the oscillating voltage is applied is the same as that of the discharge member 12. The shape may be such that the distance from the toner on the surface 91 to the discharge member gradually increases as going downstream from the discharge region. By setting the shape of the discharge member to such a shape, the toner image on the photoconductor 91 can be uniformly charged. By doing so, when the toner image on the photoreceptor 91 passes through the area facing the discharge member, the oscillating electric field applied to the toner becomes weaker toward the downstream side.

When an image is formed by applying an oscillating voltage to the discharge member 14, the peak-to-peak voltage V _PP becomes 3.2.
If kV or more, the toner melted on the photoreceptor 91.
When the discharge member 12 was used, the toner melted when the peak-to-peak voltage V _PP was 4.0 kV or more as described above. From these, to aggregate or fuse the toner,
It can be seen that the use of the discharge member 14 rather than the discharge member 12 can reduce the peak-to-peak voltage V _PP of the oscillation voltage. (4) Conventionally, it has been proposed to apply a DC voltage to a discharge member disposed close to a photoreceptor to charge a toner image on the photoreceptor before transfer, thereby suppressing toner scattering during transfer. Have been. However, according to the conventional method of applying a DC voltage to the discharge member, even if the scattering of the toner at the time of transfer can be suppressed, the toner image on the photoreceptor can be uniformly charged when environmental conditions (particularly humidity) fluctuate. No, poor transfer is likely to occur. Further, in this conventional method, even if the distance (gap) between the discharge member and the photoconductor varies, the toner image on the photoconductor cannot be uniformly charged, and transfer failure tends to occur. Further, in the conventional method of applying a DC voltage to the discharge member, it is difficult to coagulate or melt the toner on the photoconductor.

On the other hand, the discharge device D1 having the discharge member 12 of the present invention and the discharge device D having the discharge member 14 according to the present invention.
In 2, the discharge member disposed close to the photoconductor 91 includes:
Since an oscillating voltage having a peak-to-peak voltage V _PP equal to or more than twice the discharge starting voltage V _TH is applied, even if the environmental conditions fluctuate or the gap between the discharge member and the photoconductor 91 fluctuates slightly, the photoconductor 91 The upper toner can be uniformly charged. Therefore, it is possible to suppress transfer failure caused by uneven charging of the toner image on the photoconductor 91. (5) FIG. 7 shows a schematic configuration diagram of another example of the image forming apparatus according to the present invention.

The image forming apparatus A3 shown in FIG. 7 is an intermediate transfer type color image forming apparatus. In the image forming apparatus A3, an eraser lamp 92 around the photoconductor 91,
A charging charger 93, a laser device 94, a cyan developing device 95C, a magenta developing device 95M, a yellow developing device 95Y, a black developing device 95K, an intermediate transfer belt 4, and a cleaning device 97 are arranged in this order.

The intermediate transfer belt 4 is an endless belt wound around rollers r1 to r4, and a part of its outer peripheral surface is in contact with the outer peripheral surface 911 of the photoconductor. Intermediate transfer belt 4
Is a position where it contacts the photoconductor 91, and a primary transfer device 961 is disposed on the inner peripheral surface side of the intermediate transfer belt.
Further, a secondary transfer device 962 is disposed at a position facing the roller r4 and on the outer peripheral surface side of the intermediate transfer belt.
The transfer roller 962r of the secondary transfer device 962 can be moved between a contact position where the transfer roller 962 contacts the intermediate transfer belt 4 and a separation position where the transfer roller 962r does not contact the intermediate transfer belt 4. Secondary transfer roller 962r
Is disposed at the contact position only when the toner image on the intermediate transfer belt 4 is transferred onto the recording sheet S.

The image forming apparatus A3 can form a color toner image on the recording sheet S based on the original image as follows. During image formation, the photosensitive member 91 is driven to rotate clockwise in FIG. 7, and the intermediate transfer belt 4 is driven to rotate counterclockwise in FIG. First, an electrostatic latent image corresponding to a cyan component original image is formed on the photoreceptor 91 in the same manner as the image forming apparatus A1, and is developed using cyan toner by the cyan developing device 95C. In the present embodiment, the developing device 95C performs development using negatively charged toner. The cyan toner image formed on the photoconductor 91 is temporarily transferred onto the intermediate transfer belt 4 by the primary transfer device 961. Similarly, magenta, yellow,
A black toner image is sequentially formed, and each time a toner image of each color is formed, the toner image is transferred so as to be superimposed on the toner image already transferred on the intermediate transfer belt 4. Developing device 95M,
95Y and 95K are developed using negatively charged toner, similarly to the developing device 95C. As a result, a color toner image in which cyan, magenta, yellow, and black toner images are stacked on the intermediate transfer belt 4 is formed. The color toner image on the intermediate transfer belt 4 is transferred onto the recording sheet S by the secondary transfer device 962. The recording sheet S on which the color toner image has been transferred is conveyed to a fixing device 98, and the fixing device 98
After fixing, the sheet is discharged to the outside of the image forming apparatus.

In the image forming apparatus A3, a discharge device D1 is disposed at a position facing the outer peripheral surface of the intermediate transfer belt 4. Furthermore, the discharge device D1 is disposed between the primary transfer area and the secondary transfer area. The roller r1 facing the discharge unit 1 of the discharge device D1 is grounded. The discharge device D1 is arranged at this position to suppress the following problem.

In the image forming apparatus A3, as described above, cyan, magenta, yellow, and black toner images are sequentially transferred from the photosensitive member 91 onto the intermediate transfer belt 4. A discharge device D1 is provided to suppress the scattering of toner that occurs when a toner image of another color is transferred on the toner image already transferred on the intermediate transfer belt 4.

Further, a discharge device D1 is provided in order to suppress scattering of toner which occurs when the color toner image on the intermediate transfer belt 4 is secondarily transferred to the recording sheet S. In the image forming apparatus A3, the discharge device D1 is used as described in the following (5-1) and (5-2). (5-1) To prevent toner scattering when transferring a toner image on a toner image already transferred on the intermediate transfer belt 4, the toner already transferred on the intermediate transfer belt 4 The absolute value of the charge amount of the image is lowered by the discharging device D1 before the next toner image is transferred over the toner image.

More specifically, after the cyan toner image is transferred onto the intermediate transfer belt 4 and before the next magenta toner image is transferred, the discharging device D1 charges the cyan toner on the intermediate transfer belt 4. Decrease the absolute value of the quantity. An oscillating voltage having a peak-to-peak voltage of V _PP and a center voltage of _VDC is applied to the discharging member 12 to discharge the discharging member 12 to the cyan toner image on the intermediate transfer belt 4, and the charge amount of the cyan toner Decrease the value. In this example, since the toner is negatively charged, the center voltage _VDC of the oscillating voltage applied to the discharge member 12 is negative and has an absolute value lower than the surface potential of the cyan toner layer on the intermediate transfer belt 4. Value. By reducing the absolute value of the charge amount of the cyan toner on the intermediate transfer belt 4, it is possible to suppress the scattering of toner that occurs when a magenta toner image is transferred from the photoconductor 91 to the cyan toner image.

After the magenta toner image is overlaid on the cyan toner image and before the next yellow toner image is transferred, the absolute value of the charge amount of the cyan and magenta laminated toner images on the intermediate transfer belt 4 is determined by the discharging device D1. And lower it in the same way. This makes it possible to prevent the toner from scattering when the yellow toner image is transferred onto the toner image already transferred on the intermediate transfer belt 4.

Further, before primary transfer of the next black toner image, cyan, magenta,
The discharge device D1 similarly lowers the absolute value of the charge amount of the yellow color toner image. This makes it possible to prevent the toner from scattering when the black toner image is transferred onto the toner image already transferred on the intermediate transfer belt 4. In this manner, when suppressing the scattering of the toner when the next toner image is transferred by being superimposed on the toner image already transferred on the intermediate transfer belt 4 by using the discharging device D1, the toner is applied to the discharging member 12. Although the center voltage V _DC and the peak-to-peak voltage V _PP of the oscillating voltage may always be the same, the center voltage V _DC and / or the peak-to-peak voltage V _PP may be set before the transfer of any toner image as follows. Depending on the order, the order in which the toner images are transferred may be changed.

For example, when discharging the toner on the intermediate transfer belt 4 before the primary transfer of the magenta toner image,
Intermediate transfer belt 4 before primary transfer of yellow toner image
When discharging to the upper toner, the absolute value of the center voltage _VDC may be reduced in the order of discharging to the toner on the intermediate transfer belt 4 before the primary transfer of the black toner image. . By changing the center voltage _VDC of the oscillation voltage in this manner, scattering of toner can be suppressed as compared with a case where the center voltage _VDC is not changed.

When discharging to the toner on the intermediate transfer belt 4 before the primary transfer of the magenta toner image is performed, and when discharging to the toner on the intermediate transfer belt 4 before the primary transfer of the yellow toner image is performed. Alternatively, the peak-to-peak voltage V _PP may be increased in the order of discharging to the toner on the intermediate transfer belt 4 before the primary transfer of the black toner image. By changing the peak-to-peak voltage V _PP of the oscillation voltage in this way, scattering of toner can be suppressed as compared with a case where the peak-to-peak voltage V _PP is not changed.

Both the center voltage V _DC and the peak-to-peak voltage V _PP may be changed in the same manner as described above. The discharge device D1 overlaps the toner image already transferred on the intermediate transfer belt 4 with
Before transferring the toner image, the toner on the intermediate transfer belt 4 may be discharged to aggregate or melt the toner. Even in this case, it is possible to suppress scattering when the next toner image is transferred while being superimposed on the toner image already transferred on the intermediate transfer belt 4. (5-2) In the image forming apparatus A3, before the cyan, magenta, yellow, and black toner images laminated and formed on the intermediate transfer belt 4 are collectively secondary-transferred onto the recording sheet S, Then, the discharge device D1 increases the absolute value of the charge amount of the laminated toner image (color toner image).

An oscillating voltage having a peak-to-peak voltage of V _PP and a center voltage of _VDC is applied to the discharge member 12, and the discharge member 12 discharges to the toner image on the intermediate transfer belt 4 to charge the toner. Increase the absolute value of the quantity. In this example, since the charging polarity of the toner is negative, the center voltage _VDC of the oscillating voltage applied to the discharging member 12 is negative. Additionally,
The absolute value of the center voltage _VDC is made larger than the absolute value of the charged potential of the laminated toner image. Thus, the absolute value of the charge amount of the laminated toner image can be increased, and the scattering of the toner at the time of the secondary transfer can be suppressed as in the case of the image forming apparatus A1. As described in the description of the image forming apparatus A1, the toner on the intermediate transfer belt 4 is aggregated or melted before the secondary transfer by adjusting the peak-to-peak voltage V _PP of the oscillation voltage. You may.

As described above, in the image forming apparatus A3,
The discharge device D1 facing the intermediate transfer belt 4 causes either toner scattering generated when a toner image is transferred over the toner image already transferred on the intermediate transfer belt 4 or toner scattering generated during the secondary transfer. Can also be suppressed. Accordingly, the image forming apparatus A3 can form a good color toner image on the recording sheet.

In the image forming apparatus A3, similarly to the image forming apparatus A1, the discharging device D1 is disposed at a position facing the photosensitive member 91 and between the developing area and the primary transfer area.
The amount of charge of the toner image on the photoconductor 91 before the primary transfer may be adjusted to suppress toner scattering. (6) FIG. 8 shows a schematic configuration diagram of another example of the image forming apparatus according to the present invention.

The image forming apparatus A4 shown in FIG. 8 is a transfer drum type color image forming apparatus. Image forming apparatus A4
, An eraser lamp 9 is provided around the photoconductor 91.
2. A charging charger 93, a laser device 94, a cyan developing device 95C, a magenta developing device 95M, a yellow developing device 95Y, a black developing device 95K, a transfer drum 5, and a cleaning device 97 are arranged in this order.

The image forming apparatus A4 can form a color toner image on the recording sheet S based on the original image as follows. At the time of image formation, the photosensitive member 91 is driven to rotate clockwise in FIG.
It is driven to rotate counterclockwise. At the time of image formation, the recording sheet S is supplied onto the outer peripheral surface of the transfer drum 5, the recording sheet is carried on the transfer drum 5, and the recording sheet S is rotated together with the transfer drum 5.

First, the image forming apparatus A
In the same manner as in 1, the electrostatic latent image corresponding to the cyan component original image is formed, and this is developed by the cyan developing device 95C using cyan toner. In the present embodiment, the developing device 95C performs development using negatively charged toner. The cyan toner image formed on the photoconductor 91 is transferred onto the recording sheet S carried on the transfer drum 5 by the transfer charger 963. Similarly, magenta, yellow, and black toner images are sequentially formed on the photosensitive member 91, and each time a toner image of each color is formed, the toner image is already transferred onto the recording sheet S carried on the transfer drum 5. And transfer it onto the existing toner image. Developing devices 95M, 95Y and 95K are also developing devices 9
As with 5C, development is performed using negatively charged toner. As a result, a color toner image in which cyan, magenta, yellow, and black toner images are stacked on the recording sheet S carried on the transfer drum 5 is formed. Thereafter, the recording sheet S
Is separated from the transfer drum 5 by a separation charger 964 and transported to the fixing device 98. After the fixing device 98 fixes the toner image on the recording sheet, the recording sheet is discharged out of the image forming apparatus.

In the image forming apparatus A4, a discharge device D1 is disposed at a position facing the outer peripheral surface of the transfer drum 5. More specifically, the discharge unit 1 of the discharge device D1 is disposed at a position facing the recording sheet S carried on the transfer drum 5 during image formation. In FIG. 8, the positioning member of the discharge unit 1 is not shown. The discharge member 12 of the discharge unit 1 is separated from the recording sheet S carried on the transfer drum 5 by a predetermined distance. A roller r5 that is grounded is disposed at a position where the discharge unit 1 faces the transfer drum 5 and on the inner peripheral surface side of the transfer drum 5.

In the image forming apparatus A4, as in the case of the image forming apparatus A3, the scattering of toner generated when a toner image of another color is transferred on the toner image already transferred on the recording sheet S is transferred. In order to suppress, the discharge device D1
Is provided. Also in the image forming apparatus A4, an oscillating voltage is applied to the discharge member 12 to discharge the toner image on the recording sheet S before transferring the next toner image to the toner image transferred on the recording sheet S1. The above problem can be suppressed by discharging the member 12 to lower the absolute value of the charge amount of the toner, for example. Even if the toner on the recording sheet is agglomerated or melted by the discharge from the discharge member 12, the above problem can be suppressed. Therefore, also in the image forming apparatus A4, it is possible to suppress scattering of the toner and form a good color toner image on the recording sheet.

In the image forming apparatus A4, the discharge member 1
2 which is the center voltage of the oscillating voltage applied to _DCAnd / or pea
Voltage V_PPWas described in the description of the image forming apparatus A3.
Depends on the number of the toner image before it is transferred.
You may get. The same effect can be obtained. Image forming device
Also in A4, similarly to the image forming apparatus A1, the photoconductor 9
1 and between the developing device 95K and the transfer area.
A discharge device D1 is also arranged on the photosensitive member 91 before transfer.
Discharges the toner image and suppresses toner scattering
Is also good. (7) FIG. 9 shows still another example of the image forming apparatus according to the present invention.
FIG. 2 shows a schematic configuration diagram of an example.

The image forming apparatus A5 shown in FIG. 9 is a tandem type color image forming apparatus. Image forming apparatus A5
Has four photoconductor units (image forming units) of a cyan photoconductor unit PC, a magenta photoconductor unit PM, a yellow photoconductor unit PY, and a black photoconductor unit PK, and a sheet transport belt 6. The photoconductor units PC, PM, PY, and PK have drum-shaped photoconductors 91C, 91M, 91Y, and 91K, respectively.

Photoconductor 91C of cyan photoconductor unit PC
, An eraser lamp 92C, a charging charger 93C, a laser device 94C, a developing device 95C, a transfer charger 96C, and a cleaning device 97C are arranged. Devices similar to the cyan photoconductor unit PC are sequentially arranged around the photoconductors of the magenta photoconductor unit PM, the yellow photoconductor unit PY, and the black photoconductor unit PK.

The sheet transport belt 6 has rollers r71, r
It is an endless belt wound around 72. At the time of image formation, the recording sheet S is supplied on the outer peripheral surface of the sheet conveying belt 6, and the recording sheet S is carried on the outer peripheral surface of the sheet conveying belt. At the time of image formation, the driving device 6D uses the roller r71.
Is rotated counterclockwise in FIG. 9 so that the recording sheet S carried on the sheet conveying belt 6 is moved to the photosensitive members 91C, 91M,
The sheet is conveyed while sequentially facing 91Y and 91K. Each photoconductor unit forms a toner image based on a document image on the photoconductor, and transfers the toner image onto a recording sheet conveyed by a sheet conveyance device including a sheet conveyance belt 6 and a driving device 6D. it can. A transfer device for transferring a toner image from each photoconductor to a recording sheet includes a sheet conveying belt 6.
Is located on the inner peripheral side of the photoconductor and facing the photoconductor.

The image forming apparatus A5 can form a color toner image on a recording sheet based on a document image as follows. In the cyan photoconductor unit PC, an electrostatic latent image corresponding to a cyan component original image is formed on the photoconductor 91C in the same manner as in the image forming apparatus A1, and the electrostatic latent image is formed by a cyan developing device 95C using cyan toner. develop.
In the present embodiment, the developing device 95C performs development using negatively charged toner. The cyan toner image formed on the photoconductor 91C is transferred onto the recording sheet S conveyed by the sheet conveying belt 6. Also in the magenta photoconductor unit PM, the yellow photoconductor unit PY, and the black photoconductor unit PK, a magenta toner image, a yellow toner image, and a black toner image are formed on the photoconductor in parallel with the cyan photoconductor unit PC. . Photoconductor unit PM, PY, PK
Also, a toner image is formed using negatively charged toner. These magenta toner image, yellow toner image, and black toner image are sequentially transferred so as to be superimposed on the toner image already transferred on the recording sheet S carried on the sheet conveying belt 6. As a result, a color toner image in which cyan, magenta, yellow, and black toner images are stacked on the recording sheet S carried on the sheet conveying belt 6 is formed. Thereafter, the recording sheet S is separated from the sheet conveying belt 6 and is conveyed to the fixing device 98. After fixing is performed by the fixing device 98, the recording sheet is discharged outside the image forming apparatus.

In the image forming apparatus A5, the discharge devices D11 and D1 are located at positions facing the outer peripheral surface of the sheet conveying belt 6.
2, D13 are arranged. Discharge device D11, D1
2 and D13 are substantially the same as the discharge device D1 shown in FIG. Discharge unit 1 of discharge device D11
Are arranged between the cyan photoconductor unit PC and the magenta photoconductor unit PM. The discharge unit 1 of the discharge device D12 is disposed between the magenta photoconductor unit PM and the yellow photoconductor unit PY. Discharge device D1
The third discharge unit 1 is disposed between the yellow photoconductor unit PY and the black photoconductor unit PK. Ground rollers r61, r62, r63 are arranged at positions facing the discharge unit 1 of the discharge devices D11, D12, D13, respectively, on the inner peripheral surface side of the sheet conveying belt 6.

In the image forming apparatus A5, as in the case of the image forming apparatus A3, the scattering of toner that occurs when a toner image of another color is transferred on the recording sheet S when the toner image is transferred is superimposed on the already transferred toner image. In order to suppress, the discharge device D1
1, D12 and D13 are provided. Image forming apparatus A
Also in 5, an oscillating voltage is applied to the discharge member 12 to discharge the toner image on the recording sheet S before transferring the next toner image over the toner image transferred onto the recording sheet S. Then, the absolute value of the charge amount of the toner on the recording sheet S is reduced. Before transferring the next magenta toner image over the cyan toner image transferred onto the recording sheet S, the discharging device D
At 11, the charge amount absolute value of the cyan toner image is reduced. Similarly, before transferring the yellow toner image over the toner image already transferred on the recording sheet S, the discharging device D12
To lower the absolute value of the charge amount of the toner on the recording sheet. Before the black toner image is transferred over the toner image already transferred on the recording sheet S, the absolute value of the charge amount of the toner on the recording sheet is reduced by the discharging device D13. Thus, even in the image forming apparatus A5, the above-described problem can be suppressed, and a good color toner image can be formed on the recording sheet accordingly.

Recording is performed by the discharge devices D11, D12, and D13.
The next toner image is superimposed on the toner image transferred on the sheet S.
Before transferring the toner, discharge to the toner image on the recording sheet S is performed.
Even if the toner on the recording sheet S is aggregated or melted
Good. Even in this case, the scattering of toner is suppressed.
be able to. Also in the image forming apparatus A5, the discharge member
12 which is the center voltage of the oscillating voltage applied to _DCAnd / or
Peak-to-peak voltage V_PPIs described in the description of the image forming apparatus A3.
As before, depending on the number of the toner image before transferring
You may change it. The same effect can be obtained.

In the image forming apparatus A5, similarly to the image forming apparatus A1, the discharge device D1 is disposed at a position facing the photoreceptor of each photoreceptor unit and between the developing area and the transfer area. Discharge member 12 to toner image on previous photoreceptor
May be performed to suppress the scattering of the toner. (8) FIG. 10 is a schematic configuration diagram of still another example of the image forming apparatus according to the present invention.

The image forming apparatus A6 shown in FIG. 10 is an electrophotographic monochrome image forming apparatus. Image forming apparatus A
6 is the image forming apparatus A of FIG. 1 except for the following.
It is substantially the same as 1. In the image forming apparatus A6, a discharge device D1 is disposed upstream of the fixing device 98 instead of the position facing the photoconductor 91. A grounded sheet guide 991 is arranged at a position facing the discharge unit 1 of the discharge device D1. In FIG. 10, the positioning member of the discharge unit 1 is not shown.
The discharge member 12 of the discharge unit 1 includes a sheet guide 991
And is separated from the recording sheet S conveyed toward the fixing device 98 by a predetermined distance.

In the image forming apparatus A6, a toner image based on a document image is formed on the photosensitive member 91 in the same manner as the image forming apparatus A1 in FIG. In the image forming apparatus A6, the developing device 95 performs development using positively charged toner. Thereafter, the recording sheet S is conveyed to the fixing device 98 by a sheet conveying device including a sheet guide 991 and a sheet conveying belt 992,
Fixing is performed.

The fixing device 98 has two fixing rollers 981,
982, and the toner image is fixed by passing the recording sheet between these fixing rollers. During fixing, the fixing roller 981 is heated to a predetermined fixing temperature by a heating device (not shown). The fixing roller 982 presses the fixing roller 981 with a predetermined pressing force. By passing the recording sheet holding the unfixed toner between the fixing rollers 981 and 982, heat and pressure are applied to the toner to fix the toner on the recording sheet.

In the image forming apparatus A6, before the toner image transferred onto the recording sheet S is fixed by the fixing device 98, an oscillating voltage is applied to the discharging member 12 of the discharging device D1, so that the discharging member 12 The toner image on the recording sheet is discharged by discharging the toner image on the recording sheet. This suppresses the following problems. In the fixing device 98, the fixing rollers 981 and 982 may be charged due to the friction between the fixing rollers and the recording sheet. When the fixing roller 981 on the side in contact with the toner image on the recording sheet is charged to a polarity opposite to the charging polarity of the toner, when the recording sheet enters the nip portion between the fixing rollers 981 and 982, the toner on the recording sheet Is transferred to the fixing roller 981, and satisfactory fixing cannot be performed. In this example, the fixing roller 981 that contacts the toner image on the recording sheet at the time of fixing is a roller coated with polytetrafluoroethylene, and the fixing roller 981 is negatively charged. As described above, the charging polarity of the toner carried on the recording sheet S is positive in this example, so that when the recording sheet enters the fixing roller nip portion, the toner image on the recording sheet is fixed to the fixing roller 981. Easy to transfer to.

In the image forming apparatus A6, the discharging device D
In 1, the toner image on the recording sheet S is charged to the same polarity as the charging polarity (in this example, negative polarity) of the fixing roller 981 before fixing, so that the offset of the toner to the fixing roller 981 can be suppressed. Thus, good fixing can be performed. In this example, since the frictional charging polarity of the fixing roller 981 is negative, the polarity of the center voltage _VDC of the oscillating voltage applied to the discharge member 12 is negative, and the positively charged toner on the recording sheet is negatively charged. I do.

In the image forming apparatus A6, an experiment was conducted in which the peak-to-peak voltage V _pp and the center voltage V _pp of the oscillating voltage applied to the discharge member were changed to examine the occurrence of toner offset to the fixing roller 981. The results are shown in Table 2 below.

[0104]

[Table 2]

In Table 2, “○” indicates that no offset of the toner to the fixing roller occurred and the offset of the toner could be prevented. “△” indicates that the toner offset was small and the toner offset could be suppressed. “×” indicates that there was a toner offset. When the peak-to-peak voltage V _PP was 3.5 kV or more, it was found by microscopic observation that the toner before fixing was aggregated on the recording sheet.

When the peak-to-peak voltage V _PP was 4.5 kV or more, the toner before fixing on the recording sheet was melted. From these results, the oscillating voltage was applied to the discharge member, and the peak-to-peak voltage V _PP and the center voltage V _DC of the oscillating voltage were applied.
It can be seen that by adjusting the value, the transfer of the toner on the recording sheet to the fixing roller 981 can be suppressed. By applying an oscillating voltage to the discharge member and melting the toner before fixing,
It can be seen that the center voltage _VDC may be 0 [V] or may be either positive or negative. When charging the toner or melting the toner without melting the toner on the recording sheet, the polarity of the center voltage _VDC of the oscillating voltage applied to the discharge member is determined by the charging of the fixing roller 981 that comes into contact with the toner. It can be seen that the same polarity as the polarity (in this example, negative polarity) is better, and that the absolute value of the center voltage _VDC is larger.

In each of the image forming apparatuses A1 to A5, a discharge device is also arranged upstream of the fixing device 98 to discharge the toner on the recording sheet in the same manner as described above to transfer the toner to the fixing roller. It may be suppressed. (9) In any of the image forming apparatuses A1 to A6,
11 and 1 in place of the discharge unit 1 shown in FIG.
2 may be employed. FIG.
1, a discharge unit 3 is provided instead of the discharge unit 1 in the image forming apparatus A1 of FIG. 1, and the discharge unit 3 faces the photoconductor 91.

The discharge unit 3 includes the electrode 31, the discharge member 3
2 and positioning members 331 and 332. The electrode 31 has a roller shape and extends in the rotation axis direction of the photoconductor 91. The electrode 31 is made of a conductive material, and is connected to the voltage applying device 2. The discharge member 32 is a film that covers the outer peripheral surface of the electrode 31, and extends in the rotation axis direction of the photoconductor 91. The discharge member 32 is adhered to the electrode 31 by a conductive adhesive. The discharge member 32 has a cylindrical shape. Since the discharge member 32 has such a shape,
Similarly to the discharge member 12 of the discharge device D1, the distance from the surface 321 of the discharge member 32 facing the photoconductor 91 to the outer peripheral surface 911 of the photoconductor increases as it goes downstream from the discharge region. The thickness and material of the discharge member (film) 32 are the same as those of the discharge member 12.

The positioning members 331 and 332 are insulating films wound around both ends of the discharge member 32 in the rotation axis direction of the photoconductor. Positioning members 331, 332
Are bonded to the discharge member 32 with an adhesive. The positioning members 331 and 332 are in contact with the outer peripheral surface 911 of the photoconductor, similarly to the positioning members 131 and 132 of the transfer device D1. By the positioning members 331 and 332, the discharge member peripheral surface 321 is separated from the photosensitive member peripheral surface 911 by a predetermined distance.

In the discharge device D3, the discharge unit 3 including the electrode 31, the discharge member 32, and the positioning members 331 and 332 is rotatably supported. Discharge device D3
In, the discharge unit 3 rotates following the rotation of the photoconductor 91. Even when the discharge unit 3 is used, scattering of toner and the like can be suppressed as in the case where the discharge unit 1 is used.

[0111]

As described above, the present invention can provide an image forming apparatus capable of suppressing toner scattering and forming a good image. To give a specific example, the present invention can suppress toner scattering when a toner image formed on a toner image carrier such as a photoreceptor is transferred to a transfer receiving body, and can perform good image formation accordingly. An image forming apparatus that can be provided.

The present invention is also directed to an image forming apparatus in which a toner image is sequentially transferred onto a transfer target such as an intermediate transfer member or a recording sheet, and the image forming apparatus is provided with a toner image which has already been transferred onto the transfer target. Thus, it is possible to provide an image forming apparatus capable of suppressing scattering of toner when a next toner image is transferred, and performing good image formation accordingly. Further, the present invention is an image forming apparatus in which a toner image transferred onto a recording sheet is fixed by a fixing device, which can suppress scattering of toner generated at the time of fixing and toner offset to a fixing member. An image forming apparatus capable of forming a good image can be provided.

Further, the present invention can provide a discharge device which can suppress toner scattering when used in an image forming apparatus.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an example of an image forming apparatus of the present invention.

FIG. 2 is a schematic perspective view of a discharge unit of a discharge device provided in the image forming apparatus of FIG.

FIG. 3 is a schematic side view of the discharge unit of FIG.

FIG. 4 is an enlarged view of a portion around a discharge unit of the image forming apparatus of FIG. 1;

FIG. 5 is a diagram illustrating an example of an oscillating voltage applied to a discharge member.

FIG. 6 is a schematic configuration diagram of another example of the image forming apparatus of the present invention.

FIG. 7 is a schematic configuration diagram of still another example of the image forming apparatus of the present invention.

FIG. 8 is a schematic configuration diagram of still another example of the image forming apparatus of the present invention.

FIG. 9 is a schematic configuration diagram of still another example of the image forming apparatus of the present invention.

FIG. 10 is a schematic configuration diagram of still another example of the image forming apparatus of the present invention.

FIG. 11 is a view showing still another example of the discharge unit.

FIG. 12 is a schematic perspective view of the discharge unit of FIG.

[Explanation of symbols]

 A1 to A6 Image forming device D1, D2, D3 Discharge device 1, 3 Discharge unit 11, 31 Electrode 12, 32, 14 Discharge member 131, 132, 331, 332 Positioning member 2 Voltage application device 21 DC power supply 22 AC power supply 4 Intermediate Transfer belt (intermediate transfer member) 5 Transfer drum (sheet carrier) 6 Sheet transport belt 6D Sheet transport belt driving device 91, 91C, 91M, 91Y, 91K Photoconductor 911 Photoconductor outer peripheral surface 92 Eraser lamp 93 Charger 94 Laser device 95, 95C, 95M, 95Y, 95K Developing device 951 Developing roller 961 Transfer device (primary transfer device) 961r Transfer roller (primary transfer roller) 961s Transfer power supply (primary transfer power source) 962 Secondary transfer device 962r Secondary transfer roller 962s Second Next transfer power supply 963 Transfer Yaja 964 separation charger 96C transfer charger 97 cleaning device 98 fixing device 981, 982 a fixing roller (fixing member) 991 sheet guide S recording sheet

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) 2H027 EA18 EB04 ED15 ED24 ED25 ED26 2H032 AA05 AA15 BA01 BA02 BA05 BA09 BA16 BA21 BA23 BA26 CA02 2H033 BA02 BA09 BA13 BB01 BB12 BB17 BB28 BB33 BB34 2DB0DB08 AD06 AD06

Claims (18)

[Claims] 1. An image forming apparatus for forming a toner image based on a document image on a recording sheet, comprising: a discharge member facing a toner carrying surface of the toner image carrier at a predetermined distance from the toner carrying surface; To discharge from the discharge member toward the toner on the toner image carrier,
A discharge device having a voltage application device for applying a predetermined voltage to the discharge member, wherein the voltage application device performs a discharge from the discharge member to the toner on the toner image carrier when a peak-to-peak voltage V is applied. An image forming apparatus, wherein an oscillating voltage having a predetermined waveform that is twice or more a discharge starting voltage when the _PP causes the discharge member to discharge to the toner on the toner image carrier is applied to the discharge member. 2. An image forming apparatus, wherein the toner carrying surface of the toner image carrier moves in a predetermined direction with respect to the discharge member, and the surface of the discharge member facing the toner carrying surface is in the toner carrying surface moving direction. 2. The image forming apparatus according to claim 1, wherein the image forming apparatus has an area in which the distance to the toner carrying surface gradually increases toward the downstream side of the image forming apparatus. 3. The image forming apparatus according to claim 1, wherein the voltage applying device applies an oscillating voltage to the discharge member to soften, aggregate, or melt the toner on the toner image carrier. 4. An electrostatic latent image carrier on which an electrostatic latent image based on a document image is formed, and a developing device for developing the electrostatic latent image on the electrostatic latent image carrier using toner. A transfer device for transferring a toner image formed on the electrostatic latent image carrier to a predetermined transfer receiving body, wherein the toner image carrier facing a discharge member of the discharge device is the toner image carrier. An electrostatic latent image carrier, wherein before the toner image formed on the electrostatic latent image carrier by the developing device is transferred to the transfer object by the transfer device, the discharging device The image forming apparatus according to claim 1, wherein discharge to the toner on the latent image carrier is performed. 5. An electrostatic latent image carrier on which an electrostatic latent image based on a document image is formed, and a developing device for developing the electrostatic latent image on the electrostatic latent image carrier using a predetermined color toner A primary transfer device for transferring the toner image formed on the electrostatic latent image carrier to an intermediate transfer member, and transferring the toner image transferred on the intermediate transfer member to a recording sheet The toner image carrier facing the discharge member of the discharge device is the intermediate transfer member, and the discharge device discharges to the toner on the intermediate transfer member. The image forming apparatus according to claim 1. 6. The discharging device according to claim 1, wherein the discharging device discharges the toner already transferred to the intermediate transfer member before a next toner image is transferred onto the toner image already transferred to the intermediate transfer member. The image forming apparatus according to claim 5, wherein: 7. A discharge device according to claim 1, wherein said discharging device discharges the toner already transferred to said intermediate transfer member by a peak of an oscillating voltage applied to said discharging member depending on a number of toner images to be transferred. 7. The image forming apparatus according to claim 6, wherein the intermediate voltage V _{PP and} / or the center voltage V _DC of the oscillating voltage is changed. 8. The discharging device according to claim 1, wherein the toner image on the intermediate transfer member is transferred to a recording sheet by the secondary transfer device.
8. A discharge to the toner on the intermediate transfer member is performed.
An image forming apparatus according to any one of the above. 9. An electrostatic latent image carrier on which an electrostatic latent image based on a document image is formed, and an electrostatic latent image on the electrostatic latent image carrier for developing the electrostatic latent image using toner of a predetermined color. With multiple developing devices,
A transfer device for transferring a toner image formed on the electrostatic latent image carrier onto a recording sheet carried on a sheet carrier, wherein the toner image facing a discharge member of the discharge device is provided. 4. The image forming apparatus according to claim 1, wherein the carrier is a recording sheet carried on the sheet carrier during image formation, and the discharging device discharges toner on the recording sheet carried on the sheet carrier. An image forming apparatus according to claim 1. 10. The discharging device according to claim 1, wherein the discharging device transfers the toner image onto the recording sheet before the next toner image is transferred on the recording sheet carried on the sheet carrier. The image forming apparatus according to claim 9, wherein the discharging is performed to the used toner. 11. The discharging device according to claim 1, wherein when discharging to the toner already transferred onto the recording sheet carried on the sheet carrying member, the discharging member depends on how many toner images have been transferred. The image forming apparatus according to claim 10, wherein the peak-to-peak voltage V _PP of the oscillating voltage applied to the image forming apparatus and / or the center voltage _VDC of the oscillating voltage is changed. 12. A plurality of image forming units each capable of transferring a toner image of a predetermined color based on a document image onto a recording sheet, and a unit for conveying the recording sheet while sequentially facing each of the image forming units. A sheet conveying device, wherein the toner image bearing member facing the discharging member of the discharging device is a recording sheet conveyed by the sheet conveying device at the time of image formation, and the discharging device is a sheet conveying device. The image forming apparatus according to claim 1, wherein the image forming apparatus discharges the toner on the conveyed recording sheet. 13. The discharging device according to claim 1, wherein said discharging device transfers the toner image onto the recording sheet before the next toner image is transferred onto the recording sheet conveyed by the sheet conveying device before the next toner image is transferred. And discharging the discharged toner.
3. The image forming apparatus according to 2. 14. The discharging device according to claim 1, wherein the discharging device discharges the toner already transferred onto the recording sheet conveyed by the sheet conveying device, depending on how many toner images have been transferred. _14. The image forming apparatus according to claim 13, wherein the peak-to-peak voltage V _{PP of the} oscillating voltage and / or the center voltage _VDC of the oscillating voltage is changed. 15. An image forming apparatus for transferring a toner image based on a document image onto a recording sheet, and a fixing device for fixing the toner image transferred onto the recording sheet to the recording sheet, the discharge device comprising: The toner image carrier facing the discharge member of the device is a recording sheet onto which the toner image has been transferred by the image forming device, and before the fixing device fixes the toner image on the recording sheet, the discharge device is 4. The image forming apparatus according to claim 1, wherein discharge to the toner on the recording sheet is performed. 16. The fixing device has two fixing members facing each other, the fixing device performs fixing by passing a recording sheet through a nip portion of the fixing member, and the discharging member includes: 16. The image forming apparatus according to claim 15, wherein a center voltage _VDC is applied with an oscillating voltage having the same polarity as a triboelectric charging polarity of a fixing member of the two fixing members that is in contact with the toner image on the recording sheet. . 17. The image forming apparatus according to claim 1, wherein said voltage applying device applies a rectangular wave-shaped vibration voltage to said discharge member. 18. A discharge device for discharging to a toner carried on a toner image carrier in an image forming apparatus, wherein the discharge device is separated from the toner carrying surface of the toner image carrier by a predetermined distance and faces the toner carrying surface. A discharge member, and a voltage application device for applying a predetermined voltage to the discharge member to cause discharge from the discharge member toward the toner on the toner image carrier. discharge device voltage V _PP and applying to the discharge member an oscillating voltage of a is predetermined waveform at least twice the discharge starting voltage when discharging from the discharge member to the toner on the toner image carrier.