JP2001075448A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device mounted with cleaning system capable of effectively recovering toner in reverse polarity by merely performing simple system control, even in the case when residual toner in reverse polarity is generated at the image forming job. SOLUTION: This is the image forming device provided with a photoreceptor 10, a contact system charging device 11, an exposing device 12, a developing device 13, and a contact system transferring device. This device is also provided with a cleaning device 71 on a transfer body constituting the contact system transferring device so as to form potential gradient between a transfer body provided for a cleaning mode of the image forming job and the contact system charging device to collect the residual toner remaining on the contact contact system charging device 11, the photoreceptor, and the contact system transfer device, a transfer body provided with a cleaning device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus employing an image forming system such as an electrophotographic recording system, an electrostatic recording system, an ionography, a magnetic recording system, and the like. The latent image is developed with toner to form a toner image, and the toner image is transferred onto a recording sheet such as paper or an OHP sheet, and then the toner image is fixed on the recording sheet and recorded. The present invention relates to an image forming apparatus that forms an image.

[0002]

2. Description of the Related Art Generally, in an image forming apparatus, after a toner image formed on an image carrier is transferred onto a recording sheet, residual toner remaining on the image carrier is collected by a cleaning device. 2. Description of the Related Art Toner is temporarily accumulated in a collecting container, and is discarded when the amount of collected toner reaches a certain amount.

In a full-color image forming apparatus, image data is received from a host device such as a personal computer or a workstation, and the image data is separated into four colors of yellow, magenta, cyan, and black based on the image data. A toner image of each color is formed on the image carrier based on the color-separated image information, and the toner images of each color are superimposed on an intermediate transfer body such as an intermediate transfer roll or an intermediate transfer belt, and then collectively on a recording sheet. A full-color image is obtained by transfer, but in this case as well, the residual toner remaining on the image carrier and the intermediate transfer body is collected by a cleaning device, and the collected toner is temporarily stored in a collection container. The toner is accumulated and discarded when the amount of collected toner reaches a certain amount.

In such an image forming apparatus, the cleaning step for removing residual toner remaining on the image carrier and the intermediate transfer member is performed by removing the residual toner as it is in a recorded image such as ghosts, fogging, etc. This is an extremely important step because it causes color unevenness due to the above-mentioned factors.

[0005] However, in recent years, as the problem of environmental protection has come to the fore, the amount of residual toner collected and discarded in this manner is required to be reduced as much as possible. It is required to reuse the remaining toner.

[0006] Further, the problem of the reduction of the amount of waste for environmental protection and the reuse of waste is not limited to the residual toner collected from the image carrier or the intermediate transfer member. However, when a cleaning device is attached to an image carrier or an intermediate transfer member, the cleaning blade or cleaning brush of the cleaning device slides on the surface of the image carrier or the intermediate transfer member. This causes wear, which is an obstacle in extending the life of the image carrier and the intermediate transfer body.

Therefore, various proposals have conventionally been made from such a viewpoint. For example, JP-A-8-314,2
In Japanese Patent Application Publication No. 31-301, an image forming apparatus that performs a primary transfer of a toner image formed on an image carrier onto an intermediate transfer body and then secondary-transfers the toner image on the intermediate transfer body onto a recording sheet is used. A voltage having a polarity opposite to that of the residual toner remaining on the intermediate transfer member at the time of the secondary transfer is applied to the transfer member, whereby the residual toner on the intermediate transfer member is moved to a transfer roll to be removed. It is described that the cleaning by the cleaning is unnecessary and the wear is suppressed.

Japanese Patent Application Laid-Open No. 9-197,750 discloses that after a toner image formed on an image carrier is primarily transferred onto an intermediate transfer member, the toner image on the intermediate transfer member is secondarily transferred onto a recording sheet. In the image forming apparatus for transferring, a toner collecting member for temporarily collecting residual toner is disposed on the intermediate transfer body, and at the start of secondary transfer, the toner collecting member is brought into contact with the intermediate transfer body to collect residual toner, After the completion of the secondary transfer, the residual toner collected by the toner collecting member is moved onto the intermediate transfer member, and the toner collecting member is further separated from the intermediate transfer member to move the residual toner from the intermediate transfer member onto the image carrier. It is described that the residual toner moved onto the image carrier is collected by a cleaning device attached to the image carrier.

Further, Japanese Patent Application Laid-Open No. 10-161,425 discloses that at least two kinds of different fine particles having a smaller particle diameter than the toner and having a charge polarity opposite to the toner are added to the toner. Causes at least one kind of fine particles to remain on the image carrier, and in the developing step, a toner image is formed on the image carrier via the fine particles, thereby reducing the adhesive force between the toner image and the image carrier. It is described that the transfer efficiency of the toner image is remarkably improved, and a recorded image without ghost or fog is formed without using a cleaning device.

However, in the methods described in JP-A-8-314,231 and JP-A-9-197,750, a cleaning device around the image carrier cannot be omitted, and
There is also a problem that the amount of residual toner collected from the image carrier and the intermediate transfer member cannot be reduced.

The present inventors have constructed a color image forming apparatus as shown in FIG. 19, and have significantly improved the transfer efficiency of a toner image as disclosed in Japanese Patent Application Laid-Open No. 10-161,425. A method of reducing the amount of generated toner as much as possible and omitting the cleaning device around the image carrier is described in, for example, Japanese Patent Application Laid-Open No. 10-78,686. An attempt was made to apply it to a tandem type full color image forming apparatus.

That is, in the tandem type full-color image forming apparatus shown in FIG. 19, the two image carriers 10 and 20 for yellow (Y) and magenta (M) contact one of the first intermediate transfer rolls 51. The other two image carriers 30 and 40 for cyan (C) and black (K) are in contact with the other first intermediate transfer roll 52, and the pair of first intermediate transfer rolls Numerals 51 and 52 contact the second intermediate transfer roll 53, and the four image carriers 10, 20, 30, and 40 shown here are configured to have a common tangent. These four image carriers 10, 20, 30, and 40 are respectively provided with charging rolls (contact type charging devices) 11, 21, 31, 41, exposure devices 12, 22, 32, 42, and The developing devices 13, 23, 33, and 43 are arranged in the same positional relationship with each other, and components are shared for each type of device. Each of the developing devices 13, 23, 33, and 43 conveys the developing roll 131, the developer amount regulating member 132, the developer conveying member 133, and the developer.
Further, an auger 134 for stirring is provided.

Therefore, in this tandem type full-color image forming apparatus, each single-color toner image formed by the two image carriers 10 and 20 is transferred to the first intermediate transfer roll 51 and then to the second intermediate transfer roll. Each single-color toner image formed on the two image carriers 30 and 40 is transferred to a first intermediate transfer roll 52, and then transferred to a second intermediate transfer roll 52.
The sheet (recording sheet) transferred onto the second intermediate transfer roll 53, superimposed on the second intermediate transfer roll 53, and then transported by the transport roll 91 to the final transfer roll 61 in contact with the second intermediate transfer roll 53. ) The toner image transferred collectively onto the sheet P and transferred onto the sheet P is fixed by the fixing device 70. In this method, a plurality of image carriers 1 are used.
0, 20, 30, 40, charging rolls 11, 21, 31, 41, exposure device 1
2, 22, 32, 42, developing devices 13, 23, 33, 43, first intermediate transfer rolls 51, 52, etc. There is an advantage that highly accurate alignment of an image is enabled.

However, each image carrier 10, 20, 30, 40
The single-color toner image formed on the image carrier 30 is transferred between the image carrier 30 and the first intermediate transfer roll 52 by the first Similarly, a total of three times between the intermediate transfer roll 52 and the second intermediate transfer roll 53 and between the second intermediate transfer roll 53 and the sheet P are formed by the image carriers 10 and 40, respectively. The transfer electric field is applied at least three times and at most five times, such as four times for the single-color toner image and five times for each single-color toner image formed on the image carrier 20.

For this reason, the toner forming the toner image is
Due to the Paschen discharge before and after the transfer nip when receiving the transfer electric field and the charge injection in the transfer nip, the toner is charged to the opposite polarity, albeit slightly, and the opposite polarity toner charged to the opposite polarity is opposite to the positive polarity toner during image formation. , And eventually accumulates on the image carrier or a contact-type charger in contact with the image carrier. In particular, when a contact-type charger is used, the contact-type charger adsorbs the opposite polarity residual toner that has flowed backward to the image carrier, causing problems such as uneven charging due to long-term use. It causes color unevenness.

Therefore, in the method of remarkably improving the transfer efficiency of the toner image and omitting the cleaning device around the image carrier, the amount of residual toner generated can be reduced as much as possible. Although it is possible to extend the life of the image carrier and the like by omitting the apparatus, there is another problem that it is difficult to prevent the occurrence of an image defect when the opposite polarity residual toner is generated.

[0017]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a simple system control system which can generate reverse polarity residual toner in an image forming apparatus. It is an object of the present invention to provide an image forming apparatus equipped with a cleaning system capable of effectively collecting the toner only by performing the cleaning.

Another object of the present invention is to provide an image forming apparatus including an image carrier, a contact type charging device, an exposure device, a developing device, and a contact type transfer device, which constitutes one of the contact type transfer devices. A cleaning device is attached to the transfer member, and the positive residual toner and the reverse polarity residual toner that are inevitably generated in the image forming apparatus are collected in the transfer device with the cleaning device, and the residual toner can be collectively collected by the cleaning device. Accordingly, an object of the present invention is to provide an image forming apparatus capable of extending the life of an image carrier by omitting a cleaning device around the image carrier.

Still another object of the present invention is to provide an image forming apparatus including an image carrier, a contact type charging device, an exposing device, a developing device, an intermediate transfer member, and a final transfer member. And a temporary holding member is attached to the intermediate transfer body to temporarily temporarily hold a part or all of the positive polarity residual toner and / or the reverse polarity residual toner which are inevitably generated during image formation by the image forming apparatus. The image forming apparatus then collects the remaining toner in a final transfer member provided with the cleaning device when the image forming apparatus is in a cleaning mode, and collects the residual toner by the cleaning device. By eliminating the cleaning device around the body, the life of the image carrier can be extended, and the number of required cleaning modes can be reduced to form a continuous image. And to provide a number of output sheets per unit of time the image forming apparatus capable of preventing a decrease in.

Still another object of the present invention is to provide an image forming apparatus having an image carrier, a charging device, an exposing device, a developing device, an intermediate transfer member, and a final transfer member, wherein a temporary holding member is provided on the intermediate transfer member. Attaching and attaching a cleaning device to the final transfer body, temporarily or temporarily holding a part or all of the residual toner of the positive polarity or the opposite polarity which is inevitably generated at the time of image formation of the image forming apparatus by a temporary holding member, In the cleaning mode of the image forming apparatus, the cleaning device is finally collected on a final transfer member provided with the cleaning device, and the residual toner can be collectively collected by the cleaning device. It is an object of the present invention to provide an image forming apparatus capable of preventing a decrease in the number of output sheets per unit time during continuous image formation by reducing the number of images.

[0021]

That is, a first aspect of the present invention provides an image carrier, a contact-type charging device that contacts and charges the image carrier, and a latent image formed on the surface of the charged image carrier. An exposure device for forming, a developing device for developing a latent image formed on the surface of the image carrier to form a toner image, and at least one transfer body, the surface of which is in contact with the image carrier; And a contact transfer device for transferring the toner image formed on the recording sheet onto a recording sheet. A cleaning device is attached to one transfer body constituting the contact transfer device. In the cleaning mode, a potential gradient is formed between the transfer member with the cleaning device provided with the cleaning device and the contact type charging device, and the contact type charging device, the image carrier, and the contact type transfer device are formed. Remains in Collected residual toner in the cleaning device with the transfer member, and recovered collectively residual toner collected to the cleaning device with transfer member by the cleaning device, an image forming apparatus.

Further, a second invention of the present application provides an image carrier,
A contact-type charging device that contacts and charges the image carrier;
An exposure device for forming a latent image on the charged image carrier surface, a developing device for developing the latent image formed on the image carrier surface to form a toner image, and an image carrier in contact with the image carrier An image forming apparatus comprising: an intermediate transfer member onto which a toner image formed on a surface is transferred; and a final transfer member that contacts the intermediate transfer member to transfer a toner image on the surface of the intermediate transfer member onto a recording sheet. A cleaning device is attached to the final transfer member, and a temporary holding member is attached to the intermediate transfer member. When the image is formed by the image forming apparatus, the temporary holding member removes the residual toner of positive polarity and / or reverse polarity. Part or all of the contact type charging device, the image carrier, the intermediate transfer member, the temporary holding member, and the final transfer member during the cleaning mode of the image forming apparatus. , Held by the temporary holding member Residual toner including collected residual residual toner on the final transfer body, to collect the remaining toner collected on the final transfer body in the cleaning apparatus, an image forming apparatus.

Further, the third invention of the present application is directed to an image carrier,
A charging device for charging the surface of the image carrier, an exposure device for forming a latent image on the surface of the charged image carrier, and a developing device for developing a latent image formed on the surface of the image carrier to form a toner image And an intermediate transfer member on which the toner image formed on the surface of the image carrier is transferred in contact with the image carrier, and the toner image on the surface of the intermediate transfer member is transferred onto the recording sheet by contacting the intermediate transfer member And a temporary holding member attached to the intermediate transfer member, and a cleaning device attached to the final transfer member, wherein the temporary holding member is provided when the image forming apparatus forms an image. With positive polarity and / or
Or, temporarily hold a part or all of the remaining toner of the opposite polarity, and in the cleaning mode of the image forming apparatus, form a potential gradient between the final transfer body, the intermediate transfer body, and the temporary holding member, In an image forming apparatus, the residual toner including the residual toner temporarily retained by the temporary retaining member is collected on a final transfer body, and the residual toner collected on the final transfer body is collected by the cleaning device. is there.

[First Invention] In the first invention of the present application, the configurations of the image carrier and the contact transfer device are not particularly limited, but typically have the following configurations. That is, the image carrier is composed of one image carrier, and the contact-type transfer device is composed of the final transfer body that is the only transfer body that comes into contact with the image carrier. A first type in which the toner image formed on the image carrier is transferred onto the recording sheet while the recording sheet passes between them,

The image carrier is composed of one image carrier, and the contact-type transfer device is composed of an intermediate transfer member that contacts the image carrier and a final transfer member that contacts the intermediate transfer member. A second type in which the toner image transferred from the image carrier to the intermediate transfer body is transferred onto the recording sheet while the recording sheet passes between the intermediate transfer body and the final transfer body; An intermediate transfer member, which includes four image carriers for cyan, magenta, yellow, and black, and a contact transfer device contacts the four image carriers, and a final transfer member that contacts the intermediate transfer member And a third image in which the toner image transferred from the image carrier to the intermediate transfer member is transferred onto the recording sheet while the recording sheet passes between the intermediate transfer member and the final transfer member. Type,

The image carrier is composed of four image carriers for cyan, magenta, yellow, and black, and the contact-type transfer device has two of these four image carriers.
A pair of first intermediate transfer members in contact with one image carrier, a second intermediate transfer member in contact with the pair of first intermediate transfer members, and a final transfer member in contact with the second intermediate transfer member Is transferred from the image carrier to the second intermediate transfer member via the first intermediate transfer member while the recording sheet passes between the second intermediate transfer member and the final transfer member. And a fourth type in which the transferred toner image is transferred onto a recording sheet.

In the four types of the image carrier and the contact type transfer device, the first and second types have the number of developing devices attached to the image carrier, the type of the transfer member used, That is, depending on whether a roll-type transfer roll or a belt-type transfer belt is used, the image forming apparatus can be configured as a black-and-white image forming apparatus, or a multi-color image such as a two-color image such as red and black. And a full-color image forming apparatus including four developing devices for cyan, magenta, yellow, and black.

It is possible to appropriately select which transfer member constituting the contact transfer device is to be provided with the cleaning device in consideration of factors such as the transfer member structure and the installation space of the contact transfer device. In order to simplify the voltage control for each member, the downstream side in the moving direction of the toner image in the transfer step of the contact type transfer device is preferable. For example, in the configuration of the image carrier and the contact type transfer device, When the contact transfer device is composed of an intermediate transfer member and a final transfer member as in the case of the type, the contact transfer device is preferably the final transfer member. When a pair of the first intermediate transfer body, the second intermediate transfer body, and the final transfer body, the second intermediate transfer body or the final transfer body is good, more preferably the final transfer body It is.

In the first invention, the means for forming a potential gradient between the transfer member with the cleaning device and the contact type charging device includes a contact type charging device, an image carrier, and a contact type transfer device. The transfer member constituting the contact-type charging device, the image carrier, and the contact-type transfer device so that residual toner remaining on the transfer member other than the transfer member with the cleaning device can be collected on the transfer member with the cleaning device. What is necessary is just to be able to give a predetermined electric potential to.

As the potential gradient applying means, specifically, when the configuration of the image bearing member and the contact type transfer device is the first type, a voltage is applied to the contact type charging device and the final transfer member. It is a means to do.

In the case where the structure of the image carrier and the contact type transfer device are the above-described second and third types, the case where the transfer type with the cleaning device is the final transfer type is the same as the case of the first type. As with, contact type charging device, intermediate transfer body,
And a means for applying a voltage to the final transfer body, and applying a voltage to the final transfer body and electrically floating an intermediate transfer body between the image transfer body and the final transfer body. And a voltage application means for forming a potential gradient between the relationship between the resistance value of the image carrier and the voltage applied to the contact-type charging device. When the transfer member with the cleaning device is an intermediate transfer member, a means for applying a voltage to the contact-type charging device, the intermediate transfer member, and the final transfer member can be applied.

Further, when the structure of the image carrier and the contact type transfer device is the fourth type, the transfer member with the cleaning device is used as the final transfer member, Similarly to the above, a means for applying a voltage to each contact-type charging device, each first intermediate transfer member, the second intermediate transfer member, and the final transfer member can be applied. Electrically floating the first intermediate transfer member and the second intermediate transfer member between the image transfer member and the final transfer member, the second intermediate transfer member, the first intermediate transfer member, and the image. Means for forming a potential gradient between the resistance value of the carrier and the voltage applied to the contact type charging device can be applied. When the transfer member with the cleaning device is used as the second intermediate transfer member, a voltage is applied to each contact-type charging device, each of the first intermediate transfer member, the second intermediate transfer member, and the final transfer member. In addition to applying means, a voltage is applied to the second intermediate transfer member, and each of the first intermediate transfer members located between the second intermediate transfer member and the grounded image carrier is electrically floated. A potential gradient is formed between the first intermediate transfer member and the image carrier in relation to the resistance value of the first intermediate transfer member and the individual voltage applied to the second intermediate transfer member and the final transfer member. Means can be applied.

Here, the means for applying a voltage is as follows.
In the cleaning mode in the control system of the image forming apparatus, the power supply connected to supply a voltage for each purpose to the contact type charging device and the transfer body constituting the contact type transfer device is used as it is. A necessary voltage may be supplied, and a dedicated power supply for supplying a voltage may be provided separately from the power supply.

Means for applying a voltage and electrically floating to use the relationship of resistance values include, for example, a transfer member constituting an image carrier or a contact transfer device (a transfer member other than a transfer member having a cleaning device). When manufacturing the transfer member, the relationship between the resistance values is designed in advance, and the power supply connected between the transfer member with the cleaning device and the contact-type charging device to supply a voltage for each purpose is provided. The power supply may be used or a dedicated power supply different from this power supply may be provided to apply a predetermined voltage.

Further, in the first invention, the image carrier may be a drum type image carrier drum.
Further, it may be a belt type image carrier belt,
This is determined depending on whether the image forming apparatus is for a monochrome image, a multi-color image, or a full-color image. In addition, as a contact-type charging device, a roll-type charging roll, a film-type charging film, a brush-type charging brush, or the like can be used as appropriate, and a charging system that applies only DC is also used. However, a type in which DC + AC is applied may be used.

In the first invention, the transfer member of the contact transfer device may be a roll-type transfer roll, a drum-type transfer drum, or a belt-type transfer belt. The transfer roll, the transfer drum, and the transfer belt may be appropriately combined, for example, using an intermediate transfer belt or an intermediate transfer drum as the intermediate transfer body and using a transfer roll as the final transfer body. What type of transfer member is used may be selected as needed when designing the image forming apparatus.

In the first aspect of the present invention, the cleaning device attached to one transfer member constituting the contact type transfer device may be a brush having a cleaning brush, even if it is a blade type having a cleaning blade. It may be of the type, but is preferably a cleaning blade.

The developing device used in the first invention is not particularly limited, and may be a magnetic brush contact type two-component developing type, a non-contact type developing type using magnetic toner, or the like. Regarding this developing device, in particular, in the case of a contact type, since a predetermined potential is applied to the image carrier in the cleaning step, a plurality of developing devices are mounted in an image forming device for a multi-color image or a full-color image. In order to prevent the residual toner of the opposite polarity from flowing back into the developing device and causing color mixing, a retract mechanism is provided for the image carrier, and a shutter mechanism for shielding between the image carrier and the image carrier is provided. It is desirable to use one provided with a control mechanism for stopping the developing roll in the cleaning process, one provided with a control mechanism for displacing the potential of the developing roll in accordance with the potential displacement of the image carrier in the cleaning process, or the like. .

[Second Invention] Next, in a second invention of the present application, an image forming apparatus provided with a contact-type charging device, an image carrier, an exposing device, a developing device, an intermediate transfer member, and a final transfer member In the apparatus, a cleaning device is attached to the final transfer member, a temporary holding member is attached to the intermediate transfer member, and means for applying a predetermined potential gradient is provided between the final transfer member and the contact-type charging device. Further, the temporary holding member is provided with a means for giving a potential gradient to the intermediate transfer member.

Here, the contact-type charging device, the image carrier,
Exposure device, developing device, intermediate transfer member, final transfer member, cleaning device, and means for imparting a potential gradient, and configurations of image carrier, intermediate transfer member and final transfer member (for image carrier and contact transfer device) Configuration) can be considered in the same manner as the case where the intermediate transfer body is used in the first aspect of the invention and the transfer body with the cleaning device is used as the final transfer body, but the temporary holding member attached to the intermediate transfer body is It is preferable to use a brush type brush cleaning device or a roll type roll cleaning device capable of temporarily holding the residual toner of the positive polarity or the opposite polarity.

The intermediate transfer member is composed of, for example, a pair of first intermediate transfer members contacting two image carriers and a second intermediate transfer member contacting the pair of first intermediate transfer members. In such a case, the temporary holding member may be attached to all of the pair of first intermediate transfer member and the second intermediate transfer member, or may be attached only to the pair of first intermediate transfer members. Also, it may be provided only on the second intermediate transfer body side,
Further, it may be attached to only one first intermediate transfer member. Whether the brush cleaning device or the roll cleaning device is used as the temporary holding member attached to the intermediate transfer member depends on whether the remaining toner to be cleaned has positive polarity or reverse polarity, cleaning property, toner holding property, Determined in consideration of resistance value selectivity and the like.

For example, when a transfer voltage is applied to the intermediate transfer member such that no reverse polarity (+) toner is generated, the remaining toner has a positive polarity (-). ) Side, it is necessary to apply a high voltage.
At this time, if the resistance value on the temporary holding member side becomes lower than the resistance value on the intermediate transfer member side, the temporary holding member charges the intermediate transfer member and changes the desired transfer electric field. The potential difference between the body and the body is reduced, and the cleaning property is also reduced. Therefore, it is necessary to set the resistance value on the temporary holding member side higher than the resistance value on the intermediate transfer member side. In such a case, it is preferable to use a roll cleaning device as the temporary holding member. At this time, the amount of the residual toner retained on the roll is determined by the circumferential surface area (that is, the outer diameter) of the roll. For example, in the case of a 13 mmφ cleaning roll, about 200 A4 size images are continuously printed. It can also respond.

On the other hand, when toner of opposite polarity (+) is generated by application of the transfer voltage, it is necessary to apply a positive (−) voltage from the intermediate transfer member to the temporary holding member. In this case, the temporary holding member is charged to the opposite polarity (+) side by the intermediate transfer body, and the cleaning property is reduced. Therefore, it is necessary to set the resistance value of the temporary holding member side to be lower than the resistance value of the intermediate transfer body side. However, in such a case, it is preferable to use a brush cleaning device having low resistance and excellent cleaning properties as the temporary holding member.

Further, for example, a pair of first intermediate transfer members in contact with two of the four image carriers as an intermediate transfer member, and a pair of the first intermediate transfer member and the final transfer member in contact with the pair of first intermediate transfer members When the combination with the second intermediate transfer member is used, the transfer ratio may fluctuate because the second intermediate transfer member transfers toner images of four colors.
Positive (-) residual toner is likely to be generated on the second intermediate transfer member. When the first intermediate transfer member and the second intermediate transfer member are used in combination as described above, each single-color toner image is exposed to the transfer electric field a large number of times (3 to 5 times), and has the opposite polarity (+ 3) Although toner tends to be generated as residual toner, the residual toner having the opposite polarity (+) returns from the second intermediate transfer member to the first intermediate transfer member. Therefore, in such a case, it is preferable to attach a temporary holding member for reverse polarity to the first intermediate transfer member, and to attach a temporary holding member for positive polarity to the second intermediate transfer member.

In the second aspect of the present invention, the temporary holding member temporarily holds part or all of the residual toner of the positive polarity or opposite polarity remaining on the surface of the intermediate transfer member during image formation by the image forming apparatus, Next, in the cleaning mode of the image forming apparatus, the contact type charging device, the image carrier, the intermediate transfer member,
A potential gradient is applied to the temporary holding member and the final transfer member, and the remaining toner including the residual toner held by the temporary holding member is collected on the final transfer member, and the residual toner collected on the final transfer member Is collected by the cleaning device.

For example, in order to attach a temporary holding member for positive polarity to the intermediate transfer member and finally collect the residual toner of positive polarity temporarily collected in the temporary holding member for positive polarity in the final transfer member, It is sufficient to apply a high potential gradient to the (+) side in the direction of the contact type charging device → image carrier → intermediate transfer member → final transfer member and temporary holding member → intermediate transfer member → final transfer member. Similarly, a reverse-polarity temporary holding member is attached to the intermediate transfer member, and the reverse-polarity residual toner temporarily collected in the reverse-polarity temporary holding member is contacted in order to finally collect the final transfer member. A high potential gradient may be applied to the (+) side in the direction of the mold charging device ← image carrier ← intermediate transfer member ← final transfer member and temporary holding member ← intermediate transfer member ← final transfer member. Then, two temporary holding members for positive polarity and reverse polarity are attached to the intermediate transfer member, and the remaining positive and negative polarity toners temporarily collected in these temporary holding members are finally transferred to the final transfer member. In order to collect the data, the above-described two operations may be repeated.

Further, in the second invention, a brush cleaning device is provided for cleaning the image carrier and temporarily holding the residual toner remaining on the surface of the image carrier.
A temporary holding member such as a roll cleaning device may be provided. In this case as well, the remaining toner temporarily held by the temporary holding member for the image carrier is transferred to the temporary holding member attached to the intermediate transfer member. In the same manner as described above, the toner can be finally collected on the final transfer body and collected by the cleaning device.

[Regarding the Third Invention] The third invention of the present application further comprises a charging device, an image carrier, an exposure device, a developing device,
In an image forming apparatus provided with an intermediate transfer member and a final transfer member, a temporary holding member is attached to the intermediate transfer member, and a cleaning device is attached to the final transfer member. And / or temporarily retains a part or all of the residual toner having the same polarity and / or opposite polarity, and in the cleaning mode of the image forming apparatus, causes a potential gradient between the final transfer member, the intermediate transfer member, and the temporary holding member. Forming
The remaining toner including the residual toner temporarily held by the temporary holding member is collected on the final transfer body, and the residual toner collected on the final transfer body is collected by the cleaning device.

Here, in the third invention, the image carrier, the exposure device, the developing device, the intermediate transfer member, the final transfer member, the temporary holding member, the cleaning device, the means for imparting a potential gradient, The configurations of the carrier, the intermediate transfer body, and the final transfer body (the configurations of the image carrier and the contact-type transfer device) are the same as those in the second aspect of the invention. As in the second invention, a contact-type charging device or a non-contact-type charging device such as a corotron may be used.

[Regarding Timing of Entering Cleaning Mode] In the first to third aspects of the present invention, the timing at which cleaning is performed by the cleaning device attached to the transfer member may be, for example, an interlock switch (I / L) when the power is turned on. ON, Cycle-in / Cycle-out, Continuous image formation (Each number of sheets),
At the time of performing the process control, at the time of inputting the cleaning command, and the like.

Here, for the cleaning operation when the power is turned on, the main motor is rotated immediately after the power is turned on.
The cleaning mode for the residual toner of the positive polarity (hereinafter referred to as “positive electrode cleaning”) is operated, and then the cleaning mode for the residual toner of the opposite polarity (hereinafter referred to as “reverse polarity cleaning”) is operated. The remaining toner remaining on the charging device, the image carrier, the contact transfer device (intermediate transfer member and the final transfer member), which cannot be cleaned in the worst case by this operation, has a positive polarity. Can be prevented from occurring.

Next, the cleaning operation when the I / L is turned on is the same as the case when the power is turned on when a simple machine (cover) opening / closing operation is performed. However, as for the cleaning at the time of I / L ON after the conveyance failure (paper jam) of the recording sheet, since a relatively large amount of the residual toner of the positive polarity remains, the cleaning of the positive electrode → the cleaning of the reverse electrode → the cleaning of the positive electrode → It is good to work in conjunction with reverse polarity cleaning. In this case, too, the remaining toner remaining on the charging device, image carrier, contact type transfer device (intermediate transfer member and final transfer member), etc., which cannot be cleaned at worst, has a positive polarity. That is, it is possible to prevent a problem such as fogging during the subsequent image formation.

In the cleaning operation at the time of cycle-in / cycle-out, at the start of image formation,
After the rotation of the main motor is started, the reverse polarity cleaning is operated, and then the normal image forming process is operated. In this case, if a predetermined time is taken after starting the normal image forming process and before starting the actual image formation, the positive electrode cleaning is performed during this time. After the image forming step is completed, the reverse polarity cleaning is operated again,
The opposite polarity residual toner generated during the image forming process is cleaned, the main motor is stopped, and the process ends.

Further, with respect to the cleaning operation at the time of forming a continuous image (every constant number of sheets), when a continuous image is formed on a large number of sheets, the remaining toner of the opposite polarity accumulates in the contact type charging device and causes image defects such as fog. This is performed in order to prevent this from happening, and when the number of image formation reaches a predetermined number,
The image forming process is temporarily interrupted, and reverse polarity cleaning → positive electrode cleaning → reverse polarity cleaning is operated. Thus, continuous image formation can be performed while preventing image defects such as fogging caused by accumulation of residual toner of the opposite polarity in the contact-type charging device.

Further, as for the cleaning operation at the time of performing the process control, the same operation as at the time of the above-described cleaning at the time of forming a continuous image (every constant number of sheets) is performed at the time of performing the process control, and image defects such as fogging due to residual toner having the opposite polarity are removed. To prevent.

Further, the cleaning operation at the time of inputting the cleaning command is a command to be executed when an image defect such as fog occurs even after performing the above-mentioned cleaning operations 1 to 3, and reverse polarity cleaning → positive electrode cleaning → reverse polarity cleaning To work.

And the above cleaning operation ~
It is not necessary to operate all of them, and only one of them may be selected and operated, or if necessary, two or more may be operated in combination as appropriate, but preferably two or more are operated. It is better to combine some of the two or more types.

[Necessary Potential Difference (Electric Potential Gradient) Between Each Member] In the present invention, a contact-type charging device, an image carrier,
Regarding the potential difference (potential gradient) to be applied between the members such as the contact transfer device (the intermediate transfer member and the final transfer member), the potential difference between the members is such that the residual toner moves at a rate close to 100%. There is a need. If the transfer electric field in the transfer step is within a specified range {the required transfer electric field (having a certain range)}, a transfer rate close to 100% can be obtained, and the image is developed on the image carrier. Normally, the charge of the toner is normally distributed on both sides of the high charge side / low charge accumulation side with respect to the center value.

Further, for example, the charge of the toner is set to −25 ± 20.
In the case of μC / g, the residual toner remaining due to the insufficient transfer electric field in the transfer step is usually the toner on the high charging side, and −
The residual toner having a charge of 35 μC / g or more and remaining due to an excessive transfer electric field in the transfer process is usually a low-charge side toner and generally has a charge of −5 to +10 μC / g. When the machine is forcibly stopped during image formation due to a paper jam or the like, the residual toner remaining on the image carrier and the contact transfer device usually has no change in electric charge and is -25 ± 20 μC / g.

The relationship between the potential difference between members for each charge of the residual toner and the toner movement (cleaning rate) between the members is as shown in FIG. 1, and the charge is −25 ± 20 μm.
In the case of C / g toner, it can be seen that the cleaning rate reaches almost 100% if there is a potential difference of 300 to 800V.

Accordingly, in the present invention, the charge of the toner used in the image forming apparatus is checked, and the relationship between the potential difference between the members for each charge of the remaining toner and the movement (cleaning rate) of the toner between the members is checked. It is possible to easily design what potential difference (potential gradient) should be applied between members such as an apparatus, an image carrier, and a contact transfer device (an intermediate transfer member and a final transfer member).

[0062]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be specifically described below based on examples. Embodiment 1 FIG. 2 shows a tandem type full-color image forming apparatus according to Embodiment 1 of the present invention.

The full-color image forming apparatus of the first embodiment has the same structure as that of FIG. 19 described above, and is for yellow (Y), magenta (M), cyan (C), And four photoconductors (image carriers) 10, 20, 30, 40 for black (K), and these photoconductors 10, 20, 30, 40
Roll (contact type charging device) that comes into contact with the surface 11, 21, 31,
41, exposure devices 12, 22, 32, 42 and developing devices 13, 23, 3
3, 43 and 2 of the above four photoconductors 10, 20, 30, 40
A first intermediate transfer roll 51 that contacts one of the photoconductors 10 and 20, and a first intermediate transfer roll 52 that contacts the other two photoconductors 30 and 40; A second intermediate transfer roll 53 that contacts the rolls 51 and 52, and a final transfer roll 61 that contacts the second intermediate transfer roll 53,
The image forming apparatus includes a transport roll 91 and a fixing device 70.

Also, in the first embodiment, each single-color toner image formed by the two photosensitive members 10 and 20 is transferred to the first intermediate transfer roll 51, as in the case of FIG. After being transferred to the second intermediate transfer roll 53,
Each monochromatic toner image formed by the two photoconductors 30 and 40 is transferred to a first intermediate transfer roll 52 and then to a second intermediate transfer roll 53, and is superimposed on the second intermediate transfer roll 53. Then, the sheet is transferred onto the sheet (recording sheet) P conveyed between the transfer roller 91 and the final transfer roll 61 in contact with the second intermediate transfer roll 53, and is transferred onto the sheet P. The fixed toner image is fixed by the fixing device 70.

In the first embodiment, a DC voltage of about -840 V is applied to the photoreceptors 10, 20, 30, and 40 by the charging rolls 11, 21, 31, and 41, whereby about -300 V is applied. And the exposure devices 12, 22,
When the electrostatic latent image is written at 32 and 42, the surface potential is eliminated to about -60V.

In the first embodiment, the developing device 1
3, 23, 33 and 43 are a developing roll 131 and a developer amount regulating member 1
32, a developer transporting member 133, and a magnetic brush contact type two-component developing type developing device including an auger 134 for transporting and agitating the developer. The developer amount regulating member
The amount of the developer conveyed to the developing unit while being regulated by 132 is about 30 to 40 g / m ^2.
The charge amount of the toner existing on the surface is approximately −20 to −30 μC.
/ G. The developing devices 13, 23, 33, 43 have A
The development is carried out by applying a C + DC development voltage. The development voltage is 4 kHz for AC, 1.6 kVpp, and about -230 V for DC.

Further, the first intermediate transfer rolls 51 and 52 used in the first embodiment are formed by providing a silicon rubber layer on a metal pipe and further coating a high release layer thereon. The resistance value is usually 10 ⁵ to 10 ⁹
Although a range of Ω can be used, it is set to about 10 ⁸ Ω here. The surface potential required to transfer a toner image from the photoconductors 10, 20, 30, 40 to the first intermediate transfer rolls 51, 52 is usually in the range of about +250 to 500 V, The optimum value is set according to the state, the ambient temperature, the humidity, and the like. In this case, the surface potential is set to about +380 V.

The second intermediate rotation used in the first embodiment
The transfer roll 53 is also similar to the first intermediate transfer rolls 51 and 52 described above.
A silicon rubber layer on the metal pipe,
It is formed by coating a high release layer on top,
The resistance value is usually 10 ⁸-10¹²Ω range
Can be used, but here 10¹¹Ω.
Then, from the first intermediate transfer rolls 51 and 52,
Required to transfer the toner image to the intermediate transfer roll 53
The surface potential is usually in the range of about +600 to 1200V.
Optimum depending on toner charging state, ambient temperature, humidity, etc.
The value is set, but here, the surface potential +880
V and the potential difference is about + 500V
You.

Further, in the first embodiment, the final transfer roll 61 is provided with a urethane rubber layer on a metal pipe and further coated thereon, and its resistance value is usually 10 ⁶ to Although a range of 10 ⁹ Ω can be used, it is set to about 10 ⁸ Ω here. The final transfer roll 61 is used to transfer the toner image from the second intermediate transfer roll 53 onto a sheet (recording sheet).
Is usually in the range of about +1200 to 5000 V, and the optimum value is set according to the ambient temperature, humidity, the type of paper P (resistance value, etc.), but the constant current method is adopted here. About + 6μA under normal temperature and normal humidity
Is applied, and the transfer voltage is approximately appropriate +1600 to 2000 V
Have gained a degree.

In the full-color image forming apparatus of the first embodiment, unlike the full-color image forming apparatus shown in FIG. 19, a blade cleaning device 71 having a cleaning blade 72 is attached to the final transfer roll 61. A predetermined voltage is applied to each of the charging rolls 11, 21, 31, 41, the first intermediate transfer rolls 51, 52, the second intermediate transfer roll 53, and the final transfer roll 61 to charge each of the charging rolls 11, 21, 31, 41. Rolls 11, 21, 31, 41, each photoconductor 10, 20, 30, 40, each first intermediate transfer roll 51, 52, second intermediate transfer roll 53,
Then, a predetermined potential gradient is formed between the final transfer roll 61 and the final transfer roll 61.

In the first embodiment, in the cleaning mode using the blade cleaning device 71, each of the charging rolls 11, 21, 31, 41 is set to −840 during the cleaning of the positive electrode.
V, each photoconductor 10, 20, 30, 40 is -300V, each first intermediate transfer roll 51, 52 is + 380V, the second intermediate transfer roll 53 is + 880V, and the final transfer roll 61 is + 1600V.
V, and at the time of reverse polarity cleaning, each charging roll 11, 21, 31, 41 is 0V, and each photoconductor 10, 20, 30, 40 is-.
300V, the first intermediate transfer rolls 51 and 52 are -800
V, the second intermediate transfer roll 53 is set to -1300V, and the final transfer roll 61 is set to -2000V. In the first embodiment, each of the charging rolls 11 and
The voltage supply to the first, second and third intermediate transfer rolls 51, 52, the second intermediate transfer roll 53, and the final transfer roll 61 is performed by supplying a voltage to the metal part (shaft or pipe) of each member. It is done in the method of doing.

Next, a timing sequence of an image forming job in the full-color image forming apparatus according to the first embodiment will be described. In the description of the timing sequence, reference numerals of respective members indicate only representative examples. FIG.
In the area A, the cleaning mode at the time of cycle-in / cycle-out is shown, and here, the reverse polarity cleaning is performed. Area B indicates an image forming step,
Continuous image formation of 30 sheets is performed. Further, the area C is a cleaning mode in which a constant number of sheets (here, 30 sheets) are set during continuous image formation, and reverse polarity cleaning → positive electrode cleaning → reverse polarity cleaning is performed.

Here, the positive electrode cleaning and the reverse electrode cleaning will be described with reference to the cleaning diagrams shown in FIGS. 4 to 6. At the time of the positive electrode cleaning shown in FIG. Is -840
V, the photoreceptor 10 is at -300 V, and the first intermediate transfer roll is
51 is at +380 V, the second intermediate transfer roll 53 is at +880
V, and the potential of the final transfer roll 61 is set to +1600 V, and a potential gradient is applied between these members. Positive (-) residual toner remaining on each member is charged roll 11 → photoconductor. 10 → the first intermediate transfer roll 51 → the second intermediate transfer roll 53 → the final transfer roll 61.
As shown in (1), it is removed by a blade cleaning device 71 attached to the final transfer roll 61. At this time, the opposite polarity (+) residual toner remaining on each member moves in the opposite direction to the positive polarity (−) residual toner, and collects on the charging roll 11 as shown in FIG.

At the time of the reverse polarity cleaning shown in FIG. 6, the charging roll 11 is set to 0 V as described above,
Is -300 V, the first intermediate transfer roll 51 is -800 V
The second intermediate transfer roll 53 has a voltage of -1300 V,
The potential of the final transfer roll 61 is set to −2000 V, and a potential gradient is applied between these members.
In particular, the remaining toner of the opposite polarity (+) adhering to the charging roller 11 is charged roller 11 → photoconductor 10 → first intermediate transfer roller 51 →
The process proceeds from the second intermediate transfer roll 53 to the final transfer roll 61, and is removed by a blade cleaning device 71 attached to the final transfer roll 61, as shown in FIG.

Therefore, according to the full-color image forming apparatus of the first embodiment, not only the residual toner of the positive polarity but also the residual toner of the opposite polarity can be obtained by appropriately performing the positive cleaning and the reverse cleaning in the image forming job. It can be efficiently and reliably removed.

The developing device used in the first embodiment
13, 23, 33, and 43, when using a contact type developing device such as a magnetic brush contact type two-component developing system in which the tip of the magnetic brush contacts the surface of the photoreceptor 10, the reverse polarity cleaning is performed. The opposite polarity (+) residual toner that has come out of the charging roller 11 to the surface of the photoreceptor 10 may come into contact with the magnetic brush of the developing device 13 and be taken into the developer of the developing device 13 to cause color mixing.

If such a problem of color mixing is concerned, the developing device 13 is used as shown in FIGS. 8 (a) and 8 (b).
As shown in FIG. 8, a developing device 13 with a retracting mechanism having a pulling device 135 as shown in FIG.
As shown in FIG. 2B, the toner is retracted to the retracted position and separated from the photoreceptor 10, thereby preventing the residual toner of the opposite polarity (+) from being taken into the developer of the developing device 13 and causing color mixing. Is also good.

Similarly, when there is a concern about the problem of color mixing, as shown in FIGS.
A shutter mechanism 136 having a shutter 137 made of a film is provided on the photoconductor 10, and a shutter 137 is inserted between the photoreceptor 10 and the developing roll 131 of the developing device 13 at the time of reverse polarity cleaning. 131 so as to prevent the residual toner of opposite polarity (+) from being taken into the developer of the developing device 13 and causing color mixture.

Second Embodiment Next, a tandem type full-color image forming apparatus according to a second embodiment of the present invention will be described. Note that, in the following description, reference numerals for respective members indicate only representative examples. The tandem-type full-color image forming apparatus according to the second embodiment has the same basic configuration as that of the first embodiment shown in FIG. 2, but each charging roll 11, each first intermediate transfer roll 51, and a second intermediate transfer roller. The means for imparting a potential gradient to the transfer roll 53 and the final transfer roll 61 is different from that in the first embodiment, and a predetermined voltage is applied to the final transfer roll 61 and the photosensitive drum 10 is grounded. The first intermediate transfer roll 51 and the second intermediate transfer roll 53 located in between are electrically floated, and these final transfer rolls 6
1, second intermediate transfer roll 53, each first intermediate transfer roll 5
1 and the relationship between the resistance values of each photoconductor 10 and each charging roll 1
A predetermined potential gradient is applied between each charging roll 11, each photoconductor 10, each first intermediate transfer roll 51, the second intermediate transfer roll 53, and the final transfer roll 61 in relation to the voltage applied to 1. Is formed.

In the second embodiment, in the same manner as in the first embodiment, in the cleaning mode using the blade cleaning device 71, when cleaning the positive electrode, each of the charging rolls 11 is set to −840V, and each of the photosensitive members 10 is set to −. 300
V, the first intermediate transfer roll 51 becomes +380 V, the second intermediate transfer roll 53 becomes +880 V, and the final transfer roll 61 becomes +1600 V. In the case of the reverse polarity cleaning, each charging roll 11 becomes 0 V, The photoreceptor 10 has a voltage of -300 V, each first intermediate transfer roll 51 has a power of -800 V, a second intermediate transfer roll 53 has a power of -1300 V, and a final transfer roll 61 has a power of -20.
It is set to be 00V.

Here, the positive electrode cleaning and the reverse electrode cleaning will be described with reference to the cleaning diagrams shown in FIGS. 10 to 13. At the time of the positive electrode cleaning shown in FIG. 10, it is completely different from the case of the first embodiment shown in FIG. Similarly, a potential is set to each member, a potential gradient is given between these members, and the positive (-) residual toner remaining in each member finally moves to the final transfer roll 61, As shown in FIG. 11, the toner is removed by a blade cleaning device 71 attached to the final transfer roll 61. And at this time,
The opposite polarity (+) residual toner remaining on each member moves in the opposite direction to the positive polarity (−) residual toner, and collects on the charging roll 11 as shown in FIG.

At the time of the reverse polarity cleaning shown in FIG. 12, a DC voltage of -2000 V is applied to the final transfer roll 61, and the second intermediate transfer roll 53 between the photosensitive drum 10 and the ground.
Is -1300V, and the first intermediate transfer roll 51 is-
The photoreceptor 10 settles at 800 V, and is in contact with the first intermediate transfer roll 51. The photoreceptor 10 is charged by the first intermediate transfer roll 51 and set at -300 V. Further, 0 V is applied to the charging roll 11 by grounding. You. Therefore, just as in the case of Example 1 above, these final transfer rolls
61, second intermediate transfer roll 53, first intermediate transfer roll 5
1, a potential gradient is applied between the photoreceptor 10 and the charging roll 11, and the remaining polarity toner (+) remaining on each member, especially the charging roll 11, is finally transferred to the final transfer roll 61. Then, as shown in FIG. 13, it is removed by a blade cleaning device 71 attached to the final transfer roll 61.

Therefore, also in the case of the full-color image forming apparatus of the second embodiment, similarly to the first embodiment, only the positive-polarity residual toner is removed by appropriately inserting the positive electrode cleaning and the reverse polarity cleaning into the image forming job. In addition, the residual toner having the opposite polarity can be efficiently and reliably removed.

Embodiment 3 Next, FIG. 14 shows a tandem-type full-color image forming apparatus of Embodiment 3. Note that, in the following description, reference numerals for each member may indicate only representative examples. In the case of the third embodiment, unlike the case of the first embodiment, a pair of first intermediate transfer rolls 51,
52 and the second intermediate transfer roll 53 are provided with brush-type first cleaning members 81 and 82 and a second cleaning member 83, respectively, which are temporary holding members, and the first cleaning members 81 and 82 have a first intermediate member. A higher voltage can be applied in the range of 300 to 800 V to the + side than the transfer rolls 51 and 52, and the second cleaning member 83 can be applied in the range of 300 to 800 V to the + side than the second intermediate transfer roll 53. High voltage can be applied.

In the third embodiment, at the time of image formation of an image forming job, each charging roll 11 is -840 V, each photoconductor 10 is -300 V, and each first intermediate transfer roll 51, 52.
+ 380V, the second intermediate transfer roll 53 is + 880V,
And the final transfer roll 61 is set to +1600 V, the first cleaning members 81 and 82 are set to +880 V, and the second cleaning member 83 is set to +1380 V. For example, each of the first cleaning members 8 is set at the time of continuous image formation.
The positive (−) residual toner generated in the first and second intermediate transfer rolls 53 is immediately held by the first cleaning members 81 and 82 and the second cleaning member 83, respectively.

For this reason, according to the full-color image forming apparatus of the third embodiment, the first intermediate transfer rolls 51 and 52 and the second intermediate transfer roll 53 have the positive polarity ( -) Even if residual toner is generated, the first cleaning members 81 and 82 and the second cleaning member 83 attached to the first intermediate transfer rolls 51 and 52 and the second intermediate transfer roll 53 temporarily remove the residual toner. Can be held.

Further, in the third embodiment, in the cleaning mode by the blade cleaning device 71,
Each charging roll 11, each photoconductor 10, each first intermediate transfer roll
51, 52, the second intermediate transfer roll 53, and the final transfer roll 6
1 and the same potential gradient as in the first embodiment, and the first cleaning member
81, 82 to 0V, second cleaning member 83 to + 380V
The first cleaning members 81 and 82 are set to -300 V, and the second cleaning member 83 is set to -800 V during reverse polarity cleaning.

Therefore, in the case of the third embodiment,
In the cleaning mode of the image forming job, when cleaning the positive electrode, each charging roll 11 is −840 V, each photoconductor 10 is −300 V, each first intermediate transfer roll 51 and 52 is +380 V, and the second intermediate transfer roll 53 is used. Is set to +880 V, the final transfer roll 61 is set to +1600 V, the first cleaning members 81 and 82 are set to 0 V, the second cleaning member 83 is set to +380 V, and in the case of reverse polarity cleaning, Each charging roll 11 is at 0V,
Each photoconductor 10 has a voltage of -300 V, each first intermediate transfer roll 51,
52 is -800 V, the second intermediate transfer roll 53 is -1300
V and the final transfer roll 61 are set to −2000 V, and each of the first cleaning members 81 and 82 is −
300V, and the second cleaning member 83 is -800
V is set.

Therefore, according to the third embodiment, at the time of cleaning the positive electrode, as shown in FIG. 15, the above-mentioned potentials are set to the respective members, and a potential gradient is applied between these members. Positive polarity remaining on the member (-)
As shown in FIG. 16, the residual toner finally includes the positive (−) residual toner collected by the second cleaning member 83 of the second intermediate transfer roll 53, and finally reaches the final transfer roll 61. Then, as shown in FIG.
Is removed by the blade cleaning device 71 attached to the. Then, at this time, the opposite polarity (+) residual toner remaining on each member shifts in the opposite direction to the positive polarity (−) residual toner, and as shown in FIG. It gathers on the first cleaning members 81 and 82 of the rolls 51 and 52 and the charging roll 11.

At the time of the reverse polarity cleaning shown in FIG. 17, as described above, each charging roll 11 is set to 0 V, each photoconductor 10 is set to -300 V, and each first intermediate transfer roll 51, 52.
To -800 V, and the second intermediate transfer roll 53 to -1300.
V, the final transfer roll 61 is set to −2000 V, the first cleaning members 81 and 82 are set to −300 V, the second cleaning member 83 is set to −800 V, and the potential is set between these members. Gradient is applied to each member, especially the charging roller 11, and the remaining toner of the opposite polarity (+) collected by the first cleaning members 81 and 82 is charged roller 11 → photoconductor 10 → first toner. Intermediate transfer roll 51
[First cleaning member 81, 82 → first intermediate transfer roll
51] → second intermediate transfer roll 53 (second cleaning member
83 → second intermediate transfer roll 53) → final transfer roll 61, and are removed by a blade cleaning device 71 attached to the final transfer roll 61, as shown in FIG.

Therefore, according to the full-color image forming apparatus of the third embodiment, in the actual image forming job, the optimum transfer potential and the optimum transfer potential are determined by factors such as the ambient temperature, humidity, toner charge amount, and developer amount. The first embodiment can prevent not only an image defect such as a transfer ghost due to a positive (-) residual toner generated due to the voltage setting, but also the first embodiment.
Similarly to the cases 2 and 3, by appropriately performing the positive electrode cleaning and the reverse polarity cleaning in the image forming job, not only the positive polarity residual toner but also the reverse polarity residual toner can be efficiently and reliably removed.

[Fourth Embodiment] Further, the tandem type full-color image forming apparatus of the fourth embodiment is different from that of the third embodiment in that the first cleaning member attached to the pair of first intermediate transfer rolls 51 and 52 is different from that of the third embodiment. The potential of 81, 82 is -100 to -50 from the potential applied to the first intermediate transfer rolls 51, 52.
0 V is set lower, and the second intermediate transfer roll
Regarding the second cleaning member 83 attached to 53, the potential applied to the second intermediate transfer roll 53 is +100 to +5
It is set higher by about 00V.

For this reason, in the full-color image forming apparatus according to the fourth embodiment, in the actual image forming job,
Positive (-) residual toner generated due to the optimal transfer potential and voltage setting due to factors such as changes in the ambient temperature, humidity, toner charge amount, developer amount, etc. The second cleaning member 83 attached to the first intermediate transfer rolls 51 and 52 and the second intermediate transfer roll 53 during the secondary transfer between the second intermediate transfer roll 53 and the second intermediate transfer roll 53 and the final transfer The reverse polarity (-) residual toner generated by the influence of the ash discharge or the like during the tertiary transfer with the roll 61 is transferred to the first intermediate transfer rolls 51 and 52 before flowing backward to the charging roll 11 and accumulating. It is held by the attached second cleaning member 83, whereby contamination of the charging roll 11 can be prevented as much as possible.

Also in the fourth embodiment, the same cleaning mode by the blade cleaning device 71 as in the third embodiment is applied, and the positive (-) residual toner remaining on each member by the positive electrode cleaning is finally removed. After being transferred to the final transfer roll 61, it is removed by the blade cleaning device 71, and adheres to each member, particularly the charging roll 11, by reverse polarity cleaning.
The opposite polarity (+) residual toner collected by 81 and 82 is finally transferred to the final transfer roll 61, and can be removed by the blade cleaning device 71.

[0095]

According to the image forming apparatus of the present invention, even if the residual toner having the opposite polarity is generated in the image forming apparatus, it can be effectively recovered only by performing simple system control.

[Brief description of the drawings]

FIG. 1 is a graph showing a relationship between a potential difference between members for each charge of residual toner and a toner movement (cleaning rate) between members.

FIG. 2 is an explanatory diagram illustrating a configuration of a full-color image forming apparatus according to the first embodiment of the present invention.

FIG. 3 is a graph showing a timing sequence according to the first embodiment shown in FIG. 2;

FIG. 4 is an explanatory diagram illustrating a state immediately after the start of a cycle at the time of positive electrode cleaning in Example 1 illustrated in FIG. 2;

FIG. 5 is an explanatory diagram showing a state at the end of a cycle at the time of cleaning the positive electrode in the first embodiment shown in FIG. 2;

FIG. 6 is an explanatory diagram showing a state immediately after the start of a cycle at the time of reverse polarity cleaning of the first embodiment shown in FIG. 2;

FIG. 7 is an explanatory diagram illustrating a state at the end of a cycle at the time of reverse polarity cleaning of the first embodiment illustrated in FIG. 2;

FIG. 8 is a schematic explanatory view showing a retract mechanism provided in the developing device of the first embodiment shown in FIG. 2 as necessary.

FIG. 9 is a schematic explanatory view showing a shutter mechanism provided in the developing device of the first embodiment shown in FIG. 2 as necessary.

FIG. 10 is an explanatory diagram illustrating a state immediately after the start of a cycle during positive electrode cleaning in Example 2.

FIG. 11 is an explanatory diagram illustrating a state at the end of a cycle during positive electrode cleaning in Example 2.

FIG. 16 is an explanatory diagram illustrating a state immediately after the start of a cycle at the time of reverse polarity cleaning according to the second embodiment.

FIG. 13 is an explanatory diagram illustrating a state at the end of a cycle at the time of reverse polarity cleaning according to the second embodiment.

FIG. 14 is an explanatory diagram illustrating a configuration of a full-color image forming apparatus according to a third embodiment of the present invention.

FIG. 15 is an explanatory diagram illustrating a state immediately after the start of a cycle during positive electrode cleaning in Example 3.

FIG. 16 is an explanatory diagram showing a state at the end of a cycle during positive electrode cleaning in Example 3.

FIG. 17 is an explanatory diagram illustrating a state immediately after the start of a cycle at the time of reverse polarity cleaning according to the third embodiment.

FIG. 18 is an explanatory diagram illustrating a state at the end of a cycle at the time of reverse polarity cleaning according to the third embodiment.

FIG. 19 is a configuration explanatory view showing a full-color image forming apparatus studied as a premise of the present invention.

[Explanation of symbols]

10, 20, 30, 40: Photoconductor (image carrier), 11, 21, 31, 41: Charging roll (contact type charging device), 12, 22, 32, 42: Exposure device, 13, 23, 33, 43: developing device, 51, 52: first intermediate transfer roll (intermediate transfer body), 53: second intermediate transfer roll (intermediate transfer body), 61: final transfer roll (final transfer body), 71 ...
Cleaning device, 72 ... Cleaning blade, 81, 82
... First cleaning member (temporary holding member), 83 ... Second cleaning member (temporary holding member), P ... Paper (recording sheet).

Continuation of the front page (72) Inventor Tadashi Sueyama 3-7-1, Funai, Iwatsuki-shi, Saitama, Fuji Xerox Co., Ltd. , Fuji Xerox Co., Ltd. Iwatsuki Office F-term (reference) 2H027 EA09 EB04 EB06 ED09 ED27 ED28 EE07 EF09 EF11 2H032 AA05 AA15 BA05 BA08 BA23 BA30 CA13 2H034 AA00 BA05 BC07 BC08 BC09 BC10 BD07 BD08 BD09 BD10 BF00

Claims (35)

[Claims] An image bearing member, a contact-type charging device that contacts and charges the image bearing member, an exposure device that forms a latent image on the surface of the charged image bearing member, and an image forming member that is formed on the surface of the image bearing member. A developing device that develops a latent image to form a toner image; and a contact device that includes at least one transfer member, and contacts the image carrier to transfer the toner image formed on the surface of the image carrier onto a recording sheet. A cleaning device is attached to one of the transfer members constituting the contact type transfer device, and the cleaning device is attached when the image forming apparatus is in a cleaning mode. A potential gradient is formed between the transfer member with the cleaning device and the contact type charging device, and the residual toner remaining on the contact type charging device, the image carrier, and the contact type transfer device is collected on the transfer member with the cleaning device. An image forming apparatus wherein the residual toner collected on the transfer member with the cleaning device is collectively collected by a cleaning device. 2. The transfer member of a contact type transfer device is constituted by a final transfer member that comes into contact with an image carrier, and the final transfer member is used as a transfer member with a cleaning device, and the final transfer member, the image carrier, and the contact type transfer member. 2. The image forming apparatus according to claim 1, wherein a potential gradient is formed between the charging devices, and residual toner remaining on the contact type charging device and the image carrier is collected on a final transfer member. 3. The image forming apparatus according to claim 2, wherein a voltage is applied to the contact-type charging device and the final transfer member to form a potential gradient between the contact-type charging device, the image carrier, and the final transfer member. 4. A contact-type transfer device comprising an intermediate transfer member in contact with an image carrier and a final transfer member in contact with the intermediate transfer member, wherein a contact-type charging device, an image carrier, an intermediate transfer member, And forming a potential gradient between the transfer member and the final transfer member.
An image forming apparatus according to claim 1. 5. A contact-type charging device, wherein a potential gradient is formed between the final transfer member, an intermediate transfer member, an image carrier, and a contact-type charging device, wherein the final transfer member is a transfer member with a cleaning device.
The image forming apparatus according to claim 4, wherein residual toner remaining on the image carrier and the intermediate transfer member is collected on a final transfer member. 6. A potential gradient is formed between the intermediate transfer member, the image carrier, and the contact type charging device, and between the intermediate transfer member and the final transfer member as a transfer member with a cleaning device. 5. The image forming apparatus according to claim 4, wherein residual toner remaining on the image carrier, the contact-type charging device, and the final transfer member is collected on an intermediate transfer member. 7. A method for applying a voltage to the contact-type charging device, the intermediate transfer member, and the final transfer member to form a potential gradient between the contact-type charging device, the image carrier, the intermediate transfer member, and the final transfer member. Item 7. The image forming apparatus according to item 5 or 6. 8. Applying a voltage to the final transfer member and electrically floating the intermediate transfer member between the image transfer member and the grounded image bearing member, thereby reducing the resistance values of the final transfer member, the intermediate transfer member, and the image bearing member. 6. The image forming apparatus according to claim 5, wherein a potential gradient is formed between the contact type charging device, the image carrier, the intermediate transfer member, and the final transfer member in a relationship between the relationship and a voltage applied to the contact type charging device. . 9. An image bearing member for cyan, magenta,
The image forming apparatus includes four image carriers for yellow and black, and a contact-type transfer device includes an intermediate transfer member that contacts the four image carriers and a final transfer member that contacts the intermediate transfer member. The image forming apparatus according to claim 1, wherein a potential gradient is formed between each contact-type charging device that contacts each image carrier, each image carrier, the intermediate transfer member, and the final transfer member. 10. A potential gradient is formed between the final transfer body, the intermediate transfer body, each image carrier, and each contact-type charging device by using the final transfer body as a transfer body with a cleaning device. The image forming apparatus according to claim 9, wherein residual toner remaining on the image carrier and the intermediate transfer body is collected on a final transfer body. 11. A potential gradient is formed between the intermediate transfer member, each image carrier, and each contact-type charging device, and between the intermediate transfer member and the final transfer member, using the intermediate transfer member as a transfer member with a cleaning device. The image forming apparatus according to claim 9, wherein residual toner remaining on each of the contact-type charging devices, each of the image carriers, and the final transfer member is collected on an intermediate transfer member. 12. A voltage is applied to each of the contact-type charging device, the intermediate transfer member, and the final transfer member, and the final transfer member, the intermediate transfer member,
The image forming apparatus according to claim 10, wherein a potential gradient is formed between each image carrier and each contact-type charging device. 13. A voltage is applied to the final transfer member, and the intermediate transfer member between each of the grounded image bearing members is electrically floated, and the final transfer member, the intermediate transfer member, and the resistance of each image bearing member are provided. 11. A potential gradient is formed between the final transfer member, the intermediate transfer member, each image carrier, and each contact type charging device in a relationship between a value relationship and a voltage applied to each contact type charging device. The image forming apparatus as described in the above. 14. An image carrier comprising four image carriers for cyan, magenta, yellow, and black, and the contact type transfer device is provided with two image carriers among the four image carriers. A pair of first intermediate transfer members that contact the body, a second intermediate transfer member that contacts the pair of first intermediate transfer members, and a final transfer member that contacts the second intermediate transfer member. Wherein a potential gradient is formed between each contact-type charging device that contacts each image carrier, each image carrier, each first intermediate transfer body, second intermediate transfer body, and final transfer body. Item 2. The image forming apparatus according to Item 1. 15. A potential gradient between the final transfer member, the second intermediate transfer member, each of the first intermediate transfer members, each of the image carriers, and each of the contact-type charging devices, wherein the final transfer member is a transfer member with a cleaning device. 15. The image forming apparatus according to claim 14, wherein the remaining toner remaining on each contact-type charging device, each image carrier, each first intermediate transfer member, and the second intermediate transfer member is collected on a final transfer member. . 16. A method according to claim 16, wherein the second intermediate transfer member is a transfer member with a cleaning device, between the second intermediate transfer member, each first intermediate transfer member, each image carrier, and each contact-type charging device.
A potential gradient is formed between the second intermediate transfer member and the final transfer member, and the remaining toner remaining on each contact-type charging device, each image carrier, each first intermediate transfer member, and the final transfer member is removed. 15. The image forming apparatus according to claim 14, wherein the image is collected on two intermediate transfer members. 17. A voltage is applied to each contact-type charging device, each first intermediate transfer member, second intermediate transfer member, and final transfer member, and each contact-type charging device, each image carrier, and each first transfer member are charged. 17. The image forming apparatus according to claim 15, wherein a potential gradient is formed between the intermediate transfer member, the second intermediate transfer member, and the final transfer member. 18. A voltage is applied to the final transfer member, and each of the first intermediate transfer member and the second intermediate transfer member between each of the image transfer members grounded is electrically floated. The first intermediate transfer body, the second intermediate transfer body, and each of these contact-type charging devices in the relationship between the resistance value of the image carrier and the voltage applied to the contact-type charging device, each image carrier, The image forming apparatus according to claim 15, wherein a potential gradient is formed between each of the first intermediate transfer member, the second intermediate transfer member, and the final transfer member. 19. Applying a voltage to the final transfer member and electrically floating the second intermediate transfer member between each of the first intermediate transfer members, thereby causing the final transfer member, each of the first intermediate transfer members, Each of these contact-type charging devices, each image carrier, each first intermediate transfer member, and the second in the relationship between the resistance value of the second intermediate transfer member and the voltage applied to the contact-type charging device. 2. A potential gradient is formed between the intermediate transfer member and the final transfer member.
6. The image forming apparatus according to 5. 20. Applying a voltage to the second intermediate transfer member and electrically floating each first intermediate transfer member between each grounded image carrier and a final transfer member, each first intermediate member The transfer member, the second intermediate transfer member, and the contact type charging device, the image bearing member, and the first member in the relationship between the resistance value of the image bearing member and the voltage applied to the contact charging device. 17. The image forming apparatus according to claim 16, wherein a potential gradient is formed between the intermediate transfer member, the second intermediate transfer member, and the final transfer member. 21. An image bearing member, a contact-type charging device that contacts and charges the image bearing member, an exposure device that forms a latent image on the charged image bearing member surface, and an image forming member formed on the image bearing member surface. A developing device that develops the latent image to form a toner image; an intermediate transfer member that contacts the image carrier to transfer the toner image formed on the surface of the image carrier; and a developing device that contacts the intermediate transfer member. A final transfer member for transferring a toner image on the surface of the intermediate transfer member onto a recording sheet, wherein the final transfer member is provided with a cleaning device and the intermediate transfer member is provided with a temporary holding member. When the image forming apparatus forms an image, the temporary holding member temporarily holds part or all of the remaining toner having the positive polarity and / or the opposite polarity. Apparatus, image carrier, intermediate transfer body Forming a potential gradient between the temporary holding member and the final transfer body, collecting remaining toner including the residual toner held on the temporary holding member on the final transfer body,
An image forming apparatus, wherein the residual toner collected on the final transfer body is collected by the cleaning device. 22. Four image carriers for cyan, magenta, yellow, and black are provided as image carriers, and each contact-type charging device and each image carrier that comes into contact with each image carrier are provided. 22. The image forming apparatus according to claim 21, wherein a potential gradient is formed between the transfer member, the intermediate transfer member, and the final transfer member. 23. Four image carriers for cyan, magenta, yellow, and black are provided as image carriers, and the intermediate transfer member is one of these four image carriers. A pair of first intermediate transfer member that contacts
Each pair of the first intermediate transfer member and the second intermediate transfer member that comes in contact with the final transfer member, each contact type charging device that contacts each image carrier, each image carrier, each first 22. The image forming apparatus according to claim 21, wherein a potential gradient is formed between the intermediate transfer member, the second intermediate transfer member, and the final transfer member. 24. A voltage is applied to the contact-type charging device, the intermediate transfer member, and the final transfer member, and the contact-type charging device, the image carrier,
24. The image forming apparatus according to claim 21, wherein a potential gradient is formed between the intermediate transfer member, the temporary holding member, and the final transfer member. 25. Applying a voltage to the final transfer member and electrically floating the intermediate transfer member between the image transfer member and a grounded image bearing member, thereby reducing the resistance values of the final transfer member, the intermediate transfer member, and the image bearing member. 24. A potential gradient is formed between the contact-type charging device, the image carrier, the intermediate transfer member, the temporary holding member, and the final transfer member in a relationship between the relationship and the voltage applied to the contact-type charging device. The image forming apparatus according to any one of the above. 26. The image forming apparatus according to claim 21, wherein the image carrier is provided with a temporary holding member for cleaning and temporarily holding residual toner remaining on the surface of the image carrier. 27. The image forming apparatus according to claim 21, wherein the temporary holding member is a roll-type or brush-type cleaning device capable of temporarily holding the remaining toner. 28. An image bearing member, a charging device for charging the surface of the image bearing member, an exposure device for forming a latent image on the charged surface of the image bearing member, and a latent image formed on the surface of the image bearing member. A developing device that develops to form a toner image, an intermediate transfer member that contacts the image carrier and transfers the toner image formed on the surface of the image carrier, and an intermediate transfer member that contacts the intermediate transfer member A final transfer member for transferring a toner image on the surface onto a recording sheet, wherein the intermediate transfer member is provided with a temporary holding member, and the final transfer member is provided with a cleaning device, The temporary holding member temporarily holds part or all of the remaining toner of the positive polarity and / or the opposite polarity during the image formation of the image forming apparatus, and the final transfer member and the intermediate transfer during the cleaning mode of the image forming apparatus. Between body and temporary holding member The remaining toner, including the residual toner temporarily held by the temporary holding member, is collected on a final transfer member, and the residual toner collected on the final transfer member is cleaned by the cleaning device. An image forming apparatus characterized by collecting. 29. The image forming apparatus according to claim 28, wherein the charging device is a contact type charging device. 30. The image forming apparatus according to claim 28, wherein the charging device is a non-contact type charging device. 31. The image forming apparatus according to claim 28, comprising four image carriers for cyan, magenta, yellow, and black as image carriers. 32. An image carrier comprising four image carriers for cyan, magenta, yellow, and black, and wherein the intermediate transfer member contacts two of the four image carriers. 29. The image forming apparatus according to claim 28, further comprising a pair of first intermediate transfer members, and a second intermediate transfer member in contact with the pair of first intermediate transfer member and the final transfer member. 33. A potential gradient is formed between the final transfer member, the intermediate transfer member, and the temporary holding member by applying a voltage to the intermediate transfer member, the temporary holding member, and the final transfer member.
3. The image forming apparatus according to any one of 2. 34. A voltage is applied between the final transfer member and a temporary holding member attached to the intermediate transfer member, and the intermediate transfer member located between the final transfer member and the temporary holding member is electrically floated. 33. A potential gradient is formed between the final transfer member, the intermediate transfer member and the temporary holding member in relation to the resistance values of the final transfer member, the intermediate transfer member and the temporary holding member. The image forming apparatus as described in the above. 35. The image forming apparatus according to claim 28, wherein the temporary holding member is a roll-type or brush-type cleaning device capable of temporarily holding the remaining toner.