JP2003215944A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus which is successively operated so as to stably perform excellent transfer by preventing the occurrences of the fluctuation of a transfer current and the electrification of a surface due to a resistance change because a state is changed with time by applying the bias voltage of the same polarity to an intermediate transfer body in the image forming apparatus possessing the intermediate transfer body using semiconductor rubber or semiconductive paint having conductivity by ionic conduction. <P>SOLUTION: The image forming apparatus possessing the intermediate transfer body using the semiconductor rubber or the semiconductive paint having the conductivity by the ionic conduction is provided with an electrification preventive device to apply the reverse bias voltage of a polarity reverse to that of bias voltage applied to a carrier removing unit by which surplus carrier is removed from a toner layer formed on the intermediate transfer body. <P>COPYRIGHT: (C)2003,JPO

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 having an intermediate transfer member using a semiconductive rubber or semiconductive paint having conductivity by ionic conduction, and a bias voltage of the same polarity is applied to the intermediate transfer member. The present invention relates to an image forming apparatus capable of stably performing good transfer by preventing a change in transfer current due to a resistance change and a charging of a surface due to a change in resistance due to application of a voltage. .

[0002]

2. Description of the Related Art FIG. 9 is a prior art diagram showing an overall configuration of an image forming apparatus. In the figure, the image forming apparatus includes developing units 54, 55, 56, 57 and an intermediate transfer member 51.
And the carrier removing unit 61 are the main components. The developing units 54, 55, 56, 57 are provided on the intermediate transfer member 51 in association with yellow / magenta / cyan / black. Further, the developing units 54, 5
Photosensitive drums and developing rollers are provided at 5, 56 and 57, respectively.

The developing roller is biased to a predetermined voltage and adheres toner to an exposed portion of the photosensitive drum in accordance with an electric field between the developing roller and the photosensitive drum to develop an electrostatic latent image on the photosensitive drum to form an image. To form. Liquid toner is supplied onto the developing roller from a toner reservoir. As a result, the liquid toner is applied on the developing roller in a predetermined layer thickness.

The intermediate transfer member 51 is formed by coating a semi-conductive rubber or semi-conductive paint having conductivity due to ionic conduction, and is attached to the photosensitive drum according to an electric field between the intermediate transfer member 51 and each photosensitive drum. Transfer the toner. As a result, the four-color toner image developed on each photosensitive drum is
While the intermediate transfer body 51 is rotated once, the intermediate transfer body 5 is sequentially rotated.
The carrier liquid is removed by the carrier removing unit 61 from the four color images superimposed on one another.

Thereafter, the four-color image is transferred to the print medium at the contact portion with the print medium by using the pressure roller 52, and then fixed through a fixing unit (not shown).

The carrier removing unit 61 is provided with a bias applying means for applying a bias voltage in a direction of pressing each color image on the intermediate transfer body 51, and a collecting means for collecting oil. It is configured to come into contact with the transfer body 51 and remove excess carriers from the toner layer formed on the intermediate transfer body 51.

A carrier removal process is required when a mechanism using a non-volatile, high-viscosity, high-concentration liquid toner is adopted. At that time, the carrier removing roller constituting the carrier removing unit has a direct current of about 2 kV to 3 kV. High bias voltage is applied. At this time, the intermediate transfer member is in a state in which a large positive bias voltage of about 400 V is applied, and the ion conductive intermediate transfer member undergoes polarization of ions, and the resistance value changes so that the resistance value becomes high. As a result, the surface becomes easily charged.

When the surface of the intermediate transfer member is charged after applying a bias voltage to the carrier removing unit, the primary transfer is performed from the photosensitive drum to the intermediate transfer member, and the secondary transfer is performed from the intermediate transfer member to the printing medium. As a result, there is a problem that a stable transferred image cannot be obtained. Therefore, it is necessary to prevent the polarization of ions and keep the surface of the intermediate transfer member in a non-charged state.

To solve such a problem, conventional examples are Japanese Patent Laid-Open Nos. 9-114273 and 10-48.
No. 914 publication is available. The contents disclosed in these patent publications are that the resistance value of a member such as a roller or a belt to which conductivity is imparted by ionic conductivity is gradually changed by application of a DC bias voltage, There is a method in which a bias voltage of opposite polarity is applied to cancel a change in resistance value. In the bias voltage application, a DC voltage is applied to the member to be charged during charging, and a DC voltage having the opposite polarity to the DC voltage at the time of charging is applied to the member to be charged during non-charging. It is a thing.

That is, the DC voltage applied during charging and the DC voltage of opposite polarity applied during non-charging are switched and applied to the member to be charged. Therefore, when switching the DC voltage applied to the charged member, it is impossible to continuously apply the DC voltage of the opposite polarity to the charged member. When it increases, it becomes impossible to suppress the change in resistance value, and continuous operation becomes impossible.

[0011]

As described above, the conventional techniques have the following problems.

In an image forming apparatus having an intermediate transfer member using a semi-conductive rubber or semi-conductive paint having conductivity due to ionic conduction, a DC voltage of opposite polarity is continuously applied to the intermediate transfer member. Therefore, if the number of print media increases, it becomes impossible to suppress the change in resistance value, which makes continuous operation impossible.

An object of the present invention is to apply a bias voltage of the same polarity to an intermediate transfer body in an image forming apparatus having an intermediate transfer body using a semiconductive rubber or a semiconductive paint having conductivity by ionic conduction. As a result, it is possible to provide an image forming apparatus capable of continuous operation, which can prevent the transfer current from changing due to resistance change and the surface from being charged due to a change in state over time, and can perform stable stable transfer. To provide.

[0014]

In order to solve the above problems, the present invention takes the following means.

In an image forming apparatus having an intermediate transfer member using a semi-conductive rubber or semi-conductive paint having conductivity by ionic conduction, a reverse bias voltage having a reverse polarity to the bias voltage applied to the carrier removing unit is applied. It is applied to the intermediate transfer member.

By adopting the above-mentioned means, it is possible to suppress the change of the resistance value such that the resistance value of the intermediate transfer member becomes high by eliminating the polarization of the ions due to the bias voltage applied to the carrier removal unit, and to apply it to the carrier removal unit. To provide an image forming apparatus capable of stably performing good transfer by preventing the surface of the intermediate transfer member from being charged after applying the bias voltage.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention has the following embodiments.

As shown in FIG. 1, a toner layer formed on the intermediate transfer body 1 in an image forming apparatus having an intermediate transfer body using a semiconductive rubber or a semiconductive paint having conductivity by ionic conduction. Carrier removing unit (carrier removing roller 11
The antistatic device 20 is provided for applying a reverse bias voltage 26 having a polarity opposite to that of the bias voltage 25 applied to a) to the intermediate transfer member 1.

With the above-described configuration, the reverse bias voltage of the intermediate transfer member is continuously applied by applying the amount corresponding to the integrated amount of the bias voltage applied by the bias voltage applied to the carrier removing unit. Charge is suppressed. That is, by eliminating the polarization of ions due to the bias voltage applied to the carrier removal unit, the resistance change of the intermediate transfer member such as the resistance value becoming high is suppressed, and even after the bias voltage is applied to the carrier removal unit, the intermediate transfer is performed. (EN) Provided is an image forming apparatus capable of keeping a body surface in a non-charged state, and capable of stable and good transfer, and capable of continuous operation.

Further, as shown in FIG. 4, in the antistatic device 20, the process of transferring the intermediate transfer member 1 to the print medium by one rotation is completed, and the photosensitive drum is transferred to the intermediate transfer member 1 in the next process. Install by the time the transfer process begins.

By adopting the above-mentioned embodiment, for example, the antistatic device is installed downstream of the pressure roller installed opposite to the intermediate transfer member provided for transferring to the print medium, and the intermediate transfer member is installed. To be able to eliminate the polarization of the ions every turn. That is, since the polarization of the ions of the intermediate transfer member can be canceled by the process of one round, images can be continuously formed on the print medium. This suppresses a change in resistance value such that the resistance value of the intermediate transfer member increases without lowering the throughput.

Further, the antistatic device 20 applies a reverse bias voltage 26 applied to the intermediate transfer body 1 to the carrier removing units as a bias voltage larger in absolute value than the bias voltage applied to each carrier removing unit.

In order to suppress the resistance value change such that the resistance value of the intermediate transfer member becomes high by adopting the above-mentioned form, the reverse amount equivalent to the integrated amount of the bias current applied from the carrier removing unit to the intermediate transfer member is suppressed. It is necessary to apply a bias current to the intermediate transfer member, but by applying a reverse bias voltage whose absolute value is larger than the bias voltage applied to each carrier removal unit, the current value per line on the antistatic device side Since the total current is made the same by increasing
It is possible to reduce the number of places to apply reverse bias voltage,
It is possible to save space when installing an antistatic device.

Further, as shown in FIG. 1, the antistatic device 20 contacts the intermediate transfer body 1 by using a conductive or semiconductive roller made of a material softer than the hardness of the intermediate transfer body 1. While being installed, a reverse bias voltage 26 having a reverse polarity to the bias voltage applied to the carrier removing unit (carrier removing roller 11a) is applied to the roller.

With the above-described configuration, for example, by using a sponge roller as the soft roller, the nip width formed by the intermediate transfer body and the soft roller can be made large, so that the reverse bias voltage is intermediately transferred. By increasing the time of application to the body, the total current can be increased, the number of locations to which the reverse bias voltage is applied can be reduced, and space can be saved when the antistatic device is installed.

Further, as shown in FIG. 2, the antistatic device 20 is installed in a non-contact manner with the intermediate transfer member 1 by using a conductive or semi-conductive wire 20a, and a carrier removing unit (carrier removing roller). Reverse bias voltage 2 having a reverse polarity to the bias voltage 25 applied to 11a).
6 is applied to the wire 20a.

By adopting the above-mentioned configuration, when the antistatic device is composed of rollers, the place where the rollers are installed is limited to the downstream of the pressure roller, but the wires are installed without contact with the intermediate transfer member. Therefore, the installation location is not limited. For example, by arranging each of the carrier removing units installed between the developing units on the downstream side, it is possible to increase the degree of freedom in installing the antistatic device and save space.

Further, as shown in FIG. 3, the antistatic device 20 includes a cleaning mechanism which comes into contact with the intermediate transfer member 1 to scrape off the excess toner.

With the above-described configuration, the roller antistatic device having a cleaning mechanism for scraping off the excess toner remaining on the intermediate transfer body scrapes off the excess toner on the intermediate transfer body after passing through the pressure roller. Since it also has a function, cleaning of the intermediate transfer member and prevention of charging of the intermediate transfer member can be performed at the same time.

[0030]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A typical embodiment according to the present invention will be described with reference to FIGS. In the following, the same parts are denoted by the same reference numerals, and detailed description thereof may be omitted.

FIGS. 1 and 4 are views showing an embodiment of the present invention, FIG. 1 is a schematic view showing a main part, and FIG. 4 is a view showing an overall configuration of an image forming apparatus.

In FIG. 4, the image forming apparatus mainly includes developing units 4, 5, 6, and 7, an intermediate transfer body 1, a carrier removing unit 11, a pressure roller 2, and an antistatic device 20. I am trying.

The developing units 4, 5, 6, 7 are provided on the intermediate transfer member 1 in association with yellow / magenta / cyan / black. Further, the developing units 4, 5, 6,
7 is provided with a photosensitive drum and a developing roller, respectively. The photosensitive drum, the developing roller, and the pressure roller 2 have the same configurations as those in FIG. 9 described above, and detailed description thereof will be omitted.

The intermediate transfer member 1 is formed by coating a semi-conductive rubber or semi-conductive paint having conductivity due to ionic conduction, and is attached to the photosensitive drum according to the electric field between each photosensitive drum. Transfer the toner. by this,
The four-color toner images developed on the respective photosensitive drums are sequentially superposed on the intermediate transfer body 1 while the intermediate transfer body 1 is rotated once, and the four-color color image is transferred to the carrier liquid by the carrier removing unit 11. Are removed.

The carrier removing unit 11 presses the liquid toner against the intermediate transfer member 1 to remove only the silicone oil, and bias applying means for applying a bias voltage 25 in the direction of pressing each color image against the intermediate transfer member 1. When,
For example, a carrier removing roller 11a provided with a collecting means (not shown) for collecting oil is brought into contact with the intermediate transfer body 1 to remove excess carrier from the toner layer formed on the intermediate transfer body 1. .

In FIG. 1, the antistatic device 20 is for making the surface of the intermediate transfer member 1 uncharged after applying the bias voltage 25 to the carrier removing roller 11a.
A reverse bias voltage 2 having a polarity opposite to that of the bias voltage 25 applied to the carrier removing roller 11a for removing excess carriers from the toner layer formed on the intermediate transfer member 1.
6 is applied to the intermediate transfer member 1.

The reverse bias voltage 26 is continuously applied in an amount corresponding to the integrated amount of the bias voltage applied by the bias voltage 25 applied to the carrier removing roller 11a, whereby the charging of the intermediate transfer member 1 is suppressed. .

That is, by eliminating the polarization of ions due to the bias voltage 25 applied to the carrier removing roller 11a, a change in the resistance value such that the resistance value of the intermediate transfer member 1 becomes high is suppressed, and the bias voltage is applied to the carrier removing roller 11a. Even after application, the surface of the intermediate transfer member 1 can be kept in a non-charged state, thereby providing an image forming apparatus capable of stable continuous good transfer and capable of continuous operation. It is a thing.

As shown in FIG. 4, the antistatic device 20.
It is desirable that the intermediate transfer member 1 is installed by the time when the process of transferring the intermediate transfer member 1 to the print medium is completed and the process of transferring the photosensitive drum to the intermediate transfer member 1 is started in the next process. For example, the antistatic device 20 is installed downstream of the pressure roller 2 which is installed so as to face the intermediate transfer member provided for transferring to the print medium.

With this configuration, the intermediate transfer member 1 can eliminate the polarization of the ions for each rotation, that is, the polarization of the ions of the intermediate transfer member 1 can be canceled in the process of one rotation. Images can be continuously formed on the print medium. This suppresses a change in the resistance value such that the resistance value of the intermediate transfer body 1 increases without lowering the throughput.

Further, it is desirable that the antistatic device 20 applies a reverse bias voltage 26 applied to the intermediate transfer member 1 to a bias voltage larger in absolute value than the bias voltage 25 applied to each carrier removing roller 11a.

With this configuration, in order to suppress a change in the resistance value such that the resistance value of the intermediate transfer body 1 becomes high, the reverse bias equivalent to the integrated amount of the bias current applied to the intermediate transfer body 1 from the carrier removing roller 11a is suppressed. Current is transferred to the intermediate transfer body 1
Need to be applied to each carrier removal roller 1
By applying a reverse bias voltage whose absolute value is larger than the bias voltage applied to 1a, the current value per one on the antistatic device side is increased and the total current is made the same.
It is possible to reduce the number of places to apply reverse bias voltage,
A space can be saved when the antistatic device 20 is installed.

Further, as shown in FIG. 1, the antistatic device 20 contacts the intermediate transfer member 1 by using a conductive or semiconductive roller made of a material softer than the hardness of the intermediate transfer member 1. It is desirable that the reverse bias voltage 26 having a polarity opposite to that of the bias voltage applied to the carrier removing roller 11a is applied to the roller while being installed. For example, a sponge roller can be used as the soft roller. In addition, the antistatic device 20
The rotation direction of the roller constituting the roller is rotated so that the contact surface moves in the forward direction at the contact portion with the intermediate transfer member 1.

With this configuration, the nip width formed by the intermediate transfer member 1 and the soft roller can be increased, so that by increasing the time for applying the reverse bias voltage 26 to the intermediate transfer member 1, the total current is increased. Can be increased, the number of locations to which the reverse bias voltage is applied can be reduced, and space can be saved when the antistatic device 20 is installed.

2 and 5 are views showing an embodiment of the present invention, FIG. 2 is a schematic view showing a main part, and FIG. 5 is a view showing the entire structure of the image forming apparatus.

In FIG. 5, the image forming apparatus mainly includes developing units 4, 5, 6, and 7, an intermediate transfer member 1, a carrier removing unit 11, a pressure roller 2, and an antistatic device 20. I am trying. The configuration other than the antistatic device 20 is the same as that in FIG. 4 described above, and detailed description thereof will be omitted.

The antistatic device 20 keeps the surface of the intermediate transfer member 1 from being charged after the bias voltage 25 is applied to the carrier removing roller 11a, and it is redundant from the toner layer formed on the intermediate transfer member 1. A reverse bias voltage 26 having a polarity opposite to that of the bias voltage 25 applied to the carrier removing roller 11a for removing the carrier is applied to the intermediate transfer member 1.

The antistatic device 20 applies a reverse bias voltage 26 by corona discharge by a corotron, and is composed of a conductive or semiconductive wire 20a and a shield 20b. It is used to set the intermediate transfer member 1 in a non-contact manner and to apply a reverse bias voltage 26 having a reverse polarity to the bias voltage 25 applied to the carrier removing roller 11a to the wire 20a.

With this structure, when the antistatic device 20 is composed of rollers, the place where the rollers are installed is limited to the downstream of the pressure roller 2 (see FIG. 4), but as shown in FIG. Since 20a is installed without contact with the intermediate transfer body 1, the installation place is not limited. For example, by disposing the carrier removing units 11 installed between the developing units 4, 5, 6, and 7 in the downstream of each of them, the antistatic device 2
It is possible to increase the degree of freedom of installation of 0 and save space.

FIG. 3 shows a schematic diagram of an embodiment of the present invention.

In the figure, the antistatic device 20 is installed in contact with the intermediate transfer member 1 using a conductive or semiconductive roller made of a material softer than the hardness of the intermediate transfer member 1. A cleaner blade 3 that scrapes off excess toner that could not be transferred by contacting the roller.
1 and a toner collecting unit 3 for collecting the scraped excess toner
2 and. The antistatic device 20 includes a cleaning mechanism that comes into contact with the intermediate transfer member 1 to scrape off the excess toner, and a bias voltage in the peeling direction is applied.

That is, the antistatic device 20 applies to the roller a reverse bias voltage 26 having a reverse polarity to the bias voltage applied to the carrier removing roller 11a.
For example, a sponge roller can be used as the soft roller. The rotation direction of the roller forming the antistatic device 20 is such that the contact surface moves in the opposite direction at the contact portion with the intermediate transfer body 1.

With this configuration, the antistatic device 20 by means of a roller which also serves as a cleaning mechanism for scraping off the excess toner remaining on the intermediate transfer body 1 scrapes off the excess toner on the intermediate transfer body 1 after passing through the pressure roller 2. Since it also has a function, cleaning of the intermediate transfer member 1 and
It is possible to simultaneously perform the antistatic treatment.

Next, the effect of preventing charging of the intermediate transfer member by applying a reverse bias voltage having a reverse polarity to the bias voltage applied to the carrier removing unit to the intermediate transfer member will be described.

FIG. 6 is an explanatory diagram of an embodiment of the present invention.

In Experiment No. 1, when only a positive bias voltage is applied from the carrier removing roller in the initial state where no bias voltage is applied to the intermediate transfer member, the charging potential of the intermediate transfer member immediately rises.

In Experiment NO2, after Experiment NO1, if only the negative bias voltage is applied from the roller constituting the antistatic device, it is understood that the intermediate transfer member is difficult to be charged to the negative bias voltage.

In Experiment NO3, after Experiment NO2, if only a positive bias voltage is applied from the carrier removing roller as in Experiment NO1, the intermediate transfer body is in a state of being difficult to be charged after the application of the negative bias voltage. I understand.

7 and 8 are explanatory views of an embodiment of the present invention.

In Experiment No. 4, the relationship between the application time when only the positive bias voltage is applied from the carrier removing roller and the charging potential of the intermediate transfer member is shown.

In Experiment NO5, when a positive bias voltage is applied five times from the carrier removing roller every time a negative bias voltage is applied once from the roller of the antistatic device, as compared with Experiment NO4, the charge rise of the intermediate transfer member is increased. Is suppressed.

In Experiment NO6, when the nip width formed by the roller of the antistatic device for applying the negative bias voltage in Experiment NO5 and the intermediate transfer member is increased, the negative current value increases, and the intermediate transfer member is subjected to Experiment NO5. Is more difficult to charge than.

In Experiment NO7, when the negative bias voltage was raised in Experiment NO6, the current value was further increased, and the increase in charge of the intermediate transfer member was suppressed.

In Experiment No. 8, the same effect was obtained when a negative bias voltage was applied by the corotron.

[0065]

According to the present invention, the following effects can be expected.

Even in an image forming apparatus having an intermediate transfer member coated with a semiconductive rubber or a semiconductive paint having conductivity due to ionic conduction, the intermediate transfer member with time changes due to the bias voltage applied to the carrier removing unit. It is possible to suppress such a change in resistance value and keep the surface of the intermediate transfer member from being charged even after applying a bias voltage to the carrier removing unit. Accordingly, it is possible to provide an image forming apparatus capable of continuous operation capable of stably performing good transfer.

Further, for example, the antistatic device is installed downstream of the pressure roller installed opposite to the intermediate transfer member provided for transferring to the print medium, so that the intermediate transfer member is ionized once per revolution. Be able to eliminate the polarization of. That is, since the polarization of the ions of the intermediate transfer member can be canceled by the process of one round, images can be continuously formed on the print medium. As a result, it is possible to suppress a change in the resistance value such that the resistance value of the intermediate transfer member increases without lowering the throughput.

Further, the antistatic device applies a reverse bias voltage applied to the intermediate transfer member to the carrier removal unit by a bias voltage larger in absolute value than the bias voltage applied to each carrier removing unit. Since the current value per book is increased to make the total current the same,
It is possible to reduce the number of places to apply reverse bias voltage,
It is possible to save space when installing an antistatic device.

Further, the antistatic device is installed in contact with the intermediate transfer member by using a conductive or semiconductive roller made of a material softer than the hardness of the intermediate transfer member, and installed in the carrier removing unit. By applying a reverse bias voltage having a polarity opposite to that of the applied bias voltage to the roller, it is possible to obtain a large nip width formed by the intermediate transfer body and the soft roller. Therefore, the reverse bias voltage is applied to the intermediate transfer body. By increasing the time of applying the voltage to the device, the total current can be increased, the number of locations to which the reverse bias voltage is applied can be reduced, and space can be saved when the antistatic device is installed.

Further, the antistatic device is installed in a non-contact manner with the intermediate transfer member using a conductive or semi-conductive wire, and has a reverse bias voltage having a reverse polarity to the bias voltage applied to the carrier removing unit. Is applied to the wire without contacting the intermediate transfer member, the installation location is not limited. For example, by arranging each of the carrier removing units installed between the developing units on the downstream side, it is possible to increase the degree of freedom in installing the antistatic device and save space.

Further, since the antistatic device using the roller also has a function of scraping off the excess toner on the intermediate transfer body after passing through the pressure roller, the intermediate transfer body is cleaned and the intermediate transfer body is prevented from being charged. Can be done at the same time.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an example of the present invention.

FIG. 2 is a schematic view of an example of the present invention.

FIG. 3 is a schematic view of an example of the present invention.

FIG. 4 is a diagram of an embodiment of the present invention.

FIG. 5 is a diagram of an embodiment of the present invention.

FIG. 6 is an explanatory diagram of an example of the present invention.

FIG. 7 is an explanatory diagram of an example of the present invention.

FIG. 8 is an explanatory diagram of an example of the present invention.

FIG. 9 is a diagram of the prior art.

[Explanation of symbols] 1: Intermediate transfer body 11: Carrier removal unit 11a: Carrier removing roller 20: Antistatic device (Corotron) 20a: Wire 20b: shield 25: Bias voltage 26: Reverse bias voltage 31: Cleaner blade 32: Toner collection unit

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kazushi Terashima             At 98 Unoke-nu, Unoki-cho, Kawakita-gun, Ishikawa Prefecture             2 PFU Co., Ltd. (72) Inventor Masataka Takahata             At 98 Unoke-nu, Unoki-cho, Kawakita-gun, Ishikawa Prefecture             2 PFU Co., Ltd. (72) Inventor Hideaki Shibata             At 98 Unoke-nu, Unoki-cho, Kawakita-gun, Ishikawa Prefecture             2 PFU Co., Ltd. (72) Inventor Norihiro Yamasaku             At 98 Unoke-nu, Unoki-cho, Kawakita-gun, Ishikawa Prefecture             2 PFU Co., Ltd. (72) Inventor Eiji Yamaguchi             At 98 Unoke-nu, Unoki-cho, Kawakita-gun, Ishikawa Prefecture             2 PFU Co., Ltd. F-term (reference) 2H200 FA17 FA18 GA12 GA23 GA43                       GA47 HA03 HB12 HB22 JA08                       JC02 JC11 JC12 JC15 JC18                       JC19 LB03 LB15 LB35 LB38                       LB39 MA04 MA08 MA20 MB01                       MB02 NA02 NA13 PA03 PA18                       PA22                 5G067 AA65 CA10

Claims (6)

[Claims] 1. An image forming apparatus having an intermediate transfer member using a semiconductive rubber or semiconductive paint having conductivity by ionic conduction, and removing excess carriers from a toner layer formed on the intermediate transfer member. An image forming apparatus comprising: an antistatic device that applies a reverse bias voltage having a polarity opposite to that of the bias voltage applied to the carrier removal unit for performing the operation to the intermediate transfer member. 2. The antistatic device is provided until the process of transferring the intermediate transfer member to the print medium by one rotation is completed and the process of transferring the photosensitive drum to the intermediate transfer member is started in the next process. The image forming apparatus according to claim 1, wherein the image forming apparatus is installed in the image forming apparatus. 3. The antistatic device applies a reverse bias voltage applied to the intermediate transfer member to a bias voltage which is larger in absolute value than a bias voltage applied to each carrier removing unit. The image forming apparatus described. 4. The antistatic device is installed in contact with the intermediate transfer member by using a conductive or semi-conductive roller made of a material softer than the hardness of the intermediate transfer member, and is installed in a carrier removing unit. The image forming apparatus according to claim 1, wherein a reverse bias voltage having a polarity opposite to that of the applied bias voltage is applied to the roller. 5. The antistatic device is installed in a non-contact manner with an intermediate transfer member using a conductive or semi-conductive wire, and has a reverse bias voltage having a reverse polarity to the bias voltage applied to the carrier removing unit. The image forming apparatus according to claim 1, wherein is applied to the wire. 6. The image forming apparatus according to claim 1, wherein the antistatic device includes a cleaning mechanism that scrapes off excess toner by contacting the intermediate transfer member.