JPH05313526A - Image forming device - Google Patents

Abstract

PURPOSE:To provide an image forming device capable of forming a high quality image which is stable over a long period of time by carrying out the optimum filming layer removal which meets all applied conditions, and preventing a decrease in transfer efficiency, wrapping of a cleaning blade, etc., resulting from the formation of the filming layer. CONSTITUTION:The image forming device provided with a means which electrostatically transfers a toner image on a first image carrier 2 to the surface of a second image carrier 3 and with the second image carrier 3 which carries the transferred toner image and is driven to rotate is further provided with a potential sensor 15 which detects the potential of the electrification on the second image carrier 3 after the toner image on the first image carrier 2 is electrostatically transferred to the surface of the second image carrier 3; a storage circuit for storing the detection value of the potential sensor 15; a comparator circuit where the output of the storage circuit is inputted and a plurality of detection values are compared with each other; and a means for detecting changes in resistance value of the second image carrier 3 and electrostatic capacity by the output of the comparator circuit.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image bearing member and a cleaning member which comes into contact with the image bearing member to remove residual toner.
The present invention relates to an image forming apparatus such as a copying machine, a printer, or a fax machine, which uses an electrophotographic process and has a rubbing member that abuts an image carrier and polishes the image carrier.

[0002]

2. Description of the Related Art Most of the conventional image forming apparatus 1 using an electrophotographic process is the same as that of the embodiment of the present invention, so that it will be described with reference to FIG. The toner adheres to the first image carrier 2 which is a photoconductor and the second image carrier 3 which is an intermediate transfer body, and the member for cleaning the toner by the next image forming cycle presses the edge of urethane rubber. A cleaning blade 5 for scraping off the toner and a fur brush using a bristle brush are used. However, the toner melted by heat or pressure may cause the toner to melt on the first image carrier 2.
Alternatively, when it occurs in the second image carrier 3, it cannot be removed by the cleaning blade 5 alone, and the filming layer is gradually formed, so that the transfer performance is deteriorated and the image quality is deteriorated. Particularly, in the case of the double transfer method using the second image carrier 3, the transfer efficiency is greatly reduced even with a slight filming. Further, when a filming layer is formed on those image bearing members, the friction coefficient between the blade and the image bearing member increases. Therefore, when the cleaning blade 5 is provided by using the counter blade method, the cleaning blade 5 is caught. Easier to do. When the second image carrier 3 is a belt member stretched by the driving roller 8 and the driven roller 9,
The drive roller 8 idles due to an increase in the frictional force between the cleaning blade 5 and the second image carrier 3. As a measure to eliminate this, the rubbing member 10 is rubbed to remove the filming layer. Also, there is a system in which the rubbing member 10 rubs the second image carrier 3 once every several copies. Reference numeral 11 is a backup roller, and 12 is an earth roller.

[0003]

In the image forming apparatus as described above, when the filming layer of the second image carrier is thus removed by the rubbing member, the second image carrier is rubbed too much. If the second image bearing member has a short life and the rubbing member is set to rub the second image bearing member once every several copies, use of a copying machine Since the generation state of filming changes depending on the conditions and the like, there is a problem that the optimum filming layer cannot be removed in accordance with all use conditions.

Therefore, an object of the present invention is to eliminate the problems of the conventional image forming apparatus as described above, remove the filming layer optimally for all conditions of use, and transfer the filming film by generating it. An object of the present invention is to provide an image forming apparatus capable of forming stable high-quality images for a long period of time by preventing the efficiency from being lowered and the cleaning blade from being caught.

[0005]

In order to achieve the above-mentioned object, the present invention provides a toner image on a first image carrier on a second image carrier. In the image forming apparatus having a second image bearing member that rotatably drives the toner image that has been transferred and that carries the transferred toner image.
A potential sensor that detects a charging potential on the second image carrier after the toner image on the image carrier is electrostatically transferred onto the second image carrier, and a memory that stores a detection value of the potential sensor. A circuit, and an output of the storage circuit is input, and has a comparison circuit for comparing a plurality of detection values, the output of the comparison circuit,
It is provided with a means for detecting a change in the resistance value and the capacitance of the second image carrier. According to a second aspect of the present invention, in the first aspect of the present invention, the toner image on the first image carrier is electrostatically transferred onto the second image carrier, upstream of the second image carrier in the transfer nip portion. A bias roller is arranged on the downstream side so as to form a transfer nip portion, a potential sensor for detecting the charging potential of the second image carrier is provided in the transfer nip portion, and the potential rise time is determined by the output of the potential sensor. It is provided with a means for detecting. The invention of claim 3 relates to claim 1
Alternatively, in the invention of claim 2, a rubbing member for polishing the surface of the second image carrier is provided so as to be able to come into contact with and separate from the second image carrier, and means for controlling the operating time of the rubbing member is provided by the output of the comparison circuit. It is a thing. According to a fourth aspect of the invention, in the first or second aspect of the invention, a cleaning member for removing the residual toner on the second image carrier is provided so that it can be brought into contact with and separated from the second image carrier, and the cleaning member is used as the second image carrier. A means for changing the pressure applied to the body by the output of the comparison circuit is provided.
According to a fifth aspect of the present invention, in the fourth aspect of the present invention, the temperature detection device detects the temperature of the second image carrier or the cleaning member, and the humidity detection device detects the humidity in the vicinity of the second image carrier. A means for adjusting the amount of change in the pressing force for pressing the cleaning member against the second image carrier is provided by the outputs of the temperature detecting device and the humidity detecting device. Claim 6
In the invention according to any one of claims 1 to 5, when the sliding member rubs the second image carrier, the cleaning member is released from the second image carrier to release the second image carrier.
It is provided with means for rotating the image carrier. According to a seventh aspect of the present invention, in any one of the first to fifth aspects, the rubbing member is carried on the first image carrier on the downstream side of the cleaning member with respect to the rotation direction of the second image carrier. The toner image is placed upstream of the portion where the toner image is transferred to the second image carrier, and when the cleaning member is in contact with the second image carrier, the output of the comparison circuit causes the resistance value of the second image carrier to change. And the change in capacitance is detected, and by the detection output,
It is provided with means for bringing the rubbing member into contact with the second image carrier to perform the rubbing operation. The invention of claim 8 relates to claim 1.
In any one of the inventions 1 to 7, the cleaning member is an elastic blade that comes into contact with the rotation direction of the second image carrier in the counter direction. The invention of claim 9 is the brush roller according to any one of claims 1 to 7, wherein the rubbing member is made of a metal loop fiber.
The invention of claim 10 is the brush roller according to any one of claims 1 to 7, wherein the rubbing member is made of a loop fiber of a conductive resin.

[0006]

According to the present invention as described above, in the image forming apparatus as described above, the toner image on the first image carrier is electrostatically transferred onto the second image carrier. Potential sensor that detects the charging potential on the second image carrier after the storage, a storage circuit that stores the detection value of the potential sensor, and a comparison circuit that receives the output of the storage circuit and compares a plurality of detection values. And a means for detecting a change in the resistance value and the electrostatic capacity of the second image carrier by the output of the comparison circuit, and a change in the resistance value and the electrostatic capacity of the second image carrier. To detect. According to a second aspect of the present invention, in the first aspect of the present invention, the toner image on the first image carrier is electrostatically transferred onto the second image carrier, upstream of the second image carrier in the transfer nip portion. A bias roller is arranged on the downstream side so as to form a transfer nip portion, a potential sensor for detecting the charging potential of the second image carrier is provided in the transfer nip portion, and the potential rise time is determined by the output of the potential sensor. A means for detecting is provided to detect the rise time of the potential at the transfer nip portion. According to a third aspect of the present invention, in the first or second aspect of the present invention, a rubbing member for polishing the surface of the second image carrier is provided so that it can be brought into contact with and separated from the second image carrier, and the rubbing member is output by the comparison circuit. And a means for controlling the operation time of (1) to perform an optimum filming removal operation in accordance with the amount of filming generated. According to a fourth aspect of the invention, in the first or second aspect of the invention, a cleaning member for removing the residual toner on the second image carrier is provided so that it can be brought into contact with and separated from the second image carrier, and the cleaning member is used as the second image carrier. A means for changing the pressure applied to the body by the output of the comparison circuit is provided, and the drive roller of the second image carrier does not idle due to an increase in the frictional force between the cleaning member and the second image carrier. According to a fifth aspect of the present invention, in the fourth aspect of the present invention, the temperature detection device detects the temperature of the second image carrier or the cleaning member, and the humidity detection device detects the humidity in the vicinity of the second image carrier. The temperature detection device and the humidity detection device are provided with means for adjusting the amount of change in the pressing force of the cleaning member brought into pressure contact with the second image carrier, and the optimum minimum pressing force corresponding to the environmental conditions. To set. According to a sixth aspect of the present invention, in any one of the first to fifth aspects, the second image is generated by releasing the cleaning member from the second image carrier during the operation of polishing the second image carrier by the rubbing member. The cleaning member is provided with a means for rotating the carrier so that the cleaning member is not loaded. The invention of claim 7 is the invention of any one of claims 1 to 5,
The rubbing member is arranged downstream of the cleaning member with respect to the rotation direction of the second image carrier and upstream of the portion where the toner image carried on the first image carrier is transferred to the second image carrier. Then, when the cleaning member is in contact with the second image carrier, the output of the comparison circuit detects a change in the resistance value and the capacitance of the second image carrier, and the detection output detects the rubbing member. Means for contacting the second image carrier to perform a rubbing operation is provided, and filming is removed even during the image forming operation. According to an eighth aspect of the present invention, in any one of the first to seventh aspects, the cleaning member is an elastic blade that abuts in the counter direction with respect to the rotation direction of the second image carrier, so that one blade can be used to ensure Clean the residual toner. According to a ninth aspect of the present invention, in the invention according to any one of the first to seventh aspects, the rubbing member removes filming with a brush roller of metal loop fibers. Claim
According to a tenth aspect of the invention, in the invention according to any one of the first to seventh aspects, the rubbing member removes filming with a brush roller of loop fibers made of a conductive resin.

[0007]

Embodiments of the present invention will be described below with reference to the accompanying drawings. In this embodiment shown in the drawings, the same parts as those of the conventional one are referred to by the same reference numerals and the description thereof will be omitted, and mainly different parts will be described.

An embodiment of the present invention is shown in FIGS. Figure 1
In this embodiment shown in FIG. 2, the first bias roller 13 and the second bias roller 14 are stretched and brought into contact with the first image carrier 2 to form a nip portion to provide the second image carrier 3. A potential sensor 15 for measuring the charging potential of the second image carrier 3 is provided in the vicinity of the first bias roller 13 and the second bias roller 14 in the vicinity of the second image carrier 3. On the upstream side of the second bias roller 14, a rubbing member 10 for removing filming of the second image carrier 3 and an earth roller 12 facing the rubbing member 10 via the second image carrier. The rubbing member 10 is provided so as to be able to come into contact with and separate from the second image carrier 3 by a contacting / separating mechanism (not shown), and a cleaning blade 5 for scraping off the residual toner of the second image carrier 3 is provided upstream of the rubbing member 10. .. First bias roller
A bias voltage of about 1000 V is applied to 13 and the second bias roller 14. A temperature sensor 22 that measures the temperature of the second image carrier 3 and a humidity sensor 23 that measures the humidity in the image forming apparatus 1 are provided near the second image carrier 3.

This embodiment comprises a control device shown in FIG. The control device includes a storage circuit 16 and a rise time detection circuit 17 to which the output of the potential sensor 15 is input, and a comparison circuit 18 to which the outputs of the storage circuit 16 and the rise time detection circuit 17 are input.
And a control circuit 19 to which the output of the comparison circuit 18 is input, and a blade contact cam motor 20 and a rubbing member drive motor 21 driven by the output of the control circuit 19.

The cleaning device of this embodiment has a mechanism capable of adjusting the pressure applied to the cleaning blade 5. The pressing force is adjusted by transmitting the displacement amount of the pressure spring 7 to the cleaning blade 5 via the holder 4 using the pressing force adjusting cam 6. At this time, the rotation amount of the pressurizing force adjusting cam 6 is controlled by a control circuit (not shown) to which the detected values of the temperature sensor 22 and the humidity sensor 23 are input, and the contact pressure is adjusted stepwise.

In this embodiment, the second image carrier 3 which has been neutralized by the ground roller 12 of the second image carrier 3 is charged by the first and second bias rollers 13 and 14 for image transfer. When the bias voltage is constant, the rise time of the potential of the second image carrier 3 is determined by the time constant τ of the second image carrier 3. (Τ = RC, R = resistance value of the second image carrier 3, C = capacitance of the second image carrier 3) For example,
The bias voltage-total current characteristic (V
As a result of measuring the −I characteristic) and the rise time of the potential, the result is as shown in FIG. 3, and the rise time sharply increases as the resistance value of the second image carrier 3 increases. When filming occurs on the second image carrier 3, since the dielectric layer is formed on the second image carrier 3, the time constant τ increases and the rise time of the potential is delayed. Therefore, the potential sensor 15 can be used to detect the occurrence of filming by measuring the rising time from the start of the application of the bias potential to the saturation of the potential of the second image carrier 3. However, since the resistance value varies depending on the individual second image carriers 3, the initial value is measured when the second image carrier 3 is replaced, and the rising time at this time is used as the initial value for the storage circuit.
Remember in 10. The rise time is detected for each copy operation of several tens of sheets, the detected value and the initial value are input to the comparison circuit 18, and the filming is generated when the ratio becomes equal to or more than a preset value. Then, the control circuit is caused to send a signal for the filming removal operation. Here, setting values of several steps are provided for the ratio of the initial value and the detected value, the filming generation state is detected by several step ranks, and based on this rank, a preset program is used to detect the filming generation state. You may control the time of an anti-minging operation.

In this embodiment, a rubbing member 10 having a contact / separation mechanism for removing filming is provided on the downstream side of the cleaning blade 5. The installation place of the rubbing member 10 is not limited to this position. When the filming generation of the second image carrier 3 is detected from the rising time of the charging potential of the second image carrier 3, a signal of the filming removal operation is sent to the control circuit, and after a series of copying operations is completed or next time. Perform filming removal during warm-up after the main switch is turned on. The operation time for filming removal is determined based on the filming generation rank. According to the execution command from the control circuit, the drive motor of the filming removal brush is rotated, and at the same time, the contact / separation mechanism causes the rubbing member 10 to contact the second image carrier 3. At this time, if the contact pressure between the cleaning blade 5 and the second image carrier 3 is reduced, an operation of returning the contact pressure of the cleaning blade 5 to the reference value is performed after the filming removal operation is completed. Be seen.

From the viewpoint of cost, the rubbing member 10 of this embodiment has 120 denier / 48 filaments made of carbon-containing acrylic fiber, 93 loops / cm ² , a loop bristle length of 5 mm, and a brush outer diameter of 18 mm. The brush roller having the conductivity of the loop fiber is used. Using such a loop fiber, the brush rotation speed is 179 rpm and the brush nip width is 8 m.
2nd image carrier under the conditions of m and belt moving speed of 1.5mm / sec.
By rotating, the tip of the loop linearly abuts on the surface of the second image carrier, and evenly rubs the surface, and the friction coefficient between the second image carrier and the cleaning blade slides. What was 1.4 before decreased to 1.0 after the rubbing operation, and filming is removed. As another material of the loop fiber, a metal fiber such as stainless steel may be used.

In this embodiment, when the filming removal operation of the second image carrier 3 is performed, the second image carrier 3 is rotated while the cleaning blade 5 is in contact with the second image carrier 3. Then, the cleaning blade 5 is rubbed with no toner on the second image carrier 3, so there is a risk that the cleaning blade 5 may be caught when the blade is brought into contact with the cleaning blade 5 in the counter direction. .. Therefore, when the filming removal operation is performed, the cleaning blade 5 is separated from the second image carrier 3 and only the rubbing member 10 is contacted and rotated to rotate the second image carrier 3. However, the rubbing member 10 is replaced with the cleaning blade 5.
And the nip portion between the first image carrier 2 and the second image carrier 3, even if the cleaning blade 5 and the second image carrier 3 are in contact with each other during the image forming operation. A filming removal operation can be performed. Therefore, it is not necessary to set the filming removal mode only after completion of a series of copying operations, and it is possible to eliminate the copying operation unavailable time.

[0015]

[Outer 1] The force F ₂ becomes too large and the blade is caught. In this embodiment, the generation of filming is detected from the rise time of the charging potential of the second image carrier 3, and a signal is sent from the control circuit to the cleaning blade pressing force adjusting mechanism to set the contact pressure of the cleaning blade 5 to the reference value. Is also reduced [Fig. 9]. Normally, the contact pressure of the cleaning blade 5 is set to be relatively high in consideration of the margin so that the cleaning blade 5 can be cleaned even when a large amount of input toner such as untransferred toner is used. However, if the contact pressure is too large, the cleaning blade 5 may be rolled up and the drive roller 8 may idle even in the initial state without filming. Therefore, when using a blade with a hardness of 66 ° and a thickness of 2 mm as the reference value of the contact pressure, the contact pressure is set to 22 ° and the protrusion amount is 10 mm.
It is set to 20 gf / cm. If the contact pressure is reduced to 12 gf / cm under this condition, a cleaning failure will occur for the full-color untransferred image, but it will be sufficient for normal transfer residual toner. When the detection output of the potential sensor 15 reaches a predetermined value, the idling of the drive roller 8 is predicted and calculated from the initial value and the rising time characteristic, and the contact pressure is 12
Adjust the applied pressure to gf / cm to prevent idling,
The normal image formation is not affected. Further, in a low temperature and low humidity environment, the amount of charge on the second image carrier 3 increases and the adhesion force of the toner increases, or the Young's modulus of the second image carrier 3 and the cleaning blade 5 increases, so that the two adhere to each other. However, if the contact pressure is reduced, cleaning failure may occur with respect to the transfer residual toner. So temperature sensor 22
And the output of the humidity sensor 23, for example, when the temperature of the second image carrier 3 is 20 ° C. or less and the relative humidity is 20% RH or less,
The contact mechanism can be adjusted stepwise by the aforementioned adjustment mechanism so as to reduce the contact pressure to 15 gf / cm.

Although an example in which the present invention is applied to the second image carrier 3 has been described, the present invention is not limited to this, and the invention can be applied to another image forming apparatus having an image carrier that electrostatically carries and conveys a toner image. Can be used.

[0017]

The present invention is as described above, and the invention of claim 1 is a means for electrostatically transferring a toner image on a first image carrier to a second image carrier, In an image forming apparatus having a second image carrier that is rotatably driven by carrying the toner image that has been formed, after the toner image on the first image carrier is electrostatically transferred onto the second image carrier. A potential sensor for detecting the charging potential on the second image carrier, a storage circuit for storing the detection value of the potential sensor, and a comparison circuit for comparing a plurality of detection values with the output of the storage circuit being input. And a means for detecting a change in the resistance value and the electrostatic capacity of the second image carrier based on the output of the comparison circuit, and detecting a change in the resistance value and the electrostatic capacity of the second image carrier. Therefore, the filming generation of the second image carrier is detected, and the cleaning blade contact pressure is adjusted. Preventing entrainment of leaning the blade, there is an effect that the filming removal operation can be appropriately performed. According to a second aspect of the present invention, in the first aspect of the present invention, the toner image on the first image carrier is electrostatically transferred onto the second image carrier, upstream of the second image carrier in the transfer nip portion. A bias roller is arranged on the downstream side so as to form a transfer nip portion, a potential sensor for detecting the charging potential of the second image carrier is provided in the transfer nip portion, and the potential rise time is determined by the output of the potential sensor. Since the detection means is provided to detect the rise time of the potential at the transfer nip portion, filming generation of the second image carrier is detected and the cleaning blade contact pressure is adjusted to prevent the cleaning blade from being caught. However, there is an effect that the filming removal operation can be appropriately performed. According to a third aspect of the present invention, in the first or second aspect of the present invention, a rubbing member for polishing the surface of the second image carrier is provided so that it can be brought into contact with and separated from the second image carrier, and the rubbing member is output by the comparison circuit. It has an effect that it is possible to perform optimum filming removal in accordance with the amount of filming generated by providing a means for controlling the operation time of. According to a fourth aspect of the invention, in the first or second aspect of the invention, a cleaning member for removing the residual toner on the second image carrier is provided so that it can be brought into contact with and separated from the second image carrier, and the cleaning member is used as the second image carrier. A means for changing the pressure applied to the body by the output of the comparison circuit is provided to prevent the drive roller of the second image carrier from idling due to an increase in the frictional force between the cleaning member and the second image carrier. Therefore, there is an effect that the cleaning blade is not caught and the cleaning failure does not occur. According to a fifth aspect of the present invention, in the fourth aspect of the present invention, the temperature detection device detects the temperature of the second image carrier or the cleaning member, and the humidity detection device detects the humidity in the vicinity of the second image carrier. The temperature detection device and the humidity detection device are provided with means for adjusting the amount of change in the pressing force of the cleaning member brought into pressure contact with the second image carrier, and the optimum minimum pressing force corresponding to the environmental conditions. Can be set, and there is an effect that the cleaning blade is not caught and cleaning failure does not occur. According to a sixth aspect of the present invention, in any one of the first to fifth aspects, the second image is generated by releasing the cleaning member from the second image carrier during the operation of polishing the second image carrier by the rubbing member. Since the carrier is provided with a means for rotating the carrier, the cleaning member is not loaded, and the cleaning blade is not caught. According to a seventh aspect of the present invention, in any one of the first to fifth aspects, the rubbing member is carried on the first image carrier on the downstream side of the cleaning member with respect to the rotation direction of the second image carrier. The toner image is placed upstream of the portion where the toner image is transferred to the second image carrier, and when the cleaning member is in contact with the second image carrier, the output of the comparison circuit causes the resistance value of the second image carrier to change. Also, since the means for detecting the change in the electrostatic capacity and causing the rubbing member to contact the second image carrier to perform the rubbing operation based on the detection output, the filming is performed even during the image forming operation. It has the effect of being removable. Claim 8
In the invention described in any one of claims 1 to 7, since the cleaning member is an elastic blade that abuts in the counter direction with respect to the rotation direction of the second image carrier, the residual toner can be reliably removed with one blade. There is an effect that it can be cleaned and the cost of the apparatus can be reduced. The invention of claim 9 has the effect that in the invention of any one of claims 1 to 7, filming can be efficiently removed by a brush roller whose rubbing member is made of metal loop fibers. According to a tenth aspect of the present invention, in the invention according to any one of the first to seventh aspects, the rubbing member is a brush roller made of a loop fiber of a conductive resin, and filming can be efficiently performed at low cost. effective.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional view showing an embodiment of the present invention.

FIG. 2 is a diagram showing a state in which a bias voltage is applied to a nip portion between the first image carrier and the second image carrier and the first and second bias rollers of the same.

FIG. 3 is a characteristic diagram showing the voltage-current characteristics of the second image carrier and the rising time of the potential.

FIG. 4 is a characteristic diagram showing the relationship between the number of copies and the coefficient of friction in the above.

FIG. 5 is a schematic view of a cleaning blade pressing force adjusting mechanism of the above.

FIG. 6 is a configuration block diagram of the control device of the above.

[Figure 7]

[Outside 2]

[Figure 8]

[Outside 3]

[Figure 9]

[Outside 4]

[Explanation of symbols]

 1 image forming apparatus 2 first image carrier 3 second image carrier 4 holder 5 cleaning blade 6 pressure adjusting cam 7 pressure spring 8 drive roller 9 driven roller 10 rubbing member 11 backup roller 12 earth roller 13 first Bias roller 14 Second bias roller 15 Potential sensor 16 Memory circuit 17 Rise time detection circuit 18 Comparison circuit 19 Control circuit 20 Cleaning blade contact cam motor 21 Sliding member drive motor 22 Temperature sensor 23 Humidity sensor

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Takashi Misaji 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd.

Claims (10)

[Claims] 1. A means for electrostatically transferring a toner image on a first image carrier to a second image carrier, and a second image carrier that carries the transferred toner image and is driven to rotate. And an electric potential sensor for detecting a charging electric potential on the second image carrier after the toner image on the first image carrier is electrostatically transferred onto the second image carrier, A storage circuit that stores the detection value of the potential sensor and a comparison circuit that receives the output of the storage circuit and compares a plurality of detection values are provided. The output of the comparison circuit causes the resistance value of the second image carrier to be changed. An image forming apparatus comprising means for detecting a change in the capacitance and the capacitance. 2. A transfer nip portion is formed upstream and downstream of the second image carrier in the transfer nip portion for electrostatically transferring the toner image on the first image carrier onto the second image carrier. And a means for detecting the rise time of the potential based on the output of the potential sensor, the potential sensor for detecting the charging potential of the second image carrier is provided in the transfer nip portion. Image forming device. 3. A rubbing member for polishing the surface of the second image bearing member is provided so as to be able to come into contact with and separate from the second image bearing member, and means for controlling the operating time of the rubbing member is provided by the output of the comparison circuit. The image forming apparatus according to item 1 or 2. 4. A cleaning member for removing the residual toner on the second image carrier is provided so as to be able to come into contact with and separate from the second image carrier, and the pressing force for bringing the cleaning member into pressure contact with the second image carrier is determined by a comparison circuit. The device according to claim 1, further comprising means for changing the output.
Alternatively, the image forming apparatus of item 2. 5. A temperature detecting device for detecting the temperature of the second image bearing member or the cleaning member, and a humidity detecting device for detecting the humidity in the vicinity of the second image bearing member. The image forming apparatus according to claim 4, further comprising means for adjusting a change amount of a pressing force that presses the cleaning member against the second image carrier according to an output. 6. A means for rotating the second image bearing member by releasing the cleaning member from the second image bearing member during the operation of polishing the second image bearing member by the rubbing member. Image forming apparatus of any one of. 7. A rubbing member is located downstream of the cleaning member with respect to the rotation direction of the second image carrier, and a portion where the toner image carried on the first image carrier is transferred to the second image carrier. Is also arranged on the upstream side, and when the cleaning member is in contact with the second image carrier, the output of the comparison circuit detects the change in the resistance value and the electrostatic capacity of the second image carrier, and the detection output The image forming apparatus according to any one of claims 1 to 5, further comprising means for bringing a rubbing member into contact with the second image carrier to perform a rubbing operation. 8. The image forming apparatus according to claim 1, wherein the cleaning member is an elastic blade that abuts in a counter direction with respect to a rotation direction of the second image carrier. 9. The image forming apparatus according to claim 1, wherein the rubbing member is a brush roller made of metal loop fiber. 10. The image forming apparatus according to claim 1, wherein the rubbing member is a brush roller made of a loop fiber of a conductive resin.