JPH09230771A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device which restricts the behaviors of developer and toner, thereby preventing soil of a transfer belt and image irregularities. SOLUTION: A developing unit 7 facing a photoreceptor drum 1 has a developing roller 8 and reverse roller 9 arranged with a slight gap between the photoreceptor drum 1 and themselves. The rollers 8 and 9 are provided with scrapers 8a and 9a, respectively, which are in contact with them. A developing bias is applied to the developing roller 8 in order to prevent its surface from being soiled. The liquid developer is supplied to the developing roller 8, gathers onto the scraper 8, spreads over the developing roller 8 in its axial direction and becomes even. When the developing roller 8 rotates, this liquid developer reaches a nip between the photoreceptor drum 1 and the roller 8. The front edge of the area of liquid developer on the developing roller 8, at this time, is aligned almost on a straight line in the axial direction. When the liquid developer reaches the nip of the photoreceptor drum 1, the development bias is applied to the developing roller 8. Then reverse roller 9 forms a liquid- developer film of a specific thickness on the photoreceptor drum 1.

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 such as a copying machine or a laser printer for forming a visible image on a transfer sheet by a wet electrophotographic method.

[0002]

2. Description of the Related Art Conventionally, a wet-type image forming apparatus has a photosensitive drum, which is an image bearing member having an electrostatic latent image and a toner image formed on the surface thereof by an electrophotographic method. A charging charger that is a charging unit that charges, a writing unit that is a writing unit that optically writes an image on a photosensitive drum to form an electrostatic latent image, and a toner is attached to the electrostatic latent image by using a developing solution. A developing unit that is a developing unit that causes the cleaning and a cleaning unit that is a cleaning unit that removes excess toner on the photosensitive drum are provided. Further, the transfer unit, which conveys a transfer sheet as a transfer material, transfers the toner image on the photosensitive drum to the photosensitive drum. In this transfer unit, a transfer belt, which is a conveyer, extends along the direction in which a plurality of photoconductor drums are arranged, and a transfer roller, which is a transfer unit, faces the photoconductor drums with the transfer belt sandwiched therebetween.

[0003]

In the above-mentioned conventional image forming apparatus, since the liquid is used as the developer and the photosensitive drum and the transfer belt are in contact with each other, once the developer is supplied to the nip portion of both, The developer accumulates in a meniscus shape, which causes a problem that the transfer paper is soiled or the image is adversely affected. Also, considering the recovery operation at the time of jam where the transfer paper is not fed, for example, at the time of jam, the toner image on the photoconductor drum is directly transferred to the transfer belt, and the transfer belt is soiled, so that the transfer belt is not transferred. Therefore, it is preferable that the developer is not supplied to the nip when a jam occurs. Therefore,
SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus that regulates the behavior of a developing solution and toner to prevent dirt on a conveyance body that conveys a transfer material and disturbance of an image.

[0004]

In order to solve the above-mentioned problems, the invention of claim 1 is an image forming apparatus, and an image carrier on the surface of which an electrostatic latent image and a toner image are formed by an electrophotographic method, A charging unit that uniformly charges the image carrier, a writing unit that optically writes an image on the image carrier to form an electrostatic latent image, and a toner image on the image carrier as a transfer material. Transfer means for transferring, conveying means for holding the transfer material and conveying it so as to pass the transfer position by the transferring means, and attaching toner to the electrostatic latent image on the image carrier by using a developing solution. Developing means, cleaning means for removing excess toner on the image carrier, liquid removing means for removing excess developer on the image carrier, and prevention of excess toner from adhering to the background of the image carrier. A bias is applied to the developing means so that Developing bias applying means, an electric field forming means for forming an electric field between the surface of the image carrier on which the toner is attached by the developing means, and a residual potential removing means for erasing the residual potential on the image carrier. And is provided.

According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, a developing solution film is formed on the image carrier by the developing means when the image forming operation is started, and the developing solution film is stabilized. After that, the cleaning means is operated, and thereafter, a control means for controlling the electrostatic latent image forming operation by the charging means and the writing means and the transfer operation by the transfer means is started. To do.

According to a third aspect of the present invention, in the image forming apparatus according to the first aspect, the developing unit faces the image carrier with a predetermined gap, and the surface facing the facing portion is the image carrier. A developing roller rotatable so as to move in the same direction as the surface of, and a blade brought into contact with the developing roller so as to store the developing solution between the developing roller and supply the developing solution to the facing portion, A developing solution supply means for supplying a developing solution is provided between the developing roller and the blade.

According to a fourth aspect of the present invention, in the image forming apparatus according to the first aspect, when the image forming operation is started, a developing solution is stored between the developing roller and the blade, and the developing solution is used for the developing roller. When the developing roller is rotated in the axial direction, the tip of the developing solution on the developing roller reaches the portion facing the image carrier, and at the same time, the tip of the developing solution is transferred to the image bearing. After a predetermined time has passed after reaching the portion facing the body, a developing bias is applied to the developing roller by the developing bias applying means, and then the developing solution is uniformly supplied to the portion facing the image carrier. It is characterized by comprising control means for controlling the rotation of the image carrier after the start of the operation.

According to a fifth aspect of the present invention, in the image forming apparatus according to the first aspect, the liquid removing unit faces the image carrier with a predetermined gap, and the surface facing the facing portion is the image carrier. A liquid removing roller rotatable so as to move in a direction opposite to the surface of the body, a rotation driving means of the liquid removing roller, and the liquid removing roller so as to scrape off the developer on the liquid removing roller. And a blade.

According to a sixth aspect of the present invention, in the image forming apparatus according to the fifth aspect, when the image forming operation is started, the developing solution on the image carrier which has passed through the portion facing the developing means is the liquid removing roller. It is characterized by further comprising control means for controlling the rotation driving means so that the liquid removing roller starts to rotate before reaching a portion facing to.

According to a seventh aspect of the present invention, in the image forming apparatus according to the first aspect, the electric field forming means faces the image carrier with a predetermined gap, and the surface facing the facing portion is the image carrier. An electric field forming roller that is rotatable so as to move in the same direction as or a direction opposite to the surface, a rotation driving means of the electric field forming roller, and the electric field forming roller that contacts the electric field forming roller so as to scrape off the developer. And a blade.

According to an eighth aspect of the present invention, in the image forming apparatus according to the first aspect, when the image forming operation is started, the developing solution on the image carrier which has passed through a portion facing the developing means is the electric field forming roller. It is characterized by further comprising control means for controlling the rotation driving means so that the electric field forming roller starts to rotate before reaching a portion facing to.

According to a ninth aspect of the present invention, in the image forming apparatus according to the first aspect, when the image forming operation is started, the developing solution on the image carrier passing through a portion facing the developing means is caused by the cleaning means. It is characterized by comprising control means for controlling to start the cleaning operation by the cleaning means after passing through the cleaning position.

According to a tenth aspect of the present invention, in the image forming apparatus according to the first aspect, the cleaning means includes a cleaning blade and a cleaning roller that can be brought into and out of contact with the image carrier, and the cleaning blade and the cleaning roller. And a cleaning liquid supply unit for supplying a cleaning liquid to the cleaning roller, and when the image forming operation is started, the cleaning blade and the cleaning roller are brought into contact with the image carrier by the separating and contacting unit. After that, a control means for controlling the liquid supply means to supply the cleaning liquid to the cleaning roller is provided.

According to an eleventh aspect of the invention, in the image forming apparatus according to the first aspect, the electrostatic latent image forming operation by the charging means and the writing means and the transfer operation by the transfer means are stopped when the image forming operation is completed. After that, the cleaning operation by the cleaning unit is stopped, the rotation of the image carrier is stopped, and then the developing operation by the developing unit, the excess liquid removing operation by the liquid removing unit, and the rotation of the electric field forming unit are performed. It is characterized in that it is provided with a control means for controlling to terminate.

According to a twelfth aspect of the invention, there is provided the image forming apparatus according to the first aspect, wherein an image is formed by a positive / positive developing system, wherein after the charging operation by the charging means is completed at the end of the image forming operation, The writing means erases the potential of the charged portion until the charged portion on the image carrier has passed the writing position by the writing means, and then stops the potential erasing operation by the writing means. It is characterized in that it is provided with a control means for controlling.

According to a thirteenth aspect of the present invention, in the image forming apparatus according to the first aspect, the cleaning means includes a cleaning blade and a cleaning roller that can be brought into contact with and separated from the image carrier, and the cleaning blade and the cleaning roller. And a rotating / driving means for the cleaning roller, and a cleaning liquid supply means for supplying a cleaning liquid to the cleaning roller. When the image forming operation is completed, the cleaning liquid is supplied by the cleaning liquid supply means. After stopping, the rotation of the cleaning roller is stopped, and thereafter, there is provided control means for controlling so that the cleaning blade and the cleaning roller are separated from the image carrier by the separating / contacting means to stop the cleaning operation. It is characterized by.

According to a fourteenth aspect of the present invention, in the image forming apparatus according to the third aspect, the rotation of the image carrier is stopped after the supply of the developing solution by the developing solution supply means is stopped at the end of the image forming operation. The present invention is characterized by comprising control means for stopping and then stopping the rotation of the developing roller to stop the developing operation.

According to a fifteenth aspect of the invention, in the image forming apparatus according to the fifth aspect, the rotation of the liquid removing roller is stopped by the rotation driving means after the rotation of the image carrier is stopped at the end of the image forming operation. It is characterized by comprising a control means for controlling so as to stop.

According to a sixteenth aspect of the present invention, in the image forming apparatus according to the seventh aspect, the rotation of the electric field forming roller is stopped by the rotation driving means after the rotation of the image carrier is stopped at the end of the image forming operation. It is characterized by controlling so as to stop. (Hereinafter, margin)

According to a seventeenth aspect of the present invention, in the image forming apparatus according to the first aspect, the separating / contacting means for separating and contacting the conveying body with respect to the image carrier, and the power supply of the apparatus main body when the power is off or in the standby state A control unit that separates the carrier from the image carrier, and controls the contacting / disconnecting unit to bring the carrier into contact with the image carrier at the start of the image forming operation before the writing operation by the writing unit is started. It is characterized by including.

According to a eighteenth aspect of the present invention, in the image forming apparatus according to the first aspect, a separating / contacting unit for separating and contacting the carrier with respect to the image carrier, and a member on the carrier when the image forming operation is completed. (3) Immediately after the final transfer material has passed the transfer position of the transfer means, the control means controls the separating / contacting means so as to start the separation of the transport body.

According to a nineteenth aspect of the present invention, in the image forming apparatus according to the first aspect, there is provided a transfer material separating means for separating the transfer material after the transfer from the carrier body, and a discharging means for discharging the charge of the carrier body. The transfer unit is configured to perform the three operations of the transfer operation, the transfer material separating operation, and the charge removing operation on a portion of the transport body that is in contact with the first transfer material at the start of the image forming operation. And a control means for controlling the transfer material separating means and the charge removing means.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to the drawings. In FIG. 1, the image forming apparatus is
It has a photosensitive drum 1 which is an image carrier on the surface of which an electrostatic latent image and a toner image are formed by an electrophotographic method. This photosensitive drum 1 is, as shown in FIG. 2, an MPU 1 which is a control means.
1 is driven by controlling a drive motor 21 which is a rotation drive means via a motor driver 20.

A transfer unit 2 is provided on the side of the photosensitive drum 1.
Is provided. The transfer unit 2 includes a transfer belt 2a, which is a transporting member extending in the vertical direction, a transfer roller 2b, which is a transfer unit that contacts the photosensitive drum 1 with the transfer belt 2a sandwiched therebetween, and an end portion of the transfer belt 2a, which is not shown. And a drive roller. A drive motor 23 is connected to a drive roller (not shown), and the transfer belt 2 a is cyclically driven by the MPU 11 controlling the drive motor 23 via the motor driver 22. The transfer belt 2a can be brought into and out of contact with the photosensitive drum 1 by a cam driven by a motor (not shown). The transfer belt 2a is a transfer material separating unit that is charged by the transfer roller 2b so as to electrostatically adsorb the transfer paper, which is a transfer material, and uses a drive roller (not shown) as a counter electrode to separate the transfer paper. Separated by separation charge. Further, in response to these charges, the transfer belt 2a is corona-charged so that the charge is removed by a driving roller (not shown) or a counter electrode member (not shown) that is a discharging unit. Transfer roller 2b
Is a high-voltage power supply 2 that electrostatically attaches toner to the transfer paper.
Biased by 4.

A cleaning unit 3, which is a cleaning means, is provided above the photosensitive drum 1.
The cleaning unit 3 removes the form roller 3a, which is a cleaning roller that contacts the photoconductor drum 1 to collect the developer, the squeeze roller 3b that contacts the form roller 3a, and the residual toner on the surface of the photoconductor drum 1. A cleaning blade 3c for scraping off is provided. The foam roller 3 a is rotationally driven by the MPU 11 controlling the drive motor 27 via the motor driver 26. The cleaning liquid is supplied to the foam roller 3 a by the MPU 11 controlling the cleaning liquid supply motor 28, which is a liquid supply means, via the motor driver 27. A developing solution may be used as the cleaning solution. The squeeze roller 3b is for removing the toner collected by the foam roller 3a.
A cleaning contact / separation motor 31, which is a contact / separation unit, is connected to the foam roller 3a and the cleaning blade 3c via a cleaning contact / separation clutch 33, and is displaceable with respect to the photosensitive drum 1 in a freely contactable / separable manner. The cleaning contact / separation motor 31 and the cleaning contact / separation clutch 33
Is controlled by the MPU 11 via the drivers 30 and 32.

On the downstream side (arrow) of the photoconductor drum 1 of the cleaning unit 3, a charge eliminating lamp 4 including a cold cathode tube as a residual potential removing means faces. The charge removal lamp 4 is turned on when the MPU 11 controls the driver 33. Also, instead of this static elimination lamp, L
A light source such as an ED may be used.

A corotron type or scorotron type charging charger 5 which is a charging means for uniformly charging the surface of the photosensitive drum 1 is provided on the downstream side of the discharging lamp 4. The charging charger 5 is charged by the MPU 11 controlling the high-voltage power supply 35.

On the downstream side of the charging charger 5, there is a writing unit 6 which is a writing means for optically writing an image on the photosensitive drum 1 to form an electrostatic latent image. In the writing unit 6, the MPU 11 controls writing by the LD driver 35 to perform laser scanning. A laser light source (LD) is used as a light source of the writing unit 6. Further, as the writing means, an LED or one using liquid crystal may be used.

A developing unit 7 as a developing means is provided from the side portion to the lower portion of the photosensitive drum 1. The developing unit 7 includes a developing roller 8 and
A reverse roller 9 that is a liquid removing roller that removes excess developer and a set roller 10 that is an electric field forming roller are sequentially provided. Each of the rollers 8, 9 and 10 is provided with blade-shaped scrapers 8a, 9a and 10a so as to come into contact with the rollers. The developing roller 8 faces the photoconductor drum 1 so as to have a gap of about 100 to 200 μm, and rotates so that the surface moves in the same direction as the photoconductor drum 1 at the facing portion.

The developing roller 8 is rotationally driven by the MPU 11 controlling a drive motor 37, which is a rotational driving means, via a driver 36. A developing bias is applied to the developing roller 8 in order to prevent the background portion of the surface of the photosensitive drum 1 from being contaminated. The developing bias of the developing roller 8 is applied by the MPU 11 controlling the high voltage power source 39 which is a developing bias applying means.

The reverse roller 9 is the photosensitive drum 1
With respect to the photoconductor drum 1 so as to have a gap of about 50 to 100 μm, and rotate so that the surface moves in the opposite direction to the photoconductor drum 1 at the facing portion. The reverse roller 9 is rotationally driven by the MPU 11 controlling a drive motor 41, which is a rotational drive means, via a driver 40. The set roller 10 is 5 with respect to the photosensitive drum 1.
Facing each other with a gap of 0 to 150 μm,
It rotates so that the surface moves in the same direction as the photosensitive drum 1 at the facing portion.

In the set roller 10, the MPU 11 via the driver 42 drives the drive motor 43 as a rotation drive means.
It is driven to rotate by controlling. Set roller 1
To 0, a set bias for forming a discharge electric field between the toner and the surface of the photosensitive drum 1 is applied in order to strengthen the connection between the toners after development and stabilize the state before transfer. It has become. This set roller 1
The set bias of 0 is applied by the MPU 11 controlling the high-voltage power supply 44.

The scrapers 8a, 9a and 10a scrape off the toner adhering to the surface of the roller. The developing solution is supplied to the developing unit 7 by the MPU 11 controlling the developing solution supply motor 45 via the motor driver 44.

The MPU 11 also controls a paper feed control unit 46 for controlling paper feed and a fixing control unit 47 for fixing toner.

Next, the procedure for starting the image forming operation in the image forming apparatus having the above configuration will be described with reference to FIG. In this image forming apparatus, first, a liquid film of a developing solution is formed on the photosensitive drum 1 to stabilize it. That is, the developing solution supply pump is operated (t1) to supply the developing solution to the developing unit 7. The developer is collected on the scraper 8a, and after a few seconds, spreads on the developing roller 8 in the axial direction to be uniformized. When the developing roller 8 rotates (t2), the developing solution accumulated between the developing roller 8 and the scraper 8a reaches the nip portion with the photosensitive drum 1. At this time, the leading ends of the developing solution on the developing roller 8 are substantially aligned in the axial direction.

When the developing solution reaches the nip portion of the photosensitive drum 1, a developing bias is applied to the developing roller 8. The timing (t3) of application of the developing bias is delayed from the time when the developing roller 8 is rotated by the time found by experiment or calculation because it cannot actually detect that the developing solution reaches the photosensitive drum 1. . The developing bias has a polarity opposite to that of the toner to prevent the toner from adhering to the background surface of the photosensitive drum 1. However, if the developing bias is continuously applied to the developing roller 8 while the photoconductor drum 1 is stopped, a potential trace appears on the photoconductor drum 1 as a white streak in the image. It is necessary to rotate the photosensitive drum 1 within the time.

Next, the reverse roller 9 and the set roller 10 are rotated together with the photosensitive drum 1 (t3), and at the same time, the charge eliminating lamp 4 is turned on to smooth the surface potential of the photosensitive drum 1 before charging. The squeeze effect of the reverse roller 9 on the photosensitive drum 1 largely changes depending on the number of revolutions of the reverse roller 9 and the gap with the photosensitive drum 1, and also relates to the thickness of the liquid film on the photosensitive drum 1. For example, if the film thickness is thinner than the gap, the developer will slip through the reverse roller 9 without touching it. For this reason,
Before reaching the reverse roller 9, the film thickness on the photosensitive drum 1 is maintained thicker than the gap with the reverse roller 9,
Must be stable. Further, the rotation of the reverse roller 9 must be stable before the tip of the liquid film on the photosensitive drum 1 reaches the reverse roller 9.

When the surface of the photoconductor drum 1 is sufficiently wet with the developing solution, the foam roller 3a and the cleaning blade 3c of the cleaning unit 3 are brought into contact with the photoconductor drum 1 by the cleaning contact / separation motor 31 and the cleaning contact / separation clutch 33. Allow (t4). When the contact between the cleaning blade 3c and the photosensitive drum 1 is detected by the photo interrupter (t5), the cleaning contact / separation motor 30 is stopped to maintain the contact state. Instead of providing the photo interrupter, the cleaning contact / separation motor 30 may be automatically stopped after a predetermined time. After the contact, the cleaning liquid supply motor 29 supplies the cleaning liquid to the foam roller 3a and rotates the foam roller 3a.

After the cleaning unit 3 is actuated and the developing solution and the like on the surface of the photosensitive drum 1 on the downstream side are removed and the cleaning unit 3 becomes clear, the image forming process is started. That is, the charging of the photosensitive drum 1 by the charging charger 5,
The transfer belt 2a is driven, the electrostatic latent image is formed by the writing unit 6, the developing unit 7 visualizes the image, and the transfer belt 2a is circulated (t6).

In response to this, in the transfer unit 2, first, the charge of the transfer belt 2a is removed by the charge removal charger 26 (t7). At the same time, the transfer belt 2a is electrostatically charged on the paper feed side (not shown) to electrostatically adsorb the transfer paper, and the transfer belt 2a is separately charged on the paper discharge side to separate the transfer paper. Further, the transfer roller 2b is biased to electrostatically attach the toner to the transfer paper, and at the same time, the portion of the transfer belt 2a where the transfer paper is separated is wiped off the adhered matter on the surface by a web or the like (not shown). At this time, the bias of the set roller 10 and the contacting operation of the transfer belt 2a to the photosensitive drum 1 by the contact motor are performed. This is because the developing process of the photoconductor drum 1 is performed, so that the photoconductor drum 1 is not affected even when the transfer roller 2b is operated, and the image writing is performed in a state where all the electrostatic loads are ON. This is because the photosensitive drum 1 is rotated for as long a time as possible before performing the step (1) to bring it into a stable state. The writing operation by the writing unit 6 is started after the belt contact / separation sensor detects a completely contacted state so that the image is not disturbed by the impact of the transfer belt 2a contacting the photosensitive drum 1.

After the transfer preparation as described above is completed, the registration roller feeds the transfer paper one by one. When the transfer belt 2a does not come into contact with or separate from the photosensitive drum 1, the contact operation of the transfer belt 2a to the photosensitive drum 1 is omitted.

Next, the procedure for ending the image forming operation in the image forming apparatus having the above configuration will be described with reference to FIG. After passing the final transfer paper, the charger 5 and the set roller 1
0 and the bias of the transfer roller 2b are turned off (t1
1). This reduces the burden on the photosensitive drum 1 and the wasteful consumption of toner. At this time, the LD of the writing unit is turned off after there is no charged portion on the photosensitive drum 1. At the same time, the transfer belt 2a is separated from the photosensitive drum 1 so that the transfer belt 2a does not become dirty due to contact with the photosensitive drum 1 (t12). At this time, in consideration of the transportability of the transfer paper, the stability of the surface potential of the transfer belt 2a and the like, and the stability of the image, the transfer belt 2a is exposed after the last transfer paper is completely separated from the transfer belt 2a. Separate from body drum 1.

Then, the supply of the cleaning liquid is stopped (t
13), the charge removal charge of the transfer belt 2a and the separation charge for separating the transfer paper are turned off (t14), the drive motor 23 of the transfer belt 2a is stopped, and then the foam roller 3a that has become less wet is stopped. (T15). After this, the foam roller 3a and the cleaning blade 3
c is separated from the photosensitive drum 1 (t16). When the cleaning blade 3c is separated from the photosensitive drum 1, the developing solution accumulated on the cleaning blade 3c is removed from the photosensitive drum 1.
Is carried to the developing unit 7 and collected.
If the trace of the cleaning blade 3c is not removed by one rotation of the photoconductor drum 1, the trace is removed by rotating it a plurality of times.

After this, the liquid supply pump is turned off (t17).
The accumulation of the developing solution is eliminated between the developing roller 8 and the scraper 8a. The photosensitive drum 1 is stopped before the developer is no longer supplied from the developing roller 8 to the photosensitive drum 1 and the reverse roller 9 does not function (t1).
8). The purpose of this is to stop the developing solution on the photosensitive drum 1 while keeping the film thickness of the developing solution constant, and at the time of stopping, the developing solution intervenes only in the nip portion of the developing roller 8. The developing roller 8 continues to rotate after this, so that the developer in the nip portion decreases. The photosensitive drum 1 is stopped, the static elimination lamp 4 is turned off, the developing bias is turned off within a short time (t19), and then the developing roller 8, the reverse roller 9 and the set roller 10 are stopped (t20).

[0045]

As described above, according to the first aspect of the present invention, the developing bias applying means prevents the toner from adhering to the background portion of the surface of the image carrier, and the excessive developing solution removing means causes the excessive developing. Since the liquid is removed, the developer does not accumulate in a meniscus shape, so that the transfer material can be prevented from being contaminated and the image can be prevented from being adversely affected. There is an effect that the toner image is not transferred to the transport body, the transport body can be prevented from being soiled, and in the case of a color image forming apparatus, color mixture due to the soiling of the transport body can be avoided.

According to the second aspect of the present invention, since the film of the developer on the image bearing member is in a better condition, the burden on the cleaning means is reduced and the durability of the cleaning means can be extended. The amount of liquid pool between the image carrier and the carrier can be reduced.

According to the third aspect of the present invention, it is possible to prevent the background portion of the image bearing member from being soiled, improve the image quality, and reduce the load on the cleaning means.

According to the fourth aspect of the present invention, it is possible to prevent the image from being disturbed due to the application of the developing bias in the state where the rotation of the image bearing member is stopped, and to prevent the background portion from being delayed due to the delay of the application of the developing bias. It can prevent dirt.

According to the fifth aspect of the invention, the developer on the image carrier can be scraped off well.

According to the sixth aspect of the invention, since the developing solution reaches after the rotation of the solution removing roller is stabilized, it is ensured that the developing solution film on the image carrier spreads. Can be in good condition.

According to the invention of claim 7, a bias voltage can be favorably applied to the electric field forming roller.

According to the eighth aspect of the invention, since the rotation of the electric field forming roller is ensured before reaching the developing solution, the surface of the electric field forming roller can be kept in a clean state, and the bias voltage to the electric field forming roller can be made. Can be applied more favorably.

According to the ninth aspect of the invention, since the cleaning means operates after the developing solution is applied on the image carrier, the mechanical load can be reduced and the life of the cleaning means can be extended. it can.

According to the invention of claim 10, liquid leakage from the cleaning roller can be prevented. Further, since the cleaning blade and the cleaning roller can be brought into and out of contact with each other, the deformation of the cleaning blade and the cleaning roller can be reduced and the life can be extended.

According to the eleventh aspect of the present invention, it is possible to reduce the electrostatic load applied to the image carrier and prevent the toner from sticking.

According to the twelfth aspect of the present invention, it is possible to reduce the contamination of the background portion of the image bearing member and reduce the consumption of toner.

According to the thirteenth aspect of the present invention, it is possible to prevent the liquid from leaking from the cleaning means and to stop the apparatus after ensuring the image carrier in a clean state.

According to the fourteenth aspect of the invention, since the image carrier is stopped after removing the developer, it is possible to prevent the toner from sticking between the image carrier and the developing means.

According to the fifteenth aspect of the invention, since the liquid removing roller is stopped after removing the developing solution, it is possible to prevent the toner from sticking between the image carrier and the liquid removing roller.

According to the sixteenth aspect of the invention, since the electric field forming roller is stopped after the developing solution is removed, it is possible to prevent the toner from sticking between the image carrier and the electric field forming roller.

According to the seventeenth aspect of the present invention, it is possible to minimize the stain on the conveyance body during image formation. (Hereinafter, margin)

According to the eighteenth aspect of the present invention, it is possible to minimize the contamination of the carrier during image formation and reduce the load on the carrier.

According to the nineteenth aspect of the present invention, the surface condition of the carrier is made uniform and the image is not adversely affected.

[Brief description of drawings]

FIG. 1 is a schematic front view of an image forming apparatus according to the present invention.

FIG. 2 is a block diagram of a control unit of the image forming apparatus.

FIG. 3 is a time chart at the start of image formation of the image forming apparatus.

FIG. 4 is a time chart at the end of image formation by the image forming apparatus.

[Explanation of symbols]

 1 Photoconductor Drum 2 Transfer Unit 2a Transfer Belt 2b Transfer Roller 3 Cleaning Unit 3a Foam Roller 3c Cleaning Blade 4 Electrification Lamp 5 Charging Charger 6 Writing Unit 7 Developing Unit 8 Developing Roller 9 Reverse Roller 10 Set Roller 8a, 9a, 10a Scraper

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location G03G 21/00 370 G03G 21/00 340

Claims (19)

[Claims] 1. An image carrier on which an electrostatic latent image and a toner image are formed on the surface by electrophotography, a charging unit for uniformly charging the image carrier, and an image optically formed on the image carrier. Writing means for writing electrostatically to form an electrostatic latent image, transfer means for transferring the toner image on the image carrier to a transfer material, and holding the transfer material so that the transfer material passes through a transfer position by the transfer means. A conveying means for conveying the toner to the electrostatic latent image on the image bearing member, and a developing means for adhering the toner to the electrostatic latent image on the image bearing member using a developing solution.
A cleaning unit that removes excess toner on the image carrier, a liquid removing unit that removes excess developer on the image carrier, and a liquid removing unit that prevents the excess toner from adhering to the background of the image carrier. A developing bias applying unit that applies a bias to the developing unit, an electric field forming unit that forms an electric field between the surface of the image carrier on which the toner is attached by the developing unit, and a residual potential on the image carrier are An image forming apparatus comprising: a residual potential removing unit for erasing. 2. When an image forming operation is started, a developing solution film is formed on the image carrier by the developing means, the developing solution film is stabilized, and then the cleaning means is operated, and then the charging means. 2. The image forming apparatus according to claim 1, further comprising control means for controlling the electrostatic latent image forming operation by the writing means and the transfer operation by the transfer means to start. 3. A developing roller, wherein the developing means faces the image carrier at a predetermined gap and is rotatable so that the surface facing the facing part moves in the same direction as the surface of the image carrier. A blade that is in contact with the developing roller so that the developing solution is stored between the developing roller and the developing roller and the developing solution is supplied between the developing roller and the blade. The image forming apparatus according to claim 1, further comprising a liquid supply unit. 4. When the image forming operation is started, a developing solution is accumulated between the developing roller and the blade, and when the developing solution is spread in the axial direction of the developing roller, the developing roller is rotated and the developing roller is rotated. At the same time that the front end of the developer reaches the facing portion with the image carrier, or after a predetermined time has elapsed from the front end of the developer reaching the facing portion with the image carrier, A developing bias is applied to the developing roller by the developing bias applying means, and then, the rotation of the image carrier is controlled after the developing solution is uniformly supplied to a portion facing the image carrier. The image forming apparatus according to claim 3, further comprising a control unit. 5. The liquid removing means is opposed to the image carrier at a predetermined gap and is rotatable so that a surface facing the facing part moves in a direction opposite to the surface of the image carrier. The image according to claim 1, further comprising: a roller, a rotation driving unit of the liquid removing roller, and a blade that is in contact with the liquid removing roller so as to scrape off the developing solution on the liquid removing roller. Forming equipment. 6. When the image forming operation is started, the liquid removing roller is rotated before the developer on the image carrier that has passed through the portion facing the developing means reaches the portion facing the liquid removing roller. The image forming apparatus according to claim 5, further comprising a control unit that controls the rotation driving unit to start the rotation. 7. An electric field which the electric field forming means faces the image carrier at a predetermined gap and is rotatable so that the surface facing the facing part moves in the same direction or in the opposite direction to the surface of the image carrier. The forming roller, a rotation driving means for the electric field forming roller, and a blade that is in contact with the electric field forming roller so as to scrape off the developing solution on the electric field forming roller. Image forming apparatus. 8. The electric field forming roller is rotated before the developing solution on the image carrier, which has passed through the facing portion with the developing means, reaches the facing portion with the electric field forming roller at the start of an image forming operation. The image forming apparatus according to claim 7, further comprising a control unit that controls the rotation driving unit to start the rotation. 9. The cleaning operation by the cleaning means is started after the developing solution on the image carrier which has passed through a portion facing the developing means has passed a cleaning position by the cleaning means at the start of the image forming operation. 2. A control means for controlling as described above is provided.
An image forming apparatus according to claim 1. 10. A cleaning device, wherein said cleaning means supplies a cleaning liquid to said cleaning roller and a cleaning roller, a cleaning blade and a cleaning roller capable of separating and contacting said image bearing member, and a separating and contacting means of said cleaning blade and said cleaning roller. A liquid supply unit, and at the start of the image forming operation, the cleaning blade and the cleaning roller are brought into contact with the image carrier by the separating / contacting unit, and then the cleaning liquid is supplied to the cleaning roller by the liquid supply unit. The image forming apparatus according to claim 1, further comprising a control unit that controls to perform the following. 11. At the end of the image forming operation, after stopping the electrostatic latent image forming operation by the charging means and the writing means and the transfer operation by the transfer means, the cleaning operation by the cleaning means is stopped and the image is formed. It is characterized by further comprising control means for stopping the rotation of the carrier and thereafter controlling the developing operation by the developing means, the excess liquid removing operation by the liquid removing means, and the rotation of the electric field forming means. The image forming apparatus according to claim 1. 12. The image forming apparatus according to claim 1, wherein the image is formed by a positive / positive developing method, and after the charging operation by the charging unit is completed at the end of the image forming operation, the image is formed on the image carrier. Control means for erasing the potential of the charged portion by the writing means until the charged portion of the writing means has finished passing the writing position by the writing means, and then stopping the potential erasing operation by the writing means. An image forming apparatus comprising: 13. The cleaning means includes a cleaning blade and a cleaning roller that can be brought into and out of contact with the image carrier, a detaching and contacting means of the cleaning blade and the cleaning roller, a rotation driving means of the cleaning roller, and A cleaning liquid supply means for supplying a cleaning liquid to the cleaning roller, and at the end of the image forming operation, after the supply of the cleaning liquid by the cleaning liquid supply means is stopped, the rotation of the cleaning roller is stopped, and thereafter, The image forming apparatus according to claim 1, further comprising a control unit that controls the cleaning blade and the cleaning roller to be separated from the image carrier by a contacting / separating unit to stop the cleaning operation. 14. At the end of the image forming operation, the supply of the developing solution by the developing solution supply means is stopped, the rotation of the image carrier is stopped, and then the rotation of the developing roller is stopped to perform the developing operation. The image forming apparatus according to claim 3, further comprising control means for controlling so as to stop. 15. At the end of the image forming operation, after the rotation of the image carrier is stopped, a control means for controlling the rotation of the liquid removing roller by the rotation driving means is provided. The image forming apparatus according to claim 5. 16. The control according to claim 7, wherein after the image forming operation is finished, the rotation of the image carrier is stopped and then the rotation of the electric field forming roller by the rotation driving means is stopped. The image forming apparatus described. 17. A separation / contact means for separating and contacting the carrier with respect to the image carrier, and a carrier for separating the carrier from the image carrier when the apparatus main body is powered off or in a standby state, and when the image forming operation is started. The image forming apparatus according to claim 1, further comprising: a control unit that controls the contacting / separating unit so as to bring the carrier into contact with the image carrier before the writing operation by the writing unit is started. apparatus. 18. A separation / contact means for separating / contacting the carrying body from / to the image carrier, and after the final transfer material on the carrying body has passed a transfer position by the transfer means at the end of the image forming operation, The image forming apparatus according to claim 1, further comprising a control unit that controls the separating / contacting unit so as to start separating the transport body. 19. A transfer material separating means for separating the transfer material after transfer from the carrying body, a charge removing means for removing charge of the carrying body, and a first transfer material of the carrying body at the start of an image forming operation. Control means for controlling the transfer means, the transfer material separating means, and the charge removing means so that the transfer operation, the transfer material separating operation, and the charge removing operation are performed on the contacting portion. The image forming apparatus according to claim 1, further comprising: