JPH04177384A - Wet image forming device - Google Patents

Abstract

PURPOSE:To secure such a wet image former that keeps off any dripping from a cleaning device by setting up this cleaning device in and around the lowermost part of an image carrier surface. CONSTITUTION:A cleaning device 3 is set up in the lowermost part of a sensitizer drum 1, and it is provided with an elastic roller 31 and a cleaning blade 34 coming into counter-contact with a surface of the drum 1 at the more downstream side than this roller 31 in a direction of rotation of the drum 1. A lower part of this roller 31 is submerged in a developer being fed out of a developer tank in the device and collected in a casing of the device 3, and it is rotated and driven in the same direction as the drum 1, and a refreshing throttle rod 32 is made contact with the surface. Accordingly, at time of rotation stopping of an image carrier 1, a developer being fed to a surface of this image carrier 1 and stuck to this image carrier surface from the device 3 is recovered in the device 3 by its own weight. With this constitution, any dripping from the device 3 is preventable.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a wet image forming apparatus such as a copying machine, a facsimile machine, a printer, etc. using an electrophotographic method or an electrostatic recording method, which uses wet development. relates to an improvement of a cleaning device provided in a wet image forming apparatus.

[Conventional technology]

In a wet copying machine that uses a dish development method, the cleaning device is placed above the photoreceptor drum, which is the image carrier, as shown in FIG. It has become mainstream to use a roller development type developing device, with a transfer section formed below the photoreceptor drum and a cleaning device and a developing device placed on the sides of the photoreceptor drum, as shown in Figure 10. ing. In FIGS. 9 and 10, 1 is a photosensitive drum, 2 is a developing device, 3 is a cleaning device, 31 is an elastic roller, 32 is a squeeze rod for refreshing the elastic roller, and 33 is a liquid for supplying developer. Outlet, 34
4 is a cleaning blade, 4 is a static elimination lamp, 5 is a uniform charger, 6 is an erase lamp, and 7 is a transfer charger.

In the developing device 2, toner with a high solid content is used to improve image density and to downsize the replenishing toner container, and the amount of developer supplied onto the photoreceptor drum 1 is kept to a minimum. Due to the development of technology to set
The leakage (drip) of the developer from the developing device 2 can be suppressed.

On the other hand, in order to improve the cleaning performance of the cleaning device 3, it has been proposed to provide a plurality of cleaning blades (a first blade 35 and a second blade 36), as shown in FIG. 11, for example.

[Problem to be solved by the invention]

However, in the cleaning device 3 disposed above the photoreceptor drum l as described above or elsewhere, in order to remove the residual toner (untransferred toner) on the photoreceptor drum 1,
The cleaning blade 34 rotates in the direction of rotation of the photoreceptor drum 1.
Since the elastic roller 31 disposed upstream of the photoreceptor drum 1 supplies developer to the photoreceptor drum 1 to loosen untransferred toner, there is a risk of liquid dripping from this elastic roller or liquid dripping when the blade is released. There was. In particular, when using a toner with a high solid content due to image density requirements as described above, it is difficult to loosen the untransferred toner on the photoreceptor drum 1 and it is difficult to refresh the elastic roller 31 itself. , it was necessary to increase the amount of developer supplied to the elastic roller 31, and there was a high possibility of liquid dripping.

When this liquid drips onto the transfer paper on the conveyance path below the photoreceptor, there is a problem in that small particles of dirt are generated in the image, resulting in an abnormal image.

Also, the drippings adhere to the photosensitive drum 1 and the developing unit f1.
When moving to No. 2, there was a problem that color mixing occurred in color development.

Furthermore, if the liquid drips and dries and adheres to the photoreceptor drum 1 while the rotation of the photoreceptor drum 1 is stopped due to the completion of the copying operation, it may damage the cleaning blade 34 when the next rotation of the photoreceptor drum starts. In order to prevent this, it is necessary to provide a relatively long cleaning time to clean the surface of the photoreceptor when the photoreceptor starts rotating, which delays the first copy. There was a point.

In addition, in a cleaning device provided with a plurality of cleaning blades to improve cleaning performance as shown in FIG. The cleaning blade (first cleaning blade) located upstream in the direction of one rotation of the body drum
When the toner adhering to the surface of the photoreceptor drum 1 between the cleaning blade (second blade 36) located relatively downstream after passing through the blade 35) stops rotating the photoreceptor drum l. Since it dries and adheres to the surface of the photoreceptor drum 1, it places a large load on the cleaning blade (second blade 36) located relatively downstream when the next rotation of the photoreceptor drum 1 starts. may cause local wear or damage. When such partial wear or damage occurs to the cleaning blade (second blade 36) located relatively downstream, there is a problem in that black streaks occur on the image.

The present invention has been made in view of the problems of the prior art, and its first purpose is to provide a wet image forming apparatus that can prevent liquid dripping from the cleaning device. The second object is to provide a wet image forming apparatus that uses a cleaning device provided with a plurality of cleaning blades and can maintain good cleaning performance of the cleaning device.

[Means to solve the problem]

In order to achieve the first object, the invention according to claim 1 provides a wet-type image forming apparatus that develops a latent image on a rotating image carrier using a developer, in which a cleaning device is installed on the surface of the image carrier. It is characterized by being placed near the bottom of the.

In order to achieve the first and second objects, the invention according to claim 2 is the wet image forming apparatus according to claim 1, characterized in that the cleaning device is provided with a plurality of cleaning blades. The invention according to claim 3 is the wet-type image forming apparatus according to claim 2, wherein the plurality of cleaning blades include a first blade whose tip portion counter-contacts the surface of the image carrier; 4. The second blade is further downstream of the first blade in the direction of movement of the surface of the image carrier, the second blade having its leading end in trailing contact with the surface of the image carrier. According to the invention, the wet image forming apparatus according to claim 3 is characterized in that the wet image forming apparatus includes a cleaning liquid application means for applying cleaning liquid to the vicinity of the tip of the first blade.

[Effect]

In the invention according to claim 1, the cleaning device is disposed near the bottom of the surface of the image carrier, whereby when the rotation of the image carrier stops, the cleaning device supplies water to the surface of the image carrier. It functions to collect the adhering developer into the cleaning device by its own weight.

In the invention according to claim 2, the cleaning device is provided with a plurality of cleaning blades, thereby improving the cleaning performance, and the cleaning device is disposed near the bottom of the surface of the image carrier, thereby improving the cleaning performance of the image carrier. When rotation is stopped, the developing solution adhering to the surface of the image carrier between the plurality of cleaning blades is recovered into the cleaning device by its own weight.

〔Example〕

A first embodiment in which the present invention is applied to an electrophotographic wet copying machine will be described with reference to FIG.

First, an overview of the entire wet-type copying machine will be explained.

In FIG. 1, a photosensitive drum 1, which is an image carrier, is driven to rotate clockwise, is uniformly charged by a negative charger 5, and is charged with unnecessary parts by an erase lamp 6. In the system, reflected light from the original is imaged and projected to form an electrostatic latent image. This electrostatic latent image is converted into a toner image by a developer supplied from a developing device 2 provided above the photoreceptor drum 1, and this toner image is fed from a paper feeder (not shown) and is then transferred to the photoreceptor drum. The photoreceptor drum 1 is transferred to the transfer paper conveyed to the surface of the photosensitive drum 1 by the transfer charger 7, separated from the surface of the photoreceptor drum 1 by a separating device (not shown), and ejected outside the machine as copy paper through a fixing device and a paper ejecting device (not shown). Ru. On the other hand, the surface of the photoreceptor drum 1 after the transfer is charged with a −-like charge by collecting and removing untransferred toner with a cleaning device 3 disposed at the bottom of the photoreceptor drum 1, and then removing residual charges with a static elimination lamp 4. It is prepared for the next uniform charging by the device 5.

Next, the cleaning device 3 will be explained in detail.

The cleaning device 3 is disposed at the bottom of the photoreceptor drum 1 and includes an elastic roller 31 and a cleaning blade 34 that counter-contacts the surface of the photoreceptor drum 1 downstream of the elastic roller 31 in the rotational direction of the photoreceptor drum 1. ing. The lower part of the elastic roller 31 is supplied from a developer tank in the device and is immersed in the developer collected in the casing of the cleaning device 3, and is driven to rotate in the same direction as the photoreceptor drum 1, so that the surface of the elastic roller 31 is Aperture rod 3 for refreshing
2 are in contact.

In the above configuration, in the cleaning device 3, the elastic roller 31 is driven to rotate as the photoreceptor drum l rotates, and the developer in the cleaning casing is supplied to the surface of the photoreceptor drum 1 to remove untransferred toner on the photoreceptor drum 1. loosen,
The cleaning blade 3 removes this loosened untransferred toner.
4 and drop it into the developer in the cleaning casing, thereby cleaning the surface of the photoreceptor.

When the copying operation is completed, the rotation of the photosensitive drum 1 is stopped, and the rotation of the elastic roller 31 is also stopped. At this time, the developer adhering to the surface of the photoreceptor moves by its own weight along the surface of the photoreceptor drum 1 to the lowest part of the photoreceptor drum 1, falls into the cleaning casing, and is collected.

In this embodiment, a drum-shaped photoreceptor is used as the image carrier, but instead of this, a belt-shaped photoreceptor 1 can be used as shown in FIG.

In FIG. 2, the cleaning device 3 is disposed at the lowermost part of the photoreceptor, at the portion where it wraps around the belt pulley 11. As a result, similarly to the above embodiment, after the rotation of the photoreceptor belt 1 and the elastic roller 31 of the cleaning device 3 is stopped, the developer adhering to the surface of the photoreceptor belt 1 is transmitted along the surface of the photoreceptor belt 1 by its own weight. photoreceptor belt wheel 11
from where it wraps around the cleaning casing, where it falls into the cleaning casing and is collected.

Next, a second embodiment of the present invention will be described using FIG. 3.

In the above embodiment, the cleaning device 3 is provided with an elastic roller 31 and a cleaning blade 34, whereas in this embodiment, a plurality of blades are provided in the cleaning device 3 to improve cleaning performance.

In the third case, a digital writing optical system (not shown) is used to form a latent image on the photoreceptor drum 1, the latent image writing position is set to the side of the photoreceptor drum 1, and the transfer charger 4 is turned on. It is arranged above the photosensitive drum 1 and the transfer position is set above the photosensitive drum 1.

The cleaning device 3 includes a first blade 35 and a second blade 36 as cleaning blades that come into trailing contact with the surface of the photoreceptor drum 1. The tip of the second blade 36 on the downstream side in the rotation direction of the photoreceptor drum 1 contacts the surface of the photoreceptor drum 1 directly below the center of the photoreceptor drum 1, and the casing of the cleaning device 3 contacts the surface of the photoreceptor drum 1.
It is located below the lowest part of the photosensitive drum 1 including directly below the center. As a result, after the rotation of the photoreceptor drum 1 is stopped,
The developer adhering to the surface of the photoreceptor drum 1 moves along the surface of the photoreceptor drum 1 due to its own weight to the lowest part of the photoreceptor drum 1, and from there falls into the cleaning casing and is collected. Therefore, the first blade 35 and the second blade 35
The developer adhering to the surface of the photoreceptor between the blades 36 also travels along the surface of the photoreceptor to the tip of the second blade 36,
Further, it passes through the second blade 36 and falls into the cleaning casing.

In this embodiment, one of the two blades 35 and 36 is brought into trailing contact with the surface of the photoreceptor, but instead of this, the fourth blade
1! As shown in FIGS. ig to 6, a combination of a blade in counter contact and a blade in trailing contact, or a combination in which both blades make counter contact may be used. Further, as shown in FIG. 7, a cleaning brush roller 37 or the like may be provided in addition to the cleaning blade.

Next, a third embodiment of the present invention will be described using FIG. 8.

This embodiment uses a simple structure to prevent the cleaning blade that counter-contacts the photoreceptor surface from being caught when the photoreceptor surface starts rotating.

For example, in the cleaning device 3 shown in FIG.
When the photoreceptor belt 1 is stopped, the developer is not applied to the surface of the photoreceptor between the elastic roller 31 and the cleaning blade 34 even if the elastic roller 31 is rotated when the photoreceptor surface starts moving, and the contact angle of the cleaning blade Depending on the contact force, there is a possibility that the cleaning blade 34 may be caught when this portion passes the cleaning blade 34.

Cleaning blade 3 that comes into contact with such a counter
4. In order to prevent entrainment, conventionally, a pressure mechanism is provided that can change the cleaning blade 34 into a pressurized state in which its tip contacts the surface of the photoreceptor and a pressure release state in which the contact force is released. At the start of rotation, the pressure is kept in a released state until the surface of the photoconductor coated with the developer reaches the cleaning blade 34 by the elastic roller 31, and after the surface of the photoconductor coated with the developer reaches the cleaning blade 34, the pressure is kept in a pressurized state. . Therefore, there was a problem in that the pressure mechanism for the cleaning blade 34 became larger.

In order to solve this problem, it is conceivable to simply provide a mechanism for applying developer to the tip of the cleaning blade 34, but according to this, both end surfaces of the cleaning blade 34 (the front side and the back side in the paper) can be considered. There is a possibility that the developer flowing downstream from the end face of the photoreceptor surface in the direction of movement of the photoreceptor surface may mix into the developing device 2, causing color mixing in color development.

In FIG. 8, the cleaning device 3 is disposed below the surface of the photoreceptor belt 1 wound around the photoreceptor belt pulley 11, which is the lowest part of the photoreceptor belt 1. As shown in FIG. Inside the cleaning device 3, there is a first blade 35 that counter-contacts the surface of the photoreceptor belt 1 that is wrapped around the fourth quadrant of the photoreceptor belt wheel 11, and a photoreceptor belt that is wrapped around the third quadrant of the photoreceptor belt wheel 11. a cleaning liquid application nozzle 38 that applies a developer to the surface of the photoreceptor belt 1 on the upstream side in the moving direction of the photoreceptor belt 1 than the tip of the first blade 35; It is equipped with The length of the second blade 36 on the downstream side in the direction of movement of the surface of the photoreceptor belt 1 in the longitudinal direction (direction perpendicular to the paper) is set to be longer than that of the first blade 35 .

In the above configuration, the cleaning device 3 applies a developer to the surface of the photoreceptor belt 1 by driving the pump connected to the cleaning liquid application nozzle 38 at the same time that the rotation of the photoreceptor belt 1 is started. This prevents the dry surface of the photoreceptor from getting caught in the first blade 35 that is in counter contact while the photoreceptor belt 1 is stopped rotating. Also, the photoreceptor belt 1 scraped off by the first blade 35
The upper untransferred toner passes along the side surface of the first blade 35, falls into the cleaner casing under its own weight, and is collected. At this time, even if the developer flows from both end surfaces of the first blade 35 (the end surfaces on the front side and the back side in the paper) to the downstream side in the moving direction of the photoreceptor belt 1, the length in the longitudinal direction of the second blade 36 is Since it is longer than that of one blade 35, it can be completely scraped off with the second blade 36 and collected into the cleaning casing. Immediately after the photoreceptor belt 1 starts rotating, the surface of the photoreceptor belt 1 between the two blades, which is not coated with developer even by the cleaning liquid application nozzle 38, passes the second blade 36; Since this is a trailing abutment, the blade will not be caught in the blade.

In this embodiment, instead of the elastic roller 31, which is usually made of sponge or the like and tends to abrade the surface of the photoreceptor, the first blade 35 in contact with the counter is used. Changes in image density due to deterioration of body sensitivity can be suppressed, and the life of the photoreceptor can be extended.

Additionally, cleaning blades may be added which are in counter contact with the surface of the photoreceptor belt 1 wound around the third and fourth quadrants of the photoreceptor belt pulley 11, respectively. By increasing the number of cleaning blades in this way, the contact pressure of each cleaning blade can be set to a small value,
The life of the cleaning blade can be extended.

〔Effect of the invention〕

As described above, according to the invention according to claim 1, the cleaning device is disposed near the bottom of the surface of the image carrier, and when the rotation of the image carrier stops, the cleaning device supplies water to the surface of the image carrier. The developing solution adhering to the surface of the image carrier is collected into the cleaning device by its own weight, and this prevents the liquid from dripping from the cleaning device, which is an excellent method to prevent abnormal images from occurring. effective. Furthermore, since liquid dripping from the cleaning device is prevented, color mixing during color development can also be prevented. Furthermore, when the rotation of the image carrier stops, the developer supplied from the cleaning device to the surface of the image carrier and attached to the surface of the image carrier is collected into the cleaning device by its own weight, and is applied to the surface of the image carrier. Since it is possible to reduce the amount of developer that adheres, dries, and sticks, the cleaning time for cleaning the surface of the image carrier at the start of rotation of the image carrier can be omitted or shortened. It is possible to shorten the time it takes.

According to the invention according to claim 2, the cleaning device is disposed near the bottom of the surface of the image carrier, and when the rotation of the image carrier stops, the developer attached to the surface of the image carrier between the plurality of cleaning blades is removed. Since the liquid is collected into the cleaning device by its own weight, it is possible to prevent partial wear and damage to the cleaning blade located downstream in the direction of movement of the image carrier surface, thereby improving cleaning performance. The cleaning blade has an excellent effect of being able to maintain the image well and prevent the occurrence of black streaks on the image, and the plurality of cleaning blades include a first blade whose tip portion counter-contacts the surface of the image carrier; a second blade having its tip trailingly abutted on the image carrier surface on the downstream side of the first blade in the movement direction of the image carrier surface, and near the tip of the first blade; If a cleaning liquid applying means is provided for applying a cleaning liquid to the surface of the image bearing member, even when the rotation of the image bearing member starts, the surface of the image bearing member coated with the developer by the cleaning applying means passes through the first blade that is in counter contact with the blade. In addition, since the second blade comes into trailing contact, it is possible to prevent the second blade from becoming entangled.

[Brief explanation of drawings]

FIG. 1 is a front view of a schematic configuration of a wet-type copying machine according to a first embodiment of the present invention. FIG. 2 is a front view of the general configuration of a wet-type copying machine according to a modification of the first embodiment of the present invention. FIG. 3 is a front view of a schematic configuration of a wet type copying machine according to a second embodiment of the present invention. 4 to 7 are front views showing modified examples of the cleaning device 3 of the second embodiment. FIG. 8 is a front view of a cleaning device 3 for a wet copying machine according to a third embodiment of the present invention. 'FIG. 9 is a front view of the schematic structure of a wet-type copying machine according to the prior art. FIG. 10 is a front view of a schematic configuration of a wet type copying machine according to another conventional technique. FIG. 11 is a front view showing the arrangement of a cleaning blade of a cleaning device in a wet type copying machine according to still another conventional technique. 1... Photosensitive drum, photosensitive belt 2... Developing device, 3... Cleaning device 5
...Transfer charger, 31...Elastic roller 32...
・Aperture rod, 33...Liquid discharge port 34...Cleaning blade 35...First blade, 36...Second blade 37
... Cleaning brush roller 38 ... Cleaning liquid application nozzle

Claims (4)

[Claims] (1) A wet image forming apparatus that develops a latent image on a rotating image carrier using a developer, characterized in that a cleaning device is disposed near the bottom of the surface of the image carrier. Device. (2) The wet image forming apparatus according to claim 1, wherein the cleaning device is provided with a plurality of cleaning blades. (3) A first blade of the plurality of cleaning blades that counter-contacts a tip end thereof to the surface of the image carrier, and a first blade that contacts the surface of the image carrier on the downstream side of the first blade in the moving direction of the surface of the image carrier. 3. The wet type image forming apparatus according to claim 2, further comprising a second blade having a trailing end thereof in trailing contact with the second blade. (4) The wet image forming apparatus according to claim 3, further comprising a cleaning liquid applying means for applying cleaning liquid to the vicinity of the tip of the first blade.