JPH07302028A - Wet type developing device - Google Patents

Abstract

PURPOSE:To prevent the occurrence of a failure in squeezing with a squeezing roller and simultaneously to improve the durability of a blade by preventing the missing of the edge part of the blade removing a developer on the squeezing roller. CONSTITUTION:This wet type developing device is provided with a scraper 24 abutted on the outer periphery of the squeezing roller 14 abutted on the outer periphery of a photoreceptor l and rotated in this state to remove, the fixed toner fixed on the outer periphery of the roller 14 and the blade 23 abutted thereon to remove the developer stuck to the roller 14. Then, the scrapper 24 and the blade 23 are arranged in order from the upstream side to the downstream side along the rotational direction of the roller 14 based on the abutting place on the photoreceptor 1 as a starting point and the fixed toner is removed by the scraper 24 before the fixed toner interferes with the blade 23.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wet developing device using a developing solution.

[0002]

2. Description of the Related Art Conventionally, some image forming apparatuses such as copying machines and printers have adopted a wet developing device using a developing solution. The image forming system of a copying machine using such a wet developing device has been adopted. The schematic structure will be described with reference to FIG. First, a photosensitive drum 1 on which an image (latent image) is written by a light beam A emitted from an optical system (not shown) is rotatably provided, and a charger 2 is provided around the photosensitive drum 1. An eraser 3, a wet developing device 4, a transfer charger 5, a separation roller 6, a cleaning unit 7, a charge eliminating lamp 8 and the like are arranged.

A developing solution tank 9 for storing a developing solution containing toner is arranged below the wet developing device 4, and a pump 10 is provided between the developing solution tank 9 and the wet developing device 4.
A supply pipe 11 to which the developing solution is supplied by driving is provided. In the wet developing device 4, the latent image written on the outer peripheral surface of the photosensitive drum 1 is supplied to the outer peripheral surface of the photosensitive drum 1 by supplying the developer supplied from the developer tank 9 to the outer peripheral surface of the photosensitive drum 1. First and second developing rollers 12 and 13 that visualize as images, and a squeeze roller 1 that removes excess developing solution adhering to the photosensitive drum 1 after development.
And 4 are provided. Further, a recovery pipe 15 for returning the developer supplied to the wet developing device 4 and used for forming a toner image to the developer tank 9 is provided between the wet developing device 4 and the developer tank 9. It is plumbed.

The toner image formed on the photoconductor drum 1 is transferred to a transfer sheet fed from a sheet feeding section (not shown), and the transfer sheet on which the toner image is transferred is separated by a separation roller 6. After that, the copying operation is carried to a fixing section (not shown), and after being fixed by the fixing section, the sheet is discharged to a sheet discharging section (not shown) to complete the copying operation. After the transfer of the toner image onto the transfer paper, the photosensitive drum 1 is cleaned of the residual toner and paper dust by the cleaning unit 7,
In addition, the residual potential is erased by removing the electricity by the electricity removing lamp 8 to prepare for the next image writing.

The cleaning unit 7 has a sponge-like foam roller 16 and a cleaning blade 17 made of an elastic material such as rubber, which are in pressure contact with the photosensitive drum 1. Further, a supply pipe 18 to which the developing solution is supplied by driving the pump 10 is provided between the cleaning unit 7 and the developing solution tank 9, and is supplied into the cleaning unit 7 through the supplying pipe 18. The developing solution is diffused by the diffusion plate 19 over the entire width of the foam roller 16. The cleaned residual toner and paper dust are squeezed together with the developing solution by the squeeze roller 20, and the lowermost hole 21 of the cleaning unit 7 is squeezed.
Is returned to the developer tank 9 through the recovery pipe 22.

Here, the squeeze roller 14 is for removing the excess developer adhering to the photosensitive drum 1, but the squeeze roller 14 becomes extremely wet with the developer. And its performance decreases. Therefore, various means have been taken to remove the developer adhering to the squeeze roller 14, for example, a blade 23 made of urethane rubber is brought into contact with the outer peripheral surface of the squeeze roller 14. When this urethane rubber blade 23 is used, the elasticity of the urethane rubber allows the entire squeeze roller 14 to extend in the width direction even if the accuracy of the contact state of the squeeze roller 14 with the outer peripheral surface is not strictly set. It is excellent in that it can be contacted substantially uniformly.

However, when the copying machine is stopped for a long time, the squeeze roller 14 dries, and the dried and hardened toner may adhere to the outer peripheral surface of the squeeze roller 14. Toner fixed in this way (fixed toner)
Is a blade 2 made of urethane rubber when the copier is restarted.
Even if 3 interferes, it is difficult to remove it, and it can be removed only after it has been swelled and softened by the developing solution for a certain period of time after restarting. Then, copying is performed in a state where the fixed toner is fixed on the outer peripheral surface of the squeeze roller 14, so that a squeeze defect occurs (the transfer paper is partially removed because a portion of the surface of the photosensitive drum 1 where the developer is not sufficiently removed). However, there is a drawback that uneven transfer occurs due to a poor squeeze. Further, the edge portion of the urethane rubber blade 23 may be chipped when it interferes with the adhered toner, and if such chipping occurs, a line on the outer peripheral surface of the squeeze roller 14 where the developer is insufficiently removed is streaked. Occurs, and eventually causes a squeeze defect.

Therefore, as shown in FIG. 4, the blade 23
And a hard mylar having elasticity are provided as the scraper 24, and the adhered toner is removed by the scraper 24, which has been proposed and put into practical use.

The blade 23 is omitted and the scraper 2
4 is provided independently, the scraper 24 is initially used.
Removes the fixed toner and the developer from the outer peripheral surface of the squeeze roller 14. However, the scraper 24 made of Mylar easily deforms with time, and this deformation causes a portion where the scraper 24 does not come into contact with the outer peripheral surface of the squeeze roller 14, resulting in insufficient removal of the developer from the squeeze roller 14.

[0010]

By bringing the blade 23 and the scraper 24 into contact with the squeeze roller 14, the scraper 24 can effectively remove the fixed toner and the blade 23 can effectively remove the developer. Be done.

However, regarding the action of the blade 23 and the action of the scraper 24, the action of removing the fixed toner by the scraper 24 is secondarily considered mainly by the action of removing the developing solution by the blade 23. A blade 23 and a scraper 24 are arranged in this order along the rotation direction of the roller 14. Therefore, the fixed toner before interfering with the scraper 24 interferes with the blade 23, which causes a slight chipping in the edge portion of the blade 23 after repeating the copying operation of 60,000 to 120,000 sheets, and squeeze. A defect has occurred.

[0012]

The invention according to claim 1 is
An outer peripheral surface of the squeeze roller, a squeeze roller that rotates in contact with the outer peripheral surface of the photoconductor, a scraper that contacts the outer peripheral surface of the squeeze roller to remove adhered toner adhered to the outer peripheral surface of the squeeze roller. A wet developing device having a blade for contacting the squeeze roller to remove the developer adhering to the squeeze roller, from the upstream side to the downstream side in the rotation direction of the squeeze roller starting from the contact point with the photoconductor. The scraper and the blade were arranged in this order toward the.

According to a second aspect of the present invention, in the first aspect of the invention, the scraper is brought into contact with the outer peripheral surface of the squeeze roller by a counter method.

[0014]

According to the present invention, the scraper interferes with the fixed toner fixed on the outer peripheral surface of the squeeze roller to remove the fixed toner, and the blade contacts the outer peripheral surface of the squeeze roller. As a result, the developer adhering to the squeeze roller is removed. Since the scraper and the blade are arranged in order from the upstream side to the downstream side along the rotation direction of the squeeze roller starting from the contact point of the squeeze roller with respect to the photosensitive member, the scraper interferes with the scraper. It is possible to prevent the previously fixed toner from interfering with the blade, and to prevent the edge portion of the blade from being chipped.

According to the second aspect of the present invention, the scraper comes into contact with the outer peripheral surface of the squeeze roller in a counter method, so that the adhered toner can be removed very well by the scraper.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIG. The same parts as those described in FIGS. 3 and 4 are designated by the same reference numerals, and description thereof will be omitted (the same applies hereinafter). A squeeze roller 14 for contacting the outer peripheral surface of the photoconductor drum 1 as a photoconductor to remove the excess developer adhering to the photoconductor drum 1 after development is provided. The photoconductor drum 1 and the squeeze roller 14 is set to rotate in the same direction. Therefore, the photosensitive drum 1 and the squeeze roller 14 are in contact with each other at their contact points while moving in opposite directions.

Next, a scraper 24 and a blade 23, which are in contact with the outer peripheral surface of the squeeze roller 14, are provided. The blade 23 is made of urethane rubber which is a soft member, and the scraper 24 is made of this urethane rubber. Is also formed by Mylar having high hardness. Further, the scraper 24 and the blade 23 are directed from the upstream side to the downstream side along the rotation direction of the squeeze roller 14 starting from the contact point where the squeeze roller 14 contacts the outer peripheral surface of the photosensitive drum 1. Are arranged in order, and the intervals are set small. Further, both the scraper 24 and the blade 23 are in contact with the outer peripheral surface of the squeeze roller 14 by a counter method.

In such a structure, when the copying machine is restarted from the state where the fixed toner is fixed on the outer peripheral surface of the squeeze roller 14 because the copying machine is stopped for a long time,
The photosensitive drum 1, the squeeze roller 14, etc. rotate in the directions of the arrows, and the fixed toner fixed on the outer peripheral surface of the squeeze roller 14 first interferes with the scraper 24.

Then, the adhered toner interferes with the scraper 24, so that the adhered toner is removed from the outer peripheral surface of the squeeze roller 14, or even if the adhered toner is not completely removed at the time of the first interference, the surrounding toner is angular. The part is cut. Therefore, the interference of the fixed toner with the blade 23 is significantly reduced, and even if the interference occurs, the fixed toner in a smooth state in which the angular portion is scraped interferes. Therefore, the occurrence of chipping at the edge portion of the blade 23 caused by the blade 23 interfering with the fixed toner is prevented, and the occurrence of chipping at the edge portion of the blade 23 is prevented.
The removal of the developing solution by 3 is performed well over a long period of time.

Note that the scraper 24 repeats the interference with the fixed toner to cause a change over time to form a portion that does not come into contact with the outer peripheral surface of the squeeze roller 14, but the fixed toner in a state of being raised from the outer peripheral surface of the squeeze roller 14. Interference still occurs. Therefore, the removal of the adhered toner by the scraper 24 can be satisfactorily performed even after the scraper 24 has changed over time.

Table 1 shows the present embodiment (scraper 2
4, the blade 23 is arranged in this order) and three conventional examples (when the blade 23 is provided alone, when the scraper 24 is provided alone, when the blade 23 and the scraper 24 are arranged in this order), the squeeze roller 14 6 shows the results of comparison of observing the dirty state of the outer peripheral surface and the chipped state of the edge portion of the blade 23. The blade 23
The chipped state is that the presence or absence of the chipped portion is checked by observing the edge portion of the blade 23 with a magnifying glass. Further, the stain on the outer peripheral surface of the squeeze roller 14 occurs when the removal of the developing solution by the blade 23 is insufficient, and the stain ranks 5 to 1 are determined based on the following criteria. Rank 5: There is no stain on the outer peripheral surface and no streaky stain. Rank 4: No stain on the outer peripheral surface, but 1 to 2 streaky stains
I have a book. Rank 3: Toner is slightly attached to the outer peripheral surface, and 3 to 6 streaky stains are present. Rank 2: Toner is slightly attached to the outer peripheral surface, and 7 to 10 streaky stains are present. Rank 1: Adhesion of toner is noticeable on the outer peripheral surface, and there are 11 or more streaky stains.

[0022]

[Table 1]

As can be seen from Table 1, by arranging the scraper 24 and the blade 23 in this order, the scraper 2
Since the adhered toner is satisfactorily removed by means of No. 4, chipping of the edge portion of the blade 23 does not occur, and therefore the removal of the developer adhering to the outer peripheral surface of the squeeze roller 14 by the blade 23 is satisfactory for a long period of time. The squeeze defect does not occur, and a good image can be obtained when transferred to a transfer paper.

Also, the squeeze roller 1 of the scraper 24
Since the contact with 4 is performed by the counter method, the scraped toner can be removed very well by the scraper 24.

Next, a second embodiment of the present invention will be described with reference to FIG. In this embodiment, the scraper 24 is brought into contact with the outer peripheral surface of the squeeze roller 14 by a counter method, and the blade 23 is trailed by a squeeze roller 1.
4 is brought into contact with the outer peripheral surface of No. 4.

Although the gap between the scraper 24 and the blade 23 is large, as in the first embodiment,
The squeeze rollers 14 are arranged in order from the upstream side to the downstream side along the rotation direction of the squeeze rollers 14 starting from the contact point where the squeeze rollers 14 contact the outer peripheral surface of the photosensitive drum 1.

In this embodiment, as in the case of the first embodiment, the scraped toner is satisfactorily removed by the scraper 24 so that the blade 23 is not chipped. The developer adhering to the outer peripheral surface of the squeeze roller 14 is satisfactorily removed by the squeeze roller 23 for a long period of time, a squeeze defect does not occur, and a good image is obtained when transferred to the transfer paper.

Further, since the blade 23 is brought into contact with the squeeze roller 14 by the trailing method, even if the fixed toner interferes with the blade 23, an unreasonable force acts on the blade 23. Is prevented, the occurrence of chipping in the blade 23 is further prevented, and the durability of the blade 23 is further lengthened.

[0029]

As described above, the squeeze roller that rotates in contact with the outer peripheral surface of the photoconductor and the outer peripheral surface of the squeeze roller that contacts the outer peripheral surface of the squeeze roller as described above. In a wet developing device having a scraper for removing adhered toner adhered to the squeeze roller, and a blade for contacting the outer peripheral surface of the squeeze roller to remove the developer adhering to the squeeze roller, Since the scraper and the blade are arranged in this order from the upstream side to the downstream side along the rotation direction of the squeeze roller as the starting point, the scraper is first attached to the fixed toner fixed on the outer peripheral surface of the squeeze roller. The interference causes the adhered toner to be removed from the outer peripheral surface of the squeeze roller, or the angled portion to be scraped off. The interference of the adhered toner can be reduced and the interference of the adhered toner in an angular state can be prevented. Therefore, it is possible to prevent the occurrence of chipping of the edge portion of the blade caused by the interference of the adhered toner with the blade. As a result, the squeeze defect can be prevented from occurring, and a good image can be obtained when transferred to the transfer paper.

According to a second aspect of the invention, in the first aspect of the invention, the scraper is brought into contact with the outer peripheral surface of the squeeze roller by a counter method, so that the adhered toner can be removed very well by the scraper, Therefore,
It is possible to further prevent the occurrence of chipping of the edge portion of the blade caused by the adhered toner interfering with the blade, and it is possible to improve the durability of the blade.

[Brief description of drawings]

FIG. 1 is a front view showing a first embodiment of the present invention.

FIG. 2 is a front view showing a second embodiment of the present invention.

FIG. 3 is a front view showing a schematic structure of an image forming system in a copying machine including a conventional wet developing device.

FIG. 4 is a front view showing another conventional wet developing device.

[Explanation of symbols]

 1 Photoconductor 14 Squeeze Roller 23 Blade 24 Scraper

Claims (2)

[Claims] 1. A squeeze roller that rotates in contact with the outer peripheral surface of a photoreceptor, a scraper that contacts the outer peripheral surface of the squeeze roller to remove the fixed toner adhered to the outer peripheral surface of the squeeze roller, and In a wet type developing device having a blade that comes into contact with the outer peripheral surface of the squeeze roller and removes the developer adhering to the squeeze roller, along the direction of rotation of the squeeze roller starting from the point of contact with the photoconductor. A wet developing device in which the scraper and the blade are arranged in this order from the upstream side to the downstream side. 2. The scraper is brought into contact with the outer peripheral surface of the squeeze roller by a counter method.
The wet developing device described.