JPH0850416A - Developing device - Google Patents

Abstract

PURPOSE:To prevent the overflowing of a liquid developer and deficiency in the supply of the developer by excellently maintaining the flowability of the developer between the upstream side in the rotational direction of a developing roller which corresponds to the recovering side of the developer and the downstream side in the rotational direction of the developing roller which corresponds to the supplying side of the developer to the developing roller, with an interposed blade scraping the surplus liquid developer from the developing roller after development processing, even if a high viscosity liquid developer is used. CONSTITUTION:This developing device is constituted in such a manner that an opening part, 11A used as a flow passage for the liquid developer is provided on a blade holding member 11 holding the blade 10 being abutted on the developing roller 4 to supply the developer to a latent image carrier 1 and then, scraping the surplus liquid developer remaining on the surface of the developing roller 4, so that the developer freely flows from the recovering part of the developer to a supplying part without receiving resistance by the blade 10 and the blade holding member 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device in an image forming apparatus, and more particularly to a structure of a cleaning blade used to scrape off excess developer remaining on the surface of a developing roller.

[0002]

2. Description of the Related Art Generally, as a developing device used in an image forming apparatus such as a printer or an electrophotographic apparatus, there are a dry developing device using a dry developer and a wet developing device using a liquid developer. The wet developing device includes a liquid developer (hereinafter, referred to as “developer”) in which toner forming charged particles is dispersed in a solvent.
Is used. In this wet-type developing device, the electrostatic attraction of the electrostatic latent image formed on the surface of the photoconductor forming the latent image carrier causes the electrostatic attraction of the toner particles in the solvent to electrostatically attract the toner particles to the electrostatic latent image. By doing so, visible image processing is performed. The developing solution supplied to the photoconductor is adjusted in necessary amount so that it is adsorbed only to the latent image. For this adjustment, a doctor contacting the surface of the developing roller is adjusted. A member is used.

The developing roller, which has finished supplying the developing solution to the electrostatic latent image, is adapted to remove the excess developing solution remaining on the surface without being used for development. The excess developer is removed in order to restore the surface state of the developing roller to the initial state, whereby the homogeneity of the developer film when it is carried again on the surface of the developing roller is maintained.

As a structure for removing the excess developing solution after supplying the developing solution, there is known a structure in which a blade is brought into contact with the surface of the developing roller as described in Japanese Utility Model Laid-Open No. 60-104251. There is. FIG. 6 is a diagram showing a conventional example of a developing device having a configuration using the above-mentioned blade. In FIG. 6, reference numeral 1 denotes a photosensitive drum which is a latent image carrier. The photosensitive drum 1 is of this kind,
As in the case of the electrophotographic image forming apparatus, an electrostatic latent image corresponding to the original image is formed on the uniformly charged photoconductive layer by the exposure process, and the electrostatic latent image is developed. The visible image processing is performed by bringing the liquid into contact.

The developing device 2 provided for supplying the developing solution to the electrostatic latent image includes a developing tray 3 disposed in the vicinity of the photosensitive drum 1 and a developing tray housed in the developing tray 3. Developing roller 4, a part of which is immersed in the liquid, developing roller 4
And a doctor roller 5 that regulates the film thickness of the developer carried on the surface of the developing roller 4, and a scraper 6 that abuts the surface of the doctor roller 5 and scrapes the collected developer from the developing roller 4. Placed in the developing tray 3,
The blade 7 is in contact with the surface of the developing roller 4. As shown in FIG. 6 (B), the blade 7 includes a rubber blade main body 7A having a longitudinal direction parallel to the longitudinal direction of the developing roller, and a blade holding member having the blade main body 7A attached to the tip thereof. It is composed of a member 7B. The developing roller 4 and the doctor roller 5 are
Each of them can rotate in the direction of the arrow shown, and the developer carried on the developing roller 4 is regulated to have a predetermined film thickness.

In the developing device 2, the developing solution is carried on the surface of the developing roller 4 which is partially immersed in the developing tray 3, and the film thickness of the developing solution is regulated by the doctor roller 5 as described above. A developing solution is brought into contact with the electrostatic latent image on the body drum 2 to form a visible image. After the supply of the developing solution to the electrostatic latent image is completed, the blade 7 collects the excess developing solution remaining on the surface.

[0007]

By the way, the developer used for the visible image processing of the electrostatic latent image has a certain degree of viscosity, and a low viscosity developer of less than 1 cst is used.
In some cases, a highly viscous developing solution of about 1 to 50 cst is used, and the fluidity of the developing solution is different in each case. In the case of low viscosity developer, it has relatively good fluidity,
When the blade 7 is scraped off, it can flow smoothly from the upstream side to the downstream side in the rotation direction of the developing roller 4 by sandwiching the blade 7, so that the liquid level in the developing tray 3 is above the upstream side. And the same level can be maintained on the downstream side. On the other hand, in the case of the high-viscosity developer, since the fluidity is considerably poor, a smooth flow from the upstream side to the downstream side cannot be obtained, and the developer tends to aggregate on the upstream side. Therefore, as shown by the arrow in FIG. 6 (B), even if the side edge of the blade 7 flows around, the speed of the flow from the upstream side to the downstream side tends to be slow, which causes the upstream side to flow. There is a risk that the liquid level of # 1 may rise extremely and the developer may overflow from the developing tray 3, or the supply of the developer to the developing roller 4 on the downstream side may be insufficient.

The object of the present invention is, even when a high-viscosity developing solution is used, the upstream side in the rotational direction of the developing roller 4 corresponding to the developer collecting side across the blade and the developing roller 4.
It is possible to prevent the overflow of the developing solution and the insufficient supply of the developing solution by maintaining good fluidity of the developing solution between the developing solution and the downstream side in the rotation direction of the developing roller 4 corresponding to the supplying side of the developing solution. The object is to provide a developing device that can do so.

[0009]

To achieve this object, the invention according to claim 1 is a wet developing apparatus using a liquid developer, and a developing roller for supplying the liquid developer to the latent image carrier, A blade that comes into contact with the developing roller and supplies the liquid developer to the latent image carrier, and scrapes off the excess liquid developer remaining on the surface of the developing roller; and a blade holding member that holds the blade, It is characterized in that the blade holding member is provided with an opening serving as a flow path of the liquid developer.

According to a second aspect of the present invention, in a wet developing apparatus using a liquid developer, a developing roller for supplying the liquid developer to the latent image carrier and a developing roller which is in contact with the developing roller and is applied to the latent image carrier. After supplying the liquid developer, a blade for scraping off the excess liquid developer remaining on the surface of the developing roller and a blade holding member for holding the blade are provided, and the excess liquid developer is developed on the blade holding member. It is characterized in that a forced circulation means for forcibly circulating the roller away from the roller side is provided.

According to a third aspect of the present invention, in a wet type developing apparatus using a liquid developer, a developing roller for supplying the liquid developer to the latent image carrier and a developing roller which is in contact with the developing roller and is applied to the latent image carrier. After supplying the liquid developer, a blade for scraping off the excess liquid developer remaining on the surface of the developing roller, and a blade holding member for holding the blade are provided, and the blade can be brought into contact with and separated from the surface of the developing roller. It is characterized by being provided.

According to a fourth aspect of the present invention, in a wet developing device using a liquid developer, a plurality of developing rollers for supplying the liquid developer to the latent image carrier and a plurality of developing rollers are arranged in the circumferential direction of the developing roller. An end portion of the blade is in contact with the developing roller, and after the liquid developer is supplied to the latent image carrier, a blade for scraping off the excess liquid developer remaining on the surface of the developing roller, and a blade holding member for holding the blade are provided. The plurality of blades are characterized in that the flow paths of the liquid developer are arranged in a zigzag pattern along the longitudinal direction of the developing roller.

[0013]

According to the first aspect of the invention, the liquid developer scraped off from the developing roller passes directly from the recovery side to the supply side through the opening without receiving resistance from the blade.

According to the second aspect of the invention, the liquid developer is forcibly moved from the recovery side toward the supply side.

According to the third aspect of the invention, the state of scraping the excess liquid developer from the developing roller and the state of circulation of the excess liquid developer are set.

According to the fourth aspect of the present invention, the blades are arranged in a staggered arrangement along the longitudinal direction of the developing roller to secure a scraping range in the longitudinal direction, and the liquid developer resists in the scraping range. Circulate without.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described with reference to the embodiments shown in the drawings.

FIG. 1 is a schematic view for explaining the main structure of the first embodiment of the developing device according to the present invention. 1 and subsequent drawings, the same components as those shown in FIG. 6 are designated by the same reference numerals, and detailed description thereof will be omitted. In FIG. 1, inside the developing tray 3, there is a blade 1 that contacts the developing roller 4.
0 is provided. The blade 10 has a length that is substantially the same as the axial length of the developing roller 4, and the tip thereof is the developing roller 4.
The lower end side is attached to the tip of the blade holding member 11. The blade holding member 11 has substantially the same length as the blade 10 and is made of a metal plate having mechanical rigidity, and has an opening 11A formed of a plurality of square holes along its longitudinal direction. Opening 11A
Penetrates in the thickness direction of the blade holding member 11, but penetrates in the horizontal direction with respect to the installation angle of the blade holding member 11. Thereby, the blade holding member 11
The edge portion at the edge of the opening that is formed when the opening is formed by penetrating in the thickness direction of the developing solution is set so that the smooth inflow of the developer and the laminar flow state are set. When the opening is penetrated in the thickness direction of the blade holding member 11, the edge of the opening is inclined, and when the developing solution flows into the opening,
The developer is entrained behind the opening edge on the inflow side of the developer to generate a turbulent flow.

The size and number of the openings 11A are preferably as large as possible within a range that does not adversely affect the rigidity of the blade holding member 11 in order to secure a large flow passage.

Since this embodiment has the configuration as described above,
The developing roller 4, which has supplied the developing solution to the electrostatic latent image formed on the photosensitive drum 2, is scraped off by the blade 10 after the developing solution is supplied. Blade 10
The developing solution scraped off by the blade 10 flows across the blade 10 from the upstream side to the downstream side of the developing roller 4. At this time, the developer does not bypass the side end of the blade holding member 11 but directly enters the opening 11A. This allows
Rotational direction of the developing roller 4 corresponding to the developer collecting side sandwiching the blade 10 without decreasing the flowing-in speed when scraped off. Rotating direction of the developing roller 4 corresponding to the developing solution supplying side from the upstream side. It flows to the downstream side. When entering the opening 11A, the developer can move in the horizontal direction depending on the penetrating direction of the opening 11A as shown by the arrow in FIG. Therefore, it is possible to prevent the staying in the vicinity of the blade.

According to this embodiment, the developing solution scraped from the developing roller 4 flows from the collecting side of the developing solution to the supplying side without suppressing the force of the scraping and flowing into the developing tray 3. Therefore, the developer is prevented from aggregating on the collecting side, and the liquid levels of the collecting side and the supplying side can be matched. The structure of the above-mentioned opening is as shown in FIG.
As shown in (D), it is also possible to make it into a mortar shape so that the inflow of the developing solution can be carried out more smoothly. The present inventor conducted an experiment using a highly viscous developing solution of 30 cst as a developing solution. As a result, no aggregation of the developing solution was found on the collecting side of the developing solution in the developing tray 3, and the collecting side and the supplying side were not observed. The results of matching the liquid level were obtained. The developing tray 3
The replenishment of the developing solution to the is carried out through a pipe extending from a developing tank (not shown), and therefore a pump (not shown) for feeding the developing solution is provided in the middle of the pipe. There is. Incidentally, the replenishment of the developing solution to the developing tray 3 and the viscosity of the developing solution to be used are the same in the examples described below unless otherwise specified.

Next, a second embodiment of the developing device according to the present invention will be described with reference to FIG.

The present embodiment is characterized in that the developing solution scraped from the developing roller is forced to flow from the collecting side to the supplying side. The blades 12 that come into contact with the developing roller 4 are fixed to the respective tips of blade holding members 13 that are attached along the peripheral surface of the rotary shaft 14. The rotary shaft 14 constitutes a forced circulation means that can rotate counterclockwise in FIG. 2A by a drive mechanism (not shown). The blade 12 integrated with the blade holding member 13 provided on the rotating shaft 14 is provided with a space for forming a passage for the developing solution between the blade 12 and the inner surface of the bottom wall of the developing tray 3. It is arranged. As a result, the blade 12 constitutes a rotary blade by the aggregate. The rotary blade constituted by the assembly of the blades 12 is rotated at a speed at which the developing solution scraped from the developing roller 4 is directly transferred to the developing solution supply side while sandwiching the rotary blade. ing.

Since this embodiment has the above-mentioned structure,
The developing roller 4, which has supplied the developing solution to the electrostatic latent image formed on the photosensitive drum 2, is scraped off by the blade 12 after the developing solution is supplied. Developing roller 4
The rotation shaft 14 starts to rotate from the point when the rotation starts, and the rotary blade composed of the assembly of the blades 12 rotates counterclockwise in FIG. 2A.

As shown by the arrow in FIG. 2 (A), the developer scraped off by the blade 10 flows into the upstream side in the rotation direction of the developing roller 4 corresponding to the developer collecting section by sandwiching the rotary blades. As it is, it is transferred by the rotary blade to the downstream side in the rotation direction of the developing roller 4, which corresponds to the supply portion of the developing solution, through the passage formed below the rotary blade. As a result, the developer collecting side, where the scraped developer is likely to accumulate and the liquid level tends to rise, moves to the supply side as it is, so the liquid level is almost the same as the supply level. Maintained at.

According to this embodiment, the liquid level on the recovery side of the developer, which tends to aggregate with the developer scraped off from the developing roller, can be made equal to the liquid level on the supply side of the developer. It is possible to prevent overflow of the developing solution on the collecting side and shortage of the developing solution on the supply side. The developing solution used in this example is a highly viscous developing solution of 30 cst as in the first example. When an experiment was conducted using this developing solution, it was found that the developer overflowed on the recovery side and the supply side. No shortage of developer was observed.

Next, a third embodiment of the developing device according to the present invention will be described with reference to FIGS.

The present embodiment is characterized in that the blade is changed between a state in which the developing solution is scraped from the developing roller and a state in which a flow path from the recovery side of the developing solution to the supply side is formed. The blade 15 is attached to the tip of the blade holding member 16. The blade holding member 16 is a swingable member whose base end side is attached to the support shaft 17, and supports the blade 15 with respect to the developing roller 4 so that the blade 15 can be moved toward and away from the developing roller 4.
When the blade 15 comes into contact with the developing roller 4, it corresponds to when scraping off the excess developing solution from the developing roller 4.
When 5 is separated from the developing roller 4, it corresponds to when a flow path of the developing solution is formed between the developing roller 4 and the tip of the blade 15.

The blade 15 has a leading edge of the image forming area from the time when the trailing edge of the image forming area in the circumferential direction of the photosensitive drum 1 passes through a transfer step, which is one of the image forming steps of the electrophotographic system. Until just before facing the developing roller 4, as shown in FIG. 4, the developing solution is separated from the developing roller 4 and a flow path of the developing solution is formed below the peripheral surface of the developing roller 4. Therefore, as shown in FIG. 3, the blade 15 is provided from immediately before the front end of the image forming area in the circumferential direction of the photosensitive drum 1 faces the developing roller 4 to when the rear end of the image forming area passes through the transfer process section. Developing roller 4
To scrape off the excess developing solution.

Since this embodiment has the above-mentioned configuration,
The developing roller 4, which has supplied the developing solution to the electrostatic latent image formed on the photoconductor drum 2, is scraped off by the blade 15 after the developing solution is supplied. Developing roller 4
The developer scraped off from the blade is sandwiched by the blade 15 and collected on the upstream side in the rotation direction of the developing roller 4, which corresponds to the developer collecting side.

On the other hand, the blade 15 separates from the developing roller 4 when the trailing edge of the image forming area passes through the transfer process section. As a result, below the developing roller 4, the blade 15 is sandwiched between the upstream side in the rotation direction of the developing roller 4, which corresponds to the collecting side of the developing solution which has been partitioned by the blade 15, and the supplying side of the developing solution. Since the flow path of the developing solution is formed by communicating with the downstream side in the rotation direction of the developing roller 4, the developing solution accumulated in the collecting side flows into the supplying side.

According to the present embodiment, only by changing the contact state of the blade 15 with the developing roller 4, the developer collecting side and the supplying side are communicated with each other to form the flow path of the developing solution. It is possible to make the liquid surfaces of the developer on the supply side and the supply side coincide with each other. The timing of contact and separation of the blade 15 is
Instead of using the image forming area of the photoconductor drum 1 as a reference, the contacting / separating operation may be repeated at a predetermined timing.

Next, a fourth embodiment of the developing device according to the present invention will be described with reference to FIG. This embodiment is characterized in that the flow path of the developing solution can be formed even when a plurality of blades are used. The blade is shown in FIG.
The first blade 18 and the second blade 1 as shown in FIG.
9 and 9 are arranged in parallel along the circumferential direction of the developing roller 4. As shown in FIG. 5 (B), the first and second blades 18 and 19 are formed in a comb-tooth shape having a plurality of recesses 18A and 19A at predetermined intervals along the longitudinal direction. These blades have such a length that they can face each other in the entire axial direction of the developing roller 4 by the mutual blades. This allows the developing roller 4 to contact the blade over the entire axial direction. Recesses 18A, 19A in the first and second blades 18, 19
As shown in FIG. 5 (C), the blades are formed in a staggered pattern with their phases shifted with respect to each blade, and the recesses of one blade communicate with the recesses of the other blade.

These first and second blades 18 and 19
Is attached to the tip of the blade holding member 20 fixed in the developing tray 3.

Since this embodiment has the above-mentioned configuration,
The developing roller 4, which has supplied the developing solution to the electrostatic latent image formed on the photoconductor drum 2, supplies the developing solution, and then supplies the developing solution to the excess developing solution over the entire axial direction by the first and second blades 18 and 19. Be scraped off. The developing solution scraped off from the developing roller 4 flows between the first and second blades 18 and 19 and flows into the upstream side in the rotational direction of the developing roller 4 corresponding to the collecting side of the developing solution, and the first blade 18 Passes through the recess 18A. The developer that has passed through the concave portion 18A of the first blade 18 becomes the concave portion 19A of the second blade 19.
After passing through the inside, as shown by the arrow in FIG. 5 (C), it flows into the downstream side in the rotation direction of the developing roller 4, which corresponds to the supply side of the developing solution, across the blade.

According to this embodiment, even when the excess developing solution remaining on the developing roller 4 is scraped by a plurality of blades, the blades of the scraped developing solution are simply formed in each blade. The developer can be made to flow from the recovery side to the supply side without receiving resistance from the blade. Thus, when the blade is regarded as a weir, even if there are a plurality of weirs, the developer accumulated on the recovery side can be made to flow to the supply side so that the liquid levels of the developer are the same on the recovery side and the supply side. It will be possible. The blade is not limited to the comb-teeth shape, but a plurality of single blades may be arranged in parallel along the axial direction of the developing roller 4 so as to have the same function as the comb-teeth. Is.

In the present embodiment, the first and second blades 18 and 19 are arranged side by side, but the bases of these blades are integrated with each other so that the blade tip is formed as described above. It is also possible to arrange in parallel as in the example.

[0038]

As described above, according to the first aspect of the invention, the developer scraped from the developing roller is directed from the collecting side to the supplying side through the opening without receiving resistance from the blade. Because you can go through directly,
It is possible to prevent overflow of the liquid developer on the recovery side and shortage of the liquid developer on the supply side.

According to the second aspect of the present invention, the liquid developer can be forcibly moved from the recovery side toward the supply side, so that the liquid developer that tends to rise in liquid level on the recovery side is supplied. It is possible to pour it to the side and make the liquid level on both sides the same.

According to the third aspect of the present invention, since the state of scraping the excess liquid developer from the developing roller and the state of circulation of the excess liquid developer are set, the liquid developer from the collecting side to the supplying side is set. It is possible to prevent the liquid level on the recovery side from rising abnormally by allowing the flow of the liquid.

According to the fourth aspect of the invention, the blades are arranged in a staggered arrangement along the longitudinal direction of the developing roller to secure a scraping range in the longitudinal direction, and the developing solution is kept in the scraping range. Since the liquid can flow without resistance, the scraping range in the longitudinal direction can be secured, and even when a plurality of blades are installed, the liquid surface level can be made to match between the recovery side and the supply side. This makes it possible to prevent overflow of the liquid developer on the recovery side and shortage of the liquid developer on the supply side.

[Brief description of drawings]

1A and 1B are schematic views for explaining a configuration of a main part of a developing device according to a first exemplary embodiment of the present invention, in which FIG. 1A shows an overall structure of the main part, and FIG. 2C shows the appearance, FIG. 7C shows a cross section taken along the arrow C in FIG. 8B, and FIG. 8D shows a modified example of the opening.

2A and 2B are schematic views for explaining a configuration of a main part of a second embodiment of the developing device according to the present invention, FIG. 2A shows an overall structure of the main part, and FIG. Shows the appearance of.

FIG. 3 is a schematic diagram for explaining a main part configuration of a developing device according to a third embodiment of the present invention.

FIG. 4 is a schematic diagram for explaining one aspect of the configuration of the main parts shown in FIG.

5A and 5B are schematic diagrams for explaining a configuration of a main part of a developing device according to a fourth embodiment of the present invention, in which FIG. 5A shows the overall structure of the main part, and FIG. And (C) shows the appearance from the direction indicated by the symbol C in (B).

6A and 6B are schematic diagrams for explaining a conventional example of a developing device, in which FIG. 6A shows the overall configuration, and FIG. 6B shows the appearance of a blade used in the overall configuration shown in FIG. .

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Photoconductor drum 2 Developing device 10, 12, 15, 18, 19 Blade 11, 13, 16, 20 Blade holding member 11A Opening 14 Rotating shaft which constitutes forced circulation means 17 Spindle for supporting the blade in contact with and separating from each other 18A, 19A Recesses forming staggered flow paths

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Takayoshi Kudo Inventor Takayoshi Kudo, Shibata-cho, Shibata-gun, Miyagi Prefecture Nakameisei 3 Shinmeido, Tomei Ricoh Co., Ltd. (72) Inventor Akihiro Ito Nakata, Shibata-machi, Shibata-gun, Miyagi Prefecture Inside the Tohoku Ricoh Co., Ltd.

Claims (4)

[Claims] 1. In a wet developing device using a liquid developer, a developing roller for supplying the liquid developer to the latent image carrier, and a developer roller which is in contact with the developing roller and is supplied to the latent image carrier. A blade for scraping off excess liquid developer remaining on the surface of the developing roller; and a blade holding member for holding the blade, wherein the blade holding member is provided with an opening serving as a flow path for the liquid developer. A developing device characterized by the above. 2. In a wet developing device using a liquid developer, a developing roller for supplying the liquid developer to the latent image carrier, and a developer roller which is in contact with the developing roller and supplies the liquid developer to the latent image carrier. A blade for scraping off the excess liquid developer remaining on the surface of the developing roller, and a blade holding member for holding the blade, wherein the blade holding member is provided with the excess liquid developer in a direction away from the developing roller side. A developing device comprising a forced circulation means for forcibly circulating. 3. A wet developing device using a liquid developer, a developing roller for supplying the liquid developer to the latent image carrier, and a developer roller contacting the developing roller for supplying the liquid developer to the latent image carrier, A blade for scraping off excess liquid developer remaining on the surface of the developing roller; and a blade holding member for holding the blade, wherein the blade is provided so as to be able to come into contact with and separate from the surface of the developing roller. Characteristic developing device. 4. A wet developing device using a liquid developer, a developing roller for supplying the liquid developer to a latent image carrier, and a plurality of developing rollers arranged along the circumferential direction of the developing roller, the ends of which are the developing roller. A blade for scraping off the excess liquid developer remaining on the surface of the developing roller after the liquid developer is supplied to the latent image carrier, and a blade holding member for holding the blade. Is a developing device in which the flow paths of the liquid developer are arranged in a zigzag pattern along the longitudinal direction of the developing roller.