JPS61286868A - Developing solution supplying device - Google Patents

Abstract

PURPOSE:To preliminarily annihilate foam and to obtain a uniform image by once storing a developing soln. in a region where developing roller and scrapers face each other and supplying the developing soln. stored therein to a latent image carrying body while scooping up the developing soln. in a liquid film state according to the rotation of the developing rollers. CONSTITUTION:The respective top ends of the scrapers 131A, 132A which are fixed at the root ends thereof to a developing container 130 are in press contact with the 1st and 2nd developing rollers 131, 132 in such a manner that the soln. can be stored. These scrapers clean the toners on the developing rollers at all times. A soln. supplying nozzle 20 is then disposed in the position where an aperture 20a thereof faces the root end side of the scraper 131A in proximity thereof to decrease the generation of the foam by splashes, etc. when the soln. flows into the liquid reservoir. The developing soln. once forming the liquid reservoir is supplied successively via the developing rollers to a photosensitive drum 10 and is supplied uniformly thereto via the developing rollers. The foam is thereby annihilated and the uniform image quality is easily obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a developer supply device, and more specifically, a developer supply device that can be widely applied to image forming apparatuses that employ a wet development method, such as electrophotographic copying machines and facsimile machines. It is related to.

(Prior art) In a wet development method in which a developing solution is supplied to the circumferential surface of a photoreceptor drum carrying an electrostatic latent image to visualize the electrostatic latent image, as a means for supplying the developing solution, for example, JP-A No. Showa 57-200
There is a technique disclosed in Japanese Patent No. 56.

In this method, the liquid injected from a developer supply nozzle first hits a guide plate, then flows down along this guide plate, reaches the photoreceptor drum, and is further applied to the circumferential surface of the photoreceptor drum. The liquid then flows down and forms a pool between the developing roller and the photosensitive drum.

Further, as another developer supplying means, a configuration as shown in FIG. 4 can be considered.

In this method, the opening 3 of the developer supply nozzle is arranged above the area where the photoreceptor drum 1 and the developing roller 2 face each other. Therefore, the developer discharged from the opening 3 directly forms a liquid pool in the area where the photoreceptor drum 1 and the developing roller 2 face each other. Note that the position of the opening 3 in the longitudinal direction of the photosensitive drum shaft is at the center as shown in FIG.

In each of these conventional techniques, an attempt is made to uniformly supply the developer stored in the liquid reservoir to the circumferential surface of the photoreceptor drum through a narrow gap between the photoreceptor drum 1 and the developing roller.

By the way, in the above-mentioned conventional technology, the developer discharged from the opening 3 contains bubbles due to air contained in the tube especially at the time of startup, and bubbles also occur when the developer deteriorates. There is a characteristic that it is easy to occur. In addition to this, by being ejected forcefully from the opening 3,
Alternatively, due to the contact with the guide plate, many air bubbles are present in the liquid pool between the photoreceptor drum and the developing roller, and these air bubbles significantly reduce the developing performance and impair the image quality. There is.

Further, as shown in FIG. 5, the amount of liquid pooled is large only near the opening 3, and the amount of liquid pooled tends to decrease as the distance from the opening 3 increases. For this reason, if the amount of liquid supplied from the opening 3 is increased, the pump will be burdened and generate heat, causing the temperature of the developer to rise.In addition, a large amount of the developer will spill directly onto a part of the photoreceptor, resulting in a uniform You will not be able to obtain a clear image. That is, an imbalance occurs in the amount of developer supplied in the vicinity of the opening 3 and a portion away from it, causing unevenness in image density.

(Objective) Therefore, an object of the present invention is to provide a developer solution that can eliminate air bubbles mixed in the developer solution in advance by a simple means, and can evenly supply the developer solution to the peripheral surface of a latent image carrier. The goal is to provide equipment.

(Structure) In order to achieve the above object, the present invention disposes a developing roller in close proximity to the latent image carrier, a scraper is brought into pressure contact with the developing roller so as to be able to collect liquid, and the developing roller and the scraper are opposed to each other. This system is characterized in that a developer is temporarily stored in a region, and as the developing roller rotates, the stored developer is drawn up in the form of a liquid film and supplied to the latent image carrier.

Hereinafter, a detailed explanation will be given based on one embodiment of the present invention.

The example described below is for a transfer-type electronic copying machine, in which an electrostatic latent image on a photoreceptor is developed by a developing row that is rotated and driven at a minute interval from a latent image carrier, such as a photoreceptor drum. The developing roller is developed with a liquid, and the developing roller is cleaned with a scraper that also serves as a liquid reservoir.

The following explanation will be given using an example in which the photoreceptor is shaped like a drum as a latent image carrier. However, the photoreceptor is not limited to this; the photoreceptor can also be shaped like a belt, or a dielectric material can be used instead of the photoreceptor in the form of a drum. Alternatively, it can also be configured in a belt shape.

First, we will outline the copying process.

In FIG. 1, during copying, the photosensitive drum 10 is driven to rotate at a constant speed in the direction of the arrow (clockwise) by a drive device, and after being uniformly charged by a main charger 11, a document image IN is projected by an exposure device. An electrostatic latent image is formed on the photoreceptor, and the area outside the image forming area is eliminated by the eraser 12.

The electrostatic latent image on the photosensitive drum IO is visualized by a wet developing device 13 to which the present invention is applied, and is fed from a paper feeding device (not shown) via a conveyance roller 14 as indicated by a broken line arrow. The image is transferred onto the transfer paper S by the transfer charger 15.

This transfer paper S is separated from the photosensitive drum 1 by a separation roller 16.
0 and is conveyed by a conveyor belt 17, and hereafter,
The toner is fixed by the fixing device and discharged to the outside.

After the transfer paper S is separated from the photosensitive drum 10, residual toner is removed by a cleaning unit 18, residual potential is removed by a static eliminator lamp 19 (static eliminator or static eliminator charger), and the photosensitive drum 10 is prepared for the next copying.

The above is an overview of the copying process.The above-mentioned wet type developing device i13 to which the present invention is applied will be described.

Wet developing device! ! 13, a first developing roller 131 and a second developing roller 132 are installed in the developing container 130 in order from the top.
and a squeeze roller 133 are each pivotally supported.

1st. The second developing rollers 131 and 132 are each held at a small distance from the surface of the photosensitive drum 10. This interval is adjusted to, for example, 0.1 m, and the photosensitive drum 10 is rotated in a direction opposite to that of the photosensitive drum 10 (counterclockwise) as shown by an arrow by a drive device (not shown). Further, a scraper 13 whose base end is fixed to the developer container 130
1A and 132A, each tip of the first. They are in pressure contact with the second developing rollers 131 and 132 so as to be able to collect liquid, respectively, and are designed to constantly clean the toner on the developing rollers.

Here, the term "pressure-contacted so as to allow a liquid reservoir" means that a scraper having a length in the longitudinal direction of the axis of the developing roller has a free end thereof in a substantially V-shaped opposing area in relation to the circumferential surface of the developing roller. so as to form, and.

This means setting the developer solution so that it can be stored in the area opposite thereto. Therefore, the developer is stored in the facing area6.Therefore, hereinafter, the developer stored in the facing area will be referred to as a liquid reservoir.

Next, the opening 20a of the liquid supply nozzle 20 is positioned so as to supply the developer without creating bubbles in the liquid reservoir.

As shown in FIG. 1, the scraper 131A is arranged close to and opposite to the base end side of the scraper 131A. Alternatively, as shown in FIG. 2, it is conceivable to place it close to the liquid reservoir or to immerse it therein. Alternatively, the developer flowing out from the opening 20a may be guided to the liquid reservoir via an appropriate guided member.

By setting the opening 20a in this way, the generation of bubbles due to droplets etc. when flowing into the liquid reservoir is reduced as much as possible.

Moreover, many of the bubbles that still occur in the liquid reservoir disappear naturally over the course of the residence time in the liquid reservoir until they are pumped up by the developing roller.

Even so, the remaining bubbles are crushed and disappear during the process in which the developer is conveyed toward the photoreceptor drum while being pumped up in the form of a liquid film onto the developing roller as the developing roller rotates. Thus, one of the objects of the present invention has been achieved.

Next, in the present invention, since the developer having once formed a reservoir is sequentially supplied to the photoreceptor drum via the developing roller, once the reservoir is formed, the scraper and the developing roller Imbalance of the developer in the facing area due to the above problem does not pose much of a problem, and the developer is uniformly supplied via the developing roller. Accordingly, the remaining objects of the invention are also achieved. That is, as described in the prior art, the problem of imbalance in the amount of developer supplied to the photoconductor caused by the phenomenon that the amount of liquid is large only near the nozzle opening and decreases as the distance from the opening is solved is solved. Ru.

However, since it is preferable that the imbalance in the amount of liquid in the liquid reservoir in the longitudinal direction be as small as possible, the nozzle opening 20a is located at the center in the longitudinal direction of the first developing roller 131, as shown in FIG.

In this way, one liquid supply nozzle 20 can sufficiently supply the liquid, but if several liquid supply nozzles are set, the central part of the first developing roller 131 in the axial longitudinal direction may be set. In order to form a more uniform liquid reservoir, it is preferable to arrange the nozzle at a symmetrical position and set the nozzle so that it is tilted toward the center.

In this way, the developer supplied to the photosensitive drum 10 via the first developing roller 131 is transferred to the first developing roller 131.
1 and the photoreceptor drum 10, and gradually transfers onto the photoreceptor as the photoreceptor drum 10 rotates, passes through the second developing roller 132, which has an auxiliary developer supply function, to the squeeze roller 133 and the scraper 133A. The toner is removed from the photoreceptor and collected into the tank 22 through the collection pipe 21 that opens at the bottom of the developer container 130. By the way,
The developer is supplied to the liquid supply nozzle 20 via a supply pipe 23 by the action of a pump P installed in a tank 22.

In addition to the above, the discharge pipe from the pump P is also connected to a developer concentration sensor 24 and a stirring nozzle 25.

Both longitudinal ends of the scrapers 131A and 132A are open, and the liquid flows down from the reservoir. In other words, the developer flowing down from the scraper 131A is
You can take it at 2A. The developer flowing down from the scraper 132A is received by the developer container 130.

Each scraper 131A, 132A is slightly longer than the axial length of each developing roller so that it also functions as a cleaning member. For example, both ends are made to protrude outward from the developing roller by about 1 to 2 mm.

In the present invention, it is necessary that a liquid reservoir is always formed in the area where the developing roller and the scraper face each other. The developing roller is formed over the longitudinal direction of the developing roller to such an extent that unevenness such as liquid shortage or uneven development does not occur at least in the area where the electrostatic latent image exists on the photoreceptor when the electrostatic latent image is present. It is necessary to be present.

For this reason, the amount of developer supplied by the liquid supply nozzle is determined by taking into consideration the rotational speed of the developing roller and the viscosity of the developer, which are related to the amount pumped up by the developing roller.

It is assumed that a so-called developing bias is applied to the developing roller at least during the developing process to prevent background staining.

In the experimental example, a Mylarai film with a thickness of about 250 μm was used as the scrapers 131A and 132A, and the roller diameter of both the 1st and 2nd image rollers 131 and 132 was 22 m + m.
is driven at a circumferential speed of 200 to 300 am/sec, and a developer having a viscosity of 1.0 to 1.7 cp is supplied from the liquid supply nozzle 20 to 1.
Carry out at a supply rate of 2oO ~ 1500m Q / polishing,
A suitable amount of liquid reservoir was formed in the longitudinal direction of the axis of the developing roller 131 to obtain good development results.

(Effects) In this way, in the present invention, the developer is stored between the developing roller and the scraper, and then the developer is transferred to the photoreceptor drum side by the developing roller, so that air bubbles disappear. In addition, since the developer between the photoreceptor and the developing roller forms a uniform reservoir, it is convenient to easily obtain uniform image quality without uneven image density or blurred images.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of the main parts of a transfer type electrophotographic copying machine to which the present invention is applied, FIG. A perspective view of the area around the image roller,
Figure 4 is a front view of the developing device section explaining the prior art;
The figure is a perspective view illustrating the main parts of the same figure. 10...Photosensitive drum, 20...Liquid supply nozzle, 131...First developing roller, 131A...Scraper. Engraving of drawings (no changes in content) FIG, 1 FIG. 2 F I G, 4 F I G, 5 Procedural amendment (September 30, 1985 1, Indication of case 1985 Patent Application No. 129476 2, Title of invention Developing solution supply device 3, Amendment Relationship to the patent applicant's case Name of patent applicant (674) Ricoh Co., Ltd. 4, Agent
Address: 4-5-4-7 Kyodo, Setagaya-ku, Tokyo Contents of amendment

Claims (1)

[Scope of Claims] In a wet development method in which a developer is supplied to the surface of a latent image carrier carrying an electrostatic latent image to visualize the electrostatic latent image, a developing roller is applied to the latent image carrier. The scraper is placed close to the developing roller, and the scraper is brought into pressure contact with the developing roller so that it can collect liquid.
The developer supply is characterized in that the developer is temporarily stored in an area facing the developing roller and the scraper, and the stored developer is drawn up in the form of a liquid film as the developing roller rotates and is supplied to the latent image carrier. Device.