JP2656367B2 - Wet electrophotographic development method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Industrial Application Field) The present invention provides a useful developer replenishment suitable for an improved structure of a developing section when wet developing an electrophotographic photosensitive material. The present invention relates to a wet electrophotographic development method.

(Prior Art) FIG. 2 is a sectional structural view schematically showing a conventional camera type electrophotographic plate making machine 2A.
The photographic light emitted from a light source (not shown) to the original 28 held in the camera is reflected by the surface of the original 28, reflected by the upper mirror 21, and collected by the lens 22. The condensed photographing light is supplied from the sheet feeding unit 23 by a transport unit, and is supplied to the photographing unit 29.
An image is formed on an electrophotographic photosensitive material (hereinafter, simply referred to as a master) P held by the image forming apparatus. The photographed master P is conveyed to the developing unit 24 by the conveying unit and developed, fixed in the fixing unit 25, hydrophilized in the etching unit 26, and then dried and released from the outlet 27. I have.

Developing section of such a camera type electrophotographic plate making machine 2A
A general wet electrophotographic developing device used for 24,
The essential points of the developing principle will be described below.

FIG. 3 is a sectional structural view showing an outline of a "single-jet type" wet electrophotographic developing apparatus 1A which is generally widely used because of its simple structure, low cost and easy maintenance. A main electrode 10 and an auxiliary electrode 11, each of which is composed of two electric conductors (hereinafter referred to as electrodes) to which the same potential or a bias potential is applied.
Between the master 10 and the master P, there is provided a developing solution discharging means 12 for discharging the developing solution DL. A thread-like guide 13 made of nylon or the like is provided on the auxiliary electrode 11 to improve the passage of the master P and prevent toner particles from adhering to the back of the master P. A squeezing roller 15 for squeezing and removing the surplus developer is provided.

In such a configuration, when the master P is conveyed on the thread guide 13 via the feed roller 14 with its photosensitive surface (image surface) facing upward, the developer P discharged from the developer discharging means 12 The charged toner particles adhere to the image portion of the master P by a predetermined amount according to the electric field strength between the main electrode 10 and the master P, thereby performing the development.

(Problems to be Solved by the Invention) As described above, since the developing unit 24 of the conventional electrophotographic plate making machine 2A is an open type, the solvent in the developer DL is easily evaporated. The evaporated developer was replenished with the replenishing developer, but in the past, the replenishment amount was large and the toner film was easily formed.
There have been problems in that maintenance work has to be performed frequently and cleaning at that time is difficult. by the way,
In the replenishment using the replenishing developer, a method of replenishing the same component as that of the mother liquor (feeding solution) by a reduced amount, and a method of preparing two types having a solid content higher or lower than the mother liquor and replenishing the required amount are provided. There is a way. However, in the former case, when the image area of the document is excessively large, the toner particles decrease rapidly, causing a decrease in the toner image density, causing problems such as poor printing durability. In the latter case, three types of developer must be prepared, which is a factor of cost increase for both the developer maker and the user.

SUMMARY OF THE INVENTION The present invention has been made under the circumstances described above, and an object of the present invention is to reduce the cost of the developer and the developer on the user side and the manufacturer side, and to obtain a sufficient toner image density for a long period of time. It is an object of the present invention to provide a wet electrophotographic developing method which can be used stably throughout.

SUMMARY OF THE INVENTION (Means for Solving the Problems) The present invention relates to a wet electrophotographic developing method for performing a useful replenishment of a developing solution adapted to an improved structure of a developing unit when wet developing an electrophotographic photosensitive material. An object of the present invention is to provide a replenishing developer having a hermetically sealed structure in which all parts and parts that are wet with a toner constituting a developing unit for performing wet development of an electrophotographic photosensitive material are arranged inside a seal space. This can be achieved by preparing a liquid having the same concentration as the liquid to be supplied and a liquid having a higher concentration than the liquid to be supplied, and adjusting the replenishment amounts of both according to the image area of the document or the number of sheets to be processed.

(Function) In the present invention, since the developing portion for wet developing the electrophotographic photosensitive material has a closed structure, the amount of evaporation of the solvent is reduced, so it is necessary to prepare a replenisher having a concentration lower than that of the input solution. Absent. Further, by using a replenisher having a concentration higher than that of the input solution in accordance with the image area of the document, the toner image density does not decrease.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a sectional structural view of a developing section for explaining a wet electrophotographic developing method of the present invention. As shown in FIG. 1, in the present invention, the developing unit 24 (main electrode 10, auxiliary electrode 11, developing solution discharging means 12, thread guide 13, squeezing roller 15, etc. (A part which is wet with, parts)) is sealed with a closed container 16. Next, the replenishment with the replenishing developer in such a sealed structure will be described. Therefore, first, the first input solution is a predetermined amount (for example, 4) of the same developer as the conventional one.
throw into. Next, the replenishing developer is a mother liquor (the same as the input liquid) and a conc.
2 types are prepared. Basically, an image of an ordinary document having an image area of 3 to 5% is dealt with by replenishment of mother liquor, and a case of developing an original having a larger development area is dealt with by replenishment of conch solution. That is, since the amount of evaporation of the solvent is reduced due to the closed structure of the developing unit, it can be dealt with only by replenishment of the mother liquor in the case of a normal document, and the rate of reduction of the toner particles is large in the case of a document having a large image area. Therefore, replenish the solution with conc. In addition, the mother liquor is replenished while maintaining a constant liquid level by, for example, a chicken feeder. The same can be done with a level meter and a pump or other means. Concentrate replenishment is performed by replenishing the required amount with a constant amount pump 17 (variable supply amount) based on the results of density detection or document area measurement, etc., and for each fixed number of sheets.

Here, for example, as a result of performing plate making of 10,000 plates using a manuscript having an image area of 4% while replenishing 0.5 ml of a 3 times concentration replenisher per plate of B4 size master paper, the printing durability was 10,000 sheets. A printing plate with good image quality was obtained. However, when a plate of 6,000 plates was made using an original having an image area of 8%, the printing durability was 3
It was a thousand. In addition, as a result of replenishing 1 ml of a 3x concentration of replenisher per 1 plate of B4 size master paper and using a document with an image area of 8% to make 10,000 plates, the printing durability was 10,000 sheets. Printing plate was obtained.

When it is desired to reduce the replenishment amount of the conch replenisher, the amount is supplemented with the mother liquor. Also, take out the amount of liquid (squeeze roller 15
The change in the amount of stop in response to the change in the image area of the original as well as the difference in the type of the master paper and the roughness of the surface thereof. Further, even when the closed structure is employed as described above, the solvent evaporates slightly, and the amount of evaporation differs between when the surrounding environment is at a low temperature and when the surrounding environment is at a high temperature. As means for dealing with this, the replenishment amount of the conc solution is set based on the liquid usage amount at low temperature (liquid removal amount + evaporation amount). With this setting, when the amount of evaporation increases, the amount of mother liquor replenishment increases accordingly, preventing the developer in use from rapidly concentrating and increasing the so-called fog, thereby preventing contamination. it can.

As described above, by changing the replenishment amount of the high-concentration replenisher in accordance with the image area of the document, development is stabilized for a long time.

Effects of the Invention As described above, according to the wet electrophotographic development method of the present invention, by evaporating the solvent in the developing solution by making the developing section a closed structure, the replenishing amount of the replenishing solution can be reduced. At the same time, a toner film is hardly formed. It is only necessary to prepare two kinds of replenishers, a mother liquor (feed solution) and a conch solution (having a predetermined concentration higher than that of the feed solution). A wide range of documents can be flexibly dealt with, and the cost for both the user and the maker can be minimized. Further, the replenishment amount of the conch replenisher is calculated as (liquid take-out amount +
By setting the used amount of the developer (evaporation amount) as a reference, it is possible to prevent the developer from being stained.

[Brief description of the drawings]

FIG. 1 is a sectional structural view of a developing section for explaining a wet electrophotographic developing method of the present invention, FIG. 2 is a sectional structural view schematically showing a general camera type electrophotographic plate making machine, and FIG. FIG. 1 is a cross-sectional structural view illustrating an outline of a general wet-type electrophotographic developing device. 24: developing unit, 1A: wet electrophotographic developing device, 16: closed container, 10: main electrode, 11: auxiliary electrode, 12: developing solution discharging means, 13: thread guide, 14 ... Feed roller, 15…
… Aperture roller, 17 …… pump, P …… master, 2A ……
Electrophotographic plate making machine.

Claims (3)

(57) [Claims] 1. A hermetically sealed structure in which all parts and parts of a developing unit for wet developing an electrophotographic photosensitive material which are wetted with toner are disposed inside a sealing space, and a replenishing developer having the same concentration as a charging solution is used. And a replenisher having a concentration higher than that of the input solution is prepared, and the replenishment of the replenisher is adjusted according to the image area of the document or the number of sheets to be processed. 2. In the case of a normal document having an image area equal to or less than a predetermined value, only the same density is replenished, and in the case of a document having an image area of a predetermined size or more, the high density is replenished. The wet electrophotographic development method according to claim 1. 3. A replenishment amount of a conch replenisher is set based on (amount of liquid taken out + amount of evaporation) when an amount of evaporation of a developer per unit time is small. 2. The wet electrophotographic development method according to claim 1, wherein the method is used in combination.