JPS6335982B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a corona discharger for electrophotographic processes.

2. Description of the Related Art An electrophotographic process in which an electrostatic latent image is formed on a latent image carrier and this electrostatic latent image is developed is well known.

For example, FIG. 1 shows a typical example of a copying apparatus to which such an electrophotographic process is applied.

The drum-shaped photoconductive photoreceptor 1 is rotatable in the direction of the arrow. During copying, it rotates in the direction of the arrow, and after being neutralized by the first static eliminator 8, it is charged by the charger 2 and this charging is performed. An electrostatic latent image is formed by image exposure using a light image of the document.

This electrostatic latent image is transferred to a developing section, that is, a developing device 3.
A developing solution is supplied to a portion where the developing electrode 31 and the photoreceptor 1 are closely opposed to each other, and wet development is performed.

When the excess developer on the photoreceptor 1 is removed by the squeeze roller 32 and the scraper 33, the visible image is transferred onto the recording sheet S by the transfer charger 4.

After the visible image has been transferred, the photoreceptor 1 is neutralized by a second static eliminator 5, and residual toner is further removed by a cleaning roll 6 and a cleaning blade 7.

Wet-type electrophotographic processes are not limited to these processes, but include those using a so-called static image transfer method, and those in which the latent image carrier itself is in the form of a sheet, and the formed electrostatic latent image is transferred onto the latent image carrier. There is a so-called EF method in which the image is visualized and directly recorded, but the present invention is applicable not only to all of these wet electrophotographic processes but also to dry electrophotographic processes. Furthermore, in this specification, when referring to a corona discharger for an electrophotographic process, it refers not only to a corona discharger used for simply charging a latent image carrier, but also to approximately all corona dischargers used for carrying out an electrophotographic process. shall be designated. Therefore, in the example of the apparatus shown in FIG. 1, not only the charger 2 but also the first static eliminator 8, transfer charger 4, and second static eliminator 5 are corona dischargers for electrophotographic processes. Furthermore, a so-called multi-stylus may also be used as a corona discharger for electrophotographic processes.

Corona dischargers for electrophotographic processes are generally
It is composed of a charge wire stretched in a certain direction and an outer surrounding member that partially surrounds the charge wire along the longitudinal direction. Specifically, corotron type and scorotron type are known. Anything that has a charge wire and is used for electrophotographic processes is a corona discharger for electrophotographic processes. Note that in the case of the multi-stylus described above, each needle electrode or charge wire is used.

Now, when wet development is performed, developer mist is inevitably generated within the electrophotographic apparatus.
This developer mist floats within the device and adheres to various equipment. When the mist adheres and a long period of time passes, the dispersion medium evaporates, and the dispersed toner sticks to the area where the mist adheres. This kind of toner sticking occurs in all parts of the device,
Charge wire is no exception to this.

In other words, if you look at the charge wire of a charger that has been used for a long time in a wet electrophotographic device, the second
As shown in the figure, it can be seen that the toner T is stuck to the charge wire W.

In this way, the toner T stuck to the charge wire W causes a decline in the discharge function of the corona discharger, resulting in various inconveniences including a decline in the quality of recorded images.

In order to prevent this, conventionally, it has been necessary to periodically clean the charge wire.

In view of the above, an object of the present invention is to provide a corona discharger for an electrophotographic process that can effectively prevent toner from adhering to a charge wire.

The present invention will be explained below.

A feature of the present invention is that at least the charge wire of the corona discharger for electrophotographic process is coated with an oil repellent. In carrying out the present invention, it is only necessary to apply an oil repellent to at least the charge wire. Therefore, all conventional chargers can be used without any modification to the charger body. No need to add.
In the case of a multi-stylus, applying an oil repellent to the charge wire means applying an oil repellent to the end face of the stylus.

Specific examples of oil repellents include tetrafluoroethylene, trifluoroethylene, vinylidene fluoride, tetrafluoroethylene-hexafluoropropylene copolymer,
Examples include IH-pentadecafluorooctyl methacrylate, perfluorinated alcohol, perfluoroalkyl ester polymer, perfluorinated lauric acid, vinyl chloride, and fluorine-containing hydroxy unsaturated ester.

Applying these oil repellents to the charge wire means forming a layer of these oil repellents several micrometers thick on the charge wire. Experiments have shown that the application of oil repellent has no effect on the discharge function of the corona discharger.

For applying the oil repellent, an appropriate method may be selected depending on the type of oil repellent. For example, in the case of IH-pentadecafluorooctyl methacrylate, it is only necessary to dilute it with a volatile solvent and spray it on. In this case, a coating layer is formed as the diluting solvent evaporates.

These oil repellents repel the dispersion medium of the developer, so the charge wire coated with the oil repellent has
Developer mist is difficult to adhere to, and even if it does, its adhesion is extremely weak.

It is known that charge wires vibrate minutely during discharge. This micro-vibration serves to screen out mist adhering to the charge wire. For this reason, the charge wire of the corona discharger according to the invention has no or very little toner adhesion. Therefore,
With the corona discharger of the present invention, cleaning of the charge wire is not necessary at all, or only rarely.

Specific examples will be given below.

In the copying machine shown in FIG. 1, the charger of the present invention was used for the charger 2, the transfer charger 4, the first static eliminator 8, and the second static eliminator 8. The aforementioned IH-pentadecafluorooctyl methacrylate was used as the oil repellent.

100,000 copies were made intermittently using the apparatus shown in FIG. 1, and the charge wire of each corona discharger was inspected for dirt, that is, the degree of toner adhesion, using a magnifying glass. As a result, it was found that there was no toner sticking to the charge wires of the charger 2, transfer charger 4, and first static eliminator 8. In other words, it can be said that toner sticking has been completely solved in these corona dischargers.

A very small amount of toner was observed to adhere to the charge wire of the first static eliminator 5. In particular, the first static eliminator 5 is removed by the cleaning roll 6.
This is thought to be because a large amount of developer mist is generated near the . Note that this stain could be easily removed by wiping the charge wire with a cloth impregnated with ethyl alcohol. However, since the oil repellent is generally easily removed by friction, when cleaning the charge wire in this way, it is necessary to reapply the oil repellent after cleaning.

On the other hand, when similar experiments were conducted using conventional corona dischargers, it was found that the adhesion and solidification of toner in each corona discharger was remarkable, especially for the charge wire of the second static eliminator. The solidified toner could not be removed just by rubbing it with a cloth, but could only be removed by rubbing it vigorously with a cloth soaked in toluene.

By the way, the various oil repellents mentioned above have both oil repellency and water repellency. It has been found that because of the water-repellent nature of the oil repellent, the corona discharger of the present invention has yet another unique effect.

In recent years, so-called humidifiers have become popular in order to cope with abnormal dryness in winter, and humidifiers are often used in places where copying machines are installed. There are various types of humidifiers, but some use ultrasonic vibrations to create steam. When a copying machine is used in a room where a humidifier of this type is used, water scale-like substances that adhere to iron bottles and the like will be deposited on the charge wire of the corona discharger. Needless to say, this adversely affects the discharge function of the corona discharger.

This water scale-like adhesion is due to the ionization of fine water particles emitted from the microscope, which makes it easy for the fine particles to adhere to the charge wire. This is thought to be due to calcium and other substances adhering to the charge wire.

However, in the case of the corona discharger of the present invention, it was found that the above-mentioned scale-like deposits were not formed at all.
This is because water particles from the humidifier no longer adhere to the charge wire due to the water repellency of the oil repellent and the minute vibrations of the charge wire. From this point of view, applying an oil repellent to the charge wire also has meaning for chargers for dry electrophotographic processes.

[Brief explanation of the drawing]

Figure 1 shows one of the devices that performs the electrophotographic process.
FIG. 2 is a front view illustratively showing essential parts of an exemplary copying machine, and is an explanatory diagram for explaining the adhesion of toner to a charge wire. 1... Photoreceptor, 2... Charger, 4... Transfer charger, 5... Second static eliminator, 8... First
Static eliminator.

Claims (1)

[Claims] 1. A corona discharger for an electrophotographic process, characterized in that at least a charge wire is coated with an oil repellent.