JPH0293572A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent the lowering of copy quality by maintaining a stable electric discharging characteristic by adhering developer to non image part of an image carrier and stopping one operation of transferring, separating, or cleaning related means while it is passed through. CONSTITUTION:When the developer, which is adhered to the non image part of a photosensitive body 1, is passed through electrifying devices which face the photosensitive drum 1 to be utilized for image forming for transferring 7, separating 8, and before cleaning 10, etc., the electrical discharging of the electrifying device and/or operation of an exhausting fan for atomosphere inside the electrifying device are/is temporarily stopped. Thus soiling by toner of the inside of the electrifying devices 2, 5, 7, 8, 10, and an electrical discharging wire can be prevented, stability of the electric discharging characteristic of each electrifying device can be maintained over a long period of time, the separating failure of the transferring paper and generation of retransferring to the transferring paper by splashing toner can be prevented, and the lowering of the copy quality can be prevented.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an electrophotographic copying machine using a dry developer;
The present invention relates to image forming apparatuses such as printers and facsimile machines, and particularly relates to image forming apparatuses having means for solving problems when developer adheres to non-image areas of an image carrier.

(Prior Art) In an image forming apparatus such as an electrophotographic apparatus, a toner image formed on the surface of an electrophotographic photoreceptor is transferred to a transfer material such as paper to obtain a copy. After removing toner and the like remaining on the surface using various types of cleaning means, the toner (described below) is repeatedly subjected to an image forming process.

As an example of this type of cleaning means, a configuration using a cleaning blade made of an elastic material such as urethane or rubber is common, and such a configuration is simple, small and compact, and has an excellent ability to remove residual toner. Because of this, it has been widely used in practice.

However, although this type of leaning blade has an excellent toner removal function, it is not effective in removing precipitates such as rosin generated from transfer paper, or discharge products such as ozone generated from high voltage components in the device. If a large amount of such a substance adheres to the surface of the photoreceptor, image blurring may occur under high humidity, resulting in a deterioration in the quality of the copied image.

In this case, in order to remove the deposits on the photoreceptor, an elastic roller is installed as a cleaning means to strongly rub the surface of the photoreceptor, or a magnetic roller is installed and a magnetic particle layer is formed on the roller. A structure in which the magnetic particles are rubbed against the surface of a photoreceptor to remove the deposits has been proposed and is actually used.

Additionally, in order to prevent discharge products from the charger from accumulating inside the charger or near the surface of the photoreceptor, an opening is provided in the charger and the atmosphere inside the charger is forcibly exhausted using fan means. There is.

On the other hand, in recent years, it has become desirable to identify copy images by color using two-color or multi-color developers, and toners of colors other than black have come to be used more frequently. Generally, toners of colors other than black are currently mainly non-magnetic toners, which are more likely to scatter than magnetic toners and pollute the interior of the machine. Also,
Unlike magnetic toner, the resin does not contain magnetite, and the abrasive force is weaker than that of conventional magnetic toner.
As a result, the particles tend to collect and adhere to the photoreceptor, causing poor cleaning, resulting in problems such as deterioration in the quality of copied images.

In addition, in the cleaning means described above, which uses a magnetic roller to form a magnetic particle layer using a magnetic toner layer and rubs the surface of the photoreceptor, if copies made only of color toner continue, the magnetic particles The surface of the layer was covered with colored toner, and this colored toner sometimes flew into the machine, causing toner contamination.

In order to prevent cleaning failures caused by non-magnetic toner, fusion of non-magnetic toner, and scattering within the machine, when non-magnetic color toner is used in the color development process, magnetic toner is not developed. The inventors of the present application have already proposed a method in which magnetic toner is attached to a non-image area of the surface of a photoreceptor set in a direction perpendicular to the eight directions of the photoreceptor using a black developing device, and the toner is supplied to a cleaning means. has been done.

In the above example, a two-color or multicolor copying machine that uses magnetic toner and non-magnetic toner was explained. It has been proposed in the past to attach a developer to the above-mentioned non-image area for the purpose of maintaining the balance of external additives in the developer.

[Problem that the invention seeks to solve] However,
In the above conventional example, the transfer/separation means, etc. were operated in the same way as during normal copying, so the toner inside the charger was heavily contaminated, causing problems in maintaining stable discharge characteristics over a long period of time, and causing problems in the transfer paper. Poor separation or contaminated toner inside the machine may cause the transfer to adhere to the transfer paper and stain the transfer paper.
Copy quality could be degraded.

[Means for Solving the Problems] According to the present invention, when developer is attached to the non-image area on the surface of the photoreceptor, when the attached developer passes through each charger section, the charger Stop suction operations such as discharge and ozone removal fans.

This prevents contamination of the charger and the discharge wire toner, and maintains the stability of the discharge characteristics of each charger over a long period of time.
This makes it possible to prevent poor separation of the transfer paper and re-transfer to the transfer paper due to scattered toner, thereby preventing deterioration in copy quality.

[Example] FIG. 2 is a schematic diagram of a two-color copying machine embodying the present invention.

In the figure, reference numeral 1 denotes an electrophotographic photoreceptor, which rotates in the direction of the arrow, is uniformly charged by a main charger 2, and a latent image is formed on the photoreceptor by image exposure 3. In the case of a color copy, the latent image is red,
The image is developed by a developing device 4a using non-magnetic toner such as blue, and in the case of a black copy, it is developed by a block imager 4b using black magnetic toner. The pre-transfer charger 5 applies charges of the same polarity as the toner to the toner forming the toner image. The transfer paper is conveyed by a paper feed system 6, and the toner image is transferred onto the transfer material by a transfer charger 7 which applies an electric charge of opposite polarity to the toner to the back surface of the transfer material, and is separated from the photoreceptor by a separation charger 8. 9 to a fixing means (not shown) to complete a series of copying processes.

On the other hand, the photoreceptor is cleaned by a cleaning means 11 using a well-known blade plate, and is brought to a uniform potential by pre-exposure 12 to remove residual charges before proceeding to the next step.

Incidentally, FIG. 5 shows a schematic diagram of the cleaner.

Next, FIG. 1(a) is a timing chart diagram showing a first embodiment of the present invention. This figure shows a sequence in which black (IFL) toner is developed on the photoconductor during the subsequent rotation of the photoconductor after copying one sheet using color (non-magnetic) toner.

At the time of post-rotation, the pre-transfer charger and the fan installed in the pre-transfer charger, which give a charge of the same polarity as the black toner, remain ONL, and the other chargers and the fans associated with those chargers remain 0FFt. It is. Turn on the pre-transfer charger here.
The reason for this was to strengthen the charge of the toner, increase its adhesion to the photoreceptor, and prevent it from scattering.These were kept in the ON state in order to exhaust the atmosphere containing discharge products.

Immediately after the fan of the transfer/separation charger is turned off, the fan rotates due to inertia, but the suction force itself is weakened, so there was an effect of preventing toner scattering to some extent.

[Other Embodiments] FIG.
This is an example of continuous copying, and is a timing chart for attaching black toner between copying the second and third sheets and during post-rotation. As in the previous embodiment (1), only the pre-transfer charger and its fan remain ONL, and when magnetic toner is attached as described above between the 2nd copy and 3rd copy during transfer copying, Although the fans of the transfer and separation chargers were turned off in the sequence, they actually rotated by inertia as in the first embodiment. However, since the suction force generated by the rotation of the fan was weakened, it was effective to some extent in preventing the charger from becoming contaminated by toner.

Regarding the third embodiment, in general, the pre-transfer charger and the separation charger have a DC component superimposed on high-voltage AC, and the DC component is often of the same polarity between both chargers. They often share high-voltage transformers, etc. Separately charged types are 0FFL.

However, in that case, the sequence of the pre-transfer and separation chargers would be the same as shown in FIG. 1(C).

The fourth embodiment will be described below. In the first to third embodiments described above, a two-color copying machine that uses magnetic toner and non-magnetic toner is described. An embodiment to which the present invention is applied is shown in the timing chart of FIG. 1(d). As in the second embodiment, black toner is applied to the woody layer side between the second and third sheets of four-sheet continuous copying and during post-rotation. Further, since each fan is the same, a detailed explanation is omitted.

In addition, in this case, the purpose is to make the developer components uniform, such as the balance between the toner and external additives in the developing device, and the magnetism of the toner,
Either non-magnetic material is fine.

Several representative examples have been described above for the first to fourth embodiments, but the discharge of the charger and the ON-OFF of the fan of each charger are not limited to those described above, and the fan may not necessarily be used. Various combinations are possible. In short, it is sufficient if the drive control of each charger and/or fan is effective in maintaining the normal operating performance of each charger, etc. so that the chargers are not contaminated.

As for other chargers, if a pre-cleaning charger and a fan for the charger are used, they will be omitted because they are the same as other chargers. It is shown in Figure 3.

A further variant in each case is to deposit magnetic toner. For example, the main charger used for this purpose may be removed and the discharge of all chargers may be turned off.

[Effects of the Invention] As explained above, the present invention can be used to prevent non-magnetic toner from scattering, to maintain the balance of external additives in the developer, and to abrade the deteriorated layer or harmful substance adhering layer of the photoreceptor. If the image forming apparatus is configured to apply developer to the non-image area of the photoreceptor, the attached developer may be used for image formation before transfer separation and cleaning, but it is necessary to face the photoreceptor. By stopping the discharge of the charger or the operation of the fan for exhausting the atmosphere inside the charger at a certain point, for example, the developer of the shield and discharge wire that constitute the charger can be removed. It was possible to prevent stains caused by This made it possible to maintain stable discharge characteristics and prevent transfer failure, retransfer, etc., which was effective in maintaining high quality copy images.

[Brief explanation of drawings]

Figures 1(a) to 1(C) are sequence diagrams of an example using a two-color copying machine, Figure 1(d) is a sequence diagram of an example using a black-and-white copying machine, and Figure 2 is a two-color copying example. Fig. 3 is a schematic diagram of another two-color copying machine, Fig. 4 is a schematic diagram of a black and white copying machine, and Fig. 5 is a schematic diagram of a cleaning device with a magnetic roller used in the example. . In the figure, 1... Image carrier 2... Main charger 3... Image exposure 4... Developing device (4a, 4b) 5... Pre-transfer charger and FAN 6... Paper feed Means 7...Transfer charger and FAN 8...Separation charger and FAN 9...Transporting means 11...Cleaning means 12...Pre-exposure 3...Blank exposure 0...Charging before cleaning and FAN4...Magnet roller 5...Magnetic toner layer 6...Toner layer thickness regulating roller 7...Cleaning blade

Claims (1)

[Claims] 1. An electrostatic latent image is formed on an image carrier, the latent image is developed with a developer, and the developer image is transferred to the transfer material by a transfer means, and remains on the image carrier. In an image forming apparatus that removes developer residue and reuses the image carrier repeatedly, developer is attached to the non-image area of the image carrier, and the attached developer is transferred, separated, and cleaned. An image forming apparatus characterized by stopping operation of at least one of the related means when passing through the related means. 2. The above-mentioned transfer separation means includes a transfer charger, a separation charger,
The image forming apparatus according to claim 1, which is a pre-transfer charger or an exhaust fan for the atmosphere inside the charger. 3. The image forming apparatus according to claim (1), wherein the cleaning-related means is a pre-cleaning charger or an exhaust fan for the atmosphere inside the charger.