JPS58184979A - Electrophotographic copying machine - Google Patents

Abstract

PURPOSE:To prevent the disturbance of a toner image due to a removed carrier, by arranging a magnetic attracting means between a development part and a transfer part to remove the magnetic carrier which is stuck to the surface of the latent image of a photoreceptor together with a toner and transferring the toner well in the transfer process. CONSTITUTION:A magnet 10 as the magnetic attracting means is arranged between a developing device 4 and a corona discharger 5 for transfer so as to face oppositely to a photoreceptor 1. This magnet 10 is provided so as to face oppositely to the overall width of the photoreceptor in the axial direction of the photoreceptor 1. When a toner image part stuck to the latent image of the photoreceptor 1 faces the magnet 10, the carrier is attracted together with the toner to the magnet 10, and they are removed from the toner image part. That is, though the toner as well as the carrier may be stuck to the electrostatic latent image part simultaneously in the developing part, the stuck carrier receives the magnetic attraction and is attracted to the magnet 10 when it faces the magnet 10. At this time, the toner does not receive the action of the magnetic attraction and is not attracted to the magnet 10 because it is not a magnetic material. Thus, the image is transferred well without omission of image.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrophotographic copying machine, particularly an electrophotographic copying machine in which an electrostatic latent image formed on a photoconductor is visualized using a developer from toner and a magnetic carrier. The present invention relates to an electrophotographic copying machine that can effectively transfer images onto paper.

In an electrophotographic copying machine, the surface of a photoreceptor including a photoconductive layer is first uniformly charged to a specific polarity. By exposing the surface of the charged photoreceptor to light in the area of the original, an electrostatic latent image corresponding to the image area of the original is formed. The electrostatic latent image thus formed is visualized in the developing section by adhering colored pigment toner, and this toner image is transferred onto a sheet of paper that is sent as appropriate, for example, by the action of a corona discharge device for transfer. Ru.

The toner image transferred onto the paper is fixed on the paper as the paper is conveyed through the fixing section. The above is the general copying process using electrophotography.

In the developing section of the above electrophotographic copying machine, in order to impart a charge to the toner with a polarity opposite to that of the electrostatic latent image,
A developer consisting of magnetic iron powder called a carrier and toner is used. In other words, the toner is charged to a polarity opposite to that of the electrostatic latent image using frictional charging between the toner and the carrier. Here, when the above-mentioned developer is used, not only toner but also carrier may be attached to the electrostatic latent image.

If this carrier adheres, the toner will not be properly transferred to the paper during the transfer process, resulting in image dropouts (white spots), etc.In other words, the area facing the carrier will appear white.The reason for this is that the carrier When the diameter is compared to the donor diameter, the suction force of the toner onto the paper by the action of the corona discharge device is insufficient, and toner transfer is not performed. and,
Since the carrier is generally a conductor, a possible reason for this is that the charge on the paper caused by the corona discharge device escapes through the carrier, causing no toner attraction force and no toner transfer.

The present invention overcomes the above-mentioned drawbacks and solves one problem in the transfer process.

In order to transfer toner well, the present invention provides the following advantages:
This electrophotographic copying machine is characterized in that it removes the chips and shears that adhere to the toner before the transfer process.

The electrophotographic copying machine of the present invention will be explained in detail below with reference to the drawings.

1- is a diagram schematically showing the copying process in the electrophotographic copying machine of the present invention. In the figure, 1 is a drum-shaped photoreceptor that rotates in the direction of the arrow; 2 is a corona discharger that uniformly charges the surface of the photoreceptor to a specific polarity; and 3 is a photoreceptor that charges the image of the original through an optical system (not shown). 4 is the photoreceptor 1
A developing device 5 visualizes the electrostatic latent image formed on the toner image as a toner image;
A corona discharger 9 transfers the toner image onto the paper 8 guided along the photoreceptor 1.
0, which is a separation roller that separates the parts and transports them to the next fixing section.
After the transfer process, the photoreceptor 1 undergoes a static elimination and cleaning process, and is ready for the next image formation. ::゛The developing device 4 also rotates a developing roll 41, and magnetically attracts iron powder, which is the magnetic carrier 7, onto the surface of the developing roll 410. A large amount of toner is attached to this carrier due to frictional charging or the like, and as the developing roll 41 rotates, the carrier is conveyed to a developing area facing the photoreceptor 1 on which an electrostatic latent image is formed. As a result, the toner is attracted to the electrostatic latent image by the action of electrostatic attraction, and a toner image is formed.

In the present invention, the developing device 4 is configured as described above.
A magnet 10, which is a magnetic attraction means, is arranged between the photoreceptor 1 and the transfer corona discharger 5, facing the photoreceptor 1. This magnet 10Fi is provided facing the entire width of the photoreceptor 1 along the axial direction of the photoreceptor 1.

By providing the magnet 1°0 as described above, when the toner image portion attached to the latent image on the photoconductor 1 faces the magnet 10, the carrier is attracted to the magnet 10 along with the toner, and is removed from the toner image portion. It will be done. In other words, carrier may adhere to the electrostatic latent image area together with toner in the developing section. If this attached carrier faces the magnet 10, it will receive the magnetic attraction force from the magnet 10.
I'm on the side. At this time, since the toner is not a magnetic substance, it is not affected by the magnetic attraction force and is not attracted to the magnet 10. In this way, after the carrier attached with the toner is removed by the magnet 10, the toner image on the photoreceptor 1 is transferred to the paper 8 facing the corona discharger 5 and sent as appropriate, without any image omission. transcribed.

The distance between the magnet 10 and the photoreceptor 1 is sufficient as long as it can attract carriers; if the magnet 10 is placed too close to the photoreceptor 1, there is a risk that the attracted carriers will accumulate and come into contact with the photoreceptor 1, disturbing the toner image. There is.

FIG. 2 is a diagram showing another embodiment of the magnetic attraction means of the present invention. In the figure, the magnetic adsorption means 11 forms a reservoir 12 for storing the adsorbed carriers. That is, the magnetic adsorption means 11 has magnetic pieces 13 and 14 fixed to each magnetic pole of the magnet 10', and a carrier reservoir 12 is formed between the magnetic pieces 13 and 14. Magnetic piece 13.
Each of the 14 carriers 15 is attracted mainly at the tips of the magnetic pieces 13 and 14, and is gradually accumulated in the reservoir 12 by the magnetic force acting between the magnetic pieces 13 and 14.

In particular, most of the carriers are attracted to the tip of the magnetic piece 13, and the contact with the photoreceptor 1 gives a force to move it to the reservoir 12, and the magnetic force acting between the magnetic pieces 13 and 14 is combined with the , carriers 12 are accumulated in the reservoir 12.

As explained above, according to the electrophotographic copying machine of the present invention, since the magnetic adsorption means is disposed between the developing section and the transfer section, the magnetic carrier attached to the latent image surface of the photoreceptor along with the toner is removed. Therefore, the toner can be transferred well in the transfer process.

In addition, by configuring the magnetic adsorption means to form a reservoir with a magnet and a magnetic material, it is possible to accumulate the removed carrier in the reservoir, and the removed carrier 1.1: rear toner image is not disturbed. can be prevented.

[Brief explanation of drawings]

FIG. 11 is a diagram showing an outline of the copying process of the electrophotographic copying machine according to the present invention, and FIG. 2 is a side view showing an embodiment of the magnetic attraction means according to the present invention. 01; Photoreceptor 2; Corona discharger 3 : Exposure section 4; Developing device 41; Developing roll 5; Corona discharger (for transfer) 8; Paper 10 (1
0'); Magne 7) 11; Magnetic adsorption means 12; Reservoir 13.14; Magnetic piece 15; Carrier agent, patent attorney Aihiko Fukushi (and 2 others): 11°

Claims (1)

[Claims] 1. An electrostatic latent image is formed on a photoreceptor by a charging and exposing means, and the electrostatic latent image is visualized as a toner image by a developing means using a developer consisting of a carrier and toner. In an electrophotographic copying machine that later transfers the toner image onto paper, an adsorption means for magnetically attracting the magnetic carrier adhering to the photoreceptor is provided on the photoreceptor between the development means and the toner image transfer process. An electrophotographic copying machine characterized by being arranged facing each other. 2. The electrophotographic copying machine according to claim 1, wherein the attraction means is constructed by combining a magnet and a magnetic member.