JP2001042661A - Transfer method used for electrophotographic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transfer method, capable of effectively preventing the rear surface of a transfer paper from being soiled by toner, simultaneously with effective removing of paper powder from the transfer paper in a method for transferring a toner image to the surface of the transfer paper from the surface of a photoreceptor drum, using a transfer roller. SOLUTION: A transfer roller 5 is arranged to face to the surface of the photoreceptor drum and is held at a potential having a polarity opposite to that of the electrification polarity of a toner, then a guide plate 31 consisting of an insulating member is provided near the roller 5, so that a transfer paper 10 is guided to a gap between the roller 5 and the photoreceptor drum 1 by the plate 31 and made to pass through the gap, whereby the toner image on the surface of the drum 1 is transferred to the surface of the paper 10 in this method. A paper powder removing device 40 consisting of a pair of paper powder scraping rollers and a destaticizing device 50 consisting of a conductive member held at zero potential are arranged on the carrying path of the paper 10, and the paper powder adhering to the paper 10 is removed by making the paper 10 pass through a space between the paper powder scraping rollers. After the paper 10 is brought into contact with the conductive member, by making the paper pass through the gap between the roller 5 and the drum 1 via the plate 31, so that the image is transferred to the paper 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copying machine, a printer,
The present invention relates to a transfer method using a transfer roller used in an electrophotographic apparatus such as a facsimile.

[0002]

2. Description of the Related Art In an electrophotographic apparatus represented by a copying machine, the surface of a photosensitive drum is uniformly charged, and an electrostatic latent image corresponding to a document image is formed on the surface of the photosensitive drum by image exposure. By developing the electrostatic latent image to form a toner image on the surface of the photoconductor drum, transferring the toner image from the surface of the photoconductor drum onto transfer paper, and fixing the transferred toner image by heat, pressure, or the like. , An image is formed.

In such an electrophotographic apparatus, a method using a corona charger (transfer charger) or a transfer roller is widely used as a means for transferring a toner image formed on the surface of a photosensitive drum onto a transfer material. ing. In the method using a corona charger, the back surface of the transfer material is charged to a polarity opposite to that of the toner image by corona discharge, and the toner image is transferred to the surface of the transfer paper by the charged charge. In the method using a transfer roller, a voltage is applied to the roller so that the roller is maintained at a potential having a polarity opposite to that of the toner image. In this state, the transfer paper is transferred between the photosensitive drum and the transfer roller. Then, the toner image is transferred onto the surface of the transfer paper by an electric field formed between the transfer roller and the toner image.

However, in the transfer method using a corona charger, the transfer paper is electrostatically attracted to the surface of the photosensitive drum, so that the transfer material on which the toner image has been transferred is separated from the surface of the photosensitive drum. There is a problem that an AC charger must be used together and the transfer mechanism becomes complicated. Another problem is that ozone is generated by corona charging.
On the other hand, in the transfer method using the transfer roller, the transfer paper can be easily separated from the photosensitive drum surface, and the transfer paper can be separated without using a member such as a corona charger. Further, there is no problem of generation of ozone, and in this respect, the method is superior to the method using the corona charger.

Further, in recent years, a toner recycling method in which a toner image formed on the surface of a photosensitive drum is transferred onto transfer paper, and the remaining toner collected by a cleaning device is recycled to a developing device and reused, Attention has been paid to an electrophotographic method using a cleaner-less method that does not clean the surface of the photosensitive drum, and has come into practical use. In such a toner recycling method and a cleaner-less method, paper dust of transfer paper is particularly problematic. That is, when the paper powder component (talc, kaolin, etc.) adheres to the photosensitive drum,
It causes image abnormalities due to poor charging. Therefore, it is necessary to remove paper dust from the transfer paper prior to the transfer. Removal of the paper dust from the transfer paper is usually performed by passing the transfer paper between a pair of insulating rollers to scrape the paper dust.

[0006]

However, if the paper dust is removed from the transfer paper by the above-described method, the back surface of the transfer paper (the side opposite to the transfer surface) is often stained with toner. That is, when a toner image is transferred by the transfer roller, the transfer paper is smoothly introduced into the gap between the transfer roller and the photosensitive drum and the vicinity of the transfer roller is increased in order to enhance the adhesion between the transfer paper and the photosensitive drum. That is, an insulating guide plate is provided near the photosensitive drum, and toner adheres to this guide plate, and the toner adheres to the back surface of the transfer paper. Probably, such toner adhesion to the guide plate is frictionally charged when the transfer paper comes into contact with the insulating roller for scraping the paper dust, and the charged transfer paper comes into contact with the guide plate, thereby causing friction between the two. The electrification is promoted and the guide plate is electrified, and since the electrified guide plate is located near the surface of the photoreceptor drum, toner having a polarity opposite to the charge polarity of the guide plate gradually adheres to the guide plate.
It is considered that the toner accumulates, and as a result, the toner adheres to the back surface of the transfer sheet when the transfer sheet passes over the guide plate.

Accordingly, an object of the present invention is to provide a method for transferring a toner image from the surface of a photoreceptor drum to the surface of a transfer paper using a transfer roller. An object of the present invention is to provide a transfer method in which toner contamination on the back surface is effectively prevented.

[0008]

According to the present invention, a transfer roller is disposed so as to face the surface of a photoreceptor drum, and the transfer roller is maintained at a potential having a polarity opposite to the charging polarity of the toner. A guide plate made of an insulating member is provided in the vicinity of the roller, and the transfer paper is guided by the guide plate into a gap between the transfer roller and the photosensitive drum, and the transfer paper is passed through the gap, thereby forming a surface of the photosensitive drum. In a method of transferring a toner image formed by developing an electrostatic latent image from the surface of a photosensitive drum to the surface of a transfer sheet, a paper comprising a pair of paper dust scraping rollers on a transfer path of the transfer sheet. A powder removing device and a static eliminator made of a conductive member held at zero potential are arranged, and the transfer paper is removed between the paper dust scraping rollers to remove paper dust attached to the transfer paper,
Next, the transfer paper is brought into contact with the conductive member or passed near the conductive member, and thereafter, the transfer paper passes through the gap between the transfer roller and the photosensitive drum via the guide plate. A transfer method is provided, wherein the transfer is performed.

In general, the transfer method of the present invention is characterized in that a paper dust removing device and a static eliminator are arranged on a transfer path of a transfer sheet prior to transfer. That is, the paper dust removing device includes a pair of paper dust scraping rollers (for example, an insulating roller), and the transfer paper is passed between the rollers, and the paper dust of the transfer paper is removed by frictional contact with the rollers. It is scraped off. In addition, the static eliminator is made of a conductive member whose potential is kept at zero, and the transfer paper from which the paper dust has been scraped off contacts the conductive member or passes near the conductive member. To eliminate the charge. That is, the transfer paper is frictionally charged at the same time as the paper dust is removed due to the frictional contact with the paper dust scraping roller, and the charged charge is removed by the conductive member.

According to the present invention, the transfer paper from which the paper dust has been removed and whose charge has been removed in this way passes between the transfer roller and the surface of the photosensitive drum (hereinafter, may be simply referred to as a transfer area). Then, by performing the transfer known per se, it is possible to prevent the back surface of the transfer paper from being stained. That is, the transfer paper is introduced into the transfer area and transferred while being in contact with the insulating guide plate provided near the transfer roller. However, since the transfer paper has been neutralized, the frictional charge of the guide plate is reduced. As a result, toner does not adhere to and accumulate on the guide plate, and toner stains on the back surface of the transfer paper are effectively prevented.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to specific examples shown in the accompanying drawings. FIG. 1 is a diagram showing an outline of an overall arrangement of an electrophotographic apparatus, and FIG. 2 is a diagram showing an arrangement of a transfer path of a transfer sheet in which the transfer method of the present invention can be suitably performed.

In FIG. 1, in this electrophotographic apparatus, a main charging device 2, an exposure mechanism 3, a developing device 4, a transfer roller are provided around a photosensitive drum 1 rotatably provided in a direction indicated by an arrow in FIG. 5, static eliminator 6, cleaning device 7
Are arranged in this order along the rotation direction of the photoconductor drum 1, and between the photoconductor drum 1 and the transfer roller 5.
The transfer paper 10 is passed through, and a fixing device 11 is provided on a discharge path of the transfer paper 10.

The photosensitive drum 1 includes an inorganic photosensitive drum in which a photosensitive layer such as selenium or amorphous silicon is provided on a conductive base roller such as aluminum, a charge generating agent or a charge transporting agent in a binder resin. An organic photosensitive drum provided with an organic photosensitive layer in which is dispersed is used. As the main charging device 2, there is a roller-type contact charging device, but generally, a corona charger is used, and the main charging device 2 causes the surface (photosensitive layer) of the photosensitive drum 1 to change the type of the photosensitive layer. , And is uniformly charged to a predetermined polarity. At this time, the main charging potential on the photosensitive member surface is usually 700 to 800 V (absolute value). Next, the image exposure mechanism 3 irradiates the surface of the photoreceptor drum with dot light such as a laser beam corresponding to the original by reflected light of the original or an electric signal from a computer or the like. A latent image is formed. In the developing device 4, a developer conveying sleeve is disposed so as to face the photosensitive drum 1, and the developing sleeve supplies developer to a developing area between the photosensitive drum 1 and the sleeve. The development of the electrostatic latent image is performed. As the developer, a two-component developer composed of a magnetic carrier and an insulating toner and a one-component developer composed of a magnetic toner are generally used, and a triboelectrically charged toner is used for a magnetic brush adjusted to a fixed spike length. The toner is used to develop an electrostatic latent image, and the photosensitive drum 1
A toner image 15 is formed on the surface of. The charge polarity of the toner, that is, the toner image 15 is opposite to the charge polarity of the surface of the photosensitive drum 1 when image formation is performed by so-called regular development, and when the image formation is performed by reverse development, It has the same polarity as the charging polarity on the surface of the photosensitive drum 1.

The transfer roller 5 is a metal roller, a conductive powder such as a metal powder or a carbon powder, or a resin or rubber to which conductivity is imparted by the addition of ions, or a roller formed from a foam thereof. , A transfer voltage is applied by a DC power supply 20, and generally 100 to 3000 V
(Absolute value), and in this state, the transfer paper 1 passing between the transfer roller 5 and the photosensitive drum 1 is transferred.
The toner image 15 is transferred onto the image No. 0, and a transferred toner image 16 is formed. The transfer roller 5 is disposed so as to follow the rotation of the photosensitive drum 1, and the distance between the surface of the transfer roller 5 and the surface of the photosensitive drum 1 is 0.1 to 0.5 mm or less, particularly 0.1 mm or less.
It is preferable that the distance is set to be about 0.3 mm. If the distance is smaller than the above range, the toner image 15 is pressed against the surface of the transfer paper 10 passing between the two, and the toner particles are pushed outward, so that the transferred toner image 16 is liable to cause a void or the like. Further, the transfer roller 5 is liable to shake or the like due to an impact when the transfer paper 10 is passed, so that transfer unevenness is easily generated. On the other hand, if this interval is larger than the above range, it becomes difficult to perform transfer effectively.

The transfer paper 10 having the transfer toner image 16 is
The transfer toner image 16 is conveyed to the fixing device 11 and is fixed on the surface of the transfer paper 10 by heat, pressure or the like. On the other hand, after the toner image 15 is transferred onto the transfer paper 10, the surface charge of the photosensitive drum 1 is removed by light irradiation by the charge removing device 6. Further, if necessary, the toner remaining on the surface of the photosensitive drum 1 is scraped and collected by the cleaning device 7 having a cleaning blade or the like, and the next image forming process is performed. The toner collected by the cleaning device 7 is recycled to the developing device 4 as needed, and is reused.

In FIG. 2, which shows the arrangement of the transfer paper transport path for suitably carrying out the transfer method of the present invention, the shaft of the transfer roller 5 is rotatably held by a predetermined frame 30 and at the same time. An insulating guide plate 31 is mounted on the frame 30. The guide plate 31 is located in the vicinity of the transfer roller 5 so that the above-described distance is maintained between the transfer roller 5 and the photosensitive drum 1, and the transfer paper is transferred to the transfer roller 5. It has a guide surface 31a so that it can be smoothly introduced into a small gap between the photosensitive drum 1 and the surface thereof. The reason why the guide plate 31 is insulative is that if it is formed of a conductive member, a current leak or the like occurs, and inconveniences such as poor transfer are likely to occur. Therefore, the guide plate 31 is made of various insulating resins, for example, ABS resin.

On the other hand, the transfer paper 10 is transferred from a predetermined cassette (not shown) to a transfer area (between the transfer roller 5 and the photosensitive drum 1) along a transport path (indicated by A in FIG. 2). The paper is removed after the transfer, and the paper is removed after the transfer. A paper dust removing device 40 and a static eliminator 50 are disposed in the transport path A. After that, it is introduced into the transfer area.

In the present invention, the paper dust removing device 40 comprises a pair of insulating rollers 41, 41 arranged facing each other.
One is a driving roller and the other is a driven roller, and rotates so as to send out the transfer paper 10 passing between them in the direction of the transfer area. Note that the insulating roller only needs to have an insulating surface, and for example, a metal roller or the like whose surface is covered with an insulating resin or elastomer may be used. Further, a conductor roller can be used instead of the insulating roller, but when the conductor roller is used, this conductor roller must not be grounded. This is because if the conductive roller is grounded, the paper dust removing effect is lost.

A scraping member 42 for removing paper dust scraped from the transfer paper 10 is pressed against the surfaces of the insulating rollers 41, 41. Scraping member 4
It is usually preferable that 2 is formed of a cushioning insulating member such as a sponge, a felt, and a brush.

The static eliminator 50 is made up of a conductive member 51, and is disposed on the back side (the side opposite to the transfer surface) of the transfer paper 10 being conveyed. The conductive member 51 is grounded. It is kept at zero potential. That is, the transfer paper 10 is frictionally charged by the frictional contact with the above-described insulating roller 41, but the charged charges of the transfer paper 10, particularly, the charged charges on the back side are removed by the conductive member 51.

The conductive member 51 is formed of a conductive brush or a conductive needle made of a good conductor such as a metal, or a resin film formed of a resin composition in which conductive powder is dispersed. However, the leading end thereof has such an interval that electric charge leaks from the back surface of the transfer paper 10 being conveyed,
For example, they are arranged so that the distance from the back surface is 2 mm or less. Most preferably, the tip of the conductive member 51 is
It is preferable that the contact portion be disposed so as to be in contact with the back surface of the zero. Further, the width of the conductive member 51 is preferably at least approximately equal to the width of the transfer paper. By providing the conductive member 51 having such a wide width, it is possible to perform charge elimination on substantially the entire surface (particularly, the rear surface) of the transfer paper 10.

In the present invention, the transfer paper 10 from which the paper dust has been removed is neutralized as described above, and then supplied to the transfer area, whereby the guide plate 3 is brought into contact with the transfer paper 10.
1 is effectively suppressed, and as a result, the toner is prevented from adhering to the guide surface 31a of the guide plate 31 without adversely affecting the transfer efficiency. It can be prevented. Although not particularly shown, the paper dust removing device and the static eliminator described above can be mounted on a machine frame of an electrophotographic apparatus, or they can be mounted on an integrated unit frame and mounted inside the apparatus. .

[0023]

The transfer method of the present invention effectively removes paper dust from transfer paper, and is particularly effectively applied to an electrophotographic apparatus using a toner recycling method or a cleanerless method. The toner contamination on the back surface can be effectively prevented without adversely affecting the transfer efficiency.

[Brief description of the drawings]

FIG. 1 is a diagram showing an outline of an overall arrangement of an electrophotographic apparatus.

FIG. 2 is a diagram showing an arrangement of a transfer paper transport path for suitably executing the transfer method of the present invention.

[Explanation of symbols]

 1: photosensitive drum 5: transfer roller 10: transfer paper 31: guide plate 40: paper dust removing device 41: insulating roller 50: static eliminator 51: conductive member

Claims (5)

[Claims] A transfer roller is disposed facing the surface of a photoreceptor drum, the transfer roller is maintained at a potential having a polarity opposite to the polarity of the charged toner, and a guide made of an insulating member is provided near the transfer roller. A transfer sheet is guided by the guide plate into a gap between the transfer roller and the photosensitive drum, and the transfer paper is passed through the gap to form an electrostatic latent image on the surface of the photosensitive drum. Transferring the formed toner image from the surface of the photosensitive drum to the surface of the transfer paper, comprising: a paper dust removing device including a pair of paper dust scraping rollers on a transfer path of the transfer paper; A static eliminator made of a conductive member, and removing the paper dust adhering to the transfer paper through the space between the paper dust scraping rollers, and then removing the transfer paper from the conductive member. Or contact Or passing the sheet in the vicinity of the conductive member, and thereafter, transferring the transfer sheet by passing through the gap between the transfer roller and the photosensitive drum via the guide plate. 2. The transfer method according to claim 1, wherein the conductive member is disposed at a position opposite to a transfer surface of the transfer paper. 3. The transfer method according to claim 1, wherein the conductive member is a conductive brush, a conductive film, or a conductive needle. 4. The transfer method according to claim 1, wherein the conductive member has a width at least as large as the width of the transfer paper. 5. The transfer method according to claim 1, wherein the paper dust scraping roller is an insulating roller.