JPS63249871A - Electrophotographic copying method - Google Patents

Abstract

PURPOSE:To miniaturize a device and to reduce the cost by allowing a form to pass through between the surface of a photosensitive body on which an electrostatic latent image has been formed, and a developing device for forming a magnetic brush of a developer, forming a developer image, and thereafter, leading it to a fixing device. CONSTITUTION:When a form 22 passes through between the surface of a photosensitive body 2 on which an electrostatic latent image has been formed, and a developing device 6 for supplying a developer constituted of a toner 32 and a carrier 31, to said electrostatic latent image, the developer inserts and holds the form 22 and adsorbed to an electrostatic latent image. Accordingly, to each of both faces of the form 22, a charge for forming the electrostatic latent image, and the developer are brought to electrostatic adsorption. The form 22 to which the toner 32 has been adsorbed is led to a fixing roller 11, heated and pressed by the fixing roller 11, the thermoplastic toner 32 is melted and fixed to the surface of the form 22, and an image is formed. In such a way, the number of parts of a device for constituting a copying machine 1 is decreased remarkably, and the device is miniaturized and the cost is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION (Al Industrial Field of Application) The present invention relates to an electrophotographic method for copying an image onto paper using electrophotography. By passing the paper through the photoreceptor, the developer is attracted to the electrostatic charge on the surface of the photoreceptor with the paper sandwiched between them, and an image is directly formed on the paper.

(C1 Conventional technology) Copying machines using electrophotography generally sequentially perform charging, exposure, and development steps on the surface of a photoreceptor, and transfer the developer image formed on the surface of the photoreceptor to paper in the transfer process. After the image is transferred onto the paper, a copying process is performed in which the image transferred onto the paper is fixed in a fixing process.After the transfer process, the remaining developer and charge are removed from the surface of the photoreceptor in a cleaning process and a static electricity removal process. As mentioned above,
In order to continuously perform a charging process, an exposure process, a developing process, a transfer process, a cleaning process, and a static elimination process on the surface of the photoconductor, a conventional copying machine has a charger and a developing process installed near the outer periphery of the photoconductor. It is equipped with a device, a transfer charger, a cleaner, and a static elimination lamp (including the case of 10 static elimination charges).

The charger applies a single polarity charge to the surface of the photoreceptor,
In the next exposure step, an electrostatic latent image is formed on the surface of the photoreceptor by light from the original image. The developing device stores developer therein. This developer is charged with a polarity opposite to that on the surface of the photoreceptor. The developing device supplies a developer to the electrostatic latent image on the surface of the photoreceptor to visualize the electrostatic latent image. The transfer charger applies a corona discharge of the same polarity as the charge on the photoconductor surface to the paper guided between it and the photoconductor surface, and transfers the developer electrostatically attracted to the photoconductor surface to the paper surface. . Even after the transfer process is completed, some developer remains on the surface of the photoreceptor, and the charge that formed the electrostatic latent image also remains. The cleaner is equipped with a blade that comes into contact with the surface of the photoreceptor, and the blade scrapes off residual developer. Further, the static elimination lamp removes residual charges on the surface of the photoreceptor by exposure. In addition, in order to peel off the paper adsorbed to the surface of the photoreceptor in the transfer process, a peeling charger that generates an AC corona discharge may be provided near the transfer charger (d1) Copying machines using conventional electrophotographic copying methods require a large number of devices near the outer periphery of the photoreceptor, which has the disadvantage of increasing the size and cost of the device.

An object of the present invention is to form an image directly on paper by guiding the paper between the surface of a photoreceptor and a developing device, omit a developing step in which a developer image is formed on the surface of the photoreceptor, and eliminate the transfer step and It is an object of the present invention to provide an electrophotographic copying method that can realize miniaturization and cost reduction by eliminating the need for cleaning steps and omitting the equipment related to these steps.

(Means for Solving Problem e1) The electrophotographic copying method of the present invention involves passing a sheet of paper between the surface of a photoreceptor on which an electrostatic latent image is formed and a developing device that forms a magnetic brush of developer. The method is characterized in that after forming a developer image on a sheet of paper, the sheet of paper is guided to a fixing device.

In the present invention, a sheet of paper passes between the surface of a photoreceptor on which an electrostatic latent image is formed and a developing device that supplies developer to the electrostatic latent image. Therefore, the developer is attracted to the electrostatic latent image with the paper in between. Therefore, the charge and developer forming an electrostatic latent image are electrostatically attracted to each of both sides of the paper.

(g) Embodiment FIG. 1 is a schematic front sectional view of a copying machine in which an electrophotographic copying method according to an embodiment of the present invention is used.

A photoreceptor drum 2 is located at the center of the interior of the copying machine body 1 as shown by arrow A.
It is rotatable in the direction. This photosensitive drum 2
A charging charger 5, a developing device 6, and a static elimination charger 7 are provided on the outer periphery of the image forming apparatus. Inside the developing device 6,
A stirring roller 6a and a magnet roller 6b are provided. The magnet roller 6b rotates in the direction of arrow E with a magnetic brush formed on its outer peripheral surface.

A paper cassette/gutter 9 is attached to one side of the copying machine main body 1. Paper cassette 9 stores paper therein, and the paper is fed one by one by paper feed roller 8. A paper discharge tray 13 is attached to the other side of the copying machine main body 1. A conveyance roller 10, a fixing roller 1), and a paper discharge roller 12 are provided between the paper cassette 9, the photosensitive drum 2, and the paper discharge tray 13, forming a paper conveyance path.

A document table 14 is provided on the top surface of the copying machine main body 1 so as to be movable back and forth in the directions of arrows B and C. In addition, the copying machine main body 1
A light source 15, a lens 3, and a mirror 4 are provided inside. The light source 15 irradiates the image of the document set on the document table 14 with light. The lens 3 is configured by integrating a converging light transmission body, and guides reflected light from the image of the original to the mirror 4. The mirror 4 irradiates light from the image of the original onto the photosensitive drum 2 in the normal direction.

At the start of the copying process, the document table 14 moves in the direction of arrow B to a position 14a indicated by a chain double-dashed line in the figure, and then moves in the direction of arrow C to a position 14b indicated by a chain dotted line in the figure. During this movement in the direction of arrow C, the image of the original set on the original platen 14 is scanned by the light source 15 and the lens 3.

As the document table 14 moves, the photosensitive drum 2 rotates in the direction of arrow A, and the surface of the photosensitive drum 2 is charged with a monopolar charge by the charger 5 . At the same time, the paper is guided by the paper feed roller 8 toward the transport roller 1O. At this time, the conveyance roller 10 is stopped, and the paper stops with its leading end in contact with the conveyance roller 10.

When the document table 14 starts moving in the direction of arrow C from the position 14a, the surface of the photosensitive drum 2 is irradiated with light from the document image, forming an electrostatic latent image. The conveyance roller 10 starts rotating in synchronization with the rotation of the photoreceptor drum 2, and the paper is guided between the photoreceptor drum 2 and the developing device 6. The timing at which the conveyance roller 10 starts rotating is the timing at which the leading edge of the electrostatic latent image and the leading edge of the paper coincide at a position where the photosensitive drum 2 faces the magnet roller 6b of the developing device 6.

Inside the developing device 6, a developer composed of toner, which is a thermoplastic resin powder, and a magnetic carrier is stored. The toner and carrier are agitated inside the developing device 6 by an agitation roller 6a. By this stirring, the toner is triboelectrically charged with an electric charge of opposite polarity to the electric charge forming the electrostatic latent image, and adsorbed onto the surface of the carrier. Developing device 6
The carrier is attracted to the surface of the magnet roller 6b.
It rotates in the direction of arrow E together with the surface of the magnet roller 6b.

FIG. 3 is a diagram schematically showing a developing process in a copying machine using the above electrophotographic copying method.

An electrostatic latent image is formed on the surface of the photosensitive drum 2 by ten charges. On the other hand, in the developing device 6, the carrier 31 attracts the toner 32 which is triboelectrically charged in a single portion. A sheet of paper 22 is guided between the photosensitive drum 2 and the developing device 6 in the direction of the arrow.

As a result, the ten-charged toner 32 is located on the upper surface of the paper 22, and the single-charged toner 32 is located on the lower surface of the paper 22. The toner 32 is attracted by the electric charge located on the upper surface of the paper 22 and is separated from the carrier 31 and adsorbed to the lower surface of the paper 22. At the same time, the ten charges adsorbed on the surface of the photosensitive drum 2 are adsorbed on the upper surface of the paper 22. The adsorption position of the toner 32 on the bottom surface of the paper 22 is defined by the position of the ten charges located on the top surface of the paper 22, and the position of the ten charges on the top surface of the paper 22 is defined by the electrostatic latent image on the surface of the photoreceptor drum 2. Ru. Therefore, the toner 32 is attracted to the same position as the electrostatic latent image, and the electrostatic latent image formed on the surface of the photosensitive drum 2 is visualized on the lower surface of the paper 22.

The paper 22 to which the toner 32 has been adsorbed is guided to the fixing roller 1). The fixing roller 1) heats and presses the paper 22, melts the thermoplastic toner 32, and fixes it on the surface of the paper 22. The paper 22 with the image fixed in this manner is discharged onto the paper discharge tray 13 by the paper discharge roller 12.

FIG. 2 is a diagram schematically showing the state of image formation in a copying machine using the above electrophotographic copying method.

The image of the document 21 set on the document table 14 is displayed on the document table 1.
4 is scanned when it moves in the direction of arrow C. Therefore, the image of the original 21 is scanned in the direction of arrow B by the light source 15 and lens 3. On the other hand, the photosensitive drum 2 rotates in the direction of arrow A. Therefore, the original 21 by the light source 15 and the lens 3
The scanning direction of the image and the direction in which the electrostatic latent image is formed on the photoreceptor drum 2 are in the same direction with the image as a reference, and an erect electrostatic latent image is formed on the surface of the photoreceptor drum 2.

Since the surface # of the paper 22 on the photosensitive drum 2 side faces this electrostatic latent image, the charges forming the electrostatic latent image are attached to this surface upside down. On the other hand, on the opposite side of the paper 22, toner adheres to the electrostatic latent image that has been turned over from the back side, so the electrostatic latent image that has adhered to the paper 22 is turned over and becomes visible on this side. . Therefore, on the surface of the paper 22 facing the developing device, an electrostatic latent image on the surface of the photoreceptor drum 2, that is, a toner image erected to the original image is formed.

Note that by providing the mirror 4, the image of the original is reversed with respect to the scanning direction, thereby preventing deterioration in the reproducibility of the copied image due to the relative reversal of the scanning direction of the original image and the direction of formation of the electrostatic latent image. are doing.

(h) Effects of the Invention According to the present invention, since no developer image is formed on the surface of the photoreceptor, a transfer step and a cleaning step are unnecessary, and a transfer charger and a cleaner related to these steps can be eliminated. Therefore, the number of parts of the apparatus constituting the copying machine can be significantly reduced, making it possible to reduce the size and cost of the apparatus.

[Brief explanation of drawings]

FIG. 1 is a schematic front cross-sectional view showing the configuration of a copying machine using an electrophotographic copying method according to an embodiment of the present invention, FIG. 2 is a diagram schematically showing an image forming state in the same electrophotographic copying method, FIG. 3 is a diagram schematically showing the developing step in the same electrophotographic copying method. 2-photosensitive drum, 6-developing device.

Claims (1)

[Claims] (1) A sheet of paper is passed between the surface of the photoreceptor on which an electrostatic latent image is formed and a developing device that forms a magnetic brush of developer. After forming a developer image on this sheet of paper, the sheet is transferred to a fixing device. An electronic photocopying method characterized by leading to.