JPS61122670A - Picture forming device - Google Patents

Abstract

PURPOSE:To obtain the negative and positive images of an original simultaneously by transferring an image by magnetic force simultaneously with picture exposure, and then transferring the image again by magnetic force simultaneously with full exposure. CONSTITUTION:A toner carrying belt 2 is uniformly triboelectrified by a corona discharger 4 and a developing device 5 adheres photoconductive magnetic toner to the belt 2. Then, the belt 2 reaches an image exposure position and the image of an original is projected through an optical system 8. Simultaneously, a light irradiated toner 25a is transferred to a drum 9 side. The toner 25a is carried to the transfer position of a transfer roller 14 and transferred to transfer paper 13. The belt 2 reaches the position of a drum 10 and a photoconductive magnetic toner 25b is transferred to the drum 10 by the light irradiation from a full exposure lamp 11. The toner 25b is transferred also to the transfer paper 13.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a novel image forming apparatus that forms an image of a document.

<Prior art> An electrophotographic copying machine uniformly charges a photoreceptor, which is a recording medium, and has a photoconductive layer, and exposes the image of a document onto the charged surface, thereby making the image correspond to the image on the surface of the photoreceptor. This latent color image, which had formed an electrostatic latent image, is developed with toner, which is an attached pigment, and the developed image (toner image) is transferred to, for example, a transfer machine. The transfer material onto which the toner image has been transferred is conveyed to a fixing section,
The unfixed image on the transfer material is fixed. Electrophotographic copying machines form images in this manner.

In response, Xerox Corporation has proposed a process in which image formation is performed using photoconductive toner instead of using a photoreceptor. This image forming method is Photoacti
ve Pigment Electropotogr
As aphy (abbreviated as PAPE), “Photog
RAPHIC SCIENCE AND EEGINEE
ring Volume 27 Number 5
September loctober 1983P
185-188'' This PA'PE method uses a developer in which photoconductive toner is dispersed in an insulating liquid, and uses polyethylene terephthalate (abbreviated as P).
ET) After depositing the photoconductive toner on the entire surface,
Image exposure is performed and photoconductive toner is transferred to the surface of the metallic drum. At this time, the PET of the toner irradiated with light
The adhesion on the film weakens and the toner is transferred to the metal drum. The toner on the metal drum is transferred to a transfer material.

In the above process, a liquid development method is used to adhere the photoconductive toner onto the PET, but the image density is low and the toner irradiated with light is transferred to the metal drum, so the original A negative image is formed in contrast to the positive image. According to such a developing method, since the particle size of the toner used is very small, about 002 to 2 μm, it is very difficult to obtain an image density of 1.0 or more, which is necessary for practical use.

Furthermore, the toner in the liquid was electrophoretically charged.
The particles move and adhere to the PET film, but because the moving time is slow, the image forming time becomes longer.In particular, if the PET film moves quickly, sufficient image density cannot be obtained.

<Object of the Invention> The present invention provides a novel image forming method using a photoconductive magnetic toner instead of a photoreceptor.

<Embodiment> FIG. 1 is a sectional view showing the overall structure of an image forming apparatus according to the present invention. In the figure, 1 is a reel for winding up the toner conveying belt 2 involved in image formation, and 3 is a reel facing the reel 1 and winding up the toner conveying belt 2 after conveying it to each process at a constant speed. The toner conveying belt 2 is made of a material that transmits light. For example, as shown in FIG. 2, the belt 2 has a structure in which a transparent insulating film 2-1 is overlaid with a highly transparent conductive material 2-2. The transparent insulating film 2-4 is made of polyethylene terephthalate (also known as PET), a conductive material 52-
As the material 2, Show or the like can be used. In order to provide flexibility, a polypyrrole-based conductive material is convenient, but the metal film described above can also be used.

The toner conveying belt 2 has a layer of conductive material 2-2 grounded.

Various devices for image formation are arranged along the conveyance path between the reels 1 and 3 of the toner conveyance belt 2. First, as a first step, a corona discharger 4 is provided to charge the belt 2 to a specific polarity in order to uniformly adhere the photoconductive toner to the toner conveying belt 2.

In the next step, a developing device 5 is provided that applies photoconductive magnetic toner to the uniformly charged belt 2. This developing device 5 is a well-known magnetic brush developing device, and is equipped with two stirring rows 25-2 in a developing tank 5-1, and is capable of conveying photoconductive magnetic toner to two surfaces of the belt for development. A developing roller 5-3 is provided. In particular, in the developing row 25-3, a magnet is provided in a non-magnetic sleeve, and the magnetic photoconductive toner is attracted to the sleeve surface using the magnetic force of the magnet, and the sleeve is rotated in the direction of the arrow. The photoconductive toner, which is itself magnetic, is transported to a toner transport belt 2. The developing roller 5-3 facing the belt 2 forms a photoconductive magnetic toner as a developer into a brush shape along the lines of magnetic force of the magnetic poles of an internal magnet 7, and brings this into sliding contact with the belt 2. It turns out.

Therefore, photoconductive magnetic toner adheres to the charging surface of the toner conveying belt 2, and development is performed.

After the above-mentioned development of the toner conveying belt 2, image exposure is performed from the surface of the back surface of the conductive material 2-2 of the belt 2.

Image exposure is performed by illuminating the original held in the original holding unit 6 with an illumination device 7 that irradiates the original with light, and directing the reflected light from the original to the toner conveying belt 2 through an optical system 8 consisting of a reflecting mirror and a projection lens. The image is formed on the back. When exposing an image to the moving toner conveying belt 2, the document holding section 6 is moved in accordance with the movement of the belt 2 as in the past, or a part of the optical system 8 is moved to scan and expose the image on the document. You can do it like this. At this exposure position, a drum 9 is placed in contact with the surface of the belt 2 to which the toner is attached. The drum 9 is rotationally driven in the direction of the arrow along the conveying direction of the toner conveying belt 2. Further, the drum 9 is formed of a magnet in order to magnetically transfer photoconductive magnetic toner onto the drum 9. Further downstream of the drum 9, that is, after the transfer to the drum 9, a drum 10 having the same structure as the drum 9 is arranged so as to be in contact with the toner adhering surface of the toner conveying belt 2. The drum 10 is also rotationally driven in the direction of the arrow along the conveyance direction of the belt 2. On the back side of the belt 2 at the contact portion between the drum 10 and the toner transport belt 2, a full-surface exposure lamp 11 is disposed to uniformly irradiate the entire belt 20 in the width direction (direction perpendicular to the transport direction).

Further downstream of the drum 10, an AC corona discharger 12 for static elimination is arranged facing the insulating layer surface of the toner conveying belt 2. The corona discharger 12 is preferably one that performs alternating current corona discharge, but it may be one that performs corona discharge of opposite polarity to the corona discharger 4 for charging.

The corona discharger 12 is for removing the electric charge remaining on the toner transport belt 2, and is useful for using the belt 2 again. Therefore, it is convenient to provide a cleaning device (not shown) for removing the toner remaining on the toner conveying belt 2 after the action of the corona discharger 12.
The drums 9 and 10 are subjected to imagewise exposure and uniform exposure, so that toner images corresponding to the exposed images are transferred to the drums 9 and 10. drum 9
The upper toner image is transferred onto the transfer paper 13 by the action of the transfer roller 14 . Then, the transfer paper 13 is separated by the drum 9 and fixed to the paper a-, 716 via the paper conveyance belt 15.
The toner image on the upper surface is fixed. Some toner remains on the drum 9 after the transfer, and a cleaning device 17 is disposed to remove this toner and bring the clean surface of the drum 9 into contact with the toner conveying belt 2 again. The toner image transferred to the drum 10 is transferred by a transfer roller 19 to a transfer paper 13 that is sent by a conveyance roller 18. Then, the transfer paper 13 is separated from the drum 1 and transferred to the fixing roller 221 via the paper conveyance belt 20.
The toner image on the upper surface is fixed. Similar to the drum 9, some toner remains on the drum 10 after the transfer, and a cleaning device 22 is disposed to remove this toner.

In the image forming apparatus configured as described above, the operation will be explained below by showing an example.

100 The toner conveying belt 2 is conveyed between the reels 1 and 3 at a constant speed of /(8) in the left direction in the figure by the action of the reel 3. The surface of the toner conveying belt 2 is first uniformly charged by the action of corona discharge from the corona discharger 4. In this case, the surface potential of the toner conveying belt 2 is +700VK.
It is charged uniformly so that

Next, the developing device 5 attaches photoconductive magnetic toner according to the surface potential of the charged toner conveying belt 2. In particular, the photoconductive magnetic toner is triboelectrically charged to a polarity opposite to the potential of the toner conveying belt, for example, by the action of the stirring roller 5-0 and the like. Therefore, the photoconductive magnetic toner is attracted and adhered to the toner conveying belt 2.

After development, the toner conveying belt 2 reaches the image exposure position, and the image of the original on the original holding section 6 is projected via the optical system 8. At this time, the reflected light from areas other than image areas such as character areas (reflected light from non-image areas) is irradiated onto the toner conveying belt 2, so the photoconductive magnetic toner 25a in the irradiated areas is The value drops significantly. However, the resistance value of the photoconductive magnetic toner 25b in the portion corresponding to the image area remains high. Therefore, the portion of the toner 25b that has not been irradiated with light is not transferred to the drum 9 because the Coulomb force between the charge on the belt 2 and the charge of the toner itself is very strong. On the other hand, the toner 25a that has been irradiated with light has a low resistance, loses a part of its charge, and the bond due to the Coulomb force due to the charge on the belt 2 is weakened, and the magnetic attraction force of the toner 25a to the drum 9 is reduced to the belt 2. The toner 25a overcomes the Coulomb force between the toner 25a and is transferred to the drum 9 side.

Here, the photoconductive magnetic toner used has a toner particle size of 12 μm on average, and development is carried out using a magnetic brush of 100, so even if the belt 2 is run in a 7-type system, the developing roller is The toner 25 on the belt 25-3 can be formed in several layers (see FIG. 3) on the belt 2. Therefore, the image density can be made sufficiently higher than in the past. Further, the toner has a volume resistivity of at least 10'Ω or more in a dark place,
It is suitable that the material exhibits a volume resistivity of 0 to 10,100[alpha] when exposed to light, that is, when exposed to light. As a result, the toner 25a irradiated onto the drum 9 was effectively transferred by magnetic force.

Further, the toner 25a of the light irradiation part of the photoconductive magnetic toner is
In order to effectively transfer the image to the drum 9, a voltage 24 is applied between the drum 9 and the conductive material 2-2 on the back surface of the belt 2, as shown in FIG.

In this case, the applied voltage is applied such that the voltage on the drum 9 side is positive so that the polarity is opposite to the negative charge charged on the photoconductive toner. Therefore, the irradiated photoconductive magnetic sheet f-25a is attracted to the drum 9 side by the applied voltage and the magnetic attraction force, thereby increasing the transfer efficiency.

On the other hand, the toner 25a in the light irradiated portion transferred to the drum 9
is sent to the transfer position of the transfer roller 14 as the drum 9 rotates, and is transferred onto the transfer paper 13 that is being conveyed as appropriate. The toner image 25a transferred to this transfer paper 13 is
If it is a non-image without an image and the document is positive, it will be a negative image. In other words, the image transferred to the drum 9 is a reversed image, and a reversed image is obtained on the paper 13.The transfer paper 13 after the zero image transfer is sent to the fixing roller 16 via the conveyor belt 15, and the toner is transferred to the fixing roller 16. The image is fixed and ejected from the machine.

Some toner remains on the drum 9 after the transfer,
This residual toner is removed from the blade 17 of the cleaning device 17.
-0, and collected in the collection box 17-2. Therefore, the surface of the drum 9 is in a clean state and the toner is transported again.

It will come into contact with route 2.

Copies can be obtained as described above, but the resulting images are negative copies for positive originals, positive copies for negative originals, and inverted images.

Therefore, in order to obtain a positive image, the toner conveying belt 2 reaches the position of the drum 10. A full-surface exposure lamp 1 is provided at a position where the drum 10 and the toner conveying belt 2 contact each other.
1, the entire belt 2 is uniformly irradiated with light, and the resistance value of the photoconductive magnetic toner 25b that was not irradiated with light is greatly reduced. Therefore, the electrostatic attraction force between the toner 25b and the belt 2 is weakened, and the toner is magnetically transferred to the drum 10 in contact with the toner 25b. In this step as well, it is effective to apply a voltage sufficient to transfer the toner 25b to the drum 10 as shown in FIG. 3, as in the case of the transfer to the drum 9.

The toner image transferred to the drum 10 is transferred to the conveyance roller 2
The image is transferred onto the transfer paper 13, which is conveyed via the transfer roller 219, by the action of the transfer row 219. Here, the transfer rollers 214 and 19 are used as means for transferring the toner image on the drum 9 or 10 onto the transfer paper 13, but in order to perform electrostatic transfer, a corona discharger is arranged in place of the rollers 14 and 19. It's okay. After transfer to such paper, such transfer paper 13
is separated from the drum 10 and sent to the fixing roller 21 via the paper conveyance bell (20), and after the toner image on the upper surface is fixed, it is discharged outside the machine. In this case, transfer paper 1
The image above 3 is a portion corresponding to the image portion of the original, and is a positive image for a positive original.

Some toner remains on the surface of the drum 10 after the transfer, and the residual toner is scraped off by the grade 22-1 of the cleaning device 22 and collected into the collection box 22-2. Therefore, the surface of the drum 10 comes into contact with the toner conveying belt 2 in a clean state and contributes to image formation.

Further, after the toner 25b has been transferred to the drum 10, the toner conveying belt 2 is neutralized by the action of the AC corona discharger 12, and then wound onto the reel 3.

At this time, in order to reuse the belt 2, it is preferable to provide a cleaning device that removes the toner remaining on the belt 2 after static electricity is removed. After the image formation is completed, the toner conveying belt 2 is rewound onto the reel 1 and reused. but,
The belt 2 may be formed into an endless shape without being rewound by the reel 1, and the belt 2 may be always conveyed in only one direction.

As described above, according to the image forming apparatus of the present invention, it is possible to easily and simultaneously obtain either a positive or negative image of a document.

Note that as a means for fixing the toner image on the transfer paper 13,
Although it was explained as fixed cola 16.21, the low 216
．． Although it is advantageous for 21 to be a heat fixing roller, the present invention is not limited thereto, and it may be a pressure fixing roller. Furthermore, an open fixing method may be used instead of the a-ra method.

Further, the photoconductive toner may be, for example, an organic photoconductive material (OP
It can be prepared by kneading C) and a suitable binder together with a colored pigment, and pulverizing the mixture to a suitable size, that is, in this example, an average particle size of about 12 μm. At this time, the volume resistance in the dark is 108Ω or more, and the volume resistance when irradiated with light is 0~
The mixing ratio with the organic photoconductive material and the coloring pigment is appropriately set so as to be in the range of 10I0ΩG. Moreover, the photoconductive toner having magnetic properties may be formed by further kneading magnetic powder 5 in addition to the above-mentioned materials. Also,
A photoconductive toner having magnetism may be prepared by coating the surface of toner particles consisting of magnetic powder, color pigment, and binder with a thin film of OPC. At this time, if pigments such as cyan, magenta, and yellow are used as coloring pigments,
Color images can be formed.

Furthermore, although the toner on the toner conveying belt 2 is transferred to the drum 9-10, it can also be transferred directly to the paper 13.

The transfer paper is fed into the contact area between the drums 9 and 10 and the belt 2, and the photoconductive magnetic toner 25a or 25b is transferred onto the transfer paper 13 by the force of the drums 9 and 10. With this configuration, the transfer opening ~14', 19
and cleaning devices 17 and 22 can be made unnecessary.

<Effects of the Invention> According to the image forming apparatus of the present invention, in an image forming apparatus using photoconductive magnetic toner, image transfer is performed using magnetic force at the same time as image exposure, and then image transfer is performed using magnetic force simultaneously with full-surface exposure. Since the image transfer is carried out in the transfer material, the formed image can be effectively transferred onto the transfer material, and a negative or positive image can be simultaneously obtained on the original. Therefore, is there only one image like in a conventional electrophotographic copying machine? It can be said that this device is more versatile than anything else you can see.

[Brief explanation of the drawing]

FIG. 1 is a structural diagram showing a specific example of an image forming apparatus according to the present invention, FIG. 2 is a sectional view showing an example of a recording medium on which an image is formed according to the present invention, and FIG. 3 is an example of a toner image transfer example. FIG. 2: Toner transport belt 4:':! Rona discharger 5: Developing device 8: Optical system 9: Metal drum 10: Metal drum 11: Full-surface exposure lamp 12: Static elimination corona discharger 1
3: Transfer paper 25: Photoconductive magnetic toner agent Patent attorney Aihiko Fukushi (and 2 others) Figure 11 Figure 2 Figure 3 Procedural amendment (Dragon) Showa-Kon 13th month of Q.

Claims (1)

[Claims] 1. A means for uniformly charging a light-transmissive recording medium, a developing device for developing the charged surface of the recording medium with a photoconductive magnetic toner, a means for exposing an image to the recording medium, and an exposure position by the exposure means. a first transfer section that simultaneously transfers the photoconductive magnetic toner in the light illumination section (bright section) to a transfer member using magnetic force, and an entire surface exposure section that uniformly irradiates the entire recording medium with light after being exposed by the exposure section. An image forming apparatus comprising: a second transfer section that simultaneously transfers the photoconductive magnetic toner of the recording medium to the transfer member by magnetic force at the exposure position by the entire surface exposure means.