JP2624233B2 - Image forming method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary of the Invention] Magnetic toner development is performed simultaneously with image exposure from the back surface of a photoconductor in which a transparent substrate, a transparent conductive layer, a photoconductive layer, and an insulating layer are sequentially laminated, and thereafter, unexposed portion toner is removed. To obtain a good donor image with almost no fog on the photoreceptor.

[Industrial applications]

The present invention relates to an image forming method, and more particularly to an image forming method in which an image is exposed from the back side of a transparent base photoconductor, a normal magnetic toner development is performed, and then a non-exposed portion toner is removed.

[Conventional technology and problems]

Conventionally, as a method for forming a toner image simultaneously with image exposure, there is an image forming method as shown in a series of proposals such as Japanese Patent Application Laid-Open No. 57-119375. FIG. 3A shows an image forming apparatus for implementing the method disclosed in this publication.

A photoconductor 1 in which a transparent conductive layer 1b is provided on a transparent substrate 1a, and a sufficiently thick photoconductive layer 1c and a surface layer 1d are sequentially laminated thereon.
Brush developer 2 filled with conductive magnetic toner 3
Are arranged facing each other. With a developing bias applied by the power supply 4 between the developing device 2 and the transparent conductive film 1b, image exposure is performed using the image exposing means 5 arranged on the back surface of the photoreceptor 1.
Then, as shown in FIG. 3B, in the exposed portion, photocarriers generated in the photoconductive layer 1c move toward the surface and become latent image charges. At the same time, the toner charged to the opposite polarity to the latent image charge adheres to the surface of the photoconductor 1 to form a toner image 6.

On the other hand, in the non-exposed area, the photoconductive layer 1c is thick, so that the electrostatic attraction is weak, and the toner adhering to the photoconductor 1 is small. As a result, a toner image 6 corresponding to the image exposure is formed on the photoconductor 1.

In the above-described method, image formation is performed using a difference in electrostatic attraction acting on toner in an exposed portion and a non-exposed portion. Therefore, to reduce fog, the photoconductive layer needs to be quite thick. However, a photosensitive member having a large film thickness is difficult to manufacture uniformly, and it is necessary to increase the recording voltage as the film thickness increases.

Thus, fogging is a problem in the conventional method. Therefore, solid development using polyethylene terephthalate as a recording film was performed. The result is shown in FIG. As can be seen from FIG. 4, toner adhesion occurs even when the film thickness is increased and the recording voltage is decreased. Therefore, in the above-mentioned conventional method, since an electric field is applied to the non-exposed portion although it is weak, it is difficult to eliminate fogging.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image forming method in which a photoconductive layer constituting a part of a photoreceptor is thinned to obtain an image with little fog by simultaneously performing exposure and development using a transparent base photoreceptor. .

[Means for solving the problem]

According to the present invention, there is provided a photosensitive member in which a transparent conductive layer, a photoconductive layer, and an insulating layer are sequentially laminated on a transparent substrate. Developing machines are arranged so as to face each other, and image exposure is performed using the image exposing means in a state where a voltage is applied between the first developing machine and the transparent conductive layer, and an interface between the photoconductive layer and the insulating layer is provided. Forming a latent image charge image in the vicinity and applying magnetic toner development,
Next, a toner image is formed on the photoreceptor by removing the toner adhered to the non-exposed portion using a second developing device, and is left on the photoreceptor in a transfer step to a recording medium after the previous image formation. Image forming, wherein in order to erase the toner and the latent image charge, the corona discharge from the insulating layer side and the light discharge from the transparent substrate side are simultaneously performed on the same portion of the photoconductor. Settled by law.

5A and 5B show the principle of image formation according to the present invention.
In particular, FIG. 5A is a schematic diagram showing an exposure and development process, and FIG. 5B is a schematic diagram showing a contrast development process.

In the image exposure step shown in FIG. 5A, magnetic toner development is performed simultaneously with image exposure. First, a transparent substrate 11a such as glass, acrylic, or polyethylene terephthalate, a transparent conductive layer 11b such as an indium oxide vapor-deposited film, a Se-based / cds-based a-Si
A transparent base photoconductor 11 composed of a photoconductive layer 11c such as an organic photoconductor and a thin insulating layer 11d such as polyethylene terephthalate is provided. A first magnetic brush developing device 12 filled with a magnetic toner 13 is disposed on the photoconductor 11, and a developing bias is applied by a power source 14 between the developing device 12 and the transparent conductive film 11b. In this state, image exposure is performed using image exposure means 15 such as a laser optical system and an LED (light emitting diode) array optical system.

Then, in the exposed portion, photocarriers generated in the photoconductive layer 11c move toward the surface and become latent image charges 16 (negative charges in the figure). At the same time, a reverse charge is induced in the magnetic toner 13 and adheres to the exposed portion to form a toner image 17. On the other hand, the developing device 12 and the transparent conductive film 11
Since an electric field acts between b, the toner 18 adheres.

In the contrast development step shown in FIG. 5B, the magnetic toner
The magnetic brush developing machine 19 filled with 20 is set to the same potential as the transparent conductive layer 11b, so that the toner 18
Is recovered by electrostatic attraction and magnetic force. At this time, a small amount of the toner 17 in the image area is also collected, but most of the toner remains on the photoconductor 11 to form the toner image 17 because the electrostatic attraction of the latent image charge 16 and the charge of the attached toner 17 is strong. Is done.

In the case where the insulating layer 11d shown in the present invention is not provided, the positive charge and the negative charge of the exposed portion toner 17 are slightly increased due to dark decay of the photoconductive layer 11c during image exposure and during the transition to the subsequent contrast development. The trapped charges 16 combine and neutralize. As a result, the electrostatic attraction of the exposed portion toner 17 is weakened. Therefore, during the contrast development, the exposed portion toner 17 is collected by the developing device 19, and a sufficient image density may not be obtained. Therefore, the provision of the insulating layer 11d is effective in preventing charge coupling and increasing image density.

According to the present invention, as described above, in order to erase the toner and the latent image charge remaining on the photoreceptor in the transfer process to the recording medium after the previous image formation, the corona discharge from the insulating layer side and the transparent substrate side And at the same time, light is removed from the same portion of the photoconductor. Accordingly, the corona charge removal and the light charge removal can be completely performed on the same portion of the photoconductor, so that the charge removal efficiency is significantly improved.

If, for example, both the corona charge removal and the light charge removal were performed from the insulating layer side without adopting the configuration of the present invention, the latent image charge of the photoreceptor had to be erased from above the residual toner. In order to erase both the charge of the toner and the charge of the latent image on the photosensitive member, the charge must be removed with stronger light, so that the photosensitive member deteriorates early. Alternatively, if only corona charge was removed from both surfaces of the photoreceptor, it would be effective to remove the electric charges charged by friction on both surfaces of the photoreceptor. Therefore, the latent image charge in the photoconductor cannot be removed.

In the present invention, the corona charge is removed from the insulating layer side of the photoreceptor, and the light removal is performed simultaneously from the transparent substrate side of the photoreceptor to the same portion. And the latent image charge of the photoreceptor can be reliably and efficiently removed.

〔Example〕

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic diagram for explaining a first embodiment of the image forming method according to the present invention.

In FIG. 1, the transparent base photoreceptor 21 has a thickness of 100 μm.
It comprises a transparent substrate 21a of m-polyethylene terephthalate, a transparent conductive layer 21b of an indium oxide deposited film, an organic photoconductive layer 21c having a thickness of 10 μm, and an insulating layer 21d having a thickness of 0.5 μm. The photoconductor 21 has an endless belt shape, rotates in the direction of the arrow, and the transparent conductive layer 21b is connected to the ground. The first magnetic brush developing device 22 has a dual structure of a magnet roller and a sleeve, and an inner magnet roller rotates. The developing device 22 is filled with a conductive magnetic toner having a resistance of about 10 ⁶ Ω · cm, and the power supply 23 supplies the sleeve with +200 to +3.
A developing bias of 00V is applied. Image exposure device 24
Is composed of an LED array optical system. Photoconductor insulating layer 21d
The toner image 25 is adhered to the upper exposed portion, and the toner image 25
Latent image charge 26 on the surface of the organic photoconductive layer 21c so as to face the surface.
However, a toner image 27 is formed in the non-exposed area.

The second magnetic brush developing device 28 for removing the toner 27 in the non-exposed portion has the same configuration as the first developing device 22 and is filled with the same toner, and the sleeve is connected to the ground. The toner image 29 from which the toner 27 attached to the non-exposed portion has been removed moves with the rotation of the photoconductor 21.

30 is a recording paper, 31 is a conductive rubber roller for transfer, and a photoconductor
It is pressed at a constant pressure in the direction of 21. Transfer roller
A voltage (−200 to −600 V) having a polarity opposite to that of the developing bias is applied to the toner image 33 by a power supply 32, and the toner image 33 electrostatically transferred onto the recording paper 30 is fixed by a pressure fixing device 34. An image record 35 is semipermanently obtained on the recording paper 30. 36 is a photoconductor after transfer
21 is the residual toner remaining on the surface. Reference numeral 37 denotes a static elimination light source for releasing the latent image charge 26. 38 is an AC corona discharger for removing toner charge, and 39 is its power supply. Reference numeral 40 denotes a toner image that has lost electrostatic attraction due to static elimination.

Hereinafter, the image forming method according to the present invention will be described step by step.

First, the photoconductor 21 is rotated in the direction of the arrow. In the exposure / developing process, the toner is conveyed by rotating the magnet roller of the first developing device 22, and the image exposure is performed according to the image pattern using the image exposure device 24 with the developing bias applied to the sleeve. Then, in the exposure section,
Photocarriers generated in the photoconductive layer 21c move toward the surface and become latent image charges 26. At the same time, the toner charged to the opposite polarity to the latent image charge 26 adheres to the surface of the photoconductor 21 to form a toner image 25. On the other hand, in the non-exposed area, the developing machine 22
Since an electric field acts between the transparent conductive layer 21b and the transparent conductive layer 21b, the toner 27 adheres.

Next, in the contrast developing step, the toner is conveyed to the second developing device 28 connected to the ground, and the non-exposed portion toner 27 is collected by the electrostatic force and the magnetic force. At this time, although the image portion toner 25 is also slightly recovered, most of the image portion toner remains on the photoconductor 21 to form a good toner image 29 because the electrostatic attraction with the latent image charge 26 is strong.

Thereafter, the toner image 29 is electrostatically transferred onto the recording paper 30 using the transfer roller 31, and the toner image 33 captured by the fixing device 34 is transferred.
Is fixed on the recording paper 30. As a result, a semi-permanent recorded image 35 is obtained.

On the other hand, after the transfer, the residual toner 36 remaining on the photoconductor 21 is
Since the charge of the toner 36 and the latent image charge of the toner 36 are removed by the charge elimination light source 37 and the corona charge eliminator 38,
The toner 36 is collected by the developing device 22 which does not lose the electrostatic attraction. The next image formation is performed simultaneously with toner collection. Performing the recovery of the residual toner 40 and the exposure and development at the same time as described above cause no problem since the image exposure device 24 is on the back surface of the photoconductor 21.

In this example, despite the use of a thin and inexpensive organic photoconductor for the photoconductive layer, image recording with little fog and sufficient contrast was obtained.

Hereinafter, a second embodiment of the image forming method according to the present invention will be described as a second embodiment.
Description will be made based on the drawings.

In the second embodiment, a developing device 41 in which a first developing device 22 and a second developing device 28 are integrated in the first embodiment is used.

As shown in FIG. 2, since the exposure development position and the contrast development position are close to each other, the toner removal efficiency is improved. That is, the photoconductor has considerable dark decay. The dark decay occurs because an electric field is formed in the photoconductive layer 21c by the electric charge of the non-exposed portion toner 27 between the exposure development and the contrast development, and the electric charge moves. The electric charge moves to the boundary surface between the photoconductive layer 21c and the insulating layer 21d, and is combined with the electric charge of the toner 27, so that it is difficult to remove the toner 27 in the contrast development process. Accordingly, removing the non-exposed portion toner 27 as soon as possible after the exposure and development removes the toner 27 during dark decay, thereby improving the removal efficiency.

In addition, in the present embodiment, the effect of downsizing the apparatus by integrating the two developing units is provided. Further, by providing a means for transporting the toner collected by the second developing unit 28 to the first developing unit 28, Thus, the toner can be reused.

〔The invention's effect〕

As described above, since an image is formed by the exposure and development steps and the contrast development step, even when a thin photoconductive layer is used, a toner image with almost no fog and sufficient image density can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic diagram for explaining a first embodiment of the image forming method according to the present invention, and FIG. 2 is a schematic diagram for explaining the first embodiment of the image forming method according to the present invention. FIG. 3A and FIG. 3B are schematic diagrams for explaining the conventional method, FIG. 4 is a graph showing fogging investigation results using the conventional method, and FIG. 5A and FIG. FIG. 2 is a schematic diagram illustrating an image forming principle according to the first embodiment. 1,11 ... Photoconductor, 1a, 11a, 21a ... Transparent substrate, 1b, 11b, 21b
... Transparent conductive layer, 1c, 11c, 21c ... Photoconductive layer, 2 ... Magnetic brush developing machine, 3 ... Conductive magnetic toner, 4,14,23,32 ...
... power supply, 5, 15, 24 ... image exposure means, 11d, 21d ... insulating layer, 12, 22 ... first magnetic brush developing machine, 13 ... magnetic toner, 16, 26 ... latent image charge, 17 ... Exposure area toner, 18 ...
... toner 19, developing machine 25, toner image 27, non-exposed part toner 28, second magnetic brush developing machine 29, 33
... toner image, 30 ... recording paper, 31 ... conductive rubber roller for transfer, 34 ... pressure fixing machine, 35 ... image recording, 36 ... residual toner, 37 ... light source, 38 ... AC corona discharge Electrical appliances.

 ──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Junzo Nakajima 1015 Uedanaka, Nakahara-ku, Kawasaki City Inside Fujitsu Limited (56) References JP-A-58-98747 (JP, A) JP-A-60-22146 (JP) JP-A-57-70556 (JP, A) JP-A-58-220154 (JP, A) JP-A-57-129459 (JP, A)

Claims (1)

(57) [Claims] 1. A photoconductor in which a transparent conductive layer, a photoconductive layer, and an insulating layer are sequentially laminated on a transparent substrate, has an image exposing means facing the transparent substrate, and a first developing machine facing the insulating layer. And image exposure is performed using the image exposure means while a voltage is applied between the first developing machine and the transparent conductive layer, and a latent image charge is provided near the interface between the photoconductive layer and the insulating layer. Forming an image, developing the toner with magnetic toner, and then using a second developing device to remove the adhered toner from the non-exposed portion to form a toner image on the photoconductor, and further, a recording medium after the previous image formation. In order to erase the toner and the latent image charge remaining on the photoreceptor in the transfer step to the photoreceptor, a corona discharge from the insulating layer side and a light discharge from the transparent substrate side are applied to the same portion of the photoreceptor. An image forming method which is performed simultaneously.