JP2009192697A - Method of forming electrophotograph - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve both of a charging potential of an a-Si electrophotographic photoreceptor and a photomemory phenomenon even when a PS (process speed) is increased. <P>SOLUTION: A method of forming an electrophotograph is disclosed, comprising repetition of the following steps to form an electrophotograph. The steps are: a main charging step of charging the surface of an electrophotographic photoreceptor; followed by an electrostatic latent image forming step of forming an electrostatic latent image on the surface of the electrophotographic photoreceptor; a developing step of developing the electrostatic latent image into a toner image; a transferring step of transferring the toner image onto a recording medium; subsequently, a first discharging step of discharging the electrostatic latent image; then a sub-charging step of charging the surface of the electrophotographic photoreceptor; and a second discharging step of discharging the surface of the electrophotographic photoreceptor. The surface potential of the electrophotographic photoreceptor discharged in the second discharging step is higher than the surface potential of the electrophotographic photoreceptor discharged in the first discharging step. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electrophotographic forming method using an electrophotographic apparatus such as a copying machine, a printer, and a fax machine.

  An electrophotographic photosensitive member having a photosensitive layer made of an amorphous material on a substrate is widely known. As an example, there is an amorphous silicon electrophotographic photosensitive member in which an amorphous material based on silicon atoms formed on a substrate of metal or the like by a film forming technique such as CVD is used as a photosensitive layer. This amorphous silicon electrophotographic photosensitive member is characterized by excellent wear resistance due to its high surface hardness. Therefore, a high-speed electrophotographic apparatus using an amorphous silicon electrophotographic photosensitive member has been commercialized, and many proposals have also been made regarding a method for forming an electrophotographic image using a high-speed electrophotographic apparatus in which the amorphous silicon electrophotographic photosensitive member is rotated at a high speed. Has been made.

  FIG. 7 is a schematic schematic view of a conventional electrophotographic apparatus using an amorphous silicon electrophotographic photosensitive member (hereinafter also simply referred to as an electrophotographic photosensitive member). A conventional electrophotographic forming method will be described with reference to FIG. First, the electrophotographic photosensitive member 701 is rotated, and the surface of the electrophotographic photosensitive member is uniformly charged by the charger 702. Thereafter, the electrostatic latent image means 708 exposes the surface of the electrophotographic photosensitive member to form an electrostatic latent image on the surface of the electrophotographic photosensitive member, and then development is performed using toner supplied from the developing unit 714. As a result, a toner image is formed on the surface of the electrophotographic photosensitive member. Then, the toner image is transferred to a transfer material 712 by a transfer charger 706, the transfer material 712 is separated from the electrophotographic photosensitive member 701, and the toner image is fixed to the transfer material.

  On the other hand, the toner remaining on the surface of the electrophotographic photosensitive member to which the toner image is transferred is removed by a cleaner 711, and then the surface of the electrophotographic photosensitive member is exposed to expose residual carriers at the time of the electrostatic latent image in the electrophotographic photosensitive member. Remove the charge. Image formation is continuously performed by repeating this series of processes.

However, the speedup of the electrophotographic apparatus has progressed, and in the conventional electrophotographic forming method described above,
1. The static charge becomes insufficient, and a photo memory is generated in which the residual carrier generated during exposure in the electrostatic latent image forming process appears on the image during the next process.
2. Due to insufficient charging time, it becomes impossible to apply a sufficient charging potential in the charging process,
3. An image with a low image density may be output.

  For this reason, a technology that relaxes the photo memory by providing a plurality of static eliminators or a plurality of chargers ensures a sufficient charging potential so as not to cause a decrease in image density due to speeding up of the electrophotographic apparatus. Many technologies are disclosed.

  For example, in the case of a selenium photoconductor, in Patent Document 1, a first static eliminator, an auxiliary charger, a second static eliminator, and a main charger are arranged from an exposure source that forms an electrostatic latent image toward the downstream in the rotation direction of the photoconductor. An electrophotographic forming method for an electrophotographic apparatus is disclosed. What is disclosed is that an electronic device capable of realizing high resolution by preventing the generation of a photo memory by using a short-wave discharge light with a first discharger and a long-wave discharge light with a second discharger. This is a method of forming a photograph.

In addition, the first charger, the second charger (transfer charger), the first entire exposure device, the second entire exposure device, and the control device, the first entire exposure device is more than the main charger, Two full-face exposure devices are arranged downstream of the second charger in the direction of movement of the organic photoreceptor, and the control device activates the first and second chargers and the first and second full-face exposure devices prior to image formation. A pretreatment is performed in which charging and entire exposure are performed twice. Thereafter, the charging polarity of the second charger is reversed, and image formation is performed using the first full-surface exposure device as a transfer simultaneous exposure device. Patent Document 2 discloses a technique relating to a method for forming an electrophotographic image that suppresses a decrease in charging potential and improves the stability of the charging potential by performing such pre-processing before image formation.
JP 05-297785 A JP 2003-295535 A

  In recent years, while the market for electrophotographic devices has expanded to the light printing area, due to the growing awareness of ecology, amorphous silicon (also expressed as a-Si) electrophotographic photosensitive members have been used, and the process speed (also expressed as PS) has been conventionally increased. There is a demand for higher speed and higher image quality.

  The technique disclosed in Patent Document 1 changes the generation position of carriers generated by the static elimination light of the first static elimination device and the second static elimination device by changing the wavelength of the static elimination light. This makes it possible to reduce the difference in carrier density in the film between the exposed area and the non-exposed area when forming the electrostatic latent image, so that photo memory (image density unevenness) can be improved.

  On the other hand, the technique disclosed in Patent Document 2 eliminates defects at the molecular level existing in the photosensitive layer of the organic photoreceptor by performing multiple times of charging and overall exposure as preprocessing before outputting the first image. The trapped carrier is removed. As a result, it is possible to reduce the time until the first image is output, compared to the case where the pre-processing is performed by normal one-time charging and overall exposure, and it is possible to suppress the decrease in the first charged charge. Therefore, the charging potential can be improved.

  However, it has been difficult to solve the improvement of the photo memory and the improvement of the charging potential at the same time. Therefore, as the process speed is increased, there may be a problem that the image density unevenness and the image density decrease appear more remarkably.

  Similarly, even when the techniques disclosed in Patent Documents 1 and 2 are used, in an electrophotographic apparatus using an a-Si electrophotographic photosensitive member, when PS is speeded up, image density lowering and image density unevenness are caused. It was difficult to improve simultaneously.

  That is, there is a demand for an electrophotographic apparatus using an a-Si electrophotographic photosensitive member with good wear resistance, high PS, and improved image density unevenness and image density reduction. To increase the speed of PS actually means to increase the rotational speed of the a-Si electrophotographic photosensitive member.

  As a result, when the speed of PS of an electrophotographic apparatus using an a-Si electrophotographic photosensitive member is increased, the following problems are raised.

  First, since the a-Si electrophotographic photosensitive member has a relative dielectric constant larger than that of the organic photosensitive member, in order to set the surface potential of the photosensitive member to a predetermined potential, a larger amount of charge than the organic photosensitive member is exposed. It needs to be supplied to the body surface. However, in a high-speed electrophotographic process, when PS becomes faster, the time for passing through the photoreceptor charger, that is, the time for the charging process is shortened, and the amount of charge supplied from the charger to the photoreceptor surface is reduced. End up. As a result, there is a case where the image density is lowered due to the reduction of the charging potential.

  Secondly, in the a-Si electrophotographic photosensitive member, carriers generated by exposure at the time of forming an electrostatic latent image are trapped in a defect level in the film. The trapped carrier may cancel the surface charge on the charged photoreceptor surface in the charging step. For this reason, a photo memory may occur due to a decrease in the potential of the electrostatic latent image forming unit. When a photo memory is generated, there is a problem that unevenness of image density occurs.

  In order to improve the photo memory, the photoconductor is designed so that the difference between the carrier density trapped in the exposed portion during electrostatic latent image formation and the carrier density trapped in the non-exposed portion during electrostatic latent image formation is reduced. It was necessary to irradiate the whole with static elimination light and generate a large amount of carriers in the film. However, in a high-speed electrophotographic process, since the time from charge removal to charge becomes shorter, the coupling probability between the charge supplied to the surface of the photoreceptor due to charge and the carrier generated by charge removal becomes higher than before. End up. As a result, the difference in trapped carrier density between the exposed portion and the non-exposed portion at the time of forming the electrostatic latent image is not so small as to improve the photo memory, and image density unevenness may occur.

  Therefore, it is necessary to increase the density of carriers generated in the film by static elimination light, but the number of carriers trapped in the defect level increases, but at the same time, the number of carriers trapped in the defect level in the film is higher than the number of carriers trapped in the defect level. Excess carrier remains.

  In a high-speed electrophotographic process, the time required for these excess carriers to recombine is shortened, so that the number of carriers in the film immediately before the charging step becomes excessive as compared with the conventional electrophotographic process. For this reason, these carriers are combined with the surface charge of the photosensitive member during and after charging, and the potential at the developing device position is lower than that in the prior art. As a result, the image density may be lowered.

  It has been found that the above-described phenomenon becomes prominent when the speed of PS is increased, and particularly, when PS becomes 500 mm / sec or more.

As described above, in a high-speed electrophotographic apparatus using an a-Si electrophotographic photosensitive member,
1. Improving image density unevenness with photo memory,
2. Attenuation of charging potential due to carriers generated by static elimination light and improvement of image density reduction due to reduction of charging potential due to shortening of charging time,
It was very difficult to achieve both.

  The object of the present invention is to improve image quality by reducing image density unevenness and image density reduction by improving reduction in photo memory and surface potential of a high-speed electrophotographic apparatus using an a-Si electrophotographic photosensitive member. An object of the present invention is to provide an electrophotographic method that is favorable for environmental performance.

The present invention comprises a main charging step of charging a surface of an electrophotographic photosensitive member having a photoconductive layer and a surface layer made of an amorphous material having silicon atoms as a base on a conductive substrate, and thereafter, electrophotographic photosensitive An electrostatic latent image forming step for forming an electrostatic latent image on the surface of the body, a developing step for developing the electrostatic latent image as a toner image, a transfer step for transferring the toner image to a recording medium, and then an electrostatic latent image. A first charge eliminating step to remove the image, and then
A sub-charging step for charging the surface of the electrophotographic photosensitive member;
A method for forming an electrophotographic image by forming an electrophotographic image by sequentially repeating a second charge eliminating step for removing charge on the surface of the electrophotographic photosensitive member,
An electrophotographic forming method, wherein the surface potential of the electrophotographic photosensitive member neutralized in the second static elimination step is higher than the potential of the surface of the electrophotographic photosensitive member neutralized in the first static elimination step.

  According to the electrophotographic method of the present invention, it is possible to solve both the improvement of the charging potential of the a-Si electrophotographic photosensitive member and the photo memory at the same time even if the speed of PS is increased.

The inventor found that it was difficult to solve both the improvement of the charging potential and the photo memory at the same time.
1. Making the difference in carrier density between the exposed area and the non-exposed area in the electrostatic latent image forming process uniform in the static elimination process; and
2. It was thought that this was because it was difficult to achieve both the reduction of excess carriers generated by static elimination light and the reduction of recombination with charged charges.

  Therefore, in order to continuously output a good image even in an ultra-high speed electrophotographic process, it was considered necessary to control carriers remaining in the photoconductor in the electrostatic latent image forming process and the charge eliminating process. .

  Therefore, a sub-charger and a second charge remover are provided between the charge remover and the charger (hereinafter referred to as a first charge remover and a main charger). With this configuration, it is possible to control the difference in carrier density between the exposed portion and the non-exposed portion when forming an electrostatic latent image by increasing the exposure amount of the first charge remover. Thereafter, an electric charge is supplied to the surface of the photoreceptor by the sub-charger, and the excess number of carriers in the electrophotographic photosensitive member is controlled by the combination of the excess carriers generated in the first charge removal process by the first charge remover and the surface charge. It can be carried out. Further, the surface of the photoconductor after the second static elimination process by the second static eliminator is neutralized so as to be higher than the potential of the surface of the electrophotographic photosensitive member after the first static elimination process by the first static eliminator. . As a result, it is possible to control again the difference in carrier density between the exposed portion and the non-exposed portion in the electrostatic latent image forming step, and to control excess carriers in the second static elimination step.

  By controlling the residual carrier in such a photoconductor, that is, by controlling the surface potential of the electrophotographic photoconductor, the charging potential can be improved even when image formation is performed by an electrophotographic apparatus at high speed and continuously. I found that photo memory could be improved.

The present invention comprises a main charging step of charging a surface of an electrophotographic photosensitive member having a photoconductive layer and a surface layer made of an amorphous material having silicon atoms as a base on a conductive substrate, and thereafter, electrophotographic photosensitive An electrostatic latent image forming step for forming an electrostatic latent image on the surface of the body, a developing step for developing the electrostatic latent image as a toner image, a transfer step for transferring the toner image to a recording medium, and then an electrostatic latent image. A first charge eliminating step to remove the image, and then
An electrophotographic forming method for forming an electrophotographic image by sequentially repeating a sub-charging step for charging the surface of the electrophotographic photosensitive member and a second static eliminating step for neutralizing the surface of the electrophotographic photosensitive member,
An electrophotographic forming method, wherein the surface potential of the electrophotographic photosensitive member neutralized in the second static elimination step is higher than the potential of the surface of the electrophotographic photosensitive member neutralized in the first static elimination step.

  Here, when the surface potential of the electrophotographic photosensitive member after the main charging step is V1 (V) and the surface potential of the electrophotographic photosensitive member after the sub-charging step is V2 (V), V2 / V1 is 0. It is preferable that it is 2 or more and 0.8 or less.

Furthermore, the potential difference V2-VL2 between the surface potential V2 (V) of the electrophotographic photosensitive member after the sub-charging step and the surface potential VL2 (V) of the electrophotographic photosensitive member after the second charge eliminating step, the electrophotography after the sub-charging step. Regarding the potential difference V2-VL1 between the surface potential V2 (V) of the photoreceptor and the surface potential VL1 (V) of the electrophotographic photoreceptor after the first static elimination step,
It is preferable that V2-VL2 is 70 V or more and 270 V or less, and V2-VL1 is 100 V or more and 300 V or less.

  Further, regarding the surface potential VL1 (V) of the electrophotographic photosensitive member after the first static elimination step and the surface potential VL2 (V) of the electrophotographic photosensitive member after the second static elimination step, VL2-VL1 is 10 V or more and 60 V or less. It is preferable that

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

(Electrophotographic equipment)
The configuration of an electrophotographic apparatus capable of high-speed output using an a-Si electrophotographic photosensitive member will be described with reference to a schematic diagram shown in FIG.

The electrophotographic apparatus is provided around the a-Si electrophotographic photosensitive member 101.
A main charger 102 for charging the electrophotographic photosensitive member 101 for forming an electrostatic latent image;
A developing device 114 for supplying developing toner to the electrophotographic photosensitive member 101 on which the electrostatic latent image is formed by the electrostatic latent image forming means 108;
A transfer charger 106 for transferring toner on the surface of the electrophotographic photosensitive member to a transfer material 112 serving as a recording medium such as paper;
A separation charger 107 for separating the transfer material 112 and the electrophotographic photosensitive member 101 after the toner is transferred to the transfer material 112;
A first static eliminator 104 for neutralizing the surface of the electrophotographic photosensitive member to erase the electrostatic latent image;
A sub-charger 103 that removes excess carriers generated in the first static eliminator 104;
A second static eliminator 105 that performs static erasure again to erase a photo memory that could not be erased by the first static eliminator 104;
A cleaner 111 for cleaning the surface of the electrophotographic photosensitive member is provided. Further, the separated transfer material 112 is sent by the conveying means 113.

  Further, a photoconductor heater (not shown) may be provided inside the electrophotographic photoconductor 101, and the electrophotographic photoconductor 101 can be heated by using this photoconductor heater. In FIG. 1, in order to uniformly clean the surface of the electrophotographic photosensitive member, the cleaning process of the surface of the electrophotographic photosensitive member is performed using the magnet roller 109 and the cleaning blade 110, but only one of them may be used.

  Image formation using such an electrophotographic apparatus is performed as follows, for example. First, a main charging process in which the surface of the electrophotographic photosensitive member 101 is uniformly charged using the main charger 102 by rotating the electrophotographic photosensitive member 101 in the direction of the arrow at a predetermined speed. Next, an electrostatic latent image forming step of forming an electrostatic latent image on the surface of the electrophotographic photosensitive member 101 by the electrostatic latent image forming unit 108 on the charged surface of the electrophotographic photosensitive member 101.

  The electrostatic latent image forming unit 108 exposes the surface of the electrophotographic photosensitive member 101 charged by the main charging device 102, generates a charge distribution on the surface of the electrophotographic photosensitive member 101, and forms an electrostatic latent image. It consists of an optical system.

  A developing process in which toner is supplied to the surface of the electrophotographic photosensitive member 101 by the developing device 114 when the electrostatic latent image portion formed on the surface of the electrophotographic photosensitive member 101 passes through the installation portion of the developing device 114; A developing process in which the electrostatic latent image is visualized (developed) as a toner image. Further, the toner image reaches the installation portion of the transfer charger 106 with the rotation of the electrophotographic photosensitive member 101, and is transferred to the transfer material 112 sent by the transport roller 113 here.

  After the transfer is completed, the transfer material 112 is separated from the electrophotographic photosensitive member 101 by the separation charger 107. The separation method may be performed by a mechanical method using a belt, a nail or the like. After the transfer material 112 is separated from the electrophotographic photosensitive member 101, since the residual potential remains in the electrophotographic photosensitive member 101, the charge is removed by the first static eliminator 104 so that the surface potential becomes zero or almost zero. 1st static elimination process. Then, the transfer residual toner on the surface of the electrophotographic photosensitive member 101 is removed by the cleaner 111. Thereafter, the surface of the electrophotographic photosensitive member 101 is charged by the sub-charger 103, and is sub-charged. The second charge eliminator 105 again removes the charge so that the surface potential is higher than that at the first charge eliminator 104. One copy process is completed through the second static elimination process.

  In the electrophotographic apparatus of the present invention, the arrangement of the main charger 102 and the sub charger 103, and the first charge remover 104 and the second charge remover 105 are arranged from the electrostatic latent image forming step to the electrophotographic photosensitive member rotating direction. On the downstream side, the main charger 102, the first charge remover 104, the sub-charger 103, and the second charge remover 105 are arranged in this order.

  This is because, for example, if the arrangement of the secondary charger 103 and the second static eliminator 105 is switched, the first static eliminator 104 and the second static eliminator 104 are charged before the secondary charger 103 charges the electrophotographic photosensitive member 101. A large amount of carriers are generated inside the electrophotographic photosensitive member when the electric charge is removed by the electric device 105. Even if the electrophotographic photosensitive member 101 is charged by the sub-charger 103 in such a state, the electrophotographic photosensitive member is rotated at a high speed, and thus occurs in the first and second static elimination steps between the sub-charging steps. There are cases where excess carriers cannot be erased. For this reason, in the main charging process, the surface potential of the electrophotographic photosensitive member may decrease during charging and after charging due to residual carriers that could not be erased in the sub charging process, and the surface potential at the position of the developing device may decrease. there were. In addition, since the surface potential may decrease drastically due to the residual carrier even after the sub-charging step, it becomes difficult to control the charging potential in the main charging step, and the surface potential at the developing unit is stabilized. May decrease.

Therefore, by disposing the main charger 102, the first charge remover 104, the sub-charger 103, and the second charge remover 105 in this order on the downstream side with respect to the electrophotographic photosensitive member rotation direction,
1. Even if the electrophotographic photosensitive member rotates at high speed, the generated carriers in the first static elimination process can be almost erased by the charge supplied to the surface of the electrophotographic photosensitive member in the sub-charging process.
2. Since the entire surface of the electrophotographic photosensitive member is again exposed and controlled to a predetermined surface potential in the second charge eliminating step, the main charging step can be stably controlled to the predetermined surface potential.

  The charging method used in the main charging process and the sub charging process may be any charging system such as corona charging or contact charging. When the corona charging method is used, either a corotron or a scorotron may be used, but it is preferable to use a scorotron because it is necessary to adjust to a predetermined potential in the main charging step. In the sub-charging process, it is preferable to use corotron when the surface potential is suddenly increased due to the influence of the first static elimination process, and scorotron from the viewpoint of stability of the surface potential when a low potential is acceptable.

  Further, the sub charger 103 is disposed between the first neutralizer 104 and the second neutralizer 105 and on the downstream side of the transfer charger 106 with respect to the electrophotographic photosensitive member rotation direction. It ’s fine. The first static eliminator 104 and the second static eliminator 105 neutralize the charge on the surface of the photoreceptor with light. As light, light output from a light emitting diode (LED), a semiconductor laser, a halogen lamp or the like is generally used.

  The first static eliminator 104 and the second static eliminator 105 need only be arranged in the order described above, but are arranged apart from the main charger 102 arranged on the downstream side with respect to the electrophotographic photosensitive member rotation direction. It is preferable. The reason is that, since the time from static elimination to charging becomes longer, the number of carriers recombined generated by static elimination light increases and the number of remaining carriers in the film decreases, so the influence on the charging potential during the charging process is reduced. Because. At the same time, since the time from static elimination to charging becomes longer, the probability that carriers are trapped in the defect level increases, so that the photo memory can be reduced.

  Further, the wavelength of the neutralizing light used in the first static eliminator 104 and the second static eliminator 105 may be approximately the same as the wavelength of the light used in the electrostatic latent image forming process. However, the wavelength of the static elimination light used in the first static elimination process is larger than the wavelength of the light used in the electrostatic latent image forming process, and the wavelength of the static elimination light used in the second static elimination process than the wavelength of the static elimination light used in the first static elimination process. Is more preferably a long wavelength. The reason for this is that, since the penetration distance into the film becomes longer when using a longer wavelength than when using static elimination light of the same wavelength, even if the exposure amount is reduced and the number of generated carriers in the film is small, the photo memory This is because improvement is possible. At the same time, since the number of carriers generated in the second static elimination step is reduced, it is possible to reduce the influence on the charging potential due to residual carriers that could not be recombined.

  Next, potential control of the electrophotographic photosensitive member will be described with reference to FIG. In FIG. 2, the horizontal axis represents time, and the vertical axis represents the surface potential of the electrophotographic photosensitive member. The potential immediately after the completion of the first static elimination process by the first static elimination device 104 is VL1, the potential immediately after the completion of the secondary electrification process by the secondary charger 103 is V2, and the potential immediately after the second static elimination process by the second static elimination device 105 is VL2. The potential immediately after the main charging process by the charger 102 is set to V1.

  The measuring method of V1, V2, VL1, and VL2 can be obtained by measuring the surface potential of the electrophotographic photosensitive member surface with a potential probe or the like. The potential after the main and sub charging steps is preferably measured at a position downstream of the electrophotographic photosensitive member rotation direction and not affected by the charger. Further, the potential after the first and second static elimination steps is preferably measured at a position downstream of the electrophotographic photosensitive member rotation direction and at a position where the surface potential immediately after the neutralization light irradiation can be measured.

  FIG. 2 shows the state of the surface potential of the electrophotographic photosensitive member for one cycle from the first static elimination step to the next first static elimination step. The surface potential of the electrophotographic photosensitive member becomes VL1 after the completion of the first static elimination process, and becomes V2 after the completion of the auxiliary charging process. Thereafter, the surface potential of the electrophotographic photosensitive member decreases and becomes VL2 after the second static elimination step. Thereafter, after completion of the main charging step, the surface of the electrophotographic photosensitive member is charged and the surface potential becomes V1. Thereafter, the surface potential of the electrophotographic photosensitive member gradually decreases, and the surface potential of the electrophotographic photosensitive member becomes VL1 in the next first charge eliminating step.

  The present invention is characterized in that the potential VL2 on the surface of the electrophotographic photosensitive member after static elimination in the second static elimination step is made higher than the potential VL1 on the surface of the electrophotographic photosensitive member after static elimination in the first static elimination step. The reason is shown below.

  One purpose of static elimination in the first static elimination step is to erase the electrostatic latent image formed in the electrostatic latent image formation step. Therefore, when the static elimination light used in the first static elimination step and the light used in the electrostatic latent image forming step have the same wavelength, the entire surface of the electrophotographic photosensitive member is stronger in the first static elimination step than the electrostatic latent image formation step. In order to improve the photo memory, it is necessary to generate a large amount of carriers in the film by exposing the substrate to reduce the difference in carrier density between the irradiated portion and the non-irradiated portion in the electrostatic latent image forming step. Therefore, the surface potential of the electrophotographic photosensitive member immediately after the first static elimination step is zero or almost zero, or a potential at which the surface potential does not change even when the amount of static elimination light increases. However, even if such strong exposure is performed in the first static elimination step, the number of carriers due to recombination due to the generated carriers in the first static elimination step is reduced, and the surface is supplied to the surface of the electrophotographic photosensitive member in the sub-charging step. The carriers generated in the first static elimination step can be erased by the coupling with the electric charge.

  However, since the second static elimination step is performed immediately before the main charging step, the surface potential of the electrophotographic photosensitive member after the main charging step is greatly affected by the generated carriers in the second static elimination step. That is, if the number of generated carriers in the second static elimination process is too large, the photoreceptor surface potential at the developing unit position is lowered. On the other hand, in the second static elimination process, since it is necessary to further erase the photo memory that could not be erased in the first static elimination process, exposure with a certain degree of strength is required.

  Therefore, in order to achieve both reduction of the influence on the surface potential of the electrophotographic photosensitive member after the main charging step and erasure of the photomemory, it is more immediately after the second discharging step than the electrophotographic photosensitive member surface potential VL1 immediately after the first discharging step. It is necessary to increase the potential VL2.

  From this point of view, the difference VL2-VL1 between the surface potential VL2 of the electrophotographic photosensitive member after the second static elimination step and the surface potential VL1 of the electrophotographic photosensitive member after the first static elimination step is 10V or more and 60V or less. Thus, it is more preferable to control the surface potential.

  Further, the ratio V2 / V1 between the surface potential V1 of the electrophotographic photosensitive member after the main charging step and the surface potential V2 of the electrophotographic photosensitive member after the sub-charging step is 0.20 or more and 0.80 or less. It is preferable to control the surface potential. The reason is shown below.

  When V2 / V1 is greater than 0.80, a high electric field is applied to the electrophotographic photosensitive member during and after the sub-charging process. Therefore, the carriers remaining without being recombined among the carriers generated in the first static elimination step are combined with the charges supplied to the surface of the electrophotographic photosensitive member in the sub-charging step, and can be erased. As a result, the surface potential after the main charging step does not decrease due to the influence of residual carriers in the first static elimination step. It becomes possible to make it a potential.

  However, when V2 / V1 is greater than 0.80, a large amount of charge exists on the surface of the electrophotographic photosensitive member after the sub-charging step. Therefore, in order to erase the photo memory in the second static elimination process, the charge on the surface of the electrophotographic photosensitive member is canceled, and further, the difference in carrier density between the exposed part and the non-exposed part in the electrostatic latent image forming process is determined. Since it is necessary to reduce the size, it is necessary to irradiate the electrophotographic photosensitive member with strong exposure in the second static elimination step. As a result, even if the photo memory can be erased, the carrier generated in the second static elimination process affects the surface potential after the main charging process, and the surface potential of the electrophotographic photosensitive member at the developing unit is lowered. It may be difficult to control the potential.

  When V2 / V1 is smaller than 0.20, there is little charge present on the surface of the electrophotographic photosensitive member after the sub-charging process, so the difference in carrier density between the exposed area and the non-exposed area in the electrostatic latent image forming process. It is possible to reduce the exposure amount in the second static elimination step necessary to reduce the size. Therefore, even if the PS becomes faster, it is possible to erase the photo memory while suppressing a decrease in the surface potential after the main charging process due to the influence of the generated carriers in the second charge eliminating process.

  However, when V2 / V1 is smaller than 0.20, among the carriers generated in the first static elimination process at the time of the sub-charging process and after the sub-charging process, the remaining carriers without recombination and in the film The electric field applied to the carriers trapped in the defect level is lowered. As a result, the moving speed of these carriers decreases, and the coupling probability with the carriers supplied in the sub-charging process decreases. Therefore, the carrier generated in the first static elimination process is combined with the charge supplied in the main charging process when a high electric field is applied during the main charging process and after the main charging process. May decrease. As a result, even if the photo memory can be erased, the carrier generated in the first static elimination process affects the surface potential after the main charging process, and the surface potential of the electrophotographic photosensitive member at the developing unit is lowered. It may be difficult to control the potential.

  Further, the surface potential is adjusted so that the difference V2-VL1 between the surface potential V2 of the electrophotographic photosensitive member after the sub-charging step and the surface potential VL1 of the electrophotographic photosensitive member after the first static elimination step is 100V or more and 300V or less. It is preferable to control. The reason is shown below.

  When V2-VL1 is smaller than 100V, as described above, among the carriers generated in the first static elimination process during and after the secondary charging process, the carriers remaining in the film without recombination and in the film The electric field applied to the carriers trapped in the defect level is lowered. As a result, the moving speed of these carriers decreases, and the coupling probability with the carriers supplied in the sub-charging process decreases. As a result, the carrier generated in the first charge removal process erases the charge supplied in the main charge process when a high electric field is applied during the main charge process and after the main charge process. The potential may decrease. On the contrary, when V2-VL1 is larger than 300V, as described above, a large amount of charge is present on the surface of the electrophotographic photosensitive member after the sub-charging process. It is necessary to increase the amount of static elimination light. As a result, even if the photo memory can be erased, the carrier generated in the second static elimination process affects the surface potential after the main charging process, and the surface potential of the electrophotographic photosensitive member at the developing unit is lowered. It may be difficult to control the potential.

  Further, the surface potential is set so that the difference V2-VL2 between the surface potential V2 of the electrophotographic photosensitive member after the sub-charging step and the surface potential VL2 of the electrophotographic photosensitive member after the second static elimination step is 70V or more and 270V or less. It is preferable to control. The reason is shown below.

  Even if V2-VL2 is smaller than 70V because V2 is low, or even if V2-VL2 is smaller than 70V because VL2 is high, the number of carriers generated in the second static elimination step Therefore, the influence on the surface potential after the main charging step can be reduced, and the surface potential of the electrophotographic photosensitive member at the position of the developing device can be more easily controlled to a desired potential. However, since the number of carriers generated in the second static elimination step is small, the difference in carrier density between the exposed portion and the non-exposed portion in the electrostatic latent image forming step may not be further reduced after the second static elimination step. Therefore, the photo memory after the first static elimination process may not be further improved even if the second static elimination process is performed.

  Conversely, even if V2-VL2 is greater than 270V because V2 is high, or even if V2-VL2 is greater than 270V because VL2 is low, it occurs in the second static elimination process. Since the number of carriers to be performed is large, the difference in carrier density between the exposed portion and the non-exposed portion in the electrostatic latent image forming step can be further reduced after the second static elimination step, and the photomemory is further improved. However, the carrier generated in the second static elimination step affects the surface potential after the main charging step, and the surface potential of the electrophotographic photosensitive member at the position of the developing device is lowered, so that it may be difficult to control to the desired potential. .

  For these reasons, the surface V so that the difference V2-VL2 between the surface potential V2 of the electrophotographic photosensitive member after the sub-charging step and the surface potential VL2 of the electrophotographic photosensitive member after the second static elimination step is 70 V or more and 270 V or less. It is preferable to control the potential.

(Amorphous silicon electrophotographic photosensitive member according to the present invention)
The present invention is characterized in that an electrophotographic photosensitive member having a photoconductive layer made of an amorphous material having at least silicon atoms as a base material on a substrate is used. FIG. 3 shows a schematic schematic cross-sectional view of an a-Si electrophotographic photosensitive member suitable for the present invention.

  The electrophotographic photosensitive member shown in FIG. 3A is made of amorphous silicon (hereinafter also referred to as a-Si: H, X) containing a hydrogen atom or a halogen atom as a constituent element on a cylindrical substrate 301. A photoconductive layer 302 is provided.

  The electrophotographic photosensitive member shown in FIG. 3B has a photoconductive layer 302 having a photoconductivity made of a-Si: H, X and a surface layer of amorphous silicon carbide or amorphous carbon on a cylindrical substrate 301. 303 is provided.

  The electrophotographic photosensitive member shown in FIG. 3C is composed of an amorphous silicon charge injection blocking layer 304 containing nitrogen atoms, oxygen atoms, and boron atoms on a cylindrical substrate 301, and a-Si: H, X. A photoconductive layer 302 having photoconductivity and a surface layer 303 of amorphous silicon carbide or amorphous carbon are provided. The interface between the photoconductive layer 302 and the surface layer 303 may be continuously changed to perform interface control that suppresses interface reflection.

  In the electrophotographic photoreceptor shown in FIG. 3D, a photoconductive layer 302 is provided on a cylindrical substrate 301. This photoconductive layer is composed of a charge generation layer 305 and a charge transport layer 306 made of a-Si: H, X, and an amorphous silicon carbide or amorphous carbon surface layer 303 is provided thereon. The interface between the charge generation layer 305 and the surface layer 303 may be continuously changed to perform interface control that suppresses interface reflection.

(Example)
EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further in detail, this invention is not restrict | limited at all by these.

(Electrophotographic photosensitive member production)
A cylindrical substrate made of aluminum (diameter 108 mm, length 358 mm) was mirror-finished with a diamond miracle bite to clean the surface of the cylindrical substrate. Next, using the plasma processing apparatus shown in FIG. 4, a charge injection blocking layer, a photoconductive layer, and a surface layer are formed in this order on the cleaned cylindrical substrate under the conditions shown in Table 1, and the positive charging a A -Si electrophotographic photosensitive member was produced. At this time, a high frequency power source capable of outputting high frequency power of 13.56 MHz was used.

(Evaluation equipment using electrophotographic equipment)
As an evaluation apparatus, a remodeled iR-8500 based on a Canon digital electrophotographic apparatus iR-8500 and modified so that normal image output is possible when the rotational speed of the electrophotographic photosensitive member is changed was used.

  As shown in the schematic diagram of FIG. 5, the structure of the iR-8500 remodeling machine is arranged around the a-Si electrophotographic photosensitive member 501 with respect to the rotation direction of the electrophotographic photosensitive member 501, 2 A static eliminator 505, a main charger 502, an electrostatic latent image means 508, a developing unit 514, a transfer charger 506, a separation charger 507, a first static eliminator 504, and a cleaner 511 are arranged in this order. Further, in order to measure the surface potential of the electrophotographic photosensitive member 501, a first potential sensor 515 is disposed downstream of the main charger 502, a third potential sensor 517 is disposed downstream of the first neutralizer 504, and the sub charger 503. The second potential sensor 516 is provided downstream of the second neutralizer 405, and the fourth potential sensor 518 is provided downstream of the second static eliminator 505.

  The cleaner 511 includes a magnet roller 509 and a cleaning blade 510. Further, the transfer charger 106 for transferring the toner on the surface of the electrophotographic photosensitive member to the transfer material 112 serving as a recording medium such as paper, and the transfer material 112 and the electrophotographic photosensitive member after the toner has transferred to the transfer material 112. A separation charger 107 for separating 101 is provided between the developing unit 514 and the first static eliminator 504.

  The transfer material 512 is conveyed by the conveying means 513.

  Here, as the main charger 502 and the sub charger 503 used in the main charging step, a single scorotron was used, and a high voltage power source was connected to the wire and grit of the main charger 502 and the sub charger 503, respectively. The main charger 502 and the sub charger 503 have a grit potential of 850 V, and control the current supplied to the charger wire to control the surface potential of the photoreceptor. The sub charger 503 is disposed at a position where the wire position of the sub charger 503 is 60 ° upstream from the wire position of the main charger 502 in the rotation direction of the electrophotographic photosensitive member.

  Further, an LED having a wavelength of 660 nm is used as a static elimination light source used in the first static eliminator 504, and the first static eliminator 504 is disposed at a position 125 ° from the wire of the main charger 502 on the upstream side in the rotation direction of the electrophotographic photosensitive member. Installed. The neutralization light source used in the second static eliminator 505 is also an LED having a wavelength of 660 nm, and the second static eliminator 505 is arranged at a position 30 ° from the wire of the main charger 502 on the upstream side in the rotation direction of the electrophotographic photosensitive member. installed. The first static eliminator 503 and the second static eliminator 504 were each connected to a DC power source, and the voltage applied to the LEDs was changed to change the amount of static elimination light.

  Further, the first potential sensor 515 for measuring the surface potential of the electrophotographic photosensitive member after the main charging step by the main charger 502 is connected to the main charger 502 from the wire of the main charger 502 on the downstream side in the rotation direction of the electrophotographic photosensitive member. It was installed at a position of 20 °. The second potential sensor 516 that measures the surface potential of the electrophotographic photosensitive member after the sub-charging step by the sub-charging device 503 is positioned 40 ° from the wire of the main charging device 502 on the upstream side in the rotation direction of the electrophotographic photosensitive member. Installed. Further, the third potential sensor 517 for measuring the surface potential of the electrophotographic photosensitive member after the first static elimination step by the first static eliminator 504 is 110 ° from the wire of the main charger 502 on the upstream side in the rotation direction of the electrophotographic photosensitive member. It is installed in the position. The fourth potential sensor 518 for measuring the surface potential of the electrophotographic photosensitive member after the second static eliminating step by the second static eliminator 505 is 20 ° from the wire of the main charger 502 upstream in the direction of rotation of the electrophotographic photosensitive member. It was installed in the position. Each potential sensor is connected to a surface potential meter (Model 344, manufactured by TREK), and the surface potential of the electrophotographic photosensitive member is measured.

(Example 1)
The electrophotographic photosensitive member produced in the electrophotographic photosensitive member production example was installed in an evaluation apparatus using an electrophotographic apparatus, and an image was output at PS of 700 mm / sec. With respect to the obtained image, the chargeability and the photomemory were evaluated by the chargeability evaluation method 1 and the photomemory evaluation method 1 described later. At this time, the evaluation results are shown in Table 2.

  The image output conditions of Example 1 are shown below. In the main charging process, the wire current in the main charging process was constant at 1300 μA. In the secondary charging process, the current supplied to the wire in the secondary charging process was controlled so that the surface potential of the electrophotographic photosensitive member after the secondary charging process was 200V.

  The charge removal light used in the first charge removal step was based on an energy of 2.5 μJ when iR-8500 and PS was 450 mm / sec. And according to PS, it adjusted so that the irradiation energy to the electrophotographic photoreceptor surface might become fixed.

  The semiconductor laser used in the latent image forming process is necessary to set the photoreceptor surface potential after the main charging process to 400 V when the PS is 450 mm / sec with iR-8500, and from 400 V to 50 V after the semiconductor laser irradiation. Based on energy. And according to PS, it adjusted so that the irradiation energy to the electrophotographic photoreceptor surface might become fixed.

  Furthermore, the charge removal light used in the second charge removal step is set to 400V on the surface potential of the electrophotographic photosensitive member after the main charging step when the PS is 450 mm / sec by the evaluation device, and the charge removal light energy used in the first charge removal step is After removing the charge at 2.5 μJ, the surface potential of the electrophotographic photosensitive member after the sub-charging process was set to 200 V, and the energy required to change from 200 V to 30 V after the discharge light used in the first discharging process was used as a reference. And according to PS, it adjusted so that the irradiation energy to the electrophotographic photoreceptor surface might become fixed.

(Comparative Example 1)
The electrophotographic photosensitive member produced in the electrophotographic photosensitive member production example is installed in the evaluation apparatus using the electrophotographic apparatus, and the charging in the sub-charging process is turned off and the light quantity of the static eliminating light in the second static eliminating process is turned off. An image was output under the conditions of Example 1. The obtained image was evaluated for chargeability and photomemory in the same manner as in Example 1. At this time, the evaluation results are shown in Table 2.

(Comparative Example 2)
The electrophotographic photosensitive member produced in the electrophotographic photosensitive member production example is installed in the evaluation apparatus using the electrophotographic apparatus, the amount of the static elimination light in the second static elimination step is turned off, and an image is output under the conditions of Example 1. The obtained images were evaluated for chargeability and photomemory in the same manner as in Example 1. At this time, the evaluation results are shown in Table 2.

(Comparative Example 3)
The electrophotographic photosensitive member produced in the electrophotographic photosensitive member production example is installed in the evaluation apparatus using the electrophotographic apparatus, the charging in the sub-charging process is turned off, and the amount of static elimination light in the second static elimination process is the same as in Example 1. An image was output under the conditions of Example 1 in accordance with the applied voltage to the used LED. The obtained image was evaluated for chargeability and photomemory in the same manner as in Example 1. The evaluation results at this time are shown in Table 2.

(Charging evaluation method 1)
An image to be evaluated was obtained by using an image output by setting the evaluation apparatus in an environment of 23 ° C. and 45% and turning off the photosensitive member heater.

  The test chart used for the evaluation of the chargeability was an A3 black chart having a reflection density of 1.1 on the entire surface, and was carried out by the following method.

A test chart was placed on the platen and the image density of the copy image obtained when copying was measured. The measurement position was near the center of the A3 copy image, and the reflection density was measured five times to obtain an average value. From the average value of the reflection density obtained from the image output under each condition, the ratio to condition 1 was obtained and compared. The image density was measured using an image densitometer (MacbethRD914). The evaluation criteria are as follows, and the evaluation target was the average value of the reflection density obtained from the image when PS was 450 mm / sec under the evaluation apparatus conditions using the electrophotographic apparatus of Comparative Example 1.
A. The ratio to the reflection density obtained from an image output at PS 450 mm / sec under the conditions of the evaluation apparatus using the electrophotographic apparatus of Comparative Example 1 is very good at 1.0 or more.
○ The ratio to the reflection density obtained from the image output at PS 450 mm / sec under the conditions of the evaluation apparatus using the electrophotographic apparatus of Comparative Example 1 is 0.9 or more and less than 1.0.
Δ: The ratio to the reflection density obtained from the image output at PS 450 mm / sec under the conditions of the evaluation apparatus using the electrophotographic apparatus of Comparative Example 1 is 0.8 or more and less than 0.9, and there is no practical problem.
X: The density difference can be visually confirmed since the ratio to the reflection density obtained from the image output at PS 450 mm / sec under the conditions of the evaluation apparatus using the electrophotographic apparatus of Comparative Example 1 is less than 0.8.

(Photo memory evaluation method 1)
An image to be evaluated was obtained by using an image output by setting the evaluation apparatus in an environment of 23 ° C. and 45% and turning off the photosensitive member heater.

  The test chart used for the evaluation of the photo memory is a halftone having a reflection density of 0.8 as shown in FIG. 6 and a reflection density of 1.1 mm having a width of 20 mm and a short side at one position 20 mm from the right end of the long side. Evaluation was performed by the following method using a test chart of A3 having a black line.

  The test chart was placed on the platen with the black line side as the leading edge of the document, and the image density of the copy image obtained when copying was measured. The measurement position is the center position a of the copy image corresponding to the longitudinal direction of the electrophotographic photosensitive member in the A3 copy image, and the positions b and 340 mm apart from the central portion of the black line portion by 300 mm in the rotation direction of the electrophotographic photosensitive member. The measured position c was measured. The measured ratio of the reflection density at the 300 mm position to the reflection density at the 340 mm position was determined and compared. The image density was measured using an image densitometer (MacbethRD914). The evaluation criteria are as follows.

  A: The ratio of the reflection density at the 300 mm position to the reflection density at the 340 mm position is 1.0 to less than 1.05, which is very good.

  ○: The ratio of the reflection density at the 300 mm position to the reflection density at the 340 mm position is 1.05 or more and less than 1.10.

  Δ: The ratio of the reflection density at the 300 mm position to the reflection density at the 340 mm position is 1.10 or more and less than 1.15, and there is no practical problem.

  X: The ratio of the reflection density at the 300 mm position to the reflection density at the 340 mm position is 1.15 or more, and the density difference can be visually confirmed.

  From the results shown in Table 2, when PS is accelerated in the configuration of Comparative Example 1 which is a conventional electrophotographic process, the image density is lowered due to a decrease in charging potential, and the ratio of the reflection density is large in the evaluation of the image density unevenness by the photo memory. became. In addition, when the charging process was performed at two places as in Comparative Example 2, the charging potential was satisfactory because the charging potential could be sufficiently secured even when the PS speeded up, but in the evaluation of the image density unevenness by the photo memory, it was reflected. The concentration ratio increased. On the contrary, when there are two static elimination steps as in Comparative Example 3, the image density unevenness due to the photo memory is good because sufficient static elimination is performed even if the PS becomes faster. The image density has decreased. However, when the electrophotographic process of the present invention is used, the charging potential is sufficiently secured even if the PS is accelerated, so that the charging property is good, and since sufficient static elimination is performed, the image density unevenness due to the photo memory is also good. there were.

(Example 2)
The electrophotographic photosensitive member produced in the electrophotographic photosensitive member production example is installed in an evaluation apparatus using an electrophotographic apparatus, and the current supplied to the charger wire in the sub-charging process is controlled so that the conditions shown in Table 3 are satisfied. Was output. For the obtained image, the chargeability was evaluated by the chargeability evaluation method 2 described later, and the photomemory was evaluated in the same manner as in Example 1. At this time, the evaluation results are shown in Table 5. Further, the surface potential (V1, V2, VL1, VL2) measured by the first to fourth potential sensors, the measurement results of V2 / V1, V2-VL2, V2-VL1, VL2-VL1, and the charging wire in the main charging step Table 4 shows the amount of current I1 (μA) supplied to.

  The image output conditions of Example 2 are shown below. In all image output conditions, PS was fixed at 700 mm / sec. The first static elimination step was adjusted based on the criteria of Example 1. In the second static elimination step, the voltage applied to the LED was adjusted so that the potential after the second static elimination step was 30 V under each condition in Table 3.

(Chargeability evaluation method 2)
The chargeability in the electrophotographic process was evaluated by the amount of current supplied to the charging wire necessary for charging in the main charging process. The evaluation criteria are as follows.
○ …… The charging current required for charging in the main charging process is very good at 1400μA or less.
Δ: The charging current required for charging in the main charging process is 1400 μA to 1600 μA or less, and there is no practical problem.
X: A charging current larger than 1600 μA is required in the main charging step, and power consumption in charging is too large.

  From Table 4, when the charging potential V2 in the sub-charging process was changed, the power consumption in the main charging process and the image density unevenness due to the photo memory were good even under the fast PS condition. However, when V2 / V1 is set to 0.2 or more and 0.8 or less, the image density unevenness due to the photo memory is improved. Furthermore, when V2-VL2 is 70 V or more and 270 V or less and V2-VL1 is 100 V or more and 300 V or less, both power consumption in the main charging step and image density unevenness due to the photo memory are the best.

(Example 3)
The electrophotographic photosensitive member produced in the electrophotographic photosensitive member production example is installed in an evaluation apparatus using an electrophotographic apparatus, and an image is obtained by adjusting the voltage applied to the LED in the second static elimination process so that the conditions shown in Table 5 are satisfied. The chargeability and photomemory were evaluated in the same manner as in Example 2 for the output image. At this time, the evaluation results are shown in Table 7. Further, the surface potential (V1, V2, VL1, VL2) measured by the first to fourth potential sensors, the measurement results of V2 / V1, V2-VL2, V2-VL1, VL2-VL1, and the charging wire in the main charging step Table 7 shows the amount of current I1 (μA) supplied to.

  The image output conditions of Example 3 are shown below. In all image output conditions, PS is constant at 700 mm / sec. In the sub-charging process, the current supplied to the charger wire in the sub-charging process is controlled so that the potential after the sub-charging process is 150 V, and the first charge eliminating process is adjusted based on the criteria of Example 1. It was.

(Comparative Example 4)
Except for the conditions shown in Table 6, the chargeability and photomemory of the image obtained by outputting the image in the same manner as in Example 3 were evaluated in the same manner as in Example 2. At this time, the evaluation results are shown in Table 7.

  From Table 7, when the surface potential VL2 after the second static elimination process is changed, even if PS is fast, if VL1 <VL2, the power consumption in the main charging process and the image density unevenness due to the photo memory are It was good. Further, when V2-VL2 is set to 70 V or more, the image density unevenness due to the photo memory is improved, and when VL2-VL1 is set to 10 V or more and 60 V or less, the power consumption in the main charging process and the image density unevenness due to the photo memory are the most. It became good.

It is a typical schematic explanatory drawing of the electrophotographic process using the a-Si electrophotographic photoreceptor concerning this invention. It is explanatory drawing of the electric potential control performed by the electrophotographic process using the a-Si electrophotographic photoreceptor concerning this invention. 1 is a schematic cross-sectional view schematically showing a layer configuration of an a-Si electrophotographic photosensitive member according to the present invention. It is a typical schematic block diagram which shows an example of the a-Si electrophotographic photoreceptor manufacturing apparatus by the high frequency plasma CVD method using RF band. It is a typical schematic explanatory drawing of the electrophotographic process using the a-Si electrophotographic photosensitive member used in the Example. It is an evaluation chart of the image density nonuniformity used in the Example. It is a typical schematic explanatory drawing of the electrophotographic process using the conventional electrophotographic photoreceptor.

Explanation of symbols

101, 501, 701 a-Si electrophotographic photosensitive member 102, 502, 702 Main charger 103, 503 Sub-charger 104, 504, 704 First charge remover 105, 505 Second charge remover 106, 506, 706 Transfer charger 107, 507, 707 Separation charger 108, 508, 708 Electrostatic latent image means 109, 509, 709 Magnet roller 110, 510, 710 Cleaning blade 111, 511, 711 Cleaner 112, 512, 712 Transfer material 113, 513, 713 Conveying means 114, 514, 714 Developer 300 Electrophotographic photosensitive member 301 Cylindrical substrate 302 Photoconductive layer 303 Surface layer 304 Charge injection blocking layer 305 Charge generation layer 306 Charge transport layer 401 Cylindrical substrate 402 Reaction vessel 403 Source gas introduction tube 404 Heater 40 Substrate holding member 406 cap 407 matching box 408 high-frequency power source 515 first potential sensor 516 second potential sensor 517 third potential sensor 518 fourth potential sensor

Claims (4)

A main charging step of charging the surface of the electrophotographic photosensitive member having a photoconductive layer and a surface layer made of an amorphous material having silicon atoms as a base on a conductive substrate, and then the surface of the electrophotographic photosensitive member An electrostatic latent image forming step for forming an electrostatic latent image on the surface, a developing step for developing the electrostatic latent image as a toner image, a transfer step for transferring the toner image to a recording medium, and then the electrostatic latent image. A first charge eliminating step for discharging the image, and then a sub-charging step for charging the surface of the electrophotographic photosensitive member;
A method of forming an electrophotographic method of forming an electrophotography by sequentially repeating a second charge eliminating step for removing charge on the surface of the electrophotographic photosensitive member,
A method of forming an electrophotographic image, wherein a surface potential of the electrophotographic photosensitive member neutralized in the second neutralizing step is higher than a potential of the surface of the electrophotographic photosensitive member neutralized in the first neutralizing step. . When the surface potential of the electrophotographic photosensitive member after the second static elimination step is VL2 (V) and the surface potential of the electrophotographic photosensitive member after the first static elimination step is VL1 (V),
2. The method of forming an electrophotographic image according to claim 1, wherein V2-VL2 is 70 V or more and 270 V or less, and V2-VL1 is 100 V or more and 300 V or less.   The method of forming an electrophotographic image according to claim 2, wherein VL2-VL1 is 10 V or more and 60 V or less.   When the surface potential of the electrophotographic photosensitive member after the main charging step is V1 (V) and the surface potential of the electrophotographic photosensitive member after the sub charging step is V2 (V), V2 / V1 is 0. 2. The method for forming an electrophotographic image according to claim 1, wherein the method is 2 or more and 0.8 or less.

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