JP4295486B2 - Electrophotographic image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electrophotographic image forming apparatus.
[0002]
[Prior art]
In a charging device used in an electrophotographic image forming apparatus, discharge products such as ozone and NOx are generated in the discharge region, and this reacts with moisture to cause damage such as image flow to the photoreceptor. It is required to quickly discharge discharge products from the discharge region and to maintain the environment of the discharge region at low humidity.
[0003]
As a discharge means for discharging discharge products from the discharge region, forced discharge by airflow generation is generally performed, and in a charger that uses corona discharge of a wire, a method of flowing an airflow in the longitudinal direction of the casing is adopted. It has been.
[0004]
However, when a contact type or non-contact type charging roller is used, it is not easy to adopt the same method. This is because, as shown in FIG. 13, the charging roller 100 is long corresponding to the charging width, and the proximity portion between the charging roller 100 and the photosensitive member 101, which is a discharge region, is generally as narrow as several tens to several hundred μm. Even if air is flowed in the longitudinal direction along the discharge region, the pressure loss of the flow path is very large, so that it is very difficult to form and discharge a uniform air flow in the longitudinal direction. Although it is conceivable to enclose the charging roller 100 with the case 102 and flow air in the longitudinal direction with respect to the upper space in the case 102, in this case, it is not always possible to replace the air in the discharge region, A large flow rate is required with respect to the amount of air in the discharge region that is originally required to be removed, which is wasteful. There is also known an image forming apparatus in which air is blown toward a contact portion between a charging roller and a photoreceptor (see Patent Document 1 and Patent Document 2).
[0005]
Here, as the air supplied into the case 102, an inert gas that does not easily generate NOx or ozone by discharge, or low-humidity air that can suppress chemical change of the generated NOx to ammonium nitrate that easily adheres to the photoreceptor 101 is used. As a result, damage to the photoreceptor 101 is reduced.
[0006]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 8-152764
[Patent Document 2]
JP-A-8-202126
[0007]
[Problems to be solved by the invention]
However, as described above, the control gas, such as an inert gas or low-humidity air, can be introduced into the discharge region in the vicinity of the charging roller 100 and the photoreceptor 101 only by flowing a control gas such as inert gas or low-humidity air through the case 102. It is difficult, and it is difficult to reduce the damage of the intended photoreceptor 101.
[0008]
An object of the present invention is to reliably introduce a control gas to a discharge region that is a proximity portion between a charging roller and a photosensitive member, to suppress the generation of a discharge product and to quickly discharge the generated discharge product from the discharge region. In other words, it is intended to extend the life of the photoreceptor by reducing damage to the photoreceptor due to the discharge products.
[0009]
[Means for Solving the Problems]
  In the first aspect of the present invention, an electrostatic latent image is formed by exposing the outer peripheral surface of a charged photosensitive member, and toner is supplied to the photosensitive member on which the electrostatic latent image has been formed to form a toner image. An electrophotographic image forming apparatus for transferring a formed toner image to a recording medium; a charging roller which is disposed in contact with the outer peripheral surface of the photoconductor in a non-contact manner and rotates in a rotating direction with respect to the photoconductor; A case that surrounds a part of the outer peripheral portion of the charging roller on the upstream side of the position facing the charging roller along the rotation direction of the photosensitive member including the position facing the charging roller on the outer peripheral surface of the photosensitive member; The airflow of the surface layer of the charging roller is prevented from entering the case from the downstream side of the position facing the photoconductor along the rotation direction of the charging roller, and the outflow of gas from the case to the outside of the case Allow An airflow blocking member arranged in a row, a control gas supply part for supplying a control gas, a control gas formed in the case in communication with the control gas supply part, and the control gas supplied from the control gas supply part in the case And an inflow port for substantially evenly flowing along the longitudinal direction of the photoreceptor.The
[0010]
In the present invention and each of the following inventions, “control gas” refers to various kinds of inert gas and the like controlled so as to suppress the generation of discharge products such as NOx and ozone that cause deterioration of the photoreceptor. It means low-humidity air or the like that can suppress gas and the generated NOx from chemically changing to ammonium nitrate that causes image flow of the photoreceptor. By supplying this control gas to the discharge region of the photoconductor, the generation of discharge products accompanying discharge and the chemical change of the generated NOx to ammonium nitrate, etc. are suppressed, and the photoconductor is caused by the discharge products, ammonium nitrate, etc. Is prevented, and the durability of the photoreceptor is improved.
[0011]
In the present invention and each of the following inventions, the “control gas supply unit” means means for generating the control gas described above and means for storing the control gas so as to be supplied.
[0012]
Therefore, when the control gas supplied from the control gas supply unit flows into the case from the inflow port, a part of the control gas flows as a surface layer airflow of the charging roller along the rotation direction of the charging roller. It is introduced into a discharge area which is an area close to the photoreceptor. This suppresses the generation of discharge products and ammonium nitrate (hereinafter referred to as discharge products) from the discharge products in the discharge region in the case, preventing deterioration of the photoconductor and improving the durability of the photoconductor. To do.
[0013]
Further, since the surface airflow of the charging roller is generated in the same manner in the entire area in the longitudinal direction of the charging roller, the generation of discharge products and the like is suppressed in the entire area in the longitudinal direction of the photoreceptor.
[0014]
Part of the control gas introduced up to the discharge area in the case passes through the gap between the photoconductor and the charging roller, and rotates the photoconductor from the position where the charging roller and photoconductor face the outer peripheral surface of the photoconductor. It is introduced into a discharge region on the downstream side along the direction, that is, a discharge region located outside the case. As a result, the generation of discharge products and the like is suppressed even in the discharge region outside the case, and further deterioration prevention and durability improvement of the photoreceptor can be achieved.
[0015]
Part of the control gas that has passed through the gap between the photoconductor and the charging roller becomes a surface airflow of the charging roller and flows along the rotation direction of the charging roller. Entering the case is prevented. For this reason, even when the discharge gas or the like is contained in the control gas flowing outside the case as the surface airflow of the charging roller after passing through the discharge region, the discharge product or the like enters the case. It is prevented.
[0016]
A part of the control gas introduced up to the discharge region in the case and not entering the gap between the photosensitive member and the charging roller returns from the discharge region and swirls in the upstream space 22. Later, it merges with a portion of the low-humidity air that has flowed into the case and has not been introduced into the discharge region within the case, and flows out of the case from the location of the airflow blocking member.
[0017]
In this way, the control gas that has flowed into the case is sequentially exhausted out of the case, so that no discharge product or the like remains in the case.
[0018]
  According to a second aspect of the present invention, an outer peripheral surface of a charged photoreceptor is exposed to form an electrostatic latent image, and toner is supplied to the photoreceptor on which the electrostatic latent image is formed to form a toner image. An electrophotographic image forming apparatus for transferring a formed toner image to a recording medium; a charging roller which is disposed in contact with the outer peripheral surface of the photoconductor in a non-contact manner and rotates in a rotating direction with respect to the photoconductor; A case that surrounds the upstream and downstream sides of the position facing the charging roller along the rotation direction of the photoconductor including the position facing the charging roller on the outer peripheral surface of the photoconductor and the entire charging roller; The surface layer airflow of the charging roller from the downstream space that is downstream of the position facing the charging roller along the rotation direction of the photoconductor in the case with the charging roller along the rotation direction of the photoconductor Upstream of facing position An airflow blocking member disposed in the case so as to prevent the gas from flowing into the upstream space and to prevent the gas from flowing from the upstream space to the downstream space, and a control gas for supplying a control gas A longitudinal direction of the photosensitive member is formed in the case so as to communicate the supply unit, the control gas supply unit, and the upstream space, and the control gas supplied from the control gas supply unit is placed in the upstream space. And an exhaust port formed in the case so as to communicate with the downstream space.The
[0019]
Therefore, the control gas supplied from the control gas supply unit flows into the upstream space in the case from the inflow port, and a part of the control gas flows as the surface layer airflow of the charging roller along the rotation direction of the charging roller. The charging roller and the photosensitive member are introduced into a discharge area, which is an adjacent area. As a result, the generation of discharge products or the like in the discharge region in the upstream space is suppressed, the deterioration of the photoreceptor is prevented, and the durability of the photoreceptor is improved.
[0020]
Further, since the surface airflow of the charging roller is generated in the same manner in the entire area in the longitudinal direction of the charging roller, the generation of discharge products and the like is suppressed in the entire area in the longitudinal direction of the photoreceptor.
[0021]
Part of the control gas introduced to the discharge area in the upstream space passes through the gap between the photoconductor and the charging roller and is introduced into the discharge area in the downstream space in the case. As a result, the generation of discharge products and the like is suppressed even in the discharge region in the downstream space, and further deterioration prevention and durability improvement of the photoreceptor can be achieved.
[0022]
A part of the control gas in the downstream space that has passed through the gap between the photoconductor and the charging roller becomes a surface airflow of the charging roller and flows along the rotation direction of the charging roller. The airflow preventing member is prevented from entering the upstream space. For this reason, even if the discharge gas or the like is contained in the control gas that flows in the downstream space after passing through the discharge area and becomes the surface airflow of the charging roller, the discharge product or the like is upstream. It is prevented from entering the space.
[0023]
A part of the control gas introduced up to the discharge area in the upstream space and not entering the gap between the photosensitive member and the charging roller returns from the discharge area and swirls in the upstream space. After that, it merges with the low-humidity air that is part of the control gas that has flowed into the upstream space and has not been introduced into the discharge region, and flows out from the location of the airflow blocking member into the downstream space.
[0024]
All of the control gas that has flowed into the upstream space sequentially flows into the downstream space and is further exhausted from the exhaust port to the outside of the downstream space, so that discharge products into the upstream space and the downstream space are discharged. Etc. does not occur.
[0025]
The control gas that has flowed into the downstream space is exhausted out of the case through the exhaust port. Since the exhaust of the control gas from the downstream space is concentrated from the exhaust port, the discharge gas contained in the exhausted control gas is removed, and the control gas is circulated and reused. Becomes easier.
[0026]
  According to a third aspect of the invention, an electrostatic latent image is formed by exposing the outer peripheral surface of a charged photosensitive member, and toner is supplied to the photosensitive member on which the electrostatic latent image has been formed to form a toner image. An electrophotographic image forming apparatus for transferring the formed toner image to a recording medium; a contact charging roller disposed in contact with the outer peripheral surface of the photoconductor and rotating in a rotating direction with respect to the photoconductor; A case that surrounds the upstream and downstream sides of the contact position with the contact charging roller along the rotation direction of the photoreceptor including the contact position of the contact charging roller on the outer peripheral surface of the photoreceptor and the entire contact charging roller. And the charging along the rotation direction of the photoconductor from the downstream space downstream of the contact position with the charging roller along the rotation direction of the photoconductor in the case. With Laura An airflow blocking member disposed in the case so as to prevent entry into the upstream space that is upstream of the touch position and to allow gas outflow from the upstream space to the downstream space; and a control gas A control gas supply unit for supplying the control gas, the control gas supply unit and the upstream space are formed in the case so as to communicate with each other, and the control gas supplied from the control gas supply unit is placed in the upstream space. An inflow port that flows substantially evenly along the longitudinal direction of the photoreceptor, an exhaust port formed in the case in communication with the downstream space, and an external gas are allowed to enter the downstream space. A second inlet formed between the lower edge of the case and the outer peripheral surface of the photoconductor with a gap.The
[0027]
In the present invention and each of the following inventions, “gas from outside” is a concept including ambient air, and further includes a control gas supplied from a control gas supply unit.
[0028]
Therefore, the control gas supplied from the control gas supply unit flows into the upstream space in the case from the inflow port, and a part of the control gas becomes a surface airflow of the contact charging roller along the rotation direction of the contact charging roller. Then, the contact charging roller and the photosensitive member are introduced into a discharge area, which is an adjacent area. As a result, the generation of discharge products or the like in the discharge region in the upstream space is suppressed, the deterioration of the photoreceptor is prevented, and the durability of the photoreceptor is improved.
[0029]
Further, since the surface layer airflow of the contact charging roller is generated in the same manner in the entire area in the longitudinal direction of the contact charging roller, the generation of discharge products and the like is suppressed in the entire area in the longitudinal direction of the photoreceptor.
[0030]
The control gas introduced up to the discharge region in the upstream space is part of the control gas that has flowed into the upstream space after returning from the discharge region and swirling in the upstream space, and is introduced into the discharge region. It merges with the low-humidity air that did not exist, and flows out from the location of the airflow prevention member into the downstream space.
[0031]
On the other hand, a gas from the outside flows into the downstream space from the second inlet, and this gas is introduced into the discharge region in the downstream space, and then a part of the gas becomes a surface airflow of the contact charging roller. And flows along the rotation direction of the contact charging roller in the downstream space. However, the surface airflow is prevented from entering the upstream space by the airflow prevention member. For this reason, after being introduced into the discharge area in the downstream space, the discharge product contained in the gas flowing in the downstream space as the surface airflow of the charging roller is prevented from entering the upstream space. The
[0032]
The control gas that has flowed into the downstream space and the external gas that has flowed into the downstream space from the second inflow port are exhausted out of the case through the exhaust port.
[0033]
  In addition, the control gas supplied from a control gas supply part can also be used as gas from the outside which flows in into downstream space from a 2nd inflow port. In this case, a flow path that guides the control gas from the control gas supply unit to the second inflow port is formed. Thereby, generation | occurrence | production of the discharge product etc. in the discharge area | region in downstream space can be suppressed similarly to the discharge area | region in upstream space.
In the first to third aspects of the present invention, a counter roller that is disposed close to and parallel to the charging roller and rotates counter to the charging roller is provided as the airflow prevention member.
Therefore, the surface airflow of the counter roller collides with the surface airflow of the charging roller, and the collision prevents the surface airflow of the charging roller from entering the space in the case or the upstream space.
[0034]
According to a fourth aspect of the present invention, in the electrophotographic image forming apparatus according to any one of the first to third aspects, the photosensitive portion is formed on an edge of the case facing the upstream side in the rotation direction of the photosensitive member. A flexible contact member that is in sliding contact with the outer peripheral surface of the body is provided.
[0035]
Therefore, the surface airflow of the photoconductor can be peeled off from the outer peripheral surface of the photoconductor by the flexible contact member, the surface airflow of the photoconductor can be prevented from entering the case, and the filling of the control gas into the case is improved It is possible to improve the performance of suppressing the generation of discharge products and the like in the discharge region.
[0038]
  Claim5The described invention is claimed.Any one of 1 to 4In the electrophotographic image forming apparatus described above, the outer peripheral surface of the counter roller is textured.
[0039]
Accordingly, since the amount of the surface airflow of the counter roller is increased by the surface processing, the surface airflow of the charging roller is more effectively prevented from entering the space in the case or the upstream space.
[0040]
  Claim6The described invention is claimed.Any one of 1 to 5In the electrophotographic image forming apparatus described above, the diameter of the counter roller is smaller than the diameter of the charging roller.
[0041]
Accordingly, since the surface airflow of the counter roller acutely collides with the surface airflow of the charging roller, the surface airflow of the counter roller bites into the surface airflow of the charging roller. It is more effectively prevented from entering the upstream space.
[0042]
  Claim7The described invention is claimed.Any one of 1 to 4The electrophotographic image forming apparatus described above is characterized in that a brush is planted on the outer peripheral surface of the counter roller.
[0043]
Therefore, since the amount of the surface airflow of the counter roller is increased by the flocking of the brush, the surface airflow of the charging roller is more effectively prevented from entering the space in the case or the upstream space.
[0044]
  Claim8The invention described isThe outer peripheral surface of the charged photoconductor is exposed to form an electrostatic latent image, toner is supplied to the photoconductor on which the electrostatic latent image has been formed to form a toner image, and the formed toner image is recorded. In an electrophotographic image forming apparatus that transfers to a medium, a charging roller that is disposed so as to face the outer peripheral surface of the photoconductor in a non-contact manner and rotates in a rotating direction with respect to the photoconductor, and an outer peripheral surface of the photoconductor The upstream and downstream sides of the position facing the charging roller along the rotation direction of the photoconductor including the position facing the charging roller and the case surrounding the entire charging roller, and the surface airflow of the charging roller In the case, from the downstream space that is downstream of the position facing the charging roller along the rotation direction of the photoconductor, the upstream that is upstream of the position facing the charging roller along the rotation direction of the photoconductor Enter the side space An airflow blocking member disposed in the case so as to prevent gas from flowing into the downstream space from the upstream space, a control gas supply unit for supplying control gas, and the control A control gas is formed in the case so as to communicate the gas supply unit and the upstream space, and the control gas supplied from the control gas supply unit is substantially evenly distributed in the upstream space along the longitudinal direction of the photoconductor. An inflow port for inflow, and an exhaust port formed in the case in communication with the downstream space.
Accordingly, the same function as that of the common constituent elements of the invention described in claim 2 is obtained.
According to the ninth aspect of the present invention, an electrostatic latent image is formed by exposing the outer peripheral surface of a charged photosensitive member, and toner is supplied to the photosensitive member on which the electrostatic latent image is formed to form a toner image. An electrophotographic image forming apparatus for transferring the formed toner image to a recording medium; a contact charging roller disposed in contact with the outer peripheral surface of the photoconductor and rotating in a rotating direction with respect to the photoconductor; A case that surrounds the upstream and downstream sides of the contact position with the contact charging roller along the rotation direction of the photoreceptor including the contact position of the contact charging roller on the outer peripheral surface of the photoreceptor and the entire contact charging roller. And the charging along the rotation direction of the photoconductor from the downstream space downstream of the contact position with the charging roller along the rotation direction of the photoconductor in the case. With Laura An airflow blocking member disposed in the case so as to prevent entry into the upstream space that is upstream of the touch position and to allow gas outflow from the upstream space to the downstream space; and a control gas A control gas supply unit for supplying the control gas, the control gas supply unit and the upstream space are formed in the case so as to communicate with each other, and the control gas supplied from the control gas supply unit is placed in the upstream space. An inflow port that flows substantially evenly along the longitudinal direction of the photoreceptor, an exhaust port formed in the case in communication with the downstream space, and an external gas are allowed to enter the downstream space. And a second inlet formed between the lower end side edge of the case and the outer peripheral surface of the photoconductor with a gap.
Accordingly, the same function as that of the common constituent elements of the invention of claim 3 is exhibited.
The inventions of claims 8 and 9As the airflow prevention member, one end is close to the outer peripheral surface of the charging roller and the other end is opposed to the exhaust port.Multiple platesElementSo as to form a flow path between adjacent plate membersProvidedThe
[0045]
  Therefore, the surface airflow of the charging roller is plate-shapedElementPlate-like toward the exhaust port, which is peeled off from the charging roller by the vortex generated by pressure fluctuation before and afterElementThe surface airflow of the charging roller is prevented from entering the upstream space.
[0046]
ThisPlate shapeThe component isnumber,To form a flow path between adjacent plate membersBy providing, the effect of preventing the surface airflow of the charging roller from entering the upstream space is enhanced.
[0047]
According to a tenth aspect of the present invention, an electrostatic latent image is formed by exposing the outer peripheral surface of a charged photosensitive member, and toner is supplied to the photosensitive member on which the electrostatic latent image has been formed to form a toner image. An electrophotographic image forming apparatus for transferring a formed toner image to a recording medium; a charging roller which is disposed in contact with the outer peripheral surface of the photoconductor in a non-contact manner and rotates in a rotating direction with respect to the photoconductor; The outer circumferential surface of the charging roller is covered with a gap of a predetermined dimension along which the surface airflow flows along the outer circumferential surface of the photoconductor, and is more along the rotation direction of the photoconductor than the facing position between the photoconductor and the charging roller. A case in which an exhaust passage that is located near the upstream side and extends away from the photoconductor is formed, a control gas supply unit that supplies a control gas, and a control gas that is supplied from the control gas supply unit Along the outer peripheral surface of the photoreceptor And having a guide portion for guiding toward the opposite positions of the photosensitive member as a surface layer air current and the charging roller.
[0048]
Therefore, the control gas supplied from the control gas supply unit is guided to the guide unit and becomes a surface layer airflow of the photoconductor, and flows toward the position where the photoconductor and the charging roller face each other. And flows through a gap between the photosensitive member and the charging roller. As a result, the control gas is introduced into the upstream and downstream discharge areas along the rotation direction of the photoconductor relative to the position where the charging roller and the photoconductor face each other, and discharge products and the like are generated in the discharge area. This suppresses the deterioration of the photoconductor and increases the durability of the photoconductor.
[0049]
Further, since the surface airflow of the photoconductor is generated in the same manner in the entire area in the longitudinal direction of the photoconductor, the generation of discharge products and the like is suppressed in the entire area in the longitudinal direction of the photoconductor.
[0050]
The control gas that has passed through the gap between the photoconductor and the charging roller then becomes a surface airflow of the charging roller and flows in the case along the rotation direction of the charging roller. The surface airflow of the charging roller and the surface airflow of the photosensitive member collide near the inlet of the exhaust passage formed near the upstream side of the position where the charging roller and the photosensitive member face each other, the pressure increases, And exhausted from the exhaust passage. For this reason, the control gas containing discharge products etc. can be smoothly exhausted by passing through the discharge region.
[0051]
The case may be sized to cover the charging roller with a gap through which the surface airflow of the charging roller flows, and the case can be reduced in size.
[0052]
The invention according to claim 11 exposes the outer peripheral surface of the charged photosensitive member to form an electrostatic latent image, and supplies toner to the photosensitive member on which the electrostatic latent image is formed to form a toner image. An electrophotographic image forming apparatus for transferring the formed toner image to a recording medium; a contact charging roller disposed in contact with the outer peripheral surface of the photoconductor and rotating in a rotating direction with respect to the photoconductor; The outer peripheral surface of the contact charging roller is covered with a gap of a predetermined dimension along which the surface airflow flows along the outer peripheral surface of the photoconductor, and the rotation direction of the photoconductor is greater than the contact position between the photoconductor and the contact charging roller. A case in which an exhaust passage that is located in the vicinity of the upstream side and extends in a direction away from the photoconductor is formed, a control gas supply unit that supplies control gas, and a control gas supply unit that supplies the control gas Control gas to the outer periphery of the photoconductor A guide portion that guides the surface of the photoconductor and the contact charging roller as a surface airflow along the surface, and gas from the outside is closer to the photoconductor than the contact position of the photoconductor and the contact charging roller. And a second inflow port formed between the lower end side edge of the case and the outer peripheral surface of the photosensitive member with a gap allowing entry into the downstream side along the rotation direction.
[0053]
Therefore, the control gas supplied from the control gas supply unit is guided by the guide unit and flows as a surface layer airflow of the photoconductor, and is upstream from the contact position between the photoconductor and the contact charging roller in the rotation direction of the photoconductor. Is introduced into the discharge region on the side, and the generation of discharge products and the like in the discharge region on the upstream side thereof is suppressed, so that deterioration of the photoconductor is prevented and durability of the photoconductor is improved.
[0054]
Further, since the surface airflow of the photoconductor is generated in the same manner in the entire area in the longitudinal direction of the photoconductor, the generation of discharge products and the like is suppressed in the entire area in the longitudinal direction of the photoconductor.
[0055]
On the other hand, a gas from the outside flows into the discharge region downstream from the contact position between the photoconductor and the contact charging roller in the rotation direction of the photoconductor, and the gas flows from the second inlet to the downstream side. After flowing into the discharge region, it becomes the surface airflow of the contact charging roller and flows in the case along the rotation direction of the contact charging roller. The surface airflow of the contact charging roller and the surface airflow of the photoreceptor collide near the inlet of the exhaust passage formed near the upstream side of the contact position between the contact charging roller and the photoreceptor, and the pressure rises and blows out. It becomes an air current and is exhausted from the exhaust passage. For this reason, by passing through the discharge region, it is possible to smoothly exhaust the control gas containing discharge products and the like and the gas from the outside.
[0056]
Note that the control gas supplied from the control gas supply unit can be used as the gas from the outside flowing into the discharge region on the downstream side along the rotation direction of the photoconductor from the second inlet. In this case, a flow path that guides the control gas from the control gas supply unit to the second inflow port is formed. As a result, the generation of discharge products and the like can be suppressed in the downstream discharge area in the same manner as in the upstream discharge area, and further deterioration of the photoreceptor and durability can be improved.
[0057]
The case may be sized to cover the contact charging roller with a gap through which the surface airflow of the contact charging roller flows, and the case can be reduced in size.
[0058]
According to a twelfth aspect of the present invention, in the electrophotographic image forming apparatus according to the tenth or eleventh aspect of the present invention, the control gas supplied toward the outer peripheral surface of the photoconductor is spread over the entire area in the longitudinal direction of the photoconductor. A swirling flow generating means for generating a swirling flow is provided.
[0059]
Therefore, by causing the control gas to swirl and then supplying the control gas toward the surface of the photoconductor, the effect of replacing the surface airflow on the surface of the photoconductor with the control gas is enhanced.
[0060]
According to a thirteenth aspect of the present invention, in the electrophotographic image forming apparatus according to the twelfth aspect, the swirling flow generating means is disposed in a duct disposed in parallel with the longitudinal direction of the photosensitive member and in the duct. It is characterized by having an impeller made.
[0061]
Therefore, since the control gas flows through the inner space of the impeller along the longitudinal direction and the control gas is blown by the impeller, the control gas can be stably supplied to the entire region along the longitudinal direction of the photosensitive member.
[0062]
According to a fourteenth aspect of the present invention, in the electrophotographic image forming apparatus according to any one of the tenth to thirteenth aspects, a neutralizing unit is provided in the guide portion so as to face the outer peripheral surface of the photoconductor. It is characterized by.
[0063]
Therefore, it is possible to provide a static eliminating means without obstructing the surface airflow of the photoreceptor.
[0064]
According to a fifteenth aspect of the present invention, in the electrophotographic image forming apparatus according to the third or eleventh aspect of the present invention, a second counter roller is provided that is positioned at the second inflow port and rotates counter to the photoconductor. It is characterized by.
[0065]
Therefore, the introduction of gas from the outside through the second inlet is promoted by the rotation of the second counter roller. Further, the surface airflow of the photoconductor is peeled off by the rotation of the second counter roller, and discharge products remaining on the surface of the photoconductor are quickly removed.
[0066]
DETAILED DESCRIPTION OF THE INVENTION
A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a longitudinal sectional front view showing a schematic structure of an electrophotographic image forming apparatus, and FIG. 2 is a longitudinal sectional front view showing a part thereof enlarged.
[0067]
As shown in FIG. 1, the image forming apparatus according to the present embodiment is provided with a main body case 1, and in the main body case 1, a paper conveyance path 4 extending from the paper feed unit 2 to the paper discharge tray 3 is formed. A registration roller 5, a photoreceptor 6, a transfer belt 7, a fixing device 8, and the like are disposed on the paper conveyance path 4. Further, in the main body case 1, a control gas supply unit 9 that generates low-humidity air that is a control gas, a blower fan 9 a that blows low-humidity air generated by the control gas supply unit 9, and the outer peripheral surface of the photoreceptor 6 are exposed. Then, an optical writing means 10 for writing an electrostatic latent image is provided.
[0068]
The configuration of the control gas supply unit 9 that generates low-humidity air includes various configurations such as a dehumidifying configuration using a desiccant and a dehumidifying configuration by dissociating moisture into hydrogen ions and oxygen using a solid molecular electrolyte membrane. Configuration is acceptable.
[0069]
Toner is supplied to the surface of the photoreceptor 6 on which the electrostatic latent image is formed by exposure by the charging roller 11 and the optical writing means 10 that uniformly charge the surface of the photoreceptor 6 around the photoreceptor 6. A developing device 12 that visualizes the electrostatic latent image as a toner image, and a cleaning device 13 that removes the toner remaining on the surface of the photosensitive member 6 after the visualized toner image is transferred to a recording medium conveyed through the paper conveyance path 4. Etc. are arranged.
[0070]
The charging roller 11 is formed to have a length that is substantially the same as the length in the longitudinal direction of the photoconductor 6, and is arranged in parallel to the photoconductor 6. Further, the charging roller 11 is disposed in a non-contact manner on the outer peripheral surface of the photosensitive member 6, and its rotation direction is set to a direction that rotates with respect to the rotation direction of the photosensitive member 6, as indicated by an arrow (see FIG. 2). Has been. In the vicinity of the charging roller 11, a counter roller 14 that is an airflow blocking member and a case 15 are provided.
[0071]
The case 15 has a position facing the charging roller 11 on the outer peripheral surface of the photosensitive member 6, an upstream side in the rotation direction of the photosensitive member 6 with respect to a position facing the charging roller 11 on the outer peripheral surface of the photosensitive member 6, and The charging roller 11 is formed so as to surround a part of the outer peripheral surface and a part of the outer peripheral surface of the counter roller 14. Therefore, a part of the outer peripheral surface of the charging roller 11 and a part of the outer peripheral surface of the counter roller 14 are arranged so as to be exposed outside the case 15. An inlet 16 is formed in the upper part of the case 15, and the low-humidity air generated by the control gas supply unit 9 is blown through the supply pipe 9 b and flows into the case 15 from the inlet 16. The case 15 is formed with a width dimension that opposes the entire region in the longitudinal direction of the photosensitive member 6, and a plurality of inflow ports 16 are formed along the lateral width direction of the case 15, or slit-like along the lateral width direction. Is formed. Thereby, the low-humidity air supplied from the control gas supply unit 9 and flowing into the case 15 flows substantially evenly along the longitudinal direction of the photoreceptor 6.
[0072]
A scraper 17, which is a flexible contact member, is attached to an edge of the case 15 facing the upstream side along the rotation direction of the photoreceptor 6. The scraper 17 is formed of a flexible member having insulation properties such as polyurethane, rubber, resin, and the like, and is disposed so that the tip end thereof is in sliding contact with the outer peripheral surface of the photoreceptor 6. The scraper 17 slides the tip of the scraper 17 on the outer peripheral surface of the photoconductor 6, thereby peeling off the surface airflow of the photoconductor 6 from the surface portion of the photoconductor 6 and preventing the surface airflow from entering the case 15. . Thereby, the filling rate of the low-humidity air in case 15 can be raised.
[0073]
The counter roller 14 has substantially the same length as the charging roller 11 and is arranged in parallel to the charging roller 11. Further, the counter roller 14 is disposed close to the charging roller 11 in a non-contact manner with a slight gap, and is driven to rotate in the counter direction with respect to the charging roller 11 as indicated by an arrow (see FIG. 2). The diameter of the counter roller 14 is set smaller than the diameter of the charging roller 11.
[0074]
A seal 18 for preventing leakage of low-humidity air flowing into the case 15 is attached to an edge portion of the case 15 that faces the counter roller 14, and the free end side of the seal 18 is an outer peripheral surface of the counter roller 14. Is in sliding contact.
[0075]
In such a configuration, at the time of image formation, the photosensitive member 6 and the charging roller 11 are rotationally driven in the direction of the arrow, and discharge is performed between the charging roller 11 and the photosensitive member 6, and discharge of ozone, NOx, or the like is caused by this discharge. Product is generated. If no measures are taken when NOx occurs, the NOx chemically changes to ammonium nitrate due to the influence of moisture, and the ammonium nitrate adheres to the surface of the photoreceptor 6 to cause image flow and the like. The photoreceptor 6 is deteriorated.
[0076]
Therefore, in the present embodiment, the low-humidity air generated by the control gas supply unit 9 is supplied into the case 15 at the time of image formation. When the low-humidity air flows into the case 15 from the inflow port 16, the low-humidity air flows as shown by a two-dot chain line. The inflow of low-humidity air into the case 15 is performed substantially evenly along the longitudinal direction of the photoconductor 6.
[0077]
First, a part of the low-humidity air that has flowed into the case 15 becomes a surface airflow of the charging roller 11 and flows along the rotation direction of the charging roller 11, and the discharge is a region where the charging roller 11 and the photoreceptor 6 are close to each other. Introduced into the area. Thereby, the chemical change from NOx, which is a discharge product in the discharge region in the case 15, to ammonium nitrate can be suppressed, deterioration of the photoconductor 6 caused by ammonium nitrate is prevented, and durability of the photoconductor 6 is improved. .
[0078]
Note that the surface layer airflow of the charging roller 11 due to the low-humidity air flowing into the case 15 is generated in the same manner in the entire longitudinal direction of the charging roller 11, so that the chemical from NOx to ammonium nitrate in the entire longitudinal direction of the photoreceptor 6. Change can be suppressed.
[0079]
Part of the low-humidity air introduced to the discharge region in the case 15 passes through the gap between the photoconductor 6 and the charging roller 11, and the charging roller 11 and the photoconductor 6 face each other on the outer peripheral surface of the photoconductor 6. It is introduced into the discharge region on the downstream side along the rotation direction of the photosensitive member 6 from the position, that is, the discharge region located outside the case 15. Thereby, the chemical change from NOx to ammonium nitrate is suppressed even in the discharge region outside the case 15, and further deterioration prevention and durability improvement of the photoreceptor 6 can be achieved.
[0080]
Part of the low-humidity air that has passed through the gap between the photoconductor 6 and the charging roller 11 flows along the rotation direction of the charging roller 11 as a surface airflow of the charging roller 11, and the other part of the photoconductor. 6 flows along the rotational direction of the photoreceptor 6. The low-humidity air flowing as a surface airflow of the charging roller 11 flows to a position facing the counter roller 14, then collides with the surface airflow of the counter roller 14, is pushed back, and is prevented from entering the case 15 again. . At the time of this collision, since the diameter of the counter roller 14 is smaller than the diameter of the charging roller 11, the surface airflow of the counter roller 14 collides acutely with the surface airflow of the charging roller 11, and the surface airflow of the counter roller 14 is The surface airflow of the charging roller 11 is in a state of biting, and the surface airflow of the charging roller 11 is more effectively prevented from entering the space in the case 15. For this reason, the discharge product contained in the low-humidity air that flows out of the case 15 as the surface airflow of the charging roller 11 after passing through the discharge region is prevented from entering the case 15.
[0081]
Part of the low-humidity air that has been introduced to the discharge region and did not enter the gap between the photosensitive member 6 and the charging roller 11 returns from the discharge region and swirls within the case 15. Thereafter, the low-humidity air that is part of the low-humidity air that has flowed into the case 15 and has not been introduced into the discharge region in the case 15 joins, and is exhausted outside the case 15 as a surface airflow of the counter roller 14.
[0082]
For this reason, all of the low-humidity air that has flowed into the case 15 is exhausted to the outside of the case 15 in sequence, so that no discharge product, ammonium nitrate, or the like remains in the case 15.
[0083]
In the present embodiment, the low-humidity air has been described as an example of the control gas. However, the control gas is controlled so as to suppress the generation of discharge products such as NOx and ozone that cause the photoreceptor 6 to deteriorate. Various gases such as inert gas can be used as the control gas.
[0084]
Further, in the present embodiment, the case where the low-humidity air is supplied into the case 15 using the blower fan 9a has been described as an example. However, the surface airflow of the charging roller 11 is exhausted to the outside of the case 15 and the case 15 is supplied. The low-humidity air may be supplied by utilizing the negative pressure in the inside 15, and in that case, the blower fan 9 a becomes unnecessary.
[0085]
Further, in the present embodiment, the counter roller 14 having a smooth surface has been described as an example. However, instead of the counter roller 14, a counter roller 14a having an outer peripheral surface processed as shown in FIG. Alternatively, as shown in FIG. 4, a counter roller 14b in which a brush 19 is implanted on the outer peripheral surface may be used. Examples of the surface finishing method include cutting, rolling, sand blasting, and etching.
[0086]
In the counter roller 14a whose outer peripheral surface is processed and the counter roller 14b in which the brush 19 is planted on the outer peripheral surface, the amount of surface airflow can be increased compared to the counter roller 14, and the surface airflow of the charging roller 11 is increased in the case 15. Can be prevented more effectively.
[0087]
Next, a second embodiment of the present invention will be described with reference to FIGS. In addition, the same part as other embodiment demonstrated previously is shown with the same code | symbol, and description is also abbreviate | omitted (it is the same also in each following embodiment).
[0088]
The present embodiment has a non-contact type charging roller 11 with respect to the photoreceptor 6, a counter roller 14 disposed close to the charging roller 11, and a control gas supply unit 9 that supplies low-humidity air. Is the same as in the first embodiment.
[0089]
This embodiment is different from the first embodiment in the shape of the case 20 to which low-humidity air is supplied.
[0090]
The case 20 has a position facing the charging roller 11 on the outer peripheral surface of the photoconductor 6 and an upstream side in the rotation direction of the photoconductor 6 with respect to a position facing the charging roller 11 on the outer peripheral surface of the photoconductor 6. It is formed so as to surround the downstream side and the entire charging roller 11 and counter roller 14. The space in the case 20 is partitioned into an upstream space 22 and a downstream space 23 by a charging roller 11, a counter roller 14, a seal 18, and a seal attachment plate 21 to which the seal 18 is attached. The upstream space 22 is a space upstream from the position facing the charging roller 11 along the rotation direction of the photoconductor 6, and the downstream space 23 is between the charging roller 11 along the rotation direction of the photoconductor 6. It is a space downstream from the facing position.
[0091]
An inlet 16 and an exhaust port 24 are formed in the upper part of the case 20. The inflow port 16 is formed in communication with the upstream space 22, and the exhaust port 24 is formed in communication with the downstream space 23. The exhaust port 24 is always in a negative pressure state during image formation due to the action of a suction force by driving a suction pump described later.
[0092]
FIG. 6 shows the arrangement state of the inlet 16 and the outlet 24 formed in the case 20 and the low-humidity air supplied from the control gas supply unit 9 flows substantially evenly along the longitudinal direction of the photoreceptor 6. It is a perspective view explaining a structure. A plurality of inflow ports 16 and a plurality of exhaust ports 24 are formed in the case 20 along the longitudinal direction of the photoreceptor 6.
[0093]
A duct case 27 in which a supply side duct 25 and an exhaust side duct 26 are formed is fixed to the upper part of the case 20. The supply side duct 25 and the exhaust side duct 26 are formed in parallel to the photoreceptor 6, the supply side duct 25 communicates with each inflow port 16, and the exhaust side duct 26 communicates with each exhaust port 24. .
[0094]
On one end side of the duct case 27, a supply side joint 28 that communicates with the supply side duct 25 and an exhaust side joint 29 that communicates with the exhaust side duct 26 are provided. The joints 28 and 29 are the supply-side body joint 30a and the exhaust-side body joint provided in the body case 1 when the case 20 with the duct case 27 fixed is set in the body case 1 of the image forming apparatus. 30b.
[0095]
The present embodiment has a structure in which the blower fan 9a described in FIG. 1 is not used and a suction pump (not shown) is provided on the exhaust side, and the inflow ports 16 are all formed in the same opening size. The opening 24 is formed so that the opening size is gradually reduced toward the exhaust side joint 29 where the suction force of the suction pump acts more. Thereby, the amount of low-humidity air sucked from each exhaust port 24 becomes substantially equal. Since the supply of the low-humidity air from the inlet 16 is performed by the negative pressure in the case 20, even if the opening size of each inlet 16 is the same, the inflow of the low-humidity air from each inlet 16 is performed substantially evenly. .
[0096]
In such a configuration, the low-humidity air generated in the control gas supply unit 9 flows into the upstream space 22 from the inlet 16 through the supply-side duct 25, and the low-humidity air is indicated by a two-dot chain line. Flowing.
[0097]
First, a part of the low-humidity air that has flowed into the upstream space 22 flows along the rotation direction of the charging roller 11 as a surface airflow of the charging roller 11, and in a region where the charging roller 11 and the photoreceptor 6 are close to each other. It is introduced into a certain discharge area. Thereby, the chemical change from NOx, which is a discharge product in the discharge region in the upstream space 22, to ammonium nitrate can be suppressed, deterioration of the photoconductor 6 caused by ammonium nitrate is prevented, and the durability of the photoconductor 6 is improved. Up.
[0098]
Note that the surface layer airflow of the charging roller 11 when low-humidity air flows into the upstream space 22 is generated in the same manner in the entire area in the longitudinal direction of the charging roller 11. The chemical change from ammonium nitrate to ammonium nitrate can be suppressed.
[0099]
Part of the low-humidity air introduced up to the discharge area in the upstream space 22 passes through the gap between the photoconductor 6 and the charging roller 11 and is introduced into the discharge area in the downstream space 23 in the case 20. The Thereby, even in the discharge region in the downstream space 23, the chemical change from NOx to ammonium nitrate is suppressed, so that further deterioration prevention and durability improvement of the photoreceptor 6 can be achieved.
[0100]
Part of the low-humidity air that has passed through the gap between the photoconductor 6 and the charging roller 11 and introduced into the discharge area in the downstream space 23 becomes the surface airflow of the charging roller 11 and rotates the charging roller 11. The other part flows as a surface layer airflow of the photoconductor 6 and flows along the rotation direction of the photoconductor 6, and a gap between the lower end side edge of the case 20 and the outer peripheral surface of the photoconductor 6. The portion 31 flows out of the downstream space 23. From this gap portion 31, ambient air flows into the downstream space 23 so as to rub against the surface airflow of the photoreceptor 6.
[0101]
The low-humidity air that flows as a surface airflow of the charging roller 11 in the downstream space 23 flows to a position facing the counter roller 14, collides with the surface airflow of the counter roller 14, is pushed back, and again the upstream space 22. It is blocked from entering. For this reason, discharge products and the like contained in the low-humidity air flowing in the downstream space 23 as a surface airflow of the charging roller 11 after passing through the discharge region are prevented from entering the upstream space 22.
[0102]
Part of the low-humidity air introduced up to the discharge region in the upstream space 22 and not entering the gap between the photosensitive member 6 and the charging roller 11 returns from the discharge region and in the upstream space 22. After swirling, it joins with the low-humidity air that is part of the low-humidity air that has flowed into the upstream space 22 and has not been introduced into the discharge region in the upstream space 22, and becomes the surface airflow of the counter roller 14. It flows out into the space 23.
[0103]
Then, the three systems of gas flowing into the downstream space 23, that is, the low-humidity air that has flown as the surface airflow of the charging roller 11 after passing through the gap portion between the charging roller 11 and the photoreceptor 6 (the first system) Gas), low-humidity air (second system gas) flowing from the upstream space 22 as a surface airflow of the counter roller 14, and air entering from the outside of the case 20 through the gap 31 (third system gas) Is exhausted from the exhaust port 24 by driving the suction pump.
[0104]
In this way, all of the low-humidity air that has flowed into the upstream space 22 sequentially flows into the downstream space 23 and is further exhausted from the exhaust port 24 to the outside of the downstream space 23. In addition, the discharge product, ammonium nitrate, or the like does not remain in the downstream space 23.
[0105]
Next, a third embodiment of the present invention will be described with reference to FIG. The basic structure of this embodiment is the same as that of the second embodiment (see FIG. 5). The difference of this embodiment from the second embodiment is that instead of the counter roller 14 as an airflow blocking member. The plurality of plate-like barriers 32 is provided.
[0106]
The plate-like barrier 32 is arranged with one end facing the outer peripheral surface of the charging roller 11 close to the other and the other end facing the exhaust port 24. A channel 33 is formed between adjacent plate-like barriers 32.
[0107]
In such a configuration, the present embodiment has the same effect as the second embodiment, and the chemical change from NOx to ammonium nitrate can be suppressed by efficiently introducing low-humidity air into the discharge region. The deterioration of the photosensitive member 6 can be prevented, and the durability of the photosensitive member 6 can be improved.
[0108]
Further, by providing the plate-like barrier 32, the surface layer airflow of the charging roller 11 is separated from the charging roller 11 by the vortex generation accompanying the pressure fluctuation before and after the plate-like barrier 32, and becomes a negative pressure state by driving the suction pump. The air is sucked along the plate-like barrier 32 toward the exhaust port 24. As a result, the surface airflow of the charging roller 11 is prevented from entering the upstream space 22.
[0109]
Next, a fourth embodiment of the present invention will be described with reference to FIG. The basic structure of the present embodiment is the same as that of the second embodiment (see FIG. 5). This embodiment is different from the second embodiment in that the cleaning is located in the upstream space 22. A second counter roller 35 and a seal 36 that are positioned facing the roller 34 and the gap 31 are added.
[0110]
The cleaning roller 34 has a brush that contacts the outer peripheral surface of the charging roller 11, and cleans the charging roller 11.
[0111]
The second counter roller 35 is disposed close to the outer peripheral surface of the photoconductor 6 and is driven to rotate in the counter direction with respect to the photoconductor 6.
[0112]
One end of the seal 36 is fixed to the case 20, and the free end is in sliding contact with the outer peripheral surface of the second counter roller 35, and the surface airflow of the second counter roller 35 follows the rotation direction of the second counter roller 35. Thus, it is prevented from being exhausted out of the downstream space 23 as it is.
[0113]
In such a configuration, as described in the second embodiment, all of the low-humidity air that has flowed into the upstream space 22 sequentially flows into the downstream space 23, and further from the exhaust port 24. Since the exhaust gas is exhausted to the outside of the downstream space 23, there remains no discharge product or the like in the upstream space 22 and the downstream space 23. For this reason, even when the cleaning roller 34 is installed in the upstream space 22 and the charging roller 11 is cleaned, the discharge products remaining in the upstream space 22 at the time of cleaning are left on the outer peripheral surface of the charging roller 11. There is no occurrence of pressing and fixing, and the charging performance of the charging roller 11 can be maintained well over a long period of time.
[0114]
Further, the rotation of the second counter roller 35 peels off the surface airflow of the photoconductor 6, so that the discharge products remaining on the surface of the photoconductor 6 can be quickly removed.
[0115]
Next, a fifth embodiment of the present invention will be described with reference to FIG. The basic structure of the present embodiment is the same as that of the second embodiment (see FIG. 5). The difference of the present embodiment from the second embodiment is that the photoconductor in the second embodiment. In contrast to the charging roller 11 that is not in contact with the charging roller 11 in this embodiment, a contact charging roller 37 is used in the present embodiment. Further, the gap 31 described in the second embodiment functions as the second inlet 38 in the present embodiment.
[0116]
The contact charging roller 37 is formed to have a length that is substantially the same as the length of the photosensitive member 6 in the longitudinal direction, and is arranged in parallel with the photosensitive member 6 and in contact with the outer peripheral surface of the photosensitive member 6. . The rotation direction of the contact charging roller 37 is a direction along with the rotation direction of the photosensitive member 6 as indicated by an arrow.
[0117]
In such a configuration, the low-humidity air generated by the control gas supply unit 9 flows into the upstream space 22 from the inflow port 16, and the low-humidity air flows as indicated by a two-dot chain line.
[0118]
First, a part of the low-humidity air flowing into the upstream space 22 becomes a surface layer airflow of the contact charging roller 37 and flows along the rotation direction of the contact charging roller 37, and the contact charging roller 37 and the photoconductor 6 approach each other. It is introduced into the discharge area, which is the area to be discharged. Thereby, the chemical change from NOx, which is a discharge product in the discharge region in the upstream space 22, to ammonium nitrate can be suppressed, deterioration of the photoconductor 6 caused by ammonium nitrate is prevented, and the durability of the photoconductor 6 is improved. Up.
[0119]
Note that the surface airflow of the contact charging roller 37 when low-humidity air flows into the upstream space 22 is generated in the same manner in the entire area of the contact charging roller 37 in the longitudinal direction. The chemical change from NOx to ammonium nitrate can be suppressed.
[0120]
The low-humidity air introduced up to the discharge region in the upstream space 22 is a part of the low-humidity air that has flowed into the upstream space 22 after returning from the discharge region and turning in the upstream space 22 The low-humidity air that has not been introduced into the discharge region in the space 22 joins and becomes a surface airflow of the counter roller 14 and flows out into the downstream space 23.
[0121]
On the other hand, when the exhaust gas from the exhaust port 24 causes the downstream space 23 to have a negative pressure, ambient air flows into the downstream space 23 from the second inlet 38, and this air flows into the downstream space 23. Then, a part of the air flows into the surface space of the charging roller 11 and flows along the rotation direction of the charging roller 11 in the downstream space 23. However, the surface airflow flows to a position facing the counter roller 14, then collides with the surface airflow of the counter roller 14, is pushed back, and is prevented from entering the upstream space 22. Therefore, it is possible to remove discharge products and the like from the discharge region in the downstream space 23 and prevent the discharge products and the like from entering the upstream space 22.
[0122]
Then, two systems of gas flowing into the downstream space 23, that is, low-humidity air (first system gas) flowing from the upstream space 22 as a surface airflow of the counter roller 14, and flowing in from the second inlet 38. The surrounding air (second system gas) is exhausted from the exhaust port 24 by driving the suction pump.
[0123]
In this way, all of the low-humidity air that has flowed into the upstream space 22 sequentially flows into the downstream space 23, and is further exhausted from the exhaust port 24 to the outside of the downstream space 23. In addition, air that has flowed in from the second inlet 38 and has removed discharge products and the like from the discharge region in the downstream space 23 is also exhausted from the exhaust port 24 to the outside of the downstream space 23. For this reason, no discharge product or the like remains in the upstream space 22 and the downstream space 23.
[0124]
In the present embodiment, the case where ambient air is used as an external gas to be introduced from the second inflow port 38 has been described as an example, but the low-humidity air generated by the control gas supply unit 9 is used as an example. You may make it flow in from this 2nd inflow port 38. FIG. In this case, a flow path that guides the low-humidity air from the control gas supply unit 9 to the second inflow port 38 is formed. By using low-humidity air as an external gas flowing in from the second inlet 38, the price change from NOx to ammonium nitrate in the discharge region in the downstream space 23 is the same as in the discharge region in the upstream space 22. Can be suppressed.
[0125]
Next, a sixth embodiment of the present invention will be described with reference to FIG. The basic structure of this embodiment is the same as that of the fifth embodiment (see FIG. 9), and a contact charging roller 37 is used. The present embodiment differs from the fifth embodiment in that the cleaning roller 34 located in the upstream space 22 and the second counter roller located in the second inlet 38 are different from the fifth embodiment. 35 and a seal 36 are added.
[0126]
The cleaning roller 34 has a brush that contacts the outer peripheral surface of the contact charging roller 37, and cleans the contact charging roller 37.
[0127]
The second counter roller 35 is disposed close to the outer peripheral surface of the photoconductor 6 and is driven to rotate in the counter direction with respect to the photoconductor 6.
[0128]
One end of the seal 36 is fixed to the case 20, and the free end is in sliding contact with the outer peripheral surface of the second counter roller 35, and the surface airflow of the second counter roller 35 follows the rotation direction of the second counter roller 35. Thus, it is prevented from being exhausted out of the downstream space 23 as it is.
[0129]
In such a configuration, as described in the fifth embodiment, all of the low-humidity air that has flowed into the upstream space 22 sequentially flows into the downstream space 23, and further from the exhaust port 24. The gas is exhausted out of the downstream space 23. In addition, air that has flowed in from the second inlet 38 and has removed discharge products and the like from the discharge region in the downstream space 23 is also exhausted from the exhaust port 24 to the outside of the downstream space 23. For this reason, no discharge product or the like remains in the upstream space 22 and the downstream space 23.
[0130]
For this reason, even if the cleaning roller 34 is installed in the upstream space 22 and the contact charging roller 37 is cleaned, the discharge products remaining in the upstream space 22 at the time of cleaning are removed from the outer periphery of the contact charging roller 37. The charging performance of the contact charging roller 37 can be satisfactorily maintained for a long time without being pressed against the surface to be fixed.
[0131]
Further, the rotation of the second counter roller 35 peels off the surface airflow of the photoconductor 6, so that the discharge products remaining on the surface of the photoconductor 6 can be quickly removed.
[0132]
Next, a seventh embodiment of the present invention will be described with reference to FIG. The image forming apparatus according to the present embodiment includes a photoconductor 6, a charging roller 11, a control gas supply unit 9 that generates low-humidity air that is a control gas, an optical writing unit 10, and the like in the main body case 1. This is common to the first to fourth embodiments described above.
[0133]
The charging roller 11 is disposed in close contact with the outer peripheral surface of the photosensitive member 6 in a non-contact manner, and the charging roller 11 is rotationally driven in a direction to rotate with respect to the photosensitive member 6 as indicated by an arrow.
[0134]
A case 39 for storing the charging roller 11 is provided in the vicinity of the charging roller 11, and a gap of a predetermined dimension through which a surface airflow flows between the inner peripheral surface of the case 39 and the outer peripheral surface of the charging roller 11. 40 is formed. Further, the case 39 is formed with an exhaust passage 41, a duct 42, a guide portion 43, and a second inflow port 44.
[0135]
The exhaust passage 41 is located near the upstream side in the rotation direction of the photoconductor 6 relative to the position where the photoconductor 6 and the charging roller 11 face each other, and is formed to extend away from the photoconductor 6. .
[0136]
The duct 42 is a portion to which the low-humidity air generated by the control gas supply unit 9 is supplied, and this duct 42 is the same as the supply-side duct 25 described in the second embodiment (see FIG. 6). The length of the photosensitive member 6 is substantially the same as the length in the longitudinal direction, and the photosensitive member 6 is disposed in parallel. An impeller 45 that rotates when low-humidity air flows through the duct 42 is provided in the duct 42. The duct 42 and the impeller 45 form a swirl flow generating means 46 that generates a swirl flow in the low-humidity air supplied toward the outer peripheral surface of the photosensitive member 6 after passing through the duct 42. Yes. The low-humidity air turned into a swirl flow by the swirl flow generating means 46 is blown toward the outer peripheral surface of the photoreceptor 6 through a passage 49 formed between the side surface of the case 39 and the cleaning blade 47 and the blade holding member 48. Is done.
[0137]
The guide unit 43 directs the low-humidity air supplied toward the outer peripheral surface of the photoconductor 6 through the duct 42 as a surface airflow along the outer peripheral surface of the photoconductor 6 toward the position where the photoconductor 6 and the charging roller 11 face each other. It is a guiding member, and is formed in a circular arc shape facing the outer peripheral surface of the photoreceptor 6 at equal intervals.
[0138]
A neutralizing lamp 50 as a neutralizing means is attached in the guide portion 43 so as to face the outer peripheral surface of the photoreceptor 6. The static elimination lamp 50 is positioned so as not to protrude from the surface of the guide portion 43.
[0139]
The second inflow port 44 is formed on the downstream side in the rotation direction of the photoconductor 6 with respect to the position where the photoconductor 6 and the charging roller 11 are opposed to each other. It is formed as a gap between the outer peripheral surface. A counter roller 51 and a seal 52 are attached to the case 39 at a position facing the second inlet 44.
[0140]
The counter roller 51 is disposed close to the outer peripheral surface of the photoconductor 6 and is driven to rotate in the counter direction with respect to the photoconductor 6.
[0141]
The seal 52 has one end fixed to the case 39 and the free end slidably contacted with the outer peripheral surface of the counter roller 51, and the surface airflow of the counter roller 51 remains as it is along the rotation direction of the counter roller 51. 44 is prevented from being exhausted.
[0142]
In such a configuration, the low-humidity air supplied from the control gas supply unit 9 becomes a surface airflow of the photoconductor 6 and is guided by the guide unit 43 and flows toward the position where the photoconductor 6 and the charging roller 11 face each other. Further, a part of the surface airflow flows through a gap portion between the photoconductor 6 and the charging roller 11. Thus, the low humidity air can be satisfactorily introduced into the discharge areas on the upstream side and the downstream side along the rotation direction of the photoconductor 6 with respect to the position where the charging roller 11 and the photoconductor 6 face each other. Thus, the chemical change from NOx to ammonium nitrate can be suppressed, the deterioration of the photoreceptor 6 caused by ammonium nitrate is prevented, and the durability of the photoreceptor 6 is improved.
[0143]
In addition, since the surface airflow of the photoconductor 6 is generated in the same manner in the entire area in the longitudinal direction of the photoconductor 6, the chemical change from NOx to ammonium nitrate can be suppressed in the entire area in the longitudinal direction of the photoconductor 6.
[0144]
Further, since the low-humidity air that becomes the surface airflow of the photosensitive member 6 is swirled by the swirling flow generating means 46 and then supplied toward the surface of the photosensitive member 6, the low-humidity air is directed toward the surface of the photosensitive member 6. Therefore, the effect of substituting the surface airflow of the photoreceptor 6 with low-humidity air is enhanced. Furthermore, since the position where the low-humidity air is supplied to the outer peripheral surface of the photoconductor 6 is the position immediately after the surface airflow of the photoconductor 6 is peeled off by the cleaning blade 47, the surface airflow of the photoconductor 6 is replaced with low-humidity air. The effect to do becomes higher.
[0145]
The low-humidity gas that has passed through the gap between the photoconductor 6 and the charging roller 11 then becomes the surface airflow of the charging roller 11 and flows through the gap 40 in the case 39 along the rotation direction of the charging roller 11.
[0146]
The surface airflow of the charging roller 11 and the surface airflow of the photosensitive member 6 collide near the inlet of the exhaust passage 41 to increase the pressure, and are discharged from the exhaust passage 41 as a blown airflow. For this reason, the low-humidity gas containing discharge products etc. can be smoothly exhausted out of the case 39 by passing through the discharge region.
[0147]
Further, the rotation of the counter roller 51 peels off the surface airflow of the photoconductor 6, so that the discharge products remaining on the surface of the photoconductor 6 can be quickly removed.
[0148]
Next, an eighth embodiment of the present invention will be described with reference to FIG. The basic structure of this embodiment is the same as that of the seventh embodiment (see FIG. 11), and this embodiment is different from the seventh embodiment in that the photoconductor in the seventh embodiment. In contrast to the charging roller 11 that is not in contact with the charging roller 11 in this embodiment, a contact charging roller 37 is used in the present embodiment.
[0149]
The contact charging roller 37 is formed to have a length that is substantially the same as the length of the photosensitive member 6 in the longitudinal direction, and is arranged in parallel with the photosensitive member 6 and in contact with the outer peripheral surface of the photosensitive member 6. . The rotation direction of the contact charging roller 37 is a direction along with the rotation direction of the photosensitive member 6 as indicated by an arrow.
[0150]
The exhaust passage 41 is located near the upstream side in the rotation direction of the photosensitive member 6 with respect to the contact position between the photosensitive member 6 and the contact charging roller 37 and extends in a direction away from the photosensitive member 6. Yes.
[0151]
In such a configuration, the low-humidity air supplied from the control gas supply unit 9 becomes the surface layer airflow of the photoconductor 6, is guided by the guide unit 43, and flows toward the position where the photoconductor 6 and the contact charging roller 37 face each other. Then, it is introduced into the discharge region upstream of the contact position between the photoconductor 6 and the contact charging roller 37 along the rotation direction of the photoconductor 6, and NOx, which is a discharge product in the discharge region on the upstream side, is converted into ammonium nitrate. The chemical change can be suppressed, the deterioration of the photoreceptor 6 caused by ammonium nitrate is prevented, and the durability of the photoreceptor 6 is improved.
[0152]
Since the surface airflow of the photoconductor 6 is generated in the same manner in the entire area in the longitudinal direction of the photoconductor 6, a chemical change from NOx to ammonium nitrate can be suppressed in the entire area in the longitudinal direction of the photoconductor 6.
[0153]
On the other hand, ambient air flows from the second inflow port 44 into the discharge area downstream of the contact position between the photoreceptor 6 and the contact charging roller 37 along the rotation direction of the photoreceptor 6. After flowing into the discharge region on the downstream side, it becomes the surface layer air current of the contact charging roller 37 and flows through the gap 40 in the case 39 along the rotation direction of the contact charging roller 37.
[0154]
The surface airflow of the contact charging roller 37 and the surface airflow of the photosensitive member 6 collide near the inlet of the exhaust passage 41 and the pressure rises to become a blown airflow and is exhausted from the exhaust passage 41. For this reason, by passing through the discharge region, the low-humidity air containing discharge products and the surrounding air can be smoothly exhausted.
[0155]
Note that low-humidity air supplied from the control gas supply unit 9 can also be used as an external gas that flows from the second inlet 44 into the discharge region on the downstream side along the rotation direction of the photosensitive member 6. In this case, a flow path that guides the low-humidity air from the control gas supply unit 9 to the second inlet 44 is formed in the case 39. As a result, the generation of discharge products and the like can be suppressed in the downstream discharge area in the same manner as in the upstream discharge area, and further deterioration of the photoreceptor and durability can be improved.
[0156]
In the present embodiment, by installing the counter roller 51 at the second inlet 44, the surface layer air current of the photoconductor 6 is peeled off by the rotation of the counter roller 51, and the discharge products and the like remaining on the surface of the photoconductor 6. The removal can be performed quickly, and the introduction of ambient air to the downstream discharge region is promoted.
[0157]
If ring-shaped grooves are formed on both ends of the contact charging roller 37 in the longitudinal direction, the low-humidity air supplied from the control gas supply unit 9 passes through the grooves and the contact charging roller 37 on the outer peripheral surface of the photoreceptor 6. It is possible to allow the photosensitive member 6 to flow downstream from the contact portion. This eliminates the need to form the second inlet 44 shown in the figure or a flow path that guides the low-humidity air from the control gas supply unit 9 to the second inlet 44.
[0158]
【The invention's effect】
According to the electrophotographic image forming apparatus of the first aspect of the present invention, the discharge product in the discharge region of the charging roller that is partly surrounded by the case and is opposed to the photosensitive member in a non-contact manner. And the like, and it is possible to prevent discharge products and the like from remaining in the case, thereby preventing deterioration of the photoreceptor and improving durability.
[0159]
According to the electrophotographic image forming apparatus of the second aspect of the present invention, the generation of discharge products or the like in the discharge region of the charging roller which is entirely surrounded by the case and is disposed so as to face the photosensitive member in a non-contact manner. Further, it is possible to suppress the discharge product and the like from remaining in the case, and it is possible to prevent deterioration of the photoreceptor and improve durability.
[0160]
According to the electrophotographic image forming apparatus of the third aspect of the present invention, the generation of discharge products and the like in the discharge region of the contact charging roller which is surrounded by the case and is in contact with the photosensitive member. Further, it is possible to suppress the discharge product and the like from remaining in the case, and it is possible to prevent deterioration of the photoreceptor and improve durability.
[0161]
According to a fourth aspect of the present invention, in the electrophotographic image forming apparatus according to any one of the first to third aspects, the edge portion of the case facing the upstream side along the rotation direction of the photoconductor. Since the flexible contact member that is in sliding contact with the outer peripheral surface of the photoconductor is provided, the surface airflow of the photoconductor can be peeled off from the outer peripheral surface of the photoconductor by the flexible contact member. Intrusion into the case can be prevented, the filling of the control gas into the case can be enhanced, and the performance of suppressing the generation of discharge products and the like in the discharge region can be enhanced.
[0162]
According to a fifth aspect of the present invention, in the electrophotographic image forming apparatus according to any one of the first to fourth aspects, the airflow blocking member is disposed in the vicinity of the charging roller and is opposed to the charging roller. Since the counter roller that rotates the counter is provided, the surface airflow of the counter roller collides with the surface airflow of the charging roller, and this collision causes the surface airflow of the charging roller to enter the space in the case or the upstream space. This can prevent the deterioration of the photoconductor and increase the durability of the photoconductor.
[0163]
  Claim5According to the described invention, the claimsAny one of 1 to 4In the electrophotographic image forming apparatus described above, since the outer peripheral surface of the counter roller is roughened, the amount of surface airflow of the counter roller is increased by the roughening, and the surface airflow of the charging roller is increased in the space in the case. Or it can prevent more effectively entering upstream space.
[0164]
  Claim6According to the described invention, the claimsAny one of 1 to 5In the electrophotographic image forming apparatus described above, since the diameter of the counter roller is smaller than the diameter of the charging roller, the surface airflow of the counter roller collides acutely with the surface airflow of the charging roller, and the counter roller Thus, the surface airflow of the charging roller bites into the surface airflow of the charging roller, and the surface airflow of the charging roller can be more effectively prevented from entering the space in the case or the upstream space.
[0165]
  Claim7According to the described invention, the claimsAny one of 1 to 4In the electrophotographic image forming apparatus described above, since the brush is implanted on the outer peripheral surface of the counter roller, the amount of the surface airflow of the counter roller is increased by the brush implantation, and the surface airflow of the charging roller is Or it can prevent more effectively entering upstream space.
[0166]
  Claim8 andAccording to the invention described in claim 9, the claim2 or 3ListedIn addition to the effects of the invention ofAs the airflow prevention member, one end is close to the outer peripheral surface of the charging roller and the other end is opposed to the exhaust port.pluralPlateTo form a channel between adjacent plate membersThe surface airflow of the charging roller is plate-likeElementPlate-like toward the exhaust port, which is peeled off from the charging roller by the vortex generated by pressure fluctuation before and afterElementThe surface airflow of the charging roller can be prevented from entering the upstream space.
[0167]
According to the electrophotographic image forming apparatus of the tenth aspect of the present invention, the generation of discharge products or the like is generated in the discharge region of the charging roller which is entirely surrounded by the case and is disposed so as to face the photoreceptor in a non-contact manner. It is possible to suppress the deterioration of the photosensitive member and improve the durability.
[0168]
According to the electrophotographic image forming apparatus of the eleventh aspect of the present invention, the generation of discharge products and the like in the discharge region of the contact charging roller which is surrounded by the case and is in contact with the photosensitive member. It is possible to suppress the deterioration of the photosensitive member and improve the durability.
[0169]
According to a twelfth aspect of the present invention, in the electrophotographic image forming apparatus according to the tenth or eleventh aspect, the control gas supplied toward the outer peripheral surface of the photoconductor is spread over the entire area in the longitudinal direction of the photoconductor. Since there is a swirling flow generating means for generating a swirling flow across the surface, the effect of substituting the surface airflow on the surface of the photoreceptor with the control gas is enhanced, and the generation of discharge products and the like in the discharge region of the contact charging roller is suppressed. The effect can be enhanced.
[0170]
According to a thirteenth aspect of the present invention, in the electrophotographic image forming apparatus according to the twelfth aspect, the swirling flow generating means includes a duct disposed in parallel with the longitudinal direction of the photosensitive member, and the duct. Therefore, the control gas can be stably supplied to the entire region along the longitudinal direction of the photosensitive member.
[0171]
According to a fourteenth aspect of the present invention, in the electrophotographic image forming apparatus according to any one of the tenth to thirteenth aspects, a neutralizing unit is provided in the guide portion so as to face the outer peripheral surface of the photoconductor. Therefore, the charge eliminating means can be provided without obstructing the surface airflow of the photoreceptor.
[0172]
According to a fifteenth aspect of the present invention, in the electrophotographic image forming apparatus according to the third or eleventh aspect, the second counter roller positioned at the second inlet and counter-rotating with respect to the photoconductor is provided. Since it is provided, introduction of gas from the outside from the second inlet can be promoted, and the discharge air current remaining on the surface of the photoreceptor can be quickly removed by peeling off the surface airflow of the photoreceptor.
[Brief description of the drawings]
FIG. 1 is a longitudinal front view showing a schematic structure of an image forming apparatus according to a first embodiment of the present invention.
FIG. 2 is a longitudinal front view showing a part thereof in an enlarged manner.
FIG. 3 is a front view showing a modification of the counter roller.
FIG. 4 is a front view showing another modified example of the counter roller.
FIG. 5 is a longitudinal front view showing a part of an image forming apparatus according to a second embodiment of the present invention.
FIG. 6 is an exploded perspective view showing a low-humidity air supply and exhaust structure.
FIG. 7 is a longitudinal front view showing a part of an image forming apparatus according to a third embodiment of the present invention.
FIG. 8 is a longitudinal front view showing a part of an image forming apparatus according to a fourth embodiment of the present invention.
FIG. 9 is a longitudinal sectional front view showing a part of an image forming apparatus according to a fifth embodiment of the present invention.
FIG. 10 is a longitudinal sectional front view showing a part of an image forming apparatus according to a sixth embodiment of the present invention.
FIG. 11 is a longitudinal front view showing a part of an image forming apparatus according to a seventh embodiment of the present invention.
FIG. 12 is a longitudinal front view showing a part of an image forming apparatus according to an eighth embodiment of the present invention.
FIG. 13 is a perspective view illustrating a discharge product discharging structure from a discharge region in a conventional example.
[Explanation of symbols]
6 Photoconductor
9 Control gas generation means
11 Charging roller
14 Counter roller, airflow prevention member
16 Inlet
17 Flexible contact member
19 Brush
22 Upstream space
23 Downstream space
24 Exhaust port
32 Plate-like barrier, airflow prevention member
35 Second counter roller
37 Contact charging roller
38 Second inlet
39 cases
41 Exhaust flow path
43 Guide section
44 Second inlet
45 impeller
46 Swirl flow generating means
50 Static elimination means
51 Second counter roller

Claims (15)

The outer peripheral surface of the charged photoconductor is exposed to form an electrostatic latent image, toner is supplied to the photoconductor on which the electrostatic latent image has been formed to form a toner image, and the formed toner image is recorded. In an electrophotographic image forming apparatus that transfers to a medium, a charging roller that is disposed so as to face the outer peripheral surface of the photoconductor in a non-contact manner and rotates in a rotating direction with respect to the photoconductor, and an outer peripheral surface of the photoconductor A case that surrounds a part of the outer peripheral portion of the charging roller and an upstream side of the position facing the charging roller along a rotation direction of the photoconductor including a position facing the charging roller, and a surface airflow of the charging roller The charging roller is disposed so as to prevent entry into the case from the downstream side of the position facing the photoconductor along the rotation direction of the charging roller and to allow outflow of gas from the case to the outside of the case. Airflow obstruction A member, a control gas supply unit that supplies a control gas, and a control gas that is communicated with the control gas supply unit and is formed in the case. possess an inlet for substantially uniformly flows along the direction, and
Examples airflow blocking member, an electrophotographic image forming apparatus characterized that you have the counter roller is provided to counter rotate with respect to the charging roller so as to be parallel to disposed close to the charging roller. The outer peripheral surface of the charged photoconductor is exposed to form an electrostatic latent image, toner is supplied to the photoconductor on which the electrostatic latent image has been formed to form a toner image, and the formed toner image is recorded. In an electrophotographic image forming apparatus that transfers to a medium, a charging roller that is disposed so as to face the outer peripheral surface of the photoconductor in a non-contact manner and rotates in a rotating direction with respect to the photoconductor, and an outer peripheral surface of the photoconductor The upstream and downstream sides of the position facing the charging roller along the rotation direction of the photoconductor including the position facing the charging roller and the case surrounding the entire charging roller, and the surface airflow of the charging roller In the case, from the downstream space that is downstream of the position facing the charging roller along the rotation direction of the photoconductor, the upstream that is upstream of the position facing the charging roller along the rotation direction of the photoconductor Enter the side space An airflow blocking member disposed in the case so as to prevent gas from flowing into the downstream space from the upstream space, a control gas supply unit for supplying control gas, and the control A control gas is formed in the case so as to communicate the gas supply unit and the upstream space, and the control gas supplied from the control gas supply unit is substantially evenly distributed in the upstream space along the longitudinal direction of the photoconductor. an inlet for flowing, and an exhaust port formed in the casing to communicate with the downstream space possess,
Examples airflow blocking member, an electrophotographic image forming apparatus characterized that you have the counter roller is provided to counter rotate with respect to the charging roller so as to be parallel to disposed close to the charging roller. The outer peripheral surface of the charged photoconductor is exposed to form an electrostatic latent image, toner is supplied to the photoconductor on which the electrostatic latent image has been formed to form a toner image, and the formed toner image is recorded. In an electrophotographic image forming apparatus that transfers to a medium, a contact charging roller that is disposed in contact with the outer peripheral surface of the photoconductor and rotates in a rotating direction with respect to the photoconductor, and an outer surface of the photoconductor A case that surrounds the upstream and downstream sides of the contact charging roller along the rotation direction of the photosensitive member including the contact position of the contact charging roller and the entire contact charging roller, and a surface layer of the contact charging roller The upstream side of the contact position with the charging roller along the rotation direction of the photoconductor from the downstream space that is downstream of the contact position with the charging roller along the rotation direction of the photoconductor in the case Is An airflow blocking member disposed in the case so as to prevent the gas from flowing into the downstream space and to prevent the gas from flowing into the downstream space, and a control gas supply unit for supplying control gas And the control gas supply unit and the upstream space are formed in the case so that the control gas supplied from the control gas supply unit is introduced into the upstream space along the longitudinal direction of the photoconductor. A lower end side of the case with a gap that allows an external gas to enter the downstream space, and an inflow port that flows into the downstream space. possess a second inlet formed between the edge portion of the photosensitive member outer peripheral surface of the,
Examples airflow blocking member, an electrophotographic image forming apparatus characterized that you have the counter roller is provided to counter rotate with respect to the charging roller so as to be parallel to disposed close to the charging roller. 4. A flexible contact member that is in sliding contact with the outer peripheral surface of the photoconductor is provided at an edge of the case facing the upstream side in the rotation direction of the photoconductor. The electrophotographic image forming apparatus according to any one of the above . Before Symbol counter roller outer peripheral surface an electrophotographic image forming apparatus of any one described in claims 1, characterized in that it is租面processed fourth. An electrophotographic image forming apparatus according to any one of claims 1 to 5 the diameter of the counter roller is characterized by a smaller diameter than the diameter of the charging roller. An electrophotographic image forming apparatus according to any one of claims 1 to 4, characterized in that the brush on the outer peripheral surface of the counter roller is flocked. The outer peripheral surface of the charged photoconductor is exposed to form an electrostatic latent image, toner is supplied to the photoconductor on which the electrostatic latent image has been formed to form a toner image, and the formed toner image is recorded. In an electrophotographic image forming apparatus that transfers to a medium, a charging roller that is disposed so as to face the outer peripheral surface of the photoconductor in a non-contact manner and rotates in a rotating direction with respect to the photoconductor, and an outer peripheral surface of the photoconductor The upstream and downstream sides of the position facing the charging roller along the rotation direction of the photoconductor including the position facing the charging roller and the case surrounding the entire charging roller, and the surface airflow of the charging roller In the case, from the downstream space that is downstream of the position facing the charging roller along the rotation direction of the photoconductor, the upstream that is upstream of the position facing the charging roller along the rotation direction of the photoconductor Enter the side space An airflow blocking member disposed in the case so as to prevent gas from flowing into the downstream space from the upstream space, a control gas supply unit for supplying control gas, and the control A control gas is formed in the case so as to communicate the gas supply unit and the upstream space, and the control gas supplied from the control gas supply unit is substantially evenly distributed in the upstream space along the longitudinal direction of the photoconductor. An inflow port for inflow, and an exhaust port formed in the case in communication with the downstream space,
As the airflow prevention member, a plurality of plate-like members having one end close to and facing the outer peripheral surface of the charging roller and the other end facing the exhaust port are provided so as to form a flow path between adjacent plate-like members. that the image forming apparatus that electronic photographic method to said being.   The outer peripheral surface of the charged photoconductor is exposed to form an electrostatic latent image, toner is supplied to the photoconductor on which the electrostatic latent image has been formed to form a toner image, and the formed toner image is recorded. In an electrophotographic image forming apparatus that transfers to a medium, a contact charging roller that is disposed in contact with the outer peripheral surface of the photoconductor and rotates in a rotating direction with respect to the photoconductor, and an outer surface of the photoconductor A case that surrounds the upstream and downstream sides of the contact charging roller along the rotation direction of the photosensitive member including the contact position of the contact charging roller and the entire contact charging roller, and a surface layer of the contact charging roller The upstream side of the contact position with the charging roller along the rotation direction of the photoconductor from the downstream space that is downstream of the contact position with the charging roller along the rotation direction of the photoconductor in the case Is An airflow blocking member disposed in the case so as to prevent the gas from flowing into the downstream space and to prevent the gas from flowing into the downstream space, and a control gas supply unit for supplying control gas And the control gas supply unit and the upstream space are formed in the case so that the control gas supplied from the control gas supply unit is introduced into the upstream space along the longitudinal direction of the photoconductor. And an inflow opening that is formed in the case in communication with the downstream space, and a gap that allows gas from the outside to enter the downstream space. A second inlet formed between the edge and the outer peripheral surface of the photoreceptor,
  As the airflow prevention member, a plurality of plate-like members having one end close to and facing the outer peripheral surface of the charging roller and the other end facing the exhaust port are provided so as to form a flow path between adjacent plate-like members. An electrophotographic image forming apparatus.   The outer peripheral surface of the charged photoconductor is exposed to form an electrostatic latent image, toner is supplied to the photoconductor on which the electrostatic latent image has been formed to form a toner image, and the formed toner image is recorded. In an electrophotographic image forming apparatus that transfers to a medium, a charging roller that is disposed so as to face the outer peripheral surface of the photoconductor in a non-contact manner and rotates in a rotating direction with respect to the photoconductor, and an outer peripheral surface of the photoconductor The outer circumferential surface of the charging roller is covered with a gap of a predetermined dimension along which the surface airflow along the surface flows, and is positioned near the upstream side in the rotation direction of the photoconductor from the position where the photoconductor and the charging roller face each other A case in which an exhaust passage extending in a direction away from the photoconductor is formed, a control gas supply unit for supplying a control gas, and a control gas supplied from the control gas supply unit on the outer peripheral surface of the photoconductor Along the surface airflow An electrophotographic image forming apparatus and having a guide portion for guiding towards a position facing the said charging roller and.   The outer peripheral surface of the charged photoconductor is exposed to form an electrostatic latent image, toner is supplied to the photoconductor on which the electrostatic latent image has been formed to form a toner image, and the formed toner image is recorded. In an electrophotographic image forming apparatus that transfers to a medium, a contact charging roller that is disposed in contact with the outer peripheral surface of the photoconductor and rotates in a rotating direction with respect to the photoconductor, and an outer peripheral surface of the photoconductor The outer peripheral surface of the contact charging roller is covered with a gap of a predetermined dimension through which the surface airflow flows along, and is positioned nearer the upstream side in the rotation direction of the photoconductor than the contact position between the photoconductor and the contact charging roller. A case in which an exhaust passage extending in a direction away from the photoconductor is formed, a control gas supply unit that supplies a control gas, and a control gas supplied from the control gas supply unit As a surface airflow along the surface A guide portion that guides the photosensitive member and the contact charging roller toward the contact position, and gas from the outside is downstream along the rotation direction of the photosensitive member from the contact position of the photosensitive member and the contact charging roller. An electrophotographic image forming apparatus comprising: a second inlet formed between a lower end side edge of the case and an outer peripheral surface of the photosensitive member with a gap allowing entry into the side .   12. A swirling flow generating means is provided for generating a swirling flow over the entire area in the longitudinal direction of the photoconductor in the control gas supplied toward the outer peripheral surface of the photoconductor. The electrophotographic image forming apparatus described.   13. The electrophotographic image according to claim 12, wherein the swirling flow generating means includes a duct disposed in parallel with a longitudinal direction of the photosensitive member and an impeller disposed in the duct. Forming equipment.   The electrophotographic image forming apparatus according to any one of claims 10 to 13, wherein a neutralizing unit facing the outer peripheral surface of the photoconductor is provided in the guide portion.   12. The electrophotographic image forming apparatus according to claim 3, further comprising a second counter roller positioned at the second inlet and configured to rotate counter to the photosensitive member.

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