JP2006017974A - Electrostatic charging device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrostatic charging device with which electric discharge products can be efficiently discharged, in spite of miniaturization of an exhaust flow passage, the intrusion of an external additive to the interior of the electrostatic charging device is prevented, and proper images are obtainable. <P>SOLUTION: The electrostatic charging device 1 has a shielding plate 12 opened on one side and a corona discharge member 11 arranged within the shield plate 1, and electrostatically charges a photoreceptor drum 2 arranged on the aperture side of the shielding plate 12. The electrostatic charging device 1 has a first contact seal 21 which is provided on the upstream side in the moving direction of the photoreceptor drum 2 in the shielding plate 12 and comes into contact with the photoreceptor drum 2 and a second contact seal 22, which is provided on the downstream in the moving direction of the photoreceptor drum 2 in the shielding plate 12 and comes into contact with the photoreceptor drum 2, wherein the contact angle θ 1 of the first contact seal 21, with respect to the photoreceptor drum 2 is greater than the contact angle θ 2 of the second contact seal 22 with respect to the photoreceptor drum 2. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a charging device used in an image forming apparatus. More specifically, the present invention relates to a charging device using a corona discharge member.

  Conventionally, as a charging device for uniformly charging a photosensitive drum of an image forming apparatus, there is one using a corona discharge member. In such a charging device, discharge products such as ozone and NOx are generated by discharge, and it is necessary to appropriately treat them and exhaust them to the outside. Therefore, a duct for exhaust is arranged around the charging device, and an appropriate air flow is formed by a fan.

For example, in the charging device described in Patent Document 1, air circulation holes are provided in the ceiling wall of a gate-shaped shield member surrounding the discharge wire. Further, a duct is installed so as to surround the shield member and the discharge wire, and an ozone filter is disposed in the duct. A fan is connected to the downstream side of the duct, and an air flow in a direction perpendicular to the discharge wire is formed.
JP-A-6-289692

  However, in the conventional charging device described above, it is necessary to form a duct for exhaust along with the charging device, and a large fan capable of forming an exhaust flow from the entire axial length of the charging device is required. It was. For this reason, the image forming apparatus tends to increase in size as a whole. In contrast, it has been desired to reduce the size of fans and ducts by exhausting along the axial direction of the charging device. However, if the fan is downsized and exhausted in the axial direction of the charging device, the exhaust power will be greatly reduced, particularly at locations far from the fan.

  Therefore, in order to prevent air leakage between the photosensitive drum and the charging device, it is conceivable to close the gap between the shielding member of the charging device and the photosensitive drum with a sealing member or the like. However, the external additive that has passed through the cleaning device disposed upstream of the charging device may adhere to the photosensitive drum, and the external additive is scraped off by the downstream one of the seal members. In such a case, the scraped external additive may enter the inside of the charging device. When the external additive enters the charging device, the charging potential rises above a predetermined voltage, causing image noise.

  The present invention has been made to solve the problems of the conventional charging device described above. That is, the problem is that the discharge product can be discharged efficiently even if the exhaust passage is downsized, and the external additive can be prevented from entering the charging device, and a good image can be obtained. It is to provide a charging device.

  In order to solve this problem, the charging device of the present invention includes a shield member having one opening and a discharge electrode disposed in the shield member, and charges a photosensitive member located on the opening side of the shield member. The charging device is provided on the upstream side of the shield member in the moving direction of the photoconductor, and is provided on the downstream side of the shield member in the moving direction of the photoconductor, and is in contact with the photoconductor. A contact angle of the first seal with respect to the photosensitive member is larger than a contact angle of the second seal with respect to the photosensitive member.

  According to the charging device of the present invention, the space between the shield member covering the three sides of the discharge electrode and the photosensitive member is closed by the first seal and the second seal. Therefore, since the exhaust can be efficiently performed in the axial direction of the charging device, the exhaust flow path can be reduced in size. Furthermore, in the present invention, the contact angle of the first seal provided on the upstream side in the moving direction of the photoconductor with respect to the photoconductor is larger than that of the second seal on the downstream side. The surface of can be strongly scraped off. That is, the first seal is stronger than the second seal in scraping off the material adhering to the surface of the photoreceptor (for example, an external additive). Therefore, external additives and the like are often scraped off by the first seal, and those not scraped off by the first seal are not scraped off by the second seal. Since the external additive or the like scraped off by the first seal on the upstream side falls to the outside of the charging device, the penetration of the external additive into the charging device is well prevented. As a result, the discharge product can be discharged efficiently even if the exhaust passage is reduced in size, and the charging device can prevent a foreign additive from entering the charging device and obtain a good image. Yes.

  The charging device of the present invention is a charging device that has a shield member that is open on one side and a discharge electrode disposed in the shield member, and charges a photoreceptor located on the opening side of the shield member, A first seal provided on the upstream side in the moving direction of the photoconductor on the shield member and contacting the photoconductor; and a second seal provided on the downstream side in the moving direction of the photoconductor on the shield member and contacting the photoconductor. The protrusion length X of the first seal from the shield member is the shortest distance A between the upstream side of the shield member and the photosensitive member, and the photosensitive member in the direction extending the upstream side of the shield member toward the photosensitive member. The distance B is within the range of A <X ≦ B, and the protrusion length Y of the second seal from the shield member extends in the direction in which the downstream side of the shield member extends parallel to the upstream side toward the photoreceptor. Between the body C to, or may be a relationship of Y> C.

  In such a case, the protruding length of the first seal on the upstream side is set to such a length that the tip portion slightly touches the surface of the photoreceptor. Therefore, even if the first seal is attracted by the frictional force with the surface of the photoreceptor, the contact angle is kept large. On the other hand, the projecting length of the second seal is sufficiently long and contacts the surface of the photoreceptor in a large range. Therefore, the contact angle of the second seal becomes small. Therefore, the scraping force of the first seal is large and the scraping force of the second seal is small.

Further, in the present invention, it is preferable that a downstream means for directing the first seal toward the downstream side in the moving direction of the photosensitive member is provided.
In this way, since the first seal is directed downstream from the surface of the photosensitive member from the beginning, it does not contact the surface of the photosensitive member in the counter direction, and there is no fear of damaging the surface of the photosensitive member. As the downstream means, for example, a bending member provided at a joint portion between the first seal and the shield member may be used. Alternatively, the axial end of the first seal may be fixed to another member such as a holder or an end seal. Even if the end part is greatly directed to the downstream side, the central part comes into contact with a large contact angle due to the elasticity of the seal. A large contact angle may be obtained in the image forming area of the photoreceptor.

The charging device of the present invention is a charging device that has a shield member that is open on one side and a discharge electrode disposed in the shield member, and charges a photoreceptor located on the opening side of the shield member, A first seal provided on the upstream side of the shield member in the moving direction of the photosensitive member and in contact with the photosensitive member; and a second seal provided on the downstream side of the shield member in the moving direction of the photosensitive member and in contact with the photosensitive member. The contact pressure of the first seal with respect to the photosensitive member may be larger than the contact pressure of the second seal with respect to the photosensitive member.
A difference in the scraping force between the first seal and the second seal can also be provided by the difference in contact pressure. Here, the contact pressure is related to Young's modulus, sheet thickness, free length, and bite amount. The higher the Young's modulus, the thicker the sheet, the shorter the free length, and the greater the amount of bite, the greater the contact pressure.

The charging device of the present invention is a charging device that has a shield member that is open on one side and a discharge electrode disposed in the shield member, and charges a photoreceptor located on the opening side of the shield member, A first seal provided on the upstream side of the shield member in the moving direction of the photosensitive member and in contact with the photosensitive member; and a second seal provided on the downstream side of the shield member in the moving direction of the photosensitive member and in contact with the photosensitive member. The friction coefficient of the first seal with respect to the photosensitive member may be larger than the friction coefficient of the second seal with respect to the photosensitive member.
A difference in the scraping force between the first seal and the second seal can also be provided depending on the difference in the friction coefficient.

The charging device of the present invention is a charging device that has a shield member that is open on one side and a discharge electrode disposed in the shield member, and charges a photoreceptor located on the opening side of the shield member, A first seal that is provided on the upstream side of the shield member in the moving direction of the photoconductor and contacts the photoconductor; a second seal that is provided on the downstream side of the shield member in the moving direction of the photoconductor and that contacts the photoconductor; It may have an accommodating part for accommodating what is scraped off from the photoconductor, adjacent to the upstream side in the moving direction of the photoconductor with respect to the seal.
If it is such, the external additive etc. which were scraped off by the 2nd seal | sticker are accommodated in an accommodating part. Therefore, it is possible to prevent the external additive from entering the charging device.

Further, in the present invention, (1) a receiving member that does not contact the photoconductor is provided upstream of the second seal in the moving direction of the photoconductor, and (2) the downstream side of the photoconductor in the moving direction of the shield member is the second seal. Either at the front end side of the mounting position of the photosensitive member, bent in the upstream direction of the photosensitive member movement direction, or (3) having a receiving plate on the inner surface of the shield member on the downstream side of the photosensitive member movement direction. It is desirable to be configured.
For example, if the receiving member (1) is provided, the space between the second seal and the receiving member can be used as the accommodating portion. Moreover, if it is made like (2), it can be set as a accommodating part between a front end side and a 2nd seal | sticker from the bending position of a shield member. Moreover, if it has the accommodation plate of (3), it can be set as an accommodating part between an accommodation plate and a shield member.

The charging device of the present invention is a charging device that has a shield member that is open on one side and a discharge electrode disposed in the shield member, and charges a photoreceptor located on the opening side of the shield member, A first seal provided on the upstream side of the shield member in the moving direction of the photosensitive member and in contact with the photosensitive member; a second seal provided on the downstream side of the shield member in the moving direction of the photosensitive member and in contact with the photosensitive member; It may be provided upstream of the seal in the moving direction of the photoconductor, and may have a conductive member that is in contact with the photoconductor and to which a voltage is applied.
In this way, the external additive attached to the photoconductor first comes into contact with the conductive member. Therefore, if an appropriate voltage is applied to the conductive member, the adhesive force between the external additive and the photoreceptor can be weakened. The external additive whose adhesion is weakened is easily scraped off by the first seal.

  According to the charging device of the present invention, it is possible to efficiently discharge discharge products even when the exhaust flow path is downsized, and to prevent external additives from entering the charging device, thereby obtaining a good image. be able to.

"First form"
Hereinafter, a first embodiment of the present invention will be described in detail with reference to the accompanying drawings. In this embodiment, the photosensitive drum is uniformly charged, and the present invention is applied to a charging device using a corona discharge member.

  As shown in FIG. 1, the charging device 1 of this embodiment is disposed along the axial direction so as to face the photosensitive drum 2. Further, a duct 3 and a fan 4 are connected to the outside of the charging device 1 so that an air flow flowing in the axial direction in the charging device 1 can be formed as indicated by an arrow in the figure. A filter or the like for appropriately treating discharge products such as ozone can be provided in front of the fan 4.

  As shown in FIGS. 1 and 2, the charging device 1 includes a corona discharge member 11, a shield plate 12, and a control electrode 13, which are held by a holder 14. Furthermore, the corona discharge member 11 and the shield plate 12 are connected to power sources 15 and 16 and a voltage is appropriately applied. FIG. 2 is a cross-sectional view of the main part near the center in the left-right direction in FIG.

  The corona discharge member 11 is a discharge wire having a sawtooth outer shape. The shield plate 12 is a U-shaped member that covers the corona discharge member 11 from three sides not facing the photosensitive drum 2. Then, both end portions of the shield plate 12 in the axial direction are open ends so that air can flow. Here, as shown in FIG. 2, a shield plate 12 having a different cross-sectional shape on the left and right in the drawing is used. The right end in FIG. 2, that is, the upstream end with respect to the rotation direction of the photosensitive drum 2, is formed by a plane parallel to a plane including the corona discharge member 11 and the center of the photosensitive drum 2. In addition, on the downstream side on the left in the figure, the tip is bent inward. The control electrode 13 is a grid electrode for controlling the charging potential of the photosensitive drum 2 to a predetermined potential, and covers the opening on the photosensitive drum 2 side of the shield plate 12.

  Since a predetermined interval is provided between the photosensitive drum 2 and the shield plate 12 or the control electrode 13, in order to ensure that the airflow flows through the duct 3, air leakage from the gap here is prevented. There is a need to. Therefore, seals for closing the gaps are provided on the four sides surrounding the control electrode 13 of the shield plate 12. Specifically, a first contact seal 21 and a second contact seal 22 are attached along the axial direction of the shield plate 12, and end seals 23 and 23 are provided at both ends in the axial direction. Each of these seals 21, 22 and 23 is held in a state where one side is fixed to the shield plate 12 and the other side is in contact with the photosensitive drum 2, thereby preventing air from flowing therethrough. Yes.

  The first contact seal 21 is disposed on the upstream side with respect to the rotation direction of the photosensitive drum 2 and is formed, for example, of polyurethane or the like in a sheet shape having a thickness of about 100 to 200 μm. The second contact seal 22 is disposed on the downstream side with respect to the rotation direction of the photosensitive drum 2 and is formed, for example, of polyurethane or the like in a sheet shape having a thickness of about 20 to 80 μm. The 1st contact seal 21 and the 2nd contact seal 22 should just be a sheet | seat which has not only polyurethane but moderate elasticity. Further, the end seals 23 and 23 are made of polyurethane or the like in a block shape, and the upper surface in FIG. 1 is in contact with the photosensitive drum 2. Any of these seals can also be formed of a foam.

  As shown in FIG. 3, the first contact seal 21 is formed such that the width X extending upward in the drawing from the shield plate 12 falls within the following range. From the shortest distance A between the right end position of the shield plate 12 and the photosensitive drum 2, and the right end position of the shield plate 12 and the distance B from the right end position extending straight upward in the figure to the position where it intersects the photosensitive drum 2. , A <X ≦ B. On the other hand, the width Y of the second contact seal 22 protruding upward in the figure from the shield plate 12 extends from the left end position of the shield plate 12 to the position where it extends straight upward in the figure and intersects the photosensitive drum 2. It is larger than the distance C and Y> C.

  By doing so, the first contact seal 21 and the second contact seal 22 flutter in the same direction as the rotation direction (trailing direction) by the frictional force with the surface of the photosensitive drum 2, and are shown in FIG. As described above, the front end portions thereof contact the surface of the photosensitive drum 2 at different angles. Hereinafter, the angle formed between the front end of each seal and the tangent line of the photosensitive drum 2 at the position where the seal is in contact is referred to as the contact angle of the seal. By setting the width as described above, the contact angle θ1 of the first contact seal 21 is larger than the contact angle θ2 of the second contact seal 22.

  Next, the operation of the charging device 1 of this embodiment will be described. The charging device 1 is used by being incorporated in an electrophotographic image forming apparatus. During the image forming operation, voltages are applied from the power sources 15 and 16 to the corona discharge member 11 and the shield plate 12, and a grid voltage is applied to the control electrode 13. Thereby, a discharge is generated from the corona discharge member 11, and the surface of the photosensitive drum 2 is uniformly charged to a predetermined potential. Further, the fan 4 is driven, and discharge products such as ozone generated by the discharge are discharged through the duct 3.

  Here, as described in the section “Problems to be Solved by the Invention”, the surface of the photosensitive drum 2 may have external additives that could not be cleaned by the previous cleaning device. The external additive moves with the rotation of the photosensitive drum 2 and faces the charging device 1. However, it is desired to prevent the external additive from entering the shield plate 12. For this purpose, it is desirable to scrape off the external additive as much as possible at the position of the first contact seal 21 and not to scrape off the external additive at the position of the second contact seal 22.

  In the charging device 1 of the present embodiment, the first contact seal 21 is formed of a thicker member than the second contact seal 22, so the first contact seal 21 is harder and its scraping force is higher than that of the second contact seal 22. large. That is, the external additive that has not been scraped off by the first contact seal 21 is not scraped off by the second contact seal 22. The external additive scraped off by the first contact seal 21 does not enter the shield plate 12 and is appropriately processed outside the shield plate 12. On the other hand, even if there is an external additive that has passed through the first contact seal 21, the second contact seal 22 is made thinner and softer than the first contact seal 21, so that it passes without being scraped off by the second contact seal 22. Therefore, there is no possibility that the external additive enters the shield plate 12.

  Furthermore, in this embodiment, since the width X of the first contact seal 21 is set as described above, scraping of the external additive at the first contact seal 21 is further ensured. Such a contact seal is in the trailing direction by a frictional force according to the rotational drive of the photosensitive drum 2. Further, such a seal causes permanent distortion in a low-temperature and low-humidity environment (for example, an air temperature of 10 ° C. and a relative humidity of 15%), so that the scraping force is particularly reduced when the contact angle is small. Since the width X of the first contact seal 21 is in the range of A <X ≦ B, the contact angle is kept large even in the trailing direction, and the scraping force even when permanent distortion occurs. Is hardly reduced. On the other hand, since the width Y of the second contact seal 22 satisfies Y> C, the contact angle is small and the scraping force is small.

  Further, in order to ensure the trailing direction, as shown in FIG. 4, a bending member 25 may be further provided to bend the first contact seal 21 leftward in the figure. This is because it is not preferable that the hard first contact seal 21 is in contact with the photosensitive drum 2 in the counter direction because it causes damage to the surface of the photosensitive drum 2. By providing the bending member 25, the direction of the distal end direction of the first contact seal 21 can be guided to ensure the trailing direction. The bending member 25 does not necessarily need to be provided over the entire axial direction, and it is sufficient if the bending member 25 is provided at both ends or two to three places as appropriate.

  Alternatively, as shown in FIG. 5, the length of the first contact seal 21 in the axial direction (left-right direction in FIG. 1) is increased, and both ends are attached to the surface of the holder 14 or the end seal 23. It may be. If the end is bent as described above, the trailing direction is sequentially reached from the end by the rotation of the photosensitive drum 2.

  Here, the thicknesses of the first contact seal 21 and the second contact seal 22 are different from each other. However, in order to provide a difference in the scraping force between the first contact seal 21 and the second contact seal 22. In addition, the following method is also possible. If the scraping force of the second contact seal 22 is sufficiently small compared to the scraping force of the first contact seal 21, external additives that have not been scraped off by the first contact seal 21 are scraped off by the second contact seal 22. Therefore, there is no possibility that the external additive adheres to the inside of the shield plate 12.

For example, a member having a lower contact pressure than the first contact seal 21 may be used as the second contact seal 22. This contact pressure F can be expressed by the following equation, where Young's modulus E, sheet thickness t, free length L, and amount of biting Δ into the photosensitive drum 2.
F = E × t ³ ÷ (4 × L ³ ) × Δ
Therefore, it is possible to provide a difference in the contact pressure F between the first contact seal 21 and the second contact seal 22 by using not only the above-described sheet thickness but also a material having a different Young's modulus or changing the free length. it can.

  Alternatively, a material having a smaller coefficient of friction than the first contact seal 21 may be used for the second contact seal 22. For example, a polyurethane sheet is used for the first contact seal 21, and a material having a smaller friction coefficient than polyurethane such as PTFE, ETFE, PFA, and PI is used for the second contact seal 22. This also makes it possible to provide a difference in the scraping force between the first contact seal 21 and the second contact seal 22.

  As described in detail above, according to the charging device 1 of this embodiment, the shield plate 12 and the photosensitive drum 2 are surrounded by the first contact seal 21, the second contact seal 22, and the end seals 23, 23. It is blocked. Therefore, the discharge product in the shield plate 12 is surely exhausted by the air flow caused by the fan 4. Further, the first contact seal 21 is formed of a thicker member than the second contact seal 22 and contacts the photosensitive drum 2 with a large contact angle. Accordingly, the external additive adhering to the photosensitive drum 2 is almost scraped off by the first contact seal 21 and is not scraped off by the second contact seal 22. This prevents the external additive from entering the shield plate 12 of the charging device 1. Therefore, the charging device 1 can efficiently discharge discharge products even if the exhaust flow path is downsized, and prevents an external additive from entering the shield plate 12 to obtain a good image. It has become.

"Second form"
Next, a second embodiment of the present invention will be described in detail with reference to the accompanying drawings. The charging device 30 of this embodiment is different from the charging device 1 of the first embodiment only in the contact seal portion, and the other portions are common, so the common portions are denoted by the same reference numerals and description thereof is omitted. .
In the charging device 30 of this embodiment, in addition to the charging device 1 of the first embodiment, even if the external additive is scraped off by the second contact seal 22, the scraped external additive is removed from the shield plate 12. Is provided with a receiving portion S that is received so as not to enter.

  As shown in FIG. 6, the charging device 30 according to this embodiment includes a sheet member 31 between the second contact seal 22 and the shield plate 12. As the sheet member 31, for example, a PET sheet having a thickness of 0.1 mm is used and is not in contact with the photosensitive drum 2. The sheet member 31 is affixed to the shield plate 12 and is fixed to the second contact seal 22 by an adhesive 32 that also serves as a spacer. Accordingly, a substantially triangular accommodating portion S is formed between the second contact seal 22 and the sheet member 31 on the upstream side of the second contact seal 22.

  According to the charging device 30, even if the external additive that could not be scraped off by the first contact seal 21 is scraped off by the second contact seal 22, it is received by the sheet member 31 and stored in the storage portion S. Therefore, the external additive scraped by the second contact seal 22 is prevented from entering the shield plate 12.

Further, the charging device 30 of this embodiment may be configured as shown in FIG. That is, the upper left end of the shield plate 12 in the drawing is extended to form the extended surface 33, and the bonding position between the second contact seal 22 and the shield plate 12 is set to be lower in the drawing than the extended surface 33. Even in this case, the accommodating portion S is formed between the second contact seal 22 and the extended surface 34.
Alternatively, the charging device 30 of this embodiment may be as shown in FIG. That is, you may make it provide the accommodating board 34 which comprises the accommodating part S along the inner wall of the shield board 12. As shown in FIG.

  As described above in detail, the charging device 30 of the present embodiment can discharge discharge products efficiently even if the exhaust passage is downsized, as in the charging device 1 of the first embodiment. The charging device 30 prevents the external additive from entering the charging device 30 and obtains a good image.

"Third form"
Next, a third embodiment of the present invention will be described in detail with reference to the accompanying drawings. The charging device 40 of the present embodiment is different from the charging device 1 of the first embodiment only in the contact seal portion, and the other portions are common, so the common portions are denoted by the same reference numerals and description thereof is omitted. .
The charging device 40 according to the present embodiment further ensures the scraping of the external additive at the first contact seal 21 in addition to the charging device 1 according to the first embodiment.

  As shown in FIG. 9, the charging device 40 of this embodiment is provided with a third seal 41 on the upstream side of the first contact seal 21. The tip of the third seal 41 is in contact with the photosensitive drum 2 and is connected to a power source 42 to apply a voltage. The third seal 41 has conductive particles such as carbon dispersed on the surface of a sheet of polyurethane, soft polyamide, polyester, ETFE, PTFE, PFA, PI, etc., and has a thickness of 50 to 200 μm and an electric resistance of 10 The third power to the eighth power Ω / □. A voltage equal to or higher than the discharge start voltage is applied to the photosensitive drum 2 by the power source 42. For example, it is desirable to set it to about -500V to -1000V.

  In general, the external additive adhering to the photosensitive drum 2 is relatively strongly connected to the photosensitive drum 2 by a Coulomb force or a mirror image force. According to the charging device 40, the external additive is charged to a predetermined polarity by the voltage applied to the third seal 41 by touching the third seal 41. Thereby, the adhesion force between the photosensitive drum 2 and the external additive is reduced. The external additive having a reduced adhesive force is easily scraped off by the first contact seal 21. In addition, the external additive scraped off by the first contact seal 21 falls from a gap provided between the first contact seal 21 and the third seal 41 and is appropriately processed outside the shield plate 12.

  The charging device 40 may be as shown in FIG. Instead of connecting the power source 42 to the third seal 41, a slightly wider third seal 43 may be used and one end thereof may be attached to the shield plate 12. At this time, by using a conductive double-sided tape or the like as the adhesive member, a voltage can be applied to the third seal 43 by the power supply 16 connected to the shield plate 12. The voltage applied to the shield plate 12 by the power supply 16 at the time of image formation may be outside the range of the voltage to be applied to the third seal 43. In this case, the voltage is applied at a predetermined timing during non-image formation. Alternatively, a predetermined voltage may be applied.

  Further, when the third seal 43 is attached to the shield plate 12 or the first contact seal 21 in this way, the lower end of the third seal 43 is preferably serrated as shown in FIG. Then, only the sawtooth tip 43a is pasted. In this way, the external additive that has fallen into the space between the first contact seal 21 and the third seal 43 can be dropped to the outside through the gap between the saw teeth, There is no accumulation between the third seal 43. The shape of the lower end portion is not limited to the sawtooth shape, and any shape can be used as long as a hole for dropping the external additive can be formed on the upper portion of the pasted portion.

  The voltage applied to the third seals 41 and 43 is more effective when applied by adding a vibration voltage to the DC voltage. In FIGS. 9 and 10, the third seals 41 and 43 are brought into contact with the photosensitive drum 2 in the trailing direction, but may be in the counter direction.

  As described in detail above, the charging device 40 of this embodiment can discharge discharge products efficiently even if the exhaust passage is downsized, as in the charging device 1 of the first embodiment. The charging device 40 prevents the external additive from entering the charging device and obtains a good image.

In addition, this form is only a mere illustration and does not limit this invention at all. Therefore, the present invention can naturally be improved and modified in various ways without departing from the gist thereof.
For example, the shape of the shield plate 12, the arrangement with respect to the photosensitive drum 2, the shape of the holder 14 and the duct 3, and the like can be changed as appropriate.

It is a schematic explanatory drawing which shows the whole charging device. It is sectional drawing which shows the charging device of a 1st form. It is explanatory drawing which shows the magnitude | size of the 1st contact seal and 2nd contact seal which are used for the charging device of a 1st form. It is sectional drawing which shows the charging device of a 1st form. It is explanatory drawing which shows how to attach the 1st contact seal used for the charging device of a 1st form. It is sectional drawing which shows the charging device of a 2nd form. It is sectional drawing which shows the charging device of a 2nd form. It is sectional drawing which shows the charging device of a 2nd form. It is sectional drawing which shows the charging device of the 3rd form. It is sectional drawing which shows the charging device of the 3rd form. It is explanatory drawing which shows the shape of the 3rd seal | sticker used for the charging device of a 3rd form.

Explanation of symbols

1, 30, 40 Charging device 2 Photosensitive drum (photosensitive member)
11 Corona discharge member (discharge electrode)
12 Shield plate (shield member)
14 Holder (Means for downstream)
21 First contact seal (first seal)
22 Second contact seal (second seal)
23 End seal (means for downstream)
25 Bending members (downstream means)
31 Sheet member (receiving member)
34 Housing plate 41, 43 Third seal (conductive member)
S accommodating part

Claims (8)

In a charging device that has a shield member that is open on one side, and a discharge electrode that is disposed in the shield member, and charges a photoreceptor located on the opening side of the shield member.
A first seal provided on the upstream side of the shield member in the moving direction of the photosensitive member and contacting the photosensitive member;
A second seal that is provided on the downstream side of the shield member in the moving direction of the photoconductor and contacts the photoconductor;
The charging device according to claim 1, wherein a contact angle of the first seal with respect to the photosensitive member is larger than a contact angle of the second seal with respect to the photosensitive member. In a charging device that has a shield member that is open on one side, and a discharge electrode that is disposed in the shield member, and charges a photoreceptor located on the opening side of the shield member.
A first seal provided on the upstream side of the shield member in the moving direction of the photosensitive member and contacting the photosensitive member;
A second seal that is provided on the downstream side of the shield member in the moving direction of the photoconductor and contacts the photoconductor;
The protrusion length X of the first seal from the shield member is the shortest distance A between the upstream side of the shield member and the photoconductor, and the photosensitivity in the direction in which the upstream side of the shield member extends toward the photoconductor. Within the range of A <X ≦ B with respect to the distance B from the body,
The relationship Y> C with respect to the distance C between the protrusion length Y of the second seal from the shield member and the photosensitive member in the direction in which the downstream side of the shield member extends parallel to the upstream side toward the photosensitive member A charging device. The charging device according to claim 2,
A charging device, characterized in that downstream means for directing the first seal toward the downstream side in the moving direction of the photosensitive member is provided. In a charging device that has a shield member that is open on one side, and a discharge electrode that is disposed in the shield member, and charges a photoreceptor located on the opening side of the shield member.
A first seal provided on the upstream side of the shield member in the moving direction of the photosensitive member and contacting the photosensitive member;
A second seal that is provided on the downstream side of the shield member in the moving direction of the photoconductor and contacts the photoconductor;
The charging device according to claim 1, wherein a contact pressure of the first seal with respect to the photosensitive member is larger than a contact pressure of the second seal with respect to the photosensitive member. In a charging device that has a shield member that is open on one side, and a discharge electrode that is disposed in the shield member, and charges a photoreceptor located on the opening side of the shield member.
A first seal provided on the upstream side of the shield member in the moving direction of the photosensitive member and contacting the photosensitive member;
A second seal that is provided on the downstream side of the shield member in the moving direction of the photoconductor and contacts the photoconductor;
The charging device according to claim 1, wherein a friction coefficient of the first seal with respect to the photosensitive member is larger than a friction coefficient of the second seal with respect to the photosensitive member. In a charging device that has a shield member that is open on one side, and a discharge electrode that is disposed in the shield member, and charges a photoreceptor located on the opening side of the shield member.
A first seal provided on the upstream side of the shield member in the moving direction of the photosensitive member and contacting the photosensitive member;
A second seal provided on the downstream side of the shield member in the moving direction of the photosensitive member and contacting the photosensitive member;
A charging device comprising: an accommodation portion for accommodating a material scraped off from the photosensitive member adjacent to the second seal on the upstream side in the moving direction of the photosensitive member. The charging device according to claim 6, wherein the housing portion is
(1) A receiving member that does not contact the photoconductor is provided upstream of the second seal in the moving direction of the photoconductor.
(2) The downstream side of the shield member in the moving direction of the photosensitive member is bent toward the upstream side of the moving direction of the photosensitive member at a position closer to the tip side than the attachment position of the second seal.
(3) having a receiving plate on the inner surface of the shield member on the downstream side in the moving direction of the photosensitive member;
A charging device comprising any of the above. In a charging device that has a shield member that is open on one side, and a discharge electrode that is disposed in the shield member, and charges a photoreceptor located on the opening side of the shield member.
A first seal provided on the upstream side of the shield member in the moving direction of the photosensitive member and contacting the photosensitive member;
A second seal provided on the downstream side of the shield member in the moving direction of the photosensitive member and contacting the photosensitive member;
A charging device, comprising: a conductive member provided upstream of the first seal in the moving direction of the photosensitive member and contacting the photosensitive member and to which a voltage is applied.

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