JP2006106453A - Electrifying device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrifying device capable of restraining image noise caused by an ion current with compact constitution. <P>SOLUTION: The electrifying device 100 has a discharge electrode 11, a seal member 12 sliding in contact with a photoreceptor drum 10, a control electrode 13 positioned between the discharge electrode 11 and the photoreceptor drum 10, a pair of shielding plates 14 opposed while putting the discharge electrode 11 in between, and a housing member 16 in which they are housed. The electrifying device 100 is provided with a gap between the shielding plate 14 and the housing member 16, whereby the ion current generated by the discharge of the discharge electrode 11 to the photoreceptor drum 10 circulates in the electrifying device 100. Then, an ozone removing member 15 is arranged in a path where the ion current circulates. Activated carbon, for example, is mentioned as material for removing ozone. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a charging device used in an electrophotographic image forming apparatus (for example, a copying machine or a printer). More specifically, the present invention relates to a charging device using a corona discharge member.

  As a charging device for uniformly charging an image carrier such as a photosensitive drum of an image forming apparatus, there is one using a corona discharge member. In such a charging device, an air stream (ion stream) containing ozone is generated from the vicinity of the corona discharge member due to discharge on the surface of the image carrier. This ion flow contributes to image noise such as a decrease in image density and blurring. In order to solve this problem, in the conventional charging device, for example, an exhaust duct is arranged around the charging device, an air flow is formed by a fan or the like, and an ozone adsorbent or the like is provided in the vicinity of the fan. Proper exhaust was done.

Examples of technical literature focusing on the problem of ion flow include the following. In the charging device described in Patent Document 1, it is said that by providing an ozone decomposition catalyst on the discharge electrode plate, it is possible to provide a corona charging device in which ozone is decomposed satisfactorily and image distortion is small. Further, in the charging device described in Patent Document 2, stable image formation can be performed by applying an ozone adsorbent to the shield plate. Patent Document 3 discloses a corona charger in which a duct for exhausting an ion flow is disposed and an ozone absorbing resin is disposed at a downstream position of the ion flow.
JP-A-10-90974 JP 2001-331021 A JP-A-8-160715

  However, these charging devices have the following problems. That is, in any charging device, it is necessary to arrange a duct for exhausting in order to exhaust ozone properly. Furthermore, it is necessary to create an appropriate air flow by the fan. For this reason, it has been very difficult to cope with cost reduction and compactness that have been requested in recent years.

  The present invention has been made to solve the problems of the conventional charging device described above. That is, an object of the present invention is to provide a charging device that suppresses image noise due to ion flow and an image forming apparatus including the charging device with a compact configuration.

  A charging device designed to solve this problem is a charging device that charges an image carrier by corona discharge, and accommodates a discharge electrode, a pair of stabilizer plates facing each other across the discharge electrode, and a stabilizer plate. In addition, a housing member having an opening on the surface facing the image carrier, a seal member attached to the housing member for sealing a gap between the image carrier and the housing material, and a gap between the housing member and the stabilizer And an ozone removing member for removing ozone.

  That is, in the charging device of the present invention, an ion flow circulation path is formed by the stabilizing plate surrounding the discharge electrode and the housing member surrounding the stabilizing plate. That is, the ion flow generated during discharge collides with the image carrier and is dispersed. The dispersed ion flow is prevented from flowing out to the outside by the seal member, and propagates through the gap between the housing member and the stabilization plate that is generated when the housing member covers the stabilization plate. Thereafter, the ion flow collides with the bottom surface of the housing member and flows again between the stabilizing plates. That is, the ion flow generated by the discharge circulates in the charging device.

  In the charging device of the present invention, the ozone removing member is disposed in the gap between the housing member and the stabilizing plate. That is, an ozone removing member is arranged in the circulation path of the ion flow. Examples of the ozone removing member include those obtained by applying a material (activated carbon or the like) that adsorbs or decomposes ozone to an insulating film, and those obtained by kneading and molding the ozone removing material. Thereby, when the ion flow passes through the gap between the housing member and the stabilizer, ozone in the ion flow is appropriately processed, and as a result, image noise is suppressed.

  The housing member is preferably made of an insulating material. That is, when the housing member is made of a conductive material, an electric field is formed between the stable plate made of the conductive material and the flow of the ion flow becomes unstable. Therefore, by using a housing member made of an insulating material (for example, ABS resin), it is possible to reliably circulate the ion flow.

  Further, it is better that the discharge electrode is a sawtooth electrode. That is, corona discharge with directivity can be performed by making the discharge electrode into a sawtooth shape. Therefore, an ion flow can be generated more reliably, and as a result, ozone can be easily removed.

  In the charging device of the present invention, it is preferable that a plurality of grooves are provided on the outer wall of the stabilizer and the inner wall of the housing member. That is, by providing a plurality of grooves on these wall surfaces, the ion flow flowing through the gaps meanders. Therefore, the contact area between the ion flow and the ozone removing member is increased, and ozone can be more efficiently removed.

  Further, the ozone removing member of the charging device of the present invention is a stepped member, and it is better that the stepped portion is provided on the upstream side in the ion flow propagation direction. Or it is good also as what has the structure which piled up the shaping | molding member from which a shape differs with respect to the propagation direction of an ion flow. Even with such a structure, the contact area between the ion flow and the ozone removing member is increased, and ozone can be more efficiently removed.

  In the charging device of the present invention, an ion flow circulation path is provided in the charging device. Furthermore, ozone is appropriately reduced by providing an ozone removing member in the circulation path of the ion flow. That is, proper treatment of ozone is achieved without providing a duct or a fan. Therefore, a charging device is provided that has a compact configuration and suppresses image noise due to ion flow.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the best mode for embodying 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.

[First embodiment]
FIG. 1 shows a schematic configuration of a charging device 100 according to the first embodiment. FIG. 2 shows an image of the XX cross section of the charging device 100 shown in FIG. 1 and shows a state when the charging device 100 is opposed to the photosensitive drum 10. FIG. 3 shows a state before the charging device 100 shown in FIG. 1 is combined. The charging device 100 is used by being incorporated in an electrophotographic image forming apparatus.

  As shown in FIG. 1, the charging device 100 according to the first embodiment includes a discharge electrode 11, a seal member 12, a control electrode 13, a shield plate 14, an ozone removing member 15, and a housing member 16 that accommodates them. Yes. As shown in FIG. 2, the charging device 100 faces the photosensitive drum 10 and is disposed along the axial direction of the photosensitive drum 10. Further, the discharge electrode 11 and the shield plate 12 are connected to a power source, and a voltage is appropriately applied.

  The discharge electrode 11 is a sawtooth electrode plate and is arranged along the axial direction of the photosensitive drum 10. The control electrode 13 is a grid electrode for controlling the charging potential of the photosensitive drum 10 to a predetermined potential, and is disposed between the photosensitive drum 10 and the discharge electrode 13. The shield plate 14 is a pair of conductive members (for example, stainless steel) facing each other with the discharge electrode 11 interposed therebetween, and is connected to a power source. Further, the shield member 14 and the control electrode 13 are integrally formed in a U-shaped cross section, and cover the discharge electrode 11 from three sides except the surface away from the photosensitive drum 10.

  The housing member 16 is a U-shaped insulating member (for example, a thermoplastic resin such as ABS) that is open on one side, and accommodates the shield plate 14 and the like. The housing member 16 is disposed so that the opening thereof faces the photosensitive drum 10.

  When the charging device 100 is opposed to the photosensitive drum 10, a predetermined interval is provided between the photosensitive drum 10 and the housing member 16. Therefore, it is necessary to prevent air leakage from this gap. Therefore, seal members 12 for closing the gaps are provided on the four sides surrounding the control electrode 13 of the housing member 16. The seal member 12 is held in a state where one side is fixed to the housing member 16 and the other side is in contact with the photosensitive drum 10.

  In the charging device 100, a predetermined interval is provided between the housing member 16 and the shield plate 14 by the housing member 16 that covers the shield plate 14. The member in which the shield member 14 and the control electrode 13 are integrated has a U-shaped cross section, and the surface away from the photosensitive drum 10 is open. Further, a gap with the photosensitive drum 10 is closed by a seal member 12 attached to the housing member 16. As a result, a circulation path is formed in which the ion flow generated by the discharge of the discharge electrode 11 to the photosensitive drum 10 circulates (see the broken line arrow in FIG. 2).

  Furthermore, an ozone removing member 15 for removing ozone is disposed between the housing member 16 and the shield plate 14. As the ozone removing member 15, for example, there is a member in which a material for removing ozone is applied or plated on a corrugated insulating plate. As a material for removing ozone, for example, activated carbon, manganese dioxide, lead peroxide, palladium, platinum, nickel, rhodium and the like are applicable.

  Next, the operation of the charging device 100 of this embodiment will be described. In the charging device 100, a voltage is applied to the discharge electrode 11 and the shield plate 14 and a grid voltage is applied to the control electrode 13 during an image forming operation. As a result, a discharge is generated from the discharge electrode 11, and the surface of the photosensitive drum 10 is uniformly charged to a predetermined potential.

  Further, during discharge, an ion flow from the vicinity of the discharge electrode 11 toward the photosensitive drum 10 is generated. The ion flow collides with the photosensitive drum 10 and is dispersed. The dispersed ion stream propagates along the seal member 12 and the housing member 16. Then, it propagates through the gap between the housing member 16 and the shield plate 14 and collides with the bottom surface of the housing member 16 to be dispersed again. The dispersed ion flow propagates again toward the photosensitive drum 10 from between the open shield members 14 and 14. Thereby, the ion flow generated by the discharge circulates in the charging device 100 as shown in FIG.

  And since the ozone removal member 15 is arrange | positioned in the circulation path | route of this ion flow, when an ion flow passes the ozone removal member 15, ozone in an ion flow is decomposed | disassembled favorably. Therefore, the ozone concentration in the charging device 100 is low.

  That is, the charging device 100 according to the first embodiment can circulate the ion flow generated by the discharge in the charging device 100 by providing the housing member 26 that accommodates the stabilizing plate 14. By disposing the ozone removing member 15 in the circulation path, ozone can be removed in the charging device 100. That is, in the charging device 100, ozone can be removed without providing a duct or a fan as in the conventional charging device. Therefore, the device itself is compact and inexpensive.

[Second form]
As shown in FIG. 4, the charging device 200 of the second embodiment has a discharge electrode 21, a seal member 22, a control electrode 23, a shield plate 24, an ozone removing member 25, and a housing member 26 that accommodates them. Yes. These arrangements are the same as those of the charging device 100 of the first embodiment. Therefore, as in the first embodiment, the charging device 200 is provided with a circulation path for the ion flow, and in the circulation path, specifically, the ozone removing member 25 is provided in the gap between the shield plate 24 and the housing member 26. Has been placed.

  A plurality of grooves 241 are provided on the outer wall of the shield plate 24. Furthermore, a plurality of grooves 261 are also provided on the inner wall of the housing member. This point is different from the first embodiment in which each wall surface is flat. Further, the ozone removing member 25 located between the shield plate 24 and the housing member 26 is also formed into a corrugated cross section in accordance with the shape of both wall surfaces. Therefore, the ion flow passes through the gap between the shield plate 24 and the housing member 26 while meandering.

  In the charging device 200 of the second embodiment, the ion flow passes around the ozone removing member 25 while meandering. Therefore, the contact area between the ion flow and the ozone removing member 25 is larger than that in the first embodiment. Therefore, ozone can be more efficiently removed.

  In addition, the ozone removal member 25 should just be the shape which meanders an ion flow, and is not restricted to a cross-sectional wave shape. Moreover, it is not limited to a single plate and may be composed of a plurality of plates.

[Third embodiment]
As shown in FIG. 5, the charging device 300 according to the third embodiment includes a discharge electrode 31, a seal member 32, a control electrode 33, a shield plate 34, an ozone removing member 35, and a housing member 36 for housing them. Yes. These arrangements are the same as those of the charging device 100 of the first embodiment. Therefore, as in the first embodiment, the charging device 300 is provided with a circulation path for the ion flow, and in the circulation path, specifically, the ozone removing member 35 is provided in the gap between the shield plate 34 and the housing member 36. Has been placed.

  The ozone removing member 35 is also disposed in the gap between the photosensitive drum 30 and the housing member 36, and its cross section has a stepped shape. That is, the ozone removing member 35 is also disposed inside the seal member 32. In this respect, the ozone removing member is not adjacent to the seal member and is different from the first embodiment in which the cross section is flat. As an example of the ozone removing member 35 having a stepped cross section, there is a stack of ozone removing members having different heights as shown in FIG.

  In the charging device 300 of the third embodiment, the ozone removing member 35 is disposed also in the gap between the photosensitive drum 30 and the housing member 36, and the ozone removing member 35 has a stepped cross section. Therefore, the contact area between the ion flow and the ozone removing member 35 is large. Therefore, ozone can be more efficiently removed.

[Fourth form]
As shown in FIG. 7, the charging device 400 of the fourth embodiment has a discharge electrode 41, a seal member 42, a control electrode 43, a shield plate 44, an ozone removing member 45, and a housing member 46 for housing them. Yes. These arrangements are the same as those of the charging device 100 of the first embodiment. Therefore, as in the first embodiment, the charging device 400 is provided with a circulation path for the ion flow. Specifically, the ozone removing member 45 is provided in the clearance between the shield plate 44 and the housing member 46 in the circulation path. Has been placed.

  The ozone removing member 45 has a four-layer structure in which four types of ozone removing members are stacked. This is different from the first embodiment having a single-layer structure. 8 to 11 show examples of the ozone removing member 45 having a four-layer structure. 8 and 9 show the ozone removing members 451 (first stage), 452 (second stage), 453 (third stage), and 454 (fourth stage) before being combined. 10 and 11 show the ozone removing member 45 after being combined. As shown in the drawings, the ozone removing members 451, 452, 453, and 454 constituting the ozone removing member 45 have different patterns.

  In the charging device 400 of the fourth embodiment, the ozone removing member 45 has a multilayer structure in which ozone removing members having different patterns are combined. Therefore, the contact area between the ion flow and the ozone removing member 45 is larger than that in the first embodiment. Therefore, ozone can be more efficiently removed.

  Note that the ozone removing member 45 of this embodiment may have a multilayer structure, and the number of layers is not limited to four. Moreover, the pattern of each layer which comprises a multilayer is not restricted to the illustrated pattern.

  As described above in detail, in the charging device of this embodiment, the discharge electrode is sandwiched between the shield plates, the shield plate is surrounded by the housing member, and the seal member closes the gap with the photosensitive drum. Thus, a circulation path for the ion flow is formed in the charging device. An ozone removing member is arranged in the circulation path. As a result, the ion stream circulates and ozone in the ion stream is appropriately removed. In this charging device, the ozone concentration can be reduced without providing a duct or a fan. Therefore, the device itself is compact and inexpensive. Therefore, a charging device that suppresses image noise due to ion flow is realized with a compact configuration.

  Note that this embodiment is merely an example, and does not limit the present invention. Therefore, the present invention can naturally be improved and modified in various ways without departing from the gist thereof. For example, the charging device of the present embodiment is for charging the photosensitive drum uniformly, but is not limited thereto. That is, any discharge device such as a transfer charger, a separation charger, or a static elimination charger can be applied. Further, the discharge electrode is not limited to the sawtooth discharge electrode plate, and may be, for example, a wire electrode or a pin electrode.

  In addition, the ozone removing member of the present embodiment is one in which activated carbon or the like is applied to a pre-molded resin plate, but is not limited thereto. For example, powdered activated carbon may be kneaded and molded. Further, the outer shape of the ozone removing member is not limited to a wave shape, and may be any shape that does not hinder the propagation of the ion flow. Further, the ozone removing member is not limited to a plate shape, and may be a net shape, for example.

  In addition, it is preferable that the seal member is completely in contact with the photosensitive drum from the viewpoint of preventing the outflow of the ion flow. May be. Further, it is preferable from the viewpoint of preventing the outflow of the ion flow that the housing member completely surrounds the shield plate, but it is sufficient that the ion flow is surrounded to the extent that the ion flow is generally circulated even if a part is opened.

  Further, the image carrier is not limited to the photosensitive drum, and may be, for example, an intermediate transfer member (belt, drum, roller, etc.) or a paper transport member (belt, etc.). Further, as the image forming apparatus using the charging device of the present embodiment, a copying machine, a printer, a FAX, a complex machine of these, or the like may be used.

It is a schematic explanatory drawing (perspective view) which shows the whole charging device concerning a 1st form. It is a schematic explanatory drawing (sectional drawing) which shows the whole charging device concerning a 1st form. It is a figure which shows the state before combining a charging device. It is a schematic explanatory drawing which shows the whole charging device concerning a 2nd form. It is a schematic explanatory drawing which shows the whole charging device concerning a 3rd form. It is a perspective view which shows the example of the ozone removal member where a cross section is step shape. It is a schematic explanatory drawing which shows the whole charging device concerning a 4th form. It is a perspective view (before combination) which shows the example of the ozone removal member of a 4 layer structure. It is a top view (before combination) showing an example of a four-layer structure ozone removing member. It is a perspective view (after combination) which shows the example of the ozone removal member of a 4 layer structure. It is a top view (after combination) showing an example of a 4-layer structure ozone removing member.

Explanation of symbols

10 Photosensitive drum (image carrier)
11 Discharge electrode
12 Sealing member
13 Control electrode 14 Shield plate (stabilizing plate)
15 Ozone removal member (ozone removal member)
16 Housing member (housing member)
100 Charging device (charging device)

Claims (6)

In a charging device for charging an image carrier by corona discharge,
A discharge electrode;
A pair of stabilizers facing each other across the discharge electrode;
A housing member that houses the stabilizer and has an opening on a surface facing the image carrier;
A seal member attached to the housing member and sealing a gap between the image carrier and the housing material;
A charging device comprising an ozone removing member that is located in a gap between the housing member and the stabilizer and removes ozone. The charging device according to claim 1,
The charging device according to claim 1, wherein the housing member is made of an insulating material. In the charging device according to claim 1 or 2,
The charging device, wherein the discharge electrode is a sawtooth electrode. In the charging device according to any one of claims 1 to 3,
The charging device according to claim 1, wherein an outer wall of the stabilizing plate and an inner wall of the housing member have a plurality of grooves. In the charging device according to any one of claims 1 to 4,
The ozone removing member is a stepped member, and the stepped portion is provided on the upstream side in the ion flow propagation direction. In the charging device according to any one of claims 1 to 5,
3. The charging device according to claim 1, wherein the ozone removing member has a structure in which molding members having different shapes with respect to the propagation direction of the ion flow are superposed.

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