JP5114134B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus such as a printer, a copier, and a facsimile transceiver using an electrophotographic system.

  As a prior art relating to this type of image forming apparatus, there is known one provided with a cleaning member such as a cleaning blade in order to collect untransferred toner remaining on the surface of the photoreceptor (see, for example, Patent Document 1). ). The cleaning blade scrapes off the remaining toner by coming into contact with the surface of the photoreceptor and collects it as untransferred toner. The recovered untransferred toner is received by the housing of the cleaning unit and is conveyed to the toner bottle by, for example, a toner recovery screw.

  Further, the image forming apparatus of the prior art (Patent Document 1) employs an amorphous silicon drum as a photoreceptor of an electrophotographic system. In this case, a cleaning roller is installed in the cleaning unit for the purpose of polishing the surface of the amorphous silicon drum. In this case, an abrasive such as titanium oxide has been transferred to the toner, and the polishing ability of the cleaning roller is satisfactorily exhibited by forming a toner layer on the surface thereof. At this time, if the toner layer is in a non-uniform state, uneven polishing may occur, and unevenness may occur in a half image or the like. Therefore, a toner layer regulating member (corresponding to “scraper” in Patent Document 1) is applied to the cleaning roller. The toner layer is made uniform by contact.

  Conventionally, in order to prevent the untransferred toner collected by the cleaning unit from spilling from the cleaning unit, a seal member is attached to the housing of the cleaning unit. The seal member is installed so as to close a space between the opening portion of the housing and the photosensitive member. In the prior art system, a sealing member is attached for the purpose of sealing between the opening portion of the housing for housing the cleaning roller and the toner collecting screw and the surface of the photoreceptor.

Since such a seal member has a certain degree of flexibility, if it is directly attached to a resin-molded housing, the seal member may often bend due to the warping of the housing after molding. is there. When the seal member is deflected, a gap may be generated in the attachment portion of the seal member, thereby causing a problem that untransferred toner is spilled from the gap. As a countermeasure, a method of attaching a seal member to a sheet metal member having a certain degree of rigidity and fixing the sheet metal member to the housing is often used. This method is intended to suppress (or absorb) the warping of the housing by the rigidity of the sheet metal member.
Japanese Patent Laid-Open No. 11-2996 (FIGS. 1 and 2)

  However, even if a sheet metal member is used for attaching the seal member, if the warpage of the housing is increased to some extent, the sheet metal member is also deformed thereby, and the seal member is bent as a result.

  In particular, in a system equipped with a cleaning roller as in the prior art, it is necessary to secure a space for bringing the cleaning roller into contact with the surface of the photosensitive member. Therefore, the seal member cannot be extended to this space. Therefore, the prior art system has a limitation that the seal member cannot be sufficiently brought into contact with the photosensitive member. Under such restrictions, the deformation of the seal member tends to cause a gap between the surface of the photosensitive member, and therefore it is necessary to suppress the warping during molding of the housing to a certain level. It takes a lot of time and effort to determine the conditions (design conditions, etc.).

  In addition, when a gap is generated between the sheet metal member and the housing, it is necessary to fill the gap with a sponge or the like in order to suppress toner spillage from the gap. In this case, a sponge for filling the gap is required as a separate part, and the number of steps for attaching the sponge is added to the manufacturing cost.

  On the other hand, in a system equipped with a cleaning roller as in the prior art, a sheet-like member such as PET is used as the toner layer regulating member. For example, this sheet-like member is a sponge (see FIG. Corresponding to the “member”.) In many cases, it is supported in the housing in a state where it is stuck on. In this case, if a shearing force acts on the sponge due to the rotation of the cleaning roller during long-term use, the sponge gradually deforms, and the pressing force for pressing the sheet-like member against the cleaning roller can be exerted. It may disappear.

  As described above, the structure of the conventional cleaning unit has a problem that the influence (seal failure) due to the warp of the housing cannot be sufficiently suppressed, and an extra cost is required to prevent toner spillage. In addition, in the case of a system using a cleaning roller as in the prior art, in addition to the problem of poor sealing, the pressing force of the toner layer regulating member cannot be maintained for a long period of time, and the cleaning performance (polishing ability) deteriorates. There is also the problem of doing.

  Therefore, the present invention aims to improve the sealing performance by eliminating the influence of the warp of the housing, and to achieve a cleaning unit structure excellent in applicability to an electrophotographic system using a cleaning roller. .

  The present invention relates to a photosensitive member on which an electrostatic latent image is formed, a developing device for developing the electrostatic latent image on the photosensitive member with toner to form a toner image, and the toner image transferred from the photosensitive member to a sheet. And a cleaning unit for purifying the surface of the photoreceptor after being formed.

  In particular, the cleaning unit in the image forming apparatus of the present invention basically has a structure in which a seal member is attached to a housing via a sheet metal member, and further supports the sheet metal member only at both ends viewed in the longitudinal direction of the housing. The above-mentioned problem is solved by making the sheet metal member non-contact with the outer surface of the housing in the central portion viewed in the longitudinal direction between both ends.

That is, the cleaning unit has a cleaning member that is provided at a position in contact with the surface of the photoconductor and collects untransferred toner from the surface of the photoconductor, and the housing houses the cleaning member therein. The untransferred toner collected from the surface of the photoreceptor is received. The seal member is attached to the outer surface of the housing via a sheet metal member, and this seal member seals between the inside of the housing and the surface of the photoreceptor. Further, sheet metal support portions are formed at both ends as viewed in the longitudinal direction of the housing, and these sheet metal support portions support the sheet metal member at two locations on both ends of the housing, and at least between these both ends. In the central portion as viewed in the longitudinal direction, the sheet metal member is structured so as not to contact the outer surface of the housing. The sheet metal member has an L-shaped cross section as viewed in the longitudinal direction of the housing, and a portion that is horizontal with respect to the outer surface of the housing is supported only by the sheet metal support portion, and a portion that is perpendicular to the horizontal portion. Supports the seal member, and a gap is formed between the vertical portion and the outer surface of the housing.

  In the structure of the present invention, the warp generated in the housing does not act greatly on the sheet metal member. In general, a resin-molded housing often warps with its entire longitudinal direction being curved, but the sheet metal member is contacted and supported only at both ends of the housing, and the two are not in contact with each other. A space for “escape” is secured in the center. In the structure of the present invention, the warp of the housing is allowed to escape into this space, thereby suppressing the influence of the warp of the housing on the sheet metal member.

  In the present invention, the photoreceptor for forming the toner image can be composed of an amorphous silicon drum. In this case, the toner for developing the electrostatic latent image is externally added with an abrasive that polishes the surface of the amorphous silicon drum, and the inside of the housing rotates with the untransferred toner attached to the peripheral surface. The cleaning roller for polishing the surface of the amorphous silicon drum, the toner layer regulating member for regulating the layer thickness of the untransferred toner adhering to the surface of the cleaning roller, and the state where the toner layer regulating member is pressed against the surface of the cleaning roller And an elastic member that contacts the inner surface of the sheet metal member so as to seal between the interior of the housing and the sheet metal member.

  If it is said structure, in order to fill the clearance gap between a housing and a sheet-metal member, another member is not required, but this can be combined with the elastic member which supports a toner layer control member. Further, even when a shearing force acts on the elastic member by the rotation of the cleaning roller, the shearing force can be received at the contact surface with the sheet metal member. As a result, deformation of the elastic member can be suppressed over a long period of time, and the toner layer regulating member can be supported in a state of being pressed well against the cleaning roller until the product lifetime.

  According to the present invention, even if a certain amount of warpage occurs in the housing, it is possible to suppress the deflection of the seal member and to maintain good sealing performance. In addition, the present invention is excellent in applicability to a system for polishing a photoreceptor using a cleaning roller, and can greatly contribute to improvement in durability while suppressing the manufacturing cost.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram schematically illustrating a configuration example of an image forming unit in an image forming apparatus according to an embodiment. Examples of the image forming apparatus of the present embodiment include a printer, a copying machine, a facsimile transceiver, a network type printer, a multifunction peripheral device (MFP), and the like. There are no restrictions on the format.

  The image forming unit shown in FIG. 1 includes, for example, a charging roller 12, a laser scanning unit (not shown), a developing roller 14, a transfer roller 16, and a cleaning unit 18 arranged around the photosensitive drum 10 as a center. Yes.

  For example, an amorphous silicon photosensitive layer is formed on the surface of the photosensitive drum 10. As the photosensitive drum 10 rotates, the photosensitive layer on the surface is charged by the charging roller 12. Thereafter, the charged photosensitive layer is exposed by the scanning light L from the laser scanning unit to form an electrostatic latent image. When this electrostatic latent image is then developed with toner carried around the developing roller 14, a toner image is formed on the surface of the photosensitive drum 10.

  During this time, the paper P conveyed by a paper feeding unit (not shown) is held by a registration roller (not shown) and stands by, for example. The registration roller sends out the paper P while synchronizing with the toner image formed on the surface thereof as the photosensitive drum 10 rotates. The fed paper P is conveyed between the photosensitive drum 10 and the transfer roller 16, and a toner image is transferred to the transfer surface of the paper P in this process. Thereafter, the paper P is heated and pressurized by a fixing unit (not shown), whereby the toner image is fixed on the paper P. The paper P that has passed through the fixing unit is discharged to a paper discharge tray (not shown) or conveyed to a double-sided tray, and this time, a toner image is transferred to the opposite surface.

  Next, the cleaning unit 18 in this embodiment will be described. The cleaning unit 18 includes a cleaning blade 20, and the cleaning blade 20 is provided at a position where it contacts (contacts) the surface of the photosensitive drum 10. The cleaning blade 20 scrapes off the untransferred toner remaining on the surface of the photosensitive drum 10 at a position upstream of the charging roller 12 and cleans the surface.

  Further, the cleaning unit 18 includes a cleaning roller 22, and the cleaning roller 22 is provided at a position that rotates following the rotation of the photosensitive drum 10, for example. The cleaning roller 22 polishes the surface of the photosensitive drum 10 with the untransferred toner layer adhered to the outer surface thereof, and prevents moisture from adhering to the surface. More specifically, for example, titanium oxide is externally added as an abrasive to the toner used in this embodiment, and surface polishing is performed with this abrasive. For the cleaning roller 22, a material such as EPDM or urethane rubber is used.

  The cleaning unit 18 includes a cleaning housing 24 as an outer shell. The cleaning housing 24 accommodates various components such as the cleaning blade 20 and the cleaning roller 22 therein. The cleaning housing 24 also functions as a container that receives untransferred toner scraped off by the cleaning blade 20 and temporarily retains the untransferred toner that adheres to the cleaning roller 22. For example, a toner collection screw 26 is installed in the cleaning housing 24, and untransferred toner collected in the cleaning housing 24 is conveyed to a toner bottle (not shown) as the toner collection screw 26 rotates.

  In addition, a toner layer regulating member 32 is attached to the inside of the cleaning housing 24 via, for example, a sponge (elastic member) 34, and the toner layer regulating member 32 contacts (contacts) the outer surface of the cleaning roller 22. ing. For example, a material such as urethane foam is used for the sponge 34, and the sponge 34 presses the toner layer regulating member 32 against the cleaning roller 22 with an appropriate pressing force by an elastic force. The toner layer regulating member 32 makes the layer thickness of the toner formed on the outer surface of the cleaning roller 22 uniform. By making the toner layer uniform in this way, the polishing ability by the cleaning roller 22 is made uniform in the longitudinal direction, and the image forming state by the photosensitive drum 10 can be maintained well.

  A cleaning seal 30 is attached to the outer surface of the cleaning housing 24 via a sheet metal member 28. The cleaning seal 30 is, for example, a flexible plate-like member, and is supported in a state where the base end portion is attached to the sheet metal member 28. Further, the cleaning seal 30 extends upward from the sheet metal member 28, and a tip portion thereof is brought into contact (contact) with the surface of the photosensitive drum 10. The cleaning seal 30 seals between the opening of the cleaning housing 24 and the surface of the photosensitive drum 10 to prevent toner spillage from the cleaning housing 24.

  Here, the sheet metal member 28 has an L-shaped cross section in the longitudinal direction. Further, the sheet metal member 28 supports the cleaning seal 30 at a vertical portion of the L-shaped cross section. However, in this state, the vertical portion of the L-shaped cross section of the sheet metal member 28 is not in direct contact with the outer surface of the cleaning housing 24, and a gap is secured between the inner surface of the sheet metal member 28 and the outer surface of the cleaning housing 24. Has been. On the other hand, the horizontal portion of the L-shaped cross section of the sheet metal member 28 is attached to the lower surface of the cleaning housing 24. Hereinafter, attachment of the sheet metal member 28 to the cleaning housing 24 will be described.

  FIG. 2 is a detailed view of the cleaning unit 18 including a cross section taken along line II-II in FIG. A cross section inside the cleaning unit 18 is shown on the right side of the alternate long and short dash line shown in FIG. 2, and the outer surfaces of the cleaning seal 30 and the sheet metal member 28 are shown on the left side of the alternate long and short dash line. Yes.

  The cleaning housing 24 is formed with sheet metal support portions 24a at both ends as viewed in the longitudinal direction. These sheet metal support portions 24a protrude one step downward from the lower surface of the cleaning housing 24, and the lower surface of the sheet metal member 28 is fixed, that is, supported as described above. On the other hand, between the two sheet metal support portions 24a, the sheet metal member 28 and the outer surface of the cleaning housing 24 are not in contact with each other, and a space portion 24b is secured at the center in the longitudinal direction.

  Thereby, for example, even if a vertical warp (or a horizontal warp indicated by an arrow H) indicated by an arrow V in FIG. 2 occurs in the cleaning housing 24, the space portion 24b becomes “escape”, The sheet metal member 28 is not deformed by the influence of the warp. Further, as described above, the vertical portion of the L-shaped cross section of the sheet metal member 28 is not in direct contact with the outer surface of the cleaning housing 24, and a gap is secured. For this reason, even if a warp in the horizontal direction (arrow H) occurs in the cleaning housing 24 in particular, the gap also becomes “escape” and the sheet metal member 28 is not deformed by the influence of the warp. For this reason, in this embodiment, it is possible to effectively prevent the cleaning seal 30 from being bent, and it is possible to maintain the sealing performance of the cleaning seal 30 well and prevent toner spillage.

  On the other hand, in this state, toner spillage due to the deflection of the cleaning seal 30 can be avoided, but the toner may fall through a gap between the cleaning seal 30 or the inner surface of the sheet metal member 28 and the cleaning housing 24. Therefore, in the present embodiment, the sponge 34 is extended along the bottom surface inside the cleaning housing 24, and one end surface of the sponge 34 is brought into contact with the inner surface of the sheet metal member 28. Accordingly, it is possible to effectively suppress toner spillage by combining with the sponge 34 without newly installing a sponge for preventing toner spillage as a separate part.

  Further, in the present embodiment, the one-side end surface of the sponge 34 is brought into contact with the inner surface of the sheet metal member 28 at the same time, so that the deformation of the sponge 34 over time due to the rotation of the cleaning roller 22 can be suppressed. That is, when the cleaning roller 22 is rotated following the rotation of the photosensitive drum 10, a shearing force is applied to the sponge 34, but one end surface of the sponge 34 is in contact with the inner surface of the sheet metal member 28. The reaction force here can cancel the shearing force and prevent the entire sponge 34 from being deformed. Thereby, the pressing force of the toner layer regulating member 32 by the sponge 34 can be maintained throughout the product life.

  The present invention can be implemented with various modifications without being limited to the above-described embodiment. In the embodiment, the photosensitive drum 10 is an amorphous silicon drum and the cleaning roller 22 is installed in the cleaning unit 18. However, the photosensitive drum 10 may not be an amorphous silicon drum. In this case, the cleaning roller 22 only needs to assist the purification action by the cleaning blade 20 like a brush roller, so that it is not necessary to install the toner layer regulating member 32 in particular.

FIG. 2 is a diagram schematically illustrating a configuration example of an image forming unit in an image forming apparatus according to an embodiment. It is detail drawing of the cleaning unit containing the cross section which follows the II-II line in FIG.

Explanation of symbols

10 Photosensitive drum 12 Charging roller 14 Developing roller (developer)
DESCRIPTION OF SYMBOLS 16 Transfer roller 18 Cleaning unit 20 Cleaning blade 22 Cleaning roller 24 Cleaning housing 24a Sheet metal support part 24b Space part 28 Sheet metal member 30 Cleaning seal 32 Toner layer regulation member 34 Sponge

Claims (2)

A photosensitive member on which an electrostatic latent image is formed, a developing unit for developing the electrostatic latent image on the photosensitive member with toner to form a toner image, and after the toner image is transferred from the photosensitive member to paper In an image forming apparatus comprising a cleaning unit for purifying the surface of the photoconductor
The cleaning unit includes
A cleaning member provided at a position in contact with the surface of the photoreceptor, and collecting untransferred toner from the surface of the photoreceptor;
A housing that houses the cleaning member therein and receives untransferred toner collected from the surface of the photoreceptor;
A seal member attached to the outer surface of the housing via a sheet metal member, and sealing between the interior of the housing and the surface of the photoreceptor;
The sheet metal member is formed at both end portions as viewed in the longitudinal direction of the housing, and supports the sheet metal member at two positions of the both end portions, and at least the central portion viewed in the longitudinal direction between the both end portions. have a sheet metal support section according to non-contact with the outer surface,
The sheet metal member is
A cross section of the housing in the longitudinal direction is L-shaped, and a portion horizontal to the outer surface of the housing is supported only by the sheet metal support, and a portion perpendicular to the horizontal portion is the sealing member supports a image forming apparatus characterized that you have a gap is formed between the vertical portion and the outer surface of the housing. The image forming apparatus according to claim 1.
The photoreceptor is composed of an amorphous silicon drum,
An abrasive for polishing the surface of the amorphous silicon drum is externally added to the toner,
Inside the housing,
A cleaning roller that polishes the surface of the amorphous silicon drum while rotating with untransferred toner attached to the peripheral surface;
A toner layer regulating member for regulating the layer thickness of untransferred toner adhering to the surface of the cleaning roller;
An elastic member that supports the toner layer regulating member in a pressed state against the surface of the cleaning roller, and that contacts the inner surface of the sheet metal member to seal between the interior of the housing and the sheet metal member; An image forming apparatus provided with the image forming apparatus.

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