Image forming apparatus capable of effectively performing a maintenance operation

A roller device that can be exchangeably used in an image forming apparatus includes a roller, a shaft, and two grip members. The roller is configured to cover the shaft along the rotation axis and have two roller ends from which the two shaft end portions of the shaft are projected outwardly along the rotation axis. A shaft is configured to have a rotation axis at a center thereof and have two shaft end portions. The two grip members are each configured to be rotatably disposed to a respective shaft end portion of the two shaft end portions.

CROSS REFERENCE TO RELATED APPLICATIONS

This patent specification is based on Japanese Patent Application No. JP2005-353955, filed on Dec. 7, 2005 in the Japan Patent Office, the entire contents of which are incorporated by reference herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus capable of effectively performing a maintenance operation by increasing operability of a roller device.

2. Description of the Related Art

Conventionally, an image forming apparatus, such as a copier, a printer, a facsimile, or a multi-function device, which uses an electrophotographic method, generally employs a transfer roller as a mechanism to transfer a toner image formed on a surface of an image carrier onto a recording member. The transfer roller includes a metal core and a conductive elastic body layer. The conductive elastic body layer is made of conductive rubber, conductive sponge, etc., and is integrally formed in a roller shape around the metal core.

The transfer roller is rotatably supported on both ends thereof by shaft receiving members, and contacts, with pressure, the surface of the image carrier. When the recording member is passed through a nip portion between the transfer roller and the surface of the image carrier, the transfer roller is applied with a polarity opposite to a charged polarity of the toner image. Thus, the toner image is transferred onto a surface of the recording member.

In this regard, since the conductive elastic body layer of the transfer roller contacts, with pressure, the surface of the image carrier, the conductive elastic body layer of the transfer roller is worn out in continuous use. A surface of the conductive elastic body layer of the transfer roller is abraded due to a difference in linear velocity between the transfer roller and the image carrier. In addition, attachment of toner or paper dust may cause a change in a surface property of the conductive elastic body layer, thereby deteriorating transfer performance thereof and image quality.

For these reasons, the transfer roller is generally configured to be attachable to and detachable from an image forming apparatus so as to be quickly replaced with a replacement transfer roller when the transfer roller is degraded.

So far, a replacement operation of such a roller member in the image forming apparatus has been generally performed by technical support staff familiar with replacing transfer rollers. That is, general users have hardly performed the replacement operation. As a result, not much attention has been paid to operability of a replacement roller member in the replacement operation thereof.

However, general users are increasingly performing the replacement operation by themselves for some reasons, such as saving on maintenance costs of an image forming apparatus. Therefore, an increase in operability of the replacement roller member is desired so that general users may properly and effectively perform the replacement operation thereof.

SUMMARY OF THE INVENTION

This patent specification describes a roller device for use in an image forming apparatus in which a maintenance operation can be effectively performed by increasing operability of a replacement roller device. In one example, a roller device includes a roller, a shaft, and two grip members. The roller is configured to cover the shaft along the rotation axis and have two roller ends from which the two shaft end portions of the shaft are projected outwardly along the rotation axis. A shaft is configured to have a rotation axis at a center thereof and have two shaft end portions. The two grip members are configured to be rotatably disposed to a respective shaft end portion of the two shaft end portions.

This patent specification further describes a roller replacement package for use in an image forming apparatus in which a maintenance operation can be effectively performed by increasing operability of a replacement roller device. In one example, a roller replacement package includes a roller device, a housing member, and a supporter. The roller device includes a roller, a shaft, and two grip members. The roller is configured to cover the shaft along the rotation axis and have two roller ends from which the two shaft end portions of the shaft are projected outwardly along the rotation axis. The shaft is configured to have a rotation axis at a center thereof and have two shaft end portions. The two grip members are configured to be rotatably disposed to a respective shaft end portion of the two shaft end portions. The housing member is configured to house the roller device, wherein the housing member has an outlet through which the roller device is installed and removed, and the outlet is formed such that the roller device is installed and removed in a direction perpendicular to the rotation axis. The supporter is configured to support the roller device such that the two grip members of the roller device are positioned towards the outlet of the housing member.

This patent specification still further describes an image forming apparatus in which a maintenance operation can be effectively performed by increasing operability of a replacement roller device. In one example, an image forming apparatus includes a roller device, a bearing member, and a supporter. The roller device is configured to be exchangeably used in the image forming apparatus. The bearing member is configured to be attached to one of the two shaft end portions. The supporter is configured to support the shaft by holding the one of the two shaft end portions through the bearing. The roller device includes a roller, a shaft, and two grip members. The roller is configured to cover the shaft along the rotation axis and have two roller ends from which the two shaft end portions of the shaft are projected outwardly along the rotation axis. The shaft is configured to have a rotation axis at a center thereof and have two shaft end portions. The two grip members are configured to be rotatably disposed to a respective shaft end portion of the two shaft end portions.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In describing preferred embodiments illustrated in the drawings, specific terminology is employed for the sake of clarity. However, the disclosure of this patent specification is not intended to be limited to the specific terminology so selected and it is to be understood that each specific element includes all technical equivalents that operate in a similar manner. Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views, particularly toFIG. 1, an image forming apparatus200according to an example embodiment of the present invention is described.

As illustrated inFIG. 1, the image forming apparatus200includes an apparatus body50and a duplexing unit60.

The apparatus body50includes an intermediate transfer belt11, image forming units10m,10c,10y, and10k, an optical write device14, sheet feed trays15aand15b, sheet feed mechanisms16aand16b, a conveyance roller pair17, a registration roller pair18, a transfer opposing roller13, a transfer exit guide101, a fuser20, switching pawls21,22, and23, conveyance roller pairs24,25,26, and27, sheet sensors35,36,37,38,39,40, and41, a sheet output roller pair29, and a sheet output tray30.

The duplexing unit60includes a switchback conveyance path61, a sheet re-feed path62, a first reversing roller pair31, a second reversing roller pair32, a manual feed tray33, a manual feed mechanism34, and a re-feed roller28. For the apparatus body50, the intermediate transfer belt11is provided in a substantially central portion thereof. The intermediate transfer belt11is looped over a plurality of rollers including the transfer opposing roller13and first transfer rollers12.

The image forming units10m,10c,10y, and10kare disposed along a downward outer surface of the intermediate transfer belt11with respect to a vertical direction. Each of the image forming units10m,10c,10y, and10khas a photoconductor1, a charger, a developer, and a cleaner. Each of the photoconductors1serves as an image carrying member, and is surrounded by the charger, the developer, and the cleaner.

Each of the first transfer rollers12is disposed along an inner circumferential surface of the intermediate transfer belt11so as to face the corresponding photoconductor1. Each of the first transfer rollers12serves as a first transfer mechanism to transfer a toner image formed on the photoconductor onto the downward outer surface of the intermediate transfer belt11.

According to the present example embodiment, the image forming units10m,10c,10y, and10khave a similar configuration except for colors handled in the developers. That is, the developers in the image forming units10m,10c,10y, and10khandle developing agents of magenta, cyan, yellow, and black colors, respectively.

Furthermore, in the present example embodiment, the image forming mechanisms10m,10c,10y, and10kare disposed in a color order of magenta, cyan, yellow, and black with respect to a traveling direction of the intermediate transfer belt11, which indicated by an arrow A inFIG. 1. Each of the image forming units10m,10c,10y, and10kis configured as a replaceable cartridge, and is attachable to and is detachable from the apparatus body50.

The optical write unit14is disposed under the image forming units10m,10c,10y, and10k. The optical write unit14includes a polygon mirror (not illustrated) and a group of mirrors (not illustrated). The optical write unit14emits a modulated laser beam onto a surface of the photoconductor1in each of the image forming units10m,10c,10y, and10k. The optical write unit14may be separately provided for each of the image forming units10r,10c,10y, and10k.

Incidentally, according to the present example embodiment, each of the intermediate transfer belt11and the optical write unit14is configured as a single unit, and is attachable to and detachable from the apparatus body50.

The sheet feed trays15aand15bare disposed in two stages in a lower portion of the apparatus body50. The sheet feed trays15aand15bstore a recording member (hereinafter, referred to as a “sheet”) such as a transfer sheet. The sheet feed trays15aand15bare also provided with the corresponding sheet feed mechanisms16aand16b, respectively.

Each of the sheet feed mechanisms16aand16bincludes a pick-up roller, a supply roller, and a separation roller. The conveyance roller pairs17are provided so as to convey a sheet, which is fed with any one of the sheet feed mechanisms16aand16b.

The registration roller pair18is disposed above the conveyance roller pairs17. That is, the registration roller pair18is disposed on a downstream side of the conveyance roller pairs17in a conveyance direction of the sheet.

The secondary transfer roller100is a roller member that serves as a secondary transfer mechanism. Specifically, the secondary transfer roller100transfers the toner image transferred on the intermediate belt11onto the sheet that has been conveyed from any one of the sheet feed trays16aand16b. The secondary transfer roller100is disposed above the registration roller pair18so as to face the transfer opposing roller13. The transfer opposing roller13is looped with the intermediate transfer belt11.

The transfer exit guide101is disposed at an adjacent position above the secondary transfer mechanism. The transfer exit guide101serves as a conveyance regulation member to regulate a conveyance direction of the sheet by contacting the sheet in conveyance. The fuser20is disposed on a downstream side of the transfer exit guide101in the sheet conveyance direction.

The switching pawls21,22, and23are disposed above the fuser20so as to switch directions in which the sheet is conveyed. Each of the switching pawls21,22, and23changes a position thereof from a position indicated by a full line inFIG. 2to a position indicated by a-corresponding broken line. At this time, the position of each of the switching pawls21,22, and23is switched with an unillustrated actuator such as a solenoid.

Each of the conveyance rollers24to27is disposed in an appropriate position along sheet conveyance paths. Furthermore, each of the sheet sensors35to41is also disposed in an appropriate position along the sheet conveyance paths. Incidentally, a sheet is guided to an appropriate sheet conveyance path with guide members (not numbered) such as a guide plate.

The upper surface of the apparatus body50is configured to serve as the sheet output tray30. The sheet output roller pair29is disposed diagonally upward left from the fuser20inFIG. 1. The sheet output roller pair29outputs a sheet to the sheet output tray30.

According to the present example embodiment, the duplexing unit60is disposed at a side surface of the image forming apparatus200. The duplexing unit60includes the switchback conveyance path61and the sheet re-feed path62.

The first reversing roller pair31is disposed at an entrance portion of the switchback conveyance path61. The entrance portion of the switchback conveyance path61is located in an upper portion of the image forming apparatus200. Further, the second reversing roller pair32is disposed along the switchback conveyance path61. The first reversing roller pair31and the second reversing roller pair32are configured to be rotatable in both clockwise and counterclockwise directions.

In addition, the conveyance roller pairs26and27are disposed at positions so as to substantially equally divide the sheet re-feed path62into three pieces. The switching pawl23is disposed at an adjacent position of the first reversing roller pair31so as to be located at an entrance portion from the switchback conveyance path61to the sheet re-feed path62.

The manual feed tray33is configured to be housed into and ejected from a portion of an outer side surface of the duplexing unit60.FIG. 1illustrates a state where the manual feed tray33is ejected.

The manual feed mechanism34is provided to feed a sheet from the manual feed tray33to a sheet conveyance path. The manual feed mechanism34includes a pick-up roller, a supply roller, and a separation roller.

The re-feed roller28is disposed at a lateral side of the manual feed mechanism34, that is, at a closer position to the apparatus body50. Driven rollers are provided so as to contact with pressure an upper portion and an lower portion of the re-feed roller28, respectively.

The re-feed roller28is configured to be rotatable in both clockwise and counterclockwise directions. When a sheet is re-fed from the sheet re-feed path62, the re-feed roller28is rotated in the clockwise direction illustrated inFIG. 1. On the other hand, when a sheet is re-fed from the manual feed tray33, the re-feed roller28is rotated in the counterclockwise direction illustrated inFIG. 1.

Below, an image forming operation is described for the image forming apparatus200configured as above.

Upon starting the image forming operation, the photoconductor1in each of the image forming units10m,10c,10y, and10k, is rotationally driven in a clockwise direction inFIG. 1by an un-illustrated driving mechanism. A surface of the photoconductor1is uniformly charged with a given polarity by the charger.

The optical write unit14irradiates a laser beam onto the surface of the photoconductor1to form an electrostatic latent image thereon. At this time, original full-color image data is decomposed into single-color image data in magenta, cyan, yellow, and black. Then, the photoconductor1is exposed with the laser beam according to the decomposed single-color image data.

The electrostatic latent image formed on the surface of the photoconductor1is visualized with each color toner of magenta, cyan, yellow, and black in the developer.

The developer supplies each color toner of magenta, cyan, yellow, and black to the electrostatic latent image that has been formed on the surface of the photoconductor1. Thus, the electrostatic latent image is visualized as a toner image in each color.

In each of the image forming units10m,10c,10y, and10k, the toner image in each color is sequentially transferred onto the surface of the intermediate transfer belt11. At this time, the intermediate transfer belt11is rotationally driven in a counterclockwise direction as indicated by the arrow A inFIG. 1. Therefore, the toner images in magenta, cyan, yellow and black are sequentially superimposed on the surface of the intermediate transfer belt11. Thus, the intermediate transfer belt11carries a full-color toner image on the surface thereof.

Incidentally, the image forming apparatus200may form a single-color image by using any one of the image forming units10m,10c,10y, and10k. The image forming apparatus200may also form a color image by using any two or three of the image forming units10m,10c,10y, and10k. In monochrome image forming, the image forming apparatus200uses only the image forming unit10k.

After all of the toner images are transferred onto the intermediate transfer belt11, the cleaner in each of the image forming units10m,10c,10y, and10kremoves excess toner remaining on the surface of the photoconductor1. Then, the surface of the photoconductor1is discharged with an un-illustrated discharger so that a surface potential of the photoconductor1is initialized in preparation for a subsequent image forming operation.

Meanwhile, a sheet is selectively fed from any one of the sheet feed tray15a, the sheet feed tray15b, and the manual feed tray33. The sheet is sent out to the secondary transfer mechanism by the registration roller pair18so as to match a timing when the full-color toner image carried on the intermediate transfer belt11is conveyed to the secondary transfer mechanism.

According to the present example embodiment, the secondary transfer roller100is applied with a transfer voltage having an opposite polarity to a polarity with which the full-color toner image on the intermediate transfer belt11is charged. Thereby, the full-color toner image is collectively transferred onto the sheet.

While the sheet on which the full-color toner image has been transferred passes through the fuser20, the full-color toner image is fused and is fixed on the sheet. After the fusing process, the sheet is output to the sheet output tray30, which is disposed on the upper surface of the apparatus body50.

For a single-sided operation, a thick solid line B illustrated inFIG. 2indicates a sheet conveyance route from the sheet feed trays15aand15b.

An optional sheet output tray (not illustrated), such as a four-compartment sorting tray, may be configured to be attachable on the upper surface of the apparatus body50above the switching pawl22. Thus, after the fusing process, the sheet may be output to the optional sheet feed tray. For this case, a thick broken line C inFIG. 2indicates a sheet conveyance route after the sheet passes through the fuser20.

For a double-sided operation, a full-color toner image is transferred on one surface of a sheet, and then the sheet is sent out into the switchback conveyance path61by appropriately switching the positions of the switching pawls21,22, and23.

At this time, each position of the switching pawls21and22is changed from a position indicated by a thick solid line inFIG. 2to a position indicated by a thin broken line inFIG. 2. The position of the switching pawl23is changed from a position indicated by a thin broken line inFIG. 2to a position indicated by a thick solid line inFIG. 2. The reversing roller pairs31and32are rotated in an clockwise direction inFIG. 2.

When the sheet is sent out into the switchback conveyance path61, a sheet conveyance route after passing through the conveyance roller pair25is indicated by a chain double-dashed line D inFIG. 2.

When the sheet sensor40detects a trailing edge of the sheet that has been sent into the switchback conveyance path61, the reversing roller pairs31and32are reversely rotated in clockwise directions inFIG. 2, thereby reversing the sheet conveyance direction of the sheet. Then, the position of the switching pawl23is changed to the position indicated by a thin broken line inFIG. 2, and the sheet is sent out into the re-feed path62.

The re-feed path62merges with the sheet conveyance path from the manual sheet feed tray33at the lower end thereof. The re-feed path62also merges with the sheet conveyance path from the sheet feed trays15aand15bat an inner side of the re-feed roller28relative to the center of the apparatus body50. The sheet is conveyed through the re-feed path62with the conveyance roller pairs26and27, and is then conveyed to the registration roller pair18with the re-feed roller28.

For the case when the sheet is conveyed through the re-feed path62, a single-dashed line E inFIG. 2indicates a sheet conveyance route from the switching pawl23to the joint point with the thick solid line B. Further, for the case when a sheet is fed from the manual feed tray33, a dashed line F inFIG. 2indicates a sheet conveyance path from the manual feed tray33to a position immediately after passing through the re-feed roller28.

The sheet is reversed upside down by passing through the re-feed path62relative to the surface on which the intermediate transfer belt11carries a full-color toner image. Then, the full-color toner image is transferred from the intermediate transfer belt11onto the opposite surface of the sheet.

The transferred full-color image is fixed on the opposite surface of the sheet with the fuser, causing the sheet to carry the full-color toner images on both of the surfaces thereof. The resultant sheet is output to the sheet output tray30or the un-illustrated optional tray, and thus the dual-sided printing operation is finished.

According to the present example embodiment, the duplexing unit60is attached to the apparatus body50so as to be swayed by using a rotating shaft63as a pivot. Therefore, the duplexing unit60is openable and closable with respect to the apparatus body50.FIG. 3illustrates a state where the duplexing unit60is opened.

In addition, the duplexing unit60is supported by an un-illustrated link mechanism so as to be stopped at an appropriate position at opening. At this time, an open angle is preferably in a range of about 45 degrees to about 90 degrees, from a viewpoint of efficiency in a below-described replacement operation of the secondary transfer roller. The link mechanism, which supports the duplexing unit60, is preferably provided with a damper mechanism so that a required force may be reduced in opening and closing of the duplexing unit60. The damper mechanism may include a spring damper or an oil damper.

Further, as openable and closable members relative to the apparatus body50, the duplexing unit60includes guide plates (not numbered) forming the switchback conveyance path61, a guide member66forming a part of the re-feed path62, a supplementary rotation unit64, driven rollers17bof the conveyance roller pairs17, in addition to the switching pawl23, the reversing roller pairs31and32, the manual feed tray33, the manual feed mechanism34, and the re-feed roller28.

The supplementary rotation unit64is configured to be rotatable around a rotation shaft65serving as a fulcrum shaft. The supplementary rotation unit64supports the secondary transfer roller100, a driven roller27bof the conveyance roller pair27, a driven roller26bof the re-feed roller28, and the sheet sensor41(shown inFIG. 1).

Therefore, the re-feed path62is openable by rotating the supplementary rotation unit64in a counterclockwise direction G inFIG. 3. A rotation angle of the supplementary rotation unit64in the counterclockwise direction G is limited with an un-illustrated stopping member approximately up to an angle as illustrated inFIG. 3.

The re-feed path62is defined on one side (the right side inFIG. 3) thereof with the guide member66, and on the other side (the left side inFIG. 3) thereof with the guide member42, the fuser20, and the supplementary rotation unit64. When the duplexing unit60is closed to the apparatus body50, the re-feed path62is formed with the above members.

When the duplexing unit60is closed to the apparatus body50as illustratedFIG. 1, the supplementary rotation unit64is set to a given position by being sandwiched with the apparatus body50and the duplexing unit60. The secondary transfer roller100is contacted to the intermediate transfer belt11with pressure so as to face the transfer opposing roller13. The respective driven rollers17bof the conveyance roller pairs17are contacted to the corresponding drive rollers17awith pressure. The driven roller27bof the conveyance roller pair27is contacted to the drive roller27awith pressure. Thus, the duplexing unit60becomes operable.

On the other hand, when the duplexing unit60is opened from the apparatus body50, the secondary transfer roller100is separated from a portion of the intermediate transfer belt11which the transfer opposing roller13contacts with pressure. Further, the respective driven rollers17bof the conveyance roller pairs17are separated from the corresponding drive rollers17a. Thus, an ordinary sheet conveyance path43, which is indicated by a thick solid line inFIG. 3, is opened in an area from the lower conveyance roller pair17to the fuser20.

At this time, when the supplementary rotation unit64is rotated in a direction in which the re-feed path62is opened, that is, in the counterclockwise direction G inFIG. 3, the re-feed path62is opened from the switching pawl23to a merging point H, a point at which the re-feed path62merges with the ordinary sheet conveyance path43.

Next, a configuration of the secondary transfer roller100ofFIG. 1is described in more detail with reference toFIGS. 4 to 6.

FIG. 4is an appearance perspective diagram of the secondary transfer roller100that is attachable to and detachable from the supplementary rotation unit64(shown inFIG. 1). According to the present example embodiment, the secondary transfer roller100includes a roller portion102and two shaft end portions103thereof. The roller portion102may be an elastic body formed on an outer circumferential surface of a metal core. The shaft end portions103may be end portions of the metal core that are projected outward from ends of the roller portion102in a rotation axis direction-of the roller portion102.

Further, a roller attachment part104aof a gripper104may be rotatably attached to each of the shaft end portions103via an un-illustrated ball bearing member (refer to106inFIG. 9). The gripper104serves as a handgrip and is integrally formed with-the transfer exit guide101, which serves as a conveyance regulation member. The transfer exit guide101may also serve as a handgrip member.

According to the present example embodiment, the transfer exit guide101and the gripper104are integrally molded ABS (acrylonitrile butadiene styrene) resin. Materials of the transfer exit guide101and the gripper104are not limited to ABS resins, and may include PC (polycarbonate) resins and other resins.

However, members made of ABS resin generally have relatively high flexibility compared to members made of PC resin or AS (acrylonitrile styrene) resin. Thus, when the roller attachment part104aof the gripper104is attached to and detached from the end portions of the metal core forming the shaft end portion103in the secondary transfer roller100, the members made of ABS resin generally have relatively high resistance to damage and therefore are easier to handle compared to the members made of PC resins or AS resins.

On the other hand, from a viewpoint of sheet guide performance, the transfer exit guide101is preferably made of a resin that does not contain any butadiene component. One reason is that when the transfer exit guide101is made of a resin containing butadiene component, a charged amount of the transfer exit guide101resulting from friction with a sheet may be increased, thereby disturbing a toner image that is not still fixed on the sheet.

Incidentally, although the gripper104and the transfer exit guide101are integrally molded in the present example embodiment, the gripper104and the transfer exit guide101may be configured as separate members and then be fixed with each other.

The shaft end portions103of the secondary transfer roller100are also projected outward from the roller attachment parts104ain the rotation axis direction of the roller portion102.

Caps105serving as a cap-shaped shaft bearing member are attached to the projected portions of the shaft end portions103. The caps105are fixed by being sandwiched with un-illustrated sandwiching members serving as roller support members. The un-illustrated sandwiching members are provided in the intermediate transfer unit including the intermediate transfer belt11. Thus, a position of the secondary transfer roller100is fixed with respect to a vertical direction of the apparatus body50(shown inFIG. 1).

The caps105may be made of polyacetal resin or other resin having a relatively low friction coefficient with an outer circumferential surface of the shaft end portion103. Accordingly, even when the cap105is sandwiched with the sandwiching members, a relatively low friction is obtained between an inner circumferential surface of the cap105and the outer circumferential surface of the metal core of the shaft end portion103. Thus, the secondary transfer roller100becomes rotatable with relatively low load.

FIG. 5is an enlarged diagram illustrating an end portion of the secondary transfer roller100shown inFIG. 4. InFIG. 5, the end portion of the left side in the secondary transfer roller100ofFIG. 4is enlarged. The secondary transfer roller100is viewed from the side facing the supplementary rotation unit64(shown inFIG. 3) when the secondary transfer roller100is attached to the supplementary rotation unit64.

As illustrated inFIG. 5, the cap105includes a cap body105a, a marked member105b, and a connecting member105c. The cap body105ahas a cylindrical shape including an inner hollow into which the shaft end portion103is inserted. The marked member105bincludes an arrow I indicating a direction in which the secondary transfer roller100is attached to the supplementary rotation unit64. The connecting member105cis extended from an outer circumferential surface of the cap body105aoutward in a radial direction of the cap body105a. The marked member105bis connected to the cap body105awith the end portion of the connecting member105c.

According to the present example embodiment, as described below, while the transfer exit guide101is kept above the roller portion102with respect to a vertical direction of the apparatus body50, the secondary transfer roller100is moved vertically downward to the supplementary rotation unit64. Thus, the secondary transfer roller100is attached to the supplementary rotation unit64. As illustrated inFIG. 5, the arrow I indicating the attachment direction is formed on a plain surface of the marked member105b.

According to the present example embodiment, a fixing member is provided to fix the cap105into the roller attachment part104aof the gripper104and to suppress unintended detachment of the cap105from the shaft end portion103. The fixing member includes the connecting member105cthat serves as an engaging part of the cap105, and sandwiching members104bthat serve as an engaged part disposed at an outer side of each of the roller attachment parts104ain the rotation axis direction of the roller portion.

When the cap105is attached to the shaft end portion103from an outer side of the shaft end portion103in the rotation axis direction of the roller portion, the connecting member105cis sandwiched with the sandwiching members104bof the roller attachment part104a. Thus, the cap105is fixed to the roller attachment part104ain a so-called snap-fit manner.

For the secondary transfer roller100having the configuration as described above, when an operator, such as a user or technical service staff, performs a replacement operation of the secondary transfer roller100, the operator can grip the grippers104disposed at the ends of the secondary transfer roller100with both hands, or grip the transfer exit guide101with a single hand or both hands.

In the secondary transfer roller100, the gripper104and the transfer exit guide101are disposed at positions so as to be easily gripped by the operator, compared to the roller portion102and the shaft end portion103. Further, the gripper104and the transfer exit guide101are configured in shapes that can be easily gripped by the operator, compared to the roller portion102and the shaft end portion103.

Accordingly, the operator can handle the secondary transfer roller100by griping the gripper104or the transfer exit guide101in the replacement operation of the secondary transfer roller100. As a result, it is less likely that the operator handles the secondary transfer roller100by gripping the roller portion102or the shaft end portion103.

Thus, attachment of dirt from the operator's hand to a surface of the roller portion102may be reduced, thereby suppressing degradation in sheet conveying performance of the secondary transfer roller100and degradation in image quality due to unevenness of an electric field in the second transfer area. In addition, as described below, operation efficiency may be increased when the roller attachment part104aof the gripper104is inserted into a roller receiving part provided in the supplementary rotation unit64.

FIG. 6AandFIG. 6Bare appearance perspective diagrams illustrating the supplementary rotation unit64with the secondary transfer roller100attached thereto. InFIG. 6A, the supplementary rotation unit64is viewed from the side of the apparatus body50. InFIG. 6B, the supplementary rotation unit64is viewed from the side of the re-feed path62.

According to the present example embodiment, while the secondary transfer roller100is attached to the supplementary rotation unit64, the roller attachment part104a(shown inFIG. 5) of the gripper104of the secondary transfer roller100is supported with the roller receiving part70(shown inFIG. 8A) provided in the supplementary rotation unit64so as to serve as a grip holding member.

In the apparatus body50, sandwiching members19aand19bare provided at respective positions corresponding to the caps105that are attached to the end portions of the secondary transfer roller100. The sandwiching members19aand19bserve as positioning members to define a position of the secondary transfer roller100on an imaginary plane perpendicular to a swaying direction of the duplexing unit60when the duplexing unit60is closed to the apparatus body50.

Incidentally,FIG. 6Aillustrates only the sandwiching members19aand19bdisposed at the right side of the supplementary rotation unit64. An interval between the sandwiching members19aand19bis extended in a tapered shape in respective fore end portions thereof, and is configured in a parallel shape having an interval length J in accordance with an outer diameter of the cap body105aof the cap105.

When the secondary transfer roller100is attached to the supplementary rotation unit64, the secondary transfer roller100is fixed to the supplementary rotation unit64in a so-called snap-fit manner so that a sheet guide surface of the transfer exit guide101provided in the secondary transfer roller100is in line with the ordinary sheet conveyance path43(refer toFIG. 3) when the duplexing unit60is closed to the apparatus body50.

Further, as illustrated inFIG. 6A, a transfer entrance guide plate68is disposed in a closer side of the supplementary rotation unit64to the apparatus body50and under the secondary transfer roller100. The transfer entrance guide plate68is configured to form a part of the ordinary sheet conveyance path43together with the opposing guide plate (refer toFIGS. 1 and 3, although not numbered) disposed in the side of the apparatus body50.

As illustrated inFIG. 6B, a closer side of the supplementary rotation unit64to the re-feed path62is configured as a conveyance guide surface69having a plurality of ribs69a. The supplementary rotation unit64is also configured to form a part of the re-feed path62together with the opposing guide member66(refer toFIG. 3).

Next, a replacement operation of the secondary transfer roller100is described with reference toFIG. 7.

FIG. 7is an explanatory diagram illustrating an operation direction of the secondary transfer roller100when the secondary transfer roller100is attached to the supplementary rotation unit64.

For a replacement operation of the secondary transfer roller100, first, an operator opens the duplexing unit60from the apparatus body50, and exposes an interior of the supplementary rotation unit64. At this time, the secondary transfer roller100is still attached to the supplementary rotation unit64in the snap-fit manner, as described above.

Then, the operator grips and moves the transfer exit guide101or the gripper104(shown inFIG. 4) toward the apparatus body50, that is, in a direction opposite to a direction indicated by an arrow L inFIG. 7. Thereby, the secondary transfer roller100is detached from the supplementary rotation unit64. Thus, the secondary transfer roller100becomes rotatable while the roller attachment part104aof the gripper104is supported with the roller receiving part70of the supplementary rotation unit64.

Further, the operator rotates the secondary transfer roller100until the sheet guide surface of the transfer exit guide101becomes parallel to a substantially vertical plane. Then, the operator pulls up the secondary transfer roller100in a substantially vertical direction, while gripping the transfer exit guide101or the gripper104. Thereby, the roller attachment part104aof the gripper104is disengaged from the roller receiving part70. Thus, the secondary transfer roller100is detached from the supplementary rotation unit64.

After detaching the secondary transfer roller100from the supplementary rotation unit64, the operator attaches a replacement secondary transfer roller100to the supplementary rotation unit64in a procedure substantially opposite to the above-described detachment procedure.

On attaching the replacement secondary transfer roller100, the operator generally stands facing a side at which the duplexing unit60is disposed in the image forming apparatus200. Therefore, when the operator grips the transfer exit guide101or the gripper104to attach the replacement secondary transfer roller100to the supplementary rotation unit64, the operator looks at the front, towards a surface (i.e. a back surface inFIG. 4) of the replacement secondary transfer roller100that is faced to the supplementary rotation unit64.

Then, while gripping the transfer exit guide101or the gripper104of the replacement secondary transfer roller100, the operator attaches the replacement secondary transfer roller100to the supplementary rotation unit64from an upper side of the supplementary rotation unit64in a vertical direction. Thus, the roller attachment part104aof the gripper104is engaged with the roller receiving part70of the supplementary rotation unit64.

At this time, the operator can see an attachment direction of the replacement secondary transfer roller100to the supplementary rotation unit64by checking the arrow I, which is formed on the marked member105bto indicate the attachment orientation. Also, according to the present example embodiment, the arrow I is provided at an adjacent position of the roller attachment part104athat is engaged with the roller receiving part70of the supplementary rotation unit64. Thereby, the arrow I becomes noticeable to the operator, suppressing overlook thereof.

In addition, according to the present example embodiment, a similar arrow (not illustrated) to the arrow I is provided at an adjacent position of the roller receiving part70of the supplementary rotation unit64. Specifically, the similar arrow is provided at a position opposite to a position at which the arrow I is located in the replacement secondary transfer roller100when the roller attachment part104aof the gripper104is properly engaged with the roller receiving part70of the supplementary rotation unit64.

Accordingly, on attaching the replacement secondary transfer roller100to the supplementary rotation unit64, the operator can engage the roller attachment part104awith the roller receiving part70of the supplementary rotation unit64through properly locating the arrow I and the similar arrow relative to each other. Thus, the replacement secondary transfer roller100can be properly attached to the supplementary rotation unit64.

During the above attachment operation of the replacement secondary transfer roller100, the operator performs the attachment, operation while checking positions of the roller attachment part104aof the gripper104and the roller receiving part70of the supplementary rotation unit64, in addition to positions of the arrow I and the similar arrow.

Accordingly, as in the present example embodiment, providing the arrow I and the similar arrow at respective adjacent positions of the roller attachment part104aand the roller receiving part70may reduce the number of times when the operator changes gaze direction. As a result, operation efficiency may be increased in the replacement operation.

FIGS. 8A and 8Billustrate an engaging point between the roller attachment part104aof the gripper104and the roller receiving part70of the supplementary rotation unit64in the secondary transfer roller100.FIG. 8Ais an enlarged perspective diagram illustrating the roller receiving part70of the supplementary rotation unit64with the secondary transfer roller100detached therefrom.FIG. 8Bis an explanatory diagram illustrating cross-sectional planes of the roller receiving part70and the roller attachment part104a, perpendicular to a rotation axis direction of the roller portion102.

According to the present example embodiment, the roller attachment part104aof the gripper104is attached to the shaft end portion103of the secondary transfer roller100. The roller attachment part104ahas a shape in which two circular arc portions are removed from a member having a circular-shaped cross section and a diameter R′ so that two chords thereof becomes parallel to each other, as illustrated inFIG. 8B.

On the other hand, the roller receiving part70provided in the supplementary rotation unit64has substantially a U-shape in a cross section thereof, as illustrated inFIG. 8B. The U-shape is narrowed in an open portion thereof. An inner space of the U-shape has a shape in which a part of a circular arc is removed from a cross sectional circular having a diameter R slightly larger than a diameter R′, that is, a maximum dimension of the roller attachment part104a.

An opening dimension r of the open portion of the roller receiving part70is configured to be slightly larger than a minimum dimension r′ indicating a distance between the two chords of the roller attachment part104a, and to be sufficiently smaller than the maximum dimension R′ of the roller attachment part134a. Consequently, the roller attachment part104acan be engaged into the roller receiving part70when the roller attachment part104atakes an orientation as illustrated inFIG. 8Brelative to the roller receiving part70.

According to the present example embodiment, when an orientation of the secondary transfer roller100is held so that the sheet guide surface of the transfer exit guide101is parallel to a substantially vertical plane, the roller attachment part104ahas an orientation as illustrated inFIG. 8B. Further, when the duplexing unit60is opened up to a given position, the open portion of the roller receiving part70is oriented upward in a substantially vertical direction, as illustrated inFIG. 8B.

Accordingly, the operator first holds the supplementary rotation unit64of the duplexing unit60, which is opened up to the given position, so that the sheet guide surface of the roller attachment part104abecomes parallel to a substantially vertical plane. Then, the operator moves the secondary transfer roller100to the supplementary rotation unit64so that the roller attachment part104ais inserted into the roller receiving part70from just above the open portion of the roller receiving part70in a substantially vertical direction. Thus, the roller attachment part104aof the secondary transfer roller100is engaged with the roller receiving part70of the supplementary rotation unit64.

The maximum dimension R′ of the roller attachment part104ais configured to be slightly smaller than the minimum dimension R of the inner space of the roller receiving part70, as described above. Therefore, the secondary transfer roller100is rotatable when the roller attachment part104athereof is engaged with the roller receiving part70of the supplementary rotation unit64.

Then, while gripping the transfer exit guide101or the gripper104, the operator rotates the secondary transfer roller100in a direction so that the transfer exit guide101is moved away from the apparatus body50. Further, the operator pushes the transfer exit guide101or the gripper104against the supplementary rotation unit64to fix the secondary transfer roller100to the supplementary rotation unit64in the snap-fit manner. Finally, the operator closes the duplexing unit60relative to the apparatus body50to finish the replacement operation of the secondary transfer roller100.

On attaching the replacement secondary transfer roller100, as described above, the operator performs positioning of the secondary transfer roller100relative to the supplementary rotation unit64so that the arrow I of the secondary transfer roller100and the similar arrow of the supplementary rotation unit64have proper positions relative to each other. In this regard, if no mechanism is provided to support the positioning, the operation efficiency in the above attachment operation may be decreased. Therefore, according to the present example embodiment, the image forming apparatus200is configured to have a positioning mechanism as follows.

FIG. 9is an explanatory diagram illustrating a cross-section of the secondary transfer roller100, which is attached to the supplementary rotation unit64, parallel to the rotation axis direction of the roller portion102.

As illustrated as inFIG. 9, according to the present example embodiment, guide pieces104cand104dare provided for each of the roller attachment parts104aat positions adjacent to an outer side and an inner side, respectively, thereof in the rotation axis direction of the roller portion102. The guide pieces104cand104dsupport the positioning of the secondary transfer roller100relative to the supplementary rotation unit64in the rotation axis direction of the roller portion102.

As in the present example embodiment, the guide pieces104cand104dare preferably disposed so as to be projected from the lower circular-arc portion of the roller attachment part104aillustrated inFIG. 8Boutward in a radial direction of the rotation axis of the roller portion102.

On performing the above positioning, the operator first engages the respective edge portions70a(illustrated inFIG. 8B), which form the open portions of the roller receiving part70in the supplementary rotation unit64, into a space between the guide pieces104cand104d. Thereby, the secondary transfer roller100is positioned relative to the supplementary rotation unit64in the rotation axis direction thereof.

Then, the operator moves the secondary transfer roller100in a direction perpendicular to the rotation axis direction of the roller portion102so as to insert the roller attachment part104aof the secondary transfer roller100into the open portion of the roller receiving part70.

Thus, according to the present example embodiment, the position of the secondary transfer roller100relative to the supplementary rotation unit64in the rotation axis direction of the roller portion102is previously determined with the guide pieces104cand104d. Then, the operator can insert the roller attachment part104ainto the open portion of the roller receiving part70by moving the secondary transfer roller100in a direction perpendicular to the rotation axis direction of the roller portion102.

Therefore, a relatively high operation efficiency may be obtained compared to a case where the operator inserts the roller attachment part104ainto the open portion of the roller receiving part70while performing positioning of the secondary transfer roller100in both of the rotation axis direction of the roller portion102and the direction perpendicular thereto.

As described above, in the present example embodiment, the guide pieces104cand104dare provided for each of the roller attachment parts104aat an outer side and an inner side, respectively, thereof in the rotation axis direction of the roller portion102. However, another configuration may be employed to obtain a similar effect to the present example embodiment.

As another example embodiment, a configuration as illustrated inFIG. 10may be employed. InFIG. 10, the guide pieces104cand104dare provided at an outer side and an inner side of any one of the roller attachment parts104ain the rotation axis direction of the roller portion102. Thereby, similar to the present example embodiment, operation efficiency may be increased in the replacement operation of the secondary transfer roller100.

As another example embodiment, a configuration as illustrated inFIG. 11may be employed. InFIG. 11, the guide pieces104care provided only at each outer side of the roller attachment parts104ain the rotation axis direction of the roller portion102. Thereby, similar to the present example embodiment, operation efficiency may be increased in the attachment operation of the secondary transfer roller100.

Alternatively, although not illustrated, the guide104dmay be provided only at each inner side of the roller attachment parts104ain the rotation axis direction of the roller portion102.

Next, referring toFIG. 12, a replacement package with a secondary transfer roller100packaged therein is described.

FIG. 12is an explanatory diagram illustrating a cross section of a replacement package with a secondary transfer roller100packaged therein, substantially perpendicular to the rotation axis direction of the roller portion102.

A packaging member includes a housing box201and a holding member202. The housing box201houses the replacement secondary transfer roller100therein, and is provided with an extraction mouth201a from which the secondary transfer roller100is taken out. The extraction mouth201ais provided in a plane parallel to the rotation axis direction of the roller portion102. The holding member202holds the housed secondary transfer roller100in an orientation so that upper portions of the transfer exit guide101and the gripper104thereof is directed to the extraction mouth201aof the housing box201.

The housing box201has a rectangular parallelepiped shape that extends longer in a direction parallel to the rotation axis direction of the roller portion102. The housing box201includes a cover part201bto cause the extraction mouth201ato be opened and closed relative to the exterior of the housing box201. According to the present example embodiment, the housing box201is made of corrugated cardboard, which is cut and is folded into a shape as illustrated inFIG. 12. The housing box201may also be made of publicly known materials for a housing box.

The holding member202includes a roller holding part202aand a guide holding part202b. The roller holding part202aholds a lower portion of the roller portion102of the secondary transfer roller100. The guide holding part202blimits a movement of the transfer exit guide101so as to be directed substantially to the extraction mouth. According to the present example embodiment, the holding member202is made of corrugated cardboard, which is cut and is folded into a shape as illustrated inFIG. 12. The holding member202may, however, be made of publicly known materials for a housing box.

On taking out the secondary transfer roller100from the packaging member, the operator opens the cover part201bso that the extraction mouth201ais opened to the exterior of the housing box201. At this time, according to the present example embodiment, the secondary transfer roller100is held with the guide holding part202bof the holding member202in the orientation so that the transfer exit guide101and the gripper104are directed to the extraction mouth201a, as described above. Accordingly, the operator can relatively easily take the secondary transfer roller100out of the housing box201by putting his or her hands through the extraction mouth201ainto the housing box201, gripping and pulling up on the transfer exit guide101or the gripper104.

In addition, according to the present example embodiment, while holding the transfer exit guide101or the gripper104after the extraction, the operator can attach the secondary transfer roller100to the supplementary roller unit64. Therefore, from the extraction of the secondary transfer roller100out of the housing box201, to the attachment thereof to the supplementary roller unit64, the operator does not need to regrip the secondary transfer roller100. Thus, a relatively high operation efficiency may be obtained.

As described above, the image forming apparatus100according to the present example embodiment includes the secondary transfer roller100and the sandwiching members19aand19b. The secondary transfer roller100serves as a roller member attachable to and detachable from the image forming apparatus100. The sandwiching members19aand19bserve as a roller support member to support the shaft end portion103of the secondary transfer roller100via the cap105serving as the roller receiving member.

The secondary transfer roller100also includes the roller portion102, and the two shaft end portions102extended from both ends of the roller portion102outward in the rotation axis direction of the roller portion102. Further, the secondary transfer roller100includes the transfer exit guide101and the gripper104serving as a gripping member that is rotatably provided around the two shaft end portions103.

Accordingly, when performing a replacement operation of the secondary transfer roller100, an operator can handle the secondary transfer roller100while gripping the gripper104or the transfer exit guide101. Thus, attachment of dirt from the operator's hand to a surface of the roller portion102can be reduced, resulting in less deterioration in sheet conveyance performance of the secondary transfer roller100or degradation in image quality due to unevenness in an electric field of the secondary transfer area. Further, a decrease in operation efficiency may be reduced in snapping the roller attachment part104aof the gripper104into the roller receiving part of the supplementary roller unit64.

Furthermore, according to the present example embodiment, the grippers104and the transfer exit guide101may be a single member rotatably provided around the two shaft end portions103. If gripping members are separately provided around each of the two shaft end portions103, rotated positions of the gripping members may be different from each other, causing delay in the operator's handling thereof. Compared to this, according to the present example embodiment, such a difference between rotated positions of the gripping members does not occur, resulting in efficient handling of the secondary transfer roller100.

Moreover, according to the present example embodiment, the roller member subjected to the replacement operation is configured to be used as the secondary transfer roller100serving as a conveyance roller to convey a sheet by contacting one surface of the sheet when the secondary transfer roller100is attached to the image forming apparatus200.

The transfer exit guide101is used as the gripping member. The transfer exit guide101also serves as a conveyance regulation member to regulate a conveyance direction of the sheet by contacting the sheet during conveyance when the secondary transfer roller100is attached to the apparatus body50.

Conventionally, from a viewpoint of downsizing the apparatus, since the gripping member is not related to the image forming operation of the image forming apparatus200, the size of the gripping member of the secondary transfer roller100is preferably smaller. However, a smaller size of the gripping member may reduce operability of the secondary transfer roller100in the replacement operation thereof.

Then, according to the present example embodiment, the transfer exit guide101having a relatively large size corresponding to a sheet size is used as the gripping member of the secondary, transfer roller100that is gripped when the secondary transfer roller100is attached to the image forming apparatus200. Thereby, the downsizing of the image forming apparatus200and the operability of the secondary transfer roller100can go together.

Incidentally, in the above description of the present example embodiment, the secondary transfer roller100is explained as a roller member subjected to the replacement operation. However, the roller member subjected to the replacement operation may be another roller member, and may be a drive roller or a driven roller.

In addition, according to the present example embodiment, the transfer exit guide101may be made of ABS resin, resulting in a less fragile property and a relatively high operability in handling the transfer exit guide101.

Incidentally, as explained in the above description of the present example embodiment, the transfer exit guide101is preferably made of a resin that does not contain any butadiene component.

In the secondary transfer roller100according to the present example embodiment, the cap105is attached to at least one of the two shaft end portions103. The cap105serves as the cap-shaped shaft bearing member that may slidably move along an outer circumferential surface of the two shaft end portions103. The cap105is fixed with the sandwiching members19aand19bof the apparatus body50when the secondary transfer roller100is attached to the apparatus body50.

The secondary transfer roller100also includes the sandwiching members104band the connecting member105cto fix the cap105to the roller attachment part104aof the gripper104. The configuration as described above can suppress unintentional detachment of the cap105from the shaft end portion103.

Further, according to the present example embodiment, the cap105may be a resin member having an inner circumferential surface that is slidably moved around the shaft end portion103with a relatively low frictional force. Therefore, a cap capable of being smoothly rotated around the shaft end portion103may be produced at a relatively lower cost.

The above fixing members according to the present example embodiment include the connecting member105cand the sandwiching members104b. The connecting member105cserving as an engaging part is projected from the outer circumferential surface of the cap105to a radial direction thereof.

The sandwiching members104b, serving as an engaged part, is disposed in an outer side of each of the roller attachment parts104aof the grippers104in the rotation axis direction of the roller portion102. The connection member105cmay be configured to be sandwiched with the sandwiching members104bwhen the connecting member105cis engaged into the sandwiching members104bfrom an outer side thereof in the rotation axis direction of the roller portion102.

With the configuration as described above, an operator can attach the cap105to the shaft end portion103through a simple operation of engaging the connecting member105cof the cap105into the sandwiching members104bfrom the external side in the rotation axis direction of the roller portion102. Further, the manufacturing process of the secondary transfer roller100may be simplified, resulting in an increase in productivity thereof.

Incidentally, a similar effect may be obtained with a configuration in which sandwiching members serving as an engaged part are disposed in the cap105, and an engaging part to be sandwiched with the sandwiching members is disposed in the roller attachment part104a.

The above fixing member may be configured to be a screw member107as illustrated inFIG. 13. The screw member107screws the cap105onto the roller attachment part104aof the gripper104, thereby further suppressing unintentional detachment of the cap105from the shaft end portion103.

According to the present example embodiment, the cap105includes the marked member105bindicating an attachment direction in which the secondary transfer roller100is attached to the apparatus body50. Thus, mistakes regarding the attachment direction may be reduced, and operation efficiency in the replacement operation may be increased.

In addition, according to the present example embodiment, the apparatus body50has another marked member which corresponds to the marked member105bdisposed at the cap105when the secondary transfer roller100is attached to the apparatus body50. Therefore, the marked member105bof the cap105may also indicate an attachment position at which the secondary transfer roller100is attached to the apparatus body50. With the marked member105b, mistakes of the attachment position may be reduced, and operation efficiency in the replacement operation may be increased.

For the marked member105bindicating the attachment position of the secondary transfer roller100, as illustrated inFIG. 14, an arrow M directed to an inner side in the rotation axis direction of the roller portion102may be employed as a mark formed on the marked member105b. Thereby, mistakes of the attachment position may be effectively reduced, and operation efficiency in the replacement operation may be further increased.

In the above description of the present example embodiment, the secondary transfer roller is supported with the apparatus body50in a manner such that the rotatable cap105, which is slidably moved around the shaft end portion103, is sandwiched with the sandwiching members19aand19bdisposed in the apparatus body50. However, the secondary transfer roller may be supported with the apparatus body50in another manner.

For example, a shaft bearing member108including a ball bearing as illustrated inFIG. 15may be employed instead of the cap105. The inner circumferential surface of the shaft bearing member108is fixed to at least one of the shaft end portions103. On the other hand, the outer circumferential surface of the shaft bearing member108is fixed with the sandwiching members19aand19bof the apparatus body50when the secondary transfer roller100is attached to the apparatus body50.

In this case, a load applied between the shaft end portion103and the sandwiching members19aand19bduring rotation may be reduced. Therefore, a relatively smooth rotation of the shaft end portion103may be obtained while the secondary transfer roller100is attached to the apparatus body50.

Further, in another example embodiment illustrated inFIG. 15, the shaft bearing member108is attached to the shaft end portion103by press-fit fixation. Therefore, operation efficiency may be increased in attaching the shaft bearing member108to the shaft end portion103. As a result, the productivity of the secondary transfer roller100may be increased.

In addition, as illustrated inFIG. 16, a collar member109may be provided so as to be attached onto an outer surface of the shaft bearing member108from an outer side thereof in the rotation axis direction of the roller portion102. The collar member109has a cylindrical shape and an opening formed on one end face of the front side thereof inFIG. 16. Further, a fixing member may be provided to fix the cylindrical collar member109to the roller attachment part104aof the gripper104.

The collar member109also has a similar configuration to the cap105of the present example embodiment except for a difference in diameter. Accordingly, similar to the present example embodiment, the fixing member of the collar member109also includes a connecting member109cand sandwiching members104b. The connecting member109cis projected from an outer circumferential surface of the collar member109outward in a radial direction thereof, and serves as an engaging part. The sandwiching members104bare disposed on an outer side of the roller attachment part104aof the gripper104in the rotation axis direction of the roller portion102, and serves as an engaged part. The connecting member109cmay be configured to be sandwiched with the sandwiching members104bwhen the connecting member109cis put into the sandwiching members104bfrom an outer side thereof in the rotation axis direction of the roller portion102.

When the configuration as illustrated inFIG. 16is employed, the shaft bearing member108is first attached into the collar member109, and then the shaft end portion103is inserted into an inner circumferential space of the shaft bearing member108. Further, the connecting member109bof the collar member109is engaged into the sandwiching members104bof the roller attachment part104a.

Thus, the shaft bearing member108can be attached to the shaft end portion103. The above attachment operation may be relatively simply accomplished, compared to the attachment operation in which the shaft bearing member108is attached to the shaft end portion103by press-fit fixation. Therefore, the productivity of the secondary transfer roller100may be further increased.

Incidentally, similar to the example embodiment illustrated inFIG. 13, when the fixing member is configured to be a screw member to screw the collar member109onto the roller attachment part104aof the gripper104, unintentional detachment of the collar member109from the secondary transfer roller100may be suppressed.

According to the present example embodiment, the packaging member of the replacement for the secondary transfer roller100includes the housing box201and the holding member202. In the housing box201, the extraction mouth201ais formed so that the replacement secondary transfer roller100can be extracted therefrom. The holding member202holds the replacement secondary transfer roller100that is housed in the housing box201in an orientation so that the gripper104or the transfer exit guide101of the replacement secondary transfer roller100is directed to the extraction mouth201a.

Accordingly, in the replacement operation of the secondary transfer roller100, an operator can extract the replacement secondary transfer roller100from the housing box201while griping the gripper104or the transfer exit guide101thereof. As a result, opportunities may be reduced in which dirt from the operator's hand is attached to a surface of the roller portion102, thereby suppressing deterioration in sheet conveyance performance of the secondary transfer roller100or degradation in image quality due to unevenness in an electric field of the secondary transfer area. Further, a decrease in operation efficiency may be reduced when the roller attachment part104aof the gripper104attached to the shaft end portion103is engaged into the roller receiving part70of the supplementary roller unit64.

In the image forming apparatus200according to the present example embodiment, the apparatus body50is provided with the roller receiving part70serving as the gripper holding member to hold the gripper104or the transfer exit guide101of the secondary transfer roller100. The gripper104of the secondary transfer roller100includes the roller attachment part104aserving as the held part that is held by the roller receiving part70.

The roller attachment part104ahas a shape as illustrated inFIG. 8B, having different lengths R′ and r′ from each other in two directions perpendicular to a plane including the rotation axis direction of the roller portion102.

The roller receiving part70includes an open portion serving as a receiving mouth for the roller attachment part104a. The open portion has a dimension corresponding to a minimum length r′ in a direction perpendicular to a roller axis direction of the roller attachment part104a.

Only when the roller attachment part104ais oriented relative to the open portion of the roller receiving part70as illustrated inFIG. 8B, can the roller attachment part104abe engaged into the roller receiving part70, and the secondary transfer roller100be attached to the supplementary rotation unit64. Regulating the attachment direction as above may effectively suppress improper attachment of the secondary transfer roller100to the supplementary rotation unit64.

According to the present example embodiment, the roller attachment part104amay be configured as an attachment part of the gripper104used when the gripper104is attached to each of the shaft end portions103disposed at an outer side of the roller portion102in the rotation axis direction of the roller portion102.

The guide pieces104cand104dare disposed at an outer adjacent area and at an inner adjacent area of the roller attachment part104ain the rotation axis direction of the roller portion102. The guide pieces104cand104dcontact an outer side and an inner side of the edge portions70a, forming the open portion in the roller axis direction of the roller portion102. Thereby, the guide pieces104cand104dguide insertion of the roller attachment part104ainto the open portion of the roller receiving part70.

Thus, with the guide pieces104cand104d, the position of the secondary transfer roller100is previously determined relative to the supplementary rotation unit64in the rotation axis direction of the roller portion102. Under this condition, the positioning of the secondary transfer roller100is performed with respect to a direction perpendicular to the rotation axis direction of the roller portion102.

Then, the roller attachment part104acan be inserted into the open portion of the roller receiving part70. Therefore, according to the present example embodiment, a relatively higher operation efficiency may be obtained compared to the case where the roller attachment part104ais inserted into the open portion of the roller receiving part70while the positioning of the secondary transfer roller100is simultaneously performed in both the rotation axis direction of the roller portion102and a direction perpendicular thereto.

The image forming apparatus200according to the present example embodiment includes the duplexing unit60and the link mechanism. The duplexing unit60is disposed on the side surface of the apparatus body50, and also serves as an openable and closable door relative to the upper area of the apparatus body50. The link mechanism serves as a door holding member to hold the duplexing unit60in an opened position.

The roller receiving part70is disposed on an inner surface of the duplexing unit60, facing the apparatus body50. The roller receiving part70is also disposed so that the open portion of the roller receiving part70is oriented substantially vertically upward when the duplexing unit60is opened via the link mechanism.

Generally, the metal core is the heaviest portion in the secondary transfer roller100. Accordingly, when the gripper104or the transfer exit guide101is gripped, the secondary transfer roller100is preferably held in such an orientation that the roller portion102is placed at the lowest position thereof. Thereby, the secondary transfer roller100can be handled with a relatively low effort. Thus, in the image forming apparatus200according to the present example embodiment, the secondary transfer roller100can be attached to the supplementary rotation unit64with a relatively low effort.