This patent application is based on and claims priority pursuant to 35 U.S.C. § 119(a) to Japanese Patent Application No. 2019-024962, filed on Feb. 15, 2019, in the Japan Patent Office, the entire disclosure of which is hereby incorporated by reference herein.
Embodiments of the present disclosure relate to an image forming apparatus.
Image forming apparatuses generally include an image bearer, such as a photoconductor drum and an intermediate transfer belt, and a transferor, such as a transfer roller. The transferor is pressed against the image bearer to form a transfer nip. In the image forming apparatuses, a toner image formed on the image bearer is transferred onto a recording sheet transported through the transfer nip between the transfer roller and an opposed roller by applying a transfer bias to the transfer roller or the opposed roller.
In such image forming apparatuses, there is known a configuration in which, when a cover of the apparatus is open, a drum unit is removably installable through an opening. A user can remove a sheet jammed in a passage of sheets and replace the transfer roller and the drum unit through the opening.
Further, to replace the transfer roller, a configuration is known in which a conveyance guide that guides the recording sheet to the transfer nip is provided with an arm that supports the transfer roller, and the conveyance guide is movable. As a user moves the conveyance guide, the transfer roller can be moved from the position at the time of image formation to the position where the user can easily replace the transfer roller, thereby facilitating removal of the transfer roller.
Such a conveyance guide guides the transfer roller from a temporary setting position where the user initially sets the transfer roller on the conveyance guide to a setting completion position (regular position) where the transfer roller is precisely positioned in the apparatus.
Embodiments of the present disclosure describe an improved image forming apparatus that includes an apparatus body, an image bearer, and a rotator opposed to the image bearer. The rotator is removably installable in the apparatus body. The image forming apparatus further includes a guide configured to guide the rotator in a longitudinal axial direction of the rotator toward a regular position where the rotator is installed in the apparatus body.
A more complete appreciation of the disclosure and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:
The accompanying drawings are intended to depict embodiments of the present disclosure and should not be interpreted to limit the scope thereof. The accompanying drawings are not to be considered as drawn to scale unless explicitly noted. In addition, identical or similar reference numerals designate identical or similar components throughout the several views.
In describing 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 have the same function, operate in a similar manner, and achieve a similar result.
As used herein, the singular forms “a”, “an”, and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise.
A process cartridge 2 is disposed in a substantially center part of an apparatus body 1 of the image forming apparatus 100. The process cartridge 2 includes a photoconductor drum 3, an exposure device 4, and a developing device 5. A charging device 6, which is a charging roller in the present embodiment, is pressed against a surface of the photoconductor drum 3 and rotated along with rotation of the photoconductor drum 3. A high-voltage power source applies a bias to the charging device 6, thereby charging the surface of the photoconductor drum 3 uniformly. The bias can be a direct-current (DC) voltage or a superimposed voltage in which an alternating-current (AC) voltage is superimposed on the DC voltage.
The exposure device 4 disposed above the photoconductor drum 3 exposes the photoconductor drum 3 based on image data, thereby forming an electrostatic latent image on the surface of the photoconductor drum 3. This exposure process is performed by, for example, a laser beam scanner using a laser diode or light-emitting diode (LED) arrays. The developing device 5 includes a developing roller 7 that causes toner to adhere to the photoconductor drum 3 and develops the electrostatic latent image formed on the photoconductor drum 3 with toner into a toner image. The photoconductor drum 3, the developing device 5, and the charging device 6 are integral parts of a drum unit 10 that is removably installable in the apparatus body 1.
The transfer roller 20 as a rotator is disposed below the photoconductor drum 3 and forms a transfer portion (transfer nip) between the photoconductor drum 3 and the transfer roller 20. A high voltage is applied to the transfer roller 20, and the toner image formed on the surface of the photoconductor drum 3 is transferred to a recording sheet as a recording medium due to a potential difference between the photoconductor drum 3 and the transfer roller 20. In addition, the transfer roller 20 constitutes a conveyance unit 24 together with a conveyance guide 26 to guide the recording medium to the transfer portion. The conveyance unit 24 also functions as a transfer unit. Alternatively, instead of the transfer roller 20, a transfer belt may be used as the rotator. Further, a transfer charger that applies reverse charges opposite to toner in polarity may be used instead of the transfer roller 20.
A fixing device 8 applies heat and pressure to the recording sheet bearing the toner image to fix the toner image on the recording sheet while passing the recording sheet between two rollers of the fixing device 8. The image forming apparatus 100 includes a sheet sensor disposed on a conveyance path from the fixing device 8 to a sheet ejection device 9 to confirm a state of the recording sheet, such as the arrival time of the leading edge, the passage time, and the position of the recording sheet on the conveyance path.
The image forming apparatus 100 includes a sheet tray 11 disposed below the transfer roller 20 and at the lower part of the image forming apparatus 100, to store a stack of recording sheets. The sheet feeding device 12 picks up a recording sheet one by one from the sheet tray 11 and transports to the transfer portion between the photoconductor drum 3 and the transfer roller 20. Then, the recording sheet is ejected to an output tray via the transfer portion and the fixing device 8.
A rear cover 14 is disposed on the right side of the image forming apparatus 100 in
Further, a front cover 16 is disposed on the left side of the image forming apparatus 100 in
With such a configuration, image formation is performed in the image forming apparatus 100 as follows. The sheet feeding device 12 transports a recording sheet, which is picked up from the sheet tray 11, via a registration roller pair 17 to the transfer portion between the photoconductor drum 3 and the transfer roller 20. After the toner image is transferred to the recording sheet, the recording sheet is transported to the fixing device 8 to fix the toner image on the recording sheet. After the toner image is fixed thereon, the recording sheet is ejected to the output tray on the upper face of the image forming apparatus 100 by the sheet ejection device 9.
As described above, the image forming apparatus 100 includes the apparatus body 1 as a housing. The drum unit 10 is removably installable through the opening 15 of the apparatus body 1 when the front cover 16 is open. A description is given below of a configuration to install the drum unit 10.
As illustrated in
When the drum unit 10 is installed in the apparatus body 1, the guided portion 10a is placed on the guide section 19 and slid, thereby guiding the drum unit 10. As a result, the drum unit 10 is pushed into a predetermined position of the apparatus body 1 (i.e., above the conveyance unit 24 as illustrated in
In
Next, a description is given below of the conveyance unit (transfer unit) 24 including the transfer roller 20 disposed opposite the drum unit 10.
The conveyance guide 26 has substantially the same width as the transfer roller 20 in the longitudinal axial direction, and the arms 25 disposed at both ends of the conveyance guide 26 support the rotary shaft 20a of the transfer roller 20. The arms 25 and the conveyance guide 26 are rotatable around the rotation fulcrum 27. The transfer roller 20 is supported downstream from the conveyance guide 26 in the conveyance direction, and the rotation fulcrum 27 of the conveyance guide 26 is disposed upstream from the conveyance guide 26 in the conveyance direction. The lever 28 is disposed between the transfer roller 20 and the rotation fulcrum 27.
The rotation fulcrum 27 is supported by the apparatus body 1 so that the conveyance unit 24 is movable. As a user grips the lever 28 and moves (rotates) the conveyance guide 26 in the direction indicated by arrow a in
On the other hand, at the time of printing, it is necessary to position and secure the conveyance guide 26 at a regular position for printing, that is, the position where the conveyance guide 26 can stably transport a recording medium to the transfer portion.
As illustrated in
Next, a description is given below of a configuration to install the transfer roller 20 in the apparatus body 1 according to the present embodiment.
The image forming apparatus 100 includes the photoconductor drum 3 as an image bearer and the transfer roller 20 as a rotator that is removably installable in the apparatus body 1. The transfer roller 20 is opposed to the photoconductor drum 3, thereby forming the transfer portion. The image forming apparatus 100 further includes sliding bearings 23 and guide faces 23a on the sliding bearings 23 that are a guide to guide the transfer roller 20 in the longitudinal axial direction toward the regular position where the transfer roller 20 is installed in the apparatus body 1. As a result, the transfer roller 20 can be installed in the image forming apparatus 100 without a setting failure.
As illustrated in
The transfer roller 20 includes end rollers 21 as rolling elements at both ends in the longitudinal axial direction, and the sliding bearings 23 have the guide faces 23a to guide the end rollers 21 respectively in the longitudinal axial direction when the transfer roller 20 is installed. As a result, the transfer roller 20 is properly set without getting stranded on the edge of the sliding bearing 23 when the transfer roller 20 is installed, and the setting failure is prevented. The guide face 23a is formed so that the deviation of the transfer roller 20 in the longitudinal axial direction from the regular position of the transfer roller 20 can be eliminated. The guide face 23a is disposed on the upper face of the sliding bearing 23 upstream from the rotary shaft 20a of the transfer roller 20 in the conveyance direction when the transfer roller 20 is properly set. Alternatively, the guide face 23a may be disposed on the sliding bearing 23 downstream from the rotary shaft 20a of the transfer roller 20 in the conveyance direction. Note that the guide face 23a may be disposed on the frame 29 near the sliding bearing 23, or may be united with the frame 29 and the sliding bearing 23 as a single piece.
The end roller 21 is an example of a gap forming member that forms a gap between the photoconductor drum 3 and the transfer roller 20.
The image forming apparatus 100 includes the arms 25 of the conveyance guide 26 as the guide member to guide the transfer roller 20 from the temporary setting position where a user sets the transfer roller 20 toward the regular position. User convenience is improved because the user can rotate the arm 25 of the conveyance guide 26 to guide the transfer roller 20. That is, the conveyance guide 26, which serves as a guide member for recording media to guide the recording medium to the transfer portion in the conveyance direction, rotates together with the arm 25 provided on the conveyance guide 26 when the transfer roller 20 is installed. In addition, the conveyance guide 26 also serves as a guide member for the transfer roller 20 to guide the transfer roller 20 in the conveying direction (direction perpendicular to the axis of the transfer roller 20) toward the sliding bearing 23.
The precision with which the transfer roller 20 is positioned at the temporary setting position is less precise than the precision with which the transfer roller 20 is positioned at the regular position, so that a user can easily set the transfer roller 20 at the temporary setting position.
A conveyance guide 26 as a guide member guides a recording medium to the transfer portion. The conveyance guide 26 has a guide function, and the conveyance path of the recording medium is formed so that the transfer roller 20 and the leading end of the conveyance guide 26 are close to each other. Thus the conveyance path communicates with the transfer portion. Therefore, stable transfer quality can be obtained.
With reference to
As illustrated in
Subsequently, as the conveyance guide 26 rotates around the rotation fulcrum 27 toward the sliding bearing 23, as illustrated in
As the conveyance guide 26 further rotates toward the sliding bearing 23 around the rotation fulcrum 27, as illustrated in
As the conveyance guide 26 further rotates toward the sliding bearing 23 around the rotation fulcrum 27, as illustrated in
Thereafter, the large-diameter portion 21a of the end roller 21 is used for contacting the photoconductor drum 3 to be positioned relative to the photoconductor drum 3, and the end roller 21 is rotated along with the rotation of the photoconductor drum 3. As a result, the photoconductor drum 3 stably rotates while maintaining a gap between the transfer roller 20 and the photoconductor drum 3.
In the transition state in
With reference to
The sliding bearings 23 including the guide face 23a are disposed at both ends of the transfer roller 20. As a result, the transfer roller 20 is movable toward the rear side and the front side of the image forming apparatus 100 in the longitudinal axial direction.
As described above, according to the present disclosure, the sliding bearing 23 includes the guide face 23a disposed on the trajectory on which the transfer roller assembly 22 moves from the temporary setting position to the regular position when the transfer roller assembly 22 or the transfer roller 20 is installed in the apparatus body 1. The guide face 23a that contacts the transfer roller assembly 22 guides the transfer roller assembly 22 to the regular position. Thus, even if a user initially places the transfer roller assembly 22 on the conveyance guide 26 at the temporary setting position, the setting failure does not occur.
As a result, according to the present disclosure, a rotator can be installed in the apparatus body without the setting failure.
The above-described embodiments are illustrative and do not limit the present disclosure. Thus, numerous additional modifications and variations are possible in light of the above teachings. For example, elements and/or features of different illustrative embodiments may be combined with each other and/or substituted for each other within the scope of the present disclosure.
Moreover, the image forming apparatus is not limited to a copier or a printer. Alternatively, the image forming apparatus may be a facsimile machine or a multifunction peripheral having a plurality of functions, such as copying, printing, and facsimile communication. Further, the present disclosure may be applied to an image forming apparatus employing an intermediate transfer method. The direction in which the sheet is conveyed at the transfer portion and the direction in which the drum unit is removably installed in the apparatus body are not limited to the horizontal direction, but may be oblique or vertical direction.
Number | Date | Country | Kind |
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2019-024962 | Feb 2019 | JP | national |
Number | Name | Date | Kind |
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Number | Date | Country |
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Entry |
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U.S. Appl. No. 16/655,593, filed Oct. 17, 2019, Naoki Takai. |
Number | Date | Country | |
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20200264540 A1 | Aug 2020 | US |