JP5277188B2 - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus that can easily ensure alignment accuracy with a simple configuration and can stably convey transfer paper. <P>SOLUTION: The image forming apparatus includes: a pair of resist rollers disposed, in a transfer-paper conveyance direction, upstream of a transfer section that is disposed on the way to a conveyance path on which transfer paper is conveyed in an upper direction; a side-surface panel provided on the side surface of an apparatus body 12; a pre-transfer guide forming the conveyance path between the pair of resist rollers and the transfer section; a separating mechanism section for separating one resist roller 69 and a transfer roller 44 from the other resist roller and a photoreceptor drum in conjunction with an opening operation for the side-surface panel; and a single positioning member 77 provided in the apparatus body 12 and used for positioning one resist roller 69, the transfer roller 44, at least each transfer-paper conveyance direction of one pre-transfer guide 83, and a transfer-paper width direction. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a transfer unit that is disposed in the middle of a conveyance path for conveying a transfer paper taken out from a paper supply unit upward in the vertical direction of the apparatus main body, and includes an image carrier and a transfer roller. The present invention relates to an image forming apparatus provided with a pair of registration rollers disposed on the upstream side in the transport direction, and a side panel provided on a side surface of the apparatus main body and opening a part of the side surface.

  2. Description of the Related Art Conventionally, there is known an image forming apparatus that takes out transfer paper stored in a paper feed cassette or a paper feed tray from a paper feed unit, and executes an image forming process in the middle of conveying the transfer paper upward in the vertical direction of the apparatus main body. ing.

  In addition, in an image forming apparatus that executes image forming processing while conveying such transfer paper upward in the vertical direction of the apparatus main body, a wall panel having a cover function that forms a part of the outer wall surface of the apparatus main body. It is common to perform JAM processing of transfer paper by opening.

  At this time, in order to remove the transfer paper jammed in the vicinity of the registration roller pair and the transfer portion, the JAM process can be easily performed if the nip state of the transfer paper at the registration roller pair or the transfer portion is released. Therefore, the roller disposed on the wall panel side such as one side of the transfer roller or the registration roller pair of the transfer unit is a device such as the image carrier of the transfer unit or the other side of the registration roller pair during the opening operation of the wall panel. It is effective to separate from the roller or the like on the inside of the main body.

  Therefore, a configuration is known in which these members are configured in a unit shape and interlocked with the opening operation of the wall surface panel (see, for example, Patent Document 1).

  When these are unitized, the JAM process can be performed more easily by opening the pivot point of the wall panel upward as the lower side of the apparatus main body.

JP 2003-186269 A

  However, in the above-described image forming apparatus, when the wall panel is closed after the JAM processing, the relative position of the unit-side component to the apparatus main body, for example, transfer paper conveyance with respect to the apparatus main body of the pair of registration rollers There has been a problem that it is difficult to easily secure the alignment accuracy such as the positioning in the direction (vertical direction) and the transfer paper width direction, and the spacing between the rollers and the like on the apparatus main body side.

  In particular, in a large apparatus main body associated with a large-size transfer paper size (for example, A3 compatible) etc., there is a tendency for the conveyance path to be longer between the registration roller pair and the transfer unit, and a guide for forming this conveyance path. When a plate or the like is disposed, the number of parts that need to be aligned increases, so it is desirable to further easily ensure alignment accuracy.

  In addition, when the alignment accuracy is low, coupled with the fact that the transfer paper is transported upward against gravity, not only causes skew of the transfer paper in the apparatus body, but also causes frequent JAM. There has also been a problem that it is likely to cause various problems such as occurrence and breakage of the transfer paper.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus that can easily ensure alignment accuracy with a simple configuration and can stably convey transfer paper.

  An image forming apparatus according to the present invention includes a transfer unit that is disposed in the middle of a conveyance path for conveying a transfer sheet taken out from a paper feeding unit upward in the vertical direction of the apparatus body, and includes an image carrier and a transfer roller, and the transfer unit A pair of registration rollers disposed on the upstream side in the transfer paper conveyance direction, a transfer conveyance unit provided along the side surface of the apparatus main body and opening a part of the transfer portion from the side surface of the registration roller pair; In the image forming apparatus, the transfer conveyance unit includes the transfer roller and one of the registration roller pair, and forms a conveyance path between the registration roller pair and the transfer unit. One of a pair of pre-transfer guides for guiding the front and back of the transfer paper, and the one registration roller and the transfer roller are connected to the registration roller in conjunction with the opening operation of the transfer conveyance unit. A separation mechanism that separates the other of the pair from the image carrier, and at least each transfer paper transport of the one registration roller, the transfer roller, and the other of the pre-transfer guides in the apparatus main body. A single positioning member for positioning the direction and the transfer paper width direction is provided.

  At this time, the positioning member is made of a resin, and a registration roller positioning portion that engages with both end portions of the one registration roller to position the transfer paper conveyance direction and the transfer paper width direction; and both end portions of the transfer roller; A transfer roller positioning portion that engages to position the transfer paper conveyance direction and the transfer paper width direction, and a guide positioning that engages the other end portions of the pre-transfer guide and positions the transfer paper conveyance direction and the transfer paper width direction. And a guide abutting surface that defines a facing interval between the guides by contacting the transfer paper conveyance path surface of the one pre-transfer guide.

  The registration roller positioning unit and the transfer roller positioning unit are urging members that urge the one registration roller and the transfer roller toward the other registration roller and the image carrier side independently. The opposing distance is defined by urging, and the separation mechanism unit moves the one registration roller and the transfer roller from the other registration roller and the image carrier against the urging of the urging member. It is preferable to separate them.

  The image forming apparatus of the present invention can easily ensure alignment accuracy with a simple configuration, and can stably convey transfer paper.

1 is an explanatory diagram of a multifunction peripheral as an image forming apparatus according to an embodiment of the present invention. FIG. 1 is a perspective view of a side panel applied to an image forming apparatus according to an embodiment of the present invention. 1 is a cross-sectional view of a main part of an image forming apparatus according to an embodiment of the present invention when a side panel is open. 1 is an enlarged cross-sectional view of a main part of an image forming apparatus according to an embodiment of the present invention in a side panel open state. 1 is an explanatory diagram of a main part of an image forming apparatus according to an embodiment of the present invention. 1 is a perspective view of a main part in a locked state of a side panel applied to an image forming apparatus according to an embodiment of the present invention. FIG. 3 is a perspective view of a main part in an unlocked state of a side panel applied to the image forming apparatus according to the embodiment of the present invention. (A) is a side view of a locked state of a side panel applied to an image forming apparatus according to an embodiment of the present invention, and (B) is a side panel of a side panel applied to an image forming apparatus according to an embodiment of the present invention. It is a side view of an unlocked state. (A) is a perspective view of a transfer conveyance unit applied to an image forming apparatus according to an embodiment of the present invention, and (B) is a transfer of a transfer conveyance unit applied to an image formation apparatus according to an embodiment of the present invention. It is a perspective view in the state where a roller unit was removed. FIG. 3 is a cross-sectional view of a transfer conveyance unit in the image forming apparatus according to an embodiment of the present invention. 3 is a cross-sectional view of a main part of a transfer conveyance unit in an image forming apparatus according to an embodiment of the present disclosure. FIG. FIG. 3 is an enlarged cross-sectional view of a main part of a transfer conveyance unit in an image forming apparatus according to an embodiment of the present invention. 2 is a perspective view of a transfer roller unit in the image forming apparatus according to the embodiment of the present disclosure. FIG. 1 is a perspective view of a main part on the apparatus main body side in an image forming apparatus according to an embodiment of the present invention. FIG. 3 is a cross-sectional view of a main part in a transfer unit support state in the image forming apparatus according to the embodiment of the present disclosure. FIG. 4 is a perspective view of a main part in a transfer unit support state in the image forming apparatus according to the embodiment of the present disclosure. FIG. 3 is a front view of one side of a unit fixing resin member applied to the image forming apparatus according to the embodiment of the present invention. It is a perspective view of one side of a unit fixing resin member applied to an image forming apparatus according to an embodiment of the present invention. It is a front view of the other side of the resin member for unit fixation applied to the image forming apparatus which concerns on one Embodiment of this invention. It is a perspective view of the other side of the resin member for unit fixation applied to the image forming apparatus concerning one embodiment of the present invention. FIG. 6 is a perspective view of the other side of the pre-transfer surface side guide support state of the unit fixing resin member applied to the image forming apparatus according to the embodiment of the present invention. FIG. 6 is a perspective view of one side of a pre-transfer surface side guide support state of a unit fixing resin member applied to an image forming apparatus according to an embodiment of the present invention. FIG. 4 is a perspective view of one side showing a relationship between a unit fixing resin member and a pre-transfer surface side guide applied to the image forming apparatus according to the embodiment of the present invention. FIG. 5 is a perspective view of the other side showing a relationship between a unit fixing resin member and a pre-transfer surface side guide applied to the image forming apparatus according to the embodiment of the present invention.

  Next, an image forming apparatus according to an embodiment of the present invention will be described with reference to the drawings. The following embodiments are preferred specific examples of the image forming apparatus according to the present invention, and may have various technically preferable limitations. However, the technical scope of the present invention particularly includes the present invention. As long as there is no description which limits, it is not limited to these aspects.

(Overall configuration of multifunction machine 11)
In FIG. 1, reference numeral 11 denotes a multifunction machine 11 as an image forming apparatus having functions of a copying machine, a printer, a facsimile machine, and a scanner.

  An MFP 11 as an image forming apparatus according to an embodiment of the present invention includes an apparatus main body 12, a paper feed cassette 13 that can be pulled out from the front surface of the apparatus main body 12, and transfer paper (not shown) stored in the paper feed cassette 13. In order to make it possible to use transfer paper (not shown) different from the paper tray, a manual feed tray 14 that can be opened and closed on one side surface of the apparatus main body 12 and various functions of a copying machine, a facsimile machine, and a scanner. An automatic document feeder (ADF) 15 used when reading a document and an operation unit 16 for setting / selecting various functions and the like are provided. Note that the shape, configuration, function, and the like of the multifunction machine 11 are not limited to those illustrated.

(Internal configuration of the apparatus body 12)
Further, inside the apparatus main body 12, a paper feed conveyance path 18 that takes out the transfer paper stored in the paper feed cassette 13 and conveys it to the paper discharge tray 17, and an upstream of the paper feed conveyance path 18 in the transfer paper conveyance direction. A pair of registration rollers 19 disposed on the side, an image forming unit 20 disposed on the downstream side of the sheet feeding conveyance path 18 in the transfer paper conveyance direction with respect to the registration roller pair 19, and transfer to the surface of the transfer paper by the image formation unit 20 A fixing unit 21 for fixing the toner image on the surface of the transfer paper; and a discharge unit 22 disposed at the most downstream portion in the apparatus main body 12 of the paper feed conveyance path 18.

  Further, a plurality of paths are branched and merged in the paper feed conveyance path 18, and in this embodiment, the transfer paper supplied from the manual feed tray 14 at the most upstream side of the paper feed conveyance path 18 in the transfer paper conveyance direction. , A branch path 24 arranged on the downstream side of the sheet feeding conveyance path 18 in the transfer sheet conveyance direction with respect to the fixing unit 21, and a transfer sheet led to the branch path 24 in the case of duplex printing. A switchback path 25 for reversing the front and back, and a reversal path 26 for returning the transfer paper that has been turned upside down by the switchback path 25 to the paper feed conveyance path 18 on the upstream side of the registration roller pair 19 in the transfer paper conveyance direction. Yes.

(Configuration of registration roller pair 19)
The registration roller pair 19 detects the leading edge position of the transfer paper and the image forming unit 20 by detecting the leading edge of the transfer paper taken out from the paper feed cassette 13 or the manual feed tray 14 with a registration sensor (not shown). The position of the toner image formed on the surface of the photosensitive drum 27 is synchronized with the position of the toner image.

  Specifically, after a predetermined time has elapsed after the registration sensor detects the leading edge of the transfer paper, the rotational driving of the registration roller pair 19 and the photosensitive drum 27 is started, and the registration sensor detects the trailing edge of the transfer paper. After a predetermined time has elapsed, the rotational driving of the registration roller pair 19 and the photosensitive drum 27 is stopped. The registration sensor detects the sheet length along the transfer sheet conveyance direction of the transfer sheet sent from the sheet cassette 13 to the sheet conveyance path 18, and detects the trailing edge after detecting the leading edge of the transfer sheet. The length of the transfer paper (direction along the transfer paper conveyance direction) is detected based on the time until detection.

  The registration roller pair 19 is connected to a drive source (not shown) such as a motor. The registration roller pair 19 corrects the oblique feeding of the transfer paper by stopping the transfer paper instantaneously when the leading edge of the transfer paper is nipped in the stationary state.

(Configuration of the image forming unit 20)
In the present embodiment, the image forming unit 20 includes a replenishment toner storage container 28, a developing unit 29, and a transfer unit 30.

(Configuration of Replenishment Toner Storage Container 28)
The replenishment toner storage container 28 includes a container main body 31 that stores replenishment toner, and a container cover 32 that closes the upper surface opening of the container main body 31. Further, the replenishment toner storage container 28 includes a pair of toner stirring members 33 and 34 and a spiral rod 35 therein.

  The toner stirring members 33 and 34 are provided from one side surface (drive unit side) of the container body 31 to the other side surface. The toner agitating members 33 and 34 are provided with agitating blades 36 and convey the toner stored in the container body 31 to the spiral rod 35 while agitating the toner.

  The spiral rod 35 conveys the replenishment toner stirred and conveyed by the toner agitating members 33 and 34 toward one side in the transfer paper width direction, and supplies the replenishment toner to the developing unit 29 from the one side.

  The replenishment toner storage container 28 is detachable (replaceable) with respect to the apparatus main body 12, and the replenishment toner storage container 28 can be attached and detached by opening a front cover (not shown) of the apparatus main body 12. Exchange).

(Configuration of developing unit 29)
The developing unit 29 supplies toner to the photosensitive drum 27 as an image carrier while circulating and moving the toner inside the housing. A pair of spiral feeders (stirring mixers) 37, 38 and a developing roller 39 facing the photosensitive drum 27 are rotatably provided.

  In addition, a partition wall 40 is formed in the developing unit 29 to isolate the spiral feeders 37 and 38 from each other. A gap is formed between both ends of the partition wall 40 and vertical walls of the developing unit 29 (wall surfaces at both ends in the transfer paper width direction perpendicular to the paper surface), and the replenishment toner storage container 28 is formed on one side in the transfer paper width direction. After the toner is agitated and conveyed (forward path) to one side of the developing unit 29 (in the depth direction of the paper surface) by the spiral feeder 37 disposed below the spiral rod 35 including the toner replenished from A circulation path is formed in which the toner is stirred and conveyed (returned) by the spiral feeder 38 to the other side (front side of the paper) by the spiral feeder 38 and then folded again by the gap on the other side.

  Further, a toner sensor 41 that detects the toner amount of the developing unit 29 is provided on the outer wall surface of the developing unit 29.

  The developing roller 39 is disposed so that the peripheral surface thereof faces the peripheral surface of the photosensitive drum 27. Accordingly, the toner being conveyed to the developing roller 39 is supplied to the peripheral surface of the photoconductive drum 27 via the developing roller 39, whereby a toner image corresponding to the electrostatic latent image is formed on the peripheral surface of the photoconductive drum 27. It is formed.

  The toner sensor 41 detects the toner amount in the vicinity of the installation location (near the toner replenishing portion) based on the output signal, and the control circuit (not shown) supplies the toner replenishing amount from the replenishing toner storage container 28 and the replenishment timing. Is controlled.

(Configuration of transfer unit 30)
The transfer unit 30 includes a charging device 42 and an exposure device 43 in the order of the image forming process along the rotation direction of the photosensitive drum 27 (counterclockwise direction in FIG. 1) around the photosensitive drum 27 (for example, made of amorphous silicon). A developing roller 39, a transfer roller 44, a cleaning device 45, and a static elimination device 46 are provided.

  A charging bias obtained by superimposing an AC voltage (Vac) on a DC voltage (Vdc) is applied to the charging device 42.

  The exposure device 43 processes image data included in print data transmitted from a personal computer (not shown), for example, and irradiates the surface of the photosensitive drum 27 with laser light. In addition to the above-described image data, the print data here includes, for example, data relating to various settings such as the number of image forming processing copies, enlargement / reduction ratio, and image density.

  A transfer voltage is applied to the transfer roller 44, and the toner image formed on the surface of the photosensitive drum 27 is transferred by the applied voltage while the transfer paper is nipped and conveyed in cooperation with the photosensitive drum 27.

  The cleaning device 45 removes transfer residual toner, transfer paper powder, and the like remaining on the surface of the photosensitive drum 27 after toner transfer to the transfer paper.

  For example, an LED light source or the like is used as the charge removal device 46, and the photosensitive drum 27 charged by the charging device 42 is discharged.

(Configuration of the fixing unit 21)
In order to fix the unfixed toner image transferred to the surface of the transfer paper by the image forming unit 20, the fixing unit 21 is heated as a heating member disposed on the surface of the transfer paper, that is, on the unfixed toner image side. A roller 47 (or a heating belt) and a pressure roller 48 as a pressure member facing the heating roller 47 across the paper feed conveyance path 18 are provided, and the pressure roller 48 is brought into pressure contact with the heating roller 47. Transfer the transfer paper to the nip.

  The unfixed toner image formed on the surface of the transfer paper is melted by directly contacting the heating roller 47, and is melted on the surface of the transfer paper as it is by being pressed by the pressure roller 48 from the back surface side of the transfer paper. The toner is fixed as a fixed image.

  The surface of the heating roller 47 is subjected to a surface coating process so that the molten toner does not adhere. Further, the molten toner or the like adhering to the surface of the heating roller 47 is removed by a cleaning device (not shown) or the like.

(Configuration of each paper feed path)
The paper feeding / conveying path 18 is used to transfer the uppermost transfer paper taken out from the paper feeding cassette 13 by the cassette paper feeding unit between the registration roller pair 19, the photosensitive drum 27 and the transfer roller 44 (transfer unit 30), and the fixing unit 21. After the nip conveyance in order, a path from the discharge unit 22 to the discharge tray 17 is formed.

  The tray sheet feeding path 23 forms a path for conveying the uppermost transfer sheet taken out from the sheet feeding tray by the tray sheet feeding unit toward the registration roller pair 19.

  The branch path 24 includes a switching member 49 provided to be switchable downstream in the transport direction from the fixing unit 21 of the paper feed transport path 18, and transfer paper is transferred to the switchback path 25 by switching the path of the switch member 49. It forms a route for transportation.

  The switchback path 25 includes a switchback roller pair 50 that is provided above the discharge unit 22 and rotates in the forward and reverse directions. The path to be formed.

  The reverse path 26 is formed by the cooperation of the apparatus main body 12 and the side panel 51, and forms a path for transporting the transfer paper transported from the switchback path 25 toward the registration roller pair 19.

(Configuration of side panel 51)
As shown in FIG. 2, the side panel 51 that forms a part of one outer wall surface of the multifunction machine 11 is formed below the outer wall surface side to support the paper feed tray in a rotatable manner and always (not used). ), A recess 52 for storing the manual feed tray 14, an opening / closing operation handle 53 rotatably provided on the outer wall surface side, and a lower back side located in the apparatus main body 12. A transfer conveyance unit 54. Further, as shown in FIG. 3, the side panel 51 and the transfer / conveying unit 54 rotate around the same unit support shaft 55 provided below the apparatus main body 12, and as shown in FIGS. In addition, the degree of opening differs depending on the length of the cover strap 56 and one of the unit straps 57 fixed at one end to the apparatus main body 12, and this is in combination with the lower unit support shaft 55 as a rotation fulcrum. Thus, the opening state can be expanded upward, and the transfer roller 44 replacement work and the ease of JAM processing are ensured. Further, the side panel 51 is always (closed) at the back side thereof, the transfer conveyance unit 54 is defined so as to define the distance between the back surface of the transfer conveyance unit 54 facing the back surface side, that is, the interval in the transfer paper thickness direction of the reverse path 26. Support. At this time, the transfer conveyance unit 54 is released from the support state by the side panel 51 in conjunction with the opening operation of the side panel 51 using the opening / closing operation handle 53, and the transfer roller 44 is separated from the photosensitive drum 27. It is configured as follows.

  As shown in FIGS. 6 to 8, the opening / closing operation handle 53 is rotatably supported by a panel support shaft 58 provided at the upper part on the back side of the side panel 51, so that the opening / closing operation handle 53 can be rotated. In conjunction with this, cover fixing hooks 59 which are provided at both ends of the panel support shaft 58 and engage with cover fixing portions (not shown) of the apparatus main body 12 are rotated. Further, on the back surface side of the side panel 51, the connecting slider 60 that slides up and down in conjunction with the rotation of the cover fixing hook 59 and the lower end of the connecting slider 60 can be rotated. A unit fixing hook 61 is provided. The unit fixing hook 61 is rotated by the downward displacement of the connecting slider 60, and the support state of the transfer conveyance unit 54 by the side panel 51 is released.

  The unit fixing hook 61 is engaged with a unit fixing hook engaging portion 62 provided on the apparatus main body 12 side so as to position the entire transfer / conveyance unit 54, and the relative relationship between the side panel 51 and the transfer / conveyance unit 54. A hook portion 63 for defining the position and a separation operation portion 64 for separating the transfer roller 44 from the photosensitive drum 27 in conjunction with the opening operation of the opening / closing operation handle 53 are provided. The unit fixing hook 61 is biased (torsion spring or the like) in a direction in which the hook portion 63 engages with the unit fixing hook engaging portion 62.

(Configuration of transfer conveyance unit 54)
As shown in FIGS. 9 to 12, the transfer conveyance unit 54 includes a unit base housing 66 in which a unit base bracket 65 through which the unit support shaft 55 passes is fixed below both ends, and a transfer roller unit provided in the unit base housing 66. And a transfer roller unit 68 held by a holding portion 67.

  The unit base housing 66 directly holds one of the registration rollers 69 positioned on the side panel 51 side in a rotatable manner. The unit base housing 66 includes a registration roller pressing spring member 71 that biases one registration roller 69 toward the other registration roller 70 inside the apparatus main body 12. The front surface side, the back surface side, and the bottom surface side of the unit base housing 66 form a part of the above-described transport paths 18 and 26.

  As shown in FIG. 13, the transfer roller unit 68 includes a transfer roller housing 72 housed in a transfer roller unit holding portion 67, a transfer roller 44, and a transfer roller that urges the transfer roller 44 toward the photosensitive drum 27. A pressing spring member 73, a pre-transfer back side guide 74 that is one of the pair of pre-transfer guides (side panel 51 side) that forms the transport path 18 between the registration roller pair 19 and the transfer unit 30, and a photosensitive drum. 27, the separation needle 75 that separates the transfer paper from the unit 27, and the separation operation portion 64 of the unit fixing hook 61, and the transfer roller pressing spring member 73 is expanded and contracted against the bias, thereby moving the transfer roller 44 to the photosensitive drum. And a transfer roller lock release lever 76 (see FIG. 8) that is spaced apart from 27.

  Therefore, when the side panel 51 is opened, the transfer roller 44 does not contact the photosensitive drum 27 more than necessary at the start of the opening operation, and damage to the photosensitive drum 27 is suppressed.

  A plurality of separation needles 75 are arranged along the transfer paper width direction so that the leading end is exposed to the sheet feeding conveyance path 18 downstream of the transfer roller 44 in the sheet conveyance direction. The transfer paper charged by the transfer roller 44 is discharged by discharging between the separation needle 75 and the transfer paper is separated from the photosensitive drum 27.

(Configuration of the apparatus body 12)
As shown in FIG. 14, the apparatus main body 12 includes a photosensitive drum 27, the other registration roller 70, and a unit fixing resin member 77.

  The unit fixing resin member 77 includes a unit strap guide groove 78 that engages with the unit strap 57, a unit fixing hook engaging portion 62, a transfer, A transfer roller positioning portion 80 having a substantially U-shaped groove for positioning the transfer roller 44 by engaging with transfer roller collars 79 provided at both ends of the roller 44, and a registration roller provided at both ends of one registration roller 69 A substantially U-shaped registration roller positioning portion 82 for positioning one registration roller 69 by engaging with the collar 81, and a front-transfer front-side guide as the other pre-transfer guide facing the pre-transfer back-side guide 74. 83.

(Example)
Next, specific examples of the image forming apparatus according to the present invention will be described with reference to FIGS.

  The positioning of the transfer roller 44, one registration roller 69, and the pre-transfer back side guide 74 disposed in the transfer / conveyance unit 54 is arranged in the apparatus main body 12 because the accumulated tolerance increases if determined by the transfer / conveyance unit 54. The pair of unit fixing resin members 77 are positioned.

  The unit fixing resin members 77 are positioned at both ends of the transfer paper width direction, and are basically configured to have the same function although their shapes are different. Accordingly, in the following description, the same reference numerals are used for the description.

  Each unit fixing resin member 77 has a unit strap guide groove 78, a transfer roller positioning unit 80, a registration roller positioning unit 82, and a front surface side that positions and supports both ends of the pre-transfer surface side guide 83 that is the apparatus main body side. A guide support portion 84 and a guide abutting surface 85 against which opposing surfaces (transfer paper conveyance path surfaces) in the vicinity of both ends of the pre-transfer rear surface side guide 74 facing the pre-transfer front surface side guide 83 when the side panel 51 is closed, It is equipped with.

  The transfer roller positioning portion 80 is formed in a groove shape that opens toward the center of the photosensitive drum 27, and the transfer roller collar 79 is fitted to the groove, so that the circumferential position of the photosensitive drum 27, that is, The vertical direction, which is the transfer paper conveyance direction, and the transfer paper width direction are positioned (aligned). A constant nip pressure is secured in the center direction of the photosensitive drum 27 by the transfer roller pressing spring member 73.

  The registration roller positioning portion 82 is formed in a groove shape that opens toward the center of the other registration roller 70 disposed on the inner side of the apparatus main body 12 of the registration roller pair 19, and is formed on the inner surface of the side panel 51. The registration roller collar 81 of one registration roller 69 arranged on the side is fitted to position (align) the vertical direction, which is the transfer sheet conveyance direction, of the registration roller 69 and the transfer sheet width direction. In the center direction of the other registration roller 70, a constant nip pressure is secured by the registration roller pressing spring member 71.

  The pre-transfer surface side guide 83 is positioned by fitting the pre-transfer surface side guide 83 to the slit-shaped surface side guide support portion 84. At this time, U grooves 83a that are open to the end surfaces are formed at both ends of the pre-transfer surface side guide 83, and positioning is performed by fitting the fixing ribs 84a of the surface side guide support portion 84 into the U grooves 83a. .

  Further, the pre-transfer rear surface side guide 74 rotates about a guide rotation fulcrum 86 provided in the transfer conveyance unit 54 and abuts against the guide contact surface 85 by a spring bias, whereby the pre-transfer front surface side guide 83. Is defined.

DESCRIPTION OF SYMBOLS 11 ... Multifunctional machine 12 ... Apparatus body 19 ... Registration roller pair 27 ... Photosensitive drum 44 ... Transfer roller 51 ... Side panel 53 ... Opening / closing operation handle 54 ... Transfer conveyance unit 69 ... One registration roller 70 ... Other registration roller 74 ... Back-side guide before transfer 77 ... Resin member for fixing unit 80 ... Transfer roller positioning part 82 ... Registration roller positioning part 83 ... Pre-transfer front side guide 83a ... U-groove 84 ... Front side guide support part 85 ... Guide contact surface 86 ... Guide rotation fulcrum

Claims (2)

A transfer unit that is disposed in the middle of the conveyance path for conveying the transfer paper taken out from the paper supply unit upward in the vertical direction of the main body of the apparatus, and includes an image carrier and a transfer roller. In an image forming apparatus comprising: a pair of registration roller pairs disposed; and a transfer conveyance unit that is provided along a side surface of the apparatus main body and opens a part of the transfer unit from the pair of registration rollers.
The transfer conveyance unit is arranged with the transfer roller and one of the registration roller pair, and guides the front and back of the transfer paper so as to form a conveyance path between the registration roller pair and the transfer unit. A separation mechanism that separates one of the pair of pre-transfer guides, the one registration roller and the transfer roller from the other of the pair of registration rollers and the image carrier in conjunction with an opening operation of the transfer conveyance unit; And a single positioning member for positioning at least each transfer paper conveyance direction and transfer paper width direction of the one registration roller, the transfer roller, and the other of the pre-transfer guides in the apparatus main body. The positioning member is made of resin, and engages with both end portions of the one registration roller to position the transfer paper conveyance direction and the transfer paper width direction. Engage with the roller positioning unit, the transfer roller positioning unit that engages with both ends of the transfer roller to position the transfer paper conveyance direction and the transfer paper width direction, and the other end of the pre-transfer guide. a guide positioning part for positioning the paper conveying direction and transfer the paper width direction, the transfer sheet conveyance road of the one pre-transfer guide defines the opposing distance of the respective guide abuts the guide abutment surface and the Bei strong point An image forming apparatus. The registration roller positioning portion and the transfer roller positioning portion are biased by a biasing member that biases the one registration roller and the transfer roller independently toward the other registration roller and the image carrier. And the separation mechanism unit separates the one registration roller and the transfer roller from the other registration roller and the image carrier against the urging of the urging member. The image forming apparatus according to claim 1.

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