JP3907597B2 - Image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electrophotographic or electrostatic recording image forming apparatus such as a copying machine or a printer.
[0002]
[Prior art]
In conventional image forming apparatuses such as copiers, printers, and facsimile machines, in order to reduce the size of the entire apparatus, for example, a toner image formed on an image carrier using an electrophotographic system is transferred to an intermediate transfer member, There is known a color image forming apparatus that employs a method of transferring a toner image transferred to an intermediate transfer member onto a transfer material.
[0003]
In general, a belt is used as an intermediate transfer member, and a toner image formed by an image carrier is primarily transferred to a rotating intermediate transfer belt, and a color image is formed by repeatedly transferring the toner image for a predetermined color. . Then, the intermediate transfer belt is conveyed by conveying a transfer material to a secondary transfer portion formed at a nip portion between the intermediate transfer belt and the secondary transfer roller in synchronization with the image formation, and applying a bias to the secondary transfer roller. The above color image is transferred to a transfer material to obtain a color image.
[0004]
Here, in the intermediate transfer type image forming apparatus, when the transfer material is jammed (paper jam) in the secondary transfer unit, or in order to replace the secondary transfer roller, the secondary transfer roller is installed. It is configured to be able to be separated from the intermediate transfer belt. For example, as shown in FIG. 7, in an intermediate transfer type image forming apparatus that forms a secondary transfer portion by nipping an intermediate transfer belt 200 and a secondary transfer roller 201, the secondary transfer roller 201 is a roller holding member. The roller holding member 202 is attached so as to be rotatable about the swing shaft 203. The roller holding member 202 is provided with a hook 205 that can rotate around the support shaft 204. When the hook 205 is locked to a locking shaft 206 provided on the apparatus main body side, the intermediate transfer belt 200 and the secondary transfer roller 201 to form a nip.
[0005]
In the above configuration, when the hook 205 is removed from the locking shaft 206 in the case of jam processing or the like, the roller holding member 202 can rotate about the swing shaft 203 in the counterclockwise direction of FIG. Then, the secondary transfer roller 201 is separated from the intermediate transfer belt 200, and jamming or the like can be easily performed.
[0006]
[Patent Document 1]
Japanese Patent Laid-Open No. 2001-117465
[Problems to be solved by the invention]
However, in the conventional example, as can be seen from FIG. 7, the axis connecting the locking shaft 206 and the hook support shaft 204 does not coincide with the pressing direction of the secondary transfer roller 201.
[0008]
Therefore, the roller holding member 202 receives a rotational moment around the hook support shaft 204 by the reaction force of the contact pressure of the secondary transfer roller 201 (arrow M in the figure). As a result, since the roller holding member 202 is supported by the apparatus main body by the swing shaft 203, the housing of the roller holding member 202 is deformed. In other words, since the roller holding member 202 is not a perfect rigid body, the applied pressure cannot be obtained as originally designed, and the contact position of the secondary transfer roller 201 and the roller holding member 202 are formed and conveyed. Since the positional accuracy of the guide portion 207 or the like for guiding the transfer material to be transferred is deteriorated, there is a possibility that a transfer defect image is generated.
[0009]
The present invention has been made in view of the above problems, and an object of the present invention is to provide an image forming apparatus capable of positioning a transfer transport unit with high accuracy without depending on the rigidity of the transfer transport unit.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, a typical configuration according to the present invention includes an intermediate transfer belt carrying a toner image, an intermediate transfer belt unit having the intermediate transfer belt, and a toner image on the intermediate transfer belt as a transfer material. A secondary transfer unit for transferring the toner image to the recording medium, a secondary transfer unit having the secondary transfer unit, and a transfer conveyance unit for holding the secondary transfer unit. The transfer conveyance unit has a support unit. Then, by engaging the support means with the intermediate transfer belt unit, the transfer conveyance unit is supported by the intermediate transfer belt unit, and the intermediate transfer belt and the secondary transfer means are in contact with each other, and the support means By disengaging the intermediate transfer belt unit from the intermediate transfer belt unit. In the image forming apparatus in which the secondary transfer unit is separated from the,
The secondary transfer unit can be pulled out from the transfer conveyance unit, and when the support means is engaged with the intermediate transfer belt unit, the support means has a path through which the secondary transfer unit can be pulled out. intercepting, wherein when the support means is released from the intermediate transfer belt unit, the supporting means is characterized by deviating from the path that may draw the secondary transfer unit.
[0011]
As another configuration, the supporting unit is provided in the intermediate transfer belt unit. As another configuration, when the support means is engaged with the intermediate transfer belt unit, the secondary transfer unit cannot be pulled out from the transfer conveyance unit, and the support means is not attached to the intermediate transfer belt. The secondary transfer unit is configured to be able to be pulled out from the transfer conveyance unit when the engagement with the unit is released .
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of an image forming apparatus to which the present invention is applied will be described in detail with reference to the drawings.
[0013]
FIG. 1 is a diagram showing a schematic configuration of a four-drum full-color image forming apparatus using an intermediate transfer belt, which is an example of an image forming apparatus according to an embodiment of the present invention.
[0014]
{Overall configuration of image forming apparatus}
In FIG. 1, 1 is a 4-drum full-color image forming apparatus, 2 is a 4-drum full-color image forming apparatus main body (hereinafter referred to as “apparatus main body”), and P (PY, PM, PC, PBk) is detachable from the apparatus main body 2. Provided are four color process cartridges of yellow (Y), magenta (M), cyan (C), and black (Bk), 31 an intermediate transfer body unit having an intermediate transfer belt 30 as an intermediate transfer body, and 25 a fixing. It is a vessel.
[0015]
Here, the process cartridge P is disposed on the outer peripheral surface of the photosensitive drum 26 (26Y, 26M, 26C, 26Bk), which is an image carrier, and the photosensitive drum 26, respectively. The electrostatic latent images of the respective colors on the surface of the photosensitive drum formed by exposure by the primary charger 50 and the laser exposure device 28 (28Y, 28M, 28C, 28Bk) are converted into yellow, magenta, A developing unit 51 that develops using cyan and black toners is provided, and is arranged in parallel along the intermediate transfer belt 30.
[0016]
Further, a primary transfer roller 52 that forms a primary transfer portion together with the photosensitive drum 26 is disposed opposite to the position where the intermediate transfer belt 30 is sandwiched with the photosensitive drum 26.
[0017]
On the other hand, the intermediate transfer belt unit 31 as an intermediate transfer unit includes an intermediate transfer belt 30 and three rollers, a driving roller 100 that stretches the intermediate transfer belt 30, a tension roller 105, and a secondary transfer counter roller 108. Yes.
[0018]
Reference numeral 27 denotes a secondary transfer roller disposed at a position sandwiching the intermediate transfer belt 30 of the secondary transfer counter roller 108, and 33 denotes a transfer conveyance unit that holds the secondary transfer roller 27.
[0019]
Reference numeral 3 denotes a feeding unit that feeds the transfer material S to the secondary transfer unit configured by a contact portion between the secondary transfer roller 27 and the secondary transfer counter roller 108 with the intermediate transfer belt 30 interposed therebetween. The feeding unit 3 holds a cassette 20 containing a plurality of transfer materials S, a feeding roller 21, a conveying roller 23, a double feed prevention retard roller pair 22, and a registration unit 32 (registration roller pair 24). ) Etc.
[0020]
The intermediate transfer belt unit 31 is detachably provided on the apparatus main body 2. When the intermediate transfer belt unit 31 is taken out, the unit replacement door 206 attached to the side wall surface of the apparatus main body 2 is opened and then pulled out in the arrow a direction. ing. At this time, the transfer conveyance unit 33 and the registration unit 32 are configured to be retracted to positions not shown so that the intermediate transfer belt unit 31 can be pulled out. Further, the unit replacement door 206 is used not only for opening and closing the intermediate transfer belt unit but also for removing jammed paper outside the apparatus.
[0021]
{Image forming operation}
Next, an image forming operation of the four-drum full-color image forming apparatus 1 configured as described above will be described.
[0022]
When the image forming operation is started, first, the transfer material S in the cassette 20 is fed by the feed roller 21 and then separated one by one by the retard roller pair 22 and then passed through the transport roller 23 and the like. It is conveyed to the roller pair 24. At this time, the registration roller pair 24 stops rotating, and the transfer material S is abutted against the nip of the registration roller pair 24, whereby the skew of the transfer material S is corrected.
[0023]
On the other hand, in parallel with the transfer operation of the transfer material S, for example, in the yellow process cartridge PY, the surface of the photosensitive drum 26Y is first uniformly negatively charged by the primary charger 50, and then the image is output by the laser exposure device 28Y. By performing the exposure, an electrostatic latent image corresponding to the yellow image component of the original is formed on the surface of the photosensitive drum 26Y.
[0024]
Next, the electrostatic latent image is developed with a negatively charged yellow toner by the developing device 51 and visualized as a yellow toner image. The yellow toner image thus obtained is primarily transferred onto the intermediate transfer belt 30 by the primary transfer roller 52. After the toner image is transferred, the transfer residual toner adhering to the surface of the photosensitive drum 26Y is removed by the cleaner 53 and used for the next image formation.
[0025]
Then, such a toner image forming operation is performed at a predetermined timing in the other process cartridges P, and each color toner image formed on each photosensitive drum 26 is transferred onto the intermediate transfer belt 30 by each primary transfer unit. Are transferred to the primary transfer.
[0026]
Next, the four-color toner images transferred onto the intermediate transfer belt 30 in this way are moved to the secondary transfer portion as the intermediate transfer belt 30 rotates in the arrow direction. Further, the transfer material S whose skew has been corrected by the registration roller pair 24 is sent to the secondary transfer portion in time with the image on the intermediate transfer belt 30.
[0027]
Thereafter, the four-color toner images on the intermediate transfer belt 30 are secondarily transferred onto the transfer material S by the secondary transfer roller 27 in contact with the intermediate transfer belt 30 with the transfer material S interposed therebetween. Then, the transfer material S onto which the toner image has been transferred in this way passes through the post-transfer conveyance unit 34 and is conveyed to the fixing device 25 to fix the toner image, and then the lower discharge roller pair 29a and the upper discharge roller pair. By 29b, it is discharged and stacked on the upper surface of the apparatus main body. The intermediate transfer belt 30 that has finished the secondary transfer has the transfer residual toner remaining on the surface removed by a belt cleaner (not shown).
[0028]
{Configuration around the secondary transfer section}
Here, the configuration around the secondary transfer portion will be described in detail with reference to FIG.
[0029]
As shown in FIG. 2, a registration unit 32 is configured by the registration roller pair 24, the pre-registration sensor flag 41, and the photo interrupter 40. The pre-registration sensor flag 41 is urged clockwise in the figure by a spring (not shown), and can move to a position where the photo interrupter 40 is blocked when the transfer material S is present immediately before the registration roller pair 24 (FIG. Falls in the direction of the middle arrow). Therefore, it is possible to detect the presence or absence of the transfer material S and the timing at which the front and rear ends of the transfer material S pass.
[0030]
Similarly, the post-transfer conveyance unit 34 is also provided with a post-transfer sensor flag 43 and a photo interrupter 40 that are urged clockwise in the drawing by a spring (not shown), and the transfer material S after the secondary transfer is provided. It can be detected that the toner is conveyed to the fixing device at a predetermined timing without sticking to the intermediate transfer belt 30.
[0031]
{Transfer transport unit}
Next, the transfer conveyance unit 33 will be described.
[0032]
As shown in FIG. 2, the transfer conveyance unit 33 as a transfer conveyance means includes a secondary transfer roller unit 61 as a secondary transfer roller holding means, and a pre-transfer lower guide 45 (transfer provided in the intermediate transfer belt unit 31). The front upper guide 44 constitutes a pre-transfer conveyance path), and is configured to be swingable about a transfer conveyance unit swinging shaft 46.
[0033]
In FIG. 2, reference numeral 49 denotes a static elimination needle for neutralizing the sheet after the secondary transfer.
[0034]
The state of FIG. 2 shows a state in which the transfer conveyance unit 33 is held by the intermediate transfer belt unit 31 by the unit support hook 19 provided in the transfer conveyance unit 33, and is a unit that is a support means for the transfer conveyance unit 33. The support hook 19 is positioned with respect to the secondary transfer counter roller shaft 17 which is the rotation shaft of the secondary transfer counter roller 108 which is the belt conveying means provided in the intermediate transfer belt unit 31. Therefore, since the positioning can be performed directly on the rotation shaft of the secondary transfer counter roller 108, the positioning accuracy of the transfer conveyance unit 33 is improved.
[0035]
The unit support hook 19 is similarly provided on the opposite side with the intermediate transfer belt unit 31 in between, and two unit support hooks are provided by a hook support shaft 16 provided with a D cut as a positioning shaft of the hook 19. It is comprised so that 19 may rotate integrally.
[0036]
The secondary transfer roller unit 61, which is a secondary transfer unit, has a secondary transfer roller 27, and these constitute secondary transfer means. The secondary transfer roller unit 61 holds the secondary transfer roller 27 in a state where the secondary transfer roller 27 is pressed in the direction of the intermediate transfer belt 30 by the bias of the roller pressure spring 47.
[0037]
Further, in the present embodiment, the rotation shaft 27a of the secondary transfer roller 27 and the secondary transfer counter roller shaft 17 are configured in parallel, and the axis of the hook support shaft 16 exists on a plane formed by both axes. The pressing direction of the secondary transfer roller 27 is also parallel to this plane.
[0038]
On the other hand, the secondary transfer roller unit 61 holds the secondary transfer roller 27, and holds the secondary transfer roller 27 in a state of being pressed in the direction of the intermediate transfer belt with a configuration described later.
[0039]
Further, the secondary transfer roller unit 61 is configured to be attachable to and detachable from the transfer conveyance unit 33, and is configured to be drawn out in the front direction (direction perpendicular to the paper surface) in FIG. Note that if the secondary transfer roller unit 61 is pulled out of the transfer conveyance unit 33 with the transfer conveyance unit 33 mounted, the surfaces of the intermediate transfer belt 30 and the secondary transfer roller 27 are damaged. However, in this embodiment, as shown in FIG. 2, the unit support hook 19 overlaps the secondary transfer roller unit 61 when the transfer conveyance unit 33 is mounted, and therefore the secondary transfer roller unit 61 is pulled out. I can't do that.
[0040]
Next, a state in which the transfer conveyance unit 33 is moved from the intermediate transfer belt unit 31 to the release position will be described with reference to FIG.
[0041]
2, when the unit support hook 19 is released from the secondary transfer counter roller shaft 17 (withdrawn in the clockwise direction), the transfer conveyance unit 33 swings around the transfer conveyance unit swing shaft 46 by its own weight. Then, the state shown in FIG. 3 is obtained. At this time, since the unit support hook 19 is urged clockwise by a torsion coil spring (not shown), the state shown in FIG. 3 is obtained. However, the load of the torsion coil spring is set so as not to hinder the positioning of the unit support hook 19 on the secondary transfer counter roller shaft 17 in the state of FIG.
[0042]
In the state of FIG. 3, since the unit support hook 19 does not overlap the secondary transfer roller unit 61, the secondary transfer roller unit 61 can be pulled out from the transfer conveyance unit 33.
[0043]
FIG. 4 shows a configuration around the secondary transfer portion in a state where the secondary transfer roller unit 61 is pulled out from the transfer conveyance unit 33.
[0044]
FIG. 5 shows a perspective view of the secondary transfer roller unit 61 pulled out from the transfer conveyance unit 33, and FIGS. 6A and 6B show a front view and a sectional view thereof.
[0045]
As shown in FIGS. 5 and 6, the secondary transfer roller unit 61 includes a secondary transfer roller 27, a secondary transfer roller bearing 48 that supports the secondary transfer roller 27, a roller pressure spring 47, and a roller gear 63. By replacing the entire secondary transfer roller unit 61, the user can replace the secondary transfer roller 27, which is a consumable item, without getting his hands dirty.
[0046]
As shown in FIG. 4, the secondary transfer roller unit 61 mounting portion of the transfer conveyance unit 33 performs positioning when the secondary transfer roller unit 61 is mounted and guides when the secondary transfer roller unit 61 is mounted. Therefore, the user can attach the secondary transfer roller unit 61 only by pushing it in.
[0047]
Here, if the user tries to set the transfer / conveyance unit 33 to the intermediate transfer belt unit 31 without pushing the secondary transfer roller unit 61 to the end, as shown in FIG. The unit support hook 19 cannot be hung on the secondary transfer counter roller shaft 17 by interfering with the roller unit 61. Therefore, the user notices a mounting failure of the secondary transfer roller unit 61.
[0048]
In the state of FIG. 2 in which the transfer conveyance unit 33 is set on the intermediate transfer belt unit 31, the roller gear 63 installed on the transfer roller 27 shown in FIG. 5 and the drive rotatably supported on the transfer conveyance unit 33 side. The gear 64 meshes. Here, both the roller gear 63 and the driving gear 64 are helical gears, and when the driving force is transmitted from the driving gear 64 and the secondary transfer roller 27 rotates in the direction shown in the figure, the driving load (the shaft of the secondary transfer roller 27 and the secondary transfer roller 27). 5 in the direction of arrow B in FIG. 5 depending on the sliding frictional force with the bearing 47 and the reaction force generated by the peripheral speed difference set to “the peripheral speed of the intermediate transfer belt 30” ≦ “the peripheral speed of the secondary transfer roller 27”. Thrust is generated. Therefore, as can be seen from FIG. 2, the secondary transfer roller unit 61 is positioned by being urged and abutted against the unit support hook 19 side. In the state of FIG. 2, the grip 62 gripped by the user when attaching / detaching the secondary transfer roller unit 61 shown in FIG. 5 is provided with relief on the unit support hook 19 side so as not to interfere with the unit support hook 19. .
[0049]
As described above, the rotation shaft of the secondary transfer roller 27 and the secondary transfer counter roller shaft 17 are configured in parallel, and the axis of the hook support shaft 16 exists on a plane formed by both the shafts. Further, since the pressing direction of the secondary transfer roller is configured in parallel to this plane, the hook support shaft 16 around the hook support shaft 16 generated by the contact reaction force of the secondary transfer roller 27, which has been a problem in the conventional example, is formed. The rotational moment M does not act on the transfer conveyance unit 33. Accordingly, deformation of the transfer / conveying unit 33 is prevented, so that an applied pressure as originally designed can be obtained, and the contact position of the secondary transfer roller 27, the position of the pre-transfer lower guide 45, and the position of the charge removal needle 49 Positioning with high accuracy is possible.
[0050]
In addition, since the rigidity of the transfer / conveyance unit 33 itself can be lowered as compared with the conventional example, the cost can be reduced by reducing the unit weight, and the operability can be improved by reducing the operation force of the user.
[0051]
Further, in the state where the transfer conveyance unit 33 is set on the intermediate transfer belt unit 31 (FIG. 2), the unit support hook 19 covers the handle 62 of the secondary transfer roller unit 61 shown in FIG. The replacement of the next transfer roller unit is configured so that the user can be aware that the transfer and transport unit 33 is performed in the state shown in FIG.
[0052]
In the present embodiment, the case where the unit support hook 19 as the support means is installed in the transfer conveyance unit 33 as the transfer conveyance means has been taken up, but the present invention is not limited to this, The same effect can be obtained even if the unit support hook 19 is installed on the intermediate transfer belt unit 31 side as an intermediate transfer means.
[0053]
Further, in the present embodiment, the image forming apparatus using the intermediate transfer belt as the intermediate transfer unit has been described in detail. However, even in the configuration using the intermediate transfer drum, the unit support hook 19 is located at the rotational axis center of the intermediate transfer drum. The same effect can be obtained by configuring so as to be positioned.
[0054]
[0055]
[0056]
[0057]
[0058]
【The invention's effect】
As described above, according to the present invention, it is possible to easily replace the secondary transfer roller unit, and it is possible to prevent poor mounting and the like.
[0059]
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a schematic configuration of a four-drum full-color image forming apparatus using an intermediate transfer belt, which is an example of an image forming apparatus.
FIG. 2 is a diagram illustrating a configuration around a transfer conveyance unit of a four-drum full-color image forming apparatus using an intermediate transfer belt (a state where the transfer conveyance unit is suspended from the intermediate transfer belt unit).
FIG. 3 is a diagram illustrating a configuration around a transfer conveyance unit of a four-drum full-color image forming apparatus using an intermediate transfer belt (a state where the transfer conveyance unit is retracted from the intermediate transfer belt unit).
FIG. 4 is a diagram illustrating a configuration around a transfer conveyance unit of a four-drum full-color image forming apparatus using an intermediate transfer belt (a state where a secondary transfer roller unit is removed from the transfer conveyance unit).
FIG. 5 is a perspective view of a secondary transfer roller unit.
6A is a front view of the secondary transfer roller unit, and FIG. 6B is a cross-sectional view of the secondary transfer roller unit.
FIG. 7 is a diagram illustrating a configuration around a transfer conveyance unit of a conventional color image forming apparatus.
[Explanation of symbols]
PY, PM, PC, PBk... Process cartridge S... Transfer material 1... Image forming apparatus 2... Apparatus body 3... Feeder 16 ... Hook support shaft 17 ... Secondary transfer counter roller shaft 19 ... Unit support hook 20. ... feed roller 22 ... retard roller pair 23 ... conveying roller 24 ... registration roller pair 25 ... fixing devices 26Y, 26M, 26C, 26Bk ... photosensitive drum 27 ... secondary transfer roller 27a ... rotary shafts 28Y, 28M, 28C, 28Bk ... laser exposure device 29a ... lower discharge roller pair 29b ... upper discharge roller pair 30 ... intermediate transfer belt 31 ... intermediate transfer belt unit 32 ... registration unit 33 ... transfer transfer unit 34 ... post-transfer transfer unit 40 ... photo interrupter 41 ... before registration Sensor flag 43 ... Post-transfer sensor flag 44 ... Upper guide 45 before transfer Lower transfer guide 46 ... Transfer conveyance unit swing shaft 47 ... Roller pressure spring 48 ... Secondary transfer roller bearing 49 ... Static elimination needle 50 ... Primary charger 51 ... Developer 52 ... Primary transfer roller 60 ... Swing cam 61 ... Secondary transfer roller unit 62 ... handle portion 63 ... roller gear 64 ... drive gear 100 ... drive roller 105 ... tension roller 108 ... secondary transfer counter roller 206 ... unit replacement door

Claims (7)

An intermediate transfer belt carrying a toner image; an intermediate transfer belt unit having the intermediate transfer belt; a secondary transfer means for transferring the toner image on the intermediate transfer belt to a transfer material; and the secondary transfer means. A secondary transfer unit, and a transfer conveyance unit that holds the secondary transfer unit. The transfer conveyance unit includes a support unit, and the support unit is engaged with the intermediate transfer belt unit. The transfer conveyance unit is supported by the intermediate transfer belt unit, the intermediate transfer belt and the secondary transfer unit are in contact with each other, and the engagement of the support unit with the intermediate transfer belt unit is released. In the image forming apparatus in which the transfer conveyance unit is separated from the intermediate transfer belt unit and the intermediate transfer belt and the secondary transfer unit are separated from each other.
The secondary transfer unit can be pulled out from the transfer conveyance unit, and when the support means is engaged with the intermediate transfer belt unit, the support means has a path through which the secondary transfer unit can be pulled out. The image forming apparatus according to claim 1 , wherein when the support means is released from the intermediate transfer belt unit , the support means is out of a path through which the secondary transfer unit can be pulled out .   When the support means is engaged with the intermediate transfer belt unit, the secondary transfer unit cannot be pulled out from the transfer conveyance unit, and the support means releases the engagement with the intermediate transfer belt unit. 2. The image forming apparatus according to claim 1, wherein the secondary transfer unit can be pulled out of the transfer conveyance unit during the operation. An intermediate transfer belt carrying a toner image; an intermediate transfer belt unit having the intermediate transfer belt; a secondary transfer means for transferring the toner image on the intermediate transfer belt to a transfer material; and the secondary transfer means. A secondary transfer unit, and a transfer conveyance unit that holds the secondary transfer unit. The intermediate transfer belt unit includes a support unit, and the support unit is engaged with the transfer conveyance unit. The transfer conveyance unit is supported by the intermediate transfer belt unit, and the intermediate transfer belt and the secondary transfer unit come into contact with each other, and the engagement of the support unit with the transfer conveyance unit is released. In the image forming apparatus in which the conveyance unit is separated from the intermediate transfer belt unit and the intermediate transfer belt and the secondary transfer unit are separated from each other.
The secondary transfer unit can be pulled out from the transfer transport unit, and when the support means is engaged with the transfer transport unit , the support means blocks a path through which the secondary transfer unit can be pulled out. , wherein when the supporting means is released from the intermediate transfer belt unit, the pre-Symbol support means image forming apparatus characterized by deviating from the path that may draw the secondary transfer unit.   When the support means is engaged with the transfer conveyance unit, the secondary transfer unit cannot be pulled out from the transfer conveyance unit, and the support means releases the engagement with the transfer conveyance unit. 4. The image forming apparatus according to claim 3, wherein the secondary transfer unit can be pulled out from the transfer conveyance unit when the printer is in operation.   5. A tension roller that stretches the intermediate transfer belt, and the secondary transfer unit can be pulled out in a direction parallel to a rotation axis of the tension roller. The image forming apparatus according to any one of the above.   The secondary transfer unit receives an input of driving from the image forming apparatus main body via a helical gear, and the helical gear receives an input of driving so that the secondary transfer unit hits the supporting unit. The image forming apparatus according to claim 5.   The image forming apparatus according to claim 6, wherein the helical gear is disposed on a side opposite to a direction in which the secondary transfer unit is pulled out of the secondary transfer unit.

Images