Image forming apparatus

Abstract

To prevent bending of an air duct in a case where a configuration having a transfer unit that can be pulled out from a frame is adopted in a configuration in which an intermediate transfer belt is prevented from being affected by the heat of a fixing unit.SOLUTION: An air duct is provided in a transfer unit having an intermediate transfer belt, and the air duct can integrally be moved as the transfer unit moves.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to an electrophotographic image forming apparatus such as a copying machine, a printer, a facsimile machine, and a multi-function machine having a plurality of these functions.

Background Art

[0002] Conventional image forming apparatuses employ an intermediate transfer method in which a toner image is primarily transferred from a photoreceptor to an intermediate transfer belt at a primary transfer unit and then the toner image is secondarily transferred from the intermediate transfer belt to a recording material at a secondary transfer unit.

[0003] In an image forming apparatus adopting this intermediate transfer method, a so-called horizontal path structure may be used in which a fixing unit is arranged in a horizontal direction that is substantially horizontal with respect to a secondary transfer unit that transfers a toner image from an intermediate transfer belt to a recording material.

[0004] In an image forming apparatus adopting a horizontal path structure, heat generated from a fixing unit tends to accumulate in a space that is downstream of the secondary transfer unit in the conveyance direction of the recording material and below the intermediate transfer belt in the vertical direction.

[0005] Thus, when the intermediate transfer belt is affected by heat from the fixing unit, the state of the toner on the intermediate transfer body changes, making it impossible to transfer normally to the recording material, and there is a risk of image defects occurring.

[0006] Therefore, in Patent Document 1, a configuration is adopted in which a ventilation duct is arranged in a space that is downstream of the secondary transfer unit in the conveyance direction of the recording material and below the intermediate transfer belt in the vertical direction, and heat insulation is performed by forming an air flow.

[0007] Although Patent Document 1 describes an image forming apparatus having an image forming section including an intermediate transfer belt and a fixing unit within a single housing as an example, similar problems can be considered even with an image forming apparatus having multiple housings. In other words, the same problems can be considered even when an image forming apparatus is configured with two housings, such that a fixing unit is located in a second housing adjacent to a first housing having an intermediate transfer unit.

[0008] In the case of an image forming apparatus having multiple housings, the first housing has an opening for transferring recording material to the second housing, and the second housing has an opening for receiving recording material from the first housing. Therefore, there is a risk that heat from the fixing unit may accumulate in the space downstream of the secondary transfer section in the direction of recording material transport in the first housing, and below the intermediate transfer belt in the vertical direction, through each opening.

[0009] Even with this configuration, as in Patent Document 1, by arranging the air duct in a space downstream of the secondary transfer section in the transport direction and below the intermediate transfer belt in the vertical direction, the intermediate transfer belt can be prevented from being affected by the heat from the fixing unit. [Prior art documents] [Patent Documents]

[0010] [Patent Document 1] Japanese Patent Publication No. 2014-106284 [Overview of the Initiative] [Problems that the invention aims to solve]

[0011] On the other hand, the transfer unit, including the intermediate transfer belt, may be configured to be pullable forward from the device in order to facilitate maintenance work.

[0012] In this case, the frame supporting the transfer unit must have an opening on the front side that is large enough to allow the transfer unit to be pulled out.

[0013] Therefore, when fixing the air duct to the frame, it was not possible to support the air duct near the opening on the front side of the frame, and the unsupported end of the air duct would sag under its own weight, potentially causing deformation of the air duct.

[0014] Therefore, the present invention aims to suppress deflection of the air duct when employing a configuration that has a transfer unit that can be pulled out relative to the frame, in order to suppress the influence of heat from the fixing unit on the intermediate transfer belt. [Means for solving the problem]

[0015] The image forming apparatus according to the present invention comprises a photoreceptor, a transfer belt onto which a toner image formed on the photoreceptor is transferred, a primary transfer roller facing the photoreceptor via the transfer belt and forming a primary transfer nip portion for primary transfer of the toner image formed on the photoreceptor to the transfer belt, a secondary transfer inner roller provided below the primary transfer roller in the vertical direction and in contact with the inner circumferential surface of the transfer belt, and a tension roller provided between the secondary transfer inner roller and the primary transfer roller in the rotational direction of the transfer belt and for tensioning the transfer belt. A cleaning unit is provided downstream of the secondary transfer roller in the rotational direction of the transfer belt and cleans the outer surface of the transfer belt. The transfer unit comprises: a transfer unit having a transfer belt; a secondary transfer outer roller facing the secondary transfer inner roller via the transfer belt and forming a secondary transfer nip portion for secondary transfer of the toner image formed on the transfer belt to a recording material; a support portion that supports the transfer unit so as to be movable along the rotation axis direction of the secondary transfer inner roller; an air duct provided on the transfer unit having an air intake port; and a guide portion provided between the secondary transfer nip portion and the cleaning unit in the transport direction of the recording material in the secondary transfer nip portion for preventing the sheet from sticking to the transfer belt, wherein the air duct is provided integrally with the guide portion, and the air duct moves integrally with the transfer unit as the transfer unit moves relative to the support portion. [Effects of the Invention]

[0016] According to the present invention, in a configuration for suppressing the influence of heat from the fixing unit on the intermediate transfer belt, when adopting a configuration having a transfer unit that can be pulled out with respect to the frame, the bending of the air duct can be suppressed.

Brief Description of the Drawings

[0017] [Figure 1] Schematic cross-sectional view of an image forming system including an image forming apparatus according to the first embodiment. [Figure 2] Schematic cross-sectional view of the image forming unit of the image forming apparatus according to the first embodiment. [Figure 3] Schematic cross-sectional view of the fixing and conveying unit of the image forming apparatus according to the first embodiment. [Figure 4] Perspective view showing the configuration of the air duct according to the first embodiment. [Figure 5] Perspective view showing the jam processing and maintenance work procedures of the conveying unit according to the first embodiment. [Figure 6] Perspective view showing the state where the transfer unit according to the first embodiment is pulled out. [Figure 7] Perspective view showing the replacement work procedure of the intermediate transfer belt according to the first embodiment. [Figure 8] Cross-sectional view showing the joint portion between the first duct and the second duct of the air duct according to the first embodiment. [Figure 9] Cross-sectional view showing the joint portion between the first duct and the third duct of the air duct according to the first embodiment. [Figure 10] Schematic cross-sectional view of the image forming apparatus according to the second embodiment. [Figure 11] Schematic cross-sectional view showing the configuration of the air duct according to the second embodiment. [Figure 12] Perspective view showing the jam processing and maintenance work procedures of the conveying unit according to the second embodiment. [Figure 13] Perspective view showing the state where the transfer unit according to the second embodiment is pulled out. [Figure 14] Perspective view showing the transfer belt unit according to the second embodiment. [Figure 15] Perspective view showing the replacement work procedure of the intermediate transfer belt according to the second embodiment. [Figure 16] A cross-sectional view showing the joint of the heat supply, fixing, and exhaust duct of the second embodiment. [Figure 17] A schematic perspective view showing a prior art air duct. [Modes for carrying out the invention]

[0018] Embodiments of the present invention will be described below with reference to the drawings. However, the dimensions, materials, shapes, and relative arrangements of the components described in the following embodiments should be appropriately changed depending on the configuration of the device to which the present invention is applied and various conditions, and the scope of the present invention is not intended to be limited to those.

[0019] <First Embodiment> (Image forming system) Figure 1 is a schematic cross-sectional view of an image forming system 100 including an image forming apparatus 101 according to an embodiment of the present invention. The image forming apparatus 101 shown in Figure 1 consists of an image forming unit 102 that transfers a toner image to a fed sheet S, and a fixing and transport unit 103 that fixes the transferred toner image to the sheet S. The image forming unit 102 and the fixing and transport unit 103 are each in an independent housing and are movable by a plurality of casters provided on each. With this configuration, even large devices can be packaged and transported in a separated state for each housing, improving the workability during logistics until installation.

[0020] An image forming unit 102 is selectively connected to the upper part of the image forming unit 102. This unit includes an image reader 104 for reading original images and an image feeder 105 for feeding multiple stacked originals one by one to the image reader 104.

[0021] Upstream of the image forming unit 102 in the sheet transport direction, one of the following feeding devices can be selectively connected: a large-capacity feeding device 106 having multiple sheet storage compartments, a manual feeding device (not shown), or a long-sheet feeding device (not shown) capable of accommodating long sheets. Further upstream of the large-capacity feeding device 106, one of the following feeding devices (not shown) can be selectively connected in multiple units: a large-capacity feeding device, a manual feeding device, or a long-sheet feeding device.

[0022] A sensing device 107 is selectively connected to the downstream side of the fixing and transport unit 103 in the sheet transport direction. This sensing device reads the toner image formed on one or both sides of the sheet S after fixing. The sensing device 107 detects deviations in image density and image position and reads the image on the recording material in order to perform feedback correction on the image signal transmitted to the image forming unit 102.

[0023] Further downstream of the fixing and transport unit 103 or the sensing device 107, one or more of various sheet processing devices (not shown), such as inserters, punchers, perfect binding machines, high-capacity stackers, folding machines, finishers, trimmers, etc., can be selectively connected.

[0024] As described above, the image forming apparatus 101 of this embodiment has various optional devices selectively connected to the upstream and downstream directions in the sheet transport direction. This makes it possible to output inline products with various post-processing treatments applied to various materials, and provides an image forming system 100 that is excellent in terms of high productivity, high image quality, high stability, and high functionality. In this embodiment, the direction of arrow X in the figure is the width direction (left and right direction) of the image forming system 100, the direction of arrow Y is the front and back direction, and the direction of arrow Z is the vertical direction (up and down direction).

[0025] (Image forming apparatus: Image forming unit 102) Figure 2 is a schematic cross-sectional view of the image forming unit 102 in the image forming apparatus 101 of this embodiment. The image forming unit 102 shown in Figure 2 includes a plurality of image forming stations 200 that form different toner images for each color: yellow (Y), magenta (M), cyan (C), and black (K). Figure 2(a) is a schematic cross-sectional view of the entire image forming unit 102. Figure 2(b) is a schematic cross-sectional view of image forming stations 200Y, M, and C. Figure 2(c) is a schematic cross-sectional view of image forming station 200K.

[0026] As shown in Figure 2(a), the photosensitive drum 201 in each imaging station 200 is uniformly charged on its surface by the primary charger 202, and then an electrostatic latent image is formed by the laser scanner 203, which is driven based on the transmitted image information signal. The latent image formed here is developed as a toner image by the developer 204. The photosensitive drum 201 in this embodiment is an example of a photoreceptor.

[0027] The toner consumed during development is then replenished to each developer unit 204 as needed via the toner supply path 206 from the toner bottle 205. Each image station 200Y, M, and C differs only in the color of toner used; their configurations are all the same. In the following, the designations Y, M, C, and K will be omitted when describing the common configuration. Note that image station 200K has a configuration that has some functions different from image stations 200Y, M, and C, so the differences will be described later.

[0028] The toner image on the photosensitive drum 201 is sequentially transferred onto the intermediate transfer belt 208 at each primary transfer nip N1 by the primary transfer roller 207, which applies a predetermined pressure and electrostatic load bias. In other words, the toner image is transferred to the outer surface of the intermediate transfer belt 208 by the primary transfer roller 207, which contacts the inner surface of the intermediate transfer belt 208. The intermediate transfer belt 208 is rotated clockwise in the figure by the drive roller 220 while tension is applied to it by the tension roller 15 in the direction from the inner surface to the outer surface of the intermediate transfer belt 208. Any small amount of residual toner remaining on the photosensitive drum 201 after transfer is removed by the photosensitive drum cleaner 209, in preparation for the next image formation. The removed residual toner is collected in the toner collection container 211 via the toner collection path 210.

[0029] Meanwhile, sheets S, fed one by one from either the sheet storage unit 212 inside the image forming unit 102 or a paper feeder connected to the outside of the aforementioned image forming apparatus 101, are corrected for skew by forming a loop with their leading edge following the nip portion of the registration roller 213. Subsequently, the registration roller 213 transports the sheets S to the secondary transfer unit in synchronization with the toner image on the intermediate transfer belt 208.

[0030] The toner image on the intermediate transfer belt 208 is transferred to the sheet S by a secondary transfer nip N2 consisting of a secondary transfer inner roller 214 and a secondary transfer outer roller 215, which applies a predetermined pressure and electrostatic load bias. In other words, the toner image is transferred to the outer surface of the intermediate transfer belt 208 by the secondary transfer inner roller 214, which is in contact with the inner surface of the intermediate transfer belt 208, and the secondary transfer outer roller 215, which is located on the outer surface of the intermediate transfer belt 208. Any small amount of residual toner remaining on the intermediate transfer belt 208 after transfer is removed by the intermediate transfer belt cleaner 216, in preparation for the next image formation.

[0031] The intermediate transfer belt cleaner 216 has a blade 216a that contacts the outer circumferential surface of the intermediate transfer belt 208 at a position opposite to the drive roller 220, and a recovery unit 216 that collects the toner scraped off by the blade 216a. The remaining toner removed by the intermediate transfer belt cleaner 216 is collected in the toner recovery container 211 via the toner recovery path 210. The intermediate transfer belt cleaner 216 is an example of a cleaning unit that cleans the outer circumferential surface of the intermediate transfer belt 208.

[0032] The sheet S onto which the toner image has been transferred is then transported to the downstream fixing transport section 103 by the pre-fixing transport belts 217a and 217b.

[0033] (Image forming apparatus: Black and white image formation) In addition to full-color image formation using all of the aforementioned Y, M, C, and K imaging stations 200, the image forming apparatus 101 of this embodiment can also perform monochrome image formation using only the K imaging station 200K.

[0034] During black and white image formation, the primary transfer roller 207, primary transfer auxiliary roller 218, and intermediate transfer belt 208 are separated from the intermediate transfer belt 208 by a separation mechanism (not shown). The imaging stations 200Y, 200M, and 200C, whose primary transfer nip sections Y, M, and C are separated, can stop their rotational drive. That is, unnecessary wear of parts due to unnecessary rotational drive can be prevented in the imaging stations 200Y, 200M, and 200C of Y, M, and C, thereby extending their lifespan.

[0035] On the other hand, the photosensitive drum 201K is configured with a larger diameter, which is more suitable for a longer lifespan than the photosensitive drums 201Y, 201M, and 201C. Also, as shown in Figure 2(c), the primary charger 202K is configured with a non-contact method using a corona charger, which is more suitable for a longer lifespan than the contact method using roller chargers used in the primary chargers 202Y, 202M, and 202C. Furthermore, the toner bottle 205K is configured with a larger capacity, which is more suitable for a longer lifespan than the toner bottles 205Y, 205M, and 205C.

[0036] With the above configuration, even for users who frequently use black and white image formation, it is possible to prevent the maintenance interval of the frequently used K image formation station 200K from becoming shorter than that of the less frequently used Y, M, and C image formation stations 200Y, 200M, and 200C.

[0037] Furthermore, the large-diameter drum configuration using the corona charger 202K has a wider charging width and is more suitable for high-speed operation than the small-diameter drum configuration using the roller chargers 202Y, 202M, and 202C, thus improving productivity during monochrome image formation.

[0038] In the image forming unit 102, where different conditions exist among the image forming stations 200, differences in shape and wear may result in differences in the amount of toner charge on the photosensitive drum 201. If there are differences in the amount of toner charge, the transfer of the toner image to the sheet S may not be uniform in the secondary transfer process, resulting in image defects. Therefore, the photosensitive drum 201K of K is equipped with a pre-transfer charger 219 consisting of a corona charger to match the amount of toner charge with the photosensitive drums 201Y, 201M, and 201C of Y, M, and C. Here, the pre-transfer charger 219 is an example of another charging unit provided between the developer 204K and the photosensitive drum cleaner 209K in the rotational direction of the photosensitive drum 201.

[0039] As described above, according to the configuration of this embodiment, an image forming apparatus 101 can be provided that excels in high productivity, high image quality, high stability, and long lifespan not only in full-color image formation but also in monochrome image formation.

[0040] (Image forming apparatus: Fixing and transport unit 103) Figure 3 is a schematic cross-sectional view of the fixing and transport unit 103 in the image forming apparatus 101 of this embodiment. The fixing unit 301 shown in Figure 3 fixes the toner image on the sheet S, which is transported from the image forming unit 102, to the sheet S by heating and pressurizing it.

[0041] In this embodiment, the fixing unit 301 has a heating roller 301a on its vertically upper side, which is heated by a heating element (not shown), and a pressure roller 301b on its vertically lower side, which presses the sheet against the heating roller 301a. The sheet S on which the toner image is formed is heated and pressurized at the fixing nip formed by the heating roller 301a and the pressure roller 301b, thereby fixing the toner image. The heating roller 301a and the pressure roller 301b then grip and convey the sheet downstream in the sheet conveying direction while heating and pressurizing it. Here, a fixing unit 301 consisting of a pair of rollers has been described as an example, but a fixing unit 301 in which the fixing nip is formed by a conveyor belt may also be used. Note that the heating roller 301a is an example of a first rotating body, and the pressure roller 301b is an example of a second rotating body.

[0042] The sheet S, heated by the fixing unit 301, is cooled by the heat absorption of the heat sink 303, which is in contact with the inner surface of the conveyor belt 30a of the cooling unit 302, while being conveyed by the conveyor belts 302a and 302b. After that, it is discharged via the paper discharge conveyor path 304 to the aforementioned sensing device 107 or an unshown post-processing device.

[0043] When discharging the front and back sides of the sheet S, the paper output reversal unit 305 performs a switchback transport, swapping the leading and trailing ends of the sheet S and discharging it via the paper output transport path 304 with its front and back sides reversed.

[0044] When image formation is performed on both sides of sheet S, the sheet S with the first image formed is transported via a switchback mechanism in the double-sided reversal unit 306, reversing the front and rear ends of the sheet S and transporting it to the double-sided transport path 307. Subsequently, it is rejoined by the registration roller 213 in sync with the timing of the subsequent sheet S fed by either the sheet storage unit 212 inside the image formation unit 102 or one of the externally connected paper feeding devices mentioned above. Then, image formation is performed on the second side using the same process as the first side, and it is discharged via the paper discharge transport path 304.

[0045] (Air supply duct configuration) As shown in Figures 1 and 2, in this embodiment, the image forming apparatus 101 has the air duct 1 arranged downstream of the secondary transfer nip section N2 and upstream of the fixing transport section 103 in the sheet transport direction.

[0046] Figure 17 is a perspective view showing the configuration of a conventional air duct. Note that, for illustrative purposes, units near the air duct, such as the intermediate transfer belt unit, are not shown in Figure 17. In a conventional image forming apparatus 100', a configuration may be adopted that allows the intermediate transfer belt unit, etc., to be pulled out to the front of the apparatus (arrow Y direction) for maintenance, etc. In this case, the main frame supporting the intermediate transfer belt unit must have an opening 100A' at the front of the apparatus for inserting and removing the unit.

[0047] In the conventional configuration, the air duct 1', positioned downstream of the secondary transfer section in the transport direction of the recording material and below the intermediate transfer belt in the vertical direction, is supported by the main frame that supports each unit of the image forming apparatus 100'. More specifically, the rear side of the air duct 1' is fixed to the rear plate 102' of the main frame, and the front side of the air duct 1' is supported by a duct fixing member 103 at one end in the width direction of the image forming apparatus 100'. The duct fixing member 103 is fixed to the left support column (not shown) of the main frame, or to a stay connecting the left support column and the rear plate 102. On the other hand, near the center in the width direction (arrow X direction) of the apparatus, there is no main frame in order to provide an opening 100A'. Therefore, the end 11' of the air duct 1' located on the front side of the apparatus and towards the center in the width direction was not supported by the main frame.

[0048] Therefore, the free end 11' of the conventional air duct 1' was prone to bending under its own weight, which could cause the air duct 1' to deform. In addition, when pulling out the conveying unit 9' located below the intermediate transfer belt unit, friction with the top surface of the heat conveying unit 9' could impair the user's operability.

[0049] Therefore, in this embodiment, in order to suppress deformation due to the weight of the air duct, which is positioned downstream of the secondary transfer section in the transport direction of the recording material and below the intermediate transfer belt in the vertical direction, the air duct is fixed to the intermediate transfer unit.

[0050] Figure 4 is a perspective view showing the configuration of the air supply duct 1 in this embodiment. As shown in Figure 4, the air supply duct unit 1 in this embodiment is composed of three members: a first duct 2, a second duct 3, and a third duct 4.

[0051] The first duct 2 is positioned vertically below the intermediate transfer belt 208 and above the pre-fixing conveyor belts 217a and 217b. The first duct 2 is fixed to the intermediate transfer belt cleaner 216, shown by the dashed line in Figure 4, by fastening screws to the four positioning holes 2a shown in Figure 4.

[0052] In Figure 4, the first duct 2 is fixed to the front side of the intermediate transfer belt cleaner 216 by fastening screws to two positioning holes 2a on the front side (arrow Y direction). Also in Figure 4, the first duct 2 is fixed to the back side of the intermediate transfer belt cleaner 216 by fastening screws to two positioning holes 2a on the back side (arrow Y direction). In other words, in the front-to-back direction of the image forming apparatus 101, the first duct 2 is fixed so as to sandwich the intermediate transfer belt cleaner 216.

[0053] In this way, the first duct 2 is supported at approximately four corners in a balanced manner by screws inserted through four positioning holes 2a. Therefore, it is possible to prevent the end of the first duct 2 from bending due to its own weight, as in the conventional example shown in Figure 17. Thus, the jam processing space below is not narrowed due to the bending of the air supply duct 1, and a wide jam processing space is maintained on the pre-fixing conveyor belt 217, making it possible to provide an image forming apparatus 101 that can improve the jam processing operability by the user.

[0054] Next, the airflow of the ventilation duct unit 1 will be explained. An opening 2b is formed at the front end of the first duct 2, and it communicates with the louver hole 5a (Figure 5) formed in the front door 5 of the image forming unit 102, becoming the first air intake port for drawing outside air into the ventilation duct 1. As shown in Figure 1, the first duct 2 is positioned downstream of the secondary transfer unit in the direction of transporting the recording material, and below the intermediate transfer belt 208 in the vertical direction. In other words, the first duct 2 is positioned vertically below the portion of the intermediate transfer belt 208 that is stretched between the secondary transfer roller 214 and the drive roller 220. Therefore, by forming an airflow within the first duct 2, it is possible to block the heat from the fixing unit leaking from the opening of the fixing transport unit 103, and the intermediate transfer belt 208 from being affected by the heat of the fixing unit can be suppressed.

[0055] Furthermore, the second duct 3 is joined to the first duct 2 on the side of the intermediate transfer belt 208, positioned between the intermediate transfer belt 208 and the fuser 301 in the width direction (arrow X direction), and extends vertically (arrow Z direction). The second duct 3 is supported on the side of the housing (not shown) of the image forming unit 102. An opening 3a is formed at the upper end of the second duct 3, which communicates with a louver hole formed on the upper surface of the housing (not shown) of the image forming unit 102, and serves as a second air intake for drawing outside air into the air supply duct 1.

[0056] In this way, by providing the second duct 3 between the intermediate transfer belt 208 and the fixing unit 301 in the width direction of the apparatus, it is possible to suppress the influence of heat transmitted from the fixing unit 301 through the side of the housing on the intermediate transfer belt 8.

[0057] Furthermore, the third duct 4 is joined to the first duct 2 at a position behind the intermediate transfer belt 208 in the front-rear direction (arrow Y direction). In other words, the third duct 4 is positioned adjacent to the rear surface of the image forming unit 102. The third duct 4 is supported by the rear surface of the housing (not shown) of the image forming unit 102. An opening 4a is formed at the rear end of the third duct 4. The opening 4a communicates with a louver hole formed in the rear cover (not shown) of the image forming unit 102 and serves as the exhaust port for the air blower duct 1.

[0058] A blower fan 6 is installed inside the third duct 4. The outside air taken into the blower duct 1 from the first intake port 2b and the second intake port 3a is efficiently exhausted from the exhaust port 4a by the blower fan 6. Therefore, the airflow formed inside the blower duct 1 can suppress the influence of heat from the fixing unit 301 on the intermediate transfer belt 208.

[0059] The configuration of the air duct 1 described above makes it possible to block the influence of heat from the fuser 301 on the image forming unit 102. In other words, it is possible to prevent image defects caused by changes in the charge characteristics due to overheating of the toner in the image forming unit 102, malfunctions such as toner clogging caused by deterioration of fluidity, and downtime required to cool the overheated toner. Therefore, it is possible to provide an image forming apparatus 101 with excellent image quality, high stability, high productivity, and long lifespan.

[0060] (Procedures for jamming and maintenance of conveying units) Next, the maintenance procedure for the transport unit 7 will be explained using Figure 5.

[0061] First, as shown in Figure 5(a), the front door 5 of the image forming unit is opened in the direction of arrow A. Next, as shown in Figure 5(b), the handle 7a of the transport unit 7 is rotated in the direction of arrow B. This operation releases the lock of the transport unit 7 from the device housing (support frame), allowing the transport unit 7 to be pulled out to the front of the device indicated by arrow C by a sliding mechanism (not shown). Inside the image forming unit 102, a support frame is provided as a support part that supports the transport unit 7 so that it can slide. Note that the direction of arrow C is the rotation axis direction of the secondary transfer outer roller 215 and the rotation axis direction of the secondary transfer inner roller 21.

[0062] In the position where the transport unit 7 is extended (Figure 5(b)), the user can perform jam removal work inside the transport unit 7 by opening the transport guides (not shown) located above and below the transport unit 7. In addition, a service technician can perform maintenance such as cleaning the inside of the transport unit and replacing parts. The transport unit 7 has transport rollers that are located vertically below the intermediate transfer belt 8, such as the pre-fixing transport belt 217b, the secondary transfer outer roller 215, and the resist roller 213.

[0063] (Procedure for replacing the intermediate transfer belt) Next, the procedure for replacing the intermediate transfer belt 208 will be explained using Figure 6. As shown in Figure 6(a), the service technician rotates the handle 8a of the transfer unit 8 in the direction of arrow D. This operation moves the transfer belt unit 9 inside the transfer unit 8 downward, separating the intermediate transfer belt 208 from the photosensitive drum 201. This makes it possible to pull the transfer unit 8 forward of the image forming apparatus 101, indicated by arrow E, relative to the support frame of the image forming unit 102. The handle 8a is an example of an operating lever that, when rotated, moves the intermediate transfer belt 208 away from the photosensitive drum.

[0064] The direction of arrow E is the rotation axis direction of the secondary transfer roller 21. The support frame of the image forming apparatus also supports the paper feed cassette 212 so that it can slide forward.

[0065] As shown in Figure 6(a), when the transfer unit 8 is pulled out, the internal transfer belt unit 9 can be removed upward from the support frame 8b of the transfer unit 8.

[0066] The transfer belt unit 9 includes an intermediate transfer belt 208, a plurality of rollers that tension the intermediate transfer belt 208, the intermediate transfer belt 208, a transfer cleaner unit 12, and an intermediate transfer post-upper guide 13. The transfer cleaner unit 12 includes an intermediate transfer belt cleaner 216 and a first duct 2 fixed to the intermediate transfer belt cleaner 216 as described above.

[0067] Although the perspective view shown in Figure 6(a) shows both the transport unit 7 and the transfer unit 8 pulled out to the front of the apparatus, it is also possible to pull out only the transfer unit 8 while the transport unit 7 is installed in its mounting position within the image forming apparatus (as shown in Figure 5(a)).

[0068] Figure 6(b) shows the transfer unit 9 removed from the support frame 8b of the transfer unit 8. As shown in Figure 6(b), the transfer unit 9 has a front plate 10 provided on the front side and a rear plate 812 provided on the back side. The front plate 10 and the rear plate 11 rotatably support a plurality of rollers that tension the intermediate transfer belt 208. Therefore, the intermediate transfer belt 208 is located between the front plate 10 and the rear plate 11 in the front-rear direction (arrow Y direction).

[0069] Furthermore, the front plate 10 and the rear plate 11 support the aforementioned intermediate transfer belt cleaner 216 by fastening screws (not shown). In other words, the first duct 2, which is fixed to the intermediate transfer belt cleaner 216, is indirectly supported by the front plate 10 and the rear plate 11. As shown by the dashed line in Figure 6(b), the opening 2b of the first duct 2 is located in front of the front plate 10 in the front-rear direction (arrow Y direction). In other words, it is located outside the end of the intermediate transfer belt 208 in the direction of the rotation axis of the secondary transfer inner roller 214. This ensures that the intake of air from the opening 2b of the first duct 2 is not obstructed in the configuration in which the first duct 2 is supported by the transfer unit 9.

[0070] In this manner, the first duct 2 is positioned and fixed to the front plate 10 and the rear plate 11 of the transfer unit 9. Therefore, when the transfer unit 9 is withdrawn from the image forming unit 102, the first duct 2 is withdrawn together with the transfer unit 9 that supports the intermediate transfer belt 208.

[0071] Furthermore, the first duct 2 is fixed to the intermediate transfer belt cleaner 216. As a result, even when the transport unit 7 is pulled out to the position shown in Figure 6(b), the first duct 2 does not bend under its own weight and does not come into contact with the top surface of the transport unit 7 when the transport unit 7 is slid. Therefore, the operability when the user slides the transport unit 7 can be improved.

[0072] Next, as shown in Figure 6(b), the transfer cleaner unit 12 and the secondary transfer upper guide 13, which are provided on the outer peripheral surface side of the intermediate transfer belt 208, are removed from the mounting positions indicated by the dashed lines in the removed transfer belt unit 9. As a result, all components that are arranged across the front plate 10 and the rear plate 11 of the transfer belt unit 9, such as the transfer cleaner unit 12 and the secondary transfer upper guide 14, are removed, and the entire outer peripheral surface of the intermediate transfer belt 208 is exposed.

[0073] Next, as shown in Figure 7(a), the cam lever 14 is rotated in the direction of arrow F. This operation causes the tension roller 15, which had been applying tension to the intermediate transfer belt 208, to move away from the inner surface of the intermediate transfer belt 208 in the direction of arrow G, and the tension applied to the intermediate transfer belt 208 is released by the force of a spring (not shown).

[0074] Finally, as shown in Figure 7(b), the intermediate transfer belt 208, which is now released and loosened, is removed from the transfer belt unit 9 in the direction of arrow H. Then, a new intermediate transfer belt 208 is installed using the reverse procedure described above, and the replacement of the intermediate transfer belt 208 is completed.

[0075] As described above, the first duct 2 in this embodiment can be removed as part of the transfer cleaner unit 12, together with the intermediate transfer belt cleaner 216. Therefore, even if the first duct 2, which is part of the air supply duct 1, is supported inside the transfer belt unit 9, the procedure for replacing the intermediate transfer belt by a service technician does not increase. This makes it possible to provide an image forming apparatus 101 with excellent maintainability while minimizing working time.

[0076] (Configuration of the joint in the air supply duct) Figure 8 is a cross-sectional view showing the joint 1a between the first duct 2 and the second duct 3 of the air supply duct 1, and Figure 9 is a cross-sectional view showing the joint 1b between the first duct 2 and the third duct 4 of the air supply duct 1.

[0077] Figure 8(a) shows the mounting state in which the transfer unit 8 is pressed upward and the outer surface of the intermediate transfer belt 208 is in contact with the photosensitive drum 201. In other words, the transfer unit 8 is in the state shown in Figure 5(a). In this state, the joint 1a of the first duct 2 and the joint 1b of the second duct 3 are in contact with each other to form a duct.

[0078] Figure 8(b) shows the state in which the transfer unit 8 has moved downward, and the outer surface of the intermediate transfer belt 208 and the photosensitive drum 201 are separated. In other words, the transfer unit 8 is in the state shown in Figure 6(a). In this state, the first duct 2 moves downward together with the transfer unit 8, as indicated by arrow I in Figure 8(b), so that the joint 1a of the first duct 2 and the second duct 3 is separated. Subsequently, the first duct 1 is pulled out towards the front side of Figure 8(b) (arrow Y direction) together with the transfer unit 8, as shown in Figure 6(b), but because there is a sufficient distance between it and the second duct 3 that remains on the main body of the device, the ducts do not rub against each other and impair operability.

[0079] Figure 9(a) shows the mounting state in which the transfer unit 8 is pressed upward and the outer surface of the intermediate transfer belt 208 is in contact with the photosensitive drum 201. In other words, the transfer unit 8 is in the state shown in Figure 5(a). In this state, the joint 1c of the first duct 2 and the joint 1d of the third duct 4 are in contact with each other to form a duct.

[0080] Figure 9(b) shows the state in which the transfer unit 8 has moved downward, and the outer surface of the intermediate transfer belt 208 and the photosensitive drum 201 are separated. In other words, the transfer unit 8 is in the state shown in Figure 6(a). In this state, the first duct 2 moves downward together with the transfer unit 8 as indicated by arrow I in Figure 9(b), so that the joint 1c of the first duct 2 and the joint 1d of the third duct 4 are separated. Note that in the state shown in Figure 9(b), the lower end 1cc of the upper vertical joint 1c of the first duct 2 is located higher than the upper end 1dd of the lower vertical joint 1d of the third duct 4.

[0081] Subsequently, the first duct 1 is pulled out together with the transfer unit 8 as shown in Figure 6(a) towards the front of the device indicated by arrow J in Figure 9(b). However, since there is sufficient distance between it and the third duct 4 remaining on the main body of the device, the ducts do not rub against each other and impair operability.

[0082] In other words, the joint 1a of the first duct 2 and the joint 1b of the second duct 3, and the joint 1c of the first duct 2 and the joint 1d of the third duct 4, respectively, transition from a joined state to a separated state in accordance with the separation movement between the intermediate transfer belt 208 and the photosensitive drum 201. Furthermore, the joint 1a of the first duct 2 and the joint 1b of the second duct 3, and the joint 1c of the first duct 2 and the joint 1d of the third duct 4 become separated when the handle 8a is rotated in the direction of arrow D when the transfer unit 8 is pulled out. As a result, when the intermediate transfer unit 8 is pulled out, the joined states of the first duct 2, the second duct 3, and the third duct 4 are released, thus preventing interference between the ducts when the intermediate transfer unit 8 is pulled out. Therefore, the ducts do not rub against each other and impair the operability when pulling out the intermediate transfer unit 8.

[0083] In this case, if an elastic sealing member 16 is provided at the contact portion 1a of the first duct 2 and the contact portion 1b of the second duct 3, and at the contact portion 1c of the first duct 2 and the contact portion 1d of the third duct 4, the airtightness at the duct joints 1a and 1b is improved. Therefore, not only is the heat shielding efficiency of the air supply duct 1 improved, but toner scattering and transport jams caused by air leaking out of the air supply duct 1 can be prevented, thus providing an image forming apparatus 10 with excellent stability.

[0084] <Second Embodiment> Next, a second embodiment will be described. In this embodiment, unlike the first product, the image forming apparatus is configured from a single housing. That is, an image forming apparatus is used in which the intermediate transfer belt and the fixing unit are housed within a single housing.

[0085] (Image forming apparatus) Figure 10 is a schematic cross-sectional view of the image forming apparatus in this embodiment. The image forming apparatus 500 in this embodiment is a tandem-type intermediate transfer image forming apparatus in which image forming units 501Y, 501M, 501C, and 501K are arranged in series on the horizontal part of the intermediate transfer belt 31. Then, in response to an image signal transmitted from an external device or a reading device as shown in the figure, a full-color image is formed on the sheet material S using an electrophotographic method.

[0086] The image forming units 501Y, 501M, 501C, and 501K have photosensitive drums 50Y, 50M, 50C, and 50K, respectively, on which yellow, magenta, cyan, and black toner images are formed. Since the image forming units 501Y, 501M, 501C, and 501K have the same configuration but differ only in the color of the toner image formed, the yellow image forming unit 501Y will be used as an example in this explanation.

[0087] Surrounding the photosensitive drum 50Y are a charger 51Y for charging the photosensitive drum 50Y, an exposure device 55Y for irradiating the photosensitive drum 50Y with light to form a latent image, and a developer 52Y for transferring toner to the latent image formed on the photosensitive drum 50Y to form a toner image.

[0088] Furthermore, the toner image formed by the photosensitive drum 50Y is temporarily transferred to the intermediate transfer belt 60 by the primary transfer roller 61Y. Here, the nip formed by the photosensitive drum 50Y and the primary transfer roller 61Y via the intermediate transfer belt 60 is the primary transfer nip N1.

[0089] Downstream of the primary transfer nip in the rotational direction of the photosensitive drum 50Y, a cleaning device 53Y is provided to remove toner remaining on the photosensitive drum 11Y after the primary transfer of the toner image.

[0090] The intermediate transfer belt 60 is taut and rotated by a drive roller 62, a tension roller 63, and a secondary transfer inner roller 64 for performing secondary transfer. The drive roller 62 is driven by a motor (not shown), and the rotation of the drive roller 62 rotates the intermediate transfer belt 60. The tension roller 63 is subjected to tension from the inner circumferential surface to the outer circumferential surface of the intermediate transfer belt 60 by a biasing member (not shown).

[0091] The intermediate transfer belt 60 transfers the toner image formed by each image forming unit 501 to the sheet via the secondary transfer outer roller 70, which is opposite the secondary transfer inner roller 64, after the toner image has been transferred in the primary transfer unit. Here, the nip portion formed by the secondary transfer inner roller 64 and the secondary transfer outer roller 70 via the intermediate transfer belt 60 is the secondary transfer nip N2. The drive roller 62 is provided between the secondary transfer inner roller 64 and the primary transfer roller 61 in the rotational direction of the intermediate transfer belt 208, and is an example of a tension roller that tensions the intermediate transfer belt 208.

[0092] Meanwhile, the sheets S stored in the paper feed cassettes 80a, 80b, and 80c are transported to the paper feed transport path 71 by the rotation of the paper feed rollers 81a, 81b, and 81c. The sheets S transported along the paper feed transport path 71 are then fed to the secondary transfer section, which is formed by the secondary transfer inner roller 64 and secondary transfer outer roller 70, in time with the toner image on the intermediate transfer belt 60 by the registration roller 72. As a result, a toner image is formed on the sheet material S by the secondary transfer section. After secondary transfer, any remaining toner on the intermediate transfer belt 31 is removed by the cleaner unit 65. The cleaner unit 65 is an example of a cleaning unit that cleans the outer surface of the intermediate transfer belt 80.

[0093] The cleaner unit 65 has a blade 36 that contacts the outer surface of the intermediate transfer belt 60 at a position opposite to the drive roller 62, a recovery unit 37 that recovers the toner scraped off by the blade 36, and a recovered toner transport screw 38 that transports the recovered toner.

[0094] Subsequently, the sheet S onto which the toner image has been transferred is transported to the fixing unit 90 by a transport belt 73. In the fixing unit 90, the toner image is fixed to the surface of the sheet material S by heating and pressing at a fixing nip section formed by a heating roller 91 and a pressure roller 92, which are heated by a heating unit (not shown). Here, the heating roller 91 is an example of a first rotating body, and the pressure roller 92 is an example of a second rotating body. In this embodiment, both the heating roller 91 and the pressure roller 92 are rollers, but a rotating body such as a belt may also be used.

[0095] In the case of single-sided printing, the sheet S, on which the toner image has been fixed, is ejected to the output tray 75 via the output transport path 74. In the case of double-sided printing, the sheet is transported via the inversion transport path 76, and is then transported again to the secondary transfer unit with its front and back sides reversed, so that an image is formed on both sides of the sheet S. After that, the toner image is fixed by the fuser unit 90, as in the case of single-sided printing, and the sheet is ejected to the output tray 75.

[0096] (Fixed heat exhaust duct configuration) Next, the fixing heat exhaust duct configuration of the image forming apparatus according to the present invention will be explained using Figure 11.

[0097] In this embodiment, the fixing heat exhaust duct 600 is provided downstream of the secondary transfer section in the sheet transport direction and between the intermediate transfer belt 60 and the fixing unit 90 in the vertical direction. In other words, the fixing heat exhaust duct 600 is provided in the space downstream of the secondary transfer section in the sheet transport direction and below the intermediate transfer belt 60 in the vertical direction. To put it another way, the fixing heat exhaust duct 600 is positioned vertically below the portion of the intermediate transfer belt 60 that is stretched between the secondary transfer roller 64 and the drive roller 62.

[0098] As a result, an airflow is formed inside the fuser heat exhaust duct 600, which blocks the heat emitted from the fuser unit 90 and suppresses the temperature rise of the intermediate transfer belt 60. Furthermore, by blocking the heat emitted from the fuser unit 90, the temperature rise around the photosensitive drum 50 that is in contact with the intermediate transfer belt 60 is suppressed.

[0099] The fixing heat exhaust duct 600 draws air into the duct through an intake port 601 located upstream of the fixing nip TN of the fixing unit 90 and an intake port 602 located downstream of the fixing nip TN. In the front-to-back direction of the image forming apparatus 500, exhaust ports 603 and 604 are provided on the rear side of the fixing heat exhaust duct 600 to exhaust the air inside the duct.

[0100] The fixing heat exhaust duct 600 is then connected to the main body duct 880 (Figure 16), which is located at the rear of the main body and has a built-in fan. This creates an airflow inside the fixing heat exhaust duct 81, which draws in air through the intake ports 81a and 81b.

[0101] The air intake port 81a primarily draws in air near the inlet of the sheet material S of the heat fixing unit 5, while the air intake port 81b draws in air near the outlet of the sheet material S of the heat fixing unit 5, or around the recovered toner transport screw 37. This prevents the intermediate transfer belt 31, cleaning device 36, and recovered toner transport screw 37 from overheating, thereby suppressing image defects caused by toner solidification and other issues.

[0102] Furthermore, the fixed heat exhaust duct 600 has a double-turn upper guide 650. The double-turn upper guide 650 is an example of a guide section provided to prevent the sheet S, which is attached to the intermediate transfer belt 60, from reaching the cleaner unit 65.

[0103] For example, if the sheet material S is thin paper, after the sheet material S passes through the secondary transfer nip section N2 formed by the clamping between the secondary transfer inner roller 64 and the secondary transfer outer roller 70, the sheet may be attracted to the intermediate transfer belt 60 by the electrostatic attraction generated on the charged sheet S. In contrast, in this embodiment, the secondary transfer upper guide 650 is positioned to extend from upstream to downstream in the conveying direction of the secondary transfer nip section N2, thereby preventing the sheet S from sticking to the intermediate transfer belt 60.

[0104] This makes it possible to suppress the occurrence of image defects caused by sheets adhering to the intermediate transfer belt 60 reaching the cleaning unit 65, as well as the need for sheet removal work.

[0105] (Jam removal and maintenance procedures for the fixing and transport unit) Next, the fixing and transport unit attachment / detachment configuration of the image forming apparatus according to the present invention will be described using Figure 12.

[0106] When the image forming apparatus 500 experiences a sheet jam, or when performing maintenance due to durability issues, it is necessary to access the sheet material transport path inside the apparatus.

[0107] In this embodiment, after opening the front door 550 in the direction of arrow A, the lock handle 900a is rotated 90° in the direction of arrow B from the mounted state of the fixing and transport unit 900 shown in Figure 12(a). By operating this lock handle 900a, the lock of the fixing and transport unit 900 to the device housing (not shown) is released, and the fixing and transport unit 900 can be pulled out to the front of the device indicated by arrow C by a sliding mechanism (not shown). Inside the image forming apparatus 500, a support frame is provided as a support part that supports the fixing and transport unit 900 so that it can slide. Note that the direction of arrow C is the rotation axis direction of the secondary transfer outer roller 70 and the rotation axis direction of the secondary transfer inner roller 64.

[0108] When the transport unit 900 is extended relative to the support frame of the image forming apparatus 500, the user can perform jam removal work inside the fuser transport unit 900 by releasing the transport guides (not shown) located above and below the fuser transport unit 900. In addition, a service technician can perform maintenance such as cleaning the inside of the fuser transport unit 900 and replacing parts. The fuser transport unit 900 includes a transport belt 73, a fuser unit 90, a secondary transfer outer roller 70, and transport rollers such as a resist roller 72 that are located vertically below the intermediate transfer belt 60.

[0109] (Procedure for replacing the intermediate transfer belt) Next, as shown in Figure 13, the service technician rotates the handle 800a of the transfer unit 800, which can be operated by the service technician, 90° in the direction of arrow D. This operation causes the transfer belt unit 810 inside the transfer unit 800 to move vertically downward, separating the intermediate transfer belt 80 from the photosensitive drum 50. This makes it possible to pull the transfer unit 800 forward relative to the support frame of the image forming apparatus 500, as indicated by arrow E. The handle 800a is an example of an operating lever that, when rotated, moves the intermediate transfer belt 80 away from the photosensitive drum 50.

[0110] Furthermore, the direction of arrow E is the rotation axis direction of the secondary transfer roller 64. The support frame of the image forming apparatus also supports the paper feed cassettes 80a to 80c so that they can slide forward.

[0111] As shown in Figure 13, when the transfer unit 800 is pulled out, the internal transfer belt unit 810 can be removed from above relative to the support frame 800b of the transfer unit 800.

[0112] In this embodiment, the transfer belt unit 810 includes an intermediate transfer belt 60, a plurality of rollers for tensioning the intermediate transfer belt 208, a cleaner unit 65, and an intermediate transfer post-upper guide 13. The transfer cleaner unit 12 includes an intermediate transfer belt cleaner 216 and the aforementioned fixing heat exhaust duct 600.

[0113] Although the perspective view shown in Figure 13 shows both the fixing and transporting unit 900 and the transfer unit 800 pulled out to the front of the device, it is also possible to pull out only the transfer unit 800 while the fixing and transporting unit 900 is installed in its mounting position.

[0114] Figures 14(a) and 14(b) show the transfer belt unit 810 removed from the support frame 800b of the transfer unit 800, with Figure 14(a) being a perspective view from the front and Figure 14(b) being a perspective view from the back.

[0115] As shown in Figures 14(a) and 14(b), the transfer unit 800 has a front plate 811 provided on the front side and a rear plate 812 provided on the back side. The front plate 811 and the rear plate 812 rotatably support the drive roller 62, the tension roller 63, and the secondary transfer internal roller 64. Therefore, the intermediate transfer belt 60 is located between the front plate 811 and the rear plate 812 in the front-rear direction (arrow Y direction).

[0116] As shown in Figure 14(a), the fixing heat exhaust duct 600 has front positioning parts 600a and 600b located on the front side in the front-rear direction (arrow Y direction), which are inserted into holes 811a and 811b of the front plate 811, respectively. This positions the fixing heat exhaust duct 600 relative to the front plate 811. In this embodiment, the front positioning parts 600a and 600b are pins inserted through the holes 811a and 811b.

[0117] Furthermore, as shown in Figure 14(b), the fixed heat exhaust duct 600 is fixed by screws b1 and b2 with rear positioning parts 600c and 600d, which are located on the rear side in the front-rear direction, positioned relative to the rear plate 812.

[0118] In this manner, the fixing heat exhaust duct 600 is positioned and fixed to the front plate 811 and the rear plate 812 of the transfer belt unit 810, respectively. Therefore, when the transfer unit 800 is withdrawn from the image forming apparatus 500, the fixing heat exhaust duct 600 is withdrawn together with the transfer belt unit 810 that supports the intermediate transfer belt 60.

[0119] Furthermore, the fixing heat exhaust duct 600 is fixed to the front plate 811 and the rear plate 812 at both its front and rear ends. This configuration provides balanced support for approximately all four corners of the fixing heat exhaust duct 600, preventing the bending of the four corner ends of the fixing heat exhaust duct 600 due to its own weight, as seen in the conventional example shown in Figure 17. In addition, even when the fixing transport unit 900 is pulled out to the position shown in Figure 12(b), the fixing heat exhaust duct 600 does not bend due to its own weight and does not come into contact with the top surface of the fixing unit 90 when the fixing transport unit 900 is slid. Therefore, the operability when the user slides the fixing transport unit 900 can be improved.

[0120] When replacing the intermediate transfer belt 60, rotate the cam lever 39 in the direction of arrow F, as shown in Figure 15(a). This operation causes the tension roller 63, which had been applying tension to the intermediate transfer belt 60, to move away from the inner surface of the intermediate transfer belt 60 in the direction of arrow G, and the tension applied to the intermediate transfer belt 260 is released by the force of a spring (not shown).

[0121] Next, the fixing heat exhaust duct 600, which is positioned and fixed to the front plate 811 and the rear plate 812 in the transfer belt unit 810, is removed. That is, screws b1 and b2 are removed, and the front positioning parts 600a and 600b are pulled out from the holes 811a and 811b. This exposes the entire outer surface of the intermediate transfer belt 60.

[0122] By integrating the fixed heat exhaust duct 600 and the double-turn upper guide 650, the amount of work required to remove fixing screws and parts can be reduced compared to when they are separate components. In other words, integrating the double-turn upper guide 650 and the fixed heat exhaust duct 600 minimizes the service technician's working time.

[0123] Finally, as shown in Figure 15(b), the intermediate transfer belt 60, which is now released and loosened, is removed from the transfer belt unit 810 in the direction of arrow H. Then, a new intermediate transfer belt 60 is installed using the reverse procedure described above, and the intermediate transfer belt 60 replacement process is completed.

[0124] (Configuration of the joint in the air supply duct) The intermediate transfer belt 60 can be removed by a service technician after they pull the intermediate transfer belt unit 800 forward relative to the image forming apparatus 500, as shown in Figure 13, in order to perform maintenance work such as replacement.

[0125] Figure 16 shows the relationship between the fixing heat exhaust duct 600 provided on the transfer belt unit 810 and the main duct 880 provided on the main frame of the image forming apparatus 500. Figure 16(a) is a cross-sectional view showing the intermediate transfer belt unit 800 mounted on the image forming apparatus 500 (Figure 12(a)). Figure 16(b) is a cross-sectional view showing the intermediate transfer belt unit 800 pulled out from the image forming apparatus 500 (Figure 13).

[0126] As shown in Figure 16(a), when the intermediate transfer belt unit 800 is attached to the image forming apparatus 100, the main body duct 880, which is supported by the rear side plate 570 of the main body frame, is connected to the fixing heat exhaust duct 600 of the intermediate transfer belt unit 800.

[0127] In this installed state, the fan 890 located inside the main duct 880 rotates, causing the air in the fixing heat exhaust duct 600 to be exhausted into the main duct 880 through the exhaust ports 603 and 604. In other words, the air drawn in through the intake ports 601 and 602 of the fixing heat exhaust duct 600 is discharged into the main duct 880.

[0128] On the other hand, when the intermediate transfer belt unit 800 is pulled out from the image forming apparatus 500 for maintenance work or the like, the heat dissipation duct 600 separates from the main duct 880, as shown in Figure 16(b). This is because, as described above, the heat dissipation duct 600 is fixed to the transfer belt unit 810.

[0129] Thus, since the fixed heat exhaust duct 600 and the main duct 880 are positioned opposite each other in the insertion / removal direction of the intermediate transfer belt unit 800 (arrow Y direction), they can be connected and separated as the intermediate transfer belt unit 800 is inserted or removed.

[0130] Furthermore, a sealing member 891 made of sponge material or the like is provided at the connection point between the main duct 880 and the exhaust ports 603 and 604 of the fuser heat exhaust duct 600. Therefore, not only is the heat shielding efficiency of the fuser heat exhaust duct 600 improved, but toner scattering and transport jams caused by air leaking out of the fuser heat exhaust duct 600 can be prevented, thus providing an image forming apparatus 10 with superior stability.

[0131] If the fixing heat exhaust duct 81 and the rear upper guide 85 were separate parts, it would increase the amount of work required to remove the screws securing each and to remove the parts. In other words, by integrating the rear upper guide 85 and the fixing heat exhaust duct 81 as in this embodiment, the time required for a service technician to replace the intermediate transfer belt 60 can be minimized.

[0132] In this embodiment, the fixed heat exhaust duct 600 may be fixed to the transfer cleaner unit 65, similar to the first embodiment. Alternatively, the second transfer upper guide 650 of the second embodiment may be integrally provided with the air supply duct 1 of the first embodiment. [Explanation of Symbols]

[0133] 71 Developing exhaust port 72 Pre-transfer charged exhaust port 73 Imaging cooling port 74 Electrostatic exhaust port 100 Image Forming Systems 101 Image forming apparatus 102 Image forming unit 103 Fixing and transport section 301 Fuser Unit 413 Pre-fixation transport intake fan 417 Fixing heat dissipation fan 418 Fixed pressurized intake fan 419 Fixed pressurized exhaust fan 420 Humidity Exhaust Fan 430 Front Exhaust Duct Unit 431 First constant pre-suction duct unit 431 Second Pre-Suction Duct Unit 432 First constant pre-suction duct unit 433 First constant suction duct junction 434 Second pre-suction duct junction 435 First constant pre-suction duct 436 Second pre-determined suction duct

Claims

1. Photoreceptor and A transfer unit comprising: a transfer belt onto which a toner image formed on a photoreceptor is transferred; a primary transfer roller facing the photoreceptor via the transfer belt and forming a primary transfer nip portion for primary transfer of the toner image formed on the photoreceptor to the transfer belt; a secondary transfer inner roller positioned below the primary transfer roller in the vertical direction and in contact with the inner circumferential surface of the transfer belt; a tension roller positioned between the secondary transfer inner roller and the primary transfer roller in the rotational direction of the transfer belt and tensioning the transfer belt; and a cleaning unit positioned downstream of the secondary transfer inner roller in the rotational direction of the transfer belt and cleaning the outer circumferential surface of the transfer belt. A secondary transfer outer roller, which faces the secondary transfer inner roller via the transfer belt and forms a secondary transfer nip portion for secondary transfer of the toner image formed on the transfer belt to the recording material, A support portion that supports the transfer unit so as to be movable along the rotation axis direction of the secondary transfer roller, Having an air intake port, and a blower duct provided in the transfer unit, The secondary transfer nip section is provided between the secondary transfer nip section and the cleaning unit in the transport direction of the recording material in the secondary transfer nip section, and includes a guide section for preventing the sheet from sticking to the transfer belt, The aforementioned air duct is provided integrally with the guide section, The air duct moves integrally with the transfer unit as the transfer unit moves relative to the support portion. An image forming apparatus characterized by the following features.

2. The image forming apparatus according to claim 1, characterized in that the air supply duct is fixed to the cleaning unit.

3. A transport means for transporting recording material downstream of the secondary transfer nip in the transport direction, on which a toner image has been transferred at the secondary transfer nip; A conveying unit having the conveying means and the secondary transfer outer roller, further comprising a conveying unit supported by the support portion so as to be movable along the rotation axis direction of the secondary transfer outer roller, The image forming apparatus according to feature 1 or 2.

4. The air duct is provided between the portion of the transfer belt that is stretched between the secondary transfer inner roller and the tension roller in the vertical direction and the conveying means. The image forming apparatus according to feature 3.

5. The air intake port is located outside the end of the transfer belt in the direction of the rotation axis of the secondary transfer inner roller. Image forming apparatus according to feature 4

6. The transport unit is further provided with fixing means for fixing a toner image onto the recording material transported by the transport means, The air duct is provided between the portion of the transfer belt that is stretched between the secondary transfer inner roller and the tension roller in the vertical direction and the fixing means. The image forming apparatus according to feature 3.

7. The fixing means includes a heating section, a first rotating body heated by the heating section, and a second rotating body that forms a fixing nip together with the first rotating body. The image forming apparatus according to claim 6, characterized in that the air intake is provided upstream of the fixing nip in the direction of transport of the recording material in the fixing nip.

8. The air supply duct has another air intake located downstream of the fixing nip in the direction of transporting the recording material in the fixing nip. The image forming apparatus according to feature 7.

9. The transfer unit is movable between a mounting position in which the secondary transfer nip portion is formed by the secondary transfer inner roller and the secondary transfer outer roller, and a pull-out position in which it is pulled forward of the image forming apparatus relative to the mounting position. The transfer unit has an operating lever that, when rotated while in the mounting position, moves the transfer belt away from the photoreceptor. The transfer unit is movable to the drawer position when the operating lever is rotated. The image forming apparatus according to any one of claims 6 to 8.

10. The aforementioned air supply duct has an exhaust port for exhausting the air drawn in from the intake port, The duct unit includes an intake port which is connected to the exhaust port when the transfer unit is in the mounting position and is separated from the exhaust port when the transfer unit is in the pull-out position, and a fan which forms an airflow inside the air supply duct when the transfer unit is in the mounting position. The image forming apparatus according to feature 9.

11. The photoreceptor, the transfer unit, and the first housing having the transport means, The second housing having the aforementioned fixing means further comprises In the transport direction of the recording material in the secondary transfer nip section, the transfer belt and the fixing means are provided, The aforementioned air supply duct has other air intake ports different from the aforementioned air intake port, The duct unit further comprises another duct unit having another exhaust port which is joined to the other intake port when the transfer unit is in the mounting position and separates from the other intake port when the transfer unit is in the withdrawal position. The image forming apparatus according to claim 9 or 10.

12. The air duct is located downstream of the secondary transfer nip section in the direction of transporting the recording material in the secondary transfer nip section, and is positioned vertically below the portion of the transfer belt that is stretched between the secondary transfer inner roller and the tension roller. The image forming apparatus according to any one of claims 1 to 11.

Images