JP2017134103A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus that can reduce the size of the image forming apparatus and effectively collect ultra fine particles generated in a fixing part.SOLUTION: An image forming apparatus 1 comprises: a fixing part 50 for fixing a toner to a sheet P; a curved part 42a in which a double-sided printing conveyance path 42 provided on the downstream side in a sheet conveyance direction of the fixing part 50 extends while being curved with respect to the conveyance direction; a duct 61 that has an intake port 61a opened therein, is arranged on the outside in the radial direction of the curved part 42a of the double-sided printing conveyance path 42, and extends in a sheet width direction intersecting with the sheet conveyance direction; and two fans 62F and 62B that are provided adjacent to the intake port 61a of the duct 61 to generate an airstream inside the duct 61 and arranged side by side in the sheet width direction, where the one on the intake side is directed to the fixing part 50.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an image forming apparatus represented by a copying machine.

  With the recent increase in global environmental protection awareness, ultra fine particles (hereinafter referred to as UFP) that are different from ozone and toner dust are generated from electrophotographic image forming apparatuses such as copying machines and printers. Has become a problem. UFP is a particle having a diameter of 100 nm or less.

  On the other hand, in an image forming apparatus, a thermal fixing method is widely adopted as a method for fixing an unfixed toner image transferred onto a sheet to the sheet. It has been found that UFP is mainly caused by a fixing member (roller or belt) for forming a fixing portion, more specifically, a nip portion for fixing. Further, UFP is more likely to occur as the temperature is higher, and the amount of UFP generated is greater in the non-image forming area (both ends in the paper width direction) of the fixing member that is likely to be relatively hot. Patent Document 1 discloses a conventional technique related to such UFP collection.

  The image forming apparatus described in Patent Document 1 includes a filter member disposed above both ends of the fixing member in the paper width direction, and a duct for guiding UFP generated in the fixing unit to the filter member. Thereby, this image forming apparatus can collect UFP by the filter member. Patent Document 2 discloses a fixing device in which fans are provided at both ends of the fixing roller in the paper width direction. The fans of the fixing device are air supply fans and are intended to cool the fixing roller. UFP cannot be collected.

JP 2011-186033 A JP 2013-186417 A

  In order to secure sufficient performance for collecting UFP, it has been a problem to provide a duct and a fan with a configuration that is more effective than the image forming apparatus described in Patent Document 1. And when there is one fan for generating an air current inside a duct, for example, it is necessary to install a comparatively large fan. For this reason, it is also desired to suppress the enlargement of the image forming apparatus due to the enlargement of the fan.

  The present invention has been made in view of the above points, and provides an image forming apparatus capable of downsizing an image forming apparatus and efficiently collecting UFP generated in a fixing unit. With the goal.

  In order to solve the above problems, an image forming apparatus of the present invention includes a fixing unit for fixing toner on a sheet, and a sheet conveyance path provided downstream of the fixing unit in the sheet conveyance direction with respect to the conveyance direction. A curved portion extending in the direction of the paper, a duct extending in the radial direction of the curved portion of the paper conveyance path with an intake port being opened and extending in the paper width direction intersecting the paper conveyance direction, and generating an air flow inside the duct In order to achieve this, there are provided two fans provided adjacent to the air inlet of the duct and arranged side by side in the paper width direction, and the air intake side faces the fixing portion.

  According to this configuration, since the two fans directed to the fixing unit are arranged side by side in the sheet width direction, air is discharged over the entire area of the fixing unit in the sheet width direction. Thereby, UFP generated in the fixing unit is effectively collected. Further, since the duct is arranged radially outside the curved portion of the paper conveyance path and extends in the paper width direction, a dead space that easily occurs on the radial outside of the curved portion of the paper conveyance path of the box-shaped main body housing is ducted. It is used for the arrangement of. Thereby, the enlargement of the image forming apparatus is suppressed.

  In the image forming apparatus having the above-described configuration, one surface of the intake side of the fan faces the curved portion of the sheet conveyance path.

  In the image forming apparatus having the above-described configuration, the duct has two air flow paths in which each of the two fans is individually arranged, and the two air flow paths are the diameters of the curved portions of the sheet conveyance path. It is characterized by being arranged adjacent to each other in the direction.

  In the image forming apparatus having the above-described configuration, each of the two fans is disposed corresponding to each of both ends of the fixing unit in the sheet width direction.

  In the image forming apparatus having the above-described configuration, a door portion that exposes the sheet conveyance path to the outside is provided, and the fan is provided in the door portion.

  Further, in the image forming apparatus having the above-described configuration, the door portion can be opened and closed by rotating around an axis of a substantially vertical support shaft portion, and the duct has two fans each having two fans individually disposed. A connecting portion that has an air flow path and is separated from and coming into contact with the opening and closing of the door portion is divided into two regions, and a confluence portion of the two air flow paths is a region closer to the door portion of the duct than the connection portion It is characterized by being arranged in.

  Further, in the image forming apparatus having the above configuration, a sheet conveyance path provided on the upstream side in the sheet conveyance direction of the fixing unit includes a vertical portion that is substantially perpendicular to the conveyance direction, and the curved portion of the sheet conveyance path is the fixing unit. The fan is disposed above the bending portion, and the fan is disposed above the bending portion.

  According to the configuration of the present invention, the air in the fixing unit can be effectively discharged by the two fans arranged side by side in the sheet width direction, and the duct is formed in a dead space that is likely to be generated radially outside the curved conveyance path. Can be arranged. Thereby, the image forming apparatus can be reduced in size, and an image forming apparatus capable of efficiently collecting UFP generated in the fixing unit can be provided.

1 is a partial vertical sectional front view of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a vertical sectional front view showing the periphery of the fixing unit of the image forming apparatus according to the embodiment of the present invention. FIG. 3 is an external perspective view of the exhaust unit above the fixing unit of the image forming apparatus according to the exemplary embodiment of the present invention when viewed from the inside. FIG. 3 is a partial side view of a vertical cross section of the exhaust unit above the fixing unit of the image forming apparatus according to the embodiment of the present invention as viewed from the inside. FIG. 3 is a front view illustrating a state in which a right side door portion of the main body housing of the image forming apparatus according to the embodiment of the present invention is opened. FIG. 3 is a partially enlarged front view illustrating a state in which a right side door portion of the main body housing of the image forming apparatus according to the embodiment of the present invention is opened. 3 is a partially enlarged top view showing a state in which a right side door portion of a main body housing of the image forming apparatus according to the embodiment of the present invention is opened. FIG. FIG. 5 is a vertical sectional side view of an image forming apparatus according to a second embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to the following contents.

  An image output operation of the image forming apparatus according to the embodiment of the present invention will be described while explaining the outline of the structure with reference to FIG. FIG. 1 is an example of a partial vertical sectional front view of an image forming apparatus. In the figure, a two-dot chain line with an arrow indicates a sheet conveyance path and a conveyance direction. In addition, the vertical direction, the horizontal direction, and the paper depth direction in FIG. 1 are the vertical direction, the horizontal direction, and the depth (front-back) direction of the image forming apparatus.

  As shown in FIG. 1, the image forming apparatus 1 is a so-called tandem type color copier, and an image reading unit 2 that reads an image of a document on a main body casing 1a, and prints the read image on a transfer material such as paper. A printing unit 3 that performs printing, an operation unit 4 for inputting printing conditions and displaying an operation status, and a main control unit 5.

  The image reading unit 2 is a known unit that reads an image of a document placed on the upper surface of a platen glass (not shown) by moving a scanner (not shown). An image of a document is separated into three colors of red (R), green (G), and blue (B), and is converted into an electrical signal by a CCD (Charge Coupled Device) image sensor (not shown). Accordingly, the image reading unit 2 obtains image data for each color of red (R), green (G), and blue (B).

  The image data for each color obtained by the image reading unit 2 is subjected to various processes in the main control unit 5, and image data for each reproduction color of yellow (Y), magenta (M), cyan (C), and black (K). And stored in a memory (not shown) inside the main control unit 5. The image data for each reproduction color stored in the memory is subjected to a process for correcting misregistration, and then is scanned for each scanning line in synchronism with the conveyance of the sheet in order to perform optical scanning on the photosensitive drum 21 which is an image carrier. Is read out.

  The printing unit 3 forms an image by an electrophotographic method, and transfers the image to a sheet or the like. The printing unit 3 includes an intermediate transfer belt 11 in which an intermediate transfer member is formed as an endless belt. The intermediate transfer belt 11 is wound around a driving roller 12 and driven rollers 13 and 14. A tension is applied to the intermediate transfer belt 11 by urging the driven roller 13 upward in FIG. 1 by a spring (not shown). The intermediate transfer belt 11 is rotated by the driving roller 12 counterclockwise in FIG.

  The driving roller 12 is pressed and brought into contact with the secondary transfer roller 15 facing the intermediate transfer belt 11. At the position of the driven roller 14, an intermediate transfer cleaning unit 16 provided so as to face the driven roller 14 with the intermediate transfer belt 11 interposed therebetween contacts the outer peripheral surface of the intermediate transfer belt 11. The intermediate transfer cleaning unit 16 scrapes and cleans toner remaining on the outer peripheral surface of the intermediate transfer belt 11 after the secondary transfer.

  Below the intermediate transfer belt 11, image forming units 20Y, 20M, 20C, and 20K corresponding to reproduction colors of yellow (Y), magenta (M), cyan (C), and black (K) are provided. In this description, the description of the identification symbols “Y”, “M”, “C”, and “K” is omitted unless it is particularly limited, and is generically referred to as “image forming unit 20”, for example. Sometimes. The four image forming units 20 are arranged in a line along the rotation direction of the intermediate transfer belt 11 from the upstream side to the downstream side in the rotation direction. The four image forming units 20 have the same configuration, and include a charging unit, an exposure unit, a developing unit, a cleaning unit, and a primary transfer roller around the photosensitive drum 21 that rotates clockwise in FIG. .

  Above the intermediate transfer belt 11, toner bottles 31 and toner hoppers 32 corresponding to the four image forming units 20 of the respective reproduction colors are provided. The developing unit and the toner hopper 32 are provided with a toner remaining amount detection unit (not shown) that detects the amount of toner inside each. Further, a toner replenishing device (not shown) is provided between the developing unit and the toner hopper 32 and between the toner hopper 32 and the toner bottle 31. When a decrease in the toner amount inside the developing unit is detected by the remaining amount detecting unit, the replenishing device is driven to replenish toner from the toner hopper 32 to the developing unit. Further, when the remaining amount detection unit detects a decrease in the toner amount inside the toner hopper 32, the replenishing device is driven to replenish the toner from the toner bottle 31 to the toner hopper 32. The toner bottle 31 is detachably provided to the main body housing 1a and can be replaced with a new one as appropriate.

  A sheet supply device 81 is provided below the four image forming units 20, and the sheet P is accommodated therein. The paper P accommodated in the paper supply device 81 is sent out one by one from the uppermost paper to the paper conveyance path 41 by the supply unit 82. The sheet conveyance path 41 includes a vertical portion 41b that is substantially perpendicular to the conveyance direction and is provided on the upstream side in the sheet conveyance direction (below the fixing unit 50) of the fixing unit 50 described later. The paper P sent out from the paper supply device 81 to the paper transport path 41 reaches the position of the registration roller pair 84. Then, the registration roller pair 84 corrects the skew feeding of the paper P (skew correction) and synchronizes with the rotation of the intermediate transfer belt 11 so as to contact the intermediate transfer belt 11 and the secondary transfer roller 15 (secondary transfer). The paper P is sent out toward the nip portion.

  In the image forming unit 20, an electrostatic latent image is formed on the surface of the photosensitive drum 21 by the charging unit and the exposure unit, and the electrostatic latent image is visualized as a toner image by the developing unit. The toner image formed on the surface of the photosensitive drum 21 is primarily transferred to the outer peripheral surface of the intermediate transfer belt 11 at a position where the photosensitive drum 21 faces the primary transfer roller with the intermediate transfer belt 11 interposed therebetween. The toner images of the image forming units 20 are sequentially transferred to the intermediate transfer belt 11 at a predetermined timing along with the rotation of the intermediate transfer belt 11, so that yellow, magenta, cyan, black on the outer peripheral surface of the intermediate transfer belt 11. A color toner image is formed by superimposing the four color toner images.

  The color toner image primarily transferred to the outer peripheral surface of the intermediate transfer belt 11 is formed by contacting the intermediate transfer belt 11 and the secondary transfer roller 15 on the paper P sent in synchronization by the registration roller pair 84. The secondary transfer nip is transferred.

  A fixing unit 50 is provided above the secondary transfer nip. The sheet P on which the unfixed toner image has been transferred at the secondary transfer nip is sent to the fixing unit 50 and is sandwiched between the fixing roller and the pressure roller, and the toner image is heated and pressurized to be melted and fixed on the sheet P. Is done. The paper P that has passed through the fixing unit 50 is discharged to a paper discharge unit 86 provided above the intermediate transfer belt 11.

  The operation unit 4 is provided on the front side of the image reading unit 2. The operation unit 4 inputs settings such as printing conditions such as the type and size of paper P used for printing by the user, enlargement / reduction, and presence / absence of double-sided printing, and settings such as a fax number and a sender name in facsimile transmission. Accept. The operation unit 4 also serves as a notifying unit for notifying the user of, for example, displaying the state of the device, precautions, and an error message on the display unit 4W.

  Further, the image forming apparatus 1 is provided with a main control unit 5 composed of a CPU (not shown), an image processing unit, and other electronic parts (not shown) for overall operation control. The main control unit 5 uses a central processing unit (CPU) and an image processing unit to control components such as the image reading unit 2 and the printing unit 3 on the basis of programs and data stored and input in a memory. Image forming operation and printing operation are realized.

  Next, a schematic configuration of the fixing unit 50 and its periphery will be described with reference to FIG. 2 in addition to FIG. FIG. 2 is a vertical sectional front view showing the periphery of the fixing unit 50. In the figure, a two-dot chain line with an arrow indicates a sheet conveyance path and a conveyance direction. 2 are the vertical direction, the horizontal direction, and the depth (front-rear) direction of the image forming apparatus 1 and the fixing unit 50, respectively.

  The fixing unit 50 includes a housing 51, a fixing roller 52, a pressure roller 53, and a heating source 54 as shown in FIG.

  The housing 51 covers the periphery of the fixing roller 52, the pressure roller 53, and the heating source 54, and further supports these components.

  The fixing roller 52 and the pressure roller 53 have a cylindrical shape, and are arranged side by side in the left-right direction so that the peripheral surfaces of the fixing roller 52 and the pressure roller 53 face each other with the paper transport path 41b interposed therebetween. The fixing roller 52 and the pressure roller 53 extend along the sheet width direction, ie, the front-rear direction of the image forming apparatus 1 and the fixing unit 50, which is the direction in which the rotation axes of the fixing roller 52 and the pressure roller 53 intersect the sheet conveying direction. The fixing roller 52 and the pressure roller 53 have a length corresponding to the entire area in the sheet width direction of the sheet conveyance path 41b. The fixing roller 52 and the pressure roller 53 are rotatably supported by a bearing portion (not shown) provided on the housing 51 at each rotation shaft.

  The fixing roller 52 has a laminated structure in which, for example, a heat insulating layer, an elastic layer, a heat generating layer, a release layer, and the like are provided in order in the radial direction toward the outer peripheral surface side on the outer side of the metal core provided at the rotation center. The surface of the fixing roller 52 generates heat by the action of the heating source 54 and heats the paper P on which the unfixed toner image is transferred to fix the toner on the paper P.

  The pressure roller 53 is given a predetermined pressure by a pressure mechanism (not shown) using a spring member or the like, and its peripheral surface is pressed against and in contact with the peripheral surface of the fixing roller 52 to form a fixing nip portion Nf. The pressure roller 53 obtains power from a drive source (not shown) and rotates clockwise in FIG. The fixing roller 52 rotates counterclockwise in FIG. 2 according to the rotation of the pressure roller 53 with which the peripheral surfaces come into contact with each other. The fixing roller 52 may be driven to rotate and the pressure roller 53 may be driven to rotate.

  The heat source 54 is disposed adjacent to the fixing roller 52 outside the fixing roller 52 in a region opposite to the side where the pressure roller 53 is disposed with respect to the fixing roller 52. The heating source 54 extends along the paper width direction in the same manner as the fixing roller 52. The heating source 54 includes, for example, an excitation coil (not shown), a magnetic core, a shield member, and the like, and includes an induction heating source that generates heat on the surface of the fixing roller 52 by induction heating. The temperature of the surface of the fixing roller 52 is detected by a temperature detection unit such as a thermistor (not shown), and the main control unit 5 controls the heating source 54 based on the temperature. Note that the configuration of the heating source 54 that generates heat on the surface of the fixing roller 52 is not limited to the induction heating source, and the surface of the fixing roller 52 may be heated using another configuration, such as a heater.

  A transport path switching unit 43 is provided on the downstream side of the fixing unit 50 in the paper transport direction and above the fixing unit 50. The transport path switching unit 43 includes a movable guide 43 a for switching the transport path of the paper P. The movable guide 43a can swing in a vertical plane around an axis of a rotation shaft (not shown) extending substantially horizontally in the paper width direction (front-rear direction of the image forming apparatus 1), and can change its posture.

  After fixing when the duplex printing is not performed and after fixing the second surface of the paper P when performing the duplex printing, the movable guide 43a changes its posture in a direction to send the paper P to the paper discharge unit 86. On the other hand, after fixing the first surface of the paper P in the case of performing double-sided printing, the movable guide 43a changes its posture in the direction in which the paper P is sent out to the double-sided printing conveyance path. As shown in FIG. 1, the duplex printing conveyance path 42 is disposed above and to the right of the sheet conveyance path 41, and is formed so that the sheet P circulates outside the fixing unit 50.

  Each of the sheet conveyance path 41 and the duplex printing conveyance path 42 includes curved portions 41 a and 42 a that are curved in the conveyance direction on the downstream side of the fixing unit 50 and above the fixing unit 50. The curved portion 41a of the paper transport path 41 and the curved portion 42a of the duplex printing transport path 42 are directed from the upper end side of the fixing unit 50 to the left in FIG. 2, that is, separated from the right side surface of the image forming apparatus 1 and directed inward. Bend. The downstream end of the curved portion 41 a of the paper transport path 41 in the paper transport direction reaches the paper discharge portion 86. An end portion in the sheet conveyance direction on the upper side of the curved portion 42 a of the duplex printing conveyance path 42 reaches a reverse tray 87 disposed above the sheet discharge portion 86.

  A reversing roller pair 44 is provided at a discharge port portion where the sheet P is discharged from the curved portion 42 a of the duplex printing conveyance path 42 toward the reversing tray 87. The reverse roller pair 44 performs forward rotation for sending the paper P toward the left in FIG. 2 toward the reverse tray 87 and reverse rotation for sending the paper P from the reverse tray 87 to the right in FIG. Can be switched.

  When performing double-sided printing, the paper P sent to the double-sided printing conveyance path 42 (curved portion 42a) toward the reverse tray 87 by the movable guide 43a after fixing the first surface of the paper P is transferred from the nip portion of the reverse roller pair 44. Before coming off, the reverse roller pair 44 switches its rotation from normal rotation to reverse rotation. Then, the sheet P, which has been directed downward along the curved portion 42a of the duplex printing conveyance path 42, is sent around the outside of the fixing section 50 by the movable guide 43a, and is more than the image forming section 20 of the sheet conveyance path 41. Guided downstream in the paper transport direction. Then, the toner image is formed, transferred, and fixed on the second surface of the paper P.

  An exhaust unit 60 is provided above the curved portion 42a of the duplex printing conveyance path 42 and outside the curved portion 42a in the radial direction. The exhaust unit 60 discharges air around the fixing unit 50, the curved portion 41 a of the paper conveyance path 41, and the curved portion 42 a of the duplex printing conveyance path 42 toward the outside of the image forming apparatus 1.

  Then, the structure of the exhaust part 60 is demonstrated using FIGS. 3-7 in addition to FIG. 3 and 4 are an external perspective view and a vertical sectional partial side view of the exhaust part 60 as seen from the inside. 5, 6, and 7 are a front view, a partially enlarged front view, and a partially enlarged top view showing a state in which the right side door portion of the main body housing is opened. In addition, the dashed-two dotted line with the arrow of FIG. 4 shows the flow path and flow direction of the airflow which generate | occur | produces in the exhaust part 60. FIG.

  As shown in FIG. 2, the exhaust unit 60 is disposed above the curved portion 42 a of the double-sided printing conveyance path 42 and outside the curved portion 42 a in the radial direction. That is, the exhaust unit 60 is provided in a space that forms a substantially triangular shape on the upper right side of the curved portion 42 a of the double-sided printing conveyance path 42 when the image forming apparatus 1 is viewed from the front. The exhaust unit 60 includes a duct 61 and two fans 62F and 62B as shown in FIGS.

  The duct 61 extends in the paper width direction, and an intake port 61a and an exhaust port (not shown) are opened to communicate them. The air inlet 61a faces the curved portion 42a of the duplex printing conveyance path 42 below the duct 61 and points in the direction in which the fixing unit 50 is located. The exhaust port is provided on the back surface of the main body housing 1a or in the vicinity of the back surface of the side surface.

  Here, the image forming apparatus 1 includes a right side door portion 6 shown in FIGS. 5 to 7 on the right side of the main body housing 1a. The right side door 6 forms the entire right side of the exterior of the main body housing 1a. The right side door portion 6 is supported by the main body housing 1a via a support shaft portion 6a provided in an end portion on the back side and extending substantially vertically. The right side door portion 6 rotates in the vertical plane around the axis of the support shaft portion 6a with the front end portion as a free end, and can be opened and closed with respect to the inside of the main body casing 1a. When the right side door portion 6 is opened, the duplex printing conveyance path 42 can be exposed to the outside (see FIGS. 3 and 6).

  The duct 61 is divided into two regions, a duct upstream portion 61U and a duct downstream portion 61L, by connecting portions 61c and 61d that are separated from each other as the right side door portion 6 is opened and closed (see FIGS. 5 to 7). A duct upstream portion 61U, which is a region upstream of the connecting portion 61c of the duct 61 in the air flow direction, is provided in the right side door portion 6. A duct downstream portion 61L, which is a region downstream of the connecting portion 61d of the duct 61 in the air flow direction, is provided inside the main body housing 1a. The connecting parts 61c and 61d are connected to each other by closing the right side door part 6, and leakage of air inside the duct 61 from this point can be prevented. The duct downstream portion 61L is provided with the above-described exhaust port, and a filter member (not shown) for collecting dust including UFP sucked from the intake port 61a is provided in the vicinity of the exhaust port.

  The upstream part 61U of the duct 61 has an upstream part in the air flow direction, and has a front upstream part 61F and a rear upstream part 61B, which are two air flow paths. The intake port 61a is provided at the upstream end of each of the front upstream portion 61F and the rear upstream portion 61B in the air flow direction. The intake port 61a of the front upstream portion 61F is disposed corresponding to the front end of the fixing unit 50 in the sheet width direction. The air inlet 61a of the rear upstream portion 61B is disposed corresponding to the rear end of the fixing unit 50 in the sheet width direction. A part of the front upstream portion 61F of the duct 61 and the rear upstream portion 61B are arranged adjacent to each other in the radial direction of the curved portion 42a of the double-sided printing conveyance path 42 and overlap inside and outside.

  The front upstream part 61F and the rear upstream part 61B join at a joining part 61e provided on the upstream side in the air flow direction of the connecting part 61c. The front upstream portion 61F extends from the front end of the fixing unit 50 in the sheet width direction toward the junction 61e. The rear upstream portion 61B extends from the end of the fixing portion 50 on the back side in the sheet width direction toward the merge portion 61e. That is, from the upstream side to the downstream side of the merging portion 61e, the air flow Wf generated inside the front upstream portion 61F and the air flow Wb generated inside the rear upstream portion 61B are both front sides in the sheet width direction of the fixing unit 50. It circulates from the back side.

  The fan 62F is provided inside the duct 61 adjacent to the air inlet 61a of the front upstream portion 61F of the duct 61. The fan 62B is provided inside the duct 61 adjacent to the air inlet 61a of the rear upstream portion 61B of the duct 61. The fans 62F and 62B are arranged side by side in the sheet width direction, and their intake side points in the direction in which the fixing unit 50 is located. Furthermore, the fans 62F and 62B have one surface on the intake side facing the curved portion 42a of the duplex printing conveyance path 42. The fans 62F and 62B are made of sirocco fans, for example, and generate airflows Wf and Wb inside the duct 61 (the front upstream portion 61F and the rear upstream portion 61B).

  As in the above-described embodiment, in the image forming apparatus 1, the fixing unit 50 for fixing toner on the paper P and the duplex printing conveyance path 42 provided on the downstream side of the fixing unit 50 in the paper conveyance direction are curved with respect to the conveyance direction. A curved portion 42a extending in the direction of the width of the double-sided printing conveyance path 42, the duct 61 extending in the paper width direction intersecting the paper conveyance direction, In order to generate an air flow inside, two fans 62 </ b> F and 62 </ b> B are provided adjacent to the air inlet 61 a of the duct 61 and arranged side by side in the paper width direction and the air intake side faces the fixing unit 50.

  According to this configuration, since the two fans 62F and 62B directed to the fixing unit 50 are arranged side by side in the sheet width direction, air can be discharged over the entire area of the fixing unit 50 in the sheet width direction. Thereby, it is possible to effectively collect UFP generated in the fixing unit 50. Further, since the duct 61 is disposed on the radially outer side of the curved portion 42a of the double-sided printing conveyance path 42 and extends in the paper width direction, the radial direction of the curved portion 42a of the double-sided printing conveyance path 42 of the box body 1a is formed. A dead space having a substantially triangular shape when viewed from the front which is likely to be generated on the outside can be used for the arrangement of the duct 61. Thereby, the enlargement of the image forming apparatus 1 can be suppressed. Therefore, the image forming apparatus 1 can be reduced in size, and UFP generated in the fixing unit 50 can be efficiently collected.

  Also, the fans 62F and 62B have one surface on the intake side facing the curved portion 42a of the duplex printing conveyance path 42.

  According to this configuration, one surface of the intake side of the fans 62F and 62B is directed in the direction in which the fixing unit 50 is disposed. Therefore, it is possible to collect UFP generated in the fixing unit 50 even more effectively.

  The duct 61 has a front upstream portion 61F and a rear upstream portion 61B, which are two air flow paths in which the two fans 62F and 62B are individually arranged. The front upstream portion 61F and the rear upstream portion 61B are arranged adjacent to each other in the radial direction of the curved portion 42a of the duplex printing conveyance path 42.

  According to this configuration, it is possible to arrange the front upstream part 61F and the rear upstream part 61B in which the two fans 62F and 62B are individually arranged by effectively using a small space. Therefore, the downsizing of the image forming apparatus 1 that can efficiently collect UFP generated in the fixing unit 50 can be improved. Further, from the upstream side to the downstream side of the junction 61e, the airflow Wf inside the front upstream portion 61F and the airflow Wb inside the rear upstream portion 61B are both from the front side to the back side in the sheet width direction of the fixing unit 50. Since it circulates in the direction, the pressure loss of the air volume at the junction 61e can be suppressed. Thereby, it is possible to effectively collect UFP generated in the fixing unit 50.

  Further, each of the two fans 62F and 62B is arranged corresponding to each of both ends of the fixing unit 50 in the sheet width direction.

  According to this configuration, each of the two fans 62F and 62B is arranged corresponding to the non-image forming area (both ends in the sheet width direction) of the fixing unit 50 where the amount of UFP generated is relatively large. it can. Therefore, it is possible to improve the action of collecting UFP generated in the fixing unit 50.

  In addition, the image forming apparatus 1 includes a right side door portion 6 that exposes the duplex printing conveyance path 42 to the outside, and two fans 62F and 62B are provided on the right side door portion 6.

  According to this configuration, when the right side door portion 6 is opened, the two fans 62F and 62B do not interfere with the visual recognition of the duplex printing conveyance path 42. Therefore, it is possible to easily perform jam processing and maintenance in the duplex printing conveyance path 42.

  Further, the right side door portion 6 can be opened and closed by rotating around a substantially vertical support shaft portion 6a, and the duct 61 has two air flow paths in which the two fans 62F and 62B are individually arranged. A front upstream portion 61F and a rear upstream portion 61B. Further, the duct 61 is divided into two regions, a duct upstream portion 61U and a duct downstream portion 61L, by connecting portions 61c and 61d that are separated from each other as the right side door portion 6 is opened and closed, and a front upstream portion 61F and a rear upstream portion 61B. The junction 61e is disposed in the duct upstream portion 61U, which is a region closer to the right side door portion 6 of the duct 61 than the connecting portion 61c.

  According to this configuration, since the merging portion 61e is disposed on the upstream side in the air flow direction with respect to the connecting portions 61c and 61d, the connecting portions 61c and 61d can have a simple configuration. Therefore, it is possible to easily connect the connecting portions 61c and 61d, and to prevent leakage of air inside the duct 61 including UFP from this portion. Further, if the connecting portions 61c and 61d are configured simply, it is possible to prevent the opening and closing operation of the right side door portion 6 from being hindered due to the connection of the connecting portions 61c and 61d.

  In addition, the sheet conveyance path 41 provided on the upstream side in the sheet conveyance direction of the fixing unit 50 includes a vertical portion 41 b that is substantially perpendicular to the conveyance direction, and the curved portion 41 a of the sheet conveyance path 41 is disposed above the fixing unit 50. Two fans 62F and 62B are disposed above the bending portion 41a.

  When the sheet conveyance path 41 includes the vertical portion 41b on the upstream side in the sheet conveyance direction of the fixing unit 50, a curved portion 41a is provided on the downstream side of the fixing unit 50 and above the curved portion 41a. In many cases, a dead space having a substantially triangular shape is formed on the outer side in the radial direction when viewed from the front. Therefore, according to the above configuration, the dead space can be effectively utilized by disposing the two fans 62F and 62B above the bending portion 41a. That is, the image forming apparatus 1 can be reduced in size, and UFP generated in the fixing unit 50 can be efficiently collected.

Second Embodiment
Next, an image forming apparatus according to a second embodiment of the present invention will be described with reference to FIG. FIG. 8 is an example of a vertical sectional side view of the image forming apparatus. In the figure, a two-dot chain line with an arrow indicates a sheet conveyance path and a conveyance direction. 8 are the vertical direction, the horizontal direction, and the depth (front-rear) direction of the image forming apparatus, and the right side of FIG. 8 is the front side of the image forming apparatus. This is the back side of the image forming apparatus. Since the basic configuration of this embodiment is the same as that of the first embodiment described above, the same components as those in the first embodiment are assigned the same names and reference numerals as before, and detailed descriptions thereof are given. May be omitted.

  An image forming apparatus 101 according to the second embodiment is a printer for monochrome printing as shown in FIG. 8, and has a printing unit 103 that prints an image on a transfer material such as paper on a main body housing 101 a, and input of printing conditions. And an operation unit 104 for displaying the operating status and a main control unit 105.

  The printing unit 103 includes a paper supply device 181, an image forming unit 120, and a fixing unit 150. The paper P stored in the paper supply device 181 is sent out one by one from the uppermost paper to the paper conveyance path 141 by the supply unit 182 in order. The toner image formed on the surface of the photosensitive drum 121 by the image forming unit 120 is transferred to the paper P transported through the paper transport path 141. The paper P on which the unfixed toner image has been transferred is sent to the fixing unit 150, where the toner image is heated and pressurized and melted and fixed on the paper P. The paper P that has passed through the fixing unit 150 is discharged to a paper discharge unit 186 provided on the upper surface of the main body housing 101a.

  The sheet conveyance path 141 is provided downstream of the fixing unit 150 in the sheet conveyance direction, and includes a curved portion 141 a that is curved with respect to the conveyance direction on the back side of the fixing unit 150. The curved portion 141 a of the paper conveyance path 141 is curved downstream in the paper conveyance direction of the fixing unit 150, that is, from the rear to the upper side of the fixing unit 150. The downstream side of the curved portion 141 a of the paper conveyance path 141 in the paper conveyance direction reaches the paper discharge portion 186.

  An exhaust unit 160 is provided behind the curved portion 141a of the paper conveyance path 141 and outside the curved portion 141a in the radial direction. That is, the exhaust unit 160 is provided in a space having a substantially triangular shape below the curved portion 141 a of the sheet conveyance path 141 when the image forming apparatus 101 is viewed from the side. The exhaust unit 160 discharges the air around the curved unit 141 a of the fixing unit 150 and the sheet conveyance path 141 toward the outside of the image forming apparatus 101.

  The exhaust unit 160 includes a duct 161 and two fans 162F and 162B. The duct 161 has an inlet port and an exhaust port that are opened to communicate with each other, and is disposed on the radially outer side of the curved portion 141a of the sheet conveyance path 141 and extends in the sheet width direction. The two fans 162 </ b> F and 162 </ b> B are provided adjacent to the air inlet of the duct 161 in order to generate an air flow inside the duct 161, arranged side by side in the paper width direction, and the air intake side faces the fixing unit 150.

  Although the first embodiment and the second embodiment have different configurations of the image forming apparatuses 1 and 101, similar operations and effects can be obtained.

  Although the embodiments of the present invention have been described above, the scope of the present invention is not limited to these embodiments, and various modifications can be made without departing from the spirit of the invention.

  For example, in the above-described embodiment, the image forming apparatus 1 is a so-called tandem color printing image forming apparatus that sequentially forms a plurality of color images using the intermediate transfer belt 11, but is limited to such a model. However, it may be an image forming apparatus for color printing that is not a tandem type.

  The present invention can be used in an image forming apparatus.

DESCRIPTION OF SYMBOLS 1,101 Image forming apparatus 1a, 101a Main body housing | casing 6 Right side door part 6a Support axis part 41, 141 Paper conveyance path 41a, 141a Bending part 41b Vertical part 42 Duplex printing conveyance path (paper conveyance path)
42a Curved part 50, 150 Fixing part 60, 160 Exhaust part 61, 161 Duct 61B Rear upstream part (air flow path)
61F Front upstream part (air flow path)
61L Duct downstream part 61U Duct upstream part 61a Inlet 61c, 61d Connecting part 61e Merging part 62B, 162B Fan 62F, 162F Fan

Claims (7)

A fixing unit for fixing toner on the paper;
A curved portion in which a paper conveyance path provided on the downstream side of the fixing portion in the paper conveyance direction is curved and extends with respect to the conveyance direction;
A duct having an inlet port opened and disposed radially outside the curved portion of the paper transport path and extending in the paper width direction intersecting the paper transport direction;
Two fans provided adjacent to the air inlet of the duct and arranged side by side in the paper width direction so as to generate an air flow inside the duct, and the air intake side is directed to the fixing unit;
An image forming apparatus comprising:   The image forming apparatus according to claim 1, wherein one surface of the intake side of the fan faces the curved portion of the sheet conveyance path.   The duct has two air circulation paths in which each of the two fans is individually arranged, and the two air circulation paths are arranged adjacent to each other in the radial direction of the curved portion of the sheet conveyance path. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus.   4. The image forming apparatus according to claim 1, wherein each of the two fans is disposed to correspond to both ends of the fixing unit in a sheet width direction. 5. A door for exposing the paper conveyance path to the outside;
The image forming apparatus according to claim 1, wherein the fan is provided in the door portion. The door portion can be opened and closed by rotating around the axis of the support shaft portion which is substantially vertical,
The duct has two air flow paths in which each of the two fans is individually arranged, and is divided into two regions by a connecting portion that comes into contact with and separates as the door portion opens and closes,
The image forming apparatus according to claim 5, wherein a merging portion of the two air flow paths is arranged in a region closer to the door portion of the duct than the connecting portion. A sheet conveyance path provided on the upstream side in the sheet conveyance direction of the fixing unit includes a vertical portion that is substantially perpendicular to the conveyance direction;
The image forming apparatus according to claim 1, wherein the curved portion of the sheet conveyance path is disposed above the fixing portion, and the fan is disposed above the curved portion. apparatus.