JP2004191550A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus that has an efficient layout through the solution of the problem related to a reduction in the installation space of the image forming apparatus, and enables a manual sheet feed tray and an inverse conveyance unit to be attached without increasing the installation space. <P>SOLUTION: The external body 6 of a document reading part placed on the top of the housing 5 of an apparatus main body projects outward at a side surface where a fixing unit in the housing 5 is proximately disposed. That is, since an empty space is created below the projecting external body 6, the heat of the fixing unit is efficiently radiated. By disposing the inverse conveyance unit 43 and the manual sheet feed tray 37 in the empty space, the installation space does not need to be increased. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image forming apparatus such as a copying machine and a facsimile machine.
[0002]
[Prior art]
Conventionally, in the above-described image forming apparatus, when the paper feed unit, the recording unit, and the paper discharge tray, which are the basic components, are arranged in a housing and laid out so as to include a document reading unit on the upper surface thereof There are many. That is, the recording operation of the paper is performed inside the housing, and the reading operation of the document is performed by the document reading device placed on the upper surface thereof. In such an image forming apparatus, when technical development is performed, reduction in installation space is always recognized as one problem.
[0003]
When the installation space is made compact inside the housing, the size of the paper in the paper feed unit and the paper discharge tray is the minimum required space. However, when the remaining space is to be reduced as much as possible, the paper feed unit It is necessary to form the transport path for transporting the sheet to the recording section-discharge tray as vertically as possible. Therefore, when the sheet transport path is formed in the vertical direction from the carry-out port of the sheet feeding unit, the sheet transport path is formed along the side frame of the housing. Therefore, the transfer unit and the fixing unit arranged along the sheet conveyance path in the recording unit are also arranged close to the side frame of the housing. When the fixing unit is arranged close to the side frame In order to efficiently dissipate the heat generated in the fixing unit, it is necessary to avoid contacting the side frame where the fixing unit is arranged close to the wall surface. However, the necessity of providing a space between the wall and the wall increases the installation space and hinders compactness.
[0004]
On the other hand, the original reading device mounted on the upper surface of the housing often includes an automatic document reading device (ADF) and an original mounting table (flat bed) for copying a book or the like. In addition to the space described above, a space for the automatic document reading unit is required. Therefore, for example, when the size of the recording paper is a maximum of A3 size, the size of the document placing table is larger than A3 size, and the size of the document reading device needs to include a document automatic reading device portion in the longitudinal direction thereof. Become.
[0005]
Therefore, as the housing installation space is reduced in size, it approaches the maximum size of usable paper.However, the document reading device requires space for the document mounting table and the document automatic reading device. The size of the document reading device is one of the factors that determine the installation space of the image forming apparatus. Therefore, for example, as shown in Patent Literature 1, a part of the document reading device is arranged so as to protrude from the side surface of the housing.
[0006]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 9-68835
[Problems to be solved by the invention]
In view of the above, the present invention solves the problems associated with the compact installation space as described above, provides an efficient layout, and enables the manual paper feed tray and the reverse transport unit to be mounted without increasing the installation space. It is an object to provide a forming apparatus.
[0008]
[Means for Solving the Problems]
The image forming apparatus according to the present invention is configured such that, in a housing in which a paper supply unit, a recording unit, and a paper discharge tray are arranged at predetermined positions, a sheet carried in from the paper supply unit is transported to the recording unit, and the paper discharge tray The image forming apparatus further includes a sheet conveying unit for unloading the document, and an image reading unit including a document mounting table that reads the document in a stationary state. The fixing unit of the recording unit is arranged, and the exterior body of the image reading unit has a projecting portion projecting at least in the horizontal direction at a side frame portion where the fixing unit is arranged in proximity. Furthermore, a manual paper feed tray is provided on the side frame portion so as to be freely opened and closed. Further, the outermost position where the manual sheet feed tray projects in the horizontal direction from the side frame portion in the open state is set inside the outermost position in the horizontal direction of the projecting portion. I do. Further, a reversing conveyance unit is mounted on the side frame portion. Further, an outermost position where the reverse transport unit projects horizontally from the side frame portion is set inside an outermost position in the horizontal direction of the projecting portion.
[0009]
With the above configuration, it is possible to use the installation space of the protruding portion, in which the exterior body of the image reading unit projects horizontally from the side frame of the housing, as the heat radiation space of the fixing unit. The heat radiation space of the fixing unit can be secured without increasing the installation space. In other words, the size of the image reading unit is a major factor in determining the installation space of the image forming apparatus due to the reduction of the installation space of the housing part. It is possible to suppress an increase in the installation space by overlapping with the space generated by the projecting portion.
[0010]
Further, by arranging an auxiliary device such as a manual paper feed tray or a reversing transport unit in a space generated by the protrusion of the exterior body of the image reading unit, it is possible to suppress an increase in installation space due to mounting of the auxiliary device. That is, by setting the outermost position where the manual paper feed tray projects in the horizontal direction from the side frame in the open state, inside the outermost position in the horizontal direction of the protrusion of the exterior body of the image reading unit, The manual paper feed tray can be mounted without increasing the entire installation space. For example, when a person or the like passes by the side of the manual sheet feed tray in an open state, the passage of the image reading unit is restricted by the protrusion of the exterior body of the image reading unit, thereby avoiding contact with the manual sheet feed tray. Can be. Similarly, in the case of the reverse transport unit, by setting the outermost position projecting horizontally from the side frame to the inside of the horizontal outermost position of the projecting portion of the exterior body of the image reading unit. In addition, it is possible to mount the reversing transport unit without increasing the entire installation space, and it is possible to avoid contact caused by traffic of a person or the like.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments according to the present invention will be described in detail. FIG. 1 is a schematic sectional view of the entire image forming apparatus according to the present invention. FIG. 2 is a schematic cross-sectional view illustrating a state in which the reverse conveyance unit is mounted on the image forming apparatus. A document reading unit 2 is disposed above the image forming apparatus 1, and a sheet feeding unit 3 and a recording unit 4 are disposed below the image reading unit 2 from the bottom.
[0012]
In the document reading unit 2, a document placed on a document tray 11 provided on a document cover 10 is conveyed to a position facing the reading unit by a document conveying device 12 to perform a document reading operation. Is discharged. When reading a book or the like, the document cover 10 is opened upward, a reading portion of the book or the like is arranged on the flatbed platen 14, and a reading operation is performed by reading means. The above configuration is the same as that of a conventional document reading apparatus having a so-called ADF type and flatbed type.
[0013]
In the paper feed unit 3, paper feed cassettes 15 and 16 are arranged in upper and lower tiers, and a plurality of sheets of a predetermined size are stacked on flappers 17 and 18, respectively. The right ends of the flappers 17 and 18 are pivotally supported by hinges in the figure, and pickup rollers 19 and 20 are disposed on the left side. The flappers 17 and 18 are urged upward so that the upper surfaces of the stacked sheets come into contact with the pickup rollers 19 and 20. When the pickup roller 19 or 20 is driven to rotate in this state, the sheets are fed one by one to the sheet transport path by the frictional force.
[0014]
The fed paper is conveyed to the recording unit 4 by the feed roller 21 and the press roller 22. The recording unit 4 includes a toner container 23, a memory removing brush 24, a charging charger 25, a photosensitive drum 26, a transfer roller 27, an exposure head 28, and a fixing roller 29 for recording an image on a conveyed sheet. I have. First, the surface of the photosensitive drum 26 is uniformly charged by using the charging charger 25, and the charged photosensitive drum 26 is exposed by the exposure head 28 in accordance with an image recording signal to form an electrostatic latent image. . Next, the toner in the toner container 23 is transferred from the supply roller 30 to the electrostatic latent image formed on the photosensitive drum 26 via the developing roller 31 to be visualized, and is transferred to the surface of the photosensitive drum 26 by the transfer roller 27. Is transferred to a sheet. Then, the transferred toner image is nipped by the fixing roller 29 and the press roller 32, heated and pressed, and fixed on the sheet. The fixed sheet is conveyed to a sheet discharge tray 35 while being sandwiched between a discharge roller 33 and a press roller 34.
[0015]
In FIG. 1, the area from the paper feed unit 3 to the paper discharge tray 35 is indicated by a dashed line and is a paper transport path. Further, a paper trailing edge detection sensor 36 is provided upstream of the discharge roller 33.
[0016]
On the other hand, a storage opening 38 is provided on the side surface of the image forming apparatus 1 so as not to be detachable, and a manual paper feed tray 37 is provided in the storage opening 38. In FIG. 1, the manual paper feed tray 37 is locked by a locking member (not shown) on the apparatus main body and is in the closed position. However, the manual paper feed tray 37 is pivotally supported by the rotation shaft 39 and rotates to the open position. A pickup roller 40 for transporting manually-fed paper and a pad 41 pressed against the paper are provided below the storage opening 38. The rotation of the pickup roller 40 allows the manually fed paper to be supplied. The paper is then transported along the guide 42 between the feed roller 21 and the press roller 22.
[0017]
In FIG. 2, the manual feed tray 37 is rotated outward about the rotation shaft 39 and is at an open position separated from the storage opening 38. The reversing transport unit 43 is mounted above the manual paper feed tray 37. A projecting portion 44 is formed at the lower portion of the reversing transport unit 43 so as to be inserted into the storage opening 38, and a driving mechanism such as a motor described later is inserted into the apparatus main body at the upper portion. A claw portion (not shown) is formed on the bottom surface 45 of the protruding portion 44 of the reverse transport unit 43 so that the hook portion can be hooked and attached to a support base 46 provided in the image forming apparatus main body. When the reverse transport unit 43 is mounted on the apparatus main body, the protruding portion 44 protrudes more toward the apparatus main body than the surface of the reverse transport unit 43 that contacts the outermost surface of the apparatus main body.
[0018]
A reverse transport path 47 is formed in the reverse transport unit 43 in a substantially U-shape. A feed roller 48 and a press roller 49 are provided on the upper inclined transport path, and a feed roller 50 is provided on the lower inclined transport path. And a press roller 51, respectively, and the sheet is reversely conveyed by the two sets of conveying rollers. Further, at least a part of the feed roller 50 and the press roller 51 is disposed in the protrusion 44 so as to be located in a space in the storage opening 38.
[0019]
A reversing carry-out path is formed in the apparatus main body from the discharge roller 33 to the paper carry-out port 53 along the guide 52, and the storage opening 38 has a paper carry-in port 54 above the manual feed port. , A reversing carry-in path is formed along the guide 55 to the feed roller 21. Therefore, when the reverse transport unit 43 is mounted, the reverse transport path, the reverse transport path 47, and the reverse transport path are connected to form a transport path as shown by a dashed line in FIG.
[0020]
In the case of performing the reverse conveyance control of the sheet, the sheet on which the image is formed on one side is driven once by driving the discharge roller 33 toward the discharge tray 35, and the sheet rear end detection sensor 36 detects the rear end of the sheet. At this point, the discharging operation is stopped. At this point, the rear end of the sheet is held between the discharge roller 33 and the press roller 34. Thereafter, as described later, the motor in the reversing conveyance unit 43 is driven to rotate the discharge roller 33 so as to reversely convey the sheet, and conveys the sheet from the rear end of the sheet to the sheet discharge port 53 through the reversing discharge path. The feed roller 48 and the feed roller 50 rotate in conjunction therewith, and the sheet is conveyed through the reversing conveyance path 47, is conveyed from the sheet carry-in port 54 to the reversing conveyance path, and is again hit against the feed roller 21. Thereafter, an image is formed on the remaining surface (back surface) by the recording unit 4, and image formation control on both surfaces is performed.
[0021]
A paper guide port 56 for performing manual paper feed is formed between the manual paper feed tray 37 and the opposing surface 57 of the reverse transport unit 43. By forming the paper guide opening 56, both the manual paper feed operation and the reverse conveyance operation can be performed without removing the manual paper feed tray 37 from the apparatus main body. Further, since the paper guide port 56 can be visually recognized even from diagonally above, the paper can be easily guided to the paper feed port. On the upper surface of the manual paper feed tray 37, a side guide 58 for positioning the paper is provided. If the paper is slid and positioned in accordance with the size of the paper, the manual paper feed can be accurately performed. .
[0022]
In the image forming apparatus 1, a paper conveyance path in the apparatus main body is formed vertically upward from the paper supply unit 3, and is connected to an upper discharge tray 35. By forming the paper transport path in this way, the transport path can be shortened, and the apparatus body can be made compact. Therefore, the photosensitive drum 26, the transfer roller 27, and the fixing roller 29 of the recording unit 4 are also arranged in the vertical direction along the sheet transport path, and are laid out on one side of the apparatus main body (the left side in the examples of FIGS. 1 and 2). You. With such a layout, the installation space of the apparatus main body can be made close to the size of the paper loaded on the paper feed unit 3, and the apparatus main body can be made compact. On the other hand, in the document reading unit 2, the document feeder (ADF) 12 is laid out on the left side of the flat bed 14, so that the width in the left-right direction is compared with the width in the left-right direction as shown in FIG. 3 and the housing 5 in which the recording unit 4 is arranged.
[0023]
Conventionally, in order to hide such a difference in width in design, the width of the housing 5 is set to be the same as the width of the document reading unit 2. In this embodiment, however, the side surface of the housing 5 in which the fixing roller 29 is disposed in close proximity. The layout is such that the exterior body 6 of the document reading section 2 projects toward the frame portion. With such a layout, even if the fixing roller 29 generates heat, a gap is secured on the outer surface of the adjacent side frame portion, so that heat can be efficiently radiated. In this way, if the exterior body 6 of the document reading unit 2 does not protrude, the side frame portion where the fixing roller 29 is disposed in close proximity may be installed in close contact with the wall surface. Although there is a possibility that it becomes worse and causes a failure, such a situation can be avoided in this embodiment.
[0024]
As shown in FIG. 2, the outermost position in the horizontal direction from the side frame portion mounted when the reverse transport unit 43 is mounted is located inside the protruding portion of the exterior body 6 of the document reading unit 2. Is set to That is, the outermost position of the reversing transport unit is set to be inside by a distance m with respect to a vertical plane passing through the outermost position of the protruding portion of the exterior body 6. With such a setting, the space generated by the projecting portion of the exterior body 6 can be effectively used. Further, when the image forming apparatus is installed so as to provide a passage for a person on the side surface on which the reversing / conveying unit 43 is mounted, the protruding portion of the exterior body 6 restricts the passage of a person, and It can prevent contact with people passing by. Conversely, since the protruding portion of the exterior body 6 is conscious, even if the reverse transport unit 43 is mounted, it does not obstruct the passage of people.
[0025]
In addition, the outermost position of the manual paper feed tray 37 in the open position is set inward by a distance n with respect to a vertical plane passing through the outermost position of the protruding portion of the exterior body 6. With this setting, it is possible to effectively use the space generated by the projecting portion of the exterior body 6 and prevent contact when a person passes as in the case of the reverse transport unit 43.
[0026]
FIG. 3 is a perspective view of the reverse transport unit 43 as viewed from the inside, and FIG. 4 is a schematic view of the drive mechanism as viewed from the side.
[0027]
As shown in FIG. 3, the main body frame 100 includes left and right side frames 101 and a lower frame 102, a rear frame 103, and an upper frame 104 integrally formed therebetween in this order from the bottom. Inside, side guides 105 and 106 are fixed substantially parallel to the side frame 101 along the reverse conveyance path. A main body support plate 107 is provided on the inner surface of the upper frame 104, and holes 108 and 109 for fixing the reversing conveyance unit to the apparatus main body with screws or the like are formed in the main body support plate 107. . The side guides 105 and 106 have a shape curved toward the rear frame 103 along the reverse conveyance path 47. Along the curved shape, an outer guide 110 and an inner guide 111 are mounted between the side guides 105 and 106 so as to be parallel to each other at a predetermined interval. The inner guide 111 is a guide closer to the apparatus main body, and the outer guide 110 is a guide closer to the main body frame 100. A reversing conveyance path 47 is formed in a region surrounded by the four guides of the side guides 105 and 106, the outer guide 110, and the inner guide 111, and the paper inlet 112 connected to the paper outlet 53 of the apparatus main body and the paper loading port 47. An outlet 113 connected to the port 54 is formed.
[0028]
The feed roller 48 and the press roller 49, and the feed roller 50 and the press roller 51 are arranged in the reverse conveyance path 47 as described above. The feed roller 48 is fixed to a roller shaft 116, and the roller shaft 116 is rotatably held between the side guides 105 and 106. The press roller 49 is fixed to a roller shaft 117, and the roller shaft 117 is rotatably held by an inner guide 111. The press roller 49 presses the feed roller 48 at the openings 114 and 115 provided in the inner guide 111. The feed roller 50 is fixed to a roller shaft 119, and the roller shaft 119 is rotatably held between the side guides 105 and 106. The press roller 51 is fixed to a roller shaft 118, and the roller shaft 118 is rotatably held by an inner guide 111. The press roller 49 is pressed against the feed roller 48 at the openings 120 and 121 provided in the inner guide 111.
[0029]
A gear support plate 123 to which a motor 122 and a gear mechanism for driving the feed rollers 48 and 50 are attached is fixed between the side frame 101 and the side guide 106. A hole is formed in the gear support plate 123, and the motor 122 is mounted with the motor shaft protruding from the hole. A part of the motor 122 protrudes outward from the end surface of the side frame 101, and a cover member 124 is mounted along the end surface of the side frame 101 so as to cover the protruding portion.
[0030]
FIG. 4 is a side view of the reverse transport unit 43 as viewed from the side frame 101. To facilitate understanding of the gear mechanism, the side frame 101, the motor 122, and the gear support plate 123 are drawn by dashed lines. The motor shaft 125 of the motor 122 projects from the hole of the support plate 123 as described above, and is arranged on the opposite side of the support plate 123 from the motor 122. A drive gear 126 is fixed to the motor shaft 125, and a two-stage reduction gear 127 meshes with the drive gear 126. The two-stage reduction gear 127 is rotatably attached to the gear support plate 123 and includes a large-diameter portion gear portion 128 and a small-diameter portion gear portion 129. The large-diameter portion 127 meshes with the drive gear 126. .
[0031]
The first transmission gear 130 meshes with the small-diameter portion 129, and the second transmission gear 131 and the third transmission gear 132 mesh with the first transmission gear 130 sequentially. As shown in FIG. 4, it is rotatably attached to the plate 123 and projects outward from the end face of the side frame 101 as going from the first transmission gear 130 to the third transmission gear 132 (in FIG. 4, Left direction). By projecting outwardly, the drive transmission mechanism in the apparatus main body and the third transmission gear 132 mesh with each other as described later when mounted on the image forming apparatus, and the driving force of the motor 122 is transmitted. You.
[0032]
A roller driving gear 133 is separately meshed with the small diameter portion 129, and the roller driving gear 133 is fixed to the roller shaft 116 to which the feed roller 48 is attached. A pulley 134 protrudes from the roller drive gear 133 on the side guide 106 side, and a pulley 135 having the same diameter is also fixed to a roller shaft 119 to which the feed roller 50 is attached. An endless belt 136 is suspended between the pulley 134 and the pulley 135.
[0033]
When the motor 122 drives and the motor shaft 125 rotates, the drive gear 126 rotates and the two-stage reduction gear 127 rotates. Therefore, the rotation of the small diameter portion 129 is transmitted from the first transmission gear 130 to the roller drive gear 133, and the feed roller 48 rotates. At the same time, since the pulley 134 also rotates, the pulley 135 rotates via the endless belt 136, and the feed roller 50 rotates. In this manner, the sheet is reversed and conveyed by the rotation of the feed rollers 48 and 50.
[0034]
The motor 122 has two mounting plate portions 138 extending at symmetrical positions on both sides about the motor shaft 125, and the motor 122 is fixed to the gear support plate 123 by a fixing member 139 at each of the mounting plate portions 138. . The gear support plate 123 is fixed by a mounting member (not shown) on the rear frame 103. In a fixed state of the gear support plate 123, a part 137 of the motor 122 is connected to the inner end surface of the side frame 101 (the left end surface in FIG. 4). ) Protruding outward.
[0035]
FIG. 5 is a schematic partial cross-sectional view showing a state in which the reverse transport unit 43 is mounted on the apparatus main body, and FIG. 6 is an external perspective view thereof. In the reversing transport unit 43, a drive transmission mechanism such as a motor 122 protruding outward and a third transmission gear 132 attached to a gear support plate 123 is inserted into the apparatus main body at an upper part thereof, and a projecting part 44 is formed at a lower part thereof. Is inserted into the storage opening 38 of the apparatus main body.
[0036]
In the main body frame 100 of the reversing conveyance unit 43, a housing portion 140 for housing the manual paper feed tray 37 is formed in the lower frame 102 and the rear frame 103. As shown in FIG. 6, the storage section 140 is formed in a concave shape so as to be cut out with the same width as the width of the manual paper feed tray 37, and both sides thereof are substantially parallel to the side frame 101. On both sides thereof, engagement projections 141 are provided, respectively. As shown in FIG. 5, an extension plate 143 is slidably provided inside the manual paper feed tray 37, and a handle 144 is provided at an upper portion. When the manual paper feed tray 37 rotates around the rotation shaft 39 and is housed in the housing portion 140, the engagement recesses 142 formed on both sides of the manual paper feed tray 37 are fitted, and It is held in the unit 140.
[0037]
FIG. 7 is a schematic external view of the reversing transport unit 43 as viewed from the rear side in a state where the manual feed tray 37 is stored in the storage unit 140. Engagement concave portions 142 provided on both sides of the manual paper feed tray 37 are fitted and held by engagement convex portions 141 provided on both sides of the housing portion 140. As a method for holding the manual paper feed tray 37, as shown in FIG. 8, an engagement convex part 141 is provided on the upper part of the accommodation part 140, and an engagement concave part 142 is provided on the upper part of the manual paper feed tray 37 for holding. It may be. As long as the manual paper feed tray 37 can be held in the storage section 140, other methods can be adopted, and there is no particular limitation.
[0038]
Further, if the central portions of the rear frame 103 and the lower frame 102 of the reverse transport unit 43 can be opened and closed about the rotation shaft 146 as a cover 145, the paper jam in the reverse transport path 47 can be easily performed. Becomes possible. When the cover portion 145 is opened, the rotation shaft 39 of the manual paper feed tray 37 and the rotation shaft 146 of the cover member 145 are located at positions shifted from each other. The portion 141 and the engagement recess 142 are automatically separated from each other, and the manual feed tray 37 is also opened.
[0039]
In the embodiment described above, the holding unit for holding the manual paper feed tray 37 is provided in the reversing conveyance unit 43 so that the manual paper feed tray 37 is inverted from the maximum open position (the open position as shown in FIG. 2). Although the holding unit is held on the transport unit 43 side, such holding means may be provided on the apparatus main body side. For example, as shown in FIG. 10, an engagement protrusion 147 is provided to project from an intermediate portion of the manual paper feed tray 37, and a protrusion 148 provided with an engagement recess to be engaged with the engagement protrusion 147 is provided on the apparatus main body. Alternatively, the manual paper feed tray 37 may be held by the protrusion 148. As shown in FIG. 11, an engagement protrusion 151 is formed on the apparatus main body side from the rotation shaft 39 of the manual paper feed tray 37, and a curved portion 152 that engages with the engagement protrusion 151 is formed on the frame of the apparatus main body. The formed leaf spring 149 may be fixed by the screw 150, and the manual paper feed tray 37 may be held by the curved portion 152 of the leaf spring 149. As shown in FIG. 12, an engagement protrusion 151 is protruded at an intermediate portion of the manual paper feed tray 37, and an engagement protrusion 152 is also protruded from the apparatus main body. When the spring 153 is locked, the manual paper feed tray 37 can be rotated to hold the manual paper feed tray 37 at a position where the spring 153 has moved upward and below the rotation shaft 39.
[0040]
As shown in FIG. 13, an opening 154 for insertion is provided at a portion of the apparatus main body where the gear support plate 123 to which the motor 122 and the third transmission gear 132 and the like are inserted above the reversing conveyance unit 43. A cover plate 155 is attached to the opening 154 with screws. Therefore, when the reverse transport unit 43 is not mounted, the opening 154 is closed, so that intrusion of dust and the like can be prevented. As a method of closing the opening 154, as shown in FIG. 14, in addition to the screw, as shown in FIG. 14, the connection 157 formed so thin that the periphery of the cover plate 155 can be cut is integrally formed with the opening 154. Is also good.
[0041]
When the reverse conveyance unit 43 is mounted, the third transmission gear 132 meshes with the gear 160 attached to the roller shaft 158 of the discharge roller 33 as shown in FIG. The gear 160 is attached to the roller shaft 158 via the one-way clutch 163, and the one-way clutch 163 is connected to the clutch and transmitted to the roller shaft 158 only when the motor 122 rotates. Another gear 159 is attached to the roller shaft 158, and the driving force of a motor 161 that rotationally drives a transport roller in the apparatus main body is transmitted to the gear 159. The gear 159 is attached to the roller shaft 158 via the one-way clutch 162, and the one-way clutch 162 is connected to the clutch and transmitted to the roller shaft 158 only when the motor 161 rotates. Therefore, when the motor 161 is driven to rotate, the gear 159 is connected to the clutch, the roller shaft 158 rotates, the discharge roller 33 rotates, and the paper is discharged to the discharge tray 35. At this time, the one-way clutch 163 is not connected and has no effect on the rotation operation of the roller shaft 158.
[0042]
On the other hand, when the motor 122 rotates, the rotation drive is transmitted from the third transmission gear 132 to the gear 160. In this case, the motor 161 is driven to rotate in a direction opposite to that when the motor 161 rotates, the clutch of the gear 160 is connected, and the roller shaft 158 rotates in the direction opposite to when the sheet is discharged. Then, the discharge roller 33 conveys the sheet to the sheet outlet 53. At this time, the one-way clutch 162 is not connected, and does not affect the rotation operation of the roller shaft 158. As described above, by setting the clutches to be engaged when the gears 159 and 160 are rotated in directions opposite to each other, the sheet discharge operation of the discharge roller 33 and the reverse conveyance operation can be switched appropriately and operated.
[0043]
【The invention's effect】
As described above, in the present invention, it is possible to use the installation space of the projecting portion in which the exterior body of the image reading unit projects horizontally from the side frame of the housing as the heat radiation space of the fixing unit. The heat radiation space of the fixing unit can be secured without increasing the installation space. In other words, the size of the image reading unit is a major factor in determining the installation space of the image forming apparatus due to the reduction of the installation space of the housing part. It is possible to suppress an increase in the installation space by overlapping with the space generated by the projecting portion.
[0044]
Further, by arranging an auxiliary device such as a manual paper feed tray or a reversing transport unit in a space generated by the protrusion of the exterior body of the image reading unit, it is possible to suppress an increase in installation space due to mounting of the auxiliary device. That is, by setting the outermost position where the manual paper feed tray projects in the horizontal direction from the side frame in the open state, inside the outermost position in the horizontal direction of the protrusion of the exterior body of the image reading unit, The manual paper feed tray can be mounted without increasing the entire installation space. For example, when a person or the like passes by the side of the manual sheet feed tray in an open state, the passage of the image reading unit is restricted by the protrusion of the exterior body of the image reading unit, thereby avoiding contact with the manual sheet feed tray. Can be. Similarly, in the case of the reverse transport unit, by setting the outermost position projecting horizontally from the side frame to the inside of the horizontal outermost position of the projecting portion of the exterior body of the image reading unit. In addition, it is possible to mount the reversing transport unit without increasing the entire installation space, and it is possible to avoid contact caused by traffic of a person or the like.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view of an entire image forming apparatus without a reversing conveyance unit.
FIG. 2 is a schematic cross-sectional view of the entire image forming apparatus in a state where a reverse conveyance unit is mounted.
FIG. 3 is a perspective view of a reverse transport unit.
FIG. 4 is a schematic cross-sectional view of the reverse transport unit as viewed from a side.
FIG. 5 is a schematic partial cross-sectional view showing a state in which the reverse transport unit is mounted.
FIG. 6 is a schematic perspective view showing a state in which the reverse transport unit is mounted.
FIG. 7 is an explanatory diagram of a state in which a manual sheet feeding tray is accommodated in a reverse conveyance unit.
FIG. 8 is an explanatory diagram of another example of a state in which the manual paper feed tray is housed in the reverse conveyance unit.
FIG. 9 is an explanatory diagram when the cover member of the reverse transport unit is opened.
FIG. 10 is an explanatory diagram of an example in which a manual paper feed tray is held in the apparatus main body.
FIG. 11 is an explanatory diagram of another example of holding a manual paper feed tray in the apparatus main body.
FIG. 12 is an explanatory diagram of another example of holding a manual sheet feeding tray in the apparatus main body.
FIG. 13 is an explanatory diagram when the upper portion of the reverse transport unit is inserted into the apparatus main body.
FIG. 14 is an explanatory diagram of another example when inserting the upper portion of the reverse transport unit into the apparatus main body.
FIG. 15 is an explanatory diagram of a paper transport drive mechanism when the reverse transport unit is mounted.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 image forming apparatus 2 document reading unit 3 paper feeding unit 4 recording unit 5 housing 6 exterior body 33 discharge roller 34 press roller 35 discharge tray 36 paper trailing edge detection sensor 37 manual paper feed tray 38 storage opening 39 rotation shaft 40 Pickup roller 41 Pad 42 Guide 43 Reverse transport unit 44 Projecting portion 45 Bottom surface 46 Support base 47 Reverse transport path 48 Feed roller 49 Press roller 50 Feed roller 51 Press roller 52 Guide 53 Paper carry-out port 54 Paper carry-in port 55 Guide 56 Paper guide port 57 Opposing surface 58 Side guide 100 Main frame 101 Side frame 102 Lower frame 103 Back frame 104 Upper frame 105 Side guide 106 Side guide 110 Outer guide 111 Inner guide 122 Motor 123 Gear support plate 124 Cover member 126 Dynamic gear 127 Two-stage reduction gear 130 First transmission gear 131 Second transmission gear 132 Third transmission gear 133 Roller drive gear 134 Pulley 135 Pulley 136 Endless belt 140 Housing 141 Engagement convex part 142 Engagement concave part 143 Extension plate 144 Handle 145 Cover 146 Rotating shaft 154 Opening 155 Cover plate 156 Screw 157 Connection 158 Roller shaft 159 Gear 160 Gear 161 Motor 162 One-way clutch 163 One-way clutch

Claims (5)

In a housing in which a paper supply unit, a recording unit, and a paper discharge tray are arranged at predetermined positions, a paper conveyance unit that conveys the paper conveyed from the paper supply unit to the recording unit and discharges the paper to the paper discharge tray is provided. In an image forming apparatus in which an image reading unit having a document mounting table for reading a document in a stationary state is disposed on the upper surface of the housing, a fixing unit of the recording unit is disposed close to a side frame of the housing. In addition, the image forming apparatus is characterized in that the exterior body of the image reading unit has a protrusion that protrudes at least in a horizontal direction in a side frame portion where the fixing unit is disposed in proximity. The image forming apparatus according to claim 1, wherein a manual sheet feed tray is provided on the side frame portion so as to be freely opened and closed. The outermost position where the manual sheet feed tray projects in the horizontal direction from the side frame portion in the open state is set inside the outermost position in the horizontal direction of the projecting portion. Item 3. The image forming apparatus according to Item 2. 4. The image forming apparatus according to claim 1, wherein a reverse transport unit is mounted on the side frame portion. 5. The outermost position where the reverse transport unit projects horizontally from the side frame portion is set inside the outermost position in the horizontal direction of the projecting portion. Image forming apparatus.

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