JP3877367B2 - Image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus such as a copying machine, a printer, and a facsimile apparatus using an electrophotographic system.
[0002]
[Prior art]
In recent years, image forming devices such as copiers, facsimiles, and printers have become widespread. This is based on a copying machine, and when used as a printer, a reversing mechanism is mounted on a peripheral device so that sheets can be output in page order. However, due to the recent rapid spread of personal computers, printer-structured devices are becoming main.
[0003]
Therefore, what is proposed is a so-called vertical conveyance path method (a sheet feeding device at the lower part of the apparatus, an image forming unit thereon, a paper discharge unit at the upper part of the apparatus, and a sheet is conveyed vertically, The method of discharging a sheet on which an image is formed). With this method, the sheet conveyance path is much shorter than conventional copiers, the output time from paper feeding to paper ejection can be shortened, sheet conveyance is improved, and the side cover is opened. By doing so, most of the conveyance path can be opened, so that it is easy to remove the jammed sheet.
[0004]
[Problems to be solved by the invention]
The above-described technique has a problem that since the discharge path after sheet fixing cannot be opened, if a jam occurs on the sheet in the paper discharge unit, there is no jam processing space, and the jam processing is troublesome.
When the above-described vertical conveyance path method is equipped with a duplex unit for forming images on both sides of a sheet, the following problems occur in the paper discharge unit.
1. In the vertical direction conveyance path method, the double-sided unit is mounted on the cover side provided on the side surface of the apparatus that is opened during the jam processing, so that the jam removal performance is deteriorated. In addition, the paper discharge unit requires a normal paper discharge path and a double-sided conveyance path. Even if the cover is opened during jam processing, the normal paper discharge path is positioned behind the double-sided conveyance path. As a result, jam removal is poor.
[0005]
SUMMARY OF THE INVENTION An object of the present invention is to provide a low-cost image forming apparatus that can easily perform jam processing.
[0006]
[Means for Solving the Problems]
According to the first aspect of the present invention, there is provided an image forming unit for transferring an image formed on an image carrier to a sheet and fixing the image with a fixing device to form an image, and the sheet provided below the image forming unit. A sheet feeding device that conveys the sheet to the image forming unit, a sheet discharge unit that is provided above the image forming unit and has a sheet discharge tray on which the sheets are stacked, a side cover that opens the sheet conveyance path, A duplex unit that is disposed outside the side cover and that reverses the sheet; and a path switching member that selectively guides the sheet from the fixing device to the discharge tray or the duplex unit. In the image forming apparatus in which the image forming unit forms an image on the sheet while conveying the sheet substantially vertically from the sheet feeding device, and the sheet on which the image is formed is discharged to the sheet discharge tray. The side cover is detachably attached to the main body of the image forming apparatus, and the side cover includes a double-sided exit guide plate for guiding the sheet discharged from the fixing device to the double-sided unit, and the sheet from the paper discharge unit to the double-sided unit A removable relay roller for transporting, and when the duplex unit is mounted, the duplex guide is provided when the transport path is opened by the side cover with the duplex unit detached from the side cover. The plate and the relay roller open the sheet discharge path in the sheet discharge unit, and when the duplex unit is not mounted, the conveyance path is opened by the side cover with the relay roller removed. Sometimes, the double-sided exit guide plate opens the sheet discharge path in the sheet discharge section.
[0007]
According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the side cover has a receiving port for receiving a sheet discharged from the duplex unit to a conveyance path in the main body of the image forming apparatus after being reversed. It is characterized by that.
[0008]
【Example】
First, a reference example as a basis of the embodiment of the present invention will be described with reference to FIGS. In FIG. 1, reference numeral 10 denotes an image forming apparatus main body, and reference numeral 20 denotes a scanner that reads a document that is formed separately from the image forming apparatus main body 10.
The image forming apparatus main body 10 is provided above the image forming unit 60, an image forming unit 60 that forms an image, a paper feeding device 30 that is provided below the image forming unit 60, and that conveys the sheet P to the image forming unit 60. And a paper discharge unit 70 for discharging and stacking sheets P on which images are formed.
[0009]
As shown in FIGS. 1 and 2, the image forming unit 60 includes a photoconductor 11 as an image carrier, an optical writing device 40 that forms an electrostatic latent image on the photoconductor 11, and charging that uniformly charges the photoconductor 11. A transfer device 12, an eraser (not shown) for erasing the charge in the non-image portion, a developing device 14 for visualizing the electrostatic latent image, and a visible image formed by the developing device 14 is transferred to the sheet P, The transfer device 15 that conveys the sheet P, the fixing device 50 that melts and fixes the toner image transferred by the transfer device 15, and the cleaning that removes the toner remaining on the photoconductor 11 after the transfer and cleans the photoconductor 11. A unit 16 and a static eliminator 19 for erasing charges remaining on the photoconductor 11 after transfer are provided. Reference numeral 80 denotes a toner bottle for storing toner to be supplied to the developing device 14.
[0010]
The optical writing device 40 is a unit that converts the image data from the scanner 20 into an optical signal and performs optical writing corresponding to a document image and optical writing according to image information from a personal computer. The beam is scanned through the polygon mirror 43 rotated by the drive motor 42, and the scanning light is guided to the photoconductor 11 by the fθ lens 45 through the reflecting mirror 44 to form an electrostatic latent image.
[0011]
The cleaning unit 16 includes a blade 17 in contact with the photoconductor 11 and a brush 18 disposed on the downstream side of the blade 17 in the rotation direction of the photoconductor 11.
[0012]
A transfer belt 22 of the transfer device 15 is disposed so as to contact the photoreceptor 1, and this transfer belt 22 is stretched between a driving roller 23 and a driven roller 24 and has an electric resistance of medium resistance. Yes, it is made of a rubber material with little resistance change. A coating material having a low friction coefficient is used on the surface of the transfer belt 22.
[0013]
A bias roller 27 for applying a bias voltage is disposed in contact with the inner peripheral surface of the transfer belt 22 at a position away from the nip between the photoreceptor 11 and the transfer belt 22 by a predetermined distance toward the drive roller 23. . The bias roller 27 is a metal roller, and is rotated by the rotation of the transfer belt 22 and connected to a high voltage power source that applies a bias voltage (not shown).
[0014]
The fixing device 50 includes a pair of fixing rollers 51 and 52, a cleaning roller 54 in contact with the fixing roller 52, and a separation claw 53 disposed in contact with the fixing roller 51.
The paper feeding device 30 has a plurality of paper feeding cassettes 31, and feeds a sheet P from one of them by a paper feeding roller 32, and separates the fed sheets P one by one by a pair of separation rollers 35. Then, it is transported by the transport roller 36 and sent out to the transport path 33. In front of the transfer device 15 on the conveyance path 33, registration rollers 34a and 34b for feeding the sheet P between the transfer device 15 and the photosensitive member 11 at a predetermined timing are arranged.
[0015]
The paper discharge unit 70 includes a single-sided exit guide plate 72 for guiding the sheet P from the fixing device 50 to the upper surface portion 61 of the apparatus main body as a paper discharge tray, upper and lower paper discharge guide plates 73 and 74, and lower paper discharge. A sheet discharge frame 75 that supports the guide plate 74 and a sheet discharge roller pair 78 that sends the sheet P to the upper surface portion 61 are provided. Reference numeral 76 denotes a paper discharge sensor that detects passage of the sheet P. The lower paper discharge guide plate 74 is formed integrally with the paper discharge frame 75, and the upper paper discharge guide plate 73 is formed integrally with the exterior cover 77 of the apparatus main body, and these members are respectively attached to and detached from the apparatus main body. It is free.
[0016]
As shown in FIG. 2, a side cover 71 for opening the conveyance path 33 of the sheet P and performing jam processing is provided on the side surface of the image forming unit 60 so as to be openable and closable around a shaft 71a. The side cover 71 supports the transfer device 15 and the registration roller 34a. At the free end of the side cover 71, a groove 71 b is formed in which the engagement protrusion 72 a of the single-sided outlet guide plate 72 is engaged. The single-sided outlet guide plate 72 is detachable from the side cover 71. ing.
In addition, a receiving port 71c for receiving a sheet discharged from the duplex unit to be described later to the conveying path 33 is formed in the vicinity of the shaft 71a of the side cover 71, and this receiving port 71c is a thin wall provided inside the receiving port 71c. One-way traffic is restricted by the elastic piece 71d.
When the side cover 71 moves from the position indicated by the phantom line in the drawing to the position indicated by the solid line, the single-sided outlet guide plate 72 also moves, opens the sheet P conveyance path 33 and fixes the fixing device. The discharge path for the 50th and subsequent sheets P is opened.
[0017]
The scanner 20 is placed on the rack 2, and includes a contact glass 21 on which a document is placed, an illumination lamp 3 that irradiates light on the document placed on the contact glass 21, and reflected light from the surface of the document. It comprises a scanning mirror 4 that reflects back, a pair of optical path folding mirrors 5 a and 5 b that move at half the speed of the scanning mirror 4, an imaging lens 6, and a CCD 7.
[0018]
The operation based on the above configuration will be described.
The optical writing device 40 performs optical writing on the surface of the photoconductor 11 whose surface is uniformly charged by the charger 12 according to information on the image of the original read by the scanner 20 or the image from the personal computer. An electrostatic latent image is formed. The electrostatic latent image on the photoconductor 11 is formed with a visible image formed by adhering the toner charged by the developing device 14 by the developing roller 14a after the charge of the non-image portion is erased by the eraser.
[0019]
On the other hand, the sheet P is fed from one sheet feeding cassette 31 of the sheet feeding device 30 by the sheet feeding roller 32, separated one by one by the separation roller 35, and sent to the conveyance path 33 by the conveyance roller 36, and the registration roller Sent to the pair 34a, 34b. The registration roller pairs 34 a and 34 b send the sheet P to the transfer device 15 at a timing at which the visible image on the photoreceptor 11 and the sheet P coincide with each other at the nip between the photoreceptor 11 and the transfer belt 22.
[0020]
In accordance with the timing when the sheet P enters the nip, a predetermined voltage is applied from the high voltage power source to the bias roller 27 to charge the transfer belt 22 and transfer the toner on the photoreceptor 11 onto the sheet P. Here, since the sheet P is electrostatically attracted to the transfer belt 22, the sheet P is separated from the photoconductor 11, transported on the transfer belt 22, and curvature-separated from the transfer belt 22 at the position of the driving roller 23, to the fixing device 50. Sent.
The toner on the sheet P is inserted between the fixing roller 51 heated to a predetermined temperature and the fixing roller 52, and after being heated and fixed, is guided to the single-sided outlet guide plate 72, and the upper and lower sheet discharge guide plates. The sheet passes between 73 and 74 and is discharged to the upper surface portion 61 by the discharge roller pair 78.
[0021]
The toner remaining on the photoconductor 11 is removed by the blade 17 and the brush 18 of the cleaning unit 16, and the residual charge on the photoconductor 11 is erased by the static eliminator 19 to prepare for the next image formation.
[0022]
When a jam occurs in the sheet P, the side cover 71 is moved from the position indicated by the phantom line to the position indicated by the solid line in FIG. Then, the discharge path of the sheet P after the fixing device 50 is opened, a jam processing space is secured, and the jammed sheet P can be removed therefrom.
[0023]
3 and 4 show other reference examples. However, the same parts as those in the reference example are not described in detail unless they are particularly necessary.
In this reference example, a function of forming an image on both sides of the sheet P is added to the above-described reference example, that is, the double-side unit 90 that reverses the sheet P from the fixing device 50 and the fixing device 50. A path switching member 88 for selectively guiding the sheet P to the upper surface 61 or the duplex unit 90 and relay rollers 89a and 89b for transporting the sheet P from the sheet discharge unit 70 to the duplex unit 90 are provided. Instead of the plate 72, only a double-sided exit guide plate 82 for guiding the sheet P to the upper surface portion 61 or the double-sided unit 90 and an external cover 87 integrated with the upper paper discharge guide plate 83 instead of the external cover 77 are provided. However, it is structurally different from the above-described reference example.
[0024]
The duplex unit 90 is disposed outside the side cover 71 and is detachable from the apparatus main body. Further, as shown in FIG. The duplex unit 90 receives and reverses the sheet P sent out by the relay rollers 89a and 89b, and a plurality of conveyance rollers 93 that convey the inverted sheet P to the registration roller pairs 34a and 34b through the duplex path 92. And a reversing path 95 and a thin elastic piece 96 that allows only the sheet P to enter the duplex unit 90. The sheet P sent to the duplex unit 90 by the relay rollers 89a and 89b is once received in the reverse path 95, and is switched back by the reverse rotation of the reverse roller 91 and conveyed to the duplex path 92 in a reversed state. ing. Thereafter, the sheet P enters the conveyance path 33 through the receiving port 71c.
[0025]
The route switching member 88 and the relay roller 89a are detachably supported by the upper paper discharge guide plate 83, respectively. The course switching member 88 is selectively switched between a position for guiding the sheet P to the upper surface portion 61 and a position for guiding the sheet P to the duplex unit 90 during duplex copying by means not shown.
[0026]
A relay roller 89b is rotatably supported at the free end of the side cover 71, and an engaging projection 82a of a double-sided outlet guide plate 82 is engaged with the groove 71b. The guide plate 82 is detachable from the side cover 71. The shapes of the engaging protrusions 82a of the double-sided exit guide plate 82 and the engaging protrusions 72a of the single-sided outlet guide plate 72 of the reference example described above are the same, and the double-sided outlet guide plate 82 and the single-sided outlet guide plate 82 72 is freely exchangeable and detachable. As a result, the side cover 71 can be used in common for both the double-sided image type and the single-sided type image forming apparatus, thereby reducing the cost.
[0027]
As shown in FIG. 4, when the side cover 71 moves from the position indicated by the phantom line in the drawing to the position indicated by the solid line in a state where the duplex unit 90 is detached from the side cover 71, The double-sided exit guide plate 82 and the relay roller 89b also move, the sheet P conveyance path 33 is opened, and the sheet P discharge path after the fixing device 50 is also opened.
[0028]
When copying on the back side of the sheet P (double-sided copy), an image is formed on one side of the sheet P by the same process as in the above reference example, and then the sheet P is guided by the path switching member 88 to the double-sided exit guide plate. 82, is sent to the duplex unit 90 by relay rollers 89a and 89b, is switched back in the duplex unit 90, passes through the duplex path 92, and is conveyed again to the pair of registration rollers 34a and 34b. These image forming processes are repeated and stacked on the upper surface portion 61.
[0029]
When a jam occurs in the sheet P, the relay roller 89b and the double-sided exit guide plate move when the side cover 71 is moved from the position indicated by the phantom line to the position indicated by the solid line in FIG. Thus, the sheet P conveyance path 33 and the sheet P discharge path after the fixing device 50 are opened, a jam processing space is secured, and the jammed sheet P may be removed therefrom.
[0030]
Next, an embodiment of the present invention will be described with reference to FIGS. The same parts as those in each of the reference examples are denoted by the same reference numerals, and redundant description of the configuration and functions is omitted unless particularly necessary. Further, since the overall configuration and function of the apparatus are the same as those of the above reference examples, only the portions corresponding to the gist of the invention will be described.
As shown in FIG. 6, the paper discharge unit 100 of the image forming apparatus shown in this embodiment includes a paper discharge guide 101 fixed to the apparatus main body, and a paper discharge positioned and fixed on the upper surface of the paper discharge guide 101. A sensor support substrate 102, a path switching member 103 that is rotatably supported by the paper discharge guide 101, a detachable unit 104 that is detachably attachable to the paper discharge guide 101, and a double-sided / single-sided double-sided exit guide. The board 105 is schematically configured.
[0031]
The paper discharge guide 101 is formed by integrally forming portions corresponding to the upper and lower paper discharge guide plates in the above reference example by molding, and fixing pieces 106 for fixing to the apparatus main body are provided at both ends thereof. I have. On these fixed pieces 106, protrusions 106a for positioning the paper discharge sensor support substrate 102 are formed. The paper discharge guide 101 is provided with paper discharge rollers 107 and 108, and power is input to one end (back side) of the rotation shaft 109 of the upper paper discharge roller 107 from a drive source of the apparatus main body (not shown). The input gear 110 is fixed.
The paper discharge sensor support substrate 102 is provided with a paper discharge sensor 111 that detects the passage of the sheet P.
The course switching member 103 is formed in a triangular prism shape having a rib structure having a space inside, and shafts 103 a supported by the paper discharge guide 101 are formed at both ends. An operation piece 112 for rotating the route switching member 103 is fixed to the back shaft 103a, and the route switching member 103 is interposed between the upper end portion of the operation piece 112 and the side plate of the paper discharge guide 101. The spring 113 that always returns to the fixed position (single-side mode position) is locked. The operation piece 112 is rotatably supported on the side plate by the shaft hole 112a.
[0032]
The detachable unit 104 is formed with an upper discharge port 114 corresponding to a mail box or the like installed above the apparatus main body, and an upper path switching member 115 is rotatably provided below the outlet. An arm 116 is fixed to the rotation shaft 115a on the front side of the upper path switching member 115, and this arm 116 is rotatable on the movable iron core 118 of the solenoid 117 fixed to the side plate on the front side of the detachable unit 104. It is connected. A spring 119 that always returns the upper path switching member 115 to a fixed position (upper sheet discharge position) is engaged between the lower end portion of the arm 116 and the side plate.
A side plate on the back side of the detachable unit 104 is provided with a solenoid 120 as a path switching member driving means. A movable iron core 121 of the solenoid 120 has a lower end of an operation piece 112 fixed to the path switching member 103. A pressing piece 122 that presses the portion is rotatably connected. The pressing piece 122 is rotatably supported on the side plate by an integrally formed shaft 122a.
A relay roller 123 that forms one of a pair of relay rollers corresponding to the relay roller 89a of the reference example is rotatably supported on the back surface side (double-sided mode discharge port side) of the detachable unit 104. A driving gear 125 as a relay roller driving unit is fixed to the end on the back side. The drive gear 125 is rotatably supported by a back side plate of the paper discharge guide 101 and is connected to a relay gear 126 that meshes with the input gear 110 via a belt 127. The drive gear 125 rotates as the input gear 110 rotates. It is supposed to be.
On both sides of the front surface of the detachable unit 104, a protrusion 104a for positioning with respect to the paper discharge guide 101 and a screw hole 104b for screwing are formed. Further, screws are fastened between the two members by a hole 102 a formed on the back side of the paper discharge sensor support substrate 102 and a hole 104 b formed on the front side of the duplex mode unit 104.
Since the relay roller 123 and the drive gear 125 are provided integrally with the attachment / detachment unit 104, the relay roller 123 and the drive gear 125 can be attached to and detached from the discharge guide 101, that is, integrally with the apparatus main body. .
[0033]
Fixing pieces 105a for fixing to a side cover 128, which will be described later, are integrally formed at both ends of the double-sided exit guide plate 105, and two types of guide ribs 129 and 130 are spaced apart in the longitudinal direction on the outer surface. A plurality are formed. The double-sided exit guide plate 105 is formed with a recess 131, and a driven relay roller 132 forming the other of the relay roller pair is rotatably and detachably accommodated. Support plates 133 and 134 that support the rotating shaft 135 of the relay roller 132 are fixed to both ends of the recess 131, respectively, and are supported by the spring 136 accommodated between the support plates 133 and 134 and one support plate 134. The bearing 137 is supported so as to be in pressure contact with the relay roller 123 on the detachable unit 104 side. As shown in FIG. 7, the upper surface of the groove of the support plate 133 that supports the tip of the rotating shaft 135 is set to be narrower than the tip diameter of the rotating shaft 135 so that it can be snap-fitted.
[0034]
The above configuration is a duplex mode configuration. In the case of duplex copying, as shown in FIG. 5, both the solenoid 120 for driving the route switching member 103 and the solenoid 117 for driving the upward route switching member 115 are turned on. The When the solenoid 120 is turned on, the operation piece 112 is pressed by the pressing piece 122, and accordingly, the course switching member 103 is positioned from the single-side mode position at the fixed position to the double-side mode position. Further, when the solenoid 117 is turned on, the arm 116 rotates, and accordingly, the upper path switching member 115 is positioned from the upper discharge position at the fixed position to the duplex mode position. As a result, a discharge path R1 to the duplex unit is formed, and the sheet P exiting the fixing device 50 is sent to the duplex unit.
As shown in FIG. 5, the side cover 128 is formed with a receiving port 128a as in the reference example.
The lower discharge roller 108 is pressed against the upper discharge roller 107 by a leaf spring 138.
The receiving port 128a is not necessarily formed in the side cover 128, but by forming it in the side cover 128, the height of the duplex unit can be suppressed, which contributes to downsizing of the duplex unit and thus the apparatus. be able to.
[0035]
Corresponding to the reversing operation of the sheet P in the duplex unit, the solenoid 120 and the solenoid 117 are turned off as shown in FIG. When the solenoid 120 is turned off, the path switching member 103 returns to the fixed single-sided mode position by the urging force of the spring 113. As a result, a discharge path R2 to the upper surface portion of the apparatus main body is formed, and the double-sided copied sheet P exiting the fixing device 50 is discharged to the upper surface portion (reference numeral 61 in the reference example).
[0036]
When discharging to a mailbox or the like, as shown in FIG. 9, only the solenoid 120 is turned on, and the path switching member 103 is positioned at the duplex mode position. Since the upper path switching member 115 is in the upper sheet discharge mode position which is a fixed position, an upper discharge path R3 is formed, and the sheet P exiting the fixing device 50 is sent to a mail box or the like.
[0037]
FIG. 10 shows a state where the side cover 128 is opened and a jam processing space is secured in the double-sided mode configuration shown in FIG.
[0038]
When used as a single-sided mode machine, as shown in FIG. 11, members used only in the double-sided mode, that is, the detachable unit 104 and the relay roller 132 are removed. When the detachable unit 104 is removed, that is, when the solenoid 120 as the path switching member driving means is detached from the apparatus main body, the path switching member 103 is always in a fixed position by the urging force of the spring 113. A single-sided mode configuration is formed.
[0039]
In this way, the path switching member 103 that bears a part of the discharge path R2 in the single-sided mode is permanently installed, and the double-sided exit guide plate 105 and the side cover 128 are integrated into a common part for the single-sided / double-sided mode. By making the components (solenoid 120, etc.) used only for this purpose detachable, waste due to duplication of functions of the replacement member in mode switching can be reduced.
FIG. 12 shows a state where the side cover 128 is opened and a jam processing space is secured in the single-side mode configuration shown in FIG.
[0040]
【The invention's effect】
According to the first aspect of the present invention, the double-sided exit guide plate and the side cover are common parts for the single-sided mode and the double-sided mode, and the relay roller and the double-sided unit used only for the double-sided mode are configured to be detachable. The paper jamming process is facilitated, and the waste due to the overlapping functions of the replacement member in mode switching can be reduced.
[0041]
According to the invention described in claim 2, since the side cover is formed with the receiving port for receiving the sheet discharged from the duplex unit to the conveyance path in the apparatus main body, in addition to the above effect, the duplex unit can be made small. Has the advantage that
[Brief description of the drawings]
FIG. 1 is a schematic diagram of an image forming apparatus showing a reference example.
FIG. 2 is an enlarged schematic view of a paper discharge unit and an image forming unit in the image forming apparatus shown in FIG.
FIG. 3 is a schematic view of an image forming apparatus showing another reference example.
4 is an enlarged schematic diagram of a paper discharge unit and an image forming unit in the image forming apparatus shown in FIG.
FIG. 5 is a schematic view of a paper discharge unit of the image forming apparatus showing an embodiment of the present invention.
6 is an exploded perspective view of the paper discharge unit shown in FIG.
FIG. 7 is an enlarged plan view of a main part of a relay roller support structure in the outlet guide plate.
8 is a schematic diagram showing a single-sided mode configuration of the paper discharge unit shown in FIG.
FIG. 9 is a schematic diagram illustrating a configuration of an upper discharge mode of the discharge unit illustrated in FIG.
10 is a schematic view showing a state in which a side cover of the paper discharge unit shown in FIG. 5 is opened.
FIG. 11 is a schematic diagram of a paper discharge unit showing a one-side mode configuration.
12 is a schematic diagram illustrating a state in which a side cover of the paper discharge unit illustrated in FIG. 11 is opened.
[Explanation of symbols]
11 photoconductor
12 Charger
14 Development device
15 Transfer device
16 Cleaning unit
21 Contact glass
22 Transfer belt
30 Paper feeder
40 Optical writing device
50 Fixing device
60 Image forming unit
61 Upper surface as the output tray
70, 100 Paper discharge unit
71, 128 Side cover
72 Exit guide plate for one side
73 Upper paper ejection guide plate
82 Exit guide plate for both sides
88, 103 Course switching member
89a, 89b, 123, 132 Relay roller
90 Duplex unit
91 Inversion roller
92 Double-sided path
P sheet
105 Exit guide plate for both sides
120 Solenoid as route switching member driving means
125 Driving gear as relay roller driving means
128 Side cover
128a entrance

Claims (2)

An image formed on the image carrier is transferred to a sheet and fixed by a fixing device to form an image, and the sheet provided below the image forming unit is conveyed to the image forming unit. A sheet feeding device, a sheet discharge unit provided above the image forming unit and having a sheet discharge tray for stacking the sheets, a side cover for opening the sheet conveyance path, and an outer side of the side cover. A duplex unit that reverses the sheet, and a path switching member that selectively guides the sheet from the fixing device to the discharge tray or the duplex unit,
In the image forming apparatus for forming an image on the sheet by the image forming unit while conveying the sheet substantially vertically from the sheet feeding device, and discharging the sheet on which the image is formed to the discharge tray.
The duplex unit is detachable from the main body of the image forming apparatus, and the side cover includes a duplex exit guide plate for guiding a sheet ejected from the fixing device to the duplex unit, and the duplex unit from the ejection unit. A detachable relay roller that conveys the sheet to the unit, and when the double-sided unit is mounted, the double-sided unit is detached from the side cover and when the conveyance path is opened by the side cover, The double-sided exit guide plate and the relay roller open the sheet discharge path in the paper discharge unit, and when the double-sided unit is not attached, the side cover is removed with the relay roller removed. 2. The image forming apparatus according to claim 1, wherein when the conveyance path is opened, the double-sided exit guide plate opens the sheet discharge path in the sheet discharge unit. 2. The image forming apparatus according to claim 1 , wherein the side cover has a receiving port for receiving a sheet discharged from the duplex unit to a conveyance path in the image forming apparatus main body after being inverted .

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