JPH11217144A - Image forming apparatus and sheet conveying apparatus - Google Patents

Abstract

(57) [Summary] [PROBLEMS] If a sheet falls in a reversing path and stays during jam processing, a succeeding sheet cannot smoothly enter the reversing path, causing a bending jam. SOLUTION: At least one sheet stacking means 2a to 2f for stacking sheets S for image formation, an exterior cover 42 surrounding the sheet stacking means, and one side of the sheet stacking means. Further, in the image forming apparatus having the substantially vertical reversing paths 29 and 40 for reversing the sheet, the slit-shaped opening 42a opened in the outer cover in a substantially horizontal direction, and the slit-shaped opening and the lower part of the reversing path are formed. Provide an inclined path that communicates.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine and a printer, and more particularly to an improvement in an image forming apparatus having a sheet reversing mechanism.

[0002]

2. Description of the Related Art In a conventional image forming apparatus, as shown in FIG. 7, an image forming section B of the apparatus main body 1 has a reversing mode for performing a double-side mode for forming images on both sides of a sheet S such as paper. A path 129 and a forward / reverse roller pair 132 are provided.
Further, a reversing path 140 is provided in the cassette ぺ Dental C ′ as a sheet feeding table, and the sheet S on which an image is formed on one side is once sent to the reversing path 129 by the normal rotation of the pair of normal and reverse rollers 132. Next, the forward / reverse rotation roller pair 13
By reversing 2, the inverted sheet S is transported from the transport path 118 to the image forming unit, and an image is formed on the other surface of the sheet S. In the case of a long sheet, the long sheet can be inverted by feeding a part of the sheet to the reversing path 140 of the cassette ぺ distal C '.

[0003]

However, in the conventional image forming apparatus as described above, the opening / closing guide 13 is provided.
When the opening / closing guide 130 is opened in order to perform a jam clearing operation on the sheet S that is retained between the forward and reverse rotation roller pairs 132 provided on the inner side of the sheet S, the sheet S falls into the reversing path 140 and stays. S blocks the reverse path 140. In this case, the succeeding sheet that has entered at the time of reversing cannot smoothly enter the reversing path 140, and a bending jam may occur.

In order to prevent this, a paper detection sensor may be provided inside the reversing path, or the cover may be opened and closed to remove the staying sheet. However, a large space is required and the cost of the apparatus is increased. In some cases, the procedure for cleaning up the paper or jam processing may be increased, or the sheet that has been torn and left inside the machine may not be detected by the sensor.

[0005] Further, as shown in FIG.
When the finisher F 'is mounted on the paper discharge side of the printer and a sheet stays due to a jam in the reversing path 140, the cassette ぺ Distal C'
Must open the exterior door. For this reason, the finisher F 'must be largely moved to create an open space for the exterior door.

Further, when the sheet is inverted only outside the machine, the operator's hand may touch the sheet. Therefore, sheet reversal is performed in the apparatus. However, if a sheet falls in a reversing path during a jam, a large space is required because one side of the guide is opened to take out the sheet.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems by forming an image with a relatively simple structure and enabling a sheet reversing operation without causing a jam or the like due to a sheet dropped in a reversing path. It is intended to provide a device.

[0008]

In order to achieve the above object, according to a first aspect of the present invention, at least one sheet stacking unit for stacking sheets for image formation and a periphery of the sheet stacking unit are surrounded. In an image forming apparatus having an exterior cover and a substantially vertical reversing path for reversing a sheet, which is disposed on one side of the sheet stacking means, a slit-shaped opening opened substantially horizontally in the exterior cover. And an inclined path communicating the slit-shaped opening with the lower part of the inversion path.

According to a second aspect of the present invention, there is provided a sheet conveying apparatus having a pair of rollers for nipping and conveying a sheet along a conveying path extending in a vertical direction and separating means for separating the pair of rollers. A discharge path for discharging the sheet out of the apparatus when the sheet held between the pair falls due to the separation of the roller pair is provided below the transport path.

According to these configurations, for example, the sheet is retained while being sandwiched between the forward / reverse roller pairs provided on the apparatus main body side, and the sheet is supplied by opening the forward / reverse roller pairs to remove the sheet. Even if the sheet falls into the reversing path on the paper board side, the sheet freely falls from the reversing path through an opening formed in the outer cover of the paper feeding board and is discharged out of the paper feeding board. For this reason, the sheet does not stay in the reversing path, and it is possible to prevent the sheet from being hindered from being turned over and the unreasonable load from being imposed on the forward / reverse rotation roller pair.

In the case where an accessory such as a finisher is disposed adjacent to the slit-shaped opening of the outer cover, the accessory may be provided with a space allowing discharge of a sheet from the slit-shaped opening or a slit. By providing a tray for receiving the sheets discharged from the opening, it is possible to eliminate the necessity to move the attachment device largely for jam clearance.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) First, an overall configuration of an image forming apparatus according to a first embodiment of the present invention will be described with reference to FIGS.

In these figures, an image forming apparatus main body 1 is shown.
An image reading unit A for reading image information of a document is disposed above the image forming unit, and an image forming unit B for recording an image corresponding to the image information on the sheet S is disposed below the image reading unit A.

In the image forming section B, cassettes 2a and 2b as sheet stacking means for storing the sheets S are arranged. The sheets S fed out of the cassettes by the pickup rollers 3a and 3b are separated by sheet separating means (see FIG. The sheets are separated one by one by an unillustrated sheet, and are fed through a feed path 17 to a position of the electrophotographic photosensitive drum 5 which is a part of an image forming unit provided in the image forming unit B.

A cassette pedestal C is disposed below the main body 1 of the image forming apparatus, and the cassettes 2c and 2c serving as sheet stacking means are provided inside the main body 1 similarly to the main body 1 of the image forming apparatus.
2d, 2e, and 2f are arranged so that a large amount of sheets S can be stored. Further, in order to feed the sheets S in the cassette, a pickup roller similar to the apparatus main body 1 and a feeding path communicating with the feeding path 17 of the apparatus main body 1 are provided.

On the sheet discharge side of the cassette pedestal C, there is provided a transport path 40 as a reversing path through which the sheet S passes. The transport path 40 has an upper entrance side of the transport path 40 and a transport path 29 as a reversing path of the image forming apparatus main body 1. Positioning pins (not shown) are provided at the upper part of the cassette pedestal C, and positioning holes (not shown) are provided at the lower part of the image forming apparatus main body 1 so that the lower surface of the image forming apparatus is aligned with the outlet side. The main body 1 and the cassette pedestal C are positioned by fitting them. Transport paths 29, 40
Can be called a switchback path in which the sheet switches back and reverses. A taper having a funnel-shaped cross section is formed at the upper end of the conveyance path 40 to facilitate sheet entry.

When the image forming apparatus main body 1 starts copying in the double-sided copy mode, the image information of the document set on the document table 15 is read by the image reading means 8 by driving the scanning optical 7.

A laser beam L is emitted by a laser scanner 9 based on the image information read by the image reading means 8 to form a latent image, which is an electrostatic image, on the surface of the photosensitive drum 5. The toner is supplied from the developing device 16 to form a toner image and visualized. At the same time, the sheet S supplied from the cassette 2b via the feed path 17 is positioned by the registration roller pair 4 and conveyed between the photosensitive drum 5 and the transfer roller 6 as a transfer unit. Is transferred to the surface of the sheet S. The transferred sheet S is conveyed by a conveying belt 11 and includes, for example, a fixing roller 12a and a pressing roller 12a.
The toner image is fixed to the sheet S by being sent to the fixing device 12 constituted by the fixing device 12b and subjected to heating and pressure processing by the fixing device 12.

In the single-sided copy mode, the fixed sheet S is fed to the discharge tray 20a by the inner discharge roller pair 21 and the outer discharge roller pair 22 provided in the multi-stage discharge tray unit (attached device) D. The paper is discharged to the paper discharge trays 20b and 20c by the roller pairs 35, 36 and 39.

In the case of the double-side copy mode, the sheet S on which an image is formed on one side is conveyed by an inner discharge roller pair 21 driven by roller driving means (not shown).
It is guided by the flapper 23, passes through the pair of transport rollers 24, is directed downward in the transport direction by the flapper 26, passes through the transport path 25, and is further provided with a switching means for sheet progression or an elastic material such as a resin provided for branching. It passes through the sheet 28. The sheet S is further fed to a transport path 29 as a reversing path by a pair of forward / reverse reversing rollers (consisting of rollers 32a and 32b) 32 capable of rotating forward and backward. The transport path 29 is formed by the inside of the opening / closing guide 30 and the guide 29a on the apparatus main body side.

At this time, the position of the rear end of the sheet S is detected by sheet detecting means (not shown), and the sheet S is conveyed by the forward / reverse roller pair 32 until the sheet S passes through the elastic sheet 28 according to the detected signal. At this point, the pair of forward / reverse rollers 32 is reversed. Thus, the sheet S is conveyed backward, passed through the conveyance path 27 by the elastic sheet 28, and conveyed to the conveyance path 18 by the pair of entrance rollers 18a. Thus, the sheet S is inverted. Here, when the length of the sheet S is short, the inversion of the leading end of the sheet S ends in the transport path 29 of the image forming apparatus main body 1, but when the length of the sheet S is long, the leading end of the sheet S is After passing through the transport path 29, the cassette pedestal C is fed to the transport path 40 as a reversing path and is reversed.

In order to form an image on the back surface, the inverted sheet S passes through the conveyance path 18, passes through the feeding path 17 in the same manner as the image formation on the front side, and is positioned by the registration roller 4. On the other hand, in the image forming section B, an image is formed on the photosensitive drum 5, and the image is transferred to the sheet S by the transfer roller 6. The sheet S to which the image has been transferred is transported by the conveyor belt 11.
To the fixing device 12, where the image is fixed, and is sent to the multi-stage paper ejection tray unit D. The flapper 23 in the multi-stage output tray unit D is provided with switching means (not shown).
Is moved to the position shown by the two-dot chain line in FIG. The sheet S is discharged and stacked on the discharge tray 20a by the external discharge roller 22, and the duplex copying is completed.

Next, a sheet conveying mechanism (sheet conveying apparatus) in the image forming apparatus of this embodiment will be described with reference to FIGS.
Will be described in detail. Reference numeral 30 denotes an opening / closing guide for forming the reversing path 29. One of the forward / reverse rotation roller pair 32 is provided on the opening / closing guide 30, and the other is provided on the apparatus main body side. Reference numeral 30a denotes a rotating hinge provided below the opening and closing guide 30 so as to be rotatable. 3
Reference numeral 0b denotes a locking portion provided on the opening / closing guide 30, and a hook 33 provided on the multi-stage discharge tray unit D is engaged with the locking portion.

Reference numeral 30c denotes a wire stretched between the opening / closing guide 30 and the apparatus main body 1 to adjust the opening angle of the opening / closing guide 30, 31 denotes a guide roller for guiding the opening / closing guide 30, and 33 denotes a guide roller of the opening / closing guide 30. Reference numeral 34 denotes a spring for engaging the locking portion 30b to open the opening / closing guide, and a spring 34 for applying tension to the hook 33. 24,3
5, 36, and 39 are transport rollers, and 23, 26, and 37 are flappers.

Reference numeral 40 denotes a transport path which is disposed substantially vertically on the paper discharge side of the cassette pedestal C, and serves as a reversing path which also serves as a storage section when reversing long sheets as described above.
Is provided on the cassette pedestal main body side,
Is a plate-like inner vertical guide part that forms one side of the vertical guide. 4
An outer guide 2b forms the other side of the transport path 40, and includes a plurality of guide ribs formed integrally with the outer cover 42. The lower part of the inner vertical guide portion 41
The inclined guide portion 41b is connected via the curved portion 41a provided with. A curved portion corresponding to the curved portion 41a is also formed below the rib of the outer guide 42b. For this reason, the lower part (discharge path) of the transport path 40 is smoothly inclined outward as it goes down, and the discharge of the sheet S to the outside of the cassette pedestal C is smooth.

Reference numeral 42a denotes a slit-shaped opening (discharge port) provided at a part, preferably a lower part, of the outer cover 42.
Therefore, the opening width is larger than the maximum width of the sheet S. 4
Reference numeral 2c denotes a conduction guide that guides the sheet from the lower portion of the inclined guide 41b to the opening 42a, and is formed integrally with the outer cover 42 and forms a guide path together with the guide 41.

In FIG. 4, reference numeral 50 denotes a vertical rotation axis of the multi-stage discharge tray unit D. At the time of jam clearance in the transport path 29, the paper discharge tray unit D is rotated from a working position shown by a solid line in the figure around a vertical rotation shaft 50 to an open position shown by a two-dot chain line.

Next, the processing of the staying sheet sandwiched between the forward / reverse rotation roller pair 32 will be described.

(1) Discharge tray (first bin tray) 20
In the case of the reverse discharge mode to A, when the A3 and A4 size sheets are reversed and discharged to the discharge tray 20a, the sheets that pass through the fixing device 12 and are conveyed by the inner discharge roller pair 21 are illustrated in FIG. 1 and a pair of transport rollers 2 by a flapper 23 at a position indicated by a broken line
Guided to 4. When the trailing end of the sheet being conveyed by the pair of conveying rollers 24 passes through the flapper 23, the pair of conveying rollers 24 starts rotating in the opposite direction to that before, and switches the sheet back. The sheet that has been switched back is guided to the outer discharge roller pair 22 by the flapper 23, and is discharged onto the discharge tray 20a.

The sheet switches back without passing through the conveying roller pair 24 to the downstream side. At this time, if a jam (transport error) occurs in any of the image forming apparatuses,
A control circuit (control means) (not shown) stops the transport roller pair 24 and stops the sheet transport. Even if the conveyance is stopped, the sheet does not fall into the conveyance path 40 in the cassette pedestal C because the sheet is nipped by the conveyance roller pair 24. .

The jam processing is performed by opening the opening / closing guide 30 and pulling out the sheet from between the conveying roller pair 24.

(2) Discharge trays 20b and 20c (in the case of the reverse discharge mode to the second bin and the third bin) When the sheet is inverted and discharged to one of the discharge trays 20b and 20c, the image is fixed. Thereafter, the sheet guided by the flapper 23 and conveyed by the conveying roller pair 24 is guided by the flapper 26 to the forward / reverse rotation roller pair 32. When the sheet rear end passes through the flapper 26,
The forward / reverse roller pair 32 starts to rotate in the opposite direction to that before, and switches back the sheet. The sheet that has been switched back is guided to the transport roller 35 by the flapper 26. At this time, the flapper 37 changes the sheet advancing direction to the direction in which the sheet is discharged to the sheet discharge tray 20 b by the conveying roller 36 and the sheet
The direction is switched to one of the directions of discharging to 0c.

When a jam occurs and the control circuit stops the forward / reverse rotation roller pair 32 and the sheet conveyance is stopped, when the open / close guide 29 is opened, the rollers 32a and 32b constituting the forward / reverse rotation roller pair 32 are separated. Therefore, the sheet sandwiched by these rollers falls into the conveyance path 40 in the cassette pedestal C, and is discharged out of the apparatus through the opening 42a.

(In the case of the double-sided copy mode) In the double-sided copy mode, the sheet on which the image is formed on one side is sent to the photosensitive drum 5 and the transfer roller 6 again to form the image on the other side. In this double-sided mode, the sheet is guided by the flapper 23 to the transport roller pair 24 after the image is fixed, and further guided by the flapper 26 to the forward / reverse rotation roller pair 32. When the rear end of the sheet passes through the elastic sheet 28, the forward / reverse rotation roller pair 32 starts to rotate in a direction opposite to the previous direction,
Switch back the seat. The switched back sheet is guided to the transport path 27 by the elastic sheet 28,
The sheet is further conveyed in the conveying path 18 by the conveying rollers 18a to 18d.

When a jam occurs and the control circuit stops the forward / reverse rotation roller pair 32 and the sheet conveyance is stopped, when the open / close guide 29 is opened, the rollers 32a and 32b constituting the forward / reverse rotation roller pair 32 are separated. Therefore, the sheet sandwiched by these rollers falls into the conveyance path 40 in the cassette pedestal C, and is discharged out of the apparatus through the opening 42a.

In the present embodiment, the lower portion of the transport path 40 is a guide path that is inclined and opened to the outside of the cassette pedestal C by the guide curved portion 41a, the guide slope 42c, and the guide rib 42b. It is dropped and discharged out of the cassette pedestal C without staying on the way. Also, the sheet S curled in the direction opposite to the guide path is discharged to the outside of the cassette pedestal C without stopping because the curved portion 41a of the reversing guide path 40 has an R, so that the sheet tip is caught or the like. .

(Second Embodiment) FIG. 6 shows a second embodiment of the present invention.
An overall configuration of an image forming apparatus according to an embodiment will be described. Since the basic configurations of the image reading unit A, the image forming unit B, and the cassette pedestal C of the image forming apparatus of the present embodiment are the same as those of the first embodiment, the same reference numerals are given to the same parts as those of the first embodiment. doing.

However, a finisher F is connected to the image forming apparatus of the present embodiment in place of the multi-stage discharge tray unit D of the first embodiment. Further, in the first embodiment, the forward / reverse rotation roller pair 32 can be separated by opening the opening / closing guide 30. In the present embodiment, however, the internal separation mechanism (not shown) is operated by a switch operation or a lever operation. Mechanism) the forward / reverse rotation roller pair 32
Are separated from each other.

The finisher F is connected to the main assembly 1 of the cassette pedestal C in such a manner as to be adjacent to the outer cover having the opening 42a. A space SP for allowing the sheet to be discharged from the opening 42a is provided inside the lower part of the finisher F (or, if the space SP originally exists in the lower part of the finisher F, the opening SP). 42a is provided at a position corresponding to the space SP), and a tray T for receiving the sheet S discharged from the opening 42a is provided below the space SP.

In the image forming apparatus of the present embodiment, when a jam occurs and the control circuit stops the forward / reverse rotation roller pair 32 and the sheet conveyance stops, the internal separation mechanism separates the forward / reverse rotation roller pair 32. Then, the sheet sandwiched by these rollers falls into the conveyance path 40 in the cassette pedestal C, and is discharged out of the apparatus through the opening 42a. And the lower space S of the finisher F
P is placed on the tray T.

As described above, according to the present embodiment, even when the finisher F is disposed so as to cover the opening 42a of the cassette pedestal C, the sheet can be discharged from the lower part of the finisher F without obstructing sheet discharge from the opening 42a. Can be discharged. For this reason, the forward / reverse rotation roller pair 3
When performing the jam clearance in a state where the sheet is sandwiched in 2, the finisher F does not need to be largely moved,
Jam processing can be facilitated.

[0042]

As described above, according to the present invention,
When a sheet stays in the apparatus and the jam is cleared, even if the sheet falls on the reversing path or the conveyance path, the sheet does not stay there and is smoothly discharged to the outside of the apparatus. it can.

Further, since the sheet dropped in the reversing path or the conveying path does not stay, the reversing operation of the succeeding sheet due to the stay of the preceding sheet is not hindered, and the deterioration of the jam can be prevented. In addition, the configuration of a sheet detection sensor for detecting the sheet reversal in the reversing path or the conveyance path and the opening / closing means of the outer cover for dropping sheet processing can be omitted, and the apparatus can be simplified in configuration.

When an accessory such as a finisher is disposed adjacent to the slit-shaped opening of the outer cover, the accessory may be provided with a space for permitting sheet discharge from the slit-shaped opening, or may be provided with a slit. By providing a tray for receiving the sheet discharged from the opening, it is not necessary to move the attached device greatly for the jam clearance, and the jam clearance can be further facilitated.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view showing the interlocking of a multi-stage paper discharge tray unit and an opening / closing guide of the image forming apparatus.

FIG. 3 is a schematic cross-sectional view illustrating a relationship between the multi-stage sheet discharge tray unit and an opening / closing guide.

FIG. 4 is a plan view showing the relationship between the rotation axis of the multi-stage paper discharge tray unit and the apparatus main body.

FIG. 5 is a perspective view of an outer cover of a cassette pedestal of the image forming apparatus.

FIG. 6 is a schematic sectional view of an image forming apparatus according to a second embodiment of the present invention.

FIG. 7 is a schematic sectional view showing an example of a conventional image forming apparatus.

FIG. 8 is a schematic sectional view showing an example of a conventional image forming apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus main body 2a-2f ... Cassette 5 ... Photosensitive drum 6 ... Transfer roller 12 ... Fixing device 16 ... Developing device 17 ... Feeding path 18 ... Conveying path 20a-20c ... Discharge trays 21, 22 ... Discharge rollers Pairs 23, 26, 37 flapper 24, 36, 39 transport roller pair 29, 40 transport path (reversing path) 30 opening / closing guide 30b locking part 31 guide roller 32 forward / reverse roller pair 33 hook 34 ... Spring 41 ... Inner vertical guide part 41a ... Bending part 41b ... Inclination guide part 42 ... Outer cover 42a ... Opening part 42b ... Outer guide 42c ... Conduction guide part 50 ... Rotating axis A ... Image reading part B ... Image forming part C: Cassette pedestal F: Finisher S: Sheet

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI G03G 15/00 550 G03G 15/00 550

Claims (20)

[Claims] At least one sheet stacking means for stacking sheets for forming an image, an outer cover surrounding the sheet stacking means, and a sheet reversal disposed on one side of the sheet stacking means. An image forming apparatus having a substantially vertical reversing path for: a slit-shaped opening formed in the exterior cover in a substantially horizontal direction, and an inclined path communicating the slit-shaped opening and a lower part of the reversing path. An image forming apparatus comprising: 2. The method according to claim 1, wherein the reverse path and the inclined path include an outer guide formed on the outer cover,
An image forming apparatus comprising: an inner guide that faces the outer guide with a gap therebetween and is located on a sheet feeder main body side. 3. The outer guide according to claim 2, wherein
An image forming apparatus comprising a plurality of ribs provided on the exterior cover and extending in a substantially vertical direction. 4. The apparatus according to claim 2, wherein the inner guide includes a substantially vertical vertical guide formed on a side of the paper feed tray main body, an inclined guide connected to a lower portion of the vertical guide, An image forming apparatus provided on an exterior cover, wherein the image forming apparatus is formed of a conduction guide portion that conducts a sheet from the inclined guide portion to the slit-shaped opening. 5. The image forming apparatus according to claim 2, wherein the vertical guide and the inclined guide of the inner guide are connected by a curved portion. 6. The image forming apparatus according to claim 2, wherein the inner guide is formed of a plate. 7. The image forming apparatus according to claim 1, wherein an upper end of the reversing path has a funnel-shaped taper when viewed in cross section. 8. A sheet feeding device according to claim 1, wherein a feeding path for feeding a sheet to an image forming means is provided at one side of said sheet stacking means, and at another side of said sheet stacking means. An image forming apparatus, wherein the reversing path for receiving a sheet on which an image is formed on one side by an image forming unit is provided. And a pair of rollers for pinching and conveying the sheet along a conveying path extending in a vertical direction, and separating means for separating the roller pair, wherein the sheet pinched by the roller pair is A sheet conveyance device, wherein a discharge path for discharging the sheet to the outside of the apparatus when the sheet falls due to separation of the roller pair is provided below the conveyance path. 10. A pair of rollers for nipping and transporting a sheet along a transport path extending in a vertical direction, and a guide which forms at least a part of the transport path and is movable to open the transport path. Wherein the roller pair is configured to separate when the guide is opened, and discharges the sheet out of the apparatus when the sheet held between the roller pair drops due to the separation of the roller pair. A sheet discharging device provided below the conveying path. 11. The sheet conveying device according to claim 9, wherein the roller pair switches back the sheet introduced into the conveying path. 12. The sheet conveying apparatus according to claim 9, wherein the guide is formed integrally with an outer cover of the apparatus. 13. The sheet conveying apparatus according to claim 12, wherein a part of the discharge path is formed in the outer cover, and a discharge port of the discharge path is provided in the outer cover. 14. The device according to claim 12, wherein an attachment device is detachably connected to the main device at a position on at least a part of the outer cover on a side of the main device. Sheet conveying device. 15. The sheet conveying apparatus according to claim 14, wherein the attachment device has a tray on which sheets discharged from the main body device are passed through a discharge path different from the discharge path. . 16. The space according to claim 14, wherein the attachment device is disposed at a position adjacent to the outlet in the exterior cover, and the accessory device allows a sheet to be discharged from the outlet. A sheet conveying device comprising: 17. The sheet conveying device according to claim 16, wherein a tray for receiving the sheet discharged from the discharge port is provided in the accessory device. 18. The sheet conveying apparatus according to claim 9, wherein the discharge path allows the sheet to fall freely and discharge the sheet to the outside of the apparatus. 19. The sheet conveying apparatus according to claim 9, further comprising control means for stopping conveyance of the sheet by the roller pair when a sheet conveyance abnormality occurs. 20. An image forming apparatus comprising: the sheet conveying device according to claim 9; and an image forming unit that forms an image on a sheet.