JP2003122072A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make an image forming device able to easily perform a jamming processing. SOLUTION: A printer 100 is provided with a carrying unit 200 loaded to the printer main body 102 an a paper carrying path. The paper carrying path comprises an image forming/carrying path 20, a backward-carrying path 22, a return path 24 and a reverse carrying path 26. The path 24 and the path 26 are formed in the carrying unit 200. The unit 200 is loaded so that the unit 200 can be drawn out in the upstream direction of the carrying path 20. The upstream side area 20a is formed between the top face of the unit 200 and the corresponding base of the printer main body 102 in a state where the unit 200 is loaded. When the unit 200 is drawn out, the upstream side area 20a, the side parts of the path 24 and the path 26 are opened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser printer,
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a facsimile or an electrostatic copying machine, and more particularly to an image forming apparatus capable of forming an image on both sides of a sheet and facilitating jam processing.

[0002]

2. Description of the Related Art An image forming apparatus capable of forming an image on both sides of a sheet, for example, an electrostatic copying machine, is a sheet conveying device for reversing and conveying and storing the sheet, which is orthogonal to the sheet conveying direction. There is disclosed an apparatus provided with a sheet conveying device including a main body frame that is mounted so as to be pulled out to the outside of the main body of the copying machine (for example, Japanese Patent Laid-Open No. 10-212049).
(See the official gazette). The main body frame includes a paper storage unit that stores inverted paper, an upper conveyance unit, a lower conveyance unit, and a link member. The upper and lower transport units having the upper and lower transport guides and the upper and lower transport rollers are arranged above the sheet storage unit and are attached to the body frame so as to be openable and closable. Above the paper transport device inside the copier body,
An image forming conveyance path is provided which extends substantially horizontally in the tangential direction with respect to the outer peripheral surface of the photosensitive drum. An image is formed on one side of the sheet in a well-known manner while the sheet is conveyed through the image forming conveyance path. A paper discharge tray is disposed at the downstream end of the image forming conveyance path and on one side of the copying machine main body. A paper feed cassette is arranged below the paper transport device in the main body of the copying machine.

When the single-sided copy mode is set, the paper fed from the paper feed cassette has an image on one side thereof while being conveyed through the image forming conveyance path to the transfer area of the photosensitive drum and the fixing device. It is formed and discharged onto the paper discharge tray. When the double-sided copy mode is set, the sheet on which the image is fixed on one side is conveyed from the downstream side of the image forming conveyance path with the front and back reversed and between the upper and lower conveyance guides. The paper conveyed between the upper and lower conveyance guides is conveyed between the upper and lower conveyance guides by the upper and lower conveyance rollers, and the front and back sides are further reversed at the downstream end so that the front and back sides are in the same state as when the first single-sided copy was made. Stored in the paper storage unit. The paper stored in the paper storage unit is re-fed by the re-feeding device (ejection device) with the front and back reversed to the upstream side of the image forming conveyance path, and after the image is fixed on the other surface, the paper is ejected. It is discharged onto the tray.

In the above-described paper transporting apparatus, when a paper jam occurs between the upper transporting section and the lower transporting section used for double-sided copying, the main body frame is pulled out to the outside of the main body of the copying machine and then the upper frame is pulled out. Lift and rotate the transport section. When the upper transport unit is swung upward with respect to the lower transport unit by a predetermined distance, the link member locks the upper transport unit and the lower transport unit at the spacing. This makes it possible to remove the jammed paper between the upper conveyance unit and the lower conveyance unit. When the upper transport unit is further lifted and swung, the lower transport unit connected via the link member also swivels, so that the upper side of the sheet storage unit is opened and the sheet jammed in the sheet storage unit can be removed.

[0005]

In the copying machine equipped with the sheet transporting device constructed as described above, the space between the upper transporting guide and the lower transporting guide used when forming images on both sides is clogged. The jam processing for removing the paper can be performed by pulling the main body frame outside the main body of the copying machine, as described above. However, the above copying machine has the following problems. (1) An image forming conveyance path arranged above the paper conveyance device in the main body of the copying machine, and arranged so as to extend substantially tangentially to the outer peripheral surface of the photosensitive drum. If a paper jam occurs in the image forming transport path for forming an image on one side, the image forming transport path will not be opened even if the main body frame is pulled out of the copier body. Therefore, it is not possible to perform jam processing on the image forming conveyance path. In addition, since the drawing-out direction of the main body frame is the direction (front-back direction of the copying machine main body) which is orthogonal to the paper conveying direction (transverse direction when the copying machine main body is viewed from the front), when the main body frame is pulled out, the paper The paper may be torn (for example, when the paper exists across the conveyance path on the copying machine main body side and the conveyance path on the main body frame side). (2) With the main body frame pulled out of the main body of the copying machine, the entire paper storage section between the upper conveyance guide and the lower conveyance guide and below it is covered by the upper conveyance guide and the like. . For this reason, it is not possible to visually check in which part the paper is jammed in the state where the paper is simply pulled out, so it takes time to search for the jammed paper. (3) When performing the jam processing, it is necessary to completely pull out the main body frame from the main body of the copying machine regardless of the jammed state.

An object of the present invention is not only jam processing for removing paper jammed in the return path and the reverse conveyance path used when images are formed on both sides, but also an image formation conveyance path for forming an image on one side. Jam processing that removes jammed paper in the upstream area of the
A new image forming apparatus is provided.

Another object of the present invention is to provide a novel image forming apparatus which enables jam processing without breaking the paper.

Still another object of the present invention is to provide a novel image forming apparatus which enables jam processing without completely pulling out the transport unit from the apparatus main body.

Still another object of the present invention is to form an image on one side as well as a sheet jammed in a return path and a reverse conveyance path used when forming an image on both sides during jam processing. It is an object of the present invention to provide a novel image forming apparatus that makes it possible to easily visually check even a sheet jammed in the upstream side region of the image forming conveyance path.

[0010]

According to the present invention, an apparatus main body having a photosensitive drum, a conveying unit mounted on the apparatus main body, and a sheet conveying path are provided, and the sheet conveying path is
An image forming conveyance path in which an image is formed on one side of a conveyed sheet, a reverse conveyance path in which the conveyance direction of a sheet selectively introduced from the downstream of the image formation conveyance path is reversed, and a reverse conveyance path is reversed conveyance. The returned paper is returned below the image forming conveyance path with the front and back facing in the same direction, and the paper returned through the returning path is turned upside down and reintroduced upstream of the image forming conveyance path. In the image forming apparatus having a conveyance path, the return path and the reverse conveyance path are formed in the conveyance unit, and the conveyance unit is attached to the apparatus main body so as to be pulled out in the upstream direction of the image formation conveyance path. In the state in which is mounted, an upstream region of the image forming transport path is formed between the upper surface of the transport unit and the corresponding lower surface of the apparatus body, and the entire sheet transport path is continuous.
When the transport unit is pulled out, the upstream area of the image forming transport path and the side of the return path and the side of the reversing transport path formed in the transport unit are opened. A device is provided.

The transport unit is composed of a unit main body and an auxiliary unit. One end of the auxiliary unit on the side opposite to the drawing direction is rotatably attached to one end of the transport unit on the side opposite to the drawing direction. When the auxiliary unit is mounted, the return path and the reverse conveyance path are formed between the auxiliary unit and the transport unit, and when the transport unit is pulled out and the other end of the auxiliary unit is swung upward,
It is preferable that the return path and the reverse transfer path formed in the transfer unit are opened.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of an image forming apparatus constructed according to the present invention will be described below in more detail with reference to the accompanying drawings.

Referring to FIG. 1, numeral 100 indicates a laser printer (hereinafter simply referred to as "printer") which is an image forming apparatus, and the printer 100 is a printer which is a main body of the image forming apparatus in a rectangular parallelepiped shape. The main body 102 and the transport unit 2 that is detachably attached to the printer main body 102
00 and a sheet transport path including each transport path described later. The transport unit 200 includes a unit body 210,
It is composed of an auxiliary unit 220 mounted on the unit main body 210 so as to be rotatable. Printer body 102
The paper feed cassette 40 is mounted below the transport unit 200 so as to be drawn out in a direction orthogonal to the paper transport direction. Hereinafter, the configuration of the printer 100 with the transport unit 200 mounted (accommodated) in the printer body 102 will be described.

In the printer main body 102, an image forming means 10 having a known structure is disposed.
The image forming unit 10 includes a photoconductor drum 11, a main charger 12, a developing device 13, which is arranged around the photoconductor drum 11.
Image forming elements such as a transfer roller 14 (or a transfer charger not shown) serving as a transfer unit, a cleaner 15, and a neutralizer not shown are provided. The image forming unit 10 is also disposed at an upper position in the printer body 102, converts the input image information into laser light, and irradiates the surface of the photosensitive drum 11 via the mirror 16 with a laser scanning unit LSU. Is equipped with.

Also in the printer body 102, an image forming and conveying path 20 in which an image is formed on one side of a sheet to be conveyed.
The reverse conveyance path 22 in which the conveyance direction of the sheet selectively introduced from the downstream of the image formation conveyance path 20 is reversed, and the sheet reversely conveyed from the reverse conveyance path 22 is the image formation conveyance path 20.
Return path 24 that returns the lower part of the sheet with the same orientation of the front and back sides.
And a reversal conveyance path 26 in which the sheet returned through the return path 24 is turned upside down and is re-loaded into the upstream side of the image forming conveyance path 20. In this embodiment, the image forming conveyance path 20 extends from the one side surface (left side surface in FIG. 1) of the printer main body 102 to the other side surface (right side surface in FIG. 1) at a substantially central portion in the vertical direction in the printer main body 102. It is composed of an upstream region 20a that extends substantially horizontally and a downstream region 20b that flips upward from the downstream end of the upstream region 20a. To be more precise, the upstream side region 20a of the image forming conveyance path 20 extends gradually downward from the upstream end toward the downstream side so that the lowermost end position of the surface of the photosensitive drum 11 extends substantially horizontally in the tangential direction. It is arranged so as to extend obliquely to and to be inclined slightly upward at the downstream end. The upstream area 20a of the image forming conveyance path 20 is also the printer body 10 when the printer 100 is viewed from the front (when viewed from the front to the back of the paper in FIG. 1).
It can be said that it extends almost horizontally in the lateral direction of 2.

At a position upstream of the photosensitive drum 11 in the upstream side area 20a of the image forming and conveying path 20, the paper feed roller pair 30 (strictly, the separation roller pair 30 is provided from the upstream end to the downstream side. ) And a pair of registration rollers 31 are arranged in this order, and the transfer roller 14 is arranged in contact with the surface of the photoconductor drum 11 at a position corresponding to the photoconductor drum 11. In the image forming conveyance path 20,
A fixing device 32 is arranged in a position downstream of the photosensitive drum 11 and in the downstream region 20b. A fixing roller pair 32A including a fixing roller and a pressure roller is arranged at an upstream position in the fixing device 32, and a conveying roller pair 32B is arranged at a downstream position in the fixing device 32. The discharge roller pair 33 is arranged at the downstream end position of the image forming conveyance path 20, that is, at the downstream end position of the downstream region 20b. At the upper end of the printer body 102, a paper discharge tray 34 for stacking the paper discharged by the discharge roller pair 33 is arranged. The discharge roller pair 33 also has a function of reversely conveying the sheet having the image formed on one surface toward the reverse conveyance path 22 when forming the image on the other surface of the sheet having the image formed on one surface. Therefore, it is configured such that it can rotate in the normal and reverse directions. The reverse transport path 22 is provided in the downstream side area 20 of the image forming transport path 20.
In b, the position is downstream from the fixing device 32 and upstream from the discharge roller pair 34, and
It is arranged so as to curve and extend toward the upstream direction of the image forming conveyance path 20. A reverse rotation conveyance roller pair 35 is arranged at the downstream end position of the reverse rotation conveyance path 22.

The return path 24 and the reversal transfer path 26 are formed in the transfer unit 200. The upstream end of the return path 24 is positioned so as to be substantially continuous with the downstream end of the reverse rotation transport path 22, and the downstream end of the return path 24 is disposed so as to be continuous with the upstream end of the reverse transport path 26. Further, the downstream end of the reversing conveyance path 26 is arranged so as to join the position on the upstream side of the registration roller pair 31 and on the downstream side of the paper feed roller pair 30 in the upstream area 20 a of the image forming conveyance path 20. There is. A return roller pair 36 is arranged in the return path 24. A switching claw C for switching the conveyance direction of the sheet is provided at the confluence of the reverse conveyance path 26 and the upstream area 20a of the image forming conveyance path 20. The manual feed tray 2 is provided at one end of the transport unit 200 on the pull-out direction side.
00a is attached. The bypass tray 200a is
The image forming conveyance path 20 is mounted so as to further extend in the upstream direction from the upstream end in the upstream area 20a. The transport unit 200 is also provided with a paper feed transport path 37 extending substantially vertically. The upstream end of the paper feed transport path 37 is arranged so as to be substantially continuous with the downstream end of a paper feed transport path 38, which will be described later, disposed in the printer body 102, and the downstream end of the paper feed transport path 37 is inverted. Transport path 26
It is arranged so as to join the upstream area of the. A pair of sheet feeding / conveying rollers 39 is arranged at the upstream end position of the sheet feeding / conveying path 37.

At the lower end of the printer body 102,
At a position lower than the transport unit 200, the paper feed cassette 40 is mounted so as to be freely drawn out. Paper feed cassette 40
A sheet mounting table 41 is disposed inside so as to be rotatable around one end, and the other end is biased upward by a compression coil spring 42. A paper feed roller 43 is arranged at a lower end position in the printer body 102 and an upper position at the other end of the paper placement table 41. Paper stand 41
The positional relationship between the uppermost sheets of the stacked sheets is regulated so that the upper surface of the leading edge of the sheet is pressed against the sheet feeding roller 43 by the spring force of the compression coil spring 42. At the lower end of the printer body 102, on the downstream side of the paper feed roller 43, the paper feed conveyance path 38 is arranged so as to extend upward and incline in the downstream direction of the image forming conveyance path 20. Has been done. The upstream end of the paper feed transport path 38 is
It is arranged immediately downstream of the paper feed roller 43, and has a paper feed conveyance path 3
The downstream end of No. 8 is arranged so as to be continuous with the upstream end of the above-described paper feed conveyance path 37 arranged in the conveyance unit 200.

With reference to FIGS. 1 to 4, the transport unit 20
0 is composed of a unit main body 210 and an auxiliary unit 220, and is attached to the printer main body 102 so as to be drawn out in the upstream direction (left side in FIG. 1) of the image forming conveyance path 20. The upstream direction of the image forming transport path 20 and the pull-out direction of the transport unit 200 substantially match, and the downstream direction of the image forming transport path 20 and the transport unit 200.
The direction substantially opposite to the pull-out direction, that is, the insertion direction. The unit main body 210 includes a pair of side plates 212 extending in parallel with each other with a space therebetween.
And a guide plate 213 arranged to connect the two. The guide plate 213 is gradually inclined upward in the drawing direction from one end (the right end in FIG. 1) between the side plates 212 on the insertion direction side of the transport unit 200 to form a substantially linear shape. A region 213a that curves slightly upward at the end portion in the direction, and a region 213a
And a region 213b extending downward from the end in the drawing direction to the lower end of each of the side plates 212.
An area 213a of the guide plate 213 defines the lower guide surface of the return path 24, and an area 213b of the guide plate 213 is the paper feed conveyance path 37.
The guide surface on one side of is specified. The upper end of each portion of the side plate 212 where the region 213a of the guide plate 213 exists is defined by the region 213a.

As is apparent from FIG. 3, the upper end of each of the side plates 212 on the pull-out direction side has a guide plate 213.
Is formed so as to be present at a position higher than the upper end of the portion in which is present, and another guide plate 214 is provided at the end portion from the lower end toward the upper end and in the insertion direction (right side in FIG. 1). It is arranged so as to extend while curving. The other curved guide plate 214 is provided on the other side guide surface of the sheet feeding / conveying path 37 and the reverse conveying path 2 continuous with the other side guide surface.
6 defines one side guide surface. Further, another guide plate 215 is arranged at the upper end of each of the side plates 212 at the end portion on the pull-out direction side. The guide plate 215 is arranged so that the upper end of each of the end portions of the side plate 212 extends slightly inclined downward from the end of the end portion in the drawing direction to the end of the end portion in the insertion direction. This guide plate 21
5 defines the lower side of the upstream end of the upstream area 20a of the image forming conveyance path 20. An end plate 216 is arranged upright between the ends of the side plates 212 in the drawing direction. The end plate 216 defines the end surface of the unit main body 210 on the pull-out direction side.

A flange portion 212a extending upward from the upper end of each side plate 212 is formed at one end of each side plate 212 on the insertion direction side. The auxiliary unit 220 is rotatably mounted between the flange portions 212a. The auxiliary unit 220 includes a pair of side plates 222 extending in parallel at a distance from each other, and a guide plate 223 arranged to connect the lower ends of the side plates 222.
A guide plate 225 arranged to connect upper ends of the side plates 222, an end plate 226 arranged to connect ends of the side plates 222 on the insertion direction side, and a side plate 222. And the other end plate 224 disposed so as to connect the ends in the drawing direction. Guide plate 223
Defines the lower surface of the auxiliary unit 220, and the guide plate 225
Defines the upper surface of the auxiliary unit 220, and one end plate 226
Defines the other end surface of the auxiliary unit 220 on the insertion direction side, and the other end plate 224 defines one end surface of the auxiliary unit 220 on the extraction direction side. One end of the side plate 222 of the auxiliary unit 220 on the insertion direction side is rotatably supported between the flanges 212a of the unit body 210 via a shaft 227 arranged on a common axis. There is. With such a configuration, the auxiliary unit 220
Is attached to the unit main body 210 so that the other end can be swung upward. The mounting position where the other end of the auxiliary unit 220 is not turned upward is
It is defined by a releasable locking means arranged between the unit body 210 and the auxiliary unit 220. This locking means is, for example, a side plate 212 of the unit main body 210.
A substantially U-shaped elastic locking clip member (not shown) disposed on the outer side of each of the side plates 2 of the auxiliary unit 220.
Each of the 22 may include a locked pin arranged to extend laterally outward from a corresponding outer position.

As shown in FIG. 2, the guide plate 223 defining the lower surface of the auxiliary unit 220 is in contact with the area 213a of the guide plate 213 of the unit main body 210 when the transport unit 220 is locked at the mounting position. The return path 24 is configured in cooperation. The guide plate 224 that defines the other end surface of the auxiliary unit 220 cooperates with the guide plate 214 of the unit main body 210 to form the reverse conveyance path 26. Also,
A guide plate 225 that defines the upper surface of the auxiliary unit 220
Are positioned on the extension of the upper surface of the guide plate 215 of the unit body 210. The upper surface of the guide plate 225 is formed so as to gradually incline downward from the end in the drawing direction toward the insertion direction and incline slightly upward at the end in the insertion direction. The one roller 30a forming the paper feed roller pair 30 is disposed on the guide plate 215 of the unit main body 210, and the one roller 31a forming the registration roller pair 31 is the auxiliary unit 2
20 is arranged on the guide plate 225, and the transfer roller 14 is arranged on the guide plate 225 of the auxiliary unit 220.
The other roller 30b constituting the paper feed roller pair 30 and the other roller 31b constituting the registration roller pair 31.
Is a guide plate 1 of the printer body 102, which will be described later.
It is arranged at 08. Further, one roller 36a constituting the return roller pair 36 is arranged on the guide plate 213a of the unit main body 210, and the other roller 36b constituting the return roller pair 36 is arranged on the guide plate 223 of the auxiliary unit 220. Has been done.

The printer body 102 includes a transport unit 2
A storage space 104 (see FIGS. 2 to 4) is formed so that 00 can be inserted and pulled out from one side of the printer body 102. 2 to 4, the printer main body 102
Is provided with a pair of side plates 106 arranged so as to extend in parallel with each other at intervals, and a guide plate 108 is arranged between the side plates 106. An upright plate 109 is provided at an end portion between the side plates 106 on the side opposite to the one side of the printer body 102.
Is provided. Side plate 106 of printer body 102
An accommodation space 104 is formed in a region below the guide plate 108, which is surrounded by the guide plate 108 and the upright plate 109. The rear end of the accommodation space 104 (the rear end on the insertion direction side)
Is defined by the upright plate 109. Transport unit 200
Side plate 212 of the unit main body 210 and the printer main body 1
A guide rail means (or a slide rail means) 110, which may have a known structure per se, is arranged between the No. 02 and the corresponding side plate 106. Transport unit 20
0 is a housing position (see FIG. 1) housed in the housing space 104 of the printer main body 102 via the guide rail means 110, and a withdrawal position where most of the housing space 104 is withdrawn (see FIGS. 2 and 3). ) Is mounted to be movable between.

The accommodation position of the transport unit 200 is defined by a releasable locking means (not shown) which is arranged between the transport unit 200 and the printer main body 102 and may have a known structure. . The locking means is composed of, for example, a locking hole provided in the upright plate 109 of the printer main body 102 and a locked rod arranged at a corresponding position at the end of the transport unit 200 in the insertion direction of the transport unit 210. You can Further, the pulling-out position of the transport unit 200 is defined by the stop means (not shown) which is disposed on the guide rail means 110 and may have a known structure per se. Further, it is preferable in terms of maintenance that the transport unit 200 can be completely removed from the printer main body 102 by slightly lifting the transport unit 200 with respect to the guide rail means 110 (such a removable structure is also known. is there).

In the carrying unit 200, the auxiliary unit 220 is locked in the mounting position, and the carrying unit 200 is housed in the printer body 102 (see FIG. 1).
The upper surface of the guide plate 215 of the printer 10 and the upper surface of the guide plate 225 of the auxiliary unit 220 cooperate with the guide plate 108, which is the corresponding lower surface of the printer body 102, to form the image forming conveyance path 20, more specifically, the image forming conveyance path. The upstream region 20a of 20 (that is, the upstream region 20a existing upstream of the fixing device 32) is formed. Further, the upstream side area 20 a in the image forming conveyance path 20 and the printer body 10
2, the downstream side region 20b formed in 2, the transport unit 200
The return path 24 formed in the printer main body 102, the reverse conveyance path 22 formed in the printer main body 102, the paper feed conveyance path 37 formed in the conveyance unit 200, the paper feed conveyance path 38 formed in the printer main body 102, and the conveyance unit 200. The formed reverse conveyance path 26 and the upstream region 20a of the image formation conveyance path 20 are made continuous with each other. As a result, all the paper transport paths, that is, the entire paper transport path, are made continuous so that the paper can be transported.

Next, the printer 1 configured as described above
The printing operation of No. 00 will be briefly described. Referring to FIG. 1, in the normal single-sided print mode, the switching claw C is positioned at the position indicated by the solid line. The paper fed from the paper feed cassette 40 in response to the input of the print start signal passes through the paper feed conveyance path 38, the paper feed conveyance path 37, the reversal conveyance path 26, and the upstream area 20 a of the image forming conveyance path 20 to the photosensitive drum. An image is formed on one surface of the sheet while being conveyed so as to pass through the transfer area 11 and the fixing device 32. The paper on which the image is formed on one side is discharged onto the paper discharge tray 34 by the discharge roller pair 33. Further, in the case of the normal double-sided print mode, the paper on which the image is fixed on one side as described above is the downstream area 20b of the image forming conveyance path 20.
In the above, the discharge roller pair 33 is switched back to the reverse conveyance path 22 with the front and back sides in the same state. The switched-back paper is fed from the reverse transport path 22 to the return path 2
4 and the reversing conveyance path 26, the front and back are reversed and the sheet is re-conveyed to the image forming conveyance path 20. After the image is formed on the other surface of the sheet as described above, the sheet ejection tray 34
Discharged on top.

When paper is supplied from the manual feed tray 200a for printing, the switching claw C is switched to the position indicated by the chain double-dashed line by the ON operation of a solenoid (not shown). In the single-sided print mode, with the switching claw C switched to the position shown by the chain double-dashed line, the paper is fed by the pair of paper feed rollers 30 to the upstream area 2 of the image forming conveyance path 20.
The image is formed on one side as described above, and then discharged onto the discharge tray 34. Further, in the double-sided print mode, the sheet on which the image is fixed on one side as described above is switched to the reverse conveyance path 22 in the downstream area 20b of the image formation conveyance path 20 by the discharge roller pair 33 with the front and back sides being the same. Backed up. The sheet that has been switched back is turned upside down as described above and is re-conveyed to the image forming conveyance path 20, and after the image is formed on the other surface of the sheet, the sheet is ejected from the sheet ejection tray 3
4 is discharged on. The switching claw C is returned to the position indicated by the solid line in advance before the leading edge of the sheet on one side of which the image is formed reaches the upstream area 20a of the image forming and conveying path 20 from the reverse conveying path 26.

When a paper jam occurs in the return path 24, the reverse conveyance path 26, or the upstream area 20a of the image forming conveyance path 20, the conveyance unit 200 accommodated in the accommodation position.
Is pulled out from the storage position to the pull-out position outside one side of the printer body 102 (see FIG. 2). Transport unit 200
When the sheet is pulled out from the accommodation position to the withdrawal position, the accommodation space 104 of the transport unit 200 in the printer body 102 is opened, so that the lower side of the guide plate 108 constituting the upper side of the upstream area 20a of the image forming transport path 20 is located below. It will be released. In addition, the upstream side region 20 of the image forming conveyance path 20
Guide plate 2 of the transport unit 200, which constitutes the lower side of a
The entire upper surfaces of 15 and 225 are opened above the pulled-out transport unit 200. As a result, it becomes possible to easily visually confirm whether or not a paper jam has occurred in the upstream area 20a of the image forming conveyance path 20. As a result, the time for finding the position of the paper jam is shortened, and the total jam processing time can be shortened. Moreover, the upstream area 2 of the image forming conveyance path 20
If the paper jam occurs at 0a, the upstream area 20a can be exposed and the paper can be taken out even if the transport unit 200 is partially pulled out without being completely pulled out. Can be done. In addition, the transport unit 200
Since the paper is pulled out in the same direction as the paper conveyance direction, the paper is not broken, and therefore the jam processing is facilitated.

Furthermore, since the return path 24 and the reversal transfer path 26 formed in the transfer unit 200 can be seen from the side of the pulled out transfer unit 200, the return path 2
4 and whether or not a paper jam has occurred in the reverse conveyance path 26 can be easily confirmed visually. As a result, the time for finding the position of the paper jam is shortened, and the total jam processing time can be shortened. Further, when a paper jam has occurred in the return path 24 and the reverse conveyance path 26, in the pulled-out conveyance unit 200, the other end of the auxiliary unit 220 is moved upward by the shaft 2
When it is turned around 27, the return path 24 and the reversal transfer path 26 formed in the transfer unit 220 are widely opened (see FIG. 3), so that the jam processing can be performed very easily. After jam handling or maintenance,
By turning the auxiliary unit 220 in the opposite direction,
The auxiliary unit 220 can be attached to the original position in the unit main body 210.

As described above, the guide plate 108 of the printer main body 102 and the guide plate 21 of the transport unit 200.
5 and 225, the upstream side region 20a of the image forming conveyance path 20 extends so as to gradually incline downward from the upstream end toward the downstream side and incline slightly upward at the downstream end. It is arranged. With this configuration, when the transport unit 200 is pulled outward from the printer main body 102 to one side, the one roller 30a, 31a and the transfer roller 14 arranged in the transport unit 200 are pressed against each other. It is smoothly separated from the surfaces of the rollers 30b and 31b and the photosensitive drum 11. On the contrary, when the transport unit 200 is pushed into the storage space 104 of the printer body 102 in the insertion direction and is positioned at the storage position, the one roller 30a, 31a and the transfer roller 14 arranged in the transport unit 200 are The rollers 30b and 31b, which are separated from each other, and the surface of the photoconductor drum 11 are smoothly pressed against each other, so that defects such as mutual damage can be surely avoided.

As described above, by pushing the carrying unit 200 into the housing space 104 of the printer body 102 after the jam processing or the maintenance is completed, the carrying unit 200 can be easily positioned at the original housing position.

FIG. 5 shows another embodiment of the printer 100 according to the present invention. In the embodiment of the printer 100, the paper feed cassette 40 is the printer body 1
02 is mounted in the same direction as the transport unit 200 so as to be pulled out independently of the transport unit 200. The sheet cassette 40 is integrally provided with a sheet mounting table 41, a compression coil spring 42, a sheet feeding roller 43, and the like. The paper feed cassette 40 is
It is supported so as to be able to be pulled out through guide rail means (or slide rail means) (not shown) which itself may have a known structure. The paper feed cassette 40 has a housing position (see FIG. 5) housed in the housing space of the printer main body 102 and a drawer position (not shown) in which most of the paper housing cassette is housed through the guide rail means. You can move between them. The two-dot chain line in FIG. 5 shows a state in which a part of the paper feed cassette 40 is pulled out from the accommodation space of the printer body 102. The storage position of the paper feed cassette 40 is defined by a releasable locking means (not shown) which is disposed between the paper feed cassette 40 and the printer body 102 and may have a known structure. Further, the pull-out position of the paper feed cassette 40 is defined by stop means (not shown) which is disposed on the guide rail means and which may have a known structure per se. Further, by slightly raising the paper feed cassette 40 with respect to the guide rail means, the printer body 10
From the viewpoint of maintenance, it is preferable that the device can be completely removed from the device 2 (such a detachable structure is also known).

Other configurations in the embodiment of the printer 100 shown in FIG. 5 are substantially the same as the embodiment of the printer 100 described with reference to FIGS. 1 to 4, so that the same parts in FIG. The same reference numerals are used and the description is omitted. In the embodiment of the printer 100 shown in FIG. 5, in addition to the transport unit 200, the paper feed cassette 40
Also, since it can be pulled out from the printer body 102 in the same direction as the transport unit 200 independently of the transport unit 200, the jam processing can be performed from one direction, and the jam processing can be performed more effectively and efficiently. It becomes possible to do it, and it becomes more convenient in practice.

FIG. 6 shows still another embodiment of the printer 100 according to the present invention. This printer 100
5, the paper feed cassette 40 is attached to the printer body 102 so that it can be pulled out in the same direction as the transport unit 200 independently of the transport unit 200. Is the same. However, when the transport unit 200 is pulled out from the printer body 102, the paper feed cassette 40 is also configured to be pulled out from the printer body 102 integrally with the transport unit 200 in conjunction with this, and this point is shown in FIG. This is different from the embodiment. Paper feed cassette 40
Is a storage position stored in the storage space of the printer body 102 via a guide rail means (not shown) (see FIG. 6).
And a pull-out position (see FIG. 7) in which most of it is pulled out from the accommodation space. When the transport unit 200 is pulled out from the printer body 102 to the pull-out position, the paper feed cassette 40 is also pulled out from the printer body 102 together with the transport unit 200 to the pull-out position (see FIG. 8).

The embodiment of the interlocking mechanism arranged between the transport unit 200 and the paper feed cassette 40 is a step formed at the upper end of the paper feed cassette 40, as clearly shown in FIGS. The portion 44 and the locking projection 244 formed on the transport unit 200 are included. As shown in FIG. 6, when both the paper feed cassette 40 and the transport unit 200 are positioned at the storage position, the locking projection 244 of the transport unit 200 causes the step portion 44 of the paper feed cassette 40 to move in the above-mentioned pulling direction. It is positioned close to the back side of. That is, the stepped portion 44 of the paper feed cassette 40 is
00 is located at an interfering position on the movement locus of the locking projection 244 in the pull-out direction. Therefore, when the paper feed cassette 40 is pulled out from the printer main body 102 in a state where both the paper feed cassette 40 and the transport unit 200 are positioned at the accommodation position, the stepped portion 44 of the paper feed cassette 40 has the stepped portion 44 of the transport unit 200. Since it is separated from the locking protrusion 244,
Only the paper feed cassette 40 is pulled out independently of the transport unit 200. Further, when the transport unit 200 is pulled out from the printer main body 102 in a state in which both the paper feed cassette 40 and the transport unit 200 are positioned at the accommodation position, the locking protrusion 244 of the transport unit 200 causes the lock protrusion 244 of the paper feed cassette 40 to move. Since the sheet feed cassette 40 abuts the stepped portion 44 (interferes with it), the sheet feeding cassette 40 is pulled out together with the transport unit 200.

The other configuration of the printer 100 shown in FIG. 6 is substantially the same as that of the printer 100 described with reference to FIGS. 1 to 4. Therefore, in FIG. The same reference numerals are used and the description is omitted. In the embodiment of the printer 100 shown in FIG. 6, in addition to the transport unit 200, the paper feed cassette 40
Can be pulled out independently of the transport unit 200 in the same direction as the transport unit 200 with respect to the printer body 102.
When pulled out from 02, the paper feed cassette 40
Also, since jamming is carried out together with the transport unit 200 from the printer main body 102, jam handling becomes easier. In addition, the lower part of the upstream side region 20a of the image forming conveyance path 20 is exposed more widely by the roller that pulls out the conveyance unit 200, so that the jam processing becomes easier. Furthermore, as in the embodiment of the printer 100 shown in FIG. 5, the jam processing can be performed from one direction, so that the jam processing can be performed effectively and efficiently, which is practically convenient. Becomes

In the embodiment of the printer 100 shown in FIG. 6, the transport unit 2 in the printer body 102 is used.
The paper feed cassette 40 is attached to the position lower than 00 so as to be drawn out in the same direction as the transport unit 200 independently of the transport unit 200, and the transport unit 200 and the paper feed cassette 40 are interlocked. A mechanism (an interlocking mechanism constituted by the step portion 44 and the locking protrusion 244) is provided,
When the transport unit 200 is pulled out from the printer main body 102, the paper feed cassette 40 is also pulled out together with the transport unit 200 via the interlocking mechanism.
There is also another embodiment in which is mounted (accommodated) so that it can be drawn out in the same direction as the transport unit 200. According to this embodiment, when the transport unit 200 is pulled out from the printer main body 102, the paper feed cassette 40 also moves.
In the state of being housed in the printer main body 102, it is pulled out together with the transport unit 200. The paper feed cassette 40 is
Even when the transport unit 200 is accommodated in the printer body 102 or the transport unit 200 is pulled out from the printer body 102, it can be pulled out from the transport unit 200. Also in this embodiment, as in the embodiment shown in FIG. 6, the jam processing is facilitated, and the jam processing can be performed effectively and efficiently, which is practically convenient.

[0038]

According to the image forming apparatus of the present invention, not only the jam processing for removing the paper jammed in the return path and the reverse conveyance path used when forming images on both sides,
The jam processing for removing the jammed paper in the upstream area of the image forming conveyance path for forming an image on one side can be easily performed. In addition, it is possible to perform jam processing without breaking the paper. Furthermore, it is possible to perform the jam processing without completely pulling out the transport unit from the apparatus main body. Furthermore, in jam processing, not only the paper jammed in the return path and the reverse conveyance path used when forming images on both sides but also the upstream side area of the image formation conveyance path for forming an image on one side. This makes it easy to visually check paper jammed in paper.

[Brief description of drawings]

FIG. 1 is a sectional view schematically showing the overall configuration of an embodiment of a laser printer configured according to the present invention.

FIG. 2 is a diagram showing another operation mode of the laser printer shown in FIG.

FIG. 3 is a diagram showing still another operation mode of the laser printer shown in FIG.

FIG. 4 is a sectional view taken along the line AA of FIG.

FIG. 5 is a sectional view schematically showing the overall configuration of another embodiment of the laser printer configured according to the present invention.

FIG. 6 is a sectional view schematically showing the entire configuration of still another embodiment of the laser printer configured according to the present invention.

7 is a sectional view showing another operation mode of the laser printer shown in FIG.

FIG. 8 is a sectional view showing still another operation mode of the laser printer shown in FIG.

[Explanation of symbols] 10 image forming means 11 Photosensitive drum 14 Transfer roller 20 Image forming transport path 20a upstream area 20b Downstream area 22 Reversed transport path 24 Return Route 26 Reversed transport path 30 (30a, 30b) Paper feed roller pair 31 (31a, 31b) Registration roller pair 36 Return roller pair 37 Paper feed transport path 39 Paper feed roller pair 40 paper cassettes 46 steps 100 laser printer 102 Printer body 104 accommodation space 200 transport units 210 unit body 220 Auxiliary unit 244 Locking protrusion

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 2H072 AA02 CA01 EA12 EA17 EA18                       JA02 JA04                 3F049 AA04 DA11 DA12 DB05 LA02                       LA05 LA07 LB03                 3F100 AA02 BA14 BA23 BA27 CA11

Claims (2)

[Claims] 1. An apparatus main body having a photosensitive drum, a conveyance unit mounted on the apparatus main body, and a sheet conveyance path, wherein the sheet conveyance path is an image in which an image is formed on one side of the conveyed sheet. The formation conveyance path, the reverse conveyance path in which the conveyance direction of the sheet selectively introduced from the downstream of the image formation conveyance path is reversed, and the sheet conveyed in the reverse direction from the reverse conveyance path is located below the image formation conveyance path. In an image forming apparatus that includes a return path for returning sheets in the same direction, and a reversing conveyance path for reversing the sheet returned through the return path and reloading it upstream of the image forming conveyance path, The return path and the reversal conveyance path are formed in the unit, the conveyance unit is attached to the apparatus main body so that it can be pulled out in the upstream direction of the image forming conveyance path, and the conveyance unit is attached to the upper surface of the conveyance unit. apparatus An upstream area of the image forming conveyance path is formed between the corresponding lower surface of the body and the entire sheet conveying path is continuous, and when the conveying unit is pulled out, the upstream area of the image forming conveyance path and the conveying area are conveyed. An image forming apparatus, wherein a side of the return path and a side of the reverse conveyance path formed in the unit are opened. 2. The transport unit comprises a unit main body and an auxiliary unit, and one end of the auxiliary unit on the side opposite to the drawing direction can be swung to one end of the transport unit on the side opposite to the drawing direction. When the auxiliary unit and the auxiliary unit are attached, the return path and the reversal conveyance path are formed between the auxiliary unit and the conveyance unit, and the conveyance unit is pulled out and the other end of the auxiliary unit is swung upward. The image forming apparatus according to claim 1, wherein the return path and the reverse conveyance path formed in the conveyance unit are opened.