JP2001206590A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device simple in the construction of the confluence of various feed passages, compact in size and low in cost. SOLUTION: This image forming device has a plurality of branch feed passages B to F for feeding recording media, a converging mechanism for uniting the branch feed passages B to F to a practically vertically extending converging feed passage A, and a first recording medium feeding means 19 for feeding the recording media delivered in the converging feed passage A to a practically vertically extending main feed passage. The converging mechanism has a fixed branch feed guide 60 for delimiting two branch feed passages B and C converging at the converging feed passage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer material conveying device in an image forming apparatus such as a copying machine or a printer employing an electrophotographic system.

[0002]

2. Description of the Related Art FIGS. 3 and 4 show a black-and-white laser beam printer (LB) using electrophotographic recording as an example of a conventional transfer material transfer device for transferring a transfer material such as a sheet-like transfer material.
P).

In these LBPs, in order to reduce a substantial installation area, a U-shaped type or an S-shaped type in which a sheet path from a transfer material stacking section (sheet feeding cassette) to a sheet discharging section is bent. Many device configurations having the above-mentioned configuration are adopted. (First Conventional Example) The LBP 100 shown in FIG. 3 has a main body paper feed cassette 101a and an optional cassette 101b below the apparatus main body, and a multi-sheet feed tray 102 that can be opened and closed on the front side of the apparatus (right side in FIG. 3). The image forming unit 103 is provided in the apparatus main body to form an image (to transfer a toner image) on a transfer material (hereinafter, referred to as a sheet) P sent from each transfer material stacking unit.

In this LBP 100, FIGS. 3 and 4 (FIG. 3)
As shown in the enlarged view of the converging portion of the conveying path, the sheet P sent out from the main body sheet feeding cassette 101a by the sheet feeding roller 104 can swing by the conveying force of the conveying guides 105, 106, and 108 and the leading end of the sheet P. Is sent to the pair of registration rollers 109 along the flapper 107 provided in the pair, and is abutted along the nip portion of the pair of registration rollers 109 to perform skew removal.

Thereafter, the registration roller pair 109 starts rotating at a predetermined timing, and the sheet P is sent to the image forming unit 103 on which the toner image is transferred.

The sheet P sent to the image forming unit 103
Are a transfer roller 110 and a process cartridge 111
The sheet P is fed to an image transfer section including a photosensitive drum 112 serving as an image carrier inside, and an image is transferred to the sheet P.

The sheet P on which the image has been transferred is conveyed to an image fixing device 113 where the image is fixed, and the fixed sheet P is discharged by a discharge roller 114 to a face-down tray 115 also serving as a top plate of the device.

[0008] When paper is to be fed from the multi-sheet feeding tray 102, the multi-sheet feeding tray 102 is opened and sheets P are stacked. The stacked sheets P are fed to the multi-feed roller 1
The sheet is fed out one by one by the transport guides 108 and 1.
17 and a pair of registration rollers 1 along the flapper 107
09. After that, the main paper cassette 101a
The same conveyance as that of the sheet P is performed.

When paper is fed from the optional paper feed cassette 101b, the sheet P sent out by the paper feed roller 118 is conveyed along the conveyance guide 119 and passes through the conveyance path 120 of the main body paper feed cassette 101a. do it,
The sheet is sent to the pair of registration rollers 109 along the conveyance guides 121 and 122 and the flapper 107. Thereafter, the same transport as the sheet P from the main body paper cassette 101a is performed.

In this LBP 100, a substantially vertical transport path from a paper feed unit such as the main body paper feed cassette 101a, the optional cassette 101b, and the multi paper feed tray 102 to the paper discharge unit is used as a boundary, and the front side of the apparatus (FIG. 1 (right portion in FIG. 1) can be opened by rotating about 90 ° to the right side of the apparatus with respect to the apparatus main body in which the process cartridge 111 and the scanner unit 123 are disposed, about the fulcrum shaft 124 provided on the lower side. It has become.

A multi-sheet feed tray 102, a multi-sheet feed roller 116,
A multi-sheet feeding unit such as a conveyance guide 108, one registration roller 109, a transfer roller 110, an image fixing device 113, and the like are attached.

The front surface of the apparatus is held by a locking means (not shown) in a closed state with respect to the apparatus main body. When the locking means is released, the apparatus is largely opened toward the front of the apparatus substantially at the substantially vertical transport path. can do.

By releasing the front of the apparatus, the process cartridge 109 can be attached to and detached from the mounting portion of the apparatus main body in the direction of the front of the apparatus. Further, processing such as jamming of the sheet P in the middle of the transport path in the apparatus can be easily performed.

(Second Conventional Example) Next, the LBP shown in FIG.
At 130, the sheet path is an S-shaped type,
As in the first conventional example shown in FIGS. 3 and 4, a main paper feed cassette 131 and an optional cassette 132 are provided below the apparatus main body, and an openable / closable multi paper feed tray 133 is provided on the front of the apparatus. The main body is provided with an image forming unit 134 for forming an image on a transfer material (hereinafter, referred to as a sheet) P sent from each transfer material stacking unit.

In this LBP 130, the sheets P sent out from the main body paper cassette 131 by the paper feed rollers 135 are separated one by one by a pair of retard rollers 136, and are conveyed along conveyance guides 137, 138, and 139. After being conveyed to the conveying roller pair 141, it reaches the registration roller pair 142, and is conveyed to the image forming unit 134 and the image fixing device 143.

The sheet P that has exited the image fixing device 143 is conveyed to a conveyance guide 145 by a flapper 144, is inverted by this, is conveyed to a face-down tray 147 using a top plate of the device by a discharge roller 146, and is discharged. .

To feed paper from the multi-sheet feed tray 133, the multi-sheet feed tray 133 is opened, and the sheets P stacked thereon are sent out by the multi-sheet feed roller 148, and the registration roller pair is fed along the conveyance guides 149 and 150. 142
After that, the same conveyance as the feeding of the sheet P from the main body paper cassette 131 is performed.

Feeding from the optional cassette 132
The sheet P sent out by the sheet feed roller 151 is separated one by one by a pair of retard rollers 152, conveyed by a pair of intermediate conveyance rollers 153, passes through a conveyance path 154 in the main body sheet cassette, and is conveyed by a conveyance guide 137. , 140 and the conveyance guides 138, 139, the intermediate conveyance roller pair 14
1 and thereafter the main body paper cassette 131
Is carried out in the same manner as the feeding of the sheet P from.

After the image formation and fixing on the first side of the sheet P, the image forming and fixing operation on the second side is automatically performed by the automatic double-sided mode.
4 is swung to the position indicated by the two-dot chain line in the figure. After the first surface is discharged from the image fixing device 143, it is conveyed to the conveyance paths 155 and 157 of the automatic double-sided conveyance system.

Thereafter, the switchback transport roller pair 15
The sheet P switched back in 6 is sent to the conveyance path 158, and is conveyed to the intermediate conveyance roller pair 141 along the conveyance guides 161 and 138 by the conveyance roller pairs 159 and 160. Thereafter, the sheet P is conveyed in the same manner as the sheet P is fed from the main body sheet cassette 131, and the image is fixed on the second side, and is conveyed to the face down tray 147 using the top plate of the apparatus, and is discharged.

In the LBP having this configuration, a part of the apparatus top plate 162 is opened, from which the process cartridge 163 can be attached and detached diagonally upward and to the right. In addition, measures such as jamming of the sheet P inside the apparatus can be performed. Cartridge 163
Can be done after removal.

In recent years, the colorization of LBP has been advanced,
Various color LBPs are produced. This color LB
In P, miniaturization of the entire apparatus is also important, and as shown in FIG. 6, the image forming section is arranged above a paper feed cassette 151 mounted at the lower part of the apparatus main body to achieve miniaturization. Has been devised.

As shown in FIGS. 6A and 6B, there has conventionally been a multicolor image forming apparatus in which a plurality of photosensitive drums are arranged in a line.

As shown in FIG. 6A, the multi-color image forming apparatus is roughly divided into a horizontal arrangement type image forming apparatus 200A in which a plurality of photosensitive drums are arranged in a horizontal direction, and a vertical arrangement. Of the vertical arrangement type image forming apparatus 200B.

As a feature, the horizontal arrangement type image forming apparatus 200
A is low in height but has a large installation area. Conversely, in the vertical arrangement type image forming apparatus 200B, the installation area can be small but the height is high.

When a desktop printer is considered, the vertical arrangement type having a small installation area is advantageous, but it is important how far the height can be reduced, the configuration of an optional feeder, automatic double-sided image formation, and how to arrange paper paths. The vertical arrangement type multi-color image forming apparatus has not been put to practical use, but only the horizontal arrangement type image forming apparatus 200A has been put to practical use.

[0027]

In the above-mentioned first conventional example, although the paper path is in a substantially vertical direction, it is a black and white LBP of one generation before, and the paper handling such as automatic double-sided image formation is considered. There is no.

Further, upstream of the registration roller pair 109, the main body paper feed cassette 101a and the optional cassette 101,
Although the three transport paths of the multi-feeder join, the transport guides 105, 106, 108, 117, 121, 1
22 has a complicated structure, occupies a large space, and poses problems in terms of cost and miniaturization of the apparatus.

The second conventional example is a black-and-white LBP of an S-shaped path which has been recently implemented, is equipped with an optional cassette 132, an automatic double-sided image forming mechanism, and has a good paper handling. On the upstream side of the intermediate conveyance roller pair 141 of the turn conveyance section in the sheet conveyance direction, the conveyance paths of the main body paper feed cassette 131, the optional cassette 132, and the automatic double-sided image forming mechanism join, and the conveyance guide 13
7,138,139,140,161,
On the downstream side of the intermediate conveyance roller pair 141 in the sheet conveyance direction, the conveyance paths from the multi-feeder 133 join, and conveyance guides 149 and 150 are arranged, which has a complicated configuration as in the first conventional example.

In other words, in the above-described conventional example, a C-shape is formed on the upstream side of the pair of conveying rollers or the pair of registration rollers arranged such that the confluence of the various conveying paths is substantially in the conveying direction. It is configured by stacking transport guides, and thus occupies a complicated and large space. The U-shaped conveyance guide is formed with a large curvature.

An object of the invention according to the present application is to provide a low-cost image forming apparatus which is compact in space, simplifies the configuration of a junction of various transport paths, and is compact in space.

[0032]

An image forming apparatus for realizing the object of the invention according to the present invention comprises a plurality of branch transport paths on which recording materials are respectively transported, and the plurality of branch transport paths extend substantially vertically. A merging mechanism for merging with the merging conveyance path, and first recording material conveying means for conveying the recording material conveyed through the merging conveyance path to a main conveyance path extending along a substantially vertical direction; Is characterized in that it has a fixed branch conveyance guide that forms two branch conveyance paths that join at the merge conveyance path. In this image forming apparatus, it is possible to provide a low-cost image forming apparatus which is simplified in configuration of a junction of various transport paths, is compact in space, and has a small space.

In the multi-color image forming apparatus having the vertical arrangement 200B described above, the height direction of the confluence of the various transport paths can be suppressed, and the variety of paper handling can be expanded.

[0034]

1 and 2 show an embodiment of the present invention.

First, the overall configuration of the color image forming apparatus will be outlined with reference to FIG. FIG. 1 is a longitudinal sectional view showing the entire configuration of a full-color laser beam printer 100 which is an embodiment of a color image forming apparatus.

[Overall Configuration of Color Image Forming Apparatus] The color image forming apparatus 100 shown in FIG. 1 includes four photosensitive drums 1a, 1b, 1c and 1d arranged in a vertical direction. The photosensitive drum 1 (1a, 1b, 1c, 1d) is driven to rotate counterclockwise in FIG. A charging device 2 (2a, 2b, 2c, 2d) for uniformly charging the surface of the photosensitive drum 1 in order according to the rotation direction around the photosensitive drum 1, and irradiating the photosensitive drum 1 with a laser beam based on image information. The scanner unit 3 (3a, 3b, 3c, 3) for forming an electrostatic latent image on
d), a developing device 4 (4a, 4b, 4c, 4d) for attaching toner to the electrostatic latent image and developing it as a toner image, and an electrostatic transfer device for transferring the toner image on each photosensitive drum 1 to a transfer material S 5. A cleaning device 6 (6a, 6b, 6) for removing transfer residual toner remaining on the surface of the photosensitive drum 1 after transfer.
c, 6d) and the like.

Here, the photosensitive drum 1, the charging device 2, the developing device 4 and the cleaning device 6 are integrated into a cartridge to form a process cartridge 7.

Hereinafter, the photosensitive drum 1 will be described in detail.

The photosensitive drum 1 is formed by applying an organic photoconductor layer (OPC photosensitive member) to an outer peripheral surface of an aluminum cylinder having a diameter of, for example, 30 mm. The photosensitive drum 1 is
Both ends are rotatably supported by a support member, and are driven to rotate counterclockwise by transmitting a driving force from a driving motor (not shown) to one end.

As the charging device 2, a contact charging type can be used. The charging member is a conductive roller formed in a roller shape.
The surface of the photosensitive drum 1 is uniformly charged by applying a charging bias voltage to the roller while making contact with the surface.

A scanner unit 3 provided for each color is arranged substantially horizontally with respect to the corresponding photosensitive drum 1, and image light corresponding to an image signal is transmitted by a laser diode (not shown) to a scanner motor (not shown). Polygon mirror 9 (9a, 9b, 9c, 9d) rotated at high speed by
Is irradiated. The image light reflected by the polygon mirror 9 is
The surface of the charged photosensitive drum 1 is selectively exposed through the imaging lens 10 (10a, 10b, 10c, 10d) to form an electrostatic latent image.

Each of the developing devices 4a, 4b, 4c, and 4d is composed of a developing device that stores toner of each color of yellow, magenta, cyan, and black.

On the other hand, all the photosensitive drums 1a, 1b, 1
An electrostatic transfer belt 11 that circulates and moves so as to face and contact c and 1d is disposed in the up-down direction.

The electrostatic transfer belt 11 has a resistance of 10 ¹¹ to 10 ¹⁴ Ω ·
It is composed of a film-like member having a thickness of about 150 μm and having a volume resistivity of cm. This electrostatic transfer belt 11
The transfer material S is supported by rollers on four axes in the vertical direction, and the transfer material S is electrostatically attracted by the electrostatic attraction roller 22 and transported on the outer peripheral surface on the left side in the drawing, and is circulated to contact the transfer material S with the photosensitive drum 1. I do. Thereby, the transfer material S is transported to the transfer position by the electrostatic transfer belt 11, and the toner image on the photosensitive drum 1 is transferred.

Abut on the inside of the electrostatic transfer belt 11,
The transfer rollers 12 (12a, 12b, 12c, 12c) are located at positions facing the four photosensitive drums 1a, 1b, 1c, 1d.
d) is juxtaposed. A positive charge is applied to the transfer material S from the transfer roller 12 via the electrostatic transfer belt 11, and an electric field generated by the charge causes the negative toner on the photosensitive drum 1 to be applied to the sheet in contact with the photosensitive drum 1. The image is transferred.

The electrostatic transfer belt 11 has a circumference of about 700 mm,
It is a belt having a thickness of 150 μm. The belt is wound around four rollers of a driving roller 13, driven rollers 14a and 14b, and a tension roller 15, and rotates in the direction of the arrow in the figure. Thus, the toner image is transferred while the transfer material S is conveyed from the driven roller 14a side to the drive roller 13 side by circulating the electrostatic transfer belt 111 described above.

From the main body paper cassette 17 to the paper feed roller 18
The leading end of the transfer material S separated and sent out one by one by the (half-moon roller) abuts the registration roller pair 19, performs skew correction, and then passes through the transfer material leading end detection sensor 41. At this time, the leading end detection signal of the transfer material S is synchronized with the image writing position on the four photosensitive drums 1a, 1b, 1c, 1d, and latent images are formed on the photosensitive drums 1a, 1b, 1c, 1d. Then, a toner image is formed by the developing device 4, the transfer material S is fed to the electrostatic transfer belt 11, and the toner image is sequentially transferred.

The fixing unit 20 fixes the toner images of a plurality of colors transferred to the transfer material S. The fixing unit 20 presses against the rotating heating roller 21a to press and apply heat and pressure to the transfer material S. And a roller 21b.

That is, the transfer material S onto which the toner image on the photosensitive drum 1 has been transferred is conveyed by the fixing roller pair 21 when passing through the fixing unit 20, and is given heat and pressure by the fixing roller pair 21. Thereby, the toner images of a plurality of colors are fixed on the surface of the transfer material S.

In the image forming operation, the process cartridges 7a, 7b, 7c and 7d are sequentially driven in accordance with the print timing, and the photosensitive drum 1 is driven in accordance with the drive.
a, 1b, 1c and 1d are driven to rotate counterclockwise. Then, the scanner units 3 corresponding to the respective process cartridges 7 are sequentially driven.

By this driving, the charging roller 2 applies a uniform electric charge to the peripheral surface of the photosensitive drum 1 and the scanner unit 3
Performs an exposure on the peripheral surface of the photosensitive drum 1 according to an image signal to form an electrostatic latent image on the peripheral surface of the photosensitive drum 1. A developing roller in the developing device 4 transfers (transfers) the toner to a low potential portion of the electrostatic latent image to form (develop) a toner image on the peripheral surface of the photosensitive drum 1.

When the leading end of the toner image carried on the peripheral surface of the photosensitive drum 1 at the most upstream position is rotated and conveyed to a point facing the electrostatic transfer belt 11, printing of the transfer material S is performed on the point. The start detection signal of the transfer material S is synchronized with the start of image writing on the four photosensitive drums 1a, 1b, 1c, 1d so that the start positions coincide.

The transfer material S is pressed between the electrostatic transfer belt 11 and the electrostatic attraction roller 22 by being pressed between the electrostatic transfer belt 11 and the electrostatic attraction roller 22 while being sandwiched between the electrostatic attraction roller 22 and the electrostatic transfer belt 11. A voltage is applied to the transfer material S, which induces electric charge in the dielectric transfer material S and the dielectric layer of the electrostatic transfer belt 11, and electrostatically attracts the transfer material S to the outer periphery of the electrostatic transfer belt 11. are doing. As a result, the transfer material S is stably adsorbed on the electrostatic transfer belt 11, and is conveyed to the most downstream transfer unit.

While being conveyed as described above, the toner image on each photosensitive drum 1 is sequentially transferred onto the transfer material S by the electric field formed between each photosensitive drum 1 and the transfer roller 12.

The transfer material S to which the four color toner images have been transferred is
The electrostatic transfer belt 11 is controlled by the curvature of the belt drive roller 13.
And is carried into the fixing unit 20. Transfer material S
After the toner image is heat-fixed by the fixing unit 20, the toner image is discharged by the discharge roller pair 23 to the face-down tray 24 also serving as the apparatus top plate.

Next, the transfer material S separated from the optional cassette 43 by the paper feed roller 44 one by one and sent out.
The main paper feed cassette 17 is driven by the intermediate conveying roller pair 45.
After passing through the inside conveyance path, it reaches the registration roller pair 19, and thereafter, the same conveyance as the feeding of the transfer material S from the main body paper cassette 17 is performed. Note that a plurality of the main body paper cassettes 17 may be provided.

The multi-tray 46 feeds the paper feed roller 4
The transfer material S separated and sent out one by one by 7 reaches the registration roller pair 19, and thereafter, the same transfer as the transfer of the transfer material S from the main body paper feed cassette 17 is performed.
Note that the sheet feeding roller 18 and the registration roller pair 19 are disposed at substantially symmetric positions with respect to the transfer material conveyance path extending substantially vertically with respect to the registration roller pair 19.

On the other hand, the conveyance path of the second side by the automatic double-sided image conveyance mechanism is as follows.
Is switched back from a predetermined position, and is guided to the transport path 48 along a transport guide (not shown).

Thereafter, the sheet is conveyed substantially vertically downward on the conveyance path 51 by the conveyance roller pairs 49 and 50,
As a result, the sheet is inverted at the upper part of the multi-sheet feeding roller 47 and reaches the registration roller pair 19.

Thereafter, the same conveyance as the feeding of the transfer material S from the main body paper cassette 17 is performed.

Next, the details of the confluence of the various conveyance paths, that is, the confluence of the transfer material at the upstream of the registration roller pair in the transfer material conveyance direction, which is a feature of the present embodiment, will be described with reference to FIG.

In FIG. 2, the transfer material S sent out from the main body paper feed cassette 17 by the paper feed roller 18 is
7, a guide (pre-registration guide) 61 disposed in front of the registration roller via a conveyance guide rib 60b in the substantially vertical direction on the left side of a branch conveyance guide 60 provided substantially vertically below the registration roller pair 19. After the sheet reaches the registration roller pair 19 by the automatic double-sided reversing upper guide 62 arranged substantially opposite to the registration front guide 61, the sheet is conveyed to the electrostatic transfer belt 11 by the conveyance guide 68.

The transfer material S sent out from the multi-tray 46 by the paper feed roller 47 is transferred from the multi-frame transport guide 64 substantially opposed to the transport guide 65 to the branch transport guide provided substantially vertically below the registration roller pair 19. After reaching the registration roller pair 19 by the pre-registration guide 61 and the automatic double-sided reversing upper guide 62 via the transport guide rib 60a in the substantially vertical direction on the right side of 60, the sheet is transported to the electrostatic transfer belt by the transport guide 68.

From the optional cassette 43 to the paper feed roller 4
The transfer material S sent out at 4 is transported by the transport rollers 45 along a transport guide 66 of the main body cassette 17 and a transport guide 67 composed of a multi-frame on the multi-tray 46 side. The registration roller pair 19 is reached by the registration front guide 61 and the automatic double-sided reversing upper guide 62 via the conveyance guide rib 60a in the substantially vertical direction on the right side of the branch conveyance guide 60 provided substantially vertically below and the automatic double-sided reversing lower guide 69. Later, transport guide 6
By 8, it is conveyed to the electrostatic transfer belt 11.

The second side of the transfer material S conveyed by the automatic double-sided image conveying mechanism is reversely conveyed by the conveying roller 52 along the automatic double-sided reversing upper guide 62 and the lower reversing guide 63, and is substantially perpendicular to the registration roller pair 19. After reaching the registration roller pair 19 by the pre-registration guide 61 and the automatic double-sided reversing upper guide 62 via the conveyance guide rib 60a in the right and substantially vertical direction of the branch conveyance guide 60 provided below,
The sheet is conveyed to the electrostatic transfer belt by the conveyance guide 68.

That is, the merging portion is provided immediately below the nip portion of the registration roller pair 19 with the vertical guide portion 61a of the pre-registration guide 61 and the automatic double-sided conveyance upper guide facing the vertical guide portion 61a of the pre-registration guide 61. The vertical guide portion 62 a of 62 forms a merging and conveying path A having a conveying path in the vertical direction, and the wedge-shaped branch conveying guide 60 is directed to the merging and conveying path A with respect to the merging and conveying path A. A first branch transport path B and a second branch transport path C are formed on the left and right of the branch transport guide 60 so as to merge with the merge transport path A.

Further, three branch transport paths D, E, and F join the second branch transport path C formed on the right side of the branch transport guide 60 in the figure.

A semi-circular rib 62a formed in a substantially semi-circular shape downwardly of the automatic double-sided conveyance upper guide 62, and a reversing lower guide 63 arranged with a gap with the semi-circular rib 62a.
Since the third branch conveyance path D, which forms a substantially semi-circular conveyance path by the above, merges with the second branch conveyance path C substantially upward in the vertical direction, FIG.
The transfer material S conveyed through the third branch conveyance path D is joined to the second branch conveyance path C without using a flapper as in the conventional example shown in FIG. It can be transported.

The multi-frame transport guide 64 forming the fourth branch transport path E is inclined with respect to the second branch transport path C having a transport path formed in a substantially vertical direction. Since the upper end of the slope 64 is directed toward the right transport guide rib 60a of the branch transport guide 60, the transfer material S transported through the fourth branch transport path E smoothly joins the second branch transport path C.

Further, as shown in FIG. 2, the fifth branch transport path F is formed in a substantially vertical direction directly below the second branch transport path C, so that the fifth branch transport path F is transported along the fifth branch transport path F. The transferred transfer material S is smoothly transported to the second branch transport path C as it is.

On the other hand, the first branch conveyance path B is formed between the inclined portion 61b of the pre-register guide 61 and the conveyance guide rib 60b on the left side of the branch conveyance guide 60, and is slightly inclined with respect to the vertical direction. And the transport guide 65 of the cassette 17
As a result, the transfer material S whose conveyance direction is directed almost directly upward is guided to the first branch conveyance path B, and is conveyed to the merged conveyance path A without a flapper as in the conventional example.

[0072]

As described above, the present invention has the following effects.

As shown in the conventional example, the confluence of the various conveying paths is formed in a C-shape on the upstream side of the pair of conveying rollers or the pair of registration rollers arranged in a substantially vertical conveying direction. It is composed by stacking transport guides and is complex and occupies a large space.

However, according to the present invention, the image forming apparatus main body cassette (a plurality of cassettes) can be arranged in a substantially vertical upstream direction of the recording material conveyance direction of the transfer material or the like of the conveyance means arranged so as to be in the substantially vertical conveyance direction. ), An optional cassette feeder, automatic double-sided, and multi-feeder, a substantially vertical branch conveyance guide is arranged to guide the transfer material conveyed from at least two conveyance paths to the conveyance means. By adopting a configuration in which the transport paths merge from the side, the configuration of the junction of the various transport paths can be simplified, and a space-compact, low-cost image forming apparatus can be provided.

Further, in the above-described multi-color image forming apparatus having the vertical arrangement 200B, the height direction of the merging portion of the various transport paths can be suppressed, and the variety of paper handling can be expanded.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an inline type multicolor image forming apparatus showing an embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view showing a merging portion of various conveyance paths near a pair of registration rollers in FIG. 1;

FIG. 3 is a main cross-sectional view of a conventional vertical pass type monochrome LBP.

FIG. 4 is an enlarged cross-sectional view showing details of a junction of various transport paths in FIG. 3;

FIG. 5 is a main cross-sectional view of a conventional S-pass type monochrome LPB.

FIGS. 6A and 6B are main cross-sectional views showing the arrangement of a conventional in-line type multicolor image forming apparatus.

[Explanation of symbols]

 Reference Signs List 1 photosensitive drum 3 scanner unit 5 electrostatic transfer belt device 19 registration roller pair 60 branch conveyance guide

Claims (7)

[Claims] A plurality of branch transport paths each of which a recording material is transported; a merging mechanism configured to merge the plurality of branch transport paths with a merge transport path extending in a substantially vertical direction; and a recording medium transported through the merge transport path. And a first recording material conveying means for conveying the material to a main conveyance path extending substantially in the vertical direction, wherein the joining mechanism is configured to form two branch conveyance paths that join at the joining conveyance path. An image forming apparatus having a branch conveyance guide. 2. The multi-branch conveyance path, to which a recording material fed from at least two or more of a paper feed cassette, an optional cassette, an automatic double-sided conveyance mechanism, and a multi-feeder of an image forming apparatus main body is conveyed. The image forming apparatus according to claim 1, wherein 3. A recording material fed from at least one of the automatic double-sided conveyance mechanism and the multi-feeder is conveyed to one branch conveyance path formed on one side of the branch conveyance guide. The image forming apparatus according to claim 2, wherein 4. The apparatus according to claim 1, further comprising a second recording material transport unit provided downstream of the first recording material transport unit in the recording material transport direction in addition to the first recording material transport unit. 1,
4. The image forming apparatus according to 2 or 3. 5. The image forming apparatus according to claim 1, wherein the first recording material conveying means is a pair of registration rollers, and the second recording material conveying means forms an image transfer section or a part of the image transfer section. The image forming apparatus according to claim 4, wherein 6. The image forming apparatus according to claim 2, wherein the branch conveyance path from the automatic double-sided conveyance mechanism is arranged above the branch conveyance path from the multi-feeder. . 7. The image forming apparatus according to claim 2, wherein a branch conveyance path from the optional cassette feeder merges with a branch conveyance path on the multi-feeder side.