JPH09114152A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reversing path not to interfere with a component so as to stabilize sheet transport by disposing the reversing path in such a manner as to be passed between a paper feeding means and the inside part of the apparatus main body and extended to the lower side of the paper feeding means. SOLUTION: A reversing path H31 comprises a vertical reversing path B31a extended from a pair of reversing rollers 14 to pass between the inside part of a laser beam printer(LBP) main body and a set of paper feed cassettes K1, K2, and a horizontal reversing path H31b which is connected to the vertical reversing path H31a and extended to the lower side of the paper feed cassette K2. The reversing path H1 is provided with sheet guide members 23, 24, the sheet guide member 24 is not extended to a part parallel to the lower surface of the paper feed cassette K2, and the lower surface of the paper feed cassette K2 is functioned as a guide member for a sheet material. Accordingly, at the time of switching back a sheet material for forming images on both sides of the sheet material, the sheet material is not put to the outside of the LBP main body, so that stable transport can be performed without any increase in area required for installation.

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, and more particularly to a sheet material reversing path for an apparatus capable of forming images on both sides.

[0002]

2. Description of the Related Art FIG. 9 shows an image forming apparatus which can form an image on both sides of a sheet material which has been generally used conventionally.

In FIG. 9, S is a sheet material, and K'is a sheet feeding cassette as a sheet feeding means which is detachably arranged at a position below the main body of the apparatus. Reference numeral 1 is a paper feed roller for feeding a sheet material S from a paper feed cassette K ′, 2 is a pair of conveyance rollers provided on a conveyance path of the sheet material S, and 3 is a pair of registration rollers. The route H1 is configured.

Reference numeral G denotes an image forming portion, which forms an image by a well-known electrophotographic method in this conventional example, and the photosensitive drum 4, the transfer roller 5, and the surface of the photosensitive drum 4 are typical constituent elements. There is described a scanner unit 15 which irradiates a laser beam to form a latent image.
Further, 16 is a folding mirror, and 6 and 7 are fixing roller pairs.

Reference numerals 8, 9, and 10 denote conveying roller pairs that are appropriately provided in the sheet material discharge path H2 downstream of the image forming section.

A pair of reversing rollers 14 is provided on a reversing path H3 for reversing the sheet material S and is configured to be rotatable in the forward and reverse directions. The conveyance direction switching means switches to either the material discharge path H2 or the reversal path H3.

The sheet material S which has entered the reversing path H3 is conveyed through the resupply path H4 after the front and back sides are reversed. 11,
Reference numerals 12 and 13 denote conveying roller pairs that are appropriately provided in the resupply path H4.

Next, the operation of conveying the sheet material S will be described. The sheet material S fed from the sheet feeding cassette K ′ by the sheet feeding roller 1 is conveyed to the registration roller pair 3 by the conveying roller pair 2. The conveyance is temporarily stopped by the registration roller pair 3 and is conveyed at the same timing as the toner image formed on the photosensitive drum 4, and the toner image on the photosensitive drum 4 is transferred to a predetermined position of the sheet material S. .

After that, the sheet material S is made up of a pair of fixing rollers 6,7.
Then, the image is fixed there. The sheet material S on which the image has been fixed is conveyed by the conveying roller pair 8 to the conveying direction switching means 17 (hereinafter referred to as a flapper).

When images are formed on both sides of the sheet material S, the sheet material S on which the image formation on the first side is finished is directed by the flapper 17 in the posture shown by the solid line toward the sheet guide member 19 (reversal path H3). Go to. The sheet material S guided to the sheet guide member 19 has a pair of transport rollers 14 that can rotate in the forward and reverse directions.
To switch back and reverse.

At this time, the sheet material S is once conveyed to the outside of the apparatus along the sheet guide member 21 which guides the reversing path H3. Then, the switched back sheet material S is conveyed in the direction of the sheet guide member 20, and is supplied again to the re-supply path H4.
It is guided again to the transport roller pair 2 via the transport roller pairs 11, 12, and 13.

The sheet material S guided to the pair of transport rollers 2 is again transported to the pair of registration rollers 3 and an image is formed on the second surface of the image forming section G in the same manner as the first surface.

The sheet material S on which the image is formed on the second surface (similarly when the image is formed on only one surface) is conveyed toward the sheet guide member 18 by the flapper 17 in the posture shown by the broken line. The sheet material discharge path H2 is conveyed by the pair of conveying rollers 8, 9 and 10 and is ejected onto the sheet material stacking tray 22 at the upper part of the apparatus.

[0014]

However, in the above-mentioned prior art, when the switchback is performed in the reversing path H3 for reversing the sheet material, the sheet material comes out of the apparatus. There was a problem.

First, an installation space larger than the size (installation area) of the main body is required so as not to hinder the conveyance of the sheet material when it comes out of the apparatus. Further, if an object is accidentally placed in the space where it is reversed, there is a high possibility that it will come into contact with the sheet material that has come out of the apparatus to cause a jam, and the stability of sheet material conveyance is lacking.

Further, in the case where a switchback dedicated tray mounted on the apparatus is provided in order to stabilize the conveyance of the sheet material that has come out of the apparatus, an installation space larger than the size of the main body is inevitable. It becomes necessary and causes a cost increase.

The present invention has been made in order to solve the above-mentioned problems of the prior art, and an object thereof is to provide a reversing path for reversing a sheet material inside the apparatus main body, and other conventional means. It is an object of the present invention to provide an image forming apparatus which is provided so as not to interfere with existing components and which can stably convey a sheet material in the reversing path.

[0018]

In order to achieve the above object, according to the present invention, an image forming portion for forming an image on a sheet material and an image forming portion disposed at a position sandwiching the image forming portion in the sheet material conveying direction. The sheet material supply path and the sheet material discharge path, the reversal path connected to the sheet material discharge path for reversing the sheet material, and the sheet material reversed by the reversal path is returned to the sheet material supply path. In an image forming apparatus including a supply path and a sheet feeding unit that is detachably disposed inside the apparatus body and below the image forming unit, the reversing path includes the sheet feeding unit and the apparatus. It is provided so as to extend between the inside of the main body and the lower side of the paper feeding means.

However, it is also preferable that the paper feeding means is a paper feeding cassette that can be attached and detached in the conveyance width direction of the sheet material in the reversing path.

Further, in the reversing path, the lower surface of the sheet feeding means may be used as a guide member for conveying the sheet material.

Further, the lower surface of the sheet feeding means may be provided with ribs which are inclined with respect to the sheet material conveying direction.

Therefore, the sheet material, which is turned over to form an image on both sides, passes between the sheet feeding means and the inner portion of the apparatus body without going out of the apparatus body, and extends to the lower side of the sheet feeding means. It is transported on the extended inversion path.

Further, by using the lower surface of the paper feeding means (or the paper feeding cassette) as a guide member for conveying the sheet material, the reversing path can be released by removing the paper feeding means from the main body of the apparatus.

The inclined angled ribs on the lower surface of the paper feed means
The sheet material is prevented from sticking inside the reversing path, and the sheet material is not hooked when the sheet feeding means is detached from the main body of the apparatus while the sheet material exists inside the reversing path.

[0025]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 shows a sectional structure of a laser beam printer (hereinafter referred to as LBP) as an image forming apparatus according to a first embodiment of the present invention. This LB
P has the same basic configuration as the image forming apparatus described with reference to FIG. 9 in the description of the related art, and an image forming unit G and a sheet material supply path H for supplying a sheet material S to the image forming unit G.
1. A sheet material discharge path H2 for discharging a sheet material on which an image is formed, a reversal path H31, a re-supply path H4, and a sheet feeding cassette K1 as a sheet feeding unit on which the sheet material S is placed.
K2. Further, the sheet feeding cassettes K1 and K2 are arranged at a position lower than the image forming portion G, and are attachable / detachable in the sheet material conveyance width direction.

However, in the present embodiment, the configuration other than the sheet feeding cassette K2 and the reversing path H31 at the time of switchback is the same as the conventional example described in FIG. However, the description is omitted.

In FIG. 1, K2 is a sheet feeding cassette, and K2 is
It is slidably attached to the apparatus main body by two rail portions a and K2b. Further, 25 and 26 are support members for supporting the rail portions of K2a and K2b, respectively.

The reverse path H31 will be described. The reversing path H31 is formed by the reversing roller pair 14 in the present embodiment.
A vertical reversal path H31a that passes between the inside of the LBP device body and the paper feed cassettes K1 and K2, and a horizontal reversal path H31b that extends to the lower side of the paper feed cassette K2 following the vertical reversal path H31a. Has been done. Reference numerals 23 and 24 denote sheet guide members of the reversing path H1. The sheet guide member 24 does not extend to a portion parallel to the lower surface of the sheet feeding cassette K2, and the lower surface of the sheet feeding cassette K2 functions as a sheet material guide member. ing.

Next, the back surface of the sheet feeding cassette K2 will be described with reference to FIG. 2. K2c is one of ribs provided for guiding the sheet material and extending in the sheet material conveying direction.
Reference numeral d denotes one of the oblique ribs extending between the ribs and extending at about 45 ° with respect to the sheet material conveying direction as a rib having an inclined angle.

The operation of conveying the sheet material having the above configuration will be described. When forming an image on the second surface, the sheet material S on which the image formation on the first surface is completed is conveyed by the pair of reversing rollers 14 capable of forward and reverse rotation to the reversing path H31 without being taken out of the machine, and the sheet Proceed between the guide members 23, 24.

When the length of the sheet material S is short, the front end of the sheet material S is switched back in the vertical reversal path H31a between the sheet guide members 23 and 24.

However, when the length of the sheet material S is long, the tip of the sheet material S cannot be switched back only by the vertical reversing path H31a. Therefore, the leading end of the sheet material S reaches the horizontal reversing path H31b existing under the sheet feeding cassette K2 to perform switchback.

At this time, ribs K2c and K2d for sheet guides are provided on the lower surface of the sheet feeding cassette K2 to prevent the sheet material S from sticking. The sheet material S after the switchback is conveyed along the direction of the sheet guide member 20 through the resupply path H4, and the image formation of the second surface is performed and the sheet is discharged as in the conventional example.

Next, the operation of the sheet guide ribs K2c and K2d provided on the lower surface of the sheet feeding cassette K2 will be described.

In order to prevent only the sticking of the sheet material S, the rib extending in the carrying direction is sufficient. However, in the present embodiment, it is possible to remove the sheet feeding cassette K2 as shown in FIG. 3 while the sheet material S is being conveyed on the lower surface of the sheet feeding cassette K2. In this case, the paper feed cassette K2 moves in a direction (conveyance width direction) perpendicular to the conveyance direction of the sheet material S. Then, the sheet material S is relatively moved in the transport width direction with respect to the lower surface of the paper feed cassette K2.

Therefore, the rib K2c for the sheet guide is used.
With just that, there will only be ribs that are perpendicular to the transport direction,
The edge of the sheet material S is apt to be caught and cause a jam. Therefore, in the first embodiment, the oblique rib K2d that is inclined in the direction of about 45 ° with respect to the conveying direction is provided, and the reversing path H31 is provided.
Even if the sheet material S exists inside, the sheet material S can be attached and detached without jamming the sheet material S.

Next, the arrangement of the diagonal rib K2d will be described with reference to FIG.

First, considering only normal conveyance, the sheet material S is first conveyed in the direction of the arrow at the time of switchback.
At this time, the tips Sr and Sl of the sheet material S are inclined ribs K2d.
In order to prevent them from being caught, the arrangement of K2dr and K2dl in FIG. 4 is adopted. This is because when the end of the sheet material S is bent as shown in FIG. 5 and the sheet material S advances along the oblique rib K2d, the end is not rolled up and is raised outside. Therefore, this arrangement is applied to each of the tips Sr and Sl of the sheet material S.

Next, during the switchback, the paper feed cassette K2
The case where the desorption is performed will be described with reference to FIGS. 6 and 7. First, when the paper feed cassette K2 is removed during the switchback, the sheet material S moves forward on the lower surface of the paper feed cassette K2 after the front end Sr and the front end Sl. Therefore, in this case, only the front end Sr may be caught by the oblique rib K2d (FIG. 6). At this time, the tip Sr passes only under the diagonal rib K2dr, and the diagonal rib K2dr also passes through the tip Sr of the sheet material S.
It will not be caught on

Next, when the paper feed cassette K2 is mounted, as shown in FIG. 7, the sheet material S is placed in front of the front end Sl and the front end Sr.
After that, the lower surface of the paper feed cassette K2 is advanced. In this case, it is only the front end Sl that may be caught by the oblique rib K2d. At this time, the tip Sl passes under both of the diagonal ribs K2dr and K2dl. Then, when passing under the oblique rib K2dr, the positional relationship is opposite to the positional relationship shown in FIG. 5, and there is a possibility that the tip Sl is caught. Therefore, in order to avoid the danger, in this embodiment, as shown in FIG. 2, the diagonal ribs K2d have a small number of diagonal ribs K2.
Only dl.

Therefore, according to the first embodiment,
When the sheet material is switched back for forming images on both sides, the sheet material S does not go out of the main body of the LBP, so that stable transportation can be performed without increasing the area required for installation.

When the sheet guide member of the reversing path for switchback is also used as the lower surface of the paper feeding cassette, the reversing path is released by pulling out the paper feeding cassette, and even when the sheet material is jammed inside the reversing path. However, this can be dealt with easily, and the cost of the sheet guide member can be reduced.

Further, even when the paper feed cassette is detached during the switchback, by providing the oblique ribs at an angle of about 45 ° with respect to the conveyance direction, the sheet material is prevented from being caught and the conveyance reliability can be improved.

(Second Embodiment) FIG. 8 shows a second embodiment of the present invention. In FIG. 8, 27 is a sheet guide member provided in the reversing path H31, and other configurations are the same as those in the first embodiment.

The sheet guide member 27 is a sheet feeding cassette K.
The part of the sheet 2 parallel to the lower surface also covers the reversing path H31, so that the sheet material S can be reversed without being affected by the attachment / detachment of the sheet feeding cassette K2.

However, in the case where a jam occurs inside the reversing path H31, the operability will be greatly reduced unless there is a means for releasing the reversing path H31. Therefore, the sheet guide member 23 is placed inside the LBP housing. The opening / closing part 28 is shared with the above.

[0048]

The reversing path of the sheet material of the image forming apparatus to which the present invention is applied is arranged in the main body of the apparatus without interfering with the components conventionally provided. Therefore, since the sheet material S does not go out of the apparatus main body, the area required for installation is not increased, contact with other members of the inverted sheet material is also avoided, and stable conveyance is performed.

Further, when the sheet guide member of the reversing path for switchback is also used as the lower surface of the paper feeding cassette, the reversing path is released by pulling out the paper feeding cassette, and even if the sheet material is jammed inside the reversing path. However, this can be dealt with easily, and the cost of the sheet guide member can be reduced.

Further, by providing the rib on the lower surface of the paper feed cassette at an angle inclined with respect to the carrying direction, it is possible to prevent the sheet material in the reversing path from being caught when the paper feed cassette is attached and detached, and to improve the reliability of the carrying.

[Brief description of the drawings]

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

FIG. 2 is a perspective view of a paper feed cassette according to the first embodiment of the present invention.

FIG. 3 is a diagram showing how the paper feed cassette is attached and detached according to the first embodiment of the present invention.

FIG. 4 is an explanatory diagram of a paper feed cassette according to the first embodiment of the present invention.

FIG. 5 is an explanatory diagram of a state in which the rib and the sheet material of the sheet feeding cassette according to the first embodiment of the present invention are in contact with each other.

FIG. 6 is an explanatory diagram when the sheet cassette is attached / detached according to the first embodiment of the present invention.

FIG. 7 is an explanatory diagram when a sheet feeding cassette according to the first embodiment of the present invention is inserted.

FIG. 8 is a schematic configuration diagram of an image forming apparatus according to a second embodiment of the present invention.

FIG. 9 is a schematic configuration diagram of a conventional image forming apparatus.

[Explanation of symbols]

1 Paper Feed Roller 2,8,9,10,11,12,13 Conveyance Roller Pair 3 Registration Roller Pair 4 Photosensitive Drum 5 Transfer Roller 6,7 Fixing Roller Pair 14 Reversing Roller Pair 15 Scanner Unit 16 Folding Mirror 17 Flapper (Conveyance Direction switching means) 18, 19, 20, 21, 21, 23, 24, 27 Sheet guide member 22 Sheet material stack tray 25, 26 Support member H1 Sheet material supply path H2 Sheet material discharge path H3, H31 Inversion path H31a Vertical direction inversion path H31b Horizontal reversal path H4 Resupply path S Sheet materials K ′, K1, K2 Paper feed cassette (paper feed means)

Claims (4)

[Claims] 1. An image forming unit for forming an image on a sheet material, a sheet material supplying path and a sheet material discharging path arranged at positions sandwiching the image forming section in a sheet material conveying direction, and the sheet material discharging path. A reversal path for reversing the sheet material connected to the sheet reflow path, a resupply path for returning the sheet material reversed by the reversal path to the sheet material supply path, and inside the apparatus main body and below the image forming unit. In the image forming apparatus provided with the sheet feeding unit detachably arranged at the position of, the reversing path passes between the sheet feeding unit and an inner portion of the apparatus main body, and extends to the lower side of the sheet feeding unit. An image forming apparatus, which is provided so as to be extended. 2. The image forming apparatus according to claim 1, wherein the paper feeding unit is a paper feeding cassette that is attachable / detachable in a conveyance width direction of the sheet material in the reversing path. 3. The image forming apparatus according to claim 1, wherein the reversing path uses the lower surface of the sheet feeding unit as a guide member for conveying a sheet material. 4. The image forming apparatus according to claim 1, wherein the lower surface of the sheet feeding unit is provided with ribs having an angle inclined with respect to a sheet material conveying direction.