JP3119845B2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, a printer and a facsimile, and more particularly, to a sheet having an image formed on one side and an image formed on the other side. The present invention relates to an image forming apparatus provided with a sheet re-feeding device for re-feeding sheets.

[0002]

2. Description of the Related Art Conventionally, there is an image forming apparatus such as a copying machine, a printer, a facsimile or the like having a duplex mode for forming an image on both sides of one sheet.

The image forming apparatus has a configuration shown in a schematic front view in a longitudinal section of FIG.

[0004] At the bottom left and right inside the main body 2 of the image forming apparatus 1, deck cases 3a and 3b as sheet stacking means are juxtaposed. Each of the deck cases 3a and 3b can store approximately 1500 small-size sheets, such as A4 size, which are frequently used.

[0005] The sheet P of the right deck case 3a in FIG.
Is supplied / separated by the sheet supply unit 31a, and is guided through a sheet feeding path 5d to a resist introduction path 5b which is a sheet conveyance path.

The sheet P of the deck case 3b on the left side in FIG.
Is supplied / separated by the sheet supply unit 31b and guided to the resist introduction path 5b through the sheet feeding path 5a.
The sheet P guided to the resist introduction path 5b passes through the introduction path 5c and passes through the registration roller 10 to the image forming unit 1.
It is transported to 1. The sheet on which the image is formed by the image forming unit 11 is conveyed to the fixing device 15 by the conveying unit 13. Then, the toner image is fixed on the sheet by the fixing device 15.

A sheet discharge roller 17 is provided downstream of the fixing device 15. Between the fixing device 15 and the sheet discharge roller 17, there is provided a flapper 16 for switching a sheet having an image formed on one surface to a reverse introduction path 18. In the double-side mode, the sheet on which an image has been formed on one side is guided by the flapper 16 to the reversal introduction path 18, reversed by the reversing unit 19, and conveyed to the re-feeding path 20. When the sheet is fed into the re-feed path 20, it is turned over.

Then, the sheet is conveyed through a re-feeding path 20. When the leading edge of the sheet reaches the sheet sensor 20b, the sheet is re-feeded by the sheet sensor 20b.
It is detected that the end of 0 has been reached.

Then, a command is issued from the control means (not shown) to the driving means (not shown) for the re-feeding path, and the sheet sensor 20 is output.
At a standby position 20p several tens mm downstream of b, the driving unit is temporarily stopped so that the sheet is temporarily stopped. afterwards,
The sheet on which an image is formed on one side is joined at a predetermined timing after a new sheet is supplied from the sheet feeding paths 5a and 5b to a junction 5b with the resist introduction path 5b.
After passing through j, it is sent again to the resist introduction path 5b.

Thereafter, the sheet is formed with an image on the other surface in the same manner as when an image is formed on one surface, and is discharged to the outside by a sheet discharge roller 17. Thus, the image forming apparatus 1 shown in FIG. 4 can form an image on both sides of a sheet.

The re-feeding path 20 in the image forming apparatus
Is a stackless (through-pass) type, in which a sheet on which an image is to be formed on one side and a sheet on which an image is to be formed on one side and an image is also formed on the other side are registered by a resist introduction pass. 5b can be fed alternately.

Accordingly, after forming an image on one side, the flapper 16 guides re-feeding of a sheet on which an image is to be formed on the other side, and discharge guide of a sheet having an image formed on both sides. It can be done alternately one by one.

Above the reversing section 19 and the re-feeding path 20, two cassettes 4b and 4a, which are used for large size such as A3 and small size such as A4, are arranged vertically. I have. Approximately 500 sheets are stored in the cassettes 4b and 4a.

[0014]

The reversing section 19
The double-sided unit 21 including the re-feeding path 20 and the sheet feeding path 5a of the left deck case 3b can be independently pulled out to the near side.

Therefore, when a sheet jam occurs, when one of the duplex unit 21 and the sheet feeding path 5a is pulled out to perform the jam processing, the other cannot be pulled out to perform the jam processing.

That is, the conventional image forming apparatus 1 has a problem that the sheet feeding path 5a and the duplex unit 21 cannot be pulled out at the same time.

Further, a standby position 20 for re-feeded sheets
Comparing the arrangement position of the left deck case 3b and the arrangement position of the right deck case 3b with respect to p, the left deck case 3b is farther away, and accordingly, the sheet to be re-fed is stopped. The time gets longer.

Therefore, when copying small-sized sheets of A4 size or the like in thousands of sheets in the left deck case 3b in the left deck case 3b, the image forming apparatus 1 uses the right deck case 3a.
There is also a problem that the processing time is longer than in the case of copying on the inner sheet, and the productivity of double-sided copying by supplying the left deck case 3b is deteriorated.

(Purpose) According to the present invention, the re-feeding path and the sheet feeding path can be simultaneously drawn out, and the time required for the double-sided image processing on the sheet is substantially the same regardless of the sheet storage means. It is an object to provide an image forming apparatus.

[0020]

The above object is achieved by the following image forming apparatus.

An image forming apparatus according to the present invention comprises a plurality of sheet stacking means for stacking sheets, and a plurality of sheets provided for each of the sheet stacking means for conveying the sheets taken out from the sheet stacking means. A sheet feeding path connected to the plurality of sheet feeding paths, and a sheet conveying path for conveying the sheet sent from the sheet feeding path to an image forming unit that forms an image; and the image forming unit. A reversing unit for reversing the sheet on which an image is formed on one surface by the reversing unit; and a re-feeding path for supplying the sheet reversed by the reversing unit to the sheet conveying path. at least one of the feed path, said to join the refeed path, using a portion of the refeed path at a downstream side of the merging portion of the refeed path in common, one to the refeed path Image on the side The made sheet and can wait, and
Merges into the reversing section, the re-feeding path and the re-feeding path
A part of the sheet feeding path is
And made it withdrawable.

[0022]

[0023]

[0024]

[0025]

[0026]

(Operation) The image forming apparatus of the present invention can form images on both sides of a sheet.

A sheet is first sent out from a selected sheet stacking means to form an image on one side, and is sent to an image forming unit via a sheet feeding path and a sheet conveying path. In some cases, the sheet is fed to the image forming unit via a short sheet feeding path, a part of a re-feeding path, or a sheet conveying path. An image is formed on one surface of the sheet sent to the image forming unit.

Thereafter, the sheet is sent to the reversing unit, where the sheet is reversed so that an image can be formed on the other surface, and is again sent to the image forming unit via a re-feeding path and a sheet conveying path.

Finally, the sheet has an image formed on the other surface, and is discharged out of the image forming apparatus.

In the above-described sheet flow, when a sheet is sent to the image forming unit via a short sheet feeding path, a part of a re-feeding path, or a sheet conveying path, a part of the re-feeding path is changed to a sheet feeding path. Reversing section, re-feeding path and re-use
A part of the sheet feeding path that joins the feeding path
Because it is pulled out as a unit, when a jam occurs,
By pulling out the re-feeding path, the sheet feeding path can also be drawn naturally.Compared to the conventional drawing of the maximum feeding path and the sheet feeding path separately,
The jam sheet can be easily removed. Further, if a part of the re-feeding path is also used as the sheet feeding path, the sheet feeding path can be shortened accordingly, and the height of the entire image forming apparatus can be reduced.

Further, in the above-mentioned sheet flow, when a sheet having an image formed on one surface is fed to a sheet conveying path via a reversing section and a re-feeding path, a new sheet is fed from the sheet stacking means. Then, the sheet on which an image is formed on one side is made to wait on the upstream side of the sheet supply path, so that interference with a new sheet is avoided.

[0033]

[0034]

Embodiments of the present invention will be described below.

The same parts as those in the related art are denoted by the same reference numerals, and the description of those parts will be omitted.

(First Embodiment) An image forming apparatus according to a first embodiment will be described with reference to FIG.

At the lowermost position of the main body 102 of the image forming apparatus 101, a plurality of deck cases 3a and 3b capable of storing about 1500 sheets P are arranged in series with the resist introduction path 5b (in FIG. 1, left and right sides). Side by side).

Sheet P after image formation in image forming section 11
The toner image is fixed at the fixing unit 15 through the transport unit 13.

In the case of the double-sided mode, the sheet after fixing is sent to the reverse introduction path 18 by the flapper 16 and
After being inverted at 9, the sheet is fed to the re-feeding path 120.

Sheet P conveyed on re-feeding path 120
Joins the resist introduction path 5b at the junction 5bj and is conveyed to the registration roller 10.

The sheet P supplied from the deck case 3b farthest from the resist introduction path 5b among the plurality of deck cases 3a, 3b disposed below and below the re-feeding path 120 is a sheet feeding path. It is conveyed via 55a.

The sheet feeding path 55a joins the intermediate portion of the re-feeding path 120 at the junction 20j. Therefore, the path from the junction 20j to the junction 5bj of the re-feeding path 120 is shared by both the sheet feeding path 55a and the re-feeding path 120.

A part of the reversing section 19, the re-feeding path 120, and a part of the sheet feeding path 55a can be pulled out as an integrated unit. Therefore, the jam sheet generated in the duplex unit 121 is easily and quickly removed by pulling out the duplex unit 121.

As described above, unlike the conventional sheet feeding path 5a shown in FIG. 4, the sheet feeding path 55a is joined to the re-feeding path 120 and shared with the re-feeding path. The length of the feeding path 55a is shortened, so that the jam processing is facilitated, and the height of the image forming apparatus main body 102 can be reduced.

(Second Embodiment) Next, an image forming apparatus according to a second embodiment will be described with reference to FIG.

The image forming apparatus 201 includes an image forming unit 1
1, a double-sided unit 121, deck cases 3a and 3b, and cassettes 4a and 4b are arranged in the image forming apparatus 201 in order from the top. Therefore, the image shape
The image forming process reduces the sheet conveyance path
Save time and increase image processing efficiency
Swelling.

By arranging the double-sided unit 121 linked to the deck cases 3a and 3b near the lower part of the image forming unit 11 as described above, the path between the deck cases 3a and 3b and the image forming unit 11 is increased. When image processing is performed on a large number of sheets, the image processing efficiency of the image forming apparatus can be improved.

(Sheet Standby Control Unit of Image Forming Apparatus of First and Second Embodiments) Next, in the image forming apparatuses of the first and second embodiments, a control unit for holding a sheet on standby will be described with reference to FIG. explain.

The sheet on which an image is formed on one side is guided to a reversal introduction path 18, reversed by a reversing unit 19, and conveyed to a re-feeding path 120. When the sheet sensor 202b detects the leading edge of the sheet sent to the re-feed path 120, the pickup roller 60 of the deck case 3b
b and the motor 6 of the sheet separation roller pair 61b, 62b
When the sheets 3b, 64b, and 65b are rotating and the sheet P is being fed from the left deck case 3b, the standby control unit 100 sets the motor 66b of the transport rollers 200a and 200b to a predetermined time after the sheet is detected. Stop 67b. As a result, the sheet having an image formed on one surface is stopped at the standby position 202p of about 10 mm upstream of the merging portion 20j and is made to stand by. Therefore, interference between the sheet on the re-feed path 120 and the sheet from the deck case 3b is avoided.

When the feeding of the sheets from the deck case 3b is completed, the standby control means 100 controls the motor 66b,
67b is started, and the transport rollers 200c, 20c
The motors 66a and 67a of 0d are also started to convey the waiting sheet to the junction 5bj.

The sheet from the reversing unit 19 is sent to the re-feeding path 120, and the sheet sensor 201a
Is detected, the pickup roller 60a of the deck case 3a and the motors 63a, 64a, 65a of the sheet separation roller pairs 61a, 62a are rotating, and the sheet P is sent out from the right deck case 3b. After a predetermined time from the detection of the sheet, the control unit 100 controls the motors 66a of the conveying rollers 200c and 200d.
67a is stopped. As a result, the sheet on which an image is formed on one side is about 10 m upstream of the junction 5bj.
The motor stops at the standby position 201p of m and is made to wait. Accordingly, interference between the sheet on the re-feed path 120 and the sheet from the deck case 3a is avoided.

When the feeding of the sheet from the deck case 3a is completed, the standby control means 100 sets the motor 66a,
67a is started, and the waiting sheet is merged into the junction 5b.
j.

The sheet conveyed to the merging section 5bj passes through the resist introduction path 5b, an image is formed on the other surface by the image forming section 11, and the image is fixed by the fixing section 15 to form the image forming apparatus. It is discharged outside.

Accordingly, since the length of the sheet feeding path 55a of the left deck case 3b is shorter than that of the conventional sheet feeding path 5a, the sheet having an image formed on one surface is moved on the re-feeding path 120. The waiting time becomes shorter, and the image forming processing time of the image processing apparatus 1 when forming images on both sides of the sheet can be shortened.

[0055]

According to the image forming apparatus of the present invention, the sheet feeding path of at least one of the plurality of sheet stacking means is joined to the intermediate portion of the re-feeding path, and re-feeding is performed. Since the sheet is shared with a part of the feed path, for example, when a sheet is jammed, it is necessary to separately pull out the re-feed path and the sheet feed path of the sheet stacking means from the image forming apparatus main body. It is possible to easily and quickly remove the jammed sheet.

Further, since it is not necessary to join at least one sheet feeding path to the sheet conveying path, the height of the image forming apparatus main body can be reduced.

Further, since the length of the sheet feeding path to be merged with the re-feeding path is shorter than the length of the conventional sheet feeding path, the sheet having an image formed on one surface cannot be re-feeded. The waiting time on the top is shortened, and the image forming processing time of the image processing apparatus when forming images on both sides of the sheet can be shortened, and the image processing efficiency can be improved.

[0058]

[Brief description of the drawings]

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

FIG. 2 is a vertical sectional side view of an image forming apparatus according to a second embodiment of the present invention.

FIG. 3 is a schematic diagram of a sheet standby control unit of the image forming apparatuses according to the first and second embodiments of the present invention.

FIG. 4 is a front sectional view of a conventional image forming apparatus.

[Explanation of symbols]

 P sheet 3a, 3b Deck case (sheet stacking means) 4a, 4b Cassette 5a Sheet feeding path 5b Resist introduction path (sheet conveying path) 5bj Merging section 5c Introduction path 5d Sheet feeding path 11 Image forming section 19 Reversing section 20j Merging 20p Standby position 55a Sheet feed path 100 Standby control means 101, 201 Image forming apparatus 102, 202 Image forming apparatus main body 120 Refeed path 121 Duplex unit 201b, 202b Sheet sensor (standby means) 201p, 202p Standby position

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B65H 83/00-85/00 B65H 1/00-3/68 B65H 29/58

Claims (1)

(57) [Claims] A plurality of sheet stacking means for stacking sheets, a plurality of sheet feeding paths provided for each of the sheet stacking means, and configured to convey the sheets taken out from the sheet stacking means; A sheet conveyance path connected to a plurality of sheet feeding paths and conveying the sheet sent from the sheet feeding path to an image forming unit that forms an image, and an image formed on one surface by the image forming unit. An image forming apparatus comprising: a reversing unit for reversing the sheet on which the sheet is formed, and a re-feeding path for supplying the sheet reversed by the reversing unit to the sheet conveying path. At least one of the re-feeding paths is joined to the re-feeding path, and a part of the re-feeding path downstream of the junction of the re-feeding path is commonly used, and the re-feeding path is joined to one surface of the re-feeding path. Image formed The reversing section, the re-feeding path and the
A part of the sheet feeding path which joins the re-feeding path
However, it is possible to draw out as an integrated unit.
An image forming apparatus.