Electrophotography – Document handling – Copy
Reexamination Certificate
2002-04-11
2004-04-20
Tran, Hoan (Department: 2852)
Electrophotography
Document handling
Copy
Reexamination Certificate
active
06725011
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image forming apparatus and, in particular, to a construction for discharging sheets with images formed thereon.
2. Related Background Art
In a conventional image forming apparatus, such as a copying machine or a printer, a sheet on which an image has been formed is discharged onto a sheet discharging portion. When discharging a sheet with an image formed thereon with the front and rear surfaces of the sheet reversed, the sheet is reversed by a sheet reversing path before being discharged. This sheet reversing path is also used when performing two-sided printing.
FIG. 15
shows an example of a conventional image forming apparatus having such a sheet reversing path. In this image forming apparatus, a sheet with an image formed thereon is discharged in the direction of the arrow K by discharging rollers
161
. When discharging a sheet after reversing it, a flapper
162
is switched and the sheet with an image formed on the front surface (first surface) thereof is conveyed to a reversing path
167
. Then, reversing rollers
165
are rotated in the reverse direction, and the flapper
162
is restored to the original position.
When forming images on both sides of a sheet, the sheet S
1
with an image formed on the front surface (first surface) thereof is conveyed to the reversing path
167
by way of a conveying roller pair
166
by switching the flapper
162
. Thereafter, when the trailing edge of the sheet passes a flapper
164
provided in the reversing path
167
, the reversing rollers
165
are rotated in the reverse direction, and the flapper
164
is switched, whereby the sheet is fed to an intermediate tray
168
. In this image forming apparatus constructed as described above, the sheet reversing path
167
is arranged perpendicular to the sheet discharging direction.
FIG. 16
shows another example of a conventional image forming apparatus having a sheet reversing path. In this image forming apparatus, the sheet on which image formation has been effected is discharged not to the side of the apparatus main body but to the interior of the apparatus main body.
In this type of image forming apparatus, a sheet contained in a sheet feeding cassette
21
or an option sheet feeding cassette
103
provided as an option is conveyed to an image forming portion
1
by a sheet feeding portion
2
and a toner image is transferred thereto by an electrophotographic process means
150
. Thereafter, the toner image is fixed by a fixing apparatus
151
, and the sheet is conveyed to a sheet discharging portion
4
.
FIG. 17
shows the construction of the sheet discharging portion
4
. As shown in the drawing, this image forming apparatus is equipped with two sheet discharging trays
41
and
42
. The sheet to which the toner image has been fixed is discharged onto the first sheet discharging tray
41
by a first discharging roller
51
, or onto the second sheet discharging tray
42
situated above the first sheet discharging tray
41
by a second discharging roller
52
.
This image forming apparatus is capable of two-sided printing. When performing two-sided printing, a part of the sheet which has passed the fixing apparatus
151
is temporarily discharged onto the first sheet discharging tray
41
by a longitudinal path roller
57
and the first discharging roller
51
. Thereafter, when the trailing edge of the sheet has passed a first flapper
58
, the longitudinal path roller
57
and the first discharging roller
51
are rotated in the reverse direction to convey the sheet to a two-sided path
152
. In this case, the sheet reversing path is the same as the sheet conveying path. Further, the sheet reversing path is perpendicular to the direction of the arrow A in which the sheet is discharged.
Note that the image forming apparatus shown in this drawing functions as both a copying machine and a facsimile apparatus; it is a so-called digital multifunction printer which forms an image by converting the read image information (optical signal) of the original into an electric signal.
In the case of such a multifunction printer, the sheets discharged onto the first and second sheet discharging trays
41
and
42
are rather poor in visibility. Further, it is sometimes required that a sheet conveyed by, for example, a facsimile apparatus should be separately stored. Thus, as shown in
FIG. 18
, for example, a third sheet discharging tray
43
is detachably provided on the outer side surface of the apparatus main body, and the sheet is discharged onto this third sheet discharging tray
43
by a third sheet discharging roller
53
.
When the third sheet discharging tray
43
is thus provided, the sheet to which the toner image has been fixed is discharged onto a third sheet discharging tray
43
by the longitudinal path rollers
54
and
57
and the third discharging roller
53
, with the transfer side being directed upwards.
However, when thus discharging the sheet onto the third sheet discharging tray
43
, the sheet is discharged with the transfer side being directed upwards, so that when the sheet which has been conveyed up to the longitudinal path roller
54
is conveyed as it is toward the third discharging roller, the page order is reversed.
To avoid reversal in page order, it is necessary to provide a reversing path anew, which leads to an increase in apparatus size. Further, since reversing rollers, etc. have to be provided in the reversing path, an increase in cost and a rather complicated structure are involved.
SUMMARY OF THE INVENTION
The present invention has been made with a view toward solving the above problem. It is an object of the present invention to provide an image forming apparatus capable of discharging sheets without involving any change in page order without having to provide a sheet reversing path anew.
The present invention relates to an image forming apparatus in which an image is formed on sheet by an image forming portion and the sheet is discharged, comprising a main body portion, first discharging means capable of normal and reverse rotation and adapted to discharge the sheet with the image formed thereon to a first discharging portion provided on one side of the main body portion, second discharging means adapted to discharge the sheet with the image formed thereon to a second discharging portion provided on the other side of the main body portion, a first sheet conveyance route for conveying the sheet with the image formed thereon toward the first discharging means, and a second sheet conveyance route for conveying the sheet with the image formed thereon toward the second discharging means, the apparatus being characterized in that sheet discharging direction control means is provided, which, when discharging the sheet to the second discharging portion, causes the sheet with the image formed thereon to be conveyed toward the first sheet conveyance route, and then reverses the first discharging means to convey the sheet toward the second sheet conveyance route.
Also, according to the present invention, an image forming apparatus is characterized in that the sheet discharging direction control means has conveyance route switching means which can be displaced to a first position for conveying the sheet with the image formed thereon toward the first sheet conveyance route and a second position for conveying the sheet conveyed by the first discharging means adapted to be reversed after conveying the sheet toward the first sheet conveyance route, toward the second sheet conveyance route.
Also, according to the present invention, an image forming apparatus is characterized in that the conveyance route switching means is held at the second position by a biasing member and adapted to be displaced to the first position by being pressed by the sheet.
Also, according to the present invention, an image forming apparatus is characterized in that the first discharging portion is a predetermined discharging portion of a plurality of discharging portions provided on one side of the main body p
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