Sheet feeding or delivering – Delivering – With transfer means between conveyor and receiver
Reexamination Certificate
1999-12-15
2002-06-04
Ellis, Christopher P. (Department: 3651)
Sheet feeding or delivering
Delivering
With transfer means between conveyor and receiver
C271S291000, C271S303000
Reexamination Certificate
active
06398212
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a sheet surface reversing device for reversing a front surface and a back surface of a sheet by feeding the sheet reversely on the way of conveyance of the sheet along a conveying direction, and an image forming apparatus having such a sheet surface reversing device, such as a copying machine, a facsimile, a printer or combination thereof.
2. Related Background Art
Conventionally, for example, in a sheet surface reversing device incorporated into a copying machine, a rotary member generally called a flapper has been rotated by a solenoid to switch a sheet conveying direction. And, a technique in which an elastic member is provided on a distal end of the flapper is also well-known.
Incidentally, the sheet may include a normal paper (plain paper), a resin sheet having a small thickness (as a substitute article for the normal paper), a post card, a paper board, an envelope, a plastic thin film or the like.
FIG. 8
shows an example of a sheet surface reversing device, in which an elastic member made of Mylar (trade name), for example, is used for a guide piece (conveying path switching member)
101
of a rotary member
100
. In
FIG. 8
, a sheet enters from a direction B
1
, and the sheet can be switched toward a direction C
1
by rotating forwardly and reversely surface reverse rollers
104
and by abutting the guide piece
101
serving as a valve against a wall of the convey path. However, in the example of
FIG. 8
, as shown in
FIG. 9
, during the reversing operation for the sheet, in dependence upon a condition of the sheet (curl, rigidity and/or material), a leading end of the sheet may be caught by a distal end of the guide piece
101
, with the result that the leading end of the sheet may be folded or the sheet may be jammed at worst.
Another conventional example is disclosed in Japanese Utility Model Publication No. 6-38838, for example.
FIG. 10
shows a characteristic portion of such another example, in which a distal end of an elastic guide piece
101
is protruded outwardly through a hole
105
formed in a guide plate
103
. With this arrangement, during the reverse feed of the sheet, the leading end of the sheet can be prevented from being caught by the distal end of the guide piece
101
.
Further, a further conventional example is disclosed in Japanese Patent Application Laid-Open No. 59-118482.
FIG. 11
shows a characteristic portion of such an example. After a sheet passed between guide portions
112
and
113
is conveyed in a direction indicated by the arrow a, the sheet is conveyed by a surface reverse roller (not shown) in a direction indicated by the arrow b. Above the guide portion
112
, there are disposed a guide portion
110
and an elastic guide piece
111
attached to the guide portion
110
. The guide piece
111
has a pectination (comb) shape and comprises protruded portions
111
a
and recessed portions
111
b
, and distal ends of the protruded portions
111
a
block or close a conveying path defined between the guide portions
112
and
113
and are located at a sunken position lower than a plane of the guide portion
113
extending along the arrow b. With this arrangement, when the sheet is conveyed in the direction indicated by the arrow a, the sheet can easily advance while pushing out the protruded portions
111
a
; whereas, when the sheet is conveyed in the direction indicated by the arrow b, the sheet is offered to be prevented from entering into the conveying path between the guide portions
112
and
113
and the leading end of the sheet is offered to be prevented from being caught.
However, the above-mentioned conventional examples have the following disadvantages.
First of all, in the example shown in
FIG. 10
, if the elastic guide piece
101
has a uniform shape (for example, rectangular shape) over the entire length in the longitudinal direction, the corresponding hole
105
also extends continuously along the length of the guide piece
101
. As a result, depending upon the curled state of the sheet, the leading end of the sheet being conveyed may be caught by the hole
105
or the sheet may escape out of the guide portion. In order to avoid this, an arrangement as shown in
FIG. 12
can be considered.
A guide piece
101
has a pectination (comb) shape and comprises protruded portions
101
b
and recessed portions
101
a
, and a guide plate
103
opposed to the protruded portions
101
b
is provided with holes
105
which is associated with the protruded portions
101
b
and into which free ends of the corresponding protruded portions
101
b
are inserted. By providing such holes
105
divided along the longitudinal direction, even when a sheet S is advanced from a direction indicated by the arrow B
1
, the sheet S can be prevented from escaping outside through the holes. Further, in order to switch the conveying path, side edges of a sheet S which is apt to be caught (for example, in
FIG. 12
, side edges of a sheet having A
4
size or B
5
size) are passed positions off the holes
105
(over the recessed portions
101
a
).
However, even with the arrangement as shown in
FIG. 12
, due to skew-feed of the sheet for any reason or in dependence upon the curled state of the sheet, the sheet may be caught by the recessed portion
101
a
or the hole
105
, and, thus, adequate reliability is not ensured.
Further, in the example shown in
FIG. 11
, since the recessed portions
111
b
of the guide piece
111
are spaced apart from a stepped portion of the guide
113
more or less, the same problem that the leading end of the curled sheet is apt to be caught arises. Further, since the pectination shape is used, the rigidity is reduced to easily cause deformation, with the result that the protruded portions
111
a
may be floating from the stepped portion to catch the sheet.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a sheet surface reversing device in which a sheet is prevented from being jammed due to interference between a leading end of the sheet conveyed reversely and a distal end of a conveying path changing member, and stable sheet conveyance can be achieved, and an image forming apparatus having such a sheet surface reversing device.
To achieve the above object, according to the present invention, there is provided a sheet surface reversing device comprising a sheet conveying path through which a sheet is conveyed, reverse feeding means for reversely feeding the sheet conveyed through the sheet conveying path, a sheet surface reverse conveying path for directing the sheet reversely fed from the reverse feeding means, and a conveying path changing member rotatably disposed at a branched portion between the sheet conveying path and the sheet surface reverse conveying path, wherein, in a state that a distal end of the conveying path changing member abuts against an inner wall of the sheet conveying path, the distal end guides the sheet to be reversely fed into the sheet surface reverse conveying path, and wherein interference avoiding means for avoiding interference between the sheet reversely fed and the distal end of the conveying path changing member are provided on the inner wall of the sheet conveying path.
With this arrangement, when the sheet is reversely fed by the reverse feeding means, the rotating distal end of the conveying path changing member abuts against the inner wall of the sheet. conveying path, and the interference avoiding means conceals the rotating distal end not to be seen from the reverse feeding means. Thus, the interference avoiding means can cause a leading end of the sheet reversely fed (trailing end of the sheet conveyed through the sheet conveying path) to pass over the rotating distal end of the conveying path changing member thereby to avoid the interference between the leading end of the sheet and the rotating distal end of the conveying path changing member, thereby guiding the sheet reversely fed into the sheet surface reverse conveying path smoothly. In this way, the sheet can be prevent
Deuble Mark A.
Ellis Christopher P.
LandOfFree
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