Electrophotography – Document handling – Original
Reexamination Certificate
1999-07-07
2001-02-06
Chen, Sophia S. (Department: 2852)
Electrophotography
Document handling
Original
C271S902000, C358S498000, C399S043000, C399S371000, C399S406000
Reexamination Certificate
active
06185403
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a sheet conveying device, and an image reading apparatus such as a scanner and an image forming apparatus such as a copying machine, both provided with the sheet conveying device, and more particularly to a sheet conveying device used for conveying a sheet having a relatively large width.
2. Discussion of the Background
Typically, a sheet conveying device which is mounted on a copying machine, a scanner, and the like as an original conveying device to process an original sheet having a relatively large width, such as an D-size sheet in a lateral direction, has a configuration as illustrated, for example, in FIG.
7
.
In such an original conveying device, when a user manually inserts an original P placed on an original table
81
into a nip portion between an entrance drive roller
83
and an entrance driven roller
84
, the leading edge of the original P is detected by an entrance sensor
82
. When the entrance sensor
82
detects the leading edge of the original P, the entrance sensor
82
is turned on and the entrance driven roller
84
is lifted up. After the leading edge of the original P passes through a clearance between the entrance drive roller
83
and the entrance driven roller
84
, the leading edge of the original P is detected by a start sensor
86
. Just after being detected by the start sensor
86
, the leading edge of the original P impinges against a stopping nail
85
. When the start sensor
86
detects the leading edge of the original P, the entrance driven roller
84
is lowered so as to again form the nip portion with the entrance drive roller
83
. The stopping nail
85
also lowers down in synchronism with the lowering operation of the entrance driven roller
84
so as to allow the original P to be conveyed to a nip portion between a pair of registration rollers
87
.
The original P is conveyed by the pair of registration rollers
87
through a reading position between a contact glass
88
and an exposure roller
89
. While being conveyed through the reading position between the contact glass
88
and the exposure roller
89
, the original P is scanned with exposure light and thereby an image of the original P is read by a reading device (not shown). The original P is then conveyed outside of the original conveying device to, for example, a sheet discharging tray (not shown), by a sheet-discharging roller
90
.
An example of an original conveying device having a configuration as described above is described, for example, in Japanese Laid-open Patent Application Tokukaihei No. 6-230638.
FIG. 8
illustrates another type of an original conveying device, in which an entrance driven roller
84
is not lifted-up/lowered-down as in the aforementioned original conveying device. The original P impinges against the nip portion between the entrance driven roller
84
and the entrance drive roller
83
by being guided by a guide MYLAR
91
. The guide MYLAR
91
is arranged such that one end thereof contacts an upper part of the surface of the entrance drive roller
83
. The leading edge of the original P is guided by the MYLAR
91
to a position just before the nip portion between the entrance drive roller
83
and the entrance driven roller
84
. The configuration of the original conveying device is simplified by eliminating a mechanism to lift-up/lower-down the entrance driven roller
84
and the stopping nail
85
.
Typically, the original conveying devices as described above include a plurality of pairs of entrance drive rollers and driven rollers as illustrated in FIG.
9
A.
When the original P is manually inserted into the original conveying devices, the original P must be inserted with the leading edge straight and in parallel with a nip line, which is formed by nip portions between the plurality of pairs of entrance drive rollers
83
and entrance driven rollers
84
, so that the original P is prevented from being skewed and jammed in the nip portions.
However, when the user manually inserts the leading edge of the original P into the nip portions between the entrance drive rollers
83
and the entrance driven rollers
84
, as illustrated in
FIG. 9A
, the leading edge of the original P may not be in parallel with the nip line when the leading edge impinges against the nip portions. This is caused by the original P being caught by a surface of the entrance drive roller
83
, as illustrated in FIG.
9
B.
The entrance drive roller
83
is typically made of material having a relatively high frictional coefficient, such as rubber, and the original P is caught by the surface of the entrance roller
83
due to a frictional resistance between the original P and the surface of the entrance drive roller
83
. Particularly, when the original P has a relatively thin thickness and has a curl, it is difficult to insert the original P so as to be accurately impinged against the nip line of the nip portions. Typically, the leading edge of such a thin original P impinges and does not form a straight line, as illustrated in FIG.
9
A.
A part of the original P that is impinged against the nip portion indicated by point A may be conveyed through the nip portion A antecedently to the other parts of the original P impinging against the nip indicated by points B, as illustrated in FIG.
9
A. As a result, wrinkling, jamming, and skewing of the original P tend to occur.
The original conveying device, which is provided with the stopping nail
85
as illustrated in FIG.
7
and in which the entrance driven rollers
84
are lifted up to allow the leading edge of the original P to pass through the nip portions of the plurality of the entrance drive and driven rollers so as to be impinged against the stopping nail
85
, can cause the leading edge of the original P to be straight by causing the original P to impinge against the stopping nail
85
and thereby the leading edge of the original P can be accurately align at a right angle relative to the conveying direction of the original P. Therefore, wrinkling, jamming, and skewing of the original P is minimized. However, the original conveying device with the above-described configuration with the stopping nail
85
, requires a mechanism to retreat the stopping nail
85
to allow the original P to be conveyed and a mechanism to lift up and lower down the entrance driven roller
84
, which increases the manufacturing cost.
Also, if the original conveying device is configured to include the guide Mylar
91
contacting an upper part of the surface of an entrance drive roller
83
to cause the leading edge of the original P to accurately impinge against the nip portion, as illustrated in
FIG. 8
, the cost of the original conveying device is increased by the provision of the MYLAR
91
. In addition, if the original conveying device provided with the guide MYLAR
91
is configured such that an original is first conveyed in a forward direction and then conveyed in the reverse direction for reading an image on the original P, the original P may be jammed at the MYLAR
91
by being interrupted with the guide MYLAR
91
when the original P is conveyed in the reverse direction. In particular, jamming of the original P may occur when the original P is repeatedly conveyed and reversed for making a plurality of copies or when the original P is discharged in the reverse direction.
SUMMARY OF THE INVENTION
The present invention has been made in view of the above-discussed problems and an object of the invention is to address and resolve these and other problems. A non-exhaustive description of the features and attributes of the invention is presented in this section, with a more complete description provided by the figures and description of the preferred embodiment section of this document.
Another object of the present invention is to provide an inexpensive novel sheet conveying device capable of preventing a sheet from being wrinkled, jammed, or skewed when the sheet is inserted into the conveying device and when it is conveyed in a forward and reverse direction in
Iwasaki Takeshi
Nagasawa Minoru
Toyoshima Yoshio
Chen Sophia S.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Ricoh & Company, Ltd.
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