Electrophotography – Document handling – Copy
Reexamination Certificate
1999-10-28
2001-03-27
Grainger, Quana M. (Department: 2852)
Electrophotography
Document handling
Copy
Reexamination Certificate
active
06208830
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a printing apparatus for printing images using, a photosensitive unit such as a photosensitive drum. In particular, the present invention relates to a printer incorporating a paper-cutting mechanism to cut continuous recording paper into separate cut sheets for printing desired images on these cut sheets.
2. Description of the Related Art
A conventional printer of the above type is disclosed in JP-A-7(1995)-304220 for example. As shown in
FIG. 7
of the accompanying drawings of the present application, the conventional printer has an image forming section provided with a photosensitive belt
90
, a transfer unit
91
and a fixation unit
92
. The printer also includes a paper holder
93
for accommodating a paper roll R. Continuous recording paper
94
is paid out from the paper roll R to be brought into contact with the photosensitive belt
90
by a plurality of feed rollers
95
.
In the conventional printer, use is made of a sensor
96
and a cutter
97
, each of which is arranged at a suitable location along the feeding path of the continuous paper
94
. The sensor
96
is provided for detecting the passage of the continuous paper
94
, while the cutter
97
is provided for cutting the continuous paper
94
. More specifically, the sensor
96
is arranged to detect the passage of the leading portion of the continuous paper
94
. Upon such detection, the continuous paper
94
is advanced a predetermined distance toward the photosensitive belt
90
. Then, after the continuous paper
94
has been thus moved, the cutter
97
is operated to cut the continuous paper
94
to provide a cut sheet of a predetermined size.
The advantages of the conventional printer are as follows. Firstly, the recording paper
94
is a single elongated sheet when it is drawn out from the paper holder
93
. Thus, the recording paper
94
will not suffer the problem of “double feed” which is liable to occur when initially separate cut sheets are used in place of the continuous paper
94
.
Secondly, the continuous paper
94
is not allowed to maintain its continuous form but is cut into separate sheets by the cutter
97
arranged upstream from the photosensitive belt
90
. With such an arrangement, the mechanisms of components arranged behind (i.e., downstream from) the photosensitive belt
90
are advantageously simplified, as in a specialized printer which is designed to deal with cut sheets only. This advantage can be better understood by considering the following case.
If the continuous paper
94
is not to be cut into separate cut sheets at all, additional devices, which would otherwise be unnecessary, may be required. The additional devices may include devices to detach the photosensitive belt
90
and the fixation unit
92
from the continuous paper
94
when the printing operation should be halted temporarily. Such detachment is needed for protecting the belt
90
from possible mechanical damage inflicted by the continuous paper
94
, and for protecting the paper
94
from possible thermal damage inflicted by the fixation unit
92
. The additional devices may also include a folding device for the continuous paper
94
. The folding device may be disposed at the end of the feeding path for alternately folding the continuous paper
94
, so that the discharged paper
94
is neatly accommodated in a stacker.
Though the conventional printer possesses the above advantages, it has been found disadvantageous in the following points.
In the conventional printer, the continuous paper
94
is cut into a separate sheet before the leading portion of the continuous paper
94
comes into contact with the photosensitive belt
90
. Thus, the cut sheet separated from the continuous paper
94
needs to be transferred a certain distance until it comes into contact with the photosensitive belt
90
. In this manner, the cut sheet tends to be improperly oriented (skewed for example) during the transfer to the photosensitive belt
90
. When such improper transfer occurs, the cut sheet may fail to come into square contact with the photosensitive belt
90
. Consequently, the printing operation may be started at an unintended portion of the cut sheet, and the resulting image printed on the cut sheet may unfavorably be slanted.
SUMMARY OF THE INVENTION
The present invention has been proposed under the above circumstances, and its objective is to eliminate, or at least reduce, the problems described above.
For attaining the above objective, the present invention takes the following technical measures.
According to the present invention, there is provided a printer with a photosensitive member comprising:
an image forming section for forming an toner image on a surface of the photosensitive member;
continuous paper to which the toner image is transferred from the photosensitive member;
a paper feeding unit for feeding the continuous paper along a feeding path to the surface of the photosensitive member; and
a cutting unit for cutting the continuous paper to provide a cut sheet, the cutting unit being arranged upstream from the photosensitive member;
wherein the cutting unit is arranged to cut the continuous paper after a leading portion of the continuous paper reaches the surface of the photosensitive member.
With such an arrangement, when the continuous paper is cut by the cutting unit, the leading portion of the continuous paper has already arrived at the surface of the photosensitive member. Thus, as opposed to the conventional printer, the cut sheet separated from the continuous paper does not need to be transferred to the photosensitive member. In this manner, the positioning of the cut sheet relative to the photosensitive member can be accurately performed. As a result, it is possible to reduce, or even eliminate, the positional deviation of the image to be printed on the cut sheet.
According to a preferred embodiment, the printer may further comprise a detector for detecting the leading portion of the continuous paper, wherein the detector is arranged upstream from the photosensitive member.
With such a printer provided, the paper feeding unit may be arranged to advance the continuous paper by a predetermined amount after the leading portion of the continuous paper is detected by the detector.
Further, the cutting unit may be arranged to cut the continuous paper after the continuous paper is advanced by said predetermined amount.
Preferably, the paper feeding unit of the printer may comprise at least one tractor including a rotating member provided with a plurality of protrusions which are inserted into feed holes formed in the continuous paper.
With such an arrangement, the problem of possible slip or positional deviation of the continuous paper with respect to the paper feeding unit can be overcome.
Preferably, the feed holes may be disposed along a longitudinal edge of the continuous paper at regular intervals.
Preferably, the rotating member may be an endless belt or a roller.
Preferably, the continuous paper may be provided with cut lines arranged at regular intervals longitudinally of the continuous paper, and each of the cut lines may include at least one cut.
The cutting unit may be arranged to cut the continuous paper at the cut lines.
Preferably, the cutting unit may be movable along the feeding path of the continuous paper. With such an arrangement, by adjusting the fixing position of the cutting unit along the feeding path, the length of the cut sheet separated from the continuous paper can be varied.
Advantageously, the paper feeding unit may include an additional tractor arranged downstream from the above-mentioned one tractor.
Further, the above-mentioned one tractor may preferably be arranged to exert a resisting force on the continuous paper advancing along the feeding path, so that the continuous paper is cut at a cut line.
With such an arrangement, the paper feeding unit can achieve two functions, that is, the paper feeding function and the paper cutting function. In this situation, there is no need to render the p
Armstrong, Westerman Hattori, McLeland & Naughton
Fujitsu Limited
Grainger Quana M.
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