Electrophotography – Document handling – Copy
Reexamination Certificate
2003-09-03
2004-11-30
Colilla, Daniel J. (Department: 2854)
Electrophotography
Document handling
Copy
C400S624000, C400S706100, C400S708000, C271S144000, C271S171000
Reexamination Certificate
active
06826383
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a sheet size detection apparatus for detecting the size of a sheet and an image forming apparatus, such as a copying machine, a facsimile machine, a printer or a multifunction machine serving as a combination of those machines, for forming an image on a sheet based on sheet size information obtained by the sheet size detection apparatus.
2. Description of the Related Art
Generally, an image forming apparatus forms an image on a sheet in accordance with the sheet size, and therefore the apparatus main body is designed to recognize the size of a sheet(s) that is set in a sheet feed tray by a user. Some high grade image forming apparatus with which restriction on cost is light are provided with a mechanism that is interlocked with the position of a regulation member for regulating the width direction or the length direction of the sheets on a sheet feed tray to detect the sheet size automatically. However, such a mechanism requires a complex link mechanism or the like, which sometimes causes an increase in the cost. On this account, some common image forming apparatus is provided with a sheet size selection member with which the sheet size setting is selected-by a user manually.
Conventional common sheet size detection apparatus are shown in
FIGS. 12 and 13
.
FIG. 12
is a perspective view showing a sheet feed tray
130
provided with a conventional sheet size detection apparatus
102
using a slide type sheet size selection member
151
.
The sheet size selection member
151
is provided on a front edge portion
130
e
of the sheet feed tray and adapted to be slidable in the direction along the front edge portion
130
e
shown by the arrow A (i.e. in the horizontal direction). On the backside wall of the sheet size selection member
151
, there is provided a predetermined pattern including projections and depressions (not shown).
The sheet size detection apparatus
102
is constructed in such a way that upon setting sheets on the sheet feed tray
130
, the user would cause the sheet size selection member
151
to slide in the directions indicated by the double-headed arrow A to a position corresponding to the size of the set sheets to set the size. This is done by adjusting a size pointer
152
of the sheet size selection member
151
with an appropriate position on a sheet size scale provided on the front edge portion
130
e
of the sheet feed tray
130
.
When the user pushes the sheet feed tray
130
in the sheet feeding cassette attaching (or loading) direction indicated by the arrow X to bring it into the main body
101
of the image forming apparatus
100
, the sheet size detection apparatus
102
reads the pattern on the sheet size selection member
151
by means of a size detection sensor
150
provided on the apparatus main body
101
to detect the sheet size so that the apparatus main body would recognize the sheet size.
FIG. 13
is a perspective view showing a sheet feed tray
230
provided with a conventional sheet size detection apparatus
202
using a rotary type sheet size selection member
261
.
The sheet size selection member
261
is provided on a front edge portion
230
e
of the sheet feed tray
230
and adapted to be rotatable. On the cylinder side wall
261
b
of the sheet size selection member
261
, there is provided a predetermined pattern including projections and depressions in a manner similar to the above-described slide type sheet size selection member
161
.
The sheet size detection apparatus
202
is constructed in such a way that upon setting sheets on the sheet feed tray
230
, the user would rotate the sheet size selection member
261
in the direction indicated by the arrow B to cause a sheet size name selected from a sheet size scale provided on the top surface of the sheet size selection member
261
to be aligned with the position of a size pointer
264
. When the user pushes the sheet feed tray
230
in the sheet feeding cassette attaching direction indicated by the arrow X to bring it into the main body
201
of the image forming apparatus
200
, the sheet size detection apparatus
202
reads the pattern on the sheet size selection member
261
by a size detection sensor
260
provided on the apparatus main body
201
to detect the sheet size so that the apparatus main body would recognize the sheet size.
The conventional sheet size detection apparatus
102
and
202
provided with the sheet size selection member
151
and
261
having the above-described structures have advantages that setting of the sheet size can be performed with a simple structure. However, they suffer from the following problems.
Set positions of the sheet size selection member
151
and
261
are easy to be displaced inadvertently. From the standpoint of improving operability, it is preferable to provide the sheet size selection member
151
or
261
on the front edge portion
130
e
or
230
e
of the sheet feed tray
130
or
230
. However, with that layout, when the user sets sheets on the sheet feed tray
130
or
230
, it is likely that the user's hands or the sheets touch the sheet size selection member
151
or
261
. Consequently, the set position of the sheet size selection member
151
or
261
is sometimes changed upon setting of the sheets, so that the size detection sensor detects a different sheet size.
Furthermore, the image forming apparatus provided with such a sheet size detection apparatus sometimes recognizes the sheet size erroneously. This may cause malfunction of the apparatus or a jam.
The sheet size selection members
151
and
261
are sometimes set to a position displaced from the position to be set to only a small extent. In that case, it is difficult for the user to find the displacement. In aid of user's operation for positioning the size selection member, the sheet size selection member is generally designed to generate click feeling at predetermined set positions as the sheet size selection member is moved. However, it is not so easy for the user to set the sheet size selection member
151
or
261
to a predetermined position based only on the click feeling.
As per the above, even if the user believes that he or she has set the sheet size correctly, the sheet size may be erroneously set in reality. Furthermore, in the case that the position of the sheet size selection member
151
or
261
is displaced only to a small extent, it is difficult for the user to recognize it visually. Consequently, when the image forming apparatus is in trouble, it will require significant labor and take significant time to find the cause of the trouble.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a sheet size detection apparatus that can prevent inadvertent operation mistakes upon sheet loading, enhance visibility and prevent it from being neglected to be operated.
Another object of the present invention is to provide an image forming apparatus equipped with the above-mentioned sheet size detection apparatus with which the possibility of an operation mistake or a sheet jam is low.
A sheet size detection apparatus according to the present invention comprises:
sheet stacking means on which sheets are stacked and which can be loaded into and unloaded from a loading portion;
a sheet size selection member provided on the sheet stacking means, a position of the sheet size selection member being changeable in accordance with a size of stacked sheets;
sheet size detection means provided on the loading portion to detect the sheet size based on a relative positional relationship with the sheet size selection member;
locking means that can lock the sheet size selection member; and
unlock means for releasing a locking operation of the locking means.
Furthermore, a sheet size detection apparatus according to the present invention comprises:
a sheet feed tray detachably provided on an apparatus main body and having an inner plate on which sheets are to be stacked;
a sheet size selector slidably provided on the sheet feed tray and to be set at
Canon Kabushiki Kaisha
Colilla Daniel J.
Fitzpatrick ,Cella, Harper & Scinto
Ghatt Dave A.
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