Sheet feeding or delivering – Feeding – Separators
Reexamination Certificate
2000-07-14
2001-10-30
Bollinger, David H. (Department: 3651)
Sheet feeding or delivering
Feeding
Separators
C271S167000
Reexamination Certificate
active
06308947
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a sheet feeding apparatus for feeding a sheet to an image forming apparatus and the like.
2. Related Background Art
Among conventional sheet feeding apparatuses used in image forming apparatuses such as printers, copying machines, facsimiles and the like, there is a sheet feeding apparatus of inclined surface separation type for effecting sheet separation by using an inclined surface. In the sheet feeding apparatus of inclined surface separation type, an inclined surface is provided in front of stacked sheets, and, when a sheet feeding roller abuts against an uppermost sheet in the sheet stack and feeds the sheets, the fed sheets abut against the inclined surface to be separated one by one.
An example of such a sheet feeding apparatus of inclined surface separation type will be explained with reference to
FIGS. 14
to
16
.
In
FIG. 14
, the sheet feeding apparatus
50
for successively feeding the stacked sheets comprises a sheet feeding tray portion
51
for stacking the sheets to be fed, a sheet feeding portion
52
for separating and feeding the stacked sheets one by one, and a conveying portion
53
for conveying the fed sheet.
The sheet feeding portion
52
includes a sheet feeding roller
54
rotated integrally with a gear (not shown), an idler gear
55
meshed with the gear (not shown) of the sheet feeding roller
54
, an idler gear
56
meshed with the idler gear
55
, a drive gear
57
meshed with the idler gear
56
, a drive shaft
58
attached to be rotated together with the drive gear
57
, and a sheet feeding roller holder
59
rotatably attached to the drive shaft
58
and adapted to rotatably support the sheet feeding roller
54
, idler gears
55
,
56
and drive gear
57
.
The conveying portion
53
includes a lower guide
60
for guiding a lower surface of the sheet fed from the sheet feeding portion
52
, an upper guide
61
for guiding an upper surface of the fed sheet, a conveying roller
62
for conveying the sheet guided by the lower and upper guides
60
,
61
to an image forming portion, a rotatable conveying sub-roller
63
opposed to the conveying roller
62
, a sub-roller holder
64
rotatably supported by the upper guide
61
and adapted to rotatably support the conveying sub-roller
63
, and a conveying spring
65
for biasing the sub-roller holder
64
to urge the conveying sub-roller
63
against the conveying roller
62
.
The sheet feeding tray portion
51
includes a sheet feeding tray
66
for supporting the sheets S in an inclined condition, and a separation inclined surface
67
contiguous to the sheet feeding tray
66
and against which leading ends of the stacked sheets abut and are held and which is adapted to separate the sheets one by one.
In the sheet feeding apparatus
50
having the above-mentioned arrangement, a sheet feeding operation is effected as follows.
The drive shaft
58
receives a driving force from a controllable driving mechanism (not shown), and start and stop of the sheet feeding operation are controlled. When the sheet feeding operation is started, the drive shaft
58
is rotated by the driving mechanism (not shown). Such rotation is transmitted to the sheet feeding roller
54
through the drive gear
57
and idler gears
56
,
55
, thereby rotating the sheet feeding roller
54
.
A sheet feeding roller arm
59
for holding the sheet feeding roller
54
for rotation around the drive shaft
58
is subjected to a force by biasing means (not shown) or by its own weight to be rotated in an anti-clockwise direction, and, by this force, the sheet feeding roller
54
is slightly contacted with an uppermost sheet in the sheet stack rested on the sheet feeding tray
66
of the sheet feeding tray portion
51
.
Accordingly, when the rotation of the sheet feeding roller
54
is started, a feeding force F due to a friction force of the sheet feeding roller
54
acts on the sheet stack S. The sheet stack is subjected to a reaction force F from the separation inclined surface
67
, and, by this reaction force F, the sheet stack is bent along the separation inclined surface
67
, and the sheet stack is advanced in the bent condition while abutting the leading end of the sheet stack against the separation inclined surface
67
. In this case, if the plural sheets are fed out, only the uppermost sheet is separated and fed by the separation inclined surface
67
.
The separated sheet is directed by the upper and lower guides
61
,
60
and enters into a nip defined between the conveying roller
62
and the conveying sub-roller
63
biased toward the conveying roller
62
by the conveying spring
65
and is further conveyed by the conveying roller
62
toward a downstream direction.
In this way, in this sheet feeding apparatus of inclined surface separation type, the sheets can be separated and fed one by one by the separation inclined surface
67
.
In such a sheet feeding apparatus of inclined surface separation type, the sheet stacking surface for stacking the sheets is fixed. Since an arrangement which is generally used and in which an intermediate plate for stacking sheets is rockably provided and is biased by a spring is not required, and, since additional separation claws or separation pads are not required because only the inclined surface may be provided as separation means, the construction becomes simpler and cheaper. Further, since thick sheets which could not separated by the separation claws can be separated, the kind of sheets to be separated is increased.
Incidentally, in the above-mentioned conventional technique, while an example that the inclined surface separation system is applied to the sheet feeding apparatus having the inclined sheet feeding tray was explained, the inclined surface separation system may be applied to a sheet feeding apparatus in which sheets are supported and fed out in a horizontal condition. Further, the separation inclined surface may be provided on a so-called sheet feeding cassette for stacking sheets detachably attachable to a main body of the apparatus.
An example that the separation inclined surface is provided on the sheet feeding cassette will be explained with reference to FIG.
17
.
A sheet feeding cassette
71
detachably attachable to a main body
70
of the apparatus is mounted to the main body
70
of the apparatus from a direction shown by the arrow. The sheet feeding cassette
71
includes a resting surface
72
on which sheets S are stacked, a separation inclined surface
73
for separating the sheets, and a trailing end regulating plate
74
for regulating trailing ends of the sheets S stacked on the resting surface
72
. The separation inclined surface
73
is located at a front part of the sheet feeding cassette
71
in a mounting direction.
The main body
70
of the apparatus includes a sheet feeding roller
75
for feeding out the sheets S contained in the sheet feeding cassette
71
, and the sheet feeding roller
75
is supported by a sheet feeding roller holder
77
rotatable around a rotary fulcrum
76
.
When the sheet feeding cassette
71
containing the sheets is mounted to the main body
70
of the apparatus and the sheet feeding roller
75
is rotated while contacting with the upper surface of the sheet stack, the sheets are fed, and the fed sheets abut against the separation inclined surface
73
and are separated one by one.
However, the above-mentioned conventional sheet feeding apparatus
50
arose the following problems.
When the sheet bundle (stack) is inserted onto the sheet feeding tray portion
51
forcibly for sheet replenishment, since the separation inclined surface
67
is inclined with respect to the sheet inserting direction, if the sheet stack abuts against the separation inclined surface
67
strongly, the leading end of the sheet stack will be deformed as shown in FIG.
15
. Such deformation may cause double-feeding or multi-feeding when the sheets are fed out by the sheet feeding roller
54
. Further, if a large number of sheets are inserted onto the sheet feeding
Inoue Ryukichi
Kojima Ryuichi
Matsuo Yoshihiro
Yamazaki Yoshiyuki
Bollinger David H.
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
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