Sheet feeding or delivering – Feeding – Separators
Reexamination Certificate
2001-03-06
2004-01-06
Walsh, Donald P. (Department: 3653)
Sheet feeding or delivering
Feeding
Separators
C271S125000, C271S121000, C271S124000
Reexamination Certificate
active
06672579
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a roller unit in which a pressing force for nipping a sheet member or the like is adjustable, and a transport system of a sheet member in an image processing apparatus using the roller unit.
Moreover, the present invention relates to image reading apparatuses such as an image scanner for reading an original image, image forming apparatuses such as image processing apparatuses or the like in a copying machine or the like, and particularly, to a supply system of a sheet member in an image processing apparatus in which multi-transport of the sheet member can be prevented in a hopper sheet member supply method.
2. Description of Related Art
A roller is frequently used in various equipment fields and, for example, in a rolling line of a steel plate or a transport line of a flat-plate and large-sized material, equipment is usually constituted by arranging a large number of roller pairs on upper, lower and both sides of the line to guide or roll/mold the steel plate or the material. Not only in such large-sized equipment, but also in a field of so-called business machines for image formation or image reading, such as a copy machine, a facsimile apparatus, and an image scanner, various rollers are similarly utilized. For the roller of the business machine, an object to be nipped or guided is a sheet, and thus, a remarkably simplified and lightened structure is general in which, for example, resin is utilized.
The roller is used in various fields in this manner, and, when the steel plate is rolled or the sheet material is transported, and when the sheet is supplied or transported in the business machine, how to set a nipping force of the roller is very important. This nipping force is set in accordance with a distance between shafts of a pair of rollers or an elastic urging force which interacts between the rollers. Moreover, in the rolling equipment, the large-sized material transport equipment, and the like, the nipping force or a rolling force is adjusted by a hydraulic-pressure or pneumatic-pressure cylinder connected to the roller shaft, a link mechanism including a spring or the like. In the equipment including such cylinder and link mechanism, rigidity of a system for setting the nipping force or the rolling force is high, and occupied space therefor also increases.
On the other hand, even in the field associated with the business machine, a constitution for guiding paper and other sheet materials and transporting them due to a friction force by utilizing the pair of rollers, as described above, is employed. Even in such guiding or transporting by the pair of rollers, it is important to set the nipping force between the rollers. For example, in the image scanner, the nipping force before and after an image reading section is intensified to some degree so as to stabilize image reading. In simple guiding or transporting, the nipping force is preferably set to be slightly weak so as to prevent an excessively large tension from being applied to the sheet.
On the other hand, for the image scanner and other image reading or forming business machines, a very large number of components and circuits are incorporated in a limited space of a main body. Therefore, considering from the incorporated space, it is not practical to set the nipping force of the roller pair with the cylinder or link mechanism. This problem has been solved by incorporating the respective roller pair with higher position's accuracy and appropriately determining the distance between the shafts in order to set the nipping force.
However, in a case in which the nipping force is adjusted only with the distance between the shafts of the roller pair, if the incorporating precision of the roller pair is not higher, a desired object cannot be achieved. That is to say, since there is existed a manufacturing error of the roller itself and an incorporating error to a support member for supporting the roller, it is very difficult to set the nipping force with high-accuracy. Moreover, the support member for supporting the roller is securely disposed along a sheet transport path. Thus, if a position of the support member is fixed, change of the roller pair nipping force or another adjustment cannot be performed at all. Therefore, if the nipping force becomes too strong or weak in accordance with a sheet thickness or a paper quality, a function of transporting or guiding the sheet is deteriorated.
As described above, for the guiding roller of the large-sized equipment, the cylinder or the link mechanism can be used to arbitrarily change the roller nipping force. However, in the apparatus associated with the small-sized business machine, the nipping force of the guiding or transporting roller cannot be changed or adjusted, and this causes a problem that the image reading or the image formation is remarkably influenced.
The image reading apparatus such as an image scanner is provided, for example, with a sheet supply apparatus for feeding a sheet set on a hopper into the line. The sheet supply apparatus picks up and feeds out piled sheets one by one from the top, and is, in most cases, provided with a multi-transport preventing system for preventing two or more sheets from being fed by friction of the superposed sheets. The sheet supply apparatus provided with such multi-transport preventing system is described, for example, in JP-A-04-286558.
FIG. 16
is a schematic view showing a typical example of the conventional sheet supply apparatus provided with the multi-transport preventing system, and this apparatus has a constitution substantially similar to the constitution described in the aforementioned publication.
In
FIG. 16
, a hopper
51
for mounting and setting various types of sheets P such as document paper to be read is disposed on a base end of a reading line, and a supply roller
52
for picking up and feeding out an uppermost sheet P is disposed above the hopper
51
. The hopper
51
is urged toward the supply roller
52
by a spring
51
a
, and the sheet P is pressed onto the supply roller
52
so that only the uppermost sheet P is fed out by friction with a peripheral surface of the roller. Moreover, even when a piled thickness of the sheets P changes, a pressing force to the supply roller
52
is held to be substantially constant by the spring
51
a.
On a line of an exit side of the hopper
51
, in order to feed the sheet P to an image reading position, for example, three pairs of transport rollers
53
,
54
,
55
are arranged so that the sheet P fed from the hopper
51
is nipped, drawn out and transported downstream. Moreover, between the hopper
51
and a first pair of transport rollers
53
, a separation roller
56
and a retard roller
57
are disposed as a multi-transport preventing system of the sheet P.
Multi-transport prevention by the separation roller
56
and retard roller
57
is broadly known in fields of an image reading apparatus and copying machine, and the retard roller
57
is constituted by attaching a torque limiter
57
b
around a main shaft
57
a
which is rotated in a direction of an arrow shown in
FIG. 16
by a driving motor (not shown). The main shaft
57
a
of the retard roller
57
is connected to the driving motor (not shown) commonly used for the separation roller
56
, and is urged upward by a spring for setting the nipping force with the separation roller
56
in FIG.
16
. Since such a torque limiter
57
b
is disposed, when one sheet P is fed from the supply roller
52
, the retard roller
57
receives a rotation torque of the separation roller
56
to rotate in a transport direction of the sheet P. Moreover, when two or more sheets P are redundantly transported and nipped, the retard roller
57
keeps rotating in the arrow direction, and the redundantly transported lower sheet P is pushed back toward the hopper
51
.
However, in the conventional retard roller
57
, there is used a torque limiter
57
b
with a fixedly set torque value. That is to say, an operation torque of the torque limite
Araki Takao
Takaki Kosuke
Miller Jonathan R
Walsh Donald P.
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