U.S. patent application number 10/815838 was filed with the patent office on 2005-10-06 for paper supply device and image forming apparatus.
This patent application is currently assigned to KABUSHIKI KAISHA TOSHIBA. Invention is credited to Kitazawa, Osamu.
Application Number | 20050218581 10/815838 |
Document ID | / |
Family ID | 35053406 |
Filed Date | 2005-10-06 |
United States Patent
Application |
20050218581 |
Kind Code |
A1 |
Kitazawa, Osamu |
October 6, 2005 |
Paper supply device and image forming apparatus
Abstract
This invention is to generate a press fitting force between the
paper supply roller and the separation roller by attaching a weight
to the paper supply shaft of the paper supply roller to feed sheets
of paper and applying a load to the paper supply roller. The press
fitting force of the paper supply roller generated by a load of the
weight remains unchanged irrespective of secular change or wear of
the paper supply roller or the separation roller and is kept in the
same level as that at the initial stage, and the separation and
conveying of sheets of paper by the paper supply roller and the
separation roller can be carried out certainly for an extended
period.
Inventors: |
Kitazawa, Osamu;
(Kanagawa-ken, JP) |
Correspondence
Address: |
FOLEY AND LARDNER
SUITE 500
3000 K STREET NW
WASHINGTON
DC
20007
US
|
Assignee: |
KABUSHIKI KAISHA TOSHIBA
TOSHIBA TEC KABUSHIKI KAISHA
|
Family ID: |
35053406 |
Appl. No.: |
10/815838 |
Filed: |
April 2, 2004 |
Current U.S.
Class: |
271/109 |
Current CPC
Class: |
B65H 3/06 20130101; B65H
27/00 20130101 |
Class at
Publication: |
271/109 |
International
Class: |
B65H 003/06 |
Claims
What is claimed is:
1. A paper supply device comprising: a paper supply roller that
rotates in the sheets of paper supplying direction; a separation
roller that holds the sheets of paper jointly with the paper supply
roller and always maintains a driving force in the direction
reverse to the paper supplying direction by the paper supply
roller; and a weight to press fit the paper supply roller to the
separation roller by applying a required load to the paper supply
roller.
2. The paper supply device according to claim 1, wherein the weight
is mounted on the same shaft of the paper supply roller
coaxially.
3. The paper supply device according to claim 1, wherein the paper
supply roller is connected to a driving mechanism for rotating in
the sheet paper supplying direction at one end of the shaft and
press fits to the separation roller using one end of the shaft as a
revolving point.
4. The paper supply device according to claim 1, wherein the
separation roller retains the driving force in the direction
reverse to the paper supplying direction via a torque limiter.
5. A paper supply device comprising: a paper supply roller that
rotates in the sheet paper supplying direction; a separation roller
that holds sheets of paper jointly with the paper supply roller and
always retains a driving force in the direction reverse to the
paper supplying direction by the paper supply roller; a weight that
applies a required load to the paper supply roller and press fits
the paper supply roller to the separation roller by the applied
load; and an elastic member that press fits the paper supply roller
to the separation roller by applying the compression force to
either the paper supply roller or the separation roller.
6. The paper supply device according to claim 5, wherein the
elastic member presses the paper supply roller to the separation
roller side, and the paper supply roller is press fit to the
separation roller by a load applied by the weight and the pressure
of the elastic member.
7. The paper supply device according to claim 6, wherein the weight
is attached to the same shaft of the paper supply device
coaxially.
8. The paper supply device according to claim 6, wherein the paper
supply roller is connected to a driving mechanism for rotating in
the sheet paper supplying direction at one end of the shaft and is
press fit to the separation roller using one end of the shaft as a
revolving support point.
9. The paper supply device according to claim 6, wherein the
separation roller retains a driving force in the direction reverse
to the paper supplying direction via a torque limiter.
10. The paper supply device according to claim 6, wherein 1/2 of
the press fitting force to fit the paper supply roller to the
separation roller is produced with the own weight of the paper
supply roller and the weight, and the remaining 1/2 is produced
with compression force of the elastic member.
11. An image forming apparatus comprising: an image carrier; an
image forming unit to form a toner image on the image carrier; a
transfer unit to transfer the toner image on sheets of paper; a
paper supply roller to revolve to feed paper in the direction of
the transfer unit; a separation roller to always retain a driving
force in the direction reverse to the paper supplying direction by
the paper supply roller; and a weight to apply a required load to
the paper supply roller and press fit the paper supply roller to
the separation roller by the applied load.
12. The image forming apparatus according to claim 11, wherein the
weight is attached to the same shaft of the paper supply roller
coaxially.
13. The image forming apparatus according to claim 11, wherein the
paper supply roller is connected to a driving mechanism for
revolving at one end of the shaft in the paper supplying direction
and press fit to the separation roller using one end of the shaft
as a revolving support point.
14. The image forming apparatus according to claim 11, wherein the
separation roller retains a driving force in the direction reverse
to the paper supplying direction via a torque limiter.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates to a paper supply device to convey
sheets of paper in the paper supplying direction by separating one
by one certainly and an image forming apparatus.
[0003] 2. Description of the Related Art
[0004] In image forming apparatus such as printers, copying
machines or facsimiles, a paper separation mechanism is
incorporated to supply sheets of paper taken out of paper supply
cassettes or paper supply tray by separating one by one in a
direction of image forming apparatus. As one of sheet separation
mechanisms, there is an image forming apparatus that has a paper
supply roller to rotates sheets of paper in the paper supply
direction and a separation roller to rotates in the reverse
direction through a torque limiter to separate sheets of paper one
by one pass between a paper supply roller and a separation roller.
A device to compress a separation roller to a stationary paper
supply roller with a spring or other press fitting means is
disclosed in Japanese Patent Publication No. 11-199075.
[0005] However, in an apparatus which press fits a paper supply
roller and a separation roller by a press fitting means such as an
above-mentioned spring, press fitting forces of the paper supply
roller and the separation roller change according to variance or
change of compression force of a press fitting means for fatigue or
decrease in the outer diameters of the rollers and change in
mounting conditions of a press fitting means resulting from the
wear of the outer circumference of the paper supply roller or the
separation roller. Therefore, the press fitting force between the
paper supply roller and the separation roller goes out from the
sheet paper separatable range and paper clogging for impossibility
of paper supplying or overlapped sheet feeding for impossibility of
separation can be generated. Further, when it is tried to prevent
the change in mutual pressure fitting force of the paper supply
roller and the separation roller in a construction using such press
fitting means as the above-mentioned spring, etc., various
restrictions may be generated in specifications of press fitting
means and rollers and cost increase may result.
[0006] Therefore, an image forming apparatus using a paper supply
device capable of surely separating and conveying sheets of paper
for an extended period by reducing change in mutual pressure
fitting force of a paper supply roller and a separation roller for
variance in press fitting force or secular change at a low price is
demanded.
SUMMARY OF THE INVENTION
[0007] An object of this invention is to separate sheets of paper
and convey surely for an extended period by holding a press fitting
force between a paper supply roller and a separation roller within
a sheets of paper separable range without impeding the achievement
of cost reduction.
[0008] According to the embodiments of this invention, a paper
supply device has a paper supply roller to rotate in the paper
supply direction, a separation roller to hold a paper jointly with
the paper supply roller and constantly maintain a driving force to
drive paper in the reverse direction of the paper supply roller,
and a weight to press fit the paper supply roller to the separation
roller by applying a required load to the paper supply roller.
[0009] Further, according to the embodiments of this invention, a
paper supply device has a paper supply roller to rotate in the
paper supply direction, a separation roller to hold a paper jointly
with the paper supply roller and always maintain a driving force in
the direction reverse to the paper supplying direction by the paper
supply roller, a weight to apply a required load to the paper
supply roller and press fit the paper supply roller to the
separation roller, and an elastic member to press fit between the
paper supply roller and the separation roller by applying a
compression force to either the paper supply roller or the
separation roller separation roller.
[0010] Further, according to the embodiments of this invention, an
image forming apparatus has an image carrier, an image forming unit
to form a toner image on the image carrier, a transfer unit to
transfer the toner image on a sheet paper, a paper supply roller to
rotate to feed sheet paper in the direction of the transfer unit, a
separation roller to hold the sheet paper jointly with the paper
supply roller and always retain a driving force in the direction
reverse to the paper supply direction by the paper supply roller,
and a weight to apply a required load to the paper supply roller
and press fit the paper supply roller to the separation roller by
the load.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a schematic construction diagram showing an image
forming apparatus in a first embodiment of this invention;
[0012] FIG. 2 is a schematic perspective view showing a
separation/conveying device in the first embodiment of this
invention;
[0013] FIG. 3 is a side view showing the separation/conveying
device in the first embodiment of this invention;
[0014] FIG. 4 is a schematic explanatory diagram showing the press
fitting of a paper supply roller and a separation roller in the
first embodiment of this invention;
[0015] FIG. 5 is a graph showing press fit force setting conditions
of the paper supply roller in the first embodiment of this
invention;
[0016] FIG. 6 is a schematic perspective view showing a
separation/conveying device in a second embodiment of this
invention; and
[0017] FIG. 7 is a graph showing a range of variance of the press
fit force of a paper supply roller at the initial stage in the
second embodiment of this invention.
DETAILED DESCRIPTION OF THE INVENTION
[0018] A first embodiment of this invention will be explained below
in detail referring to the attached drawings. FIG. 1 is a
construction diagram showing the entire construction of a
monochromatic image forming apparatus 10 to which supplies sheets
of paper using a paper supply device in the first embodiment of
this invention. Image forming apparatus 10 is equipped with a
cassette mechanism 3 comprising paper supply cassettes 3a, 3b, 3c
and 3d to feed sheets of paper P that are recording media in the
direction of image forming unit 2. Further, image forming apparatus
10 is equipped with a manual paper supplying mechanism to take out
sheets of paper P with a manual pick-up roller 4b from a paper
supply tray 4a and separate and convey sheets of paper P with a
manual separation roller 4c, and a reverse conveying path 5 to
reverse and convey sheets of paper P when it is desired to form
images on the both side of sheets of paper. On the top of image
forming apparatus 10, a scanner device 6 is provided to read
document images.
[0019] Scanner 6 has a document glass 61 on which documents are
placed, a platen 62 to cover document glass 61, an optical system
unit 63 to apply light to documents and focus reflecting light from
documents, and a CCD scanner unit 64 to read light from optical
system unit 63.
[0020] Developing image forming unit 2 has a charger 12 to
uniformly charge a photosensitive drum 11 sequentially according to
the rotating direction of an arrow q of photosensitive drum 11, an
exposing unit 13a of a laser optical device to form a latent image
on charged photosensitive drum 11 based on image data from scanner
6, a developing unit 14, a transfer charger 16 that is a transfer
unit, a separation charger 17, a cleaner unit 18 and a charge
eliminating LED 19 around photosensitive drum 11 that is an image
carrier.
[0021] At the downstream side in the conveying direction of sheets
of paper P of developing image forming unit 2, a fixing device 22
is provided to convey sheets of paper P by holding with a heat
roller 20 having a built-in heater lamp and fix a toner image by
heating and pressing it. At the downstream of fixing device 22,
discharge rollers 24 are provided to discharge sheets of paper P on
a discharge tray 23 after fixed.
[0022] A conveying path 7 having pick-up rollers 30a, 30b, 30c, 30d
to take out sheets of paper P, a separation/ conveying device 31a
that is a paper supplying device having a paper supply roller pair
37, and first through third conveying rollers 32a, 32b, 32c and
aligning rollers 33 are provided between paper supply cassettes 3a,
3b, 3c, 3d and developed image forming unit 2.
[0023] Next, separation/conveying devices 31a to 31d will be
described in detail. Further, separation/conveying devices 31a to
31d are in the same construction and therefore, taking one them as
an example, they will be explained. For example,
separation/conveying device 31a has a paper supply roller 37, a
sheets of paper P separation roller 38 opposing to paper supply
roller 37, and metal weight 40 attached to a paper supply shaft 37a
as shown in FIG. 2 and FIG. 3.
[0024] Separation roller 38 is made of synthetic rubber, etc.
having a high coefficient of friction and attached to separation
shaft 38 via a torque limiter 42. Separation shaft 38a is supported
at both ends by separation roller bearing unit 44 fixed to a rib 43
provided in conveying path 7. Separation roller 38 is blocked to
rotate in the direction, that is the paper supplying direction, of
transfer charger 16 until a torque applied to separation roller 38
by opposite paper supply roller 37 exceeds a reversing torque. When
the torque applied to separation roller 38 by paper supply roller
37 exceeds the reversing torque, separation roller 38 is switched
to follow the drive of paper supply roller 37 or sheets of paper P
conveyed and driven in the arrow direction r, that is the paper
supply direction.
[0025] Paper supply roller 37 is made of synthetic rubber, etc.
having a high coefficient of friction and is driven and rotated by
a driving motor 47 via paper supply shaft 37a in the arrow
direction s; that is, the paper supply direction, and conveys
sheets of paper P in the direction of photosensitive drum 11. The
drive input side of paper supply shaft 37a that is linked to
driving motor 47 via a joint 50 is supported by a stationary
supporting point side bearing unit 48. Paper supply shaft 37a is
able to oscillate in the arrow direction t centering around
supporting point side bearing unit 48.
[0026] As being capable of oscillating in the arrow direction t,
paper supply shaft 37a is directed to slide to a slit 51a of a
pressurizing side bearing unit 51 near paper supply roller 37.
Further, as paper supply shaft 37a is oscillated in the arrow
direction t, a paper supply gear 46 has a certain play with driving
motor 47.
[0027] Weight 40 is attached to the oscillation side of paper
supply shaft 37a and applies a load to paper supply roller 37.
Paper supply roller 37 is press contacted to separation roller 38
by it's own weight and a load of weight 40 toward a center 38b of
separation roller 38 as shown by an arrow u in FIG. 4.
[0028] Setting conditions of the press fitting force of paper
supply roller 37 to separation roller 38 and a reversing torque of
torque limiter 42 in the feeding of sheets of paper P by
separation/conveying device 31a in this embodiment are restricted
as shown in FIG. 5. A hatched trapezoidal area (.gamma.) of press
fitting force 350 to 450 (gf) enclosed by a non-feed generating
area (.alpha.) and overlapped sheets feed generating area (.beta.)
is an area for the good separation/conveying and an area for
setting a press fitting force of paper supply roller 37 and a
reversing torque of torque limiter 42. Further, this trapezoidal
area (.gamma.) is virtually controlled by type of using sheets of
paper, and coefficients of friction of paper supply roller 37 and
separation roller 38.
[0029] Here, the less the reversing torque of torque limiter 42 is
made small, the less the press fitting force setting range of paper
supply roller 37 is narrowed. However, the press fitting force of
paper supply roller 37 by a load of weight 40 can be maintained at
a constant level irrespective of secular change or change from wear
of paper supply roller 37 and separation roller 38. Accordingly,
when paper supply roller 37 is press contacted by a load of weight
40, it becomes possible to make a reversing torque of torque
limiter 42 small.
[0030] For example, when a reversing torque range of torque limiter
42 is set at 380 to 450 (gf.cm) in FIG. 5, a press fitting force of
paper supply roller 37 is restricted to 360 to 440 (gf) and an area
for good separation/conveying of sheets of paper P becomes an area
(.delta.) enclosed by the one-dot chain line shown in FIG. 5.
Accordingly, it is advisable to set a weight of weight 40 so that a
press fitting force of paper supply roller 37 to separation roller
38 comes in the (.delta.) area. For example, when an own weight of
paper supply shaft 37a is 40 (g) and that of paper supply roller 37
is 20 (g), it is sufficient to set weight 40 at 400 to 500 (g).
[0031] Next, actions of the image forming apparatus will be
described. When the image forming process starts, a document is
read in scanner unit 6. In developing image forming unit 2, and
after uniformly charged by charging device 12 according to its
rotation in the arrow direction q, photosensitive drum 11 is
applied with laser beam corresponding to a document image and an
electrostatic latent image is formed thereon. Then, the
electrostatic latent image is developed in developing unit 14 and a
toner image is formed on photosensitive drum 11.
[0032] On the other hand, in cassette mechanism 3 or manual paper
supplying mechanism 4, specified sheets of paper P is taken out
with pick-up roller 30a to 30d or manual pick-up roller 4b. Sheets
of paper P taken out from paper supply tray 4a is separated and
conveyed in the direction of alignment roller 33 by manual
separation roller 4c. Sheets of paper P taken out from paper supply
cassettes 3a to 3d are separated to one by one while passing
through separation/conveying devices 31a to 31d with paper supply
roller 37 applied with a fixed load by weight 40 kept press
contacted and conveyed in the direction of aligning roller 33.
[0033] After the leading edges are aligned by aligning roller 33,
sheets of paper P are conveyed to the position of transfer charger
16 in synchronous with a toner image on photosensitive drum 11 and
then, separated from photosensitive drum 11 by separation charger
17 after a toner image is transferred. After sheets of paper P are
separated, photosensitive drum 11 is cleaned by removing residual
toner with cleaner unit 18, residual charge is eliminated with
charge elimination LED 19 and stands to next image forming process.
Sheets of paper P with an unfixed toner image formed thereon and
separated from photosensitive drum 11 are inserted between a heat
roller 20 and a press roller 21 of an fixing device 22 and a toner
image is heated, pressurized and fixed.
[0034] While sheets of paper P taken out from cassette mechanism 3
or manual paper supply mechanism 4 are separated and conveyed,
paper supply roller 37 and separation roller 38 are worn away.
However, even when paper supply roller 37 and separation roller 38
are worn, a load applied to paper supply roller 37 by weight 40 is
kept at a constant level. Therefore, a press fitting force of paper
supply roller 37 to separation roller 38 remains at 360 to 440 (gf)
at the initial stage shown in an area .delta. enclosed with the
one-dot chain line in FIG. 5 irrespective of wear of paper supply
roller 37 and separation roller 38, and sheets of paper P are
separated and conveyed certainly.
[0035] According to this first embodiment, paper supply roller 37
is press contacted to separation roller 38 using weight 40 of which
load to paper supply roller 37 does not change and a press fitting
force between paper supply roller 37 and separation roller 38
remains unchanged at the same level as that at the initial stage
irrespective of secular change and wear of paper supply roller 37
and separation roller 38. Accordingly, separation/conveying devices
31a to 31d are able to separate and convey sheets of paper P
certainly for an extended period irrespective of wear of paper
supply roller 37 and separation roller 38. Further, because a
reversing torque of torque limiter 42 can be made small, it becomes
possible to use a small, light and low price torque limiter 42.
[0036] Next, a second embodiment of this invention will be
explained. In this second embodiment, the paper supply roller is
loaded differently from the load in the first embodiment.
Therefore, in the second embodiment, the same component elements as
those in the first embodiment are assigned with the same reference
numerals and detail explanations thereof will be omitted here. In
this embodiment, a weight 53 is attached to the oscillation side of
paper supply shaft 37a as shown in FIG. 6. Further, weight 53 is
pressed in the direction of separation roller 38 by an auxiliary
pressing mechanism 54 that is an elastic member having an auxiliary
compressing lever 54a and an auxiliary compressing spring 54b.
[0037] Accordingly, paper supply roller 37 is compressed against
separation roller 38 by own weight and a load of weight 53 and
further, by the compressing force of auxiliary compressing
mechanism 54. When it is tried to generate a press fitting force of
paper supply roller 37 to separation roller 38 only by it's own
weight of paper supply roller 37 and a load of weight 53, weight 53
becomes large in size and cost increase will result. So, in this
embodiment, a margin of change in press fitting force of paper
supply roller 37 to separation roller 38 is increased while the
apparatus is made small in size and light in weight to balance both
merits.
[0038] For example, in a conventional apparatus in which the press
fitting force of paper supply roller 37 to separation roller 38 is
generated only by a compression force of a compression spring and
it is necessary to set conditions for press fitting force with a
compression spring by fully considering variance in compression
force of a compression spring for its deterioration or wear of
paper supply roller 37 and separation roller 38.
[0039] Therefore, in the conventional apparatus described above, it
is necessary to secure the press fitting force by a compression
spring in the range of variance 360 to 440 (gf) largely from the
initial stage as shown in the area (.eta.) enclosed by the dotted
line in FIG. 7. Therefore, in the above-mentioned conventional
apparatus, a difference between the area (.eta.) and the
trapezoidal area (.gamma.) in which sheets of paper can be
separated and conveyed satisfactorily is small and therefore, there
is almost no margin in setting conditions for a compression spring
and a high accuracy is demanded in the manufacture or mounting of a
compression spring.
[0040] On the contrary, in this embodiment, for example, when 1/2
of the press fitting force of paper supply roller 37 to separation
roller 38 is generated by an own weight of paper supply roller 37
and a load of weight 53 and the remaining 1/2 is generated by the
compression force of auxiliary compression mechanism 54, the small
sized and light weight apparatus can be obtained as a result of
decrease in the weight of weight 53 and further, variance in press
fitting force of paper supply roller 37 caused by variance in
compression force of auxiliary compression spring 54b can be
reduced to 1/2.
[0041] As a result, when a range of variance of press fitting force
of paper supply roller 37 to separation roller 38 by auxiliary
compression spring 54b in this embodiment was verified, it was
found that the range of variance in press fitting force of paper
supply roller 37 by auxiliary compression spring 54b at the initial
stage could be reduced to 380 to 420 (gf) as shown in the hatched
area (.theta.) in FIG. 7. Accordingly, in this embodiment, a
difference between the area (.theta.) and the trapezoidal area
(.gamma.) that is an area for a good separation and conveyance is
large and a large margin can be secured when setting conditions for
auxiliary compression spring 54b, and the cost reduction can be
achieved for the reduction of manufacturing or mounting accuracy of
auxiliary compression spring 54b. Further, the cost reduction
resulting from the mitigation of spring constant of auxiliary
compression spring 54b also can be obtained.
[0042] Further, in the comparison of a conventional apparatus with
this embodiment, when a compression spring constant of a
conventional apparatus is assumed as Ko and a spring constant of
auxiliary compression spring 54b in this embodiment is assumed as
Ki, Ko>Ki. When a variation in the outer diameter of paper
supply roller 37 and separation roller 38 due to wear at the time
when paper supply roller 37 and separation roller 38 reached the
service life is assumed as .DELTA.R, the variance reduction effect
of press fitting force of paper supply roller 37 in this embodiment
against a conventional apparatus is expressed by
.DELTA.R.multidot.(Ko-Ki). That is, the variance of press fitting
force of paper supply roller 37 in this embodiment is surely
reduced more than conventional apparatus.
[0043] In this embodiment, sheets of paper P taken out from
cassette mechanism 3 by pick-up rollers 30a to 30d are separated to
each sheet when passing through separation/ conveying devices 31a
to 31d wherein paper supply roller 37 is press contacted to
separation roller 38, conveyed in the direction of aligning roller
33 and a toner image is formed.
[0044] Further, in separation/conveying devices 31a to 31d, the
side edge of weight 53 of paper supply shaft 37a is free and
therefore, paper supply roller 37 may damp when sheets of paper P
are separated and conveyed. However, in this embodiment, paper
supply roller 37 is pressed down in the direction of separation
roller 38 by auxiliary compression mechanism 54 via weight 53 and
therefore, paper supply roller 37 separates and conveys sheets of
paper P satisfactorily without causing the damping.
[0045] Thus, while sheets of paper P taken out from cassette
mechanism 3 are separated and conveyed, paper supply roller 37 and
separation roller 38 are worn in separation/convey devices 31a to
31d. The compression force of auxiliary compression spring 54b
changes for wear of paper supply roller 37 and separation roller 38
and furthermore, the press fitting force of paper supply roller 347
changes.
[0046] However, the effect of change in the compression force of
auxiliary compression spring 54b to the press fitting force of
paper supply roller 37 is reduced to 1/2 and even when paper supply
roller 37 and separation roller 38 are worn, until the press
fitting force of paper supply roller 37 exceeds the trapezoidal
area (.gamma.) that is an area for a good separation and conveying,
separation/conveying devices 31a to 31d separate and convey sheets
of paper P surely and the long life is obtained.
[0047] According to this second embodiment, the press fitting force
of paper supply roller 37 and separation roller 38 is generated by
both of a load of weight 53 and the compression force of auxiliary
compression mechanism 54. Therefore, weight 53 can be made small in
size and light in weight and cost reduction is achieved by
reduction of a spring constant of auxiliary compression spring 54b.
Furthermore, the range of variance of press fitting force of paper
supply roller 37b by auxiliary compression spring 54b at the
initial stage can be lowered and as a result, the cost reduction in
manufacturing or mounting of auxiliary compression spring 54b can
be achieved.
[0048] Further, the variance of press fitting force of paper supply
roller 37 by the change in compression force of auxiliary
compression mechanism 54 is suppressed to 1/2 and the long life of
separation/conveying devices 31a to 31d can be achieved
irrespective of secular change or wear of paper supply roller 37
and separation roller 38. In addition, the damping of paper supply
roller 37 can be prevented by auxiliary compression mechanism 54
and it becomes possible to separate and convey sheets of paper P
satisfactorily.
[0049] This invention is not restricted to the above-mentioned
embodiments but can be modified variously within the scope of this
invention. For example, size and material of the paper supply
roller and the separation roller are optional and the reversing
force of the torque limiter is also not restricted. Further, a size
of a weight is also optional. In addition, the paper supply roller
itself may be made heavier so as to generate a press fitting force
between the paper supply roller and the separation roller and the
paper supply roller itself may be used as a weight.
[0050] Further, when the dumping may be caused on the paper supply
roller in the first embodiment, the weight and the paper supply
shaft can be made light using a sponge, a hydraulic damper, etc.
Further, in the second embodiment, a rate of press fitting force
that is generated in the paper supply roller by the weight and the
auxiliary compression mechanism is not restricted. Further, the
auxiliary compression mechanism may be provided at the separation
roller side and a press fitting force required between the paper
supply roller and the separation roller may be generated by a press
fitting force from the paper supply roller side for own weight of
paper supply roller 37 and a load of weight 53 and a press fitting
force by the compression force of the auxiliary compression
mechanism at the separation roller side.
[0051] As described above in detail, according to this invention, a
press fitting force between the paper supply roller and the
separation roller generated by a load of the weight remains
unchanged from the initial stage when the paper supply roller and
the separation roller are press fitted using a weight to apply a
fixed load to the paper supply roller, and it becomes possible to
separate and convey sheets of paper by the paper supply roller and
the separation roller certainly for an extended period irrespective
of secular change or wear of the paper supply roller and the
separation roller.
[0052] Further, when a press fitting force is generated between the
paper supply roller and the separation roller using an elastic
member in addition to a load of the weight, the press fitting force
of the paper supply roller is affected by the compression force of
the elastic member or wear of the paper supply roller and the
separation roller but the press fitting force of the paper supply
roller by a load of the weight is not changed and the variance of
press fitting force of the paper supply roller can be reduced as a
whole and the life of the separation and conveying function of
sheets of paper by the paper supply roller and the separation
roller can be extended.
* * * * *