U.S. patent application number 10/893974 was filed with the patent office on 2005-06-23 for paper conveyance apparatus for an image forming apparatus and a method thereof.
Invention is credited to Ahn, Byung-sun, Kim, Young-min, Park, Sang-cheol.
Application Number | 20050133982 10/893974 |
Document ID | / |
Family ID | 34675820 |
Filed Date | 2005-06-23 |
United States Patent
Application |
20050133982 |
Kind Code |
A1 |
Kim, Young-min ; et
al. |
June 23, 2005 |
Paper conveyance apparatus for an image forming apparatus and a
method thereof
Abstract
A paper conveyance apparatus and method for an image forming
apparatus are disclosed. The paper conveyance apparatus and method
provide an improved structure in which when the distance between
the conveyance roller shaft and the reversible roller shaft is
shortened due to the abrasion of the reversible roller, the center
of a gear train which transmits a driving force to the reversible
roller is swung to move as much as the shortened distance so that
the reversible roller can be continuously in contact with the
conveyance roller. The paper conveyance apparatus and method
comprise a conveyance roller for conveying a paper sheet to an
image forming section, a reversible roller for contacting the
conveyance roller, a driving motor having a driving gear for
supplying a driving force to the reversible roller, and an idle
gear for transmitting a driving force from the driving motor to the
reversible roller. The center of rotation of the idle gear is
movable according to the degree of abrasion of the reversible
roller in order to transmit a driving force from the driving motor
to the reversible roller.
Inventors: |
Kim, Young-min; (Suwon-si,
KR) ; Ahn, Byung-sun; (Suwon-si, KR) ; Park,
Sang-cheol; (Suwon-si, KR) |
Correspondence
Address: |
ROYLANCE, ABRAMS, BERDO & GOODMAN, L.L.P.
1300 19TH STREET, N.W.
SUITE 600
WASHINGTON,
DC
20036
US
|
Family ID: |
34675820 |
Appl. No.: |
10/893974 |
Filed: |
July 20, 2004 |
Current U.S.
Class: |
271/122 |
Current CPC
Class: |
B65H 2404/143 20130101;
B65H 2601/121 20130101; B65H 2404/1441 20130101; B65H 5/06
20130101 |
Class at
Publication: |
271/122 |
International
Class: |
B65H 003/52 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 18, 2003 |
KR |
2003-93183 |
Claims
What is claimed is:
1. A paper conveyance apparatus for an image forming apparatus,
comprising: a conveyance roller for conveying a paper sheet to an
image forming section; a reversible roller for contacting the
conveyance roller; a driving motor having a driving gear for
supplying a driving force to the reversible roller; and an idle
gear for transmitting a driving force from the driving motor to the
reversible roller, wherein the center of rotation of the idle gear
is movable according to the degree of abrasion of the reversible
roller in order to transmit a driving force from the driving motor
to the reversible roller.
2. The paper conveyance apparatus according to claim 2, wherein the
idle gear is movable along a track which is a part of the
circumference of a virtual circle having a radius corresponding to
a distance between the center of the driving gear and the center of
the idle gear.
3. The paper conveyance apparatus according to claim 2, wherein a
central shaft of the idle gear is movable along a swing slot formed
on one sidewall of the image forming apparatus to correspond to the
swing track of the idle gear.
4. The paper conveyance apparatus according to claim 3, wherein the
swing slot has an inner periphery with a curvature corresponding to
the swing track of the idle gear.
5. The paper conveyance apparatus according to claim 3, wherein the
swing slot is formed in a direction of a tangent to a virtual
circle having a radius corresponding to the distance between the
center of the driving gear and the center of the idle gear.
6. The paper conveyance apparatus according to claim 5, wherein the
swing slot comprises an elastic member for elastically supporting
the central shaft of the idle gear.
7. A method of feeding paper in an image forming apparatus,
comprising: conveying a paper sheet to an image forming section via
a conveyance roller; contacting the conveyance roller via a
reversible roller; supplying a driving force to the reversible
roller via a driving motor having a driving gear; and transmitting
a driving force from the driving motor to the reversible roller via
an idle gear, wherein the center of rotation of the idle gear is
movable according to the degree of abrasion of the reversible
roller in order to transmit a driving force from the driving motor
to the reversible roller.
8. The method according to claim 7, wherein the idle gear is
movable along a track which is a part of the circumference of a
virtual circle having a radius corresponding to a distance between
the center of the driving gear and the center of the idle gear.
9. The method according to claim 8, further comprising: providing a
central shaft of the idle gear which is movable along a swing slot
formed on one sidewall of the image forming apparatus to correspond
to the swing track of the idle gear.
10. The method according to claim 9, wherein the swing slot has an
inner periphery with a curvature corresponding to the swing track
of the idle gear.
11. The method according to claim 9, wherein the swing slot is
formed in a direction of a tangent to a virtual circle having a
radius corresponding to the distance between the center of the
driving gear and the center of the idle gear.
12. The method according to claim 11, wherein the swing slot
comprises an elastic member for elastically supporting the central
shaft of the idle gear.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit under 35 U.S.C. .sctn.
119(a) of Korean Application No. 2003-93183, filed Dec. 18, 2003,
in the Korean Intellectual Property Office, the entire contents of
which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to an image forming apparatus.
More particularly, the present invention relates to a paper feeder
and method for an image forming apparatus, for reducing the
malfunction caused by abrasion of a reversible roller that rotates
forwards and backwards in contact with a conveyance roller so that
paper sheets are picked up one by one.
[0004] 2. Description of the Related Art
[0005] FIG. 1 is a diagram illustrating a conventional
electrophotographic image forming apparatus 1 which feeds a paper P
using a knock-up plate type of a feeding device 2. As shown in FIG.
1, a paper P is picked up by a pickup roller. A conveyance
apparatus 10 having a plurality of rollers is provided to prevent
the simultaneous feeding of two or more paper sheets.
[0006] As shown in FIG. 2, the conveyance apparatus 10 consists of
a conveyance roller 11 and a reversible roller 12. A torque limiter
13 is mounted on the same axis of the reversible roller 12. Also, a
reversible motor (not shown) for reversely rotating the reversible
roller 12 is provided independently from a driving device for
rotating the conveyance roller 11.
[0007] The reversible roller 12 rotates in an opposite direction to
the conveyance roller 11. When two or more paper sheets are fed at
once, the reversible roller 12 separates the top paper sheet from
the underlying paper sheets using a difference in the coefficient
of friction between the reversible roller 12 and the conveyance
roller 11. When a single paper sheet is fed, the friction force
between the conveyance roller 11 and the reversible roller 12
becomes greater than a predetermined torque of the coaxial torque
limiter 13, thereby making the reversible roller 12 rotate in the
same direction of the rotation of the conveyance roller 11. A
reversible gear 14 is also mounted on the same axis of the
reversible roller 12 to receive a driving force from the reversible
motor. The reversible gear 14 rotates in a direction opposite to
the direction of rotation of the torque limiter 13, and operates
independently from the rotation of the conveyance roller 11.
[0008] The conveyance roller 11 and the reversible roller 12
comprise a rubber having a predetermined solidity, friction
coefficient and durability, such as a Natural Rubber (NR), an
Acrylonitrile Butadiene Rubber (NBR), an Ethylene-Proplyene-Diene
(EPDM), a urethane or a silicon.
[0009] Since the reversible roller 12 rotates in the opposite
direction to a paper feeding direction, the surface of the
reversible roller 12 contacting the conveyance roller 11 is apt to
be easily abraded. As the surface of the reversible roller 12
becomes abraded, a conveyance roller shaft S1 and a reversible
roller shaft S2 are not maintained in parallel with each other but
form an incline, as shown in FIG. 2. This problem results from the
fixed position of the reversible gear 14. When the conveyance
roller shaft S1 and the reversible roller shaft S2 are not in
parallel with each other, the conveyance roller 11 and the
reversible roller 12 do not contact sufficiently to separate two or
more paper sheets fed together and smoothly feed the paper sheets
sequentially. Accordingly, the abrasion of the reversible roller 12
may cause errors in the operation of the image forming
apparatus.
SUMMARY OF THE INVENTION
[0010] An aspect of the present invention is to solve at least the
above problems and to provide at least the advantages described
below. Accordingly, an aspect of the present invention is to
provide a paper feeder and method for an image forming apparatus,
having an improved structure to reduce the malfunction caused by
abrasion of a reversible roller that rotates forwards and backwards
in contact with a conveyance roller so that paper sheets are picked
up sequentially.
[0011] In order to achieve the above-described aspects of the
present invention, there is provided a paper feeder and method for
an image forming apparatus. The paper feeder and method comprise a
conveyance roller, a reversible roller, a driving motor and an idle
gear. The conveyance roller and the reversible roller, being in
contact with each other, rotate in the same direction as or the
opposite direction to a direction of paper feed to convey paper
sheets to an image forming section, separating paper sheets which
are fed together. The reversible roller is transmitted with a
driving force by the driving motor which is separate from the
conveyance roller. In order to transmit the driving force, a gear
train including an idle gear is used. The center of rotation of the
idle gear is movable so that a contacting force between the
conveyance roller and the reversible roller can be kept over a
predetermined level even when the reversible roller is abraded.
[0012] The idle gear is preferable movable along a track which is a
part of the circumference of a virtual circle having a radius
corresponding to the distance between the center of the driving
gear and the center of the idle gear.
[0013] The central shaft of the idle gear may move along a swing
slot formed on one sidewall of the image forming apparatus to
correspond to the swing track of the idle gear.
[0014] According to a first embodiment of the present invention,
the swing slot has an inner periphery with a curvature
corresponding to the curved swing track of the idle gear.
[0015] According to a second embodiment of the present invention,
the swing slot is formed in a direction of a tangent to a virtual
circle having a radius corresponding to the distance between the
center of the driving gear and the center of the idle gear. The
swing slot may include an elastic member for elastically supporting
the central shaft of the idle gear.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] The above and other aspects, features and advantages of the
present invention will become more apparent from the following
detailed description taken with the accompanying drawings in
which:
[0017] FIG. 1 is a diagram illustrating a conventional image
forming apparatus;
[0018] FIG. 2 is a diagram illustrating a state in which a
conveyance roller and a reversible roller of the conventional image
forming apparatus are inclined due to abrasion of the reversible
roller;
[0019] FIG. 3 is a diagram illustrating a state in which rotation
shafts of a conveyance roller and a reversible roller according to
an embodiment of the present invention move in response to the
abrasion of a reversible roller;
[0020] FIG. 4 is a diagram illustrating a sectional view of an
arrangement of gears, motors and shafts according to an embodiment
of the present invention;
[0021] FIG. 5 is a diagram illustrating a gear train of a
reversible roller according to a first embodiment of the present
invention; and
[0022] FIG. 6 is a diagram illustrating a gear train of a
reversible roller according to a second embodiment of the present
invention.
[0023] Throughout the drawings, it should be noted that the same or
similar elements are denoted by like reference numerals.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0024] Hereinafter, a few embodiments of a paper conveyance
apparatus and method for an image forming apparatus according to
embodiments of the present invention will now be described in
detail with reference to the accompanying drawings.
[0025] FIG. 3 is a diagram illustrating a paper feeder according to
an embodiment of the present invention.
[0026] As shown in FIG. 3, the conveyance apparatus 100 includes a
conveyance roller 110, and a reversible roller 120 pressed against
the conveyance roller 110 at a predetermined pressure. In order to
rotate the conveyance roller 110 and the reversible roller 120, a
conveyance gear 112 and a reversible gear 122 are provided to
receive a driving force from respective driving sources (not
shown).
[0027] A load regulator having a torque limiter T coaxial to the
reversible roller 120 is mounted on a reversible roller shaft 121.
The torque limiter T detects whether the friction force between the
conveyance roller 110 and the reversible roller 120 is reduced by a
paper sheet fed between the two rollers 110 and 120 to a level
below a predetermined friction coefficient. When a single paper
sheet is fed, the reversible roller 120 rotates in the same
direction as the conveyance roller 110 to convey the paper. When
two or more paper sheets are fed at once, the reversible roller 120
rotates in an opposite direction to the conveyance roller 110
according to a detection signal from the torque limiter T in order
to separate the fed paper sheets so that only the top paper sheet
is conveyed to an image forming section.
[0028] More specifically, a paper picked up by a pickup roller is
fed between the conveyance roller 110 and the reversible roller
120, and conveyed to the image forming section. If the friction
between the conveyance roller 110 and the reversible roller 120 is
greater than a predetermined coefficient of friction, the
reversible roller 120 rotates in the same direction of the rotation
of the conveyance roller 110. In contrast, if the friction is
smaller than the predetermined coefficient of friction, the
reversible roller 120 rotates in the opposite direction. The longer
the reversible roller 120 is used, the more it becomes abraded due
to friction with the conveyance roller 110. With the increase of
the abrasion of the reversible roller 120, the reversible roller
shaft 121 moves parallel by a distance `d` toward the conveyance
roller shaft 110 as shown in FIGS. 3 and 4. Therefore, in order to
continuously transmit a driving force to the reversible roller 120
from a driving motor 130 (FIG. 4), an idle gear 140 is required,
which flexibly moves to be kept in mesh with the reversible gear
122 even when the position of the reversible roller shaft 121 is
changed. As shown in FIG. 4, the central shaft Ci of the idle gear
140 is designed to be movable.
[0029] The central shaft Ci of the idle gear 140 moves along a
swing track A as shown in FIG. 4 to maintain the idle gear 140 and
the reversible gear 122 in mesh. The central shaft Ci of the idle
gear 140 is slidably mounted on one sidewall W (FIGS. 5 and 6) of
the image forming apparatus. When the reversible roller shaft 121
moves parallel toward the conveyance roller shaft 111, the central
shaft Ci also moves along the swing track A to maintain the idle
gear 140 and the reversible gear 120 in mesh. The swing track A may
be a part of the circumference of a virtual circle having a radius
corresponding to the distance between the central shaft Cm of the
driving gear 131 and the central shaft Ci of the idle gear 140.
[0030] FIGS. 5 and 6 are diagrams illustrating the idle gear 140
with the central shaft Ci movable along the swing track A according
to first and second embodiments of the present invention.
[0031] In accordance with the first embodiment of the present
invention, the central shaft Ci of the idle gear 140 is slidably
mounted on one sidewall W of the image forming apparatus. For this,
the sidewall W has a curved swing slot 141 having a curvature
corresponding to the swing track A and a width corresponding to the
diameter of the central shaft Ci. Accordingly, when the position of
the reversible roller shaft 121 is changed due to the abrasion of
the reversible roller 120, the central shaft Ci slides along the
swing slot 141 to maintain the idle gear 140 and the reversible
gear 122 in mesh.
[0032] As shown in FIG. 5, the curved swing slot 141 has a width
corresponding to the diameter of the central shaft Ci of the idle
gear 140. Also, the swing slot 141 has a curvature corresponding to
the curved swing track A.
[0033] According to the second embodiment of the present invention,
the central shaft Ci of the idle gear 140 is slidably mounted on
one sidewall W of the image forming apparatus. In this connection,
the sidewall W has a straight swing slot 142 formed in a direction
of a tangent to the swing track A, and having a width corresponding
to the diameter of the central shaft Ci. An elastic member 143 such
as a compression spring is mounted within the swing slot 142. The
elastic member 143 exerts an elastic restoring force so that the
idle gear 140 can be maintained in mesh with the reversible gear
122.
[0034] In the paper conveyance apparatus 100 for an image forming
apparatus according to the first and second embodiments of the
present invention, when the reversible roller 120 is abraded, the
reversible roller shaft 121 moves parallel toward the conveyance
roller 110 by a distance corresponding the abraded thickness of the
reversible roller 120, thereby preventing a biased abrasion of the
reversible roller 120 and any error of feeding plural paper sheets
at once.
[0035] When the distance between the conveyance roller shaft 111
and the reversible roller shaft 121 is shortened due to the
abrasion of the reversible roller 120, the idle gear 140 for
transmitting the driving force to the reversible roller 120 is
swung to move upward as much as the shortened distance so that the
reversible roller 120 can be constantly in contact with the
conveyance roller 110. Accordingly, by eliminating any causes of
biased abrasion of the reversible roller 120, reliability of the
image forming apparatus is ensured.
[0036] While the invention has been shown and described with
reference to certain embodiments thereof, it should be understood
by those skilled in the art that various changes in form and
details may be made therein without departing from the spirit and
scope of the invention as defined by the appended claims.
* * * * *