U.S. patent application number 11/882993 was filed with the patent office on 2008-01-24 for automatic document feeding apparatus.
Invention is credited to Won-Taek Kim.
Application Number | 20080018044 11/882993 |
Document ID | / |
Family ID | 34567802 |
Filed Date | 2008-01-24 |
United States Patent
Application |
20080018044 |
Kind Code |
A1 |
Kim; Won-Taek |
January 24, 2008 |
Automatic document feeding apparatus
Abstract
An automatic document feeding apparatus includes a shaft, an ADF
roller for feeding documents piece by piece by cooperating with a
separating member, and a power switching member for selectively
connecting a driving member with the shaft. The power switching
member is installed on the shaft. The ADF roller is also mounted on
the shaft such that the ADF roller can rotate by receiving a torque
only in a first direction.
Inventors: |
Kim; Won-Taek; (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: |
34567802 |
Appl. No.: |
11/882993 |
Filed: |
August 8, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10935166 |
Sep 8, 2004 |
7296790 |
|
|
11882993 |
Aug 8, 2007 |
|
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Current U.S.
Class: |
271/109 |
Current CPC
Class: |
B65H 3/0684 20130101;
B65H 2403/724 20130101 |
Class at
Publication: |
271/109 |
International
Class: |
B65H 3/06 20060101
B65H003/06 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 18, 2003 |
KR |
2003-81735 |
Claims
1. An automatic document feeding apparatus comprising: a shaft; an
ADF roller which feeds documents sheet by sheet by cooperating with
separating means, the ADF roller being mounted on the shaft such
that the ADF roller can rotate by receiving a torque only in a
first direction from the shaft; power switching means which
selectively connects driving means with the shaft, the power
switching means being installed on the shaft; and power coupling
means comprising a first coupling portion that slides axially on
the shaft to selectively couple the shaft to the ADF roller.
2. The automatic document feeding apparatus of claim 1, wherein the
power coupling means further comprises opposing saw tooth shape
members.
3. The automatic document feeding apparatus of claim 2, wherein the
power coupling means further comprises a spiral concave portion in
which a lever is inserted, the lever and spiral concave portions
cooperating to slide said first coupling portion to selectively
couple the shaft to the ADF roller.
4. An automatic document feeding apparatus comprising: a shaft; a
pickup roller rotated by receiving a torque from the shaft and
picking up a sheet of a document on a feeding base; a second shaft
on which the pickup roller is installed; an ADF roller to feed the
document picked up by the pickup roller; a separating member
engaged with the ADF roller to separate the document sheets
individually; and a bracket on which the pickup roller and ADF
roller are installed, and wherein the pickup roller rotates by
selectively receiving the torque only in a first direction from the
shaft.
5. The automatic document feeding apparatus of claim 4, wherein the
ADF roller rotates by selectively receiving a torque only in a
first direction from the shaft.
6. The automatic document feeding apparatus of claim 4, further
comprising: a first power coupling portion rotated by the torque; a
second power coupling portion installed on at least one of the ADF
roller and the pickup roller, the second power coupling portion
connected to the first power coupling portion; and wherein one of
the first power coupling portion and the second power coupling
portion slides to engage/separate with/from each other.
7. The automatic document feeding apparatus of claim 6, wherein
each of the first power coupling portion and the second power
coupling portion comprises a saw tooth defined by opposing sections
and incline sections to selectively connect with each other when
the shaft rotates in the first direction.
8. The automatic document feeding apparatus of claim 4, wherein
when the shaft rotates in the first direction, the torque of the
shaft is transferred to the bracket and when the shaft rotates in a
second direction, the torque of the shaft is not transferred to the
bracket.
9. The automatic document feeding apparatus of claim 8, wherein the
bracket is rotatable with respect to the shaft.
10. The automatic document feeding apparatus of claim 9, further
comprising an elastic member which biases the bracket to rotate in
the second direction.
Description
[0001] This application is a divisional application of co-pending
U.S. patent application Ser. No. 10/935,166, filed Sep. 8, 2004,
which claims benefit under 35 U.S.C. .sctn.119(a) of Korean Patent
Application No. 2003-81735, filed on Nov. 18, 2003, in the Korean
Intellectual Property Office, the entire disclosure of which is
incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to an automatic document
feeding apparatus. More particularly, the present invention relates
to an automatic document feeding apparatus having an automatic
document feeding (ADF) roller designed to transmit power only in
one direction.
[0004] 2. Description of the Related Art
[0005] Generally, a document feeding apparatus in a telecopy
machine, a copy machine, a scanner, and a digital compound machine
is used to feed documents stacked in a feeding base to reading
means for reading image information printed or written down on the
documents.
[0006] FIG. 1 shows a conventional automatic document feeding
apparatus. As shown in the drawing, a conventional automatic
document feeding apparatus includes a shaft 2 rotated by driving
means (not shown) connected to a gear 3, an ADF roller 3 installed
on the shaft 2, and separating means 4 for separating documents D
sheet by sheet. A feed roller 5 for feeding the documents at a
predetermined speed is provided on a front end of the ADF roller 3.
The feeding speed of the ADF roller 3 is identical to or less than
that of the feed roller 5. In general, the feeding speed of the ADF
roller 3 is slightly less than that of the feed roller 5.
Therefore, when the feed roller 5 starts feeding the documents D
fed to a feeding base 1 by the ADF roller 3, the document D may be
torn between the ADF roller 3 and the feed roller 5 due to the
difference in the feeding speed therebetween.
[0007] To solve this problem, a clutch (not shown) is provided in
the automatic document feeding apparatus. That is, when the shaft 2
rotates in a first direction where the document D is fed, the
clutch is engaged with the ADF roller 3 and transmits a torque to
the ADF roller 3, and when the shaft 2 rotates in a second
direction opposite to the first direction, the clutch is
disconnected from the ADF roller and the torque from the shaft 2 is
not transmitted. When the feed roller 5 starts feeding the document
D, the ADF roller 3 rotates faster than the shaft 2. At this point,
since the shaft 2 is disconnected from the ADF roller 3 by the
clutch, the ADF roller 3 can smoothly rotate in response to the
feeding speed of the feed roller 5.
[0008] In addition, while the feed roller 5 is feeding the document
D, the document D may be jammed. In this case, the jammed document
D may be removed by pulling a front end of the document D in a
direction A. At this point, the jammed document D is removed as the
ADF roller 3 smoothly slips on the shaft 2. Alternatively, in case
of pulling a rear end of the jammed document D to remove the jammed
document D, the clutch is operated in an opposite direction such
that the ADF roller 3 rotates the shaft 2 in the second direction.
At this point, since the shaft 2 is connected to the driving means
by a plurality of reduction gears, the ADF roller 3 rotates against
a relatively large amount of resistance. As a result, it becomes
difficult to remove the jammed document D, and, in the worst case,
the jammed document D may be torn.
[0009] The automatic document feeding apparatus may further include
a pickup roller 7 for picking up the document D and feeding the
same to the ADF roller 3. The pickup roller 7 contacts the document
D only when picking up the document D. That is, when the pickup
operation is completed, the pickup roller 7 moves away from the
document D. The pickup roller 7 is installed on a bracket 8
rotatably coupled on the shaft 2. In order to rotate the bracket 8,
the driving means should be designed to bi-directionally rotate.
However, the direction change of the driving means slows down the
document feeding speed, thereby reducing the number of documents
fed per unit of time.
SUMMARY OF THE INVENTION
[0010] Embodiments of the present invention provide an automatic
document feeding apparatus that can easily remove a jammed document
regardless of a pulling direction of the jammed document.
[0011] Also, embodiments of the present invention provide an
automatic document feeding apparatus that is designed to prevent
the reduction of the document feeding speed, which may be caused by
a direction change of the driving means.
[0012] According to an aspect of the present invention, there is
provided an automatic document feeding apparatus comprising a
shaft; an ADF roller which feeds documents sheet by sheet by
cooperating with separating means, the ADF roller being mounted on
the shaft such that the ADF roller can rotate by receiving a torque
only in a first direction from the shaft; and power switching means
which selectively connects driving means with the shaft, the power
switching means being installed on the shaft.
[0013] The automatic document feeding apparatus may further
comprise a pickup roller which picks up the documents stacked in a
feeding base by receiving the torque only in the first direction
from the shaft; a bracket rotatably mounted on the shaft, the
pickup roller being installed on the bracket; clutching means which
transmits the torque of the shaft to the bracket when the shaft
rotates in the first direction and does not transmit the torque of
the shaft to the bracket when the shaft rotates in a second
direction; and an elastic member which biases the bracket in the
second direction.
[0014] According to another aspect of the present invention, the
clutching means may comprise a clutch spring fitted on a first
cylindrical projection formed on the shaft and a second cylindrical
projection formed on the bracket by first fitting force to allow
the bracket to rotate in the first direction, the clutch spring
having a first end inserted in a first insertion groove provided on
the bracket; a clutch cover which encloses the clutch spring, the
clutch cover being provided with a second groove in which a second
end of the clutch spring is inserted and a circumferential
projection; and a stopper contacting the circumferential projection
so as to prevent the clutch spring from rotating in the second
direction.
[0015] The bracket may be provided with a plurality of the first
insertion grooves for adjusting the first fitting force, and the
clutch cover is provided with a plurality of the second insertion
grooves for adjusting the first fitting force.
[0016] The stopper may be provided on the bracket. The power
switching means is designed to disconnect the driving means with
the shaft when the document is jammed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] The above and other features and advantages of the present
invention will become more apparent by describing in detail
exemplary embodiments thereof with reference to the attached
drawings in which:
[0018] FIG. 1 is a schematic view of a conventional automatic
document feeding apparatus;
[0019] FIG. 2 is a view of an image information input system where
an automatic document feeding apparatus according to an embodiment
of the present invention is employed;
[0020] FIG. 3 is a perspective view of an automatic document
feeding apparatus according to an embodiment of the present
invention;
[0021] FIG. 4 is a sectional view illustrating a relationship
between a shaft and an electronic clutch used as power switching
means according to an embodiment of the present invention;
[0022] FIGS. 5 and 6 are views illustrating a relationship between
a shaft, a pickup roller and an ADF roller according to an
embodiment of the present invention;
[0023] FIG. 7 is an exploded perspective view of clutching means
according to an embodiment of the present invention;
[0024] FIGS. 8 and 9 are side views illustrating an operation of
clutching means depicted in FIG. 7; and
[0025] FIG. 10 is a view illustrating a relationship between a
shaft, pickup roller and ADF roller in the course of removing a
jammed document according to an embodiment of the present
invention.
[0026] In the drawings, like reference numbers are used to refer to
like features and structures.
DETAILED DESCRIPTION OF THE INVENTION
[0027] Embodiments of the present invention will now be described
more fully with reference to the accompanying drawings, in which
exemplary embodiments of the invention are shown. The invention
may, however, be embodied in many different forms and should not be
construed as being limited to the embodiments set forth herein;
rather, these embodiments are provided so that this disclosure will
be thorough and complete, and will fully convey the concept of the
invention to those skilled in the art. In the drawings, the
thicknesses of layers and regions are exaggerated for clarity.
[0028] FIG. 2 shows an image information input system where an
automatic document feeding apparatus of the present invention is
employed.
[0029] As shown in the drawing, there is shown an ADF roller 104
for feeding the documents D stacked in a feeding base 101 to a feed
roller 106 sheet by sheet by cooperating with a separating member
105. The separating member 105 is formed of a frictional member
biased on the ADF roller 104 by an elastic member. By a friction
difference between the ADF roller 104 and the document D, between
the documents D, and between the document D and the separating
member 105, the documents D can be fed sheet by sheet.
[0030] The reference numeral 107 indicates reading means for
reading image information printed or written down on the documents
D. A contact image sensor (CIS) or a charge coupled device (CCD)
may be used as the reading means, among other suitable devices.
Reference numerals 109A and 109B respectively indicate first and
second detecting sensors for detecting the documents D. That is,
the first detecting sensor 109A detects the documents D picked up
from the feeding base 101 to determine start timing for aligning a
front end of the document D on the feed roller 106. The second
detecting sensor 109B detects the front end of the document fed by
the feed roller 106 to determine start timing for reading the
document by the reading means 107. The second detecting sensor 109B
further detects a rear end of the document D to determine if the
discharge of the document D is completed. The reference numerals
108 and 102 respectively indicate a discharging roller and a tray
for stacking the documents D discharged by the discharging roller
108. For stable document feeding, a pickup roller 103 for picking
up the documents stacked in the feeding base 101 and feeding the
same between the ADF roller 104 and the separating member 105 may
be further provided. In Particular, when the feeding base 101 is
horizontally disposed, it is preferable that the pickup roller 103
be provided. Reference numeral 100 indicates driving means for
driving the feed roller 106, the ADF roller 104 and the pickup
roller 103.
[0031] FIG. 3 shows the automatic document feeding apparatus
according to an embodiment of the present invention.
[0032] As shown in the drawing, the shaft 110 is rotated by a
driving force transmitted from the driving means 100 via a
plurality of gears 41 and 42. Power switching means 120 is
installed on an end of the shaft 110. A bracket 130 is also
installed on the shaft 110. The reference numeral 140 indicates an
elastic member for biasing the bracket 130 in a second direction
302.
[0033] The power switching means 120 is designed to selectively
interconnect the driving means 100 and the shaft 110. An electronic
clutch is preferable as the power switching means.
[0034] FIG. 4 shows a relationship between the shaft 110 and the
electronic clutch used as the power switching means 120 according
to an embodiment of the present invention.
[0035] As shown in the drawing, the electronic clutch includes an
electromagnet 121 and a gear part 122 slightly spaced away from the
electromagnet 121 and rotatably installed on the shaft 110. The
gear part 122 is connected to the driving means 100 via the gears
41 and 42 (see FIG. 3). When a current is applied to the
electromagnet 121, the gear part 122 is attached on the
electromagnet 121 by electromagnetic force. Therefore, when the
driving means rotates, the electromagnet 121 rotates together with
the gear part 122. As shown in FIG. 4, since the electromagnet 121
is installed on a cut-away portion 112 of the shaft 110, the shaft
110 can rotate together with the electron magnet 121. When the
current being applied to the electron magnet 121 is cut off, the
gear part 122 moves away from the electromagnet 121. In this state,
when the driving means rotates, only the gear part 122 rotates
while the electromagnet 121 and the shaft 110 do not rotate.
[0036] The ADF roller 104 is rotatably installed on the shaft 110.
A second shaft 150 is fixedly or rotatably installed on the bracket
130. The pickup roller 103 is rotatably installed on the second
shaft 150. The ADF roller 104 and the pickup roller 103 are
designed to be subject to rotational force from the shaft 110 only
in a first direction 301 (a document feeding direction). That is,
the ADF roller 104 and the pickup roller 103 rotate in the first
direction 301 only when the shaft 110 rotates in the first
direction 301. When the shaft 110 rotates in the second direction
302, the ADF roller 104 and the pickup roller 103 do not
rotate.
[0037] Referring to FIG. 5, an exemplary structure is shown in
which the ADF roller 104 and the pickup roller 103 are designed to
receive a torque from the shaft 110 only in the first direction
301. A first member 210 is coupled on the shaft 110 to rotate
together with the shaft 110. The first member 210 is provided with
a gear portion 211, a lever portion 213 and a pin coupling portion
212. The shaft 110 is provided with a pin hole 113 in which a pin
118 having a length greater than a diameter of the shaft 110 is
inserted. When the first member 210 is pushed such that the pin 113
can be inserted in the pin coupling portion 213, the first member
210 is coupled to the shaft 110. Alternatively, the first member
210 may be forcedly fitted on the shaft 110. A gear 51 engaged with
the gear portion 211 is mounted on the bracket 130. Rotatably
coupled to the second shaft 150 are a second member 220 having a
gear part 221 engaged with the gear 51 and a lever portion 222.
Third members 230a and 230b are respectively coupled to the shaft
110 and the second shaft 150 to be capable of sliding in an axial
direction thereon. Each of the third members 230a and 230b is
provided with a first power coupling portion 231 formed in a saw
tooth shape defined by opposing sections 233 and inclined sections
234 and a spiral concave portion 232 in which the lever portion 213
(222) is inserted. Each of the ADF roller 104 and the pickup roller
103 is provided with a second power coupling portion 240
correspondingly engaged with the first power coupling portion 231,
the second power coupling portion 240 being formed in a saw tooth
shape defined by opposing sections 241 and inclined sections
242.
[0038] When the shaft 110 rotates in the first direction 301, the
first member 210 coupled on the shaft 110 by the pin 118 rotates in
the first direction 301 together with the shaft 110. The third
member 230a also rotates in the first direction 301 with the lever
portion 213 contacting an end portion of the spiral concave portion
232. The rotational force of the shaft 110 is transmitted to the
gear portion 221 of the second member 220 via the gear portion 211
and the gear 51. The second member 220 rotates in the first
direction 301 and the third member 230b also rotates in the first
direction 301 with the lever portion 222 contacting an end portion
of the spiral concave portion 232. At this point, when the third
members 230a and 230b rotate in the first direction 301, the
opposing sections 233 of the first power coupling portion 231 push
the opposing sections 241 of the second power coupling portion 240.
Accordingly, the ADF roller 104 and the pickup roller 103 rotate in
the first direction 301.
[0039] Referring to FIG. 6, when the shaft 110 rotates in the
second direction 302, all of the first to third members 210, 220,
and 230a and 230b rotate in the second direction 302, as a result
of which the inclined sections 234 of the first power coupling
portion 231 push the inclined sections 242 of the second power
coupling portions 240a and 240b. Therefore, the third members 230a
and 230b is pushed in an arrow direction 303 and thereby the first
power coupling portion 231 is separated from the second power
coupling portion 240. Accordingly, both the ADF roller 104 and the
pickup roller 103 do not rotate.
[0040] When the shaft 110 rotates in the first direction 301 again,
the lever portions 213 and 222 of the first and second members 210
and 220 push the spiral concave portions 232 of the third members
230a and 230b such that the third members 230a and 230b slide in
the direction of arrow 304 in FIG. 5, thereby the first power
coupling portion 231 is coupled to the second power coupling
portion 240. Accordingly, as shown in FIG. 5, both the ADF roller
104 and the pickup roller 103 rotate in the first direction
301.
[0041] In order to reduce load in the course of feeding the
documents D, the pickup roller 103 is preferably designed to
contact the documents only when it picks up the documents D. The
pickup roller 103 is installed on the bracket 130 rotatably mounted
on the shaft 110. Clutching means 250 is disposed between the
bracket 130 and the shaft 110 for transmitting rotational force of
the shaft 110 to the bracket 130 when the shaft rotates in the
first direction and for interrupting rotational force of the shaft
130 when the shaft 110 rotates in the second direction 302 so as
not to transmit the rotation force to the bracket 130.
[0042] FIG. 7 shows the clutching means 250 of FIG. 3 in detail. As
shown in the drawing, the bracket 130 is provided at a sidewall 131
with a first cylindrical projection 133 defining an insertion
portion 132 in which the shaft 110 is inserted. The bracket 130 is
further provided at the sidewall 131 with a first insertion portion
134 in which a first end 271 of a clutch spring 270 is inserted and
a stopper 135. The shaft 110 is provided with a pin hole 113. A
fourth member 260 provided with a second cylindrical projection 261
and a pin coupling portion 262 are inserted around the shaft 110.
The fourth member 260 is coupled on the shaft 110 through a
substantially identical manner to the first member 210 of FIGS. 5
and 6. Alternatively, the fourth member 260 may be forcedly fitted
around the shaft 110. A clutch cover 280 formed in a hollow shape
is disposed enclosing the clutch spring 270. The clutch cover 280
is provided with a second insertion groove 281 in which a second
end 272 of the clutch spring 270 is inserted and an outer
circumferential projection 282 contacting the stopper 135. The
clutch spring 270 is fitted on the first and second cylindrical
projections 133 and 261. Since an inner diameter of the clutch
spring 270 is less than outer diameters of the first and second
cylindrical projections 133 and 261, the clutch spring 270 is
inserted around the projections 133 and 261 while being slightly
widened. Therefore, the clutch spring 270 biases the first and
second cylindrical projections 133 and 261 using a first fitting
force.
[0043] When the shaft 110 rotates in a first direction, the
rotational force of the shaft 110 is transmitted to the first
cylindrical projection 133 by the first fitting force of the clutch
spring 270 via the second cylindrical projection 261. The first end
271 of the clutch spring 270 is inserted in the first insertion
groove 134 to push the bracket 130 in the first direction 301 (see
FIG. 3). Accordingly, as shown in FIG. 8, the bracket 134 rotates
in the first direction 301 and the pickup roller 103 contacts the
document D. The pickup roller 103 and the ADF roller 104 rotate in
the first direction 301 as described with reference to the FIG.
6.
[0044] The first fitting force of the clutch spring 270 should be
set such that it can rotate the bracket 130 in the first direction
301 while overcoming an elastic force of the elastic member 140
when the shaft 110 rotates in the first direction 301. To set the
first fitting force of the clutch spring in response to this
requirement, the bracket 130 and the clutch cover 280 may be
provided with a plurality of insertion grooves 134 and 281,
respectively. That is, by properly inserting the first and second
ends of the clutch spring 270 in the first and second insertion
grooves 134 and 281, respectively, the first fitting force can be
adjusted.
[0045] When the shaft 110 further rotates in the first direction
301 after the pickup roller 103 contacts the document D, the
bracket 130 is biased to further rotate in the first direction 301.
At this point, the first end 271 of the clutch spring 270 receives
repulsive force from the bracket 130 in the second direction 302.
At this point, the first fitting force of the clutch spring 270 is
reduced as the inner diameter of the clutch spring 270 is widened
in a moment. As a result, the clutch spring 270 slips on the first
cylindrical projection 133. Accordingly, even when the shaft 110
further rotates in the first direction 301 after the pickup roller
103 contacts the document D, the pickup roller 103 maintains its
gentle contacting state without applying excessive pressure to the
documents D.
[0046] When a predetermined time has elapsed after the front end of
the document D is detected by the first detecting sensor 109A, the
document D is fed by the feed roller 106. When the document D is
fed, since there is no need of rotating the shaft 110, the current
being applied to the power switching means 120 is cut off to
disconnect the driving means 100 from the shaft 110, thereby
stopping the rotation of the shaft 110. The bracket 130 rotates in
the second direction 302 by the elastic force of the elastic member
140 to separate the pickup roller 103 from the document D. At this
point, the first end 271 of the clutch spring 270 is pushed in the
second direction 302 while bracket 130 rotates in the second
direction 302. Then, the first fitting force of the clutch spring
270 is reduced as the inner diameter of the clutch spring 270 is
widened, and thereby the clutch spring 270 slips on the first
cylindrical projection 133. Accordingly, the bracket 130 smoothly
rotates in the second direction 302. As shown in FIG. 8, it is
preferable that there is provided suppressing means 160 for
suppressing the excessive rotation of the bracket 130 in the second
direction 302.
[0047] When the shaft 110 rotates in the first direction 301 by the
driving means 100, the bracket 130 rotates in the first direction
301 to allow the pickup roller 103 to contact the document D. The
document D picked up by the pickup roller 103 is fed sheet by sheet
while passing through between the ADF roller 104 and the separating
means 105. When a front end of the document D is advanced to the
feed roller 106, the document D is conveyed by the feed roller 106.
Accordingly, there is no need for bi-directionally rotating the
driving means 100 and preventing the delay of the feeding time,
which is incurred in the conventional automatic document feeding
apparatus.
[0048] A feeding speed of the ADF roller 104 is identical to or
less than that of the feed roller 106. In general, the feeding
speed of the ADF roller 104 is slightly less than that of the feed
roller 106. Therefore, to prevent the document D from being torn by
the difference in the feeding speed, since the ADF roller 104
should rotate in response to the feeding speed of the feed roller
106, the ADF roller 104 should be disconnected with the shaft 110.
Referring to FIG. 9, when the ADF roller 104 rotates in the first
direction 301 at the feeding speed identical to that of the feed
roller 106, the inclined sections 242 of the second power coupling
portion 240 push the inclined sections 234 of the first power
coupling portion 231 and the third member 230a is pushed in the
direction of arrow 303. As a result, the power connection between
the shaft 110 and the ADF roller 104 is cut off and the ADF roller
104 smoothly rotates in response to the feeding speed of the feed
roller 106.
[0049] To align the front end of the document D on the feed roller
106, the feed roller 106 does not rotate or rotates in the second
direction until the front end of the document D reaches thereto.
That is, in a state where the feed roller 106 is stopped or rotates
in the second direction 302, the document D is conveyed from the
first detecting sensor 109A to slightly over the feed roller 106
after the front end of the document D is detected by the first
detecting sensor 109A. As a result, as shown by a broken line 305
of FIG. 2, the document D is neatly curved and aligned on the feed
roller 106. In this state, when the feed roller 106 rotates in the
first direction 301, the document D is advantageously stably fed
without being skewed.
[0050] Power switching means that is identical to that shown in
FIG. 4 can be further provided on the feed roller 106. In this
case, the current applied to the power switching means can be cut
off to prevent the feed roller 106 from rotating while the document
D is being aligned on the feed roller 106. After the document
alignment is finished, the current is applied to the power
switching means to convey the document by rotating the feed roller
106.
[0051] For the automatic document feeding apparatus that does not
employ the aligning process, The ADF roller 104, the pickup roller
103 and the feed roller 106 are continuously rotated only in the
first direction 301. At this point, after the front end of the
document is inserted in the feed roller 106, the power switching
means disconnects the driving means 100 from the shaft 110. As a
result, the bracket 130 rotates in the second direction 302 by the
elastic force of the elastic member 140 to allow the pickup roller
103 to be separated from the document D and the ADF roller 104
rotates in response to the feeding speed of the feed roller
106.
[0052] When the document D is jammed while being conveyed, a jammed
location can be identified by checking the first and second
detecting sensors 109A and 109B. That is, when the front end of the
document D is not detected by the first detecting sensor 109A for a
predetermined time after the ADF roller 104 and the pickup roller
103 start rotating, it can be determined that the document D is
jammed between the ADF roller 104 and the feed roller 106. When the
front end of the document D is not detected by the second detecting
sensor 109B for a predetermined time after the front end of the
document D is detected by the first detecting sensor 109A, it can
be determined that the document D is jammed between the feed roller
106 and the reading means 107. When the rear end of the document D
is not detected by the second detecting sensor 109B for a
predetermined time after the front end of the document D is
detected by the second detecting sensor 109B, it can be determined
that the document D is jammed between the reading means 107 and the
discharging roller 108.
[0053] When it is determined that the document D is jammed between
the reading means 107 and the discharging roller 108, since this is
the case where the front end of the document D reaches the tray
102, the jammed document D can be removed by pulling the document D
in a direction A (FIG. 2). When it is determined that the document
D is jammed between the feed roller 106 and the reading means 107,
it is impossible to pull the front end of the document D in the
direction A. Accordingly, it is possible to remove the jammed
document D by pulling the rear end of the document D in a direction
B. When the document D is jammed between the ADF roller 104 and the
feed roller 106, it is possible to remove the jammed document D by
pulling the rear end of the document D in the direction B.
[0054] In more in detail, when the rear end of the jammed document
D is pulled in the direction B to remove the jammed document D
between the feed roller 106 and the reading means 107 or between
the ADF roller 104 and the feed roller 106, the ADF roller 104
rotates in the second direction 302. At this point, as shown in
FIG. 10, the opposing sections 241 of the second power coupling
portion 240 push the opposing sections 233 of the first power
coupling portion 231 in the second direction 302 and the third
member 230 rotates in the second direction 302. As a result, the
first member 210 and the shaft 110 also rotate in the second
direction 302. Here, the operation of the clutching means 250 for
selectively connecting the bracket 130 with the shaft 110 is
important. When the shaft 110 rotates in the second direction 302,
the bracket 130 cannot rotate in the second direction 302 by the
suppressing means 160. In this case, since the first end of the
clutch spring 270 is inserted in the first insertion groove 134, it
is twisted in a direction where the diameter thereof reduces,
thereby further biasing the first and second cylindrical
projections 133 and 261. As a result, the shaft 110 and the ADF
roller 104 cannot rotate in the second direction 302 as far as the
bracket 130 does not rotate in the second direction 302. Since the
document D is pressed between the ADF roller 104 and the separating
member 105, it is difficult to remove the document D if the ADF
roller 104 does not rotate. Therefore, when the document D is
pulled in the direction B by excessive force, the document D may be
torn.
[0055] However, in the present invention, when the shaft 110
rotates in the second direction 302, the second end of the clutch
spring 270 pushes the second insertion groove 281 to rotate the
clutch cover 280 in the second direction 302. At this point, since
the outer circumferential projection 282 of the clutch cover 280
contacts the stopper 135, the clutch cover 280 cannot rotate. In
this state, when the second end 272 of the clutch spring 270
continuously pushes the clutch cover 280 in the second direction
302, the inner diameter of the clutch spring 270 is widened. As a
result, since there is a slip between the second cylindrical
projection 261 and the clutch spring 270, the torque of the shaft
110 is not transmitted to the bracket 130. Accordingly, when the
jammed document D is pulled in the direction B, the jammed document
D can be easily removed while the ADF roller 104 and the shaft 110
smoothly rotate in the second direction 302. When the document D is
jammed, the driving means 100 is disconnected with the shaft 110 by
the power switching means 120. As a result, since only the ADF
roller 104 and the shaft 110 rotate, the jammed document D can be
more easily removed.
[0056] According to the above-described automatic document feeding
apparatus, the jammed document D can be easily removed and the
number of documents D fed per time can be increased.
[0057] While the present invention has been particularly shown and
described with reference to exemplary embodiments thereof, it will
be understood by those of ordinary skill in the art that various
changes in form and details may be made therein without departing
from the spirit and scope of the present invention as defined by
the following claims.
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