Information
-
Patent Grant
-
6601843
-
Patent Number
6,601,843
-
Date Filed
Friday, December 28, 200122 years ago
-
Date Issued
Tuesday, August 5, 200320 years ago
-
Inventors
-
Original Assignees
-
Examiners
- Walsh; Donald P
- Bower; Kenneth W
Agents
- Oblon, Spivak, McClelland, Maier & Neustadt, P.C.
-
CPC
-
US Classifications
Field of Search
US
- 271 401
- 271 407
- 271 408
- 271 41
- 271 1001
- 271 1004
- 271 1009
- 271 1011
- 271 1013
- 271 122
-
International Classifications
-
Abstract
A sheet feeding device including a sheet tray accommodating stacked sheets, and a sheet feeding unit feeding the stacked sheets in the sheet tray one by one. The sheet feeding unit includes a feeding roller which rotates in a sheet feeding direction, and a separation roller which presses against the feeding roller when feeding each of the stacked sheets and which rotates, via a torque limiter, in a direction opposite the sheet feeding direction. The separation roller is rotated by rotation of the feeding roller when a single sheet is sandwiched between the feeding and separation rollers. Also included is a conveying member arranged downstream of the feeding roller in the sheet feeding direction, and a driving source which drives each of the feeding roller, the separation roller, and the conveying member via a driving force transmission mechanism so the separation roller and the conveying member are driven in conjunction with each other.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
The present application claims priority and contains subject matter related to Japanese Patent Applications No. 2000-400698, and No. 2001-366526 filed in the Japanese Patent Office on Dec. 28, 2000 and Nov. 30, 2001, respectively, and the entire contents of which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a sheet feeding device for use in image forming apparatuses, such as copying machines, printers, facsimile apparatuses, printing apparatuses, etc., and an image forming apparatus using the sheet feeding device.
2. Discussion of the Background
In sheet feeding devices for image forming apparatuses, various methods have been proposed for separating stacked sheets so as to be fed one by one. A friction separation method is one of the well known methods. A sheet feeding device using a friction separation method generally includes a feeding roller which rotates in a sheet feeding direction, a separation roller which is pressed against the feeding roller and which is driven, via a torque limiter, to rotate in a direction opposite the sheet feeding direction, and a conveying roller arranged downstream of the feeding roller and the separation roller in the sheet feeding direction. When one sheet is sandwiched between the feeding roller and the separation roller, the separation roller is rotated by rotation of the feeding roller via the torque limiter, and when two or more sheets are sandwiched between the feeding roller and the separation roller, the sheets are separated from each other so as to be fed one by one because the separation roller is rotated in the opposite direction relative to the sheet feeding direction.
In a sheet feeding device using a friction separation method, driving a feeding roller, a separation roller and a conveying roller with individual driving sources is not desirable because of cost. Therefore, a feeding roller, a separation roller and a conveying roller is usually driven with a single driving source. Each of the rollers is connected or disconnected from the single driving source using, for example, an electromagnetic clutch and a solenoid. However, in an electric clutch, an inferior operation of the sheet feeding device may occur depending upon the amount of driving load for the connection and/or the disconnection, by variation in the periods of connection and/or disconnection of the driving source with each of the rollers with the electric clutch or by slippage in the clutch. This adversely influences the sheet conveying property of the sheet feeding device and causes sheet jamming in the sheet feeding device.
The above-described disadvantage in using an electric clutch in a sheet feeding device is addressed in Japanese Patent Laid-open Publication No. 8-59000. In JP No. 8-59000, a plurality of sheet feeding devices are provided in multiple-stages, and each of the sheet feeding devices includes an individual sheet feeding unit. Further, in the sheet feeding unit, a feeding roller, a separation roller, and a conveying roller are driven using a mechanical clutch (such as a one-way clutch) by switching a single reversible motor between forward and reverse directions. Specifically, the feeding, separation and conveying rollers are driven when the motor rotates in the forward direction, and only the conveying roller is driven at a high speed when the motor rotates in the reverse direction. Additionally, in the sheet feeding device of JP No. 8-59000, because the separation roller is stopped together with the feeding roller when rotation of the motor is reversed, if a subsequent sheet is stuck to a part of a sheet being fed (due to static electricity, etc.), the subsequent sheet may be fed together with the sheet being fed, resulting in a so-called double feeding of sheets.
SUMMARY OF THE INVENTION
Accordingly, one object of the present invention, is to solve the above-noted and other problems.
Another object of the present invention is to provide a novel sheet feeding device and image forming apparatus that includes a driving force transmitting mechanism that does not use an electric clutch and avoids double feeding of sheets.
To achieve these and other objects, the present invention provides a novel sheet feeding device including a sheet tray configured to accommodate stacked sheets, and a feeding unit configured to feed the stacked sheets in the sheet tray one by one. The sheet feeding unit includes a feeding roller configured to be driven to rotate in a sheet feeding direction in which each of the stacked sheets is fed, and a separation roller configured to be pressed against the feeding roller when feeding each of the sheets and to be driven to rotate, via a torque limiter, in a direction opposite the sheet feeding direction. The separation roller is rotated by rotation of the feeding roller in the sheet feeding direction when a single sheet of the stacked sheets is sandwiched between the feeding roller and the separation roller. The sheet feeding unit further includes a conveying member arranged downstream from the feeding roller in the sheet feeding direction, a driving source configured to drive the feeding roller, the separation roller, and the conveying member, and a driving force transmission mechanism configured to transmit a driving force to each of the feeding and separation rollers and the conveying member such that the separation roller and the conveying member are driven in conjunction with each other.
The present invention also provides an image forming apparatus using the above-noted sheet feeding device or a plurality of sheet feeding devices.
BRIEF DESCRIPTION OF THE DRAWINGS
A more complete appreciation of the present invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in conjunction with accompanying drawings, wherein:
FIG. 1
is a schematic drawing of an image forming apparatus including a plurality of sheet feeding devices according to a preferred embodiment of the present invention;
FIG. 2
is an enlarged schematic drawing of a sheet tray and a sheet feeding unit of each of the sheet feeding devices;
FIG. 3
is a schematic drawing of the sheet feeding unit;
FIG. 4
is a front view of the sheet feeding unit;
FIG. 5
is a schematic drawing illustrating an exemplary construction of the sheet feeding unit for detachably mounting the sheet feeding unit to a main body of the sheet feeding device;
FIG. 6
is schematic drawing for explaining a contacting/separating operation of a separation roller relative to a feeding roller in the sheet feeding device;
FIG. 7
is a perspective drawing illustrating an exemplary construction of a contact/separation device of the sheet feeding device to move the separation roller to contact and separate from the feeding roller;
FIG. 8
is a schematic drawing for explaining an operation of the contact/separation device;
FIG. 9
is a table indicating a driving state of each sheet feeding unit of multiple-staged sheet feeding devices when each of the sheet feeding devices is selected for sheet feeding;
FIG. 10
is a schematic drawing of a sheet feeding unit of the sheet feeding device according to another preferred embodiment of the present invention;
FIG. 11
is a front view of four sheet feeding devices arranged in multiple-stages in a vertical direction, each including the sheet feeding unit of
FIG. 10
;
FIG. 12
is a table indicating a driving status of each sheet feeding unit of the multiple-staged sheet feeding devices of
FIG. 11
; and
FIG. 13
is a schematic drawing of a sheet feeding unit of the sheet feeding device according to still another preferred embodiment of the present invention, which drives a feeding roller and a separation roller via a series of gears.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views, preferred embodiments of the present invention are described.
FIG. 1
is a schematic drawing of an image forming apparatus including a plurality of sheet feeding devices according to a preferred embodiment of the present invention. In
FIG. 1
, numeral
1
denotes a main body of the image forming apparatus, in which an image forming part
2
is provided. The image forming part
2
includes a photoconductor drum
3
as an image bearing member, and performs image formation according to a known electrophotography process.
Further, a sheet feeding part
10
including multiple-staged sheet feeding devices (four sheet feeding devices
11
,
12
,
13
and
14
in this embodiment), is arranged below the image forming part
2
to convey a sheet therefrom toward the image forming part
2
. In addition, a manual sheet feeding device
4
, and a sheet reversing unit
5
for forming images on both sides of a sheet are provided in the main body
1
of the apparatus.
In the above-described image forming apparatus, a sheet fed out from the sheet feeding part
10
or fed from the manual sheet feeding device
4
is conveyed to a registration roller
6
, and is then conveyed to a transfer part of the image forming part
2
by the registration roller
6
in synchronism with a timing that a toner image formed on a surface of the photoconductor drum
3
is moved to the transfer part.
Additionally, a transferring belt
7
is provided at the transfer part. The toner image is transferred onto the sheet conveyed to the transfer part by the transferring belt
7
, and at the same time the sheet is conveyed by movement of the transferring belt
7
to a fixing device
8
. The toner image is fixed onto the sheet at the fixing device
8
, for example, by a heat and pressure operation. The sheet is then selectively conveyed to a sheet discharging part
9
or to the reversing unit
5
.
FIG. 2
is an enlarged schematic drawing illustrating a sheet tray accommodating stacked sheets and a sheet feeding unit of each of the sheet feeding devices
11
-
14
of the sheet feeding part
10
.
FIG. 3
is a schematic drawing illustrating a driving force transmission mechanism of the sheet feeding unit.
Each of the sheet feeding devices
11
-
14
employs a friction separation method and includes, as illustrated in
FIGS. 1 and 2
, a sheet tray
20
configured to accommodate stacked sheets, and a sheet feeding unit
30
configured to feed the stacked sheets one by one. As shown in
FIG. 2
, the sheet feeding unit
30
includes a feeding roller
21
configured to be driven to rotate in a sheet feeding direction in which a sheet P is fed, a separation roller
22
configured to be pressed against the feeding roller
21
when feeding the sheet P and to be driven via a torque limiter (not shown in
FIG. 2
) to rotate in a sheet returning direction in which the sheet P is returned. Also included is a pick-up roller
23
arranged on the stacked sheets in the sheet tray
20
and configured to rotate in the sheet feeding direction to feed the sheet P from the sheet tray
20
, and a conveying roller
24
serving as a conveying member for further conveying the sheet P fed by the feeding roller
21
.
In each of the sheet feeding devices
11
-
14
, when starting a sheet feeding operation, the pick-up roller
23
(to which a driving force of the feeding roller
21
is transmitted) first feeds an uppermost sheet P of the stacked sheets in the sheet tray
20
in a direction indicated by an arrow A. The fed sheet P is then sandwiched between the feeding roller
21
and the separation roller
22
at a nip thereof. At this time, when the fed sheet P is a single sheet, the separation roller
22
is rotated by a conveying force of the feeding roller
21
so the sheet P is fed in the sheet feeding direction. The sheet P is further conveyed by the conveying roller
24
to the registration roller
6
.
When plural sheets P are fed between the feeding roller
21
and the separation roller
22
, the separation roller
22
rotates in the sheet returning direction because a predetermined torque is given to the separation roller
22
in the sheet returning direction. Thereby, the sheet P contacting the separation roller
22
is returned and only the uppermost sheet P of the plural sheets P is fed by the feeding roller
21
. In
FIG. 2
, numerals
27
and
28
denote driven conveying rollers contacting the conveying roller
24
.
Although only one sheet feeding unit
30
is illustrated in
FIG. 3
, it should be appreciated that a sheet feeding unit is included in each sheet feeding devices
11
-
14
. Further, the sheet feeding unit
30
includes, as illustrated in
FIG. 3
, a motor
31
serving as a driving source. In this embodiment, a stepping motor rotatable in two directions (i.e., first and second directions) is used for the motor
31
. A driving force of the motor
31
is transmitted via a driving force transmission mechanism (described below) to the feeding roller
21
, the separation roller
22
, and the conveying roller
24
. In addition, the feeding, separation and conveying rollers
21
,
22
and
24
are supported by a frame
29
(see
FIG. 2
) of the sheet feeding unit
30
.
Now, referring to
FIG. 3
, the driving force transmission mechanism of the sheet feeding unit
30
will be described. As shown, a timing pulley
35
is provided to an output axis
32
of the motor
31
, a timing pulley
36
having a gear
39
is provided to a driving axis
33
of the feeding roller
21
, a timing pulley
37
is provided to a driving axis
34
of the separation roller
22
, and a timing belt
38
is spanned around the timing pulleys
35
,
36
and
37
. Further, as shown in
FIG. 4
, the timing belt
38
is spanned around the timing pulleys
35
,
36
and
37
in a triangle when viewed from the front of the image forming apparatus.
With reference to
FIGS. 3 and 4
, a driving force of the motor
31
is conveyed from the timing pulley
35
, via the timing belt
38
and the timing pulley
36
having a gear
39
, to the driving axis
33
of the feeding roller
21
, and from the timing pulley
35
, via the timing belt
38
and the timing pulley
37
, to the driving axis
34
of the separation roller
22
. In
FIG. 3
, numeral
25
denotes a torque limiter.
In addition, one-way clutches
36
a
and
37
a
are provided to the timing pulley
36
having the gear
39
and to the timing pulley
37
, respectively. Further, a gear
40
engaging with the gear
39
of the pulley
36
is provided to the driving axis
34
of the separation roller
22
, and a one-way clutch
40
a
is provided to the gear
40
. The one-way clutch
36
a
is configured to be locked relative to a direction in which the timing belt
38
is rotated when the motor
31
is driven to rotate in the first direction (hereinafter, the forward direction), so that a driving force of the motor
31
is transmitted. In this rotation direction of the timing belt
38
, the one-way clutch
37
a
does not transmit the driving force of the motor
31
. Further, the one-way clutch
40
a
transmits the driving force of the motor
31
when the driving axis
33
of the feeding roller
21
is rotated by driving the motor
31
to rotate in the forward direction.
Accordingly, when the motor
31
is driven to rotate in the forward direction, the driving axis
33
of the feeding roller
21
is driven to rotate via the output axis
32
, the timing belt
38
, and the pulley
36
having the gear
39
. Further, the driving force of the motor
31
is transmitted to the driving axis
34
of the separation roller
22
via the pulley
36
having the gears
39
and
40
. In addition, when the motor
31
is driven to rotate in the forward direction, the one-way clutch
37
a
is idle. Therefore, the driving force of the motor
31
is not transmitted to the driving axis
34
of the separation roller
22
via the timing pulley
37
. Accordingly, when the motor
31
is driven to rotate in the forward direction, the feeding roller
21
and the separation roller
22
are both driven to rotate. The first driving force transmission route according to this embodiment includes the route in which the driving force of the motor
31
is transmitted to the driving axis
34
of the separation roller
22
via the timing belt
38
and timing pulley
36
having the gears
39
and
40
.
When the motor
31
is driven to rotate in the second direction (hereinafter, the reverse direction), in the direction in which the timing belt
38
moves at this time, the one-way clutch
36
a
does not transmit a driving force of the motor
31
, so the driving axis
33
of the feeding roller
21
does not rotate. On the other hand, because the one-way clutch
37
a
of the driving axis
34
of the separation roller
22
transmits the driving force of the motor
31
at that time, the driving force of the motor
31
is transmitted via the timing belt
38
and the timing pulley
37
to the driving axis
34
of the separation roller
22
, so the separation roller
22
is driven to rotate.
At this time, because the one-way clutch
40
a
does not transmit a driving force of the driving axis
34
, the gear
40
does not rotate and thus a rotation of the driving axis
34
of the separation roller
22
is never transmitted to the driving axis
33
of the feeding roller
21
via the gear
40
and the timing pulley
36
having the gear
39
. Here, a second driving force transmission route according to the embodiment includes the route in which a driving force of the motor
31
is transmitted to the driving axis
34
of the separation roller
22
via the timing belt
38
and the timing pulley
37
.
Thus, the driving axis
33
of the feeding roller
21
is configured to be driven to rotate only when the motor
31
rotates in the forward direction, and the driving axis
34
of the separation roller
22
is configured to be driven to rotate when the motor
31
rotates in either of the forward and reverse directions. Further, a gear
41
is provided to the driving axis
34
of the separation roller
22
, and the gear
41
engages with a gear
42
provided to a driven axis
43
to which the separation roller
22
is mounted. By configuring the separation roller
22
as described above (i.e., by providing the separation roller
22
to the driven axis
43
instead of the driving axis
34
and connecting the driven axis
43
and the driving axis
34
with the gears
41
and
42
), a separation pressure of the separation roller
22
relative to the feeding roller
21
may be adjusted by adjusting gear surface pressures of the gears
41
and
42
.
In addition, a timing pulley
44
is provided to the driving axis
34
of the separation roller
22
, and a gear
48
which engages with a gear
47
of a timing pulley
46
having a gear is provided to a roller axis
45
of the conveying roller
24
. Further, a timing belt
49
is spanned around the timing pulley
44
and the timing pulley
46
having a gear. Thus, the conveying roller
24
rotates when the driving axis
34
of the separation roller
22
is driven to rotate. Accordingly, when the separation roller
22
is driven, the conveying roller
24
is driven to rotate.
Therefore, in each of the sheet feeding devices
11
-
14
having the sheet feeding unit
30
, when a sheet feeding instruction is given, the motor
31
is rotated in the forward direction, and thereby the feeding roller
21
, the separation roller
22
, and the conveying roller
24
are driven to rotate in predetermined directions, respectively. Further, the pick-up roller
23
connected with the driving axis
33
of the feeding roller
21
via an idle gear (not shown) is driven to rotate in a predetermined direction with the forward rotation of the motor
31
.
After a sheet fed by the pick-up roller
23
is separated from other sheets by the feeding roller
21
and the separation roller
22
, the sheet is conveyed by the conveying roller
24
. Once a sheet has been fed to the conveying roller
24
, the sheet can be conveyed without driving the feeding roller
21
to rotate by rotating the conveying roller
24
. Driving the feeding roller
21
should preferably be stopped while a sheet is sandwiched by the feeding roller
21
and the separation roller
22
. Therefore, in this embodiment, as illustrated in
FIG. 2
, a sensor
26
is arranged downstream of the conveying roller
24
in the sheet conveying direction and in the vicinity thereof, so that when the sensor
26
detects a leading edge of the sheet, the direction of rotation of the motor
31
is switched from the forward direction to the reverse direction.
When the motor
31
is driven to rotate in the reverse direction, as described above, the feeding roller
21
is not driven to rotate, but the separation roller
22
and the conveying roller
24
continue to be driven until the sheet passes the conveying roller
24
. Thus, the separation roller
22
and the conveying roller
24
are driven to rotate in conjunction with each other during a sheet feeding operation. Thus, even if a subsequent sheet is stuck to a part of the sheet to be fed by static electricity, etc., the subsequent sheet is returned by the separation roller
22
, thereby preventing double feeding of sheets. Further, driving the separation roller
22
and the conveying roller
24
in conjunction with each other can be performed using individual driving sources (motors). However, it is advantageous to drive the separation roller
22
and the conveying roller
24
with a single driving source as in the above-described embodiment because of lower costs and a smaller driving source. Further, the one-way clutch
48
a
is provided to the gear
48
, so that when the gear
48
rotates, rotation of the gear
48
is transmitted to the axis
45
of the conveying roller
24
. Accordingly, even if the conveying roller
24
rotates via a sheet being conveyed, the rotation of the conveying roller
24
is not transmitted to the gear
48
. In addition, the sheet feeding unit
30
is detachably mounted to each main body of the sheet feeding devices
11
-
14
allowing for simplified maintenance, etc.
Turning now to
FIG. 5
, which illustrates an exemplary construction of the sheet feeding unit
30
for detachably mounting the sheet feeding unit
30
to each main body of the sheet feeding devices
11
-
14
. As illustrated in
FIG. 5
, the frame
29
of the sheet feeding unit
30
includes a front plate part
29
a
and a rear plate part
29
b
. An L-shaped mounting metal
70
is fixed to the front plate part
29
a
and two pins
71
and
72
are fixed to the rear plate part
29
b
extending in the axial direction of the feeding roller
21
. A rear side plate
75
and a front side plate
76
are provided to the main body of the sheet feeding unit
30
, and holes
77
and
78
are formed in the rear side plate
75
so the pins
71
and
72
are inserted therein respectively. The hole
77
is formed in an elongated form in a horizontal direction, screw holes
73
are formed in the mounting metal
70
for screw bolts
74
, and screw holes (not shown) are formed in the front side plate
76
at positions corresponding to the screw holes
73
.
Additionally, the sheet feeding unit
30
is supported by the rear side plate
75
with the pins
71
and
72
inserted into the holes
77
and
78
at the rear side of each of the sheet feeding devices
11
-
14
, and at the front side by the front side plate
76
with the screw bolts
74
inserted into the screw holes
73
of the mounting metal
70
and the corresponding screw holes of the front side plate
76
. Accordingly, when removing the sheet feeding unit
30
from each of the sheet feeding devices
11
-
14
, the screw bolts
74
are first removed, and then the sheet feeding unit
30
is moved in a direction indicated by an arrow B, so the sheet feeding unit
30
is swung substantially around the pin
72
.
After the sheet feeding unit
30
is moved to a position where the sheet feeding unit
30
does not interfere with the front side plate
76
, the sheet feeding unit
30
may be removed from the corresponding sheet feeding device by drawing out the sheet feeding unit
30
in a direction indicated by an arrow C. Further, the hole
77
is formed in an elongated hole so the sheet feeding unit
30
can be easily swung in the direction indicated by the arrow B. The sheet feeding unit
30
can be attached to each of the sheet feeding devices
11
-
14
by performing the above-described procedures in the reverse order.
In the image forming apparatus of the present invention illustrated in
FIG. 1
, in which the sheet feeding devices
11
-
14
are arranged in multiple stages in a vertical direction, when a lower side sheet feeding device (for example, the sheet feeding device
14
) in the multiple stages feeds a sheet, the sheet cannot be conveyed to the image forming part
2
unless each of the conveying rollers
24
of the sheet feeding devices
11
,
12
, and
13
located above the lower side feeding device
14
is driven. In this instance, the pick-up roller
23
and the feeding roller
21
of each sheet feeding unit
30
of the sheet feeding devices
11
,
12
, and
13
should preferably not be driven to rotate.
In the above-described image forming apparatus according to a preferred embodiment of the present invention, the sheet feeding units
30
of the sheet feeding devices
11
-
14
are independent from each other. Thus, when the lowermost sheet feeding device
14
feeds a sheet, all of the sheet feeding devices
11
,
12
,
13
, and
14
are driven. At that time, the motor
31
of the sheet feeding unit
30
of the lowermost feeding device
14
, which feeds the sheet, is switched from being driven to rotate in the forward direction to being driven to rotate in the reverse direction. However, the motors
31
of the sheet feeding units
30
of the other three feeding devices
11
,
12
, and
13
are driven to rotate in the reverse direction from the start. By controlling the motor
31
of each of the sheet feeding units
30
of the sheet feeding devices
11
-
14
, a sheet fed from the lowermost sheet feeding device
14
is conveyed to the image forming part
2
.
In the image forming apparatus of the present invention illustrated in
FIG. 1
, each of the sheet feeding devices
11
-
14
also includes a contact/separation device to move the separation roller
22
in directions indicated by an arrow D in
FIG. 6
to contact and separate from the feeding roller
21
.
Turning now to
FIG. 7
, which is a schematic drawing illustrating an example of the contact/separation device, and
FIG. 8
which is a schematic drawing explaining an operation of the contact/separation device. In
FIGS. 7 and 8
, a pressing lever
80
presses the separation roller
22
to move toward the feeding roller
21
so the separation roller
22
contacts the feeding roller
21
by a pulling force of a pressing spring
81
. A releasing lever
90
releases the pressing force of the pressing lever
80
. The pressing lever
80
is rotatably attached to the frame (not shown) of the sheet feeding unit
30
via a supporting axis
82
.
An upwardly-pressing part
83
upwardly presses the separation roller
22
and a downwardly-pressing part
84
downwardly presses the separation roller
22
and are formed in the pressing lever
80
. The pressing spring
81
applies to the pressing lever
80
a rotational force in the clockwise direction in
FIG. 8
centering around the supporting axis
82
. The upwardly-pressing part
83
contacts a roller
53
a
fixed to the driven axis
43
of the separation roller
22
, so the pressing lever
80
presses the separation roller
22
.
In addition, the releasing lever
90
is rotatably mounted to the frame (not shown) of the sheet feeding unit
30
via a supporting axis
91
(see FIG.
7
), and is pressed by a releasing spring
92
to rotate around the supporting axis
91
in the counterclockwise direction in
FIG. 7. A
plunger
96
of a solenoid
95
is connected via a pin
97
with one end of the releasing lever
90
so as to be rotatable. Further, as illustrated in
FIG. 8
, the other end of the releasing lever
90
contacts a contact part
85
formed in the pressing lever
80
.
When the solenoid
95
is turned off, the releasing lever
90
presses the contact part
85
of the pressing lever
80
by an elastic force of the releasing spring
92
of the releasing lever
90
, and the downwardly-pressing part
84
of the pressing lever
80
contacts the driven axis
43
of the separation roller
22
. Thereby, the separation roller
22
is held in a state of being separated from the feeding roller
21
while resisting an operation of the pressing spring
81
.
When the solenoid
95
is turned on, the plunger
96
is pulled in the direction indicated by an arrow E in
FIG. 7
, and the releasing lever
90
is rotated centered around the supporting axis
91
in the clockwise direction indicated by an arrow F while resisting an operation of the releasing spring
92
, so the releasing lever
90
separate from the contact part
85
. Thereby, the pressing lever
80
rotates in the clockwise direction by an operation of the pressing spring
81
, and upwardly moves the separation roller
22
via the upwardly-pressing part
83
, so the separation roller
22
is pressed against and contacts the feeding roller
21
.
As described above, in the above-described contact/separation device, the separation roller
22
is brought into contact with and separated from the feeding roller
21
by turning on/off the solenoid
95
. Therefore, with the above-described contact/separation device at each of the sheet feeding devices
11
-
14
, in each of the sheet feeding devices which are not feeding a sheet, even when the separation roller
22
and the conveying roller
24
are driven, separating the separation roller
22
from the feeding roller
21
avoids an unnecessary load on the separation roller
22
.
Thus, the sheet feeding devices which are not feeding the sheet can be driven by a lower power than that for the sheet feeding device feeding the sheet. Specifically, when the power supplied to the stepping motor
31
of the sheet feeding unit
30
of the sheet feeding device feeding a sheet is set at a maximum phase current of 1.3A, for example, (hereinafter, a high power), the sheet can be satisfactorily conveyed even when the stepping motor
31
of the sheet feeding unit
30
of the sheet feeding devices not feeding the sheet is switched to a maximum phase current of 0.9A, for example, (hereinafter, a low power), which is lower than the high power for the sheet feeding device feeding the sheet.
Turning now to
FIG. 9
, which illustrates a table showing sheet feeding devices driven at low power when each of the sheet feeding devices
11
-
14
is selected. In the table of
FIG. 9
, the sheet feeding device marked with an “H” is the one selected for sheet feeding, and the motor
31
of the sheet feeding unit
30
is driven at the high power. The sheet feeding devices marked with an “L” are not selected for sheet feeding, and the motor
31
is driven at the lower power. The sheet feeding devices marked with an “x” are not driven.
Thus, in the above-described image forming apparatus according to an embodiment of the present invention, the consumption of electricity is reduced as compared to each of the motors
31
of the sheet feeding devices located above the sheet feeding device being driven at the same high power as that for the sheet feeding device selected for sheet feeding. Further, when a lower sheet feeding device of the sheet feeding devices
11
-
14
is selected for sheet feeding, a reduction in the consumption of electricity is greater.
Next,
FIG. 10
is a schematic drawing of an example of the sheet feeding unit
30
according to another preferred embodiment of the present invention.
FIG. 11
is a front view illustrating the sheet feeding devices
11
-
14
, arranged in multiple-stages in a vertical direction, each including the sheet feeding unit
30
of FIG.
10
. In
FIGS. 10 and 11
, the same or corresponding members as in the above-described embodiment are denoted by the same reference numerals. Further, the mechanism connecting the motor
31
with the driving axis
34
of the separation roller
22
is substantially the same as in the previous embodiment. Therefore, the description thereof is omitted.
As shown, a timing pulley
50
having a gear
51
is arranged below the timing pulley
46
having the gear
47
, and the timing belt
49
is spanned around three timing pulleys, for example, the timing pulley
44
, the timing pulley
46
having the gear
47
, and the timing pulley
50
having the gear
51
. A lower relaying gear
52
engages with the gear
51
of the timing pulley
50
. Also, a gear
54
is provided to the roller axis
45
of the conveying roller
24
so as to substantially overlay with the gear
48
. The gear
54
engages with an upper relaying gear
53
.
Further, the lower relaying gear
52
of the sheet feeding unit
30
of the sheet feeding device
11
, for example, engages with the upper relaying gear
53
of the sheet feeding unit
30
of the sheet feeding device
12
arranged below the sheet feeding device
11
as illustrated in FIG.
11
. The gear
54
is also provided to the roller axis
45
of the conveying roller
24
via a one-way clutch
54
a
. When the gear
47
of the timing pulley
46
or the upper relaying gear
53
rotates, the one-way clutch
54
a
transmits each driving force so the conveying roller
24
rotates. However, because the one-way clutch
54
a
does not transmit rotation of the roller axis
45
of the conveying roller
24
to the upper relaying gear
53
and the gear
47
, the upper relaying gear
53
is never rotated by rotation of the conveying roller
24
.
Thus, in each of the sheet feeding devices
11
-
14
illustrated in
FIG. 11
, when the upper relaying gear
53
of the sheet feeding unit
30
of the sheet feeding device
12
, for example, is rotated by receiving a driving force of the lower relaying gear
52
of the sheet feeding unit
30
of the sheet feeding device
11
located immediately above, the conveying roller
24
of the sheet feeding unit
30
of the sheet feeding device
12
rotates. When the gear
48
of the roller axis
45
of the conveying roller
24
rotates, the timing pulley
46
having the gear
47
engaging with the gear
48
rotates, and the timing belt
49
moves in the clockwise direction in FIG.
11
. Accordingly, because the timing pulley
50
having the gear
51
rotates, the lower relaying gear
52
engaging with the gear
51
of the timing pulley
50
rotates. Further, a driving force caused by movement of the timing belt
49
is not transmitted to the driving axis
34
of the separation roller
22
, because as illustrated in
FIG. 10
, a one-way clutch
44
a
is provided to the timing pulley
44
so the movement of the timing belt
49
in the clockwise direction is not transmitted to the driving axis
34
of the separation roller
22
.
Thus, when the lower relaying gear
52
of the feeding unit
30
of the sheet feeding device
11
at the uppermost stage of the multiple stages is rotated, the conveying roller
24
of each feeding unit
30
of the other sheet feeding devices below the upper sheet feeding device
11
can be rotated. Therefore, when the sheet feeding device
14
at the lowermost stage feeds a sheet, the uppermost sheet feeding device
11
and the lowermost sheet feeding device
14
are driven, and without driving the intermediate sheet feeding devices
12
and
13
, the conveying roller
24
of each sheet feeding unit
30
of the intermediate sheet feeding devices
12
and
13
are driven by receiving a driving force of the sheet feeding unit
30
of the uppermost sheet feeding device
11
.
Accordingly, as indicated by a table of
FIG. 12
, because sheet feeding can be performed by only driving the uppermost sheet feeding device
11
and one of the other sheet feeding devices
12
,
13
and
14
selected for sheet feeding, the reduction of power consumption increases as the number of stages of sheet feeding devices increases. Further, the motor
31
of the feeding unit
30
of the uppermost sheet feeding device
11
rotates only in the reverse direction, unless the uppermost sheet feeding device
11
is selected for sheet feeding.
In the above-described embodiment, a driving force of the motor
31
is transmitted to the feeding roller
21
and the separation roller
22
using a belt and gears so the feeding roller
21
and the separation roller
22
are driven to rotate. However, the driving force of the motor
31
can be transmitted to the feeding roller
21
and the separation roller
22
using a series of gears.
FIG. 13
illustrates an exemplary construction of the sheet feeding unit
30
in which a driving force of the motor
31
is transmitted to the feeding roller
21
and the separation roller
23
via a series of gears.
In
FIG. 13
, a gear
60
is provided to the output axis
32
of the motor
31
, and the gear
60
engages with a gear
61
provided to the driving axis
34
of the separation roller
22
via a one-way clutch
61
a
. The gear
61
engages, via an idle gear
62
, with a small-diameter two-step gear
63
b
provided to the driving axis
33
of the feeding roller
21
via a one-way clutch
63
a
. Further, a large-diameter two-step gear
63
c
engages with a gear
40
provided to the driving axis
34
via a one-way clutch
40
a.
In this instance, the one-way clutch
61
a
is configured such that rotation of the gear
61
is transmitted to the driving gear
34
of the separation roller
22
when the gear
61
is rotated with rotation of the motor
31
in the reverse direction, and the rotation of the gear
61
is not transmitted to the driving gear
34
when the motor
31
rotates in the forward direction. Further, the one-way clutch
63
a
is configured such that rotation of the gear
61
is transmitted to the driving axis
33
of the feeding roller
21
when the gear
61
is rotated with rotation of the motor
31
in the forward direction. In addition, the one-way clutch
40
a
is configured such that driving of the gear
40
is transmitted to the driving axis
34
of the separation roller
22
when the gear
40
is driven via the two-step gears
63
b
and
63
c.
In the sheet feeding unit
30
configured as described above, when the motor
31
rotates in the forward direction, a driving force of the motor
31
is transmitted via the gear
61
, the idle gear
62
and the two-step gears
63
b
and
63
c
, so the driving axis
33
of the feeding roller
21
is driven to rotate. Further, the gear
40
engaging with the two-step gears
63
b
and
63
c
is rotated so the driving axis
34
of the separation roller
22
is driven to rotate. When the motor
31
rotates in the reverse direction, the driving axis
34
of the separation roller
22
is driven to rotate by the gear
61
. However, the driving axis
33
of the feeding roller
21
is not driven to rotate, because the one-way clutch
63
a
provided at the two-step gears
63
b
and
63
c
does not transit the driving force of the motor
31
when the motor
31
rotates in the reverse direction.
In the above-described embodiment, substantially the same effect as in the previous embodiments is obtained. Further, in the above-described embodiment, the part of the sheet feeding unit
30
downstream of the driving axis
34
of the separation roller
22
in the direction in which a driving force of the motor
31
is transmitted is substantially the same as that in the previous embodiments, and therefore the description thereof is omitted.
Numerous additional modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the present invention may be practiced otherwise than as specifically described herein.
Claims
- 1. A sheet feeding device, comprising:a sheet tray configured to accommodate stacked sheets; and a sheet feeding unit configured to feed the stacked sheets in the sheet tray one by one, the sheet feeding unit including, a feeding roller configured to be driven to rotate in a sheet feeding direction in which each of the sheets is fed, a separation roller configured to be pressed against the feeding roller when feeding each of the sheets and to be driven to rotate, via a torque limiter, in a direction opposite the sheet feeding direction, the separation roller being rotated by rotation of the feeding roller in the sheet feeding direction when a single sheet of the stacked sheets is sandwiched between the feeding roller and the separation roller, a conveying member arranged downstream from the feeding roller in the sheet feeding direction, a driving source configured to drive the feeding roller, the separation roller, and the conveying member, and a driving force transmission mechanism configured to transmit a driving force of the driving source to each of the feeding roller, the separation roller and the conveying member so the separation roller and the conveying member are driven in conjunction with each other.
- 2. The sheet feeding device of claim 1,wherein the driving source includes a reversible motor configured to be switched between being driven to rotate in first and second directions.
- 3. The sheet feeding device of claim 2,wherein the driving transmission mechanism is configured to transmit the driving force of the motor so the feeding roller, the separation roller, and the conveying member are driven when the driving source is driven to rotate in the first direction, and so the feeding roller is not driven and the separation roller and the conveying member are driven in conjunction with each other when the driving source is driven to rotate in the second direction.
- 4. The sheet feeding device of claim 2,wherein the separation roller and the conveying member are configured to be continuously driven in conjunction with each other by the driving source from when each sheet starts to be fed by the feeding roller until the sheet passes the conveying member.
- 5. The sheet feeding device of claim 2,wherein the driving source is switched from being driven to rotate in the first direction to being driven to rotate in the second direction while the sheet is being sandwiched between the feeding roller and the separation roller.
- 6. The sheet feeding device of claim 2,wherein the driving force transmission mechanism includes driving force transmission members and mechanical one-way clutches.
- 7. The sheet feeding device of claim 6,wherein the driving force transmission mechanism include gears and a belt.
- 8. The sheet feeding device of claim 7,wherein the driving force transmission mechanism transmits the driving force of the driving source to the separation roller via the belt and the gears when the driving source is driven to rotate in the first direction, and the driving force transmission mechanism transmits the driving force of the driving source to the separation roller via the belt when the driving source is driven to rotate in the second direction.
- 9. The sheet feeding device of claim 6,wherein the driving force transmission members include a series of gears.
- 10. The sheet feeding device of claim 9,wherein the driving force transmission mechanism transmits the driving force of the driving source to the separation roller via a first portion of the series of gears when the driving source is driven to rotate in the first direction, and the driving force transmission mechanism transmits the driving force of the driving source to the separation roller via a second portion of the series of gears when the driving source is driven to rotate in the second direction, the first portion of the series of gears being greater in number than the second portion of the series of gears by an odd number.
- 11. The sheet feeding device of claim 2,wherein the driving force transmission mechanism includes a first rotation transmission route configured to transmit the driving force of the driving source when the driving source is driven to rotate in the first direction, and includes a second rotation transmission route configured to transmit the driving force of the driving source when the driving source is driven to rotate in the second direction.
- 12. The sheet feeding device of claim 11,wherein the driving force transmission mechanism includes a belt and gears, and wherein the first rotation transmission route is configured to transmit the driving force of the driving source to the feeding roller via the belt and then from the feeding roller to the reverse roller via the gears, and the second rotation transmission route is configured to transmit the driving force of the driving source to the separation roller via the belt.
- 13. The sheet feeding device of claim 11,wherein the driving force transmission mechanism includes a series of gears, and wherein the first rotation transmission route is configured to transmit the driving force of the driving source to the separation roller via a first portion of the series of gears, and the second rotation transmission route is configured to transmit the driving force of the driving source to the separation roller via a second portion of the series of gears, the first portion of the series of gears being greater in number than the second portion of the series of gears by an odd number.
- 14. The sheet feeding device of claim 1,wherein the feeding unit is detachable from the sheet feeding device.
- 15. An image forming apparatus, comprising:an image forming unit configured to form a toner image on a photoconductor; and a sheet feeding device including a sheet tray configured to accommodate stacked sheets and a sheet feeding unit configured to feed the stacked sheets in the sheet tray one by one toward the image forming unit so the toner image is transferred onto each sheet at the image forming unit, the sheet feeding unit including, a feeding roller configured to be driven to rotate in a sheet feeding direction in which each of the sheets is fed, a separation roller configured to be pressed against the feeding roller when feeding each of the sheets and to be driven to rotate, via a torque limiter, in a direction opposite the sheet feeding direction, the separation roller being rotated by rotation of the feeding roller in the sheet feeding direction when a single sheet of the stacked sheets is sandwiched between the feeding roller and the separation roller, a conveying member arranged downstream from the feeding roller in the sheet feeding direction, a driving source configured to drive the feeding roller, the separation roller, and the conveying member, and a driving force transmission mechanism configured to transmit a driving force of the driving source to each of the feeding roller, the separation roller and the separation member so the separation roller and the conveying member are driven in conjunction with each other.
- 16. The image forming apparatus of claim 15,wherein the driving source of the sheet feeding unit includes a reversible motor configured to be switched between being driven to rotate in first and second directions.
- 17. The image forming apparatus of claim 16,wherein the driving transmission mechanism of the sheet feeding unit is configured to transmit the driving force of the motor so the feeding roller, the separation roller, and the conveying member of the sheet feeding unit are driven when the driving source is driven to rotate in the first direction, and so the feeding roller is not driven and the separation roller and the conveying member are driven in conjunction with each other when the driving source is driven to rotate in the second direction.
- 18. The image forming apparatus of claim 16,wherein the separation roller and the conveying member of the feeding unit are configured to be continuously driven in conjunction with each other by the driving source from when each sheet starts to be fed by the feeding roller until the sheet passes the conveying member.
- 19. The image forming apparatus of claim 16,wherein the driving source is switched from being driven to rotate in the first direction to being driven to rotate in the second direction while the sheet is being sandwiched between the feeding roller and the separation roller.
- 20. The image forming apparatus of claim 16,wherein the driving force transmission mechanism includes driving force transmission members and mechanical one-way clutches.
- 21. The image forming apparatus of claim 20,wherein the driving force transmission members include gears and a belt.
- 22. The image forming apparatus of claim 21,wherein the driving force transmission mechanism transmits the driving force of the driving source to the separation roller via the belt and the gears when the driving source is driven to rotate in the first direction, and the driving force transmission mechanism transmits the driving force of the driving source to the separation roller via the belt when the driving source is driven to rotate in the second direction.
- 23. The image forming apparatus of claim 20,wherein the driving force transmission members includes a series of gears.
- 24. The image forming apparatus of claim 23,wherein the driving force transmission mechanism transmits the driving force of the driving source to the separation roller via a first portion of the series of gears when the driving source is driven to rotate in the first direction, and the driving force transmission mechanism transmits the driving force of the driving source to the separation roller via a second portion of the series of gears when the driving source is driven to rotate in the second direction, the first portion of the series of gears is greater in number than the second portion of the series of gears by an odd number.
- 25. The image forming apparatus of claim 16,wherein the driving force transmission mechanism includes a first rotation transmission route configured to transmit the driving force of the driving source when the driving source is driven to rotate in the first direction, and includes a second rotation transmission route configured to transmit the driving force of the driving source when the driving source is driven to rotate in the second direction.
- 26. The image forming apparatus of claim 25,wherein the driving force transmission mechanism includes a belt and gears, and wherein the first rotation transmission route is configured to transmit the driving force of the driving source to the feeding roller via the belt and then from the feeding roller to the reverse roller via the gears, and the second rotation transmission route is configured to transmit the driving force of the driving source to the separation roller via the belt.
- 27. The image forming apparatus of claim 25,wherein the driving force transmission mechanism includes a series of gears, and wherein the first rotation transmission route is configured to transmit the driving force of the driving source to the separation roller via a first portion of the series of gears, and the second rotation transmission route is configured to transmit the driving force of the driving source to the separation roller via a second portion of the series of gears, the first portion of the series of gears being greater in number than the second portion of the series of gears by an odd number.
- 28. The image forming apparatus of claim 15,wherein the feeding unit is detachable from the sheet feeding device.
- 29. An image forming apparatus, comprising:an image forming unit configured to form a toner image on a photoconductor; and a plurality of sheet feeding devices, each including a sheet tray configured to accommodate stacked sheets and a sheet feeding unit configured to feed the stacked sheets in the sheet tray one by one toward the image forming unit so the toner image is transferred onto each sheet at the image forming unit, each of the plurality sheet feeding unit including, a feeding roller configured to be driven to rotate in a sheet feeding direction in which each of the sheets is fed, a separation roller configured to be pressed against the feeding roller when feeding each of the sheets and to be driven to rotate, via a torque limiter, in a direction opposite the sheet feeding direction, the separation roller being rotated by rotation of the feeding roller in the sheet feeding direction when a single sheet of the stacked sheets is sandwiched between the feeding roller and the separation roller, a conveying member arranged downstream from the feeding roller in the sheet feeding direction, a driving source configured to drive the feeding roller, the separation roller, and the conveying member, and a driving force transmission mechanism configured to transmit a driving force of the driving source to each of the feeding roller, the separation roller and the conveying member so the separation roller and the conveying member are driven in conjunction with each other.
- 30. The image forming apparatus of claim 29,wherein the driving source of each sheet feeding unit of the plurality of sheet feeding devices includes a reversible motor configured to be switched between being driven to rotate in first and second directions.
- 31. The image forming apparatus of claim 30,wherein the driving transmission mechanism of each sheet feeding unit of the plurality of sheet feeding devices is configured to transmit the driving force of the motor so the feeding roller, the separation roller, and the conveying member are driven when the driving source is driven to rotate in the first direction, and so the feeding roller is not driven and the separation roller and the conveying member are driven in conjunction with each other when the driving source is driven to rotate in the second direction.
- 32. The image forming apparatus of claim 30,wherein the separation roller and the conveying member of each sheet feeding unit of the plurality of sheet feeding devices are configured to be continuously driven in conjunction with each other by the driving source from when each sheet starts to be fed by the feeding roller until the sheet passes the conveying roller.
- 33. The image forming apparatus of claim 30,wherein the driving source is switched from being driven to rotate in the first direction to being driven to rotate in the second direction while the sheet is being sandwiched between the feeding roller and the separation roller.
- 34. The image forming apparatus of claim 30,wherein the driving force transmission mechanism of each sheet feeding unit of the plurality of sheet feeding devices includes driving force transmission members and mechanical one-way clutches.
- 35. The image forming apparatus of claim 34,wherein the driving force transmission members include gears and a belt.
- 36. The image forming apparatus of claim 35,wherein the driving force transmission mechanism transmits the driving force of the driving source to the separation roller via the belt and the gears when the driving source is driven to rotate in the first direction, and the driving force transmission mechanism transmits the driving force of the driving source to the separation roller via the belt when the driving source is driven to rotate in the second direction.
- 37. The image forming apparatus of claim 34,wherein the driving force transmission members include a series of gears.
- 38. The image forming apparatus of claim 37,wherein the driving force transmission mechanism transmits the driving force of the driving source to the separation roller via a first portion of the series of gears when the driving source is driven to rotate in the first direction, and the driving force transmission mechanism transmits the driving force of the driving source to the separation roller via a second portion of the series of gears when the driving source is driven to rotate in the second direction, the first portion of the series of gears is greater in number than the second portion of the series of gears by an odd number.
- 39. The image forming apparatus of claim 30,wherein the driving force transmission mechanism includes a first rotation transmission route configured to transmit the driving force of the driving source when the driving source is driven to rotate in the first direction, and includes a second rotation transmission route configured to transmit the driving force of the driving source when the driving source is driven to rotate in the second direction.
- 40. The image forming apparatus of claim 39,wherein the driving force transmission mechanism includes a belt and gears, and wherein the first rotation transmission route is configured to transmit the driving force of the driving source to the feeding roller via the belt and then from the feeding roller to the reverse roller via the gears, and the second rotation transmission route is configured to transmit the driving force of the driving source to the separation roller via the belt.
- 41. The image forming apparatus of claim 39,wherein the driving force transmission mechanism includes a series of gears, and wherein the first rotation transmission route is configured to transmit the driving force of the driving source to the separation roller via a first portion of the series of gears, and the second rotation transmission route is configured to transmit the driving force of the driving source to the separation roller via a second portion of the series of gears, the first portion of the series of gears being greater in number than the second portion of the series of gears by an odd number.
- 42. The image forming apparatus of claim 29,wherein the sheet feeding unit of each of the plurality of sheet feeding devices is detachable from the sheet feeding device.
- 43. The image forming apparatus of claim 30,wherein the plurality of sheet feeding devices are arranged in multiple stages in a vertical direction in parallel with each other, and wherein the sheet feeding units of the plurality of sheet feeding devices are individually driven such that each sheet fed from one of the plurality of sheet feeding devices is fed toward the image forming unit via the conveying member of each of other sheet feeding devices of the plurality of sheet feeding devices located above the sheet feeding device from which the sheet is fed.
- 44. The image forming apparatus of claim 43,wherein the sheet feeding units of any neighboring sheet feeding devices of the plurality of sheet feeding devices are connected with each other so the driving force of the driving source of the sheet feeding unit of the sheet feeding device of the neighboring sheet feeding devices, located at a lower side, is not transmitted to the feeding unit of the sheet feeding device of the neighboring feeding devices, located at an upper side, and the driving force of the driving source of the feeding unit of the sheet feeding device of the neighboring sheet feeding devices, located at the upper side, is transmitted to the sheet feeding unit of the sheet feeding device of the neighboring sheet feeding devices, located at the lower side.
- 45. The image forming apparatus of claim 44,wherein the separation roller and the conveying member of the feeding unit of an uppermost sheet feeding device of the plurality of sheet feeding devices and the separation roller and the conveying member of the feeding unit of the sheet feeding device of the plurality of sheet feeding devices, feeding the sheet, are respectively driven in conjunction with each other, and the separation roller and the conveying member of each of the sheet feeding units of other sheet feeding devices of the plurality of sheet feeding devices, not feeding the sheet, are not driven in conjunction with each other and only the conveying member is driven.
- 46. The image forming apparatus of claim 43,wherein the driving source of the sheet feeding unit of the sheet feeding device of the plurality of sheet feeding devices, feeding the sheet, is driven by a predetermined power, and the driving source of the sheet feeding unit of each of other sheet feeding devices located above the sheet feeding device feeding the sheet is driven at a power smaller than the predetermined power.
- 47. The image forming apparatus of claim 46,wherein the driving source of the sheet feeding unit of each of the other sheet feeding devices located below the sheet feeding device feeding the sheet is not driven.
- 48. The image forming apparatus of claim 46,wherein each of the sheet feeding devices includes a contact/separation device configured to bring the separation roller into contact with the feeding roller and to separate the separation roller from the feeding roller, and wherein the contact/separation device is configured to separate the separation roller from the feeding roller except when the sheet feeding device feeds each of the stacked sheets.
- 49. A sheet feeding device, comprising:means for accommodating stacked sheets; and feeding means for feeding the stacked sheets in the sheet accommodating means one by one, the sheet feeding means including, feeding roller means for rotating in a sheet feeding direction in which each of the stacked sheets is fed, separation roller means for pressing against the feeding roller means when feeding each of the stacked sheets and for rotating in a direction opposite the sheet feeding direction, the separation roller means being rotated by rotation of the feeding roller means in the sheet feeding direction when a single sheet of the stacked sheets is sandwiched between the feeding roller means and the separation roller means, means for conveying the sheet, arranged downstream of the feeding roller means in the sheet feeding direction, means for driving the feeding roller means, the separation roller means, and the conveying means, and means for transmitting a driving force of the driving means to each of the feeding roller means, the separation roller means and the conveying means so the separation roller means and the conveying means are driven in conjunction with each other.
- 50. An image forming apparatus, comprising:means for forming a toner image on a photoconductor; and sheet feeding means for feeding stacked sheets accommodated in a sheet accommodating means one by one toward the image forming means so the toner image is transferred onto each sheet at the image forming means, the sheet feeding means including, feeding roller means for rotating in a sheet feeding direction in which each of the stacked sheets is fed, separation roller means for pressing against the feeding roller means when feeding each of the stacked sheets and for rotating in a direction opposite the sheet feeding direction, the separation roller means being rotated by rotation of the feeding roller means in the sheet feeding direction when a single sheet of the stacked sheets is sandwiched between the feeding roller means and the separation roller means, means for conveying the sheet, arranged downstream of the feeding roller means in the sheet feeding direction, means for driving the feeding roller means, the separation roller means, and the conveying means, and means for transmitting a driving force of the driving means to the feeding roller means, the separation roller means and the conveying means so the separation roller means and the conveying means are driven in conjunction with each other.
- 51. An image forming apparatus, comprising:means for forming a toner image on a photoconductor; and a plurality of sheet feeding means for feeding stacked sheets accommodated in a sheet accommodating means one by one toward the image forming means so the toner image is transferred onto each sheet at the image forming means, the sheet feeding means including, feeding roller means for rotating in a sheet feeding direction in which each of the stacked sheets is fed, separation roller means for pressing against the feeding roller means when feeding each of the stacked sheets and for rotating in a direction opposite the sheet feeding direction, the separation roller means being rotated by rotation of the feeding roller means in the sheet feeding direction when a single sheet of the stacked sheets is sandwiched between the feeding roller means and the separation roller means, means for conveying the sheet, arranged downstream of the feeding roller means in the sheet feeding direction, means for driving the feeding roller means, the separation roller means, and the conveying means, and means for transmitting a driving force of the driving means to each of the feeding roller means, the separation roller means and the conveying means so the separation roller means and the conveying means are driven in conjunction with each other.
- 52. A method of feeding stacked sheets one by one in a sheet feeding device having a feeding roller, a separation roller and a conveying member, comprising:driving a motor to rotate in a first direction and transmitting a driving force of the motor with a driving force transmitting mechanism to the feeding roller, the separation roller and the conveying member so the feeding roller is driven to rotate in a sheet feeding direction, the separation roller is driven to rotate in a direction opposite the sheet feeding direction, and the conveying member is driven to rotate in the sheet feeding direction; and driving the motor to rotate in a second direction and transmitting the driving force of the motor to the feeding roller, the separation roller and the conveying member so the feeding roller is stopped, and the separation roller and the conveying roller are driven to rotate in respective directions in conjunction with each other.
Priority Claims (2)
Number |
Date |
Country |
Kind |
2000-400698 |
Dec 2000 |
JP |
|
2001-366526 |
Nov 2001 |
JP |
|
US Referenced Citations (3)
Number |
Name |
Date |
Kind |
5474287 |
Takahashi |
Dec 1995 |
A |
5755435 |
Fujiwara |
May 1998 |
A |
5975516 |
Maruchi et al. |
Nov 1999 |
A |
Foreign Referenced Citations (2)
Number |
Date |
Country |
6-9079 |
Jan 1994 |
JP |
8-59000 |
Mar 1996 |
JP |