[Technical Field]
[0001] The present invention generally relates to an image forming apparatus and a method
for feeding a sheet from a stack of sheets.
[Background Art]
[0002] Conventional printers comprise a sheet feeding device for picking up and feeding
to a printing unit one sheet from a stack of a plurality of sheets. The sheet feeding
device feeds the top sheet from the stack of the plurality of sheets to the printing
unit by, for example, rotating a roller in contact with the sheet (for example, see
Patent Literature 1).
[Citation List]
[Patent Literature]
[0003] [Patent Literature 1] Japanese Patent Application Publication No.
2013-234060
[0004] In such a sheet feeding device, when feeding of the sheet ends, the roller is retracted
to a retracted position not in contact with the sheet by a driving force that reverses
the roller. At this time, the roller is held in the retracted position by a holding
portion.
[0005] However, if the roller rotates in reverse while the holding portion is holding the
roller, the roller and the holding portion rub together and generate noise.
[Summary of the Invention]
[0006] According to one or more embodiments of the present invention, an image forming apparatus
comprises a sheet feeding device that can reduce noise when holding a roller away
from a stack of a plurality of sheets.
[0007] According to one or more embodiments of the present invention, an image forming apparatus
comprises a driving source configured to rotate a first shaft around the first shaft,
for example both in a first and in a second rotation direction opposite the first
rotation direction, and a feeding mechanism.
[0008] According to one or more embodiments of the present invention, the feeding mechanism
may comprise a transmission mechanism configured to transmit rotation of the first
shaft only in a first direction to the second shaft. In other words, the transmission
mechanism is configured not to transmit rotation of the first shaft in a direction
opposite the first direction to the second shaft.
[0009] According to one or more embodiments of the present invention, the feeding mechanism
may also comprise a roller fixed in a rotatable manner to the second shaft and configured
to feed a sheet from a stack of sheets by rotating around the second shaft.
[0010] According to one or more embodiments of the present invention, the feeding mechanism
may also comprise a releasing member fixed to the second shaft.
[0011] According to one or more embodiments, the image forming apparatus may further comprise
a holding mechanism configured to hold the feeding mechanism with the roller away
from the stack.
[0012] According to one or more embodiments, the releasing member may be configured to release
the feeding mechanism held by the holding mechanism when the transmission mechanism
transmits the rotation of the first shaft to the second shaft.
[0013] Further embodiments of the image forming apparatus are defined in the dependent claims.
[0014] According to one or more embodiments of the present invention, for example, a sheet
feeding device for feeding a sheet from a stack of a plurality of sheets, may comprise:
a driving source configured to rotate a first shaft in both directions; a feeding
mechanism that comprises a roller that is fixed in a rotatable manner to a second
shaft and is configured to feed the sheet by rotating around the second shaft while
contacting the sheet; and a holding mechanism configured to hold the feeding mechanism
with the roller away from the stack of the plurality of sheets; wherein the feeding
mechanism may further comprise an arm that connects the first shaft and the second
shaft, the arm being configured to turn the second shaft around the first shaft by
rotation of the first shaft; a transmission mechanism that is provided in the arm
and is configured to selectively perform transmission and non-transmission of rotation
from the first shaft to the second shaft according to a rotational direction of the
first shaft; and a releasing member that is fixed to the second shaft and is configured
to release the hold on the feeding mechanism by the holding mechanism by rotating
around the second shaft.
[0015] According to this configuration, transmission and non-transmission of rotation from
the first shaft to the second shaft can be performed selectively according to a rotational
direction of the first shaft. Therefore, reverse rotation of the roller can be prevented,
and noise due to the roller and the holding mechanism rubbing together can be reduced.
Moreover, by the releasing member rotating around the second shaft, the hold on the
feeding mechanism by the holding mechanism can be released. That is, when rotation
is transmitted from the first shaft to the second shaft, the hold on the feeding mechanism
by the holding mechanism can be released, and the second shaft can be turned around
the first shaft in a direction approaching the stack of the sheets. Moreover, when
rotation is not transmitted from the first shaft to the second shaft, the hold on
the feeding mechanism by the holding mechanism can be maintained. Therefore, it becomes
possible to stably hold the feeding mechanism with the roller away from the stack
of the plurality of sheets when not feeding the sheet.
[0016] According to one or more embodiments of the present invention, for example, the holding
mechanism may comprise a holding portion configured to hold the arm.
[0017] According to this configuration, the holding portion can hold the arm. The arm has
less rattling than the roller and also has high freedom in design for the held portion.
Therefore, the feeding mechanism can be held more stably than holding the roller.
[0018] According to one or more embodiments of the present invention, for example, the holding
mechanism may further comprise an elastic portion configured to press the holding
portion to the arm, and the releasing member may be configured to release the hold
on the arm by the holding portion by pressing the holding portion in a direction away
from the arm.
[0019] According to this configuration, the releasing member can release the hold on the
arm by the holding portion by pressing the holding portion pressed to the arm by the
elastic portion in the direction away from the arm. Therefore, the releasing member
can be realized by a relatively simple configuration.
[0020] According to one or more embodiments of the present invention, for example, an engaging
portion configured to engage with the holding portion may be formed on a tip portion
of the arm, and the releasing member may be configured to release the engagement between
the engaging portion and the holding portion.
[0021] According to one or more embodiments of the present invention, the holding portion
can engage with the engaging portion formed on the tip portion of the arm. Therefore,
the holding portion can stably hold the arm.
[0022] According to one or more embodiments of the present invention, for example, the transmission
mechanism may be further comprise a plurality of gears, comprising a first gear rotatable
around the first shaft and a second gear rotatable around the second shaft; and a
clutch that is installed between at least one gear from among the plurality of gears
and the rotational shaft of the at least one gear and is configured to transmit transmission
and non-transmission of rotation between the at least one gear and the rotational
shaft according to a rotational direction of the at least one gear.
[0023] According to this configuration, transmission and non-transmission of rotation between
a gear and a rotational shaft can be switched according to a rotational direction
of the gear by the clutch installed between the gear and the rotational shaft. That
is, transmission and non-transmission of rotation from the first shaft to the second
shaft can be switched by the clutch according to a rotational direction of the first
shaft.
[0024] According to one or more embodiments of the present invention, for example, the at
least one gear may be the second gear, the clutch may be configured to switch transmission
and non-transmission of rotation from the second gear to the second shaft according
to a rotational direction of the second gear, and the releasing member may be a cam
formed integrally with the second gear.
[0025] According to this configuration, the clutch can be installed between the second gear
and the second shaft, and the releasing member can be realized as the cam formed integrally
with the second gear. Therefore, a component count can be reduced, and an assembly
operation of the sheet feeding device can be made more efficient.
[0026] According to one or more embodiments of the present invention, for example, the transmission
mechanism may comprise a gear rotatable around the second shaft, and the releasing
member may be a cam formed integrally with the gear.
[0027] According to this configuration, the releasing member can be realized as the can
formed integrally with the gear. Therefore, the component count can be reduced, and
the assembly operation of the sheet feeding device can be made more efficient.
[0028] A printer according to one or more embodiments of the present invention may comprise
the above sheet feeding device.
[0029] According to this configuration, effects similar to those of the above sheet feeding
device can be obtained in the printer.
[0030] According to one or more embodiments of the present invention, an image forming apparatus,
such as for example a printer or any other apparatus having a printing function, may
comprise a feeding mechanism that comprises: a transmission mechanism configured to
transmit rotation of a first shaft in a first direction to a second shaft and does
not transmit rotation of the first shaft in a direction opposite the first direction
to the second shaft; a roller that is fixed in a rotatable manner to the second shaft
and feeds a sheet from a stack of sheets by rotating around the second shaft; and
a releasing member that is fixed to the second shaft; and a holding mechanism configured
to hold the feeding mechanism with the roller away from the stack, wherein when the
transmission mechanism transmits the rotation of the first shaft to the second shaft,
the releasing member is configured to release the hold on the feeding mechanism by
the holding mechanism.
[0031] According to one or more embodiments of the present invention, a method for feeding
a sheet from a stack of sheets may be as defined in claim 11.
[0032] Embodiments of the method are defined in the dependent claims.
[0033] According to one or more embodiments of the present invention, a method for feeding
a sheet from a stack of sheets may comprise rotating a first shaft around the first
shaft, transmitting, with a transmission mechanism, rotation of the first shaft in
a first direction to a second shaft and does not transmit rotation of the first shaft
in a direction opposite the first direction to the second shaft; feeding, with a roller,
the sheet from a stack of sheets by rotating around the second shaft; connecting,
with an arm, the first shaft and the second shaft; holding, with a holding portion,
the arm or the roller with the roller away from the stack; and when the transmitting
transmits the rotation of the first shaft to the second shaft, releasing, with the
releasing member, the hold on the arm or the roller by the holding portion.
[0034] According to one or more embodiments, the holding comprises pressing, with an elastic
portion, the holding portion to the arm, and the releasing presses the holding portion
in a direction away from the arm and releases to hold the arm by the holding portion.
[0035] According to one or more embodiments, an engaging portion that engages with the holding
portion is formed on a tip portion of the arm, and the releasing releases the engagement
between the engaging portion and the holding portion.
[0036] According to one or more embodiments, the transmission mechanism further comprises
a plurality of gears that includes a first gear that rotates around the first shaft
and a second gear that rotates around the second shaft, and a clutch that is installed
between at least one gear from among the plurality of gears and the rotational shaft
of the at least one gear, wherein the transmitting comprises switching, with the clutch,
transmission and non-transmission of rotation between the at least one gear and the
rotational shaft based on a rotational direction of the at least one gear.
[0037] The image forming apparatus and the method for feeding a stack of sheets according
to one or more embodiments of the present invention can reduce noise when holding
the roller away from the stack of the plurality of sheets.
[Brief Description of the Drawings]
[0038]
FIG. 1 is a perspective view illustrating a printer according to one or more embodiments
of the present invention.
FIG. 2 is a cross-sectional view illustrating the printer according to one or more
embodiments of the present invention.
FIG. 3 is a perspective view illustrating a sheet feeding device of the printer according
to one or more embodiments of the present invention.
FIG. 4 is a view from above of the sheet feeding device of the printer according to
one or more embodiments of the present invention.
FIG. 5 is a cross-sectional view illustrating a feeding mechanism of the printer according
to one or more embodiments of the present invention.
FIG. 6 is a view illustrating the feeding mechanism of the sheet feeding device of
the printer according to one or more embodiments of the present invention being held
by a holding mechanism.
FIG. 7 is a view illustrating an operation by which the hold on the feeding mechanism
is released in the sheet feeding device according to one or more embodiments of the
present invention.
FIG. 8 is a view illustrating the sheet feeding device of the printer according to
one or more embodiments of the present invention feeding a sheet.
FIG. 9 is a cross-sectional view illustrating a feeding mechanism of a sheet feeding
device of a printer according to one or more embodiments of a first modified example
of the present invention.
FIG. 10 is a view from above of the sheet feeding device of the printer according
to one or more embodiments of the first modified example of the present invention.
FIG. 11 is a view from above of a sheet feeding device of a printer according to one
or more embodiments of a second modified example of the present invention.
[Detailed Description of Embodiments]
[0039] Embodiments of the present invention will be described below in detail with reference
to the drawings.
[0040] Numerous specific details are set forth herein to provide a more thorough understanding
of the invention. However, it will be apparent to one of ordinary skill in the art
that the invention may be practiced without these specific details. In other instances,
well-known features have not been described in detail.
[0041] A sheet feeding device according to embodiments of the present invention will be
described below with reference to the drawings. In one or more embodiments of the
present invention, the sheet feeding device is included in an image forming apparatus,
such as for example a printer or an MFP (Multi-Function Peripheral) including a printing
function. In the drawings, an x-axis is an axis direction of a roller 111 of the printer;
a y-axis is a direction that crosses the x-axis and a direction to which a recording
medium is transported; and a z-axis is a direction that crosses the x-axis and the
y-axis.
(Configuration of Printer)
[0042] First, a configuration of a printer 10 in accordance with one or more embodiments
comprising a sheet feeding device 100 will be described. FIG. 1 is a perspective view
of the printer 10 according to one or more embodiments of the present invention. FIG.
2 is a cross-sectional view illustrating the printer 10 according to one or more embodiments
of the present invention.
[0043] In one or more embodiments of the present invention, the printer 10 may be a laser
printer. The printer 10 may comprise a chassis 11, a cassette 12, a tray 13, a printing
unit 14, and the sheet feeding device 100.
[0044] The cassette 12 is provided in a lower portion of the chassis 11 and is housed in
the chassis 11 so as to be able to be pulled out in a y-axis direction. The cassette
12 houses a stack 50 of a plurality of sheets.
[0045] A sheet is a thinly-spread medium. For example, the sheet is made from paper, resin,
cloth, or the like.
[0046] The tray 13 is provided on an upper surface of the chassis 11. A printed sheet is
discharged onto the tray 13.
[0047] The printing unit 14 prints an image on the sheet. Specifically, the printing unit
14 comprises, for example, a photoreceptor drum, a transfer roller, a fixing roller,
and the like. A toner image formed on the photoreceptor drum is transferred by the
transfer roller onto a sheet conveyed along a first route 15. Then, the toner image
transferred onto the sheet is fixed on the sheet by the fixing roller.
[0048] The printer 10 according to one or more embodiments of the present invention can
print on both sides of the sheet. When performing double-sided printing, a sheet printed
on one side, after being conveyed to the tray 13 along the first route 15, has its
traveling direction reversed and is conveyed to the cassette 12 along a second route
16. The sheet printed on one side conveyed to the cassette 12 is again fed to the
printing unit 14 along the first route 15 to realize double-sided printing.
[0049] The sheet feeding device 100 feeds one sheet from the stack 50 of the plurality of
sheets. Specifically, the sheet feeding device 100 feeds to the first route 15 one
sheet from the stack 50 of the plurality of sheets housed in the cassette 12.
(Configuration of Sheet Feeding Device)
[0050] Next, a configuration of the sheet feeding device 100 in accordance with one or more
embodiments will be described. FIG. 3 is a perspective view illustrating the configuration
of the sheet feeding device 100 according to one or more embodiments of the present
invention. FIG. 4 is a view from above of the sheet feeding device 100 according to
one or more embodiments of the present invention. FIG. 5 is a cross-sectional view
of a feeding mechanism 110 according to one or more embodiments of the present invention.
[0051] As illustrated in FIG. 3, the sheet feeding device 100 may comprise a driving source
101, the feeding mechanism 110, and a holding mechanism 120. Moreover, the sheet feeding
device 100 may comprise a first shaft 102, a second shaft 103, and a torsion spring
104.
[0052] The driving source 101 is, for example, an electric motor. The driving source 101
rotates the first shaft 102 in both directions. Specifically, in FIG. 3, the driving
source 101 rotates the first shaft 102 in a first direction R1 illustrated by the
solid arrow and a second direction R2 illustrated by the dashed arrow. The second
direction R2 is a direction opposite the first direction R1.
[0053] Furthermore, the driving source 101 rotates in both directions a conveying roller
(not illustrated) that conveys the sheet along the first route 15. That is, the driving
source 101 is used in both feeding of the sheet by the feeding mechanism 110 and conveying
of the sheet along the first route 15.
[0054] The feeding mechanism 110 is a mechanism for feeding one sheet from the stack 50
of the plurality of sheets. The feeding mechanism 110 may comprise a roller 111, an
arm 112, a transmission mechanism 113, and a releasing member 119.
[0055] The roller 111 is also referred to as a pickup roller. The roller 111 is fixed in
a rotatable manner on both ends of the second shaft 103, which is parallel to the
first shaft 102, and rotates around the second shaft 103. The second shaft 103 may
be substantially parallel to the first shaft 102.
[0056] The roller 111 feeds the sheet by rotating around the second shaft 103 while contacting
the sheet. Specifically, the roller 111, for example, by rotating while contacting
the top sheet of the stack 50 of the plurality of sheets, separates the top sheet
from the other sheets and feeds this sheet to the first route 15.
[0057] The arm 112 is a member connecting the first shaft 102 and the second shaft 103.
The arm 112 turns the second shaft 103 around the first shaft 102 by rotation of the
first shaft 102. That is, the arm 112 rotates around the first shaft 102 by rotation
of the first shaft 102. As a result, the second shaft 103 and the roller 111 fixed
to the second axis 103 turn around the first shaft 102.
[0058] "Turn" means to rotate so as to draw a circle around a rotational axis. That is,
"turn" means an object in a position away from a rotational axis rotates around the
rotational axis.
[0059] When the first shaft 102 rotates in the first direction R1, the second shaft 103
and the roller 111 turn in a direction approaching the sheet. Conversely, when the
first shaft 102 rotates in the second direction R2, the second shaft 103 and the roller
111 turn in a direction away from the stack 50 of the plurality of sheets.
[0060] On a tip portion of the arm 112, a first engaging portion 112a that engages with
a holding portion 121 of the holding mechanism 120 is formed. In one or more embodiments
of the present invention, the first engaging portion 112a is a convex portion formed
on an end portion on a second-shaft 103 side of the arm 112. By this first engaging
portion 112a and the holding portion 121 engaging, rotation of the arm 112 around
the first shaft 102 is regulated.
[0061] The transmission mechanism 113 is provided in the arm 112. The transmission mechanism
113 selectively performs transmission and non-transmission of rotation from the first
shaft 102 to the second shaft 103 according to a rotational direction of the first
shaft 102.
[0062] Specifically, the transmission mechanism 113 transmits rotation of the first shaft
102 in the first direction R1 to the second shaft 103 and does not transmit rotation
of the first shaft 102 in the second direction R2 to the second shaft 103. In other
words, the transmission mechanism 113 transmits to the second shaft 103 only rotation
in the first direction R1 from among rotations in the first direction R1 and in the
second direction R2 of the first shaft 102.
[0063] The first direction R1 is a rotational direction of the first shaft 102 for turning
the second shaft 103 and the roller 111 in a direction approaching the stack 50 of
the plurality of sheets. That is, the first direction R1 is a rotational direction
for feeding the sheet. Conversely, the second direction R2 is a rotational direction
of the first shaft 102 for turning the second shaft 103 and the roller 111 in the
direction away from the stack 50 of the plurality of sheets.
[0064] As illustrated in FIG. 5, the transmission mechanism 113 may comprise a first gear
114, a second gear 115, a third gear 116, a fourth gear 117, and a clutch 118.
[0065] The first gear 114 is fixed in a rotatable manner to the first shaft 102 and rotates
around the first shaft 102. The first gear 114 engages with the second gear 115. Here,
the first gear 114 is a spur gear.
[0066] The second gear 115 engages with the first gear 114 and the third gear 116. That
is, the second gear 115 transmits rotation from the first gear 114 to the third gear
116. Here, the second gear 115 is a spur gear.
[0067] Furthermore, on a side surface of the second gear 115, pressure is added by an elastic
member (for example, a coil or a spring) that is not illustrated. By this, a load
is applied to rotation of the second gear 115, and the arm 112 rotates around the
first shaft 102.
[0068] The third gear 116 engages with the second gear 115 and the fourth gear 117. That
is, the third gear 116 transmits rotation from the second gear 115 to the fourth gear
117. Here, the third gear 116 is a spur gear.
[0069] The fourth gear 117 engages with the third gear 116 and rotates around the second
shaft 103. Here, the fourth gear 117 is a spur gear.
[0070] The clutch 118 is a so-called one-way clutch (also referred to as a one-way freewheel
clutch). The clutch 118 is installed between the fourth gear 117 and the second shaft
103.
[0071] The clutch 118 switches transmission and non-transmission of rotation between the
fourth gear 117 and the second shaft 103 according to a rotational direction of the
fourth gear 117. That is, the clutch 118 switches transmission and non-transmission
of rotation from the fourth gear 117 to the second shaft 103 according to the rotational
direction of the fourth gear 117.
[0072] Specifically, when the first shaft 102 is rotating in the first direction R1, the
clutch 118 transmits rotation from the fourth gear 117 to the second shaft 103. Meanwhile,
when the first shaft 102 is rotating in the second direction R2, the clutch 118 does
not transmit rotation from the fourth gear 117 to the second shaft 103.
[0073] The releasing member 119 is fixed to the second shaft 103. The releasing member 119
releases a hold on the feeding mechanism 110 by the holding mechanism 120 by rotating
around the second shaft 103. Specifically, the releasing member 119 releases the engagement
between the first engaging portion 112a of the arm 112 and the holding portion 121.
[0074] In one or more embodiments of the present invention, the releasing member 119 releases
the hold on the feeding mechanism 110 by the holding mechanism 120 by contacting the
holding mechanism 120. Specifically, the releasing member 119 releases a hold on the
arm 112 by the holding portion 121 by pressing the holding portion 121 of the holding
mechanism 120 in a direction away from the arm 112. For example, the releasing member
119 converts rotational movement of the second shaft 103 into linear movement for
pressing the holding portion 121.
[0075] Specifically, the releasing member 119 may be, for example, a cam formed integrally
with the fourth gear 117. More specifically, the releasing member 119 may be, for
example, a plate-shaped cam whose distance from a rotational center (that is, a center
of the second shaft 103) to a circumference is not constant. The releasing member
119 does not have to be formed integrally with the fourth gear 117.
[0076] The holding mechanism 120 holds the feeding mechanism 110 with the roller 111 away
from the stack 50 of the plurality of sheets. That is, the holding mechanism 120 regulates
rotation of the arm 112 around the first shaft 102 and turning of the second shaft
103 and the roller 111 around the first shaft 102. In one or more embodiments of the
present invention, the holding mechanism 120 may comprise the holding portion 121
and an elastic portion 122.
[0077] The holding portion 121 holds the arm 112. A second engaging portion 121a that engages
with the first engaging portion 112a of the arm 112 is formed on the holding portion
121. Here, the second engaging portion 121 a is a concave portion corresponding to
the convex portion that is the first engaging portion 112a.
[0078] The elastic portion 122 is, for example, a coil spring. The elastic portion 122 presses
the holding portion 121 to the arm 112. That is, the elastic portion 122 presses the
holding portion 121 to the arm 112 so the engagement between the first engaging portion
112a of the arm 112 and the second engaging portion 121 a of the holding portion 121
is not released.
[0079] That is, the holding portion 121 is provided in a retractable manner relative to
the arm 112 and is biased toward the arm 112 by the elastic portion 122. Moreover,
the holding portion 121 moves in the direction away from the arm 112 by being pressed
by the releasing member 119. As a result, the hold on the arm 112 by the holding portion
121 is released.
[Operation of Sheet Feeding Device]
[0080] Next, an operation of the sheet feeding device 100 configured as above in accordance
with one or more embodiments will be described. FIG. 6 is a view illustrating the
feeding mechanism 110 of the sheet feeding device 100 according to one or more embodiments
of the present invention being held by the holding mechanism 120. FIG. 7 is a view
illustrating an operation by which the hold on the feeding mechanism 110 is released
in the sheet feeding device 100 according to one or more embodiments of the present
invention. FIG. 8 is a view illustrating the sheet feeding device 100 according to
one or more embodiments of the present invention feeding a sheet. In FIG. 7, the arrows
illustrate rotational direction of each mechanical component when the first shaft
102 rotates in the first direction R1.
[0081] In FIG. 6, the feeding mechanism 110 is held by the holding mechanism 120 with the
roller 111 away from the stack 50 of the plurality of sheets housed in the cassette
12. This position of the feeding mechanism 110 is referred to as a retracted position.
[0082] With the feeding mechanism 110 held in the retracted position in this manner, when
the first shaft 102 rotates in the first direction R1, as illustrated in (a) of FIG.
7, the third gear 116 rotates in the direction of the arrow. As a result, the releasing
member 119 and the roller 111 also rotate in the direction of the arrows together
with the second shaft 103.
[0083] As a result of the releasing member 119 having rotated, as illustrated in (b) of
FIG. 7, the holding portion 121 is pressed by the releasing member 119, and the first
engaging portion 112a and the second engaging portion 121 a separate. That is, the
engagement between the holding portion 121 and the first engaging portion 112a is
released.
[0084] When the engagement between the holding portion 121 and the first engaging portion
112a is released, the arm 112 rotates around the first shaft 102 in the first direction
R1. That is, the second shaft 103 and the roller 111 turn around the first shaft 102
in the first direction R1. As a result, the feeding mechanism 110 moves to the position
illustrated in FIG. 8. This position of the feeding mechanism 110 is referred to as
a feeding position.
[0085] That is, the feeding mechanism 110 moves to the feeding position illustrated in FIG.
8 from the retracted position illustrated in FIG. 6. In the feeding position, the
roller 111, by rotating while contacting the sheet, feeds one sheet from the stack
50 of the plurality of sheets to the first route 15.
[0086] The torsion spring 104 applies a force in a direction that rotates the arm 112 in
the second direction R2 for adjusting a force with which the roller 111 is pressed
to the sheet. However, the torsion spring 104 only applies a force to an extent that
cancels a deadweight of the feeding mechanism 110 in the feeding position. That is,
with the torsion spring 104 alone, the feeding mechanism 110 cannot be held stably
in the retracted position.
[0087] When feeding of the sheet ends, the first shaft 102 rotates in the second direction
R2. Then, the arm 112 rotates around the first shaft 102 in the second direction R2.
That is, the second shaft 103 and the roller 111 turn around the first shaft 102 in
the second direction R2. As a result, the feeding mechanism 110 returns to the retracted
position and is held by the holding mechanism 120.
[0088] When the first shaft 102 is rotating in the second direction R2, rotation is not
transmitted from the fourth gear 117 to the second shaft 103 by the clutch 118. That
is, the releasing member 119 does not rotate. Therefore, the hold on the arm 112 by
the holding portion 121 is maintained.
(Effects)
[0089] As above, according to the sheet feeding device 100 according to one or more embodiments
of the present invention, transmission and non-transmission of rotation from the first
shaft 102 to the second shaft 103 can be performed selectively according to a rotational
direction of the first shaft 102. Therefore, reverse rotation of the roller 111 can
be prevented, and noise due to the roller 111 and the holding mechanism 120 rubbing
together can be reduced. Moreover, by the releasing member 119 rotating around the
second shaft 103, the hold on the feeding mechanism 110 by the holding mechanism 120
can be released. That is, when rotation is transmitted from the first shaft 102 to
the second shaft 103, the hold on the feeding mechanism 110 by the holding mechanism
120 can be released, and the second shaft 103 can be turned around the first shaft
102 in the direction approaching the stack 50 of the sheets. Moreover, when rotation
is not transmitted from the first shaft 102 to the second shaft 103, the hold on the
feeding mechanism 110 by the holding mechanism 120 can be maintained. Therefore, it
becomes possible to stably hold the feeding mechanism 110 with the roller 111 away
from the stack 50 of the plurality of sheets when not feeding the sheet.
[0090] Furthermore, according to the sheet feeding device 100 according to one or more embodiments
of the present invention, the holding portion 121 can hold the arm 112. The arm 112
has less rattling than the roller 111 and also has high freedom in design for the
held portion. Therefore, the feeding mechanism 110 can be held more stably than holding
the roller 111.
[0091] Furthermore, according to the sheet feeding device 100 according to one or more embodiments
of the present invention, the releasing member 119 can release the hold on the arm
112 by the holding portion 121 by pressing in the direction away from the arm 112
the holding portion 121 pressed to the arm 112 by the elastic portion. Therefore,
the releasing member 119 can be realized by a relatively simple configuration.
[0092] Furthermore, according to the sheet feeding device 100 according to one or more embodiments
of the present invention, the holding portion 121 can engage with the engaging portion
formed on the tip portion of the arm 112. Therefore, the holding portion 121 can stably
hold the arm 112.
[0093] Furthermore, according to the sheet feeding device 100 according to one or more embodiments
of the present invention, transmission and non-transmission of rotation between a
gear and a rotational shaft can be switched according to a rotational direction of
the gear by the clutch installed between the gear and the rotational shaft. That is,
transmission and non-transmission of rotation from the first shaft 102 to the second
shaft 103 can be switched by the clutch according to a rotational direction of the
first shaft 102.
[0094] Furthermore, according to the sheet feeding device 100 according to one or more embodiments
of the present invention, the clutch can be installed between the fourth gear 117
and the second shaft 103, and the releasing member 119 can be realized as the cam
formed integrally with the fourth gear 117. Therefore, a component count can be reduced,
and an assembly operation of the sheet feeding device 100 can be made more efficient.
(First Modified Example)
[0095] Embodiments of a first modified example of the present invention will be described
below. Embodiments of the first modified example differ from the above embodiments
of the present invention in that a clutch is installed to a third gear. A sheet feeding
device according to the present modified example will be described below around the
point by which it differs from the above embodiments.
[0096] FIG. 9 is a cross-sectional view illustrating an interior structure of a feeding
mechanism 210 according to one or more embodiments of the first modified example of
the present invention. FIG. 10 is a view from above of the sheet feeding device according
to one or more embodiments of the first modified example of the present invention.
In FIG. 10, so that the gears in the arm 112 can be viewed, the feeding mechanism
210 is displayed with a portion of the arm 112 cut out. Moreover, in FIG. 9 and FIG.
10, components identical or analogous to those in FIG. 5 and FIG. 4 will be labeled
with the same reference signs, and description thereof will be omitted as appropriate.
[0097] The feeding mechanism 210 may comprise the roller 111, the arm 112, a transmission
mechanism 213, and the releasing member 119. The transmission mechanism 213 may comprise
the first gear 114, the second gear 115, a third gear 216a, a fourth gear 216b, a
third shaft 216c, a fifth gear 217, and a clutch 218.
[0098] The third gear 216a engages with the second gear 115. The third gear 216a rotates
around the third shaft 216c.
[0099] The clutch 218 is a one-way clutch similar to the clutch 118 in the above embodiments.
The clutch 218 is installed between the third gear 216a and the third shaft 216c.
[0100] The clutch 218 switches transmission and non-transmission of rotation from the third
gear 216a to the third shaft 216c according to a rotational direction of the third
gear 216a. Specifically, when the first shaft 102 is rotating in the first direction
R1, the clutch 218 transmits rotation from the third gear 216a to the third shaft
216c. Meanwhile, when the first shaft 102 is rotating in the second direction R2,
the clutch 218 does not transmit rotation from the third gear 216a to the third shaft
216c.
[0101] The fourth gear 216b is fixed in a rotatable manner to the third shaft 216c and rotates
around the third shaft 216c. Moreover, the fourth gear 216b engages with the fifth
gear 217.
[0102] The fifth gear 217 is fixed in a rotatable manner to the second shaft 103 and rotates
around the second shaft 103. Moreover, the fifth gear 217 engages with the fourth
gear 216b.
[0103] By the transmission mechanism 213 being configured as above, rotation is transmitted
from the first shaft 102 to the second shaft 103 when the first shaft 102 is rotating
in the first direction R1, and rotation is not transmitted from the first shaft 102
to the second shaft 103 when the first shaft 102 is rotating in the second direction
R2.
[0104] As above, according to the sheet feeding device according to one or more embodiments
of the first modified example of the present invention, effects similar to those of
embodiments of the present invention can be obtained even when the clutch 218 is installed
between the third gear 216a and the third shaft 216c.
(Second Modified Example)
[0105] Embodiments of a second modified example of the invention will be described below.
The present modified example differs from the above embodiments in that a holding
mechanism holds the roller. A sheet feeding device according to the present modified
example will be described below around the point by which it differs from the above
embodiments.
[0106] FIG. 11 is a view from above of the sheet feeding device according to one or more
embodiments of a second modified example of the present invention. In FIG. 11, components
identical or analogous to those in FIG. 4 will be labeled with the same reference
signs, and description thereof will be omitted as appropriate.
[0107] A holding mechanism 320 holds the feeding mechanism 110 with the roller 111 away
from the stack 50 of the plurality of sheets. The holding mechanism 320 may comprise
a holding portion 321 and an elastic portion 322.
[0108] The holding portion 321 holds the roller 111. A contact portion 321a extending toward
the releasing member 119 is formed on the holding portion 321. The releasing member
119 releases the hold on the roller 111 by the holding portion 321 by contacting the
contact portion 321 a.
[0109] The elastic portion 322 presses the holding portion 121 to the roller 111. That is,
the elastic portion 322 presses the holding portion 121 to the roller 111 so the hold
on the roller 111 by the holding portion 321 is not released.
[0110] As above, according to the sheet feeding device according to one or more embodiments
of the second modified example, even when the holding portion 321 holds the roller
111, reverse rotation of the roller 111 can be prevented by the clutch 118, and noise
due to the roller 111 and the holding mechanism 320 rubbing together can be reduced.
Moreover, by the releasing member 119 rotating around the second shaft 103, the hold
on the feeding mechanism 110 by the holding mechanism 320 can be released; therefore,
it becomes possible to stably hold the feeding mechanism 110 with the roller 111 away
from the stack 50 of the plurality of sheets.
(Another Modified Example)
[0111] The sheet feeding devices according to one or more embodiments of the present invention
and the modified examples are described above, but the present invention is not limited
to these embodiments or these modified examples. Various modifications of these embodiments
or modified examples and various combinations of components described in these embodiments
or examples are also possible.
[0112] For example, in the above embodiments and modified examples, the sheet feeding device
is included in a laser printer, but the present invention is not limited thereto.
The sheet feeding device may be included in, for example, an inkjet printer. Moreover,
for example, the sheet feeding device may be included in a copying machine, a facsimile
machine, or a multifunction machine.
[0113] The present invention is also not limited to the configurations of the transmission
mechanism as described in the above embodiments and modified examples. For example,
the transmission mechanism may transmit power using pulleys and belts. Moreover, the
transmission mechanism may transmit power using gears different from spur gears (for
example, bevel gears, helical gears, or the like).
[0114] In the above embodiments and modified examples, the first engaging portion and the
second engaging portion are formed, but shapes of the first engaging portion and the
second engaging portion are not limited to those in the above embodiments and modified
examples. For example, the first engaging portion may be a concave portion, and the
second engaging portion may be a convex portion. That is, as long as the first engaging
portion and the second engaging portion engage, the shapes of the first engaging portion
and the second engaging portion may be any shape.
[0115] Furthermore, the first engaging portion and the second engaging portion do not need
to be provided. For example, the feeding mechanism may be held in the retracted position
by the holding portion supporting the arm from below.
[0116] While in the above embodiments and modified examples the releasing member is a plate-shaped
member having a distance from the rotational center to the circumference which is
not constant, the shape of the releasing member is not limited thereto. For example,
the releasing member may be a rod member extending from the second shaft in a direction
intersecting a shaft direction. In this situation, the hold on the feeding mechanism
by the holding portion is released by the rod member contacting the holding portion.
[0117] A placement of the clutch is not limited to those in the above embodiments and Modified
Example 1. For example, the clutch may be installed between the first shaft and the
first gear.
[0118] Although the disclosure has been described with respect to only a limited number
of embodiments, those skilled in the art, having benefit of this disclosure, will
appreciate that various other embodiments may be devised within the scope of the present
invention.
[Explanation of Reference signs]
[0119]
10 Printer
11 Chassis
12 Cassette
13 Tray
14 Printing unit
15 First route
16 Second route
50 Stack of plurality of sheets
100 Sheet feeding device
101 Driving source
102 First shaft
103 Second shaft
104 Torsion spring
110, 210 Feeding mechanism
111 Roller
112 Arm
112a First engaging portion
113,213 Transmission mechanism
114 First gear
115 Second gear
116, 216a Third gear
117, 216b Fourth gear
118, 218 Clutch
119 Releasing member
120, 320 Holding mechanism
121,321 Holding portion
121a Second engaging portion
122, 322 Elastic portion
216c Third shaft
217 Fifth gear
321 a Contact portion
1. An image forming apparatus (10) comprising:
a driving source (101) configured to rotate a first shaft (102) around the first shaft
(102);
a feeding mechanism (110) comprising:
a transmission mechanism (113) that is configured to transmit rotation of the first
shaft (102) in a first direction (R1) to a second shaft (103) and not to transmit
rotation of the first shaft (102) in a direction (R2) opposite the first direction
(R1) to the second shaft (103);
a roller (111) fixed in a rotatable manner to the second shaft (103) and configured
to feed a sheet from a stack (50) of sheets by rotating around the second shaft (103);
and
a releasing member (119) fixed to the second shaft (103); and
a holding mechanism (120) configured to hold the feeding mechanism (110) with the
roller (111) away from the stack (50), wherein
the releasing member (119) is configured to release the hold on the feeding mechanism
(110) by the holding mechanism (120) when the transmission mechanism (113) transmits
the rotation of the first shaft (102) to the second shaft (103).
2. The image forming apparatus (10) according to claim 1, wherein the feeding mechanism
(110) comprises an arm (112) connecting the first shaft (102) and the second shaft
(103).
3. The image forming apparatus (10) according to claim 2, wherein the arm (112) is configured
to turn the second shaft (103) around the first shaft (102) in a direction toward
the stack (50) when the first shaft (102) rotates.
4. The image forming apparatus (10) according to claim 2 or claim 3, wherein the holding
mechanism (120) is configured to hold the arm (112) or the roller (111).
5. The image forming apparatus (10) according to any of claims 2-4, wherein the holding
mechanism (120) comprises a holding portion (121) that holds the arm (112).
6. The image forming apparatus (10) according to claim 5, wherein
the holding mechanism (120) further comprises an elastic portion (122) configured
to press the holding portion (121) to the arm (112), and
the releasing member (119) is configured to press the holding portion (121) in a direction
away from the arm (112) and to release the arm (112) held by the holding portion (121).
7. The image forming apparatus (10) according to claim 6, wherein
the feeding mechanism (110) further comprises an engaging portion (112a) configured
to engage with the holding portion (121) and formed on a tip portion of the arm (112),
and
the releasing member (119) is configured to release the engagement between the engaging
portion (112a) and the holding portion (121).
8. The image forming apparatus (10) according to any of claims 1-7, wherein
the transmission mechanism (113) comprises
a plurality of gears (114, 115, 116, 117) comprising a first gear (114) rotatable
around the first shaft (102) and a second gear (117) rotatable around the second shaft
(103), and
a clutch (118) installed between at least one gear from among the plurality of gears
(114, 115, 116, 117) and the rotational shaft of the at least one gear, and
the clutch (118) is configured to switch transmission and non-transmission of rotation
between the at least one gear and the rotational shaft based on a rotational direction
of the at least one gear.
9. The image forming apparatus (10) according to claim 8, wherein
the at least one gear is the second gear (117),
the clutch (118) is configured to switch transmission and non-transmission of rotation
from the second gear (117) to the second shaft (103) based on a rotational direction
of the second gear (117), and
the releasing member (119) is a cam formed integrally with the second gear (117).
10. The image forming apparatus (10) according to any of claims 1-7, wherein
the transmission mechanism (113) comprises a gear rotatable around the second shaft
(103), and
the releasing member (119) is a cam formed integrally with the gear.
11. A method for feeding a sheet from a stack (50) of sheets, comprising:
rotating a first shaft (102) around the first shaft (102);
transmitting rotation of the first shaft (102) only in a first direction (R1) to a
second shaft (103);
feeding a sheet from a stack (50) of sheets by rotating a roller (111) around the
second shaft (103);
connecting, with an arm (112), the first shaft (102) and the second shaft (103);
holding the arm (112) or the roller (111) with the roller (111) away from the stack
(50); and
when the rotation of the first shaft (102) is transmitted to the second shaft (103),
releasing the arm (112) or the roller (111).
12. The method according to claim 11, wherein
the holding comprises pressing, with an elastic portion (122), a holding portion (121)
to the arm (111), and
the releasing presses the holding portion (121) in a direction away from the arm (111)
and releases to hold the arm (111) by the holding portion (121).
13. The method according to claim 11 or claim 12, further comprising
engaging an engaging portion (112a) formed on a tip portion of the arm (111) with
the holding portion (121), wherein
the releasing releases the engagement between the engaging portion (112a) and the
holding portion (121).
14. The method according to any of claims 11-13, further comprising
providing a plurality of gears (114, 115, 116, 117) comprising a first gear (114)
rotatable around the first shaft (102) and a second gear (117) rotatable around the
second shaft (103), and
providing a clutch (118) installed between at least one gear from among the plurality
of gears (114, 115, 116, 117) and the rotational shaft of the at least one gear, wherein
the transmitting comprises switching, with the clutch (118), transmission and non-transmission
of rotation between the at least one gear and the rotational shaft based on a rotational
direction of the at least one gear.