U.S. patent application number 12/048727 was filed with the patent office on 2008-12-04 for sheet takeout device.
This patent application is currently assigned to KABUSHIKI KAISHA TOSHIBA. Invention is credited to Yukio Asari, Yoshihiko Naruoka.
Application Number | 20080296829 12/048727 |
Document ID | / |
Family ID | 39736922 |
Filed Date | 2008-12-04 |
United States Patent
Application |
20080296829 |
Kind Code |
A1 |
Asari; Yukio ; et
al. |
December 4, 2008 |
SHEET TAKEOUT DEVICE
Abstract
A sheet takeout mechanism has a takeout roller that rotates in
contact with a sheet located at a takeout position, and a motor
that intermittently rotates the takeout roller. A triangular
suction port is formed on a suction surface of the takeout roller
and has a vertex located downstream in a rotation direction of the
takeout roller. When a negative pressure is exerted on the sheet
via the suction port, the suction force is weak at the beginning of
suction and then increases gradually.
Inventors: |
Asari; Yukio; (Yokohama-shi,
JP) ; Naruoka; Yoshihiko; (Yokohama-shi, JP) |
Correspondence
Address: |
PILLSBURY WINTHROP SHAW PITTMAN, LLP
P.O. BOX 10500
MCLEAN
VA
22102
US
|
Assignee: |
KABUSHIKI KAISHA TOSHIBA
Tokyo
JP
|
Family ID: |
39736922 |
Appl. No.: |
12/048727 |
Filed: |
March 14, 2008 |
Current U.S.
Class: |
271/95 |
Current CPC
Class: |
B65H 3/10 20130101 |
Class at
Publication: |
271/95 |
International
Class: |
B65H 3/12 20060101
B65H003/12 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 1, 2007 |
JP |
2007-147107 |
Claims
1. A sheet taking-out device comprising: a rotating member having a
suction surface which travels along a sheet fed to a takeout
position and a suction port formed on the suction surface; a
rotating mechanism which intermittently rotates the rotating member
so as to minimize a rotation speed at a timing when the suction
port passes by a suction position where the suction port sucks the
sheet located at the takeout position; a suction mechanism which
allows the suction surface to generate a negative pressure via the
suction port so that the sheet located at the takeout position is
sucked by and contacted with the suction surface when the suction
port passes by the suction position; and suction force adjusting
means which adjusts a suction force applied to the sheet located at
the takeout position via the suction port so as to prevent the
sheet from being sucked and moved by the suction surface while the
suction port is approaching the suction position with the rotation
speed of the rotating member reduced.
2. The sheet takeout device according to claim 1, wherein the
suction force adjusting means adjusts the suction force such that
the sheet located at the takeout position is sucked by and
contacted with the suction surface at a timing when the rotation
speed of the rotating member is minimized to locate the suction
port opposite the sheet.
3. The sheet takeout device according to claim 2, wherein the
suction force adjusting means adjusts the shape of the suction port
such that a downstream aperture area of the suction port is smaller
than an upstream aperture area of the suction port in a rotation
direction of the rotating member.
4. The sheet takeout device according to claim 3, wherein the
suction port is formed to be a triangle having a vertex located
downstream in the rotation direction of the rotating member.
5. The sheet takeout device according to claim 1, wherein the
suction force adjusting means controls the suction mechanism such
that as the suction port approaches the suction position, the
suction force applied via the suction port to the sheet located at
the takeout position increases gradually.
6. The sheet takeout device according to claim 5, wherein the
suction force adjusting means has a valve which turns on and off
the negative pressure and a controller which controls a switching
timing for the valve so as to maximize the suction force at the
timing when the suction port stands opposite the sheet located at
the takeout position.
7. The sheet takeout device according to claim 2, wherein the
suction force adjusting means adjusts the shape of the suction port
such that the downstream aperture area of the suction port is
smaller than the upstream aperture area of the suction port in the
rotation direction of the rotating member, and controls the suction
mechanism such that as the suction port approaches the suction
position, the suction force applied via the suction port to the
sheet located at the takeout position increases gradually.
8. The sheet takeout device according to claim 7, wherein the
suction port is formed to be a triangle having a vertex located
downstream in the rotation direction of the rotating member.
9. The sheet takeout device according to claim 7, wherein the
suction force adjusting means has a valve which turns on and off
the negative pressure and a controller which controls a switching
timing for the valve so as to maximize the suction force at the
timing when the suction port stands opposite the sheet located at
the takeout position.
10. The sheet takeout device according to claim 2, wherein the
rotating member is a substantially cylindrical takeout roller
formed of a rigid body such as metal and having the suction surface
on an outer periphery.
11. The sheet takeout device according to claim 2, wherein the
rotating member is an endless takeout belt wound and extended
around a plurality of rollers.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is based upon and claims the benefit of
priority from prior Japanese Patent Application No. 2007-147107,
filed Jun. 1, 2007, the entire contents of which are incorporated
herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a sheet takeout device
which sucks and contacts a sheet resting at a takeout position and
which then rotates to take out the sheet in a surface
direction.
[0004] 2. Description of the Related Art
[0005] A sheet takeout device is conventionally known which exerts
a negative pressure on one of a plurality of sheets located at a
takeout position, via a belt hole in an endless takeout belt to
suck and contact the sheet and which then allows the takeout belt
to travel intermittently in a takeout direction to take out the
sheet onto a conveying path (see, for example, Japanese patent No.
3735565).
[0006] In addition to the takeout chamber, this device has a
negative pressure chamber located opposite the takeout position
across the takeout belt and a chamber mask located between the
negative pressure chamber and the takeout belt. Two mask holes
separated from each other in a belt traveling direction are formed
in the chamber mask. The mask holes allow a negative pressure to be
exerted twice on the sheet located at the takeout position, via the
belt hole passing intermittently by the takeout position.
[0007] That is, the mask hole located downstream in the takeout
direction has a smaller aperture area than the mask hole located
upstream in the takeout direction. When an operation of taking out
the sheet is started, a relatively high negative pressure is
exerted on the sheet. After the taken-out sheet is delivered to a
downstream conveying mechanism, the suction force applied to the
sheet by the takeout belt is weakened. Thus, a relatively strong
conveying force can be applied to the sheet at the beginning of the
takeout operation. After the sheet is delivered to the downstream
conveying mechanism, the conveyance of the sheet can be prevented
from being obstructed.
[0008] However, this conventional device exerts a negative pressure
on the sheet resting at the takeout position, via the belt hole in
the intermittently driven takeout belt. Thus, when the takeout belt
sucks and contacts the sheet, a relatively high negative pressure
is rapidly exerted on the sheet. Consequently, the sheet may be
skewed or a suction timing may vary. For example, a deviation in
sheet suction timing may vary a sheet takeout pitch.
[0009] Furthermore, this device applies a suction force to the
sheet with a difference in speed remaining between the sheet
resting at the takeout position and the takeout belt. Consequently,
friction occurs between the belt and the sheet, which may
disadvantageously stain or damage the sheet.
BRIEF SUMMARY OF THE INVENTION
[0010] An object of the present invention is to provide a sheet
takeout device which can stabilize an operation of taking out a
sheet and which prevents the sheet from being stained or damaged
during the takeout operation.
[0011] To accomplish the object, a sheet taking-out device
according to an embodiment of the present invention includes a
rotating member having a suction surface which travels along a
sheet fed to a takeout position and a suction port formed on the
suction surface, a rotating mechanism which intermittently rotates
the rotating member so as to minimize a rotation speed at a timing
when the suction port passes by a suction position where the
suction port sucks the sheet located at the takeout position, a
suction mechanism which allows the suction surface to generate a
negative pressure via the suction port so that the sheet located at
the takeout position is sucked by and contacted with the suction
surface when the suction port passes by the suction position, and
suction force adjusting means which adjusts a suction force applied
to the sheet located at the takeout position via the suction port
so as to prevent the sheet from being sucked and moved by the
suction surface while the suction port is approaching the suction
position with the rotation speed of the rotating member
reduced.
[0012] According to the present invention, while the suction port
is approaching the sheet located at the takeout position with the
rotation speed of the rotating member reduced and when there is a
relatively significant difference in speed between the suction port
and the sheet, the suction force applied to the sheet via the
suction port is adjusted so as to prevent the sheet from being
sucked and moved by the suction surface. This makes it possible to
prevent a suction force strong enough to move the sheet located at
the takeout position from being applied to the sheet before the
suction port stands opposite the sheet. Furthermore, a sheet
suction timing can be fixed to allow a sheet takeout timing to be
stabilized.
[0013] Additionally, according to the present invention, the
suction force is adjusted so as to prevent a strong suction force
from being applied to the sheet via the suction port while a
difference in speed remains between the suction port and the sheet.
The sheet is thus prevented from being sucked by and contacted with
the suction surface of the rotating member being decelerated. This
makes it possible to prevent a possible slip between the suction
surface and the sheet, which come into contact with each other, and
to prevent the sheet from being disadvantageously stained or
damaged by friction during the takeout operation.
[0014] Additional objects and advantages of the invention will be
set forth in the description which follows, and in part will be
obvious from the description, or may be learned by practice of the
invention. The objects and advantages of the invention may be
realized and obtained by means of the instrumentalities and
combinations particularly pointed out hereinafter.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
[0015] The accompanying drawings, which are incorporated in and
constitute a part of the specification, illustrate embodiments of
the invention, and together with the general description given
above and the detailed description of the embodiments given below,
serve to explain the principles of the invention.
[0016] FIG. 1 is a schematic diagram of a sheet takeout device
according to a first embodiment of the present invention;
[0017] FIG. 2 is an enlarged view showing the appearance of a
suction port in a takeout roller incorporated in the takeout device
in FIG. 1;
[0018] FIG. 3 is a velocity diagram showing a speed at which the
takeout roller in FIG. 2 is intermittently rotated;
[0019] FIG. 4 is a velocity diagram showing an example in which the
takeout roller is rotated at a low speed when the suction port
passes by a suction position;
[0020] FIG. 5 is a diagram of the appearance of a conventional
takeout roller having a rectangular suction port;
[0021] FIG. 6 is a diagram illustrating problems with the
conventional takeout roller in FIG. 5;
[0022] FIG. 7 is a diagram showing the appearance of a first
variation of the suction port in the takeout roller in FIG. 2;
[0023] FIG. 8 is a diagram showing the appearance of a second
variation of the suction port in the takeout roller in FIG. 2;
[0024] FIG. 9 is a schematic diagram showing the structure of an
essential part of a takeout mechanism according to a second
embodiment of the present invention;
[0025] FIG. 10 is a velocity diagram of the speed at which a
takeout roller in FIG. 9 is intermittently rotated;
[0026] FIG. 11 is a schematic diagram showing a variation of the
takeout roller in FIG. 9;
[0027] FIG. 12 is a schematic diagram showing the structure of an
essential part of a takeout mechanism according to a third
embodiment of the present invention;
[0028] FIG. 13 is a schematic diagram showing a first variation of
the takeout roller in FIG. 12;
[0029] FIG. 14 is a schematic diagram showing a second variation of
the takeout roller in FIG. 12;
[0030] FIG. 15 is a schematic diagram of a takeout mechanism
according to a fourth embodiment of the present invention;
[0031] FIG. 16 is a schematic diagram showing a first variation of
a takeout belt in FIG. 15;
[0032] FIG. 17 is a schematic diagram showing a second variation of
the takeout belt in FIG. 15;
[0033] FIG. 18 is a schematic diagram of a takeout mechanism
according to a fifth embodiment of the present invention;
[0034] FIG. 19 is a schematic diagram showing a variation of a
takeout belt in FIG. 18;
[0035] FIG. 20 is a schematic diagram of a takeout mechanism
according to a sixth embodiment of the present invention; and
[0036] FIG. 21 is a schematic diagram showing a variation of a
takeout belt in FIG. 20.
DETAILED DESCRIPTION OF THE INVENTION
[0037] Embodiments of the present invention will be described below
in detail with reference to the drawings.
[0038] FIG. 1 shows a schematic plan view of a sheet takeout device
1 according to a first embodiment of the present invention
(hereinafter simply referred to as a takeout device 1). FIG. 2 is
an enlarged view of a suction port 3 in a takeout roller 2
incorporated in the takeout device 1. FIG. 3 is an example of a
velocity diagram showing a speed at which the takeout roller 2 is
intermittently rotated.
[0039] As shown in FIG. 1, the takeout device 1 has a loading
section 12 on which a plurality of collected sheets P such as mail
or bills which are to be processed are loaded in an upright
position, a supply mechanism (not shown) which moves the loaded
sheets P in a collecting direction (the direction of arrow F in
FIG. 1) and which feeds a first sheet P1 located at a
moving-direction leading end of the sheets P, to a takeout
position, a takeout mechanism 10 that takes out the sheet P1 fed to
the takeout position, in a surface direction (the direction of
arrow T in FIG. 1), a separating mechanism 16 that applies a
separating torque acting in a direction opposite to the takeout
direction T, to a second sheet and subsequent sheets P which are
carried out with the sheet P1 taken out on a conveying path 14, to
separate the second and subsequent sheets P, and a conveying
mechanism 18 which receives the sheet P having passed through the
separating mechanism 16 and which pulls the sheet P at a speed
slightly higher than a takeout speed to convey the sheet P further
downstream.
[0040] The takeout mechanism 10 has a substantially cylindrical
takeout roller 2 (rotating member) formed of a rigid body such as
metal and which rotates in the direction of arrow R in FIG. 1 in
contact with the sheet P fed to the takeout position by the supply
mechanism (not shown), a pump 4 (suction mechanism) that generates
a negative pressure via a suction port 3 formed in an outer
peripheral surface 2a (suction surface) of the takeout roller 2
which contacts the sheet P1, and a motor 5 (rotating mechanism)
that intermittently rotates the takeout roller 2 in accordance with
the velocity diagram illustrated in FIG. 3.
[0041] The takeout roller 2 is annularly and rotatably installed
around an outer periphery of a generally cylindrical core member 6
containing a negative pressure chamber 6a connected to a pump 4.
The core member 6 is fixedly located such that an opening in the
chamber 6a lies opposite the sheet P1 located at the takeout
position. As shown by a dashed line in FIG. 2, the opening 6b in
the negative chamber 6a is rectangular and has an aperture area
sufficient to cover the entire suction port 3 in the takeout roller
2.
[0042] The takeout roller 2 is intermittently rotated in accordance
with the velocity diagram in FIG. 3 so as to minimize the rotation
speed when the suction port 3 passes by a suction position. In the
present embodiment, the takeout roller 2 is rotated such that the
suction port 3 is stopped at the suction position. That is, the
takeout roller 2 operates such that when the suction port 3
overlaps the opening 6b in the chamber 6a (as shown in FIGS. 1 and
2), the sheet P1 located at the takeout position is sucked by and
contacted with the suction surface 2a of the takeout roller 2. The
pump 4 always generates a fixed negative pressure in the negative
pressure chamber 6a. The sheet P sucked by and contacted with the
suction surface 2a of the takeout roller 2 is taken out in the
surface direction T by rotation of the takeout roller 2. Thus, when
the suction port 3 is located opposite the sheet located at the
takeout position, the rotation of the takeout roller 2 is stopped
and a sufficient negative pressure is exerted on the sheet P. The
sheet P can be reliably sucked by and contacted with the suction
surface 2a of the takeout roller 2, allowing the takeout operation
to be stabilized.
[0043] In the present embodiment, the one suction port 3 is formed
on the suction surface 2a of the takeout roller 2 to allow one
sheet P to be taken out every time the takeout roller 2 makes one
rotation. However, a plurality of the suction port 3 may be formed
in a traveling direction of the suction surface 2a to allow a
plurality of the sheets P to be taken out while the takeout roller
2 is making one rotation. In this case, the takeout roller 2 needs
to be intermittently rotated so as to temporarily stop the takeout
roller 2 every time one of the suction ports 3 stands opposite the
sheet P located at the takeout position.
[0044] Furthermore, the velocity diagram in FIG. 3 shows that the
rotation speed of the takeout roller 2 is zeroed at a timing when
the suction port 3 passes by the suction position, where the
suction port sucks and contacts the sheet P1 located at the takeout
position. However, for example, as shown in FIG. 4, the takeout
roller 2 may be rotated at a low speed (for example, 50 [rad/s])
when the suction port 3 passes by the suction position. In either
case, the speed of the takeout roller 2 may be reduced such that
the difference in speed between the suction surface 2a of the
takeout roller 2 and the sheet P becomes small enough to allow the
suction port 3 to reliably suck and contact the sheet P located at
the takeout position.
[0045] As shown in FIG. 2, the suction port 3, formed on the
suction surface 2a of the takeout roller 2 according to the present
embodiment, is formed to be an isosceles triangle having a vertex
positioned most downstream in a rotation direction R of the takeout
roller 2. The shape of the suction port 3 is not limited to the
isosceles triangle but may be such that the downstream aperture
area of the suction port 3 is at least smaller than the upstream
aperture area of the suction port 3 in the rotation direction of
the takeout roller 2.
[0046] The opening 6b in the chamber 6a in the core member 6, which
overlaps the suction port 3, is formed to be a rectangle having a
rotating-direction width that is at least larger than the height of
the isosceles triangle of the suction port 3 and an axial length
that is at least larger than the length of the base of the
isosceles triangle. Ideally, the opening 6b desirably has a width
that is slightly larger than the height of the isosceles triangle
and a length that is slightly larger than the length of the base of
the isosceles triangle. This prevents the possible loss of the
negative pressure and allows the suction hole 3 to efficiently
generate a negative pressure. Negative pressure control can thus be
performed depending on the shape of the suction hole 3 not relate
to the rotating position of the suction hole 3.
[0047] In the present embodiment, the suction port 3 is shaped as
described above. Thus, while the suction port 3 is approaching the
suction position with the rotation speed of the takeout roller 2
gradually reduced, that is, when the suction port 3 starts to
overlap the opening 6b in the negative pressure chamber 6a and it
is too early to suck the sheet P, an undesired force applied to the
sheet P1 located at the takeout position is weakened via the
suction port 3. That is, the shape of the suction port 3 functions
as suction force adjusting means according to the present
invention.
[0048] Before describing the characteristic configuration (suction
port 3) of the present embodiment in detail, description will be
given of problems with a conventional takeout roller with a
rectangular suction port with reference to FIGS. 5 and 6. The
opening in the core member, around which the takeout roller is
annularly installed, is also rectangular. In this case, discussion
will be given of the case in which with a suction force applied to
the sheet P located at the takeout position, via a rectangular
suction port 21 shown in FIG. 5(b), the takeout roller 2 is
intermittently rotated to take out the sheet P in the surface
direction, as shown in FIG. 5(a).
[0049] In this case, when the suction port 21 approaching the
suction position with the takeout roller 2 decelerated starts to
overlap the opening in the negative pressure chamber 6a, a
relatively strong suction force starts to act on the sheet P with a
significant difference in speed remaining between the suction port
21 and the sheet P. That is, with the rectangular suction port 21,
when the starts to overlap the opening in the negative pressure
chamber 6a, a negative pressure acts all over a relatively long
area in the axial direction of the takeout roller 2.
[0050] Thus, as shown in the left of FIG. 6(a), an operation of
taking out the sheet P sucked by and contacted with the takeout
roller 2 is not always started at a timing when the suction port 21
in the takeout roller 2 stands opposite the sheet P located at the
takeout position so as to cover the largest area of the sheet P (at
this timing, the takeout roller according to the present embodiment
is stopped).
[0051] That is, for example, it is assumed that during the
deceleration of the takeout roller 2, the sheet P is sucked by and
contacted with the suction surface 2a of the takeout roller 2 with
a difference in speed remaining between the suction port 21 and the
sheet P located at the takeout position, as shown in the left of
FIG. 6(b). In this case, before the takeout roller 2 is stopped,
the sheet P has been moved slightly in the takeout direction. When
the takeout roller 2 is rotated to start the operation of taking
out the sheet P in this condition, then as shown in the right of
FIGS. 6(a) and 6(b), the takeout-direction leading end of the sheet
P taken out on the conveying path 14 is misaligned when the suction
port 21 is separated from the sheet P. Furthermore, the opposite is
true if the timing for sucking the sheet P is slightly delayed, as
shown in FIG. 6(c). Thus, a deviation in the sheet takeout timing
may disturb the gaps or pitches between the consecutively taken-out
sheets.
[0052] Moreover, as described above, when an attempt is made to
allow the suction surface 2a of the takeout roller 2 to suck the
sheet P located at the takeout position with a difference in speed
remaining between the suction port 21 and the sheet P, slippage may
occur between the sheet P and the suction surface 2a to
disadvantageously cause the surface of the sheet P to be stained or
damaged.
[0053] Thus, in the present embodiment, the suction port 3 is
triangular, as shown in FIG. 2, so as to minimize the overlapping
area of the suction port 3 when the suction port 3 starts to
overlap the opening in the negative pressure chamber 6a and then to
gradually increase the sucking area of the suction port 3. This
minimizes the suction force applied to the sheet P located at the
takeout position with a difference in speed remaining between the
suction port 3 and the sheet P located at the takeout position.
[0054] Specifically, in the vicinity of the end of deceleration of
the takeout roller 2 corresponding to each of the shaded portions
in the velocity diagram in FIG. 3, a small opening part of the
suction port 3 located on the left side of a dashed line L in FIG.
2 lies opposite the sheet P located at the takeout position. After
the takeout roller 2 is stopped and when the taking-out of the
sheet P is started, a relatively large opening part of the suction
port 3 located on the right side of the dashed line L in FIG. 2
lies opposite the sheet P.
[0055] This makes it possible to prevent a strong suction force
from being applied via the suction port 3 to the sheet P located at
the takeout position, during the deceleration of the takeout roller
2 before stoppage. The suction timing for the sheet P can thus
stabilized. That is, all the sheets P can be taken out using a
fixed timing, allowing the sheets P to be taken out at a fixed
pitch. Furthermore, the present embodiment can minimize the
difference in speed between the suction port 3 and the sheet P
(according to the present embodiment, the difference is almost
zero) when the sheet P located at the takeout position is sucked by
the suction surface 2a of the takeout roller 2. This prevents a
possible slip between the suction port 3 and the sheet P and thus
prevents the sheet from being stained or damaged during the takeout
operation.
[0056] Furthermore, the suction port 3 according to the present
embodiment makes it possible to inhibit the possible skew of the
sheet P during the takeout operation.
[0057] With the conventional rectangular suction port 21, described
with reference to FIG. 5, when the suction port 21 starts to
overlap the opening in the negative pressure chamber 6a with the
takeout roller 2 decelerated, a relatively strong suction force is
applied to the sheet P over a relatively wide range in the axial
direction of the takeout roller 2. Thus, if the sheet P located at
the takeout position is already skewed, the sheet P is likely to be
rotated in a direction in which the skew becomes more
significant.
[0058] In contrast, with the suction port 3 according to the
present embodiment, a weak suction force is first applied through
the vertex of the triangle. Thus, even if the sheet is skewed
before the takeout operation, the skew is unlikely to be become
more significant. Thus, the skew of the taken-out sheet can be
easily corrected.
[0059] When a plurality of sheets P in a fixed regular form are to
be taken out, the triangle of the suction port 3 is designed such
that the vertex of the triangle lies on a line in the takeout
direction which passes through the centroid of the sheets P loaded
via the loading section 12. This makes it possible to eliminate the
skew of the sheet P during the takeout operation. That is, by
exerting a negative pressure on an area on a line in the takeout
direction which passes through the centroid of the sheet P, it is
possible to take out the sheet P with the posture assumed by the
sheet P before the takeout operation maintained. Thus, if the sheet
P is not skewed before the takeout operation, the sheet P can be
taken out in a non-skewed posture.
[0060] In contrast, with the conventional rectangular suction port
21, even if the sheet P is not skewed before the takeout operation,
the sheet P may be skewed during the takeout operation. That is,
the conventional suction port 21 exerts a negative pressure over a
relatively wide range in the axial direction of the takeout roller
2. Consequently, a negative pressure may start to be exerted
earlier on areas other than the one on the line in the takeout
direction which passes through the centroid of the sheet P. When
the negative pressure acts on a position located away from the line
of the sheet P, a moment is generated to rotate and skew the sheet
P.
[0061] Moreover, the present embodiment allows the pump 4 to be
always operated to always draw a vacuum from the negative pressure
chamber 6a. The above-described effects inherent in the present
invention can be exerted simply by modifying the shape of the
suction port 3. That is, the present embodiment allows the suction
force to be controlled simply by changing the device configuration
and without the need to precisely control the negative
pressure.
[0062] FIG. 7 shows a first variation of the suction port 3 in the
takeout roller 2 according to the first embodiment. This takeout
roller 2' is different from the takeout roller 2 in the first
embodiment in that the takeout roller 2' has a plurality of
circular suction ports 22 with different aperture areas. The
remaining part of the configuration is substantially the same as
that of the first embodiment. Thus, components of the first
variation which function similarly to those of the first embodiment
are denoted by the same reference numerals and will not be
described in detail.
[0063] A suction port 22 in the takeout roller 2' has circular
holes having a relatively small aperture area and arranged
downstream in the rotation direction R of the takeout roller 2' and
circular holes having a relatively large aperture area and arranged
upstream in the rotation direction R. When the suction port 22 is
composed of the circular holes with the plurality of different
aperture areas, the downstream aperture area can be set smaller
than the upstream area as is the case with the first embodiment,
described above. This enables a reduction in the aperture area of
the part of the suction port 2 which approaches the sheet P earlier
during the deceleration of the takeout roller 2'. As a result,
effects similar to those of the first embodiment, described above,
can be exerted.
[0064] Furthermore, according to the first variation, the suction
port 22 is composed of the combination of the plurality of holes.
Thus, compared to the first embodiment, described above, the first
variation is expected to exert an appropriate edge effect between
the sheet P sucked by and contacted with the suction surface 2a and
the suction port 22. That is, the increased length of the edge of
the suction port, which sucks the sheet P, correspondingly
increases the length of the edge contacting the sheet P. This
allows a stronger conveying force to be applied to the sheet P via
the suction surface 2a, making it possible to inhibit a possible
slip between the suction surface 2a and the sheet P.
[0065] However, in view of the peel property of the sheet P
released from the suction surface 2a after the sheet P has been
taken out, the elasticity of the sheet P, and the like, it is
necessary to appropriately select the aperture area and shape of
the suction port according to the surface condition of the sheets
to be processed and the elasticity of the sheets.
[0066] FIG. 8 shows a second variation of the suction port 3 in the
takeout roller 2 according to the first embodiment, described
above. This takeout roller 2'' is different from the takeout roller
2 according to the first embodiment, described above, in that a
large number of circular suction ports 23 with the same aperture
area are arranged with the arrangement density of the suction ports
varied. The remaining part of the configuration is substantially
the same as that of the first embodiment. Thus, components of the
second variation which function similarly to those of the first
embodiment are denoted by the same reference numerals and will not
be described in detail.
[0067] The suction ports 23 in the takeout roller 2'' are arranged
such that the downstream arrangement density is lower (sparser)
than the upstream arrangement density in the rotation direction R
of the takeout roller 2''. When the arrangement density of the
large number of suction ports 23 is thus varied, it is possible to
reduce the aperture area of the part of the suction port 2 which
approaches the sheet P earlier during the deceleration of the
takeout roller 2'', as is the case with the first embodiment,
described above. As a result, effects similar to those of the first
embodiment, described above, can be exerted.
[0068] In the embodiment described above, the suction force applied
to the sheet P located at the takeout position is adjusted by
modifying the shape of the suction port 3, 22, or 23 or the hole
arrangement pattern. However, similar effects can be exerted by
modifying the shape of the opening in the negative pressure chamber
6a in the core member 6, around which the takeout roller 2 is
annularly installed, as described above. For example, similar
effects can be exerted by forming the conventional rectangular
suction port 21, described with reference to FIG. 5, on the suction
surface 2a of the takeout roller 2 and forming the opening in the
negative chamber 6a to be triangular. In this case, the opening in
the negative pressure chamber 6a may be shaped like a triangle
having a vertex located upstream in the rotation direction of the
takeout roller 2.
[0069] Now, a takeout mechanism 20 according to a second embodiment
will be described with reference to FIGS. 9 and 10. FIG. 9 is an
enlarged view of the suction port 21 in the takeout roller 2
according to the present embodiment. FIG. 10 shows a velocity
diagram showing the rotation speed of the takeout roller 2. Also in
this case, components of the second embodiment which function
similarly to those of the first embodiment are denoted by the same
reference numerals and will not be described in detail.
[0070] As shown in FIG. 9, the rectangular suction form 21 as
described in FIG. 5 is formed on the suction surface 2a of the
takeout roller 2 according to the present embodiment. A solenoid
valve 25 that turns on and off air suction is attached to the
middle of a pipe connecting the negative pressure chamber 6a and
the pump 4 together. A controller 27 is connected to the solenoid
valve 25 to controllably turn on and off the solenoid valve 25 on
the basis of information on the rotational position of the takeout
roller 2.
[0071] The takeout roller 2 according to the present embodiment is
also rotationally driven in accordance with the velocity diagram in
FIG. 10. That is, the takeout roller 2 is intermittently rotated so
as to minimize the rotation speed of the takeout roller 2 (in the
present embodiment, zero the rotation speed) at the timing when the
suction port 21 stands opposite the sheet P located at the takeout
position.
[0072] Continuous generation of a negative pressure via the
rectangular suction port 21 may result in various problems as in
the case of the conventional example, described with reference to
FIGS. 5 and 6. Thus, in the present embodiment, the solenoid valve
25 is switched at a specific timing to control the suction force
applied during the deceleration of the takeout roller 2. That is,
in the present embodiment, the solenoid valve 25 and the controller
27, which switches the solenoid valve 25, function as suction force
adjusting means.
[0073] Specifically, in the present embodiment, the controller 27
turns off the solenoid valve at timings shown by shaded portions in
FIG. 10 to suspend the suction of air. In other words, the solenoid
valve 25 is turned on immediately before the rotation speed of the
takeout roller 2 is zeroed, to start the suction of air. Only a low
negative pressure is generated in the suction port 21 immediately
after the suction of air is started by switching the solenoid valve
25. The suction force increases gradually as the time elapses.
[0074] Thus, switching the solenoid valve 25 at a timing
immediately before the stoppage, shown in FIG. 10, enables a
gradual increase in the suction force applied to the sheet P via
the suction port 21 in the takeout roller 2 being decelerated. This
makes it possible to exert effects similar to those of the first
embodiment, described above. In particular, in the present
embodiment, the switching timing for the solenoid valve 25 is
controlled so as to maximize the suction force at the timing when
the suction port 21 stands opposite the sheet P located at the
takeout position. That is, the present embodiment can prevent the
sheet P from being sucked by the suction surface 2a during the
deceleration of the takeout roller 2 and also prevent the sheet P
from being stained or damaged as a result of the friction between
the suction surface 2a and the sheet P.
[0075] With the solenoid valve 25, the sheet can be reliably sucked
by and contacted with the suction surface 2 by stopping the takeout
roller 2 with the suction port 21 lying opposite the sheet P
located at the takeout position and then turning on the solenoid
valve 25. However, to take out the sheets P at a high speed and a
short pitch, it is necessary to minimize the time for which the
takeout roller 2 is stopped. This requires valve control as
performed in the present embodiment.
[0076] FIG. 11 shows a variation of the takeout roller 2 according
to the second embodiment, described above. The takeout roller 2 has
a suction port 2 composed of a combination of a large number of
holes aligned in a matrix. This variation can exert effects similar
to those of the takeout roller according to the second embodiment
by allowing the controller 27 to control the solenoid valve 25 at
the same timings as those in the second embodiment, described
above. Furthermore, compared to the second embodiment, the
variation can enhance the edge effect owing to the increased length
of the edge of the hole. This enables an increase in the conveying
force that can be applied to the sheet P.
[0077] FIG. 12 shows the structure of an essential part of a
takeout mechanism 30 according to a third embodiment. The takeout
mechanism 30 has a structure in which the takeout mechanism 10
according to the first embodiment, described above, is combined
with the takeout mechanism 20 according to the second embodiment,
described above. That is, the takeout mechanism 30 has the
triangular suction port 3 on the suction surface 2a of the takeout
roller 2 and the solenoid valve 25 on the pipe between the negative
pressure chamber 6 and the pump 4. The solenoid valve 25 is also
turned off at the timings shown by the shaded portions in the
velocity diagram in FIG. 10. Also in this case, components of this
variation which function similarly to those of the above-described
embodiments are denoted by the same reference numerals and will not
be described in detail.
[0078] Thus, the third embodiment combines the triangular suction
port 3 with the solenoid valve 25 to enable an increase in the
takeout speed for the sheet P compared to the first and second
embodiments. That is, a reduction in the takeout pitch of the
sheets P in the takeout mechanism 20 according to the second
embodiment, described with reference to FIGS. 9 and 10, reduces the
time for which the solenoid valve 25 remains off, that is, the area
of the shaded portions in FIG. 10. Consequently, the next suction
operation may be started before the negative pressure becomes equal
to the atmospheric pressure. In this case, the suction force
applied to the sheet P located at the takeout position starts to
increase simultaneously with the generation of a negative pressure
during the deceleration of the takeout roller 2. This may
disadvantageously cause the sheet to be misaligned, stained, or
damaged. That is, with the structure of the second embodiment, the
takeout speed is limited.
[0079] In contrast, when the suction port 3 is triangular, as is
the case with the present embodiment, even if the takeout speed for
the sheet P is increased enough to start the next suction before
the negative pressure in the negative pressure chamber 6a returns
to atmospheric pressure, a strong suction force can be prevented
from being applied to the sheet P during the deceleration of the
takeout roller 2. This makes it possible to prevent the sheet P
from being misaligned, stained, or damaged. Thus, the takeout
mechanism 30 according to the present embodiment can increase the
takeout speed for the sheet P compared to the takeout mechanisms 10
and 20 according to the first and second embodiments, described
above.
[0080] FIG. 13 shows a first variation of the takeout roller
according to the third embodiment. FIG. 14 shows a second
variation. A large number of holes with different aperture areas
are formed on the suction surface 2a of the takeout roller 2 in
FIG. 13 as suction ports 32. Suction ports 34 with the same area
are arranged on the suction surface 2a of the takeout roller 2 in
FIG. 14 with the arrangement density of the suction ports varied.
The suction ports 32 and 34 according to the first and second
variations can function similarly to the suction ports 3 in the
takeout roller 2 according to the third embodiment to exert effects
similar to those of the third embodiment.
[0081] When the suction port is formed of the plurality of small
holes 32 or 34 as in the case of the first and second variations,
an inelastic sheet P can be prevented from being excessively drawn
into the holes. In contrast, with the triangular suction port 3,
described with reference to FIG. 12, if the suction force of the
pump 4 is too strong or the sheet P is inelastic, the sheet P is
drawn into the suction port 3 in an undesired manner. In this case,
the sheet P may be stained, damaged, or inappropriately peed off.
Thus, if an inelastic sheet P is to be processed, the suction port
32 or 34, composed of the combination of the plurality of holes, is
desirably used as is the case with the variations shown in FIGS. 13
and 14.
[0082] Additional advantages and modifications will readily occur
to those skilled in the art. Therefore, the invention in its
broader aspects is not limited to the specific details and
representative embodiments shown and described herein.
[0083] Accordingly, various modifications may be made without
departing from the spirit or scope of the general inventive concept
as defined by the appended claims and their equivalents.
[0084] For example, in the description of the first to third
embodiments, the takeout roller 2 is used as a rotating member
rotating in contact with the sheet P located at the takeout
position. However, the present invention is not limited to this. An
endless takeout belt may be used as a rotating member as shown in
FIGS. 15 to 21.
[0085] For example, FIG. 15(a) is a schematic plan view of an
essential part of a takeout mechanism 40 according to a fourth
embodiment of the present invention corresponding to the takeout
mechanism 10 according to the present embodiment, described above,
in which the takeout roller 2 is replaced with a takeout belt 42.
FIG. 15(b) is a side view of the essential part of the takeout
mechanism 40 as viewed from the takeout position. The takeout belt
42 is wound and extended around a plurality of rollers 41 and is
allowed to travel endlessly along the sheet P located at the
takeout position. A negative pressure chamber 44 is located
opposite the sheet P located at the takeout position, across the
takeout belt, that is, the negative pressure chamber 44 is located
inside the takeout belt 42. The negative pressure chamber 44 is
fixedly mounted with an opening 46 facing the takeout position.
[0086] A suction port 48 is formed in the takeout belt 42 and
passes by the opening 46 in the negative pressure chamber 44 when
the speed is minimized during traveling. The suction port 48 in the
takeout belt 42 according to the present embodiment is triangular,
as is the case with the first embodiment, described above.
[0087] That is, the present embodiment can control the suction
force applied to the sheet P located at the takeout position, when
the deceleration of the takeout belt 42 is about to end. This makes
it possible to prevent the sheet P from being misaligned, stained,
or damaged.
[0088] Likewise, FIG. 16 shows the structure of a first variation
of the fourth embodiment, described above. FIG. 17 shows the
structure of a second variation. These variations can function
similarly to the variations of the first embodiment, described
above, and exert effects similar to those of the variations of the
first embodiment except that the takeout belt 42 is used in place
of the takeout roller 2.
[0089] FIG. 18(a) is a plan view of a takeout mechanism 50
according to a fifth embodiment of the present invention which
functions similarly to the takeout mechanism 20 according to the
second embodiment, described above. FIG. 18(b) is a side view of
the takeout mechanism 50 according to the fifth embodiment. The
takeout mechanism 50 has a takeout belt 52 with a rectangular
suction port 58, a solenoid valve 55 that turns on and off a
negative pressure generated via an opening 56 in a negative
pressure chamber 54, and a controller 57. The takeout mechanism 50
can function similarly to the takeout mechanism 20 according to the
second embodiment, described above, and exert effects similar to
those of the takeout mechanism 20.
[0090] FIG. 19 shows a takeout mechanism 50' according to a
variation of the fifth embodiment, described above. A suction port
59 is formed on a takeout belt 52 according to this variation and
has a large number of aligningly arranged holes with the same area,
as is the case with the variation of the second embodiment,
described above. The takeout mechanism 50' can function similarly
to the variation of the second embodiment, described with reference
to FIG. 11, and exert effects similar to those of the variation of
the second embodiment.
[0091] FIG. 20 shows a schematic diagram of a takeout mechanism 60
according to a sixth embodiment of the present invention. The
structure of the takeout mechanism 60 corresponds to that of the
takeout mechanism 30 according to the third embodiment, described
with reference to FIG. 12, in which the takeout roller 2 is
replaced with a takeout belt 62. The remaining part of the
structure of the takeout mechanism 60 is similar to that of the
takeout mechanism 30, and the takeout mechanism 60 functions
similarly to the takeout mechanism 30. The takeout mechanism 60
enables an increase in the takeout speed for the sheet P and thus
in processing speed compared to the takeout mechanism 40 according
to the fourth embodiment, described above, and the takeout
mechanism 50 according to the fifth embodiment, described
above.
[0092] FIG. 21 shows a variation of the sixth embodiment, described
above. This takeout mechanism 60' has a suction port 67 with a
large number of holes with different aperture areas instead of the
triangular suction port 63 in the takeout mechanism 60, described
above. The takeout mechanism 60' can function similarly to the
takeout mechanism described with reference to FIG. 13 and exert
effects similar to those of the takeout mechanism described with
reference to FIG. 13.
[0093] As described above, even if the takeout belt is used as a
rotating member that contacts the sheet P located at the takeout
position, effects can be exerted which are similar to those exerted
when the takeout roller is used. The takeout timing for the sheet P
can be prevented from deviating, enabling the pitches or gaps
between the sheets P to be stabilized. The sheet P can also be
prevented from being stained or damaged as a result of a difference
in speed between the belt and the sheet P.
* * * * *