U.S. patent application number 11/699882 was filed with the patent office on 2007-08-02 for overlap detection apparatus and overlap detection method.
This patent application is currently assigned to RYOBI LTD.. Invention is credited to Masamichi Sasaki, Yoshinori Teraoka.
Application Number | 20070176355 11/699882 |
Document ID | / |
Family ID | 38282385 |
Filed Date | 2007-08-02 |
United States Patent
Application |
20070176355 |
Kind Code |
A1 |
Sasaki; Masamichi ; et
al. |
August 2, 2007 |
Overlap detection apparatus and overlap detection method
Abstract
An overlap detection apparatus mounted to a printing press
includes a sheet detection sensor for detecting whether a portion
of the sheets passing a given position is a non-overlapping portion
or an overlapping portion; a signal output section for outputting
an overlapping signal on the basis of the detected results of the
sheet detection sensor, in which the overlapping signal takes a
first form for the overlapping portion and takes a second form for
the non-overlapping portion; and a determination section for
determining that the sheets of paper are being correctly conveyed
while each being displaced by a given amount from an upstream sheet
of paper in the conveying direction and overlapping the same when a
portion of the overlapping signal taking the first form is equal to
a given reference portion, and determines that the sheets of paper
are not being correctly conveyed when the portion of the
overlapping signal taking the first form is not equal to the given
reference portion.
Inventors: |
Sasaki; Masamichi;
(Hiroshima-ken, JP) ; Teraoka; Yoshinori;
(Hiroshima-ken, JP) |
Correspondence
Address: |
TECHNOLOGY & INTELLECTUAL PROPERTY;STRATEGIES GROUP PC dba TIPS GROUP
P. O. BOX 1639
LOS ALTOS
CA
94023-1639
US
|
Assignee: |
RYOBI LTD.
Hiroshima-ken
JP
|
Family ID: |
38282385 |
Appl. No.: |
11/699882 |
Filed: |
January 29, 2007 |
Current U.S.
Class: |
271/183 |
Current CPC
Class: |
B41F 21/05 20130101;
B65H 2513/50 20130101; B65H 2511/524 20130101; B65H 2513/11
20130101; B41F 33/06 20130101; B65H 2513/512 20130101; B65H 2513/11
20130101; B65H 2513/50 20130101; B65H 2513/511 20130101; B65H
2553/51 20130101; B65H 7/125 20130101; B65H 7/06 20130101; B65H
2513/512 20130101; B65H 2513/511 20130101; B65H 2511/524 20130101;
B65H 2220/03 20130101; B65H 2220/03 20130101; B65H 2220/11
20130101; B65H 2220/01 20130101; B65H 2220/02 20130101; B65H
2220/03 20130101; B65H 2220/01 20130101 |
Class at
Publication: |
271/183 |
International
Class: |
B65H 29/68 20060101
B65H029/68 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 31, 2006 |
JP |
2006-021798 |
Claims
1. An overlap detection apparatus mounted to a printing press in
which sheets of paper are successively conveyed while each being
displaced by a given amount from an upstream sheet of paper in a
sheet conveying direction and overlapping the same, comprising: a
sheet detection sensor for detecting whether a portion of the
sheets passing a given position is a non-overlapping portion or an
overlapping portion; a signal output section for outputting an
overlapping signal on the basis of the detected results of the
sheet detection sensor, in which the overlapping signal takes a
first form for the overlapping portion and takes a second form for
the non-overlapping portion; and a determination section for
determining that the sheets of paper are being correctly conveyed
while each being displaced by a given amount from an upstream sheet
of paper in the conveying direction and overlapping the same when a
portion of the overlapping signal taking the first form is equal to
a given reference portion, and determines that the sheets of paper
are not being correctly conveyed when the portion of the
overlapping signal taking the first form is not equal to the given
reference portion.
2. An overlap detection apparatus mounted to a printing press in
which sheets of paper are successively conveyed while each being
displaced by a given amount from an upstream sheet of paper in a
sheet conveying direction and overlapping the same, comprising: a
sheet detection sensor for detecting whether a portion of the
sheets passing a given position is a non-overlapping portion or an
overlapping portion; a signal output section for outputting an
overlapping signal on the basis of the detected result of the sheet
detection sensor, in which the overlapping signal takes a first
form for the overlapping portion and takes a second form for the
non-overlapping portion; and a determination section for
determining that the sheets of paper are being correctly conveyed
while each being displaced by a given amount from an upstream sheet
of paper in the conveying direction and overlapping the same, when
the timing, at which the form of the overlapping signal is changed
from the first form to the second form or vice versa, relative to a
printing reference of the printing press, is equal to a given
reference timing; and determines that the sheets of paper are not
being correctly conveyed, when the timing, at which the form of the
overlapping signal is changed from the first form to the second
form or vice versa, relative to the printing reference of the
printing press, is not equal to the given reference timing.
3. The overlap detection apparatus according to claim 2, wherein
the printing press includes a sheet feeding cylinder, and an
encoder that outputs a rotation signal with reference to the
rotation of the sheet feeding cylinder, and the rotation signal
output by the encoder is employed as the printing reference of the
printing press.
4. The overlap detection apparatus according to any one of claims 1
and 2, wherein the printing press includes a feeder board that
conveys the sheets of paper placed thereon towards a downstream
side; the sheet detection sensor comprises a pair of upper and
lower members disposed vertically with a downstream end of the
feeder board therebetween so as to detect whether a portion of the
sheets passing between the upper and lower members of the sheet
detection sensor is the non-overlapping portion or the overlapping
portion.
5. The overlap detection apparatus according to any one of claims 1
and 2, wherein the overlapping signal takes an H form for the
overlapping sheet portion and takes an L form for the
non-overlapping portion.
6. The overlap detection apparatus according to any one of claims 1
and 2, wherein the printing press includes a feeder board that
conveys the sheets of paper placed thereon towards a downstream
side; the determination section outputs a stop signal when it
determines that the sheets of paper are not being correctly
conveyed; and the printing press further includes a feeder board
stop device that stops the feeder board on the basis of the stop
signal.
7. The overlap detection apparatus according to any one of claims 1
and 2, wherein the printing press includes a feeder board that
conveys the sheets of paper placed thereon towards a downstream
side; and the determination section outputs an annunciation signal
when it determines that the sheets of paper are not being correctly
conveyed; and the printing press further includes an annunciation
device that is actuated on the basis of the annunciation
signal.
8. The overlap detection apparatus according to any one of claims 1
and 2, wherein the signal output section comprises an
amplifier.
9. An overlap detection method of determining whether or not sheets
of paper are being correctly conveyed in a printing press, in which
the sheets of paper are conveyed while each being displaced by a
given amount from an upstream sheet of paper in a sheet conveying
direction and overlapping the same, on the basis of detection of an
overlapping state of the sheets of paper, comprising: detecting
whether a portion of the sheets passing a given position is a
non-overlapping portion or an overlapping portion by a sheet
detection sensor; outputting an overlapping signal on the basis of
the detected result of the sheet detection sensor, in which the
overlapping signal takes a first form for the overlapping portion;
and determining that the sheets of paper are being correctly
conveyed while each being displaced by a given amount from an
upstream sheet of paper in the conveying direction and overlapping
the same when a portion of the overlapping signal taking the first
form is equal to a given reference portion, and determining that
the sheets of paper are not being correctly conveyed when the
portion of the overlapping signal taking the first form is not
equal to the given reference portion.
10. An overlap detection method of determining whether or not
sheets of paper are being correctly conveyed in a printing press,
in which the sheets of paper are conveyed while each being
displaced by a given amount from an upstream sheet of paper in a
sheet conveying direction and overlapping the same, on the basis of
detection of an overlapping state of the sheets of paper,
comprising: detecting whether a portion of the sheets passing a
given position is a non-overlapping portion or an overlapping
portion by a sheet detection sensor; outputting an overlapping
signal on the basis of the detected result of the sheet detection
sensor, in which the overlapping signal takes a first form for the
overlapping portion and takes a second form for the non-overlapping
portion; and determining that the sheets of paper are being
correctly conveyed while each being displaced by a given amount
from an upstream sheet of paper in the conveying direction and
overlapping the same when the timing, at which the form of the
overlapping signal is changed from the first form to the second
form or vice versa, relative to a printing reference of the
printing press, is equal to a given reference timing, and
determining that the sheets of paper are not being correctly
conveyed when the timing, at which the form of the overlapping
signal is changed from the first form to the second form or vice
versa, relative to the printing reference of the printing press, is
not equal to the given reference timing.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application claims priority from Japanese Patent
Application No. 2006-21798, which is incorporated herein by
reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to an overlap detection
apparatus and an overlap detection method that are capable of
detecting whether a sheet conveyed is a single or not.
[0004] 2. Related Art
[0005] A hitherto known overlap detection apparatus, which includes
a sheet conveying section for successively conveying sheets of
paper (hereinafter referred simply to sheets), while each being
displaced by a given amount from an upstream sheet in a conveying
direction and overlapping the same, and a printing section for
printing on sheets fed one by one from the sheet conveying section,
includes a sheet detection sensor for detecting whether a sheet
passing a given position is a single or not, a signal output
section for outputting at periodic intervals overlapping signals
that each take a first form (e.g., an H form) when the sensed sheet
is a double or other multiple and each take a second form (e.g., an
L form) when the sensed sheet is a single, and a determination
section for determining on the basis of the detected result that
sheets are being correctly conveyed while each being displaced by a
given amount from an upstream sheet in the conveying direction and
overlapping the same when an overlapping signal takes the second
form and determining that the sheets are being not correctly
conveyed when an overlapping signal takes the first form. The
apparatus of this type is disclosed in Japanese Patent Application
Laid-open No. Hei-11-180595.
[0006] In the overlap detection apparatus of the type mentioned
above, when sheets each are passing a given position, the sheet
detection sensor detects whether each passing sheet is a single or
not. Then, on the basis of the detected result of the sheet
detection sensor, overlapping signals are output by the signal
output section at given periodic intervals.
[0007] The overlapping signals are output at given period
intervals, such as periodic intervals at which single sheets are to
pass a given position, and take a first form when sheets overlap
each other and takes a second form when sheets do not overlap each
other.
[0008] The output overlapping signals are input into the
determination section, which in turn determines that the sheets are
being correctly conveyed for the second form and determines that
the sheets are not being correctly conveyed for the first form.
[0009] Thus, according to the conventional overlap detection
apparatus, for example, overlapping signals are output at given
periodical intervals, such as periodic intervals at which single
sheets are to pass a given position, and when an overlapping signal
takes the first form representative of that the sheet is a double
or other multiple, the determination is made so that sheets are not
being correctly conveyed. Whereby, a trouble in sheet feeding, such
as a trouble of feeding multiple sheets to the printing section at
a time, is detected.
[0010] Such a sheet feeding trouble in a printing press is caused
when a sheet passing the given position is a double or multiple at
periodic intervals at which single sheets are to pass the given
position, and sometimes caused when a sheet is displaced from an
upstream sheet by an amount greater or small than a given amount in
the sheet conveying direction and overlaps the same. In the latter
case, a trouble of feeding double or multiple sheets to the
printing section at a time or a trouble of feeding no sheet at a
timing at which a sheet must be fed, may be caused.
[0011] However, according to the conventional overlap detection
apparatus, overlapping signals are output at given periodical
intervals such as periodic intervals at which single sheets are to
pass the given position. Therefore, even when a sheet is conveyed
while being displaced from an upstream sheet by an amount greater
or smaller than a given amount and overlapping the same and a
non-overlapping portion (single sheet portion) of these sheets
happens to pass the given position at a timing at which single
sheets are to pass the given position following the given periodic
intervals, an overlapping signal takes the second form (e.g., the L
form). As a result, the determination section may determine that
the sheets are being correctly conveyed even when it is not being
correctly conveyed in the actual operation.
[0012] It is an object of the present invention to provide an
overlap detection apparatus and an overlap detection method that
are capable of detecting a trouble in sheet feeding by determining
whether or not sheets are being conveyed while each being displaced
by a given amount from an upstream sheet in a sheet conveying
direction and overlapping the same.
SUMMARY OF THE INVENTION
[0013] According to an aspect of the present invention, there is
provided an overlap detection apparatus mounted to a printing press
in which sheets are successively conveyed while each being
displaced by a given amount from an upstream sheet in a sheet
conveying direction and overlapping the same, including: a sheet
detection sensor for detecting whether a portion of the sheets
passing a given position is a non-overlapping portion or an
overlapping portion; a signal output section for outputting an
overlapping signal on the basis of the detected results of the
sheet detection sensor, in which the overlapping signal takes a
first form for the overlapping portion and takes a second form for
the non-overlapping portion; and a determination section for
determining that the sheets are being correctly conveyed while each
being displaced by a given amount from an upstream sheet in the
conveying direction and overlapping the same when a portion of the
overlapping signal taking the first form is equal to a given
reference portion, and determines that the sheets are not being
correctly conveyed when the portion of the overlapping signal
taking the first form is not equal to the given reference
portion.
[0014] According to the overlap detection apparatus having the
above arrangement, the sheet detection sensor detects whether a
portion of the sheets passing the given position, which sheets
being successively conveyed while each being displaced from an
upstream sheet in the conveying direction and overlapping the same,
is a non-overlapping portion or an overlapping portion. Then, the
signal output section outputs an overlapping signal on the basis of
the detected result of the sheet detection sensor, in which the
overlapping signal takes the first form (e.g., an H form) for the
overlapping portion (double sheet portion) and takes the second
form (e.g., an L form) for the non-overlapping portion (single
sheet portion). Then, the overlapping signal output from the signal
output section is input to the determination section.
[0015] Then, the determination section compares the portion of the
overlapping signal taking the first form with the given reference
portion, and when both the portions are equal to each other, it
determines that the sheets are being correctly conveyed while each
being displaced by a given amount from an upstream sheet in the
conveying direction and overlapping the same, and when both are not
equal, it determines that the sheets are not being correctly
conveyed.
[0016] According to another aspect of the present invention, there
is provided an overlap detection apparatus mounted to a printing
press in which sheets are successively conveyed while each being
displaced by a given amount from an upstream sheet in a sheet
conveying direction and overlapping the same, including: a sheet
detection sensor for detecting whether a portion of the sheets
passing a given position is a non-overlapping portion or an
overlapping portion; a signal output section for outputting an
overlapping signal on the basis of the detected result of the sheet
detection sensor, in which the overlapping signal takes a first
form for the overlapping portion and takes a second form for the
non-overlapping portion; and a determination section for
determining that the sheets are being correctly conveyed while each
being displaced by a given amount from an upstream sheet in the
conveying direction and overlapping the same, when the timing, at
which the form of the overlapping signal is changed from the first
form to the second form or vice versa, relative to a printing
reference of the printing press, is equal to a given reference
timing; and determines that the sheets are not being correctly
conveyed, when the timing, at which the form of the overlapping
signal is changed from the first form to the second form or vice
versa, relative to the printing reference of the printing press, is
not equal to the given reference timing.
[0017] According to the overlap detection apparatus having the
above arrangement, the sheet detection sensor detects whether a
portion of the sheets passing the given position, which sheets
being successively conveyed while each being displaced from an
upstream sheet in the conveying direction and overlapping the same,
is a non-overlapping portion or an overlapping portion. Then, the
signal output section outputs an overlapping signal on the basis of
the detected result of the sheet detection sensor, in which the
overlapping signal takes the first form (e.g., an H form) for the
overlapping portion (double sheet portion) and takes the second
form (e.g., an L form) for the non-overlapping portion (single
sheet portion). Then, the overlapping signal output from the signal
output section is input to the determination section.
[0018] Then, the determination section compares the timing, at
which the form of the overlapping signal is changed from the first
form to the second form or vice versa, relative to the printing
reference of the printing press, with the given reference timing,
and when both the timings are equal to each other, it determines
that the sheets are being correctly conveyed while each being
displaced by a given amount from an upstream sheet in the conveying
direction and overlapping the same, and when both are not equal, it
determines that the sheets are not being correctly conveyed.
[0019] In the above overlap detection apparatus, the printing press
preferably includes a sheet feeding cylinder, and an encoder that
outputs a rotation signal with reference to the rotation of the
sheet feeding cylinder, and the rotation signal output by the
encoder is employed as the printing reference of the printing
press.
[0020] It is preferable to employ an arrangement, in which the
printing press includes a feeder board that conveys the sheets
placed thereon towards a downstream side; the sheet detection
sensor comprises a pair of upper and lower members disposed
vertically with a downstream end of the feeder board therebetween
so as to detect whether a portion of the sheets passing between the
upper and lower members of the sheet detection sensor is the
non-overlapping portion or the overlapping portion.
[0021] It is preferable that the overlapping signal takes an H form
for the overlapping sheet portion and takes an L form for the
non-overlapping portion.
[0022] It is preferable to employ an arrangement, in which the
printing press includes a feeder board that conveys the sheets
placed thereon towards a downstream side; the determination section
outputs a stop signal when it determines that the sheets are not
being correctly conveyed; and the printing press further includes a
feeder board stop device that stops the feeder board on the basis
of the stop signal.
[0023] It is preferable to employ an arrangement, in which the
printing press includes a feeder board that conveys the sheets
placed thereon towards a downstream side; and the determination
section outputs an annunciation signal when it determines that the
sheets are not being correctly conveyed; and the printing press
further includes an annunciation device that is actuated on the
basis of the annunciation signal.
[0024] The signal output section is preferably made up of an
amplifier.
[0025] According to still another aspect of the present invention,
there is provided an overlap detection method of determining
whether or not sheets are being correctly conveyed in a printing
press, in which the sheets are conveyed while each being displaced
by a given amount from an upstream sheet in a sheet conveying
direction and overlapping the same, on the basis of detection of an
overlapping state of the sheets, including: detecting whether a
portion of the sheets passing a given position is a non-overlapping
portion or an overlapping portion by a sheet detection sensor;
outputting an overlapping signal on the basis of the detected
result of the sheet detection sensor, in which the overlapping
signal takes a first form for the overlapping portion; and
determining that the sheets are being correctly conveyed while each
being displaced by a given amount from an upstream sheet in the
conveying direction and overlapping the same when a portion of the
overlapping signal taking the first form is equal to a given
reference portion, and determining that the sheets are not being
correctly conveyed when the portion of the overlapping signal
taking the first form is not equal to the given reference
portion.
[0026] According to another aspect of the present invention, there
is provided an overlap detection method of determining whether or
not sheets are being correctly conveyed in a printing press, in
which the sheets are conveyed while each being displaced by a given
amount from an upstream sheet in a sheet conveying direction and
overlapping the same, on the basis of detection of an overlapping
state of the sheets, including: detecting whether a portion of the
sheets passing a given position is a non-overlapping portion or an
overlapping portion by a sheet detection sensor; outputting an
overlapping signal on the basis of the detected result of the sheet
detection sensor, in which the overlapping signal takes a first
form for the overlapping portion and takes a second form for the
non-overlapping portion; and determining that the sheets are being
correctly conveyed while each being displaced by a given amount
from an upstream sheet in the conveying direction and overlapping
the same when the timing, at which the form of the overlapping
signal is changed from the first form to the second form or vice
versa, relative to a printing reference of the printing press, is
equal to a given reference timing, and determining that the sheets
are not being correctly conveyed when the timing, at which the form
of the overlapping signal is changed from the first form to the
second form or vice versa, relative to the printing reference of
the printing press, is not equal to the given reference timing.
[0027] According to the overlap detection apparatus and the overlap
detection method, it is possible to produce an advantage of
detecting a trouble in sheet feeding.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] The above, and other objects, features and advantages of the
present invention will become apparent from the detailed
description thereof in conjunction with the accompanying drawings
wherein.
[0029] FIG. 1 is a schematic view of a pat of a printing press
equipped with an overlap detection apparatus according to a first
embodiment of the present invention.
[0030] FIG. 2 is a flowchart illustrating a control method of the
overlap detection apparatus of the first embodiment.
[0031] FIG. 3 is a schematic view of a pat of a printing press
equipped with an overlap detection apparatus according to a second
embodiment of the present invention.
[0032] FIG. 4 is a flowchart illustrating a control method of the
overlap detection apparatus of the second embodiment.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0033] Now, the description will be made for an overlap detection
apparatus according to a first embodiment of the present invention
with reference to the drawings attached hereto.
[0034] FIG. 1 illustrates a printing press 1 equipped with an
overlap detection apparatus 2 of this embodiment. The printing
press 1 includes a printing section 3 and a conveying section 4
that conveys sheets to the printing section 3 one by one. The
conveying section 4 includes a feeder board 5 for conveying sheets
P, which are successively fed from a lifting table (not shown) and
mounted on the feeder board 5, towards a downstream side, a front
abutting member 6 for abutting with a leading edge of the oncoming
sheet P conveyed by the feeder board 5 to correct the position of
the sheet P, and a swing claw 8 for picking up the leading edge of
the sheet P whose position has been corrected and feeding the same
to a sheet feeding cylinder 7 of the printing section 3.
[0035] According to the correct operation, the sheets P fed onto
the lifting table are each displaced from the upstream sheet P in
the conveying direction by a given amount and overlaps the same on
the feeder board 5 and these sheets P are successively conveyed in
this overlapping state. In other words, in the correct conveying
operation, a preceding sheet P is placed on the feeder board 5
while being displaced from the subsequent sheet P by a given amount
in the conveying direction and overlapping the same. By the given
amount (a so-called stream pitch) is herein meant a distance
between the leading edge of the preceding sheet P and the leading
edge of the subsequent sheet P. This may be set to be about 180
mm.
[0036] The preceding sheet P conveyed on the feeder board 5 abuts
with the front abutting member 6 that in turn corrects the position
(sheet alignment) of the preceding sheet P, and the leading edge
thereof is picked up by the swing claw 8 so that it is drawn out at
a speed higher than the conveying speed. Thus, the sheets P are fed
onto the sheet feeding cylinder 7 one by one.
[0037] The overlap detection apparatus 2 mounted in the printing
press 1 includes a sheet detection sensor 9 for detecting whether a
portion of the sheets P passing a given position is a
non-overlapping portion or an overlapping portion, an amplifier 10
as a signal output section for outputting an overlapping signal on
the basis of the detected result of the sheet detection sensor 9,
and a determination section 11 for determining the conveying status
of the sheets P by the comparison between the overlapping signal
and a given reference portion, so that when the comparison
indicates a given condition, it is determined that the sheets P are
being correctly conveyed while each being displaced from the
upstream sheet P by a given amount in the conveying direction, and
when the comparison indicates otherwise, it is determined that the
sheets 1 are not being correctly conveyed.
[0038] The sheet detection sensor 9 is made up of a pair of upper
and lower members disposed around the downstream end of the feeder
board 5, and more specifically disposed vertically along the path
between the feeder board 5 and the front abutting member 6,
allowing the sheets P to pass therebetween. For the sheet detection
sensor 9, it is possible to employ a known sensor, such as a
photoelectric sensor that detects the overlapping state of the
sheets P on the basis of the difference in the intensity of light
that has been irradiated to an oncoming sheet P and passed
therethrough, and an ultrasonic sensor that detects the overlapping
state of the sheets P by irradiation of supersonic waves, on the
basis of the presence and absence of an air layer, which occurs
between the sheets P when two or more sheets P overlap each
other.
[0039] Herein, as mentioned above, in the correct conveying
operation, the sheets P are successively conveyed while each
precedent sheet being displaced from the subsequent sheet P by a
given amount, so that they successively and continuously pass
between the upper and lower members of the sheet detection sensor 9
without a gap between the preceding and subsequent sheets P. That
is, when the sheets P are being conveyed in a correct overlapping
state, non-overlapping portions (single sheet portions) and
overlapping portions (double sheet portions) alternately pass an
area between the upper and lower members of the sheet detection
sensor 9 at constant periodic intervals. Accordingly, the detected
result in the correct conveying state indicates that
non-overlapping portions (single sheet portions) and overlapping
portions (double sheet portions) alternately appear at constant
periodic intervals.
[0040] Now, the description will be made for the case where the
sheets P are being conveyed in a correct overlapping manner.
[0041] A first (leading) one of the sheets P conveyed in a correct
overlapping manner passes between the upper and lower members of
the sheet detection sensor 9 and then abuts with the front abutting
member 6, and accordingly the motion of the first sheet P in the
conveying direction is stopped. At this moment, a non-overlapping
portion (single sheet portion) of the sheets is located between the
upper and lower members of the sheet detection sensor 9. The
position of the first sheet P is thus aligned or corrected by the
front abutting member 6.
[0042] Then, the first sheet P has its leading edge gripped by a
gripper 81 of the swing claw 8, while the subsequent sheet P is
being continuously conveyed by the feeder board 5 even until the
leading edge of the first sheet P has been gripped by the gripper
81 after the motion of the first sheet P in the conveying direction
is stopped, so that the leading edge of a second (subsequent) sheet
P passes the area between the upper and lower members of the sheet
detection sensor 9. From this moment, an overlapping portion
(double sheet portion) is located between the upper and lower
members of the sheet detection sensor 9. That is, an overlapping
portion (double sheet portion) continues to exist until the tailing
edge of the first sheet P passes between the upper and lower
members of the sheet detection sensor 9 after the leading edge of
the second sheet P reaches between the upper and lower members of
the sheet detection sensor 9.
[0043] Then, the first sheet P has its leading edge gripped by the
gripper 81, drawn out at a speed higher than the conveying speed
and fed onto the sheet feeding cylinder 7. When the tailing edge of
the first sheet P drawn out passes between the upper and lower
members of the sheet detection sensor 9, the overlapping portion
(double sheet portion) ends and again a non-overlapping portion
(single sheet portion) reaches between the upper and lower members
of the sheet detection sensor 9.
[0044] Then, the second sheet P becomes a first (leading) sheet P
as the first sheet P mentioned above, and subsequently conveyed and
fed to the sheet feeding cylinder 7 in the same manner as
above.
[0045] Thus, when the sheets P are conveyed in a correct
overlapping manner, a preceding sheet P is displaced from the
subsequent sheet P by a given amount and hence overlaps the same,
so that a non-overlapping portion (single sheet portion) and an
overlapping portion (double sheet portion) alternately appear at
constant periodic intervals between the upper and lower members of
the sheet detection sensor 9. That is, the time intervals in which
the sheet detection sensor 9 detects non-overlapping sheet portions
and the time intervals in which the sheet detection sensor 9
detects overlapping sheet portions are respectively constant. Thus,
the detection in a correct conveying state results in that
overlapping portions (width) of the sheets P and non-overlapping
portions (width) of the sheets P alternately appear at constant
periodic intervals.
[0046] The amplifier 10 outputs an overlapping signal on the basis
of the detected result of the sheet detection sensor 9. The
overlapping signal takes a first form (H form) for an overlapping
portion of the sheets P, and takes a second form (L form) for a
non-overlapping portion of the sheets P. Specifically, according to
the detected result of the sheet detection sensor 9, the
overlapping signal keeps taking the first form during the sheet
detection sensor 9 detects an overlapping portion of the sheets P
and keeps taking the second form during the sheet detection sensor
9 detects a non-overlapping portion of the sheets P.
[0047] According to the detected result in a correct conveying
state, an overlapping portion (double sheet portion) and a
non-overlapping portion (single sheet portion) alternately appear
at constant periodic intervals, so that the overlapping signal
output by the amplifier 10 becomes a signal having a wave pattern
with the first form and the second form alternately and repeatedly
appearing at constant periodic intervals. In other words, the
overlapping signal in a correct conveying state resultingly has
portions each taking the first form and portions each taking the
second form, those portions alternately appearing at constant
periodic intervals. The amplifier 10 of this embodiment, along with
the determination section 11 and a memory section 12, those will be
hereinafter described, constitute a CPU, while the amplifier 10 may
be connected to an external member or part or mounted in the sheet
detection sensor 9.
[0048] The determination section 11 determines that the sheets P
are being correctly conveyed while each being displaced from the
upstream sheet P by a given amount in the conveying direction and
overlapping the same when the portion of the overlapping signal
taking the first form is equal to a given reference portion, and
determines that the sheets P are not being correctly conveyed when
it is not equal to the given reference portion.
[0049] By the given reference portion is herein meant an
overlapping portion of the sheets P when the sheets are being
correctly conveyed and, in other words, a portion of the
overlapping signal taking the first form or second form in the
sheet conveying when the sheets P are being conveyed in a correct
overlapping manner. Specifically, the given reference portion may
be represented by the time interval in which the sheet detection
sensor 9 detects a non-overlapping portion (single sheet portion)
or an overlapping portion (double sheet portion) when the sheets P,
each being conveyed while being displaced from the upstream sheet P
in the conveying direction, pass a given position (between the
upper and lower members of the sheet detection sensor 9).
Alternatively, the given reference portion may be represented by
the displaced amount of each sheet P from the upstream sheet P in
the conveying direction. This given reference portion is stored in
the memory section 12 of the CPU by, for example, manual inputting
by an operator, or automatically stored with designated as a
reference an overlapping sheet portion or non-overlapping sheet
portion of the first and second sheets P when they pass the sheet
detection sensor 9.
[0050] When a preceding sheet P is not displaced from the
subsequent sheet P by a given amount when they overlap, it is
determined that the sheets P are not being correctly conveyed. For
example, such incorrect conveyance of the sheets P represents that
the displaced amount is larger or smaller than a given amount.
[0051] The overlap detection apparatus 2 further includes a feeder
stop solenoid SOL as a feeder board stopping device for stopping
the feeder board 5 upon receiving a stop signal from the
determination section 11 when the determination section 11 has
determined that the sheets P are not being correctly conveyed, and
an annunciation lamp as an annunciation device that turns on or
blinks upon receiving an annunciation signal from the determination
section 11 when the determination section 11 has determined that
the sheets P are not being correctly conveyed. For the annunciation
lamp, an LED or the like may be used, which is designed to change
the color in addition to a turning-on action and a blinking
action.
[0052] Now, the description will be made for a control method of
the overlap detection apparatus 2 of this embodiment, with
reference to a flowchart illustrated in FIG. 2.
[0053] First, the printing press 1 is started up to print on the
sheets P. Upon the start-up, the respective members or parts such
as the swing claw 8 are actuated to be in synchronization with the
rotation of the sheet feeding cylinder 7, so that the sheets P are
fed out from the lifting table onto the feeder board 5. When the
sheets P are conveyed on the feeder board 5, the sheet detection
sensor 9 detects whether a portion of the sheets P passing the
sheet detection sensor 9 is a non-overlapping portion (single sheet
portion) or an overlapping portion (double sheet portion), and
transmits the detected result to the amplifier 10 (Step S1).
[0054] The amplifier 10 which received the detected result of the
sheet detection sensor 9 outputs an overlapping signal, which takes
the first form (H form) for an overlapping portion (double sheet
portion) and the second form (L form) for a non-overlapping portion
(single sheet portion), and transmits the same to the determination
section 11 (Step S2).
[0055] Upon receiving the overlapping signal, the determination
section 11 reads out the reference portion (in this embodiment, the
time interval in which the sheet detection sensor 9 detects an
overlapping portion (double sheet portion) passing between the
upper and lower members of the sheet detection sensor 9 in a
correct overlapping manner) stored in the memory section 12, and
compares the same with a portion of the overlapping signal taking
the first position (Step S3). When, as the reference portion, the
time interval in which the sheet detection sensor 9 detects a
non-overlapping portion (single sheet portion) passing between the
upper and lower members of the sheet detection sensor 9 in a
correct overlapping manner, that is, a portion of the overlapping
signal taking the second form, is employed, the determination
section 11 compares the portion of the overlapping signal taking
the second form with the reference portion.
[0056] Accordingly, the determination section 11 determines that
the sheets P are being correctly conveyed when both the portions
are equal to each other, and subsequently compares the portion of
the overlapping signal taking the first form with a corresponding
reference portion. When both the portions are not equal to each
other, the determination section 11 determines that the sheets P
are not being correctly conveyed (Step S4).
[0057] When it is determined that the sheets P are not being
correctly conveyed (when the portion of the overlapping signal
taking the first form is longer or shorter than the reference
portion), the determination section 11 outputs a stop signal and an
annunciation signal (Step S5, Step S6), and, upon receiving the
stop signal, the feeder stop solenoid SOL stops the conveying of
the sheets P by stopping the feeder board 5 (Step S7), and, upon
receiving the annunciation signal, the annunciation lamp turns on
or blinks to announce this stopping operation to the operator (Step
S8).
[0058] Thus, the determination section 11 compares the portion of
the overlapping signal taking the first form with the reference
portion so as to be able to determine whether the sheets are being
conveyed in a correct overlapping manner. As a result, it is
possible to detect a trouble in sheet feeding.
[0059] Now, the description will be made for a second embodiment of
the overlap detection apparatus 2 of the present invention. In this
embodiment, the same reference numerals will be allocated to the
identical or corresponding members or parts so as to omit the
detailed description thereof. The overlap detection apparatus 2 of
this embodiment includes the sheet detection sensor 9, the
amplifier 10, the determination section 11, the memory section 12
that stores a reference timing, the feeder stop solenoid SOL and
the annunciation lamp. The overlap detection apparatus 2 further
includes an encoder 13 for outputting a rotation signal as a
printing reference of the printing press 1.
[0060] The encoder 13 is to output a rotation signal as a printing
reference of the printing press 1, and specifically output a
rotation signal with reference to the rotation of the sheet feeding
cylinder 7. For example, the encoder 13 outputs a signal taking an
H form every time when the sheet feeding cylinder 7 is set at a
rotational angle of 0 degree. That is, the rotation signal is a
signal that takes the H form at constant periodic intervals on the
basis of the detected result of the rotational angle of the sheet
feeding cylinder 7.
[0061] The determination section 11 determines that the sheets are
being correctly conveyed while each being displaced from the
upstream sheet P by a given amount in the conveying direction and
overlapping the same when the timing, at which the form of an
overlapping signal is changed from the first to second forms or
vice versa, relative to the printing reference of the printing
press 1, is equal to a given reference timing, and determines that
the sheets P are not being correctly conveyed when the above timing
is not equal to the given reference timing.
[0062] By the timing at which the form of an overlapping signal is
changed between the first form and the second form is herein meant
the timing at which the form of the overlapping signal is changed
from the first form to the second form or vice versa, relative to
the rotation of the sheet feeding cylinder 7. Specifically, when
the H form of the rotation signal transmitted from the encoder 13
is employed as a reference, the timing herein meant is the timing
at which the form of the overlapping signal is changed from the
first form to the second form or vice versa.
[0063] On the other hand, as described above, when the sheets P are
being conveyed in a correct overlapping manner, a preceding sheet P
is displaced from the subsequent sheet P by a given amount and
overlaps the same, so that non-overlapping portions (single sheet
portions) and overlapping portions (double sheet portions)
alternately appear at constant periodic intervals between the upper
and lower members of the sheet detection sensor 9. Since the swing
claw 8 is generally operated in synchronization with the rotation
of the sheet feeding cylinder 7, so that the sheets P are fed one
by one in synchronization with the rotation of the sheet feeding
cylinder 7. Therefore, when the sheets P are being conveyed in a
correct overlapping manner, the timing, at which a portion of the
sheets P passing between the upper and lower members of the sheet
detection sensor 9 is changed from a non-overlapping portion
(single sheet portion) to an overlapping sheet portion (double
sheet portion), or vice versa, is shifted in synchronization with
the rotation of the sheet feeding cylinder 7.
[0064] By the given reference timing is herein meant a timing, at
which the form of the overlapping signal is changed from the first
form to the second form or vice versa, with reference to the
rotation of the sheet feeding cylinder 7 when the sheets are being
conveyed while correctly overlapping each other. Specifically, by
the given reference timing is herein meant a timing at which the
form of the overlapping signal is changed from the first form to
the second form or vice versa, with reference to the H form of the
rotation signal of the encoder 13 when the sheets P are being
conveyed while correctly overlapping each other. This given
reference timing is stored in the memory section 12 by, for
example, manual inputting by an operator, or automatically stored
with designating as a reference the timing at which the first
(leading) and second (subsequent) sheets pass.
[0065] Now, the description will be made for a control method of
the overlap detection apparatus 2 of this embodiment, with
reference to a flowchart illustrated in FIG. 4.
[0066] First, the printing press 1 is started up to print on the
sheets P. Upon the start-up, the sheet feeding cylinder 7 is
rotated, and the respective members or parts such as the swing claw
8 are actuated to be in synchronization with the rotation of the
sheet feeding cylinder 7. For example, the respective members or
parts are actuated in synchronization with the rotation of the
sheet feeding cylinder 7 so that one sheet P is fed for one
rotation of the sheet feeding cylinder 7. Thus, the sheets P are
conveyed on the feeder board 5 while the respective parts and
members are actuated in synchronization with the rotation of the
sheet feeding cylinder 7. Then, the sheet detection sensor 9
detects whether a portion of the sheets P passing between the upper
and lower members of the sheet detection sensor 9 is a
non-overlapping portion (single sheet portion) or an overlapping
portion (double sheet portion), and transmits the detected result
to the amplifier 10 (Step S11).
[0067] Upon receiving the detected result, the amplifier 10
outputs, on the basis of the detected result, an overlapping signal
that takes the first form (H form) for an overlapping portion
(double sheet portion) and the second form (L form) for a
non-overlapping portion (single sheet portion), and transmits the
same to the determination section 11 (Step S12).
[0068] On the other hand, the encoder 13 transmits a rotation
signal based on the rotational reference of the sheet feeding
cylinder 7 (Step S12).
[0069] Upon receiving the overlapping signal transmitted from the
amplifier 10 and the rotation signal transmitted from the encoder
13, the determination section 11 measures the timing at which the
form of the overlapping signal is changed from the first form to
the second form, relative to the rotation signal (Step S13). Then,
it reads out the reference timing (in this embodiment, the timing
at which the form of the overlapping signal is changed from the
first form to the second form in a correct conveying state) stored
in the memory section 12, and compares the measured timing with the
reference timing (Step S14). In a case where the timing, at which
the form of the overlapping signal is changed from the second form
to the first form, is employed as the reference timing, the
determination section 11 measures the timing at which the form of
the overlapping signal is changed from the second form to the first
form, relative to the rotation signal, and compares the same with
the reference timing.
[0070] Then, the determination section 11 determines that the
sheets P are being correctly conveyed when both the timings are
equal to each other, and then compares the subsequently measured
timing with the corresponding reference timing. On the other hand,
when both the timings are not equal to each other, it determines
that the sheets P are not being correctly conveyed (Step S15).
[0071] In a case where it has been determined that the sheets P are
not being correctly conveyed (for the reason that the measured
timing is faster or lower than the reference timing), the
determination section 11 outputs a stop signal and an annunciation
signal (Step S16, Step S17), and upon receiving the stop signal,
the feeder stop solenoid SOL stops the feeder board 5 to stop the
conveying of the sheets P (Step S18), while upon receiving the
annunciation signal, the annunciation lamp turns on or blinks to
announce this stopping operation to the operator (Step S19).
[0072] Thus, by comparing the timing, at which the form of the
overlapping signal is changed between the first form and the second
form, relative to the rotation reference of the sheet feeding
cylinder 7, with the reference timing, it is possible to determine
whether the sheets P are being conveyed in a correct overlapping
manner, and hence to detect a trouble in sheet feeding.
[0073] In the first and second embodiments, the description was
made by taking for example a case where the amplifier 10 as the
signal output section is designed to output an overlapping signal
that takes two forms, namely the first form (H form) and the second
form (L form). No limitation is intended to this, and therefore the
amplifier 10 may be designed to output an overlapping signal that
takes three forms. Specifically, the amplifier 10 may be designed
to output an overlapping signal that takes a reference form (M
form) when no sheet P is passing between the upper and lower
members of the sheet detection sensor 9; takes the first form (H
form) when the passing sheet P is a double or other multiple; and
takes the second form (L form) when the passing sheet P is a
single. Thus, it is possible to detect the state in which no sheet
P is passing between the upper and lower members of the sheet
detection sensor 9 and hence immediately find out the detail of a
trouble in sheet feeding.
[0074] This specification is by no means intended to restrict the
present invention to the preferred embodiments set forth therein.
Various modifications to the overlap detection apparatus and the
overlap detection method, as described herein, may be made by those
skilled in the art without departing from the spirit and scope of
the present invention as defined in the appended claims.
* * * * *