U.S. patent application number 12/035934 was filed with the patent office on 2008-08-28 for paper multi-feed detection apparatus and paper multi-feed detection method.
This patent application is currently assigned to Sharp Kabushiki Kaisha. Invention is credited to Hidetoshi Atsumi, Hideki CHUJO, Fuminori Miyoshi, Hitoshi Nakamura, Shinji Nakazawa, Junko Yabuta.
Application Number | 20080203654 12/035934 |
Document ID | / |
Family ID | 39714982 |
Filed Date | 2008-08-28 |
United States Patent
Application |
20080203654 |
Kind Code |
A1 |
CHUJO; Hideki ; et
al. |
August 28, 2008 |
PAPER MULTI-FEED DETECTION APPARATUS AND PAPER MULTI-FEED DETECTION
METHOD
Abstract
A paper multi-feed detection apparatus and a paper multi-feed
detection method are provided for preventing the detection
capability from being deteriorated by a noise factor and improving
the detection precision even where an area around the feeding path
has no extra space in terms of the shape and there are many
noise-generating factors because of a demand for a smaller size of
the device. An ultrasonic transmission opening formed in one of two
feeding guide plates is large so as to discharge outside a
reflected wave which returns through the ultrasonic transmission
opening, and an ultrasonic receiving opening formed in the other
feeding guide plate is smaller than a receiving face area of a
receiver for receiving the ultrasonic wave.
Inventors: |
CHUJO; Hideki; (Kyoto-shi,
JP) ; Nakamura; Hitoshi; (Kyoto-shi, JP) ;
Yabuta; Junko; (Osaka-shi, JP) ; Miyoshi;
Fuminori; (Osaka-shi, JP) ; Atsumi; Hidetoshi;
(Osaka-shi, JP) ; Nakazawa; Shinji; (Osaka-shi,
JP) |
Correspondence
Address: |
MORRISON & FOERSTER LLP
1650 TYSONS BOULEVARD, SUITE 400
MCLEAN
VA
22102
US
|
Assignee: |
Sharp Kabushiki Kaisha
Osaka-shi
JP
|
Family ID: |
39714982 |
Appl. No.: |
12/035934 |
Filed: |
February 22, 2008 |
Current U.S.
Class: |
271/262 |
Current CPC
Class: |
B65H 2511/524 20130101;
B65H 7/12 20130101; B65H 2515/82 20130101; B65H 2553/30 20130101;
B65H 2515/82 20130101; B65H 2511/524 20130101; B65H 2701/1912
20130101; B65H 2404/611 20130101; B65H 2220/01 20130101; B65H
2220/03 20130101 |
Class at
Publication: |
271/262 |
International
Class: |
B65H 7/12 20060101
B65H007/12 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 23, 2007 |
JP |
2007-43258 |
Claims
1. A paper multi-feed detection apparatus, comprising: a feeding
path covered with one feeding guide plate and another feeding guide
plate facing each other while having therebetween a feeding space
for feeding a paper sheet two-dimensionally; and a transmitter of
an ultrasonic sensor provided on one of two sides facing each other
while having the feeding space therebetween, and a receiver of the
ultrasonic sensor provided on the other of the two sides; wherein:
an ultrasonic wave is incident on the feeding space from the
transmitter via an entrance opening formed in the one feeding guide
plate; the ultrasonic wave output via an exit opening formed in the
another feeding guide plate is received by the receiver; paper
multi-feed is detected by comparing attenuation information on the
ultrasonic wave when the paper sheet passes between the transmitter
and the receiver, against a threshold value for multi-feed
detection; the entrance opening is formed to be large so as to
discharge outside the ultrasonic wave incident thereon and then
reflected, without making the reflected wave a noise component; and
the exit opening is formed to be smaller than a receiving face area
of the receiver for receiving the ultrasonic wave.
2. A paper multi-feed detection apparatus, comprising: a feeding
path covered with one feeding guide plate and another feeding guide
plate facing each other while having therebetween a feeding space
for feeding a paper sheet two-dimensionally; and a transmitter of
an ultrasonic sensor provided on one of two sides facing each other
while having the feeding space therebetween, and a receiver of the
ultrasonic sensor provided on the other of the two sides; wherein:
an ultrasonic wave is incident on the feeding space from the
transmitter via an entrance opening formed in the one feeding guide
plate; the ultrasonic wave output via an exit opening formed in the
another feeding guide plate is received by the receiver; paper
multi-feed is detected by comparing attenuation information on the
ultrasonic wave when the paper sheet passes between the transmitter
and the receiver, against a threshold value for multi-feed
detection; an ultrasonic wave transmission area from the
transmitter to the entrance opening is in a open state; and an
ultrasonic wave receiving area from the exit opening to the
receiver is enclosed by a noise shielding wall.
3. A paper multi-feed detection method, wherein where a transmitter
and a receiver are provided to face each other while having a
feeding path for a paper sheet therebetween, an entrance opening,
on which an ultrasonic wave transmitted from the transmitter toward
the receiver is incident via a feeding guide plate which covers an
ultrasonic wave transmission side of the feeding path, is formed to
be large so as to discharge a reflected wave outside; and an exit
opening, for outputting the ultrasonic wave via a feeding guide
plate which covers an ultrasonic receiving side of the feeding path
facing the ultrasonic transmission side, is formed to be smaller
than a receiving face area of the receiver.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a paper multi-feed
detection apparatus applicable to office equipment such as, for
example, copiers and scanners, and more specifically to a paper
multi-feed detection apparatus and a paper multi-feed detection
method for accurately detecting that sheets of paper such as blank
or printed forms, banknotes, gift certificates, book coupons,
checks, cards and the like are fed in an overlapped state.
[0003] 2. Description of the Prior Art
[0004] Recently, as an apparatus for detecting multi-feed of sheets
of paper which easily tend to be fed in an overlapped state, for
example, sheets of thin paper or the like, a paper multi-feed
detection apparatus using an ultrasonic sensor is known. When such
an ultrasonic sensor is used to detect sheets of paper, the
following detection capabilities unique to the ultrasonic sensor
are provided.
[0005] (1) Since detection is performed without any contact with
the paper sheets, feeding of the paper sheets is not disturbed.
[0006] (2) Since detection can be performed regardless of the
thickness of the paper sheet, multi-feed can be detected even where
paper sheets having different thicknesses are present.
[0007] (3) Since detection can be performed regardless of the color
of the paper sheet, no adjustment is necessary for different colors
of the paper sheets.
[0008] FIG. 4 shows an example of such a paper multi-feed detection
apparatus using an ultrasonic sensor having the above-described
features. The paper multi-feed detection apparatus shown in FIG. 4
has the following structure. A feeding path 42 for feeding a paper
sheet 41 two-dimensionally is interposed between a transmitter 44
of an ultrasonic sensor 43 and a receiver 45 of the ultrasonic
sensor 43. The transmitter 44 is provided above the feeding path
42, and the receiver 45 is provided below the feeding path 42. The
transmitter 44 and the receiver 45 face each other. Transmitting
and receiving directions of the transmitter 44 and the receiver 45
are set to be oblique with respect to the feeding path 42.
[0009] An ultrasonic wave 46 which is transmitted from the
transmitter 44 is directed to a top surface of the paper sheet 41
via an entrance opening 48 for transmitting the ultrasonic wave.
The entrance opening 48 is formed in an upper feeding guide plate
47 which covers a top surface of the feeding path 42. The
ultrasonic wave 46 directed to the paper sheet 41 is transmitted
through the paper sheet 41 and is received by the receiver 45 via
an exit opening 50 for transmitting the ultrasonic wave. The exit
opening 50 is formed in a lower feeding guide plate 49 which covers
a bottom surface of the feeding path 42, and has the same size as
that of the entrance opening 48. The attenuation amount
(transmission amount) of the ultrasonic wave 46 caused by the
transmission through the paper sheet 41 is measured, and thus a
control section detects whether one paper sheet 41 is being fed or
a plurality of paper sheets are being fed in an overlapped state
(see, for example, Patent Document 1).
[0010] However, there may be an occasion that when the ultrasonic
wave 46 is directed to the paper sheet 41, a part of the ultrasonic
wave 46 is reflected by a top face of the paper sheet 46 and the
reflected wave is reflected diffusedly in a feeding space 42a. For
example, the paper sheet 41 may be bent in the feeding space 42a.
When being directed to the bent paper sheet 41, the ultrasonic wave
46 is reflected diffusedly. The reflected wave generated as a
result of the diffused reflection may occasionally be received by
the receiver 45 as a noise component. Such a noise component may
deteriorate the capability of the sensor and thus cause erroneous
detection of the paper sheet 41.
[0011] In an attempt to solve this problem, the technology of
Patent Document 1 directs the ultrasonic wave toward the face of
the paper sheet obliquely so as to reduce the reflection of the
ultrasonic wave by the top face of the paper sheet and also so as
to reduce the reflection of the ultrasonic wave by a receiving face
of the receiver. However, merely setting the transmitting direction
of the ultrasonic wave to be oblique is not sufficient to obtain a
sufficient sensor capability.
[0012] In addition, devices such as copiers are desired to be
reduced in size. Therefore, there is no extra space around the
feeding path, which causes many factors generating noise
components. FIG. 5 shows another example of a paper multi-feed
detection apparatus. This paper multi-feed detection apparatus has
a structure in which a feeding path 52 for feeding a paper sheet 51
two-dimensionally is interposed between a transmitter 53 provided
above the feeding path 52 and a receiver 56 provided below the
feeding path 52. Where there is a component surrounding the feeding
path (reflecting object) 55 in or around a transmission section
from the transmitter 53 to an upper feeding guide plate 54, the
transmission wave reflected by the paper sheet 51 may hit the
component surrounding the feeding path 55 to be reflected diffusely
and the resultant wave may be received by the receiver 56 as a
noise component.
[0013] For example, where an ultrasonic sensor and an optical
sensor are both provided, a sensor opening 58 for the optical
sensor may be formed in the upper feeding guide plate 54 or a lower
feeding guide plate 57. In such a case, before the paper sheet 51
which is being fed reaches the sensor opening 58, a transmission
wave 59 transmitted through the sensor opening 58 may directly
reach the receiver 56 and may be added to the received component.
Also, a reflected wave 60 may occasionally reach the receiver 56
from a space in the vicinity of the receiver 56 and act as a noise
component. Such a noise component is likely to have an adverse
influence on the performance of the paper multi-feed detection
apparatus.
[0014] According to another known multi-feed detection apparatus, a
transmission area and a receiving area of an ultrasonic wave from
the transmitter to the receiver are enclosed by a sound-absorbing
material to absorb an external noise component and a noise
component generated by the reflected wave (see, for example, Patent
Document 2).
[0015] However, such a structure requires the transmission and
receiving areas to be enclosed air-tightly by the sound-absorbing
material, and thus decreases the level of designing freedom because
the arrangement and the shape of the sound-absorbing material are
specified. This structure also has a problem that the ultrasonic
sensor itself is costly.
[0016] Patent Document 1: Japanese Laid-Open Patent Publication No.
6-72591
[0017] Patent Document 2: Japanese Laid-Open Patent Publication No.
2005-82350
[0018] In light of the above, the present invention has an object
of providing a paper multi-feed detection apparatus and a paper
multi-feed detection method capable of properly eliminating the
reflected ultrasonic wave, which would otherwise become a noise
component, to prevent the detection capability from being
deteriorated by the noise component and thus to improve the
detection precision.
SUMMARY OF THE INVENTION
[0019] The present invention is directed to a paper multi-feed
detection apparatus comprising a feeding path covered with one
feeding guide plate and another feeding guide plate facing each
other while having therebetween a feeding space for feeding a paper
sheet two-dimensionally; and a transmitter of an ultrasonic sensor
provided on one of two sides facing each other while having the
feeding space therebetween, and a receiver of the ultrasonic sensor
provided on the other of the two sides. An ultrasonic wave is
incident on the feeding space from the transmitter via an entrance
opening formed in the one feeding guide plate; the ultrasonic wave
output via an exit opening formed in the another feeding guide
plate is received by the receiver; paper multi-feed is detected by
comparing attenuation information on the ultrasonic wave when the
paper sheet passes between the transmitter and the receiver,
against a threshold value for multi-feed detection; the entrance
opening is formed to be large so as to discharge outside the
ultrasonic wave incident thereon and then reflected, without making
the reflected wave a noise component; and the exit opening is
formed to be smaller than a receiving face area of the receiver for
receiving the ultrasonic wave.
[0020] In one embodiment of the present invention, the paper
multi-feed detection apparatus comprises a feeding path covered
with one feeding guide plate and another feeding guide plate facing
each other while having therebetween a feeding space for feeding a
paper sheet two-dimensionally; and a transmitter of an ultrasonic
sensor provided on one of two sides facing each other while having
the feeding space therebetween, and a receiver of the ultrasonic
sensor provided on the other of the two sides. An ultrasonic wave
is incident on the feeding space from the transmitter via an
entrance opening formed in the one feeding guide plate; the
ultrasonic wave output via an exit opening formed in the another
feeding guide plate is received by the receiver; paper multi-feed
is detected by comparing attenuation information on the ultrasonic
wave when the paper sheet passes between the transmitter and the
receiver, against a threshold value for multi-feed detection; an
ultrasonic wave transmission area from the transmitter to the
entrance opening is in a open state; and an ultrasonic wave
receiving area from the exit opening to the receiver is enclosed by
a noise shielding wall.
[0021] In one embodiment of the present invention, according to a
paper multi-feed detection method, where a transmitter and a
receiver are provided to face each other while having a feeding
path for a paper sheet therebetween, an entrance opening, on which
an ultrasonic wave transmitted from the transmitter toward the
receiver is incident via a feeding guide plate which covers an
ultrasonic wave transmission side of the feeding path, is formed to
be large so as to discharge a reflected wave outside; and an exit
opening, for outputting the ultrasonic wave via a feeding guide
plate which covers an ultrasonic receiving side of the feeding path
facing the ultrasonic transmission side, is formed to be smaller
than a receiving face area of the receiver.
[0022] According to the present invention, a stable transmission
capability is guaranteed because a noise component is avoided from
being generated at the time of the ultrasonic wave transmission,
and a receiving capability can be improved by properly blocking a
noise component which is likely to enter the receiver at the time
of the ultrasonic wave receiving. Especially, the structure of the
present invention does not require any new parts, and can be easily
obtained even where there is no ample extra space around the
feeding path.
BRIEF DESCRIPTION OF DRAWINGS
[0023] FIG. 1 is an operation illustration showing a detection
state of a paper multi-feed detection apparatus according to
Embodiment 1.
[0024] FIG. 2 is a block diagram of a control circuit of an
ultrasonic sensor which may be incorporated into the paper
multi-feed detection apparatus according to Embodiment 1.
[0025] FIG. 3 is an operation illustration showing a detection
state of a paper multi-feed detection apparatus according to
Embodiment 2.
[0026] FIG. 4 is an operation illustration showing a detection
state of a conventional paper multi-feed detection apparatus.
[0027] FIG. 5 is an operation illustration showing a detection
state of another conventional paper multi-feed detection
apparatus.
DESCRIPTION OF THE REFERENCE NUMERALS
[0028] 11, 31 Paper multi-feed detection apparatus [0029] 13, 33
Feeding path [0030] 14, 15, 34, 35 Feeding guide plate [0031] 16,
36 Ultrasonic sensor [0032] 17, 37 Transmitter [0033] 18, 38
Receiver [0034] 19, 39 Entrance opening [0035] 20, 40 Exit opening
[0036] 34a, Noise shielding wall [0037] U Ultrasonic wave [0038] R
Reflected wave
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Embodiment 1
[0039] Hereinafter, one embodiment of the present invention will be
described with reference to the figures.
[0040] The figures show a paper sheet multi-feed detection
apparatus which maybe built in a copier. As shown in FIG. 1, a
paper sheet multi-feed detection apparatus 11 includes a main body
12 and a feeding path 13, provided above the main body 12, for
feeding a paper sheet P in a horizontal direction
two-dimensionally. A top surface of the feeding path 13 is covered
with an upper feeding guide plate 14, and a bottom surface of the
feeding path 13 is covered with a lower feeding guide plate 15. The
upper feeding guide plate 14 and the lower feeding guide plate 15
face each other while having a two-dimensional feeding space 13a
therebetween.
[0041] A transmitter 17 of an ultrasonic sensor 16 is provided
above the feeding path 13, and a receiver 18 of the ultrasonic
sensor 16 is provided below the feeding path 13. The transmitter 17
and the receiver 18 also face each other while having the feeding
path 13 therebetween. Transmitting and receiving directions of the
ultrasonic sensor 16 are set to be oblique with respect to the
feeding path 13, so as to be suitable to transmit and receive an
ultrasonic wave U.
[0042] An entrance opening 19 is formed in the upper feeding guide
plate 14, more specifically at a position where the upper feeding
guide plate 14 crosses the transmission wave advancing in the
transmitting direction from the transmitter 17. The ultrasonic wave
U incident on the feeding space 13a from the transmitter 17 is
reflected by the paper sheet P to become a reflected wave R, which
could act as a noise component. The entrance opening 19 is formed
to be large so as to discharge the reflected wave R outside the
paper multi-feed detection apparatus 11. For example, the entrance
opening 19 may have a size sufficiently large to avoid multiple
reflections. Herein, "multiple reflections" means that when the
ultrasonic wave U is directed to a top surface of the paper sheet
P, the reflected wave R directed upward at a certain angle hits the
upper feeding guide plate 14 and is reflected again downward. The
entrance opening 19 is circular around the center of the
transmission area of the ultrasonic wave U from the transmitter 17
and has the largest possible size that does not disturb the feeding
capability.
[0043] An exit opening 20 is formed in the lower feeding guide
plate 15, more specifically at a position where the lower feeding
guide plate 15 crosses the receiving wave advancing in the
receiving direction toward the receiver 18. The exit opening 20 is
formed to be smaller than the size of a receiving face (receiving
sensor head) 18a of the receiver 18 for receiving the ultrasonic
wave U, which is output from the feeding space 13a toward the
receiver 18. The exit opening 20 is thus small so as to restrict
the area through which the ultrasonic wave U passes to a certain
size. This makes it difficult for noise to enter the receiving face
18a, and the ultrasonic wave U is received by the receiver 18
stably. Preferably, the size of the exit opening 20 is equal to or
smaller than the size of the receiving face 18a of the receiver 18
so as to prevent the noise from entering the receiver 18, or is
larger than half of the size of the receiving face 18a so as to
maintain the receiving capability.
[0044] FIG. 2 is a block diagram of a control circuit of the
ultrasonic sensor 16 which may be incorporated into the paper
multi-feed detection apparatus 11. The ultrasonic sensor 16
includes, on the transmission side, an oscillation circuit 21 for
generating a signal of a predetermined frequency (for example, 220
kHz) and an amplification circuit 22 for amplifying the signal of
the predetermined frequency.
[0045] The ultrasonic sensor 16 includes, on the receiving side, a
filter/amplification circuit 23 for removing noise and amplifying
the received signal, a rectification circuit 24 for detecting the
amplified signal, and a determination circuit 25 for comparing the
received signal against a reference value for determination.
[0046] An electric signal of a predetermined frequency which is
output from the oscillation circuit 21 is amplified by the
amplification circuit 22 to a predetermined value, is input to the
transmitter 17, and is converted into an ultrasonic wave U by a
piezoelectric element in the transmitter 17. The resultant
ultrasonic wave U is radiated toward the receiver 18 through the
paper sheet P which is fed on the feeding path 13. The ultrasonic
wave U radiated from the transmitter 17 hits the paper sheet P
which is being fed on the feeding path 13, and is partially
reflected. The ultrasonic wave U which is transmitted through the
paper sheet P is received by the receiver 18, is converted into an
electric signal by a piezoelectric element in the receiver 18, and
is input to the control circuit on the receiving side. The
attenuation degree of the ultrasonic wave U varies depending on
whether one paper sheet P is being fed or a plurality of paper
sheets P are being fed. The determination circuit 25 compares the
transmission amount (attenuation degree) of the ultrasonic wave U
against a reference value (threshold value) to detect whether the
multi-feed of the paper sheets P is occurring or not. The detection
result is transmitted to an upper-stage control section of the
device, such as a copier or the like, which incorporates the paper
multi-feed detection apparatus 11.
[0047] Now, with reference to the operation illustration in FIG. 1,
the detection state of the paper multi-feed detection apparatus 11
will be described.
[0048] The transmitter 17 of the ultrasonic sensor 16 directs the
ultrasonic wave U in the obliquely downward transmitting direction.
The ultrasonic wave U thus directed is incident on the feeding
space 13a of the feeding path 13 via the entrance opening 19 formed
in the upper feeding guide plate 14. The ultrasonic wave U is
directed toward the paper sheet P passing through the feeding space
13a. At this point, a part of the ultrasonic wave U is reflected by
the top surface of the paper sheet P, but goes outside as a
reflected wave without hitting the upper feeding guide plate 14
owing to the large entrance opening 19. Thus, the reflected wave
does not cause multiple reflections and therefore does not become a
noise factor.
[0049] Meanwhile, the ultrasonic wave which advances linearly in
the transmitting direction and is transmitted through the paper
sheet P is received by the receiver 18 while being restricted in
the amount by the small exit opening 20 facing the transmitting
direction. The exit opening 20 is small so as to restrict the
transmission amount of the ultrasonic wave U to a level appropriate
for receiving. Therefore, noise is unlikely to enter the receiver
18, and an appropriate amount of the ultrasonic wave U is received
by the receiver 18 stably.
[0050] Based on the determination result on the received ultrasonic
wave U, it is detected on the receiving side whether one paper
sheet P is being fed or a plurality of paper sheets P are being
fed. When it is determined that one paper sheet P is being fed,
normal feeding is confirmed. When it is determined that a plurality
of paper sheets P are being fed, it is found that abnormal feeding
has occurred and error information is output.
[0051] As described above, when the ultrasonic sensor 16 is used
for the paper multi-feed detection apparatus 11, the reflected wave
which would otherwise act as a noise component can be discharged
outside by simply forming the entrance opening 19 for the
ultrasonic wave U to be large. By simply forming the exit opening,
for the ultrasonic wave U to be received, to be small, the noise
can be prevented from entering the receiver 18 and the receiving
capability can be improved. The capabilities of the ultrasonic wave
can be significantly improved by simply changing the sizes of the
entrance opening 19 and the exit opening 20.
Embodiment 2
[0052] FIG. 3 shows another paper multi-feed detection apparatus
31. The paper sheet multi-feed detection apparatus 31 includes a
main body 32 and a feeding path 33, provided above the main body
32, for feeding a paper sheet P in a horizontal direction
two-dimensionally. A top surface of the feeding path 33 is covered
with an upper feeding guide plate 34, and a bottom surface of the
feeding path 33 is covered with a lower feeding guide plate 35. The
upper feeding guide plate 34 and the lower feeding guide plate 35
face each other while having a two-dimensional feeding space 33a
therebetween.
[0053] A transmitter 37 of an ultrasonic sensor 36 is provided
above the feeding path 33, and a receiver 38 of the ultrasonic
sensor 36 is provided below the feeding path 33. The transmitter 37
and the receiver 38 also face each other while having the feeding
path 33 therebetween. Transmitting and receiving directions of the
ultrasonic sensor 36 are set to be oblique with respect to the
feeding path 33, so as to be suitable to transmit and receive an
ultrasonic wave U.
[0054] An entrance opening 39 is formed in the upper feeding guide
plate 34, more specifically at a position where the upper feeding
guide plate 34 crosses the transmission wave advancing in the
transmitting direction from the transmitter 37. The ultrasonic wave
transmission area from the transmitter 37 to the entrance opening
39 is in an open state without being enclosed. Since the ultrasonic
wave transmission area is in an open state, when the ultrasonic
wave U incident on the feeding space 33a from the transmitter 37 is
reflected by the paper sheet P, the reflected wave R which would
otherwise act as a noise component is discharged outside through
the open area. Therefore, the multiple reflections in the
transmission area can be avoided. An exit opening 40 is formed in
the lower feeding guide plate 35, more specifically at apposition
where the lower feeding guide plate 35 crosses the receiving wave
advancing in the receiving direction toward the receiver 38. The
ultrasonic wave receiving area from the exit opening 40 to the
receiver 38 is enclosed by a cylindrical noise shielding wall 38a.
This structure prevents external disturbing noise R1 or the
reflected wave R from reaching the receiver 38. This makes it
difficult for noise to enter the receiver 38, and the ultrasonic
wave U is received by the receiver 18 stably.
[0055] The elements of the above-described embodiments correspond
to elements of the following claims as follows.
[0056] The paper multi-feed detection apparatus according to the
present invention corresponds to the paper multi-feed detection
apparatuses 11 and 31 in the embodiments;
[0057] the paper sheet corresponds to the paper sheet P;
[0058] one feeding guide plate corresponds to the upper feeding
guide plate 14;
[0059] another feeding guide plate corresponds to the lower feeding
guide plate 15.
[0060] The present invention is not limited to the above-described
embodiments, and may be applied in various ways based on the
technological idea defined by the claims.
* * * * *