JP2018203484A - Sheet conveyance device and image reading apparatus - Google Patents

Abstract

To provide a sheet conveyance device incorporating ultrasonic-based multi-feeding detection means capable of inhibiting displeasure from being given to an apparatus operator by stopping transmission of an ultrasonic wave during stop of conveyance.SOLUTION: A sheet conveyance device comprises: a multi-feeding determination part that determines whether or not a plurality of sheets are fed overlapped in a conveyance passage on the basis of an ultrasonic wave reception signal; a conveyance control part that controls conveyance and stop of sheets; and a sound wave transmission control part that controls a sound wave transmission part to stop transmission of the ultrasonic wave in response to stop of conveyance of a sheet in a state that the sheet is passing through between the sound wave transmission part and a sound wave reception part, wherein transmission of the ultrasonic wave is stopped during stop of conveyance of a sheet in a state that the sheet is passing through between the sound wave transmission part and the sound wave reception part, and whether or not the sheet is under conveyance is determined based on information from the conveyance control part or a conveying sound in an audible region acquired from the sound wave reception part.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a sheet conveying apparatus having a function of detecting sheet overlap (sheet double feeding) using ultrasonic waves, and an image reading apparatus including the sheet conveying apparatus.

  In a sheet conveying apparatus applied to a scanner, a printer, a copying machine, a printing machine, an ATM (Automated Teller Machine), and the like, a plurality of sheets are continuously conveyed. Feed into the device. In recent years, development of a sheet conveying apparatus in which a double feeding detection function using ultrasonic waves is added to the sheet feeding apparatus to improve the reliability of conveyance has been advanced.

  In the technique of Patent Document 1, a sheet conveying apparatus capable of performing double feed detection in a state where a sheet being conveyed is temporarily stopped has been proposed. Accordingly, by detecting whether or not the sheet that has been stopped is double-fed, it is possible to accurately detect the overlap of the sheets, and it is possible to improve the detection accuracy of the double-fed.

  In the technique of Patent Document 2, a sheet conveying apparatus that detects the presence or absence of a sheet using ultrasonic double feed detection has been proposed. As a result, it is possible to reduce the number of oscillation pulses by suppressing the transmission of excessive ultrasonic waves in a state of detecting the presence or absence of a sheet, that is, a section called a sheet interval between the sheets and the next sheet. Become.

  In the technique of Patent Document 3, an ultrasonic detection device that transmits a plurality of ultrasonic waves at different transmission intervals has been proposed. By changing the period of burst transmission in the ultrasonic burst transmission method, the user can It is possible to make it difficult to hear sound waves in the audible range.

Japanese Patent No. 424284 Japanese Patent No. 4659546 JP 2012-148873 A

  Here, in the conventional double feed detection device, there is a problem that noise transmitted to the outside of the device due to transmission of ultrasonic waves cannot be sufficiently reduced.

  The present invention provides a sheet conveying apparatus and an image reading apparatus that can effectively reduce noise caused by ultrasonic double feed detection.

  The sheet conveying apparatus of the present invention includes a conveying unit that conveys a sheet along a conveying path, a conveyance control unit that controls start and stop of sheet conveyance by the conveying unit, and an ultrasonic method of the sheet in the conveying path. A double feed detection unit for detecting double feed, and a double feed detection control unit for controlling ultrasonic transmission in the double feed detection unit, wherein the double feed detection control unit performs sheet conveyance by the conveyance control unit. Based on the stop control, control is performed so as to stop the ultrasonic transmission in the double feed detector.

  Also, the sheet conveying apparatus of the present invention is provided in the sheet conveying path, and is provided opposite to the sound wave transmitting unit that sandwiches the conveying path and a sound wave transmitting unit that transmits ultrasonic waves, and according to the received sound wave A sound wave receiving unit that outputs a received signal, an ultrasonic wave reception signal generating unit that generates an ultrasonic wave reception signal by amplifying a signal of an ultrasonic band frequency from the signal output from the sound wave receiving unit, and the ultrasonic wave A multi-feed determining unit that determines whether or not a plurality of sheets are conveyed in the conveying path based on a received signal, a conveyance control unit that controls conveyance and stop of the sheet, and a sheet that is the sound wave transmitting unit and the sheet A sound wave transmission control unit that controls the sound wave transmission unit to stop the transmission of the ultrasonic wave in response to the stop of the conveyance of the sheet in a state of passing between the sound wave reception units.

  According to the present invention, it is possible to realize a sheet conveying apparatus and an image reading apparatus that can effectively reduce noise caused by ultrasonic double feed detection. For example, regardless of the presence or absence of a sheet between the ultrasonic wave transmission unit and the ultrasonic wave reception unit, when the conveyance of the sheet is stopped, the transmission of the ultrasonic wave is stopped, thereby causing the operator to feel unpleasant sound due to the ultrasonic wave. We can provide products that do not give

An original reading apparatus having a function of detecting an overlap of sheets using ultrasonic waves. The block diagram of a double feed detection apparatus. Sectional drawing of a multifeed detector. 6 is a flowchart showing ultrasonic transmission control of the document reading apparatus. The block diagram of the modification of a double feed detection apparatus. 9 is a flowchart showing ultrasonic transmission control of a modification of the document reading apparatus. 7 is a flowchart showing ultrasonic control of the document reading apparatus according to the embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

Example 1
FIG. 1 is a cross-sectional view schematically showing a document reading apparatus having a function of detecting overlap of sheets using ultrasonic waves as a sheet conveying apparatus according to an embodiment of the present invention.

  Here, the sheet conveying apparatus according to the present embodiment is an original conveying apparatus that conveys a sheet-like original F, but instead of the original F, a recording material (sheet) on which an image is not formed is used as an image forming apparatus. It can also be used as a recording material conveying device for conveying to an image forming means. Further, the document conveying device may be provided not in the apparatus main body of the document reading apparatus but in the apparatus main body of the document post-processing apparatus that binds the document F or opens a hole.

  In FIG. 1, a document reading apparatus 100 is configured to feed a document table 1 on which a document F, which is a sheet before being conveyed, and a document F placed on the document table 1 are fed into the device one by one. A pickup roller 2 as a rotating body and a retard roller 3 as a separating rotating body for preventing a plurality of sheets from entering.

  The document F passes through the pick roller 2 and the retard roller 3 and is conveyed separately one by one. The retard roller 3 may be a separation pad instead of a roller-shaped separation rotating body.

  After the document F is fed into the apparatus, the document F passes between the sound wave transmitting unit 4a and the sound wave receiving unit 4b for detecting the overlap of the documents using ultrasonic waves. That is, the sound wave transmission unit 4a and the sound wave reception unit 4b constitute an ultrasonic wave detection unit (sensor).

  Further, the document reading apparatus 100 includes conveyance roller pairs 5a and 5b and conveyance roller pairs 7a and 7b. Further, the document reading apparatus 100 includes image reading sensors 6a and 6b on the front side and the back side of the document F.

  The image reading sensors 6a and 6b respectively read image information on the front side and the back side of the document F being conveyed and output image signals. Based on the output image signal, image data is generated by an image processing unit (not shown). The scanning interval of the image reading sensors 6a and 6b is set according to the reading speed and resolution of the document F.

The document F discharged from the document reading apparatus 100 is stacked on the discharge stacking unit 8.
In FIG. 2, reference numeral 101 denotes a double feed detection device for detecting the overlap of documents using ultrasonic waves. The double feed detection device 101 includes a control unit 102, a sound wave transmission unit 4a, and a sound wave reception unit 4b.

  The control unit 102 includes a CPU 102A, a ROM 102B, and a RAM 102C. The CPU 102A reads the program from the ROM 102B, and controls the double feed detection device 101 using the RAM 102C as a work area. Further, the CPU 102A controls the start or stop of the transmission of the sound wave transmission unit 4a via the ultrasonic wave transmission circuit (ultrasonic wave transmission control unit) 102D. In addition, the CPU 102A performs a calculation using the calculation unit 102F based on the reception result of the ultrasonic wave reception circuit 102E, and determines whether or not the document is double-fed. Further, the CPU 102A controls the transport unit 105 via the transport drive circuit 102G.

  The sound wave transmission unit 4a and the sound wave reception unit 4b will be described. The sound wave transmission unit 4a is an ultrasonic wave transmitter, and transmits ultrasonic waves to a document (sheet-like member) in the conveyance path. The sound wave receiving unit 4b is an ultrasonic receiver, and receives the ultrasonic waves transmitted from the sound wave transmitting unit 4a. The ultrasonic reception result (ultrasonic reception signal) by the acoustic wave receiving unit 4b is output to the ultrasonic reception circuit 102E and is subjected to signal processing by the ultrasonic reception circuit 102E.

  As shown in the cross-sectional view of the double feed detection device in FIG. 3, the sound wave receiving unit 4b sandwiches the original conveyance path 202 so as to receive the ultrasonic wave transmitted through the original that is the double feed detection target. It is installed so as to face the transmitter 4a. That is, the sound wave transmission unit 4 a is installed on one side of the conveyance path of the original 201 and transmits ultrasonic waves in the direction of the original 201. The sound wave receiving unit 4b is installed on the other side of the conveyance path of the original 201, receives the ultrasonic wave transmitted by the sound wave transmitting unit 4a, and outputs the ultrasonic wave reception signal to the ultrasonic wave receiving circuit 102E.

  The sound wave transmission unit 4a receives a pulse signal (hereinafter referred to as an ultrasonic signal) of several tens to several hundreds kHz from the ultrasonic wave transmission circuit 102D and outputs an ultrasonic pulse. Note that the ultrasonic signal supplied to the sound wave transmitting unit 4a by the ultrasonic wave transmitting circuit 102D is, for example, a signal for transmitting a pulse signal of several tens kHz to several hundreds kHz corresponding to several cycles over a predetermined time. This is a method generally called burst transmission, and an ultrasonic pulse is transmitted in bursts every several hundred μSec.

  FIG. 3 shows a cross-sectional view of the double feed detection device. 201 indicates a document, and 202 indicates a wall of the conveyance path. Here, when the conveyed document 201 enters between the sound wave transmission unit 4a and the sound wave reception unit 4b, the ultrasonic wave transmitted from the sound wave transmission unit 4a is attenuated by the document 201 before reaching the sound wave reception unit 4b. Since the signal is very weak, the amplitude of the ultrasonic reception signal output from the sound wave receiving unit 4b is also weak.

  In order to receive a weak signal, the ultrasonic receiving circuit 102E includes a signal amplifying circuit 110 that amplifies the ultrasonic reception signal output from the sound wave receiving unit 4b, and the ultrasonic reception signal can be determined to detect double feed. Amplifies to signal amplitude.

  The ultrasonic reception circuit 102E has an A-D converter 111, samples the ultrasonic reception signal (analog signal) amplified by the signal amplification circuit 110, converts it into a digital signal, and outputs it to the CPU 102A. In the case where the CPU 102A has a built-in A / D converter, the ultrasonic wave reception signal (analog signal) amplified by the signal amplification circuit 110 is directly input to the CPU 102A.

  The CPU 102A acquires the ultrasonic reception signal output from the ultrasonic reception circuit 102E, and stores it in the work area RAM 102C as amplitude information of the ultrasonic reception signal. Then, the CPU 102A performs calculation using the calculation unit 102F based on the amplitude information held in the work area RAM 102C, and determines whether or not the document 201 is double-fed.

  The conveyance drive circuit 102G is a circuit for conveying a sheet, and shows a motor drive circuit, various sheet detection sensors arranged in a conveyance path, and the like. The CPU 102A directly controls the transport driving circuit 102G, but may include a transport control CPU that is a slave of the CPU 102A when the scale of the apparatus is large.

  The conveyance drive circuit 102G can drive and stop the sheet at a speed corresponding to a preset condition by driving the conveyance unit 105 including a motor, a roller, and the like, and under the control of the CPU 102A.

  The situation where the conveyance of the sheet is stopped is a shortage of image reading processing capability accompanying the conveyance of the sheet, a shortage of processing capability of the device connected to the apparatus, or a sheet conveyance stop command from the apparatus operator. , Etc., and is not related to the presence or absence of a sheet between the sound wave transmitting unit 4a and the sound wave receiving unit 4b.

  The CPU 102A controls to transmit ultrasonic waves from the sound wave transmission unit 4a via the ultrasonic wave transmission circuit 102D while outputting a conveyance command to the conveyance drive circuit 102G and conveying the sheet.

  The CPU 102A outputs an ultrasonic wave from the sound wave transmitting unit 4a to the conveyance drive circuit 102G regardless of the presence or absence of the sheet between the sound wave transmitting unit 4a and the sound wave receiving unit 4b while stopping the conveyance of the sheet. Control not to send. It should be noted that the ultrasonic transmission from the ultrasonic transmission unit 4a is resumed when the sheet conveyance is resumed.

  Alternatively, while the CPU 102A issues a stop command to the conveyance drive circuit 102G and stops the conveyance of the sheet, the CPU 102A may control the ultrasonic wave transmission unit 4a to transmit the ultrasonic wave so that it cannot be heard in the human audible range. good. For example, if ultrasonic waves are transmitted in bursts at regular intervals rather than stationary, if the burst transmission time interval is 500 μs, the frequency will be 2 kHz, and from 20 Hz, which is the human audible range Although it can be heard because it enters 20 kHz, if the burst transmission time interval is increased to 100 milliseconds while the sheet conveyance is stopped, the frequency becomes 10 Hz and the sound cannot be heard. Alternatively, the burst transmission time interval may be shortened.

  FIG. 4 is a flowchart showing ultrasonic control of the document reading apparatus according to the embodiment of the present invention.

  The flow of ultrasonic control starting from step S401 of ultrasonic transmission control will be described with reference to FIG.

  When the sheet conveyance start step S402 is executed by the apparatus operator, the CPU as the control unit of the apparatus determines whether or not the sheet is being conveyed in step S403.

  If it is determined in step S403 that the sheet is being conveyed, an ultrasonic transmission process is executed in step S404, an ultrasonic reception process is executed in step S405, and an ultrasonic reception signal is also received in step S406. In addition, the double feed of the sheet is detected. Thereafter, in step S407, it is determined whether or not the sheet conveyance is finished. If it is not the end of sheet conveyance, the process returns to the determination in step S403 as to whether or not the sheet is being conveyed.

  If it is determined in step S403 that the sheet is not being conveyed, an ultrasonic stop process is executed in step S408, and it is determined in step S407 whether or not the sheet conveyance is completed. If it is not the end of sheet conveyance, the process returns to the determination in step S403 as to whether or not the sheet is being conveyed.

  The situation where the sheet is not being transported even though the sheet has started to be transported is, for example, when the product is warming up, waiting for the operator to install the sheet, It is assumed that the print data is waiting to be transferred.

  If it is determined in step S407 that the sheet conveyance has been completed, an ultrasonic stop process is executed in step S409, and the process ends in step S410.

  FIG. 7 is a flowchart showing ultrasonic control of the document reading apparatus according to the embodiment of the present invention.

  The flowchart in FIG. 7 explains ultrasonic control starting from step S701 of ultrasonic transmission control, assuming a scanner that is connected to a PC and is an input device for reading a sheet image.

  When the apparatus operator instructs the scan start S702 and executes the sheet conveyance drive start step S703, the CPU as the control unit of the apparatus determines an empty area of the image memory inside the scanner in step S704. If there is an empty area in the image memory, the scanned image can be taken in. Therefore, the process proceeds to the next step, and whether or not data transfer to the PC is possible is determined in S705.

  If it is determined in step S705 that data transfer to the PC is possible, ultrasonic transmission processing is executed in step S706, ultrasonic reception processing is executed in step S707, and ultrasonic transmission processing is executed in step S708. Based on the received signal, double sheet feeding is detected. Thereafter, in step S709, it is determined whether or not the sheet conveyance is finished. If it is not the end of the sheet conveyance, the process returns to the determination of the free area of the image memory in step S704 while continuing the sheet conveyance.

  If it is determined in step S704 that there is no free space in the image memory, or if it is determined in step S705 that data transfer to the PC is not possible, the sheet conveyance drive is stopped in step S710, and in step S711. An ultrasonic stop process is executed. Thereafter, in step S709, it is determined whether or not the sheet conveyance is finished. If it is not the end of sheet conveyance, the process returns to step S704 again to determine the free space in the image memory.

  For example, the state where there is no free space in the image memory includes a case where it takes time to perform image processing on a read image, or a case where the sheet conveyance capability exceeds the image processing capability of the scanner.

  For example, the state where data cannot be transferred to the PC means that it takes a long time for image processing or image storage on the PC, the data transfer speed to the PC is slow, or the PC shifts to a standby state or hibernation state. If you do.

  If it is determined in step S709 that the sheet conveyance is completed, a scan end process is executed in step S712, and the process ends in step S713.

(Example 2)
FIG. 5 is a diagram illustrating a double feed detection device 501 that is a modification of the double feed detection device 101 for detecting overlap of sheets using ultrasonic waves.

  The double feed detection device 501 in FIG. 5 has basically the same configuration as that of the document reading device 100 described above. The same components are denoted by the same reference numerals and redundant description is omitted, and different configurations are described below. The element will be described.

  In FIG. 5, the double feed detection device 501 includes an audible sound receiving circuit 102H as a circuit for receiving a signal output from the sound wave receiving unit 4b in addition to the above-described ultrasonic wave receiving circuit 102E.

  Assuming that the frequency of the ultrasonic wave to be used is 300 kHz, the signal amplification circuit 110 in the ultrasonic wave reception circuit 102E has a function of selectively amplifying a frequency in the vicinity of 300 kHz. If an operational amplifier is used, it is possible to amplify a signal aiming at a specific frequency. Alternatively, a filter circuit that passes a specific frequency band may be used.

  The signal amplification circuit 112 in the audible sound receiving circuit 102H has a function of selectively amplifying a frequency of 20 Hz to 20 kHz. If an operational amplifier is used, it is possible to amplify a signal aiming at a specific frequency. Alternatively, a filter circuit that passes a specific frequency band may be used.

  The CPU 102A monitors the sheet conveyance sound in the audible range, and controls to transmit an ultrasonic wave from the sound wave transmission unit 4a when the sheet is conveyed. FIG. 5 introduces a configuration in which the CPU 102A directly controls the transport drive circuit 102G. However, the present invention is not limited to this, and a configuration having another CPU for transport control is also conceivable. In the case where there are a plurality of control CPUs as described above, the function that allows the CPU 102A to independently monitor the conveyance sound of the sheet and control the transmission and stop of the ultrasonic wave as in this embodiment works effectively.

  Also, from the output of the audible sound receiving circuit 102H, not only the presence / absence of the conveyance of the sheet is detected by the presence / absence of the conveyance sound, but also a function of detecting the presence / absence of a paper jam such as a jam and the presence / absence of the motor step-out is provided. May be allowed.

  Further, not only the presence / absence of the conveyance of the sheet is detected from the output of the audible sound receiving circuit 102H, but also a function of identifying a command based on the sound produced by the apparatus operator may be provided.

  FIG. 6 is a flowchart showing ultrasonic control of a modification of the document reading apparatus according to the embodiment of the present invention.

  The flow of ultrasonic control starting from step S601 of ultrasonic transmission control will be described with reference to FIG.

  When sheet conveyance start step S602 is executed by the apparatus operator, the CPU as the control unit of the apparatus receives an audible sound in step S603, and determines whether or not the sheet is being conveyed from the audible sound in step S604. .

  If it is determined in step S604 that the sheet is being conveyed, an ultrasonic transmission process is executed in step S605, an ultrasonic reception process is executed in step S606, and an ultrasonic reception signal is also received in step S607. In addition, the double feed of the sheet is detected. Thereafter, in step S608, it is determined whether or not the sheet conveyance is finished. If it is not the end of sheet conveyance, the process returns to the reception of the audible sound in step S603 again.

  If it is determined in step S604 that the sheet is not being conveyed, an ultrasonic stop process is executed in step S609, and it is determined in step S608 whether or not the sheet conveyance is completed. If it is not the end of sheet conveyance, the process returns to the reception of the audible sound in step S603 again.

  If it is determined in step S608 that the sheet conveyance is completed, an ultrasonic stop process is executed in step S610, and the process ends in step S611.

  Another object of the present invention is to supply a storage medium storing software program codes for realizing the functions of the above-described embodiments to a system or apparatus, and the computer of the system or apparatus (or CPU, MPU, or the like). Is also achieved by reading and executing the program code stored in the storage medium.

  In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments, and the program code and the storage medium storing the program code constitute the present invention. .

  Examples of the storage medium for supplying the program code include a floppy (registered trademark) disk, a hard disk, a magneto-optical disk, a CD-ROM, a CD-R, a CD-RW, a DVD-ROM, a DVD-RAM, and a DVD. An optical disc such as RW or DVD + RW, a magnetic tape, a nonvolatile memory card, a ROM, or the like can be used. Alternatively, the program code may be downloaded via a network.

  Further, by executing the program code read by the computer, not only the functions of the above-described embodiments are realized, but also an OS (Operating System) running on the computer based on the instruction of the program code Includes a case where the functions of the above-described embodiments are realized by performing part or all of the actual processing.

  Furthermore, after the program code read from the storage medium is written to a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer, the expanded function is based on the instruction of the program code. This includes a case where a CPU or the like provided on the expansion board or the expansion unit performs part or all of the actual processing and the functions of the above-described embodiments are realized by the processing.

DESCRIPTION OF SYMBOLS 100 Document reading apparatus 1 Document base F Document 2 Pickup roller 3 Retard roller 4a Sound wave transmission part 4b Sound wave receiving part 5a, 5b Conveying roller pair 7a, 7b Conveying roller pair 6a Image reading sensor 6b on the front side Image reading sensor 8 on the back side Discharge stacking unit 101 Double feed detection device 102 Control unit 102A CPU
102B ROM
102C RAM
102D ultrasonic transmission circuit 102E ultrasonic reception circuit 110 signal amplification circuit 111 AD converter 102F arithmetic unit 102G conveyance drive circuit 105 conveyance unit 201 document 202 conveyance path 501 double feed detection device 102H audible sound reception circuit 112 signal amplification circuit 113 A-D converter

Claims (8)

A transport unit that transports the sheet along the transport path;
A conveyance control unit for controlling start and stop of sheet conveyance by the conveyance unit;
A double feed detector for detecting double feed of sheets by an ultrasonic method in the transport path;
A double feed detection control unit for controlling ultrasonic transmission in the double feed detection unit,
The multi-feed detection control unit controls the ultrasonic transmission in the multi-feed detection unit to be stopped based on stop control of sheet conveyance by the conveyance control unit.   The multi-feed detection unit resumes ultrasonic transmission at the multi-feed detection unit from a state where ultrasonic transmission at the multi-feed detection unit is stopped based on sheet conveyance start control by the conveyance control unit. The sheet conveying apparatus according to claim 1, wherein the sheet conveying device is controlled as follows. A sound wave transmitting unit that is provided in the sheet conveyance path and transmits ultrasonic waves;
A sound wave receiving unit provided opposite to the sound wave transmitting unit across the transport path, and outputting a signal corresponding to the received sound wave;
An ultrasonic reception signal generation unit that generates an ultrasonic reception signal by amplifying a signal having a frequency in an ultrasonic band from the signal output from the acoustic wave reception unit;
A multi-feed determination unit that determines whether a plurality of sheets are overlapped and conveyed in the conveyance path based on the ultrasonic reception signal;
A conveyance control unit for controlling conveyance and stopping of the sheet;
In a state where the sheet passes between the sound wave transmitting unit and the sound wave receiving unit, a sound wave transmission control unit that controls the sound wave transmitting unit according to the stop of the conveyance of the sheet and stops the transmission of the ultrasonic wave,
A sheet conveying apparatus comprising:   The sheet conveyance device according to claim 3, wherein the sound wave transmission control unit stops the transmission of the ultrasonic wave based on the information that the conveyance from the conveyance control unit is stopped. An audible sound reception signal generating unit for amplifying an audible frequency signal from the signal output from the sound wave receiving unit to generate an audible sound reception signal;
A conveyance stop determination unit that determines whether the sheet is being conveyed or stopped from the audible sound reception signal,
The sheet conveyance device according to claim 3, wherein the sound wave transmission control unit stops transmission of ultrasonic waves based on the determination of the conveyance stop determination unit.   The sheet conveyance apparatus according to claim 5, further comprising a conveyance abnormality determination unit that determines conveyance abnormality from a sheet conveyance sound based on the audible range reception signal.   The sheet conveying apparatus according to claim 5, further comprising: a voice determination unit that determines a control command based on a voice of the apparatus operator based on the audible range reception signal.   An image reading apparatus comprising the sheet conveying apparatus according to claim 1.

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