JP2019123604A - Double feed detection device, double feed detection method and control program - Google Patents

Abstract

To provide a double feed detection device which can detect double feed with a better accuracy, a double feed detection method and a control program.SOLUTION: A double feed detection device 100 has: a sound wave oscillator 115a which can output audible sound and ultrasonic wave; an ultrasonic receiver 115b which is so located as to face the sound wave oscillator, and outputs an ultrasonic signal according to received ultrasonic wave; an audible sound receiver 113 which outputs an audible sound signal according to a received audible sound; a control part 161 which causes the sound wave oscillator to output audible sound or ultrasonic wave; a setting part 162 which sets a double feed determination threshold based on the audible sound signal; and a detection part 165 which detects that sheet double feed occurs based on a signal value of the ultrasonic signal and the double feed determination threshold.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a double feed detection device, a double feed detection method, and a control program, and more particularly to a double feed detection device that detects double feed using ultrasonic waves, a double feed detection method, and a control program.

  An apparatus such as a scanner which conveys an original and reads an image of the conveyed original has a function of detecting whether or not double feeding has occurred in which a plurality of originals are overlapped and conveyed. In general, a double feed detection apparatus such as a scanner includes an acoustic wave oscillator for outputting ultrasonic waves and an ultrasonic wave receiver for outputting a signal according to the received ultrasonic waves, and the ultrasonic wave receiver is used when a document is conveyed. Double feed is detected based on the output signal.

  There is disclosed an image reading apparatus which transmits ultrasonic waves toward a document sheet being conveyed, and determines that double feeding is performed when the reception level of the ultrasonic waves passing through the document sheet is equal to or less than a predetermined threshold ( See Patent Document 1).

JP, 2009-161291, A

  In the double feed detection device, it is desirable to detect double feed with higher accuracy.

  An object of the present invention is to provide a double feed detection device, a double feed detection method, and a control program capable of detecting double feed more accurately.

  A double feed detection device according to one aspect of the present invention includes an acoustic wave oscillator capable of outputting an audible sound and an ultrasonic wave, and an ultrasonic wave disposed opposite to the acoustic wave oscillator and outputting an ultrasonic signal according to the received ultrasonic wave. Based on the receiver, an audible sound receiver that outputs an audible sound signal according to the received audible sound, a control unit that causes the acoustic wave generator to output an audible sound or an ultrasonic wave, and the double feed determination threshold based on the audible sound signal. It has a setting unit to be set, and a detection unit to detect that double feeding of sheets has occurred based on the signal value of the ultrasonic signal and the double feeding determination threshold.

  A double feed detection method according to one aspect of the present invention includes an acoustic wave oscillator capable of outputting an audible sound and an ultrasonic wave, and an ultrasonic wave disposed opposite to the acoustic wave oscillator and outputting an ultrasonic signal according to the received ultrasonic wave. A double feed detection method in a double feed detection device comprising a receiver and an audible sound receiver for outputting an audible sound signal according to a received audible sound, wherein a sound sound generator outputs an audible sound or an ultrasonic wave. The method further includes setting a double feed determination threshold based on the audible sound signal and detecting occurrence of double feed of sheets based on the signal value of the ultrasonic signal and the double feed determination threshold.

  A control program according to one aspect of the present invention includes an acoustic wave oscillator capable of outputting audible sound and ultrasonic waves, and an ultrasonic wave receiver disposed opposite to the acoustic wave oscillator and outputting an ultrasonic wave signal according to the received ultrasonic wave. And an audible sound receiver for outputting an audible sound signal according to the received audible sound, the control program being executed by the double feed detection device, the audible sound or the ultrasonic wave being output from the sound wave oscillator, the audible sound The double feed determination threshold is set based on the signal, and the double feed detection device is made to detect that double feeding of sheets has occurred based on the signal value of the ultrasonic signal and the double feed determination threshold.

  According to the present invention, the double feed detection device can detect double feed more accurately.

It is a perspective view showing a double feed detection device 100 concerning an embodiment. It is a figure for demonstrating the conveyance path | route inside double feed detection apparatus 100. FIG. FIG. 2 is a block diagram showing a schematic configuration of a double feed detection device 100. An example of the data structure of an altitude table is shown. An example of a data structure of a threshold value table is shown. An example of a data structure of a temperature correction table is shown. An example of a data structure of a humidity correction table is shown. It is a figure which shows schematic structure of the memory | storage device 150 and CPU160. It is a flowchart which shows the example of operation | movement of a threshold value setting process. 6 is a flowchart illustrating an example of an operation of document reading processing. It is a flowchart which shows the example of operation | movement of abnormality determination processing. It is a flow chart which shows an example of operation of double feed judging processing. It is a figure for demonstrating the characteristic of an ultrasonic wave signal. 7 is a flowchart illustrating an example of the operation of the jam determination processing. 5 is a graph illustrating an example of a digital audible sound signal. It is a graph which shows the example of the signal which took the absolute value of the audible sound signal. It is a graph which shows the example of a contour signal. It is a graph which shows the example of the counter value calculated about the external shape signal. It is a graph which shows the relationship between an altitude and the signal value of an ultrasonic signal. It is a graph which shows the relationship between altitude and the sound pressure value of an audible sound. It is a graph which shows the relationship between temperature and height, and the signal value of an ultrasonic signal. It is a graph which shows the relationship between humidity and height, and the signal value of an ultrasonic signal. FIG. 16 is a diagram showing a schematic configuration of another processing circuit 270.

  Hereinafter, a double feed detection device according to one aspect of the present invention will be described with reference to the drawings. However, it should be noted that the technical scope of the present invention is not limited to those embodiments, but extends to the invention described in the claims and the equivalents thereof.

  FIG. 1 is a perspective view showing a double feed detection apparatus 100 configured as an image scanner. In the following, although the case where the double feed detection apparatus 100 is a document conveyance apparatus for feeding a document such as a sheet or a plastic card is described as an example, the double feed detection apparatus 100 is a medium such as a sheet or a plastic card As long as it is an apparatus which conveys, it may be any apparatus. For example, the double feed detection apparatus 100 may be a facsimile, an inkjet printer, a laser printer, a printer multifunction peripheral (MFP) or the like.

  The double feed detection apparatus 100 includes a lower housing 101, an upper housing 102, a document table 103, a discharge table 105, operation buttons 106, and the like.

  The upper housing 102 is disposed at a position covering the upper surface of the double feed detection apparatus 100, and is engaged with the lower housing 101 by a hinge so as to be openable and closable at the time of original cleaning, the inside of the double feed detection apparatus 100, etc. doing.

  The document table 103 is engaged with the lower housing 101 so as to place a document. The document table 103 is provided with side guides 104 a and 104 b movable in the direction orthogonal to the document conveyance direction. Hereinafter, the side guides 104 a and 104 b may be collectively referred to as a side guide 104.

  The discharge tray 105 is engaged with the lower housing 101 by a hinge so as to be rotatable in the direction indicated by the arrow A1, and holds the discharged document in the open state as shown in FIG. Is possible.

  The operation button 106 is disposed on the surface of the upper housing 102, and when pressed, generates and outputs an operation detection signal.

  FIG. 2 is a diagram for explaining the transport path inside the double feed detection apparatus 100. As shown in FIG.

  The conveyance path inside the double feed detection apparatus 100 includes an original detection sensor 110, a feed roller 111, a retard roller 112, a microphone 113, a sound wave oscillator 115a, an ultrasonic wave receiver 115b, a first conveyance roller 116, and a first driven roller 117. A first imaging device 119a, a second imaging device 119b, a second conveyance roller 120, a second driven roller 121, and the like are included. The number of each roller is not limited to one, and the number of each roller may be plural.

  The upper surface of the lower housing 101 forms a lower guide 107a of the document conveyance path, and the lower surface of the upper housing 102 forms an upper guide 107b of the document conveyance path. In FIG. 2, an arrow A2 indicates the transport direction of the document. Hereinafter, the upstream refers to the upstream of the document transport direction A2, and the downstream refers to the downstream of the document transport direction A2.

  The document detection sensor 110 has a contact detection sensor disposed on the upstream side of the feeding roller 111 and the retard roller 112, and detects whether a document is placed on the document table 103. The document detection sensor 110 generates and outputs a document detection signal in which the signal value changes depending on whether the document is placed on the document table 103 or not.

  The microphone 113 is an example of an audible sound receiver and is provided in the vicinity of the document conveyance path, and receives (collects) an audible sound generated while the document is being conveyed, or an audible sound output by the sound wave oscillator 115a. , Output an analog audible sound signal according to the received audible sound. The microphone 113 is disposed on the downstream side of the feed roller 111 and the retard roller 112, being fixed to the frame 108 inside the upper housing 102. A hole 109 is provided at a position facing the microphone 113 of the upper guide 107b so that the microphone 113 can more accurately collect the sound generated while the document is being conveyed.

  The sound wave oscillator 115a and the ultrasonic wave receiver 115b are disposed in the vicinity of the document conveyance path so as to face each other across the conveyance path. The frequency of the sound wave to be output can be set to the sound wave oscillator 115a, and the sound wave oscillator 115a can output an audible sound and an ultrasonic wave according to the set frequency. The frequency of the audible sound is 20 Hz or more and 20 kHz or less, and the frequency of the ultrasonic wave is more than 20 kHz and 300 MHz or less. On the other hand, the ultrasonic wave receiver 115b receives an ultrasonic wave oscillated by the sound wave oscillator 115a and having passed through the document, and generates and outputs an ultrasonic wave signal which is an electrical signal corresponding to the received ultrasonic wave. The sound wave generator 115 a and the ultrasonic wave receiver 115 b may be collectively referred to as an ultrasonic wave sensor 115 below.

  The first imaging device 119 a includes an imaging sensor of a reduction optical system type including an imaging element by a CCD (Charge Coupled Device) linearly arranged in the main scanning direction. The image sensor reads the back side of the document to generate and output an analog image signal. Similarly, the second imaging device 119 b includes an imaging sensor of a reduction optical system type provided with an imaging element by a CCD linearly arranged in the main scanning direction. The image sensor reads the surface of the document to generate and output an analog image signal. Alternatively, only one of the first imaging device 119a and the second imaging device 119b may be disposed, and only one side of the document may be read. Also, instead of the CCD, a CIS (Contact Image Sensor) of an equal magnification optical system type provided with an imaging device by a Complementary Metal Oxide Semiconductor (CMOS) can be used. Hereinafter, the first imaging device 119a and the second imaging device 119b may be collectively referred to as an imaging device 119.

  The document placed on the document table 103 is conveyed between the lower guide 107a and the upper guide 107b in the document conveyance direction A2 by the feed roller 111 rotating in the direction of the arrow A3 in FIG. . The retard roller 112 rotates in the direction of arrow A4 in FIG. When a plurality of documents are placed on the document table 103 by the functions of the feeding roller 111 and the retard roller 112, among the documents placed on the document table 103, only the documents in contact with the feeding roller 111 Are separated. As a result, the transport of the originals other than the separated originals is restricted (preventing double feed). The feed roller 111 and the retard roller 112 function as a document separation unit.

  The document is fed between the first conveying roller 116 and the first driven roller 117 while being guided by the lower guide 107 a and the upper guide 107 b. The document is sent between the first imaging device 119a and the second imaging device 119b by the rotation of the first conveyance roller 116 in the direction of the arrow A5 in FIG. The document read by the imaging device 119 is discharged onto the discharge table 105 by the second conveyance roller 120 rotating in the direction of arrow A6 in FIG.

  FIG. 3 is a block diagram showing a schematic configuration of the double feed detection apparatus 100. As shown in FIG.

  The double feed detection apparatus 100 has a first image A / D converter 130a, a second image A / D converter 130b, an absolute value signal generation circuit 131, an ultrasonic A / D converter 132, in addition to the above-described configuration. It further includes an audible sound signal generation unit 133, a drive device 137, an interface device 138, a temperature sensor 139, a humidity sensor 140, a storage device 150, a central processing unit (CPU) 160, a processing circuit 170, and the like.

  The first image A / D converter 130 a analog-digital converts the analog image signal output from the first imaging device 119 a to generate digital image data, and outputs the digital image data to the CPU 160 and the processing circuit 170. Similarly, the second image A / D converter 130 b analog-digital converts the analog image signal output from the second imaging device 119 b to generate digital image data, and outputs the digital image data to the CPU 160 and the processing circuit 170. Hereinafter, these digital image data are referred to as a read image. In the following, the first image A / D converter 130a and the second image A / D converter 130b may be collectively referred to as an image A / D converter 130.

  The absolute value signal generation circuit 131 generates an absolute value signal obtained by taking the absolute value of the analog ultrasonic signal output from the ultrasonic sensor 115, and outputs the generated absolute value signal to the ultrasonic A / D converter 132.

  The ultrasonic A / D converter 132 converts the absolute value signal output from the absolute value signal generation circuit 131 from analog to digital to generate a digital ultrasonic signal, and outputs the digital ultrasonic signal to the CPU 160.

  The audible sound signal generation unit 133 includes a microphone 113, a filter 134, an amplifier 135, a sound A / D converter 136, and the like. The filter 134 applies a band pass filter that passes a signal of a predetermined frequency band to the analog audio sound signal output from the microphone 113, and outputs the band pass filter to the amplifier 135. The amplifier 135 amplifies the signal output from the filter 134 and outputs the amplified signal to the sound A / D converter 136. The sound A / D converter 136 samples the signal output from the amplifier 135 at predetermined intervals, generates a digital audible sound signal obtained by digital conversion, and outputs the signal to the CPU 160.

  The driving device 137 includes one or more motors, and rotates the feeding roller 111, the retard roller 112, the first conveying roller 116, and the second conveying roller 120 according to a control signal from the CPU 160 to convey the document. Do.

  The interface device 138 has an interface circuit conforming to a serial bus such as USB, for example, and is electrically connected to an information processing device (for example, a personal computer, a portable information terminal, etc.) (not shown) to read a read image and various information. Send and receive. Also, instead of the interface device 138, a communication unit having an antenna for transmitting and receiving a wireless signal and a wireless communication interface device for transmitting and receiving a signal through a wireless communication channel in accordance with a predetermined communication protocol may be used. The predetermined communication protocol is, for example, a wireless LAN (Local Area Network).

  The temperature sensor 139 detects the temperature (air temperature) in the double feed detection device 100, and outputs temperature information indicating the detected temperature to the CPU 160.

  The humidity sensor 140 detects the humidity in the double feed detection apparatus 100, and outputs humidity information indicating the detected humidity to the CPU 160.

  The storage device 150 includes a memory device such as a random access memory (RAM) or a read only memory (ROM), a fixed disk device such as a hard disk, or a portable storage device such as a flexible disk or an optical disk. Further, the storage device 150 stores a computer program, a database, a table, and the like used for various processes of the double feed detection apparatus 100. The computer program may be installed in the storage device 150 from a computer readable portable recording medium using a known setup program or the like. The portable recording medium is, for example, a CD-ROM (compact disk read only memory), a DVD-ROM (digital versatile disk read only memory) or the like.

  The storage device 150 also stores a read image, a double feed determination threshold value, an altitude table, a threshold value table, a temperature correction table, a humidity correction table, and the like. The double feed determination threshold is a threshold used in the double feed determination process that determines whether double feed of sheets has occurred. Details of the altitude table, the threshold table, the temperature correction table, and the humidity correction table will be described later.

  The CPU 160 operates based on a program stored in advance in the storage device 150. Note that, in place of the CPU 160, a digital signal processor (DSP), a large scale integration (LSI), or the like may be used. Further, instead of the CPU 160, an application specific integrated circuit (ASIC), a field-programming gate array (FPGA), or the like may be used.

  The CPU 160 includes an operation button 106, an original detection sensor 110, an ultrasonic sensor 115, a first imaging device 119a, a second imaging device 119b, a first image A / D converter 130a, a second image A / D converter 130b, The sound wave A / D converter 132, the audible sound signal generation unit 133, the drive device 137, the interface device 138, the temperature sensor 139, the humidity sensor 140, the storage device 150, the processing circuit 170 and the like are connected to control these units. The CPU 160 performs drive control of the drive device 137, document reading control of the imaging device 119, and the like, and acquires a read image. The CPU 160 also sets a double feed determination threshold, and performs double feed detection processing and the like based on the set double feed determination threshold.

  The processing circuit 170 executes predetermined image processing on the read image output from the read image, and stores the read image subjected to the image processing in the storage device 150. Note that, instead of the processing circuit 170, a DSP, an LSI, an ASIC, an FPGA, or the like may be used.

  FIG. 4A shows an example of the data structure of the height table.

  As shown in FIG. 4A, in the height table, a range of signal values of the digital audible sound signal output from the sound A / D converter 136 when the sound wave oscillator 115a outputs a predetermined audible sound, and double feed detection The altitude range of the installation site of the apparatus 100 is associated and stored. The altitude table is a digital audio output from the sound A / D converter 136 when the sound wave oscillator 115a outputs a predetermined audible sound with the double feed detection device 100 placed at various altitudes (a barometric pressure environment). It sets up based on the experimental result which measured the signal value of the hearing aid signal.

  FIG. 4B shows an example of the data structure of the threshold value table.

  As shown in FIG. 4B, in the threshold table, the range of the height of the installation place of the double feed detection apparatus 100 and the double feed determination threshold are stored in association with each other. Each double feed determination threshold is output by the ultrasonic A / D converter 132 when the ultrasonic wave generator 115a outputs a predetermined ultrasonic wave in a state where the double feed detection device 100 is placed at various altitudes (pressure environment). It sets based on the experimental result which measured the signal value of the digital ultrasonic signal to be. Each double-feed judgment threshold value is set to a value between the signal value of the ultrasonic signal of the ultrasonic wave which has passed one sheet of paper and the signal value of the ultrasonic signal of the ultrasonic wave which has passed two sheets of paper Be done.

  FIG. 4C shows an example of the data structure of the temperature correction table.

  As shown in FIG. 4C, the temperature correction table stores the temperature range of the double feed detection device 100 in association with the temperature correction coefficient. The temperature correction coefficient is a coefficient for correcting the double feed determination threshold by multiplying the double feed determination threshold. A coefficient for adding, subtracting, or dividing the double feed determination threshold may be set as the temperature correction coefficient. Each temperature correction coefficient is a digital signal output from the ultrasonic A / D converter 132 when the ultrasonic wave generator 115a outputs a predetermined ultrasonic wave in a state where the double feed detection device 100 is placed in various temperature environments. It sets up based on the experimental result which measured the signal value of the sound wave signal. For example, 1 is set as the temperature correction coefficient at normal temperature, and the ratio of the signal value of the ultrasonic signal at each temperature to the signal value of the ultrasonic signal at normal temperature is set as the temperature correction coefficient at other temperatures. Each temperature correction coefficient is set to be lower as the temperature is lower.

  FIG. 4D shows an example of the data structure of the humidity correction table.

  As shown in FIG. 4D, the humidity correction table stores the humidity range of the double feed detection device 100 in association with the humidity correction coefficient. The humidity correction coefficient is a coefficient for correcting the double feed determination threshold by multiplying the double feed determination threshold. Note that, as the humidity correction coefficient, a coefficient to be added to, subtracted from or divided from the double feed determination threshold may be set. The respective humidity correction coefficients are digital super signals output from the ultrasonic A / D converter 132 when the ultrasonic wave generator 115 a outputs a predetermined ultrasonic wave in a state where the double feed detection device 100 is placed in various humidity environments. It sets up based on the experimental result which measured the signal value of the sound wave signal. For example, 1 is set as the correction coefficient at the time of normal humidity, and the ratio of the signal value of the ultrasonic signal at each humidity to the signal value of the ultrasonic signal at the time of normal humidity is set as another correction coefficient of humidity.

  FIG. 5 is a diagram showing a schematic configuration of the storage device 150 and the CPU 160. As shown in FIG.

  As shown in FIG. 5, the storage device 150 stores programs such as a control program 151, a setting program 152, a correction program 153, an image generation program 154, a detection program 155, and a jam determination program 156. Each of these programs is a functional module implemented by software operating on the processor. The CPU 160 reads each program stored in the storage device 150 and operates in accordance with each read program, whereby the control unit 161, the setting unit 162, the correction unit 163, the image generation unit 164, the detection unit 165, and the jam determination unit 166. Act as.

  FIG. 6 is a flowchart showing an example of the operation of the threshold setting process of the double feed detection apparatus 100.

  Hereinafter, an example of the operation of the threshold setting process of the double feed detection device 100 will be described with reference to the flowchart shown in FIG. The flow of the operation described below is executed mainly by the CPU 160 in cooperation with each element of the double feed detection apparatus 100 based on a program stored in advance in the storage device 150. The flow of the operation shown in FIG. 5 is executed, for example, at the time of initialization (powering up of the apparatus) after the power-on of the double feed detection apparatus 100.

  First, the control unit 161 sets the frequency of the sound wave output from the sound wave oscillator 115a in the frequency band of the audible sound, and causes the sound wave oscillator 115a to output a predetermined audible sound (step S101).

  Next, the setting unit 162 acquires a digital audible sound signal from the microphone 113 via the sound A / D converter 136 (step S102).

  Next, the setting unit 162 estimates the height of the installation place of the double feed detection device 100 based on the acquired audible sound signal (step S103). The setting unit 162 identifies the altitude corresponding to the signal value of the acquired audible sound signal from the altitude table, and estimates the identified altitude as the altitude of the installation location of the double feed detection apparatus 100.

  Next, the setting unit 162 sets the double feed determination threshold based on the estimated height (step S104). The setting unit 162 specifies the double feed determination threshold value corresponding to the estimated height from the threshold value table, and sets the specified double feed determination threshold value in the storage device 150 as the double feed determination threshold value used in the double feed determination process.

  Next, the correction unit 163 acquires temperature information from the temperature sensor 139 (step S105).

  Next, the correction unit 163 corrects the double feed determination threshold based on the temperature indicated by the acquired temperature information (step S106). The correction unit 163 specifies the temperature correction coefficient corresponding to the temperature indicated in the temperature information from the temperature correction table, corrects the double feed determination threshold by multiplying the double feed determination threshold by the specified temperature correction coefficient, and stores The information is stored in the device 150.

  Next, the correction unit 163 acquires humidity information from the humidity sensor 140 (step S107).

  Next, the correction unit 163 corrects the double feed determination threshold based on the humidity indicated by the acquired humidity information (step S108), and ends the series of steps. The correction unit 163 specifies the humidity correction coefficient corresponding to the humidity indicated in the humidity information from the humidity correction table, corrects the double feed determination threshold by multiplying the double feed determination threshold by the specified humidity correction coefficient, and stores The information is stored in the device 150.

  Note that the correction unit 163 may omit the process of steps S105 and S106 or the process of steps S107 and S108.

  FIG. 7 is a flowchart showing an example of the document reading process of the double feed detection apparatus 100.

  Hereinafter, an example of the document reading process of the double feed detection apparatus 100 will be described with reference to the flowchart shown in FIG. The flow of the operation described below is executed mainly by the CPU 160 in cooperation with each element of the double feed detection apparatus 100 based on a program stored in advance in the storage device 150. The flow of operation shown in FIG. 7 is periodically performed.

  First, the control unit 161 waits until the user presses the operation button 106 for instructing reading of a document and receives an operation detection signal for instructing reading of the document from the operation button 106 (step S201). ).

  Next, the control unit 161 determines whether a document is placed on the document table 103 based on the document detection signal received from the document detection sensor 110 (step S202).

  If a document is not placed on the document table 103, the control unit 161 returns the process to step S201 and stands by until a new operation detection signal is received from the operation button 106.

  On the other hand, when a document is placed on the document table 103, the control unit 161 drives the drive device 137 to rotate the feed roller 111, the retard roller 112, the first conveyance roller 116, and the second conveyance roller 120. And transport the original (step S203).

  Next, the control unit 161 determines whether the abnormality occurrence flag is ON (step S204). The abnormality occurrence flag is set to OFF when the double feed detection device 100 is activated, and is set to ON when it is determined that an abnormality has occurred in abnormality determination processing described later.

  When the abnormality occurrence flag is ON, the control unit 161 stops the driving device 137 to stop the conveyance of the document as the abnormality processing. In addition, the control unit 161 notifies the user that an abnormality has occurred using a speaker (not shown), an LED (Light Emitting Diode), etc., sets the abnormality occurrence flag to OFF (step S205), and executes a series of steps. finish.

  On the other hand, when the abnormality occurrence flag is not ON, the image generation unit 164 causes the imaging device 119 to read the conveyed document, and acquires a read image via the image A / D converter 130 (step S206).

  Next, the image generation unit 164 transmits the read image to an information processing apparatus (not shown) via the interface apparatus 138 (step S207). When the image generation unit 164 is not connected to the information processing apparatus, the read image is stored in the storage device 150.

  Next, the control unit 161 determines whether a document remains on the document table 103 based on the document detection signal received from the document detection sensor 110 (step S208).

  If a document remains on the document table 103, the control unit 161 returns the process to step S203 and repeats the process of steps S203 to S208. On the other hand, when no document remains on the document table 103, the control unit 161 ends the series of steps.

  FIG. 8 is a flowchart illustrating an example of the operation of the abnormality determination process.

  The flow of the operation described below is mainly executed by the CPU 160 in cooperation with each element of the double feed detection apparatus 100 based on a program stored in advance in the storage device 150. The flowchart shown in FIG. 8 is executed at predetermined time intervals while the document is being conveyed. Before the abnormality determination process is performed, the control unit 161 sets the frequency of the sound wave output from the sound wave oscillator 115a in the frequency band of the ultrasonic wave, and causes the sound wave oscillator 115a to output a predetermined ultrasonic wave.

  First, the detection unit 165 carries out a double feed determination process (step S301). The detection unit 165 determines that double feeding of sheets has occurred based on the signal value of the ultrasonic wave signal acquired from the ultrasonic sensor 115 and the double feeding determination threshold set in the storage device 150 in the double feeding determination process. To detect. The details of the double feed determination process will be described later.

  Next, the jam determination unit 166 carries out a jam determination process (step S302). In the jam determination processing, the jam determining unit 166 determines whether a sheet jam has occurred based on the digital audible sound signal acquired from the sound A / D converter 136. Details of the jam determination processing will be described later.

  Next, the control unit 161 determines whether or not an abnormality has occurred in the document conveyance process (step S303). The control unit 161 determines that an abnormality has occurred when at least one of double feeding of paper and jamming has occurred. That is, the control unit 161 determines that an abnormality does not occur only when neither double-feeding of paper nor jamming has occurred.

  When an abnormality occurs in the document conveyance process, the control unit 161 sets the abnormality occurrence flag to ON (step S304), and ends the series of steps. On the other hand, when an abnormality has not occurred in the document conveyance process, the control unit 161 does not particularly perform the process, and ends the series of steps.

  FIG. 9 is a flowchart showing an example of the operation of the double feed determination process.

  The flow of the operation shown in FIG. 9 is executed in step S301 of the flowchart shown in FIG.

  First, the detection unit 165 acquires a digital ultrasonic signal from the ultrasonic sensor 115 via the ultrasonic A / D converter 132 (step S401).

  Next, the detection unit 165 determines whether the signal value of the acquired ultrasound signal is less than the double-transmission determination threshold set in the storage device 150 (step S402).

  FIG. 10 is a diagram for explaining the characteristics of the ultrasonic signal.

  In the graph 1000 of FIG. 10, the solid line 1001 indicates the characteristic of the ultrasonic signal when one sheet of paper is being conveyed, and the dotted line 1002 indicates the characteristic of the ultrasonic signal when double feeding of the sheet is occurring. . The horizontal axis of the graph 1000 shows time, and the vertical axis shows the signal value of the ultrasonic signal. Due to the occurrence of double feeding, the signal value of the ultrasonic signal at the dotted line 1002 is lowered in the section 1003. Therefore, the detection unit 165 can determine whether or not double feeding of sheets has occurred based on whether or not the signal value of the ultrasonic signal is less than the double feeding determination threshold ThA.

  If the signal value of the ultrasonic signal is less than the double feed determination threshold, the detection unit 165 determines that double feed of sheets has occurred (step S403), and ends the series of steps. On the other hand, when the signal value of the ultrasonic signal is equal to or more than the double feed determination threshold value, the detection unit 165 determines that double feed of sheets has not occurred (step S404), and ends the series of steps. As described above, the detection unit 165 detects the occurrence of double feeding of sheets based on the signal value of the ultrasonic signal and the double feeding determination threshold.

  FIG. 11 is a flowchart illustrating an example of the operation of the jam determination processing.

  The flow of operation shown in FIG. 11 is executed in step S302 of the flowchart shown in FIG.

  First, the jam determination unit 166 obtains a digital audible sound signal from the sound A / D converter 136 (step S501).

  FIG. 12A is a graph showing an example of a digital audible sound signal. A graph 1200 shown in FIG. 12A represents the audible sound signal output from the sound A / D converter 136. The horizontal axis of the graph 1200 shows time, and the vertical axis shows signal values.

  Next, the jam determination unit 166 generates a signal obtained by taking an absolute value of the audible sound signal output from the sound A / D converter 136 (step S502).

  FIG. 12B is a graph showing an example of an absolute sound signal of an audible sound signal. A graph 1210 shown in FIG. 12B represents a signal obtained by taking the absolute value of the audible sound signal of the graph 1200. The horizontal axis of the graph 1210 indicates time, and the vertical axis indicates the absolute value of the signal value.

  Next, the jam determining unit 166 generates an outer shape signal from which the outer shape of the signal obtained by taking the absolute value of the audible sound signal is extracted (step S503). The jam determining unit 166 extracts an envelope as the outer shape signal.

  FIG. 12C is a graph showing an example of the outline signal. A graph 1220 shown in FIG. 12C represents an envelope 1221 of a signal obtained by taking the absolute value of the audible sound signal of the graph 1210. The horizontal axis of the graph 1220 shows time, and the vertical axis shows the absolute value of the signal value.

  Next, the jam determining unit 166 calculates a counter value to be increased when the outer shape signal is the first threshold Th1 or more and to be decreased when the outer shape signal is less than the first threshold Th1 (step S504). The jam determining unit 166 determines whether the value of the envelope 1221 is equal to or greater than the first threshold Th1 at predetermined time intervals (for example, sampling intervals of analog-to-digital conversion). The jam determining unit 166 increments the counter value when the value of the envelope 1221 is equal to or greater than the first threshold Th1, and decrements the counter value when the envelope 1221 is less than the first threshold Th1.

  FIG. 12D is a graph showing an example of counter values calculated for the outer shape signal. A graph 1230 shown in FIG. 12D represents the counter value calculated for the envelope 1221 of the graph 1220. The horizontal axis of the graph 1220 indicates time, and the vertical axis indicates the counter value.

  Next, the jam determining unit 166 determines whether the counter value is greater than or equal to the second threshold Th2 (step S505). The jam determining unit 166 determines that a jam has occurred if the counter value is equal to or greater than the second threshold Th2 (step S506), and determines that a jam has not occurred if the counter value is less than the second threshold Th2. (Step S507), and a series of steps are completed.

  In FIG. 12C, the envelope 1221 becomes equal to or greater than the first threshold Th1 at time T1, and thereafter does not become smaller than the first threshold Th1. Therefore, as shown in FIG. 12D, the counter value increases from time T1 and becomes greater than or equal to the second threshold Th2 at time T2, and the jam determining unit 166 determines that a jam has occurred.

  In step S503, the jam determination unit 166 may obtain a signal obtained by peak-holding a signal obtained by taking an absolute value of an audible sound signal at predetermined intervals, instead of obtaining an envelope as the outer shape signal. In addition, the jam determination unit 166 may obtain, as the outer shape signal, a signal obtained by applying a known smoothing filter, averaging filter, or low pass filter to a signal obtained by taking an absolute value of an audible sound signal.

  The technical significance of setting the double feed determination threshold based on the audible sound signal will be described below.

  FIG. 13A is a graph showing the relationship between the altitude at which the double feed detection apparatus 100 is installed and the signal value of the ultrasonic signal output when the double feed detection apparatus 100 is installed at each height.

  The horizontal axis of FIG. 13A indicates the altitude [km] at which the double feed detection device 100 is installed, and the vertical axis indicates the signal value of the ultrasonic signal. A graph 1301 shows signal values of ultrasonic signals when one PPC sheet is conveyed, and a graph 1302 shows signal values of ultrasonic signals when two PPC sheets are conveyed. As shown in FIG. 13A, the higher the altitude at which the double feed detection apparatus 100 is installed, that is, the lower the air pressure in the double feed detection apparatus 100, the more the ultrasonic wave is attenuated and the signal value of the ultrasonic signal is lower. .

  For example, when the double feed determination threshold is 15, the double feed detection apparatus 100 determines whether one PPC sheet is being transported or two PPC sheets are being transported in an environment where the altitude is less than 2.5 km. It can be determined correctly. However, in an environment where the altitude is 2.5 km or more, both the signal value when one PPC sheet is conveyed and the signal value when two PPC sheets are conveyed become less than the double feed determination threshold, The double feed detection device 100 can not distinguish between the two correctly. When the double feed determination threshold is 5, the double feed detection apparatus 100 correctly determines whether one PPC sheet is being transported or two PPC sheets are being transported in an environment where the altitude is 1 km or more. can do. However, in an environment where the altitude is less than 1 km, the signal value when one sheet of PPC sheet is conveyed and the signal value when two sheets of PPC sheet are conveyed become equal to or more than the double feed determination threshold. The detection device 100 can not distinguish between the two correctly.

  Therefore, the double feed detection apparatus 100 sets the double feed determination threshold to be lower as the height of the installation place is higher, thereby determining whether double feed of sheets has occurred regardless of the height of the installation place. It can be determined correctly. In particular, when the double feed detection apparatus 100 is installed at an altitude of 0 km to 5 km, it can correctly determine whether double feed of sheets has occurred.

  FIG. 13B shows the relationship between the altitude at which the double feed detection apparatus 100 is installed and the sound pressure value of the predetermined audible sound collected by the microphone 113 when the double feed detection apparatus 100 is installed at each height. FIG.

  The horizontal axis in FIG. 13B indicates the altitude [km] at which the double feed detection device 100 is installed, and the vertical axis indicates the sound pressure value [dB]. The graph 1311 shows a theoretical value, and the graph 1312 shows an experimentally measured value. As shown in FIG. 13B, the higher the altitude at which the double feed detection device 100 is installed, that is, the lower the barometric pressure in the double feed detection device 100, the more the audible sound is attenuated and the lower the sound pressure value.

  Therefore, the double feed detection device 100 can estimate the height of the installation location of the double feed detection device 100 from the signal value of the audible sound signal based on the predetermined audible sound.

  FIG. 14A shows the temperature and altitude (barometric pressure) of the environment in which the double feed detection apparatus 100 is installed, and the signal value of the ultrasonic signal output when the double feed detection apparatus 100 is installed in each environment. It is a graph which shows a relation.

  The horizontal axis of FIG. 14A indicates the altitude [km] at which the double feed detection device 100 is installed, and the vertical axis indicates the signal value of the ultrasonic signal. A graph 1401 indicates the signal value of the ultrasonic signal when one PPC sheet is transported while the temperature in the double feed detection apparatus 100 is 60 ° C. A graph 1402 indicates the signal value of the ultrasonic signal when one PPC sheet is transported in a state where the temperature in the double feed detection apparatus 100 is 25 ° C. A graph 1403 indicates the signal value of the ultrasonic signal when one PPC sheet is transported while the temperature in the double feed detection apparatus 100 is 0 ° C. The graph 1404 shows the signal values of the ultrasonic signals when the two PPC sheets are transported while the temperature in the double feed detection apparatus 100 is 60.degree. A graph 1405 shows the signal values of ultrasonic signals when two sheets of PPC paper are transported while the temperature in the double feed detection apparatus 100 is 25 ° C. A graph 1406 shows signal values of ultrasonic signals when two sheets of PPC paper are transported while the temperature in the double feed detection apparatus 100 is 0 ° C.

  As shown in FIG. 14A, as the temperature in the double feed detection device 100 is lower, the ultrasonic wave is attenuated and the signal value of the ultrasonic wave signal is lower. Therefore, the detection unit 165 corrects the double feed determination threshold so that the lower the temperature in the double feed detection device 100, the lower the temperature of the environment in which the double feed detection device 100 is installed. It can be determined with high accuracy whether double feed of paper has occurred.

  FIG. 14B shows the humidity and altitude (barometric pressure) of the environment where the double feed detection apparatus 100 is installed, and the signal value of the ultrasonic signal output when the double feed detection apparatus 100 is installed in each environment. It is a graph which shows a relation.

  The horizontal axis in FIG. 14B indicates the altitude [km] at which the double feed detection device 100 is installed, and the vertical axis indicates the signal value of the ultrasonic signal. A graph 1411 shows the signal value of the ultrasonic signal when one PPC sheet is transported in a state where the humidity in the double feed detection apparatus 100 is 80%. A graph 1412 shows signal values of ultrasonic signals when one sheet of PPC paper is transported in a state where the humidity in the double feed detection apparatus 100 is 50%. A graph 1413 shows signal values of ultrasonic signals when one sheet of PPC paper is transported in a state where the humidity in the double feed detection apparatus 100 is 30%. A graph 1414 shows signal values of ultrasonic signals when two sheets of PPC paper are transported in a state where the humidity in the double feed detection apparatus 100 is 80%. A graph 1415 shows the signal values of ultrasonic signals when two sheets of PPC paper are transported in a state where the humidity in the double feed detection apparatus 100 is 50%. A graph 1416 shows the signal values of ultrasonic signals when two sheets of PPC paper are transported in a state where the humidity in the double feed detection apparatus 100 is 30%.

  As shown in FIG. 14B, the signal value of the ultrasonic signal changes in accordance with the humidity in the double feed detection device 100. Therefore, the detection unit 165 corrects the double feed determination threshold based on the humidity in the double feed detection device 100 to cause double feeding of sheets regardless of the humidity of the environment in which the double feed detection device 100 is installed. It can be determined with high accuracy whether or not it has.

  As described above in detail, the double feed detection device 100 causes the sound wave oscillator 115a to output an audible sound by operating according to the flowcharts shown in FIGS. 6 to 9, and the double feed is performed based on the audible sound received by the microphone 113. Set the judgment threshold. Then, the double feed detection device 100 determines whether double feed has occurred based on the set double feed determination threshold. As a result, the double feed detection device 100 can detect double feed more accurately.

  The double feed detection apparatus 100 estimates the height at which the double feed detection apparatus 100 is installed, using the microphone 113 used to determine whether or not a jam has occurred. Since the double feed detection device 100 does not need to provide a special sensor for detecting the height at which the double feed detection device 100 is installed, an appropriate weight can be obtained while suppressing an increase in device size and an increase in device cost. It has become possible to set the sending judgment threshold. Also, the user does not need to disable the double feed detection function in order to prevent false detection of double feed when the double feed detection apparatus 100 is used in a specific advanced environment, It has become possible to improve the convenience of users. Further, since the double feed detection device 100 causes the sound wave oscillator 115a to output a predetermined audible sound only at the time of initialization after the power on of the double feed detection device 100 (when the device is started), the audible sound is the user's It can be suppressed to be offensive.

  FIG. 15 is a diagram showing a schematic configuration of the processing circuit 270 in the double feed detection device according to another embodiment. The processing circuit 270 includes a control circuit 271, a setting circuit 272, a correction circuit 273, an image generation circuit 274, a detection circuit 275, a jam determination circuit 276, and the like. Note that each of these units may be configured by an integrated circuit, a microprocessor, firmware or the like that is independent of each other.

  The control circuit 271 is an example of a control unit. The control circuit 271 transmits an acoustic wave control signal to the acoustic wave oscillator 115a to cause the acoustic wave oscillator 115a to output an audible sound or an ultrasonic wave. Further, the control circuit 271 transmits a drive control signal to the drive device 137 to drive the drive device 137 and transport the document.

  The setting circuit 272 is an example of a setting unit. The setting circuit 272 receives a digital audible sound signal from the sound A / D converter 136, and sets the double feed determination threshold in the storage device 150 based on the received audible sound signal.

  The correction circuit 273 is an example of a correction unit. The correction circuit 273 receives temperature information from the temperature sensor 139, and corrects the double feed determination threshold based on the received temperature information. Further, the correction circuit 273 receives the humidity information from the humidity sensor 140, and corrects the double feed determination threshold based on the received humidity information.

  The image generation circuit 274 is an example of an image generation unit. The image generation circuit 274 receives a read image from the imaging device 119 via the image A / D converter 130, and transmits the read image to an information processing device (not shown) via the interface device 138.

  The detection circuit 275 is an example of a detection unit. The detection circuit 275 receives a digital ultrasonic signal from the ultrasonic sensor 115 via the ultrasonic A / D converter 132, and receives a double feed determination threshold from the storage device 150. The detection circuit 275 detects the occurrence of double feeding of the sheet based on the received ultrasonic wave signal and the propagation time, and transmits a detection signal indicating the detection result to the CPU 160.

  The jam determination circuit 276 is an example of a jam determination unit. The jam determination circuit 276 receives a digital audible sound signal from the sound A / D converter 136, determines whether or not a jam occurs based on the received audible sound signal, and outputs a determination signal indicating the determination result. Transmit to CPU 160.

  As described above, the double feed detection device can detect double feed more accurately even when the processing circuit 270 is used.

100 double feed detection device 115a sound wave oscillator 115b ultrasonic wave receiver 161 control unit 162 setting unit 163 correction unit 164 image generation unit 165 detection unit 166 jam determination unit

Claims (9)

A sound wave generator capable of outputting an audible sound and an ultrasonic wave;
An ultrasonic wave receiver disposed opposite to the sound wave generator and outputting an ultrasonic wave signal according to the received ultrasonic wave;
An audible sound receiver that outputs an audible sound signal according to the received audible sound;
A control unit for outputting an audible sound or an ultrasonic wave from the sound wave generator;
A setting unit configured to set a double feed determination threshold based on the audible sound signal;
A detection unit that detects occurrence of double feeding of sheets based on the signal value of the ultrasonic signal and the double feeding determination threshold;
A double feed detection device characterized by having: The frequency of the audible sound is 20 Hz or more and 20 kHz or less,
The double feed detection device according to claim 1, wherein the frequency of the ultrasonic waves is greater than 20 kHz and less than or equal to 300 MHz.   The double feed detection device according to claim 1, further comprising a jam determination unit that determines whether a jam has occurred based on the audible sound signal.   The said setting part estimates the height of the installation place of the said double feeding detection apparatus based on the said audible sound signal, and sets the said double feeding determination threshold based on the said height. The double feed detection device according to one item. A temperature sensor that detects the temperature,
The double feed detection device according to any one of claims 1 to 4, further comprising: a correction unit that corrects the double feed determination threshold based on the temperature. A humidity sensor that detects humidity,
The double feed detection device according to any one of claims 1 to 4, further comprising: a correction unit that corrects the double feed determination threshold based on the humidity.   The double feed detection device according to any one of claims 1 to 6, wherein the control unit causes the sound wave oscillator to output an audible sound at initialization after power-on. An acoustic wave generator capable of outputting an audible sound and an ultrasonic wave, an ultrasonic wave receiver disposed opposite to the acoustic wave wave generator and outputting an ultrasonic wave signal corresponding to the received ultrasonic wave, and an ultrasonic wave corresponding to the received audible sound An audible sound receiver for outputting a hearing signal, the double feed detection method in the double feed detection device,
Generating an audible sound or an ultrasonic wave from the sound wave generator;
Setting a double feed determination threshold based on the audible sound signal;
Based on the signal value of the ultrasonic signal and the double feed determination threshold, it is detected that double feed of paper has occurred;
Method of detecting double feeding, characterized in that An acoustic wave generator capable of outputting an audible sound and an ultrasonic wave, an ultrasonic wave receiver disposed opposite to the acoustic wave wave generator and outputting an ultrasonic wave signal corresponding to the received ultrasonic wave, and an ultrasonic wave corresponding to the received audible sound A control program to be executed by a double feed detection device having an audible sound receiver for outputting a hearing signal.
Generating an audible sound or an ultrasonic wave from the sound wave generator;
Setting a double feed determination threshold based on the audible sound signal;
Based on the signal value of the ultrasonic signal and the double feed determination threshold, it is detected that double feed of paper has occurred;
Control program for causing the double feed detecting device to execute the control program.

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