JP4788270B2 - Paper sheet counting apparatus and paper sheet inspection system using the same - Google Patents

Description

  The present invention relates to a paper sheet counting device that counts the number of accumulated paper sheets, and a paper sheet inspection system that uses a plurality of the paper sheet counting devices to inspect paper sheets for bending or damage. .

  2. Description of the Related Art Conventionally, a paper sheet counting device that counts the number of accumulated paper sheets from the capacitance of the paper sheets is known (see Patent Document 1 below).

  In such an apparatus, the stacked paper sheets are sandwiched between a pair of counter electrodes, and the capacitance of the paper sheets is measured. The number of sheets can be calculated by an arithmetic process using the measurement result (see, for example, paragraph 0011 and FIG. 1 in Patent Document 1).

  However, in the paper sheet counting device of Patent Document 1, since it is necessary to sandwich the electrode from both ends of the paper sheet, the restriction on the installation position of the paper sheet counting device becomes large. For example, when this paper sheet counting apparatus is accommodated in some paper sheet processing apparatus, the electrode installation space must be secured facing both sides of the accommodated paper sheet.

  In addition, in the paper sheet counting apparatus of Patent Document 1, the detection accuracy greatly depends on the relative position of the counter electrode. That is, even if one of the counter electrodes is slightly displaced, the reliability of the detection result is greatly reduced. For this reason, in the paper sheet counting apparatus disclosed in Patent Document 1, it is not possible to dispose the counter electrode in a portion that is likely to be displaced, such as a movable part in the paper sheet processing apparatus.

For this reason, the paper sheet counting apparatus of Patent Document 1 has a great design restriction when mounted on a paper sheet processing apparatus, which hinders cost reduction and downsizing of the paper sheet processing apparatus. There were drawbacks.
JP 2004-149245 A

  An object of the present invention is to provide a paper sheet counting apparatus with less restrictions on installation space and installation position.

  (1) The first invention relates to a paper sheet counting apparatus for detecting the number of paper sheets from the capacitance of the paper sheets.

  A transmission electrode disposed on the paper sheet placement surface to radiate electromagnetic waves from the surface to the paper sheet, and a placement surface for receiving the electromagnetic waves emitted from the transmission electrode via the paper sheet. In order to cut off the current flowing between the transmitting electrode and the shield electrode, and the receiving electrode arranged, the shield electrode arranged facing the transmitting electrode to cut off the electromagnetic wave radiated from the back surface of the transmitting electrode A sensor unit having an auxiliary electrode disposed between these electrodes, a buffer circuit for supplying an alternating voltage generated by an oscillator to the transmission electrode and the auxiliary electrode, and a detection current as a voltage between terminals A first wiring for connecting the output terminal of the buffer circuit and the transmission electrode via the current detection resistance element, and an output terminal of the buffer circuit and the auxiliary electrode without using the current detection resistance element. Connect And a second wiring.

  (2) A paper sheet inspection system according to a second aspect of the present invention relates to a transmission electrode disposed on a paper sheet placement surface in order to radiate an electromagnetic wave from a surface to a paper sheet, and an electromagnetic wave radiated by the transmission electrode. A receiving electrode disposed on the mounting surface for receiving via a paper sheet, a shield electrode disposed opposite to the transmitting electrode to shield electromagnetic waves radiated from the back surface of the transmitting electrode, and the transmitting electrode A sensor unit having an auxiliary electrode disposed between these electrodes in order to cut off a current flowing between the shield electrode and the shield electrode, and an AC voltage generated by an oscillator for supplying the transmitter electrode and the auxiliary electrode A buffer circuit, a current detection resistor element for detecting the detection current as a voltage between terminals, a first wiring connecting the output terminal of the buffer circuit and the transmission electrode via the current detection resistor element, and a current detection resistor element Buffer without intervention A plurality of paper sheet counting devices having a second wiring for connecting the output terminal of the road and the auxiliary electrode so that the sensor unit of the paper sheet counting device can simultaneously measure the number of the same paper sheets. And a determination circuit that determines the coincidence / non-coincidence by comparing the number of sheets detected by each of the sheet counting devices.

  (1) According to the paper sheet counting apparatus according to the first aspect of the present invention, the transmitting electrode and the receiving electrode can be provided on the same paper sheet mounting surface, so that both sides of the accommodated paper sheet face each other. It is not necessary to secure an electrode installation space. In addition, since both the transmission electrode and the reception electrode can be arranged on the same mounting surface, there is no possibility that the relative positions of the transmission electrode and the reception electrode will be shifted. There is no worsening. Furthermore, since the shield electrode and the auxiliary electrode are provided, the detection accuracy does not deteriorate even if a metal or the like is disposed on the back side of the transmission electrode. Therefore, according to the paper sheet counting apparatus according to the first aspect of the present invention, it is possible to provide a paper sheet counting apparatus with less design restrictions on installation space and arrangement position.

  (2) According to the paper sheet inspection system according to the second invention, using a plurality of paper sheet counting devices of the first invention, the number of the same paper sheets is simultaneously measured at different positions, and these The measurement results can be compared. Thereby, according to the paper sheet inspection system which concerns on 2nd invention, the presence or absence of the bending of this paper sheet or damage can be detected.

  Embodiments of the present invention will be described below with reference to the drawings. In the drawings, the size, shape, and arrangement relationship of each component are shown only schematically to the extent that the present invention can be understood, and the numerical conditions described below are merely examples. .

First Embodiment Hereinafter, an embodiment of a paper sheet counting apparatus according to the present invention will be described with reference to FIGS.

  FIG. 1 is a circuit diagram schematically showing the configuration of the paper sheet counting apparatus according to this embodiment.

  As shown in FIG. 1, the paper sheet counting apparatus 100 according to this embodiment includes a sensor unit 101, an oscillation circuit 102, a buffer circuit 103, a current detection resistor element 104, a shield cable 105, and a first difference. Dynamic amplifier 106, band pass filter 107, detector circuit 108, low pass filter 109, second differential amplifier 110, analog / digital converter 111, CPU (Central Processing Unit) 112, and digital / analog conversion And a container 113.

  The sensor unit 101 includes a transmission electrode 101a, a reception electrode 101b, a shield electrode 101c, and an auxiliary electrode 101d. The transmission electrode 101a is disposed on the paper sheet placement surface in order to radiate electromagnetic waves to the paper sheet from the surface. The receiving electrode 101b is disposed on the same mounting surface as the transmitting electrode 101a in order to receive the electromagnetic wave radiated from the transmitting electrode 101a via a paper sheet. The shield electrode 101c is an electrode for shielding electromagnetic waves radiated from the back surface side of the transmission electrode 101a. The auxiliary electrode 101d is an electrode for cutting off the current flowing between the transmission electrode 101a and the shield electrode 101c. In this embodiment, the auxiliary electrode 101d is provided between the transmission electrode 101a and the shield electrode 101c, and an alternating voltage is supplied to the transmission electrode 101a and the auxiliary electrode 101d via different wirings. Detection accuracy can be improved (described later). As shown in FIG. 1, the receiving electrode 101b and the shield electrode 101c are grounded.

  The oscillation circuit 102 generates and outputs an AC voltage for causing the transmission electrode 101a to emit an electromagnetic wave. In the following description, the oscillation frequency of the oscillation circuit 102 is assumed to be f [Hz].

  The buffer circuit 103 is a buffer that supplies the AC voltage output from the oscillation circuit 102 to the sensor unit 101. As shown in FIG. 1, in this embodiment, the buffer circuit 103 is configured by one voltage follower circuit. That is, in this embodiment, AC voltage is supplied to the transmission electrode 101a and the auxiliary electrode 101d by the same voltage follower circuit. Thereby, it is possible to suppress the error factor caused by the fluctuation on the output side of the buffer circuit 103 and improve the detection accuracy of the paper sheet (described later).

  The current detection resistance element 104 is a resistance element for converting a current flowing through the sensor unit 101 into a voltage (described later). The current detection resistor element 104 is connected between the output terminal of the buffer circuit 103 and the shield cable 105.

  The shielded cable 105 supplies the AC voltage output from the buffer circuit 103 to the sensor unit 101. The shielded cable 105 has a core wire 105a and a covered wire 105b. One end of the core wire 105 a is connected to the output end of the buffer circuit 103 via the resistance element 104. The other end of the core wire 105a is connected to the transmission electrode 101a. One end of the covered wire 105 b is directly connected to the output end of the buffer circuit 103 without going through the resistance element 104. The other end of the covered wire 105b is connected to the auxiliary electrode 101d.

  The first differential amplifier 106 is a measurement amplifier, and both the non-inverting input terminal (+) and the inverting input terminal (−) have high input impedance, and a voltage corresponding to the potential difference between the non-inverting input terminal and the inverting input terminal. Is output. A non-inverting potential terminal of the differential amplifier 106 is connected to one end of the resistance element 104 (that is, the end on the buffer circuit 103 side). The inverting input terminal of the differential amplifier 106 is connected to the other end of the resistance element 104 (that is, the end portion on the transmission electrode 101a side). Therefore, the differential amplifier 106 outputs an AC voltage signal having a value corresponding to the voltage across the resistance element 104. As will be described later, the current flowing through the resistance element 104 depends on the number of sheets placed on the electrodes 101a and 101b, and therefore the voltage between the terminals of the resistance element 104 also varies depending on the number of sheets. .

The band-pass filter 107 is a signal component (frequency f) of the input AC voltage signal (
That is, only the component having the same frequency as that of the oscillation circuit 102 is passed. This band pass filter 107 can remove noise components from the AC voltage signal output from the differential amplifier 106. For example, when a noise source such as a motor is disposed in the vicinity of the paper sheet counting apparatus 100, noise may be mixed into the AC voltage signal due to electromagnetic waves generated by the motor or the like, which may cause false detection. Such a noise is removed by the band pass filter 107.

  The detection circuit 108 converts the input AC voltage signal into a DC voltage signal. In this embodiment, a full-wave rectifier circuit having a time constant τ set to about 1 / f is used as the detection circuit 108 (f is the output frequency of the oscillation circuit 102). FIG. 4 is a waveform diagram conceptually showing the relationship between the time constant of the detection circuit 108 and the output signal, where A is the input signal waveform, B is the output signal waveform when the time constant τ is 1 / f, and C is It is an output signal waveform when the time constant τ is very large. Here, the input signal waveform A shows a case where the noise component An is mixed in the original signal waveform. As can be seen from FIG. 4, when the time constant τ is very large, a flat output signal waveform (that is, an output signal waveform with a small ripple component) C with small fluctuation can be obtained when the original input signal waveform is input. However, when the noise component An is input, the output signal level is maintained at the noise level. On the other hand, when the time constant τ is about 1 / f, an output signal waveform (that is, an output signal waveform having a large ripple component) B having a large fluctuation when the original input signal waveform is input becomes a noise component. When An is input, the influence of the noise is small. Here, the ripple component can be removed by providing a low-pass filter after the detection circuit 108. For this reason, in this embodiment, the time constant τ is set to about 1 / f and the low-pass filter 109 is provided in the subsequent stage.

  The low pass filter 109 removes high frequency components from the input signal. This low-pass filter 109 can remove a ripple component from the DC voltage signal output from the detection circuit 108.

  The second differential amplifier 110 outputs a voltage corresponding to the potential difference between the non-inverting input terminal (+) and the inverting input terminal (−). The non-inverting input terminal of the differential amplifier 110 is connected to the output terminal of the low-pass filter 109. The inverting input terminal of the differential amplifier 110 is connected to the output terminal of the digital / analog converter 113. As will be described later, the differential amplifier 110 corrects the output signal of the detection circuit 108 so that the value when the sheets are not placed on the electrodes 101a and 101b becomes zero. The DC voltage signal output from the differential amplifier 110 is output to the outside as the detection signal Sd.

  The analog / digital converter 111 converts the DC voltage signal (that is, the detection signal Sd) output from the differential amplifier 110 from an analog signal to a digital signal.

  The CPU 112 generates a correction signal Sa by performing arithmetic processing using a predetermined algorithm on the digital signal input from the analog / digital converter 111, stores the correction signal Sa inside, and outputs the correction signal Sa to the digital / analog converter 113. As will be described later, the detection signal Sd is corrected by the correction signal Sa.

  The digital / analog converter 113 converts the output signal of the CPU 112 from a digital signal to an analog signal.

  2 and 3 are conceptual views showing the configuration of the sensor unit 101, FIG. 2 is a sectional view, and FIG. 3 is an exploded perspective view.

  As shown in FIGS. 2 and 3, the sensor unit 101 has a printed circuit board 201. On the surface of the printed board 201, a metal thin film as the transmission electrode 101a and a metal thin film as the reception electrode 101b are printed. A metal thin film as the auxiliary electrode 101d is printed on the back surface of the printed circuit board 201 at a position facing the transmission electrode 101a. For this reason, the base material 202 of the printed circuit board 201 serves as a dielectric of a capacitor formed by the transmission electrode 101a and the auxiliary electrode 101d. As the base material 202, for example, a Teflon (registered trademark) plate having a thickness of 0.2 to 0.4 mm can be used. In addition, it is not necessary to provide an electrode in the part which opposes the receiving electrode 101b among the back surfaces of the printed circuit board 201. FIG.

  For example, a metal plate, conductive rubber, conductive cloth, or the like can be used as the shield electrode 101c.

  The auxiliary electrode 101d and the shield electrode 101c are fixed via a spacer 203. The spacer 203 is used to fix the auxiliary electrode 101d and the shield electrode 101c at a predetermined uniform interval. For this reason, the spacer 203 is bonded to the auxiliary electrode 101d and the shield electrode 101c using an adhesive or the like (not shown). The spacer 203 is formed of an insulating material (for example, resin). As shown in FIG. 3, the spacer 203 is formed in a lattice shape, and the hollow portion 203a passes therethrough. This hollow portion 203a becomes an insulating layer of the capacitor formed by the auxiliary electrode 101d and the shield electrode 101c. If the height d1 of the spacer 203 is too small, the capacitance of the capacitor becomes too large. In addition, the thickness d2 (see FIG. 3) of the lattice portion is determined so as to obtain an area necessary for bonding the spacer 203 and the electrodes 101b and 101c with sufficient strength.

  Next, the operation principle of the paper sheet counting apparatus 100 according to this embodiment will be described with reference to FIGS. 5A is a conceptual diagram showing a case where no paper sheet is placed on the placement surface of the sensor unit 101, and FIG. It is a conceptual diagram which shows the case where it exists.

  First, the operation principle of the initial adjustment of the paper sheet counting apparatus 100 will be described with reference to FIGS. 1 and 5A. This adjustment is performed when paper sheets are not placed on the placement surface of the sensor unit 101.

  When no paper sheet is placed on the placement surface of the sensor unit 101, the capacitance Ca between the electrodes 101a and 101b is given by the space on the placement surface. Further, as described above, a capacitance Cb is provided between the transmission electrode 101a and the auxiliary electrode 101d by the base material 202 of the printed circuit board 201, and the spacer 203 is provided between the auxiliary electrode 101d and the shield electrode 101c. Capacitance Cc is given by the hollow portion 203a (see FIG. 3).

  When the buffer circuit 103 starts outputting an AC voltage, this AC voltage is applied to the transmission electrode 101 a via the core wire 105 a of the shielded cable 105. As described above, the capacitor having the capacitance Ca is connected to the transmission electrode 101a. For this reason, a minute current having a value corresponding to the capacitance Ca flows between the transmission electrode 101a and the reception electrode 101b.

Further, the AC voltage output from the buffer circuit 103 is also applied to the auxiliary electrode 101 d via the covered wire 105 b of the shield cable 105. As described above, a capacitor having a capacitance Cc is connected to the auxiliary electrode 101d. Therefore, a current I ₁ having a value corresponding to the capacitance Cc of these capacitors and the output (frequency f and voltage E) of the buffer circuit 103 is supplied from the buffer circuit 103 to the auxiliary electrode 101d.

Due to the voltage drop when the current I ₁ flows through the covered wire 105b, the potential of the auxiliary electrode 101d decreases. Therefore, a potential difference is generated between the transmission electrode 101a and the auxiliary electrode 101d. Therefore, the current I ₀ flows from the transmission electrode 101a to the auxiliary electrode 101d via the capacitor having the electrostatic capacitance Cb. As described above, the current flowing into the transmission electrode 101a is the sum of the current supplied to the capacitor having the capacitance Ca and the current I ₀ supplied to the capacitor having the capacitance Cb. The current I ₀ is supplied from the buffer circuit 103 to the transmission electrode 101a via the resistance element 104. Accordingly, a potential difference is generated at both ends of the resistance element 104 due to a voltage drop of the current I ₀ .

  The differential amplifier 106 outputs an AC voltage signal corresponding to this potential difference. This voltage signal has its noise component removed by the band-pass filter 107, converted from an AC signal to a DC signal by the detection circuit 108, and after the ripple component has been removed by the low-pass filter 109, the non-inverting input terminal of the differential amplifier 110 (See FIG. 1). The differential amplifier 110 outputs a voltage corresponding to the difference between the DC signal and the correction signal Sa as a detection signal Sd.

  Here, in order to obtain sufficient detection accuracy when the sensor unit 101 detects the number of sheets, the signal value when there is no sheet is set to a predetermined value (here, zero volts). It is desirable to correct the detection signal Sd. This correction is performed by the CPU 112 or the like as follows.

  The detection signal Sd is digitized by the analog / digital converter 111 and sent to the CPU 112. The CPU 112 calculates the difference between the actual signal value of the digital detection signal Sd and the target value (here, zero volts) by a predetermined algorithm, stores the calculation result inside, and also outputs the digital / value as the value of the correction signal Sa. Send to analog converter 113. The digital / analog converter 113 changes the output voltage to a value corresponding to the correction signal Sa. As a result, the value of the signal supplied to the inverting input terminal of the differential amplifier 110 is changed. In this way, the input voltage of the inverting input terminal becomes the same as the input voltage of the non-inverting input terminal (that is, the output signal value of the low-pass filter), and the output of the differential amplifier 110 becomes zero volts.

  Next, the principle of operation when the number of sheets is detected by the sheet counting apparatus 100 will be described with reference to FIGS. 1 and 5B.

  As described above, before the paper sheet is placed on the placement surface of the sensor unit 101, the capacitance Ca of the electrodes 101a and 101b is given by the space on the placement surface. The current flowing through the electrodes 101a and 101b when the paper sheet 502 is not placed is canceled as described above.

On the other hand, when the paper sheet 502 is mounted on the mounting surface, the capacitance (here, Cs) of the electrodes 101a and 101b is given by the paper sheet 502. In general, since the relative dielectric constant of the paper is about 2 to 4, Ca <Cs is satisfied, and the capacitance increases by placing the paper sheet 502. For this reason, when the paper sheet 502 is mounted on the mounting surface, the current flowing between the electrodes 101a and 101b increases. Here, the increased current value is assumed to be I ₀ . That is, when placing the paper sheet 502 on the mounting surface of the sensor section 101, current flowing through the resistor element 104 increases from I ₀ to I ₀ + I _s. For this reason, the potential difference between the terminals of the resistance element 104 also increases, and thereby the output of the differential amplifier 106 also increases.

As described above, the differential amplifier 106 outputs an AC voltage signal corresponding to the potential difference between the terminals of the resistance element 104. This voltage signal has its noise component removed by the band-pass filter 107, converted from an AC signal to a DC signal by the detection circuit 108, and after the ripple component has been removed by the low-pass filter 109, the non-inverting input terminal of the differential amplifier 110 Is input. The differential amplifier 110 outputs a voltage corresponding to the difference between the DC signal and the correction signal Sa as a detection signal Sd. Here, the correction signal Sa is set so that the detection signal Sd becomes zero volts when the paper sheet 502 does not exist (that is, when the current I ₀ flows through the resistance element 104) (described above). . Therefore, the detection signal Sd has a value corresponding to the current I _s flowing through the sheet 502.

The capacitance Cs of the paper sheet 502 increases in accordance with the number of the paper sheets 502. Therefore, the current _Is also increases according to the number of sheets 502, and therefore the potential difference between the terminals of the resistance element 104 also increases according to the number of sheets 502. The number of sheets 502 placed on the unit 101 can be detected.

  For this reason, the paper sheet counting apparatus according to this embodiment can detect the number of paper sheets 502.

  As described above, in this embodiment, the auxiliary electrode 101d is provided between the transmission electrode 101a and the shield electrode 101c, and an alternating current is transmitted from one buffer circuit 103 to the transmission electrode 101a and the auxiliary electrode 101d via different wires. It was decided to supply voltage. Therefore, the detection accuracy for the paper sheet 502 can be increased for the following reason.

  First, the reason why one buffer circuit 103 is used will be described.

  As shown in FIG. 1, in the paper sheet counting apparatus 100 of this embodiment, the sensor unit 101 and the electronic circuit portion (circuits 102 to 104 and 106 to 113) are connected by a shielded cable 105. For this reason, when the sensor unit 101 and the electronic circuit part are installed apart from each other, the shielded cable 105 may be close to another part of the apparatus on which the paper sheet counting apparatus 100 is mounted. Here, when the shielded cable 105 and the grounded metal are close to each other, a capacitance (here, CL) is generated between the metal and the covered wire 105b. Accordingly, when an AC voltage is supplied from the buffer circuit 103 to the covered wire 105b, a current (here, IL) flows from the covered wire 105b to the metal. For this reason, the capacitance CL becomes a load of the buffer circuit 103. In general, when a capacitive load increases in an operational amplifier, an output phase delay with respect to an input increases. For this reason, when an alternating voltage is supplied to the transmission electrode 101a and the auxiliary electrode 101d from separate voltage follower circuits, a phase difference occurs between the alternating voltages supplied to these electrodes 101a and 101d, A potential difference is generated between the electrodes 101a and 101d. For this reason, the current flowing through the resistance element 104 due to the capacitance CL increases. Here, if the value of the capacitance CL is constant, the influence of this current is eliminated by the correction signal Sa (see FIG. 1). However, when the value of the capacitance CL is not constant (that is, when a component close to the shielded cable 105 is a movable component), the variation in the capacitance CL causes a detection error. On the other hand, when an AC voltage is supplied to the transmission electrode 101a and the auxiliary electrode 101d from the same buffer circuit 103, the transmission electrode 101a and the auxiliary electrode 101d There is no phase difference between the two. For this reason, the detection accuracy of paper sheets can be improved by using one buffer circuit 103.

  Next, the reason why the auxiliary electrode 101d is provided and the reason why an AC voltage is supplied to the transmission electrode 101a and the auxiliary electrode 101d via different wirings will be described.

  Originally, the sensor unit 101 detects the paper sheet only in the surface direction of the transmission electrode 101a. However, actually, electromagnetic waves are also emitted in the direction of the back surface of the transmission electrode 101a. Therefore, even when other components are present in the back surface direction of the transmission electrode 101a, it is necessary to prevent an electric field from being formed between the components and the transmission electrode 101a. When an electric field is formed between a component or the like in the rear surface direction and the transmission electrode 101a, the current flowing through the resistance element 104 varies due to a change in the position of the component or the like, causing false detection or deterioration in detection accuracy. Because it becomes. For this reason, a grounded shield electrode 101c is provided on the back surface side of the transmission electrode 101a. However, when only the shield electrode 101c is provided (that is, when the auxiliary electrode 101d is not provided), a current flows between the transmission electrode 101a and the shield electrode 101c. Normally, the capacitance between the transmission electrode 101a and the shield electrode 101c is very large compared to the capacitance between the transmission electrode 101a and the paper sheet, and therefore, the transmission electrode 101a and the shield electrode 101c. The current flowing between the transmitting electrode 101a and the paper sheet is also very large compared to the current flowing between the transmitting electrode 101a and the paper sheet. For this reason, when a current flows between the transmission electrode 101a and the shield electrode 101c, it becomes very difficult to accurately detect the current between the transmission electrode 101a and the paper sheet. On the other hand, when the auxiliary electrode 101d is provided between the transmission electrode 101a and the shield electrode 101c and the potentials of these electrodes 101a and 101c are set to substantially the same potential, the components existing on the back side of the transmission electrode 101a, etc. It is possible to keep the current flowing on the back side very small while eliminating the influence.

  In addition, in this embodiment, an AC voltage is supplied to the transmission electrode 101a and the auxiliary electrode 101d via different wirings, and the resistance element 104 is provided on the wiring connecting the buffer circuit 103 and the transmission electrode 101a. . That is, the transmission electrode 101 a is connected to the buffer circuit 103 via the core wire 105 a of the shielded cable 105 and the resistance element 104, and the auxiliary electrode 101 d is connected to the buffer circuit 103 via the covered wire 105 b of the shielded cable 105. Thus, the current flowing through the transmission electrode 101a and the current flowing through the auxiliary electrode 101d are separated, and the current flowing through the auxiliary electrode 101d does not flow through the resistance element 104. For this reason, the current flowing through the resistance element 104 can be reduced, and therefore the detection accuracy of the current flowing out from the transmission electrode 101a to the paper sheet is improved.

  FIG. 6 is a graph showing the relationship between the number of paper sheets placed on the placement surface of the sensor 101 and the detection signal Sd. In FIG. 6, the horizontal axis represents the number of paper sheets, and the vertical axis represents the voltage value of the detection signal Sd. As can be seen from FIG. 6, in the paper sheet counting apparatus 100 according to this embodiment, the number of paper sheets and the detection signal Sd have a linear relationship, and the paper sheets can be accurately detected in units of one sheet. .

  As described above, according to the paper sheet counting apparatus 100 according to this embodiment, the transmission electrode 101a and the reception electrode 101b can be provided on the same surface of the printed circuit board 201, so that both sides of the paper sheet are opposed to each other. Thus, there is no need to secure an electrode installation space, and there is no possibility that the relative positions of the electrodes 101a and 101b shift. Therefore, the paper sheet counting apparatus 100 according to this embodiment has small design restrictions when mounted on another apparatus, and it is easy to reduce the cost and size of the apparatus.

  Further, the paper sheet counting apparatus 100 according to this embodiment supplies an AC voltage from one buffer circuit 103 to the transmission electrode 101a and the auxiliary electrode 101d via different wires, so that the transmission electrode 101a to the paper sheet. The flowing current can be detected with high accuracy, and therefore the influence of other components and the like mounted on the same apparatus as the paper sheet counting apparatus 100 can be suppressed, and the paper sheet detection accuracy can be improved. .

  Furthermore, in the paper sheet counting apparatus 100 according to this embodiment, the detection signal Sd when the paper sheet is detected is corrected using the detection signal value when the paper sheet is not detected. The detection accuracy of leaves can be further improved.

Second Embodiment Next, an embodiment of the paper sheet inspection system according to the present invention will be described with reference to FIGS.

  FIG. 7 is a schematic diagram showing the configuration of the paper sheet inspection system according to this embodiment.

  As shown in FIG. 7, the paper sheet inspection system 700 of this embodiment includes two paper sheet counting devices 710 and 720 and a determination circuit 730.

  The paper sheet counting device 710 includes a sensor 711, a shield cable 712, and a detection circuit 713. The sensor 711 is the same as the sensor unit 101 in the first embodiment. The shielded cable 712 is the same as the shielded cable 105 in the first embodiment. The detection circuit 713 is the same as the electronic circuit portion of the paper sheet counting apparatus 100 (a circuit constituted by the elements 102 to 104 and 106 to 113). From the sheet counting device 710, a detection signal Sd1 indicating the number of sheets is output.

  The paper sheet counting device 720 includes a sensor 721, a shield cable 722, and a detection circuit 723. The sensor 721 is also the same as the sensor unit 101 in the first embodiment. The shielded cable 722 is also the same as the shielded cable 105 in the first embodiment. The detection circuit 713 is also the same as the electronic circuit portion of the paper sheet counting apparatus 100. From the sheet counting device 720, a detection signal Sd2 indicating the number of sheets is output.

  The determination circuit 730 receives the detection signals Sd1 and Sd2 from the detection circuits 713 and 723 and compares them. When the number of sheets indicated by the detection signals Sd1 and Sd2 matches, it is determined that the state of the paper sheet is normal. On the other hand, when the number of detection signals Sd1 and Sd2 does not match, it is determined that the paper sheet is damaged or bent.

  Note that the sensor 711 and the sensor 721 are installed so that the placement surface is horizontal in order to simultaneously place a set of paper sheet bundles.

  In this embodiment, it is desirable to determine the dimensions and arrangement positions of the sensors 711 and 721 so that each of the sensors 711 and 721 contacts approximately half of the sheet bundle. By making the contact area between the sheet bundle and the sensors 711 and 721 as large as possible and making the contact area between the sheet bundle and each sensor 711 and 721 approximately the same, the accuracy of detecting bending and damage can be improved. It is because it improves.

  Next, the operation principle of the paper sheet inspection system 700 will be described with reference to FIG. 8A is a conceptual diagram illustrating a case where the paper sheet is normal, and FIG. 8B is a conceptual diagram illustrating a case where the paper sheet is bent.

  First, in the same manner as in the first embodiment described above, initial adjustment of the paper sheet counting devices 710 and 720 is performed. Subsequently, the sheet bundle 810 is placed so as to straddle the placement surfaces of the sensors 711 and 721. Thereafter, in the same manner as in the first embodiment, the paper sheet counting devices 710 and 720 independently detect the number of paper sheets. As a result, the detection signals Sd1 and Sd2 are output from the paper sheet counting devices 710 and 720 to the determination circuit 730.

  The determination circuit 730 compares the detection signals Sd1 and Sd2. Here, when the detection signal Sd1 and the detection signal Sd2 match (when the number of detected sheets matches), the determination circuit 730 determines that the paper sheet is normal (see FIG. 8A). Then, the determination circuit 730 outputs the determination result that is normal together with the number of sheets as a determination signal Sc.

  On the other hand, when the detection signal Sd1 and the detection signal Sd2 do not match, there is a high possibility that a part of the sheet bundle is bent or damaged. For example, when the sheet 812 placed is bent in two, the detection signals Sd1 and Sd2 have a difference of two sheets (see FIG. 8B). Further, when the right half or the left half is damaged with respect to one sheet placed, the detection signals Sd1 and Sd2 have a difference corresponding to one sheet. Therefore, when the number of detection signals Sd1 and the number of detection signals Sd2 do not match, the determination circuit 730 determines that the sheet is abnormal and outputs a determination result to that effect as the determination signal Sc. To do.

  With the operation as described above, the paper sheet inspection system 700 according to this embodiment can inspect whether the paper sheet is bent or damaged.

  In this embodiment, the paper sheets are inspected using the two paper sheet counting devices 710 and 720. However, the inspection may be performed using three or more paper sheet counting devices. Good. This makes it easier to detect small bends and damage.

  In this embodiment, the sensors 711 and 721 are separately manufactured independently. However, the sensors 711 and 721 may be manufactured integrally using a single substrate.

It is a circuit diagram showing roughly the composition of the paper sheet counting device concerning a 1st embodiment. It is sectional drawing which shows schematically the structure of the paper sheet counting device which concerns on 1st Embodiment. It is an exploded perspective view showing roughly the composition of the paper sheet counting device concerning a 1st embodiment. It is a voltage waveform diagram for demonstrating operation | movement of the paper sheet counting device which concerns on 1st Embodiment. It is a conceptual diagram for demonstrating operation | movement of the paper sheet counting device which concerns on 1st Embodiment. It is a graph for demonstrating the effect of the paper sheet counting device which concerns on 1st Embodiment. It is a conceptual diagram which shows the structure of the paper sheet inspection system which concerns on 2nd Embodiment. It is a conceptual diagram for demonstrating operation | movement of the paper sheet inspection system which concerns on 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Paper sheet counting device 101 Sensor part 102 Oscillation circuit 103 Buffer circuit 104 Current detection resistive element 105 Shield cable 106 1st differential amplifier 107 Band pass filter 108 Detection circuit 109 Low pass filter 110 2nd differential amplifier 111 Analog / digital conversion 112 CPU
113 Digital / analog converter

Claims (6)

A paper sheet coefficient device for detecting the number of paper sheets from the capacitance of the paper sheets,
A transmitting electrode disposed on a surface of the paper sheet to radiate electromagnetic waves from the surface to the paper sheet; and a front electrode for receiving the electromagnetic wave radiated by the transmitting electrode through the paper sheet. A receiving electrode disposed on the mounting surface; a shield electrode disposed opposite the transmitting electrode to shield electromagnetic waves emitted from the back surface of the transmitting electrode; and between the transmitting electrode and the shielding electrode A sensor part having an auxiliary electrode arranged between these electrodes in order to interrupt the current flowing through
A buffer circuit for supplying an alternating voltage generated by an oscillator to the transmission electrode and the auxiliary electrode;
A current detection resistance element for detecting the detection current as a voltage between the terminals;
A first wiring that connects the output terminal of the buffer circuit and the transmission electrode via the current detection resistor element;
A second wiring that connects the output terminal of the buffer circuit and the auxiliary electrode without passing through the current detection resistor element;
A paper sheet counting apparatus comprising: A first differential amplifier that outputs a voltage corresponding to the voltage between the terminals of the current detection resistor element;
A detection circuit for converting an output signal of the first differential amplifier into a DC signal;
A second differential amplifier that inputs an output signal of the detection circuit from one input terminal and outputs a detection signal from the output terminal;
An arithmetic processor for supplying a correction signal generated based on the value of the detection signal when the paper sheet is not placed on the placement surface to the other input terminal of the second differential amplifier;
The paper sheet counting apparatus according to claim 1, further comprising: The transmitting electrode and the receiving electrode are conductive thin films printed adjacent to a surface of a printed circuit board;
The auxiliary electrode is a conductive thin film printed on the back surface of the printed circuit board,
The shield electrode is a conductive plate bonded on the auxiliary electrode via a spacer;
The paper sheet counting apparatus according to claim 1 or 2, characterized in that A transmitting electrode disposed on a surface of the paper sheet to radiate electromagnetic waves from the surface to the paper sheet; and a front electrode for receiving the electromagnetic wave radiated by the transmitting electrode through the paper sheet. A receiving electrode disposed on the mounting surface; a shield electrode disposed opposite the transmitting electrode to shield electromagnetic waves emitted from the back surface of the transmitting electrode; and between the transmitting electrode and the shielding electrode A sensor part having an auxiliary electrode arranged between these electrodes in order to interrupt the current flowing through
A buffer circuit for supplying an alternating voltage generated by an oscillator to the transmission electrode and the auxiliary electrode;
A current detection resistance element for detecting the detection current as a voltage between the terminals;
A first wiring that connects the output terminal of the buffer circuit and the transmission electrode via the current detection resistor element;
A second wiring that connects the output terminal of the buffer circuit and the auxiliary electrode without passing through the current detection resistor element;
A plurality of paper sheet counting devices comprising
The sensor units of the paper sheet counting device are arranged so as to be able to simultaneously measure the number of the same paper sheets, and
A determination circuit that compares the number of the paper sheets detected by each of the paper sheet counting devices and determines whether the paper sheets match or not is provided.
Paper sheet inspection system characterized by that. Each of the paper sheet counting devices is
A first differential amplifier that outputs a voltage corresponding to the voltage between the terminals of the current detection resistor element;
A detection circuit for converting an output signal of the first differential amplifier into a DC signal;
A second differential amplifier that inputs an output signal of the detection circuit from one input terminal and outputs a detection signal from the output terminal;
An arithmetic processor for supplying a correction signal generated based on the value of the detection signal when no paper sheet is placed on the placement surface to the other input terminal of the second differential amplifier;
The paper sheet inspection system according to claim 4, further comprising: In each of the paper sheet counting devices,
The transmitting electrode and the receiving electrode are conductive thin films printed adjacent to a surface of a printed circuit board;
The auxiliary electrode is a conductive thin film printed on the back surface of the printed circuit board,
The shield electrode is a conductive plate bonded on the auxiliary electrode via a spacer;
The paper sheet inspection system according to claim 4 or 5.

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