JP6066410B2 - Paper sheet identification device - Google Patents

Description

  The present invention relates to a paper sheet identification apparatus that performs authenticity determination of paper sheets such as banknotes and cash vouchers.

  In various devices that allow handling of banknotes, such as vending machines, only proper banknotes are accepted based on the authenticity determination of banknotes. Conventionally, the judgment of a banknote is performed based on the printing pattern printed on the banknote, the color of printing, and the like.

  2. Description of the Related Art Conventionally, a banknote recognition apparatus is provided with an optical sensor on a side wall of a banknote transport path provided in the apparatus, and a banknote is transported into a banknote transport path by a transport means such as a belt or a roller. By scanning the banknote, sample information of a plurality of banknotes along the scanning direction is acquired. Furthermore, by arranging a plurality of optical sensors, it is possible to acquire sample information for a plurality of lines, and the accuracy of identifying paper sheets can be improved.

  In addition, by using two colors of red and infrared as the light source used in one scan, scanning is performed while switching the light source in time division, and two types of sample information are acquired in one scan. Improvement of identification accuracy is also performed.

  In such a bill recognition device, the sample information acquired by each light source and line is compared with information corresponding to a regular bill (genuine bill) stored in advance in the bill recognition device by pattern matching, and depending on the magnitude of the difference A screening method for determining authenticity is used.

  Furthermore, as a banknote selection method, there is a method using a frequency analysis technique based on fast Fourier transform as disclosed in Patent Document 1.

  In Patent Document 1, frequency analysis by fast Fourier transform is performed on one-dimensional data parallel to the scanning direction so as not to be affected by changes in temperature and humidity of the linear amplifier circuit due to aging of the light emitting diode and temperature. It is disclosed that, by using this, amplitude information is converted into frequency information, thereby reducing the influence of changes in amplitude information.

JP 2005-92712 A

  At present, there are cases where banknotes copied by a color copier cannot be identified from a genuine note by a conventional identification method (pattern matching) due to an improvement in copying accuracy by a color copier.

As described above, in the pattern matching in the conventional banknote recognition apparatus, by using a plurality of light sensors and light sources of a plurality of colors, for example, 3 lines × 2 light sources = 6 types of data or 5 lines × 2 light sources = 10. The seed data is acquired, and the reference data stored in the apparatus for each acquired data is individually compared to determine the authenticity of the bill. In recent years, higher definition of banknotes has been advanced from the viewpoint of preventing counterfeiting, and improvement of identification accuracy for banknote identification devices is required. Under such circumstances, the technique described in Patent Document 1 described above can discriminate between engraving intaglio printing and dot printing so that high-definition optical information can be obtained to obtain halftone dot information formed by the printing press. It is possible to improve the identification accuracy of banknotes by acquiring optical information with high definition to the extent and identifying based on the acquired information.

  However, such a method for improving identification accuracy requires a higher-definition sensor than before in order to acquire highly accurate optical information. In addition, the amount of information to be acquired is increased, and the amount of processing for determination is increased, so that an increase in memory capacity and a high-performance processor are required. Therefore, it becomes a factor which increases the manufacturing cost of a banknote identification device.

  An object of this invention is to provide the paper sheet identification device which aims at the identification accuracy improvement of the paper sheets containing a banknote, suppressing manufacturing cost.

Therefore, the paper sheet identification apparatus according to the present invention is characterized by the following matters.
A conveying means, a plurality of optical sensor units, and a control means,
The transport means transports paper sheets to be identified,
Each of the optical sensor units is composed of a combination of a light emitting element and a light receiving element, and is arranged in a direction different from the conveying direction of the conveying means,
The control means includes
An acquisition process for acquiring a sample information sequence composed of a plurality of sample information of paper sheets to be identified for each of the optical sensor units while transporting the paper sheets to the transport means;
Integration processing for forming an integrated sample information sequence in which a plurality of sample information sequences are integrated by rearranging the positions of the sample information between the sample information sequences acquired by each of the optical sensor units,
And a determination process for determining the authenticity of the paper sheet to be identified based on the frequency conversion information obtained by frequency-converting the integrated sample information.

Furthermore, in the paper sheet identification apparatus of this embodiment,
The integration process is characterized in that the position of the sample information is rearranged between the sample information strings so that the sample information acquired between the adjacent optical sensor units is arranged.

Furthermore, in the paper sheet identification apparatus of this embodiment,
The light sensor unit irradiates a paper sheet with irradiation light by the light emitting element, receives light transmitted through the paper sheet by the light receiving element, and outputs sample information.

Furthermore, in the paper sheet identification apparatus of this embodiment,
The determination process is characterized by determining the authenticity of the paper sheet to be identified by comparing the peak frequency of the frequency conversion information with the reference information.

Furthermore, in the paper sheet identification apparatus of this embodiment,
The determination process is characterized in that the authenticity of the paper sheet to be identified is determined by comparing the amplitude of the peak frequency of the frequency conversion information with the reference information.

  According to the paper sheet identification device of the present invention, the sample information sequence acquired by the plurality of optical sensor units is rearranged, an integrated sample information sequence is formed, and the integrated sample information sequence is subjected to frequency conversion, whereby paper It becomes possible to acquire frequency conversion information having a feature that can determine whether a leaf is true or false. Therefore, it is possible to improve the identification accuracy while using the same number of sample information strings as in the past. For this reason, it is not necessary to mount a sensor for acquiring high-precision optical information, and it is not necessary to increase the number of sample information or the number of sensors to be used, thereby reducing the manufacturing cost of the paper sheet identification device. It is also possible.

The top view which shows the mode of the banknote conveyance in the paper sheet identification device which concerns on embodiment of this invention. Side sectional view which shows the structure of the paper sheet identification device which concerns on embodiment of this invention The block diagram which shows the control structure of the paper sheet identification device which concerns on embodiment of this invention. The figure which shows the scanning form by the optical sensor part which concerns on embodiment of this invention. The figure which shows sample information (genuine bill) before rearrangement and its frequency conversion information The figure for demonstrating rearrangement of the sample information which concerns on embodiment of this invention The figure for demonstrating the rearrangement of the sample information which concerns on other embodiment of this invention. The figure which shows the sample information after rearrangement, and the frequency conversion information Figure showing sample information before sorting (fake bills made by color printing) Figure showing sample information after sorting (fake bills made by color printing) The figure which shows the frequency conversion information of the sample information after rearranging the genuine note and the counterfeit bill made by color printing The flowchart which shows the identification process in the paper sheet identification device which concerns on embodiment of this invention

  Now, an embodiment of the paper sheet identification apparatus according to the present invention will be described. FIG. 1 is a top view illustrating a state of banknote conveyance in the paper sheet identification apparatus 1 according to the embodiment of the present invention, and a state in which a banknote B to be identified is conveyed to the paper sheet identification apparatus 1. It is shown. FIG. 1 is a top view of the lower configuration of the paper sheet identification device 1. In addition, in the paper sheet identification device according to the present invention, the paper sheet to be identified targets not only such banknotes but also various paper sheets such as various securities such as cash vouchers, securities, and coupons. It is possible.

  In the paper sheet identification apparatus 1, driving rollers 42A to 42D using the banknote B as a conveying unit are provided. The banknote B inserted into the banknote recognition apparatus 1 is sandwiched between the drive rollers 42A to 42D and the opposing rollers 43A to 43D facing each other, and is conveyed leftward in the figure. Is done. In the paper sheet identification apparatus 1, in order to identify the pattern of the banknote B on one of the transport paths that form the transport path of the banknote B, five optical sensor units 20A arranged in a direction orthogonal to the transport direction of the banknote B are used. ˜20E is provided. The five optical sensor units 20A to 20E are respectively arranged at positions corresponding to the characteristic portions in order to detect the characteristic portions at different positions in the width direction of the bill B to be identified.

  The authenticity determination of the banknote B is performed using these five optical sensor units 20A to 20E. FIG. 2 is a side sectional view showing the configuration of the paper sheet identification apparatus 1 according to the embodiment of the present invention. 1 is a cross-sectional view of the paper sheet identification device 1 of FIG. 1 as viewed from the side and cut near the sensor unit 20A. The paper sheet identification device 1 includes a transport unit and an optical sensor unit 20 (the optical sensor units 20A to 20E have the same configuration. Therefore, when any one of the optical sensor units is described below, Symbols A to E are abbreviated.). In addition, it has control means for identifying the authenticity of the paper sheet based on the characteristics of the paper sheet, such as conveying means, control of the optical sensor unit 20, and output from the optical sensor unit 20.

  FIG. 2 shows two drive rollers 42A and 42B. Opposing rollers 43A and 43B are arranged to face the driving rollers 42A and 42B. The driving rollers 42A and 42B are rotated in the direction of the arrow shown by driving means such as a motor. Further, the opposing rollers 43A and 43B are arranged at positions where they come into contact with the driving rollers 42A and 43B, and convey the bill B inserted into the paper sheet identification device 1 in the left direction in the figure.

In the paper sheet identification device 1, a conveyance path through which the bill B passes is formed by two opposed conveyance path walls 11A and 11B. The light emitting element 21 (LED is used in this embodiment) arrange | positioned at the board | substrate 22 is arrange | positioned at one side (conveyance path wall 11B side) of this conveyance path. The light emitting element 21 is disposed such that the light emitting surface thereof faces an opening provided in the transport path wall 11B. Although the light emitting element 21 of this embodiment uses what irradiates one kind of luminescent color, the light emitting element 21 can irradiate a plurality of different luminescent colors, or the optical sensor unit 20 has a plurality of luminescent colors different from each other. The light emitting element 21 may be provided. In the case of irradiating a plurality of emission colors, it is possible to acquire the characteristics of the bill B for each emission color by irradiating the plurality of emission colors in a time-sharing manner.

  On the other side of the transport path (on the transport path wall 11A side), a light receiving element 23 disposed on the substrate 24 is disposed. For the light receiving element 23, a photodetector (PD) capable of detecting the intensity of light and darkness of the transmitted light that has passed through the bill B is used. In the present embodiment, a light receiving element 23 having a frequency region of light emitted from the light emitting element 21 is used. The irradiation light emitted from the light emitting element 21 passes through the bill B conveyed in the conveyance path, is received by the light receiving element 23, and is converted and output as a light reception output signal. The light reception output signal output from the light receiving element 23 is used for feature detection of the bill B by a control means (not shown).

  As described above, the optical sensor unit 20 of the paper sheet identification apparatus 1 according to the present embodiment employs a transmission type that irradiates light on one surface of the bill B and receives transmitted light from the other surface. . In addition to the transmission type, the optical sensor unit 20 may be a reflection type that irradiates one surface of the bill B with light and receives reflected light on the same surface side.

  FIG. 3 is a block diagram showing a control configuration of the paper sheet identification apparatus 1 according to the embodiment of the present invention. The paper sheet identification apparatus 1 according to the present embodiment includes an optical sensor unit 20 including a light emitting element 21 and a light receiving element 23, an amplifier 24 that amplifies a light reception output signal from the optical sensor unit 20, and a control unit 30. Yes. In this control configuration, only one optical sensor unit 20 is shown. However, when the optical sensor unit 20 includes five optical sensor units 20A to 20E as shown in FIG. 1, the control unit 30 includes the optical sensor units 20A to 20A. While controlling the light emission of 20E, the received light reception output signal is input.

  The control unit 30 includes a CPU 31 and a DSP 35. The CPU 31 and the DSP 35 can transmit and receive information via the communication interfaces 34 and 36. The CPU 31 and the DSP 35 are central calculation means in which storage means such as ROM and RAM are integrated, and can execute various calculations based on programs and various data stored in the storage means. In addition, although not shown in figure, this control part 30 controls the drive rollers 42A-42D of a conveyance means, and is conveying the banknote B used as identification object.

  The CPU 31 is further provided with a D / A converter 32 that controls the irradiation light of the light emitting element 21 and an A / D converter 33 that receives the transmitted light of the light receiving element 23 and converts it into sample information. The DSP 35 is provided in order to shorten the time required for the frequency conversion process, and has an FFT calculation unit 37 as frequency conversion means, and performs frequency conversion (FFT: fast Fourier transform) on the sample information acquired by the CPU 31. Conversion) and output frequency conversion information. Based on the frequency conversion information received via the communication interface 34, the CPU 31 performs authenticity determination on the bill B that has been identified.

FIG. 4 is a diagram showing a scanning form by the optical sensor unit 20 according to the embodiment of the present invention. In the paper sheet identification device 1 described with reference to FIGS. 1 and 2, each of the optical sensor units 20A to 20E scans the bill B in the horizontal direction, and the control unit 30 performs sample information U (voltage value) based on the scanning position. Is output. In FIG. 4, each sample information U acquired from each of the optical sensor units 20 </ b> A to 20 </ b> E is indicated by a gray square. For example, 20 A of optical sensor parts located in the uppermost stage output sample information sequence A1 in which a plurality of sample information U was arranged in the horizontal direction of bill B. Similarly, the optical sensor units 20B, 20C, 20D, and 20E output sample information strings A2 to A5, respectively. In the figure, the sample information U in each sample information sequence A is acquired adjacently, but may be acquired in a form in which the pieces of sample information U are separated.

  In the conventional paper sheet identification apparatus, each sample information sequence A1 to A5 thus obtained is subjected to frequency conversion processing such as FFT. FIG. 5A shows sample information strings A1 to A5 for a certain bill B (genuine bill). FIG. 5B shows frequency conversion information A1 to A5 obtained by performing frequency conversion (FFT) on each sample information sequence A1 to A5 of the bill B (genuine bill).

  Each sample information row A1 to A5 in FIG. 5A is a gentle change, but each shows the characteristics of the bill B. On the other hand, looking at the frequency conversion information of FIG. 5B in which each sample information sequence A1 to A5 is frequency converted, since the sample information sequences A1 to A5 are gentle changes, they are aggregated into substantially low frequency components, and banknotes The point which can be used for the authenticity determination of B is lacking. For this reason, since the frequency conversion information which has the characteristic which can be used for the authenticity determination of the banknote B cannot be acquired, authenticity determination cannot be performed.

  In view of such a situation, the paper sheet identification apparatus 1 of the present embodiment uses the sample information strings A1 to A5 of the optical sensor units 20A to 20E acquired in FIG. The frequency conversion information having the characteristics that can be obtained is acquired. For this reason, the acquired sample information sequences A1 to A5 are rearranged as they are to form features for authenticity determination.

  FIG. 6 is a diagram for explaining rearrangement of sample information according to the embodiment of the present invention. FIG. 6 is an enlarged view of the left end described with reference to FIG. 4, and the sample information U is indicated by a gray square as in FIG. The rearrangement is performed in the order of the numbers shown in the squares of the sample information U. In the rearrangement process, the positions of the sample information are rearranged between the sample information strings A1 to A5 to form one integrated sample information. Therefore, this rearrangement can be said to be an integration process for integrating the sample information strings A1 to A5. In this embodiment, the sample information U in the sample information rows A1 to A5 scanned in the horizontal direction of the banknote B is rearranged in the vertical direction (width direction) of the banknote B. In the rearrangement form of FIG. 6, the banknotes B are rearranged in one direction from the upper side to the lower side. However, as shown in FIG. Also good.

  In this embodiment, since the number of sample information U in each sample information sequence A1 to A5 is 60, the integrated sample information sequence formed by the rearrangement includes 300 pieces of sample information U. By performing frequency conversion such as FFT on the integrated sample information sequence, frequency conversion information used for authenticity determination of the bill B is calculated.

  FIG. 8A shows sample information (integrated sample information sequence) after rearrangement, and FIG. 8B shows frequency conversion information obtained by performing frequency conversion on the sample information after rearrangement. is there. As can be seen from FIG. 8A, the integrated sample information sequence is accompanied by periodic fluctuations in the sample information U. Therefore, two large amplitudes that characterize this periodic variation appear in the frequency conversion information in FIG. 8B. These protruding portions will be referred to as a first peak and a second peak, respectively.

  Here, it can be said that the amplitude values of the first peak and the second peak are values obtained by integrating the difference between the sample information U adjacent in the width direction of the bill B. When the bill B to be identified is a genuine note, substantially the same amplitude value. It becomes. Therefore, in this embodiment, the value of the first peak and the second peak is compared with the frequency reference information stored in the storage unit in the CPU 31 in advance. If either one is out of the range of the frequency reference information, it is determined as a fake ticket.

  The comparison between the frequency conversion information and the frequency reference information can be performed by comparing at least one of the peak frequency and the amplitude at the peak frequency. When comparing amplitudes, determination may be made based on the ratio of amplitudes at a plurality of peak frequencies. In such a form, even when characteristics of the optical sensor unit 20 or the like change, such as a change in the intensity of irradiation light of the light emitting element 21, it is possible to perform true / false determination with high accuracy.

  FIG. 9 is a diagram showing a sample information sequence before sorting for counterfeit bills (counterfeits made by color printing), and FIG. 10 rearranges the counterfeit bills (counterfeits made by color printing). It is a figure which shows the later sample information (integrated sample information sequence). When comparing each sample information sequence of the genuine note in FIG. 5A and each sample information sequence of the counterfeit note in FIG. 9, since the counterfeit note is slightly different in transparency, it is simple. Pattern matching is judged to be similar.

  On the other hand, when comparing the integrated sample information sequence of genuine bills shown in FIG. 8A with the integrated sample information sequence of counterfeit bills (fake bills made by color printing) shown in FIG. It can be seen that the periodic amplitude fluctuation of the counterfeit bill made by (1) is smaller than the periodic amplitude fluctuation of FIG. This amplitude variation becomes significant when frequency conversion (FFT: Fast Fourier Transform) is performed on each integrated sample information sequence. FIG. 11 shows the frequency obtained by performing frequency conversion on the integrated sample information sequence of genuine bills shown in FIG. 8A and the integrated information sample sequence of counterfeit bills (fake bills made by color printing) shown in FIG. The characteristic information is shown side by side. In this example, the amplitude of the first peak 1 is clearly different between the genuine note and the counterfeit note. Therefore, it is determined that the (integrated) sample information sequence shown in FIGS. 9 and 10 is a fake ticket.

  FIG. 12 is a flowchart showing the identification processing for identifying the genuine note and the counterfeit note described above in the paper sheet identification apparatus 1 according to the embodiment of the present invention. When detecting that the bill B is inserted into the paper sheet identification device 1, the control unit 30 stores the sample information strings A1 to A5 in the storage means in the CPU 31 acquired based on the optical sensor units 20A to 20E. Is acquired (S101). In addition, in order to improve the identification accuracy of the banknote B, other patterns based on the sample information sequence acquired by each optical sensor unit 20A to 20E or sample information (S102) acquired by a sensor other than the optical sensor units 20A to 20E. The identification process (S200) may be executed.

  In this embodiment, the insertion direction of the banknote B is determined by performing pattern matching on the sample information strings A1 to A5 acquired in S101 (S103). Determination of the insertion direction of the banknote B is good also as performing with sensors other than optical sensor part 20A-20E.

  In S104, reference frequency information serving as a determination reference corresponding to the insertion direction of the bill B determined in S103 is read (S104). The insertion direction of the banknote B is assumed to be four patterns of normal rotation on both the upper and lower sides, upper and lower normal rotation front and back inversion, upper and lower inversion front and back normal rotation, and upper and lower and front and reverse inversion. Accordingly, reference frequency information corresponding to these four patterns is prepared.

  In S105, as described with reference to FIGS. 6 and 7, the sample information sequences A1 to A5 acquired from the respective optical sensor units 20A to 20E are rearranged to perform an integration process for forming an integrated sample information sequence. In S106, frequency conversion information is calculated by performing frequency conversion on the integrated sample information sequence formed in S105. In this embodiment, since FFT (Fast Fourier Transform) is used for frequency conversion, among the sample information U (300 in this embodiment) of the integrated sample information string, a predetermined number (256) suitable for FFT In order to achieve this, it is executed after extracting predetermined sample information U.

  In S107, determination processing for determining the authenticity of the bill B is performed by comparing the frequency conversion information of the integrated sample information sequence calculated in S106 with the reference frequency information read out in S104. The reference frequency information of this embodiment defines the peak frequency and the amplitude of the peak frequency. In S108, the peak frequency is determined, and in S109, it is determined whether the amplitude at the peak frequency is within a predetermined range. Yes. Note that there may be one peak frequency to be determined or a plurality of peak frequencies as described in FIG. When the frequency conversion information does not satisfy even one of the conditions defined by the reference frequency information (S108: No or S109: No), the banknote B as the identification target is determined to be a fake ticket (S112). On the other hand, when all the conditions are satisfied (S108: Yes and S109; Yes), the bill B is determined to be a genuine note (S111). In this case, when the other pattern identification process S200 is executed, the other pattern identification process S200 also needs to be true (S110: Yes).

  As described above, the paper sheet identification device of the present embodiment rearranges the sample information sequences acquired by the plurality of optical sensor units, forms an integrated sample information sequence, and performs frequency conversion on the integrated sample information sequence, It is possible to acquire frequency conversion information having a feature that allows authenticity determination of paper sheets. Therefore, it is possible to improve the identification accuracy while using the same number of sample information strings as in the past. Further, it is not necessary to increase the sample information or increase the number of sensors to be used, and the manufacturing cost of the paper sheet identification device can be suppressed.

  Note that the present invention is not limited to these embodiments, and embodiments configured by appropriately combining the configurations of the respective embodiments also fall within the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 ... Paper sheet identification apparatus 11A, 11B ... Conveyance path wall 20A-20E ... Optical sensor part 21 ... Light emitting element (LED)
22, 24 ... Substrate 23 ... Light receiving element 24 ... Amplifier 30 ... Control unit 31 ... CPU
32 ... D / A converter 33 ... A / D converters 34, 36 ... Communication interface 35 ... DSP
37 ... FFT operation unit 42 ... Driving roller 43 ... Opposite roller B ... Banknote U ... Sample information A1-A5 ... Sample information sequence

Claims (5)

A conveying means, a plurality of optical sensor units, and a control means,
The transport means transports paper sheets to be identified,
Each of the optical sensor units is composed of a combination of a light emitting element and a light receiving element, and is arranged in a direction different from the conveying direction of the conveying means,
The control means includes
An acquisition process for acquiring a sample information sequence composed of a plurality of sample information of paper sheets to be identified for each of the optical sensor units while transporting the paper sheets to the transport means;
Integration processing for forming an integrated sample information sequence in which a plurality of sample information sequences are integrated by rearranging the positions of the sample information between the sample information sequences acquired by each of the optical sensor units,
And a determination process for determining the authenticity of the sheet to be identified based on the frequency conversion information obtained by frequency-converting the integrated sample information. The paper sheet identification according to claim 1, wherein the integration processing rearranges the positions of the sample information between the sample information strings so that the sample information acquired between the adjacent optical sensor units is arranged. apparatus. The light sensor unit irradiates a paper sheet with irradiation light by the light emitting element, receives light transmitted through the paper sheet by the light receiving element, and outputs sample information. The paper sheet identification apparatus according to claim 2. 4. The determination process according to claim 1, wherein the authenticity of the paper sheet to be identified is identified by comparing the peak frequency of the frequency conversion information with reference information. The paper sheet identification device according to 1. 5. The determination process according to claim 1, wherein the authenticity of the paper sheet to be identified is identified by comparing the amplitude of the peak frequency of the frequency conversion information with the reference information. The paper sheet identification apparatus according to Item 1.

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