JP4828882B2 - Authenticity discrimination device for paper sheets - Google Patents

Description

  The present invention relates to the authenticity of a paper sheet for determining the authenticity of a paper sheet such as securities having a printing section printed with ink (for example, pearl ink) that emits glossy or interference color depending on the viewing angle. The present invention relates to a determination device.

Pearl ink is a mica flake coated with a metal oxide such as titanium oxide. Due to its optical structure, it produces gloss and interference colors depending on the viewing angle, like natural pearls. It is characterized by. Since these characteristics are difficult to obtain and reproduce with commercially available color copies and scanners, they are used as one of printing techniques for paper sheets such as securities that require authenticity assurance (for example, patents). Reference 1).
It is difficult to inspect the authenticity of paper sheets with printed parts using pearl ink for the same reason as above, and it is conventionally assumed that the user verifies the authenticity visually on the spot. I have to.
JP 2002-274001 A

  In the case of visual true / false discrimination, it is difficult to make true / false discrimination in large quantities and at high speed. In addition, when the mechanical inspection is realized for the feature, a plurality of signal acquisition units corresponding to a plurality of angles are required, and a complex processing and calculation is required in the signal processing unit. A large-scale configuration is required.

  Therefore, the present invention, for example, for paper sheets having a printing portion made of pearl ink, grasps the infrared optical characteristics of pearl ink in a limited manner, and performs true / false determination with a simple configuration in large quantities and at high speed. An object of the present invention is to provide a paper sheet authenticity discriminating apparatus.

The paper sheet authenticity determination apparatus of the present invention includes an infrared light or an infrared wavelength region with respect to a printing surface of a paper sheet having a printing portion printed with ink that emits glossy or interference color depending on a viewing angle. A light source for irradiating light, first signal acquisition means for receiving transmitted light from the paper sheet by light irradiation of the light source and converting it into an electrical signal, and an electrical signal obtained from the first signal acquisition means A first processing means for obtaining a transmitted light quantity and a transmitted light pattern feature quantity by performing a feature quantity calculation based on the received light, and receiving reflected light from the paper sheet by light irradiation of the light source and converting it into an electrical signal A second signal acquisition unit; a second processing unit that obtains a reflected light amount and a feature amount of a reflected light pattern by performing a feature amount calculation based on an electrical signal obtained from the second signal acquisition unit; The second processing means Each feature amount obtained, and a discriminating means for discriminating the authenticity of the paper sheet by comparing against the reference value of the feature amount obtained in advance, based on authentic data.

  According to the present invention, for example, for paper sheets having a printing portion made of pearl ink, the infrared optical characteristics of pearl ink are limitedly limited, and the true / false determination is made in a large amount and at high speed with a simple configuration. An authenticity determination device for paper sheets can be provided.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
First, the first embodiment will be described.
FIG. 1 schematically shows an example of a paper sheet 10 such as a securities having a printing part with pearl ink according to the present invention, and a printing part 11 having no infrared absorption depending on the type of ink and an infrared absorption. It is assumed that there is a printing unit 12 and further there is a printing unit 13 printed with ink that emits gloss or interference color depending on the viewing angle, for example, pearl ink.

  FIG. 2 schematically shows the configuration of the authenticity determination apparatus for paper sheets according to the first embodiment. The sheets 10 are sequentially conveyed one by one by a conveyance unit 30 as a conveyance unit, and are sequentially sent to the reading position D. The light source 20 and the transmission signal acquisition unit 21 as the first signal acquisition unit are disposed opposite to each other with respect to the reading position D with the conveyance unit 30 interposed therebetween. The light source 20 irradiates one surface of the paper sheet 10 at the reading position D, and the transmission signal acquisition unit 21 receives the transmitted light of the paper sheet 10 at the reading position D and converts it into an electrical signal. In this case, the optical axes of the light source 20 and the transmission signal acquisition unit 21 may not be perpendicular to the conveyance surface of the paper sheet 10.

  The transmission signal acquisition unit 21 is, for example, a line sensor including a plurality of light receiving elements arranged in a line in a direction orthogonal to the conveyance direction of the paper sheet 10, and an electric signal for each line is transmitted to the paper sheet 10. By sequentially acquiring in synchronization with the conveyance, a two-dimensional signal as shown in FIG. 3A is obtained.

  In this case, the light source 20 is a light source that outputs light including an infrared wavelength region, such as a halogen lamp, and a transmission signal acquisition unit 21 is a filter and a sensor that selectively transmit only light in the infrared wavelength region. Thus, an infrared transmission image is acquired.

  Alternatively, the light source 20 is, for example, a light source that emits only light in the infrared wavelength region such as an infrared LED, and the transmission signal acquisition unit 21 is configured by a sensor having sensitivity in a region including light in the infrared wavelength region. In this way, an infrared transmission image can be acquired similarly.

  Similarly, the reflection signal acquisition unit 22 as the second signal acquisition unit is disposed on the same surface side as the light source 20 with respect to the reading position D, and receives the reflected light of the paper sheet 10 at the reading position D. To convert it into an electrical signal. In this case, the reflection signal acquisition unit 22 is not disposed in the regular reflection direction with respect to the reading position D.

  The reflection signal acquisition unit 22 is, for example, a line sensor including a plurality of light receiving elements arranged in a line in a direction orthogonal to the conveyance direction of the paper sheet 10, and an electric signal for each line is transmitted to the paper sheet 10. By sequentially acquiring in synchronization with the conveyance, a two-dimensional signal as shown in FIG. 4A is obtained.

The output signal of the transmission signal acquisition unit 21 is sent to a transmission signal processing unit 23 as a first signal processing unit, and the output signal of the reflection signal acquisition unit 22 is a reflection signal processing unit 24 as a second signal processing unit. Sent to. The transmission signal processing unit 23 performs various feature amount calculations described later based on the electrical signal (transmission light signal) obtained from the transmission signal acquisition unit 21, and the reflection signal processing unit 24 obtains from the reflection signal acquisition unit 22. Based on the electric signal (reflected light signal), various feature amount calculations described later are performed.

  The outputs of the transmission signal processing unit 23 and the reflection signal processing unit 24 are sent to a total processing unit 25 as a total processing unit. The total processing unit 25 further performs one or more processes / calculations, which will be described later, based on the calculation result of the transmitted light signal and the calculation result of the reflected light signal.

  The output of the integrated processing unit 25 is sent to the authenticity determination unit 26 as authenticity determination means. The authenticity determination unit 26 determines the authenticity of the paper sheet based on the processing / calculation results obtained from the general processing unit 25.

Next, the flow of processing according to the first embodiment in such a configuration will be described with reference to the flowchart shown in FIG.
A transmission light signal (transmission image) obtained from the transmission signal acquisition unit 21 with respect to the paper sheet 10 shown in FIG. 1 becomes a transmission image as shown in FIG. 3A, and this transmission image is converted into a transmission input image. Let pt (x, y). In the transmission signal processing unit 23, as shown in FIG. 6A, it is expected that there is a pearl ink printing unit 13 obtained in advance from a genuine paper sheet for the transmission input image pt (x, y). It is assumed that a region E to be printed and a region F expected to have no pearl ink printing unit 13 are set.

  Further, the reflected light signal (reflected image) obtained from the reflected signal acquisition unit 22 with respect to the paper sheet 10 shown in FIG. 1 becomes a reflected image as shown in FIG. 4A, and this reflected image is reflected. Assume that the input image pr (x, y). In the reflected signal processing unit 24, as shown in FIG. 6B, it is expected that there is a pearl ink printing unit 13 obtained from genuine paper sheets in advance for the reflected input image pr (x, y). It is assumed that a region E to be printed and a region F expected to have no pearl ink printing unit 13 are set.

First, the transmission signal processing unit 23 and the reflection signal processing unit 24 perform the calculation shown in the following Equation 1 on the transmission input image pt (x, y) and the reflection input image pr (x, y), thereby obtaining the regions E and The transmission integral values I _TE and I _TF and the reflection integral values I _RE and I _RF of the brightness of the region F are obtained (steps S1 and S2).

Next, the transmission signal processing unit 23 and the reflection signal processing unit 24 perform the calculation shown in the following equation 2 to make the transmission input image pt (x, y) and the reflection input image pr (x, y) authentic. By binarizing the transmission binarized slice level θ _tBIN and the reflection binarized slice θ _rBIN obtained in advance from the paper sheet, the transmission binarized image bt (x, y shown in FIG. 3B) is obtained. ), And converted into a reflected binary image br (x, y) shown in FIG. 4B (steps S3 and S4).

Next, the general processing unit 25 first performs an exclusive OR operation represented by the following Equation 3 on the obtained binarized images bt (x, y) and br (x, y). 7 is converted into a pearl ink print portion extracted image pl (x, y) as shown in FIG. 7 (step S5).

Next, the total processing unit 25 performs a calculation shown in the following equation 4 from each of the previously obtained integral values I _TE , I _TF , I _RE , and I _RF , thereby comparing the value (I _TF −I _TE ). , (I _TE / I _TF ), (I _RF -I _RE ), (I _RE / I _RF ), (I _RE -I _TE ), and (I _TE / I _RE ) are obtained (step S6).

Next, the overall processing unit 25 performs a calculation shown in the following equation 5 to brighten the pearl ink print portion extracted image pl (x, y) obtained in step S5 as shown in FIG. The center of gravity G (Xg, Yg) is obtained (step S7).

Next, the total processing unit 25 performs the calculation shown in the following equation 6 to perform the calculation shown in the following formula 6 on the pearl ink printing unit extracted image pl (x, y) obtained in step S5, and the number of dark pixels (pearl ink printing unit). The number of pixels (area)) A is counted (step S8).

Next, the general processing unit 25 performs a calculation on the pearl ink print portion extracted image pl (x, y) obtained in step S5 as shown in FIG. Patterns Py (x) and Px (y) are obtained (step S9).

Next, the general processing unit 25 performs the calculation shown in the following equation 8 to perform the X direction for the projection patterns Py (x) and Px (y) obtained in step S9 as shown in FIG. The length Lx and the Y direction length Ly are calculated (step S10).

Next, the total processing unit 25 prepares a genuine reference pattern (standard image) r (x, y) of the transmitted light signal in advance, and extracts the pearl ink printing unit extracted image as shown in the following equation (9). Similarity S is calculated by performing pattern matching processing with pl (x, y) (step S11).

Next, the true / false determination unit 26 performs various feature amounts obtained by the transmission signal processing unit 23, the reflection signal processing unit 24, and the total processing unit 25, that is, for example, brightness integrated values I _TE , I _TF , I _RE , I _RF , comparison values (I _TF −I _TE ), (I _TE / I _TF ), (I _RF −I _RE ), (I _RE / I _RF ), (I _RE −I _TE) ), (I _TE / I _RE ), brightness center of gravity G (Xg, Yg), number of pixels (area) A of the pearl ink printing portion, X-direction length Lx, Y-direction length Ly, and similarity S On the other hand, by comparing and collating with the reference value of the same feature obtained in advance based on each authentic data, the appropriateness is determined, and the authenticity determination for the final paper sheet 10 is performed.

Next, a second embodiment will be described.
In the case where paper sheets having a pearl ink printing part are securities, the design of each printing part including the pearl ink printing part shown in FIG. 1 may be determined. It can be realized with a simpler configuration. The second embodiment is applied to such a case.

  FIG. 9 schematically shows the configuration of a paper sheet authenticity determination apparatus according to the second embodiment. The second embodiment is different from the first embodiment (FIG. 2) in that the reflected signal acquisition unit 22, the reflected signal processing unit 24, and the total processing unit 25 are deleted, and the other parts. Since this is the same as in the first embodiment, description thereof is omitted.

Next, the flow of processing according to the second embodiment in such a configuration will be described with reference to the flowchart shown in FIG.
A transmission light signal (transmission image) obtained from the transmission signal acquisition unit 21 with respect to the paper sheet 10 shown in FIG. 1 becomes a transmission image as shown in FIG. 6A, and this transmission image is converted into a transmission input image. Let p (x, y). In the transmission signal processing unit 23, as shown in FIG. 6A, it is expected that there is a pearl ink printing unit 13 obtained in advance from a genuine paper sheet for the transmission input image p (x, y). It is assumed that a region E to be printed and a region F expected to have no pearl ink printing unit 13 are set.

First, the transmission signal processing unit 23 performs the calculation shown in Equation 1 on the transmission input image p (x, y) to obtain the transmission integral values I _E and I _F of the brightness of the region E and the region _F , respectively. Obtained (step S21).

Then, the transmission signal processing unit 23, the integrated value _I E obtained in step S21, the _{I F,} by performing a calculation shown in the following Expression 10, the comparative value _{(I F -I E), (} I E / I _F ) is obtained (step S22).

Next, the transmission signal processing unit 23 performs the calculation shown in Equation 2 above to convert the transmission input image p (x, y) to a transmission binarized slice level θ _BIN obtained in advance from a genuine paper sheet. On the other hand, by binarizing, it is converted into a transmission binary image b (x, y) shown in FIG. 3B (step S23).

  Next, since the pattern of the paper sheet 10 is constant, the transmission signal processing unit 23 has a known area where the pearl ink printing unit is expected, so a mask pattern based on it is prepared in advance. By masking the transmission binarized image b (x, y) selected in step S23, a pearl ink print portion extracted image pl (x, y) is generated (step S24).

  Next, the transmission signal processing unit 23 performs the calculation shown in Equation 5 above, and as shown in FIG. 8, for the pearl ink printing unit extracted image pl (x, y) obtained in step S24, The brightness center of gravity G (Xg, Yg) is obtained (step S25).

  Next, the transmission signal processing unit 23 performs the calculation shown in the above equation 6 to perform the number of dark pixels (pearl ink printing) on the pearl ink printing unit extracted image pl (x, y) obtained in step S24. The number of pixels (area) A is counted (step S26).

  Next, the transmission signal processing unit 23 performs the calculation shown in Equation 7 above, and as shown in FIG. 8, for the pearl ink printing unit extracted image pl (x, y) obtained in step S24, Projection patterns Py (x) and Px (y) are obtained (step S27).

  Next, the transmission signal processing unit 23 performs the calculation shown in Equation 8 above, so that the projection patterns Py (x) and Px (y) obtained in Step S27 are each X as shown in FIG. The direction length Lx and the Y direction length Ly are calculated (step S28).

  Next, the transmission signal processing unit 23 prepares a genuine reference pattern (standard image) r (x, y) of the transmission light signal in advance, and extracts the pearl ink printing unit as in the calculation shown in Equation 9 above. Similarity S is calculated by performing pattern matching processing with the image pl (x, y) (step S29).

Next, the authenticity determination unit 26 performs various feature amounts obtained by the transmission signal processing unit 23, that is, for example, brightness integration values I _E and I _F , and comparison values (I _F −I) of the integration values. _E ), (I _E / I _F ), brightness center of gravity G (Xg, Yg), number of pixels (area) A of the pearl ink printing portion, X-direction length Lx, Y-direction length Ly, and similarity S On the other hand, by comparing and collating with the reference value of the same feature obtained in advance based on the respective authentic data, the appropriateness is determined, and the authenticity determination for the final paper sheet 10 is performed.

  Thus, in addition to the features described above, the pearl ink is characterized by a large amount of reflected light and a small amount of transmitted light in the near-infrared light region. Therefore, in the above embodiment, a transmission optical system having sensitivity in the near-infrared light region or both optical means of the transmission optical system and the reflection optical system are configured, and the transmitted light signal or transmission of the obtained paper sheet is obtained. The presence / absence of pearl ink characteristics is determined by detecting the difference in light quantity and pattern for both the optical signal and the reflected light signal, and the authenticity of the paper sheet is determined. As a result, for paper sheets having a printing portion made of pearl ink, the infrared optical characteristics of pearl ink can be grasped in a limited manner, and authenticity can be determined in large quantities and at high speed with a simple configuration. .

The transmission signal acquisition unit 21 and the reflection signal acquisition unit 22 acquire a one-dimensional signal with a single light receiving element disposed at a position where the pearl ink printing unit 13 of the paper sheet 10 passes at the reading position D. It is good.
Alternatively, the transmission signal acquisition unit 21 and the reflection signal acquisition unit 22 may be area sensors (cameras) that can acquire the entire area of the paper sheet 10 or a part of the two-dimensional signal without the transport unit 30.
Further, each feature amount extraction process described above is an embodiment, and is not limited to this example. Each arithmetic expression is also a general expression for explanation, and is limited by this arithmetic expression. Is not to be done.
In addition, the present invention can be used as a complementary function of a large-scale authenticity determination device having a plurality of authenticity determination functions even if it is used as a simple and simple authenticity determination device for paper sheets. May be.

  Furthermore, in the above embodiment, the case of determining the authenticity of paper sheets such as securities having a printing part printed with pearl ink has been described, but the present invention is not limited to this, The present invention can be similarly applied to the determination of the authenticity of paper sheets such as securities having a printing section printed with ink having characteristics similar to pearl ink.

The schematic diagram which shows an example of paper sheets, such as securities, which has the printing part by the pearl ink which concerns on this invention. The schematic diagram which shows schematically the structure of the authenticity determination apparatus of the paper sheets concerning the 1st Embodiment of this invention. The figure which shows an example of the permeation | transmission image with respect to the paper sheets of FIG. The figure which shows an example of the reflective image with respect to the paper sheets of FIG. 1, and a reflective binarized image. The flowchart explaining the flow of the process which concerns on 1st Embodiment. The figure explaining the example of a region setting with respect to a transmission image and a reflection image. The figure which shows an example of a pearl ink printing part extraction image. The figure which shows an example of the projection pattern with respect to the pearl ink printing part extraction image of FIG. The schematic diagram which shows schematically the structure of the authenticity determination apparatus of the paper sheets concerning the 2nd Embodiment of this invention. The flowchart explaining the flow of the process which concerns on 2nd Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Paper sheets (securities), 11 ... Printing part without infrared absorption, 12 ... Printing part with infrared absorption, 13 ... Printing part printed with pearl ink, 30 ... Conveying part (conveying means), D: Reading position, 20: Light source, 21: Transmission signal acquisition unit (first signal acquisition unit), 22: Reflection signal acquisition unit (second signal acquisition unit), 23: Transmission signal processing unit (first signal) Processing means), 24... Reflection signal processing section (second signal processing means), 25... Comprehensive processing section (total processing means), 26.

Claims (4)

A light source that irradiates infrared light or light including an infrared wavelength region on a printing surface of a paper sheet having a printed portion printed with ink that emits gloss or interference color depending on a viewing angle;
First signal acquisition means for receiving transmitted light from the paper sheet by light irradiation of the light source and converting it into an electrical signal;
First processing means for obtaining a transmitted light amount and a feature quantity of a transmitted light pattern by performing a feature quantity calculation based on an electrical signal obtained from the first signal acquisition means ;
Second signal acquisition means for receiving reflected light from the paper sheet by light irradiation of the light source and converting it into an electrical signal;
Second processing means for obtaining a reflected light amount and a reflected light pattern feature quantity by performing a feature quantity calculation based on the electrical signal obtained from the second signal acquisition means ;
Discriminating means for discriminating the authenticity of the paper sheet by comparing each feature quantity obtained from the first and second processing means with a reference value of the feature quantity obtained in advance based on authentic data. When,
An apparatus for discriminating authenticity of paper sheets, comprising: Transport means for sequentially transporting the paper sheets to a reading position;
Said first and second signal acquisition means according to claim 1 authenticity discrimination device of the sheet of, wherein the sequentially acquiring the electrical signal in synchronization with the conveyance of the paper sheet at the reading position . The first and second signal acquisition means are composed of a plurality of light receiving elements arranged in a line in a direction orthogonal to the conveyance direction of the paper sheet at the reading position, authenticity discriminating apparatus of a sheet according to claim 1, wherein the obtaining a two-dimensional signal by sequentially obtained in synchronization with the conveyance of the paper sheet. The viewing angle by luster and interference color authenticity discrimination device of the sheet of claim 1 wherein is that the pearl ink and ink that emits.

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