JP2022129805A - Paper sheet identification apparatus and paper sheet identification method - Google Patents

Abstract

To provide a paper sheet identification apparatus, a paper sheet identification method, and a paper sheet identification program capable of improving paper sheet identification accuracy.SOLUTION: A paper sheet identification apparatus for identifying a paper sheet provided with an identification target, comprises: a light source for irradiating a paper sheet with light; a light receiving unit for receiving light coming from the paper sheet; and a control unit for acquiring output data of the light receiving unit. The control unit acquires first data that is output data of the light receiving unit corresponding to an area including the identification target and second data that is output data of the light receiving unit corresponding to an area not including the identification target, generates third data where the first data is corrected by the second data, and identifies the paper sheet based on the third data.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to a paper sheet identification device, a paper sheet identification method, and a paper sheet identification program.

2. Description of the Related Art In a paper sheet identification device for identifying paper sheets such as bills, various sensors are used to acquire characteristics of paper sheets. Then, based on the characteristics of the obtained paper sheet, it is generally performed to identify (determine) the type (denomination), authenticity, fitness, etc. of the paper sheet.

For example, Patent Literatures 1 and 2 disclose an optical sensor that irradiates a bill with infrared light of multiple wavelengths from a light source and receives the light reflected or transmitted by the bill with a light receiving portion.

WO2019/082251 WO2020/208806

However, there are variations in the characteristics of light emitting elements (e.g., LEDs) of the light source, shifts in peak wavelength due to temperature, and fluctuations in the transmittance of light guides (e.g., acrylic resin light guides) according to the wavelength of the light source. The output data of the light-receiving unit may vary due to environmental factors. In such a case, paper sheet identification processing is performed based on the output data with variations, so the paper sheet identification accuracy is lowered. In addition, since variations in the output data due to environmental factors tend to be particularly noticeable in the infrared region, when paper sheet identification processing is performed based on the output data in the infrared region, the accuracy is particularly high. easily exacerbated.

In the case of irradiating bills with light of multiple wavelengths and identifying paper sheets based on the output data of light of multiple wavelengths acquired from the light receiving unit, identification is performed using only the output data of light of each wavelength. Although processing is generally performed, the performance of separating the authenticity of an identification target (for example, special ink) provided on the paper sheet may not be sufficient. Insufficient performance in separating the authenticity of an object to be identified leads to a decrease in accuracy in identifying the paper sheet.

The present disclosure has been made in view of the above-mentioned current situation, and aims to provide a paper sheet identification device, a paper sheet identification method, and a paper sheet identification program capable of improving the accuracy of paper sheet identification. It is intended.

In order to solve the above-described problems and achieve the object, (1) a paper sheet identification device according to a first aspect of the present disclosure provides paper sheet identification for identifying a paper sheet provided with an identification target object; A device comprising: a light source for irradiating light onto a paper sheet; a light receiving unit for receiving light coming from the paper sheet; and a control unit for acquiring output data of the light receiving unit, wherein the control unit is , acquiring first data that is output data of the light receiving unit corresponding to an area including an identification object, and second data that is output data of the light receiving unit corresponding to an area not including the identification object; Then, the third data is generated by correcting the first data with the second data, and the paper sheets are identified based on the third data.

(2) In the paper sheet identification device described in (1) above, the light source may irradiate the paper sheet with light of a plurality of wavelengths, and the light receiving section may emit light of a plurality of wavelengths coming from the paper sheet. Light may be received, the first data and the second data may each include data relating to the light of the plurality of wavelengths, and the control unit receives the first data relating to the light of the plurality of wavelengths. Third data related to a plurality of wavelengths may be generated, each of which is corrected by second data related to light of the same corresponding wavelength, and paper sheets are identified based on the third data related to light of the multiple wavelengths. good too.

(3) In the paper sheet recognition apparatus described in (2) above, the control unit controls the data related to the light of the first wavelength and the light of the second wavelength among the first data related to the light of the plurality of wavelengths. and the second data obtained by multiplying the data related to the light of the first wavelength and the light of the second wavelength out of the second data related to the light of the plurality of wavelengths multiplication data may be calculated, and fourth data may be generated by correcting the first multiplication data using the second multiplication data; You may identify paper sheets based on.

(4) In the paper sheet identification apparatus according to any one of (1) to (3) above, the control unit uses, as the second data, a representative value of output data of an area that does not include the identification object. may be used.

(5) In the paper sheet identification device according to any one of (1) to (4) above, the light source includes a rod-shaped light guide made of acrylic resin and one of the two end faces of the light guide. and a light emitting element facing at least one side, and the light source may irradiate the paper sheet with light through the light guide.

(6) In the paper sheet identification device according to any one of (1) to (5) above, the light source may irradiate the paper sheet with linear light in a main scanning direction, The light-receiving unit may receive linear light in the main scanning direction coming from paper sheets, and the control unit receives, as the second data, the position of the area containing the identification object in the main scanning direction. You may use the output data according to.

(7) A paper sheet identification device according to a second aspect of the present disclosure is a paper sheet identification device that identifies a paper sheet provided with an identification target, and irradiates the paper sheet with light of a plurality of wavelengths. a light source for irradiation, a light receiving unit for receiving light of multiple wavelengths coming from paper sheets, and a control unit for acquiring output data related to the light of multiple wavelengths from the light receiving unit, wherein the control unit comprises: Multiplying data obtained by multiplying the data of the light of the first wavelength and the data of the light of the second wavelength out of the obtained output data of the light of the plurality of wavelengths, and calculating the output data of the light of the plurality of wavelengths. and the multiplication data.

(8) In the paper sheet identification device according to any one of (1) to (7) above, the light source may irradiate the paper sheet with infrared light, and the infrared light has a wavelength of 850 nm or more. , 950 nm or less.

(9) In the paper sheet identification device according to any one of (1) to (8) above, the light receiving unit may receive light emitted from the light source and reflected by the paper sheet, The output data may include data relating to light reflected by the paper sheet.

(10) In the paper sheet identification device according to any one of (1) to (9) above, the paper sheet to be identified has a reflectance that decreases as the wavelength in the infrared region increases as the identification target. and at least one of ink whose reflectance increases as the wavelength in the infrared region increases.

(11) A paper sheet identification method according to a third aspect of the present disclosure is a paper sheet identification method for identifying a paper sheet provided with an identification target, wherein the paper sheet is irradiated with a light source and A step (A) of acquiring output data from a light receiving unit that receives the incoming light; first data that is output data of the light receiving unit corresponding to a region that includes an identification target; and first data that does not include the identification target. a step (B) of acquiring second data that is output data of the light receiving section corresponding to the area; a step (C) of generating third data by correcting the first data using the second data; and a step (D) of identifying paper sheets based on the third data.

(12) In the paper sheet identification method described in (11) above, the light source may irradiate the paper sheet with light of a plurality of wavelengths, and the light receiving unit may emit light of a plurality of wavelengths coming from the paper sheet. Light may be received, the first data and the second data may each include data relating to the light of the plurality of wavelengths, and in step (C), the first data relating to the light of the plurality of wavelengths may be received. The data may be corrected with the corresponding second data of the light of the same wavelength to generate the third data of the plurality of wavelengths, and in step (D) above, the third data of the light of the plurality of wavelengths is converted to the third data of the plurality of wavelengths. You may identify paper sheets based on.

(13) In the paper sheet identification method according to (12) above, the data obtained by multiplying the data related to the light of the first wavelength and the data related to the light of the second wavelength out of the first data related to the light of the plurality of wavelengths Calculation of certain first multiplication data and second multiplication data obtained by multiplying the data relating to light of the first wavelength and the second data relating to the light of the plurality of wavelengths by each other The step (C) may further include generating fourth data by correcting the first multiplication data with the second multiplication data, and the step (D) may include: Paper sheets may be identified based on the third data and the fourth data relating to the light of the plurality of wavelengths.

(14) In the paper sheet identification method according to any one of (11) to (13) above, in step (C), output data of an area that does not contain the identification object is used as the second data. A representative value may be used.

(15) In the paper sheet identification method according to any one of (11) to (14) above, the light source includes a rod-shaped light guide made of acrylic resin and one of the two end faces of the light guide. and a light emitting element facing at least one side, and the light source may irradiate the paper sheet with light through the light guide.

(16) In the paper sheet identification method according to any one of (11) to (15) above, the light source may irradiate the paper sheet with linear light in a main scanning direction, The light-receiving unit may receive linear light in the main scanning direction coming from the paper sheet, and in step (C), as the second data, You may use the output data according to the position of .

(17) A paper sheet identification method according to a fourth aspect of the present disclosure is a paper sheet identification method for identifying a paper sheet provided with an identification target, wherein the paper sheet is irradiated with a light source and a step of acquiring output data relating to the light of the plurality of wavelengths from a light receiving unit that has received the light of the plurality of wavelengths; a step of calculating multiplication data obtained by multiplying the data relating to the light of the plurality of wavelengths; and a step of identifying the paper sheet based on the output data relating to the light of the plurality of wavelengths and the multiplication data.

(18) In the paper sheet identification method according to any one of (11) to (17) above, the light source may irradiate the paper sheet with infrared light, and the infrared light has a wavelength of 850 nm or more. , 950 nm or less.

(19) In the paper sheet identification method according to any one of (11) to (18) above, the light receiving unit may receive light emitted from the light source and reflected by the paper sheet, The output data may include data relating to light reflected by the paper sheet.

(20) In the paper sheet identification method according to any one of (11) to (19) above, the paper sheet to be identified has a reflectance that decreases as the wavelength in the infrared region increases as the identification target. and at least one of ink whose reflectance increases as the wavelength in the infrared region increases.

(21) A paper sheet identification program according to a fifth aspect of the present disclosure is a paper sheet identification program for identifying a paper sheet provided with an identification target using a paper sheet identification device, A process (A) for acquiring output data from the light receiving unit that receives the light emitted from the paper sheet and received from the first data that is the output data of the light receiving unit corresponding to the area including the identification target; a process (B) for acquiring second data, which is output data of the light-receiving unit corresponding to an area that does not include the identification object; and third data obtained by correcting the first data using the second data. The paper sheet identifying apparatus is caused to execute the process (C) for generating and the process (D) for identifying the paper sheet based on the third data.

(22) In the paper sheet identification program described in (21) above, the light source may irradiate the paper sheet with light of a plurality of wavelengths, and the light receiving unit may emit light of a plurality of wavelengths coming from the paper sheet. Light may be received, the first data and the second data may each include data relating to the light of the plurality of wavelengths, and in the process (C), the first data relating to the light of the plurality of wavelengths may be received. The data may be corrected with the corresponding second data of the light of the same wavelength to generate the third data of the plurality of wavelengths, and in the process (D), the third data of the light of the plurality of wavelengths You may identify paper sheets based on.

(23) In the paper sheet identification program according to (22) above, the data obtained by multiplying the data related to the light of the first wavelength and the data related to the light of the second wavelength out of the first data related to the light of the plurality of wavelengths Calculation of certain first multiplication data and second multiplication data obtained by multiplying the data relating to light of the first wavelength and the second data relating to the light of the plurality of wavelengths by each other The processing (D) may further include processing (D), wherein the processing (C) may generate fourth data by correcting the first multiplication data with the second multiplication data, and the processing (D) may include: Paper sheets may be identified based on the third data and the fourth data relating to the light of the plurality of wavelengths.

(24) In the paper sheet identification method according to any one of (21) to (23) above, in the process (C), as the second data, the output data of the area not including the identification object. A representative value may be used.

(25) In the paper sheet identification program according to any one of (21) to (24) above, the light source includes a rod-shaped light guide made of acrylic resin and one of the two end surfaces of the light guide. and a light emitting element facing at least one side, and the light source may irradiate the paper sheet with light through the light guide.

(26) In the paper sheet identification program according to any one of (21) to (25) above, the light source may irradiate the paper sheet with linear light in a main scanning direction, The light-receiving unit may receive linear light in the main scanning direction coming from paper sheets. You may use the output data according to the position of .

(27) A paper sheet identification program according to a sixth aspect of the present disclosure is a paper sheet identification program for identifying a paper sheet provided with an identification target using a paper sheet identification device, a process of acquiring output data relating to the light of the plurality of wavelengths from the light receiving unit that received the light of the plurality of wavelengths emitted from the paper sheet and the output data relating to the light of the plurality of wavelengths acquired; a process of calculating multiplication data, which is data obtained by multiplying data relating to light of a first wavelength and a second wavelength; and a process of identifying the paper sheet identification device.

(28) In the paper sheet identification program according to any one of (21) to (27) above, the light source may irradiate the paper sheet with infrared light, and the infrared light has a wavelength of 850 nm or more. , 950 nm or less.

(29) In the paper sheet identification program according to any one of (21) to (28) above, the light receiving unit may receive light emitted from the light source and reflected by the paper sheet, The output data may include data relating to light reflected by the paper sheet.

(30) In the paper sheet identification method according to any one of (21) to (29) above, the paper sheet to be identified has a reflectance that decreases as the wavelength in the infrared region increases as the identification target. and at least one of ink whose reflectance increases as the wavelength in the infrared region increases.

According to the present disclosure, it is possible to provide a paper sheet identifying device, a paper sheet identifying method, and a paper sheet identifying program capable of improving the accuracy of paper sheet identification.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram for explaining an example of the configuration of a paper sheet identification device according to Embodiment 1, and is a diagram of a banknote transport path as seen from the side; FIG. 2 is a schematic plan view showing an example of banknotes to be identified according to the first embodiment; 4 is an example of a graph showing reflectance in the infrared region of ink provided on a banknote to be identified according to Embodiment 1. FIG. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram illustrating an example of the configuration of a paper sheet identification device according to Embodiment 1, and is a diagram viewed from an oblique direction; BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram illustrating an example of the configuration of a paper sheet identifying apparatus according to Embodiment 1, and is a view of a banknote transport path as seen from above; It is a schematic diagram which shows the image data of the whole banknote. 4 is a flowchart for explaining an example of the operation of the paper sheet identification device according to the first embodiment; FIG. 10 is a schematic diagram illustrating an example of the configuration of a paper sheet identification device according to Embodiment 2, and is a diagram of a banknote transport path as seen from the side. FIG. 11 is a schematic plan view showing an example of banknotes to be identified according to the second embodiment; FIG. 10 is a schematic diagram illustrating an example of the configuration of a paper sheet identification device according to Embodiment 2, and is a diagram viewed from an oblique direction; FIG. 10 is a schematic diagram illustrating an example of the configuration of a paper sheet identifying apparatus according to Embodiment 2, and is a view of a banknote transport path as seen from above. 9 is a flowchart for explaining an example of the operation of the paper sheet identification device according to the second embodiment; FIG. 12 is a schematic perspective view showing the appearance of an example of a paper sheet processing apparatus in which the paper sheet identifying apparatus according to Embodiment 3 can be mounted; FIG. 11 is a block diagram illustrating an example of the configuration of a paper sheet identification device according to Embodiment 3; FIG. 11 is a schematic cross-sectional view illustrating an example of the configuration of an optical line sensor included in the paper sheet identification device according to Embodiment 3;

Hereinafter, embodiments of a paper sheet identifying device, a paper sheet identifying method, and a paper sheet identifying program according to the present disclosure will be described with reference to the drawings. Various paper sheets such as bills, checks, gift certificates, bills, forms, securities, and card-like media can be applied as the paper sheets that are the subject of this disclosure. The present disclosure will be described by taking an apparatus as an example. Note that the paper sheet identification program may be installed in the paper sheet identification apparatus in advance, recorded in a computer-readable recording medium, or provided to the operator via a network. Further, in the following description, the same reference numerals are appropriately used for the same parts or parts having similar functions in different drawings, and repeated description thereof will be omitted as appropriate. In addition, XYZ coordinate systems orthogonal to each other are appropriately shown in the drawings for explaining the structure.

(Embodiment 1)
The configuration of the paper sheet identification device according to the present embodiment will be described with reference to FIG. FIG. 1 is a schematic diagram for explaining an example of the configuration of the paper sheet identification device according to the present embodiment, and is a view of the banknote conveyance path as seen from the side. As shown in FIG. 1, the paper sheet identification device 1a according to the present embodiment includes a light source 11a that irradiates light onto the banknote BN, a light receiving unit 13a that receives light coming from the banknote BN, and an output of the light receiving unit 13a. and a control unit 20a for acquiring data. The bill BN to be identified may be conveyed in the X direction within the XY plane.

FIG. 2 is an example of a schematic plan view showing an example of banknotes to be identified in the present embodiment. FIG. 3 is an example of a graph showing the reflectance in the infrared region of the ink provided on the bill to be identified according to the present embodiment. As shown in FIG. 2, an identification object S is provided (for example, printed) on at least one main surface of the banknote BN to be identified in this embodiment. For example, a rectangular region ROI _A containing the identification object S and, for example, a rectangular region ROI _B not containing the identification object S are set on the main surface of the banknote BN.

As shown in FIG. 3, the banknotes BN to be identified are composed of ink whose reflectance decreases as the wavelength increases in the infrared region (hereinafter referred to as negative ink) and ink with a longer wavelength in the infrared region. It may contain at least one of ink whose reflectance increases as it becomes thicker (hereinafter referred to as positive ink). According to the paper sheet identification device 1a, it is possible to identify such banknotes BN containing ink with high accuracy. Hereinafter, negative ink and positive ink may be collectively referred to as special ink. In FIG. 3, IR1 is, for example, 800 nm, IR2 is, for example, 870 nm, and IR3 is 940 nm.

The light source 11a irradiates the bill BN with light. The light emitted by the light source 11a may be light in a wavelength band including the peak wavelength and its neighboring wavelengths. The type (wavelength) of the light emitted from the light source 11a is not particularly limited, and includes visible light such as white light, red light, green light, and blue light, infrared light, and the like.

The light receiving unit 13a receives light coming from the bill BN. That is, it can function as an optical sensor. The light receiving unit 13a may receive the light emitted from the light source 11a and reflected by the bill BN. That is, while the light source 11a emits light, the light receiving unit 13a may receive the light reflected by the bill BN. At this time, the light receiving section 13a can function as a sensor sensitive to at least the wavelength band of the light emitted from the light source 11a. The light receiving section 13a may output an electrical signal corresponding to the amount of light received as output data. More specifically, the light-receiving section 13a may include a light-receiving element, the light-receiving element may receive light and convert it into an electrical signal corresponding to the amount of incident light, and the light-receiving section 13a may convert the electrical signal into may be output. Here, the term "light quantity" means a physical quantity proportional to the radiant intensity and incident time of incident light.

FIG. 4 is a schematic diagram illustrating an example of the configuration of the paper sheet identification device according to the present embodiment, and is a diagram viewed from an oblique direction. As shown in FIG. 4, the light source 11a and the light receiving section 13a may constitute an optical line sensor 14a extending in the Y direction. In this case, the Y direction corresponds to the main scanning direction of the optical line sensor 14a, and the X direction corresponds to the sub scanning direction of the optical line sensor 14a. The light source 11a may emit light in a straight line extending in the Y direction. The light-receiving section 13a may include a plurality of light-receiving elements (light-receiving pixels) arranged in a row in the Y direction, and may constitute a linear image sensor.

Also, the lengths of the light source 11a and the light receiving section 13a in the Y direction (main scanning direction) may be longer than the length of the bill BN in the Y direction. The light source 11a may linearly irradiate the banknote BN in the Y direction, and the light receiving unit 13a may receive the light reflected in the banknote BN in the entire Y direction. That is, the light receiving section 13a may output electrical signals corresponding to the amount of incident light on a plurality of channels corresponding to a plurality of light receiving elements (positions in the Y direction). A channel is a number assigned to the light receiving elements in order in the Y direction. At this time, the light receiving section 13a may output, as the output data, line data, which is data relating to light received simultaneously in each channel. By repeating the light irradiation by the light source 11a and the light reception by the light receiving unit 13a while conveying the banknote BN in the X direction (sub-scanning direction), it is possible to acquire data related to the reflected light of the entire banknote BN. good.

FIG. 5 is a schematic diagram for explaining an example of the configuration of the paper sheet identifying apparatus according to the present embodiment, and is a view of the banknote transport path from above. As shown in FIG. 5, the light source 11a may include a light guide 15a and light emitting elements 17a facing two end surfaces 15aa of the light guide 15a. BN may be irradiated with light.

The light guide 15a is a transparent, rod-shaped optical member that guides the light from the light emitting element 17a and irradiates the banknote BN, which is an irradiation target, with linear light. Linearize the light.

The light guide 15a may be made of acrylic resin. Since the light guide 15a made of acrylic resin has a great influence on the output data of the light receiving section 13a, in this case, it is possible to particularly effectively reduce variations in the first data described later. Therefore, it is possible to improve the identification accuracy of banknotes BN particularly effectively.

The light emitting element 17a is an element that emits light toward the opposing end surface 15aa, and for example, an LED (Light Emitting Diode) can be used. A plurality of light emitting elements 17a may be provided for corresponding end faces. Alternatively, the light emitting element 17a may be arranged to face only one of the two end surfaces 15aa.

The light source 11a may irradiate the bill BN with infrared light including light with a wavelength of 850 nm or more and 950 nm or less. The transmittance of the light guide 15a (for example, a light guide made of acrylic resin) of the light source 11a fluctuates particularly in the infrared region around 900 nm. first data) can be reduced. Therefore, it is possible to improve the identification accuracy of banknotes BN particularly effectively. Further, it is possible to highly accurately identify banknotes BN that include ink (for example, special ink) whose reflectance varies in the infrared region around 900 nm as the identification object S.

Each light-receiving pixel of the light-receiving section 13a may include a light-receiving element having sensitivity over a plurality of different wavelength bands, or may include a plurality of types of light-receiving elements that selectively receive light in different wavelength bands. may be In the former case, the light source 11a may sequentially irradiate the banknote BN with light of a plurality of wavelengths, and the light receiving section 13a may receive the light of each wavelength in accordance with the irradiation timing of the light of each wavelength. In the latter case, the light source 11a may simultaneously irradiate the banknote BN with light of multiple wavelengths, and the light receiving section 13a may receive light of multiple wavelengths with multiple types of light receiving elements.

The control unit 20a performs a process of acquiring output data from the light receiving unit 13a. That is, data corresponding to the amount of light received by the light receiving section 13a is acquired. The output data of the light receiving unit 13a acquired by the control unit 20a may be digitized. The control unit 20a may acquire image data of the entire bill BN as the output data of the light receiving unit 13a.

FIG. 6 is a schematic diagram showing image data of the entire bill. The image data of the entire banknote BN is data (two-dimensional data) obtained by imaging the entire banknote BN, and as shown in FIG. Pix may be composed of a plurality of pixels Pix. The address of each pixel Pix may be specified by the channel of the light receiving section 13a corresponding to the position in the Y direction and the line corresponding to the position in the X direction. A line is a number assigned in order to line data sequentially output from the light receiving unit 13a.

The output data of the light receiving unit 13a acquired by the control unit 20a may include data related to light reflected by the bill BN. As a result, it is possible to highly accurately identify banknotes BN that include ink (for example, special ink) with characteristic reflectance as the identification object S.

Further, the control unit 20a may acquire image data related to the reflected light of the entire banknote BN as the output data of the light receiving unit 13a. Image data related to reflected light is hereinafter referred to as reflected image data.

The resolution of the output data acquired by the control unit 20a may be the same as or different from the resolution of the output data of the light receiving unit 13a. sub-scanning direction).

The control unit 20a may control each unit of the paper sheet recognition apparatus 1a. For example, the control unit 20a includes a program for realizing various processes including a paper sheet recognition program, and a CPU for executing the program. (Central Processing Unit) and various hardware (for example, FPGA (Field Programmable Gate Array)) controlled by the CPU.

The control unit 20a controls the first data, which is the output data of the light receiving unit 13a corresponding to the region ROI _A (see FIG. 2) including the identification object S, and the region ROI _B (FIG. 2) not including the identification object S. ), which is the output data of the light receiving unit 13a corresponding to the second data.

Both the first data and the second data may be partial data of the reflected image data of the entire banknote BN, that is, partial reflected image data of the banknote BN. The regions ROI _A and ROI _B may be set in advance according to the denomination of the banknote BN, and the control unit 20a controls the position information of the regions ROI _A and ROI _B set for each denomination, The first data and the second data may be extracted from the output data of the light receiving unit 13a (for example, the reflection image data of the entire bill BN).

Then, the control unit 20a performs a process of generating third data by correcting the first data using the second data (hereinafter sometimes referred to as correction process), and a process of identifying banknotes BN based on the third data ( hereinafter, may be referred to as identification processing). Characteristic variations of the light emitting elements 17a (e.g., LEDs) of the light source 11a, shifts in peak wavelength due to temperature, and variations in transmittance of the light guide 15a (e.g., acrylic resin light guide) of the light source 11a according to the wavelength. , the output data of the light receiving unit 13a may vary due to environmental factors such as variations in characteristics of the light receiving element itself of the light receiving unit _13a . Third data is generated by correcting the first data, which is the output data of the corresponding light-receiving unit 13a, with the second data, which is the output data of the light-receiving unit 13a corresponding to the region ROI _B not including the identification object S. Therefore, it is possible to reduce variations in the output data (especially the first data) caused by the environmental factors. Since the bill BN is identified based on the corrected third data, the bill BN can be identified based on the data with reduced variation. Therefore, it is possible to improve the identification accuracy of the bill BN.

In the correction process, the control section 20a may generate the third data by normalizing the first data with the second data. For example, a process of dividing each output value (pixel value) of the first data by the output value of the second data may be performed.

Further, the control unit 20a may use, as the second data, a representative value (for example, average value, median value, etc.) of the output data of the light receiving unit 13a corresponding to the region ROI _B not including the identification object S. For example, each output value (pixel value) of the first data is normalized (divided) using the average value of the output values (pixel values) included in the reflection image data of the region ROI _B that does not include the identification object S. You may

The light source 11a may irradiate the banknote BN with light of multiple wavelengths, and the light receiving unit 13a may receive light of multiple wavelengths coming from the banknote BN. In the correction process, the control unit 20a corrects the first data related to the light of multiple wavelengths with the corresponding second data related to the light of the same wavelength. The third data relating to light may be generated, and in the identification process, the bill BN may be identified based on the third data relating to light of multiple wavelengths. As a result, it is possible to highly accurately identify the bill BN provided with the identification object S (for example, special ink) whose characteristic (for example, reflectance) changes according to the wavelength.

Further, in this case, the control unit 20a controls the first multiplication data obtained by multiplying the data relating to the light of the first wavelength and the data relating to the light of the second wavelength out of the first data relating to the light of the plurality of wavelengths, A process of calculating second multiplication data, which is data obtained by multiplying the first wavelength data and the second wavelength light data among the second data relating to the wavelength light (hereinafter, may be referred to as multiplication process ) may be performed, and in the correction process, a process of further generating fourth data obtained by correcting the first multiplied data with the second multiplied data may be performed, and in the identification process, third data relating to light of a plurality of wavelengths may be performed. and the fourth data. As a result, it is possible to improve the performance of separating the authenticity of the identification object S (especially the special ink). Therefore, it is possible to further improve the accuracy of bill BN identification.

With general inks, such as infrared absorbing inks and infrared non-absorbing inks, there is almost no difference in reflectance in the infrared region. The vector (1, 1, 1) passing through is distributed in the ^T direction. Specialty inks, on the other hand, are not. Therefore, the product of output data related to light of multiple wavelengths is more susceptible to general inks than special inks, which contributes to an improvement in the degree of separation between special inks and general inks.

It should be noted that "light of multiple wavelengths" means light having different wavelength bands, and includes at least light of a first wavelength and light of a second wavelength. For example, light of two wavelengths, that is, light of a first wavelength and light of a second wavelength, or light of three wavelengths, that is, light of a first wavelength, light of a second wavelength, and light of a third wavelength may be used. may be light with a wavelength of The light of multiple wavelengths may be, for example, visible light that has different colors, and infrared light and ultraviolet light that have wavelength bands that partially overlap each other or light that does not overlap with each other. may be

Further, "the first data (second data) relating to light of multiple wavelengths" is the first data (second data) based on the data output when the light receiving section 13a receives the light of each wavelength. It includes the first data (second data) related to the light of the first wavelength to the first data (second data) related to the light of the Nth wavelength (N is an integer equal to or greater than 2).

When light of two wavelengths is used, the control unit 20a converts the first data (hereinafter referred to as the first data of λ1) related to the light of the first wavelength to the second data related to the light of the first wavelength in the correction process. (hereinafter referred to as the second data of λ1) may be generated for the light of the first wavelength (hereinafter referred to as the third data of λ1), and the first data of the light of the second wavelength (hereinafter, the first data of λ2) is corrected with the second data of the light of the second wavelength (hereinafter, the second data of λ2), and the third data (hereinafter, the third data of λ2) related to the light of the second wavelength. third data) may be generated. When using light of three wavelengths, in the correction process, the control unit 20a further converts first data related to light of the third wavelength (hereinafter, first data of λ3) to third data related to light of the third wavelength. Third data (hereinafter, third data of λ3) related to light of a third wavelength corrected by two data (hereinafter, second data of λ1) may be generated.

When using light of two wavelengths, the control unit 20a multiplies the first data of λ1 by the first data of λ2 (hereinafter referred to as the first data of λ1×λ2) as the first multiplication data in the multiplication process. ) may be calculated, and data obtained by multiplying the second data of λ1 by the second data of λ2 (hereinafter referred to as the second data of λ1×λ2) may be calculated as the second multiplication data. As the fourth data, data obtained by correcting the first data of λ1×λ2 with the second data of λ1×λ2 (hereinafter referred to as fourth data of λ1×λ2) may be generated.

When light of three wavelengths is used, the control unit 20a further multiplies the first data of λ1 by the first data of λ3 (hereinafter referred to as the first data of λ1×λ3) as the first multiplication data in the multiplication process. ) and data obtained by multiplying the first data of λ2 by the first data of λ3 (hereinafter referred to as the first data of λ2×λ3). data obtained by multiplying the data by the second data of λ3 (hereinafter referred to as second data of λ1×λ3) and data obtained by multiplying the second data of λ2 by the second data of λ3 (hereinafter referred to as second data of λ2×λ3) In the correction process, as fourth data, data obtained by correcting the first data of λ1×λ3 with the second data of λ1×λ3 (hereinafter referred to as fourth data of λ1×λ3) and data obtained by correcting the first data of λ2×λ3 with the second data of λ2×λ3 (hereinafter referred to as fourth data of λ2×λ3).

When light of two wavelengths is used, the first multiplication data is obtained by multiplying each output value (pixel value) of the first data for the light of the first wavelength with each output value of the second data for the light of the second wavelength. (Pixel value) multiplied data (however, data obtained by multiplying output values relating to the same point in the XY plain). Similarly, when using light of three wavelengths, output values (pixel values) may be multiplied together (however, output values relating to the same point in the XY plane) may be multiplied.

When using light of two wavelengths, the second multiplication data is data obtained by multiplying the representative value of the second data relating to the light of the first wavelength by the representative value of the second data relating to the light of the second wavelength (however, , representative values of the same type (for example, average values)). When using light of three wavelengths, representative values (however, representative values of the same type) may be similarly multiplied.

When light of two wavelengths is used, the control unit 20a may identify banknotes BN based on the third data of λ1 and the third data of λ2 (two-dimensional feature amount) in the identification process, The bill BN may be identified based on the third data of λ1, the third data of λ2, and the fourth data of λ1×λ2 (three-dimensional feature amount).

When light of three wavelengths is used, the control unit 20a identifies the banknote BN based on the third data of λ1, the third data of λ2, and the third data of λ3 (three-dimensional feature amount) in the identification process. Alternatively, the third data of λ1, the third data of λ2, the third data of λ3, the fourth data of λ1×λ2, the fourth data of λ1×λ3, and the fourth data of λ2×λ3 (6 The banknote BN may be identified based on the dimensional feature amount).

When light of multiple wavelengths is used as described above, the light receiving unit 13a may receive light of multiple wavelengths reflected by the banknote BN while the light of multiple wavelengths is emitted from the light source 11a. . At this time, the light receiving section 13a can function as a sensor sensitive to at least the wavelength band of the light emitted from the light source 11a. The light receiving section 13a may output an electrical signal corresponding to the amount of received light as output data for each wavelength. More specifically, the light-receiving section 13a may include a light-receiving element, the light-receiving element may receive light and convert it into an electrical signal corresponding to the amount of incident light, and the light-receiving section 13a may convert the electrical signal into You may output for every wavelength.

When using light of multiple wavelengths, the light of each wavelength emitted by the light source 11a may be light of a wavelength band including the peak wavelength and its neighboring wavelengths. , may have different peak wavelengths. Also, the light source 11a may include a plurality of light emitting elements 17a having different peak wavelengths. For example, the light source 11a may irradiate infrared light with a plurality of wavelengths with different peak wavelengths, or may include a plurality of light emitting elements 17a that respectively irradiate infrared light with a plurality of wavelengths with different peak wavelengths. . Further, the light receiving unit 13a may receive infrared light of a plurality of wavelengths irradiated from the light source 11a and reflected by the bill BN. Similarly, the first data and the second data may each be data relating to infrared light of multiple wavelengths. Further, the various data related to light of multiple wavelengths processed by the control unit 20a may be data related to infrared light of multiple wavelengths.

For example, the light source 11a may irradiate a plurality of wavelengths of infrared light (first and second infrared light, or first to third infrared light) having different peak wavelengths, and the light receiving section 13a , infrared light of a plurality of wavelengths (first and second infrared light, or first to third infrared light) emitted from the light source 11a and reflected by the banknote BN may be received, and the first data and second data may each include data relating to infrared light of multiple wavelengths (first and second infrared light, or first to third infrared light). Various data related to light of multiple wavelengths processed by the control unit 20a are data related to infrared light of multiple wavelengths (for example, first and second infrared lights, or first to third infrared lights). may be

The first and second infrared light are infrared light with a peak wavelength in the wavelength band of 770 to 830 nm, infrared light with a peak wavelength in the wavelength band of 840 to 900 nm, and a wavelength band of 910 to 970 nm. It may be a combination of any two of infrared light having a peak wavelength. Either of the wavelengths of the first and second infrared light may be longer.

Similarly, the first to third infrared light includes infrared light having a peak wavelength in the wavelength band of 770 to 830 nm, infrared light having a peak wavelength in the wavelength band of 840 to 900 nm, and infrared light having a peak wavelength in the wavelength band of 910 to 970 nm. It may be a combination with infrared light having a peak wavelength in the wavelength band. The magnitude relationship of the wavelengths of the first to third infrared light is not particularly limited.

As shown in FIG. 4, the light source 11a may irradiate the banknote BN with linear light in the main scanning direction (Y direction), and the light receiving unit 13a receives the light from the banknote BN in the main scanning direction (Y direction). The control unit 20a may receive linear light in the main scanning direction (Y direction), and the control unit 20a, as the second data, stores the position of the region ROI _A (see FIG. 2) including the identification object S in the main scanning direction (Y direction). You may use the output data according to. When the position in the main scanning direction changes, the length of the light guide 15a (for example, a light guide made of acrylic resin) of the light source 11a through which light passes also changes, so the output data also changes in the main scanning direction. The variation becomes more pronounced at the center of the direction (the center of the light guide _15a ). Since the output data according to the position is used, it is possible to reduce variations in the output data due to the position in the main scanning direction. Further, although characteristic variations of the light receiving elements may occur depending on the position in the main scanning direction, the above configuration can reduce such characteristic variations of the light receiving elements. Therefore, it is possible to further improve the accuracy of bill BN identification.

In this case, the region ROI _A including the identification target S and the region ROI _B not including the identification target S are set at the same location (same range) on the banknote BN in the main scanning direction (Y direction). Alternatively, both the first data and the second data may be data of the same channel range included in the reflection image data of the entire banknote BN. For example, the first data and the second data may be data of channels n to m (where n and m are natural numbers that satisfy n<m) of the reflection image data of the entire banknote BN.

The range in the sub-scanning direction (X direction) of the first data and the second data, that is, the number of lines, can be set as appropriate, and may be the same or different.

In the identification process, the control unit 20a may apply the identification function to each pixel and determine for each pixel whether or not the pixel has special ink. That is, the above-described various data used in the identification process are input to the identification function as feature amounts (for example, two-dimensional, three-dimensional, or six-dimensional feature amounts), and based on the output of the identification function, the banknote BN is identified as the identification object S may be determined whether is provided. As a result, it is possible to speed up the identification processing by the control unit 20a.

Here, the discriminant function can be generated by supervised machine learning. Specifically, for example, discriminant analysis, support vector machine, neural network, etc. can be used. As the teacher data, for example, image data including the ink portion of a banknote printed with special ink and its background portion (peripheral portion) can be used. Here, the special ink portion and the background portion, ie, the non-special ink portion, can be class labels. For example, in the case of negative ink, image data related to infrared light with a peak wavelength in the wavelength band of 910 to 970 nm is binarized (separated into the ink portion and the background portion), and the result is used as a class label for each pixel. can be For positive ink, image data related to infrared light with a peak wavelength in the wavelength band of 770 to 830 nm is binarized (separated into the ink portion and the background portion), and the result is used as the class label for each pixel as it is. be able to. In either case, Otsu's binarization may be performed as the binarization processing.

More specifically, for example, when light of three wavelengths is used, the control unit 20a determines whether the bill BN is provided with the identification object S based on the following equations (1) to (6) in the identification process. It may be determined whether Here, equation (3') may be used instead of equation (3).

In equations (1) and (2), L is a threshold value, and in equation (1), if λ is greater than or equal to L, it is determined that the identification object S is provided on the bill BN, and λ is less than L. If so, it is determined that the identification object S is not provided on the bill BN.

In Equation (2), λ is an evaluation value, and the total sum of P _j within the region ROI _A including the identification object S is calculated.

In each equation, Pj is the result of the discriminant function f( _x ), the sum of pixels determined to have the special ink (equation (3)), or the classification score, which is the output of the discriminant function f(x). can be used (equation (3′)). In equations (3) and (3′), c is the classification score threshold.

The discriminant function f(x) is represented by Equation (4), and a three-dimensional feature quantity is input as shown in Equation (6). In Equation (5), ω(w ₀ to w ₃ ) is the coefficient vector (weight) obtained as a result of machine learning, and φ(x _j ) represented by Equation (6) is the target pixel j(j is the feature amount vector of the number indicating the target pixel). In equation (6), x _1j , x _2j and x _3j respectively relate to the first, second and third lights (which may be the first, second and third infrared lights) at the target pixel _j . are pixel values, and μ ₁ , μ ₂ and _{μ 3} are the first, second and third lights (first, second and third infrared It is a representative value of output data related to light. Here, the discriminant function f(x) is represented by a linear discriminant formula.

In equation (6), x _1j /μ ₁ , x _2j /μ ₂ and x _3j /μ ₃ are the third data of λ1, the third data of λ2, and the third data of λ3, respectively. handle.

Further, when using light of three wavelengths, the control unit 20a determines whether or not the identification object S is provided on the banknote BN based on the following equations (11) to (16) in the identification process. good too. Here, equation (13') may be used instead of equation (13).

In equations (11) and (12), L is a threshold value. If so, it is determined that the identification object S is not provided on the bill BN.

In Equation (12), λ is an evaluation value, and the sum of P _j in the region ROI _A including the identification object S is calculated.

In each equation, Pj is the result of the discriminant function f( _x ), the sum of pixels determined to have the special ink (equation (13)), or the classification score, which is the output of the discriminant function f(x). can be used (equation (13')). In equations (13) and (13′), c is the classification score threshold.

The discriminant function f(x) is represented by Equation (14), and six-dimensional feature quantities are input as shown in Equation (16). In Equation (15), ω(w ₀ to w ₆ ) is the coefficient vector (weight) obtained as a result of machine learning, and φ(x _j ) represented by Equation (16) is the target pixel j(j is the feature amount vector of the number indicating the target pixel). In equation (16), x _1j , x _2j and x _3j respectively relate to the first, second and third lights (which may be the first, second and third infrared lights) at the target pixel _j . are pixel values, and μ ₁ , μ ₂ and _{μ 3} are the first, second and third lights (first, second and third infrared It is a representative value of output data related to light. Here, the discriminant function f(x) is represented by a formula obtained by extending the linear discriminant formula to a nonlinear model.

In addition, in formula (16), x _1j /μ ₁ , x _2j /μ ₂ , x _3j /μ ₃ , x _1j x _2j /μ ₁ μ ₂ , x _1j x _3j /μ ₁ μ ₃ and x _2j x _3j /μ ₂ μ ₃ are the above-described third data of λ1, third data of λ2, third data of λ3, fourth data of λ1×λ2, fourth data of λ1×λ3, and λ2×λ3, respectively. It corresponds to the fourth data.

The control unit 20a may perform the multiplication process at the same time as the correction process in the same calculation process, for example, as described with the above equations (6) and (16).

The control unit 20a may identify the authenticity of the bill BN in the identification process. For example, if it is determined that the banknote BN is provided with the identification target S, the banknote BN may be determined to be genuine, and if it is determined that the banknote BN is not provided with the identification target S, the banknote BN may be determined to be genuine. The banknote BN may be determined as a counterfeit note.

Next, the operation of the paper sheet identification device 1a according to this embodiment will be described with reference to FIG. FIG. 7 is a flowchart for explaining an example of the operation of the paper sheet identification device according to this embodiment.

As shown in FIG. 7, first, the control unit 20a acquires output data from the light receiving unit 13a that receives the light emitted from the light source 11a and coming (for example, reflected) from the bill BN (step S11).

Next, the control unit 20a controls the first data, which is the output data of the light receiving unit 13a corresponding to the region ROI _A including the identification target S, and the light receiving unit corresponding to the region ROI _B not including the identification target S. The second data, which is the output data of 13a, is acquired (step S12).

Next, the control unit 20a performs a correction process of generating third data by correcting the first data using the second data (step S13). In step S13, the control unit 20a may perform multiplication processing along with correction processing.

After that, the control unit 20a performs identification processing for identifying the bill BN based on the third data (step S14), and the operation of the paper sheet identification device 1a is completed.

(Embodiment 2)
The configuration of the paper sheet identifying apparatus according to this embodiment will be described with reference to FIG. FIG. 8 is a schematic diagram for explaining an example of the configuration of the paper sheet identification device according to the present embodiment, and is a diagram of the banknote transport path as seen from the side. As shown in FIG. 8, the paper sheet identification device 1b according to the present embodiment includes a light source 11b that irradiates light of multiple wavelengths onto the banknote BN, and a light receiving unit 13b that receives light of multiple wavelengths coming from the banknote BN. , and a control unit 20b that acquires output data related to light of multiple wavelengths from the light receiving unit 13b. The bill BN to be identified may be conveyed in the X direction within the XY plane.

FIG. 9 is a schematic plan view showing an example of banknotes to be identified in this embodiment. As shown in FIG. 9, an identification object S is provided (for example, printed) on at least one main surface of the banknote BN to be identified in this embodiment. For example, a rectangular area ROI _A including the identification object S is set on the main surface of the banknote BN.

As shown in FIG. 3, the banknote BN to be identified has an ink (negative ink) whose reflectance decreases as the wavelength increases in the infrared region and an ink (negative ink) in which the wavelength increases in the infrared region. It may contain at least one of ink (positive ink) whose reflectance increases as it increases. According to the paper sheet identification device 1b, it is possible to identify such banknotes BN containing ink with high accuracy.

The light source 11b irradiates the bill BN with light of multiple wavelengths. The type (wavelength) of light emitted from the light source 11b is not particularly limited, and includes visible light such as white light, red light, green light, and blue light, infrared light, and the like.

It should be noted that "light of multiple wavelengths" means light having different wavelength bands, and includes at least light of a first wavelength and light of a second wavelength. For example, light of two wavelengths, that is, light of a first wavelength and light of a second wavelength, or light of three wavelengths, that is, light of a first wavelength, light of a second wavelength, and light of a third wavelength may be used. may be light with a wavelength of The light of multiple wavelengths may be, for example, visible light that has different colors, and infrared light and ultraviolet light that have wavelength bands that partially overlap each other or light that does not overlap with each other. may be

The light receiving unit 13b receives light of multiple wavelengths coming from the bill BN. That is, it can function as an optical sensor. The light receiving unit 13b may receive light of multiple wavelengths emitted from the light source 11b and reflected by the bill BN. That is, while the light source 11b irradiates light of multiple wavelengths, the light receiving unit 13b may receive light of multiple wavelengths reflected by the bill BN. At this time, the light receiving section 13b can function as a sensor sensitive to at least the wavelength band of the light emitted from the light source 11b. The light receiving section 13b may output an electrical signal corresponding to the amount of received light as output data for each wavelength. More specifically, the light-receiving section 13b may include a light-receiving element, the light-receiving element may receive light and convert it into an electrical signal corresponding to the amount of incident light, and the light-receiving section 13b may convert the electrical signal to You may output for every wavelength.

FIG. 10 is a schematic diagram illustrating an example of the configuration of the paper sheet identification device according to the present embodiment, and is a diagram viewed from an oblique direction. As shown in FIG. 10, the light source 11b and the light receiving section 13b may constitute an optical line sensor 14b extending in the Y direction. In this case, the Y direction corresponds to the main scanning direction of the optical line sensor 14b, and the X direction corresponds to the sub scanning direction of the optical line sensor 14b. The light source 11b may emit light in a straight line extending in the Y direction. The light-receiving section 13b may include a plurality of light-receiving elements (light-receiving pixels) arranged in a line in the Y direction, and may constitute a linear image sensor.

Also, the lengths of the light source 11b and the light receiving section 13b in the Y direction (main scanning direction) may be longer than the length of the bill BN in the Y direction. Then, the light source 11b may linearly irradiate the entire banknote BN in the Y direction, and the light receiving unit 13b may receive the light reflected in the entire Y direction of the banknote BN. That is, the light receiving section 13b may output electrical signals corresponding to the amount of incident light on a plurality of channels corresponding to a plurality of light receiving elements (positions in the Y direction). A channel is a number assigned to the light receiving elements in order in the Y direction. At this time, the light receiving section 13b outputs, as output data, line data, which is data relating to light received simultaneously in each channel. By repeating the light irradiation by the light source 11b and the light reception by the light receiving unit 13b while conveying the banknote BN in the X direction (sub-scanning direction), it is possible to acquire data related to the reflected light of the entire banknote BN. good.

FIG. 11 is a schematic diagram for explaining an example of the configuration of the paper sheet recognition apparatus according to the present embodiment, and is a view of the banknote transport path from above. As shown in FIG. 11, the light source 11b may include a light guide 15b and light emitting elements 17b facing two end surfaces 15ba of the light guide 15b. BN may be irradiated with light.

The light guide 15b is a transparent, rod-shaped optical member that guides the light from the light emitting element 17b and irradiates the banknote BN, which is an irradiation target, with linear light. Linearize the light.

The light guide 15b may be made of acrylic resin.

The light emitting element 17b is an element that emits light toward the opposing end face 15ba, and for example, an LED can be used. A plurality of light emitting elements 17b may be provided for the corresponding end surfaces. Moreover, the light emitting element 17b may be arranged so as to face only one of the two end surfaces 15ba.

The light source 11b may irradiate the bill BN with infrared light including light with a wavelength of 850 nm or more and 950 nm or less. As a result, it is possible to highly accurately identify banknotes BN that include, as identification objects S, ink whose reflectance varies in the infrared region around 900 nm (for example, special ink).

Each light-receiving pixel of the light-receiving section 13b may include a light-receiving element having sensitivity over a plurality of different wavelength bands, or may include a plurality of types of light-receiving elements that selectively receive light in different wavelength bands. may be In the former case, the light source 11b may sequentially irradiate the banknote BN with light of a plurality of wavelengths, and the light receiving section 13b may receive the light of each wavelength in accordance with the irradiation timing of the light of each wavelength. In the latter case, the light source 11b may simultaneously irradiate the banknote BN with light of multiple wavelengths, and the light receiving section 13b may receive light of multiple wavelengths with multiple types of light receiving elements.

The control unit 20b performs a process of acquiring output data related to light of multiple wavelengths from the light receiving unit 13b. That is, data for each wavelength corresponding to the amount of light received by the light receiving section 13b is obtained. Note that "output data relating to light of multiple wavelengths" is data output when the light receiving unit 13b receives light of each wavelength, and the output data relating to light of the first wavelength to the Nth ( (N is an integer equal to or greater than 2). The output data of the light receiving unit 13b acquired by the control unit 20b may be digitized. The control unit 20b may acquire image data of the entire bill BN as the output data of the light receiving unit 13b.

The image data of the entire banknote BN is data (two-dimensional data) obtained by imaging the entire banknote BN, and as shown in FIG. It may be composed of a plurality of arranged pixels Pix. The address of each pixel Pix may be specified by the channel of the light receiving section 13b corresponding to the position in the Y direction and the line corresponding to the position in the X direction. A line is a number assigned in order to line data sequentially output from the light receiving unit 13b.

The output data of the light receiving unit 13b acquired by the control unit 20b may include data related to light reflected by the bill BN. As a result, it is possible to highly accurately identify banknotes BN that include ink (for example, special ink) with characteristic reflectance as the identification object S.

Further, the control unit 20b may acquire the image data related to the reflected light of the entire banknote BN, that is, the reflected image data of the entire banknote BN, as the output data of the light receiving unit 13b.

The resolution of the output data acquired by the control unit 20b may be the same as or different from the resolution of the output data of the light receiving unit 13b. sub-scanning direction).

The control unit 20b may control each part of the paper sheet recognition apparatus 1b. and various hardware (for example, FPGA) controlled by the CPU.

The control unit 20b performs a process of calculating multiplication data, which is data obtained by multiplying the data (output data) related to the light of the first wavelength and the second wavelength out of the acquired output data related to light of multiple wavelengths. (hereinafter sometimes referred to as multiplication processing) is performed, and processing for identifying banknotes BN (hereinafter sometimes referred to as identification processing) is performed based on the output data related to light of multiple wavelengths and the multiplication data. As a result, it is possible to improve the performance of separating the authenticity of the identification object S (especially the special ink). Therefore, it is possible to improve the identification accuracy of the bill BN.

With general inks, such as infrared absorbing inks and infrared non-absorbing inks, there is almost no difference in reflectance in the infrared region. The vector (1, 1, 1) passing through is distributed in the ^T direction. Specialty inks, on the other hand, are not. Therefore, the product of output data related to light of multiple wavelengths is more susceptible to general inks than special inks, which contributes to an improvement in the degree of separation between special inks and general inks.

The output data related to light of multiple wavelengths acquired by the control unit 20b from the light receiving unit 13b may be data corresponding to the region ROI _A including the identification object S. FIG. In other words, the output data relating to light of multiple wavelengths may be partial data of the reflected image data of the entire banknote BN, that is, partial reflected image data of the banknote BN. The area ROI _A may be set in advance according to the denomination of the banknote BN, and the control unit 20b controls the output data of the light receiving unit 13b based on the position information of the area ROI _A set for each denomination. Data corresponding to the region ROI _A including the identification object S may be extracted from (for example, reflection image data of the entire bill BN).

When light of two wavelengths is used, the control unit 20b converts the output data related to the light of the first wavelength (hereinafter referred to as the output data of λ1) to the output data related to the light of the second wavelength as the multiplication data in the multiplication process. (hereinafter, output data of λ2) may be calculated by multiplying data (hereinafter, output data of λ1×λ2). The paper money BN may be identified based on the output data of xλ2 (three-dimensional feature amount).

When light of three wavelengths is used, the control unit 20b further multiplies the output data of λ1 by the output data of light of the third wavelength (hereinafter referred to as the output data of λ3) as multiplication data in the multiplication process. (hereinafter, output data of λ1×λ3) and data obtained by multiplying the output data of λ2 by the output data of λ3 (hereinafter, output data of λ2×λ3). In the processing, based on the output data of λ1, the output data of λ2, the output data of λ3, the output data of λ1×λ2, the output data of λ1×λ3, and the output data of λ2×λ3 (six-dimensional feature amount), A banknote BN may be identified.

When light of two wavelengths is used, the multiplication data is obtained by multiplying each output value (pixel value) of the output data of the light of the first wavelength with each output value (pixel value) of the output data of the light of the second wavelength. (However, the data obtained by multiplying the output values related to the same point in the XY plain) may be used. Similarly, when using light of three wavelengths, output values (pixel values) may be multiplied together (however, output values relating to the same point in the XY plane) may be multiplied.

In the present embodiment, the light of each wavelength emitted by the light source 11b may be light of a wavelength band including the peak wavelength and a wavelength in the vicinity thereof, and the light of a plurality of wavelengths emitted by the light source 11b may have peak wavelengths. can be different. Moreover, the light source 11b may include a plurality of light emitting elements 17b having different peak wavelengths. For example, the light source 11b may irradiate infrared light with a plurality of wavelengths with different peak wavelengths, or may include a plurality of light emitting elements 17b that respectively irradiate infrared light with a plurality of wavelengths with different peak wavelengths. . Further, the light receiving unit 13b may receive infrared light of a plurality of wavelengths irradiated from the light source 11b and reflected by the bill BN. Similarly, the output data related to light of multiple wavelengths acquired by the control unit 20b from the light receiving unit 13b may be data related to infrared light of multiple wavelengths. Further, the various data related to light of multiple wavelengths processed by the control unit 20b may be data related to infrared light of multiple wavelengths.

For example, the light source 11b may irradiate a plurality of wavelengths of infrared light (first and second infrared light, or first to third infrared light) with different peak wavelengths, and the light receiving unit 13b , may receive infrared light of a plurality of wavelengths (first and second infrared light, or first to third infrared light) emitted from the light source 11b and reflected by the banknote BN, and the control unit 20b may acquire data related to infrared light of multiple wavelengths (first and second infrared light, or first to third infrared light) from the light receiving section 13b. Various data related to multi-wavelength light processed by the control unit 20b are data related to multi-wavelength infrared light (eg, first and second infrared light, or first to third infrared light). may be

The first and second infrared light are infrared light with a peak wavelength in the wavelength band of 770 to 830 nm, infrared light with a peak wavelength in the wavelength band of 840 to 900 nm, and a wavelength band of 910 to 970 nm. It may be a combination of any two of infrared light having a peak wavelength. Either of the wavelengths of the first and second infrared light may be longer.

Similarly, the first to third infrared light includes infrared light having a peak wavelength in the wavelength band of 770 to 830 nm, infrared light having a peak wavelength in the wavelength band of 840 to 900 nm, and infrared light having a peak wavelength in the wavelength band of 910 to 970 nm. It may be a combination with infrared light having a peak wavelength in the wavelength band. The magnitude relationship of the wavelengths of the first to third infrared light is not particularly limited.

In the identification process, the control unit 20b may apply the identification function to each pixel and determine for each pixel whether or not the pixel has special ink. That is, the above-described various data used in the identification process are input to the identification function as a feature amount (for example, a three-dimensional or six-dimensional feature amount), and based on the output of the identification function, the banknote BN is provided with the identification target S. It may be determined whether or not As a result, it is possible to speed up the identification processing by the control unit 20b.

Here, the discriminant function can be generated by supervised machine learning. Specifically, for example, discriminant analysis, support vector machine, neural network, etc. can be used. As the teacher data, for example, image data including the ink portion of a banknote printed with special ink and its background portion (peripheral portion) can be used. Here, the feature amount (for example, three-dimensional or six-dimensional feature amount) related to the various data described above can be input, and the special ink portion and the background portion, that is, the non-special ink portion can be used as class labels. For example, in the case of negative ink, image data related to infrared light with a peak wavelength in the wavelength band of 910 to 970 nm is binarized (separated into the ink portion and the background portion), and the result is used as a class label for each pixel. can be For positive ink, image data related to infrared light with a peak wavelength in the wavelength band of 770 to 830 nm is binarized (separated into the ink portion and the background portion), and the result is used as the class label for each pixel as it is. be able to. In either case, Otsu's binarization may be performed as the binarization processing.

More specifically, for example, when light of three wavelengths is used, the control unit 20b, in the identification process, determines whether the identification object S is provided on the banknote BN based on the following equations (21) to (26). It may be determined whether Here, equation (23') may be used instead of equation (23).

In equations (21) and (22), L is a threshold value. If so, it is determined that the identification object S is not provided on the bill BN.

In Equation (22), λ is an evaluation value, and the sum of P _j within the region ROI _A including the identification object S is calculated.

In each equation, Pj is the result of the discriminant function f( _x ), the sum of pixels determined to have the special ink (equation (23)), or the classification score, which is the output of the discriminant function f(x). can be used (equation (23')). In equations (23) and (23′), c is the classification score threshold.

The discriminant function f(x) is represented by Equation (24), and six-dimensional feature quantities are input as shown in Equation (26). In Equation (25), ω(w ₀ to w ₆ ) is a coefficient vector obtained as a result of machine learning, and φ(x _j ) represented by Equation (26) is the target pixel j (j is the target number indicating a pixel). In equation (26), x _1j , x _2j and x _3j respectively relate to the first, second and third lights (which may be the first, second and third infrared lights) at the target pixel _j . pixel value. Here, the discriminant function f(x) is represented by a formula obtained by extending the linear discriminant formula to a nonlinear model.

In equation (26), x _1j , x _2j , x _3j , x _1j x _2j , x _1j x _3j and x _2j x _3j are the output data of λ1, the output data of λ2, and the output of λ3, respectively. data, λ1×λ2 output data, λ1×λ3 output data, and λ2×λ3 output data.

The control unit 20b may identify the authenticity of the bill BN in the identification process. For example, if it is determined that the banknote BN is provided with the identification target S, the banknote BN may be determined to be genuine, and if it is determined that the banknote BN is not provided with the identification target S, the banknote BN may be determined to be genuine. The banknote BN may be determined as a counterfeit note.

Next, the operation of the paper sheet identifying apparatus 1b according to this embodiment will be described with reference to FIG. FIG. 12 is a flowchart for explaining an example of the operation of the paper sheet identification device according to this embodiment.

As shown in FIG. 12, first, the control unit 20b acquires output data from the light receiving unit 13b that receives light of multiple wavelengths that is emitted from the light source 11b and comes (for example, is reflected) from the bill BN (step S21). .

Next, the control unit 20b performs multiplication for calculating multiplication data, which is data obtained by multiplying the data related to the light of the first wavelength and the data related to the light of the second wavelength out of the acquired output data related to the light of the plurality of wavelengths. (Step S22).

If the data relating to the light of the first wavelength and the second wavelength are the data corresponding to the region ROI _A including the identification object S, before step S22, the output data relating to the light of each wavelength are Data corresponding to the region ROI _A containing the identification object S (for example, reflection image data of the region ROI _A containing the identification object S) is extracted from data corresponding to the entire BN (for example, reflection image data of the entire bill BN). processing may be performed.

After that, the control unit 20b determines the banknote BN based on the output data (data corresponding to the region ROI _A including the identification target S) obtained from the light receiving unit 13b and the calculated multiplication data. is performed (step S23), and the operation of the sheet identification apparatus 1b is completed.

(Embodiment 3)
With reference to FIG. 13, the configuration of a paper sheet processing apparatus in which the paper sheet identifying apparatus according to the present embodiment can be mounted will be described. FIG. 13 is a schematic perspective view showing the appearance of an example of a paper sheet processing apparatus in which the paper sheet identifying apparatus according to the present embodiment can be mounted. A paper sheet processing apparatus equipped with the paper sheet identification apparatus according to the present embodiment may have, for example, the configuration shown in FIG. 13 . A paper sheet processing apparatus 300 shown in FIG. 13 includes a bill identification apparatus (not shown in FIG. 13) according to the present embodiment that performs identification processing of bills, and a plurality of bills to be processed are placed in a stacked state. A hopper 301, two reject units 302 from which rejected banknotes are discharged, an operation unit 303 for inputting instructions from an operator, and a banknote whose denomination, authenticity and fitness are identified in a housing 310. It is provided with four stacking units 306a to 306d for sorting and stacking, and a display unit 305 for displaying information such as identification count results of banknotes and the stacking status of each stacking unit 306a to 306d.

Next, with reference to FIG. 14, the configuration of the paper sheet identification device according to this embodiment will be described. FIG. 14 is a block diagram illustrating an example of the configuration of the paper sheet identification device according to this embodiment. As shown in FIG. 14 , the paper sheet identification device 100 according to this embodiment includes an optical line sensor 110 , a control section 120 , a storage section 130 and a transport section 140 .

The optical line sensor 110 detects various optical characteristics of the transported banknotes, and may include a light source 111 and a light receiving unit 113 along the transport path of the banknotes. The light source 111 irradiates the banknote with light of multiple wavelengths, the light receiving unit 113 receives the light of multiple wavelengths emitted from the light source 111 and reflected by the banknote, and outputs data related to the light of multiple wavelengths for each wavelength. do.

The control unit 120 includes a program (including a sheet identification program) for realizing various types of processing stored in the storage unit 130, a CPU that executes the program, and various types of hardware controlled by the CPU ( For example, it is configured by an FPGA) or the like. The control unit 120 controls each unit of the paper sheet identification device 100 according to the program stored in the storage unit 130 . In addition, the control unit 120 performs acquisition processing of output data from the light receiving unit 113, correction processing of the acquired output data, multiplication processing of the acquired output data, correction and/or multiplication by the program stored in the storage unit 130. It has a function to perform processing such as identification processing using various data. These processes by the control unit 120 are the same as the processes by the control unit 10a or 10b described in the first or second embodiment, so detailed description thereof will be omitted.

As identification processing, the control unit 120 performs processing for identifying at least the denomination and authenticity of the bill. According to the identification processing using the corrected and/or multiplied various data described in the first or second embodiment, the authenticity of the banknote can be identified. The control unit 120 may have a function of determining fitness of banknotes. In this case, the control unit 120 has a function of determining whether the banknote should be processed as a fit banknote that can be reused in the market or as an unfit banknote that is not suitable for market circulation, by detecting stains, folds, tears, and the like on the banknote. have

The storage unit 130 is composed of a non-volatile and/or volatile storage device such as a semiconductor memory or a hard disk, and stores various programs and data for controlling the sheet identification device 100 .

The conveying unit 140 rotates a plurality of rollers, belts, and the like, and conveys banknotes one by one along a conveying path provided in the paper sheet recognition apparatus 100 .

Next, the configuration of the optical line sensor 110 will be described using FIG. FIG. 15 is a schematic cross-sectional view illustrating an example of the configuration of an optical line sensor included in the paper sheet identification device according to this embodiment. As shown in FIG. 15, the optical line sensor 110 is composed of a contact image sensor facing the conveying path 311 of the paper sheet processing apparatus, and constitutes a part of the conveying path 311 . Banknotes BN are conveyed in the X direction within the conveyance path 311 (XY plane). The Y direction corresponds to the main scanning direction of the optical line sensor 110 , and the X direction corresponds to the sub scanning direction of the optical line sensor 110 .

As shown in FIG. 15, the optical line sensor 110 includes two light sources 111 for reflection, a condenser lens 112, a light receiving section 113, and a substrate 114. As shown in FIG. The light source 111 for reflection includes, for example, a light guide extending in the main scanning direction, and a plurality of types of light emitting elements facing at least one end surface of the light guide and emitting light of a plurality of wavelengths, Light of a plurality of wavelengths is sequentially irradiated onto the main surface of the banknote BN on the side of the light receiving unit 113 (hereinafter referred to as surface A). The condenser lens 112 is composed of, for example, a rod lens array in which a plurality of rod lenses are arranged in the main scanning direction, and collects the light emitted from the light source 111 for reflection and reflected by the A side of the banknote BN. . The light-receiving unit 113 includes, for example, a linear image sensor in which a plurality of light-receiving elements (light-receiving pixels) are arranged in the main scanning direction. have For each light receiving element, for example, a silicon (Si) photodiode having sensitivity at least from the visible region to the infrared region with a wavelength of 1100 nm can be used. Each light-receiving element is mounted on the substrate 114 , receives light condensed by the condensing lens 112 , converts it into an electrical signal corresponding to the amount of incident light, and outputs the electrical signal to the substrate 114 . Each light-receiving element receives the light of each wavelength in accordance with the irradiation timing of the light of each wavelength from the light source 111 . The substrate 114 includes, for example, a drive circuit for driving the light receiving elements and a signal processing circuit for processing and outputting signals from the light receiving elements. The substrate 114 amplifies the output signal of the light receiving section 113 (each light receiving element), A/D-converts it into digital data, and outputs it.

The light source 111 irradiates at least infrared light with a plurality of wavelengths, for example, first to third infrared light with different peak wavelengths. The light source 111 may also emit visible light. As visible light, for example, red light (R), green light (G), blue light (B), white light (W) including these three colors of light, and the like can be used.

In the present embodiment, since the control unit 120 performs the same processing as the control unit 10a or 10b described in the first or second embodiment, it is possible to improve bill identification accuracy as in the first or second embodiment. is.

In the above embodiment, a case has been described in which the output data related to the light emitted from the light source and reflected by the banknote is used for the correction processing and the multiplication processing by the control unit. The output data may be used for correction processing or multiplication processing by the control unit.

Although the embodiments have been described above with reference to the drawings, the present disclosure is not limited to the above embodiments. Also, the configuration of each embodiment may be appropriately combined or changed without departing from the gist of the present disclosure.

As described above, the present disclosure is a technique useful for improving accuracy in identifying paper sheets.

1a, 1b, 100: Paper sheet identification devices 11a, 11b, 111: Light sources 13a, 13b, 113: Light receiving units 14a, 14b, 110: Optical line sensors 15a, 15b: Light guides 15aa, 15ba: Light guides End faces 17a, 17b: Light emitting elements 20a, 20b, 120: Control unit 112: Condensing lens 114: Substrate 130: Storage unit 140: Transport unit 300: Banknote processing device 301: Hopper 302: Reject unit 303: Operation unit 305: Display Units 306a to 306d: Stacking unit 311: Conveyance path BN: Banknote S: Identification object ROI _A : Area including identification object ROI _B : Area not including identification object Pix: Pixel

Claims (12)

A paper sheet identification device for identifying a paper sheet provided with an identification target,
a light source for irradiating light onto paper sheets;
a light-receiving unit that receives light coming from paper sheets;
A control unit that acquires output data of the light receiving unit,
The control unit
Acquiring first data that is output data of the light receiving unit corresponding to an area including an identification target and second data that is output data of the light receiving unit corresponding to an area not including the identification target ,
generating third data by correcting the first data with the second data;
A paper sheet identification device, wherein the paper sheet is identified based on the third data. The light source irradiates the paper sheet with light of multiple wavelengths,
The light receiving unit receives light of a plurality of wavelengths coming from paper sheets,
each of the first data and the second data includes data related to light of the plurality of wavelengths;
wherein the control unit generates third data related to light of multiple wavelengths by correcting each of the first data related to light of multiple wavelengths with corresponding second data related to light of the same wavelength;
2. The paper sheet identifying apparatus according to claim 1, wherein the paper sheet is identified based on the third data relating to the light of the plurality of wavelengths. The control unit controls first multiplication data obtained by multiplying data related to light of a first wavelength and data related to light of a second wavelength out of the first data related to the light of the multiple wavelengths, and the light of the multiple wavelengths. Calculate second multiplication data that is data obtained by multiplying data related to light of the first wavelength and the light of the second wavelength among the second data related to
generating fourth data obtained by correcting the first multiplication data with the second multiplication data;
3. The paper sheet identification device according to claim 2, wherein the paper sheet is identified based on the third data and the fourth data relating to the lights of the plurality of wavelengths. 4. The paper sheet identifying apparatus according to claim 1, wherein said control unit uses, as said second data, a representative value of output data of an area not including said identification object. The light source is
a rod-shaped light guide made of acrylic resin;
a light emitting element facing at least one of the two end surfaces of the light guide;
with
The light source is
5. The paper sheet identification device according to claim 1, wherein the paper sheet is irradiated with light through the light guide. The light source irradiates the paper sheet with linear light in the main scanning direction,
The light receiving unit receives linear light in a main scanning direction coming from paper sheets,
The paper sheet according to any one of claims 1 to 5, wherein the control unit uses, as the second data, output data corresponding to a position in the main scanning direction of the area containing the identification object. Class identifier. A paper sheet identification device for identifying a paper sheet provided with an identification target,
a light source that irradiates light of multiple wavelengths onto paper sheets;
a light receiving unit that receives light of multiple wavelengths coming from paper sheets;
a control unit that acquires output data related to the light of the plurality of wavelengths from the light receiving unit;
The control unit calculates multiplication data obtained by multiplying the data related to the light of the first wavelength and the data related to the light of the second wavelength out of the acquired output data related to the light of the plurality of wavelengths,
A paper sheet identification device, wherein the paper sheet is identified based on the output data relating to the light of the plurality of wavelengths and the multiplication data. The light source irradiates the paper sheet with infrared light,
The paper sheet identification device according to any one of claims 1 to 7, wherein the infrared light includes light with a wavelength of 850 nm or more and 950 nm or less. The light receiving unit receives light emitted from the light source and reflected by the paper sheet,
9. The paper sheet identifying apparatus according to claim 1, wherein said output data includes data relating to light reflected by paper sheets. Paper sheets to be identified include at least one of ink whose reflectance decreases as the wavelength increases in the infrared region and ink whose reflectance increases as the wavelength increases in the infrared region. 10. The paper sheet identification device according to any one of claims 1 to 9, comprising: A paper sheet identification method for identifying a paper sheet provided with an identification target,
a step of acquiring output data from a light receiving unit that receives light emitted from a light source and arriving from a paper sheet;
Acquiring first data that is output data of the light receiving unit corresponding to the area including the identification object and second data that is output data of the light receiving unit corresponding to the area not including the identification object a step;
generating third data by correcting the first data with the second data;
identifying paper sheets based on the third data;
A paper sheet identification method comprising: A paper sheet identification method for identifying a paper sheet provided with an identification target,
a step of acquiring output data related to light of multiple wavelengths from a light receiving unit that receives light of multiple wavelengths that is emitted from a light source and arrives from a paper sheet;
a step of calculating multiplication data, which is data obtained by multiplying the data relating to the light of the first wavelength and the second wavelength out of the acquired output data relating to the light of the plurality of wavelengths;
a step of identifying paper sheets based on the output data relating to light of multiple wavelengths and the multiplication data;
A paper sheet identification method comprising:

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