WO2019082251A1

WO2019082251A1 - Optical sensor, optical sensor module, and paper processing device

Info

Publication number: WO2019082251A1
Application number: PCT/JP2017/038226
Authority: WO
Inventors: 晶坊垣; 昌志西川; 高明森本
Original assignee: グローリー株式会社
Priority date: 2017-10-23
Filing date: 2017-10-23
Publication date: 2019-05-02

Abstract

In order to detect, with high accuracy, optical characteristics in an infrared region of a sheet of paper, this optical sensor used for detecting the optical characteristics comprises: a light-emitting unit having a light-emitting element corresponding to at least three infrared bands included in an infrared region with a wavelength of 1,100 nm or less; and a light-receiving unit having a light-receiving element that is sensitive to the at least three infrared bands. The light-receiving unit is configured so as to detect, using the light-receiving element, the intensity of light in each of the at least three infrared bands.

Description

Optical sensor, optical sensor module, and sheet processing apparatus

The present invention relates to an optical sensor for detecting optical characteristics in an infrared region, an optical sensor module including the optical sensor, and a sheet processing apparatus.

Conventionally, as a security feature for preventing forgery of banknotes, securities, and the like, an ink having a characteristic of reflection and absorption in an infrared region has been used. As a method of determining whether or not printing is performed using such an ink, Patent Documents 1 and 2 detect the reflection intensity of light of a predetermined wavelength band in the infrared region, and use as reference data A method of comparison is disclosed. The device described in Patent Document 1 detects the reflection intensity of a printed matter in a plurality of wavelength bands in the infrared region, and determines the presence or absence of printing with a predetermined ink by comparing with reference level data. The device described in Patent Document 2 determines the type of ink based on whether or not the reflection intensities of the ink obtained in a plurality of wavelength bands have a predetermined magnitude relationship.

For example, a photodiode is used as a sensor that detects light in the infrared region. If a photodiode made of indium gallium arsenide (InGaAs) is used, light can be detected in a wide wavelength range in the infrared range, but light in the visible range can not be detected. When a photodiode made of silicon (Si) is used, light in the visible region can be detected. When silicon is used, the upper limit of the wavelength of light that can be detected in the infrared region is theoretically 1100 nm and practically around 1000 nm. Patent Documents 3 and 4 disclose line sensors capable of acquiring an image in both the visible region and the near infrared region. These line sensors are configured by forming a circuit on silicon and linearly arranging photodiodes. While the sheet is being conveyed by the conveying device, the surface of the sheet is scanned by the line sensor to acquire an image of the sheet.

The line sensor of Patent Document 3 includes a light emitting unit using a plurality of LEDs having different light emission wavelengths as a light source, and a light receiving unit having a plurality of light receiving elements receiving light of each wavelength band using a band pass filter. . A plurality of light receiving elements simultaneously receive the light of each wavelength band reflected by the paper or the light of each wavelength transmitted through the paper simultaneously by irradiating the light of a plurality of wavelength bands toward the paper. Do. By acquiring data while conveying a sheet, it is possible to acquire a sheet image of each of a plurality of wavelength bands. In this case, since data of a plurality of types of paper sheet images having different wavelength bands are simultaneously acquired, the number of light receiving elements for each pixel is increased. For this reason, although the area of each light receiving element becomes small and the sensitivity becomes disadvantageous, there is an advantage that the corresponding pixels of each sheet image become data acquired at the same position on the sheet.

The line sensor of Patent Document 4 includes a light emitting unit using a plurality of LEDs having different light emission wavelength bands as light sources, and a light receiving unit having one light receiving element capable of receiving light of the wavelength of each light source. Light of a plurality of wavelength bands is sequentially emitted one by one, and one light receiving element sequentially receives light of each wavelength band. By acquiring data while conveying a sheet, it is possible to acquire a sheet image of each of a plurality of wavelength bands. In this case, since the data of a plurality of types of paper sheet images having different wavelength bands are sequentially acquired, the number of light receiving elements per pixel may be one. Therefore, although corresponding pixels of each sheet image are data acquired at different positions on the sheet, the area of the light receiving element can be increased, which is advantageous in sensitivity.

Japanese Patent Application Publication No. 2005-246821 Japanese Patent Application Laid-Open No. 6-217130 JP, 2016-53783, A Patent No. 5005760

There are various inks that exhibit characteristic optical characteristics in the infrared region, but in the prior art, there are cases where the optical characteristics of each ink can not be detected with high accuracy. For example, when the reflectance of each ink is different in a plurality of wavelength bands included in the infrared region, the above-described conventional techniques can not distinguish and detect each ink.

The present invention has been made to solve the above-mentioned problems of the prior art, and it is possible to accurately detect the optical characteristics of a sheet in the infrared region, an optical sensor module, and a sheet. It is in providing a processing apparatus.

In order to solve the problems described above and to achieve the object, the present invention is an optical sensor, and a light emitting unit having light emitting elements corresponding to at least three infrared wavelength bands included in an infrared region having a wavelength of 1100 nm or less And a light receiving unit having sensitivity to the at least three infrared wavelength bands, and a light receiving unit configured to detect the intensity of each of the at least three infrared wavelength bands.

Further, the present invention is characterized in that, in the above-mentioned invention, the light receiving section detects the intensity of the light of each of the at least three infrared wavelength bands with the same light receiving element.

The present invention is characterized in that, in the above-mentioned invention, the light receiving section detects the intensity of the light of the at least three infrared wavelength bands with at least three light receiving elements.

Further, according to the present invention, in the above invention, the light emitting portion further includes a light emitting element corresponding to at least one visible wavelength band included in a wavelength range of 400 to 700 nm, and the light receiving element further includes the visible wavelength band It is characterized by having sensitivity to

Further, the present invention is characterized in that, in the above-mentioned invention, the light receiving element is a silicon photodiode.

Further, the present invention is characterized in that, in the above-mentioned invention, the at least three infrared wavelength bands are included in an infrared region having a wavelength of 1000 nm or less.

Further, the present invention is characterized in that, in the above-mentioned invention, the at least three infrared wavelength bands are included in an infrared region having a wavelength of 760 nm or more.

The present invention is characterized in that, in the above-mentioned invention, the infrared region has a wavelength of 780 nm or more.

The present invention is characterized in that, in the above-mentioned invention, the infrared region has a wavelength of 760 nm or more.

The present invention is a light sensor module, comprising: the light sensor according to the above invention; and an output unit for outputting the intensity of light detected by the light sensor to the outside, wherein the light receiving unit of the light sensor is It has a structure in which a plurality of the light receiving elements are linearly arranged.

Further, according to the present invention, there is provided a sheet processing apparatus, wherein the optical sensor according to the above-described invention, a transport unit for transporting a sheet having security features, and a sheet transported by the transport unit by the optical sensor. And a determination unit that determines the authenticity of the security feature based on the light intensity of the at least three infrared wavelength bands acquired from the security feature of the type.

According to the present invention, the light of each wavelength band can be detected by irradiating the sheet with the light of each of the plurality of wavelength bands included in the infrared region. For example, even in the case where there is a sheet in which a plurality of types of ink having different reflectances in each wavelength band are used, the type of each ink can be specified.

FIG. 1 is a block diagram showing an outline of the configuration of a sheet processing apparatus. FIG. 2 is a schematic cross-sectional view for explaining the operation of the sheet processing apparatus. FIG. 3 is a schematic view showing the structure of the light emitting unit. FIG. 4 is a schematic view showing the structure of the light receiving unit. FIG. 5 is a schematic view showing the structure of a condensing lens. FIG. 6 is a timing chart showing the operation of the sensor unit. FIG. 7 is a view showing an example of a sheet having regions having different optical characteristics. FIG. 8 is a diagram for explaining a method of determining the type and authenticity of a sheet. FIG. 9 is a diagram for explaining another configuration example of the light receiving unit. FIG. 10 is a timing chart showing the operation of the sensor unit including the light receiving unit shown in FIG. FIG. 11 is a diagram for explaining yet another configuration example of the light receiving unit. FIG. 12 is a timing chart showing the operation of the sensor unit including the light receiving unit shown in FIG.

Hereinafter, preferred embodiments of an optical sensor, an optical sensor module, and a sheet processing apparatus according to the present invention will be described in detail with reference to the attached drawings. In the present embodiment, a sheet processing apparatus for examining optical characteristics of sheets will be described as an example. Here, the paper sheet is a sheet-like medium such as a gift card, a check, a security such as a bill, a banknote, and the like. As with paper banknotes and resin banknotes, the material of the paper sheet is not particularly limited, and may be paper, resin, or another material.

The range of the visible region is between 360 nm and 400 nm on the short wavelength side and between 760 nm and 830 nm on the long wavelength side, and the range of the infrared region is generally 1 mm longer than the wavelength in the visible region (For example, JIS Z 8113 lighting terms). Further, referring to IEC 60050-845: 1987, the lower limit value of IR-A is 780 nm. Therefore, in the present invention, the lower limit of the infrared region is set to 760 to 780 nm, but in the present embodiment, the lower limit of the infrared region is set to 780 nm.

FIG. 1 is a block diagram showing an outline of the configuration of a sheet processing apparatus. The sheet processing apparatus includes a sensor unit 1, a conveyance unit 60, a control unit 70, and a storage unit 80. The sensor unit 1 includes a light receiving unit 10 and a light emitting unit 20. The light emitting unit 20 includes a light source for irradiating the sheet with light of each of a plurality of wavelength bands in the visible region, and a light source for irradiating the sheet with light of each of a plurality of wavelength bands in the infrared region. The light receiving unit 10 includes light receiving elements that are irradiated to the paper sheets from the light sources of the light emitting unit 20 and detect the intensity of the light reflected by the paper sheets. That is, the light receiving element of the light receiving unit 10 is sensitive to the plurality of wavelength bands of the visible region and the plurality of wavelength bands of the infrared region that the light emitting unit 20 irradiates to the paper sheet.

The transport unit 60 rotationally drives a plurality of rollers, belts, and the like to transport paper sheets one by one along a transport path provided in the apparatus. The transport unit 60 includes a rotary encoder synchronized with the amount of rotation of a roller or the like, and outputs a pulse signal (hereinafter referred to as “mecha clock”) according to the transport distance of the sheet. The storage unit 80 is formed of a non-volatile storage device such as a semiconductor memory, and the detection data 81 and the determination data 82 are stored therein. The detection data 81 is data obtained by irradiating the light from the light emitting unit 20 toward the sheet transported by the transport unit 60 and detecting the light reflected by the sheet by the light receiving unit 10. The determination data 82 is data prepared in advance to determine the type, authenticity or the like of the sheet based on the data detected from the sheet.

The control unit 70 includes a conveyance control unit 71, a light emission control unit 72, a data acquisition unit 73, a determination unit 74, and an output unit 75. The transport control unit 71 controls the transport unit 60 to transport paper sheets along the transport path. The light emission control unit 72 controls the light emitting unit 20 to irradiate light of each of a plurality of wavelength bands toward the sheet transported by the transport unit 60. The data acquisition unit 73 controls the light receiving unit 10 to acquire data obtained by detecting the intensity of the light reflected by the sheet. The data acquisition unit 73 acquires data from the light receiving unit 10 via the substrate 40 (see FIG. 2). The cooperation of the conveyance control unit 71, the light emission control unit 72, and the data acquisition unit 73 causes the paper sheets to be irradiated with light of each of a plurality of wavelength bands in accordance with the timing at which the paper sheets are conveyed. The intensity of the light reflected by the class can be detected. The determination unit 74 compares the data acquired from the sheet by the data acquisition unit 73 with the data prepared in advance as the determination data 82 to determine the type, authenticity, and the like of the sheet. The output unit 75 outputs the data acquired by the data acquisition unit 73, the determination result by the determination unit 74, and the like to an external device.

FIG. 2 is a schematic cross-sectional view for explaining the operation of the sheet processing apparatus. FIG. 2 shows a cross section of the sensor unit 1 provided in the sheet processing apparatus as viewed from the side. The sheet processing apparatus transports the sheet received from the outside of the apparatus in the apparatus. Specifically, as shown in FIG. 2, the transport unit 60 transports the paper sheet 100 in the direction indicated by the arrow 200 along the transport path 61 provided in the apparatus. The transport path 61 is formed between the upper guide plate 61 a and the lower guide plate 61 b. The sensor unit 1 is disposed on the upper side of the transport path 61 so that the lower surface of the case 1a is flush with the lower surface of the upper guide plate 61a. In the case 1 a of the sensor unit 1, a light receiving unit 10 provided on a substrate 40, two light emitting units 20 (20 a and 20 b), and a condensing lens 30 are provided. One light emitting unit 20 a is disposed upstream of the light receiving unit 10 in the conveying direction, and the other light emitting unit 20 b is disposed downstream of the light receiving unit 10 in the conveying direction. The condensing lens 30 is disposed below the light receiving unit 10 and between the two light emitting

units

20 a and 20 b. A window 50 made of a transparent member is provided on the lower surface of the case 1a.

FIG. 3 is a schematic view showing the structure of the light emitting unit 20. As shown in FIG. As shown in FIG. 3A, the light emitting unit 20 is provided with a rod-shaped light guide 22 which is long in the main scanning direction (X-axis direction) perpendicular to the conveyance direction (Y-axis direction) of the paper sheet 100; And a light source 21 provided on the end face of the light 22. As shown in FIG. 3 (b), the light source 21 is provided with a plurality of light emitting elements 21 a such as LEDs. When the light emitting element 21a of the light source 21 emits light, the light enters the inside of the light guide 22 and the light guide 22 emits light uniformly. The length of the light guide 22 in the main scanning direction is longer than the length of the paper sheet 100 in the main scanning direction. Thereby, the light emitted from the light source 21 can be irradiated to the entire main scanning direction of the paper sheet 100 through the light guide 22.

The light source 21 emits light in three wavelength bands of red light, green light and blue light in the visible region. In order to irradiate the paper sheet 100 with three types of visible light having different wavelength bands, the light source 21 is a light emitting element 21a that emits red light with a peak wavelength of 650 nm, a light emitting element 21a that emits green light with a peak wavelength of 550 nm, It has a light emitting element 21a that emits blue light having a wavelength of 450 nm. Further, the light source 21 emits light in three wavelength bands of a first infrared light, a second infrared light, and a third infrared light, which have different wavelengths in the infrared region. In order to irradiate the paper sheet 100 with three types of infrared light having different wavelength bands, the light source 21 is a light emitting element 21a that emits a first infrared light having a peak wavelength of 800 nm and a second infrared light having a peak wavelength of 880 nm. And a light emitting element 21a that emits a third infrared light having a peak wavelength of 950 nm.

The light emitted from each light emitting element 21 a is light in a wavelength band including a peak wavelength and a wavelength near the peak wavelength. The width of this wavelength band is defined, for example, by the full width at half maximum of the spectrum of the light emitting element 21a. Moreover, the peak wavelength of each light emitting element 21a can be changed suitably. For example, the peak wavelengths of the light emitting elements 21a that emit the first to third infrared light may be changed in the infrared region depending on the detection target. In addition, the full width at half maximum of each light emitting element 21a can be changed as appropriate.

The light emission control unit 72 causes the light emitting element 21 a selected from the plurality of types of light emitting elements 21 a included in the light source 21 to emit light. That is, the light source 21 can be turned on to emit one or more of red light, green light, blue light, first infrared light, second infrared light, and third infrared light. The light emitted from the light source 21 is irradiated to the paper sheet 100 through the light guide 22.

FIG. 4 is a schematic view showing the structure of the light receiving unit 10. The light receiving unit 10 is a line sensor configured by arranging a plurality of light receiving elements 11 in the main scanning direction. Each light receiving element 11 is sensitive to each wavelength band of red light, green light, blue light, first infrared light, second infrared light, and third infrared light that can be emitted from the light emitting unit 20. Each light receiving element 11 receives light in the visible region and the infrared region, and outputs an electrical signal according to the intensity of the received light.

As each light receiving element 11, it is preferable to use a silicon (Si) photodiode having sensitivity from the visible region to the infrared region up to a wavelength of 1100 nm. In this case, the light in the infrared region that can be detected by each light receiving element has a wavelength in the range of 780 nm to 1100 nm. Therefore, the peak wavelengths of the first infrared light, the second infrared light, and the third infrared light are in this range.

FIG. 5 is a schematic view showing the structure of the condenser lens 30. As shown in FIG. The condenser lens 30 is a rod lens array in which a plurality of rod lenses 31 are linearly arranged in two rows in the main scanning direction. The rod lens condenses the light in the visible region and the light in the infrared region reflected by the paper sheet 100 on the light receiving element 11 of the light receiving unit 10.

The length of the light receiving unit 10 in the main scanning direction is longer than the length of the paper sheet 100 in the main scanning direction. The condenser lens 30 is provided corresponding to the light receiving element 11 that constitutes the light receiving unit 10. Thus, the light reflected by the paper sheet 100 is collected by the collecting lens 30 and received by the light receiving unit 10 in the entire main scanning direction of the paper sheet 100, and data relating to the reflected light is acquired. it can. The light emitting unit 20 emits light over the entire main scanning direction of the paper sheet 100, and the light receiving unit 10 receives light reflected along the entire main scanning direction of the paper sheet 100. By continuing the irradiation of light by the light emitting unit 20 and the light reception of light by the light receiving unit 10 while conveying the paper sheet 100, it is possible to acquire data relating to the reflected light for the entire surface of the paper sheet 100. it can

Specifically, the transport control unit 71 controls the transport unit 60 to transport the paper sheet 100 along the transport path 61 in the transport direction indicated by the arrow 200 as illustrated in FIG. 2. When the sheet 100 passes under the sensor unit 1 provided in the conveyance path 61, the light emission control unit 72 causes the light emitting unit 20 to emit light. The light of the light emitting unit 20 is transmitted through the window unit 50 and irradiated to the paper sheet 100 in the conveyance path 61. The light reflected by the sheet 100 is transmitted through the window 50 and is incident on the condenser lens 30. The condensing lens 30 condenses the incident light on the light receiving unit 10. The light receiving unit 10 receives the light collected by the collecting lens 30. The data acquisition unit 73 acquires data according to the intensity of the light received by the light receiving unit 10. Line data long in the main scanning direction can be obtained from data obtained from the plurality of light receiving elements 11 forming the light receiving unit 10. The data acquisition unit 73 continues acquisition of data while the conveyance unit 60 conveys the sheet 100. The data acquisition unit 73 stores the acquired data as the detection data 81 in the storage unit 80. The determination unit 74 refers to the data stored as the detection data 81 to determine the intensity of the light received by each light receiving element 11 of the light receiving unit 10, that is, the intensity of the light reflected by the partial area on the paper sheet 100. You can get

Next, the operation of the sensor unit 1 will be described. The sensor unit 1 irradiates the sheet 100 with red light, green light, blue light, first infrared light, second infrared light and third infrared light, and the light reflected by the sheet 100 To detect FIG. 6 is a timing chart showing the operation of the sensor unit 1. The sensor unit 1 executes six phases of phases 1 to 6 shown in FIG. 6 based on the oscillating mechanical clock output by the transport unit 60. While the paper sheet 100 conveyed by the conveyance unit 60 passes the detection position of the reflected light by the sensor unit 1, the sensor unit 1 repeatedly executes the cycle with phases 1 to 6 as one cycle. Thereby, the data acquisition unit 73 can acquire data relating to the reflected light from the entire surface of the paper sheet 100.

In phase 1, the light emission control unit 72 turns on only the red light emitting element 21a, that is, only the red light source ("R" in FIG. 6) of the light emitting unit 20 ("ON" in FIG. 6). While the light emitting unit 20 irradiates the sheet 100 with red light, each light receiving element 11 of the light receiving unit 10 receives the red light reflected by the sheet 100. The data acquisition unit 73 acquires red light data (“R-Data” in FIG. 6) from each light receiving element 11. In phase 2, the light emission control unit 72 turns on only the light emitting element 21a of green light, that is, only the green light source (G) 21. While the light emitting unit 20 irradiates the sheet with green light, the data acquiring unit 73 receives the green light reflected by the sheet 100 by each light receiving element 11 of the light receiving unit 10, and the green light data Get (G-Data). Further, the data acquisition unit 73 stores the red light data (R-Data) acquired in phase 1 in the storage unit 80 as detection data 81. In phase 3, the light emission control unit 72 turns on only the blue light emitting element 21a, that is, only the blue light source (B) 21. While the light emitting unit 20 irradiates the sheet with blue light, the data acquiring unit 73 receives the blue light reflected by the sheet 100 by each light receiving element 11 of the light receiving unit 10, and Get data (B-Data). Further, the data acquisition unit 73 stores the green light data (G-Data) acquired in phase 2 in the storage unit 80 as detection data 81. In phase 4, the light emission control unit 72 turns on only the light emitting element 21a of the first infrared light, that is, only the first infrared light source (IR1) 21. While the light emitting unit 20 irradiates the paper with the first infrared light, the data acquiring unit 73 receives the first infrared light reflected by the paper 100 by each light receiving element 11 of the light receiving unit 10 Then, data (IR1-Data) of the first infrared light is acquired. Further, the data acquisition unit 73 stores the blue light data (B-Data) acquired in phase 3 in the storage unit 80 as detection data 81. In phase 5, the light emission control unit 72 turns on only the light emitting element 21a of the second infrared light, that is, only the second infrared light source (IR2) 21. While the light emitting unit 20 irradiates the paper with the second infrared light, the data acquiring unit 73 receives the second infrared light reflected by the paper 100 by each light receiving element 11 of the light receiving unit 10. The second infrared light data (IR2-Data) is acquired. Further, the data acquisition unit 73 stores the first infrared light data (IR 1 -Data) acquired in phase 4 in the storage unit 80 as detection data 81. In the phase 6, the light emission control unit 72 turns on only the light emitting element 21a of the third infrared light, that is, only the third infrared light source (IR3) 21. While the light emitting unit 20 irradiates the paper with the third infrared light, the data acquiring unit 73 receives the third infrared light reflected by the paper 100 by each light receiving element 11 of the light receiving unit 10 The third infrared light data (IR3-Data) is acquired. Also, the data acquisition unit 73 stores the second infrared light data (IR2-Data) acquired in phase 5 in the storage unit 80 as detection data 81. Note that the third infrared light data (IR3-Data) acquired in phase 6 is stored in the storage unit 80 as detection data 81 at the time of processing of phase 1 of the next cycle performed subsequently. .

Thus, the sensor unit 1 sequentially irradiates the sheet 100 with light of red light, green light, blue light, first infrared light, second infrared light, and third infrared light to The light reflected by the class 100 is detected. Thereby, six types of data of red light data, green light data, blue light data, first infrared light data, second infrared light data, and third infrared light data are obtained.

For example, data of reflectance I (= Ir / Is) from reference intensity Is that is the intensity of light emitted from light emitting unit 20 at each position on paper sheet 100 and intensity Ir of light received by light receiving unit 10 You can get The data acquisition unit 73 obtains reflectance data from the entire surface of the paper sheet 100 by repeatedly executing phases 1 to 6 while the paper sheet 100 passes the detection position of the reflected light by the sensor unit 1. Can. Specifically, red light reflectance data, green light reflectance data, blue light reflectance data, first infrared light reflectance data, second infrared light reflectance data, and third infrared light Six types of reflectance data of light reflectance data are obtained. As the reference intensity Is, the intensity of the light received by the light receiving unit 10 by irradiating the light from the light emitting unit 20 to the reference medium may be used. As a reference medium at this time, for example, suitable paper sheets such as white paper and a resin sheet are defined and used.

Further, for example, an image of the paper sheet 100 can be generated from the data acquired by the light receiving unit 10. The data obtained by the light receiving unit 10 is line data obtained by the light receiving element 11 disposed immediately before the main scanning direction. The paper sheet 100 is conveyed, that is, scanned in the sub scanning direction, and from each line data obtained, the reflection intensity Ir or the reflectance I is converted to a pixel value to generate a reflection image of the entire paper sheet 100 can do. Specifically, a red light paper sheet image, a green light paper sheet image, a blue light paper sheet image, a first infrared light paper sheet image, and a second infrared light paper sheet image And six types of sheet images of the sheet image of the third infrared light are obtained.

The resolution data in the main scanning direction (X-axis direction) of the reflectance data and the sheet image is a resolution according to the size and number of the light receiving elements 11 forming the light receiving unit 10. On the other hand, the resolution in the sub-scanning direction (Y-axis direction) corresponds to the transport speed based on the mechanical clock of the transport unit 60.

Paper sheet 100 includes a plurality of regions having different optical characteristics. By detecting the optical characteristics of the entire surface of the paper sheet 100 using the sensor unit 1, the type, authenticity or the like of the paper sheet 100 can be determined. Hereinafter, a method of determining the type of paper sheet based on the optical characteristics of the infrared region will be described with reference to a specific example.

FIG. 7 is a view showing an example of a sheet 100 having regions having different optical characteristics. The paper sheet 100 shown in FIG. 7 includes four regions of a first region 101 to a fourth region 104 which exhibit characteristic reflection characteristics in the infrared region. The first area 101 is an area printed with infrared reflective ink that reflects infrared light. The fourth area 104 is an area printed with an infrared absorbing ink that absorbs infrared light. The second area 102 is an area printed with the special ink A exhibiting a characteristic reflection characteristic in the infrared area. The third area 103 is an area printed with the special ink B which exhibits a characteristic reflection characteristic different from the special ink A in the infrared area.

The transport control unit 71 controls the transport unit 60 to transport the paper sheet 100, and the light emission control unit 72 and the data acquisition unit 73 repeatedly execute the cycle shown in FIG. The data acquisition unit 73 outputs data of reflectance when each of the red light, green light, blue light, first infrared light, second infrared light and third infrared light is irradiated to the paper sheet 100, Acquired on the entire surface of leaves 100. The data acquisition unit 73 stores the acquired reflectance data as the detection data 81 in the storage unit 80.

The determination unit 74 determines the type and authenticity of the sheet 100 using the detection data 81 and the determination data 82 stored in the storage unit 80. The determination data 82 is a reference indicating the features of the infrared reflective ink in the first area 101, the special ink A in the second area 102, the special ink B in the third area 103, and the infrared absorbing ink in the fourth area 104. Contains data.

FIG. 8 is a diagram for explaining a method of determining the type and authenticity of the sheet 100. As shown in FIG. FIGS. 8A to 8C show examples of the reflectance obtained in the first area 101 to the fourth area 104 of the paper sheet 100. FIG. The vertical axis is the reflectance, and the horizontal axis is the wavelength band of the light irradiated to the paper sheet 100, which is a wavelength that represents the wavelength band such as the peak wavelength. That is, IR1 on the horizontal axis is the peak wavelength of the first infrared light and indicates the wavelength band of the first infrared light, IR2 is the peak wavelength of the second infrared light and the wavelength band of the second infrared light And IR3 is the peak wavelength of the third infrared light and indicates the wavelength band of the third infrared light.

FIG. 8A shows the reflectance curve 301 obtained in the first region 101, the reflectance curve 302 obtained in the second region 102, the reflectance curve 303 obtained in the third region 103, and the fourth region 104. The reflectance curve 304 obtained by FIG.

The determination unit 74 determines the reflectance 301a of the first infrared light (IR1), the reflectance 301b of the second infrared light (IR2), and the reflection of the third infrared light (IR3), which are obtained in the first region 101. It is determined which of the infrared reflective ink, the special ink A, the special ink B, and the infrared absorbing ink, which is prepared in advance as the determination data 82, the feature of the rate 301c matches. For example, based on the fact that the values of the reflectances 301a, 301b, and 301c obtained in the first area 101 fall within the predetermined range, the determination unit 74 prints the first area 101 with infrared reflective ink. It is determined that the area is Similarly, the determination unit 74 determines that the fourth area 104 is an area printed with infrared absorbing ink, based on the values of the reflectances 304a, 304b, and 304c obtained in the fourth area 104 and the fluctuation range. Do. That is, the determination unit 74 determines that the infrared reflection ink is used when the reflectance value is high and the fluctuation range is small, and determines that the infrared absorption ink is used when the reflectance value is low and the fluctuation range is small. .

However, the method of determining the region in which the infrared reflective ink is used and the region in which the infrared absorbing ink is used is not limited to this. For example, the determination may be performed using the fact that the reflectances of the first region 101 to the fourth region 104 have different values. For example, the determination unit 74 determines that the first region 101 having the maximum reflectance 301 b when irradiated with the second infrared light is a region printed with infrared reflective ink. In addition, the determination unit 74 determines that the fourth area 104 having the minimum reflectance 304 b is an area printed with the infrared absorbing ink.

After identifying the first area 101 printed with the infrared reflective ink and the fourth area 104 printed with the infrared absorbing ink in this manner, the determination unit 74 subsequently prints the second area 102 and the third area 103. Of the ink used in the

For example, it is assumed that the special ink A exhibits a downward-sloping reflectance curve in which the reflectance decreases as the wavelength of infrared light increases. On the other hand, it is assumed that the special ink B shows a reflectance curve rising upward to the right where the reflectance increases as the wavelength of infrared light increases.

As shown in FIG. 8A, in the second region 102, the reflectance 302a of the first infrared light (IR1) exhibits a value higher than the reflectance 302b of the second infrared light (IR2), and this reflectance Reference numeral 302 b indicates a value higher than the reflectance 302 c of the third infrared light (IR 3). That is, the reflectance decreases as the wavelength of infrared light increases. Based on this result, the determination unit 74 determines that the second area 102 is an area printed with the special ink A. In the third region 103, the reflectance 303a of the first infrared light (IR1) exhibits a value lower than the reflectance 303b of the second infrared light (IR2), and the reflectance 303b is a third infrared light ( It shows a value lower than the reflectance 303c of IR3). That is, the reflectance increases as the wavelength of infrared light increases. Based on the result, the determination unit 74 determines that the third area 103 is an area printed with the special ink B.

Even when inks different from the special ink A and the special ink B are used by acquiring the reflectances of the first infrared light, the second infrared light, and the third infrared light having different wavelengths, each ink Can be distinguished and detected. For example, as shown in FIG. 8B, in the second region 102, the second infrared light (the reflectance of the first infrared light (IR1) and the reflectance of the third infrared light (IR3) are compared with each other. In the third region 103, the special ink C showing the valley-shaped reflectance curve 402 with low reflectance of IR2) is used, and even when the special ink B showing the reflectance curve 303 rising rightward is used, 3 By comparing the reflectances of the two wavelength bands, they can be distinguished and detected.

Also, for example, as shown in FIG. 8C, in the second region 102, the special ink C showing the valley-shaped reflectance curve 402 is used, and in the third region 103, the first infrared light (IR1) Even when the special ink D showing a mountain-shaped reflectance curve 503 in which the reflectance of the second infrared light (IR2) is higher than the reflectance of the third infrared light (IR3) and the reflectance of the third infrared light (IR3) is used. These can be distinguished and detected by comparing the reflectances of the three wavelength bands.

As described above, the reflection is obtained by irradiating the paper sheet 100 with three types of infrared light of the first infrared light, the second infrared light, and the third infrared light having different wavelength bands to obtain the reflectance. The infrared reflection ink, the infrared absorption ink, and the special inks A to D having different rate waveforms can be separately detected.

The determination method for identifying the type of ink from the reflectance value and the characteristics of the reflection curve is not particularly limited. For example, each value of the reflectance of the first infrared light, the reflectance of the second infrared light, and the reflectance of the third infrared light may be a reference value of each reflectance prepared in advance for each ink and a predetermined range. The type of ink is determined based on whether or not there is a match. In addition, for example, the ratio of each value of the reflectance of the first infrared light, the reflectance of the second infrared light, and the reflectance of the third infrared light is the value of each reflectance prepared in advance for each ink. The type of ink is determined based on whether or not the ratio matches within a predetermined range. Also, for example, the magnitude relationship between the respective values of the reflectance of the first infrared light, the reflectance of the second infrared light, and the reflectance of the third infrared light is the value of each reflectance prepared in advance for each ink. The type of ink is determined on the basis of whether or not the magnitude relationship between the values and the predetermined relationship with each other matches. How to determine the characteristics such as the reflectance value, the ratio of the values, the magnitude relationship, etc. is appropriately set using the values and features that can distinguish the inks to be detected. .

The determination data 82 includes information indicating the relationship between the type of paper sheet 100 and the type of ink used in each of the areas 101 to 104. For example, after determining the type of ink used in each of the areas 101 to 104, the determination unit 74 determines the type of the sheet 100 with reference to the determination data 82. Also, for example, after the determination unit 74 first determines the type of the paper sheet 100 based on the data obtained in the visible region, etc., the determination data 74 refers to the determination data 82, and each type of paper sheet is selected. The type of ink that should be used for printing in the areas 101 to 104 is read out. Then, the determination unit 74 determines the authenticity of the paper sheet 100 based on whether or not the ink type actually detected in each of the areas 101 to 104 of the paper sheet 100 matches the read ink type. Determine

As described above, in each of the first region 101 to the fourth region 104, reflection characteristics of three types of infrared light of the first infrared light, the second infrared light, and the third infrared light having different wavelength bands are obtained. By examining, it is possible to determine the type of ink used for printing each region, such as infrared reflection ink, infrared absorption ink, and other special ink. Further, the type and authenticity of the sheet 100 can be determined based on the type of ink used in each area.

In FIG. 4, red light, green light, blue light, first infrared light, second infrared light and third infrared light are sequentially emitted from the light emitting unit 20 to the paper sheet 100 to receive light. The example which light-receives by each light receiving element 11 which forms the part 10 was shown. In this example, all types of light having different wavelength bands are received by one light receiving element 11. For example, when an image of a sheet 100 is generated by emitting red light, each pixel data forming the sheet image is data acquired by one light receiving element 11. Similarly, with regard to paper sheets of green light, blue light, first infrared light, second infrared light and third infrared light, each pixel data forming a paper sheet image is one light receiving element It becomes the data acquired in 11.

The configuration of the light receiving unit 10 is not limited to the example shown in FIG. FIG. 9 is a diagram for explaining another configuration example of the light receiving unit 10. FIG. 11 is a diagram for explaining yet another configuration example of the light receiving unit 10. Hereinafter, these configuration examples will be described.

The light receiving unit 10 illustrated in FIG. 9A is a line sensor configured by arranging a plurality of element units 111 in the main scanning direction. As shown in FIGS. 9B and 9C, each element section 111 is formed by arranging four square light receiving elements 112 (112a to 112d) in two rows and two columns. Bandpass filters 113 (113a to 113d) are attached to the respective light receiving elements 112a to 112d. Thus, the light receiving elements 112a to 112d receive only the light of the predetermined wavelength band transmitted through the band pass filters 113a to 113d. Specifically, the band pass filter 113a transmits red light in a wavelength band of 600 to 700 nm, and the light receiving element 112a receives red light in this wavelength band. The band pass filter 113b transmits green light in a wavelength band of 500 to 600 nm, and the light receiving element 112b receives green light in this wavelength band. The band pass filter 113c transmits blue light in a wavelength band of 400 to 500 nm, and the light receiving element 112c receives blue light in this wavelength band. The band pass filter 113d transmits infrared light in a wavelength band of 700 to 1100 nm, and the light receiving element 112d receives infrared light in this wavelength band.

FIG. 10 is a timing chart showing the operation of the sensor unit 1 including the light receiving unit 10 shown in FIG. While the sheet 100 transported by the transport unit 60 passes the detection position by the sensor unit 1, the sensor unit 1 repeatedly executes the cycle with phases 1 to 4 shown in FIG. 10 as one cycle. Thereby, the data acquisition unit 73 can acquire data relating to the reflected light from the entire surface of the paper sheet 100.

In the timing chart shown in FIG. 10, the red light, the green light, and the blue light are simultaneously irradiated to the paper sheet 100, and the data relating to the reflected light is provided to the plurality of light receiving elements 112a to The point acquired simultaneously using 112c differs from the timing chart shown in FIG.

Specifically, in phase 1, the light emission control unit 72 simultaneously turns on the red light source (R) 21, the green light source (G) 21, and the blue light source (B) 21. While the red light, the green light and the blue light are irradiated to the paper sheet 100, the light receiving unit 10 receives the red light, the green light and the blue light reflected by the paper sheet 100, respectively. Light is received simultaneously at 112c. The data acquisition unit 73 acquires red light data (R-Data), green light data (G-Data) and blue light data (B-Data) from the respective light receiving elements 112a to 112c. In phase 2, the light emission control unit 72 turns on only the first infrared light source (IR1) 21. While the light emitting unit 20 irradiates the paper with the first infrared light, the data acquiring unit 73 receives the first infrared light reflected by the paper 100 with the light receiving element 112 d, and Acquire infrared light data (IR1-Data). In addition, the data acquisition unit 73 stores the red light data (R-Data), the green light data (G-Data), and the blue light data (B-Data) acquired in phase 1 in the storage unit 80 as the detection data 81. Do. In phase 3, the light emission control unit 72 turns on only the second infrared light source (IR2) 21. While the light emitting unit 20 irradiates the paper with the second infrared light, the data acquiring unit 73 receives the second infrared light reflected by the paper 100 with the light receiving element 112 d, Acquire infrared light data (IR2-Data). Further, the data acquisition unit 73 stores the first infrared light data (IR 1 -Data) acquired in phase 2 in the storage unit 80 as detection data 81. In the phase 4, the light emission control unit 72 turns on only the third infrared light source (IR3) 21. While the light emitting unit 20 irradiates the paper with the third infrared light, the data acquiring unit 73 receives the third infrared light reflected by the paper 100 with the light receiving element 112 d, Acquire infrared light data (IR1-Data). Further, the data acquisition unit 73 stores the second infrared light data (IR2-Data) acquired in phase 3 in the storage unit 80 as detection data 81. The third infrared light data (IR3-Data) acquired in phase 4 is stored in the storage unit 80 as detection data 81 at the time of processing of phase 1 of the next cycle performed subsequently. . By repeatedly acquiring data while the paper sheet 100 passes the detection position by the sensor unit 1, data relating to the reflected light can be acquired on the entire surface of the paper sheet 100.

Thus, even in the light receiving unit 10 having the configuration shown in FIG. 9, red light, green light, blue light, and the first infrared light reflected by the paper sheet 100 are the same as in the light receiving unit 10 having the configuration shown in FIG. The light, the second infrared light, and the third infrared light can be detected to obtain data of each wavelength band. As a result, as described above, the type of ink used in the partial area on the sheet 100 can be determined, and the type and authenticity of the sheet 100 can be determined.

The light receiving unit 10 illustrated in FIG. 11A is a line sensor configured by arranging a plurality of element units 211 in the main scanning direction. As shown in FIGS. 11B and 11C, the element portion 211 has a square shape, and is formed by arranging three rectangular light receiving elements 212 (212a to 212c).

Band pass filters 213 (213a to 213c) are attached to the respective light receiving elements 212a to 212c. Thus, the light receiving elements 212a to 212c receive only the light of the predetermined wavelength band transmitted through the band pass filters 213a to 213c. Specifically, the band pass filter 213a transmits red light and infrared light in a wavelength band of 600 to 1100 nm, and the light receiving element 212a receives red light and infrared light in this wavelength band. The band pass filter 213b transmits green light in a wavelength band of 500 to 600 nm, and the light receiving element 212a receives green light in this wavelength band. The band pass filter 213c transmits blue light in a wavelength band of 400 to 500 nm, and the light receiving element 212c receives blue light in this wavelength band.

FIG. 12 is a timing chart showing the operation of the sensor unit 1 including the light receiving unit 10 shown in FIG. While the paper sheet 100 transported by the transport unit 60 passes the detection position by the sensor unit 1, the sensor unit 1 repeatedly executes the cycle with phases 1 to 4 shown in FIG. 12 as one cycle. Thereby, the data acquisition unit 73 can acquire data relating to the reflected light from the entire surface of the paper sheet 100.

The timing chart shown in FIG. 12 is that the same light receiving element 212a receives data relating to the reflected light when the infrared light, the first infrared light, the second infrared light and the third infrared light are irradiated, This is different from the timing chart shown in FIG.

Specifically, in phase 1, the light emission control unit 72 simultaneously turns on the red light source (R) 21, the green light source (G) 21, and the blue light source (B) 21. While the red light, the green light and the blue light are irradiated to the paper sheet 100, the light receiving unit 10 receives the red light, the green light and the blue light reflected by the paper sheet 100, respectively. Light is received simultaneously at 212c. The data acquisition unit 73 acquires red light data (R-Data), green light data (G-Data) and blue light data (B-Data) from the respective light receiving elements 212a to 212c. In phase 2, the light emission control unit 72 turns on only the first infrared light source (IR1) 21. While the light emitting unit 20 irradiates the paper with the first infrared light, the data acquiring unit 73 receives the first infrared light reflected by the paper 100 with the light receiving element 212 a, and Acquire infrared light data (IR1-Data). In addition, the data acquisition unit 73 stores the red light data (R-Data), the green light data (G-Data), and the blue light data (B-Data) acquired in phase 1 in the storage unit 80 as the detection data 81. Do. In phase 3, the light emission control unit 72 turns on only the second infrared light source (IR2) 21. While the light emitting unit 20 irradiates the paper with the second infrared light, the data acquiring unit 73 receives the second infrared light reflected by the paper 100 with the light receiving element 212 a, and Acquire infrared light data (IR2-Data). Further, the data acquisition unit 73 stores the first infrared light data (IR 1 -Data) acquired in phase 2 in the storage unit 80 as detection data 81. In the phase 4, the light emission control unit 72 turns on only the third infrared light source (IR3) 21. While the light emitting unit 20 irradiates the paper with the third infrared light, the data acquiring unit 73 receives the third infrared light reflected by the paper 100 with the light receiving element 212 a, and Acquire infrared light data (IR1-Data). Further, the data acquisition unit 73 stores the second infrared light data (IR2-Data) acquired in phase 3 in the storage unit 80 as detection data 81. The third infrared light data (IR3-Data) acquired in phase 4 is stored in the storage unit 80 as detection data 81 at the time of processing of phase 1 of the next cycle performed subsequently. . By repeatedly acquiring data while the paper sheet 100 passes the detection position by the sensor unit 1, data relating to the reflected light can be acquired on the entire surface of the paper sheet 100.

Thus, even in the light receiving unit 10 having the configuration shown in FIG. 11, red light, green light, blue light, and first red reflected by the paper sheet 100 are the same as in the light receiving unit 10 having the configuration shown in FIG. The ambient light, the second infrared light, and the third infrared light can be detected to obtain data of each wavelength band. As a result, as described above, the type of ink used in the partial area on the sheet 100 can be determined, and the type and authenticity of the sheet 100 can be determined.

Although the example which provides one sensor part 1 above the conveyance path 61 was shown in this embodiment as shown in FIG. 2, the number and the arrangement position of the sensor part 1 are not limited to this. For example, the sensor unit 1 may be disposed below the transport path 61, and data relating to the reflected light may be acquired on both the upper surface and the lower surface of the paper sheet 100. Further, in addition to the configuration shown in FIG. 2, an embodiment in which the light receiving unit 10 is disposed below the transport path 61 and in addition to the intensity of the reflected light described above, the intensity of light transmitted through the paper sheet 100 is detected. It may be

In the present embodiment, the peak wavelength is used as the representative value of the wavelength band, but the central wavelength of the wavelength band may be used. Specifically, the central value of the full width at half maximum of the wavelength band may be used as the central wavelength representing the wavelength band.

In the present embodiment, the range in which the silicon (Si) photodiode can detect in the infrared region is 780 nm to 1100 nm, and the peak wavelengths of the first infrared light, the second infrared light, and the third infrared light are in this range. Although the case has been described, it is not essential that each peak wavelength or each central wavelength be within this range. All or a part of each wavelength band of the first infrared light, the second infrared light, and the third infrared light is included in the range of 780 nm to 1100 nm in which the silicon (Si) photodiode can detect in the infrared region. If so, it is possible to detect the light intensity in each of a plurality of infrared wavelength bands. For example, if the center wavelength of the third infrared light is 1120 nm and the full width at half maximum is 100 nm, it is possible to detect the intensity of the light in the wavelength band of the third infrared light.

The upper limit of the wavelength detectable by the silicon (Si) photodiode is theoretically 1100 nm, but the sensitivity near the upper limit is small. Therefore, the first infrared light, the second infrared light and the second infrared light can be detected in the range of 780 nm to 1000 nm. All or part of each wavelength band of the third infrared light may be included.

Furthermore, it is desirable that the wavelength band of the infrared light to be irradiated be 780 nm or more of the lower limit of the infrared region. This is because if the visible range is included in the wavelength band of infrared light, it is affected by the ink such as red ink which is close to the infrared range and has no feature in the infrared range. In order to avoid this influence, for example, when the central wavelength of the first infrared light is 800 nm, it is preferable to design the light source so that the full width at half maximum is 40 nm or less.

The wavelength band to which the light receiving element receiving infrared light has sensitivity corresponding to the first infrared light, the second infrared light and the third infrared light irradiated to the paper sheet 100 is the lower limit of the infrared region Of 780 nm or more is desirable. When the visible region is included in the wavelength band in which the light receiving element has sensitivity, the light receiving element is influenced by the ink such as red ink which is close to the infrared region and has no feature in the infrared region. In order to avoid this influence, for example, in the light receiving sensitivity of the light receiving element 112d that receives infrared light, the band pass filter 113d may be designed so that the lower limit value of the full width at half maximum is 780 nm or more. In addition, the lower limit of the wavelength transmitted by the band pass filter 113d may be 780 nm or more.

In the present embodiment, an example in which the intensity of light is detected by the same light receiving element in each of a plurality of infrared wavelength bands has been described, but a plurality of light receiving elements provided with band pass filters corresponding to each of a plurality of infrared wavelength bands The light intensity may be detected by At this time, the infrared light source may be provided for each infrared wavelength band, or one infrared light source capable of emitting infrared light widely corresponding to each infrared wavelength band may be used.

In the present embodiment, an example in which the light intensity is detected in three infrared wavelength bands has been described, but the infrared wavelength band for detecting the light intensity may be four or more depending on the detection target.

As described above, according to the sensor unit 1 according to the present embodiment, it is possible to irradiate a sheet with a plurality of infrared light of different wavelengths and to investigate the optical characteristics of the sheet. For example, by irradiating paper sheets with three types of infrared light having different wavelengths, it is possible to distinguish and detect a plurality of types of ink having characteristic optical characteristics in the infrared region.

As described above, the light sensor, the light sensor module, and the sheet processing apparatus according to the present invention are useful for detecting the optical characteristics of the sheet in the infrared region with high accuracy.

DESCRIPTION OF SYMBOLS 1 sensor unit 10

light receiving unit

11, 112, 212 light receiving element 20 light emitting unit 21 light source 21a light emitting element 22 light guiding member 30 light collecting member 31 rod lens 40 substrate 50 window unit 60 conveyance unit 61 conveyance path 70 control unit 71 conveyance control unit 72 light emission control unit 73 data acquisition unit 74 determination unit 75 output unit 80

storage unit

111, 211

element unit

113, 213 band pass filter 211 element unit 212 light receiving element

Claims

A light emitting portion having a light emitting element corresponding to at least three infrared wavelength bands included in an infrared region having a wavelength of 1100 nm or less;
An optical sensor comprising: a light receiving element having sensitivity to the at least three infrared wavelength bands; and a light receiving section for detecting the intensity of light of each of the at least three infrared wavelength bands.
The optical sensor according to claim 1, wherein the light receiving unit detects the intensity of light in each of the at least three infrared wavelength bands with the same light receiving element.
The optical sensor according to claim 1, wherein the light receiving unit detects the intensity of the light in the at least three infrared wavelength bands with at least three light receiving elements.
The light emitting unit further includes a light emitting element corresponding to at least one visible wavelength band included in a wavelength range of 400 to 700 nm,
The light sensor according to any one of claims 1 to 3, wherein the light receiving element is further sensitive to the visible wavelength band.
The light sensor according to any one of claims 1 to 4, wherein the light receiving element is a silicon photodiode.
The optical sensor according to any one of claims 1 to 5, wherein the at least three infrared wavelength bands are included in an infrared region having a wavelength of 1000 nm or less.
The light sensor according to claim 6, wherein the at least three infrared wavelength bands are included in an infrared region having a wavelength of 760 nm or more.
The optical sensor according to any one of claims 1 to 5, wherein the infrared region has a wavelength of 780 nm or more.
The optical sensor according to claim 8, wherein the infrared region has a wavelength of 760 nm or more.
An optical sensor according to any one of claims 1 to 9;
And an output unit for outputting the intensity of light detected by the light sensor to the outside,
An optical sensor module, wherein the light receiving portion of the optical sensor has a structure in which a plurality of the light receiving elements are linearly arranged.
An optical sensor according to any one of claims 1 to 9;
A transport unit for transporting a sheet having security features;
And a determination unit that determines the authenticity of the security feature based on the light intensity of the at least three infrared wavelength bands acquired from the security feature of the paper sheet transported by the transport unit by the optical sensor. A paper processing apparatus characterized in that.