Paper sheet identification device, paper sheet processing device, and paper sheet identification method

Abstract

To provide a paper sheet identification apparatus, a paper sheet processing device, and a paper sheet identification method for enabling a laminated bill to be detected with high accuracy.SOLUTION: Provided is a paper sheet identification apparatus that identifies a paper sheet, including: an image acquisition unit that irradiates the paper sheet with excitation light to receive fluorescent light generated from the paper sheet, thereby acquiring a fluorescent image of the paper sheet; and a control unit that calculates a fluorescent light level inherent in the paper sheet from the fluorescent image acquired by the image acquisition unit, extracts an abnormal area in the fluorescent image based on the fluorescent light level, and identifies whether or not the paper sheet is a laminated bill based on the abnormal area.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a paper sheet recognition device, a paper sheet processing device, and a paper sheet recognition method. [Background technology]

[0002] Conventionally, processing devices that process banknotes, gift certificates, checks, securities, etc. have been required to detect abnormal paper sheets such as cut and pasted paper sheets, torn paper sheets, and even paper sheets with graffiti on them.

[0003] A cut and pasted sheet is a sheet made by pasting together pieces of paper from one or more sheets using tape, glue, adhesive, etc. Hereinafter, cut and pasted sheets may be abbreviated as pasted sheets.

[0004] Regarding the detection of bonded notes that are stuck together using tape, glue, or adhesive, Patent Document 1 discloses that glossy tape such as mending tape fluoresces in the visible light when ultraviolet light, for example, ultraviolet light with a central wavelength of 365 nm, is irradiated onto the paper sheet. This characteristic is used to obtain a fluorescent image and identify the bonded notes. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-257395 Summary of the Invention [Problem to be solved by the invention]

[0006] However, for paper sheets such as banknotes, the amount of fluorescence emitted by the banknotes tends to increase depending on the degree of circulation. Specifically, as the banknotes are circulated in the market, they become stained with fingerprints and other dirt, causing the stained areas to fluoresce, and the fingerprints can cause the entire banknote to fluoresce. In addition, the amount of fluorescence emitted by tape, glue, adhesive, etc. attached to the joints of bonded notes can be very small. This poses a problem in that it is difficult to identify abnormal areas at bonded points using tape, glue, adhesive, etc. using a threshold value that uses absolute values.

[0007] The present disclosure has been made in consideration of the above-mentioned current situation, and aims to provide a paper sheet recognition device, a paper sheet processing device, and a paper sheet recognition method that are capable of detecting stuck sheets with high accuracy. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems and achieve the object, (1) a paper sheet identification device according to a first aspect of the present disclosure is a paper sheet identification device that identifies paper sheets, and includes an image acquisition unit that acquires a fluorescent image of the paper sheet by irradiating the paper sheet with excitation light and receiving fluorescence emitted from the paper sheet, and a control unit that calculates a fluorescence level specific to the paper sheet from the fluorescent image acquired by the image acquisition unit, extracts an abnormal area in the fluorescent image based on the fluorescence level, and identifies whether the paper sheet is a laminated note based on the abnormal area.

[0009] (2) In the paper sheet identification device described in (1) above, the control unit may calculate a threshold value for abnormal brightness values ​​in the fluorescent image from the fluorescent level, and may extract pixel areas in the fluorescent image that exceed the threshold value as the abnormal area.

[0010] (3) In the paper sheet identification device described in (1) or (2) above, the control unit may extract the abnormal area by scanning the fluorescent image in at least one direction selected from the main scanning direction, the sub-scanning direction, and an oblique direction forming a predetermined angle with respect to the main scanning direction and the sub-scanning direction.

[0011] (4) In the paper sheet recognition device described in (3) above, the control unit may extract the abnormal area by scanning the fluorescent image in each of the main scanning direction, the sub-scanning direction, and the diagonal direction.

[0012] (5) A paper sheet processing apparatus according to a second aspect of the present disclosure includes the paper sheet recognition device according to any one of (1) to (4) above.

[0013] (6) Furthermore, a paper sheet identification method according to a third aspect of the present disclosure is a paper sheet identification method for identifying paper sheets, and includes an image acquisition step of acquiring a fluorescent image of the paper sheet by irradiating the paper sheet with excitation light and receiving fluorescence emitted from the paper sheet; a fluorescence level calculation step of calculating a fluorescence level specific to the paper sheet from the fluorescent image acquired in the image acquisition step; an abnormal region extraction step of extracting an abnormal region in the fluorescent image based on the fluorescence level; and an identification step of identifying whether the paper sheet is a laminated note or not based on the abnormal region.

[0014] (7) In the paper sheet recognition device described in (6) above, the abnormal area extraction step may calculate a threshold value for abnormal brightness values ​​in the fluorescent image from the fluorescent level, and extract pixel areas in the fluorescent image that exceed the threshold value as the abnormal area.

[0015] (8) In the paper sheet identification device described in (6) or (7) above, the abnormal area extraction step may extract the abnormal area by scanning the fluorescent image in at least one direction selected from the main scanning direction, the sub-scanning direction, and an oblique direction forming a predetermined angle with respect to the main scanning direction and the sub-scanning direction.

[0016] (9) In the paper sheet recognition device described in (8) above, the abnormal area extraction step may extract the abnormal area by scanning the fluorescent image in each of the main scanning direction, the sub-scanning direction, and the diagonal direction. [Effects of the Invention]

[0017] According to the present disclosure, it is possible to provide a paper sheet recognition device, a paper sheet processing device, and a paper sheet recognition method that are capable of detecting stuck notes with high accuracy. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a schematic diagram illustrating an example of the configuration of a paper sheet recognition device according to a first embodiment, showing a banknote transport path as viewed from the side. FIG. [Figure 2] 1 is a block diagram illustrating an example of the configuration of a paper sheet recognition device according to a first embodiment. [Figure 3] FIG. 1 is a schematic diagram illustrating an example of the configuration of a paper sheet recognition device according to a first embodiment, as viewed from an oblique direction. [Figure 4] FIG. 2 is a schematic diagram for explaining the process of extracting an abnormal area by scanning a fluorescent image of a banknote in the main scanning direction in the first embodiment. [Figure 5] FIG. 10 is a schematic diagram for explaining the process of extracting an abnormal area by scanning a fluorescent image of a banknote in the sub-scanning direction in the first embodiment. [Figure 6] FIG. 10 is a schematic diagram for explaining the process of extracting an abnormal area by scanning a fluorescent image of a banknote in an oblique direction (+45°) in the first embodiment. [Figure 7] FIG. 10 is a schematic diagram for explaining the process of extracting an abnormal area by scanning a fluorescent image of a banknote in an oblique direction (−45°) in the first embodiment. [Figure 8] 5 is a flowchart illustrating an example of an operation of the paper sheet recognition device according to the first embodiment. [Figure 9] FIG. 10 is a schematic perspective view showing the appearance of an example of a paper sheet processing apparatus according to a second embodiment. [Figure 10] FIG. 10 is a block diagram illustrating an example of the configuration of a paper sheet processing apparatus according to a second embodiment. [Figure 11] FIG. 10 is a block diagram illustrating an example of the configuration of a paper sheet recognition device according to a second embodiment. [Figure 12] 10 is a cross-sectional view illustrating an example of the configuration of an image acquisition unit included in a paper sheet recognition device according to a second embodiment. FIG. [Figure 13] 10 is a perspective view illustrating an example of the configuration of a light receiving section included in an image acquisition section according to a second embodiment. FIG. [Figure 14] 10 is a schematic diagram showing wavelength characteristics of a color resist of a light receiving unit provided in an image acquisition unit according to the second embodiment. FIG. [Figure 15] FIG. 11 is a schematic diagram showing an example of a fluorescent image of a banknote before rotation correction by a pre-determination processing unit in the second embodiment. [Figure 16] FIG. 11 is a schematic diagram showing an example of a fluorescent image of a banknote after rotation correction by a pre-determination processor in the second embodiment. [Figure 17] FIG. 10 is a schematic diagram for explaining the process of determining fluorescence abnormalities in the entire banknote by the fluorescence abnormality determination unit in the second embodiment. [Figure 18] FIG. 10 is a schematic diagram showing an example of a fluorescence image of a banknote determined to have an abnormality in fluorescence throughout the entire banknote in the second embodiment. [Figure 19] 10 is a schematic diagram for explaining the process of determining a fluorescence abnormality in a mask area by a mask area determination unit in the second embodiment. FIG. [Figure 20] FIG. 11 is a schematic diagram showing an example of a fluorescent image of a banknote in which a mask area is determined to have a fluorescent abnormality in the second embodiment. [Figure 21] FIG. 10 is a schematic diagram for explaining the process of extracting an abnormal area by scanning a fluorescent image of a banknote in the main scanning direction in the second embodiment. [Figure 22] FIG. 10 is a schematic diagram for explaining the process of extracting an abnormal area by scanning a fluorescent image of a banknote in the sub-scanning direction in the second embodiment. [Figure 23] FIG. 10 is a schematic diagram for explaining the process of extracting an abnormal area by scanning a fluorescent image of a banknote in an oblique direction (+45°) in the second embodiment. [Figure 24] FIG. 10 is a schematic diagram for explaining the process of extracting an abnormal area by scanning a fluorescent image of a banknote in an oblique direction (−45°) in the second embodiment. [Figure 25] FIG. 11 is a schematic diagram showing an example of a fluorescent image of a banknote determined to have a fluorescent abnormality by scanning in the main scanning direction in the second embodiment. [Figure 26] FIG. 11 is a schematic diagram showing an example of a fluorescent image of a banknote determined to have a fluorescent abnormality by scanning in the sub-scanning direction in the second embodiment. [Figure 27] FIG. 10 is a schematic diagram showing an example of a fluorescent image of a banknote determined to have a fluorescent abnormality by scanning in an oblique direction (+45°) in the second embodiment. [Figure 28] FIG. 10 is a schematic diagram showing an example of a fluorescent image of a banknote determined to have a fluorescent abnormality by scanning in an oblique direction (−45°) in the second embodiment. [Figure 29] 10 is a first half of a flowchart illustrating an example of a fluorescence abnormality determination process of the paper sheet recognition device according to the second embodiment. [Figure 30] This is the second half of the flowchart shown in FIG. 29. [Figure 31] FIG. 11 is a schematic diagram showing an example of a color image obtained by irradiating visible light onto a banknote with adhesive in the third embodiment. [Figure 32] 32 is a schematic diagram of a color image obtained by irradiating the banknote shown in FIG. 31 with excitation light of a specific wavelength. [Figure 33] FIG. 10 is a cross-sectional view illustrating an example of the configuration of an image acquisition sensor unit included in the paper sheet recognition device according to the third embodiment. [Figure 34] FIG. 10 is a plan view schematically illustrating an example of the configuration of a substrate included in the image acquisition sensor unit according to the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0019]

[0014] Hereinafter, embodiments of a paper sheet recognition device, a paper sheet processing device, and a paper sheet recognition method according to the present disclosure will be described in detail with reference to the drawings. Although various types of paper sheets, such as banknotes, checks, gift certificates, promissory notes, forms, securities, and card-like media, can be applied to the present disclosure, the following description will be given using an example of a device for banknotes.

[0020] In the following description, the same reference numerals are used in common between different drawings to designate the same parts or parts having similar functions, and repeated explanations thereof will be omitted. In addition, the drawings explaining the structure show XYZ coordinate systems that are orthogonal to each other as appropriate.

[0021] (Embodiment 1) The configuration of the paper sheet recognition device according to this embodiment will be described with reference to Fig. 1. Fig. 1 is a schematic diagram illustrating an example of the configuration of the paper sheet recognition device according to embodiment 1, and is a diagram showing a banknote transport path as seen from the side. Fig. 2 is a block diagram illustrating an example of the configuration of the paper sheet recognition device according to embodiment 1.

[0022] As shown in Figures 1 and 2, the paper sheet recognition device 1 of this embodiment is a device that can recognize banknotes BN as paper sheets, in particular detect laminated notes, and is equipped with an image acquisition unit 10 and a control unit 20.

[0023] The paper sheet recognition device 1 may also include a storage unit configured from a storage device such as a semiconductor memory (RAM or ROM) or a hard disk.

[0024] The image acquisition unit 10 acquires a fluorescent image (image data based on fluorescence) of the banknote BN by irradiating the banknote BN with excitation light (for example, ultraviolet light) and receiving the fluorescent light emitted from the banknote BN.

[0025] The wavelength band of the fluorescence emitted from the banknote BN is not particularly limited, and may be, for example, the visible range or the infrared range.

[0026] The image acquisition unit 10 may also receive fluorescence emitted from the banknote BN in multiple wavelength bands. Specifically, the image acquisition unit 10 may receive fluorescence emitted from the banknote BN in at least one of the red wavelength band (approximately 600 nm to 700 nm), the green wavelength band (approximately 500 nm to 600 nm), and the blue wavelength band (approximately 400 nm to 500 nm). In this case, at least one of an R image due to red, a G image due to green, and a B image due to blue is acquired as the fluorescence image of the banknote BN. The image acquisition unit 10 may also receive fluorescence emitted from the banknote BN in each of the wavelength bands of the above three colors. In this case, three types of fluorescence images of the banknote BN are acquired: an R image due to red, a G image due to green, and a B image due to blue.

[0027] 1, the image acquisition unit 10 may include a light source 11 that irradiates light onto the banknote BN and a light receiving unit 13 that receives fluorescence emitted from the banknote BN. The banknote BN to be recognized may be transported in the X direction within an XY plane.

[0028] The light source 11 is provided on the same side of the banknote BN as the light receiving unit 13. For example, the light source 11 irradiates one main surface (hereinafter referred to as surface A) of the banknote BN with excitation light, and the light receiving unit 13 receives fluorescence emitted from surface A of the banknote BN.

[0029] A light source 11 and a light receiving unit 13 may also be provided on the other main surface (hereinafter referred to as surface B) of the banknote BN in a similar manner, and the fluorescence emitted from surface B of the banknote BN may be received. In this way, the image acquisition unit 10 may acquire fluorescence images of surfaces A and B of the banknote BN.

[0030] The light emitted by the light source 11 may be light in a wavelength band including a peak wavelength and wavelengths in the vicinity thereof. The type (wavelength) of the excitation light emitted from the light source 11 is not particularly limited, and examples thereof include ultraviolet light.

[0031] The light receiving unit 13 may receive the fluorescence emitted from the banknote BN while the light source 11 is irradiating the excitation light. In this case, the light receiving unit 13 may function as a sensor that is sensitive to at least the wavelength band of the fluorescence emitted from the banknote BN. The light receiving unit 13 outputs an electrical signal corresponding to the amount of light received as image data. More specifically, the light receiving unit 13 may include a light receiving element, which may receive light, convert it into an electrical signal corresponding to the amount of incident light, and output it as image data.

[0032] The light receiving unit 13 may receive the fluorescence emitted from the banknote BN in each of a plurality of wavelength bands and output image data for each of the plurality of wavelength bands. Specifically, as described above, at least one of R image data, G image data, and B image data may be output.

[0033] FIG. 3 is a schematic diagram illustrating an example of the configuration of the paper sheet recognition device according to the first embodiment, as viewed from an oblique direction.

[0034] Although FIG. 3 shows a case where the banknotes BN are transported in the direction of their short edges, the banknotes BN may also be transported in the direction of their long edges.

[0035] 3, the image acquisition unit 10 may be configured as an optical line sensor extending in the Y direction. In this case, the Y direction corresponds to the main scanning direction of the optical line sensor, and the X direction corresponds to the sub-scanning direction of the optical line sensor.

[0036] The light source 11 may irradiate the excitation light onto the entire banknote BN in the Y direction in a straight line that is longer than the length of the banknote BN in the Y direction. In this case, the light source 11 may include a transparent, straight, rod-shaped light guide and a light-emitting element (e.g., an LED (Light Emitting Diode)) facing at least one of both end faces of the light guide, and may irradiate the banknote BN with the excitation light via the light guide.

[0037] The light receiving unit 13 may be longer than the length of the banknote BN in the Y direction and may receive fluorescence emitted from the entire banknote BN in the Y direction. The light receiving unit 13 may also 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. That is, the light receiving unit 13 may output electrical signals corresponding to the amount of incident light in a plurality of channels (columns) corresponding to the plurality of light receiving elements (positions in the Y direction). The channels (columns) are numbers assigned to the light receiving elements in order in the Y direction. In this case, the light receiving unit 13 may output line data, which is data related to light simultaneously received in each channel, as image data. While the banknote BN is transported in the X direction (sub-scanning direction), the light source 11 repeatedly irradiates the banknote BN with excitation light and the light receiving unit 13 repeatedly receives fluorescence, thereby outputting fluorescence image data of the entire banknote BN.

[0038] In this way, the image acquisition unit 10 may acquire an image of the entire banknote BN by continuously repeating a predetermined cycle of imaging, which is one period.

[0039] The fluorescent image acquired by the image acquisition unit 10 is composed of a plurality of pixels arranged in a matrix in the Y direction (main scanning direction) and the X direction (sub-scanning direction), and the address of each pixel is specified by the channel (column) of the light receiving unit 13 corresponding to the position in the Y direction and the line (row) corresponding to the position in the X direction. The line (row) is a number assigned in order to the line data output sequentially by the light receiving unit 13.

[0040] As shown in FIG. 2, the control unit 20 includes a pre-determination processing unit 21 and a determination unit 22.

[0041] The control unit 20 is a controller that controls each part of the paper sheet recognition device 1, and is configured as a computer system that includes a CPU (Central Processing Unit), various hardware controlled by the CPU (for example, an FPGA (Field Programmable Gate Array)), etc. The control unit 20 realizes various processes by executing predetermined software programs in the CPU.

[0042] The pre-judgment processing unit 21 calculates a fluorescence level specific to the banknote BN from the fluorescence image of the banknote BN acquired by the image acquisition unit 10. Here, the fluorescence level is the average fluorescence level of the fluorescence image of the banknote BN. More specifically, it is the average brightness value of a region of the fluorescence image of the banknote BN, excluding abnormal pixels that exhibit abnormal values ​​whose brightness values ​​exceed a predetermined threshold and, if necessary, mask regions. Hereinafter, this region may be referred to as the fluorescence level calculation region. The average brightness value is calculated by dividing the sum of the brightness values ​​of all pixels included in the region by the number of pixels.

[0043] Furthermore, the pre-determination processing unit 21 may calculate a threshold value for abnormal brightness values ​​in the fluorescent image of banknote BN from the calculated fluorescent level. Hereinafter, this threshold value may be referred to as the specific threshold. More specifically, the pre-determination processing unit 21 may calculate the specific threshold value by, for example, adding a predetermined percentage (e.g., 20%) of the fluorescent level to the fluorescent level, or by adding a constant multiple (e.g., 3.8) of the standard deviation of the brightness values ​​in the entire fluorescent image of banknote BN to the fluorescent level.

[0044] Furthermore, the pre-determination processing unit 21 may set a mask area in the fluorescent image of banknote BN as described above. For example, a determination table (template information) may be prepared in advance in which the presence or absence and range of a mask area are associated with each type of banknote to be recognized, and the pre-determination processing unit 21 may set a mask area in the fluorescent image of banknote BN based on this determination table. Furthermore, the pre-determination processing unit 21 may calculate a specific threshold for a mask area by adding a threshold specific to each mask area to the fluorescence level as the threshold for determining an abnormality in the mask area.

[0045] When the image acquisition unit 10 acquires multiple images (e.g., RGB images) using light in multiple wavelength bands as fluorescence images of the banknote BN, the pre-determination processing unit 21 and the determination unit 22 may perform each process on all of the multiple images, or may perform each process on only a predetermined image among the multiple images. In the latter case, for example, a determination table may define whether or not each process by the pre-determination processing unit 21 and the determination unit 22 is to be performed for each type of banknote to be recognized, and the pre-determination processing unit 21 and the determination unit 22 may select an image to be processed based on the determination table.

[0046] As shown in FIG. 2, the determination unit 22 includes an abnormal area extraction unit 23 and a cut-and-paste note determination unit 24.

[0047] The abnormal region extraction unit 23 extracts an abnormal region from the fluorescent image of the banknote BN based on the fluorescent light level calculated by the pre-determination processing unit 21.

[0048] In this case, the abnormal region extraction unit 23 may extract, as an abnormal region, a pixel region in the fluorescent image of the banknote BN that exceeds the specific threshold value, thereby making it possible to more appropriately extract an abnormal region in the fluorescent image of the banknote to be recognized.

[0049] Fig. 4 is a schematic diagram for explaining the process of extracting an abnormal area by scanning a fluorescent image of a banknote in the main scanning direction in embodiment 1. Fig. 5 is a schematic diagram for explaining the process of extracting an abnormal area by scanning a fluorescent image of a banknote in the sub-scanning direction in embodiment 1. Fig. 6 is a schematic diagram for explaining the process of extracting an abnormal area by scanning a fluorescent image of a banknote in an oblique direction (+45°) in embodiment 1. Fig. 7 is a schematic diagram for explaining the process of extracting an abnormal area by scanning a fluorescent image of a banknote in an oblique direction (-45°) in embodiment 1.

[0050] The abnormal region extraction unit 23 may extract abnormal regions by scanning the fluorescent image of the banknote in at least one of the main scanning direction, sub-scanning direction, and diagonal direction (a direction forming a predetermined angle with respect to the main scanning direction and sub-scanning direction), or may extract abnormal regions by scanning the fluorescent image of the banknote in each of the main scanning direction, sub-scanning direction, and diagonal direction. This makes it possible to more appropriately extract abnormal regions in the fluorescent image of the banknote to be recognized.

[0051] More specifically, as shown in FIGS. 4 to 7 , the abnormal region extraction unit 23 may extract an abnormal region for each determination region 40 by shifting the determination region 40 by a predetermined number of pixels (e.g., one pixel at a time) in at least one of the main scanning direction, the sub-scanning direction, and the diagonal direction. The shape of the determination region 40 may be set as appropriate, for example, rectangular. In this case, the length of the rectangle in the longitudinal direction may be large enough to encompass at least both ends of the fluorescent image IMG of the banknote BN, and the width of the rectangle in the lateral direction may be a predetermined length (e.g., approximately 10 mm) shorter than the length of the fluorescent image IMG of the banknote BN in the lateral direction (bill width). Note that when shifting the determination region 40 by a predetermined number of pixels in the diagonal direction, the determination region 40 may be shifted by a predetermined number of pixels (e.g., one pixel at a time) in both the main scanning direction Y and the sub-scanning direction X.

[0052] The predetermined angle that the diagonal direction forms with the main scanning direction and the sub-scanning direction can be set appropriately, and may be, for example, 45° as shown in Figures 6 and 7. The diagonal direction may also be two diagonal directions including a direction that forms a positive angle with the main scanning direction and the sub-scanning direction (for example, +45°, see Figure 6) and a direction that forms a negative angle with the main scanning direction and the sub-scanning direction (for example, -45°, see Figure 7), and the abnormal area extraction unit 23 may scan in each of the diagonal directions.

[0053] The cut-and-pasted note determination unit 24 identifies (determines) whether or not the banknote BN is a pasted note based on the abnormal area extracted by the abnormal area extraction unit 23.

[0054] The cut-and-paste note determination unit 24 may calculate an evaluation value based on the extracted abnormal region and compare the calculated evaluation value with a predetermined threshold to determine whether or not banknote BN is a laminated note. That is, if the calculated evaluation value exceeds the threshold, the cut-and-paste note determination unit 24 may determine that banknote BN is a laminated note, and if the calculated evaluation value does not exceed the threshold, the cut-and-paste note determination unit 24 may determine that banknote BN is not a laminated note. Examples of evaluation values ​​include the proportion of pixels in the abnormal region (abnormal pixel rate) in the entire fluorescence level calculation region or in a predetermined determination region (partial region), and the average value of the differences between the luminance value of each pixel in the abnormal region and the specific threshold (average value of the sum of differences). A combination of these values, for example, a value obtained by multiplying them together, may also be used as the evaluation value.

[0055] The cut-and-pasted note determination unit 24 may also determine whether or not banknote BN is a stuck note for each predetermined determination area (partial area). If the determination result for at least one determination area is that banknote BN is a stuck note, the banknote BN may be determined to be a stuck note.

[0056] Next, the operation of the paper sheet recognition apparatus 1 according to this embodiment will be described with reference to Fig. 8. Fig. 8 is a flowchart illustrating an example of the operation of the paper sheet recognition apparatus according to the first embodiment.

[0057] As shown in FIG. 8, first, the image acquisition unit 10 acquires a fluorescent image of the banknote BN by irradiating the banknote BN with excitation light and receiving fluorescent light emitted from the banknote BN (step S11).

[0058] Next, the pre-judgment processing unit 21 calculates the fluorescence level specific to the banknote BN from the fluorescence image acquired by the image acquisition unit 10 (step S12).

[0059] Next, the abnormal region extracting unit 23 extracts an abnormal region from the fluorescent image based on the fluorescent light level calculated by the pre-determination processing unit 21 (step S13).

[0060] Thereafter, the cut-and-pasted note determination unit 24 determines whether or not the banknote BN is a pasted note based on the abnormal area extracted by the abnormal area extraction unit 23 (step S14), and the operation of the paper sheet recognition device 1 ends.

[0061] According to this embodiment, an abnormal area is extracted from the fluorescent image of the banknote BN based on the fluorescence level specific to the banknote BN (the fluorescence level of each individual banknote BN), and whether or not the banknote BN is a laminated note is identified based on the extracted abnormal area. Therefore, even if the fluorescence level of banknotes varies depending on the medium, it is possible to appropriately extract an abnormal area from the fluorescent image of the banknote that is the subject of identification, and as a result, it is possible to determine with high accuracy whether or not the banknote is a laminated note based on the appropriately extracted fluorescent abnormal area.

[0062] (Embodiment 2) The configuration of the paper sheet processing apparatus according to this embodiment will be described with reference to Fig. 9 and Fig. 10. Fig. 9 is a schematic perspective view showing the appearance of an example of a paper sheet processing apparatus according to embodiment 2. Fig. 10 is a block diagram illustrating an example of the configuration of the paper sheet processing apparatus according to embodiment 2.

[0063] The sheet processing apparatus according to this embodiment may have, for example, the configuration shown in Fig. 9. The sheet processing apparatus 300 shown in Fig. 9 incorporates a sheet recognition device (see Fig. 10) that performs a banknote recognition process, and includes a hopper 301 on which a plurality of banknotes to be processed are placed in a stacked state, two reject units 302 from which rejected banknotes are discharged, an operation unit 303 for inputting instructions from an operator, four stacking units 306a to 306d for sorting and stacking banknotes that have been recognized as to their denomination, authenticity, and fitness within a housing 304, and a display unit 305 for displaying information such as the results of recognition and counting of banknotes and the stacking status of each of the stacking units 306a to 306d.

[0064] As shown in FIG. 10, the sheet processing apparatus 300 further includes a transport unit 310, a main body storage unit 330, and a main body control unit 320.

[0065] The transport unit 310 is configured to include transport rollers for transporting banknotes, a drive mechanism (drive source and drive force transmission mechanism) for driving the transport rollers, and the like.

[0066] The main body storage unit 330 is composed of a storage device such as a semiconductor memory (RAM or ROM) and a hard disk, and stores various programs and information (data) for controlling the sheet processing apparatus 300.

[0067] The main body control unit 320 is a controller that controls each unit of the sheet processing apparatus 300, and is configured as a computer system including a CPU, various hardware (e.g., FPGA) controlled by the CPU, etc. The main body control unit 320 realizes various processes by executing, on the CPU, predetermined software programs stored in the main body storage unit 330 (which may be a storage unit provided separately from the main body storage unit 330).

[0068] FIG. 11 is a block diagram illustrating an example of the configuration of a paper sheet recognition device according to the second embodiment.

[0069] As shown in FIG. 11, the paper sheet recognition device 200 according to this embodiment includes a detection unit 210, a control unit 220, and a storage unit 230.

[0070] The detection unit 210 detects various characteristics of the banknotes being transported, and may be provided with a magnetic detection unit 211 and a thickness detection unit 212 along the banknote transport path in addition to the image acquisition unit 10. The image acquisition unit 10 acquires and outputs fluorescent images of the banknotes (image data obtained by fluorescence) as described above.

[0071] The storage unit 230 is configured with a storage device such as a semiconductor memory (RAM or ROM) or a hard disk, and stores various programs and information (data) for controlling the paper sheet recognition device 200.

[0072] The control unit 220 is a controller that controls each unit of the paper sheet recognition device 200, and is configured as a computer system including a CPU, various hardware (e.g., FPGA) controlled by the CPU, etc. The control unit 220 realizes various processes by executing predetermined software programs stored in the storage unit 230 in the CPU.

[0073] The control unit 220 also performs an identification process using various signals related to the banknotes acquired from the detection unit 210. The control unit 220 identifies the denomination and authenticity of the banknotes. Furthermore, the control unit 220 determines whether the banknotes are fit or unfit. More specifically, the control unit 220 detects dirt, folds, tears, etc. on the banknotes, and also detects tape, etc. attached to the banknotes from the thickness of the banknotes, to determine whether the banknotes should be treated as fit notes that can be reused in the market or unfit notes that are not suitable for market circulation.

[0074] At this time, the control unit 220 uses the image (image data) of the banknote acquired by the image acquisition unit 10 to identify the denomination, authenticity, fitness, etc. The control unit 220 also performs a fluorescence abnormality determination process, which will be described later, as a determination process regarding the authenticity and fitness of the banknote.

[0075] Next, the configuration of the image acquisition unit 10 will be described with reference to Fig. 12. Fig. 12 is a cross-sectional view illustrating an example of the configuration of the image acquisition unit included in the paper sheet recognition device according to the second embodiment.

[0076] As shown in FIG. 12 , the image acquisition unit 10 includes sensor units 110 and 120 arranged opposite each other. The sensor units 110 and 120 are each composed of a contact image sensor facing the transport path of the paper sheet processing apparatus according to this embodiment. A gap is formed between the sensor units 110 and 120, which are spaced apart in the Z direction, allowing banknotes BN to be transported in the X direction within the XY plane. This gap forms part of the transport path of the paper sheet processing apparatus according to this embodiment. The sensor units 110 and 120 are located above (+Z direction) and below (-Z direction) the transport path, respectively. The Y direction corresponds to the main scanning direction of the sensor units 110 and 120, and the X direction corresponds to the sub-scanning direction of the sensor units 110 and 120.

[0077] 12, each of the sensor units 110 and 120 includes two light sources 111b for reflection and excitation, a condenser lens 112, a light receiving unit 113, and a substrate 114. Each of the sensor units 110 and 120 also includes a case for housing these components, and a cover glass fitted into the opening of the case on the transport path side.

[0078] The light source 111b for reflection and excitation includes, for example, a light guide extending in the main scanning direction and multiple types of light-emitting elements facing at least one end face of the light guide and emitting light of multiple wavelengths. The light source 111b of the sensor unit 110 and the light source 111b of the sensor unit 120 sequentially irradiate the A and B sides of the banknote BN with light of multiple wavelengths, including excitation light. The light source 111b irradiates light of multiple wavelengths, for example, light with different peak wavelengths. Specifically, the light source 111b sequentially irradiates infrared light (IR, or multiple types of infrared light with different peak wavelengths), white light (W) including red light (R), green light (G), and blue light (B), and ultraviolet light (UV) as excitation light.

[0079] The condenser lens 112 is composed of, for example, a rod lens array in which multiple rod lenses are arranged in the main scanning direction, and condenses light emitted from the light source 111b and reflected by side A or B of the banknote BN, and fluorescent light emitted from side A or B of the banknote BN.

[0080] 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, and each light receiving element is sensitive to the wavelength band of the light of multiple wavelengths emitted by the light source 111b and the wavelength band of the fluorescence emitted from the banknote BN.

[0081] Each light receiving element may be, for example, a photodetector having sensitivity at least from the visible region to the infrared region of wavelength 1100 nm, such as a silicon (Si) photodiode. Each light receiving element is mounted on substrate 114, receives light collected by collecting lens 112, converts it into an electrical signal corresponding to the amount of incident light, and outputs it to substrate 114. Each light receiving element receives light or fluorescence of each wavelength in accordance with the timing of irradiation of light of that wavelength by light source 111b.

[0082] 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 signals of the light receiving unit 113 (each light receiving element), A / D converts them to digital data, and outputs them as image data.

[0083] The sensor unit 120 further includes one light source 111a for transmission.

[0084] The light source 111a is disposed on the optical axis of the condenser lens 112 of the sensor unit 110, and a portion of the light emitted from the light source 111a passes through the banknote BN, is condensed by the condenser lens 112 of the sensor unit 110, and is detected by the light receiving unit 113. The light source 111a sequentially or simultaneously irradiates side B of the banknote BN with light of different wavelength bands. The light source 111a irradiates light of multiple wavelengths, for example, light with different peak wavelengths. Specifically, the light source 111a irradiates infrared light (IR) and green light (G).

[0085] It should be noted that "multiple wavelengths of light" refers to light having different wavelength bands, and may have different peak wavelengths. For example, for visible light, multiple wavelengths of light may be light having different colors, and for infrared and ultraviolet light, light whose wavelength bands only partially overlap or whose wavelength bands do not overlap.

[0086] Each light source 111b may include an LED element that emits infrared light (IR) having a peak wavelength of 750 nm or more, an LED element that emits red light (R) having a peak wavelength of 600 nm or more and less than 750 nm, an LED element that emits green light (G) having a peak wavelength of 500 nm or more and less than 600 nm, an LED element that emits blue light (B) having a peak wavelength of 400 nm or more and less than 500 nm, and an LED element that has a peak wavelength in the wavelength band of the excitation light.

[0087] Light source 111a may include an LED element that emits green light having a peak wavelength of 500 nm or more and less than 600 nm, and an LED element that emits infrared light having a peak wavelength of 750 nm or more.

[0088] FIG. 13 is a schematic perspective view illustrating an example of the configuration of a light receiving unit included in the image acquisition unit of the second embodiment.

[0089] As shown in FIG. 13, each light receiving section 113 has a plurality of pixels 131GP arranged in a row in the main scanning direction, and each pixel 131GP has one first light receiving element (image sensor) 131B, one second light receiving element (image sensor) 131G, and one third light receiving element (image sensor) 131R, and the first light receiving element 131B, the second light receiving element 131G, and the third light receiving element 131R are arranged in a row in the main scanning direction in this order.

[0090] The first light receiving element 131B is a blue light receiving element including a photodetector 1310 and a blue color resist (color filter) 1311B that transmits infrared light and blue light and absorbs red light and green light. The second light receiving element 131G is a green light receiving element including a photodetector 1310 and a green color resist (color filter) 1311G that transmits infrared light and green light and absorbs red light and blue light. The third light receiving element 131R is a red light receiving element including a photodetector 1310 and a red color resist (color filter) 1311R that transmits infrared light and red light and absorbs green light and blue light.

[0091] Here, the light receiving element (image capturing element) means an element that detects the intensity of light in a predetermined wavelength band (converts it into an electrical signal), and may be configured to include a photodetector such as a photodiode, and a color resist that is provided on the light receiving surface of the photodetector and suppresses the transmission of light in wavelength bands (e.g., green and red) excluding the predetermined wavelength band to be detected (e.g., blue and infrared wavelength bands).

[0092] FIG. 14 is a schematic diagram showing wavelength characteristics of the color resist of the light receiving unit included in the image acquisition unit of the second embodiment.

[0093] As shown in Figure 14, blue color resist (color filter) 1311B mainly transmits blue light and infrared light (see dashed line), green color resist (color filter) 1311G mainly transmits green light and infrared light (see dashed line), and red color resist (color filter) 1311R mainly transmits red light and infrared light (see dashed line). Therefore, the first light receiving element 131B, the second light receiving element 131G, and the third light receiving element 131R can selectively receive blue light (approximately wavelength 400 nm to 500 nm), green light (approximately wavelength 500 nm to 600 nm), and red light (approximately wavelength 600 nm to 700 nm), respectively, and the first light receiving element 131B, the second light receiving element 131G, and the third light receiving element 131R can all receive infrared light (approximately wavelength 800 nm to 1000 nm).

[0094] However, since each color resist can usually transmit light of colors other than the corresponding color to a certain extent, the first light receiving element 131B, the second light receiving element 131G, and the third light receiving element 131R may receive light of colors other than the corresponding color to a certain extent.

[0095] Each sensor unit 110, 120 repeatedly captures images of the banknote BN being transported in the transport direction and outputs the image data, allowing the image acquisition unit 10 to acquire images (two-dimensional images) of the entire surfaces of the banknote BN. Specifically, the image acquisition unit 10 acquires a transmission image, a reflection image and a fluorescence image of side A of the banknote BN based on the output signal of the sensor unit 110, and acquires a reflection image and a fluorescence image of side B of the banknote BN based on the output signal of the sensor unit 120. At this time, a color image corresponding to irradiation with visible light, i.e., an RGB image, is acquired as the reflection image. Also, a color image of fluorescence emitted from the banknote BN in response to irradiation with excitation light, i.e., an RGB image, is acquired as the fluorescence image.

[0096] Next, referring back to FIG. 11, the control unit 220 will be further described.

[0097] The control unit 220 includes a pre-determination processing unit 221 and a determination unit 222 .

[0098] The control unit 220 performs the following processes on the necessary images among the RGB images obtained by fluorescence, based on a determination table stored in advance in the storage unit 230. The determination table defines whether or not to perform each of the following processes for each type of banknote to be recognized.

[0099] The pre-determination processing unit 221 performs (1) image resolution conversion, (2) rotation correction, (3) mask area setting, (4) fluorescence level calculation, (5) specific threshold calculation, and (6) specific threshold calculation for the mask area.

[0100] Fig. 15 is a schematic diagram showing an example of a fluorescent image of a banknote before rotation correction by the pre-determination processing unit in embodiment 2. Fig. 16 is a schematic diagram showing an example of a fluorescent image of a banknote after rotation correction by the pre-determination processing unit in embodiment 2.

[0101] (1) In image resolution conversion, the pre-determination processing unit 221 reduces the resolution of the fluorescence image of banknote BN acquired by the image acquisition unit 10. Specifically, for example, an original image of 200 × 100 dpi or 200 × 33 dpi is converted into an image of 33 × 33 dpi or 16.5 × 16.5 dpi. At this time, when converting from 6 pixels × 3 pixels or 6 pixels to 1 pixel, or from 12 pixels × 6 pixels or 12 pixels × 2 pixels to 1 pixel, the maximum value within the pre-conversion region may be used as the pixel value after conversion in order to retain the fluorescence abnormality feature.

[0102] (2) In rotation correction, as shown in FIGS. 15 and 16, the pre-determination processing unit 221 corrects the tilt of the fluorescent image IMG of banknote BN.

[0103] (3) In mask area setting, as shown in Fig. 16, the pre-determination processing unit 221 sets a mask area 241 in the fluorescent image IMG of banknote BN based on the determination table. For this reason, the determination table specifies whether or not a mask area is present (or the range of the mask area if it is necessary to set one) for each type of banknote to be recognized. The mask area is set to an area that includes a fluorescent reaction portion, which is a portion of the banknote that exhibits a fluorescent reaction, such as a thread.

[0104] (4) In the fluorescence level calculation, the pre-judgment processing unit 221 calculates the fluorescence level specific to the banknote BN, i.e., the average fluorescence level of the fluorescence image of the banknote BN, from the fluorescence image of the banknote BN acquired by the image acquisition unit 10. More specifically, as in the first embodiment, the pre-judgment processing unit 221 calculates the average brightness value of the fluorescence level calculation region of the fluorescence image of the banknote BN, i.e., the region excluding the abnormal pixels and the mask region 241.

[0105] (5) In calculating the specific threshold, the pre-determination processing unit 221 calculates the specific threshold from the fluorescence level, as in the first embodiment.

[0106] (6) In the calculation of the specific threshold value for the mask region, the pre-determination processing unit 221 calculates the specific threshold value for the mask region from the fluorescence level, as in the first embodiment.

[0107] As shown in FIG. 11, the determination unit 222 has a fluorescence abnormality determination unit 225 , a mask region determination unit 226 , an abnormal region extraction unit 223 , and a cut-and-paste determination unit 224 .

[0108] FIG. 17 is a schematic diagram for explaining the process of determining fluorescence abnormalities in the entire banknote by the fluorescence abnormality determination unit in the second embodiment.

[0109] 17, the fluorescence abnormality determination unit 225 determines whether or not the entire banknote BN has a fluorescence abnormality by comparing the fluorescence level calculated by the determination pre-processing unit 221 (the average brightness value of the fluorescence level calculation area 242 excluding the abnormal pixels (not shown) and the mask area 241) with a predetermined threshold. That is, if the fluorescence level exceeds the threshold, the fluorescence abnormality determination unit 225 determines that the fluorescence characteristics of the entire banknote BN are abnormal, and if the fluorescence level does not exceed the threshold, it determines that the fluorescence characteristics of the entire banknote BN are normal.

[0110] FIG. 18 is a schematic diagram showing an example of a fluorescent image of a banknote determined to have a fluorescent abnormality throughout the entire banknote in the second embodiment.

[0111] If the fluorescence characteristics of the entire banknote BN are abnormal, the brightness value of the entire fluorescence image IMG of the banknote BN will be large, as shown in FIG.

[0112] FIG. 19 is a schematic diagram for explaining the process of determining whether there is a fluorescence abnormality in a mask region by the mask region determining unit in the second embodiment.

[0113] 19, the mask area determination unit 226 determines whether or not there is a fluorescence abnormality in the mask area 241 by comparing the evaluation value of the mask area 241, specifically the average brightness value, with the mask area-specific threshold value. For example, if the average brightness value of the mask area 241 exceeds the mask area-specific threshold value, the mask area determination unit 226 determines that the fluorescence reaction portion of the mask area 241 is normal, and if the average brightness value of the mask area 241 does not exceed the mask area-specific threshold value, the mask area determination unit 226 determines that the fluorescence reaction portion of the mask area 241 is abnormal. In the latter case, the mask area determination unit 226 determines that banknote BN is a counterfeit note.

[0114] FIG. 20 is a schematic diagram showing an example of a fluorescent image of a banknote in which the mask area is determined to have a fluorescent abnormality in the second embodiment.

[0115] An example of a case where the fluorescence reaction portion of the mask area 241 is abnormal is when no fluorescence is detected in the mask area 241, as shown in FIG.

[0116] Fig. 21 is a schematic diagram illustrating the process of extracting an abnormal area by scanning a fluorescent image of a banknote in the main scanning direction in embodiment 2. Fig. 22 is a schematic diagram illustrating the process of extracting an abnormal area by scanning a fluorescent image of a banknote in the sub-scanning direction in embodiment 2. Fig. 23 is a schematic diagram illustrating the process of extracting an abnormal area by scanning a fluorescent image of a banknote in an oblique direction (+45°) in embodiment 2. Fig. 24 is a schematic diagram illustrating the process of extracting an abnormal area by scanning a fluorescent image of a banknote in an oblique direction (-45°) in embodiment 2.

[0117] The abnormal region extraction unit 223 extracts an abnormal region in the fluorescent image of the banknote BN based on the specific threshold calculated from the fluorescent light level. At this time, the abnormal region extraction unit 223 extracts a pixel region in the fluorescent image of the banknote BN that exceeds the specific threshold as an abnormal region.

[0118] 21 to 24, the abnormal region extraction unit 223 extracts an abnormal region 243 for each rectangular determination region 240 while shifting the determination region 240 by a predetermined number of pixels (for example, by one pixel) in each of the main scanning direction, sub-scanning direction, and diagonal directions (+45° and -45°). The longitudinal length of the determination region 240 is large enough to encompass at least both ends of the fluorescent image IMG of the banknote BN, and the lateral width of the determination region 240 is, for example, 10 pixels (approximately 10 mm). When shifting the determination region 240 by a predetermined number of pixels in the diagonal direction, the determination region 240 is shifted by a predetermined number of pixels (for example, by one pixel) in both the main scanning direction Y and the sub-scanning direction X.

[0119] The cut-and-paste determination unit 224 calculates an evaluation value for each determination area 240 at each position based on the abnormal area 243 extracted by the abnormal area extraction unit 223, and compares the calculated evaluation value with a predetermined threshold to determine whether the fluorescence characteristics of the determination area 240 are normal. That is, if the calculated evaluation value exceeds the threshold, the cut-and-paste determination unit 224 determines that the fluorescence characteristics of the determination area 240 are abnormal, and if the calculated evaluation value does not exceed the threshold, it determines that the fluorescence characteristics of the determination area 240 are normal.

[0120] Here, the cut and pasted note determination unit 224 uses (1) the abnormal pixel rate A, (2) the average value B of the difference sum values, and (3) the product C of the abnormal pixel rate A and the average value B of the difference sum values ​​as evaluation values.

[0121] (1) The abnormal pixel rate A is the ratio of pixels in the abnormal region 243 to the judgment region 240.

[0122] (2) The average value B of the difference sum is the average value of the difference between the brightness value of each pixel in the abnormal region 243 and the specific threshold value.

[0123] (3) The product C is the average value in the determination region 240 of the difference between the luminance value of each pixel in the abnormal region 243 and the specific threshold value.

[0124] Furthermore, the cut-and-paste note determination unit 224 determines whether the fluorescence characteristics of the determination region 240 are normal by comparing each of the evaluation values ​​(1) to (3) with a predetermined threshold (prepared in advance for each evaluation value). That is, if the calculated abnormal pixel rate A exceeds a predetermined threshold, the cut-and-paste note determination unit 224 determines that the fluorescence characteristics of the determination region 240 are abnormal; if the calculated abnormal pixel rate A does not exceed this threshold, the cut-and-paste note determination unit 224 determines that the fluorescence characteristics of the determination region 240 are normal. If the calculated average value B exceeds a predetermined threshold, the cut-and-paste note determination unit 224 determines that the fluorescence characteristics of the determination region 240 are abnormal; if the calculated average value B does not exceed this threshold, the cut-and-paste note determination unit 224 determines that the fluorescence characteristics of the determination region 240 are normal. Furthermore, if the calculated product C exceeds a predetermined threshold, the cut-and-paste note determination unit 224 determines that the fluorescence characteristics of the determination region 240 are abnormal; if the calculated product C does not exceed this threshold, the cut-and-paste note determination unit 224 determines that the fluorescence characteristics of the determination region 240 are normal.

[0125] If the cut-and-paste note determination unit 224 determines that the fluorescence characteristics of at least one of the determination areas 240 are abnormal based on at least one of the evaluation values ​​(1) to (3) above, the determination unit 222 determines that banknote BN is a laminated note. On the other hand, if the cut-and-paste note determination unit 224 determines that the fluorescence characteristics of the determination areas 240 are normal based on any of the evaluation values ​​(1) to (3) above, the determination unit 222 determines that banknote BN is not a laminated note.

[0126] In addition, the cut-and-paste ticket judgment unit 224 may not judge whether the fluorescent characteristics of the judgment area 240 are normal or abnormal (OR judgment) based on each of the evaluation values ​​(1) to (3) above as described above, but may judge (AND judgment) that the fluorescent characteristics of the judgment area 240 are abnormal only if all of the evaluation values ​​(1) to (3) above exceed the corresponding threshold values.

[0127] FIG. 25 is a schematic diagram showing an example of a fluorescent image of a banknote determined to have a fluorescent abnormality by scanning in the main scanning direction in the second embodiment.

[0128] By scanning in the main scanning direction, for example, as shown in FIG. 25, it is possible to detect the fluorescent light emitted by an adhesive or the like attached to a joint AA extending in the short direction of a banknote.

[0129] FIG. 26 is a schematic diagram showing an example of a fluorescent image of a banknote determined to have a fluorescent abnormality by scanning in the sub-scanning direction in the second embodiment.

[0130] By scanning in the sub-scanning direction, for example, as shown in FIG. 26, it is possible to detect the fluorescent light emitted by an adhesive or the like attached to a joint AA extending in the longitudinal direction of a banknote.

[0131] FIG. 27 is a schematic diagram showing an example of a fluorescent image of a banknote determined to have a fluorescent abnormality by scanning in an oblique direction (+45°) in the second embodiment.

[0132] By scanning in an oblique direction (+45°), for example, as shown in FIG. 27, it is possible to detect the fluorescent light emitted by an adhesive or the like attached to a joint AA extending in an oblique direction (+45°) of a banknote.

[0133] FIG. 28 is a schematic diagram showing an example of a fluorescent image of a banknote determined to have a fluorescent abnormality by scanning in an oblique direction (−45°) in the second embodiment.

[0134] By scanning in an oblique direction (-45°), for example, as shown in FIG. 28, it is possible to detect the fluorescent light emitted from a tape or the like attached to a joint AA extending in an oblique direction (-45°) of a banknote.

[0135] Next, the operation related to fluorescence abnormality determination of the paper sheet recognition apparatus 200 according to this embodiment will be described with reference to Fig. 29 and Fig. 30. Fig. 29 is the first half of a flowchart illustrating an example of fluorescence abnormality determination processing of the paper sheet recognition apparatus according to embodiment 2. Fig. 30 is the second half of the flowchart shown in Fig. 29.

[0136] As shown in FIG. 29, first, the image acquisition unit 10 acquires fluorescent images (RGB images) of both sides of the banknote BN by irradiating the banknote BN with excitation light and receiving fluorescent light emitted from the banknote BN (step S21).

[0137] Next, the pre-judgment processing unit 221 performs (1) image resolution conversion, (2) rotation correction, (3) mask area setting, (4) fluorescence level calculation, (5) specific threshold calculation, and (6) specific threshold calculation for the mask area in this order (step S22).

[0138] The processes from step S22 onwards are carried out on the necessary images out of the fluorescent images (RGB images) of both sides of the banknote BN, based on a determination table stored in advance in the storage unit 230.

[0139] Next, the fluorescence abnormality judgment unit 225 compares the fluorescence level calculated by the judgment pre-processing unit 221 with a predetermined threshold value (step S23), and if the fluorescence level exceeds the threshold value (step S23: No), it judges that the fluorescence characteristics of the entire banknote BN are abnormal, and the fluorescence abnormality judgment process of the paper sheet recognition device 200 ends.

[0140] If the fluorescence level does not exceed the threshold (step S23: Yes), the mask area determination unit 226 compares the evaluation value (average brightness value) of the mask area with the specific threshold value for the mask area (step S24), and if the average brightness value of the mask area exceeds the specific threshold value for the mask area (step S24: Yes), it determines that the fluorescence reaction part of the mask area is normal, and if the average brightness value of the mask area does not exceed the specific threshold value for the mask area (step S24: No), it determines that the fluorescence reaction part of the mask area is abnormal.

[0141] Here, step S24 is executed for all the mask areas that have been set.

[0142] Regardless of the result of the determination in step S24, the abnormal region extraction unit 223 extracts an abnormal region 243 for each determination region 240 at each position while shifting the rectangular determination region 240 in the main scanning direction, for example, by one pixel at a time, and the cut-and-paste note determination unit 224 calculates the evaluation values ​​(1) to (3) above for each determination region 240 at each position based on the abnormal region 243 extracted by the abnormal region extraction unit 223, and compares each calculated evaluation value with a predetermined threshold (prepared for each evaluation value) (step S25). If at least one evaluation value exceeds the corresponding threshold, the cut-and-paste note determination unit 224 determines that the fluorescence characteristic of the determination region 240 is abnormal (step S25: No). If all evaluation values ​​do not exceed the corresponding threshold, the cut-and-paste note determination unit 224 determines that the fluorescence characteristic of the determination region 240 is normal (step S25: Yes).

[0143] Regardless of the judgment result of step S25, as shown in FIG. 30, the abnormal area extraction unit 223 then shifts the rectangular judgment area 240, for example by one pixel at a time, to extract an abnormal area 243 for each judgment area 240 at each position, and the cut-and-paste judgment unit 224 calculates the evaluation values ​​(1) to (3) above for each judgment area 240 at each position based on the abnormal area 243 extracted by the abnormal area extraction unit 223, and compares each calculated evaluation value with a predetermined threshold (prepared in advance for each evaluation value) (step S26).If at least one evaluation value exceeds the corresponding threshold, it judges that the fluorescence characteristics of the judgment area 240 are abnormal (step S26: No), and if all evaluation values ​​do not exceed the corresponding threshold, it judges that the fluorescence characteristics of the judgment area 240 are normal (step S26: Yes).

[0144] Regardless of the judgment result of step S26, the abnormal area extraction unit 223 then extracts an abnormal area 243 for each judgment area 240 at each position while shifting the rectangular judgment area 240 diagonally (+45°), for example, by one pixel at a time, and the cut-and-paste judgment unit 224 calculates the evaluation values ​​(1) to (3) above for each judgment area 240 at each position based on the abnormal area 243 extracted by the abnormal area extraction unit 223, and compares each calculated evaluation value with a predetermined threshold (prepared in advance for each evaluation value) (step S27).If at least one evaluation value exceeds the corresponding threshold, it judges that the fluorescence characteristics of the judgment area 240 are abnormal (step S27: No), and if all evaluation values ​​do not exceed the corresponding threshold, it judges that the fluorescence characteristics of the judgment area 240 are normal (step S27: Yes).

[0145] Regardless of the judgment result of step S27, the abnormal area extraction unit 223 then extracts an abnormal area 243 for each judgment area 240 at each position while shifting the rectangular judgment area 240 diagonally (-45°), for example, by one pixel at a time, and the cut-and-paste judgment unit 224 calculates the evaluation values ​​(1) to (3) above for each judgment area 240 at each position based on the abnormal area 243 extracted by the abnormal area extraction unit 223, and compares each calculated evaluation value with a predetermined threshold (prepared in advance for each evaluation value) (step S28).If at least one evaluation value exceeds the corresponding threshold, it judges that the fluorescence characteristics of the judgment area 240 are abnormal (step S28: No), and if all evaluation values ​​do not exceed the corresponding threshold, it judges that the fluorescence characteristics of the judgment area 240 are normal (step S28: Yes).

[0146] The order of steps S25 to S28 is not particularly limited and may be changed as appropriate.

[0147] The determination unit 222 determines that the banknote is an abnormal fluorescence note if at least one of the determination results in steps S25 to S28 is abnormal, and determines that the banknote is a normal fluorescence note if all of the determination results in steps S25 to S28 are normal. Furthermore, the determination unit 222 determines that the banknote is an abnormal banknote if at least one of the determination results in steps S25 to S28 is abnormal, and determines that the banknote is not a laminated banknote if all of the determination results in steps S25 to S28 are normal.

[0148] According to this embodiment, similarly to the first embodiment, it is possible to determine with high accuracy whether or not a bonded ticket is present based on an appropriately extracted fluorescence abnormality region.

[0149] (Embodiment 3) First, an outline of the paper sheet recognition device according to this embodiment will be described.

[0150] Foreign objects such as transparent tape, mending tape, and adhesives attached to paper sheets are transparent and cannot be detected from images acquired by a contact image sensor (hereinafter abbreviated as CIS). In other words, until now, no CIS was known that could simultaneously detect these foreign objects.

[0151] Therefore, in this embodiment, a common characteristic of chemical substances is utilized to detect these foreign substances with a single sensor. Specifically, transparent tape, mending tape, and adhesives contain organic adhesive or adhesive substances that, when excited by irradiation with light of a specific wavelength, emit fluorescence at a different wavelength. Although it is known that this excitation wavelength varies depending on the type of organic compound, the inventors' research has revealed that, if the irradiation wavelength is 300 to 350 nm, most foreign substances emit strong fluorescence at wavelengths of 400 to 500 nm, and under these conditions, many foreign substances can be detected.

[0152] Additionally, LEDs are often used as the light source for CIS because of their advantages of being inexpensive, compact, low power, and low heat generation. However, the half-width of the emitted wavelength of LEDs is narrow, and one type of LED cannot cover the entire wavelength band of 300 to 350 nm.

[0153] Therefore, LEDs with multiple wavelengths required to fluoresce these foreign objects are simultaneously turned on and irradiated onto the paper sheet through an excitation light source filter. This causes these foreign objects to simultaneously emit fluorescence, which can then be detected by a light-receiving sensor through a light-receiving filter. Furthermore, by hybridizing this light-receiving sensor with an existing CIS for identification, additional functions can be added to the paper sheet identification device. Furthermore, by using an RGB color filter in the light-receiving sensor, it becomes easier to distinguish between foreign objects and fluorescent ink based on the difference in emitted color. It is also known that fingerprints fluoresce weakly overall. The algorithm for distinguishing between foreign objects and fingerprints checks the shape and intensity of the blue fluorescent area, and if it is linear or locally distributed, it is determined to be a foreign object.

[0154] Fig. 31 is a schematic diagram showing an example of a color image obtained by irradiating visible light onto a banknote with adhesive in embodiment 3. Fig. 32 is a schematic diagram of a color image obtained by irradiating excitation light of a specific wavelength onto the banknote shown in Fig. 31.

[0155] As shown in Figure 31, when a banknote with adhesive is irradiated with multiple lights of specific wavelengths, not only does the adhesive fluoresce blue (see the white area in Figure 32), but the transparent tape and mending tape also fluoresce blue. By reading these emitted lights with a contact image sensor, an image of the foreign matter can be obtained, and the presence or absence of the foreign matter can be determined from this image. Furthermore, by extracting only the blue component from the obtained image and performing an evaluation, it becomes easy to separate the foreign matter that fluoresces blue from the fluorescent ink that emits red, yellow, and / or green light.

[0156] The configuration of the image acquisition sensor unit included in the paper sheet recognition apparatus according to the present embodiment will be described with reference to Fig. 33. Fig. 33 is a cross-sectional schematic view illustrating an example of the configuration of the image acquisition sensor unit included in the paper sheet recognition apparatus according to the third embodiment.

[0157] As shown in Figure 33, the image acquisition sensor unit 400 provided in the paper sheet recognition device of this embodiment is composed of a contact image sensor facing the conveying path of the paper sheet processing device, and the Y direction corresponds to the main scanning direction of the sensor unit 400, and the X direction corresponds to the sub-scanning direction of the sensor unit 400.

[0158] 33, similar to each of the sensor units 110 and 120 described in the second embodiment, the sensor unit 400 includes two reflection light sources 411b, a condenser lens 412, a light receiving unit 413, a substrate 414, a case 415 that houses these components, and a cover glass 416 fitted into the opening of the case 415 on the conveyance path side. However, in this embodiment, each light source 411b does not emit excitation light, and the sensor unit 400 additionally includes an excitation light source 411c that emits excitation light onto a banknote BN having a foreign object BB attached thereto. The sensor unit 400 also includes a light source filter 417, a light receiving filter 418, and an excitation light source light guide 419.

[0159] FIG. 34 is a plan view schematically illustrating an example of the configuration of a substrate included in the image acquisition sensor unit according to the third embodiment.

[0160] 34, the excitation light source 411c has two types of LEDs 420a and 420b arranged alternately on a substrate 414, and the LEDs 420a and 420b are simultaneously lit. The two types of LEDs 420a and 420b have different peak wavelengths, but both are in the wavelength range of 300 to 350 nm. This makes it possible to obtain the excitation light required to cause many foreign substances to emit fluorescence.

[0161] The number of wavelengths used in the excitation light source 411c may be three or more. The excitation light source 411c may be a light source that emits broad light other than an LED. The two types of LEDs 420a and 420b may be arranged in two rows instead of being alternately arranged. The two types of LEDs 420a and 420b may be turned on alternately instead of being turned on simultaneously, and images may be taken individually.

[0162] The light source filter 417 is disposed on the excitation light source 411c and has optical properties that block light in the detection wavelength band required for detecting fluorescence.

[0163] If the light emitted from the excitation light source 411c does not include light in the detection wavelength band, or if the amount of light does not affect detection, the light source filter 417 may be omitted.

[0164] Because adhesive marks from cutting and pasting are distributed in the form of long, thin lines, the resolution of the light receiving unit 413 is, for example, 100 dpi or more in order to effectively detect the adhesive marks. Furthermore, in order to distinguish and determine foreign matter that emits blue light from fluorescent ink that emits light in other colors, the light receiving unit 413 may be equipped with an RGB color filter (see FIG. 13).

[0165] The light-receiving filter 418 is disposed on the end face of the condenser lens 412 on the transport path side, and has optical properties that block light in the wavelength band irradiated by the excitation light source 411c. If the light-receiving unit 413 is not sensitive to the light irradiated from the excitation light source 411c through the light source filter 417, or if the sensitivity does not affect detection, the light-receiving filter 418 may be omitted.

[0166] The cover glass 416 is made of a material that transmits the excitation wavelength of the foreign matter (the wavelength band of the excitation light emitted by the excitation light source 411c) and the wavelength band of the fluorescent light emitted by the foreign matter.

[0167] The excitation light source light guide 419 is used for the purpose of increasing the light irradiation efficiency. The excitation light source light guide 419 has a shape that is slightly curved from the excitation light source 411c toward the end face of the condenser lens 412 on the transport path side, and is made of a material that transmits the excitation wavelength of foreign matter (the wavelength band of the excitation light irradiated by the excitation light source 411c).

[0168] Alternatively, the excitation light source 411c may directly irradiate the banknote BN with excitation light without using the excitation light source light guide 419.

[0169] Furthermore, in Figure 33, a case has been described in which the sensor for detecting fluorescence from foreign matter is integrated with a CIS that collects RGB images and IR images, but the sensor may not be integrated with a CIS and may instead be dedicated to detecting fluorescence from foreign matter.

[0170] Although the embodiments have been described above with reference to the drawings, the present disclosure is not limited to the above-described embodiments. Furthermore, the configurations of the respective embodiments may be appropriately combined or modified without departing from the spirit and scope of the present disclosure. [Industrial Applicability]

[0171] As described above, the present disclosure provides a technique that is useful for detecting laminated sheets with high accuracy. [Explanation of symbols]

[0172] 1, 200: Paper sheet identification device 10: Image acquisition unit 11, 111a, 111b, 411b: Light source 13, 113, 413: Light receiving section 110, 120: Sensor unit 20, 220: Control unit 21, 221: Pre-judgment processing unit 22, 222: Judgment section 23, 223: Abnormal region extraction part 24, 224: Stamped ticket judgment department 40, 240: Judgment area 112, 412: Condenser lens 114, 414: Substrate 131B, 131G, 131R: Light receiving element 131GP:pixels 210: Detection unit 211: Magnetic detection unit 212: Thickness detection unit 225: Fluorescence abnormality determination unit 226: Mask area determination unit 230: Storage section 241: Mask area 242: Fluorescence level calculation area 243: Abnormal area 300: Paper processing equipment 301: Hopper 302: Rejection Department 303:Operation unit 304: Cabinet 305: Display section 306a to 306d: Accumulation section 310: Transport unit 320: Main body control unit 330: Main unit memory section 400: Sensor unit 411c: Excitation light source 415: Case 416: Cover glass 417: Light source filter 418: Light receiving filter 419: Excitation light source guide 420a, 420b: LED 1310: Photodetector 1311B, 1311G, 1311R: Color resist BN:Banknote IMG: Fluorescent image of banknote AA:Joint BB: Foreign body

Claims

1. A paper sheet identification device for identifying paper sheets, an image acquisition unit that acquires a fluorescent image of the paper sheet by irradiating the paper sheet with excitation light and receiving fluorescent light emitted from the paper sheet; a control unit that calculates a fluorescence level specific to the paper sheet from the fluorescence image acquired by the image acquisition unit, extracts an abnormal area in the fluorescence image based on the fluorescence level, and identifies whether the paper sheet is a bonded note based on the abnormal area. A paper sheet identification device characterized by:

2. The control unit calculates a threshold value for an abnormal brightness value in the fluorescence image from the fluorescence level, and extracts a pixel region in the fluorescence image that exceeds the threshold value as the abnormal region.

2. The paper sheet identifying device according to claim 1.

3. The control unit extracts the abnormal region by scanning the fluorescent image in at least one direction selected from a main scanning direction, a sub-scanning direction, and an oblique direction that forms a predetermined angle with respect to the main scanning direction and the sub-scanning direction.

3. The paper sheet identifying device according to claim 1 or 2.

4. The control unit extracts the abnormal region by scanning the fluorescent image in each of the main scanning direction, the sub-scanning direction, and the oblique direction.

4. The paper sheet identifying device according to claim 3.

5. A paper sheet processing apparatus comprising the paper sheet recognition device according to any one of claims 1 to 4.

6. A paper sheet identification method for identifying paper sheets, comprising: an image acquisition step of acquiring a fluorescent image of the paper sheet by irradiating the paper sheet with excitation light and receiving fluorescent light emitted from the paper sheet; a fluorescence level calculation step of calculating a fluorescence level specific to the paper sheet from the fluorescence image acquired in the image acquisition step; an abnormal region extraction step of extracting an abnormal region from the fluorescence image based on the fluorescence level; and a recognition step of identifying whether the paper sheet is a laminated sheet based on the abnormal area. A paper sheet identification method comprising:

Images