Method and apparatus for determining the wear condition of coins

Abstract

The present invention provides a method and apparatus for determining the wear condition of coins. [Solution] A coin wear condition determination method for determining whether a target coin C is worn, comprising: an image acquisition step of acquiring an image of one side of the target coin C; an identification step of identifying the denomination of the target coin and whether the image surface of the target coin C reflected in the image is the front or back side of the coin C by pattern matching the image of

Description

Technical Field

[0001] The present invention relates to a method for determining the wear state of coins and a device for determining the wear state of coins.

Background Art

[0002] Conventionally, devices for discriminating the authenticity of coins, whether a coin is in circulation, and the denomination of coins have been known. For example, in Patent Document 1, a denomination discrimination means discriminates the denomination of a coin based on the diameter and material of the coin, and a data comparison means reads out the reference pattern data of the coin corresponding to the denomination discriminated by the denomination discrimination means from the reference pattern data of the denominations stored in a pattern data storage means in advance, and optically compares the reference pattern data of the coin corresponding to the discriminated denomination with the surface pattern of the coin detected, thereby disclosing a coin discrimination device for accurately discriminating coins.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, there is a need to exclude worn coins (worn coins) from the circulation process. However, the coin discrimination device described in Patent Document 1 has a problem that it cannot determine whether a coin is a worn coin.

[0005] Therefore, a technical problem to be solved in order to determine the wear state of coins arises, and an object of the present invention is to solve this problem.

Means for Solving the Problems

[0006] To achieve the above objective, the coin wear condition determination method according to the present invention is a coin wear condition determination method for determining whether or not a coin is worn, and includes: an imaging step of acquiring an image showing one side of the target coin, which is the coin to be determined; an identification step of identifying the denomination of the target coin and whether the image surface, which is one side of the target coin shown in the image, is the front or back side of the coin by pattern matching the image image with dictionary images of both sides of the coin pre-stored in a storage unit for each denomination; a discrimination step of determining the character portion and the pattern portion engraved on the image surface based on the dictionary image; a calculation step of calculating a comparative brightness value of the target coin based on at least one of the character portion's brightness value and the pattern portion's brightness value in the image image; and a first determination step of determining the target coin as a worn coin with advanced wear if the comparative brightness value falls below a predetermined threshold.

[0007] Furthermore, in order to achieve the above objective, the coin wear condition determination device according to the present invention is a coin wear condition determination device that determines whether or not a coin is worn, and comprises: a storage unit that stores dictionary images of both sides of the coin for each denomination in advance; an image acquisition unit that acquires an image of one side of the target coin, which is the coin to be determined; an identification unit that performs pattern matching between the dictionary image and the image to identify the denomination of the target coin and whether the image surface, which is one side of the target coin shown in the image, is the front or back side of the coin; a discrimination unit that identifies the character portion and the pattern portion engraved on the image surface based on the dictionary image; a calculation unit that calculates a comparative brightness value of the target coin based on at least one of the character portion's brightness value and the pattern portion's brightness value in the image; and a determination unit that determines the target coin to be determined to be a worn coin with advanced wear if the comparative brightness value falls below a predetermined threshold. [Effects of the Invention]

[0008] This invention makes it possible to determine whether a coin is worn or not. [Brief explanation of the drawing]

[0009] [Figure 1] A plan view of the coin determination portion of a coin wear condition determination device according to one embodiment of the present invention. [Figure 2] Side view of the coin wear condition detection section of the coin wear condition detection device. [Figure 3] Functional block diagram of the main components of a coin wear condition determination device. [Figure 4] A flowchart showing the procedure for determining the wear condition of coins. [Figure 5] This figure shows an example of transformation pattern data converted to the rθ coordinate system when the imaging surface is the year-printed side of a 100-yen coin. [Figure 6] This figure shows an example of transformation pattern data converted to the rθ coordinate system when the imaging surface is the cherry blossom side of a 100-yen coin. [Figure 7] A diagram showing an example of standard pattern data for the year-of-the-year side of a 100-yen coin. [Figure 8] A diagram showing an example of the standard pattern data for the cherry blossom side of a 100-yen coin. [Figure 9] This diagram shows an example of a 100-yen coin viewed from the side with the year inscribed on it. [Figure 10] An example of a 100-yen coin viewed from the cherry blossom side. [Figure 11] A graph showing the percentage of worn-out coins by year of manufacture. [Figure 12] A schematic diagram showing how light reflects off the edges of the lettering or patterns on a coin. [Figure 13] A schematic diagram showing how light scatters at the edges of the lettering or patterns on worn coins. [Figure 14] A schematic diagram showing the relationship between the brightness value of the lettering on a coin and the angle at an arbitrary distance from the data center in the rθ coordinate system. [Figure 15] This diagram shows an example of edge detection locations when the image surface is the year-of-year side of a 100-yen coin. [Figure 16] This diagram shows an example of edge detection locations when the imaging surface is the cherry blossom side of a 100-yen coin. [Figure 17] A histogram showing the results of a simulation of the number of 100-yen coins for each type of brightness value of the characters included in the year mark. [Figure 18] A histogram showing the result of simulating the number of 100 - yen coins for each type luminance value of the pattern part included in the year - number face. [Figure 19] A histogram showing the number of 100 - yen coins for each comparison luminance value obtained by adding up the histograms shown in FIGS. 17 and 18. [Figure 20] A diagram showing a selection screen where the wear - state determination value can be arbitrarily changed.

Mode for Carrying Out the Invention

[0010] The coin wear - state determination device according to an embodiment of the present invention will be described based on the drawings. In the following, when referring to the number of components, numerical values, amounts, ranges, etc., unless specifically stated or limited to a specific number in principle, it is not limited to that specific number, and it may be more or less than the specific number.

[0011] Also, when referring to the shape, positional relationship of components, etc., unless specifically stated or it is considered otherwise in principle, it includes those substantially approximated or similar to the shape, etc.

[0012] Also, the drawings may exaggerate by enlarging characteristic parts etc. for easy understanding of the characteristics, and the dimensional ratios of components etc. are not necessarily the same as the actual ones.

[0013] <Configuration of Coin Wear - State Determination Device> FIG. 1 is a plan view of the coin determination part of the coin wear - state determination device 1 according to the present embodiment, and FIG. 2 is a side view thereof. The coin wear - state determination device 1 includes a coin conveyance path 2 and an endless belt - like conveyance belt 3 provided so as to extend along the coin conveyance path 2 above the coin conveyance path 2. The coin conveyance path 2 is formed to have a width for arranging the coins C fed out from the upstream side in a line in the extending direction of the coin conveyance path 2. The conveyance belt 3 can convey the coins C on the coin conveyance path 2 along the conveyance direction A while pressing them against the surface of the coin conveyance path 2. A pair of guide rails 4 for guiding the movement of the coins C are provided on both sides of the coin conveyance path 2.

[0014] The coin transport path 2 is provided with a transparent passage section 5 made of a light-transmitting transparent material such as glass or acrylic resin. In the transport direction A, a pair of magnetic sensors 6 for detecting the magnetic properties of the coins C are provided on the upstream side of the transparent passage section 5.

[0015] In the transport direction A, two sets of timing sensors 7 are provided downstream of the center of the transparent passage section 5 to detect when a coin C reaches the transparent passage section 5. Each timing sensor 7 includes a light-emitting element 8 that emits light from above the transparent passage section 5 toward the transparent passage section 5, and a light-receiving element 9 that can receive the light emitted from the light-emitting element 8 that has passed through the transparent passage section 5. The light-receiving element 9 outputs a timing signal when the light emitted from the light-emitting element 8 is blocked by the coin C being transported on the surface of the transparent passage section 5 and the light emitted from the light-emitting element 8 is not received. The timing sensors 7 are positioned relative to the image generation unit 12, which will be described later, so that when the light-receiving element 9 outputs the timing signal, the center of the coin C on the surface of the transparent passage section 5 coincides with the center of the transparent passage section 5.

[0016] Below the transparent passage section 5, an image acquisition unit 10 is provided to acquire an image of the underside of a coin C being transported on the surface of the transparent passage section 5. The image acquisition unit 10 is provided on the back side of the transparent passage section 5 and includes a light-emitting unit 11 that irradiates light onto the coin C passing through the transparent passage section 5, and an image generation unit 12 provided below the light-emitting unit 11 that receives the light emitted from the light-emitting unit 11 and reflected by the coin C, and generates an image of the underside of the coin C.

[0017] The light-emitting section 11 is equipped with a number of light-emitting elements 13, such as LEDs, arranged on a circle centered on the center of the transparent passage section 5. Each light-emitting element 13 is positioned so that its optical axis forms a small angle with respect to the horizontal direction and points towards a predetermined point on the central axis of the circle centered on the center of the transparent passage section 5, thereby enabling it to irradiate light onto a coin C passing over the transparent passage section 5 at a shallow angle.

[0018] The image generation unit 12 includes a lens system 14 whose optical axis coincides with the central axis of a circle centered on the center of the transparent passage 5, a CCD 15 located below the lens system 14 with its focal point located on the upper surface of the transparent passage 5, which photoelectrically detects light emitted from the light-emitting element 13 and reflected from the lower surface of the coin C, and an A / D converter 16, described later, which converts the image data of the coin C detected by the CCD 15 into a digital signal and outputs digitized image data (captured image) of the coin C.

[0019] Figure 3 is a functional block diagram of the main components of the coin wear condition determination device 1. The image acquisition unit 10 includes a light emission control unit 17 and an image reading control unit 18.

[0020] When the light emission control unit 17 receives a timing signal from the timing sensor 7, it outputs a light emission signal to the light emission unit 11, causing it to emit light and irradiate the coin C located on the upper surface of the transparent passage 5.

[0021] When the image reading control unit 18 receives a timing signal from the timing sensor 7, it causes the CCD 15 to start detecting the light reflected by the bottom surface of the coin C.

[0022] The coin wear condition determination device 1 includes a control unit 19. The control unit 19 is a microcontroller composed of, for example, a CPU, memory, etc., and includes a control unit 20, a storage unit 21, and an I / O port 22.

[0023] The control unit 20 controls each of the components that make up the coin wear condition determination device 1. The storage unit 21 is equipped with ROM, RAM, etc., and stores processing programs for controlling the components of the coin wear condition determination device 1. The I / O ports 22 are connected to the components that make up the coin wear condition determination device 1. The functions of the control unit 19 may be realized by control using software or by operation using hardware.

[0024] The control unit 20 is functionally divided into a coin denomination estimation unit 23, a coin position determination unit 24, a data conversion unit 25, a specific unit 26, a discrimination unit 27, a calculation unit 28, a first determination unit 29, and a second determination unit 30. Hereinafter, the coin whose wear condition is determined by the coin wear condition determination device 1 will be referred to as the "coin to be determined".

[0025] The coin denomination estimation unit 23 accesses the storage unit 21 based on the detection signal from the magnetic sensor 6, compares the magnetic data indicating the magnetic properties of each coin C stored in the storage unit 21 with the magnetic data of the target coin C input by the detection signal from the magnetic sensor 6, and estimates the candidate coin denominations of the target coin C detected by the magnetic sensor 6.

[0026] Furthermore, the denomination estimation unit 23 reads from the storage unit 21 the captured image (image pattern data) of the target coin C that has been generated by the image generation unit 12 and stored in the storage unit 21 in a Cartesian coordinate system, i.e., an xy coordinate system. The unit compares the image pattern data of the target coin C read from the storage unit 21 with the data on the diameter of each denomination of coin C stored in the storage unit 21, and estimates the candidate denomination of the target coin C based on its diameter.

[0027] The denomination estimation unit 23 then estimates candidate denominations for the target coin C based on the denomination of the target coin C estimated based on the magnetic data and the denomination of the target coin C estimated based on the diameter data.

[0028] The coin position determination unit 24 calculates the center coordinates and diameter of the coin to be determined C that appear in the captured image, and detects the position of the coin to be determined C in the captured image.

[0029] The data conversion unit 25 generates converted pattern data D2 by transforming the image pattern data of the target coin C into a polar coordinate system, i.e., an rθ coordinate system, based on the center coordinates of the image pattern data calculated by the coin position determination unit 24.

[0030] The identification unit 26 reads the reference pattern data D1 of the coin C corresponding to the denomination estimated by the denomination estimation unit 23 from the reference pattern data D1 of each denomination of coin C stored in the storage unit 21, compares this reference pattern data D1 with the transformed pattern data D2 which has been transformed into the rθ coordinate system by the data transformation unit 25 (pattern matching), and identifies the denomination of the coin C to be determined, as well as whether the bottom surface of the coin C to be determined (hereinafter referred to as the imaging surface) is the front or back surface. The storage unit 21 has reference pattern data D1 for each denomination and corresponding to both sides (front and back) of the coin C, which are expanded into the rθ coordinate system and stored in advance.

[0031] The discrimination unit 27 reads from the storage unit 21 reference pattern data D1, which is unfolded in the rθ coordinate system of the front or back surface of the coin C corresponding to the imaging surface of the coin C to be judged, based on the identification result of the identification unit 26, and determines at least one of the character portion and the pattern portion engraved on the imaging surface of the coin C to be judged. The reference pattern data D1 stored in the storage unit 21 in advance contains data values ​​that identify the positions of the pattern portion and character portion engraved on both sides of the coin C, respectively.

[0032] The calculation unit 28 calculates a comparative brightness value of the coin C to be judged based on the brightness value of at least one of the character portion and the pattern portion in the captured image.

[0033] The first determination unit 29 reads threshold data D3, which indicates a threshold value for brightness, from the storage unit 21. If the comparison brightness value calculated by the calculation unit 28 falls below the threshold, the unit determines that the coin C to be judged is a worn coin with advanced wear. The threshold is a wear state determination value set for the front and back surfaces of coin C for each denomination. Multiple wear state determination values ​​may be set depending on the degree of wear of coin C, and in this case, the threshold can be arbitrarily changed among the multiple wear state determination values.

[0034] The second determination unit 30 determines that the coin to be determined C is a worn coin if the characters indicating the manufacturing date of the coin to be determined C contained in the character portion of the coin to be determined C match the manufacturing date information of the coin estimated to be a worn coin read from the storage unit 21.

[0035] The coin wear condition determination device 1 includes a display unit 31 and an input unit 32. The display unit 31 displays the determination result of the coin C to be determined, or displays an operation screen for operating the coin wear condition determination device 1. The input unit 32 receives operation input from the operator to the coin wear condition determination device 1, and if the threshold can be arbitrarily changed between multiple wear condition determination values, it receives operation input from the operator to select a desired wear condition determination value. The display unit 31 and the input unit 32 may be, for example, a capacitive touch panel display.

[0036] <Procedure for determining the wear condition of coins> Next, the procedure for determining whether the target coin C is a worn coin will be explained based on the diagram. Figure 4 is a flowchart showing the procedure for determining the wear condition of a coin. In the following explanation, we will use the case where the target coin C is a 100 yen coin as an example, but it may be a coin of other denominations.

[0037] First, dictionary images of both sides of coin C for each denomination are stored in the memory unit 21 (step S1: memory step). The dictionary images include reference pattern data D1 obtained by transforming the captured images of both sides (front and back) of coin C, which serve as the judgment criteria, into rθ coordinates.

[0038] Next, the image acquisition unit 10 captures the imaging surface of the coin to be judged C as it is transported along the transport direction A on the surface of the transparent passage 5 (Step S2: Imaging step).

[0039] Specifically, first, the coin to be judged C is pressed against the surface of the coin transport path 2 by the transport belt 3 and transported along a pair of guide rails 4 within the coin transport path 2. When the coin to be judged C reaches the transparent passage section 5 and blocks the light emitted from the light-emitting element 8, and the light-receiving element 9 stops receiving light from the light-emitting element 8, the timing sensor 7 outputs a timing signal to the light emission control unit 17 and the image reading control unit 18.

[0040] When the light emission control unit 17 receives a timing signal from the timing sensor 7, it outputs a light emission signal to the light emission unit 11, and the light-emitting element 13 emits light toward the lower surface of the coin C to be judged, which is located on the transparent passage 5.

[0041] When the image reading control unit 18 receives a timing signal from the timing sensor 7, it outputs a reading start signal to the CCD 15, and the CCD 15 starts reading the reflected light of the coin C to be judged. The image pattern data of the coin C to be judged, generated by the CCD 15 and converted into a digital signal by the A / D converter 16, is expanded into an xy coordinate system and stored in the storage unit 21.

[0042] Next, the denomination estimation unit 23 estimates the denomination of the coin to be determined C that is being transported along the transport direction A on the surface of the transparent passage section 5 (Step S3: Denomination Estimation Step).

[0043] Specifically, a pair of magnetic sensors 6 detect the magnetic properties of the coin to be judged C as it is being transported through the coin transport path 2, and output a detection signal to the coin denomination estimation unit 23. Based on the detection signal from the magnetic sensors 6, the coin denomination estimation unit 23 accesses the storage unit 21 and compares the magnetic data indicating the magnetic properties of each coin denomination stored in the storage unit 21 with the magnetic data of the coin to be judged C input via the detection signal from the magnetic sensors 6 to estimate candidate coin denominations of the coin to be judged C detected by the magnetic sensors 6.

[0044] Furthermore, the denomination estimation unit 23 compares the image pattern data of the target coin C read from the memory unit 21 with the data on the diameter of each denomination of coins stored in the memory unit 21, and estimates the candidate denomination of the target coin C based on the diameter of the target coin C.

[0045] Then, if the estimation result based on magnetic data and the estimation result based on diameter data match, the denomination estimation unit 23 estimates that denomination as the denomination of the coin C to be judged. If the estimation result based on magnetic data and the estimation result based on diameter data do not match, the denomination estimation unit 23 may estimate each denomination as the denomination of the coin C to be judged, or it may treat the coin C to be judged as a rejected coin with an unknown denomination.

[0046] Furthermore, the denomination estimation unit 23 is not limited to estimating the denomination of the target coin C based on both magnetic data and diameter data; it may also estimate the denomination of the target coin C based on at least one of the magnetic data and diameter data, or it may estimate the denomination of the target coin C based on other data. Furthermore, step S3 may be executed in parallel with step S2 or before step S2.

[0047] Next, the coin position determination unit 24 detects the position of the coin C to be determined in the captured image (Step S4: Coin position determination step).

[0048] Specifically, the coin position determination unit 24 searches for at least three edge points of the target coin C from the outside of the captured image toward the center. From three of the searched edge points, it calculates virtual circles, and the average coordinates obtained by averaging the center coordinates of each virtual circle are used as the center coordinates (xc, yc) of the data center of the target coin C. The average diameter obtained by averaging the diameters of each virtual circle is used as the diameter of the target coin C. This detects the position of the target coin C in the captured image. Step S4 may be executed in parallel with or before step S3. If steps S3 and S4 are executed in parallel, for example, the diameter data of the target coin C used in step S3 may be used as the diameter of the target coin C calculated in step S4.

[0049] Next, the identification unit 26 identifies the denomination of the coin C to be determined and determines whether the image surface of the coin C to be determined is the front or back side (step S5: identification step).

[0050] Specifically, first, the data conversion unit 25 generates converted pattern data D2 by converting the image pattern data stored in the storage unit 21, which is expanded in the xy coordinate system, to the rθ coordinate system based on the center coordinates (xc, yc) of the pattern data of the target coin C in the captured image calculated by the coin position determination unit 24. Figure 5 shows an example of converted pattern data D2 converted to the rθ coordinate system when the imaging surface is the front side (year side) of a 100-yen coin, and Figure 6 shows an example of converted pattern data D2 converted to the rθ coordinate system when the imaging surface is the back side (cherry blossom side) of a 100-yen coin. In Figures 5 and 6, the vertical axis is the distance r from the data center in the xy coordinate system, and the horizontal axis is the angle θ around the data center.

[0051] Next, the identification unit 26 reads the reference pattern data D1 for the front and back of the coin C corresponding to the denomination estimated by the denomination estimation unit 23 from the dictionary images stored in the memory unit 21. Figure 7 shows an example of the reference pattern data D1 for the front (year side) of a 100-yen coin, and Figure 8 shows an example of the reference pattern data D1 for the back (cherry blossom side) of a 100-yen coin. In Figures 7 and 8, the vertical axis is the distance r from the data center in the xy coordinate system, and the horizontal axis is the angle θ around the data center. Note that the text portion is omitted in Figures 7 and 8.

[0052] Next, the identification unit 26 compares (pattern matching) the reference pattern data D1 for the front and back surfaces of coin C corresponding to the denomination estimated by the denomination estimation unit 23 with the transformed pattern data D2 that has been coordinate-transformed to the rθ coordinate system by the data conversion unit 25. The identification unit 26 identifies the denomination corresponding to the reference pattern data D1 with the highest matching value between the transformed pattern data D2 and the reference pattern data D1 whose matching value is equal to or greater than a predetermined value as the denomination of the coin C to be judged, and identifies the front or back surface corresponding to that reference pattern data D1 as the imaging surface. If the matching value between the reference pattern data D1 and the transformed pattern data D2 is not sufficiently high, the denomination of the coin C to be judged cannot be identified, and the identification unit 26 determines the coin C to be judged as a rejected coin of unknown denomination.

[0053] Generally, the conversion pattern data D2 is offset in the horizontal direction, or θ-axis direction, relative to the reference pattern data D1. Prior to pattern matching by the specific unit 26, the θ-axis direction deviation of the conversion pattern data D2 caused by the circumferential offset of the coin C to be judged is corrected. The method for correcting the θ-axis direction deviation of the conversion pattern data D2 is the same as the method described in Japanese Patent Application Publication No. 8-36661.

[0054] Next, the discrimination unit 27 identifies the characters and patterns engraved on the imaging surface of the coin C to be judged (Step S6: Discrimination step).

[0055] If the reference pattern data D1 includes a pattern, the pattern in the reference pattern data D1 and the pattern in the converted pattern data D2, which has been corrected for the θ-axis displacement from the reference pattern data D1, will coincide in the pattern data. Therefore, the discrimination unit 27 identifies the pattern in the converted pattern data D2 from the data value that identifies the position of the pattern in the reference pattern data D1. Furthermore, since the positional relationship between the pattern and the character is the same in the reference pattern data D1 and the converted pattern data D2 with the θ-axis displacement corrected, the character can be identified from the position of the pattern on the converted pattern data D2 with the θ-axis displacement corrected. In other words, the discrimination unit 27 identifies the character in the converted pattern data D2 based on the identified position of the pattern on the converted pattern data D2.

[0056] Similarly, if the reference pattern data D1 includes a character portion, the character portion included in the reference pattern data D1 and the character portion included in the converted pattern data D2, which has been corrected for the θ-axis deviation from the reference pattern data D1, will coincide on the pattern data. Therefore, the discrimination unit 27 may determine the character portion included in the converted pattern data D2 from the data value that identifies the position of the character portion included in the reference pattern data D1, and then determine the pattern portion included in the converted pattern data D2 based on the determined position of the character portion on the converted pattern data D2.

[0057] Next, if the imaging surface of the coin to be judged C, as determined by the discrimination unit 27, is the year side (Yes in step S7), the second discrimination unit 30 reads the characters indicating the manufacturing date of the coin to be judged C from the character portion of the coin to be judged C (step S8: reading step).

[0058] Figure 9 shows an example of a 100-yen coin viewed from the obverse (year side), and Figure 10 shows an example of a 100-yen coin viewed from the reverse (cherry blossom side). As shown in Figure 9, the year side of the 100-yen coin has characters indicating the manufacturing date (Showa 42 in Figure 9) engraved on it. On the other hand, as shown in Figure 10, the cherry blossom side of coin C does not have characters indicating the manufacturing date of coin C engraved on it. Therefore, if the image surface of the target coin C identified by the discrimination unit 27 is the year side, the second discrimination unit 30 reads and extracts characters such as the era name indicating the manufacturing date of the target coin C, which are included in the character part of the year side, from the conversion pattern data D2. One possible method for extracting the characters indicating the manufacturing date of the target coin C from the transformed pattern data D2 is to first extract the coordinates of the characters indicating the manufacturing date of the target coin C from the reference pattern data D1, which has been transformed in advance to the rθ coordinate system shown in Figure 7, and then extract the characters at the coordinates corresponding to the characters indicating the manufacturing date of the target coin C extracted from the reference pattern data D1 from the transformed pattern data D2, which has also been transformed to the rθ coordinate system shown in Figure 5.

[0059] Next, the second determination unit 30 reads out time information indicating the manufacturing date of the coin C that is presumed to be worn, which is stored in advance in the storage unit 21, and determines whether the characters indicating the manufacturing date of the coin C included in the character portion of the coin C read out match the time information read out from the storage unit 21 (Step S9: Second determination step).

[0060] Figure 11 is a graph showing the percentage of worn coins for each year of manufacture from 1968 to 2022, for 4,000 100-yen coins as of 2024. According to Figure 11, it can be seen that almost 100% of 100-yen coins manufactured before 1988 are worn coins. Therefore, in this embodiment, "Showa" was set as the period information. Note that the period information may be other than the era name such as Showa, such as the year of manufacture. Also, the era name used as period information is not limited to Showa, but may be arbitrarily selected from Heisei or Reiwa.

[0061] Next, if the time information read from the memory unit 21 matches the characters indicating the manufacturing date of the coin C to be judged (Yes in step S9), the second judgment unit 30 determines that the coin C to be judged is a worn coin with significant wear (step S10). For example, if the manufacturing date engraved on the year side of the coin C to be judged is "Showa," the manufacturing date engraved on the year side of the coin C to be judged matches the time information stored in the memory unit 21, and therefore the second judgment unit 30 determines that the coin C to be judged is a worn coin. Steps S7 to S9 may be omitted if necessary.

[0062] Next, if the image surface of the coin to be judged C identified by the discrimination unit 27 is the cherry blossom side (No in step S7), or if the characters indicating the manufacturing date of the coin to be judged C included in the character part do not match the date information (No in step S9), the calculation unit 28 calculates the comparative brightness value of the coin to be judged C (step S11: calculation step).

[0063] Specifically, first, the calculation unit 28 calculates the respective brightness values ​​(type brightness values) for the character portion and the pattern portion in the captured image determined by the discrimination unit 27. Here, the type brightness value for the character portion is the average value of the brightness values ​​of the reflected light reflected from the corners (edges) of the character portion over the entire character portion, and the type brightness value for the pattern portion is the average value of the brightness values ​​of the reflected light reflected from the corners (edges) of the pattern portion over the entire pattern portion.

[0064] Figure 12 is a schematic diagram showing how light reflects off the angular edges of the lettering or patterned portion of a genuine coin, and Figure 13 is a schematic diagram showing how light scatters off the rounded edges of the lettering or patterned portion of a worn coin. As shown in Figure 12, in a genuine coin that has not undergone significant wear, the light reflected off the angular edges and directed towards the CCD 15 is strong, whereas, as shown in Figure 13, in a worn coin, the light is scattered off the rounded edges, resulting in a relatively weaker reflected light directed towards the CCD 15. Furthermore, there is variation in the intensity of reflected light between the lettering portion and the patterned portion. Therefore, it is preferable to calculate the various luminance values ​​for the lettering portion and the patterned portion in a way that does not affect each other.

[0065] Therefore, the calculation unit 28 calculates the type luminance value of the character portion by following the procedure below. First, in calculating the luminance value of the entire character portion, in order to prevent the reflected light of the pattern portion from having an effect, the pattern portion is masked from the transformed pattern data D2, which has been coordinate-transformed to the rθ coordinate system shown in Figure 5 or Figure 6, and the luminance value of only the character portion is calculated. One possible method for masking the pattern portion from the transformed pattern data D2 is to extract the coordinates of the pattern portion from the reference pattern data D1, which has been coordinate-transformed to the rθ coordinate system shown in Figure 7, and then calculate the luminance value at the coordinates corresponding to the coordinates of the pattern portion extracted from the reference pattern data D1 in the transformed pattern data D2, which has been coordinate-transformed to the rθ coordinate system shown in Figure 5.

[0066] Next, the calculation unit 28 calculates the average value of luminance values ​​(second-order average luminance value) that are equal to or greater than the average value (primary average luminance value) of all luminance values ​​of the character portion in the conversion pattern data D2 within the calculation area for calculating the luminance value of the character portion of the coin C to be judged, as the type luminance value of the character portion. Figure 14 shows a schematic diagram representing the relationship between the luminance value of the character portion of the coin C to be judged at a distance r from the data center in the rθ coordinate system and the angle θ. In Figure 14, the primary average luminance value is shown by a dashed line, the calculation range of the secondary average luminance value is shown by hatching, and the secondary average luminance value, which is the average value within the calculation range of the secondary average luminance value, is shown by a solid line. Since the range below the primary average luminance value, such as the flat surface of the character portion where reflected light tends to be weak, is excluded from the calculation range of the secondary average luminance value, the luminance value of the edge of the character portion can be accurately extracted.

[0067] The calculation unit 28 calculates the type luminance value of the pattern area using the same procedure as for the character area. Specifically, first, in calculating the luminance value of the entire pattern area, the character area is masked out of the transformed pattern data D2, which has been coordinate-transformed to the rθ coordinate system shown in Figure 5 or Figure 6, so that the reflected light from the character area does not have an effect, and the luminance value of only the pattern area is calculated. Next, the calculation unit 28 calculates the type luminance value of the pattern area as the average value (second-order average luminance value) of luminance values ​​that are equal to or greater than the average value (first-order average luminance value) of all luminance values ​​of the pattern area in the transformed pattern data D2 within the calculation target area for calculating the luminance value of the pattern area of ​​the coin C to be judged. Figure 15 shows an example of edge detection locations of the coin C to be judged when the image surface is the year side of a 100 yen coin, and Figure 16 shows an example of edge detection locations of the coin C to be judged when the image surface is the cherry blossom side of a 100 yen coin. In Figures 15 and 16, the white areas show edge detection locations that exhibit high luminance values.

[0068] The calculation unit 28 then calculates a comparative brightness value for the coin C to be judged based on the various brightness values ​​of the character portion and pattern portion in the captured image determined by the discrimination unit 27. The comparative brightness value is calculated, for example, by summing the various brightness values ​​of the character portion and pattern portion.

[0069] Next, the first determination unit 29 reads a threshold value from the storage unit 21 and determines whether the comparison brightness value falls below this threshold value (step S12: first determination step).

[0070] Specifically, the first determination unit 29 reads out the wear state determination values ​​from the wear state determination values ​​pre-stored in the memory unit 21, using the wear state determination values ​​corresponding to the denomination of the target coin C and the imaging surface of the target coin C, which were determined in step S5, as threshold values. The wear state determination values ​​are set for each denomination and for both sides (front and back) of the coin C, and are acquired in advance through experiments or the like and stored in the memory unit 21.

[0071] Figure 17 is a histogram showing the results of a simulation of the number of 100-yen coins for each type of brightness value of the characters on the year side, for 4000 coins. Figure 18 is a histogram showing the results of a simulation of the number of 100-yen coins for each type of brightness value of the pattern on the year side, for the same 4000 coins as in Figure 17. Figure 19 is a histogram showing the number of 100-yen coins for each comparison brightness value, combining the results of Figures 17 and 18.

[0072] According to Figure 17, coin C manufactured in the Showa era has a luminance value of 40-80 for the characters on the year side, coin C manufactured in the Heisei era has a luminance value of 50-160 for the characters on the year side, and coin C manufactured in the Reiwa era has a luminance value of 80-160 for the characters on the year side.

[0073] Furthermore, as shown in Figure 18, it can be seen that for coin C manufactured in the Showa era, the type brightness value of the pattern on the year side falls within the range of 50 to 160; for coin C manufactured in the Heisei era, the type brightness value of the pattern on the year side falls within the range of 120 to 180; and for coin C manufactured in the Reiwa era, the type brightness value of the pattern on the year side falls within the range of 160 to 180.

[0074] Furthermore, as shown in Figure 19, coin C manufactured in the Showa era has a comparative brightness value on the year side that falls within the range of 110 to 260, coin C manufactured in the Heisei era has a comparative brightness value on the year side that falls within the range of 160 to 320, and coin C manufactured in the Reiwa era has a comparative brightness value on the year side that falls within the range of 200 to 320. Therefore, by setting the threshold value for the comparative brightness value on the year side to a value greater than the upper limit of the comparative brightness value for coin C manufactured in the Showa era, for example, 270, it is possible to easily identify coin C manufactured in the Showa era that is presumed to be showing signs of wear. It should be noted that the brightness values ​​and threshold values ​​mentioned above are merely examples and will vary depending on the denomination of the coin C being judged, the type of the transport surface, and the time of judgment.

[0075] Then, if the comparison brightness value is above the threshold (Yes in step S12), the first determination unit 29 determines that the coin C to be judged is a genuine coin that has not undergone significant wear (step S13). On the other hand, if the comparison brightness value is below the threshold (No in step S12), the first determination unit 29 determines that the coin C to be judged is a worn coin that has undergone significant wear (step S10).

[0076] Furthermore, in order to perform wear determination in detail according to the progress of wear on the target coin C, multiple wear state determination values ​​may be set according to the progress of wear on coin C. In this case, the operator sets in advance which wear state determination value to use as a threshold via the input unit 32. Figure 20 shows the selection screen SS1 displayed on the display unit 31, which allows the wear state determination value (indicated as "image wear level" in Figure 20) to be arbitrarily changed between multiple levels. In this embodiment, 101 wear state determination values ​​are set in increments of 1 from level 0 to 100, with level 0 corresponding to the smallest wear state determination value and level 100 corresponding to the largest wear state determination value.

[0077] The selection screen SS1 is composed of the following, arranged from top to bottom: the first adjustment bar G1, which has the number "500" on the left and allows adjustment of the wear judgment value of a 500 yen coin in one step at a time; the second adjustment bar G2, which has the number "100" on the left and allows adjustment of the wear judgment value of a 100 yen coin in one step at a time; the third adjustment bar G3, which has the number "50" on the left and allows adjustment of the wear judgment value of a 50 yen coin in one step at a time; the fourth adjustment bar G4, which has the number "10" on the left and allows adjustment of the wear judgment value of a 10 yen coin in one step at a time; the fourth adjustment bar G5, which has the number "5" on the left and allows adjustment of the wear judgment value of a 5 yen coin in one step at a time; and the fifth adjustment bar G6, which has the number "1" on the left and allows adjustment of the wear judgment value of a 1 yen coin in one step at a time. Additionally, the lower section of the selection screen SS1 includes icon G7 labeled "Initialize," which resets the selected wear condition judgment value to its initial value, and icon G8 labeled "Confirm," which confirms the selected wear condition judgment value.

[0078] When the selection screen SS1 is displayed on a touch panel display or the like that serves as both the display unit 31 and the input unit 32, the operator presses and inputs the wear condition judgment value for each metal type via the plus (+) or minus (-) icons on the adjustment bars G1 to G6, and after completing the selection, presses the icon G8 labeled "Confirm" to confirm the entered wear condition judgment value. The first judgment unit 29 then reads the wear condition judgment value selected on the selection screen SS1 from the 10 levels of wear condition judgment values ​​from the storage unit 21 as a threshold value and compares it with the comparison brightness value.

[0079] Thus, the coin wear condition determination device 1 according to this embodiment is a coin wear condition determination device 1 that determines whether or not a target coin C is worn, and comprises: a storage unit 21 that stores dictionary images of both sides of coin C for each denomination in advance; an image acquisition unit 10 that acquires an image of the imaging surface of the target coin C; an identification unit 26 that performs pattern matching between the dictionary image and the image to identify the denomination of the target coin C and whether the imaging surface of the target coin C shown in the image is the front or back of coin C; a discrimination unit 27 that identifies the character portion and the pattern portion engraved on the imaging surface based on the dictionary image; a calculation unit 28 that calculates a comparative brightness value of the target coin C based on at least one of the character portion type brightness value and the pattern portion type brightness value in the image; and a first determination unit 29 that determines the target coin C is a worn coin if the comparative brightness value falls below a predetermined threshold.

[0080] According to this configuration, a comparative brightness value of the target coin C, calculated based on at least one of the character brightness values ​​and pattern brightness values ​​in an image captured showing either the front or back of the target coin, is compared with a predetermined threshold. If the comparative brightness value falls below the threshold, the target coin is determined to be a worn coin, thereby easily determining whether a coin is worn or not.

[0081] Furthermore, the coin wear condition determination method according to this embodiment is a coin wear condition determination method for determining whether or not a target coin C is worn, and includes an imaging step of acquiring an image showing one side of the target coin C; an identification step of identifying the denomination of the target coin and whether the image surface of the target coin C shown in the image is the front or back side of the coin C by pattern matching the image with dictionary images of both sides of the coin C that are pre-stored in the storage unit 21 for each denomination; a discrimination step of determining the character portion and the pattern portion engraved on the image surface based on the dictionary image; a calculation step of calculating a comparative brightness value of the target coin C based on at least one of the character portion type brightness value and the pattern portion type brightness value in the image; and a first determination step of determining the target coin as worn if the comparative brightness value falls below a predetermined threshold.

[0082] According to this configuration, a comparative brightness value of the target coin C, calculated based on at least one of the character brightness values ​​and pattern brightness values ​​in an image captured showing either the front or back of the target coin, is compared with a predetermined threshold. If the comparative brightness value falls below the threshold, the target coin is determined to be a worn coin, thereby easily determining whether a coin is worn or not.

[0083] Furthermore, the present invention can be modified in various ways other than those described above, as long as it does not deviate from the spirit of the invention, and it goes without saying that the present invention extends to such modified forms.

[0084] In this embodiment, a histogram of comparative luminance values ​​shown in Figure 19 was used to set an appropriate threshold that can distinguish between the luminance value distribution of coin C manufactured in the Showa era and the luminance value distribution of coin C manufactured in the Heisei or Reiwa era. However, it is conceivable that an appropriate threshold that can distinguish between the luminance value distribution of coin C manufactured in the Showa era and the luminance value distribution of coin C manufactured in the Heisei or Reiwa era can be set using only the histogram of either the character portion or the pattern portion. In such cases, it is not necessarily required to distinguish between both the character portion and the pattern portion in step S6, and it is not necessarily required to obtain various luminance values ​​for the character portion and the pattern portion in steps S11 to S12. [Explanation of Symbols]

[0085] 1: Coin wear condition determination device, 2: Coin transport path, 3: Transport belt, 4: Guide rail, 5: Transparent passage section, 6: Magnetic sensor, 7: Timing sensor, 8: Light-emitting element, 9: Light-receiving element, 10: Image acquisition unit, 11: Light-emitting unit, 12: Image generation unit, 13: Light-emitting element, 14: Lens system, 15: CCD, 16: A / D converter, 17: Light emission control unit, 18: Image reading control unit, 19: Control unit, 20: Control unit, 21: Memory unit, 22: I / O port, 23: Denomination estimation unit, 24: Coin position determination unit, 25: Data conversion unit, 26: Identification unit, 27: Discrimination unit, 28: Calculation unit, 29: First determination unit, 30: Second determination unit, 31: Display unit, 32: Input unit

Claims

1. A method for determining whether a coin is worn or not, The imaging step involves acquiring an image of one side of the coin to be judged, which is the coin to be judged. The identification step involves pattern matching the captured image with dictionary images of both sides of the coin pre-stored in the memory unit for each denomination to determine the denomination of the coin to be determined, and whether the image surface, which is one side of the coin to be determined as seen in the captured image, is the front or back side of the coin. A discrimination step of determining the character portion and pattern portion engraved on the imaging surface based on the dictionary image, A calculation step of calculating the comparative brightness value of the coin to be judged based on at least one of the type brightness value of the character portion and the type brightness value of the pattern portion in the captured image, If the comparison brightness value falls below a predetermined threshold, the first determination step is to determine that the coin to be judged is a worn coin with advanced wear. A method for determining the wear condition of a coin, characterized by including the following:

2. The coin wear condition determination method according to claim 1, characterized in that the threshold is a wear condition determination value set for the front and back surfaces of the coin for each denomination.

3. Multiple wear condition determination values ​​are set according to the degree of wear of the coin. The coin wear condition determination method according to claim 2, characterized in that the threshold can be arbitrarily changed among a plurality of wear condition determination values.

4. In the calculation step described above, various luminance values ​​for the character portion and the pattern portion are calculated. The coin wear condition determination method according to claim 1, characterized in that the first determination step involves adding various brightness values ​​of the character portion and the pattern portion to calculate the comparative brightness value.

5. The coin wear condition determination method according to claim 1, characterized in that the calculation step involves calculating a primary average brightness value, which is the average value of the brightness values ​​of the character portion within the calculation target area of ​​the captured image, and calculating a secondary average brightness value, which is the average value of brightness values ​​of the character portion within the brightness value calculation target area that are equal to or greater than the primary average brightness value, as the type brightness value of the character portion.

6. The coin wear condition determination method according to claim 1, characterized in that the calculation step involves calculating a primary average luminance value which is the average value of the luminance values ​​of the patterned portion within the calculation target area of ​​the captured image, and calculating a secondary average luminance value which is the average value of the luminance values ​​of the patterned portion within the luminance value calculation target area that are equal to or greater than the primary average luminance value, as the type luminance value of the patterned portion.

7. In the memory step, time information indicating the manufacturing date of the coin during which wear is estimated to have progressed is stored in the memory unit. A reading step of reading the characters indicating the manufacturing date of the coin to be determined, which are included in the character portion, A second determination step in which, if the characters indicating the manufacturing period included in the character portion match the period information stored in the memory unit, the coin to be determined is determined to be a worn coin, The method for determining the wear condition of a coin according to claim 1, further comprising the following:

8. The coin wear condition determination method according to claim 7, characterized in that the aforementioned time information is the Japanese era name.

9. A coin wear condition determination device that determines whether or not a coin is worn, A storage unit that pre-stores dictionary images of both sides of the coin for each denomination, An image acquisition unit acquires an image of one side of the coin to be judged, which is the coin to be judged. A identifying unit that performs pattern matching between the dictionary image and the captured image to identify the denomination of the coin to be determined, and whether the image surface, which is one side of the coin to be determined as seen in the captured image, is the front or back side of the coin. A discrimination unit that identifies the character portion and pattern portion engraved on the imaging surface based on the dictionary image, A calculation unit that calculates the comparative brightness value of the coin to be judged based on at least one of the type brightness value of the character portion and the type brightness value of the pattern portion in the captured image, If the comparison brightness value falls below a predetermined threshold, the determination unit determines that the coin to be judged is a worn coin with advanced wear. A coin wear condition determination device characterized by being equipped with the following features.

10. It further includes an input section that can accept operation input from the operator, The coin wear condition determination device according to claim 9, characterized in that the threshold can be arbitrarily changed via the input unit between a plurality of wear condition determination values ​​set for each denomination of coin on the front and back surfaces, respectively, according to the degree of wear of the coin.

Images