Code formation method and information code

Abstract

To provide a code forming method for forming information code for which convenience can be ensured, for example.SOLUTION: A code for concealment CdS is an information code that records information by the arrangement of a bright color cell Cew and a dark color cell Ceb. A code forming method for forming such a code for concealment CdS on a stamp member BM includes a light-emitting layer forming step and a laser stamping step. In the light-emitting layer forming step, a light-emitting layer 50 including a formation range CA of the code for concealment CdS is formed by applying an application agent containing a reaction paint reacting to invisible light to emit light on the stamp member BM. In the laser stamping step, a portion of the light-emitting layer 50 corresponding to the dark color cell Ceb is irradiated with a laser beam to reduce a light-emitting function of the dark color cell Ceb compared to that of the bright color cell Cew.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The disclosure of this specification relates to a technology for an information code for recording information. [Background technology]

[0002] Patent Document 1 discloses a printing method for printing a transparent two-dimensional code using a transparent toner that absorbs infrared light. This two-dimensional code appears and becomes readable when irradiated with infrared light. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-89840 Summary of the Invention [Problem to be solved by the invention]

[0004] In the two-dimensional code disclosed in Patent Document 1, areas where the clear toner is not printed reflect infrared light and become white cells. On the other hand, areas where the clear toner is printed absorb infrared light and become black cells. To capture an image of such a two-dimensional code, a special reading device capable of detecting infrared light is required. As a result, it has become difficult to ensure the usability of the information code.

[0005] The present disclosure aims to provide an information code that ensures convenience and a method for forming such an information code. [Means for solving the problem]

[0006] In order to achieve the above object, one disclosed embodiment is a code forming method for forming an information code (CdS) on a forming target (BM) that records information by an arrangement of light color areas (Cew) and dark color areas (Ceb), in which a light-emitting layer (50) that includes a forming area (CA) of the information code is formed by applying a coating agent containing a reactive paint that emits light in response to invisible light to the forming target (BM) (S50), and by irradiating a laser beam onto a portion of the light-emitting layer that corresponds to the dark color area, By making the invisible light transmittance of the light-emitting layer in the area corresponding to the dark color area higher than the invisible light transmittance of the light-emitting layer in the area corresponding to the light color area, The code forming method includes a step of weakening the luminous function of the dark color area compared to the light color area (S60).

[0007] One disclosed embodiment is an information code that records information by an arrangement of light color regions (Cew) and dark color regions (Ceb), and is an information code that includes an luminescent layer (50) containing reactive paint that emits light in response to invisible light, a strong luminescent section (61) that is located in a position in the luminescent layer that corresponds to the light color region and emits light in response to invisible light, and a weak luminescent section (62) that is located in a position in the luminescent layer that corresponds to the dark color region and has a weaker luminescent function of the reactive paint than the strong luminescent section.

[0008] In these embodiments, the light-emitting function of the portions of the light-emitting layer containing the reactive paint that correspond to the dark regions is weakened compared to the portions that correspond to the light regions. Therefore, when invisible light is irradiated, an arrangement of dark and light regions with different light-emitting intensities appears. As a result, a special reading device is not required to read the information code, ensuring the convenience of the information code.

[0009] It should be noted that the reference numbers in parentheses above and in the claims merely indicate an example of the correspondence with the specific configurations in the embodiments described below, and do not limit the technical scope in any way. Furthermore, claims not explicitly stated in the claims may be combined together if no particular problems arise in the combination. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 illustrates a concealment code according to an embodiment of the present disclosure. [Figure 2] FIG. 1 is a diagram showing an overall view of a case where a traceability system is operated together with an existing distribution management system. [Figure 3] 10 is a flowchart showing details of a code generation process for generating a confidentiality code. [Figure 4] FIG. 10 is a diagram showing details of a transmittance test for explaining the mechanism by which the light-emitting function is weakened by irradiation with laser light. [Figure 5] 10A and 10B are diagrams showing the difference in the surface state and light emission state of the light emitting layer when the output of the laser light is changed. [Figure 6] 6 is a table showing processing conditions for the test shown in FIG. 5. [Figure 7] 6 is a table showing the observation conditions of the sample images shown in FIG. 5. [Figure 8] 10 is a table showing measurement conditions for measuring the depth of an irradiated area and a non-irradiated area. [Figure 9] 1 is a table showing the measurement conditions for color intensity. DETAILED DESCRIPTION OF THE INVENTION

[0011] The information code according to one embodiment of the present disclosure shown in FIG. 1 is a concealment code CdS for recording concealed information. The concealment code CdS is formed on an object to be formed, such as a resin part or a metal part (hereinafter referred to as a stamped part BM), together with a disclosure code CdP for recording public information. The disclosure code CdP and the concealment code CdS are engraved at intervals on a flat surface FA of the stamped part BM by laser marking. The flat surface FA may be a portion where the base material of the stamped part BM is exposed, or may be a painted surface of the stamped part BM. The disclosure code CdP and the concealment code CdS are two-dimensional codes such as a QR code (registered trademark). The disclosure code CdP and the concealment code CdS each record information using a two-dimensional array of multiple cells Ce, each including light-colored cells Cew and dark-colored cells Ceb.

[0012] The public code CdP is a two-dimensional code (visible code) that can be seen with the normal naked eye. The light cells Cew of the public code CdP are the parts that are not irradiated with laser light and remain in their original state. On the other hand, the dark cells Ceb of the public code CdP are the parts where the surface of the base material has been altered by irradiation with laser light. The public code CdP makes it possible to read the public information by utilizing the difference in brightness (difference in visible light reflectance) that occurs between the unaltered light cells Cew and the altered dark cells Ceb.

[0013] Unlike the public code CdP, the concealment code CdS is a two-dimensional code (invisible code) that cannot be seen with the normal naked eye. The concealment code CdS can be read by irradiating it with invisible light in a specific wavelength range. When invisible light is not irradiated, the concealment code CdS is substantially invisible. For example, when ultraviolet light is irradiated using an ultraviolet light source 24 (see Figure 2) such as a black light, the concealment code CdS becomes readable by emitting visible light.

[0014] Specifically, the concealment code CdS includes a light-emitting layer 50, a strong light-emitting portion 61, and a weak light-emitting portion 62. The light-emitting layer 50 contains an ultraviolet-sensitive paint (described in detail below) that emits light in response to ultraviolet light. The light-emitting layer 50 is formed as a thin film covering an area of ​​the flat portion FA that includes the area CA where the concealment code CdS is formed. The strong light-emitting portion 61 is located in a portion of the light-emitting layer 50 that corresponds to the bright cell Cew. The strong light-emitting portion 61 is a portion that is not irradiated with laser light. On the other hand, the weak light-emitting portion 62 is located in a portion of the light-emitting layer 50 that corresponds to the dark cell Ceb. The weak light-emitting portion 62 is a portion where the light-emitting function of the ultraviolet-sensitive paint is weakened by irradiation with laser light compared to the strong light-emitting portion 61. The concealment code CdS enables reading of the concealment information by utilizing the difference in brightness (difference in luminance) between the bright cell Cew formed by the strong light-emitting portion 61, which can emit light strongly, and the dark cell Ceb formed by the weak light-emitting portion 62, which has a reduced light-emitting function.

[0015] The public code CdP is a two-dimensional code used in the distribution management system 110 shown in Fig. 2. On the other hand, the secret code CdS is a two-dimensional code used in the traceability system 120. Note that the public code CdP may be used in both the distribution management system 110 and the traceability system 120.

[0016] <Supply Chain Management System> The distribution management system 110 and the traceability system 120 are management systems that manage a supply chain SC that is constructed including a large number of traders TR. The supply chain SC is a connection between traders for delivering industrial products, agricultural products, marine products, etc. to end users. As an example, in a supply chain SC for delivering industrial products to consumers, the traders TR include a material supplier, a parts supplier TR1, an assembly supplier TR2, and a finished product manufacturer TR3.

[0017] The distribution management system 110 collects transaction records of transaction items between traders TR using a public code CdP. The distribution management system 110 is composed of an input terminal 11, a laser processing machine 12, a code reader 13, a system server 10, etc. The input terminal 11, the laser processing machine 12, and the code reader 13 are appropriately installed in the facilities of each trader TR. The input terminal 11, the laser processing machine 12, and the code reader 13 are connected via a network to the system server 10 installed in a data center or the like.

[0018] The input terminal 11 is, for example, a personal computer or a tablet terminal. Basic information (hereinafter referred to as item information) of a trade item supplied to the supply chain SC is input to the input terminal 11 in a predetermined format. For example, the item information may include the product name, place of production, production equipment, and manufacturer. The input terminal 11 transmits the item information of the trade item shipped from the trader TR to the system server 10.

[0019] The laser processing machine 12 is a laser marker device that engraves the disclosure code CdP on a trade item shipped from the trader TR. A fiber laser marker, a UV laser marker, a CO2 laser marker, or the like can be used as the laser processing machine 12. The disclosure code CdP is circulated together with the trade item after being engraved by the laser processing machine 12. The laser processing machine 12 may be capable of engraving the disclosure code CdP by laser marking on a marking part BM (see FIG. 1) made of various materials such as resin, metal, ceramic, paper, wood, glass, and rubber.

[0020] The trader TR, who attaches the printed disclosure code CdP to the trade item to be shipped, uses a label printer instead of the laser processing machine 12. The label printer is an output device for printing the disclosure code CdP on paper media. The label printer is configured to be capable of printing in color or grayscale. The paper media on which the disclosure code CdP is printed is affixed to the package or outer box of the trade item to be shipped, and is distributed as an attachment to the trade item.

[0021] The code reader 13 is a reading device that reads the public code CdP to obtain the public information recorded in the public code CdP. The code reader 13 obtains the public information recorded in the public code CdP and transmits the obtained public information to the system server 10.

[0022] The system server 10 is a host node capable of communicating with the input terminal 11, the laser processing machine 12, and the code reader 13. The system server 10 registers item information acquired from the input terminal 11 in a database. The system server 10 prepares public information linked to the item information and generates a public code CdP that records this public information. As part of the process of issuing the public code CdP, the system server 10 transmits image data, etc. of the generated public code CdP to the laser processing machine 12, which is the sender of the item information. When the issued public code CdP is circulated together with the transaction item and is read by the code reader 13 of another transactor TR, the system server 10 accumulates a transaction record of the transaction item by this transactor TR.

[0023] The traceability system 120 is used in conjunction with the distribution management system 110, and accumulates transaction records in the same way as the distribution management system 110. In other words, the distribution management system 110 corresponds to the old management system, and the traceability system 120 corresponds to the new management system. The traceability system 120 is operated together with the existing distribution management system 110 without making any substantial changes to the distribution management system 110. In addition to a record generation function that accumulates transaction records using the secret code CdS, the traceability system 120 also has a record reference function that makes the accumulated transaction records available for reference. The traceability system 120 uses blockchain technology to manage transaction records in order to prevent tampering with the transaction records.

[0024] The traceability system 120 is composed of a code reader 23, an ultraviolet light source 24, a history management server 20, etc. Furthermore, the traceability system 120 uses an input terminal 11 and a laser processing machine 12 of the distribution management system 110. The code reader 23 and the input terminal 11 are connected via a network to the history management server 20 installed in a data center or the like.

[0025] The code reader 23 and ultraviolet light source 24 are installed at the facility of the trader TR (such as assembly supplier TR2) to which trade items stamped with the concealment code CdS are delivered. The code reader 23 is a reading device that reads the confidential information recorded in the concealment code CdS. Since the code reader 23 is configured to scan the same object (stamped part BM, see FIG. 1 ) as the code reader 13, it may be physically integrated with the code reader 13. In other words, the code reader 13 of the distribution management system 110 may also be used in the traceability system 120.

[0026] The code reader 23 is composed of an imaging sensor formed by a two-dimensional array of CCD elements, a signal processing unit 41, etc. The imaging sensor outputs an image (hereinafter referred to as a code image) showing the concealment code CdS to the signal processing unit 41. The signal processing unit 41 has a memory unit that stores a code reading program, etc., a processor that executes code reading processing based on the code reading program, and a RAM. The signal processing unit 41 decodes the read signal (code image) of the imaging sensor according to predetermined rules through code reading processing, and acquires the confidential information recorded in the concealment code CdS. Based on the acquired confidential information, the signal processing unit 41 communicates with the history management server 20 to leave a transaction record.

[0027] Note that a smartphone, tablet terminal, or the like having a camera function may be used as the code reader 23. In such a case, a dedicated application equivalent to a code reading program (hereinafter referred to as a code reading app) is provided and installed on the smartphone, etc. The code reading app may be capable of reading the public code CdP in addition to reading the confidential code CdS.

[0028] The ultraviolet light source 24 irradiates the marking part BM (see FIG. 1) with invisible ultraviolet light when the code reader 23 reads the concealment code CdS. The ultraviolet light source 24 has multiple ultraviolet LEDs and emits ultraviolet light in a wavelength band of 300 to 380 nm (for example, a wavelength of 375 nm). The irradiation of ultraviolet light by the ultraviolet light source 24 enables the code reader 23 to photograph the concealment code CdS.

[0029] The history management server 20 is a host node that can communicate with the input terminal 11 and the laser processing machine 12 in addition to the code reader 23. The history management server 20 is mainly configured as a computer that includes a processing unit 31, RAM 32, a storage unit 33, an input / output interface, and a bus connecting these. The processing unit 31 is hardware for arithmetic processing that is coupled to the RAM 32. The processing unit 31 accesses the RAM 32 to execute various processes related to data management. The storage unit 33 stores management programs and the like related to data management.

[0030] The history management server 20 acquires item information sent from the input terminal 11 to the system server 10. Based on the acquired item information, the history management server 20 generates a blockchain linked to the traded item, which stores the item information and trade records. When the history management server 20 acquires a notification from the code reader 23 of each trader TR that the confidentiality code CdS has been read, the history management server 20 accumulates the trade record of the trader TR that sent the notification in the blockchain linked to the traded item.

[0031] When the history management server 20 receives a notification from the code reader 23, it generates a new block to store transaction records, etc., of the trader TR that sent the notification. The new block contains the current transaction record as well as a hash value calculated from the previous block. A hash function such as SHA-256 is used to generate the hash value. The history management server 20 generates a hash value with a number of bits that is fewer than the amount of data that can be recorded in the confidentiality code CdS. The hash value is data that maintains a predetermined number of bits (e.g., 256 bits) and reflects item information and transaction records.

[0032] The history management server 20 generates a confidentiality code CdS that records at least the above-mentioned hash value as confidential information. The history management server 20 issues the generated confidentiality code CdS to the laser processing machine 12. The laser processing machine 12 engraves the confidentiality code CdS, for example, in a position adjacent to the public code CdP. As a result, a hash value reflecting the item information and transaction record is recorded in the confidentiality code CdS, making it possible to circulate it together with the transaction item.

[0033] In the traceability system 120, a single concealment code CdS may be continuously used across multiple traders TR, or a new concealment code CdS may be issued for each trader TR. In a configuration in which a new concealment code CdS is issued for each trader TR, a new hash value reflecting a transaction record is generated based on the occurrence of a transaction record at each trader TR. The history management server 20 generates a new concealment code CdS recording the new hash value as concealment information, and provides the new concealment code CdS data to the laser processing machine 12 at the facility of the trader TR that conducted the transaction. As a result, as the transaction of an item progresses, the content (hash value) of the concealment code CdS is continually updated to reflect the transaction record up to that point. Furthermore, because the concealment information is primarily based on hash values, the data volume of the concealment information can be maintained constant even as the transaction of items progresses in the supply chain SC.

[0034] The history management server 20 can further issue a tracing code QRt. The tracing code QRt is a two-dimensional code such as a QR code attached to the final product FP supplied by the supply chain SC. The tracing code QRt enables the consumer who has acquired the final product FP to check the transaction record. As an example, the tracing code QRt records a hash value calculated from the last block of the blockchain and an IP address or URL indicating the contact point for inquiries about the transaction record.

[0035] A consumer of the final product FP can view the transaction record of the final product FP by using a user terminal UT, such as a smartphone or tablet terminal, and a traceability confirmation app. Specifically, the user terminal UT reads the tracing code QRt attached to the final product FP and sends a transaction record reference request along with a hash value to the history management server 20, which is the contact point for inquiries. Upon receiving the reference request, the history management server 20 extracts the item information and transaction record linked to the hash value and generates data to be provided. The history management server 20 transmits the generated data to the user terminal UT, which is the source of the reference request. A consumer of the final product FP can use the traceability confirmation app to open the data to be provided received from the history management server 20 and check the history of the transaction record.

[0036] <Secrecy code generation process> Next, the details of the code forming method of the present disclosure for forming a concealment code CdS on a stamped part BM will be further described based on the code forming process shown in Fig. 3 and with reference to Fig. 1 and Fig. 2. In the code forming process, a part preparation step S10, a cleaning step S20, a coating agent preparation step S30, a masking step S40, a light-emitting layer formation step S50, and a laser engraving step S60 are carried out in this order.

[0037] In the component preparation process S10, a stamped component BM is prepared, on which the concealment code CdS is to be engraved. In the cleaning process S20, at least the flat surface portion FA, which includes the formation area CA of the concealment code CdS, of the outer surface of the stamped component BM prepared in the component preparation process S10 is cleaned. In the cleaning process S20, for example, a non-water-soluble solvent is used to remove dirt such as oils, grease, and dust adhering to the flat surface portion FA.

[0038] In the coating agent preparation step S30, a coating agent to be applied to the flat surface FA of the stamped part BM is prepared. The coating agent is a reactive paint that emits light in response to invisible light and contains an ultraviolet-reactive paint that emits light in response to ultraviolet light. As an example, the coating agent is a colorless, transparent liquid product produced by mixing an ultraviolet-reactive paint, an acrylic clear paint, and a solvent such as thinner in a predetermined mixing ratio (e.g., 1:60:60). An example of the ultraviolet-reactive paint used in this embodiment is Superglow Fluorescent Leak Detection Agent (DF-300 Liquid) manufactured by MARKTEC. The ultraviolet-reactive paint contains 45 to 55 wt% water-soluble fluorescent paint and 45 to 55 wt% water.

[0039] In the masking step S40, the periphery of the formation area CA of the concealment code CdS is masked. The outer edge of the formation area CA corresponds to the outer edge of the quiet zone of the concealment code CdS. As an example, the area surrounded by the masking is set so that a margin of at least several millimeters is secured on all sides of the formation area CA.

[0040] In the light-emitting layer forming step S50, a coating agent is applied to the flat surface portion FA after the masking step S40. As a result, a colorless and transparent light-emitting layer 50 (see FIG. 1) is formed in an area that encompasses the formation area CA. To apply the coating agent, a coating device 25 such as a spray gun is used. The coating device 25 sprays the liquid coating agent prepared in the coating agent preparation step S30 onto the flat surface portion FA by injecting high-pressure air or gas. After spraying, a predetermined drying time (e.g., about 10 minutes) is ensured to dry the coating agent. In the light-emitting layer forming step S50, the process of applying the coating agent using the coating device 25 and the process of drying the applied coating agent are repeated multiple times (e.g., about three times). As a result of the above, the light-emitting layer 50 is formed as a coating film containing an ultraviolet-sensitive paint.

[0041] In the light-emitting layer forming step S50, the process of applying the coating agent containing the ultraviolet reactive paint may be performed by printing, stamping, or the like. In addition, the masking around the light-emitting layer 50 may be removed after the coating agent has dried in the light-emitting layer forming step S50, or may be removed after the laser engraving step S60. Furthermore, when the coating process and drying process are repeatedly performed, the light-emitting layer 50 is formed in a layered shape, like very thin coating films stacked on top of each other. Therefore, if multiple coating layers are formed, it can be considered that the coating process and drying process have been repeatedly performed.

[0042] In the laser engraving step S60, data of the concealment code CdS provided from the history management server 20 is prepared by the laser processing machine 12. In the laser engraving step S60, the concealment code CdS is engraved into the light emitting layer 50 by irradiating it with laser light by the laser processing machine 12. The laser processing machine 12 irradiates the light emitting layer 50 with laser light in the ultraviolet wavelength band (for example, a wavelength of 343 nm).

[0043] In the laser engraving process S60, laser light is irradiated onto the portions of the light-emitting layer 50 that correspond to the dark cells Ceb of the CdS secret code. On the other hand, laser light is not irradiated onto the portions of the light-emitting layer 50 that correspond to the light cells Cew. As a result, the light-emitting function of the portions that will become the dark cells Ceb is weakened relative to the light-emitting function of the portions that will become the light cells Cew. As a result, the portions of the light-emitting layer 50 that correspond to the light cells Cew become strong light-emitting portions 61, which emit strong light in response to ultraviolet light. On the other hand, the portions of the light-emitting layer 50 that correspond to the dark cells Ceb become weak light-emitting portions 62, which emit light that is darker than the strong light-emitting portions 61.

[0044] <Explanation of the mechanism that reduces the luminous function> Next, the principle by which ultraviolet reactive paint emits light and the mechanism by which this light-emitting function is reduced will be explained with reference to FIG.

[0045] UV-reactive paint contains a water-soluble fluorescent dye. This fluorescent paint emits a bluish-white fluorescent light when irradiated with ultraviolet light. The fluorescent dye excites electrons by absorbing the energy of ultraviolet light. The excited electrons become unstable and try to return to a stable ground state. When the electrons return to the ground state, they emit excess energy as electromagnetic waves. The wavelength of the emitted electromagnetic waves is longer than the wavelength of the irradiated ultraviolet light. As a result, when irradiated with ultraviolet light, the fluorescent dye enters a luminous state, emitting visible light with a longer wavelength than ultraviolet light.

[0046] The luminescence function of such fluorescent paint weakens when irradiated with laser light. Details of this will be explained using the results of the transmittance test shown in FIG. 4. In the transmittance test shown in FIG. 4, three measurement pieces were prepared. The first measurement piece was a measurement piece consisting of only a colorless, transparent, plate-shaped quartz plate 140 (hereinafter referred to as the reference measurement piece MSR). The second measurement piece was a measurement piece (hereinafter referred to as the first measurement piece MS1) in which a transparent coating film 141 containing no UV-sensitive paint was formed on one side of the quartz plate 140 by applying an acrylic clear coating. The third measurement piece was a measurement piece (hereinafter referred to as the second measurement piece MS2) in which a fluorescent coating film 142 containing UV-sensitive paint was formed on one side of the quartz plate 140 by applying a coating agent. The coating agent applied to the second measurement piece MS2 has the same components as the coating agent prepared in the coating agent preparation step S30 (see FIG. 3).

[0047] The reference measurement piece MSR, first measurement piece MS1, and second measurement piece MS2 are processed by irradiating them with laser light in the ultraviolet wavelength band (e.g., wavelength 343 nm), as in the laser engraving step S60 (see FIG. 3). For the reference measurement piece MSR, the transmittance before processing (pre-processing transmittance) is the same as the transmittance after irradiation with the laser light (post-processing transmittance). Similarly, for the first measurement piece MS1, the pre-processing transmittance and post-processing transmittance are the same.

[0048] On the other hand, for the second measurement piece MS2, the transmittance after processing (55%) is lower than the transmittance of the first measurement piece MS1 (92%), but is significantly higher than the transmittance before processing (38%). This increase in transmittance means that the amount of ultraviolet light energy absorbed by the fluorescent paint in the processed fluorescent coating 142 decreases. As a result, the number of excited electrons and, ultimately, the amount of energy released as electromagnetic waves also decreases, which is presumably why the light-emitting function of emitting visible light is diminished.

[0049] For these reasons, in the laser engraving step S60 (see FIG. 3) of the code formation process, the transmittance of ultraviolet light in the areas corresponding to the dark cells Ceb is made higher than the transmittance in the areas corresponding to the light cells Cew. As a result, it is possible to form weak light-emitting portions 62 in the areas corresponding to the dark cells Ceb, which have a weaker light-emitting function than the areas corresponding to the light cells Cew.

[0050] <Laser light output setting> The output of the laser light irradiated in the laser engraving step S60 (see FIG. 3) is set to a value that prevents discoloration of the surface of the light-emitting layer 50 and that can reduce the light-emitting function of the ultraviolet reactive paint. In the code forming method according to the present disclosure, whether the output of the laser light is set appropriately is quantitatively determined based on the surface condition and light-emitting state of the light-emitting layer 50 after the laser engraving step S60. Details of the indexes for determining whether the surface condition and light-emitting state of the light-emitting layer 50 are good or bad will be described below based on FIGS. 5 to 9 and with reference to FIGS. 1 and 2.

[0051] FIG. 5 shows the differences in the surface condition and light-emitting state of the light-emitting layer 50 in a test in which the laser output was changed in eight stages in the range of 0.08 W to 0.0033 W. In the test shown in FIG. 5, a measurement sample MS3 is used in which the light-emitting layer 50 is formed on a steel plate material 240 (e.g., SPCC, etc.) that has been given a matte black coating, as shown in FIG. 6. A plurality of test irradiation areas (e.g., 1 mm × 1 mm) provided on the measurement sample MS3 are irradiated with laser light under the conditions shown in FIG. 6, with the output power switched to each of the above-mentioned levels. FIG. 5 shows the appearance of each test irradiation area observed under the conditions shown in FIG. 7 using a microscope (VHX-7100) manufactured by KEYENCE Corporation.

[0052] [1. Indicators for determining the surface condition of the light-emitting layer] As shown in FIG. 5, if the output power of the laser beam irradiated in the laser engraving step S60 is too high, the light-emitting layer 50 will discolor (see laser outputs of 0.08 W and 0.04 W). In this case, the CdS concealment code will be easily visible without ultraviolet light irradiation. This discoloration of the light-emitting layer 50 is caused by the laser beam scraping the outer surface of the light-emitting layer 50. Therefore, in the laser engraving step S60, the output power of the laser beam is set so that the difference between the depth of the non-irradiated area 161 (not irradiated with laser light) and the depth of the irradiated area 162 (irradiated with laser light) (hereinafter referred to as the depth difference value) falls within a predetermined range. Specifically, the output power of the laser beam is set so that the depth difference value is preferably in the range of 0 to 1.0 μm, and more preferably in the range of 0 to 0.2 μm. For example, in the sample group shown in FIG. 5, a laser output power of 0.0133 W or less is a preferred setting range.

[0053] Here, the non-irradiated area 161 is an area corresponding to the strong light-emitting portion 61 and the light cell Cew. On the other hand, the irradiated area 162 is an area corresponding to the weak light-emitting portion 62 and the dark cell Ceb. Therefore, in the case of the concealment code CdS (see FIG. 1), if the outer surface of the light-emitting layer 50 is taken as a reference plane, the difference in depth from the reference plane between the strong light-emitting portion 61 and the weak light-emitting portion 62 is the depth difference value. As described above, the depth difference value is preferably in the range of 0 to 1.0 μm, and more preferably in the range of 0 to 0.2 μm.

[0054] The depths of the non-irradiated area 161 (strong light-emitting area 61) and the irradiated area 162 (weak light-emitting area 62) are measured using, for example, a white light interferometer (Nexview) from ZYGO under the conditions shown in Fig. 8. The depth measurement is performed, for example, on the vicinity of the center of one cell Ce (see Fig. 1). As an example, the average value of the depth values ​​measured using multiple light-colored cells Cew is used as the depth value of the non-irradiated area 161 (strong light-emitting area 61), and the average value of the depth values ​​measured using multiple dark-colored cells Ceb is used as the depth value of the irradiated area 162 (weak light-emitting area 62).

[0055] The maximum, minimum or median of the depth values ​​measured in the plurality of light cells Cew may be set as the depth value of the non-illuminated area 161, and the maximum, minimum or median of the depth values ​​measured in the plurality of dark cells Ceb may be set as the depth value of the illuminated area 162. Furthermore, the depth values ​​measured in a specific light cell Cew and a specific dark cell Ceb may be set as depth values ​​representing the non-illuminated area 161 and the illuminated area 162, respectively.

[0056] In the test shown in Fig. 5, when the laser output was 0.02 W or 0.0167 W, the depth of the irradiation range 162 changed significantly in some areas. This was caused by the fact that the processing threshold of the black painted part of the steel plate material 240 was lower than the processing threshold of the ultraviolet reactive paint.

[0057] Specifically, a laser beam output of 0.04 W or more exceeds the processing threshold of the ultraviolet-sensitive paint. Therefore, when the laser output is 0.08 W or 0.04 W, the laser beam output decreases due to processing of the ultraviolet-sensitive paint, and no processing occurs in the black-painted portion of the steel plate material 240. On the other hand, a laser beam output of 0.0133 W or less falls below the processing thresholds of both the ultraviolet-sensitive paint and the black-painted portion. Therefore, when the laser output is 0.0133, 0.01, 0.0067, or 0.0033 W, the laser beam penetrates the light-emitting layer 50 and reaches the black-painted portion, but does not process the black-painted portion.

[0058] In contrast, a laser beam output of 0.02 W or 0.0167 W does not exceed the processing threshold of the ultraviolet-sensitive paint, but does exceed the processing threshold of the black painted portion. Therefore, when the laser output is 0.02 W or 0.0167 W, the laser beam penetrates the light-emitting layer 50 and reaches the black painted portion, processing a portion of the black painted portion and causing evaporation or impact in the black painted portion where the laser beam reached. This presses the upper light-emitting layer 50 covering the black painted portion, causing a localized rise in the light-emitting layer 50. For these reasons, it is preferable that the laser beam output be appropriately adjusted according to the physical properties of the flat portion FA (see FIG. 1 ), and be set to a value that satisfies the above-mentioned processing depth condition and does not exceed the processing threshold of the flat portion FA.

[0059] [2. Indicators for determining the luminescence state when irradiated with ultraviolet light] As shown in Figure 5, if the output of the laser light irradiated in the laser engraving step S60 is insufficient, the light-emitting function will not be sufficiently reduced (see laser outputs of 0.0067W and 0.0033W). In this case, even if ultraviolet light is irradiated, it will be difficult to read the CdS secret code. To avoid this situation, in the laser engraving step S60, the output of the laser light is set so that the value obtained by subtracting the color intensity of the irradiated area 162 from the color intensity of the non-irradiated area 161 (hereinafter referred to as the color intensity difference value) falls within a predetermined range.

[0060] Here, the definition of the color intensity will be explained. The color intensity is a value indicating the color in a converted image obtained by converting a captured image of the light-emitting layer 50 (hereinafter referred to as an intensity measurement image) into a grayscale image, with a value corresponding to black being 1 and a value corresponding to white being 100. The color intensity corresponds to a value indicating the luminance of light emitted when irradiated with ultraviolet light, with the value increasing as the area emits light with higher luminance and decreasing as the area emits light with lower luminance. The color intensity is measured under the conditions shown in FIG. 9 using a black light manufactured by Ohm Electric Co., Ltd., a camera manufactured by Panasonic Corporation, image processing software manufactured by Adobe Systems Incorporated, and the like.

[0061] To measure color intensity, a full-color intensity measurement image is first generated by irradiating ultraviolet light using a black light and photographing the luminescent layer 50 (concealment code CdS) with a camera. This intensity measurement image is then converted to grayscale using image processing software. In the converted grayscale image, each pixel retains only brightness information. The brightness value (gradation value) of each pixel, expressed as a percentage, is the color intensity.

[0062] In the laser engraving step S60, the output power of the laser light is set so that the color intensity difference value is preferably 30 or greater, and more preferably 35 or greater. For example, in the sample group shown in FIG. 5, a laser output range of 0.0133 W or greater is the preferred setting range. Similarly, with the concealment code CdS (see FIG. 1), the color intensity difference value is calculated by subtracting the color intensity of the weak light emitting portion 62 from the color intensity of the strong light emitting portion 61. As mentioned above, the color intensity difference value is preferably 30 or greater, and more preferably 35 or greater.

[0063] In the above color intensity measurements, the average gradation value of the group of pixels capturing the center of one cell Ce (see Figure 1), specifically the central 0.8 mm square area of ​​the 1 mm square cell Ce, is taken as the color intensity of that cell Ce. The color intensity of multiple light cells Cew is then averaged to determine the color intensity value of the non-illuminated area 161 (strong light emission area 61), and the color intensity of multiple dark cells Ceb is taken as the color intensity value of the illuminated area 162 (weak light emission area 62).

[0064] The maximum, minimum or median value of the color intensities of the multiple light cells Cew may be set as a value indicating the color intensity of the non-illuminated area 161, and the maximum, minimum or median value of the color intensities of the multiple dark cells Ceb may be set as a value indicating the color intensity of the illuminated area 162. Furthermore, the color intensity values ​​of a specific light cell Cew and a specific dark cell Ceb may be set as color intensity values ​​representing the non-illuminated area 161 and the illuminated area 162, respectively.

[0065] <Summary of the embodiment> In the embodiment described so far, the light-emitting function of the portions of the light-emitting layer 50 containing ultraviolet reactive paint that correspond to the dark cells Ceb is weakened compared to the portions that correspond to the light cells Cew. Therefore, irradiation with invisible ultraviolet light reveals an arrangement of the dark cells Ceb and the light cells Cew with different light-emitting intensities. As a result, a special reading device (code reader 23) is not required to read the concealment code CdS, ensuring the convenience of the concealment code CdS.

[0066] Additionally, in this embodiment, the luminescent layer 50 is formed over the entire area including the formation area CA, and individual dark cells Ceb are formed in this integrated luminescent layer 50. Therefore, the durability of the coating film is more easily ensured than in a configuration in which fine coating films are individually formed in areas corresponding to the dark cells Ceb. As a result, it is possible to engrave a persistent concealment code CdS on the engraved part BM, which is used in a variety of environments. As a result, the convenience of the concealment code CdS can be further improved.

[0067] Furthermore, in this embodiment, the dark cells Ceb are engraved with a laser, and compared to a form in which the dark cells Ceb are printed, it is possible to achieve a higher resolution of the concealment code CdS while ensuring durability. Therefore, it is possible to reduce the size of the formation area CA of the concealment code CdS while ensuring the amount of recordable information. This makes it possible to engrave the concealment code CdS on a narrow flat surface portion FA, further improving the convenience of the concealment code CdS.

[0068] Furthermore, in this embodiment, in the laser engraving step S60, in which laser light is irradiated, the invisible light transmittance of the area corresponding to the dark cell Ceb is made higher than the transmittance of the area corresponding to the light cell Cew. As a result, the energy absorbed by the fluorescent paint is reduced, and the luminous function of the area corresponding to the dark cell Ceb is reliably reduced. As a result, the brightness difference between the light cell Cew and the dark cell Ceb when irradiated with ultraviolet light is increased, making it even easier to read the secret code CdS.

[0069] Additionally, in the laser engraving step S60 of this embodiment, the output of the laser light is set so as not to discolor the light-emitting layer 50. As a result, it is possible to prevent the concealment code CdS from being recognized when not irradiated with ultraviolet light. As a result, it is possible to provide a highly concealable concealment code CdS.

[0070] Specifically, in this embodiment, the output of the laser light is set so that the difference in depth between the non-irradiated area 161, where the laser light is not irradiated, and the irradiated area 162, where the laser light is irradiated, is in the range of 0 to 1.0 μm, more preferably 0 to 0.2 μm. In other words, in the concealment code CdS, the difference in depth from the reference plane between the strong light emitting portion 61 and the weak light emitting portion 62 is preferably in the range of 0 to 1.0 μm, more preferably 0 to 0.2 μm. By setting the range of the depth difference value in this way, the concealment of the concealment code CdS can be more reliably ensured.

[0071] In addition, in the laser engraving step S60 of this embodiment, the output of the laser light is set so as to reduce the light-emitting function of the ultraviolet reactive paint. As a result, the light-emitting function of the area corresponding to the dark cell Ceb is reliably weakened, making it possible to ensure a difference in brightness between the light cell Cew and the dark cell Ceb when irradiated with ultraviolet light. Therefore, it becomes even easier to read the concealment code CdS when irradiated with ultraviolet light.

[0072] Specifically, in this embodiment, a value corresponding to black is defined as 1, a value corresponding to white is defined as 100, and a captured image of the light-emitting layer 50 is converted to a grayscale image. The color value in the grayscale converted image is defined as color intensity. Furthermore, in the laser engraving step S60, the output of the laser light is set so that the value obtained by subtracting the color intensity of the irradiated area 162 irradiated with the laser light from the color intensity of the non-irradiated area 161 is 30 or more, and more preferably 35 or more. In other words, in the concealment code CdS, the value obtained by subtracting the color intensity of the weak light-emitting area 62 from the color intensity of the strong light-emitting portion 61 is preferably 30 or more, and more preferably 35 or more. By setting the range of the color intensity difference value in this way, the readability of the concealment code CdS when irradiated with ultraviolet light can be further ensured.

[0073] Furthermore, in the light-emitting layer forming step S50 of this embodiment, the process of applying a coating agent and the process of drying the applied coating agent are repeated multiple times. Therefore, the thickness of the coating film formed as the light-emitting layer 50 can be ensured sufficiently. As a result, irradiation with ultraviolet light enables the light cell Cew to emit light with higher brightness. This increases the difference in brightness between the light cell Cew and the dark cell Ceb when irradiated with ultraviolet light, making it easier to read the secret code CdS.

[0074] In the above embodiment, the confidentiality code CdS corresponds to the "information code", the light cell Cew corresponds to the "light area", the dark cell Ceb corresponds to the "dark area", and the stamping part BM corresponds to the "forming object".

[0075] (Other embodiments) The above describes one embodiment of the present disclosure, but the present disclosure should not be construed as being limited to the above embodiment, and can be applied to various embodiments and combinations within the scope that does not deviate from the gist of the present disclosure.

[0076] In the first modification of the above embodiment, a concealment code CdS is engraved on the stamped part BM instead of the public code CdP. That is, two concealment codes CdS are formed side by side on one stamped part BM. One of the public codes CdP is an information code used in the distribution management system 110. According to the first modification described above, it is possible to record public information without impairing the design of the stamped part BM.

[0077] In the second modification of the above embodiment, the concealment code CdS is formed overlapping the disclosure code CdP. That is, after the disclosure code CdP is laser engraved on the engraved part BM, a transparent luminescent layer 50 is formed in a manner that covers the disclosure code CdP. Then, the disclosure code CdP is laser engraved on the luminescent layer 50 that covers the disclosure code CdP. In the second modification described above, it is possible to grasp the formation position of the invisible concealment code CdS by using the position of the visible disclosure code CdP as a clue.

[0078] In a third modification of the above embodiment, instead of the hash value, a unique identification (UID) that identifies the item shipped from the trader TR is recorded in the concealment code CdS as confidential information. As in this third modification, the confidential information recorded in the concealment code CdS may be changed as appropriate.

[0079] Furthermore, the use of the concealment code CdS is not limited to the management of the supply chain SC in the traceability system 120, but may be used by a system different from the traceability system 120. In this case, the concealment code CdS may be used alone without being combined with the public code CdP. As described above, the concealment code CdS according to the present disclosure is an information code that is particularly suitable for various applications that require recording information without making the marking noticeable.

[0080] In the concealment code CdS according to the fourth modification of the above embodiment, infrared light is used as the invisible light instead of ultraviolet light. That is, the coating agent used in the light-emitting layer contains a fluorescent paint that emits visible light when irradiated with infrared light. Then, in the laser marking step S60 (see FIG. 3), the light-emitting function of the light-emitting layer is weakened by the marking with the laser light. Furthermore, an infrared light source is used to read the concealment code CdS instead of the ultraviolet light source 24 (see FIG. 2).

[0081] In Modification 5 of the above embodiment, the repetition of the process of applying a coating agent and the process of drying the applied coating agent is omitted. As in Modification 5, as long as the luminescence brightness of the light-emitting layer 50 when irradiated with invisible light can be sufficiently ensured, the details of the light-emitting layer forming step S50 may be appropriately changed. Furthermore, the mixing ratio of the coating agent may also be appropriately changed.

[0082] In Modification 6 of the above embodiment, the public code CdP and the concealment code CdS are different versions from each other. Furthermore, in Modification 7 of the above embodiment, the public code CdP and the concealment code CdS are different sizes from each other. That is, the concealment code CdS may be a QR code larger than the public code CdP, or may be a QR code smaller than the public code CdP. Furthermore, in Modification 8 of the above embodiment, the public code CdP and the concealment code CdS are different versions from each other (number of cells). That is, the version of the concealment code CdS may be larger than the public code CdP, or may be smaller than the public code CdP. As in Modifications 6 to 8, the specifications of the public code CdP and the concealment code CdS may be changed as appropriate.

[0083] Furthermore, the two-dimensional codes used as the public code CdP and the confidentiality code CdS are not limited to QR codes. Two-dimensional codes different from QR codes may be used for the public code CdP and the confidentiality code CdS. Furthermore, the public code CdP and the confidentiality code CdS may be two-dimensional codes or one-dimensional codes based on mutually different standards.

[0084] In the above embodiment, the black cells of the original data of the two-dimensional code are linked to the dark cells Ceb of the concealment code CdS to be laser engraved, and the white cells of the original data are linked to the light cells Cew to be laser engraved. In contrast, in Modification 9 of the above embodiment, the linkage between the black and white cells of the original data and the engraved dark cells Ceb and light cells Cew is reversed. That is, the black cells of the original data are engraved as light cells Cew, and the white cells of the original data are engraved as dark cells Ceb.

[0085] In the above embodiment, a tracing code QRt is issued and attached to the final product FP in addition to the confidentiality code CdS used in the supply chain SC. However, the public code CdP may be registered in the history management server 20 and used as the tracing code QRt. Furthermore, the final product FP supplied by the supply chain SC may be changed as appropriate. For example, various items such as automobiles, batteries, semiconductors, fresh produce, seafood, food, flowers, pharmaceuticals, and chemicals can be managed by the traceability system 120.

[0086] The hash function used by the history management server 20 is a cryptographic hash function, which has the property that it never outputs the same hash value from different inputs and that it is virtually impossible to guess the input from the output hash value. For example, instead of the above-mentioned SHA-256, encryption algorithms such as SHA-1, SHA-2, and SHA-3 may be used as appropriate in accordance with the output length (number of bits) that can be recorded in the confidentiality code CdS as confidential information. Furthermore, the code generation process performed by the history management server 20 may be performed in the control circuit of the laser processing machine 12 on the edge side.

[0087] In the above embodiment, the functions provided by the history management server, code reader, etc. can be provided by software and hardware that executes it, software only, hardware only, or a combination of these. When such functions are provided by electronic circuits as hardware, each function can also be provided by digital circuits including multiple logic circuits, or analog circuits.

[0088] The processing unit (signal processing unit) in the above embodiment may be configured to include at least one arithmetic core such as a CPU (Central Processing Unit) and a GPU (Graphics Processing Unit).Furthermore, the processing unit may be configured to further include an FPGA (Field-Programmable Gate Array), an NPU (Neural network Processing Unit), an IP core with other dedicated functions, etc.

[0089] The form of the storage medium (non-transitory tangible storage medium) employed as each storage unit in the above embodiments and storing each program may be changed as appropriate. For example, the storage medium is not limited to a configuration provided on a circuit board, but may be provided in the form of a memory card or the like, inserted into a slot, and electrically connected to a computer bus. Furthermore, the storage medium may be an optical disk, a hard disk drive, or the like used as a source of copying or distributing programs to a computer.

[0090] The controller and methods described herein may be implemented by a special-purpose computer comprising a processor programmed to perform one or more functions embodied in a computer program. Alternatively, the apparatus and methods described herein may be implemented by special-purpose hardware logic circuitry. Alternatively, the apparatus and methods described herein may be implemented by one or more special-purpose computers comprising a processor executing a computer program in combination with one or more hardware logic circuits. Furthermore, the computer program may be stored as instructions executed by a computer on a computer-readable non-transitory storage medium.

[0091] (Disclosure of technical ideas) This specification discloses multiple technical ideas described in the following multiple clauses. Some clauses may be written in a multiple dependent form, with the subsequent clause referring to the preceding clause as an alternative. Furthermore, some clauses may be written in a multiple dependent form, referring to another multiple dependent clause. These multiple dependent clauses define multiple technical ideas.

[0092] (Technical thought 1) A code forming method for forming an information code (CdS) on a recording target (BM) by arranging a light color area (Cew) and a dark color area (Ceb), A light-emitting layer (50) including the information code formation area (CA) is formed by applying a coating agent containing a reactive coating material that emits light in response to invisible light to the formation object (S50); Irradiating a laser beam onto a portion of the light-emitting layer corresponding to the dark region weakens the light-emitting function of the dark region compared to the light region (S60). A cord forming method comprising the steps of: (Technical thought 2) A code forming method described in Technical Idea 1, in which in the process of irradiating laser light, the transmittance of the invisible light in the area corresponding to the dark color area is made higher than the transmittance in the area corresponding to the light color area. (Technical Thought 3) The code forming method according to Technical Idea 1 or 2, wherein in the step of irradiating the laser light, the output of the laser light is set so as not to discolor the light-emitting layer. (Technical Thought 4) A code forming method according to any one of Technical Ideas 1 to 3, wherein in the step of irradiating the laser light, the output of the laser light is set so that the difference in depth between the non-irradiated area (161) to which the laser light is not irradiated and the irradiated area (162) to which the laser light is irradiated is in the range of 0 to 1.0 μm. (Technical Thought 5) A code forming method according to any one of Technical Ideas 1 to 3, wherein in the step of irradiating the laser light, the output of the laser light is set so that the difference in depth between the non-irradiated area (161) to which the laser light is not irradiated and the irradiated area (162) to which the laser light is irradiated is in the range of 0 to 0.2 μm. (Technical Thought 6) A code forming method according to any one of Technical Ideas 1 to 5, wherein in the step of irradiating the laser light, the output of the laser light is set so as to reduce the light-emitting function of the reactive paint. (Technical Thought 7) When a value corresponding to black is set to 1 and a value corresponding to white is set to 100, the color value in a converted image obtained by converting a captured image of the light-emitting layer into a grayscale image is defined as color intensity. A code forming method described in any one of Technical Ideas 1 to 6, wherein in the step of irradiating the laser light, the output of the laser light is set so that the value obtained by subtracting the color intensity of the non-irradiated area (161) where the laser light is not irradiated from the color intensity of the irradiated area (162) where the laser light is irradiated is 30 or more. (Technical Thought 8) When a value corresponding to black is set to 1 and a value corresponding to white is set to 100, the color value in a converted image obtained by converting a captured image of the light-emitting layer into a grayscale image is defined as color intensity. A code forming method described in any one of Technical Ideas 1 to 6, wherein in the step of irradiating the laser light, the output of the laser light is set so that the value obtained by subtracting the color intensity of the non-irradiated area (161) where the laser light is not irradiated from the color intensity of the irradiated area (162) where the laser light is irradiated is 35 or more. (Technical Thought 9) A code forming method described in any one of Technical Ideas 1 to 8, in which in the process of forming the light-emitting layer, the process of applying the coating agent and the process of drying the applied coating agent are repeated multiple times. (Technical Thought 10) An information code that records information by arranging light color areas (Cew) and dark color areas (Ceb), a luminescent layer (50) containing a reactive paint that emits light in response to invisible light; a strong light emitting section (61) that is located in a portion of the light emitting layer that corresponds to the bright color region and that emits light in response to the invisible light; a weak light-emitting portion (62) located in a portion of the light-emitting layer corresponding to the dark color region, the weak light-emitting portion having a weaker light-emitting function of the reactive paint than the strong light-emitting portion; An information code comprising: (Technical Thought 11) When the outer surface of the light-emitting layer is taken as a reference plane, The information code according to Technical Idea 10, wherein the difference in depth from the reference surface between the strong light emitting portion and the weak light emitting portion is in the range of 0 to 1.0 μm. (Technical Thought 12) When the outer surface of the light-emitting layer is taken as a reference plane, The information code according to Technical Idea 10, wherein the difference in depth from the reference surface between the strong light emitting portion and the weak light emitting portion is in the range of 0 to 0.2 μm. (Technical Thought 13) When a value corresponding to black is set to 1 and a value corresponding to white is set to 100, the color value in a converted image obtained by converting a captured image of the light-emitting layer into a grayscale image is defined as color intensity. The information code according to any one of Technical Ideas 10 to 12, wherein a value obtained by subtracting the color intensity of the weak light emitting portion from the color intensity of the strong light emitting portion is 30 or more. (Technical Thought 14) When a value corresponding to black is set to 1 and a value corresponding to white is set to 100, the color value in a converted image obtained by converting a captured image of the light-emitting layer into a grayscale image is defined as color intensity. The information code according to any one of Technical Ideas 10 to 12, wherein a value obtained by subtracting the color intensity of the weak light emitting portion from the color intensity of the strong light emitting portion is 35 or more. [Explanation of symbols]

[0093] 50 luminescent layer, 61 strong luminescent part, 62 weak luminescent part, 161 non-irradiated area, 162 irradiated area, BM engraved part (forming target), CA forming area, CdS concealment code (information code), Ceb dark cell (dark area), Cew light cell (light area), S50 luminescent layer forming process, S60 laser engraving process

Claims

1. A code forming method for forming an information code (CdS) on a forming target (BM) by arranging light color areas (Cew) and dark color areas (Ceb), the method comprising: A coating agent containing a reactive coating material that emits light in response to invisible light is applied to the object to form a light-emitting layer (50) that encompasses the area (CA) where the information code is to be formed (S50); By irradiating a laser beam onto a portion of the light-emitting layer corresponding to the dark color region, the transmittance of the invisible light of the light-emitting layer at the portion corresponding to the dark color region is made higher than the transmittance of the light-emitting layer at the portion corresponding to the light color region, thereby weakening the light-emitting function of the dark color region compared to the light color region (S60). A cord forming method comprising the steps of:

2. 2. The code forming method according to claim 1, wherein in the step of irradiating the laser light, the output of the laser light is set so as not to discolor the light-emitting layer.

3. 2. The code forming method according to claim 1, wherein in the step of irradiating the laser light, the output of the laser light is set so that the difference in depth between the non-irradiated area (161) to which the laser light is not irradiated and the irradiated area (162) to which the laser light is irradiated is in the range of 0 to 1.0 μm.

4. 2. The code forming method according to claim 1, wherein in the step of irradiating the laser light, the output of the laser light is set so that the difference in depth between the non-irradiated area (161) to which the laser light is not irradiated and the irradiated area (162) to which the laser light is irradiated is in the range of 0 to 0.2 μm.

5. The code forming method according to any one of claims 1 to 4, wherein in the step of irradiating the laser light, the output of the laser light is set so as to reduce the light-emitting function of the reactive paint.

6. When a value corresponding to black is set to 1 and a value corresponding to white is set to 100, the color value in a converted image obtained by converting a captured image of the light-emitting layer into a grayscale image is defined as color intensity.

5. A code forming method according to claim 1, wherein in the step of irradiating the laser light, the output of the laser light is set so that the value obtained by subtracting the color intensity of the irradiated area (162) irradiated with the laser light from the color intensity of the non-irradiated area (161) not irradiated with the laser light is 30 or more.

7. When a value corresponding to black is set to 1 and a value corresponding to white is set to 100, the color value in a converted image obtained by converting a captured image of the light-emitting layer into a grayscale image is defined as color intensity.

5. A code forming method according to claim 1, wherein in the step of irradiating the laser light, the output of the laser light is set so that the value obtained by subtracting the color intensity of the irradiated area (162) irradiated with the laser light from the color intensity of the non-irradiated area (161) not irradiated with the laser light is 35 or more.

8. 2. The code forming method according to claim 1, wherein in the step of forming the light-emitting layer, the process of applying the coating agent and the process of drying the applied coating agent are repeated multiple times.

9. An information code that records information by an arrangement of light color areas (Cew) and dark color areas (Ceb), a light-emitting layer (50) containing a reactive paint that emits light in response to invisible light; a strong light emitting section (61) that is located in a portion of the light emitting layer that corresponds to the bright color region and that emits light in response to the invisible light; a weak light-emitting portion (62) located in a portion of the light-emitting layer corresponding to the dark color region, the weak light-emitting portion having a weaker light-emitting function of the reactive paint than the strong light-emitting portion; An information code comprising:

10. When the outer surface of the light-emitting layer is taken as a reference plane, 10. The information code according to claim 9, wherein the difference in depth from the reference surface between the strong light emitting portion and the weak light emitting portion is in the range of 0 to 1.0 μm.

11. When the outer surface of the light-emitting layer is taken as a reference plane, 10. The information code according to claim 9, wherein the difference in depth from the reference surface between the strong light emitting portion and the weak light emitting portion is in the range of 0 to 0.2 μm.

12. When a value corresponding to black is set to 1 and a value corresponding to white is set to 100, the color value in a converted image obtained by converting a captured image of the light-emitting layer into a grayscale image is defined as color intensity. The information code according to any one of claims 9 to 11, wherein a value obtained by subtracting the color intensity of the weak light emitting portion from the color intensity of the strong light emitting portion is 30 or more.

13. When a value corresponding to black is set to 1 and a value corresponding to white is set to 100, the color value in a converted image obtained by converting a captured image of the light-emitting layer into a grayscale image is defined as color intensity. The information code according to any one of claims 9 to 11, wherein a value obtained by subtracting the color intensity of the weak light emitting portion from the color intensity of the strong light emitting portion is 35 or more.

Images