Printed materials and printing paper

Abstract

The present invention provides a configuration for anti-counterfeiting printed material in which a first two-dimensional code, which is easily readable under visible light illumination and difficult to read under near-infrared light illumination, and a second two-dimensional code, which is difficult to read under visible light illumination and easily readable under near-infrared light illumination, are formed to overlap, thereby enabling easier reading of the two-dimensional codes than in conventional configurations. [Solution] A filter layer 9 that attenuates visible light and / or near-infrared light is formed in the overlapping area of ​​the first two-dimensional code 3 and the second two-dimensional code 4. With this configuration, when reading one of the two-dimensional codes 3 and 4, the contrast of the other two-dimensional code 3 and 4 that appears in the captured image is reduced, making it easier to read the two-dimensional codes 3 and 4 compared to the conventional configuration.

Description

Technical Field

[0001] The present invention relates to printed matter that requires anti-counterfeiting and printing paper for producing the printed matter.

Background Art

[0002] In order to prevent counterfeiting of printed matter such as tickets, there has been proposed a printed matter in which a two-dimensional code (visible code) that is easy to read under visible light illumination and difficult to read under near-infrared light illumination overlaps with a two-dimensional code (infrared code) that is difficult to read under visible light illumination and easy to read under near-infrared light illumination (see Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The printed matter according to Patent Document 1 above is configured to read the information of the visible code using an imaging image under visible light illumination and read the information of the infrared code using an imaging image under near-infrared light illumination. At this time, the pattern of the infrared code is reflected as noise in the imaging image under visible light illumination, and the pattern of the visible code is reflected as noise in the imaging image under near-infrared light illumination. Therefore, depending on the imaging conditions, during the process of identifying the brightness and darkness of the cells of the two-dimensional code, such noise may increase the identification error, resulting in failure to read the two-dimensional code or taking a long time.

[0005] The present invention has been made in view of such a situation, and an object thereof is to provide a printed matter in which a visible code and an infrared code formed to overlap each other can be read more easily than in the conventional configuration.

Means for Solving the Problems

[0006] A printed material is formed such that a first two-dimensional code, which is easily readable under visible light illumination and difficult to read under infrared light illumination in a predetermined band, and a second two-dimensional code, which is difficult to read under visible light illumination and easily readable under infrared light illumination in the predetermined band, overlap, wherein the printed material comprises a light-colored substrate with high reflectivity of infrared light in the predetermined band, the first two-dimensional code is printed in a dark color on the surface of the substrate, the second two-dimensional code is printed on the surface of the substrate with infrared light absorbing ink that has high absorption rate of infrared light in the predetermined band, and furthermore, a light-colored filter layer that attenuates visible light is formed on the surface of the substrate in the overlapping area of ​​the first two-dimensional code and the second two-dimensional code.

[0007] According to the inventor's research, this configuration makes it less likely for identification errors to occur when distinguishing the brightness of visible code cells. This is thought to be because the filter layer reduces the brightness of the background of the captured image, thereby lowering the contrast between the second two-dimensional code captured in the image and the background, and thus lowering the noise level. In this configuration, the filter layer also reduces the contrast between the first two-dimensional code and the background, but as long as the filter layer is not made excessively dark, it is possible to reliably distinguish the brightness of cells more reliably than in conventional configurations. According to the inventor's research, when the reflectance density of the substrate surface (OD value under white light illumination) is set to at least 0.1 to 0.4 by the filter layer, the frequency of identification errors when the reader distinguishes the brightness of visible code cells is suitably reduced.

[0008] In another aspect of the present invention, a printed material is proposed in which a first two-dimensional code that is easily readable under visible light illumination and difficult to read under infrared light illumination in a predetermined band and a second two-dimensional code that is difficult to read under visible light illumination and easily readable under infrared light illumination in the predetermined band are formed to overlap, wherein the printed material comprises a light-colored substrate with high reflectivity of infrared light in the predetermined band, the first two-dimensional code is printed in a dark color on the surface of the substrate, the second two-dimensional code is printed on the surface of the substrate with an infrared light absorbing ink that has high absorption rate of infrared light in the predetermined band, and furthermore, a filter layer that attenuates infrared light in the predetermined band is formed on the surface of the substrate in the overlapping area of ​​the first two-dimensional code and the second two-dimensional code.

[0009] According to the inventor's research, this configuration makes it less likely for identification errors to occur when distinguishing between the light and dark areas of the infrared code cells. This is thought to be because the filter layer reduces the reflectivity of infrared light of a predetermined wavelength in the background, thereby lowering the contrast between the first two-dimensional code captured in the image and the background. In this configuration, the filter layer also reduces the contrast between the second two-dimensional code and the background, but as long as the filter layer is not made excessively dark, it becomes possible to reliably distinguish between the light and dark areas of the cells compared to the conventional configuration.

[0010] In another aspect of the present invention, a printed material is proposed in which a first two-dimensional code, which is easily readable under visible light illumination and difficult to read under infrared light illumination in a predetermined band, and a second two-dimensional code, which is difficult to read under visible light illumination and easily readable under infrared light illumination in the predetermined band, are formed to overlap, wherein the printed material comprises a light-colored substrate with high reflectivity of infrared light in the predetermined band, the first two-dimensional code is printed in a dark color on the surface of the substrate, the second two-dimensional code is printed on the surface of the substrate with an infrared light absorbing ink that has high absorption rate of infrared light in the predetermined band, and furthermore, a light-colored filter layer that attenuates visible light and infrared light in the predetermined band is formed on the surface of the substrate in the overlapping area of ​​the first two-dimensional code and the second two-dimensional code. Such a filter layer is not limited to a single-layer structure, but may be a two-layer structure consisting of a layer that attenuates visible light and a layer that attenuates infrared light in the predetermined band.

[0011] With this configuration, errors in identification become less likely to occur in both the process of identifying the brightness of visible code cells and the process of identifying the brightness of infrared code cells.

[0012] In the present invention, it is proposed that the filter layer is uniformly formed in a region including the region where the first two-dimensional code is formed and the region where the second two-dimensional code is formed.

[0013] In this configuration, the brightness of the background of the captured image can be uniformly reduced, making it even less likely for identification errors to occur in the process of identifying the brightness of cells in a two-dimensional code.

[0014] Furthermore, in the above configuration, it is proposed that the filter layer is formed to cover the first two-dimensional code and the second two-dimensional code.

[0015] In this configuration, the surface irregularities of the formation areas of the first and second two-dimensional codes are reduced by the filter layer, making it less likely for light and dark areas based on surface irregularities to occur in the captured image. As a result, identification errors are further reduced in the process of identifying the light and dark areas of the two-dimensional code cells.

[0016] Furthermore, in the present invention, the filter layer is formed of a special ink with low absorption of infrared light in the predetermined band, and it is proposed that the filter layer and the infrared light absorbing ink layer are alternately arranged over the entire area of ​​the first two-dimensional code formation area and the second two-dimensional code formation area.

[0017] In this configuration, the printed area of ​​the infrared light-absorbing ink appears brighter than when a filter layer is superimposed on the printed area of ​​the infrared light-absorbing ink. This further reduces the contrast of the second two-dimensional code captured in the image under visible light illumination, thereby further lowering the noise level.

[0018] Furthermore, in the present invention, the first two-dimensional code and the second two-dimensional code are provided with a position detection pattern for optically detecting the position of each two-dimensional code, and the filter layer is formed so as to overlap at least the position detection pattern in the overlapping portion of the first two-dimensional code and the second two-dimensional code.

[0019] As in this configuration, forming the filter layer to overlap with the position detection pattern makes it less likely for problems to occur when reading the two-dimensional code. In two-dimensional codes such as QR codes, the cells that make up the position detection pattern are not subject to error correction, so if an error in light / dark discrimination occurs in the part of the position detection pattern, it is likely to cause problems when reading the two-dimensional code.

[0020] As another aspect of the present invention, there is provided printing paper for producing the printed matter of the present invention. The base material is thermal paper having a substantially white thermosensitive coloring layer formed on its surface. On the surface of the base material, the second two-dimensional code is pre-printed with the infrared light absorbing ink, and the filter layer is pre-formed at the formation site of the second two-dimensional code. The first two-dimensional code is configured to be thermosensitive printable at a position overlapping the second two-dimensional code. A printing paper characterized by this is proposed.

[0021] According to such printing paper, the printed matter of the present invention can be easily manufactured.

Effect of the Invention

[0022] As described above, according to the printed matter of the present invention, the visible code and the infrared code formed on the printed matter so as to overlap can be read more easily than in the conventional configuration. Also, according to the printing paper of the present invention, the printed matter of the present invention can be easily manufactured.

Brief Description of the Drawings

[0023] [Figure 1] (A) is a surface view of the anti-counterfeiting ticket 1 of Example 1 imaged under white light illumination. (B) is a surface view of the anti-counterfeiting ticket 1 of Example 1 imaged under near-infrared light illumination. [Figure 2] It is an exploded perspective view of the anti-counterfeiting ticket 1 of Example 1. [Figure 3] (A) is a surface view of the ticket issuing machine paper 30. (B) is a surface view of the anti-counterfeiting ticket 1 of Example 1. [Figure 4] (A) is an explanatory view showing an example of the visible code 3. (B) is an explanatory view showing the pattern division of each area of the visible code 3 according to its function. [Figure 5] (A) is an image of the two-dimensional code printing section 6 of Example 1 imaged under white light illumination. (B) is an image of the two-dimensional code printing section 6 of Example 1 imaged under near-infrared light illumination. [Figure 6](A) is an image of the two-dimensional code printing unit 6 of Example 2, taken under white light illumination. (B) is an image of the two-dimensional code printing unit 6 of Example 2, taken under near-infrared light illumination. [Figure 7] (A) is an image of the two-dimensional code printing unit 6 of Example 3, taken under white light illumination. (B) is an image of the two-dimensional code printing unit 6 of Example 3, taken under near-infrared light illumination. [Figure 8] This is an exploded perspective view of the anti-counterfeiting ticket 1a of Example 4. [Figure 9] (A) is an image of the two-dimensional code printing unit 6 of Example 1, taken under white light illumination. (B) is an image of the two-dimensional code printing unit 6 of Example 4, taken under white light illumination. [Figure 10] (A) is an image of the two-dimensional code printing unit 6 of Example 1, taken under white light illumination. (B) is an image of the two-dimensional code printing unit 6 of Example 5, taken under white light illumination. [Figure 11] This chart shows an overview of the comparative and test samples 1-9, as well as the results of the evaluation tests. [Modes for carrying out the invention]

[0024] Embodiments of the present invention will be described based on the following examples. In the following embodiments, the first two-dimensional code according to the present invention corresponds to a visible code 3, and the second two-dimensional code according to the present invention corresponds to an infrared code 4. Furthermore, the infrared light in a predetermined band according to the present invention corresponds to near-infrared light (particularly wavelengths of 750 nm to 900 nm). [Examples]

[0025] As shown in Figure 1(A), the printed material in this embodiment is a railway anti-counterfeiting ticket 1. On the anti-counterfeiting ticket 1, two-dimensional codes 3 and 4 are printed on the two-dimensional code printing area 6 on the front side of the base material 2 to verify the validity of the ticket. In addition, text information 5 indicating ticket information is printed on the parts other than the two-dimensional code printing area 6. Although not shown in the figure, the back side of the anti-counterfeiting ticket 1 is plain white.

[0026] As shown in Figure 1(A), two types of two-dimensional codes 3 and 4 are printed on the two-dimensional code printing unit 6 in an overlapping manner. One of the two-dimensional codes is a visible code 3 that records information based on the reflectivity pattern of visible light such as white light, making it easy to read under visible light illumination such as white light, but difficult to read under near-infrared light illumination. The other two-dimensional code is an infrared code 4 that records information based on the reflectivity pattern of near-infrared light, making it readable under near-infrared light illumination.

[0027] The base material 2 of the anti-counterfeiting ticket 1 is a plain white thermal paper made by coating the front surface of a paper base material body 21 with a heat-sensitive color-developing layer 20. As shown in Figure 2, the visible code 3 and character information 5 are formed by using a thermal printer to heat-develop the heat-sensitive color-developing layer 20 in the dark cell areas to create black. On the other hand, the infrared code 4 is formed by printing infrared light-absorbing ink 22, which has the property of absorbing near-infrared light, on top of the heat-sensitive color-developing layer 20 of the base material 2. In addition, a filter layer 9 is formed on the front surface of the base material 2 in a rectangular area including the entire two-dimensional code printing area 6. The filter layer 9 is uniformly solid-printed with a yellow-green special ink 23 on top of the infrared light-absorbing ink 22. Details of the filter layer 9 will be described later.

[0028] The infrared code 4 printed before issuance may contain common information used for authenticity verification. On the other hand, the visible code 3 printed at the time of issuance may contain variable information that differs for each ticket, such as the travel section and expiration date. Such an anti-counterfeiting ticket 1 can be efficiently issued by a printing company if, for example, as shown in Figure 3(A), a printing company manufactures a ticket machine paper 30 with only the infrared code 4 and filter layer 9 printed on it, and then, as shown in Figure 3(B), the ticket machine simply thermally prints the visible code 3 and text information 5 onto the ticket machine paper 30.

[0029] Visible Code 3 is a general QR code (registered trademark) that conforms to the standard (JIS X 0510). Here, the structure of a general QR code will be explained based on Visible Code 3. As shown in Figure 4(A), Visible Code (QR Code) 3 consists of square cells 10, which are colored either light (white) or dark (black), arranged in a matrix in both vertical and horizontal directions. As shown in Figure 4(B), Visible Code 3 is broadly divided into two areas: a functional pattern 7 and an encoding area 8.

[0030] Functional pattern 7 is an area where the color scheme pattern of cell 10 is predetermined, and is composed of a position detection pattern 11, a separation pattern 12, a timing pattern 13, an alignment pattern 14, etc., which assist in the optical reading of the visible code 3. The position detection pattern 11 is a concentric square pattern provided at the three corners of the visible code 3: the upper left corner, the lower left corner, and the upper right corner. This position detection pattern 11 allows the reading device to easily detect the visible code 3 from an image captured under visible light illumination such as white light. The separation pattern 12 is a pattern of light-colored cells 10 surrounding the position detection pattern 11, and this separation pattern 12 allows the position detection pattern 11 to be separated and identified from its surroundings. The timing pattern 13 is a pattern in which light-colored and dark-colored cells 10 appear alternately in one row each in the vertical and horizontal directions. This timing pattern 13 allows the center coordinates of each cell 10 to be identified in an image of the visible code 3. The alignment pattern 14 is a concentric square pattern located in the lower right corner of the visible code 3. This alignment pattern 14 makes it possible to correct the distortion of the visible code 3 in the captured image.

[0031] The encoding area 8 is an area that records data based on the color scheme pattern of cell 10, and consists of a data code area 15 for recording messages and a format information code area 16 for recording QR code format information and model number information. The information recorded in the encoding area 8 includes error correction codes, so that even if the brightness of cell 10 is slightly misidentified during the process of identifying the brightness of the cells in the two-dimensional code, the error can be corrected and the correct information can be decoded.

[0032] Infrared Code 4 is also a two-dimensional code that basically conforms to the QR code standard (JIS X 0510). However, while the common QR code, Visible Code 3, is composed of a pattern of 10 cells of light and dark colors, Infrared Code 4 is composed of a pattern of infrared reflective cells with high reflectivity to near-infrared light and infrared absorbing cells with low reflectivity to near-infrared light.

[0033] Infrared code 4 is formed by solid printing of infrared light absorbing ink 22 onto the infrared absorption cell portion. Infrared light absorbing ink 22 is a yellow-green ink that transmits the underlying color. As shown in Figure 5(A), under white light illumination, the areas where infrared light absorbing ink 22 is solid printed appear as a bright yellow-green (shown as gray in the figure) due to the mixing of the white of the substrate 2 and the yellow-green of the filter layer 9 in the areas that overlap with the uncolored areas of the heat-sensitive color-developing layer 20, and appear as black due to the mixing of the black of the substrate 2 and the yellow-green of the filter layer 9 in the areas that overlap with the colored areas of the heat-sensitive color-developing layer 20.

[0034] In the two-dimensional code printing section 6, the infrared code 4 (infrared light absorbing ink 22) and filter layer 9 (special ink 23) are printed on top of the visible code 3. However, as shown in Figure 5(A), under white light illumination, regardless of the presence or absence of the infrared light absorbing ink 22 and special ink 23, the black parts of the thermal coloring layer 20 (dark-colored cells of the visible code 3) appear dark (black), and the white parts of the thermal coloring layer 20 appear light (white or bright yellow-green). Therefore, in images captured under white light illumination, the pattern of the visible code 3 appears clearly with high contrast on the two-dimensional code printing section 6. Consequently, the pattern of the visible code 3 can be easily read based on images captured under visible light illumination such as white light.

[0035] Furthermore, as shown in Figure 5(A), it is difficult to determine whether the infrared light-absorbing ink 22 is printed on the black portion of the heat-sensitive color-developing layer 20 in an image captured under visible light illumination. Therefore, it is difficult to read all patterns of the infrared code 4 based on an image captured under visible light illumination. In other words, the infrared code 4 is concealed by being superimposed on the visible code 3, making it difficult to read under visible light illumination.

[0036] On the other hand, in the two-dimensional code printing section 6, the infrared code 4 is printed so as to overlap with the visible code 3. However, as shown in Figure 5(B), in an image captured under near-infrared light illumination, regardless of whether the heat-sensitive color-developing layer 20 is color-developed or not, the printed areas of the infrared light-absorbing ink 22 (infrared absorption cells of the infrared code 4) appear dark, while the unprinted areas of the infrared light-absorbing ink 22 (infrared reflection cells and background areas of the infrared code 4) appear light. This is because the heat-sensitive color-developing layer 20 of the substrate 2 has a high reflectivity of near-infrared light in both the color-developed and uncolor-developed areas, and the filter layer 9 has a high transmittance of near-infrared light. Therefore, in an image captured under near-infrared light illumination, the pattern of the infrared code 4 appears clearly with high contrast on the two-dimensional code printing section 6. Consequently, the pattern of the infrared code 4 can be easily read based on an image captured under near-infrared light illumination.

[0037] Thus, as shown in Figure 5(A), the anti-counterfeiting ticket 1 of this embodiment displays the pattern of the visible code 3 with high contrast in an image captured under visible light illumination such as white light, allowing the recorded information of the visible code 3 to be read based on the captured image. On the other hand, as shown in Figure 5(B), the pattern of the infrared code 4 displays with high contrast in an infrared image of the anti-counterfeiting ticket 1 captured under near-infrared light illumination, allowing the recorded information of the infrared code 4 to be read based on the infrared image.

[0038] Furthermore, in this embodiment, since the visible code 3 and the infrared code 4 are printed so as to overlap on the two-dimensional code printing section 6, the area of ​​the two-dimensional code printing section 6 and the imaging range when reading the two two-dimensional codes 3 and 4 can be reduced.

[0039] Furthermore, the anti-counterfeiting ticket 1 of this embodiment is superior to tickets with only visible code 3 printed on them because the infrared code 4 is difficult to read in images taken under visible light illumination, and the pattern of infrared code 4 is difficult to reproduce with the ink of a typical printer.

[0040] The configuration of the main parts of the present invention will be described below. As shown in Figure 5(A), a filter layer 9 that attenuates visible light is formed in the two-dimensional code printing section 6 in a rectangular area that includes the area for forming the visible code 3 and the area for forming the infrared code 4. As shown in Figure 2, the filter layer 9 is formed by uniformly printing a yellow-green special ink 23 over the infrared light absorbing ink 22. The special ink 23 in this embodiment is the same yellow-green color as the infrared light absorbing ink 22, but it is an ink with low absorption rate (high transmittance) of near-infrared light, and transmits near-infrared light with almost no absorption.

[0041] Because the filter layer 9 attenuates visible light (yellow-green light), as shown in Figure 5(A), in the image of the two-dimensional code printing section 6 captured under white light illumination, the non-colored areas of the thermal coloring layer 20 appear as a brighter yellow-green, with lower brightness than white. More specifically, in the non-colored areas of the thermal coloring layer 20, the non-printed areas of the infrared light absorbing ink 22 appear as a slightly brighter color (represented as a lighter gray in the figure), while the printed areas of the infrared light absorbing ink 22 appear as a slightly darker color (represented as a darker gray in the figure). On the other hand, the special ink 23 hardly absorbs near-infrared light and transmits it, so as shown in Figure 5(B), under near-infrared light illumination, the filter layer 9 hardly appears in the captured image, and an image similar to that without the filter layer 9 is captured.

[0042] In this embodiment, forming such a filter layer 9 makes it easier to read the visible code 3. Specifically, when the two-dimensional code reader performs the process of identifying the brightness of the cells 10 of the visible code 3 based on an image captured under white light illumination, it becomes less likely for errors in identifying brightness to occur. This is thought to be because, as shown in Figure 5(A), the filter layer 9 reduces the brightness of the background of the two-dimensional code printing section 6, which reduces the contrast of the infrared code 4 captured in the image and thus reduces the noise level. Although the filter layer 9 also reduces the contrast between the visible code 3 and the background, the filter layer 9 does not make the background excessively dark, so the frequency of errors in identifying the brightness of the cells 10 of the visible code 3 is reduced.

[0043] In this way, by forming a filter layer 9 that attenuates visible light in the two-dimensional code printing section 6, the visible code 3 that overlaps with the infrared code 4 becomes easier to read compared to the conventional configuration. In particular, since the filter layer 9 according to this embodiment is uniformly formed in the region including the area where the visible code 3 is formed and the area where the infrared code 4 is formed, the brightness of the background in the captured image can be uniformly reduced. Furthermore, since the filter layer 9 is uniformly formed on the top layer of the anti-counterfeiting ticket 1 so as to cover the visible code 3 and the infrared code 4, it reduces the surface irregularities of the two-dimensional code printing area 6, thereby suppressing the appearance of brightness changes based on surface irregularities as noise in the captured image. Furthermore, since the special ink 23 that forms the filter layer 9 is the same color (yellow-green) as the infrared light absorbing ink 22, there is an advantage that the brightness is not easily reduced when the special ink 23 is applied over the printed area of ​​the infrared light absorbing ink 22.

[0044] Below, Examples 2 to 5, which are modified versions of Example 1 in which the configuration of the filter layer 9 has been changed, will be described. Note that components common to Example 1 are denoted by common reference numerals in the text and figures, and detailed explanations will be omitted. [Examples]

[0045] This embodiment is characterized by replacing the filter layer 9 of Embodiment 1, which attenuates visible light, with a filter layer 9a that attenuates near-infrared light. The filter layer 9a is formed by solid printing a colorless, transparent special ink, which has a lower absorption rate of near-infrared light than the infrared light absorbing ink 22, in the same area as the filter layer 9 of Embodiment 1.

[0046] In this embodiment, the filter layer 9a absorbs and attenuates near-infrared light, though not to the same extent as the printed area of ​​the infrared light-absorbing ink 22. As shown in Figure 6(B), the brightness (reflectance of near-infrared light) of the non-printed area of ​​the infrared light-absorbing ink 22 is reduced in the image of the two-dimensional code printing area 6 captured under near-infrared light illumination. More specifically, with the infrared light-absorbing ink 22, the non-colored area of ​​the heat-sensitive color-developing layer 20 appears as a color with a slightly higher reflectance of near-infrared light (represented as a lighter gray in the figure), while the non-colored area of ​​the heat-sensitive color-developing layer 20 appears as a color with a slightly lower reflectance of near-infrared light (represented as a darker gray in the figure). On the other hand, since the special ink is colorless and transparent, as shown in Figure 6(A), under white light illumination, the filter layer 9a is hardly visible in the captured image, and an image similar to that without the filter layer 9a is captured.

[0047] In this embodiment, forming such a filter layer 9a makes it easier to read the infrared code 4. Specifically, when the two-dimensional code reader performs the process of identifying the brightness of the cells 10 of the infrared code 4 based on an image captured under near-infrared light illumination, it becomes less likely for errors in identifying brightness to occur. This is thought to be because, as shown in Figure 6(B), the filter layer 9a reduces the brightness of the background of the two-dimensional code printing section 6, which reduces the contrast of the visible code 3 captured in the image and thus reduces the noise level. Although the filter layer 9a also reduces the contrast between the infrared code 4 and the background, as long as the background does not become excessively dark due to the filter layer 9a, the frequency of errors in identifying the brightness of the cells 10 of the infrared code 4 will be reduced.

[0048] Thus, by forming a filter layer 9a that attenuates near-infrared light in the two-dimensional code printing section 6, the visible code 3 that overlaps with the infrared code 4 becomes easier to read compared to the conventional configuration. [Examples]

[0049] This embodiment is characterized by replacing the filter layer 9 of Embodiment 1, which attenuates visible light, with a filter layer 9b that attenuates both visible light and near-infrared light. The filter layer 9b is formed by solid printing a special yellow-green ink, which has a lower absorption rate of near-infrared light than the infrared light absorbing ink 22, in the same area as the filter layer 9 of Embodiment 1.

[0050] The filter layer 9b in this embodiment, like the filter layer 9 in Embodiment 1, attenuates visible light (yellow-green light). As shown in Figure 7(A), in the image of the two-dimensional code printing section 6 captured under white light illumination, the non-colored areas of the thermal coloring layer 20 appear as a bright yellow-green, with lower brightness than white. Furthermore, the filter layer 9b in this embodiment, like the filter layer 9a in Embodiment 2, absorbs and attenuates near-infrared light. As shown in Figure 7(B), in the image of the two-dimensional code printing section 6 captured under near-infrared light illumination, the brightness (reflectance of near-infrared light) of the non-printed areas of the infrared light absorbing ink 22 is reduced.

[0051] Therefore, the filter layer 9b of this embodiment makes it easier to read both the visible code 3 and the infrared code 4. [Examples]

[0052] In the first embodiment, the filter layer 9 is formed by uniformly printing special ink 23 to cover the printed area of ​​the infrared light absorbing ink 22 (see Figure 2). In contrast, in the anti-counterfeiting ticket 1a of this embodiment, as shown in Figure 8, the filter layer 9c is formed to avoid the printed area of ​​the infrared light absorbing ink 22 by arranging the layer of infrared light absorbing ink 22 and the filter layer 9c in a knockout manner. That is, in this embodiment, the layer of infrared light absorbing ink 22 is placed in the infrared absorption cell portion of the infrared code 4 in the two-dimensional code printing section 6, and the filter layer 9c made of special ink 23 is placed in the other portion (infrared reflection cell and background portion of the infrared code 4). The filter layer 9c and the layer of infrared light absorbing ink 22 are arranged over the entire area of ​​the two-dimensional code printing section 6 with virtually no gaps and virtually no overlap. Furthermore, when arranging the filter layer 9c and the infrared light absorbing ink layer 22 in a non-slip manner, it is desirable to perform trapping (tweezing) at the boundary between the two layers to prevent gaps from forming at the boundary between the two layers.

[0053] As is clear from comparing the images of the two-dimensional code printing section 6 captured under white light illumination in Example 1 (see Figure 9(A)) and this embodiment (see Figure 9(B)), in this embodiment, the contrast between the printed and unprinted areas of the infrared light absorbing ink 22 can be reduced compared to Example 1, thereby reducing the noise level. This is because the filter layer 9c does not overlap with the printed area of ​​the infrared light absorbing ink 22, resulting in the printed area of ​​the infrared light absorbing ink 22 appearing brighter than in Example 1. [Examples]

[0054] The filter layer 9d of this embodiment is characterized in that, as shown in Figure 10(B), the filter layer 9 of Embodiment 1 (see Figure 10(A)) is printed so as to overlap with the position detection pattern 11 of the visible code 3. Specifically, while the filter layer 9 of Embodiment 1 is formed over the entire overlapping area of ​​the visible code 3 and the infrared code 4, the filter layer 9d of this embodiment is formed only in the rectangular area including the position detection pattern 11 provided at the three corners of the visible code 3.

[0055] As in this embodiment, even when the filter layer 9d is formed only in the area overlapping with the position detection pattern 11 of the visible code 3, the visible code 3 becomes easier to read compared to the conventional configuration. As mentioned above, since the cells 10 of the position detection pattern 11 of the visible code 3 are not subject to the error correction function, if an error in identifying the brightness of the cells 10 occurs in the area of ​​the position detection pattern 11, it is more likely to cause problems in reading the visible code 3 than if the error occurred in other areas.

[0056] Although embodiments of the present invention have been described above, the embodiments of the present invention are not limited to the configurations of the embodiments described above, and can be modified as appropriate without departing from the spirit of the present invention.

[0057] For example, the printed materials of the present invention can be applied not only to train tickets, but also to various other types of identification documents that require protection against counterfeiting, such as admission tickets to facilities, certificates, and permits.

[0058] Furthermore, the manner in which the visible code 3 and the infrared code 4 are superimposed can also be modified without departing from the spirit of the present invention. For example, in the above embodiment, the visible code 3 and the infrared code 4 are superimposed almost completely, but they may be superimposed only partially. Also, in the above embodiment, the visible code 3 and the infrared code 4 are approximately the same size, but one of the two-dimensional codes 3 and 4 may be made larger than the other.

[0059] Furthermore, in the above embodiment, the filter layer 9 is formed on the uppermost layer of the anti-counterfeiting ticket 1, but the filter layer 9 may also be printed on the layer below the infrared light absorbing ink 22.

[0060] Furthermore, although the dark portion of the visible code 3 in the above embodiment is formed in black, it is not limited to black; it may be formed in a color similar to black. Also, although the infrared light absorbing ink 22 in the above embodiment is yellowish-green under white light illumination, inks of colors other than yellowish-green can be used as long as they are high brightness.

[0061] Furthermore, although the visible code 3 in the above embodiment is thermally printed on the heat-sensitive color-developing layer 20, the substrate 2 may be made of non-thermal paper, and the visible code 3 may be printed with ink or toner that has high transmittance of near-infrared light.

[0062] Alternatively, the two-dimensional code printing section 6 may be covered with a coating layer that does not interfere with the reading of the infrared code 4 or the visible code 3.

[0063] Furthermore, one or both of the visible code 3 and the infrared code 4 may be formed using a two-dimensional code other than a QR code.

[0064] To evaluate the present invention, the following test samples and comparative samples were prepared. The reflectance density (OD value) of each part was measured using a spectrophotometer (x-rite eXact). <Comparison product> A printed material was prepared by forming a visible code and an infrared code on the surface of a substrate under the following conditions, and this printed material was used as a comparison sample. 1. Base material Material: Plain white thermal paper Reflectance density (OD value measured with white light) Uncolored areas (white): 0.02~0.11 Colored area (black): Approximately 1.3 2. Visible Code Format: QR code (version 6) Size: 2cm (height) x 2cm (width) Error correction level: H Printing method: Thermal printing in black onto the heat-sensitive color-developing layer. 3. Infrared Code Format: QR code (version 1) Size: 1.8cm (height) x 1.8cm (width) Error correction level: H Printing method: Solid printing with yellow-green infrared light absorbing ink. Reflectance density (OD value measured with white light) Printing area on uncolored (white) areas: approximately 0.3 Printing area on the color-developing part (black): Approximately 1.3 4. Placement of the QR code Visible code 3 and infrared code 4 were printed in the same orientation, with their respective centers overlapping. 5. Filter layer none

[0065] Test sample 1 was created by producing a printed material identical to the comparison product, except that a filter layer was formed using a special ink as described below. <Test sample 1> 1. Filter layer Size: A uniform rectangle measuring 3cm x 3cm Special ink: Yellow-green near-infrared light transmitting ink Printing method: Solid print on the top layer Reflectance density (OD value of the printed area on the uncolored part of the substrate) Measured with white light: approximately 0.1 Measured with near-infrared light: Less than 0.05

[0066] Except for changing the filter layer configuration from that of Test Sample 1 as follows, printed materials similar to those of Test Sample 1 were produced and designated as Test Samples 2 to 10. <Test sample 2> The filter layer was formed by printing in a way that avoided the areas where the infrared light absorbing ink was printed (see Figure 8). <Test sample 3> The filter layer was formed by solid printing to a greater thickness than that of test sample 1. The reflectance density (OD value of the printed area on the uncolored part of the substrate) was as follows: Measured under white light: approximately 0.3 Measured with near-infrared light: Less than 0.05 <Test sample 4> The filter layer was printed with the same thickness as test sample 3, but only in the areas that overlapped with the position detection pattern 11 of the visible code 3 (see Figure 10(B)). <Test sample 5> The filter layer was formed by printing with the same thickness as test sample 3, using a die-cutting method to avoid the printed areas of the infrared light absorbing ink. <Test sample 6> The filter layer was solid-printed with a special colorless, transparent ink that has a lower absorption rate of near-infrared light than infrared light absorbing ink 22. The reflectance density of the filter layer (OD value of the printed area on the uncolored part of the substrate) was as follows: Measured under white light: Less than 0.05 Measured with near-infrared light: approximately 0.1 <Test sample 7> The same special ink as in test sample 6 was used for solid printing, but thicker than in test sample 6, to form a filter layer. The reflectance density (OD value of the printed area on the uncolored part of the substrate) was as follows: Measured under white light: Less than 0.05 Measured with near-infrared light: approximately 0.3 <Test sample 8> The filter layer was solid-printed with a special yellow-green ink that has a lower absorption rate of near-infrared light than infrared light-absorbing ink. The reflectance density of the filter layer (OD value of the printed area on the uncolored part of the substrate) was as follows: Measured with white light: approximately 0.1 Measured with near-infrared light: approximately 0.1 <Test sample 9> The same special ink as in test sample 8 was used for solid printing, but thicker than in test sample 8, to form a filter layer. The reflectance density of the filter layer (OD value of the printed area on the uncolored part of the substrate) was as follows: Measured under white light: approximately 0.3 Measured with near-infrared light: approximately 0.3 <Test sample 10> The same special ink used in test samples 8 and 9 was used for solid printing, but thicker than in test samples 8 and 9, to form a filter layer. The reflectance density of the filter layer (OD value of the printed area on the uncolored part of the substrate) was as follows: Measured under white light: approximately 0.4 Measured with near-infrared light: approximately 0.4

[0067] <Evaluation Test> For comparative samples and test samples 1-10, the two-dimensional code printing section 6 was imaged under white light illumination and near-infrared light illumination, respectively. The readability of the visible code 3 was evaluated based on the image captured under white light illumination, and the readability of the infrared code 4 was evaluated based on the image captured under near-infrared light illumination. Specifically, a two-dimensional code verification machine (LVS manufactured by Omron Corporation) was used to evaluate the cell contrast and error correction usage rate. The cell contrast was calculated by determining the difference in reflectance between the uncolored and colored areas, and evaluated in the following four stages according to the calculated value. The results are shown in Figure 11. ◎: 75% or more ○: 55-75% △: 40-55% ×: 40% or less The error correction usage rate was calculated by averaging multiple trials, and evaluated on a four-point scale based on the calculated value. The results are shown in Figure 11. ◎: 38% or less ○: 38-50% △: 50-63% ×: 63% or more

[0068] As shown in Figure 11, the comparative product showed a high error correction usage rate when reading both visible code 3 and infrared code 4 with the 2D code verification machine. This result indicates that, depending on the reading conditions, the comparative product may fail to read infrared code 4 or visible code 3, or it may take a long time to read them.

[0069] In contrast, test samples 1-5 and 8-10 showed improved error correction usage when reading visible code 3 compared to the comparison product. This result is thought to be due to the reduction in contrast of infrared code 4, which is captured in the image under white light illumination, caused by the filter layer that attenuates visible light.

[0070] Furthermore, test samples 6-10 showed improved error correction usage when reading infrared code 4 compared to the comparison sample. This result is thought to be due to the filter layer that attenuates near-infrared light, which reduced the contrast of visible code 3 captured in images under near-infrared illumination.

[0071] Furthermore, while the contrast evaluations for test samples 1-10 were lower than those for the comparison samples, the evaluations for all samples except test sample 10 were within acceptable limits. This result suggests that, if the filter layer does not excessively attenuate visible light or near-infrared light, the readability of visible code 3 and infrared code 4 can be improved by the filter layer. [Explanation of Symbols]

[0072] 1,1a Anti-counterfeiting train tickets (printed material) 2 Base material 3. Visible code (first two-dimensional code) 4. Infrared code (second two-dimensional code) 5-character information 6. Two-dimensional code printing section 7 Functional Patterns 8 Coding area 9,9a,9b,9c,9d filter layers 10 cells 11 Position detection patterns 12 Separation Patterns 13 Timing Patterns 14 Alignment Patterns 15. Data Code Area 16. Format information code area 20. Heat-sensitive color-developing layer 21 Base material body 22 Infrared light absorbing ink 23 Special Inks 30 Ticket machine paper

Claims

1. A first two-dimensional code that is easily readable under visible light illumination and difficult to read under infrared light illumination in a predetermined band, A second two-dimensional code that is difficult to read under visible light illumination and easy to read under infrared light illumination in the predetermined band, A printed material formed in such a way that overlaps, The substrate is a light-colored material with high reflectivity of infrared light in the predetermined band, The first two-dimensional code is printed in a dark color on the surface of the substrate. The second two-dimensional code is printed on the surface of the substrate using an infrared light absorbing ink with a high absorption rate of infrared light in the predetermined band. Furthermore, the printed material is characterized in that a light-colored filter layer that attenuates visible light is formed on the surface of the substrate in the area where the first two-dimensional code and the second two-dimensional code overlap.

2. A first two-dimensional code that is easily readable under visible light illumination and difficult to read under infrared light illumination in a predetermined band, A second two-dimensional code that is difficult to read under visible light illumination and easy to read under infrared light illumination in the predetermined band, A printed material formed in such a way that overlaps, The substrate is a light-colored material with high reflectivity of infrared light in the predetermined band, The first two-dimensional code is printed in a dark color on the surface of the substrate. The second two-dimensional code is printed on the surface of the substrate using an infrared light absorbing ink with a high absorption rate of infrared light in the predetermined band. Furthermore, the printed material is characterized in that a filter layer is formed on the surface of the substrate in the area where the first two-dimensional code and the second two-dimensional code overlap, which attenuates infrared light in the predetermined band.

3. A first two-dimensional code that is easily readable under visible light illumination and difficult to read under infrared light illumination in a predetermined band, A second two-dimensional code that is difficult to read under visible light illumination and easy to read under infrared light illumination in the predetermined band, A printed material formed in such a way that overlaps, The substrate is a light-colored material with high reflectivity of infrared light in the predetermined band, The first two-dimensional code is printed in a dark color on the surface of the substrate. The second two-dimensional code is printed on the surface of the substrate using an infrared light absorbing ink with a high absorption rate of infrared light in the predetermined band. Furthermore, the printed material is characterized in that a light-colored filter layer that attenuates visible light and infrared light in the predetermined band is formed on the surface of the substrate in the overlapping area of ​​the first two-dimensional code and the second two-dimensional code.

4. The printed material according to any one of claims 1 to 3, characterized in that the filter layer is uniformly formed in a region including the region where the first two-dimensional code is formed and the region where the second two-dimensional code is formed.

5. The printed material according to claim 4, characterized in that the filter layer is formed to cover the first two-dimensional code and the second two-dimensional code.

6. The filter layer is formed of a special ink with low absorption rate of infrared light in the predetermined band. The printed material according to claim 1, characterized in that the filter layer and the infrared light absorbing ink layer are arranged alternately over the entire area of ​​the first two-dimensional code formation area and the second two-dimensional code formation area.

7. The first two-dimensional code and the second two-dimensional code are, It is equipped with a position detection pattern for optically detecting the position of each two-dimensional code, The printed material according to any one of claims 1 to 3, characterized in that the filter layer is formed to overlap at least the position detection pattern in the portion where the first two-dimensional code and the second two-dimensional code overlap.

8. Printing paper for producing the printed material described in claim 1 or claim 3, The substrate is thermal paper having a substantially white heat-sensitive color-developing layer formed on its surface, On the surface of the substrate, The second two-dimensional code is pre-printed with the infrared light absorbing ink, The filter layer is pre-formed in the area where the second two-dimensional code is formed. Printing paper characterized in that the first two-dimensional code is configured to be thermally printable at a position overlapping with the second two-dimensional code.

Images