Printed materials

Abstract

In printed materials that include both black and white visible two-dimensional codes and concealed two-dimensional codes that are difficult to identify under visible light illumination, this invention provides a configuration that makes it easy to read the concealed two-dimensional codes even in environments with ambient light. [Solution] A visible two-dimensional code 3 and a concealed two-dimensional code are placed side by side with a gap between them, and an infrared absorbing solid printing layer 10a made of ink that absorbs near-infrared light and an infrared transmitting solid printing layer 10b made of ink that transmits near-infrared light and is substantially the same color as the infrared absorbing solid printing layer 10a are placed alternately in the background area around the concealed two-dimensional code. The infrared absorbing cell portion is formed with the infrared absorbing solid printing layer 10a, the infrared reflecting cell portion is formed with the infrared transmitting solid printing layer 10b, and the background portion is formed with either the infrared absorbing solid printing layer 10a or the infrared transmitting solid printing layer 10b.

Description

Technical Field

[0001] The present invention relates to a printed matter on which a two-dimensional code that is difficult to identify under visible light illumination is printed.

Background Art

[0002] General two-dimensional codes such as QR Codes (registered trademark) are configured to be able to easily read recorded information with a smartphone or the like, and have poor information confidentiality. Therefore, in addition to ordinary black-and-white two-dimensional codes (visible two-dimensional codes), a two-dimensional code that is difficult to read under visible light illumination (hidden two-dimensional code) is provided, and a printed matter in which information to be concealed is recorded in the hidden two-dimensional code has been proposed (for example, Patent Document 1).

[0003] In the printed matter of Patent Document 1, a hidden two-dimensional code is arranged overlapping the visible two-dimensional code. The hidden two-dimensional code is printed with a light-colored toner that absorbs near-infrared light, and the visible two-dimensional code is printed black with a toner that transmits near-infrared light. In such a configuration, the pattern of the hidden two-dimensional code does not become completely transparent, but since it overlaps with the black-and-white visible two-dimensional code, the pattern of the hidden two-dimensional code is difficult to identify under visible light illumination. However, in the captured image under near-infrared light illumination, the pattern of the visible two-dimensional code disappears, and only the pattern of the hidden two-dimensional code appears clearly, so the hidden two-dimensional code can be read. Since a general image sensor such as a CMOS has sensitivity in the near-infrared light band, the printed matter of Patent Document 1 can capture the patterns of both the visible two-dimensional code and the hidden two-dimensional code with the same imaging device by switching between visible light illumination and near-infrared light illumination.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The concealed two-dimensional code described in Patent Document 1 above is not suitable for reading concealed two-dimensional codes in environments where ambient light is likely to be present, such as outdoors. This is because when imaging under near-infrared illumination, if visible light is mixed in as ambient light, the pattern of the visible two-dimensional code may be captured in the image, making it impossible to identify the pattern of the concealed two-dimensional code.

[0006] When imaging near-infrared light, attaching a visible light cut filter to the imaging device can prevent visible two-dimensional codes from being captured. However, when imaging visible light, the visible light cut filter must be removed, making it unsuitable for imaging both visible and hidden two-dimensional codes with the same imaging device.

[0007] This invention has been made in view of the current situation, and aims to provide a configuration that makes it easier to read concealed two-dimensional codes even in environments with ambient light compared to the conventional configuration described above. [Means for solving the problem]

[0008] The present invention relates to a printed material having a first two-dimensional code that records information by a pattern of light-colored cells and dark-colored cells, and a second two-dimensional code that records information by a pattern of first and second cells having different reflectances of infrared light in a predetermined band, arranged on one side, wherein the second two-dimensional code and the background portion surrounding the second two-dimensional code are arranged alternately with a first solid printing layer formed of an ink or toner having infrared light absorption characteristics in the predetermined band and a second solid printing layer of substantially the same color as the first solid printing layer, formed of an ink or toner that does not have infrared light absorption characteristics in the predetermined band, the first solid printing layer is arranged in the first cell portion, the second solid printing layer is arranged in the second cell portion, and either the first solid printing layer or the second solid printing layer is arranged in the background portion. Here, the background area surrounding the QR code refers not to the background of the entire printed material, but to the margin (whitespace) necessary for reading the QR code in question.

[0009] In this configuration, the second two-dimensional code appears almost patternless under visible light illumination, so the pattern of the second two-dimensional code is concealed to the point of being difficult to identify. On the other hand, if the area where the second two-dimensional code is located is imaged under illumination of infrared light of a predetermined wavelength (hereinafter also simply referred to as "infrared light"), the pattern of the second two-dimensional code appears clearly in the captured image, making it easy to read the second two-dimensional code under infrared light illumination. Here, in the present invention, the second two-dimensional code is almost the same color as the surrounding background, and the reflectivity of visible light is almost uniform, so even if visible light is mixed in as ambient light when capturing an image under infrared light illumination, there is no impediment to identifying the pattern of the second two-dimensional code. In other words, the printed material of the present invention allows for easy reading of the concealed second two-dimensional code even in environments where ambient light is likely to be present, such as outdoors. Furthermore, since the area where the second two-dimensional code is placed in the printed material of the present invention is virtually patternless, it can also improve the design compared to cases where the two-dimensional code is concealed with a camouflage pattern such as a background pattern.

[0010] In the present invention, it is proposed that the color of the first cell portion, the color of the second cell portion, and the color of the background portion surrounding the second two-dimensional code have a color difference (ΔE*ab) of 5.0 or less as defined in JIS Z8781.

[0011] Even if the first solid printing layer and the second solid printing layer according to the present invention are not exactly the same color, as long as they are similar enough to be difficult to distinguish, the pattern of the second two-dimensional code can be suitably concealed. According to the inventor's research, it has been confirmed that when the color difference (ΔE*ab as defined in JIS Z8781) between the first cell portion, the second cell portion, and the background portion surrounding the second two-dimensional code is at least 5.0 or less, the pattern of the second two-dimensional code can be concealed to the point of being difficult to distinguish under visible light illumination.

[0012] In the present invention, it is proposed that the first solid printing layer and the second solid printing layer are arranged in a punch-out manner such that their overlap is 0.2 mm or less in width and the gap between them is 0.2 mm or less in width, with respect to the second two-dimensional code and the background portion surrounding the second two-dimensional code.

[0013] When arranging the first solid print layer and the second solid print layer according to the present invention using a knockout method, it is desirable to minimize gaps and overlaps in the solid print layers at the boundary between them as much as possible. According to the inventor's research, even if there are some gaps or overlaps at the boundary between the two solid print layers due to misregistration or the like, it has been confirmed that the second two-dimensional code can be concealed without being noticeable under visible light illumination if the width of the overlap or gap is at least 0.2 mm or less. Generally, gaps between solid print layers are more noticeable than overlaps between solid print layers, so it is suggested to perform trapping (knockout alignment) at the boundary between the two solid print layers.

[0014] Furthermore, it is desirable that the two solid printing layers according to the present invention be light in color. This is because when the solid printing layers are also placed on the first two-dimensional code and its background, the contrast between light and dark in the first two-dimensional code can be improved, thereby improving readability. In addition, when the solid printing layers are placed over the entire surface of one side of the printed material, it becomes possible to clearly print text information and the like on the portion where the solid printing layers are formed.

[0015] In the present invention, the first two-dimensional code and the second two-dimensional code are arranged side by side with a gap between them, the first solid printing layer and the second solid printing layer are substantially the same light color, the background portion around the first two-dimensional code and the background portion around the second two-dimensional code are continuous, and it is proposed that the first solid printing layer or the second solid printing layer is also formed on the first two-dimensional code and the background portion around the first two-dimensional code.

[0016] In such a configuration, since the second two-dimensional code can be concealed around the first two-dimensional code without a sense of incongruity, the design property of the printed matter can be improved.

[0017] Also, in the present invention, it is proposed that a plurality of the second two-dimensional codes for recording the same information are arranged around the first two-dimensional code.

[0018] The second two-dimensional code according to the present invention is concealed so as to be difficult to visually recognize, and there is a possibility that it may take time to fit it within the imaging range when reading the second two-dimensional code. However, with such a configuration, it is sufficient to fit at least one of the second two-dimensional codes arranged in a plurality around the first two-dimensional code within the imaging range, so that the recorded information of the second two-dimensional code becomes easier to read.

[0019] Also, in the present invention, it is proposed that the first solid printing layer and the second solid printing layer are arranged in a non-overlapping manner over the entire one surface side.

[0020] With such a configuration, since the second two-dimensional code can be concealed in the background of the printed matter without a sense of incongruity, the design property of the printed matter can be further improved.

Effect of the Invention

[0021] As described above, according to the printed matter of the present invention, a two-dimensional code that records information with a pattern of cells having different reflectance of infrared light is concealed so as to be difficult to identify under visible light illumination, and can be easily read under infrared light illumination even in an environment where external light is likely to be mixed.

Brief Description of the Drawings

[0022] [Figure 1] (A) is a surface view of the printed matter 1 of the embodiment. (B) is a surface view when the printed matter 1 is imaged with near-infrared light. [Figure 2] It is a perspective view of the printed matter 1 showing the solid printing layers 10a and 10b separated. [Figure 3] It is an enlarged perspective view of the printed matter 1 showing the infrared absorption solid printing layer 10a separated. [Figure 4] (A) Visible code printing section 6a and (B) are explanatory diagrams showing the layer structure of the hidden code printing section 6b. [Figure 5] It is an explanatory diagram showing the boundary portion between the infrared absorption solid printing layer 10a and the infrared transmission solid printing layer 10b. [Figure 6] It is a surface view of the printed matter 1a of the modified example.

Embodiments for Carrying Out the Invention

[0023] Embodiments of the present invention will be described based on the following examples. In the following examples, the first two-dimensional code according to the present invention corresponds to the visible two-dimensional code 3, and the second two-dimensional code according to the present invention corresponds to the hidden two-dimensional code 4. Also, the first solid printing layer and the second solid printing layer according to the present invention respectively correspond to the infrared absorption solid printing layer 10a and the infrared transmission solid printing layer 10b. Further, the first cell according to the present invention corresponds to the infrared absorption cell, and the second cell corresponds to the infrared reflection cell. Also, the infrared light in the predetermined band according to the present invention corresponds to near-infrared light (particularly light with a wavelength of 750 nm to 900 nm).

[0024] The printed matter 1 of this example is a one-day use ticket for facilities such as amusement parks. As shown in Fig. 1(A), the background on the front side of the printed matter 1 is entirely plain with a light yellow-green color (represented by light gray in the figure), and character information 5a to 5c is printed in black at the upper and lower parts. And in the central part on the front side of the printed matter 1, two two-dimensional code printing sections 6a and 6b where the two-dimensional codes 3 and 4 are printed are arranged side by side with a gap therebetween vertically. Among the two two-dimensional code printing sections 6a and 6b, the visible code printing section 6a above has the visible two-dimensional code 3 printed in a manner that is easy to visually recognize, and the hidden code printing section 6b below has the hidden two-dimensional code 4 printed in a manner that is difficult to visually recognize. Information for confirming, for example, the validity of the ticket is recorded in the visible two-dimensional code 3 and the hidden two-dimensional code 4. Although not shown in the figure, the back side of the printed matter 1 is plain white.

[0025] Visible two-dimensional code 3 is a common QR code that records information using a pattern of light-colored (pale yellowish-green) and dark-colored (black) cells. As shown in Figure 1(A), the visible two-dimensional code 3 is printed in black on the pale yellowish-green background of printed material 1, with the dark-colored cells printed in black. There is almost no difference in near-infrared light reflectivity between the light-colored and dark-colored cell portions of the visible two-dimensional code 3, and as shown in Figure 1(B), the pattern of visible two-dimensional code 3 is difficult to distinguish in an image of printed material 1 taken under near-infrared light illumination.

[0026] The concealed two-dimensional code 4 is basically a two-dimensional code that conforms to the QR code standard (JIS X 0510). However, the concealed two-dimensional code 4 does not record information using a pattern of light-colored and dark-colored cells, but rather using a pattern of infrared-absorbing cells with low near-infrared reflectivity and infrared-reflecting cells with high near-infrared reflectivity. Both the infrared-absorbing and infrared-reflecting cells are light yellowish-green, which is approximately the same as the background color of the printed material 1. Therefore, as shown in Figure 1(A), under general visible light illumination, the concealed code printing area 6b appears almost patternless, making it difficult to identify the pattern of the concealed two-dimensional code 4. On the other hand, as shown in Figure 1(B), in an image of the printed material 1 taken under near-infrared light illumination, the infrared-absorbing cell portion appears darker than the infrared-reflecting cell portion and the background portion, making the pattern of the concealed two-dimensional code 4 easily identifiable on the concealed code printing area 6b.

[0027] The layer structure of printed material 1 is described below. As shown in Figures 2 and 3, the printed material 1 comprises a substrate 2 and solid printing layers 10a and 10b coated on the front surface of the substrate 2. The substrate 2 is plain white thermal paper, and the text information 5a to 5c and the pattern of the visible two-dimensional code 3 of the printed material 1 are formed by thermal printing, which causes the heat-sensitive color-developing layer on the surface of the substrate 2 to turn black.

[0028] The solid printing layers 10a and 10b are composed of an infrared absorbing solid printing layer 10a made of an infrared light absorbing ink that has the property of absorbing near-infrared light, and an infrared transmitting solid printing layer 10b made of an infrared light transmitting ink that does not have the property of absorbing near-infrared light. Although the infrared light absorbing ink and the infrared light transmitting ink have significantly different absorption rates of near-infrared light, both are light yellowish-green inks that transmit the base color, and the infrared absorbing solid printing layer 10a and the infrared transmitting solid printing layer 10b are approximately the same light yellowish-green color. The infrared absorbing solid printing layer 10a and the infrared transmitting solid printing layer 10b are formed by solid printing of the infrared light absorbing ink and the infrared light transmitting ink, respectively, with the same film thickness. Then, by arranging the infrared-absorbing solid printing layer 10a and the infrared-transmitting solid printing layer 10b across the entire front surface of the white substrate 2 with virtually no gaps and virtually no overlap, a nearly patternless light yellowish-green background is formed on the front surface of the printed material 1. In addition, the black color of the colored portion of the heat-sensitive color-developing layer is displayed.

[0029] Figures 4(A) and 4(B) are explanatory diagrams showing the layer structure of the visible code printing section 6a and the concealed code printing section 6b. As described above, the substrate 2 is plain white thermal paper and consists of a paper substrate body 2a and a thermal color-developing layer 2b coated on the front side of the substrate body 2a. As shown in Figure 4(A), in the visible code printing section 6a, the thermal color-developing layer 2b develops into a color-developed area 2bb that turns black in the dark cell portions 13 of the visible two-dimensional code 3, and into an uncolored white area 2ba in the other parts. In addition, a light yellow-green infrared transparent solid printing layer 10b is uniformly arranged on top of the thermal color-developing layer 2b throughout the entire visible code printing section 6a. Due to this layer structure, as shown in Figure 1(A), the dark cell portions 13 appear black in the visible code printing section 6a, and the other parts, namely the light cell portions 12 and the background portion 14, appear light yellow-green. Furthermore, since the heat-sensitive color-developing layer 2b transmits near-infrared light without absorbing it in either the white uncolored area 2ba or the black colored area 2bb, as shown in Figure 1(B), the pattern of the visible two-dimensional code 3 becomes difficult to distinguish in an image captured using only near-infrared light.

[0030] As shown in Figure 4(B), in the concealed code printing section 6b, the thermal coloring layer 2b is uncolored 2ba (white) throughout. Then, solid printing layers 10a and 10b are placed on top of the uncolored thermal coloring layer 2b. Here, as shown in Figures 2 to 4, the infrared absorbing solid printing layer 10a is placed only in the infrared absorbing cell portion 15 of the concealed two-dimensional code 4, and the infrared transmitting solid printing layer 10b is placed in all other areas on the front side of the printed material 1. With this layer structure, the surface of the substrate 2 reflects near-infrared light, but in the area where the infrared absorbing solid printing layer 10a is placed, the reflectivity of near-infrared light is low because the infrared absorbing solid printing layer 10a absorbs most of the near-infrared light. On the other hand, in the area where the infrared transmitting solid printing layer 10b is placed, the reflectivity of near-infrared light is high because most of the near-infrared light passes through the infrared transmitting solid printing layer 10b and is reflected at the surface of the substrate 2. Therefore, as shown in Figure 1(B), in an image captured using only near-infrared light, the infrared absorption cell portion 15 of the concealed code printing section 6b appears dark, while the other portions, namely the infrared reflection cell portion 16 and the background portion 17, appear light, making it easy to identify the pattern of the concealed two-dimensional code 4.

[0031] Ideally, the infrared-absorbing solid printing layer 10a of the infrared-absorbing ink and the infrared-transmitting solid printing layer 10b of the infrared-transmitting ink should be arranged without gaps or overlaps by knockout. However, in reality, as shown in Figure 5(A), slight gaps 18 and overlaps 19 occur at the boundary due to misregistration. Nevertheless, if the gaps 18 and overlaps 19 at the boundary between the infrared-absorbing solid printing layer 10a and the infrared-transmitting solid printing layer 10b are small enough to be difficult to distinguish, the concealed code printing area 6b will appear almost patternless, and the concealed two-dimensional code 4 can be sufficiently concealed. Specifically, if the gap between the infrared absorbing solid printing layer 10a and the infrared transmitting solid printing layer 10b is at least 0.2 mm in width, and the overlap between the infrared absorbing solid printing layer 10a and the infrared transmitting solid printing layer 10b is at least 0.2 mm in width, then there will be no problem in concealing the concealed two-dimensional code 4. Furthermore, since the areas where the surface color (white) of the substrate 2 is exposed due to the gap 18 between the infrared-absorbing solid printing layer 10a and the infrared-transmitting solid printing layer 10b are more noticeable than the areas where the light yellowish-green color becomes darker due to the overlap 19 between the infrared-absorbing solid printing layer 10a and the infrared-transmitting solid printing layer 10b, it is proposed to perform a trapping process (tweezers) at the boundary between the infrared-absorbing solid printing layer 10a and the infrared-transmitting solid printing layer 10b, as shown in Figure 5(B), to prevent gaps 18 from forming between the infrared-absorbing solid printing layer 10a and the infrared-transmitting solid printing layer 10b. The trapping width is preferably 0.05 to 0.10 mm. In the trapping process, either the infrared-absorbing solid printing layer 10a or the infrared-transmitting solid printing layer 10b may be thickened, or both may be thickened.

[0032] In this embodiment, printed material 1 (amusement park ticket) is proposed to record information for verifying the validity of the ticket in a visible two-dimensional code 3 and a concealed two-dimensional code 4. When using an attraction, the recorded information in the visible two-dimensional code 3 and the concealed two-dimensional code 4 is read respectively to verify the validity of the ticket. The recorded information in the visible two-dimensional code 3 and the concealed two-dimensional code 4 can be read by successively taking images with visible light illumination and infrared light illumination, and then decoding the recorded information in the visible two-dimensional code 3 and the concealed two-dimensional code 4 based on the respective captured images.

[0033] In this embodiment, printed material 1 (amusement park ticket) is proposed to record common information (such as authenticity verification information) common to each ticket in the concealed two-dimensional code 4, and variable information (such as ticket ID and expiration date) that differs for each ticket in the visible two-dimensional code 3. This is because the visible two-dimensional code 3, formed by thermal printing, is more suitable for variable printing than the concealed two-dimensional code 4, which is formed by combining an infrared absorbing solid printing layer 10a and an infrared transparent solid printing layer 10b. For example, one proposed method for manufacturing such printed material 1 is to produce a large quantity of ticket paper coated with an infrared absorbing solid printing layer 10a and an infrared transmitting solid printing layer 10b at a printing factory or the like, and then issue the tickets at the amusement park's ticket office by thermal printing text information 5a to 5c and a visible two-dimensional code 3 onto the heat-sensitive color-developing layer 2b of the ticket paper.

[0034] As described above, in this embodiment, the printed material 1 has a nearly patternless hidden code printing area 6b on which the hidden two-dimensional code 4 is printed, and the hidden two-dimensional code 4 is properly concealed under visible light illumination. On the other hand, if the hidden code printing area 6b is imaged under near-infrared light illumination, the pattern of the hidden two-dimensional code 4 becomes clearly visible as shown in Figure 1(B), so the hidden two-dimensional code 4 can be easily read under near-infrared light illumination. In particular, since the hidden code printing area 6b is nearly patternless, even if visible light is mixed in as ambient light when imaging under near-infrared light illumination, there is no impediment to the identification of the hidden two-dimensional code 4. In other words, the printed material 1 (amusement park ticket) of this embodiment is expected to be read in environments where ambient light is likely to be present, such as outdoors, but even in such environments, the hidden two-dimensional code 4 can be easily read. Furthermore, since the concealed code printing section 6b is virtually patternless, it has the advantage of improving the aesthetic appeal of the printed material 1 compared to concealing it with a camouflage pattern.

[0035] Furthermore, in this embodiment, the background portion 14 of the visible two-dimensional code 3 and the background portion 17 of the concealed two-dimensional code 4 are continuous with the same light yellow-green background, which has the advantage of concealing the concealed two-dimensional code 4 around the visible two-dimensional code 3 without any sense of incongruity. In particular, in this embodiment, the infrared absorbing solid printing layer 10a and the infrared transmitting solid printing layer 10b are formed on the entire front surface of the printed material 1, making the entire background of the printed material 1 a nearly patternless light yellow-green, so the concealed two-dimensional code 4 can be concealed without any sense of incongruity, without the presence of the concealed two-dimensional code 4 being noticeable.

[0036] 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.

[0037] For example, the printed materials of the present invention can be applied to various types of documents, such as railway tickets, event tickets, certificates, and permits, in addition to the amusement park admission tickets mentioned in the examples.

[0038] Furthermore, in the above embodiment, the concealed two-dimensional code 4 is positioned below the visible two-dimensional code 3, but the arrangement of the visible two-dimensional code 3 and the concealed two-dimensional code 4 can be changed as appropriate. It is desirable that the visible two-dimensional code 3 and the concealed two-dimensional code 4 be placed close together, within a range that does not hinder the reading of each, so that the visible code printing area 6a and the concealed code printing area 6b can be easily captured in the imaging range at the same time.

[0039] Furthermore, as shown in Figure 6, multiple concealed code printing units 6b may be arranged above, below, to the left and right of the visible code printing unit 6a, so that multiple concealed two-dimensional codes 4 recording the same information can be arranged around the visible two-dimensional code 3. In the above embodiment, the concealed two-dimensional code 4 is difficult to see, and it is difficult to capture the entire concealed two-dimensional code 4 within the imaging range without knowing the position of the concealed code printing unit 6b. However, as shown in Figure 6, if multiple concealed two-dimensional codes 4 are arranged around the visible two-dimensional code 3, it is sufficient if at least one concealed two-dimensional code 4 is within the imaging range, making it easier to read the recorded information of the concealed two-dimensional code 4.

[0040] Furthermore, in the above embodiment, the visible two-dimensional code 3 is larger than the concealed two-dimensional code 4, but the concealed two-dimensional code 4 may be made larger than the visible two-dimensional code 3, or the two two-dimensional codes 3 and 4 may be made the same size.

[0041] Furthermore, the visible two-dimensional code 3 and the hidden two-dimensional code 4 may be two-dimensional codes other than QR codes, either one or both.

[0042] Furthermore, an overcoat layer that does not hinder the reading of the visible two-dimensional code 3 or the concealed two-dimensional code 4 may be provided on the two-dimensional code printing sections 6a and 6b.

[0043] Furthermore, in the above embodiment, the base material 2 is plain white, but the surface of the base material 2 may have a colored tint, or a background pattern may be formed on parts other than the two-dimensional code printing areas 6a and 6b.

[0044] Furthermore, while the visible two-dimensional code 3 and character information 5a to 5c in the above embodiment are thermally printed on the heat-sensitive color-developing layer 2b, the substrate 2 may be made of non-thermal paper, and the visible two-dimensional code 3 and character information 5a to 5c may be printed with black ink or toner. Also, the visible two-dimensional code 3 may be printed in a color other than black.

[0045] Furthermore, in the above embodiment, an infrared-transmitting solid printing layer 10b is formed on the visible code printing section 6a, and the light-colored cell portion 12 and background portion 14 of the visible two-dimensional code 3 are light yellowish-green. However, an infrared-absorbing solid printing layer 10a or an infrared-transmitting solid printing layer 10b may not be formed on the visible code printing section 6a, and the light-colored cell portion 12 and background portion 14 of the visible two-dimensional code 3 may be white (the surface color of the substrate 2).

[0046] Furthermore, the arrangement of the infrared absorbing solid printing layer 10a and the infrared transmitting solid printing layer 10b may be reversed from that of the embodiment. This is because QR codes are configured to be readable even when the brightness is reversed.

[0047] Furthermore, in the above embodiment, the visible two-dimensional code 3 and character information 5a to 5c become unclear in the image captured under near-infrared illumination. However, the system may be configured so that the visible two-dimensional code 3 and character information 5a to 5c appear clearly in the image captured under near-infrared illumination.

[0048] To evaluate the present invention, the following test samples and comparative samples were prepared. <Test sample> A printed material of the present invention was prepared by forming a visible two-dimensional code 3 and an opaque two-dimensional code 4 at intervals on the surface of a substrate 2 under the following conditions, and this printed material was used as a test sample. 1. Base material Material: Plain white thermal paper 2. Visible 2D code Format: QR code (version 6) Size: 2cm (height) x 2cm (width) Printing method: Thermal printing in black onto the heat-sensitive color-developing layer. 3. Concealed 2D Code Format: QR code (version 1) Size: 1.5cm (height) x 1.5cm (width) 4. Placement of visible and hidden 2D codes A visible 2D code and a hidden 2D code were placed in the same orientation, with approximately 0.5 cm of space between them, one above the other. 5. Solid print layer An infrared-absorbing solid print layer 10a and an infrared-transmitting solid print layer 10b were coated by offset printing using the following inks, with the same film thickness. Infrared Absorption Solid Printing Layer: A light yellowish-green UV-curable ink with near-infrared light absorption properties. Infrared-transmitting solid printing layer: A light yellowish-green UV-curing ink that does not have near-infrared light absorption properties. Test sample 1 was created by not performing trapping at the boundary between the infrared absorbing solid printing layer 10a and the infrared transmitting solid printing layer 10b, and ensuring that the infrared absorbing solid printing layer 10a and the infrared transmitting solid printing layer 10b were positioned without any misalignment. Test samples 2 through 5 were created by selecting those with misalignment of approximately 0.05 mm, 0.1 mm, 0.15 mm, and 0.2 mm, in order from smallest to largest misalignment.

[0049] <Comparison Item 1> Comparative sample 1 was created by omitting the infrared-transmitting solid printing layer 10b from the configuration of the above test sample. In other words, in comparative sample 1, the infrared-absorbing solid printing layer 10a is placed only in the infrared-absorbing cell portion of the concealed two-dimensional code 4, and the white surface of the substrate 2 is visible in the other parts.

[0050] <Comparison item 2> Based on the configuration of the above test sample, comparative sample 2 was created by not overlapping the infrared absorbing solid printing layer 10a and the infrared transmitting solid printing layer 10b, and instead placing the infrared transmitting solid printing layer 10b across the entire front surface of the printed material 1. In comparative sample 2, the infrared absorbing solid printing layer 10a and the infrared transmitting solid printing layer 10b overlap in the infrared absorbing cell portion of the concealed two-dimensional code 4, resulting in the infrared absorbing cell portion appearing in a darker color than the surrounding light yellowish-green.

[0051] <Rating 1> Under the following conditions, the following parts were color-measured according to JIS Z8722:2009, and the values ​​of L*, a*, and b* were calculated. 1. The portion on the front side of the substrate 2 where only the infrared absorption solid printing layer 10a is placed. L*87.63 a*-8.24 b*28.58 2. The portion on the front side of the substrate 2 where only the infrared transparent solid print layer 10b is placed. L*88.32 a*-6.95 b*25.10 The color difference (ΔE*ab) between parts 1 and 2, calculated based on JIS Z8781, was 3.77.

[0052] <Rating 2> For each of the test samples 1-5 and comparative samples 1 and 2, the concealed code printing area 6b was visually inspected from a distance of 30 cm under a typical daylight-white fluorescent light. As a result, the concealed code printing area 6b of test samples 1-5 all appeared as a nearly patternless faint yellowish-green, and the two-dimensional code (concealed two-dimensional code 4) was difficult to discern. In the concealed code printing area 6b of comparative sample 1, a pattern of a faint yellowish-green two-dimensional code (concealed two-dimensional code 4) was observed against a white background. In the concealed code printing area 6b of comparative sample 2, a pattern of a two-dimensional code (concealed two-dimensional code 4) consisting of varying shades of faint yellowish-green was observed. These results suggest that the concealed two-dimensional code 4 is adequately concealed in test samples 1-5, while the concealment of the concealed two-dimensional code 4 is insufficient in comparative samples 1 and 2. <Rating 3> Using the standard camera of an iPhone (iOS 11 or later), the concealed code printing area 6b of test products 1-5 and comparative products 1 and 2 was imaged under visible light illumination, and an attempt was made to read the recorded information of the concealed two-dimensional code 4. As a result, reading the recorded information of the concealed two-dimensional code 4 failed for test products 1-5. On the other hand, the recorded information of the concealed two-dimensional code 4 was successfully read for comparative products 1 and 2. This result suggests that the concealed two-dimensional code 4 is properly concealed in test products 1-5, while the concealment of the concealed two-dimensional code 4 is insufficient in comparative products 1 and 2. <Rating 4> For each of the test samples 1-5 and comparative samples 1 and 2, the visible code printing area 6a was imaged under visible light illumination, and the pattern of the visible two-dimensional code 3 in the captured image was evaluated using a "QR checker" manufactured by Denso Wave. As a result, for all of the test samples 1-5 and comparative samples 1 and 2, the pattern of the visible two-dimensional code 3 in the captured image was good in terms of both contrast and clarity. This result suggests that the readability of the visible two-dimensional code 3 is not impaired by the solid printing layers 10a and 10b.

[0053] Based on the results of the evaluation tests described above, it was confirmed that the printed material of the present invention can properly conceal the concealed two-dimensional code 4 without impairing the readability of the visible two-dimensional code 3 under visible light illumination. [Explanation of Symbols]

[0054] 1,1a Printed materials 2 Base material 2a Base material body 2b Heat-sensitive color-developing layer 2ba Uncolored area 2bb colored area 3. Visible two-dimensional code (first two-dimensional code) 4. Concealed 2D code (second 2D code) 5a~5d Character information 6a Visible code printing section (two-dimensional code printing section) 6b Concealed code printing section (two-dimensional code printing section) 10a Infrared absorption solid printing layer (first solid printing layer) 10b Infrared-transparent solid printing layer (second solid printing layer) 12 Light-colored cell area 13 Dark cell area 14 Background part 15. Infrared absorption cell portion 16 Infrared transmission cell portion 17 Background part 18 gaps 19 Overlap

Claims

1. A first two-dimensional code that records information using a pattern of light-colored and dark-colored cells, A second two-dimensional code that records information based on the patterns of a first cell and a second cell having different reflectances of infrared light in a predetermined band, and A printed material in which at least one side is arranged The aforementioned second two-dimensional code and the background area surrounding the aforementioned second two-dimensional code are: A first solid printing layer formed with an ink or toner having infrared light absorption characteristics in the predetermined band, A second solid print layer, which is substantially the same color as the first solid print layer, is formed with an ink or toner that does not have the infrared light absorption characteristics of the predetermined band. They are arranged in a random order. The first cell portion is provided with the first solid printing layer. The second cell portion is provided with the second solid printing layer. The printed material is characterized in that one of the first solid printing layer and the second solid printing layer is arranged in the background portion.

2. The printed material according to claim 1, characterized in that the color of the first cell portion, the color of the second cell portion, and the color of the background portion surrounding the second two-dimensional code have a color difference (ΔE*ab) of 5.0 or less as defined in JIS Z8781.

3. The printed material according to claim 1 or 2, characterized in that the first solid printing layer and the second solid printing layer are arranged in a die-cut manner such that their overlap is 0.2 mm or less in width and the gap between them is 0.2 mm or less in width, in the background portion surrounding the second two-dimensional code and the second two-dimensional code.

4. The first two-dimensional code and the second two-dimensional code are arranged side by side with a gap between them. The first solid printing layer and the second solid printing layer are substantially the same light color. The background area surrounding the first two-dimensional code and the background area surrounding the second two-dimensional code are continuous. The printed material according to claim 1 or 2, characterized in that the first solid printing layer or the second solid printing layer is also formed on the first two-dimensional code and on the background portion surrounding the first two-dimensional code.

5. The printed material according to claim 4, characterized in that a plurality of second two-dimensional codes for recording the same information are arranged around the first two-dimensional code.

6. The printed material according to claim 4, characterized in that the first solid printing layer and the second solid printing layer are arranged in a staggered manner across the entire area of ​​the one side.

Images