Marker, marker multi-facet

Abstract

To provide a marker which is unnoticeable, and a marker step-and-repeat imposition body.SOLUTION: A marker 1 is formed by depositing a first reflection layer 20 reflecting visible light and near infrared rays and a near infrared ray absorbing layer 30 for absorbing at least near infrared rays, on each other. The first reflection layer 20 is partially removed for the near infrared ray absorber layer 30, and has a mark 2 displayed as a dependent shape by near infrared rays reflected by layers other than the near infrared ray absorber layer 30. This makes it possible to make the mark 2 unnoticeable under visible light and to observe the mark 2 under near infrared rays.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a marker and a multi-faceted marker body. [Background technology]

[0002] Markers are attached to objects so that various automatic control devices can recognize them, thereby achieving high-precision automatic control. Such markers are used, for example, to control robots in production sites and in space missions. Conventionally, markers printed on paper have been widely used because they are easy to make, but with such simple markers, the boundaries of the marks are unclear, and the size of the marks and the spacing between multiple marks change due to the expansion and contraction of the paper, making it difficult to ensure sufficient accuracy when high-precision control is required. In view of this, as a technique for realizing a highly accurate marker, Patent Document 1 discloses a technique in which holes are made in a metal plate by cutting and resin is embedded therein to form a marker. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 5-312521 Summary of the Invention [Problem to be solved by the invention]

[0004] However, with the marker in Patent Document 1, the mark is visible to the human eye, and so there is a risk of it creating an awkward feeling when placed and used in a living space or the like.

[0005] An object of the present invention is to provide a marker and a multi-faceted marker body that are not noticeable to the human eye. [Means for solving the problem]

[0006] The present invention solves the above problems by the following solving means. Note that, for ease of understanding, the following description will be given with reference numerals corresponding to the embodiments of the present invention, but the present invention is not limited thereto.

[0007] A first invention is a marker (1, 1B, 1C, 1D, 1E, 1F) comprising a first reflective layer (20) that reflects visible light and near-infrared light, and a near-infrared light absorbing layer (30, 30E, 31, 31F) that absorbs at least near-infrared light, which are arranged in a stacked manner, one of the first reflective layer (20) and the near-infrared light absorbing layer (30, 30E, 31, 31F) having a portion missing from the other, and comprising a mark (2) that is displayed as an independent shape by near-infrared light reflected by layers other than the near-infrared light absorbing layer (30, 30E, 31, 31F).

[0008] A second invention is a marker (1, 1B, 1C, 1D, 1E, 1F) according to the first invention, in which the first reflective layer (20, 20C) partially disposed, the near-infrared light absorbing layer (30), and a second reflective layer (40) that reflects visible light and near-infrared light are directly or indirectly stacked in this order, and the near-infrared light absorbing layer (30, 30E, 31, 31F) transmits visible light.

[0009] A third invention is a marker (1C) according to the second invention, wherein the first reflective layer (20C) contains a dye or pigment that approximates the color of visible light reflected and returned by the second reflective layer (40) through the near-infrared light absorbing layer (30).

[0010] A fourth invention is a marker (1D) according to the first invention, in which the first reflective layer (20), the partially-arranged near-infrared light absorbing layer (31), and a visible light absorbing near-infrared light transmitting layer (50) that absorbs visible light and transmits near-infrared light are arranged directly or indirectly in this order and are arranged adjacent to the near-infrared light absorbing layer (30) at the same level as the layer in which the near-infrared light absorbing layer (30) is arranged in a portion in which the near-infrared light absorbing layer (30) is not arranged, and that absorbs visible light and transmits near-infrared light, and the near-infrared light absorbing layer (31) absorbs visible light.

[0011] A fifth invention is a marker (1E) according to the first invention, wherein the first reflective layer (20) and the partially disposed near-infrared light absorbing layer (30E) are directly or indirectly superimposed on each other, and the near-infrared light absorbing layer (30E) transmits visible light.

[0012] A sixth invention is a marker (1F) according to the first invention, in which the first reflective layer (20), a visible light absorbing near-infrared light transmitting layer (50F) that absorbs visible light and transmits near-infrared light, and the partially disposed near-infrared light absorbing layer (31F) are directly or indirectly stacked in this order, and the near-infrared light absorbing layer (31F) absorbs visible light.

[0013] A seventh invention is a marker (1, 1B, 1C, 1D, 1E, 1F) according to any one of the first to sixth inventions, wherein at least one of the first reflective layer (20) and the near-infrared light absorbing layer (30, 30E, 31, 31F) is made of a resist material.

[0014] The eighth invention is a marker (1, 1B, 1C, 1D, 1E, 1F) according to any one of the first to seventh inventions, further comprising a protective layer laminated thereon to protect the surface.

[0015] A ninth invention is the marker (1, 1B, 1C, 1D, 1E, 1F) according to the eighth invention, wherein the protective layer has an anti-reflection function.

[0016] A tenth aspect of the present invention is a marker (1, 1B, 1C, 1D, 1E, or 1F) according to any one of the first to ninth aspects of the present invention, wherein the linear expansion coefficient is 10×10 -6 The marker (1, 1B, 1C, 1D, 1E, 1F) is provided with a base layer (10) having a temperature of 100°C or lower.

[0017] An eleventh invention is the marker (1, 1B, 1C, 1D, 1E, 1F) according to the tenth invention, wherein the base material layer is made of glass.

[0018] The twelfth invention is a marker (1, 1B, 1C, 1D, 1E, 1F) according to any one of the first to eleventh inventions, characterized in that the marks (2) are three or more and arranged at intervals.

[0019] A thirteenth invention is a marker (1, 1B, 1C, 1D, 1E, 1F) according to the twelfth invention, in which a graphic (5) for identification is arranged.

[0020] A fourteenth invention is a marker (1, 1B, 1C, 1D, 1E, 1F) according to the thirteenth invention, in which the identification graphic (5) is any one of a two-dimensional barcode, a three-dimensional barcode, a QR code, and ArUco.

[0021] A fifteenth aspect of the present invention is a multi-faceted marker body (90) having a plurality of markers (1, 1B, 1C, 1D, 1E, 1F) according to any one of the first to fourteenth aspects of the present invention attached thereto. Effect of the Invention

[0022] According to the present invention, it is possible to provide a marker and a multi-faceted marker body that are inconspicuous to the human eye. [Brief description of the drawings]

[0023] [Figure 1] FIG. 1 is a diagram showing a marker 1 according to a first embodiment. [Diagram 2] 2 is a cross-sectional view of the marker taken along the line indicated by the arrow AA in FIG. 1. [Diagram 3] FIG. 1 is a diagram showing an experimental situation. [Figure 4] FIG. 1 is a diagram illustrating an experimental marker S. [Diagram 5] 1 is a graph showing the change in light transmittance according to wavelength for three types of CWO (CWO-1, CWO-2, CWO-3) and ITO alone. [Figure 6] FIG. 1 is a graph summarizing the results of photographing the experimental marker S and the comparative example. [Figure 7] FIG. 2 is a diagram showing a multi-faceted marker body 90. [Figure 8] 10 is a diagram showing an example in which the arrangement of near-infrared light reflection regions and absorption regions in the first embodiment is reversed. FIG. [Figure 9] FIG. 2 is a diagram showing a modified embodiment in which the position of the base layer 10 is changed in the first embodiment. [Figure 10] FIG. 11 is a diagram showing a modified form of the first embodiment that makes marks and the like less noticeable. [Figure 11] 3 is a cross-sectional view of a marker 1D according to a second embodiment taken at the same position as in FIG. 2. [Figure 12] 3 is a cross-sectional view of a marker 1E according to a third embodiment taken at the same position as in FIG. 2. [Figure 13] 10 is a cross-sectional view of a marker 1F according to a fourth embodiment taken at the same position as in FIG. 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings.

[0025] (First embodiment) FIG. 1 is a diagram showing a marker 1 according to the first embodiment. FIG. 2 is a cross-sectional view of the marker taken along the position of the arrow AA in FIG. Note that the figures shown below, including Figures 1 and 2, are schematic diagrams, and the size and shape of each part are exaggerated or omitted as appropriate to make them easier to understand. In the following description, specific numerical values, shapes, materials, etc. are given, but these can be changed as appropriate. In this specification, the terms plate, sheet, film, etc. are used, and in general usage, they are used in the order of thickness, plate, sheet, film, etc., and this specification follows that order. However, since such distinction in usage has no technical meaning, these terms can be used interchangeably as appropriate. In the present invention, the term "transparent" refers to a material that transmits at least light of a wavelength to be used. For example, even if a material does not transmit visible light, if it transmits infrared light, it is treated as transparent when used for infrared applications. In addition, the specific numerical values ​​specified in the present specification and claims should be treated as including a general margin of error. In other words, a difference of about ±10% means that there is no substantial difference, and values ​​set within a range slightly exceeding the numerical range of the present invention should be interpreted as being substantially within the scope of the present invention.

[0026] The marker 1 is configured in a plate shape that is substantially square when viewed from the normal direction of the surface as shown in FIG. 1, and a plurality of marks 2 are arranged. In this embodiment, the shape viewed from the surface side is formed into a substantially square shape of 60 mm x 60 mm, and a total of four circular marks 2 are arranged at intervals near each of the four corners of the marker 1. It is preferable that three or more marks 2 are arranged. This is because, for example, by calculating three center positions of gravity of the marks 2 from the observation results of the marks 2, the relative position, inclination, and attitude between the observation position (camera, etc.) and the marker 1 can be accurately detected. In addition, if the number of marks 2 is more than three, for example, when some marks 2 are not clearly observed due to some obstacle, position detection is possible from the observation results of the remaining marks 2. In addition, by using a plurality of marks 2, the accuracy of position detection can be improved.

[0027] Additionally, the marker 1 has an identification mark 5 provided in the center of its surface. The identification mark 5 is a pattern figure (figure for identification) that is associated with a specific meaning depending on the pattern and displays unique information by the pattern. For example, the identification mark 5 is associated with a unique number or alphabet for each different pattern. The identification mark 5 can be a two-dimensional barcode, a three-dimensional barcode, a QR code (registered trademark), ArUco, or the like. As described above, the identification mark 5 can be any of various known identification codes, but by using an identification mark 5 like the present embodiment in which the number of patterns is reduced to make the pattern larger, detection by a camera can be easily performed. As will be explained in more detail later, the areas of mark 2 and identification mark 5 shown in black in FIG. 1 are observed in the same color as the first reflective layer 20 on the surface under visible light, and can be identified as shown in FIG. 1 when photographed with a camera sensitive to near-infrared light.

[0028] The marker 1 can be attached to a wall surface or the like in a living space such as a room, and used for controlling the automatic driving of an automatic driving robot equipped with a camera. That is, the relative positional relationship between the wall surface or the like and the automatic driving robot can be accurately grasped from the photographing result by the camera, and the operation of the automatic driving robot can be controlled based on the relative positional relationship. For such applications, the dimensions of the marker 1 as viewed from the front side are preferably 100 mm x 100 mm or less, but according to the marker 1 of this embodiment, even with such a small size, it is possible to perform very high-precision position detection. The external dimensions of the marker 1 are not limited to the above example, and can be changed as appropriate, for example, to 10 mm×10 mm, 20 mm×20 mm, 40 mm×40 mm, 44 mm×44 mm, 80 mm×80 mm, etc.

[0029] In addition, in this embodiment, the mark 2 is configured to have a circular shape, but it is not limited to a circular shape, and may be a polygonal shape such as a triangle or a rectangle, or may be another shape. The marker 1 is used to detect the relative positional relationship between the shooting position and the marker 1 (hereinafter, also simply referred to as position detection) depending on how the mark 2 is observed.

[0030] The marker 1 is configured as a thin plate-like structure in which a base layer 10, a second reflective layer 40, a near-infrared light absorbing layer 30, and a first reflective layer 20 are stacked in this order from the back side (the lower side in FIG. 2, which is the side opposite to the observation side). In the present specification and claims, the terms "stacked" and "laminated" do not only mean directly stacked, but also include indirectly stacked with other layers having various functions provided between them. The upper side in FIG. 2 is the observation side (front side).

[0031] The base layer 10 is made of a glass plate. By making the base layer 10 of a glass plate, it is possible to prevent the marker 1 from expanding and contracting due to temperature changes and moisture absorption. The linear expansion coefficient of a glass plate is, for example, 31.7×10 -7 / ℃, and dimensional change due to temperature change is very small. The linear expansion coefficient of ceramics is, for example, 28×10 -7 / °C, and dimensional change due to temperature change is very small, similar to glass. Therefore, ceramics may be used for the base layer. In order to suppress dimensional change due to temperature change, the base layer 10 has a linear expansion coefficient of 10×10 -6 It is desirable that the temperature be below 100°C. The thickness of the base material layer 10 is preferably 0.3 mm or more and 2.3 mm or less. If the thickness of the base material layer 10 is less than 0.3 mm, it will break during cutting and additional processing will not be possible, and if the thickness is more than 2.3 mm, the weight will be too large to handle when it is made into a multi-sided marker body as described below.

[0032] The first reflective layer 20 is a reflective layer that reflects visible light (light having a wavelength of 360 nm or more and less than 780 nm) and near-infrared light (light having a wavelength of 780 nm or more and less than 2500 nm). The first reflective layer 20 is partially missing from the near-infrared light absorbing layer 30, and is partially disposed on the near-infrared light absorbing layer 30. The first reflective layer 20 reflects visible light, is colored white in visible light, and is formed of a resist material that also reflects near-infrared light. In the description of this specification and the claims, the term "resist material" refers to a resin composition material having photosensitivity that contains a pigment or dye. The resist material constituting the first reflective layer 20 of this embodiment is a resist material in a state after losing photosensitivity as a result of performing a development process on a resist material having photosensitivity used in a photolithography process. Examples of the resist material used for the first reflective layer 20 include PMMA, ETA, HETA, HEMA, and mixtures with epoxy. Examples of materials that can be colored white include titanium oxide, zirconia, and barium titanate. In the first reflective layer 20, openings 20a are provided corresponding to the regions of the mark 2 and the identification mark 5 shown in black in FIG. 1, which are partially opened by photolithography to expose the near-infrared light absorption layer 30. That is, the first reflective layer 20 partially conceals the near-infrared light absorption layer 30, and the unconcealed regions (regions where the first reflective layer 20 is not laminated) are the openings 20a. The regions of the near-infrared light absorption layer 30 visualized by the openings 20a are configured to be observable as the mark 2 and the identification mark 5 having independent shapes. Note that the marks having independent shapes refer to a form in which a plurality of marks are not connected and each can be individually recognized.

[0033] The thickness of the first reflective layer 20 is desirably 3 μm or more. If the thickness of the first reflective layer 20 is thinner than 3 μm, the back side is visible through the layer, the contrast is reduced, and the visibility of the mark 2 (ease of detection by automatic recognition) is reduced.

[0034] The near-infrared light absorbing layer 30 absorbs near-infrared light and transmits visible light. The near-infrared light absorbing layer 30 of this embodiment is formed on the entire surface of the second reflective layer 40. In FIG. 2, the arrows shown by solid lines indicate visible light, and the arrows shown by dashed lines indicate near-infrared light (similar to the figures of other embodiments). As shown in FIG. 2, visible light that reaches the near-infrared light absorbing layer 30 from the observation side is reflected back to the observation side, but near-infrared light is absorbed by the near-infrared light absorbing layer 30 and is not reflected back to the observation side. The near-infrared light absorption layer 30 is formed of a resist material that absorbs near-infrared light and transmits visible light. The resist material constituting the near-infrared light absorption layer 30 of this embodiment is a resist material that has lost its photosensitivity as a result of performing a development process on a photosensitive resist material used in a photolithography process. Examples of resist materials used for the near-infrared light absorption layer 30 include PMMA, ETA, HETA, HEMA, and mixtures with epoxy. The near-infrared light absorption layer 30 is transparent to visible light because it transmits visible light, but is composed of a resist material into which a near-infrared absorbing material is kneaded in order to absorb near-infrared light. Examples of near-infrared absorbing materials that can be used for the near-infrared light absorbing layer 30 of the first embodiment include cesium tungsten oxide (CWO (registered trademark) manufactured by Sumitomo Metal Mining Co., Ltd.), lanthanum hexaboride (LaB6), OPTLION (registered trademark) manufactured by Toyo Visual Solutions Co., Ltd., and materials described in Japanese Patent No. 6857296.

[0035] The second reflective layer 40 is a reflective layer that reflects visible light and near-infrared light. The second reflective layer 40 is disposed on the entire surface of the observation side of the base layer 10. Moreover, the second reflective layer 40 can be formed using the same material as that forming the first reflective layer 20.

[0036] 2, the visible light indicated by the solid line is reflected by the surface of the first reflective layer 20 and returns to the observation side. In addition, in the opening 20a, the visible light passes through the near-infrared light absorbing layer 30 and is reflected by the second reflective layer 40 and returns to the observation side. Therefore, there is almost no difference in the visible light returning to the observation side between the opening 20a and other areas, and both areas are observed to be white, which is the color of the first reflective layer 20 and the second reflective layer 40 under visible light, and the mark 2 and the identification mark 5 are difficult to visually recognize. On the other hand, the near-infrared light indicated by the dashed line in Fig. 2 is reflected by the surface of the first reflective layer 20 and returns to the observation side. However, in the opening 20a, the near-infrared light is absorbed by the near-infrared light absorption layer 30 and does not return to the observation side. Therefore, there is a large difference in the amount of near-infrared light that returns to the observation side between the opening 20a and other areas. This makes it easy to distinguish the mark 2 and the identification mark 5 when photographed with a camera sensitive to near-infrared light. 1, the areas of mark 2 and identification mark 5 shown in black are observed in visible light as white, the same color as the surface first reflective layer 20. On the other hand, when photographed with a camera sensitive to near-infrared light, they are identifiable as shown in Fig. 1, and when areas in the photographed image where the near-infrared light intensity is high are shown in white and areas where the near-infrared light intensity is low are shown in black, the image photographed using near-infrared light will be as shown in Fig. 1.

[0037] In addition to the above layer structure, a protective layer for further protecting the surface may be provided on the observation side. The protective layer may be composed of, for example, a resin substrate layer and a surface layer. The resin substrate layer may be composed of, for example, vinyl chloride, polyethylene terephthalate, polycarbonate, cycloolefin polymer, triacetyl cellulose, etc. The surface layer may be composed of, for example, an acrylic resin, sol-gel, siloxane, polysilazane, etc., which has a property of diffusing light by mixing fine particles, but if the surface of the resin substrate layer is embossed to give it a property of diffusing light by making the surface shape uneven, the surface layer may be omitted. By adding a light diffusion function to the protective layer as described above, it is possible to have a function as a light diffusion layer. In addition, an anti-reflection function may be provided on the surface layer. In addition, it is preferable to configure the protective layer to be placed on the first reflective layer 20 by an adhesive layer.

[0038] An experimental marker having a similar configuration to the marker 1 of the first embodiment was created and a demonstration experiment was carried out, which will be described below. FIG. 3 is a diagram showing the experimental situation. Illumination light including near-infrared light is irradiated from a light source L onto the experimental marker S. As the light source L, an L-709 LED light (infrared specification) manufactured by Hozan Corporation was used. In addition, the experimental marker S is photographed by an infrared camera CA. The infrared camera CA used was an L-834 USB camera (infrared specification) manufactured by Hozan Corporation.

[0039] FIG. 4 is a diagram illustrating the experimental marker S. The experimental marker S has six rectangular marks S2 arranged side by side, which correspond to the marks 2 of the marker 1. The marks S2 have a wide spaced portion in the center. The layer structure of the experimental marker S was the same as that of the marker 1 shown in FIG. 1. However, three types of experimental markers S were prepared, each made using three types of CWO (CWO-1, CWO-2, CWO-3) with different light transmittances as the near-infrared absorbing material of the near-infrared light absorbing layer 30. Furthermore, as a comparative example, a marker in which ITO (Indium Tin Oxide) was arranged in the near-infrared light absorbing layer 30 was prepared. FIG. 5 is a graph showing the change in light transmittance with wavelength for each of three types of CWO (CWO-1, CWO-2, CWO-3) and ITO alone. In addition, the light transmittance at a wavelength of 940 nm for the three types of CWO and ITO is 32% for CWO-1, 6.9% for CWO-2, 1.1% for CWO-3, and 46% for ITO.

[0040] Fig. 6 is a graph summarizing the results of photographing the experimental marker S and the comparative example. In Fig. 6, the vertical axis indicates the intensity of the output signal corresponding to the amount of light received per pixel in the image photographed by the infrared camera CA, and the horizontal axis indicates the distance in the direction of the arrow SX in Fig. 4. As shown in Fig. 6, for all of CWO-1, CWO-2, and CWO-3, the intensity changes sharply in response to the mark S2, and it was confirmed that the mark S2 is easily identifiable. In contrast, although the intensity distribution of ITO shows slight undulations in response to the position of the mark S2, the intensity change is not steep, and it can be determined that it is not suitable for identifying the mark S2. From this result, it can be determined that the light transmittance at a wavelength of 940 nm of 40% or less is desirable for the near-infrared light absorption layer 30.

[0041] FIG. 7 is a diagram showing a multi-faceted marker body 90. As shown in FIG. The marker 1 is manufactured by arranging a plurality of markers 1 side by side, that is, by manufacturing a multi-faceted marker body 90 having a plurality of markers 1 attached thereto. The markers 1 are then obtained by cutting out individual markers 1 from the multi-faceted marker body 90. Note that, although FIG. 7 shows an example in which all the identification marks 5 have the same shape, the shapes of the identification marks 5 may each have a different shape.

[0042] FIG. 8 is a diagram showing an example in which the arrangement of the near-infrared light reflective region and absorptive region in the first embodiment is reversed. As shown in Figure 8, the arrangement of the near-infrared light reflection region (region shown in white) and absorption region (region shown in black) in Figure 1 may be reversed. Even if reversed as in Figure 8, the whole is observed as white under visible light, and marks and the like are not noticeable.

[0043] FIG. 9 is a diagram showing a modified embodiment in which the position of the base layer 10 is changed in the first embodiment. The position of the base material layer 10 can be changed as appropriate, and in the example of the marker 1B shown in FIG. 9, the base material layer 10 is disposed between the near-infrared light absorbing layer 30 and the first reflective layer 20. The base material layer 10 may also be disposed between the second reflective layer 40 and the near-infrared light absorbing layer 30. Note that such a change in the position of the base material layer 10 can be similarly performed in other embodiments and modified forms described below.

[0044] FIG. 10 is a diagram showing a modified form of the first embodiment in which marks and the like are made less noticeable. The first reflective layer 20C of the marker 1C shown in FIG. 10 contains a dye or pigment that approximates the color of visible light reflected by the first reflective layer 20 through the near-infrared light absorbing layer 30 and returning to the observation side. The near-infrared absorbing material contained in the near-infrared light absorbing layer 30 transmits visible light and is therefore not colored by the visible light, but depending on the near-infrared absorbing material used, it may have a certain degree of light absorbing effect on visible light and may color the visible light. In this case, for example, the mark 2 may be observed as a pale transparent blue or pale transparent yellow under visible light. In such a case, it is possible to make the mark 2 and the identification mark 5 even less noticeable by including a dye or pigment in the first reflective layer 20C to approximate the color of the visible light reflected by the second reflective layer 40 through the near-infrared light absorbing layer 30 and returning to the observation side.

[0045] As described above, according to the first embodiment, the markers 1, 1B, and 1C are provided with the near-infrared light absorbing layer 30. Therefore, the markers 1, 1B, and 1C can be made so that the mark 2 and the identification mark 5 are barely distinguishable under visible light, and can be made so that the mark 2 and the identification mark 5 can be properly distinguished when observed with near-infrared light.

[0046] Second embodiment FIG. 11 is a cross-sectional view of a marker 1D of the second embodiment taken at the same position as in FIG. The marker 1D of the second embodiment has a similar structure to the marker 1 of the first embodiment, except for a part of the layer structure. Therefore, the same reference numerals are used for parts that perform the same functions as those of the first embodiment described above, and duplicated explanations will be omitted as appropriate. The marker 1D of the second embodiment is configured as a thin plate by stacking a base layer 10, a first reflective layer 20, a near-infrared light absorbing layer 31, and a visible light absorbing near-infrared light transmitting layer 50 in this order from the back surface side.

[0047] The base material layer 10 and the first reflective layer 20 are layers similar to the base material layer 10 and the first reflective layer 20 of the marker 1 of the first embodiment. The first reflective layer 20 of the present embodiment is provided on the entire surface of the base material layer 10.

[0048] The near-infrared light absorption layer 31 is partially missing from the first reflective layer 20, and is partially arranged in a shape that is observed as the mark 2 and the identification mark 5 when observed with near-infrared light (the shape of the region shown in black in FIG. 1). The near-infrared light absorption layer 31 of the second embodiment is configured to absorb visible light as well, unlike the near-infrared light absorption layer 30 of the first embodiment. The near-infrared light absorbing layer 31 of the second embodiment is also formed of a resist material like the near-infrared light absorbing layer 30 of the first embodiment, but the near-infrared light absorbing material kneaded into the resist material is different from that of the near-infrared light absorbing layer 30 of the first embodiment. Examples of near-infrared absorbing materials that can be used in the near-infrared light absorbing layer 31 of the second embodiment include carbon, blackened titanium, nickel oxide, etc. From the viewpoint of high light absorptivity and dispersion in resin, when using a resist material in which carbon black is dispersed in resin, for example, the carbon black is preferably 30% by weight or more and 50% by weight or less.

[0049] The visible light absorbing near-infrared light transmitting layer 50 is adjacent to the near-infrared light absorbing layer 31 at the same level as the layer in which the near-infrared light absorbing layer 31 is disposed, and is disposed in a portion in which the near-infrared light absorbing layer 31 is not disposed. That is, the visible light absorbing near-infrared light transmitting layer 50 is aligned with the near-infrared light absorbing layer 31 and fills the region other than the visible light absorbing near-infrared light transmitting layer 50. Moreover, the visible light absorbing near infrared light transmitting layer 50 absorbs visible light and transmits near infrared light. The visible light absorbing near-infrared light transmitting layer 50 is also formed of a resist material like the near-infrared light absorbing layer 31, but the material for adjusting transmitted light kneaded into the resist material is different. Examples of the material for adjusting transmitted light kneaded into the resist material in the visible light absorbing near-infrared light transmitting layer 50 include the materials described in JP 2019-207303 A.

[0050] 11, the visible light indicated by the solid line is absorbed in the near-infrared light absorbing layer 31. Visible light is also absorbed in the visible light absorbing near-infrared light transmitting layer 50 and does not return to the observation side. Therefore, with visible light, the marker 1D of the second embodiment is observed to be entirely black, and the mark 2 and the identification mark 5 are difficult to visually recognize. On the other hand, the near-infrared light indicated by the dashed dotted line in Fig. 11 is absorbed by the near-infrared light absorbing layer 31 and does not return to the observation side. However, in the visible light absorbing near-infrared light transmitting layer 50, the near-infrared light transmits and is reflected by the first reflective layer 20, returning to the observation side. Therefore, for near-infrared light, there is a large difference in the amount of light that returns to the observation side between the near-infrared light absorbing layer 31 and the visible light absorbing near-infrared light transmitting layer 50. As a result, the mark 2 and the identification mark 5 can be easily identified by photographing them with a camera sensitive to near-infrared light. Therefore, the areas of the mark 2 and the identification mark 5 shown in black in Fig. 1 are both observed as black in visible light. On the other hand, when photographed with a camera sensitive to near-infrared light, they are distinguishable as shown in Fig. 1, and when areas in the photographed image where the intensity of near-infrared light is high are shown in white and areas where the intensity of near-infrared light is low are shown in black, the photographed image is taken using near-infrared light as shown in Fig. 1.

[0051] As described above, according to the marker 1D of the second embodiment, it is possible to achieve the same effects as the marker 1 of the first embodiment with a different configuration.

[0052] Third embodiment FIG. 12 is a cross-sectional view of a marker 1E of the third embodiment taken at the same position as in FIG. The marker 1E of the third embodiment has a similar structure to the marker 1 of the first embodiment, except for a part of the layer structure. Therefore, the same reference numerals are given to parts that perform the same functions as those of the first embodiment described above, and duplicated explanations will be omitted as appropriate. The marker 1E of the third embodiment is configured in the form of a thin plate by stacking a base layer 10, a first reflective layer 20, and a near-infrared light absorbing layer 30E in this order from the back surface side.

[0053] The base material layer 10 and the first reflective layer 20 are layers similar to the base material layer 10 and the first reflective layer 20 of the marker 1 of the first embodiment. The first reflective layer 20 of the present embodiment is provided on the entire surface of the base material layer 10.

[0054] The near-infrared light absorption layer 30E is partially missing from the first reflective layer 20, and is partially arranged in a shape that is observed as a mark 2 and an identification mark 5 when observed with near-infrared light (the shape of the region shown in black in FIG. 1). The near-infrared light absorption layer 30E of the second embodiment is configured to transmit visible light, similar to the near-infrared light absorption layer 30 of the first embodiment. Therefore, the near-infrared light absorption layer 30E of the third embodiment can use the same material as the near-infrared light absorption layer 30 of the first embodiment.

[0055] 12, visible light indicated by a solid line is reflected by the first reflective layer 20 and returns to the observation side. Also, visible light passes through the near-infrared light absorbing layer 30E, is reflected by the first reflective layer 20 and returns to the observation side. Therefore, with visible light, the marker 1E of the third embodiment is observed to be entirely white, and the mark 2 and the identification mark 5 are difficult to visually recognize. On the other hand, the near-infrared light indicated by the dashed line in Fig. 12 is reflected by the first reflective layer 20 and returns to the observation side. However, in the near-infrared light absorption layer 30E, the near-infrared light is absorbed and does not return to the observation side. Therefore, for near-infrared light, there is a large difference in the amount of light that returns to the observation side between the first reflective layer 20 and the near-infrared light absorption layer 30E. As a result, if an image is taken with a camera sensitive to near-infrared light, the mark 2 and the identification mark 5 can be easily identified. Therefore, the areas of the mark 2 and the identification mark 5 shown in black in Fig. 1 are both observed as white in visible light. On the other hand, when photographed with a camera sensitive to near-infrared light, they are distinguishable as shown in Fig. 1, and when areas in the photographed image where the intensity of near-infrared light is high are shown in white and areas where the intensity of near-infrared light is low are shown in black, the photographed image is taken using near-infrared light as shown in Fig. 1.

[0056] As described above, according to the marker 1E of the third embodiment, it is possible to achieve the same effects as the marker 1 of the first embodiment with a different configuration.

[0057] (Fourth embodiment) FIG. 13 is a cross-sectional view of a marker 1F of the fourth embodiment taken at the same position as in FIG. The marker 1F of the fourth embodiment has a similar structure to the marker 1 of the first embodiment, except for a part of the layer structure. Therefore, the same reference numerals are given to parts that perform the same functions as those of the first embodiment described above, and duplicated explanations will be omitted as appropriate. The marker 1F of the fourth embodiment is configured as a thin plate by stacking a base layer 10, a first reflective layer 20, a visible light absorbing near-infrared light transmitting layer 50F, and a near-infrared light absorbing layer 31F in this order from the back surface side.

[0058] The base material layer 10 and the first reflective layer 20 are layers similar to the base material layer 10 and the first reflective layer 20 of the marker 1 of the first embodiment. The first reflective layer 20 of the present embodiment is provided on the entire surface of the base material layer 10.

[0059] The visible light absorbing near-infrared light transmitting layer 50F is disposed so as to overlap the entire surface of the observation side of the first reflective layer 20. The visible light absorbing near-infrared light transmitting layer 50F is a layer that absorbs visible light and transmits near-infrared light. Therefore, the visible light absorbing near infrared light transmitting layer 50F of the fourth embodiment can use the same material as the visible light absorbing near infrared light transmitting layer 50 of the second embodiment.

[0060] The near-infrared light absorption layer 31F is partially missing from the first reflective layer 20, and is partially arranged in a shape that is observed as the mark 2 and the identification mark 5 when observed with near-infrared light (the shape of the area shown in black in FIG. 1). The near-infrared light absorption layer 31F of the fourth embodiment is configured to absorb not only near-infrared light but also visible light. Therefore, the near-infrared light absorption layer 31F of the fourth embodiment can use the same material as the near-infrared light absorption layer 31 of the second embodiment.

[0061] 13, the visible light indicated by the solid line is absorbed in the near-infrared light absorbing layer 31F. Also, the visible light is absorbed in the visible light absorbing near-infrared light transmitting layer 50F and does not return to the observation side. Therefore, with visible light, the marker 1F of the fourth embodiment is observed to be entirely black, and the mark 2 and the identification mark 5 are difficult to visually recognize. On the other hand, the near-infrared light indicated by the dashed line in Fig. 13 is absorbed by the near-infrared light absorbing layer 31 and does not return to the observation side. However, in the visible light absorbing near-infrared light transmitting layer 50F, the near-infrared light is transmitted and reflected by the first reflective layer 20, returning to the observation side. Therefore, for near-infrared light, there is a large difference in the amount of light that returns to the observation side between the near-infrared light absorbing layer 31F and the visible light absorbing near-infrared light transmitting layer 50F. This makes it easy to distinguish the mark 2 and the identification mark 5 when photographed with a camera sensitive to near-infrared light. Therefore, the areas of the mark 2 and the identification mark 5 shown in black in Fig. 1 are both observed as black in visible light. On the other hand, when photographed with a camera sensitive to near-infrared light, they are distinguishable as shown in Fig. 1, and when areas in the photographed image where the intensity of near-infrared light is high are shown in white and areas where the intensity of near-infrared light is low are shown in black, the photographed image is taken using near-infrared light as shown in Fig. 1.

[0062] As described above, according to the marker 1E of the third embodiment, it is possible to achieve the same effects as the marker 1 of the first embodiment with a different configuration.

[0063] (Variations) The present invention is not limited to the above-described embodiment, and various modifications and variations are possible, and these are also within the scope of the present invention.

[0064] (1) In each embodiment, an example of a marker provided with the mark 2 and the identification mark 5 has been described. However, the present invention is not limited to this, and for example, the identification mark 5 may be omitted and only the mark 2 may be provided.

[0065] (2) In each embodiment, an example has been described in which both the mark 2 and the identification mark 5 are formed with the same layer structure using a resist material. However, the present invention is not limited to this, and for example, the identification mark 5 may be printed on the outermost surface. In this case, it is easy to create different identification marks 5 each representing a large number of unique information.

[0066] (3) In each embodiment, the reflective layer and near-infrared light absorbing layer for controlling transmitted light are formed from a resist material. However, the present invention is not limited to this. For example, a part or all of the reflective layer and near-infrared light absorbing layer may be formed as a reflective layer and near-infrared light absorbing layer using a resin other than the resist material as a binder.

[0067] (4) In each embodiment, the markers are shown to be white or black under visible light. However, the markers may be colored chromatically by adding various dyes or pigments to each layer. In this case, the markers can be made less noticeable by blending them with the color of the wallpaper when placed in a living space.

[0068] (5) In the second to fourth embodiments, an example has been described in which the base layer 10 is disposed on the back surface side. However, the present invention is not limited to this example, and the base layer 10 may be disposed between other layers, as exemplified in the first embodiment.

[0069] The embodiments and modifications may be used in appropriate combination, but detailed description thereof will be omitted. The present invention is not limited to the embodiments described above. [Explanation of symbols]

[0070] 1, 1B, 1C, 1D, 1E, 1F markers 2 Mark 5 Identification Mark 10 Base material layer 20, 20C 1st reflective layer 20a opening 28 Coefficient of linear expansion 30, 30E, 31, 31F Near infrared light absorbing layer 40 Second reflective layer 50, 50F Visible light absorbing near infrared light transmitting layer 90 Marker Polyhedral Body

Claims

1. a first reflective layer that reflects visible light and near infrared light; a near-infrared light absorbing layer that absorbs at least near-infrared light; are arranged in layers, one of the first reflective layer and the near-infrared light absorbing layer is made of a resist material having a partial opening and is partially missing from the other, A marker comprising a mark that is displayed as an independent shape by near-infrared light reflected by a layer other than the near-infrared light absorbing layer.

2. A first reflective layer that reflects visible light and near infrared light; a near-infrared light absorbing layer that absorbs at least near-infrared light; are arranged in layers, one of the first reflective layer and the near-infrared light absorbing layer is partially missing from the other, a mark that is displayed as an independent shape by near-infrared light reflected by a layer other than the near-infrared light absorbing layer; the first reflective layer disposed partially thereon; The near-infrared light absorbing layer; a second reflective layer that reflects visible light and near infrared light; are directly or indirectly stacked in this order, The near-infrared light absorbing layer transmits visible light, A marker, wherein the first reflective layer contains a dye or pigment that approximates the color of visible light reflected back by the second reflective layer through the near infrared light absorbing layer.

3. 2. The marker of claim 1 , the first reflective layer disposed partially thereon; The near-infrared light absorbing layer; a second reflective layer that reflects visible light and near infrared light; are directly or indirectly stacked in this order, A marker, wherein the near-infrared light absorbing layer transmits visible light.

4. The marker according to claim 1 or 2, the first reflective layer; the near infrared light absorbing layer being partially disposed; a visible light absorbing and near infrared light transmitting layer that is disposed adjacent to the near infrared light absorbing layer at the same level as the layer in which the near infrared light absorbing layer is disposed, in a portion in which the near infrared light absorbing layer is not disposed, and that absorbs visible light and transmits near infrared light; are directly or indirectly stacked in this order, A marker, wherein the near-infrared light absorbing layer absorbs visible light.

5. The marker according to claim 1 or 2, the first reflective layer; the near infrared light absorbing layer being partially disposed; are directly or indirectly arranged one on top of the other, A marker, wherein the near-infrared light absorbing layer transmits visible light.

6. The marker according to claim 1 or 2, the first reflective layer; a visible light absorbing near infrared light transmitting layer that absorbs visible light and transmits near infrared light; the near infrared light absorbing layer being partially disposed; are directly or indirectly stacked in this order, A marker, wherein the near-infrared light absorbing layer absorbs visible light.

7. The marker according to any one of claims 1 to 6, A marker with an additional protective layer to protect the surface.

8. The marker of claim 7, The protective layer has an anti-reflective function.

9. The marker according to any one of claims 1 to 8, Linear expansion coefficient is 10 x 10 －６ A marker comprising a base layer having a temperature of 0.1°C or lower.

10. 10. The marker of claim 9, A marker, wherein the base layer is made of glass.

11. The marker according to any one of claims 1 to 10, The marks are arranged in a spaced arrangement of three or more marks; A marker characterized by:

12. 12. The marker of claim 11, A marker with a shape for identification.

13. 13. The marker of claim 12, The identification graphic may be a two-dimensional barcode, a three-dimensional barcode, a QR code, an ArUco code, A marker that is either

14. A multi-faceted marker body having a plurality of markers according to any one of claims 1 to 13 attached thereto.

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