Measurement System

Abstract

Provided is a measuring system with which it is easy to manufacture a marker, and which is capable of high precision measurement.　A marker 1 to be measured by a measuring system 500 is provided with a base material layer 10, a first layer 20 which is laminated onto one surface of the base material layer 10 and which is observed in a first color, and a second layer 30 which is partially laminated onto the first layer 20, is observed in a second color different from the first color, and partially conceals the first layer 20, wherein the first layer 20 is observable in a region in which the second layer 30 is not laminated, and the second layer 30 is formed by means of a resist material.

Description

[Technical Field]

[0001] The present invention relates to a measurement system. [Background technology]

[0002] Markers are attached to various objects to enable various automatic control devices to 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, a widely used example of such a marker is one in which marks are printed on paper because it is easy to create. However, 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.

[0003] Therefore, Patent Document 1 discloses a technique for realizing a highly accurate marker, in which holes are drilled into a metal plate by cutting and resin is embedded in the holes to create a marker. However, the technique disclosed in Patent Document 1 requires high precision in the machining process, which makes it very time-consuming to produce the marker, and there is also a limit to how much precision can be improved. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 5-312521 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide a measurement system that allows for easy manufacturing of markers and enables highly accurate measurements. [Means for solving the problem]

[0006] The present invention solves the above-mentioned problems by the following means: For ease of understanding, the following description will be given with reference to the corresponding embodiments of the present invention, but the present invention is not limited to these.

[0007] The first invention is a measurement system (500) including markers (1, 1B, 1C), an imaging unit (201) that images the markers (1, 1B, 1C), and a calculation unit (202) that uses an image of the markers (1, 1B, 1C) captured by the imaging unit (201) to calculate at least one of the relative positional relationship between the imaging unit (201) and the markers (1, 1B, 1C), the dimensions of an object in the vicinity of the markers (1, 1B, 1C) or the distance between designated positions, the distance between a plurality of the markers (1, 1B, 1C), and the attitude of the markers (1, 1B, 1C), The measuring system (500) includes a target (1, 1B, 1C) comprising a base layer (10), a first layer (20, 20C) laminated on the observation side of the base layer (10) and observed in a first color, and a second layer (30, 30C) partially laminated on the observation side of the first layer (20, 20C), observed in a second color different from the first color, and partially concealing the first layer (20, 20C), wherein the first layer (20, 20C) is observable in an area where the second layer (30, 30C) is not laminated, and the second layer (30, 30C) is made of a resist material.

[0008] A second invention is a measurement system (500) according to the first invention, characterized in that the first layer (20, 20C) is made of a resist material.

[0009] The third invention is a measurement system (500) including markers (1, 1B, 1C), an imaging unit (201) that images the markers (1, 1B, 1C), and a calculation unit (202) that uses an image of the markers (1, 1B, 1C) captured by the imaging unit (201) to calculate at least one of the relative positional relationship between the imaging unit (201) and the markers (1, 1B, 1C), the dimensions of an object near the markers (1, 1B, 1C) or the distance between designated positions, the distance between a plurality of the arranged markers (1, 1B, 1C), and the attitude of the markers (1, 1B, 1C). The marker (1, 1B, 1C) comprises a base layer (10), a first layer (20, 20C) laminated on the observation side of the base layer (10) and observed in a first color laminated on the entire surface of the base layer (10), and a second layer (30, 30C) partially laminated on the observation side of the first layer (20, 20C), observed in a second color different from the first color, and partially concealing the first layer (20, 20C), wherein the first layer (20, 20C) is observable in an area where the second layer (30, 30C) is not laminated, and the base layer (10) has a linear expansion coefficient of 10×10 -6 / °C or less.

[0010] A fourth invention is a measurement system (500) according to any one of the first to third inventions, characterized in that the substrate layer (10) is made of glass.

[0011] The fifth invention is a measurement system (500) according to any one of the first to fourth inventions, characterized in that one of the first layer (20, 20C) or the second layer (30, 30C) is observable as a mark (2) of an independent shape, and three or more of the marks (2) are arranged at intervals.

[0012] The sixth invention is a measurement system (500) according to the fifth invention, characterized in that a graphic (5) for identification is arranged, and the calculation unit (202) identifies the markers (1, 1B, 1C) by referring to the graphic (5).

[0013] A seventh invention is a measurement system (500) according to the sixth invention, characterized in that the calculation unit (202) performs a first calculation process to calculate at least one of the relative positional relationship between the photographing unit (201, 450) and the marker (1), the dimensions of an object or the distance between designated positions in the vicinity of the marker (1), the distance between multiple arranged markers (1), and the attitude of the marker (1) based on an image of the mark (2) included in the image of the marker (1), and a second calculation process to calculate at least one of the relative positional relationship between the photographing unit (201, 450) and the marker (1), the dimensions of an object or the distance between designated positions in the vicinity of the marker (1), the distance between multiple arranged markers (1), and the attitude of the marker (1) based on an image of the identification figure (5) included in the image of the marker (1).

[0014] The eighth invention is a measurement system (500) according to the seventh invention, characterized in that the calculation unit (202) outputs the calculation result of the first calculation process when the calculation can be performed appropriately by the first calculation process, and outputs the calculation result of the second calculation process when the calculation cannot be performed appropriately by the first calculation process.

[0015] A ninth invention is a measurement system (500) according to the eighth invention, characterized in that the calculation unit (202) performs the first calculation process and the second calculation process in parallel.

[0016] A tenth invention is a measurement system (500) according to any one of the first to third inventions, characterized in that it further comprises a control unit (203) that performs control based on the calculation results of the calculation unit (202).

[0017] An eleventh invention is a measurement method for the measurement system (500) according to any one of the first to third inventions, comprising the steps of: the photographing unit (201) photographing the markers (1, 1B, 1C); and the calculation unit (202) calculating, using the image of the markers (1, 1B, 1C) photographed by the photographing unit (201), at least one of the relative positional relationship between the photographing unit (201) and the markers (1, 1B, 1C), the dimensions of an object in the vicinity of the markers (1, 1B, 1C) or the distance between designated positions, the distance between a plurality of the arranged markers (1, 1B, 1C), and the attitude of the markers (1, 1B, 1C).

[0018] A twelfth invention is a program for the measurement system (500) according to any one of the first to third inventions, which causes a computer (202, 203) to execute the steps of: the photographing unit (201) photographing the markers (1, 1B, 1C); and the calculation unit (202) using the image of the markers (1, 1B, 1C) photographed by the photographing unit (201) to calculate at least one of the relative positional relationship between the photographing unit (201) and the markers (1, 1B, 1C), the dimensions of an object in the vicinity of the markers (1, 1B, 1C) or the distance between designated positions, the distance between a plurality of the arranged markers (1, 1B, 1C), and the attitude of the markers (1, 1B, 1C). [Effects of the Invention]

[0019] According to the present invention, it is possible to provide a marker that is easy to manufacture and has high accuracy. Furthermore, according to the present invention, a marker capable of displaying a bright moire pattern can be provided. Furthermore, according to the present invention, it is possible to provide a marker that is easily recognizable even in an environment where sunlight, illumination light, or the like hits the marker. [Brief explanation of the drawings]

[0020] [Figure 1] FIG. 1 is a diagram showing a marker 1 according to a first embodiment. [Figure 2] 2 is a cross-sectional view of the marker taken along the arrow AA in FIG. 1. [Figure 3] 1A to 1C are diagrams showing the manufacturing process of the marker 1. [Figure 4] 10A and 10B are partially enlarged views showing the results of photographing the mark 2 of this embodiment and the comparative example. [Figure 5] 10 is a diagram showing the change in light intensity with respect to the change in position at the boundary between the black of the first layer 20 and the white of the second layer 30. FIG. [Figure 6] FIG. 10 is a diagram showing a marker 1B according to a second embodiment. [Figure 7] FIG. 10 is a diagram showing a marker 1C according to a third embodiment. [Figure 8] 8 is a cross-sectional view of the marker taken along the arrow BB in FIG. 7. [Figure 9] 9 is a diagram showing a manufacturing process of the marker 1C. Note that Fig. 9 shows the front and back (top and bottom) reversed to Fig. 8. [Figure 10] FIG. 1 is a diagram showing a multi-faceted marker body 100. [Figure 11] FIG. 10 is a diagram showing a configuration in which an electrode layer 95 is provided. [Figure 12] FIG. 10 is a diagram showing a modified embodiment of the first embodiment in which the first layer 20 is white and the second layer 30 is black. [Figure 13] FIG. 10 is a diagram showing a modified embodiment of the first embodiment in which the first layer 20 is white and the second layer 30 is black. [Figure 14] FIG. 10 is a diagram showing a modified example of the third embodiment in which the first layer 20C is black and the second layer 30C is white. [Figure 15] FIG. 10 is a diagram showing a modified example of the third embodiment in which the first layer 20C is black and the second layer 30C is white. [Figure 16] 10 is a cross-sectional view showing a modified embodiment in which a planarizing layer 91 is provided in an opening 30a of a second layer 30 of the first embodiment. FIG. [Figure 17] FIG. 10 shows a fourth embodiment of a marker according to the present invention. [Figure 18] 18 is a cross-sectional view of the marker taken along the arrow AA in FIG. 17. [Figure 19] FIG. 10 is an enlarged view of the vicinity of a second pattern 43 for explaining the cause of the occurrence of unwanted moire. [Figure 20] 3A and 3B are diagrams illustrating details of a first pattern 23 and a second pattern 43. FIG. [Figure 21] FIG. 2 is a diagram showing the marker 1 as viewed from an oblique direction. [Figure 22] FIG. 10 shows a fifth embodiment of a marker according to the present invention. [Figure 23] 23 is a cross-sectional view of the marker taken along the arrow AA in FIG. 22. [Figure 24] 10 is a graph showing the effect of the light diffusion layer 80. [Figure 25] FIG. 2 is a diagram showing the marker 1 as viewed from an oblique direction. [Figure 26] FIG. 10 shows a modified embodiment in which the colors of the first layer 20 and the second layer 30 are swapped. [Figure 27] FIG. 10 shows a sixth embodiment of a marker according to the present invention. [Figure 28] FIG. 10 is a diagram showing a pallet P to which a marker 1 of a sixth embodiment is attached. [Figure 29] FIG. 10 is a diagram showing a measurement system 500 including a marker 1 according to a sixth embodiment. [Figure 30] 10 is a flowchart showing the flow of control operations of a forklift 200 using the measurement system 500 of this embodiment. [Figure 31] FIG. 10 shows a seventh embodiment of a marker according to the present invention. [Figure 32] FIG. 10 is a diagram showing a multi-faceted marker body 100 according to a seventh embodiment. [Figure 33] FIG. 13 is a diagram showing a pallet P to which a marker 1 of a seventh embodiment is attached. [Figure 34] FIG. 10 is a diagram showing a measurement system 500 including a marker 1 according to a seventh embodiment. [Figure 35] 10 is a flowchart showing the flow of control operations of a forklift 200 using the measurement system 500 of this embodiment. [Figure 36] FIG. 10 is a diagram showing a state in which part of the mark 2 is not properly photographed due to an obstacle. [Figure 37] FIG. 13 is a diagram showing a first modified example of the usage of the marker 1 of the seventh embodiment. [Figure 38] FIG. 13 is a diagram showing a second modified example of the usage of the marker 1 of the seventh embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0021] Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings. In the measurement system according to the present invention, the marker is photographed with a camera to accurately measure the relative positional relationship between the marker and the camera, and the shape of the marker is therefore important. Therefore, first, examples of specific shapes of the marker will be given in the following first to sixth embodiments, and then a measurement system including the marker 1 of the sixth embodiment will be described.

[0022] (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 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, but in general, these are used in order of thickness, that is, plate, sheet, film, and so on, and this specification follows suit. However, since there is no technical significance in this distinction, these terms can be used interchangeably as appropriate. In the present invention, "transparent" refers to a material that transmits at least light of the wavelength to be used. For example, even if a material does not transmit visible light, if it transmits infrared light, it will be treated as transparent when used in infrared applications. The specific numerical values ​​specified in the specification and claims should be treated as including a general margin of error. In other words, a difference of about ±10% is not substantially different, 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.

[0023] As shown in FIG. 1 , the marker 1 is configured as a plate with a substantially square shape when viewed from the normal direction of the surface on which the protective layer 70 (described later) is provided, and multiple marks 2 are arranged on the marker 1. In this embodiment, the marker 1 is formed into a substantially square shape (with chamfered corners) measuring 60 mm × 60 mm when viewed from the surface side, and a total of four circular marks 2 are arranged at intervals, one near each of the four corners of the marker 1. It is desirable to arrange at least three marks 2. This is because, for example, by calculating the three center-of-gravity positions of the marks 2 from the observation results of the marks 2, the relative position, tilt, and attitude between the observation position (camera, etc.) and the marker 1 can be accurately detected. Furthermore, if the number of marks 2 is more than three, for example, even if some of the marks 2 are obscured due to some obstacle, position detection is possible from the observation results of the remaining marks 2. Furthermore, using multiple marks 2 can improve the accuracy of position detection.

[0024] Marker 1 can be attached to the side of a measurement target, such as a pallet on which cargo is placed, and used for automatic operation control of a camera-equipped self-driving forklift or the like. That is, the relative positional relationship between the forklift and the pallet can be accurately determined from the results of photography by the camera, and the operation of the forklift can be controlled based on that relative positional relationship. For such applications, the dimensions of marker 1 as viewed from the front side are preferably 100 mm x 100 mm or less, but with marker 1 of this embodiment, even with such a small size, highly accurate position detection is possible. 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 x 10 mm, 20 mm x 20 mm, 40 mm x 40 mm, 44 mm x 44 mm, 80 mm x 80 mm, etc.

[0025] In addition, in this embodiment, the mark 2 is configured to have a circular shape, but 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 simply referred to as position detection) depending on how the mark 2 is observed.

[0026] The marker 1 is configured as a thin plate by laminating a base layer 10, a first layer 20, a second layer 30, an adhesive layer 60, and a protective layer 70 in this order from the back side. In this specification and claims, the term "laminated" does not only mean that the layers are directly stacked on top of each other, but also that the layers are stacked with another layer interposed therebetween. The upper side in FIG. 2 (the side on which the protective layer 70 is provided) is the observation side (front side).

[0027] 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 glass plate of the substrate layer used in this embodiment is Corning (registered trademark) EAGLE XG (registered trademark), and its linear expansion coefficient is 3.17 × 10 -6 / ℃. The linear expansion coefficient of the glass plate is measured in accordance with JIS R3102. The linear expansion coefficient of ceramics is, for example, 28 x 10 -7 / °C, and dimensional change due to temperature change is very small, similar to glass. Therefore, ceramics may be used for the substrate layer. In order to suppress dimensional change due to temperature change, the substrate layer 10 has a linear expansion coefficient of 10 × 10 -6 It is desirable that the temperature is not higher than 100°C. An example of a ceramic that can be used as the substrate layer is silicon nitride (linear expansion coefficient is 2.8 × 10 -6 / °C) can be exemplified. A specific example is Denka SN Plate (manufactured by Denka Co., Ltd.). Other examples of ceramics that can be used as the substrate layer include an alumina substrate (96% alumina (manufactured by Nikko Co., Ltd.)), an alumina zirconia substrate (manufactured by MARURA Co., Ltd.), an aluminum nitride substrate (manufactured by MARURA Co., Ltd.), etc. In the case of ceramics, the linear expansion coefficient is measured in accordance with JIS R1618. The thickness of the base layer 10 is preferably 0.3 mm or more and 2.3 mm or less. If the thickness of the base layer 10 is less than 0.3 mm, the layer will break during cutting and additional processing will be impossible, and if the thickness is more than 2.3 mm, the layer will be too heavy to transport when made into a multi-sided substrate as described below.

[0028] The first layer 20 is formed from a resist material colored black (first color), and is laminated on the entire surface of the base layer 10. In Fig. 2, hatching indicates black, and this also applies to the other cross-sectional views below. In the present specification and claims, the term "resist material" refers to a photosensitive resin composition material containing a pigment or dye. The resist material constituting the first layer 20 of this embodiment is a resist material used in a photolithography process that has lost its photosensitivity as a result of being developed. Examples of resist materials used for the first layer 20 (if black) include PMMA, ETA, HETA, HEMA, and mixtures with epoxy. Examples of materials that can be colored black include carbon, blackened titanium, and nickel oxide. In this embodiment, the first layer 20 is formed from a resist material, so the surface of the first layer 20 can be formed very smoothly, which is desirable as a base for forming the second layer 30 described below. Furthermore, when forming the second layer, an alignment mark (not shown) can be formed on the outer periphery of the first layer 20, which improves dimensional accuracy. The thickness of the first layer 20 (in the case of black) is preferably 1 μm or more and 5 μm or less. If the thickness of the first layer 20 is 1 μm or less, it cannot be formed uniformly, and if it is 5 μm or more, the curing reactivity of the resin with ultraviolet light is insufficient.

[0029] The second layer 30 is formed of a resist material colored white (second color) and is laminated on the first layer 20 with a partial opening. The resist material constituting the second layer 30 in this embodiment is a resist material that has lost its photosensitivity as a result of being developed into a photosensitive resist material used in a photolithography process. Examples of resist materials used for the second layer 30 (when white) include PMMA, ETA, HETA, HEMA, and mixtures with epoxy. Examples of materials that are colored white include titanium oxide, zirconia, and barium titanate. The second layer 30 has four openings 30a that are partially opened by a photolithography process described below to visualize the first layer 20. That is, the second layer 30 partially conceals the first layer 20, and the unconcealed areas (areas where the second layer 30 is not laminated) are the openings 30a. The areas of the first layer 20 that are visualized by these openings 30a are configured to be observable as marks 2 with independent shapes. Note that marks with independent shapes refer to multiple marks that are not connected and can be individually recognized.

[0030] The thickness of the second layer 30 (in the case of white) is preferably 3 μm or more and 100 μm or less. If the thickness of the second layer 30 is thinner than 3 μm, the underlying first layer 20 will be visible, reducing contrast and the visibility (ease of detection by automatic recognition) of the mark 2. Also, if the thickness of the second layer 30 is thicker than 100 μm, when the mark 2 is observed from an oblique direction, the area where the first layer 20 is hidden by the second layer 30 at the periphery of the opening 30 a will increase, resulting in increased distortion of the shape of the observed mark 2.

[0031] For more accurate detection, it is desirable for the mark 2 to have a high contrast value between the color of the first layer 20 and the color of the second layer 30. In the configuration of this embodiment used under white light (visible light), it is desirable that the contrast value between the color of the first layer 20 (first color) and the color of the second layer 30 (second color) is 0.26 or more, and that the blur value between the observed color of the first layer 20 (first color) and the color of the second layer 30 (second color) is 0.17 or more. The contrast value and blur value will be described later using FIG. 5.

[0032] The adhesive layer 60 is a layer of adhesive for attaching the protective layer 70 onto the second layer 30. The adhesive layer 60 is made of a transparent adhesive so that the first layer 20 and the second layer 30 can be observed. The adhesive layer 60 can be made of, for example, PMMA, urethane, silicone, etc. The thickness of the adhesive layer 60 is preferably 0.5 μm or more and 50 μm or less. If the thickness of the adhesive layer 60 is less than 0.5 μm, it is difficult to achieve uniform processing and it cannot absorb the unevenness of the underlying surface. If the thickness of the adhesive layer 60 is thicker than 50 μm, it takes time to remove the solvent during thick coating processing and the cost becomes high. Note that the thickness of the adhesive layer 60 here refers to the thickness at the thinnest position.

[0033] The protective layer 70 protects the first layer 20 and the second layer 30 and is attached to the second layer 30 via an adhesive layer 60. The protective layer 70 includes a resin substrate layer 71 and a surface layer 72. The resin substrate layer 71 can be made of, for example, vinyl chloride, polyethylene terephthalate, polycarbonate, cycloolefin polymer, triacetyl cellulose, or the like. The surface layer 72 can be made of, for example, an acrylic resin, sol-gel, siloxane, polysilazane, or the like, which has light-diffusing properties due to the inclusion of fine particles. However, if the surface of the resin substrate layer 71 is embossed or otherwise textured to impart light-diffusing properties, the surface layer 72 can be omitted. By adding a light-diffusing function to the protective layer 70 as described above, the protective layer 70 can also function as a light-diffusing layer.

[0034] The resin base material layer 71 has an adhesive layer 60 laminated on one surface thereof and a surface layer 72 laminated on the other surface thereof. The resin base material layer 71 is made of a transparent resin so that the first layer 20 and the second layer 30 can be observed. In this embodiment, it is assumed that the marker 1 will be used under visible light, and the adhesive layer 60 and the resin base material layer 71 are configured to be transparent to white light. Specifically, the adhesive layer 60 and the resin base material layer 71 each preferably have a total light transmittance of 50% or more in the light wavelength range of 400 nm to 700 nm. More preferably, when the adhesive layer 60 and the resin base material layer 71 are measured together, the total light transmittance in the light wavelength range of 400 nm to 700 nm is preferably 50% or more. The thickness of the resin substrate layer 71 is preferably 7 μm or more and 250 μm or less. This is because lamination processing is difficult if the thickness of the resin substrate layer 71 is less than 7 μm. On the other hand, if the thickness of the resin substrate layer 71 is greater than 250 μm, the layer becomes too bulky and heavy, and costs become high. The refractive index of the resin substrate layer 71 is preferably 1.45 or more and 1.55 or less.

[0035] The surface layer 72 may be a layer that combines anti-reflection and hard-coat functions. It is desirable for the surface layer 72 to have a specular reflectance of 1.5% or less for light with a wavelength of 535 nm to prevent a decrease in the visibility of the mark 2 due to reflection from the surface of the marker 1. For example, when using a ring-shaped light source or the like that surrounds the periphery of a camera lens to observe the marker 1, the light source itself may be reflected from the surface of the marker 1 and observed. In such cases, the anti-reflection function of the surface layer 72 prevents or suppresses surface reflection, allowing the outline of the mark 2 to be more clearly recognized and enabling highly accurate detection. Furthermore, it is desirable for the hard-coat function of the surface layer 72 to have a pencil hardness of 1H or higher. The surface layer 72 can be made of, for example, sol-gel, siloxane, polysilazane, or the like. Specific methods for anti-reflection include anti-reflection (AR) and anti-glare (AG), but the AR method is preferable for recognizing the mark 2 under conditions where strong light such as sunlight is not specularly reflected. The AG method is preferable for recognizing the mark 2 under conditions where strong light such as sunlight may be specularly reflected. The AR method can be produced by known methods such as multilayer thin film interference and moth-eye methods, and the AG method can be produced by known methods such as making the surface of the film uneven, incorporating light-diffusing particles into the film, or coating the surface of the film.

[0036] Furthermore, it is desirable that the total light transmittance be 85% or more as a combined characteristic of the adhesive layer 60 and the protective layer 70. If the total light transmittance is less than 85%, a sufficient amount of light cannot be ensured. Furthermore, as a combined characteristic of the adhesive layer 60 and the protective layer 70, it is desirable that the haze value be 30% or more, more preferably 40% or more, and even more preferably 70% or more. This is because the anti-reflection effect begins to decrease when the haze value is lower than 70%, decreases further when it is 40% or less, and decreases significantly when it is 30% or less. On the other hand, it is desirable that the haze value be 95% or less. This is because if the haze value is higher than 95%, the image of the mark observed will become blurred.

[0037] Next, a method for manufacturing the marker 1 of this embodiment will be described. 3A to 3C are diagrams showing the manufacturing process of the marker 1. Note that FIG. 3 shows the front and back (top and bottom) reversed to FIG. First, a glass plate is prepared as the substrate layer 10 (FIG. 3(a)). Next, a black-colored resist material, which will be the material for the first layer 20, is applied to one surface of the base layer 10 (first layer formation process), pre-baked, and then solidified. After that, it is exposed to a light source LS (first development process), and further developed and post-baked (first bake process) to stabilize the first layer 20 (Figure 3(b)).

[0038] Next, a white-colored resist material that will become the material for the second layer 30 is applied onto the first layer 20 (second layer forming step), and is pre-baked and solidified (FIG. 3(c)). Next, a mask M is brought into close contact with the solidified second layer 30, and a mark pattern is exposed onto the second layer 30 (second exposure step) (FIG. 3(d)). The mask M has a mask pattern formed in advance that transmits light except for the portion corresponding to the mark 2, and blocks light from the portion corresponding to the mark 2.

[0039] Next, the exposed second layer 30 is developed to remove the resist material at the positions corresponding to the marks 2, thereby forming openings 30a (second development step) (FIG. 3(e)). After development, the second layer 30 is post-baked (second bake step). Finally, a separately prepared film- or sheet-like protective layer 70 is attached onto the second layer 30 with the adhesive layer 60, completing the marker 1 (FIG. 3(f)).

[0040] The marker 1 of this embodiment uses a resist material, so the contour shape of the mark 2 can be created with extremely high precision, enabling even more precise control depending on the shape of the observed mark 2. To clearly demonstrate this fact, the contour shapes of the marker 1 of this embodiment and a comparative example were actually created, and the results of the comparison are shown below. In the comparative example, the shape of the mark 2 was printed on paper using a laser printer.

[0041] 4A and 4B are partially enlarged views of the results of photographing the marks 2 of this embodiment and a comparative example. Fig. 4A shows this embodiment, and Fig. 4B shows the comparative example. Note that Fig. 4 shows binarized images using an intermediate value between black and white as a threshold value. A digital microscope VHX-5500 (1 / 1.8-inch CMOS image sensor, effective pixels 1600 (H) × 1200 (V)) manufactured by Keyence Corporation was used to photograph Mark 2. The distance between Mark 2 and the tip of the lens during photography was 15 mm.

[0042] 4, in the marker 1 of this embodiment, the outline shape of the periphery of the mark 2 is expressed by a very smooth curve (arc). In contrast, in the comparative example, even though it looks like a circle from a distance, when enlarged, the outline shape is significantly different from an arc.

[0043] 4, the actual photographing results show that the comparative example has a significant presence of intermediate gradations rather than two gradations of black and white. Therefore, particularly in the comparative example, the shape perceived as the outer shape of the mark 2 is thought to change depending on the photographing conditions (observation conditions) and the method of distinguishing the boundary between black and white (threshold), which is undesirable. To make this easier to compare with the present embodiment, a graph was created based on the photographing data showing the change in light intensity with the change in position at the boundary between black and white.

[0044] FIG. 5 is a diagram showing the change in light intensity with respect to a change in position at the boundary between the black of the first layer 20 and the white of the second layer 30. In FIG. 5, lower intensity on the vertical axis appears to be on the black side, and higher intensity on the white side. The horizontal axis corresponds to the pixels of the captured data, but the reference position is shifted so that the two broken line data do not overlap, so the absolute value itself is meaningless. The change in pixel value on this horizontal axis corresponds to a change in position, with 100 pixels equivalent to 1 mm. The embodiment and comparative example in FIG. 5 are the same as the embodiment and comparative example shown in FIG. 4, respectively.

[0045] As explained above, it is desirable that the contrast value between the color of the first layer 20 (first color) and the color of the second layer 30 (second color) be 0.26 or greater. The reason why the contrast value is desirably 0.26 or more is that if the contrast value is less than 0.26, it is considered that automatic detection of the mark 2 using a camera will be difficult. Here, the contrast value is expressed as (Imax-Imin) / (Imax+Imin), where Imax is the maximum value of the light intensity and Imin is the minimum value. In the example shown in FIG. 5, the contrast value of this embodiment is 0.98, and the contrast value of the comparative example is 0.98, and no significant difference was observed between the two.

[0046] Furthermore, as explained above, it is desirable that the blur value between the observed color of the first layer 20 (first color) and the observed color of the second layer 30 (second color) be 1.0 or greater. In particular, when used for high-precision control, it is undesirable for the boundary of the mark to be unclear, so it is desirable that the intensity change at the boundary between the black side and the white side be rectangular or the change be steep. The intensity change at the boundary between the black side and the white side was quantified and compared from the data in FIG. 5 . Specifically, the data in the ranges indicated by LA and LB in the broken line in FIG. 5 was quantified using the slope. Here, the ranges LA and LB were determined as ranges that could be sufficiently approximated by a straight line. That is, an approximate straight line was obtained for the range where the intensity change was large, and the ranges LA and LB were the ranges where the measurement data did not deviate. Within the ranges LA and LB, the slope value of the intensity change (blur value) was calculated as (intensity change amount) / (pixel change amount). As a result, in this embodiment, the slope value of the intensity change (blur value) was 1.29. On the other hand, in the comparative example, the slope value of the intensity change (blur value) was 0.87. As such, a clear difference was observed between the two, and the configuration of this embodiment is more ideal and desirable.

[0047] As described above, according to this embodiment, photolithography is used, so that highly accurate machining is not required, and manufacturing is easy, and a highly accurate marker can be obtained. Furthermore, the marker 1 of this embodiment allows the thickness of the second layer 30 to be made very thin, which prevents the shape of the mark 2 from being distorted even when observed from an oblique direction, allowing for more accurate position detection.

[0048] (Second embodiment) FIG. 6 is a diagram showing a marker 1B of the second embodiment. The marker 1B of the second embodiment has the same configuration as the marker 1 of the first embodiment, except that it has more marks 2. Therefore, parts that perform the same functions as those in the first embodiment described above are given the same reference numerals, and redundant explanations will be omitted as appropriate.

[0049] The marker 1B of the second embodiment has more marks 2 arranged thereon than in the first embodiment. Specifically, nine marks 2 are arranged on the marker 1B at intervals in a grid pattern. As explained above, it is desirable to arrange at least three marks 2. This is because, for example, if three center of gravity positions of the marks 2 are calculated from the observation results of the marks 2, the relative position and inclination between the observation position (camera, etc.) and the marker 1 can be accurately detected. Furthermore, 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. Furthermore, by using multiple marks 2, the accuracy of position detection can be improved.

[0050] In the second embodiment, the number of marks 2 is set to nine, which is significantly more than in the first embodiment. As a result, in addition to the above effects, the following effects can be expected. For example, even if more than half of the area of ​​the marker 1B cannot be properly photographed (observed), and therefore there are many marks 2 that cannot be properly photographed (observed), the possibility of proper position detection can be increased by photographing (observing) the remaining marks 2. A situation in which more than half of the area of ​​the marker 1B cannot be properly photographed (observed) is, for example, a situation in which sunlight directly hits more than half of the area of ​​the marker 1B, and sunlight does not hit the remaining area. In such a case, if the exposure (gain) is adjusted appropriately for one side, the other side will be overexposed or underexposed. Another example is when another object physically overlaps part of the photographing optical axis, and more than half of the area of ​​the marker 1B cannot be photographed (observed).

[0051] Assuming that the markers are substantially square as shown in FIG. 6, it is desirable to have nine or more marks 2, as this makes it easier to arrange the marks 2 evenly. The number of marks 2 may be greater, and the arrangement is not limited to an even arrangement, but may be a so-called random arrangement, in which the marks 2 are arranged at random. Even in the case of a random arrangement, position detection can be easily performed as long as arrangement data of the marks 2 on the marker 1B is obtained. Furthermore, by using a random arrangement, it is possible to accurately grasp the relative positional relationship between the marker 1B and the shooting position (observation position) even if the relationship between the two is rotated by 180 degrees.

[0052] As described above, according to the second embodiment, the marker 1B has nine or more marks 2. Therefore, even under more severe photographing conditions (observation conditions), appropriate position detection is possible.

[0053] (Third embodiment) FIG. 7 is a diagram showing a marker 1C according to the third embodiment. FIG. 8 is a cross-sectional view of the marker taken along the arrow BB in FIG. The marker 1C of the third embodiment has the same observed marking form as the first embodiment, but has the same form as the marker 1 of the first embodiment, except that the first layer 20C is white and the second layer 30C on the observation side is black, that a planarizing layer 91 and an intermediate layer 92 are provided, and that the protective layer 70C has a different form. Therefore, parts that perform the same functions as in the first embodiment described above are given the same reference numerals, and redundant explanations will be omitted as appropriate.

[0054] The marker 1C of the third embodiment is configured as a thin plate by laminating a base layer 10, a first layer 20C, an intermediate layer 92, a second layer 30C, an adhesive layer 60, and a protective layer 70C in this order from the back side. A planarizing layer 91 is provided in the surrounding area where the second layer 30C is not provided.

[0055] The first layer 20C is formed of a resist material colored white (first color), and is laminated on the entire surface of the base material layer 10. In this embodiment, the base material layer 10 is made of alkali-free glass having a thickness of 700 μm. In this embodiment, the first layer 20C is formed from a resist material, which allows the surface of the first layer 20C to be formed very smoothly, making it desirable as a base for forming the second layer 30C described below. Also, when forming the second layer, an alignment mark (not shown) can be formed on the outer periphery of the first layer, improving dimensional accuracy. The thickness of the first layer 20C (in the case of white) is preferably 3 μm or more and 100 μm or less. If the thickness of the first layer 20C is thinner than 3 μm, the diffuse reflectance will be insufficient, the contrast will decrease, and the visibility of the mark 2 (ease of detection by automatic recognition) will decrease. Also, if the thickness of the first layer 20C is thicker than 100 μm, it will be difficult to make the film thickness uniform. In this embodiment, the thickness of the first layer 20C is 15 μm.

[0056] The second layer 30C is formed from a resist material that is colored black (second color). The second layer 30C is partially formed by a photolithography process described later, and four portions are provided to conceal the first layer 20C. The regions of the second layer 30C are configured to be observable as marks 2 having independent shapes.

[0057] The thickness of the second layer 30C is preferably 1 μm or more and 5 μm or less. If the thickness of the second layer 30C is 1 μm or less, it cannot be formed uniformly, and if it is 5 μm or more, the curing reactivity of the resin with ultraviolet light is insufficient. In the third embodiment, the second layer 30C is black, which provides high hiding power for the base. Therefore, the white color of the first layer 20C can be sufficiently hidden without increasing the thickness of the second layer 30C, making it possible to achieve the thin layer thickness described above. Furthermore, by forming the second layer 30C thin, it is possible to prevent a decrease in measurement accuracy due to the end face of the second layer 30C being observed, thereby improving measurement accuracy. In this embodiment, the thickness of the second layer 30C is 1 μm.

[0058] In the marker 1C of this embodiment, an intermediate layer 92 is laminated between the first layer 20C and the second layer 30C. The intermediate layer 92 is provided to resolve cases where the bonding strength between the first layer 20C and the second layer 30C is insufficient. If the second layer 30C is laminated directly on the first layer 20C, the second layer 30C may be repelled by the first layer 20C. In such cases, the provision of the intermediate layer 92, which is less likely to be repelled, allows the second layer 30C to be laminated appropriately. Therefore, the intermediate layer 92 may be provided as needed, or may be omitted as in the first embodiment. The intermediate layer 92 can be formed using, for example, acrylic resin, and a layer thickness of about 1 μm to 2 μm is sufficient. In this embodiment, the intermediate layer 92 is formed of acrylic resin with a thickness of 2 μm.

[0059] Since the first layer 20 or 20C is stacked on the base layer 10, and the second layer 30 or 30C is further stacked on top of that, steps are generated in the patterned second layer 30 or 30C. In the case of the second layer 30 of the first embodiment, the cross-sectional shape of the portion corresponding to the mark 2 is concave, and in the case of the second layer 30C of the third embodiment, the cross-sectional shape of the portion corresponding to the mark 2 is convex.

[0060] Therefore, when the protective layer 70 (described later) is attached, the adhesive layer 60 will fill the gap to some extent, but if the step is large, the adhesive layer will not be able to fill the gap, and an air gap (void) may form near the step. The refractive index of the air gap is 1, which is significantly lower than the refractive index of the substrate, which is approximately 1.4 to 1.6. This causes light to be reflected at the interface between the materials, resulting in disturbance light when the mark 2 is detected by the camera, significantly reducing detection accuracy. Therefore, to prevent the air gap from forming, the film thickness of the second layer 30, 30C is preferably 5 μm or less, more preferably 3 μm or less, and even more preferably 2 μm or less.

[0061] However, when the second layer 30 is white, as in the first embodiment described above, the hiding power of the base is inferior to that of black, so it may not be desirable to make it thinner, and there is a risk that the above-mentioned step will become larger. Therefore, if the above-mentioned step cannot be reduced to 5 μm or less, a planarizing layer 91 can be provided in the area surrounding the second layers 30, 30C where the second layers 30, 30C are not provided, to prevent the inclusion of an air layer. The planarizing layer 91 is preferably formed from a transparent material that allows the mark 2 to be identified, and known materials such as acrylic materials and epoxy materials can be used. The third embodiment illustrates an embodiment in which the above-mentioned step difference is reduced by providing a planarizing layer 91. By providing the planarizing layer 91, the step difference between the second layer 30C and the planarizing layer 91 can be further reduced. In the third embodiment, the second layer 30C is black, has high hiding power, and can be formed thin, so the planarizing layer 91 may be omitted.

[0062] The protective layer 70C is a layer that protects the first layer 20C and the second layer 30C, and is attached onto the second layer 30C and the planarizing layer 91 via an adhesive layer 60. In the third embodiment, the protective layer 70C is exemplified as a single layer, and specifically, a matte film made of vinyl chloride resin and having a haze value of 75 and a thickness of 70 μm is used.

[0063] Next, a method for manufacturing the marker 1C of this embodiment will be described. 9A to 9C are diagrams showing the manufacturing process of the marker 1C. Note that the front and back (top and bottom) of FIG. 9 are shown reversed to those of FIG. First, a glass plate is prepared as the base layer 10 (FIG. 9(a)). Next, a white-colored resist material, which will be the material for the first layer 20, is applied to one surface of the base layer 10 (first layer formation process), pre-baked, and dried, and then exposed to a light source LS (first development process), and further developed and post-baked (first bake process) to stabilize the first layer 20C (Figure 9(b)).

[0064] Next, an intermediate layer 92 is formed on the first layer 20C, and then a black-colored resist material that will become the material for the second layer 30C is applied on top of that (second layer formation process), followed by pre-baking and drying (Figure 9(c)). Next, a mask M is brought into close contact with the dried second layer 30C, and a mark pattern is exposed onto the second layer 30C (second exposure step) (FIG. 9(d)). The mask M has a mask pattern formed in advance that transmits light at positions corresponding to the marks 2 and blocks light in other areas.

[0065] Next, the exposed second layer 30C is developed to remove the resist material except for the portion corresponding to the mark 2 (around the mark 2), thereby forming an opening 30a (second development step) (FIG. 9(e)). After development, the second layer 30C is post-baked (second bake step). A planarization layer 91 is provided in the region where the second layer 30C is not formed (the region where the resist material has been removed). Finally, a separately prepared film- or sheet-like protective layer 70 is attached to the second layer 30C and the flattening layer 91 with the adhesive layer 60, completing the marker 1C (FIG. 9(f)).

[0066] FIG. 10 is a diagram showing a multi-faceted marker body 100. As shown in FIG. 9, the marker 1C is manufactured by arranging a plurality of markers 1C side by side, that is, by manufacturing a multi-faceted marker body 100 having a plurality of markers 1C attached thereto. Then, the markers 1C are obtained by cutting out and individualizing the individual markers 1C from the multi-faceted marker body 100. The above manufacturing process uses a resist material and an exposure process, enabling extremely high-precision manufacturing. That is, the dimensional variations in the outer shape of the marks 2 within one polygonal body 100 and the arrangement pitch of the marks 2 within each marker 1C can both be ±10 μm or less. More specifically, in this embodiment, the dimensional variations in the outer shape of the marks 2 within one polygonal body 100 and the arrangement pitch of the marks 2 within each marker 1C are both ±1 μm or less. Note that, in this embodiment, the outer shape of the marks 2 refers to the diameter of the marks 2, and the arrangement pitch of the marks 2 within each marker 1C refers to Px and Py shown in FIG. 10.

[0067] As described above, according to the third embodiment, the second layer 30C provided on the observation side is black, and the first layer 20C is white. This increases the hiding power of the base of the second layer 30C, allowing the thickness of the second layer 30C to be thinner than in the first embodiment. Therefore, when observing the mark 2 formed by the second layer 30C, the influence on measurement accuracy caused by observing the side end face of the second layer 30C can be minimized, enabling more accurate measurements. Furthermore, according to the third embodiment, by providing the planarizing layer 91, it is possible to prevent the occurrence of voids due to the stacking of the adhesive layer 60, and to prevent a decrease in measurement accuracy.

[0068] In the markers 1, 1B, and 1C of the first to third embodiments described above, the protective layers 70 and 70C are laminated via the adhesive layer 60. This configuration ensures that the markers 1, 1B, and 1C have extremely high reliability. For example, if the markers 1, 1B, and 1C are hit by an object during use, the base layer 10 may crack because it is a glass plate. However, because the protective layers 70 and 70C are laminated via the adhesive layer 60, the protective layers 70 and 70C function as shatterproof layers, preventing fragments of the base layer 10 from scattering. Furthermore, even if the base layer 10 cracks, the first layers 20 and 20C and the second layers 30 and 30C remain undamaged and can maintain their function as markers.

[0069] This is presumably because the bonding strength of the first layers 20, 20C and the second layers 30, 30C to the base layer 10 is weaker than the bonding strength to the adhesive layer 60, and the first layers 20, 20C and the second layers 30, 30C follow the adhesive layer 60, thereby avoiding damage. Therefore, it is desirable that the bonding strength of the first layers 20, 20C and the second layers 30, 30C to the base layer 10 is weaker than the bonding strength of the first layers 20, 20C and the second layers 30, 30C to the adhesive layer 60. It has been verified by a drop test using actual objects that the first layers 20, 20C and the second layers 30, 30C are not damaged even if the base layer 10 is cracked.

[0070] Furthermore, as described above, even if a crack occurs in the base material layer 10, the crack cannot be confirmed from the observation side. Therefore, a sensor for detecting damage may be provided on the back side of the base material layer 10. FIG. 11 is a diagram showing a configuration in which an electrode layer 95 is provided. The electrode layer 95 can be formed on substantially the entire back side of the base material layer 10 and can function as a sensor for detecting damage. The electrode layer 95 may be made of, for example, ITO, copper foil, or aluminum foil, but it is necessary that the electrode layer 95 be damaged together with the base material layer 10 when the base material layer 10 is damaged. If the electrode layer 95 is damaged and the electrical resistance value changes, this can be electrically monitored to detect damage to the base material layer 10. Furthermore, by forming the electrode layer 95 from a material such as a metal that has high light reflectivity, the electrode layer 95 can reflect external light and detection light, thereby improving the visibility of the mark 2 in a dark place. When the electrode layer 95 is provided, the protective layer 70C may be omitted.

[0071] (Fourth embodiment) FIG. 17 shows a fourth embodiment of a marker according to the present invention. Note that the following figures, including Figure 17, 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, but in general, these are used in order of thickness, that is, plate, sheet, film, and so on, and this specification follows suit. However, since there is no technical significance in this distinction, these terms can be used interchangeably as appropriate. In the present invention, "transparent" refers to a material that transmits at least light of the wavelength to be used. For example, even if a material does not transmit visible light, if it transmits infrared light, it will be treated as transparent when used in infrared applications. The specific numerical values ​​specified in the specification and claims should be treated as including a general margin of error. In other words, a difference of about ±10% is not substantially different, 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.

[0072] As shown in FIG. 17 , the marker 1 is configured as a substantially square plate when viewed from the normal direction of the surface on which the protective layer 70 (described later) is provided, and includes a mark 2 and moiré display areas 3 and 4. In this embodiment, the marker 1 is formed into a 60 mm × 60 mm square shape when viewed from the front side. The marker 1 detects the relative positional relationship between the shooting position and the marker 1 (hereinafter simply referred to as position detection) based on how the mark 2 is observed, and further enables more accurate position detection based on how the moiré displayed in the moiré display areas 3 and 4 is observed. Note that the surface of the marker 1 shown in FIG. 17 is the front side (front surface) that is observed, and the opposite side is the back side (rear surface). In FIG. 18 (described later), the side on which the protective layer 70 is provided is the front side (front surface) that is observed.

[0073] There are three marks 2 arranged at intervals, two near the two upper corners and one near the center of the lower left and right sides in Figure 17. Mark 2 is configured so that it can be observed as a mark with an independent shape. Note that an independent mark means that multiple marks are not connected and can be recognized individually. It is desirable that at least three marks 2 be arranged. This is because, for example, by calculating three center of gravity positions of the marks 2 from the observation results of the marks 2, it is possible to accurately detect the relative position and inclination between the observation position (camera, etc.) and the marker 1. Furthermore, if the number of marks 2 is more than three, for example, in cases where some marks 2 are obscured due to some obstacle, it is possible to detect their positions from the observation results of the remaining marks 2. Furthermore, by using multiple marks 2, it is possible to improve the accuracy of position detection. Furthermore, 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.

[0074] The moiré display areas 3 and 4 display a moiré M. FIG. 17 shows a state in which the moiré M is displayed in the center of both the moiré display areas 3 and 4. The position where this moiré M is displayed moves when the relative position (angle) between the marker 1 and the observation position changes. In this embodiment, the moiré display areas 3 and 4 each have a length of 30 mm in the longitudinal direction, and the position where the moiré M is displayed moves along this longitudinal direction. The moiré display areas 3 and 4 are arranged so that their longitudinal directions are orthogonal to each other. The display areas 3 and 4 have similar configurations except for the orientation in which they are arranged, so the following explanation will focus on the display area 3.

[0075] FIG. 18 is a cross-sectional view of the marker taken along the arrow AA in FIG. The marker 1 is configured in the shape of a thin plate and includes a base layer 10, a first layer 20, a second layer 30, a third layer 40, a reflective layer 50, an adhesive layer 60, and a protective layer 70. The order in which these layers are stacked from the back side is the reflective layer 50, the third layer 40, the base layer 10, the first layer 20, the second layer 30, the adhesive layer 60, and the protective layer 70.

[0076] 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 glass plate of the substrate layer used in this embodiment is Corning (registered trademark) EAGLE XG (registered trademark), and its linear expansion coefficient is 3.17 × 10 -6 / ℃. The linear expansion coefficient of the glass plate used as the substrate layer 10 is measured in accordance with JIS R3102. The linear expansion coefficient of ceramics is, for example, 28 x 10 -7 / °C, and dimensional change due to temperature change is very small, similar to glass. Therefore, ceramics may be used for the substrate layer. In order to suppress dimensional change due to temperature change, the substrate layer 10 has a linear expansion coefficient of 35×10 -6 It is desirable that the temperature is not higher than 100°C. An example of a ceramic that can be used as the substrate layer is silicon nitride (linear expansion coefficient is 2.8 × 10 -6 / °C) can be exemplified. A specific example is Denka SN Plate (manufactured by Denka Co., Ltd.). Other examples of ceramics that can be used as the substrate layer include an alumina substrate (96% alumina (manufactured by Nikko Co., Ltd.)), an alumina zirconia substrate (manufactured by MARURA Co., Ltd.), an aluminum nitride substrate (manufactured by MARURA Co., Ltd.), etc. In the case of ceramics, the linear expansion coefficient is measured in accordance with JIS R1618. The thickness of the base layer 10 is preferably 0.3 mm or more and 2.3 mm or less. If the thickness of the base layer 10 is less than 0.3 mm, it will break during cutting and cannot be further processed, and if it is thicker than 2.3 mm, it will be too heavy to transport. The thickness of the base layer 10 in this embodiment is 0.7 mm.

[0077] The first layer 20 is formed from a resist material colored black (first color). The resist material constituting the first layer 20 in this embodiment is a resist material that has lost its photosensitivity as a result of being developed into a photosensitive resist material used in a photolithography process. Examples of resist materials used for the first layer 20 (when black) include PMMA, ETA, HETA, HEMA, and mixtures with epoxy. Examples of materials that can be colored black include carbon, blackened titanium, and nickel oxide. In this embodiment, the first layer 20 is formed from a resist material, which allows the surface of the first layer 20 to be formed very smoothly, making it desirable as a base for forming the second layer 30 described below. Furthermore, since the first layer 20 is formed from a resist material, the first pattern 23 described below can be produced accurately and easily. The thickness of the first layer 20 (in the case of black) is preferably 1 μm or more and 5 μm or less. If the thickness of the first layer 20 is 1 μm or less, it cannot be formed uniformly, and if it is thicker than 5 μm, the curing reactivity of the resin with ultraviolet light is insufficient.

[0078] The first layer 20 constitutes the portion of the mark 2 that appears black. The first layer 20 also constitutes a first pattern 23 for displaying a moire pattern in the moire display area 3. The first pattern 23 is disposed in an area that will become the moire display area 3 on one surface (front surface) of the base layer 10. In the first pattern 23, first display lines 21 are arranged at equal intervals in a fixed arrangement direction in the longitudinal direction of the moiré display area 3. The areas between adjacent first display lines 21 where no first display line 21 is provided are first non-display areas 22, and the first display lines 21 and first non-display areas 22 are arranged alternately. The first pattern 23 is formed by photolithography.

[0079] The second layer 30 is formed of a resist material colored white (second color). The resist material constituting the second layer 30 in this embodiment is a resist material that has lost its photosensitivity as a result of being developed into a photosensitive resist material used in a photolithography process. Examples of resist materials used for the second layer 30 (when white) include PMMA, ETA, HETA, HEMA, and mixtures with epoxy. Examples of materials that can be colored white include titanium oxide, zirconia, and barium titanate. The second layer 30 has three openings 31 that open at positions that will become marks 2 and make the first layer 20 visible, and two openings 32 that open at positions that will become moiré display areas 3 and 4 and make the first layer 20 and the third layer 40 visible. These openings 31 and 32 are formed by photolithography.

[0080] The thickness of the second layer 30 is preferably 3 μm or more and 100 μm or less. If the thickness of the second layer 30 is thinner than 3 μm, the underlying first layer 20 will be visible, reducing contrast and the visibility (ease of detection by automatic recognition) of the mark 2. If the thickness of the second layer 30 is thicker than 100 μm, when the mark 2 is observed from an oblique direction, the area where the first layer 20 is hidden by the second layer 30 at the periphery of the opening 31 will increase, resulting in increased distortion of the shape of the observed mark 2.

[0081] The third layer 40 is formed of a resist material colored black (first color). The third layer 40 of this embodiment is made of the same material as the first layer 20, and the preferred film thickness is also the same as that of the first layer 20. Because the third layer 40 is formed of a resist material, the second pattern 43 described below can be produced accurately and easily.

[0082] The third layer 40 is provided with a second pattern 43 for displaying moiré in the moiré display area 3. The second pattern 43 is disposed opposite the first pattern 23 in an area that will become the moiré display area 3 on the rear surface of the base layer 10. In this embodiment, the first pattern 23 is provided on one surface of the base layer 10, and the second pattern 43 is provided on the other surface, but they may be provided on different base materials or the like and then bonded together to form the structure. In the second pattern 43, second display lines 41 are arranged at equal intervals in a fixed arrangement direction in the longitudinal direction of the moiré display area 3. The areas between adjacent second display lines 41 where no second display line 41 is provided are second non-display areas 42, and the second display lines 41 and second non-display areas 42 are arranged alternately. The second pattern 43 is formed by photolithography.

[0083] The reflective layer 50 is a layer that reflects light that reaches the marker 1 from the front side (observation side) through the opening 32 back to the front side. The reflective layer 50 can be made of, for example, PMMA, ETA, HETA, HEMA, or a mixture with epoxy, and is preferably white to enhance the contrast with the first indicator line 21 and the second indicator line 41. Examples of materials that can be colored white include titanium oxide, zirconia, and barium titanate.

[0084] Here, the reflective layer 50 may be laminated in close contact with the marker 1 so as to be integrated with it, as in this embodiment, or may be configured by disposing a separate reflective member or the like on the back surface of the marker 1. However, the configuration of this embodiment, in which the reflective layer 50 is laminated in close contact with the marker 1 so as to be integrated with it, is more desirable in that it can make the moire M significantly easier to see. The reason for this will be explained below.

[0085] The moiré M that we would like to observe is the moiré observed due to interference between the first display line 21 and the second display line 41. However, even if only the first display line 21 and only the second display line 41 are present, unwanted moiré (extraneous noise images) may occur depending on the conditions. FIG. 19 is an enlarged view of the vicinity of the second pattern 43 to explain the cause of unwanted moire. FIG. 19(a) shows a configuration in which the reflective layer 50 is laminated so as to fill the second non-display region 42. FIG. 19(b) shows a configuration in which the reflective layer 50 is laminated without filling the second non-display region 42. FIG. 19(c) shows a configuration in which the reflective layer 50 is laminated via a bonding layer 51 such as an adhesive layer. When the second non-display region 42 is not filled with the reflective layer 50, as in the configurations of FIGS. 19(b) and 19(c), light L1 incident from the observation side is reflected by the ends of the second display lines 41, etc., and returns to the observation side, generating unwanted light L3 and L4. It is believed that unwanted moire occurs because such unwanted light L3 and L4 also occur periodically. On the other hand, in a configuration in which the reflective layer 50 is stacked to fill the second non-display area 42 as shown in Figure 19(a), light cannot reach the ends of the second display line 41, etc., so normal reflected light L2 returns to the observation side, thereby suppressing the occurrence of unnecessary moire and making it possible to observe clear moire. In this way, when unwanted moire patterns of second display lines 41 are generated by light that is scattered at the side portions of second display lines 41, i.e., at the end faces of second display lines 41 on the second non-display area 42 side and returns to the viewer side, it is thought that this interferes with the moire patterns M that are intended to be seen, making it difficult to observe the moire patterns M. Therefore, by providing reflective layer 50 so as to fill second non-display area 42, the above phenomenon can be avoided and moire patterns M can be observed more clearly. For the above reasons, it is sufficient that the reflective layer 50 is provided in at least the second non-display area 42, but it is desirable that it be provided so as to cover the back side of the second display lines 41, as shown in Fig. 18. The reason for this is that the reflection of light from the edge portions on the back side of the second display lines 41 is suppressed, and the main component of the periodic reflected light can be eliminated.

[0086] The adhesive layer 60 is a layer of adhesive for attaching the protective layer 70 onto the second layer 30. The adhesive layer 60 is made of a transparent adhesive so that the first layer 20 and the second layer 30 can be observed. The adhesive layer 60 can be made of, for example, PMMA, urethane, silicone, etc. The thickness of the adhesive layer 60 is preferably 0.5 μm or more and 50 μm or less. If the thickness of the adhesive layer 60 is less than 0.5 μm, it is difficult to achieve uniform processing and the unevenness of the base material cannot be absorbed. Also, if the thickness of the adhesive layer 60 is thicker than 50 μm, it takes time to remove the solvent during thick coating processing and the cost is high.

[0087] The protective layer 70 is a layer that protects the first layer 20 and the second layer 30, and is attached onto the second layer 30 via an adhesive layer 60. The protective layer 70 has a resin substrate layer 71 and a surface layer 72.

[0088] The resin base material layer 71 has an adhesive layer 60 laminated on one surface thereof and a surface layer 72 laminated on the other surface thereof. The resin base material layer 71 is made of a transparent resin so that the first layer 20 and the second layer 30 can be observed. In this embodiment, it is assumed that the marker 1 will be used under visible light, and the adhesive layer 60 and the resin base material layer 71 are configured to be transparent to white light. Specifically, the adhesive layer 60 and the resin base material layer 71 each preferably have a total light transmittance of 50% or more in the light wavelength range of 400 nm to 700 nm. More preferably, when the adhesive layer 60 and the resin base material layer 71 are measured together, the total light transmittance in the light wavelength range of 400 nm to 700 nm is preferably 50% or more. The thickness of the resin substrate layer 71 is preferably 7 μm or more and 250 μm or less. This is because lamination processing is difficult if the thickness of the resin substrate layer 71 is less than 7 μm. On the other hand, if the thickness of the resin substrate layer 71 is greater than 250 μm, the layer becomes too bulky and heavy, and costs become high. The refractive index of the resin substrate layer 71 is preferably 1.45 or more and 1.55 or less.

[0089] The surface layer 72 is a layer that combines anti-reflection and hard coating functions. It is desirable that the surface layer 72 have a reflectance of 1.5% or less for light with a wavelength of 535 nm in order to prevent a decrease in the visibility of the mark 2 and the moire display areas 3 and 4 due to reflection on the surface of the marker 1. Furthermore, as a hard coating function, the surface layer 72 desirably has a pencil hardness of 1H or more. The surface layer 72 can be made of, for example, sol-gel, siloxane, polysilazane, or the like. Specific methods for anti-reflection include anti-reflection (AR) and anti-glare (AG), but the AR method is preferable for recognizing the mark 2 under conditions where strong light such as sunlight does not specularly reflect. The AG method is preferable for recognizing the mark 2 under conditions where strong light such as sunlight may specularly reflect. The AR method can be produced by known methods such as multilayer thin film interference and moth-eye methods, and the AG method can be produced by known methods such as making the surface of the film uneven, incorporating light-diffusing particles into the film, or coating the surface of the film.

[0090] As explained above, the first non-display area 22 is filled with the adhesive layer 60, but because the adhesive layer 60 and the protective layer 70 are transparent and the base layer 10 is also made of glass and is transparent, the second pattern 43 of the third layer 40 can be seen through the first non-display area 22. Therefore, when the marker 1 is observed from the front side, the first pattern 23 and the second pattern 43 are seen overlapping each other, and the moiré pattern M can be observed.

[0091] Furthermore, it is desirable that the total light transmittance be 85% or more as a combined characteristic of the adhesive layer 60 and the protective layer 70. If the total light transmittance is less than 85%, a sufficient amount of light cannot be ensured. Furthermore, as a combined characteristic of the adhesive layer 60 and the light diffusion layer 70, it is desirable that the haze value be 30% or more, more preferably 40% or more, and even more preferably 70% or more. This is because the effect of the present invention begins to decrease when the haze value is lower than 70%, decreases further when it is 40% or less, and decreases significantly when it is 30% or less. On the other hand, it is desirable that the haze value be 95% or less. This is because if the haze value is higher than 95%, the image of the mark observed will become blurred.

[0092] Conventionally, when moiré patterns are created by overlapping multiple patterns, as described in Patent Document 1 (U.S. Patent No. 8,625,107), the pattern positioned on the observation side blocks light, causing the entire image to appear dark. Even when moiré patterns appear in a dark environment, the moiré patterns are often unclear, making it difficult to identify their location by photographing them with a camera. Therefore, in this embodiment, the first pattern 23 and the second pattern 43 are improved to enable the moiré patterns to be observed more clearly.

[0093] Fig. 20 is a diagram illustrating the details of the first pattern 23 and the second pattern 43. Note that Fig. 20 shows a cross section similar to Fig. 18, but only shows three layers: the base layer 10, the first layer 20, and the third layer 40. In this embodiment, the width of the first non-display region 22 is different from the width of the second non-display region 42. Specifically, in this embodiment, the width of the first non-display region 22 is 0.64 mm, and the width of the second non-display region 42 is 0.1 mm. The first non-display region 22 is disposed on the observation side (front side), and the width of the first non-display region 22 is wider than the width of the second non-display region 42. Therefore, more light reaches the second pattern 43 through the first pattern 23, and further, most of the light that is reflected and returned to the observation side can reach the observation position through the first pattern 23. Therefore, the moire M can be observed more brightly.

[0094] Furthermore, the width of the first display lines 21 and the width of the second display lines 41 are different. This makes it possible to observe the moire M more clearly than when the two lines have the same width. Specifically, the width of the first display lines 21 is set to 0.1 mm, and the width of the second display lines is set to 0.4 mm. By making the width of the first display lines 21 thinner than the width of the second display lines in this way, more light passes through the first pattern 23, and the moire M can be observed more brightly.

[0095] The first pitch, which is the pitch at which the first display lines 21 are arranged, is set to 0.74 mm, and the second pitch, which is the pitch at which the second display lines 41 are arranged, is set to 0.5 mm, so that the two are different. This makes it possible to observe the moire M more clearly. Furthermore, because the first pitch is wider than the second pitch, the width of the first non-display area 22 is consequently wider than the width of the second non-display area 42, and the moire M can be observed more brightly.

[0096] Next, an example of how to use the marker 1 of this embodiment will be described. Fig. 21 is a diagram showing the marker 1 as viewed from an oblique direction. Fig. 21 illustrates an example in which the marker 1 is observed from the oblique direction indicated by arrow B in Fig. 18, but without tilting in the up and down directions in Fig. 17. When the marker 1 is observed from an oblique direction tilted from its normal direction, for example, as shown in Fig. 21, the moire M in the moire display area 3 is observed to move in the longitudinal direction of the moire display area 3. When the marker 1 is observed from an oblique direction tilted from its normal direction to the longitudinal direction of the moire display area 4, the moire M in the moire display area 4 is observed to move in the longitudinal direction of the moire display area 4. Therefore, by observing both the moire M in the moire display area 3 and the moire M in the moire display area 4, the relative position (angle of tilt) between the marker 1 and the observation position can be accurately detected. In other words, the marker 1 can be used in combination with an imaging unit and a calculation unit to form part of an angle sensor.

[0097] Here, when the observation position is moved to a position significantly deviated from the normal direction of the marker 1, another moiré pattern is observed, and moiré patterns are observed one after another. Therefore, if the observation position is located at a position significantly deviated from the normal direction of the marker 1, it may not be possible to detect the position correctly. However, the marker 1 of this embodiment includes a mark 2. Position detection using the mark 2 allows position detection even when the observation position is significantly deviated from the normal direction of the marker 1. On the other hand, position detection using the moiré display areas 3 and 4 allows position detection with even higher accuracy than position detection using the mark 2. Therefore, by using the position detection using the mark 2 in combination with the position detection using the moiré display areas 3 and 4, the range of application can be expanded compared to when only the moiré display areas 3 and 4 are used. In other words, even when the observation position is significantly deviated from the normal direction of the marker 1, position detection can be performed using the mark 2, and the observation position can be automatically moved according to the detection result. Finally, position detection using the moiré display areas 3 and 4 can be performed at a stage where final, highly accurate position control is required.

[0098] As described above, according to the marker 1 of this embodiment, the width of the first non-display area 22 is wider than the width of the second non-display area 42, and therefore more light can be taken into the moiré display areas 3 and 4 and more light can be returned to the observation side, allowing the moiré M to be displayed brighter. Therefore, even if the moiré M displayed in the moiré display areas 3 and 4 is photographed with a camera or the like, its position can be obtained more accurately, enabling highly accurate position detection.

[0099] (Fifth embodiment) FIG. 22 shows a fifth embodiment of a marker according to the present invention. Note that the figures shown below, including Figure 22, 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, but in general, these are used in order of thickness, that is, plate, sheet, film, and so on, and this specification follows suit. However, since there is no technical significance in this distinction, these terms can be used interchangeably as appropriate. In the present invention, "transparent" refers to a material that transmits at least light of the wavelength to be used. For example, even if a material does not transmit visible light, if it transmits infrared light, it will be treated as transparent when used in infrared applications. The specific numerical values ​​specified in the specification and claims should be treated as including a general margin of error. In other words, a difference of about ±10% is not substantially different, 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.

[0100] As shown in FIG. 22, the marker 1 has a substantially square plate shape when viewed from the normal direction of the surface on which the light diffusion layer 80 (described later) is provided, and includes a mark 2 and moiré display areas 3 and 4. In this embodiment, the marker 1 is formed into a 60 mm × 60 mm square shape when viewed from the front side. The marker 1 detects the relative positional relationship between the shooting position and the marker 1 (hereinafter simply referred to as position detection) based on how the mark 2 is observed, and further enables more accurate position detection based on how the moiré displayed in the moiré display areas 3 and 4 is observed. Note that the surface of the marker 1 shown in FIG. 22 is the front side (front surface) from which the image is captured, and the opposite side is the back side (rear surface). In FIG. 23 (described later), the side on which the light diffusion layer 80 is provided is the front side (front surface) from which the image is captured.

[0101] There are three marks 2 arranged at intervals, two near the two upper corners and one near the center of the lower left and right sides in Figure 22. Mark 2 is configured so that it can be observed as an independent mark. Note that an independent mark means that multiple marks are not connected and can be recognized individually. It is desirable that at least three marks 2 be arranged. This is because, for example, by calculating three center of gravity positions of the marks 2 from the observation results of the marks 2, it is possible to accurately detect the relative position and inclination between the observation position (camera, etc.) and the marker 1. Furthermore, if the number of marks 2 is more than three, for example, in cases where some marks 2 are obscured due to some obstacle, it is possible to detect their positions from the observation results of the remaining marks 2. Furthermore, by using multiple marks 2, it is possible to improve the accuracy of position detection. Furthermore, 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.

[0102] The moiré display areas 3 and 4 display a moiré M. FIG. 22 shows a state in which the moiré M is displayed in the center of both the moiré display areas 3 and 4. The position where this moiré M is displayed moves when the relative position (angle) between the marker 1 and the observation position changes. In this embodiment, the moiré display areas 3 and 4 each have a length of 30 mm in the longitudinal direction, and the position where the moiré M is displayed moves along this longitudinal direction. The moiré display areas 3 and 4 are arranged so that their longitudinal directions are orthogonal to each other. The moiré display areas 3 and 4 have the same configuration except for the arrangement direction, so the following explanation will focus on the moiré display area 3.

[0103] FIG. 23 is a cross-sectional view of the marker taken along the arrow AA in FIG. The marker 1 is configured in the shape of a thin plate and includes a base layer 10, a first layer 20, a second layer 30, a third layer 40, a reflective layer 50, an adhesive layer 60, and a light diffusion layer 80. The order in which these layers are stacked from the back side is the reflective layer 50, the third layer 40, the base layer 10, the first layer 20, the second layer 30, the adhesive layer 60, and the light diffusion layer 80.

[0104] 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 glass plate of the substrate layer used in this embodiment is Corning (registered trademark) EAGLE XG (registered trademark), and its linear expansion coefficient is 3.17 × 10 -6 / ℃. The linear expansion coefficient of the glass plate used as the substrate layer 10 is measured in accordance with JIS R3102. The linear expansion coefficient of ceramics is, for example, 28 x 10 -7 / °C, and dimensional change due to temperature change is very small, similar to glass. Therefore, ceramics may be used for the substrate layer. In order to suppress dimensional change due to temperature change, the substrate layer 10 has a linear expansion coefficient of 35×10 -6 It is desirable that the temperature is not higher than 100°C. An example of a ceramic that can be used as the substrate layer is silicon nitride (linear expansion coefficient is 2.8 × 10 -6 / °C) can be exemplified. A specific example is Denka SN Plate (manufactured by Denka Co., Ltd.). Other examples of ceramics that can be used as the substrate layer include an alumina substrate (96% alumina (manufactured by Nikko Co., Ltd.)), an alumina zirconia substrate (manufactured by MARURA Co., Ltd.), an aluminum nitride substrate (manufactured by MARURA Co., Ltd.), etc. In the case of ceramics, the linear expansion coefficient is measured in accordance with JIS R1618. The thickness of the base layer 10 is preferably 0.3 mm or more and 2.3 mm or less. If the thickness of the base layer 10 is less than 0.3 mm, it will break during cutting and cannot be further processed, and if it is thicker than 2.3 mm, it will be too heavy to transport. The thickness of the base layer 10 in this embodiment is 0.7 mm.

[0105] The first layer 20 is formed of a resist material colored black (first color). The resist material constituting the first layer 20 in this embodiment is a resist material that has lost its photosensitivity as a result of being developed into a photosensitive resist material used in a photolithography process. Examples of resist materials used for the first layer 20 (when black) include PMMA (Poly Methyl Methacrylate), ETA (Eicosatetraenoic Acid), HETA (Hydroxyeicosatetraenoic Acid), HEMA (2-Hydroxyethyl methacrylate), and mixtures with epoxy. Examples of materials that can be colored black include carbon, blackened titanium, and nickel oxide. In this embodiment, the first layer 20 is formed from a resist material, which allows the surface of the first layer 20 to be formed very smoothly, making it desirable as a base for forming the second layer 30 described below. Furthermore, since the first layer 20 is formed from a resist material, the first pattern 23 described below can be produced accurately and easily. The thickness of the first layer 20 (in the case of black) is preferably 1 μm or more and 5 μm or less. If the thickness of the first layer 20 is 1 μm or less, it cannot be formed uniformly, and if it is thicker than 5 μm, the curing reactivity of the resin with ultraviolet light is insufficient.

[0106] The first layer 20 constitutes the portion of the mark 2 that appears black. The first layer 20 also constitutes a first pattern 23 for displaying a moire pattern in the moire display area 3. The first pattern 23 is disposed in an area that will become the moire display area 3 on one surface (front surface) of the base layer 10. In the first pattern 23, first display lines 21 are arranged at equal intervals in a fixed arrangement direction in the longitudinal direction of the moiré display area 3. The areas between adjacent first display lines 21 where no first display line 21 is provided are first non-display areas 22, and the first display lines 21 and first non-display areas 22 are arranged alternately. The first pattern 23 is formed by photolithography.

[0107] The second layer 30 is formed of a resist material colored white (second color). The resist material constituting the second layer 30 in this embodiment is a resist material that has lost its photosensitivity as a result of being developed into a photosensitive resist material used in a photolithography process. Examples of resist materials used for the second layer 30 (when white) include PMMA, ETA, HETA, HEMA, and mixtures with epoxy. Examples of materials that can be colored white include titanium oxide, zirconia, and barium titanate. The second layer 30 has three openings 31 that open at positions that will become marks 2 and make the first layer 20 visible, and two openings 32 that open at positions that will become moiré display areas 3 and 4 and make the first layer 20 and the third layer 40 visible. These openings 31 and 32 are formed by photolithography.

[0108] The thickness of the second layer 30 is preferably 3 μm or more and 100 μm or less. If the thickness of the second layer 30 is thinner than 3 μm, the underlying first layer 20 will be visible, reducing contrast and the visibility (ease of detection by automatic recognition) of the mark 2. If the thickness of the second layer 30 is thicker than 100 μm, when the mark 2 is observed from an oblique direction, the area where the first layer 20 is hidden by the second layer 30 at the periphery of the opening 31 will increase, resulting in increased distortion of the shape of the observed mark 2.

[0109] The third layer 40 is formed of a resist material colored black (first color). The third layer 40 of this embodiment is made of the same material as the first layer 20, and the preferred film thickness is also the same as that of the first layer 20. Because the third layer 40 is formed of a resist material, the second pattern 43 described below can be produced accurately and easily.

[0110] The third layer 40 is provided with a second pattern 43 for displaying moiré in the moiré display area 3. The second pattern 43 is disposed opposite the first pattern 23 in an area that will become the moiré display area 3 on the rear surface of the base layer 10. In this embodiment, the first pattern 23 is provided on one surface of the base layer 10, and the second pattern 43 is provided on the other surface, but they may be provided on different base materials or the like and then bonded together to form the structure. In the second pattern 43, second display lines 41 are arranged at equal intervals in a fixed arrangement direction in the longitudinal direction of the moiré display area 3. The areas between adjacent second display lines 41 where no second display line 41 is provided are second non-display areas 42, and the second display lines 41 and second non-display areas 42 are arranged alternately. The second pattern 43 is formed by photolithography.

[0111] The reflective layer 50 is a layer that reflects light that reaches the marker 1 from the front side (observation side) through the opening 32 back to the front side. The reflective layer 50 can be made of, for example, PMMA, ETA, HETA, HEMA, or a mixture with epoxy, and is preferably white to enhance the contrast with the first indicator line 21 and the second indicator line 41. Examples of materials that can be colored white include titanium oxide, zirconia, and barium titanate.

[0112] Here, the reflective layer 50 may be laminated in close contact with the marker 1 so as to be integrated with it, as in this embodiment, or may be configured by disposing a separate reflective member or the like on the back surface of the marker 1. However, the configuration of this embodiment, in which the reflective layer 50 is laminated in close contact with the marker 1 so as to be integrated with it, is more desirable in that it can make the moire M significantly easier to see. The reason for this will be explained below.

[0113] The moire M that is actually desired to be observed is a moire observed due to interference between the first display lines 21 and the second display lines 41. However, even when only the first display lines 21 or only the second display lines 41 are present, unwanted moire (extraneous noise images) may occur depending on the conditions. When unwanted moire of the second display lines 41 occurs due to light that is scattered at the side portions of the second display lines 41, i.e., at the end faces of the second display lines 41 that are on the second non-display region 42 side and returns to the viewer, it is thought that this interferes with the moire M that is actually desired to be seen, making it difficult to observe the moire M. Therefore, by providing the reflective layer 50 so that it fills the second non-display region 42, the above phenomenon can be avoided and the moire M can be observed more clearly. For the above reasons, it is sufficient that the reflective layer 50 is provided in at least the second non-display area 42, but it is desirable that it be provided so as to cover the back side of the second display lines 41, as shown in Fig. 23. The reason for this is that the reflection of light from the edge portions on the back side of the second display lines 41 is suppressed, and the main component of the periodic reflected light can be eliminated.

[0114] The adhesive layer 60 is a layer of adhesive for attaching the light diffusion layer 80 onto the second layer 30. The adhesive layer 60 can be made of, for example, PMMA, urethane, silicone, or the like. The thickness of the adhesive layer 60 is preferably 0.5 μm or more and 50 μm or less. If the thickness of the adhesive layer 60 is less than 0.5 μm, it is difficult to achieve uniform processing and the unevenness of the base material cannot be absorbed. Also, if the thickness of the adhesive layer 60 is thicker than 50 μm, it takes time to remove the solvent during thick coating processing and the cost is high. The adhesive layer 60 is provided only in the same area as the area where the light diffusion layer 80 is provided.

[0115] The light diffusion layer 80 covers the mark 2 and the moire display areas 3 and 4 via the adhesive layer 60, and is provided in an island shape over an area slightly larger than these. Specifically, the light diffusion layer 80 is provided in an island shape over an area 2 to 3 mm larger on one side (radius) than the mark 2. Similarly, the light diffusion layer 80 is provided in an island shape over an area 2 to 3 mm larger on one side (expansion width on one side) than the moire display areas 3 and 4. By providing the light diffusion layer 80 in an island shape and not providing the light diffusion layer 80 in other parts, it is possible to easily provide a light diffusion layer later as needed. Furthermore, when strong light such as sunlight is incident on only one island-shaped light diffusion layer 80, if the light diffusion layer 80 (including the resin base material layer 81) is connected, the resin base material layer 81 acts as a light guide plate and propagates to other island-shaped light diffusion layers 80, preventing the light from affecting the other islands. The light diffusion layer 80 includes a resin substrate layer 81 and a surface layer 82 .

[0116] The resin base material layer 81 has an adhesive layer 60 laminated on one surface thereof and a surface layer 82 laminated on the other surface thereof. The resin base material layer 81 is made of a transparent resin so that the first layer 20 and the second layer 30 can be observed. In this embodiment, it is assumed that the marker 1 will be used under visible light, and the adhesive layer 60 and the resin base material layer 81 are configured to be transparent to white light. Specifically, the adhesive layer 60 and the resin base material layer 81 each preferably have a total light transmittance of 50% or more in the light wavelength range of 400 nm to 700 nm. More preferably, when the adhesive layer 60 and the resin base material layer 81 are measured together, the total light transmittance in the light wavelength range of 400 nm to 700 nm is preferably 50% or more. The thickness of the resin substrate layer 81 is preferably 7 μm or more and 250 μm or less. This is because lamination processing is difficult if the thickness of the resin substrate layer 81 is less than 7 μm. On the other hand, if the thickness of the resin substrate layer 81 is greater than 250 μm, the bulk and weight become too large, and the cost becomes high. The refractive index of the resin base material layer 81 is preferably 1.45 or more and 1.55 or less.

[0117] The surface layer 82 is a layer that exhibits a light diffusing effect. The surface of the surface layer 82 in this embodiment has a fine uneven shape on its surface, forming a so-called matte surface (rough surface). The surface layer 82 diffuses surface-reflected light by using this fine uneven shape. Here, various antireflection layers used in antiglare films can be applied to the surface layer 82 having such a fine uneven shape. For example, the surface layer 82 may be made by embossing, may be made by mixing translucent fine particles to make the surface rough, may be made by dissolving the surface with a chemical to make the surface rough (a so-called chemical matte surface), or may be made by a molding process using a moldable resin layer.

[0118] Furthermore, the surface layer 82 has a hard coating function. The hard coating function of the surface layer 82 desirably has a pencil hardness of 1H or more. By providing the surface layer 82 with a hard coating function, the light diffusion layer 80 can also function as a protective layer. Furthermore, it is desirable that the surface layer 82 has a regular reflectance of 1.5% or less for light with a wavelength of 535 nm in order to prevent the visibility of the mark 2 and the moire display areas 3 and 4 from being reduced due to reflection on the surface of the marker 1.

[0119] Furthermore, it is desirable that the total light transmittance be 85% or more as a combined characteristic of the adhesive layer 60 and the light diffusion layer 80. If the total light transmittance is less than 85%, a sufficient amount of light cannot be ensured. Furthermore, as a combined characteristic of the adhesive layer 60 and the light diffusion layer 80, it is desirable that the haze value be 30% or more, more preferably 40% or more, and even more preferably 70% or more. This is because the effect of the present invention begins to decrease when the haze value is lower than 70%, decreases further when the haze value is 40% or less, and decreases significantly when the haze value is 30% or less. On the other hand, it is desirable that the haze value be 95% or less. This is because if the haze value is higher than 95%, the image of the mark observed will become blurred.

[0120] FIG. 24 is a graph showing the effect of the light diffusion layer 80. In order to confirm the effect of providing the light diffusion layer 80, two types of markers were actually created, one with the light diffusion layer 80 and one without. Then, the two types of markers were illuminated so that the reflected light was strong at the position of mark 2 and returned to the camera, and they were photographed. The change in light intensity depending on the position near the part of mark 2 where black and white are inverted was quantified and shown in Figure 24. 24, when there is no light diffusion layer 80, the reflection of the illumination light appears as a waveform, and no waveform corresponding to the shape of the mark 2 is observed. Note that when there is no light diffusion layer 80, the light intensity is too strong, exceeding the measurement limit (2.50E+02). In contrast, when the light diffusion layer 80 was provided, data was obtained that allowed the light intensity of the white portion and the light intensity of the black portion to be appropriately separated and recognized in accordance with the position of the mark 2. When the light diffusion layer 80 was measured using a haze meter "HM-150" manufactured by Murakami Color Research Institute, which complies with JIS K7136, the total light transmittance was 90.3% and the haze value was 75.1%. As can be seen from Figure 24, if the light diffusion layer is arranged so as to straddle the mark and its surrounding area, the shape (outline) of the mark can be clearly captured by the camera. Furthermore, if a light diffusion layer is placed only on the mark with the same shape and size as the mark, the resin substrate layer portion of the light diffusion layer will act as a light guide plate, causing light to be emitted from the edge of the resin substrate layer, resulting in the problem of the mark shape (outline) becoming unclear.

[0121] Next, an example of how to use the marker 1 of this embodiment will be described. Fig. 25 is a diagram showing the marker 1 as viewed from an oblique direction. Fig. 25 illustrates an example in which the marker 1 is observed from the oblique direction indicated by arrow B in Fig. 23, but without tilting in the up and down directions in Fig. 22. When the marker 1 is observed from an oblique direction tilted from its normal direction, for example, as shown in Fig. 25, the moire M in the moire display area 3 is observed to move in the longitudinal direction of the moire display area 3. When the marker 1 is observed from an oblique direction tilted from its normal direction to the longitudinal direction of the moire display area 4, the moire M in the moire display area 4 is observed to move in the longitudinal direction of the moire display area 4. Therefore, by observing both the moire M in the moire display area 3 and the moire M in the moire display area 4, the relative position (angle of tilt) between the marker 1 and the observation position can be accurately detected. In other words, the marker 1 can be used in combination with an imaging unit and a calculation unit to form part of an angle sensor.

[0122] Here, when the observation position is moved to a position significantly deviated from the normal direction of the marker 1, another moiré pattern is observed, and moiré patterns are observed one after another. Therefore, if the observation position is located at a position significantly deviated from the normal direction of the marker 1, it may not be possible to detect the position correctly. However, the marker 1 of this embodiment includes a mark 2. Position detection using the mark 2 allows position detection even when the observation position is significantly deviated from the normal direction of the marker 1. On the other hand, position detection using the moiré display areas 3 and 4 allows position detection with even higher accuracy than position detection using the mark 2. Therefore, by using the position detection using the mark 2 in combination with the position detection using the moiré display areas 3 and 4, the range of application can be expanded compared to when only the moiré display areas 3 and 4 are used. In other words, even when the observation position is significantly deviated from the normal direction of the marker 1, position detection can be performed using the mark 2, and the observation position can be automatically moved according to the detection result. Finally, position detection using the moiré display areas 3 and 4 can be performed at a stage where final, highly accurate position control is required.

[0123] As described above, various relative positions between the observation position and the marker 1 are expected. Therefore, there may be a positional relationship in which illumination light, sunlight, etc. are specularly reflected toward the observation position. Even in such a case, the marker 1 of this embodiment has a light diffusion layer 80, which can appropriately diffuse reflected light and increase the number of situations in which the marker mark 2 and the moire display areas 3 and 4 can be observed.

[0124] As described above, the marker 1 of this embodiment can improve situations in which it becomes difficult to recognize the indicators and other elements indicated by the marker 1 due to illumination light or sunlight, and can provide a marker that is easy to recognize even in environments where sunlight, illumination light, etc. hits the marker.

[0125] (Sixth embodiment) FIG. 27 shows a sixth embodiment of a marker according to the present invention. The marker 1 of the sixth embodiment includes a mark 2, moiré display areas 3 and 4, and an identification mark 5. The marker 1 of the sixth embodiment is similar to the other embodiments described above, except that the arrangement of the mark 2 and the moiré display areas 3 and 4 is different, and an identification mark 5 is provided. Therefore, parts that perform the same functions as those of the above-described embodiments are given the same reference numerals, and redundant explanations will be omitted as appropriate. The layer structure of the marker 1 of the sixth embodiment is similar to that of the marker 1 of the first embodiment, but may also be configured similarly to that of the marker 1C of the third embodiment.

[0126] In this embodiment, marks 2 are provided near each of the four corners. Moiré display areas 3 are provided near each of the top and bottom edges in FIG. 27. Moiré display areas 4 are provided near each of the left and right edges in FIG. 27. An identification mark 5 is provided in the center of the marker 1. The identification mark 5 is a pattern graphic (graphic for identification) that displays unique information by its pattern, with a specific meaning associated with the pattern of the mark. For example, the identification mark 5 is associated with a unique number, alphabet, or the like 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 as in this embodiment, which has a reduced number of patterns and a larger pattern, it can be easily detected by a camera.

[0127] FIG. 28 is a diagram showing a pallet P to which a marker 1 according to the sixth embodiment is attached. The marker 1 of this embodiment can be attached to, for example, a pallet P used in logistics and used to identify the pallet P as a detection target. Therefore, for example, the relative positional relationship between the forklift and the pallet can be accurately determined from the results of photography by a camera on an autonomous forklift, and the operation of the forklift can be controlled based on this relative positional relationship, and further, the pallet P can be individually identified. The marker 1 may be attached to the detection object using, for example, a pressure sensitive adhesive or glue, or the marker 1 may be attached detachably to a pallet P provided with a mounting shape for mounting the marker 1 thereon.

[0128] The marker 1 of this embodiment is equipped with an identification mark 5, and therefore can be used not only for position detection as in the other embodiments described above, but also to identify the object to which the marker 1 is attached. Note that Figures 27 and 28 show an example of marker 1 with moiré display areas 3 and 4, but the purpose of the moiré display areas is to measure the inclination of the marker with high precision, so if the measurement accuracy using mark 2 alone is sufficient to achieve the desired accuracy, the moiré display areas can be omitted.

[0129] Furthermore, when attaching the marker 1 to a pallet P used in logistics, it is preferable that the protective layers 70, 70C are laminated via the adhesive layer 60. Even if the marker 1 is hit by the claws of a forklift, for example, the protective layers 70, 70C function as anti-scattering layers, preventing fragments of the base layer 10 from scattering. Furthermore, even if the base layer 10 is cracked, the first layers 20, 20C and the second layers 30, 30C will not be damaged and will be able to maintain their function as markers.

[0130] FIG. 29 is a diagram showing a measurement system 500 including the marker 1 of the sixth embodiment. The measurement system 500 is not limited to the marker 1 of the sixth embodiment, and can also use the markers 1, 1B, 1C, etc. described in the first to sixth embodiments. The measurement system 500 includes a pallet P to which the marker 1 of the sixth embodiment described above is attached, and a forklift 200. The forklift 200 includes a camera (photographing unit) 201, a calculation unit 202, and a control unit 203.

[0131] The camera (photographing unit) 201 is provided so as to be able to photograph the area in front of the forklift 200, and is provided to photograph the marker 1. The calculation unit 202 calculates the relative positional relationship between the camera 201 and the marker 1 using an image of the mark 2 included in the image of the marker 1 captured by the camera 201. The calculation method (measurement method) used by the calculation unit 202 to calculate the dimensions or orientation of mark 2 using a captured image of mark 2 is the method described in Hideyuki Tanaka, "Fundamentals and Latest Trends in AR Marker Technology," Journal of the Institute of Electrical, Information and Communication Engineers, Vol. 97, No. 8, 2014, pp. 734-740. This technology is also publicly available at the following URL: "Detection of ArUco Markers" [Retrieved June 6, 2022], Internet<URL:https: / / docs.opencv.org / 4.x / d5 / dae / tutorial_aruco_detection.html> This web page describes the Pose Estimation section, and if you consider the centers of the four marks 2 as the coordinate vectors of the four corners of the ArUco Marker, you can easily calculate it using functions from OpenCV (Open Source Computer Vision Library). In the present embodiment for controlling the forklift 200, the calculation unit 202 calculates (measures) the relative positional relationship between the camera 201 and the marker 1, but other calculations (measurements) are also possible. For example, the calculation unit 202 can perform the following calculations.

[0132] (Calculation example 1) First, the calculation unit 202 can calculate the relative positional relationship between the camera 201 and the mark 2. The relative positional relationship between the camera 201 and the mark 2 includes not only the dimension (distance) from the camera 201 to the mark 2, but also the direction in which the front of the mark 2 (marker 1) faces, that is, the attitude of the mark (the attitude of the marker 1 including the mark 2). Here, the attitude of the mark 2 can be expressed, for example, by roll, yaw, and pitch.

[0133] (Calculation example 2) The calculation unit 202 can also calculate the dimensions of an object or the like near the mark 2. For example, it can measure the height of a person standing near the marker 1 that displays the mark 2. People can be recognized automatically. In addition to people, it can also be the height of a tree, the size of an animal, the size of a window, or the like.

[0134] (Calculation example 3) Furthermore, the calculation unit 202 can calculate the dimension (distance) between positions designated near the mark 2. The positions designated near the mark 2 are positions designated by the user within the range photographed together with the mark 2 on the image photographed by the camera 201.

[0135] (Calculation example 4) Furthermore, the calculation unit 202 can calculate the dimensions (distances) between multiple markers 1 (marks 2). When multiple markers 1 are placed, the dimensions (distances) between the multiple marks 2 can be calculated by capturing images of the multiple marks 2 within a single screen using the camera 201. As described above, the calculation unit 202 can calculate the relative positional relationship between the camera 201 and the markers 1 (marks 2). Therefore, even if multiple markers 1 are captured separately without moving the position of the camera 201, the dimensions (distances) between the multiple markers 1 (marks 2) can be calculated. At this time, each marker 1 can be recognized separately based on the unique information represented by the identification mark 5, so that the calculation can be performed correctly.

[0136] The control unit 203 performs control based on the calculation results of the calculation unit 202. In this embodiment, the control performed by the control unit 203 is overall control of the operation of the forklift 200, including the up and down movement of the forks 200a. The control unit 203 has in advance information such as the shape and size of the pallet P and the position on the pallet P where the marker 1 is attached. Therefore, the control unit 203 can grasp the relative positional relationship between the pallet P and the forklift 200 from the relative positional relationship between the marker 1 and the camera 201 calculated by the calculation unit 202. By accurately grasping the ever-changing relative positional relationship between the pallet P and the forklift 200, the control unit 203 can accurately move the forklift 200 to the target pallet P and appropriately operate the forks 200a. Here, the identification mark 5 is provided on the marker 1, so that each individual pallet P can be identified.

[0137] The calculation unit 202 and the control unit 203 of this embodiment are configured by installing a computer program in a computer. More specifically, the calculation unit 202 and the control unit 203 of this embodiment are configured by installing an application program for the measurement system of the present invention in a computer used to control the forklift 200. The computer used to control the forklift 200 may be a general-purpose smartphone or tablet terminal, a laptop computer, or a dedicated computer specialized for controlling the forklift 200. The computer referred to in this invention refers to an information processing device equipped with a control unit, a storage device, etc.

[0138] In this embodiment, the calculation unit 202 and the control unit 203 are mounted on the forklift 200, but for example, the calculation unit 202 and the control unit 203 may be mounted on a server or the like installed at a location remote from the forklift 200. In this case, information from multiple forklifts 200 can be integrated to more appropriately control the operation of each forklift 200. Note that the calculation unit 202 may be mounted on the forklift 200, and the control unit 203 may be mounted on a server.

[0139] FIG. 30 is a flowchart showing the flow of the control operation of the forklift 200 using the measurement system 500 of this embodiment. In step (hereinafter simply referred to as S) 11, control unit 203 starts taking pictures with camera 201 and moving forklift 200. For simplicity, in this example, the explanation will be given assuming that control unit 203 starts operation from a state where it knows the current position of forklift 200. In S12, the control unit 203 continues the photographing and movement. In S13, the control unit 203 determines whether or not the marker 1 has been detected based on the image captured by the camera 201. If the marker 1 has been detected, the process proceeds to S14, and if the marker 1 has not been detected, the process returns to S12 and the operation of detecting the marker 1 is repeated. In S14, the control unit 203 identifies on which palette P the marker 1 is provided by the graphic (identification mark 5). In S15, the calculation unit 202 calculates the relative position between the camera 201 and the marker 1 based on the mark 2 in the image captured by the camera 201. In S16, the control unit 203 controls the operation of the forklift 200 based on the calculation result of the calculation unit 202. For example, the control unit 203 controls the vertical position of the fork 200a and the position of the forklift 200. In S17, the control unit 203 determines whether or not to end the operation, and if the operation is to be continued, the process returns to S12, and if the operation is not to be continued, the operation is ended. The above steps are executed by a computer under an application program for the measurement system.

[0140] As described above, according to the measurement system 500 of this embodiment, by attaching the marker 1 to the pallet P, which is the object to be measured, the relative positional relationship between the pallet P and the forklift 200 can be measured (grasp) with extremely high accuracy, and the forklift 200 can be appropriately controlled.

[0141] Seventh embodiment FIG. 31 shows a seventh embodiment of a marker according to the present invention. The marker 1 of the seventh embodiment includes a mark 2 and an identification mark 5. The marker 1 of the seventh embodiment is similar to the marker of the sixth embodiment except that it does not include the moiré display areas 3 and 4. Therefore, parts that perform the same functions as those of the above-described embodiments are given the same reference numerals, and redundant explanations will be omitted as appropriate.

[0142] In the seventh embodiment, ArUco is used for the identification mark 5. ArUco is a technology that is publicly available at the following internet URL: “Detection of ArUco Markers” [searched on March 23, 2022], internet<URL:https: / / docs.opencv.org / 4.x / d5 / dae / tutorial_aruco_detection.html> This web page also describes how to measure position and orientation using ArUco. This measurement of position and orientation using ArUco allows for measurements similar to those using Mark 2 described above. Note that the measurement of position and orientation using Mark 2 allows for measurements with higher accuracy than the measurement of position and orientation using ArUco.

[0143] In this embodiment, the position and orientation are also measured using the mark 2. However, accurate measurement of the position and orientation using the mark 2 cannot be performed unless the mark 2 is properly photographed by the camera (photographing unit) 201. For example, if part of the mark 2 is dirty, obstructed by an obstacle, or blurred by light reflection, accurate measurement of the position and orientation cannot be performed.

[0144] Therefore, in this embodiment, in addition to measuring the position and orientation using the mark 2, the position and orientation are also measured using the identification mark 5 (ArUco). This measurement operation will be described later.

[0145] Furthermore, in this embodiment, since position and orientation measurements are also performed using the identification mark 5, the identification mark 5 has the same configuration as the mark 2 and is formed by a photolithography process in the same manner as the mark 2. This makes it possible to improve the accuracy of position and orientation measurements using the identification mark 5. The method of forming the identification mark 5 is the same as that of the mark 2, and is produced at the same time as the formation of the mark 2, so a detailed explanation will be omitted. Note that if convenience is prioritized over accuracy, the identification mark 5 may be formed by printing, or a label or sticker on which the identification mark 5 is separately printed may be attached.

[0146] FIG. 32 is a diagram showing a multi-faceted marker body 100 according to the seventh embodiment. The marker 1 of the seventh embodiment is manufactured by arranging a plurality of markers 1 side by side, that is, by manufacturing a multi-faceted marker body 100 having a plurality of markers 1 attached thereto. Then, the markers 1 are obtained by cutting out and individualizing the individual markers 1 from this multi-faceted marker body 100. In the marker polyhedron 100 shown in FIG. 32, four ArUco ID=0 are arranged in a row in the topmost row of markers 1 in the figure. Then, in the next row, four ArUco ID=1 are arranged in a row, in the row after that, four ArUco ID=2 are arranged in a row, in the row after that, four ArUco ID=3 are arranged in a row, in the row after that, four ArUco ID=4 are arranged in a row, and in the row after that, four ArUco ID=5 are arranged in a row. In other words, the ArUco ID is changed for each row. Note that this arrangement is not limited to this, and for example, ArUco (identification mark 5) with the same ID may be arranged for all markers 1 in one marker polyhedron 100, or ArUco (identification mark 5) with different IDs may be arranged for all markers 1.

[0147] FIG. 33 is a diagram showing a pallet P to which a marker 1 according to the seventh embodiment is attached. The marker 1 of this embodiment, like the sixth embodiment, can be attached to, for example, a pallet P used in logistics and used to identify the pallet P as an object to be detected. The configuration of the pallet P to which the marker 1 of the seventh embodiment is attached is the same as that of the sixth embodiment.

[0148] FIG. 34 is a diagram showing a measurement system 500 including the marker 1 of the seventh embodiment. The configuration of a measurement system 500 including a marker 1 of the seventh embodiment is the same as that of the measurement system 500 of the sixth embodiment, except for some differences in the processing in the calculation unit 202. The calculation unit 202 of this embodiment can perform calculations similar to calculation examples 1 to 4 of the sixth embodiment. At this time, in addition to measuring the position and orientation using the mark 2, measurement of the position and orientation using the identification mark 5 (ArUco) is also performed in parallel. If the position and orientation measurement using the mark 2 can be performed appropriately, the calculation unit 202 outputs the measurement results of the position and orientation using the mark 2. On the other hand, if the mark 2 is not properly photographed because a part of it is hidden, the calculation unit 202 outputs the measurement results of the position and orientation using the identification mark 5 (ArUco).

[0149] FIG. 35 is a flowchart showing the flow of the control operation of the forklift 200 using the measurement system 500 of this embodiment. In S21, the control unit 203 starts taking pictures with the camera 201 and moving the forklift 200. For simplicity, in this example, the explanation will be given assuming that the control unit 203 starts its operation from a state in which it knows the current position of the forklift 200. In S22, the control unit 203 continues the photographing and movement. In S23, the control unit 203 determines whether or not the marker 1 has been detected based on the image captured by the camera 201. If the marker 1 has been detected, the process proceeds to S24, and if the marker 1 has not been detected, the process returns to S22 and the operation of detecting the marker 1 is repeated. In S24, the control unit 203 identifies on which palette P the marker 1 is provided by the graphic (identification mark 5).

[0150] In S25, the calculation unit 202 uses the mark 2 to calculate the relative position between the marker 1 and the camera 201 (forklift 200) (hereinafter referred to as first calculation processing). In S26, the calculation unit 202 uses the graphic (identification mark 5) to calculate the relative position between the marker 1 and the camera 201 (forklift 200) (hereinafter referred to as second calculation processing). The first arithmetic processing in S25 and the second arithmetic processing in S26 are performed in parallel. Here, "the arithmetic processing is performed in parallel" does not only mean that the arithmetic processing is performed completely simultaneously in parallel (so-called parallel processing), but also means that the arithmetic processing is performed substantially simultaneously, such as the first arithmetic processing being performed immediately after the second arithmetic processing and the first arithmetic processing being performed immediately thereafter. In other words, this does not mean that only the first arithmetic processing is performed continuously and the second arithmetic processing is not usually performed, but rather that both arithmetic processings are performed continuously. By doing so, the arithmetic results of both the first arithmetic processing and the second arithmetic processing can be output immediately without a time lag.

[0151] In S27, the calculation unit 202 determines whether or not the relative position between the marker 1 and the camera 201 (forklift 200) has been calculated by the first calculation process. If the relative position has been calculated, the process proceeds to S28, and if the relative position has not been calculated, the process proceeds to S29. In S28, the calculation unit 202 outputs to the control unit 203 the calculation result of the relative position between the marker 1 and the camera 201 (forklift 200) obtained by the first calculation process. In S29, the calculation unit 202 outputs to the control unit 203 the calculation result of the relative position between the marker 1 and the camera 201 (forklift 200) obtained by the second calculation process. In S30, the control unit 203 controls the operation of the forklift 200 based on the calculation result of the calculation unit 202. For example, the control unit 203 controls the vertical position of the fork 200a and the position of the forklift 200. In S31, the control unit 203 determines whether or not to end the operation. If the operation is to be continued, the process returns to S22, and if the operation is not to be continued, the operation is ended. The above steps are executed by a computer under an application program for the measurement system.

[0152] FIG. 36 is a diagram showing a state in which part of the mark 2 is not properly photographed due to an obstacle. For example, as shown in FIG. 36, if two marks 2 cannot be properly photographed due to an obstacle S, the calculation unit 202 cannot calculate the relative position between the marker 1 and the camera 201 (forklift 200) using the mark 2. In such a case, the flow proceeds to S29, and the calculation unit 202 outputs the calculation result of the relative position between the marker 1 and the camera 201 (forklift 200) calculated using the graphic (identification mark 5) to the control unit 203. This makes it possible to avoid a situation where the calculation becomes impossible and the forklift 200 cannot be controlled. Note that if the obstacle S moves during subsequent control of the forklift 200, making it possible to properly photograph the mark 2, the determination in S27 becomes "YES," and control based on the first calculation process can be resumed.

[0153] As described above, according to the third embodiment, in addition to measuring the position and orientation using the mark 2 (first calculation process), measuring the position and orientation using a figure (identification mark 5) (second calculation process) is also performed in parallel, so that even in a situation where the mark 2 cannot be photographed properly, the measurement of the position and orientation can be continued without interruption.

[0154] (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.

[0155] (1) In the first to third embodiments, an example was described in which the mark 2 was black and its periphery was white. However, the present invention is not limited to this example, and the mark 2 may be white and its periphery may be black. More specifically, for example, in the first embodiment, the first layer 20 may be white, and the second layer 30 on the observation side may be black. 12 and 13 are diagrams showing a modified embodiment of the first embodiment in which the first layer 20 is white and the second layer 30 is black. As shown in Figure 13, by making the first layer 20 of the first embodiment white and the second layer 30 on the observation side black, the mark 2 becomes white like the marker 1 shown in Figure 12, and the surrounding area becomes black. Also, for example, in the third embodiment, the first layer 20C may be black, and the second layer 30C on the observation side may be white. 14 and 15 are diagrams showing a modified embodiment of the third embodiment in which the first layer 20C is black and the second layer 30C is white. As shown in Figure 15, by making the first layer 20C of the third embodiment black and the second layer 30 on the observation side white, the mark 2 becomes white like the marker 1C shown in Figure 14, and the surrounding area becomes black.

[0156] (2) In the first to third embodiments, an example has been described in which the mark 2 is displayed using two colors, black and white. However, the present invention is not limited to this, and other colors, such as blue and yellow, may be combined. Furthermore, a configuration in which more layers are stacked so that the mark 2 is observed in three or more colors may be used, for example, by adding a third layer observed in a third color. Furthermore, the color difference in the present invention is not limited to the color difference expressed by a combination of RGB, but may also include the difference expressed by a single color with multiple gradations.

[0157] (3) In the first to third embodiments, examples were described in which the mark 2 was observable under visible light. However, the present invention is not limited to this. For example, the mark 2 may be detected using light in a specific wavelength range, such as the infrared light range (near-infrared wavelength range of 780 nm or more). More specifically, the mark 2 may be observable in the near-infrared light range, but may be unobservable or inconspicuous in the white light (visible light) range. If the mark 2 is formed from a near-infrared absorbing material, the mark 2 can be identified by a near-infrared receiving element only when irradiated with near-infrared light, but not by the human eye. Known near-infrared absorbing materials, such as ITO, ATO, cyanine compounds, phthalocyanine compounds, dithiol metal complexes, naphthoquinone compounds, diimmonium compounds, and azo compounds, can be used. This allows the marker 1 (1B) to be used in applications where it is desirable to make the marker 1 (1B) less conspicuous. In such a case, it is desirable that when observed using light in a specific wavelength range, the contrast value between the first color of the first layer 20 and the second color of the second layer 30 is 0.26 or more, and the contrast value between the first color and the second color under visible light is 1.0 or less. By doing so, it is possible to achieve position detection that is inconspicuous under visible light and that is highly accurate under light in a specific wavelength range.

[0158] (4) In the first to third embodiments, the protective layer 70 is attached by the adhesive layer 60. However, the present invention is not limited to this. For example, the protective layer may be directly laminated on the second layer 30, or the protective layer may be omitted depending on the usage environment.

[0159] (5) In the first to third embodiments, the second exposure step of exposing the mark pattern onto the second layer 30 has been described using an example of using a mask M. However, the present invention is not limited to this, and the mark pattern may be exposed by a direct writing method using laser light, for example.

[0160] (6) In the first to third embodiments, an example was described in which the first layer 20 was observable as a mark having an independent shape. However, this is not limiting, and for example, the second layer 30 may be configured to be observable as a mark having an independent shape. In addition, in this regard, the resist material forming the second layer 30 may be either positive or negative.

[0161] (7) In the first to third embodiments, a layer for improving adhesion, a layer for improving surface properties, or a layer for diffusing light to provide anti-glare properties may be inserted between each layer or on the outermost surface, as appropriate.

[0162] (8) In the third embodiment, an example was described in which the planarizing layer 91 was provided. Such a planarizing layer may also be provided in the first embodiment. FIG. 16 is a cross-sectional view showing a modified embodiment in which a planarizing layer 91 is provided in the opening 30a of the second layer 30 of the first embodiment. As shown in FIG. 16, by providing a planarizing layer 91 in the opening 30a of the second layer 30, it is possible to prevent the occurrence of voids. Furthermore, in the form of Figure 16 and the third embodiment described above, an example is shown in which the height of the planarization layer 91 is lower than that of the second layers 30, 30C, but the planarization layer 91 may be slightly higher than the second layers 30, 30C, or more preferably, it may be the same height as the second layers 30, 30C.

[0163] (9) In the fourth embodiment, an example was described in which the first layer 20 is black and the second layer 30 is white. However, this is not limiting, and for example, the first layer 20 may be white and the second layer 30 may be black. Alternatively, the combination is not limited to black and white, and other colors such as blue and yellow may be combined.

[0164] (10) In the fourth embodiment, an example was described in which the black portion of the mark 2 and the first pattern 23 were formed by the first layer 20. However, this is not limiting, and for example, the mark 2 and the first pattern 23 may be provided on different layers.

[0165] (11) In the fourth embodiment, the protective layer 70 is attached by the adhesive layer 60. However, the present invention is not limited to this. For example, the protective layer may be directly laminated on the second layer 30, or the protective layer may be omitted depending on the usage environment.

[0166] (12) In the fourth embodiment, an example was described in which the moiré display area 3 and the moiré display area 4 are arranged so that their longitudinal directions are perpendicular to each other. However, this is not limiting, and for example, an additional moiré display area may be added. In this case, the longitudinal direction of the additional moiré display area may be arranged so that it intersects with the moiré display area 3 and the moiré display area 4 at an angle of 45 degrees, for example. By using such a configuration, the accuracy of position detection can be further improved.

[0167] (13) In the fifth embodiment, the light diffusion layer is described as being formed by attaching a sheet-like member. However, the present invention is not limited to this, and the light diffusion layer may be formed by applying a resin or the like to form the light diffusion layer.

[0168] (14) In the fifth embodiment, the light diffusion layer has been described as having fine irregularities on the surface. However, the light diffusion layer may have light diffusion particles inside, or may have both fine irregularities on the surface and light diffusion particles inside.

[0169] (15) In the fifth embodiment, the light diffusion layer is partially provided in an island shape. However, the present invention is not limited to this, and the light diffusion layer may be provided over the entire surface of the marker.

[0170] (16) In the fifth embodiment, an example was described in which the first layer 20 is black and the second layer 30 is white. This is not a limitation, but for example, as shown in FIG. 26 , the first layer 20 may be white and the second layer 30 may be black. The combination is not limited to black and white, and may include other colors, such as blue and yellow. Furthermore, a configuration in which more layers are stacked so that three or more colors are observed may be added, for example, by adding a third layer observed in a third color. Furthermore, the color differences in the present invention are not limited to differences in color expressed by a combination of RGB, but may also include differences due to multi-tone expression of a single color.

[0171] (17) In each embodiment, an example has been described in which both the first layer 20 and the second layer 30 are made of a resist material. However, this is not limiting, and the first layer 20 and the second layer 30 may be made by, for example, laminating a thermosetting resin on the necessary portions by an inkjet method. Even in such a case, the linear expansion coefficient of the base layer 10 is 10 × 10 -6 / °C or less, sufficient accuracy can be ensured depending on the application.

[0172] (18) In the sixth embodiment, an example was given in which the measurement system of the present invention was applied to the control of a forklift 200. However, the present invention is not limited to this example and can be applied to various fields. For example, markers 1 may be placed at various locations indoors and the measurement system may be applied to the movement control of various conveyance vehicles, robots, etc. that move indoors. Furthermore, cameras may be placed at various locations indoors and markers may be placed on various conveyance vehicles, robots, etc. that move indoors, and the present invention may be applied to the movement control of various conveyance vehicles, robots, etc. that move indoors. Furthermore, the present invention is not limited to indoor use and may be applied to the movement control of drones, etc. outdoors. Furthermore, the present invention may be used for various measurements of construction sites, infrastructure such as dams and bridges, etc., without movement control.

[0173] (19) In the sixth embodiment, an example was described in which the measurement system of the present invention was applied to the control of the forklift 200. However, the present invention is not limited to this, and the system may be configured to only obtain measurement results without including a control unit.

[0174] (20) In the seventh embodiment, an example was described in which measurement of position and orientation using the mark 2 (first arithmetic processing) and measurement of position and orientation using a figure (identification mark 5) (second arithmetic processing) were performed in parallel. This is not limiting, and for example, in an application in which the time lag in switching between calculations is not an issue, only the first arithmetic processing may be performed continuously, and the second arithmetic processing may not normally be performed, with switching to the second arithmetic processing only when the first arithmetic processing cannot be performed.

[0175] (21) In the seventh embodiment, an example was described in which the marker 1 was attached to the pallet P. However, the present invention is not limited to this example, and the marker 1 may be attached to a shelf on which items are displayed. FIG. 37 is a diagram showing a first modified mode of use of the marker 1 of the seventh embodiment. In the example shown in Figure 37, a marker 1 is attached to the intersection position (intersection point) of a shelf board T1 of a shelf T and a pillar T2 of the shelf T. Each ArUco as an identification mark 5 provided on the marker 1 is assigned a different ID. In this case, the camera, calculation unit, and control unit are provided in the automatic conveying machine (robot) 300, and the automatic conveying machine 300 can accurately grasp the intersection position (intersection point) with the column T2 of the shelf T by photographing the marker 1 and measuring the position of the marker 1. Furthermore, the shelf board can be identified using information obtained from the identification mark 5, and the automatic conveying machine 300 is automatically controlled to move to the appropriate position, and can automatically perform tasks such as replenishing, replacing, and picking up items placed on the shelf T. This configuration can be applied to product shelves in a store, for example, or to shelves in a logistics warehouse or factory warehouse.

[0176] (22) In the seventh embodiment, an example was given in which the marker 1 was attached to the pallet P. However, the present invention is not limited to this, and the marker 1 may be attached to, for example, the windshield of a car. FIG. 38 is a diagram showing a second modified mode of use of the marker 1 of the seventh embodiment. FIG. 38 shows a situation in which a car 401 and a car 402 are parked in a parking lot. In the example shown in FIG. 38, the identification mark 5 of the marker 1 attached to the windshield of the car 401 and the identification mark 5 of the marker 1 attached to the windshield of the car 402 have different IDs.

[0177] A camera (photographing unit) 450 is also installed in the parking lot, photographing cars parked therein and connected to a calculation unit (not shown). Data such as the car's shape, weight, license plate number, and owner are associated with each ID of the identification mark 5 of each marker 1. Therefore, parking fee payment can be automated based on the photographing results taken by the camera 450. By using the marker 1 to measure the car's location, it is possible to accurately determine which car is parked in which location. Therefore, if the car is parked in the wrong location, a notification to that effect can be issued, and an attendant can be called to prompt action. In the case of a car, it is expected that the windshield will become dirty with fallen leaves, mud, etc.; however, even in such a case, by performing both the first calculation process and the second calculation process, it is possible to avoid situations where the car's location cannot be measured. Furthermore, unlike a car license plate, the ArUco identification mark 5 cannot be easily deciphered by the average person at a glance, which contributes to protecting privacy. Although systems that read license plates and use them for toll payment are already in practical use, license plates cannot accurately measure position and orientation. By using Marker 1, on the other hand, the position of a car can be accurately determined throughout the entire parking lot.

[0178] The embodiments and modifications may be used in combination as appropriate, but detailed description thereof will be omitted. The present invention is not limited to the embodiments described above. [Explanation of symbols]

[0179] 1, 1B, 1C markers 2 marks 3, 4 Moire display area 5 Identification Mark 10 Base material layer 20, 20C First layer 21 1st display line 22 1st hidden area 23 First Pattern 30, 30C Second layer 30a opening 31 Opening 32 Opening 40 Third Layer 41 2nd display line 42 2nd hidden area 43 Second Pattern 50 reflective layer 60 Adhesive layer 70 protective layer 71 Resin base material layer 72 Surface layer 80 Light diffusion layer 81 Resin base material layer 82 Surface layer 91 Planarization layer 92 Middle Class 100 marker polyhedron 200 forklifts 201 Camera (photography section) 202 Arithmetic section 203 Control Unit 300 Automatic Transfer Machine 401, 402 Automobiles 450 Camera (photography section) 500 Measurement System

Claims

1. Marker and an imaging unit that images the marker; a calculation unit that calculates at least one of the relative positional relationship between the image capturing unit and the marker, the dimensions of an object near the marker or the distance between designated positions, the distance between a plurality of the markers, and the attitude of the marker, using the image of the marker captured by the image capturing unit; A measurement system comprising: The marker is a substrate layer; a first layer laminated on the observation side of the base layer and observed to have a first color; a second layer partially laminated on the observation side of the first layer, observed to have a second color different from the first color, and partially concealing the first layer; Equipped with the first layer is visible in an area where the second layer is not deposited; the second layer is made of a resist material. Measurement system.

2. 2. The measurement system of claim 1, the first layer is made of a resist material; A measurement system characterized by:

3. Marker and an imaging unit that images the marker; a calculation unit that calculates at least one of the relative positional relationship between the image capturing unit and the marker, the dimensions of an object near the marker or the distance between designated positions, the distance between a plurality of the markers, and the attitude of the marker, using the image of the marker captured by the image capturing unit; A measurement system comprising: The marker is a substrate layer; a first layer that is laminated on the observation side of the base material layer and that is observed to have a first color and is laminated on the entire surface of the base material layer; a second layer partially laminated on the observation side of the first layer, observed to have a second color different from the first color, and partially concealing the first layer; Equipped with the first layer is visible in an area where the second layer is not deposited; The base layer has a linear expansion coefficient of 10×10 －６ / °C or less, Measurement system.

4. The measurement system according to any one of claims 1 to 3, the substrate layer is made of glass; A measurement system characterized by:

5. The measurement system according to any one of claims 1 to 3, one of the first layer or the second layer is observable as a separate mark; The marks are arranged in a number of three or more with intervals between them; A measurement system characterized by:

6. 6. The measurement system according to claim 5, There are symbols for identification, the calculation unit identifies the marker by referring to the graphic; A measurement system characterized by:

7. 7. The measurement system according to claim 6, The calculation unit a first calculation process for calculating, based on an image of the mark included in the image of the marker, at least one of a relative positional relationship between the image capturing unit and the marker, a dimension of an object near the marker or a distance between designated positions, a distance between a plurality of the arranged markers, and an attitude of the marker; a second calculation process for calculating at least one of the relative positional relationship between the image capturing unit and the marker, the dimensions of an object near the marker or the distance between designated positions, the distance between a plurality of the markers, and the attitude of the marker, based on an image of the identification graphic included in the image of the marker; To do so, A measurement system characterized by:

8. 8. The measurement system according to claim 7, the calculation unit outputs a calculation result of the first calculation process when the calculation can be performed appropriately by the first calculation process, and outputs a calculation result of the second calculation process when the calculation cannot be performed appropriately by the first calculation process; A measurement system characterized by:

9. 9. The measurement system according to claim 8, the calculation unit performs the first calculation process and the second calculation process in parallel; A measurement system characterized by:

10. The measurement system according to any one of claims 1 to 3, a control unit that performs control based on the calculation result of the calculation unit; A measurement system characterized by:

11. A measurement method for the measurement system according to any one of claims 1 to 3, comprising: a step of the photographing unit photographing the marker; the calculation unit uses the images of the markers photographed by the photographing unit to calculate at least one of the relative positional relationship between the photographing unit and the markers, the dimensions of objects near the markers or the distance between designated positions, the distance between the multiple markers, and the attitudes of the markers; A measurement method in a measurement system comprising:

12. A program for the measurement system according to any one of claims 1 to 3, On the computer, a step of the photographing unit photographing the marker; a step in which the calculation unit calculates, using the images of the markers photographed by the photographing unit, at least one of the relative positional relationship between the photographing unit and the markers, the dimensions of objects or the distance between designated positions near the markers, the distance between the multiple markers arranged, and the attitude of the markers; A program for the measurement system to execute the above.

Images