Patent Publication Number: US-2021164774-A1

Title: Marker

Description:
TECHNICAL FIELD 
     The present invention relates to a marker. 
     BACKGROUND ART 
     As a marker (which is also called “image indicator”) employing a combination of a lens and a pattern, an image display sheet including a lenticular lens and an image formation layer is known. The lenticular lens has a structure in which a plurality of cylindrical lenses are arranged side by side. In addition, the image formation layer is a pattern corresponding to each cylindrical lens. When the marker is viewed from the side of the convex surface parts of the cylindrical lenses, the image of the pattern moves or deforms depending on the viewing positions. In the technical fields of augmented reality (AR), robotics and the like, the marker is useful as a measuring device for recognizing the position, the orientation of an object and the like, and for such a use, the arrangement of the pattern and the like are conventionally studied (see, e.g., PTL 1 and PTL 2). 
     CITATION LIST 
     Patent Literature 
     PTL 1 
     
         
         Japanese Patent Application Laid-Open No. 2013-025043 
       
    
     PTL 2 
     
         
         Japanese Patent Application Laid-Open No. 2012-145559 
       
    
     SUMMARY OF INVENTION 
     Technical Problem 
     In a marker, the position, shape and the like of the image to be observed are important points, and therefore it is necessary to form each pattern at a specific position with respect to the vertex of the lens in the plane direction of the cylindrical lens. Downsizing of the marker is desirable; however, the allowable error in the plane direction of the pattern decreases as the maker is downsized, and, for example, the allowable error in the plane direction of the pattern of a downsized marker is about several micrometers. 
     In addition, it is conceivable to integrally form a marker by injection molding. In this case, naturally, the lens part corresponding to the lens and the pattern part corresponding to the pattern are integrally molded with respective metal-mold pieces. In the case where a marker is produced by injection molding, the metal-mold pieces are aligned by repeating trial moldings until a desired shape of the marker is obtained. 
     However, when the pattern part is observed from the lens part side, the position of the pattern part with respect to the lens part cannot be correctly determined due to refraction at the lens part since the lens part and the pattern part are disposed on opposite sides in the marker. As a result, the metal mold pieces cannot be highly precisely aligned in injection molding, making it difficult to produce a highly accurate marker. 
     An object of the present invention is to provide a marker which can be precisely produced. 
     Solution to Problem 
     A marker of an embodiment of the present invention includes: a convex lens part made of an optically transparent resin and including a first surface and a second surface disposed on a side opposite to the first surface, the first surface including a convex surface part and a flat surface part, the second surface including a first region and a second region which is a region other than the first region in the second surface; a detection object part formed in one of the first region and the second region, or in both of the first region and the second region; and a positioning part formed on the second surface in a region corresponding to the flat surface part, and configured to indicate a position of the first region with respect to the convex surface part. The first region is a recess or a protrusion disposed on the second surface in a region corresponding to the convex surface part. 
     Advantageous Effects of Invention 
     According to the present invention, a highly accurate marker can be produced can be provided. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIGS. 1A and 1B  illustrate a configuration of a marker according to Embodiment 1 of the present invention; 
         FIG. 2  is a cross-sectional view of a metal mold for manufacturing a lenticular lens part of a marker by injection molding; 
         FIGS. 3A and 3B  illustrate a method for aligning a metal mold; 
         FIGS. 4A and 4B  illustrate a configuration of a marker according to a modification of Embodiment 1 of the present invention; 
         FIGS. 5A and 5B  illustrate a configuration of a marker according to Embodiment 2 of the present invention; 
         FIGS. 6A and 6B  illustrate a configuration of a marker according to Embodiment 3 of the present invention; 
         FIGS. 7A and 7B  illustrate a configuration of a marker according to Embodiment 4 of the present invention; 
         FIG. 8  illustrates a configuration of a marker according to Embodiment 5 of the present invention; 
         FIGS. 9A to 9C  illustrate a configuration of a marker according to Embodiment 6 of the present invention; 
         FIGS. 10A to 10D  illustrate a configuration of a marker according to Embodiment 7 of the present invention; 
         FIGS. 11A to 11D  illustrate a configuration of a marker according to Embodiment 8 of the present invention; and 
         FIGS. 12A to 12D  illustrate a configuration of a marker according to Embodiment 9 of the present invention. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Markers according to embodiments of the present invention are described below with reference to the accompanying drawings. 
     Embodiment 1 
     (Configuration of Marker) 
       FIGS. 1A and 1B  illustrate a configuration of marker  100  according to Embodiment 1 of the present invention.  FIG. 1A  is a plan view of marker  100  according to Embodiment 1 of the present invention, and  FIG. 1B  is a front view of marker  100 . 
     As illustrated in  FIGS. 1A and 1B , marker  100  includes lenticular lens part  120 , and detection object part (coating film)  150 . 
     Lenticular lens part (convex lens part)  120  includes first surface (front surface)  123 , and second surface (rear surface)  124  disposed on the opposite side of first surface  123 . First surface  123  includes a plurality of convex surface parts  131 , and two flat surface parts  134 . In addition, second surface  124  includes first region  141 , and second region  142 , which is a region other than first region  141  in second surface  124 . The material of lenticular lens part  120  is, for example, a transparent resin having optical transparency, such as polycarbonate and acrylic resin. 
     Convex surface part  131  extends in a first direction (the Y direction in  FIG. 1 ) perpendicular to the thickness direction of lenticular lens part  120 . Convex surface part  131  is a curved surface that includes ridgeline  133  linearly extending in the first direction, and has a curvature only in a second direction (the X direction in  FIG. 1 ) perpendicular to the thickness direction of lenticular lens part  120  and the first direction. A plurality of convex surface parts  131  are arranged in the second direction such that ridgelines  133  are parallel to each other. In addition, side surface parts  132  that are orthogonal to the first direction are disposed at the both ends of convex surface parts  131  in the first direction. 
     Two adjacent convex surface parts  131  of the plurality of convex surface parts  131  may be separated from each other, or may be disposed with no gap therebetween. In the present embodiment, two adjacent convex surface parts  131  of the plurality of convex surface parts  131  are disposed with no gap therebetween. 
     Convex surface parts  131  have the same size. For example, width W 1  (the length in the first direction) of each convex surface part  131  is 370 μm, and the pitch P CL  of convex surface parts  131  is 370 μm. The term “pitch” is the distance between ridgelines  133  (or central axes CA) of convex surface parts  131  adjacent to each other in the second direction, and is also the length (width) of convex surface part  131  in the second direction. The term “central axis CA of convex surface part  131 ” is a straight line passing through the center of convex surface part  131  and extending along a third direction (the Z direction in  FIG. 1 ) perpendicular to the first direction and the second direction in plan view of convex surface part  131 . 
     The cross-sectional shape of convex surface part  131  in a direction along a virtual plane perpendicular to a virtual line extending along the first direction may be a curve or an arc. The term “curve” is a curve other than an arc, and is, for example, a curve composed of arcs having different curvature radiuses. Preferably, in the present embodiment, the curve is a curve whose curvature radius increases in the direction away from the ridgeline of convex surface part  131 . In addition, in the present embodiment, convex surface parts  131  have the same the cross-sectional shape in the first direction. 
     In the first direction, flat surface part  134  is disposed outside convex surface part  131 . Flat surface part  134  is connected with side surface part  132 , and is parallel to a virtual plane including a virtual line along the first direction and a virtual line along the second direction. 
     First region  141  is disposed in a part of a region corresponding to convex surface part  131  in second surface  124 . In plan view of lenticular lens part  120 , first region  141  is disposed along the first direction. First region  141  may be a recess or a protrusion. In the present embodiment, first region  141  is a recess. In addition, in the present embodiment, the region other than first region  141  in second surface  124  is second region  142 . The shape of first region  141  is not limited as long as detection object part  150  forms an optically detectable image having a predetermined width when viewed along the third direction (thickness direction) orthogonal to the first direction and the second direction. In the present embodiment, in plan view, first region  141  has a rectangular shape elongated in the first direction. 
     In the first direction, the both ends of the recess that serves as first region  141  are located outside the both ends of convex surface part  131 . Specifically, the both ends of the recess that serves as first region  141  are disposed at positions corresponding to flat surface parts  134 . That is, in the first direction, the recess that serves as first region  141  is longer than convex surface part  131 . The recess that serves as first region  141  includes top surface  143 , a pair of first inner surfaces  144  that are opposite to each other in the short direction, and a pair of second inner surfaces  145  that are opposite to each other in the longitudinal direction. Top surface  143  is parallel to second region  142  and flat surface part  134 . In addition, the pair of first inner surfaces  144  and the pair of second inner surfaces  145  are perpendicular to second region  142 . 
     In addition, the depth of the recess that serves as first region  141  is not limited as long as ease of application of the coating material and a desired function (indication of images) can be ensured. The range of the depth of the recess that serves as first region  141  may be 10 to 100 μm. In the present embodiment, the depth of the recess that serves as first region  141  is 10 μm. Length (width) W 2  of the recess that serves as first region  141  in the second direction is 45 μm, for example. The smaller the width W 2  of first region  141  with respect to P CL , the higher the contrast of the image appearing on convex surface part  131  side tends to be. The larger the width W 2  of first region  141  with respect to P CL , the easier the production of first region  141  and detection object part  150 . Preferably, the ratio of width W 2  of first region  141  to pitch P CL  (W 2 /P CL ) is 1/100 to 1/5 in view of obtaining a sufficiently clear image. 
     First regions  141  are positioned in respective convex surface parts  131  such that images of first regions  141  are observed at a center portion of lenticular lens part  120  in the second direction when marker  100  is observed from first surface  123  side at the center of convex surface parts  131  in the second direction. 
     For example, in the second direction, first region  141  corresponding to convex surface part  131  located at the center of lenticular lens part  120  (convex surface part  131  of n=0 in  FIG. 1B ) is disposed such that center C 0  thereof is located on central axis CA of convex surface part  131  of n=0. 
     The center-to-center distance (|C n −C n−1 |) of first regions  141  corresponding to two convex surface parts  131  adjacent to each other in the second direction is represented by P CL +nG μm. As described above, P CL  is the distance between of ridgelines  133  of two convex surface parts  131  adjacent to each other in the second direction. In addition, G is a predetermined distance (e.g. 8 μm) from P CL  in the second direction for ensuring the desired optical effect of images. Further, n represents an order of a certain convex surface part  131  with respect to 0th convex surface part  131  located at the center in the second direction. 
     With this configuration, first regions  141  corresponding to convex surface parts  131  other than convex surface part  131  located at the center (n=0) are disposed outside central axes CA of respective convex surface parts  131  in the second direction. 
     Detection object part  150  is formed in first region  141 . Detection object part  150  is a solidified black liquid coating material, for example. 
     Detection object part  150  is produced through application and solidification of a coating material. The black liquid coating material has fluidity, and is a liquid composition or powder. The method of application and solidification of the coating material may be appropriately selected from publicly known methods in accordance with the coating material. Examples of the application method of the black liquid coating material include spray coating and screen printing. Examples of the solidification method of the black liquid coating material include drying of a black liquid coating material, curing of a curable composition (such as radical polymerizable compound) in a black liquid coating material, and baking of powder. 
     Detection object part  150  forms an optically discriminable portion. The term “optically discriminable” means that detection object part  150  and another portion are clearly different in their optical characteristics. The term “optical characteristics” means, for example, the degrees of the color such as brightness, saturation and hue, or the optical intensity such as luminance The term “difference” may be appropriately set in accordance with the use of marker  100 , and may be a difference which can be visually checked, or a difference which can be confirmed with an optical detection apparatus, for example. In addition, the difference may be a difference which can be directly detected from detection object part  150 , or a difference which can be detected through an additional operation such as irradiation of an UV lamp as in the case where detection object part  150  is a transparent film that emits fluorescence, for example. 
     Positioning part  160  indicates the position of first region  141  with respect to convex surface part  131 . Positioning part  160  is formed in the region corresponding to flat surface part  134  in second surface  124 . The shape of positioning part  160  is not limited as long as the above-described function can be ensured. In the present embodiment, in the first direction, positioning part  160  is a recess that is continuous to first region  141  and extends to the outside of convex surface part  131 . In this manner, the recess that serves as first region  141  and the recess that serves as positioning part  160  are integrally formed, and thus the positional relationship of the recesses can be precisely set. It is to be noted that positioning part  160  is formed in the region corresponding to flat surface part  134  in second surface  124  such that the position corresponding to first region  141  can be correctly set even when the shape and the position of positioning part  160  are different. 
     When marker  100  is placed on a white object, light which is incident on first region  141  through convex surface part  131  is absorbed by detection object part  150 , whereas light which is incident on other portions (second region  142 ) through convex surface part  131  is generally reflected by the object surface. As a result, an image of a colored (black) line of detection object part  150  is projected on convex surface part  131  with a white background. 
     Since first regions  141  are appropriately disposed in accordance with their distances from the center of marker  100  in the second direction, a black collective image that is a group of the black line images is observed in the entirety of lenticular lens part  120  when marker  100  is observed from first surface  123  side of lenticular lens part  120 . 
     For example, when marker  100  is viewed from the center of lenticular lens part  120  in the second direction, the black collective image is observed at a center portion in the second direction. When marker  100  is observed from a different angle, the collective image is observed at a different position in the second direction depending on the angle. That is, the angle of the observation position of marker  100  is determined based on the position of the collective image in the second direction. 
     Manufacturing Method of Marker 
     Marker  100  can be produced by the following method.  FIG. 2  is a cross-sectional view of metal mold  170  for manufacturing lenticular lens part  120  of marker  100  by injection molding. 
     First, lenticular lens part  120  is molded by injection molding with a transparent resin. First, metal mold  170  is aligned and clamped (mold clamping step). Next, a molten resin is supplied to fill metal mold  170  (filling step). Then, with metal mold  170  filled with the molten resin, natural cooling is performed while holding the pressure (pressure holding step). Further, the clamped metal mold  170  is opened (mold opening step). Finally, an injection-molded article (lenticular lens part  120 ) is removed from the open metal mold  170  (removing step). It is to be noted that the injection-molded article is produced with metal mold  170  illustrated in  FIG. 2 . Metal mold  170  includes upper mold  171  and lower mold  172 . Upper mold  171  includes recessed surface part  173  having a shape corresponding to convex surface part  131 , and flat surface  174  having a shape corresponding to flat surface part  134 . Lower mold  172  includes linear projection  175  having a shape corresponding to first region  141 . Through the above-mentioned steps, lenticular lens part  120  including convex surface part  131  and flat surface part  134  on first surface  123  side (front side) and first region  141  and second region  142  on second surface  124  side (rear side) is obtained in the form of an integrally molded-article of a transparent resin. The mold clamping step is an important step of the manufacturing method of lenticular lens part  120  by injection molding, and therefore the mold clamping step is elaborated later. 
     Next, a coating material is applied to first region  141  to produce detection object part  150 . To be more specific, the coating material is supplied to the entirety of first region  141  or to a certain depth of first region  141 , and then the coating material is solidified. In this manner, detection object part  150  that has a thickness equal to the supplied depth of the coating material and covers top surface  143  of first region  141  is produced. 
     Now, the mold clamping step is elaborated.  FIGS. 3A and 3B  illustrate a method for aligning metal mold  170 .  FIG. 3A  is a plan view of an injection-molded article in which the positions of convex surface part  131  and first region  141  are shifted in the second direction, and  FIG. 3B  is an enlarged view of the region enclosed by the broken line in  FIG. 3A . Here, to simplify the description, the method is described based on the case where the positions of convex surface part  131  and first region  141  are shifted only in the second direction. 
     In the mold clamping step, metal mold  170  is aligned so as to produce a desired injection-molded article (lenticular lens part  120 ). As described above, the position and the shape of images to be observed in marker  100  are important points. That is, the position of first region  141  with respect to convex surface part  131  is an important factor. However, when aligning recessed surface part  173  corresponding to convex surface part  131  and linear projection  175  corresponding to first region  141  in the mold clamping step, recessed surface part  173  and linear projection  175  cannot be visually recognized when upper mold  171  and lower mold  172  are joined together. Consequently, the positional relationship between recessed surface part  173  and linear projection  175  cannot be correctly determined, and metal mold  170  cannot be accurately aligned. In view of this, in the present embodiment, a trial molding is conducted, and metal mold  170  is accurately aligned based on the injection-molded article obtained through the trial molding. 
     The method for aligning metal mold  170  includes a first step of acquiring location information of convex surface part  131  in an injection-molded article obtained through a trial molding, a second step of acquiring location information of positioning part  160  in the injection-molded article obtained through the trial molding, a third step of acquiring information for adjusting metal mold  170  based on the position of convex surface part  131  and the position of positioning part  160 , and a fourth step of aligning metal mold  170  so as to set a predetermined positional relationship between convex surface part  131  and first region  141  after the aligning. It is to be noted that the information of the position where first region  141  should be located with respect to convex surface part  131 , and the information of the position of positioning part  160  with respect to first region  141  are set by design. 
     In the first step, for example, an injection-molded article is imaged from first surface  123  side with an appropriate image pickup means, and the location information of convex surface part  131  is acquired. The location information of convex surface part  131  is not limited as long as the position of convex surface part  131  can be specified. For example, the location information of convex surface part  131  may be the location information of central axis CA of convex surface part  131 , or the location information (P 0A ) of the center of side surface part  132  in plan view of lenticular lens part  120 . In the present embodiment, the location information of convex surface part  131  is location information (P 0A ) of the center of side surface part  132  in plan view of lenticular lens part  120 . The location information of the center (P 0A ) of side surface part  132  may be acquired by any method. The location information (P 0A ) of the center of side surface part  132  may be determined by acquiring location information (P 1A , P 2A ) of end portions of two long sides convex surface part  131 , and by determining the center of the two positions, for example. 
     In the second step, for example, the injection-molded article is imaged from the position same as in the first step with the same image pickup means, and the location information of positioning part  160  is acquired. The location information of positioning part  160  is not limited as long as the position of positioning part  160  can be specified. The location information of positioning part  160  may be the location information of the center of positioning part  160 , or the location information (P 0B ) of the center of end portion of positioning part  160 , for example. In the present embodiment, the location information of positioning part  160  is the location information (P 0B ) of the center of the end portion of positioning part  160 . The location information (P 0B ) of the center of the end portion of positioning part  160  may be acquired by any method. The location information (P 0B ) of the center of the end portion of positioning part  160  may be determined by acquiring location information (P 1B , P 2B ) of end portions of the two long sides of positioning part  160 , and by determining the center of the two positions, for example. At this time, the location information of positioning part  160  is correctly detected since the information is detected through flat surface part  134 , not through convex surface part  131 . 
     In the third step, information for aligning metal mold  170  is acquired from the location information of convex surface part  131  (P 0A ) determined in first step, and the location information of positioning part  160  (P 0B ) determined in the second step. The information for aligning metal mold  170  is the moving direction and the moving distance of metal mold  170 . As seen in  FIG. 3B , the two points (the center of side surface part  132  and the center of the end portion of positioning part  160 ) which should be located at the same position in the second direction (the X direction) are shifted in the second direction (the X direction). Accordingly, upper mold  171  or lower mold  172  would need to be moved in the second direction by a predetermined distance. 
     In the fourth step, metal mold  170  is moved by the direction and the distance determined in the third step such that first region  141  and convex surface part  131  after the injection molding are set in a desired positional relationship. 
     Through the above-mentioned procedure, metal mold  170  can be accurately aligned by moving metal mold  170  based on the location information of convex surface part  131  and positioning part  160 . 
     Effect 
     As described above, marker  100  according to the present embodiment includes positioning part  160  that can be detected through flat surface part  134  that can be detected through flat surface part  134 , and thus metal mold  170  can be accurately aligned based on first region  141  and convex surface part  131  of lenticular lens part  120  after the injection molding. Accordingly, highly accurate marker  100  can be obtained. 
     Modification Marker  100 ′ according to a modification of Embodiment 1 differs from marker  100  according to Embodiment 1 only in configuration of lenticular lens part  120 ′. In view of this, the configurations similar to those of light emitting device  100  according to Embodiment 1 will be denoted with the same reference numerals, and the description thereof will be omitted. 
       FIGS. 4A and 4B  illustrate a configuration of marker  100 ′ according to the modification of Embodiment 1 of the present invention.  FIG. 4A  is a plan view of marker  100 ′ according to the modification of Embodiment 1, and  FIG. 4B  is a front view of marker  100 ′. 
     As illustrated in  FIGS. 4A and 4B , lenticular lens part  120 ′ according to the modification of Embodiment 1 includes first surface  123  and second surface  124 ′. First surface  123  includes a plurality of convex surface parts  131 , and two flat surface parts  134 . Second surface  124 ′ includes first region  141 ′, and second region  142 ′ that is regions other than first region  141 ′ in second surface  124 ′. 
     The shape of first region  141 ′ includes top surface  143 ′, a pair of first outer surfaces  144 ′ that are opposite to each other in the short direction, and a pair of second outer surfaces  145 ′ that are opposite to each other in the longitudinal direction. Top surface  143 ′ is parallel to second region  142 ′. In addition, the pair of first outer surfaces  144 ′ and the pair of second outer surfaces  145 ′ are perpendicular to second region  142 ′. That is, the configuration is identical to that of marker  100  except that first region  141 ′ is a protrusion, and second region  142 ′ is a surface that is flat with respect to first region  141 ′. 
     Detection object part  150 ′ is formed at top surface  143 ′ of first region  141 ′. In view of ensuring ease of application of a coating material and a desired function (indication of images), the range of the height of first region  141 ′ may be 10 to 100 μm, and is for example 10 μm. 
     Positioning part  160 ′ is a protrusion that is formed continuously from first region  141 ′ so as to extend outward relative to convex surface part  131  in the first direction. 
     Marker  100 ′ is also produced by producing lenticular lens part  120 ′ by injection molding with an appropriate metal mold, and by applying a coating material to top surface  143 ′ of an integrally molded-article so as to produce detection object part  150 ′. 
     In addition, marker  100 ′ according to the modification also can correctly align metal mold  170  based on the location information of convex surface part  131 ′ and positioning part  160 ′. It is to be noted that also with marker  100 ′ according to the modification of Embodiment 1, the location information of positioning part  160 ′ can be correctly detected through flat surface part  134 . 
     Effect 
     Marker  100 ′ according to the modification of Embodiment 1 has an effect similar to that of Embodiment 1. 
     Embodiment 2 
     Marker  200  according to Embodiment 2 differs from marker  100  according to Embodiment 1 only in configuration of lenticular lens part  220 . In view of this, the configurations similar to those of light emitting device  100  according to Embodiment 1 will be denoted with the same reference numerals, and the description thereof will be omitted. 
       FIGS. 5A and 5B  illustrate a configuration of marker  200  according to Embodiment 2 of the present invention.  FIG. 5A  is a plan view of marker  200  according to Embodiment 2 of the present invention, and  FIG. 5B  is a front view of marker  200 . As illustrated in  FIGS. 5A and 5B , lenticular lens part  220  according to Embodiment 2 includes first surface  223  and second surface  224 . First surface  223  includes a plurality of convex surface parts  231 , and wall part  280  including flat surface part  234 . 
     Wall part  280  is disposed on first surface  223  along a direction orthogonal to ridgeline  233  of convex surface part  231 . Specifically, wall part  280  is disposed in such a manner as to bisect convex surface part  231 . Wall part  280  includes flat surface part  234  as its top surface, and side surface  281  that connects flat surface part  234  and convex surface part  231 . Flat surface part  234  is parallel to top surface  145  of first region  241  and second region  242 . The position of wall part  280  with respect to convex surface part  231  in the first direction is not limited. In addition, the thickness of wall part  280  in the first direction is not limited as long as the function of marker  200  is not impaired. The thickness of wall part  280  is 10 to 20 μm, for example. Also, the height of wall part  280  is not limited as long as the function of marker  200  is not impaired. In the present embodiment, the height of the top surface (flat surface part  234 ) of wall part  280  is equal to the height of ridgeline  233  of convex surface part  231 . 
     Positioning part  260  is a portion corresponding to wall part  280  in the recess forming first region  241 . In marker  200  according to the present embodiment, flat wall part  280  including surface part  234  is disposed in such a manner as to bisect convex surface part  231 , and accordingly the length of the recess that serves as first region  241  is equal to the length of convex surface part  231 . Also in the present embodiment, the location information of positioning part  260  in marker  200  is correctly detected through flat surface part  234 . 
     Effect 
     Since convex surface part  231  and the recess have the same length in the first direction, marker  200  according to the present embodiment can be downsized while achieving the effect of marker  100  according to Embodiment 1. 
     Embodiment 3 
     Marker  300  according to Embodiment 3 differs from marker  100  according to Embodiment 1 only in configuration of lenticular lens part  320 . In view of this, the configurations similar to those of light emitting device  100  according to Embodiment 1 will be denoted with the same reference numerals, and the description thereof will be omitted. 
       FIGS. 6A and 6B  illustrate a configuration of marker  300  according to Embodiment 3 of the present invention.  FIG. 6A  is a plan view of marker  300  according to Embodiment 3 of the present invention, and  FIG. 6B  is a front view of marker  300 . 
     As illustrated in  FIGS. 6A and 6B , lenticular lens part  320  according to Embodiment 3 includes first surface  323  and second surface  224 . The first surface includes a plurality of convex surface parts  231 , and slit  380  including flat surface part  334 . 
     Slit  380  is disposed on first surface  323  along a direction orthogonal to ridgeline  133  of convex surface part  231 . That is, slit  380  is disposed in such a manner as to bisect convex surface part  231 . Slit  380  includes flat surface part  334  as the bottom surface. Flat surface part  334  is parallel to top surface  143  of first region  141 . The position of slit  380  with respect to convex surface part  231  in the first direction is not limited. In addition, the width of slit  380  in the first direction is not limited as long as the function of marker  300  is not impaired. The width of slit  380  is 10 to 20 μm, for example. The depth of slit  380  (the distance between flat surface part  334  and the apex of convex surface part  231 ) is not limited as long as the function of marker  300  is not impaired. 
     Positioning part  360  is a portion corresponding to wall part  280  in the recess forming first region  141 . In marker  300  according to the present embodiment, slit  380  including flat surface part  334  is disposed in such a manner as to bisect convex surface part  231 , and accordingly the length of the recess that serves as first region  141  is equal to the length of convex surface part  231 . Also in the present embodiment, the location information of positioning part  360  in marker  300  is correctly detected through flat surface part  334 . 
     Effect 
     Marker  300  according to the present embodiment has an effect similar to that of marker  200  according to Embodiment 2. 
     Embodiment 4 
     Marker  400  according to Embodiment 4 differs from marker  100  according to Embodiment 1 only in configuration of lenticular lens part  420 . In view of this, the configurations similar to those of light emitting device  100  according to Embodiment 1 will be denoted with the same reference numerals, and the description thereof will be omitted. 
       FIGS. 7A and 7B  illustrate a configuration of marker  400  according to Embodiment 4 of the present invention.  FIG. 7A  is a plan view of marker  400  according to Embodiment 4 of the present invention, and  FIG. 7B  is a front view of marker  400 . 
     As illustrated in  FIGS. 7A and 7B , lenticular lens part  420  according to Embodiment 4 includes first surface  123  and second surface  424 . Second surface  424  includes first region  141  and second region  142 . 
     Positioning part  460  is a recess that opens in a region corresponding to flat surface part  134  in second surface  124 . The shape of positioning part  460  is not limited as long as the position can be visually recognized when marker  400  is viewed from first surface  123 . In the present embodiment, positioning part  460  is formed in a shape of a box that opens at its one surface. Bottom surface  462  of positioning part  460  is parallel to top surface  143  of first region  141 . Also in the present embodiment, positioning part  460  can be correctly detected in marker  400  through flat surface part  134 . 
     Effect 
     Marker  400  according to the present embodiment has an effect similar to that of marker  100  according to Embodiment 1. 
     Embodiment 5 
     Marker  500  according to Embodiment 5 differs from marker  100  according to Embodiment 1 only in arrangement of convex surface part  131 . In view of this, the configurations similar to those of light emitting device  100  according to Embodiment 1 will be denoted with the same reference numerals, and the description thereof will be omitted. 
       FIG. 8  illustrates a configuration of marker  500  according to Embodiment 5 of the present invention. As illustrated in  FIG. 8 , in Embodiment 5, convex surface parts  131  are disposed such that convex surface parts  131  adjacent to each other are separated from each other. 
     Effect 
     With marker  500  according to the present embodiment, the position of convex surface part  131  can be highly accurately detected, and thus highly accurate marker  500  can be obtained while achieving the effect of marker  100  according to Embodiment 1. 
     Embodiment 6 
       FIGS. 9A to 9C  illustrate a configuration of marker  600  according to Embodiment 6 of the present invention.  FIG. 9A  is a plan view of marker  600  according to Embodiment 6 of the present invention,  FIG. 9B  is a front view of marker  600 , and  FIG. 9C  is a bottom view of marker  600 . 
     As illustrated in  FIGS. 9A to 9C , marker  600  includes convex lens part  620  including first surface  623  and second surface  624 , and detection object part  650 . 
     Convex lens part  620  is an optical component composed of an injection-molded article of a transparent resin. Convex lens part  620  includes first surface  623  and second surface  624 . First surface  623  includes a plurality of convex surface parts  631 , and two or more flat surface parts  634 . In addition, second surface  624  includes first region  641  and second region  642 . 
     Convex surface parts  631  have circular planar shapes and the same size. For example, the diameter of the planar shape of convex surface part  631  is 350 μm, and pitch P CL  of convex surface parts  631  is 370 μm in each of the first direction and the second direction. The term “pitch” means the distance (P CL ) between convex surface parts  631  adjacent to each other. 
     Also, the cross-sectional shape of convex surface part  631  may be a spherical surface or an aspherical surface, and preferably, the aspherical surface is a curved surface whose curvature radius increases as the distance thereof from central axis CA of convex surface part  631  increases. That is, since central axis CA of convex surface part  631  is a straight line parallel to the third direction, it is preferable that the aspherical surface be a curved surface whose curvature radius increases as the distance thereof from central axis CA of convex surface part  631  increases in the direction along the XY plane. The term “central axis CA” means a straight line extending in the third direction and passing through the center of convex surface part  631  in plan view of convex surface part  631 . 
     Flat surface part  634  is flush with the surface where convex surface part  631  is connected. The number of flat surface parts  634  is not limited as long as two or more flat surface parts  634  are provided. In the present embodiment, two flat surface parts  634  are provided. In addition, positioning parts  660  are disposed at positions corresponding to flat surface parts  634 . 
     In addition, each of convex surface part  631  and flat surface part  634  includes first region  641  disposed on the rear surface side at a position corresponding to the each of convex surface part  631  and flat surface part  634 . For example, first region  641  has a circular planar shape with a diameter of 45 μm and a depth of 10 μm. In addition, first region  641  has a rectangular cross-sectional shape in each of the first direction and the second direction. 
     The center-to-center distance (|Cn−Cn−1|) between first regions  641  adjacent to each other in the second direction is P CL +nG μm, and the center-to-center distance (|Cm−Cm−1|) between first regions  641  adjacent to each other in the second direction is P CL +mG μm. As described above, n represents the order of convex surface parts  631  in the second direction with a particular convex surface part  631  being set to 0th. The “m” represents an order of a certain convex surface part  631  with respect to 0th convex surface part  631  in the second direction. 
     Detection object part  650  is housed in each first region  641 . Detection object part  650  is formed in such a manner as to cover the bottom surface of first region  641 . In this manner, detection object part  650  is formed inside the walls of first region  641 . 
     When marker  600  is observed from convex surface part  631  side, a collective image that is composed of images of black points of detection object parts  650  projected on convex surface parts  631  is observed. The position of the collective image changes depending on the viewing angle from convex surface part  631  side. With this configuration, marker  600  is used as a turning-angle measurement device in which an image moves in the plane direction in accordance with the viewing angle. 
     It is to be noted that the planar shape of convex surface part  631  may be a rectangular shape as well as the circular shape, and may be appropriately set as long as the shape functions as a convex lens. In addition, first region  641  may be replaced by a protrusion. Also, the planar shape of first region  641  may be shapes other than the circular shape, and may be a rectangular shape, for example. 
     Effect 
     Marker  600  according to the present embodiment has an effect similar to that of marker  100  according to Embodiment 1. 
     Embodiment 7 
     Marker  700  according to Embodiment 7 differs from marker  600  according to Embodiment 6 only in second surface  124 . In view of this, the configurations similar to those of marker  600  according to Embodiment 6 will be denoted with the same reference numerals, and the description thereof will be omitted. 
       FIG. 10A  is a plan view of marker  700 ,  FIG. 10B  is a sectional view of a part of marker  700  taken along line B-B of  FIG. 10A  in which hatching is omitted,  FIG. 10C  is a bottom view of marker  700 , and  FIG. 10D  is a side view of marker  700 . 
     Second surface  124  is similar to that of Embodiment 1. Specifically, second surface  124  includes first region  141  and second region  142 . First region  141  is a slender rectangular recess extending along the Y direction in the XY plane, and is disposed across convex surface parts  631  arranged along the Y direction. In addition, second regions  124  are arranged in the X direction in such a manner as to correspond to the lines of convex surface part  631 . 
     In addition, regarding the relationship between detection object part  150  and convex surface part  631  in the X direction, the pitch of adjacent convex surface parts  631  (the pitch of convex surface parts  631  of the adjacent lines) is greater than the center-to-center distance of adjacent detection object parts  150 . In addition, positioning part  160  is disposed at a position corresponding to flat surface part  643 . 
     In marker  700 , a linear image along the Y direction is observed as a group of images projected on convex surface parts  631 . This image appears such that the image approaches the viewer as marker  700  is tilted to the viewer side with respect to the X direction. 
     Effect 
     In marker  700  according to the present embodiment, convex surface part  631  is curved not only in the X direction, but also in the Y direction, and thus the contrast of the image in the Y direction is high. 
     Embodiment 8 
     Marker  800  according to Embodiment 8 differs from marker  700  according to Embodiment 7 only in configuration of convex surface part  831 . In view of this, the configurations similar to those of marker  700  according to Embodiment 7 will be denoted with the same reference numerals, and the description thereof will be omitted. 
       FIG. 11A  is a plan view of marker  800 ,  FIG. 11B  is a sectional view of a part of marker  800  taken along line B-B of  FIG. 11A  in which hatching is omitted,  FIG. 11C  is a bottom view of marker  800 , and  FIG. 11D  is a side view of marker  800 . 
     In Embodiment 8, convex surface part  831  has a square planar shape. In addition, for example, convex surface part  831  has a spherical shape (arc shape) in the cross-section along the optical axis. 
     Effect 
     In addition to an effect similar to that of marker  700  according to Embodiment 7, with marker  800  according to the present embodiment, the image is clearly detected regardless of the intensity of the light incident on the first surface of the lenticular lens part. One possible reason for this is that, practically, the first surface of marker  800  is composed only of convex surface part  631  (curved surface) and includes no flat surface part, and thus reflection light at the first surface is less likely to be generated or is weak in comparison with marker  700  although, in the case where the intensity of the incident light is high, the intensity of the reflection light of marker  800  such as the reflection light on the first surface is also high, and the visibility of the image might be reduced. 
     Embodiment 9 
     Marker  900  according to Embodiment 9 is different from marker  700  according to Embodiment 7 only in configuration of convex surface part  931 . In view of this, the configurations similar to those of marker  700  according to Embodiment 7 will be denoted with the same reference numerals, and the description thereof will be omitted. 
       FIG. 11A  is a plan view of marker  900 ,  FIG. 11B  is a sectional view of a part of marker  900  taken along line B-B of  FIG. 11A , in which hatching is omitted,  FIG. 11C  is a bottom view of marker  900 , and  FIG. 11D  is a side view of marker  900 . 
     In Embodiment 9, convex surface part  931  has a regular-hexagon planar shape. In addition, for example, convex surface part  931  has a spherical shape (arc shape) in the cross-section along the optical axis. Regarding the line of convex surface parts  931  in the Y direction, convex surface parts  931  are arranged along the Y direction such that their opposed sides are in contact with each other. In addition, the lines of convex surface parts  931  are arranged in the X direction such that of each connecting part of convex surface parts  73  of one line is in contact with a corner of the hexagon of each convex surface part  931  of another line. In this manner, in marker  900 , convex surface parts  931  are fully closely arranged in a collective manner over the entirety of the first surface. 
     Effect 
     Marker  900  according to the present embodiment has an effect similar to that of marker  800  according to Embodiment 8. 
     While the detection object part is made of a solidified coating material in the embodiments, the detection object part may be made of a colored seal. 
     While the detection object part is a coating film disposed in the first region in the embodiments, the detection object part may be disposed in both of the first region and the second region. In this case, the first regions and the second regions may be coating films and/or seals of different colors. Further, the detection object part may be a reflection surface composed of an irregularity of pyramidal minute prism and a metal-vapor deposited film and the like which is formed in the first region and/or the second region. 
     This application is entitled to and claims the benefit of Japanese Patent Application No. 2015-249997 filed on Dec. 22, 2015, the disclosure each of which including the specification, drawings and abstract is incorporated herein by reference in its entirety. 
     INDUSTRIAL APPLICABILITY 
     The marker according to the embodiments of the present invention is useful as a measuring device for recognizing the position and/or the orientation of an object and the like. In addition, the present invention is expected to contribute not only to development of the technical field of the measuring device, but also to development of various technical fields where highly accurate application of a pattern to the convex lens is desired. 
     REFERENCE SIGNS LIST 
     
         
           100 ,  100 ′,  200 ,  300 ,  400 ,  500 ,  600 ,  700 ,  800 ,  900  Marker 
           120 ,  120 ′,  220 ,  320 ,  420  Lenticular lens part 
           123 ,  223 ,  323 ,  623  First surface 
           124 ,  124 ′,  224 ,  424 ,  624  Second surface 
           131 ,  231 ,  631 ,  831 ,  931  Convex surface part 
           132  Side surface part 
           133 ,  233  Ridgeline 
           134 ,  234 ,  334 ,  634  Flat surface part 
           141 ,  141 ′,  241 ,  641  First region 
           142 ,  142 ′,  242 ,  642  Second region 
           143  Top surface 
           143 ′ Top surface 
           144  First inner surface 
           144 ′ First outer surface 
           145  Second inner surface 
           145 ′ Second outer surface 
           150 ,  150 ′,  650  Detection object part 
           160 ,  160 ′,  260 ,  360 ,  460 ,  660  Positioning part 
           462  Bottom surface 
           170  Metal mold 
           171  Upper mold 
           172  Lower mold 
           173  Recessed surface part 
           174  Flat surface 
           175  Linear projection 
           280  Wall part 
           281  Side surface 
           380  Slit 
           620  Convex lens part