JP2016071663A - Information communication system and information reading method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an information communication system and an information reading method with which the size of a tag can be reduced and tag information can be read from a distant position.SOLUTION: A camera 200 includes: a light emitting part (infrared light emitting part 210) that emits infrared light; a light receiving part (infrared light receiving part 220) that receives, out of the infrared light emitted from the light emitting part (infrared light emitting part 210), infrared light that has passed through liquid crystal 120 of a tag 100 and reflected on a retroreflective material 110 of the tag 100 so as to include information on the tag 100; and a decryption part that decrypts the information on the tag 100 included in the infrared light received by the light receiving part (infrared light receiving part 220).SELECTED DRAWING: Figure 5

Description

  The present invention relates to an information communication system and an information reading method.

  The barcode printed on the product package is a familiar example of adding information to an object. If a two-dimensional code such as a QR code (registered trademark) or a code using a plurality of colors is used for a one-dimensional code such as a barcode, more information can be transmitted. These codes (tags) are generally called visual codes or visual tags. The code is photographed with a camera, and the information embedded in the code is decoded from the photographed image. Since it is possible to specify where the code is in the photographed image, it is also widely used for applications such as augmented reality (AR).

  Wireless tags such as RFID (Radio Frequency IDentification) tags, Bluetooth (registered trademark) tags, and WiFi (registered trademark) tags are also widely used. By using a wireless tag, for example, even when the wireless tag is out of the field of view, the tag information can be decoded by wireless communication.

  Some tags use optical communication. By using optical communication, the reading distance can be increased even with a small tag. The light may be emitted on the tag side or on the reader side.

Japanese Patent Publication No. 2014-96087 Japanese Patent Publication No. 2003-122896 Japanese Patent Publication No. 2011-235997 Japanese Patent Publication No. 2007-266974

  It is desirable to reduce the size of the tag so that it can be attached to various objects and can be melted into the environment without being noticeable. It is also desirable that tag information can be read from a long distance.

  In a visual tag, if the tag is downsized, it becomes difficult to read tag information from a long distance. In a tag using optical communication, for example, a light emitting device or the like must be mounted on the tag, so that the tag may be enlarged accordingly. Even with a wireless tag, for example, since a wireless device or the like must be mounted on the tag, the tag may be increased in size accordingly.

  The present invention has been made in view of the above problems, and provides an information communication system and an information reading method capable of downsizing a tag and reading tag information from a long distance. Objective.

  Here, the present invention focuses on a camera (for example, a depth camera) that uses infrared light (infrared light), which has been practically used in recent years. By using infrared light, the distance to the object can be measured (measured). As a distance measurement method, for example, the Structured Light method, the Time of Flight method, or the like is known. A camera capable of measuring the distance to an object in this way will be mounted on a mobile communication terminal such as a smartphone in the future in accordance with downsizing of an infrared light sensor (for example, a depth sensor). There is a possibility that it will be available more closely.

  An information communication system according to an aspect of the present invention is an information communication system including a tag and a camera for reading information on the tag, wherein the tag has a reflective surface that reflects infrared light. Covering the reflective surface of the retroreflective material, switching the state and affecting the infrared light, and the liquid crystal so that the infrared light reflected by the retroreflective material contains the tag information A control unit that switches the state, and the camera transmits the tag liquid crystal so as to include the tag information out of the infrared light emitted from the light emitting unit and the infrared light emitted from the light emitting unit, and A light receiving unit that receives infrared light reflected by the retroreflecting material, and a decoding unit that decodes information of a tag included in the infrared light received by the light receiving unit.

  An information reading method according to an aspect of the present invention is an information reading method executed by a tag and a camera for reading information on the tag, wherein the camera emits infrared light, and the tag is infrared. The infrared light emitted by the step of emitting light changes the state of the liquid crystal so as to include the tag information and is reflected by the retroreflecting material, and the infrared light reflected by the camera is reflected by the step of reflecting. Receiving, and deciphering tag information contained in the infrared light received by the camera receiving the infrared light.

  According to the information communication system or the information reading method described above, when infrared light emitted from the camera is irradiated to the tag, the infrared light is transmitted through the liquid crystal and retroreflected so as to include the tag information. Reflected by the material. The camera receives the reflected infrared light and decodes the tag information. Thereby, the camera can acquire tag information. Here, in the tag, tag information is imparted to infrared light by using a liquid crystal and a retroreflecting material, so that no infrared light emitting device or the like is required on the tag side. Therefore, the tag can be reduced in size. Furthermore, even if the tag is downsized, tag information embedded in the time direction is acquired, so that information on the tag embedded in the spatial direction such as a barcode is decoded from the camera image, for example. The tag information can be read from a long distance.

  The camera may be a depth camera that can measure the distance from the camera to the tag. When a depth camera is used, in addition to tag information, the distance to the tag can be acquired. For this reason, more information can be used.

  In addition, the decoding unit is configured so that the intensity of infrared light received by the light receiving unit when the light emitting unit emits infrared light and the intensity of infrared light received by the light receiving unit when the light emitting unit does not emit infrared light. The tag information may be decrypted based on the difference. Thereby, the noise by ambient light can be reduced and tag information can be read.

  Further, the retroreflective material may include a plurality of retroreflective materials having different colors. Thereby, since the retroreflective material can have visible information separately from the tag information included in the infrared light, more information can be acquired by imaging the tag with the camera. .

  The tag may further include an optical filter that covers a surface of the liquid crystal opposite to the retroreflecting material, absorbs or reflects visible light, and transmits infrared light. Thereby, it is possible to make the tag inconspicuous by making the tag invisible.

  The tag may further include a power generation element that generates power upon receiving infrared light. Thereby, even if the tag does not have a battery or the like, it is possible to obtain electric power necessary for switching the liquid crystal state.

  The retroreflecting material may have a convex shape that is convex toward the side where the liquid crystal is disposed or a concave shape that is concave. Thereby, the dependence of the area of the retroreflecting material when viewing the tag from the camera on the angle can be reduced. Therefore, the camera can read the tag information by irradiating the retroreflecting material having the same area as that in the front surface with infrared light, even if it is not in a position facing the tag (for example, the front surface of the tag).

  The camera further includes a position information acquisition unit that acquires tag position information from a server that stores tag position information based on a decoding result of the decoding unit, and a plurality of tags within the angle of view of the camera. Based on the imaging data and at least one of the distance data between the camera and each of the plurality of tags and the position information acquired by the position information acquisition unit (measurement unit (first Measuring unit). Thereby, the position of the camera can be measured.

  The camera further includes a position information acquisition unit that acquires tag position information from a server that stores tag position information based on the decoding result of the decoding unit, and the camera pitch, roll, and yaw. At least one of a posture detection unit that is detected as a parameter representing the posture, a parameter detected by the posture detection unit, imaging data of the tag within the angle of view of the camera, and distance data between the camera and the tag, and a position A measurement unit (second measurement unit) that measures the position of the camera based on the position information acquired by the information acquisition unit may be included. Accordingly, if position information of one or more tags and imaging data and / or distance data are obtained, the camera posture parameter is measured, and the camera position is further measured (estimated) using the posture parameter. can do.

  The decoding unit may decode the tag information based on the temporal change in the reflection intensity of the infrared light reflected by the retroreflecting material of the tag. Thereby, for example, the tag can be detected (discovered) based on whether or not the reflection intensity changes with time.

  According to the present invention, the tag can be reduced in size, and tag information can be read from a long distance.

It is a figure which shows schematic structure of the information communication system which concerns on 1st Embodiment. It is a figure which shows an example of a structure of a tag. It is a figure which shows the functional block of a control part. It is a figure which shows the functional block of a camera. It is a figure for demonstrating operation | movement of a tag. It is a figure which shows an example of the time change of the reflection intensity in a tag. It is a flowchart which shows an example of the process performed in an information communication system. It is a front view which shows the modification of a tag. It is a figure which shows another modification of a tag. It is a figure which shows the structure of the tag which concerns on another modification. It is a figure which shows the structure of the tag which concerns on another modification. It is a figure for demonstrating an example of the method of transmitting information from a camera to a tag. It is a figure which shows schematic structure of the information communication system which concerns on 2nd Embodiment. It is a figure which shows the functional block of a camera. It is a figure which shows an example of the image containing a some tag imaged with a camera. It is a flowchart which shows an example of the process performed in an information communication system. It is a figure which shows schematic structure of the information communication system which concerns on 3rd Embodiment. It is a figure which shows an example of the image containing a tag imaged with two cameras. It is a figure which shows an example of the image containing a tag, a target object, etc. imaged with two cameras.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant descriptions are omitted.

[First Embodiment]
FIG. 1 is a diagram showing a schematic configuration of the information communication system according to the first embodiment. As shown in FIG. 1, the information communication system 1 includes a tag 100 and a camera 200.

  The camera 200 includes an infrared light emitting unit 210 and an infrared light receiving unit 220. The camera 200 may further include a visible light receiving unit 230. Other elements included in the camera 200 will be described later with reference to FIG.

  For example, a depth camera can be employed as the camera 200. In this case, the camera 200 can measure the distance from the camera 200 to the object (tag 100) according to the principle described later.

  The infrared light emitting unit 210 emits infrared light (infrared rays). For example, the infrared light emitting unit 210 includes a light emitting element such as a light emitting diode.

  The infrared light receiving unit 220 receives infrared light. In particular, the infrared light receiving unit 220 is assumed to receive infrared light (reflected light) reflected by the tag 100 among the infrared light emitted from the infrared light emitting unit 210. The infrared light receiving unit 220 includes a light receiving element such as a photodiode, for example.

  The visible light receiving unit 230 receives visible light. When the camera 200 includes the visible light receiving unit 230, the camera 200 can capture an image of the tag 100. The visible light receiving unit 230 is configured to include an imaging device using a semiconductor sensor, for example.

  In the information communication system 1, the camera 200 irradiates the tag 100 with infrared light emitted from the infrared light emitting unit 210. The tag 100 reflects infrared light so as to include information (tag information) of the tag 100 (details will be described later). The camera 200 receives the infrared light reflected by the tag 100 by the infrared light receiving unit 220 and acquires the information of the tag 100 by decoding the received infrared light. When the camera 200 is a depth camera, the camera 200 further measures the distance from the camera 200 to the tag 100. Therefore, the camera 200 can acquire two pieces of information, namely the tag information and the distance to the tag 100.

  FIG. 2 is a diagram illustrating an example of the configuration of the tag 100. 2A is an exploded perspective view of the tag 100, and FIG. 2B is a view of the tag 100 as viewed from the front (the reflective surface 110a side). As shown in FIG. 2, the tag 100 includes a retroreflecting material 110, a liquid crystal 120, and a control unit 130. In FIG. 2, infrared light irradiated to the tag 100 from the camera 200 (FIG. 1) is illustrated as infrared light IR1.

  The retroreflective material 110 has a reflective surface 110a. The retroreflecting material 110 reflects the light incident on the reflecting surface 110a toward the incident direction. Here, although light is classified according to a wavelength range or the like, in the embodiment, the reflecting surface 110a may reflect at least the infrared light IR1. Of course, the reflective surface 110a may reflect light other than infrared light. The configuration of the retroreflective material 110 is not particularly limited, and for example, a retroreflective material of a type utilizing refraction and reflection by glass beads can be employed. In the example shown in FIG. 2, the retroreflecting material 110 has a sheet shape (or plate shape), but the shape of the retroreflecting material 110 is not particularly limited.

  The liquid crystal 120 covers the reflective surface 110 a of the retroreflecting material 110. The liquid crystal 120 is switched between an on state and an off state. Thereby, infrared light can be affected. For example, the liquid crystal 120 can include a liquid crystal that can change the haze value. An example of such a liquid crystal is a polymer dispersed liquid crystal (PDLC). In the case of using PDLC, the liquid crystal 120 can transmit light in the on state while diffusing light in the off state. The light transmittance in PDLC is higher than the light transmittance in a general liquid crystal. When the transmittance is high, the tag 100 reflects a large amount of light toward the liquid crystal 120, so that the intensity (light quantity) of light received by the camera 200 (FIG. 1) also increases. As a result, the distance that the camera 200 can read the information on the tag 100 can be extended. For example, tag information can be read even if the distance from the camera 200 to the tag 100 is several meters or more. In addition, when a general liquid crystal is used as the liquid crystal 120, the color of the tag 100 changes between when the liquid crystal 120 is in an on state and when it is in an off state. That is, the color of the retroreflecting material 110 appears when the liquid crystal 120 is on, and black appears when the liquid crystal 120 is off. For this reason, the tag 100 becomes conspicuous and cannot be dissolved into the environment.

  In the example shown in FIG. 2, the liquid crystal 120 has a sheet shape, but the shape of the liquid crystal 120 is not particularly limited. For example, when the liquid crystal 120 has a sheet shape, the liquid crystal 120 includes a liquid crystal molecule and a pair of sheets (not shown) sandwiching the liquid crystal molecule. For example, a sheet made of glass or plastic can be used as the sheet. The sheet may be a foldable flexible sheet.

  The control unit 130 switches the liquid crystal 120 on and off. The on / off switching can be performed by controlling the voltage applied to the liquid crystal 120, for example. The control unit 130 switches the on / off state of the liquid crystal 120 so that the infrared light reflected by the reflective surface 110a of the retroreflecting material 110 includes information on the tag 100 (tag information). For example, the tag information can be included in the reflected infrared light by using the digital information represented by the time change of the intensity of the reflected infrared light as the tag information.

  Here, with reference to FIG. 3, the functional block of the control part 130 is demonstrated. As shown in FIG. 3, the control unit 130 includes a power supply unit 131 and a voltage generation unit 132.

  The power supply unit 131 is a power source of the control unit 130. The control unit 130 operates with the power of the power supply unit 131. The power supply unit 131 may be configured to receive power supplied from outside the control unit 130 (for example, a power generation element 140 in FIG. 8 described later). For example, the control unit 130 operates when the voltage of the power supply unit 131 is equal to or higher than a predetermined value. Note that the power supply unit 131 can also be configured to receive power from a battery (not shown) or the like inside the control unit 130.

  The voltage generator 132 generates a voltage to be applied to the liquid crystal 120 (FIG. 2). The voltage generation unit 132 operates by receiving power from the power supply unit 131.

  The function of the control unit 130 is physically a circuit including an active element such as a semiconductor element and a passive element such as a resistor, a coil and a capacitor, a CPU (Central Processing Unit), a RAM (Random Access Memory), and a ROM ( This is realized by an IC (Integral Circuit) including Read Only Memory).

  Returning to FIG. 2 again, the shape of the tag 100 is not particularly limited. For example, the retroreflective material 110 having a sheet shape and the liquid crystal 120 may be overlapped. In the example shown in FIG. 2B, the area of the liquid crystal 120 is larger than the area of the retroreflecting material 110. In this case, the control unit 130 can be disposed in a portion where the retroreflecting material 110 and the liquid crystal 120 do not overlap. In this way, since the area of the tag 100 does not become larger than the area of the liquid crystal 120, an increase in the area of the tag 100 can be suppressed. Further, since the tag 100 has a sheet shape, the tag 100 is thinned. Therefore, the tag 100 can be reduced in size. Note that the control unit 130 may be disposed on the back surface of the retroreflecting material 110. Also by this, it can suppress that the area of the tag 100 becomes large.

  FIG. 4 is a diagram illustrating functional blocks of the camera 200. As shown in FIG. 4, the camera 200 includes an infrared light emitting unit 210, an infrared light receiving unit 220, a visible light receiving unit 230, a display unit 240, a decoding unit 250, and an operation unit 260. .

  The infrared light receiving unit 220 has been described above. In more detail, the infrared light receiving unit 220 includes the infrared light emitted from the infrared light emitting unit 210 of the tag 100 (FIG. 2). It is a portion that receives infrared light that is transmitted through the liquid crystal 120 of the tag 100 and reflected by the retroreflecting material 110 of the tag 100 so as to include information.

  The display unit 240 is a part that displays an image captured by the camera 200. The image is created based on the light received by the visible light receiving unit 230, for example. The display unit 240 can also display various information necessary for the user of the camera 200 to operate the camera 200.

  The decoding unit 250 is a part that decodes information of the tag 100 (FIG. 2) included in the infrared light received by the infrared light receiving unit 220. Decoding is performed, for example, by reading digital information from a temporal change in the intensity of infrared light.

  FIG. 5 is a diagram for explaining the operation of the tag 100. FIG. 5A is a diagram illustrating the liquid crystal 120 in an on state. FIG. 5B is a diagram illustrating the liquid crystal 120 in the off state.

  As shown in FIG. 5A, when the liquid crystal 120 is in the on state, the infrared light IR1 from the camera 200 is transmitted through the liquid crystal 120. In this case, the infrared light IR1 is reflected by the reflecting surface 110a of the retroreflecting material 110, passes through the liquid crystal 120 again, and returns to the camera 200. In FIG. 5A, the reflected infrared light is illustrated as infrared light IR2.

  On the other hand, as shown in FIG. 5B, when the liquid crystal 120 is in the OFF state, the infrared light IR1 from the camera 20 does not pass through the liquid crystal 120. For example, when the liquid crystal 120 is PDLC, the infrared light IR1 diffuses. The diffused light is reflected by the retroreflecting material 110 and again diffused by the liquid crystal 120. In FIG. 5B, the diffused infrared light is illustrated as infrared light IR3. Since the infrared light IR3 travels in various directions, little infrared light returns to the camera 200. Note that, when the liquid crystal 120 is a general liquid crystal, the infrared light IR1 is blocked (absorbed), but in this case as well, the infrared light returning to the camera 200 is small.

  As described above, the amount of infrared light (reflected light) returning to the camera 200 is larger when the liquid crystal 120 is in the on state and when it is in the off state. That is, when the liquid crystal 120 is on, the reflection intensity at the tag 100 increases, and when the liquid crystal 120 is off, the reflection intensity at the tag 100 decreases. Therefore, for example, by changing the reflection intensity by switching the liquid crystal 120 on and off at a predetermined timing, the intensity (light quantity) of the reflected light received by the infrared light receiving unit 220 of the camera 200 can be changed with time. it can. The camera 200 can read the tag information by associating the temporal change in the intensity of the reflected light based on the predetermined timing with the information (tag information) of the tag 100. That is, the decoding unit 250 of the camera 200 can decode the tag information based on the time series data of the intensity of the reflected light. The tag information can be transmitted from the tag 100 to the camera 200 by various methods by changing the setting of the temporal change in the intensity of the reflected light. Although the transmission method is not particularly limited, for example, a Manchester code can be used. Moreover, the decoding part 250 can also detect the presence or absence of the tag 100 by detecting the presence or absence of the time change of the intensity of reflected light.

  Thus, the function of the camera 200 for decoding the tag information based on the time-series data of the intensity of the reflected light is different from that of the conventional depth camera. That is, the conventional depth camera uses infrared light to measure the distance, but the intensity of the reflected light reflected and returned from the object is not used to measure the distance to the object. This is because the intensity of the reflected light is affected not only by the distance but also by the reflectance inherent to each object. In some cases, the intensity of reflected light is measured, but it is only acquired as an index representing the reliability of the result (measurement result) when measuring the distance. On the other hand, in the first embodiment, the camera 200 reads the tag information from the temporal change in the intensity of the reflected light. In this way, when the camera 200 is a depth camera, the camera 200 can measure the distance from the camera 200 to the tag 100 and read the tag information in parallel.

  Here, the infrared light receiving unit 220 of the camera 200 can also receive ambient light other than the reflected light from the tag 100. If the received ambient light appears as noise, the tag information cannot be read accurately. Therefore, the decoding unit 250 cooperates with the infrared light emitting unit 210 and the infrared light receiving unit 220 to receive the infrared light receiving unit 220 when the infrared light emitting unit 210 emits infrared light. Tag information can also be decoded based on the difference between the intensity of infrared light and the intensity of infrared light received by the infrared light receiving unit 220 when the infrared light emitting unit 210 does not emit infrared light. . As a result, it is possible to cancel the influence of the intensity of infrared light (that is, ambient light as noise) received by the infrared light receiving unit 220 when the infrared light emitting unit 210 does not emit infrared light. The influence of noise can be reduced, and tag information can be read accurately.

  FIG. 6 is a diagram illustrating an example of a temporal change in reflection intensity in the tag 100. In the graph shown in FIG. 6, the horizontal axis indicates time, and the vertical axis indicates the reflection intensity at the tag 100.

  In the graph shown in FIG. 6, the reflection intensity takes two values, η1 and η2. η1 is the reflection intensity when the liquid crystal 120 (FIG. 2 or the like) is in the on state, and η2 is the reflection intensity when the liquid crystal 120 is in the off state. In the example shown in FIG. 6, the change in reflection intensity at times t10 to t20, the change in reflection intensity at times t20 to t30, and the change in reflection intensity at times t30 to t40 correspond to 0, 1, and 1 of the digital signal, respectively. doing. In the example shown in FIG. 6, Manchester code is used, and the reflection intensity changes from η1 (time t10 to t15) to η2 (time t15 to t20) between times t10 and t20. Also, the reflection intensity changes from η2 (time t20 to t25) to η1 (time t25 to t30) from time t20 to t30, and similarly, the reflection intensity changes from η2 (time t30 to t35) to η1 (time t30 to t40). Time t35 to t40). In this way, the tag information can be transmitted from the tag 100 to the camera 200 by converting the digital information (0 or 1) into the signal changing direction (η1 to η2 or η2 to η1).

  FIG. 7 is a flowchart showing an example of processing executed in the information communication system 1 (FIG. 1). The process of this flowchart is started in response to the execution of an application for reading information on the tag 100 in the camera 200, for example.

  First, the infrared light emitting unit 210 of the camera 200 emits infrared light (step S101).

  Then, the tag 100 receives infrared light from the camera 200 (step S102).

  Next, the tag 100 reflects infrared light while switching the liquid crystal between an on state and an off state (step S103). Specifically, the control unit 130 controls the voltage applied to the liquid crystal 120 to switch the liquid crystal 120 between an on state and an off state. Thereby, the infrared light is reflected by the retroreflecting material 110 so as to include the information of the tag 100.

  Then, the infrared light receiving unit 220 of the camera 200 receives the reflected infrared light (step S104).

  And the decoding part 250 of the camera 200 decodes the tag information contained in infrared light (step S105).

  Next, effects of the information communication system 1 according to the first embodiment will be described. According to the information communication system 1, when infrared light emitted from the camera 200 is irradiated to the tag 100, the infrared light is transmitted through the liquid crystal 120 and retroreflected so as to include information on the tag 100. Reflected by the material 110 (steps SS101 to S103). The camera 200 receives the reflected infrared light and decodes the tag information (steps S104 and S105). Thereby, the camera 200 can acquire tag information. Here, in the tag 100, the tag information is imparted to the infrared light by using the liquid crystal 120 and the retroreflecting material 110, so that no infrared light emitting device or the like is required on the tag 100 side. Therefore, the tag 100 can be reduced in size. Furthermore, since the tag information embedded in the time direction is acquired, the distance at which the tag information can be read is made longer than when the information of the tag embedded in the spatial direction such as a barcode is decoded from the camera image. can do.

  FIG. 8 is a front view showing a modification of the tag. As shown in FIG. 8, the tag 100 </ b> A includes a retroreflecting material 110 </ b> A, a liquid crystal 120, and a control unit 130. Furthermore, the tag 100A may include a power generation element 140.

  The retroreflective material 110A includes a plurality of retroreflective materials having different colors. In the example shown in FIG. 8, the retroreflective material 110 includes two types of retroreflectors, a retroreflective material 111 (first retroreflective material) and a retroreflective material 112 (second retroreflective material). Includes reflective material. However, the number of retroreflective materials included in the retroreflective material 110 may be larger than two.

  The retroreflecting material 112 has a color and shape that can be visually recognized by a person such as a user of the camera 200 (FIG. 1). In the case where the liquid crystal 120 is a PDLC, the user or the like is recursively arranged on the back side of the liquid crystal 120 (the side opposite to the front surface of the tag 100A) regardless of whether the liquid crystal 120 is in the on state or the off state. The reflective material 112 can be visually recognized. Therefore, information can be provided to the user by devising the shape of the retroreflecting material 112. In the example shown in FIG. 8, the retroreflective material 112 is formed to represent a character string “EXIT”. That is, not only the on state and the off state of the liquid crystal 120 but the character information “EXIT” can always be provided from the tag 100 to the user. When the liquid crystal 120 is not a PDLC but a normal liquid crystal, the user can visually recognize the characters “EXIT” only when the liquid crystal is in an on state.

  What is important here is that even if the text information “EXIT” is provided to the user by the retroreflecting material 112 in this way, it does not affect the performance of the tag 100A. That is, for example, if the characters “EXIT” are represented by ink instead of the retroreflecting material 112, the character information of “EXIT” can be provided to the user, but the area of the reflective surface of the retroreflecting material is the ink. It will be smaller by As a result, the amount of infrared light reflected by the tag 100A and returning to the camera 200 (FIG. 1) also decreases, so that, for example, the distance at which information on the tag 100A can be read is shortened. On the other hand, as shown in FIG. 8, the character string “EXIT” is represented by the two types of retroreflective material 111 and the retroreflective material 112, which are different in color and the like, but are both retroreflective materials. Then, since the size (area) of the reflection surface is maintained, the reflection performance (reflection intensity) of the tag 100A is not impaired. Therefore, the tag information of the tag 100A can be read even from a distance.

  As described above, the tag 100A may include the power generation element 140. The power generation element 140 generates electric power for switching the liquid crystal 120 between an on state and an off state. As the power generation element 140, for example, a solar cell can be used. In the example illustrated in FIG. 8, the power generation element 140 includes a plurality of solar cells 140a to 140f.

  Since the tag 100A does not include, for example, an infrared light emitting device, the tag 100A is not only reduced in size, but also reduces power consumption. Specifically, it is only necessary to have power for driving the liquid crystal 120 (power for operating the control unit 130), and such power is considerably smaller than the power consumption of the infrared light emitting device. Therefore, even a small solar cell functions sufficiently as the power generation element 140 of the tag 100A. Therefore, the size reduction of the tag 100A can be maintained.

  FIG. 9 is a diagram illustrating another modification of the tag. FIG. 9A is an exploded perspective view of the tag 100B, and FIG. 9B is a view of the tag 100B as viewed from the front. As shown in FIG. 9, the tag 100 </ b> B includes a retroreflecting material 110, a liquid crystal 120, an optical filter 150, and ink 160.

  The optical filter 150 is disposed so as to cover the upper surface of the liquid crystal 120. The upper surface of the liquid crystal 120 is a surface of the liquid crystal 120 on the side opposite to the retroreflecting material 110, and is a surface on the front side of the tag 100A. The front surface of the tag 100A is a surface on the side irradiated with the infrared light IR1. The optical filter 150 transmits infrared light while absorbing or reflecting visible light. In the example shown in FIG. 9, the optical filter 150 is an optical film having a sheet shape (or plate shape), but the shape of the optical filter 150 is not particularly limited. The optical filter 150 can also be configured by combining a plurality of sheets, for example, a sheet that transmits infrared light and a sheet that absorbs (or reflects) visible light.

  The ink 160 is applied to a part of the upper surface of the optical filter 150. The upper surface of the optical filter 150 is a surface of the optical filter 150 on the front side of the tag 100A. In the example illustrated in FIG. 9, the characters “EXIT” are represented by the ink 160. Accordingly, the user or the like can visually recognize the character information “EXIT”.

  According to the tag 100B, since the optical filter 150 absorbs visible light, when the tag 100B is viewed from the front, among the components of the tag 100B, the optical filter 150 is disposed on the rear side (the side opposite to the front). The components that are present are not visible to the user or the like. In the example shown in FIG. 9B, the retroreflecting material 110, the liquid crystal 120, and a part of the control unit 130 are not visually recognized. Thus, by hiding many components from the user or the like, the tag 100B can be made inconspicuous. On the other hand, the user or the like can visually recognize the ink 160 disposed on the front side of the optical filter 150. Therefore, the character information “EXIT” can be provided to the user or the like at all times (regardless of whether the liquid crystal 120 is on or off).

  Further, instead of the ink 160, an optical filter (second optical filter) (not shown) different from the optical filter 150 may be used. Another optical filter is configured to have a different absorption spectrum of visible light from the optical filter 150. Another optical filter may be configured in the same manner as the optical filter 150 in that infrared light is transmitted. Since the optical filter 150 and another optical filter having a different absorption spectrum of visible light appear to have different colors when viewed from the user or the like, the user or the like may be, for example, “EXIT formed by another optical filter. "Can be read. In addition, since the ink 160 is not used, it is possible to prevent the reading area of the tag 100B from being reduced due to a reduction in the area of the reflection surface.

  FIG. 10 is a diagram illustrating a configuration of a tag according to another modification. FIG. 10A is a view of the tag 100C as viewed from above. FIG. 10B is a view of the tag 100C as viewed from the back.

  As shown in FIG. 10, the tag 100C includes a retroreflecting material 110C and a liquid crystal 120C. In FIG. 10, illustration of other elements (such as the control unit 130 in FIG. 2) included in the tag 100C is omitted.

  As shown in FIG. 10A, the retroreflective material 110C has a convex shape that is convex toward the side where the liquid crystal 120C is disposed (the side irradiated with the infrared light IR1). For this reason, the retroreflective material 110C is configured to have a non-flat reflective surface. In the example illustrated in FIG. 10, the retroreflecting material 110 </ b> C is configured to have three reflecting surfaces 110 </ b> C, 110 </ b> Cb, and 110 </ b> Cc. However, the number of reflecting surfaces is not particularly limited. The surface directions of the reflecting surfaces 110Cb and 110Cc are different from the surface direction of the reflecting surface 110Ca. The reflective surface 110Ca reflects the infrared light IR1 applied to the front surface of the tag 100C in the front direction. Similarly, the reflecting surface 110Cb and the reflecting surface 110Cc also reflect the infrared light IR1 irradiated on the front surface of the tag 100C in the front direction. Thereby, the dependence of the area of the retroreflecting material on the angle when the tag 100C is viewed from the camera can be reduced while maintaining the reflection characteristics of the tag 100C. By appropriately designing the reflective surfaces 110Ca, 110Cb, and 110Cc, the area of the retroreflecting material can be kept substantially constant even when the tag 100C is viewed from a camera at different angles.

  The liquid crystal 120C has a convex shape that is convex toward the side irradiated with the infrared light IR1 in accordance with the shape of the retroreflecting material 110C. Such a liquid crystal 120C can be configured by combining, for example, three plate-like (sheet-like) liquid crystals that respectively fit the three reflecting surfaces 110Ca, 110Cb, and 110Cc of the retroreflecting material 110C.

  According to the tag 100C, even when the tag 100C is viewed from the camera at different angles, the area of the tag 100C can be kept substantially constant. For this reason, even if the camera 200 (FIG. 1) is not located at a position facing the tag 100C (for example, the front face of the tag 100C), an area for irradiating infrared light to the cameras 200 to 100C is secured, and infrared light is irradiated. It becomes easy. That is, the camera 200 can read the tag information even if it is not in front of the tag 100C, as in the case of being in front. This effect is similarly obtained even when the retroreflective member 110C of the tag 100C has a concave shape that is concave toward the side where the liquid crystal 120C is disposed. The same applies to the retroreflecting material 110D of the tag 100D described later.

  On the other hand, the configuration shown in FIG. 11 may be employed as a tag having the same function as the tag 100C.

  As shown in FIG. 11, the tag 100D includes a retroreflecting material 110D and a liquid crystal 120D. Also in FIG. 11, illustration of other elements (such as the control unit 130 in FIG. 2) is omitted.

  As shown in FIG. 11A, the retroreflective material 110D is also directed toward the side where the liquid crystal 120D is disposed (the side irradiated with the infrared light IR1), like the retroreflective material 110C (FIG. 10). And has a convex shape. Here, the retroreflecting material 110 </ b> D is configured to have one reflecting surface 110 </ b> Da that is not flat. The reflective surface 110Da can be formed, for example, by curving a retroreflecting material. The reflective surface 110Da reflects the infrared light IR1 irradiated on the front surface of the tag 100D in the front direction.

  The liquid crystal 120D has a shape that matches the shape of the retroreflecting material 110D.

  Similarly to the tag 100C (FIG. 10), the tag 100D can keep the area of the retroreflecting material almost constant when the tag 100D is viewed from the camera at different angles. Moreover, since the tag 100D can be configured only by bending the retroreflecting material and the liquid crystal, for example, it can be easily manufactured.

  The method for reading tag information from the tag with the camera has been described above. On the other hand, if information can be transmitted from the camera to the tag, information can be exchanged between the tag and the camera. Specifically, for example, the tag information is switched on the tag side when the user operates the camera, the tag operates to reduce power consumption only when the camera is imaging the tag, and the tag setting is changed. The use of such is considered.

  Therefore, a method for enabling information transmission from the camera to the tag by applying the tag 100A having the configuration including the power generation element 140 as described above with reference to FIG. 8 will be described.

[Application example]
FIG. 12 is a diagram for explaining an example of a method for transmitting information from a camera to a tag. FIG. 12A is a diagram illustrating an example of the configuration of the power generation element 140, the control unit 130, and the like in the tag 100A. FIG. 12B is a diagram for explaining the time change of the voltage of the power generation element 140 and the voltage for operating (driving) the control unit 130.

  As shown in FIG. 12A, the control unit 130 receives power generated by the power generation element 140. As described above with reference to FIG. 3, the control unit 130 included in the tag operates as the liquid crystal 120 (FIG. 2) is turned on when the voltage generation unit 132 operates by receiving power from the power supply unit 131. And toggle off state. For example, the control unit 130 operates when the voltage of the power supply unit 131 is equal to or higher than a predetermined value. In the configuration illustrated in FIG. 12A, a voltage corresponding to the voltage V <b> 1 generated by the power generation element 140 is applied to the power supply unit 131 of the control unit 130. The control unit 130 operates when the voltage applied to the power supply unit 131 is equal to or higher than a predetermined value.

  In this application example, the control unit 130 detects the voltage V <b> 1 of the power generation element 140. For example, as shown in FIG. 12B, a voltage sensor (voltage measurement unit) 133 for monitoring the voltage V1 of the power generation element 140 is provided. By acquiring the monitoring result (detection result) of the voltage sensor 133, the control unit 130 can detect the voltage V1 of the power generation element 140.

  Here, as described above, the power generation element 140 is, for example, a solar battery. The amount of light received by the solar cell varies depending on the environment and is not constant, and the voltage V1 of the power generation element 140 is not stable. Therefore, in order to supply a stable voltage (electric power) to the control unit 130, a circuit including the diode 141 and the capacitor 142 is connected between the power generation element 140 and the control unit 130. Specifically, the diode 141 is connected between the power generation element 140 and the control unit 130 so that a current flows from the power generation element 140 toward the control unit 130. The capacitor 142 is connected in parallel to the control unit 130 so that a voltage can be applied to the control unit 130. By doing so, it is possible to apply a voltage (supply power) to the control unit 130 while charging the capacitor 142 with the voltage V <b> 1 of the power generation element 140. Therefore, the control unit 130 operates stably. In the control unit 130, the voltage of the capacitor 142 and the control unit 130 is lower than the voltage V1 of the power generation element 140 by a forward voltage of the diode 141 (voltage V2).

  Further, a single crystal silicon solar cell can be used as the power generation element 140. Single-crystal silicon solar cells generate power not only with visible light but also with infrared light. Therefore, the power generation element 140 can perform not only power generation by ambient light (visible light) but also power generation by infrared light from the camera 200 (FIG. 1). In this case, the voltage V <b> 1 of the power generation element 140 changes according to the amount of infrared light from the camera 200. For example, when the tag 100 is located within the angle of view of the camera 200, infrared light is emitted from the camera 200 to the tag 100, and thus the voltage V1 (generated power) of the power generation element 140 increases. On the contrary, when the tag 100 is located outside the angle of view of the camera 200, the tag 100 is not irradiated with infrared light, so the voltage V1 of the power generation element 140 becomes small. By utilizing this principle, information can be transmitted from the camera 200 to the tag 100A as described below.

  In the graph shown in FIG. 12B, the horizontal axis indicates time, and the vertical axis indicates voltage. In the example shown in FIG. 12B, the control unit 130 repeatedly executes tag information transmission at intervals. Specifically, tag information is transmitted from time 0 to t110 and time t140 to t150, and tag information is not transmitted until transmission of the next tag information starts from time t110 to t140 and time t150.

  Specifically, at time 0 to t110 and time t140 to t150, the control unit 130 switches the on and off states of the liquid crystal 120, so that the infrared light emitted from the camera 200 is reflected so as to include tag information. To do. For this reason, since the power consumed by the control unit 130 is covered not only by the power generation element 140 but also by the discharge from the capacitor 142, the voltage V2 of the capacitor and the voltage V1 of the power generation element 140 both decrease.

  On the other hand, after time t110 to t120 and after time t150, tag information is not transmitted, and the control unit 130 does not switch the liquid crystal 120 between the on state and the off state. For this reason, since the capacitor 142 is charged with the electric power of the power generation element 140, both the voltage V2 of the capacitor and the voltage V1 of the power generation element 140 increase.

  Here, at time t120 and t130, irradiation of infrared light from the camera 200 to the tag 100A is stopped. At this time, since the amount of light received by the power generation element 140 as a solar cell (that is, the amount of power generation) decreases, the voltage V1 of the power generation element 140 greatly decreases. However, since the irradiation of infrared light from the camera 200 to the tag 100A is stopped for a short time, voltage application (power supply) to the control unit 130 is maintained by discharging the charged capacitor 142 during that period. . That is, even if the voltage V1 decreases, the voltage V2 does not decrease. As described above, if the time for stopping the irradiation of infrared light from the camera 200 to the tag 100A is relatively short, the power generation element 140 is applied while applying the voltage V2 to the control unit 130 so that the operation of the control unit 130 is not stopped. The voltage V1 can be changed.

  Therefore, information can be transmitted from the camera 200 to the tag 100 using a change in the voltage V1 of the power generation element 140. For example, the duration, the number of times of decrease (voltage drop) of the voltage V1 of the power generation element 140, and the time interval when the voltage drop appears a plurality of times can be information from the camera 200 to the tag 100. The tag 100 can receive information from the camera 200 by monitoring the voltage V <b> 1 of the power generation element 140 by the control unit 130. For example, information can be transmitted from the camera 200 to the tag 100 by Bluetooth or the like, but this involves an increase in the size of the apparatus and an increase in power consumption. On the other hand, by using the voltage V1 of the power generation element 140 as in this application example, information can be transmitted from the camera 200 to the tag 100 only by using, for example, a circuit including a diode 141 and a capacitor 142. Therefore, the apparatus is not increased in size and the power consumption is hardly increased.

[Second Embodiment]
FIG. 13 is a diagram showing a schematic configuration of an information communication system according to the second embodiment. As illustrated in FIG. 13, the information communication system 1 </ b> A includes a plurality of tags 100 a to 100 e, a camera 200 </ b> A, and a server 300.

  The information communication system 1A can measure the position of the camera 200A (details will be described later). In the example shown in FIG. 13, the tags 100a to 100e and the camera 200A are arranged inside the house 2, and the information communication system 1A can perform indoor positioning of the camera 200A.

  The tags 100a to 100e include the same configuration and function as the tag 100 of FIG.

  The camera 200 </ b> A has a function different from that of the camera 200 of FIG. 1, but may include the function of the camera 200. Furthermore, the camera 200A is configured to be able to communicate with the server 300 via a communication network.

  The server 300 stores the position information of the tags 100a to 100e. The location information is stored in the database 301 in the server 300, for example. The database 301 describes each ID of the tags 100a to 100e in association with the position information.

  The functions of the server 300 are physically realized by an IC (Integral Circuit) including a CPU, a RAM, a ROM, and the like and a communication module that is a data transmission / reception device.

  FIG. 14 is a diagram illustrating functional blocks of the camera 200A. As shown in FIG. 14, the camera 200 </ b> A includes an infrared light emitting unit 210, an infrared light receiving unit 220, a visible light receiving unit 230, a display unit 240, a decoding unit 250, an operation unit 260, a communication Unit 270, position information acquisition unit 280, measurement unit 290, and acceleration sensor 295.

  The communication unit 270 is a part that communicates with the server 300 (FIG. 13). Although the communication method is not particularly limited, for example, wireless communication between the communication unit 270 and a base station (not shown), wired communication between the base station and the server 300, or the like can be used.

  The position information acquisition unit 280 acquires the tag position information from the server 300 that stores the position information of the tags 100a to 100e (hereinafter sometimes simply referred to as the tag 100a) based on the decoding result of the decoding unit 250. It is a part to do.

  The measurement unit 290 is acquired by the position information acquisition unit 280 and at least one of imaging data of the plurality of tags 100a and the like and distance data between the camera 200A and the plurality of tags 100a and the like within the angle of view of the camera 200A. This is a part (first measurement unit) for measuring the position of the camera 200A based on the obtained position information. For example, when the camera 200A is a depth camera, the distance data between the camera 200A and the plurality of tags 100a can be obtained using a depth sensor. Since the distance data is not essential, the measurement unit 290 can measure the position of the camera 200A even when the distance data cannot be acquired. In this case, the measurement unit 290 can also measure the distance between the camera 200A and each of the tags 100a based on the measured position of the camera 200A and position information such as the tag 100a.

  A modification of the measurement unit 290 is also conceivable. The measurement unit 290x as a modified example can measure the position of the camera 200A using the acceleration sensor 295. The acceleration sensor 295 functions as an attitude detection unit that detects the pitch, roll, and yaw of the camera 200A as parameters representing the attitude of the camera 200A. The measurement unit 290x includes at least one of parameters detected by the acceleration sensor 295, imaging data such as the tag 100a within the angle of view of the camera 200A, and distance data between the camera 200A and the tag 100a, and position information. This is a part (second measurement unit) that measures the position of the camera 200A based on the position information acquired by the acquisition unit 280. For example, when the camera 200A is a depth camera, the distance data between the camera 200A and the tag 100a can be acquired using a depth sensor. Since the distance data is not essential, the measurement unit 290 can measure the position of the camera 200A even when the distance data cannot be acquired. In this case, the measurement unit 290 can also measure the distance between the camera 200A and each of the tags 100a based on the measured position of the camera 200A and position information such as the tag 100a.

  Returning to FIG. 13, for example, the camera 200 </ b> A can read the tag information from the tag 100 a and inquire the server 300 about the installation location of the tag 100 a to obtain the tag. Here, when the camera 200A is a depth camera, the camera 200A can also measure the distance from the camera 200A to the tag 100a. In that case, the camera 200A can measure the position of the camera 200A based on the position of the tag 100a within the angle of view of the camera 200A and the distance to the tag 100a. However, if the distance between the camera 200A and the tag 100a is longer than the measurable distance, the camera 200A cannot measure the distance to the tag 100a. For this reason, the camera 200A cannot perform indoor positioning.

  On the other hand, when the camera 200A reads tag information from each of the plurality of tags 100a to 100e, the position of the camera 200A can be estimated and measured without performing distance measurement using a depth camera, as will be described below. it can. In addition, when the distance measurement by a depth camera is possible, the measured distance data can also be used.

  FIG. 15 is a diagram illustrating an example of an image including a plurality of tags 100a to 100e captured by the camera 200A.

  As shown in FIG. 15, the positions (installation locations) of the tags 100a to 100e can be acquired by inquiring the server 300 by acquiring the tag information (ID: 1 to ID: 5). . If the position information of the tags 100a to 100e can be acquired, based on the image data of the tags 100a to 100e in the image shown in FIG. 15 (within the angle of view of the camera 200A) and the position information of the tags 100a to 100e, The position can be calculated and obtained. Further, the distance between the camera 200A and the tag 100a or the like can be obtained by comparing the position of the camera 200A thus obtained with the position of the tag 100a or the like. The measurement unit 290 calculates the position of the camera 200A and the distance from the tag 100a and the like. In addition, the measurement of the position of the camera 200A and the measurement of the distance from the tag 100a can be performed separately as described above, for example.

  That is, for example, the position of the camera 200A is estimated by using a posture parameter in addition to the imaging data of the tag 100a and the position information by a sensor that can detect the posture parameter of the camera 200A, such as the acceleration sensor 295. Can do. Also in this case, the distance from the camera 200A to the tag 100a or the like can be calculated. Calculation of the position of the camera 200A and the distance from the tag 100a and the like is performed by the measurement unit 290x.

  The reason why the position of the camera 200A can be measured by the measurement unit 290 or the measurement unit 290x as described above can be described as follows. That is, if the tag position information can be acquired, at least one of the position within the angle of view (imaging data) and the distance data from the camera to the tag can be known. Since there are six position parameters of the unknown camera 200A, it is only necessary to measure six or more parameters related to the camera position parameters. In the case of the measurement unit 290, six known parameters can be acquired by combining any of the position within the angle of view of two or more tags and the distance data from the camera to the tag. Can be measured. On the other hand, in the case of the measurement unit 290x, three known parameters are obtained by combining at least one of the position within the angle of view of one or more tags and the distance data from the camera to the tag, and the acceleration sensor 295. By detecting three parameters of pitch, roll, and yaw, a total of six parameters can be acquired, so that the position of the camera 200A can be estimated (measured). If the position of the camera 200A can be measured, the distance to the tag 100a or the like whose position information is known can be easily calculated.

  As yet another method, for example, the distance to the tag 100a or the like can be estimated from the intensity of infrared light reflected from the tag 100a or the like received by the camera 200A. The intensity of the reflected infrared light depends on the reflection coefficient of the tag 100a and the like and the distance from the camera 200A to the tag 100a and the like. Therefore, if the reflection mechanism such as the tag 100a is known, the distance from the camera 200A to the tag 100a can be calculated based on the intensity of infrared light reflected from the tag 100a. The reflection coefficient of the tag 100a or the like can be stored in advance in the database 301 of the server 300, for example. The camera 200 </ b> A can acquire the reflection coefficient of the tag 100 a and the like from the server 300. As another method, there is a method using another camera in addition to the camera 200A as a depth camera. This will be described in a later-described modification.

  The tags 100a to 100e are not necessarily imaged at the same time. For example, a tag captured in the past by applying an image processing method such as SLAM (Simultaneously Localization and Mapping) or mounting an acceleration sensor or an angular velocity sensor on the camera 200A, and present within the current angle of view. Tags that are not used can also be used for indoor positioning. It should be noted that an image processing method such as SLAM is applied to an image group captured by a separately installed camera, and the result is used in the camera 200A, thereby stabilizing the image acquired by the camera 200A and detecting the tag more reliably. It can also be made possible.

  FIG. 16 is a flowchart illustrating an example of processing executed in the information communication system 1A (FIG. 13). Steps S201 to S205 are the same as steps S101 to S105 in FIG. That is, the camera 200A (for example, a depth camera) emits infrared light (step S201). The tag 100a or the like receives the infrared light from the camera 200A (step S202), and reflects the infrared light while switching the liquid crystal on and off (step S203). The camera 200A receives the reflected infrared light (step S204) and decodes the tag information (step S205).

  Next, the communication unit 270 of the camera 200A transmits tag information to the server 300 (step S206).

  The server 300 receives the tag information transmitted from the camera 200A (step S207).

  Then, the server 300 transmits the tag position information to the camera 200A (step S207). Specifically, the server 300 searches the database 301 describing the tag information and the tag position information in association with each other based on the tag information received in step S207. Then, the server 300 transmits the tag position information obtained by this search to the camera 200A.

  The communication unit 270 of the camera 200A receives tag position information from the server 300 (step S209). The position information acquisition unit 280 acquires tag position information.

  Then, the camera 200A measures the position of the camera 200A (step S210). Specifically, the measurement unit 290 includes at least one of imaging data such as a plurality of tags 100a within the angle of view of the camera 200A and distance data between the camera 200A and the plurality of tags 100a, and a position information acquisition unit. Based on the position information acquired by H.280, the position of the camera 200A is measured. Alternatively, the measurement unit 290x may include at least one of parameters detected by the acceleration sensor 295, imaging data such as the tag 100a within the angle of view of the camera 200A, and distance data between the camera 200A and the tag 100a. Based on the position information acquired by the position information acquisition unit 280, the position of the camera 200A is measured. Further, the distance between the camera 200A and the tag 100a may be measured. The distance measurement may be performed by another method that does not use the tag position information, for example, a method for estimating the distance from the reflected infrared light intensity to the tag 100a or the like as described above.

  Next, effects of the information communication system 1A according to the second embodiment will be described. According to the information communication system 1A, the camera 200A acquires the position information such as the tag 100a from the server 300 that stores the position information such as the tag 100a (steps S206 to S209). The camera 200A is acquired by the position information acquisition unit 280 and at least one of imaging data such as a plurality of tags 100a within the angle of view of the camera 200A and distance data between the camera 200A and the plurality of tags 100a. Based on the obtained position information, the position of the camera 200A is measured. Alternatively, the camera 200A includes at least a parameter detected by the acceleration sensor 295 (attitude parameter of the camera 200A), imaging data such as the tag 100a within the angle of view of the camera 200A, and distance data between the camera 200A and the tag 100a. Based on any of the data and the position information acquired by the position information acquisition unit 280, the position of the camera 200A is measured (step S210). Thereby, the position of the camera 200A can be measured. Further, the distance between the camera 200A and the tag 100a can be measured. Further, for example, even when the camera 200A is a depth camera and the distance from the camera 200A to the tag 100a or the like is so far as not to be measured by the depth sensor, the distance data is not obtained in the above-described method for measuring the position of the camera 200A. Since it is not essential, the position of the camera 200A can be measured.

[Modification]
FIG. 17 is a diagram illustrating a schematic configuration of an information communication system according to a modification. As illustrated in FIG. 17, the information communication system 1 </ b> C includes a tag 100, cameras 200 </ b> B and 201, and a server 300.

  The information communication system 1C measures the position of the camera 200C using two cameras, the camera 200B and the camera 201 (details will be described later).

  The camera 200B has a function different from that of the camera 200A of FIG. 13, but may include the function of the camera 200A. Furthermore, the camera 200B is configured to be able to communicate with the camera 201.

  The camera 201 is, for example, an RGB camera. The camera 201 includes a visible light receiving unit 230 that receives visible light. On the other hand, the camera 201 is different from the camera 200B in that the camera 201 does not include the infrared light emitting unit 210 and the infrared light receiving unit 220 like the camera 200B.

  That is, in the information communication system 1C, one of the two cameras, the camera 201 and the camera 200B, is a camera (camera 200B) having a function of measuring a distance to an object using infrared light, and the other Has a feature that it is a camera (camera 201) that does not have such a function.

  FIG. 18 is a diagram illustrating an example of an image including a tag 100a that is captured by two cameras, the camera 200B and the camera 201, as an example. The tags 100b to 100e are also included in the image, but are not shown here. In FIG. 18A, the position of the tag 100a in the image captured by the camera 201 is shown as a solid white circle. In FIG. 18 (a), for reference, the position of the tag 100a in the image captured by the camera 200B is shown as a dashed white circle. In FIG. 18B, the position of the tag 100a in the image captured by the camera 200B is illustrated as a solid white circle. In FIG. 18B, for reference, the position of the tag 100a in the image picked up by the camera 201 is shown as a dotted white circle.

  As illustrated in FIG. 18, when the camera 200 </ b> B and the camera 201 are arranged apart from each other, each position of the tag 100 a in the two images of the image captured by the camera 200 </ b> B and the image captured by the camera 201. Are different from each other. The degree of difference varies depending on the distances between the camera 200B and the camera 201 and the tag 100a. Therefore, the distance from the camera 200B (or camera 201) to the tag 100a can be calculated from the positional relationship of the tags in the two images. In this case, by using the method of estimating the distance from the tag based on the intensity of the infrared light reflected from the tag as described above with reference to FIG. 15, the distance from the camera 200B to the tag 100a is also used. The distance can be measured with higher accuracy.

  Here, it is important to accurately detect the position of the tag 100a in the image captured by the camera 201. When the tag 100a is outside the distance measurement range of the camera 200B, the size of the tag 100a in the image is considerably reduced. Therefore, there is a possibility that the tag 100a cannot be detected from the image captured by the camera 201.

  Therefore, based on the tag information, it is conceivable to inquire the server 300 for information regarding the characteristics of the object to which the tag 100a is attached, and to use the information. Examples of the characteristics of the object include the color (for example, red) and the shape (for example, round shape) or the size (for example, the number of pixels in the image) of the object. If the characteristics of the object are known, the position of the tag 100a can be detected by specifying the object having such characteristics in the image captured by the camera 201. Also in this case, by using the method of estimating the distance from the tag to the tag based on the intensity of the infrared light reflected from the tag as described with reference to FIG. 15, the camera 200B to the tag 100a can be used together. The distance can be measured more systematically.

  Furthermore, the size and position of the object in the camera 201 can be calculated from the position information of the tag 100a in the image captured by the camera 200B.

  In this way, a method for identifying an object with the tag 100a in an image captured by the camera 201 will be described with reference to FIG. FIG. 19 is a diagram illustrating an example of an image including a tag 100 and an object captured by two cameras, the camera 200B and the camera 201.

  As shown in FIG. 19A, in this example, the tag 100a is attached to the object 12. In addition, there are objects 11, 13, and 14 as other objects in the vicinity of the object 12.

  FIG. 19B is an image captured by the camera 201. Since the camera 201 cannot detect the tag 100a, the objects 11 to 14 are displayed as being present in the vicinity of the tag 100a. The objects 11 to 14 are candidates for the object to which the tag 100a is attached.

  FIG. 19C is an image captured by the camera 200B. The camera 200B detects the position of the tag 100a and the distance from the camera 200B to the tag 100a. In the example shown in FIG. 19C, the position of the tag 100a is represented as a black square, and the distance is represented as 4 m.

  Here, the size occupied by the object in the image captured by the camera 201 can be obtained based on the size of the object that is one of the features of the object to which the tag 100a is attached. Such processing may be executed by the camera 201, or may be executed by the measurement unit 290 or the like on the camera 200B side. In addition, when the camera 200B inquires the server 300 for information on the color or shape of the object, it is possible to accurately determine which of the objects 11 to 14 the tag 100a is attached to. In this way, in the example shown in FIG. 19, the tag 100a is attached to the object 12, and it can be determined that the object 12 is an object to be detected.

  Also according to the modification described above, the position of the camera 200B can be measured (for example, indoor positioning).

  Note that, for example, the camera 201 as an RGB camera may have a function of stabilizing a captured image and a function of tracking a moving object even when the camera 201 moves. Then, the correction information of the image for stabilizing the image and the information of the moving object are provided to the camera 200B as the depth camera, and the camera 201 uses the information to detect, track, The tag information from the tag 100a or the like may be decoded.

  The present invention is not limited to the embodiment described above. A configuration in which the characteristic portions of each embodiment and each modification are appropriately combined can also be used as the embodiment of the present invention.

  DESCRIPTION OF SYMBOLS 1 ... Information communication system, 100 ... Tag, 110 ... Retroreflective material, 120 ... Liquid crystal, 130 ... Control part, 140 ... Power generation element, 150 ... Optical filter, 160 ... Ink, 200 ... Camera, 210 ... Infrared light emission , 220 ... Infrared light receiver, 230 ... Visible light receiver, 240 ... Display part, 250 ... Decoding part, 260 ... Operation part, 270 ... Communication part, 280 ... Position information acquisition part, 290, 290x ... Measurement part 295 ... Acceleration sensor, 300 ... Server.

Claims (10)

An information communication system comprising a tag and a camera for reading information on the tag,
The tag is
A retroreflector having a reflective surface for reflecting infrared light;
Covering the reflective surface of the retroreflective material, the state is switched, and a liquid crystal capable of affecting infrared light;
A control unit that switches the state of the liquid crystal so that the infrared light reflected by the retroreflecting material includes information on the tag;
Including
The camera
A light emitting unit that emits infrared light;
A light receiving unit that receives infrared light transmitted through the liquid crystal of the tag and reflected by the retroreflecting material of the tag so as to include information on the tag among infrared light emitted by the light emitting unit; ,
A decoding unit for decoding information of the tag included in the infrared light received by the light receiving unit;
An information communication system.   The information communication system according to claim 1, wherein the camera is a depth camera capable of measuring a distance from the camera to the tag.   The information communication system according to claim 1, wherein the retroreflective material includes a plurality of retroreflective materials having different colors.   The tag according to claim 1 or 2, further comprising an optical filter that covers a surface of the liquid crystal opposite to the retroreflecting material, absorbs or reflects visible light, and transmits infrared light. Information communication system. The tag further includes:
The information communication system according to any one of claims 1 to 4, further comprising a power generation element that generates power upon receiving infrared light.   6. The information communication system according to claim 1, wherein the retroreflective material has a convex shape that is convex toward the side on which the liquid crystal is disposed or a concave shape that is concave. 7. The camera further includes:
Based on the decoding result of the decoding unit, a position information acquisition unit that acquires the position information of the tag from the server that stores the position information of the tag;
Imaging data of a plurality of tags within the angle of view of the camera, distance data between the camera and each of the plurality of tags, and the position information acquired by the position information acquisition unit Based on the measurement unit for measuring the position of the camera,
The information communication system according to claim 1, comprising: The camera further includes:
Based on the decoding result of the decoding unit, a position information acquisition unit that acquires the position information of the tag from the server that stores the position information of the tag;
An attitude detection unit for detecting the pitch, roll and yaw of the camera as parameters representing the attitude of the camera;
The parameter detected by the attitude detection unit, at least one of tag imaging data within the angle of view of the camera and distance data between the camera and the tag, and the position information acquisition unit A measurement unit for measuring the position of the camera based on the position information;
The information communication system according to claim 1, comprising:   The information according to any one of claims 1 to 8, wherein the decoding unit decodes information of the tag based on a temporal change in reflection intensity of infrared light reflected by the retroreflecting material of the tag. Communications system. An information reading method executed by a tag and a camera for reading information on the tag,
The camera emitting infrared light;
Infrared light emitted by the tag in the emitting step is transmitted through the liquid crystal and reflected by a retroreflecting material so as to include information on the tag; and
The camera receiving the infrared light reflected by the reflecting step;
Decoding the tag information contained in the infrared light received by the camera in the receiving step;
A method for reading information.

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