Object information reading system, object information reading device, object set, and object information reading method

Abstract

The purpose of the present disclosure is to provide an object information reading system capable of reading information on a plurality of objects even when the objects are arranged in an overlapping manner. The present disclosure relates to an object information reading system using electromagnetic waves, the object information reading system comprising: an object having transparency to the electromagnetic waves; and an object information reading device. The object information reading device first transmits the electromagnetic waves toward the front surface of the foremost object among objects arranged in an overlapping manner. Next, the object information reading device receives reflected electromagnetic waves that are electromagnetic waves reflected by a first reflection plate and second reflection plate included in each of the objects arranged in an overlapping manner. Next, the object information reading device uses the reflected electromagnetic waves to estimate an arrangement relationship between the first reflection plate and the second reflection plate for each of the objects arranged in an overlapping manner, and specifies the position of the first reflection plate on the object. Next, the object information reading device identifies the type of each of the objects arranged in an overlapping manner on the basis of the position of the first reflection plate.

Description

Object information reading system, object information reading device, object set, and object information reading method

[0001] The present disclosure relates to an object information reading system, an object information reading device, an object set, and an object information reading method, and more specifically to a technology for reading the type of an object using electromagnetic waves.

[0002] Research and development is being promoted on the metaverse, a three-dimensional virtual space, digital twins, and cyber-physical fusion. New services based on these technologies are also being put into practical use. Attention is being focused on input interfaces (IFs), which are a means of transferring real-world information to the virtual world.

[0003] Non-Patent Document 1 discloses a technology that uses actual cards in a card game as the object and reads information about the object by photographing it with a camera and recognizing the image. This makes it possible to display the read object information in three dimensions, providing a visual effect.

[0004] Suzuki Erina et al., "Visualization system using image recognition for trading card games using real cards," Proceedings of the 84th National Conference of the Information Processing Society of Japan, Vol. 4, 305-306 (2022).

[0005] However, when multiple objects are arranged overlapping each other, the above-described method using a camera does not ensure sufficient reading accuracy for objects that are not in the foreground relative to the camera.

[0006] In order to solve the above-mentioned problems, a first object of the present disclosure is to provide an object information reading system that can read information about an object even when multiple objects are placed overlapping each other.

[0007] A second object of the present disclosure is to provide an object information reading device that can read information about an object even when multiple objects are arranged overlapping each other.

[0008] A third object of the present disclosure is to provide a set of objects that allows the individual types to be read even when they are arranged on top of each other.

[0009] A fourth object of the present disclosure is to provide an object information reading method that can read information about an object even when multiple objects are arranged overlapping each other.

[0010] A first aspect of the present disclosure is an object information reading system using electromagnetic waves, comprising: an object that is transparent to the electromagnetic waves; and an object information reading device, wherein the object includes: a first reflector that is arranged at a position specific to the type of object and that is reflective to the electromagnetic waves; and second reflectors that are arranged at at least three predetermined points on the object and that are reflective to the electromagnetic waves; and the object information reading device performs the following processes: transmitting the electromagnetic waves toward a surface of a frontmost object among the overlapping objects; receiving reflected electromagnetic waves that are the electromagnetic waves reflected by the first reflector and the second reflector included in each of the overlapping objects; extracting reflected electromagnetic waves corresponding to each of the overlapping objects based on the reception time of the reflected electromagnetic waves; and estimating the positional relationship between the first reflector and the second reflector for each of the overlapping objects based on the extracted reflected electromagnetic waves, and identifying the position of the first reflector on the object. It is preferable that the imaging device is configured to execute a process of identifying the type of each of the objects arranged in an overlapping state based on the position of the first reflector.

[0011] A second aspect is an object information reading system using electromagnetic waves, comprising: an object that is transparent to the electromagnetic waves; an object information reading device that is arranged alongside the surface of the foremost object among the overlapping objects and that is in contact with or not in contact with the surface; and a reading circuit, wherein the object includes: a first reflector that is arranged at a position specific to the type of object and is reflective to the electromagnetic waves; and second reflectors that are arranged at at least three predetermined points on the object and are reflective to the electromagnetic waves, and the object information reading device is configured to execute the following processes: transmitting the electromagnetic waves towards an area that it is responsible for on the surface of the foremost object; receiving reflected electromagnetic waves that are the electromagnetic waves reflected by the first reflector or the second reflector included in each of the overlapping objects; and transmitting a received signal of the reflected electromagnetic waves and information about the area that it is responsible for to the reading circuit, and the reading circuit is configured to: combine the received signals of the reflected electromagnetic waves in each area based on the information about the area; It is preferable that the system is configured to execute the following processes: a process of extracting reflected electromagnetic waves corresponding to each of the overlapping objects based on the reception time of the combined reflected electromagnetic waves; a process of estimating the positional relationship between the first reflector and the second reflector for each of the overlapping objects based on the extracted reflected electromagnetic waves, and specifying the position of the first reflector on the object; and a process of identifying the type of object for each of the overlapping objects based on the position of the first reflector.

[0012] A third aspect is preferably an object information reading device configured to perform the following processes: transmitting electromagnetic waves toward the surface of the foremost object among the overlapping objects; receiving reflected electromagnetic waves, which are the electromagnetic waves reflected by a first reflector and a second reflector included in each of the overlapping objects; extracting reflected electromagnetic waves corresponding to each of the overlapping objects based on the reception time of the reflected electromagnetic waves; estimating the positional relationship between the first reflector and the second reflector for each of the overlapping objects based on the extracted reflected electromagnetic waves, and specifying the position of the first reflector on the object; and identifying the type of object for each of the overlapping objects based on the position of the first reflector.

[0013] A fourth aspect is an object set including a plurality of objects, wherein the objects preferably include a first reflector that is transparent to electromagnetic waves and reflective to the electromagnetic waves, arranged at a specific position corresponding to each type of object, and a second reflector that is reflective to the electromagnetic waves, arranged at at least three predetermined points.

[0014] A fifth aspect is a method for reading information about an object that is transparent to electromagnetic waves, the method comprising: transmitting the electromagnetic waves toward a surface of the frontmost object among the overlapping objects; receiving reflected electromagnetic waves that are the electromagnetic waves reflected by a first reflector and a second reflector included in each of the overlapping objects; extracting reflected electromagnetic waves corresponding to each of the overlapping objects based on the reception time of the reflected electromagnetic waves; estimating a positional relationship between the first reflector and the second reflector for each of the overlapping objects based on the extracted reflected electromagnetic waves, and specifying the position of the first reflector on the object; and identifying the type of the object for each of the overlapping objects based on the position of the first reflector, wherein it is preferable that the first reflector is arranged at a unique position on the object depending on the type of object, and the second reflector is arranged at at least three predetermined points on the object.

[0015] In the present disclosure, an object that is transparent to electromagnetic waves is used. A first reflector that is reflective to the electromagnetic waves is disposed on the object at a position specific to the type of object. The object information reading device identifies the type of object by using the electromagnetic waves to identify the position of the upper first reflector. This makes it possible to provide an object information reading system, object information reading device, and object information reading method that can read information on multiple objects even when they are placed overlapping each other. It is also possible to provide an object set that can read the individual types of objects even when they are placed overlapping each other.

[0016] FIG. 1 is a diagram showing an object information reading system according to a first embodiment of the present disclosure. FIG. 2 is a diagram showing a first reflector and a second reflector arranged on a card according to a first embodiment of the present disclosure. FIG. 3 is a block diagram showing an example of a functional configuration of an object information reading device according to a first embodiment of the present disclosure. FIG. 4 is a flowchart of processing executed by an object information reading device according to a first embodiment of the present disclosure. FIG. 5 is a diagram explaining the effect of arranging a first reflector and a second reflector according to a modified example of the first embodiment of the present disclosure. FIG. 6 is a diagram explaining an object information reading system according to a modified example of the first embodiment of the present disclosure.

[0017] Embodiments of the present disclosure will be described with reference to the drawings. The same or corresponding components will be designated by the same reference numerals, and repeated description may be omitted.

[0018] 1 is a diagram showing an object information reading system 100 according to a first embodiment of the present disclosure. The object information reading system 100 includes a plurality of objects arranged in a stacked manner and an object information reading device 2. For the sake of explanation, the object is assumed to be a card 1. The card 1 may be, for example, a card used in a trading game, a pass card, or the like, but is not limited thereto.

[0019] Card 1 is transparent to terahertz waves 10. First reflector 11 and second reflector 12 are arranged on the surface or inside card 1. First reflector 11 and second reflector 12 are made of metal that is reflective to terahertz waves 10.

[0020] The object information reading device 2 is placed above or below the stacked cards 1. The object information reading device 2 may be in a non-contact state with the cards 1, or may be in contact with the frontmost or rearmost card 1.

[0021] The object information reader 2 transmits terahertz waves 10 toward the surface of the frontmost card 1 among the cards 1 arranged in a stack.

[0022] The transmitted terahertz waves 10 pass through the cards 1 and can reach the rearmost card 1 even when cards 1 are stacked. However, a portion of the transmitted terahertz waves 10 is reflected each time by the first reflector 11 and the second reflector 12 included in each of the stacked cards 1. The reflected terahertz waves 20 reflected by the first reflector 11 and the second reflector 12 return to the object information reading device 2 in a time period that depends on the distance between the card 1 including the first reflector 11 and the second reflector 12 and the object information reading device 2. The object information reading device 2 extracts the reflected terahertz waves 20 corresponding to each of the stacked cards 1 based on the reception time of the reflected terahertz waves 20.

[0023] Based on the received reflected terahertz waves 20, the object information reading device 2 identifies the position of the first reflector 11 on the card 1 from the relative positions of the first reflector 11 and the second reflector 12 for each of the overlapping cards 1. Furthermore, based on the identified position of the first reflector 11, the type of card 1 on which the first reflector 11 is placed is identified.

[0024] In this manner, in the present disclosure, information on card 1 is identified using terahertz waves 10. By using terahertz waves 10, the relative positions of first reflector 11 and second reflector 12 can be estimated more precisely than when electromagnetic waves of a lower frequency than terahertz waves 10 are used, and the position of first reflector 11 can be identified with high accuracy. This makes it possible to identify information on card 1 with high accuracy. Note that the electromagnetic waves used in the present disclosure are not limited to terahertz waves 10, but may also be millimeter-wave electromagnetic waves in the fifth-generation mobile communication system (5G). For example, millimeter-wave electromagnetic waves of 25 GHz or higher can achieve the same effect as described above.

[0025] 2 is a diagram showing a first reflector 11 and a second reflector 12 arranged on a card 1 according to the first embodiment of the present disclosure. The arrangement position of the first reflector 11 is specific to the type of card 1. That is, cards 1 of the same type have the first reflector 11 arranged in the same position. On the other hand, cards 1 of different types have the first reflector 11 arranged in different positions.

[0026] The first reflector 11 may be disposed in one location on the card 1, or in multiple locations. The first reflector 11 may also be a two-dimensional pattern such as a QR code (registered trademark). The metal density of the first reflector 11 may be reduced within a range that allows the terahertz waves 10 to be reflected. By reducing the metal density, the first reflector 11 can be disposed without impairing the appearance of characters, illustrations, etc. printed on the card.

[0027] Additionally, second reflectors 12 are disposed at three predetermined points among the four corners of each card 1. The second reflectors 12 are disposed at predetermined positions regardless of the type of card 1. By disposing the second reflectors 12, the object information reading device 2 that receives the reflected terahertz waves 20 reflected by the second reflectors 12 can determine the size of the card 1 on which the second reflectors 12 are disposed. By determining the size of the card 1, the position of the first reflectors 11 on the card 1 can also be determined.

[0028] The second reflectors 12 may be placed at all four corners of each card 1, but by placing them at three of the four corners, it becomes possible to distinguish the top and bottom of the card 1 in addition to the size of the card.

[0029] It is desirable that the material of second reflector 12 contains, in addition to a metal that is reflective to terahertz waves 10, a dielectric that is transparent to terahertz waves 10. This allows a portion of terahertz waves 10 to pass through second reflector 12, and in multiple cards 1 in which second reflectors 12 are positioned almost vertically overlapping, terahertz waves 10 can be propagated to the rearmost surface.

[0030] Similarly, the material of first reflector 11 may also contain a dielectric that is transparent to terahertz waves 10. By allowing a portion of terahertz waves 10 to pass through first reflector 11, terahertz waves 10 can be propagated to subsequent cards 1 even when cards 1 of the same type are stacked on top of each other.

[0031] 3 is a block diagram showing an example of a functional configuration of an object information reading device 2 according to the first embodiment of the present disclosure. The transmitter 21 of the object information reading device 2 includes a laser light source and a transmitting antenna, and transmits terahertz waves 10 toward the surface of the frontmost card 1 among the stacked cards 1. The frequency of the terahertz waves 10 may be a single frequency, a continuous frequency, or multiple discrete frequencies. By using terahertz waves 10 of continuous or discrete frequencies, the receiver 22 can obtain reflected terahertz waves 20 at multiple frequencies, thereby improving the reliability of the data and increasing the accuracy of identifying card information.

[0032] The receiver 22 includes a receiving antenna, an analog processing circuit, and a digital processing circuit. The receiver 22 receives reflected terahertz waves 20, which also include terahertz waves 10 that have returned directly to the receiver 22 after being transmitted from the transmitter 21 without being reflected by the first reflector 11 and the second reflector 12. The receiver 22 removes this direct terahertz wave 10, and transmits only the terahertz waves 10 reflected by the first reflector 11 and the second reflector 12 to the reading circuit 23.

[0033] Although the number of transmitting antennas and receiving antennas is not limited, using an array antenna consisting of a plurality of antennas enables beamforming of terahertz waves 10 during transmission and reflected terahertz waves 20 during reception. This makes it possible to form a highly directional beam, improving the reception efficiency of reflected terahertz waves 20 at receiver 22.

[0034] The reading circuit 23 stores a list 50 that associates the position of the first reflector 11 on the card 1 with the type of card 1 .

[0035] The reading circuit 23 extracts the reflected terahertz waves 20 corresponding to each of the overlapping cards 1 based on the reception time of the reflected terahertz waves 20. Furthermore, the reading circuit 23 estimates the relative positions of the first reflector 11 and the second reflector 12 on the card, and identifies the position of the first reflector 11 on the card 1 for each of the overlapping cards 1. Furthermore, the reading circuit 23 compares the identified position of the first reflector 11 on the card 1 with a pre-stored list 50, thereby identifying the type of card on which the first reflector 11 is placed.

[0036] The processing performed by the reading circuit 23 of the object information reading device 2 may be executed by a program using a computer equipped with a CPU and memory and storing a program in the memory. Alternatively, the processing may be executed by a program using an integrated circuit such as an FPGA (Field Programmable Gate Array). The program may be provided by being recorded on a storage medium or via a network. This point is common to all of the following embodiments.

[0037] FIG. 4 is a flowchart of processing executed by the object information reading device 2 according to the first embodiment of the present disclosure. First, the processing is started. Next, the transmitter 21 transmits terahertz waves 10 toward the surface of the frontmost card 1 among the stacked cards 1 (step S01). Next, the receiver 22 receives reflected terahertz waves 20 reflected by the first reflector 11 and the second reflector 12 included in the card 1 (step S02). Next, the reading circuit 23 identifies the position of the first reflector 11 on each of the stacked cards 1 based on the reflected terahertz waves 20 (step S03). Next, the reading circuit 23 identifies the type of card on which the first reflector 11 is located based on the identified position of the first reflector 11 on the card 1 (step S04). Finally, the processing ends.

[0038] As described above, the object information reading system 100 of the present disclosure uses a card 1 that is transparent to terahertz waves 10. A first reflector 11 that is reflective to terahertz waves 10 is disposed on the card 1 at a position specific to the type of card. The object information reading device 2 identifies the type of card by using terahertz waves 10 to identify the position of the first reflector 11 on the card 1. This makes it possible to provide an object information reading system, an object information reading device, and an object information reading method that can read card information even when multiple cards are placed on top of each other. It is also possible to provide an object set that can read each type of card even when the cards are placed on top of each other.

[0039] <First Modification of First Embodiment> The reading circuit 23 does not necessarily have to be built into the object information reading device 2, but may be located outside the device. In this case, there is no need to identify the type of card 1 within the object information reading device 2, thereby reducing the load.

[0040] <Second Modification of First Embodiment> The second reflector 12 does not necessarily have to be placed at the corners of the card 1, but may be placed at at least three predetermined points on the card 1. Even in this case, it is possible to identify the position of the first reflector 11 on the card 1 from the relative positions of the first reflector 11 and the second reflector 12.

[0041] <Third Modification of First Embodiment> In the above description, it has been explained that the reflected terahertz waves 20 reflected by the first reflector 11 and the second reflector 12 return to the object information reading device 2 in a time period that depends on the distance between the object information reading device 2 and the card 1 including the first reflector 11 and the second reflector 12. However, this is not the case when the object information reading device 2 transmits diffusive terahertz waves 10 as shown in FIG.

[0042] 5 is a diagram illustrating the effect of arranging the first reflector 11 and the second reflector 12 according to a modified example of the first embodiment of the present disclosure. Here, a side view of the overlapping cards 1 is shown. For the sake of explanation, the first reflector 11 and the second reflector 12 are shown protruding from the surface of the card 1, but this is not necessarily the case in practice.

[0043] In the case of FIG. 5, the distance that the reflected terahertz wave 20 propagates from the card 1 toward the object information reader 2 varies depending on where on the card 1 the reflected terahertz wave 20 is reflected.

[0044] Therefore, the time at which the reflected terahertz waves 20 are received by the object information reading device 2 also varies depending on where on the card 1 the reflected terahertz waves 20 are reflected. In other words, the time at which the reflected terahertz waves 20 are received varies depending on the positions of the first reflector 11 and the second reflector 12 on the card 1. Hereinafter, this is referred to as the placement effect.

[0045] As described above, the reading circuit 23 extracts the reflected terahertz waves 20 corresponding to each of the overlapping cards 1 based on the reception time of the reflected terahertz waves 20. The reception time of the reflected terahertz waves 20 is dispersed due to the placement effect, making it difficult to extract the reflected terahertz waves 20 corresponding to each of the overlapping cards 1.

[0046] Therefore, in the above-described reading circuit 23, the diffusion angle of terahertz wave 10 may be taken into consideration and the reception time of reflected terahertz wave 20 may be corrected so that it does not depend on the arrangement positions of first reflector 11 and second reflector 12 on card 1. This makes it possible to correct the arrangement effect and clarify the correspondence between reflected terahertz wave 20 and card 1.

[0047] <Fourth Variation of First Embodiment> Furthermore, in order to achieve the placement effect, it is also effective to arrange a plurality of object information readers 2 side by side on the surface of the frontmost card 1, as shown in FIG. 6 , and have each object information reader 2 transmit terahertz waves 10 with low diffusibility. FIG. 6 is a diagram illustrating an object information reading system 100 according to a variation of the first embodiment of the present disclosure. The plurality of object information readers 2 transmit terahertz waves 10 directed toward their respective areas on the surface of the frontmost card 1. Furthermore, the plurality of object information readers 2 receive reflected terahertz waves reflected by the first reflector 11 or the second reflector 12 included in each of the overlapping cards 1. Note that the object information readers 2 may be in contact with the surface of the frontmost card 1, or may be non-contact.

[0048] By using terahertz waves 10 with little diffusion, it is not necessary to consider the above-mentioned placement effect. Furthermore, by arranging multiple object information readers 2 side by side on the surface of the frontmost card 1, terahertz waves 10 can be propagated to the surface of card 1 without omission. This allows reflected terahertz waves 20 reflected by first reflector 11 and second reflector 12 included in card 1 to be received by all of the multiple object information readers 2 without omission.

[0049] In this modification, it is desirable to place a single reading circuit 23 outside the object information reading device 2. In this case, each object information reading device 2 transmits the received signal of the reflected terahertz waves 20 and information about the area it is responsible for to the external reading circuit 23. The reading circuit 23 collects the received signal of the reflected terahertz waves 20 and the information about the area it is responsible for from all the object information reading devices 2. The reading circuit 23 combines the received signal of the reflected terahertz waves 20 for each area based on the area information. This allows the reflected terahertz waves 20 to be extracted for each of the overlapping cards 1, as in the first embodiment. Furthermore, as in the first embodiment, the reading circuit 23 identifies the type of each of the overlapping cards 1 based on the information about the reflected terahertz waves 20.

[0050] <Fifth Modification of First Embodiment> In the first embodiment, a case where a plurality of cards 1 are arranged in a stack has been described. However, it should be noted that the object information reading system 100 disclosed herein can read the type of card by the above-described method even when there is only one card 1.

[0051] Sixth Modification of First Embodiment Note that the above description has been given of the case where the target object is card 1. However, the type of target object is not limited as long as it is transparent to terahertz waves 10 and has first reflector 11 and second reflector 12 disposed on or inside the surface of the target object.

[0052] <Seventh Modification of First Embodiment> In the present disclosure, it has been described that electromagnetic waves in the millimeter wave band or the terahertz region are used. The reason for this is that the relative positional relationship between the first reflector 11 and the second reflector 12 can be observed more precisely than when electromagnetic waves of frequencies lower than the millimeter wave band or the terahertz region are used, and information on the card 1 can be identified with high accuracy. It should be noted that electromagnetic waves with frequencies equal to or higher than those in the terahertz region, not limited to those in the millimeter wave band or the terahertz region, can observe the relative positional relationship between the first reflector 11 and the second reflector 12 with precision equal to or higher than that of electromagnetic waves in the terahertz region, and can identify information on the card 1 with high accuracy. Therefore, in the present disclosure, it is sufficient to use electromagnetic waves with frequencies equal to or higher than those in the millimeter wave band, and the same effect as described above can be obtained in this case.

[0053] The present disclosure is not limited to the above-described embodiments, and various modifications can be made in the implementation stage without departing from the spirit of the present disclosure. Furthermore, the embodiments and modifications may be implemented in appropriate combinations, in which case the combined effects can be obtained.

[0054] REFERENCE SIGNS LIST 1 Card, 2 Object information reading device, 10 Terahertz wave, 11 First reflector, 12 Second reflector, 20 Reflected terahertz wave, 21 Transmitter, 22 Receiver, 23 Reading circuit, 50 List, 100 Object information reading system

Claims

1. A system for reading information about an object using electromagnetic waves, comprising: an object that is transparent to the electromagnetic waves; and an object information reading device, wherein the object includes a first reflector that is arranged at a position specific to the type of object and is reflective to the electromagnetic waves; and a second reflector that is arranged at at least three predetermined points on the object and is reflective to the electromagnetic waves, wherein the object information reading device performs the following processes: transmitting the electromagnetic waves toward a surface of a foremost object among the objects that are arranged in an overlapping state; receiving reflected electromagnetic waves that are the electromagnetic waves reflected by the first reflector and the second reflector included in each of the objects that are arranged in an overlapping state; extracting reflected electromagnetic waves corresponding to each of the objects that are arranged in an overlapping state based on a reception time of the reflected electromagnetic waves; estimating a positional relationship between the first reflector and the second reflector for each of the objects that are arranged in an overlapping state based on the extracted reflected electromagnetic waves, and specifying a position of the first reflector on the object; and identifying a type of the object for each of the objects that are arranged in an overlapping state based on the position of the first reflector. An object information reading system configured to execute the above steps.

2. The object information reading system according to claim 1, wherein the first reflector reflects a portion of the electromagnetic wave and transmits a portion of the electromagnetic wave.

3. An object information reading system as described in claim 1 or 2, wherein the electromagnetic waves transmitted by the object information reading device are diffusive electromagnetic waves, and the object information reading device further performs a process of taking into account the diffusion angle of the electromagnetic waves and correcting the reception time of the reflected electromagnetic waves so that it is not dependent on the positions of the first reflector and the second reflector on the object.

4. An object information reading system using electromagnetic waves, comprising: an object that is transparent to the electromagnetic waves; an object information reading device that is arranged side by side on the surface of the foremost object among the overlapping objects, and that is in contact with or without contact with the surface; and a reading circuit, wherein the object includes a first reflector that is arranged in a unique position depending on the type of object and is reflective to the electromagnetic waves; and a second reflector that is arranged at at least three predetermined points on the object and is reflective to the electromagnetic waves, and the object information reading device is configured to execute a process of transmitting the electromagnetic waves toward an area that it is responsible for on the surface of the foremost object, a process of receiving reflected electromagnetic waves that are the electromagnetic waves reflected by the first reflector or the second reflector included in each of the overlapping objects, and a process of transmitting a received signal of the reflected electromagnetic waves and information of the area that it is responsible for to the reading circuit, and the reading circuit is configured to perform a process of combining the received signals of the reflected electromagnetic waves in each area based on the information of the area, An object information reading system configured to execute the following processes: a process of extracting reflected electromagnetic waves corresponding to each of the overlapping objects based on a reception time of the combined reflected electromagnetic waves; a process of estimating a positional relationship between the first reflector and the second reflector for each of the overlapping objects based on the extracted reflected electromagnetic waves, and identifying a position of the first reflector on the object; and a process of identifying a type of the object for each of the overlapping objects based on the position of the first reflector.

5. An object information reading device configured to perform the following processes: transmitting electromagnetic waves toward the surface of the foremost object among overlapping objects; receiving reflected electromagnetic waves which are the electromagnetic waves reflected by a first reflector and a second reflector contained in each of the overlapping objects; extracting reflected electromagnetic waves corresponding to each of the overlapping objects based on the reception time of the reflected electromagnetic waves; estimating the relative position of the first reflector and the second reflector for each of the overlapping objects based on the extracted reflected electromagnetic waves, and identifying the position of the first reflector on the object; and identifying the type of object for each of the overlapping objects based on the position of the first reflector.

6. An object set including a plurality of objects, each of which is transparent to electromagnetic waves and includes a first reflector that is reflective to the electromagnetic waves and arranged at a unique position corresponding to each type of object, and a second reflector that is reflective to the electromagnetic waves and arranged at at least three predetermined points.

7. A method for reading information about an object, which reads information from an object that is transparent to electromagnetic waves, comprising: transmitting the electromagnetic waves toward a surface of a foremost object among the objects that are arranged in an overlapping state; receiving reflected electromagnetic waves that are the electromagnetic waves reflected by a first reflector and a second reflector included in each of the objects that are arranged in an overlapping state; extracting reflected electromagnetic waves corresponding to each of the objects that are arranged in an overlapping state based on a reception time of the reflected electromagnetic waves; estimating a positional relationship between the first reflector and the second reflector for each of the objects that are arranged in an overlapping state based on the extracted reflected electromagnetic waves, and specifying a position of the first reflector on the object; and identifying a type of the object for each of the objects that are arranged in an overlapping state based on the position of the first reflector, wherein the first reflector is arranged in a position that is unique to the type of the object on the object, and the second reflector is arranged at least at three predetermined points on the object.

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