JP5674264B2 - Tag 3D position detection system - Google Patents

Description

  The present invention relates to a tag three-dimensional position detection system capable of detecting a three-dimensional position of a tag, and more particularly to a tag three-dimensional position detection system in which no false detection occurs.

A conventional system capable of detecting the three-dimensional position of a tag is disclosed in, for example, Japanese Patent Application Laid-Open No. 2007-170818 (Patent Document 1). According to this publication, a plurality of antennas are provided at different positions on a plane, and the position of the wireless tag is detected in three dimensions by switching the output from the antennas.
JP 2007-170818 A (summary, paragraph number 0029, etc.)

  A conventional system capable of detecting the three-dimensional position of a tag is configured as described above. The three-dimensional position was detected by switching the output from the antenna and determining whether or not communication with the wireless tag was possible. However, the communication range by the output from the antenna does not have a dome shape as shown in Patent Document 1, but actually a small dome-shaped communication range occurs on both sides thereof. This will be described below.

  FIG. 12 shows a state in which a trigger signal level that enables communication by placing a tag at a height of 2.5 m in the center of a pair of antennas arranged at a distance of 1 m on the plane is output from the antenna. It is a figure which shows the communication possible area | region. The abscissa and ordinate represent the distance from the point directly below the tag, with the point on the plane where the antenna is located as the origin. As shown in FIG. 12, the trigger signal shows a peak level immediately above the origin, but the tag can be detected immediately below and on both sides thereof (position about 2 m away from the origin). In this example, although it is necessary to selectively communicate with a tag in the communicable region (for example, a tag located in the vicinity of the peak value), the detection level on both sides is about 1 / peak of the peak value at the center. 3 is also available, so it is possible to communicate with a tag present at this position. Therefore, if the trigger signal has such a level, there is a possibility of detecting a tag present not only in the vicinity of the origin but also at a position away from it. In other words, in the case of a conventional system, it is necessary to perform unnecessary communication with a tag that is not to be detected in the vicinity of the origin, or depending on the level of the trigger signal, an error due to detection of a tag that should not be detected is detected. There was a problem that detection occurred.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide a tag three-dimensional position detection system capable of efficiently and reliably detecting a tag three-dimensional position.

  The tag three-dimensional position detection system according to the present invention is provided on a plane, and includes a trigger signal output means for outputting a predetermined trigger signal, and a cancel signal output for canceling a part of the trigger signal output by the trigger signal output means. Means and an upward position detecting means for detecting the upward position of the tag responding to the trigger signal using the trigger signal partially canceled by the cancel signal output means.

  In the present invention, since a cancel signal for canceling a part of the trigger signal is provided so that a portion that should not be detected does not react, a tag three-dimensional position detection system capable of reliably detecting the three-dimensional position of the tag is provided. Can be provided.

  Preferably, the cancel signal output means includes a restricting means for changing an output of the cancel signal and restricting an upward position of the tag responding to the trigger signal.

  The trigger signal output means is a trigger antenna that is provided on a plane and surrounds a predetermined range, and the cancellation means is a cancel antenna that is provided in the vicinity of the trigger antenna and outputs a cancel signal.

  More preferably, the cancel signal data and the trigger signal data have a complement relationship with each other.

  The trigger antenna may include a plurality of antennas that are spaced apart from each other in the first direction on the plane and that output different trigger signals.

  The trigger antenna includes a plurality of antennas that are spaced apart from each other in a second direction intersecting the first direction on the plane and that output different trigger signals.

  The cancel signal output means includes a plurality of trigger signal output means for outputting different trigger signals, and the upward position detection means detects the tag in response to the signals from the plurality of trigger signal output means, thereby generating a trigger signal. The upward position of the responding tag may be detected.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram showing a configuration of a tag three-dimensional position detection system. Referring to FIG. 1, the tag three-dimensional position detection system is an active tag system, and an ID tag (hereinafter abbreviated as “tag”) 20 that outputs a predetermined ID (Identification) signal; A tag position detection device 10 that detects the three-dimensional position of the tag 20 is included. The tag position detection device 10 includes a control unit 11 that controls the entire device, a trigger signal transmission unit 12 that generates a unique ID signal, a reception unit 13 that receives a response from the tag, and a trigger signal transmission unit 12. A cancel signal transmitting unit (cancellation signal output means) 14 for outputting a cancel signal for canceling a part of the trigger signal, and a display unit 15 for displaying the ID of the detected tag based on the data received by the receiving unit 13; A coil-shaped trigger antenna (trigger signal output means) 16 that transmits a trigger signal from the trigger signal transmitter 12 and a coil-shaped cancel antenna (cancel signal output means) that transmits a cancel signal from the cancel signal transmitter 14 17 and the like. The trigger antenna 16 and the cancel antenna 17 have a coil shape, and a magnetic field is generated around the coil by a high-frequency current flowing therethrough. The tag 20 outputs its own ID in response to this magnetic field, and the receiving unit 13 receives it. At this time, the tag 20 transmits radio waves including ID information at intervals of, for example, several milliseconds to several tens of milliseconds depending on the energy of the battery that the tag 20 has.

  The shapes of the trigger antenna 16 and the cancel antenna 17 are arbitrary, and may be configured as a rectangular loop antenna having a side of 1 m or a circular loop antenna having a diameter of 1 m. The trigger antenna 16 and the cancel antenna 17 are provided at substantially the same position.

  Note that the control unit 11 of the tag position detection device 10 reads the data detected by the receiving unit 13 from the tag 20, thereby identifying ID information (tag ID and trigger ID or tag ID) of the tag 20 exposed to the magnetic field of the trigger antenna 16. Area ID). Here, the trigger ID is an ID that identifies the trigger antenna 16, and the area ID is an ID that identifies a position. If the trigger antenna 16 is specified, the position can be specified.

  That is, the trigger antenna 16 outputs a trigger signal that activates the tag 20. When a trigger signal including a trigger ID is output from the trigger antenna 16, the tag 20 outputs its own ID together with the received ID (or area ID) of the trigger antenna 16 in response to the signal. The receiving unit 13 receives these pieces of information, and the control unit 11 knows the area where the tag 20 exists.

  Next, the configuration of the tag 20 will be described. FIG. 2 is a block diagram showing a schematic configuration of the tag 20. Referring to FIG. 2, tag 20 includes an antenna 22 that detects a trigger signal output from trigger antenna 16, a transmission circuit 23, a CPU 21, an amplifier 24, and a detection circuit 25 that detects a trigger signal. Including. The CPU 21 controls the operation of the entire tag 20 and is driven by the battery 26. When the detection circuit 25 detects a trigger signal from the outside via the antenna 22, a tag ID stored in a memory (not shown) is transmitted by the transmission circuit 23 and output to the outside via the antenna 22 together with the trigger ID. This is received by the receiving unit 13.

  Next, the cancel antenna 17 that outputs a cancel signal for canceling the trigger signal in this embodiment will be described. The cancel antenna 17 uses a reception area limiting method in the magnetic field. The high-frequency magnetic fields that overlap and interfere with each other become pulse code modulation signals that have a complement relationship such that when the pulse code modulation signals are overlapped, the gap between the signals is compensated. Therefore, if such a high-frequency magnetic field that interferes is generated from the trigger antenna 16 and the cancel antenna 17, the area portion where the magnetic field strength is approximated in the overlapping area where the high-frequency magnetic fields overlap is the pulse code modulation signal. Since the gaps are filled with each other at approximate potential levels, the control unit 11 cannot detect the pulse code modulation signal included in the high-frequency magnetic field. In other words, this range (the range of the overlapping area in which the magnetic field strength approximates within the overlapping area where the high-frequency magnetic field overlaps) is an invalid area (detection insensitive area) that cannot be detected even in the high-frequency magnetic field area. ) As a result, the area where the high frequency magnetic field that can be detected by the coil of the trigger antenna 16 can be limited, and a cancel signal for canceling the trigger signal can be obtained.

  The cancel signal may be output from the trigger antenna 16 by changing (for example, reducing) the level of the trigger signal. In this way, the receiving unit 11 can selectively receive this trigger signal as a cancel signal, and a cancel antenna is not required.

  Next, a method for limiting the detectable area of the high-frequency magnetic field will be specifically described with reference to the drawings. FIG. 3 is a diagram showing an arrangement of three adjacent trigger antennas 31 to 33 and three cancellation antennas 41 to 43 in the tag three-dimensional position detection system. In the figure, the trigger antenna and the cancel antenna are displayed in a shifted manner, but they may actually overlap. Note that a predetermined current flows through the terminals 311 and 312 of the rectangular antenna constituting the trigger antenna 31. The same applies to the cancel antennas 41 to 43.

  Next, a cancel trigger in the tag detection system according to this embodiment will be described. FIG. 4 is a diagram for explaining a cancel trigger signal in this embodiment. Magnetic fields 32a to 32c, which are output from the trigger antenna 32 and the cancel antenna 42 located in the center in FIG. 42a to 42c are shown. In addition, the same magnetic field output from trigger antenna 31a-31c, 33a-33c and cancellation antenna 41a-41c, 43a-43c is formed in these both sides.

  Referring to FIG. 4, when a current is passed through trigger antenna 32 in a trigger region surrounded by trigger antenna 32 that generates a predetermined trigger signal, a magnetic field is generated around trigger antenna 32. The magnetic field has a magnetic field 32a at the center, and additional magnetic fields 32b and 32c as shown in FIG. Since the magnetic fields 32b and 32c are unnecessary, in the present embodiment, the additional magnetic fields 32b and 32c are canceled by using the above-described high-frequency magnetic field limiting method. In the figure, the trigger antenna 32 has terminals 321 and 322, and the cancel antenna 42 has terminals 421 and 422.

  Magnetic fields 42a-42c are the magnetic fields generated for this cancellation. This magnetic field has a magnetic field 42a in the center and magnetic fields 42b and 42c on both sides thereof. As shown in FIG. 4, the magnetic field 42a has a slightly lower magnetic field intensity over the entire magnetic field 32a. If such a magnetic field 42a is used for canceling the magnetic field 32a, only the tag located above in the trigger region surrounded by the trigger antenna 32 can be reacted.

  That is, the trigger ID including an area ID for specifying a predetermined area can be detected. In the receivable area, the tag can detect only the area ID data, and the cancel area can detect both the area ID data and the magnetic field for cancellation. An invalid signal that does not become ID data is detected. As a result, it is possible to detect only tags that are separated from the trigger antenna to a specific distance.

  The trigger signal is output in such a manner that the canceling magnetic field is first output from the canceling antenna to a predetermined strength, and then the triggering magnetic field having the area ID data is output from the triggering antenna. This prevents erroneous tag activation during trigger magnetic data level fluctuations.

  Further, the cancel antenna may change the output of the cancel signal to limit the upward position of the tag responding to the trigger signal. In this case, the control unit 11 and the cancel antenna operate as limiting means.

  Next, a specific method for canceling the trigger signal will be described. FIG. 5 shows a trigger signal (A) for outputting area ID data, a cancel signal (B) for outputting a cancel signal for canceling the area ID, and a signal (C) obtained by adding the trigger signal and the cancel signal. It is a schematic diagram. In the figure, a portion indicated by a rectangle having a vertical line is signal 1, and a gap portion indicates signal 0. Area ID data for specifying an area includes a preamble portion made up of a signal 1 having a fixed length (n bits) and a portion that repeats signals 1 and 0 for each bit.

  Cancel data is a signal that repeats signals 1 and 0 for each bit. That is, the trigger signal (A) is shifted by 1 bit of data with respect to the cancel signal (B).

  The signal obtained by adding the trigger signal and the cancel signal shown in FIG. 5C is a continuous signal of data 1, and the trigger signal is not formed in the detected range of this signal, and is not recognized as the trigger signal. It is possible to completely cancel the trigger signal by adjusting the intensity of the cancel signal. Further, by devising the arrangement of the cancel antenna, it is possible to cancel a trigger signal at an arbitrary position such as only the central portion (for example, only 32a) or only both end portions (for example, only 32b and 32c).

  Next, another embodiment of the cancel signal will be described. FIG. 6 is a diagram showing another embodiment of the cancel signal. In the embodiment shown in FIGS. 3 and 4, trigger antennas 31 to 33 and cancel antennas 41 to 43 are provided in each region, and unnecessary trigger signals are canceled in that region. In this embodiment, an extra trigger signal generated in an area that is not desired to be detected is canceled using a cancel antenna in that area.

  FIG. 6 is a diagram for explaining the operation in this embodiment. 6A is a diagram corresponding to FIG. 4, FIG. 6B shows the overlapping state of the areas A to C, and FIG. 6C shows tag detection in the area B shown in FIG. 6B. FIG. 6D is a diagram showing the state of the trigger signal in the regions A to C when the tag is detected, and FIG. 6D is a trigger in the regions A to C when the tag detection is performed in the region A shown in FIG. It is a figure which shows the state of a signal. Each of the areas A to C shown in FIG. 6B corresponds to the trigger area and the cancellation area by the trigger antennas 611a to 613a and the cancellation antennas 611b to 613b in FIGS. 6B and 6C. In the figure, both antennas are displayed without being distinguished.

  With reference to FIG. 6A, the intensity of the tag detection trigger by the trigger signal is indicated by a vertical solid line, and the intensity of the cancel trigger is indicated by a vertical dotted line. As described with reference to FIG. 4, the difference between the solid line portion and the dotted line portion (the hatched portion) is a substantial tag detection signal, and the portion where this exists is the tag detection area. Here, a tag detection area is generated in an area (indicated by a2 and a3 in the figure) other than the area (indicated by a1 in the figure) where the tag should be detected. Therefore, in this embodiment, this area that should not be detected is canceled.

  Referring to FIG. 6C, a tag is detected in region B. A trigger signal and a cancel signal are output from the antennas 612a and 612b, and tag detection areas are formed (a1 to a3 in the figure). As shown in FIG. 6C, the tag detection area a1 is formed in the region B, and the tag detection area a3 is formed in the region C. Here, since it is difficult to detect a tag in the region B or the region C, a cancel signal is output from the cancel antenna 611b in the region A to cancel the tag detection area a2. Here, as shown in the figure, since the intensity of the cancel signal b1 in the area A is larger than the intensity of a2, the tag detection area a2 is canceled. The same applies to the region C.

  When region A is selected as the tag detection area, the states of the tag detection trigger and the cancel trigger are as shown in FIG.

  Next, a method for detecting the three-dimensional position of the tag using the cancel antenna will be described. FIG. 7 is a diagram showing the arrangement of trigger antennas for detecting a position on a plane in this embodiment. In this embodiment, the position in the height direction is detected using the cancel signal used in the above-described embodiment, and the planar position is also specified in the same manner as in Patent Document 1. A trigger antenna that outputs a trigger signal for detecting a planar position is provided.

  Referring to FIG. 7, on the XY plane, three trigger antennas X1, X2, and X3 are arranged in the X direction, and four trigger antennas Y1, Y2, Y3, and Y4 are arranged in the X direction in the Y direction. It arrange | positions so that it may overlap with a trigger antenna. Each trigger antenna outputs a different area ID. In this embodiment, the position on the XY plane is detected based on the area ID output in this way, and at the same time, the position in the Z-axis direction is detected by changing the value of the current flowing through each trigger antenna. Thus, the position of the RFID tag in three dimensions can be detected. The current value is changed by a current value change switch (not shown) provided in the tag position detection device 10. The tag position detecting device 10 operates as an upward position detecting means for detecting the upward position of the tag.

  In this embodiment, unlike the case of Patent Document 1, since an extra trigger signal in the Z-axis direction (height direction) can be canceled using a cancel signal from a cancel antenna (not shown), no erroneous detection occurs. .

  Next, a trigger antenna for detecting a position in the Z-axis direction will be described. 8A is a diagram showing the arrangement of the trigger antenna on the plane for detecting the position in the Z-axis direction, and FIG. 8B is a diagram showing the intensity of the trigger signal output from the trigger antenna. (C) shows the relationship between the strength of the magnetic field of the trigger signal output from the trigger antenna and the distance from the antenna coil surface.

  Referring to FIG. 8A, an antenna 51 arranged in a zigzag pattern for the vicinity and a rectangular antenna 52 for a distant object arranged so as to surround the periphery of the antenna 51 are arranged on the plane. . The intensity of the trigger signal from each antenna is as shown in FIG. 8B, and the reach distance of the output 52a from the far antenna 52 is about 2 with respect to the output 51a from the antenna 51 near the coil. It has doubled. As shown in FIG. 8C, these magnetic field intensities 51a and 52a intersect with each other at almost the center from the antenna coil surface, and each trigger signal level has a level ratio at a predetermined height. Reverse. That is, when the height from the coil surface is within a predetermined range, only the magnetic field intensity 51a from the antenna 51 is detected by the tag, and when exceeding the range, only the magnetic field intensity 52a from the antenna 52 is detected by the tag.

  Here, a case has been described in which it is determined whether or not a tag is present at two positions in the Z-axis direction. However, the present invention is not limited to this, and the antenna output intensity can be adjusted to detect a desired level. For example, a tag at an arbitrary position can be detected.

  Next, a method for detecting whether or not a tag exists only at a desired position using a plurality of planar trigger antennas will be described. FIG. 8 is a diagram showing this method. FIG. 9A is a diagram showing different trigger signals, and FIG. 9B is a diagram showing a method of detecting a specific position using these trigger signals.

  As shown in FIG. 9A, a specific range in which these trigger signals are output is detected using trigger signals 55, 56, and 57 including mutually different area IDs. Referring to FIG. 9B, it is assumed that whether or not a tag is present in region 58a is detected. In this case, a region 55a where the trigger signal 55 is output, a region 56a where the trigger signal 56 is output, and a region 57a where the trigger signal 57 is output are arranged so as to form the region 58a. The tags present in area 58a can respond with all three trigger signals. By changing the range in which the trigger signal operates and moving the region, it is possible to detect within an arbitrary range and narrow down the area.

  Next, a method for detecting the tag position at an arbitrary position in the Z-axis direction will be described. FIG. 10 is a diagram showing this method. Trigger antennas 61 and 62 for outputting trigger signals are provided at both upper and lower ends in the Z-axis direction. The intensity of the trigger signal output from the trigger antennas 61 and 62 can be adjusted. By adjusting the output 61a from the trigger antenna 61, the distance that the trigger signal reaches can be changed. Similarly, the output 62a from the trigger antenna 62 can also be adjusted. In the state shown in FIG. 9, the tag located in the region 63 in the Z-axis direction can be detected.

  This strength adjustment is performed by the tag position detection device 10 shown in FIG.

  Such a detection method is not limited to the Z-axis direction, but is the same in the XY directions. In FIG. 11, trigger antennas 65 and 66 are provided in the XY directions, and whether or not the tag is located at a predetermined position in the XY direction can be detected by adjusting the intensity of each trigger signal.

  In the above embodiment, the case where the cancel signal is generated by outputting a signal that fills the gap between the predetermined trigger signals has been described. However, as long as the cancel signal can be temporally separated from the trigger signal, the trigger signal is output. A cancel signal may be output from the antenna.

  In the above-described embodiment, the RFID tag is described as an example of the tag. However, the present invention is not limited to this, and any tag such as an active tag incorporating a battery or a passive tag can be used.

  As mentioned above, although embodiment of this invention was described with reference to drawings, this invention is not limited to the thing of embodiment shown in figure. Various modifications and variations can be made to the illustrated embodiment within the same range or equivalent range as the present invention.

It is a schematic diagram which shows the structure of the tag detection system which detects an RFID tag. It is a block diagram of a dedicated integrated circuit (IC) mounted on the RFID tag. It is a conceptual diagram which shows the area | region limitation operation | movement of the high frequency magnetic field by three trigger antennas. It is a figure for demonstrating a cancellation trigger signal. It is a figure which shows area ID data and cancellation data. It is a figure which shows the other example of area ID data and cancellation data. It is a figure which shows arrangement | positioning of the trigger antenna for detecting the plane position in a three-dimensional position detection system. It is a figure which shows arrangement | positioning of the trigger antenna for detecting a different position in a Z-axis direction, and an output example. It is a figure which shows the example of arrangement | positioning of a trigger antenna in the case of detecting whether a tag exists in the specific position on XY plane. It is a figure which shows the other method of detecting whether a tag exists in the arbitrary positions of a Z-axis direction. It is a figure which shows the example of arrangement | positioning of the trigger antenna for detecting whether a tag exists in the predetermined position on XY plane. It is a figure for demonstrating the problem in the method of detecting the three-dimensional position of the conventional tag.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Tag detection apparatus, 11 Control part, 12 Trigger signal transmission part, 13 Reception part, 14 Cancel signal transmission part, 15 Display part, 16 Trigger antenna, 17 Cancel antenna, 20 Tag

Claims (4)

Trigger signal output means provided on a plane and outputting a predetermined trigger signal;
Cancel signal output means for outputting a cancel signal for canceling a part of the trigger signal output by the trigger signal output means,
An upward position detection means for detecting an upward position of the tag responding to the trigger signal using the trigger signal partially canceled by the cancellation signal output means,
The trigger signal output means is a trigger antenna provided on the plane and surrounding a predetermined range;
The cancellation means is a cancellation antenna that is provided in the vicinity of the trigger antenna and outputs the cancellation signal.
Wherein the trigger antenna and the cancellation luer containers placed close to each other,
By adjusting the output intensity of the trigger antenna and the cancel antenna, the upward position detection means detects the tag at an arbitrary position in the upward direction of the tag in response to the trigger signal,
The tag three-dimensional position detection system, wherein the cancel signal data and the trigger signal data have a complement relationship with each other . 2. The tag three-dimensional position detection system according to claim 1, wherein the trigger antenna includes a plurality of antennas that are spaced apart from each other in the first direction on the plane and that output different trigger signals. 3. The tag three-dimensional according to claim 2 , wherein the trigger antenna includes a plurality of antennas that are spaced apart from each other in a second direction intersecting the first direction on a plane and that output different trigger signals. Position detection system. The cancel signal output means includes a plurality of trigger signal output means for outputting different trigger signals,
The upper direction position detecting means, by detecting a tag in response to signals from the plurality of trigger signal output means detects the direction of the top position of the tag in response to said trigger signal, of claims 1 to 3 A three-dimensional position detection system for a tag according to any one of the above.

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