JP2007183286A - System for measuring flow line - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a system for measuring a flow line capable of tracking a position of a transmitter, capable of facilitating arrangement design for a receiver, and capable of reducing labors and times of execution work for the receiver, compared with those in conventional configuration. <P>SOLUTION: The transmitter 1 includes a compressional wave transmitting part 11 mounted on a detection object and for transmitting intermittently a compressional wave, and an identification data transmitting part 12 for transmitting an intrinsic identification data by a wireless signal using an infrared ray as a transmission medium. The receiver 2 includes a compressional wave receiving part 21 for receiving the compressional wave and for outputting a reception wave output including information of an arrival direction of the compressional wave, and an identification data receiving part 22 for receiving the wireless signal including the identification data. A moved position of the detection object is tracked based on the detection of the position of a transmitter 1 by the receiver 2. A period of receiving the compressional wave by the compressional wave receiving part 21 is limited within a predetermined receivable time set after the identification data is received, in the receiver 2. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a flow line measurement system that tracks the position of a detection target using an ultrasonic wave that periodically repeats a pressure change of a medium or a so-called pressure wave in which the pressure change of the medium is single. It is.

  Conventionally, a transmitting device (ultrasonic transmitter) that transmits ultrasonic waves to a moving object that is a detection target of position detection is provided, and at least three receiving devices (for each predetermined area on a ceiling surface in a building) ( The ultrasonic wave from the transmission device is received by the ultrasonic receiver), and the position calculating unit (calculation processing means) uses the time until the ultrasonic wave transmitted from the transmission device is received by the reception device. There has been proposed a position detection system for obtaining the position (see, for example, Patent Document 1).

  In the position detection system described in Patent Document 1, a permission signal using infrared as a transmission medium is transmitted from a reception device to a transmission device, and the transmission device transmits an ultrasonic wave when the permission signal is received. Therefore, the distance to the transmitter can be calculated by measuring the time from receiving the permission signal to receiving the ultrasonic wave in the receiver, and the distance to the transmitter in the three receivers Therefore, the position of the transmitting device can be specified based on the known positions of the three receiving devices.

  In addition, a configuration is described as a conventional configuration in which the transmission device sequentially transmits ultrasonic waves based on division times set in advance in a time division manner, thereby specifying the transmission device and calculating the position of the moving body. In Patent Literature 1, in order to solve the problem that it takes a long time to calculate the position of each transmitting device when the number of transmitting devices increases when the receiving time is determined for each transmitting device. A configuration is adopted in which the start of the ultrasonic transmission / reception period is designated from the apparatus to the receiving apparatus.

These configurations are preconditions for identifying ultrasonic waves transmitted from a plurality of transmission devices in the reception device, and even if any configuration includes a plurality of transmission devices, The position can be obtained for each transmission device.
JP 2003-279640 A

  By the way, when the prior art described in Patent Document 1 is adopted, there is a problem that it takes time to measure the position of each transmitting device when the number of transmitting devices is large. According to the technology, since the position detection switch attached to the transmission apparatus must be operated, the position of the transmission apparatus cannot be tracked when the transmission apparatus changes its position every moment.

  Furthermore, in the technique described in Patent Document 1, the position of the transmitting apparatus cannot be obtained unless three receiving apparatuses are used, and the position of the transmitting apparatus is only within a range where the detection areas of the three receiving apparatuses overlap. Therefore, there is a problem that it is difficult to design the arrangement of the receiving apparatus for setting the target detection area, and that the work for constructing the receiving apparatus is troublesome.

  The present invention has been made in view of the above-described reasons, and the object thereof is to promptly determine the position for each transmitting apparatus without performing a special operation even when a plurality of transmitting apparatuses exist. Thus, it is possible to provide a flow line measurement system that enables tracking of the position of a transmission device, and that facilitates layout design of the reception device and reduces the time and effort of construction of the reception device as compared with the conventional configuration. is there.

  According to the first aspect of the present invention, there is provided a transmission device that is mounted on a detection target for position detection and that intermittently transmits at least a sparse / dense wave, and a relative that a detection target exists by receiving a sparse / dense wave transmitted from the detection target. And a receiving device that detects a specific direction and distance, and a flow line measurement system that tracks the position of the detection target moved by detecting the position of the transmitting device by the receiving device. The reception device receives and receives the sparse / dense wave transmitted from the sparse / dense wave transmission unit, and an identification data transmission unit that transmits unique identification data using a wireless signal. A sparse / dense wave received by a sparse / dense wave receiving unit composed of an array sensor in which a plurality of receiving elements for converting a sparse / dense dense wave into a received signal, which is an electric signal, and a sparse / dense wave receiving unit. Time difference and location of receiving elements Based on the position calculation unit for obtaining the direction in which the detection target exists with respect to the dense wave receiving unit, the identification data receiving unit for receiving the identification data from the identification data transmitting unit, and the dense wave receiving unit And a reception time limiter that limits a reception period within a predetermined reception-enabled time set after the identification data is received.

  According to this configuration, since the time for receiving the density wave from the transmission device in the reception device is limited to the predetermined reception time set after receiving the identification data in the reception device, the external density The possibility of receiving waves can be reduced. In addition, in a usage where the detection target moves relative to the reception device and the detection target enters and exits the reception area of the dense wave in the reception device, each detection target has a plurality of detection targets. There is a possibility that the position of the detection target cannot be individually detected due to collision of the dense waves from the transmission device mounted on the detection target, but each transmission device can be detected by transmitting unique identification data from the transmission device. In addition to being able to identify, by limiting the time to receive the sparse / acoustic wave for each transmitter, the possibility of sparse / interference interference from each transmitter can be reduced and the position of each detection target can be detected individually. Get higher. Here, in this configuration, it is not possible to avoid the interference of sparse and close waves from a plurality of transmission devices. However, since the transmission device does not require a configuration for avoiding interference or collision, a special configuration is required in the transmission device. The position of each transmission device can be quickly obtained without processing or operation, and the position of the transmission device can be tracked. Moreover, the direction in which the detection target exists is based on the time difference between the reception times of the dense waves by the receiving elements provided in the array sensor and the arrangement position of each receiving element using the dense wave receiving unit using the array sensor. In other words, since the direction of arrival of the dense wave from the transmission device is detected, the position of the transmission device can be known without using three reception devices. As a result, construction is easy and the detection area can be easily set. That is, it can be provided at a low cost. Here, it is desirable to use an ultrasonic intermittent wave (ultrasonic burst wave) or a single dense wave as the dense wave transmitted from the dense wave transmission unit.

  According to a second aspect of the present invention, in the first aspect of the invention, the reception time limit unit starts a reception possible time after a predetermined delay time from the time when the identification data reception unit receives the identification data, and the delay The time is set to a time required for the dense wave to reach from the transmission device to the reception device at the minimum allowable distance between the detection target and the reception device.

  This configuration is effective when a wireless signal for transmitting identification data uses a transmission medium (infrared rays or radio waves) that can substantially ignore the time from the transmission device to the reception device, and transmits the identification data. In a time when there is no possibility of receiving the sparse wave from the transmitter, the sparse wave from a plurality of transmitters can be suppressed by not accepting the sparse wave from the transmitter.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the identification data transmission unit intermittently transmits the identification data at a constant time interval, and the transmission device transmits the identification data. Means is provided for randomly setting the time interval using a random number generated in response to an instruction to set the interval.

  According to this configuration, since the time interval for transmitting the identification data is irregularly set by a random number, there is always a period in which the identification data can be received at different timings in the reception device even when there are a plurality of transmission devices. As a result, it becomes possible to receive the identification data for each of the plurality of transmitting apparatuses and detect the position of the transmitting apparatus.

  According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, the transmission pattern of the dense wave transmitted from the dense wave transmission unit is used as identification data transmitted from the identification data transmission unit. An identification pattern generation unit to be associated, and when the position calculation unit receives the density pattern received by the density wave reception unit corresponding to the identification data received by the identification data reception unit A direction in which the detection target exists is obtained using a wave.

  According to this configuration, the transmission / reception pattern of the sparse / dense wave is associated with the identification data, and the receiving device obtains the direction of the detection target from the sparse / dense wave having the reception pattern corresponding to the identification data. It is possible to identify whether the wave is transmitted from the transmission device.

  According to a fifth aspect of the present invention, in the invention according to any one of the first to third aspects, the identification data transmitting unit uses a dense wave transmitted from the dense wave transmitting unit as a transmission medium and fixes the identification data. It is represented by a long bit string, and each bit value is associated with a time interval for transmitting a dense wave.

  According to this configuration, since the dense wave used for detecting the position of the detection target is also used for transmitting the identification data, it is not necessary to provide a separate configuration for transmitting and receiving the identification data, and the interference of the dense wave is suppressed. The configuration can be realized at a relatively low cost.

  According to the configuration of the present invention, the reception time of the dense wave from the transmission device in the reception device is limited to a predetermined reception time set after receiving the identification data in the reception device. There is an advantage that it is possible to reduce the possibility of receiving the dense wave. In this configuration, interference of sparse and close waves from a plurality of transmission devices cannot be avoided, but a configuration for avoiding interference or collision is not necessary in the transmission device, so that special processing and operation in the transmission device are not required. There is an advantage that the position of each transmitting apparatus can be quickly obtained without performing tracking, and the position of the transmitting apparatus can be tracked. In addition, a dense wave receiving unit using an array sensor is used, and the dense wave from the transmitting device is based on the time difference between the reception times of the dense waves by the receiving elements provided in the array sensor and the arrangement position of each receiving element. Since the arrival direction is detected, the position of the transmitting apparatus can be known without using three receiving apparatuses.

(Embodiment 1)
In the present embodiment, as shown in FIG. 2, a moving body (for example, a shopping cart) that moves on the floor surface FL in a building is set as a detection target Ob for position detection, and the movement for tracking the position where the detection target Ob has moved is detected. A line measurement system is illustrated. In order to track the position of the detection target Ob, the transmitting device 1 that transmits the dense wave is mounted on the upper surface of the detection target Ob, and the dense wave is received at a fixed position of the ceiling surface CL above the floor surface FL. A wave receiving device 2 is installed. Therefore, the receiving device 2 is arranged at a known position. In the present embodiment, a pressure wave in which a pressure change of the medium (air) occurs once as a dense wave is used.

  As shown in FIG. 1, the transmission device 1 includes a dense wave transmission unit 11 that transmits a dense wave, and an identification data transmission unit 12 that transmits a wireless signal using infrared as a transmission medium. The sparse / dense wave transmission unit 11 and the identification data transmission unit 12 operate in response to instructions from the control unit 10 via the drivers 13 and 14, respectively. The control unit 10 includes a one-chip microcomputer and includes a CPU, RAM, ROM, and serial communication interface. The sparse / dense wave transmission unit 11 intermittently transmits the sparse / dense wave, and the identification data transmission unit 12 transmits a wireless signal including identification data. The identification data is set in the control unit 10, and unique identification data is set for each transmission device 1. The control unit 10 controls the transmission timing of the sparse / dense wave and the transmission timing of the wireless signal. Specifically, a sparse wave is transmitted simultaneously with the transmission of a wireless signal including identification data (actually, the one-chip microcomputer is between the time when the wireless signal is transmitted and the time when the sparse wave is transmitted. In other words, the wireless signal and the sparse / dense wave are intermittently output at a predetermined output interval. The functions of the transmission device 1 described above are realized by mounting an appropriate program on the one-chip microcomputer constituting the control unit 10.

  The receiver 2 includes a sparse wave receiver 21 that receives the sparse wave transmitted from the sparse wave transmitter 11 provided in the transmitter 1, and the sparse wave receiver 21 receives the sparse wave. A received signal that is an electrical signal is output. That is, the dense wave receiving unit 21 converts the dense wave into a received signal. The receiving device 2 is also provided with an identification data receiving unit 22 that receives a wireless signal transmitted from the identification data transmitting unit 12 provided in the transmitting device 1. The identification data receiving unit 22 removes the carrier from the wireless signal and extracts the identification data. The identification data composed of the pulse train extracted by the identification data receiving unit 22 is input to the control unit 20, and the transmission device 1 that has transmitted the identification data is recognized by the control unit 20. The control unit 20 includes a microcomputer as a main component, and includes a CPU, a RAM, a ROM, and a serial communication interface. Further, an output interface is added as an output unit 26 separately. The output unit 26 can employ a serial interface with specifications such as TIA / EIA-232-E and USB, and a parallel interface with specifications such as SCSI. The detection result can be used.

  The dense wave receiving unit 21 is an array sensor in which a plurality of receiving elements are arranged, and the control unit 20 is based on the time difference between the receiving times of the dense waves by the receiving elements and the arrangement positions of the receiving elements. Thus, the arrival direction of the dense wave, that is, the direction in which the detection object Ob exists is obtained. The direction to be obtained here is a relative direction with respect to the dense wave receiving unit 21, but since the arrangement of the receiving device 2 is known, the arrival direction of the dense wave in the absolute coordinate system for specifying the arrangement of the receiving device 2 is obtained. be able to.

  As described above, in order to obtain the arrival direction of the dense wave, information including the time difference between the reception times at the wave receiving elements that have received the dense wave is required. The wave signal is converted into received data that is a digital signal by the A / D converter 23 and then stored in the data storage unit 24 that temporarily stores the output corresponding to each receiving element. The sparse / dense wave receiving unit 21 always receives incoming sparse / dense waves, but the timing control unit 25 controls the operation timing of the A / D conversion unit 23 and the data storage unit 24 according to instructions from the control unit 20. . The timing control unit 25 is configured using CPLD (Complex Programmable Logic Device) or FPGA (Field Programmable Gate Array), and generates an enable signal for controlling the operation timing of the A / D conversion unit 23 and the data storage unit 24. In addition, an address for designating a storage area of the data storage unit 24 is generated.

  In the control unit 20, when the identification data input from the identification data receiving unit 22 through the serial communication interface is identification data within a pre-registered range, the control unit 20 instructs the timing control unit 25 to receive the reception signal corresponding to the received signal. The standby state for storing the wave data in the data storage unit 24 is entered. This standby state is limited to a wave reception time set after receiving a wireless signal including identification data. In other words, the dense wave received by the dense wave receiving unit 21 outside the reception possible time is not converted into received data and is not stored in the data storage unit 24. In other words, a sparse / dense wave is received only within the reception time. In other words, the control unit 20 and the timing control unit 25 function as a reception time limit unit.

  The wave reception time is a fixed time, and when the dense wave receiving unit 21 receives the dense wave within the wave reception possible time after the wave reception possible time is started, each wave receiving element receives the density wave. The received data corresponding to the received signal is stored in the data storage unit 24 in a form including the time information. In addition, when the wave reception possible time ends, the dense wave received thereafter becomes invalid.

  The received data stored in the data storage unit 24 is read into the control unit 20 after the reception-enabled time has ended, and adjacent reception signals are obtained in order to obtain a time corresponding to the time difference between reception times at each reception element. The received data corresponding to the element is shifted by a predetermined time in the time axis direction and added.

This process will be briefly described. Now, it is assumed that the receiving elements 40 are arranged one-dimensionally at equal intervals on the same plane as shown in FIG. 3 (in practice, they are arranged two-dimensionally). ). When the angle of the wavefront of the ultrasonic wave with respect to the surface on which the wave receiving elements 40 are arranged is θ ₀ , the arrival direction of the dense wave is also θ ₀ . If the speed of sound is c and the arrangement pitch (intermediate distance) of the receiving elements 40 is L, the time difference ΔT ₀ when the wavefront of the dense wave whose arrival direction is θ ₀ reaches the adjacent receiving element 40 is , ΔT ₀ = L · sin θ ₀ / c. That is, θ ₀ = sin ⁻¹ (ΔT ₀ · c / L), and the arrival direction θ ₀ can be obtained by obtaining the time difference ΔT ₀ .

Based on the above relationship, if the received signal corresponding to the sparse / dense wave received by each receiving element 40 is delayed by the time difference ΔT ₀ corresponding to the arrival direction θ ₀ , the position of the received signal matches in the time axis direction. You can see that For example, the received signals as shown in FIGS. 4A to 4C are output from three adjacent receiving elements 40, and the received signals output from the adjacent receiving elements 40 have a time difference ΔT ₀ . Suppose you are. In this case, the reception signals obtained from the adjacent reception elements 40 are delayed by ΔT _{0 from} each other by appropriate delay means. That is, when the received signal in FIG. 4C is delayed by 2ΔT ₀ and the received signal in FIG. 4B is delayed by ΔT ₀ , both received signals in FIG. It matches the position of the received signal. If the received signals that are the outputs of the receiving elements 40 have the same position in the time axis direction, when these received signals are added, the addition result has a large amplitude. In other words, if the amplitude of the addition result is large, it can be said that the arrival direction θ ₀ of the density wave corresponds to the delay time ΔT ₀ .

In the present embodiment, the received signal is not shifted in the time axis direction, but the received data is shifted in the time axis direction. However, for the purpose of calculating the arrival direction θ ₀ , the difference is Absent. Therefore, the control unit 20 adds the delay time to the received data stored in the data storage unit 24 after applying a plurality of preset delay times and delays the addition result. Ask for time. Since this delay time corresponds to the time difference ΔT ₀ , the arrival direction of the dense wave can be immediately obtained by associating the arrival direction θ ₀ with the delay time in advance. The delay time is set so that, for example, the arrival direction can be detected in increments of 5 degrees. As described above, the process of adding the received data after shifting the received data in the time axis direction is called a delay addition process. The delay addition process is realized by a program set in the control unit 20.

  As described above, when the receiving device 2 receives the wireless signal from the transmitting device 1 and confirms that the wireless signal includes identification data within the range registered in the control unit 20, the reception time limit is limited. The received signal is waited for in the receiver, and the arrival direction of the sparse / dense wave is calculated using only the sparse / dense wave received within the reception time.

  Here, as described above, there is a known constant time delay between the transmission of the wireless signal and the transmission of the sparse / dense wave, but the transmission of the wireless signal from the identification data transmitting unit 12 and the identification data receiving unit 22 Therefore, the time difference between the reception time of the wireless signal at the identification data receiving unit 22 and the reception time of the dense wave at the dense wave receiving unit 21 is known. If the calculation is performed in consideration of the time delay, it can be regarded as a time during which the dense wave propagates through the medium. Therefore, it is possible to know the relative distance of the transmission device 1 with respect to the reception device 2 based on the time from reception of the wireless signal to reception of the dense wave. That is, since the direction and distance of the transmission device 1 can be known, the reception device 2 can obtain the three-dimensional position of the transmission device 1. The operation of the control unit 20 described above is realized by installing an appropriate program in the microcomputer.

  An operation example of this embodiment is shown in FIG. Now, as shown in FIG. 2, it is assumed that there are two detection targets Ob in a detection area that can receive a sparse / dense wave from the transmission apparatus 1 and receive a wireless signal. In order to distinguish between the two detection targets Ob, the left detection target in FIG. 2 is referred to as Ob1, and the right detection target is referred to as Ob2. It is assumed that the distances between the detection targets Ob1 and Ob2 and the receiving device 2 are substantially equal.

  Since each transmission device 1 intermittently outputs a dense wave and a wireless signal, for example, as shown in FIG. 5A, the wireless signal transmitted from the transmission device 1 provided in the detection target Ob1 is identified. Assuming that the data is detected at the time t1 in the receiving device 2, the time limit of the wave reception possible time Tp is started from the time t1 as shown in FIG. 5B. When the receiving device 2 receives a sparse / dense wave during the time limit of the receivable time Tp, it is determined that the sparse / dense wave is a sparse / dense wave from the transmitting device 1 provided in the detection target Ob1 and the direction in which the detection target Ob1 exists. Is calculated. That is, the arrival direction of the sparse / dense wave received during the wave reception possible time Tp is regarded as the direction in which the transmission device 1 indicated by the identification data exists.

  For example, as shown in FIG. 5A, the wireless signal transmitted at the time t2 during the time limit of the wave reception possible time Tp is ignored, and the wave reception possible time Tp from the time t1 as shown in FIG. 5C. If only the dense wave W1 arriving between the two is extracted, the influence of the dense wave W2 from the transmission device 1 mounted on the detection target Ob2 is removed, and only the dense wave W1 from the transmission device 1 mounted on the detection target Ob1 is removed. It becomes possible to extract.

  Depending on the positional relationship between the detection targets Ob1 and Ob2, the reception device 2 may receive the dense waves W1 and W2 from the two transmission devices 1 during the wave reception possible time Tp. Therefore, the arrival directions of the dense waves W1, W2 are not calculated until the dense waves W1, W2 from only one transmitter 1 are received.

  As described above, when the identification data obtained by receiving the wireless signal is used as a trigger to start the time limit of the receivable time Tp, and when the dense waves W1 and W2 are received during the time limit of the receivable time Tp In addition, the sparse / dense waves W1 and W2 are determined to be sparse / dense waves from the transmission device 1 corresponding to the identification data, and the arrival directions of the sparse / dense waves W1 and W2 are calculated as directions in which the transmission device 1 exists. With this operation, it is possible to reduce the possibility of erroneously recognizing the direction in which the transmitter 1 is present due to interference between the dense waves W1 and W2.

  The reception possible time Tp does not need to be timed immediately after receiving the wireless signal. When the delay time corresponding to the minimum allowable distance between the transmission device 1 and the reception device 2 is known, the reception possible time Tp is from the reception of the wireless signal. You may start the time limit of the wave reception possible time Tp after delay time passes. That is, since the wireless signal uses light as a transmission medium, a time difference from when the wireless signal is transmitted from the transmission device 1 to when it is received by the reception device 2 can be ignored. The minimum time required to reach the receiving device 2 corresponds to the time required for the sparse wave to propagate the minimum allowable distance between the transmitting device 1 and the receiving device 2.

  That is, after the wireless signal is received by the receiving device 2, the dense wave does not arrive before the minimum time, so this minimum time is set as the delay time, and the reception is delayed by the delay time from the reception of the wireless signal. Even if the time limit time of the possible time Tp is started, the arrival direction of the sparse / dense wave can be detected. Here, the identification data cannot be confirmed when the wireless signal is received, but the confirmation time from the reception of the wireless signal until the identification data is confirmed is known, so the delay time from the confirmation time of the identification data is known. If the delay time is set to be short by a known confirmation time at that time, it is equivalent to measuring the delay time from the reception time of the wireless signal.

  The length of the receivable time Tp is defined by the longest distance of the transmission apparatus 1 that attempts to detect the position. That is, the longest distance at which position detection is performed by the receiving device 2 is defined, and the time required for the sparse / dense wave to propagate through this distance is determined from the time when the receiving device 2 receives the wireless signal until the wave reception possible time Tp ends. Set the time.

  When the wave reception possible time Tp is set as described above, the sparse wave that arrives in a period during which there is no possibility of wave reception in the reception device 2 is invalid and is not used for position detection, and the position of the transmission device 1 is changed. The possibility of erroneous detection can be reduced.

  For example, as shown in FIG. 6A, it is assumed that a wireless signal is received and identification data is confirmed at time t1. Here, it is assumed that two dense waves Wx and W1 arrive at the receiving device 2 after time t1. As shown in FIG. 6 (b), the time Tp that can be received starts at the time t2 after the delay time Td has elapsed from the reception of the wireless signal, and then the time corresponding to the target longest distance has elapsed. The time limit ends at time t3. The above-described dense wave Wx arrives before time t2, and becomes invalid because the point of arrival deviates from the reception time Tp, and the dense wave Wx is not extracted as shown in FIG. 6C. . On the other hand, since the dense wave W1 arrives between time t2 and time t3, the arrival time is included in the wave reception possible time Tp and is used for position detection.

  In the above-described configuration example, it is assumed that the transmission intervals of the wireless signal and the sparse / dense wave are constant and the time intervals of transmission in different transmission apparatuses 1 are equal. In this case, in the plurality of transmission apparatuses 1 If the timing for transmitting the wireless signal first matches, then the timing for transmitting the wireless signal always matches, and the receiving device 2 cannot identify the transmitting device 1 from which the wireless signal is transmitted.

  Therefore, the transmitter 1 is provided with a function for automatically setting a time interval for transmitting a wireless signal (that is, identification data). This function is activated when a time interval setting is requested. First, a random number is generated, and then the time interval for transmitting the identification data is set using the generated random number. The time interval setting request may be made only when the transmitter 1 is turned on, but an appropriate operation unit such as a push button switch may be provided so that the time interval setting request can be made at an arbitrary timing.

  By adopting this configuration, the time interval for transmitting the wireless signal can be made different for each transmitter 1. Therefore, even when the wireless signal from the transmitting device 1 is transmitted once and the receiving device 2 cannot recognize the identification data by colliding with the wireless signal from the other transmitting device 1, the wireless signal is transmitted a plurality of times. During this time, the wireless signal can be transmitted at a timing at which a collision with a wireless signal from another transmitter 1 can be avoided.

  By the way, although the ultrasonic transducer which consists of a piezoelectric element may be used for the transmission element which comprises the dense wave transmission part 11 in the transmitter 1, a piezoelectric element generally has a sharpness (Q value). Since it exceeds 100, the reverberation time is relatively long, and considering the reverberation time, the time interval for transmitting the dense wave becomes long. That is, when the detection target on which the transmission device 1 is mounted is a moving body, the position of the moving body cannot be measured finely.

  Therefore, it is desirable to use the transmission element 30 having the structure shown in FIG. In this transmission element 30, a thermal insulating layer 32 made of a porous silicon layer is formed on one surface (upper surface in FIG. 7) side of a support substrate 31 made of a single crystal p-type silicon substrate. A heating element layer 33 made of a metal thin film (for example, a tungsten thin film) is formed, and a pair of electrode pads 34 electrically connected to the heating element layer 33 is formed on the one surface side of the support substrate 31. Yes. The planar shape of the support substrate 31 is rectangular, and the planar shape of the heat insulating layer 32 and the heating element layer 33 is also rectangular.

  The wave transmitting element 30 is of a thermal excitation type, and the heating element layer 33 is energized so that a temperature change occurs in the heating element layer 33 and the medium in contact with the heating element layer 33 is encouraged to expand and contract. Generate a wave. That is, by energizing between the electrode pads 34 at both ends of the heating element layer 33 to cause a temperature change in the heating element layer 33, a temperature change is caused in the air that is in contact with the heating element layer 33. The air in contact with the heating element layer 33 expands when the temperature of the heating element layer 33 rises and contracts when the temperature of the heating element layer 33 decreases. It is possible to generate a dense wave.

  Since a wave transmitting element made of a piezoelectric element has a high sharpness (Q value), even if a sparse wave is generated instantaneously, the piezoelectric element is also shown in FIG. 8B even after the driving of the piezoelectric element is stopped. Thus, reverberation continues due to resonance. On the other hand, the thermally excited wave transmitting element 30 shown in FIG. 7 has a small sharpness and does not substantially have a resonance frequency. In the thermal excitation type wave transmitting element 30, as described above, a sparse wave is generated in accordance with a temperature change of the heating element layer 33 accompanying energization to the heating element layer 33 via the pair of electrode pads 34.

  That is, when the waveform of the drive voltage or drive current applied to the heating element layer 33 has a sine wave shape, a dense wave having a frequency twice that of the sine waveform can be generated. Therefore, if the waveform of the drive voltage applied to the electrode pad 34 is an isolated wave corresponding to a half cycle of a sine wave, a dense wave corresponding to one cycle of the sine waveform as shown in FIG. Can do. In addition, the reverberation time is very short because the thermal excitation type transmitting element 30 does not substantially have a resonance frequency. In addition, since the piezoelectric element has a specific resonance frequency, the frequency range of the density wave that can be generated is narrow. However, since the thermal excitation type transmission element 30 does not substantially have the resonance frequency, the frequency range of the density wave that can be generated. Becomes widespread. In addition, if the waveform of the drive voltage or drive current is an isolated wave, a sparse / dense wave of about one cycle can be generated as shown in FIG.

  The above-described thermally excited wave transmitting element 30 uses a p-type silicon substrate as the support substrate 31, and the thermal insulating layer 32 is a porous silicon layer having a porosity of 60 to 80% (preferably about 70%). It is constituted by. This is because if the porosity is less than 60%, the heat insulating effect is reduced, and if the porosity exceeds 80%, the structure becomes brittle. The thermal insulating layer 32 can be formed by anodizing a part of a silicon substrate used as the support substrate 31 in an electrolytic solution made of a mixed solution of hydrogen fluoride aqueous solution and ethanol. Here, by appropriately setting conditions for anodizing treatment (for example, current density, energization time, etc.), the porosity and thickness of the porous silicon layer to be the heat insulating layer 32 can be set to desired values, respectively. .

It is known that the porous silicon layer has a lower thermal conductivity and heat capacity as the porosity increases. For example, a single crystal silicon substrate having a thermal conductivity of 148 W / (m · K) and a heat capacity of 1.63 × 106 J / (m ³ · K) is anodized to form a porous silicon layer having a porosity of 60%. When formed, this porous silicon layer has a thermal conductivity of 1 W / (m · K) and a heat capacity of 0.7 × 10 6 J / (m ³ · K). In the present embodiment, as described above, the heat insulating layer 32 is formed of a porous silicon layer having a porosity of approximately 70%, and the heat conductivity of the heat insulating layer 32 is 0.12 W / (m · K), The heat capacity is 0.5 × 10 6 J / (m ³ · K).

  The thermal insulation layer 32 is made smaller than the support substrate 31 in terms of thermal conductivity and heat capacity, and the product of thermal conductivity and thermal capacity is also made sufficiently smaller than the support substrate 31 in terms of the product of thermal conductivity and thermal capacity. The temperature change of the heat generating body layer 33 can be efficiently transmitted to the air, and heat can be efficiently exchanged between the heat generating body layer 33 and the air. In addition, since the support substrate 31 efficiently receives the heat from the heat insulating layer 32, the heat of the heat insulating layer 32 can be released and the heat from the heating element layer 33 is prevented from being accumulated in the heat insulating layer 32. Can do.

The heating element layer 33 is made of tungsten, which is a kind of refractory metal, and has a thermal conductivity of 174 W / (m · K) and a heat capacity of 2.5 × 10 6 J / (m ³ · K). . The material of the heating element layer 33 is not limited to tungsten, and for example, tantalum, molybdenum, iridium, or the like may be employed.

  In the thermal excitation type wave transmitting element 30 described above, the thickness of the support substrate 31 is 525 μm, the thickness of the thermal insulating layer 32 is 10 μm, the thickness of the heating element layer 33 is 50 nm, and the thickness of each electrode pad 34 is 0. .5 μm. However, these thicknesses are only examples, and are not intended to be particularly limited. Further, Si is adopted as the material of the support substrate 31, but the material of the support substrate 31 is not limited to Si, and for example, it can be made porous by anodizing treatment of Ge, SiC, GaP, GaAs, InP or the like. Other semiconductor materials may be used.

  By the way, the wave receiving element 40 used for the dense wave receiving unit 21 of the receiving device 2 receives the dense wave and converts the received dense wave into a received signal that is an electric signal. The wave section 21 is configured by arranging a plurality of receiving elements 40 on a single substrate (not shown). Here, it is assumed that an array sensor in which the wave receiving elements 40 are two-dimensionally arranged is configured. In the array sensor, the center-to-center distance (arrangement pitch) of the wave receiving elements 40 is set to about the wavelength of the density wave generated from the density wave transmission unit 11 (for example, about 0.5 to 5 times the wavelength of the density wave). It is desirable. This is because if the wavelength is smaller than 0.5 times the wavelength of the dense wave, the time difference between the times when the wave front of the dense wave reaches each of the adjacent receiving elements 40 becomes small, making it difficult to detect the time difference. Although a piezoelectric element can be used as the wave receiving element 40, a configuration with less reverberation is desirable as in the case of the dense wave transmission unit 11. Therefore, it is desirable to use a capacitive wave receiving element 40 that converts the pressure (sound pressure) of the density wave into a change in capacitance.

  This type of receiving element 40 has a configuration shown in FIG. A wave receiving element 40 shown in the figure is formed by a micromachining technique and has a rectangular frame-shaped frame 41 formed by providing a silicon substrate with a window hole 41a penetrating in the thickness direction, and a window hole on one surface side of the frame 41. And a cantilever type pressure receiving plate 42 which is fixed to one of the four sides surrounding 41a and is arranged to cover the window hole 41a. A silicon oxide film 46 is laminated on the one surface of the frame 41 via a thermal oxide film 45, and the surface of the silicon oxide film 46 is covered with a silicon nitride film 47. One end of the pressure receiving plate 42 is fixed to the frame 41 via the thermal oxide film 45, and the other end of the pressure receiving plate 42 faces the silicon oxide film 46 in the thickness direction of the silicon substrate. A fixed electrode 43a made of a metal thin film (for example, a chromium film) is formed on a surface of the silicon oxide film 46 facing the other end of the pressure receiving plate 42, and the other end of the pressure receiving plate 42 faces the fixed electrode 43a. A movable electrode 43b made of a metal thin film (for example, a chromium film) is formed on the back side of the surface facing the fixed electrode 43a. A silicon nitride film 48 is formed on the other surface of the frame 41. Here, the pressure receiving plate 42 is formed of a silicon nitride film formed in a separate process from the silicon nitride films 47 and 48.

  In the capacitance type wave receiving element 40 shown in FIG. 9, when the pressure (sound pressure) of the dense wave acts on the pressure receiving plate 42, the distance between the fixed electrode 43a and the movable electrode 43b changes according to the pressure of the dense wave. Therefore, the pressure of the dense wave can be detected by detecting the capacitance between the fixed electrode 43a and the movable electrode 43b. Therefore, if a DC bias voltage is applied between the fixed electrode 43a and the movable electrode 43b, a voltage change corresponding to the pressure of the dense wave occurs between the fixed electrode 43a and the movable electrode 43b. Sound pressure can be converted into an electrical signal. Since this type of capacitive wave receiving element 40 has a sharpness smaller than that of the piezoelectric element, it is possible to widen the frequency bandwidth of the dense wave that can be received compared to the case where the piezoelectric element is used.

  The wave receiving element 40 is not limited to the structure shown in FIG. 9. For example, a movable electrode formed by processing a silicon substrate or the like by a micromachining technique or the like and having a diaphragm portion that receives the pressure of a dense wave, and a diaphragm You may employ | adopt the structure which detects the electrostatic capacitance between the fixed electrodes which consist of a backplate part which opposes a part. In this configuration, a spacer portion made of an insulating film that defines the gap length between the diaphragm portion and the back plate portion when the pressure of the dense wave is not applied is provided, and a plurality of exhaust holes are provided in the back plate portion. To do.

  The sharpness (Q value) of the thermal excitation type transmitting element 30 shown in FIG. 7 is about 1, and the sharpness of the capacitive type receiving element 40 shown in FIG. However, the sharpness is significantly smaller than that of the piezoelectric element. Therefore, as compared with the case where piezoelectric elements are used for the transmitting and receiving elements, the ratio of the reverberation component included in the dense wave transmitted from the dense wave transmitting unit 11 is reduced, and the density of the dense wave receiving unit 21 is reduced. The ratio of the reverberation component contained in the output received signal is reduced. In other words, the transmission interval of the sparse / dense wave can be shortened during transmission, and the received signal corresponding to the sparse / dense wave can be separated so as not to overlap even when the sparse / dense wave is received at a short time interval during reception. it can. Note that the sharpness (Q value) of each of the transmitting element 30 and the receiving element 40 is preferably 10 or less, and more preferably 5 or less.

(Embodiment 2)
In the present embodiment, as shown in FIG. 10, an identification pattern generation unit 15 that adds a transmission pattern to the dense wave transmitted from the dense wave transmission unit 11 in the transmission device 1 is added. The identification pattern generation unit 15 gives a transmission pattern to the density wave by at least one of the generation timing and the number of generation times of the density wave. For example, when identification data is transmitted once, a plurality of dense waves are transmitted, and the transmission pattern of the dense waves is changed according to the number of the dense data. Alternatively, when the identification data is transmitted once, the transmission pattern of the sparse / dense wave is changed by transmitting a plurality of sparse / dense waves and changing the time interval for transmitting the sparse / dense wave.

  Now, it is assumed that the identification data transmitted by the wireless signal is a numerical value. When the identification data is an even value, two sparse waves are continuously generated, and when the identification data is an odd value, three sparse waves are continuously generated. By doing so, the receiving device 2 can easily determine whether or not the incoming dense wave corresponds to the received identification data. In this example, only two types of sparse / dense waves are distinguished, so identification data and sparse / dense waves are not associated one-to-one. It is possible to reduce the possibility that the direction is different from that of the transmission device 1 that transmits the identification data.

  In the configuration of the present embodiment, it is needless to say that the reception device 2 also needs to associate the reception pattern of the sparse / dense wave with the identification data. In the control unit 20 used as the position calculation unit, the data It is determined whether or not the received pattern of the received data stored in the storage unit 24 corresponds to the identification data input from the identification data receiving unit 22, and if not, the received data is Discard. By this processing, it is possible to prevent the received wave data not corresponding to the identification data from being used for position detection. Other configurations and operations are the same as those of the first embodiment.

(Embodiment 3)
In the present embodiment, as shown in FIG. 11, the identification data transmission path using infrared as a transmission medium is omitted from the configuration of the first embodiment. In the present embodiment, a configuration is adopted in which identification data is transmitted by dense waves instead of using infrared rays. In other words, in the receiving device 2, the position of the transmitting device 1 is detected using the dense wave transmitted from the dense wave transmitting unit 11, and the transmitting device 1 is identified by extracting the identification data included in the dense wave. To do. Accordingly, the sparse / dense wave transmission unit 11 is also used as the identification data transmission unit 12, and the sparse / dense wave reception unit 21 is also used as the identification data reception unit 22.

  In the present embodiment, an identification pattern generation unit 15 is provided in the same manner as in the second embodiment in order to transmit identification data using a dense wave. The identification pattern generation unit 15 generates identification data with a fixed number of sparse and dense waves, and represents bit values at time intervals at which the sparse and dense waves are transmitted. Here, it is assumed that the identification data is represented by 8 bits and 9-bit data to which a 1-bit start bit is added is represented by a dense wave. That is, since the bit value is represented by the time interval for transmitting the sparse / dense wave, 10 sparse / dense waves are transmitted at a time.

  Assume that an appropriate unit time is T, a bit value “1” is associated with an appropriate time interval in which the time interval of the sparse / dense wave is 6T or more and 8T or less, and a bit value “0” is the time interval of the sparse / dense wave. Assume that it is associated with an appropriate time interval that is not less than 10T and not more than 12T. As an example, it is assumed that 7T is associated with “1” and 11T is associated with “0”. The start bit is assumed to be “1”.

  If there are two transmitters 1, one identification data is “01010101”, the other identification data is “11111111”, and transmission of dense waves from both transmitters 1 is started simultaneously, If the loose waves transmitted from each transmission device 1 are received independently by the reception device 2, the reception data as shown in FIGS. 12 (a) and 12 (b) is obtained. Therefore, the receiving device 2 actually obtains received data as shown in FIG. As can be seen from the figure, the time interval of the sparse / dense waves received by the receiving device 2 is shorter than 6T. The receiving device 2 determines the identification data in units of ten sparse / dense waves, but receives sparse / dense waves at a time interval shorter than 6T even after the tenth sparse / dense wave.

  Also, there are two transmitters 1, one identification data is “01010101”, the other identification data is “00000000”, and transmission of dense waves from both transmitters 1 starts simultaneously. Assuming that the reception device 2 receives the sparse / dense wave transmitted from each transmission device 1 independently, the reception data as shown in FIGS. 13A and 13B is obtained. That is, the receiving device 2 actually obtains received data as shown in FIG. In this case, the time intervals of the dense waves received by the receiving device 2 include those with a time interval shorter than 7T until the tenth, and the time intervals shorter than 11T after the tenth dense wave. I am receiving sparse waves.

  As another example, the identification data transmitted from one of the two transmission apparatuses 1 is “01010101”, the identification data transmitted from the other is “10101010”, and the other is preceded by 7T, and the transmission / reception of dense waves is performed. Assuming a case where a wave is started, if the dense waves transmitted from each transmitting device 1 are received independently by the receiving device 2, received data as shown in FIGS. 14A and 14B can be obtained. . Accordingly, the dense wave received by the receiving device 2 is actually as shown in FIG. 14C, and the tenth dense wave coincides with the dense wave from the transmitting device 1 that has started transmission in advance. To do. However, the eleventh dense wave is detected in the received data obtained by the receiving device 2, and the time interval between the tenth and eleventh dense waves is 11T or less.

  From the results of FIGS. 12, 13, and 14, (1) the time interval of up to 10th dense wave is shorter than 6T, and (2) the dense wave can be obtained within 11T after the 10th dense wave. If at least one of the two conditions is satisfied, it is determined that interference has occurred, and the received sparse / dense wave is invalidated. When interference is detected, the received sparse / dense wave is ignored until the period during which the sparse / dense wave is not received reaches 12T or more. Since the maximum time required to transmit identification data using a sparse / dense wave is 95T (in the case of “00000000”), if T = 10 μs, one identification data can be transmitted at most 1 ms. .

  In the present embodiment, if a plurality of transmitters 1 are used and the period at which each transmitter 1 transmits identification data is set to 50 + 50R (ms) (R is a random number uniformly distributed from 0 to 1), 1 About 10 transmitters 1 can exist simultaneously in the area monitored by one receiver 2.

  In addition, although identification data is transmitted by a density wave, position detection is transmitted and received during a wave reception possible time set after transmission of identification data. Other configurations and operations are the same as those of the first embodiment.

  In the configuration of the present embodiment, the identification data is transmitted using a sparse / dense wave, so that the position can be detected using the sparse / dense wave that transmits the identification data. In this case, the position can be detected by using at least one of the 10 dense waves as a group, but the average value of the positions obtained by the plurality of dense waves is obtained. If it is made, the reliability of a detection result can be improved. Needless to say, when interference is detected, the detection result is discarded.

1 is a block diagram illustrating a first embodiment. It is a schematic block diagram which shows the usage example same as the above. It is operation | movement explanatory drawing same as the above. It is operation | movement explanatory drawing same as the above. It is operation | movement explanatory drawing same as the above. It is operation | movement explanatory drawing of the other operation example same as the above. It is sectional drawing which shows an example of the wave transmission element used for the same as the above. It is operation | movement explanatory drawing same as the above. An example of the wave receiving element used for the above is shown, (a) is a partially broken perspective view, and (b) is a sectional view. 6 is a block diagram illustrating a transmission apparatus used in Embodiment 2. FIG. FIG. 6 is a block diagram illustrating a third embodiment. It is operation | movement explanatory drawing same as the above. It is operation | movement explanatory drawing same as the above. It is operation | movement explanatory drawing same as the above.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Transmission apparatus 2 Reception apparatus 10 Control part 11 Density / wave transmission part 12 Identification data transmission part 15 Identification pattern generation part 20 Control part (Position calculation part, reception time restriction | limiting part)
21 Density wave reception unit 22 Identification data reception unit 23 A / D converter 24 Data storage unit 25 Timing control unit (wave reception time limit unit)
40 receiving element

Claims (5)

  A transmitting device mounted on a detection target for position detection and transmitting at least a dense wave intermittently, and a relative direction and distance in which the detection target exists by receiving a dense wave transmitted from the detection target A flow line measuring system for tracking a position where a detection target has moved by detecting the position of the transmission device by the reception device, the transmission device comprising: a sparse wave transmission unit for transmitting a sparse wave; An identification data transmission unit that transmits unique identification data using a wireless signal, and the reception device receives the density wave transmitted from the density wave transmission unit and receives the density signal as an electrical signal. The dense wave receiving unit composed of an array sensor in which a plurality of receiving elements to be converted into received signals are arranged, and the time difference between the receiving times of the dense waves by each receiving element of the dense wave receiving unit and each received wave Density waves based on the location of the element Identifies the position calculation unit that determines the direction in which the detection target exists with respect to the wave unit, the identification data reception unit that receives identification data from the identification data transmission unit, and the period during which the dense wave reception unit receives the dense wave A flow line measurement system comprising: a reception time limiter configured to limit within a predetermined reception time set after data is received.   The reception time limit unit starts a reception possible time after a predetermined delay time from the time when the identification data reception unit receives the identification data, and the delay time is the minimum allowable distance between the detection target and the reception device. 2. The flow line measuring system according to claim 1, wherein the time is required for the dense wave to reach from the transmitting device to the receiving device.   The identification data transmission unit intermittently transmits the identification data at a constant time interval, and the transmission device uses the random number generated in response to an instruction to set the time interval for transmitting the identification data. 3. The flow line measuring system according to claim 1, further comprising means for irregularly setting the value.   An identification pattern generation unit that associates a transmission pattern of the dense wave transmitted from the dense wave transmission unit with identification data transmitted from the identification data transmission unit; and the position calculation unit is the dense wave reception unit. 2. The direction in which the detection target exists is obtained using the sparse / dense wave when a received pattern of the received sparse / dense wave corresponds to the identification data received by the identification data receiving unit. The flow line measurement system according to any one of claims 3 to 4.   The identification data transmitting unit uses a dense wave transmitted from the dense wave transmitting unit as a transmission medium and represents the identification data as a fixed-length bit string, and each bit value is associated with a time interval for transmitting the dense wave. The flow line measurement system according to any one of claims 1 to 3, wherein the flow line measurement system is provided.

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