JP4100415B2 - Position detection system - Google Patents

Description

  The present invention relates to a position detection system that detects position information of an object to be detected using ultrasonic waves.

Conventionally, an ultrasonic transmitter provided in each of a plurality of moving bodies, at least three ultrasonic receivers installed for each predetermined area of a ceiling surface in a building, and an ultrasonic transmitter transmitted from the ultrasonic transmitter There has been proposed a position detection system including an arithmetic processing means for obtaining position information of a moving body based on a time until a sound wave is received by an ultrasonic receiver (for example, see Patent Documents 1 and 2). In the position detection systems disclosed in Patent Documents 1 and 2, each ultrasonic receiver is connected to a junction box with a two-wire signal line, and a computer and a junction box constituting the arithmetic processing means are separately provided. Are connected via the signal line.
JP 2003-279640 A (paragraphs [0012] to [0024], FIGS. 1 to 4) JP-A-8-226810 (paragraphs [0025] to [0033], FIGS. 1 to 3)

  The position detection systems disclosed in Patent Documents 1 and 2 are systems in which one ultrasonic receiving device including an ultrasonic receiver is installed for each predetermined area on the ceiling surface of a building, In order to obtain the position information of the object (moving body) to be detected by the means, it is necessary to install ultrasonic receiving devices in at least three places, and the construction work becomes troublesome. In addition, in the above-described position detection system, only the position information of the object existing in the area where the detection areas of the three ultrasonic reception devices overlap can be obtained, so the layout design of the ultrasonic reception device is difficult and the construction work is troublesome. turn into.

  The present invention has been made in view of the above-described reasons, and an object of the present invention is to provide a position detection system that is easy to construct and that allows easy layout design of an ultrasonic receiver.

According to the first aspect of the present invention , there is provided a sound source that is mounted on a position detection target object that moves on a floor surface in a building, can generate ultrasonic waves, and has a resonance characteristic Q value of about 1 , and a construction surface in the building. The ultrasonic wave transmitted from a sound source installed at a fixed position on a certain ceiling surface is received, and the received ultrasonic wave is converted into a received signal which is an electric signal, and the Q value of the resonance characteristic is about 3 to 4. An ultrasonic receiving device including an ultrasonic array sensor in which a plurality of receiving elements are two-dimensionally arranged on the same substrate and an ultrasonic receiving device of the ultrasonic array sensor that is an ultrasonic receiving device receive ultrasonic waves. Provided on the sound source side of the sound source and the ultrasonic receiver, and a position calculation unit for obtaining the direction in which the sound source exists for the ultrasonic receiver based on the time difference between the waved times and the arrangement position of each receiving element A trigger signal transmitter that emits a light or radio trigger signal, and an ultrasonic A trigger signal receiver provided on the receiving device side for receiving a trigger signal, and a control unit for controlling the transmission start timing of the trigger signal from the trigger signal transmitter and the transmission start timing of the ultrasonic wave from the sound source, The position calculation unit includes distance calculation means for obtaining a distance between the ultrasonic receiver and the sound source from the relationship between the time when the trigger signal is received by the trigger signal receiver and the time when the ultrasonic wave is received by the wave receiving element. Features.

According to the present invention, by arranging one ultrasonic receiving device, it is possible to obtain the direction in which the sound source mounted on the object existing in the detection area centered on the ultrasonic receiving device is present. This facilitates the layout design of the ultrasonic receiver. In addition, since the distance between the ultrasonic receiving device and the sound source can be obtained, the relative position of the sound source with respect to the ultrasonic receiving device can be obtained based on the direction in which the sound source exists and the distance to the sound source. In addition, since the Q value of the resonance characteristics of the sound source and the receiving element is sufficiently smaller than that of the piezoelectric element, the dead zone due to the reverberation component can be shortened. Resolution is improved.
The invention of claim 2 includes a sound source that is mounted on a position detection target object that moves on a floor surface in a building and that can generate an ultrasonic wave and a resonance characteristic Q value of about 1 , and a construction surface in the building. The ultrasonic wave transmitted from a sound source installed at a fixed position on a certain ceiling surface is received, and the received ultrasonic wave is converted into a received signal which is an electric signal, and the Q value of the resonance characteristic is about 3 to 4. An ultrasonic receiving device including an ultrasonic array sensor in which a plurality of receiving elements are two-dimensionally arranged on the same substrate and an ultrasonic receiving device of the ultrasonic array sensor that is an ultrasonic receiving device receive ultrasonic waves. A position calculation unit for obtaining an azimuth in which the sound source exists with respect to the ultrasonic receiving device based on the time difference between the waved times and the arrangement position of each receiving element, and the ultrasonic receiving device side of the sound source and the ultrasonic receiving device Trigger signal transmission to transmit light or radio wave trigger signal A trigger signal receiver that is provided on the sound source side and receives a trigger signal; and a control unit that transmits ultrasonic waves from the sound source when the trigger signal is received by the trigger signal receiver. It is characterized by comprising distance calculation means for obtaining the distance between the ultrasonic receiver and the sound source from the relationship between the time when the trigger signal is transmitted from the trigger signal transmitter and the time when the ultrasonic wave is received by the wave receiving element.
According to the present invention, by arranging one ultrasonic receiving device, it is possible to obtain the direction in which the sound source mounted on the object existing in the detection area centered on the ultrasonic receiving device is present. This facilitates the layout design of the ultrasonic receiver. In addition, since the distance between the ultrasonic receiver and the sound source can be obtained, the relative position of the sound source with respect to the ultrasonic receiver is obtained based on the direction in which the sound source exists and the distance between the ultrasonic receiver and the sound source. Can do. In addition, since the Q value of the resonance characteristic between the sound source and the receiving element is sufficiently smaller than that of the piezoelectric element, the dead zone due to the reverberant component can be shortened, and in particular, the angle can be reduced by shortening the dead zone for the receiving element. Resolution is improved.

The invention of claim 3 is the invention of claim 1 , wherein there are a plurality of the sound sources, and a plurality of sound sources provided on the sound source side of the sound sources and the ultrasonic receivers, each transmitting a unique identification information signal. An identification information signal transmitter; and an identification information signal receiver provided on the ultrasonic receiver side for receiving an identification information signal, wherein the trigger signal transmitter uses the identification information signal transmitter and the trigger signal receiver. As the identification information signal receiver, the trigger signal is also used as the identification information signal, and the control unit is provided on the sound source side and the transmission start timing of the identification information signal from the identification information signal transmitter and from the sound source The position calculation unit controls the transmission start timing of the ultrasonic wave, and the position calculation unit specifies the sound sources individually based on the identification information signal received by the identification information signal reception unit. The distance calculating means includes a relationship between a time at which the identification information signal is received by the identification information signal receiving unit and a time at which the ultrasonic wave is received by the receiving element. It is characterized by obtaining a distance.
According to this invention, since the distance from the ultrasonic receiver to each of the sound sources can be obtained, the azimuth in which each of the sound sources exists and the distance from the ultrasonic receiver to each of the sound sources. Based on this, it is possible to obtain the relative position of each sound source with respect to the ultrasonic receiving device.
According to a fourth aspect of the present invention, in the first or third aspect of the present invention, the flow line measurement for tracking the movement of the object is performed using the direction and distance of the sound source at each time when the trigger signal is received. .
According to the present invention, it is possible to track the movement of a position detection target object that is a moving body.
According to a fifth aspect of the present invention, in the first or second aspect of the present invention, there are a plurality of the sound sources, and each of the sound sources and the ultrasonic receiving device is provided on the sound source side and has a unique identification information signal. An identification information signal transmitter for transmitting, an identification information signal receiver for receiving an identification information signal provided on the ultrasonic receiving device side, and an identification received by an identification information signal receiving unit provided on the ultrasonic receiving device side Sound source specifying means for individually specifying each sound source based on an information signal.
According to the present invention, the direction in which each of the sound sources exists with respect to the ultrasonic receiving apparatus can be specified and determined for each sound source.
According to a sixth aspect of the present invention, in the first to fifth aspects of the invention, the sound source is supported on a support substrate, a heating element layer formed on one surface side of the support substrate, and the one surface side of the support substrate. A thermal insulating layer interposed between the substrate and the heating element layer, and comprising an ultrasonic wave generating element that generates an ultrasonic wave in accordance with a temperature change of the heating element layer caused by energization of the heating element layer. To do.

  According to this invention, since the Q value of the resonance characteristics is small compared to the case where a piezoelectric ultrasonic generator is used as the sound source, it is possible to generate ultrasonic waves with a short reverberation time and a short generation period. The dead zone caused by the reverberation component in the ultrasonic wave transmitted from the sound source can be shortened.

According to a seventh aspect of the present invention, in the first to sixth aspects of the invention, the wave receiving element comprises a capacitive microphone that converts an ultrasonic sound pressure into a change in capacitance. To do.

  According to the present invention, since the Q value of the resonance characteristic of the receiving element is smaller than the Q value of the resonance characteristic of the piezoelectric element, the piezoelectric receiving element is used as the receiving element as in the prior art. Since the reverberation time in the received signal generated when receiving the ultrasonic wave by the receiving element can be shortened, the dead zone caused by the reverberant component in the received signal output from the receiving element can be shortened. Can do.

The invention of claim 8 is characterized in that, in the inventions of claims 1 to 7 , the distance between the centers of the receiving elements is set to about 0.5 to 5 times the wavelength of the ultrasonic wave.
According to the present invention, the time difference can be easily detected by taking the time difference in which the ultrasonic waves reach each adjacent receiving element.
The invention of claim 9 is the invention of claims 1 to claim 8, wherein the wave receiving element you characterized in that it is formed by utilizing the micromachining technology.

  In the invention of claim 1, by arranging one ultrasonic receiving device, it is possible to determine the direction in which the sound source mounted on the object existing in the detection area centered on the ultrasonic receiving device exists, There is an effect that the construction becomes easy and the arrangement design of the ultrasonic receiving device becomes easy.

  In the present embodiment, as the position detection system, as shown in FIG. 1A, the object A as a position detection target is a moving body (for example, a shopping cart) that moves on the floor surface 100 in a building, and is intermittent. On the other hand, the sound source unit 1 having the sound source 11 (see FIG. 2) capable of generating ultrasonic waves is mounted on the upper surface of the object A, while receiving the ultrasonic waves intermittently transmitted from the sound source 11. The sensor unit 2 provided with the receiving device 21 (see FIG. 2) is installed at a fixed position on the ceiling surface 200 that is the construction surface, and the relative position of the object A with respect to the ultrasonic receiving device 21 is obtained as the relative position of the sound source 11, and the object The flow line measurement system which performs the flow line measurement which tracks the movement condition (movement of the object A) of A is illustrated.

  The sound source unit 1 includes the above-described sound source 11, a driver 12 that drives the sound source 11, a trigger signal transmitter 13 that transmits a trigger signal made of light or radio waves, and a driver 14 that drives the trigger signal transmitter 13. An identification information signal transmitter 15 that transmits a unique identification information signal, a driver 16 that drives the identification information signal transmitter 15, and a control unit 17 that controls the drivers 12, 14, and 16 are provided. Here, the transmission start timing of the ultrasonic wave from the sound source 11, the transmission start timing of the trigger signal from the trigger signal transmitter 13, and the transmission timing of the identification information signal from the identification information signal transmitter 15 are controlled by the control unit 17. Is done. The control unit 17 includes a microcomputer as a main component, and the functions of the control unit 17 described above are realized by installing an appropriate program in the microcomputer.

  On the other hand, the sensor unit 2 includes a trigger signal receiver 23 that outputs a trigger reception signal when receiving the trigger signal transmitted from the trigger signal transmitter 13, the trigger signal transmitter 13, and an identification information signal transmission. Based on the identification information signal receiver 25 that receives the identification information signal transmitted from the receiver 15, the received signal output from the ultrasonic receiver 21, and the trigger reception signal output from the trigger signal receiver 23. The position calculation unit 22 that obtains and outputs the relative position of the sound source 11 with respect to the sound wave receiving device 21 (the direction in which the sound source 11 exists and the distance to the sound source 11), and the time when the trigger reception signal is received from the trigger signal receiver 23 ( Hereinafter, the timer 26 that outputs the trigger reception time) and the calculation result (the direction in which the sound source 11 exists and the distance to the sound source 11) output from the position calculation unit 22 are output. ) A and a memory 24 for time series stored in association with the trigger receiving time output from the timer 26. The trigger reception time stored in the memory 24, the azimuth of the sound source 11 at each trigger reception time, and the distance to the sound source 11 (in short, data relating to changes in the time-series relative position of each sound source 11) are the control unit. 27 is converted to a data string in the data transfer format of the output unit 28 and output to a management device such as an external computer through the output unit 28. As the output unit 28, for example, a serial transfer system interface such as TIA / EIA-232-E or USB, a parallel transfer system interface such as SCSI, or the like can be employed. The function of the control unit 27 is realized by installing an appropriate program in the microcomputer.

As the sound source 11 of the sound source unit 1, a piezoelectric ultrasonic generating element using mechanical vibration due to the piezoelectric effect may be used. Such a piezoelectric ultrasonic generating element (piezoelectric element) has a resonance characteristic. Since the Q value (mechanical quality factor Q _m ) is generally higher than 100, the reverberation time becomes long. Therefore, in order to intermittently generate an ultrasonic wave having a short reverberation time from the sound source 11 (that is, to intermittently generate an ultrasonic wave having a short generation period), as shown in FIG. A thermal insulation layer (heat insulation layer) 32 made of a porous silicon layer is formed on one surface (upper surface in FIG. 3) of the support substrate 31 made of a p-type silicon substrate, and a metal thin film (for example, Thermally-excited ultrasonic wave generation in which a heating element layer 33 made of a tungsten thin film is formed and a pair of pads 34, 34 electrically connected to the heating element layer 33 is formed on the one surface side of the support substrate 31. It is desirable to use an element. The planar shape of the support substrate 31 is a rectangular shape, and the planar shapes of the heat insulating layer 32 and the heating element layer 33 are also rectangular.

  In the thermal excitation type ultrasonic wave generating element, when a temperature change is caused in the heating element layer 33 by energizing the pads 34, 34 at both ends of the heating element layer 33, the temperature of the air in contact with the heating element layer 33 is increased. Change occurs. 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 falls. Therefore, by appropriately controlling the energization of the heating element layer 33, Can be generated.

  In the above-described piezoelectric ultrasonic wave generating element, since the Q value of the resonance characteristic is high, the reverberation time like the ultrasonic waveform as shown in FIG. 5 becomes long. In the element, an ultrasonic wave is generated in accordance with a temperature change of the heating element layer 33 accompanying energization of the heating element layer 33 via the pair of pads 34, 34, and a driving voltage or driving applied to the heating element layer 33 is generated. When the current waveform is, for example, a sine wave waveform having a frequency of f1, an ultrasonic wave having a frequency approximately twice that of the frequency f1 can be generated. By applying from 12 to the pair of pads 34, 34, it is possible to generate an ultrasonic wave of approximately one cycle having a short reverberation time and a short generation period as shown in FIG. In short, piezoelectric ultrasonic generators have a specific resonance frequency, so the frequency band is narrow. However, thermal excitation ultrasonic generators can change the frequency of generated ultrasonic waves over a wide range, and drive If the waveform of the voltage or drive current is an isolated wave, it is possible to generate an ultrasonic wave having approximately one cycle as shown in FIG.

In the above-described thermal excitation type ultrasonic wave generating element, a p-type silicon substrate is used as the support substrate 31, and the heat insulating layer 32 is composed of a porous silicon layer having a porosity of approximately 70%. A porous silicon layer serving as the thermal insulating layer 32 can be formed by anodizing a part of a silicon substrate used as the substrate 31 in an electrolytic solution composed of a mixed solution of hydrogen fluoride aqueous solution and ethanol. Here, by appropriately setting the 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. . The porous silicon layer has a smaller thermal conductivity and heat capacity as the porosity increases. For example, the thermal conductivity is 148 W / (m · K), and the heat capacity is 1.63 × 10 ⁶ J / (m ³ · K. The porous silicon layer having a porosity of 60% formed by anodizing a single crystal silicon substrate of) 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 thermal insulating layer 32 is configured by a porous silicon layer having a porosity of approximately 70%, and the thermal conductivity of the thermal insulating layer 32 is 0.12 W / (m · K), The heat capacity is 0.5 × 10 ⁶ J / (m ³ · K). The thermal conductivity and thermal capacity of the thermal insulating layer 32 are made smaller than the thermal conductivity and thermal capacity of the support substrate 31, and the product of the thermal conductivity and thermal capacity of the thermal insulating layer 32 is calculated as the thermal conductivity of the support substrate 31. By making it sufficiently smaller than the product of the heat capacity, the temperature change of the heating element layer 33 can be efficiently transmitted to the air, and efficient heat exchange occurs between the heating element layer 33 and the air, and The support substrate 31 can efficiently receive the heat from the heat insulating layer 32 and release the heat of the heat insulating layer 32, thereby preventing the heat from the heating element layer 33 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). It has become. 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 ultrasonic wave generating element described above, the thickness of the support substrate 31 is 525 μm, the thickness of the thermal insulation layer 32 is 10 μm, the thickness of the heating element layer 33 is 50 nm, and the thickness of each pad 34 is Although the thickness is 0.5 μm, these thicknesses are merely examples and are not 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.

  For example, a light emitting diode may be used as the trigger signal transmitter 13 when light is used as the trigger signal. For example, a radio wave transmitter may be used when a radio wave is used as the trigger signal. Here, since light and radio waves are sufficiently fast with respect to sound waves, the arrival time of light and radio waves can be regarded as zero in the range of arrival times of sound waves from the sound source unit 1 to the sensor unit 2.

  As the identification information signal transmitter 15, for example, a light emitting diode may be used when light is used as the identification information signal, and when a radio wave is used as the identification information signal, for example, a radio wave transmitter may be used. When a sound wave is adopted as the identification information signal, for example, a thermal excitation type sound wave generating element may be used.

  As shown in FIG. 1B, the ultrasonic receiver 21 of the sensor unit 2 receives the ultrasonic wave transmitted from the sound source 11 and converts the received ultrasonic wave into a received signal that is an electric signal. A plurality of receiving elements 21a (four in the illustrated example, but the number is not particularly limited) is constituted by an ultrasonic array sensor in which the receiving elements 21a are two-dimensionally arranged on the same substrate 21b. . Here, it is desirable to set the center-to-center distance (arrangement pitch) L of the wave receiving elements 21a to about the wavelength of the ultrasonic wave generated from the sound source 11 (for example, about 0.5 to 5 times the wavelength of the ultrasonic wave). If it is smaller than 0.5 times the wavelength of the ultrasonic wave, the time difference between the time when the ultrasonic wave reaches each adjacent receiving element 21a becomes small, and it becomes difficult to detect the time difference. As the wave receiving element 21a, for example, a piezoelectric wave receiving element (piezoelectric element) that converts an ultrasonic wave into an electric signal by a piezoelectric effect, or a capacitance wave receiving wave that converts an ultrasonic wave into a change in capacitance. Although it is conceivable to adopt a widely known ultrasonic wave receiving element such as an element, the structure of a capacitive wave receiving element is adopted in order to reduce reverberation in the same manner as the sound source 11. It is desirable to do.

  In the present embodiment, a capacitive microphone as shown in FIG. 6 is employed as the wave receiving element 21a. The capacitance type microphone having the configuration shown in FIG. 6 is formed using a micromachining technique, and is a rectangular frame-shaped frame 41 formed by providing a window hole 41a penetrating in the thickness direction in a silicon substrate. And a cantilever-type pressure receiving portion 42 disposed on one surface side of the frame 41 so as to straddle two opposing sides of the frame 41. Here, a thermal oxide film 45, a silicon oxide film 46 covering the thermal oxide film 45, and a silicon nitride film 47 covering the silicon oxide film 46 are formed on one surface side of the frame 41, and one end portion of the pressure receiving portion 42. Is supported by the frame 41 through the silicon nitride film 47, and the other end faces the silicon nitride film 47 in the thickness direction of the silicon substrate. In addition, a fixed electrode 43 a made of a metal thin film (for example, a chromium film) is formed on the surface of the silicon nitride film 47 facing the other end of the pressure receiving portion 42, and the silicon nitride film 47 at the other end of the pressure receiving portion 42 A movable electrode 43b made of a metal thin film (for example, a chromium film) is formed on the opposite side of the opposite surface. A silicon nitride film 48 is formed on the other surface of the frame 41. The pressure receiving portion 42 is constituted by a silicon nitride film formed in a separate process from the silicon nitride films 47 and 48 described above.

  In the wave receiving element 21a composed of a capacitance type microphone having the configuration shown in FIG. 6, a capacitor having the fixed electrode 43a and the movable electrode 43b as electrodes is formed, so that the pressure receiving portion 42 receives the pressure of the sound wave. As a result, the distance between the fixed electrode 43a and the movable electrode 43b changes, and the capacitance between the fixed electrode 43a and the movable electrode 43b changes. Therefore, if a DC bias voltage is applied between pads (not shown) provided on the fixed electrode 43a and the movable electrode 43b, a minute voltage change occurs between the pads in accordance with the sound pressure of the ultrasonic waves. The sound pressure of ultrasonic waves can be converted into an electric signal.

  Note that the structure of the capacitance type microphone used as the wave receiving element 21a is not particularly limited to the structure shown in FIG. 6, and is formed by processing a silicon substrate or the like by a micromachining technique or the like, and receives ultrasonic waves. Between the movable electrode made of the diaphragm and the fixed electrode made of the back plate facing the diaphragm, an insulating film that defines the gap length between the diaphragm and the back plate in a state where no ultrasonic waves are received. It may have a structure in which a plurality of exhaust holes are provided in the back plate portion. In such a capacitance type microphone, the diaphragm portion receives the ultrasonic wave and is deformed to change the distance between the diaphragm portion and the back plate portion, so that the capacitance between the movable electrode and the fixed electrode is increased. Change.

  Incidentally, the sound source 11 composed of the thermal excitation type sound wave generating element shown in FIG. 3 has a resonance characteristic Q value of about 1, and the resonance characteristic of the wave receiving element 21a composed of the capacitance type microphone shown in FIG. The Q value is about 3 to 4, and the Q value is sufficiently smaller than that of the piezoelectric element. Compared to the case where the piezoelectric element is used for the transmitting element and the receiving element as in the prior art, the Q value is transmitted from the sound source 11. The dead zone caused by the reverberation component in the ultrasonic wave to be waved can be shortened, and the reverberation time in the received signal generated when the ultrasonic wave is received by the wave receiving element 21a can be shortened. Since the dead zone due to the reverberation component in the output received signal can be shortened, the angular resolution can be improved. In addition, since the capacitance type microphone does not have a high Q value having a resonance characteristic unlike a piezoelectric element, it is possible to widen the range of the reception frequency. Further, the Q values of the resonance characteristics of the sound source 11 and the receiving element 21a are both preferably 10 or less, and more preferably 5 or less.

  The trigger signal receiver 23 may use a photodiode, for example, when light is used as the trigger signal transmitted from the trigger signal transmitter 13, and may receive, for example, a radio wave when using a radio wave as the trigger signal. An antenna may be used. In short, the trigger signal receiver 23 only needs to be able to receive the trigger signal, convert the trigger signal into an electrical signal (trigger reception signal), and output the electrical signal.

  When the identification information signal receiver 25 employs light as the identification information signal transmitted from the identification information signal transmitter 15, for example, a photodiode may be used, and when the radio wave is employed as the identification information signal, For example, a radio wave receiving antenna may be used, and when a sound wave is adopted as the identification information signal, for example, a capacitive receiving element may be used. In short, the identification information signal receiver 25 only needs to be capable of receiving the identification information signal, converting the identification information signal into identification information including an electric signal, and outputting the identification information.

  The position calculation unit 22 is based on the time difference between the time when each wave receiving element 21a of the ultrasonic array sensor which is the ultrasonic wave receiving apparatus 21 receives the sound wave and the arrangement position of each wave receiving element 21a. The azimuth angle θ (the direction of arrival of ultrasonic waves) indicating the azimuth in which the sound source 11 exists is obtained.

Hereinafter, the position calculation unit 22 will be described. For simplicity of explanation, the receiving elements 21a of the ultrasonic receiving device 21 are arranged one-dimensionally at equal intervals on the same plane as shown in FIG. An example will be described. Assuming that the angle of the wavefront of the ultrasonic wave with respect to the surface on which the wave receiving elements 21 a are arranged is θ ₀ , the arrival direction of the ultrasonic wave (that is, the azimuth angle where the sound source 11 exists with respect to the ultrasonic wave reception device 21). Becomes θ ₀ , the sound velocity is c, and the ultrasonic wavefront at the time when the ultrasonic wavefront reaches one of the adjacent receiving elements 21a and the center of the other receiving element 21a are If the distance (delay distance) between them is d ₀ , and the distance between the centers of the adjacent wave receiving elements 21 a is L, the time difference Δt _{0 when the} ultrasonic wavefront reaches between the adjacent wave receiving elements 21 a (see FIG. 8). Is Δt ₀ = d ₀ / c = L · sin θ ₀ / c.

  8A to 8C show the wave receiving elements 21a shown in FIG. 7 when a driving voltage having a half-cycle waveform of a sine wave is applied to the heating element layer 33 of the above-described thermal excitation type ultrasonic wave generating element. FIG. 8A shows a received signal of the top receiving element 21a in FIG. 7, and FIG. 8B shows a received signal of the middle receiving element 21a in FIG. FIG. 8C shows the received signal of the lowermost receiving element 21a in FIG. Here, the position calculation unit 22 includes a signal processing unit 22c having a calculation function for obtaining the direction in which the sound source 11 exists. The signal processing unit 22c is a received signal obtained by delaying a received signal that is an electrical signal output from each receiving element 21a of the ultrasonic receiving device 21 by a delay time corresponding to the arrangement pattern of each receiving element 21a. A delay means for outputting a set of signals, an adder for adding a set of received signals delayed by the delay means, and comparing the magnitude relationship between the peak value of the output waveform of the adder and an appropriate threshold value, and exceeding the threshold value Since there is a judgment means for judging the direction corresponding to the delay time set by the delay means when the peak value is obtained as the direction in which the sound source 11 exists (the arrival direction of the ultrasonic wave), the ultrasonic reception The direction in which the sound source 11 exists (the arrival direction of the ultrasonic wave) can be detected with respect to the device 21. Here, in addition to the signal processing unit 22c described above, the position calculation unit 22 converts an analog reception signal output from each reception element 21a of the ultrasonic reception device 21 into a digital reception signal and outputs the digital reception signal. And an A / D converter 22a that stores the output of the A / D converter 22a for a predetermined reception period from when the trigger reception signal is input from the trigger signal receiver 23. The signal processing unit 22c sets a reception period when a trigger reception signal is input to the data storage unit 22b, operates the A / D conversion unit 22a only during the reception period, and receives the reception period. The direction in which the sound source 11 exists is obtained based on the received signal data stored in the data storage unit 22b. The signal processing unit 22c is configured by a microcomputer or the like. In addition, since data is stored in the data storage unit 22b by the number [number of receiving elements 21a] × [number of received signal data from each receiving element 21a], for example, If the number of the elements 21a is 8, the receiving period is 30 ms, and the sampling period of the A / D converter 22a is 1 μs, a capacity of 240 kwords is required with one data as one word, and 256 kwords An SRAM or the like may be used.

By the way, in the present embodiment, since the above-described thermal excitation type ultrasonic wave generating element is used as the sound source 11, as shown in FIG. 9, each wave receiving element 21 a of the ultrasonic wave receiving device 21 is superposed from two directions. If the ultrasonic wave arriving from the direction of the azimuth angle θ ₁ arrives earlier than the ultrasonic wave arriving from the direction of the azimuth angle θ _{2 when} the sound wave arrives, FIG. ), The two received signals output from the respective receiving elements 21a are unlikely to overlap, and the azimuth angles (arrival directions of ultrasonic waves) θ ₁ and θ ₂ existing from the respective sound sources 11 can be obtained. it can. Here, FIG. 10A shows two received signals of the top receiving element 21a of FIG. 9, FIG. 10B shows two received signals of the middle receiving element 21a of FIG. c) is shows the two received signals of wave receiving element 21a at the bottom of FIG. 9, the ultrasonic waves left received signal arrives from theta ₁ orientation in the respective (a) ~ (c) corresponding corresponds to ultrasonic waves right received signal arrives from theta ₂ orientation. It is to be noted that the ultrasonic wavefront from the direction of θ ₁ is between the ultrasonic wavefront and the center of the other receiving element 21a at the time when the ultrasonic wavefront from one of the adjacent receiving elements 21a reaches one receiving element 21a. If the distance (delay distance) is d ₁ (see FIG. 9), the time difference Δt ₁ (see FIG. 10) at which the wavefront of the ultrasonic wave reaches between adjacent receiving elements 21a is Δt ₁ = d ₁ / c = become L · sinθ _{1 /} c, ultrasonic wave at the time of reaching one of the wave receiving element 21a of the wave receiving devices 21a adjacent the ultrasound wavefront from theta ₂ orientation and the other wave receiving element If the distance (delay distance) from the center of 21a is d ₂ (see FIG. 9), the time difference Δt ₂ (see FIG. 10) that the ultrasonic wavefront reaches between the adjacent receiving elements 21a is Δt ₂ = d ₂ / c = L · sin θ ₂ / c.

  In addition, the signal processing unit 22c of the position calculation unit 22 includes the ultrasonic receiver 21 and the sound source 11 based on the relationship between the time when the trigger signal is received by the trigger signal receiver 23 and the time when the ultrasonic wave is received by the wave receiving element 21a. Distance calculating means for obtaining the distance between Here, as described above, a sufficiently high speed signal compared to sound waves such as light or radio waves is used as the trigger signal, so that the arrival time of the trigger signal from the sound source unit 1 to the sensor unit 2 is as follows. Since the arrival time of the trigger signal can be regarded as zero since the arrival time from 1 to the sensor unit 2 is sufficiently short (so short as to be negligible), the distance calculation means can perform the operations shown in FIGS. ), A time difference T between the time when the trigger reception signal ST is received via the data storage unit 22b and the time when the reception signal SP from the reception element 21a is first received after the reception of the trigger signal ST, The distance between the ultrasonic receiver 21 and the sound source 11 is obtained based on the speed of sound. The distance calculation means of the signal processing unit 22c is realized by mounting an appropriate program on the microcomputer that constitutes the signal processing unit 22c.

  Therefore, in the position detection system of the present embodiment, the single ultrasonic receiver 21 is arranged by placing one sensor unit 2 on the ceiling surface 200 that is the construction surface, so that the ultrasonic receiver 21 is centered. Since the direction in which the sound source 11 mounted on the object A existing in the detection area exists can be obtained, the construction is facilitated and the layout design of the ultrasonic receiving device 21 is facilitated.

  By the way, the floor surface 100 of the building to which the position detection system of this embodiment is applied is flat, the height from the floor surface 100 to the ceiling surface 200 is constant, and the size of the object A is constant (that is, If the height from the floor surface 100 to the upper surface of the object A is constant), the surface is parallel to the ceiling surface 200 and includes the ultrasonic receiving device 21, and is parallel to the ceiling surface 200 and is a sound source. 11 is a constant distance regardless of the position of the object A on the floor surface 100, the distance is stored in advance in the distance calculation means as known distance information (height information). Thus, the distance calculation means can determine the distance between the ultrasonic receiver 21 and the sound source 11 from the distance information and the direction in which the sound source 11 exists. On the other hand, the ultrasonic wave reception is performed from the relationship between the time when the distance calculation means of the signal processing unit 22c receives the trigger signal by the trigger signal receiver 23 and the time when the ultrasonic wave is received by the wave receiving element 21a as described above. By obtaining the distance between the device 21 and the sound source 11, the sound source of the ultrasonic receiver 21 of the sensor unit 2 and the sound source unit 1 even when there is a step 100 b on the floor 100 of the building as shown in FIG. 11 can be obtained with high accuracy, and the relative position of the sound source 11 with respect to the ultrasonic receiver 21 can be obtained with high accuracy.

  The control unit 27 includes sound source specifying means for individually specifying each sound source 11 based on the identification information output from the identification information signal receiving unit 25 and stored in the memory 24, and the ultrasonic receiving device 21. Even when there are a plurality of sound sources 11 in the detection area where ultrasonic waves can be detected, the relative positions of the sound sources 11 with respect to the ultrasonic receiver 21 can be obtained. Here, for example, when there are four objects A, the identification information signals transmitted from the identification information signal transmitters 15 of the sound source units 1 mounted on the respective objects A are shown in FIGS. As shown in FIG. 5, the identification information signal including different pulse trains is stored in the memory 24 in association with the identification information and the calculation result of the signal processing unit 22c of the position calculation unit 22. Therefore, in the control unit 27, the direction from which the sound source 11 exists (the arrival direction of the ultrasonic wave) obtained by the position calculation unit 22 and the distance between the ultrasonic receiving device 21 and the sound source 11 are determined from any sound source unit 1. Can be identified. Assuming the case where one sound source unit 1 exists in a detection area in which light or radio waves are adopted as the identification information signal and the ultrasonic wave reception device 21 can detect the ultrasonic wave, the identification information signal reception of the sensor unit 2 is received. The relationship between the identification information output from the receiver 25 and the received signal output from each of the receiving elements 21a is as shown in FIGS. 14 (a) to 14 (c). The trigger signal transmitter 13 can also be used (the identification information signal can also be used as a trigger signal). In this case, the sound source specifying means may be provided in the position calculation unit 22. Here, FIG. 14A shows the received signal of the top receiving element 21a in FIG. 7, FIG. 14B shows the received signal of the middle receiving element 21a in FIG. 7, and FIG. Indicates a received signal of the lowermost receiving element 21a in FIG.

  In the above embodiment, the trigger signal transmitter 13 is provided in the sound source unit 1 and the trigger signal receiver 23 is provided in the sensor unit 2, but the trigger signal transmitter 13 is provided on the sensor unit 2 side and the trigger signal is received. The controller 23 is provided on the sound source unit 1 side, and the control unit 17 controls the driver 12 so that an ultrasonic wave is transmitted from the sound source 11 based on the output of the trigger signal receiver 23. The distance calculation means of the signal processing unit 22c obtains the distance to the sound source 11 from the relationship between the time when the trigger signal is transmitted from the trigger signal transmitter 13 and the time when the ultrasonic wave is received by the wave receiving element 21a. Also good. Here, the control unit 17 may control the driver 12 immediately when the trigger reception signal output from the trigger signal receiver 23 is input, or may control the driver 12 after a predetermined time. Also good.

1A is a schematic configuration diagram of a position detection system, and FIG. 1B is a schematic perspective view of an ultrasonic array sensor. It is a block diagram same as the above. It is a schematic sectional drawing of the thermal excitation type ultrasonic wave generation element same as the above. It is operation | movement explanatory drawing of the thermal excitation type ultrasonic wave generation element same as the above. It is operation | movement explanatory drawing of the piezoelectric type ultrasonic generation element in the same as the above. The electrostatic capacitance type microphone in the same as above is shown, (a) is a schematic perspective view partly broken, and (b) is a schematic sectional view. 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 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 same as the above.

Explanation of symbols

A object 1 sound source unit 2 sensor unit 11 sound source 12 driver 17 control unit 21 ultrasonic receiving device 21a receiving element 21b substrate 22 position calculation unit 24 memory 27 control unit 28 output unit

Claims (9)

It is mounted on a position detection target object that moves on the floor in the building, can generate ultrasonic waves, and has a resonance characteristic Q value of about 1 and a fixed position on the ceiling surface that is the construction surface in the building. There are a plurality of receiving elements that receive an ultrasonic wave transmitted from a sound source and convert the received ultrasonic wave into a received wave signal that is an electric signal and have a resonance characteristic Q value of about 3 to 4. The time difference between the time when the ultrasonic wave is received by each wave receiving element of the ultrasonic wave array sensor which is an ultrasonic wave array sensor which is two-dimensionally arranged on the same substrate, Based on the arrangement position of the receiving element, a position calculation unit for obtaining the direction in which the sound source exists with respect to the ultrasonic receiver, and a light or radio wave trigger signal provided on the sound source side of the sound source and the ultrasonic receiver Trigger signal transmitter to transmit and provided on the ultrasonic receiver side A trigger signal receiver that receives the trigger signal, and a control unit that controls the transmission start timing of the trigger signal from the trigger signal transmitter and the transmission start timing of the ultrasonic wave from the sound source. Position detection means comprising distance calculation means for determining the distance between the ultrasonic receiver and the sound source from the relationship between the time when the trigger signal is received by the trigger signal receiver and the time when the ultrasonic wave is received by the receiving element system. It is mounted on a position detection target object that moves on the floor in the building, can generate ultrasonic waves, and has a resonance characteristic Q value of about 1 and a fixed position on the ceiling surface that is the construction surface in the building. There are a plurality of receiving elements that receive an ultrasonic wave transmitted from a sound source and convert the received ultrasonic wave into a received wave signal that is an electric signal and have a resonance characteristic Q value of about 3 to 4. The time difference between the time when the ultrasonic wave is received by each wave receiving element of the ultrasonic wave array sensor which is an ultrasonic wave array sensor which is two-dimensionally arranged on the same substrate, A position calculation unit for obtaining the direction in which the sound source is present with respect to the ultrasonic receiving device based on the arrangement position of the receiving element, and a light or radio wave provided on the ultrasonic receiving device side of the sound source and the ultrasonic receiving device. Trigger signal transmitter for transmitting trigger signals and provided on the sound source side A trigger signal receiver that receives the trigger signal and a control unit that transmits ultrasonic waves from the sound source when the trigger signal is received by the trigger signal receiver, and the position calculation unit is triggered from the trigger signal transmitter. A position detection system comprising distance calculation means for obtaining a distance between an ultrasonic receiving device and a sound source from a relationship between a time when a signal is transmitted and a time when an ultrasonic wave is received by a wave receiving element. There are a plurality of sound sources, a plurality of identification information signal transmitters that are provided on the sound source side of the sound sources and the ultrasonic receiving device and transmit unique identification information signals, respectively, and the ultrasonic receiving device side An identification information signal receiver provided for receiving an identification information signal, wherein an identification information signal transmitter is used as the trigger signal transmitter and the trigger signal is identified using an identification information signal receiver as the trigger signal receiver The control unit controls the position calculation by controlling the transmission start timing of the identification information signal from the identification information signal transmitter and the transmission start timing of the ultrasonic wave from the sound source provided on the sound source side. The unit includes sound source specifying means for individually specifying each sound source based on the identification information signal received by the identification information signal receiving section, and the distance calculating means includes the identification information signal. By the receiving unit and the time of reception of the identification information signal the wave receiving element from the relationship between the time that receives ultrasonic waves according to claim 1, wherein the determining the distance between the sound source and the ultrasonic receiving device Position detection system. 4. The position detection system according to claim 1, wherein a flow line measurement is performed to track the movement of the object using the direction and distance of the sound source at each time when the trigger signal is received . There are a plurality of the sound sources, an identification information signal transmitter that is provided on each sound source side of each of the sound sources and the ultrasonic receiving device and transmits a unique identification information signal, and provided on the ultrasonic receiving device side. An identification information signal receiver for receiving an identification information signal; and a sound source identification means for individually identifying each sound source based on the identification information signal provided on the ultrasonic receiving device side and received by the identification information signal receiver. claim 1 or claim 2 position detection system according to characterized in that it comprises. The sound source includes a support substrate, a heating element layer formed on one surface side of the support substrate, and a heat insulating layer interposed between the support substrate and the heating element layer on the one surface side of the support substrate, The position detection system according to any one of claims 1 to 5 , further comprising an ultrasonic wave generating element that generates an ultrasonic wave in accordance with a temperature change of the heat generating layer accompanying energization of the heat generating layer . The position detecting system according to any one of claims 1 to 6, wherein the wave receiving element includes a capacitive microphone that converts a sound pressure of ultrasonic waves into a change in capacitance . The position detection system according to any one of claims 1 to 7, wherein a distance between centers of the wave receiving elements is set to about 0.5 to 5 times a wavelength of the ultrasonic wave . The position detection system according to claim 1, wherein the wave receiving element is formed using a micromachining technique .

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