Sonication equipment and ultrasound systems

Abstract

A burst drive signal (Sdv) includes a sensor drive period (Tdv) for transmitting a first drive signal (SGD1), and an interval period (Tit) which is provided between adjacent sensor drive periods for transmitting a second drive signal (SGD2), wherein a frequency of the first drive signal lies within a frequency range of a band-pass filter, and a frequency of the second drive signal is different from a resonant frequency of a sensor element and lies outside the frequency range of the band-pass filter.

Description

[Technical Field]

[0001] The present disclosure relates to sonication devices and ultrasound systems. [Background technology]

[0002] Conventionally, ultrasonic systems have been known that measure the distance to an obstacle by measuring the time of flight (TOF) between the generation of a sound wave and the return of the reflected wave from the obstacle. Conventionally, such ultrasonic systems have often been installed in vehicles, and an example thereof is an in-vehicle clearance sonar.

[0003] As an example of an ultrasonic system, Patent Document 1 discloses an ultrasonic system that transmits ultrasonic waves by driving a sensor element (piezoelectric element) based on a burst drive pattern using burst waves with time intervals between them. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-60410 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the ultrasound system of Patent Document 1, an ID is assigned to the ultrasound system by giving characteristics to the ultrasound waves transmitted based on the burst wave interval, burst duration, etc., and the ultrasound system has a self-wave determination function that determines whether a reflected wave (self-wave) of an ultrasound wave transmitted from its own ultrasound system has been received.

[0006] However, in the above ultrasonic system, reverberation waves caused by damped vibration of the sensor element at time intervals in the burst drive pattern are generated in the transmitted ultrasonic waves, and receiving the reflected waves of these reverberation waves can lead to erroneous judgments of the own waves, leaving room for improvement.

[0007] In view of the above circumstances, an object of the present disclosure is to provide an acoustic wave processing device that can suppress erroneous determination of own waves due to the influence of reverberation. [Means for solving the problem]

[0008] For example, the sonic processing device according to the present disclosure includes a drive unit that outputs a burst drive signal to drive a sensor element for transmitting a sonic wave; a received signal output unit that outputs a received signal based on the received sound wave; a bandpass filter to which the received signal is input; a self-wave determination unit that determines whether a received sound wave is a reflected wave based on a sound wave transmitted from an ultrasonic system including its own sound processing device, based on the output of the band-pass filter; and the burst drive signal has a sensor drive period during which a first drive signal is transmitted, and an interval period provided between adjacent sensor drive periods during which a second drive signal is transmitted, the frequency of the first drive signal is within the frequency band of the band-pass filter; The frequency of the second drive signal is different from the resonance frequency of the sensor element and is outside the frequency band of the band-pass filter. [Effects of the Invention]

[0009] According to the sound wave processing device of the present disclosure, it is possible to prevent erroneous determination of the own wave due to the influence of reverberation. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram schematically illustrating an example of a vehicle equipped with an ultrasound system and an object. [Figure 2] FIG. 2 is a diagram showing the configuration of an ultrasound system using an ultrasound processing device according to an exemplary embodiment of the present disclosure. [Figure 3]FIG. 3 is a timing chart showing an example of operation when a sensor driving method according to a comparative example is implemented. [Figure 4] FIG. 4 is a timing chart showing an example of operation when the sensor driving method according to the present disclosure is implemented. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, exemplary embodiments of the present disclosure will be described with reference to the drawings. Note that the ultrasound system according to the embodiments described below is intended to be mounted on a vehicle, as an example, and can be used for functions such as an alarm function, an automatic braking function, and an automatic parking function by measuring the distance between the vehicle and an object.

[0012] <1. Ultrasound system configuration> 1 is a diagram schematically illustrating an example of a vehicle 500 equipped with an ultrasonic system (not shown) described below, and an object (obstacle) 1000. Ultrasonic waves transmitted from the ultrasonic system are reflected by the object 1000 and received as reflected waves by the ultrasonic system. The ultrasonic system measures the distance between the vehicle 500 and the object 1000 based on the time from transmission to reception of the ultrasonic waves. That is, the ultrasonic system measures the distance using a so-called TOF (Time Of Flight) method.

[0013] FIG. 2 is a diagram showing the configuration of an ultrasound system 10 using the ultrasound processing device 1 according to an exemplary embodiment of the present disclosure.

[0014] The ultrasonic system 10 includes an ultrasonic processing device 1, an ultrasonic transmitting / receiving device 5, and a transformer Tr. The ultrasonic transmitting / receiving device 5 is externally connected to the ultrasonic processing device 1 via the transformer Tr. Note that the transformer Tr is not necessarily provided.

[0015] The sound processing device 1 is a semiconductor device that has, integrated on one chip, a DA circuit 2, an analog front end 3, and a digital processing unit 4. The sound processing device 1 also has external terminals T1 to T5 for establishing electrical connection with the outside.

[0016] The DA circuit 2 converts the burst drive signal Sdv output from the drive unit 41 included in the digital processing unit 4 from a digital signal to an analog signal. The DA circuit 2 is connected to the primary side of the transformer Tr via external terminals T1 and T2.

[0017] An ultrasonic transmitter / receiver 5 is connected to the secondary side of the transformer Tr1. The ultrasonic transmitter / receiver 5 has a sensor element (piezoelectric element) (not shown) and transmits and receives ultrasonic waves. In other words, the ultrasonic transmitter / receiver 5 functions as both a sound source and a receiver.

[0018] The DA circuit 2 passes a current through the transformer Tr based on the burst drive signal Sdv generated by the drive unit 41. This drives the sensor element, causing the ultrasonic transmitter / receiver 5 to transmit an ultrasonic wave. That is, the drive unit 41 drives the sensor element based on the burst drive signal Sdv. The configuration of the burst drive signal Sdv will be described later.

[0019] The analog front end 3 (received signal output section) has an LNA (low noise amplifier) ​​31, an LPF (low pass filter) 32, and an A / D converter 33. The primary side of the transformer Tr is connected to the LNA 31 via external terminals T3 and T4. The output of the LNA 31 is input to the A / D converter 33 via the LPF 32.

[0020] The ultrasonic waves are received by the sensor element in the ultrasonic transmitting / receiving device 5, converted into an electric signal, and output as a received signal RS via the transformer Tr and the analog front end 3.

[0021] The digital processing unit 4 has a driving unit 41 , a BPF (band pass filter) 42 , a sensor driving period detection unit 43 , an interval period detection unit 44 , a self-wave determination unit 45 , a TOF measurement unit 46 , and a serial interface 47 .

[0022] The BPF 42 passes only signals in a predetermined frequency band of the received signal RS output from the analog front end 3, and removes signals outside the frequency band.

[0023] The sensor drive period detector 43 detects the sensor drive period based on the output of the BPF 42. More specifically, it detects the number of sensor drive periods. Note that the sensor drive period is a period included in the burst drive signal Sdv, as will be described later, and is a period during which the drive signal is transmitted to drive the sensor element.

[0024] The interval period detection unit 44 detects the interval period based on the output of the BPF 42. More specifically, it detects the length of the interval period. Note that the interval period is a period included in the burst drive signal Sdv, as will be described later, and is provided between adjacent sensor drive periods.

[0025] The own wave determination unit 45 determines whether the received ultrasonic waves are reflected waves (own waves) that have been transmitted from its own ultrasonic system 10 and reflected by an object, based on the detection results of the sensor drive period detection unit 43 and the interval period detection unit 44. By setting parameters such as the number of sensor drive periods and the length of the interval periods in the burst drive signal Sdv, it becomes possible to give characteristics to the transmitted ultrasonic waves and assign an ID to the ultrasonic system 10. The own wave determination unit 45 can determine whether the waves are its own waves by checking whether the detection results of the sensor drive period detection unit 43 and the interval period detection unit 44 match the parameters set in its own ultrasonic system 10 (sonic processing device 1).

[0026] The TOF measurement unit 46 measures the time (TOF) from when an ultrasonic wave is transmitted until when a reflected wave reflected by an object is received, using the counter 461. More specifically, the TOF measurement unit 46 acquires, as measured distance information, the count value from when the drive unit 41 starts to output the burst drive signal Sdv (i.e., when the drive of the sensor element starts) until when the own wave determination unit 45 determines that the wave is its own wave.

[0027] The serial interface 47 is compliant with, for example, DSI3 and communicates with an external ECU (vehicle electronic control unit) (not shown) via an external terminal T5. The acquired count value is sent to the ECU by the serial interface 47.

[0028] <2. Comparative Example> Before describing the sensor driving method according to the present disclosure in the ultrasonic system 10 configured as described above, a sensor driving method according to a comparative example will be described. FIG. 3 is a timing chart showing an example of operation when the sensor driving method according to the comparative example is implemented in the ultrasonic system 10 (FIG. 2). Note that FIG. 3 (and FIG. 4, which will be described later) shows, from the top to bottom, example waveforms of the burst drive signal Sdv, the reflected wave Wr, the sound pressure SPwr (lowest level = 0) of the reflected wave Wr, and the output BPF#OUT of the BPF 42. The reflected wave Wr is a reflected wave based on an ultrasonic wave transmitted from the ultrasonic transmitting / receiving device 5 when the sensor element is driven by the burst drive signal Sdv.

[0029] As shown in Figure 3, the burst drive signal Sdv has a sensor drive period Tdv and an interval period Tit. During the sensor drive period Tdv, a drive signal SGD consisting of a pulse signal (unit pulse wave) is transmitted. The frequency of the drive signal SGD is preferably set to the resonant frequency of the sensor element. This makes it possible to increase the sound pressure of the transmitted ultrasonic waves when the sensor element is driven by the drive signal SGD. Figure 3 shows an example in which the frequency of the drive signal SGD is set to the resonant frequency.

[0030] An interval period Tit is provided between adjacent sensor drive periods Tdv. That is, in the burst drive signal Sdv, the drive signal SGD is transmitted intermittently. In the sensor drive method of the comparative example, no drive signal is transmitted during the interval period Tit.

[0031] In the example of Fig. 3, the number of sensor driving periods Tdv is set to three, and therefore two interval periods Tit are provided. Also, in the example of Fig. 3, the lengths of the two interval periods Tit are set to be the same. However, the number of sensor driving periods Tdv may be set to a number other than three, and when multiple interval periods Tit are provided, some of the interval periods Tit may have different lengths. In this way, by setting the number of sensor driving periods Tdv and the length of the interval periods Tit, it is possible to impart characteristics to the transmitted ultrasonic waves.

[0032] When the sensor element is driven by the burst drive signal Sdv, the transmitted ultrasonic waves are reflected by the object, generating the reflected wave Wr shown in Fig. 3. Here, the reflected wave Wr shown in Fig. 3 (and Fig. 4, which will be described later) is shown as a simplified square wave for convenience, but in reality it is an analog waveform (for example, a sinusoidal waveform) that has the frequency of the square wave shown in the figure and the sound pressure SPwr shown in the figure.

[0033] As shown in Figure 3, the reflected wave Wr has a drive wave W1 corresponding to the drive signal SGD during the sensor drive period Tdv. The drive wave W1 converges to the frequency (=resonance frequency) of the drive signal SGD after the sensor element starts to drive. As the frequency converges, the sound pressure SPwr is maintained at a high level.

[0034] Furthermore, during the interval period Tit, no drive signal is transmitted, but due to the damped vibration of the sensor element, the reflected wave Wr contains a reverberation wave W2. In the reverberation wave W2, the sound pressure SPwr attenuates and the frequency converges to the resonance frequency.

[0035] Here, the resonant frequency (= the frequency of the drive signal SGD) is included in the frequency band of the BPF 42. For example, the resonant frequency is the center frequency of the frequency band. As a result, as shown in FIG. 3, an output signal OUT1 of a resonant frequency appears at the output BPF#OUT of the BPF 42, corresponding to the waveform of the resonant frequency in the drive wave W1. Note that in FIG. 3 (and FIG. 4, which will be described later), the output BPF#OUT is illustrated as a simplified square wave for convenience; in reality, the output BPF#OUT has the frequency of the square wave shown in the figure and a waveform with a sound pressure corresponding to the sound pressure SPwr.

[0036] Furthermore, when the sound pressure SPwr in the reverberation wave W2 is equal to or greater than a certain level, an output signal OUT2 of the resonant frequency appears at the output BPF#OUT. In other words, the waveform of the reverberation wave W2 at the resonant frequency when the sound pressure SPwr is equal to or greater than a certain level cannot be removed by the BPF 42.

[0037] Here, the sensor drive period detection unit 43 detects the number of sensor drive periods by, for example, detecting the number of points where the sound pressure of the output BPF#OUT of the BPF 42 is equal to or higher than a predetermined level. In the example of Fig. 3, the number of sensor drive periods Tdv is set to three, but the detection result of the number of sensor drive periods Tdv based on the output BPF#OUT is detected as five because the output signal OUT2 due to the influence of the reverberation wave W2 is also included in the count. This may cause the own wave determination unit 45 to erroneously determine that the signal is not the own wave.

[0038] Furthermore, the interval period detection unit 44 detects, as an interval period, the length of a period during which the sound pressure level of the output BPF#OUT of the BPF 42 is equal to or lower than a predetermined level. However, in the example of Fig. 3, the period between the output signals OUT1 and OUT2 is detected as an interval period due to the output signal OUT2 being affected by the reverberation wave W2. Because the length of the detected period does not match the length of the set interval period Tit, there is a risk that the own wave determination unit 45 will erroneously determine that the signal is not the own wave.

[0039] As described above, in the comparative example, there is a risk that an erroneous determination of the self-wave may occur due to the influence of reverberation when the sensor element is driven. The sensor driving method according to the present disclosure, which will be described below, is implemented to solve the above-mentioned problems.

[0040] 3. Sensor driving method according to the present disclosure Fig. 4 is a timing chart showing an example of operation when the sensor driving method according to the present disclosure is implemented in the ultrasound system 10 (Fig. 2). In the sensor driving method according to the present disclosure, as shown in Fig. 4, in the burst drive signal Sdv, the first drive signal SGD1 is transmitted during the sensor drive period Tdv, as in the comparative example (Fig. 3), but the second drive signal SGD2 is transmitted during the interval period Tit, unlike the comparative example. That is, in the sensor driving method according to the present disclosure, the first drive signal SGD1, which is the main drive signal, is transmitted intermittently by the burst drive signal Sdv.

[0041] The second drive signal SGD2 is set to a frequency outside the frequency band of the BPF 42. That is, the frequency of the second drive signal SGD2 is set to a frequency different from that of the first drive signal SGD1 (=resonant frequency).

[0042] 4, the frequency of the second drive signal SGD2 is set to a frequency higher than the frequency band of the BPF 42, but it may also be set to a frequency lower than that frequency band. However, setting the frequency higher than the frequency band of the BPF 42 shortens the interval period Tit for the same number of unit pulse waves constituting the second drive signal SGD2. Therefore, the overall length of the burst drive signal Sdv can be shortened.

[0043] In this case, as shown in Figure 4, in the reflected wave Wr, a drive wave W1 appears in response to the first drive signal SGD1, as in the comparative example. However, because the second drive signal SGD2 has a different resonant frequency, the sound pressure of the ultrasonic waves transmitted by driving the sensor element is small (almost zero). Therefore, as shown in Figure 4, in the reflected wave Wr, during the period (interval period Tit) corresponding to the second drive signal SGD2, no waveform appears after the drive wave W3 when the sound pressure SPwr attenuates (sound pressure SPwr = 0). Note that the frequency of the drive wave W3 is the frequency of the second drive signal SGD2.

[0044] 4, an output signal OUT1 corresponding to the drive wave W1 appears at the output BPF#OUT of the BPF 42, as in the comparative example. However, the drive wave W3 generated in the reflected wave Wr during the interval period Tit has a frequency outside the frequency band of the BPF 42, so the drive wave W3 is removed by the BPF 42 and does not appear at the output BPF#OUT. Furthermore, since no waveform appears after the drive wave W3 during the interval period Tit, no waveform appears at the output BPF#OUT either.

[0045] In this way, in the sensor driving method according to the present disclosure, the second drive signal SGD2 set to a frequency different from the resonant frequency is transmitted during the interval period Tit, so that no waveform is generated during the interval period Tit in the reflected wave Wr, or even if a waveform is generated, it is at a frequency outside the frequency band of the BPF 42, so that no waveform is generated during the interval period Tit in the output BPF#OUT. Therefore, the detection results of the sensor driving period detection unit 43 and the interval period detection unit 44 match the settings, so that the own wave is determined to be the own wave by the own wave determination unit 45, and erroneous determination can be avoided.

[0046] It should be noted that the interval period Tit is preferably set to a length equal to or greater than four unit pulse waves constituting the second drive signal SGD2, taking into consideration the ability of the sensor element to follow the second drive signal SGD2.

[0047] <4.Other> Although exemplary embodiments have been described above, the embodiments can be modified in various ways within the spirit and scope of the present invention.

[0048] For example, an ultrasonic wave transmitting device for transmitting waves may be connected to the DA circuit 2, and an ultrasonic wave receiving device for receiving waves, separate from the ultrasonic wave transmitting device, may be connected to the analog front end 3. In other words, the sound source and the receiving unit do not have to be the same device.

[0049] Furthermore, an ultrasonic system including an ultrasonic processing device can be mounted on a moving object other than a vehicle, for example, on an unmanned transport robot that transports luggage, a service robot, etc. Furthermore, the ultrasonic system may be mounted on a stationary object instead of a moving object.

[0050] <5. Notes> As described above, the sonic processing device (1) according to one aspect of the present disclosure includes: a drive unit (41) that outputs a burst drive signal (Sdv) to drive a sensor element for transmitting sound waves; a received signal output unit (3) that outputs a received signal (RS) based on the received sound wave; a bandpass filter (42) to which the received signal is input; a self-wave determination unit (45) that determines, based on the output of the bandpass filter, whether the received sound wave is a reflected wave based on a sound wave transmitted from an ultrasonic system (10) including its own sound processing device; and the burst drive signal has a sensor drive period (Tdv) during which a first drive signal (SGD1) is transmitted, and an interval period (Tit) provided between adjacent sensor drive periods during which a second drive signal (SGD2) is transmitted, the frequency of the first drive signal is within the frequency band of the band-pass filter; The frequency of the second drive signal is different from the resonance frequency of the sensor element and is outside the frequency band of the band-pass filter (first configuration).

[0051] In the first configuration, the frequency of the second drive signal may be higher than the frequency band of the band-pass filter (second configuration).

[0052] In the first or second configuration, the frequency of the first drive signal may be the resonance frequency (third configuration).

[0053] Furthermore, in any one of the first to third configurations, the interval period may have a length equal to or greater than four waves of the unit waveform that constitutes the second drive signal (fourth configuration).

[0054] Furthermore, in any of the above first to fourth configurations, a sensor driving period detection unit (43) may be further provided that detects the number of the sensor driving periods based on the output of the bandpass filter, and the self-wave determination unit may be configured to perform self-wave determination based on the detection result of the sensor driving period detection unit (fifth configuration).

[0055] Furthermore, in any of the first to fifth configurations, the present invention may further include an interval period detection unit (44) that detects the length of the interval period based on the output of the bandpass filter, and the own wave determination unit may be configured to perform own wave determination based on the detection result of the interval period detection unit (sixth configuration).

[0056] Furthermore, in the sixth configuration, the interval periods may be set to have different lengths (seventh configuration).

[0057] Furthermore, in any of the first to seventh configurations, the configuration may further include a DA circuit (2) that drives the sensor element by D / A converting the burst drive signal output from the drive unit (eighth configuration).

[0058] In addition, in any of the first to eighth configurations, the received signal output unit may be configured to have an LNA (low noise amplifier) ​​(31), an LPF (low pass filter) (32) placed in a stage subsequent to the LNA, and an A / D converter (33) placed in a stage subsequent to the LPF (ninth configuration).

[0059] An ultrasonic system (10) according to one aspect of the present disclosure includes an ultrasonic processing device having any one of the first to ninth configurations described above, and a sensor element driven by the ultrasonic processing device.

[0060] The ultrasound system is, for example, for use in a vehicle. [Industrial Applicability]

[0061] The present disclosure can be used, for example, in an in-vehicle ultrasound system. [Explanation of symbols]

[0062] 1. Sonication device 2. DA circuit 3 Analog Front End 4 Digital Processing Section 5. Ultrasonic transmitter / receiver 10 Ultrasound System 31 LNA 32 LPF 33 A / D converter 41 Drive unit 42 BPF 43 Sensor drive period detection unit 44 Interval period detection unit 45 Own wave determination section 46 TOF measurement unit 47 Serial Interface 461 counters 500 vehicles 1000 objects T1~T5 external terminals

Claims

1. a drive unit that outputs a burst drive signal to drive a sensor element for transmitting sound waves; a received signal output unit that outputs a received signal based on the received sound wave; a bandpass filter to which the received signal is input; a self-wave determination unit that determines whether a received sound wave is a reflected wave based on a sound wave transmitted from an ultrasonic system including its own sound processing device, based on the output of the band-pass filter; and the burst drive signal has a sensor drive period during which a first drive signal is transmitted, and an interval period provided between adjacent sensor drive periods during which a second drive signal is transmitted, the frequency of the first drive signal is within the frequency band of the band-pass filter, An acoustic wave processing device, wherein the frequency of the second drive signal is different from the resonant frequency of the sensor element and is outside the frequency band of the bandpass filter.

2. The sonic processing device of claim 1 , wherein the frequency of the second drive signal is higher than the frequency band of the bandpass filter.

3. The sonic processing device of claim 1 , wherein the frequency of the first drive signal is the resonant frequency.

4. The ultrasonic wave processing device according to claim 1 , wherein the interval period has a length equal to or greater than four waves of the unit waveform that constitutes the second drive signal.

5. a sensor driving period detection unit that detects the number of the sensor driving periods based on an output of the band pass filter; The ultrasonic processing device according to claim 1 , wherein the self-wave determining unit performs the self-wave determination based on the detection result of the sensor drive period detecting unit.

6. further comprising an interval period detection unit that detects the length of the interval period based on the output of the band-pass filter; The ultrasonic processing device according to claim 1 , wherein the self-wave determining unit performs the self-wave determination based on a detection result of the interval period detecting unit.

7. The sonic processing device according to claim 6 , wherein the interval periods can be set to have different lengths.

8. The ultrasonic processing device according to claim 1 , further comprising a DA circuit that drives the sensor element by D / A converting the burst drive signal output from the drive unit.

9. 2. The ultrasonic processing device according to claim 1, wherein the received signal output unit has an LNA (low noise amplifier), an LPF (low pass filter) arranged in a stage subsequent to the LNA, and an A / D converter arranged in a stage subsequent to the LPF.

10. 10. An ultrasound system comprising a sonication device according to any one of claims 1 to 9 and a sensor element driven by the sonication device.

11. The ultrasound system of claim 10, which is mounted on a vehicle.

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