Ultrasonic wave generation device, vibrator, and object detection device

Abstract

An ultrasonic wave generating device according to an embodiment of the present invention is provided with: a vibrator; the ultrasonic transducer is provided with a piezoelectric body which generates ultrasonic waves due to piezoelectric effect vibration when an AC voltage is applied, two or more electrodes which are provided at different heights on the surface of the piezoelectric body, and a counter electrode which is provided at a position facing the two or more electrodes. And a control unit that, when receiving an ultrasonic generation instruction including information on the directivity of the generated ultrasonic waves, performs control such that, from the two or more electrodes and the counter electrode, a combination of a voltage application electrode and a ground electrode corresponding to the directivity in the ultrasonic generation instruction is selected, and the selected combination of the voltage application electrode and the ground electrode corresponds to the directivity in the ultrasonic generation instruction. The ultrasonic wave generator is configured to generate ultrasonic waves by applying an AC voltage to the voltage application electrode, the voltage application electrode being an electrode to which the AC voltage is applied, and the ground electrode being an electrode having a ground potential.

Description

Technical Field

[0001] The present disclosure relates to an ultrasonic wave generating device, a vibrator, and an object detecting device. Background Art

[0002] Conventionally, there is a technique for applying an alternating voltage to a piezoelectric body to vibrate the piezoelectric effect and generate ultrasonic waves. In addition, if object detection is to be performed based on the reflected waves of the generated ultrasonic waves, it is of great significance to change the directivity of the ultrasonic waves in the height direction (vertical direction).

[0003] In order to change the directivity of ultrasonic waves in the height direction, there is a method of using a plurality of transducers, for example.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2012-249950

[0005] Patent Document 2: Japanese Patent Application Publication No. 2009-21723

[0006] However, if a plurality of transducers are used to change the directivity of ultrasonic waves in the height direction, there is a problem that the cost becomes high. Summary of the invention

[0007] Therefore, one of the objects of the present disclosure is to provide an ultrasonic wave generating device, a transducer, and an object detecting device capable of changing the directivity of generated ultrasonic waves in the height direction at low cost.

[0008] An ultrasonic generating device as an example of the present disclosure comprises: a vibrator comprising a piezoelectric body that generates ultrasonic waves by vibrating due to the piezoelectric effect when an alternating voltage is applied, and two or more electrodes arranged at positions with different heights on the surface of the piezoelectric body and an opposing electrode arranged at a position opposite to the two or more electrodes; and a control unit that, upon receiving an ultrasonic generation instruction including information on the directivity of the generated ultrasonic wave, performs the following control: selects a combination of a voltage applying electrode and a ground electrode corresponding to the directivity in the ultrasonic generation instruction from the two or more electrodes and the opposing electrode, and applies an alternating voltage to the voltage applying electrode to generate ultrasonic waves, wherein the voltage applying electrode is an electrode to which the alternating voltage is applied, and the ground electrode is an electrode set to a ground potential.

[0009] With such a configuration, the directivity of the ultrasonic wave in the height direction can be changed by a single transducer, so the cost is low.

[0010] In addition, a vibrator as an example of the present invention comprises: a piezoelectric body, which vibrates due to the piezoelectric effect to generate ultrasonic waves when an AC voltage is applied; two or more electrodes arranged at different heights on the surface of the above-mentioned piezoelectric body and an opposing electrode arranged at a position opposite to the above-mentioned two or more electrodes, wherein the directivity of the ultrasonic waves generated by the above-mentioned two or more electrodes and the above-mentioned opposing electrode is different depending on the combination of the voltage applying electrode and the ground electrode selected, the above-mentioned voltage applying electrode is an electrode to which an AC voltage is applied, and the above-mentioned ground electrode is an electrode set to a ground potential.

[0011] With such a configuration, the directivity of the ultrasonic wave in the height direction can be changed by a single transducer, so the cost is low.

[0012] In addition, an object detection device as an example of the present disclosure includes: a transmitting unit that transmits ultrasonic waves through a vibrator; a receiving unit that receives reflected waves of the ultrasonic waves through the vibrator; and a control unit. The vibrator includes: a piezoelectric body that generates ultrasonic waves by vibrating due to the piezoelectric effect when an AC voltage is applied; and two or more electrodes provided at positions with different heights on the surface of the piezoelectric body and an opposing electrode provided at a position opposite to the two or more electrodes. When the control unit receives an ultrasonic generation instruction including information on the directivity of the generated ultrasonic wave, the control unit selects a combination of a voltage applying electrode and a ground electrode corresponding to the directivity in the ultrasonic generation instruction from the two or more electrodes and the opposing electrode, and applies an AC voltage to the voltage applying electrode to generate ultrasonic waves, wherein the voltage applying electrode is an electrode to which the AC voltage is applied, and the ground electrode is an electrode set to a ground potential.

[0013] With such a configuration, the directivity of the ultrasonic wave in the height direction can be changed by a single transducer, so the cost is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a schematic diagram showing the appearance of a vehicle equipped with the object detection system according to the embodiment, as viewed from above.

[0015] Figure 2 It is a block diagram schematically showing a general hardware configuration of an ECU and an object detection device according to the embodiment.

[0016] Figure 3 It is a schematic diagram showing an overview of a vibrator according to an embodiment.

[0017] Figure 4 This is a diagram for explaining the directivity of ultrasonic waves generated from the transducer according to the embodiment.

[0018] Figure 5 This is an explanatory diagram of the detection range of the ultrasonic wave generated by the transducer according to the embodiment.

[0019] Figure 6 This is an explanatory diagram of an overview of a technique used by the object detection device according to the embodiment to detect the distance to an object.

[0020] Figure 7 It is a block diagram schematically showing the detailed configuration of the object detection device according to the embodiment.

[0021] Figure 8 It is a diagram showing directivity correspondence information according to an embodiment.

[0022] Fig. 9 This is a flowchart showing a first process executed by the object detection system according to the embodiment.

[0023] Fig.10 : is a flowchart showing the second process executed by the object detection system according to the embodiment.

[0024] Fig.11 : is a flowchart showing the third process executed by the object detection system according to the embodiment. DETAILED DESCRIPTION

[0025] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. The configuration of the embodiments described below and the functions and effects brought about by the configurations are merely examples, and the present invention is not limited to the following descriptions.

[0026] Figure 1 The object detection system of the embodiment is a schematic diagram of the appearance of a vehicle equipped with an object detection system according to the embodiment, viewed from above. The object detection system according to the embodiment detects objects (such as the following) existing in the surroundings by transmitting and receiving ultrasonic waves and utilizing the time difference between the transmitted and received signals. Figure 2 An on-board sensor system that provides information related to the obstacle O) shown.

[0027] More specifically, if Figure 1 As shown, the object detection system of the embodiment includes an ECU (Electronic Control Unit) 100 as a vehicle-mounted control device and object detection devices 201 to 204 as vehicle-mounted sonars. The ECU 100 is mounted inside a four-wheeled vehicle 1 including a pair of front wheels 3F and a pair of rear wheels 3R, and the object detection devices 201 to 204 are mounted on a housing of the vehicle 1.

[0028] exist Figure 1 In the example shown, the object detection devices 201 to 204 are provided at different positions at the rear end portion (rear bumper) of the vehicle body 2 as the outer shell of the vehicle 1, but the installation positions of the object detection devices 201 to 204 are not limited to Figure 1For example, the object detection devices 201 to 204 may be provided at the front end (front bumper) of the vehicle body 2, at the side of the vehicle body 2, or at two or more of the rear end, the front end, and the side.

[0029] In addition, in the embodiment, the hardware configuration and functions of the object detection devices 201 to 204 are the same. Therefore, in order to simplify the description, the object detection devices 201 to 204 are collectively referred to as "object detection devices 200" (an example of ultrasonic wave generating devices). In addition, in the embodiment, the number of object detection devices 200 is not limited to Figure 1 4 shown.

[0030] Figure 2 This is a block diagram schematically showing a general hardware configuration of ECU 100 and object detection device 200 according to the embodiment.

[0031] like Figure 2 As shown, the ECU 100 has the same hardware configuration as a general computer. More specifically, the ECU 100 includes an input / output device 110 , a storage device 120 , and a processor 130 .

[0032] The input / output device 110 is used to realize communication between the ECU 100 and the external ( Figure 1 In the example shown, an interface for sending and receiving information between the object detection device 200).

[0033] The storage device 120 includes a main storage device such as a ROM (Read Only Memory) or a RAM (Random Access Memory), and / or an auxiliary storage device such as a HDD (Hard Disk Drive) or a SSD (Solid State Drive).

[0034] The processor 130 is responsible for various processes executed in the ECU 100. The processor 130 includes, for example, a computing device such as a CPU (Central Processing Unit). The processor 130 realizes various functions by reading out a computer program stored in the storage device 120 and executing the program.

[0035] On the other hand, Figure 2 As shown, the object detection device 200 includes a transceiver 210 and a control unit 220 .

[0036] The transceiver 210 includes a vibrator 211 (an example of an ultrasonic sensor) formed of a piezoelectric element or the like and a switching unit 212 , and transmits and receives ultrasonic waves through the vibrator 211 .

[0037] More specifically, the transceiver 210 transmits ultrasonic waves generated by the vibration of the vibrator 211 as transmission waves, and receives vibrations of the vibrator 211 caused by the ultrasonic waves transmitted as the transmission waves being reflected by an external object as reception waves (reflection waves). Figure 2 In the illustrated example, an obstacle O provided on the road surface RS is illustrated as an object that reflects ultrasonic waves from the transceiver 210 .

[0038] here, Figure 3 1 is a schematic diagram showing an overview of the vibrator 211 according to the embodiment. The following description is based on the assumption that the vibrator 211 is installed in the vehicle 1. The vibrator 211 includes a front electrode 4, a wiring 5, a piezoelectric body 6, a rear electrode 7, and a wiring 8.

[0039] The front electrode 4 is an example of two or more electrodes provided at different heights (vertical positions) on the surface of the piezoelectric body 6. The front electrodes 4a and 4b are provided as the front electrode 4. The front electrodes 4a and 4b are electrically insulated from each other.

[0040] The wiring 5 includes a wiring 5 a connected to the front electrode 4 a and a wiring 5 b connected to the front electrode 4 b .

[0041] When an AC voltage is applied to the piezoelectric body 6, it vibrates due to the piezoelectric effect and generates ultrasonic waves.

[0042] The rear electrode 7 is a counter electrode provided on the surface of the piezoelectric body 6 at a position facing the front electrodes 4 a and 4 b .

[0043] The wiring 8 is connected to the rear electrode 7 .

[0044] The processor 223 selects a voltage application electrode and a ground electrode from the front electrodes 4a, 4b and the rear electrode 7, and controls the directivity of the generated ultrasonic waves by adjusting the frequency, phase, and amplitude of the applied AC voltage (described in detail later).

[0045] return Figure 2 The control unit 220 has the same hardware configuration as a general computer. More specifically, the control unit 220 includes an input / output device 221 , a storage device 222 , and a processor 223 .

[0046] The input / output device 221 is used to realize the communication between the control unit 220 and the external ( Figure 1 In the example shown, it is an interface for sending and receiving information between ECU 100 and transceiver 210).

[0047] The storage device 222 includes a main storage device such as a ROM and a RAM, and / or an auxiliary storage device such as a HDD and a SSD. The storage device 222 stores, for example, directivity correspondence information 230. The directivity correspondence information 230 is an example of correspondence relationship information of a combination of an electrode to which an AC voltage is applied, i.e., a voltage applying electrode, and an electrode to which a ground potential is set, i.e., a ground electrode, among the front electrodes 4a and 4b and the rear electrode 7, the frequency, phase, and amplitude of the applied AC voltage, and the directivity of the generated ultrasonic wave. In addition, the frequency, phase, and amplitude are not all necessary, and some or all of them may be absent.

[0048] here, Figure 8 : is a diagram showing the directivity corresponding information 230 of the implementation method. In the directivity corresponding information 230, according to the directivity information, a correspondence is established between the combination of the voltage applying electrode and the grounding electrode, and the frequency, phase, and amplitude of the applied AC voltage, wherein the above-mentioned directivity information is information related to the output direction and diffusion mode of the ultrasonic wave. For example, if the combination of the voltage applying electrode and the grounding electrode is different, the voltage application method for the piezoelectric body 6 is different, and the place where the piezoelectric body 6 vibrates is different, so the directivity of the ultrasonic wave generated from the piezoelectric body 6 is also different. In addition, the grounding electrode can be either multiple or one. In addition, the electrode that is neither the voltage applying electrode nor the grounding electrode is insulated. In addition, the directivity of the ultrasonic wave generated from the piezoelectric body 6 is also different according to the frequency, phase, and amplitude of the applied AC voltage.

[0049] In addition, the output direction of the ultrasonic wave generated by the vibrator 211 is approximately Figure 3 The direction indicated by the reference numeral D in the figure. Here, Figure 4 This is an explanatory diagram of the directivity of the ultrasonic wave generated from the vibrator of the embodiment. Depending on the combination of the voltage applying electrode and the ground electrode, the frequency, phase, and amplitude of the applied AC voltage, the output direction of the ultrasonic wave generated from the piezoelectric body 6 can be changed to various directions in the height direction as shown by the reference numerals D1 to D3. In addition, the diffusion mode of the ultrasonic wave can also be changed in various ways. Moreover, for example, it can be made in advance by experiment. Figure 8 Directivity correspondence information 230 as shown.

[0050] return Figure 2 The processor 223 is responsible for various processes executed in the control unit 220. The processor 223 includes a computing device such as a CPU. The processor 223 realizes various functions by reading and executing a computer program stored in the storage device 222.

[0051] For example, when the processor 223 receives an ultrasonic generation indication including information on the directionality of the generated ultrasonic wave from the ECU 100, the processor 223 refers to the directionality corresponding information 230, selects a combination of a voltage applying electrode and a ground electrode corresponding to the directionality in the ultrasonic generation indication from the front electrodes 4a, 4b and the rear electrode 7, and further determines the frequency, phase, and amplitude, and applies an AC voltage to the voltage applying electrode to generate ultrasonic waves, wherein the voltage applying electrode is an electrode to which an AC voltage is applied, and the ground electrode is an electrode set to a ground potential.

[0052] In addition, the processor 223 calculates the distance to the object that reflected the ultrasonic wave based on the timing of the ultrasonic wave transmitted by the transmitting unit and the timing of the reflected wave of the ultrasonic wave received by the receiving unit. Furthermore, when the distance changes with the passage of time, the processor 223 changes the directivity in the height direction of the ultrasonic wave transmitted by the transmitting unit based on the directivity change information that sets the degree of change in the height direction of the directivity according to the distance (described in detail later).

[0053] In addition, the processor 223 changes the directivity in the height direction of the ultrasonic wave transmitted by the transmitting unit, and acquires change information of the intensity of the reflected wave, and calculates the height of the object reflecting the ultrasonic wave based on the change information (details will be described later).

[0054] In addition, when determining the combination of a voltage applying electrode and a grounding electrode, the switching unit 212 switches the wirings 5a, 5b, and 8 corresponding to the voltage applying electrode to the power supply based on instructions from the processor 223, switches the wirings corresponding to the grounding electrode to the ground, and switches the other wirings to an insulated state.

[0055] The object detection device 200 of the embodiment detects the distance to the object by a technique called the TOF (Time Of Flight) method. The TOF method is a technique for calculating the distance to the object by taking into account the difference between the timing when the transmission wave is transmitted (more specifically, the start of transmission) and the timing when the reception wave is received (more specifically, the start of reception).

[0056] here, Figure 5 This is an explanatory diagram of the detection range of ultrasonic waves generated by the transducer 211 of the embodiment. When the transceiver 210 is installed in front of the vehicle 1, the detection range of ultrasonic waves generated by the transducer 211 can be switched in the height direction as shown in the regions R1 and R2.

[0057] in addition, Figure 6 2 is an explanatory diagram of the outline of the technology used by the object detection device 200 of the embodiment to detect the distance to the object. More specifically, Figure 6This is a diagram schematically and exemplarily showing the time change of the signal level (for example, amplitude) of the ultrasonic wave transmitted and received by the object detection device 200 according to the embodiment. Figure 6 In the graph shown, the horizontal axis corresponds to time, and the vertical axis corresponds to the signal level of a signal transmitted and received by the object detection device 200 via the transceiver 210 (transducer 211 ).

[0058] exist Figure 6 In the graph shown, the solid line L11 represents the signal level of the signal transmitted and received by the object detection device 200, in other words, represents an example of an envelope curve of the time change of the degree of vibration of the vibrator 211. From the solid line L11, it can be read that the vibrator 211 is driven to vibrate for a time Ta from the timing t0, and the transmission of the transmission wave is completed at the timing t1. Thereafter, during the time Tb until the timing t2, the vibration of the vibrator 211 due to inertia continues to decay. Therefore, at Figure 6 In the diagram shown, the time Tb corresponds to the so-called reverberation time.

[0059] The solid line L11 shows that at time t4, when time Tp has passed since the time t0 when the transmission of the transmission wave was started, the vibration level of the vibrator 211 reaches a peak value exceeding a predetermined threshold value Th1 indicated by the dashed line L21. The threshold value Th1 is used to identify that the vibration of the vibrator 211 is caused by the object (e.g. Figure 2 Is it caused by the received wave of the transmitted wave reflected by the obstacle (O) shown in the figure, or by the received wave of the object outside the detection object (such as Figure 2 The predetermined value is caused by the received wave of the transmitted wave reflected and returned by the road surface RS) shown.

[0060] also, Figure 6 Although the example in which the threshold value Th1 is set to a constant value that does not change regardless of the passage of time is shown, in the embodiment, the threshold value Th1 may be set to a value that changes with the passage of time.

[0061] Here, vibrations with a peak value exceeding the threshold value Th1 can be considered to be caused by a received wave that is a transmitted wave reflected and returned by an object to be detected. On the other hand, vibrations with a peak value below the threshold value Th1 can be considered to be caused by a received wave that is a transmitted wave reflected and returned by an object other than the object to be detected.

[0062] Therefore, it can be understood from the solid line L11 that the vibration of the transducer 211 at the timing t4 is also caused by the reception wave of the transmission wave reflected and returned by the object to be detected.

[0063] In the solid line L11, the vibration of the oscillator 211 attenuates after timing t4. Therefore, timing t4 corresponds to the timing when the reception of the reception wave as the transmission wave reflected and returned by the object to be detected is completed, in other words, the timing when the transmission wave last transmitted at timing t1 is returned as the reception wave.

[0064] In addition, in the solid line L11, the timing t3, which is the starting point of the peak at the timing t4, corresponds to the timing of the start of the reception of the received wave of the transmission wave reflected and returned by the object to be detected, in other words, the timing of the transmission wave initially transmitted at the timing t0 returning as the received wave. Therefore, in the solid line L11, the time ΔT between the timing t3 and the timing t4 is equal to the time Ta, which is the transmission time of the transmission wave.

[0065] Based on the above, in order to obtain the distance to the object to be detected by the TOF method, it is necessary to obtain the time Tf between the timing t0 when the transmission wave starts to be transmitted and the timing t3 when the reception wave starts to be received. This time Tf can be obtained by subtracting the time ΔT equal to the time Ta as the transmission time of the transmission wave from the time Tp as the difference between the timing t0 and the timing t4 when the signal level of the reception wave reaches a peak value exceeding the threshold Th1.

[0066] In addition, when investigating whether the object reflecting the ultrasonic wave is the object to be detected (for example Figure 2 Obstacles (shown as O) or objects outside the detection target (such as Figure 2 There are cases where it is desired to change the directivity of the ultrasonic wave generated from the transducer 211 in the height direction, for example, when the road surface RS is shown.

[0067] However, if a plurality of ultrasonic sensors are used to control the directivity of ultrasonic waves, there is a problem that the cost increases. Therefore, in the embodiment, the directivity of ultrasonic waves is controlled by one ultrasonic sensor (transducer 211), thereby achieving low cost.

[0068] In addition, Figure 6 In the figure, the solid line L11 corresponds to the detection range of the transceiver 210. Figure 5 In addition, the dotted line L12 corresponds to the detection range of the transceiver 210. Figure 5 Thus, by changing the directivity of the height direction of the generated ultrasonic wave, the signal level of the reflected wave of the object changes, thereby improving the detection accuracy of the object or calculating the height of the object.

[0069] Figure 7 2 is a block diagram schematically showing a detailed structure of the object detection device 200 according to the embodiment. Figure 7In the figure, the configuration of the transmission side (transmission unit) and the configuration of the reception side (reception unit) are separated, but such a diagram is only for the convenience of explanation. Therefore, in the embodiment, as described above, both the transmission of the transmission wave and the reception of the reception wave are realized by one transceiver 210. However, the technology of the embodiment can also be applied to the configuration in which the configuration of the transmission side and the configuration of the reception side are separated.

[0070] In addition, in an embodiment, Figure 7 At least a part of the configuration shown is implemented as a result of cooperation between hardware and software, more specifically, as a result of processor 223 of object detection device 200 reading a computer program from storage device 222 and executing it. However, in the embodiment, Figure 7 At least a part of the configuration shown may be realized by dedicated hardware (circuitry).

[0071] First, the configuration of the transmission side of object detection device 200 will be briefly described.

[0072] like Figure 7 As shown, the object detection device 200 includes a transmission control unit 430, a wave transmitter 411, a code generation unit 412, a carrier output unit 413, a multiplier 414, and an amplifier circuit 415 as a configuration on the transmission side.

[0073] The wave transmitter 411 is constituted by the above-mentioned oscillator 211 , and transmits a transmission wave corresponding to the transmission signal output (amplified) from the amplifier circuit 415 via the oscillator 211 .

[0074] Here, in the embodiment, the wave transmitter 411 encodes the transmission wave into identification information including a predetermined code length based on the configuration described below and transmits it.

[0075] The code generation unit 412 generates a pulse signal corresponding to a code of a bit string, the bit string including, for example, a bit sequence of 0 or 1. In addition, the length of the bit string corresponds to the code length of the identification information given to the transmission signal. The code length is set, for example, to enable mutual identification from Figure 1 The lengths of the transmission waves transmitted by the four object detection devices 200 are shown.

[0076] The carrier output unit 413 outputs a carrier wave of a signal to be provided with identification information. For example, the carrier wave output unit 413 outputs a sine wave of a predetermined frequency as a carrier wave.

[0077] The multiplier 414 modulates the carrier wave so as to give identification information by multiplying the output from the code generation unit 412 and the output from the carrier wave output unit 413. Then, the multiplier 414 outputs the modulated carrier wave given the identification information as a transmission signal that is the source of the transmission wave to the amplifier circuit 415. In addition, in the embodiment, the modulation method can use a single or a combination of two or more well-known modulation methods such as an amplitude modulation method and a phase modulation method.

[0078] The amplifier circuit 415 amplifies the transmission signal output from the multiplier 414 , and outputs the amplified transmission signal to the wave transmitter 411 .

[0079] In addition, please refer to Figure 3 When receiving an ultrasonic wave generation instruction including information on the directivity of the generated ultrasonic wave from the ECU 100, the transmission control unit 430 (processor 223) refers to the directivity corresponding information 230, selects a combination of a voltage application electrode and a ground electrode corresponding to the directivity in the ultrasonic wave generation instruction from the electrodes of the front electrodes 4a, 4b and the rear electrode 7, and determines the frequency, phase, and amplitude. Furthermore, the transmission control unit 430 controls the switching unit 212 based on the combination of the voltage application electrode and the ground electrode in the wave transmitter 411 (vibrator 211), switches the wiring corresponding to the voltage application electrode among the wirings 5a, 5b, and 8 to the power supply, switches the wiring corresponding to the ground electrode to the ground, and switches the other wirings to be insulated.

[0080] Through such a configuration, in an embodiment, it is possible to use the transmission control unit 430, the switching unit 212, the code generation unit 412, the carrier output unit 413, the multiplier 414, the amplifier circuit 415 and the wave transmitter 411 to transmit a transmission wave (ultrasonic wave) assigned with specified identification information and control the directionality of the transmission wave.

[0081] Next, the configuration of the receiving side of object detection device 200 will be briefly described.

[0082] like Figure 7 As shown, the object detection device 200 includes a wave receiver 421, an amplifier circuit 422, a filter processing unit 423, a correlation processing unit 424, an envelope processing unit 425, a threshold processing unit 426, and a detection processing unit 427 as a receiving side configuration.

[0083] The wave receiver 421 is constituted by the above-mentioned transducer 211, and receives the transmission wave reflected by the object as a reception wave through the transducer 211.

[0084] The amplifier circuit 422 amplifies the reception signal which is a signal corresponding to the reception wave received by the wave receiver 421 .

[0085] The filter processing unit 423 performs a filter process on the received signal amplified by the amplifier circuit 422 to reduce noise. In addition, in an embodiment, the filter processing unit 423 may obtain information related to the frequency of the transmitted signal, and further perform a frequency correction such as matching the received signal with the frequency of the transmitted signal (for example, correction using a bandpass filter that allows a specific frequency to pass, correction for frequency conversion caused by Doppler shift, etc.).

[0086] The correlation processing unit 424 obtains a correlation value corresponding to the similarity of the identification information of the transmission wave and the reception wave based on the transmission signal obtained from the transmission side configuration and the reception signal after the filtering process of the filtering processing unit 423. The correlation value can be obtained based on a well-known correlation function or the like.

[0087] The envelope processing unit 425 obtains the envelope of the waveform of the signal corresponding to the correlation value acquired by the correlation processing unit 424 .

[0088] The threshold value processing unit 426 compares the value of the envelope obtained by the envelope processing unit 425 with a predetermined threshold value.

[0089] The detection processing unit 427 determines the timing when the signal level of the received wave reaches a peak value exceeding the threshold value based on the comparison result of the threshold processing unit 426 ( Figure 6 At the timing t4 shown in the figure, the distance to the object is detected by the TOF method.

[0090] According to the above configuration, the object detection system of the embodiment performs the following Fig. 9 Processing as shown. Fig. 9 The series of processing shown is repeatedly executed in, for example, a predetermined control cycle. Fig. 9 This is a flowchart showing a first process executed by the object detection system according to the embodiment.

[0091] like Fig. 9 As shown, first, in S11, the sending control unit 430 ( Figure 7 ) When an ultrasonic generation indication including information on the directionality of the generated ultrasonic wave is received from ECU 100, a combination of a voltage application electrode and a ground electrode corresponding to the directionality in the ultrasonic generation indication is selected from the electrodes of the front electrodes 4a, 4b and the rear electrode 7 with reference to the directionality corresponding information 230, and the switching unit 212 is controlled according to the combination to switch the wiring corresponding to the voltage application electrode among the wirings 5a, 5b, and 8 to the power supply, and to switch the wiring corresponding to the ground electrode to the ground, and to switch the other wirings to an insulated state.

[0092] Next, in S12, the wave transmitter 411 of the object detection device 200 transmits a transmission wave to which predetermined identification information is given. At this time, the frequency, phase, and amplitude corresponding to the ultrasonic wave generation instruction in the directivity corresponding information 230 are used.

[0093] Next, in S13, the wave receiver 421 of the object detection device 200 receives the reflected wave (received wave) corresponding to the transmission wave transmitted in S12. Furthermore, the correlation processing unit 424 of the object detection device 200 obtains a correlation value corresponding to the similarity of the identification information of the transmission wave and the reception wave under the control of the ECU 100, for example.

[0094] Next, in S14 , after the processing by the envelope processing unit 425 and the processing by the threshold processing unit 426 , the detection processing unit 427 detects the distance to the object by the TOF method.

[0095] Thus, according to the object detection device 200 of this embodiment, using Figure 3 The vibrator 211 of the structure shown in the figure selects the combination of the voltage application electrode and the ground electrode in the front electrodes 4a, 4b and the rear electrode 7. In addition, by adjusting the frequency, phase, and amplitude, the directivity of the height direction of the ultrasound wave can be changed by a single vibrator 211, so the cost is low. In other words, the vibrator needs to have a size larger than the specified size in order to vibrate, but in the prior art, when multiple vibrators are used to control the directivity of the height direction of the ultrasound wave, multiple vibrators of a size larger than the specified size need to be used, which increases the cost. On the other hand, according to the technology of this embodiment, the directivity of the ultrasound wave can be controlled by a single vibrator 211, so the cost is low.

[0096] In addition, by changing the directivity of the height direction of the generated ultrasonic wave, it is possible to detect a low object with high accuracy, or to determine the arrival direction of the ultrasonic wave with high accuracy when multipath (multiple propagation paths) occurs and suppress the influence.

[0097] In addition, specifically, it is possible to refer to the directivity corresponding information 230 ( Figure 8 )Change the directivity of the ultrasonic wave in the height direction.

[0098] In addition, the directivity of the ultrasonic wave in the height direction can be controlled, so if, for example, you want to determine whether the reflected wave is a reflection wave from the road surface or a reflection wave from an obstacle, you can obtain powerful information by controlling the directivity of the ultrasonic wave. If the reflected wave can be determined, the time for filtering irrelevant information (reflected waves from the road surface) can also be reduced in subsequent processing.

[0099] Next, Fig.10 is a flowchart showing the second process performed by the object detection system of the embodiment. Steps S21 to S24 are Fig. 9 Steps S11 to S14 are the same.

[0100] After step S24, in step S25, the processor 223 determines whether the distance has changed, and proceeds to step S26 if it is affirmative, and returns to step S22 if it is negative.

[0101] In step S26 , the processor 223 changes the directivity in the height direction of the ultrasonic wave transmitted by the transmission unit based on the directivity change information in which the degree of change in the height direction of the directivity is set according to the distance.

[0102] Thus, for example, when a low object on the ground is detected and the distance to the object gradually shortens, the directivity of the ultrasonic wave is gradually changed downward, so that the intensity of the reflected wave from the object can be maintained, thereby maintaining the accuracy of object detection.

[0103] Next, Fig.11 1 is a flowchart showing the third process performed by the object detection system of the embodiment. This series of processes is a process for calculating the height of the object reflecting the ultrasonic wave by obtaining the change information of the intensity of the reflected wave while changing the directivity of the ultrasonic wave in the height direction. Steps S31 to S34 are Fig. 9 Steps S11 to S14 are the same.

[0104] After step S34, in step S35, the processor 223 determines whether a prescribed condition is satisfied, and in the affirmative case, proceeds to step S37, and in the negative case, proceeds to step S36. The prescribed condition is a condition for determining whether sufficient information on changes in the intensity of the reflected wave is obtained, for example, obtaining a reflected wave with a stronger intensity for a first prescribed number of times or more, and / or obtaining a reflected wave with a weaker intensity for a second prescribed number of times or more, but is not limited thereto.

[0105] In step S36, processor 223 changes the directivity in the height direction based on a predetermined algorithm, and then returns to step S32.

[0106] In step S37 , the processor 223 calculates the height of the object reflecting the ultrasonic wave based on the change information of the intensity of the reflected wave.

[0107] In this way, for example, when the height of an object is unknown when it is detected, the height of the object can be calculated by changing the directivity of the height direction of the generated ultrasonic wave and recognizing the change in the intensity of the reflected wave.

[0108] The embodiments of the present disclosure are described above, but the embodiments described above are merely examples and are not intended to limit the scope of the invention. The embodiments described above can be implemented in various forms, and various omissions, substitutions, and changes can be made without departing from the gist of the invention. The embodiments described above are included in the scope and gist of the invention, and are included in the scope equivalent to the invention described in the claims.

[0109] For example, regarding the front electrode 4, in the above-mentioned embodiment, the example in which the whole electrode and a single electrode are both rectangular and divided into two is described, but it is not limited to this. The whole electrode or a single electrode may also be a shape other than a rectangle (triangle, circle, etc.), and the number of divisions may be three or more.

[0110] In addition, the rear electrode 7 may be divided into two or more electrodes.

[0111] Furthermore, the directional correspondence information 230 (correspondence relationship information) may be stored in a storage device external to the object detection device 200 .

[0112] In addition, two or more directional ultrasonic waves may be generated simultaneously from the transducer 211. In this case, the control unit 220 controls the generation of two or more directional ultrasonic waves by making at least one of the frequency and phase different, and then, when the ultrasonic wave is detected by the transceiver 210, it is determined which of the two or more directional ultrasonic waves the ultrasonic wave is a reflected wave based on the different frequencies and phases of the detected ultrasonic wave. In this way, by simultaneously transmitting ultrasonic waves with two or more directivities and determining the original ultrasonic wave when receiving, it is possible to suppress a sharp drop in signal strength due to multipath caused by obstacles with multiple reflection points, for example.

[0113] [Summary of this embodiment]

[0114] This embodiment has at least the following configurations.

[0115] The ultrasonic generating device comprises: a vibrator 211, which comprises a piezoelectric body 6 which generates ultrasonic waves by vibrating due to the piezoelectric effect when an alternating voltage is applied, and two or more electrodes (front electrodes 4a, 4b) arranged at positions with different heights on the surface of the piezoelectric body 6 and an opposing electrode (rear electrode 7) arranged at a position opposite to the two or more electrodes; and a control unit 220, which, upon receiving an ultrasonic generation instruction including information on the directivity of the generated ultrasonic wave, performs the following control: selects a combination of a voltage applying electrode and a ground electrode corresponding to the directivity in the ultrasonic generation instruction from the two or more electrodes and the opposing electrode, and applies an alternating voltage to the voltage applying electrode to generate ultrasonic waves, the voltage applying electrode being an electrode to which the alternating voltage is applied, and the ground electrode being an electrode set to a ground potential.

[0116] With such a configuration, the directivity of the ultrasonic wave in the height direction can be changed by a single transducer 211, so the cost is low.

[0117] In addition, the ultrasonic wave generating device further includes a storage unit (storage device 222) for storing information on the correspondence between the combination of the voltage applying electrode and the ground electrode in the two or more electrodes and the opposing electrodes and the directivity of the generated ultrasonic wave (directivity correspondence information 230). The control unit 220 controls the generation of the ultrasonic wave with reference to the correspondence information. Such a configuration is appropriate.

[0118] With such a configuration, the directivity of the ultrasonic wave in the height direction can be changed by referring to the above-mentioned correspondence information.

[0119] In addition, a vibrator 211 as an example of the present disclosure includes a piezoelectric body 6 that vibrates due to the piezoelectric effect when an AC voltage is applied to generate ultrasonic waves, and two or more electrodes arranged at different heights on the surface of the piezoelectric body 6 and an opposing electrode arranged at a position opposite to the two or more electrodes, wherein, among the above-mentioned two or more electrodes and the above-mentioned opposing electrode, the directivity of the ultrasonic waves generated is different depending on the selected combination of the voltage applying electrode and the ground electrode, the above-mentioned voltage applying electrode is an electrode to which an AC voltage is applied, and the above-mentioned ground electrode is an electrode set to a ground potential.

[0120] With such a configuration, the directivity of the ultrasonic wave in the height direction can be changed by a single transducer 211, so the cost is low.

[0121] In addition, the object detection device 200 as an example of the present disclosure includes a transmitting unit that transmits ultrasonic waves through a vibrator 211, a receiving unit that receives reflected waves of ultrasonic waves through the vibrator 211, and a control unit 220. The vibrator 211 includes a piezoelectric body 6 that generates ultrasonic waves by vibrating due to the piezoelectric effect when an AC voltage is applied, and two or more electrodes provided at positions with different heights on the surface of the piezoelectric body 6, and an opposing electrode provided at a position opposite to the two or more electrodes. When the control unit 220 receives an ultrasonic wave generation instruction including information on the directivity of the generated ultrasonic wave, the control unit 220 selects a combination of a voltage application electrode and a ground electrode corresponding to the directivity in the ultrasonic wave generation instruction from the two or more electrodes and the opposing electrode, and applies an AC voltage to the voltage application electrode to generate ultrasonic waves, wherein the voltage application electrode is an electrode to which the AC voltage is applied, and the ground electrode is an electrode set to a ground potential.

[0122] With such a configuration, the directivity of the ultrasonic wave in the height direction can be changed by a single transducer 211, so the cost is low.

[0123] In addition, the object detection device 200 further includes a storage unit (storage device 222) that stores information on the correspondence between the combination of the voltage applying electrode and the ground electrode in the two or more electrodes and the opposing electrodes and the directivity of the generated ultrasonic wave. The control unit 220 controls the generation of the ultrasonic wave with reference to the correspondence information. Such a configuration is appropriate.

[0124] With such a configuration, the directivity of the ultrasonic wave in the height direction can be changed by referring to the above-mentioned correspondence information.

[0125] In the object detection device 200, the control unit 220 calculates the distance to the object reflecting the ultrasonic wave based on the timing of the ultrasonic wave being transmitted by the transmitting unit and the timing of the reflected wave of the ultrasonic wave being received by the receiving unit, and when the distance changes with the passage of time, the control unit 220 changes the directivity in the height direction of the ultrasonic wave transmitted by the transmitting unit based on the directivity change information for setting the degree of change in the height direction of the directivity according to the distance. Such a configuration is suitable.

[0126] With such a configuration, when the distance changes with the passage of time, the directivity of the ultrasonic wave in the height direction is changed according to the distance, thereby maintaining the intensity of the reflected wave from the object, for example, and maintaining the accuracy of object detection.

[0127] In the above-mentioned object detection device 200, the control unit 220 changes the directivity of the ultrasonic wave transmitted by the transmission unit in the height direction, acquires change information of the intensity of the reflected wave, and calculates the height of the object reflecting the ultrasonic wave based on the change information.

[0128] With such a configuration, the height of the object reflecting the ultrasonic wave can be calculated by changing the directivity of the generated ultrasonic wave in the height direction and recognizing the change in the intensity of the reflected wave.

[0129] Furthermore, the effects achieved by the dependent claims and embodiments of the claims are other additional effects that are different from the effects achieved by the independent claims of the claims.

[0130] Description of Reference Numerals

[0131] 1…vehicle, 4…front electrode, 5…wiring, 6…piezoelectric body, 7…rear electrode, 8…wiring, 100…ECU, 200…object detection device, 210…transmitter / receiver, 211…oscillator, 212…switching unit, 220…control unit, 221…input / output device, 222…storage device, 223…processor, 230…directivity corresponding information.

Claims

1. An ultrasonic generating device, wherein: have: A vibrator comprising a piezoelectric body that vibrates due to piezoelectric effect to generate ultrasonic waves when an AC voltage is applied, two or more electrodes provided at positions with different heights on the surface of the piezoelectric body, and an opposing electrode provided at a position opposing the two or more electrodes; A control unit, which, upon receiving an ultrasonic generation instruction including information on the directionality of the generated ultrasonic wave, performs the following control: selects a combination of a voltage applying electrode and a ground electrode corresponding to the directionality in the ultrasonic generation instruction from the above-mentioned two or more electrodes and the above-mentioned opposing electrode, and applies an alternating current voltage to the above-mentioned voltage applying electrode to generate ultrasonic waves, wherein the above-mentioned voltage applying electrode is an electrode to which an alternating current voltage is applied, and the above-mentioned ground electrode is an electrode set to a ground potential.

2. The ultrasonic generating device according to claim 1, wherein: The apparatus further comprises a storage unit that stores information on a correspondence relationship between a combination of the voltage applying electrode and the ground electrode among the two or more electrodes and the counter electrode and the directivity of the generated ultrasonic wave, The control unit controls the generation of the ultrasonic wave with reference to the correspondence information.

3. A vibrator, wherein: have: a piezoelectric body that vibrates due to the piezoelectric effect to generate ultrasonic waves when an alternating voltage is applied thereto; and On the surface of the piezoelectric body, there are two or more electrodes arranged at positions with different heights and an opposing electrode arranged at a position opposite to the two or more electrodes, wherein, among the two or more electrodes and the opposing electrode, the directivity of the ultrasonic wave generated is different according to the selected combination of the voltage applying electrode and the grounding electrode, the voltage applying electrode is an electrode to which an AC voltage is applied, and the grounding electrode is an electrode set to a ground potential.

4. An object detection device, wherein: The device comprises a transmitting unit for transmitting ultrasonic waves by means of a transducer, a receiving unit for receiving reflected waves of the ultrasonic waves by means of the transducer, and a control unit. The vibrator comprises: a piezoelectric body which vibrates due to the piezoelectric effect to generate ultrasonic waves when an AC voltage is applied; and two or more electrodes arranged at positions with different heights on the surface of the piezoelectric body and an opposing electrode arranged at a position opposite to the two or more electrodes. When the control unit receives an ultrasonic generation instruction including information on the directionality of the generated ultrasonic wave, it selects a combination of a voltage applying electrode and a ground electrode corresponding to the directionality in the ultrasonic generation instruction from the two or more electrodes and the opposing electrode, and applies an alternating current voltage to the voltage applying electrode to generate ultrasonic waves, wherein the voltage applying electrode is an electrode to which an alternating current voltage is applied, and the ground electrode is an electrode set to a ground potential.

5. The object detection device according to claim 4, wherein: The apparatus further comprises a storage unit that stores information on a correspondence relationship between a combination of the voltage applying electrode and the ground electrode among the two or more electrodes and the counter electrode and the directivity of the generated ultrasonic wave, The control unit controls the generation of the ultrasonic wave with reference to the correspondence information.

6. The object detection device according to claim 4, wherein: The control unit calculates the distance to the object reflecting the ultrasonic wave based on the timing of the ultrasonic wave being sent by the transmitting unit and the timing of the reflected wave of the ultrasonic wave being received by the receiving unit, and when the distance changes with the passage of time, the control unit changes the directivity in the height direction of the ultrasonic wave sent by the transmitting unit based on directivity change information, wherein the directivity change information is information for setting the degree of change of the directivity in the height direction according to the distance.

7. The object detection device according to claim 4, wherein: The control unit changes the directivity in the height direction of the ultrasonic wave transmitted by the transmission unit, acquires change information of the intensity of the reflected wave, and calculates the height of the object reflecting the ultrasonic wave based on the change information.

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