Object detection device

Abstract

The present invention provides an object detection device. The object detection device (1) comprises: a signal generating unit (4), a driving unit (2), an object determining unit (8), and a driving control unit (3). The signal generating unit generates a pulse signal in a manner including a code for identifying ultrasonic waves. The driving unit drives the transceiver unit with a current or a voltage according to the pulse signal generated by the signal generating unit. The object determining unit compares the code included in the received wave with the code included in the pulse signal to determine whether the received wave is a reflected wave of the ultrasonic wave sent from the transceiver unit, and further determines whether the object exists within the detection range based on the amplitude of the received wave. When a predetermined amplitude rise time has passed, the driving control unit reduces the current or voltage input from the driving unit to the transceiver unit.

Description

[0001] Cross-reference to related applications: This application is based on Japanese Patent Application No. 2018-92155 filed on May 11, 2018, and the contents thereof are incorporated herein by reference. Technical Field

[0002] The present disclosure relates to an object detection device. Background Art

[0003] There is known a vehicle-mounted object detection device that detects obstacles by transmitting and receiving ultrasonic waves. For this object detection device, a technology is proposed that changes the frequency of the detection wave over time and compares the received wave with the frequency of the detection wave to avoid crosstalk with ultrasonic waves transmitted by other vehicles traveling nearby (for example, refer to Patent Document 1).

[0004] Patent Document 1: European Patent No. 2373434

[0005] In such a technology, in order to avoid interference caused by multiple reflections and improve the recognition accuracy of the received waves, it is preferable to shorten the transmission time of the detection waves.

[0006] However, if the transmission time of the detection wave is shortened when a resonant microphone is used as a transceiver for transmitting and receiving ultrasonic waves, it is difficult to observe the change in frequency after the reflected wave is just received. This is because: since the resonance microphone has a low ability to follow the input signal, it takes time from the start of the detection wave transmission to the increase in the amplitude of the detection wave. In addition, when the amplitude of the detection wave is small, it is difficult for the frequency characteristics of the input signal to appear in the detection wave.

[0007] This also applies to the case where the phase of the detection wave is changed instead of the frequency. When the amplitude of the detection wave is small, the phase characteristics of the input signal are less likely to appear in the detection wave. Summary of the invention

[0008] The present disclosure has been made in view of the above-mentioned points, and provides, for example, an object detection device capable of improving the followability of a detection wave with respect to an input signal input to a transmission and reception unit.

[0009] According to one aspect of the present disclosure, an object detection device comprises:

[0010] A transceiver unit, for transmitting and receiving detection waves, wherein the detection waves are ultrasonic waves;

[0011] A signal generating unit that generates a pulse signal in a manner including a code for identifying a detection wave;

[0012] a driving unit that drives the transceiver unit with current or voltage according to the pulse signal generated by the signal generating unit;

[0013] an object determination unit that compares the code included in the received wave with the code included in the pulse signal to determine whether the received wave is a reflected wave of the ultrasonic wave sent from the transceiver unit, and further determines whether the object is present in the detection range based on the amplitude of the received wave; and

[0014] The drive control unit reduces the current or voltage input from the drive unit to the transmission and reception unit when a predetermined amplitude rise time has elapsed.

[0015] As a result, since the current or voltage input to the transmission and reception unit increases during the amplitude rise time, the followability of the detection wave with respect to the pulse signal can be improved.

[0016] In addition, the reference numerals in parentheses attached to the components and the like are merely examples of the correspondence between the components and the specific configurations and the like described in the embodiments described later. Therefore, the present disclosure is not limited in any way by the description of such reference numerals. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a diagram showing the structure of the object detection device according to the first embodiment.

[0018] Figure 2 It is a diagram showing the frequency of a pulse signal, a driving current, and the amplitude and frequency of a received wave in a comparative example of the first embodiment.

[0019] Figure 3 is a flowchart of a process performed by the object detection device.

[0020] Figure 4 It is a diagram showing the frequency of the pulse signal, the drive current, and the amplitude and frequency of the received wave in the first embodiment.

[0021] Figure 5 It is a diagram showing the frequency of the pulse signal and the driving current in the second embodiment.

[0022] Figure 6 It is a diagram showing a pulse signal and a driving current in the third embodiment.

[0023] Figure 7 It is a diagram showing the amplitude and phase of a received wave in a comparative example of the third embodiment.

[0024] Figure 8 It is a diagram showing the amplitude and phase of the received wave in the third embodiment.

[0025] Fig. 9 It is a diagram showing the frequency of the pulse signal and the driving current in another embodiment.

[0026] Fig.10It is a diagram showing the frequency of the pulse signal and the driving current in another embodiment. DETAILED DESCRIPTION

[0027] Hereinafter, embodiments of the present disclosure will be described based on the drawings. In the following embodiments, the same or equivalent parts are denoted by the same codes for description.

[0028] (First Embodiment)

[0029] A first embodiment will be described. The object detection device of this embodiment is an ultrasonic sonar device, and the object detection device is mounted on a vehicle to detect an object outside the vehicle.

[0030] like Figure 1 As shown, the object detection device includes a microphone 1 , a driving unit 2 , a driving control unit 3 , a signal generating unit 4 , a control unit 5 , a storage unit 6 , a receiving circuit 7 , and an object determining unit 8 .

[0031] The control unit 5, object determination unit 8, etc. are constituted by a well-known microcomputer having a CPU, ROM, RAM, I / O, etc. The control unit 5 and object determination unit 8 execute various calculations and other processing according to the program stored in the ROM, etc. The ROM and RAM are non-transitory physical storage media.

[0032] Microphone 1 transmits and receives ultrasonic waves and outputs a signal corresponding to the received wave, which is equivalent to a transceiver. Microphone 1 is arranged to face the outer surface of the vehicle, and transmits a detection wave for detecting an object toward the outside of the vehicle. Specifically, microphone 1 has a piezoelectric element not shown in the figure, and the piezoelectric element is a structure in which a piezoelectric layer is arranged between two electrodes facing each other. The two electrodes are connected to a driving unit 2. An alternating current or an alternating voltage is supplied from the driving unit 2 to the two electrodes to deform the piezoelectric layer, thereby transmitting a detection wave from microphone 1 to the outside of the vehicle, and the detection wave is an ultrasonic wave.

[0033] The driving unit 2 applies a driving current or a driving voltage to the microphone 1 according to the pulse signal input from the driving control unit 3. The pulse signal input to the driving unit 2 is generated by the signal generating unit 4. In the present embodiment, the driving control unit 3 is arranged between the driving unit 2 and the signal generating unit 4, and the pulse signal generated by the signal generating unit 4 is input to the driving unit 2 via the driving control unit 3.

[0034] The drive control unit 3 controls the drive current or drive voltage applied to the microphone 1. In order to make the drive current or drive voltage applied to the microphone 1 a desired value, the drive control unit 3 adjusts the amplitude of the pulse signal generated by the signal generation unit 4 and inputs the adjusted pulse signal to the drive unit 2. When the prescribed amplitude rise time has passed, the drive control unit 3 reduces the current or voltage input from the drive unit 2 to the microphone 1.

[0035] In addition, the signal generating unit 4 generates a pulse signal in a manner including a code for identifying ultrasonic waves according to the transmission instruction from the control unit 5. The code is used to identify the reflected wave of the detection wave transmitted by the microphone 1, the ultrasonic wave transmitted from other object detection devices, etc. By using the code to identify the received wave, it is possible to avoid crosstalk with ultrasonic waves transmitted from other devices, realize simultaneous measurement using multiple microphones, and improve the reliability of measurement and shorten the measurement cycle.

[0036] In this embodiment, the identification code is represented by a frequency pattern, and the signal generator 4 generates a pulse signal including a chirp signal whose frequency changes in a predetermined pattern over time. As a result, an ultrasonic wave including the chirp signal is transmitted as a detection wave from the microphone 1. In addition, the amplitude of the pulse signal generated by the signal generator 4 is set to be constant.

[0037] As the chirp signal, an uplink chirp signal indicating code “0” and a downlink chirp signal indicating code “1” are used. The uplink chirp signal is a signal whose frequency increases with the passage of time, and the downlink chirp signal is a signal whose frequency decreases with the passage of time.

[0038] For example, when the 2-bit code "01" is used as the identification code, the pulse signal is generated in the order of the uplink chirp signal and the downlink chirp signal. Also, when the code "10" is used as the identification code, the pulse signal is generated in the order of the downlink chirp signal and the uplink chirp signal.

[0039] The drive control unit 3 changes the current or voltage input by the drive unit 2 to the microphone 1 according to each code. The drive current and drive voltage suitable for increasing the amplitude of the detection wave are different according to the individual differences of the microphones, and are different in the uplink chirp signal and the downlink chirp signal. The drive current or drive voltage for each uplink chirp signal and the downlink chirp signal is set in consideration of the individual differences of the microphone 1, and is stored in the storage unit 6. The storage unit 6 is a non-transitional physical storage medium. For example, when manufacturing an object detection device, the sound pressure of the detection wave is measured at a position at a predetermined distance from the microphone 1, and the drive current is set in such a way that the sound pressure becomes a desired value.

[0040] The two electrodes of the piezoelectric element included in the microphone 1 are also connected to the receiving circuit 7 . When the microphone 1 receives ultrasonic waves, the piezoelectric layer deforms to generate a voltage between the two electrodes, and the voltage is input to the receiving circuit 7 .

[0041] The receiving circuit 7 performs processing such as A / D conversion, amplification, and filtering on the output signal of the microphone 1 , and the signal generated by the receiving circuit 7 is output to the object determination unit 8 .

[0042] The object determination unit 8 compares the code included in the received wave with the code included in the pulse signal to determine whether the received wave is a reflected wave of the detection wave transmitted from the microphone 1 and whether an object exists in the detection range based on the amplitude of the received wave.

[0043] Specifically, the object determination unit 8 mixes the output signal of the receiving circuit 7 with the pulse signal generated by the signal generating unit 4, and extracts information such as the frequency and amplitude of the received wave from the output signal of the receiving circuit 7. Then, the object determination unit 8 generates a frequency waveform and an amplitude waveform based on the extracted information, identifies the received wave based on the frequency waveform detection code, and calculates the propagation time of the ultrasonic wave based on the amplitude waveform to detect the object.

[0044] For example, when the signal generator 4 generates a pulse signal including code “0”, the object determiner 8 determines that the received wave is a reflected wave of the probe wave transmitted from the microphone 1 when detecting an uplink chirp signal indicating code “0” from the frequency waveform of the received wave.

[0045] The object determination unit 8 detects the code by, for example, comparing the frequency waveform of the received wave with a specified reference waveform. In addition, since the microphone 1 has a low ability to follow the input signal, a frequency difference occurs between the pulse signal generated by the signal generation unit 4 and the signal output by the microphone 1 when the reflected wave of the detection wave is received. Specifically, when the microphone 1 receives the reflected wave of the detection wave, the frequency of the output signal of the microphone 1 changes over time in the opposite direction to the pulse signal, or changes more slowly than the pulse signal, and then changes in the same way as the pulse signal. Therefore, the reference waveform used by the object determination unit 8 to detect the code changes as described above. In the later described Figure 2 , Figure 4 In the following, a case is described in which the frequency of the output signal of the microphone 1 changes in a V shape when the reflected wave of the detection wave is received.

[0046] If the object determination unit 8 determines that the received wave is a reflected wave of the detection wave, the amplitude of the received wave is compared with a predetermined threshold value, and the distance to the object that reflected the detection wave is calculated based on the time from the microphone 1 sending the detection wave until the amplitude of the received wave becomes greater than the threshold value. Then, the object determination unit 8 determines whether the object is within the detection range based on the calculated distance. The determination result of the object determination unit 8 is sent to the control unit 5, and the control unit 5 reports to the driver based on the determination result of the object determination unit 8.

[0047] The operation of the object detection device is described. If a resonant microphone 1 having a piezoelectric element is used as the transceiver, it takes time for the amplitude of the detection wave to increase from the start of the transmission of the detection wave because the microphone 1 has a low ability to follow the input signal from the driver 2. In addition, if the amplitude of the detection wave is small, the frequency characteristics of the input signal are unlikely to appear in the detection wave. Therefore, for example, Figure 2 As shown in FIG. 1 , if a driving current or driving voltage with a constant amplitude is input to the microphone 1 to transmit a detection wave, it is difficult to observe the change in the frequency of the received wave after the reception of the reflected wave begins. Figure 2 The portion surrounded by the dashed line in the frequency waveform of the received wave corresponds to the portion where the frequency sweep starts in the pulse signal including the uplink chirp signal, but the frequency of the portion surrounded by the dashed line is larger than the design lower limit of the frequency sweep. Therefore, the frequency change of the received wave becomes smaller, and the detection of the code becomes difficult.

[0048] Therefore, in this embodiment, the amplitude of the driving current or driving voltage of the microphone 1 is increased before the amplitude of the detection wave rises, so that the frequency change also occurs after the reflected wave is just received. Figure 3 The process shown is used to send the detection wave.

[0049] In step S1, the signal generation unit 4 generates a pulse signal including a code for ultrasonic identification. The object detection device proceeds from step S1 to step S2, where the drive control unit 3 determines whether a predetermined amplitude rise time has elapsed.

[0050] The amplitude rise time is set to include at least a portion of the time from the state where the amplitude of the detection wave is less than a specified value to the state where the amplitude of the detection wave is greater than a specified value and the rise of the amplitude ends. Specifically, the amplitude rise time is set to, for example, a specified time from the start of generating a pulse signal. In addition, for example, when using a code of more than 2 bits, the amplitude rise time is set to a specified time from the start of generating a pulse signal representing 1 code, and the drive current after the code conversion is larger than that before the code conversion.

[0051] If the drive control unit 3 determines that the amplitude rise time has not elapsed, the object detection device proceeds to step S3 . If the drive control unit 3 determines that the amplitude rise time has elapsed, the object detection device proceeds to step S4 .

[0052] In step S3, the drive control unit 3 inputs a drive current or a drive voltage greater than a predetermined value to the microphone 1. As a result, the amplitude of the detection wave transmitted from the microphone 1 increases compared to when a drive current or a drive voltage below a predetermined value is input to the microphone 1. In step S4, the drive control unit 3 inputs a drive current or a drive voltage below a predetermined value to the microphone 1. In this way, when the amplitude rise time has passed, the drive control unit 3 reduces the current or voltage input from the drive unit 2 to the microphone 1.

[0053] The object detection device proceeds from step S3 and step S4 to step S5, in which the control unit 5 determines whether a detection wave corresponding to the specified number of pulses has been sent. If the control unit 5 determines that a detection wave corresponding to the specified number of pulses has been sent, the object detection device ends the detection wave sending process, and if the control unit 5 determines that a detection wave corresponding to the specified number of pulses has not been sent, the object detection device proceeds to step S1.

[0054] pass Figure 3 In the present embodiment, as shown in the process Figure 4 As shown in FIG. 1 , the driving current or driving voltage of the microphone 1 increases from the start of the pulse signal generation to the lapse of the predetermined time compared to after the lapse of the predetermined time. As a result, the detection wave is more capable of following the pulse signal during the amplitude rise time, and the change in the frequency of the received wave is more easily observed. Figure 4 The part surrounded by the dotted line is Figure 2 In contrast, the frequency of the received wave approaches the design lower limit value of the frequency sweep, and thus, the frequency variation of the received wave increases.

[0055] Furthermore, if a large driving current or driving voltage is always applied to the microphone 1, the characteristics of the frequency of the received wave can be easily observed, but the transmitted sound pressure will be excessively increased. In addition, a capacitor that is charged to drive the microphone 1 is configured in the drive control unit 3. In the case of transmitting a detection wave containing a long code sequence, if a large driving current is always applied to the microphone 1, the charge charged to the capacitor will disappear. Therefore, in this embodiment, the driving current applied to the microphone 1 is increased only during the amplitude rise time, and the driving current is reduced after the amplitude rise time has passed.

[0056] (Second Embodiment)

[0057] The second embodiment is described. This embodiment is obtained by changing the frequency of the pulse signal in the first embodiment. Since the other structures are the same as those in the first embodiment, only the parts different from the first embodiment will be described.

[0058] like Figure 5As shown, in this embodiment, the signal generating unit 4 changes the frequency of the pulse signal after generating a pulse signal with a predetermined number of pulses and a constant frequency. The frequency at the time of starting to generate the pulse signal is a frequency near the resonance frequency of the microphone 1. The drive control unit 3 makes the drive current, etc. during the period when the frequency of the pulse signal is constant greater than a predetermined value, and makes the drive current, etc. after starting the frequency sweep be less than a predetermined value.

[0059] In this way, by sweeping the frequency of the pulse signal after driving the microphone 1 at a frequency near the resonance frequency, the amplitude at the start of the sweep increases, and the frequency change of the pulse signal is easy to appear in the received wave. In addition, by making the drive current before the frequency sweep larger than a specified value, the frequency change appearing in the received wave is further increased.

[0060] In addition, in this embodiment, the code is represented by the portion of the pulse signal that sweeps the frequency. When two or more such pulse signals are continuous and a probe wave containing a code of two or more bits is transmitted, the amplitude rise time is, for example, a predetermined time from the end of the first pulse signal.

[0061] (Third Embodiment)

[0062] The third embodiment is described below. This embodiment is obtained by changing the method of expressing codes compared to the first embodiment. Since the other structures are the same as the first embodiment, only the parts different from the first embodiment will be described below.

[0063] In this embodiment, the frequency of the pulse signal is constant, and the code for ultrasonic identification is expressed by the phase. Specifically, a signal with a phase of 0° expresses a code "0", and a signal with a phase of 180° expresses a code "1".

[0064] For example, when using the 2-digit code "01" as the identification code, Figure 6 As shown, after generating a pulse signal with a phase of 0° of a predetermined number of pulses, a pulse signal with a phase of 180° of a predetermined number of pulses is generated. In this embodiment, the amplitude rise time is set to a predetermined time from when the phase of the pulse signal changes discontinuously in this way, and the drive control unit 3 makes the drive current greater than a predetermined value during the amplitude rise time. Moreover, the drive current is set to be less than the predetermined value from the start of generating the start pulse signal to before the code is converted and after the amplitude rise time has passed.

[0065] The object determination unit 8 extracts phase information from the output of the receiving circuit 7 and compares the code detected from the phase of the received wave with the code included in the pulse signal. If the codes match, the object determination unit 8 determines that the received wave is a reflected wave of the detection wave sent from the microphone 1.

[0066] When the code is expressed by the phase in this way, the phase of the pulse signal may change discontinuously when the bit is switched. In this case, since the tracking performance of the microphone 1 is low, the amplitude of the detection wave after the phase switching is smaller than that before the phase switching.

[0067] On the other hand, by making the driving current of the microphone 1 larger than a predetermined value during the amplitude rise time, the amplitude of the received wave after code conversion increases, and the detection of the phase of the received wave becomes easier.

[0068] For example, when the 8-bit code "00010111" is used as the identification code, if the drive current and the like are always set to be below a predetermined value, Figure 7 As shown in FIG. 1 , the amplitude of the received wave decreases after the bit conversion. That is, as shown in the portion surrounded by the dashed line, after the code included in the received wave is converted from the third bit code "0" to the fourth bit code "1", the amplitude of the received wave decreases. Therefore, it becomes difficult to detect the fourth bit code "1".

[0069] In contrast, by making the drive current greater than a specified value within a specified time after the code included in the detection wave is converted from the third bit code "0" to the fourth bit code "1", Figure 8 As shown, the amplitude of the received wave increases. As a result, it is easy to detect the fourth code "1". In addition, Figure 7 , Figure 8 The dotted line in the phase graph represents the phase of the pulse signal.

[0070] exist Figure 8 2 shows a case where the driving current is increased for the fourth code, but similarly, for the fifth and sixth codes, the detection of the code is also facilitated by increasing the driving current after the code conversion.

[0071] (Other Embodiments)

[0072] In addition, the present disclosure is not limited to the above-mentioned embodiment, and can be modified appropriately.

[0073] For example, in the above second embodiment, if Fig. 9 As shown in FIG. 1 , the drive current can be slowly reduced after the amplitude rise time has passed. Fig.10 As shown in FIG. 1 , the drive current may be gradually reduced after the amplitude rise time has passed and then increased. The resonance type microphone 1 has a characteristic that the peak amplitude is obtained at the resonance frequency and the amplitude decreases as the amplitude moves away from the resonance frequency. Fig.10In the example shown, by sweeping the frequency of the pulse signal around the resonance frequency of the microphone 1 and changing the drive current etc. as described above, the characteristics of the microphone 1 can be corrected to reduce the change in the amplitude of the detection wave. Fig. 9 , Fig.10 As shown, the driving current etc. are changed.

[0074] Furthermore, drive control unit 3 may control the current or voltage input from drive unit 2 to microphone 1 in a manner to correct changes in the characteristics of microphone 1. When the performance of the object detection device is degraded, the robustness to environmental changes can be improved by increasing the drive current.

[0075] For example, the driving current or driving voltage may be controlled according to the temperature characteristics of the microphone 1. In addition, the driving current or driving voltage may be controlled according to the distance to the detection object, taking into account the attenuation of the reflected wave caused by the distance to the object. For example, the longer the distance to the detection object, the greater the driving current. In addition, the driving current or driving voltage may be controlled according to the ambient temperature. For example, since the higher the ambient temperature, the greater the distance attenuation of the reflected wave, and the lower the ambient temperature, the smaller the distance attenuation, the higher the ambient temperature, the greater the driving current. In addition, the driving current or driving voltage may be controlled according to the relative speed of the object relative to the microphone 1. Since the greater the relative speed of the object, the greater the displacement of the frequency of the reflected wave relative to the detection wave, the driving current may be increased in proportion to the relative speed, for example, so that the change in frequency may be easily detected.

[0076] In addition, if a code of more than 2 bits is used in the above-mentioned first embodiment and the second embodiment to generate a pulse signal continuously containing the same code, the frequency of the pulse signal changes discontinuously during the bit conversion. In this case, the amplitude rise time can also be set to a specified time from the discontinuous change of the frequency of the pulse signal. In addition, in the case where the frequency of the pulse signal changes discontinuously like this, and in the case where the phase of the pulse signal changes discontinuously as in the above-mentioned third embodiment, it is also possible to increase the drive current only when the pulse signal is started to be generated, and not change the drive current, etc. during the bit conversion.

[0077] Furthermore, a microphone 1 for transmitting ultrasonic waves and a microphone 1 for receiving ultrasonic waves may be provided, and a transceiver may be constituted by two microphones 1. Furthermore, the present disclosure may be applied to an object detection device mounted on equipment other than a vehicle.

Claims

1. An object detection device, comprising: A transceiver unit, for transmitting and receiving detection waves, wherein the detection waves are ultrasonic waves; A signal generating unit that generates a pulse signal in a manner including a code for identifying a detection wave; A driving unit, which drives the transceiver unit with current or voltage according to the pulse signal generated by the signal generating unit; The object determination unit compares the code included in the received wave with the code included in the pulse signal to determine whether the received wave is a reflected wave of the ultrasonic wave sent from the above-mentioned transceiver unit, and further determines whether the object is present in the detection range based on the amplitude of the received wave; as well as The drive control unit increases the current or voltage input from the drive unit to the transceiver unit during the specified amplitude rise time compared to after the amplitude rise time has passed, so that the change in the frequency of the received wave based on the code also occurs after the reflected wave is just received, and then reduces the current or voltage input from the drive unit to the transceiver unit after the amplitude rise time has passed. The object determination unit mixes the output signal of the receiving circuit with the pulse signal, and extracts the frequency and amplitude of the received wave from the output signal of the receiving circuit, generates a frequency waveform and an amplitude waveform according to the extracted frequency and amplitude, identifies the received wave according to the frequency waveform detection code, and calculates the propagation time of the ultrasonic wave according to the amplitude waveform to detect the object.

2. The object detection device according to claim 1, wherein: The signal generating unit generates a pulse signal having a predetermined number of pulses and a constant frequency, and then changes the frequency of the pulse signal.

3. The object detection device according to claim 1, wherein: The signal generating unit generates a pulse signal in such a manner that two codes are represented by an uplink chirp signal and a downlink chirp signal, wherein the frequency of the uplink chirp signal increases with the passage of time, and the frequency of the downlink chirp signal decreases with the passage of time, The drive control unit changes a current or a voltage input from the drive unit to the transceiver unit for each code.

4. The object detection device according to any one of claims 1 to 3, wherein: The drive control unit controls a current or a voltage input from the drive unit to the transceiver unit in such a manner as to correct a characteristic change of the transceiver unit.

5. The object detection device according to claim 4, wherein: The drive control unit controls a current or a voltage input from the drive unit to the transceiver unit according to a temperature characteristic of the transceiver unit.

6. The object detection device according to claim 4, wherein: The drive control unit controls the current or voltage input from the drive unit to the transceiver unit according to the distance of the detection object.

7. The object detection device according to claim 4, wherein: The drive control unit controls the current or voltage input from the drive unit to the transceiver unit according to the ambient temperature.

8. The object detection device according to claim 4, wherein: The drive control unit controls a current or a voltage input from the drive unit to the transceiver unit according to a relative speed of the object with respect to the transceiver unit.

9. An object detection device comprising: A transceiver unit, for transmitting and receiving detection waves, wherein the detection waves are ultrasonic waves; A signal generating unit that generates a pulse signal in a manner including a code for identifying a detection wave; A driving unit, which drives the transceiver unit with current or voltage according to the pulse signal generated by the signal generating unit; The object determination unit compares the code included in the received wave with the code included in the pulse signal to determine whether the received wave is a reflected wave of the ultrasonic wave sent from the above-mentioned transceiver unit, and further determines whether the object is present in the detection range based on the amplitude of the received wave; as well as The drive control unit reduces the current or voltage input from the drive unit to the transceiver unit when a predetermined amplitude rise time has passed. The signal generating unit generates a pulse signal in a manner that represents a code by changing the frequency. The signal generating unit changes the frequency of the pulse signal after generating a pulse signal with a predetermined number of pulses and a constant frequency. The object determination unit mixes the output signal of the receiving circuit with the pulse signal, and extracts the frequency and amplitude of the received wave from the output signal of the receiving circuit, generates a frequency waveform and an amplitude waveform according to the extracted frequency and amplitude, identifies the received wave according to the frequency waveform detection code, and calculates the propagation time of the ultrasonic wave according to the amplitude waveform to detect the object.

10. The object detection device according to claim 9, wherein: The above-mentioned amplitude rise time is: the specified time from the start of pulse signal generation, or the specified time from the discontinuous change in the frequency or phase of the pulse signal, or the specified time from the start of pulse signal generation representing 1 code, or the specified time from the end of the first pulse signal when two pulse signals representing the code are continuous.

11. The object detection device according to claim 9, wherein: The signal generating unit generates a pulse signal in such a manner that two codes are represented by an uplink chirp signal and a downlink chirp signal, wherein the frequency of the uplink chirp signal increases with the passage of time, and the frequency of the downlink chirp signal decreases with the passage of time, The drive control unit changes a current or a voltage input from the drive unit to the transceiver unit for each code.

12. The object detection device according to any one of claims 9 to 11, wherein: The drive control unit controls a current or a voltage input from the drive unit to the transceiver unit in such a manner as to correct a characteristic change of the transceiver unit.

13. The object detection device according to claim 12, wherein: The drive control unit controls a current or a voltage input from the drive unit to the transceiver unit according to a temperature characteristic of the transceiver unit.

14. The object detection device according to claim 12, wherein: The drive control unit controls the current or voltage input from the drive unit to the transceiver unit according to the distance of the detection object.

15. The object detection device according to claim 12, wherein: The drive control unit controls the current or voltage input from the drive unit to the transceiver unit according to the ambient temperature.

16. The object detection device according to claim 12, wherein: The drive control unit controls a current or a voltage input from the drive unit to the transceiver unit according to a relative speed of the object with respect to the transceiver unit.

17. An object detection device comprising: A transceiver unit, for transmitting and receiving detection waves, wherein the detection waves are ultrasonic waves; A signal generating unit that generates a pulse signal in a manner including a code for identifying a detection wave; A driving unit, which drives the transceiver unit with current or voltage according to the pulse signal generated by the signal generating unit; The object determination unit compares the code included in the received wave with the code included in the pulse signal to determine whether the received wave is a reflected wave of the ultrasonic wave sent from the above-mentioned transceiver unit, and further determines whether the object is present in the detection range based on the amplitude of the received wave; as well as The drive control unit reduces the current or voltage input from the drive unit to the transceiver unit when a predetermined amplitude rise time has passed. The signal generating unit generates a pulse signal in a manner that represents a code by changing the frequency. The signal generating unit generates a pulse signal in such a manner that two codes are represented by an uplink chirp signal and a downlink chirp signal, wherein the frequency of the uplink chirp signal increases with the passage of time, and the frequency of the downlink chirp signal decreases with the passage of time, The drive control unit changes the current or voltage input from the drive unit to the transceiver unit for each code. The object detection device further includes a storage unit for storing the current or voltage input from the drive unit to the transceiver unit, respectively, for two codes represented by the uplink chirp signal and the downlink chirp signal. The object determination unit mixes the output signal of the receiving circuit with the pulse signal, and extracts the frequency and amplitude of the received wave from the output signal of the receiving circuit, generates a frequency waveform and an amplitude waveform according to the extracted frequency and amplitude, identifies the received wave according to the frequency waveform detection code, and calculates the propagation time of the ultrasonic wave according to the amplitude waveform to detect the object.

18. The object detection device according to claim 17, wherein: The above-mentioned amplitude rise time is: the specified time from the start of pulse signal generation, or the specified time from the discontinuous change in the frequency or phase of the pulse signal, or the specified time from the start of pulse signal generation representing 1 code, or the specified time from the end of the first pulse signal when two pulse signals representing the code are continuous.

19. The object detection device according to claim 17, wherein: The signal generating unit generates a pulse signal in a manner including a plurality of continuous codes. The drive control unit makes the current or voltage input from the drive unit to the transceiver unit larger after the code conversion than the current or voltage before the code conversion.

20. The object detection device according to any one of claims 17 to 19, wherein: The drive control unit controls a current or a voltage input from the drive unit to the transceiver unit in such a manner as to correct a characteristic change of the transceiver unit.

21. The object detection device according to claim 20, wherein: The drive control unit controls a current or a voltage input from the drive unit to the transceiver unit according to a temperature characteristic of the transceiver unit.

22. The object detection device according to claim 20, wherein: The drive control unit controls the current or voltage input from the drive unit to the transceiver unit according to the distance of the detection object.

23. The object detection device according to claim 20, wherein: The drive control unit controls the current or voltage input from the drive unit to the transceiver unit according to the ambient temperature.

24. The object detection device according to claim 20, wherein: The drive control unit controls a current or a voltage input from the drive unit to the transceiver unit according to a relative speed of the object with respect to the transceiver unit.

25. An object detection device comprising: A transceiver unit, for transmitting and receiving detection waves, wherein the detection waves are ultrasonic waves; A signal generating unit that generates a pulse signal in a manner including a code for identifying a detection wave; A driving unit, which drives the transceiver unit with current or voltage according to the pulse signal generated by the signal generating unit; The object determination unit compares the code included in the received wave with the code included in the pulse signal to determine whether the received wave is a reflected wave of the ultrasonic wave sent from the above-mentioned transceiver unit, and further determines whether the object is present in the detection range based on the amplitude of the received wave; as well as The drive control unit reduces the current or voltage input from the drive unit to the transceiver unit when a predetermined amplitude rise time has passed. The signal generating unit generates a pulse signal in a manner including a plurality of continuous codes. The drive control unit makes the current or voltage input from the drive unit to the transceiver unit after the code conversion greater than the current or voltage before the code conversion. The object determination unit mixes the output signal of the receiving circuit with the pulse signal, and extracts the frequency and amplitude of the received wave from the output signal of the receiving circuit, generates a frequency waveform and an amplitude waveform according to the extracted frequency and amplitude, identifies the received wave according to the frequency waveform detection code, and calculates the propagation time of the ultrasonic wave according to the amplitude waveform to detect the object.

26. The object detection device according to claim 25, wherein: The above-mentioned amplitude rise time is: the specified time from the start of pulse signal generation, or the specified time from the discontinuous change in the frequency or phase of the pulse signal, or the specified time from the start of pulse signal generation representing 1 code, or the specified time from the end of the first pulse signal when two pulse signals representing the code are continuous.

27. The object detection device according to claim 25 or 26, wherein: The drive control unit controls a current or a voltage input from the drive unit to the transceiver unit in such a manner as to correct a characteristic change of the transceiver unit.

28. The object detection device according to claim 27, wherein: The drive control unit controls a current or a voltage input from the drive unit to the transceiver unit according to a temperature characteristic of the transceiver unit.

29. The object detection device according to claim 27, wherein: The drive control unit controls the current or voltage input from the drive unit to the transceiver unit according to the distance of the detection object.

30. The object detection device according to claim 27, wherein: The drive control unit controls the current or voltage input from the drive unit to the transceiver unit according to the ambient temperature.

31. The object detection device according to claim 27, wherein: The drive control unit controls a current or a voltage input from the drive unit to the transceiver unit according to a relative speed of the object with respect to the transceiver unit.

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