Ultrasonic transducer, method of operating an ultrasonic transducer, and method of measuring distance

Abstract

The present invention relates to an ultrasonic transducer, a method for operating an ultrasonic transducer, and a method for measuring distance. The ultrasonic transducer (1) comprises an excitation means (21), an attenuation means (22), a detection means (23), an adaptive means (24), and a membrane (4). The excitation means (21) is configured to excite the membrane (4) to emit ultrasonic waves (7). The attenuation means (22) is configured to attenuate the after-vibrations (40) of the membrane (4) that occur after excitation with an attenuation signal (5). The detection means (23) is configured to detect the amplitude of the after-vibrations (40) of the membrane (4). The adaptive means (24) is configured to determine the attenuation signal (5) depending on the detected amplitude of the after-vibrations (40).

Description

Technical Field

[0001] The present invention relates to an ultrasonic transducer, a method for operating an ultrasonic transducer, and a distance measurement method.

Background Art

[0002] Piezoelectric ultrasonic transducers are used for both transmitting and receiving ultrasonic signals, for example, as automotive distance sensors. However, such ultrasonic transducers conventionally continue to transmit ultrasonic waves even after all excitation for transmitting ultrasonic signals has ended. This is particularly due to the after-vibration of the membrane of the ultrasonic transducer used to generate the ultrasonic signal. This after-vibration, also referred to in English as "ringing," makes it difficult to detect ultrasonic signals with the same membrane.

[0003] Ultrasonic transducers and methods for operating ultrasonic transducers are described in publications US 4,580,251, US 6,731,569 B2, Liu et al. "Reducing ring-down time of pMUTs with phase shift of driving Waveform" Sensors and Actuators A 281(2018)100-107, and Wu et al. "A Novel Transfer Function Based Ring-Down SuppressionSystem for PMUTs" Sensors 2021,21,6414.

Summary of the Invention

[0004] The problem to be solved is to provide an improved ultrasonic transducer and an improved method for operating an ultrasonic transducer. These problems are achieved by an object having the features of independent claim 1 and a method having the features of claim 17.

[0005] An ultrasonic transducer is provided comprising excitation means, damping means, detection means, and adaptive means, as well as a membrane. The excitation means is configured to excite a membrane, diaphragm, or other membrane to emit ultrasonic waves (zum Aussenden). The damping means is configured to attenuate after-vibrations, residual vibrations, or rigging (Nachschwingung) of the membrane that occur after excitation with a damping signal. The detection means is configured to detect the amplitude of the after-vibrations of the membrane. The adaptive means is configured to determine the damping signal depending on the detected amplitude of the after-vibrations.

[0006] In particular, by detecting the amplitude of the after-vibrations, an adaptive means is used to determine the damping signal so that the after-vibrations of the membrane can be effectively dampened. Since the amplitude of the after-vibrations is explicitly measured, it is possible to dynamically respond to changes in environmental conditions and application requirements and advantageously select the damping of the after-vibrations of the membrane.

[0007] In the intended operation of an ultrasonic transducer, the excitation means can excite the membrane to emit an ultrasonic signal. In particular, after the excitation of the membrane is complete, the after-vibrations of the membrane can be attenuated by the damping means, and the damping signal is applied to the membrane, for example. In particular, after the damping signal is applied, the amplitude of the after-vibrations can be detected using a sensing element. In other words, the amplitude of the after-vibrations can be measured. For example, the after-vibrations of the membrane can be converted into a voltage by the piezoelectric effect, and the after-vibrations of the membrane can be derived from this voltage.

[0008] The adaptive element can determine the attenuation signal. For example, if the amplitude of the membrane's after-vibration is measured during operation before determining the attenuation signal, the attenuation signal can be advantageously determined so that the amplitude of the membrane's after-vibration is reduced or minimized. In other words, the ultrasonic transducer can determine the attenuation signal as optimally as possible based on detecting the amplitude of the membrane's after-vibration, thereby minimizing the membrane's after-vibration as much as possible. Therefore, the ultrasonic transducer can dynamically respond to changing environmental conditions, application requirements, measurement conditions, etc., and advantageously determine the attenuation accordingly. Thus, the ultrasonic transducer can be advantageously used to measure over a wide range of distances under multiple external conditions.

[0009] In particular, the excitation means, damping means, and detection means include a piezoelectric element. For example, the excitation means, damping means, and / or detection means are formed by a piezoelectric element. In particular, the excitation means, damping means, and detection means are formed by the same piezoelectric element. That is, the ultrasonic transducer is equipped with a piezoelectric element, which acts as an excitation means, a damping means, and a detection means, preferably performing the functions of an excitation means, a damping means, and a detection means. The piezoelectric element may also be a piezoelectric disk.

[0010] At least one of the excitation means, attenuation means, and detection means may include control electronic equipment. The control electronic equipment, for example, supplies a signal to the piezoelectric element in the case of the excitation and attenuation elements, and evaluates the signal from the piezoelectric element in the case of the detection means.

[0011] Piezoelectric elements can be connected to the control electronics of ultrasonic transducers. For example, the control electronics may include at least one of the following electronic components: a microcontroller, an application-specific integrated circuit (also known as an ASIC), or a field-programmable gate array (also known as an FPGA).

[0012] For example, a damping signal is supplied to the damping means by a control electronic device. For example, the damping means is electrically conductively connected to the control electronic device.

[0013] In particular, the excitation means is configured to excite the film with an excitation signal. The excitation signal is supplied, for example, from control electronic equipment. Preferably, the excitation signal substantially determines the ultrasonic signal emitted by the film and therefore the ultrasonic transducer. Thus, by determining the excitation signal, the shape, length, frequency, etc., of the ultrasonic signal can be determined.

[0014] The attenuated signal can be phase-shifted by 180° relative to the excitation signal. This phase shift of the attenuated signal allows for efficient attenuation.

[0015] The attenuation signal and the excitation signal can have the same amplitude. This allows the excitation and attenuation signals to be generated in substantially the same way and of substantially the same type, thus enabling particularly simple operation of the ultrasonic transducer.

[0016] The damping signal may include at least one damping pulse. The adaptive means is configured to determine at least one of the following parameters of the damping signal: the number of damping pulses, the width of at least one damping pulse, and the sequence of at least one damping pulse, in particular, depending on the amplitude of the detected afteroscillation.

[0017] For example, an attenuation signal can have one or more attenuation pulses. The width of at least one attenuation pulse is determined, in particular, based on the duration for which the attenuation signal has the attenuation pulse. For example, the attenuation pulse is a rectangular pulse. That is, the attenuation signal has a predetermined non-zero voltage for the duration for which the attenuation signal exhibits the attenuation pulse. The time span during which the attenuation signal has this voltage determines, in particular, the width of the attenuation pulse.

[0018] For example, if the attenuation signal has only one attenuation pulse, the sequence of that single attenuation pulse can represent the time between the completion of excitation of the film by the excitation means and the occurrence of the attenuation pulse. If the attenuation signal contains multiple attenuation pulses, the sequence can represent, for example, the temporal sequence in which the attenuation pulses follow each other within the attenuation signal, either alternatively or additionally.

[0019] The attenuation signal includes, for example, 2 to 20 attenuation pulses. The width of at least one attenuation pulse can be, for example, 0.002 milliseconds to 0.1 milliseconds.

[0020] For example, the time interval between two decaying pulses is between 0.002 milliseconds and 0.1 milliseconds. In this case, the decaying signal specifically has at least two decaying pulses.

[0021] The delay between the completion of membrane excitation by the excitation means and the first decay pulse of the decay signal may be between 0.02 milliseconds and 0.1 milliseconds. Therefore, the delay is measured, for example, from the time between the completion of the excitation signal and the first occurrence of the decay pulse of the decay signal. The sequence of decay pulses is determined, in particular, by the delay and the time intervals between decay pulses.

[0022] If the attenuation signal contains at least two attenuation pulses, the attenuation pulses in the attenuation signal have the same amplitude. For example, the attenuation pulses are generated by turning an attenuation voltage on or off. The attenuation voltage is constant, and only its sign changes, for example. Therefore, since amplitude adaptation is not required, the attenuation signal can be generated in a particularly simple and therefore cost-effective way.

[0023] Alternatively or additionally, the attenuation pulse has the same pulse shape. For example, the attenuation pulse is a rectangular pulse. Preferably, the attenuation pulse differs only in width and sign.

[0024] The adaptive means preferably includes an optimization algorithm performed on control electronic equipment. The optimization algorithm is configured, in particular, to determine an adapted damping signal depending on the amplitude of the detected afteroscillation.

[0025] In particular, all features disclosed with respect to the attenuation signal are similarly disclosed with respect to the adapted attenuation signal, and vice versa.

[0026] The optimization algorithm allows for the adaptation of the attenuation signal. To this end, the optimization algorithm obtains the amplitude of the membrane aftervibration at at least one point in time of attenuation by the attenuation means as a fitness parameter. During the intended operation of the ultrasonic transducer, the optimization algorithm generates an adapted attenuation signal from, for example, the attenuation signal used for the attenuation means to operate and the amplitude of the membrane aftervibration detected by the detection means. In particular, the detection of the amplitude of the membrane aftervibration is a prerequisite for the adaptation of the attenuation signal by the adaptation means.

[0027] For example, if new attenuation occurs after an ultrasonic transducer re-emits an ultrasonic signal, the adapted attenuation signal can be used to attenuate the aftervibrations of the membrane.

[0028] By newly detecting the amplitude of the membrane's after-vibration by the detection element, the adapted attenuation signal can then be further adapted or optimized by an adaptation element or an optimization algorithm. Therefore, the ultrasonic transducer has the advantage that it can always adapt and improve the attenuation, especially based on detecting the amplitude of the membrane's after-vibration, and can achieve particularly effective attenuation. The attenuation signal can be adapted to a plurality of vibration modes of the membrane in particular, and the after-vibration can be efficiently attenuated. In particular, the amplitude of the membrane's after-vibration attenuated by the adapted attenuation signal has a lower value than the amplitude of the membrane's after-vibration attenuated by the attenuation signal. By executing an optimization algorithm, advantageously, the attenuation of the amplitude of the after-vibration can be improved. If the optimization algorithm is executed multiple times, for example, after each excitation of the membrane by the excitation means and subsequent attenuation by the attenuation means, there is an advantage that the attenuation can be further improved during the operation of the ultrasonic transducer.

[0029] The membrane of the ultrasonic transducer can have a free vibration surface of at least 1 square millimeter. Therefore, the membrane is more robust than, for example, a piezoelectric micro-mechanical ultrasonic transducer having a membrane with a surface area of less than 1 square millimeter, and the ultrasonic transducer can be used under more unfavorable external conditions.

[0030] The attenuation means is preferably configured to excite the attenuation mode of the membrane. The attenuation signal is preferably determined by an adaptation means such that the attenuation mode reduces the after-vibration of the membrane as effectively as possible. Advantageously, exciting the attenuation mode acts on a much higher attenuation than known attenuation methods.

[0031] The present invention also relates to a method of operating an ultrasonic transducer. The ultrasonic transducer described herein can be operated, in particular, using the method of operating an ultrasonic transducer. That is, all features disclosed for the ultrasonic transducer are also disclosed for the method, and vice versa.

[0032] A method for operating an ultrasonic transducer comprising an excitation means, an attenuation means, a detection means, and an adaptation means includes the following steps:

[0033] A step of exciting a membrane using an excitation means to emit ultrasonic waves.

[0034] A step of damping the amplitude of the membrane's after-vibrations using a damping means.

[0035] A step of detecting the amplitude of the after-vibration of the membrane at at least one time point after damping by the damping means using a detection means.

[0036] A step of determining an adapted damping signal by an adaptation means based on the amplitude of the after-vibration detected by a detection means.

[0037] In particular, these steps are performed in the order described. These steps may be performed multiple times consecutively. For example, each time a step is performed, the adaptive damping signal determined in a previously performed step is used. This further adapts the damping signal each time a step is performed. For example, the damping signal is adapted using an optimization algorithm. That is, the damping signal is always improved and / or adapted to, for example, changing environmental conditions, application requirements, or measurement conditions. Thus, the method described here can dampen film aftervibrations particularly effectively.

[0038] The excitation means can excite the film with an excitation signal, and the damping means can dampen the film with a damping signal and / or an adapted damping signal. In this case, the damping signal and / or adapted damping signal preferably follow the excitation signal without delay. That is, immediately after the excitation means excites the film, the damping means dampens the after-vibrations of the film.

[0039] Furthermore, a method for measuring distance is also described. In this method of measuring distance, the ultrasonic transducer described herein is used and, in particular, operated in the manner described herein for operating the ultrasonic transducer. That is, all the features disclosed with respect to the method for operating the ultrasonic transducer and all the features disclosed with respect to the ultrasonic transducer are also disclosed with respect to the method of measuring distance, and vice versa.

[0040] In distance measurement methods, preferably exactly one ultrasonic transducer is used. That is, the ultrasonic transducer functions both as an ultrasonic transmitting element and as a detection element for ultrasonic signals reflected from the object being measured.

[0041] In transmission mode, the distance measurement method involves, for example, emitting an ultrasonic signal as a pulse from an ultrasonic transducer. When the pulse hits an object, it is reflected at least partially. In reception mode, this reflected pulse is detected, which allows for the determination of the elapsed time (Laufzeit). Since ultrasonic signals propagate at known speeds in air and water, the elapsed time can be used to calculate the distance to the measurement target.

[0042] When the distance to an object is short, for example less than 10 cm, conventional ultrasonic transducers often fail to attenuate the after-vibrations of the membrane after pulse transmission. Therefore, such ultrasonic transducers often cannot be used simultaneously as both transmitting and receiving elements.

[0043] The ultrasonic transducers described here achieve effective damping of membrane aftervibrations, making it possible to measure particularly short pulse durations, i.e., particularly short distances, using only a single ultrasonic transducer.

[0044] In particular, the distance measurement method can measure objects at a distance of 4 centimeters to 2 meters.

[0045] The method of operating the ultrasonic transducer and further advantages, favorable designs, and developmental forms of the ultrasonic transducer are evident from the embodiments shown below in conjunction with the schematic diagrams. In the drawings, identical, similar, and equivalent elements are assigned the same reference numerals. The proportions of the drawings and the elements shown therein to each other are not considered to be fundamentally to scale. Rather, individual elements may be shown in an exaggerated size for better explanation and / or understanding. [Brief explanation of the drawing]

[0046] [Figure 1] Figure 1 is a schematic diagram showing an ultrasonic transducer according to the first embodiment. [Figure 2] Figure 2 is a schematic diagram illustrating how to operate the ultrasonic transducer according to the first embodiment. [Figure 3] Figure 3 shows examples of excitation and attenuation signals used in this method. [Figure 4] Figure 4 shows an example of an attenuation signal used in this method. [Figure 5] Figure 5 shows a graph of the after-vibrations of a film attenuated by the attenuation signal described herein, compared to a film without the attenuation signal. [Figure 6] Figure 6 shows a graph of the frequency analysis of afterviolations of a film attenuated with the attenuation signal described herein, compared to a film without the attenuation signal. [Figure 7] Figures 7 and 8 show graphs of the distance measurement results using this method. [Figure 8] Figures 7 and 8 show graphs of the distance measurement results using this method. [Figure 9] Figure 9 shows a graph of the attenuated membrane motion signal. [Figure 10] Figures 10 and 11 show graphs of ultrasonic signals reflected from the object being measured and received by the ultrasonic transducer. [Figure 11] Figures 10 and 11 show graphs of ultrasonic signals reflected from the object being measured and received by the ultrasonic transducer. [Modes for carrying out the invention]

[0047] The ultrasonic transducer 1 shown in Figure 1 includes an excitation means 21, an attenuation means 22, a detection means 23, and an adaptive means 24. The excitation means 21, the attenuation means 22, and the detection means 23 are formed from a single piezoelectric element 2. The adaptive means 24 is formed from a control electronic device 3. The control electronic device 3 is configured to excite a film 4 coupled to the piezoelectric element 2. Excitation allows the film 4 to perform motion (Bewegung) 60. The piezoelectric element 2 and the film 4 are housed in a housing 11. The control electronic device 3 can also be housed in the housing 11. The control electronic device 3 is, for example, a microcontroller.

[0048] The excitation means 21 can excite the membrane 4 with an excitation signal 6 and emit an ultrasonic signal 7. After the ultrasonic signal 7 is emitted, the membrane 4 usually continues to perform after-vibrations 40.

[0049] Figure 2 shows the process of operating the ultrasonic transducer 1 of Figure 1. The excitation means 21 excites the membrane 4 to emit an ultrasonic signal 7. The damping means 22 dampens the aftervibrations 40 of the membrane 4 with a damping signal 5. In particular, after damping, the detection means 23 detects the amplitude of the aftervibrations 40. The adaptive means 24 determines the damping signal 5 depending on the amplitude of the aftervibrations 40 detected by the detection means 23. To this end, the adaptive means 24 includes an optimization algorithm that is performed on the control electronic equipment 3. If the damping signal 5 is known, for example, from having previously performed a step of the method, the adaptive means can adapt the damping signal 5 to determine an adaptive damping signal 5a. The adaptive damping signal 5a is preferably optimized by the optimization algorithm. The damping means 22 can, in particular, more effectively dampen the aftervibrations 40 of the membrane 4 with the adaptive damping signal 5a.

[0050] This method for operation can preferably be performed multiple times, for example, each time the ultrasonic signal 7 is emitted, during the intended operation of the ultrasonic transducer 1, as shown in Figure 2. In this case, the attenuation signals 5, 5a can always be optimized, resulting in particularly effective attenuation of after-vibrations 40. Furthermore, the adaptive means 24 can respond to changes in environmental conditions, measurement conditions, or application conditions, and such changes can be accommodated using the adapted attenuation signal 5a.

[0051] Figure 3 shows the excitation signal 6 used to excite the film 4 by the excitation means 21. The excitation means 6 includes rectangular pulses to which a voltage 101 is applied in a time series 102. The voltage 101 has a fixed amplitude with a sign change after each rectangular pulse.

[0052] To dampen the after-vibrations 40 of the film 4, a damping signal 5 is supplied to the damping means 22 by the control electronic equipment 3. The damping signal 5 includes at least one damping pulse 50. The control electronic equipment 3 is configured to determine at least one parameter of the damping signal from parameters of the number of damping pulses 51, the width 52 of the damping pulses 50, and the sequence 53 of the damping pulses 50. The damping signal 5 follows immediately after the excitation signal 6, in particular. That is, there is no delay between the excitation signal 6 and the damping signal 5.

[0053] Figure 4 shows the attenuation signal 5 used to operate the ultrasonic transducer 1 in the method described herein. The attenuation signal 5 includes a plurality of attenuation pulses 50, all having the same amplitude. The sign of the attenuation pulses 50 may vary and be determined, for example, by the control electronic equipment 3.

[0054] The control electronic equipment 3 determines, for example, the width 52 of the decayed pulse 50. The width 52 is obtained from the time 102 during which the voltage 101 is applied.

[0055] Furthermore, for example, the number 51 of the attenuation pulses 50, as well as the sequence 53 of the attenuation pulses 50, is determined by the control electronics. The sequence 53 of the attenuation pulses 50 indicates the sequence of attenuation points 50 in the attenuation signal 5. Furthermore, the sequence 53 indicates that the first attenuation pulse 50 occurs in the attenuation signal 5 after a waiting time 54.

[0056] Figure 5 shows the signal of the membrane motion 62 of membrane 4 attenuated by the attenuated signal 5 described herein, compared to a comparative example of the unattenuated membrane motion signal 63. The membrane motions 60 and 61 can be converted into a voltage 101 (indicated in V) by the piezoelectric effect, and this voltage is plotted in Figure 4 as a function of time 102 (indicated in ms). During excitation by the excitation means 24, the voltage 101 associated with both membrane motions 60 and 61 exceeds 10 V. The excitation signal 6 is present for approximately 0.1 ms.

[0057] In the case of membrane motion 60, the attenuation signal 5 immediately follows the excitation signal 6. The attenuation signal 5 is present for approximately 0.1 ms. Comparing the voltage 101 of the attenuated membrane motion 60 with the voltage 101 of the unattenuated membrane motion in comparative example 61, it can be seen that the voltage 101 of the attenuated membrane motion 60 is approximately two orders of magnitude lower than the voltage 101 of comparative example 61, starting from approximately 0.4 ms. Therefore, the attenuation signal 5 effectively attenuates the membrane motion 60.

[0058] The vertical dashed lines in Figure 5 show the time it takes for the ultrasonic signal 7, transmitted from the ultrasonic transducer 1 to an object 5 cm or 10 cm away, to be reflected by that object and return to the ultrasonic transducer 1. The relationship between distance and time is derived from the velocity of the ultrasonic signal 7. Whether the object is 5 cm or 10 cm away, the voltage 101 associated with the attenuated membrane motion 60 is approximately two orders of magnitude smaller than the voltage 101 associated with the unattenuated membrane motion 61. Therefore, the distance to these objects with attenuated membrane motion 60 can be effectively determined by the ultrasonic transducer.

[0059] Figure 6 shows the frequency components present in the after-vibrations 40 of the membrane 4 when the damping signal 5 is applied and, for comparison, when the damping signal 5 is not applied. In particular, the amplitude 103 of the vibration signals obtained from the membrane motions 60 and 61 is shown as a function of frequency 104 (specified in kHz). When the after-vibrations 40 are damped (see curve 70), damping mode 55 is activated. In comparative example 71, damping mode 55 is absent. Damping mode 55 effectively dampens the damped membrane motion 60 (see Figure 4).

[0060] Figure 7 shows the Hilbert envelopes of various signals measured during distance measurement by the ultrasonic transducer 1. These signals correspond to membrane motion 60, from which a corresponding voltage 101 (indicated in mV) is obtained over a time period of 102 (indicated in ms). When the Hilbert envelopes of these signals reach their maximum, the distance to the object can be determined from the elapsed time of the transmitted ultrasonic signal 7, the ultrasonic signal reflected from the object, and the velocity of the ultrasonic signal.

[0061] Figure 8 shows a graph illustrating the time 10² (in ms) for detecting the reflected ultrasonic signal as a function of the distance 10⁵ (in cm) to the associated object. From Figures 7 and 8, it can be seen that the distance from ultrasonic transducer 1 to 5 cm can be measured. In particular, only a single ultrasonic transducer is used for distance measurement.

[0062] Figure 9 shows the signal 80 of the attenuated membrane motion 60 as a function of time 102 in ms and as a voltage 101 in mV. The signal 80 is attenuated, for example, by the attenuation means 22 and then detected by the detection means 23. Figure 9 also shows that the signal 80 includes the frequency 81 of the excitation signal 6 and the attenuation mode 55. For this purpose, the signal 80 is filtered by a narrowband bandpass filter around the attenuation mode 55 and the frequency 81 of the excitation signal 6. As can be seen from Figure 9, the signal 80 includes both the excitation signal 6 and the attenuation mode 55.

[0063] Figure 10 shows the signal 90 of the ultrasonic signal reflected from the object being measured, received by the ultrasonic transducer 1. The reflected ultrasonic signal generates a membrane motion 60 that can be expressed as a voltage 101 that can be expressed in mV via the piezoelectric effect. The signal 90 includes signals with the frequency 91 and attenuation mode 55 of the excitation signal 6, respectively, which can be represented from the signal 90 as in Figure 9. As can be seen from Figure 10, the attenuation mode 55 occupies only a small portion of the signal 90. Therefore, the attenuation mode 55 has only a slight effect on the distance measurement result. Furthermore, the maximum value of the envelope of the signal 90 can be seen, thereby allowing the distance of the object to be determined. In this example, the distance of the object from the ultrasonic transducer is 15 cm.

[0064] Unlike Figure 10, Figure 11 shows the comparison signal 95 of the ultrasonic signal reflected from the object being measured, in a state where no after-vibrations of the membrane due to the attenuation signal 5 are occurring. As can be seen from Figure 11, the comparison signal 95 is substantially determined by the frequency 96 of the excitation signal 6, and the envelope of the comparison signal 95 decreases continuously. This makes it impossible to determine the distance of the object from the ultrasonic transducer.

[0065] Furthermore, a comparison with Figure 10 reveals that the comparison signal 95 has an amplitude an order of magnitude higher than signal 90. This means that all the information in the comparison signal 95 that could determine the distance of the object is obscured by the after-vibrations of the membrane 4, making it impossible to determine the distance of the object. [Explanation of Symbols]

[0066] 1. Ultrasonic transducer (Ultraschallwandler) 2. Piezoelectric element 3. Control Electronics (Steuerungselektronik) 4 Membrane 5. Attenuation signal (Daempfungssignal) 5a Adaptive attenuation signal (angepasstes Daempfungssignal) 6. Excitation signal 7 Ultrasound signal 11 Housing (Gehaeuse) 21 Excitation methods (Anregungsmittel) 22 Damping means (Daempfungsmittel) 23. Detection means (Erfassungsmittel) 24. Adaptation Measures (Anpassungsmittel) 40. Aftervibrations of the membrane (Nachschwingung der Membran) 50 Attenuation pulses (Daempfungspuls) 51. Number of decaying pulses (Anzahl von Daempfungspulsen) 52. Width of decaying pulses (Breite des Daempfungspulses) 53. Sequence of decaying pulses (Abfolge von Daempfungspulsen) 54 Waiting time (Wartezeit) 55 Attenuation Mode (Daempfungsmode) 60 Membrane movement 61. Comparative example of membrane motion (Membranbewegung) 62 Membrane movement signal 63. Comparative example of membrane motion signals (Membranbewegungs-Signals) 70. Frequency of membrane motion (Frequenz der Membranbewegung) 71. Frequency of Comparative Examples (Frequenz des Vergleichsbeispiels) 80. Signal of attenuated membrane motion 81, 91, 96 Excitation signal frequencies (Frequenz des Anregungssignals) 90 The ultrasonic signal reflected from the object being measured. Mesenden Objekt reflektierten Ultraschallsignal) 95 Comparison signal (Vergleichssignal) 101 Stress (Spannung) 102 hours (Zeit) 103 Amplitude 104 Frequenz 105 Distance (Entfernung)

Claims

1. An ultrasonic transducer (1) comprising an excitation means (21), an attenuation means (22), a detection means (23), an adaptation means (24), and a membrane (4), The excitation means (21) is configured to excite the membrane (4) to emit ultrasonic waves (7), The damping means (22) is configured to dampen the after-vibrations (40) of the film (4) that occur after excitation with a damping signal (5). The detection means (23) is configured to detect the amplitude of the aftervibration (40) of the film (4), The adaptive means (24) is configured to determine the damping signal (5) depending on the detected amplitude of the after-vibration (40). Ultrasonic transducer.

2. The excitation means (21), the attenuation means (22), and the detection means (23) each have a piezoelectric element (2). The ultrasonic transducer according to claim 1.

3. The aforementioned attenuation signal (5) is provided by the control electronic device (3). The ultrasonic transducer according to claim 1 or 2.

4. The excitation means (21) is configured to excite the film (4) with an excitation signal (6), and the excitation signal (6) is provided from the control electronic device (3). The ultrasonic transducer according to claim 3.

5. The attenuation signal (5) is phase-shifted by 180° relative to the excitation signal (6). The ultrasonic transducer according to claim 4.

6. The attenuation signal (5) and the excitation signal (6) have the same amplitude. The ultrasonic transducer according to claim 4 or 5.

7. The attenuation signal (5) has at least one attenuation pulse (50), The adaptive means (24) is configured to determine at least one parameter of the damping signal (5) depending on the detected amplitude of the after-vibration (40), The parameter is at least one of the number (51) of the attenuation pulses (50), the width (52) of the at least one attenuation pulse (50), and the sequence (53) of the at least one attenuation pulse (50). An ultrasonic transducer according to any one of claims 1 to 6.

8. The attenuation signal (5) includes an attenuation pulse (50) of a number (51) between 2 and 10, The ultrasonic transducer according to claim 7.

9. The width (52) of the at least one decayed pulse (5) is 0.02 milliseconds or more and 0.1 milliseconds or less. The ultrasonic transducer according to claim 7 or 8.

10. The attenuation signal (5) has at least two attenuation pulses (50), and the time interval (53) between the two consecutive attenuation pulses (50) is 0.02 milliseconds or more and 0.1 milliseconds or less. The ultrasonic transducer according to any one of claims 7 to 9.

11. The waiting time (54) between the endpoint of excitation by the film (6) by the excitation means (21) and the first decay pulse (50) of the decay signal (5) is 0.02 milliseconds or more and 0.1 milliseconds or less. An ultrasonic transducer according to any one of claims 7 to 10.

12. The attenuation signal (5) has at least two attenuation pulses (50), and the attenuation pulses (50) of the attenuation signal (5) have the same amplitude and / or the same pulse shape. An ultrasonic transducer according to any one of claims 7 to 11.

13. The adapting means (24) comprises an optimization algorithm executed on a control electronic device (3), the optimization algorithm configured to determine an adapted damping signal (5a) depending on the detected amplitude of the after-vibration (40). An ultrasonic transducer according to any one of claims 1 to 12.

14. The amplitude of the after-vibration (40) of the membrane (6) attenuated by the applied attenuation signal (5a) is lower than the amplitude of the after-vibration (40) of the membrane (6) attenuated by the attenuation signal (5). The ultrasonic transducer according to claim 13.

15. The film (4) has a free vibration surface of at least 1 square millimeter. An ultrasonic transducer according to any one of claims 1 to 14.

16. The damping means (22) is configured to excite the damping mode (55) of the film (6). An ultrasonic transducer according to any one of claims 1 to 15.

17. A method for operating an ultrasonic transducer (1) comprising an excitation means (21), an attenuation means (22), a detection means (23), and an adaptation means (24), The steps include: exciting the membrane (6) with the excitation means (21) to emit ultrasonic waves (7), The steps include reducing the amplitude of the after-vibration (40) of the membrane (4) using the damping means (22), The steps include detecting the amplitude of the after-vibration (40) of the membrane (4) at at least one time point after damping by the damping means using the detection means (23), The step includes determining an attenuation signal (5a) adapted by the adaptation means (24) based on the amplitude of the after-vibration (40) detected by the detection means, method.

18. The above steps are performed multiple times in succession in the specified order. The adapted attenuation signal determined in a previously executed step is used in each execution of the step. The method according to claim 17.

19. The excitation means (21) excites the film (4) with the excitation signal (6) The damping means (22) dampens the amplitude of the aftervibration (40) of the membrane (4) by the damping signal (5), The attenuation signal (5) follows the excitation signal (6) without any waiting time. The method according to claim 17 or 18.

20. A method for measuring the distance to be measured, A method for measuring an object to be measured within a distance of 4 cm to 2 m using one ultrasonic transducer (1) according to any one of claims 1 to 19.

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