Ultrasonic transducer, method for operating an ultrasonic transducer, and method for measuring a distance

Abstract

The invention relates to an ultrasonic transducer (1) which comprises an excitation means (21), a damping means (22), a detection means (23), an adaptation means (24), and a diaphragm (4). The excitation means (21) is designed to excite the diaphragm (4) such that it transmits an ultrasonic signal (7). The damping means (22) is designed to dampen, by means of a damping signal (5), a reverberation (40) of the diaphragm (4) occurring after the excitation. The detection means (24) is designed to detect the amplitude of the reverberation (40) of the diaphragm (4), and the adaptation means (24) is designed to ascertain the damping signal (5) on the basis of the detected amplitude of the reverberation (40).

Description

[0001] Description

[0002] Ultrasonic transducer, method for operating an ultrasonic transducer and method for distance measurement

[0003] The invention relates to an ultrasonic transducer and a method for operating an ultrasonic transducer and a method for distance measurement.

[0004] Piezoelectric ultrasonic transducers are used for both transmitting and receiving ultrasonic signals and are used, for example, as distance sensors in motor vehicles. However, such ultrasonic transducers typically continue to emit ultrasound even after all excitation of the ultrasonic signal has ceased. The reason for this is primarily the oscillation of a membrane of the ultrasonic transducer, which generates the ultrasonic signals. This oscillation is also referred to as "ringing" and makes it difficult to detect an ultrasonic signal using the same membrane.

[0005] Ultrasonic transducers and methods for operating ultrasonic transducers are known from the publications US 4,580,251, US 6,731,596 B2, as well as Lio 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.

[0006] One problem to be solved is to provide an improved ultrasonic transducer and an improved method for operating an ultrasonic transducer. These problems are solved by an object with the

[0007] Features of independent patent claim 1 and by a method having the features of patent claim 17.

[0008] An ultrasonic transducer is proposed which has an excitation means, a damping means, a detection means and an adaptation means as well as a membrane. The excitation means is designed to excite the membrane to emit an ultrasonic signal. The damping means is designed to dampen any post-oscillation of the membrane occurring after excitation by means of a damping signal. The detection means is designed to detect the amplitude of the post-oscillation of the membrane. The adaptation means is designed to determine the damping signal as a function of the detected amplitude of the post-oscillation.

[0009] By detecting the amplitude of the post-oscillation, it is possible, in particular, to use the matching means to set the damping signal in such a way that the post-oscillation of the diaphragm can be effectively damped. Since the amplitude of the post-oscillation is explicitly measured, it is possible to react dynamically to changes in, for example, environmental conditions or application requirements, and to select an appropriate damping for the post-oscillation of the diaphragm.

[0010] During normal operation of the ultrasonic transducer, the excitation means can excite the membrane to emit an ultrasonic signal. A post-oscillation of the membrane, which occurs in particular after the excitation of the membrane has ended, can be damped by the damping means, wherein the damping signal is applied, for example, to the membrane. In particular, after the damping signal has been applied, an amplitude of the post-oscillation can be detected by means of the detection element. With other

[0011] In other words, the amplitude of the post-oscillation can be measured. For example, the post-oscillation of the membrane is converted into a voltage by means of the piezoelectric effect, from which the amplitude of the post-oscillation of the membrane can be derived.

[0012] The damping signal can be set using the matching element. If, for example, the amplitude of the diaphragm's post-oscillation is measured during operation before the damping signal is set, the damping signal can advantageously be set such that the amplitude of the diaphragm's post-oscillation is reduced or minimized. This means that by detecting the amplitude of the diaphragm's post-oscillation, the ultrasonic transducer can set the damping signal as optimally as possible, so that the diaphragm's post-oscillation is minimized as much as possible. The ultrasonic transducer can therefore react dynamically to changing ambient conditions, application requirements, measurement conditions, or the like, and set the damping accordingly. This advantageously allows the ultrasonic transducer to be used under a variety of external conditions and when measuring distances over a comparatively wide range.

[0013] In particular, the excitation means, the damping means and the detection means comprise a piezoelectric element. For example, the excitation means and the damping means and / or the detection means are formed by the piezoelectric element. In particular, the excitation means, the damping means and the detection means are formed by the same piezoelectric

[0014] element . This means that the ultrasonic transducer comprises in particular a piezoelectric element which serves as the

[0015] Excitation means, damping means, and detection means act and preferably fulfill the functions of the excitation means, the damping means, and the detection means. The piezoelectric element can be a piezoelectric disc.

[0016] It is possible for at least one of the excitation means, the damping means, and the detection means to comprise control electronics. For example, in the case of the excitation element and the damping element, the control electronics provides a signal for the piezoelectric element or, in the case of the detection means, evaluates a signal from the piezoelectric element.

[0017] It is possible for the piezoelectric element to be connected to the control electronics of the ultrasonic transducer. For example, the control electronics comprise at least one of the following electronic components: a microcontroller, an application-specific integrated circuit (ASIC), and a field-programmable gate array (FPGA).

[0018] The damping signal, for example, is provided to the damping means by means of the control electronics. For example, the damping means is electrically connected to the control electronics. In particular, the excitation means is designed to excite the membrane by means of an excitation signal. The excitation signal is provided, for example, by the control electronics. The excitation signal preferably essentially determines the ultrasonic signal emitted by the membrane and thus by the ultrasonic transducer. By defining the excitation signal, the shape, length, frequencies, etc. of the ultrasonic signal can thus be defined.

[0019] The damping signal can be 180° out of phase with the excitation signal. The phase shift of the damping signal enables efficient damping.

[0020] The excitation signal and the damping signal can have the same amplitude. This allows for particularly simple operation of the ultrasonic transducer, since the excitation signal and the damping signal can be generated in essentially the same way.

[0021] It is possible for the damping signal to comprise at least one damping pulse. The adaptation means is particularly configured to determine at least one of the following parameters of the damping signal as a function of the detected amplitude of the post-oscillation: number of damping pulses, width of the at least one damping pulse, sequence of the at least one damping pulse.

[0022] It is possible, for example, for the damping signal to have one or more damping pulses. The width of the at least one damping pulse is determined, in particular, based on the time during which the damping signal has the damping pulse. For example, the damping pulses are rectangular pulses. This means that during the time during which the damping signal displays the damping pulse, the damping signal has a predetermined voltage that is not equal to zero. The time period during which the damping signal has this voltage determines, in particular, the width of the damping pulse.

[0023] For example, if the damping signal has only one damping pulse, the sequence of the one damping pulse can indicate the time period after the termination of the excitation of the membrane with the excitation medium that the damping pulse occurs. If the damping signal comprises multiple damping pulses, the sequence, for example, alternatively or additionally indicates the temporal sequence in which the damping pulses follow one another in the damping signal.

[0024] The damping signal comprises, for example, between two and 20 damping pulses. The width of at least one damping pulse can, for example, be between 0.002 milliseconds and 0.1 milliseconds.

[0025] For example, the time interval between two damping pulses is between 0.002 milliseconds and 0.1 milliseconds. In this case, the damping signal comprises, in particular, at least two damping pulses.

[0026] The waiting time between the end of the excitation of the membrane with the excitation agent and the first damping pulse of the damping signal can be between 0.02 milliseconds and 0.1 milliseconds inclusive. The waiting time is thus measured, for example, from the time between the end of the excitation signal and the first occurrence of a damping pulse of the damping signal. The sequence of the damping pulses is determined, in particular, by the waiting time and the time interval between the damping pulses.

[0027] If the damping signal comprises at least two damping pulses, the damping pulses of the damping signal have the same amplitude. For example, the damping pulses are generated by switching a damping voltage on and off. The damping voltage is constant and varies, for example, only in sign. This makes the damping signal particularly simple and therefore cost-effective to generate, since no amplitude adjustment is necessary.

[0028] Alternatively or additionally, the damping pulses have the same pulse shape. For example, the damping pulses are rectangular pulses. The damping pulses preferably differ from one another only in their width and sign.

[0029] Preferably, the adaptation means comprises an optimization algorithm implemented on the control electronics. The optimization algorithm is particularly configured to determine an adapted damping signal as a function of the detected amplitude of the post-oscillation.

[0030] In particular, all features disclosed for the damping signal are analogously disclosed for the adapted damping signal and vice versa. The optimization algorithm makes it possible to adapt the damping signal. For this purpose, the optimization algorithm receives the amplitude of the membrane's post-oscillation at at least one point in time before damping by means of the damping means as a fitness parameter. During normal operation of the ultrasonic transducer, the optimization algorithm creates an adapted damping signal, for example from the damping signal used to operate the damping means and the amplitude of the membrane's post-oscillation detected by the detection means. In particular, the detection of the amplitude of the membrane's post-oscillation is a prerequisite for the damping signal to be able to be adapted by means of the adaptation means.

[0031] If damping is repeated, for example after a renewed transmission of an ultrasonic signal by the ultrasonic transducer, the damping of the membrane's post-oscillation can be carried out with the adapted damping signal.

[0032] By again detecting the amplitude of the membrane's post-oscillation by the detecting element, the adjusted damping signal can subsequently be further adjusted or optimized using the adjusting element or the optimization algorithm. Thus, advantageously, particularly due to the detection of the amplitude of the membrane's post-oscillation, the ultrasonic transducer can always adapt and improve the damping, whereby particularly effective damping can be achieved. The damping signal can in particular be adapted to a plurality of vibration modes of the membrane and damping of the post-oscillation is efficiently possible. In particular, an amplitude of the membrane's post-oscillation damped by means of the adjusted damping signal has a lower value than an amplitude of the membrane's post-oscillation damped by means of the damping signal.By executing the optimization algorithm, the damping of the amplitude of the post-oscillation can be advantageously improved. If the optimization algorithm is executed multiple times, for example, after each excitation of the membrane by the excitation agent and subsequent damping by the damping agent, the damping can be advantageously continuously improved during operation of the ultrasonic transducer.

[0033] The membrane of the ultrasonic transducer can have a freely vibrating surface of at least one square millimeter. This makes the membrane more robust and allows the ultrasonic transducer to be used under less favorable external conditions than, for example, a piezoelectric micromechanical ultrasonic transducer, which has a membrane with a surface area of ​​less than one square millimeter.

[0034] The damping means is preferably configured to excite a damping mode of the membrane. The damping signal is preferably determined by the adaptation means such that the damping mode reduces the membrane's post-oscillation as effectively as possible. Advantageously, exciting a damping mode results in significantly higher damping than known damping methods.

[0035] Furthermore, a method for operating a

[0036] ultrasonic transducer. The one described here

[0037] The ultrasonic transducer can be operated, in particular, using the method for operating an ultrasonic transducer. This means that all features disclosed for the ultrasonic transducer are also disclosed for the method, and vice versa.

[0038] The method for operating an ultrasonic transducer , which has , for example , an excitation means , a damping means , a detection means and an adaptation means , comprises in particular the following steps :

[0039] Stimulating the membrane to emit an ultrasonic wave using the excitation agent.

[0040] Damping an amplitude of the post-oscillation of the membrane by means of the damping agent.

[0041] Detecting the amplitude of the post-oscillation of the membrane at at least one time after damping by the damping means by means of the detecting means.

[0042] Determining an adapted damping signal based on the amplitude of the post-oscillation detected by the detection means by means of the adaptation means.

[0043] These steps are carried out in particular in the specified order. Preferably, these steps are carried out several times in succession. For example, each time the steps are carried out, the adjusted damping signal determined in the previous step is used. This means that the damping signal is further adjusted each time the steps are carried out. For example, the damping signal is adjusted using the optimization algorithm. This means that the damping signal is constantly improved and / or adjusted to, for example, changed ambient conditions, application requirements or measurement conditions. The method described here therefore enables particularly effective damping of the membrane's post-oscillation.

[0044] The excitation means can excite the membrane with an excitation signal, and the damping means can dampen the membrane using the damping signal and / or the adapted damping signal. The damping signal and / or the adapted damping signal preferably follows the excitation signal without a waiting time. This means that after the excitation means has excited the membrane, the damping means immediately dampens the membrane's post-oscillation.

[0045] Furthermore, a method for distance measurement is specified. The method for distance measurement uses an ultrasonic transducer described here, which is operated in particular with a method for operating an ultrasonic transducer described here. This means that all features disclosed for the method for operating the ultrasonic transducer and for the ultrasonic transducer are also disclosed for the method for distance measurement, and vice versa.

[0046] Preferably, the distance measurement method uses exactly one ultrasonic transducer. This means that the ultrasonic transducer serves both as a transmitter element for an ultrasonic wave and as a detector element for an ultrasonic signal reflected by the object to be measured.

[0047] In a broadcasting operation, the procedure for

[0048] For distance measurement, for example, an ultrasonic signal is emitted as a pulse from the ultrasonic transducer. After the pulse hits an object, it is at least partially reflected back. In receiving mode, this reflected pulse is detected, allowing a propagation time to be determined. Since ultrasonic signals propagate in air and water at known sound speeds, the distance to the target being measured can be calculated using the propagation time.

[0049] If the distance to the object is short, for example less than 10 centimeters, the oscillation of the membrane in conventional ultrasonic transducers has typically not yet decayed after the pulse has been emitted, which is why such ultrasonic transducers often cannot be used as a transmitting element and as a receiving element at the same time.

[0050] With the ultrasonic transducer described here, it is possible to measure particularly short pulse propagation times, i.e. particularly short distances, with only a single ultrasonic transducer, since effective damping of the membrane's post-oscillation is achieved.

[0051] In particular, the distance measurement method can be used to measure objects at a distance of between 4 centimeters and 2 meters.

[0052] Further advantages and advantageous embodiments and further developments of the method for operating an ultrasonic transducer and of the ultrasonic transducer will become apparent from the exemplary embodiments presented below in conjunction with schematic drawings. Identical, similar, and similarly acting elements are provided with the same reference symbols in the figures. The figures and the relative sizes of the elements shown in the figures are not to be considered to scale. Rather, individual elements may be exaggerated for clarity and / or clarity. They show:

[0053] Figure 1 shows an ultrasonic transducer according to a first embodiment,

[0054] Figure 2 is a schematic illustration of a method for operating an ultrasonic transducer according to a first embodiment,

[0055] Figure 3 shows an example of an excitation signal and a damping signal as used in the method described here,

[0056] Figure 4 shows an example of an attenuation signal as used in the method described here,

[0057] Figure 5 is a graphical representation of a post-oscillation of a membrane which is produced with a

[0058] damping signal is damped, compared to a membrane without damping signal,

[0059] Figure 6 is a graphical representation of a frequency analysis of a post-oscillation of a membrane damped with a damping signal described here, compared to a membrane without a damping signal,

[0060] Figures 7 and 8 are graphical representations of a result of a distance measurement using a method described here, Figure 9 is a graphical representation of a signal of a damped membrane movement,

[0061] Figures 10 and 11 are graphical representations of a signal of an ultrasonic signal reflected from an object to be measured and received by the ultrasonic transducer.

[0062] The ultrasonic transducer 1 according to Figure 1 has an excitation means 21, a damping means 22, a detection means 23 and an adaptation means 24. The excitation means 21, the damping means 22 and the detection means 23 are formed with a piezoelectric element 2. The adaptation means 24 is formed with control electronics 3. The control electronics 3 are designed to excite a membrane 4 coupled to the piezoelectric element 2. As a result of an excitation, the membrane 4 can perform a movement 60. The piezoelectric element 2 and the membrane 4 are arranged in a housing 11. It is possible that the control electronics 3 is also arranged in the housing 11. The control electronics 3 is, for example, a microcontroller.

[0063] The excitation means 21 can excite the membrane 4 with an excitation signal 6, so that an ultrasonic signal 7 is emitted. After the ultrasonic signal 7 is emitted, the membrane 4 typically continues to oscillate, thus continuing to perform a post-oscillation 40.

[0064] Figure 2 illustrates a method for 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 post-oscillation 40 of the membrane 4 by means of a damping signal 5. In particular after the damping, the detection means 23 detects an amplitude of the post-oscillation 40. The adaptation means 24 defines the damping signal 5 as a function of the amplitude of the post-oscillation 40 detected by the detection means 23. For this purpose, the adaptation means 24 comprises an optimization algorithm executed on the control electronics 3. If a damping signal 5 is already known, for example from a previous run through the steps of the method, the adaptation means can adapt the damping signal 5 and define an adapted damping signal 5a. The adapted damping signal 5a is preferably optimized by the optimization algorithm.By means of the adapted damping signal 5a, the damping means 22 can in particular carry out a more effective damping of the post-oscillation 40 of the membrane 4.

[0065] The operating method can preferably be carried out multiple times during normal operation of the ultrasonic transducer 1, for example, each time an ultrasonic signal 7 is emitted, as indicated in Figure 2. In this case, the damping signal 5, 5a can be continuously optimized, thus enabling particularly effective damping of the post-oscillation 40. Furthermore, the adaptation means 24 can react to changing ambient conditions, measurement conditions, or application requirements in order to be able to respond to such changes with an adapted damping signal 5a.

[0066] Figure 3 illustrates an excitation signal 6 with which the

[0067] Membrane 4 is excited by means of the excitation agent 21. The

[0068] Excitation means 6 comprises rectangular pulses that are applied in a time sequence 102 with a voltage 101. The voltage 101 has a fixed amplitude, with a sign changing after each rectangular pulse.

[0069] In order to dampen the post-oscillation 40 of the membrane 4, a damping signal 5 for the damping means 22 is provided by means of the control electronics 3. The damping signal 5 comprises at least one damping pulse 50. The control electronics 3 is configured to determine at least one parameter of the damping signal from the following parameters: number 51 of the damping pulses, width

[0070] 52 of the damping pulses 50 and sequence 53 of the damping pulse 50. In particular, the damping signal 5 immediately follows the excitation signal 6. This means that there is no waiting time between the excitation signal 6 and the damping signal 5.

[0071] Figure 4 illustrates a damping signal 5 as used in the method described here for operating an ultrasonic transducer 1. The damping signal 5 comprises a plurality of damping pulses 50, all of which have the same amplitude. The signs of the damping pulses 50 can vary and are determined, for example, by the control electronics 3.

[0072] For example, the control electronics 3 determines the width 52 of the damping pulses 50. The width 52 results from the time 102 during which the voltage 101 is applied.

[0073] Furthermore, for example, the number 51 of the damping pulses 50 is determined by the control electronics and a sequence

[0074] 53 of the damping pulses 50. The sequence 53 of the damping pulses 50 indicates the temporal sequence in which the damping points 50 occur in the damping signal 5. Furthermore, the sequence 53 indicates the waiting time 54 after which a first damping pulse 50 occurs in the damping signal 5.

[0075] Figure 5 shows the signal of a membrane movement 62 of a membrane 4, which is damped with a damping signal 5 described here, in comparison to a comparative example of a membrane movement signal 63 that is not damped. The membrane movements 60, 61 can be converted via the piezoelectric effect into a voltage 101 (specified in V), which is plotted in Figure 4 as a function of time 102 (specified in ms). During excitation with the excitation means 24, a voltage 101 associated with both membrane movements 60, 61 is over 10 V. The excitation signal 6 is present for approximately 0.1 ms.

[0076] In the case of diaphragm movement 60, the damping signal 5 immediately follows the excitation signal 6. The damping signal 5 is present for approximately 0.1 ms. A comparison of the curves of the voltages 101 of the damped diaphragm movement 60 and the undamped diaphragm movement of the comparative example 61 shows that, from approximately 0.4 ms, the voltage 101 of the damped diaphragm movement 60 is approximately two orders of magnitude lower than the voltage 101 of the comparative example 61. The damping signal 5 therefore effectively dampens the diaphragm movement 60.

[0077] Dashed vertical lines in Figure 5 illustrate times at which, after the transmission of an ultrasonic signal 7 from the ultrasonic transducer 1 to an object 5 cm or 10 cm away, an ultrasonic signal reflected by the object reaches the ultrasonic transducer 1 again. A relationship between distance and time results from the

[0078] Speed ​​of sound of the ultrasonic signal 7. For both an object at a distance of 5 cm and at a distance of 10 cm, the voltage 101 associated with the damped membrane movement 60 is approximately two orders of magnitude smaller than the voltage 101 associated with the undamped membrane movement 61. Thus, the distance to these objects with a damped membrane movement 60 can be effectively determined using the ultrasonic transducer.

[0079] Figure 6 illustrates which frequency components are present in the post-oscillation 40 of the membrane 4 when the damping signal 5 is applied and in a comparison example in which no damping signal 5 is applied. In this case, an amplitude 103 of an oscillation signal, which is obtained in particular from the membrane movements 60, 61, is shown as a function of the frequency 104 (specified in kHz). When the post-oscillation 40 is damped (compare curve 70), a damping mode 55 is excited. The damping mode 55 is not present in the comparison example 71. The damped membrane movement 60 is effectively damped by the damping mode 55 (compare Figure 4).

[0080] Figure 7 illustrates a Hilbert envelope for various signals measured during a distance measurement using the ultrasonic transducer 1. The signals correspond to membrane movements 60, from which an associated voltage 101 (specified in mV) is obtained over a time 102 (specified in ms). At a maximum of the Hilbert envelope of these signals, the distance of the object is determined from the propagation time of an emitted ultrasonic signal 7 and an ultrasonic signal reflected from the object to be measured, together with the speed of sound of the ultrasonic signal.

[0081] Figure 8 shows a graphical representation in which a time 102 (given in ms) at which the reflected ultrasonic signal is detected as a function of the distance 105 (given in cm) of the corresponding objects.

[0082] Figures 7 and 8 show that distances of up to 5 cm can be measured by the ultrasonic transducer 1. In particular, only a single ultrasonic transducer is used for distance measurement.

[0083] Figure 9 shows a signal 80 of a damped membrane movement 60 as a voltage 101 specified in mV as a function of time 102 specified in ms. The signal 80 is detected by the detection means 23, for example after damping with the damping means 22. Figure 9 further illustrates that the signal 80 contains a frequency 81 of the excitation signal 6 and the damping mode 55. For this purpose, the signal 80 was filtered with a narrowband bandpass filter around the frequency 81 of the excitation signal 6 and the damping mode 55. As can be seen in Figure 9, the signal 80 contains both the excitation signal 6 and the damping mode 55.

[0084] Figure 10 shows a signal 90 of an ultrasonic signal that was reflected from an object to be measured and is received by the ultrasonic transducer 1. The reflected ultrasonic signal generates a membrane movement 60 that can be represented as a voltage 101 in mV via the piezoelectric effect. The signal 90 contains a signal each with the frequency 91 of the excitation signal 6 and the damping mode 55, which can be represented from the signal 90 in a similar way to Figure 9. As can be seen in Figure 10, the damping mode 55 only has a small proportion in the signal 90. The damping mode 55 therefore only has an insignificant influence on the result of a distance measurement. Furthermore, a maximum of an envelope of the signal 90 can be seen, with which a distance of the object can be determined. In the present example, the distance of the object from the ultrasonic transducer is 15 cm.

[0085] In contrast to Figure 10, Figure 11 shows a comparison signal 95 of an ultrasonic signal reflected from the object to be measured, without any post-oscillation of the membrane 4 having occurred due to the damping signal 5. As can be seen in Figure 11, the comparison signal 95 is essentially determined by a frequency 96 of the excitation signal 6, and an envelope of the comparison signal 95 decreases continuously. Thus, the distance of the object from the ultrasonic transducer cannot be determined.

[0086] Furthermore, the comparison with Figure 10 shows that the comparison signal 95 has an amplitude that is one order of magnitude higher than the signal 90. This means that all information of the comparison signal 95, from which the distance of the object could be determined, is covered by the post-oscillation of the membrane 4, so that the distance of the object cannot be determined. Reference symbol

[0087] 1 ultrasonic transducer

[0088] 2 piezoelectric element

[0089] 3 Control electronics

[0090] 4 Membran

[0091] 5 Damping signal

[0092] 5a adjusted damping signal

[0093] 6 Excitation signal

[0094] 7 Ultrasound signal

[0095] 11 housings

[0096] 21 stimulants

[0097] 22 Damping agents

[0098] 23 means of recording

[0099] 24 adjustment means

[0100] 40 Membrane reverberation

[0101] 50 damping pulses

[0102] 51 Number of damping pulses

[0103] 52 Width of the damping pulse

[0104] 53 sequence of damping pulses

[0105] 54 Waiting time

[0106] 55 Damping mode

[0107] 60 Membrane movement

[0108] 61 Comparative example of a membrane movement

[0109] 62 Signal of a membrane movement

[0110] 63 Comparative example of a membrane movement

[0111] Signals

[0112] 70 Frequency of membrane movement

[0113] 71 Frequency of the comparison example

[0114] 80 Signal of damped membrane movement

[0115] 81 , 91 , 96 Frequency of the excitation signal

[0116] 90 Signal of the ultrasonic signal reflected from an object to be measured 95 Comparison signal

[0117] 101 Tension

[0118] 102 Time

[0119] 103 Amplitude 104 Frequency

[0120] 105 Distance

Claims

Patent claims 1. Ultrasonic transducer (1) comprising an excitation means (21), a damping means (22), a detection means (23), an adaptation means (24) and a membrane (4), wherein - the excitation means (21) is designed to excite the membrane (4) to emit an ultrasonic wave (7), - the damping means (22) is designed to dampen a post-oscillation (40) of the membrane (4) occurring after excitation by means of a damping signal (5), - the detection means (23) is designed to detect the amplitude of the post-oscillation (40) of the membrane (4), and - the adaptation means (24) is designed to determine the damping signal (5) as a function of the detected amplitude of the post-oscillation (40).

2. Ultrasonic transducer (1) according to claim 1, wherein the excitation means (21), the damping means (22) and the detection means (23) comprise a piezoelectric element (2).

3. Ultrasonic transducer (1) according to one of the preceding claims, wherein the attenuation signal (5) is provided by control electronics (3).

4. Ultrasonic transducer (1) according to claim 3, wherein the excitation means (21) is arranged to excite the membrane (4) by means of an excitation signal (6) and the Excitation signal (6) is provided by the control electronics (3).

5. Ultrasonic transducer (1) according to claim 4, wherein the attenuation signal (5) is 180° out of phase with the excitation signal (6).

6. Ultrasonic transducer (1) according to claim 4 or 5, wherein the damping signal (5) and the excitation signal (6) have the same amplitude.

7. Ultrasonic transducer (1) according to one of the preceding claims, wherein the damping signal (5) comprises at least one damping pulse (50) and the adaptation means (24) is configured to determine at least one of the following parameters of the damping signal (5) as a function of the detected amplitude of the post-oscillation (40): number (51) of the damping pulses (50), width (52) of the at least one damping pulse (50), sequence (53) of the at least one damping pulse (50).

8. Ultrasonic transducer (1) according to claim 7, wherein the Damping signal (5) a number (51) of including 2 to 10 damping pulses (50) inclusive.

9. Ultrasonic transducer (1) according to claim 7 or 8, wherein a width (52) of the at least one damping pulse (5) is between 0.02 and 0.1 inclusive milliseconds.

10. Ultrasonic transducer (1) according to one of claims 7 to 9, wherein the attenuation signal (5) has at least two damping pulses (50) and a time period (53) between two successive damping pulses (50) is between 0.02 and 0.1 milliseconds inclusive.

11. Ultrasonic transducer (1) according to one of claims 7 to 10, wherein a waiting time (54) between an end of the excitation by the membrane (6) by means of the excitation means (21) and a first damping pulse (50) of the damping signal (5) is between 0.02 and 0.1 milliseconds inclusive.

12. Ultrasonic transducer (1) according to one of claims 7 to 11, wherein the damping signal (5) comprises at least two damping pulses (50) and the damping pulses (50) of the damping signal (5) have an identical amplitude and / or an identical pulse shape.

13. Ultrasonic transducer (1) according to one of the preceding claims, wherein the adaptation means (24) comprises an optimization algorithm executed on a control electronics (3), and the optimization algorithm is designed to determine an adapted damping signal (5a) as a function of the detected amplitude of the post-oscillation (40).

14. Ultrasonic transducer (1) according to claim 13, wherein an amplitude of the post-oscillation (40) of the membrane (6) damped by means of the adapted damping signal (5a) has a lower value than an amplitude of the post-oscillation (40) of the membrane (6) damped by means of the damping signal (5).

15. Ultrasonic transducer (1) according to one of the preceding claims, wherein the membrane (4) has a freely vibrating surface of at least one square millimeter.

16. Ultrasonic transducer (1) according to one of the preceding claims, wherein the damping means (22) is arranged to excite a damping mode (55) of the membrane (6).

17. A method for operating an ultrasonic transducer (1) comprising an excitation means (21), a damping means (22), a detection means (23) and an adaptation means (24), comprising the following steps: - Excitation of the membrane (6) to emit an ultrasonic wave (7) by means of the excitation means (21), - damping an amplitude of the post-oscillation (40) of the membrane (4) by means of the damping means (22), - detecting the amplitude of the post-oscillation (40) of the membrane (4) at least at one point in time after the damping by the damping means by means of the detecting means (23), and - Determining an adapted damping signal (5a) on the basis of the amplitude of the post-oscillation (40) detected by the detection means by means of the adaptation means (24).

18. The method according to claim 17, wherein the steps are carried out several times in succession in the specified order and wherein in each execution of the steps the adapted attenuation signal determined in the previous execution step is used.

19. Method according to claim 17 or 18, in which - the excitation means (21) excites the membrane (4) with an excitation signal (6), - the damping means (22) reduces the amplitude of the post-oscillation (40) of the membrane (4) by means of the damping signal (5) and - the damping signal (5) follows the excitation signal (6) without a waiting time.

20. Method for distance measurement, in which exactly one Ultrasonic transducer (1) according to one of claims 1 to 19 is used and an object to be measured is measured at a distance between 4 cm and 2 m inclusive.

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