DE102022101227B3 - Ultrasonic sensor with an object detection of objects in the close range - Google Patents

Abstract

The invention relates to an ultrasonic measuring system 22 for surroundings detection devices, in particular parking aids, of vehicles and/or robots. The ultrasonic measuring system 22 includes an ultrasonic sensor 1. The ultrasonic sensor 1 has a close range in which it can no longer detect the distance from the ultrasonic sensor 1 to objects 11 with emitted ultrasonic bursts 10 of a first temporal length without additional measures. The method uses transmitted ultrasonic bursts 10 of a first temporal length for main ultrasonic measurements 505 if there is no object 11 in the vicinity of the ultrasonic sensor 1, and detects the presence of an object 11 in the vicinity of the ultrasonic sensor 1 if the object 11 is there. The method shortens the first temporal length of the transmitted ultrasonic bursts 10 to a second temporal length of the transmitted ultrasonic bursts 10 and detects a distance between the ultrasonic sensor 1 and the object 11 for the duration of the stay of the object 11 in the vicinity of the ultrasonic sensor 1.

Description

field of invention

The invention is directed to an ultrasonic sensor system with object detection for objects in the close range of an ultrasonic sensor of the ultrasonic sensor system and an associated method for detecting objects in the close range of an ultrasonic sensor at the end of the decay process of the oscillating element of the ultrasonic transducer of the ultrasonic sensor with temperature and parameter compensation.

General introduction

Vehicles need so-called driver assistance systems for autonomous driving. Documents from the prior art also refer to these as ADAS systems (English Advanced Driver Assistance Systems). These ADAS systems require sensor data from sensors. These sensors provide the ADAS system with environmental data about the vehicle's surroundings. An important class of such environment sensors are ultrasonic sensors of ultrasonic sensor systems. Such ultrasonic sensor systems generally include a control unit and a plurality of ultrasonic sensors. The control unit is typically connected to the ultrasonic sensors via one or more data buses. The data buses of older ultrasonic sensors are analog and more or less comprise the output of a comparator within the ultrasonic sensor. More modern ultrasonic sensors include, among other things, their own computer core, which controls the transmission of the ultrasonic burst and the reception of the ultrasonic echo signals, communicates with the control unit and, if necessary, processes and compresses the data.

The following section explains the problem to be solved using the figures of the document presented here.

Typically, an ultrasonic sensor 1 in the sense of the document presented here includes this computer core 2, a digital ultrasonic burst generator, an analog ultrasonic transmitter stage.

The computer core 2 controls the digital ultrasonic burst generator 3 of the ultrasonic sensor 1, preferably by means of a control signal or several control signals 4. Typically, the data connection between the ultrasonic burst generator 3 of the ultrasonic sensor 1 and the computer core 2 has a return channel, with which the computer core 2 can check the status of the ultrasonic burst generator 3 of the Ultrasonic sensor 1 can check.

The digital ultrasonic burst generator 3 generates a digital ultrasonic transmission signal 5 at the request of the computer system 2.

An analog ultrasonic transmission stage 6 typically converts the digital ultrasonic transmission signal 5 into a control signal 7 . The control signal 7 supplies the piezoelectric oscillating element 8 of a connected ultrasonic transducer 9 with pulsed electrical energy in the temporal transmission phase during the generation of an ultrasonic burst 10 to be transmitted. The pulse frequency of the pulsing of the energy supply of the oscillating element 8 is typically close to the resonant frequency of the oscillating element 8 of the ultrasonic transducer 9. As a result, the oscillating element 8 of the ultrasonic transducer 9 oscillates with the pulse frequency in this transmission phase. The oscillating element 8 of the ultrasonic transducer 9 transmits its mechanical vibration to the surrounding air, as a result of which the ultrasonic transducer 9 emits an ultrasonic burst 10 . A transmitted ultrasonic burst 10 preferably comprises a plurality of pulses that follow one another directly at the pulse frequency. A pulse in the sense of the document presented here is a single compression or expansion wave of the air. An ultrasonic burst includes at least one pulse in the sense of the document presented here. An ultrasonic burst within the meaning of the document presented here can comprise a plurality of pulses that follow one another in time. The number of consecutive pulses of a transmitted ultrasonic burst 10 can be small or large. The pulses within a transmitted ultrasound burst 10 follow one another at a pulse interval that corresponds to the respective instantaneous reciprocal of the instantaneous pulse frequency. Accordingly, the transmitted ultrasound bursts 10, which an ultrasound transducer 9 transmits, can be transmitted ultrasound bursts 10 that are longer or shorter in terms of time . An ultrasonic burst 10 that is emitted for a shorter period of time comprises a few pulses. An ultrasonic burst 10 transmitted over a longer period of time comprises a larger number of pulses.

Objects 11 in the area surrounding the vehicle reflect the transmitted ultrasonic bursts 10 as reflected ultrasonic bursts 12.

After the generation of a transmitted ultrasonic burst 10, the ultrasonic sensor 1 goes into a temporal decay phase. In this decay phase, the ultrasonic sensor 1 is generally not able to receive reflected ultrasonic bursts 12 for the duration of a decay time, since the oscillation amplitude of the piezoelectric oscillating element 8 of the ultrasonic sensor 1 is still too high at the beginning of the decay phase. As in the transmission phase, the analog ultrasound continues Transmission stage 6 typically continues to convert the digital ultrasonic transmission signal 5 of the decay phase into a control signal 7 . The drive signal 7 of the decay phase, however, now takes mechanical vibration energy from the piezoelectric vibrating element 8 while the piezoelectric vibrating element 8 is decaying the decay phase so that this internal resistance converts a maximum of energy of the piezoelectric vibrating element 8 into thermal energy. These measures shorten the duration of the decay time of the oscillating element 8 after the end of the transmission phase. Nevertheless, the ultrasonic transducer 9 is not ready to receive during the decay time. In this decay time, however, the transmitted ultrasonic burst 10 already covers a not inconsiderable distance in the free space between the ultrasonic transducer 9 and the object 11 that may be present. Half of the distance covered by the transmitted ultrasonic burst 10 in the decay time is the close range of the ultrasonic sensor 1 in the sense of the document presented here. Objects 11 that are in this close range of ultrasonic sensor 1 cannot therefore be reliably detected by ultrasonic sensor 1 without special measures.

After the end of the decay phase, reflected ultrasonic bursts 12 that arrive then excite the piezoelectric oscillating element 8 of the ultrasonic transducer 9 again to mechanical oscillations. These new mechanical oscillations of the piezoelectric oscillating element 8 in the reception phase lead to an electrical ultrasonic reception signal 13. The piezoelectric oscillating element 8 of the ultrasonic transducer 9 generates the electrical ultrasonic reception signal 13 depending on the received, arriving, reflected ultrasonic burst 12. An amplifier 14 of the ultrasonic sensor 1 detects the electric ultrasound reception signal 13 and converts it into an amplified electric ultrasound reception signal 15 . If necessary, the amplifier 14 filters and amplifies the received electrical ultrasonic signal 13 into the amplified received electrical ultrasonic signal 15. The amplified received electrical ultrasonic signal 15 preferably includes an envelope signal which reflects the amplitude profile of the received electrical ultrasonic signal 13 and which therefore no longer has the pulse frequency. In many preferred applications, the amplified electrical ultrasound reception signal 15 also includes an optional analog phase signal that reproduces the phase shift between the drive signal 7 and the signal component of the ultrasound reception signal 13 that corresponds to the drive signal 7 . The amplifier 14 can thus include a synchronous demodulator, for example, which carries out an I/Q analysis of the received ultrasonic signal 13, for example. The amplified electric ultrasound received signal 15 can therefore also include a plurality of signals in the sense of the document presented here, which the amplifier 14 derives from the ultrasound received signal 13 . In the sense of the document presented here, these signals are not limited to the envelope signal and/or the phase signal. An analog-to-digital converter 16 of the ultrasonic sensor 1 preferably samples these signals of the amplified electrical ultrasonic reception signal 15 at a sampling frequency and converts the amplified electrical ultrasonic reception signal 15 to a digitized ultrasonic reception signal 17. The digitized ultrasonic reception signal 17 can accordingly comprise a plurality of digitized ultrasonic sub-signals. The analog-to-digital converter 16 of the ultrasonic sensor 1 preferably samples a signal of the amplified electrical ultrasonic received signal 15 at the sampling frequency and converts this signal of the amplified electrical ultrasonic received signal 15 to a digitized ultrasonic sub-signal of the digitized ultrasonic received signal 17 associated with this signal. The digital Ultrasonic sub-signals thus together form the digitized ultrasonic received signal 17 . The filtered ultrasound reception signal 19 can also include a number of sub-signals. The digital processing and filter stage 18 and/or the computer core 2 of the ultrasonic sensor 1 preferably compress the filtered received ultrasonic signal 19 to form a compressed received ultrasonic signal. In the simplest case, the compression is a threshold value comparison of the value of the envelope signal with a threshold value. The computer core 2 of the ultrasonic sensor 1 transmits the compressed ultrasonic received signal via a data bus 20 to a control unit 21 of the ultrasonic sensor system 22, which is preferably connected to a plurality of ultrasonic sensors 1 via this data bus 20 and/or via other data buses. The data buses can be, for example, a DSI3 data bus or a PSI5 data bus or the like.

As already mentioned, there is the problem in the prior art of detecting reflected ultrasonic bursts 12 from objects 11 in the vicinity of the ultrasonic sensor 1 when the oscillating element 8 of the ultrasonic transducer 9 has not yet come to rest.

From the state of the art is the writing DE 10 2015 002 269 B3 known. In practical application it has been shown that the procedure of the technical teaching of DE 10 2015 002 269 B3 for detecting reflected ultrasonic bursts 12 from objects 11 in the vicinity of the ultrasonic sensor 1 is parameter and temperature dependent. This method is therefore not yet used in safety-relevant ultrasonic sensors 1 in vehicles.

At the one in Scripture DE 10 2015 002 269 B3 In the method described above, a first comparator 23 compares the electrical ultrasonic reception signal 13 of the piezoelectric oscillating element 8 of the ultrasonic transducer 9 with a first threshold value, for example the value of a first threshold value signal 24, and generates a first comparator output signal 25. The computer core 2 and/or the digital processing and filter stage 18 the first comparator output signal 25 from.

At the one in Scripture DE 10 2015 002 269 B3 In the method described, a second comparator 26 compares the amplified ultrasound reception signal 15 of the amplifier 14 with a second threshold value, for example the value of a second threshold value signal 27, and generates a second comparator output signal 28. The amplifier 14 already generates the said, now analog envelope signal. The second comparator 26 therefore preferably compares the amplitude value of the envelope signal of the amplifier 14 with the second threshold value 105 of the second threshold value signal 27 and thus generates the second comparator output signal 28. The gain of the amplifier 14 is typically in the range from 20 dB to 60 dB. The computer core 2 and/or the digital processing and filter stage 18 preferably evaluate the second comparator output signal 28 or a signal 31 derived therefrom. For this purpose we first assume that the EXOR gate 30 is transparent and that the output signal of the EXOR gate 30 corresponds to the second comparator output signal 28 . The document presented here later describes the function of the EXOR gate 30, so that this simplification, which only serves to improve understanding, then no longer applies. Instead of the EXOR gate 30, the device can also comprise a more complicated logic circuit, which can preferably be functionally equivalent to an EXOR gate at times. The digital conditioning and filtering stage 18 can include the EXOR gate 30 and the output signal 31 of the EXOR gate 30 . The computer core 2 and/or the digital processing and filter stage 18 can optionally emulate the digital processing and filter stage 18 and/or the EXOR gate 30 and the output signal 31 of the EXOR gate 30 .

The procedure of the technical teaching of writing DE 10 2015 002 269 B3 proposes detecting the first time difference 101 between the first time of the first edge change 102 of the first comparator output signal 25 and the subsequent second time of the second edge change 103 of the second comparator output signal 28 . Since the first threshold value of the first threshold value signal 24 is a very high first threshold value based on the evaluation of the unamplified electrical ultrasonic received signal 13 and since the second threshold value 105 of the second threshold value signal 27 is a very low second threshold value 105 based on the evaluation of the amplified ultrasonic received signal 15, the following follows second point in time of the second edge change 103 always follows the first point in time of the first edge change 102 in time. This is due to the fact that the second point in time of the second flank change 103 requires a greater drop in the oscillation amplitude of the piezoelectric oscillating element 8 than the first point in time of the first flank change 102. The method of the technical teaching of the document DE 10 2015 002 269 B3 thus uses the first time difference 101 between two points in time. Each of these two points in time indicates that the amplitude of the envelope curve signal has fallen below two respective, corresponding and very different threshold values during the decay process. On the one hand, the method uses the first comparator 23, the comparison input of which is preferably connected directly to the oscillating element 8 (high first threshold value) via the electrical ultrasound reception signal 13. On the other hand, the method uses the comparison input of the second comparator 26 to evaluate the envelope signal (low threshold value) generated after the amplification (40-60 dB) of the amplified electrical ultrasonic reception signal 15. This first time difference 101 has proved to be very temperature-dependent in tests when the proposal was being worked out exposed and unfortunately prevented the commercial application so far.

However, a near-field measurement in automotive ultrasonic sensor systems is a requirement that should definitely be met. However, as described above, that is in Scripture DE 10 2015 002 269 B3 described close-range method based on the temperature-dependent first time difference 101 parameter and temperature-dependent. The previously realized microelectronic circuits support the process of DE 10 2015 002 269 B3 therefore not.

From the DE 10 2018 109 318 A1 a method for operating an ultrasonic sensor device for a motor vehicle is known, in which, in a first operating mode, an ultrasonic sensor of the ultrasonic sensor device is used continuously measurements are carried out. In a measurement with the at least one ultrasonic sensor is according to the technical teaching of DE 10 2018 109 318 A1 an ultrasonic signal is emitted and the ultrasonic signal reflected in an area surrounding the motor vehicle is received. According to the technical teachings of DE 10 2018 109 318 A1 Both coded measurements, in which the ultrasonic signal is transmitted in coded form, and uncoded measurements, in which the ultrasonic signal is transmitted in uncoded form, are carried out in the first operating mode. In this case, according to the technical teaching of DE 10 2018 109 318 A1 changing from the first operating mode to a second operating mode if it is detected that an object is located in a predetermined close range in the area, wherein only uncoded measurements are carried out with the at least one ultrasonic sensor in the second operating mode.

Task

The object of the proposal is therefore to create a solution that does not have the above disadvantages of the prior art and has other advantages. The aim is to provide a solution for reducing or avoiding the temperature and parameter dependency of the method DE 10 2015 002 269 B3 .

This object is solved by the technical teaching of independent claim 1. Further refinements may be the subject of dependent claims.

solution of the task

According to the proposal, an ultrasonic sensor system 22 of the type described at the beginning solves the problem in that the ultrasonic sensor 1 carries out an additional compensation measurement according to the proposal, in contrast to the prior art. Applications of the proposed method for operating an ultrasonic measurement system 22 can be found in particular in surroundings detection devices. For example, vehicles and/or robots and/or other mobile devices can use such environment detection devices. These environment detection devices can be parking aids and/or collision prevention devices, for example. In the case of robots, the environment detection devices can also be used to generate a virtual environment map in a computer system of the robot. For example, such an environment detection device can be used to identify and classify obstacles of all kinds. Mobile devices within the meaning of the document presented here can be, in particular but not limited to, devices such as electric transport carts, forklifts, delivery robots, transport robots, but also missiles such as helicopters and/or drones.

Stationary devices can use the surroundings detection devices presented here for the measurement of objects that are closer to the surroundings detection device or pass the surroundings detection device inside or outside the relevant stationary devices or move away from the surroundings detection device. For example, a parcel sorting system can use an environment detection device presented here in order to measure and possibly classify mail items, ie parcels, on a conveyor belt of the parcel sorting system. Use in security checkpoints is also conceivable.

The ultrasonic sensor 1 generates a reference measured value or a plurality of reference measured values by means of one or more additional compensation measurements 504 with a transmitted ultrasonic burst 10 with only one pulse. The computer core 2 of the ultrasonic sensor 1 and/or the control unit 21 of the ultrasonic sensor system 22, for example, offset this generated reference measured value or these generated reference measured values against the measured value of a temporally subsequent main ultrasonic measurement 505 of the ultrasonic sensor 1. For better understanding, the document presented here refers to this in this context 5 . If the control unit 21 of the ultrasonic sensor system 22 carries out the calculation, the computer core 2 of the ultrasonic sensor 1 first transmits the reference measured value or the reference measured values to the control unit 21 of the ultrasonic sensor system 22. The computer core 2 and/or the control unit 21 thus generate a respective compensation value from the reference measured value or from the several reference measured values. If necessary, the computer core 2 and/or the control device 21 can generate a common reference measured value from a plurality of reference measured values.

The following text represents the proposed measurement sequence that the proposed ultrasonic sensor system 22 and its ultrasonic sensor 1 execute.

In a first step, the ultrasonic sensor 1 of the ultrasonic sensor system 22 carries out a first compensation measurement 504 with a short emitted ultrasonic burst 10 . The short transmitted ultrasonic burst 10 preferably comprises only a few pulses. The short transmitted ultrasonic burst 10 preferably comprises only 5, better 4, better 3, better 2, better 1 pulse. In this case, a transmitted ultrasonic burst 10 has exactly one pulse particularly preferred for the compensation measurement 504. This also has the advantage, among other things, that the close range for the temporally short ultrasonic burst of the compensation measurement 504 is particularly small.

In a second, preferably subsequent step, the ultrasonic sensor 1 carries out a second main ultrasonic measurement 505 with an ultrasonic burst 10 emitted over a long period of time. The long ultrasonic burst 10 emitted preferably comprises only more pulses than the short ultrasonic burst 10 emitted. A long transmitted ultrasonic burst 10 with more than 5 pulses is particularly preferred.

The method disclosed here proposes sending out a first short ultrasonic burst 10 for a compensation measurement 504 . The ultrasonic transducer 9 of the ultrasonic sensor system 22 then receives the short reflected ultrasonic burst 12 and converts it back into the electric ultrasonic received signal 13 . The ultrasonic sensor system 22 receives a first short reflected ultrasonic burst 12, which is expressed in the amplitude curve 107 of the envelope signal of the amplified electric ultrasonic received signal 15 as the first ultrasonic envelope signal 504. As in the case of the technical teaching of DE 10 2015 002 269 B3 the ultrasonic sensor system 22 uses the amplitude profile 107 of the envelope signal of the amplified electrical ultrasonic received signal 15 of the first ultrasonic envelope signal 504 to determine a first time difference 101 between the first point in time of the first edge change 102 of the first comparator output signal 25 and the subsequent second point in time of the second edge change 103 of the second comparator output signal 28 The first threshold value of the first threshold value signal 24 is a very high first threshold value due to the evaluation of the unamplified electrical ultrasound reception signal 13 . The second threshold value 105 of the second threshold value signal 27 is a very low second threshold value 105 due to the evaluation of the amplified ultrasonic received signal 15. Therefore, the second point in time of the second edge change 103 always follows the first point in time of the first edge change 102, also here in the case of the first ultrasonic envelope signal 504 . This is due in particular to the fact that the second point in time of the second edge change 103 requires a greater drop in the oscillation amplitude of the piezoelectric oscillating element 8 than the first point in time of the first edge change 102.

The method disclosed here proposes that after the compensation measurement 504 with the transmission of a first short ultrasound burst 10 the ultrasound system 22 carry out an ultrasound main measurement 505 with the transmission of a second, long ultrasound burst 10 . The ultrasonic transducer 9 of the ultrasonic sensor system 22 then receives the long reflected ultrasonic burst 12 and converts it back into the electric ultrasonic received signal 13 . The ultrasonic sensor system 22 receives this second, long, reflected ultrasonic sensor burst 12. The second, long, reflected ultrasonic sensor burst 12 is expressed in the amplitude profile 107 of the envelope signal of the amplified electric ultrasonic received signal 15 as a second ultrasonic envelope signal 505. As in the case of the technical teaching of DE 10 2015 002 269 B3 the ultrasonic sensor system 22 now determines a second time difference 501 from the amplitude profile 107 of the envelope signal of the amplified electrical ultrasonic reception signal 15 of the second ultrasonic envelope signal 505. This is the second time difference 501 between the third point in time 502 of the third edge change 502 of the first comparator output signal 25 and the subsequent fourth point in time 503 of the fourth edge change 503 of the second comparator output signal 28. Again, the first threshold value of the first threshold value signal 24 is a very high first threshold value due to the evaluation of the unamplified electrical ultrasound reception signal 13. Likewise, the second threshold value 105 of the second threshold value signal 27 is again a very low second threshold value 105 due to the evaluation of the amplified ultrasonic received signal 15. Therefore, the fourth point in time of the fourth edge change 503 always follows the third point in time 502 of the third edge change 502, also here in the case of the second ultrasonic envelope signal 505 time after. This is also due to the fact that the fourth point in time of the fourth edge change 503 requires a greater drop in the oscillation amplitude of the piezoelectric oscillating element 8 than the third point in time 502 of the third edge change 502.

The elaboration of the technical teaching of the document presented here surprisingly showed that the course of the temperature dependency of the first time difference 101 and the second time difference 501 run essentially parallel. For this purpose, the text presented here refers to the example, schematically sketched 6 , which is the result of laboratory measurements.

First of all, the description presented here focuses on an embodiment in which an envelope filter is part of an analog input amplifier 14 . This expression is in 1 shown schematically and in a simplified manner.

• • eine Differenz 601 aus erster Zeitdifferenz 101 minus der zweiten Zeitdifferenz 501 und/oder
• • eine Differenz 601 aus zweiter Zeitdifferenz 501 minus der ersten Zeitdifferenz 101 und/oder
• • das Verhältnis von zweiter Zeitdifferenz 501 geteilt durch die erste Zeitdifferenz 101 und/oder
• • das Verhältnis von erster Zeitdifferenz 101 geteilt durch die zweite Zeitdifferenz 501 und/oder
• • eine Verknüpfung der Werte der ersten Zeitdifferenz 101 und der zweiten Zeitdifferenz 501 mit funktionsäquivalenter Wirkung zu den drei vorausgehenden Vergleichsmetoden für den Vergleich der Werte der ersten Zeitdifferenz 101 mit denen der zweiten Zeitdifferenz 501

zu benutzen. Bevorzugt verwenden der Rechnerkern 2 und/oder die digitale Aufbereitungs- und Filterstufe 18 diese Vergleichsmethode. Bevorzugt erfassen hierzu der Rechnerkern 2 und/oder die digitale Aufbereitungs- und Filterstufe 18 die erste Zeitdifferenz 101 und/oder die zweite Zeitdifferenz 501.The core of the method proposed here is now the method of DE 10 2015 002 269 B3 to use, but as input value the DE 10 2015 002 269 B3 not to use the first time difference 101 or the second time difference 501, but

• • a difference 601 from the first time difference 101 minus the second time difference 501 and/or
• • a difference 601 from the second time difference 501 minus the first time difference 101 and/or
• • the ratio of the second time difference 501 divided by the first time difference 101 and/or
• • the ratio of the first time difference 101 divided by the second time difference 501 and/or
• • a combination of the values of the first time difference 101 and the second time difference 501 with a functionally equivalent effect to the three previous comparison methods for comparing the values of the first time difference 101 with those of the second time difference 501

to use. The computer core 2 and/or the digital processing and filter stage 18 preferably use this comparison method. For this purpose, the computer core 2 and/or the digital processing and filter stage 18 preferably record the first time difference 101 and/or the second time difference 501.

The technical teaching presented here provides the said first comparator 23 in a more analogue form, which is preferably connected directly to the electric ultrasonic received signal 13 of the oscillating element 8 of the ultrasonic transducer 9 . Said first comparator 23 preferably compares the output voltages of the ultrasonic transducer 9 of the electrical ultrasonic reception signal 13 directly with a fixed first threshold value of a first threshold value signal 24. The first comparator output signal 25 of this first comparator 23 is in 1 shown as an example. The first comparator 23 can also be implemented in a digital part in its effect on the signal evaluation. The computer core 2 can also emulate the first comparator 23, if necessary, as a comparison operation. In the last two cases, it is expedient if the position of the analog-to-digital converter 16 is positioned correspondingly earlier in the signal path. The document disclosed here refers to this by way of example 4 . In the following, the document presented here describes an example of an implementation using an analog first comparator 23 without restricting the technical teaching of the disclosure presented here to the implementation of the comparison using an analog circuit as the first comparator 23 .

The first comparator output signal 25 of this exemplary first comparator 23 typically shows a digital oscillation as long as the amplitude of the electric ultrasonic received signal 13 of the ultrasonic transducer 9 still has a significant level. Typically, the fixed first threshold value, which the exemplary first comparator 23 of the ultrasonic sensor system 22 uses for the comparison with the transducer voltage amplitude of the electrical ultrasonic received signal 13 of the ultrasonic transducer 8, has such a value that the first point in time 102 or the third Point in time 502 of the end of this oscillation within a transmission period does not shift or only shifts by a few oscillation cycles, even with a very close object in the vicinity of ultrasonic sensor 1, for example when the temperature of ultrasonic sensor system 22 changes. In this way, for example, the digital processing and filter stage 18 or the computer core 2 can, by digitally smoothing and filtering the first comparator output signal 25 of this first comparator 23, determine the end of the decay time at a first point in time 102 of the first edge change 102 of the first comparator output signal 25 or at a third Safely detect the time 502 of the third edge change 502 of the first comparator output signal 25 within a transmission period. A transmission period within the meaning of the document presented here begins with the beginning of the first pulse of a first ultrasonic burst and ends with the beginning of the first pulse of the ultrasonic burst immediately following in time. This first point in time 102 of the first edge change 102 of the first comparator output signal 25 is typically a first temperature-dependent time difference 101 before the second point in time 103 at which the envelope signal of the amplified electrical ultrasonic reception signal 15 falls below the second threshold value of the second threshold value signal 27. However, due to the large amplitude, this second point in time 103 is practically independent of repercussions from sound reflections on the ultrasonic transducer 9. The third point in time 502 of the third edge change 502 of the first comparator output signal 25 is also a temperature-dependent, second time difference 501 before the fourth point in time 503 falling below the second threshold value of the second threshold value signal 27 by the envelope signal of the amplified electrical ultrasound reception signal 15, but is practically independent of repercussions due to sound reflections on the ultrasound transducer 9 due to the large amplitude.

The digital processing and filter stage 18 or the computer core 2 can now preferably be based, for example, on this first point in time 102 of the first edge change 102 of the first comparator output signal 25 or based on this third point in time 502 of the third edge change 502 of the first comparator output signal 25 only after the elapse of a respective subsequent third time difference by a timer 41 that the second comparator output signal 28 of the second comparator 26 signals the reception of an echo after evaluation of the amplified electrical ultrasonic reception signal 15. The timer 41 is preferably part of the digital processing and filter stage 18. The digital processing and filter stage 18 typically controls the timer 41 as a function of the output signal 31 of the EXOR gate 30 or of the output signal of an EXOR gate 30 that is functionally equivalent third logic circuit. Furthermore, the digital processing and filter stage 18 typically controls the timer 41 as a function of the first comparator output signal 25 4 Control and / or influence drawn signal lines. Alternatively, the computer core 2 can implement the function of the timer 41, for example by emulation, and influence the envelope filter 33 by means of a signal line. The second comparator 26 preferably starts the timer 41 when the first point in time 102 or when the third point in time 502 is reached by means of a signaling which can run via the digital processing and filter stage 18, for example.

The first comparator output signal 25 of the first comparator 23 signals the beginning of the decay process of the ultrasonic transducer 9 by the first edge change 102 at the first time 102 or by the third edge change 502 at the third time 502. The second comparator output signal 28 of the second comparator 26 signals the end of the decay process of the ultrasonic transducer 9 by the second edge change 103 at the second point in time 103 or by the fourth edge change 503 at the fourth point in time 503. A small modification can bring about a corrected display of a reflection by the second comparator output signal 28 of the second comparator 26. An EXOR gate 30 or a temporarily functionally equivalent logic can, for example, signal the end of the decay process of the oscillating element 8 of the ultrasonic transducer 9 . The second comparator output signal 28 of the second comparator 26 and preferably an EXOR control signal 32 of the digital processing and filter stage 18 or the computer core 2 form the preferred inputs of the EXOR gate 30 or said logic. The output 31 of the EXOR gate 30 preferably forms an input signal for the digital processing and filter stage 18.

For this purpose, the EXOR gate 30 or the said logic switch the second comparator output signal 28 of the second comparator 26 to a first logic level. This preferably takes place at the end of the transmission phase of the ultrasonic transducer 9 for a predefined third time period based on the first point in time 102 or third point in time 502. The first comparator output signal 25 of the first comparator 26 signaled the end of the transmission phase of the ultrasonic transducer 9. The first comparator 23 detected the first point in time 102 or the third point in time 502 of the decay of the ultrasonic transducer 9. The length of this third time period preferably corresponds to the length of the first time difference 101 without a reflecting object. The ultrasound system 22 determines the duration of the first time difference 101, preferably by means of a short ultrasound pulse in the said exemplary compensation measurement 504. This is in 2 and 5 shown. The length of the third time period is preferably not based on the length of the second time difference 501. That is, the document presented here proposes defining the length of the third time period as a function of a detected first time difference 101, which the ultrasonic sensor system 22 detects with a short ultrasonic burst 504 in an exemplary compensation measurement 504.determined.

If an object 11 is now spatially close to the ultrasonic transducer 9, the early-arriving echo of the early-arriving, reflected ultrasonic burst 12 raises the amplitude curve 107 of the envelope curve in the corresponding time range. However, the fourth point in time 503 is now shifted back in time. Since the short ultrasonic pulse of the compensation measurement 504 has a smaller near range, there is a range in which the second point in time 103 has not yet shifted back in time. Due to the EXOR operation of the EXOR gate 30 or with a suitable design of the corresponding alternative logic, the output of the EXOR circuit 30 switches the first comparator output signal 25 of the first comparator 23, which was previously present at the output 31 of the EXOR gate 30, to the inverted logical value, which corresponds to an echo. The surprising finding disclosed here is that, firstly, the ultrasonic sensor system 22, in contrast to the prior art, is able to detect an object 11 in the close range of the ultrasonic sensor system 22, but without being able to determine the exact location of this object 11 . By using the value of the first time difference 101 as the loading value of the counter of the timer 41, however, this recognition is no longer temperature-dependent and therefore usable. If the counter value of the time counter of the timer 41 reaches this loading value, the timer 41 actuates the EXOR control signal 32 of the EXOR gate or of the third logic circuit 30. As a result, the digital processing and filter stage 18 detects the presence of an object 11 in the vicinity. With this proposed method, an exact determination of the position of the object 11 in the close range is not possible. However, it is completely sufficient for most applications if the presence of an object 11 can already be detected in this close range. These measures up to this point already improve the reception behavior of the ultrasonic sensor system 22 in the close range.

However, it has also been shown that the digital processing and filter stage 18 or the computer core 2 should carry out an optimized adaptation of the filtering of the envelope signal of the amplified electrical ultrasonic reception signal 15 and the comparator output signals 28, 25 in parallel with the above measures in order to actually area to achieve useful results. Both measures, the one described immediately above and the one described below, result in an improvement on their own. Experience has shown that these two measures are typically not sufficient on their own for automotive applications.

The following section deals with the parameterization of the envelope filter, in particular for the time of the main ultrasound measurement 505. In contrast to the prior art, one or more parameters of the envelope filter depend on the first point in time 102 and/or the second point in time 103 and/or the value of the first time difference 101, which the ultrasonic sensor system 22 preferably determines by means of a compensation measurement 504 that preferably immediately precedes it.

The document presented here therefore also proposes that the ultrasonic sensor system 22 uses a method for adapting the parameters of the envelope filter in the amplifier 14 for filtering the envelope signal of the amplified electric ultrasonic received signal 15 . For the purposes of the document presented here, the amplifier 14 can comprise an envelope filter with a bandpass characteristic. The proposed method again determines the second point in time 103 at which the instantaneous value of the magnitude of the envelope signal of the amplified electric ultrasonic received signal 15 falls below the second threshold value 105 of the second threshold value signal 27 . The document presented here now proposes that from this specific second point in time 103, for example, the computer core 2 or the digital processing and filter stage 18 switch the bandpass characteristic of the envelope filter of the amplifier 14 in such a way that the bandpass characteristic of the envelope filter of the amplifier 14 becomes narrower. The instantaneous value of the envelope signal of the amplified electrical ultrasonic received signal 15 falling below the second threshold value 105 of the second threshold value signal 27 occurs at said second point in time 103 during the compensation measurement 504 or at a fourth point in time 503 during the main ultrasound measurement 505. The bandpass characteristic of the envelope filter of the amplifier 14 is therefore preferably narrower in a certain time period immediately before this switchover at this second point in time 103 or at this fourth point in time 503 . At the end of an ultrasonic pulse period, the digital processing and filter stage 18 and/or the computer core 2 therefore preferably set the relevant parameters of the envelope filter and/or the amplifier 14 and/or the other device parts of the ultrasonic sensor system 22 or the ultrasonic sensor 1 for the beginning an ultrasonic pulse period provided start values back again. This typically does not apply to the detected length of the first time difference 101, which is preferably retained until the next measurement of the duration of this first time difference 101 by means of a short ultrasonic pulse in a compensation measurement 504. As a result, the value of the envelope signal of the amplified electrical ultrasonic received signal 15 falls with a slower edge. With such a second threshold value signal 27, a nearby object 11 with a so-called “near echo” arriving shortly after the emission of the ultrasonic burst no longer causes the envelope signal of the amplified electric ultrasonic received signal 15 to fall below the second threshold value 105. The ultrasonic sensor system 22 can then no longer determine the fourth point in time 503 . The digital processing and filter stage 18 and/or the computer core 2 and/or the ultrasonic sensor system 22 and/or the ultrasonic sensor then preferably use the value of the transmission period as a substitute value, which corresponds to the interval between two pulses. They then preferably use this value as a substitute value for the second time difference 501. A nearby object 11 with a so-called “very close echo” arriving shortly after the ultrasonic burst was emitted can also cause the second threshold value 105 to fall below the second Threshold signal 27 lead at a first point in time 102 through the envelope signal of the amplified electric ultrasound reception signal 15 . The reason is that the oscillation of the ultrasonic transducer 9 has not yet ended and the object 11 is then so close that the short ultrasonic burst of the compensation measurement 504 is also disrupted.

• • Der Zeitwert des Zeitraums der vergangenen Zeit kann dabei die Dauer des Zeitraums sein, der mit dem Ausschalten der Treiberstufen für den Ultraschall-Transducer 9 am Ende der Sendephase zu einem zweiten Zeitpunkt 103 bzw. zu einem vierten Zeitpunkt 503 beginnt. Die digitale Aufbereitungs- und Filterstufe 18 oder der Rechnerkern 2 führen bevorzugt das Umschalten und/oder das Nachregeln von Parametern des Hüllkurvenfilters in Abhängigkeit von der Zeit ab dem zweiten Zeitpunkt 103 bzw. ab dem vierten Zeitpunkt 503 durch.
• • Alternativ oder auch zeitlich parallel können die digitale Aufbereitungs- und Filterstufe 18 oder der Rechnerkern 2 das Umschalten und/oder das Nachregeln von Parametern des Hüllkurvenfilters in Abhängigkeit von der Zeit ab dem bereits besprochenen ersten Zeitpunkt 102 bzw. ab dem dritten Zeitpunkt 503, ab dem das erste Komparatorausgangssignal 25 des ersten Komparators 23 keine Oszillationen mehr zeigt, durchführen.
• • Alternativ oder auch zeitlich parallel können die digitale Aufbereitungs- und Filterstufe 18 oder der Rechnerkern 2 auch das Umschalten und/oder das Nachregeln von Parametern des Hüllkurvenfilters in Abhängigkeit von dem Hüllkurvensignal des verstärkten elektrisches Ultraschallempfangssignals 15 durchführen.

The paper presented here proposes that the digital conditioning and filtering stage 18 or the processor core 2 switches the envelope filter in steps during a transmission period. The envelope filter is preferably an envelope filter of the amplifier 14. In extreme cases, this switching can be done in such a way that the digital processing and filter stage 18 or the computer core 2 continuously transmits analog components of the envelope filter that determine the characteristic frequency by means of signaling to the amplifier 14 via signals not shown in the figures Adjust control lines. The digital processing and filter stage 18 or the computer core 2 switch over or readjust the envelope filter, typically a bandpass filter, preferably as a function of the time that has elapsed since the first point in time 102 . Typically, the switching or readjustment relates to the characteristic frequencies and/or amplitudes of the transfer function of the envelope filter. Various ways of defining the time value of the period of time elapsed are possible

• The time value of the period of time that has passed can be the duration of the period that begins when the driver stages for the ultrasonic transducer 9 are switched off at the end of the transmission phase at a second point in time 103 or at a fourth point in time 503 . The digital processing and filter stage 18 or the computer core 2 preferably performs the switching and/or the readjustment of parameters of the envelope filter depending on the time from the second point in time 103 or from the fourth point in time 503.
• Alternatively or at the same time, the digital processing and filter stage 18 or the computer core 2 can switch over and/or readjust parameters of the envelope filter depending on the time from the already discussed first point in time 102 or from the third point in time 503 which the first comparator output signal 25 of the first comparator 23 no longer shows any oscillations.
• Alternatively or at the same time, the digital processing and filter stage 18 or the computer core 2 can also switch and/or readjust parameters of the envelope filter as a function of the envelope signal of the amplified electric ultrasonic received signal 15 .

In the latter case, a step-by-step switchover may require further comparators or devices that are functionally equivalent to these comparators and that carry out these switchovers as a function of corresponding further switching thresholds with corresponding further switching threshold signals.

A threshold-value generating device 29 preferably generates the threshold-value signals 24 and 27 and possibly further threshold-value signals. The digital processing and filter stage 18 and/or the computer core 2 preferably control the threshold value generation device 29 and the generation of the threshold value signals 24 and 27 and the generation of any further threshold value signals by the threshold value generation device 29. The threshold value generation device 29 preferably generates the threshold value signals 24 and 27 and, if necessary the further threshold value signals depending on the time since the first point in time 102 or the time since the third point in time 502 and/or on the time since the second point in time 103 or the time since the fourth point in time 503 and/or depending on the first time difference 101.

As a result, a faster falling edge of the amplitude curve 107 of the envelope signal of the amplified electric ultrasonic reception signal 15 is obtained, whereby the ultrasonic sensor system 22 is sooner able to detect a reflection of objects 11 in the close range.

Adapted to this system-typical envelope curve of the amplitude curve 107 of the envelope signal of the amplified electric ultrasonic received signal 15, an exponentially falling second threshold value signal 27 can now additionally be specified. In this case, the second comparator 26 again detects, for example, that the amplitude curve 107 of the envelope signal of the amplified electrical ultrasonic received signal 15 falls below the second threshold value signal 27. This occurs at the second point in time 103 or the fourth point in time 503. Time-delayed by a third period compared to the said first point in time 102 Within the transmission period, the exponential drop in the value of the second threshold value signal 27 then begins to a predetermined or otherwise determined residual threshold value with a predetermined or determined first time constant τ ₁ . The duration of the third time period preferably depends on the duration of the first time difference 101 or the difference 601 from the second time difference 501 and the first time difference 101 .

The basic method is therefore on the one hand a method for evaluating the electric ultrasonic received signal 13 of a piezoelectric ultrasonic transducer 9. A first comparator 23 or a functionally equivalent device compares the instantaneous value of the electric ultrasonic received signal in a first step 13 of the ultrasonic transducer 9 or a signal derived therefrom with a first threshold value and forms a first comparator output signal 25 or the like depending on the result. In a second step of the basic method, the amplifier 14 forms the amplified electrical ultrasonic received signal 15, which preferably includes an envelope signal, preferably by amplifying and filtering the electrical ultrasonic received signal 13. The amplifier 14 preferably includes an envelope filter which is preferably inserted in the signal formation path of the amplifier 14 for forming the envelope signal. The parameters of the filtering in the envelope filter of the amplifier 14 are preferably designed to be switchable or controllable. In a next step of the basic method, a threshold-value generation device 29 forms the first threshold-value signal 24 and the second threshold-value signal 27 and possibly further threshold-value signals. In particular, the threshold value generation device 29 can generate this and other threshold value signals 24 and 27 from the envelope signal of the amplified electric ultrasonic received signal 15 by filtering. The threshold value generation device 29 can also generate this and other threshold value signals 24 and 27 by filtering from the electric ultrasonic received signal 13 of the ultrasonic transducer 9 . Typically, the second threshold value signal 27 is in comparison to the first threshold value signal 24 such that the first comparator 23 switches at higher amplitudes of the electrical ultrasonic reception signal 13 than the second comparator 26. The second comparator 26 then compares the amplitude profile 107 of the envelope signal with the second threshold value 105 of the second threshold signal 27. The output signal 28 of the second comparator 26 represents the detected echoes. In the close range, the output signal 31 of the EXOR gate 30 reproduces the detected echoes, with the signaling in the close range only saying that an object is in the close range. Therefore, the computer core 2 can optionally signal the output signal 28 of the second comparator 26 or the output signal 31 of the EXOR gate 30 directly to the control device 21 . According to the invention, the determination of the first point in time 102 or the third point in time 502 of the decay of the ultrasonic transducer 9 is of particular importance the activation of the ultrasonic transducer 9 no longer shows a signal. This event at the first point in time 102 or the third point in time 502 typically starts said timer 41 via the digital processing and filter stage 18. The computer core 2 and/or the digital processing and filter stage 18 stop the timer 41 at the end of a transmission period and set it the timer 41 then preferably to a predefined one

value back. The timer 41 can be part of the digital processing and filter stage 18 and/or the computer core 2 . The computer core 2 can emulate the timer 41 . In the example of 1 the timer 41 is, for example, not part of the digital processing and filter stage 18.

This timer 41 switches the second output signal 28 of the second comparator 26 for a predetermined first time period Δt1 after the first point in time 102 or after the third point in time 503 of the decay of the ultrasonic transducer (TR) to the respective other logical value according to the example. So for example from 1 to 0 and vice versa depending on the system design.

This method according to the invention described above corresponds to a device according to the invention in the form of an ultrasonic sensor system 22, which carries out the corresponding method at least in part. The device according to the invention is used to detect the presence of objects in the close range of an ultrasonic measuring system according to the invention, in particular in an automobile. It has an ultrasonic transducer 9 whose voltage signal is recorded. An envelope generation device, which is part of the amplifier 14 of the ultrasonic sensor 1 of the device, determines the said envelope signal of the amplified electrical ultrasonic received signal 15 from the electrical ultrasonic received signal 13 of the ultrasonic transducer 9. A threshold value generator 29, which is also part of the device, also generates a second threshold value signal 27 a second threshold value 105. The device also has said second comparator 26, which compares the second threshold value 105 of the second threshold value signal 24 with the amplitude curve 107 of the envelope signal of the amplified electrical ultrasonic received signal 15. As a result of this comparison, the second comparator generates a second comparator output signal 28 of the second comparator 26. Typically, the second comparator output signal 28 of the second comparator 26 is inverted by logic - for example an EXOR gate 30 - by means of a control signal or to a fixed value, in particular according to the example to logical 1. In addition, the device typically has a first comparator 23, which compares the value profile of the electrical ultrasonic received signal 13 ultrasonic transducer 9 with a first threshold value of a first threshold value signal 24, this first threshold value of the first threshold value signal 24 compared to the second threshold value 105 of the second threshold value signal 27 so is selected so that the first comparator 23 switches at higher values of the electrical ultrasonic reception signal 13 of the ultrasonic transducer 9 than the second comparator 26. As already described above, the device has a point in time determining device that detects the first point in time 102 or the third point in time 502 after the The end of the active activation of the ultrasonic transducer 9 is determined, from which point the values of the electrical ultrasonic received signal 13 of the ultrasonic transducer 9 are no longer sufficient to switch the first comparator 23 over.

This point in time determination device uses a start signal to start a timer 41, which is part of the device, which uses the control signal to set the second comparator output signal 28 of the second comparator 26 to a state for a first time period (Δt1) from the determined first point in time 102 or the third point in time 502 switches in the manner corresponding to the logical value as if there were no reflection. A logic 30 or a functionally equivalent device is preferably used as the switching device. The computer core 2 and/or the digital processing and filter stage 18 preferably control this switchover by means of control signaling 32. The logic can include an EXOR gate 30. In that case, an EXOR control signal 32 can then transfer the signaling to the EXOR gate 30 .

In addition, a proposed device preferably has a further feature which alone already leads to an improvement over the prior art, but which alone does not yet meet the modern requirements of the automotive market. Such a device for detecting the presence of objects in the close range of an ultrasonic measuring system again has an ultrasonic transducer 9 whose electric ultrasonic reception signal 13 is recorded. The device preferably has an envelope generation device as part of an amplifier 14 which determines an envelope signal of an amplified electrical ultrasonic received signal 15 from the electrical ultrasonic received signal 13 of the ultrasonic transducer 9 . In this case, this envelope generator device preferably includes a controllable envelope filter. The proposed device again has a threshold value generator 29, which generates a second threshold value signal 27 with a second threshold value 105, and a second comparator 26, which compares the second threshold value signal 27 with the amplitude profile 107 of the envelope signal of the amplified electric ultrasonic received signal 15 and a second comparator output signal 28 of the second comparator 26 is generated. The computer core 2 and/or the digital processing and filter stage 18 change at least one characteristic frequency of the controllable envelope filter of the amplifier 14 during the operation of the device at least at one point in time as a function of the second comparator output signal 28 of the second comparator 26 or correlated to this second comparator output signal 28 of the second comparator 26.

In a further embodiment, the device also has a first comparator 23, which compares the electrical ultrasonic reception signal 13 of the ultrasonic transducer 9 with a first threshold value of a first threshold value signal 24, this first threshold value of the first threshold value signal 24 compared to the second threshold value 105 of the second threshold value signal 27 is preferably again selected such that the first comparator 23 switches at higher values of the electrical ultrasonic reception signal 13 of the ultrasonic transducer 9 than the second comparator 26. To control the timing, the device again preferably has the said point in time determination device. This determines the first point in time 102 or the third point in time 502 after the end of the active activation of the ultrasonic transducer 9 from which the value of the electrical ultrasonic received signal 13 of the ultrasonic transducer 9 is no longer sufficient to switch over the first comparator 23 . In this way, a fixed time reference point is created, which now enables control tasks. Depending on the elapsed time in relation to this first point in time 102 or this third point in time 502, control tasks for the envelope filter of the amplifier 14 and the threshold value generation 29 can now be carried out as a function of time. The device typically has a timer 41 for this purpose. The timer 41 can be part of the digital processing and filter stage 18, which after at least a third time period (Δt3) and after at least a fourth time period (Δt4) based on the said first point in time 102 or the third point in time 502, the filter characteristic of the envelope filter of the Envelope generator in the amplifier 14 preferably changes at least twice. It is of course conceivable to make this change at many points in time, resulting in a quasi-continuous change in second threshold value signal 27 and/or the parameters of the envelope filter from said first point in time 102 or third point in time 502 . In the extreme case, the timer 41 can be an analog device that generates an analog signal that represents the elapsed period of time linearly or nonlinearly but strictly monotonically decreasing or strictly monotonically increasing through a level, for example, and the second threshold value signal 24 and/or a or continuously controls several of the parameters of the envelope filter.

In the case of discrete control, for example by a digital timer 41, this can also control threshold value generation 29 after at least a fifth time period (Δt5) in relation to said first point in time 102 or third point in time 502 in such a way that second threshold value 105 of the second threshold value signal from this first point in time 102 or from this third point in time 502 falls exponentially with a first time constant τ ₁ to a residual threshold value.

The analog ultrasonic transmission stage 6 of the ultrasonic sensor 1 controls the ultrasonic transducer 9 with the control signal 7 typically at the beginning of a transmission period for the duration of a transmission phase. After the transmission phase, the analog ultrasonic transmitter stage 6 controls the ultrasonic transducer 9 for the duration of a braking phase in such a way that it loses as much energy as possible in a short time in order to decay as quickly as possible. After the end of the braking phase, the ultrasonic transducer 9 continues to oscillate for the duration of a decay phase. The analog ultrasonic transmitter stage 6 is preferably inactive after the oscillation of the ultrasonic transducer 9 in the oscillation decay phase for the remainder of the transmission period in a reception phase. The remainder of the transmission period after the transmission phase and braking phase is divided into decay time and reception time. The transmission periods are typically repeated periodically. A first comparator 23 compares the value of the electrical ultrasonic received signal 13 of the ultrasonic transducer 9 with a first threshold value of the first threshold signal 24, which is typically specified by a threshold generator 29. The first threshold value is selected in such a way that its effect is above the second threshold value 105 of the second threshold value signal 27 . The first comparator output signal 25 of the first comparator 23 is preferably evaluated by a point in time determination device. The time determination device is preferably part of the digital processing and filter stage 18. The computer core 2 can also function as a time determination device. This point in time determination device determines the first point in time 102 or the third point in time 502 after the end of the active control of the ultrasonic transducer 9, after which the value of the electric ultrasonic received signal 13 of the ultrasonic transducer 9 is no longer sufficient to switch the first comparator 23 over. Typically, this first point in time 102 and this third point in time 502 are each in the form of a suitable respective signal at the output of the point in time determination device. This signal typically starts the timer 41. The timer 41 may be part of the digital conditioning and filtering stage 18. The computer core 2 can also work as a timer 41 or include such a timer 41 . Reaching the first point in time 102 or the third point in time 502 within a transmission period preferably starts the timer 41. The end of a transmission period or the beginning of a transmission period preferably resets the timer 41. The timer 41 typically starts when the analog ultrasonic transmission stage 6 of the ultrasonic sensor 1 is switched off. In a first embodiment, the timer 41 switches for a first time period (Δt1) by means of the logic control signal 32 from the first point in time 102 or third point in time 502 in the relevant transmission period the second comparator output signal 28 of the second comparator 26, typically by means of logic 30, to the state corresponding to such a logical value of the second comparator output signal 28 of the second comparator 26 as if there were no reflection. In a second, less preferred embodiment, the timer 41 uses additional control lines to change the filter characteristic of the envelope filter of the envelope generator device after at least a third period of time (Δt3) and after at least a fourth period of time (Δt4) in relation to the first point in time 102 or the third point in time 502 in the transmission period of the amplifier 14 thus at least twice in the transmission period. A quasi-continuous or continuous change with a change function from a fifth point in time, which is shifted by a third time period Δt3 compared to the first point in time 102 or the third point in time 502, is also conceivable. It is particularly preferred to change the filter characteristics of the envelope filter of the envelope generation device within the amplifier 14 at four points in time in the chronological sequence of the first point in time 102 and the third point in time 502. In contrast to the control of the filter characteristic via the timer 41, however, the control of the envelope filter by means of the filter control and based on the second comparator output signal 28 of the second comparator 26 preferred. The filter control is preferably part of the digital processing and filter stage 18. The computer core 2 can also serve as a filter control. In a third embodiment, timer 41 changes the threshold value generation of threshold value signals 24 and/or 27 and, if applicable, further threshold value signals by means of threshold value generation device 29 after at least a fifth time period (Δt5) in relation to first point in time 102 or third point in time 502 of a transmission period, preferably in this way that the generated by the threshold value generating device 29 second threshold value 105 of the second threshold value signal 27 from this point in time (Δt5) falls exponentially with a first time constant τ ₁ to a residual threshold value.

It is obvious to a person skilled in the art that the functionalities shown in this block diagram can also run to a large extent as software on a signal processor. To that extent can one or more components of this block diagram can also be combined into a single device in one implementation.

The following section refers to a device similar to that 4 . The main difference to 1 is now that the analog-to-digital converter 16 does the analog-to-digital conversion in the received signal path not after the generation of the envelope signal by means of an envelope filter in the amplifier 14, but before the generation of the envelope signal in a separate envelope filter 33 located later in the received signal path performs. The envelope filter 33 is in the example 4 ie executed separately from the amplifier 14. Otherwise, the procedure is largely the same in an analogous manner.

Within the meaning of the document presented here, an ultrasonic sensor system 22 includes one or more ultrasonic sensors 1 and one or more data buses 20. The data buses 20 connect the ultrasonic sensors 1 to the control unit 21 of the ultrasonic sensor system 22, which usually includes one or more computer systems with memories, etc . Within the meaning of the document presented here, the ultrasound systems 22 each comprise at least one ultrasound transducer 9 and an evaluation circuit 37. One possible implementation of a proposed evaluation circuit 37 can preferably be a part of the evaluation circuit 37 of the ultrasonic sensor 1 in digital form and another part in analog form. The evaluation circuit 37 of the proposed ultrasonic sensor 1 therefore preferably comprises a digital part 35 and an analog part 36.

The ultrasonic sensor 1 preferably has one or more voltage regulators 39, which supply device parts of the digital part 35 and/or device parts of the analog part 36 with electrical energy from one or more energy sources. A positive supply voltage line 38 and a negative supply voltage line 40 preferably supply the voltage regulator 39 with electrical energy, which in turn at least partially passes this on to the other parts of the device. For the sake of simplicity, these voltage regulators 39 are not shown in most of the figures. If necessary, the computer core 2 controls these voltage regulators 39 in whole or in part. The positive supply voltage line 38 and the negative supply voltage line 40 can also be part of the data bus 20 . The positive supply voltage line 38 and the negative supply voltage line 40 can optionally also serve as data lines of the data bus 20 .

The digital part 35 of the control circuit 37 preferably includes the computer core 2, the control signals 4 for the digital ultrasonic burst generation 2 of the ultrasonic sensor 1, the digital ultrasonic burst generation 3 of the ultrasonic sensor 1, the digitized ultrasonic received signal 17, the envelope filter 33, the processed, digital ultrasonic received signal 34, which is preferred the envelope signal is or includes, the digital processing and filter stage 18 and the filtered received ultrasound signal 19. The digital part 35 of the control circuit 37 preferably includes a second digital comparison logic which, functionally equivalent to the second comparator 26, compares a second threshold value signal 27 with the processed, digital received ultrasound signal 34 , which is preferably the envelope signal or includes, compares. The second digital comparison logic compares the value of the second threshold value signal 27 with the value of the processed, digital ultrasound reception signal 34 and forms the value of the second comparator output signal 28. In this implementation, the second threshold signal 27 is preferably a digital signal that forms the threshold value generation device 29. In this particularly simple case, the corresponding sub-device of the threshold value generation device 29 can be a register, for example, that the computer core 2 can write a data value to and preferably also read via an internal data bus of the digital part 35 (not shown in the figures for the sake of clarity).

The analog part 36 preferably includes the analog ultrasonic transmission stage 6 of the ultrasonic sensor 1. The analog ultrasonic transmission stage 6 of the ultrasonic sensor 1 converts the digital ultrasonic transmission signal 5 into the analog control signal 7 of the ultrasonic sensor 1. The control signal 7 of the ultrasonic sensor 1 drives the oscillating element 8 of the ultrasonic transducer 9. The ultrasonic transmitter stage 6 of the ultrasonic sensor 1 is preferably high-impedance in the temporal reception phase after the transmission phase and the decay phase in order not to overload the output signal of the oscillating element 8, the electrical ultrasonic reception signal 13, too much. Amplifier 14 preferably amplifies and filters electrical ultrasonic reception signal 13 to form amplified electrical ultrasonic reception signal 15. Amplifier 14 and amplified electrical ultrasonic reception signal 15 are preferably part of analog part 36 of control circuit 37.

The analog-to-digital converter 16 preferably converts the amplified electrical ultrasonic received signal 15 to the digitized ultrasonic received signal 17.

In contrast to the examples presented above, in this example the envelope filter 33 is not part of the amplifier 14 in the analog part 36 of the control circuit 37 of the ultrasonic sensor 1, but part of the digital part 35 of the control circuit 37. In contrast to the examples mentioned above, the envelope filter 33 than shifted along the signal path towards the digital conditioning and filtering stage 18.

• • eine Differenz 601 aus erster Zeitdifferenz 101 minus der zweiten Zeitdifferenz 501 und/oder
• • eine Differenz 601 aus zweiter Zeitdifferenz 501 minus der ersten Zeitdifferenz 101 und/oder
• • das Verhältnis von zweiter Zeitdifferenz 501 geteilt durch die erste Zeitdifferenz 101 und/oder
• • das Verhältnis von erster Zeitdifferenz 101 geteilt durch die zweite Zeitdifferenz 501 und/oder
• • eine Verknüpfung der Werte der ersten Zeitdifferenz 101 und der zweiten Zeitdifferenz 501 mit funktionsäquivalenter Wirkung zu den drei vorausgehenden Vergleichsmetoden für den Vergleich der Werte der ersten Zeitdifferenz 101 mit denen der zweiten Zeitdifferenz 501

zu benutzen.The core of the method proposed here is now the method of DE 10 2015 002 269 B3 to use, but as input value the DE 10 2015 002 269 B3 not to use the first time difference 101 or the second time difference 501, but

• • a difference 601 from the first time difference 101 minus the second time difference 501 and/or
• • a difference 601 from the second time difference 501 minus the first time difference 101 and/or
• • the ratio of the second time difference 501 divided by the first time difference 101 and/or
• • the ratio of the first time difference 101 divided by the second time difference 501 and/or
• • a combination of the values of the first time difference 101 and the second time difference 501 with a functionally equivalent effect to the three previous comparison methods for comparing the values of the first time difference 101 with those of the second time difference 501

to use.

The computer core 2 and/or the digital processing and filter stage 18 preferably use this comparison method. For this purpose, the computer core 2 and/or the digital processing and filter stage 18 preferably record the first time difference 101 and/or the second time difference 501.

The technical teaching presented here, in a more digitally-heavy form described here, provides for said first comparator 23 preferably in the analog part 36, which in this digital-heavy version is preferably connected directly to the analog electric ultrasonic received signal 13 of the oscillating element 8 of the ultrasonic transducer 9. Said first comparator 23 preferably again compares the analog output voltages of the ultrasonic transducer 9 of the electrical ultrasonic received signal 13 directly with a fixed analog first threshold value of a first threshold value signal 24. However, the first comparator 23 preferably supplies a binary, preferably digital signal. The preferably digital first comparator output signal 25 of this first comparator 23 is in 4 shown as an example. The first comparator 23 can also be implemented in the digital part 35 in terms of its effect on the signal evaluation if the analog-to-digital converter 16 is in the signal path instead of as in FIG 4 is arranged after the amplifier 14 directly after the ultrasonic transducer 9. However, this is typically not practical since such an arrangement increases the resolution requirements for the analog-to-digital converter 16 . The computer core 2 can also emulate the first comparator 23, if necessary, as a comparison operation. In the last two cases, it is expedient if the position of the analog-to-digital converter 16 is positioned correspondingly earlier in the signal path. The document disclosed here refers to this again by way of example 4 . In the following, the document presented here describes an example of an implementation using an analog first comparator 23 without restricting the technical teaching of the disclosure presented here to the implementation of the comparison using an analog circuit as the first comparator 23 .

The digital first comparator output signal 25 of this exemplary first comparator 23 typically shows a digital oscillation as long as the amplitude of the electric ultrasonic received signal 13 of the ultrasonic transducer 9 still has a significant level. Typically, the fixed first threshold value, which the exemplary first comparator 23 of the ultrasonic sensor system 22 uses for the comparison with the transducer voltage amplitude of the electrical ultrasonic received signal 13 of the ultrasonic transducer 9, has a value such that the first point in time 102 or the third The point in time 502 of the end of this oscillation within a transmission period is not shifted or only shifted by a few oscillation cycles, even with a very close object 11 in the vicinity of the ultrasonic sensor 1, for example when the temperature of the ultrasonic sensor system 22 changes. In this way, for example, the digital processing and filter stage 18 and/or the computer core 2 and/or the envelope filter 33 can, by digitally smoothing and filtering the first comparator output signal 25 of this first comparator 23, determine the end of the decay time at a first point in time 102 of the first edge change 102 of the first comparator output signal 25 or at a third point in time 502 of the third edge change 502 of the first comparator output signal 25 within a transmission period. This first point in time 102 of the first edge change 102 of the first comparator output signal 25 is typically a first temperature-dependent time difference 101 before the second point in time 103 at which the envelope signal of the processed digital ultrasound reception signal 34 falls below the second threshold value of the second threshold value signal 27. However, this second point in time 103 is due to the large Amplitude again practically independent of repercussions from sound reflections on the ultrasonic transducer 9. The third point in time 502 of the third edge change 502 of the first comparator output signal 25 is also a temperature-dependent, second time difference 501 in time before the fourth point in time 503 when the second threshold value of the second threshold signal is undershot 27 processed by the envelope signal, digital ultrasonic received signal 34, but due to the large amplitude is practically independent of repercussions due to sound reflections on the ultrasonic transducer 9.

The digital envelope filter 33 is in the example presented here (see 4 ) is not arranged within the analog amplifier 14, but in the received signal path (13,14,15,16,17,33,34,18,19,2) after the analog-to-digital converter 16. The envelope filter 33 extracts in the example of the 4 from the digitized ultrasound reception signal 17 of the analog-to-digital converter 16 the envelope signal, which is preferably part of the processed, digital ultrasound reception signal 34 or is the processed, digital ultrasound reception signal 34 .

The digital processing and filter stage 18 or the computer core 2 now preferably, for example, based on this first point in time 102 of the first edge change 102 of the first comparator output signal 25 or based on this third point in time 502 of the third edge change 502 of the first comparator output signal 25 only after the elapse of a following third time difference by a timer 41, that the second comparator output signal 28 a second comparison logic, which carries out the comparison functionally equivalent to the second comparator 26, signals the receipt of an echo after evaluation of the processed, digital ultrasound reception signal 34. The timer 41 can also be part of the digital conditioning and filtering stage 18 . Preferably, the computer core 2 controls the timer 41 by means of one or more in the 1 and 4 marked signal lines. Alternatively, the computer core 2 can implement the function of the timer 41 and/or the second comparison logic 26, for example by emulation. The second comparison logic 26, which implements the function of the second comparator 26 in a functionally equivalent manner, preferably starts a counting process of a clock cycle of the timer 41 in the timer 41 when the first point in time 102 or when the third point in time 502 is reached.

The first comparator output signal 25 of the first comparator 23 signals the beginning of the decay process of the ultrasonic transducer 9 by the first edge change 102 at the first point in time 102 or by the third edge change 502 at the third point in time 502. The second comparator output signal 28 of the second comparison logic, which controls the second comparator 26 emulated functionally equivalent, signals the end of the decay process of the ultrasonic transducer 9 by the second edge change 103 at the second point in time 103 or by the fourth edge change 503 at the fourth point in time 503

Here too, a small modification can bring about a corrected indication of a reflection by the second comparator output signal 28 of the second comparison logic which emulates the second comparator 26 . An EXOR gate 30 or, for example, a temporarily functionally equivalent third logic can, for example, signal the end of the decay process of the oscillating element 8 of the ultrasonic transducer 9 . The second comparator output signal 28 and preferably an EXOR control signal 32 of the digital processing and filter stage 18 or of the computer core 2 form the preferred inputs of the EXOR gate 30 or of said third logic. The output 31 of the EXOR gate 30 preferably forms an input signal for the digital processing and filter stage 18.

For this purpose, the EXOR gate 30 or the said third logic switch the second comparator output signal 28 to a first logic level. This preferably takes place at the end of the transmission phase of the ultrasonic transducer 9 for a predefined third time period based on the first point in time 102 or third point in time 502. The first comparator output signal 25 of the first comparator 26 signals the end of the transmission phase of the ultrasonic transducer 9. The first comparator 23 detects the first point in time 102 or the third point in time 502 of the decay of the ultrasonic transducer 9. The length of this third time period preferably corresponds to the length of the first time difference 101 without a reflecting object 11. The ultrasonic sensor system 22 preferably determines the duration of the first time difference 101 by means of a short ultrasonic pulse in said exemplary compensation measurement 504. This is in 2 and 5 shown. The length of the third time period is preferably not based on the length of the second time difference 501. That is, the document presented here proposes defining the length of the third time period as a function of a detected first time difference 101, which the ultrasonic sensor system 22 detects with a short ultrasonic burst 504 in an exemplary compensation measurement 504.determined.

If an object 11 is now spatially close to the ultrasonic transducer 9, then the early-arriving echo and early-arriving echo. reflected ultrasonic bursts 12 the amplitude course 107 of the envelope in the corresponding time range. However, the fourth point in time 503 is now shifted back in time. Since the short ultrasonic pulse of the compensation measurement 504 has a smaller near range, there is a range in which the second point in time 103 has not yet shifted back in time. Due to the EXOR operation of the EXOR gate 30 or with a suitable design of the corresponding alternative third logic, the output of the EXOR circuit 30 switches on the first comparator output signal 25 of the first comparator 23, which was previously present at the output 31 of the EXOR gate 30 the inverted logical value, which corresponds to an echo. The surprising finding disclosed here is that, firstly, the ultrasonic sensor system 22 here, as known from the prior art, is able to detect an object 11 in the close range of the ultrasonic sensor system 22, but without being able to determine the exact location of this object 11 . By using the value of the first time difference 101 as the loading value of the counter of the timer 41, however, this recognition is no longer temperature-dependent and therefore usable. If the counter value of the time counter of the timer 41 reaches this loading value, the timer 41 actuates the EXOR control signal 32 of the EXOR gate or the third logic circuit 30. The digital processing and filter stage 18 thereby recognizes the presence of an object 11 in the close range. With this proposed method, an exact determination of the position of the object 11 in the close range is not possible. However, it is completely sufficient for most applications if the presence of an object 11 can already be detected in this close range. These measures up to this point already improve the reception behavior of the ultrasonic sensor system 22 in the close range.

However, it has also been shown that the digital processing and filter stage 18 or the computer core 2 should carry out an optimized adaptation of the filtering of the envelope signal of the digitally processed, digital ultrasonic reception signal 34 and the comparator output signals 28, 25 in parallel to the above measures in order to actually achieve useful results in the automotive sector. Both measures, the one described immediately above and the one described below, result in an improvement on their own. Experience has shown that these two measures are typically not sufficient on their own for automotive applications.

The following section deals with the parameterization of the envelope filter 33, in particular for the time of the main ultrasound measurement 505. In contrast to the prior art, one or more parameters of the envelope filter 33 depend on the first point in time 102 and/or the second point in time 103 and/or the value of the first time difference 101, which the ultrasonic sensor system 22 preferably determines by means of a compensation measurement 504 that preferably immediately precedes it.

The document presented here therefore also proposes that the ultrasonic sensor system 22 use a method for adapting the parameters of the digital envelope filter 33 for filtering the digitized ultrasonic received signal 17 into an envelope signal of the processed, digital ultrasonic received signal 34 . In the sense of the document presented here, the digital envelope filter 33 preferably has a bandpass characteristic. The proposed method again determines the second point in time 103 at which the instantaneous value of the magnitude of the envelope signal of the processed, digital ultrasonic reception signal 34 falls below the second threshold value 105 of the second threshold value signal 27 . The document presented here now proposes that from this specific second point in time 103, for example, the computer core 2 or the digital processing and filter stage 18 switch the bandpass characteristic of the digital envelope filter 33 such that the bandpass characteristic of the envelope filter 33 becomes narrower. The instantaneous value of the envelope signal of the processed, digital ultrasonic reception signal 34 falling below the second threshold value 105 of the second threshold value signal 27 occurs at said second point in time 103 during the compensation measurement 504 or at a fourth point in time 503 during the main ultrasound measurement 505. The bandpass characteristic of the envelope filter 33 is therefore preferably narrower in a certain time range immediately before this switchover at this second point in time 103 or at this fourth point in time 503. At the end of an ultrasonic pulse period, the digital processing and filter stage 18 and/or the computer core 2 therefore preferably set the relevant parameters of the envelope filter 33 and/or the amplifier 14 and/or the other device parts of the ultrasonic sensor system 22 or the ultrasonic sensor 1 for the At the beginning of an ultrasonic pulse period, starting values return again. This typically does not apply to the detected length of the first time difference 101, which is preferably retained until the next measurement of the duration of this first time difference 101 by means of a short ultrasonic pulse in a compensation measurement 504. As a result, the value of the envelope signal from the envelope filter 33 falls with a slower edge. With such a second threshold value signal 27, a nearby object 11 with a so-called “near echo” arriving shortly after the emission of the ultrasonic burst no longer results in the second threshold value 105 of the second threshold value signal 27 being undershot by the envelope signal of the processed, digital ultrasonic reception signal 34. The ultrasonic sensor system 22 can then no longer determine the fourth point in time 503. The digital processing and filter stage 18 and/or the computer core 2 and/or the ultrasonic sensor system 22 and/or the ultrasonic sensor 1 then preferably use the value of the transmission period as a substitute value, which corresponds to the interval between two pulses. They then preferably use this value as a substitute value for the second time difference 501. A nearby object 11 with a so-called “very close echo” arriving shortly after the ultrasonic burst emission of the short ultrasonic burst 10 emitted can also result in the second threshold value 105 being undershot later in time Threshold signal 27 lead at a first point in time 102 through the envelope signal of the processed digital ultrasonic reception signal 34 . The reason is that the oscillation of the ultrasonic transducer 9 has not yet ended and the object 11 is then so close that the short ultrasonic burst of the compensation measurement 504 is also disrupted.

• • Der Zeitwert des Zeitraums der vergangenen Zeit kann dabei die Dauer des Zeitraums sein, der mit dem Ausschalten der Treiberstufen für den Ultraschall-Transducer 9 am Ende der Sendephase zu einem zweiten Zeitpunkt 103 bzw. zu einem vierten Zeitpunkt 503 beginnt. Die digitale Aufbereitungs- und Filterstufe 18 oder der Rechnerkern 2 führen bevorzugt das Umschalten und/oder das Nachregeln von Parametern des digitalen Hüllkurvenfilters 33 in Abhängigkeit von der Zeit ab dem zweiten Zeitpunkt 103 bzw. ab dem vierten Zeitpunkt 503 durch.
• • Alternativ oder auch zeitlich parallel können die digitale Aufbereitungs- und Filterstufe 18 oder der Rechnerkern 2 das Umschalten und/oder das Nachregeln von Parametern des digitalen Hüllkurvenfilters 33 in Abhängigkeit von der Zeit ab dem bereits besprochenen ersten Zeitpunkt 102 bzw. ab dem dritten Zeitpunkt 502, ab dem das digitale erste Komparatorausgangssignal 25 des ersten Komparators 23 keine Oszillationen mehr zeigt, durchführen.
• • Alternativ oder auch zeitlich parallel können die digitale Aufbereitungs- und Filterstufe 18 oder der Rechnerkern 2 auch das Umschalten und/oder das Nachregeln von Parametern des digitalen Hüllkurvenfilters 33 in Abhängigkeit von dem Hüllkurvensignal des aufbereiteten, digitalen Ultraschallempfangssignals 34 durchführen.

The document presented here proposes that the digital conditioning and filtering stage 18 or the computer core 2 switches the digital envelope filter 33 step by step during a transmission period. The envelope filter 33 is preferably an envelope filter of the digital part 35. In extreme cases, this switching can be done in such a way that the digital processing and filter stage 18 or the computer core 2 continuously sends analog components of the envelope filter 33 that determine the characteristic frequency by means of signaling to the envelope filter 33 via not in the Adjust or adjust the control lines shown in the figures. The digital processing and filter stage 18 or the computer core 2 switch over or readjust the digital envelope filter 33, typically a bandpass filter, preferably as a function of the time that has elapsed since the first point in time 102. Typically, the switching or the readjustment relates to the characteristic frequencies and/or amplitudes of the transfer function of the digital envelope filter 33. Various options for defining the time value of the period of time that has elapsed are possible

• The time value of the period of time that has passed can be the duration of the period that begins when the driver stages for the ultrasonic transducer 9 are switched off at the end of the transmission phase at a second point in time 103 or at a fourth point in time 503 . The digital processing and filter stage 18 or the computer core 2 preferably performs the switching and/or readjustment of parameters of the digital envelope filter 33 depending on the time from the second point in time 103 or from the fourth point in time 503.
• • Alternatively or at the same time, the digital processing and filter stage 18 or the computer core 2 can switch over and/or readjust parameters of the digital envelope filter 33 depending on the time from the already discussed first point in time 102 or from the third point in time 502 , from which the digital first comparator output signal 25 of the first comparator 23 no longer shows any oscillations, perform.
• Alternatively or at the same time, the digital processing and filter stage 18 or the computer core 2 can also switch over and/or readjust parameters of the digital envelope filter 33 depending on the envelope signal of the processed digital ultrasonic received signal 34 .

In the latter case, a step-by-step switchover may require further comparators and/or comparison logic and/or comparison operations or devices that are functionally equivalent to these and that carry out these switchovers as a function of corresponding further switching thresholds with corresponding further switching threshold signals.

A threshold-value generating device 29 preferably generates the threshold-value signals 24 and 27 and possibly further threshold-value signals. The digital processing and filter stage 18 and/or the computer core 2 preferably control the threshold value generation device 29 and the generation of the threshold value signals 24 and 27 and the generation of any further threshold value signals by the threshold value generation device 29. The threshold value generation device 29 preferably generates the threshold value signals 24 and 27 and, if necessary the further threshold value signals depending on the time since the first point in time 102 or the time since the third point in time 502 and/or on the time since the second point in time 103 or the time since the fourth point in time 503 and/or depending on the first time difference 101.

As a result, a faster falling edge of the amplitude curve 107 of the envelope signal of the processed, digital ultrasonic received signal 34 is obtained, whereby the ultrasonic sensor system 22 is sooner able to detect a reflection of objects 11 in the close range.

Adapted to this system-typical envelope curve of the amplitude curve 107 of the envelope signal of the processed, digital Ultra sound reception signal 34, a second threshold value signal 27 falling exponentially over time can now additionally be specified. In this case, the second comparison logic, whose function preferably corresponds to that of a second comparator 26, detects, for example, when the amplitude profile 107 of the envelope signal of the processed, digital ultrasound reception signal 34 falls below the second threshold value signal 27. This occurs at the second point in time 103 or at the fourth point in time 503. The exponential drop in the value of second threshold value signal 27 to a predetermined or otherwise determined residual threshold value with a predetermined or determined first time constant τ ₁ then begins with a time delay of a third time period compared to said first point in time 102 within the transmission period. The duration of the third time period preferably depends on the duration of the first time difference 101 or the difference 601 from the second time difference 501 and the first time difference 101 .

The basic method is therefore, on the one hand, a method for evaluating the electrical ultrasonic reception signal 13 of a piezoelectric ultrasonic transducer 9. In this process, a first comparator 23 or a functionally equivalent device compares in a first step the instantaneous value of the electrical ultrasonic reception signal 13 of the ultrasonic transducer 9 or a signal derived therefrom with a first threshold value and forms a digital first comparator output signal 25 or the like depending on the result. In a second step of the basic method, the amplifier 14 forms the amplified electrical ultrasonic reception signal 15, preferably with amplification and filtering of the electrical ultrasonic reception signal 13. The analog-to-digital converter 16 preferably converts the amplified electrical ultrasonic reception signal 15 into a digitized ultrasonic reception signal 17. An envelope filter 33 typically forms a processed, digital received ultrasound signal 34 from the digitized received ultrasound signal 17. The processed, digital received ultrasound signal 34 preferably includes an envelope signal or is an envelope signal. The parameters of the filtering in the envelope filter 33 are preferably designed to be switchable or controllable. In a next step of the basic method, a threshold value generating device 29 forms the preferably analog first threshold value signal 24 and the preferably digital second threshold value signal 27 and possibly further threshold value signals. In particular, the threshold value generation device 29 can generate this and other threshold value signals 24 and 27 by filtering from the envelope signal of the processed, digital ultrasound reception signal 34 . The threshold value generation device 29 can also generate this and other threshold value signals 24 and 27 by filtering from the electric ultrasonic received signal 13 of the ultrasonic transducer 9 . Typically, the second threshold value signal 27 is in comparison to the first threshold value signal 24 such that the first comparator 23 switches electrical ultrasonic reception signal 13 at higher amplitudes than the second comparison logic, which emulates the second comparator 26 . This second comparison logic, which emulates the second comparator 26, then compares the amplitude profile 107 of the envelope signal of the processed, digital ultrasonic reception signal 34 with the second threshold value 105 of the second threshold signal 27. The output signal 28 of the second comparison logic, which emulates the second comparator 26, gives the detected echoes again. In the close range, the output signal 31 of the EXOR gate 30 reproduces the detected echoes, with the signaling in the close range only saying that an object is in the close range. Therefore, the computer core 2 can optionally signal the output signal 28 of the second comparison logic, which emulates the second comparator 26, or the output signal 31 of the EXOR gate 30 directly to the control device 21. According to the invention, the determination of the first point in time 102 or the third point in time 503 of the decay of the ultrasonic transducer 9 is of particular importance the activation of the ultrasonic transducer 9 no longer shows a signal. This event at the first point in time 102 or at the third point in time 503 typically starts said timer 41. The computer core 2 and/or the digital processing and filter stage 18 stop the timer 41 at the end of a transmission period and then preferably set the timer 41 to a predefined one value back.

This timer 41 switches the second output signal 28 of the second comparison logic, which emulates the second comparator 26, to the other for a predetermined first time period Δt1 after the first point in time 102 or after the third point in time 503 of the decay of the ultrasonic transducer (TR). logical value according to the example. So for example from 1 to 0 and vice versa depending on the system design.

This method according to the invention described above corresponds to a device according to the invention in the form of an ultrasonic sensor system 22, which carries out the corresponding method at least in part. The device according to the invention is used to detect the presence of objects in the close range of an ultrasonic measuring system according to the invention, in particular in an automobile. It has an ultrasonic transducer 9 whose voltage signal is recorded. An envelope The generating device, which is part of the digital envelope filter 33 of the ultrasonic sensor 1 of the device, determines the said envelope signal of the processed, digital ultrasonic received signal 34 from the digitized ultrasonic received signal 17 of the ultrasonic transducer 9. A threshold generator 29, which is also part of the device, generates a second threshold signal 27 with a second threshold value 105. Furthermore, the device comprises said second logic circuit, which emulates said second comparator 26. Said second logic circuit compares the second threshold value 105 of the second threshold value signal 24 with the amplitude profile 107 of the envelope signal d of the processed, digital ultrasonic reception signal 34. The second logic circuit generates a second comparator output signal 28 as a result of this comparison Logic - eg an EXOR gate 30 - by means of a control signal inverted or set to a fixed value, in particular to logic 1 in accordance with the example. In addition, the device typically has a first comparator 23, which compares the value profile of the electrical ultrasonic received signal 13 ultrasonic transducer 9 with a first threshold value of a first threshold value signal 24, this first threshold value of the first threshold value signal 24 compared to the second threshold value 105 of the second threshold value signal 27 is chosen such that the first comparator 23 switches at higher values of the electrical ultrasonic reception signal 13 of the ultrasonic transducer 9 than the second logic circuit, which emulates a second comparator 26 . As already described above, the device has a point in time determination device that determines the first point in time 102 or the third point in time 502 after the end of the active control of the ultrasonic transducer 9, from which the values of the electrical ultrasonic received signal 13 of the ultrasonic transducer 9 are no longer sufficient to to switch the first comparator 23.

This time determination device starts a timer 41 by means of a start signal. The timer 41 is part of the device. Timer 41 uses control signal 32 to switch second comparator output signal 28 of second logic circuit, which emulates second comparator 26, to a state that corresponds to the logical value that signals that there is no reflection. A third logic 30 or a functionally equivalent device preferably serves as the switching device. The computer core 2 and/or the digital processing and filter stage 18 preferably control this switchover by means of control signaling 32 . The third logic can include an EXOR gate 30 . In that case, an EXOR control signal 32 can then transfer the signaling to the EXOR gate 30 .

In addition, a proposed device preferably has a further feature which alone already leads to an improvement over the prior art, but which alone does not yet meet the modern requirements of the automotive market. Such a device for detecting the presence of objects in the close range of an ultrasonic measuring system 22 again has an ultrasonic transducer 9 whose electric ultrasonic received signal 13 is detected. The device preferably has an envelope generation device 33 that generates a processed, digital ultrasonic reception signal 34 from a digitized ultrasound reception signal 17, which typically includes the digital envelope curve signal. This envelope generator device 33 preferably includes a controllable envelope filter 33. The proposed device again has a threshold generator 29, which generates a second threshold signal 27, which is now preferably digital, with a second threshold value 105, and a second logic circuit, which emulates the function of a second comparator 28. The second logic circuit compares the second threshold value signal 27 with the amplitude curve 107 of the envelope signal of the processed, digital ultrasonic reception signal 34 and generates a second comparator output signal 28 of the second logic circuit 26. The computer core 2 and/or the digital processing and filter stage 18 change at least one characteristic frequency of the controllable Envelope filter 33 during operation of the device at least at one point in time depending on the second comparator output signal 28 of the second logic circuit 26 or correlated to this second comparator output signal 28 of the second logic circuit 26.

In a further embodiment, the device also has a first comparator 23, which compares the electrical ultrasonic reception signal 13 of the ultrasonic transducer 9 with a first threshold value of a first threshold value signal 24, this first threshold value of the first threshold value signal 24 compared to the second threshold value 105 of the second threshold value signal 27 is preferably again selected such that the first comparator 23 switches at higher values of the electrical ultrasonic reception signal 13 of the ultrasonic transducer 9 than the second logic circuit 26. To control the timing, the device again preferably has the said point in time determination device. This determines the first point in time 102 or the third point in time 502 after the end of the active control of the ultrasonic transducer 9 from which the value of the elec Technical ultrasonic received signal 13 of the ultrasonic transducer 9 is no longer sufficient to switch the first comparator 23. In this way, a fixed time reference point is created, which now enables control tasks again. Depending on the elapsed time in relation to this first point in time 102 or this third point in time 502, control tasks for the envelope filter 33 and the threshold value generation 29 can now be carried out in a time-dependent manner. The device typically has a timer 41 for this purpose. The timer 41 can be part of the digital processing and filter stage 18, which after at least a third time period (Δt3) and after at least a fourth time period (Δt4) based on the said first point in time 102 or the third point in time 502, the filter characteristic of the envelope filter 33 of the envelope generator preferably changes at least twice. It is of course conceivable to make this change at many points in time, resulting in a quasi-continuous change in second threshold value signal 27 and/or the parameters of envelope filter 33 from said first point in time 102 or third point in time 502 . In the example of 4 the timer 41 is preferably a digital device and/or logic circuit that generates a digital signal that represents, for example, a value of the duration of the elapsed period of time linearly or non-linearly but strictly monotonically decreasing or strictly monotonically increasing with the progression of time and continuously controls the second threshold signal 24 and/or one or more of the parameters of the envelope filter 33 .

In the case of discrete control, for example by a digital timer 41, this timer 41 can, for example, also control threshold value generation 29 after at least a fifth time period (Δt5) in relation to said first point in time 102 or the third point in time 502 in such a way that the second threshold value 105 of the second threshold value signal falls exponentially with a first time constant τ ₁ to a residual threshold value from this first point in time 102 or from this third point in time 502 . In the 1 and 2 the one or more control lines with which the timer 41 controls the threshold value generation 29 are not shown for a better overview. These lines would start at the timer 41 and end at the threshold generation 29 .

The analog ultrasonic transmission stage 6 of the ultrasonic sensor 1 controls the ultrasonic transducer 9 with the control signal 7 typically at the beginning of a transmission period for the duration of a transmission phase. After the transmission phase, the analog ultrasonic transmitter stage 6 controls the ultrasonic transducer 9 for the duration of a braking phase in such a way that it loses as much energy as possible in a short time in order to decay as quickly as possible. After the end of the braking phase, the ultrasonic transducer 9 continues to oscillate for the duration of a decay phase. The analog ultrasonic transmitter stage 6 is preferably inactive after the oscillation of the ultrasonic transducer 9 in the oscillation decay phase for the remainder of the transmission period in a reception phase. The remainder of the transmission period after the transmission phase and braking phase is divided into decay time and reception time. The transmission periods are typically repeated periodically. A first comparator 23 compares the value of the electrical ultrasonic received signal 13 of the ultrasonic transducer 9 with a first threshold value of the first threshold signal 24, which is typically specified by a threshold generator 29. The first threshold value is preferably selected in such a way that its effect is above the second threshold value 105 of the second threshold value signal 27 . The first comparator output signal 25 of the first comparator 23 is preferably evaluated by a point in time determination device. The time determination device is preferably part of the digital processing and filter stage 18. The computer core 2 can also function as a time determination device. This point in time determination device determines the first point in time 102 or the third point in time 502 after the end of the active control of the ultrasonic transducer 9, after which the value of the electric ultrasonic received signal 13 of the ultrasonic transducer 9 is no longer sufficient to switch the first comparator 23 over. Typically, this first point in time 102 and this third point in time 502 are each in the form of a suitable respective signal at the output of the point in time determination device. This signal typically starts the timer 41. In the example of FIG 4 the digital processing and filtering stage 18 performs the function of the point-in-time detection device. The timer 41 can also be part of the digital processing and filtering stage 18 . The computer core 2 can also work as a timer 41 or include such a timer 41 . Reaching the first point in time 102 or the third point in time 502 within a transmission period thus preferably starts the timer 41 . The end of a transmission period or the beginning of a transmission period preferably resets the timer 41 . The timer 41 typically starts when the analog ultrasonic transmission stage 6 of the ultrasonic sensor 1 is switched off. In a first embodiment, the timer 41 switches for a first time period (Δt1) by means of the logic control signal 32 from the first point in time 102 or third point in time 502 in the relevant transmission period the second comparator output signal 28 of the second logic circuit 26 typically by means of a third logic 30 to the state corresponding to such a logical value of the second comparator output signal 28 of the second Logic circuit 26 corresponds as if there were no reflection. In a second, less preferred embodiment, timer 41 uses additional control lines to change the filter characteristics of envelope filter 33 of the Envelope generator device thus at least twice in the transmission period. A quasi-continuous or continuous change with a change function from a fifth point in time, which is shifted by a third time period Δt3 compared to the first point in time 102 or the third point in time 502, is also conceivable. The change in the filter characteristic of the envelope filter 33 of the envelope generation device at four points in time in the chronological sequence of the first point in time 102 and the third point in time 502 is particularly preferred Base of the second comparator output signal 28 of the second logic circuit 26 preferred. The filter control is preferably part of the digital processing and filter stage 18. The computer core 2 can also serve as a filter control. In a third embodiment, timer 41 changes the threshold value generation of threshold value signals 24 and/or 27 and, if applicable, further threshold value signals by means of threshold value generation device 29 after at least a fifth time period (Δt5) in relation to first point in time 102 or third point in time 502 of a transmission period, preferably in this way that the generated by the threshold value generating device 29 second threshold value 105 of the second threshold value signal 27 from this point in time (Δt5) falls exponentially with a first time constant τ ₁ to a residual threshold value.

It is obvious to a person skilled in the art that the functionalities shown in this block diagram can also run to a large extent as software on a signal processor. In this respect, one or more components of this block diagram can also be combined to form a single device in one implementation.

Since the energy of the 1-pulse echo, ie the short ultrasonic burst 504, is very low, the decay process is hardly disturbed. In the case of extremely close objects 11, the conditions can be reversed by waves running back and forth, so that it makes sense to also allow negative time differences or time relationships smaller than a certain threshold value.

The determination of the first threshold value and possibly the second threshold value 105 of the second threshold value signal 27 is typically temperature-dependent.

1. a) Die erste Zeitdifferenz 101 eines ausgesendeten Ultraschallbursts 10 mit einem Ultraschallpuls ist in etwa zeitlich gleich lang, wie die die zweite Zeitdifferenz 501 eines ausgesendeten Ultraschallbursts 10 mit 16 Ultraschallpulsen.
2. b) Ein ausgesendeter Ultraschallburst 10 mit einem Ultraschallpuls kann als im Nahbereich des Ultraschallsensors 1 noch nicht durch reflektierte Ultraschallbursts 12 des Objekts 11 gestört angenommen werden.

In summary, the inventive solution is based on two basic findings:

1. a) The first time difference 101 of a transmitted ultrasonic burst 10 with one ultrasonic pulse is approximately the same length in time as the second time difference 501 of a transmitted ultrasonic burst 10 with 16 ultrasonic pulses.
2. b) A transmitted ultrasonic burst 10 with an ultrasonic pulse can be assumed to have not yet been disturbed by reflected ultrasonic bursts 12 of the object 11 in the vicinity of the ultrasonic sensor 1 .

A proposed solution is such that from time to time individual ultrasonic bursts 10 emitted have only a few ultrasonic pulses, preferably only exactly one ultrasonic pulse. The ultrasonic sensor 1 detects the first time difference 101 with these short emitted ultrasonic pulses 10 in special compensation measurements 504 . This gives the distance measurements of the ultrasonic sensor a longer range. In the case of objects 11 in the close range of the ultrasonic sensor 1, however, this range is not necessary at all, and is even counterproductive, since it increases the dead area in which the ultrasonic sensor 1 cannot detect anything.

With the help of the longer emitted ultrasonic bursts 10 , the ultrasonic sensor 1 can detect a second time difference 501 , which allows conclusions to be drawn about an object 11 in the close range of the ultrasonic sensor 1 . For example, the ultrasonic sensor 1 can normalize the second time difference 501 to the length of the first time difference 101 and thus assess their relationship to one another. As a result, the ultrasonic sensor 1 can correct out temperature fluctuations.

A reference in the form of a measured value of the first time difference 101 can be established by additional compensation measurement 504 with preferably only exactly one ultrasonic pulse in the transmitted ultrasonic burst 10 . The computer core 2 of the ultrasonic sensor 1 calculates this measured value with the measured value of a typically subsequent main ultrasonic measurement 505 and thus generates a compensation. The measurement sequence is therefore preferably such that first a 1-pulse measurement, said compensation measurement 504, takes place and then preferably the normal measurement, said main ultrasound measurement 505. The rows sequence is preferred, but not expressly mandatory. It is also sufficient to carry out the compensation measurement 504 from time to time. In a less preferred embodiment, the ultrasonic sensor 1 can also store previously measured values for the duration of the second time differences 501 with one or more main ultrasonic measurements 505 and only then evaluate them retrospectively using a first time difference 101 of a subsequent compensation measurement 504. The paper presented here does not recommend this possible procedure.

Advantage

The presence of objects 11 in the vicinity of the ultrasonic sensor 1 can be detected with the aid of the methods and devices presented here. However, the advantages are not limited to this. Due to the procedure proposed here, the measuring method is significantly more independent of parameters and temperature.

character list

• 1 shows a proposed, exemplary device.
• 2 shows the exemplary time amplitude profile 107 of the envelope signal of an ultrasonic burst.
• 3 shows the temperature dependency of the duration of the first time difference 101 of FIG 1 from the temperature.
• 4 largely corresponds to the 1 , but with the envelope filter 33 now not part of the amplifier 14 as in FIG 1 is, but is implemented and arranged in the signal path behind the analog-to-digital converter 16 as a digital envelope filter 33 .
• 5 equals to 1 , the timer 41 no longer inverting the second comparator output signal 28 .
• 6 equals to 4 , the timer 41 no longer inverting the second comparator output signal 28 and the digital processing and filter stage 18 and/or the computer core 2 now preferably evaluating the second comparator output signal 28 directly.
• 7 shows an example of an amplitude curve 107 over time of the envelope signal for a first short ultrasonic burst 504 and a subsequent long ultrasonic burst 505.
• 8th shows the temperature dependency of the first time difference 101 of FIG 1 and 4 until 6 of the temperature and the temperature dependency of the second time difference 501 of the recognized in the development of the technical teaching of this document 1 and 4 until 6 from the temperature.
• 9 shows a first exemplary sequence of exemplary measurement sequences.
• 10 shows a second exemplary course of exemplary measurement sequences.
• 11 equals to 5 with the difference that it has no timer 41.
• 12 equals to 3 with the difference that it has no timer 41.
• 13 equals to 9 with the difference that the ultrasonic sensor 1, after having concluded in the fourth step 903 the presence of an object 11 in the close range of the ultrasonic sensor 1, now switches to main ultrasonic measurements 505 with short ultrasonic pulses 10 until the object 11 disappears from the close range of the ultrasonic sensor 1.
• 14 equals to 10 with the difference that the ultrasonic sensor 1, after it has concluded in the sixth step 1005 that an object 11 is present in the close range of the ultrasonic sensor 1, now switches to main ultrasonic measurements 505 with short transmitted ultrasonic pulses 10 until the object 11 has disappeared from the close range of the ultrasonic sensor 1 .

Description of the figures

figure 1

1 shows a proposed, exemplary device. The device represents an ultrasonic sensor system 22. The ultrasonic sensor system 22 comprises a control unit 21 of the ultrasonic sensor system 22 and one or more ultrasonic sensors 1. The ultrasonic sensor 1 comprises an evaluation circuit 37. The evaluation circuit 37 comprises a computer core 2. A data bus 20 connects the computer core 2 of the ultrasonic sensor 1 with the control unit 21 of the ultrasonic sensor system 22. The computer core 2 generates control signals 2 for the digital ultrasonic burst generation 3 of the ultrasonic sensor 1. It is expedient if the computer core 2 may request status information for the digital ultrasonic burst generation 3 of the ultrasonic sensor 1 via an internal data bus of an internal control circuit 37 can. The digital ultrasonic burst generation 3 of the ultrasonic sensor 1 generates a digital ultrasonic transmission signal 5. The analog ultrasonic transmission stage 6 of the Ultra The sound sensor 1 drives the preferably piezoelectric oscillating element 8 of the ultrasonic transducer 9 by means of the control signal 7 of the ultrasonic sensor 1 . The digital ultrasonic burst generator 3 of the ultrasonic sensor 1 and the ultrasonic burst generator 3 of the ultrasonic sensor 1 are typically part of the evaluation circuit 37 with the control signals for the digital ultrasonic burst generator 3 of the ultrasonic sensor 1 and with the digital ultrasonic transmission signal 5 and with the control signal 7 of the ultrasonic sensor 1. The control signal 7 In the transmission phase, typically the oscillating element 8 of the ultrasonic transducer 9 excites the first mechanical oscillations, which the oscillating element 8 then transmits to the surrounding air and emits as an ultrasonic burst 10 emitted.

The control signal 7 preferably dampens the first mechanical oscillations of the oscillating element 8 of the ultrasonic transducer 9 in the subsequent decay phase.

An ultrasonic burst 12 reflected by an object 11 excites the oscillating element 8 of the ultrasonic transducer 9 to perform second mechanical oscillations in the subsequent reception phase. The oscillating element 8 converts these second mechanical oscillations of the oscillating element 8 into an electrical ultrasonic reception signal 13 due to its typically present piezoelectric properties. An amplifier 14 converts the electrical ultrasound reception signal 13 into an amplified electrical ultrasound reception signal 15. In this example, the amplifier 14 preferably comprises the 1 an envelope generator with an envelope filter. The envelope filter generates, for example, an envelope signal from the typically amplified received electrical ultrasonic signal 13 , which is preferably part of the amplified received electrical ultrasonic signal 15 . The amplified electrical ultrasound reception signal 15 can therefore also be a signal bundle in the sense of the document presented here. Typically, the evaluation circuit 37 includes the electric ultrasonic received signal 13 and the amplifier 14 with the envelope filter and the amplified electric ultrasonic received signal 15.

A threshold-value generation device 29 generates, for example, a first threshold-value signal 24 that signals a first threshold value to a first comparator 23 . The evaluation circuit 37 preferably comprises the threshold value generation device 29 and the first threshold value signal 24 and the first comparator 23.

The first comparator 23 or a functionally equivalent sub-device of the evaluation circuit 37 compares this signaled first threshold value of the first threshold value signal 24 with the value of the electrical ultrasound reception signal 13 or a signal derived therefrom and generates a first comparator output signal 25 depending on the result of this comparison. The evaluation circuit 37 comprises typically the first comparator output signal 25.

An analog-to-digital converter 16 preferably converts the amplified electrical ultrasonic received signal 15 into a digitized ultrasonic received signal 17. Since the amplified electrical ultrasonic received signal 15 in the example of FIG 1 comprises or is the envelope signal, the analog-to-digital converter 16 preferably converts the analog envelope signal in the amplified electric ultrasonic received signal 15 into a digitized envelope signal. The digitized envelope signal is preferably a sequence of digitized sampled values of the analog envelope signal in the amplified electrical ultrasound reception signal 15. This sequence of digitized sampled values of the analog envelope signal is preferably a sequence of sampled values which the analog-to-digital converter 16 takes essentially at equidistant sampling times determined as the values of the analog envelope curve signal present at these sampling times in the amplified electric ultrasonic received signal 15 . The evaluation circuit 37 typically includes the analog-to-digital converter 16.

The evaluation circuit 37 uses the first comparator 23 and/or a functionally equivalent sub-device of the evaluation circuit 37 to determine a first time 102 of the first edge change 102 of the first comparator output signal 25. This first time 102 of the first edge change 102 of the first comparator output signal 25 represents the time from which the evaluation circuit 37 assumes the beginning of the reception phase and the end of the decay phase. Thus, the first edge change 102 of the first comparator output signal 25 signals the time of the start of the reception phase and the end of the decay phase.

The technical teaching of the document presented here proposes that the ultrasonic sensor 1 first emits one or more short ultrasonic bursts 504 and then one or more long ultrasonic bursts 505. The ultrasonic sensor 1 detects the first point in time 102 preferably with the aid of a short ultrasonic burst 504 First point in time 102 determined from one or more short ultrasonic bursts 504 corresponds to a third point in time 502, which ultrasonic sensor 1 determines in an analogous manner with the aid of one or more long ultrasonic bursts 505.

The threshold-value generation device 29 generates, for example, a second threshold-value signal 27 that signals a second threshold value to a second comparator 26 . The evaluation circuit 37 preferably includes the second threshold value signal 27 and the second comparator 26.

The second comparator 26 or a functionally equivalent sub-device of the evaluation circuit 37 compares this signaled second threshold value of the second threshold value signal 27 with the value of the amplified electrical ultrasound reception signal 15 or a signal derived therefrom and generates a second comparator output signal 28 depending on the result of this comparison. The evaluation circuit 37 typically includes the second comparator output signal 28.

With the aid of the second comparator 26 and/or a functionally equivalent sub-device of the evaluation circuit 37, the evaluation circuit 37 determines a second point in time 103 of the second edge change 103 of the second comparator output signal 28. This second point in time 103 of the second edge change 103 of the second comparator output signal 28 represents the point in time from which the evaluation circuit 37 assumes the arrival of an ultrasonic burst 12 reflected by an object 11 . The second edge change 103 of the second comparator output signal 28 thus signals the point in time of an object echo of an object 11 in the sense of the document presented here.

The technical teaching of the document presented here proposes that the ultrasonic sensor 1 first emits one or more short ultrasonic bursts 504 and then one or more long ultrasonic bursts 505. The ultrasonic sensor 1 detects the second point in time 103 preferably with the aid of a short ultrasonic burst 504 Second point in time 103 ascertained from one or more short ultrasonic bursts 504 corresponds to a fourth point in time 503, which ultrasonic sensor 1 ascertains in an analogous manner with the aid of one or more long ultrasonic bursts 505.

Immediately after the end of the decay time at the first point in time 102 or at the third point in time 502, the value of the envelope signal of the amplified electrical ultrasonic received signal 15 does not fall below the second threshold value of the second threshold value signal 27, since the oscillating element 8 of the ultrasonic transducer 9 has not yet fully settled.

The elaboration of the proposal presented here showed that the amount of the first time difference 101 between the first time 102 and the second time 103 without a reflecting object 11 in the vicinity of the ultrasonic sensor 1 is equal to the second time difference 501 between the third time of the third edge change 502 of the first comparator output signal 25 and the subsequent fourth point in time 503 of the fourth edge change of the second comparator output signal 28 .

The elaboration of the proposal presented here also revealed that the absolute value of the first time difference 101 between the first point in time 102 and the second point in time 103 with a reflecting object 11 in the vicinity of the ultrasonic sensor 1 is smaller than the second time difference 501 between the third point in time of the third edge change 502 of the first comparator output signal 25 and the subsequent fourth point in time 503 of the fourth edge change of the second comparator output signal 28 .

The evaluation circuit 37 includes a digital processing and filtering stage 18. The digital processing and filtering stage 18 preferably evaluates the digitized received ultrasound signal 17 and generates a filtered received ultrasound signal 19 and possibly further data and/or signals. The digital processing and filtering stage 18 preferably makes the filtered ultrasound reception signal 19 and any additional data and/or signals available to the computer core 2 for forwarding to the control unit 21 of the ultrasound sensor system 22 and/or for further processing and/or compression.

The computer core 2 and/or the digital processing and filter stage 18 preferably use one or more short ultrasonic bursts 504 to determine one or more first time differences 101 between the respective first points in time 102 and the respective second points in time 103, which are suitable for a measurement with a respective short ultrasonic burst 504. surrendered. The computer core 2 and/or the digital processing and filter stage 18 preferably determine an averaged first time difference 101 from a plurality of first time differences 101, for example by averaging.

The computer core 2 and/or the digital processing and filter stage 18 preferably start a timer 41 at a third point in time 502 during the measurement by means of a long ultrasonic burst 505. The timer 41 typically now counts up a time value with a counting cycle. If the time value of the timer 41 reaches the time value of the first time difference 101 or the mean first time difference 101 plus a small predefined tolerance value, the timer 41 inverts by means of the EXOR link 30 or a function equivalent Sub-device of evaluation circuit 37 blocks second comparator output signal 28. EXOR link 30 or the functionally equivalent sub-device of evaluation circuit 37 preferably blocks in a small time tolerance window around the point in time at which the time value of timer 41 exceeds the value of first time difference 101 or the The mean first time difference 101 is signaled via the second comparator output signal 28 in order to suppress jitter and noise in this second comparator output signal 28 . In this respect, the EXOR function of the XOR link 30 is an idealization for the sake of simplified representation, but this will not prevent a person skilled in the art. The EXOR link 30 or the functionally equivalent sub-device of the evaluation circuit 37 are part of the evaluation circuit 37.

The EXOR link 30 or the functionally equivalent sub-device of the evaluation circuit 37 generate the output signal 31 of the EXOR gate 30.

The computer core 2 and/or the digital processing and filter stage 18 evaluate the output signal 31 of the EXOR gate 30 and/or the first comparator output signal 25 and/or the time value of the timer 41 and, depending on this, preferably control the timer 41 After evaluating the output signal 31 of the EXOR gate 30 and/or the first comparator output signal 25, the computer core 2 and/or the digital processing and filter stage 18 determine the first point in time 102 and the second point in time 103 and, if applicable, the third point in time 502 and the fourth Time 503 and from this the first time difference 101 and, if applicable, the second time difference 501.

The computer core 2 and/or the timer 41 and/or the digital processing and filter stage 18 preferably control the parameters of the amplifier 14 and the envelope filter contained therein and the threshold value generation device 29 as a function of the time value of the timer 41 1 two signaling lines are drawn accordingly. Instead of special signaling lines, the use of a common internal data bus for setting and/or changing parameters of device parts of the evaluation circuit 37 by the computer core 2 and/or other device parts is also possible.

The controlled parameters can be filter frequencies of the envelope filter and/or gains of amplifier 14 and/or the first threshold value of first threshold signal 24 and/or the second threshold value of second threshold signal 27, which can be changed in a targeted manner over time within a transmission period.

An object 11 in the close range of the ultrasonic sensor 1 leads to a temporal increase in the duration of the second time difference 501 compared to the first time difference 101.

1. i. Ist die Differenz des Betrags der ersten Zeitdifferenz 101 minus dem Betrag der zweiten Zeitdifferenz 501 kleiner (da negativ) als ein minimaler Zeitdifferenzschwellwert, so schließen der Rechnerkern 2 und/oder die digitale Aufbereitungs- und Filterstufe 18 können auf ein Objekt 11 im Nahbereich des Ultraschallsensors 1.
2. ii. Ist die Differenz des Betrags der zweiten Zeitdifferenz 501 minus dem Betrag der ersten Zeitdifferenz 101 größer (da positiv) als ein maximaler Zeitdifferenzschwellwert, so schließen der Rechnerkern 2 und/oder die digitale Aufbereitungs- und Filterstufe 18 können auf ein Objekt 11 im Nahbereich des Ultraschallsensors 1.
3. iii. Ist der Bruch aus dem Betrag der ersten Zeitdifferenz 101 geteilt durch den Betrag der zweiten Zeitdifferenz 501 kleiner als ein minimaler Zeitverhältnisschwellwert, so schließen der Rechnerkern 2 und/oder die digitale Aufbereitungs- und Filterstufe 18 können auf ein Objekt 11 im Nahbereich des Ultraschallsensors 1.
4. iv. Ist der Bruch aus dem Betrag der zweiten Zeitdifferenz 501 geteilt durch den Betrag der ersten Zeitdifferenz 101 größer als ein maximaler Zeitverhältnisschwellwert, so schließen der Rechnerkern 2 und/oder die digitale Aufbereitungs- und Filterstufe 18 können auf ein Objekt 11 im Nahbereich des Ultraschallsensors 1.

The computer core 2 and/or the digital processing and filter stage 18 can thus infer an object 11 in the vicinity of the ultrasonic sensor 1 in four different ways from the first time difference 101 in relation to the second time difference 501:

1. i. If the difference in the amount of the first time difference 101 minus the amount of the second time difference 501 is smaller (since it is negative) than a minimum time difference threshold value, then the computer core 2 and/or the digital processing and filter stage 18 can conclude that an object 11 is in the vicinity of the ultrasonic sensor 1.
2. ii. If the difference in the amount of the second time difference 501 minus the amount of the first time difference 101 is greater (because it is positive) than a maximum time difference threshold value, then the computer core 2 and/or the digital processing and filter stage 18 can conclude that an object 11 is in the vicinity of the ultrasonic sensor 1.
3. iii. If the fraction of the amount of the first time difference 101 divided by the amount of the second time difference 501 is less than a minimum time ratio threshold value, then the computer core 2 and/or the digital processing and filter stage 18 can conclude that an object 11 is in the vicinity of the ultrasonic sensor 1.
4. IV. If the fraction of the amount of the second time difference 501 divided by the amount of the first time difference 101 is greater than a maximum time ratio threshold value, then the computer core 2 and/or the digital processing and filter stage 18 can conclude that an object 11 is in the vicinity of the ultrasonic sensor 1.

Instead, the computer core 2 can also transmit the time value of the first point in time 102 and the time value of the second point in time 103 and the time value of the third point in time 502 and the time value of the fourth point in time 503 to the control device 21 via the data bus 20 . In this case, the control unit 21 preferentially carries out the comparisons i to iv given above instead of the computer core 2 .

Instead, the computer core 2 can also transmit the time value of the first time difference 101 and the time value of the second time difference 501 to the control unit 21 via the data bus 20 . In that case, the controller 21 performs the above flat comparisons i to iv instead of the computer core 2 are also preferred.

If the computer core 2 and/or the digital processing and filter stage 18 conclude that an object 11 is present in the vicinity of the ultrasonic sensor 1, the computer core 2 preferably signals this result to the control unit 21, preferably via the data bus 20.

It is obvious to a person skilled in the art that, in the case of an evaluation using the immediately above alternatives i to iv, an evaluation using an EXOR link 30 or a functionally equivalent sub-device of the evaluation circuit 37 is no longer necessary. In that case, the timer 41 and the EXOR link 30 or the functionally equivalent sub-device of the evaluation circuit 37 can be dispensed with. In that case, the second comparator output signal 28 replaces the output signal 31 of the EXOR gate 30; as a control signal for the digital processing and filter stage 18 or the computer core 2.

figure 2

2 shows the exemplary time amplitude profile 107 of the envelope signal of an ultrasonic burst. In the case of 1 it is the envelope signal of the amplified electrical ultrasound reception signal 15. In the case of 4 the y-axis represents the amplitude profile 107 of the envelope signal. This amplitude profile 107 is specified here as an example in LSB of the analog-to-digital converter 16 At the beginning, during the transmission phase, the amplitude curve 107 over time has an overdrive of the analog-to-digital converter 16 and/or the amplifier 14 by the amplitude curve 107 of the envelope signal. At a first point in time 102, the amplitude of the electric ultrasound reception signal 13 falls below the first threshold value of the first threshold value signal 24. At this first point in time 102, the first comparator output signal 25 changes its logic state and has a first edge. After a first time difference 101 has passed, the amplitude curve 107 of the envelope signal falls below the second threshold value 105 of the second threshold value signal 27 at a second point in time 103.

figure 3

3 shows the temperature dependency of the time duration of the first time difference 101 of the recognized in the development of the technical teaching of this document 1 from the temperature of the ultrasonic transducer 9.

figure 4

4 largely corresponds to the 1 . However, the envelope filter 33 is now not part of the amplifier 14 as in FIG 1 , but implemented and arranged in the signal path behind the analog-to-digital converter 16 as a digital envelope filter 33 . The second comparison logic, which is functionally equivalent to the second comparator 26, compares the second threshold value of the second threshold value signal 27 with the value of the processed, digital ultrasound reception signal 34. In the example of FIG 4 amplifies and / or filters the amplifier 14, the electrical ultrasound reception signal 13 to the amplified electrical ultrasound reception signal 15. In the example of 4 Typically, the amplifier 14 does not include an envelope filter. The envelope filter 33 is in the example 4 unlike in the example 1 preferably done digitally. Therefore in the example the 4 the envelope filter 33 in the digital part 35 in the signal path behind the analog-to-digital converter 16 is arranged by way of example. In the example of 4 therefore, the amplified ultrasonic received electrical signal 15 typically does not include the envelope signal. In the example of 4 the analog-to-digital converter 16 converts the amplified electrical ultrasonic received signal 15 to the digitized ultrasonic received signal 17. The envelope filter 33 filters in the example of FIG 4 the digitized ultrasonic received signal 17 to the processed, digital ultrasonic received signal 34. The processed, digital ultrasonic received signal 34 preferably comprises the envelope signal or the processed, digital ultrasonic received signal 34 is preferably the digitized envelope signal. The analog-to-digital converter 16 is thus in the example 4 arranged in front of the processed, digital ultrasound reception signal 34 in the signal path. The second comparison logic, which is functionally equivalent to the second comparator 26, compares the second threshold value of the second threshold value signal 27 with the value of the processed, digital ultrasonic reception signal 34. And depending on the result of this comparison, generates the second comparator output signal 28 already described 4 the second comparison logic is drawn in with the symbol for the second comparator 26 in order to clarify the functional equivalence.

The rest of the signal processing 4 corresponds to the 1 .

figure 5

5 equals to 1 , where now the timer 41 the second comparator output signal 28 no longer inverted. The digital processing and filter stage 18 and/or the computer core 2 now evaluate the second comparator output signal 28, preferably directly.

figure 6

6 equals to 4 , the timer 41 no longer inverting the second comparator output signal 28 . The digital processing and filter stage 18 and/or the computer core 2 now evaluate the second comparator output signal 28, preferably directly.

figure 7

7 shows an example of an amplitude curve 107 over time of the envelope signal for a first short ultrasonic burst 504 and a subsequent long ultrasonic burst 505, here by way of example in LSB of the analog-to-digital converter 16. In the case of 1 it is the envelope signal of the amplified electrical ultrasound reception signal 15. In the case of 4 it is the envelope signal of the processed, digital ultrasonic reception signal 34. It is irrelevant for the method used whether the envelope signal is analog ( 1 ) or digital ( 4 ) exists. The first comparator 23 typically compares the value of the amplitude of the electrical ultrasonic reception signal 13 with the first threshold value of the first threshold signal 24. If the amplitude of the electrical ultrasonic reception signal 13 falls below the first threshold value of the first threshold signal 24, the first comparator 23 signals the first point in time 102 a first flank change of his first

Comparator output signal 25. This edge change of the first comparator output signal 25 is in the 7 drawn. The scale of the Y-axis does not refer to the first comparator output signal 25. The reader can assume that the value of the first comparator output signal 25 changes from a first logical value to a second logical value at the first point in time 102. If the transmission of a new ultrasonic pulse begins after the end of the transmission period 506 after the last start of the transmission of the last ultrasonic pulse, the value of the first comparator output signal 25 preferably changes from the second logical value, preferably back to a first logical value.

The example of 7 shows a first ultrasonic envelope signal 504 followed by a second ultrasonic envelope signal 505 as parts of the amplitude profile 107 of the amplitude 106 of the envelope signal. In the example of 7 An exemplary compensation measurement in the form of the first ultrasonic envelope signal 504 precedes an exemplary main ultrasonic measurement in the form of a second ultrasonic envelope signal 505 . The ultrasonic sensor 1 preferably uses an ultrasonic burst with only a few, preferably only one, ultrasonic pulse for the compensation measurement 504 . The ultrasonic sensor 1 preferably uses an ultrasonic burst with a plurality of, preferably more than two, ultrasonic pulses for the main ultrasonic measurement 505 .

When the first point in time 102 is reached, the ultrasonic sensor 1 reaches the end of the transmission phase for the compensation measurement 504. As the oscillating element 8 of the ultrasonic transducer 9 continues to oscillate, the amplitude curve 106 of the envelope signal falls below the first threshold value 105 of the first threshold value signal 27 at a second point in time 103. The time value of the time difference from the second point in time 103 minus the first point in time 102 represents the first time difference 101. This first time difference 101 is the reference value which the ultrasonic sensor 1 or its computer core 2 or its digital processing and filter stage 18 uses for subsequent Main ultrasound measurements 505 with longer ultrasound bursts 10 with multiple ultrasound pulses, assess whether the second time differences 501 then detected deviate so much from this first time difference 101 in terms of absolute value that the ultrasound sensor 1 or its computer core 2 or its digital processing and filter stage 18 must assume that an object 11 is in the vicinity of the ultrasonic sensor 1. When the third point in time 502 is reached, the ultrasonic sensor 1 reaches the end of the transmission phase for the relevant main ultrasonic measurement 505. With the subsequent further oscillation of the oscillating element 8 of the ultrasonic transducer 9, the amplitude profile 106 of the envelope signal again falls below the first threshold value 105 of the first threshold value signal 27 at once fourth point in time 503. The time value of the time difference from the fourth point in time 503 minus the third point in time 502 represents the second time difference 501.

If there is no object 11 in the vicinity of the ultrasonic sensor 1, the oscillating element 8 of the ultrasonic transducer 9 can oscillate unhindered. This is the first operating case below. The elaboration of the proposal presented here showed that under this condition the first time difference 101 does not deviate significantly from the second time difference 501 . In this first operating case, discrepancies between the first time difference 101 and the second time difference 501 can generally be attributed to insignificant disturbances.

However, if an object 11 is in the vicinity of the ultrasonic sensor 1, the oscillating element 8 of the ultrasonic transducer 9 can only oscillate unhindered in the case of the compensation measurement 504. In this case, the ultrasonic burst 10 is still short enough in time that the oscillating element 8 of the ultrasonic transducer 9 can oscillate before the reflected ultrasonic burst 12 reaches the oscillating element 8 again. If the object 11 is therefore located in the vicinity of the ultrasonic sensor 1, the oscillating element 8 of the ultrasonic transducer 9 can no longer oscillate unhindered in the case of the main ultrasonic measurement 505. In this case, the duration of the ultrasonic burst 10 is too long, so that the oscillating element 8 of the ultrasonic transducer 9 has not yet decayed when the reflected ultrasonic burst 12 reaches the oscillating element 8 again. This is the second operating case below. The elaboration of the proposal presented here revealed that the first time difference 101 differs significantly from the second time difference 501 under this condition. In this second operating case, the first time difference 101 is smaller in absolute terms, i.e. shorter in time, than the second time difference 501. The ultrasonic sensor 1 or its computer core 2 or its digital processing and filter stage 18 evaluates this different time length of the first time difference 101 and the second Time difference 501 now off. It is sufficient for this if the ultrasonic sensor 1 or its computer core 2 or its digital processing and filter stage 18 carry out a compensation measurement 504 from time to time and otherwise work with main ultrasonic measurements 505 .

1. i. Der Ultraschallsensor 1 bzw. dessen Rechnerkern 2 oder dessen digitale Aufbereitungs- und Filterstufe 18 bilden die Differenz aus dem Betrag der zweiten Zeitdifferenz 501 minus dem Betrag der ersten Zeitdifferenz 101. Ist der Betrag größer Null plus einem optionalen ersten Vorhalt, so Schließen der Ultraschallsensor 1 bzw. dessen Rechnerkern 2 oder dessen digitale Aufbereitungs- und Filterstufe 18 bevorzugt aus die Anwesenheit eines Objekts 11 im Nahbereich des Ultraschallsensors 1.
2. ii. Der Ultraschallsensor 1 bzw. dessen Rechnerkern 2 oder dessen digitale Aufbereitungs- und Filterstufe 18 bilden die Differenz aus dem Betrag der ersten Zeitdifferenz 101 minus dem Betrag der zweiten Zeitdifferenz 501. Ist der Betrag kleiner Null minus einem optionalen zweiten Vorhalt, so Schließen der Ultraschallsensor 1 bzw. dessen Rechnerkern 2 oder dessen digitale Aufbereitungs- und Filterstufe 18 bevorzugt aus die Anwesenheit eines Objekts 11 im Nahbereich des Ultraschallsensors 1.
3. iii. Der Ultraschallsensor 1 bzw. dessen Rechnerkern 2 oder dessen digitale Aufbereitungs- und Filterstufe 18 teilen den Betrag der zweiten Zeitdifferenz 501 durch den Betrag der ersten Zeitdifferenz 101. Ist der Betrag größer 1 (eins) plus einem optionalen dritten Vorhalt, so Schließen der Ultraschallsensor 1 bzw. dessen Rechnerkern 2 oder dessen digitale Aufbereitungs- und Filterstufe 18 bevorzugt aus die Anwesenheit eines Objekts 11 im Nahbereich des Ultraschallsensors 1.
4. iv. Der Ultraschallsensor 1 bzw. dessen Rechnerkern 2 oder dessen digitale Aufbereitungs- und Filterstufe 18 teilen den Betrag der ersten Zeitdifferenz 101 durch den Betrag der zweiten Zeitdifferenz 501. Ist der Betrag kleiner 1 (eins) minus einem optionalen dritten Vorhalt, so Schließen der Ultraschallsensor 1 bzw. dessen Rechnerkern 2 oder dessen digitale Aufbereitungs- und Filterstufe 18 bevorzugt aus die Anwesenheit eines Objekts 11 im Nahbereich des Ultraschallsensors 1.

The ultrasonic sensor 1 or its computer core 2 or its digital processing and filter stage 18 can, for example, proceed in the following ways:

1. i. The ultrasonic sensor 1 or its computer core 2 or its digital processing and filter stage 18 form the difference between the amount of the second time difference 501 minus the amount of the first time difference 101. If the amount is greater than zero plus an optional first offset, the ultrasonic sensor 1 closes or its computer core 2 or its digital processing and filter stage 18 preferably from the presence of an object 11 in the vicinity of the ultrasonic sensor 1.
2. ii. The ultrasonic sensor 1 or its computer core 2 or its digital processing and filter stage 18 form the difference between the amount of the first time difference 101 minus the amount of the second time difference 501. If the amount is less than zero minus an optional second lead, the ultrasonic sensor 1 closes or its computer core 2 or its digital processing and filter stage 18 preferably from the presence of an object 11 in the vicinity of the ultrasonic sensor 1.
3. iii. The ultrasonic sensor 1 or its computer core 2 or its digital processing and filter stage 18 divides the amount of the second time difference 501 by the amount of the first time difference 101. If the amount is greater than 1 (one) plus an optional third offset, the ultrasonic sensor 1 closes or its computer core 2 or its digital processing and filter stage 18 preferably from the presence of an object 11 in the vicinity of the ultrasonic sensor 1.
4. IV. The ultrasonic sensor 1 or its computer core 2 or its digital processing and filter stage 18 divides the amount of the first time difference 101 by the amount of the second time difference 501. If the amount is less than 1 (one) minus an optional third offset, the ultrasonic sensor 1 closes or its computer core 2 or its digital processing and filter stage 18 preferably from the presence of an object 11 in the vicinity of the ultrasonic sensor 1.

The first through fourth leads are preferably positive. The first to fourth leads can be chosen to be zero. The publication presented here recommends choosing larger amounts for these projections.

The Y axis of the 7 shows an example of scaling for the amplitude curve 106 of the envelope signal, here by way of example in LSB of the analog-to-digital converter 16. In the case of 1 it is the envelope signal of the amplified electrical ultrasound reception signal 15. In the case of 4 is the envelope signal of the processed, digital ultrasonic reception signal 34.

The time axis (X-axis) represents the time in number of past sampling times of the analog-to-digital converter 16 (English: counts).

figure 8

8th shows the temperature dependency of the first time difference 101 of FIG 1 and 4 until 6 of the temperature and the temperature dependency of the second time difference 501 of the recognized in the development of the technical teaching of this document 1 and 4 until 6 from the temperature. This is the first operating case in which there is no object 11 in the vicinity of the ultrasonic sensor 1 . As can easily be seen, the first time difference 101 and the second time difference 501 differ for the same temperatures insignificant. The core of the proposal is therefore to carry out a compensation measurement 504 only from time to time with a temporally short ultrasonic burst 10 with few ultrasonic pulses, preferably with only one ultrasonic pulse, in order to then detect the first time difference 101 and then the subsequent main ultrasonic measurements 505 with temporally longer ones Carry out ultrasonic bursts 505 with a plurality of ultrasonic pulses, to detect the second time difference 501 and to infer the presence of an object 11 in the vicinity of the ultrasonic sensor 1 if the first time difference 101 is significantly shorter in terms of absolute value than the second time difference 501.

figure 9

9 shows a first exemplary sequence of exemplary measurement sequences.

In a first step 900, the ultrasonic sensor 1 carries out a compensation measurement 504 using a short transmitted ultrasonic burst 10 with a few ultrasonic pulses, preferably with only one ultrasonic pulse. In the first step 900, the ultrasonic sensor determines the value of the temporal length of the first time difference 101. The computer core 2 and/or the digital processing and filter stage 18 preferably store the value of the temporal length of the first time difference 101 in a memory of the ultrasonic sensor 1. Typically, the computer core 2 controls this first step 900 with the cooperation of other device parts of the ultrasonic sensor 1. Instead of the computer core 2, the control unit 21 of the ultrasonic sensor system 22 can theoretically also control this first step 900 and/or partially take over functions of the ultrasonic sensor 1 in this first step 900.

In a second step 901, the ultrasonic sensor 1 carries out a main ultrasonic measurement 505 using a long emitted ultrasonic burst 10 with a plurality of ultrasonic pulses. In the second step 901, the ultrasonic sensor 1 determines the value of the temporal length of the second time difference 501. Typically, the computer core 2 controls this second step 901 with the cooperation of other device parts of the ultrasonic sensor 1. Instead of the computer core 2, control unit 21 of the ultrasonic sensor system 22 can theoretically also carry out this second step 901 control and / or partially take over functions of the ultrasonic sensor 1 in this second step 901.

In a third step 902, the ultrasonic sensor 1 compares the value of the length of time of the second time difference 501 with the value of the length of time of the first time difference 101. This can be done, for example, by forming the difference or forming a ratio, as described above. Typically, computer core 2 controls this third step 902 with the participation of other parts of the ultrasonic sensor 1. Typically, the computer core 2 controls this third step 902 with the participation of other parts of the ultrasonic sensor 1. Instead of the computer core 2, control unit 21 of the ultrasonic sensor system 22 can theoretically also carry out this third step 902 control and/or partially take over functions of the ultrasonic sensor 1 in this third step 902 .

Depending on the result of the comparison, the fourth step 903 may follow. If the duration of the second time difference 501 is greater than the duration of the first time difference 101, then in a fourth step 903 the ultrasonic sensor 1 concludes that there is an object 11 in its close range. In this fourth step 903, the computer core 2 preferably signals the control unit 21 of the ultrasonic sensor system 22; the presence of this object 11 in the vicinity of ultrasonic sensor 1. Typically, computer core 2 controls this fourth step 903 with the cooperation of other device parts of ultrasonic sensor 1. Instead of computer core 2, control unit 21 of ultrasonic sensor system 22 can theoretically also control this fourth step 903 and/or functions of the Partially take over ultrasonic sensor 1 in this fourth step 903 .

The third step 902 is followed by the fifth step 904, depending on the result of the comparison. If the time length of the second time difference 501 is less than the time length of the first time difference 101, the ultrasonic sensor 1 concludes in the fifth step 904 that an object is not present 11 in its close range. In this fifth step 904, the ultrasonic sensor 1 then preferably checks whether the number of main ultrasonic measurements 505 since the last compensation measurement 504 has exceeded or reached a maximum number. If this is the case, the ultrasonic sensor 1 preferably carries out a compensation measurement 504 again in a first step 900, with which the cycle typically begins anew. If this is not the case, then the ultrasonic sensor 1 preferably carries out the next main ultrasonic measurement 505 . Before carrying out the next compensation measurement 504 or the next main ultrasound measurement 505, the ultrasound sensor 1 typically waits until the transmission period 506 has elapsed since the start of the transmission of the ultrasound burst 10 immediately preceding in time. Typically, the computer core 2 controls this fifth step 904 with the cooperation of other device parts of the ultrasonic sensor 1. Instead of the computer core 2, the control unit 21 of the ultrasonic sensor system 22 can theoretically also carry out this fifth step 904 control and/or partially take over functions of the ultrasonic sensor 1 in this fifth step 904 .

figure 10

10 shows a second exemplary course of exemplary measurement sequences.

In a first step 1000, the ultrasonic sensor 1 carries out a compensation measurement 504 using a short transmitted ultrasonic burst 10 with a few ultrasonic pulses, preferably with only one ultrasonic pulse. In the first step 1000, the ultrasonic sensor 1 determines the value of the length of time of the first time difference 101. The computer core 2 and/or the digital processing and filter stage 18 preferably store the value of the length of time of the first time difference 101 in a memory of the ultrasonic sensor 1. Typically, the computer core 2 controls this first step 1000 with the cooperation of other device parts of the ultrasonic sensor 1. Instead of the computer core 2, the control unit 21 of the ultrasonic sensor system 22 can theoretically also control this first step 1000 and/or partially take over functions of the ultrasonic sensor 1 in this first step 1000.

In a second step 1001, the ultrasonic sensor 1 carries out an ultrasonic main measurement 505 using a long transmitted ultrasonic burst 10 with a plurality of ultrasonic pulses. However, in the second step 1001, the ultrasonic sensor 1 does not determine as in 9 the value of the length of time of the second time difference 501. Instead, the ultrasonic sensor 1 determines the third point in time 502 and starts the timer 41. Typically, the computer core 2 controls this second step 901 with the cooperation of other device parts of the ultrasonic sensor 1. Typically, the computer core 2 controls this second step 1001 with the cooperation of other device parts of the ultrasonic sensor 1. Instead of the computer core 2, the control unit 21 of the ultrasonic sensor system 22 can theoretically also control this second step 1001 and/or partially take over functions of the ultrasonic sensor 1 in this second step 1001.

In a third step 1002, the ultrasonic sensor 1 preferably changes the value of its timer 41 by the value of a timer increment. The ultrasonic sensor 1 preferably increments the value of the timer 41 in this third step 1002. Typically, the computer core 2 controls this third step 1002 with the cooperation of other device parts of the ultrasonic sensor 1. Instead of the computer core 2, control unit 21 of the ultrasonic sensor system 22 can theoretically also control this third step 1002 and/or partially take over functions of the ultrasonic sensor 1 in this third step 1002 .

In a fourth step 1003, the ultrasonic sensor 1 compares the value of the timer 41 with the value of the first time difference 101. If the value of the timer 41 is less than the first time difference 101 plus a lead that is preferably used, the oscillating element 8 of the ultrasonic transducer 9 of the ultrasonic sensor 1 must not have swung out yet. In that case, the method that ultrasonic sensor 1 carries out jumps back to third step 1002 again. If the value of the timer 41 is greater than the first time difference 101 plus a lead that is preferably used, the oscillating element 8 of the ultrasonic transducer 9 of the ultrasonic sensor 1 should have swung out if there is no object 11 in the vicinity of the ultrasonic sensor 1. In this case, the method that the ultrasonic sensor 1 carries out jumps to the fifth step 1004. Typically, the computer core 2 controls this fourth step 1003 with the cooperation of other device parts of the ultrasonic sensor 1. Instead of the computer core 2, the control unit 21 of the ultrasonic sensor system 22 can theoretically also control this fourth Control step 1003 and/or partially take over functions of ultrasonic sensor 1 in this fourth step 1003 .

In the fifth step 1004, the ultrasonic sensor compares the amplitude profile 107 of the envelope signal with a second threshold value 105. If the magnitude of the amplitude profile 107 of the envelope signal is below the second threshold value 105, the ultrasonic sensor 1 concludes that an object 11 is not present in the vicinity of the ultrasonic sensor 1. In In this case, the ultrasonic sensor 1 continues to carry out the method with the seventh step 1006 . If the magnitude of the amplitude curve 107 of the envelope signal is above the second threshold value 105, then the ultrasonic sensor 1 concludes that an object 11 is present in the vicinity of the ultrasonic sensor 1. In this case, the ultrasonic sensor 1 continues to carry out the method with the sixth step 1005. Typically, computer core 2 controls this fifth step 1004 with the cooperation of other parts of the device of ultrasonic sensor 1. Instead of computer core 2, control unit 21 of ultrasonic sensor system 22 can theoretically also control this fifth step 1004 and/or partially take over functions of ultrasonic sensor 1 in this fifth step 1004.

In the sixth step 1005, the computer core 2 preferably controls this sixth step 1005 with the cooperation of other device parts of the ultrasonic sensor 1. Preferably signals computer core 2 tells the control unit 21 of the ultrasonic sensor system 22 the presence of this object 11 in the vicinity of the ultrasonic sensor 1. Typically, the computer core 2 controls this sixth step 1005 with the cooperation of other device parts of the ultrasonic sensor 1. Instead of the computer core 2, the control unit 21 of the ultrasonic sensor system 22 can theoretically also control this Control sixth step 1005 and / or take over functions of the ultrasonic sensor 1 in this sixth step 1005 partially.

In the seventh step 1006, the ultrasonic sensor 1 preferably checks whether the number of main ultrasonic measurements 505 since the last compensation measurement 504 has exceeded or reached a maximum number. If this is the case, the ultrasonic sensor 1 preferably carries out a compensation measurement 504 again in a first step 1000, with which the cycle typically begins anew. If this is not the case, the ultrasonic sensor 1 preferably carries out the next main ultrasonic measurement 505 in a second step 1001 . Before carrying out the next compensation measurement 504 or the next main ultrasound measurement, the ultrasound sensor 1 typically waits until the transmission period 506 has elapsed since the start of the transmission of the ultrasound burst 10 immediately preceding in time. Typically, the computer core 2 controls this seventh step 1006 with the cooperation of other device parts of the ultrasonic sensor 1. Instead of the computer core, control unit 21 of the ultrasonic sensor system 22 can theoretically also control this seventh step 1006 and/or partially take over functions of the ultrasonic sensor 1 in this seventh step 1006.

figure 11

11 equals to 5 with the difference that it has no timer 41. You can therefore only do one procedure accordingly 9 carry out.

figure 12

12 equals to 3 with the difference that it has no timer 41. You can therefore only do one procedure accordingly 9 carry out.

figure 13

13 equals to 9 with the difference that the ultrasonic sensor 1, after having concluded in the fourth step 903 the presence of an object 11 in the close range of the ultrasonic sensor 1, now switches to main ultrasonic measurements 505 with short ultrasonic pulses 10 until the object 11 disappears from the close range of the ultrasonic sensor 1. In the extreme case, the ultrasonic sensor 1 therefore only carries out compensation measurements 504 with preferably only one ultrasonic pulse per ultrasonic burst 10 emitted until the object 11 disappears from the close range of the ultrasonic sensor 1 . Ultrasonic sensor 1 therefore concludes that an object 11 is in its close range and, if such an object 11 is in the close range of ultrasonic sensor 1, shortens the length of time of the transmitted ultrasonic bursts 10 To detect distance of the object 11 in its vicinity. In this case of an object 11 in the close range of the ultrasonic sensor 1, the ultrasonic sensor 1 would not be able to detect the distance between the ultrasonic sensor 1 and the object 11 without this temporal shortening of the emitted ultrasonic bursts 10, since the reflected ultrasonic burst 12 in the case of an unshortened emitted ultrasonic burst 10 would arrive at a time when the oscillating element 8 of the ultrasonic sensor 1 would not have swung out.

In a sixth step 905, the ultrasonic sensor 1 emits a shortened ultrasonic burst 10 with a second length of time, which is preferably shorter than the first length of time of the emitted ultrasonic burst 10, which the ultrasonic sensor 1 emits in the second step 901. The second temporal length of the transmitted ultrasonic burst 10 in this sixth step 905 is preferably equal to the temporal length of the short transmitted ultrasonic bursts 10 that the ultrasonic sensor 1 transmits in the first step 900 for the compensation measurement 504 . Thus, in a preferred embodiment, the transmitted ultrasonic bursts 10 of the sixth step 905 typically correspond to the ultrasonic bursts that the ultrasonic sensor 1 uses for the compensation measurement 504 in the first step 900 . In this sixth step 905, the ultrasonic sensor 1 detects the distance to the object 11 in its close range.

In a seventh step 906, the ultrasonic sensor 1 checks whether the object 11 is still in its close range. For this purpose, the ultrasonic sensor 1 compares the distance between the object 11 and the ultrasonic sensor 1, which is detected with the short emitted ultrasonic burst 10, with a distance threshold value. If this detected distance is less than this distance threshold value, object 11 is still in the close range of ultrasonic sensor 1 and ultrasonic sensor 1 continues with sixth step 905 . If this detected distance is greater than this distance threshold value, then object 11 is no longer in the vicinity of ultrasonic sensor 1 and ultrasonic sensor 1 moves with it first step 900. If the first step 900 corresponds to the sixth step 905 and the ultrasonic sensor 1 determines a first time difference 101 in the sixth step 905, the ultrasonic sensor 1 can also continue directly with the second step 901.

figure 14

14 equals to 10 with the difference that the ultrasonic sensor 1, after it has concluded in the sixth step 1005 that an object 11 is present in the close range of the ultrasonic sensor 1, now switches to main ultrasonic measurements 505 with short transmitted ultrasonic pulses 10 until the object 11 has disappeared from the close range of the ultrasonic sensor 1 . In the extreme case, the ultrasonic sensor 1 therefore only carries out compensation measurements 504 with preferably only one ultrasonic pulse per ultrasonic burst 10 emitted until the object 11 disappears from the close range of the ultrasonic sensor 1 . The ultrasonic sensor 1 therefore concludes that there is an object 11 in its close range and then, if such an object 11 is in the close range of the ultrasonic sensor 1, shortens the length of time of the transmitted ultrasonic bursts 10. The ultrasonic sensor 1 is thus in a position to determine the distance of the To detect object 11 in its vicinity. In this case of an object 11 in the close range of the ultrasonic sensor 1, the ultrasonic sensor 1 would not be able to detect the distance between the ultrasonic sensor 1 and the object 11 without this temporal shortening of the transmitted ultrasonic bursts 10, since the reflected ultrasonic burst 12 would not be shortened at a emitted ultrasonic bursts 10 would arrive at a point in time at which the oscillating element 8 of the ultrasonic sensor 1 would not have swung out.

In an eighth step 1007, the ultrasonic sensor 1 emits a shortened ultrasonic burst 10 with a second time length, which is preferably shorter than the first time length of the ultrasonic burst 10, which the ultrasonic sensor 1 emits in the second step 1001. The second temporal length of the transmitted ultrasonic burst 10 in this eighth step 1007 is preferably equal to the temporal length of the short transmitted ultrasonic bursts 10 that the ultrasonic sensor 1 transmits in the first step 1000 for the compensation measurement 504 . In a preferred embodiment, the transmitted ultrasonic bursts 10 of the eighth step 1007 typically correspond to the ultrasonic bursts that the ultrasonic sensor 1 uses for the compensation measurement 504 in the first step 1000 . In this sixth step 905, the ultrasonic sensor 1 detects the distance to the object 11 in its close range.

In a ninth step 1008, the ultrasonic sensor 1 checks whether the object 11 is still in its close range. For this purpose, the ultrasonic sensor 1 compares the distance of the object 11 to the ultrasonic sensor 1 detected with the short ultrasonic burst 10 in the eighth step 1007 with a distance threshold value. If this detected distance is less than this distance threshold value, object 11 is still in the close range of ultrasonic sensor 1 and ultrasonic sensor 1 continues with the eighth step 1007 . If this detected distance is greater than this distance threshold value, then object 11 is no longer in the close range of ultrasonic sensor 1 and ultrasonic sensor 1 continues with first step 1000 . If the first step 1000 corresponds to the eighth step 1007 and the ultrasonic sensor 1 determines a first time difference 101 in the eighth step 1007, the ultrasonic sensor 1 can also continue with the second step 1001 directly.

1. i. Verwenden von ausgesendeten Ultraschallbursts 10 einer ersten zeitlichen Länge für Ultraschallhauptmessungen 505, sofern sich kein Objekt 11 im Nahbereich des Ultraschallsensors 1 aufhält, und Erfassen des Vorhandenseins eines Objekts 11 im Nahbereich des Ultraschalsensors 1 sofern das Objekt 11 sich dort befindet.
2. ii. Verkürzen der ersten zeitlichen Länge der ausgesendeten Ultraschallbursts 10 zu einer zweiten zeitlichen Länge der ausgesendeten Ultraschallbursts 10 und Erfassen eines Abstands zwischen Ultraschallsensor 1 und Objekt 11 für die Dauer des Aufenthalts des Objekts 11 im Nahbereich des Ultraschallsensors 1.

The procedure of 13 and 14 can then be summarized like this:

1. i. Use of transmitted ultrasonic bursts 10 of a first temporal length for main ultrasonic measurements 505, provided that there is no object 11 in the vicinity of ultrasonic sensor 1, and detecting the presence of an object 11 in the vicinity of ultrasonic sensor 1 if object 11 is there.
2. ii. Shortening the first length of time of the transmitted ultrasonic bursts 10 to a second length of the transmitted ultrasonic bursts 10 and detecting a distance between the ultrasonic sensor 1 and the object 11 for the duration of the stay of the object 11 in the vicinity of the ultrasonic sensor 1.

Miscellaneous

The above description is not exhaustive and does not limit this disclosure to the examples shown. Other variations to the disclosed examples may be understood and practiced by those of ordinary skill in the art given the drawings, disclosure, and claims. The indefinite article "a" or "an" and its inflections do not exclude a plurality, while the mention of a definite number of elements does not exclude the possibility of there being more or fewer elements. A single entity may perform the functions of multiple elements recited in the disclosure, and conversely, multiple elements may perform the function of one entity. Numerous alternatives, equivalents, variations Functions and combinations are possible without departing from the scope of the present disclosure.
Unless otherwise stated, all features of the present invention can be freely combined with one another. This applies to the entire document presented here. Also the one in the
The features described in the description of the figures can, unless otherwise stated, be freely combined with the other features as features of the invention. A limitation of individual features of the exemplary embodiments to the combination with other features of the exemplary embodiments is expressly not intended. In addition, physical features of the device can also be reworded as method features and method features can be reworded as physical features of the device. Such a reformulation is thus automatically disclosed.
In the foregoing detailed description, reference is made to the accompanying drawings. The examples in the specification and drawings should be considered as illustrative and not limiting on the specific example or element described. Several examples can be derived from the foregoing description and/or the drawings and/or the claims by modifying, combining or varying certain elements. Furthermore, examples or elements that are not literally described can be derived from the description and/or the drawings by a person skilled in the art.

Reference List

1

ultrasonic sensor;

2

Computer core of the ultrasonic sensor 1;

3

digital ultrasonic burst generation of the ultrasonic sensor 1;

4

Control signals for the digital ultrasonic burst generation 3 of the ultrasonic sensor 1;

5

digital ultrasonic transmission signal;

6

analog ultrasonic transmission stage of the ultrasonic sensor 1;

7

Control signal of the ultrasonic sensor 1;

8th

vibrating element 8 of the ultrasonic transducer 9;

9

ultrasonic transducer 9;

10

transmitted ultrasonic burst;

11

objects 11 in the vicinity of the vehicle;

12

reflected ultrasonic burst;

13

electrical ultrasound reception signal;

14

Amplifier;

15

amplified electrical ultrasound reception signal;

16

analog-to-digital converter of the ultrasonic sensor 1;

17

digitized ultrasound reception signal;

18

digital processing and filter stage;

19

filtered ultrasound reception signal;

20

data bus;

21

Control unit 21 of the ultrasonic sensor system 22;

22

ultrasonic sensor system;

23

first comparator;

24

first threshold signal;

25

first comparator output signal;

26

second comparator. In 4 a second comparison logic replaces the second comparator. The second comparison logic is a digital, functionally equivalent counterpart of the second comparator. The second comparator compares the second threshold value of the second threshold value signal 27 with the value of the amplified electrical ultrasound reception signal 15. The analog-to-digital converter 16 is arranged after the amplified electrical ultrasound reception signal 15 in the signal path. (see also 1 ). The functionally equivalent second comparison logic compares the second threshold value of the second threshold value signal 27 with the value of the processed, digital ultrasonic received signal 34, which is preferably the envelope signal or includes it. In this case, the analog-to-digital converter 16 is arranged in front of the conditioned, digital ultrasonic received signal 34 in the signal path. (see also 4 );

27

second threshold signal;

28

second comparator output signal;

29

threshold generating device;

30

EXOR link;

31

output of EXOR gate 30;

32

EXOR control signal;

33

envelope filter;

34

processed, digital ultrasonic received signal, which is preferably the envelope signal or includes;

35

digital part;

36

analog part;

37

evaluation circuit;

38

positive supply voltage line;

39

voltage regulator;

40

negative supply voltage line;

41

timer;

101

first time difference between the first time 102 of the first edge change of the first comparator output signal 25 and the subsequent second time 103 of the second edge change of the second comparator output signal 28;

102

first point in time 102 of the first edge change of the first comparator output signal 25;

103

second point in time 103 of the second edge change of the second comparator output signal 28;

105

second threshold 105 of the second threshold signal 27;

106

Amplitude 106 of the envelope signal, here as an example in LSB of the analog-to-digital converter 16. In the case of 1 it is the envelope signal of the amplified electrical ultrasound reception signal 15. In the case of 4 it is the envelope signal of the processed, digital ultrasonic received signal 34;

107

Amplitude of the envelope signal. In the case of 1 it is the envelope signal of the amplified electrical ultrasound reception signal 15. In the case of 4 it is the envelope signal of the processed, digital ultrasonic received signal 34;

108

Overdrive by the amplitude curve 107 of the envelope signal;

501

second time difference between the third point in time of the third edge change 502 of the first comparator output signal 25 and the subsequent fourth point in time of the fourth edge change 503 of the second comparator output signal 28;

502

third point in time of the third edge change of the first comparator output signal 25;

503

fourth point in time of the fourth edge change of the second comparator output signal 28;

504

first ultrasound envelope signal (example compensation measurement);

505

second ultrasound envelope signal (example main ultrasound measurement);

506

transmission period;

507

number of sampling times of the analog-to-digital converter 16;

900

first step;

901

second step;

902

Third step;

903

fourth step;

904

fifth step;

905

sixth step;

906

seventh step;

1000

first step;

1001

second step;

1002

Third step;

1003

fourth step;

1004

fifth step;

1005

sixth step;

1006

seventh step;

1007

eighth step;

1008

ninth step;

SdT

State of the art;

T

temperature in °C;

t

Time;

Claims (1)

Ultrasonic measuring system (22) for environment detection devices, wherein the ultrasonic measuring system comprises an ultrasonic sensor (1) and wherein the ultrasonic sensor (1) has a close range in which it can no longer detect the distance from the ultrasonic sensor (1) to objects (11) with emitted ultrasonic bursts 10 of a first temporal length, wherein the ultrasonic sensor (1) at least temporarily generates an ultrasonic burst (10 ) emits a first length of time for an ultrasonic main measurement (505), provided that there is no object (11) in the vicinity of the ultrasonic sensor (1), and wherein the ultrasonic sensor (1) detects the presence of an object (11) in the vicinity of the ultrasonic sensor (1) detects if the object (11) is located there and the ultrasonic sensor (1) for the duration of the presence of the object (11) in the vicinity of the ultrasonic sensor (1) the first temporal length of the transmitted ultrasonic bursts (10) at a second temporal length of the emitted ultrasonic bursts (10) and wherein the ultrasonic sensor (1) detects a distance between the ultrasonic sensor (1) and the object (11) for the duration of the stay of the object (11) in the vicinity of the ultrasonic sensor (1) and wherein the ultrasonic sensor (1) after the end of the stay of the object (11) in the vicinity of the ultrasonic sensor (1), the second length of time of the emitted ultrasonic bursts (10) is extended to a third length of time of the emitted ultrasonic bursts (10), and the third length of time of the emitted ultrasonic bursts (10 ) can be the same as the second temporal length of the transmitted ultrasonic bursts (10).

Images