Device for environmental sensing with improved dynamic adaptation

Abstract

Device (1) for environmental sensing, comprising: - a signal converter (2), - a receiving path (C1, R1, R2, 4) directly connected to the signal converter (2) for transmitting signals received via the signal converter (2) to an evaluation unit (6), and - a transformer (5), wherein the device is configured: - in a first time range, to supply the signals originating from the signal converter (2) to the evaluation unit (6) by means of the transformer (5) with a first voltage level, - in a second time range, to supply the signals originating from the signal converter (2) to the evaluation unit (6) with a second voltage level.

Description

State of the art

[0001] The present invention relates to a device for environmental sensing, such as could be used for distance measurements in vehicles. In particular, the present invention relates to improvements in the processing of converter signals with different dynamic ranges.

[0002] In acoustic environment detection, electro-acoustic transducers (e.g., ultrasonic transducers) are frequently used both to transmit acoustic measurement signals and to receive reflected acoustic measurement signals. Due to the high internal resistance of the transducers used, a transformer is typically employed to generate an electrical transmission signal with an amplitude of more than 100 V from the available supply voltage (e.g., from a vehicle's electrical system), which is typically 8 V to 24 V. Fig. Figure 1 shows such a device setup.1 With a power output stage 3 This is done in at least one coil L1 of a transformer. 5 A strong alternating current is applied. The coil L2 is on the opposite side of the transformer. 5 It has more windings, which is why the impressed alternating current signal enters the electro-acoustic transducer at a higher voltage. 2 is imprinted. As a result, it emits an acoustic signal into the environment. Acoustic signals, such as echoes resulting from the emitted acoustic measurement signal and / or from emissions from other acoustic signal sources, are transmitted to the electro-acoustic transducer. 2 Upon arrival, the signals typically generate a received signal with an amplitude that is an order of magnitude smaller. This signal is amplified by components C1, R1, R2, and an operational amplifier in the receive path. 4 reinforced and a subsequent evaluation unit 6provided. For cost reasons, the components of the area shown to the right of the vertical dashed line are preferably combined in an integrated circuit, which is connected to the components shown to the left of the dashed line via three to four pins P (shown as circles). Fig. Figure 1 shows only the function of the essential components. It is known to those skilled in the art that the integrated circuit (IC) is usually also connected to the system ground and the supply voltage, and that the system ground and supply voltage typically represent a short circuit for AC voltage signals, such as those used in devices of this type. At the electro-acoustic transducer 2 Incoming echoes, especially at the beginning of the echo cycle, overlap with the decay signals of the electro-acoustic transducer. 2While the transducer's decay signals can exhibit voltages of approximately 100V and higher, the signal strength at the end of an echo cycle is around 1 microvolt. Evaluating both signals is desirable because, in addition to the environmental sensors that analyze the echo signals, the decay signals also provide relevant information for verifying the transducer's functionality. With the increasing integration of acoustic sensors into safety-critical system functions, it is becoming ever more important to be able to detect and assess safety-relevant sensor degradation and failures by analyzing the decay signal.

[0003] DE 10 2009 027 842 describes the detection of transducer degradation due to dirt or other deposits using the decay signal. For this purpose, the instantaneous frequency and its variation are determined and evaluated from intrapulse information. The basic principle of acoustic environment detection is to infer the presence of reflective objects from changes in frequency, phase, and signal strength.

[0004] DE 101 36 628 A1 describes a method and a device for operating an ultrasonic transducer, wherein a transmit signal is generated from a lower supply voltage using a transformer, and wherein a secondary coil of the transformer is decoupled from a receiving circuit of the ultrasonic transducer. An antiparallel oriented pair of diodes is proposed for decoupling.

[0005] DE 25 51 979 discloses an ultrasonic transceiver device in which a switching element with a transformer is provided, the primary winding of which is connected in parallel to the ultrasonic transceiver of the ultrasonic generator, while diodes are connected to each end of the secondary winding. A reflected signal passes through the open diodes and reaches the secondary winding of the transformer, which is connected to an amplifier. The amplifier is protected during transmission by the diodes and a control signal.

[0006] DE 198 36 997 A1 discloses a receiver circuit whose purpose is to eliminate the need for expensive components such as separate control lines or transformers (with multiple windings and taps).

[0007] It is an object of the present invention to be able to perform an analysis of a generic system with regard to its oscillation behavior with the least possible hardware effort. Disclosure of the invention

[0008] The aforementioned problem is solved according to the invention by a device for environmental sensing. This device comprises a signal converter, which can be configured, for example, as an electro-acoustic converter, preferably as an ultrasonic converter. A receiver path for transmitting signals received via the signal converter to an evaluation unit is connected to the signal converter. The receiver path can be configured to amplify the converter signals. In particular, signal strength-dependent amplification and / or time-of-flight-dependent amplification can be provided to ensure that the evaluation unit is always supplied with suitable signal levels. The device also includes a transformer configured to convert the signals originating from the signal converter (oscillation signals and / or received signals) at least in a first time domain and supply them to the evaluation unit. The transformer can be part of a transmit path of the device.In a second time domain, the device is configured to supply the signals originating from the signal converter to the evaluation unit at a second voltage level. For this purpose, the transformer's transfer characteristics can be adjusted or it can be bypassed entirely. The transformer can be used to adapt significantly different voltage levels to the dynamic range of the evaluation unit's input. In this way, the same evaluation unit can be used for both analyzing the decay signal to verify the converter's functionality and analyzing received echoes to detect environmental objects. This offers the advantage that the evaluation unit itself can have a smaller dynamic range at its inputs, thus enabling the use of more cost-effective hardware.

[0009] The dependent claims describe preferred embodiments of the invention.

[0010] Furthermore, the device can be configured to supply an electrical signal, impressed on a first side of the transformer via a transmission path (e.g., comprising a transmitting amplifier), to the signal converter on a second (opposite) side of the transformer. In other words, the transformer is used to increase the output voltage of the transmitting amplifier during transmission and supply it to the signal converter. According to the invention, the same transformer can now be used to convert the signals from the signal converter to a lower voltage level and to evaluate them with the evaluation unit. This reduces the hardware requirements for implementing the present invention.

[0011] Preferably, the device can be configured to measure a current and / or a voltage, and in particular, a phase relationship between the current and the voltage. The aforementioned quantities can be converted from the signal converter to a voltage level suitable for signal evaluation via the transformer. For this purpose, they are supplied to the evaluation unit via the transformer. A shunt can be provided on the low-voltage side of the transformer, particularly for current measurement. The shunt can, for example, be included in a transmitting circuit that comprises an inductor of the transformer with the lower number of turns and a transmitting output stage.In other words, the transmitting circuit can consist of the power supply with its two terminals, "positive potential and ground," the inductor transformer with the fewer number of turns, and a transistor representing the transmitting output stage, with the main current flowing from the collector to the emitter. Additionally, the shunt resistor for current measurement can be connected to ground. In this way, the high levels during excitation and decay of the transducer diaphragm, as well as received echoes, can be adapted to the subsequent evaluation unit.

[0012] Preferably, the device can include a switching device by means of which an output signal of the signal converter, transformed by the transformer, and / or an output signal of the receiving path or the receiving amplifier can be selected and fed to the evaluation unit. A partial selection of both signals is also possible, provided that the switching device feeds the aforementioned signals to the evaluation unit with a time offset from each other or transmits them simultaneously with optional level adjustment. This offers the advantage that only suitable signal levels are fed to the evaluation unit, depending on the current operating state.

[0013] The switching device can, for example, be configured to be triggered at a predefined point in the transmission cycle and / or when the signal level falls below a predefined threshold. The aforementioned conditions can thus be understood and applied as a predefined switching threshold. They represent a suitable way to process the signal level at the signal converter for evaluation.

[0014] Preferably, a nonlinear two-terminal network can be provided between the transformer and the signal converter. This two-terminal network can, for example, comprise two diodes connected in antiparallel to each other, connected on one side to the inductance of the transformer, which has the higher number of turns, and on the other side to electrical ground. At high signal levels, such as those occurring during transmission or the early phase of decay, the nonlinear two-terminal network is conductive, allowing the transmission process to proceed essentially unimpeded. Additionally, signals intended for evaluation at high levels are fed to the evaluation unit via the transformer, while signal levels below the blocking voltage of the nonlinear two-terminal network are fed to the evaluation unit exclusively via the receive path.This represents a circuit-technically simple, cost-effective and safe way to control the level-dependent signal routing.

[0015] Alternatively or additionally, an adder can be provided, which is configured to supply an output signal from the receiving path and a converter signal, transformed via the transformer, to the evaluation unit. In this way, a level-dependent switching process can be avoided.

[0016] If a transmitting amplifier is also included in the device according to the invention, its output can be electrically connected to, or be electrically connected to, the transformer inductance with the fewer number of turns. In this way, a suitable transmit signal can be generated at lower levels at the transmitting amplifier output without requiring an additional transformer to implement the present invention. In particular, the evaluation unit can also be part of the device and / or comprise an integrated circuit, wherein the transmitting amplifier is also arranged in the same integrated circuit. Depending on the design of any feedback branch in the receive path, the part of the integrated circuit intended for converter coupling can be implemented with only three or four pins, which reduces manufacturing costs.

[0017] The evaluation unit can be further configured to analyze a signal originating from the signal converter even during transmission, particularly during the oscillation of a diaphragm within the converter. Additionally, the evaluation unit can be configured to analyze echoes received from the environment and identify environmental objects within the converter signal. Accordingly, all analysis in conjunction with environmental detection can be performed by a single evaluation unit, which also only needs to be able to process a limited dynamic range at its input. Brief description of the drawings

[0018] Exemplary embodiments of the invention are described in detail below with reference to the accompanying drawings. The drawings show:

[0019] Fig. 1 an example of a generic device for environmental sensing;

[0020] Fig. 2 a first embodiment of a device according to the invention for environmental sensing;

[0021] Fig. 3 a second embodiment of a device according to the invention for environmental sensing;

[0022] Fig. 4 a third embodiment of a device according to the invention for environmental sensing; and

[0023] Fig. 5 a fourth embodiment of a device according to the invention for environmental sensing. Embodiments of the invention

[0024] Fig. Figure 1 shows a schematic representation of a device 1 For environmental sensors. An ultrasonic transducer. 2 It is set up as a signal converter for ultrasound signals. 11 to send and receive. For this purpose, the ultrasound transducer is used. 2 on the one hand via a transformer comprising the inductors L1, L2 5 to a transmitter amplifier 3connected to a transmitter. On the other hand, the ultrasound transducer 2 via a first capacitor C1 and an ohmic resistor R1 connected in series with it to the input of a receiving amplifier 4 connected to a receiving path. The receiving amplifier 4 The signal is fed back via a second ohmic resistor R2. At the output of the receiver amplifier. 4 is an evaluation unit 6 connected. Along a dashed line, four pins P1, P2, P3, and P4 are shown, which represent inputs and outputs of an integrated circuit located to the right of the dashed line. Via the transformer 5 is the device 1 set up, which are powered by the transmitter amplifier 3 to transform the generated signals to a higher voltage level in order to achieve transmission levels of at least 100V for emission by the ultrasonic transducer 2to be able to provide it. Further use of the transformer 5 This is not the case, as all reception processes take place via the reception path and the reception amplifier. 4 take place.

[0025] Fig. Figure 2 shows a modification according to the invention of the in Fig. 1 device shown 1 This also has a signal path. 7 on, which is the first inductance L1 of the transformer 5 with the evaluation unit 6 connects. From the ultrasound transducer 2 Received signals can therefore be passed through the transformer 5 converted to a lower voltage level and then sent to the evaluation unit 6 be supplied. In the evaluation unit 6 In this way, for example, sensor degradation can be detected, which is reflected in the transmit and decay signal of the membrane of the ultrasound transducer. 2 find again.

[0026] Fig. Figure 3 shows an alternative embodiment of the device according to the invention. 1 , which differs from the in Fig. 2 device shown 1 through a switching device 8 differentiates. By means of the switching device 8 can the evaluation unit 6 optionally, via the receiver amplifier 4 or one via the transformer 5 a converted received signal is fed in. Furthermore, it shows Fig. 3 a variant of the electrical circuit of the first inductance L1 of the transformer and the transmitting amplifier 3 . In the in Fig. In the arrangement shown in 3, the inductor L1 is connected to electrical ground at one terminal, while in the one shown in Fig. In the arrangement shown in section 2, the first inductor L1 is connected to both terminals of the transmitting amplifier. 3 is connected.

[0027] Fig. Figure 4 shows further variations in the form of another embodiment of a device according to the invention. 1 The in Fig. 3 shown switching device 8 is through an adder 9 It has been replaced. In this way, switching operations can be avoided and determining a suitable switching point is unnecessary. In addition, the second inductance L2 of the transformer is 5 one-sided via a non-linear two-terminal network 10 connected to electrical ground. The nonlinear two-terminal network 10 It comprises two diodes D1 and D2 connected in antiparallel. At low voltages below the forward voltage of diodes D1 and D2, no current flows through the second inductor L2. However, at voltages above the forward voltage, diodes D1 and D2 conduct the electric current, so that the ultrasonic transducer 2 received signals via the transformer 5converted and the evaluation unit 6 are supplied. In this way, the dynamic range of signals that are within the integrated circuit (to the right of the vertical dashed line) or from the evaluation unit is increased. 6 The number of processes required is significantly increased. This occurs as the diaphragm of the ultrasonic transducer continues to oscillate. 2 Voltage levels are set at the output of the ultrasound transducer. 2 one which, without such a downconversion, goes directly via the receive path or the receive amplifier 4 the evaluation unit 6 can be supplied without overriding it.

[0028] Fig. Figure 5 shows a further embodiment of a device according to the invention. 1 , in which the transmitter, including the transmitter amplifier 3 , via the additional reception path 7a , 7b in an alternative way with the evaluation unit 6and is connected to the first inductor L1. The transmitting circuit consists of a voltage supply UB, the coil L2, a transistor T representing the transmitting output stage, and the shunt resistor R3 to ground, with the main current flowing through the collector to the emitter of transistor T. The output of the transmitting amplifier 3 is connected to the base of transistor T, whose collector has a first part 7a of the additional reception path 7 with the first inductor L1 and the switching device 8 The emitter of transistor T is connected to ground via a third ohmic resistor R3. Additionally, the emitter is connected via a second part. 7b of the additional reception path 7 electrically connected to the evaluation unit 6A second terminal of the first inductor L1 is connected to a supply voltage UB. The illustrated arrangement allows current measurement during transmission. The voltage across resistor R3 at the emitter of transistor T is a measure of the transmission current. The phase of the transmission voltage coupled into transistor T is usually known to the controller (not shown). The state of the ultrasonic transducer can be determined solely from the phase relationship of the transmission current to the phase relationship of the transmission voltage. 2 or infer from reflective objects in its vicinity. It is known to those skilled in the art that there are other, and in particular more complex, ways of designing transmitter amplifiers. 3There are, for example, push-pull output stages and A / AB operation. Particularly with output stages that do not operate solely in switching mode, it is possible to determine not only the transmit current but also a measure of the simultaneously occurring transmit voltage. This allows for a more precise determination of the transducer's state and the reflective objects located in its immediate vicinity. Thus, the efficiency of transmission using the ultrasonic transducer can be calculated from the ratio of transmit current to transmit voltage. 2 can be determined. Additionally, for objects with known reflectivity, the behavior of the received signals when the objects move in front of the ultrasound transducer can be used to determine their reflectivity. 2 especially on the system efficiency of the ultrasound transducer 2and / or conclusions can be drawn from the attenuation profile in the medium (e.g., air). For possibilities of evaluating the received signals, reference is made to DE 10 2009 054 667 A1. In alternative configurations, the boundary between the integrated circuit (IC, to the right of the vertically dashed line in the figures) and its external circuitry can be defined differently. For example, the evaluation circuit can be 6 can be implemented externally or within the integrated circuit. Furthermore, it should be noted that the application of the present invention is not limited exclusively to the ultrasound range, even though the exemplary embodiments described above have been described using ultrasound signals. For example, similar embodiments can also be used in the audible range. Moreover, it is evident that the Fig. 2 to Fig.The five described variants represent a selection of possible combinations to functionally illustrate the lessons of the circuits shown therein. Alternative combinations of the variants are, of course, possible without departing from the scope of the present invention, the scope of which is defined by the appended claims. QUOTES INCLUDED IN THE DESCRIPTION

[0029] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0030] DE 102009027842

[0003] DE 10136628 A1

[0004] DE 2551979

[0005] DE 19836997 A1

[0006] DE 102009054667 A1

[0028]

Claims

[1] Device ( 1 ) for environmental sensors, comprehensive – a signal converter ( 2 ), – one directly on the signal converter ( 2 ) connected receive path (C1, R1, R2, 4 ) for transmission via the signal converter ( 2 ) received signals to an evaluation unit ( 6 ), and – a transformer ( 5 ), where the device is set up, – in a first time range, the signal converter ( 2 ) signals originating from the transformer ( 5 ) with a first voltage level of the evaluation unit ( 6 ) to supply, – in a second time domain, the signal converter ( 2 ) originating signals with a second voltage level from the evaluation unit ( 6 to supply. [2] Device according to claim 1, wherein the device ( 1 ) is further set up, a transmission path (3 ) on a first side of the transformer ( 5 ) Imprinted electrical signal on a second side of the transformer ( 5 ) the signal converter ( 2 to supply. [3] Device according to claim 1 or 2, which is configured to measure a current and / or a voltage, in particular also a phase relationship existing between the current and the voltage, which is measured by the signal converter ( 2 ) originating via the transformer ( 5 ) are converted, in particular using a shunt (R3) for current measurement. [4] Device according to one of the preceding claims further comprising a switching device ( 8 ) to select one using the transformer ( 5 ) converted output signal of the signal converter ( 2 ) and / or to convert an output signal of the receive path (C1, R1, R2, 4 ). [5] Device according to one of the preceding claims, wherein the switching device ( 8 ) is set up, in response to – a predefined time in the transmission cycle and / or – a drop below a predefined signal level instead of using the transformer ( 5 ) converted output signal the output signal of the receiving path (C1, R1, R2, 4 to convert. [6] Device according to one of the preceding claims, wherein between the transformer ( 5 ) and the signal converter ( 2 ) a nonlinear two-terminal network ( 10 ) is provided, which in particular includes two antiparallel connected diodes (D1, D2). [7] Device according to one of the preceding claims, further comprising an adder ( 8 ), which is set up to provide an output signal from the receiving path (C1, R1, R2, 4 ) and one on a first side of the transformer ( 5) incoming signal from an evaluation unit ( 6 to supply. [8] Device according to one of the preceding claims, wherein the transformer ( 5 ) is further set up, an output signal from the transmitting amplifier ( 3 ) to convert to a higher voltage level and to the signal converter ( 2 to supply. [9] Device according to one of the preceding claims, wherein the evaluation unit ( 6 ) Part of the device ( 1 ) is and / or comprises an integrated circuit, in particular including the transmitting amplifier ( 3 ) is contained in the integrated circuit. [10] Device according to one of the preceding claims, wherein the evaluation unit ( 6 ) is set up during a transmission process and / or during a oscillation of a diaphragm of the signal converter ( 2 ) a signal converter ( 2 to analyze the signal originating from the source. [11] Device according to one of the preceding claims, wherein the device ( 1 ) for environmental sensors for an automotive application and the signal converter ( 2 ) is designed as an ultrasound transducer.

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