DE102016103690B3 - Optical transit time measurement according to a one- or two-stage delta-sigma method - Google Patents

Abstract

The invention relates to a method and an associated apparatus for determining the transit time for a first optical signal (s1) in a first transmission path (I1) between a transmitter (H) and a first receiver (D1). The transmitter (H) transmits a first signal (s1) into the first transmission path (I1) which after passage (and therefore delay) through at least a part of the first transmission path (I1) from the first receiver (D1) as a second signal ( s2), which is a modified first signal (s1), is received and converted into a receiver output signal (S0). In the first receiver (D1), the second signal (s2) is evaluated in two reception windows, a first reception window (SF1) with a first time length (T1) and a second reception window (SF2) with a second time length (T2) , In this case, the beginning of the first signal (s1) is contained exclusively in the first reception window (SF1) and the end of the first signal (s1) exclusively in the second reception window (SF2). The receiver output signal (S0) comprises a first signal component to be assigned to the first reception window (SF1) and a second signal component to be assigned to the second reception window (SF2). In this case, the first signal component averaged over a predefined period of time (Tz) is just as large as the second signal component averaged over the time segment (Tz), except for a deviation which is preferably used as a controlled variable. The deviation is at least temporarily determined as a control signal for the temporal position of one or both receiving windows (SF1, SF2) in relation to the first signal (s1) and / or the temporal position of the first signal (s1) in relation to the two receiving windows (SF1, SF2). SF2), and / or the first time length (T1) of the first reception window and / or the second time length (T2) of the second reception window (SF1, SF2).

Description

introduction

The measurement of the light transit time is a common method for distance measurement by means of modulated light signals. Known solutions have limitations in the external light suppression, high demands on the analog components and therefore require complex and expensive architectures and cause a high power consumption.

Various devices for measuring light intensity and measuring the time of flight are known from the prior art. Here are, for example:
DE 19 833 207 A1 . DE 10 2009 020 218 B3 . EP 1 678 523 B1 . DE 10 2011 076 635 B3 . DE 10 2012 206 089 A1 . DE 10 2009 037 596 A1 . DE 10 2008 018 718 A1 . WO 2007 031 102 A1 . EP 1 048 961 B1 . DE 10 138 531 A1 . DE 10 2007 046 562 A1 . DE 10 163 534 A1 . DE 10 221 578 A1 . US 2007 0 181 786 A1 . DE 10 2007 023 920 A1 ,

• 1) Die Auflösungserhöhung über die Diskretisierung des DACs (DLL) hinaus erfolgt nur über eine Mittelung nach der Diskretisierung nicht über eine Delta-Sigma-Regelschleife, weil die dafür bestimmende Information – der analoge Restfehler nach der Diskretisierung – gelöscht wird;
• 2) Die Regelschleife regelt nur über den bereits diskretisierten (digitalen) Fehler, sodass die Regelung nur mit einem Mindestrauschen funktioniert;
• 3) Die Verfahren erfordern ein hohe Schaltungskomplexität der entsprechenden Vorrichtungen;
• 4) Es bestehen extreme Anforderungen an die Amplitudenregelung;
• 5) Es tritt ein hoher Stromverbrauch auf;
• 6) Es entstehen starke Lastwechsel;
• 7) Es entstehen hohe Stromspitzen im Falle eines Burst-Betriebs;
• 8) Es besteht die Notwendigkeit einer optisch komplex angekoppelten Kompensator LED;
• 9) Ein Parallelbetrieb mehrerer Fotodioden ist nicht möglich.

From the WO 2013/083 346 A1 is a Halios delta-sigma system for distance measurement known. From the WO 2007 012 501 A1 is a Halios delay solution with temporally unregulated analysis signals (reference characters A, B, C, D of the WO 2007 012 501 A1 ) known. This solution of HALIOS ^® -TOF sensor technology has the following disadvantages:

• 1) The resolution increase beyond the discretization of the DAC (DLL) is done only via averaging after the discretization via a delta-sigma control loop, because the information that determines it - the analog residual error after discretization - is deleted;
• 2) The control loop only controls over the already discretized (digital) error, so that the control works only with a minimum noise;
• 3) The methods require high circuit complexity of the respective devices;
• 4) There are extreme requirements for the amplitude control;
• 5) There is a high power consumption;
• 6) There are strong load changes;
• 7) High current peaks occur in the event of a burst operation;
• 8) There is a need for an optically complex coupled compensator LED;
• 9) Parallel operation of several photodiodes is not possible.

The thus defined system performance is accordingly insufficient for many commercial applications. This leads to too high system complexity, which in turn has too large a chip area in the case of monolithic integrated circuits and thus too high current consumption result. In addition, these techniques are not sufficiently scalable so that multiple TOF channels can not be readily operated in parallel with a single transmit channel.

From the DE 101 53 742 A1 a device for determining the transit time of a first transmission link between a transmitter and a receiver is known. During operation of the device, the emitted laser pulse is shifted relative to the integration time Ti by discrete delay increments. As a result, the received pulse moves with increasing delay of the respective transmit pulse from left to right through the two receiving windows. The difference between the portions of the receive signal integrated in both receive windows is a monotone function of the steep zero crossing delay time. The delay time corresponding to the zero crossing is determined by means of an interpolation method and not exactly determined, which represents a first disadvantage of this method. The distance to the surface element corresponding to the respective receiving pixel in the 3D scene is then determined from the delay time thus interpolated. The positioning of the receiving window is controlled in a given grid and not in response to the received signal and only with a given granularity.

From the WO 02/025805 A2 is a regulated transit time known.

Object of the invention

It is the object of the invention to provide a method which does not have the above-described disadvantages in the prior art to that extent or not.

This object is achieved by a method according to claim 1

Description of the invention

• 1. Das Zurücksetzen des Integrators nach jedem Integrationszeitfenster, wie heute bekannt, wird eliminiert.
• 2. Die Differenz der Integrale auf steigender und fallender Flanke des Senderpulses wird schon im Speicherelement des Integrators gebildet. Hierzu benötigt man einen Mechanismus der die Integration mit wählbarem Vorzeichen ermöglicht.
• 3. Die Rückkoppelung vom Diskretisierer zum DAC erfolgt unmittelbar zu dem nächsten Mess-Puls.
• 4. Der Tiefpass, welcher das Ergebnis ermittelt, wird außerhalb der Regelschleife realisiert.

To improve the state of the art, the zero regulation of the phase is modified to a delta-sigma method. This is achieved by the following technical measures:

• 1. The resetting of the integrator after each integration time window, as known today, is eliminated.
• 2. The difference of the integrals on rising and falling edge of the transmitter pulse is already formed in the memory element of the integrator. This requires a mechanism that allows integration with selectable sign.
• 3. The feedback from the discretizer to the DAC takes place immediately at the next measurement pulse.
• 4. The low pass which determines the result is realized outside the control loop.

Another independent point is the zero control of the phase by shifting the integration window instead of shifting the transmit signal in time. This achieves scalability. This means that several sensor channels can be simultaneously subjected to a zero control with an LED signal.

The invention thus relates to a method for determining the transit time in a first transmission path (I1) between a transmitter (H) and a first receiver (D1). In order to feed the transmitter (H), a transmission signal (S5d) delayed by a delay time (Δt) is formed either by means of a delay unit (ΔT) from a transmission signal (S5), or the transmission signal (S5) is used as a delayed transmission signal (S5) at least temporarily. S5d), which in the sense of this disclosure always feeds the transmitter (H). The transmitter (H) now sends in response to the said delayed transmission signal (S5d) a first, in particular optical, signal (s1) in terms of time in relation to a time period (T _z ) in the first transmission path (I1). The first signal (s1) in this case has at least one carrier signal as a signal component, which is modulated at least with a modulation signal in the amplitude and / or phase and / or polarization and / or wavelength and / or amplitude modulation frequency and / or the spectral composition. For example, it is a light signal that is emitted by an LED amplitude modulated with a modulation frequency and a predetermined optical wavelength. Most preferably, it is a pulsed laser diode. In each time interval (T _z ) in which the transmitter (H) transmits the first signal (s1), the first signal (s1) within this relevant time period (T _z ) has a first time start (t _s1 ) and a first time End (t _e1 ). In the sense of a pulsed operation, the beginning of the pulse is to be understood as the first temporal beginning (t _s1 ) and the end of the transmission pulse is meant by the first temporal end (t _e1 ). The time slots (T _z ) are preferably but not necessarily of the same length in time. Each time gate (T _z ) has a time start (t _sz ) of the time period (T _z ) and a time end (t _ez ) of the time period (T _z ). Also, the first temporal beginning (t _s1 ) and the first temporal end (t _e1 ) of the first signal (s1) are preferably but not necessarily the same from one period to the next. In the following, we consider only a single period of time (T _z ), with the preceding periods (T _z ) and the following periods (T _z ) behaving similarly. The time segments (T _z ) preferably do not overlap and do not necessarily follow each other directly. Rather, it is conceivable that periods of time are separated from each other by larger time intervals.

The first transmission path (I1) preferably contains an object (O) whose distance is to be determined by the transit time measurement. Of course, the transit time in the first transmission path (I1) itself can also be determined in order to determine, for example, the refractive index in the transmission path. The first transmission path (I1) thus modifies the first signal (s1) when passing through this first transmission path (I1) to a second, in particular optical, signal (s2). So here we take the object (O) as part of the first transmission link (I1). This modification may relate to the amplitude and / or the phase and / or the polarization and / or the wavelength and / or the amplitude modulation frequency and / or the spectral composition of the second signal (s2) compared to the first signal (s1) corresponds to the phase of a delay through the term. After the first signal (s1) has passed through the first transmission path (I1) and has been modified to the second signal (s2), the first receiver (D1) receives the second signal (s2) after leaving the first transmission path (I1) within this relevant period of time (T _z ). In the first receiver (D1), the second signal (s2) is converted into a receiver output signal (S0) by it. A first multiplier (M1) multiplies the receiver output signal (S0) by a first receiving window signal (SF1) to a first internal signal (S2a) within this relevant time period (T _z ). The first receive window signal (SF1) has a second time start (t _s2 ) within the relevant time segment (T _z ) which occurs before the first time start (t _s1 ) of the first signal (s1) and before the end of time ( t _e1 ) of the first signal (s1) is located. On the other hand, the first receive window signal (SF1) has a second time end (t _e2 ) within the relevant time segment (T _z ), which is temporally after the first time start (t _s1 ) of the first signal (s1) and temporally before the time end (t _e1 ) of the first signal (s1) is located.

The first reception window, which is defined by the first reception window signal (SF1), is thus such that it overlaps with the transmission pulse of the first signal (s1) in such a way that the transmission pulse starts in the first reception window and the first reception window ends before the reception signal Send pulse ends.

A second multiplier (M2) multiplies the receiver output signal (S0) by a second receive window signal (SF2) to a second one within this respective time period (T _z ) internal signal (S2b). The second receive window signal (SF2) has a third time start (t _s3 ) within the relevant time segment (T _z ) which occurs after the first time start (t _s1 ) of the first signal (s1) and before the end of time ( t _e1 ) of the first signal (s1) is located. The second receive window signal (SF2) has a third time end (t _e3 ) within the relevant time segment (T _z ) which occurs after the first time start (t _s1 ) of the first signal (s1) and after the end of time ( t _e1 ) of the first signal (s1) is located.

The second reception window, which is defined by the second reception window signal (SF2), is thus such that it overlaps with the transmission pulse of the first signal (s1) such that the transmission pulse stops in the second reception window and the second reception window ends after the transmission pulse ,

The two signals thus formed are now processed further. A first filter (F1) now forms, within this relevant time segment (T _z ), the difference between the previously formed first internal signal (S2a) and the second internal signal (S2b). The result of the filtering by the first filter (F1) is a first filter output signal (S8). Very preferred is an integration and / or low-pass filtering by the first filter (F1).

In a first variant, the second time start (t _s2 ) of the first receive window signal (SF1) depends on the first filter output signal (S8).

In a second variant, the second time end (t _e2 ) of the first receive window signal (SF1) depends on the first filter output signal (S8).

In a third variant, the third time start (t _s3 ) of the second receive window signal (SF2) depends on the first filter output signal (S8).

In a fourth variant, the third time end (t _e3 ) of the second receive window signal (SF2) depends on the first filter output signal (S8).

In a fifth variant, the delay time (Δt) depends on the first filter output signal (S8).

The first filter output signal (S8) can already be used as a measured value signal for a transit time of the first signal (s1) in the transmission path (I1). However, it has been shown that it is favorable to provide a subsequent second filter (F2), in particular a low-pass filter, that the actual first output signal (S4) be used as the measured value for the transit time determination of the first signal (s1) and / of the second signal (s2 ) in total in the first transmission path (I1).

In a further embodiment of the proposed device, the first filter (F1) integrates the difference between the first internal signal (S2a) and the second internal signal (S2b) into a first filter output signal (S8).

In a third embodiment of the proposed device, the first receive window signal (SF1) from the time start (t _sz ) of the relevant period (T _z ) to the second time start (t _s2 ) of the first receive window signal (SF1) is absolute zero. The first receive window signal (SF1) increases in its amount in this form from the second time start (t _s2 ) of the first receive window signal (SF1) in time monotonically increasing or jumping. In this case, a slow increase in the amount of the first receiving window signal (SF1) is to be preferred over the sudden increase for reducing the jitter sensitivity of the system. It therefore makes sense if the rise time is longer than 1% of the first minimum constant time (t _k1 ) explained below and / or is at least 1% of the time length of the time interval (T _z ). For a first minimum constancy time (t _k1 ) until the second time end (t _s2 ) of the first receive window signal (SF1), the magnitude of the first receive window signal (SF1) remains at a constant value. In the context of this disclosure, constancy means a change in the amplitude of the first receive window signal (SF1) by less than 25%. The first receive window signal (SF1) drops in terms of magnitude from the second time end (t _e2 ) of the first receive window signal (SF1) temporally monotonically decreasing or leaps and then remains in magnitude until the time end (t _ez ) of the relevant period (T _z ) is zero.

In a fourth embodiment of the proposed device is analogous to the previous expression, the second receiving window signal (SF2) amount of time beginning (t _sz ) of the relevant period (T _z ) to the third temporal beginning (t _s3 ) of the second receiving window signal (SF2) zero , The second receive window signal (SF2) increases in terms of amount from the third time start (t _s3 ) of the second receive window signal (SF2) temporally monotonously or discontinuously and remains in magnitude for a second minimum _constant time (t _k2 ) to third time end (t _e3 ) of the second receive window signal ( SF2) at a constant value. With regard to constancy, the previously written applies. The second receive window signal (SF2) drops in terms of magnitude from the third time end (t _e3 ) of the second receive window signal (SF2) temporally monotonous or jumped and then deducted in absolute terms until the time end (t _ez ) of the relevant period (T _z ) zero.

In a fifth embodiment of the proposed device, the first minimum _{contact time} (t _k1 ) is equal to the second minimum _{constant time} (t _k2 ), which is a preferred expression of the fourth embodiment.

• • der zweite zeitliche Beginn (t_s2) des ersten Empfangsfenstersignals (SF1) und/oder
• • das zweite zeitliche Ende (t_e2) des ersten Empfangsfenstersignals (SF1) und/oder
• • der dritte zeitliche Beginn (t_s3) des zweiten Empfangsfenstersignals (SF2) und/oder
• • das dritte zeitliche Ende (t_e3) des zweiten Empfangsfenstersignals (SF2) und/oder
• • die Verzögerungszeit (Δt)

von dem ersten Filterausgangssignal (S8) und/oder einem später beschriebenen ersten digitalisierten Filterausgangssignal (S9) abhängen.In a sixth embodiment, the first minimum _contact time (t _k1 ) and / or the second minimum _constant time (t _k2 ) is greater than the time resolution with the

• The second time start (t _s2 ) of the first receive window signal (SF1) and / or
• The second temporal end (t _e2 ) of the first receiving window signal (SF1) and / or
• The third time start (t _s3 ) of the second receive window signal (SF2) and / or
• The third time end (t _e3 ) of the second receive window signal (SF2) and / or
• The delay time (Δt)

depend on the first filter output (S8) and / or a later-described first digitized filter output (S9).

• • der zweite zeitliche Beginn (t_s2) des ersten Empfangsfenstersignals (SF1) und/oder
• • das zweite zeitliche Ende (t_e2) des ersten Empfangsfenstersignals (SF1) und/oder
• • der dritte zeitliche Beginn (t_s3) des zweiten Empfangsfenstersignals (SF2) und/oder
• • das dritte zeitliche Ende (t_e3) des zweiten Empfangsfenstersignals (SF2) und/oder
• • die Verzögerungszeit (Δt)

von dem ersten Filterausgangssignal (S8) und/oder einem ersten digitalisierten Filterausgangssignal (S9) plus der Anstiegszeit (t_a), mit der der Sender (H) zu senden beginnt, plus der Abfallszeit (t_f), mit der der Sender (H) zu senden aufhört, abhängt.In a seventh embodiment, the first minimum _contiguous time (t _k1 ) and / or the second minimum _constancy time (t _k2 ) is greater than the temporal sum of the time resolution with which

• The second time start (t _s2 ) of the first receive window signal (SF1) and / or
• The second temporal end (t _e2 ) of the first receiving window signal (SF1) and / or
• The third time start (t _s3 ) of the second receive window signal (SF2) and / or
• The third time end (t _e3 ) of the second receive window signal (SF2) and / or
• The delay time (Δt)

from the first filter output signal (S8) and / or a first digitized filter output signal (S9) plus the rise time (t _a ) at which the transmitter (H) begins to transmit plus the fall time (t _f ) at which the transmitter (H ) to stop sending depends.

In an eighth embodiment of the proposed device, the first filter (F1) is a linear filter with a filter function f (ΔS2). Here ΔS2 is the difference signal from the first internal signal (S2a) and the second internal signal ( 22b ). However, the filter function f () can first be seen in general terms and be considered as a feature of the filter per se. This purely mathematical feature, which is reflected in the technical realization of the filter, can also be applied to individual signals in order to characterize these signals.

In a ninth embodiment of the proposed device, the change in the magnitude of a filter function f () dependent on the second receive window signal (SF2) is in accordance with the predicted from the time start (t _sz ) of the relevant time period (T _z ) to the time end (t _ez ) of the relevant time segment (T _z ) equal to the amount change of the first receive window signal (SF1) dependent filter function f () according to the predicted from the time start (t _sz ) of the relevant period to the time end (t _ez ) of the relevant period (T _z ). This means nothing else than that the first receive window signal (SF1) and the second receive window signal (SF2) should behave the same when filtered by the first filter (F1). Since the first filter (F1) is linear, a subtraction of the receive window signals thus results in a vanishing first filter output (F8).

In a tenth embodiment of the proposed device, the time integral of the second receive window signal (SF2) from the time start (t _sz ) of the relevant time section (T _z ) to the end of time (t _ez ) of the relevant time section (T _z ) is equal to the integral of first reception window signal (SF1) from the time start (t _sz ) of the relevant time section (T _z ) to the end of time (t _ez ) of the relevant time section (T _z ). As mentioned above, the integration is indeed a special possible form of the first filter (F1). The tenth embodiment of the proposed device is thus only a special form of the ninth embodiment with a first filter (F1) in the form of an integrator.

• • der zweite zeitliche Beginn (t_s2) des ersten Empfangsfenstersignals (SF1) und/oder
• • das zweite zeitliche Ende (t_e2) des ersten Empfangsfenstersignals (SF1) und/oder
• • der dritte zeitliche Beginn (t_s3) des zweiten Empfangsfenstersignals (SF2) und/oder
• • das dritte zeitliche Ende (t_e3) des zweiten Empfangsfenstersignals (SF2) und/oder
• • die Verzögerungszeit (Δt)

von dem ersten digitalisierten Filterausgangssignal (S9) statt von dem ersten Filterausgangssignal (S8) ab. Das erste Filterausgangssignal (S8) und/oder das erste digitalisierte Filterausgangssignal (S9) und/oder ein oder mehrere aus diesen, insbesondere durch einen oder mehrere nachfolgende zweite Filter (F2), abgeleitete erste Ausgangssignale (S4) werden wieder innerhalb dieses betreffenden Zeitabschnitts (T_z) als Messwert für die Laufzeitbestimmung des ersten Signals (s1) in der Übertragungsstrecke (I1) verwendet.In an eleventh embodiment of the proposed device, the first filter output signal (S8) is converted by an analog-to-digital converter (ADC) and / or a time-to-digital converter (TDC) into a discrete-value first digitized filter output signal (S9) , In this case, a time-to-digital converter (TDC) should always be given preference, because this allows increased resolution. It depends then at least

• The second time start (t _s2 ) of the first receive window signal (SF1) and / or
• The second temporal end (t _e2 ) of the first receiving window signal (SF1) and / or
• The third time start (t _s3 ) of the second receive window signal (SF2) and / or
• The third time end (t _e3 ) of the second receive window signal (SF2) and / or
• The delay time (Δt)

from the first digitized filter output (S9) instead of the first filter output (S8). The first filter output signal (S8) and / or the first digitized filter output signal (S9) and / or one or more first output signals (S4) derived therefrom, in particular by one or more subsequent second filters (F2), are readjusted within this respective time period (FIG. T _z ) as a measured value for the transit time determination of the first signal (s1) in the transmission path (I1) used.

The twelfth embodiment of the proposed device relates to a two-stage delta-sigma system. To this end, a first summer (Σ1) sums the filter output signal (S8) and a first correction signal (SK1) to a second filter input signal (S10). A third linear filter (F3) with a filter function f ₃ (S10) filters the second filter input signal (S10) to a third filter output signal (S11). The third filter output signal (S11) is now converted into the discrete-value first digitized filter output signal (S9) instead of the first filter output signal (S8) by an analog-to-digital converter (ADC) or a time-to-digital converter (TDC). Again, the variant with the time-to-digital converter (TDC) to give preference. A correction signal generating unit (KE), which preferably converts the digitized filter output signal (S9) into a charge quantity for the third filter (F3), which is preferably a further integrator, now generates the first correction signal (SK1), which is preferably a charge signal Dependence on the digitized filter output signal (S9). This design of a second integration loop has the merit of minimizing noise and control errors.

• • der zweite zeitliche Beginn (t_s2) des ersten Empfangsfenstersignals (SF1) und/oder
• • das zweite zeitliche Ende (t_e2) des ersten Empfangsfenstersignals (SF1) und/oder
• • der dritte zeitliche Beginn (t_s3) des zweiten Empfangsfenstersignals (SF2) und/oder
• • das dritte zeitliche Ende (t_e3) des zweiten Empfangsfenstersignals (SF2) und/oder
• • die Verzögerungszeit (Δt)

hängen in dieser dreizehnten Ausprägung der vorgeschlagenen Vorrichtung von dem ersten Reglerausgangssignal (S12) statt von dem ersten digitalisierten Filterausgangssignal (S9) oder dem ersten Filterausgangssignal (S8) ab.In a thirteenth embodiment of the proposed device, a controller (CTR) generates a first one depending on the filter output signal (S8) and / or the digitized filter output signal (S9) and / or the third filter output signal (S11) and possibly a default value (Ref) Controller output signal (S12). At least

• The second time start (t _s2 ) of the first receive window signal (SF1) and / or
• The second temporal end (t _e2 ) of the first receiving window signal (SF1) and / or
• The third time start (t _s3 ) of the second receive window signal (SF2) and / or
• The third time end (t _e3 ) of the second receive window signal (SF2) and / or
• The delay time (Δt)

In this thirteenth aspect of the proposed device depend on the first regulator output signal (S12) instead of the first digitized filter output signal (S9) or the first filter output signal (S8).

In a fourteenth embodiment of the proposed device, the controller (CTR) is a PID controller.

In a fifteenth embodiment of the proposed device, the controller (CTR) or a sub-device of the controller (CTR) has a hysteresis. This has the advantage that the system is less susceptible to interference.

• • der zweite zeitliche Beginn (t_s2) des ersten Empfangsfenstersignals (SF1) und/oder
• • das zweite zeitliche Ende (t_e2) des ersten Empfangsfenstersignals (SF1) und/oder
• • der dritte zeitliche Beginn (t_s3) des zweiten Empfangsfenstersignals (SF2) und/oder
• • das dritte zeitliche Ende (t_e3) des zweiten Empfangsfenstersignals (SF2) und/oder
• • die Verzögerungszeit (Δt)

hängen von dem Temperatursensorsignal (TSS) zumindest zeitweise innerhalb des betreffenden Zeitabschnitts (T_z) ab.In a sixteenth embodiment of the proposed device, the device has a temperature sensor (TS) for detecting the temperature (T) of the transmitter (H) or a temperature related thereto in the form of a temperature sensor signal (TSS). At least

• The second time start (t _s2 ) of the first receive window signal (SF1) and / or
• The second temporal end (t _e2 ) of the first receiving window signal (SF1) and / or
• The third time start (t _s3 ) of the second receive window signal (SF2) and / or
• The third time end (t _e3 ) of the second receive window signal (SF2) and / or
• The delay time (Δt)

depend on the temperature sensor signal (TSS) at least temporarily within the relevant time period (T _z ).

• • der zweite zeitliche Beginn (t_s2) des ersten Empfangsfenstersignals (SF1) und/oder
• • das zweite zeitliche Ende (t_e2) des ersten Empfangsfenstersignals (SF1) und/oder
• • der dritte zeitliche Beginn (t_s3) des zweiten Empfangsfenstersignals (SF2) und/oder
• • das dritte zeitliche Ende (t_e3) des zweiten Empfangsfenstersignals (SF2) und/oder
• • die Verzögerungszeit (Δt)

von dem Sendestommesssignal (I_MS) zumindest zeitweise ab.In a seventeenth embodiment of the proposed device, the electrical transmitter current (I _H ) which the transmitter (H) receives is evaluated and used for transmitter temperature estimation. Therefore, in this variant, the device comprises a transmission current detection device (I _HM ) which supplies a transmission test signal (I _MS ). In this case, preferably depends at least

• The second time start (t _s2 ) of the first receive window signal (SF1) and / or
• The second temporal end (t _e2 ) of the first receiving window signal (SF1) and / or
• The third time start (t _s3 ) of the second receive window signal (SF2) and / or
• The third time end (t _e3 ) of the second receive window signal (SF2) and / or
• The delay time (Δt)

from the Sendestommesssignal (I _MS ) at least temporarily.

It has been shown that it is sensible and advantageous not to change the temporal parameters of the reception window signal (SF1, SF2) independently of each other.

In an eighteenth aspect of the proposed device, therefore, either the second time start (t _s2 ) of the first receive window signal (SF1) is equal to the second time end (t _e2 ) of the first Receive window signal (SF1) and the third time start (t _s3 ) of the second receive window signal (SF2) is after the third time end (t _e3 ) of the second receive window signal (SF2) or the second time start (t _s2 ) of the first receive window signal (SF1) is after the second temporal end (t _e2 ) of the first receiving window signal (SF1) and the third temporal beginning (t _s3 ) of the second receiving window signal (SF2) is equal to the third temporal end (t _e3 ) of the second receiving window signal (SF2).

In a nineteenth embodiment of the proposed device, the second time start (t _s2 ) of the first receive window signal (SF1) and the third time start (t _e3 ) of the second receive window signal (SF2) depend in the same way on the first filter output signal (S8) and / or the first digitized filter output signal (S9) and / or the third filter output signal (S11) and / or the first regulator output signal (S12). Equality here means that the corresponding derivatives of these times do not differ in terms of the sign according to the levels of these signals and differ by no more than 25% in terms of magnitude.

In a twentieth form of the proposed device, the second temporal beginning (t _s2 ) of the first receiving window signal (SF1) and the third temporal end (t _e3 ) of the second receiving window signal (SF2) depend in the same way on the first filter output signal (S8) and / or the first digitized filter output signal (S9) and / or the third filter output signal (S11) and / or the first regulator output signal (S12). Here, too, equality means that the corresponding derivatives of these times do not differ in terms of the sign according to the levels of these signals and do not differ in magnitude by more than 25%.

In a twenty-first embodiment of the proposed device, the second temporal end (t _e2 ) of the first receiving window signal (SF1) and the third temporal end (t _e3 ) of the second receiving window signal (SF2) depend in the same way on the first filter output signal (S8) and / or the first digitized filter output signal (S9) and / or the third filter output signal (S11) and / or the first regulator output signal (S12). Here, too, equality means that the corresponding derivatives of these times do not differ in terms of the sign according to the levels of these signals and do not differ in magnitude by more than 25%.

In a twenty-second embodiment of the proposed device, the second temporal end (t _e2 ) of the first receiving window signal (SF1) and the third temporal beginning (t _s3 ) of the second receiving window signal (SF2) depend in the same way on the first filter output signal (S8) and / or the first digitized filter output signal (S9) and / or the third filter output signal (S11) and / or the first regulator output signal (S12). Here, too, equality means that the corresponding derivatives of these times do not differ in terms of the sign according to the levels of these signals and do not differ in magnitude by more than 25%.

In addition to these variants, a variant is of particular interest. In this case, the system has several receivers, a first receiver (D1) and a second receiver (D2), the control loop then preferably refers only to the temporal parameters of the corresponding receive window signals. Of course, from the receiver output signals (S0, S0B), a control signal for the time delay of the transmission signal (S5) to the delayed transmission signal (S5d) can be synthesized. It is easiest, however, if then this delay is assigned to a receiver or a sum signal of the respective filter output signals (S8, S8d), etc. is assigned.

• • der fünfte zeitliche Beginn (t_s5) des dritten Empfangsfenstersignals (SF3) und/oder
• • das fünfte zeitliche Ende (t_e5) des dritten Empfangsfenstersignals (SF3) und/oder
• • der sechste zeitliche Beginn (t_s6) des vierten Empfangsfenstersignals (SF4) und/oder
• • das sechste zeitliche Ende (t_e6) des vierten Empfangsfenstersignals (SF4) und/oder
• • die Verzögerungszeit (Δt)

hängen von dem vierten Filterausgangssignal (S8B) ab. Das vierte Filterausgangssignal (S8B) und/oder ein daraus, insbesondere durch einen nachfolgenden fünften Filter (F5), abgeleitetes weiteres Ausgangssignal (S4B) wird innerhalb dieses betreffenden Zeitabschnitts (T_z) als weiterer Messwert für die Laufzeitbestimmung des vierten Signals (s4) in der zweiten Übertragungsstrecke (I2) verwendet. Das fünfte Filter (F5) ist vorzugsweise ein Tiefpassfilter.A twenty-third expression of the proposed device therefore serves for the parallel determination of the propagation time in a second transmission path (I2), which may coincide completely or partially with the first transmission path (I1) and contain the object (O) and / or a further object (O2) can, between the transmitter (H) and at least one other receiver (D2). The transmitter (H) now sends in dependence on the delayed transmission signal (S5d) a third, in particular optical, signal (s3) in a time-wise manner into the second transmission path (I2). Typically, this configuration will be such that the transmitter transmits an optical signal, a first part of this optical signal entering the first transmission path (i1) forming the first signal (s1) and a second part entering the second transmission path (I2) and the third signal (s3) forms. Thus, typically the first signal (s1) and the second signal (s2) are synchronous. Therefore, the third signal (s3) is also provided with a carrier signal as a signal component. This carrier signal is thus modulated at least with a modulation signal in the amplitude and / or phase and / or polarization and / or wavelength and / or amplitude modulation frequency and / or the spectral composition. In each time period (T _z ) in which the transmitter (H) transmits the third signal (s3), the third signal (s3) has a fourth time start (t _s4 ) and a fourth time within this relevant time period (T _z ) End (t _e4 ). The second transmission path (I2) modifies the third signal (s3) when passing through this second transmission path (I2) to a fourth, in particular optical, signal (s4). Again, this modification may relate to the amplitude and / or the phase and / or the polarization and / or the wavelength and / or the amplitude modulation frequency and / or the spectral composition of the fifth signal compared to the fourth signal Phase change again corresponds to the delay in a row of the term. The further receiver (D2) receives the fourth signal (s4) after exiting the second transmission path (I2). In the further receiver (D2), the further receiver (D2) converts the fourth signal (s4) into a further receiver output signal (S0B). A third multiplier (M3) multiplies the further receiver output signal (S0B) by a third receive window signal (SF3) to a third internal signal (S2Ba). The third receive window signal (SF3) has a fifth time start (t _s5 ) within the relevant time segment (T _z ), which occurs before the fourth time start (t _s4 ) of the third signal (s4) and before the fourth time end (t _e4 ) of the fourth signal (s4) is located. The third receive window signal (SF3) has a fifth time end (t _e5 ) within the relevant time segment (T _z ), which occurs after the fourth time start (t _s4 ) of the fourth signal (s4) and before the fourth time end (t _e4 ) of the fourth signal (s4) is located. A fourth multiplier (M4) multiplies the further receiver output signal (S0B) by a fourth receive window signal (SF4) to a fourth internal signal (S2Bb). The fourth receive window signal (SF4) has a sixth time start (t _s6 ) well within the relevant time interval (T _z ), which occurs after the fourth time start (t _s4 ) of the fourth signal (s4) and before the fourth time end (t _e4 ) of the fourth signal (s4) is located. The fourth receive window signal (SF4) has a sixth time end (t _e6 ) within the relevant time segment (T _z ) which occurs after the fourth time start (t _s4 ) of the fourth signal (s4) and after the fourth time end (t _e4 ) of the fourth signal (s4) is located. A fourth filter (F4), which is preferably an integrator or a low-pass filter or a band-pass filter, filters the difference between the third internal signal (S2Ba) and the fourth internal signal (S2Bb) into a fourth filter output signal (S8B). At least

• The fifth time start (t _s5 ) of the third receive window signal (SF3) and / or
• The fifth time end (t _e5 ) of the third receive window signal (SF3) and / or
• The sixth time start (t _s6 ) of the fourth receive window signal (SF4) and / or
• The sixth time end (t _e6 ) of the fourth receive window signal (SF4) and / or
• The delay time (Δt)

depend on the fourth filter output (S8B). The fourth filter output signal (S8B) and / or a further output signal (S4B) derived therefrom, in particular by a subsequent fifth filter (F5), is used as a further measured value for the transit time determination of the fourth signal (s4) within this relevant time segment (T _z ) the second transmission path (I2) used. The fifth filter (F5) is preferably a low-pass filter.

Based on this characteristic, a twenty-fourth embodiment of the proposed device is conceivable in which a second summing device (Σ2) from the receiver output signal (S0) and the further receiver output signal (S0B) forms a receiver output sum signal (S0Σ) by summation, which is the basis of the control. Thus, an average in the form of a distance can be measured directly. The control is then performed such that the third multiplier (M3) multiplies the receiver output sum signal (S0Σ) instead of the further receiver output signal (S0B) by the third reception window signal (SF3) to the third internal signal (S2Ba). The fourth multiplier (M4) multiplies the receiver output sum signal (S0Σ) instead of the further receiver output signal (S0B) by the fourth reception window signal (SF4) to the fourth internal signal (S2Bb).

Instead of summation, a difference can also be made. For small signals, one then directly obtains the angle by triangulation. In such a twenty-fifth embodiment of the proposed device, a fourth differencing device (ΔS) from the receiver output signal (S0) and the further receiver output signal (S0B) forms a receiver output difference signal (S0Δ) by subtraction. As before, the control can now be carried out analogously to that in the summation. The third multiplier (M3) multiplies the receiver output difference signal (S0Δ), instead of the further receiver output signal (S0B), by the third receiving window signal (SF3) to the third internal signal (S2Ba). The fourth multiplier (M4) multiplies the receiver output difference signal (S0Δ) instead of the further receiver output signal (S0B) by the fourth reception window signal (SF4) to the fourth internal signal (S2Bb).

The following expressions concern the execution of the multipliers.

In a twenty-sixth embodiment of the proposed device, the first multiplier (M1) is implemented as an analog switch. In this embodiment of the proposed device, the first multiplier outputs either the receiver output signal (S0) or a predetermined fixed potential as the first internal signal (S2a) in response to the first receive window signal (SF1). Since the device should be symmetrical, the second multiplier (M2) is then also implemented as an analog switch which outputs either the receiver output signal (S0) or a predetermined fixed potential as a second internal signal (S2b) in response to the second receive window signal (SF2).

In a twenty-seventh embodiment of the proposed device, the first multiplier (M1) is also implemented as an analog switch connecting the receiver output signal (S0) to the first internal signal (S2a) and separating the receiver output signal (S0) from the first receiver (D1) the first receive window signal (SF1) is in a first state. The first multiplier (M1) separates the receiver output signal (S0) from the first internal signal (S2a) and connects the receiver output signal (S0) to the first receiver (D1) when the first receive window signal (SF1) is in a second state. The second multiplier (M2) is also designed for balancing as an analog switch which connects the receiver output signal (S0) to the second internal signal (S2b) and separates the receiver output signal (S0) from the first receiver (D1) when the second receive window signal (S0) SF2) is in a first state. The second multiplier (M2) separates the receiver output signal (S0) from the second internal signal (S2b) and connects the receiver output signal (S0) to the first receiver (D1) when the second receive window signal (SF2) is in a second state.

In a twenty-seventh embodiment of the proposed device, the first multiplier (M1) is implemented as an analogue switch which connects the receiver output signal (S0) to the first internal signal (S2a) and disconnects the receiver output signal (S0) from the first receiver (D1) the first receiving window signal (SF1) is in a first state. The first multiplier (M1) disconnects the receiver output signal (S0) from the first internal signal (S2a) and connects the receiver output signal (S0) and the first receiver (D1) and disconnects the receiver (D) from the current or voltage source when the first receive window signal (SF1) is in a second state. The second multiplier (M2) is implemented as an analog switch which connects the receiver output signal (S0) to the second internal signal (S2b) and disconnects the receiver output signal (S0) from the first receiver (D1) when the second receive window signal (SF2) in a first state is located. The second multiplier (M2) separates the receiver output signal (S0) from the second internal signal (S2b) and connects the receiver output signal (S0) to the first receiver (D1) when the second receive window signal (SF2) is in a second state. The apparatus then includes, in addition, a divider which connects the receiver output signal (S0) to a source of current or voltage when the receiver output signal (S0) is not connected to either the first internal signal (S2a) or the second internal signal (S2b) ,

• • der zweite zeitliche Beginn (t_s2) des ersten Empfangsfenstersignals (SF1) und/oder
• • das zweite zeitliche Ende (t_e2) des ersten Empfangsfenstersignals (SF1) und/oder
• • der dritte zeitliche Beginn (t_s3) des zweiten Empfangsfenstersignals (SF2) und/oder
• • das dritte zeitliche Ende (t_e3) des zweiten Empfangsfenstersignals (SF2) und/oder
• • die Verzögerungszeit (Δt)

von dem ersten Filterausgangssignal (S8) abhängen.The invention also includes an associated method. It is a method for determining the transit time of a first, preferably optical signal (s1) in a first transmission path (I1), which may contain an object (O), between a transmitter (H) and a first receiver (D1). The method includes steps that are typically performed in parallel and / or quasi-parallel. These steps include the optional, at least temporary delaying of a transmission signal (S5) by a delay time (Δt) to a delayed transmission signal (S5d), in particular by either a delay unit (.DELTA.T) or the delayed transmission signal (S5d) equal to the transmission signal (S5) is. As a further step, the method comprises, based on a period of time (T _z) time sections Into ends of a, in particular optical, first signal (s1) into said first transmission path (I1) in response to the delayed transmitted signal (S5d), in particular by a transmitter (H ). In this case, the first signal (s1) has at least one carrier signal as signal component, which is modulated at least with a modulation signal in the amplitude and / or phase and / or polarization and / or wavelength and / or amplitude modulation frequency and / or the spectral composition. In each time segment (T _z ) in which, in particular, the transmitter (H) transmits the first signal (s1), the first signal (s1) has a first time start (t _s1 ) and a first within this relevant time interval (T _z ) temporal end (t _e1 ). As a further step, the method comprises modifying the first signal (s1) when passing through the first transmission path (I1) to form a, in particular optical, second signal (s2). In this case, this modification relates to the amplitude and / or the phase and / or the polarization and / or the wavelength and / or the amplitude modulation frequency and / or the spectral composition of the second signal (s2) in comparison to the first signal (s1). As a further step, the method comprises receiving the second signal (s2) after exiting the transmission path (I1) within this relevant time segment (T _z ), in particular by the first receiver (D1). A further step comprises converting the second signal (s2) into a receiver output signal (S0), in particular in the first receiver (D1). Furthermore, the method comprises the step of multiplying the receiver output signal (S0) by a first receive window signal (SF1) to a first internal signal (S2a), in particular by a first multiplier (M1). The first receive window signal (SF1) has a second time start (t _s2 ) within the relevant time segment (T _z ) which occurs before the first time start (t _s1 ) of the first signal (s1) and before the time End (t _e1 ) of the first signal (s1) is located. The first receive window signal (SF1) has a second time end (t _e2 ) within the relevant time segment (T _z ) which occurs after the first time start (t _s1 ) of the first signal (s1) and before the end of time ( t _e1 ) of the first signal (s1) is located. A parallel step of the method comprises multiplying the receiver output signal (S0) by a second receive window signal (SF2) to a second internal signal (S2b) within that respective time period (T _z ), in particular by a second multiplier (M2). In this case, the second receiving window signal (SF2) within the relevant time period concerned (T _z ) on a third time start (t _s3 ), the time after the first time start (t _s1 ) of the first signal (s1) and before the time end (t _e1 ) of the first signal (s1) is located. The second receive window signal (SF2) has a third time end (t _e3 ) within the relevant time segment (T _z ) which occurs after the first time start (t _s1 ) of the first signal (s1) and after the end of time ( t _e1 ) of the first signal (s1) is located. Another step is filtering the difference between the first internal signal (S2a) and the second internal signal (S2b) to a first filter output signal (S8), in particular by a first filter (F1). Likewise, the method comprises forming an output signal (S4) as a function of the first filter output signal (S8) and / or using the first filter output signal (S8) as output signal (S4), in particular by a subsequent second filter (F2). The use of the output signal (S4) as a representative of a measured value for the transit time determination of the first signal (s1) and / of the second signal (s2) in total in the first transmission path (II) is also part of the method. Quite essential for the method according to the invention is that at least

• The second time start (t _s2 ) of the first receive window signal (SF1) and / or
• The second temporal end (t _e2 ) of the first receiving window signal (SF1) and / or
• The third time start (t _s3 ) of the second receive window signal (SF2) and / or
• The third time end (t _e3 ) of the second receive window signal (SF2) and / or
• The delay time (Δt)

depend on the first filter output (S8).

• • eines oder beider Empfangsfenster (SF1, SF2) in Relation zu dem ersten Signal (s1) und/oder
• • der zeitlichen Lage des ersten Signals (s1) in Relation zu den beiden Empfangsfenstern (SF1, SF2), und/oder
• • der ersten zeitlichen Länge (T1) des ersten Empfangsfensters und/oder
• • der zweiten zeitlichen Länge (T2) des zweiten Empfangsfensters (SF1, SF2)

genutzt.A thirtieth embodiment of the method relates to a method for determining the transit time for a first, in particular optical, signal (s1) in a first transmission path (I1) between a transmitter (H) and a first receiver (D1). In this case, the transmitter (H) transmits a first signal (s1) into the first transmission link (I1), which after passage (and thus delay) through at least a part of the first transmission link (I1) from the first receiver (D1) as a second signal (s2), which is a modified first signal (s1), is received and converted into a receiver output signal (S0). In the first receiver (D1), the second signal (s2) is evaluated in two reception windows, a first reception window (SF1) with a first time length (T1) and a second reception window (SF2) with a second time length (T2) , The beginning of the first signal (s1) is exclusively in the first receiving window (SF1) and the end of the first signal (s1) is contained exclusively in the second receiving window (SF2). The method is characterized in that the receiver output signal (S0) comprises a first signal portion to be associated with the first receive window (SF1) and a second signal portion to be associated with the second receive window (SF2), which is over a predefined period of time (T _z ) averaged first signal component except for a deviation is the same as the over the time period (T _z ) averaged second signal component. This deviation is at least temporarily as a control signal for the temporal position

• • one or both receive windows (SF1, SF2) in relation to the first signal (s1) and / or
• The temporal position of the first signal (s1) in relation to the two receiving windows (SF1, SF2), and / or
• The first time length (T1) of the first reception window and / or
• The second time length (T2) of the second reception window (SF1, SF2)

used.

In a further embodiment of this method, this deviation and a first correction signal (SKE) are added together (summed). In the signal path, this sum is then integrated and the resulting integration result is used instead of said deviation as a control signal.

Description of the figures

1 shows a basic configuration of the proposed device

2 shows the proposed device using a two-stage delta-sigma method

3 shows a particularly simple variant of the proposed device

4 shows a timing diagram of the receive window signals (SF1) and (SF2) and of the first signal (s1)

Fig. 1

In 1 a general version of the proposed device is shown. The transmission signal (S5) is delayed in the delay unit (ΔT) to the delayed transmission signal (S5d). This delay depends on the digitized filter output (S9). The delayed transmission signal (S5d) controls the transmitter (H) via the transmission amplifier (V2), which is a laser diode here. Particularly preferably, the transmission signal (S5) is a pulsed signal. The transmitter (H) transmits into the first transmission link (I1), part of which is the object (O). the first receiver (D1) receives the signal modified by the passage through the first transmission link and converts it into the receiver output signal (S0) amplified by the input amplifier (V1). The first multiplier (M1) multiplies the receiver output signal (S0) by the first reception window signal (SF1) to the first internal signal (S2a). The second multiplier (M2) multiplies the receiver output signal (S0) by the second reception window signal (SF2) to the second internal signal (S2b). Here, the first filter (F1) integrates the difference of the first internal signal (S2a) and the second internal signal (S2b) to the first filter output signal (S8). A time-to-digital converter digitizes the signal to the digitized filter output (S9). Preferably, it is a comparator or an inverter or the like. In this example, by the digital filter output signal (S9), a controller (CTR) controlled by means of a digital-to-time signal converter (DTC) the second start (t _s2 ) of the first receiving window signal (SF1) and the second end (t _e2 ) of the first receive window signal (SF1) and the third start (t _s3 ) of the second receive window signal (SF2) and the third end (t _e3 ) of the second receive window signal (SF2) and said delay of the transmit signal (S5) to the delayed transmit signal (S5d ) certainly. Typically, the digital-to-time signal converter is a combination of multiplexers that hardwire or programmably or adjustably tap the digitized filter output (S9) incrementally delayed in a delay chain at the various stages.

A digital-to-analog converter simultaneously generates the output signal (S4) from the digitized filter output signal (S9), more precisely from signals derived therefrom after filtering in a low-pass filter (F2).

Fig. 2

2 equals to 1 with the difference that the filter output signal (S8) is summed with a first correction signal (SK1) to a second filter input signal (S10) and then integrated in a third filter (F3) to form a third filter output signal (F11) which is then input to the filter output signal Time-to-digital converter (TDC) is used. The first correction signal (SK1) is generated by a correction signal generation unit (KE), which is typically a digital-to-charge conversion unit, in response to the digitized filter output signal (S9). This two-stage delta-sigma conversion minimizes system noise, in particular quantization errors, and thus maximizes the resolution of the measurement.

Fig. 3

3 corresponds to a simplified version of the 1 , In this example as well, the controller (CTR) is controlled by the digital filter output signal (S9), but by means of a digital-to-time signal converter (DTC) only the second start (t _s2 ) of the first receive window signal (SF1) and the third Beginning (t _s3 ) of the second receiving window signal (SF2) and the said delay of the transmission signal (S5) to the delayed transmission signal (S5d) is determined. The second end (t _e2 ) of the first receive window signal (SF1) and the third end (t _e3 ) of the second receive window signal (SF2) are either synchronously delayed by a fixed temporal window size or alternatively kept constant. The only remaining output signal of the controller (CTR) can be used directly via the low pass (F2) as an output signal (S4).

Fig. 4

4 shows a timing diagram of the receive window signals (SF1) and (SF2) and of the first signal (s1)

Advantages of the invention

• 1. Länge Auszeiten der LED
• 2. Niedrige Anforderungen an Offset und Verstärkung der Verstärkerkette
• 3. niedrigere Stromaufnahme oder höhere Bandbreite
• 4. Skalierbarkeit (mehrere Fotodioden im Parallelbetrieb)
• 5. Leichte Handhabung ohne optische Kopplung ermöglicht Chiplösungen
• 6. Niedriger Preis

These changes provide significant benefits:

• 1. Length of time-out of the LED
• 2. Low demands on offset and gain of the amplifier chain
• 3. lower power consumption or higher bandwidth
• 4. Scalability (several photodiodes in parallel operation)
• 5. Easy handling without optical coupling enables chip solutions
• 6. Low price

LIST OF REFERENCE NUMBERS

.DELTA.S

Differencing device

.DELTA.S2

Difference signal from the first internal signal (S2a) and the second internal signal ( 22b ).

.delta.t

Delay time by which the delay unit (ΔT) delays the transmission signal (S5) to the delayed transmission signal (S5d).

.DELTA.T

delay unit

ADC

Analog-to-digital converter. In the simplest case, it can be a comparator, inverter, Schmitt trigger, etc., as a one-bit analog-to-digital converter.

CTR

regulator

D1

first recipient

D2

additional receiver

DAC

Digital to Analog Converter

f (.DELTA.S2)

Filter function of the first filter (F1) with the parameter signal ΔS2.

F1

first filter. The first filter (F1) is preferably a linear filter with a filter function f (ΔS2), where ΔS2 represents the difference signal from the first internal signal (S2a) and the second internal signal (S2b).

F2

second filter

F3

third filter. The third filter (F3) is preferably a linear filter with a filter function f ₃ (S10).

F4

fourth filter. The fourth filter (F4) is preferably a linear filter with a filter function f ₄ (ΔS2B), where ΔS2B represents the difference signal from the third internal signal (S2Ba) and the fourth internal signal (S2Bb).

F5

fifth filter

H

transmitter

I1

first transmission path

I2

second transmission path

I _H

Transmitter power. This is the electrical current which the transmitter (H) picks up for its operation.

I _HM

Transmission current detecting device for detecting the transmitter current (I _H ).

I _MS

Sendestommesssignal. This signal reflects the transmitter current (I _H ) detected by the transmit current detector (I _HM ).

KE

Correction signal generating unit which forms the first correction signal (SK1) in response to the digitized filter output signal (S9).

LED

light emitting diode

M1

first multiplier

M2

second multiplier

M3

third multiplier

M4

fourth multiplier

O

Object whose distance is to be detected by means of transit time measurement

O2

Another object whose distance is to be detected by means of transit time measurement

Ref

optional default value for the controller (CTR)

Σ1

first summer

Σ2

second summation device

S0

Receiver output signal of the first receiver (D1)

S0B

additional receiver output signal of the additional receiver (D2)

S0Δ

Receiver output difference signal

S0Σ

Receiver output sum signal

s1

first, in particular optical, signal

s2

second, in particular optical, signal that is delayed or otherwise modified by the transit time, in particular with respect to the first signal (s1).

s3

third, in particular optical, signal

s4

fourth, in particular optical, signal that is delayed or otherwise modified by a further transit time, in particular with respect to the third signal (s3).

S2a

first internal signal

S2b

second internal signal

S2Ba

third internal signal

S2Bb

fourth internal signal

S4

first output signal

S4B

another output signal

S5

send signal

s5d

delayed transmission signal

S8

first filter output of the first filter (F1)

S8B

fourth filter output of the fourth filter (F4)

S9

first digitized filter output

S10

second filter input signal

S11

third filter output signal

S12

first controller output signal

SF1

first receive window signal

SF2

second receive window signal

SF3

third reception window signal

SF4

fourth receive window signal

SK1

first correction signal

T

Temperature of the transmitter

t _a

Rise time (t _a ) at which the transmitter (H) begins to transmit.

t _f

Decay time (t _f ) at which the transmitter (H) stops transmitting.

t _k1

first temporal minimum constants time in which the first receive window signal (SF1) is different from zero and changes less than 25% in amplitude, preferably not at all.

t _k2

second temporal minimum constants time in which the second receive window signal (SF2) is different from zero and changes less than 25% in amplitude, preferably not at all.

t ₁

first time start of the first signal (s1)

^t e1

first time end of the first signal (s1)

^t s2

second time start of the first receive window signal (SF1)

t _e2

second time end of the first receive window signal (SF1)

t _s3

third time start of the second receive window signal (SF2)

t _e3

third time end of the second receive window signal (SF2)

t _s4

fourth time start of the third signal (s3)

t _e4

fourth time end of the third signal (s3)

t _ez

time end of the period (T _z )

t _sz

time start of the time period (T _z )

t _s5

fifth time start of the third receive window signal (SF3)

t _e5

fifth time end of the third receive window signal (SF3)

t _s6

sixth time start of the fourth receive window signal (SF4)

t _e6

sixth time end of the fourth receive window signal (SF4)

TS

temperature sensor

TSS

Temperature sensor signal

T _z

period

V1

input amplifier

V2

transmission amplifier

Claims (2)

Method for determining the transit time for a first, in particular optical, signal (s1) in a first transmission path (I1) between a transmitter (H) and a first receiver (D1) a. wherein the transmitter (H) transmits a first signal (s1) into the first transmission path (I1) which after passing through (and thus delaying) through at least a part of the first transmission path (I1) from the first receiver (D1) as a second signal ( s2), which is a modified first signal (s1), is received and converted to a receiver output signal (S0), and b. wherein in the first receiver (D1) the second signal (s2) is evaluated in two time receiving windows, a first receiving window (SF1) having a first time length (T1) and a second receiving window (SF2) having a second time length (T2) is, wherein the beginning of the first signal (s1) exclusively in the first receiving window (SF1) and the end of the first signal (s1) exclusively in the second receiving window (SF2) is characterized, characterized c. in that the receiver output signal (S0) comprises a first signal component to be assigned to the first reception window (SF1) and a second signal component to be assigned to the second reception window (SF2), wherein the first signal component averaged over a predefined period of time (T _z ) except for a deviation is the same as the over the time period (T _z ) averaged second signal component and d. that the deviation is integrated into a first filter output signal (S8) and e. a time-to-digital converter (TDC) converts the first filter output signal (S8) into a digitized filter output signal (S9) and f. that the digitized filter output signal (S9) at least temporarily as a control signal for the temporal position of one or both receiving windows (SF1, SF2) in relation to the first signal (s1) and / or the temporal position of the first signal (s1) in relation to the two Reception windows (SF1, SF2), and / or the first time length (T1) of the first reception window and / or the second time length (T2) of the second reception window (SF1, SF2) is used. A method according to claim 1, characterized a. in that a first correction signal (SK1) is generated as a function of the digitized filter output signal (S9) and b. that the first filter output signal (S8) and the first correction signal (SK1) are summed c. and then this sum is integrated and d. then this integration result (S11) is converted into the first digitized filter output signal (S9) instead of the first filter output signal (S8).

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