Time measurement circuit and optoelectronic distance meter having such a time measurement circuit

Patent metadata

Field	Value
Publication number	US-2016349368-A1
Application number	US-201615167945-A
Country	US
Kind code	A1
Filing date	May 27, 2016
Priority date	May 29, 2015
Publication date	Dec 1, 2016
Grant date	—

Abstract

Some embodiments of the invention relate to a time measurement circuit for an incoming signal. In some embodiments, the time measurement circuit has a comparator stage, for generating a comparator output signal depending on a fulfillment of a criterion by the incoming signal, wherein exceeding or falling below a threshold value is defined as the criterion. Furthermore, a digitization stage is provided, for sampling, which is performed at a defined sampling rate, of an input signal fed to the digitization stage and converting it into digital data containing sampled values for the input signal, and an evaluation unit for determining a chronological location for the incoming signal by evaluating the digital data.

First claim

1 - 14 . (canceled)

15 . A time measurement circuit for an incoming signal, the time measurement circuit comprising:
a comparator circuit stage for generating a comparator output signal depending on a fulfillment of a criterion by the incoming signal, wherein exceeding or falling below a threshold value is defined as the criterion; a digitization circuit stage for sampling, which is performed at a defined sampling rate, of an input signal fed to the digitization circuit stage and converting it into digital data containing sampled values for the input signal; an evaluation circuit unit for determining a chronological location for the incoming signal by evaluating the digital data; and a signal generating stage interconnected between the comparator circuit stage and the digitization stage, which is designed to generate and output, in a chronologically fixed manner dependent on the content of the comparator output signal, a shape signal, which is designed for post-sampling interpolation ability, of known shape, wherein the evaluation circuit unit is designed to determine a time for the incoming signal while using a chronological interpolation of the values contained in the digital data and the known shape of the shape signal.

16 . Time measurement circuit according to claim 15 , wherein:
the signal generating stage is designed such that the shape signal is pulsed with defined pulse width and changes its signal values asynchronously to the sampling rate of the digitization circuit stage multiple times within the pulse width, wherein the shape signal is formed as: bell-shaped, sawtoothed, triangular, trapezoidal, or stepped.

17 . Time measurement circuit according to claim 15 , wherein:
the signal generating stage comprises at least one flip-flop circuit and a low-pass filter.

18 . Time measurement circuit according to claim 15 , wherein:
the signal generating stage comprises at least one D flip-flop and a low-pass filter.

19 . An optoelectronic distance meter according to the time-of-flight principle, the distance meter comprising:
at least one light source for emitting at least one pulsed light signal, onto a target object, a receiving circuit having a detector for detecting the light signal returning from the target object and signal processing electronics downstream from the detector, and an evaluation circuit unit for determining a distance to the target object, wherein: a time measurement circuit according to claim 1 is provided as part of the signal processing electronics and the evaluation unit.

20 . A distance meter according to claim 19 , wherein:
the comparator circuit stage of the time measurement circuit is designed and provided with criteria such that a comparator output signal is generated and output in each case for a rising flank and for a falling flank of the returning detected light signal, the evaluation circuit unit of the time measurement circuit is designed for determining a first time, that for the rising flank, and a second time, that for the falling flank, and the evaluation circuit unit of the distance meter is designed for deriving a distance to the target object depending on the determined first time and the determined second time.

21 . A distance meter according to claim 19 , wherein:
the comparator circuit stage of the time measurement circuit is designed and provided with criteria such that a comparator output signal is generated and output in each case for a rising flank of the returning detected light signal depending on at least one first and one second set trigger threshold, the evaluation circuit unit of the time measurement circuit is designed for determining a first time, that for exceeding the first trigger threshold, and a second time, that for exceeding the second trigger threshold, and the evaluation circuit unit of the distance meter is designed for deriving a distance to the target object depending on the determined first time and the determined second time, wherein a quality specification about the distance determination is furthermore also derivable depending on the determined first time and the determined second time.

22 . A distance meter according to any one of claim 19 , wherein:
the signal processing electronics have a first and a second channel, wherein the time measurement circuit is provided in the first channel and it is therefore provided for the case of an activation of the detector, which is caused by the returning light signal, in its middle and upper amplitude range, and the second channel is provided for the case of an activation of the detector, which is caused by the returning light signal, in its lower linear amplitude range and for this purpose has a digitization circuit stage for sampling, which is performed at a defined sampling rate, of the detected light signal and converting it into digital WFD data containing sampled values and an evaluation circuit unit for determining a chronological location of the detected light signal in consideration of a pulse shape, which is depicted on the basis of the sampled values, for the detected light signal, wherein the evaluation circuit unit of the distance meter is designed so that the distance to the target object—depending on the activation of the detector, which is caused by the returning light signal, in its middle and upper amplitude range or in its lower, linear amplitude range—is determinable on the basis of the digital data generated in the first channel or on the basis of the digital WFD data.

23 . A distance meter according to any one of claim 19 , wherein:
the detector is designed as a receiver photodiode having a downstream amplifier stage, and having a low-noise trans-impedance amplifier element TIA.

24 . A distance meter according to any one of claim 19 , wherein:
the evaluation circuit unit comprises an FPGA.

25 . A distance meter according to any one of claim 19 , wherein:
the evaluation circuit unit comprises a microprocessor.

26 . A distance meter according to any one of claim 19 , wherein:
the evaluation circuit unit comprises a DSP.

27 . A distance meter according to any one of claim 19 , wherein:
an electronically adjustable damping element VGA is directly upstream of the comparator circuit stage of the time measurement circuit, wherein the damping is dynamically adaptable by the evaluation unit, optionally the FPGA.

28 . A distance meter according to any one of claim 19 , wherein:
the distance meter and the evaluation circuit unit of the distance meter are designed for progressive determination, which is performed in real time, of distances, wherein the evaluation circuit unit is designed to output the distance.

29 . A distance meter according to any one of claim 19 , wherein:
the distance meter and the evaluation circuit unit of the distance meter are designed for progressive determination, which is performed in real time, of distances, wherein the evaluation circuit unit is designed to output the distance, together with a derived amplitude for the returning light signal and a derived quality specification about the distance determination, at a rate in the range of 0.1 to 100 MHz.

30 . Time measurement method for an incoming signal, the method comprising:
progressive checking of a fulfillment of a defined criterion by the incoming signal and outputting a trigger signal upon fulfilling the criterion, wherein exceeding or falling below a threshold value is defined as the criterion, generating and outputting an artificial shape signal in a chronologically fixed manner depending o

Assignees

• Hexagon Technology Ct Gmbh

Inventors

• Stutz Reto
• Bestler Simon
• Wohlgenannt Rainer
• Hinderling Jürg

Classifications

• G01S17/10 Primary

  using transmission of interrupted, pulse-modulated waves (determination of distance by phase measurements G01S17/32) · CPC title

• G04F10/10

  by measuring electric or magnetic quantities changing in proportion to time · CPC title

• G01S17/08 Primary

  for measuring distance only (indirect measurement G01S17/46; active triangulation systems G01S17/48) · CPC title

• G01S17/894

  Three-dimensional [3D] imaging with simultaneous measurement of time-of-flight at a two-dimensional [2D] array of receiver pixels, e.g. time-of-flight cameras or flash lidar · CPC title

• G01S7/4865

  Time delay measurement, e.g. time-of-flight measurement, time of arrival measurement or determining the exact position of a peak (peak detection in noise, signal conditioning G01S7/487) · CPC title