Optical distance measuring device and method for optical distance measurement

Patent metadata

Field	Value
Publication number	US-10101155-B2
Application number	US-201615211847-A
Country	US
Kind code	B2
Filing date	Jul 15, 2016
Priority date	Apr 14, 2008
Publication date	Oct 16, 2018
Grant date	Oct 16, 2018

Abstract

The present invention describes an optical distance measuring device having a pulsed radiation source that is implemented to transmit, in a temporally contiguous radiation pulse period, a radiation pulse having a pulse duration t p that is shorter than the radiation pulse period, and to transmit no radiation pulse in a temporally contiguous dark period. Further, the optical distance measuring device includes a detector for detecting different amounts of radiation in two overlapping detection periods during the radiation pulse period to capture reflections of the radiation pulse at an object surface and a background radiation and/or in two overlapping detection periods during the dark period to capture background radiation. The optical distance measuring device further includes an evaluator determining a signal depending on a distance of the optical distance measuring device to an object based on the detected amount of radiation. Further, the present invention provides a method for optical distance measurement and for multiple sampling.

First claim

The invention claimed is:

1. An apparatus comprising:
a capacitive pixel sensor element subjected to a charge or discharge process in dependence on a measured quantity that can be detected at a pixel sensor element output;
at least one buffer amplifier;
first and second sample capacitances;
first and second switches, via which the first or the second sample capacitance can be connected to the pixel sensor element output via the at least one buffer amplifier;
a controller that is implemented to control the first and second switches such that the first switch is closed in a first time window and the second switch is closed in a second time window, wherein the first time window and the second time window temporally overlap such that, at the end of the first and second time windows, different voltage signals describing the charge or discharge process of the capacitive pixel sensor element are applied to the first and second sample capacitances;
an evaluator determining a differential voltage signal based on voltage signals applied successively to the first and second sample capacitances;
wherein the evaluator further comprises an amplifier, wherein the output of the amplifier can be connected to an input via a reset switch;
a sample capacitance that can be electrically coupled to the first and second sample capacitances via a switch and that can be connected to the input of the amplifier;
first and second feedback capacitances connected in parallel that can be coupled to the input of the amplifier and can be connected to a reference potential via a reference voltage switch and to the output of the amplifier via first and second amplifier switches; and wherein the controller is implemented to control the evaluator such that differential voltage signals of the voltage signals applied to the input are available at the output of the evaluator in successive time phases.

2. The apparatus according to claim 1 , wherein the voltage signals describing the charge or discharge process of the capacitive pixel sensor element can be digitalized on-chip at the first and second sample capacitances, and a subtraction or division of the digitalized voltage signals can be performed on-chip for determining a distance value to an object.

3. The apparatus according to claim 1 , wherein the measured quantity is a pulsed radiation.

4. The apparatus according to claim 1 , wherein the pixel sensor element is implemented as PN diode, photogate, charged-coupled device (CCD), PIN diode, CCD photogate, photonic mixer, N-well photodiode or as pinned photodiode.

5. The apparatus according to claim 1 , wherein the pixel sensor element is implemented such that the charge or discharge process is performed based on a radiation interacting with the capacitive pixel sensor element.

6. The apparatus according to claim 1 , wherein the controller is implemented such that the first switch is closed for the first time window and the second switch for the second window with an adjustable known time offset at the begin of the charge or discharge process in dependence on the measured quantity, wherein the duration of the first time window is shorter than the duration of the second time window.

7. The apparatus according to claim 1 , wherein the first time window is closed during an interaction period of the measured quantity in dependence on which the capacitive pixel sensor element performs the charge or discharge process.

Assignees

• Volkswagen Ag

Inventors

• Schrey Olaf
• Brockherde Werner
• Hosticka Bedrich
• Ulfig Wiebke

Classifications

• 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

• G01C3/08 Primary

  Use of electric radiation detectors · CPC title

• G01S17/18

  wherein range gates are used · CPC title

• G01S7/487 Primary

  Extracting wanted echo signals {, e.g. pulse detection} · CPC title

• G01S17/107

  Physics · mapped topic