Light grid

Patent metadata

Field	Value
Publication number	US-10126416-B2
Application number	US-201615141940-A
Country	US
Kind code	B2
Filing date	Apr 29, 2016
Priority date	May 5, 2015
Publication date	Nov 13, 2018
Grant date	Nov 13, 2018

Abstract

A light grid in accordance with the time of flight principle having at least one light transmitter (2) which transmits light signals (3) into a measured zone (5) and having at least one light receiver (4) which receives the light signals (3) reflected from the measured zone (5) and supplies them in the form of received electrical signals to a control and evaluation unit (7) which determines a distance signal representative of the distance (8) of objects (6) from the light grid (1) from the time between the transmission and the reception of the light signal (3) while taking account of the speed of light, with the light receiver (4) having at least one single photon avalanche diode (9).

First claim

The invention claimed is:

1. A light grid in accordance with the time of flight principle, comprising:
a plurality of light scanners arranged in a housing with each light scanner comprising at least one light transmitter and at least one light receiver, the plurality of light scanners being arrayed and linearly aligned, wherein the at least one light transmitter is positioned within a first housing chamber and the at least one light receiver is positioned within a second housing chamber, the first and second housing chambers being optically isolated from one another such that the at least one light receiver does not receive unreflected portions of light signals transmitted by the at least one light transmitter; and
a further light receiver as a reference light receiver as a second reception channel for a safety-relevant self-test, wherein the reference light receiver is positioned within the first housing chamber,
wherein the at least one light transmitter is configured to transmit the light signals into a measured zone,
wherein the at least one light receiver is configured to receive the light signals reflected from the measured zone, and is further configured to supply the light signals in the form of received electrical signals to a control and evaluation unit,
wherein the control and evaluation unit is configured to determine a distance signal representative of a distance of objects from the light grid from a time between transmission and reception of the light signals while taking account of the speed of light, and
wherein the light receiver has at least one single photon avalanche diode.

2. The light grid in accordance with claim 1 , further comprising a reference surface, with the light signals of the light transmitter being incident on the reference surface and the reflected light signals being incident on the light receiver.

3. The light grid in accordance with claim 1 , further comprising a retroreflector surface, with the light signals of the light transmitter being incident on the retroreflector surface and the reflected light signals being incident on the light receiver.

4. The light grid in accordance with claim 1 , wherein the at least one light receiver comprises a first light receiver and the at least one light transmitter comprises first and second light transmitters, the first light receiver and the first light transmitter forming a first light scanner, and the first light receiver and the second light transmitter forming a second light scanner, with the first light transmitter and the second light transmitter being activated one after the other.

5. The light grid in accordance with claim 1 , wherein the at least one light receiver comprises first and second light receivers, and the at least one light transmitter comprises a first light transmitter, the first light receiver and the first light transmitter forming a first light scanner, and the second light receiver and the first light transmitter forming a second light scanner.

6. The light grid in accordance with claim 1 , wherein a plurality of non-adjacent light transmitters can be activated simultaneously.

7. The light grid in accordance with claim 1 , wherein different light transmitters have different pulse repetition frequencies, modulation frequencies or different phases.

8. The light grid in accordance with claim 1 , wherein the light receiver has at least one array comprising single photon avalanche diodes.

9. The light grid in accordance with claim 1 , further comprising transmission optics arranged in front of the light transmitter.

10. The light grid in accordance with claim 9 , wherein the transmission optics is a lens.

11. The light grid in accordance with claim 1 , further comprising reception optics arranged in front of the light receiver.

12. The light grid in accordance with claim 11 , wherein the reception optics is a lens.

13. The light grid in accordance with claim 1 , further comprising a further light transmitter as a reference light transmitter for a safety-relevant self-test.

14. The light grid in accordance with claim 1 , wherein the control and evaluation unit is configured with two channels.

15. The light grid in accordance with claim 1 , further comprising a positional sensor for evaluating the sensor position of the light grid.

16. The light grid in accordance with claim 13 , wherein the reference light transmitter is positioned within the second housing chamber.

Assignees

• Sick Ag

Inventors

• Albert Magnus
• Sigmund Jörg

Classifications

• G01S7/4861

  Circuits for detection, sampling, integration or read-out · CPC title

• G01S7/4972 Primary

  Alignment of sensor · CPC title

• F16P3/144 Primary

  using light grids · CPC title

• G01S17/10

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