Monitoring method and optoelectronic sensor

• US 20030075675A1
• Filed: 09/04/2002
• Published: 04/24/2003
• Est. Priority Date: 09/05/2001
• Status: Active Grant

• Current Assignee: Sick AG (Sick)
• Original Assignee: Sick AG (Sick)
• Inventors: Henkel, Olaf, Braune, Ingolf
• Granted Patent: US 6,940,060 B2
• Time in Patent Office: Days
• US Class Current: 250/221
• CPC Class Codes: G01S 17/04 Systems determining the presence of a target
• CPC Class Codes: G01S 17/89 for mapping or imaging
• CPC Class Codes: G01S 7/4802 using analysis of echo signal for target characterisation; Target signature; Target cross-section
• CPC Class Codes: G01S 7/497 Means for monitoring or calibrating
• CPC Class Codes: G08B 13/194 using image scanning and comparing systems

Abstract

The invention relates to a method of monitoring a monitored zone by means of an optoelectronic sensor, wherein transmitted light is transmitted in accordance with a structured light pattern in the direction of the monitored zone and is received from the monitored zone, the received light is converted into received signals and the received signals are evaluated with respect to the presence of an object, or with respect to a movement of an object, in the monitored zone. The transmitted light is transmitted and/or received in accordance with at least two different light patterns. The invention further relates to an optoelectronic sensor.

Claims

1. A method of monitoring a monitored zone (49) by means of an opto-electronic sensor (33), wherein

in accordance with a structured light pattern, transmitted light is transmitted in the direction of the monitored zone (49) and is received from the monitored zone;

the received light is converted into received signals; and

the received signals are evaluated with respect to the presence of an object (53), or with respect to a movement of an object (53), in the monitored zone (49),

characterized in that the transmitted light is transmitted and/or received in accordance with at least two different light patterns.

2. A method in accordance with claim 1, characterized in that the light patterns are structured in a complementary manner to one another, at least in part and preferably fully.

3. A method in accordance with claim 1, characterized in that the light patterns have a regular structure, with the light patterns in particular being equi-distantly alternating patterns;

or in that the light patterns have an irregular structure.

4. A method in accordance with claim 1, characterized in that the light patterns are phase-shifted by 180°

with respect to one another.

5. A method in accordance with claim 1, characterized in that the light patterns are linear or of matrix shape.

6. A method in accordance with claim 1, characterized in that the light patterns are light/dark patterns, with the transitions between light and dark regions being in particular continuous or discontinuous.

7. A method in accordance with claim 1, characterized in that the transmitted light is transmitted and/or received alternately in accordance with the at least two different light patterns.

8. A method in accordance with claim 1, characterized in that the different light patterns are each produced by an associated transmission device (35, 37).

9. A method in accordance with claim 1, characterized in that the different light patterns are produced by the use of different optical transmission systems (39, 41).

10. A method in accordance with claim 1, characterized in that the different light patterns are produced by the use of different optical reception systems.

11. A method in accordance with claim 1, characterized in that the transmitted light beam and/or a bundle of rays of the received light is deflected, shifted or tilted to produce the different light patterns.

12. A method in accordance with claim 1, characterized in that at least one light pattern is produced by the use of a diffractive optical element (39, 41).

13. A method in accordance with claim 1, characterized in that transmitted light is received and evaluated which has been reflected or remitted from the monitored zone (49), or which has substantially passed through the monitored zone in a straight line.

14. A method in accordance with claim 1, characterized in that the transmitted light is transmitted in transmitted pulses, with the reception of the light from the monitored zone (49) preferably taking place in synchronization with the emitting of the transmitted pulses.

15. A method in accordance with claim 1, characterized in that, for the evaluation of the received light, the received signals determined for a specific light pattern, or the data processed from these received signals, are compared with received signals or data which were determined for the same light pattern at a previous time.

16. A method in accordance with claim 15, characterized in that the monitored zone (49) was in a calibration state—

in particular an object-free calibration state—

at the previous time;

or in that the previous time is the time of the directly preceding transmission and/or reception of the same light pattern.

17. A method in accordance with claim 1, characterized in that a test of an error-free reception of light is carried out in that received signals are determined and compared with emitted transmitted light, wherein the reception signals are preferably compared with one another and/or with received signals which are determined when no transmitted light has been transmitted.

18. A method in accordance with claim 17, characterized in that the test is carried out for a plurality of light patterns, in particular for all different light patterns.

19. A method in accordance with claim 17, characterized in that the received signals are compared with one another with respect to a respective one of a plurality of reception elements of the optoelectronic sensor (33);

and/or in that a defective reception is detected if the respective reception signals do not differ from one another or differ from one another by less than a pre-determined threshold.

20. A method in accordance with claim 17, characterized in that the test is carried out before the start of a subsequent monitoring operation of the optoelectronic sensor (33);

and/or in that the test is carried out during a monitoring operation of the optoelectronic sensor (33), in particular at regular intervals.

21. A method in accordance with claim 1, characterized in that the method of securing the monitored zone (49) against unauthorized intervention is used;

and in that a switching off signal or a warning signal is produced if the presence of an object (53), or a movement of an object (53), in the monitored zone (49) was detected as the result of an evaluation of the received signals.

22. A method in accordance with claim 1, characterized in that the received signals are additionally evaluated with respect to the distance of an object (53) located within the monitored zone (49), in particular by taking into account a beam path which diverges due to a triangulation arrangement.

23. An optoelectronic sensor (33) for the monitoring of a monitored zone (49) comprising

at least one transmission device (35, 37) for the transmission of transmitted light in the direction of the monitored zone (49);

at least one reception device (45) for the conversion of light received from the monitored zone (49) into received signals; and

an evaluation device (47) for the evaluation of the received signals with respect to the presence of an object (53), or a movement of an object (53), in the monitored zone (49),

wherein the transmission device (35, 37) and/or the reception device (45) is formed for the transmission or reception of a structured light pattern, and

wherein the sensor (33) is formed in particular for the carrying out of the method in accordance with at least claim 1, characterized in that the at least one transmission device (35, 37) and/or the at least one reception device (45) is formed for the transmission or reception of at least two different light patterns.

24. A sensor in accordance with claim 23, characterized in that the light patterns are structured in a complementary manner to one another, at least in part and preferably fully.

25. A sensor in accordance with claim 23, characterized in that the transmission device (35, 37) and/or the reception device (45) is formed for the alternating transmission or reception, respectively, of the different light patterns.

26. A sensor in accordance with claim 23, characterized in that a respective separate transmission device (35, 37) is provided for the transmission of the different light patterns.

27. A sensor in accordance with claim 23, characterized in that a respective separate optical transmission system (39, 41) is provided for the transmission of the different light patterns.

28. A sensor in accordance with claim 23, characterized in that the reception device (45) has a plurality of reception elements.

29. A sensor in accordance with claim 23, characterized in that a respective separate optical reception system is provided for the reception of the different light patterns.

30. A sensor in accordance with claim 23, characterized in that a movable, in particular a displaceable or tiltable optical transmission system and/or optical reception system is provided.

31. A sensor in accordance with claim 23, characterized in that an optical transmission system and/or an optical reception system has at least one diffractive optical element (39, 41).

32. A sensor in accordance with claim 23, characterized in that the transmission device (35, 37) and the reception device (47) are arranged in a reflection arrangement or in a transmission arrangement.

33. A sensor in accordance with claim 23, characterized in that the received signals which are determined for a specific light pattern can be compared by the evaluation device (47) with received signals which were determined at a previous time for the same light pattern.

34. A sensor in accordance with claim 23, characterized in that, for a test of an error-free reception of light, the received signals which are determined with emitted transmitted light can be compared by the evaluation device (47) with reception signals which are determined when no transmitted light was transmitted.