Optoelectronic apparatus and method of operating the optoelectronic apparatus in order to detect an object

• US 7,391,007 B2
• Filed: 12/11/2006
• Issued: 06/24/2008
• Est. Priority Date: 12/16/2005
• Status: Active Grant

• Current Assignee: Sick AG (Sick)
• Original Assignee: Sick AG (Sick)
• Inventors: Waslowski, Kai-Jürgen, Blümcke, Thomas, Zipfel, Steffen, Hörsch, Ingolf, Jaksic, Davorin
• Primary Examiner(s): Epps; Georgia Y.
• Assistant Examiner(s): Legasse, Jr.; Francis M
• Application Number:
  US11/637,229
• Publication Number:
  US 20070145272A1
• Time in Patent Office: 561 Days
• Field of Search: 250/221, 250/222.1, 250/224, 250/208.2, 340555-557
• US Class Current: 250/221
• CPC Class Codes: G01V 8/22 using reflectors

Abstract

A method for the detection of an object includes transmitting light in the direction of a reflector by a transmitter. The transmitted light is reflected by the reflector and is imaged as a reflector image and is detected by the receiver. The reflector image is evaluated and an object detection signal is generated if an at least partial interruption of the transmitted light is recognized. A light object incident onto the receiver outside the detection region is detected by the receiver, is examined for predetermined object properties and is classified as a reflector image or as an interfering light object based on the object properties. In the case of a classification as an interfering light object, a movement of the interfering light object on the receiver is determined and the generation of the object detection signal is executed based on the determined movement of the interfering light object.

Claims

1. A method for the detection of an object, comprising:

transmitting light in the direction of a reflector (2) using a transmitter (1);

reflecting the transmitted light at the reflector (2);

imaging the reflected transmitted light as a reflector image (11) on a detection region of a receiver (9) with at least one-dimensional spatial resolution, wherein the reflector image is detected by said receiver;

evaluating the detected reflector image;

generating an object detection signal when an at least partial interruption of the transmitted light is recognized based on the evaluation of the detected reflector image;

detecting a light object incident onto the receiver (9) outside of a detection region (23) using said receiver;

examining the light object for predetermined object properties;

classifying the light object as one of a reflector image and an interfering light object based on the object properties determined; and

in the case of a classification as an interfering light object, determining a movement of the interfering light object on the receiver (9), wherein the generation of the object detection signal is carried out in dependence on the determined movement of the interfering light object.

2. A method in accordance with claim 1, wherein a predefined region of the receiver forms the detection region.

3. A method in accordance with claim 1, wherein in the case of a classification of the light object as a reflector image, the region of the receiver acted on by the reflector image is fixed as the detection region.

4. A method in accordance with claim 1, wherein the evaluation of the reflector image (11) is interrupted when an impending overlap or a present—

at least part—

overlap of the interfering light object (20) with the detection region is recognized based on the determined movement of the interfering light object.

5. A method in accordance with claim 4, wherein an object detection state characterized by the object detection signal before the interruption of the evaluation of the reflector image (11) is maintained during the interruption.

6. A method in accordance with claim 1, wherein, on the evaluation of the reflector image (11), a brightness of the interfering light object (20) to be expected is subtracted from the brightness detected in the detection region (23) when an impending overlap or a present—

at least part—

overlap of the interfering light object (20) with the detection region (23) is recognized based on the detected movement of the interfering light object (20), with the brightness of the interfering light object (20) to be expected being determined from the brightness of the interfering light object (20) before reaching the detection region (23).

7. A method in accordance with claim 4, wherein an impending overlap of the interfering light object (20) with the detection region (23) is recognized when, with an assumed unchanging movement of the interfering light object (20), the latter would be incident at least partly into the detection region (23) after a predetermined number of evaluation intervals.

8. A method in accordance with claim 1, wherein the movement of the interfering light object (20) is determined by detection of the respective position of the interfering light object (20) in time sequential evaluation intervals.

9. A method in accordance with claim 1, wherein at least one of a position on the receiver, a light intensity, a shape, a direction of movement, a speed of movement, and a wavelength of the light object is determined as an object property.

10. A method in accordance with claim 1, wherein the transmitted light is provided with a code, for example by one of an encoded reflector and filter, and the light object is examined for the presence of this code for the determination of the object properties.

11. A method in accordance with claim 1, wherein pulsed light is used, and wherein the light object is examined for the presence of the pulse frequency used for the determination of the object property.

12. A method in accordance with claim 1, wherein a receiver with two dimensional spatial resolution is used as the receiver (9).

13. A method in accordance with claim 1, wherein the object detection signal is generated when the actual brightness of the detected reflector image (11) falls below a predetermined brightness to be expected on the lack of an object.

14. A method in accordance with claim 1, wherein a light object incident onto the receiver (9) inside the detection region (23) is also detected by said receiver, is examined for predetermined object properties and is classified as a reflector image or as an interfering light object based on the object properties determined.

15. A method in accordance with claim 1, wherein at least one of an angle of deviation of the transmitter (1), which is defined as an angle between the optical axis of the transmitter (1) and the optical axis of an optical element (5) imaging the transmitted light onto the reflector (2), and an angle of deviation of the receiver (9), which is defined as an angle between the optical axis of the receiver (9) and the optical axis of an optical element (8) imaging the reflected light onto the receiver (9), is compensated by taking account of the position of the reflector image (11) and/or of the interfering light object (20) on the receiver (9).

16. An apparatus for the detection of an object (13), comprising:

a transmitter (1) transmitting light;

a reflector (2) reflecting the transmitted light;

a receiver (9) with at least one dimensional spatial resolution and having a detection region (23), said receiver being arranged and made for the detection of a reflector image (11) imaged on the receiver (9) by the light reflected by the reflector (2);

an evaluation unit (10) made for the evaluation of the detected reflector image and for the generation of an object detection signal when an at least partial interruption of the transmitted light can be recognized based on the evaluation of the detected reflector image (11),

wherein said evaluation unit comprises;

a classification unit (24) that is provided for the examination of an interfering light object incident onto the receiver (9) outside of a detection region and detected by said receiver for predetermined object properties and for the classification of the light object as one of a reflector image and an interfering light object based on the determined object properties and

a movement detection unit (25) that is provided for the detection of the movement of an interfering light object on the receiver, wherein the evaluation unit (10) is made for the generation of the object detection signal in dependence on the detected movement of the interfering light object.

17. An apparatus in accordance with claim 16, wherein the sensor (9) is made as a sensor with two dimensional spatial resolution.

18. An apparatus in accordance with claim 16, wherein the evaluation unit (10) is made to interrupt the evaluation of the reflector image (20) when one of an impending overlap and a present, at least partial overlap of the interfering light object (20) with the detection region (23) can be recognized based on the movement of the interfering light object (20) detected by the movement detection unit (25).

19. An apparatus in accordance with claim 16, wherein the evaluation unit (10) is made to generate an object detection signal upon the evaluation of the reflector image (11), even when a predetermined brightness of the reflector image (11) to be expected is exceeded by the actual brightness of the detected reflector image (11) if one of an impending overlap and a present, at least partial overlap of the interfering light object (20) with the detection region (23) is recognized based on the movement of the interfering light object (20) detected.

20. An apparatus in accordance with claim 19, wherein said evaluation unit (10) further comprises a subtraction unit (26) with which, on the evaluation of the reflector image (11), a brightness of the interfering light object (20) to be expected is subtracted from the brightness detected in the detection region (23) when an impending, at least part overlap of the interfering light object (20) with the detection region (23) is recognized based on the detected movement of the interfering light object (20), and wherein the evaluation unit (10) is made for the determination of the brightness of the interfering light object (20) to be expected from the brightness of the interfering light object (20) before reaching the detection region (23).