Device for monitoring at least one three-dimensional safety area

1. A device for monitoring at least one three-dimensional safety area, said device comprising at least one capturing device that is pointed at a monitored area enclosing the safety area and captures images of the safety area, and comprising an evaluation device for evaluating the images captured by the capturing device in order to determine whether people or objects have entered the safety area,

wherein at least one projector is arranged with respect to the monitored area in such a way that it projects lines or patterns defining the safety area in the form of modulated light at a predefined on and off frequency, whereby the lines or patterns are alternately projected and not projected depending on the predefined on and off frequency and wherein the evaluation device evaluates the images with regard to configuration of the projected lines or patterns,

wherein the at least one capturing device is synchronized to the predefined on and off frequency to alternately capture images with and without projected lines or patterns and the evaluation device is configured to extract, from successive images with and without projected lines or patterns captured by the at least one capturing device, the configuration of the safety area as a binary current image and to compare the binary current image with a binary target image of the projected safety area determined for the at least one capturing device, the evaluation device being further configured to determine the binary target image as a virtual target image based on intrinsic and extrinsic parameters of the at least one capturing device and the projector and based on the configuration of the known safety area defined by the projected lines or patterns.

2. The device according to claim 1 , wherein the at least one projector and the at least one capturing device are designed to create, alternately, an image of the monitored area with projected safety area and an image of the monitored area without projected safety area.

3. The device according to claim 1 , wherein the binary current image can be determined by addition and subtraction of the successive images of the monitored area, with and without projected safety area, and a breach of the safety area can be determined by addition and subtraction of the binary current image and of the binary virtual target image.

4. The device according to claim 1 , wherein the light projected by the at least one projector is modulated in terms of brightness, preferably pulsed at the predefined frequency, and/or in terms of colour.

5. The device according to claim 1 , wherein the lines or patterns are formed as linear borders of the safety area projected by the at least one projector.

6. The device according to claim 1 , wherein the lines or patterns are variable over time and/or in terms of their form and/or in terms of their presentation.

7. The device according to claim 1 , wherein, in addition to the lines or patterns defining the safety area, the at least one projector is designed to project information in the form of a light script or in the form of light pictograms.

8. The device according to claim 1 , wherein the at least one projector projects a plurality of safety areas, which are nested one inside the other or intersect one another.

9. The device according to claim 1 , wherein the light of the at least one projector lies in the infrared range.

10. The device according to claim 1 , wherein a plurality of capturing devices and/or projectors are arranged above the at least one safety area.

11. The device according to claim 1 , wherein the capturing device(s) and/or the projector(s) are calibrated extrinsically.

12. The device according to claim 1 , wherein the evaluation device is designed to determine a defect of the at least one projector, the at least one capturing device and/or an incorrect alignment of the projector and/or the capturing device when the safety area is not breached by people and/or objects.