Time of Flight Camera Unit and Optical Surveillance System

• US 20110254928A1
• Filed: 04/14/2011
• Published: 10/20/2011
• Est. Priority Date: 04/15/2010
• Status: Active Grant

• Current Assignee: Rockwell Automation Switzerland GmbH (Rockwell Automation, Inc.)
• Original Assignee: Rockwell Automation Safety AG (Rockwell Automation, Inc.)
• Inventors: Meinherz, Carl
• Granted Patent: US 8,878,901 B2
• Time in Patent Office: Days
• US Class Current: 348/46
• CPC Class Codes: G01B 11/22 for measuring depth
• CPC Class Codes: G01B 11/24 for measuring contours or curvatures
• CPC Class Codes: G01B 11/245 using a plurality of fixed, simultaneously operating transducers G01B11/2408 - G01B11/2425, G01B11/255 take precedence
• CPC Class Codes: G01S 17/36 with phase comparison between the received signal and the contemporaneously transmitted signal
• CPC Class Codes: G01S 17/42 Simultaneous measurement of distance and other co-ordinates indirect measurement G01S17/46
• CPC Class Codes: G01S 17/87 Combinations of systems using electromagnetic waves other than radio waves
• CPC Class Codes: G01S 17/894 3D imaging with simultaneous measurement of time-of-flight at a 2D array of receiver pixels, e.g. time-of-flight cameras or flash lidar
• CPC Class Codes: G06T 2207/10012 Stereo images
• CPC Class Codes: G06T 2207/30232 Surveillance
• CPC Class Codes: G06T 7/55 from multiple images
• CPC Class Codes: H04N 13/214 using spectral multiplexing

Abstract

A time of flight, TOF, camera unit for an optical surveillance system and an optical surveillance system comprising such a TOF camera is disclosed. The TOF camera unit comprises a radiation emitting unit for illuminating a surveillance area defined by a first plane, a radiation detecting unit for receiving radiation reflected from said surveillance area and for generating a three-dimensional image from said detected radiation, and at least one mirror for at least partly deflecting said emitted radiation into at least one second plane extending across to said first plane and for deflecting the radiation reflected from said second plane to the radiation detecting unit. The TOF camera and the at least one mirror may be ar-ranged on a common carrier element.

Claims

1. A time of flight (TOF) camera unit for an optical surveillance system, said TOF camera unit comprising:

a radiation emitting unit for illuminating a surveillance area defined by a first plane;

a radiation detecting unit for receiving radiation reflected from said surveillance area and for generating a three-dimensional image from said detected radiation;

at least one mirror for at least partly deflecting said emitted radiation into at least one second plane extending across to said first plane and for deflecting the radiation reflected from said second plane to the radiation detecting unit.

2. The TOF camera unit according to claim 1, wherein said radiation emitting unit comprises at least one light emitting diode, LED, and/or infrared radiation emitting diode, IRED.

3. The TOF camera unit according to claim 1, wherein said radiation detecting unit comprises a phase sensitive detector chip and a signal processing unit for evaluating outputs of said detector chips.

4. The TOF camera unit according to claim 3, wherein said signal processing unit is operable to define and evaluate a first depth level representing the area directly illuminated by said radiation emitting unit, and at least one second depth level representing the area illuminated by said radiation emitting unit via said at least one mirror,

wherein said signal processing unit is further operable to combine the images corresponding to the first and second depth levels for generating a three-dimensional image of the total surveillance area.

5. The TOF camera unit according to claim 1, further comprising a carrier element, wherein said at least one mirror is held in a predetermined position with respect to said TOF camera by means of said carrier element.

6. The TOF camera unit according to claim 1, wherein a viewing angle of said radiation detecting unit is larger than needed for monitoring said surveillance area, and wherein said at least one mirror is located in a peripheral region of said viewing angle.

7. The TOF camera unit according to claim 1, wherein an aperture of said radiation emitting unit is larger than needed for illuminating said surveillance area, and wherein said at least one mirror is arranged in a way that it deflects a peripheral portion of the radiation.

8. The TOF camera unit according to claim 1, wherein said radiation emitting unit and said radiation detecting unit are arranged within a common camera housing and wherein a plurality of mirrors is arranged symmetrically around said camera housing.

9. The TOF camera unit according to claim 1, wherein said radiation emitting unit comprises an array of light emitting diodes, LED, and/or infrared radiation emitting diodes, IRED, which are arranged on a non-planar substrate and said radiation detecting unit comprises an array of photonic mixer detectors, PMD, which are arranged on a non-planar substrate.

10. An optical surveillance system comprising:

a time of flight, TOF, camera for three-dimensionally monitoring a surveillance area;

at least one mirror element for deflecting measurement radiation emitted from an emitting unit of the TOF camera to said surveillance area and for deflecting the radiation reflected by the surveillance area to a detector unit of the TOF camera;

a control unit for calculating a three-dimensional image from the radiation received by said detector unit.

11. The optical surveillance system according to claim 10, wherein said control unit is further operable to evaluate said three-dimensional image and to output a safety switching signal in response to a result of the evaluation.

12. The optical surveillance system according to claim 10, wherein said radiation emitting unit comprises at least one light emitting diode, LED, and/or infrared radiation emitting diode, IRED.

13. The optical surveillance system according to claim 10, wherein said radiation detecting unit comprises a phase sensitive detector chip and a signal processing unit for evaluating outputs of said detector chips.

14. The optical surveillance system according to claim 13, wherein said signal processing unit is operable to define and evaluate a first depth level representing the area directly illuminated by said radiation emitting unit, and at least one second depth level representing the area illuminated by said radiation emit-ting unit via said at least one mirror,

wherein said processing unit is further operable to combine the images corresponding to the first and second depth levels for generating a three-dimensional image of the total surveillance area.

15. The optical surveillance system according to claim 10, further comprising a carrier element, wherein said at least one mirror is held in a predetermined position with respect to said TOF camera by means of said carrier element.

16. The optical surveillance system according to claim 10, wherein a viewing angle of said receiving unit is larger than needed for monitoring said surveillance area, and wherein said at least one mirror is located in a peripheral region of said viewing angle.

17. The optical surveillance system according to claim 10, wherein an aperture of said radiation emitting unit is larger than needed for illuminating said surveillance area, and wherein said at least one mirror is arranged in a way that it deflects a peripheral portion of the radiation.

18. The optical surveillance system according to claim 10, wherein said radiation emitting unit and said radiation detecting unit are arranged within a common camera housing and wherein a plurality of mirrors is arranged symmetrically around said camera housing.

19. The optical surveillance system according to claim 10, wherein said radiation emitting unit comprises an array of light emitting diodes, LED, and/or infrared radiation emitting diodes, IRED which are arranged on a non-planar substrate and said radiation detecting unit comprises an array of photonic mixer detectors, PMD, which are arranged on a non-planar substrate.