Device for monitoring spatial areas

• US 7,274,438 B2
• Filed: 12/19/2002
• Issued: 09/25/2007
• Est. Priority Date: 12/21/2001
• Status: Active Grant

• Current Assignee: Rockwell Automation, Inc.
• Original Assignee: Siemens AG
• Inventors: Mengel, Peter, Doemens, Günter
• Primary Examiner(s): Tarcza; Thomas H.
• Assistant Examiner(s): Ratcliffe; Luke D.
• Application Number:
  US10/499,668
• Publication Number:
  US 20050078297A1
• Time in Patent Office: 1,741 Days
• Field of Search: 356/5.04
• US Class Current: 356/5.04
• CPC Class Codes: G01S 17/04 Systems determining the presence of a target
• CPC Class Codes: G01S 17/10 using transmission of interrupted, pulse-modulated waves determination of distance by phase measurements G01S17/32
• 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

Abstract

A monitoring device (1) for spatial areas (2) includes emitters (3) that emit radiation pulses that are reflected by objects located within the spatial areas (2) toward receivers (4). The receivers (4) are connected to a run time determining unit (9) with whose aid a distance image of an object within the spatial areas (2) can be generated. A selection unit (10) evaluates the distance images and generates a detection signal at an output (11) when predetermined distance values occur in the distance images.

Claims

1. A monitoring device that produces a light curtain for monitoring spatial areas (2), comprising:

a combination of at least one emitter (3) for emitting radiation pulses into an area and at least one receiver (4) for receiving emitted radiation as reflected from an object within the area,

the emitted radiation pulses forming a reflectorless light curtain,

said at least one receiver having a semiconductor sensor (7) with a plurality of light-sensitive elements (6) with short-time integration for mapping a predefined spatial area (2) within the area into which the radiation pulses are emitted;

wherein,

the spatial area is defined by a predefined distance value range,

said at least one emitter and said at least one receiver are located on a same side of the spatial area,

the at least one receiver (4) is connected to an evaluation unit, the evaluation unit comprising a runtime determining unit (9) connected to said plurality of light-sensitive elements (6),

said runtime determining unit (9)

generates a distance image of the object based on a measuring runtime (T) of the radiation pulses emitted from the emitter (3) to the object and reflected back to the elements (6) of the sensor (7) and calculating a distance value of the object from the receiver (4), and

determines whether the monitored object is one of i) in front of the spatial area (2) and ii) behind the spatial area (2) based on a comparison of the calculated distance value to the predefined distance value range,

wherein said emitter and said receiver are reflectorless and the device is free of any reflectors.

2. The monitoring device that produces a light curtain for monitoring spatial areas (2) according to claim 1, wherein distance images of objects are determined using a plurality of the distance values.

3. The monitoring device that produces a light curtain for monitoring spatial areas (2) according to claim 1, wherein each said receiver (4) comprises a field of the light-sensitive elements (6).

4. The monitoring device that produces a light curtain for monitoring spatial areas (2) according to claim 1, wherein each said receiver (4) comprises a plurality of the light-sensitive elements (6) arranged in a row.

5. The monitoring device that produces a light curtain for monitoring spatial areas (2) according to claim 1, wherein the light-sensitive elements (6) are integrated on a semiconductor chip.

6. The monitoring device that produces a light curtain for monitoring spatial areas (2) according to claim 1, wherein the runtime determining unit (9) is integrated together with the light-sensitive elements (6) in a semiconductor chip.

7. The monitoring device that produces a light curtain for monitoring spatial areas (2) according to claim 1, wherein said evaluation unit further comprises a selection unit (10) that verifies runtime values determined by said runtime determining unit for correspondence with a predefinable profile.

8. The monitoring device that produces a light curtain for monitoring spatial areas (2) according to claim 1, wherein the light curtain is arranged and adapted for counting objects, and wherein the light curtain is located in an area of users (16, 17, 21) whose arrival in the spatial area (2) to be monitored triggers a count signal at the output of the evaluation unit.

9. The monitoring device that produces a light curtain for monitoring spatial areas (2) according to claim 8, wherein the light curtain is arranged and adapted for counting people.

13. The device of claim 1, wherein there is exactly one emitter (3) and one receiver (4), and the entire device is reflectorless.

10. A monitoring device that produces a light curtain for monitoring a spatial area (2), comprising:

an infrared wavelength radiation pulse emitter (3) configured to emit infrared wavelength radiation pulses to form a reflectorless light curtain covering a predefined spatial area, the spatial area being defined by a predefined distance value range;

a receiver (4) configured to receive the radiation pulses as reflected back from an object,

the emitter and receiver being on a same side of the spatial area,

the receiver comprising an optical system (5) that maps the received reflected radiation pulses onto pixels (6) of a sensor (7) so that the pixels'"'"' exposure to the received reflected radiation pulses charges each pixel to measure a quantity of radiation energy acquired by each pixel; and

a runtime determining unit (9) connected to the pixels and configured i) to calculate a distance value of the object from the receiver, and ii) using the distance value, to determine whether the object is outside the spatial area, wherein,

generating the distance value comprises

emitting a first radiation pulse from the emitter and activating the pixels for a first time interval (t1) to measure a first exposure to the pixels of the first radiation pulse, and

emitting a second radiation pulse from the emitter and activating the pixels for a second time interval (t2) to measure a second exposure to the pixels of the second radiation pulse, the first and second time intervals being of different durations, the first and second exposure measurements at each pixel determining a runtime (T) of the radiation pulses from the emitter to the object and back to each pixel, and

using the determining runtime in calculating the distance value of the object from the receiver, the distance value being used to determine whether the object is outside the spatial area, the calculated distance value being outside the predefined distance value range corresponding to the spatial area indicating the object being outside the spatial area,

wherein the emitter and the receiver are reflectorless and the device is free of any reflectors.

11. The monitoring device that produces a light curtain for monitoring a spatial area (2), of claim 10 further comprising:

a selection unit (10) connected to the runtime determining unit and configured to detect the object being in the spatial area based on the distance value received from the runtime determining unit being with a value range corresponding to the spatial area, the selection unit emitting a detection signal at an output (11) upon the detection of the object in the spatial area, wherein,

a restriction to predefined distance values prevents the selection unit emitting the detection signal at the output when the runtime determining unit determines the object is outside the spatial area.

12. A monitoring device that produces a light curtain for monitoring a spatial area (2), comprising:

a radiation pulse emitter (3) configured to form a reflectorless light curtain covering a predefined spatial area by emitting radiation pulses;

a receiver (4) configured to receive radiation pulses as reflected back from an object,

the emitter and receiver being on a same side of the spatial area,

the receiver comprising an optical system (5) that maps the received reflected radiation pulses onto pixels (6) of a sensor (7); and

a runtime determining unit (9) connected to the pixels and configured to

determine that a first object is outside the spatial area upon receiving radiation pulses reflected from the first object located outside the spatial area, and

issue a detection signal upon receiving radiation pulses reflected from objects located inside the spatial area, wherein,

the runtime determining unit calculates a distance value of the first object from the receiver, and uses the calculated distance value to determine that the first object is outside the spatial area,

calculating the distance value comprises emitting first and second radiation pulses, of different time durations, from the emitter and measuring corresponding respective radiation exposures at one pixel of the pixels to determining a runtime (1) of the first and second radiation pulses from the emitter to the first object and back to the one pixel, and using the determined runtime to calculate the distance value of the first object from the receiver, the calculated distance value being outside a predefined distance value range corresponding to the spatial area indicating the first object being outside the spatial area,

wherein the emitter and the receiver are reflectorless and the device is free of any reflectors.