METHOD AND TIME-OF-FLIGHT CAMERA FOR PROVIDING DISTANCE INFORMATION

• US 20140160461A1
• Filed: 07/12/2012
• Published: 06/12/2014
• Est. Priority Date: 07/15/2011
• Status: Active Grant

• Current Assignee: Softkinetic Sensors NV (Sony Group Corp.)
• Original Assignee: Softkinetic Sensors NV (Sony Group Corp.)
• Inventors: Van Der Tempel, Ward, Grootjans, Riemer
• Granted Patent: US 9,599,712 B2
• Time in Patent Office: Days
• US Class Current: 356/5.01
• 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 7/484 Transmitters
• CPC Class Codes: G01S 7/4865 Time delay measurement, e.g. time-of-flight measurement, time of arrival measurement or determining the exact position of a peak peak detection in noise, signal conditioning G01S7/487
• CPC Class Codes: G01S 7/487 Extracting wanted echo signals , e.g. pulse detection
• CPC Class Codes: G05D 13/08 without auxiliary power

Abstract

The invention relates to a method for providing distance information of a scene with a time-of-flight camera (1), comprising the steps of emitting a modulated light pulse towards the scene, receiving reflections of the modulated light pulse from the scene, evaluating a time-of-flight information for the received reflections of the modulated light pulse, and deriving distance information from the time-of-flight information for the received reflections, whereby a spread spectrum signal is applied to a base frequency of the modulation of the light pulse, and the time-of-flight information is evaluated under consideration of the a spread spectrum signal applied to the base frequency of the modulation of the light pulse. The invention further relates to a time-of-flight camera (1) for providing distance information from a scene, whereby the time-of-flight camera (1) performs the above method.

Claims

1. A method for providing distance information of a scene with a time-of-flight sensor or camera (1), comprising the steps of

emitting a periodic light signal towards the scene in accordance with a modulation signal based on a clock timing that has a base frequency spread by a periodic perturbation with a perturbation frequency and period,

receiving reflections of the periodic light signal from the scene,

evaluating a time-of-flight information for the received reflections of the periodic light signal over a set of a plurality of measurement durations in accordance with the modulation signal, and

deriving distance information from the time-of-flight information for the received reflections, wherein each measurement duration of the set is an integer or half integer multiple of the perturbation period and over the set of measurement durations the average base frequency is kept constant.

28. Method according to claim 1, wherein the modulation signal taken over one measurement duration of the set has the same spectral content as the modulation signal taken over any other measurement duration of the set.

29. Method according to claim 1, wherein the step of evaluating a time-of-flight information for the received reflections of the periodic light signal comprises integrating the received reflections of the periodic light signal over each of the plurality of measurements of the set, and combining the results.

30. Method according to claim 1, wherein a discontinuous perturbation modulation is applied.

31. Method according to claim 1, further comprising dynamically increasing or decreasing the perturbation frequency.

32. Method according to claim 1, further comprising lowering the power of the periodic light signal and reducing the perturbation frequency.

33. The method of claim 1, wherein, the periodic light signal is a pulsed or sinusoidal signal.

34. Method according to claim 1, wherein the perturbation frequency is within an interval of the base frequency, preferably within an interval +/−

5% or +/−

1.5% of the base frequency, or within an interval +/−

0.1% of the base frequency of the modulation signal.

2-27. -27. (canceled)

35. A range finding device for providing distance information from a scene, the range finding device being for use with a light source for emitting a periodic light signal towards the scene, the range finding device comprising:

a modulation unit (3) for providing a modulation signal for the light source based on a clock timing with a base frequency spread by a periodic perturbation with a perturbation frequency and period,

a reception group (6) with a receiver unit (7), an evaluation unit (8) and a processing unit (9), the reception group (6) being connected to the modulation unit to receive the modulation signal,

the evaluation unit (8) being adapted to evaluate time-of-flight information from received reflections from the scene over a set of a plurality of measurement durations in accordance with the clock timing that is spread by the periodic perturbation,

the calculation unit (9) being adapted to derive distance information from the time-of-flight information provided by the evaluation unit (8) wherein each measurement duration of the set is an integer or half integer multiple of the perturbation period and over the set of measurement durations the average base frequency is kept constant.

36. A range finding device according to claim 35, further arranged for providing said distance information from a scene according a method for providing distance information of a scene with a time-of-flight sensor or camera (1), wherein said device performs a method comprising:

emitting a periodic light signal towards the scene in accordance with a modulation signal based on a clock timing that has a base frequency spread by a periodic perturbation with a perturbation frequency and period,

receiving reflections of the periodic light signal from the scene,

evaluating a time-of-flight information for the received reflections of the periodic light signal over a set of a plurality of measurement durations in accordance with the modulation signal, and

deriving distance information from the time-of-flight information for the received reflections, wherein each measurement duration of the set is an integer or half integer multiple of the perturbation period and over the set of measurement durations the average base frequency is kept constant.

37. A timing module for time-of-flight sensor for use with a light source for emitting periodic light signal towards a scene, the sensor being for providing distance information from a scene, the timing module comprising:

a modulation unit (3) for providing a modulation signal for the light source having a clock timing with a base frequency spread by a periodic perturbation with a perturbation frequency and period,

the modulation unit being adapted to provide the modulation signal over a set of a plurality of measurement durations in accordance with the clock timing that is spread by the periodic perturbation,

wherein each measurement duration of the set is an integer or half integer multiple of the perturbation period and over the set of measurement durations the average base frequency is kept constant.