Time-of-flight distance measuring device and method for detecting multipath error

A time-of-flight distance measuring device comprising:

• a light source that emits light, as emitted light, to illuminate a specified region;
• a light receiver that detects, as reflected light, the emitted light reflected by an object in the specified region;
• a first controller that controls the light source;
• a second controller that controls the light receiver;
• a calculator that calculates a distance to the object based on the reflected light detected by the light receiver;
• and
• a multipath detector that detects occurrence of a multipath error, wherein
• the specified region is divided into a plurality of sub-regions,
• the light source includes a plurality of emitting portions, each of the plurality of emitting portions illuminating a respective one of the plurality of sub-regions,
• the light receiver includes a plurality of receiving portions corresponding to respective ones of the plurality of emitting portions, each of the plurality of receiving portions being spaced away from each other to sense the reflected light reflected from the sub-region illuminated by the corresponding emitting portion,
• the first controller controls,
• at a first timing, (i) a first emitting portion of the plurality of emitting portions to emit the emitted light as an amplitude-modulated waveform including an Nth-order harmonic component of a fundamental frequency and (ii) a second emitting portion of the plurality of emitting portions to emit the emitted light as an amplitude-modulated waveform including an Mth-order harmonic component of the fundamental frequency, wherein N and M are different positive integers, and
• at a second timing, (i) the second emitting portion to emit the emitted light as an amplitude-modulated waveform including the Nth-order harmonic component of the fundamental frequency and (ii) the first emitting portion to emit the emitted light as an amplitude-modulated waveform including the Mth-order harmonic component of the fundamental frequency,
• the second controller controls,
• at the first timing, a first receiving portion of the plurality of receiving portions corresponding to the first emitting portion to be sensible to the Nth-order harmonic component and the Mth-order harmonic component, and
• at the second first timing, a second receiving portion of the plurality of receiving portions corresponding to the second emitting portion to be sensible to the Nth-order harmonic component and the Mth-order harmonic component, and
• the multipath detector detects occurrence of the multipath error when (i) the first receiving portion senses, at the first timing, both the Nth-order component and the Mth-order component or (ii) the second receiving portion senses, at the second timing, both the Nth-order component and the Mth-order component.

A method for detecting a multipath error using a time-of-flight distance measuring technology, comprising:

• controlling, by a first controller, a light source to emit light, as emitted light, to illuminate a specified region;
• controlling, by a second controller, a light receiver to detect, as detected light, the emitted light reflected by an object in the specified region;
• calculating, by a calculator, a distance to the object based on the reflected light detected by the light receiver;
• and
• detecting, by a multipath detector, occurrence of a multipath error, wherein
• the specified region is divided into a plurality of sub-regions,
• the light source includes a plurality of emitting portions, each of the plurality of emitting portions illuminating a respective one of the plurality of sub-regions,
• the light receiver includes a plurality of receiving portions corresponding to respective ones of the plurality of emitting portions, each of the plurality of receiving portions being spaced away from each other to sense the reflected light reflected from the sub-region illuminated by the corresponding emitting portion,
• the first controller controls (i) a first emitting portion of the plurality of emitting portions to emit the emitted light as an amplitude-modulated waveform including an Nth-order harmonic component of a fundamental frequency and (ii) a second emitting portion of the plurality of emitting portions to emit the emitted light as an amplitude-modulated waveform including an Mth-order harmonic component of the fundamental frequency, wherein N and M are different positive integers,
• the second controller controls a particular receiving portion of the plurality of receiving portions corresponding to the first emitting portion to be sensible to the Nth-order harmonic component and the Mth-order harmonic component, and
• the multipath detector detects occurrence of the multipath error when the particular receiving portion senses both the Nth-order component and the Mth-order component.

A method for detecting a multipath error using a time-of-flight distance measuring technology, comprising:

• controlling, by a first controller, a light source to emit light, as emitted light, to illuminate a specified region;
• controlling, by a second controller, a light receiver to detect, as detected light, the emitted light reflected by an object in the specified region;
• calculating, by a calculator, a distance to the object based on the reflected light detected by the light receiver;
• and
• detecting, by a multipath detector, occurrence of a multipath error, wherein
• the specified region is divided into a plurality of sub-regions,
• the light source includes a plurality of emitting portions, each of the plurality of emitting portions illuminating a respective one of the plurality of sub-regions,
• the light receiver includes a plurality of receiving portions corresponding to respective ones of the plurality of emitting portions, each of the plurality of receiving portions being spaced away from each other to sense the reflected light reflected from the sub-region illuminated by the corresponding emitting portion,
• the first controller controls,
• at a first timing, (i) a first emitting portion of the plurality of emitting portions to emit the emitted light as an amplitude-modulated waveform including an Nth-order harmonic component of a fundamental frequency and (ii) a second emitting portion of the plurality of emitting portions to emit the emitted light as an amplitude-modulated waveform including an Mth-order harmonic component of the fundamental frequency, wherein N and M are different positive integers, and
• at a second timing, (i) the second emitting portion to emit the emitted light as an amplitude-modulated waveform including the Nth-order harmonic component of the fundamental frequency and (ii) the first emitting portion to emit the emitted light as an amplitude-modulated waveform including the Mth-order harmonic component of the fundamental frequency,
• the second controller controls,
• at the first timing, a first receiving portion of the plurality of receiving portions corresponding to the first emitting portion to be sensible to the Nth-order harmonic component and the Mth-order harmonic component, and
• at the second timing, a second receiving portion of the plurality of receiving portions corresponding to the second emitting portion to be sensible to the Nth-order harmonic component and the Mth-order harmonic component, and
• the multipath detector detects occurrence of the multipath error when (i) the first receiving portion senses, at the first timing, both the Nth-order component and the Mth-order component or (ii) the second receiving portion senses, at the second timing, both the Nth-order component and the Mth-order component.