# US 8,786,837 B2 · Distance measuring apparatus

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- Number: US 8,786,837 B2
- Document ID: US8786837B2
- Status: Granted
- Kind: B2
- Application number: 13/542,224
- Filed: 2012-07-05
- Published: 2013-01-10
- Granted: 2014-07-22
- Earliest claimed: 2011-07-08
- Assignees: Nikon Vision Co., Ltd.
- Applicants: Hitoshi Ohmuro
- Inventors: Hitoshi Ohmuro
- Web page: https://patentgrep.com/patent/US8786837B2

## CPC

- G01S 17/10: using transmission of interrupted, pulse-modulated waves (determination of distance by phase measurements G01S17/32)
- G01S 7/497: Means for monitoring or calibrating
- G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES

## Abstract

The present application provides a distance measuring apparatus that can measure a distance with accuracy even when a light receiving level of a reflected light becomes saturated. A light emitting section of the distance measuring apparatus emits a measuring light toward an object to be measured. A light receiving section receives the reflected light being reflected from the object to be measured. A distance calculating section obtains a distance to the object to be measured based on an elapsed time which is from a point the measuring light is emitted until a point a light receiving level of the reflected light indicates a peak thereof. A distance correcting section corrects a value of the distance to the object to be measured depending on a length of saturation time of the light receiving level when the light receiving level becomes saturated and the peak is impossible to identify.

## Claims

### Claim 1

A distance measuring apparatus comprising:
a light emitting section emitting a measuring light toward an object to be measured;
a light receiving section receiving a reflected light being reflected from the object to be measured;
a distance calculating section obtaining a distance to the object to be measured based on an elapsed time which is from a point the measuring light is emitted until a point a light receiving level of the reflected light indicates a peak thereof; and
a distance correcting section correcting a value of the distance to the object to be measured depending on a length of saturation time of the light receiving level when the light receiving level becomes saturated and the peak is impossible to identify, wherein:
the light emitting section emits the measuring light a plurality of times,
the distance calculating section further includes a counting section counting each point where the light receiving section measured a light received amount exceeding a threshold value when the measuring light is emitted the plurality of times and obtaining the light receiving level at each point by accumulating a frequency being counted,
the distance calculating section obtains the distance to the object to be measured based on an elapsed time at a point where an accumulated number of the frequency indicates a peak thereof, and
the distance correcting section corrects, when the accumulated number of the frequency becomes a saturated state, the value of the distance to the object to be measured depending on a length of time in the saturated state.

### Claim 2 (depends on 1)

The distance measuring apparatus according to claim 1, wherein
the distance correcting section increases a correction amount for correcting the value of the distance as the length of saturation time of the light receiving level becomes longer.