Light wave distance meter

Patent metadata

Field	Value
Publication number	US-11353586-B2
Application number	US-202016829471-A
Country	US
Kind code	B2
Filing date	Mar 25, 2020
Priority date	Mar 26, 2019
Publication date	Jun 7, 2022
Grant date	Jun 7, 2022

Abstract

A light wave distance meter according to the present invention includes: a light-emitting element that emits a distance measurement light; a light-receiving element that outputs a light-receiving signal; a frequency conversion unit that includes a bandpass filter; an arithmetic control unit that computes a distance value to a measurement object; a signal generator that generates a signal having a predetermined frequency; a waveform conversion unit that generates a waveform conversion signal; pulse generators that generate pulse signals by pulsating the signal having a predetermined frequency so as to have a waveform profile of a signal constituted of desired frequency components on the basis of the signal output from the signal generator and the waveform conversion signal output from the waveform conversion unit; and a drive unit that emits the distance measurement light based on the pulse signals.

First claim

What is claimed is:

1. A light wave distance meter that irradiates a measurement object with a distance measurement light, and measures a distance to the measurement object based on a reflected distance measurement light that is the distance measurement light reflected by the measurement object, comprising:
a light-emitting element that emits the distance measurement light;
a light-receiving element that receives the reflected distance measurement light and outputs a light-receiving signal in accordance with the reflected distance measurement light;
a frequency conversion unit that includes a bandpass filter that allows a specific frequency band to pass, out of the light-receiving signal output from the light-receiving element and includes a timing signal generator that generates a pulse signal of a rectangular wave;
an arithmetic control unit that executes arithmetic processing to determine a distance value to the measurement object based on the signal output from the frequency conversion unit;
a signal generator that generates a signal having a predetermined frequency;
a waveform conversion unit that generates a waveform conversion signal by converting a waveform profile of the rectangular wave of the pulse signal output from the timing signal generator, the waveform conversion signal constituted of desired frequency components used for the measurement of the distance;
a pulse generator that generates a pulse signal by pulsating the signal having the frequency output from the signal generator, so as to have a waveform profile of a signal constituted of desired frequency components used for the measurement of the distance, based on the signal having the frequency and the waveform conversion signal output from the waveform conversion unit; and
a drive unit that drives the light-emitting element and causes the light-emitting element to emit the distance measurement light based on the pulse signal generated by the pulse generator.

2. The light wave distance meter according to claim 1 , wherein
the signal generator generates a first modulation signal modulated by a first frequency, and a second modulation signal modulated by a second frequency which is close to the first frequency,
the pulse generator generates a first pulse modulation signal generated by pulsating the first modulation signal so as to have a waveform profile of a signal constituted of desired frequency components used for the measurement of the distance based on the first modulation signal output from the signal generator and the waveform conversion signal output from the waveform conversion unit, and a second pulse modulation signal generated by pulsating the second modulation signal so as to have a waveform profile of a signal constituted of desired frequency components used for the measurement of the distance based on the second modulation signal output from the signal generator and the waveform conversion signal output from the waveform conversion unit,
the drive unit drives the light-emitting element based on the first pulse modulation signal and the second pulse modulation signal, and switches and emits a first distance measurement light modulated by the first frequency and a second distance measurement light modulated by the second frequency,
the light-receiving element receives a first reflected distance measurement light corresponding to the first distance measurement light reflected by the measurement object, and a second reflected distance measurement light corresponding to the second distance measurement light reflected by the measurement object,
the frequency conversion unit generates a first difference frequency signal by performing frequency conversion on the first reflected distance measurement light received by the light-receiving element, and generates a second difference frequency signal that has a phase difference in accordance with the distance to the measurement object with respect to the first difference frequency signal, by performing frequency conversion on the second reflected distance measurement light received by the light-receiving element, and
the arithmetic control unit executes arithmetic processing to determine a distance value to the measurement object based on the first difference frequency signal and the second difference frequency signal.

3. The light wave distance meter according to claim 1 , wherein the waveform profile of the waveform conversion signal is a waveform profile expressed by a parabolic function.

4. The light wave distance meter according to claim 2 , wherein the waveform profile of the waveform conversion signal is a waveform profile expressed by a parabolic function.

5. The light wave distance meter according to claim 1 , wherein the waveform profile of the waveform conversion signal is a waveform profile of a triangular wave.

6. The light wave distance meter according to claim 2 , wherein the waveform profile of the waveform conversion signal is a waveform profile of a triangular wave.

7. The light wave distance meter according to claim 1 , wherein the waveform profile of the waveform conversion signal is a waveform profile of a sawtooth wave.

8. The light wave distance meter according to claim 2 , wherein the waveform profile of the waveform conversion signal is a waveform profile of a sawtooth wave.

9. The light wave distance meter according to claim 1 , wherein the waveform profile of the waveform conversion signal is a waveform profile expressed by a Gaussian function.

10. The light wave distance meter according to claim 2 , wherein the waveform profile of the waveform conversion signal is a waveform profile expressed by a Gaussian function.

Assignees

• Topcon Corp

Inventors

• Shoji Naoki

Classifications

• G01S7/32

  Shaping echo pulse signals; Deriving non-pulse signals from echo pulse signals · CPC title

• G01S17/34 Primary

  using transmission of continuous, frequency-modulated waves while heterodyning the received signal, or a signal derived therefrom, with a locally-generated signal related to the contemporaneously transmitted signal · CPC title

• G01S7/493

  Extracting wanted echo signals · CPC title

• G01S7/28

  Details of pulse systems · CPC title

• G01S7/483

  Details of pulse systems · CPC title