Optical Distance Measurement with Range-Adaptive Reference Light

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Solution Overview

Problem

The Time of Flight (ToF) method in optical distance measurement devices faces challenges in achieving desired reception sensitivity due to varying measurement conditions, particularly when measuring objects at different distances, leading to issues with power consumption and sensitivity.

Innovation Solution

The optical distance measurement device employs intensity modulation of reference light based on the distance measurement range, generating reference light pulses to improve reception sensitivity without increasing power consumption by using a light amplifier.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the ToF method is used to measure distance by time period from transmission to detection of reflected light pulse, then distance measurement capability is achieved, but reception sensitivity cannot be optimized for different measurement conditions

Engineering Contradiction:
Improvereception sensitivityVSAvoidadaptability to different measurement conditions
Core Design Contradiction:
Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The reference light intensity is dynamically adjusted based on the distance measurement range. The modulation unit changes the intensity of reference light according to the selected measurement range, allowing the system to adapt to different measurement conditions and optimize reception sensitivity for each scenario.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system changes the intensity parameter of reference light based on the distance measurement range. By modulating the reference light intensity to match the measurement range, the system achieves optimal reception sensitivity for near, middle, and far distance measurements without requiring multiple fixed-intensity light sources.

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If reference light intensity is increased to improve reception sensitivity, then measurement sensitivity improves, but power consumption increases

Engineering Contradiction:
Improvereception sensitivityVSAvoidpower consumption
Core Design Contradiction:
Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The reference light intensity is dynamically adjusted based on the distance measurement range. The modulation unit changes the intensity of reference light according to the selected measurement range, allowing the system to adapt to different measurement conditions and optimize reception sensitivity for each scenario.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system changes the intensity parameter of reference light based on the distance measurement range. By modulating the reference light intensity to match the measurement range, the system achieves optimal reception sensitivity for near, middle, and far distance measurements without requiring multiple fixed-intensity light sources.

Inventive Principle:
Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach enhances reception sensitivity across varying distances while maintaining consistent average power, allowing for accurate distance measurements over a wide range without excessive power usage.

Implementation Method 1

generating reference light acquired by performing intensity modulation on a light source according to a distance measurement range

Methodology Applied
Scientific EffectIntensity modulation:

Implementation Method 2

generating a reception signal by causing the received reflected light and the generated reference light to interfere with each other

Methodology Applied
Scientific EffectLight interference: Interference

Data Source

PatentEP4212907B1Optical distance measurement device and optical distance measurement method
Publication Date: 2025.12.03 NEC CORP
  • EP4212907B1 patent drawingFigure 1
  • EP4212907B1 patent drawingFigure 2
  • EP4212907B1 patent drawingFigure 3

AI summary

An optical distance measurement device (10) includes a light transmission unit (11) that transmits distance measurement light to a measurement object, a light reception unit (12) that receives reflected light being reflected from the measurement object by the transmitted distance measurement light, a modulation unit (13) that generates reference light acquired by performing intensity modulation on a light source according to a distance measurement range, a detection unit (14) that generates a reception signal by causing the received reflected light and the generated reference light to interfere with each other, and a distance calculation unit (15) that calculates a distance to the measurement object, based on the transmitted distance measurement light and the generated reception signal.