Confocal Displacement Measurement with Dynamic Range Reset

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Solution Overview

Problem

Conventional displacement measuring devices face challenges in accurately measuring distances to measurement target surfaces, particularly when reflected light is unstable or when the measurement target surface deviates from the measurement range, leading to incorrect processing of distances.

Innovation Solution

A displacement measuring device using a white confocal method with a sensor controller that adjusts setting ranges based on detected peak wavelengths, ensuring accurate measurement by processing only distances within predefined ranges and adjusting these ranges dynamically to prevent error processing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the measurement range is set wide to cover all possible target surfaces, then the device can detect more surfaces, but it processes incorrect distance data when surfaces are outside the intended measurement range

Engineering Contradiction:
Improveability to detect multiple surfacesVSAvoidaccuracy of distance measurement
Core Design Contradiction:
Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The measurement range is dynamically adjusted based on the detected peak wavelength. When a peak wavelength is detected within the current measurement range, the system narrows the range to this detected position. This dynamic adjustment allows the system to adapt to different target surfaces while maintaining measurement precision by ensuring only surfaces within the adjusted range are processed.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system applies different processing rules to different wavelength ranges. By identifying the peak wavelength and setting the measurement range specifically around this peak, the system ensures that only locally relevant distance data (within the peak wavelength range) is processed, while excluding data from surfaces outside this range even if they are detected.

Inventive Principle:
Principle #3Local quality

2Measurement precision

If the measurement range is set narrow to ensure precise measurement of specific surfaces, then measurement accuracy is improved, but the device cannot detect surfaces that deviate from the preset range

Engineering Contradiction:
Improveaccuracy of distance measurementVSAvoidability to detect multiple surfaces
Core Design Contradiction:
Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The system performs a preliminary detection of the peak wavelength before finalizing the measurement range. This preliminary action allows the system to identify which surfaces are present and then adjust the measurement range accordingly, ensuring both precision for detected surfaces and adaptability to different configurations.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system uses feedback from the detected peak wavelength to continuously adjust the measurement range. When a peak is detected, the range is updated to center around this peak, creating a feedback loop that maintains both precision and adaptability as measurement conditions change.

Inventive Principle:
Principle #23Feedback

3Quantity of substance

If the device processes all detected wavelengths to maximize data collection, then more surfaces are measured, but error processing increases when reflected light is unstable

Engineering Contradiction:
Improveamount of measurement dataVSAvoidconsistency of measurement results
Core Design Contradiction:
Quantity of substanceVSReliability

Solution Approach 1:

The system extracts only the relevant measurement data by identifying the peak wavelength and processing only distances corresponding to this peak. By taking out and focusing on the most significant signal (the peak wavelength), the system maximizes data quality while minimizing errors from unstable reflected light from other surfaces.

Inventive Principle:
Principle #2Taking out (Extraction)

4Device complexity

If the device uses a fixed measurement range to simplify processing, then device complexity is reduced, but measurement accuracy deteriorates when target surfaces deviate from the fixed range

Engineering Contradiction:
Improvesimplicity of processing logicVSAvoidaccuracy of distance measurement
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The measurement range transitions from a fixed preset value to a dynamic value that automatically adjusts based on the detected peak wavelength. This dynamic adjustment maintains simple processing logic while significantly improving measurement accuracy for surfaces at varying distances.

Inventive Principle:
Principle #15Dynamics

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

The solution enables accurate measurement of distances to each measurement target surface by dynamically adjusting setting ranges, reducing error processing and improving data accuracy even when reflected light is unstable or the target surface deviates, thus ensuring precise displacement measurement.

Implementation Method 1

an irradiation part which irradiates light to a measurement target having a plurality of layers which can allow light to pass through so that the light is focused at different positions on an optical axis for each wavelength

Methodology Applied
Scientific EffectChromatic aberration:

Implementation Method 2

a head sensor which receives light of the irradiated light reflected by a measurement target surface of each of the plurality of layers

Methodology Applied
Scientific EffectLight refraction and focusing: Lens

Implementation Method 3

a light receiving part which receives light of each wavelength focused on and reflected by a measurement target surface of each of the plurality of layers and also detects each wavelength from the received light

Methodology Applied
Scientific EffectLight reflection: Reflection

Data Source

PatentEP3460387B1Displacement measuring device, measuring system and displacement measuring method
Publication Date: 2020.05.13 OMRON CORP
  • EP3460387B1 patent drawingFigure 1
  • EP3460387B1 patent drawingFigure 2~3
  • EP3460387B1 patent drawingFigure 4~5

AI summary

A displacement measuring device capable of accurately measuring a distance (L1(i), L2(i), L3(i), L4(i)) to a measurement target surface is provided. The displacement measuring device includes a light projecting part generating light, a sensor head irradiating a measurement target with the light and receiving light of the irradiated light reflected by a measurement target surface of the measurement target, and a control part calculating a value indicating a distance (L1(i), L2(i), L3(i), L4(i)) to the measurement target surface on the basis of the light received by the sensor head. The control part processes the calculated value as the value indicating the distance (L1(i), L2(i), L3(i), L4(i)) to the measurement target surface on condition that the calculated value is included in a preset numerical range (Rl(i), R2(i), R3(i), R4(i)) and resets the preset numerical range (R1(i), R2(i), R3(i), R4(i)) on the basis of the calculated value.