Touch Probe Elastic Membrane Radial Measurement Accuracy

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Solution Overview

Problem

Existing touch sensors with three-point bearing mechanisms exhibit unequal movement characteristics, leading to measurement inaccuracies in radial directions due to their distinctive lever characteristics.

Innovation Solution

A touch probe design featuring an elastic membrane connecting the stylus holder to the stylus bearing, ensuring uniform radial measurement sensitivity and damping external vibrations, with a rotationally symmetrical membrane that deforms and returns to its initial state, improving measurement accuracy and sensitivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a three-point bearing mechanism is used to support the stylus holder, then the stylus holder can be movably mounted on the housing, but the movement characteristic becomes unequal radially about the longitudinal axis, leading to measurement inaccuracy

Engineering Contradiction:
Improvemovable mounting of stylus holderVSAvoidradial measurement accuracy
Core Design Contradiction:
Ease of operationVSMeasurement precision

Solution Approach 1:

The patent extracts the problematic three-point bearing mechanism and replaces it with a membrane-based support system. The membrane is connected to the housing at multiple points (typically three or more) but distributes the support forces uniformly across the entire membrane surface, eliminating the lever characteristic and unequal movement characteristics of the three-point bearing while maintaining the movable mounting function.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the physical state and mechanical properties of the support system by using an elastic membrane with specific material properties (elastic modulus, thickness, density) that provide uniform radial compliance. The membrane's elastic deformation characteristics ensure equal movement characteristics in all radial directions, improving measurement accuracy while maintaining mobility.

Inventive Principle:
Principle #35Parameter changes

2Object-affected harmful factors

If the membrane thickness is increased to dampen external vibrations, then vibration damping improves, but the membrane becomes less flexible and may reduce measurement sensitivity

Engineering Contradiction:
Improvevibration dampingVSAvoidmeasurement sensitivity
Core Design Contradiction:
Object-affected harmful factorsVSMeasurement precision

Solution Approach 1:

The patent optimizes the membrane thickness parameter within a specific range (typically 0.1-5 mm) to achieve the desired balance between vibration damping and measurement sensitivity. The thickness is selected based on the frequency range of vibrations to be damped and the required measurement sensitivity, creating an optimal compromise that satisfies both requirements.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent may employ composite membrane structures combining materials with different damping and flexibility characteristics. By selecting appropriate material compositions and layer structures, the membrane achieves enhanced vibration damping properties while maintaining the flexibility required for high measurement sensitivity.

Inventive Principle:
Principle #40Composite materials

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 touch probe achieves improved measurement characteristics and sensitivity by providing uniform radial probing sensitivity and dampening external vibrations, enhancing the accuracy of radial measurements in the X and Y directions.

Implementation Method 1

The stylus holder has a membrane, the membrane being formed between the stylus holder and the stylus bearing of the stylus holder, the elastic membrane connecting the stylus holder to the stylus bearing

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

The membrane advantageously dampens a movement or force of the stylus holder which is caused by external vibrations

Methodology Applied
Scientific EffectVibration damping: Damping

Data Source

PatentEP3516323B1Touch probe
Publication Date: 2021.07.28 M&H INPROCESS MESSTECHNIK GMBH
  • EP3516323B1 patent drawingFigure 1
  • EP3516323B1 patent drawingFigure 2

AI summary

The invention relates to a touch probe having a housing and a stylus holder, wherein the stylus holder comprises a stylus bearing and a stylus receptacle, the stylus receptacle being provided to receive a stylus, wherein the stylus holder is movably supported on the housing by means of the stylus bearing. The touch probe is characterized in that the stylus holder has a membrane, said membrane being formed between the stylus receptacle and the stylus bearing of the stylus holder.