Scanning Unit Pore Filter for Dust and Condensation Control

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Solution Overview

Problem

Optical position measuring devices face interference from dust and moisture due to incomplete sealing and friction within the housing, which disrupts the light beam path, and hermetic seals can lead to condensation issues.

Innovation Solution

A dust-tight but gas- and vapor-permeable filter is used to prevent dust ingress while allowing moisture to escape, combined with a non-hermetic sealing approach that protects optical surfaces from dust and condensation by using a pore filter made from materials like ceramic or GORETEX, ensuring the light beam path remains undisturbed.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a hermetic seal is used to eliminate dust and moisture ingress, then protection of the scanning unit is improved, but condensation on optical surfaces occurs due to temperature changes

Engineering Contradiction:
Improvedust and moisture ingressVSAvoidtemperature changes causing condensation
Core Design Contradiction:
Object-affected harmful factorsVSTemperature

Solution Approach 1:

The patent employs a porous coating layer applied to the optical elements within the scanning unit. This porous layer allows water vapor to pass through while blocking liquid water and dust particles, thereby preventing condensation on optical surfaces during temperature changes while maintaining protection against dust and moisture ingress.

Inventive Principle:
Principle #31Porous materials

2Temperature

If the housing is opened with a filter to allow oil escape, then moisture venting is improved, but dust can still penetrate and disrupt the light beam path

Engineering Contradiction:
Improvemoisture ventingVSAvoiddust penetration
Core Design Contradiction:
TemperatureVSObject-affected harmful factors

Solution Approach 1:

The patent applies a porous coating layer to optical elements that functions as a selective barrier. The pore structure allows gas molecules (water vapor, oil vapors) to diffuse through while the pore dimensions block larger dust particles and liquid droplets, thus enabling moisture venting while preventing dust penetration.

Inventive Principle:
Principle #31Porous materials

3Measurement precision

If guide elements are used to guide the scanning unit, then positioning accuracy is improved, but friction generates dust that disrupts the light beam path

Engineering Contradiction:
Improvepositioning accuracyVSAvoidfriction dust
Core Design Contradiction:
Measurement precisionVSObject-generated harmful factors

Solution Approach 1:

The patent introduces a porous coating layer as an intermediary protective barrier on optical elements. This layer intercepts friction dust generated by guide elements before the dust can contaminate the light beam path, allowing the guide elements to continue providing positioning accuracy without generating harmful dust interference.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 ensures reliable operation of the position measuring device under unfavorable conditions by preventing dust interference and allowing moisture to escape, thus maintaining an undisturbed light beam path and preventing condensation on optical surfaces.

Implementation Method 1

an encasement for the scanning unit with at least one optical element, which has a pore filter applied to it, the pore filter having a pore structure, by which dust is prevented from penetrating into the encasement interior, through which, however, gas molecules and water vapor can pass

Methodology Applied
Scientific EffectPhysical filtration through porous material: Filter (physical)

Implementation Method 2

the pore filter having a pore structure, by which dust is prevented from penetrating into the encasement interior, through which, however, gas molecules and water vapor can pass

Methodology Applied
Scientific EffectPermeation through porous structure: Permeation

Implementation Method 3

allowing moisture to escape, thus maintaining an undisturbed light beam path and preventing condensation on optical surfaces

Methodology Applied
Scientific EffectVapor transmission through porous material: Porosity

Data Source

PatentEP1762827B1Scanning unit of an optical position measuring device and optical position measuring device
Publication Date: 2008.09.03 DR JOHANNES HEIDENHAIN GMBH
  • EP1762827B1 patent drawingFigure 1
  • EP1762827B1 patent drawingFigure 2~3
  • EP1762827B1 patent drawingFigure 4

AI summary

Scanning unit (2) of optical position measuring device has the internal space and the external space which are connected by a filter (13). Scanning unit of optical position measuring device are dust proof, but gas and steam are permeable. Scanning unit has the filter which is impermeable for water in liquid form. An independent claim is also included for the position measuring device.