Quasi-Kinematic Coupling for Optical Densitometer Precision

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Solution Overview

Problem

Densitometers face challenges in achieving high precision and repeatability due to kinematic constraints, particularly in multi-component devices where over-constraint can lead to reduced surface contact, affecting the accuracy of light measurement through transparent or semitransparent materials.

Innovation Solution

The implementation of a quasi-kinematic design in densitometers, utilizing a combination of kinematic couplings and quasi-kinematic constraints, such as line contacts and triangular geometry, to fix degrees of freedom and enhance precision, allowing for sub-micron tolerance and improved repeatability, while maintaining a weak over-constraint to reduce surface contact stress.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If kinematic constraints are used in multi-component densitometer devices, then assembly and alignment are simplified, but precision and repeatability deteriorate due to over-constraint reducing surface contact

Engineering Contradiction:

Improveassembly and alignmentVSAvoidprecision and repeatability

Core Design Contradiction:

Ease of manufactureVSMeasurement precision

Solution Approach 1:

The patent changes the constraint parameter from full kinematic constraint to quasi-kinematic constraint, allowing controlled degrees of freedom while maintaining alignment. This parameter change enables line contacts to provide sufficient constraint without over-constraint, thereby improving surface contact and measurement precision while keeping assembly simple.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies partial constraint rather than full constraint, using quasi-kinematic couplings that provide just enough restriction for alignment without excessive constraint. This partial action approach maintains measurement precision by avoiding over-constraint while still achieving the necessary assembly simplicity.

Inventive Principle:

Principle #16Partial or excessive action

2Measurement precision

If surface contact is reduced to improve repeatability, then kinematic constraint is weakened, but measurement stability deteriorates

Engineering Contradiction:

ImproverepeatabilityVSAvoidmeasurement stability

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent employs preliminary action through pre-configured quasi-kinematic couplings with line contacts that are designed to maintain stable surface contact before measurement begins. This preliminary arrangement ensures both repeatability and stability by establishing reliable contact conditions in advance without requiring full kinematic constraint.

Inventive Principle:

Principle #10Preliminary action

3Adaptability or versatility

If multi-component device is used to achieve functional complexity, then measurement capability is improved, but device complexity increases

Engineering Contradiction:

Improvemeasurement capabilityVSAvoiddevice complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent applies segmentation by dividing the densitometer into modular components (light source assembly, sample holder, detector assembly) connected through quasi-kinematic couplings. This segmentation enables functional complexity and measurement versatility while keeping individual components simple and the overall assembly manageable through standardized connection interfaces.

Inventive Principle:

Principle #1Segmentation

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 results in improved precision and repeatability in measuring optical density, enabling accurate determination of solids, non-volatile substances, and optical characteristics in fluids, such as ink, with enhanced stability and sealing capabilities, even when immersed in liquids.

Implementation Method 1

The electric current that is generated by the photovoltaic cell of the densitometer is typically directly proportional to the intensity of the incident light

Methodology Applied

Scientific EffectPhotovoltaic effect: Photovoltaic Effect

Implementation Method 2

measuring attenuation in the intensity of light which reaches the optical detector of the densitometer after passing through the measurable substance, the measurement being related to the absorption of light of the measurable substance

Methodology Applied

Scientific EffectLight transmission and absorption: Absorption (EM radiation)

Data Source

PatentUS8654336B2Optical measuring device

Publication Date: 2014.02.18 HEWLETT PACKARD INDIGO BV

AI summary

A device, system and method to measure an optical characteristic of a fluid, the device including a plurality of components consecutively arranged and coupled together via quasi kinematic or kinematic coupling. The consecutively arranged components define a void within the device. The void encloses a measuring set-up for measuring at least one optical characteristic of a fluid passing through a gap. The gap is located at an intersection between an optical path of the measuring set-up and a flow path of the fluid.