Liquid Level Detection Sensor Assembly Robustness

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Solution Overview

Problem

Existing liquid level detection sensors in specimen testing apparatuses are prone to assembly errors and are easily affected by bubbles or menisci, leading to inaccurate liquid level detection and reduced productivity.

Innovation Solution

The design integrates light emitters and detectors on the same board with light path members that are formed integrally with the flow path, using reflective surfaces and a condensing lens to improve robustness against assembly errors and minimize the impact of bubbles or menisci, allowing for accurate liquid level detection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the light emitting element and the light detecting element are placed across the tube to achieve high detection sensitivity, then the detection sensitivity of the liquid level is improved, but the assembly errors among the tube, the light emitting element, the slit, and the light detecting element largely affect the sensitivity, and all components must be accurately positioned making assembly difficult and productivity lowered

Engineering Contradiction:
Improvedetection sensitivityVSAvoidassembly difficulty
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

The light emitting element and light detecting element are integrated onto a single board structure, which is then attached to the tube. This merging of components eliminates the need for separate positioning of multiple elements across the tube, thereby maintaining high detection sensitivity while significantly simplifying the assembly process and improving productivity.

Inventive Principle:
Principle #5Merging (Combining)

2Measurement precision

If the detection sensitivity is high, then the liquid level detection is more accurate, but the detection is easily affected by a bubble or meniscus in the tube, causing erroneous detection

Engineering Contradiction:
Improvedetection accuracyVSAvoidsensitivity to bubbles and menisci
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

A light path member with a light incident surface and a light outgoing surface is introduced as an intermediary component. This member is disposed inside the tube and directs light along the tube's inner surface, allowing the detection to occur at a position away from direct interaction with bubbles or menisci, thereby reducing their harmful effects while maintaining detection accuracy.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Measurement precision

If all components are accurately positioned to prevent detection errors, then the accuracy of detection is improved, but the assembly work is difficult and productivity is lowered

Engineering Contradiction:
Improvedetection accuracyVSAvoidmass production efficiency
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The light emitting element and light detecting element are merged onto a single board, which is then attached to the tube as an integrated unit. This merging reduces the number of separate positioning operations required, thereby maintaining detection accuracy while significantly improving assembly efficiency and productivity for mass production.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The light emitting element and light detecting element are pre-positioned and fixed onto the board before the board is attached to the tube. This preliminary action ensures accurate relative positioning of the optical components while simplifying the final assembly step, thereby improving both detection accuracy and production efficiency.

Inventive Principle:
Principle #10Preliminary action

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 configuration enhances the robustness against assembly errors, improves detection accuracy, and increases productivity by reducing the influence of bubbles or menisci, facilitating easier assembly and mass production.

Implementation Method 1

a light emitter 170-1A that emits a light beam 151

Methodology Applied
Scientific EffectLight emission: Light Emitting Diode

Implementation Method 2

a light detector 170-1B that receives the light beam 151

Methodology Applied
Scientific EffectLight detection: Photoelectric Effect

Implementation Method 3

a first surface 180-1A that reflects the light beam 151, and a second surface 180-1B that reflects the light beam 151

Methodology Applied
Scientific EffectLight reflection: Reflection

Implementation Method 4

a condensing lens 190 that condenses the light beam 151 onto the light detector 170-1B

Methodology Applied
Scientific EffectLight condensation: Lens

Data Source

PatentEP3492882B1Liquid level detection sensor and specimen testing apparatus
Publication Date: 2023.03.08 NIHON KOHDEN CORP
  • EP3492882B1 patent drawingFigure 1~2
  • EP3492882B1 patent drawingFigure 3
  • EP3492882B1 patent drawingFigure 4A~4B

AI summary

A specimen testing apparatus includes a light emitter that emits a light beam, a first surface that reflects the light beam emitted from the light emitter, a flow path that allows a liquid to pass through a light path of the light beam that is reflected by the first surface, a second surface that reflects the light beam transmitted through the flow path, and a light detector that receives the light beam reflected by the second surface. In the apparatus, the light emitter and the light detector are disposed on a board, the first surface, the flow path, and the second surface are formed integrally in a light path member, and the board is attached to a housing in which the light path member is formed.