Ink Viscosity Estimation via Transit Time Measurement

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Solution Overview

Problem

Existing ink-jet recording apparatuses cannot accurately estimate the viscosity of ink in an ink container, especially when the ink has not been mounted or has been unused, and rely on indirect methods that do not account for physical measurements.

Innovation Solution

A liquid consuming apparatus that measures the transit time of ink flowing from a first chamber to a second chamber, where the flow rate varies with viscosity, allowing for direct estimation of the ink's viscosity by measuring the movement of a movable member as the ink surface rises in the second chamber.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If indirect methods (elapsed time and ink amount) are used to estimate viscosity, then the device complexity is reduced, but the measurement precision deteriorates

Engineering Contradiction:
Improvedevice complexityVSAvoidmeasurement precision
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent replaces indirect estimation methods with direct physical measurement using a pressure sensor to measure the pressure difference across a known flow resistance. This substitution of measurement methodology achieves precise viscosity measurement without requiring complex mechanical viscometer structures, thus improving measurement precision while maintaining reasonable device complexity

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces a flow resistance element as an intermediary component between the ink chamber and the pressure sensor. This intermediary allows the system to convert the viscous flow characteristics into a measurable pressure difference, enabling accurate viscosity estimation through a simple pressure measurement rather than direct complex mechanical measurement

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If direct physical measurement of ink flow is implemented, then the measurement precision improves, but the device complexity increases

Engineering Contradiction:
Improvemeasurement precisionVSAvoiddevice complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces complex mechanical viscometer structures with a simple pressure sensor-based measurement system. By measuring pressure difference across a known flow resistance, the system achieves direct physical measurement of viscosity without requiring moving parts or complex mechanical mechanisms

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent utilizes the hydraulic properties of ink flow through a restricted passage to create a measurable pressure difference. The flow resistance element creates a hydraulic relationship where pressure difference is directly related to flow rate and viscosity, enabling measurement through pressure sensing rather than complex mechanical means

Inventive Principle:
Principle #29Pneumatics and hydraulics

3Reliability

If viscosity measurement capability is added to all ink cartridges, then the reliability improves, but the manufacturing precision requirements increase

Engineering Contradiction:
ImprovereliabilityVSAvoidmanufacturing precision
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The patent separates the viscosity measurement function from the ink storage function by implementing it only in refillable ink cartridges that have a removable seal. This segmentation allows viscosity measurement to be added selectively to cartridges where it provides value, without requiring all ink cartridges to meet higher manufacturing precision standards

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent performs viscosity measurement at the time of cartridge installation or refilling, before the ink is used. This preliminary measurement ensures reliable viscosity data is available for optimal printing performance without requiring continuous monitoring throughout the ink's usage life

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

Enables accurate estimation of ink viscosity, preventing issues related to unusual viscosity that could affect printing performance and allowing for timely replacement of ink cartridges, even when they have been unused for a long time.

Implementation Method 1

the liquid moves from the first liquid chamber to the second liquid chamber through the communication path

Methodology Applied
Scientific EffectFluid flow:

Implementation Method 2

The flow rate of the liquid moving from the first liquid chamber to the second liquid chamber varies depending on the viscosity of liquid in the liquid chamber

Methodology Applied
Scientific EffectViscosity:

Implementation Method 3

the velocity of the first movable member which moves as the liquid surface in the second liquid chamber moves up varies depending on the flow rate of the liquid

Methodology Applied
Scientific EffectFluid flow rate:

Data Source

PatentEP2990208B1Liquid consuming apparatus
Publication Date: 2018.10.03 BROTHER KOGYO KK
  • EP2990208B1 patent drawingFigure 1
  • EP2990208B1 patent drawingFigure 2
  • EP2990208B1 patent drawingFigure 3A~3B

AI summary

A liquid consuming apparatus includes a liquid cartridge including a first liquid chamber, a second liquid chamber, and a movable member positioned in the second liquid chamber and including a detection portion and a float. The apparatus also includes a mount detector configured to selectively output a first signal when the liquid cartridge is not in a mount detection position and a second signal when the liquid cartridge in in the mount detection position, a detector configured to selectively output a third signal when the detection portion is not in a detection position and a fourth signal when the detection portion is in the detection position, and a controller configured to measure a transit time from when the signal output from the mount detector changes from the first signal to the second signal to when the signal output from the detector changes from one of the third signal and the fourth signal to the other of the third signal and the fourth signal, and determine whether the transit time is within a threshold range.