Fluid Ejection Sensor Unit for Impedance Detection

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Solution Overview

Problem

Fluid ejection devices, such as inkjet printheads, face challenges in accurately detecting fluid impedance without wasting fluid and maintaining throughput, particularly in determining fluid characteristics like ion concentration and compatibility.

Innovation Solution

Incorporating a sensor unit with a sensor plate, capable of detecting impedance changes at varying temperatures, and using multi-frequency excitation signals for electrochemical impedance spectroscopy to identify fluid characteristics, allowing for precise impedance measurement and fluid identification.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional fluid detection methods are used, then fluid characteristics can be detected, but fluid waste increases and throughput decreases

Engineering Contradiction:

Improvefluid impedance detection accuracyVSAvoidfluid waste

Core Design Contradiction:

Measurement precisionVSLoss of substance

Solution Approach 1:

The patent introduces a sensor unit as an intermediary component that can detect fluid impedance through the substrate without requiring direct fluid contact or fluid consumption. The sensor unit includes sensing elements that measure electrical impedance changes caused by fluid presence and characteristics, enabling detection without wasting fluid.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces traditional mechanical or consumable-based detection methods with an electrical field-based sensing system. By using electrical impedance measurement through the substrate, the system eliminates the need for fluid consumption while achieving accurate detection of fluid characteristics.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If traditional fluid detection methods are used, then fluid characteristics can be detected, but device throughput decreases

Engineering Contradiction:

Improvefluid impedance detection accuracyVSAvoiddevice throughput

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

The sensor unit enables continuous monitoring of fluid characteristics without interrupting the fluid ejection process. The sensing operates continuously through the substrate while fluid is being ejected, maintaining uninterrupted productivity while providing ongoing detection capability.

Inventive Principle:

Principle #20Continuity of useful action

Solution Approach 2:

The substrate acts as an intermediary that allows electrical signals to pass through to the fluid and back, enabling detection without requiring separate detection chambers or interrupting the main ejection pathway. This maintains continuous operation and high throughput.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Measurement precision

If multi-frequency excitation signals are used for electrochemical impedance spectroscopy, then fluid characteristic identification improves, but device complexity increases

Engineering Contradiction:

Improvefluid characteristic identification accuracyVSAvoidsensor unit complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The sensor unit is designed to perform multiple functions: it can detect fluid presence, measure fluid impedance, identify fluid characteristics through multi-frequency analysis, and potentially monitor multiple fluid properties simultaneously. This multi-functionality is achieved through a relatively simple integrated structure that reduces overall system complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 detection of fluid impedance and characteristics, improving fluid ejection device stability and efficiency by minimizing fluid waste and enhancing throughput, while ensuring compatibility and quality of the fluid used.

Implementation Method 1

capable of detecting impedance changes at varying temperatures

Methodology Applied

Scientific EffectImpedance detection: Electrical Impedance Tomography

Implementation Method 2

detecting impedance changes at varying temperatures

Methodology Applied

Scientific EffectTemperature-dependent impedance variation:

Implementation Method 3

using multi-frequency excitation signals for electrochemical impedance spectroscopy to identify fluid characteristics

Methodology Applied

Scientific EffectElectrochemical impedance spectroscopy:

Implementation Method 4

a temperature adjustment module to establish at least one temperature of the fluid of the fluid ejection device

Methodology Applied

Scientific EffectTemperature control:

Data Source

PatentEP2741918B1Fluid ejection devices and methods thereof

Publication Date: 2020.01.01 HEWLETT PACKARD DEVELOPMENT COMPANY LP

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AI summary

Fluid ejection devices and methods thereof are disclosed in the present disclosure. A method includes establishing fluid communication between an ejection chamber and a fluid supply chamber of the fluid ejection device such that the ejection chamber includes a nozzle and an ejection member to selectively eject fluid through the nozzle. The method also includes detecting at least one impedance in the fluid by a sensor unit having a sensor plate.