Fluid Ejection Die Strain Gauge Sensor Impact Detection

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Solution Overview

Problem

Inkjet printing systems face challenges in detecting and reacting to impacts between the printhead and medium, leading to potential damage and waste due to undetected printhead impacts, which can result in smeared prints or complete halt of the medium, causing large customer losses.

Innovation Solution

Integration of strain gauge sensors within the fluid ejection die to continuously monitor for impacts, providing a fault signal to stop or modify the operation of the system, and alerting users when an impact is detected, allowing for immediate action to prevent further damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If strain gauge sensors are integrated within the fluid ejection die, then impact detection capability is improved, but device complexity increases

Engineering Contradiction:
Improveimpact detection capabilityVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The strain gauge sensor is integrated directly within the fluid ejection die, merging the sensing function with the existing printhead structure. This consolidation enables impact detection without requiring a separate, external monitoring system, thereby improving reliability while limiting the increase in overall device complexity.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The strain gauge sensor acts as an intermediary element between the mechanical impact event and the electronic control system. It converts mechanical stress from impacts into electrical signals that can be processed by the controller, enabling indirect but effective impact detection and system response.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Loss of time

If continuous monitoring of strain gauge sensors is implemented, then impact detection timing is improved, but energy consumption increases

Engineering Contradiction:
Improveimpact detection timingVSAvoidenergy consumption
Core Design Contradiction:
Loss of timeVSUse of energy by moving object

Solution Approach 1:

The strain gauge sensor provides continuous monitoring of mechanical stress in real-time during printhead operation. This continuous action enables immediate detection of impacts without interruption or delay, allowing the system to respond instantly to impact events and prevent damage.

Inventive Principle:
Principle #20Continuity of useful action

Solution Approach 2:

The strain gauge sensor replaces complex mechanical impact detection mechanisms with a simpler electrical sensing system. By substituting mechanical measurement methods with electrical strain gauging, the system achieves continuous monitoring with lower energy consumption compared to traditional mechanical impact sensors.

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

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 early detection of printhead impacts, preventing damage and reducing waste by allowing for immediate system intervention, thereby maintaining print quality and extending printhead lifespan.

Implementation Method 1

at least one strain gauge sensor integrated within a fluid ejection die of the fluid ejection system

Methodology Applied
Scientific EffectStrain gauge effect: Piezoresistive Effect

Data Source

PatentEP3558687B1Fluid ejection dies including strain gauge sensors
Publication Date: 2022.08.03 HEWLETT PACKARD DEVELOPMENT COMPANY LP
  • EP3558687B1 patent drawingFigure 1A~1B
  • EP3558687B1 patent drawingFigure 1C
  • EP3558687B1 patent drawingFigure 2A~2B

AI summary

A fluid ejection die includes a plurality of actuation devices to eject fluid drops, at least one strain gauge sensor to sense strain, and a comparator. The comparator is to provide a fault signal in response to the sensed strain exceeding an impact threshold.