Impedance-Based Servicing for Fluid Ejection Reliability
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Solution Overview
Problem
Printing devices face challenges in detecting and addressing defects in fluid ejection systems, such as particle blockages, pigment separation, and bubble formation issues, which affect the reliability and quality of ink droplet release.
Innovation Solution
Incorporating an electrical impedance sensor to detect impedance values during the formation and collapse of drive bubbles within the fluid ejection device, allowing for real-time monitoring and servicing of the fluid actuator through a microfluidic pump and service station to address detected defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If real-time monitoring of drive bubble formation is implemented using electrical impedance sensors, then detection precision of fluid ejection defects is improved, but device complexity increases
Solution Approach 1:
The electrical impedance sensor serves multiple functions: it monitors drive bubble formation, detects particle blockages, identifies pigment separation, and tracks fluid level changes. This multi-functionality improves detection precision across multiple defect types without proportionally increasing device complexity, as a single sensor type handles diverse monitoring needs.
Solution Approach 2:
The patent replaces mechanical or optical monitoring systems with electrical impedance sensing. This substitution enables real-time detection of fluid ejection defects through electrical measurements during drive bubble formation, achieving high detection precision while avoiding the complexity of mechanical sensors or optical systems.
2Reliability
If continuous monitoring during drive bubble formation is performed, then reliability of ink droplet release is improved, but use of energy increases
Solution Approach 1:
The electrical impedance sensor performs periodic measurements at critical stages of drive bubble formation rather than continuous monitoring. This periodic sampling approach maintains reliability by detecting defects at key moments while reducing energy consumption compared to uninterrupted monitoring throughout the entire bubble formation cycle.
Solution Approach 2:
The system uses feedback from impedance measurements to trigger servicing operations only when defects are detected. This feedback mechanism improves reliability by enabling timely corrections while conserving energy by avoiding continuous operation of servicing components, activating them only when needed based on real-time detection.
3Productivity
If servicing operations are performed based on detected impedance values, then productivity is improved through reduced defects, but loss of time occurs during servicing interruptions
Solution Approach 1:
The system performs preliminary detection of defects such as particle blockages and pigment separation during normal operation using impedance sensing. By identifying issues before they cause printing defects, the system enables proactive servicing that maintains productivity, as problems are addressed early rather than after quality degradation occurs.
Solution Approach 2:
The fluid ejection device incorporates self-service capabilities through automated detection and triggering of servicing operations based on impedance measurements. The system monitors its own state and initiates servicing when defects are detected, reducing the need for external intervention and minimizing productivity loss by maintaining continuous operation with automated quality control.
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 effective detection and servicing of fluid ejection devices, improving the reliability and quality of ink droplet release by identifying and correcting issues like particle blockages and pigment separation, thereby enhancing printing performance.
Implementation Method 1
detecting at least one impedance values during a plurality of stages of existence of a drive bubble in at least one firing chamber
Implementation Method 2
The resistive heater evaporates the water during firing of the resistive heater. The evaporated fluid component or components expand to form a drive bubble
Implementation Method 3
a resistive heater positioned within the chamber to evaporate a small amount of fluid within the firing chamber
Implementation Method 4
pumping the fluid within at least the one fluid ejection chamber using a microfluidic pump
Data Source
AI summary
A fluid ejection system may include a fluidic die comprising at least one fluid ejection device, at least one electrical impedance sensor to detect at least one impedance value during a plurality of stages of existence of a drive bubble in at least one firing chamber associated with the at least one fluid ejection device, and a service station wherein, based on the impedance values detected, the printing system services the at least one fluid actuator.