Inkjet Printhead Nozzle Condition Detection via Internal Electrodes
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Solution Overview
Problem
Current methods for detecting the condition of inkjet printhead nozzles are inefficient and require external devices or complex calibration, making them impractical for use in high-speed printing applications where multi-pass printing is not feasible.
Innovation Solution
A fluid printhead system with a common first electrode shared by multiple fluid chambers and individual second electrodes, using a sense circuit to detect the presence of ink through a digital output, allowing for simultaneous stimulation and condition sensing of multiple nozzles on a single bus line.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical detection methods are used to detect nozzle condition, then detection capability is improved, but device complexity and cost increase due to external light sources and sensors
Solution Approach 1:
The printhead uses its own internal structures (heater elements, fluid chambers, throat portions) as electrodes for detection, eliminating the need for external optical detection devices. The system serves its own detection needs using inherently present components.
Solution Approach 2:
The heater element and cavitation protection layer serve dual functions: heating the fluid for ejection and acting as electrodes for condition detection. This multi-functionality reduces the number of separate components needed.
2Device complexity
If impedance sensors are placed on the ejector chip to eliminate external devices, then device complexity is reduced, but detection efficiency decreases due to requiring analysis of each sensor output at each ink chamber
Solution Approach 1:
Multiple detection channels are merged into a single detection system where a step voltage applied to the common first electrode stimulates multiple fluid chambers simultaneously, and the response is detected through the shared electrode structure, enabling parallel detection of multiple nozzles.
Solution Approach 2:
The detection system is segmented into independent fluid chambers each with their own second electrode, allowing individual nozzle conditions to be detected while sharing common infrastructure (first electrode, stimulus node).
3Measurement precision
If conventional impedance measurement methods are used, then nozzle condition can be detected, but calibration is required which adds complexity and time to the detection process
Solution Approach 1:
The system uses the natural electrical response of the ink chamber (presence or absence of conductive ink) to provide self-diagnostic information without requiring external calibration procedures. The detection is inherently calibrated to the physical properties of the ink itself.
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 a practical and efficient method for determining the condition of inkjet printhead nozzles without external devices, reducing complexity and cost, and allowing for rapid detection of nozzle failures in high-speed printing.
Implementation Method 1
each fluid ejection element comprises a corresponding fluid chamber, throat portion and heater element
Implementation Method 2
detect the formation and collapse of thermal vapor bubbles
Implementation Method 3
a cavitation protection layer as an electrode in a condition detection cell
Implementation Method 4
The output of the sense circuit is a digital low output upon a condition that fluid is present in the fluid chamber
Data Source
AI summary
A fluid printhead (10) including at least one fluid ejection element (100). The fluid ejection element (100) includes a fluid chamber (102), a throat portion through which fluid is provided to the fluid chamber (102), and a heating element (104) disposed within the fluid chamber (102). The fluid ejection element (100) also includes a printhead condition detection system (120). The printhead condition detection system (120) includes a first electrode (106) at least a portion of which is disposed within the fluid chamber (102), the first electrode (106) configured to receive a step voltage, a second electrode (110) disposed within the throat portion, and a sense circuit (112) electrically connected to the second electrode (110) that generates an output based on the application of the step voltage to the first electrode (106) as an indication of printhead condition.