Trimming Shorted Fluid Ejector Units in Inkjet Modules
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Solution Overview
Problem
Fluid ejection modules, such as those in ink jet printers, often suffer from electrical shorts in the electrode of fluid ejector units, which can compromise the driving circuitry and render the module unusable, necessitating a method to isolate or repair these shorted units.
Innovation Solution
The method involves determining shorted fluid ejector units through capacitance measurement, optical microscopy, or thermal imaging, and then trimming the affected electrodes or bond pads to electrically isolate them, thereby disabling or partially restoring the units to function.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrical shorts in fluid ejector units are not addressed, then the module remains operational, but the driving circuitry is compromised or damaged
Solution Approach 1:
The patent applies segmentation by dividing the conductive layer into separate segments corresponding to individual fluid ejector units. When a short is detected in one unit, only that specific segment is severed, isolating the fault to a single ejector unit while preserving the functionality of other units and protecting the driving circuitry from damage.
Solution Approach 2:
The patent extracts the harmful shorted segment from the overall conductive network by selectively severing the conductive layer at the location of the short. This removes the damaging electrical path while maintaining the integrity of the remaining conductive structures and driving circuitry.
2Reliability
If the entire conductive layer is severed to isolate a short, then the short is isolated from driving circuitry, but all fluid ejector units are disabled
Solution Approach 1:
The conductive layer is segmented into multiple independent regions, each serving a specific fluid ejector unit. This segmentation allows selective isolation of only the shorted unit by severing only the relevant conductive segment, rather than disabling the entire conductive network and all ejector units.
Solution Approach 2:
The patent applies local quality by making the conductive layer structure such that different segments have different functional assignments. Each segment corresponds to a specific ejector unit, allowing localized repair or isolation actions to be performed on individual segments without affecting the global system functionality.
3Productivity
If shorted fluid ejector units are not trimmed, then module functionality is maintained, but printing defects occur and driving circuitry is at risk
Solution Approach 1:
The patent implements preliminary action by detecting electrical shorts and trimming the conductive layer during the manufacturing or initialization phase, before the module is put into full operational use. This preliminary corrective action prevents future printing defects and protects the driving circuitry from potential damage.
Solution Approach 2:
The system uses electrical testing to detect shorts in fluid ejector units and provides feedback that triggers the trimming process. This feedback mechanism ensures that defective units are identified and corrected, maintaining high printing quality and preventing circuitry damage.
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
This approach effectively reduces printing defects by isolating or repairing shorted fluid ejector units, preventing damage to the driving circuitry and maintaining module functionality.
Implementation Method 1
The piezoelectric actuator can have a layer of piezoelectric material that changes geometry, or flexes, in response to an applied voltage. Flexing of the piezoelectric layer causes a membrane to flex, where the membrane forms a wall of the pumping chamber.
Implementation Method 2
Trimming may be performed by a laser, an etch process, by an ion beam, or by mechanical cutting.
Data Source
AI summary
A fluid ejector includes a plurality of fluid ejector units, each fluid ejector unit characterized in part by a pumping actuator that includes an electrode. Whether one or more of the plurality of fluid ejector units is a shorted fluid ejector unit is determined, and the shorted fluid ejector unit is trimmed.