Fluid Ejection Die Current Leakage Test
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Solution Overview
Problem
Fluid ejection systems face issues with current leakage between nozzle sensors, which compromises the measurement of drive bubbles and affects the accuracy of fluid ejection processes, particularly due to the close spacing of these sensors and potential electrical conduction.
Innovation Solution
A current leakage test is implemented using a control circuit that generates an alternating bias across the nozzle sensors, applying a high bias voltage to one control line and a low bias voltage to another, allowing for rapid determination of electrical isolation and detection of current leaks between sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If nozzle sensors are closely spaced to improve measurement capability, then measurement precision is improved, but current leakage between sensors occurs compromising reliability
Solution Approach 1:
A test voltage line is introduced as an intermediary element between the nozzle sensors. This test voltage line enables electrical isolation testing by applying a test voltage to one sensor while monitoring for current leakage to adjacent sensors, thus verifying electrical isolation without requiring physical separation of the closely spaced sensors
2Reliability
If a current leakage test is implemented to detect electrical conduction, then reliability is improved, but device complexity increases
Solution Approach 1:
The fluid ejection die performs self-diagnosis by incorporating a test voltage line and control circuit that enable it to automatically detect current leakage between its own nozzle sensors. The system tests its own electrical isolation properties without requiring external testing equipment, thus improving reliability while minimizing additional complexity
3Productivity
If rapid determination of electrical isolation is performed, then productivity is improved, but measurement precision may be compromised
Solution Approach 1:
Electrical isolation testing is performed as a preliminary action before fluid ejection operations begin. The test voltage line applies test voltages to nozzle sensors in advance to verify electrical isolation, ensuring that measurement precision is not compromised during subsequent operational measurements while maintaining high productivity through rapid pre-testing
Data Source
AI summary
Example implementations relate to current leakage testing of a fluid ejection die. For example, a fluid ejection die may include plurality of nozzles, each nozzle among the plurality of nozzles including a nozzle sensor and a fluid ejector. The plurality of nozzle sensors may comprise a first subset and a second subset, each nozzle sensor among the plurality of nozzle sensors of the first subset may be electrically coupled to a first control line by a respective switch among a first group of switches, and each nozzle sensor among the plurality of nozzle sensors of the second subset may be electrically coupled to a second control line by a respective switch among a second group of switches. The fluid ejection die may include a control circuit to perform a current leakage test of the plurality of nozzles using the first control line and the second control line.