Print Head Nozzle Condition Evaluation via Impedance Measurement
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Solution Overview
Problem
Inkjet printing systems face challenges in maintaining print quality due to nozzle defects, such as clogging and improper ink drop formation, which can be caused by particulate matter or solidified ink, leading to issues with drive bubble formation and collapse, requiring effective monitoring and maintenance to prevent print quality degradation.
Innovation Solution
A minimal circuit is implemented on the print head to evaluate nozzle conditions by measuring impedance variations at predetermined time instants, using a single timing circuit shared among nozzle columns and separate drive bubble detect circuits for each column, allowing on-chip determination of nozzle health without the need for off-chip signal processing, thereby reducing bandwidth demand and avoiding noise interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a minimal circuit is implemented on the print head for evaluating nozzle conditions, then measurement precision and reliability are improved, but device complexity increases
Solution Approach 1:
The patent combines multiple evaluation functions into a single integrated circuit implemented on the print head. The circuit integrates impedance sensing, timing control, and evaluation logic into one unified structure, allowing comprehensive nozzle condition monitoring without requiring separate external components for each function.
Solution Approach 2:
The evaluation circuit is designed to perform multiple functions: it can evaluate individual nozzles, entire nozzle columns, and provide both diagnostic and control capabilities. The same circuit infrastructure supports different evaluation modes and can adapt to various nozzle configurations, maximizing the utility of the added complexity.
2Measurement precision
If impedance measurements are taken at multiple predetermined time instants, then measurement precision is improved, but loss of time increases
Solution Approach 1:
The circuit performs impedance measurements at specific periodic intervals corresponding to key moments in the drive bubble lifecycle. Rather than continuous monitoring, it samples at predetermined time instants when the drive bubble forms and collapses, capturing critical information efficiently without constant measurement overhead.
Solution Approach 2:
The evaluation circuit is pre-configured with predetermined time instants for measurement based on expected drive bubble behavior. This preliminary setup allows the system to know exactly when to measure, eliminating the need for real-time analysis or adaptive timing decisions during operation.
3Device complexity
If a single timing circuit is shared among nozzle columns, then device complexity is reduced, but reliability may worsen due to potential signal interference
Solution Approach 1:
The patent divides the nozzle system into separate nozzle columns, each with its own dedicated evaluation circuit. While a single timing circuit provides overall coordination, each nozzle column has independent sensing and evaluation paths, preventing signal interference between columns while maintaining centralized timing control.
4Loss of time
If on-chip determination of nozzle health is implemented, then loss of time is reduced, but device complexity increases
Solution Approach 1:
The patent merges signal acquisition, processing, and evaluation functions into a single on-chip circuit. Rather than having separate components for generating test signals, measuring impedance, and analyzing results, all these functions are integrated into one circuit block that operates directly on the print head, eliminating external processing delays.
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 enables efficient and accurate monitoring of nozzle conditions, reducing the need for complex processing and communication, minimizing electrical noise interference, and facilitating timely maintenance to maintain print quality, while also reducing resource usage and circuit complexity.
Implementation Method 1
measuring an impedance associated with the nozzle at a first predetermined time instant and a second predetermined time instant
Data Source
Figure 1a
Figure 1b
Figure 1c
AI summary
The present subject matter relates to evaluating print head nozzle condition of a plurality of nozzle columns. Each of the plurality of nozzle columns comprises a set of nozzles. A plurality of drive bubble detect modules are activated, by a timing circuit coupled to each of the plurality of nozzle columns upon occurrence of at least a first predetermined time instant and a second predetermined time instant. For each of the plurality of nozzle columns, test results for a nozzle of the nozzle column are registered by the corresponding drive bubble detect module. Test results obtained based on impedances measured across a nozzle associated with the nozzle column corresponding to a drive bubble detect module are registered by the drive bubble detect module at the first predetermined time instant and the second predetermined time instant. The print head nozzle condition of the nozzle is evaluated based on the test results.