Drop Sensor Offset Calibration for Print Head Nozzles
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Solution Overview
Problem
Printing apparatuses face challenges in accurately monitoring nozzle health and alignment due to potential misalignment of drop sensors relative to nozzles, which can lead to incorrect detection of liquid drop ejection and nozzle functionality.
Innovation Solution
A controller determines the actual position of a drop sensor relative to the nozzles based on a sensor profile of signal characteristics from ejected liquid drops, calculates an offset from the predetermined position, and adjusts the sensor's position for subsequent operations to ensure accurate detection of nozzle performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a drop sensor is positioned at a predetermined location relative to nozzles, then the monitoring structure is simple, but the detection accuracy deteriorates due to potential misalignment
Solution Approach 1:
The system performs a preliminary calibration process before actual monitoring operations. During calibration, the controller ejects test drops from multiple nozzles while the drop sensor is at the predetermined position, and uses the resulting sensor profile to calculate an offset value. This preliminary action allows the system to compensate for potential misalignment without changing the physical sensor position, thus maintaining structural simplicity while improving detection accuracy.
Solution Approach 2:
The system changes the parameter of the sensor's effective detection position by calculating and applying an offset value. Instead of physically moving the sensor to correct misalignment, the system modifies the parameter of position through software correction. The controller uses the calculated offset to adjust the determination of which nozzle corresponds to which sensor reading, thereby compensating for the predetermined position偏差 and maintaining high detection accuracy.
2Measurement precision
If the drop sensor position is corrected by physical movement, then detection accuracy improves, but the calibration process becomes more complex
Solution Approach 1:
The system replaces the mechanical approach of physically moving or adjusting the sensor position with an information-based approach. Instead of using mechanical calibration methods to reposition the sensor, the system uses software-based offset calculation and compensation. The controller processes sensor profile data to determine the offset and applies this correction algorithmically, substituting mechanical complexity with computational simplicity and achieving the same accuracy improvement.
3Ease of operation
If nozzle monitoring is performed without offset correction, then the operation is simple, but the reliability of nozzle health detection deteriorates
Solution Approach 1:
The system performs self-calibration automatically without requiring manual intervention or complex external equipment. The controller uses the sensor profile obtained during normal operation to calculate the offset value and apply corrections autonomously. This self-service capability maintains operational simplicity while significantly improving the reliability of nozzle health detection by automatically compensating for position deviations.
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 method enhances the accuracy of nozzle health monitoring and liquid drop detection, allowing for timely identification of non-functional nozzles and improving print quality by accounting for sensor misalignment.
Implementation Method 1
a drop sensor to detect flying liquid drops ejected by at least some of the nozzles
Data Source
AI summary
A printing apparatus may comprise a print head including nozzles to eject liquid drops, a drop sensor to detect flying liquid drops ejected by at least some of the nozzles, and a controller. The controller is to control at least some of the nozzles to sequentially eject liquid drops while the drop sensor is at a predetermined position relative to the nozzles, to determine the actual position of the drop sensor relative to the nozzles based on a sensor profile including a nozzle location specific signal characteristic of the sequentially ejected liquid drops detected by the drop sensor, and to calculate an offset between the determined actual position and the predetermined position. The controller may take the offset into account in positioning the drop sensor relative to one of the nozzles to detect a liquid drop ejected from that nozzle in a subsequent operation.