Inkjet Edge Sensor Failure Detection via Output Combination
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Solution Overview
Problem
Inkjet recording apparatuses face precision issues in color superimposition due to sheet wobble, leading to erroneous sensor failure detection and subsequent downtime, which decreases productivity.
Innovation Solution
The apparatus includes multiple line heads with edge sensors and actuators to detect and adjust for sheet edge positions, preventing erroneous sensor failure detection by distinguishing between wobble and positional changes, and using a controller to determine sensor failures based on output combinations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single sensor is used to detect wobble and index, then device complexity is reduced, but measurement precision and reliability deteriorate due to inability to distinguish between wobble output and index output
Solution Approach 1:
The patent divides the detection function into separate components: a single sensor detects both wobble and index, but the controller segments the processing by using different detection methods and thresholds for each function. The wobble detection uses amplitude-based analysis while index detection uses position-based analysis, allowing precise distinction despite using a single sensor.
Solution Approach 2:
The controller acts as an intermediary that processes the sensor output through multiple stages. It first detects the sensor signal, then applies different processing algorithms (amplitude thresholding for wobble, position tracking for index) to distinguish between the two types of signals, preventing erroneous failure detection.
2Manufacturing precision
If wobble detection sensitivity is increased to improve color superimposition precision, then manufacturing precision improves, but false sensor failure detection increases
Solution Approach 1:
The patent changes the detection parameters dynamically. For wobble detection, it uses amplitude thresholds and frequency analysis. For index detection, it uses position-based criteria. By adjusting these parameters based on the type of signal being analyzed, the system achieves high precision for color superimposition while avoiding false sensor failure detections.
Solution Approach 2:
The system continuously monitors sensor output and provides feedback to the controller. The controller analyzes the feedback signal characteristics (amplitude, position, frequency) to determine whether the output represents wobble, index, or actual sensor failure, enabling accurate distinction and preventing false alarms.
3Measurement precision
If multiple edge sensors are used to improve measurement precision, then color superimposition precision improves, but device complexity and failure detection difficulty increase
Solution Approach 1:
The patent merges the functionality of multiple edge sensors into a single sensor by processing the output through the controller. Instead of using multiple sensors to detect edge positions, the system uses one sensor and analyzes its output signal characteristics to achieve the same detection precision, thereby reducing device complexity.
4Reliability
If sensor output thresholds are set high to prevent false failures, then reliability improves, but measurement precision for wobble detection deteriorates
Solution Approach 1:
The patent applies dynamic thresholding where the controller adjusts detection thresholds based on the current operating conditions and signal characteristics. For wobble detection, it uses lower amplitude thresholds to capture subtle movements. For index detection, it uses position-based thresholds. This dynamic adjustment maintains both high reliability and precision across different detection scenarios.
Data Source
AI summary
An inkjet recording apparatus includes a plurality of line heads disposed along a conveyance direction of a recording sheet and including a plurality of nozzles to discharge ink droplets, the plurality of nozzles disposed in a direction perpendicular to the conveyance direction of the recording sheet; a plurality of edge sensors corresponding to respective line heads, to detect a lateral edge of the recording sheet; a plurality of actuators corresponding to the respective line heads, to move to the respective line heads laterally in a sheet width direction; a head position adjustor to determine movement amounts of the respective line heads in accordance with outputs of the plurality of edge sensors; and a failure determiner to obtain outputs of the plurality of edge sensors simultaneously and identify a failure of the plurality of edge sensors based on a combination of the outputs from the plurality of edge sensors.