Coating Roller Speed Correction for Uniform Liquid Application
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Solution Overview
Problem
Existing liquid discharge apparatuses face issues with uneven coating due to fluctuations in motor speed and torque, leading to inconsistent application of treatment agents on recording media, which affects image quality.
Innovation Solution
A coating device with a conveyor, driver, and digital-to-analog converter that calculates and applies a correction amount to the speed command value, ensuring consistent rotation speed of the coating roller by reflecting the correction during non-conveyance periods, thereby maintaining uniform coating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If motor speed is controlled using a digital-to-analog converter without correction, then the coating roller rotates to convey the medium, but the coating amount becomes uneven due to speed fluctuations
Solution Approach 1:
The system calculates a correction amount based on the relationship between the digital speed command value and the actual analog voltage output, then applies this correction in a feedback loop to compensate for D/A converter inaccuracies, ensuring stable coating roller speed and uniform coating
Solution Approach 2:
The system changes the speed command parameter by adding a calculated correction amount to the digital speed command value before conversion, adjusting the input parameter to compensate for systematic errors in the D/A converter and achieve accurate speed control
2Manufacturing precision
If the correction amount is reflected continuously, then speed accuracy improves, but coating uniformity deteriorates due to speed changes during conveyance
Solution Approach 1:
The system performs speed correction in advance during periods when the medium is not passing through the coating roller, preparing the corrected speed command value before conveyance begins, ensuring accurate speed control is ready without disrupting the coating process
Solution Approach 2:
The correction amount is calculated and applied periodically during non-conveyance periods rather than continuously during conveyance, creating a periodic correction cycle that maintains coating consistency while still achieving speed accuracy
Data Source
AI summary
A coating device includes a conveyor, a driver, circuitry, and a digital-to-analog converter. The conveyor includes a coating roller to coat a medium with a liquid while conveying the medium in a conveyance direction. The driver rotates the coating roller at a rotation speed. The circuitry outputs a speed command value as a digital value. The digital-to-analog converter converts the speed command value as the digital value into an analog voltage value. Further, the circuitry calculates a correction amount to correct the speed command value, reflects the correction amount in the speed command value when the medium is not passing through the coating roller, and applies the speed command value, as the analog voltage value corrected by the correction amount, to the driver to rotate the coating roller at the rotation speed to convey the medium.