Inkjet Printing Apparatus Speed Change Landing Position Control
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Solution Overview
Problem
Conventional inkjet printing apparatuses fail to maintain high-quality printing when the transporting speed of the printing medium changes, leading to displacement of ink droplet landing positions between upstream and downstream nozzles, resulting in print quality issues during acceleration or deceleration.
Innovation Solution
An inkjet printing apparatus with drive rollers, an encoder for speed measurement, and a controller that adjusts the speed difference between the upstream and downstream nozzles to maintain a constant relationship between their landing positions, ensuring consistent print quality during speed changes by controlling the dispensation timing and speed of the printing medium.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the downstream nozzle dispenses ink droplet with a time lag to compensate for the distance between nozzles during constant speed transport, then the landing positions of ink droplets from upstream and downstream nozzles can be made to agree, but during acceleration or deceleration the landing positions become displaced and print quality deteriorates
Solution Approach 1:
The patent applies dynamics by making the time lag between upstream and downstream nozzle dispensing dynamic rather than fixed. The control unit calculates and adjusts the time lag based on real-time acceleration or deceleration of the printing medium, allowing the system to adapt to changing speeds while maintaining landing position agreement. This resolves the contradiction by enabling both precise landing position control and adaptability during speed changes.
2Productivity
If printing is performed during acceleration or deceleration of the printing medium, then productivity increases, but the landing positions of ink droplets become displaced resulting in poor print quality
Solution Approach 1:
The patent implements feedback by using a detection unit to measure the acceleration or deceleration of the printing medium in real-time, and the control unit uses this feedback information to dynamically adjust the ink droplet dispensing timing. This closed-loop control ensures that landing position accuracy is maintained even during speed changes, enabling continuous printing without quality degradation.
3Adaptability or versatility
If the transporting speed of the printing medium is changed during printing, then adaptability improves, but the conventional fixed time lag control causes displacement of landing positions
Solution Approach 1:
The patent applies parameter changes by dynamically modifying the time lag parameter between upstream and downstream nozzle dispensing based on the detected acceleration or deceleration of the printing medium. Instead of using a fixed time lag, the system adjusts this parameter in real-time to compensate for speed changes, thereby maintaining landing position consistency while enabling adaptability to different printing conditions.
Data Source
AI summary
To provide an inkjet printing apparatus capable of continuing printing even during speed change of web paper WP, a transport controller of this invention controls drive rollers, and to make constant at each point of time during the speed change of the drive rollers, a speed difference which is a difference between a first speed which is a transporting speed of web paper when the upstream nozzle dispenses an ink droplet and a second speed which is a transporting speed of web paper when a downstream nozzle dispenses an ink droplet. In this way, a constant relationship is realized, at each point of time during the speed change of drive rollers, between a landing position on the web paper of the ink droplet relating to the upstream nozzle and a landing position on the web paper of the ink droplet relating to the downstream nozzle.