Liquid Ejecting Apparatus Transition Speed Control
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Solution Overview
Problem
Conventional liquid ejecting apparatuses face challenges in maintaining image quality when the recording medium is transferred from one conveying roller to another, due to variations in conveying speed, leading to liquid ejection deviations from the prescribed landing position.
Innovation Solution
A liquid ejecting apparatus with a first and second conveying device, a liquid ejecting head, and a transition period setting device, which adjusts the liquid ejecting timing based on varying conveying speeds to ensure accurate ink droplet placement during transitions between conveying sections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If liquid ejection timing is controlled based on encoder signals from conveying rollers, then liquid ejection positioning accuracy is improved, but image quality degrades during transition periods when conveying speed varies
Solution Approach 1:
The patent introduces a transition period detection mechanism that dynamically identifies when the recording medium is being transferred between conveying rollers. During this transition period, the system switches from using encoder-based timing (which assumes constant speed) to a different timing control mode that accounts for speed variations, thereby maintaining image quality consistency throughout the entire conveying process
Solution Approach 2:
The patent changes the control parameter from fixed encoder-based timing to a dynamic timing mechanism that detects transition periods and adjusts ejection timing accordingly. By monitoring the phase difference between encoder signals and identifying when it exceeds a threshold, the system adapts its timing control to maintain accuracy during both steady-state and transition periods
2Adaptability or versatility
If conveying speed varies during roller transfer, then conveying flexibility is improved, but liquid landing position accuracy deteriorates
Solution Approach 1:
The patent implements a transition period detection mechanism that identifies upcoming speed changes before they occur. By detecting when the phase difference between encoder signals exceeds a threshold, the system proactively switches to an appropriate timing control mode, ensuring that liquid ejection positioning remains accurate even as conveying speed is about to change during roller transfer
Data Source
AI summary
In a liquid ejecting apparatus, a recording medium is conveyed by only a first conveying device during a first period, by only a second conveying device during a second period, and by both the first and second conveying device during a third period. The recording medium is conveyed, in theory, at first and second conveying speeds during the first and second periods respectively. A transition period is set from the first period to the third period or from the third period to the second period. The head controller controls a ejecting head during a period prior to the transition upon assuming that the conveying speed is the first conveying speed, during a period after the transition upon assuming that the conveying speed is the second conveying speed, and during the transition period upon assuming that the conveying speed is a third conveying speed between the first and second conveying speeds.