Web Position Detection Cycle for Ink Landing Accuracy
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Solution Overview
Problem
Inkjet printers face challenges in maintaining image quality due to fluctuations in web tension, which cause deviations in the landing position of liquid ink, especially in both the main scanning and sub-scanning directions, as the web expands and contracts, affecting the accuracy of ink placement.
Innovation Solution
An image forming apparatus equipped with a conveyor, web position detectors, and control circuitry that adjusts droplet landing positions and tension control based on detected web positions, with the web position detection cycle being at least twice the tension control cycle to account for expansion and contraction variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If tension control is applied to the web during conveyance, then the web position stability is improved, but the web expands and contracts due to tension fluctuations, causing landing position deviation
Solution Approach 1:
The system performs preliminary action by detecting web position at a cycle twice as fast as the tension control cycle, capturing the web position before tension fluctuations cause expansion or contraction. This allows the ink discharge timing to be adjusted in advance based on the detected position, compensating for the upcoming web dimensional changes due to tension variations.
Solution Approach 2:
The system implements feedback by continuously monitoring web position through the web position detector and using this information to adjust ink discharge timing. The detected web position feedback is processed by the controller to modify the discharge timing, creating a closed-loop control system that compensates for tension-induced position deviations.
2Speed
If web position detection is performed at the same cycle as tension control, then the response speed is improved, but the expansion and contraction of the web during the same cycle causes measurement inaccuracy
Solution Approach 1:
The system performs web position detection at a cycle twice as fast as the tension control cycle, capturing the web position before tension fluctuations cause expansion or contraction. This preliminary detection allows the system to know the web position in advance, enabling accurate timing adjustment for ink discharge despite the slower tension control response.
Data Source
AI summary
An image forming apparatus is configured to discharge droplets onto a web to form an image. The image forming apparatus includes a conveyor, a web position detector, and control circuitry. The conveyor is configured to convey the web while applying a tension to the web. The web position detector is configured to detect a position of the web during conveyance. The control circuitry is configured to adjust landing positions of the droplets onto the web in a main scanning direction and a sub-scanning direction in accordance with the position of the web detected by the web position detector and control the tension applied to the web by the conveyor. The web position detector is configured to detect the position of the web in a cycle that is at least twice a tension control cycle in which the control circuitry controls a magnitude of the tension.