Roller Speed Control for Tension Management in Printing Apparatus
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Solution Overview
Problem
Conventional printing apparatuses experience rapid changes in tension and conveyance amount during loop amount adjustments, leading to nonuniform printed images and degraded image quality due to rapid changes in tension acting on the rolled sheet.
Innovation Solution
A printing apparatus with a control unit that adjusts the command speed of rollers and operates the cutting unit to manage tension and loop formation, ensuring a gradual reduction in tension as the print medium approaches the end of the printing length, thereby preventing rapid changes in conveyance amount and maintaining image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If loop amount is reduced to suppress skewing and meandering, then conveyance accuracy is improved, but tension changes rapidly causing image nonuniformity
Solution Approach 1:
The patent applies dynamics by making the loop amount adjustable and variable during the printing process. The control unit dynamically changes the loop amount based on the printing state: maintaining a larger loop amount during active printing to ensure stable conveyance, and reducing it after printing completes. This dynamic adjustment resolves the contradiction by allowing the system to optimize for conveyance accuracy when needed while maintaining image uniformity during the critical printing phase.
Solution Approach 2:
The patent applies preliminary action by forming a sufficient loop before printing starts and maintaining it throughout the printing process. The control unit ensures that the loop amount is adequate before printing begins, which stabilizes the tension and prevents rapid changes during printing. This preliminary preparation of the loop structure prevents the harmful rapid tension changes that would otherwise occur when adjusting loop amount mid-process.
2Loss of time
If loop amount is reduced before cutting, then cutting timing is improved, but conveyance amount changes rapidly degrading image quality
Solution Approach 1:
The patent applies preliminary action by forming a sufficient loop before printing starts and maintaining it throughout the printing process. The control unit ensures that the loop amount is adequate before printing begins, which stabilizes the tension and prevents rapid changes during printing. This preliminary preparation of the loop structure prevents the harmful rapid tension changes that would otherwise occur when adjusting loop amount mid-process.
Solution Approach 2:
The patent applies dynamics by making the loop amount adjustable and variable during the printing process. The control unit dynamically changes the loop amount based on the printing state: maintaining a larger loop amount during active printing to ensure stable conveyance, and reducing it after printing completes. This dynamic adjustment resolves the contradiction by allowing the system to optimize for conveyance accuracy when needed while maintaining image uniformity during the critical printing phase.
Data Source
AI summary
A printing apparatus includes a feeding unit, a conveyance unit, a cutting unit, and a control unit. The conveyance unit nips the print medium conveyed from the feeding unit by a first roller and a second roller, and conveys the nipped print medium. The cutting unit cuts the print medium. The control unit: (1) performs control to make a command speed of the first roller lower than a command speed of the second roller until a printhead printing reaches near a trailing edge of a printing length after printing has started, (2) performs control to make the command speed of the first roller higher than the command speed of the second roller when the printing has reached near the trailing edge of the printing length, and (3) subsequently controls the cutting unit configured to cut the print medium.