Dynamic Nip Load Control for Skew Correction in Printers
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Solution Overview
Problem
Existing printing apparatuses face challenges in maintaining optimal nip load for registration roller pairs, leading to print quality degradation due to issues with skew correction and ink transfer, especially when dealing with varying medium grammage and types.
Innovation Solution
A printing apparatus with a controller that adjusts the nip load based on print job information, including medium type and grammage, to optimize contact between the registration roller pair and paper, reducing print quality degradation by switching the nip load during transport operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the pressing force of the registration roller pair is increased to correct skewing, then skew correction capability is improved, but the sheet transport speed changes undesirably and print quality degrades
Solution Approach 1:
The pressing force of the registration roller pair is made dynamically adjustable rather than fixed. The controller increases pressing force during skew correction phase and reduces it during normal transport phase, allowing the system to adapt its characteristics to different operational requirements and resolve the contradiction between skew correction quality and transport speed stability
Solution Approach 2:
The controller applies pressing force preliminarily and selectively - increasing it only when skew correction is needed (detected via leading edge position sensing) and reducing it when not needed. This preliminary action approach ensures pressing force is applied only during the specific phase requiring skew correction, preventing unnecessary impact on transport speed
2Productivity
If the pressing force of the registration roller pair is reduced to maintain stable transport speed, then transport speed stability is improved, but skew correction capability deteriorates
Solution Approach 1:
The system dynamically adjusts pressing force based on real-time detection of sheet leading edge position. When skew is detected, pressing force increases to enable correction; when no skew is present, pressing force reduces to maintain stable transport speed. This dynamic adaptation resolves the contradiction by allowing both high-speed stable transport and effective skew correction at different times
3Object-affected harmful factors
If the pressing force of the registration roller pair is increased to prevent ink transfer, then ink transfer prevention is improved, but print quality degrades due to excessive pressing on printed areas
Solution Approach 1:
The controller reduces pressing force preliminarily before the printed area reaches the registration roller pair, and only applies increased pressing force when the leading edge (non-printed area) is being processed. This timing-based control prevents ink transfer during critical phases while protecting printed quality by avoiding excessive pressing on printed regions
Solution Approach 2:
The system applies different pressing force levels to different spatial regions and time phases of sheet transport. High pressing force is applied locally during leading edge processing for skew correction and ink transfer prevention, while low pressing force is applied during printed area transport to protect print quality. This localized quality approach resolves the contradiction between ink transfer prevention and print quality maintenance
4Manufacturing precision
If the pressing force of the registration roller pair is reduced to protect printed areas, then print quality is improved, but skew correction capability and ink transfer prevention deteriorate
Solution Approach 1:
The pressing force is dynamically controlled based on the position and state of the sheet. The controller detects leading edge position and adjusts pressing force accordingly - increasing it for skew correction and ink transfer prevention, then reducing it before printed areas arrive. This dynamic control allows the system to maintain both effective skew correction/ink transfer prevention and high print quality by applying appropriate force at appropriate times
Data Source
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AI summary
A printing apparatus (11) includes a print section (17) to perform printing on a medium (14), a supply path (26) to supply the medium to the print section, a correction roller pair (33) to enable the medium transported on the supply path to strike the correction roller pair to correct skewing of the medium, an adjusting mechanism for adjusting a nip load applied to the correction roller pair, and a controller to control the adjusting mechanism based on print job information.