Registration-less Unit Skew Correction via Speed Adjustment
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Solution Overview
Problem
Conventional image forming devices rely on registration rollers to correct sheet skew, which can cause sheet warping and require temporary cessation of sheet conveyance, leading to inefficiencies and potential misalignment during the printing process.
Innovation Solution
An image forming device with a registration-less unit that includes a pair of registration-less rollers and a moving mechanism, controlled by an engine control unit, which adjusts the sheet conveyance speed and corrects skew without stopping the sheet, using a line sensor to detect sheet inclination and adjust the speed change timing based on deviation amounts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If registration rollers are used to correct sheet skew, then skew correction is achieved, but sheet warping occurs and conveyance must be temporarily stopped
Solution Approach 1:
The patent applies preliminary action by detecting sheet skew at an upstream position (first position) before the sheet reaches the image forming unit, and calculating correction amounts in advance. This allows the sheet conveyance speed to be adjusted proactively at a second position downstream, correcting skew without stopping the conveyance process and preventing sheet warping that would occur with traditional registration rollers.
2Manufacturing precision
If registration rollers stop to correct skew, then alignment is improved, but processing time increases
Solution Approach 1:
The patent implements continuity of useful action by maintaining continuous sheet conveyance throughout the skew correction process. Instead of stopping the sheet at registration rollers, the system continuously feeds the sheet while dynamically adjusting the conveyance speed based on real-time skew detection and calculated correction amounts, thereby achieving alignment without time loss from interruptions.
3Manufacturing precision
If traditional skew correction is used, then skew is corrected, but printing position variation occurs
Solution Approach 1:
The patent applies feedback by using a line sensor to detect the actual skew state of the sheet at the first position, calculating the required correction amount based on this feedback, and then adjusting the sheet conveyance speed accordingly at the second position. This closed-loop feedback mechanism ensures accurate skew correction while maintaining consistent printing position, preventing the position variations that occur with traditional open-loop registration roller methods.
Data Source
AI summary
An image forming device includes an image forming unit, a reading unit, a registration-less unit, and an engine control unit. The reading unit reads a sheet to be conveyed. The engine control unit moves the other end side of the registration-less unit to correct skew. The engine control unit obtains a deviation amount (first deviation amount) of the position of the sheet based on the correction, and changes a sheet conveyance speed from a first speed to a second speed when the sheet enters the registration-less unit. The engine control unit adjusts the timing to change from the first speed to the second speed based on the first deviation amount.