Sheet Transport Control for Image Registration in Printers
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Solution Overview
Problem
In image forming apparatuses, deviations in image transfer due to positional and speed variations during the sheet transport process lead to reduced image quality, as existing technologies fail to effectively correct for these deviations in real-time, resulting in issues like density irregularity and magnification errors.
Innovation Solution
A transport medium driving device that includes a position detecting unit, a positional deviation acquiring unit, a correcting unit, and a determining unit to monitor and correct positional deviations in real-time, ensuring precise alignment and speed control of the sheet transport medium, thereby improving image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the sheet transport speed is adjusted using a predetermined speed profile to synchronize image and sheet arrival at the transfer position, then the timing alignment is improved, but the system cannot account for real-time positional deviations and vibrations, leading to image quality degradation
Solution Approach 1:
The patent implements a feedback control system where a sensor detects the actual position of the sheet during transport, and this detection information is fed back to a control unit that adjusts the sheet transport speed in real-time. This closed-loop feedback mechanism enables the system to correct positional deviations dynamically, ensuring both precise timing alignment and high image quality without the limitations of predetermined speed profiles.
2Stability of the object's composition
If the gradient of the speed profile is reduced to minimize vibration in the sheet transport control system, then the stability is improved, but the time required to synchronize image and sheet arrival increases, reducing printing speed
Solution Approach 1:
The patent employs dynamic speed adjustment where the sheet transport speed is continuously optimized based on real-time position detection. Rather than using a fixed, conservative speed profile gradient, the system dynamically modifies the speed profile to achieve synchronization while minimizing vibration. This dynamic approach allows for faster correction of positional deviations, maintaining system stability while improving printing speed and productivity.
3Ease of operation
If a predetermined speed profile is used to adjust sheet transport speed, then the implementation is simple, but the system cannot correct for real-time positional deviations, causing image deviation and magnification errors
Solution Approach 1:
The patent replaces the open-loop predetermined speed profile approach with a closed-loop feedback control system. The sensor continuously monitors the sheet position, and the control unit processes this information to dynamically adjust the transport speed. This feedback mechanism maintains ease of operation through automated control while dramatically improving image accuracy by correcting real-time positional deviations, eliminating the trade-off between simplicity and precision.
4Productivity
If the sheet transport control system operates without convergence of correction operations, then the processing speed is maintained, but density irregularity and image deviation occur, reducing image quality
Solution Approach 1:
The patent implements a feedback control system with convergence determination functionality that monitors whether the correction operations have stabilized. The control unit continuously adjusts the sheet transport speed based on detected positional deviations and determines when the correction has converged. This ensures that correction operations are completed accurately to prevent density irregularity and image deviation, while the automated nature of the feedback control maintains high processing speed without manual intervention.
Data Source
AI summary
A transport medium driving device is provided with a transport unit that transports a sheet-shaped transport medium on which an image is formed by an image forming unit, a position detecting unit that detects the position of the sheet-shaped transport medium, a positional deviation acquiring unit that acquires a positional deviation between the detected position and a predetermined target position at a predetermined interval, a correcting unit that corrects the positional deviation on the basis of a correction amount for correcting a positional displacement between the sheet-shaped transport medium and the image formed on the sheet-shaped transport medium, a control unit that controls a transport speed of the sheet-shaped transport medium on the basis of the corrected positional deviation, and a determining unit that determines whether a correction operation is converged on the basis of a variation in the positional deviation over time.