Rotatable Frame Sheet Registration Decouples Skew and Lateral Shifts
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Solution Overview
Problem
Existing sheet registration systems often cause misalignment issues due to uneven nip rotation, which can lead to sheet damage and ineffective registration, especially when handling sheets of varying sizes, as the force and moment balance created by closely spaced nips can result in slip and degraded performance.
Innovation Solution
The system separates the registration process into 'de-skew' and 'lateral' corrections using separate processing steps, where the 'de-skew' process measures and corrects rotational misalignment by rotating a sub-frame with all rollers at the same speed, and the 'lateral' correction adjusts the image position computationally, avoiding the need for differential nip speeds and reducing mechanical stress on the sheet.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple nips rotate at different speeds to correct skew, then sheet alignment is improved, but sheet damage increases due to placed stresses
Solution Approach 1:
The patent divides the skew correction function into two independent stages: (1) a de-skew transport that rotates the sheet to correct skew, and (2) a marking transport that applies marks at the correct position. This segmentation allows each transport to operate independently without requiring differential nip speeds, thereby eliminating sheet damage while maintaining alignment precision.
Solution Approach 2:
The patent introduces an intermediary de-skew transport between the sheet feed and the marking transport. This intermediary device performs the skew correction function separately, allowing the marking transport to operate at constant speed without differential rotation, thus preventing sheet damage while achieving proper alignment.
2Manufacturing precision
If multiple nips rotate at different speeds to correct skew, then sheet alignment is improved, but system reliability decreases when nips cannot properly grip sheets
Solution Approach 1:
The patent segments the registration system into independent de-skew and marking functions. The de-skew transport handles skew correction while the marking transport handles precise mark placement. This segmentation ensures that if gripping issues occur, only one function is affected, maintaining overall system reliability.
Solution Approach 2:
The de-skew transport is designed to be dynamically adjustable in its rotational position, allowing it to accommodate sheets with various skew angles. This dynamic capability ensures reliable operation across different sheet conditions without requiring complex differential nip speed control.
3Device complexity
If closely spaced nips are used to correct skew, then device complexity is reduced, but manufacturing precision decreases due to force and moment balance issues
Solution Approach 1:
The patent separates skew correction from mark placement functions into different transports. This allows the use of simple, closely spaced nips in the de-skew transport without compromising precision, as the marking transport independently ensures accurate mark placement regardless of the de-skew transport's mechanical simplicity.
Data Source
AI summary
Alignment apparatuses include a frame and contact elements connected to the frame. The contact elements contact items that are to be transported in a processing direction relative to the frame. The contact elements are in permeant fixed positions relative to the frame, and do not move relative to the frame. Adjustable mounts are connected to the frame and move the frame in the processing direction and in a perpendicular cross-processing direction. A controller is electrically connected to the adjustable mounts, and the controller is adapted to control the adjustable mounts to simultaneously move the frame and all the contact elements in the cross-processing direction and the processing direction while rotating the frame. Methods laterally shift imaging on sheets that have had rotational correction performed by such alignment apparatuses.