Sheet Alignment Servo Control with Position Compensation

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Solution Overview

Problem

Existing sheet synchronization systems fail to positively control the alignment of both left and right sheets relative to each other and do not account for the initial alignment of sheets received from an upstream module, leading to misalignment issues during the sheet transition through the hold module.

Innovation Solution

A system using photocells and servo motors with encoders to capture the angular displacement of sheets and adjust their position incrementally, ensuring accurate alignment by calculating the initial alignment offset and applying correction distances to each sheet during its transition through the hold module.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a velocity motion profile is used to adjust sheet alignment by acceleration and deceleration, then sheet alignment at the downstream module is improved, but the control complexity increases and cannot account for initial alignment variations

Engineering Contradiction:

Improvesheet alignmentVSAvoidmotion profile configuration

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The system performs preliminary measurement of the initial alignment offset between sheets at the hold module entry using photocells before the sheets enter the alignment adjustment process. This preliminary action allows the system to know the starting alignment condition and plan the necessary adjustments, rather than relying on complex velocity profiles that attempt to correct alignment after the fact.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system uses photocells to detect the presence and position of sheets, encoders to measure servo motor position, and a control computer to calculate the initial alignment offset based on encoder pulse differences. This feedback loop provides real-time information about sheet alignment status, enabling precise control adjustments without complex predetermined motion profiles.

Inventive Principle:

Principle #23Feedback

2Manufacturing precision

If separate servo motor position control is implemented for both left and right sheets, then positive control of both sheets' alignment is improved, but the device complexity increases

Engineering Contradiction:

Improvealignment controlVSAvoidservo motor control system

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The system divides the sheet transport into separate parallel paths (left and right sheets) with independent servo motor control for each path. This segmentation allows each sheet to be controlled independently, enabling precise alignment adjustment of both sheets relative to each other while maintaining simple control logic through modular independent control.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system replaces complex mechanical alignment mechanisms with servo motor position control systems. Each sheet transport path has a servo motor with an encoder that provides electronic position control, substituting mechanical alignment devices with electronically controlled systems that are more precise and easier to program for alignment correction.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If encoder pulses are used to measure sheet position, then measurement precision is improved, but the system cannot account for initial alignment offset from the cutter

Engineering Contradiction:

Improvesheet position measurementVSAvoidaccounting for initial alignment

Core Design Contradiction:

Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The control computer receives encoder pulse values from both left and right sheet servo motors and uses this feedback to calculate the initial alignment offset. By comparing the encoder pulse counts from both sides when sheets enter the hold module, the system determines the alignment difference and adjusts subsequent positioning commands to achieve proper alignment, making the system adaptable to various initial alignment conditions from the cutter.

Inventive Principle:

Principle #23Feedback

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The system effectively adjusts the alignment of sheets to meet the requirements of downstream modules, ensuring proper overlap and preventing misalignment, which reduces the risk of jams and paper damage, while maintaining smooth paper handling and constant velocity.

Implementation Method 1

First and second photo sensors are configured to detect a presence of first and second sheets at respective sheet transport entry points

Methodology Applied

Scientific EffectPhotoelectric Effect: Photoelectric Effect

Implementation Method 2

each servo motor including an encoder configured to generate encoder pulses for each rotation of the servo motors

Methodology Applied

Scientific EffectEncoder feedback:

Data Source

PatentUS9540203B2Method and system for synchronizing items using position compensation

Publication Date: 2017.01.10 BELL & HOWELL CO

AI summary

The present applications relates to techniques and equipment to control the alignment of cut sheets of paper that are transported in parallel in an inserting system prior to their assembly into a document and inserted into an envelope. The alignment of the parallel sheets is adjusted by commanding incremental position changes to servo drive motors used to control the position of the parallel sheets during their transport through a hold module of the inserting system.