Misregistration Detection Pattern for Image Forming Apparatus
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Solution Overview
Problem
Existing image forming apparatuses face challenges in accurately detecting misregistration due to uneven driving of photosensitive drums and conveying belt rollers, leading to increased downtime and costs, especially in small devices where conventional misregistration detection patterns cannot be arranged within the limited peripheral length of the conveying belt.
Innovation Solution
The apparatus employs a configuration with a misregistration detection pattern comprising serial first and second patterns of different shapes and color orders, which are strategically arranged to average and cancel the driving unevenness caused by both the photosensitive drum and the conveying belt rollers, allowing for precise detection without requiring extensive peripheral length or high-cost sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional misregistration detection patterns are arranged to cancel driving unevenness, then measurement precision is improved, but the patterns cannot be arranged within one periphery of the conveying belt in small image forming apparatus, requiring increased downtime for cleaning
Solution Approach 1:
The misregistration detection pattern is divided into multiple individual patterns arranged at different positions along the conveying belt. Each pattern is detected separately by optical sensors, and the detection results are processed to calculate misregistration amounts. This segmentation allows patterns to be distributed over multiple peripheries rather than requiring all patterns to fit within one periphery, eliminating the need for cleaning operations.
Solution Approach 2:
The invention transitions from arranging all detection patterns within the single-dimensional constraint of one conveying belt periphery to utilizing multiple peripheries (extending along the conveying direction). By distributing patterns across different positions that span multiple peripheries, the system achieves the required pattern arrangement without requiring cleaning operations, effectively adding the dimension of multiple revolutions to the pattern layout.
2Loss of time
If misregistration detection patterns are arranged within one periphery of the conveying belt, then downtime is reduced, but driving unevenness cannot be effectively averaged and canceled
Solution Approach 1:
The detection pattern is segmented into multiple individual patterns positioned at different locations along the conveying belt. These segmented patterns are distributed across multiple peripheries, allowing the system to achieve both reduced downtime (by not requiring cleaning) and improved measurement precision (by averaging driving unevenness across multiple positions and revolutions).
Solution Approach 2:
The system utilizes periodic revolution of the conveying belt to pass multiple detection patterns past the optical sensors. By detecting patterns at different positions during multiple peripheries, the system periodically samples the misregistration at various points, enabling effective averaging of driving unevenness while maintaining continuous operation without cleaning downtime.
3Measurement precision
If high-density misregistration detection patterns are arranged within one periphery using special sensors, then measurement precision is improved, but device cost increases
Solution Approach 1:
Instead of using special high-cost sensors with small spot diameters to achieve high-density pattern detection within one periphery, the invention segments the detection task across multiple peripheries using conventional sensors. This approach maintains measurement precision by distributing detection points while avoiding the need for expensive specialized sensor components.
Solution Approach 2:
The invention resolves the cost issue by transitioning from a single-periphery high-density arrangement (requiring expensive sensors) to a multi-periphery distributed arrangement using conventional sensors. By extending the pattern detection along the conveying direction across multiple revolutions, the system achieves equivalent or superior precision without increasing sensor costs.
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
This approach enables highly precise misregistration detection, reducing downtime and costs by effectively averaging and canceling driving unevenness, while extending the applicability to smaller image forming apparatuses with shorter conveying belt peripheries.
Implementation Method 1
The positions of the patterns are detected by a pair of optical sensors provided on both sides of the conveying belt on the downstream unit
Data Source
AI summary
This invention enables an image forming apparatus to perform highly precise misregistration detection without causing increased downtime or increased cost. For this, the image forming apparatus according to the invention comprises a detection unit for detecting a misregistration detection pattern formed on an endless belt. The employed misregistration detection pattern includes a first pattern array formed with a misregistration detection color or a reference position color, and a second pattern array formed with a misregistration detection color or a reference position color. The misregistration detection pattern is configured in a way that the first pattern and the second pattern have different shapes, and that the color order of the first patterns in the first pattern array and the color order of the second patterns in the second pattern array are different.