Image Density Control via Interleaved Measurement Images
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Solution Overview
Problem
Conventional image forming apparatuses face challenges in maintaining consistent image density, especially when continuously forming images on long sheets, as the time interval for adjusting image forming conditions becomes longer, leading to variations in image density.
Innovation Solution
The apparatus includes a conveyance roller, an image forming unit, a sensor, and a controller that form measurement images between images on first and second sheets of different lengths, measuring and adjusting image forming conditions based on feedback from sensors, with a higher feedback rate for long sheets to ensure density convergence on a target density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the image forming apparatus continuously forms images on long sheets, then the productivity is improved, but the image density consistency deteriorates due to longer time intervals between density adjustments
Solution Approach 1:
The system performs preliminary density measurement and adjustment actions by forming measurement images between actual images on the image bearing member. This allows density correction to be proactively applied before the next actual image is formed, ensuring consistent density even during continuous long-sheet printing operations.
Solution Approach 2:
The system implements a feedback mechanism where the measurement unit measures the density of measurement images, and the controller adjusts image forming conditions based on the measurement results. This closed-loop feedback ensures that density variations are detected and corrected in real-time during continuous printing, maintaining manufacturing precision while improving productivity.
2Manufacturing precision
If measurement images are formed between every image on long sheets, then the image density consistency is improved, but the device complexity increases
Solution Approach 1:
The system applies local quality by forming measurement images only in specific intervals between actual images, rather than between every single image. The controller determines the frequency of measurement image formation based on the type of sheets being printed (short sheets vs. long sheets), applying different measurement frequencies to different operating conditions to maintain precision without excessive complexity.
Solution Approach 2:
The system performs partial measurement actions by forming measurement images only when necessary (between images on long sheets or according to predetermined intervals), rather than continuously between every image. This partial action approach maintains sufficient density control while avoiding the excessive complexity that would result from measuring between every single image.
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 effectively maintains consistent image density by adjusting image forming conditions with a higher feedback rate for long sheets, preventing density variations and ensuring output images converge on a target density, even during continuous printing.
Implementation Method 1
a sensor configured to measure a measurement image formed on the image bearing member
Data Source
AI summary
In an image forming apparatus, when images are formed on a plurality of sheets, a controller controls an image forming unit to form a measurement image between an image which is to be transferred to a first sheet of the plurality of sheets and an image which is to be transferred to a second sheet of the plurality of sheets, controls a sensor to measure the measurement image, determines a feedback condition based on a length of each of the plurality of sheets in a conveyance direction, and controls an image forming condition based on a result of measurement performed by the sensor and the determined feedback condition, wherein the image which is to be transferred to the second sheet of the plurality of sheets is adjacent to the image which is to be transferred to the first sheet of the plurality of sheets on an image bearing member.