Digital Control for Multi-Head Image Alignment
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Solution Overview
Problem
Existing image forming apparatuses face challenges in achieving high-quality image formation with minimized connecting portion errors, particularly due to mechanical and optical system inaccuracies, which result in visible misalignments and irregularities in image recording.
Innovation Solution
The method involves using a digital control system to adjust the alignment of writing units in a sub-scanning direction, allowing for precise correction of misalignments by varying the shift amount between image parts, thereby reducing errors caused by mechanical, optical, or assembly process fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If independently controllable moving means are provided to each recording head to correct beam spot position, then image connecting portion accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces mechanical moving means with a computational approach. A calculation unit computes correction amounts based on detected beam spot positions, and a control unit applies these corrections to the recording heads. This substitutes complex mechanical independent control systems with a simpler computational control system that achieves the same image alignment accuracy.
Solution Approach 2:
The patent implements a universal control system that manages multiple recording heads through a single calculation unit and control unit. Instead of providing independent moving means for each head, the system uses a shared control architecture that calculates and applies corrections to all heads, reducing overall device complexity while maintaining individual head positioning accuracy.
2Productivity
If multiple image forming apparatuses are used to increase productivity, then output is improved, but connecting portion errors between adjacent writing units worsen
Solution Approach 1:
The patent implements a feedback mechanism where beam spot position detectors monitor the actual positions of recording heads, and this detection information is fed back to the calculation unit. The calculation unit computes correction amounts based on this feedback and adjusts the recording head positions accordingly. This closed-loop feedback system ensures high connecting portion accuracy even when multiple apparatuses work simultaneously to increase productivity.
Solution Approach 2:
The patent creates a virtual model or map of the actual beam spot positions detected by the position detectors. This copied position information is then used by the calculation unit to determine precise correction amounts, allowing the system to compensate for positional deviations and maintain high image quality across multiple writing units.
Data Source
AI summary
An image forming method is performed by an image forming apparatus having a head mounting a plurality of writing units that form an image on a recording medium. The writing units are aligned in a sub-scanning direction perpendicular to a main-scanning direction. A part of the image is formed on the recording medium by the writing units, the part of the image forming a line extending in the main-scanning direction. The step of forming a part of the image is repeated while shifting the writing units in the sub-scanning direction by a predetermined amount of shift. The amount of shift of the wiring units is varied so that an amount of misalignment in a connecting portion between the parts of the image on the recording medium is reduced.