Image Magnification Correction via Conveyance Speed Feedback
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Solution Overview
Problem
Image forming apparatuses face challenges in accurately correcting image magnification errors in the sub-scanning direction due to variations in toner adhesion amount, leading to inconsistencies in image size on the recording medium.
Innovation Solution
The apparatus includes a rotatable image bearer, a transfer rotator, and a detector, with circuitry that adjusts the conveyance speed by controlling the relative linear velocity between the image bearer and transfer rotator, using correction values based on detected length information to correct image magnification errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the image forming apparatus uses a fixed conveyance speed for the recording medium, then the device operation is simple, but the image magnification accuracy deteriorates due to variations in toner adhesion amount
Solution Approach 1:
The apparatus employs a feedback mechanism where the detection unit measures the actual length of the transferred image, and the control unit adjusts the conveyance speed based on the difference between the detected length and the target length. This closed-loop control ensures accurate image magnification by continuously correcting conveyance speed variations caused by toner adhesion amount changes.
Solution Approach 2:
The system transitions from a static fixed conveyance speed to a dynamic adjustable conveyance speed. The conveyance speed is no longer constant but is dynamically modified in real-time based on detected image length variations, allowing the system to adapt to changing conditions and maintain precision.
2Manufacturing precision
If the apparatus adjusts conveyance speed to correct image magnification, then image size consistency improves, but the control system complexity increases
Solution Approach 1:
The control unit receives length information from the detection unit and automatically adjusts the conveyance speed without manual intervention. This automated feedback loop maintains image size consistency by compensating for toner adhesion variations, reducing the need for complex manual calibration procedures.
Solution Approach 2:
The system performs self-correction of image magnification errors through automated detection and adjustment. The detection unit and control unit work together to automatically compensate for variations in toner adhesion amount, eliminating the need for external calibration or manual adjustment mechanisms.
3Measurement precision
If the apparatus uses a simple detection method for image length, then the device complexity remains low, but the measurement precision of image length deteriorates
Solution Approach 1:
The detection unit acts as an intermediary between the image transfer process and the control system. It provides accurate length measurements by detecting the actual image dimensions on the recording medium, enabling the control unit to make precise adjustments to conveyance speed without requiring complex direct measurement mechanisms.
Data Source
AI summary
An image forming apparatus includes a rotatable image bearer, a transfer rotator, a detector, and circuitry. The image bearer bears an image. The transfer rotator transfers the image from the image bearer onto a recording medium sandwiched and conveyed between the image bearer and the transfer rotator. The detector detects length information indicating a length, in a direction of conveyance of the recording medium, of the image on the recording medium. The circuitry corrects a correction value, based on the length information detected by the detector and a target value of the length information, to correct an image magnification, in the direction of conveyance of the recording medium, of the image to be formed on the recording medium. The circuitry controls an image forming operation of forming the image on the recording medium with the correction value.