Image Forming Apparatus Speed Control for Magnification Stability
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Solution Overview
Problem
In image forming apparatuses using a secondary transfer system, adjusting the speed difference between the intermediate transfer member and the sheet conveyance speed to improve image quality leads to image deformation and magnification changes in the sub-scanning direction, requiring complex adjustments and downtime for color registration to maintain image stability.
Innovation Solution
An image forming apparatus with a controller that measures and adjusts the image length in the conveyance direction by controlling the rotational speed of the transfer member, forming a measurement image to determine adjustment conditions, allowing for precise control of image formation without relying on speed differences, thereby stabilizing image magnification in the sub-scanning direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the speed difference between the intermediate transfer member and the sheet conveyance speed is adjusted to improve image quality, then image quality is improved, but image deformation and magnification changes occur in the sub-scanning direction
Solution Approach 1:
The patent changes the rotational speed parameter of the intermediate transfer member to improve image quality by reducing graininess and enhancing transfer performance. By adjusting the speed difference between the intermediate transfer member and sheet conveyance, the system optimizes image formation quality while managing the resulting magnification changes through controlled parameter variation.
2Shape
If the rotational speed of the intermediate transfer member is adjusted to change image magnification, then image magnification is controlled, but color misregistration occurs
Solution Approach 1:
The patent implements a feedback control system that detects color misregistration caused by speed adjustments and automatically corrects it. By monitoring the registration accuracy and adjusting the rotational speeds of the intermediate transfer member and secondary transfer roller in response to detected deviations, the system maintains both magnification control and color registration precision.
3Stability of the object's composition
If complex adjustments are performed to maintain image stability, then image stability is improved, but processing time increases
Solution Approach 1:
The patent performs preliminary adjustments of the rotational speeds of the intermediate transfer member and secondary transfer roller based on pre-stored optimal speed combinations for different sheet types. By preparing and storing optimal parameter sets in advance, the system can quickly switch between configurations without performing complex real-time adjustments, thereby maintaining image stability while minimizing processing time.
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 solution enables stable image formation with improved quality by eliminating the need for complex adjustments and downtime, ensuring consistent image magnification and reduced downtime through precise control of the image forming process.
Implementation Method 1
Secondary transfer is performed at a nip portion, which includes a drive roller around which the intermediate transfer member is looped and a secondary transfer roller, by nipping the intermediate transfer member and the sheet between the drive roller and the secondary transfer roller
Data Source
AI summary
Provided is an image forming apparatus having high usability and securing both image quality and productivity. The image forming apparatus changes a rotational speed of a secondary transfer member depending on a basis weight of a sheet. The image forming apparatus performs digital sub-scanning scaling of correcting image data and polygon sub-scanning scaling of controlling a scanning speed during image formation so as to cancel out image deformation caused by change in rotational speed of the secondary transfer member. When giving priority to image quality, the image forming apparatus performs processing of the digital sub-scanning scaling and the polygon sub-scanning scaling, and when giving priority to productivity, the image forming apparatus performs only processing of digital sub-scanning scaling.