Image Forming Apparatus Registration Correction via Resolution Segmentation
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Solution Overview
Problem
Digital printers employing the electrophotographic process face challenges in maintaining accurate registration between the front and back sides during two-sided printing due to sheet shrinkage during thermal fixing, leading to misregistration, and existing solutions either fail to reduce data transfer volume or are limited by interference with dithering during high-resolution image processing.
Innovation Solution
An image forming apparatus that performs precise position correction of images before gradation processing, using a light source, image processing unit, modulation signal generation, and correction value identification to convert image data to higher resolutions without increasing the amount of transferred data, allowing for high-resolution image processing while maintaining accurate registration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high resolution image processing (2400 dpi or 4800 dpi) is performed to improve registration accuracy and image quality, then manufacturing precision and reliability are improved, but the amount of data transferred to the light source driving circuit increases significantly, reducing productivity
Solution Approach 1:
The image data processing is segmented into two stages: first, deformation processing (rotation, scaling, shifting) is performed on the original resolution image data; second, the processed data is converted to high resolution (2400 dpi or 4800 dpi) only in the modulation signal generation unit. This segmentation allows registration correction without requiring the entire system to handle high resolution data, thus maintaining productivity while achieving accurate registration.
Solution Approach 2:
The patent transitions from processing high resolution image data directly to processing lower resolution data that is then converted to high resolution in a different stage (modulation signal generation). This dimensional change in the processing pipeline allows the system to achieve high resolution output without the burden of handling large high resolution data throughout the entire processing chain, resolving the contradiction between registration accuracy and productivity.
2Manufacturing precision
If position correction is performed after gradation processing, then the image processing pipeline is maintained, but correction is limited by interference with dithering and cannot achieve large dynamic range correction
Solution Approach 1:
The patent performs deformation processing (rotation, scaling, shifting) before gradation processing and dithering. By applying position correction preliminarily to the original image data, the system avoids interference with subsequent gradation and dithering processes, enabling large dynamic range correction while maintaining the standard image processing pipeline.
3Reliability
If multi-bit data with high resolution (2400 dpi or 4800 dpi) is processed to improve flexibility and reproducibility of small letters and lines, then image quality is improved, but the amount of data transferred to the light source driving circuit increases, limiting production rate
Solution Approach 1:
The patent segments the image processing into deformation processing at original resolution followed by high resolution conversion only in the modulation signal generation unit. This ensures small letters and lines are reproduced accurately through high resolution modulation signals while avoiding the productivity loss of processing multi-bit high resolution data through the entire system.
Solution Approach 2:
The patent changes the resolution parameter dynamically: deformation processing operates on original resolution data, while the modulation signal generation unit converts to high resolution (2400 dpi or 4800 dpi) only when needed for final output. This parameter change strategy maintains reproducibility of fine details while optimizing production rate by minimizing high resolution data handling.
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
Enables precise registration between the front and back sides in two-sided printing without increasing data transfer volume, enhancing productivity and image quality by performing position correction before gradation processing and converting image data to higher resolutions for accurate registration.
Implementation Method 1
a photoconductor drum having a photoconductive scan surface, a light source which emits a laser beam, a polygon mirror for deflecting the laser beam emitted from the light source, and a scanning optical system for introducing the laser beam deflected by the polygon mirror to the surface of the photoconductor drum (scan surface). The digital printer employing the electrophotographic process modulates the light flux emitted from the light source based on image data and irradiate the scan surface with the resulting light flux so as to scan the scan surface to produce an electrostatic latent image corresponding to the image data on the photoconductor drum.
Data Source
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AI summary
An image forming apparatus forms an image by optical scanning. The image forming apparatus includes: a light source; an image processing unit that processes image data; a modulation signal generation unit that generates a light source modulation signal; a light source drive unit that drives the light source based on the light source modulation signal; and a correction value identifying unit that identifies a correction value for correcting a registration error of an image to be formed. The image processing unit performs first image processing of image data with first resolution based on a correction value identified by the correction value identifying unit, the first image processing including deformation processing and gradation processing of the image data. The modulation signal generation unit converts image data processed in the image processing unit into image data with resolution higher than the first resolution and performs second image processing.