Image Magnification Correction for Duplex Printing Thermal Shifts
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High-speed image forming apparatuses face challenges in maintaining image quality due to thermal influences during duplex printing, leading to magnification differences and image deterioration, particularly with higher resolution images, where methods to adjust magnification introduce global defects like uneven density and moiré patterns.
Innovation Solution
An image forming apparatus and method that include an image-data acquiring unit, resolution converting unit, position determining unit, density determining unit, and correcting unit to add additional pixels based on pixel positions and shifts, scaling the image data by repeatedly determining and correcting positions and densities across sub-scanning and main-scanning lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-speed duplex printing is performed to increase productivity, then the number of prints per minute increases, but thermal influence causes magnification difference and image quality deterioration
Solution Approach 1:
The patent applies preliminary action by calculating and applying different scaling ratios to first and second side images before printing. The system determines a first scaling ratio for the first side image and a second scaling ratio for the second side image based on thermal influence predictions, adjusting the images in advance to compensate for expected magnification differences during high-speed duplex printing operation.
Solution Approach 2:
The patent applies local quality by treating the first and second side images differently with distinct scaling ratios. Instead of using a uniform scaling approach, the system applies localized correction to each side based on its specific thermal conditions, ensuring each image maintains optimal quality despite the thermal influence affecting different sides of the sheet differently.
2Manufacturing precision
If image data is enlarged by adding pixels to adjust magnification, then magnification difference is eliminated, but global image defects like uneven density and moiré patterns appear
Solution Approach 1:
The patent applies parameter changes by adjusting the scaling ratio as a variable parameter for each image side. The system calculates specific scaling ratios (first scaling ratio and second scaling ratio) based on thermal influence conditions and applies these parameters to adjust the magnification of first and second side images respectively, eliminating the need for pixel addition while maintaining image quality.
3Manufacturing precision
If conventional magnification adjustment methods are used to eliminate magnification difference, then magnification consistency is improved, but banding is caused by interference between screen ruling and magnification ratio
Solution Approach 1:
The patent applies parameter changes by using calculated scaling ratios that compensate for thermal-induced magnification differences without introducing conventional magnification adjustment artifacts. The system determines appropriate scaling factors based on thermal conditions, avoiding the screen ruling interference that occurs with traditional pixel addition methods and thereby preventing banding while maintaining magnification consistency.
Data Source
AI summary
An image forming apparatus includes a resolution converting unit, an address generating unit, a density determining unit, and an image path selector. The resolution converting unit converts a resolution of image data into a higher resolution. The address generating unit performs a position determining process of determining a position of an additional pixel on the basis of main-scanning directional positions of pixels composing the converted image data and respective shift amounts of the pixels shifted to a sub-scanning direction. The density determining unit determines a density of the additional pixel on the basis of a density of a pixel located at a position corresponding to the determined position in the image data. The image path selector scales the image data up or down by controlling the address generating unit while adding the additional pixel having the determined density to the determined position.