Image Forming Apparatus Skew Correction via Segmented Dithering
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Solution Overview
Problem
Conventional image forming apparatuses face challenges in preventing streaks during the density correction process, leading to precision issues in image formation due to coincident application positions of the dither matrix and recording chips, which results in deteriorated density correction precision.
Innovation Solution
An image forming apparatus with a detecting unit to measure skew, a resolution adjusting unit to increase the resolution of the density correction image, and a correction unit that shifts image data in the sub-scanning direction based on the detected skew, effectively preventing streaks by dividing the image into sections in the main-scanning direction and adjusting the dithering process accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If skew correction is performed on image data subjected to dithering process by using dither matrix, then skew correction is achieved, but streaks are generated due to changes in shape of dither matrix pattern at shifted positions
Solution Approach 1:
The image data is divided into multiple sections in the main-scanning direction, and skew correction is performed separately for each section by shifting image data in the sub-scanning direction. This segmentation prevents the dither matrix pattern from undergoing shape changes that cause streaks, while still achieving effective skew correction for the entire image.
2Manufacturing precision
If dithering process is performed on multitone image data, then binarization is achieved, but streaks are generated when application position of dither matrix coincides with boundary position between recording chips
Solution Approach 1:
The density correction image is divided into multiple sections in the main-scanning direction, and skew correction is applied to each section independently. This ensures that the dither matrix application positions do not coincide with recording chip boundaries, preventing streak generation while maintaining high density correction precision.
3Manufacturing precision
If image data is shifted in sub-scanning direction for skew correction, then skew is corrected, but resolution of density correction image deteriorates due to streaks
Solution Approach 1:
By dividing the image into sections and performing skew correction on each section separately, the patent maintains high resolution in the density correction image. The segmented approach prevents streak formation that would otherwise degrade image quality, thereby preserving measurement precision for density correction.
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
The solution enhances precision in density correction by preventing streaks and improving the resolution of the density correction image, thereby maintaining high-quality image formation.
Implementation Method 1
an exposing unit including a plurality of light emitting chips arranged in a main-scanning direction, each of the light emitting chips including a plurality of light emitting elements arranged in the main-scanning direction
Implementation Method 2
a developing unit configured to develop an electrostatic latent image formed on the photosensitive element by the exposing unit to form a toner image
Implementation Method 3
a transfer unit configured to transfer the toner image to a medium to form an image on the medium
Data Source
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AI summary
An image forming apparatus (10) includes an exposing unit (20) including light emitting chips (44) arranged in a main-scanning direction; a developing unit (26) configured to develop an electrostatic latent image formed on a photosensitive element (22) to form a toner image; a transfer unit (28) configured to transfer the toner image to a medium (34); a detecting unit (50) configured to detect an amount of skew in an array direction of each light emitting chip (44); an adjusting unit (68) configured to generate a density correction image to be formed on the medium (34) through dithering, the density correction image having a higher resolution than that of a printing image and having the resolution increased with an increase in the amount of skew; and a correction unit (61) configured to perform skew correction on the density correction image on the basis of the amount of skew.