Bitmap Data Shifting for Laser Scanning Line Bending Correction
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Solution Overview
Problem
In spot-multiplexing technology, the thickness of fine lines varies due to differences in electrical potential levels generated during laser scanning, especially for lines with the same width, leading to significant thickness differences, particularly in thin lines.
Innovation Solution
An image processing system that shifts bitmap data in the sub-scanning direction to correct bending of the laser scanning line, converting line drawing commands and generating multi-value bitmap data to maintain consistent line thickness, using a line command conversion unit, generation unit, correction unit, resolution conversion unit, and output unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If spot-multiplexing technology is used to generate dots in intermediate electrical potential levels to achieve high resolution, then image quality with resolution higher than the printing apparatus is obtained, but line thickness varies significantly due to different electrical potential levels at different phases
Solution Approach 1:
The patent applies preliminary action by performing laser bending correction on the bitmap data before generating the multi-value bitmap through spot-multiplexing. The correction data is calculated in advance based on the scanning position, and the bitmap pixels are shifted accordingly before the optical drawing process, preventing line thickness variation from occurring in the first place
Solution Approach 2:
The patent changes the parameter of pixel position in the bitmap data based on the scanning phase. By dynamically adjusting the pixel shift amount according to the phase information, the system compensates for the electrical potential level variations that would otherwise cause line thickness inconsistency, while maintaining the high resolution benefit of spot-multiplexing
2Shape
If laser bending correction is performed by changing phase in sub-scanning direction, then bending of laser scanning line is corrected, but line thickness varies when using intermediate electrical potential levels
Solution Approach 1:
The patent applies local quality by making the pixel shift amount position-dependent. Different regions of the bitmap are shifted by different amounts based on their local phase information. This allows the laser scanning line to be corrected locally at each position while maintaining consistent line thickness, rather than applying a uniform correction that would cause thickness variation
3Shape
If bitmap data is shifted in sub-scanning direction to correct laser bending, then laser scanning line bending is canceled, but additional processing steps are required
Solution Approach 1:
The patent merges the laser bending correction function with the existing spot-multiplexing processing pipeline. The pixel shifting operation is integrated into the bitmap generation process that already exists for spot-multiplexing, rather than adding a completely separate correction system. This reduces overall system complexity by combining functions
Data Source
AI summary
An image processing system performs correction of shifting bitmap data in a sub-scanning direction so as to cancel bending of an electro-photographic laser scanning line. A line command conversion unit converts a first line drawing command defining a line width as an even-number pixel width less than a predetermined even-number pixel width into a second line drawing command defining a line width as the predetermined even-number pixel width, and converts a third line drawing command defining a line width as an odd-number pixel width less than the predetermined even-number pixel width into the second line drawing command. A generation unit generates binary bitmap data with first resolution on a basis of drawing data including the second line drawing command. A correction unit performs the correction with respect to the generated binary bitmap data. A resolution conversion unit converts the binary bitmap data.