Image Forming Apparatus Tone Correction for Mirror Tangle Errors
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Solution Overview
Problem
Existing image forming apparatuses face challenges in maintaining stable image quality due to tone changes caused by environmental fluctuations and optical face tangle errors, leading to uneven image density and banding issues.
Innovation Solution
An image forming apparatus is designed with a tone correction table, dither processing, and a correction unit that adjusts for positional deviations caused by mirror face tangle errors, using a light source with multiple emission points and a photosensitive member to form scanning lines, along with an extraction unit to determine tone changes and adjust accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If exposure amount is controlled to correct uneven image density caused by scanning line interval variations, then banding is reduced, but tone characteristics change due to environmental fluctuations and optical face tangle errors
Solution Approach 1:
The system performs preliminary tone correction by storing correction values in a tone correction table before image formation. The extraction unit pre-identifies tone changes by analyzing patch images, and the correction unit pre-calculates appropriate correction amounts based on optical face tangle errors. This preliminary action ensures that when actual image formation occurs, the correct exposure amounts are already determined, preventing tone characteristic instability caused by environmental fluctuations.
Solution Approach 2:
The system establishes a feedback loop where patch images are formed and their density is measured by a density measurement unit. The extraction unit compares measured density values with target values to identify tone changes. This feedback information is then used by the correction unit to adjust exposure amounts, creating a closed-loop control system that maintains tone characteristic stability despite environmental variations.
2Adaptability or versatility
If a line screen is used for halftone processing, then intermediate tones are expressed, but moire appears strongly due to regular extension of screen lines
Solution Approach 1:
The system applies different dither patterns to different regions or types of images based on their specific characteristics. By analyzing image features, the system selects appropriate dither patterns (such as dot screens, line screens, or error diffusion patterns) for different areas, allowing halftone expression while minimizing moire in regions where it would be problematic.
Solution Approach 2:
The system changes the parameters of the dither pattern based on image characteristics and viewing conditions. By adjusting parameters such as screen angle, screen frequency, and dot shape, the system optimizes halftone expression while reducing moire. The correction unit also applies parameter changes to exposure amounts based on identified tone variations, further reducing visual artifacts.
3Manufacturing precision
If scanning line intervals are kept equal to avoid banding, then image density becomes uniform, but mechanical fluctuations in photosensitive member speed and rotary polygon mirror rotation cause interval variations
Solution Approach 1:
The system replaces mechanical precision requirements with optical and computational solutions. Instead of relying on perfectly stable mechanical rotation of the photosensitive member and rotary polygon mirror, the system uses a light scanning device with multiple light emission points and applies computational correction through the tone correction table. The extraction unit detects interval variations and the correction unit compensates for them, substituting mechanical stability requirements with optical flexibility and information processing.
Solution Approach 2:
The system changes exposure parameters dynamically based on detected scanning line interval variations. When intervals become unequal due to mechanical fluctuations, the correction unit adjusts exposure amounts for affected scanning lines to compensate for the uneven spacing. This parameter change approach maintains image density uniformity despite mechanical speed variations.
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 enables the formation of images with stable quality by accurately correcting for tone changes and environmental fluctuations, effectively addressing uneven image density and banding issues.
Implementation Method 1
a light source configured to emit light beams; a deflection unit configured to deflect the light beams emitted from the light source
Implementation Method 2
a photosensitive member configured to rotate in the first direction so that a latent image is formed on the photosensitive member by the light beams emitted from the light source
Data Source
AI summary
An image forming apparatus including: a first processing unit configured to subject input image data to tone correction with use of a tone correction table; a second processing unit configured to subject the image data to dither processing; a correction unit configured to correct the image data with use of a correction amount based on positional deviation of scanning lines caused by a mirror face tangle error; a deflection unit configured to deflect light beams emitted from the light source with a mirror face to form the scanning lines; an extraction unit configured to extract a feature amount of the tone correction table; and an adjustment unit configured to adjust a change in tone characteristics in a case where the feature amount extracted by the extraction unit exceeds a predetermined range.