Image Forming Apparatus Screen Selection for Intermediate Gradation
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Solution Overview
Problem
Electrophotographic image forming apparatuses face challenges in maintaining process stability while achieving high resolution, particularly in reproducing intermediate gradation, as the stability degrades with increased resolution, leading to issues like pseudo-contour and poor image reproducibility.
Innovation Solution
An electrophotographic image forming apparatus that selects screens from multiple groups based on gradation values, with specific rules for expanding toner adhesion and non-adhesion regions, and dynamically adjusts these regions to maintain stability and accuracy, using a storage unit, screen selector, and image producing unit to form toner images on media.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the interval between adhesion region and non-adhesion region is shortened to increase resolution, then the resolution is improved, but the process stability is degraded
Solution Approach 1:
The patent divides the screen into multiple types (first screen group with dot patterns, second screen group with line patterns, third screen group with open dot patterns) and selectively applies different screen types to different gradation ranges. This segmentation allows each screen type to operate within its optimal stability range while collectively achieving high resolution across all gradation levels.
Solution Approach 2:
The patent dynamically switches between different screen types based on the gradation value being reproduced. The controller selects appropriate screens from the storage unit depending on whether the gradation is low, medium, or high, allowing the system to adapt the screen configuration to maintain both resolution and stability across different imaging conditions.
2Reliability
If a conventional screen is used for intermediate gradation region to maintain process stability, then the process stability is maintained, but the resolution is limited
Solution Approach 1:
The patent applies different screen characteristics to different spatial regions of the image based on their gradation requirements. Character regions use one screen type while intermediate gradation regions use another, allowing each region to receive the optimal screen configuration for its specific needs, thereby achieving both stability and high resolution where required.
Solution Approach 2:
The patent creates a composite screen system combining multiple screen types (dot patterns, line patterns, open dot patterns) that work together to reproduce the full range of gradation values. This composite approach leverages the strengths of each screen type to achieve both high resolution and stable process across the entire dynamic range.
3Manufacturing precision
If multiple screen groups are stored and selectively used based on gradation values, then the intermediate gradation reproducibility is enhanced, but the device complexity increases
Solution Approach 1:
The patent pre-stores multiple screen configurations in the storage unit before actual image formation. The controller simply needs to retrieve the appropriate pre-configured screen based on the gradation value, avoiding the need to calculate or generate screens in real-time, thus reducing computational complexity while maintaining high reproducibility.
Solution Approach 2:
The patent uses multiple copies of screen patterns (dot, line, open dot) that can be selectively retrieved and applied. Instead of creating unique screens for each gradation level, the system reuses and combines existing screen patterns, reducing the overall complexity of screen management while achieving diverse gradation reproduction.
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 effectively stabilizes the process while achieving higher resolution for intermediate gradation, reducing pseudo-contour issues and improving image reproducibility by selectively switching between dot, line, and open dot screens based on gradation values, ensuring consistent toner adhesion and non-adhesion regions.
Implementation Method 1
a storage unit for storing a first screen group and a second screen group
Implementation Method 2
the screen selector relocates a first portion and a second portion such that the first portion and the second portion are joined by the second region
Implementation Method 3
an image producing unit for performing image formation using the selected screen
Data Source
AI summary
A first screen group and a second screen group are stored in an image forming apparatus. In the first screen group, the first region expands with increasing gradation value based on a first rule. In the second screen group, the first region expands with increasing gradation value based on an independent second rule different from the first rule. A screen selector relocates a first portion and a second portion such that the first portion and the second portion are joined by a second region that is not a toner adhesion control target, when the first portion and the second portion are adjacent as a result of the selection of the screen in each unit region of the input image. The first portion includes the screen included in the first screen group, and the second portion includes the screen included in the second screen group.