Image Forming Apparatus Tone Reproducibility Control
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Solution Overview
Problem
Existing image forming apparatuses face challenges in stabilizing tone reproducibility and reducing noise or pseudo contours, particularly in highlight regions, due to variations in environment and usage situations, despite efforts like gamma correction and frequency modulation.
Innovation Solution
An image forming apparatus and method that adjusts the dot size of AM screens based on environment variables and usage situations by forming a test pattern, detecting its density, and determining the smallest dot size for halftone representation in highlight regions using a dither pattern.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If frequency modulation is used to perform tone representation by enlarging dot size in highlight region, then tone reproducibility is improved, but image defects such as noise and pseudo contours occur due to change of state of the machine
Solution Approach 1:
The patent dynamically adjusts the smallest dot size of the AM screen based on the actual area ratio of halftone dots in the highlight region, which is determined through test pattern formation and density detection. This dynamic adjustment allows the system to adapt to changes in machine state and environmental conditions, resolving the contradiction between maintaining tone reproducibility and preventing image defects.
Solution Approach 2:
The patent implements a feedback mechanism where the density of the test pattern is detected and used to calculate the actual area ratio of halftone dots. This feedback information is then used to adjust the smallest dot size of the AM screen, creating a closed-loop control system that stabilizes tone reproducibility while suppressing image defects.
2Device complexity
If AM screen dot size is fixed, then device complexity is reduced, but tone reproducibility deteriorates under varying environment and usage situations
Solution Approach 1:
The patent makes the smallest dot size of the AM screen dynamically adjustable based on actual measurement results from test patterns. This dynamic capability allows the system to maintain simple device architecture while achieving adaptive tone reproduction that responds to environmental and usage condition variations.
3Manufacturing precision
If gamma correction is applied to improve tone reproducibility, then tone range is expanded, but noise and pseudo contours become more noticeable in highlight regions
Solution Approach 1:
The patent changes the parameter of smallest dot size in the AM screen configuration based on measured area ratios from test patterns. This parameter adjustment optimizes the balance between tone reproducibility and image quality, allowing gamma correction to be applied effectively while suppressing the visibility of noise and pseudo contours in highlight regions.
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
This approach stabilizes tone reproducibility and suppresses noise and pseudo contours by optimally determining the dot size for halftone representation, ensuring high-quality image output across varying conditions.
Implementation Method 1
the photosensitive member that is uniformly charged is exposed by the laser beam in accordance with the image signal, the electric potential of the exposed photoreceptor surface attenuates, and an electrostatic latent image is formed at the exposed portion
Implementation Method 2
When a development bias is applied between the photosensitive member where the electrostatic latent image is formed and a carrier of developer, the electrostatic latent image is developed by toner adhering thereto in accordance with a potential difference between the potential after the exposure and a developing potential
Data Source
AI summary
The present image forming apparatus, upon accepting, in accordance with a user input, an instruction for execution of processing for adjusting an image forming condition, forms a predetermined test pattern on a sheet, and detects the density of the predetermined test pattern. Furthermore, the image forming apparatus obtains an area ratio of halftone dots in a highlight region of a formed image from the detected density, and, based on the area ratio of halftone dots, decides a smallest dot size for a screen that represents a halftone of the highlight region by a dither pattern.