Dual Controller Image Density Correction for Solid and Halftone Patterns
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Solution Overview
Problem
Existing image forming apparatuses struggle to completely reduce density irregularity across multiple types of images, particularly between solid and halftone images, due to limitations in measuring and correcting periodic density fluctuations, leading to inaccurate identification of irregularity sources and ineffective correction.
Innovation Solution
The apparatus employs a dual controller system to form and detect first and second image patterns on an image bearer, with each controller determining specific image formation conditions based on density detection results to control toner image formation, synchronizing with rotation position and environmental detectors to adjust charging, exposing, and developing conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single type of image data (e.g., solid image) is used to measure periodic variation data for controlling image formation conditions, then density irregularity of solid images can be reduced, but density irregularity of halftone images cannot be reduced and becomes worse
Solution Approach 1:
The invention segments the correction process by creating separate correction data sets for different image types (solid image correction data and halftone image correction data). The system measures periodic variation data using both solid image data and halftone image data separately, then selects and applies the appropriate correction data based on the actual image type being formed. This segmentation allows each correction data set to be optimized for its specific image type, resolving the contradiction between reducing density irregularity for solid images and maintaining adaptability for halftone images.
2Manufacturing precision
If development potential is changed by controlling developing bias to correct solid image density, then solid image density irregularity is reduced, but halftone image density fluctuates unexpectedly due to background potential changes
Solution Approach 1:
The invention implements dynamic control by switching between different correction strategies based on image type. For solid images, the system dynamically adjusts development potential through developing bias control. For halftone images, it dynamically switches to charging condition control instead. This dynamic adaptation resolves the contradiction by applying the appropriate control method for each image type, maintaining both solid image density uniformity and halftone image density stability.
Solution Approach 2:
The invention changes the controlled parameter based on image type: for solid images, it changes development potential (developing bias), while for halftone images, it changes charging conditions instead. This parameter substitution avoids the side effect of background potential fluctuation affecting halftone images, while still achieving density irregularity reduction for solid images through the alternative parameter control.
3Adaptability or versatility
If frequency detection is performed for both solid and halftone images to identify irregularity sources, then comprehensive coverage is achieved, but accurate identification becomes difficult when similar frequency properties are detected despite different irregularity sources
Solution Approach 1:
The invention segments the measurement and identification process by performing frequency detection separately for solid images and halftone images, then identifying irregularity sources independently for each image type. This segmentation prevents confusion when similar frequency properties are detected, as each identification process is tailored to the specific characteristics of its image type, thereby maintaining both comprehensive coverage and accurate identification.
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 effectively reduces density irregularity in both solid and halftone images by accurately identifying and correcting irregularities, ensuring consistent image quality across varying densities.
Implementation Method 1
a charger (3Y) to charge a surface of the image bearer with charge
Implementation Method 2
an optical writing device (4Y) to expose the surface with charge thereby forming a latent image
Implementation Method 3
a developing device (5Y) to visualize the latent image
Data Source
AI summary
In an image forming apparatus, a first controller forms a first image pattern on an image bearer and determines a first image formation condition based on a detection result of density of a toner image. The first controller then controls a toner image forming device based on the first image formation condition. A second controller forms a second image pattern different from the first image pattern on an image bearer and determines a second image formation condition based on a detection result of density of a toner image. The second controller then controls a toner image forming device based on the second image formation condition.