Image Density Correction via Dispersed Measurement Regions
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Solution Overview
Problem
Existing electrophotographic image forming technologies face challenges in maintaining consistent image density due to environmental and operational factors, leading to variations in color balance and reduced image quality, particularly due to periodic density unevenness in rotating members like photosensitive drums.
Innovation Solution
An image forming apparatus that includes a conversion unit for converting image data based on specific conditions, an image bearing member that rotates, an image forming unit that forms measurement images of varying densities, and a controller that detects these images to generate correction conditions, while dispersing the measurement images to account for periodic unevenness along the rotation direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If averaging methods are used to suppress density unevenness, then the influence of periodic density unevenness is reduced, but the number of patch images required increases and characteristic information may be lost
Solution Approach 1:
The patent divides the image bearing member into multiple measurement regions along its rotation direction. By segmenting the continuous measurement into discrete regional measurements, the system can suppress periodic density unevenness without requiring a complete average of all possible patch images, thus reducing the number of required measurements while maintaining reliability.
Solution Approach 2:
The patent applies different measurement strategies to different regions of the image bearing member. Instead of uniformly averaging all regions, it selectively measures and corrects based on the specific characteristics of each region, preserving local characteristic information while suppressing periodic unevenness.
2Reliability
If averaging methods are used to suppress density unevenness, then the influence of periodic density unevenness is reduced, but characteristic information relating to density unevenness may be uniformly averaged and lost
Solution Approach 1:
By segmenting the measurement into discrete regional measurements rather than a continuous average, the system preserves discrete characteristic information from each region while still achieving overall density consistency through selective correction based on regional measurements.
Solution Approach 2:
The patent performs preliminary identification and classification of measurement regions before correction. This preliminary action allows the system to understand the distribution of characteristic information and apply corrections that preserve important characteristics while suppressing periodic unevenness.
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 stabilizes image quality by reducing the influence of density unevenness, preventing the need for increased patch images and preserving original characteristic information, thus ensuring consistent grayscale control and maintaining image quality with fewer gradation levels.
Implementation Method 1
a conversion unit configured to convert image data based on a conversion condition
Implementation Method 2
an image forming unit configured to form an image on the image bearing member based on the image data converted by the conversion unit
Implementation Method 3
an exposure amount, a developing bias, and a γ correction table. The exposure amount refers to an amount of laser light to be radiated to the image bearing member by an exposing device
Implementation Method 4
a sensor configured to detect a measurement image formed on the image bearing member
Implementation Method 5
an image bearing member configured to rotate in a predetermined direction
Data Source
AI summary
An image forming apparatus configured to form an image on a sheet includes an image bearing member configured to rotate in a predetermined direction, and an image forming unit configured to form an image on the image bearing member based on image data converted based on a conversion condition. A controller of the image forming apparatus controls the image forming unit to form a plurality of measurement images different in density along the predetermined direction of the image bearing member, detects the plurality of measurement images, and generates the conversion condition based on detection results of the plurality of measurement images. The controller controls the image forming unit to form the plurality of measurement images in a dispersed manner in terms of positions of the plurality of measurement images on the image bearing member in accordance with periodic unevenness that occurs in the measurement images.