Exposure Corrector for Image Density Variation in Photoconductor Drums
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Solution Overview
Problem
Electrophotographic image forming apparatuses face variations in image density due to irregularities in the photoconductor drum's shape and rotation, leading to cyclical variations in image quality, which existing correction methods fail to address effectively without disrupting print operations.
Innovation Solution
An image forming apparatus incorporating a photoconductor, optical scanner, developing device, density detector, and exposure corrector that adjusts the optical scanner's output based on real-time density variations, allowing for exposure correction during non-printing periods to maintain image quality and productivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If exposure correction is performed during printing operations, then image density variation is reduced, but print productivity decreases due to operational disruptions
Solution Approach 1:
The system performs exposure correction in advance during non-printing periods by storing correction data in a memory unit. The correction values are calculated and prepared before actual printing operations begin, allowing the printing process to proceed without interruption while still applying the corrective measures.
Solution Approach 2:
The correction process is separated into distinct phases: correction data generation during non-printing periods and correction application during printing operations. This segmentation allows the two functions to occur independently without interfering with each other, maintaining both image quality and productivity.
2Manufacturing precision
If real-time density detection and correction is implemented, then image quality improves, but system complexity increases
Solution Approach 1:
A memory unit is introduced as an intermediary component to store correction data. This intermediary allows the system to decouple the correction calculation process from the printing process, simplifying the real-time operation by pre-computing and storing correction values that are then applied during printing without requiring complex real-time processing.
3Measurement precision
If exposure correction data is updated frequently, then image density accuracy improves, but processing time increases
Solution Approach 1:
Correction data is generated and stored in advance during non-printing periods rather than being calculated in real-time during printing. This preliminary preparation allows for accurate density measurement and correction calculation without causing time loss during actual printing operations, as the correction values are already computed and stored in memory.
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 reduces density variations in the sub-scanning direction, enhancing image quality while minimizing disruptions to print operations by updating exposure correction data independently of printing cycles.
Implementation Method 1
An optical writer irradiates the surface of the photoconductor thus charged with a light beam to form an electrostatic latent image on the surface of the photoconductor according to the image data
Implementation Method 2
A developing device supplies toner to the electrostatic latent image thus formed so that the toner adheres to the photoconductor by static electricity
Data Source
AI summary
An image forming apparatus includes a photoconductor, an optical scanner, a developing device, a density detector, and an exposure corrector. The photoconductor is rotatable in a direction of rotation. The optical scanner includes a light source, and drives the light source to form a latent image on a surface of the photoconductor. The developing device develops the latent image to form an image. The density detector detects variation in density of the image in the direction of rotation of the photoconductor. The exposure corrector generates exposure correction data for the optical scanner to reduce the variation in density. The exposure corrector adjusts output of the optical scanner according to the exposure correction data at a time different from a time when the exposure corrector updates the exposure correction data.