Background Fog Pattern Detection for Charging Bias Control
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Solution Overview
Problem
Conventional image forming apparatuses face challenges in maintaining a constant electric potential on the surface of a photosensitive member due to environmental changes, electrical resistance variations, and surface layer abrasion, leading to issues like background fog and carrier adhesion, which are difficult to accurately identify and prevent.
Innovation Solution
An image forming apparatus that includes a latent image bearing member, a charging unit, a development unit, a toner detector, and a controller, which forms a background fog pattern by gradually changing the background potential and adjusts the charging bias based on detected toner adhesion amounts to prevent background fog and carrier adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a constant charging bias is used, then the charging process is simple, but the background potential changes due to environmental factors and component degradation
Solution Approach 1:
The system performs preliminary measurements of background potential at multiple positions along the photosensitive member before actual imaging. These preliminary actions allow the system to identify potential variations and adjust charging bias accordingly, preventing background fog and carrier adhesion before they occur during normal operation.
Solution Approach 2:
The system continuously monitors background potential at different positions along the photosensitive member and uses this feedback to dynamically adjust the charging bias. By comparing measured potentials and detecting variations, the controller modifies the charging parameters to maintain stable background potential despite environmental changes and component degradation.
2Device complexity
If background potential is not adjusted, then the device complexity is low, but background fog and carrier adhesion occur
Solution Approach 1:
The system divides the photosensitive member surface into multiple measurement positions along its length. By segmenting the potential measurement into discrete positions, the system can identify local variations in background potential and apply targeted adjustments to charging bias for each region, effectively preventing background fog and carrier adhesion without requiring complex continuous adjustment mechanisms.
Solution Approach 2:
The system changes the charging bias parameter based on measured background potential variations at different positions. By adjusting the charging bias parameter dynamically according to actual potential measurements, the system prevents harmful effects like background fog and carrier adhesion while maintaining relatively simple device architecture.
3Device complexity
If toner adhesion amount is not detected, then the measurement system is simple, but the charging bias cannot be precisely controlled
Solution Approach 1:
The system replaces complex mechanical measurement methods with optical detection to measure toner adhesion amount. By using optical sensors to detect toner presence and quantity on the photosensitive member surface, the system achieves precise charging bias control without adding complex mechanical measurement equipment, maintaining simplicity while improving precision.
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 prevents background fog and carrier adhesion by accurately identifying the entry time of each section of the background fog pattern into the detection range, ensuring precise control of the charging bias and maintaining image quality despite environmental and operational changes.
Implementation Method 1
a charging unit (3Y) that charges a surface of the latent image bearing member (2Y)
Implementation Method 2
The controller gradually changes a background potential serving as a potential difference between a background area of the latent image bearing member and a development member of the development unit while causing the latent image bearing member to rotate
Implementation Method 3
The toner detector detects a toner adhesion amount on at least one of the surface of the latent image bearing member and a surface of the transfer member
Data Source
AI summary
An image forming apparatus includes a latent image bearing member, a charging unit, a charging power source, a latent image writing unit, a development unit, a transfer unit, a toner detector, and a controller. The controller causes a background fog pattern to be formed on a surface of the latent image bearing member. In addition to the background fog pattern, the controller causes a latent image to be developed to form a toner image used for position identification on the surface of the latent image bearing member. The controller identifies a time when the toner image used for position identification has entered a detection range of the toner detector based on a change in outputs of the toner detector to determine a time when each of sections of the background fog pattern enters the detection range based on the identified time.