Image Density Control in Image Forming Apparatus
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Solution Overview
Problem
Existing image forming apparatuses using two-component developers face challenges in maintaining consistent image density and toner concentration, leading to potential background fog and unstable image quality, especially when left unused in humid environments.
Innovation Solution
The apparatus includes a controller that forms detection toner images on an image bearer, adjusts developing potential, and controls toner concentration using a toner supply device to maintain target image density and concentration, suspending printing when toner concentration exceeds thresholds to prevent abrupt rises and maintain image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the image forming apparatus is left unused in humid environments, then the apparatus remains idle, but the toner concentration increases and image density becomes unstable causing background fog
Solution Approach 1:
The controller performs preliminary adjustment of the developing potential before standard image formation starts. This preliminary action compensates for humidity-induced toner concentration changes in advance, preventing background fog and image density instability before they occur during idle periods in humid environments.
Solution Approach 2:
The system uses image density detection to provide feedback to the controller, which then adjusts the developing potential accordingly. This closed-loop feedback mechanism continuously compensates for toner concentration fluctuations caused by humidity, maintaining stable image density and preventing background fog during both operation and idle periods.
2Manufacturing precision
If the developing potential is adjusted to maintain target image density, then image quality improves, but the system complexity increases due to additional control mechanisms
Solution Approach 1:
The system employs an image density detector that provides feedback to the controller, which automatically adjusts the developing potential to maintain target image density. This feedback-based automatic control achieves high precision image density control without requiring complex manual intervention or additional hardware components.
Solution Approach 2:
The system performs self-adjustment of the developing potential based on detected image density values. The controller automatically compensates for deviations from target density by adjusting the developing potential, enabling the system to maintain high precision image quality through self-service without external intervention.
3Manufacturing precision
If the toner concentration is increased to improve image density, then image formation quality improves, but background fog occurs and image quality becomes unstable
Solution Approach 1:
The system dynamically adjusts the developing potential parameter in response to detected image density values and toner concentration changes. By changing the developing potential parameter rather than directly controlling toner concentration, the system achieves desired image density while preventing the harmful effect of background fog that occurs when toner concentration becomes too high.
4Stability of the object's composition
If the developing potential is adjusted frequently to maintain target density, then image density stability improves, but the adjustment timing complexity increases
Solution Approach 1:
The controller performs adjusting operations at predetermined intervals or under specific conditions (such as when image density deviations are detected). This periodic adjustment strategy maintains image density stability while avoiding excessive or unnecessary adjustments, thereby simplifying the timing control logic compared to continuous adjustment mechanisms.
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 solution ensures stable image density and prevents background fog by dynamically adjusting developing potential and toner concentration, effectively addressing the issues of toner concentration fluctuations and humidity-induced degradation.
Implementation Method 1
a toner concentration detector to detect a toner concentration of the developer in the developing device
Implementation Method 2
an image density detector disposed facing a surface of the image bearer to detect an image density of the detection toner image on the image bearer
Implementation Method 3
In the development gap, an electrical field (developing potential) is generated between the developing roller, to which a developing bias is applied, and the photoconductor drum having a latent image potential. Then, the toner in the two-component developer adheres to a latent image on the photoconductor drum due to the electrical field.
Data Source
AI summary
An image forming apparatus includes an image bearer, an image forming device, a toner concentration detector, a toner supply device, an image density detector, and a controller including a memory device. At a predetermined timing before image formation is started, the controller adjusts a developing potential to adjust an image density of a detection toner image on the image bearer and drives the toner supply device or the developing device to adjust a toner concentration in the developing device. After the image formation is started, the controller drives the toner supply device to adjust the toner concentration, and, in a predetermined sheet interval, adjusts the target concentration based on the image density of the detection toner image formed in a non-image area of the image bearer. When the toner concentration is higher than the target concentration plus a threshold, the controller suspends image formation and readjusts the developing potential.