Image Forming Apparatus Toner Density Control via Dynamic Patch Detection
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Solution Overview
Problem
Conventional image forming apparatuses using two-component developers face challenges in maintaining stable toner density due to changes in the properties of the magnetic carrier and environment, leading to unpredictable toner replenishment and potential impairment of image stability.
Innovation Solution
An image forming apparatus with a control unit that adjusts the frequency of patch image formation to reduce unnecessary toner replenishment, setting target toner density within upper and lower limits and varying the interval for patch detection ATR based on detected image density, thereby optimizing toner replenishment and maintaining image stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If patch detection ATR is carried out frequently to maintain accurate toner density control, then image density stability is improved, but productivity deteriorates due to increased frequency of patch image formation and toner replenishment operations
Solution Approach 1:
The patent applies dynamics by making the patch detection ATR interval variable rather than fixed. The control unit dynamically adjusts the interval between patch detection ATR operations based on the stability of the target value determined by developer density detection ATR. When the target value is stable, the interval is extended; when unstable, the interval is shortened. This dynamic adjustment optimizes both image density stability and productivity by performing patch detection ATR only when necessary.
Solution Approach 2:
The patent uses feedback by continuously monitoring the target value from developer density detection ATR and using this information to control the frequency of patch detection ATR. The control unit determines whether the target value is stable or unstable and adjusts the patch detection ATR interval accordingly. This feedback mechanism ensures that patch detection ATR is performed frequently enough to maintain image density stability while minimizing unnecessary operations that would reduce productivity.
2Stability of the object's composition
If toner replenishment is performed continuously to maintain toner density, then toner density constancy is improved, but toner waste increases due to unnecessary replenishment operations
Solution Approach 1:
The patent applies periodic action by replacing continuous toner replenishment with interval-based replenishment operations. Instead of continuously monitoring and replenishing toner, the system performs developer density detection ATR periodically to determine the target value, and only performs patch detection ATR and toner replenishment when the target value indicates instability or when the interval expires. This periodic approach maintains toner density constancy while reducing unnecessary replenishment operations and toner waste.
Solution Approach 2:
The patent uses self-service by enabling the system to automatically determine when toner replenishment is necessary through developer density detection ATR and target value stability analysis. The control unit autonomously decides whether to perform patch detection ATR and initiate toner replenishment based on the monitored target value, eliminating the need for continuous external intervention or conservative over-replenishment strategies.
3Measurement precision
If developer density detection ATR is used to control toner density, then toner density control is improved, but image density stability deteriorates when carrier properties change or environment varies
Solution Approach 1:
The patent uses an intermediary approach by introducing the target value as an intermediate parameter between developer density detection ATR and patch detection ATR. The developer density detection ATR determines the target value, which then serves as the basis for controlling patch detection ATR frequency and toner replenishment. This intermediary target value allows the system to translate developer density measurements into actionable control decisions that maintain image density stability even when carrier properties or environmental conditions change.
Solution Approach 2:
The patent replaces direct mechanical/physical monitoring of image density with an electronic control system that uses developer density detection ATR to determine a target value. Instead of relying solely on physical patch detection ATR to maintain image density, the system substitutes electronic monitoring and calculation of the target value from developer density measurements, which then controls the timing and execution of patch detection ATR and toner replenishment operations.
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 reduces the frequency of patch image formation, minimizing wasteful toner replenishment and maintaining stable image density, thus enhancing the stability and productivity of the image forming process.
Implementation Method 1
detects the toner density in the developer in the development device from a reflection light amount of the developer or a magnetic permeability of the developer with the use of a toner density sensor
Implementation Method 2
detects an image density of the patch image with use of an image density sensor
Data Source
AI summary
An image forming apparatus includes a control unit configured to be able to perform density adjustment control of forming a reference toner image for image density control on an image bearing member and changing a target value of a toner density based on an image density of the reference toner image detected by an image density detection unit. The control unit limits the target value of the toner density within a predetermined range, and changes frequency of execution of the density adjustment control based on the fact that the target value of the toner density is placed at a boundary value.