Toner Density Control via Feedback in Image Forming Apparatus
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Solution Overview
Problem
In electrophotographic image forming apparatuses, maintaining stable toner density is challenging due to the inability to accurately confirm toner replenishment and consumption, leading to deteriorated image quality when toner density falls out of the appropriate range.
Innovation Solution
An image forming apparatus with a toner storage, developing portion, toner replenishing mechanism, density detecting system, and control mechanisms that form and detect toner patches to compare densities, adjusting the developing bias to maintain toner density within specific control ranges, ensuring accurate toner replenishment or consumption to stabilize image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If toner replenishment is performed based on pixel count cumulative value, then toner supply can be predicted, but it is impossible to confirm whether the toner has been replenished correctly or indicate the actual toner consumption
Solution Approach 1:
The patent implements feedback control by detecting the density of a reference toner image formed on the photoreceptor drum and comparing it with a target density value. This closed-loop feedback mechanism allows the system to confirm whether toner has been replenished correctly and to measure actual toner consumption, resolving the contradiction between predicting toner supply and confirming replenishment accuracy.
Solution Approach 2:
The patent replaces the mechanical/pixel-count-based toner measurement method with an optical detection system. By using a density sensor to optically measure the density of the reference toner image, the system achieves precise measurement of actual toner consumption, substituting the inadequate pixel count method with a more accurate optical measurement approach.
2Device complexity
If toner density control is not performed, then the developing system is simpler, but image quality deteriorates due to toner density falling out of the appropriate range
Solution Approach 1:
The patent employs feedback control by continuously monitoring the density of the reference toner image and adjusting the developing bias accordingly. This feedback mechanism maintains toner density within the appropriate range, ensuring stable image quality while using a relatively simple control approach that only requires density detection and bias adjustment.
Solution Approach 2:
The patent controls toner density by adjusting the developing bias parameter. When the detected reference toner image density deviates from the target value, the system changes the developing bias to bring the density back into the appropriate range. This parameter-based control method effectively maintains image quality without requiring complex system modifications.
3Productivity
If a dual-component developer is used for high-speed development, then development speed increases, but toner is consumed and reduced requiring continuous replenishment
Solution Approach 1:
The patent uses feedback control to monitor reference toner image density and adjust developing bias in real-time during high-speed operation. This allows the system to maintain optimal toner density even as toner is consumed during rapid development operations, ensuring both high productivity and stable toner supply.
Solution Approach 2:
The patent performs preliminary density measurement by forming a reference toner image on the photoreceptor drum before normal image formation. This preliminary action allows the system to anticipate toner consumption and adjust replenishment timing, ensuring toner is available when needed for high-speed development while optimizing the replenishment schedule.
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 system effectively maintains stable toner density by forcibly replenishing or consuming toner based on developing bias differences, ensuring image forming quality by keeping toner density within predetermined ranges, even when the toner density significantly deviates from the appropriate range.
Implementation Method 1
a photoreceptor drum for carrying a toner image visualized by the developing portion
Implementation Method 2
a toner density detecting portion for detecting a toner density of the developing portion
Implementation Method 3
an image density detecting portion for detecting a density of the toner patch
Data Source
AI summary
Provided are an image forming apparatus that, when a difference between a developing bias in correcting an image density and a reference developing bias has a value not less than a prescribed value that is set preliminarily, replenishes or consumes a toner forcibly, executes correction of the image density again, and controls the developing bias in such a manner that a toner density is controlled to fall within an appropriate range, and an image forming method using the same. When a difference between a developing bias value after correction of the image density and the reference developing bias becomes larger than the prescribed value to the plus side or the minus side, a toner density control portion performs control to consume or replenish a toner forcibly.