Toner Density Ripple Reduction in Miniaturized Developing Units
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Solution Overview
Problem
Miniaturization and reduced capacity in developing units lead to insufficient mixing of toner and carrier, causing fluctuations in toner density output by sensors, resulting in ineffective control of toner density to the target level, especially in small-scale units.
Innovation Solution
An image forming apparatus with a circulation mechanism, detector unit, and determination unit that executes filter processing to reduce ripples in toner density detection, using a bandstop filter and average unit to stabilize toner replenishment and maintain target density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the developing unit is miniaturized to reduce capacity, then the size of the developing unit is reduced, but the toner and carrier are not mixed sufficiently causing toner density fluctuations
Solution Approach 1:
The circulation mechanism periodically circulates the developer between the first and second chambers at a circulation period of 0.5 to 2 seconds, creating periodic mixing action that ensures sufficient toner-carrier mixing even in miniaturized developing units, thereby maintaining stable toner density
Solution Approach 2:
The developing unit is divided into a first chamber and a second chamber separated by a partition. The circulation mechanism moves developer between these segmented chambers, enhancing mixing efficiency and preventing toner density fluctuations in miniaturized units
2Device complexity
If toner is replenished using sensor-detected toner density when mixing is insufficient, then replenishment control is simplified, but the toner density ceases to be controlled to the target density
Solution Approach 1:
The circulation mechanism operates periodically with a circulation period of 0.5 to 2 seconds to mix toner and carrier before detection, ensuring that sensor readings reflect actual toner density rather than transient mixing states, thereby maintaining precision without increasing control complexity
Solution Approach 2:
The circulation mechanism performs preliminary mixing of toner and carrier before the sensor detects toner density, ensuring that the detected density accurately represents the actual state. This preliminary action prevents erroneous replenishment control while keeping the control system simple
Data Source
AI summary
An image forming apparatus includes a latent image forming unit that forms an electrostatic latent image on an image carrier based on an image signal, a development unit that includes a circulation mechanism that circulates developer in the development unit and develops the electrostatic latent image using the developer, and a detector unit that detects a toner density of the developer in the development unit. A determination unit determines a replenishment amount of toner to the development unit based on the toner density detected by the detector unit, and a replenisher unit replenishes the development unit with toner based on the determined replenishment amount. The determination unit reduces a predetermined ripple that occurs in accordance with a period of circulation of the developer by executing filter processing for reducing the predetermined ripple.