Developing Device Partition for Stable Toner Detection
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Solution Overview
Problem
Existing developing devices in electrophotographic image forming apparatuses face challenges in accurately detecting toner concentration due to the influence of developer pressure and instability in detection results, particularly when the device is first started, which affects the stability of printed image density.
Innovation Solution
The developing device incorporates a partition to separate the first and second conveyance paths, with the toner concentration sensor positioned at the bottom of the second conveyance path close to the first communication portion, optimizing its detection region to minimize developer pressure and stabilize detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the toner concentration sensor is disposed in the conveyance path to detect toner concentration, then the toner concentration can be monitored, but the detection accuracy is reduced due to developer pressure and instability
Solution Approach 1:
A partition wall is introduced as an intermediary structure between the first and second conveyance paths. The partition creates a detection chamber that isolates the sensor from direct developer flow pressure while maintaining toner concentration measurement capability. This mediator structure stabilizes the detection environment without compromising the monitoring function.
Solution Approach 2:
The conveyance path is segmented into distinct regions: a first conveyance path for bulk developer transport, a partition-separated detection chamber for stable measurement, and communication portions for developer flow. This segmentation isolates the detection function from the high-pressure conveyance function, resolving the contradiction between measurement accuracy and detection stability.
2Reliability
If the partition separates the conveyance paths near the sensor, then detection stability is improved, but the device structure becomes more complex
Solution Approach 1:
The partition structure serves multiple functions simultaneously: it separates the conveyance paths to stabilize detection, creates a defined detection chamber, and maintains communication portions for developer flow. This multi-functionality reduces the need for additional separate components, offsetting the structural complexity with functional integration.
Solution Approach 2:
The partition is strategically positioned only in the region where detection stability is needed, rather than completely separating the entire conveyance system. The communication portions maintain necessary developer flow while the partitioned detection chamber provides localized stability. This localized application minimizes overall structural complexity while achieving the reliability improvement.
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 configuration enhances the accuracy and stability of toner concentration detection, ensuring consistent developer supply and maintaining stable image density, even at device startup.
Implementation Method 1
a first conveying screw disposed below the developing roller to face the developing roller, to supply the developer to the developing roller while conveying the developer from one end to another end in a longitudinal direction of the housing
Implementation Method 2
a second conveying screw disposed below and opposite the first conveying screw, to convey the developer from the other end to the one end in the longitudinal direction and form a circulation path for the developer
Implementation Method 3
a toner concentration sensor to detect a toner concentration of the developer, in which a detection region of the toner concentration sensor in the longitudinal direction is located below the partition at a bottom of the second conveyance path
Data Source
AI summary
A developing device that develops a latent image formed on a surface of an image bearer includes a housing, a developing roller, a first conveying screw, a second conveying screw, a partition, and a toner concentration sensor. The first conveying screw is disposed below the developing roller and supplies developer to the developing roller. The second conveying screw is disposed below the first conveying screw and forms a circulation path for the developer together with the first conveying screw. The partition separates a first conveyance path and a second conveyance path in a region excluding a first communication portion formed on one end of the housing and a second communication portion formed on the other end of the housing. A detection region of the toner concentration sensor is located below the partition at a bottom of the second conveyance path and at a position close to the first communication portion.