Dual Spiral Developing Device Toner Sensor Cleaning
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Solution Overview
Problem
Existing developing devices for electro-photographic image forming apparatuses face challenges in accurately detecting toner concentration in two-component developers, leading to potential fogging and reduced image quality due to inefficient mixing and replenishment processes.
Innovation Solution
A developing device with a dual spiral conveyance system and a scraper attachment unit that ensures effective mixing and toner concentration detection by using a first and second spiral blade configuration within the developing container, along with a scraper that cleans the toner concentration sensor, promoting uniform developer circulation and preventing excessive toner supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single spiral blade is used for developer conveyance, then the structure is simple, but the mixing efficiency is insufficient leading to inaccurate toner concentration detection
Solution Approach 1:
The stirring-conveyance member is segmented into two functional components: a first spiral blade for developer conveyance and a second spiral blade for enhanced mixing. This segmentation allows each blade to perform its specific function optimally, improving toner concentration detection accuracy while maintaining reasonable structural complexity through modular design
Solution Approach 2:
The second spiral blade is designed to serve multiple purposes: it enhances mixing efficiency, promotes uniform developer circulation, and works in conjunction with the first spiral blade to maintain overall developer flow. This multi-functionality improves detection accuracy without proportionally increasing device complexity
2Reliability
If toner replenishment is performed without accurate concentration detection, then the operation is simple, but fogging occurs and image quality deteriorates
Solution Approach 1:
A toner concentration sensor provides real-time feedback on developer toner concentration, enabling automated control of the toner replenishment process. The sensor detects concentration changes and triggers replenishment only when necessary, preventing fogging and maintaining image quality through precise, demand-based toner addition
Solution Approach 2:
The system performs preliminary toner concentration detection before initiating replenishment operations. This preliminary action ensures that toner is added only when the concentration falls below optimal levels, preventing both fogging from excessive toner and poor image quality from insufficient toner
3Measurement precision
If the scraper is positioned without considering spiral blade intersections, then the sensor cleaning is effective, but developer circulation is disrupted
Solution Approach 1:
The scraper is positioned at a specific location that avoids the intersection zones of the spiral blades while maintaining effective contact with the toner concentration sensor. This localized positioning ensures that the scraper performs its cleaning function without interfering with the overall developer circulation pattern maintained by the spiral blades
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 of toner concentration detection, reduces fogging, and maintains optimal image quality by ensuring precise toner replenishment and distribution within the developing device.
Implementation Method 1
a first spiral blade which is formed on an outer circumferential surface of the rotation shaft and conveys the developer in an axial direction of the rotation shaft when the rotation shaft rotates
Implementation Method 2
a sub conveyance blade (a second spiral blade) which produces a conveying effect in a second direction, which is a direction toward the other side in the axial direction, with respect to part of the developer, along with rotation of the shaft member. With this configuration, the sub conveyance blade causes convection in part of developer conveyed, and a stirring effect is promoted
Implementation Method 3
The scraper is flexible and attached to the second stirring-conveyance member, and cleans a detection surface of the toner concentration sensor with a free end thereof by rotating with the second stirring-conveyance member
Implementation Method 4
The toner concentration sensor is disposed on an inner wall surface of the second conveyance chamber, and detects a toner concentration in developer
Data Source
AI summary
A developing device includes a developing container, first and second stirring-conveyance members, a developer carrier, a toner concentration sensor, a scraper, and a scraper attachment unit. The second stirring-conveyance member includes a rotation shaft, a first spiral blade to convey developer in an axial direction, and a second spiral blade to overlap a region where the first spiral blade is formed, which is opposite to the first spiral blade in phase, and lower than the first spiral blade in height in a radial direction. An absent region, where the second spiral blade does not exist, is formed in one pitch of the first spiral blade, the one pitch facing the toner concentration sensor. The scraper attachment unit is formed to extend, along a straight line passing through intersection points of the first and second spiral blades and parallel to the rotation shaft, into the absent region.