Developing Device Oscillating Electric Field Hysteresis Prevention
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Solution Overview
Problem
The hybrid developing method in electrophotographic image forming apparatuses experiences a hysteresis phenomenon due to toner accumulation and uneven charge distribution, leading to image quality issues and reduced device lifespan.
Innovation Solution
A developing device with an oscillating electric field between conveyance members that biases the time average field strength to facilitate efficient toner supply and recovery, using a developer with a toner and carrier charged to different polarities, and incorporating charged particles to maintain stable toner chargeability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a magnetic brush is directly brought into contact with an image bearing body for development, then development can be performed, but irregular sweeping occurs resulting in sliding noise in images
Solution Approach 1:
A transfer member is introduced as an intermediary between the magnetic brush and the image bearing body. The transfer member receives the magnetic brush from the developer bearing body and transfers it to the image bearing body for development, preventing direct contact between the magnetic brush and image bearing body, thereby eliminating irregular sweeping and sliding noise while maintaining development performance
2Device complexity
If toner is charged by frictional contact with a friction charge member, then the structure can be simple and small, but the toner is subjected to strong stress causing deterioration and reduced chargeability
Solution Approach 1:
The mechanical friction charging method is replaced with an electrical charging method using a corona charger or similar electrical charge member. This substitution eliminates the strong mechanical stress and contact pressure that cause toner deterioration, while maintaining the ability to charge toner to predetermined polarity, thereby improving toner chargeability and device reliability
3Reliability
If the time ratio for collecting toner from the developing roller is increased, then the hysteresis phenomenon is reduced, but the toner supply performance is damaged
Solution Approach 1:
An oscillating electric field is applied between the conveying roller and developing roller, dynamically adjusting the field strength and direction over time. This dynamic field enables efficient toner collection during the recovery phase while maintaining adequate toner supply during the supply phase, resolving the contradiction between hysteresis prevention and supply performance
Solution Approach 2:
The oscillating electric field applies periodic action with specific frequency and amplitude, creating alternating phases of toner supply enhancement and toner collection enhancement. This periodic modulation allows the system to achieve both efficient toner supply and effective toner recovery without sacrificing either function
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
Prevents hysteresis phenomenon, ensures efficient toner recovery without damaging supply performance, and maintains long-term toner chargeability, thereby improving image quality and device longevity.
Implementation Method 1
a first electric field forming unit which forms a first electric field between the first conveyance member and the second conveyance member to move the toner in the developer retained by the first conveyance member to the second conveyance member
Implementation Method 2
the toner being charged to a first polarity by frictional contact between the toner and the carrier
Implementation Method 3
second electric field forming unit which forms a second electric field between the second conveyance member and the electrostatic latent image bearing body to move the toner retained by the second conveyance member to an electrostatic latent image on the electrostatic latent image bearing body
Data Source
AI summary
A developing device is disclosed that is capable of preventing the hysteresis phenomenon, and which contains a toner and a carrier. The toner and the carrier are charged to different polarities by frictional contact thereof. The developing device has a first conveyance member and a second conveyance member which faces an electrostatic latent image bearing body via the second region. An electric field forming device forms a first electric field between the first conveyance member and the second conveyance member to move the toner in the developer retained by the first conveyance member to the second conveyance member, and forms a second electric field between the second conveyance member and the electrostatic latent image bearing body to move the toner retained by the second conveyance member to an electrostatic latent image of the electrostatic latent image bearing body.