Developing Device Work Function Hysteresis Suppression
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Solution Overview
Problem
High-speed image forming apparatuses face challenges in maintaining consistent image density due to hysteresis issues in two-component developing systems, where toner remaining on the developer bearing member is not effectively collected, leading to variations in image density and reduced performance over time, especially with low-temperature fixing toners.
Innovation Solution
A developing device with a developer bearing member that includes a toner and carrier, where the toner contains a binder resin and colorant, and an external additive with coalescent particles, and the work function relationship between the carrier and developer bearing member is optimized to ensure the adhesion force between the toner and carrier is greater than the adhesion force between the toner and developer bearing member, preventing toner adherence and promoting consistent development.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a two-component developer is used for high-speed image forming, then productivity is improved, but hysteresis occurs causing image density to decline over time
Solution Approach 1:
The invention changes the physical and chemical parameters of the carrier, specifically controlling the work function to be 4.0 eV or higher, and adjusts the particle size distribution with Dv10 of 5 μm or less and Dv90 of 25 μm or less. These parameter changes ensure consistent toner adhesion to the carrier over multiple development cycles, preventing hysteresis while maintaining high-speed operation capability
Solution Approach 2:
The invention uses a composite structure where inorganic particles are coated with an organic substance on the carrier surface. This composite material approach creates a carrier with controlled work function and surface properties that maintain reliable toner adhesion, resolving the contradiction between high-speed performance and consistent image density
2Productivity
If toner is continuously conveyed through the developing region, then productivity is improved, but toner adheres to the developer bearing member causing hysteresis
Solution Approach 1:
The invention changes the work function parameter of the carrier to 4.0 eV or higher, which fundamentally alters the adhesion characteristics between toner and carrier. This parameter change ensures that toner preferentially adheres to the carrier rather than the developer bearing member, enabling continuous conveyance without hysteresis
Solution Approach 2:
The invention creates different surface properties at different locations by controlling the carrier surface characteristics through organic substance coating. This local quality differentiation ensures that the carrier surface has optimal adhesion properties for toner, while the developer bearing member surface has reduced adhesion propensity, preventing toner accumulation
3Use of energy by moving object
If low-temperature fixing toner is used, then energy consumption is reduced, but hysteresis occurs more prominently
Solution Approach 1:
The invention changes the carrier work function parameter to 4.0 eV or higher, which compensates for the hysteresis tendency of low-temperature fixing toner. This parameter change ensures that even at lower fixing temperatures, the toner maintains consistent adhesion to the carrier throughout continuous operation, preventing image density decline
Solution Approach 2:
The invention uses a composite carrier structure with inorganic particles coated with organic substance, creating surface properties that are particularly effective for low-temperature fixing toner. This composite material approach ensures reliable toner adhesion and prevents hysteresis even when energy consumption is reduced through lower fixing temperatures
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 solution effectively suppresses hysteresis in two-component developing systems, ensuring high-quality full-color images are produced consistently over time by maintaining optimal toner distribution and adhesion forces, even under high-speed and low-temperature conditions.
Implementation Method 1
a work function Wc of the carrier and a work function Ws of the developer bearing member satisfy a relationship of the following formula (1): Ws−Wc≧0.4 eV
Implementation Method 2
the adhesion force between the toner and carrier is greater than the adhesion force between the toner and developer bearing member
Implementation Method 3
the external additive contains coalescent particles each made up of a plurality of coalescing primary particles
Data Source
AI summary
A developing device, including: a developer bearing member, which is disposed opposite to an electrostatic latent image bearing member and which bears thereon a developer for developing an electrostatic latent image formed on the electrostatic latent image bearing member and conveys the developer to a developing region, wherein the developer includes a toner and a carrier, the toner containing: a toner base containing a binder resin and a colorant; and an external additive, wherein the external additive contains coalescent particles each made up of a plurality of coalescing primary particles, and wherein a work function Wc of the carrier and a work function Ws of the developer bearing member satisfy a relationship of the following formula (1):Ws−Wc≧0.4 eV (1).