Developing Roller Bias Control for Liquid Developer Startup
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Solution Overview
Problem
The conductive developer carrier in electrophotographic image forming apparatuses experiences a reduction in life due to excessive electric current flow when starting up after a long idle period, as the elastic surface layer resistance increases without the presence of a liquid developer, leading to potential damage and shortened lifespan.
Innovation Solution
A liquid developer is placed in the facing section between the developer carrier and contact members, and a bias is applied to each roller during the start-up operation to generate an electric field that moves toner particles, maintaining the developer carrier's health by simulating the normal operational conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bias is applied to the developer carrier and contact members during start-up operation, then excessive electric current flow is suppressed and the surface layer resistance increase is prevented, but the device complexity increases due to the need for controlled bias application timing
Solution Approach 1:
The bias is applied in advance during the start-up operation before normal image formation begins. The control unit detects when the image forming operation has started and applies the bias to the developer carrier and contact members during this preliminary period, preventing excessive current flow before it can occur. This preliminary action resolves the contradiction by protecting the developer carrier without requiring continuous complex control systems.
Solution Approach 2:
The bias application is implemented as a periodic or time-limited action rather than a continuous process. The control unit applies the bias only during the start-up period when the liquid developer has reached the supply position but before normal operation stabilizes. This periodic application reduces the overall complexity while maintaining the protective function during critical periods.
2Reliability
If the liquid developer is supplied to the developer carrier before applying bias, then the electric current flow is controlled, but the start-up time is extended due to the sequential operation requirements
Solution Approach 1:
The liquid developer supply and developer carrier rotation are initiated first as preliminary actions, allowing the liquid developer to reach the supply position on the developer carrier. Only after this condition is met does the control unit apply the bias. This sequencing ensures proper current control while minimizing delays by starting non-conflicting operations in advance.
Solution Approach 2:
The control unit monitors the state of the liquid developer supply and applies the bias only when the appropriate conditions are detected. This feedback mechanism ensures that the bias is applied at the optimal moment - after the liquid developer has reached the supply position but during the start-up phase - thereby controlling electric current flow without unnecessary delays.
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 approach suppresses the increase in resistance of the developer carrier's surface layer, prolonging its life by maintaining optimal operational conditions during start-up and reducing mechanical stress on the elastic layer.
Implementation Method 1
a bias application unit that applies a bias to each of the developing roller, the first conductive roller, and the second conductive roller to generate an electric field in which a normally charged toner in the liquid developer moves from the first conductive roller toward the developing roller
Implementation Method 2
when passing through a facing section (gap of several hundred micrometers) between the developer carrier and a film-forming electrode, the toner is attracted toward the surface of the developer carrier by the action of the electric field generated by the potential difference between the film-forming electrode and the surface of the developer carrier
Implementation Method 3
In the squeeze section, the toner particles are electrophoresed by the action of the electric field generated by the potential difference between the squeeze member and the surface of the developer carrier when passing through the gap between the developer carrier and the squeeze member, and the toner is pressed against the surface of the developer carrier
Implementation Method 4
In the developing section, based on the potential difference formed by the latent image made on the latent image bearing member, the toner particles on the developer carrier move onto the latent image bearing member by electrophoresis in the image region
Implementation Method 5
The toner particles fed to a gap between the developer carrier and the cleaning member, that is, a cleaning section are electrophoresed such that it moves from the developer carrier to the cleaning member by the action of the electric field between the developer carrier and the cleaning member
Data Source
AI summary
In an image forming apparatus, in a case where a power of the apparatus is turned from OFF to ON, a rotation drive unit rotationally drives each of a developing roller, a first conductive roller, and a second conductive roller in a state where a liquid developer supplied to a developer container by a supply device has reached a supply position, and a bias application unit applies a bias to each of the developing roller, the first conductive roller, and the second conductive roller after the developing roller rotates at least once, in the state where the liquid developer supplied to the developer container by the supply device has reached the supply position.