Hydrin-Rubber Charging Roll to Suppress Polarization and Bleeding
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Solution Overview
Problem
Existing charging rolls for electrophotographic apparatuses experience resistance increase and bleeding of ionic conductive agents due to excessive polarization under electrical load, leading to image defects.
Innovation Solution
A charging roll design incorporating a shaft body with an elastic body layer containing hydrin rubber with a specific chlorine content, an ionic conductive agent, and a salt of a cyclic amidine compound, which suppresses resistance increase and bleeding by coordinating ions effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an ionic conductive agent is added to the base layer rubber of the charging roll, then electrical uniformity is improved, but excessive polarization occurs under electrical load causing resistance increase and image defects
Solution Approach 1:
The patent creates a two-layer structure where the base layer rubber contains the ionic conductive agent for electrical uniformity, while the surface layer rubber has different properties to prevent excessive polarization. This local differentiation allows each layer to perform its specific function without interfering with the other.
Solution Approach 2:
The charging roll uses a composite structure combining base layer rubber with ionic conductive agent and surface layer rubber with different composition. This composite approach allows the system to simultaneously achieve electrical uniformity through ionic conduction while preventing excessive polarization at the surface through the specialized surface layer.
2Reliability
If the amount of ionic conductive agent is excessively increased to suppress excessive polarization, then polarization is reduced, but bleeding of the ionic conductive agent occurs causing image defects
Solution Approach 1:
The patent concentrates the ionic conductive agent in the base layer rubber while the surface layer has different composition. This local concentration allows sufficient ionic conductive agent to be present for polarization control without excessive amounts that would cause bleeding, as the surface layer acts as a barrier.
Solution Approach 2:
The charging roll is divided into functional segments: the base layer containing the ionic conductive agent for polarization control, and the surface layer that prevents bleeding. This segmentation allows each component to perform its function at optimal concentrations without the harmful effects of excessive amounts.
3Duration of action of moving object
If continuous electrical load is applied to the charging roll, then charging function is maintained, but electrical resistance increases due to polarization of the ionic conductive agent
Solution Approach 1:
The surface layer rubber is prepared in advance with specific properties that prevent excessive polarization before it occurs under continuous operation. This preliminary protective structure ensures that when continuous electrical load is applied, the polarization is already constrained, maintaining stable electrical resistance throughout operation.
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
The design maintains low resistance and prevents ionic conductive agent bleeding, even under electrical load, ensuring stable operation and image quality.
Implementation Method 1
the ionic conductive agent in the base layer rubber of the charging roll is polarized, and due to excessively rapid polarization of the ionic conductive agent, the polarized anions and cations are excessively biased toward the + electrode side and the − electrode side, respectively
Implementation Method 2
an ionic conductive mechanism may be required for electrical uniformity and the like
Data Source
AI summary
A charging roll for an electrophotographic apparatus includes a shaft body and an elastic body layer formed on an outer circumferential surface of the shaft body. The elastic body layer contains (a) to (c) below: (a) a hydrin rubber with a chlorine content of 14% or more and 19% or less; (b) an ionic conductive agent; and (c) a salt of a cyclic amidine compound. The hydrin rubber includes a crosslinking agent which is a sulfur crosslinking agent or a peroxide crosslinking agent.