Charging Roller Resistance Tuning for Uniform Electrophotographic Charging
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Solution Overview
Problem
Image forming apparatuses using the electrophotographic method experience abnormal discharging and charge unevenness under low-temperature and low-humidity conditions, leading to streak-shaped charge unevenness on electrophotographic photosensitive members.
Innovation Solution
The image forming apparatus includes a photosensitive layer with an antioxidant and a charging roller with a specific resistance range (2×10^5 to 2×10^6 Ω) to maintain uniform charging, suppressing discharge unevenness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional charging methods are used under low-temperature and low-humidity conditions, then the image forming apparatus operates, but abnormal discharging occurs causing streak-shaped charge unevenness
Solution Approach 1:
The patent changes the resistance parameter of the charging roller to a specific range (2×10^5 to 2×10^6 Ω) to prevent abnormal discharging under low-temperature and low-humidity conditions, thereby eliminating streak-shaped charge unevenness while maintaining reliable charging operation
Solution Approach 2:
The patent uses a composite material structure for the charging roller comprising a rubber base material with added conductive particles, creating a material with controlled resistance properties that prevents abnormal discharging while ensuring uniform charging across the photosensitive member surface
2Productivity
If the charging roller has low resistance to ensure good charging, then charging efficiency improves, but abnormal discharging occurs in low-temperature and low-humidity environments
Solution Approach 1:
The patent optimizes the resistance parameter of the charging roller to a specific range (2×10^5 to 2×10^6 Ω) that balances charging efficiency and stability, preventing abnormal discharging in low-temperature and low-humidity conditions while maintaining effective charging performance
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 solution effectively suppresses streak-shaped charge unevenness under low-temperature and low-humidity environments, ensuring consistent image quality.
Implementation Method 1
The charging roller receives, while being in contact with a surface of the image carrier, application of a prescribed DC voltage and thus charges the surface of the image carrier
Implementation Method 2
The exposure device exposes to light the surface of the image carrier charged by the charging roller so as to form an electrostatic latent image having attenuated charge thereon
Implementation Method 3
The developing device supplies toner to the image carrier so as to develop the electrostatic latent image into a toner image
Data Source
AI summary
An image forming apparatus includes an image carrier, a charging roller, an exposure device, and a developing device. The image carrier includes a conductive substrate, an intermediate layer, and a photosensitive layer. The photosensitive layer includes an electric charge generation layer and an electric charge transport layer stacked on a surface of the electric charge generation layer, and the electric charge transport layer contains an antioxidant expressed by a general formula (1) below. In the formula (1), R1 represents an alkyl group having 1 to 10 carbon atoms or a general formula (2) below in which R2 represents an alkyl group having 1 to 10 carbon atoms. The charging roller has a resistance value in a range of 2×105 to 2×106[Ω] when a DC voltage of 500 V is applied thereto under an environment of 10° C. and 10% RH.