Intermediate Transfer Member Resistivity Control for Image Defects
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Solution Overview
Problem
Existing image forming apparatuses using electrophotographic processes face challenges in efficiently transferring toner images due to interference currents between the secondary and primary transfer portions, leading to image defects and reduced transfer efficiency.
Innovation Solution
The image forming apparatus includes an intermediate transfer member with a volume resistivity ranging from 5×10^7 Ω·cm to 2×10^11 Ω·cm and a surface resistivity ratio ρs1/ρs2 ≥ 1.5, which reduces interference currents and stabilizes the primary transfer process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the intermediate transfer member has low volume resistivity to facilitate charge distribution, then secondary transfer efficiency improves, but primary transfer process becomes unstable due to interference currents
Solution Approach 1:
The intermediate transfer member is designed with different electrical resistance characteristics for different purposes: the volume resistivity is controlled to be within 1×10^7 Ω·cm to 1×10^9 Ω·cm to allow charge distribution for secondary transfer, while the surface resistivity is controlled to be 1×10^9 Ω/sq or higher to prevent interference currents during primary transfer. This local differentiation of electrical properties resolves the contradiction between secondary transfer efficiency and primary transfer stability.
2Reliability
If the intermediate transfer member has high surface resistivity to prevent interference currents, then primary transfer stability improves, but charge distribution for secondary transfer becomes insufficient
Solution Approach 1:
The intermediate transfer member utilizes different resistance mechanisms at different levels: high surface resistivity (1×10^9 Ω/sq or higher) prevents lateral charge leakage and interference currents, while adequate volume resistivity (1×10^7 Ω·cm to 1×10^9 Ω·cm) allows vertical charge distribution through the material thickness. This layered resistance structure simultaneously achieves primary transfer stability and secondary transfer efficiency.
3Device complexity
If conventional intermediate transfer members are used without controlled resistivity, then device complexity is low, but image defects occur due to interference currents between transfer portions
Solution Approach 1:
The intermediate transfer member's electrical resistance parameters are precisely controlled within specific ranges: volume resistivity of 1×10^7 Ω·cm to 1×10^9 Ω·cm and surface resistivity of 1×10^9 Ω/sq or higher. By changing and controlling these physical parameters, the patent eliminates interference currents and image defects without adding complex structural elements, maintaining device simplicity while solving the harmful effect.
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 configuration effectively reduces interference currents, enhancing the primary transfer efficiency and preventing image defects, while maintaining a stable secondary transfer process.
Implementation Method 1
The intermediate transfer member has a volume resistivity from 5×10^7 Ω·cm to 2×10^11 Ω·cm inclusive, and a relation ρs1/ρs2≥1.5 is satisfied, where ρs1 denotes a surface resistivity which is measured from the outer circumferential surface and ρs2 denotes a surface resistivity which is measured from an inner circumferential surface
Implementation Method 2
a voltage application member configured to apply a voltage to the image carrier, and a secondary transfer member in contact with an outer circumferential surface of the intermediate transfer member, wherein the secondary transfer member is configured to perform secondary transfer of the toner image carried on the intermediate transfer member onto a transfer material
Data Source
AI summary
An image forming apparatus includes an image carrier to carry a toner image, intermediate, primary, and secondary transfer members, and a voltage application member. The voltage application member applies a voltage to the image carrier. The secondary transfer member is in contact with an outer circumferential surface of the intermediate transfer member. The toner image carried on the image carrier is primarily transferred onto the intermediate transfer member in a state where the voltage application member applies the voltage to the image carrier. The intermediate transfer member has a volume resistivity from 5×107 Ω·cm to 2×1011 Ω·cm inclusive. A relation ρs1/ρs2≥1.5 is satisfied, where ρs1 denotes a surface resistivity which is measured from the outer circumferential surface of the intermediate transfer member and ρs2 denotes a surface resistivity which is measured from an inner circumferential surface of the intermediate transfer member.