Dual-Phase Charging Roll Structure for Uniform Electrophotographic Discharge
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Charging rolls for electrophotographic devices face issues with excessive discharge and image unevenness due to local uneven resistance, caused by the addition of large amounts of conductive agents like carbon black, leading to black spots and horizontal streaks in images.
Innovation Solution
A charging roll design featuring a high-resistance first phase and a low-resistance second phase, with specific carbon black types and ratios, and polymers like isoprene rubber and nitrile rubber, to minimize charge attenuation and ensure uniform discharge, comprising a shaft, an elastic layer with a sea-island structure, and a top layer for improved charge blocking and image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large amount of conductive agent (carbon black or ion conductive agent) is added to increase charging ability, then the apparent amount of charge or discharge increases, but excessive discharge occurs in local uneven resistance parts causing black spots and horizontal streaks in images
Solution Approach 1:
The patent applies local quality by creating a multi-phase elastic layer where different regions have different resistance characteristics. The high-resistance first phase (1.6×10^14 to 8.8×10^15 Ω·cm) and low-resistance second phase (1.3×10^2 to 4.9×10^3 Ω·cm) are distributed to provide uniform charge distribution while preventing excessive discharge in local areas, thereby eliminating black spots and horizontal streaks
Solution Approach 2:
The patent uses composite materials by combining multiple phases with different resistance values in the elastic layer. The first phase contains high-resistance characteristics to prevent excessive discharge, while the second phase provides low-resistance pathways for adequate charge distribution, creating a composite structure that balances charging ability with uniformity
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 minimizes charge attenuation from the roll surface due to local uneven resistance, resulting in satisfactory images with reduced horizontal streaks and black spots, by balancing electrostatic capacity and resistance through the strategic use of carbon black types and polymers in the elastic layer.
Implementation Method 1
the second phase contains two types of carbon black: carbon black A, of which an amount of DBP absorption is 115 cm3/100 g or more and 160 cm3/100 g or less; and carbon black B, of which an amount of DBP absorption is 70 cm3/100 g or more and 110 cm3/100 g or less
Implementation Method 2
the elastic layer is constituted of a high-resistance first phase in which a surface resistance value is 1.6×10^14 Ω·cm or more and 8.8×10^15 Ω·cm or less and a low-resistance second phase in which a surface resistance value is 1.3×10^2 Ω·cm or more and 4.9×10^3 Ω·cm or less
Data Source
AI summary
The charging roll 10 for an electrophotographic device comprises a shaft 12, an elastic layer 14 formed on the outer peripheral surface of the shaft 12, and a top layer 16 formed on the outer peripheral surface of the elastic layer 14. The elastic layer 14 is constituted of a high-resistance first phase 14a in which the surface resistance value is 1.6×1014 Ω·cm to 8.8×1015 Ω·cm (inclusive), and a low-resistance second phase 14b in which the surface resistance value is 1.3×102 Ω·cm to 4.9×103 Ω·cm (inclusive). The second phase 14b contains two types of carbon black: carbon black A, of which the amount of DBP absorption is 115 cm3/100 g to 160 cm3/100 g (inclusive); and carbon black B, of which the amount of DBP absorption is 70 cm3/100 g to 110 cm3/100 g (inclusive).