Charging Member Surface Shape for Latent Image Position Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In image forming apparatuses using electrophotographic systems, density unevenness occurs due to vibration of the exposure device caused by the rotation of the charging member, leading to variations in the position where latent images are formed, resulting in image density inconsistencies.
Innovation Solution
The image forming apparatus is designed with a charging member that has a specific surface shape with an amplitude satisfying the formula (F−5)≤(V/L)≤(F+5) of 0.80 μm or less, where F is the natural frequency of the exposure device and V is the rotational peripheral velocity of the charging member, to suppress vibration and resonance, thereby stabilizing the position for forming latent images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the charging member rotates at high speed to increase productivity, then image formation speed improves, but vibration and resonance occur causing density unevenness
Solution Approach 1:
The patent changes the surface shape parameters of the charging member by controlling the amplitude Af to be 0.80 μm or less at specific periods Lf that satisfy the resonance condition (F−5)≤(V/L)≤(F+5). This parameter control suppresses vibration-induced density unevenness while allowing high-speed rotation for improved productivity.
2Manufacturing precision
If the surface shape of the charging member is made smoother to reduce vibration, then density unevenness decreases, but manufacturing complexity increases
Solution Approach 1:
Instead of requiring universally smooth surfaces, the patent specifies precise amplitude parameters Af≤0.80 μm only at critical periods Lf that cause resonance. This targeted approach maintains manufacturing feasibility while achieving the necessary surface quality for suppressing density unevenness.
Solution Approach 2:
The patent uses a mandrel with a predetermined surface shape to form the charging member's surface during manufacturing. This copying approach allows precise control of the surface profile (amplitude Af≤0.80 μm at specific periods) while simplifying the manufacturing process through mold-based replication rather than complex post-processing.
3Stability of the object's composition
If the amplitude of surface shape is reduced to suppress resonance, then vibration-induced position variation decreases, but manufacturing precision requirements increase
Solution Approach 1:
The patent defines specific parameter ranges for the surface shape: amplitude Af≤0.80 μm at periods Lf satisfying (F−5)≤(V/L)≤(F+5). These quantified parameters provide clear manufacturing targets that balance position stability requirements with achievable manufacturing precision.
Solution Approach 2:
By using a mandrel with a predetermined surface shape during manufacturing, the patent enables precise replication of the required surface profile (amplitude Af≤0.80 μm at specific periods). This copying method simplifies achieving the necessary surface shape control compared to direct machining or finishing operations.
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 effectively suppresses density unevenness in the images by minimizing vibration-induced variations, ensuring consistent image quality even when the exposure device is close to resonating with the charging member's rotational frequency.
Implementation Method 1
a charging device that charges the surface of the image holding member and includes a charging member disposed in contact with the surface of the image holding member
Implementation Method 2
an exposure device that forms a latent image by exposing the charged surface of the image holding member
Implementation Method 3
the amplitude Af with a period Lf (mm) satisfying the formula (F−5)≤(V/L)≤(F+5) is 0.80 μm or less... to suppress vibration and resonance, thereby stabilizing the position for forming latent images
Data Source
AI summary
An image forming apparatus includes an image holding member, a charging device that charges a surface of the image holding member and includes a charging member disposed in contact with the surface of the image holding member, an exposure device that forms a latent image by exposing the charged surface, a developing device that forms a toner image by developing the latent image with toner, and a transfer device that transfers the toner image formed to a recording medium. An amplitude Af with a period Lf (mm) satisfying the formula (F−5)≤(V/L)≤(F+5) is 0.80 μm or less where F is the natural frequency (Hz) of the exposure device, V is the rotational peripheral velocity (mm/s) of the charging member, and L is the period (mm) in analysis of the circumferential direction period of the surface shape of the charging member.