Image Forming Apparatus Charging Frequency Resonance Prevention

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Image forming apparatuses using electrophotography face issues with charging nonuniformity and noise due to resonance between the charging frequency of the alternating bias voltage and the drive frequency of the surface potential sensor, leading to suboptimal image quality and increased noise levels.

Innovation Solution

The introduction of a direct-current bias voltage to the alternating bias voltage, with a frequency relationship of fc≠fvsen×n and fc×n≠fvsen, where fc is the alternating bias voltage frequency and fvsen is the drive frequency of the surface potential sensor, to prevent resonance and improve charging uniformity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If an alternating bias voltage is used for charging the photoconductive element, then charging efficiency is improved, but resonance occurs between the charging frequency and the surface potential sensor drive frequency, causing noise and charging nonuniformity

Engineering Contradiction:

Improvecharging efficiencyVSAvoidnoise and charging nonuniformity

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent applies parameter changes by modifying the frequency relationship between the alternating bias voltage and the surface potential sensor drive frequency. Specifically, it ensures that the charging frequency fc and surface potential sensor drive frequency fvsen satisfy fc ≠ fvsen × n and fc × n ≠ fvsen (where n is an integer), thereby avoiding resonance conditions and reducing noise while maintaining charging efficiency

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces a direct-current bias voltage as an intermediary component added to the alternating bias voltage. This DC bias voltage serves as a mediator that prevents resonance between the alternating charging voltage and the surface potential sensor, thereby eliminating noise and charging nonuniformity while preserving the charging efficiency benefits of the alternating voltage

Inventive Principle:

Principle #24Intermediary (Mediator)

2Manufacturing precision

If the charging frequency is increased to improve charging uniformity, then image quality improves, but resonance with the surface potential sensor drive frequency increases noise levels

Engineering Contradiction:

Improvecharging uniformityVSAvoidnoise levels

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The patent employs parameter changes by establishing specific frequency relationships between the alternating bias voltage and the surface potential sensor. It defines that the charging frequency fc and surface potential sensor drive frequency fvsen must satisfy fc ≠ fvsen × n and fc × n ≠ fvsen, which prevents resonance and noise generation while allowing optimal charging uniformity to be achieved through appropriate frequency selection

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent converts the potentially harmful resonance phenomenon into a beneficial design constraint. By intentionally designing the frequency relationship to avoid resonance conditions (fc ≠ fvsen × n and fc × n ≠ fvsen), the system transforms what would be a harmful resonance effect into a guiding principle for selecting optimal operating frequencies that ensure both charging uniformity and low noise

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 reduces noise in the alternating bias voltage and enhances image quality by maintaining optimal charging conditions on the photoconductive element, resulting in improved image formation and reduced noise levels.

Implementation Method 1

a charging member configured to charge a surface of the image bearing member by adding a direct current bias voltage to at least an alternating bias voltage

Methodology Applied

Scientific EffectElectrostatic charging: Electrostatics

Implementation Method 2

The measuring member has a drive frequency fvsen. The relationship of the frequency fc and the drive frequency fvsen may be expressed as fc≠fvsen×n and fc×n≠fvsen

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Data Source

PatentUS7477856B2Method and apparatus for image forming capable of effectively preventing resonance of frequencies

Publication Date: 2009.01.13 RICOH CO LTD

AI summary

An image forming apparatus including an image bearing member, a charging member, and a measuring member. The image forming member is configured to bear an image. The charging member is configured to charge a surface of the image bearing member when a direct current bias voltage is added to at least an alternating bias voltage which is applied to the charging member, and has a frequency fc of the alternating bias voltage. The measuring member is configured to measure a potential of the surface of the image bearing member, and has a drive frequency fvsen. The relationship of the frequency fc and the drive frequency fvsen is expressed as fc≠fvsen×n and fc×n≠fvsen.