Corona Charger Shutter Mechanism for Wire Replacement

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Solution Overview

Problem

In electrophotographic image forming apparatuses, corona chargers generate discharge products that adhere to photosensitive members, leading to reduced surface resistance and inaccurate image formation under high humidity, known as 'image deletion', and existing solutions like shutters require complex arrangements to prevent damage and allow wire replacement.

Innovation Solution

A charging device with a sheet-like shutter mechanism that can be opened and closed without removing or setting the charging wire underneath, using a winding unit and plate spring to regulate the shutter's position and prevent sagging, allowing for easy replacement of the charging wire while maintaining the narrow gap required for efficient charging.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a shutter is arranged in a narrow gap to prevent discharge product adhesion, then image deletion is prevented, but the charging wire cannot be replaced without removing the shutter

Engineering Contradiction:

Improveimage formation accuracyVSAvoidcharging wire replacement

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The shutter mechanism is divided into a shutter body and a shutter holder that can be independently manipulated. The shutter holder can be removed from the shutter body, allowing the charging wire to be replaced through the opening created by this separation, while the shutter body remains in place to maintain image formation accuracy.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The shutter holder acts as an intermediary component between the shutter body and the charging wire. By removing the shutter holder, access is provided to the charging wire for replacement, while the shutter body remains positioned to continue preventing discharge product adhesion.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Strength

If the shutter is made sheet-like to prevent damage to the photosensitive member, then the risk of damage is reduced, but the shutter sags along the longitudinal direction

Engineering Contradiction:

Improvephotosensitive member protectionVSAvoidshutter position stability

Core Design Contradiction:

StrengthVSStability of the object's composition

Solution Approach 1:

A plate spring is introduced to apply elastic force to the shutter, counteracting the gravitational force that causes sagging. The plate spring is positioned to push the shutter upward, maintaining its horizontal orientation and preventing downward sagging along the longitudinal direction.

Inventive Principle:

Principle #8Anti-weight (Counterweight)

Solution Approach 2:

The mechanical properties of the shutter system are changed by introducing the plate spring, which provides elastic restoring force. This changes the force balance on the shutter from purely gravitational to including elastic support, thereby stabilizing the shutter's position and preventing sagging.

Inventive Principle:

Principle #35Parameter changes

3Length of stationary object

If holding members are disposed at the edge of the shutter to regulate sheet variation, then the shutter can be provided in a narrow gap, but the charging wire replacement becomes more difficult

Engineering Contradiction:

Improvenarrow gap maintenanceVSAvoidcharging wire replacement

Core Design Contradiction:

Length of stationary objectVSEase of operation

Solution Approach 1:

The shutter assembly is segmented into the shutter body with holding members and the removable shutter holder. This segmentation allows the shutter holder to be detached, creating access space for charging wire replacement while the holding members remain attached to the shutter body to maintain the narrow gap configuration.

Inventive Principle:

Principle #1Segmentation

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

Enables efficient and safe replacement of the charging wire without operational disruptions, reducing the risk of damage to the photosensitive member and extending its lifespan, while maintaining image formation accuracy even in high-humidity environments.

Implementation Method 1

it became apparent that it was preferable to apply urging force to the shutter with a sheet winding member along the longitudinal direction of the corona charger

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

by disposing a holding member for regulating the variation in a sheet-like member at the edge of a sheet

Methodology Applied

Scientific EffectMechanical Force: Mechanical Force

Implementation Method 3

there is a corona charger that performs corona discharge. The corona charger generates a discharge product such as ozone O3 or nitrogen oxide NOx

Methodology Applied

Scientific EffectCorona discharge: Corona Discharge

Implementation Method 4

When the discharge product generated by using the corona discharge is adhered to the photosensitive member, moisture from the air is absorbed and surface resistance is thus reduced

Methodology Applied

Scientific EffectAbsorption: Absorption (physical)

Data Source

PatentUS8913915B2Charging device

Publication Date: 2014.12.16 CANON KK

AI summary

A corona charger conventionally includes a sheet-like shutter and a holding member configured to hold an end of the shutter, and the replacement of a charging electrode is difficult. To solve this problem, the holding member configured to hold the end of the shutter is set to be movable along the longitudinal direction of a shield to a winding member of the shutter more than a supporting member configured to replaceably support the charging electrode.