Charging Roller Spacing Mechanism for Image Forming Apparatus
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Solution Overview
Problem
In electrophotographic image forming apparatuses, the contact charging method can lead to image defects due to deformation of the charging roller when in contact with the photosensitive body for extended periods, and reducing the charging roller diameter increases the risk of slipping, which affects uniform charging and image quality. Additionally, conventional spacing members can introduce unwanted rotational load torque and risk of splattered toner entering the sliding portion, further complicating the issue.
Innovation Solution
An image forming apparatus with a mechanism that switches between spaced and contacting states using a driving force, featuring a spacing member on the charging roller's rotation shaft, a cover portion to prevent toner entry, and a clutch to control rotation transmission, ensuring the photosensitive body and charging roller maintain optimal contact and spacing without increasing rotational load torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the charging roller is reduced in diameter to save space and reduce cost, then the size and cost are improved, but the frictional force between the photosensitive body and the charging roller decreases, increasing the risk of slipping
Solution Approach 1:
The spacing member is positioned in advance to maintain an optimal initial spacing between the charging roller and photosensitive body. This preliminary spacing arrangement ensures that when the charging roller rotates, it maintains sufficient frictional contact without slipping, even with the reduced diameter
Solution Approach 2:
The invention changes the spacing parameter between the charging roller and photosensitive body from direct contact to a controlled spaced state. By adjusting this spacing parameter, the system maintains reliable charging uniformity while allowing the charging roller diameter to be reduced
2Reliability
If the charging roller is kept in contact with the photosensitive body for a long period to maintain charging function, then the charging function is improved, but the charging roller becomes deformed, causing image defects
Solution Approach 1:
The spacing member enables periodic spacing between the charging roller and photosensitive body, allowing the charging roller to rest and recover its shape periodically while maintaining charging function through controlled contact cycles
Solution Approach 2:
The spacing member acts as an intermediary that controls the contact between the charging roller and photosensitive body. It maintains optimal spacing to prevent deformation while allowing sufficient contact for charging function
3Stability of the object's composition
If a removable spacer is used to space apart the photosensitive body and charging roller during shipping, then the deformation problem is improved, but the user operation becomes cumbersome
Solution Approach 1:
The spacing member is designed to be automatically engaged and disengaged through the rotation of the photosensitive body itself. The photosensitive body's own rotation serves to disengage the spacing member, eliminating the need for separate user operations to remove spacers
4Device complexity
If the spacing member is exposed without a cover portion, then the structure is simpler, but splattered toner can enter the sliding portion, increasing rotational load torque
Solution Approach 1:
A cover portion is introduced to enclose the spacing member and protect the sliding portion from toner contamination. This thin-walled cover structure prevents toner entry while maintaining overall structural simplicity
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 solution prevents the increase in rotational load torque of the charging roller, reduces the risk of slipping, and maintains image quality by ensuring consistent contact and spacing between the photosensitive body and charging roller, thereby preventing image defects and deformation.
Implementation Method 1
a contact charging method in which a charging roller that has an elastic layer is brought in contact with a photosensitive body by an urging force of a spring or the like to charge the photosensitive body
Implementation Method 2
an urging portion configured to urge the charging roller in a direction toward the photosensitive drum
Implementation Method 3
the frictional force between the photosensitive body and the charging roller decreases, and thereby there is a high risk that a slip in which the charging roller stops relative to the photosensitive body may occur
Data Source
AI summary
An image forming apparatus comprises a spacing member provided on a rotation shaft of a charging roller, the spacing member configured to include an engaging portion that engages with a rotation member, and to be rotatable between a spaced position at which a spaced state in which a photosensitive drum and the charging roller are spaced apart is maintained, and a released position at which the spaced state is released and the photosensitive drum and the charging roller are caused to be in contact; and a cover portion provided on the rotation shaft of the charging roller, and configured to cover an end face of the spacing member so that a fitting portion of the charging roller and the spacing member is covered.