Adjustable Charge Removal Light Source for Drum Uniformity
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Solution Overview
Problem
Amorphous silicon photosensitive drums in image forming apparatuses face challenges with uneven charge distribution due to difficulties in forming homogeneous films, leading to axial uneven charge distribution, which is hard to adjust effectively with existing charge removal techniques.
Innovation Solution
An image forming apparatus with a charge removing unit that adjusts the distance between light sources and the photosensitive drum surface, allowing for enhanced or reduced charge removal effects to achieve uniform electrostatic charging, comprising a support member with position setting mechanisms to align LEDs in a line along the drum's axis and adjust their distance orthogonally.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a charge removing device with adjustable light-path width is used, then the distribution of charge-removing light intensity can be controlled, but it is practically difficult to adequately adjust the light-path width to obtain desired uniformity
Solution Approach 1:
The patent changes the parameter being adjusted from light-path width to distance between light source and photosensitive drum surface. This parameter change makes the adjustment more effective because distance adjustment directly controls light intensity distribution along the axial direction, whereas light-path width adjustment has limited practical effect on achieving uniform charge distribution.
2Reliability
If amorphous silicon is used as photosensitive drum material, then environmental performance and life duration are improved, but homogeneous film formation becomes difficult causing axial uneven charge distribution
Solution Approach 1:
The charge removing device performs preliminary charge removal before the contact charging process. By removing charges from regions that will have difficulty being charged (such as ends of the photosensitive drum), the system compensates for the inherent non-uniformity of amorphous silicon film formation, ensuring more uniform final charge distribution.
3Manufacturing precision
If light-path width adjustment is used to control charge-removing light intensity distribution, then charge removal can be optimized, but the adjustment mechanism becomes complex and difficult to operate
Solution Approach 1:
The patent simplifies the adjustment mechanism by changing from light-path width adjustment to distance adjustment between light source and photosensitive drum. Distance adjustment is mechanically simpler and more intuitive, while achieving the same or better control over charge removal 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
This approach effectively suppresses uneven charge distribution along the photosensitive drum's axis by adjusting the distance between the light sources and the drum surface, ensuring more uniform electrostatic charging and improved image formation.
Implementation Method 1
charge removing means provided with a light source for emitting given charge-removing light therefrom, and adapted to irradiate the surface of the photoconductor with the charge-removing light from the light source, so as to perform a charge removal operation
Data Source
AI summary
An image forming apparatus has a charge removing unit (31) between a transfer roller (11) for transferring a toner image from a surface of a photosensitive drum (4) to a transfer member and a charging unit (3) for electrostatically charging the surface of the photosensitive drum (4) approximately uniformly, with respect to a rotation direction of the photosensitive drum (4). The charge removing unit (31) includes LEDs (311) to irradiate the surface of the photosensitive drum (4) with charge-removing light. A support (312) supports the LEDs (311) approximately in a line along an axial direction of the photosensitive drum (4). A position setting mechanism (313) allows a position of the support (312) to be changed selectively in a direction orthogonal to the axis of the photosensitive drum (4). Thus, the image forming apparatus can suppress uneven charge-distribution in the axial direction of the photosensitive drum (4).