Light Irradiating Portion Homogenizes Photosensitive Drum Illumination
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Solution Overview
Problem
In electro-photographic image forming apparatuses, especially in low-temperature and low-humidity environments, the charge potential on photosensitive drums becomes inhomogeneous, leading to 'drum ghost' issues, which degrade image quality due to dimensional and assembling errors in light guide bodies, particularly when the apparatuses are downsized.
Innovation Solution
The image forming apparatus incorporates a light irradiating portion with a first light guide body, a reflecting portion, and a second light guide body, where light from a source is reflected and diffused by a cover member to ensure uniform light distribution on the photosensitive drum, enhancing the homogeneity of light irradiation without increasing the apparatus size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the light guide body is downsized to reduce apparatus size, then the apparatus size is reduced, but the light distribution homogeneity deteriorates due to dimensional and assembling errors
Solution Approach 1:
A diffusing member is introduced as an intermediary component between the light guide body and the photosensitive drum. This diffusing member receives light from the light guide body and redistributes it uniformly across the photosensitive drum surface, effectively decoupling the light distribution quality from the dimensional precision of the light guide body. This allows the apparatus to be downsized while maintaining homogeneous light distribution.
2Length of stationary object
If the distance between the reflecting portion and the photosensitive drum is reduced, then the apparatus size is reduced, but the light amount distribution becomes inhomogeneous due to assembling errors
Solution Approach 1:
The diffusing member serves as a mediator that compensates for the reduced distance between the reflecting portion and the photosensitive drum. By placing the diffusing member in the light path, it ensures that even with shorter distances and potential assembling errors, the light is uniformly distributed across the photosensitive drum surface.
3Manufacturing precision
If multiple mold corrections are performed to achieve accurate light guide body dimensions, then the light distribution homogeneity is improved, but the production time and cost increase
Solution Approach 1:
The diffusing member is designed to compensate for dimensional variations in the light guide body, eliminating the need for multiple mold corrections during production. This robust design allows for faster manufacturing while maintaining homogeneous light distribution, significantly reducing production time and associated costs.
4Volume of moving object
If the light guide body is downsized, then the apparatus size is reduced, but the assembling accuracy requirements increase
Solution Approach 1:
The diffusing member acts as a buffer that tolerates assembling errors, allowing the apparatus to be downsized without proportionally increasing assembling accuracy requirements. The diffusing member's light-redistributing function ensures uniform illumination even with moderate assembling variations.
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 configuration homogenizes light distribution on the photosensitive drum, preventing imaging failures like drum ghost and allowing for downsizing of the image forming apparatus while maintaining image quality, reducing the need for frequent mold corrections and associated costs.
Implementation Method 1
a reflecting portion disposed to face the first light guide body in an intersecting direction intersecting with the rotation axial direction and configured to reflect light from the first light guide body to the first light guide body
Implementation Method 2
a second light guide body comprising a facing portion disposed to face the first light guide body and to oppose the reflecting portion through the first light guide body, and configured to irradiate the photosensitive member with the light transmitted through the first light guide body
Data Source
AI summary
An image forming apparatus includes a rotatable photosensitive member, an image forming portion, and a light irradiating portion configured to irradiate the photosensitive member with light after transferring the toner image onto the transfer material. The light irradiating portion includes a first light guide body configured to extend along a rotation axial direction of the photosensitive member, a light source portion provided to face an end surface portion of the first light guide body in the rotation axial direction, a reflecting portion disposed to face the first light guide body in an intersecting direction intersecting with the rotation axial direction, and a second light guide body comprising a facing portion disposed to face the first light guide body and to oppose the reflecting portion through the first light guide body, and configured to irradiate the photosensitive member with the light transmitted through the first light guide body.