Image Forming Apparatus Photosensitive Member Exposure Control
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Solution Overview
Problem
In electrophotographic image forming apparatuses, the DC charging method struggles with uniformity issues, leading to image defects due to potential irregularities on the photosensitive member, and existing solutions like background exposure cause optical fatigue, reducing the sensitivity and lifespan of the photosensitive member.
Innovation Solution
An image forming apparatus with a controller that adjusts light exposure and charging voltage to minimize exposure to the photosensitive member, using a first light quantity for print areas and a second, smaller light quantity for non-print areas, and selectively applying charging voltage and exposure to specific non-print areas to maintain image quality and reduce optical fatigue.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If background exposure is performed to suppress transfer memory, then image quality is improved, but optical fatigue occurs and photosensitive member sensitivity decreases
Solution Approach 1:
The patent segments the photosensitive member surface into three distinct regions: print areas receiving first light quantity, non-print areas with print history receiving second light quantity (smaller than first), and non-print areas without print history receiving third light quantity (smaller than second). This segmentation allows differential exposure control to suppress transfer memory in critical areas while minimizing optical fatigue across the entire photosensitive member.
Solution Approach 2:
The patent applies local quality by providing different light quantities to different regions based on their specific needs. Print areas receive higher exposure to ensure image quality, while non-print areas receive reduced exposure proportional to their distance from print areas. The charging voltage is also adjusted locally - higher near print areas and lower in distant non-print areas - to maintain potential uniformity without excessive exposure.
2Device complexity
If DC charging method is used to reduce cost and space, then device complexity is reduced, but potential uniformity deteriorates causing image defects
Solution Approach 1:
The patent implements feedback control by using the print history information (whether a print area exists in the main scanning direction) to dynamically adjust both the light quantity and charging voltage for different non-print areas. This feedback mechanism allows the system to compensate for potential irregularities caused by DC charging without adding complex hardware, maintaining potential uniformity through intelligent control.
Solution Approach 2:
The patent changes operational parameters (light quantity and charging voltage) based on the spatial relationship between print and non-print areas. The light quantity is adjusted in proportion to the distance from print areas, and charging voltage is selectively applied or reduced in different non-print regions. This parameter modulation allows DC charging to achieve uniform potential distribution without requiring additional potential irregularity removal means.
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 reduces exposure to the photosensitive member, minimizing optical fatigue and maintaining image quality while extending the lifespan of the apparatus by limiting unnecessary light exposure and adjusting charging voltages to prevent potential irregularities.
Implementation Method 1
a contact charging unit is used as a charging means to uniformly charge a photosensitive member, which is an image bearing member, to a predetermined polarity and potential
Implementation Method 2
an exposing unit configured to form an electrostatic latent image by exposing the surface of the photosensitive member charged by the charging member to light
Implementation Method 3
a developing member configured to develop the electrostatic latent image with toner
Data Source
AI summary
An image forming apparatus includes a rotatable photosensitive member, a charging member, an exposing unit to form an electrostatic latent image by exposing the surface of the photosensitive member charged by the charging member to light and, a developing member to develop the electrostatic latent image with toner. A controller controls so that a predetermined charging voltage is charged and the light is emitted by a low light quantity to a first non-print area, which is a non-print area provided in a region including the print area and the first non-print area with respect to a main scanning direction, and controls so that a charging voltage lower than the predetermined voltage is charged and exposure is not performed on a second non-print area, which is provided in a region including only the non-print area with respect to the main scanning direction.