Image Forming Apparatus Exposure Control for Density Uniformity
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Solution Overview
Problem
Conventional image forming apparatuses using the electrophotographic method face issues with uneven film thickness and potential sensitivity on the photosensitive member, leading to density unevenness in images due to non-uniform charging and exposure, which complicates the correction of potential characteristics and increases the time required for image formation.
Innovation Solution
The apparatus includes an image forming unit, exposure unit, detection unit, storage unit, and control unit that allows for two image forming modes: one where exposure starts regardless of a reference position detection and another where it starts only after detection, with the control unit adjusting exposure intensity based on stored correction data to address uneven potential characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If exposure intensity is adjusted according to surface potential data to correct density unevenness, then image quality is improved, but the complexity of the control system increases
Solution Approach 1:
The system performs preliminary measurement of surface potential distribution before image formation and stores correction data in advance. The exposure control unit retrieves and applies the appropriate correction data during exposure, avoiding real-time complex calculations and simplifying the control system architecture.
Solution Approach 2:
The invention introduces surface potential data and correction data as intermediary elements between the charging device and the exposure device. These data structures serve as mediators that carry information about potential unevenness and enable the exposure control to compensate for it without requiring direct complex interaction between charging and exposure systems.
2Manufacturing precision
If the exposure unit waits for reference position detection before starting exposure, then potential characteristic correction accuracy is improved, but the time from image signal input to first print output increases
Solution Approach 1:
The system dynamically selects between two operational modes: a first mode that prioritizes speed by starting exposure without waiting for reference position detection, and a second mode that prioritizes accuracy by waiting for detection. The switching determination unit chooses the appropriate mode based on real-time conditions, making the system adaptive rather than static.
Solution Approach 2:
The invention changes the operational parameter of exposure start timing based on the selected mode. In the first mode, exposure starts immediately without position detection, while in the second mode, exposure starts only after reference position detection. This parameter change allows the system to balance between speed and accuracy requirements.
3Ease of operation
If the photosensitive member is uniformly charged and exposed with constant light amount, then the charging process is simple, but density unevenness is generated due to potential characteristic unevenness
Solution Approach 1:
The system measures the actual surface potential distribution of the photosensitive member after charging and uses this feedback information to generate correction data. The exposure control unit then applies this feedback by adjusting exposure intensity according to the stored correction data, creating a closed-loop system that compensates for potential unevenness while maintaining simple charging and exposure operations.
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 effectively corrects uneven potential characteristics across the photosensitive member, improving image quality and reducing the time from image signal input to first print output by managing exposure intensity dynamically based on detected positions and stored data.
Implementation Method 1
The exposure device in the image forming apparatus then exposes the charged photosensitive member to form an electrostatic latent image on the photosensitive member
Implementation Method 2
a charging device charges a surface of a cylindrical image bearing member such as a photosensitive member
Implementation Method 3
The electrostatic latent image formed on the photosensitive member is developed using toner
Data Source
AI summary
An image forming apparatus includes an image forming unit, an exposure unit, a detection unit, a storage unit, and a control unit. The image forming unit includes a photosensitive member on which an electrostatic latent image is formed. The exposure unit exposes the photosensitive member. The detection unit detects that a reference position disposed on the photosensitive member has reached a predetermined position. The storage unit stores correction data for correcting unevenness of potential characteristic in the photosensitive member. The control unit controls an exposure intensity of the exposure unit at each position on the photosensitive member based on the correction data.