Laser Drive Current Adjustment for Photosensitive Drum Lifetime
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Solution Overview
Problem
In color image forming apparatuses using electrophotographic recording systems, variability in photosensitivity characteristics of photosensitive drums due to individual and usage differences poses challenges in effectively controlling the charge potential, leading to issues like fog formation and density reduction, which existing methods struggle to address with a simple configuration.
Innovation Solution
A color image forming apparatus with a light irradiation unit that adjusts its emission levels based on the remaining lifetime of photosensitive members, using a laser driving unit to emit light at different intensities for image and non-image portions, and an acquiring unit to monitor and adjust drive currents for precise charge potential control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a pre-exposure lamp is used to control charge potential, then charge potential control is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts the charge potential control function from a separate pre-exposure lamp system and integrates it into the existing laser exposure device. By utilizing the laser exposure device's light emission capability for both image formation and charge potential control, the patent eliminates the need for a dedicated pre-exposure lamp, thereby reducing device complexity and cost while maintaining effective charge potential control
Solution Approach 2:
The patent makes the laser exposure device perform multiple functions: it serves both for forming electrostatic latent images and for controlling charge potential of the photosensitive drum. This multi-functional approach allows the system to achieve charge potential control without adding separate components, thus resolving the contradiction between control effectiveness and device simplicity
2Manufacturing precision
If drive current is adjusted based on photosensitivity variability, then image density stability is improved, but control complexity increases
Solution Approach 1:
The patent implements a feedback control mechanism where the system acquires information about the photosensitive member's characteristics (such as from sensors or pre-stored data) and uses this information to dynamically adjust the drive current of the laser exposure device. This feedback loop enables automatic compensation for photosensitivity variability, maintaining stable image density without requiring complex manual intervention or additional hardware
Solution Approach 2:
The patent introduces dynamic adjustment of the drive current based on the photosensitive member's remaining lifetime and photosensitivity characteristics. Instead of using a fixed drive current, the system adaptively changes the current levels (first drive current for image portions, second drive current for non-image portions) to match the actual photosensitivity state, thereby maintaining image quality while using a relatively simple control structure
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 maintains consistent charge potential across photosensitive drums, reducing fog formation and ensuring stable image density by adapting to the variability in photosensitivity characteristics, thereby improving the overall image forming process with a simpler and more cost-effective configuration.
Implementation Method 1
laser emission is performed by a laser exposure device to form an electrostatic latent image on the photosensitive drum
Implementation Method 2
a surface of a photosensitive drum is uniformly charged to, for example, −600 V by a charging device
Implementation Method 3
a light irradiation unit irradiating at least one of the charged photosensitive members with light to form electrostatic latent image
Data Source
AI summary
A color image forming apparatus has a plurality of photosensitive members, a light emitting element emitting light, a laser driving unit causing the light emitting element to emit light of a light amount at a first emission level for visualizing the toner image onto a first area where the toner image is to be visualized on the charged photosensitive member and to emit light of a light amount at a second emission level for weak emission onto a second area where the toner is not to be adhered to the charged photosensitive member. In addition, an acquiring unit acquires information associated with a remaining lifetime of each of the photosensitive members, a first drive current adjusting unit adjusts the first drive current, and a second drive current adjusting unit adjusts the second drive current, with the second drive current adjusting unit changing a magnitude of the second drive current in accordance with the information associated with the remaining lifetime of each of the photosensitive members.