Printer Exposure Light Source Layout for Stable Drum Illumination
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Solution Overview
Problem
Existing exposure heads in electrophotographic printers face challenges in maintaining consistent light intensity and image quality due to attachment errors and misalignment, particularly when using LED or organic EL light sources with lens arrays.
Innovation Solution
The proposed light source apparatus includes a configuration with first and second light-emitting units positioned differently in two orthogonal directions, along with a lens unit that satisfies specific inequalities to minimize light fluctuations and attachment errors, ensuring consistent light condensation onto a rotatable target surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a lens unit is used to condense light from light-emitting units onto a photosensitive drum, then light condensation efficiency is improved, but attachment errors and misalignment cause light intensity fluctuations and image quality degradation
Solution Approach 1:
The light source is divided into multiple light-emitting units (first and second light-emitting units with multiple light-emitting elements each) arranged in specific patterns. This segmentation allows the system to maintain consistent light distribution even when attachment errors occur, as the modular structure provides redundancy and distributes the impact of misalignment across multiple elements rather than concentrating it in a single source.
Solution Approach 2:
The patent employs asymmetric arrangement of light-emitting units where the first and second light-emitting units are positioned at different locations in both first and second directions. The light-emitting elements within each unit are also asymmetrically distributed. This asymmetric configuration, combined with the lens unit, creates an optical system that is less sensitive to attachment errors and maintains more consistent light intensity on the photosensitive drum despite misalignment.
2Manufacturing precision
If light-emitting units are arranged in specific patterns to reduce attachment error effects, then image quality is improved, but device complexity increases
Solution Approach 1:
Multiple light-emitting units are merged into a single integrated light source assembly that works in conjunction with one lens unit. The first and second light-emitting units, each containing multiple light-emitting elements, are combined in a specific spatial arrangement that achieves the desired light distribution pattern. This merging approach simplifies the overall structure compared to having separate independent light sources, while still providing the benefits of reduced attachment error sensitivity and improved image quality.
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 effectively reduces light amount fluctuations caused by attachment errors, enabling the formation of high-quality images with minimal density variations, even with slight misalignments, and maintains a compact apparatus size.
Implementation Method 1
a lens unit configured to condense light from the first light-emitting unit and the second light-emitting unit onto a target surface that is rotatable
Implementation Method 2
a light amount that is emitted from a light-emitting unit including the second surface tilted relative to the first surface, is reflected by the lens unit, is reflected by the second surface of another light-emitting unit, and enters the lens unit is less than a light amount in a case where the second surface is not tilted
Data Source
AI summary
A light source apparatus includes a first light-emitting unit and a second light-emitting unit having centers located at different positions in a first direction and a second direction orthogonal to the first direction, and a lens unit configured to condense light from the first light-emitting unit and the second light-emitting unit onto a target surface that is rotatable. Each of the first light-emitting unit and the second light-emitting unit includes a plurality of light-emitting elements arranged in the first direction. A predetermined inequality is satisfied.