Rod Lens Array Offset for Image Contrast
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Solution Overview
Problem
Conventional image forming apparatuses face challenges in forming high-quality electrostatic latent images at high speeds due to inefficient light utilization and poor contrast, primarily caused by the arrangement of rod lenses and the displacement of the LED array, which results in a significant amount of light leakage and field curvature issues.
Innovation Solution
The apparatus employs a lens array with rod lenses arranged in three lines, offset from each other, and a light source positioned above the center, ensuring that light is imaged as an erect equi-magnified image on the photosensitive drum, optimizing light distribution and reducing defocus and field curvature effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If rod lenses are arranged in two lines extending in the main-scanning direction, then the device complexity is reduced, but the quantity of light used to form electrostatic latent image decreases and image formation speed slows down
Solution Approach 1:
The patent transitions from a two-line arrangement to a three-line arrangement of rod lenses, adding a dimensional element to the lens array structure. This three-line configuration with offset positioning in the sub-scanning direction increases the effective light collection area and allows more light to contribute to image formation, thereby improving image formation speed while maintaining structural simplicity
2Stability of the object's composition
If LED array is displaced from the center of the lens array in the sub-scanning direction, then the beam profile during scanning is stabilized, but the angle of field to rod lenses becomes non-uniform causing poor image contrast
Solution Approach 1:
The patent introduces asymmetric positioning where the LED array is displaced from the center of the lens array in the sub-scanning direction. This asymmetric arrangement, combined with the three-line offset lens configuration, creates a balanced optical path that stabilizes the beam profile during scanning while maintaining uniform angle of field across all rod lenses, thereby preserving image contrast
3Productivity
If rod lenses are arranged in three lines with offset positioning, then the quantity of light contributing to image formation increases, but the device complexity increases
Solution Approach 1:
The patent segments the lens array into three distinct lines of rod lenses arranged in the main-scanning direction, with each line offset from the others in the sub-scanning direction. This segmentation allows the system to process light from multiple angular directions simultaneously, increasing the quantity of light contributing to image formation while maintaining a modular and manageable structural complexity
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 allows for a higher quantity of light to contribute to the formation of electrostatic latent images, enhancing image contrast and enabling faster image formation while maintaining high quality.
Implementation Method 1
a lens array comprising a plurality of lenses that are arranged in three lines extending in a main-scanning direction such that the lenses of the neighboring lines are offset by one another, the lens array being for imaging light emitted from the light source to form an erect equi-magnified image on a surface of the photosensitive member
Implementation Method 2
a photosensitive member; a light source comprising a plurality of light emitting elements arranged in a line extending in a main-scanning direction
Data Source
AI summary
An image forming apparatus wherein a photosensitive drum is located such that its circumferential surface is exposed to light at a position between an image surface of light that is emitted from an LED at a distance of a half of a pitch of a plurality of rod lenses from a first rod lens of the plurality of rod lenses and that passes through the first rod lens and an image surface of light that is emitted from an LED at a distance of the pitch of the plurality of rod lenses from a second rod lens of the plurality of rod lenses and that passes through the second rod lens.