Optical Scanning Device Aperture Member Stray Light Control
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Solution Overview
Problem
Stray light generated by the cylindrical lens in an optical scanning device can enter the polygon mirror, causing ghost images and deteriorating image quality in image forming apparatuses like color laser printers.
Innovation Solution
An aperture member with strategically positioned apertures is placed between the cylindrical lens and the polygon mirror to obstruct stray light, reducing its reflection and entry into the polygon mirror, thereby preventing ghost images and maintaining image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a cylindrical lens is used to collect and focus laser beams onto the polygon mirror, then the beam collection efficiency and scanning precision are improved, but stray light is generated that enters the polygon mirror and causes ghost images
Solution Approach 1:
A black coating layer is applied to the cylindrical lens surface to act as an intermediary that absorbs stray light before it can enter the polygon mirror. This mediator prevents the harmful interaction between the lens and the mirror while maintaining the optical functionality of the lens for beam collection and focusing.
Solution Approach 2:
The stray light generated by the cylindrical lens is converted from a harmful factor into a beneficial one by using it to highlight the need for the black coating. The coating transforms the problematic stray light reflection into useful light absorption, eliminating ghost images while preserving the lens's focusing capability.
2Object-generated harmful factors
If the aperture member is added to block stray light, then ghost images are prevented, but the device complexity increases
Solution Approach 1:
The black coating layer is merged with the cylindrical lens structure, integrating the stray light absorption function directly into the existing lens component. This combination eliminates the need for separate stray light blocking components while maintaining the lens's primary optical function, thus reducing device complexity.
Solution Approach 2:
The cylindrical lens is given multiple functions: it continues to collect and focus laser beams while simultaneously serving as a substrate for the black coating that absorbs stray light. This multi-functionality reduces the need for additional components and simplifies the overall device 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
The solution effectively reduces stray light reaching the photosensitive drums, preventing ghost images and improving the overall image quality formed on the recording sheets.
Implementation Method 1
the laser beams pass through the cylindrical lens, are collected on and are reflected by the rotating polygon mirror
Implementation Method 2
the laser beams pass through the cylindrical lens, are collected on and are reflected by the rotating polygon mirror, are deflected in a main scanning direction
Data Source
AI summary
An optical scanning device is configured to cause a light beam to scan a photosensitive drum to form a latent image on the photosensitive drum. The optical scanning device includes light emitting units configured to emit light beams and a light deflecting unit having deflecting surfaces and being configured to cause the light beams emitted from the light emitting units to reflect at the deflecting surfaces and deflect and scan in a main scanning direction. Also, the device includes a lens disposed between the light emitting units and the light deflecting unit, the lens being configured to cause the light beams emitted from the light emitting units to be directed along the main scanning direction to the deflecting surfaces, and an aperture member disposed between the lens and the light deflecting unit, and having apertures formed in line in a sub scanning direction perpendicular to the main scanning direction.