Asymmetric Laser Scanning Unit for Color Printers
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Solution Overview
Problem
Color laser printers require multiple laser scanning units and sub-scanning optical systems, increasing fabrication costs and affecting print quality due to the complexity and number of components.
Innovation Solution
An asymmetric laser scanning unit with reduced components, featuring sub-scanning optical systems with asymmetric optical paths, where each system includes a light source, entrance optical unit, and exit optical unit, with reflective mirrors and f-θ lenses, to improve linearity and reduce positional deviations in scanning lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple sub-scanning optical systems are used in color laser printers, then print quality and color coverage are improved, but device complexity and fabrication cost increase
Solution Approach 1:
The patent combines multiple sub-scanning optical systems into a shared configuration where multiple imaging surfaces share common optical components including the deflector, entrance optical unit, and exit optical unit. This merging approach maintains the capability to form electrostatic latent images on multiple imaging surfaces while reducing the total number of components compared to having completely separate optical systems for each surface.
Solution Approach 2:
The patent creates a universal optical system where the deflector, entrance optical unit, and exit optical unit serve multiple functions by directing light to multiple different imaging surfaces. The optical paths are configured to be asymmetric, allowing the same optical components to serve different imaging surfaces with different scanning requirements, thereby reducing overall system complexity while maintaining print quality.
2Ease of manufacture
If the number of components in laser scanning units is reduced, then fabrication cost decreases, but scanning linearity and positional accuracy may deteriorate
Solution Approach 1:
The patent employs asymmetric optical paths where the optical configuration from the deflector to each imaging surface is specifically tailored rather than symmetric. This allows each imaging surface to receive optimized light paths with appropriate scanning angles and focal lengths, maintaining scanning linearity and positional accuracy even though components are shared. The asymmetric design enables precise control over the scanning characteristics for each color channel.
Solution Approach 2:
The patent adjusts key optical parameters including scanning angles, focal lengths, and optical path lengths for each sub-scanning system to optimize performance. By carefully controlling these parameters, the system maintains high scanning linearity (variation of ±0.1% or less) and positional accuracy (deviation of ±0.5 dots or less) while using a reduced number of components. The effective scanning angles are maintained within the range of 0.7 to 1.3 times the reference angle.
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 reduces the number of components, improves scanning linearity to ±0.1% and positional deviation to ±0.5 dots, and maintains effective scanning angles between 0.7 to 1.3, thereby enhancing print quality and reducing fabrication costs while allowing for flexible assembly.
Implementation Method 1
a deflector to deflect incident light
Implementation Method 2
the exit optical unit of each sub-scanning optical system may include an f-θ lens
Implementation Method 3
the entrance optical unit may include a collimating lens and a cylindrical lens
Data Source
AI summary
A laser scanning unit and an image forming apparatus that include a deflector to deflect incident light; and a plurality of sub-scanning optical systems using the same reflective surface of the deflector. Each of the sub-scanning optical systems includes a light source, an entrance optical unit disposed between the light source and the deflector to direct light to the deflector, and an exit optical unit to direct the deflected light to imaging surfaces. Optical paths of the sub-scanning optical systems are asymmetric with reference to the deflector.