Imaging Scan Unit Bidirectional Zig-Zag Distortion
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Solution Overview
Problem
Micro-mirror-based scan units in image forming devices suffer from low scan duty cycle and zig-zag distortion due to the sinusoidal motion and bidirectional scanning, which limits their application in high-speed and color printing applications.
Innovation Solution
A bidirectional scanning oscillator with a torsion bar and actuator, coupled with optical components that reverse the direction of the reverse sweep portions of the light beam, ensuring that forward and reverse sweep portions are substantially parallel, eliminating zig-zag distortion by using different optical paths for each sweep direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If both forward and reverse sweeps of the laser beam are used to produce scan lines on the photoconductive member, then the scan duty cycle is improved, but zig-zag distortion occurs in the scan lines
Solution Approach 1:
The patent applies the inversion principle by reversing the direction of the reverse sweep portions of the light beam using optical components. Instead of allowing the beam to sweep in opposite directions during forward and reverse motions, the optical components (such as mirrors or prisms) invert the reverse sweep portions to travel in the same direction as the forward sweep portions, thereby eliminating zig-zag distortion while maintaining bidirectional scanning for high duty cycle operation
Solution Approach 2:
The patent introduces optical components as intermediary elements between the oscillating mirror and the photoconductive member. These intermediaries (mirrors or prisms) modify the beam path by reversing the reverse sweep portions, allowing the system to achieve both high scan duty cycle and distortion-free scan lines simultaneously
2Device complexity
If a micro-mirror with sinusoidal motion is used for scanning, then the device complexity is reduced, but the scan duty cycle remains low due to the need for acceptable beam velocity
Solution Approach 1:
The patent enables continuous useful action by utilizing both forward and reverse sweeps of the oscillating micro-mirror for productive scanning. By inverting the reverse sweep portions to travel in the same direction as forward sweeps, the system eliminates wasted motion and achieves continuous productive scanning, significantly improving scan duty cycle while maintaining the simple sinusoidal oscillation mechanism
3Productivity
If bidirectional scanning is used to increase print speed, then the productivity is improved, but the scan spacing uniformity deteriorates causing print defects
Solution Approach 1:
The patent applies inversion to correct the non-uniform scan spacing caused by bidirectional scanning. By reversing the direction of reverse sweep portions through optical components, the system ensures that both forward and reverse sweeps deposit scan lines at uniform intervals, eliminating the spacing variations that would otherwise cause print defects while maintaining high print speed
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 solution significantly reduces or eliminates zig-zag distortion, enabling higher scan duty cycles and facilitating multi-emitter and color applications by ensuring parallel scan lines, thus improving print quality and efficiency.
Implementation Method 1
an oscillator having a reflective surface which oscillates in a predetermined oscillation pattern and reflects the light beam
Implementation Method 2
the optical components defining the second optical path reverse a sweep direction of the corresponding reverse sweep portions of the light beam
Data Source
AI summary
An imaging device scan unit, including an oscillator oscillating in a predetermined oscillation pattern; a light source generating a light beam for deflection by the oscillator and including a forward sweep portion when the oscillator moves in a first direction of the oscillation pattern and a reverse sweep portion when the oscillator moves in a second direction different from the first direction thereof; and components defining at least two optical paths for the light beam, the forward sweep portion of the light beam passes through a first optical path and the reverse sweep portion of the light beam passes through a second optical path, the second optical path reverses a sweep direction of the reverse sweep portion of the light beam such that the forward sweep portion and the reverse sweep portion of the light beam are in the substantially same direction when exiting the scan unit.