Optical Scanning Apparatus Asymmetric Synchronization Detection
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Solution Overview
Problem
Conventional optical scanning apparatuses face challenges in reducing size and production cost while maintaining optical performance, particularly in tandem image forming systems, due to interference issues with light sources and synchronization detecting units, which lead to misalignment and degradation of image quality during temperature changes.
Innovation Solution
The optical scanning apparatus employs a configuration with a polygon mirror, semiconductor lasers, and a synchronization detecting unit that receives light beams deflected by the polygon mirror on the same side as the light sources, using a single scanning lens close to the polygon mirror to minimize size and cost, and optimizing the optical path to maintain alignment and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the optical deflector is shared by a plurality of scan target surfaces to reduce size and production cost, then the number of optical deflectors is reduced, but light from one side interferes with the light source board, requiring additional reflecting mirrors that increase size and complexity
Solution Approach 1:
The patent applies asymmetry by arranging light sources and synchronization detecting units at asymmetric positions relative to the optical deflector. Specifically, light sources are positioned on one side while synchronization detecting units are positioned on the opposite side, creating an asymmetric layout that prevents light interference between the light source board and synchronization detecting units, thereby eliminating the need for additional reflecting mirrors
2Object-affected harmful factors
If many reflecting mirrors are used to avoid light interference, then light interference is avoided, but the synchronization beam departs from the photodetector due to accumulation of tilts, degrading detecting accuracy
Solution Approach 1:
The patent extracts the synchronization detecting unit from the vicinity of the light source board and positions it on the opposite side of the optical deflector. This separation removes the harmful light interference effect while maintaining a compact optical path for synchronization detection, thereby preserving detection accuracy without requiring multiple reflecting mirrors
3Area of stationary object
If the scanning optical system uses a single lens close to the optical deflector to reduce size, then the footprint is reduced, but temperature changes cause misalignment of the scanning point
Solution Approach 1:
The patent incorporates a synchronization detecting unit that provides feedback signals to the control system. This feedback mechanism allows the system to detect and compensate for misalignment caused by temperature changes, maintaining scanning point accuracy while using a single lens configuration for compactness
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 reduces the footprint and production cost of the optical scanning apparatus, minimizes color shifts during temperature changes, and enhances the accuracy of synchronization detection, resulting in high-quality images with reduced optical performance degradation.
Implementation Method 1
an optical deflector having a plurality of deflecting-reflecting surfaces each of which deflects a corresponding one of the light beams emitted by a corresponding one of the light sources
Implementation Method 2
form an optical spot on a scan target surface by focusing the deflected light beam on the surface using a scanning image-forming optical system, such as an f-theta lens
Implementation Method 3
a synchronization detecting unit that receives a synchronization signal from one of a start point and an end point of scanning with the light beam on the scan target surfaces
Data Source
AI summary
Synchronization detecting units detect synchronization signals by receiving the light beam deflected to one side of a light source on one side of an optical deflector and receiving the light beam deflected to an opposite side of an optical axis of a scanning optical system from the light source on the other side of the optical deflector. Photodetectors that detect the synchronization signals are arranged on the opposite side of an optical axis of a scanning optical system from the light sources and on a side closer to the scanning optical system that detects the synchronization signals by receiving the light beam deflected to the light source.