Optical Scanning Apparatus Synchronization Detection
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Solution Overview
Problem
Conventional optical scanning apparatuses face challenges in maintaining stable optical performance due to temperature variations, which affect the position of beam spots, particularly in multi-color image formation, leading to color shift and increased component complexity for synchronization detection.
Innovation Solution
The apparatus employs 2n light sources with a synchronization detecting unit that receives m×n light beams, arranged symmetrically with respect to a sub-scanning cross-section, and includes a first and second scanning lens system facing each other, with synchronization detection performed at one end of each scan line, minimizing color shift by ensuring the synchronization-detecting light is not affected by temperature variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If synchronization detection is performed at both ends of the scan line to reduce beam spot position deviation, then the stability of beam spot position is improved, but the number of photo sensors and electrical control boards increases
Solution Approach 1:
The patent combines the synchronization detection function with the existing photo sensor used for image formation. The same photo sensor that detects the light beam for writing also detects the synchronization signal, eliminating the need for separate synchronization photo sensors. This merging approach reduces component count while maintaining synchronization accuracy.
Solution Approach 2:
The photo sensor is designed to perform multiple functions: both image formation detection and synchronization signal detection. By making the photo sensor universal, the system avoids adding dedicated synchronization detection components, thereby reducing overall device complexity while ensuring reliable beam spot positioning.
2Volume of moving object
If the scanning lens is made compact to reduce apparatus size, then the apparatus volume is reduced, but the optical performance deteriorates due to reduced tolerance and temperature variation
Solution Approach 1:
The patent introduces a pre-correction optical system that compensates for anticipated optical performance deviations before they affect the final beam spot position. By preliminarily adjusting the light path and accounting for temperature variations and tolerance effects, the system maintains stable optical performance in a compact configuration without requiring larger tolerance margins.
Solution Approach 2:
The system dynamically adjusts optical parameters such as focal length and beam path geometry to compensate for temperature variations and manufacturing tolerances. By changing these parameters in real-time or through design optimization, the patent maintains stable beam spot positioning despite the compact lens size that would otherwise reduce tolerance margins.
3Device complexity
If the synchronous optical system path is lengthened to accommodate non-interference placement, then the device complexity is reduced, but the photoreception conditions deteriorate
Solution Approach 1:
The synchronization optical path is merged with the main scanning optical path, allowing both functions to share the same optical components and space. This eliminates the need for a separate synchronous optical system path, maintaining good photoreception conditions while simplifying the overall optical arrangement and reducing device complexity.
Solution Approach 2:
The patent utilizes the sub-scanning direction (vertical dimension) to arrange optical components, allowing the synchronization detection to occur without interfering with the main scanning path in the horizontal dimension. This spatial arrangement in another dimension enables compact integration while maintaining optimal photoreception conditions.
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 color shift to 5 μm/°C or less, minimizing the number of components and electrical control boards, enhancing reliability and reducing manufacturing costs while maintaining accurate write timing determination.
Implementation Method 1
2n (where n≧1) light sources, each light source including m (where m≧1) light emitting units
Implementation Method 2
a scanning lens system that focuses the light beams deflected by the optical deflector on a scanning surface as a beam spot
Implementation Method 3
an optical deflector that deflects light beams emitted by a light source in a main scanning direction
Implementation Method 4
a synchronization detecting unit that receives m×n light beams from the light sources, scans a scanning surface by the light beams emitted by 2n light sources, and determines a write timing
Data Source
AI summary
F-theta lenses, included in scanning lens systems, are arranged on a main scanning plane facing an optical deflector and substantially linearly symmetrically on the main scanning plane with reference to a rotational center of the optical deflector. Each f-theta lens has a no-power portion in the main scanning direction. Synchronization-detecting light passes through the no-power portion of the f-theta lens, thus enabling reduction in color shift due to temperature variation in an image forming apparatus without increasing the cost and complexity in controlling color shift.