Optical Scanning Device Tilted Negative Refractive Lens Beam Alignment
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Solution Overview
Problem
In optical scanning devices, deviations in the sub-scanning direction interval of plural light beams emitted from multiple light sources can lead to image defects such as banding and density unevenness in periodic images, particularly in horizontal line or halftone images, due to improper alignment and variations in optical components.
Innovation Solution
The introduction of an optical element group with a negative refractive power along the sub-scanning direction, specifically a cylindrical concave lens, which can be tilted on an axis parallel to the main scanning direction to adjust the interval of the light beams, ensuring precise alignment and minimizing image defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple light emitting portions are two-dimensionally arranged to increase resolution and speed, then productivity and measurement precision are improved, but manufacturing precision deteriorates due to difficulty in controlling beam interval alignment
Solution Approach 1:
A tiltable optical element with negative refractive power is introduced as an intermediary component between the light source and the scanning system. This optical element mediates the beam paths from multiple light emitting portions, enabling adjustment of the intervals in the sub-scanning direction through tilting. The intermediary optical element decouples the alignment control from the light source positioning, allowing independent adjustment of beam intervals without modifying the light source arrangement.
2Measurement precision
If optical components are used to focus and scan light beams, then measurement precision is improved, but device complexity increases due to additional optical elements requiring alignment
Solution Approach 1:
The optical element is designed to be tiltable around an axis parallel to the main scanning direction, transforming the static optical system into a dynamic one. By tilting the optical element, the intervals of light beams in the sub-scanning direction can be adjusted without changing the physical positions of the light source or other optical components. This dynamic adjustment mechanism simplifies the overall system complexity by providing a single degree of freedom for controlling beam intervals.
3Speed
If light beams are deflected by a rotary polygonal mirror for scanning, then speed is improved, but manufacturing precision deteriorates due to sensitivity to optical component variations
Solution Approach 1:
The invention changes the optical parameter of beam interval in the sub-scanning direction by tilting the optical element with negative refractive power. This parameter adjustment compensates for variations and deviations that occur during manufacturing and operation of the rotary polygonal mirror and other optical components. By providing continuous adjustment capability, the system can adapt to manufacturing tolerances and maintain precise beam alignment despite component variations.
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 effectively adjusts the sub-scanning direction interval of the light beams, preventing banding and density unevenness, thereby enhancing the quality of periodic images by maintaining the required beam alignment and tolerance.
Implementation Method 1
plural optical element groups disposed between the light source and the deflection unit and including an optical element having a negative refractive power along a sub-scanning direction intersecting the main scanning direction
Data Source
AI summary
An optical scanning device includes a light source having plural light emitting portions, a deflection unit that deflects and scans plural light beams emitted from the light source in a main scanning direction, and plural optical element groups disposed between the light source and the deflection unit and including an optical element having a negative refractive power along a sub-scanning direction intersecting the main scanning direction. An interval in the sub-scanning direction of the plural light beams is adjusted by tilting the optical element having the negative refractive power on an axis along the main scanning direction.