Polygon Mirror Layout for Low-Distortion Multi-Area Scanning
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional polygon mirrors face challenges in achieving long scanning lines with low distortion, as increasing the number of sides to reduce distortion is hindered by the need for a larger light deflection angular range, and scanning near the vertex of the polygon can lead to instability and inefficiency.
Innovation Solution
A polygon mirror design that switches the emission position discontinuously as it rotates, allowing for flexible scanning of multiple areas with reduced distortion by guiding light to different scanning areas using a combination of first and second light reflection units, ensuring a constant light path length and scanning speed, and optimizing the rotation phase to minimize unusable ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the number of sides of the polygon mirror is increased to reduce scanning distortion, then the scanning quality is improved, but the light deflection angular range becomes too large to be practical
Solution Approach 1:
The patent divides the scanning function into multiple independent light reflection units, each handling a specific angular range. Instead of using one large polygon mirror with many sides, the system segments the scanning task across multiple units with fewer sides each, thereby reducing individual mirror sizes while maintaining overall scanning coverage and low distortion.
Solution Approach 2:
The patent introduces a new dimension by arranging multiple light reflection units in different spatial positions and orientations. Rather than increasing the number of sides in a single mirror plane, the system distributes scanning functions across multiple mirrors positioned at different locations, effectively using spatial arrangement to achieve the angular range needed for long scanning lines.
2Area of stationary object
If the polygon mirror scans near the vertex to extend the scanning line, then the scanning area is increased, but the scanning distortion increases and stability decreases
Solution Approach 1:
By segmenting the scanning area into multiple zones handled by different light reflection units, each unit operates within an optimized angular range that avoids the vertex region. This segmentation allows the system to cover a large total scanning area while each individual mirror maintains low distortion by not scanning near its vertex.
Solution Approach 2:
Each light reflection unit is designed with specific local characteristics optimized for its designated scanning zone. The mirrors are positioned and oriented so that their active scanning regions operate in the low-distortion central portions of their deflection ranges, applying different operational qualities to different parts of the overall scanning system.
3Speed
If the polygon mirror rotates continuously to maintain scanning, then the scanning speed is maintained, but the unusable range increases when the rotation phase hits the vertex
Solution Approach 1:
The patent segments the rotational scanning into multiple overlapping zones handled by different light reflection units. When one mirror approaches its unusable vertex region, another unit takes over, allowing continuous scanning without interruption. This segmentation eliminates the loss of time associated with single-mirror vertex passages.
Solution Approach 2:
The system is designed to maintain continuous useful scanning action by coordinating multiple light reflection units. As one unit exits its optimal scanning range or encounters its vertex, another unit is already positioned to take over, ensuring that the scanning action continues without interruption or loss of time.
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
Enables high-speed switching of scanning ranges with low distortion across multiple areas, allowing for efficient long-distance straight scanning while minimizing the need to shut off the laser beam, thus improving scanning quality and reducing the polygon mirror's size.
Implementation Method 1
Light incident in a predetermined direction is reflected by a reflection surface of each side of a regular polygon of the polygon mirror which rotates. Accordingly, the polygon mirror emits the light while the polygon mirror rotates.
Implementation Method 2
The light reflection means reflects the light emitted from the light projection means by a plurality of reflective sections. The light reflection means leads the light to an arbitrary irradiated point on a predetermined scanning line.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A polygon mirror rotates around a rotational axis. A first reflection surface and a second reflection surface are placed on two or more of a plurality of sides of the polygon mirror, respectively. The first reflection surface is formed in a planar shape inclined to a plane perpendicular to the rotational axis. The second reflection surface is formed in a planar shape inclined with respect to a plane perpendicular to the rotational axis. Light which entered into the polygon mirror is reflected by the first reflection surface and then by the second reflection surface. Among the plurality of the sides, at least one of a direction in which the first reflection surface is inclined with respect to a plane perpendicular to the rotational axis and a distance in the direction of the rotational axis between the first reflection surface and the second reflection surface is different.