Galvanometric Scanner Torque Constant Equalization
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Solution Overview
Problem
Existing galvanometric scanners face challenges in maintaining a uniform torque constant across different rotation angles due to varying magnetic flux density, leading to reduced positioning accuracy and increased positioning time.
Innovation Solution
The scanner design incorporates radially depressed grooves on the permanent magnet's outer circumference, with varying groove lengths and widths to match the rotation angle, and additional coils to optimize torque constant uniformity, ensuring consistent magnetic flux distribution and reduced torque variation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the outer diameter of permanent magnets is set to be substantially constant, then the structure is simple, but the torque constant varies significantly (reduced by about 10%) when the rotation angle changes by 15 degrees
Solution Approach 1:
The patent applies local quality by forming radially depressed grooves in specific regions of the permanent magnet's outer circumferential surface. These grooves are not uniformly distributed but are strategically positioned to modify magnetic flux density in localized areas, thereby compensating for torque constant variations at different rotation angles while maintaining overall structural simplicity.
Solution Approach 2:
The patent changes the geometric parameters of the permanent magnet by introducing grooves with specific dimensions (depth, width, and circumferential length). These parameter modifications alter the magnetic flux distribution, enabling the torque constant to be equalized across different rotation angles without fundamentally changing the motor's structure.
2Manufacturing precision
If grooves are formed in the permanent magnet to equalize torque constant, then torque uniformity improves, but manufacturing complexity increases
Solution Approach 1:
The groove dimensions (depth, width, and circumferential length) are optimized to achieve torque constant equalization. By carefully controlling these parameters, the patent achieves the desired torque uniformity while keeping the manufacturing process relatively simple, as groove formation is a standard machining operation.
Solution Approach 2:
The grooves are designed with specific local characteristics (different circumferential lengths corresponding to different poles) to achieve torque equalization. This localized modification approach allows for precise control of magnetic flux distribution without requiring complex overall structural changes.
3Manufacturing precision
If the circumferential length of grooves is precisely matched to coil positions (within ±10 degrees), then torque constant equalization is optimized, but manufacturing precision requirements increase
Solution Approach 1:
The circumferential length of each groove is precisely adjusted based on the corresponding coil's position and width. This parameter optimization ensures that the modified magnetic flux density distribution aligns with the coil locations, achieving torque constant equalization. The ±10 degree tolerance provides a practical balance between precision and manufacturability.
Solution Approach 2:
The groove design incorporates feedback from the coil positions and the desired torque characteristics. By matching the groove circumferential lengths to the coil configurations, the patent creates a self-correcting system where the magnetic flux distribution automatically compensates for torque variations, reducing positioning time and improving accuracy.
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 design significantly reduces torque constant variation with rotation angle, enhancing positioning accuracy and reducing positioning time by maintaining a consistent torque constant across the scanner's range.
Implementation Method 1
magnetic flux density substantially describes a parabola in which the magnetic flux density is maximized in a circumferential center position of each permanent magnet and reduced toward opposite circumferential end portions of the permanent magnet
Implementation Method 2
coils disposed in the inner circumferential side of the yoke
Data Source
AI summary
A scanner has a rotor, and a stator disposed in the outside of the rotor. The rotor includes a shaft, and a permanent magnet mounted on the outer circumferential side of the shaft. The stator includes a casing, a yoke held in the inner circumferential side of the casing, and coils disposed in the inner circumferential side of the yoke. The permanent magnet of the rotor has radially depressed grooves formed in its outer circumferential portion. The torque constant of the scanner is circumferentially equalized by the grooves.