Polygon Mirror Scanner Motor With Dynamic Pressure Bearing
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Solution Overview
Problem
Conventional polygon mirror scanner motors face challenges in reducing size and thickness while maintaining high precision and preventing plane tilting, and they experience vibration and noise issues at high speeds due to one-side support structures and grinding motion, which shortens bearing life and complicates mirror surface formation.
Innovation Solution
A polygon mirror scanner motor design featuring a shaft fixed type fluid bearing with herringbone grooves and laser welding for precise fixation to an iron plate circuit board, creating a dynamic pressure bearing that supports the rotor and reduces vibration and noise, allowing for high-speed operation with improved bearing life and precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a one-side support structure with dynamic pressure bearing is used, then the motor can be made smaller and thinner, but vibration and noise increase at high speeds due to grinding motion
Solution Approach 1:
The patent divides the single dynamic pressure bearing into two separate dynamic pressure bearings, one supporting each end of the rotor. This segmentation of the support function eliminates the grinding motion that occurs in one-side support structures, thereby reducing vibration and noise at high speeds while maintaining the compact motor design.
Solution Approach 2:
Instead of using a conventional one-side support structure where the rotor is supported at only one end, the patent inverts the approach by implementing two-side support with dynamic pressure bearings at both ends. This inversion of the support configuration eliminates the harmful grinding motion while preserving the space-saving benefits.
2Manufacturing precision
If bearing precision is increased to prevent plane tilting of the polygon mirror, then mounting precision must be maintained at very high levels, complicating manufacturing
Solution Approach 1:
The dynamic pressure bearings automatically self-align and compensate for minor mounting inaccuracies through their hydrodynamic pressure generation mechanism. This self-service capability allows the bearings to maintain high rotational precision and prevent polygon mirror plane tilting without requiring extremely tight mounting tolerances, thereby simplifying manufacturing while ensuring high precision operation.
3Productivity
If the motor operates at high speed, then productivity increases, but bearing life shortens due to grinding motion and increased wear
Solution Approach 1:
By segmenting the single bearing support into two separate dynamic pressure bearings, the patent eliminates the grinding motion that causes accelerated wear. This allows the motor to operate at high speeds for extended periods without bearing degradation, thereby extending bearing life while maintaining high productivity through sustained high-speed operation.
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
The design achieves a compact, low-cost, high-reliability motor with reduced vibration and noise, enabling high-speed operation and precise mirror surface formation, while ensuring long bearing life and maintaining high mounting precision.
Implementation Method 1
a dynamic pressure bearing which has a dynamic pressure groove, for generating a dynamic pressure in the radial direction, in either one of the circular tube part of the rotor boss and the shaft
Implementation Method 2
bearing 420 composes a fluid bearing
Implementation Method 3
The shaft is fixed to the through-hole by laser welding
Data Source
AI summary
The rotor of this polygon mirror scanner motor is composed of a rotor magnet provided in the inner wall of a rotor frame, a rotor boss having a circular tube part and provided in the rotor frame, and a polygon mirror mounted on the rotor boss. The stator is composed of a stator core formed by laminating magnetic members and disposed oppositely to the rotor magnet, a stator coil wound in the stator core, and an iron plate circuit board having a through-hole. A dynamic pressure bearing is composed by forming a dynamic pressure groove in either one of the shaft fixed in the through-hole by laser welding, and the circular tube part of the rotor boss, and the circular tube part of the rotor boss is supported by the shaft.