Scanner Motor Rotor Case Protrusions for Mirror Stability
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Solution Overview
Problem
Conventional scanner motors face issues with the stability and coupling of polygon mirrors due to low coupling force and deformation under high-speed rotation, leading to instability and increased manufacturing costs.
Innovation Solution
A scanner motor design featuring a rotor case with semicircular protrusions for stable support and concave parts to absorb stress, integrated with a magnetic material and laser welding for high-strength coupling, eliminating the need for a machined housing shaft.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a spring is used to couple the polygon mirror to the housing shaft, then the assembly is simple, but the coupling force is low and the polygon mirror becomes separable under strong impact
Solution Approach 1:
The housing shaft is segmented into multiple protrusions (first, second, and third protrusions) that distribute the coupling force across multiple contact points with the polygon mirror, rather than relying on a single spring contact point. This segmentation increases the overall coupling strength while maintaining structural simplicity
Solution Approach 2:
The functions of support, coupling, and stress distribution are merged into the integrated housing shaft structure with multiple protrusions, eliminating the need for separate coupling mechanisms while achieving both simplicity and high coupling force
2Device complexity
If the housing shaft is used to support the polygon mirror, then the structure is simple, but the flatness and rotating center stability deteriorate under high-speed rotation
Solution Approach 1:
Specific regions of the housing shaft are designed with different geometric properties - the protrusions provide localized support points that maintain flatness, while the overall shaft structure maintains rotational stability. The concave part introduces localized stress absorption capability without compromising overall structural simplicity
Solution Approach 2:
Instead of trying to make the housing shaft perfectly rigid and precise throughout, the design inverts the approach by introducing a concave part that deliberately allows controlled deformation in specific regions to absorb stress, while maintaining precision at the critical support points where protrusions contact the polygon mirror
3Reliability
If the spring is pressed against the polygon mirror, then the mirror is secured, but the spring deforms under floating force during high-speed rotation impairing balance
Solution Approach 1:
The spring component is extracted and removed from the design. Instead of using elastic deformation of a spring to secure the polygon mirror, the housing shaft directly provides securing force through its rigid protrusions, eliminating the source of deformation and imbalance
Solution Approach 2:
The housing shaft serves multiple functions simultaneously - it provides structural support, coupling force, stress absorption, and balancing - without requiring additional components like springs. The structure serves itself by integrating all necessary functions into the shaft's geometry
4Manufacturing precision
If machining is used to manufacture the housing shaft, then the flatness can be maintained, but the manufacturing cost increases
Solution Approach 1:
The mechanical machining process is replaced with mold injection molding for manufacturing the housing shaft. The complex geometric features (protrusions and concave parts) are integrated into the mold design, allowing high-precision features to be formed directly during molding without subsequent machining operations, thereby reducing cost while maintaining precision
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 ensures stable rotation and flatness of the polygon mirror, reduces deformation, and lowers manufacturing costs by using a pressed rotor case and eliminating the need for a machined housing shaft.
Implementation Method 1
a stator (not shown) which is mounted to the outer circumference of a bearing holder (not shown) and is thus subjected to external power
Implementation Method 2
a spring 12 which is used to couple the polygon minor 11 to the housing shaft 13
Data Source
AI summary
Disclosed herein is a scanner motor. The motor includes a base plate supporting the scanner motor, with a circuit board mounted on the base plate. A rotating shaft supports the scanner motor vertically in such a way that the scanner motor is rotatable. A bearing is rotatably fitted over the rotating shaft. A bearing holder holds the bearing. A stator is mounted to an outer circumference of the bearing holder to generate electricity. A rotor case is rotatably fitted over the rotating shaft so as to mount a polygon mirror. Three semicircular protrusions protrude from an upper portion of the rotor case at regular intervals to stably support the polygon minor. A concave part is formed between the protrusions to absorb external stress.