Embedded Encoder Linear Motor for Compact Voice Coil Stages
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Solution Overview
Problem
Conventional linear motors with conventional linear encoders increase the size and cost of voice coil stages due to the additional space and higher cost of the encoder, which is typically four to ten times greater than the motor.
Innovation Solution
Integration of a magnetic assembly and a coil assembly with an encoder strip and reader, where the encoder strip is attached to one assembly and the reader to the other, allowing for linear displacement and position sensing without the need for a separate encoder unit, thus reducing the overall size and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional linear encoder is attached to the side of the linear carriage system, then position sensing functionality is achieved, but the overall size of the voice coil stage increases
Solution Approach 1:
The encoder reader is integrated directly into the magnetic assembly, merging the encoder functionality with the existing motor structure. This eliminates the need for a separate encoder unit attached to the side of the linear carriage system, thereby reducing the overall footprint while maintaining position sensing capability
Solution Approach 2:
The magnetic assembly serves dual functions: it provides the magnetic field necessary for motor operation and simultaneously houses the encoder reader for position sensing. This multi-functionality reduces the number of separate components needed, decreasing the stage footprint
2Measurement precision
If a conventional linear encoder is used with the linear motor, then position sensing is provided, but the cost increases significantly
Solution Approach 1:
By integrating the encoder reader into the magnetic assembly, the patent eliminates the need for a separate, expensive encoder unit. The encoder reader can utilize existing components and structures within the motor assembly, significantly reducing the overall cost of the position sensing system
Solution Approach 2:
The magnetic assembly serves itself by housing the encoder reader within its own structure. This self-integration eliminates the need for additional encoder components and reduces dependency on external, high-cost encoder units, thereby lowering manufacturing costs
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 solution results in a smaller footprint and lower cost voice coil stage with integrated encoder functionality, maintaining the efficiency of linear displacement and position sensing without the need for a separate encoder unit.
Implementation Method 1
When current is applied to the coil 106, the coil assembly 104 will be linearly displaced with respect to the permanent magnet 102 depending on the polarity of the current flow
Implementation Method 2
an encoder reader attached to the other one of the magnetic assembly and the coil assembly to read the encoder strip during the linear displacement
Data Source
AI summary
A linear motor includes a magnetic assembly and a coil assembly having at least one coil positioned to magnetically engage the magnetic assembly for linear displacement between the magnetic assembly and the coil assembly. The linear motor further includes an encoder strip attached to one of the magnetic assembly and the coil assembly and an encoder reader attached to the other one of the magnetic assembly and the coil assembly to read the encoder strip during the linear displacement between the magnetic assembly and the coil assembly.