Inductance Encoder for 2D Positioning
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Solution Overview
Problem
Existing driving mechanisms require bulky and expensive optical encoders for two-dimensional positioning, and inductance-type sensors can only detect one-dimensional motion, while conventional motors need separate coils and magnets for rotary and linear motions, increasing component count and cost.
Innovation Solution
A compact inductance-type encoder that detects both rotary and linear displacement using a single set of coils and magnets, allowing for closed-loop control of a motor's position in two dimensions with a slotted resolver and multiple-phase coils, enabling independent production of linear and rotary motions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical encoders are used for two-dimensional positioning, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces the optical encoder system with an inductance-type sensor system that uses electromagnetic induction instead of optical fields. The inductance-type encoder comprises a scale with conductive patterns and sensing coils that detect position through electromagnetic coupling, eliminating the need for optical components such as LEDs, lenses, and photodetectors. This substitution maintains measurement precision while significantly reducing device complexity and cost.
2Measurement precision
If optical encoders are used for two-dimensional positioning, then measurement precision is improved, but the area occupied increases
Solution Approach 1:
The inductance-type encoder uses electromagnetic fields instead of optical fields, allowing for a more compact design. The sensing coils and conductive patterns can be arranged in a compact configuration that occupies less space than the optical components required for similar precision. The electromagnetic coupling between the scale and sensing coils occurs through a small air gap, reducing the overall area required for installation.
3Device complexity
If inductance-type sensors are used for position detection, then device complexity is reduced, but measurement precision in two dimensions deteriorates
Solution Approach 1:
The inductance-type encoder scale is divided into multiple conductive pattern regions, each corresponding to a specific angular position. The scale comprises a plurality of conductive patterns arranged circumferentially, with each pattern generating a distinct inductance signal when excited. By segmenting the scale into multiple functional zones and using multiple sensing coils, the system can simultaneously detect both angular and linear positions with high precision, overcoming the limitation of conventional single-function inductance sensors.
4Reliability
If separate coils and magnets are used for rotary and linear motions, then reliability is improved, but device complexity and cost increase
Solution Approach 1:
The patent combines the rotary and linear drive functions into a single integrated motor structure. The motor comprises a stator with wound coils and a rotor with permanent magnets arranged such that the same electromagnetic interaction produces both rotational torque and linear force. The rotor is coupled to a lead screw or similar mechanism that converts rotational motion into linear motion, allowing one motor to replace what would traditionally require two separate motors, thereby reducing component count while maintaining reliability through unified control.
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 provides accurate, cost-effective, and space-efficient two-dimensional positioning and motion control, reducing component count and cost by using a single set of coils and magnets, and enabling simultaneous monitoring and control of linear and rotary motions.
Implementation Method 1
an inductance-type encoder operative to determine both linear and rotary displacement of the movable housing
Implementation Method 2
a driving motor which is operative to drive the movable housing to move linearly as well as to rotate relative to the fixed housing
Data Source
AI summary
A driving mechanism comprises a fixed housing, a movable housing on which an object to be driven is mounted and a driving motor which is operative to drive the movable housing to move linearly as well as to rotate relative to the fixed housing. An inductance-type encoder determines both linear and rotary displacement of the movable housing relative to the fixed housing, whereby to provide closed-loop control of the position of the object in both linear and rotary directions.