Polarization-Maintaining Rotary Encoder for Multi-Stage Angle Measurement
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Solution Overview
Problem
Current devices for measuring rotational angles in counters and multi-turn rotary encoders are complex and expensive due to the need for multiple independent angle sensors, collimated light sources, and precise optics, which are limited in range and accuracy, especially when measuring over multiple revolutions or large distances.
Innovation Solution
A device using at least one rotatable wheel with partial transparency and polarization-maintaining properties, where light is polarized by pole filters and received by polarization sensors, allowing measurement over multiple wheels without significant polarization change, enabling unambiguous angle measurement over 360° with reduced sensor complexity and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple independent angle sensors, collimated light sources, and precise optics are used for each counting wheel, then measurement precision is improved, but device complexity and manufacturing cost increase significantly
Solution Approach 1:
The patent combines multiple angle measurement functions into a single polarization sensor that can detect the rotational position of multiple counting wheels simultaneously. Instead of using separate sensors for each wheel, the system uses one sensor with polarizing filters that can distinguish signals from different wheels through polarization state analysis, thereby reducing system complexity while maintaining measurement precision
Solution Approach 2:
The polarization sensor serves multiple functions: it measures angular position, distinguishes between different counting wheels, and operates without requiring precise optical alignment. The single sensor performs what previously required multiple specialized sensors, making the system more versatile and easier to manufacture
2Length of stationary object
If conventional optical encoders are used with large distances between code disks and sensors, then measurement range is expanded, but signal accuracy deteriorates due to scattered light and adjustment complexity
Solution Approach 1:
The patent changes the optical parameter by using polarized light instead of conventional unpolarized light. This parameter change allows the light to maintain its directional properties over longer distances without scattering, enabling accurate measurement at larger distances between the code disks and sensor while preserving signal accuracy
Solution Approach 2:
The polarizing filters act as intermediaries that modify the light's properties to enable long-distance measurement. The polarized light serves as a mediator between the code disks and sensor, carrying positional information accurately over extended distances without the degradation that plagues conventional optical systems
3Area of moving object
If magnetic code disks are used with large diameters, then measurement range is increased, but magnetic field strength decreases making reliable measurement difficult
Solution Approach 1:
The patent replaces the magnetic field-based measurement system with an optical polarization-based system. Instead of detecting magnetic field changes from large-diameter code disks, the system uses polarized light interaction with polarization-maintaining materials on the disks, eliminating the inverse square law limitation of magnetic fields and enabling accurate measurement over larger areas
4Productivity
If electronic counting devices with power supply are used, then measurement functionality is improved, but operational reliability during power failures decreases
Solution Approach 1:
The polarization-based measurement system is designed to be self-service in terms of power requirements. The optical components and polarization sensors can operate passively or with minimal power, allowing the counting function to continue during power failures. The system serves itself by using inherent optical properties rather than requiring active electronic processing for basic measurement
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 solution simplifies the design and reduces costs by allowing measurement of rotational angles over multiple revolutions with higher accuracy and longer distances, eliminating the need for precise alignment and multiple sensors, and enabling mechanical operation without electrical energy.
Implementation Method 1
parts of the wheel being configured as pole filters, it being possible for light which exits the light source to be polarized by the pole filter and to be received by the polarization sensor
Implementation Method 2
the wheel being at least partially transparent and polarization-maintaining
Data Source
AI summary
Various embodiments relate to devices for measuring the state of devices and multi-stage rotary encoders as well as to associated sensors. In order to simplify the design of devices which can be read out electronically and multi-turn rotary encoders, according to some embodiments a device having at least one rotatable wheel, at least one light source and at least one polarization sensor is proposed, the wheel being at least partially transparent and polarization-maintaining, parts of the wheel being configured as pole filters, it being possible for light which exits the light source to be polarized by the pole filter and to be received by the polarization sensor.