Combined Rotary Encoder With Magnetic Reference and High Resolution
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Solution Overview
Problem
Existing rotary encoders with diametrically polarized magnets have lower resolution and cannot be miniaturized effectively, limiting their application in compact devices.
Innovation Solution
A combined rotary encoder design integrating a primary rotary encoder with a secondary rotary encoder, where the diametrically polarized permanent magnet is positioned within the primary scale, and the secondary magnetic sensor is integrated on the same sensor holder, enabling high-resolution output signals with a unique reference pulse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a diametrically polarized permanent magnet is used as the scale, then the encoder construction can be simplified and miniaturized, but the resolution of position information decreases to only 4,096 positions per full rotation
Solution Approach 1:
The patent combines two encoder systems into a single integrated encoder: a first encoder with a periodic pattern scale providing high-resolution relative position information, and a second encoder with a diametrically polarized permanent magnet providing absolute position information. The sensor integrates both optical sensing elements for the periodic pattern and magnetic sensing elements for the permanent magnet, merging two previously separate systems into one unified device that delivers both high resolution and miniaturization benefits.
2Measurement precision
If multiple periods on the scale are used to increase resolution, then position precision improves, but the encoder construction becomes more complex and larger
Solution Approach 1:
The patent segments the encoder functionality into two distinct parts: a first scale with multiple periods (e.g., 25 periods) for high-resolution relative position measurement, and a second diametrically polarized permanent magnet for absolute position reference. This segmentation allows each component to be optimized independently - the periodic pattern provides fine resolution while the permanent magnet provides a compact absolute reference, avoiding the need for a single complex scale with excessive periods.
3Reliability
If a diametrically polarized permanent magnet is used, then the encoder can provide absolute position information, but the number of distinctive positions is limited to 4,096 per full rotation
Solution Approach 1:
The patent makes the sensor multi-functional by integrating both optical sensing elements for detecting the periodic pattern and magnetic sensing elements for detecting the permanent magnet's field. This allows a single sensor assembly to perform two functions: measuring high-resolution relative position through the periodic pattern and determining absolute position through the permanent magnet, eliminating the need for separate sensors and making the system universally capable of both measurement modes.
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 combined rotary encoder achieves high-resolution position information with a miniaturized construction, allowing for precise absolute position determination within a single rotation.
Implementation Method 1
a primary sensor (3) having primary sensing elements (3a) adapted to detect the periodic pattern on the primary scale (2) and generating a periodic primary sensor signal
Implementation Method 2
a secondary magnetic sensor (5) having secondary magnetic sensing elements (5a) and generating a secondary sensor signal
Data Source
Figure 1~2
Figure 3~4
AI summary
A combined rotary encoder of the present invention consists of a combination of components of two known rotary encoders: components of a primary rotary encoder and components of a secondary rotary encoder. The primary rotary encoder comprises a primary scale configured as a ring provided with a track with a periodic pattern, and a primary sensor provided primary sensing elements. The secondary rotary encoder comprises a secondary scale configured as a diametrically polarized permanent magnet, and a secondary magnetic sensor provided with secondary magnetic sensing elements. The combined rotary encoder provides high resolution of the rotation position in the output signal, which is achieved by the primary scale and the primary sensor and a unique reference pulse in the output signal which is provided by the secondary scale and the secondary magnetic sensor.