Electromagnetic Encoder Phase-Displaced Receiving Coils Offset Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional electromagnetic encoders face challenges in achieving strong signal strength with a small scale width and are weak in the pitching direction, due to the requirement of multiple lines of scale coils which increase encoder width and reduce signal strength.
Innovation Solution
The electromagnetic encoder features multiple sets of receiving coils along the measuring direction, with one set displaced by a ½ phase relative to the other, and multiple tracks with different scale pitches to enhance signal strength and reduce encoder width, allowing for a compact design and improved pitching direction variation resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple lines of scale coils are provided in the scale width direction, then offsets are reduced, but the encoder width increases and signal strength decreases
Solution Approach 1:
The patent transitions from arranging receiving coils in the scale width direction (horizontal dimension) to arranging them in the measuring direction (longitudinal dimension). This dimensional change allows offset reduction through phase-displaced coil pairs while maintaining a compact encoder width, directly resolving the contradiction between offset reduction and encoder size.
2Measurement precision
If multiple lines of scale coils are provided in the scale width direction, then offsets are reduced, but signal strength decreases due to longer wiring and impedance
Solution Approach 1:
By reorienting the receiving coil arrangement from the width direction to the measuring direction, the patent reduces coil wire length and impedance, thereby maintaining strong signal strength while achieving offset reduction through the phase-displaced coil configuration.
3Power
If scale coils are arranged with ½ phase displacement symmetrically, then signal strength is improved, but encoder width increases and pitching direction stability decreases
Solution Approach 1:
The patent employs asymmetric arrangement of receiving coils along the measuring direction with ½ phase displacement, rather than symmetric arrangement in the width direction. This asymmetric longitudinal arrangement maintains pitching direction stability while achieving the desired signal strength through optimized coil positioning and phase relationships.
4Area of stationary object
If encoder width is reduced, then compact design is achieved, but offset reduction capability is compromised
Solution Approach 1:
The patent achieves offset reduction within a compact encoder width by relocating the receiving coils from the width direction to the measuring direction. The phase-displaced coil pairs are arranged longitudinally, enabling offset cancellation without increasing encoder width, thus resolving this contradiction.
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 configuration results in a highly accurate and low-cost encoder with increased signal strength, reduced encoder size, and enhanced pitching direction stability, while maintaining strength in the yaw direction.
Implementation Method 1
a relative movement amount between the scale and the grid is detected based on variation in magnetic flux detected by the receiving coils via the scale coils at the time of exciting the transmitting coil
Data Source
Figure 1
Figure 2
Figure 3
AI summary
According to the present invention, an electromagnetic encoder includes a number of scale coils arranged on a scale along a measuring direction; and transmitting coils and receiving coils arranged on a grid to be movable relative to the scale in the measuring direction, in which a relative movement amount between the scale and the grid is detected based on variation in magnetic flux detected by the receiving coils via the scale coils at the time of exciting the transmitting coils, and the receiving coils are provided in the measuring direction to be a plurality of sets, one of the sets of the receiving coils being displaced by a ½ phase of a scale pitch relative to the other set of the receiving coils.