Recommended placement of magnets and TMR angle sensors
There are two main methods of arranging magnets and TMR angle sensors: On-axis (axial-end and shaft-end) and off-axis (extra-axial detection and outer ring detection), and good angular accuracy can be achieved with both arrangements.
In most cases, we recommend that the on-axis placement be considered first. If there are any constraints, the off-axis placement is considered.
On-axis placement
An arrangement that can detect the angle using a two-pole magnet placed at the end of the shaft with the sensor placed on the front.
- Advantages
- - The core has low magnetic field positional reliance, and it is easy to obtain high precision
- - The structure is simple, contributing to lower BOM and development man-hours and lower costs
- Disadvantages
- - Cannot be used if there is no space on the end of the shaft
Off-axis placement
The angle can be detected by placing a TMR angle sensor next to the shaft.
- Advantages
- - The sensor and magnet can be placed in the middle of the shaft in addition to at the end of the shaft, providing a higher degree of freedom regarding sensor placement
- Disadvantages
- - Since a multi-pole magnet is used, it is difficult to obtain high accuracy compared to on-axis due to the influence of magnetization accuracy and magnetic field
- - Magnetic field positional reliance is high, so high assembly accuracy is needed
- - When precision equivalent to that of on-axis placement is required, the compensation processing load increases
＞＞Examples of recommended placement of TMR sensors and magnets are presented on the following page
