Application Catalog

102 - Magnetic Field Analysis of a Magnetic Sensor <ST>

Overview

Magnetic sensors are used as highly durable and reliable open/close switches to meet the current demands for a variety of electrical equipment and home appliances.
An open/close switch combines a detection component and magnet to detect a position using the magnetic flux variations when the information is accessed by the detection component.
Selecting the appropriate detection component and magnet as well as evaluating the be arrangement is necessary during the design stage to obtain highly sensitive and accurate location detection.
This example presents the use of a magnetic field analysis to evaluate the magnetic flux density distribtion in both the horizontal and perpendicular directions of a magnet.

Magnetic Flux Density Distribution

The magnetic flux density distribution of the Z component produced around the magnet is indicated in Fig. 1. The magnetic flux density for the Z component versus horizontal distance is indicated in Fig. 2. The magnetic flux density of the θ component versus rotation angle is indicated in Fig. 3. The positive values indicate positive direction of the Z-axis, the negative values indicate negative direction of the Z-axis. The magnetizing direction of the magnet has negative values on the Z-axis in the perpendicular direction, and has positive values on the Z-axis in the horizontal direction, as indicated in Fig. 1 For this reason, if the IC is moved in a horizontal direction, the magnetic flux density that has a negative value for its initial position weakens toward a positive value when it is moved away from the magnet, as indicated in Fig. 2. The direction of the magnetic flux density changes minimally for a rotation angle range of 15 degrees, and the magnetic flux density in the Z-component direction decreases when the detection component is moved away from the magnet, as indicated in Fig. 3. The detailed evaluation of the magnetic flux density distribution and detection range of the magnetic flux density can be estimated from these results.
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Updated: 2011-01-17

Application Catalog