[muRata] Magnetic Pattern Recognition Sensors

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External Magnetic Noise Immunity Characteristic

Both the DC and AC motors that are used to transport target media may generate magnetic noise such as spike noise.
Since the sensor case is made of a non-magnetic material, it has no shielding effect.
Therefore, when a motor or CRT display is placed near the sensor, the magnetic shield, motor mounting direction, and distance between the sensor and noise source must be considered.
In such a case, you are recommended to use the BS05N1HG type, which provides excellent external magnetic noise immunity.

1. The sensor's built-in bias magnet will cause magnetic flux leakage.

* The sensor's sensitive range is examined by scanning an iron plate (SPC, t 0.2 mm x 5 mm) over the sensor's detecting surface.

External Magnetic Noise Immunity Characteristic

(1)	The magnetic flux density on the detecting surface is approx. 120 mT.
(2)	If other magnetic factors are present near the iron plate, the test conditions will change.
(3)	When the iron plate is moved, the sensor's insensitive distance is 15 mm or more. If designing a magnetic circuit with a magnetic plate placed near the sensor, please take care not to be influenced by the magnetic plate.

2. The influence of magnetic noise varies depending on the sensor mounting direction.

Magnetic source device
Induction motor (100 V, 50 Hz)
The output voltage resulting from the AC magnetic field generated by the motor is measured.

(1)	The sensor's detecting surface and lateral surface are both sensitive. It is effective to provide magnetic shielding for the sensor's lateral surface.

(2)	With a power supply frequency magnetic field immunity testing instrument conforming to IEC 61000-4-8, the sensor output is amplified for measurement. The HG type sensor is highly resistant to magnetic noise.

Magnetic field intensity of 100 A/m corresponds to free space induction of 0.125 mT.

The sensor circuit is a voltage division circuit using two elements. Noise that evenly affects these two elements is cancelled, and is not output from the sensor.
If an AC magnetic field of approx. 0.1 mT is present neat the sensor, the HG type is recommended.

The difference between the HF and HG types is the magnetic circuit of the sensor.

	Output voltage	Magnetic noise
HG type
HF type

Power supply frequency magnetic field immunity testing instrument conforming to IEC 61000-4-8

<Shield Room and Testing Instrument>	<Helmholtz Coil>

	The testing instruments include a current source (test generator), induction coil, and auxiliary testing/measuring devices. The testing magnetic field is obtained by the current flowing through the induction coil.