April 4, 2019
Magnetic sensors have been a staple for many years in various applications. They convert magnetic or magnetically encoded information into electrical signals for processing by electronic circuits.
In automotive systems alone they’ve been used for the sensing of position, distance and speed. For example, the position of the car seats and seat belts for air-bag control or wheel speed detection for the anti-lock braking system (ABS).
Hall-effect sensors in particular have been used for applications in detecting speed, position, and direction of travel for a target. But the newer kids on the block - Anisotropic Magnetoresistance (AMR) Sensors - are giving them a run for the money.
- Have higher sensitivity than Hall Effect sensors
- Are triggered by either a north or south pole (omnipolar sensing)
- Have increased resolution when using a ring magnet with the same number of poles as Hall Effect sensors
- Have the same resolution as Hall Effect sensors with a much larger air gap, even with a reduced number of poles
On the other hand, Hall-effect sensors have a proven track record in applications requiring tighter operating characteristics. And for applications requiring flexibility, external circuitry has allowed it to operate outside perceived parameters.
Both sensor types continue to offer non-contact, wear free operation, low maintenance cost, robust design, and immunity to vibration, dust, and water.
So … which do you choose for your application? Maybe taking a look at the individual technologies will shed some light.
There may not be a clear winner for your application. In that case, you win either way. Hall-effect sensors have been around for a long time. They’ve been custom fit with additional circuitry to overcome many perceived limitations. If your application fits that bill, you may want to consider sticking with what works.
Also remember that inherent Hall-effect Sensor limitations may be just what the sensor doctor ordered for your application. If you need a sensor with a small detection range and presentation area, trying to apply AMR Sensors would simply require additional circuitry and processing.
The good news is that more players mean more opportunities to apply a solution directly, or with just minor modifications. Happy sensing!