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Over 100 years ago, the Hall effect was identified. However, it is only within the last three decades that practical uses of this effect have been developed. Some of its first applications include use in microwave sensors in the 1950s and solid-state keyboards in the 1960s. Since the 1970s, Hall effect sensing devices have found their way into a wide range of industrial and consumer products, such as sewing machines, automobiles, machining tools, medical equipment, and computers.
Before examining the five key industrial applications of Hall effect sensors, it is necessary to define them, their function, and their various classifications.
What Is a Hall Effect Sensor?
Hall effect sensors are magnetic components that convert magnetically encoded information—such as position, distance, and speed—so that electronic circuits can process it. They are generally classified based on their manner of output or means of operation.
Separating Hall effect sensors by voltage output results in two sensor classifications: digital sensors and analog sensors.
Digital Output Hall Effect Sensors
Digital output Hall effect sensors are primarily used in magnetic switch applications to provide a digital voltage output. In this way, they provide an ON or OFF input signal to the system.
The primary distinction of a digital output Hall effect sensor is its means of controlling voltage output. Instead of the power supply providing the saturation limits, digital output sensors have a Schmidt-trigger with built-in hysteresis connected to the op-amp. This switch turns the sensor output off whenever magnetic flux exceeds its pre-set limits and back on when flux stabilizes.
Analog (or Linear) Output Hall Effect Sensors
An analog type sensor provides a continuous voltage output that increases when a magnetic field is stronger and decreases when it is weaker. Thus, the output voltage or amplification of an analog Hall effect sensor is directly proportional to the intensity of the magnetic flux passing through it.
In addition to classifying them by output, Hall effect sensors can be separated into categories based on the manner of operation, which includes:
Bipolar Hall Effect Sensors
This is a type of digital sensor, which operates using either positive or negative magnetic fields. Either the positive or negative magnetic field of the magnet activates the sensor. In this configuration, a switch using a bipolar Hall effect sensor is triggered in much the same way as a traditional Reed switch. However, the Hall effect switch has the added advantage of having no mechanical contacts, making it more durable in rugged environments.
Unipolar Hall Effect Sensors
In contrast to a bi-polar sensor, this type of digital sensor is triggered only by one pole (either North or South) of the magnet. Using a unipolar Hall effect sensor in a switch allows the set up to be more particular and only activate when exposed to a specific magnetic pole.
Direct Angle and Vertical Angle Hall Effect Sensors
More advanced Hall effect sensors focus on components of the magnetic field other than the poles. For example, direct angle sensors measure the sine and cosine measurements of the magnetic field, while vertical angle sensors analyze the components of the magnetic field that are parallel—rather than perpendicular—to the plane of the chip.
Five Key Applications of Hall Effect Sensors
Hall effect sensors find use in a broad range of applications across five major industries, which are:
Automotive and Automotive Safety
The automotive and automotive safety industries use both digital and analog Hall effect sensors in a variety of applications.
Examples of digital Hall effect sensor applications in the automotive industry include:
- Sensing seat and safety belt position for air-bag control
- Sensing the angular position of the crankshaft to adjust the firing angle for spark plugs
Some examples of the use of analog type sensors include:
- Monitoring and controlling wheel speeds in anti-lock braking systems (ABS)
- Regulating voltage in electrical systems
Appliances and Consumer Goods
The appliance and consumer goods industries integrate various types of Hall effect sensors in numerous product designs. For example:
- Digital unipolar sensors help washing machines maintain their balance during wash cycles.
- Analog sensors serve as availability sensors for power supplies, motor control indicators and shut-offs on power tools, and paper feed sensors in copier machines.
Digital Hall effects sensors are commonly used for monitoring flow rate and valve position for manufacturing, water supply and treatment, and oil and gas process operations. In fluid monitoring applications, analog Hall effect sensors are also used to detect diaphragm pressure levels in diaphragm pressure gauges.
In building automation operations, contractors and subcontractors integrate both digital and analog Hall effect sensors.
Digital, proximity-sensing devices are often used in the design of:
- Automatic toilet flushing mechanism
- Automatic sinks
- Automatic hand dryers
- Building and door security systems
Analog sensors are used for:
- Motion sensing lighting
- Motion sensing cameras
This is another area where both analog and digital Hall effect sensors continue to grow in popularity.
Applications for digital sensors include:
- Motor control devices
- Timing mechanisms in photography equipment
Applications for analog sensors include:
- Disk drives
- Power supply protectors
Contact MagneLink Today
As outlined above, Hall effect sensors—both analog and digital—find application in a broad range of devices, equipment, and systems across a variety of industries.
At MagneLink, we develop and manufacture high-quality magnetic switches, including switches that employ Hall effect sensors. To learn more about our Hall switches and their applications, contact us today.