The working principle of a Hall sensor is as follows: A Hall semiconductor plate is placed in a magnetic field, and a constant current I flows from A to B through the plate. Under the action of the Lorentz force, the electron flow of I is deflected to one side when passing through the Hall semiconductor, causing a potential difference to be generated in the plate along the CD direction, which is the so-called Hall voltage.
What is a Hall sensor?
A Hall sensor is a magnetic field sensor based on the Hall effect. According to the Hall effect, a component made of semiconductor material is called a Hall element. It has advantages such as sensitivity to magnetic fields, simple structure, small size, wide frequency response, large output voltage variation, and long service life. Therefore, it is widely used in measurement, automation, computer, and information technology fields.
What are the common types of Hall effect sensors?
1. Hall effect pressure sensor: One end of the sensing element, a spring plate, is fixed, while the other end is fitted with a Hall element. When the input pressure increases, the spring extends, causing the Hall element, which is in a constant gradient magnetic field, to displace accordingly. The magnitude of the voltage output from the Hall element reflects the pressure level.
2. Hall current sensor: An air gap is made in the magnetic core, and a linear Hall element is built in. After the device is powered on, the magnitude of the current flowing in the wire can be obtained from the Hall voltage output by it.
What are the application areas of Hall effect sensors?
1. Measurement applications: It can be used to measure magnetic fields, current, displacement, pressure, vibration, rotational speed, etc.
2. Communication field: It can be used in amplifiers, oscillators, phase-sensitive detectors, mixers, frequency dividers, and microwave power measurement, etc.
3. Automation Technology: Applicable to brushless DC motors, speed sensors, position sensors, automatic counting, proximity switches, etc. I. Introduction
The Hall effect is the most commonly used method for measuring magnetic fields, and Hall effect sensors have been widely used and applied in modern applications. For example, they are used in automobiles as wheel speed sensors and crankshaft or camshaft position sensors. They are also commonly used as switches, MEMS compasses, proximity sensors, and in other applications. Now let's look at how these sensors work, but first, let's define the Hall effect.
Table of contents
I. Introduction
II. What is the Hall effect?
III. What is a Hall effect sensor?
IV. How Hall effect sensors work
V. Types of Hall Effect Sensors
5.1 Threshold
5.2 Linear
VI. Applications of Hall Effect Sensors
6.1 Frontal inspection
6.2 Lateral Detection
VII. Applications of Hall Effect Sensors
7.1 Hall Effect Sensors in Rotation Applications
7.2 Hall Effect Sensors in Short-Range Applications
7.3 Application of proximity Hall effect sensors in robotics
8. How to test a Hall effect sensor
IX. Frequently Asked Questions
II. What is the Hall effect?
The Hall effect can be described as follows: If we have a conductive plate as shown in the figure and apply a current to it, charge carriers will flow in a straight line from one side to the other.
Now, if we apply a magnetic field near the plates, we can disrupt the straight flow of charge carriers under the influence of the Lorentz force. Electrons will deflect towards one side of the plates, while positive holes will deflect towards the other side. This means that if we now connect a multimeter to the other two sides, we can obtain a measurable voltage.
As mentioned earlier, the effect of obtaining a measurable voltage is known as the Hall effect, which was discovered by Edwin Hall in 1879.
III. What is a Hall effect sensor?
Hall effect sensors detect changes in magnetic field power. This type of sensor offers a wide range of possibilities for applications in robotic sensors.
They can be used in applications such as proximity, positioning, speed, and current sensing. They are commonly used on pneumatic cylinders to communicate the cylinder's position with a PLC or robot controller.
Automotive, personal electronics, and robotics are just a few industries that use Hall effect sensors. Depending on the application, they offer several advantages over other sensors.
They are completely enclosed because they operate in a magnetic field, making them less susceptible to damage from dirty or humid environments. They are less likely to wear out or tilt readings after a large number of cycles than mechanical systems.
Because Hall effect sensors can operate without physical contact, their reliability and lifespan are highly valuable in a wide range of applications. They offer higher repeatability and accuracy than mechanical units because they do not physically interfere with machinery or tools.
IV. How Hall effect sensors work
It's best to start by understanding the basics of the Hall effect to understand Hall effect sensors. When an electric current flows through a conductor in a magnetic field, electrons are pushed to one side of the conductor by the magnetic field.
The Hall effect can be used to measure the current in conductors composed of specific parameters. For example, the voltage across a flat metal conductor reveals the Hall effect more clearly than the voltage around the conductor.
When a magnetic field is applied to a flat plate, electrons moving on the conductor are forced to move to one side. Because the sum of the deflections can be calculated, this device has a wide range of applications.
The magnetic field strength of the Hall effect sensor is calculated using a flat conductor. When a magnet approaches the sensor, the sensor detects it and sends the information to the controller.
When a magnet approaches the sensor, the charge passing through the plates shifts to one side, creating a positive charge on one side and a negative charge on the other. Determining the voltage difference across the plates can be used to calculate the magnetic field strength or the sensor's proximity.
V. Types of Hall Effect Sensors
Hall effect sensors have two basic types:
5.1 Threshold
When the magnetic field strength reaches a certain amplitude and/or polarity, the threshold (also known as a digital or switch) generates a constant Hall voltage. Several different threshold device configurations exist, such as latching devices that turn on when a positive electric field strength reaches the threshold but turn off only when a negative electric field of the same strength reaches the threshold, devices that turn on only when a positive electric field reaches the threshold but turn off under other conditions, and devices that turn on when both positive and negative electric fields reach the threshold. Thresholds can also be programmed in some computers.
5.2 Linear
Linear (analog output sensor) generates a Hall voltage proportional to the strength of the surrounding magnetic field. The polarity of the voltage swing is determined by the direction of the surrounding magnetic field. Linear devices are more commonly used in music applications when expressive movements must be perceived as minute changes in position.
VI. Applications of Hall Effect Sensors
Hall effect sensors are driven by magnetic fields. In many applications, a single permanent magnet connected to a moving axis or device can control the device. There are many different forms of magnetically induced motion, including "head-up," "sideways," "push-pull," and "push-push." To ensure optimal sensitivity of the magnetic field lines and the configuration of the magnetic flux, the sensitivity of the magnetic field lines must always be in the correct position.
To ensure linearity, a high-field magnet that causes a significant change in magnetic field strength is also required. Several methods exist for detecting magnetic fields; the two most common sensing configurations using a single magnet are shown below: front detection and side detection are two types of detection.
