What is an Proximity Sensor? Characteristics and principle of operation

What is an proximity sensors? – It may sound strange, but it’s actually very familiar, because they appear right in the phone you use every day. So what are proximity sensors and how do they work? Let’s explore the details with RX Tradex through this article.

1. What is a proximity sensor?

Proximity sensors (also known as Proximity Switches or PROX – Proximity Sensors) are sensors that react to an object approaching within a few millimeters. The proximity sensor is mainly used to determine the final location of the machine parts, and the output signal of the sensor will trigger another function of the machine. In particular, this type of sensor works well even in harsh environments.

Proximity sensors convert signals through the movement or appearance of objects into electrical signals. This process is carried out through three main detection systems: a system that uses eddy current in a metal object by electromagnetic induction, a system based on a change in capacitance when approaching the object to be detected, and a system that uses magnets and an additive switching mechanism.

2. Operating principle of proximity sensor

This type of sensor works on the principle of touch and reacts to changes in the surrounding environment. The principle of operation can vary according to the type of proximity sensor, they are usually divided into 3 main types: electromagnetic induction, mechanical induction, and optical induction.

The operation of each type of sensor is as follows:

• Electromagnetic induction: Electromagnetic induction-based proximity sensors work based on changes in the electromagnetic field to detect objects. This sensor generates an electromagnetic field around it, and as an object approaches, the electromagnetic field changes, resulting in a variation in the output voltage or current. Thereby, the sensor determines the presence and distance of the object.
• Optical Induction: Optical touch-based proximity sensors use the reflection or absorption of light to detect objects. The sensor emits a beam of light (infrared laser) and measures the amount of light reflected or absorbed when it touches an object. The change in reflected light helps the sensor to recognize the presence and distance of the object.
• Mechanical Induction: Mechanical proximity sensors work on the principle of mechanical change to detect the contact or presence of an object. This type of sensor can use mechanical factors such as compression or separation to activate the sensor. When the object is exposed or isolated, a change in pressure or position activates the sensor.

Information from all types of proximity sensors is sent to the electronic circuit for processing and giving results. Proximity sensors can detect the presence or distance of objects, and this information can be used to activate control systems, alarms, or change the operation of related devices.

3. Types of proximity sensors

There are 2 types of proximity sensors:

• Word touch

Shielded magnetic induction: In this type, the magnetic field is concentrated in front of the sensor, which minimizes disturbances from surrounding metals. However, the measurement distance is short.

Unshielded Sensor: An unshielded magnetic field around the sensor face, allowing the sensor to measure at a greater distance. However, this type is susceptible to interference by surrounding metals.

• Capacitive touch sensor

This sensor operates on the principle of electrostatic, detecting the change in capacitance between the sensor object and the sensor head. The capacitive touch type is capable of detecting all objects.

4. Effects of proximity sensors on phones

Benefits of Proximity Sensors on Phones

• Save battery, as the screen is one of the most energy-consuming components on a phone.
• It helps maintain a stable temperature, thereby extending the life of the device and ensuring the safety of users when using it.
• Prevents users from accidentally touching the end call button while talking on the phone.

5. Some other applications of proximity sensors in life

Currently, proximity sensors are widely used in many fields, especially in the manufacturing, automotive, and telephone industries,…

• Control the amount of metal.
• Monitor the liquid level in the tank.
• Detect objects such as Palette, Aluminum Ion,…
• Check the fracture condition of the drill bit.
• Track and count the number of die operations.

6. Notes when using the proximity sensor

When using proximity sensors, there are a few important factors to keep in mind to ensure performance and durability

• Range and distance: Understand the range and distance of sensor operation to ensure accurate operation.
• Operating Environment: Consider the effects of temperature, humidity, and other environmental factors on the sensor.
• Proper Installation: Make sure the sensor is positioned and at the correct angle to correctly detect and respond to changes in the environment.
• Periodic Testing: Periodic testing is required to maintain sensor stability and reliability.
• Supply Quality: Ensure a stable power supply so as not to affect the operation of the sensor.
• Select the right sensor type: Select the appropriate sensor for the specific application. There are different types of asymptotics based on the principle of operation and the nature of the object to be detected.
• Maintenance and cleaning: Periodic cleaning to remove dirt and interfering impurities to avoid affecting sensor operations.
• Anti-interference: Use a sensor with anti-interference in an environment with a lot of electromagnetic interference.
• Reset and calibration: After a long period of use, the sensor may need to be reset or calibrated according to the manufacturer’s instructions.
• Understand accuracy and resolution: Understand the sensor’s accuracy and resolution in terms of data collection capabilities.
• Safety: Ensure the sensor and related devices are installed safely to avoid danger to people and property.

7. Conclusion

Proximity sensors are widely used in many different fields. With the ability to detect the presence of objects without direct contact, proximity sensors help optimize processes, improve safety, and support the development of smarter products and services. In addition, if you are interested in modern automation solutions or want to stay up to date with the latest trends in the electronics manufacturing industry, join NEPCON Vietnam – the only exhibition event in Vietnam on SMT, Inspection Technology, etc  Equipment and Supporting Industries for Electronics Manufacturing are organized by RX Tradex Vietnam. Register right here.