What is the principle of infrared obstruction sensor? Classification and application

Infrared obstruction sensors are becoming one of the most advanced and useful technologies in many different fields. From industry, transportation to home security, infrared sensors not only help optimize production processes but also improve the quality of life and ensure safety for users. But what is an infrared obstacle sensor and what is the infrared obstacle sensor principle? This article will provide an overview of the principle of operation, common types of sensors, as well as their practical application and benefits. Let’s explore with RX Tradex to better understand this promising technology!

1. What is an infrared obstruction sensor?

An infrared obstacle sensor is an electronic device that uses infrared technology to detect and measure distances to surrounding objects. This sensor usually consists of two main parts: an LED that emits infrared light and an infrared receiver (usually an optical diode or optical transistor).

The wavelength of an infrared sensor is longer than visible light, so an infrared sensor emits rays invisible to the human eye, and any object with a temperature above 5 degrees Kelvin emits infrared radiation. 

There are 2 common types of obstacle detection infrared sensors today: active infrared sensor and passive infrared sensor.

• The active infrared sensor is composed of 2 main parts: the receiver and the light-emitting diode (also known as LED). Infrared light will reflect off objects as they approach the sensor, making it easier for the receiver to detect. In addition, infrared sensors are also considered proximity sensors because they are also applied to obstacle detection systems such as robots.
• Passive infrared sensors only receive infrared signals from heat sources such as humans, animals, or any other heat source without emitting infrared rays on their own. After receiving the signal, the sensor analyzes to determine the alarm conditions. Since it detects only without emitting infrared rays, this type of sensor is called passive.

2. Infrared obstacle sensor principle

The infrared obstacle sensing principle will be based on the detection of obstructions and reflection of infrared rays

• Obstruction detection ultrasonic sensors use light sensors to detect wavelengths of light in the infrared (IR) spectrum. This system uses LEDs that emit light of the same wavelength that the sensor is looking for. When the light from the LED encounters an obstruction, it reflects back and is picked up by the light sensor.
• As an obstruction approaches the sensor, the light reflected from the LED becomes stronger and enters the sensor with greater intensity. This sudden change in light intensity can be detected using a predetermined threshold. When the light intensity exceeds this threshold, the sensor triggers an alarm or takes action accordingly.

3. Circuit diagram design principle of infrared obstacle sensor

The infrared obstruction sensor works by emitting infrared light from the IR LED. When encountering an obstacle, infrared rays reflect back and are picked up by the infrared LED. This reflection reduces the internal resistance of the receiver LED, changing the input voltage of the Op-Amp.

The Op-Amp compares this voltage to a standard voltage from a rheostat R3. If the input voltage is greater than the standard voltage, the Op-Amp outputs a high-level signal (VCC). If smaller, the Op-Amp outputs a low-level signal (GND).

The resistors R1, R2 and R4 help protect and stabilize the operation of the LEDs, the R3 resistor regulates the sensitivity of the sensor.

4. Pros and cons of using an obstruction detection ultrasonic sensor

Ultrasonic obstruction detection sensors are a useful and effective tool for obstruction detection in a variety of applications. Despite the many benefits, they are not immune to some notable drawbacks. Here are some of the pros and cons of ultrasonic sensors that detect obstructions.

Advantage:

• Capable of measuring distances with high accuracy and good resolution, helping to detect obstacles clearly.
• Undemanding to ambient light conditions, works well both in darkness and bright light.
• The ability to detect a variety of materials such as metal, wood, plastic, and even liquids, something that many other types of sensors do not.
• Can operate over wide distances, from a few centimeters to several meters, suitable for a variety of applications.
• Safe and harmless to humans and pets, different from some other types of sensors that can emit radiation.

Shortcoming:

• The performance of ultrasonic sensors can be affected by environmental conditions such as temperature, humidity and air pressure.

• Materials that absorb sound or have uneven surfaces can reduce the detection efficiency of ultrasonic sensors.
• The resolution may be lower than some other types of optical sensors, especially in applications where high precision is required.
• Some ultrasonic sensors can be larger and heavier than others, limiting their use in compact devices.
• The price is more expensive than some other types of sensors such as infrared or optical sensors, which increases the cost of the system.

5. Application of infrared obstruction sensor

With the above advantages, the obstruction infrared sensor is widely applied not only in life but also in many other fields such as industry, transportation,… Some popular applications can be mentioned as:

• Automatic light on and off: The infrared sensor helps the light automatically turn on when someone enters the sensor area. When people move, the lights will automatically turn on according to each location they go, ensuring that spaces such as corridors and toilets are always illuminated at the right time. This not only creates convenience but also saves energy.
• Anti-theft system: Infrared sensor brings high efficiency in anti-theft, better home protection. When a burglar sneaks into a home or walks through a garden or balcony at night, sensors detect movement and trigger an alarm system immediately. The horn will howl, warning homeowners about illegal intrusion, helping them take timely measures.
• Automatic doors: Infrared sensors are also integrated into the automatic door system, helping the door open when someone approaches. This provides flexibility and convenience to users, while enhancing the experience of use in public and home spaces.
• Military and defense applications: In the military field, infrared sensors play an important role in guiding close-range air-to-air missiles on fighter aircraft. They help identify and track targets accurately, improve combat effectiveness and protect national security.

6. What to avoid when installing an infrared obstruction detection ultrasonic sensor

When installing an infrared obstruction detection ultrasonic sensor, there are some important things to avoid to ensure the performance and accuracy of the system such as:

• Avoid pointing sensors towards the air conditioning heater, because when operating, they will emit high temperatures and infrared radiation, causing interference to the sensor.
• Do not install sensors indoors outdoors as they are not designed to withstand rain and sun, which is prone to damage when installed outdoors, even without direct exposure to inclement weather.
• Avoid pointing the sensor toward window blinds as window blinds can create false alarms. When the window is open, the heat source from the outside penetrates along with the wind which can interfere with the sensor.
• In order not to suffer from electromagnetic interference, it is necessary to avoid installing infrared sensors near the power cord because infrared sensors are electronic devices operating at low voltage, so it should be limited to installation near high-voltage wires.
• Do not point the sensor towards a place with a lot of sunlight because they contain a lot of infrared radiation, which interferes and reduces the accuracy of the sensor.
• To avoid false alarms caused by pedestrians or joggers passing by, sensors should not be pointed directly towards the gate near the path.
• To ensure stable operation, avoid installing sensors on shaky surfaces.

In addition, to ensure the performance and reliability of infrared obstruction detection ultrasonic sensors, enterprises should pay attention to the following issues:

• Place the detector in the location through which the intruder must pass or in the place where the trap is created with crooks, to ensure early and effective detection.
• Observe the installation height specified in the manual, to ensure that the detector’s sensing area conforms to requirements.
• For specific requirements, recalculate the sensory area of the detector to meet the correct needs.
• Make sure there are no blind spots at the installation site, so that the detector can detect motion comprehensively.
• After installation is complete, double-check the detector’s sensing capabilities to ensure it works as expected.
• The detector is sensitive to infrared energy, so avoid installation near heat sources such as doors, air conditioners, stoves, to avoid unwanted disturbances.
• Selection of detectors that use pet discrimination technology to avoid false alarms caused by pet movements.

7. Summary

Above is information about the infrared obstacle sensor principle that RX Tradex has shared. With this knowledge, you can apply infrared obstacle sensors to your production process to optimize processes and improve operational efficiency. The implementation of this technology not only improves productivity but also ensures safety, product quality, and minimizes operating costs, bringing comprehensive benefits to businesses.

In order to bring more efficient manufacturing solutions in the electronics sector, RX Tradex will host NEPCON Vietnam 2024 in August. The event promises to bring a grand scale, bringing together hundreds of leading and prestigious brands from all over the world. This will be a great opportunity for your business to explore and update the most advanced technologies in the field of electronics manufacturing.