What are IR Sensors and IR LEDs? How They Work and Uses

Author:admin Date: 2025-07-03 08:42 Views:99

Infrared technology uses infrared radiation, which is a form of electromagnetic radiation that is invisible to the human eye, to handle various applications. This infrared radiation is found on the electromagnetic spectrum beyond the visible light.

You can expect to come across infrared technology in thermal imaging, remote controls, heating, and communication systems. That is how you can come across applications such as IR sensors and IR LEDs.

What are IR Sensors?

What is IR Sensors

These are electronic devices used for detecting infrared radiation. They are mostly used for sensing objects, detecting motion, and measuring temperature by measuring the infrared light that the object emits or reflects.

Key Specifications of IR Sensors

An IR sensor is likely to have the following specifications to understand how it works.

Detection Range

This indicates how far an IR sensor can detect objects or measure temperature. This is usually stated in centimeters (cm) or meters (m).

Field of View (FOV)

This defines the area or angle that the sensor can detect or measure. It is mostly specified in degrees, but at times in angular units as well. A wider FOV means the sensor can easily cover a larger area, while a narrower FOV means the sensor offers a more focused detection.

Sensitivity

Sensitivity is when the IR sensors can detect small changes in the infrared radiation. So, a more sensitive sensor can detect even the smallest temperature variations or faint infrared signals.

Accuracy

This reflects how close the readings of the sensor match the actual values of an application. This is determined by the precision and reliability of the sensor. Having a higher accuracy means the measurements by the sensor are closer to the true values.

Response Time

The response time indicates how quickly a sensor can detect changes in infrared radiation. This is measured in milliseconds (ms). Having a faster response time means the sensor can react quickly to any changes in the environment.

Operating Voltage

This specifies the voltage range within which the sensor can function correctly. For example, you can come across IR sensors and IR LEDs operating within 1.5 to 5V, while others will have different voltage requirements.

Types of IR Sensors

Types of IR Sensors


There are two main types of IR sensors. They include the Active IR sensors and the Passive IR sensors.

Active IR sensors come with both an infrared emitter and a receiver. The emitter is usually an LED, while the receiver is a photodiode. So, these sensors work by sending out infrared light, and then the receiver will detect the light based on how the object reflects back.

Typical uses of Active IR sensors include proximity sensors for detecting obstacles, automatic doors, and any other application where there is a need to detect objects at a distance.

As for Passive IR sensors, they only have an infrared receiver and detect the infrared radiation emitted by other objects. So, their operation is quite simple. They will detect the changes in the infrared radiation that is within their field of view. This can include the movement of a heat source, such as an animal or a person.

The passive IR sensors are commonly used in automatic lighting, security systems, and motion-activated devices.

What are IR LEDs?

IR LED

These are LEDs designed to produce infrared radiation, which is invisible to the human eye, rather than visible light. The IR LEDs emit infrared radiation whenever current passes through them.

Due to their operation, IR LEDs have several applications. This includes remote controls, security systems, communication devices, night vision equipment, medical devices, and more. You can now combine IR sensors and IR LEDs in active IR sensors, depending on the use.  

Key Specifications of IR LEDs

Wavelength

IR LEDs operate at specific wavelengths. The common values for wavelength include 850nm and 940nm. The choice of wavelength largely depends on the sensitivity of the receiving sensor and application.

Forward Voltage

This is the voltage the LED needs to turn on and emit infrared radiation. This can vary from 1.2 to 1.5V depending on the specific LED.

Radiation Intensity

This is the amount of infrared light that the LED can emit. It is measured in milliwatts or milliwatts per steradian. Having a higher radiation intensity means you get a brighter light output.

Viewing Angle

This is also referred to as the beam angle, which indicates the angle at which the light is emitted. A narrower viewing angle means you have a more focused beam, while the wider angles provide broader coverage.

The typical viewing angles for IR LEDs can range from 20 to 160 degrees.

Operating Temperature

IR sensors and IR LEDs both have an operating temperature range where you can be assured of reliable performance. Operating the device beyond its stated operating temperature may lead to performance issues.

Types of IR LEDs

Types of IR LED


You will encounter two main types of IR LEDs: transmitter LEDs and receiver LEDs.

The transmitter LEDs or IR emitters are designed to emit an infrared light each time current passes through them. They are commonly used for applications such as remote controls, security systems, and other similar devices.

Examples of such LEDs include gallium arsenide (GaAs) and the aluminum gallium arsenide (AlGaAs).

The receiver LEDs or IR detectors are used to detect infrared light and then convert it into an electrical signal. They are usually used in conjunction with the transmitter LEDs to receive the signals or data transmitted through infrared light.

For example, this is a common design for a remote control system where the receiver LED in a device detects the infrared signal from a remote control and performs certain functions depending on the input.

How IR Sensors and IR LEDs Can Work Together

We have seen how IR sensors and IR LEDs are important in different applications above. What is important is to understand now how the two can be paired to work together. Below are some scenarios to keep in mind.

Object Detection

In the case of a reflective IR sensor setup, you have an IR LED that emits light, and the job of the IR sensor is to detect how close or far the object is based on the reflection.

Obstacle Avoidance

This setup will also have a combination of IR sensors and IR LEDs. This is where the infrared LED emits light, and when an object blocks the beam, the IR sensor detects this change and triggers a response.

Proximity Sensing

In this application, IR sensors are used to detect the presence of an object based on how infrared light is reflected. The IR LED generates the infrared light in this application.

Remote Controls

The IR LEDs can also be used in remote controls for transmitting signals to a device. On the other side, you have IR sensors that receive the signals from the IR LEDs and then convert them into electrical signals that perform specific functions depending on the input from the IR LEDs.

Difference Between IR LEDs And IR Sensors

Below is a table highlighting the key differences between the IR LEDs and IR Sensors.

Feature IR LED IR Sensor
Function Emitting infrared light Detecting infrared light
Role IR transmitter IR receiver
Primary use Sending signals, illumination Sensing or detecting IR signals
Types Transmitter and receiver IR LEDs Passive and active IR sensors
Examples TV remotes Motion detectors, proximity sensors

Advantages of IR Sensors and IR LEDs

  • Such devices require minimal power to operate. This makes them suitable for even portable devices.
  • Since the light is invisible to humans, it makes them suitable for applications where having light is undesirable. For example, when using remote controls to change channels on your TV, you do not need to see the light.
  • Durability is also a good factor for IR sensors and IR LEDs. This enables them to be integrated into a wide range of devices.
  • A wide range of applications is possible with these electronics. You can use them for detecting motion, proximity, and even temperature.
  • Both IR sensors and IR LEDs are cost-effective. You can utilize these inexpensive components to create a project that meets your specific needs.

Limitations

  • IR sensors may have limited range. They usually operate within a short range, and some even require a line of sight for an effective operation.
  • They can be sensitive to environmental factors such as temperature, humidity, and sunlight, which affect their performance.
  • IR LEDs are affected by dark objects that reflect less light. This can affect their accuracy in an application.

Conclusion

Both IR sensors and IR LEDs are built to deliver on different applications. You can come across many applications for both electronic devices, and sometimes they are combined into one device. If you are going to choose an IR sensor or IR LEDs, consider things such as the type, range, sensitivity, compatibility, wavelength, and more. Looking at the spec sheet can help you have a good understanding of what you are getting. They mostly do not need much maintenance to keep them working. Just keeping them clean should be enough most of the time.

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  • Frequently Asked Questions

    How do IR sensors and IR LEDs work together?

    It depends on the configuration. For example, in an IR system, the LED emits the infrared light while the IR sensor detects the light. For example, you can have a remote system where the remote emits the infrared light, and the TV has the IR sensor to intercept the signal.

    Can IR sensors be affected by light?

    Yes, the strong ambient light from the sun can often interfere with how the IR sensors work. This is especially the passive type. Having a proper shield or modulation technique can help reduce false triggers.

    Is there a difference between IR and visible LEDs?

    The main difference is the wavelength of each type. The IR LEDs emit infrared light, which is not visible to the human eye, compared to visible LEDs, which emit light in the visible spectrum.

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