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This article is a comprehensive overview of both IR sensors and IR LEDs, including their functions, components, working principles, applications, and differences.
An Infrared light-emitting diode (IR LED) is a special-purpose LED that emits infrared rays ranging from 700 nm to 1 mm wavelength. Different IR LEDs may produce infrared light of differing wavelengths, just like other LEDs produce light of different colors.
IR sensor is a device that uses infrared technology to detect objects or changes in the environment. IR sensors can detect a wide range of physical properties such as temperature, motion, and proximity.
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IR LEDs are usually made of gallium arsenide or aluminum gallium arsenide. In complement with IR receivers, these are commonly used as sensors.
The appearance of an IR LED is the same as a common LED. Since the human eye cannot see infrared radiation, it is not possible for a person to identify if an IR LED is working. A camera on a cell phone camera solves this problem. The IR rays from the IR LED in the circuit are shown in the camera.
An IR LED is a type of diode or simple semiconductor. Electric current is allowed to flow in only one direction in diodes. As the current flows, electrons fall from one part of the diode into holes on another part.
In order to fall into these holes, the electrons must shed energy in the form of photons, which produce light.
It is necessary to modulate the emission from the IR diode to use it in the electronic application to prevent spurious triggering. Modulation makes the signal from IR LED stand out above the noise.
Infrared diodes have a package that is opaque to visible light but transparent to infrared. The massive use of IR LEDs in remote controls and safety alarm systems has drastically reduced the pricing of IR diodes in the market.
An IR sensor is an electronic device that detects IR radiation falling on it. Proximity sensors (used in touchscreen phones and edge-avoiding robots), contrast sensors (used in line following robots), and obstruction counters/sensors (used for counting goods and in burglar alarms) are some applications involving IR sensors.
An IR sensor consists of two parts, the emitter circuit, and the receiver circuit. This is collectively known as a photo-coupler or an optocoupler.
The emitter is an IR LED and the detector is an IR photodiode. The IR photodiode is sensitive to the IR light emitted by an IR LED. The photodiode’s resistance and output voltage change in proportion to the IR light received. This is the underlying working principle of the IR sensor.
The type of incidence can be direct incidence or indirect incidence. In direct incidence, the IR LED is placed in front of a photodiode with no obstacle.
In indirect incidence, both the diodes are placed side by side with an opaque object in front of the sensor. The light from the IR LED hits the opaque surface and reflects back to the photodiode.
IR Sensor Working PrincipleAn IR receiver LED and an IR transmitter LED are both types of light-emitting diodes (LEDs) that are used in infrared (IR) communication.
An IR receiver LED is a device that detects infrared signals from remote controls and other IR sources. It is typically a small, clear, or translucent device that is sensitive to IR light in a specific frequency range.
When an IR signal is detected, the IR receiver LED will emit a small amount of visible light, which can be used to confirm that a signal has been received.
An IR transmitter LED, on the other hand, is a device that emits infrared light in order to send signals to other devices. It is typically a small, clear, or translucent device that emits IR light in a specific frequency range. IR transmitter LEDs are commonly used in remote controls and other IR signaling devices.
In summary, the IR receiver LED detects the IR signal from the remote, and the IR transmitter LED emits the IR signal from the remote.
An IR sensor module is a device that contains an IR receiver LED and other components that are used to detect and process IR signals. It typically includes an IR receiver LED, a signal amplifier, and a demodulator circuit.
The IR receiver LED is used to detect IR signals, while the signal amplifier and demodulator circuit are used to amplify and process the received signal, respectively.
IR sensor modules are widely used in various electronic applications such as remote control, motion detection, proximity sensing, and more. They are commonly used in consumer electronics, robotics, and automation systems.
IR sensor modules come in various forms such as simple IR receiver modules and complex IR sensor modules with additional features such as signal processing and signal filtering. Some IR sensor modules also provide an output in a digital format that can be read by a microcontroller or microprocessor.
IR sensors find a wide variety of applications in various fields. Let’s take a look at a few of them.
There are several types of IR sensors, each with different characteristics and applications. Some common types include:
Here are some frequently asked questions about IR sensors and their answers:
A: IR sensors work by detecting infrared radiation emitted by objects in the environment. They typically use a photodiode or a phototransistor to detect the IR radiation and convert it into an electrical signal that can be processed and analyzed.
A: The range of an IR sensor depends on its type and the specific application. Some IR sensors can detect objects at a distance of several meters, while others are designed for short-range detection of a few centimeters. The sensor has a maximum range of around 40-50 cm indoors and around 15-20 cm outdoors
A: IR sensors have many advantages, including high accuracy, non-contact operation, and immunity to electromagnetic interference. They are also widely available and relatively inexpensive.
A: IR sensors are used in a wide range of applications, including security systems, motion detection, temperature measurement, proximity sensing, and many more.
A: Choosing the right IR sensor depends on your specific application and the parameters you need to measure. Consider factors such as the range, sensitivity, accuracy, and cost of the sensor, and consult with sensor manufacturers or experts in the field for guidance.
A: There are different ways to interface an IR sensor with a microcontroller, it depends on the type of IR sensor and the microcontroller you are using. Typically, the IR sensor output is connected to an input pin of the microcontroller, and the microcontroller reads the output and processes it accordingly.
A: It depends on the type of sensor and the specific application. Some IR sensors are designed for long-range detection and may be able to detect objects through walls or other obstacles, while others are designed for short-range detection and may not be able to detect objects through obstacles.
A: IR sensors may be affected by bright sunlight or other bright environments. To reduce the effects of ambient light, some sensors use filters or other techniques to block out unwanted light, while others use specialized sensors that are less sensitive to bright environments.
A: Some IR sensors, like reflective IR sensors, may not be able to detect transparent objects as they rely on the reflection of infrared light. However, other types of IR sensors, like transmissive IR sensors, are designed specifically for transparent object detection, by sensing infrared light that passes through an object.
A: Many IR sensors are designed to operate within a specific temperature range, and may not work properly outside of this range. Some IR sensors are specifically designed for use in extreme temperatures and can operate in a wide range of temperatures.
A: Some IR sensors may be affected by humidity, as humidity can change the properties of the infrared radiation they detect. To reduce the effects of humidity, some sensors use special materials or coatings that are less affected by humidity, while others use specialized sensors that are less sensitive to humidity.
A: IR sensors typically detect infrared radiation, which is outside the visible spectrum and is not associated with color. Some IR sensors are specifically designed to detect specific wavelengths of infrared radiation, but they don’t detect color.
Proximity sensors employ the reflective indirect incidence principle. The photodiode receives the radiation emitted by the IR LED once reflected back by the object. The closer the object, the higher will be the intensity of the incident radiation on the photodiode. This intensity is converted to voltage to determine the distance.
Proximity sensors find use in touchscreen phones, among other devices. The display is disabled during calls so that even if the cheek makes contact with the touchscreen, there is no effect.
In line following robots, IR sensors detect the color of the surface underneath it and send a signal to the microcontroller or the main circuit which then takes decisions according to the algorithm set by the creator of the bot.
Line followers employ reflective or non-reflective indirect incidence. The IR is reflected back to the module from the white surface around the black line. But IR radiation is absorbed completely by black color. There is no reflection of the IR radiation going back to the sensor module in black color.
The project is available at the line follower robot
Item counter is implemented on the basis of direct incidence of radiation on the photodiode. Whenever an item obstructs the invisible line of IR radiation, the value of a stored variable in a computer/microcontroller is incremented.
This is indicated by LEDs, seven-segment displays, and LCDs. Monitoring systems of large factories use these counters for counting products on conveyor belts.
The project is available at Infrared Object Counter
Direct incidence of radiation on the photodiode is applicable in the burglar alarm circuit. The IR LED is fit on one side of the door frame and the photodiode on the other. The IR radiation emitted by the IR LED falls on the photodiode directly under normal circumstances. As soon as a person obstructs the IR path and triggers an alarm.
This mechanism is used extensively in security systems and is replicated on a smaller scale for smaller objects, such as exhibits in an exhibition.
The project is available at Infrared Burglar Alarm
Using IR transmitter/receiver & music generator, audio musical notes can be generated and heard up to a distance of 10 meters. The IR music transmitter works off a 9V battery, while the IR music receiver works off regulated 9V to 12V.
The project is available at IR Music Transmitter and Receiver
There are various applications of IR sensors such as TV remote controllers, burglar alarms, and object counters. Here we have used infrared LEDs to make an object-detection circuit and also a proximity sensor for path-tracking robots.
The project is available at Playing With IR Sensors
This project demonstrates a wireless security system in which four pyroelectric infrared (PIR) motion sensors are placed on four sides – front, back, left, and right of the area to be covered. It detects motion from any side and turns on the audio-visual alarm. It also displays the side where the motion (intruder) is detected.
The project is available at Wireless Security System
Here we have used IR sensors to make an object detection circuit and a proximity sensor for path-tracking robots.
The Project is available at Object & Proximity Infrared Detector
Beginners most of the get confused in between these two names. Let’s solve this confusion-
IR Sensor and IR LED are two distinct components used in electronics, particularly in applications involving infrared technology. While they both deal with infrared radiation, they serve different purposes and have different functionalities. Here’s a breakdown of the key differences between IR sensors and IR LEDs:
In summary, the main difference between an IR sensor and an IR LED lies in their functions and roles within electronic systems. IR sensors detect and respond to IR radiation, allowing them to sense various parameters like temperature and motion.
On the other hand, IR LEDs emit IR radiation, which can be detected by IR sensors or used for communication and signaling purposes.
This article was first published on 30 October 2017 and recently updated on August 2023.
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