Led diodes are used in many applications from commercial to home appliances. In this lecture i will discuss some applications of LEDs.
1. Seven Segment Display
A very common example of LEDs is seven segment display. A combination of 7 LEDs is used and we can display any decimal digit by forward biasing appropriate LEDs. The following figure shows a seven segment display chip. Which is able to display any decimal digit as well as a decimal point.
Fig-1: A Seven Segment Display
2. Remote Control
Remote control of many home appliances like TV or AC has infrared LED. The infrared LED sends an invisible light beam and on the other side photodetector is used to detect the light signal.
Each button on the remote has specific code. When any button is pressed LED converts this electrical code into light signals. The TV sensor recognizes the light signal and then microprocessor takes appropriate action based on the received coded signal.
Fig-2: A Remote Control
3. Fiber Optic
LEDs are are used in fiber optic cables. The light signal travels within fiber optic cable from one point to another point. Each light signal has some information. This fiber optic technology is the backbone of today’s internet.
Fig-3: Light in Fiber Optic
Picture taken from: https://en.wikipedia.org/wiki/Optical_fiber
4. Counting Products
Industrial application of LEDs is found in counting the products. For example a machine is automatically packing a product let’s say product is ball. Whenever a ball comes it cuts the LED light beam. The photodetector detects this interruption. The circuit behind photodetector senses the variation in current. When the required number of balls pass. The circuit stops further balls. Until the new empty box is ready to accept new balls.
Fig-4: Automatic Product Counter
5. Traffic Light
As LEDs are more power efficient and have long life time. So they are being used in traffic lights in place of previous incandescent bulbs. Arrays of LEDs are used with lenses to direct the light beams.
Fig-5: Traffic Light
6. LED Displays
Today LED displays are very common. They are used in sign boards, message boards and even in TV screens. In addition to this LED mobile displays are also available and many mobile phones carry this technology are already in the market.
Fig-6: LED Sign Board
7. Car Lights
High Intensity LEDs are widely used in cars. They are used in tail lights, backlights and in indicators as well.
Fig-7: LED tube panel in a car head light