Light Emitting Diode is a light releasing diode that glows when an electric current flows through it. It is also known as LED. It is a two-lead light source based on semiconductors. It is widely used as a standard source of light in electrical equipment. LED converts electrical energy into light energy. Nowadays LEDs are most widely used in semiconductor diodes these diodes emit light when it forward biased, normally these diodes are formed by a P-N junction this is a semiconductor P-N junction this diode has two terminals anode and cathode. The anode is a positive terminal of a diode whereas the cathode is a negative terminal of a diode.
The P-N junction is surrounded by the transparent hard plastic epoxy resin hemispherical shaped shell to protect the diode from external shock this is a transparent cover of the diode. Though we have already said that LED is the same as ordinary P-N junction diode but it is also true that ordinary P-N junction diode does not emit light when it is forward biased.
I-V Characteristics of LED
There are different types of light-emitting diodes are present in the market and there are different LED characteristics which include the color light, or wavelength and radiation, light intensity. The important characteristic of the LED is color. In the starting use of LED, there is only red color. As the use of LED is increased with the help of the semiconductor process and doing the research on the new metals for LED, the different colors were formed which are shown in the graph below. LED emits light when it is forward biased. Hence it works in only forward biased conditions.
Advantages
- The cost of LED’s is less as they are small in size.
- By using the LED’s electricity is controlled. Hence electricity is consumed.
- With the help of the microcontroller, we can regulate the intensity of the LED
- It has a long Lifetime period. ( approximately 20 years )
- It is energy efficient.
- It has no warm-up period.
- It doesn’t get affected by cold temperatures.
- Its Color Rendering property is Excellent.
- It is an environmentally friendly diode.
- We can control it easily.
- It requires very low voltage and current is to drive the LED.
- It is shockproof.
Disadvantages
- Excess intensity of the light may affect on eyes.
- A small overload in voltage or current can damage the device.
- It has electrical polarity.
- Voltage sensitivity.
- Efficiency droop.
- Impact on insects.
Applications of Light Emitting Diode
- In the homes and industries LED is used as a bulb.
- The light-emitting diodes are used in vehicles.
- These are used in mobile phones to display the notification.
- At the traffic light signals led’s are used.
- It is also used in toys.