LEDs (light emitting diodes) emit light when operated in a forward biased direction. They are made of a PN junction of n-type and p-type semiconductors. When forward biased, electrons in the n-side are excited across the junction and combine with holes in the p-side, emitting photons. LEDs convert electrical energy directly to light and are used as indicator lights and in various applications like mobile phones, cameras, displays due to benefits like energy savings and durability. The document discusses the working, types, applications and benefits of LEDs.

1. VISHVAKARMA GOVERNMENT
ENGG. COLLEGE.
LED
(light emitting diode)

2. What is led?
• A light emitting diode (LED) is
essentially a PN junction opto-
semiconductor that emits a
monochromatic (single color) light
when operated in a forward biased
direction.
• LEDs convert electrical energy
into light energy. They are
frequently used as "pilot" lights in
electronic appliances to indicate
whether the circuit is closed or
not.

3. LED & its symbol

4. LED parts

5. Function of LED
• LEDs convert electrical energy into light
energy.

6. Working of LED(1)
• The light-emitting section of an LED is made
by joining n-type and p-type semiconductors
together to form a PN junction.
• When the PN junction is forward-biased,
electrons in the n side are excited across the PN
junction and into the p side, where they
combine with holes.
• As the electrons combine with the holes,
photons are emitted.

7. Working of LED(2)
• The PN -junction section of an LED is
encased in an epoxy shell that is doped with
light scattering particles to diffuse light and
make the LED appear brighter.
• Often a reflector placed beneath the
semiconductor is used to direct the light
upward.

8. Types of LED
Bargraph
7-
segment
Starburst
Dot
matrix

9. Applications of LED
• Medical Instrumentation
• Bar Code Readers
• Color & Money Sensors
• Encoders
• Optical Switches
• Fiber Optic Communication

11. Application of LED
• Mobile Phone
• PDA's
• Digital Cameras
• Lap Tops
• General Backlighting

13. Application of LED
• Full Color Video
• Monochrome Message Boards
• Traffic/VMS
• Transportation - Passenger Information
• Interior Lighting - Instrument Panels &
Switches, Courtesy Lighting
• Exterior Lighting - CHMSL, Rear
Stop/Turn/Tail
• Truck/Bus Lighting - Retrofits, New
Turn/Tail/Marker Lights

15. Applications of LED
• Traffic
• Rail
• Aviation
• Tower Lights
• Runway Lights
• Emergency/Police Vehicle Lighting

17. Benefits of LED
LEDs offer enormous benefits over
traditional incandescent lamps
including:
• Energy savings (up to 85% less power
than incandescent)
• Reduction in maintenance costs
• Increased visibility in daylight and
adverse weather conditions

19. Presentation by
Nisarg
Vishwesh
Vrajesh
Vijendra
Ajay
Bivin
Shijin
Abhimanyu

20. Hope you enjoyed our
presentation.
Thank you