Light emitting diode LED

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