led ppt vgec ec engineering
TRANSCRIPT
VISHVAKARMA GOVERNMENT ENGG. COLLEGE.
LED(light emitting diode)
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.
LED & its symbol
LED parts
Function of LED• LEDs convert electrical energy into light
energy.
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.
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.
Types of LED
Bargraph 7-segment Starburst Dot matrix
Applications of LED
• Medical Instrumentation • Bar Code Readers • Color & Money Sensors • Encoders • Optical Switches • Fiber Optic Communication
Application of LED
• Mobile Phone • PDA's • Digital Cameras • Lap Tops • General Backlighting
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
Applications of LED• Traffic • Rail • Aviation • Tower Lights • Runway Lights • Emergency/Police Vehicle
Lighting
Benefits of LEDLEDs offer enormous benefits over
traditional incandescent lampsincluding:
• Energy savings (up to 85% less power than incandescent)
• Reduction in maintenance costs • Increased visibility in daylight
and adverse weather conditions
Presentation by
NisargVishweshVrajeshVijendra
AjayBivinShijin
Abhimanyu
Hope you enjoyed our presentation.
Thank you