15-cp-54 15-cp-58 15-cp-70
TRANSCRIPT
LED, LCD and Touchscreens
Technology of the new Era
Group Members
Sheeraz Reg. # 15-CP-54 Hamza Irfan Reg. # 15-CP-58 Sikandar Rafique Reg. # 15-CP-70
LED’sLight Emitting Diodes
Content's
What are LED’s? History Working of LED Applications of LED Advantages of LED
What are LED’s?
LED’s are semi-conductors which emits monochromatic light when operated on forward biased direction.
LED’s convert electrical energy into light energy.
LED
History The first visible-spectrum (red) LED was developed in
1962 by Nick Holonyak Jr., while working at General Electric Company.
M. George Craford invented the first yellow LED and improved the brightness of red and red-orange LEDs by a factor of ten in 1972.
In 1976, T. P. Pearsall created the first high-brightness, high-efficiency LEDs for optical fiber telecommunications.
Working of LED LEDs create light by electroluminescence in
a semiconductor material. LED’s are basically P-N junction being operating in
forward biased direction. E.P.E is converted into E.M.E With each recombination of a negative and positive
charge a quantum of E.M.E is emitted in the form of a photon of light
Working of LED’s
Structure of LED
Applications of LED
Sensor applications Mobile applications Signal applications Illuminations
Sensor applications
Medical instrumentation Bar Code readers Color and Money sensors Optical switches Fiber Optic Communication
Bar code reader
Optical fiber
Color mark sensor
Mobile applications
Mobile phones PDA’s Tablet’s LED Flat screens Laptops
Mobile Phone
LED TV
Laptop
Signal applications
Traffic lights Rails Tower lights Runway lights Neon signs
Tower lightsTraffic Signs
Runway lights
Illuminations
Retail displays Flashlights Bulb replacements Emergency lights(exit signs)
Flashlight
LED Bulbs
Emergency signs
Advantages of LED
They're tiny and relatively inexpensive. They're easy to control electronically. They last virtually forever. That makes them brilliant
for traffic signals. The typical LED requires only 30-60 milliwatts to
operate. They are reliable that’s why they are soldered
directly I electric circuits.
Queries are openly accepted
Liquid Crystal Displays
Prepared & Presented by:Hamza Irfan {15-CP-58}
What is LCD?
• A Liquid Crystal Display is a slim, flat-panel mostly used to display text, pictures, videos, etc.
• This display is commonly used in laptops.
• Also available in desktop versions.
• Problems faced in CRT are solved by LCD.
What is LCD?
Fig. 1.0 LCD MonitorFig. 1.1 Calculator LCD
Brief History
• The history of LCDs starts with the discovery of liquid crystals in 1888 by Friedrich Reinitzer.
• Further works on liquid crystals were performed by Otto Lehmann in 1904.
Brief History• Later on, in 1963, Richard Williams along with George Heilmeier,
suggested using liquid crystals for making a display device.
• Dynamic Scattering method DSM was used to create first operational LCD by RCA (1968).
Brief History
• First LCD using Twisted Nematics (TN) was produced in 1971.
Fig. 4.0 Twisted Nematics
Development of LCDs
• In 1970s, first commercial LCD came into existence, and this technology was first used in quartz watch and in calculator displays.
• 1990s color LCDs were used in digital cameras and computer monitors.
Fig. 5.0 Digital Camera LCD
Development of LCDs
• 2000s Larger LCDs were used as home theatre. Full HD 1080p displays were produced.
Did you know?The largest LCD panel today is 110”.
Overview
• It is a type of light modulating display device. • Doesn’t directly emit light to create visualizations.
• Modifies the transmission of light to represent images.
• Rapidly gained popularity.
Did you know?Nearly 33% of all TVs sold in North America were LCDs
Working of LCD
Types of LCDs
• LCDs are characterized into two types:Passive Matrix LCDActive Matrix LCD
Fig.10.0 Passive Matrix vs. Active Matrix driving of LCD Monitors
Passive Matrix LCD
• Pixels are activated indirectly.
• Not so much expensive.
• Uses grids of Indium Tin Oxide (ITO).
• Pixels don’t refresh quickly.
• Animation might be blurry.
• Has a narrow viewing angle.
Active Matrix LCD
• Each pixel is activated directly.
• More expensive than passive ones.
• Uses thin film transistors.
• Animation is sharp, crisp and clean.
• Pixels have 4 transistors.
• Used in computer displays.
Advantages of LCDs
• Brightness - Produces very bright images due to high peak intensity.
• Emissions - Produces considerably lower fields than CRTs do.
• Distortions - No geometric distortion at default resolution.
• Power Consumption - Energy efficient and consumes 1/3 the power of a CRT.
• Size - Takes less desk space than CRTs do.
• Screen shape - Completely flat screen.
Disadvantages of LCDs
• Aspect ratio - The aspect ratio and resolution are fixed.
• Black level - Doesn’t show good result for black and dark gray colors.
• Contrast - Lower contrast than CRTs.
• Cost - Considerably more expensive in purchase than CRTs.
• Viewing angle - Viewing angle has restrictions. For clear vision, one must sit in front of the screen.
• Sensitivity - Can be more fragile than CRTs.
Queries are openly accepted!
Thankyou
Technology & Applications TOUCH SCREENS
Points to Discuss
Introduction History Components Working of Touch screen Types Comparison Applications
Introduction
A touch screen is a display that can detect the presence and location of a touch within the display area.
Interact
Fig:1.1Touch Screen
History
In 1965 ,the first touch screen was a capacitive touch screen developed by E.A. Johnson at the Royal Radar Establishment, Malvern, UK.
In 1971 ,a resistive touchscreen was developed by American inventor Samuel Hurst(founder of Elographics).
E.A Johnson Samuel Hurst
Components
A basic touch screen has three main components
Touch sensorControllerSoftware driver
Fig:2.2:Touch Screen
Fig:2.3:Controller
Fig:2.1:Driver
Working Of Touch Screen
Fig:3.1:Working Of Touch Screen
Types of Technology
Resistive Touch Screen Capacitive Touch Screen Surface Acoustic Wave Touchscreen Infrared Touch Screen Optical Touch Screen
Resistive Touch Screen
Fig:4.1:Resistive Touch Screen
1. Pet Film2. Top Circuit Layer3. ITO Conductive coating4. Space Dot5. ITO Conductive coating 6. Bottom circuit Layer7. Glass
Capacitive Touch Screen
Fig:5.1:Capacitive Touch Screen
1. Dust Cover Glass LENSE2. One optical adhesive3. ITO layer X-axis4. One optical adhesive5. ITO layer Y-axis6. Display
Surface Acoustic Wave Touchscreen
Fig:6.1:Surface Acoustic Wave Touchscreen
1. Transducers emit sound waves along sides2. Sound wave reflector3. Sensor4. Touch absorbs some energy from sound waves5. Controller
Optical/Infrared Touch Screen
Fig:7.1:Infrared Touch Screen
Optical-touch systems use an array of infrared (IR)light-emitting diodes (LEDs) on two adjacent edges of a display, with photo sensors placed on the two opposite edges to analyze the system and determine a touch event.
Optical Imaging
Fig:8.1:Optical Imaging
ComparisonTechnology Capacitive SAW Infrared Resistive
Transparence Very good >92%
Very good >92%
Very good >92%
75%~85%
Resolution Good Good Limited due tospacing of IRsensors
good
SurfaceContaminants/durability
Resistant tomoisture andother surfacecontaminants
Adversely affected bymoisture orSurfaceContaminants
Potential forFalse
activationor dead zonesFrom SurfaceContaminants
Unaffected by Surfacecontaminants.Polyester topsheet is easilyscratched
Display size 8.4"-21" 10.4"-30" 10.4"-60" up to 19"
Touch method Human touch finger, glovedhand or soft
tip
Can use any pointing
device
Can use any pointing
device
Table:1.1:Comparison between Capacitive ,SAW ,Infrared & Resistive
Applications
Tourism displays, Trade show display Stores, Restaurants, ATMs, Airline ticket terminals
and Transportation hubs. Digital jukeboxes, Computerized gaming, Student
Registration systems, Multimedia software , Scientific applications etc.
… Any Question
…THANK YOU