8/2/2019 LED_Pres

http://slidepdf.com/reader/full/ledpres 1/37

8/2/2019 LED_Pres

http://slidepdf.com/reader/full/ledpres 2/37

Overview

• History

• Overview of How it Works

•

Circuit Diagram and Manufacturing• Consumer Applications

• Recap and Conclusion

8/2/2019 LED_Pres

http://slidepdf.com/reader/full/ledpres 3/37

Video Inputs

RCA

Component

HDMI

Coaxial

Digital Analog

8/2/2019 LED_Pres

http://slidepdf.com/reader/full/ledpres 4/37

Signal Conversion

• Digital to Analog (vice versa)• Logic Gates

• Handled by Circuits and then sent in common

instructions to display

8/2/2019 LED_Pres

http://slidepdf.com/reader/full/ledpres 5/37

Video Engine

• Advanced Color Management (ACM)

• Deinterlacing

•

Film Mode Detection Technology / Bad EditDetection

• TrueLife Enhancement

•

Motion Adaptive Noise Reduction• Cross Color Suppression

• Aspect Ratio Conversion

8/2/2019 LED_Pres

http://slidepdf.com/reader/full/ledpres 6/37

Polarity 101

• Like charges repel

• Opposite Charges Attract

8/2/2019 LED_Pres

http://slidepdf.com/reader/full/ledpres 7/37

CRT – Cathode Ray Tube

• The First Modern TV Technology

• Uses an Electron Beam to “paint” image on a

phosphor coated screen

• Pros: Response Time, Colors

• Cons: Size, Power Usage, Burn-In

8/2/2019 LED_Pres

http://slidepdf.com/reader/full/ledpres 8/37

Electron Beam Gun

• Beams of electrons are fired at the screen in

RGB color

• A steering with coil is used to change the

direction of the electrons

Steering Coil

8/2/2019 LED_Pres

http://slidepdf.com/reader/full/ledpres 9/37

Projection

• Big Screen Display Technology

• Projects a Video Image onto a mirror which

then magnifies it to be put on a screen

• Pros: Cheap, Large Screen

• Cons: Brightness, Response Time, Clarity, Size

8/2/2019 LED_Pres

http://slidepdf.com/reader/full/ledpres 10/37

LCD

• Started in Computer Monitors

• Independent pixels change their orientation

based on having an electric current

• Amount of voltage applied varies brightness

• Pros: Power Usage, Thin, Clarity

• Cons: Response Time

8/2/2019 LED_Pres

http://slidepdf.com/reader/full/ledpres 11/37

Plasma

• An electrode stimulates phosphor gas in an

individual pixel which then emits lights

• Pros: Colors, Response Time, Size

• Cons: Power Usage, Burn-In, Longevity

8/2/2019 LED_Pres

http://slidepdf.com/reader/full/ledpres 12/37

How Do We Get an Image?

• Board Takes Video Signal and Converts it to

Display Panel Outputs

• TFT Array and (PCB Chips drive Output to Panel)

8/2/2019 LED_Pres

http://slidepdf.com/reader/full/ledpres 13/37

TFT Array

• Pixel Addressing

• 1’s and 0’s

• Gate Line Switches on TFT

• Allows Current from Source Line

• Voltage Controlled by LDI controls Intensity of Colors

8/2/2019 LED_Pres

http://slidepdf.com/reader/full/ledpres 14/37

Grid of Transistors and Capacitors

• Thin-Film Transistors (Pixel Addressing)

• Liquid Crystal

•

CapacitorColumn (Voltage)

   R  o  w

   (   G  r  o  u  n   d   )

8/2/2019 LED_Pres

http://slidepdf.com/reader/full/ledpres 15/37

Why OLED?

• Power Consumption

• Size

•

New Applications• Scalability of Manufacturing

8/2/2019 LED_Pres

http://slidepdf.com/reader/full/ledpres 16/37

Physics of OLEDs

• How is light created?

 – Electrons gain energy to jump from conduction

level to valence level

 – Lose energy

• Photon emitted

• Colors created

• E=hv

8/2/2019 LED_Pres

http://slidepdf.com/reader/full/ledpres 17/37

Diodes Explained

• Simplest form of semiconductor

 – Doping

• Commonly platinum octaethylporphine (PtOEP)

• P-N Junction

8/2/2019 LED_Pres

http://slidepdf.com/reader/full/ledpres 18/37

Generic Band Diagram

8/2/2019 LED_Pres

http://slidepdf.com/reader/full/ledpres 19/37

Band Diagram for 2 Layer OLED

8/2/2019 LED_Pres

http://slidepdf.com/reader/full/ledpres 20/37

Display and Pixel Structure

8/2/2019 LED_Pres

http://slidepdf.com/reader/full/ledpres 21/37

OLED Schematic

•MOSFETs’ oxide layer

between the gate and the

channel prevents DC

current from flowing

through the gate

•Single MOSFET outputdrives many MOSFET

inputs

•Voltage-to-current

converter

8/2/2019 LED_Pres

http://slidepdf.com/reader/full/ledpres 22/37

OLED Schematic

Capacitor stores high

amounts of current so

when a small voltage hits

the circuit, the brightness

of the OLED changes.

8/2/2019 LED_Pres

http://slidepdf.com/reader/full/ledpres 23/37

I-V Characteristic of the OLED

OLED operates on a 6-16V range due to the high work function cathode and a

single emitting layer.

Silicon I-VCharacteristic

8/2/2019 LED_Pres

http://slidepdf.com/reader/full/ledpres 24/37

OLED Fabrication

1. Deposit and Pattern Anode

2. Pattern polymer layers (conducting &

emissive)

a) Spin Coating

b) Ink Jet printing

c) Screen printing

d) Web coating

3. Vacuum deposit and pattern cathode

8/2/2019 LED_Pres

http://slidepdf.com/reader/full/ledpres 25/37

OLED Fabrication

Materials are sputtered under a pulled vacuum to a small substrate located

far away from the sputtering source. An isotropic (uniform) layer of metal

falls onto the surface and binds.

8/2/2019 LED_Pres

http://slidepdf.com/reader/full/ledpres 26/37

Flexible OLED

• Different Substrates allow for new possibilities

• Sony has working prototypes

8/2/2019 LED_Pres

http://slidepdf.com/reader/full/ledpres 27/37

Thevenin

• OLEDs use lowest Thevenin voltage and resistance combination

Results in:

•

Long battery life (battery run displays)•Use as little voltage as possible to power screen•Save voltage for processes

• Best picture to power usage ratio• Univ. of Michigan recently developed 90 lumens per watt• Compare to 20-30 lumens per watt for LCD

8/2/2019 LED_Pres

http://slidepdf.com/reader/full/ledpres 28/37

Advantages & DisadvantagesAdvantages

• Robust Design

 – Variety of portable devices

• Viewing Angles (160-170 degrees)

• High Resolution

• Production Advantages

 – 20-50% cheaper than LCDs

• Hardware Content

 – Lighter, faster

 –Don't need lamps, polarizers,diffusers

• Power Usage

 – Less due to no lighting source

Disadvantages

• Lifetime of display

 – Blue Organic OLED films have

much shorter lifetimes (14,000

hours) than Red & Green films

(46,000-230,000 hours)• Current costs high, but future

looks promising

8/2/2019 LED_Pres

http://slidepdf.com/reader/full/ledpres 29/37

Types of OLEDs

Passive-matrix OLED

Intersections of the cathode and

anode=pixels where light is emitted

Active-matrix OLED

Require thin film transistor backplane

to switch individual pixels on or off 

8/2/2019 LED_Pres

http://slidepdf.com/reader/full/ledpres 30/37

Component Blocks

• Similar to a

computer

• Transfer and

controlinformation

output to

OLED Panel

8/2/2019 LED_Pres

http://slidepdf.com/reader/full/ledpres 31/37

Passive Matrix OLED

• Information – Registers

• Drivers

 – Voltage – Ground

• Resistance

•Low Active =Diode on

• Refresh Rate

8/2/2019 LED_Pres

http://slidepdf.com/reader/full/ledpres 32/37

8/2/2019 LED_Pres

http://slidepdf.com/reader/full/ledpres 33/37

Types of OLEDs

Transparent OLEDs

• Only have transparent

components (substrate,

cathode and anode)

• When turned on, it allows

light to pass in both

directions

• Can be used for heads-up

displays

Top-Emitting OLEDs

• Substrate that is either

opaque or reflective

• Can be used in smart cards

Foldable OLEDs

• Substrates made of very

flexible metallic foils or

plastics

• In cell phones and PDAs, can

reduce breakage

White OLEDs

• Emit white light that is

brighter, more uniform and

more energy efficient than

fluorescent lights

• Can be made in large sheets

8/2/2019 LED_Pres

http://slidepdf.com/reader/full/ledpres 34/37

Consumer Applications

• What OLED is doing for you?

 –Used in small screen devices

•Cell Phones

• PDAs

• Digital Cameras

8/2/2019 LED_Pres

http://slidepdf.com/reader/full/ledpres 35/37

Other Applications

• What else is OLED doing?

 –Sony 11” televisions ($2499)

 – Lamps

 –Used to support ground soldiers

• Near-eye microdisplays

8/2/2019 LED_Pres

http://slidepdf.com/reader/full/ledpres 36/37

The Future

• What will OLED do? – Wallcovering

 – Wearable electronic displays such as

"display sleeves" – Windshield displays and visor mounted

displays to be used by for pilots, drivers,

and divers

 – Camouflage systems

 – Flexible OLED

8/2/2019 LED_Pres

http://slidepdf.com/reader/full/ledpres 37/37

Recap

• Display Technology has been through many

changes

• OLED’s benefit from: Power Consumption,

Image Quality, Response Time, Manufacturing

• OLED’s have many applications beyond just

being displays, such as being light sources