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Display hardware

• vector displays – 1963 – modified oscilloscope

– 1974 – Evans and Sutherland Picture System

• raster displays – 1975 – Evans and Sutherland frame buffer

– 1980s – cheap frame buffers bit-mapped PCs

– 1990s – liquid-crystal displays laptops

– 2000s – micro-mirror projectors digital cinema

– 2010s – high dynamic range displays?

• other – stereo, head-mounted displays

– autostereoscopic displays

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Cathode Ray Tube

• Main applications

– Oscilloscope

– TV

– Old monitors

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3

CRT

• Electron Gun creates an electron beam with controllable intensity.

• The deflection system moves the electron beam vertically and horizontally.

• When the electron beam strikes the phosphor, it produces visible light on the fluorescent screen.

• Only one point is lighted.

beam

Electron gun

Deflection

system

Light

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Electrostatic Deflection

• Small deflections

• Used in Osciloscopes

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5

Magnetic Deflection

• Greater deflections

• Used in TVs

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Deflection Signals

t

t

Vd

Hd

4

7

Vector Displays or random scan display

– The electron beam is directed only to the parts of the screen where a picture is to be drawn.

– Like plotters it draws a picture one line at a time

– Used in line drawing and wireframe displays

– Picture is stored as a set of line-drawing commands stored in a refresh display file.

– Refresh rate depends on number of lines

– Typicaly:

• Refresh cycle is 30 to 60 times each second

• 100 000 short lines at this refresh rate

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Vector Displays

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9

Vector Display

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Vector Displays

Advantages

Generates higher resolution than other (Raster) systems

Produces smooth line drawings

Disadvantage

Not usable for realistic shaded scenes

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Raster Scan

t

t

Vd

Hd

TH

TV

…

TH = Horizontal Scanning Period

TV = Vertical Scanning Period

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Frame / Line Rate

VVdVs inc

L

HHdHsinc

Frame Rate:

Line Rate:

Frames / sec.Quadros / seg.Hz

Lines / sec.Linhas / seg.Hz

Nº de linhas de um quadro:

Nº de linhas visíveis:

VTFR

1

HH

V

TFRT

TLN

1

'NLNL

LNFRT

LRH

1

7

13

Color CRT

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Shadow Masks

8

15 16

Monitor Example

40VM9H 9” B&W Monitor

Screen Size 8.74” Diagonal

Resolution >1000 TVL

Scanning Frequency Horizontal 15,750Hz / Vertical 60Hz (EIA)

Horizontal 15,625Hz / Vertical 50Hz (CCIR)

Video Input Composite 1Vp-p 75 Ohm loop through BNC via impedance switch

Video Output Composite 1Vp-p CVBS 75 ohms

Power Source 90V ~ 120VAC (60/50Hz)

Power Consumption <25W (EIA/CCIR)

Environmental

Operating Temperature 10°C ~ +40°C (14°F ~ 105°F)

Operating Humidity 30% ~ 80% (no condensation)

Mechanical

Dimensions (H x W x D) 222.25mm x 215.9mm x 254mm

(8.75” x 85” x 10”)

Weight 6.8 kg (15 lbs)

Safety Standards UL, LVD, CE, RoHS

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Monitor example 5” CRT Monitor 01

SPECIFICATION

Standard: CCIR 625 Line 50Hz and RS 170 60Hz interlaced.

Aspect ratio: Switchable between 4:3 and 4:1.77

Video impedance: 75 ohms ±2%.

Input type: Differential

Grey levels: 16 at 100 cd/m2

Video bandwidth: >12MHz -3dB

Gain control: Contrast control on front panel

Black level control: Brightness control on front panel

Warm up time: 15 seconds after power

Power requirements: 28V to MIL-STD-1275B

Power consumption total: <20 watts (at 450cd/m2)

June 2006

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Monitor Example

Model SMT-3222 SMT4022

General

Screen Size 32" 40"

Resolution (HxV) 1366 x 768 1920 x 1080

Pixel Pitch (mm) 0.511 x 0.511 (HxV) 0.46125 x 0.46125 (HxV)

Brightness(cd/m2) 450

Contrast Ratio 4,000:1 (Dynamic Contrast Ratio 40,000:1)

Response Time (ms) 8 (G-to-G)

Viewing Angle (H/V) 178° / 178°

Panel Lamp Life 50,000HR

Display Colors 16.7M

Horizontal Frequency 30 ~ 81KHz

Vertical Frequency 56 ~ 85Hz

Horizontal Resolution 600TV Lines

Comb Filter 3D

Sync Format NTSC : 3.5 / PAL : 4.43 / Secam

Feature

Screen Aspect Ratio 4:3 / 16:9

Language English / French / German / Italian / Portuguese / Russian / Spanish /

Swedish / Chinese / Japanese / Korean / Turkish / Taiwanese

Professional Large LCD Monitor

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Raster CRT

• Raster CRT pros:

– Allows solids, not just wire frames

– Low-cost technology (i.e., TVs)

– Bright! Display emits light

• Cons:

– Requires screen-size memory array

– Discrete sampling (pixels)

– Practical limit on size

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Graphics Card

DAC

DAC

DAC

RAM

RD1

Counter Counter OscDotCLK

R

G

B

Hsinc

Vsinc

D0

D3

D4

D7

A15

A8

D8

D11

A -A7 0

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Graphics Card

DACs’ resolution Exemple: 4 bits => Nr. of colors = 2(3*4) = 4096 visible colors

Memory M = NC * NL * PS

Exemple: 256 columns * 256 lines * 12 bits/pixel = 768 kbits = 96 kBytes

DotCLK DotCLK = FR * NL’ * NC = LR * NC

Exemple: 60 frames/second* 256 lines/frame * 256 pixels/line = 4 MHz

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Color Map

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Color Table

Nr of simulataneous colors = 2 bits/pixel

Exemple: 8 bits/pixel => 28 = 256 visible colores

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Page RAM

AddressA0 - A12

8192 x 1024 x 8

x 13

x 13

x 10

x 10

13

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VRAM IBM 4MB

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3D-RAM

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Graphic Computer

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Dual Buffer + Z

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RGB

B

R

G

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CMY Models

• Used in electrostatic and ink-jet plotters that deposit pigment on paper

• Cyan, magenta, and yellow are complements of red, green, and blue, respectively

• White (0, 0, 0), black (1, 1, 1)

B

G

R

Y

M

C

1

1

1

Magenta

Red

Yellow Green

Cyan

Blue

Black

(minus green)

(minus blue)

(minus red)

CMYK Model: K (black) is used

as a primary color to save ink

deposited on paper => dry quicker

- popularly used by printing press

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YUV

Y – luma, brightness, luminance U, V – chrominance

Variations: Y’UV, YCbCr, YPbPr

Ideia: Y = R + G + B -> monochromatic image

U = Y-B V = Y-R R = Y-V B = Y-U G = Y-R-B

Advantages: • A monochromatic receptor can use only the Y channel • Resolution for U and V channels can be reduced ….

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Y’UV

Y’ – gamma corrected Y

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HSL

H

S

L

branco

preto

azul

verde

vermelho

HSL - Hue, Saturation, Lightness H – Hue: Cor percebida por humanos

S – Saturation: 100%=cor pura 0%=level of gray

L – Lightness: 100%=white 0%=black

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• Many application programs allow the user to specify colors of areas, lines, text, and so on.

• Interactive selection:

• Perception of color is affected by surrounding colors and the sizes of colored areas

Interactive Specification of Color

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Analogue Television • How much bandwidth would we need for uncompressed digital television?

• European TV format has 625 scan lines, 25 interlaced frames per second, 4:3 aspect ratio

• It uses interlacing to reduce the vertical resolution to 312.5 lines

• Horizontal resolution is 312.5*(4/3) = 417 columns

• Bandwidth required 625*417*25 =

6.5MHz • Analogue colour information was quite cleverly added without increasing

bandwidth (NTSC, PAL and SECAM standards)

http://www.answers.com/topic/interlace?cat=technology

http://en.wikipedia.org/wiki/PAL

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Interlaced lines

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Composite Video

VVdVs inc

L

HHdHsinc

Monitor

Video

Source

Video

decoder

Video

encoder

L

Vsync

Hsync

Composite

video

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Composite Video

http://en.wikipedia.org/wiki/Composite_video

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Composite Video

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Color TV

http://en.wikipedia.org/wiki/Pal

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Composite Video

Monitor

Video

decoder

Video

encoder

R

Vsync

Hsync

Composite

video

G

B

RGB

to

YUV

Y

U

V

Y

U

V

YUV

to

RGB

R

G

B

Vsync

Hsync

Source

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CVBS

Color, Video, Blanking, Sync

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PAL

http://en.wikipedia.org/wiki/DVB-T

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PAL

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SECAM - Sequential Couleur Avec Memoire

• France, 1 October 1967

• developed in France (predominantly a political decision).

• used in France and territories, C.I.S., much of Eastern Europe, the Middle East and northern Africa.

• Line Frequency - 15.625 kHz

• Scanning Lines – 625 (same as PAL)

• Field Frequency - 50 Hz

• Color Signal Modulation System FM Conversion System

• Color Signal Frequency - 4.40625 MHz/4.250 MHz

• Burst Signal Phase settled

• Video bandwidth - B,G,H: 5.0 MHz; D,K,K1,L: 6.0 MHz

• Sound Carrier - B,G,H: 5.5 MHz; D,K,K1,L: 6.5 MHz

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HSync On Green

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Sync On Green

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Resolutions

http://en.wikipedia.org/wiki/Display_resolution

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Flat Panel Displays Volatile

• Pixels are periodically refreshed to retain their state

• Refresh many times a second

• Otherwise image will fade from the screen

• Plasma, LCD, OLED, LED, ELD, SED and FED-displays

Static

• Material with bistable color states

• No energy needed to maintain image, only to change it.

• Slow refresh state

• Deployment in limited applications

• Cholesteric displays, outdoor advertising, e-book products

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Liquid Crystal Displays (LCDs)

• LCDs: organic molecules, naturally in crystalline state, that liquefy when excited by heat or E field

• Crystalline state twists polarized light 90º.

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Liquid Crystal Displays (LCDs)

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Color Filters (RGB)

Conventional color displays use a specific sub-pixel arrangement.

• at high pixel densities, RGB or RGB Delta arrangement is adequate.

• when the number of pixels is limited, the GRGB arrangement can be used.

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Passive Matrix LCD Problems • Pixel is ON only during scan access.

• More Rows => shorter on-voltage time

• Reduced bright,

• poor contrast ratio,

• narrow viewing angle,

• fewer gray levels.

• Higher voltages => more crosstalk between neighbor pixels

• Scan frequency is limited by LC response delay.

• Flicker

Solution • placing an active element at each pixel

• switch and memory

• transistor and capacitor

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Thin Film Transistor

Basic FET

MISFET

TFT

TFT (Thin film transistor): a special kind of FET

http://www.wikipedia.org

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TFT Active Matrix

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TFT Active Matrix

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Display Technology: LCDs

• LCDs act as light valves, not light emitters, and thus rely on an external light source.

• Transmissive & reflective LCDs:

– Laptop screen: backlit, transmissive display

– Palm Pilot/Game Boy: reflective display

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CCFL Backlight

• Driving Voltage: 100 ~ 400Vac, 30 ~ 50KHz

– (DC/AC Inverter required)

• Brightness (Min):

– 1 000 cd/m2 (direct application)

– 450 cd/m2 (side application)

• Luminous Color: White

• Life Time: 15 000 ~ 20 000 Hrs

• Operating Temperature: 0 ° ~ +60° c

• Storage Temperature: -20 ° ~ +70° c

Cold-Cathode Fluorescent Lamp

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CCFL Backlight

Backlight Structure

Direct

Side Lightguide

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CCFL Backlight

Advantages Disadvantages

Simple Design Narrow Drive Temperature

Good for Color LCD

High Frequency & AC Signal

Operation

Good Uniformity Needs DC/AC inverter

High Brightness

Long Life

Low Heat Generation

Cold-Cathode Fluorescent Lamp

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LED Backlight

• Driving Voltages: 2.1V ~ 8Vdc

• Brightness (Min): 70 cd/m2 5 ~ 30 cd/m2

• Luminous Color:

Yellow-Green, White, Green, Blue, Amber, Red

• Life Time: 100 000 Hrs

• Operating Temperature: -20° ~ +70° C

• Storage Temperature: -20° ~ +85° C

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LED Backlight

LED Backlight structure

Side Lightguide

Direct

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LED Backlight

Advantages Disadvantages

Very Long Life Low Uniformity

Wide Temperature Less brightness than CCFL

DC Single Operation Price

Various Colors

Lower thickness

Low Power Comsumption

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Plasma Panel

• Similar in principle to fluorescent light tubes.

• Each element is a small gas-filled capsule.

• When excited by electric field, emits UV light.

• UV excites phosphor.

• Phosphor relaxes, emits some other color.

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Plasma Panel

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Plasma Panel

• Plasma Display Panel Pros

– Large viewing angle

– Good for large-format displays

– Fairly bright

• Cons

– Expensive

– Large pixels (~1 mm versus ~0.2 mm)

– Phosphors gradually deplete

– Less bright than CRTs, using more power

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Field Emission Display

• Developed by Motorola and others during the 1990s

• Very similar to a CRT matrix

• Utilizes an electron emitter which activates phosphors on a screen

• In CRT an electron gun scatters the charged particles

• Each FED pixel has its own corresponding electron source

• At first conical electron emitters (known as a "Spindt tip")

– nowdays carbon nanotubes

• Electrons in a FED are not produced by heat

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FED

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FED

Advantages

• More power efficient than LCD

• Less weight that same size LCD

• Fewer total components

and processes involved

Disadvantages

• Erosion of the emitters

• Extremely high vacuum

required in order to operate

• Hard to manufacture for

commercial use

• Production difficulties

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FED

First models 2007

•19.2-inches.

•1 280 x 960 resolution

•brightness of 400cd/m2

•20 000:1 contrast ratio

•Sony’s Field Emission

Technologies, whose

purpose was to develop

the displays closed it

doors in 2009.

•Reason mainly due to

difficulty in raising funds

for manufacturing.

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Surface-conduction Electron-emitter Display

• Co-developed by Canon and Toshiba Corporation

• Very similar to a CRT matrix

• Utilizes an electron emitter which activates

phosphors on a screen

• The electron emission element is made from few

nanometers thick electron emission film

• No electron beam deflector required

• Separate emitter for each color phosphor, 3/pixel

or 1/sub-pixel

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SED

Source: http://www.oled-display.info/what-means-sed-tv

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SED

Advantages

•The overall power efficiency about ten times better than a LCD

of the same size.

•Less complex than LCD.

•Fast response time and high contrast ratio.

•Wide viewing angle advantages over the FED in manufacturing state.

Disadvantages

•Potential screen burn-in.

•Mass production difficulties.

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SED

Prototype 2006

• 1080p 55-inch models

• 450 nits of brightness

• 50 000:1 contrast ratio

• 1ms response time

Mass production delayed due to lawsuits between Canon and

Nano-Proprietary Inc concerning SED panel patent license

agreement.

In 2010 Canon announced project shut down.

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Organic Light-emitting Diode

• Developed by Eastman-Kodak

• Two types: small molecule OLED and polymer OLED

• A Layer of organic material is sandwiched between

two conductors (an anode and a cathode) which are

between seal and subsrate

• Electro-luminescent bright light is produced from the

organic material when current is applied to the conductors

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OLED color

• Only pure colors expressed when an electric current

stimulates the relevant pixels

• Primary color matrix arranged in red, green, and blue

pixels, mounted directly to a printed circuit board

• Ambient light interference reduced with "micro-cavity”

structure -> improves overall color contrast

• Organic layer adjusted for each color for strongest light

• Colors purified with color filter without the need for

polarizer -> outstanding color purity.

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OLED

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How OLED is built

OLED production

VS.

LCD production

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PLED

Source: http://www.educypedia.be/electronics/pled.htm

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Different OLED technologies

• AM OLED = Active Matrix OLED device

• FOLED = Flexible Organic Light Emitting Diode (UDC)

• OLED = Organic Light Emitting Diode/Device/Display

• PhOLED = Phosphorescent Oragnic Light Emitting Diode (UDC)

• PLED = Polymer Light Emitting Diode (CDT)

• PM OLED = Passive Matrix OLED device

• POLED = Polymer Oragnic Light Emitting Diode (CDT)

• RCOLED = Resonant Coloe Oragnic Light Emitting Diode

• SmOLED = Small Molecule Ogranic Light Emitting Diode (Kodak)

• SOLED = Stacked Oragnic Light Emitting Diode (UDC)

• TOLED = Transparent Oragnic Light Emitting Diode (UDC)

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OLED

Advantages • Can be printed onto any suitable substrate with inkjet (PLED)

• Flexible displays Great artificial contrast ratio and color potential

• No need for a backlight

• Great viewing angle

• Fast response times

Disadvantages

• Lifespan (especially blue)

• Color balance issues (due to lifespan issues)

• Water damage

• Outdoor performance

• Power consumption

• Possible screen burn-in

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OLED

• Samsung SDI exhibited a 40-inch OLED

panel at the FPD International 2008

• full HD resolution of 1920 x 1080

• contrast ratio of 1,000,000:1

• color gamut of 107% NTSC

• luminance of 200cd/m2 (peak luminance

of 600cd/m2)

• At CES-2010 (Consumer Electronics Show):

• Samsung showed several OLED 3D

Panels.

• Sony showed 24.5-inch prototype

OLED 3D television.

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OLED

Source: DisplaySearch Q2,09 Quarterly OLED Shipment and Forecast Report

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3LCD Projectors

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DMD DMD: Digital Micromirror Devices

• Microelectromechanical (MEM) devices

• fabricated with VLSI techniques

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DLP - Digital Light Processing • DMD implementation by Texas Instruments.

• Used in projectors and also back-projected displays.

• The image is created by a matrix of microscopic moving mirrors mounted in an integrated circuit (DMD).

• Each mirror creates one pixel in the projected image.

http://www.dlp.com

DMD – Digital Mirror Device

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Future

• Some of the technologies have faded after the

prototype phase

• OLEDs are the most promising

• Flexible displays

• Printing technology

• Printed vs non printed

• Rigid vs flexible

• Inorganic vs organic,

• Cost of materials vs process

• New technologies still in development

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Projection

x

W

d

W=2 d tan(x/2)

H=2d tan(y/2)

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Throw ratio

Throw = distance from projector to screen (d)

Throw ratio (TR):

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Projector Example