Display hardware Cathode Ray Tube vector displays Main - - PowerPoint PPT Presentation

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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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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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Magnetic Deflection

• Greater deflections
• Used in TVs

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Deflection Signals

t t Vd Hd

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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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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

V Vd Vsinc L H Hd Hsinc

Frame Rate: Line Rate:

Frames / sec. Quadros / seg. Hz Lines / sec. Linhas / seg. Hz

Nº de linhas de um quadro: Nº de linhas visíveis: V

T FR 1 

H H V

T FR T T L N     1 ' NL NL L N FR T LR

H

    1

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Color CRT

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Shadow Masks

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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

RD 1 Counter Counter Osc DotCLK R G B Hsinc Vsinc D0 D3 D4 D7 A

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A

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D8 D11 A -A

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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

Address A0 - A12 8192 x 1024 x 8 x 13 x 13 x 10 x 10

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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

V Vd Vsinc L H Hd Hsinc

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
• r 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
• f 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
• rganic 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
• f 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=2d 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