Display hardware Ecrã CRT

Ecrã CRT
Display hardware
• vector displays
– 1963 – modified oscilloscope
– 1974 – Evans and Sutherland Picture System
deflector vertical
ecrã
• 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?
canhão de electrões
deflector horizontal
• other
– stereo, head-mounted displays
– autostereoscopic displays
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Sinais de deflexão
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 definition is stored as a set of line-drawing
commands stored in a refresh display file.
– Refresh rate depends on number of lines
– Typicaly:
Hd
t
Vd
t
• Refresh cycle is 30 to 60 times each second
• 100 000 short lines at this refresh rate
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Vector Displays
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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Varrimento
Frame / Line Rate
Frame Rate:
TH = Tempo de varrimento Horizontal
FR 
TV = Tempo de varrimento Vertical
Hsinc
H
Hd
L
…
Vs inc
V
Vd
1
 FR  NL
TH
Lines / sec.
Linhas / seg.
Hz
Nº de linhas de um quadro:
N L 
TH
Frames / sec.
Quadros / seg.
Hz
Line Rate:
LR 
Hd
1
TV
t
TV
1

TH FR  TH
Nº de linhas visíveis:
Vd
NL
TV
NL '
t
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CRT a cores
Máscaras de cores
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Exemplo de monitor
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)
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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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Exemplo de monitor
Exemplo de monitor
5” CRT Monitor 01
Professional Large LCD Monitor
SPECIFICATION
Model
SMT-3222
SMT4022
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)
Grey levels: 16 at 100 cd/m2
Viewing Angle
(H/V) 178° / 178°
Panel Lamp Life
50,000HR
Video bandwidth: >12MHz -3dB
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
General
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
Gain control: Contrast control on front panel
Black level control: Brightness control on front panel
Warm up time: 15 seconds after power
Feature
Power requirements: 28V to MIL-STD-1275B
Power consumption total: <20 watts (at 450cd/m2)
June 2006
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Screen Aspect Ratio
4:3 / 16:9
Language
English / French / German / Italian / Portuguese / Russian / Spanish /
Swedish / Chinese / Japanese / Korean / Turkish / Taiwanese
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Placa Gráfica
Raster CRT
• Raster CRT pros:
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D0
RD
D3
– Allows solids, not just wire frames
– Low-cost technology (i.e., TVs)
– Bright! Display emits light
DAC
R
RAM
D4
A15
D7
A8
D8
D11
DAC
DAC
G
B
A7 -A0
• Cons:
– Requires screen-size memory array
– Discreet sampling (pixels)
– Practical limit on size
Counter
Counter
DotCLK
Osc
Hsinc
Vsinc
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Placa Gráfica
Color Map
Resolução dos DACs
Exemplo: 4 bits
=> Nº de cores = 2(3*4) = 4096 cores visíveis
Memória
M = NC * NL * PS
Exemplo: 256 colunas * 256 linhas * 12 bits/pixel = 768 kbits = 96 kBytes
DotCLK
DotCLK = FR * NL’ * NC
Exemplo: 60 quadros/seg * 256 linhas/quadro * 256 pixels/linha = 4 MHz
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Tabela de cores
Nº de cores simultâneas = 2 bits/pixel
Exemplo: 8 bits/pixel => 28 = 256 cores visíveis
Interlaçamento
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Page RAM
VRAM IBM 4MB
8192 x 1024 x 8
x 13
x 13
Address
A0 - A12
x 10
x 10
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3D-RAM
Graphic Computer
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RGB
Dual Buffer + Z
G
R
B
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HSL
Interactive Specification of Color
HSL - Hue, Saturation, Lightness
• Many application programs allow the user to specify colors of areas, lines,
text, and so on.
L
branco
H – Hue: Cor percebida por humanos
S – Saturation:
L – Lightness:
100%=cor pura
0%=tom de cinza
• Interactive selection:
vermelho
S
100%=branco
0%=preto
H
azul
verde
preto
• Perception of color is affected by surrounding colors and the sizes of colored areas
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YUV
CMY Models
Y – luma, brightness, luminancia
U, V – chrominance , crominância
• Used in electrostatic and ink-jet plotters that deposit
pigment on paper
• Cyan, magenta, and yellow are complements of red,
green, and blue, respectively
 C  1  R 
• White (0, 0, 0), black (1, 1, 1)
    
Y=R+G+B
U = Y-B
V = Y-R
 M   1  G 
 Y  1  B 
CMYK Model: K (black) is used
as a primary color to save ink
deposited on paper => dry quicker
- popularly used by printing press
Ideia:
Green
Yellow
(minus blue)
->
imagem monocromática
R = Y-V
B = Y-U
G = Y-R-B
Vantagens:
(minus red)
Cyan
Black
Blue
• Recetor monocromático pode usar apenas canal Y
• Resolução dos Canais U e V pode ser reduzida ….
Red
Magenta
(minus green)
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Variantes: Y’UV, YCbCr, YPbPr
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Y’UV
Analogue Television
Y’ – gamma corrected Y
• 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)
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http://www.answers.com/topic/interlace?cat=technology
http://en.wikipedia.org/wiki/PAL
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Video composto
Composite Video
Monitor
Video
Source
Hsync
L
Video
encoder
Composite
video
Video
decoder
Hsinc
H
Hd
L
Vsync
Vs inc
V
Vd
http://en.wikipedia.org/wiki/Composite_video
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Video composto
Televisão a cores
http://en.wikipedia.org/wiki/Pal
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CVBS
Composite Video
Color, Video, Blanking, Sync
Source
Video
encoder
Hsync
Vsync
R
G
B
Monitor
RGB
to
YUV
Y
U
V
Composite
video
Video Hsync
decoder
Vsync
Y
U
V
YUV
to
RGB
R
G
B
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PAL
PAL
http://en.wikipedia.org/wiki/DVB-T
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HSync On Green
Sync On Green
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SECAM - Sequential Couleur Avec Memoire
Resolução
• França, 1 de Outubro de 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
http://en.wikipedia.org/wiki/Display_resolution
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Flat Panel Displays
Liquid Crystal Displays (LCDs)
Volatile
• LCDs: organic molecules, naturally in crystalline
state, that liquefy when excited by heat or E field
• Crystalline state twists polarized light 90º.
• 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)
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
Thin Film Transistor
• Pixel is ON only during scan access.
TFT (Thin film transistor): a special kind of FET
• More Rows => shorter on-voltage time
• Reduced bright,
• poor contrast ratio,
• narrow viewing angle,
• fewer gray levels.
Basic FET
• Higher voltages => more crosstalk between neighbor pixels
• Scan frequency is limited by LC response delay.
• Flicker
MISFET
Solution
• placing an active element at each pixel
• switch and memory
• transistor and capacitor
TFT
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http://www.wikipedia.org
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TFT Active Matrix
TFT Active Matrix
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Display Technology: LCDs
CCFL Backlight
Cold-Cathode Fluorescent Lamp
• LCDs act as light valves, not light emitters, and
thus rely on an external light source.
• Driving Voltage: 100 ~ 400Vac, 30 ~ 50KHz
• Transmissive & reflective LCDs:
– (DC/AC Inverter required)
– Laptop screen: backlit, transmissive display
– Palm Pilot/Game Boy: reflective display
• 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
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CCFL Backlight
CCFL Backlight
Backlight Structure
Cold-Cathode Fluorescent Lamp
Direct
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
Side Lightguide
Low Heat Generation
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LED Backlight
LED Backlight
LED Backlight structure
• Driving Voltages: 2.1V ~ 8Vdc
• Brightness (Min): 70 cd/m2 5 ~ 30 cd/m2
• Luminous Color:
Direct
Yellow-Green, White, Green, Blue, Amber, Red
• Life Time: 100 000 Hrs
• Operating Temperature: -20° ~ +70° C
• Storage Temperature: -20° ~ +85° C
Side Lightguide
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LED Backlight
Plasma Panel
Advantages
Disadvantages
Very Long Life
Low Uniformity
Wide Temperature
Less brightness than CCFL
DC Single Operation
Price
•
•
•
•
•
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.
Various Colors
Lower thickness
Low Power Comsumption
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Plasma Panel
Plasma Panel
• Plasma Display Panel Pros
– Large viewing angle
– Good for large-format displays
– Fairly bright
• Cons
–
–
–
–
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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
FED
• Developed by Motorola and others during the 1990s
• Very similar to a CRT
• 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
FED
Advantages
Disadvantages
• More power efficient than LCD
• Less weight that same size LCD
• Erosion of the emitters
• Extremely high vacuum
required in order to operate
• Fewer total components
and processes involved
First models 2007
• 19.2-inches.
• 1 280 x 960 resolution
• brightness of 400cd/m2
• 20 000:1 contrast ratio
• Sony’sField Emission
Technologies, whose
purpose was to develop
the displays closed it
doors in 2009.
• Reason mainly due to
difficulty in raising funds
for manufacturing.
• Hard to manufacture for
commercial use
• Production difficulties
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Surface-conduction Electron-emitter Display
SED
• Co-developed by Canon and Toshiba Corporation
• Very similar to a CRT
• 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
Source: http://www.oled-display.info/what-means-sed-tv
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SED
SED
Advantages
• The overall power efficiency about ten times better than a LCD
of the same size.
• Less complex than LCD.
Prototype 2006
• 1080p 55-inch models
• Fast response time and high contrast ratio.
• Wide viewing angle advantages over the FED in manufacturing state.
• 450 nits of brightness
• 50,000:1 contrast ratio
• 1ms response time
Disadvantages
• Potential screen burn-in.
• Mass production difficulties.
Mass production delayed due to lawsuits between Canon and
Nano-Proprietary Inc concerning SED panel patent license
agreement.
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Organic Light-emitting Diode
OLED color
• Developed by Eastman-Kodak
• Only pure colors expressed when an electric current
stimulates the relevant pixels
• Two types: small molecule OLED and polymer OLED
• Primary color matrix arranged in red, green, and blue
pixels, mounted directly to a printed circuit board
• A Layer of organic material is sandwiched between
two conductors (an anode and a cathode) which are
between seal and subsrate
• Ambient light interference reduced with "micro-cavity”
structure -> improves overall color contrast
• Electro-luminescent bright light is produced from the
organic material when current is applied to the conductors
• 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
How OLED is built
OLED production
VS.
LCD production
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PLED
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)
Source: http://www.educypedia.be/electronics/pled.htm
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OLED
OLED
Advantages
• Samsung SDI exhibited a 40-inch OLED
panel at the FPD International 2008
• Can be printed onto any suitable substrate with inkjet (PLED)
• Flexible displays Great artificial contrast ratio and color potential
• No need for a backlight
• full HD resolution of 1920 x 1080
• contrast ratio of 1,000,000:1
• color gamut of 107% NTSC
• Great viewing angle
• Fast response times
• luminance of 200cd/m2 (peak luminance
of 600cd/m2)
Disadvantages
• At CES-2010 (Consumer Electronics Show):
• Lifespan (especially blue)
• Samsung showed several OLED 3D
Panels.
• Color balance issues (due to lifespan issues)
• Water damage
• Sony showed 24.5-inch prototype
OLED 3D television.
• Outdoor performance
• Power consumption
• Possible screen burn-in
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DMD
OLED
DMD: Digital Micromirror Devices
• Microelectromechanical (MEM) devices
• fabricated with VLSI techniques
Source: DisplaySearch Q2,09 Quarterly OLED Shipment and Forecast Report
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DLP - Digital Light Processing
• Implementação DMD da Texas Instruments.
• Tecnologia utilizada em projectores e ecrãs
rectro-projectados
• A imagem é criada por uma matriz de espelhos
móveis microscópicos montados num chip
semicondutor (DMD).
• Cada espelho dá origem a um píxel na imagem
projectada
Future
• Some of the technologies have faded after the
prototype phase
http://www.dlp.com
• 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
DMD – Digital Mirror Device
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Relação de Aspecto
Relação de Aspecto
• Display Aspect Ratio (DAR)
• Image Aspect Ratio (IAR)
Relação entre a dimensão horizontal e vertical de uma imagem ou de um
dispositivo.
DAR = W:H
• Storage Aspect Ratio (SAR)
SAR = NC:NL
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Relação de Aspecto de pixel
PAR <-> DAR
• Pixel Aspect Ratio (PAR)
PAR = (W:H) : (NC:NL)
= DAR : (NC:NL)
= DAR x (NL/NC)
• Relação entre a dimensão horizontal e vertical de um pixel.
W
W NC
pw
PAR 
ph
NL linhas
H
Y
NC colunas
Normalmente: PAR  1
H NL

W  NL
H  NC
DAR = PAR x (NC:NL)

W H
NC NL
Quando PAR = 1:1 => DAR = NC:NL
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4:3 -> 16:9
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