Dispositivos de Sada Grfica

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Dispositivos de Saída Gráfica

• Bacharelado de Informática
• PUC-Rio
• Prof. Rodrigo Toledo

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CLASSIFICAÇÃO

• Processamento
• Vetorial
• Matricial
• Tipo
• Emissora de luz (ex monitores...)
• Não emissora de luz (ex impressoras...)

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Matricial x Vetorial
Imagem descrita comoum bitmap. (entrelaçado ou
não)
Imagem descrita como umaseqüência de comandos.
Obs Raster-calligraphic (combination of two)
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DEFINIÇÕES E NOMENCLATURAS

• Pixel (Picture Element)
• Dot Pitch
• Resolução (número de linhas e colunas)
• Resolução de cores
• Aspect ratio
• polegadas
• Persistência (olho humano e equipamentos)
• Refresh Rate e Frame Rate

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Refresh Rate e Frame Rate

• Refresh rate é a taxa de varredura (ou
  exposição). Em geral especificada em Hz.
• Frame rate é a quantidade de quadros diferentes
  projetados por segundo (ex cinema trabalha com
  24 frames por segundo)
• O olho humano trabalha em uma freqüência
  aproximada de 48Hz.

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Refresh Rate e Frame Rate

• Projetores antigos de cinema projetavam cada
  quadro 2 vezes, para se trabalhar na freqüência
  do olho humano.
• Projetores modernos de cinema projetam 3 vezes
  cada quadro.
• Os televisores na Europa trabalham a 50Hz,
  enquanto no Brasil e nos EUA trabalham a 60Hz.
• Por isso, dispositivos que fazem uso da
  estereoscopia ativa devem trabalhar em
  freqüências iguais ou superiores a 100Hz.
• Cuidado para não confundir com o frame rate para
  se ter a sensação de tempo real na resposta de um
  comando (geralmente o mínimo é 12 frames por seg.)

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PLOTTER

• VETORIAL
• TINTA

Bastante usado na engenharia
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IMPRESSORAS

• Matricial
• Jato de Tinta
• K
• CMYK
• Xerox
• pb
• colorida

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MONITORES

• LCD (displays de cristal líquido)
• Plasma (gás)
• CRT (tubo de raios catódicos)

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LCD Displays

• Liquid Crystal Display
• Organic molecules that remain in crystalline
  structure without external force, but re-aligns
  themselves like liquid under external force
• So LCDs realigns themselves to EM field and
  changes their own polarizations

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Passive LCD

• LCD slowly transit between states.
• In scanned displays, with a large number of
  pixels, the percentage of the time that LCDs are
  excited is very small.
• Crystals spend most of their time in intermediate
  states, being neither "On" or "Off".
• These displays are not very sharp and are prone
  to ghosting.

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Active Matrix LCD

• E field is retained by a capacitor so that the
  crystal remains in a constant state.
• Transistor switches are used to transfer charge
  into the capacitors during scanning.
• The capacitors can hold the charge for
  significantly longer than the refresh period
• Crisp display with no shadows.
• More expensive to produce.

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Plasma Display

• Basically fluorescent tubes
• High- voltage discharge excites gas mixture (He,
  Xe), upon relaxation UV light is emitted, UV
  light excites phosphors

• Large view angle
• Large format display
• Less efficient than CRT, more power
• Large pixels 1mm (0.2 mm for CRT)
• Phosphors depletion

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CRT(tubos de raios catódicos)

• Feixes de elétrons são emitidos contra camadas de
  fósforos, que sensibilizadas emitem radiação
  eletromagnética na faixa visível do espectro.
• Mesmo sistema dos televisores.

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CRT(tubos de raios catódicos)
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PROJETORES

• CRT
• LCD
• DLP (ou na verdade, DMD)

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Projections The basics
CRT
LCD and DMD
optical path
Screen
Screen
Lens
Lamp
Light source LampImage source LCD 2000 -
12000 lumens 1280 x 1024
Light source CRTImage source CRT 250 - 500
lumens 3200 x 2500

• high resolution
• geometry
• mature technology
• flexible positioning
• photo-realistic

• brighter
• maintenance
• alignment
• easy setup
• pixelization

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? CRT technology
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CRT technology
Lenses
CRTs
Screen
Electronics
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? CRT technology
Different tube size
7 inch 8 inch 9 inch 12 inch
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Scheimpflug correction
NOK
Projection cant be done on tilted surface -gt
focus problem!
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Scheimpflug correction
after correction
OK
Required for projection on tilted screens
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Raster lt-gtCalligraphic
Raster image 12801024 60Hz
Day mode 12801024 60Hz
16 ms
Pixel remains onscreen for 10 ns
Point remains onscreen for 1.5 µs
150 times longer !
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Calligraphy
Calligraphic Light points
Raster Image
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CRT technology
Strengths Resolution (up to 2500x2000) Good
contrast Easy geometrical correction /
flexibility Color matching and uniformity
Digital soft-edge Unbeatable video and data
image quality Life time picture tubes Proven
technology
Weaknesses Limited brightness up to 500 ANSI
Lumen Needs low ambient lighting conditions Setup
time Maintenance Not portable
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LCD - technology

• brighter
• maintenance
• alignment
• easy setup

Screen
Lamp
LCD
Lens
Light source LampImage source LCD
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LCD Panels
Panel sizes 1.1-1.8 inch (p-Si) 3 inch (a-Si) 6
inch (a-Si) 10 inch (single panel)
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LCD pros and cons

• Well-established technology, stable
• Compact, rugged, portable
• zero delay
• UXGA resolution available
• Efficient in passive stereo projection (see
  further)
• Response speed limited by LC material some
  smearing in fast moving images
• non-perfect black (contrast ratio 200-3001, but
  improving)
• pixellization

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Lens
XCube
LCD
R
B
G
Integrator
System
Dichroic Mirror
Lamp
Illumination unit
Projection Unit
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LCOS Liquid Crystal on Silicon

• Essentially LCD in front of a reflector
• Available for microdisplays, projection
• D-ILA is JVCs trade name for LCOS

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LCOS implementation

• LCD on top of CMOS chip that includes transistors
  and has reflective surface
• Aperture ratio is higher than that of LCD (so
  less pixel visibility)
• Efficiency comparable to LCD due to non-perfect
  reflection
• Easy to cool the chip!

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LCOS addressing

• Requires complex opticsside at which chip is
  illuminated is the same as where the light needs
  to be extracted from!

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LCOS integration
Complex structure required!
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LCOS pros and cons

• Higher resolutions possible (up to QXGA)
• small chip size (1.3 and smaller)
• good response speed
• good pixellization (smooth image)
• higher contrast possible up to and over 10001
  reported
• chips can be cooled to take high power
  illumination
• alignment hard due to small chip size high res
• difficult to integrate
• uniformity? (although seems to be countered now)

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DMD another reflective tech
Does not require polarized light!
Ant leg on DMD chip
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DMD microstructure

• Only allows on/off modulation!

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DMD grayscale synthesis

• Frame delay!
• 1 frame for de-interlacing
• 1 for sending data through CMOS chip
• 0-1 frame (depending on gray scale) for gray
  synthesis

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3-chip DMD integration
Each chip runs at 10 bits depth, 60 Hz NOTE 10
bit Linear Gamma equals 8 bit LCD Gamma
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3-chip DMD pros cons

• Excellent picture quality (pixels almost
  invisible)
• can take high power illumination
• long life (?)
• no smearing (but
• good intensity uniformity, good color matching
• good contrast (4001)
• Expenive!
• BIG!
• PWM artifacts
• TI monopoly
• Frame delay
• Resolution limited to SXGA
• Bright edge around chip makes optical blending
  difficult

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Single-chip DMD

• Sequential illumination of single DMD chip
• 3 or 4 segment color wheel
• chip runs at 8 bit, 240 Hz less bit depth!
• Compact
• Moving part inside, requires synchronization
• Motion artifacts (color breakup) due to color
  wheel

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OUTROS (DUET)
What is it?
IG
DUET
Active stereo _at_ 96 - 120 Hz
Dual passive stereo SIM 6, 48-60 Hz
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OUTROS (Soft Edge)

• Soft Edge
• ESEM Electonic Soft Edge Modulation
• OSEM Optical Soft Edge Modulation

RIGHT CHANNEL
CENTER CHANNEL
LEFT CHANNEL