Input and Output Devices Topics

Foley & Van Dam, Chapter 4 Output Devices: • Display Devices - (CRTs, Monitors) • Hard Copy Devices - (Printers, )

Input Devices: • Alphanumeric input- (Keyboards) • 2D Inputs - (Joystick, Mouse, Digitizer etc) • 3D Inputs - (Glove, Space Ball) • Image Inputs - (Camera, Scanner)

CRT - Cathode Ray Tube Vector vs. Raster Display Vector Display: Cathode shadow mask x Only lines can be drawn (electron gun) and phosphor x Locations are converted to analog voltage coated screen applied to the deflection joke x Lines drawn by gradual change of voltage x Also known as random scan focusing x Refresh time is scene dependent anode deflection x Old fashioned - very uncommon today yoke

electron guns Raster Display: x Discrete grid of elements (frame buffer’s ) x Complex to draw “nice” lines shadow mask x Arbitrary shapes can be drawn x Frame buffer is scanned, one line at a time phosphors on x Used almost everywhere. glass screen

Terminology Hardcopy Devices

Pixel: Picture element. - Smallest accessible element in picture - Assume rectangular or circular shape Pen

Aspect Ratio: Ratio between physical dimensions of a (not necessarily 1)

Dynamic Range: The ratio between the minimal (not zero!) and the maximal light intensity a display pixel can emit

Resolution: The number of distinguishable rows and columns in the device. pin motion Measured in: - Absolute values (1K x 1K) or, Dot Matrix - Density values (300 dpi [=dots per inch]) ink covered ElectroMagnet tape Screen Space: A discrete Cartesian coordinate system of the screen pixels

Object Space: The Cartesian coordinate system of the universe, in which the objects (to be displayed) are embedded paper Hardcopy Devices Hardcopy Devices

high voltage ink drops deflection plates laser Ink Jet Printer drop generator gun paper Laser Printer charge laser electrode electric beam charger - + toner unused ink returned to drum reservoir paper

filter ink supply Color Laser Printer laser gun Thermal-Bubble Ink Jet Printer laser electric beam charger + - x4 color inks / toners drum Resistor is Bubble grows Bubble System heated and to maximum collapses. returns to paper bubble ink drop Drop initial state. nucleates. is ejected. breaks off.

Hardcopy Devices Hardcopy Devices

Thermal Wax Printer Dye Sublimation Printer

color wax roll color plastic roll

paper paper paper printer head thermal elements

plastic ink thermal elements

Input Devices Input Devices

Keyboard: Data Glove/Polhemus – For alphanumeric input –A modern attempt to provide the user with more degrees of Joystick: freedom – Usually two degrees of freedom –Common in Virtual Reality applications – Provides relative movement information –Polyhemus can provide six degrees of freedom (rotation and Mouse/Trackball translation) – A two degrees of freedom device controlled by a rolling ball Head Mounted Display –Although primary a , it can also track position – Provides relative movement information and orientation like Polhemus Digitizer/Tablet Space Ball – A two degrees of freedom device controlled by electro-magnetic or sound sensing –Six degrees of freedom sphere – Provides absolute position information Video Camera Touch Screen –Captures an array of image pixels – A CRT screen that can sense pressure on its surface Scanner Light Pen –Digitizes a hardcopy images – A two degrees of freedom sensing device – Synchronized with the CRT scan, it can locate a position on the screen Data Gloves Head Mounted Display

Space Ball Three Pass Color Scanner RGB

CCD array

CCD array

RGB Filters

Single Pass Color Scanner Single Pass Color Scanner

mirror CCD strips RGB Dichroic filters

B R G

Dichroic Filter O > cutoff

O < cutoff Low Cost Digital Camera Virtual Ink Mimio

CCD Array

Logitech Digital Pen