Output: The Many Uses of Computers and Communications Audio, Video, Virtual Reality and Robots Outputs Types of Printers and Plotters Video Display Adaptors Types of Display Screens
Output devices translate information processed by the computer into a form that humans can understand. Several Types of Output Devices -Display Screens -Video-output devices -Printers and Plotters -Virtual-reality devices -Audio-output devices -Robots
Principal Kinds of Outputs Hardcopy – refers to printed outputs Softcopy – refers to data that is shown on a display screen or is in audio or voice form .It is not tangible.
Examples of Hardcopy - text or graphics printouts - film( microfilm, microfiche) Examples of Softcopy -Virtual reality -Robot
Display Screens: Softcopy Output
It is also called monitors
Output devices that show programming instructions and data as they are being input and information after it is processed.
Types of Display Screens
Cathode – Ray Tubes ( CRTs)
Flat Panels Display
Cathode – Ray Tubes ( CRTs)
The most common form of display screen.
It is a vacuum tube used as a display screen in a computer or video display terminal.
Flat Panel Displays
Much thinner, weigh less and consume less power than CRTs.
It is better for portable computers.
Made up of two plates of glass with a substance between them which is activated in different ways.
Liquid – Crystal Display
Consists of a substance called liquid crystal, the molecules of which line up in a way that alters their optical properties.
Flat panel screens are either active – matrix or passive matrix displays. Active –matrix Display – each pixels on the screen is controlled by its own transistor. It is much brighter than passive –matrix but they are more complicated and expensive. Passive- matrix Display - a transistor controls a whole row or column of pixels .It is less expensive and use less power than active – matrix.
Individual dots or picture elements that represented the images.
It is the smallest unit on the screen that can be turned on and off by the computer or made different shades.
Example of AMLCD
Example of PMLCD
Whether CRTs or flat-panel display, screen clarity depends on three qualities:
- Dot Pitch
- Refresh Rate
The clarity of sharpness of a display screen.
The more pixels there are per square inch, the better the resolution.
It is expressed in terms of the formula horizontal pixels x vertical pixels
-The amount of space between the centers of adjacent pixels.
The closer the dots, the crisper the image.
for crisp images, dot
pitch should be less
than .31 millimeter.
The number of times per second that the pixels are recharged so that their glows remains bright.
Produced more clarity
and richer colors.
Displays are refreshed
45 to 100 times per
Monochrome versus Color Screens
Monochrome Display screens
- It displays only two colors.
-Usually black and white, amber and
black, or green and black
It can display between 16 and 16.7 million colors ( depending on their type )
Text versus Graphics: Character Mapped versus Bitmapped Display
Character mapped display screens
display only text – (letters,
numbers and special characters).
They cannot display graphics
unless a video display adapter
card is installed.
- It permits the computer to manipulate pixels on the screen individually rather than as blocks.
It enables the software to
create a greater variety of
Video Display Adapters
A display screen must have a video display adapter to display graphics.
It is also called a graphics adapter card.
It is a circuit board that determines the resolution, number of colors, and how fast images appear on the display screens.
It is often built into the motherboard and also be an expansion card that plugs into an expansion slot.
Video Display Adapter Standards
VGA – Video Graphics Array
- Most common video
- It support 16 to 256
SVGA – Super Video Graphics Array
It will support 256 colors at higher resolution than VGA.
XGA – Extended Graphics Array
It supports up to 16.7 million colors at a resolution of 1024 x 768 pixels.
- video display adapters
and monitors must be
- computer software
and video display
adapter must be
Printers and Plotters: Hardcopy Output
Printer – is an output device that prints characters, symbols and perhaps graphics on paper.
- Impact Printers
- Nonimpact Printers
- Combined with a PC
It has a mechanisms resembling those of a typewriter.
It forms characters or images by striking a mechanism such as a print hammer or wheel against an inked ribbon leaving an image on paper.
Example: Dot-matrix printers
Dot- matrix Printer
Near letter Quality
Can print multipart forms
Low cost per page
Cannot produce high quality output of text and graphics
It is faster and quieter than impact printers because they have fewer moving parts.
It forms characters and images without making direct physical contact between printing mechanism and paper.
Laser Printer, Inkjet Printer, Thermal Printer
- Similar to a photocopying machine.
It uses the principle of dot-matrix printer in creating dot-like images.
However, these images are created on a drum, treated with a magnetically charged ink-like toner (powder) and then transferred from drum to paper.
Its typical speed is 8-200 pages per minute.
Its approximate cost is $400-$20,000.
Output of text and graphics
Very high speed
- High Cost, especially for color.
Can also form images with little dots.
It spray small electrically charged droplets of ink from four nozzles through holes in a matrix at high speed onto paper.
Even quieter than laser printer and produce an equally high quality image.
Its typical speed is 35-400+ characters per second.
Its approximate cost is $200-$2000.
Prints color text and graphics less expensive
Relatively slow; clogged jets; fewer dots per inch
-It can produce high quality color printing.
-It used colored waxes and heat to produce images by burning dots onto special paper.
-Its typical speed is 11-80character per second.
-Its approximately cost is $2000-$22000.
High quality color output of text and graphics
Can also produce transparencies
Black and White versus Color Printers
Impact printers are still needed however the choice between a laser printer and an inkjet comes down to how much you print and whether you need color.
It is a specialized output device designed to produce high quality graphics in a variety of colors.
Especially useful for creating maps and Architectural drawings, although they may also produce less complicated charts and graphs.
The three principal kinds of plotters are pen, electrostatic and thermal
The Paper Glut: Whither the Paperless Office
Supposedly, computers were going to make the use of paper obsolete, providing us with “paperless office” but in fact the opposite happened.
The Theater of output: Audio, Video, Virtual reality and Robots
Audio Output Devices
It includes voice output technology and sound output technology
It includes those devices that output voice or voice like sounds and those that output music and other sounds.
Voice Output Devices
Convert digital data into speech like sounds
These are such forms of voice outputs on telephones, machines, in cars in toys and in other devices.
Sound Output Devices
Produce digitized a sound, ranging from beep and chirps to music.
Video Output Devices
It includes videoconferencing and digitized television.
Videoconferencing and Video Editing
Videoconferencing is a method whereby people in different geographical locations can have a meeting and see and hear one another using computers and communications.
HDTV or ATV
High Definition television is a television system that features enhanced video and clear pictures. (Far superior to any seen on television today, appearing within a frame that is twice as wide.
Because the new system surpassed all expectations, The Federal Communication Commission gave it a new name. Advanced Television (ATV).
In place of analog channel, it can transmit not just one high definition image but five or six digital channels as good as current ones.
Virtual Reality and Simulation Devices
Virtual Reality (VR) is a kind of computer generated artificial reality that projects a person into a sensation of three dimensional spaces.
To achieve this effect, the following interactive sensory equipments are needed.
Glove – has sensors that collect data about your hand movements.
Software – gives the wearer of this special headgear and glove the interactive sensory experience that feels like an alternative to the realities of the physical world.
Simulators are devices that represent the behavior of physical and abstract systems.
Robot is an automatic device that performs functions ordinarily ascribed to human beings or that operates with what appears to be almost human intelligence.
Creative Output: The Manipulation of Truth in Art and Journalism
The ability to manipulate digitized output-images and sounds – has brought a wonderful new tool to art. However it has created some big new problems in the area of credibility.