Transcript 幻灯片 1
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OUTPUT
Output Devices
Is any hardware component that conveys information to one or more people.
Two Types
Hard Copy ---- also called printout
Soft Copy
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Hard Copy
is an output device that produces text and graphics on a physical medium such paper or transparency film.
Are sophisticated printers used to produce high-quality drawings such as blueprint, maps, and circuit diagrams.
film on which materials are photographed at greatly reduced size; useful for storage; a magnification system is used to read the material
small sheet of microfilm on which many pages of material have been photographed; a magnification system is used to read the material.
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Soft Copy
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another computer
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Types of printers
Impact printers
Daisy wheel, band, chain and drum printers (old technology )
Dot Matrix printer
line printer
Non-impact printers
laser
ink jet
thermal
photo
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Printers
Types commonly used with microcomputers
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Laser printer
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Uses a technology similar to that used in a photocopying machine
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High quality
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Ink-jet printer
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Sprays small droplets of ink at high speed onto the surface of the paper
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inexpensive
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Thermal printer
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Uses heat elements to produce images on heat sensitive paper
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Very high-quality color artwork
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Laser printer
Ink-jet printer
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Thermal printer
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Photo Printer
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Printers
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Dot-matrix printers
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Using a series of small pins on a print head Inexpensive Noisy, quality not high
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screen
Also called VDU, terminal, monitor etc
Types of screens:
cathode ray tube ( CRT ): Most common screen
is a desktop monitor that is similar to a standard television because it contains a cathode-ray tube.
liquid crystal display (
)
Also called flat panel monitor, is a desktop monitor that uses a liquid crystal display instead of a cathode-ray tube to produce images on a screen.
sharp , flicker-free displays
Uses gas plasma technology which substitutes a layer of gas for the liquid crystal material in a flat panel monitor.
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Screen
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pixel :
Each spot is called a pixel , short for picture element, is the smallest element in an electronic image.
The colour of each pixel is stored in the graphics card as a number:
256 colours = 8bits(1 byte) per pixel
16 colours = 4 bits per pixel
Resolution
Describe the sharpness and clearness of an image, usually defined in pixels.
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Other output devices
Fax
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Send and receive images over telephone lines
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Data projectors
Is a device that takes the image from a computer screen and projects it onto a large screen so an audience of people can see the image clearly .
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microfilm
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Microfiche
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Plotter
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Plotter in 1984
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Voice Output
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Produce sounds for people Widely used devices
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Speakers & Headphones
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Connected with sound card
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Capture and play back recorded sounds
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Music player: MP3 Voice output is common and simpler than voice recognition
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Soft-drink machines, telephones, cars, language learning, supermarkets checkout counter, assist the physically challenged
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sound card
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The most commonly used monitors
Cathode-ray tubes(CRT)
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Similar to televisions Low cost and excellent resolution Size big, with radialization
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The most commonly used monitors
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Flat-panel monitors
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Also called liquid crystal display(LCD) monitors
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Much thinner than CRTs 2 types of flat-panel monitors
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Passive-matrix
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Scanning entire screen Need little power, not very clear
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Active-matrix(thin film transistor,TFT)
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Each pixel is independently activated Require more power, more expensive, better clarity
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Gas Plasma
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Monitor Standards
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Indicate screen quality Most common standards
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SVGA: Super Video Graphics Array
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800X600, for 15-inch monitors
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XGA: stands for Extended Graphics Array
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1024X768, for 17- and 19-inch monitors
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SXGA: stands for Super Extended Graphics Array
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1280X1024, 19- and 21-inch monitors
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UXGA: stands for Ultra Extended Graphics Array
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High-end engineering design and graphic arts
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