Karteikarten
Computer Science: Unit 4: Output Devices
Karten in diesem Stapel (38)
- 1Output DevicesTake data produced by a computer and turn it into a human readable form
- 2Give 4 common output devicesPrinters
Screens
Loudspeakers
Projectors - 3MonitorScreen attached to a computer. Also called a visual display unit (VDU). Display known as a soft coy of data
- 4What are 2 types of Monitors?LCD - Liquid Crystal Display
LED - Liquid emitting diode - 5What is a LCD?Liquid crystal material alters when electricity flows through it - changes make it more or less transparent. LCD screen has backlight that shines through liquid crystal layer. Sending different electrical signals to the display lets light through in different places, makes the display. Least expensive screen option. Microscopic color filter over each position changes color of each spot.
- 6What is a LED?light source. LED through a LCD layer = LED screen
- 7OLEDOLED - organic LED's - million of tiny OLEDS arranged in a grid to make a screen display.
- 8Advantages of OLED's/LED 6High quality but expensive, brighter picture.
Thinner and lighter, brighter, generate own lighting, larger view, less power consumed - 9Disadvantages of LED/OLED 2Wears out faster (screen)
Affected by water - 10ProjectorUsed to display computer images for large amount of people
- 11What are 2 common forms of Projectors?DLP Digital Light Projectors
LCD Liquid Crystal Display light projectors - 12DLPuses light that bounces off a grid of thousands of tiny mirrors that can move. Each mirror correspond to a single pixel - produce over a thousand shades of grey.
If want color - white light passes through color filters on a rapidly spinning wheel. - 13LCDBeam of light passes through the LCD onto a screen.
- 14Inkjet Printer Where suitable?Electrical signals control jets that spray ink onto the page
Suitable for home or small businesses - 15What are the 2 main types of Inkjet Printers?Thermal Bubble
Piezoelectric - 16Thermal BubbleBehind hundreds of print nozzles there are tiny resistors that create heat, causes ink to vaporize and form tiny bubbles. As bubble expands, ink is ejected onto the paper. As cools, the bubble collapses and draws in fresh ink - process continues till page printed.
- 17PiezoelectricWhen crystal receives a small electric current, it begins to vibrate. In words - ink ejected Outwards- new ink drawn in to replace.
- 18Benefits of Thermal Bubble 2Less expensive
Possible to use more print nozzles - 19Drawbacks of Thermal Bubble 3Produces larger droplet sizes
Only certain inks can be used due to high heat
More maintenance - high temperature - 20Benefits of Piezoelectric Crystal 4Very precise ink drop sizes
Wide range of ink types can be used
Can produce very small droplets
Can run for longer - less heat generated - 21What are some drawbacks of Piezoelectric Crystal? 2More expensive
Uses fewer print heads - 22What are some advantages 3 and disadvantages 5 of Inkjet Printers?Adv - Least expensive type of printer, produces high quality images
can print on media types
Dis - Not very fast, ink refills can be expensive and frequent, can be noisy, small paper tray - 23InterruptsSignals sent to the processor which cause it to stop what it's doing in order to service the interrupt
- 24How does a Inkjet Printer work?Data to be printed is sent to the printer driver. Driver puts data into a format that printer can process. Driver checks status of printer. Data sent to printer and is stored in a printer buffer. Sensors check if paper in paper tray. Sheet of paper fed into printer. When paper in correct position, print head moves over page, 4 ink colors used in correct amounts to give colors. Paper advanced to allow next line to be printed. Continues until printer buffer empty. Printer sends interrupt to processor requesting for more data sent
- 25Printer Drivers What is purpose?Software that converts data to be printed in a form specific to a given printer.
Purpose: allow applications to carry out the print job without needed to be aware of the specific format details of the printer being used. - 26Printer BufferTemporary memory which stores data until it is ready to be used/printed. This allows the processor to carry out other tasks while the relatively slow printing process can carry on in the background.
- 27Laser PrinterUses dust called toner. Contains a drum coated with static electricity - positive - which makes toner stick to the drum. A laser beam removes static electricity - makes negative - to leave a pattern of toner. Paper has negative charge. Charge removed once toner sticks so paper doesn't stick to drum. Paper goes through a fuser which melts the ink - makes permanent. Discharge lamp removes electric charge from drum so ready for next page.
Produced whole page at a time not line by line - 28Where is a Laser printer usually used?Schools
Businesses - 29What are the Benefits of Lasers?Larger toner cartage
cheaper printing cost per page
faster printing speed
text-high quality - 30What are the disadvantages of Lasers? 6Produces particulates and ozone gas - health issues
Maintenance can be costly
Physically larger
images lower quality
printer expensive - 31Dot Matrix PrintersImpact printers
Strike an inked ribbon which imprints dots to form letters on the page. - 32What are 2 benefits of Dot Matrix?Not affected much by dirty or damp atmospheres
Inexpensive to run - 33What are 4 disadvantages of Dot Matrix?Poor print quality
expensive to buy
Very noisy and slow
Color difficult - 343D PrinterMakes a physical object from a 3D digital model usually CAD
Design created on computer using CAD software
Object built up layer by layer - Additive Manufacturing
Or Subtractive Manufacturing - removing material - 352D CuttersUse high powered lasers to cut only cut in x and y axis
- 363D CuttersDesign created on computer - uses laser to cut material that use infra-red produces lots of heat - focused using a special lens - x, y and z axis
- 37What are the 2 main types of sound and output devices?Speakers
headphones - small speakers close to ear - 38What is DAC What is ADC?Digital analogue converter
Analogue digital converter
signal boosted by amplifier and sent speaker
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- Computer Science GCSE (Unit 4) Karteikarten am Computer Science: Unit 4: Output Devices, erstellt von HRYN red am 21/01/2021.
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