1.1.3 Input and Output Devices Flashcards
Manual Input Devices
Input devices that require greater human intervention
Barcodes
Tend to be used for products
UPC-A
Universal Product Code version ‘A’ retail/warehousing
Code 128 transport/shipping
QR codes
Tend to be used for website links etc
Patterns of squares to link a website/information
Sensors
Allow for data to be obtained directly without user input. Take measurements of physical properties from real world surroundings
Analogue measurements
Data has no constant value - the data changes smoothly rather than in exact jumps
Examples of sensors
light, temperature, pressure, humidity
Monitoring vs control
Monitoring sees the sensor taking a measurement and reporting a value but not making a change. Control changes it
ADC
Analogue to digital convertor - puts signals in a format that a computer can understand (binary)
DAC
Digital to analogue convertor - means people can understand it
Output devices
Take data produced by a computer and turn it into human-readable form
Ink-jet printer
The circuit sends data to tell the printer what jets of ink to heat up and burst the bubbles to each part of the paper
Often used for photographs
Ink-jet advantages and disadvantages
+You can combine colours, high quality
+ cheaper than laser
-if you have a shared cartridge, one colour running out means the whole cartridge needs replacing
Laser printer
Instructions are sent where a drone rolls beside a roller with toner attracting paper onto the roller as paper comes past to roll the toner onto it
E.g. labels/brochures/fliers
Laser printer advantages and disadvantages
+ much quicker than ink-jet
- more expensive than ink-jet
Dot matrix printer
Strike an inked ribbon which imprints dots to form letters on the page
e.g printing in a dusty warehouse
Dot matrix printer advantages and disadvantages
+ useful where multi-part stationary is required
+ can work in damp/dirty atmosphere
- can’t be used for images/colour
- noisy
3D printers
Print using plastic filament, powdered resin, ceramic/metal powder or paper to make intricate objects including hollow areas
RFID
Radio frequency ID
Powered receiver emits radio frequency energy, transponder becomes energised and sends data
e.g. contactless payment, security, ID
Passive transponders
No power source, rely on radio waves from receiver for energy, transponders must be close
E.g. contactless payment
Active transponders
Use a large battery powered beacon, 300m broadcast range
E.g. tracking products in a supermarket
Actuators
Motors used in conjunction with sensors to control a machine
e.g. automatic doors
Loudspeakers/headphones
Data sent from computer to DAC, boosted by an amplifier and sent to a speaker
LCD monitors
Liquid crystal display screens
Contain groups of RGB diodes to form each pixel
Require backlighting with cold cathode fluorescent lights- CCFL
LED
Used instead of CCFL in LCD monitors
Cheaper, lighter, brighter, quicker, less likely to break
OLED screens
Organic LED
Use plastic rather than glass - flexible
Much brighter than LCD/LED
Generate their own light
Use much less power, less heat (lower fire risk)
Multimedia light projectors
Compact, high-resolution full colour projectors
Project text, images, video and audio contenting
