1.5 Output Devices Flashcards
Output devices
Take data produced by a computer and turn it into a human-readable form
Inkjet operating costs
- The inkjet printers are sold at or below production cost
- Ink cartridges are dramatically marked up
Laser Printers
- Use dry powdered ink called toner
- Print quality is excellent
- Fast and reliable
Dot matrix printers
- Strike an inked ribbon which imprints dots to form letters on the page
- Useful where multi-part stationery is required
- Can work effectively in damp or dirty atmospheres
- Noisy, poor print quality and expensive to buy
3D printers
Print 3D objects
Applications of 3D printers
- Manufacturing of prosthetic limbs or orthotics
- Reconstructive surgery or general surgery
- Manufacturing parts for cars
Dangers of 3D printing
Blueprints of dangerous things could be distributed online
RFID (Radio Frequency ID)
- Use a transponder and receiver
- The powered receiver emits radio frequency and energy
- The transponder antenna in the bank card, mobile phone or tag becomes energized by radio waves
- The transponder can then send data to the receiver
Uses of RFID tags
- Security control points or identification of people, animals goods or valuables
- Shopping and supply chain traking for goods
- Banking and fast-payment systems
- As a potential replacement for barcode systems
Passive Tags
- Passive transponders used in bank cards for example, have no power source themselves and rely on the radio waves from the receiver for their energy
Active Tags
- Use a larger, battery powered beacon which can broadcast its own signal to receivers up to 300m away
Actuators
Motors that are commonly used in conjunction with sensors to control a mechanism (opening a valve or door, starting a pump, turning a wheel o fan, moving an aircraft aileron)
DAC
Digital to analogue converter to convert digital data into analogue signal which is boosted using an amplifier and then sent to a speaker
LCD (Liquid Crystal Display)
- Contain groups of red, green and blue diodes to form each pixel
- Require backlighting using Cold Cathode Fluorescent Lamps (CCFL) or LEDs as the crystals act as a light valve and do not emit light themselves
LEDs vs CCFLs
- LED reach their maximum brightness almost immediately
- Image is sharper with more realistic and vivid colours
- Produce a brighter and light, which leads to better picture definition
- Since LEDs are very small, this allows the screens to be much thinner in construction
- LEDs last almost indefinitely which makes the screens much more reliable
- LEDs consume very little power and therefore produce very little heat as well and reduce running costs