Input and Output Devices Flashcards by Cristian Kim

Describe how a barcode scanner works (5)

red laser shone on barcode

light reflected back (white lines reflect more light)

sensors detect light

microprocessor decodes data

bars will give different binary values

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Barcode applications (3)

supermarket checkout

library system

Airport check-ins

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Disadvantages of keyboard (3)

dirt/food can get into keys

easy to make a mistake

can be slow

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Advantages of concept keyboard (2)

fewer typing errors

stops dirt/food as it has protective layer

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Touchscreen application (3/5)

Ticket/ information kiosk

Mobile phone/ tablet

Control room interface

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How inkjet printer works (3)

print head moves nozzles side to side across page

nozzles spray liquid ink droplets on paper

ink droplets created using piezoelectric or thermal bubble technology

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Benefits of laser printer (3)

can print duplex

Faster printing

Cheaper long term (does not have to purchase ink cartridges)

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Advantages of inkjet printer (3)

Cheap to initially purchase

high quality output

relatively quiet

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Inkjet disadvantages (3)

ink cartridges dont last long

expensive to run

printing can smudge

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How laser printer works (4)

Uses toner cartridges

Uses charged print drum

Uses static electric charges

Toner fused to paper

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Application of 3D printers(3)

prototypes/models

parts of vintage car

creating museum artifacts

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When are inkjet printers used? (3)

high quality images

photographs

low volume printing

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When are laser printers used? (2)

high speed printing

large volume printing

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What are barcodes made up of?

series of black and white parallel lines

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Appearance of QR code

matrix of black squares on white background

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How do resistive touchscreens work (5)

uses multiple layers of material

transmits electric currents

when touched, top layer pushed into bottom layer

electric current changes

location of touch found

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Advantages of resistive (2)

cheap technology

can use gloved fingers to input

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Disadvantages of resistive (3)

does not allow multi-touch

poor visibility in sunlight

vulnerable to scratches

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How do capacitive touchscreens work (4)

electric fields created between glass layers

sensors monitor electric field

touched = electrostatic charge transferred to finger

location of touch calculated

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Advantages of capacitive touchscreen (3)

allows multi-touch

durable surface

good visibility in sunlight

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Disadvantages of capacitive touchscreen (2)

cannot use when wearing gloves

screen will shatter on impact

How do infrared touchscreens work? (5)

infrared rays sent across screen from edges

rays form grid around screen

sensors capture beams

infrared ray broken by finger touching screen

calculation made where beam broken to locate touch

Advantage of infrared touchscreens (3)

allow multi-touch

allows gloved fingers to be used

durable

Laser printer disadvantages (3)

larger carbon footprint

more time to warm up

toner cartridge more expensive

Disadvantages of infrared touchscreens (3)

sensitive to moisture sensitive to light interference accidental activation if infrared disturbed

How QR code works (7)

scanned by camera light reflected back black squares reflect less than white squares 3 large squares define alignment square's data decoded - each square has binary value processed by app links to website or document

QR code benefits (3)

hold more data easier to read - can be read just using cameras easier to transmit QR codes

QR code disadvantages (2)

can be used to transmit malicious codes more than one QR format available

Why might a capacitive touchscreen not work if the person is wearing gloves (2)

gloves are not conductive gloves block charge from finger

How can a mobile phone be used without removing gloves

use capacitive gloves - allows charge to be disturbed

How can a barcode help manage stock (3)

identifies unique product can automatic re-order product can be used to look up product

How digital cameras work (5)

images converted from analogue to digital using ADC image turned to pixels each pixel given value/colour pixels form grid pixels stored in sequence

How DLP screen works (5)

uses tiny mirrors mirrors laid out in grid mirrors tilt towards/away from light source mirrors reflect light towards lens colour produced using colour wheel

Benefit of LCD projector (3)

uses less power higher resolution runs quiter

How optical mouse works (5)

shines LED under mouse light reflects back through lens converted to value value transmitted to computer computer determines direction and speed of movement

How keyboard works (4)

key pushes switch on circuit board completes circuit location of press calculated location corresponds to ASCII value

When does an interrupt occur (3)

paper jam out of ink out of paper

What happens when paper gets jammed in printing process (2)

printing stops interrupt is sent to computer

Examples of output devices (3)

monitor speaker headphones

Examples of input devices (3)

keyboard mouse microphone

What type of device is an actuator (output or input)

output device

LED benefits (3)

consumes less power has bright screen/colours lasts long

Actuator description

operated by signals to cause physical movement

How barcode finds price of product (3)

database stores data barcode value transmitted to database price is found

How LCD works (6)

beam of light generated by a bulb light sent to group of chromatic-coated mirrors mirrors reflect light back at different wavelengths corresponding to RGB 3 different light components pass through 3 LCD screens images combined using prism to create full colour image image passes through projector lens onto a screen

What does LCD stand for

Liquid Crystal Display

How 2D scanner works (5)

paper placed on a glass panel light illuminates document scan head moves across document lens focuses on document image scanned image turned to electric form by CCD

Applications of 2D scanners (3)

airports - read passport OCR software - read text digital camera

How 3D scanners work (3)

object has x,y coordinates scans along coordinates scanned image used by CAD

What do QR codes stand for

quick response codes

How microphone works (3)

diaphragm vibrates producing electric signal signal goes to sound card converted into digital values