Computers π» | I/O Devices | 3.2 Flashcards
Define input device
A hardware component that allows users to input data or instructions into a computer
Define output device
A hardware component that displays or outputs information from a computer, such as a monitor or a printer
Define barcode
A series of dark and light line of varying thickness used to represent data
What is the purpose of a barcode scanner?
To read and convert the analogue data in a barcode to understandable digital data
Where may a barcode reader be used?
- In checkout at supermarkets
- Libraries
What are the advantages of using barcodes in supermarkets?
For the management:
- Easier and faster to change prices on stock
- More upto date sales information
- No need to price every stock item
- Auto stock control
For the customer:
- Faster checkout queues
- Errorrs in charging customers reduced
- Itemised bill given
- Better track of sell-by dates; fresher food
Define QR code
QR (Quick Response) codes are a matrix of dark and light squares which represent data.
What is used to read a QR code?
A phone camera
What are some uses of QR codes?
- Advertising products
- Giving automatic access to a website / telephone number
- Storing boarding passes electronically at airports / train stations
What are the advantages of QR codes opposed to traditional barcodes?
- Holds more information
- Fewer errors: built in error checking
- Easier to read
- Encryptable
What are the disadvantages of QR codes opposed to traditional barcodes?
- More than one format available
- Can transmit malicious code
How do frame QR codes differ from traditional QR codes?
An image can be displayed in the centre for marketing
What is a digital camera?
A camera that does not need film, producing digital images
What automatic tasks can a digital camera carry out?
- Adjusting shutter speed
- Focusing image
- Operating flash
- Changing aperture
- Adjusting size
- Removing red eye
Define ADC
Analouge to Digital Converter
A device which converts analogue data to a form understood by the computer
Define DAC
A device which converts digital data into electrical currents that can drive actuators
What is the purpose of keyboards?
To enter text on computers, tablets, phonesβ¦
A keyboard can be either ___
Virtual or physical
Define virtual keyboard
An onscreen keyboard which uses the featres of the touchscreen to emulate a physical keyboard
Each keyboard character has a β¦
Corresponding ASCII value
What is the purpose of a microphone?
To convert sound waves to an electric current
What may microphones be used for?
Videocalling, recording music, singing, etc.
Define optical mouse
A pointing device that uses a red LED to track the movement of an onscreen cursor or allows for onscreen selection by clicking a button on the device
What are the benefits of optical mice over mechanical mice?
- No moving parts
- Dirt cant get trapped
- No need for special surfaces
What are the two types of scanners?
2D scanners and 3D scanners
What is the purpose of a 2D scanner?
To input hard copy (paper) documents into electronic form in a computer
Define OCR
Optical character recognition:
Technology that can convert hard copy text and images to digital format stored in a computer
Define OMR
Optical mark recognition:
Technology that can recognise marks on a hard copy and store the counts in digital format on a computer
What is the purpose of 3D scanners?
To scan solid objects and produce a 3D image
Define CAD
And what does it stand for?
Computer Aided Design
Software used to create drawings. 3D scanned images are often used in it.
What could some of the uses of 3D scanners be?
- CAD design
- 3D printing
- CT scanning
How can 2D scanning be used in airports?
- Reading passports
- Using OCR to represent passport pages in ASCII
- Storing passport faces for facial recognition
Define touch screen
A screen which allows the user to select or manipulate a screen image using the touch of a finger or stylus
What are the 3 types of touch screens?
Resistive, Capacitive, and Infrared
Where are touch screens often found?
- Mobile phones
- Tablets
- Fast food selectors
Define capacitive touch screen
A type of touch screen that uses the change in the screenβs capacitance when it is touched by a finger or stylus
Define resistive touch screen
A type of touch screen that uses two conductive layers which make contuct where the screen is touched
Define infrared touch screen
A type of touch screen that uses infrared beams and sensors to detect where the screen is touched
What are the advantages of capacitive touch screens?
- Better image clarity than resistive screens
- Very durable
- Projective touch screens allows for multi touch
What are the disadvantages of capacitive touch screens?
- Surface capacitive touch screens only work with bare fingers or a stylus
- Sensitive to EM radiation
What are the advantages of infrared touch screens?
- Allows for multi touch
- Good durability of screen
- Operability not affected by scratched or broken screen
What are the disadvantages of infrared touch screens?
- The screen can be water or moisture sensitive
- Possible for accidental activationt o take place
- Sensitive to light interference
What are the advantages of resistive touch screens?
- Good resistance to dust and water
- Can be used with bare fingers, stylus and gloved hand
What are the disadvantages of resistive touch screens?
- Low touch sensitivity (sometimes have to press down harder)
- Doesnβt support multi-touch facility
- Poor visibility in strong sunlight
- Vulnerable to scratches on the screen (made of polymer)
What are the disadvantages of resistive touch screens?
- Low touch sensitivity
- Doesnt support multi touch
- Poor visibility in strong sunlight
- Vulnerable to screen scratches
Define actuator
An output device which converts electrical energy to mechanical movement
Define DLP projector
Digital Light Projector
A projector making use of micromirrors that tilt towards a light source in differing ways
Define LCD projector
Aprojector making use of a high intensity beam of light that passes through an LCD display
What are the advantages of DLP projectors?
- Higher contrast ratios
- Higher reliability
- Quieter running
- Smaller and lighter than LCD projectors
What are the disadvantages of DLP projectors?
- Image tends to suffer from βshadowsβ when showing movement
- No grey components in image
- Color definitition not as good as LCD projectors due to lower color saturation
What are the advantages of LCD projectors?
- Gives a sharper image
- Better color saturation
- More efficient in energy use
What are the disadvantages of LCD projectors?
- Contrast ratios not as good as DLPs
- Limited lifespan
- More organic so they degrade over time
What are the two types of printers?
Inkjet printers and laser printers
When are inkjet printers used?
For printing one off photos where only a few pages of good quality, color printing is needed
When are laser printers used?
When high quality fast prints inn high voolume are needed
What are 3D printers used for?
To produce solid objects that actually work, created using materials
What are some uses of 3D printing?
- Covering prosthetic limbs to exactly fit the limb
- Making items to allow precision reconstructive surgery
- Making lightweight wings in aerospace
- Fashion and art
- Making parts for items no longer in production
What is an LED screen?
A screen made up of tiny Light Emitting Diodes, each LED being either red, green, or blue
What is an LCD screen?
A screen made up of tiny liquid crystals that make up an array of pixels, backlit by a ligh source
An LCD screen can be backlit by either a β¦ or a β¦
LED screen, or a CCFL
Where are LED screens often used?
In large outdoor displays due to brilliance of colours.
What does OLED stand for?
Organic Light Emitting Diodes
How does OLED differ from LED in functionality?
They do not require a backlight as it is a self contained system
What are CCFLs made up of?
Two fluorescent tubes behind the LCD screen
What are the advantages of LEDs?
- Reach max brightness almost immediately
- Give of a white light rather than yellowish light in CCFL
- Monitors can be thin
- Lasts indefinitely
- Consume little power
What are the advantages of OLEDs?
- Lighter
- Gives off brighter light
- No need of backlighting
- Allows for βblacker blacksβ
What is a speaker?
An output device that converts electrical currents into sound produced
Define sensor
Input devices which read or measure physical properties from their surroundings
Why does a sensorβs data have to pass through an ADC?
Sensors measure physical quantities in analogue form, which cannot be understood by a computer and has to be converted into digital form.
Purpose
Temperature sensor
Measure temperatuure of the surroundings
Example applications
Temperature sensor
- Control of a central heating system
- Controlling a chemical process
- Monitoring temperatures in greenhouse
Purpose
Moisture sensor
Measures water level in a substance
Example applications
Moisture sensor
- Controlling moisture levels of soil in greenhouse
- Monitoring moisture levels in food processing factory
Purpose
Humidity sensor
Measures amount of water vapor in a sample
Example applications
Humidity sensor
- Monitor humidity levels in building
- Monitor humidity levels in microchip factory
- Monitor humidity levels in greenhouse air
Purpose
Light sensor
Using photoelectric cells to produce an output depending on the brightness of light
Example applications
Light sensor
- Switching street lights on and off depending on light levels
- Switching on car headlights automatically when dark
What are the two types of infrared sensors?
Active and passive
Purpose
Infrared (active) sensor
Monitoring whether invisible beam of infrared radiation is broken
Example applications
Infrared (active) sensor
- Security alarm systems
- Turning on car windscreen wipers automatically
Purpose
Infrared (passive) sensor
Measures the heat radiation given off by an object
Example applications
Infrared (passive) sensor
- Security alarm system
- Monitoring temperature inside industrial freezer
Purpose
Pressure sensor
Generating different electric currents depending on pressure applied
Example applications
Pressure sensor
- Weighing of lorries at weighing station
- Measuring gas pressure in nuclear reactor
Purpose
Acoustic / sound sensor
Converting detected sound into electrical signals
Example applications
Acoustic / sound sensor
- Picking up noise of footsteps in a security system
- Detecting sound of liquids dripping at a faulty pipe joint
Purpose
Gas sensor
Detecting gas and producing output depending on level of said gas
Example applications
Gas sensor
- Monitor pollution levels in air in airport
- Monitoring oxygen and carbon dioxide levels in greenhouse
- Monitoring oxygen levels in car exhaust
Purpose
pH sensor
Measuring acidity through changes in voltage
Example applications
pH sensor
- Monitoring acidity levels of soil in greenhouse
- Controlling acidity levels in chemical process
Purpose
Magnetic field sensor
Measuring changes in magnetic fields
Example applications
Magnetic field sensor
- Detecting magnetic field changes in mobile phones and CD players
- Used in anti-lock braking systems in cars
Purpose
Accelerometer
Measuring acceleration and motion of an application
Example applications
Accelerometer
- Measuring rapid deceleration and applying air bags in cars
- Changing between portrait and landscape mode in mobile phones
Purpose
Proximity sensor
Detecting the presence of a nearby object
Example application
Proximity sensor
- Burglar alarm system
- Detecting when face or ear is close to mobile phone
Purpose
Flow (rate) sensor
Measuring the flow rate of moving liquid or gas and producing an output based on the amount of liquid or gas passing over the sensor
Example applications
Flow (rate) sensor
- Respiratory devices and inhalers in hospitals
- Measuring gas flows in pipes
Purpose
Level sensor
Using ultrasonics or conductivity to measure changing liquid levels
Example applications
Level sensor
- Monitoring petrol tank levels in car
- In pharmaceutical process where powder levels in tablet production is monitored
- Leak detection in refridgeran (AC)
