3.2 Input and output devices

Input Devices

An input device is a piece of hardware that is used to enter data into a computer or device. Input devices are usually categorized as either manual or automatic.

Barcode scanner

• Barcode: A sequence of light and dark parallel lines with varying thickness
• Applications: Supershops, Library, Tickets, Warehouses
• Advantage:
  • The process of data entry is fast and accurate.
  • Bar codes can be printed by normal printing methods.
• Disadvantage:
  • Only numbers can be coded.
  • May be misread if there is any dirt or mark on the code

QR code scanner

• Reads a QR Code to access stored information
• QR: Consists of a grid filled with dark squares on a white background
• Applications: Tickets, Advertisements, WiFi, Business Card
• You can find an example of a QR code in the back cover
• Advantages:
  • Stores more information than barcode
  • Easy way to send mobile users to online content
  • Relatively small in size
  • The scanner (camera) does not have to be lined-up in a specific manner to read
• Disadvantage:
  • Users must be equipped with a camera phone and the correct reader software that can scan the image of the QR Code
  • The transfer of data between two devices can always lead to security issues.

Digital camera

• Captures photos and videos in digital format
• Generates high-quality visual output
• Applications: Photography, Smartphones, Webcams

Keyboard

• Inputs text and commands by pressing keys
• Found in Computers, Laptops, Tablets or other devices
• Applications: Data Entry, Documents, Using Software

Microphone

• Used to capture and input sound into a device by converting it to digital
• Found in modern smartphones, computers, Recording studios
• Applications: Voice Communication, Recording Audio

Optical Device

• Controls the on-screen cursor through hand movements on a surface
• Provides accurate navigation and interaction with the computer
• Commonly used with desktop computers and built into laptops

Touch screen

2D Scanner

• The hard copy document or image converted into an electronic form for storing, editing, or sharing
• Optical Character Recognition (OCR): Software converting scanned documents into a text file format
• If scanned document is a photo, an image file is produced
• Applications: Hard copy scanning, Passport Scanning, MCQ Checking in offices, libraries and schools

3D Scanner

• Records precise 3D shapes and measurements of objects
• Generates digital models for design, testing, or replication
• Application: Manufacturing, Design, Medical imaging (eg. CT Scan)

Output Devices

Devices that present data from a computer in a usable form, such as sound, images, or printed text.

Actuator

• A mechanical device or motor which carries out the action or decision made by the control system
• Transforms energy into mechanical motion
• Applications: Robotic arm, Opening valve, Flood barrier gates, Rotating motors

Inkjet printer

• Produces text and images on paper using fine droplets of ink
• More affordable than many other printer types
• Applications: Home, Schools, Offices

Laser printer

• Uses laser heat to fuse toner powder onto paper
• Produces high-quality prints
• Offers fast printing speed
• Applications: Schools, Offices

Liquid crystal display (LCD) screen

• Shows images and videos using liquid crystals illuminated by a backlight
• Applications: Television, Computer Monitors, Smartphones
• Advantages:
  • Low power consumption
  • Runs at cool temperature
  • Bright image/colours
  • High resolution image
  • Cheaper to purchase than LED screen

Light emitting diode (LED) screen

• Shows images and videos using small LED lights
• Applications: Television, Computer Monitors, Smartphones
• Advantages:
  • Reaches maximum brightness quickly
  • Colours are vivid
  • Good colour definition/contrast can be achieved
  • Screens can be thinner/thin
  • More reliable as LED’s are long lasting
  • Consume very little/less energy

Digital light processing (DLP) projector

• Projects images onto a surface
• Displays images or videos using light reflected from tiny mirrors
• Applications: Cinema, Classroom, Large Presentations
• Advantage:
  • Higher contrast ratio
  • High Quality Image
  • Longer Lasting
  • Quieter
  • Smaller and Lighter
  • Better for smoky atmosphere

Liquid crystal display (LCD) projector

• Uses light through liquid crystal panels to project images or videos onto a flat surface
• Advantage:
  • Higher Resolution
  • More accurate color
  • Image usually brighter for same power
  • Cheaper
  • Quieter
  • Any surface can be used as display
  • Produces less heat
  • Longer lasting lamps

Speaker

• Transforms electrical signals into audible sound to play music
• Produces analogue sound from electronic devices
• Applications: TV, Radio, Smartphones

3D printer

• Builds a 3D object by stacking thin layers of plastic
• Creates three-dimensional models layer by layer
• Applications
  • Creating Prototypes
  • Prosthetic limbs made to exactly fit the recipient
  • Items to allow precision reconstructive surgery
  • Custom Parts
  • Making parts for items no longer in production

Control/Monitoring System

Sensors

• Input devices.
• It measures/takes (physical) readings of the surrounding environment which is converted to digital using Analogue to Digital Converter (ADC).
• Factors Determining Quality of Sensors: Accuracy, Range, Resolution
• Sensors should be insensitive to any other physical conditions
• Sensors should not influence the measured property in any way

Monitoring System

• Monitors some state external to the computer system
• No changes were made to the environment by the system, and hence, no feedback

Control System

• Regulates the behavior of other devices or systems
• Event-driven system: The controller alters the system's state in response to some event
• Time-driven system: The controller takes action at a specific point in time
• May use microprocessors: General Purpose, Embedded controller or microcontroller, graphical processing unit (GPU)
• Examples: Automatic doors, heating systems, taxi meters, elevators, washing machines, process control¹, device drivers, domestic robots, GPS systems, traffic lights (Fixed time and dynamic control)

Process of Monitoring/Control

• Sensors send signals to microprocessor
• Analogue signals are converted to digital (using ADC)
• Microprocessor compares value to stored value
• If out of range/matches stored values do one:
  • Microprocessor send signal to cause an action to occur
  • No action taken
• Output/record readings
• Monitoring is continuous

Types of Sensor: