Input Devices (CIE IGCSE Computer Science)

• Every computer system receives commands and data, from the real world, via input devices
• Input devices converts inputs into digital data which can be processed
• For conventional computer systems, such as desktop computers and laptops, the most common input devices are the mouse and the keyboard
• There are a wide range of input devices used in more specialist computer systems such as scanners and sensors

Barcode Scanner

https://vectorportal.com/vector/scanning-a-barcode./21323

Diagram of a barcode being scanned by a handheld barcode scanner

• Barcodes are a series of black and white bars which represent a code
• A barcode reader shines a red laser at the barcode to read the data it represents
• The light from the white lines is reflected back
• Black lines absorb the light so less is reflected
• The different levels of reflection are converted into a binary value which can be processed by a microprocessor
• A barcode reader can be handheld or built into a larger machine such as a self-service checkout at a supermarket
• Barcodes can be used in many ways such as identifying a product being sold or tracking a package through the delivery process
• Benefits include faster checkouts, automated stock control, less chance of error due to manual entry of data, and more detailed tracking information

Digital Camera

• A digital camera works by capturing light and converting it into a digital image
• Light enters the camera through the lens, it reaches an image sensor where it is split into millions of pixels (small squares). Each pixel measures light intensity which is converted into binary and represents a colour. 
• Digital cameras are integrated into smartphones , used in security systems and by professional photographers to create high quality digital images
• An advantage of digital cameras is they show a preview of the image
• They also instantly create an image which can then be easily duplicated and transmitted via bluetooth or WiFi
• Software can be used to edit digital photos, for example applying a filter or retouching a photo

Keyboard

• A keyboard is the most common device used for text-based data input
• They are connected either by a USB cable or wirelessly to the computer system
• They are built into laptops. 
• Smartphones and tablets have virtual keyboards
• Each key on a keyboard has a peg underneath it which makes contact with a conducting membrane. This is then converted into an electrical signal to transmit a unique character code

Microphone

• A computer microphone works by converting sound waves into electrical signals that can be processed by the computer.
• They can capture any real world sound and convert it into digital data which can be stored, duplicated or modified
• The microphone has a diaphragm that vibrates in response to sound waves. These vibrations are then converted into electrical signals by a coil of wire attached to the back of the diaphragm. Changes in the signal are recorded by a microprocessor using a analogue to digital converter
• Microphones are used to record music, telephone calls, communicate online and dictation

Optical Mouse

• A mouse use a laser to detect and track movement, this is then processed by a microprocessor which interprets the movement and replicates it when moving a virtual cursor on-screen
• Items can be selected or moved using the left mouse button, whilst the right button usually displays additional menus
• They can be wired or wireless
• They are used to control the cursor in a Graphical User Interface (GUIs)
• They are simple to use and provide the user with an intuitive way to navigate the computer
• They are reliable due to no moving parts

QR code scanner

https://pixabay.com/vectors/qr-code-scanner-bar-code-156717/

Diagram of a QR code being scanned by a mobile device

• A QR code is a visual representation of data using black and white squares
• QR codes can represent over 7000 digits whereas a barcode represents  up to 30 digits
• QR codes are scanned by a camera (often on a mobile device)
• A piece of software convert the squares into binary data
• QR codes often link to a website where more information can be found
• They can also be used to advertise products, share contact details, provide promotional codes, train tickets, and event tickets

Touchscreen

• A touchscreen can be classed as both an input device and an output device

Types of touch screen

2D and 3D scanners

• A two-dimensional (or flat-bed) scanner shines a strip of light over a document. Reflected light is measured for each pixel. This data is converted into binary data so the document can be digitally recreated
• A three- dimensional laser scanner shines a light over an object. The geometry and dimensions are recorded so the object can be recreated digitally
• The digital 3D model can be modified using specialist software
• A 3D printer could then print out the model
• 2D scanners can be used for creating digital versions of documents or photographs
• Reading passports at airports
• 3D scanners can be used to create 3D models for use with computer-aided design (CAD) software
• Creating replicas with 3D printers
• Typical uses of 3D scanners and printers are dentistry, product development, medical
• A cheap and quick way of creating a digital representation of both 2D and 3D objects so they can be manipulated, stored, transmitted or copied

Summary of input device uses and benefits