Input and Output Devices in Computing

Input device

Any device that allows you to pass information from the outside world into a computer system.

Barcode scanner

Uses a red laser to read a series of black and white stripes.

Digital camera

Captures light via sensors and converts it into a digital image.

Keyboard

Each key is mapped against a character. Key presses are detected, and a signal is sent to the computer.

Optical mouse

Uses a red LED and sensors to determine movement relative to the surface beneath.

Microphone

Vibrations caused by sound waves are captured and converted into a digital representation of sound.

QR code scanner

Read using a camera, processed by an app and converted into readable data.

Touch screens

A popular way of receiving user input, replicates the functions of a mouse.

Resistive touch screen

Consists of two conductive layers separated by an insulating layer.

Capacitive touch screen

Consists of a protective layer, a transparent conductive layer and a glass substrate.

Infra-red touch screen

LEDs shine infrared light to form a matrix over the screen.

2D scanner

Shines a bright line across a document and measures light reflections to create a digital version.

3D scanner

Shines a laser over the surface of an object and captures its geometry and dimensions to create a 3D model.

Output device

Any device that can take data stored in digital form and convert it into another form humans can process such as sound, images or vibrations.

Actuator

Allow physical movements to be carried out, often used in conjunction with a motor and sensor.

Digital light processing (DLP) projector

Millions of micro-mirrors arranged in a matrix grid, placed on a small microchip within the projector itself.

Liquid crystal display (LCD) projector

Uses three separate mirror filters and a prism to create an image.

Inkjet printer

Uses liquid ink forced through fine nozzles.

Laser printer

Uses dry powder fused onto paper using heat.

Liquid crystal display (LCD) screen

Made up of millions of liquid crystals, requires backlighting.

Light-emitting diode (LED) screen

Uses tiny LEDs to produce bright images without the need for additional backlighting.

Speaker

Converts digital representations of sound into analog waves that can be heard by the human ear.

3D printer

Deposits layers of material to build a 3D object.

Sensors

Measure physical properties of the environment and translate the information they collect into a digital form.

Acoustic sensor

Measures sound levels.

Accelerometer

Measures acceleration, vibration, tilt.

Flow sensor

Measures the rate of gas, liquid or powder flow.

Gas sensor

Detects the presence of gas - e.g., carbon monoxide.

Humidity sensor

Measures levels of water vapour.

Infra-red sensor

Detects motion or heat.

Level sensor

Measures liquid levels.

Light sensor

Measures light levels.

Magnetic field sensor

Detects presence and strength of a magnetic field.

Moisture sensor

Measures presence and levels of moisture.

pH sensor

Measures acidity or alkalinity.

Pressure sensor

Measures gas, liquid or physical pressure.

Proximity sensor

Measures distance - e.g., parking sensor.

Temperature sensor

Measures heat levels.