Input Devices, Output Devices, Sensors, and Control Systems

Comprehensive vocabulary flashcards covering hardware input devices, touch screen technologies, scanning equipment, sensors, microprocessor control loops, output displays, and printing systems.

Input Device

A hardware device that sends data and signals into a computer for processing.

Output Device

A hardware device that presents or outputs processed data from a computer to the user.

Keyboard

A manual input device where pressing a key completes an electrical circuit, allowing a processor to identify the pressed key and look up its character code (e.g. ASCII) to send to the computer.

Optical Mouse

A pointing input device that shines a red LED onto a surface while a CMOS sensor captures thousands of images per second, which a processor compares to calculate movement speed and direction.

Microphone

An input device in which incoming sound waves vibrate a diaphragm, moving a coil within a magnetic field to induce an electrical current that an ADC converts to digital data.

Resistive Touch Screen

A touch screen composed of two flexible layers separated by a gap; pressing the screen brings the layers into contact to complete a circuit and determine the touch location. It is cheap and works with gloves or a stylus, but has poor clarity and supports only single touch.

Capacitive Touch Screen

A touch screen featuring a glass layer that maintains an electric field; contact from an electrical conductor (such as a bare finger) alters the electrostatic charge, allowing sensors to calculate the coordinates. It supports multi-touch and is clear and durable, but cannot be operated with standard gloves or non-conductive pens.

Infra-red Touch Screen

A touch screen that projects an invisible grid of infrared light beams across the display surface; touching the screen interrupts specific beams, enabling sensors to locate the touch position. It supports multi-touch and works with any object, but is expensive and vulnerable to dirt or bright light.

Barcode Scanner

An optical input device that casts a red laser or LED beam across alternating bars and spaces; black bars absorb light while white spaces reflect it back to a sensor, which translates the pattern into a numeric code looked up in a database.

QR Code Scanner

An optical input device that uses a digital camera to capture a 2D matrix code, using three distinct corner squares to establish position and orientation, capable of holding significantly more data than a standard linear barcode.

2D Scanner

An input device that illuminates a flat document on a glass platen, using mirrors and a lens to direct reflected light onto a Charge-Coupled Device (CCD) to produce a digital bitmap image.

3D Scanner

A device that directs lasers or light at a physical object from multiple angles, recording thousands of spatial coordinates to generate a digital 3D model for applications such as CAD or 3D printing.

Digital Camera

An image capture device where light enters through a lens assembly onto an image sensor (CCD or CMOS) comprising millions of photosensitive pixels, each converting photons into electrical signals that form a digital image.

Sensor

A hardware device that detects and measures physical properties or environmental phenomena and converts them into electrical signals; it only collects and transmits data and makes no autonomous decisions.

Acoustic Sensor

A sensor that detects sound levels, commonly deployed in security systems to detect the acoustic signature of shattering glass.

Accelerometer

A sensor that measures acceleration forces and physical tilt, commonly used in smartphones for automatic screen rotation and in vehicles to trigger airbag deployment.

Flow Sensor

A sensor that measures the movement rate or volume displacement of liquids or gases passing through conduits, such as water mains and fuel lines.

Gas Sensor

A sensor designed to detect and measure the concentration of specific gases within an environment, such as carbon monoxide in domestic safety alarms.

Humidity Sensor

A sensor that measures the amount of water vapour present in the ambient atmosphere, frequently utilized in greenhouses and museum exhibition rooms.

Infra-red Sensor

A sensor that detects thermal emissions and kinetic movement, commonly utilized in burglar alarm systems and automatic sliding doors.

Level Sensor

A sensor that monitors and calculates how full a fluid or granular container is, such as storage tanks for vehicle fuel or municipal water.

Light Sensor

A sensor that measures ambient luminous intensity, commonly deployed to automate street illumination and adjust mobile device display brightness.

Magnetic Field Sensor

A sensor that detects and quantifies the direction and strength of magnetic fields, utilized in digital smartphone compasses and automotive anti-lock braking systems (ABS).

Moisture Sensor

A sensor configured to measure the moisture or liquid water content bound inside solid materials, such as agricultural soil inside a greenhouse.

pH Sensor

An analytical sensor that determines the relative acidity or alkalinity of an aqueous solution, commonly applied in testing agricultural soils, aquariums, and river ecosystems.

Pressure Sensor

A sensor that quantifies physical force, load, or weight applied per unit area, used in vehicle tyre pressure monitoring systems and intrusion floor alarm pads.

Proximity Sensor

A sensor that calculates the spatial distance between itself and nearby physical objects without mechanical contact, commonly implemented in automotive parking assist sensors.

Temperature Sensor

A sensor that measures thermal energy or heat, used for thermal regulation in domestic central heating installations and cooking ovens.

ADC (Analogue-to-Digital Converter)

An electronic component that samples continuous analogue electrical signals produced by sensors or microphones and converts them into discrete digital binary data readable by a microprocessor.

Microprocessor (in Control Systems)

The central processing unit that receives digitized sensor readings, compares them against stored target preset parameters, and determines whether an instruction signal must be transmitted to an actuator.

Actuator

An electromechanical output device that converts an electrical control signal from a microprocessor into physical mechanical motion, such as operating motors, opening valves, or running pumps.

Monitoring System

An automated system that measures, records, and displays physical parameters or sounds warning alerts without making autonomous physical changes to the monitored environment (e.g. a patient vital signs monitor).

Control System

An automated feedback system that measures environmental conditions using sensors, compares data against presets with a microprocessor, and actively alters environmental parameters using actuators.

LCD Screen

A flat-panel display technology where liquid crystal molecules untwist or twist to selectively block or transmit light emitted from an LED backlight, passing through red, green, and blue colour sub-pixel filters.

LED Screen

A display panel where every individual pixel is composed directly of tiny discrete red, green, and blue light-emitting diodes, providing high luminance suitable for large outdoor video walls.

Speaker

An electroacoustic output transducer where a DAC translates digital audio data into an analogue electrical current passed through a voice coil, generating a fluctuating magnetic field that vibrates a cone to produce audible sound waves.

LCD Projector

A display projection system that directs intense white light through three individual primary-colour LCD panels (red, green, and blue), recombines the resulting monochromatic images using a dichroic prism, and projects them through a focusing lens.

DLP Projector

A digital light projection system incorporating a Digital Micromirror Device (DMD) microchip covered in millions of microscopic tilting mirrors, using rapid mirror switching and a synchronised spinning colour wheel to project full-colour pixels.

Inkjet Printer

A non-impact printer that stores data in a temporary print buffer and propels microscopic droplets of liquid ink across paper via a print head utilizing thermal bubbles or piezoelectric crystals while a stepper motor advances the sheet.

Laser Printer

An electrophotographic printer that applies an electrostatic charge to a rotating drum, discharges selective areas with a laser beam to create an electrostatic image, coats the latent image with charged dry toner powder, and transfers and fuses it to paper using heat and pressure.

Fuser

A heated pair of rollers in a laser printer that applies thermal energy and mechanical compression to permanently melt and bind dry toner particles into the paper fibres.

3D Printer

An additive manufacturing device that translates a computer-aided design (CAD) model into a three-dimensional physical object by depositing consecutive horizontal layers of molten polymer filament, liquid resin, or powdered metal.