OUTPUT DEVICES Mrs. Ghazaal Igcseict
Ink Jet Printer • Inexpensive to purchase • Easier to move around • Low output volumes • Cartridges need to be changed often • Water-soluble ink
Laser Printer • Very high quality, • Used for high volume output • Used very often in networked environments • Expensive • Toner must be disposed of carefully
Dot Matrix • Impact Printers • Initially developed to replace typewriters • Can work in environments with dirt and oil in the air; noisy industrial environments; • Produce carbon copies • Lowest running cost • More expensive than inkjet printers • Very noisy • Slowest printer
Plotters • Device that works like a printer • Not limited by paper size • Extremely large printouts can be produced • Very high quality • Very slow • Expensive • Filled areas of colours can be difficult to produce
3D Ink Jet Printers • Produces 3D models using layers of resin or plaster • Can create 3D models for CAD (computer-aided design)
Monitors A monitor is a device that displays information from the computer onto the screen The advantage of using a monitor over other forms of output is that the output is immediate The disadvantage is that when the output is changed the previous information is lost from the screen
CRT (Cathode Ray Tube) • They work by an electron gun firing against phosphor particles. • Used in spaces where space is not a problem; also used when more than one user may need to view the screen at the same time (ex. Several designers need to check a prototype) • Advantages • Very cheap (if u can find one to purchase); produces good quality images • Screen can be viewed from a number of angles • Disadvantages • Very bulky, not portable, emit small quantities of radiation • Can have a flickering screen, so prolonged use can cause headaches and eyesight problems
TFT (Thin Film Transistor) • Screen contains thousands of miniature transistors that are activated by the processor (is a kind of LCD) • Used where space is limited, in laptops, and when only one person needs to view the screen at a time. • Advantages • Portable and lightweight, emit less radiation than CRT monitors • Less glare on the screen which makes it more restful on the eye • Disadvantages • Angle at which they can be viewed is limited; there is an inconsistency of colour tones when viewed from different angles • More expensive
LCD (Liquid Crystal Display) • LCD displays utilize two sheets of polarizing material with a liquid crystal solution between them, Each crystal, therefore, is like a shutter, either allowing light to pass through or blocking the light. This shutter along with the others provides the color which you want. • Has almost completely replaced the CRT • Advantages • Portable and lightweight, emit less radiation than CRT monitors • Less glare on the screen which makes it more restful on the eye • Lower power consumption (which makes it ideal for portable devices) • Disadvantages • Angle at which they can be viewed is limited; there is an inconsistency of colour tones when viewed from different angles • More expensive
LED (Light Emitting Diode) • It consists of tiny bulbs which emit light and these bulbs give a more realistic display as compared to others • Laptops, smartphones, tablets, TV’s • Advantages • More realistic colours than LCD, somewhat thinner than LCD • Disadvantages • More expensive
Multimedia Projectors They are the devices that can project an image from a computer on to as large a surface as necessary The only limit to the size of the projection is the power or brightness of the light produced by the projector Disadvantage of using a projector: It relies on a powerful and expensive bulb to provide the pictures. These bulbs are fragile, particularly if the projector is moved while it is still hot.
Speakers Can be directly connected to the computer or inbuilt into the monitor or a laptop. The digital data from the computer is converted into analogue signals by a D/A converter and then amplified and output using the speakers. Required to play sound files attached to multimedia presentations and websites.
Control Output Devices Used to physically change something in response to a command from a computer (processor makes a decision and the control output device carries it out)
What is a control system? • Uses microprocessors or computers to control certain physical conditions • Sensors take measurements, then A/D converter converts them into digital signals • The measurements are compared to stored (predefined/preset) values • Processor makes a decision based on the comparison • Control output devices will be used
Washing Machine Sensors & Actuators Pressure sensor attached to the door checks if the door is shut. Processor uses an actuator to open a valve to let the water in Yes No Temperature sensor senses the temperature of the water Light on the front of the machine goes on to indicate the light is on/ Sometimes Buzzer Heat Water Is it hot enough? No Yes Processor signals for the motor to turn the tub and start the wash