How many output devices can you name? –Screen (VDU) –Printers (dot-matrix, laser, ink-jet) –Plotter –Speakers –Motors
The VDU Differ by size and resolution How is size measured? How is resolution measured? What are the main types? 17 Inch 1024x768 Pixels This is an old fashioned cathode ray tube (CRT) monitor Modern PCs and Laptops have flat screens with liquid crystal displays (LCD)
Dot Matrix Printers How do these work? The printer contains a ribbon covered in ink which is located in front of the paper The print head has a series of pins that are banged against the ribbon which transfers the ink to the paper Cheap but slow, noisy and poor quality
Ink Jet Printers How do these work? The print head sprays ink onto the paper through a series of nozzles Ink jet printers have good quality images, are cheap but can be slow and expensive to run
Laser Printers How do they work? (1) Drum in printer is negatively charged (2) Laser etches a positively charged image onto the drum (3) Ink powder from the toner cartridge sticks to the positively charged part of the drum (4) Paper passes over the drum and the ink powder transfers to the paper (5) A fuser unit heats the paper and fuses on the ink Laser printers are fast, high quality and quiet BUT complex and expensive
Plotters Some images need to be done on a large scale such as architects plans Plotters have an arm with a pen that passes over the paper
Motors or actuators Motors are powered by electrical signals from the computer Stepper Motors – the motor is moved in a series of tiny steps Servo Motors – The motor moves continuously at high speed
Tasks Use the Internet to find a picture of each of these output devices: –Screen (VDU) –Printers (dot-matrix, laser, ink-jet) –Plotter –Speakers –Motors Write about each device, using what you have learnt from the presentation Extension Exercise: Your friend wishes to buy a printer. Explain which type of printer he should buy and why.