Output Devices

• Inkjet Printers: used to print one-off pictures and documents
• Laser Printers:

  • Used to print flyers, high quality
  • Use dry powder ink (toner) and static electricity to produce text and images
  • Prints the whole page in one go
• Inkjet Printer process:

  • The document describes a process in which data from a document is sent to a printer driver, which ensures it is in the correct format.
  • The driver checks if the printer is available, and the data is stored in a temporary memory.
  • A sheet of paper is fed, and the print head moves across the paper, printing text or image with four ink colors.
  • The printer sends an interrupt to the processor, requesting more data.
• Laser Printer process:

  • The process involves sending data to a printer driver, ensuring it is in the correct format, checking if the printer is available, and then sending the data to the printer.
  • The printer drum is coated with toner, which sticks to the negatively charged parts of the drum.
  • A negatively charged sheet is rolled over the drum, and the toner on the drum produces a copy of the page.
  • The paper then goes through a fuser to melt the ink.
• 3D Printers

  • Used for models of cars
  • Produce solid objects that work
  • Built up layer by layer, using powdered resin, ceramic powder
  • A design is made using Computer-aided Design (CAD)
• 2D and 3D Cutters

  • 3D cutters can recognise objects in x, y, z direction
  • 3D laser cutters can cut; glass, crystal, metal, wood
• Actuators

  • Convert electrical signals to mechanical processes.
  • Used in many control applications involving sensors and devices (ADC and DAC)
• Loudspeakers/Headphones

  • Sound is produced by passing the digital data through a DAC then through an amplifier and then emerges from the loudspeaker
  • Produced by voltage differences vibrating a cone in the speaker at different frequencies
• LCD and LED Monitors

  • The front layer of the monitor is made up of Liquid Crystal Display (LCD)
  • LCD monitors are backlit using Light Emitting Diode (LED) because:
  • LEDs reach their maximum brightness immediately
  • LEDs sharpens image (higher resolution), and CCFL has a yellow tint
  • LEDs improve the colour image
  • Monitors using LED are much thinner than CCFL
  • LEDs consume very little power
  • Before LEDs, LCD monitors were backlit using CCFL
  • CCFL uses two fluorescent tubes behind the LCD screen, which supplies the light source
• Light Projectors:

  • Two common types of light projectors:
  • Digital Light Projector (DLP)
  • LCD Projector
  • Projectors are used to project computer output onto larger screens/interactive whiteboards
• Digital Light Projectors (DLP)

  • Uses millions of micromirrors
  • The number of micromirrors and the way they are arranged on the DLP chip determines the resolution of the image
  • When the micromirrors tilt towards the light source they are on
  • When the micromirrors tilt away from the light source, they are off
  • This creates a light or dark pixel on the projection screen
  • A bright white light source passes through a colour filter on its way to the DLP chip
  • White light splits into primary colours
• LCD Projectors

  • Older technology than DLP
  • A powerful beam of white light is generated from a bulb
  • This beam of light is then sent to a group of chromatic-coated mirrors
  • When the white light hits the mirrors, the reflected light has wavelengths corresponding to red, green, and blue
  • These three different lights pass through three LCD screens
  • When the coloured light passes through the LCD screens, a red, green and blue version of the grey image emerges
  • The image passes through the projector lens onto the screen