Introduction to Computers Chapter 3

Introduction to Computers

• Course introduction by Dr.Eng. Mahmoud Abu_Alfutuh

Chapter 3: Input and Output Devices

• Covers various input and output devices used in computers.

Lesson 4: Output Devices

• Focuses specifically on output devices.
• Output devices display, convey, or otherwise present information processed by the computer.
• Output translates computer data into a form humans understand.
• Output appears as visuals, sound, or hard copies (printed on paper).
• Examples include monitors, projectors, printers, and speakers.

Output Device Types

• Monitors:

  • Display processed data like images, videos, and text.
  • Also known as Visual Display Units (VDUs).
  • Categorized by technology:
    • CRT (Cathode Ray Tube) Monitors:
      • Electrons fire at phosphor dots on the screen, creating pixels.
      • Color CRTs have red, green, and blue dots per pixel.
      • These dots glow at varying intensities to form color images.
      • Electron guns and magnetic yokes guide electron beams to the screen.
      • Advantages: low cost, bright and clear pictures.
      • Disadvantages: bulky, consume more power.
    • Flat-Panel Monitors:
      • Primarily used in portable computers.
      • Newer types are used on desktops.
      • Higher resolution, take up less space, low power consumption, and run cooler.
      • Flat-panel displays often use LCD (Liquid Crystal Display) technology.
      • LCD types include passive matrix (less expensive, narrow viewing angle) and active matrix (expensive, wider viewing angle and faster refresh).
  • Monitor characteristics for comparison include size, resolution, refresh rate, and dot pitch.

• Projectors:

  • Project computer-generated images on a large screen.

• Sound Systems:

  • Multimedia PCs include microphones, sound cards, and speakers.
  • Sound cards convert digital signals into analog signals for speakers.
  • Speakers convert changing electrical signals to sound.
  • Used for recording and playback through the computer.

• Printers:

• Categorized into:

  • Impact printers (e.g., dot matrix)
  • Non-impact printers (e.g., ink jet, laser).
  • Evaluated based on:
    • Image quality (dots per inch (dpi))
    • Speed (pages per minute or characters per second)
    • Initial cost
    • Cost of operation (supplies)

• Ink Jet Printers:

  • Non-impact printers.
  • Spray tiny ink droplets onto paper.
  • Designed for both color and black/white prints.
  • Relatively inexpensive and have low operating costs.

• Laser Printers:

  • Non-impact printers.
  • Use heat and pressure to bond toner particles to paper.
  • Provide higher image quality.
  • Have higher initial costs, compared to ink-jet printers.

• Plotters:

  • Print large-format designs using mechanical, inkjet, or thermal technologies
  • used for maps, architectural drawings.