In-Depth Notes on Input and Output Devices (Chapter 3)

Hardware Overview

3.2 Input and Output Devices

3.2.1 Input Devices

• Barcode Scanners (Readers)

  • A barcode is a series of dark and light parallel lines with varying thickness.
  • Each number (0-9) is represented by a unique pattern of lines.
  • Guard bars separate the left and right sides of a barcode.
  • Commonly used at supermarket checkouts.

• Advantages for Management

  • Easier and faster to change prices.
  • Better sales information and trends.
  • Reduces the need for pricing every item, saving time and costs.
  • Automatic stock control.
  • Easier monitoring of customer buying habits through loyalty cards.

• Advantages for Customers

  • Faster checkout process; staff don't need to look up prices.
  • Fewer errors in pricing.
  • Itemised bills provided.
  • Potential for savings on costs.
  • Better tracking of 'sell by dates'.

• Quick Response (QR) Codes

  • A matrix of filled dark squares; can hold more information than barcodes.
  • Can store up to 7089 digits vs. 30 digits of barcodes.
  • Used in advertising, website access, storing boarding passes, etc.

• Advantages of QR Codes

  • More information capacity; includes error checking.
  • Easier to read by smartphones, eliminating the need for specialized scanners.
  • Easier transmission as text messages or images.
  • Encryptable for added security.

• Disadvantages of QR Codes

  • Potential for malicious code transmission (attagging).
  • Risk of downloading viruses.
  • May redirect to fraudulent websites.

• Frame QR Codes

  • Enhanced QR codes with advertising logos and graphics embedded.

• Digital Cameras

  • Replace traditional film cameras.
  • Connect via USB or Bluetooth.
  • Features include automatic adjustments to shutter speed, focus, flash, etc.

• Keyboards

  • Common data entry method, connected via USB or wirelessly.
  • Each key corresponds to an ASCII value.
  • Slow entry and prone to errors; ergonomic designs help prevent RSI.

• Microphones

  • Can be built-in or external, connect via USB or Bluetooth.

• Optical Mouse

  • Utilizes tiny cameras, works on various surfaces.

• Benefits Over Mechanical Mouse

  • More reliable (no moving parts).
  • Less susceptible to dirt, no special surface needed.
  • Wired mice avoid signal loss, are cheaper to operate.

• Scanners

  • Two-dimensional (2D) and three-dimensional (3D) scanners exist.

2D Scanners

• Optical Character Recognition (OCR) enables scanned text to be converted into editable formats.
• Used in airports for passport scanning; enhances processing speed and accuracy.

3D Scanners

• Create 3D images of solid objects, used in CAD designs and 3D printing.

Applications of 3D Scanning

• CT Scanners
  • Use Tomography tech to produce images by taking thin 'slices' of objects, stored as digital images.

Touchscreens

• Allow for direct interaction with interfaces through touch.
• Types: Capacitive, Infrared, Resistive.

Capacitive Touch Screens

• Advantages: High durability, clarity in sunlight, multi-touch enabled.
• Disadvantages: Sensitive to electromagnetic fields; works only with fingers or stylus.

Infrared Touch Screens

• Advantages: Multi-touch, resilient to scratches.
• Disadvantages: Prone to false activations from moisture/light interference.

3.2.2 Output Devices

• Actuators

• Control mechanisms (conveyor belts, valves); convert electrical signals to mechanical motion.

• Light Projectors

  • Types include Digital Light Projector (DLP) and LCD projectors.
  • Used for presentations, projecting computer output.

• Printers

  • Inkjet vs Laser:
  • Inkjet: suitable for occasional quality color prints.
  • Laser: high speed for bulk printing, uses dry powder ink, prints entire pages at once.

• 3D Printers

  • Create solid objects layer by layer, applications in prosthetics, aerospace, etc.

• LED and LCD Screens

  • Composition, advantages, and differences highlighted between each type, including aspects such as power consumption, image quality, and technology type.

3.2.3 Sensors

• Definition: Input devices measuring physical properties; must convert analog data to digital using ADC.
• Types of Sensors:
  • Acoustic: measures sound levels.
  • Accelerometer: detects acceleration.
  • Flow: measures fluid movement.
  • Gas: detects gas levels (e.g., carbon monoxide).
  • Humidity: detects moisture levels.
  • Infra-red: measures infrared radiation.
  • Level: detects substance levels.
  • Light: measures ambient light.
  • Magnetic Field: detects changes in magnetic fields.
  • Moisture, pH, Pressure, Proximity, Temperature: all have specific applications in agriculture, environmental monitoring, and security systems.

3.1.5 Embedded Systems

• Definition: Hardware and software combination for specific functions; programmable or non-programmable.
• Examples: Automotive systems, smart appliances, remote-controlled devices, etc.