CS 407 Human Computer Interface

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CS 407 Human Computer Interface

• Class 08
• Monday, September 13, 1999

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Thought for the Day

• Expecting the world to treat you fairly
• because you are a good person,
• is like expecting the bull not to attack you
• because you are a vegetarian.

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Project Assignment

• Anyone need the Project 1 Assignment?
• Any questions on Project 1?

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Todays Topics

• Chapter 2, The Computer
• Text Entry devices
• Pointing Positioning devices
• Output devices

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Reading Quiz

• Name two devices for text entry other than the
  keyboard.
• Give one disadvantage of one of the two you named.

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Keyboard types

• Alphabetic
• Sholes / QWERTY
• Dvorak
• Chord

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The Dvorak Keyboard

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Typing Injuries

• Repetitive Stress Injury (RSI)
• Carpal Tunnel Syndrome (CTS)
• Carpal tunnel contains nerves tendons.
• When tendons get irritated, they swell
• and cause nerve problems.
• Typing Injury FAQ http//www.tifaq.org
• Dont ignore symptoms!!!

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Other Text Entry Devices

• Handwriting recognition.
• Problems with
• capturing all useful information - stroke path,
  pressure, etc. in a natural manner
• segmenting joined up writing into individual
  letters
• interpreting individual letters
• coping with different styles of handwriting

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Other Text Entry Devices

• Speech recognition.
• Single user, limited vocabulary.
• Problems with
• External noise interfering.
• Imprecision of pronunciation.
• Accents, head colds, etc.

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Pointing Devices Mouse

• Handheld pointing device
• Very common.
• Easy to use.
• Characteristics
• Planar movement (on desk top).
• Buttons (usually 1 3).
• Requires physical space on desk top.
• Little arm fatigue.

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Mouse Movement

• Mouse movement in (X,Z) plane (desk top)
• Translated to movement in (X,Y) plane (screen)

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Mouse Mechanism

• Two methods for detecting motion
• Mechanical
• Ball turns as mouse is moved.
• Rotates orthogonal potentiometers.
• Can be used on most flat surfaces.

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Mouse Mechanism (2)

• Two methods for detecting motion
• Optical
• LED on bottom of mouse.
• Sits on special gridded pad on desk.
• Less sensitive to dust dirt.
• Useless if it gets off the special pad!

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Rat or Footmouse

• Larger mouse.
• Sits on floor.
• Operated with feet.

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Other Positioning Devices

• Joystick
• Trackball
• Touch screens
• Light pen
• Digitizing tablet
• Cursor keys
• Keymouse (IBM Thinkpad eraser)

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Other Positioning Devices (2)

• Thumb wheels
• Dataglove
• Eyegaze
• Now, the details

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Joystick

• Indirect device.
• Takes up little space on desk.
• Controlled by either
• Movement of joystick
• Distance traveled corresponds to time stick is
  held in a direction.
• Pressure (isometric)
• Speed corresponds to amount of pressure.
• Neither are intuitive.