Interaction Devices:
Input Devices
Lecture 11
Date: 9th March
1
Overview of Lecture
•General introduction to input/output devices
•Input Devices
•Text entry devices
•Keyboards
•Handwriting Recognition
•Speech Recognition
•Positioning and pointing devices
•Direct control devices
•Indirect control devices
•Devices for disabled
•Output Devices
2
Interaction Device Introduction
An early input/output device: ASR33 teletype :
3
Interaction Device Introduction
• Screen, or monitor, on which there are windows
• Keyboard
• Mouse/trackpad
window 1
• Variations
• desktop
• laptop
• PDA
window 2
12-37pm
The devices dictate the styles of interaction that the system
supports
If we use different devices, then the interface will support a
different style of interaction
4
Interaction Device Introduction
•Cannot separate interface function from I/O
interaction devices.
•Majority of current interfaces designed to
operate with keyboard and mouse.
•New interaction styles and devices are
required to support inputs such as voice input,
gesture recognition, 3-D pointing, haptic
interaction, wearable computers.
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Interaction Device Introduction
•Devices should be easy and pleasant to use,
fast to learn, with minimal effort and error.
They generally involve physical actions of
dragging, clicking, typing, speaking, writing,
etc.
•Different devices have different affordances,
and differing capacity for accuracy and
feedback.
•Also need to consider issues such as fatigue
and long term health effects.
6
Interaction Device Introduction
Interaction
Devices
Input
Devices
Output
Devices
7
Input Devices
•
An input device is a device that, together with
appropriate software, transforms information
from the user into data that a computer
application can process
•
Input devices can be categorised into
•
•
•
•
Text entry devices
Positioning and pointing devices
Devices that input pictures
Devices that input Sound
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Text-Entry Devices
•
•
Keyboards
Other text-entry devices
Text-Entry Devices
9
Keyboards
• Most common input method
• Discrete entry device (I.e. involves sensing one of
two or more positions)
• Physical design of keys and key groupings should
be considered
• A key-press closes a connection, causing a
character code to be sent to the computer
• Connection is usually via a lead, but can be wireless
Text-Entry Devices
10
Keyboards
Keyboards Types:
•
QWERTY
•
Alphabetic
•
Chord
•
Dvorak
•
Braille
•
Mobile Phone Keyboard
Text-Entry Devices
11
QWERTY Keyboards
2
1
Q
4
3
W
E
S
A
Z
5
R
D
X
6
C
T
F
Y
G
V
8
7
U
H
B
N
9
I
J
M
0
O
K
P
L
,
.
SPACE
•Named from topmost left letters
•Most common keyboard
•Based on typewriter key layout design – designed to
prevent jamming of the keys
•Not optimal for typing – frequently used letters placed
far apart thereby increasing finger travel distances
•Cost of replacement perpetuates use
Text-Entry Devices
12
Alphabetic Keyboards
•Keys arranged in alphabetic order
•not faster for trained typists
•not faster for beginners either
•No inherent advantage
•Sometimes used in personal organisers
Text-Entry Devices
13
Chord Keyboards
Only a few keys - four or 5
•Letters typed as combination of key-presses
•Compact size - ideal for portable
applications
•One handed use
•Short learning time
•Fast
•But fatigue after extended use
•Sample use – transcript recording in court
Text-Entry Devices
14
Dvorak Keyboards
•common letters under dominant fingers
•biased towards right hand
•common combinations of letters alternate between hands
•10-15% improvement in speed and reduction in fatigue
•But - large social base of QWERTY typists produce market
pressures not to change
Text-Entry Devices
15
Braille Keyboards
• Keyboard especially adapted to blind or visually
impaired users
• Keys are embossed to enable identification of keys
• Frequently used with “voice output” systems
Text-Entry Devices
16
Mobile Phone Keyboards
• use numeric keys with
multiple presses
•
•
•
•
2–abc6-mno
3-def 7-pqrs
4-ghi 8-tuv
5-jkl 9-wxyz
• hello = 4433555[pause]555666
• surprisingly fast!
• T9 predictive entry
•
•
•
•
type as if single key for each letter
use dictionary to ‘guess’ the right word
hello = 43556 …
but 26 -> menu ‘am’ or ‘an’
Text-Entry Devices
17
Other Text Entry Devices
Handwriting recognition
•
Handwritten text is input into the computer, using a special
pen and typically, a small notebook sized computer with a
screen that the user can write directly onto.
•
Attractive as a text entry method because handwriting is a
common familiar activity
•
Handwriting recognition software translates handwritten
characters into ASCII text that can be displayed instantly on
screen as printed characters
•
Handheld organizers – Apple Newton (the first), Psion, Palm,
PocketPC (from Microsoft)
Text-Entry Devices
18
Speech Recognition
•Speech recognition technology replaces a computer
keyboard with a microphone and software to change the
spoken word into typed characters
•Natural form of communication, easier to train new users
than other input devices
•Does not require hands or other limbs – operators can
carry out other actions
•Offers disabled people (particularly blind, motor
impairment) the opportunities to use new technology
•Limited by recognition error rate of speech recognition
systems
•Variety of accents and intonations increase error rate
•External noise interfering
Text-Entry Devices
19
Speech Recognition
Primary components of a speech recognition system:
1. Speech capture device = Microphone and associated
analog-to-digital converter that digitally encodes the
speech waveform
2. Digital signal processing module – detects word
boundaries and separates useful speech information other
unimportant data
3. Specialised speech recognition software, incorporating
reference speech patterns, and pattern matching
algorithms
Text-Entry Devices
20
Speech Recognition
Speech recognition systems can be categorised by
number of users:
•
Speaker-dependent system require each user to train a
system to recognise their voice
•
Speaker-independent systems try to accommodate a
large range of speaking characteristics and vocabulary
Text-Entry Devices
21
Positioning & Pointing Devices
Pointing devices are applicable in six types of interaction
tasks:
1. Select:
•user chooses from a set of items.
•used for traditional menu selection, identification of a file in a directory,
or marking of a part in an automobile design.
2. Position:
•user chooses a point in a one-, two-, three-, or higher-dimensional space
•used to create a drawing, to place a new window, or to drag a block of
text in a figure.
3. Orient:
•user chooses a direction in a two-, three-, or higher-dimensional space.
•direction may simply rotate a symbol on the screen, indicate a direction
of motion for a space ship, or control the operation of a robot arm.
Positioning & Pointing Devices
22
Positioning & Pointing Devices
4. Path:
•user rapidly performs a series of position and orient operations.
•may be realized as a curving line in a drawing program, the instructions
for a cloth cutting machine, or the route on a map.
5. Quantify:
•user specifies a numeric value.
•usually a one-dimensional selection of integer or real values to set
parameters, such as the page number in a document, the velocity of a
ship, or the amplitude of a sound.
•6. Text:
•user enters, moves, and edits text in a two-dimensional space. The
•pointing device indicates the location of an insertion, deletion, or change.
•more elaborate tasks, such as centering; margin setting; font sizes;
highlighting, such as boldface or underscore; and page layout.
Positioning & Pointing Devices
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Positioning & Pointing Devices
•
Pointing devices are generally fast and
easy to use, but require hand-eye
coordination.
•
Can be divided into:
•
•
•
direct control devices
indirect control devices
devices for disabled
Positioning & Pointing Devices
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Positioning & Pointing Devices
General Devices
Indirect pointing device
•
•
•
•
Mouse
Trackball
Joystick
Touchpad
Direct control pointing device
•
•
Touch-Sensitive screens
Light Pen
Devices for the Disabled
• Eyegaze device
• Eye Typer
• Head movement tracker
Positioning & Pointing Devices
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Positioning & Pointing Devices
Indirect Pointing Devices – Mouse
•
•
•
•
Requires physical space for movement
Provides relative motion
Can be difficult for novice users (indirect
mapping)
Two characteristics: planar movement, and
buttons
Positioning & Pointing Devices
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Positioning & Pointing Devices
Indirect Pointing Devices – Trackball
•
•
•
•
Weighted ball is rotated inside a static
housing
Compact -> Good for limited space
situations – e.g. laptops
Difficult for long movements
Requires separate buttons for select
Positioning & Pointing Devices
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Positioning & Pointing Devices
Indirect Pointing Devices – Joystick
•
•
•
•
•
•
Usually used for tasks incorporating direction
and speed rather than location
Compact - requires very little space
Compact, must be stable
Absolute (movement) and isometric (direction
and velocity)
Inexpensive and robust
Often found in computer games
Positioning & Pointing Devices
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Positioning & Pointing Devices
Indirect Pointing Devices – Touchpad
•
•
•
Typically used in portable computers to
replace mouse
+ requires minimal space (typically 2-3
inches in size
- can be difficult and inaccurate to use
Positioning & Pointing Devices
29
Positioning & Pointing Devices
Direct Control Pointing Devices – Touch
Sensitive Screens
•
•
•
•
•
•
•
allows direct control touches on the screen using
a finger
lift-off strategy enables users to point at a single
pixel
the users touch the surface
then see a cursor that they can drag around on
the display
when the users are satisfied with the position,
they lift their fingers off the display to activate
can produce varied displays to suit the task
are fabricated integrally with display surfaces
Positioning & Pointing Devices
30
Positioning & Pointing Devices
Direct Control Pointing Devices – Light Pens
•
•
•
•
enabled users to point to a spot on a screen
and to perform a select, position, or other task
it allows direct control by pointing to a spot
on the display
incorporates a button for the user to press
when the cursor is resting on the desired spot
on the screen
Disadvantages:
•
•
•
users' hands obscured part of the screen,
users had to remove their hands from the keyboard,
users had to pick up the lightpen
Positioning & Pointing Devices
31
Positioning & Pointing Devices
Devices for Disabled – EyeGaze Device
• An eyegaze unit is worn on a headband
on the users head - screen cursor is
driven by users eye movements
• + good for disabled users with motor
impairments or any environment where
user is limited in movement
+ Fast
+ accurate
- Expensive
- Good for selection, but not for continuous movement
of cursor
Positioning & Pointing Devices
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Positioning & Pointing Devices
Devices for Disabled – Eye Typer Device
• Developed for users with severe motor
impairment
• The user “types” by scanning the
keyboard and fixing momentarily on each
character that is wanted
• The characters are displayed on a panel
in qwerty keyboard layout. Each
character has a light embedded in it. The
display has a camera that can detect
which character the user is looking at.
Positioning & Pointing Devices
33
Positioning & Pointing Devices
Devices for Disabled – Head Movement
Tracker
• Developed for users with severe motor
impairment
• The user wears a lightweight headset.
The “keyboard” is a display on the
screen. The system detects slight
movements of the user’s head to move
cursor. To operate a key, user moves
cursor to the key and blows on a blow
switch
Positioning & Pointing Devices
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Other Device Types
•
Picture Entry devices
•
•
•
•
Scanners
Video cameras
MPEG camera
Sound entry devices
•
Microphone
Positioning & Pointing Devices
35
Summary of Lecture
•Input Devices
•Text entry devices
•Keyboards – QWERTY, Alphabetic, Chord, Dvorak, Braille
•Handwriting Recognition
•Speech Recognition
•Positioning and pointing devices
•Direct control devices
•Mouse
•Trackball
•Joystick
•Touchpad
•Indirect control devices
•Touch-Sensitive screens
•Light Pen
•Devices for disabled - Eyegaze device, Eye Typer, Head
movement tracker
References
36
Terms of Reference
• Shneiderman, B. & Plaisant, C. (2005)
Designing the User Interface
• Preece, J. et al. (2002) Interaction Design
• Benyon, D. et al (2005) Designing
Interactive Systems
• Helander, M. et al (1997) Handbook of
Human-Computer Interaction
• Norman, D. (1990) The Design of Everyday
Things
References
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