Page 129 - Handbook of Electronic Assistive Technology

Chapter 5 • Alternative Access Technologies 117

Large Key Keyboards

Large key keyboards are generally the same overall size as standard keyboards, but the
2
2
keys themselves measure around 20 mm compared to approximately 12 mm .
Users with physical support needs or motor coordination difficulties due to, for
example, cerebral palsy, and who have difficulty accurately targeting keys on a standard
keyboard, may be able to use an interface with larger keys, particularly with the addition
of a keyguard (Fig. 5-9). These can also be accessible for users with visual impairments
as they are available with high contrast lettering. Young children or users with visual or
cognitive impairment may benefit from large keyboards with lower case and/or colour-
coded keys.
Large ‘membrane’ or ‘overlay’ keyboards were in common use for many years (e.g., the
British Concept Keyboard and US IntelliKeys), particularly in schools, because the layout
could be altered and programmed to match the user’s needs. Layouts with whole words,
symbols and pictures, or tactile signifiers could also be created. Membrane keyboards
have mostly been superseded by touchscreen devices although the HelpiKeys membrane
at the time of writing is still available and offers QWERTY, alphabetic, numeric and mouse
control layouts, or custom layouts can be designed and printed out.

Mary’s Case Study
Mary attends a mainstream P1 class. She has cerebral palsy, which affects her ability to
hold and use a pencil; she can draw simple lines and shapes, but letter formation is diffi-
cult and slow. She requires assistive technology to write and record, and prefers a compact
keyboard with guard and lower case key stickers.

FIGURE 5-9 Miniature (218 mm × 103 mm), Compact (282 mm × 132 mm) and Jumbo (482 mm × 179 mm) keyboards
with keyguard�