Guidelines

Keypads

Please note: This section of the guidelines focuses mainly on mechanical keys. We also have a section specifically referring to membrane keys.

Consistency in the layout of keypads is essential for blind users and highly desirable for other users. It is also important to set out the keys in a way that makes it easy to distinguish between the main numerical keys and other function keys. Variation in the size, shape and position of function keys will help differentiation.

A standard layout for keypads is essential for blind people. There are currently two common layouts for numeric keys; the telephone layout and the calculator layout. It is recommended that the telephone layout be used exclusively on public access terminals.

Enlarged raised keys enable persons with poor dexterity to press the correct key; a concave shape to the keys will also help fingers to stay in place. However some disabled people prefer convex keys since they can be activated by the hand for those unable to use their fingers. The spacing between the keys is as important as the size of the keys. When a person has difficulty making precise finger movements, large keys that are recessed or guarded can help ensure that the wrong key is not pressed. For many disabled people it is important to be able to connect an external keyboard to suit their specific needs.

On a telephone, speech-input keying is a useful means of providing a hands-free call set-up for users with reliable voice, and may be valuable even where full hands-free operation is not necessary (eg when hand tremor interferes with manual keying). Useful for dyslexic users who can read aloud and simultaneously dial a number thus avoiding short-term memory problems. Such systems could be limited to just the numerals or a few words such as 'doctor' or 'Jane'.

Persons who are blind or have low vision find it useful to be able to feel the keys of a telephone. It is particularly important to have a single raised dot on the number 5 key.

Large clear typefaces should be used to improve legibility for persons with low vision. When choosing typefaces it is important to use characters that have clear 'open' shapes. Many people with low vision can easily misread such characters as 3, 5, 6, 8 and 9 if the tails curl over; this tends to blur or merge the shapes. There is a typeface specifically developed for labelling keys.

Visual markings on the keys should be characters at least 4 mm high and should have good contrast with the colour of the key (eg. white characters on matt black keys). However, on numeric keypads which also include up to 4 alphabetic characters, the size of the alphabetic characters should be as large as possible without affecting the legibility of the numerals (NB for most users, the legibility of the numerals is more important than the legibility of the alphabetic characters); the spacing between the alphabetic characters is as important as the size of the character.

Colour coded keys should be:

Red:	Cancel
Yellow:	Clear or Correct
Green:	Enter or Proceed
Blue:	Help or Information

The standards in various countries differ over the embossed symbols to be used on the function keys.

The most prevalent are:

Controls and keys should be tactually discernible without activating the control or keys. The status of all locking or toggle controls or keys should be visually discernible, and discernible either through touch or sound.

The arrangement of keys
Function keys should be clearly separated from the numeric keys. When command keys are vertically arranged, 'cancel' should be the uppermost key and 'enter' the lowest. When the command keys are horizontally arranged, 'cancel' should be located the furthest left, 'enter' the furthest right. It is better to position the command keys to the right of the numeric keys. They are then less likely to be inadvertently touched when entering numerals. Where command keys are positioned beneath the numerical keys they may pose a problem to visually impaired persons because they are likely to be pressed accidentally when entering numbers. Command keys should be as large as possible so that the words on them can be larger and thus easier to read.

Shaped keys
Colour should not be the only distinguishing feature between keys, since red/green colour blindness is not uncommon; if possible, the keys should have different shapes and be marked with symbols.

Internal illumination: keypad is waiting for input
Ideally keys should be internally illuminated when the terminal is waiting for input from that keypad.

Internal illumination: visual benefit
Results of a study into the benefit of internal illumination reveal that a benefit exists in lower ambient lighting conditions, such as a shaded cash machine, an indoor ticket machine, an underground car park, or a covered petrol station, where artificial lighting may be low or non-existent. In contrast, in bright ambient lighting, a slight disadvantage to having internal illumination was revealed (when compared to a non-illuminated keypad with white text on black keys). The darker the ambient lighting, the more beneficial internal illumination of keys will be.

Sound
Auditory feedback in the form of sounds such as a 'beep' or 'click' when a key is pressed is helpful to many people and enhances feedback and subsequently performance.

Tactile feedback
Tactile indication can be provided by a gradual increase in the force, followed by a sharp decrease in the force required to actuate the key, and a subsequent increase in force beyond this point for cushioning.

More time
Many elderly people and those with a cognitive impairment do not like to be rushed or to think that they are likely to be 'timed out' by the machine, so it is necessary to allow for such people to use the terminal at their own pace; this requirement could be stored on the user's card.

Privacy
Keypads are often used in security context, therefore they often need to be hidden from the view of others. This can be achieved by the addition of a privacy shield. Since the principle purpose of a privacy shield is to block the keys from view, this can pose serious problems with respect to accessibility, both visually and physically. Our section on privacy shields provides further information on these accessibility issues.

Checklist for Keys

Recommendations

The following are drawn from other guidelines but the scientific data on which they are based are not quoted:

Relevant standards

Further information