Human Factors Criteria for the Design and Acquisition of ... - FAA

Keyboards June 20049.15 BacklitkeyboardsBacklit keyboards are designed for low ambient lightconditions where a standard keyboard cannot be used.The backlighting generally uses LED technology toilluminate the keys on the keyboard, to allow the user tooperate the keyboard in varying ambient lightingconditions. Backlit keyboards are often found in publicsafety, mobile, and control room applications.Due to the fact that backlit keyboards are not common inmost office work environments, there is a lack ofresearch on the design of backlit keyboards. The FederalAviation Administration (FAA) does use backlitkeyboards in several operational environments. Thefollowing guidelines are derived from a study conductedon backlit keyboards for the FAA.9.15.1 Leakage of light between keys. Leakage of lightbetween the keys of backlit keyboards should beminimized. [Source: Ahlstrom, 1998]9.15.2 Even illumination. The entire character on backlitkeyboards should be evenly illuminated to facilitatecharacter identification. [Source: Ahlstrom, 1998]9.15.3 Location of brightness control. The brightnesscontrol knob should be placed in a location that is easilyaccessible without getting in the way of operations, butwill not be inadvertently activated. [Source: Ahlstrom, 1998]9.15.4 Activation of brightness control. The brightnesscontrol knob or dial should increase brightness whenrotated clockwise or to the right and decrease brightnesswhen rotated counterclockwise or to the left. [Source:NUREG 0700, 2002]9.15.5 Location of on/off switch. The on/off switchshould be placed in a location that is easily accessiblewithout getting in the way of operations, but will not beinadvertently activated. [Source: Ahlstrom, 1998]9.15.6 Color of backlighting. Where possible, backlitkeyboards should use white backlit characters on blackkeys. [Source: Ahlstrom, 1998]9-39