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

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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
Keyboards June 20049.15.7 Colored keys. If backlit keyboards use coloredkeys or non-white characters, they should be tested in anenvironment representative of the operationalenvironment to ensure legibility. [Source: Ahlstrom, 1998]9.16Accommodatingpeople withdisabilities9.16.1 Avoiding inadvertent operation. A computer orcomputer system intended to be operable by people withmoderate motor disabilities should provide either ameans for delaying the acceptance of a keystroke for apreset, adjustable amount of time or a keyguard or meansfor mounting a keyguard. [Source: Scadden & Vanderheiden,1988]Additional information. Delaying the acceptance of akeystroke or providing keyguards helps some users whomay otherwise bump and accidentally activate keys otherthan the intended key.Definition. A keyguard is a keyboard cover with holesover keys. [Source: Scadden & Vanderheiden, 1988]9.16.2 Keyguard mounting. Keyboards should bedesigned so that keyguards can be mounted easily.[Source: Scadden & Vanderheiden, 1988]9.16.3 Keyset interlock. Keyboards for users who havefrequent overlap errors in their typing should allow a 100msec keyset interlock to prevent simultaneous activationof two keys. [Source: Trewin, 2002]Additional information. Keyset interlocks keep the keyfrom being triggered until 75 % of its downwarddisplacement has occurred. Their use has been associatedwith an increase in productivity and decrease in errors.Users who have trouble typing without simultaneouslypressing more keys than intended (overlap errors) can behelped by providing a 100 msec keyset interlock withoutslowing their typing time. [Source: Alden, et al., 1972;Klemmer, 1971; Trewin; 2002]9-40
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Page 17 and 18: Keyboards June 20049.2.4 Activity d
Page 19 and 20: Keyboards June 2004e. Pronation/sup
Page 21 and 22: Keyboards June 20049.4 Wrist/Palmre
Page 23 and 24: Keyboards June 20049.5 Keyboardphys
Page 25 and 26: Keyboards June 20049.5.1.6 Keyboard
Page 27 and 28: Keyboards June 20049.5.2 Keyboard l
Page 29 and 30: Keyboards June 20049.5.2.2 Grouping
Page 31 and 32: Keyboards June 20049.6.1 Toggle key
Page 33 and 34: Keyboards June 20049.6.3.5 Consiste
Page 35 and 36: Keyboards June 20049.7 Numerickeypa
Page 37 and 38: Keyboards June 20049.8 Keydimension
Page 39 and 40: Keyboards June 20049.9 Key labeling
Page 41 and 42: Keyboards June 20049.10 Keyactivati
Page 43 and 44: Keyboards June 20049.10.7 Key repea
Page 45 and 46: Keyboards June 2004Exhibit 9.12.b A
Page 47 and 48: Keyboards June 2004Exhibit 9.12.g V
Page 49 and 50: Keyboards June 20049.12.1 Split key
Page 51: Keyboards June 20049.14 Membranekey
Page 55 and 56: Keyboards June 2004GlossaryABC keyb
Page 57 and 58: Keyboards June 2004Homing timeKey f
Page 59 and 60: Keyboards June 2004ReferencesAaras,
Page 61 and 62: Keyboards June 2004Conrad, R., & Lo
Page 63 and 64: Keyboards June 2004Henning, R., Jac
Page 65 and 66: Keyboards June 2004Marteniuk, R. G.
Page 67 and 68: Keyboards June 2004Rempel, D., Bach
Page 69: Keyboards June 2004Swanson, N. G.,

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