Mice and Trackballs
A common source of trouble for intensive computer users is the mouse used to control the cursor. This has become more serious through the development of software needing its frequent or almost continuous use.
Holding a mouse usually requires gripping between thumb and little finger to move it and then more strongly to hold it in place while the index finger operates the action button. From these actions pains in hand, arm and shoulder can develop. Trackballs, which are inverted mice, are also available in different sizes and mountings, but still need holding and operating by one hand.
All need appreciable hand and arm movement to reach the operating position and they occupy a fair amount of additional desk space. To overcome this problem we have fitted a trackball in the palm rest area of the central number pad. In this position the ball may be easily moved by the thumb with the fingers cupped and the hand resting over the key thumb group. The top of the ball is slightly below the palm rest surface so that it does not interfere with normal keyboard use.
The Keyboard is ergonomically designed for two handed operation, with the central location of the trackball enables either thumb to be used with the wrist kept straight and the hand tilted outwards in a comfortable position. Action Buttons for the trackball are positioned so that they are operated by the other hand. The placing of the buttons allows the hand to rest in a relaxed state but ready for use. This arrangement ensures that the accurate and careful positioning of the ball is not disturbed when operating an action button.