Trackball

With most trackballs, operators have to lift their finger, thumb or hand and reposition in on the ball to continue rolling, whereas a mouse would have to be lifted itself and re-positioned. Some trackballs have notably low friction, as well as being made of a dense material such as phenolic resin, so they can be spun to make them coast. The trackball's buttons may be in similar positions to those of a mouse, or configured to suit the user.


Large trackballs are common on CAD workstations for easy precision. Before the advent of the touchpad, small trackballs were common on portable computers (such as the BlackBerry Tour) where there may be no desk space on which to run a mouse. Some small "thumballs" are designed to clip onto the side of the keyboard and have integral buttons with the same function as mouse buttons.

History[edit]

The trackball was invented as part of a post-World War II-era radar plotting system named Comprehensive Display System (CDS) by Ralph Benjamin when working for the British Royal Navy Scientific Service.^[2][3] Benjamin's project used analog computers to calculate the future position of target aircraft based on several initial input points provided by a user with a joystick. Benjamin felt that a more elegant input device was needed and invented a ball tracker^[2][3] system called the roller ball^[2] for this purpose in 1946.^[2][3] The device was patented in 1947,^[2] but only a prototype using a metal ball rolling on two rubber-coated wheels was ever built^[3] and the device was kept as a military secret.^[3] Production versions of the CDS used joysticks.


The CDS system had also been viewed by a number of engineers from Ferranti Canada, who returned to Canada and began development of the Royal Canadian Navy's DATAR system in 1952. Principal designers Tom Cranston, Fred Longstaff and Kenyon Taylor chose the trackball as the primary input, using a standard five-pin bowling ball as the roller. DATAR was similar in concept to Benjamin's display, but used a digital computer to calculate tracks, and sent the resulting data to other ships in a task force using pulse-code modulation radio signals.^[4]


DATAR's trackball used four disks to pick up motion, two each for the X and Y directions. Several additional rollers provided mechanical support. When the ball was rolled, the pickup discs spun and contacts on their outer rim made periodic contact with wires, producing pulses of output with each movement of the ball. By counting the pulses, the physical movement of the ball could be determined.


Since 1966, the American company Orbit Instrument Corporation produced a device named X-Y Ball Tracker, a trackball, which was embedded into radar flight control desks.^[5][6]


A similar trackball device at the German Bundesanstalt für Flugsicherung was constructed by a team around Rainer Mallebrein of Telefunken Konstanz as part of the development for the Telefunken computer infrastructure around the main frame TR 440, process computer TR 86 and video terminal SIG 100-86,^[7] which began in 1965.^[5] This trackball was called Rollkugel (German for "rolling ball"). Somewhat later, the idea of "reversing" this device led to the introduction of the first computer ball mouse (still named Rollkugel, model RKS 100-86), which was offered as an alternative input device to light pens and trackballs for Telefunken's computer systems since 1968.^[5][8][9]


In later trackball models the electrical contacts were replaced by an optical chopper wheel, which had small slots cut into it in rather than electrical contacts. With an LED for illumination from one side and an optical sensor on the other, rotation of the wheel periodically blocks and unblocks the light, so the sensor produces electrical pulses to indicate that rotation is occurring.


Mice used the same basic system for determining motion, but had the problem that the ball was in contact with the desk or mousepad. In order to provide smooth motion the balls were often covered with an anti-slip surface treatment, which was, by design, sticky. Rolling the mouse tended to pick up any dirt and drag it into the system where it would clog the chopper wheels, demanding cleanup. In contrast the trackball is in contact only with the user's hand, which tends to be cleaner. In the late 1990s both mice and trackballs began using direct optical tracking which follows dots on the ball, avoiding the need for anti-slip surface treatment.


As with modern mice, most trackballs now have an auxiliary device primarily intended for scrolling. Some have a scroll wheel like most mice, but the most common type is a “scroll ring” which is spun around the ball. Kensington's SlimBlade Trackball similarly tracks the ball itself in three dimensions for scrolling.


As of 1989 and into the 2020s, two major companies developed and produce consumer trackballs, Logitech and Kensington, although Logitech has narrowed its product line to two models. Other smaller companies occasionally offer a trackball in their product line. Microsoft produced popular models including The Microsoft Trackball Explorer, but has since discontinued all of its products.


In September 2017 Logitech announced release of MX-Ergo Mouse,^[10] which was released after 6 years of its last trackball mouse.