Tribo-electric Energy

• Hawk-Eye Sensors use Tribo-Electric Energy charges to determine when a tennis ball strikes a sensor placed on or near the boundary lines of the tennis court. Tribo-electric energy is the static charge resulting when two objects rub against each other. In Hawk-Eye’s case, the insulation on our wire rubs against the insulation on the inner side of the laminate which is sealed onto the wire.
  	The use of Tribo electric energy for commercial purposes was first patented in 1957 as the basis for detecting boundaries. Its initial uses were to define boundary lines that would help with alarm systems for houses or commercial properties. In 1997 its use was incorporated into tennis boundary lines. It is seen as the most accurate and economical way to determine boundaries.
  	Although very small voltages are generated when the tennis ball hits the sensor line, the use of proprietary logic circuits (amplifiers and filters) enables the pattern of voltage releases to be observed. As illustrated to the left, the pattern emitted when a tennis ball hits the sensors is very clear and discernible. A foot hitting or scraping across a tennis line results in a very different pattern.
  	Tribo-electric Sensors are extremely accurate and will register being hit by a tennis ball, but will not register any voltage when the ball misses the sensor by hundredths of an inch. The picture to the left illustrates a ball dropped next to the line, but just missing.