US Patent 7393098 Liquid jet writing instrument

A writing instrument comprising a liquid spray head and a processor unit serving to activate the spray head. The instrument further comprises measurement means for measuring the distance between the spray head and the medium, and movement detector means, the processor unit being adapted to activate the liquid spray head when at least the measurement means determine that the distance between the spray head and the medium is less than a predetermined maximum value, the processor unit also being adapted to manage activation of the spray head as a function of the movement detected by the movement detector means.