Electrical methods are considered the best for detection of a weft incompletely inserted on the selvage opposite the nozzle of a water jet loom. With this in mind, research has been made and a detector developed. The research included efforts to find out the conditions that a detecting part and a detecting circuit must satisfy and to obtain data on developing a serviceable detector.
Results: 1) The electric resistance of wet yarns is less than several hundred M Ω, except in some special yarns.
2) The electrical insulation of the detecting part (which holds the electric feeler fingers) has to be as high as possible. The pulse wave generated from the feeling fingers by water-jetting is partially similar to the pulse generated by the contact of a weft.
3) A detecting circuit consisting of a computor circuit works fairly well, with very few wrong actions.
4) In an actual running test, a few wrong-actions developed. This needs looking into. Mean while, the detector we have developed is serviceable.