| 摘要 |
PURPOSE:To highly accurately detect the distance between the tip of a nozzle and a work and to always keep the distance fixed by providing a 3rd electrode through an insulating member so that the external periphery of a 2nd electrode is enclosed and keeping the 3rd electrode in the same potential with the work. CONSTITUTION:The variation of an electrostatic capacity between the tip of the 1st electrode 12 and the work is detected by an electrostatic capacity detector 18 and a control circuit 19 controls the reciprocating motion of a nozzle drive gear 20 according to the voltage based on this variation to control the nozzle vertically. As a result, the distance between the tip of the nozzle 11 and the work W is kept fixed. In this case, the 2nd electrode 13 is kept in the same phase and on the same level with the 1st electrode 12 and the electrostatic capacity C can be detected decidedly between the tip of the nozzle and the surface of the work W vertical to electric lines of force from the 1st electrode 12. On one hand, since the 3rd electrode 14 is kept in the same potential with the work, the electric lines of force from the sides of the 1st electrode 12 and the 2nd electrode 13 to the work W can be shut off entirely. Consequently, the electrostatic capacity C between the 1st electrode 12 and the work can be detected surely. |
