| 摘要 |
<p>PURPOSE: To improve the reliability with a simple structure never inductively making contact with a drill string by connecting two output terminals constituting a transducer to the drill string and a conductive collar mounted thereon. CONSTITUTION: One output terminal 28 constituting the rotating transducer 26 of a transmitting device 24 provided on a boring tool 12 is directly connected to a drill string 14, and the other output terminal 30 is connected to a conductive collar 32 mounted on the drill string 14 through an inductive layer 34 and grounded. The AC signal from the transducer 26 is transmitted from the terminal 28 to a processing circuit 38 through the continued part of the drill string 14 and an annular transformer 36, and the ground surrounding a hole 18 and a tool 12 through an excavating fluid 22 and the terminal 30 are used as a signal return path. A conductive separator or a conductive roller energized to the side wall of the hole 18 may be used.</p> |
