| 摘要 |
PURPOSE:To enable visual recognition of a target without using a transit, by installing light projector directing a beam of light to the planned direction of propulsion, target positioned in the machine proper, and optical fiber transmitting, to the outside of the machine proper an image of the target on which the beam is thrown. CONSTITUTION:A beam of light 1 emitted from a light projector 2 is oriented always to the planned direction of propulsion. And, the rear side of a target 4 is connected to an optical fiber 5 and the optical fiber 5 is led out of the hole and the beam of light 1 projected onto the target 4 is recognized as an image on a screen. When the shielding machine A is propelling horizontally, the beam 1 strikes right the center of the target 7. Next, when the machine A tilts upward or down ward with respect to the direction of propulsion, it is deviated from the center of the target 4. |
