Central line determinator

The utility model discloses a central line determinator, which belongs to a coal mine underground work device, which comprises a lens cone, wherein the left end of the lens cone is fixed with a convex lens I and a horn nozzle, the right end of the lens cone is provided with a mobile convex lens device, and the side wall of the lens cone is provided with two fixing rings. The using process of the central line determinator is that the central line determinator is respectively bolted on two iron rings of a central line measuring instrument steel cylinder according to wire ropes which flap down from two original central line points of a roadway, thereby leading the iron rings to keep static, and then the distance between the convex lens I and a convex lens II is adjusted until turning up a detected central line point before the roadway according to the light-gathering characteristics of the convex lens through putting a mine lamp on a horn port of the central line detector. Compared with the prior art, the centra