MEASURING DEVICE FOR SCREW ELEMENT

PURPOSE:To improve resolution and to enable to perform a high-precise measurement of a screw element, by using an optical system which limits a visual field of a two-dimentional photographing device. CONSTITUTION:A steel pipe 10, which has a screwed outer periphery, is located in a horizontal manner, light is radiated from one side by an illuminating lamp 27, and a two-dimentional photographing device 11, such as a television camera, is situated at the other side. Through location of mirrors 21-24 between the television camera 11 and the steel pipe 10, the photographing visual field of the television camera 11 is limited to upper and lower outer edge parts 10a and 10b (a part including screw thread) of the steel pipe 10. A picture photographed by the camera 11 produces a picture signal by means of a television camera controller 12, it is displaced by a monitor 13, and simultaneously, it is inputted to a picture processor 14. Position data of a bright and dark boundary part for showing a screw shape can be obtained in the processor 14. A computing device 15 prints and records computing results of the screw element by means of a printer 16, and meanwhile, in case computing results of each element is out of an allowable tolerance, an alarming device 17 is actuated.