DETECTOR FOR PROJECTION ON SURFACE OF TUBE BODY

• Main Authors: OKAWACHI KOJI, IWASAKI MITSUO, FUJIKAWA HIROKI
• Format: Patent
• Language: English
• Published: 15.12.1988
• Subjects: MEASURING; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS; MEASURING LENGTH, THICKNESS OR SIMILAR LINEARDIMENSIONS; PHYSICS; TESTING

PURPOSE:To eliminate the need to change the position of a detector owing to variation in the external diameter of a pipe, to simplify the device of a signal processing part, and to perform stable detection by detecting laser light by transmission, rotating a tube body to be inspected at a constant speed, and extracting a local variation component of photodetection width. CONSTITUTION:A semiconductor laser 3 project the laser light on a tube axial line as the object 1 of inspection vertically or slantingly while making a vertical scan on it. This laser light is detected on a transmission basis by a photodetection part head 23. Then the object tube body 1 is rotated 3 and its rotational position is detected 4. Further, variation in the photodetection width detected as the object is rotated is detected 15. Then only its local variation component is extracted 17 and the variation rate of the variation component is extracted 18. Further, a level decision device 19 and a width decision device 20 detect a variation place and a variation rate place which exceed a constant level and constant width respectively. Then, the positions and heights of the variation place and variation rate place exceeding the constant level and constant width are detected 21.