Patent ID: 7466431

Claim:
A method of measuring a length of a band-shaped member comprising steps of: moving two-dimensional laser displacement sensors emitting laser beams inclined at a certain angle with respect to a longitudinal direction of the band shaped member and the band-shaped member relative to each other in the longitudinal direction of the band-shaped member, detecting repeatedly each position of a starting end and a terminating end of the band-shaped member crossing the laser beams by said two-dimensional laser displacement sensors each time a relative moving distance between the two-dimensional laser displacement sensors and the band-shaped member reaches a certain value, and obtaining a position information of the starting end and the terminating end of the band-shaped member at each width-direction position from a detection result thereof; and obtaining the length of the band-shaped member at each width-direction position based on the position information of the starting end and the terminating end at each width-direction position.