PLATE EDGE POSITION DETECTING DEVICE, METHOD FOR MEASURING PLATE WIDTH, AND METHOD FOR MEASURING MEANDERING AMOUNT OF PLATE

PROBLEM TO BE SOLVED: To provide a plate edge position detecting device, a method for measuring plate width, and a method for measuring meandering amount of plate wherein, with measurement error as small as possible, the edge position, width, and meandering amount of a plate can be accurately measured. SOLUTION: At least three measurement cameras A, B, and C, are provided above both edge parts 11 of a plate 10, two are selected among the measurement cameras A, B, C corresponding to a plate width W and lateral deflection amount Y of the plate 10, and base on the measurement signal of the two measurement cameras, an edge position PD is calculated using an intersection-point method which requires no plate-thickness information. Thus, the detection precision for the plate edge position is significantly raised.