Patent ID: 7113872

Claim:
A metal surface inspection device for metal rings of a Continuously Variable Transmission (CVT) V-belt comprising: a light source for illuminating an inspectable surface of said metal rings to be inspected; a first light guiding path for guiding a reflected light from said inspectable surface to a first light detector and a second light guiding path for guiding said reflected light to a second light detector; a difference value calculation means for calculating a difference value between an electrical signal outputted from said first light detector or an electrical signal correlated to the electrical signal outputted from said first light detector and an electrical signal outputted from said second light detector or an electrical signal correlated to the electrical signal outputted from said second light detector; and a discrimination means for discriminating the existence of a defect on said inspectable surface and comparing said difference value with a predetermined threshold value, in which said metal surface inspection device is provided with an integral value calculation means for calculating an integral value of said difference value and difference value correction means for correcting the amount of said difference value based on said integral value; said difference value correction means corrects said difference value in a decreasing direction when said integral value increases exceeding a predetermined value; and said discrimination means discriminates the existence of a defect on said inspectable surface and compares said difference value corrected in said difference value correction means with a predetermined threshold value.