Patent ID: 6989548

Claim:
An 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 its electrical signal and an electrical signal outputted from said second light detector or an electrical signal correlated to its electrical signal; and a discrimination means for comparing said difference value with a predetermined threshold value and discriminating the existence of a defect on said inspectable surface; said difference value calculation means includes: a first low-pass cutting means for cutting out a predetermined low-frequency component contained in an electrical signal outputted from said first light detector or an electrical signal correlated to its electrical signal and a second low-pass cutting means for cutting out a predetermined low-frequency component contained in an electrical signal outputted from said second light detector or an electrical signal correlated to its electrical signal; and said difference value calculation means calculates said difference value between an electrical signal which passes through said first low-pass cutting means and an electrical signal which passes through said second low-pass cutting means.