Testing moving, opaque material paths for the presence of holes - detecting light passing through material from transmitting to reception diodes

摘要

The material path (1) is illuminated and the light passing through the holes is detected on the opposite side of the material using photoelectric equipment which passes pulses to an evaluation device. The material is illuminated on one side by one or more rows of transmission diodes (3) which transmit parallel light which is deflected onto the material. At least one row of receiver diodes (4) is arranged on the opposite side of the material from the transmission diodes. Where there is a hole in the material, the corresp. diode receives light and feeds an electrical pulse to the evaluation unit. The transmission diodes can be individually sequentially stimulated to transmit light. USE/ADVANTAGE - E.g. for checking fine plate for presence of holes. Enables detection of holes in range 10 to 15 microns up to 5 mm. dia. at test speed of greater than 1000 m/min.; is insensitive to stray light.