DETECTION OF STAIN FLAW IN MAGNETIC DISK AND INSPECTION DEVICE

摘要

PURPOSE: To detect stain itself by detecting a change in the hue of the stain to a medium. ;CONSTITUTION: White light is projected to the medium and the reflected light is dissociated by three primary color filters and received by a photodetector 49 which outputs the chrominance signal currents IR, IB, IG corresponding to R, G, B respectively. The currents IR, IB, IG are inputted to dividers 52a, 52b which output chrominance signal ratios IR/G, IG/IB and apply these ratios to the positive and negative terminals of comparators 53a, 53b, 53c, 53d. On the other hand, the respective chrominance signal currents are added to an adder 54. A white signal current IW which is the output thereof is added to a threshold voltage setting circuit 55. The adequate threshold voltage by the stain is previously found and inputted to the circuit 55 which outputs and sets the threshold voltages S₁ and S₂ by referring to the current IW to the respective comparators. The changes in the chrominance signal rations IR/G, IG/IB inputted to the respective comparators are detected and outputted to a stain detection signal to be displayed on a display device 63. Consequently, the stain flaw of the medium surface is detected.;COPYRIGHT: (C)1993,JPO&Japio