| 摘要 |
PURPOSE:To implement the high speed checking processing by comparing the minimum value of the interval between the pulses of a binary coded signal of a sensor output based on the reflected light from the surface to be checked with a specified threshold value. CONSTITUTION:The reflected light from the rotating surface to be checked having seamed parts is detected by a fiber sensor 601. The output thereof is guided to polarity discriminating circuits 606-608 through BPFs 603-605 having different cut off frequencies, and only one polarity is extracted. The signals are compared with a specified DC level in comparators 609-611, coded to the binary signals, and inputted to preprocessing circuits 612-614. Parts of the signals are directly inputted to a pulse interval measuring circuit 616, the other parts are inputted to the circuit 616 through an OR circuit 615, and the pulse interval is obtained. The signal from the circuit 616 is inputted to a minimum value detecting circuit 617, and the minimum value of the pulse interval is compared with the threshold value in a judging circuit 618. If the signal is small, it is determined that the product is defective. Thus the high speed checking process can be implemented by the inexpensive means. |
