Malfunction detection device null of impulse

摘要

PURPOSE: To detect an abnormal state automatically by comparing an electrical signal with a first threshold for obtaining the corresponding first electrical signal output, comparing it with a second threshold which is lower than the first electrical signal output for obtaining the corresponding second threshold, comparing the corresponding first electrical signal output with the corresponding second threshold for obtaining a difference in reference to the corresponding second electrical signal, and then judging whether the difference is within a specified allowable range or not. ;CONSTITUTION: A contact-type encoder is provided with a first comparison means with a comparator 5 which compares an electrical signal of a detection part 4 with a first threshold and a first counter 6 which counts the number of electrical signals exceeding the threshold and then outputs a first count value, a comparator 7 which makes comparison with a second threshold which is smaller than the first threshold of electrical signal, a second comparison means which consists of a second counter 8, and a self-diagnosis CPU 9, thus enabling to judge whether the difference between the first and second count values is within a specified allowable range or not, an error signal is output when the range is exceeded, and then an abnormality signal is output when the count exceeds a specified count by integrating the number of error signal outputs.;COPYRIGHT: (C)1993,JPO&Japio