Fault detector for information storage discs - detects faults due to scratches on spiral track of rotating disc, by using shift registers and logic gates

摘要

The fault detector compares the faulty signal obtained during one complete revolution of the disc with the signal obtained during the preceeding revolution. If the fault repeats itself in the next revolution (or the next two, three etc. revolutions) then a multiple-fault is registered (i.e. a scratch). The disc signal is applied to a first shift register (SR1) whose length is equal to one revolution. The register's inverting output is combined via an AND-gate with the input to produce a fault signal indicating a single fault. A second AND-gate combines input and output to produce a second fault signal indicating several faults.