JPS573277A - Displaying method for magnetic tape running time - Google Patents

Abstract

PURPOSE:To display a magnetic tape running time with high precision through simple constitution, by retrieving the time data corresponding to circumferential length on the basis of variations in rotation detection pulse intervals of a feed and take-up reel spindle. CONSTITUTION:Each time pulses whose intervals of generation increase according to an increase in take-up diameter detected by a take-up reel spindle detecting circuit 1 are counted by the reference counter 3b of a take-up diameter counting circuit 3 by a prescribed number such as four, detection pulses for feed reel spindle rotation counted by a diameter measuring counter 3a are latched by a latch circuit 3c. On the basis of the latch contents which correspond to the take-up tape diameter, a tape running time is retrieved in a time data circuit 4 corresponding to circumferential length consisting of an encoder 4a, etc., and then applied to an accumulated-second pulse converting circuit 5 provided with a switching circuit 5b which corresponds to a tape running direction, a signal pulse converting circuit 5a which generates a one-second pulse by counting feed-reel rotation detection pulses, etc. Therefore, the running time is displayed with high precision through the simple constitution in both fast-forwarding and rewinding modes without reference to an initial running position.