SU131953A1 - Apparatus for checking the quality of magnetic tape coating and detecting defects in them - Google Patents

Description

Devices are known for checking the quality of the magnetic coating of the tape and the detection of defects in them.

The device is based on recording of alternating currents of a CONSTANT amplitude on a magnetic carrier and contains a flow control mechanism for rewinding the tested tape, as well as a recording and reproducing heads. However, the known devices do not provide the possibility of automatically counting the number of defective places of different lengths along the length of the tape.

In order to ensure automatic counting of the number of defective places in the device, they are applied; a) an allocation circuit designed to convert the signals of the reproducing head into square pulses, the duration of each of which corresponds to the length of the defective place along the length of the tape; b) a series of KIPP relays creating electrical impulses of various duration at the outputs; c) coincidence circuits designed to compare the pulse durations of each of the KIPP relays with the output pulses of the extraction circuit, the output signals of which serve after their respective conversion to activate a series of counters, each of which counts the number of defects of one or another place on checked tape.

FIG. 1 shows a block diagram of the proposed device; in fig. 2 is a block diagram for the selection of output oscillations based on the depth of the dip and its duration;

As a tape mechanism, any tape mechanism can be used. Record amplifiers 7 and playback 2 are also used from typical magnetic recorders. The magnet carrier is squeaked with a signal from a sound generator.

№ 131953- 2. By knowing the speed of the tape pulling and the duration of the dip in the reproduction, it is possible to determine the geometrical size of the defect in the direction of the sweep. By knowing the depth of the parasitic amplitude modulation, it is possible to determine the geometric size of the defect in the direction perpendicular to the sweep. However, for practical use, the data on the duration of dips in the reproduction of signals of a constant level and on the depth of spurious amplitude modulation are significant.

The signal from the output of the playback player is fed to the input of the allocation circuit 3, which, in case of a dip in the reproduced signal, will generate a pulse whose duration is equal to the duration of the dip, and this pulse will be generated only if the depth of the dip is greater than the amplitude limit of the selector as part of an allocation scheme.

Thus, selection is made according to the depth of the dip.

The leading edge of this pulse is triggered by KPi, KPz, Khaz, KP and KPs relay relays that determine the duration of dips in playback selected in this channel after a time delay in the URF pulses from these kipp-relays fall on the difference schemes 4, where they are compared in duration with the pulse formed by the formation scheme 3. In those channels where the specified duration of the Kipp-relay is longer than the duration of the dip, the output of the mismatch circuit in TC is pulses that after differentiation and phase reversal in the phase inverter blocks FIs start a Kipp relay. facing the decoder 5.

Thus, depending on the duration of the failure, some KIPP relays 6 will be triggered. Signals from them are sent to a decoder, which decodes the resulting combination and starts the KMP KIPP-relay 7 of that channel, in the range of which the failure fell. The load of this KIPP-relay is the counter 8. Thus, the selection is made according to the duration.

If the duration of the failure exceeds the maximum KIPP-relay, then the counter of long failures is triggered 9.

The device can operate in two modes: account and search.

When working on account, the classification and counting of defects occurs, and during operation in the search mode, the tape drive mechanism stops at the moment of occurrence of a defect, due to which a defective place of the magnetic carrier can be detected and investigated. For this purpose, a block stopping mechanism 10 is used.

Subject invention

A device for checking the quality of magnetic tape coatings and the detection of defects in them, based on recording variable currents of constant amplitude on a tape and containing a tape mechanism for rewinding the tape being tested, as well as recording and reproducing heads, characterized in that For the purpose of automatically counting the number of defective places of different lengths along the length of the tape, the device jointly applied: a.) an allocation circuit designed to convert the signals of the reproducing head into straight lines char pulses, the duration of each of which corresponds to the length of the defective place (dip) along the length of the tape; b) a series of Kipp-relays with delay circuits of various duration, launched simultaneously

a pulse of the extraction circuit and outputting electric pulses of various durations, and c) a coincidence circuit designed to compare the pulse duration of each of the kiprele with the output pulse of the extraction circuit, the output signals of which serve after their respective conversion. to accommodate a number of counters, each of which counts the number of defective places of a certain length on the tape being tested.

FC

F