SU1078464A1 - Process for measuring penetration in combined head stack - Google Patents

Abstract

A METHOD FOR MEASURING THE PENETRATION IN A COMBINED LOCK OF MAGNETIC HEADS by periodically supplying signals of various frequencies to the recording head and measuring the amplitude of the penetration voltage in a reproducing head, characterized in that, in order to reduce the measurement error, the recording head simultaneously records the cuttings, which are recorded by the recording heads simultaneously recording the cuttings, which are recorded in that the recording head simultaneously records the cuttings, which make it possible for the recording head to simultaneously record cuts, which are used in order to reduce the measurement error, the recording head simultaneously records the cuttings, which are recorded by the recording heads at the same time. working frequencies, setting the length of these segments to be equal to the distance between the AIRPLANES and the working gaps of the recording and playback heads, the recorded segments of the waveforms of the playback The amplitudes of the penetration signals in the reproduction head are recorded, measured in intervals of action in the recording head of the recording and biasing currents, and the electromotive reproduction force of the recorded signals in the absence of recording intervals, after which the ratio of the amplitudes of the penetration signals to electr-S is determined. to the strength of the reproduced W signals, at this distance between the end of the previous one and the beginning of the subsequent segments, the distance between the working gaps of the recording heads and the reproduction and. 4j 00 4 O) 4

Description

The invention relates to instrumentation, in particular, to a method by which it is possible to determine the magnitude of the penetration voltage occurring in a combination unit of magnetic heads used mainly in tape recorders, i.e. where, under structural conditions, it is not possible to disassemble the recording and playback heads along the magnetic tape movement. Virtually any distance between the magnetic recording and playback heads in the up-to-date an. Parature is the mutual influence of the fields of these heads. Moreover, such floors begin to show up in combined structures, i.e. when the recording and playback heads are com paned in a common case and with a minimum distance between their magnetic conductors. If single measurements are made by recording labels along the direction of movement of the magnetic tape l, and then they are extracted from reproducing frequency signals from the frequency components, then it becomes necessary to compare the signals by peak detection. It is quite clear that such a process is long and suitable mainly for research work, but not for mass production of head blocks. In this case, the method of creating a step voltage {2j is more convenient, which allows to expand the spectrum of analyzed frequencies. But with all its positive qualities, this method can only be used in expensive equipment, since the measurement process itself is not cheap. Attempts to simplify such a method by reducing the number of operations associated with the use of an electric circuit of a meter leads to a complication of the mechanical part, which requires the use of highly qualified operators from the closest to the proposed method of measuring penetration in a combined block of magnetic heads, . based on the periodic supply of signals of different frequencies to the recording head, followed by measuring the amplitude of the penetration voltage in the reproducing head 4. However, such a method, although it is pro and inexpensive, leads to relatively large measurement errors. The purpose of the invention is to reduce the measurement error. This goal is achieved by using the method of measuring, penetrating magnetic heads in the combined section by periodically feeding signals of different frequencies into the recording head and measuring the amplitude of the penetration voltage in the reproducing head, recording heads simultaneously record the signalograms (signalograms) of the reference and the highest working frequency, set the length of the airs of the segments equal to the distance between the working gaps of the recording and playback heads, the recorded segments of the soundtrack are produced, measured at intervals in the recording head of recording and biasing amplitudes of the penetration signals in the playback head, and in the absence of recording currents - the electromotive reproduction force of the recorded signals, then the ratio of the amplitudes of the penetration signals to the electromotive force of the reproduced signals is determined , while the distance between the end of the previous one and the beginning of the next segments is chosen to be less than the distance between the working gaps of the recording heads and the Bqc process. FIG. 1 shows a block diagram of a device-a for carrying out the method; FIG. 2 conventionally shown is a magnetic tape with an developed waveform; in fig. 3 and 4 waveforms in separate units of the device. When implementing the method, the device uses a reference frequency generator 1, a higher frequency generator 2 of the operating range, and a frequency generator 3 of the bias current. All three generators are connected through a mixer 4 and switch 5 to a test block of magnetic heads 6, which includes a recording head 7 and a playback head 8 interacting with a magnetic tape 9. The playback head is connected directly to three filters: to a filter 10 of the highest operating frequency range, the reference frequency filter 11 and the bias current frequency filter 12. All filters are connected to a dual-beam oscilloscope 13, while filter 10 is connected to the oscilloscope via input 14 / and filters 11 and 12 through input 15 of the same oscilloscope. Position 16 shows segments: waveforms, and position 17 shows the distance to the meiod of the end of the previous one and the beginning of the next segments of the waveform. A feature of the proposed method is to conduct measurement operations using two stages of operation: the first is the recording stage in which both heads of the block operate, the second is the playback-only stage in which the

ONLY the playback head. During the implementation of the first stage, the tape recordings 16 are recorded on magnetic tapes, where the length of the cassette is equal to the distance between the working gaps 18 and 19, respectively, of the recording and playback heads. In this case, the recording of signals is carried out from all three generators. Distance 17, i.e. the section that does not have a record is shorter in length than the distance 16. Thus, in the first stage, the section having a distance of 17 (which does not have a record) passes by the reproduction head first, which makes it possible to have an idea of the penetration value, and then 16 (but maybe the other way around - the moment is not significant). At the second stage, the bias current does not exist, i.e. there is no interference from the recording head. As a result, at the input 14 there takes place the alternating presence of penetration voltage (Fig. 3) and the signal reproduced from the tape with the upper frequency of the working range, which creates amplitudes A and Al. The ratio of these amplitudes can be judged on the magnitude of the signal penetration from the head 7 into the head 8 at the highest frequency of the operating range, lio the axes of ordinates in FIGS. 3 and 4 are the voltages at the inputs 14 and 15, respectively. The abscissa axis in FIG. 3, the frequencies of the working range are plotted, i.e. higher frequencies of this range. FIG. 4 on the x-axis

0 the reference frequencies are plotted (, Aj is the amplitude in the recording mode of the magnitude of the magnetization, A4 is the amplitude of the reference frequency signal). In relation to the amplitudes A and A4, the value of

5 level of bias current penetration from recording head 7 into reproduction head 8.

The proposed method, in addition to increasing the efficiency of measurements, allows to increase the quality of control of the combined blocks of heads. As a result of its implementation, it is possible not only to reduce the scrap in the process of manufacturing the magnetic recording equipment as a whole, but also to reduce operating costs.

Ш1111Н1ШН1Ш11 ||| {{}} | ЦЦ |

u, {t}

FIG. 2

%BUT;

Claims (1)

METHOD FOR MEASUREMENT OF PERMISSION IN A COMBINED MAGNETIC HEAD UNIT by periodically supplying Signals of various frequencies to the recording head and measuring the amplitude: penetration voltage in the reproducing head, which differs in that, in order to reduce the measurement error, the recording head simultaneously records segments of the signalograms of the reference and higher working frequencies, setting the length of these segments equal to the distance between the working gaps of the recording and playback heads, the recorded segments of the signalograms reproduce, in the intervals of action in the recording head of recording currents and magnetization of the amplitude of the penetration signals in the playback head, and in the intervals of absence of recording currents the electromotive force of the reproduction recorded in the signal segments, after which the ratio of the amplitudes of the penetration signals to the electromotive force of the reproduced signals is determined, the distance between the end of the previous and the beginning of the subsequent segments choose less than the distance between the working gaps of the recording and playback heads. φη-f _n? SU .. „1078464