JPS6145286B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic head, in which a plurality of gaps having mutually different gap cross-sectional areas divide recording signals according to their frequency bands, and can perform recording with high fidelity. The purpose is to provide a magnetic head.

Conventional magnetic heads typically record audio signals on magnetic tape using a gap in one of the cores, but in this case, in order to improve recording frequency characteristics, especially high frequency band signal characteristics, The above gap width must be made small.

However, reducing the gap width causes difficulties in manufacturing technology and reduces reproduction sensitivity.
Even with the best technology available to date, there is almost no upper limit to the recording frequency characteristics in the case of low-speed recording where the relative speed of the magnetic head and magnetic tape is approximately 1 cm/sec.
It has a low frequency of 5 kHz, and has the disadvantage that it is impossible to record the upper limit frequency of about 10 kHz or more required for faithful reproduction of audio signals.

Therefore, the present invention provides a magnetic head having a normal gap width and capable of recording high frequency band signals well.One embodiment of the present invention will be described below with reference to the drawings.

FIGS. 1 and 2 are a plan view showing a schematic configuration of one embodiment of a magnetic head according to the present invention, and an enlarged partial plan view showing a state in which a tape is attached to a core gap portion thereof. In each figure, 1 is a magnetic head, and its core 2 is made by joining a pair of core halves 3 ₁ and 3 ₂ each made of a magnetic material such as ferrite or permalloy into a C-shape. A relatively large magnetic plate 4 made of ferrite or permalloy is inserted into the tip gap of the pair of first and second magnetic plates.
gaps 5 and 6 are formed. Furthermore, core half 3 ₁
In particular, a magnetic core portion 3a made of the same material as the core half ₃₁ and having the same shape as the magnetic plate 4 is integrally joined to the core half ₃₁ on the gap forming surface of the core half 31. Therefore, as shown in FIG. 2, the magnetic plate 4 connects the magnetic core portion 3a and the core halves 32 through the non-magnetic material 7, such as glass, filled in the first and second gaps 5, _6, respectively. The magnetic plate 4 faces and is spaced apart from the tip surface 3b, but the gap depth of the magnetic plate 4 is more than three times that of the tip surface 3b (the gap width dimension is approximately 0.5μ for each). The magnetic path cross section of the second gap 5 is more than three times that of the second gap 6.

8 is a coil, which is wound around the core half body 31 in FIG. ₁ and is connected to a circuit 10 described later.A coil terminal 8
It has a, 8b. Similarly, the coil 9 is connected to the core half 3.
₂ and has coil terminals 9a and 9b.

In the circuit 10 shown in FIG.
The audio signal supplied to 1 is subjected to desired signal processing in a recording signal processing circuit 12 that includes an AGC (automatic gain control) circuit amplifier, an equalizer circuit, etc., and is then processed by a low frequency waveform generator 13 and a real frequency waveform generator, respectively. 15. The low frequency band signal passed through the low frequency wave generator 13 and waved at a predetermined cutoff frequency is sent to the bias circuit 14.
A deep high-frequency bias current supplied from the coil 9 is superimposed and supplied to the coil 9 via the coil terminals 9a and 9b.

On the other hand, the high-frequency band signal generated by the high-frequency amplifier 15 at a predetermined cutoff frequency is amplified by the amplifier 21 and delayed for a predetermined time by the delay circuit 22. It is supplied to the coil 8 through the coil 8.

By energizing the coils 8 and 9, the magnetic flux is transferred to the core half 3 ₁ , the first gap 5, the magnetic plate 4, and the second
It passes through a magnetic path consisting of a gap 6 and a core half ₃₂ . At this time, the first and second gap 5,
The distribution and generation direction of the magnetic flux 24 at and near the magnetic flux 24 are as shown by the dotted line in FIG.

In FIG. 2, if we first focus on the magnetic flux caused by the high-frequency bias current from the bias circuit 14, its frequency is usually 50 to 200 kHz, and the magnetic flux density is sparse in the first gap 5, as shown in the figure.
In the second gap 6, it is relatively dense,
Although it is inversely proportional to the magnetic path cross-sectional area of the gaps 5 and 6, as mentioned above, since the gap cross-sectional area of the first gap 5 is three times or more that of the second gap 6, the magnetic flux density ratio is also three times or more. Therefore, as shown in the figure, the magnetic flux 24a generated in front of the first gap 5 by the high frequency bias current is relatively small and magnetizes the shallow portion of the magnetic layer 23a. The magnetic flux 24b generated at the front surface of the second gap 6 is relatively large and magnetizes the magnetic layer 23a to a deep portion. In this way, the recording signal is recorded with a deep bias by the second gap 6 based on the deep high frequency bias current,
Moreover, the first gap 5 records a shallow bias.

Next, focusing on the recording signal, in the first gap 5, the high frequency band signal supplied from the coil 8 without bias is recorded with a shallow bias as described above. The level of the high-frequency band signal supplied to the coil 8 is set to be higher than the level of the low-frequency band signal by the high-frequency bias method, which is amplified by the amplifier and supplied to the coil 9, to compensate for various losses during recording as known in the art. In particular, this is to compensate for the case where the magnetic flux for recording is small because the magnetic flux density of the first gap 5 is sparse as described above. Therefore, in the first gap 5, due to the shallow bias method in the first gap 5, good recording can be performed without producing the demagnetizing effect, which will be described later.

In the second gap 6, the low frequency band signal supplied by the coil 9 is recorded. In this case, the low frequency band signal superimposed on the deep high frequency bias current as described above enters the coil 9, but the level of the low frequency band signal is set in advance to be relatively low as described above. Therefore, the low frequency band signal is recorded in the second gap 6 where the magnetic flux density is high, but not in the first gap 5 where the magnetic flux density is low.

The reason why only the low frequency band signal is recorded in the second gap 6 and the high frequency band signal is not recorded is as follows.
When the recording signal is recorded using the normal deep high frequency bias method as in the case of the second gap 6,
This is because the high frequency band components of the recording signal are demagnetized, making it impossible to record. This is thought to be because the higher the signal frequency of the recording signal is, the more the surface portion of the magnetic layer 23a of the magnetic tape 23 is used, so the demagnetization effect becomes more effective. It is known that demagnetization largely depends on the magnitude of the bias current, and the larger the bias current, the greater the demagnetization.

Here, the high frequency band and low frequency band signals are transmitted to the magnetic tape 23 by a pair of gaps 5 and 6, respectively.
This will cause an inconvenience that a recording position error will occur between the two signals on the tape 23 that are simultaneously recorded on the tape, but in reality, if the thickness of the magnetic plate 4 is sufficiently thin, the delay time between the two gaps 5 and 6 will be the same. For example,
It has been confirmed that the time is 30msec or less and there is no problem in practical use. However, in this example,
The delay circuit 22 eliminates the above disadvantage.
That is, as shown in FIG.
After the low frequency band signal of the recording signal is recorded on the magnetic tape 23 with a deep bias, the high frequency band signal is instantaneously delayed by the delay circuit 22 by the first gap 5, and the recorded low frequency band signal is recorded with a shallow bias. are recorded overlappingly on the same track. Thus, the audio signal is first divided into a high frequency band and a low frequency band at a predetermined crossover frequency, and then the second gap 6 records the low frequency band signal with the normal deep bias, and the first gap 5 records the high frequency band signal. Band signals are recorded in shallow vias, and the disadvantage that the signal level of high frequency band signals is reduced due to the demagnetizing effect due to deep high bias currents is eliminated.

Note that when reproducing the signal recorded on the magnetic tape 23, a commonly used reproducing magnetic head composed of a single magnetic gap may be used, or the second gap 6 of the core 2 may be used. The reproduced signal may be extracted from the coil 9 using the following.

Further, in the above embodiment, a pair of gaps 5 and 6 are formed by one magnetic plate 4, but the present invention is not limited to this, and three or more gaps may be formed by two or more magnetic plates, and three or more gaps may be formed in the core. It is also possible to have a configuration in which more than one coil is wound.

As described above, according to the magnetic head of the present invention, a plurality of gaps are formed by interposing a magnetic plate in the tip gap of the core, and the cross-sectional area of each gap in the magnetic path forming direction is made different from each other to increase the magnetic flux density. They are different from each other and have a structure in which a plurality of coils are wound around the core, each corresponding to each gap, so that the high frequency bias current during signal recording produces a high density magnetic flux in the gap with a small cross-sectional area, resulting in a deep magnetic flux. In order to not only produce the effect of bias recording but also produce a low-density magnetic flux in a gap with a large cross-sectional area and produce the effect of shallow bias recording, for example, it is possible to divide the audio signal to be recorded and combine the low frequency band signals. The above-mentioned deep high bias recording is performed through the above-mentioned small cross-sectional area gap through the coil, and shallow bias recording is performed using the above-mentioned large cross-sectional area gap through the high-frequency band signal through another coil. There is no inconvenience such as signal level drop due to demagnetization effect during deep bias recording of signals.
For example, even when the relative speed between the magnetic head and the magnetic tape is small, high-frequency band signals can be recorded particularly well, and tape speeds can be reduced, long-time recording based on this, and high-fidelity recording possible. The width is the same as usual, and the structure is simple and easy to manufacture, as it only requires adding a magnetic plate to a normal magnetic head. Also, by simply adding a magnetic plate, it can be made into approximately one size of a normal magnetic head. It has the features of being extremely practical, having the functions of two units in just one unit.

[Brief explanation of the drawing]

1 and 2 are respectively a plan view showing a schematic configuration of one embodiment of the magnetic head according to the present invention and an enlarged partial plan view showing a state in which a tape is attached to the core gap portion thereof, and FIG. FIG. 3 is a block system diagram of connected external circuits. 1... Magnetic head, 2... Core, 3 ₁ , 3 ₂ ...
... Core half, 3a ... Magnetic core part, 4 ... Magnetic plate, 5, 6 ... Gap, 8, 9 ... Coil, 8
a, 8b, 9a, 9b...Coil terminal, 10...
External circuit, 12... Recording signal processing circuit, 13...
Low frequency device, 14...Bias circuit, 15...High frequency device, 21...Amplifier, 22...Delay circuit,
23...Magnetic tape.

Claims (1)

[Claims] 1 A plurality of gaps are formed by interposing a magnetic plate in the tip gap of the core, and the cross-sectional area of each gap in the direction of magnetic path formation is made to be different from each other, so that the magnetic flux density is made to be different from each other, and the core corresponds to each gap, respectively. A magnetic head characterized in that it has a structure in which a coil is wound around the magnetic head.