JPS63244304A - Magnetic head - Google Patents

Abstract

PURPOSE:To suppress the noise from a inductive noise source or a crosstalk from the head of a reverse side or the like by arranging a first coil and a second coil, which generate alternately the recording magnetic fluxes of directions different from each other, independently of each other. CONSTITUTION:A reading/reproducing coil 15 is constituted of the first coil 17 which is wound around one half of a bobbin 16, and the second coil 19 which is wound around the other half of the bobbin 16 as being separated by the partition 18 at the nearly middle part of the bobbin 16 and it is packaged in a recording/reproducing core 4. Here, the first coil 17 and the second coil 19 are arranged as being divided by the partition 18, but the respective coils 17, 19 can be wound around the same two bobbins and can be packaged in the recording/reproducing core 4 as being superimposed in series. Thus, the combined capacity of the recording/reproducing oil of the magnetic head can be made small and even if it resonates by receiving the inductive noise from the head of the reverse side of the two sided FDD or from an outside, it does not record/reproduce for media, and the head which is strong against the inductive noise and does not generate the cross talk can be obtained.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a magnetic head such as a floppy disk drive (hereinafter referred to as FDD), and is particularly suitable for high-density recording/reproduction. This is to reduce the occurrence of errors.

[Summary of the Invention] The present invention provides a magnetic head such as an FDD that includes two coils and performs recording/reproduction by generating recording magnetic flux in different directions, in which the two coils are arranged independently from each other, By reducing the coupling capacitance m of these coils and increasing the resonance frequency determined by the coupling capacitance and coil inductance, suppressing noise from inductive noise sources and crosstalk from the head on the opposite side, etc., it is possible to prevent erroneous recording. This reduces the occurrence of errors such as erroneous playback.

[Prior Art] FIG. 5 is an equivalent circuit diagram of a magnetic head and a recording system conventionally used in an FDD. This magnetic head 1 is composed of a recording/reproducing head 2 and an erasing head 3. The recording/playback core 4 of the recording/playback head 2 records/
A reproducing coil 5 is wound around the recording/reproducing coil 5, and the recording/reproducing coil 5 is divided into a first coil 7 and a second coil 8 by a center tap 6. The number of turns of the first coil 7 and the number of turns of the second coil 8 are equal to each other, for example, 1
It is 60 turns. An erasing core 10 is arranged adjacently to the rear of the recording/reproducing core 4 (rearward in the disk movement direction indicated by the arrow &) with a spacer 9 interposed therebetween, and an erasing coil 11 is wound around the erasing core 10. ing. A pair of erase gaps I2 formed in the erase core 10
recording/reproducing gap 1 formed in the recording/reproducing core 4
It is configured to be located on both rear sides of 3.

In this magnetic head 1, during recording, a switch circuit 1 is connected from the center tap 6 to the first coil 7 and the second coil 8.
4, a recording current is caused to flow alternately, and recording magnetic fluxes A and B in mutually different directions are alternately generated in the recording/reproducing core 4 by the magnetomotive force of both coils 7 and 8. Then, a recording magnetized recording track is formed on the disk at the recording/reproducing gap 13 portion. At the same time as this record,
A DC erasing current is passed through the erasing coil 11, and the magnetomotive force of the erasing coil +1 generates an erasing magnetic flux E in a certain direction in the erasing core IO, erasing both sides of the recording track in the erasing gap 12 portion and securing a guard band. is configured to do so.

The coil 7.8 mentioned above is generally formed with bifilar winding as shown in FIG. This bifilar winding is
It is a winding method in which two conductive wires are wound as a pair, and the first coil 7 and the second coil 8 can be considered to be completely equivalent except for the difference in polarity. Therefore, the magnetic field generated at the recording/reproducing gap 13 during recording (writing) becomes symmetrical for each polarity,
Peak shift (displacement of recording position) that occurs in asymmetric cases
is prevented.

[Problems to be Solved by the Invention] However, in the recording system of the conventional recording head described above, since the coupling capacitance C of the coil 7.8 exists as shown in FIG. Since a resonant circuit is formed by C, there is a problem that the resonant frequency is easily induced in the presence of an inductive noise source. The coupling capacitance C is relatively large because the coil 7.8 is bifilar wound, and on the other hand, the resonant frequency f in the above-mentioned resonant circuit. is coil 7.8
If the inductance of is L, then fO=1/2π, rττ−, which becomes lower when the coupling capacity ff1C is large. Recent high-density media and heads have become capable of recording/reproducing at higher frequencies, and record/reproduce signals that are about 3 to 5 times the maximum recording frequency. The above resonance frequency f0 is 3 to 3 of the maximum recording frequency (f,,,,)
If it is about 5 times, the inductive noise of the resonant frequency f0 will be recorded on the medium, which will deteriorate the S/N of the already recorded recording surface and cause errors during reproduction.

Particularly in double-sided recording FDDs, the magnetic heads on both sides of the floppy disk are arranged to face each other, and even when writing on one side, the magnetic head on the other side is moved together with the magnetic head on one side to face each other. Therefore, the magnetic head on the write side becomes an inductive noise source for the magnetic head on the rest side. As described above, the recording current is alternately switched, resulting in a substantially rectangular wave, and therefore has large odd harmonic components. For this reason, if the magnetic head resonates with a harmonic component of 3 to 5 times the maximum recording frequency f + ma, it causes an error as described above. Note that the above is called crosstalk.

The present invention was made in order to solve the above problems, and reduces the coupling capacitance of the recording/reproducing coil of a magnetic head to reduce inductive noise from the outside or from the head on the opposite side of a double-sided FDD. The purpose of the present invention is to obtain a head that does not record/reproduce on/from media even if it resonates, is resistant to inductive noise, and does not cause crosstalk.

[Means for Solving the Problems] The configuration of the magnetic head of the present invention for achieving the objective is to include a first coil and a second coil and alternately generate recording magnetic flux in different directions. The magnetic head is characterized in that the first coil and the second coil are arranged independently of each other.

[Function] In general, the capacitance between two conductors is inversely proportional to the distance between the conductors, so the present invention separates the two coils and independently calculates the coupling capacitance, instead of closely contacting them as in the conventional bifilar winding. Make it smaller. This invention enables the magnetic head to record/record the resonance frequency of the magnetic head's resonant circuit formed by the coupling capacitance and the inductance of the coil by reducing the coupling capacitance.
Raise it outside the renewable area. Therefore, external inductive noise and crosstalk from the magnetic head on the opposite side of a double-sided FDD will not resonate in the recordable frequency range and be recorded on or reproduced from the media.

[Example] Hereinafter, an example of the present invention will be described in detail based on the drawings. The following embodiment shows a case where the recording/reproducing head is provided with two coils as in the conventional example, and recording magnetic fluxes in different directions are generated alternately by switching. Therefore, the same parts as in the conventional magnetic head will be given the same reference numerals and their explanation will be omitted.

FIG. 1 is a block diagram showing a first embodiment of the present invention. The recording/reproducing coil 15 in this embodiment includes a first coil 17 wound around one half of the bobbin 16, and a first coil 17 wound around the other half of the bobbin 16 with a partition 18 in the approximate center of the bobbin 16 in between. The recording/reproducing core 4 is constructed of two coils I9 and is inserted through the recording/reproducing core 4.

In the above example, the first coil 17 and the second coil 19 are separated by the partition I8, but each coil 17 and 19 is wound around two bobbins of the same shape, stacked in series, and passed through the recording/reproducing core 4. You can also wear it. Note that the partition 18 may be omitted, and by adjusting its thickness, the coupling capacitance between the two coils 17 and 19 can be made smaller within a desired range. Furthermore, when winding on two bobbins, the coupling capacity can be similarly made smaller and kept within a desired range by adjusting the distance of the gap between the bobbins. According to a fabrication example, the coupling capacity of the conventional 5opi';' can be reduced to about 10 pP.

In this embodiment, the first coil 17 and the second coil 19
If the number of turns is the same, it can be considered that they are almost equivalent, so the asymmetry of the generated magnetic field during recording (writing) in the recording/reproducing gap I3 can be minimized.

Another aspect of this embodiment is that the number of turns of the first coil 17 is larger than the number of turns of the second coil 19. The reason for doing this is that in the magnetic head of a high-density FDD, the recording/reproducing head 2 and the erasing head 3 are close to each other, and while the recording/reproducing head 2 is recording, trim-erase is performed on both sides of the recording track. This is to cancel the interference of the erasing (generally DC erasing) magnetic flux caused by the erasing head 3 when a certain gap (guard band) is generated. Figures 2 (a), (b), and (c) are explanatory diagrams of the interference of erased magnetic flux. In (a), if the first coil and the second coil are equivalent, the generated magnetic flux A of the first coil and the magnetic flux B generated by the second coil are equal. However, if there is interference from the leakage magnetic flux E' of the erasing magnetic flux E, the recording magnetization on the medium becomes asymmetrical as shown in (b), and (c)
As shown in the figure, a peak shift occurs during playback (the position indicated by the dotted line is the normal peak point). Therefore, as mentioned above, by increasing the number of turns of the first coil, A=B+E'
We will compensate you accordingly. With conventional bifilar winding,
Although such compensation winding was difficult, it can be easily implemented in this embodiment since it is an independent winding.

FIG. 3 is a block diagram of a second embodiment of the present invention. In this embodiment, the recording/reproducing coil 15' is attached to the bobbin 16'.
This first coil 17' is wound inwardly.
The second coil 19' is disposed so as to surround it, that is, concentrically. However, although the two coils are separated by 9 and the coupling capacitance is reduced, if this continues, the first coil 1
7' and the second coil 19' cannot be considered equivalent, and an asymmetry occurs in the magnetic field generated in the recording/reproducing gap 13. That is, since the gap between the second coil 19' and the recording/reproducing core 4 is large, leakage magnetic flux is large, and the efficiency of emitting magnetic flux to the recording/reproducing gap 13 is poor. Also,
Since the second coil has a large cross-sectional area in the magnetic path, the inductance L should be proportionally large. Furthermore, although the influence is small, the total length of the conductor wire of the second coil becomes longer, the direct current resistance becomes thicker, and the recording current becomes smaller, so that the magnetic flux generated in the second coil 19' becomes smaller. In a magnetic head that requires symmetry of recording magnetic flux in different directions by two coils, in order to avoid the above asymmetry,
The number of turns of the second coil +9' is made larger than the number of turns of the first coil 17', and the difference in the number of turns is appropriately adjusted to make the generated magnetic field symmetrical.

Note that, similarly to the first embodiment, there is a partition 1 between the two coils.
8' or a gap can be provided to adjust the coupling capacitance to a smaller value.

Another aspect of this second embodiment is that two coils 17
', 19' have the same number of turns, and these two coils 17
', +9' and the polarity relationship of the erasing coil If,
The interference of the erase head in the magnetic head of the high-density FDD explained in FIG. 2 is compensated for. In Figure 2, by determining the polarity so that the magnetic flux generated by the first inner coil is A and the magnetic flux generated by the second outer coil is B, the asymmetry between the inner and outer coils is eliminated. This cancels the asymmetry of recording magnetic flux caused by magnetic flux leakage and makes the magnetization of the media symmetrical. In the above, if the asymmetry of the recording magnetic flux cannot be canceled out, the adjustment can be made by changing the number of turns of the two coils 17' and 19'.

FIG. 4 shows the recording current waveform flowing through the recording/reproducing coil during writing. Usually, due to the inductance of the coils, the resistance connected between the two coils is Rw. (Figure 5), the time constant τ of the rise of the square wave is τ=
L/Rw. However, if the coupling capacitance C of the coil is large, overshoot will occur as shown by the dotted line, making recording unstable, which will appear as fluctuations in read data during playback, and become a factor in error occurrence. There is a risk. According to this embodiment, since the coupling capacitance is reduced,
This overshoot can also be reduced, and the above-mentioned error can be prevented.

The above-mentioned rectangular wave recording current has odd-order harmonic components, and low-order harmonics have large energy and are likely to receive crosstalk and cause errors. By moving the resonance point to a point that exceeds 3 to 5 times, it prevents low-order crosstalk, and also prevents crosstalk and noise by moving the resonance point outside the recording/playback area of the recording/playback head. .

It should be noted that the present invention can be applied to various recording devices in line with the gist thereof, and can take various embodiments, such as being applied to a single magnetic head without an erasing core.

[Effects of the Invention] As is clear from the above description, the magnetic head of the present invention can be made resistant to inductive noise by reducing the coupling capacitance, and in a double-sided FDD, crosstalk from the magnetic head on the opposite side can be reduced. You can prevent talk from occurring. On the other hand, overshoot of the recording current waveform is reduced, recording magnetization is stabilized, fluctuations in read data are reduced, and error factors can be reduced. In addition, since there is no need to wind the conductor wires in pairs as in the past, the winding process becomes easier, and the number of turns can be easily changed, making it more asymmetrical than conventional bifilar winding for high-density FDDs. You can get a smaller head.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing a first embodiment of the present invention, and FIG. 2 (
A), (B), and (C) are explanatory diagrams of interference of erasure magnetic flux, 3rd
Figure 4 is a diagram of the configuration of the second embodiment of the present invention, Figure 4 is a recording current waveform diagram during writing, Figure 5 is an equivalent circuit diagram of a conventional magnetic head and recording system, and Figure 6 is a diagram of a conventional coil. It is an explanatory view of bifilar winding. l...Magnetic head, 17.17'...First coil, 19.19'...Second coil, A, B...Recording magnetic flux. 1st Power Great Banner Unprecedented 1 Sum Figure 1 (a) Eliminate the interference of the Sung Dynasty (b) ! L, 70 Figure 4

Claims (4)

[Claims] (1) A magnetic head that includes a first coil and a second coil and alternately generates recording magnetic flux in mutually different directions, characterized in that the first coil and the second coil are arranged independently of each other. magnetic head. (2) The magnetic head according to claim 1, wherein the arrangement is such that the first coil and the second coil are divided in the recording magnetic flux direction. (3) The magnetic head according to claim 1, wherein the arrangement is such that a first coil and a second coil are concentrically overlapped. (4) Claims 1 to 3 above, characterized in that the arrangement is such that a partition or a gap for adjusting coupling capacity is provided at the boundary where the first coil and the second coil touch. A magnetic head according to any of the above.