JPH06111246A - Magnetic head - Google Patents

Abstract

PURPOSE:To provide a magnetic head for suppressing noise in a reproduced screen by reducing the frictional charging amount thereby suppressing discharge noise. CONSTITUTION:A soft magnetic alloy film, i.e., a thin film 7 of sendust (FeAlSi), is deposited on nonmagnetic substrates 8, 9 while being insulated through a nonmagnetic intermediate film (e.g. SiO2 film) thus constituting a multilayer film structure. Magnetic cores are bonded through a gap by means of a bonding glass 5. Crystallized glass A is employed for the nonmagnetic substrate 8 in a head chip 2 whereas crystallized glass B having different composition is employed for the nonmagnetic substrate 9 in a head chip 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic head, and more particularly to a magnetic head such as a combination head mounted on a magnetic recording / reproducing apparatus such as a video tape recorder (VTR).

[0002]

2. Description of the Related Art In a combination head used in a general VTR, two magnetic head chips are closely attached to each other on a head base with an adhesive. V
Coercive force (Hc) such as HS (registered trademark) standard is 650 Oe
In the magnetic head of VTR using iron oxide tape of about
Ferrite is used as the magnetic core material of the magnetic head chip. FIG. 6 is a diagram showing a sliding surface shape of a conventional ferrite chip with respect to a magnetic tape. In the figure, 21 is a ferrite substrate, 22 is a bonding glass, and 23 is a gap. Since the two head chips have the same structure, only one of them is shown. The head chip has a ferrite substrate 21 which is a magnetic core and a non-magnetic bonding glass 2
2 and a gap 23 that is non-magnetic.

Further, the coercive force (Hc) of the S-VHS standard, etc.
In a VTR magnetic head using a high coercive force tape such as an iron oxide tape of about 950 Oe or a metal tape (ME, MP) having a coercive force (Hc) of about 1500 Oe, a metal in-gap head (MIG head) or a thin film laminated head is used. It is used. These correspond to the sendust (Bs) against the saturation magnetic flux density (Bs = 5000G) of ferrite.
= 11,000 G), amorphous (Bs = 8000 or more) soft magnetic alloy film is used for at least a part of the magnetic core so that the high coercive force tape can be recorded sufficiently.

7A to 7D are views showing typical sliding surface shapes of the MIG head. FIG. 7A is a parallel type, FIG. 7B is a Σ type, and FIG. Inclined type, cross type is shown in FIG. In the figure, reference numeral 24 is a soft magnetic alloy film, and other parts having the same functions as those in FIG. 6 are denoted by the same reference numerals. The structure is such that the soft magnetic alloy film 24 is formed on the ferrite substrate 21. 8A and 8B are views showing typical sliding surface shapes of the thin film laminated head, in which FIG. 8A is a laminate type and FIG. 8B is an inclined type. In the figure, 25 is a soft magnetic laminated alloy film, 26 is a non-magnetic substrate, and other parts having the same functions as those in FIG. The soft magnetic laminated alloy film 25 is formed on the non-magnetic substrate 26. Table 1 shows a performance comparison between the ferrite head, the MIG head, and the thin film laminated head. Table 1 shows that the thin-film laminated head is superior to other heads in substrate performance.

[0005]

[Table 1]

The non-magnetic substrate 25 of the thin-film laminated head is mainly made of ceramic or crystallized glass. In particular, when the soft magnetic alloy film 24 is an iron yarn alloy such as sendust, the thermal expansion coefficient α is, for example, 100 ° C. to 70 ° C.
In the range of 0 ° C., it is 160 × 10 ⁻⁷ / ° C., and in the case of a ceramic material, α = 145 × 10 ⁻⁷ / ° C. is the upper limit. Therefore, in order to match the thermal expansion coefficient α with the soft magnetic alloy film as much as possible to reduce the internal stress of the laminated film at the time of film formation and the thermal stress in the head manufacturing process, crystallized glass having a higher thermal expansion coefficient than the ceramic material is used. Is more advantageous.

[0007]

As described above, in the case of a conventional thin film laminated head using crystallized glass, a certain specific tape has a high sliding speed between the tape and the head, which causes the sliding surface of the head to move. In the crystallized glass substrate of, the positively charged electric charge is accumulated by frictional electrification, and when a certain amount is exceeded, electric discharge occurs due to the dielectric breakdown phenomenon of the air between the tape and the head, and the magnetic field generated by the electric discharge causes magnetic discharge. There is a problem that an induced current is generated in the winding of the head and noise (discharge noise) is generated on the reproduction screen.

The present invention has been made in view of the above circumstances, and provides a magnetic head in which noise is not generated on a reproduction screen by reducing the triboelectric charge amount and eliminating the generation of discharge noise. Is intended.

[0009]

In order to achieve the above object, the present invention provides: (1) A plurality of magnetic head chips are arranged in close proximity on a head base, and the magnetic head chips are made of a non-magnetic substrate. In a magnetic head provided on top of which a soft magnetic thin film is formed as a magnetic core, the material of the non-magnetic substrate of each magnetic head chip is a crystallized glass substrate having a different composition, or (2) Of the magnetic head chips are arranged in close proximity to each other on the head base, one of the magnetic head chips has a soft magnetic film formed as a magnetic core on a crystallized glass substrate, and the other has only a ferrite or a ferrite substrate. It is characterized in that a soft magnetic film is formed thereon and is formed as a magnetic core.

[0010]

When two kinds of crystallized glass slide on the tape at the same time, one crystallized glass substrate A and the magnetic tape and the other crystallized glass substrate B and the magnetic tape have different frictional electrification states. The movement behavior of electrons between them becomes complicated, and as a result, the combination head composed of crystallized glass substrates of different compositions is different from the head composed of crystallized glass substrates of the same type. In the entire tape system, the movement of electrons is small, the triboelectric charge amount is small, and the triboelectric charge amount is not enough to cause dielectric breakdown of the air between the tape and the head (the relaxation effect greatly increases the surface accumulated charge amount). Discharge noise does not occur.

[0011]

Embodiments will be described below with reference to the drawings. FIG. 1 is a block diagram for explaining an embodiment of a magnetic head according to the present invention, in which 1 is a head base and 2,
Reference numeral 3 is a head chip, and 4 is a magnetic head. Two head chips 2 and 3 are closely attached to the head base 1 with an adhesive. FIG. 2 is a view showing a sliding surface of the magnetic head shown in FIG. 1, 5 is a bonding glass, 6 is a gap, 7 is a soft magnetic alloy film, and 8 and 9 are non-magnetic substrates. A sendust (FeAlSi) thin film 7, which is a soft magnetic alloy film, is vapor-deposited on non-magnetic substrates 8 and 9, and a non-magnetic intermediate film having a thickness of several thousand angstroms (for example, S
It has a multilayer film structure insulated by an iO ₂ film or the like.
Further, the magnetic core via the gap 6 is joined by the bonding glass 5. The material of the non-magnetic substrate 8 used in the head chip 2 is crystallized glass A, and the material of the non-magnetic substrate 9 used in the head chip 3 is crystallized glass B. Table 2 shows the compositions of the crystallized glasses A and B.

[0012]

[Table 2]

In the magnetic head shown in FIGS. 1 and 2, the track width Tw of the head chip 2 is 58 μm (10 layer laminated film) and the track width of the head chip 3 is 19 μm (4 layer laminated film). The interval X of the gap 6 of the head chip is 740 μm. These dimensions do not have any effect on the effect of the present invention even if they differ from this embodiment.

Next, the head of the present invention and the conventional head are separated by S-
The result of mounting on the VHS stationary VTR will be described.
FIG. 3 is a layout view of the upper drum of the S-VHS VTR. In the figure, 1a and 1b are head bases, 11A to 15B are head chips, and 16 and 17 are ferrite heads. The head chips 11A and 12B and the head chips 11B and 12A attached on the head bases 1a and 1b have a thin film laminated head structure. The symbols A and B indicate azimuth angles, where A is + azimuth (clockwise) and B is −azimuth (counterclockwise). Furthermore, head chip 1
Reference numerals 1A and 11B are standard mode (SP) recording / reproducing dedicated heads, and head chips 12A and 12B are triple mode (EP) recording / reproducing dedicated heads. Other head chips 13A, 13B and head chips 14A, 1
4B is a ferrite head for compatibility reproduction for special reproduction and EP, and head chips 15A and 15B are ferrite heads for FM audio.
7 is a ferrite head (azimuth angle 0 °) for flying erase. Since these head materials are ferrite, discharge noise due to frictional charging does not occur. Thin film laminated head chips 11A, 11B and 12A, 12B
Various S when each is combined by changing the substrate material
Table 3 shows the amount of discharge noise level due to frictional charging with the VHS tape.

[0015]

[Table 3]

The thin film stacking head in each combination is SV
HS VTR (using VCBS500 (made by Sharp))
It was mounted on, the unrecorded tape was reproduced, and the discharge noise level amount was measured with a digital oscilloscope. However, the numerical value is not a perfect absolute value measurement, and changes with time, so the accuracy increases as the number of measurements increases. The data in Table 3 is a relative value comparison of two total values when discharge noise occurs.

Here, the head chips 11A, 11B, 1
Combination of 2A and 12B substrate material and tape A (Test No.
The discharge noise amount of 1) was set to 100%, and other combinations were compared with this. From the results of Table 3, it can be seen that the discharge noise level amount is smaller when the head chip substrate material is different from that of the same type. Next, a pin-on-disk tester was used to directly measure the triboelectric charge amount of the substrate material of the head chip.

FIG. 4 is a block diagram of the measuring device.
Is a disk, 19 is a pin test piece, 20 is a magnetic tape, 2
Reference numeral 1 is a surface electrometer. The substrate material of the head chip was formed into the shape of the disk 18, and the surface was made into a mirror surface 100Å. Disk 18 was a 1 inch disk and was rotated at 150 rpm. A constant load of 50 g was applied to the pin test piece 19. The pin shape is 2 mm square, but 10R is processed in one direction. The magnetic tape 20 was attached to the tip of the pin with double-sided tape and brought into contact with the disk 18. The triboelectric charge amount was measured by positioning the surface electrometer 21 above the disk 18 by 2 to 3 mm. The composite disk of the crystallized glass A and the crystallized glass B was prepared by integrating the bonded pieces at 90 ° intervals as shown in FIG. The results are shown in Table 3. It can be seen that there is a correlation with the amount of discharge noise level. Next, Table 4 shows the results of an examination conducted by changing various tapes. The head according to the present invention has a smaller discharge noise level for all tapes than the conventional head, and further supports the result of the direct measurement of the triboelectric charge amount by the pin-on-disk test.

[0019]

[Table 4]

From the above examination, it was found that the head of the present invention has a small amount of triboelectric charge, and consequently has the effect of suppressing the generation of discharge noise on the VTR. Further, as shown in Table 3, ferrite does not cause triboelectric charging. Therefore, if the head chips of crystallized glass and ferrite are provided on the head base, the same effect can be obtained. However, when the ferrite head is used, the performance of the conventional magnetic head is deteriorated as compared with the thin film laminated head as shown in Table 1. Therefore, it is also possible to use a MIG head, or to use only a ferrite head and combine it with a substrate using ferrite depending on the usage of the head such as dedicated reproduction.

[0021]

As is apparent from the above description, the present invention has the following effects. That is, since the materials of the non-magnetic substrates of the plurality of magnetic head chips are the crystallized glass substrates having different compositions, the triboelectric charge amount becomes small, and the discharge noise does not occur, so that the noise occurs on the reproduction screen. The problem goes away.

[Brief description of drawings]

FIG. 1 is a configuration diagram for explaining an embodiment of a magnetic head according to the present invention.

FIG. 2 is a diagram showing a sliding surface of the magnetic head in FIG.

FIG. 3 is a diagram showing a head arrangement of an upper drum of a VTR equipped with a magnetic head according to the present invention.

FIG. 4 is a configuration diagram of a triboelectric charge amount measuring device by a pin-on-disk test according to the present invention.

FIG. 5 is an explanatory diagram of a composite substrate disk according to the present invention.

FIG. 6 is a diagram showing a sliding surface of a conventional ferrite head.

FIG. 7 is a diagram showing a sliding surface of a conventional MIG head.

FIG. 8 is a diagram showing a sliding surface of a conventional thin film laminated head.

[Explanation of symbols]

1 ... Head base, 2, 3 ... Head chip, 4 ... Magnetic head, 5 ... Bonding glass, 6 ... Gap, 7 ... Soft magnetic alloy film, 8, 9 ... Non-magnetic substrate.

Claims (2)

[Claims] 1. A magnetic head in which a plurality of magnetic head chips are closely arranged on a head base, the magnetic head chips are provided on a non-magnetic substrate, and a soft magnetic thin film is formed as a magnetic core. A magnetic head, wherein the material of the non-magnetic substrate of each magnetic head chip is a crystallized glass substrate having a different composition. 2. A plurality of magnetic head chips are arranged close to each other on a head base, one of the magnetic head chips has a soft magnetic film formed as a magnetic core on a crystallized glass substrate, and the other has the other. A magnetic head characterized in that a soft magnetic film is formed only on ferrite or on a ferrite substrate to form a magnetic core.