JPS6031008B2 - High frequency characteristic compensation method in hole head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for compensating high frequency characteristics in a Hall head.

Hall heads that use semiconductors such as lnSb (indium antimony) as thin-film Hall elements utilize the Hall effect, a phenomenon in which electrons in a solid react to magnetism and generate voltage, and have the following characteristics: ing.

'1' Since the output is proportional to the residual magnetic flux of the tape (magnetic flux response type), the output does not change depending on the frequency unlike a head using a coil, and for example, a large output can be obtained even at extremely low frequencies. It will be done.

■ Since the output impedance is purely resistive and has no inductance component, the waveform will not be distorted even for signals that change sharply, providing good transient response.

For magnetic recording and reproducing devices such as tape recorders, standards have been established for recording and reproducing characteristics.

For example, the standards mentioned above include NAB (NatioMIAssoc), which has been adopted in Japan for a long time.
There is a standard for broadcasting (RS), and tape recorders often record in accordance with the above-mentioned NAB standard. FIG. 1a shows the NAB curve, which is the recording characteristic defined by the above-mentioned NAB standard.

When this is reproduced using a conventionally used coil head with a coil wound around a head core, the basic reproduction frequency characteristic of the coil head is an octave curve as shown in Figure 1b. When the above NAB curve is reproduced, it becomes as shown in FIG. 1c. Here, it can be said that the above-described coil head has good high frequency characteristics during reproduction. Also, if we consider the case of reproduction with a hole head, the basic reproduction frequency characteristic in this case is a flat characteristic as shown in Figure 1d, so N
When the AB curve is reproduced, a reproduction characteristic as shown in FIG. 1e is obtained. Therefore, since the high frequency characteristics of the hole head are not very good, it is necessary to compensate for the above-mentioned Takagi frequency characteristics, and a countermeasure against warpage is desired.

The present invention has been made to improve the high frequency characteristics of the above-mentioned hole head, and the output from the coil wound around the yoke is boosted by a step-up transformer, and phase compensation is performed to improve the Takagi frequency characteristics. By subtracting the coil output and the Hall output with good low frequency characteristics obtained from the Hall element formed in the Hall element part, the low frequency characteristics and Takagi frequency characteristics are improved. The purpose of this invention is to provide a method for compensating the Takagi characteristic in a Hall head which can obtain good output.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 2 is a schematic diagram of a Hall head device showing an embodiment of the Takagi characteristic compensation method according to the present invention.

A Hall head with a Hall element interposed in the rear gap is composed of a front chip 2 in which a front gap 1 is formed, a yoke part 3 and a Hall element part 4 forming the rear chip, as shown in the figure. The above Hall element part 4
A Hall element 5 made of lnSb is interposed as a thin film Hall element. In addition, the yoke portion 3
The portion joined to the Hall element 5 is formed into a spire shape in order to concentrate the magnetic flux. Note that 6 indicates a magnetic path of a magnetic circuit formed by the above-mentioned front chip and IJ chip. Reference numeral 7 denotes a coil wound around a part of the magnet of the yoke portion 3, and 8 a step-up transformer, which also serves to compensate the phase of the output signal taken out from the coil 7.

T, ~T,' is the output signal Vc from the transformer 8 which also serves as booster and phase compensation, that is, from the coil 7.
The terminals T2 to T2' are terminals from which the output signal VH from the Hall element 5 is taken out. Therefore, the magnetic flux passing through the rear gap (the joint surface between the steeple-shaped part of the yoke part 3 and the Hall element 5) is nt, and the abutting area of the yoke part 3 with the Hall element 5 is S. Then, the magnetic flux density B is expressed as follows.

B: t '11 where ■■ is important. Therefore, as shown in Fig. 2, a coil 7 is wound around the yoke part 3, and the signal output from the coil 7 is passed through a transformer 8 which also serves as booster and phase compensation. If the coil 7 is taken out, the coil output Vc from the coil 7 will be as follows.

t'21at of 2 capes in VC=-a←group)=-Furthermore, the Hall output VH from the Hall element 5 is as follows.

VH: R-B raw = R-Sin's t '3' In the above formula, R is the Hall constant, 1 is the bias current of the magnetic field applied to the Hall element 5, and d is the film of the Hall element 5. It is thick.

Here, if the transformer 8 described above also serves as phase compensation, L,
Conjecture: The ribs in coil 7 - foundation edition ■ do os's t = ■ os
Because it is in (no t 19 bi), Ho - Female Ka vH = Ki Misaki Hada t
Since a phase plexus occurs between the two and
This means that 20 of c = 1 is equivalent to t of in.

That is, as for mechanical mechanics, the system is such that a coil 7 wound around the yoke portion 3 performs first-order differentiation, and a transformer 8 performs second-order differentiation. The above coil output Vc: [Formula 2' and Hall output VH: In the glue type, the phase difference of the output is eliminated. Therefore, as shown in FIG. By subtracting the output Vc and the Hall output VH, the output terminal 10 of the subtraction circuit 9 is
'This produces the following output eo.

e.

= Trunk (VH-VC) = Harm (Vessel ~ 2) ■ OSin's t
'4' Above side expression 'Ko te'ma, (t of Uke-ki Misaki n) Elbow-
This is due to the power consumption, and the output voltage 20 (t) is due to the coil output Vc.

That is, an output with good low frequency characteristics can be obtained from the Hall output VH, and an output with good Takagi frequency characteristics can be obtained from the coil output Vc. By appropriately selecting the level of the coil output Vc according to the number of turns of the coil 7 wound around the yoke part 3 and the number of turns of the transformer 8, the level of the coil output Vc can be combined with the Hall output VH to act as a pseudo equalizer. It is also possible to do so.

As described above, according to the present invention, a coil is wound around the yoke portion of a hall head, and the signal output obtained from the coil is extracted as a coil output via a transformer that also serves as a step-up and phase compensation. The structure is such that the Hall output obtained from the Hall element in the Hall element section is subtracted, so the coil output produces an output with good Takagi frequency characteristics, and the Hall output produces an output with good low frequency characteristics. It is possible to provide a high-frequency characteristic compensation method for a Hall head that can obtain both of the following characteristics and improve the high-frequency characteristics in addition to the good low-frequency characteristics that are characteristic of the Hall head. can.

[Brief explanation of the drawing]

Figure 1a shows the NAB curve, b and c show the reproduction characteristics of a conventional coil type head, and d. e is a diagram showing a comparison of the reproduction characteristics of the Hall head, FIG. 2 is a schematic configuration diagram of a Hall head device showing an embodiment of the Takagi characteristic compensation method according to the present invention, and FIG. 3 is an embodiment of the subtraction circuit. FIG. 1: Front gap, 2: Front chip, 3: Yoke part, 4: Hall element part, 5: Hall element, 6: Magnetism, 7:
Coil, 8: Step-up and phase compensation transformer, 9: Subtraction circuit, 10: Output terminal, Vc: Coil output, VH: Hall output. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1 In a Hall head with a Hall element interposed in the rear gap, a coil is wound around the yoke, the output obtained from the coil is taken out as a coil output via a step-up and phase compensation transformer, and the coil output and Hall 1. A method for compensating high frequency characteristics in a Hall head, characterized in that the high frequency characteristics are compensated by subtracting the Hall output from a Hall element formed in the element section.