JPH05290318A - Rotary magnetic head device - Google Patents

Abstract

PURPOSE:To lessen the change in reproduced output and to eliminate the fluctuation in performance by decreasing the inductance of the magnetic head and lessening the change thereof. CONSTITUTION:The number nHI of turns of a coil 5IC of an I shape core 5I constituting the magnetic head 5CC is set at 2 or 3. The number nHC of turns of a coil 5CC of a C shape core 5C constituting the magnetic head 5 is set at 3 or 2. The total number nH of turns of the coil of the magnetic head 5 is set at 5 and the number nP of turns of the rotor side windings 7a, 7b of a rotary transformer is set at 1. Further, the number nS of turns of the stator side windings 8a, 8b of the rotary transformer is set at 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary magnetic head device for recording a signal on a magnetic tape as a recording medium or reproducing a signal recorded on a magnetic tape,
In particular, DAT (Di
The present invention relates to a rotary magnetic head device suitable for use in a gital audio tape recorder).

[0002]

2. Description of the Related Art Conventionally, since the size of a DAT was close to that of a VTR (Video Tape recorder) at the beginning of development, the VTR specification is used as it is. Figure 3
FIG. 3 is a cross-sectional view showing an example of a rotary magnetic head device used in the above-mentioned DAT. In FIG. 3, reference numeral 1 is a chassis, and 2 is a fixed drum attached to the chassis 1, and an annular recess 2a is formed in the upper portion of the fixed drum 2.

Reference numeral 3 denotes a motor mounted below the fixed drum 2. A shaft 3a of the motor 3 penetrates the fixed drum 2 and projects above the fixed drum 2. Reference numeral 4 denotes a rotary drum fixed to the shaft 3a of the motor 3 protruding from the fixed drum 2, and 5 denotes a magnetic head. The magnetic head 5 is mounted on a mounting substrate 6 mounted on the lower surface of the rotary drum 4, and fixed. The tip of the drum 2 and the rotary drum 4 are slightly projected from the outer peripheral surfaces formed by the outer peripheral surfaces thereof. Although not shown, the magnetic head 5 is provided with coils connected to rotor side windings 7a and 7b of a rotary transformer, which will be described later.

Reference numeral 7 denotes a rotor-side core which constitutes a rotary transformer, which is attached to the lower surface of the rotating drum 4 and is connected to the coil of the magnetic head 5 so that the rotor-side winding 7a,
7b is provided. Reference numeral 8 denotes a stator side core that constitutes a rotary transformer, and is attached to the bottom surface of the recess 2a of the fixed drum 2 so as to face the rotor side core 7 with a slight gap (for example, 30 μm to 50 μm) in order to increase the coupling coefficient. Stator-side windings 8a and 8b are provided at positions facing the rotor-side windings 7a and 7b. Incidentally, T indicates a magnetic tape as a recording medium.

FIG. 4 is a characteristic diagram showing the transfer characteristic of the rotary transformer in the used frequency band. In FIG. 4, a is a step-up ratio obtained by dividing the number of turns n _S of the stator side windings 8a and 8b by the number of turns n _P of the rotor side windings 7a and 7b, E _o is the electromotive voltage of the magnetic head 5, and E _i is input voltage of a reproducing amplifier, f _r denotes the resonant frequency.

Next, the operation will be described. First, when the rotary drum 4 attached to the shaft 3a is rotated by rotating the motor 3, the magnetic head 5 attached to the rotary drum 4 via the attachment substrate 6 also rotates. Then, while the rotary drum 4 and the magnetic head 5 are rotating in this way, the magnetic tape T is run by a tape running mechanism (not shown), and a signal is recorded on the magnetic tape T by the magnetic head 5 or The signal recorded on the tape T is reproduced by the magnetic head 5. In this way, in order to supply a signal to be recorded on the magnetic tape T to the magnetic head 5 from a recording amplifier (not shown), or to supply a signal reproduced by the magnetic head 5 from the magnetic tape T to a reproduction amplifier (not shown). A rotary transformer is used.

Next, the total number of turns (n _H ) of the coil of the magnetic head, the number of turns of the rotor side winding (n _P ) and the number of turns of the stator side winding (n _S ) of the rotary transformer will be described. First, the rotary transformer has less loss,
In addition, it is necessary to have a flat transfer characteristic shown by the solid line in FIG. 4 in the used frequency band. In the case of a VTR, generally, the frequency of the white peak of the video signal and the resonance frequency f _r are generally matched.

Therefore, assuming that the input capacitance of the reproduction amplifier (not shown) is C, the resonance frequency f _r is f _r = 1 / [2π (C · L _SH ) ^1/2 ]. L _SH is the inductance of the impedance of the rotary transformer as seen from the stator side windings 8a, 8b.

Next, the inductance L _SH is L _SH = a ² · L _P [1- [K ² · L _P / (L _H +
L _P )]]. Note that L _P is the inductance of the rotor side windings 7a and 7b of the rotary transformer, L _H is the inductance of the coil of the magnetic head 5, and K is the coupling coefficient of the rotary transformer (usually 0.97 to 0.99, the larger the better). It is). Therefore, since the resonance frequency _fr and the input capacitance C are substantially determined, the inductance L _SH can be determined.

Further, the transfer characteristics of the rotary transformer are as follows: E _i / E _o = <L _SH / {L _P × [1- [K ² · L _P /
(L _H + L _P )]}} ^1/2 × [K · L _P / (L _H + L
_P )], the inductance L _P that maximizes (E _i / E _o ) is L _P = L _H × {1- [1 / (1-K ² )]} ^1/2 , The relationship between the two inductances L _P and L _H can be obtained. Further, the optimum step-up ratio a is expressed as a = (L _SH / L _H ) ^1/2 .

The total number of turns n _H of the coil of the magnetic head 5 satisfying the above relation, and the rotor side winding 7 of the rotary transformer.
a, the number of turns n _P and the stator winding 8a of 7b, but will select the number of turns n _S of 8b, the total number of turns n _H of coil
Is set to about 25, the number of turns n _P of the rotor side windings 7a and 7b is set to 5, and the number of turns n _S of the stator side windings 8a and 8b is set to 1 so that the step-up ratio a is 2.
0, the number of turns n _P of the rotor side windings 7a and 7b is set to 4, the number of turns n _S of the stator side windings 8a and 8b is set to 8, and the number of turns n _P of the rotor side windings 7a and 7b is set. The number of turns n _P is set to 3, and the stator side winding 8a,
It is common to set the winding number n _S of 8b to 6.

[0012]

The conventional rotary magnetic head device is constructed as described above, that is, since the numbers of turns n _H , n _P and n _S are set as described above, the magnetic head 5 Total number of coil turns n _H
Must be around 25. In order to apply the total number of turns n _H of the coil of the magnetic head 5 in this manner, it is necessary to pass the wire rod 25 times forward and backward through a narrow gap like a hole of a needle. It is currently used.

The total number of turns n of the coil of the magnetic head 5 is n.
_It usually takes 3 to get used to the manual work of applying _H about 25 times.
It takes about a month. In addition, in order to form the coil of the magnetic head 5 with an automatic winding machine, precise and expensive equipment is required, and as a result, it costs more than manual work. Therefore, there is an inconvenience that the rotary magnetic head device becomes expensive because the magnetic head 5 becomes expensive.

Therefore, in the case of a rotary magnetic head device used for DAT, which is less affected by S / N, it is conceivable to reduce the total number of turns n _H of the coil of the magnetic head 5 to increase the step-up ratio a. The applicant of the present application has proposed a rotary magnetic head device satisfying such conditions.
I proposed it as 738.

FIG. 5 is a diagram showing a combination of the conventional characteristics and the number of windings which does not largely change in the rotary magnetic head device previously proposed by the present applicant. The number of turns n _H shown in FIG.
In the combination of n _P and n _S, the rotary transformer is difficult to make in the combinations (4) and (5).
Need to be excluded. Thus the combination (4),
In the case of the combination (3) excluding (5), the total number of turns n _H of the coil of the magnetic head 5 is the smallest and the step-up ratio a is also the largest, so that the characteristics of the magnetic head 5 are not degraded. It can be said that the combination can minimize the total number of turns n _{H of the} coil.

However, in the rotary magnetic head device previously proposed by the applicant, the total number of windings n _H of the coil of the magnetic head 5 is n _H.
Since the number of turns of the coil of the I-type core and / or the C-type core constituting the magnetic head 5 is not taken into consideration, the total number of turns n _H of the coil of the magnetic head 5 is 5, the number of turns of the coil of the I type core and C
Magnetic head 5 when the number of turns of the coil of the mold core can be taken
The inductance L _H has a value shown in the characteristic diagram of FIG. In addition, in FIG. 2, Δ is a plot point of 0.5 MHz,
◯ indicates a plot point of 4.7 MHz.

Therefore, in the rotary magnetic head device previously proposed by the applicant, the number of turns of the coils of the I-type core and the C-type core constituting the magnetic head 5 cannot be specified.
As you can see from the characteristic diagram of, the change in the playback output is large,
There is a possibility that the performance may vary and the performance may be deteriorated. Since the input capacitance C is determined by the reproduction amplifier, it is desirable that the inductance L _H of the magnetic head 5 be small.

The present invention has been made in order to eliminate the above-mentioned inconvenience, and reduces the inductance of the magnetic head, and also reduces the change in the read output to reduce the change in reproduction output, resulting in variation in performance. A non-rotating magnetic head device is provided.

[0019]

In order to achieve the above-mentioned object, the rotary magnetic head device according to the present invention has the number of turns of the coil of the I-shaped core constituting the magnetic head is 2 or 3, and the magnetic head is The number of windings of the coil of the C-shaped core is set to 3 or 2, the total number of windings of the coil of the magnetic head is set to 5, the number of windings of the rotor side winding of the rotary transformer is set to 1, and the winding of the stator side winding of the rotary transformer is set. The number of turns of is set to 10.

[0020]

Since the rotary magnetic head device according to the present invention is constructed as described above, the inductance of the magnetic head becomes small as can be seen from the characteristic diagram of FIG.

[0021]

Embodiments of the present invention will be described below with reference to the drawings.
To do. FIG. 1 shows the structure of a magnetic head according to an embodiment of the present invention.
It is an explanatory view showing composition. In FIG. 1, 5 is a magnetic head
Do 5,_IIs an I-shaped core 5 that constitutes the magnetic head 5. _CIs a magnet
The C-shaped core forming the air head 5 is shown, and the I-shaped core 5 is shown._ITo
Is the number of turns n_HICoil 5 with 2 (or 3)_{I c}Rolled
C type core 5_CThe number of turns is n_HCWas set to 3 (or 2)
Coil 5_CCIs wound, and the total number of turns of the coil is n_HIs 5
There is.

FIG. 2 is a characteristic diagram showing changes in inductance when the number of turns of the coil of the I-type core and the number of turns of the coil of the C-type core are changed with the total number of turns of the magnetic head being 5. In Fig. 2, △ is the plot point of 0.5 MHz, and ○ is 4.
Plot points at 7 MHz are shown.

Constituting the magnetic head 5 as described above
As shown in the characteristic diagram of FIG.
Inductance L_HCan be a small value.
Therefore, as in the above-described embodiment, each winding number n_HI，
n_HC, N_H, N_PAnd n _SBy setting
Inductance L of the air head 5_HBecomes smaller
, The change is reduced and the change in playback output is reduced.
Therefore, there is no variation in performance.

The number of turns n _{P of the} rotor side windings 7a and 7b
Therefore, it is preferable to use flatly pressed windings as the rotor side windings 7a and 7b.

[0025]

As described above, according to the present invention, the number of turns of the coil of the I-type core that constitutes the magnetic head is 2 or 3.
In addition, the number of turns of the coil of the C-shaped core constituting the magnetic head is set to 3 or 2, the total number of turns of the coil of the magnetic head is set to 5, and the number of turns of the rotor side winding of the rotary transformer is set to 1, Since the number of windings on the stator side winding of the rotary transformer is set to 10, there is an effect that the inductance of the magnetic head is reduced, the change is reduced, the change in the reproduction output is reduced, and there is no variation in performance.

[Brief description of drawings]

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

FIG. 2 is a characteristic diagram showing a change in inductance when the number of turns of the coil of the I-type core and the number of turns of the coil of the C-type core are changed with the total number of turns of the magnetic head being 5.

FIG. 3 is a cross-sectional view showing an example of a rotary magnetic head device.

FIG. 4 is a characteristic diagram showing a transfer characteristic of a rotary transformer in a use frequency band.

FIG. 5 is a diagram showing combinations of the conventional characteristics and the numbers of turns that do not significantly change in the rotary magnetic head device previously proposed by the applicant.

[Explanation of symbols]

2 Fixed drum 3 Motor 4 Rotating drum 5 Magnetic head 5 _I I type core 5 _IC coil 5 _C C type core 5 _CC coil 6 Mounting board 7 Rotor side core 7a, 7b Rotor side winding 8 Stator side core 8a, 8b Stator side Winding

Claims (1)

[Claims] 1. A rotary magnetic head device comprising a rotating magnetic head, the coil of which is connected to a rotor side winding of a rotary transformer, wherein the number of turns of the coil of an I-shaped core constituting the magnetic head is 2
Or 3 and C that constitutes the magnetic head
The number of turns of the coil of the die core is set to 3 or 2, the total number of turns of the coil of the magnetic head is set to 5, the number of turns of the rotor side winding of the rotary transformer is set to 1, and the number of turns of the stator side winding of the rotary transformer is set. The rotating magnetic head device is characterized in that the number of turns is set to 10.