JP3039958B2 - Rotating magnetic head device - Google Patents

Description

The present invention relates to a rotary magnetic head device used for a VTR (video tape recorder), a DAT (digital audio tape recorder), and the like, and a step-up transformer used for the same. Things.

[Prior Art] FIG. 7 (a) is a sectional view of a main part of a rotary cylinder of such a rotary magnetic head device, (b) is a plan view, and (c) is a perspective view.

In the figure, 1 is a magnetic head, 1 'is a head base, 2 is a rotating drum, 2' is a fixed drum, 3 is a relay plate (rotor side), 4 is a rotor core (hereinafter sometimes simply referred to as a rotor), 5 Is a rotating shaft, 6 is a relay plate (stator side), 7 is a slip ring, and 8 is a stator core (hereinafter, referred to as a stator core).
9 is a slip ring brush, 12 is a ball bearing, and 13 is a disk. here,
A rotary transformer is constituted by the rotor core 4 and the stator core 8.

As can be seen in the figure, the rotating shaft 5 is fixed drum 2 '.
It is supported rotatably. A disk 13 is fitted and fixed to the upper part of the rotating shaft 5. A rotating drum to which the magnetic head 1 is fixed is fixed to the disk 13, and a rotor core 4 as a component of a rotary transformer is adhesively fixed to the lower end of the disk 13 coaxially with the rotation axis.

On the other hand, the stator core 8 as the other component of the rotary transformer is fixed to the fixed drum 2 ′ by bonding or the like coaxially with the rotary shaft 5.

A drive motor 50 is attached to the lower part of the rotating shaft 5 (the lower part of the fixed drum 2 ') to obtain a driving force (rotational force). Electrical connection between the magnetic head 1 attached to the rotating drum 2 and the rotor 4 constituting the rotating transformer is made via pin terminals 31 and 32, amplification circuit substrates 33 and 34, and the like.

The rotary transformer composed of the rotor 4 and the stator 8 generally has the same number of coils as the number of the magnetic heads 1 arranged in a groove formed on the surface of a magnetic material core constituting the rotor or the stator. The grooves provided in the magnetic core as the stator 8 are concentrically opposed to each other to transmit a signal between the coils. The opposed rotor (magnetic core) 4 and stator (magnetic core) 8 Is about 10 to 60 μm.

Although not shown individually, the amplifying circuit boards 33 and 34 are provided with an inductance element, a resistance element, an integrated circuit element, a capacitance element, a diode, and the like, which are mounted by soldering.
1 is a step-up transformer, 342 recording integrated circuit element,
Reference numeral 343 denotes a reproduction integrated circuit element. In particular, amplifier circuit board 3
Numeral 4 has conductor patterns on both surfaces and is connected to the various elements.

A slip ring 7 for supplying power to the amplification circuit provided in the rotating body and for supplying a control signal is provided above the rotating shaft. Is attached. Although not shown, the connector 9 'is connected to the slip ring brush 9, and is used for connection to an external circuit.

The slip ring and the amplifier circuit board 34 are connected by a lead wire 71.

Although not shown, the relay board 6 connected to the stator of the rotary transformer is connected to an external circuit via a connector 6 '.

FIG. 8 shows a step-up transformer 341 which is an inductance element connected between the magnetic head and the amplifier circuit.
It is a perspective view which shows the form. This is outer diameter φ4mm inner diameter φ2mm
A 1.5 mm thick ring-shaped Ni-Zn ferrite core 3410 is provided with a toroidal winding 3411 having a wire diameter of 0.16 mm and bonded to a resin base 3412 having a terminal 3413, and a winding terminal is connected to the terminal. By applying a bifilar winding that arranges the coil uniformly over the entire circumference of the core, the coupling coefficient can be easily increased to 0.99 or more, and the capacitance between the primary coil and the secondary coil is also 5 pF.
The outer dimensions were about 6.9 × 6.0 × 3.8 mm. The number of turns at this time is 7μ in 8 turns.
Presents 21μH at H or 14 turns, step-up ratio is 1.5
In ~ 2, when a secondary tap was provided with an intermediate tap for arranging two systems, only a space of about φ1 mm remained on the inner diameter side and automatic winding could not be performed.

FIG. 10 is a block diagram showing a connection as an electric circuit of the rotary magnetic head device shown in FIG. As described above, Japanese Patent Application Laid-open No. Sho 57-86104 discloses a head signal switching method, which describes a conventional technique of a rotary magnetic head device having an amplification circuit built in a rotary drum. "Drum device of magnetic recording / reproducing machine" and the like.

[Problems to be Solved by the Invention] In the above prior art, for example, an erasing head is mounted in a rotating drum as shown in FIG. 10, and a toroidal winding is mounted on a ring-shaped ferrite core as shown in FIG. The rotary magnetic head device in which the step-up transformer, which has just been applied, is connected to the amplifying circuit and arranged in the rotary drum has the following problems.

At the time of recording, an erasing signal having a high signal level leaks to another channel having a step-up transformer, and S / S representing the ratio between the main signal and the leaked signal of that channel.
It was easy to give interference which deteriorated N ratio.

However, irrespective of the presence or absence of the erasing head, a rotating magnetic head device in which a step-up transformer simply applying a toroidal winding to a ring-shaped ferrite core is connected to an amplifier circuit and arranged in the rotating drum is described below. Had problems.

In the step-up transformer, since the toroidal coil provided on the outer periphery of the ring-shaped magnetic body was exposed, electromagnetic induction noise from the outside of the rotary cylinder was easily guided into the coil.

In the step-up transformer, in order to reduce noise due to the leakage signal for erasing and an external induction magnetic field, the step-up transformer is formed of a magnetic material.
In the case, it is advisable to enclose the container, but the price is high and the size is large.

In the step-up transformer, it is necessary to perform winding called bifilar winding in order to increase the coupling coefficient. Therefore, the coil must be uniformly arranged around the circumference of the ring-shaped core. Considering automatic winding by a machine, the inner diameter of the ring core is restricted, and the size of the ring core limits the size reduction.

In order to reduce the size of the step-up transformer, an electric circuit as shown in FIG. 10 is formed by using a multilayer inductance element as shown in JP-A-67-47010, “Method of Manufacturing Chip Inductance”. Although it may be configured, simply using the multilayer inductance element has the following problems.

It is extremely difficult to make the coupling coefficient indicating the coupling state between the primary coil and the secondary coil of the step-up transformer approximately equal to that of a conventional ring core with a bifilar wound toroidal coil. Was. This is due to the structure of the magnetic circuit, which is also a structural defect of the multilayer inductance, and is due to the fact that conductor coils cannot be arranged evenly over the entire area of the magnetic circuit as in a conventional toroidal coil. .

Due to the necessity of miniaturization and the structural defect of the multilayer inductance, the coil conductors are limited due to the spatial restriction due to the configuration that the conductor coils cannot be arranged evenly over the entire magnetic circuit. Since the distance between the conductors of the coil conductor is significantly shortened, the capacitance between the conductors of the coil conductor increases, so that there is a large distributed capacitance in addition to the inductance between the terminals as the inductance element. . This distributed capacity deteriorates the characteristics of the transmission characteristics of the step-up transformer in a high frequency band.

In order to improve the coupling coefficient indicating the coupling state between the primary coil and the secondary coil of the step-up transformer, it is only necessary to reduce the leakage of magnetic flux in the main magnetic circuit constituting the transformer. As a result, the distance between the primary coil and the secondary coil is reduced due to the spatial restrictions caused by the inability to arrange conductor coils uniformly over the entire area of the magnetic circuit, which is also a structural defect of the laminated inductance. If it is possible to reduce the leakage of the magnetic flux,
Since the distance between the coil conductors is further shortened, the distributed capacitance between the coils has a contradictory relationship.

An object of the present invention is to provide a rotary drum of a rotary magnetic head device having dimensions regulated by various standards, a plurality of magnetic heads arranged under multifunctionality, and amplifying signals from the magnetic heads. Amplifying circuit that incorporates a reproducing amplifier circuit that performs amplification and a recording amplifier circuit that amplifies a recording signal, and overcomes the problems of the related art, and provides a high-performance, high-performance, miniaturized, low-cost, step-up transformer. And a rotating magnetic head device used and connected between the magnetic head,
It is to provide such a step-up transformer itself.

[Means for Solving the Problems] To achieve the above object, in a first rotating magnetic head device according to the present invention, a fixed drum having a tape guide surface, and a rotatably inserted support supported on an axis of the fixed drum. A rotating drum having a plurality of magnetic heads attached to the rotating shaft via a mounting member, a rotor core attached to the rotating drum, a stator core attached to the fixed drum, and the core inserted through a slight gap. A rotary amplifier for receiving and transmitting signals in an opposed arrangement, connected to the rotary transformer, and having a reproducing amplifier circuit for amplifying a signal from the magnetic head and a recording amplifier circuit for amplifying a recording signal in a rotary drum; A rotary magnetic head device having a built-in step-up transformer connected between the amplifier circuit and the magnetic head; Yl conductor was thereby enclosing of a magnetic member.

For example, in a step-up transformer of a type in which a toroidal coil is provided on the outer periphery of a ring-shaped core, almost all the circumference is surrounded by a shield member made of a magnetic material except for a terminal portion to which a coil terminal is connected, Except for only the terminal portion to which the coil terminal is connected on the connected amplifier circuit board, the lid is covered with a bowl-shaped shield member made of a magnetic material.

Further, even when the first rotary magnetic head device according to the present invention has at least one erasing head among the plurality of magnetic heads, in the above-described rotary magnetic head device, the main component of the step-up transformer is also provided. The coil conductor is surrounded by a magnetic member.

In the second rotating magnetic head device according to the present invention,
In the rotary magnetic head device as described above, as another means for surrounding the main coil conductor of the step-up transformer with a magnetic member, a laminated type embedded and embedded in the magnetic member of the main coil conductor is used. The step-up transformer is constituted by the inductance element. In the laminated inductance element, the area of the magnetic member portion surrounded by the coil conductor in the cross section perpendicular to the lamination direction of the coil conductor is smaller than that of the coil member in the magnetic member portion constituting the main magnetic circuit. It is configured to be smaller than the area of the magnetic member outside the conductor. In the second rotating magnetic head device, the coupling coefficient between the primary coil and the secondary coil of the step-up transformer is set to 0.970 or more.

In the second rotary magnetic head device, a limit value is set for a distributed capacitance between the coil conductors of the step-up transformer, and a capacitance value between the primary coil and the secondary coil is set as one parameter to 14 pF or less. And

Further, it is determined that both the coupling coefficient and the capacitance between the primary coil and the secondary coil of the step-up transformer satisfy the above-mentioned limit values at the same time.

Further, in the coupling coefficient and the capacitance between the primary coil and the secondary coil of the step-up transformer, the above-mentioned limit value is simultaneously satisfied, and the limit value is also provided for the external dimensions.

[Operation] Coils disposed in grooves provided in the plane of opposing magnetic bodies (rotor core and stator core) in a rotary transformer used in a rotary magnetic head device that does not incorporate an electric amplification circuit in a rotary drum. A signal is transmitted and received between the conductors for the coil. The number of turns of the coil conductor is determined to be an optimum value depending on the constants of the magnetic head and the electric circuit to be connected. Matsushita Electric Industrial Co., Ltd., August 1972 Monthly Magazine: “National Technical Report”, Vol. 18, No. 4, (National Technical Report, vol. 18, No. 4, Aug. 1972)
"Rotating transformers" (Sakata, Tanaka) and the like.

The rotary transformer generally has the same number of coils as the number of magnetic heads, and the number of grooves formed on the surface of the magnetic material core is equal to or greater than the number of coils. By increasing the number of magnetic heads with dedicated functions provided under multifunctionalization, the facing area per groove in the rotary transformer decreases, the coupling coefficient etc. decreases, and the transmission efficiency deteriorates. Become. As a method of compensating for the deterioration of the transmission efficiency of the rotary transformer, an electric amplifier circuit is built in the rotary drum to amplify a reproduced signal generated in the magnetic head and amplify a recording signal supplied to the magnetic head. This is intended to improve the performance, and is disclosed in Japanese Patent Application Laid-Open No. 57-30104.

Between the magnetic head and the amplifier circuit, for example, to adjust the electric constant such as impedance of the magnetic head when viewed from the amplifier circuit side, or to increase the voltage or the like generated in the magnetic head, A step-up transformer is connected, and this step-up transformer can be obtained by simply applying a toroidal winding to a ring-shaped ferrite core and exposing the coil or molding it with a resin or the like. It was common but not magnetically shielded.

Since the step-up transformer boosts a voltage or the like from the viewpoint of its function, it also increases various inductive noises from outside that enter this portion. Also, due to the configuration of the step-up transformer, a magnetic member is used. Depending on the surrounding conditions, the step-up transformer also has a property of converging the external electromagnetic induction magnetic field and the like to the magnetic member.

Therefore, magnetically shielding the step-up transformer itself is an effective means for suppressing the above various external noises.

Further, regarding external induction noise, when a source of the noise is provided inside the rotary cylinder body, for example, when one groove in the rotary transformer is used for erasing,
This is a particularly effective means.

As described above, when the number of magnetic heads is large, the transmission efficiency of the rotary transformer deteriorates. Therefore, a signal having a higher signal level than other signals (video signal, audio signal, etc.) such as an erasure signal is rotated. The magnetic field level generated even in the transformer section becomes higher, and the magnetic flux level leaking from the rotary transformer section becomes higher in conjunction with the deterioration of the coupling coefficient, and it is restricted that the signal tends to be harmful to other signals. In the case where a plurality of magnetic heads, amplifier circuits, and the like are built in the space, it will be understood that distance factors are also taken into account.

Magnetically shielding the step-up transformer itself is an effective means for suppressing various types of external noise as described above, but it has a unified standard like a VTR and has a rotating cylinder. Since there is also a limitation on the size of the drum, it is necessary to reduce the size of the step-up transformer.

When a step-up transformer is constituted by a laminated inductance element to satisfy this requirement, a small-sized step-up transformer that does not particularly require an external magnetic shield member can be obtained.

The laminated inductance element covers the coil with a magnetic material in order to arrange the coil conductor inside the magnetic material because of its structure. However, if consideration is given to a cross-sectional configuration in which the area of the inner part of the coil conductor is smaller than that of the area between the coil conductors, the noise due to the externally induced electromagnetic field is smaller than that of the magnetic circuit due to the magnetic resistance of the magnetic circuit. Since the magnetic flux mainly passes through the outside of the coil and the magnetic path, noise is less likely to be induced in the coil, and the intrusion of noise due to an externally induced magnetic field can be suppressed.

However, compared to the conventional type using a ring core, the laminated type inductance element has a primary coil and a secondary coil as a restriction from the point that the conductor coil cannot be arranged uniformly over the entire area of the magnetic circuit. There is a disadvantage that the engagement coefficient indicating the coupling state between the coils cannot be increased.

However, the relative magnetic permeability of the portions other than the conductors that do not constitute the main magnetic circuit is brought close to 1 as much as possible, or the dimensional accuracy of the laminated portion of the coil conductor and the magnetic layer is increased, so that the boundary between the coil conductor and the main magnetic circuit is reduced. For example, to clarify the change in permeability of the part, the primary coil and the secondary coil overlap over the entire magnetic circuit as much as possible, like bifilar winding used in conventional toroidal coils. As a result of using means for reducing the leakage magnetic flux, such as maintaining the coupling coefficient, the coupling coefficient could be made 0.970 or more.

If the coupling coefficient of the laminated type step-up transformer is 0.970 or more, even if it is relatively easy to make the coupling coefficient 0.99 or more by applying bifilar winding to the conventional toroidal coil type, its transmission is higher. The characteristics can be made substantially equal.

However, in the stacked step-up transformer, 1
Set the coupling coefficient, which indicates the coupling state between the secondary coil and the secondary coil, to 0.
If the above measures are simply taken to achieve 970 or more, it is also a structural defect of the laminated inductance, and the space resulting from the structure where it is not possible to arrange the coil conductors uniformly over the entire area of the magnetic circuit In addition to the physical restrictions, the distance between the coil conductors is physically small, and the distributed capacitance between the conductors is increased, resulting in a large distributed capacitance in addition to the inductance between the terminals as an inductance element. However, the capacitance value between the primary coil and the secondary coil as one parameter representing the distributed capacitance becomes 14 pF or more, and the transmission characteristics in a high frequency band of 5 MHz or more deteriorate.

Therefore, by setting the distance between the coil conductors to an appropriate value or more, the coupling coefficient indicating the coupling state between the primary coil and the secondary coil is set to 0.970 or more, and the static coupling between the primary coil and the secondary coil is increased. The capacitance value can be reduced to 14 pF or less, and the transmission characteristics can be made equal to those of the conventional type.

Further, by increasing the magnetic permeability of the ferrite material constituting the magnetic circuit of the multilayer inductance element, the coil 1
Since the inductance value per unit can be increased, the external dimensions can be reduced without increasing the number of turns of the coil, the number of circuit elements that can be mounted in the rotating drum can be increased, and multi-functionality can be achieved. It is possible to realize the mounting of the amplifier circuit inside.

Example Next, an example of the present invention will be described with reference to the drawings.

FIG. 1 (a) is a sectional view of a main part of an embodiment of a rotary cylinder of a rotary magnetic head device according to the present invention, (b) is a plan view thereof, and (c) is a perspective view thereof. In FIG.
The same or corresponding components as those in the drawings are denoted by the same reference numerals.

That is, in FIG. 1 (a), it is shown that the step-up transformer 341 connected and mounted on the amplifier circuit boards 33 and 34 is of a small type in which a main coil conductor is surrounded by a magnetic member. I have.

The connection diagram of the electric circuit is as shown in FIG. 10, and shows a case where an erasing head is mounted as one of the plurality of magnetic heads 1 in the rotating drum 2.

In the figure, 1 is a magnetic head, 1 'is a head base, 2 is a rotating drum, 2' is a fixed drum, 3 is a relay plate (rotor side), 4 is a rotor core, 5 is a rotating shaft, and 6 is a relay plate (stator). 7) is a slip ring, 8 is a stator core, 9 is a slip ring brush, 12 is a ball bearing, and 13 is a disk. Here, the rotor core 4 and the stator core 8
Constitutes a rotary transformer. This figure does not accurately show the grooves provided in the core and the signal transmission coils and the like provided in the grooves.

The slip rings 7 and 9 supply a power supply of an amplifier circuit arranged in the rotating drum and a control signal for reproduction / recording timing and the like. Various signals transmitted to the slip ring 7 are connected to the amplifier circuit board 34 by the lead wire 71.

Electrical connection to another amplifier circuit board 33 is made by the pin terminals 32 and the like, and furthermore, it is also connected to the relay plate 3 to which the lead ends of the coils arranged on the rotor core 4 are led.

Electrical connection between the magnetic head 1 and the amplifier circuit board 33 is achieved by the pin terminals 31.

Although detailed conductor patterns are not shown on the surface of each of the amplifier circuit boards 33 and 34, the step-up transformer 341 and the
In addition to the recording integrated circuit 342 and the reproducing integrated circuit 343, an inductance element, a resistance element, a capacitance element, a diode, and the like are soldered.

Each of the amplifier circuit boards 33 and 34 is mounted on the disk 1 with screws or the like.
3, fixed to the rotating drum 2. Amplification circuit board 34
Has a circuit on both sides, and if it uses an iron substrate having an insulating coating on its surface, it functions as a magnetic shield plate in a rotating drum.

FIG. 9 shows a magnetic head 1 of a rotary cylinder according to the present invention.
Shows the arrangement on the rotating drum 2. In FIG. 1, reference numeral 10 denotes a magnetic tape wound around the outer periphery of the rotary drum 2 and in contact with the magnetic head 1. The symbols (+) and (-) in the figure indicate the azimuth angle of the operating gap of the magnetic head, PM is for playback monitoring, REC is for recording, PB is for playback, HiFi is for audio, FE
Indicates a function for erasing or the like.

The PM head for reproduction monitoring works simultaneously with the REC head for recording, reproduces the signal recorded on the magnetic tape without rewinding the tape, and instantly checks the operation of the REC head. The PB 'head is also used for special reproduction in which reproduction is performed at a tape feed speed different from the tape feed speed at the time of recording in combination with another PB head. Hi
The Fi head functions for recording / reproducing audio signals. RE
The C / PB head functions for recording / reproducing a video signal.
The FE head functions for erasing video and audio signals.

FIG. 2 is a perspective view of a step-up transformer according to an embodiment of the present invention. FIG. 2 (a) shows a type in which a toroidal coil 3411 is provided on the outer periphery of a ring-shaped core 3410, to which a coil terminal is connected. Except for the terminal portion 3413, a shield member 3419 made of a magnetic material surrounds the entire circumference,
(B) shows another embodiment in which the shield member 3419 does not surround the entire circumference, but is simply covered with a shield member on the bowl.

FIG. 3 is a perspective view showing the appearance of an embodiment of the step-up transformer 341 relying on the multilayer inductance element of the present invention, and the terminal symbols in the figures correspond to those in FIGS. 2 and 8 and are the same. The code is attached. Symbols in FIGS. 2 and 3 correspond to in the circuit symbol diagram.

FIG. 4 is a cross-sectional view of a main part of a step-up transformer using the multilayer inductance element of the present invention shown in FIG. 3, wherein (a) shows a primary coil conductor between secondary coil conductors. FIG. 3B shows an example in which the primary coil conductors are evenly arranged between the secondary coil conductors. The symbol (a) in the figure corresponds to ~ in the circuit symbol diagram,
Similarly, symbol (b) corresponds to and symbol (c) corresponds to.

In this figure, the section in the direction in which the voltage is induced in the coil by the law of electromagnetism with respect to the induced magnetic flux that enters from the outside,
In other words, in a cross section perpendicular to the lamination direction of the coil conductor, for the magnetic member portion constituting the main magnetic circuit,
The area of the inner portion is smaller than the area of the outer portion of the coil conductor by the coil conductor.

FIG. 5 shows a model diagram of the manufacturing process of the laminated inductance element (only one-turn lamination process). This figure shows the concept of forming a laminated coil, and details of the manufacturing method are disclosed in JP-A-64-47010 and JP-A-1-198003.

The Ni-Cu-Zn-based magnetic ferrite material has a relative magnetic permeability of about 200, and the conductor used is an Ag-Pd-based material. As 50
The distance between the conductors is about 50 μm or more due to the capacitance between the coils. Although not shown in FIG. 5, a primary coil (a) and secondary coils (b) and (c) are provided between the coils by disposing a member close to a nonmagnetic material having a relative permeability of about 1. 0.97, the coupling coefficient indicating the coupling state between
The external dimensions of the laminated inductance element which can be set to 0 or more and which can make the capacitance value between the primary coil (a) and the secondary coils (b) and (c) 14 pF or less are approximately It is 5 × 5 × 2.5 mm. In this case, the number of turns of the primary coil is 6 turns, 8 μH, the step-up ratio is 2, or the number of turns of the primary coil is 10 turns, 22 μH, the step-up ratio is about 1.5, and both have intermediate taps. ing.

In FIG. 4, the conductors for the coil terminals and for the leads for establishing the electrical connection between the coils are omitted. If the relative magnetic permeability of the magnetic ferrite material is further increased, the inductance per turn can be increased, and the element can be further miniaturized.

6 (a) and 6 (b) show the transmission characteristics of the step-up transformer using the multilayer inductance element according to the present invention in comparison with the conventional toroidal coil type. The symbol L ₁ is the primary inductance in FIG, K is a primary coil 2
The coupling coefficient between the secondary coils, and Cs represents the capacitance value between the primary coil and the secondary coil.

In FIG. 9A, it can be seen that the transmission level is proportional to the value of K if Cs is approximately the same, and that the transmission level is improved when Cs becomes 14 pF or less.

FIG. 9B shows an example in which Cs is further reduced to about 12 pF, and that when Cs is 14 pF or less but K is 0.97 or less, the characteristics in a high frequency band are degraded.

FIG. 6 (c) shows the amount of leakage of the erase signal with respect to the main signal in a certain channel when the step-up transformer according to the present invention is used. FIG. 6 (d) shows the induced noise level at the output of a certain channel when the rotating cylinder is left in a strong electric field.
It can be seen from each of the figures that there is an effect of suppressing noise.

[Effects of the Invention] According to the present invention, the following effects can be expected.

(1) The function of the step-up transformer amplifies the noise that enters this part against electromagnetic induction noise from the outside of the rotating cylinder, so the outer periphery of the step-up transformer is magnetically shielded. By doing so, it has a strong suppressing power against the intrusion of the noise.

(2) Especially when the erasing head is mounted in the rotating drum,
Since the erasing circuit and another signal circuit to which the step-up transformer is connected are close to each other, the outer periphery of the step-up transformer is magnetically shielded. It also has a strong restraining force.

(3) Since the step-up transformer is constituted by the laminated inductance element, it is not necessary to magnetically shield the outer periphery of the step-up transformer with another member.

(4) By forming the step-up transformer with the laminated inductance element, the coil can be formed by the printing technique, so that the number of man-hours can be significantly reduced. Further, the size can be reduced in combination with the item (3).

(5) The coupling coefficient indicating the coupling state between the primary coil and the secondary coil in the performance of the step-up transformer should be 0.970 or more, and the capacitance value between the primary coil and the secondary coil should be 14 pF or less. Thereby, the transmission characteristics can be made practically acceptable.

(6) If the magnetic circuit is made of a material having a higher relative magnetic permeability, the number of electric circuit elements arranged in the rotating drum increases due to the downsizing of the step-up transformer more than the above. Functionalization is possible, and it is possible to mount an amplifier circuit on a small-diameter drum, which has been impossible until now. .

For example, the outer diameter of a rotary drum according to the VHS standard is φ62 mm, and the configuration shown in FIGS. 1 and 10 allows the amplifier to be mounted somehow inside the rotary drum as in this example. Since it is necessary to simply double the number of heads in order to achieve the same function, it can be presumed that a rotary drum having an outer diameter of φ41.3 mm cannot be realized by slightly reducing the function. Even if elements other than the step-up transformer are integrated and miniaturized by the current semiconductor technology, it becomes impossible to mount an amplifier circuit if the step-up transformer has the conventional size described above. However, if the magnetic circuit is made of a material having a higher relative magnetic permeability as described above, a step-up transformer of 3.5 × 3.5
It is possible to reduce the size to × 3.5 mm or less, which makes it impossible to mount an amplifier circuit.

[Brief description of the drawings]

FIG. 1 (a) is a sectional view of a main part of an embodiment of a rotary cylinder of a rotary magnetic head device according to the present invention, FIG. 1 (b) is a plan view thereof, and FIG. 1 (c) is a perspective view thereof. It is. FIG. 2 is a perspective view showing a step-up transformer according to an embodiment of the present invention. FIG. 2 (a) shows a step-up transformer in which a toroidal coil is provided on the outer periphery of a ring-shaped core. (B) shows a case where the entire circumference is surrounded by a shield member made of a magnetic material except for (a). Another embodiment is shown. FIG. 3 is a perspective view showing the appearance of one embodiment of the step-up transformer using the multilayer inductance element of the present invention. FIG. 4 is a cross-sectional view of a main part of a step-up transformer using the multilayer inductance element of the present invention shown in FIG. 3, wherein (a) shows a primary coil conductor between secondary coil conductors. FIG. 3B shows an example in which the primary coil conductors are evenly arranged between the secondary coil conductors. FIG. 5 shows a model diagram of the manufacturing process of the multilayer inductance element (only one-turn lamination process). 6 (a) and 6 (b) show the transmission characteristics of the step-up transformer using the multilayer inductance element according to the present invention.
FIG. 6 (c) is a diagram showing a comparison with a conventional toroidal coil type, and FIG. 6 (c) is a diagram showing a leakage amount of an erasure signal with respect to a main signal in a certain channel when a step-up transformer according to the present invention is used. FIG. 6 (d) is a diagram showing the induced noise level at the output of a certain channel when the rotating cylinder is left in a strong electric field. FIG. 7 (a) is a sectional view of an essential part of an embodiment of a rotary cylinder using a toroidal coil type step-up transformer which is a conventional rotary magnetic head device, and FIG. 7 (b) is a plan view thereof. FIG. 7 (c) is a perspective view thereof. FIG. 8 is an external perspective view showing a form of a conventional step-up transformer of a toroidal coil type. FIG. 9 is a sectional view of a main part of a rotary drum showing an arrangement of a magnetic head of a rotary magnetic head device according to the present invention. FIG. 10 is a block diagram showing the electrical connection of the rotary magnetic head device according to the present invention. DESCRIPTION OF SYMBOLS 1 ... Magnetic head, 1 '... Head base, 2 ... Rotary drum, 2' ... Fixed drum, 3 ... Relay board (rotor side), 4 ... Rotor core, 5 ... Rotating shaft, 6 ... Relay plate (stator side), 50 ... Drive motor, 6 '... Relay plug 7 ... Slip ring, 8 ... Stator core, 71 ... Relay lead wire, 9 ... Slip ring brush, 10 ... Magnetic Tape, 9 ': Relay plug for slip ring, 12: Ball bearing, 13: Disk, 31, 32: Pin terminal for relay, 33, 34: Amplifier circuit board, 341: Step-up transformer, 342 …… Recording integrated circuit, 343 …… Reading integrated circuit, 3410 …… Ring core, 3411 …… Coil, 3412… Terminal resin base material, 3413… Terminal 3419… Shield case, 3410 ′… ... Magnetic member for magnetic circuit, 3414 ... Nonmagnetic layer, 3411 '... Coil conductor

Continued on the front page (72) Inventor Nobuo Manabe 1410 Inada, Kataida, Ibaraki Pref.Hitachi, Ltd.Tokai Plant (72) Inventor Hiroyoshi Kawai 1410, Inada, Katsuta, Ibaraki Pref.Hitachi, Ltd. Inside the factory (56) References JP-A-60-106020 (JP, A) JP-A-64-47010 (JP, A) JP-A-55-37213 (JP, U) JP-A-57-198726 (JP, U) (58) Fields surveyed (Int.Cl. ⁷ , DB name) G11B 5/02

Claims (2)

(57) [Claims] 1. A rotating drum having a plurality of magnetic heads mounted on a rotating drum rotatably inserted and supported on an axis of the stationary drum via a mounting member, and having a plurality of magnetic heads. A rotor core attached to the rotating drum, a stator core attached to the fixed drum, and a rotating transformer for transmitting and receiving signals by disposing the cores facing each other with a small gap therebetween, connected to the rotating transformer; A rotary amplifier in which a reproducing amplifier circuit for amplifying a signal from the magnetic head and a recording amplifier circuit for amplifying a recording signal are built in a rotating drum, and a step-up transformer is connected between the amplifier circuit and the magnetic head. In the magnetic head device, the step-up transformer includes a laminated inductance element in which a main coil conductor is laminated and embedded in a magnetic member. The laminated inductance element has an area of the magnetic member portion surrounded by the coil conductor in a cross section perpendicular to the lamination direction of the coil conductor, for the magnetic member portion constituting the main magnetic circuit. It was configured to be smaller than the area of the magnetic member portion outside the coil conductor,
A rotary magnetic head device characterized by the above-mentioned. 2. The step-up transformer has a coupling coefficient between a primary coil and a secondary coil of 0.970 or more,
And the capacitance between the primary coil and the secondary coil is 14 pF
2. The rotary magnetic head device according to claim 1, wherein: