JPH08249613A - Compound type magnetic head - Google Patents

Abstract

PURPOSE: To improve overwrite-characteristics and to reduce the number of parts and assembly man-hour by increasing the width of an erasure head as compared with before and adopting the erase-and-write system. CONSTITUTION: A single recording/reproducing head coil and a single erasure head oil are used and the erasure head consists of cores 11A and 11B and a coil assembly 11C, thus forming an erasure gap 11D. A recording/reproducing head consists of cores 12A and 12B and a coil assembly 12C, thus forming a recording/reproducing gap 12D. Then, the head width (not gap width) of the erasure head is wider than the head width of the recording/reproducing head and the erasure head is arranged so that it precedes the recording/reproducing head when a floppy disk rotates, thus enabling the erasure head to precede the recording/reproducing head, perform erasure operation over the entire width of a track, and to completely erasure past recording.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite magnetic head, and more particularly to a composite magnetic head which is a composite of a recording / reproducing and erasing head used in a floppy disk drive or the like.

[0002]

2. Description of the Related Art In order to record / reproduce on / from a magnetic recording medium such as a floppy disk, a composite type magnetic head having a recording / reproducing head and an erasing head is used.
Along with the miniaturization of floppy disks and floppy disk drives, magnetic heads have also become smaller and have a more precise structure, but the market needs are low-priced floppy disks that satisfy sufficiently high reliability and operability.・ It is demanding to supply plenty of drive.

A magnetic head known as an ordinary bulk type head includes a ceramic slider that is in sliding contact with the recording surface of a magnetic recording medium, a gimbal spring that supports the slider on a carriage arm, and the like. A composite magnetic core having an erase gap, a recording / reproducing coil assembly and an erase coil assembly attached to the composite magnetic core, and a back core magnetically closing an open end of the magnetic core are incorporated.

In such a composite type magnetic head, the manufacturing error of the head itself causes variations in the electromagnetic conversion characteristics during recording / reproduction, which limits compatibility with other devices, and therefore the degree of precision is high. In addition, in order to manufacture easily, the number of parts is reduced, the structure is simple, and it is necessary to reduce the mass of the head itself in order to have sufficient strength against movements that follow the recording surface of the floppy disk and external impacts. There is a request.

In order to meet such various demands, various efforts have been made to improve the characteristics of the composite magnetic head and various improvements have been made in order to reduce the cost.

As a typical conventional apparatus to meet such a demand, it is disclosed in Japanese Patent Application Laid-Open No. 5-135323, and a conventional apparatus such as a combination of an erasing head and a recording / reproducing head and a simplification of the structure and assembly over the entire head is disclosed. There has been proposed an improvement plan for the composite magnetic head.

In the conventional composite magnetic head, two coils are wound around the coil assembly of the recording / reproducing head, and at the time of recording, one of the above two coils is selected by the control circuit to be energized to drive the floppy disk. A record is left by performing a magnetizing action on. The magnetizing action is such that the direction of the magnetic pole on the track of the floppy disk is NS or S
In order to have the N direction, the two coils are arranged so as to generate magnetic flux in opposite directions, and are sequentially switched according to the data to be recorded.

[0008]

As described above, the two coils cause magnetic fluxes in opposite directions to flow in the core of the recording / reproducing head. However, the magnetic poles are not instantaneously inverted for the reason described below, and are temporally changed. Inverted state is delayed.

The reason for this is explained as follows. Fig. 2 shows the state when the coil is energized or cut off. The state when energized is shown in Fig. 2A. The current flowing in the coil increases according to the time constant determined by the inductance component of the coil and the resistance component of the path. To do. Therefore, it takes T0 time to reach the set current value. The state at the time of interruption is shown in FIG. 2B, and the energy stored in the core of the head is not released instantaneously and decreases in accordance with the discharge time constant as in the case of energization, and requires T1 time. The total magnetic flux flowing in the core of the head is shown in FIG. 2C. In FIG. 2C, the magnetic flux flowing in the head is plotted on the vertical axis.
When the energization of the coil is switched at t = 0 and the magnetic flux is switched from the negative direction to the positive direction, the direction of the magnetic flux until immediately before is negative, but the direction is changed as shown in FIG. 2A and FIG. 2B. It gradually rises due to arithmetic interaction, and reaches a positive set value after passing 0. Since T2 time is required during this period, it changes at a delayed timing unlike the switching signal of the control circuit. This period is called the transition period, and the transition state is recorded on the floppy disk as it is, but the current value during this transition period is low, and therefore the magnetic force is insufficient, so there is a possibility that the previous recording may not be completely erased. I have a secret.

Although the overwrite characteristic is an evaluation item indicating the performance of the floppy disk drive device, as described above, when the previous record cannot be completely erased, the overwrite characteristic value is lowered and the reliability is deteriorated. It is one of the causes.

An object of the present invention is to solve the above-mentioned drawbacks, improve the overwrite characteristics of a composite type magnetic head, and pave the way for future large capacity and high density, and at the same time reduce the cost of a floppy disk. To provide a drive.

[0012]

In order to achieve the above object, the gist of the present invention is to provide a composite magnetic head comprising a recording / reproducing head and an erasing head, each of which has a coil assembly wound around each head. This is due to the placement of individual coils.

In order to ensure the erasing operation, the erasing head has a wide head structure for erasing over the entire width of the track, whereas the conventional erasing head erases only on both sides of the track. Since the composite magnetic head according to the present invention employs the erasing / writing method as will be described later, the erasing head is arranged so as to come into contact with the floppy disk before the recording / reproducing head.

Further, each coil wound around the recording / reproducing head and the erasing head is connected with one terminal as a common terminal and is connected to the control circuit by a total of three connecting wires.

[0015]

Next, the operation will be described. In the composite magnetic head according to the present invention, in order to ensure the erasing operation, the erasing head precedes the recording / reproducing head instead of the overwrite method (direct overwriting) used in the conventional floppy disk drive. Erase operation over the entire track width,
Completely erase past records.

For this reason, the erasing head is energized for all the time during recording, and switching is not performed. Thus, the recording head comes into contact with the completely erased floppy disk surface. Further, since the erasing operation by the erasing head has a certain direction of the magnetic pole, if this direction is, for example, the NS direction, and this direction corresponds to the magnetization direction when the write signal is "0", the recording head By energizing only the portion corresponding to "1" of the write signal and magnetizing in the SN direction, the same recording as in the conventional case is possible.

[0017]

Embodiments will be described below with reference to the drawings. FIG. 1 is a perspective view modeling a structure of a composite magnetic head according to the present invention. The left side of the drawing is a core 11A constituting an erasing head.
And 11B and the coil assembly 11C to form the erase gap 11D. On the other hand, the right side of the drawing is composed of cores 12A and 12B and a coil assembly 12C which form a recording / reproducing head, and forms a recording / reproducing gap 12D. The erasing head and the recording / reproducing head are combined with an adhesive 14 represented by glass. In the case of this embodiment,
In order to complete the head, other parts are required in addition to the parts shown in the figure, but they are omitted.

An important point in FIG. 1 is that the head width (not the so-called gap width) of the erasing head is wider than the head width of the recording / reproducing head. This is for erasing the entire track width as described above. The recording width of data is performed by a recording / reproducing head having a narrow width as in the conventional case. In FIG. 1, an arrow is drawn from left to right, which indicates that the floppy disk is rotating in the direction of the arrow. This means that when viewed from a point on the floppy disk, the erasing head is the recording / reproducing head. It means to be ahead.

FIG. 3 is a connection diagram of the composite magnetic head according to the present invention and a control circuit. The control circuit is shown only in the part that is the subject matter of the present invention. One terminal of the erasing head coil 11C of the composite magnetic head and one terminal of the recording / reproducing head coil 12C are connected as a common terminal to form a flexible circuit board (hereinafter referred to as FPC). ) 20 is connected to the control circuit 30. Inside the control circuit 30, electronic switches 31, 32,
33 is provided, the electronic switch 31 is provided between the positive power source and the common terminal of the coil, and the electronic switches 32 and 33 are provided between the other terminal of the coil and the ground. The switches are controlled to control recording and reproduction. The amplifier 34 is connected in parallel with the coil 12C of the recording / reproducing head.

FIG. 4 shows the electronic switches 31 to 31 shown in FIG.
33 is a timing chart of control signals S1, S2, and S3 of 33, in which the left half of the drawing depicts a control signal for recording and the right half depicts a control signal for reproduction. In the present embodiment, the switches and control signals depicted in FIGS. 3 and 4 are turned on when the control signal is “1” and turned off when the control signal is “0” for convenience. The data “0” and “1” in the bottom row shown in FIG. 4 show an example of a data array when the MFM modulation method is adopted. When the data is “1”, one set is included in one section. It has a combination of 1 and 0, and when the data is "0", it is based on the rule that the immediately preceding state is inverted and the inverted state is held for one section.

Next, the operation at the time of writing will be described. When writing, the electronic switch 31 provided in the control circuit 10 is turned on, and at the same time, when the write signal is "0", the electronic switch 33 is also turned on. In FIG. 4, the control signal S correspondingly corresponds to this.
1 and S3 are turned on (because the first data shown in FIG. 4 is "0"). As a result, a current is supplied to the erase coil 11C, and the erase operation is started. Therefore, the previous record left on the surface of the floppy disk contacting the head is erased, and at the same time, the write signal "0" is pre-recorded continuously.

When the write signal "1" is recorded, if the control signal S2 is raised in response to the write signal and the electronic switch 32 is turned on, the recording / reproducing coil 12C.
Is also energized, and the recording operation of the write signal "1" is started. The "1" of the write signal is recorded in such a manner as to interrupt the portion recorded with "0".

On the other hand, the operation during reproduction is as follows. In the case of reproduction, the induced voltage generated in the recording / reproducing coil 12C is guided to the amplifier 34, and the data is reproduced after being amplified. At this time, it is desirable to disconnect both coils from the power supply line, so all the electronic switches 31, 32, 33
It is achieved by turning off. This is as depicted on the right side of FIG.

[0024]

As described above, according to the present invention, since the write signals "0" and "1" are recorded by different heads during recording, one coil of the recording / reproducing head and one coil of the erasing head are both recorded. Since it is sufficient to use a single piece and the currents always flow in the same direction, there is no inversion of the magnetic flux flowing in the magnetic core and no interaction due to inversion, and the transition period is shorter than in the conventional method.

The overwrite characteristic at the time of reproduction is greatly improved by completely erasing the previous recording and then writing this time and shortening the transition period.
As a result, the unstable state at the time of reproduction, which often occurs in the past, is avoided, and highly reliable recording / reproduction is possible.

At the same time, the great effect brought about by the composite magnetic head of the present invention is that the number of coils used in the recording / reproducing head is two as in the conventional case. . The number of wires of the FPC for connecting the head and the control circuit was conventionally 6 to 5, but in the present embodiment, it is 3
Since it is sufficient to use a book, it is possible to greatly reduce the used area, and the cost reduction effect is great. Since the structure of the erase head can be simplified, the process reduction effect and the yield improvement. The effect of reducing the number of assembly steps for the entire head. As a result, a direct cost reduction effect and an indirect cost reduction effect by improving the yield can be obtained.

In addition, in the magnetic head according to the present invention, as described above, the effect of shortening the transition period at the time of recording is not only the improvement of the reliability represented by the overwrite characteristic but also the error at the time of data reproduction. It has the potential to reduce the rate and increase the density and capacity required for future floppy disk drives.

[Brief description of drawings]

FIG. 1 is a perspective view of an example in which a composite magnetic head according to the present invention is modeled.

FIG. 2 is a diagram illustrating a current and a magnetic flux flowing in a coil.

FIG. 3 is a connection diagram of a composite magnetic head according to the present invention and a control circuit.

FIG. 4 is a time chart diagram of signals for controlling electronic switches.

[Explanation of symbols]

 11A Erase head core 11B Erase head core 11C Erase head coil assembly 11D Erase head gap 12A Recording / reproducing head core 12B Recording / reproducing head core 12C Recording / reproducing head coil assembly 12D Recording / reproducing head gap 14 Adhesive 20 Flexible circuit board 30 Control circuit 31 Electronic switch 32 Electronic switch 32 33 Electronic Switch 34 Amplifier

Claims (4)

[Claims] 1. A composite magnetic head comprising a recording / reproducing head and an erasing head, and a coil assembly wound around each of the recording / reproducing head and the erasing head, each coil assembly having only one coil. A composite type magnetic head. 2. A composite magnetic head, wherein the erase head erases over the entire track width. 3. A composite magnetic head, wherein the erasing head is arranged so as to precede the recording / reproducing head with respect to the rotation of a floppy disk. 4. The composite magnetic head according to claim 1, wherein each coil of the composite magnetic head is connected using one terminal as a common terminal and is connected to a control circuit by three connecting wires.