JPH07244802A - Magnetic recording / reproducing device - Google Patents

Abstract

PURPOSE:To narrow the gap between a compound magnetic head and a magnetic recording medium. CONSTITUTION:An MR compound head 34 consisting of an induction-type head 37 for recording and an MR head 38 for reproduction and a recording/ reproduction circuit 33 are connected by a transmission line 35 consisting of two lead wires L1 and L2 shared by the induction-type head 37 for recording and the ME head 38 for reproduction to reduce stiffness. A switch control circuit 39 and a switch part 40 provided at the MR compound head 34 switch the connection state to both of them. Also, a resistance change detection circuit 30 for the MR compound head 34 is laid out on the MR compound head 34. Both recording and reproduction signals are transmitted while they are superposed on current change and the switch control circuit 39 is operated by the change in potential difference between two lead wires L1 and L2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording / reproducing technique, and more particularly, to a recording induction type head for recording information on a magnetic recording medium and a reproducing MR head utilizing a magnetoresistive effect for reproducing information. The present invention relates to a technology effectively applied to a magnetic recording / reproducing apparatus using a recording / reproducing separated type composite magnetic head.

[0002]

2. Description of the Related Art A recording / reproducing separated magnetic recording / reproducing system is used in which information is reproduced by a magnetoresistive reproducing head (hereinafter referred to as an MR head) from a recording medium in which information is recorded by an inductive head in the form of magnetization inversion. It's being done. For this recording / reproducing system, a composite head in which the recording head and the reproducing head described above are integrated is used. As described above, since the composite head has a head for recording and reproducing, as shown in FIG. 9, the number of lead wires from the recording / reproducing circuit system to the composite head is different from the conventional one. 2 for each recording signal and 2 for reproduction signal for a total of 4
It was structured as a book.

On the other hand, as one of means for increasing the recording density of a magnetic disk device, a method of narrowing the flying height of a magnetic head is adopted. In order to reduce the flying height, it is necessary to reduce the size of the slider on which the composite magnetic head is mounted so that the slider can easily follow the irregularities on the medium surface. However, when the slider size is reduced, the followability is affected even if a weak external force is applied. As a cause of this weak external force, the rigidity of the lead wire has been a problem.

[0004]

As one of the measures for reducing the rigidity of the lead wire, the wire diameter is made thin. However, since the number of lead wires is as large as four for each composite magnetic head, the effect of reducing the external force is small. Therefore, it is conceivable to reduce the number of lead wires, but the reduction of the number of lead wires connecting the composite magnetic head and the recording / reproducing circuit system has not been conventionally considered.

As a similar technique related to the line number reduction method, for example, as shown in FIG. 10, a transmission line from a recording / reproducing circuit 9 (RW-IC) to a signal processing circuit at a subsequent stage is used as a recording system. The transmission line 45 (FPC (2)) having two lines is used for each of the reproduction system and the reproduction system to share the transmission line for the recording signal and the reproduction signal, and the MR composite head 12 uses the transmission line 44 (FPC for four lines). A configuration in which it is connected to the recording / reproducing circuit 9 via (3) is conceivable.

That is, in FIG. 10, in the RW-IC 9 operated by the RW-IC power source 47A, the control unit 1
One of the MR composite heads 12 is selected by the head selection signal 41A from the No. 7 head. Further, the recording / reproducing control signal 41 selects recording or reproducing. When the recording / reproducing control signal 41 means the recording state, the recording signal 43 from the recording circuit 7 is output to the recording inductive head 37 of the target composite head by the electric power supplied from the recording current source 46.

On the other hand, in the case of reproduction, the head selection signal 41A is issued from the control unit 17 and the MR composite head 12 corresponding to it is selected. Further, if the recording / reproducing control signal 41 means the reproducing state, the signal from the reproducing MR head 38 performing the reproducing operation using the bias current of the MR sense current source 47 is reproduced by the reproducing signal 42 via the RW-IC 9. Is output to the reproduction circuit 13.

According to the conventional idea, the RW-IC 9 is arranged on the MR composite head 12 in order to reduce the number of lead wires provided along a supporting member such as a head arm for supporting the composite head. It will be. But R
The W-IC power supply 48 and an additional signal line such as a recording / reproducing mode switching signal are required, and eventually the number of lines increases. If the RW-IC 9 is mounted on a smaller slider, the recording-side amplifier circuit of the RW-IC 9 consumes a large amount of power, and thus the slider may be deformed due to heat generation of the IC.

An object of the present invention is to provide a magnetic recording / reproducing technique capable of reducing the rigidity of a support structure for supporting a composite magnetic head on an actuator to further reduce the flying gap of the composite magnetic head with respect to a magnetic recording medium. To provide.

Another object of the present invention is to alleviate or eliminate the band limitation in the transmission line which is the information transmission path between the composite magnetic head and the recording / reproducing circuit, thereby realizing higher speed data transfer. It is to provide a possible magnetic recording / reproducing technology.

[0011]

A magnetic recording / reproducing apparatus of the present invention includes a recording / reproducing circuit when a composite magnetic head is composed of, for example, a reproducing inductive head and a reproducing MR head using a magnetoresistive effect element. , (1) First stage of reproduction amplifier circuit (MR resistance change detection circuit) (2) Divide into two parts, recording side and rear stage part of reproduction amplifier circuit. Then, the first-stage resistance change detection circuit on the reproducing side of (1) is mounted on the MR composite magnetic head,
The part (2) is attached to the carriage or actuator side.

The first and second transmission lines are shared by the reproducing magnetic head and the recording magnetic head forming the composite magnetic head by the current signal transmission method of the recording signal and the reproducing signal.

Since the first-stage resistance change detection circuit on the reproducing side is mounted on the composite magnetic head, the power supply line of the circuit is also shared with the first and second transmission lines. In this case, the circuit power supply current is always a constant value, and the signal current changes, so separation is possible. Therefore, it is possible to share the line between the signal and the power supply.

Further, switching means is provided for switching between the recording and reproducing paths so that the recording current does not leak to the reproducing head side and the reproduced signal does not leak to the recording side. The switching means can be composed of a switch control circuit that operates by a potential difference between the first and second transmission lines.

Also, the two first and second transmission lines are
The composite magnetic head may also function as a support member that supports the actuator.

[0016]

In the magnetic recording / reproducing apparatus of the present invention, by reducing the number of transmission lines from the conventional four to two of the first and second transmission lines, it is possible to reduce the influence of the external force on the levitation characteristics.
It is possible to further reduce the flying gap with respect to the magnetic recording medium. This makes it possible to improve the recording density by lowering the flying height of the composite magnetic head.

Further, by mounting the resistance change detection circuit at the first stage on the reproduction signal side in the vicinity of the composite magnetic head, the reproduction signal is transmitted as in the case where the resistance change detection circuit is arranged at a position separated from the composite magnetic head. The first and second transmission lines can be used as channels for high-speed data transfer without being subject to band limitation by the route.

[0018]

Embodiments of the present invention will now be described in detail with reference to the drawings.

1 and 2 are conceptual diagrams showing an example of the configuration of a magnetic recording / reproducing apparatus according to an embodiment of the present invention.

The magnetic recording / reproducing apparatus of the present invention uses a magnetoresistive head (MR head) such as a magnetic disk device, a magnetic tape device, a floppy disk device, a digital VTR device or a magnetic card reading device to output signals. Although it can be applied to all reproducing devices, in the present embodiment, as an example, a case of being applied to a magnetic disk device will be described.

First, an example of the overall structure of the magnetic disk device will be described with reference to FIG. Magnetic disk device 10
Is a storage device that receives and stores information from the higher-level machine 19 or outputs corresponding information to the higher-level machine 19 in response to a request for information submission. The configuration is such that an interface circuit 18 for inputting / outputting information to / from the host computer 19 and information input through the interface circuit 18 are stored in the magnetic recording medium
It includes a modulation / demodulation circuit 8 for performing a modulation operation for converting into a code for recording to and a demodulation operation for demodulating a code reproduced from the magnetic recording medium 11 into information that can be understood by the host computer 19. Further, the code recorded on the magnetic recording medium 11 is subjected to recording correction and the like by the recording circuit 7, and the recording / reproducing circuit 33.
(RW-IC) converts into a current waveform signal (NRZI) for recording. The recording current waveform signal is supplied to the MR composite head 34.

The MR composite head 34 is used for the magnetic recording medium 11.
And a magnetoresistive head (reproducing MR head 38) for reproducing the magnetization information of the magnetic recording medium 11 by using the magnetoresistive effect. There is. The recording current waveform signal described above is applied to the magnetic recording medium 11 by the recording inductive head 37.
Recording is performed in the form of magnetization reversal.

Information is reproduced by the reproducing MR head 38 in the MR composite head 34 and the recording / reproducing circuit 33.
The signal is amplified at. Then, the reproduction circuit 13 performs waveform shaping and discrimination to obtain the signs of "1" and "0". The digital code of the discrimination result is converted into information in the modulation / demodulation circuit 8.

One or a plurality of magnetic recording media 11 for storing information are incorporated, and a motor 20 for rotating the spindle 20a via a spindle 20a in which the magnetic recording media 11 are stacked in a coaxial and parallel posture.
Supported by. At least one MR composite head 34 is arranged on each surface of the magnetic recording medium 11.

In order to write information to a certain track position on the magnetic recording medium 11, a plurality of MR composite heads 34 are mechanically supported in the gaps of the stack of the magnetic recording medium 11 via the arms 14a, and further MR to the target track position. The actuator 14 for feeding the composite head 34, and the voice coil motor 15 for driving the actuator 14.
(VCM), and the MR composite head 34 takes in servo information, and the positioning control 16 for performing control to move to a predetermined radial position constitutes a servo system.

Each of the above-mentioned constituent elements of the magnetic disk device 10 is controlled under the control of the control unit 17.

In the case of the present embodiment, as illustrated in FIG. 1, a transmission line 35 consisting of two lead wires L1 and L2 is provided between the MR composite head 12 and the recording / reproducing circuit 9.
(FPC (1)) is used for connection. The transmission line 35 (FPC (1)) has, for example, a structure in which two lead wires L1 and L2 are formed by a conductor pattern inside a flexible insulating resin.
In the case of this embodiment, the transmission line 35 is composed of a plurality of MRs.
Each of the composite heads 34 has a corresponding actuator 14
It also functions as a support member for supporting the arm 14a.

In the case of this embodiment, as shown in FIG. 1, the recording / reproducing circuit 33 (RW-IC) is replaced with the resistance change detecting circuit 30 (R-IC) in the first stage on the reproducing side, and the main amplifying circuit on the reproducing side. And a reproduction signal selection circuit 31 (head selection circuit) and a recording side current waveform conversion circuit 32 (W-IC). The recording / reproducing circuit 33 has a reproducing signal selecting circuit 31, a current waveform converting circuit 32 (W-IC), and a transmission line 35 (FPC (FPC ( 1)), a switch section for selecting whether to send a recording signal or receive a reproduction signal and a switch control section 36A (SW) for controlling the switch.
A switch circuit 36 configured by control) is included.

The MR composite head 34 includes a recording inductive head 37 for recording and a reproducing MR head 38 for reproducing, and a recording signal is sent as a signal of the transmission line 35 (FPC (1)). Switch control circuit 39 (SW control) for controlling the head connected to the transmission path, the switch section 40 for actual connection, and the resistance change of the reproducing MR head 38. Resistance change detection circuit 30 in the first stage on the reproducing side for converting the current into a current change
(R-IC) is installed.

Next, an embodiment of a method of manufacturing the MR composite head 34 of this embodiment will be described with reference to FIG.

In the conventional manufacturing method, an MR head and an induction type head are formed in a laminated structure on a wafer by using a substrate whose slider length corresponds to the thickness of the wafer, and then the slider is cut out and finally a sliding surface is formed. It is common to perform processing.

In the case of this embodiment, in the conventional manufacturing method, before forming the reproducing MR head 38 on the wafer,
A switch section 40 and a switch control circuit 39 are formed, and a resistance change detection circuit 30 (R-IC), a terminal 37a of the recording induction type head 37, a switch control circuit 39,
The input terminal 40a for the switch unit 40 is formed. After that, a reproducing MR head 38 and a recording induction type head 37 are formed and cut out as sliders. Further, the sliding surface of each slider is subjected to negative pressure slider processing and polishing, for example, in which grooves and protrusions are formed in parallel with the traveling direction relative to the magnetic recording medium 11. Then, a protective film is formed on the sliding surface to complete the process.

Next, the recording side current waveform conversion circuit 32 (W-
An embodiment of the output stage of the IC will be described with reference to FIGS.

The recording signal 43 whose recording timing has been corrected in the recording circuit 7 is converted into the current waveform conversion circuit 32 (W-I).
C), and the recording signal 43 is converted into recording data 49. At the output stage, the recording data 49 is input as a differential signal to the bases of the transistors Q71 and Q72. The base of the transistor Q73 is connected to the emitter of the transistor Q71, and the transistor Q72
Is connected to the base of the transistor Q74.
The transistor Q73 and the transistor Q74 are the current sources I
It is a current switch for the current Iw of the WG4. Further, the emitter of the transistor Q71 is connected to the base of the transistor Q75 via the level shift circuit 65, and the emitter of the transistor Q72 is connected to the base of the transistor Q76 via the level shift circuit 66. The transistor Q75 and the transistor Q76 are current switches for the current Iw of the current source IWG2. Where the current source IWG
Reference numeral 4 causes the same current Iw to flow from the current source IWG2 via the current copy circuit 50.

For convenience of explanation, the P side of the recorded data 49 is "
It is assumed that the "high" level and the N side are "low" levels.In this case, the emitter of the transistor Q71 is Q.
The level is higher than that of the emitter of 72. Therefore, the transistors Q74 and Q75 of the two current switch circuits connected to the transistors Q71 and Q72 are activated.

The recording inductive head 37 is connected between the collectors of the transistors Q73 and Q74. Since the transistor Q75 is in the active state based on the assumption of the current input level, the current Iw flows through the recording induction type head 37 in the direction from the transistor Q74 to Q75. Also recorded data 4
When the input level of 9 is inverted, from the above level relation,
The recording current of the recording induction type head 37 is reversed.

Next, an embodiment of a method of connecting the resistance change detection circuit 30 (R-IC) on the MR composite head 34 and the input stage of the reproduction signal selection circuit 31 will be described with reference to FIG.

In the configuration of this circuit system, the reproduction signal selection circuit 3
The voltage V1 is applied to the base of the transistor Q83 in the circuit 1. As a result, the emitter voltage of the transistor Q83 becomes (V1-Vbe [Q83]). On the other hand, the voltage V is applied to the base of the transistor Q84.
Give 2. As a result, the emitter voltage of the transistor Q84 becomes (V2 + Vbe [Q84]). Here, the relationship between the voltages V1 and V2 is (V1-V2)> V. The potential difference V is the sum of the base-emitter voltage of the transistor described below and the bias voltage to the reproducing MR head 38.

The emitter of the transistor Q83 has an MR
Resistance change detection circuit 30 in the first stage on the reproducing side of the composite head 34
The collector and base of the (R-IC) transistor Q81 are connected. A bias resistor 51 is connected between the base of the transistor Q81 and the base of Q82. A reproducing MR head 38 is connected between the emitters of the transistors Q81 and Q82. The base and collector of the transistor Q82 are connected. Further, the collector of the transistor Q82 is connected to the emitter of Q84. Transistor Q83
A resistor 52 is connected to the collector of the transistor Q84
A resistor 53 is connected to the collector of the.

The operation of this circuit system will be described below.

The output terminal 5 of the resistance change detection circuit 30 (R-IC) in the first stage on the reproduction side is formed by the transistors Q83 and Q84.
The voltage (V1−Vbe [Q83]) is applied to the output terminal 4 and (V2 + Vbe [Q84]) is applied to the other output terminal 55. When the sense current of the reproducing MR head 38 is passed as Is, the resistance change detection circuit 30 (R-I
The current Io of the output terminals 54 and 55 in C) can be expressed by the following equation.

Io = Is + (V1-V2-2Vbe) / R where Vbe: base-emitter voltage of the transistor Vbe = Vbe (Q83) = Vbe (Q84) R: bias resistor 51 Further, the sense current Is is expressed by the following equation. be able to.

Is = (V1-V2-4Vbe) / Rmr where Vbe: voltage between base and emitter of transistor Vbe = Vbe (Q83) = Vbe (Q84) = Vbe (Q81) = Vbe (Q82) Rmr: MR head for reproduction DC resistance of 38 From the above equation, the sense current Is is determined by the transistors Q83 and Q8.
4 is a function of the base potential difference. Therefore, the sense current can be optimized by adjusting (V1-V2).

Now, when the reproducing MR head 38 detects the magnetic field from the magnetic recording medium 11, the resistance of the reproducing MR head 38 changes by δR. But transistors Q81 and Q8
Since the voltage between the two emitters does not change, Q81, Q82
Of the emitter current, that is, the collector current of
Only changes.

Δi = -δR (V1-V2-4Vbe) /
{(Rmr + δR) × Rmr} Therefore, the transistors Q83 and Q84 convert the signal current δi into the signal voltage δv by the resistors 52 and 53 connected to the collectors as shown in the following equation.

Δv = δi × R Next, an example of the overall operation of this embodiment will be described with reference to FIGS. 1 and 6.

First, there are roughly classified recording and reproducing operations. The recording / reproduction control signal 41 may be used as the mode signal for identifying the two. In FIG. 6, as an example, the recording / reproduction control signal 41 corresponds to the recording mode when it is at the “high” level and corresponds to the reproduction mode when it is at the “low” level.
In the present embodiment, the recording / reproducing control signal 41 causes the switch control section 36A of the switch circuit 36 of the recording / reproducing circuit 33.
To control. The switch control unit 36A connects the switch in the switch circuit 36 to the recording inductive head 37 side or the reproducing MR head 38 side.

Now, consider the case where the recording side (A1-A2 terminals) is connected. At this time, since the recording information is output from the W-IC 32, the waveform as shown in the recording column of the A1-A2 row in FIG. 6 is output. At this time, since the switch is on the recording side, the transmission line 35 (FPC
(1)) C1-C of each of the two lead wires L1 and L2
The waveform shown in FIG. 6 appears at the two terminals.

On the other hand, consider the case of connection to the reproducing side (B1-B2 terminals). At this time, as described with reference to FIG. 5, a potential difference is applied between the two lead wires L1 and L2 of the transmission line 35 (FPC (1)). Therefore, B1 in FIG.
A potential difference is generated between the terminals as in the case of the reproducing column on the -B2 row. By switching the switch between recording and reproduction as described above, the two lead lines L1 and L2 of the transmission line 35 (FPC (1)) are set to the time as shown in the column of the line C1-C2 in FIG. By sharing, it can be commonly used as a signal transmission path for recording and reproduction.

Next, one embodiment of the switch control circuit 39 and the switch section 40 in the MR composite head 34 will be described with reference to FIGS. 1, 7 and 8.

In FIG. 7, the collector and the base of the transistor Q91 are one lead wire L1 of the transmission line 35.
Is connected to the other lead wire L2 through an integrating circuit 70 including a resistor 56 and a capacitor 58. The transistor Q92 has a collector connected to the lead wire L1 side through the load resistor 57, an emitter connected to the lead wire L2 side, and a base connected between the resistor 56 and the capacitor 58 forming the integrating circuit 70. There is. The Schmitt trigger inverter 59 is connected to the collector side of the transistor Q92, and the switch control circuit 3
The switch unit 40 is driven as the output of 9.

In the case of the present embodiment, the following states are used as the SW control signal for switching the switch section 40 in the MR composite head 34. That is, during reproduction, the lead wire L1
Note that a potential difference is applied between the two lines L and L2, and that no DC voltage is generated between the two lines during recording. However, since the recording inductive head 37 has an inductance, when a rectangular current waveform is applied, a flyback voltage waveform 62 as shown in the recording section of FIG. 8 appears. Therefore, as shown in FIG. 7, the switch control circuit 39 is provided with an integrator circuit 70 (composed of a resistor 56 and a capacitor 58) for not responding to the impulsive flyback voltage waveform 62. Further, the transistor Q91 is for shutting off so as not to be affected when the recording current waveform has a reverse phase. Therefore, since the DC voltage is applied in steps during reproduction, the threshold level is exceeded after the time constant of the integrating circuit. At that time, the switch unit 40 can be switched.

The switching of the switch unit 40 is performed as follows. On the recording inductive head 37 side, a switch 60 having a B contact specification (a specification that is normally connected and is cut off when a signal is input) is used. On the reproducing MR head 38 side, a switch 61 having an A contact specification (normally cut off state and connected at the time of signal input) is used. As a result, if a voltage longer than the time constant of the integrating circuit is applied to the switch control unit 36A, a switch switching signal is output, and the two lead wires L1 and L2 are connected to the recording inductive head 37 and the reproducing MR head 38. Will switch.

However, by using this method, the switch section 40 does not switch during the time constant of the integrating circuit 70, so that the DC erased state as shown in FIG. (Region) occurs. Therefore, it is desirable to provide a reproduction buffer area and a recording buffer area as the format of the magnetic recording medium 11.

As described above, according to the magnetic recording / reproducing apparatus of this embodiment, the MR composite head 34 and the recording / reproducing circuit 33 are connected to each other by the two first and second lead wires L1 of the transmission line 35. , L2 makes it possible to
The external force applied to the MR composite head 34 due to the rigidity of the transmission line 35 can be reduced, and the variation in the attitude of the slider for flying the MR composite head 34 over the magnetic recording medium 11 is reduced, and the MR with respect to the magnetic recording medium 11 is reduced. The flying height of the composite head 34 can be further narrowed. Thereby, the recording density in the magnetic recording medium 11 can be improved.

Further, the resistance change detection circuit 30 in the first stage on the reproduction signal side is connected to the reproduction MR head 38 in the MR composite head 34.
Mounted in the vicinity of and between the first and second lead wires L
With the configuration in which 1 and L2 are not interposed, the band limitation by the first and second lead lines L1 and L2 is eliminated, and in particular, the effect that the reproduction data can be transferred at high speed is obtained. To be

The first and second lead wires L1 and L
Via the transmission line 35 constituted by
Since the composite head 34 is configured to be supported by the arm 14a of the actuator 14, extra parts such as leaf springs can be omitted, and the configuration can be simplified and the cost can be reduced.

[0058]

According to the magnetic recording / reproducing apparatus of the present invention, the rigidity of the support structure for supporting the composite magnetic head on the actuator can be reduced to further reduce the flying gap of the composite magnetic head with respect to the magnetic recording medium. You can get the effect.

Further, the effect that the band limitation on the transmission line, which is the information transmission path between the composite magnetic head and the recording / reproducing circuit, is relaxed or eliminated, and higher speed data transfer can be realized is obtained. To be

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing an example of the configuration of a magnetic recording / reproducing apparatus that is an embodiment of the present invention.

FIG. 2 is a conceptual diagram showing an example of the configuration of a magnetic recording / reproducing apparatus that is an embodiment of the present invention.

FIG. 3 is a conceptual diagram showing an example of a method of manufacturing an MR composite head that constitutes a magnetic recording / reproducing apparatus according to an embodiment of the present invention.

FIG. 4 is a circuit diagram showing an example of a configuration of a current waveform conversion circuit that constitutes a magnetic recording / reproducing apparatus according to an embodiment of the present invention.

FIG. 5 is a circuit diagram showing an example of a configuration of a reproduction signal selection circuit and a resistance change detection circuit which constitute a magnetic recording / reproduction device according to an embodiment of the present invention.

FIG. 6 is a diagram showing an example of the operation of the magnetic recording / reproducing apparatus which is an embodiment of the present invention.

FIG. 7 is a circuit diagram showing an example of a circuit configuration of an MR composite head that constitutes a magnetic recording / reproducing apparatus according to an embodiment of the present invention.

FIG. 8 is a diagram showing an example of the operation of the magnetic recording / reproducing apparatus which is an embodiment of the present invention.

FIG. 9 is a block diagram showing an example of a configuration of a conventional magnetic recording / reproducing apparatus.

FIG. 10 is a block diagram showing an example of a configuration of a conventional magnetic recording / reproducing apparatus.

[Explanation of symbols]

7 ... Recording circuit, 8 ... Modulation / demodulation circuit, 9 ... Recording / reproducing circuit, 10 ... Magnetic disk device, 11 ...
Magnetic recording medium, 12 ... MR composite head, 13 ...
Reproducing circuit, 14 ... Actuator, 14a ... Arm, 15 ... Voice coil motor, 16 ... Positioning control, 17 ... Control unit, 18 ... Interface circuit, 19 ... Higher-level machine , 20 ... Motor, 20a
... Spindle, 30 ... Resistance change detection circuit, 31
... Reproduction signal selection circuit, 32 ... Current waveform conversion circuit, 33 ... Recording / reproduction circuit, 34 ... MR composite head (composite magnetic head), 35 ... Transmission line, L1 ...
Lead wire (first transmission wire), L2 ... Lead wire (second wire)
Transmission line), 36 ... switch circuit (switching means), 36A ... switch control section (switching means),
37 ... Recording induction head, 37a ... Terminal, 3
8 ... Reproducing MR head, 39 ... Switch control circuit (switching means), 40 ... Switch section (switching means), 40a ... Input terminal, 41 ... Recording / playback control signal, 41A. ..Head selection signal, 42 ... Playback signal, 43 ... Recording signal, 44 ... Transmission line, 45 ...
..Transmission line, 46 ... Recording current source, 47 ... MR sense current source, 47A ... RW-IC power source, 48 ...
RW-IC power supply, 49 ... Record data (input), 50
... Current copy circuit, 51 ... Bias resistor, 52
... resistance, 53 ... resistance, 54 ... output terminal, 5
5 ... Output terminal, 56 ... Resistance, 57 ... Load resistance, 58 ... Capacitor, 59 ... Schmitt trigger inverter, 60 ... Switch (B contact specification),
61 ... Switch (A contact specification), 62 ... Flyback voltage waveform, 65, 66 ... Level shift circuit,
70 ... Integrator circuit, IWG1 to IWG4 ... Current source, Q71 to Q76 ... Transistor, Q81 to Q8
4 ... Transistor, Q91, Q92 ... Transistor

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Seiichi Mita 2880 Kozu, Odawara-shi, Kanagawa Stock Company Hitachi Storage Systems Division

Claims (3)

[Claims] 1. A magnetic recording medium, a recording magnetic head for recording information on the magnetic recording medium, and a composite magnetic head in which a reproducing magnetic head for reproducing the information from the magnetic recording medium are integrated, and a supporting member. An actuator, to which the composite magnetic head is fixed, for positioning the composite magnetic head with respect to the magnetic recording medium, a recording / reproducing circuit provided independently of the composite magnetic head on the actuator side, and to the support member. Two first and second transmission lines that are arranged along the same line and connect the composite magnetic head to the recording and reproducing circuit, and the first and second transmission lines for the recording magnetic head and the reproducing magnetic head. A magnetic recording / reproducing apparatus comprising: switching means for switching connection. 2. The recording magnetic head and the reproducing magnetic head each comprise a recording inductive head and a reproducing MR head using a magnetoresistive effect element, and the recording / reproducing circuit stores at least the magnetic recording medium. A current waveform conversion circuit that converts the information to be written into a current waveform of a recording signal and applies the current waveform to the recording induction head;
A resistance change detection circuit for obtaining a reproduction signal from the reproducing MR head as a change in bias current applied to the magnetoresistive effect element, applying a recording signal to the recording magnetic head, and reproducing from the reproducing magnetic head. A signal is sampled by superimposing the information on the current flowing through the first and second transmission lines, and the switching means is provided on the side of the actuator, and the first and second transmission lines are provided. To give a specific DC potential difference to the first
Switch control circuit and the composite magnetic head, and detects the specific DC potential difference given to the first and second transmission lines from the first switch control circuit to detect the first and second A second switch control circuit for switching which one of the recording magnetic head and the reproducing magnetic head the transmission line is connected to, the switching means is configured to switch between the first and second transmission lines. A third transmission line provided in parallel, a third switch control circuit provided on the actuator side and outputting a switching signal to the third transmission line, and provided on the composite magnetic head, From the third switch control circuit to the third
And a fourth switch control circuit that switches the connection between the first and second transmission lines to the recording magnetic head or the reproducing magnetic head by detecting the switching signal output to the transmission line. The magnetic recording / reproducing apparatus according to claim 1, further comprising at least one of the following second configuration. 3. A resistance change detection circuit for obtaining a reproduction signal from the reproducing MR head as a change in bias current applied to the magnetoresistive effect element is arranged on the composite magnetic head. 2. The magnetic recording / reproducing apparatus according to 2.