JPH0737204A - Recording / reproducing circuit for magnetic head - Google Patents

Abstract

(57) [Summary] [Construction] In the recording mode, the selector switch 35 is switched and connected to the selected terminal a side to supply the recording current from the recording current source 25 to the driver 32, and in the reproducing mode, the selector switch 35 is selected. The bias current from the bias current source 26 is supplied to the driver 32 by being switched and connected to the terminal b side. The driver 32 supplies a recording current in the recording mode and a bias current in the reproducing mode to the recording head 17 of the MR inductive head 10. In the MR inductive head 10, a bias magnetic field is applied to the MR element of the MR (magnetoresistive effect) head by the current flowing in the recording coil of the inductive head (inductive magnetic head) in the reproducing mode. [Effect] It is possible to realize a recording / reproducing circuit connectable to the coil bias type MR inductive head 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording / reproducing circuit for a magnetic head for recording / reproducing using a so-called composite type magnetic head having a magnetoresistive effect type magnetic head and an induction type head.

[0002]

2. Description of the Related Art In a magnetoresistive effect type magnetic head (hereinafter referred to as an MR head), its magnetically sensitive portion is composed of a magnetic thin film having a magnetoresistive effect, and the resistivity of this magnetic thin film is magnetic on a magnetic recording medium. A current (sense current) flows through the magnetic thin film because it changes depending on the signal magnetic field based on recording.
To detect the resistance change as a reproduction output voltage. Since this MR head has features such as high output, low crosstalk, and no speed dependency, it is used as a reproducing head for a hard disk drive (HDD), or a high-density recording / reproducing head such as a digital audio tape recorder. Is used as.

As an example of such an MR head, FIG.
A shield type MR head as shown in (1) is known.

[0004] In FIG 6, the shield-type MR head 100, the upper (or top) shield core 102 and the lower (or lower layer) shield core 103 and sandwiched by a space forming a predetermined reproduction gap G _R, An MR element 101, which is a magnetic sensitive section made of one or more magnetic thin films having a magnetoresistive effect, is provided.
1, a pair of electrodes 105a for allowing a direct current as a sense current to flow and extracting a resistance change as a voltage change,
105b is electrically connected. In addition, the MR element 1
Bias conductor 104 is provided in parallel with 01. The shield core 1 of such a shield type MR head 100
For 02 and 103, a single bulk magnetic material, a single-layer plated film, a sputtered film, or the like is mainly used.

FIG. 7 shows an example of a so-called MR inductive head, which is a composite type head in which an MR reproducing head and a normal inductive (induction type) magnetic recording head are combined. Since the configuration is similar to that of the example, the same reference numerals are given to corresponding portions and the description thereof will be omitted.

In FIG. 7, a magnetic core 106 is provided on the upper shield core 102 of the MR head portion with a predetermined recording gap G _W , and the magnetic core 106 is provided.
A spiral head winding 107 is provided so as to surround a magnetic coupling portion that is a connection portion with the shield core 102. In such an MR inductive head structure, the lower shield core 103 is provided on the base body or substrate 108 made of, for example, Al ₂ O ₃ —TiC, and the protective film layer 109 is laminated on the magnetic core 106 to form the gap. Is filled (or laminated) with a non-magnetic insulating material. The tip surface of the MR inductive head provided with the reproducing gap G _R and the recording gap G _W is a so-called ABS (air bearing surface) which is a surface facing a magnetic recording medium (for example, a hard disk).

FIG. 8 is a recording / reproducing IC (integrated circuit) for recording / reproducing using an MR inductive head which is a composite type head of a magnetoresistive head and an inductive magnetic head as shown in FIG. Shows an example.

In FIG. 8, the MR inductive head 110 has a structure as shown in FIG. 7, for example.
The MR element 111 and the bias conductor 114 in the inside are MR of FIG.
The recording head 117 in FIG. 8 corresponds to the element 101 and the bias conductor 104, respectively.
2. It corresponds to an inductive head structure composed of the magnetic core 106 and the head winding 107. These MR elements 1
11, the bias conductor 114 and the recording head 117 are M
Through the connection terminals T _{1 to} T ₆ of the R inductive head 110, the terminals T ₁₁ , T ₁₂ , T _{13 and the} like of the recording / reproducing IC (MR inductive head recording / reproducing circuit) 120 are connected. That is, one terminal T ₁ of the bias conductor 114 and one terminal T ₂ of the MR element 111 are grounded, and the other terminal T ₃ of the MR element 111 is connected to the W / R circuit section 130 via the terminal T ₁₁ of the recording / reproducing IC 120. Connected to the amplifier circuit 131 in the inside, and both terminals T ₄ and T ₅ of the magnetic head 117 are the terminals T ₁₂ and T _{12 of} the recording / reproducing IC 120.
Read / write via a T ₁₃ (R / W) Front circuit section 13
0 is connected to each driver circuit 132.
The signals at the terminals T ₁₁ , T ₁₂ and T ₁₃ are respectively MR (MR
0), INX (IN0X), and INY (IN0Y). In the example of FIG. 8, four (4 channels) units of such an MR inductive head 110 are connected. Since the bias conductor 114 shown in FIG. 8 corresponds to one end of the four bias conductors connected in series, one terminal T ₁ is grounded and the other terminal T ₆ is connected to the bias conductor of the adjacent head. There is. The other terminal of the bias conductor at the other end of the four bias conductors is connected to the bias current source 126 via the terminal T ₃₁ of the recording / reproducing IC 120.

Next, the structure and operation of the recording / reproducing IC 120 will be described. The amplifier circuit 131 in the reproduction / recording front circuit unit 130 is a first-stage amplifier that amplifies the reproduction output from the MR head. Since the MR head is single-ended with one side grounded, the amplifier circuit 131 has a single-ended input and differential output. Has become. The reproduction output signal from the amplifier circuit 131 is the amplifier 121 which is the second-stage amplifier.
Are further amplified by and are taken out as signals RDY and RDX from the terminals T ₂₂ and T ₂₃ , respectively. The driver circuit 132 is a recording current driver and supplies a recording current to the recording head 117 during recording. These amplifier circuits 131
The driver circuits 132 are provided in four sets corresponding to the above four heads.

Mode control circuit 1 in recording / reproducing IC 120
22 to the playback / recording switching control signal R via a terminal T _24.
/ W, and the power save signal PS is supplied via the terminal T ₂₅ . This mode control circuit 122
Has a function of turning on a necessary circuit and turning off an unnecessary circuit in each of the reproduction / recording / power saving modes. When the reproduction / recording switching control signal R / W is "H" (high level), as shown in A of FIG. 9, the reproduction (R) mode is set, and the amplifier circuit 131, the amplifier 121, and the bias current source 126 are turned on. The driver circuit 132 and the T-type flip-flop (T-FF) 12 are turned on.
4 and the recording current source 125 are turned off. When the reproduction / recording switching control signal R / W is "L" (low level), the recording (W) mode is set. Contrary to the above reproduction mode,
Amplifier circuit 131, amplifier 121, and bias current source 1
26 is turned off, and the driver circuit 132 and the T-FF124
And the recording current source 125 is turned on. When the power save signal PS is "H" (high level), the power save (PS) mode is set, and all but the mode control circuit 122 are turned off, and the power consumption is kept low.

The head selection circuit 123 has a function of selecting a head to be used, and two (2-bit) selection control signals HS1 and HS0 supplied to terminals T ₂₆ and T ₂₇ , respectively.
Only the set of the amplifier 131 and the driver 132 corresponding to the head selected by the combination of is turned on. T-
An FF (T-type flip-flop) 124 is a flip-flop that switches the direction in which a recording current flows at the time of recording, and the write data signal WDI supplied to the terminal T ₂₈ is "H" →
The fall of "L" is used as a trigger to change the direction of the recording current to I.
Alternately switch between NX → INY and INY → INX.
The recording current source 125 is a circuit that sets the value of the recording current.
The recording current is set according to the control voltage WC obtained by the recording current setting resistor 125R connected to the terminal T ₂₉ .
Specifically, a recording current inversely proportional to the resistance value of the resistor 125R is passed from the driver 132 to the MR element 111. The bias current control circuit 126 is a circuit that sets the value of the bias current, and the bias current IB proportional to the bias current setting voltage IBC supplied to the terminal T ₃₀ is supplied to the four bias conductors 114 and the like via the terminal T ₃₁ . Flowed in a series circuit. In addition, although not shown, a sense current setting circuit for setting the value of the sense current is provided, and a sense current proportional to the sense current setting voltage from the outside is supplied to the amplifier circuit 13.
1 to the MR element 111.

9A shows the recording / reproducing mode switching control signal described above, and FIG. 9B shows the recording head 117.
9 shows the recording current supplied to (the recording coil 107), and C in FIG. 9 shows the bias current supplied to the bias conductor 114. I _W in B of FIG. 9 indicates the recording current value, and the sign of +/− indicates the direction of current (INX → INY or INY → INX). I _bias in C of FIG. 9 indicates a bias current value. In the example of FIG. 9, reproduced from the recording (W) mode at time t ₁ in (R) mode shows a case to be switched from each of the reproduction mode to the recording mode at time t _2.

[0013]

Regarding the MR head and the MR inductive head as described above, the MR head has a narrower gap as the recording density of the recording medium increases.
Development is progressing in many fields, centering on narrowing tracks.

By the way, the applicant of the present invention previously filed Japanese Patent Application No. 3-
In the specification and drawings of No. 208189, a composite magnetic head of a type (so-called coil bias type) in which a bias magnetic field is generated by a current flowing through a coil of an inductive head for recording is proposed in a current bias type MR head. .

In order to use this type of magnetic head, not only a recording current is applied to the recording coil of the inductive head in the recording mode, but also the MR is used in the reproducing mode.
A bias current must be passed to apply a bias magnetic field to the device.

However, in the conventional recording / reproducing IC,
At the time of reproduction, the recording current driver is turned off, so that the current cannot flow through the recording coil.

The present invention has been made in view of the above circumstances, and recording on a composite magnetic head having a magnetoresistive head (MR head) and an inductive magnetic head (inductive head). It is an object of the present invention to provide a recording / reproducing circuit for a magnetic head that allows a bias current as well as a recording current to flow in a coil.

[0018]

A magnetic head recording / reproducing circuit according to the present invention comprises a recording circuit section for supplying a recording signal to the magnetic head and a reproducing circuit section for taking out a reproduced signal from the magnetic head. In a magnetic head recording / reproducing circuit having, a magnetoresistive head and an inductive magnetic head are provided as the magnetic head, and the magnetoresistive effect head is provided by a current flowing through (the recording coil of) the inductive magnetic head. A composite magnetic head having a structure in which a bias magnetic field is applied to the magnetoresistive element of the head is used, and a bias current for supplying a recording current in the recording mode to the induction magnetic head and generating a bias magnetic field in the reproducing mode is used. By providing the current supply means for supplying, the above-mentioned subject is solved.

The current supply means selects and outputs the recording current source, the bias current source, and the output current from the recording current source in the recording mode and the output current from the bias current source in the reproducing mode. A switch and a switch are conceivable. Further, the current supply means is a recording current setting means, a bias current setting means,
A switching switch which is switch-connected to the recording current setting means in the recording mode, and a switching switch which is switching-connected to the bias current setting means in the reproducing mode, and a current having a value set by the current setting means which is switching-connected to the switching switch is output. And a current source that operates.

[0020]

In the reproducing mode, a bias magnetic field can be applied to the magnetoresistive effect element of the magnetoresistive head by applying a bias current to (the recording coil of) the inductive magnetic head.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block circuit diagram showing a schematic configuration of an embodiment of a magnetic head recording / reproducing circuit according to the present invention. 2 and 3 show the MR of FIG.
(Magnetoresistive effect type) inductive head 1
3A and 3B are a cross-sectional view and a plan view showing a composite type magnetic head usable as 0.

First, in FIG. 1, the MR element 11 of the MR inductive head 10 is connected to a terminal T ₁₁ of a recording / reproducing IC (integrated circuit) 20 as a recording / reproducing circuit for a magnetoresistive magnetic head, so-called MR head. Has been done. As will be described later, the MR inductive head 10 has an MR head and an inductive head, and has a structure in which a bias magnetic field is applied to the MR element of the MR head by a current flowing through the recording coil of the inductive head.

The structure and operation of the recording / reproducing IC 20 shown in FIG. 1 will be described. An amplifier circuit 31 in the reproducing / recording front circuit section 30 is a first-stage amplifier for amplifying a reproduction output from the MR head, and the MR head is grounded on one side. Since it is a single end, the amplifier circuit 31 is a single end input and the output is differential. The reproduction output signal from the amplifier circuit 31 is further amplified by the amplifier 21, which is the second-stage amplifier, and the signal RD is output from the terminals T ₂₂ and T ₂₃ , respectively.
It is taken out as Y and RDX. The driver circuit 32 is
It is a recording current driver and supplies a recording current to the recording head 17 during recording. The amplifier circuit 31 and the driver circuit 32 are provided in four sets corresponding to, for example, four heads (for four channels).

A mode control circuit 22 in the recording / reproducing IC 20.
To the playback / recording switching control signal R / W via a terminal T _24.
However, the power save signal PS is also supplied via the terminal T ₂₅ . The mode control circuit 22 has a function of turning on a necessary circuit and turning off an unnecessary circuit in each of the reproduction, recording, and power saving modes. When the reproduction / recording switching control signal R / W is "H" (high level), the reproduction (R) mode is set, the amplifier circuit 31, the amplifier 21 and the bias current source 26 are turned on, and the driver circuit 32, the T-type flip-flop circuit. (T-F
F) 24 and recording current source 25 are turned off. When the reproduction / recording switching control signal R / W is "L" (low level), the recording (W) mode is set. Contrary to the reproducing mode, the amplifier circuit 31, the amplifier 21, and the bias current source 2 are set.
6 is turned off, and the driver circuit 32, the T-FF 24, and the recording current source 25 are turned on. Power save signal PS
When is "H" (high level), power save (PS)
The mode is entered, and all but the mode control circuit 22 are turned off to keep power consumption low.

The head selection circuit 23 is a circuit for selecting head used, the head selected by the two (2 bits) combination of the selection control signal HS1, HS0 of which are supplied to the terminal T _26, T ₂₇ Corresponding amplifier circuit 3
Only the set of 1 and the driver 32 is ON-controlled. T-FF
A (T-type flip-flop) 24 is a flip-flop for switching the direction of flow of a recording current at the time of recording, and has a terminal T _28.
Of the write data signal WDI supplied to the "H" → "L"
Of the recording current in INX →
Alternately switch between INY and INY → INX.

The recording current source 25 is a circuit for setting the value of the recording current. The recording current setting resistor 2 connected to the terminal T ₂₉ is used.
The recording current is set according to the control voltage WC obtained by 5R. The recording current source 25 outputs a recording current inversely proportional to the resistance value of the resistor 25R, and the changeover switch 35
Of the selected terminal a. Bias current control circuit 2
6 is a circuit for setting the value of the bias current,
_The bias current IB proportional to the bias current setting voltage IBC supplied to the ₃₀ is applied to the selected terminal b of the changeover switch 35.
Is supplied to. The change-over switch 35 is switch-controlled by a change-over control signal from the mode control circuit 22. In the recording (W) mode, the change-over switch 35 is switch-connected to the selected terminal a and the recording current from the recording current source 25 is changed. Is supplied to the recording head 17 (recording coil of the recording head 17) via the driver 32, and is switched and connected to the selected terminal b in the reproduction (R) mode, and the bias current from the bias current source 26 is supplied to the recording head 17 (recording coil of ) To.

Next, a specific example of the MR inductive head 10 connected to the recording / reproducing IC 20 will be described with reference to FIGS. The MR inductive head shown in FIGS. 2 and 3 is a composite magnetic head proposed by the applicant in the specification and drawings of Japanese Patent Application No. 3-208189.

2 and 3, the MR (magnetoresistive effect) element 1 is arranged between the thin film magnetic cores 2 and 3 forming a magnetic gap G between the front ends. These thin film magnetic cores 2 and 3 are laminated on a base body 8 called a slider made of, for example, Al ₂ —TiC so as to face each other with a predetermined gap.

The magnetic core 3 is a so-called ABS (air.
One end of the bearing surface is exposed, and the bearing surface is provided so as to extend in a direction substantially orthogonal to the ABS. The thin film core 2 is provided so that one end thereof faces the ABS and extends in a direction substantially orthogonal to the ABS, and a gap between the thin film core 2 and the magnetic core 3 is formed at a front end portion facing the ABS. It is bent so as to narrow. A magnetic gap G, which functions as a recording gap, faces the ABS between the front ends. The magnetic core 2 magnetically contacts the magnetic core 3 at the rear end to form a back gap and a closed magnetic path.

The MR element 1 is formed as a rectangular pattern slightly narrower than the track width Tw of the magnetic gap G, and is arranged rearward from the ABS in the magnetic gap. A pair of electrodes 5a and 5b for passing a so-called sense current is electrically connected to the MR element 1 and laminated at the front end and the rear end of the MR element 1. The MR element 1 is provided on the magnetic core 3 via a first insulating layer 6a for insulation from the magnetic core 3. The end of the wiring pattern drawn out from the electrode 5a on the tip side to the back side is the ground side terminal 5aa, and the end of the wiring pattern drawn to the back side from the electrode 5b on the back end side is the sense current source side. Terminal portion 5bb.

A spiral recording coil (head coil) 7 is provided behind the electrode 5b on the rear end side so as to surround the magnetic coupling portion 2a which is a connection portion of the magnetic cores 2 and 3. The head coil 7 serves to supply a current according to the recording information to the magnetic path formed by the magnetic cores 2 and 3 in the recording mode, and M in the reproducing mode.
It functions as a bias conductor that gives the R element 1 a magnetized state in a desired direction. The head coil 7 is embedded with a second insulating layer 6b and a third insulating layer 6c in order to ensure insulation with the electrodes 5a, 5b, the MR element 1 and the magnetic core 2. Further, the ends of the wiring pattern led out from both ends of the head coil 7 serve as terminals 7a and 7b for supplying the recording current and bias current to the head coil 7.
A protective film layer 9 is laminated on the magnetic core 2 in order to protect the head structure configured as described above.

In the composite magnetic head (MR inductive head) configured as described above, a direct current is supplied as a bias current to the head coil 7 instead of the bias conductor, so that the MR element 1 can be oriented in a desired direction. Since it has a configuration that gives a magnetized state, it can be expected to reduce terminal suction as much as the bias conductor is no longer needed.
The arrangement area can be reduced and the head can be downsized. Therefore, it is suitable for a magnetic head for a hard disk, for example, which is required to be downsized and have a large recording capacity.

Next, FIG. 4 shows the recording / reproducing IC 20 of FIG.
Is used to show an example of a current passed through the recording coil of the MR inductive head 10 (for example, the head coil 7 having the configuration of FIGS. 2 and 3).

That is, the reproducing / recording (R / W) mode changes from W to R at time t ₁ and R at time t ₂ as shown in A of FIG.
When switched from W to W respectively, the recording coil is supplied with an alternating recording current varying between + Iw and −Iw in the recording mode as shown in B of FIG. 4, and a predetermined value + I _bias in the reproducing mode. The DC bias current of is applied. These currents are supplied to the changeover switch 35 shown in FIG.
By the switching control of (1), it is supplied from the recording current source 25 in the recording mode and from the bias current source 26 in the reproducing mode.

Next, another embodiment of the magnetic head recording / reproducing circuit according to the present invention will be described with reference to FIG. In FIG. 5, parts corresponding to the respective parts of the configuration shown in FIG. 1 are designated by the same reference numerals, and description thereof will be omitted.

In the embodiment shown in FIG. 5, one recording / bias current source 37 for supplying a recording current and a bias current is provided as a current source.
7, the recording current setting resistor 25R and the bias current setting resistor 26R are selected by the changeover switch 36 and connected. That is, the recording current setting resistor 25R is connected to the selected terminal a of the changeover switch 36 via the terminal T ₂₉ of the recording / reproducing IC 20, and the bias current setting resistor 26R is connected.
R is connected to the selected terminal b of the changeover switch 36 via the terminal T ₃₀ of the recording / reproducing IC 20. The changeover switch 36 is connected to the current setting voltage input terminal of the recording / bias current source 37, and the output current from the recording / bias current source 37 is sent to the driver 32.

In the structure shown in FIG. 5, in the recording (W) mode, the change-over switch 36 is switch-connected to the selected terminal a side, and the recording current setting resistor 25R is connected to the recording / bias current source 37, and The recording current is supplied to the driver 32. On the other hand, in the reproduction (R) mode, the changeover switch 36 is changed over and connected to the selected terminal b side.
The bias current setting resistor 26R is connected to the recording / bias current source 37, and the bias current is supplied to the driver 32. The other operations are similar to those of the embodiment shown in FIG.

The present invention is not limited to the above-described embodiment, and for example, the specific structure of the magnetic head is not limited to the examples of FIGS. 2 and 3, and the magnetic structure connected to the recording / reproducing IC 20 is not limited. The number of heads (the number of channels) is not limited to four.

[0039]

As is apparent from the above description, according to the present invention, the recording circuit section for supplying the recording signal to the magnetic head and the reproducing circuit section for taking out the reproduced signal from the magnetic head are provided. In a magnetic head recording / reproducing circuit having, a magnetoresistive head and an inductive magnetic head are provided as the magnetic head, and the magnetoresistive effect head is provided by a current flowing through (the recording coil of) the inductive magnetic head. Using a composite type magnetic head having a configuration in which a bias magnetic field is applied to the magnetoresistive effect element of the head, the induction type magnetic head,
Since a current supply means for supplying a recording current in the recording mode and a bias current for generating a bias magnetic field in the reproducing mode is provided, the bias current is supplied to (the recording coil of) the induction type magnetic head in the reproducing mode. A bias magnetic field can be applied to the magnetoresistive effect element of the magnetoresistive effect type head.

[Brief description of drawings]

FIG. 1 is a block circuit diagram showing a configuration of an embodiment of a magnetic head recording / reproducing circuit according to the present invention.

FIG. 2 is a sectional view showing an example of a schematic structure of an MR inductive head connected to the embodiment.

FIG. 3 is a plan view showing an example of a schematic structure of an MR inductive head connected to the embodiment.

FIG. 4 is a waveform diagram for explaining an example of a current supplied to a recording head of the MR inductive head of the one embodiment.

FIG. 5 is a block circuit diagram showing the configuration of another embodiment of the magnetic head recording / reproducing circuit according to the present invention.

FIG. 6 is a shield type M connected to a conventional recording / reproducing circuit.
It is a perspective view showing a schematic structure of a specific example of an R head.

FIG. 7 is a cross-sectional view showing a schematic configuration of a specific example of an MR inductive head connected to a conventional recording / reproducing circuit.

FIG. 8 is a block circuit diagram showing an example of a conventional magnetic head recording / reproducing circuit.

FIG. 9 is a waveform diagram for explaining an example of a current supplied to a recording head of a conventional MR inductive head.

[Explanation of symbols]

 1, 11 ... MR element 2, 3 ... Magnetic core 5a, 5b ... Electrode 7 ... Head winding 10 ... MR inductive head 17 ... ... Recording head 22 ... Mode control circuit 25 ... Recording current source 25R ... Recording current setting resistor 26 ... Bias current source 26R ... Bias Current setting resistor 31 ... Amplifier circuit 32 ... Driver 35, 36 ... Changeover switch

Claims (3)

[Claims] 1. A magnetic head recording / reproducing circuit comprising a recording circuit section for supplying a recording signal to a magnetic head, and a reproducing circuit section for taking out a reproduced signal from the magnetic head. A composite magnetic head having a magnetoresistive effect head and an inductive magnetic head, and applying a bias magnetic field to a magnetoresistive effect element of the magnetoresistive effect head by a current flowing through the inductive magnetic head, A recording / reproducing circuit for a magnetic head, characterized in that the induction type magnetic head is provided with a current supplying means for supplying a recording current in a recording mode and supplying a bias current for generating a bias magnetic field in a reproducing mode. 2. The current supply means selects a recording current source, a bias current source, an output current from the recording current source in the recording mode, and an output current from the bias current source in the reproducing mode. 2. The magnetic head recording / reproducing circuit according to claim 1, further comprising a changeover switch for taking out. 3. The current supplying means is a recording current setting means, a bias current setting means, and a switching connection to the recording current setting means in a recording mode, and a switching connection to the bias current setting means in a reproducing mode. 2. The magnetic head recording / reproducing circuit according to claim 1, further comprising a switch and a current source for outputting a current having a value set by a current setting means switched and connected to the changeover switch.