JPH097127A - Magnetic disk device provided with thin film magnetic head - Google Patents

Abstract

PURPOSE: To reduce noises and to make the device resistant to migration by keeping temperature of a magnetoresistance element lower than the Neel temperature of a ferromagnetic film by providing a control circuit to cause an electric current to flow in the direction to generate thermal absorption on a Peltier element at the time of reproducing with a ferromagnetic effect element. CONSTITUTION: A recording data applied to input terminals 26a, 26b is supplied to a write gate 25, and the write gate 25 supplies the recording data to a write circuit 27 only when the gate is instructed for a recording operation by a recording control signal supplied via a control terminal 36. The write circuit 27 causes a write current to flow in the coil 22 according to the data, and performs recording on a recording medium (not shown in the diagram) with an inductive type thin film magnetic head comprising the coil 22 and magnetic poles 19, 23. An electric current flows to a MR film 16 from a constant current circuit 30 only when a reproducing control signal supplied from a control terminal 35 instructs for a reproducing operation, and the signal reproduced by a MR type thin film magnetic head 29 is amplified 31 and then decoded by a decoding circuit 32, and the reproduced data obtained is outputted via output terminals 33a, 33b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk device having a magnetoresistive (MR) type thin film magnetic head having an antiferromagnetic film.

[0002]

2. Description of the Related Art In an inductive thin film magnetic head, there is known a technique of cooling a head by a Peltier element at the time of non-recording in order to reduce noise generation immediately after the start of reproduction. Kaihei 5-
54328).

In this known technique, the magnetic pole of the inductive thin film magnetic head is cooled by a Peltier element from the end of recording to the start of reproduction, and popcorn noise is forcibly generated during that period, and the generation of popcorn noise is substantially completed by the start of reproduction. To reduce the noise generation immediately after the start of reproduction, or by heating the magnetic poles of the inductive thin-film magnetic head with a Peltier element during recording and cooling it with a Peltier element from the end of recording to the start of reproduction. Reduce the noise generation immediately after the start of playback by increasing the temperature difference and forcibly generating popcorn noise between the end of recording and the start of playback and ending the generation of popcorn noise by the start of playback, or While recording the magnetic pole of the inductive thin film magnetic head, By cooling with a Peltier element from the end of recording to the start of reproduction, the temperature difference between the time of recording and after recording is eliminated to prevent the rapid contraction of the magnetic pole at the start of reproduction, thereby preventing popcorn noise from occurring immediately after the start of reproduction. It is designed to be reduced.

That is, in all of the above-mentioned known techniques, a Peltier element is provided to control the temperature of the magnetic pole of the inductive type thin film magnetic head, and the Peltier element is provided for the MR type thin film magnetic head having an antiferromagnetic film. It does not control cooling or temperature.

With the recent increase in recording density of magnetic disk devices, the MR height of the MR type thin film magnetic head has to be narrowed, and as a result, the amount of heat generated by the MR film is increasing. The larger the sense current flowing through the MR film, the larger the reproducing output of the head, but the amount of heat generated increases accordingly, which may cause migration, so that the sense current cannot exceed a certain limit. The higher the temperature of the current-carrying body, the more easily the migration occurs. For example, the Semiconductor Handbook Editorial Committee, “Semiconductor Handbook (2nd Edition)”, 567th.
See page 1977.

Further, an antiferromagnetic film is used in the MR element to control magnetic domains and suppress noise.
If the temperature of the R film becomes equal to or higher than the Neel temperature of the antiferromagnetic film even once, the antiferromagnetic film loses its antiferromagnetic property, and as a result, the noise suppressing effect of the MR film is lost. Furthermore, when a current is passed through the MR film and a large amount of heat is generated, the stress state applied to the MR film changes, which also causes noise.

Therefore, it is an object of the present invention to provide a magnetic disk drive equipped with a thin film magnetic head in which noise is reduced even when a large sense current is passed and migration is less likely to occur.

[0008]

According to the present invention, there is provided a magnetic disk having a thin film magnetic head including an MR element having an antiferromagnetic film, a slider provided with the MR element, and a gimbal for supporting the slider. An apparatus, comprising a Peltier element arranged on a slider or a gimbal in the vicinity of the MR element, and a control circuit for flowing a current in a direction in which heat is absorbed in the Peltier element during a reproducing operation by the MR element,
Provided is a magnetic disk device configured to keep the temperature of an MR element lower than the Neel temperature of an antiferromagnetic film.

The control circuit causes a current to flow in the Peltier element in a direction in which heat is absorbed during a reproducing operation in which a current flows through the MR element to generate heat. As a result, the MR element is cooled and its temperature is kept lower than the Neel temperature of the antiferromagnetic film. As a result, there is no fear that the antiferromagnetic effect of the antiferromagnetic film will be lost, and noise due to heat can be prevented. Moreover, since it becomes possible to flow a larger sense current than the conventional one, it is possible to obtain a magnetic disk device with less noise and a larger reproduction output.

It is preferable that the control circuit is configured to flow a current in a direction in which heat absorption occurs in the Peltier element when the reproduction control signal indicates a reproduction operation.

In one embodiment of the present invention, an inductive magnetic recording head is further provided, and the control circuit absorbs heat in the Peltier element during reproducing operation by the MR element and during recording operation by the inductive magnetic recording head. It is configured to pass an electric current in the direction in which it occurs.

In this case, the control circuit causes the current to flow in the direction in which heat is absorbed in the Peltier element when the reproduction control signal indicates the reproducing operation and when the recording control signal indicates the recording operation. It is preferably configured.

As a specific mounting method of the Peltier element, it is provided on the same surface as the MR element of the slider and on the lower layer or the upper layer of the MR element, or on the surface opposite to the air bearing surface of the slider. Preferably, it is provided or at the attachment part of the gimbal to the slider.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a sectional view schematically showing the structure of a magnetic head portion according to an embodiment of the present invention. This embodiment is a case where the present invention is applied to a magnetic disk device having a composite type thin film magnetic head having an MR reproducing head and an inductive magnetic recording head.

In FIG. 1, reference numeral 10 denotes a substrate which serves as a flying head slider. On the surface of the substrate 10, semiconductor films 12a and 12b constituting a Peltier element 12 are laminated and formed via an insulating film 11. Has been done. An insulating film 13 is laminated on the Peltier element 12, and a normal composite type thin film magnetic head is formed thereon.
That is, the lower shield film 14, the insulating film 15, the MR film 16, the leads 17, the insulating film 18, the lower magnetic pole 19, and the insulating film 20.
And 21, the coil conductor 22, the upper magnetic pole 23, and the protective film 2.
4 are sequentially stacked. Since these laminated structures except for the Peltier element 12 are known, their materials,
The description of the film thickness, the forming method, etc. is omitted.

The Peltier element 12 has a large thermoelectric performance index Z. For example, the semiconductor film 12a may be formed of Bi ₂ T
It is composed of a P-type semiconductor in which 5 to 25% of Sb ₂ Te ₃ is solid-dissolved in e ₃ and the semiconductor film 12b is 5 to 25 in Bi ₂ Te ₃ .
% Sb ₂ Se ₃ as a solid solution.
In this case, the maximum temperature change of the PN junction (cold junction) is about 7
It becomes 0 ° C. Further, the MR film 16 is usually provided with an antiferromagnetic film in order to suppress the generation of noise (not shown).

FIG. 2 is a block diagram showing an example of a recording / reproducing circuit of the magnetic disk device according to this embodiment. In the figure, 25 is a write gate for receiving recording data via input terminals 26a and 26b, 27 is a write circuit, 28 is an inductive thin film magnetic recording head composed of the magnetic poles 19 and 23 and the coil conductor 22 described above, Reference numeral 29 is an MR composed of the above-mentioned MR film 16 and the like.
Type thin film reproducing head, 30 is a constant current circuit for supplying a current to the MR type thin film reproducing head, 31 is an amplifier for amplifying the output voltage of the MR type thin film reproducing head, and 32 is reproducing data through output terminals 33a and 33b. A demodulation circuit 34, a control circuit 34 for the Peltier device 12, and 35 and 36 control terminals to which a reproduction control signal and a recording control signal are applied, respectively.

The recording data applied via the input terminals 26a and 26b is supplied to the write gate 25. The write gate 25 supplies the recording data to the write circuit 27 only when the recording control signal supplied via the control terminal 36 instructs the recording operation. The write circuit 27 applies a write current to the coil 22 in accordance with the recording data, and records on a recording medium (not shown) by an inductive thin film magnetic head composed of the coil 22 and the magnetic poles 19 and 23.

Only when the reproduction control signal supplied from the control terminal 35 indicates a reproduction operation, the constant current circuit 30 outputs M
A constant current flows through the R film 16. The signal reproduced by the MR thin film magnetic head 29 is amplified by the amplifier 31 and then demodulated by the demodulation circuit 32, and the reproduced data obtained is output through the output terminals 33a and 33b.

The Peltier element control circuit 34 in this embodiment has a structure as shown in FIG. 3, and a DC constant voltage circuit 34a, a switching transistor 34b and a current value are provided between the semiconductor films 12a and 12b of the Peltier element 12. A series circuit including the adjustment resistor 34d and a series circuit including the DC constant voltage circuit 34a, the switching transistor 34c, and the current value adjustment resistor 34e are connected in series. Control terminals 35 and 36 are connected to the gates of the switching transistors 34b and 34c, respectively.

When the recording control signal indicates the recording operation, the switching transistor 34c is turned on and the resistor 34e is turned on.
The constant current I _b adjusted by
Flows to The direction of this current is the direction in which the Peltier element 12 causes heat absorption. Further, when the reproduction control signal reproduction operation instruction, a constant current I _a to the switching transistor 34b is adjusted by the resistor 34d turned on flows through the Peltier element 12. The direction of this current is also the direction in which the Peltier element 12 absorbs heat.

During reproduction, the temperature of the head rises because a current flows through the MR film 16, and the temperature becomes T _RE ° C, for example. This current value flowing through the MR film 16 is constant and flows only during reproduction. Therefore, in the normal use state, the temperature of the head during reproduction is almost constant (T _RE ° C). Since a current flows through the coil 22 of the inductive recording head even during recording, the head temperature rises, for example, T _WR ° C. This recording current is constant, and the coil 2 is used only during recording.
It flows to 2. Therefore, in a normal use state, the temperature of the head during recording is constant (T _WR ° C). Similarly to A, the value of B is almost constant. Further, even when the magnetic disk device is in an operating state and recording / reproducing is not performed, the head temperature rises due to heat generation from the drive motor, frictional heat between the air and the disk, and the like. In a normal use condition, the temperature of the head at this time is almost constant and is T _DR ° C. However, this T _DR ℃ is set so that the condensation temperature of air <T _DR ℃ <Neil temperature of the antiferromagnetic film. Naturally, T _DR ° C <T _RE ° C and T _DR ° C <T _WR ° C.

As described above, in a normal magnetic disk device, the head temperature changes depending on the head usage condition, and the head temperature T _WR changes when the head usage condition is switched, for example, from recording to reproducing. ℃ to T _RE ℃
At the time of reproduction immediately after switching, the stress applied to the head changes due to this temperature change, and noise is generated. However, as in the present embodiment, the Peltier element 12 is provided, and further, the control circuit 34 causes a constant current I _{a in the} direction in which heat is absorbed in the Peltier element so that the temperature of the MR film becomes approximately T _DR ° C during reproduction. And a constant current _{Ib is} passed in a direction in which heat is absorbed in the Peltier element so that the temperature of the head becomes approximately T _DR ℃ even during recording. Temperature becomes almost constant. For this reason, the temperature of the MR film is kept lower than the Neel temperature of the antiferromagnetic film being used and kept above the dew condensation temperature of air in the magnetic disk device, and as a result, the antiferromagnetic effect of the antiferromagnetic film is obtained. It is not lost, noise is not generated by heat, and a larger current than that in the past can flow, so that a head with a large output can be provided.

FIG. 4 shows another embodiment of the present invention. FIG. 4A is a perspective view of a magnetic head slider and a suspension, and FIG. 4B is a side view thereof.

In the figure, 40 is a suspension, 4
Reference numeral 1 is a gimbal attached to the tip of the suspension 40, 42 is a magnetic head slider attached to the gimbal 41, and 43 is a magnetic disk.
The magnetic head according to the present embodiment is a composite thin film magnetic head including an MR reproducing head and an inductive magnetic recording head as in the case of the embodiment shown in FIG. 1, and its configuration is different from the mounting position of the Peltier element. Has the same configuration as the magnetic head of the embodiment of FIG. That is,
In the magnetic head of the embodiment shown in FIG. 1, the Peltier element is MR
Although laminated on a layer lower than the element (slider substrate side), in the present embodiment, the Peltier element 44 is formed as an upper layer of the MR element (and the inductive recording head), for example, on the protective film 24 of FIG. Has been done. of course,
The Peltier element 44 is provided near the MR element.

FIG. 5 is a sectional view showing the structure of the Peltier device 44 in this embodiment. Protective film 2 shown in FIG.
Semiconductor films 44a and 44b (composition etc. are the same as the semiconductor films 12a and 12 in the embodiment of FIG. 1) on a substrate 45 made of 4 or the like with an insulating film 46 (not necessarily in this embodiment) interposed therebetween.
b) are laminated, and the insulating film 47 is formed thereon. The semiconductor films 44a and 44b are connected to the Peltier device control circuit via the conductors 48a and 48b. The configuration and operation of this Peltier element control circuit are exactly the same as in the embodiment of FIG.

Since the operation and effect of this embodiment are exactly the same as those of the embodiment of FIG. 1, the description thereof will be omitted.

6A and 6B show another embodiment of the present invention. FIG. 6A is a perspective view of a magnetic head slider and a suspension, and FIG. 6B is a side view thereof.

In the figure, 60 is a suspension and 6
Reference numeral 1 is a gimbal attached to the tip of the suspension 60, 62 is a magnetic head slider attached to the gimbal 61, 63 is a magnetic disk, and 65 is a read / write element such as an MR element and an inductive magnetic recording element. This embodiment has exactly the same configuration as the embodiment of FIG. 4 except for the mounting position of the Peltier element. That is, in this embodiment, the Peltier element 64 is provided on the surface of the slider 62 opposite to the air bearing surface and in the vicinity of the MR element.

The operation and effects of this embodiment are exactly the same as those of the embodiment of FIG.

FIG. 7 shows still another embodiment of the present invention. (A) is a perspective view of a magnetic head slider and a suspension, and (B) is a side view thereof.

In the figure, 70 is a suspension and 7
Reference numeral 1 is a gimbal attached to the tip of the suspension 70, 72 is a magnetic head slider attached to the gimbal 71, 73 is a magnetic disk, and 75 is a read / write element such as an MR element and an inductive magnetic recording element. This embodiment has exactly the same configuration as the embodiment of FIG. 4 except for the mounting position of the Peltier element. That is, in this embodiment, the Peltier element 74 is provided on the gimbal 71 attached to the slider 72 in the vicinity of the MR element.

The operation and effects of this embodiment are exactly the same as in the case of the embodiment of FIG.

The embodiments described above are merely illustrative and not limitative of the present invention, and the present invention can be implemented in various other modified modes and modified modes. Therefore, the scope of the present invention is defined only by the claims and their equivalents.

[0036]

As described in detail above, according to the present invention, a thin film magnetic head including an MR element having an antiferromagnetic film, a slider provided with this MR element, and a gimbal for supporting the slider is provided. A magnetic disk device for
The MR element is provided with a Peltier element arranged on a slider or a gimbal, and a control circuit for flowing a current in a direction in which heat is absorbed in the Peltier element at the time of reproducing operation by the MR element. Since the temperature is lower than the Neel temperature of the film, noise is reduced even when a large sense current is applied, and migration is less likely to occur. That is, the control circuit causes a current to flow in the Peltier element in a direction in which heat is absorbed during a reproducing operation in which a current flows in the MR element to generate heat. As a result, the MR element is cooled and its temperature is kept lower than the Neel temperature of the antiferromagnetic film. As a result, there is no fear that the antiferromagnetic effect of the antiferromagnetic film will be lost, and noise due to heat can be prevented. Moreover, since it becomes possible to flow a larger sense current than the conventional one, it is possible to obtain a magnetic disk device with less noise and a larger reproduction output.

[Brief description of drawings]

FIG. 1 is a cross-sectional view schematically showing a configuration of a magnetic head portion in an embodiment of a magnetic disk device of the present invention.

FIG. 2 is a block diagram showing an example of a recording / reproducing circuit of the magnetic disk device in the embodiment of FIG.

FIG. 3 is a block diagram showing a Peltier device control circuit of FIG.

FIG. 4 is a perspective view and a side view of a magnetic head slider and a suspension according to another embodiment of the present invention.

5 is a sectional view showing the configuration of a Peltier device in the embodiment of FIG.

FIG. 6 is a perspective view and a side view of a magnetic head slider and a suspension according to still another embodiment of the present invention.

FIG. 7 is a perspective view and a side view of a magnetic head slider and a suspension according to still another embodiment of the present invention.

[Explanation of symbols]

 10 Substrate 11, 13, 15, 18, 20, 21 Insulating Film 12 Peltier Element 12a, 12b Semiconductor Film 14 Lower Shield Film 16 MR Film 17 Lead 19 Lower Magnetic Pole 22 Coil Conductor 23 Upper Magnetic Pole 24 Protective Film 25 Write Gate 26a, 26b Input terminal 27 Write circuit 29 MR thin film magnetic head 30 Constant current circuit 31 Amplifier 32 Demodulation circuit 33a, 33b Output terminal 34 Peltier element control circuit 35a, 35b Control terminal

Claims (8)

[Claims] 1. A magnetic disk device comprising a thin film magnetic head including a magnetoresistive effect element having an antiferromagnetic film, a slider provided with the magnetoresistive effect element, and a gimbal supporting the slider. The magnetoresistive effect element comprises a Peltier element arranged on the slider or the gimbal, and a control circuit for supplying a current in a direction in which heat is absorbed in the Peltier element during a reproducing operation by the magnetoresistive effect element. A magnetic disk device, wherein the temperature of the magnetoresistive element is kept lower than the Neel temperature of the antiferromagnetic film. 2. The control circuit is configured to flow a current in a direction in which heat absorption occurs in the Peltier element when a reproduction control signal directs a reproduction operation. The magnetic disk device described. 3. The magnetic head further comprises an inductive magnetic recording head, and the control circuit controls the Peltier element during a reproducing operation by the magnetoresistive effect element and during a recording operation by the inductive magnetic recording head. 3. The magnetic disk drive according to claim 1, wherein the magnetic disk drive is configured to flow an electric current in a direction in which heat absorption occurs. 4. The control circuit supplies a current in a direction in which heat is absorbed in the Peltier element when the reproduction control signal indicates a reproduction operation and when the recording control signal indicates a recording operation. 4. The magnetic disk drive according to claim 3, wherein the magnetic disk drive is configured as follows. 5. The Peltier element is provided on the same surface as the magnetoresistive effect element of the slider and in a lower layer of the magnetoresistive effect element. The magnetic disk device according to claim 1. 6. The Peltier element is provided on the same surface as the magnetoresistive effect element of the slider and in an upper layer of the magnetoresistive effect element. 2. The magnetic disk device according to item 1. 7. The magnetic disk device according to claim 1, wherein the Peltier element is provided on a surface of the slider opposite to the air bearing surface. 8. The magnetic disk device according to claim 1, wherein the Peltier element is provided in a mounting portion of the gimbal to the slider.