magnetic recording and reproducing device

Abstract

To provide a magnetic recording / reproducing device capable of reducing the transfer of contaminants to a magnetic head.SOLUTION: A magnetic recording / reproducing device 1 includes: a disk-shaped magnetic recording medium 2; a motor 3 for rotationally driving the magnetic recording medium 2; a magnetic head 4 having a magnetic head element for reading information and a magnetic head element for writing the information with respect to the magnetic recording medium 2; and a bias circuit for supplying a predetermined bias voltage to the magnetic head element for reading the information. The magnetic recording medium has a magnetic layer and a carbon protection layer in this order on a substrate. The bias circuit supplies a voltage of -0.2 V to -1.0 V with respect to the potential of the magnetic recording medium to the magnetic head elements.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a magnetic recording and reproducing device. [Background technology]

[0002] Magnetic recording and playback devices are widely used to record and store various types of data on recording media such as hard disk drives and various recording media. Magnetic recording and playback devices are equipped with magnetic heads used to read and write information from and to the magnetic recording media. The magnetic heads consist of a write head and a read head, and read and write information while floating and traveling over the surface of the magnetic recording media.

[0003] The write head is an electromagnet that combines a coil and a magnetic material, and as the access area becomes smaller, a thin film head is used in which the coil is formed on the surface of the magnetic material by etching.

[0004] Read heads include MR (Magneto Resistive) heads, which have high sensitivity due to the magnetoresistance effect, GMR (Giant Magneto Resistive) heads, which use the giant magnetoresistance effect, and TMR (Tunnel Magneto Resistive) heads, which use the tunnel magnetoresistance effect. Of these, TMR heads have a basic structure in which a TMR element is sandwiched between two electrodes, and read magnetic information by changing the current between these two electrodes.

[0005] A voltage of about 0.2 V is normally applied between the two electrodes, which are exposed on the surface facing the magnetic recording medium. Therefore, in order to prevent discharge with the magnetic recording medium, for example, a magnetic disk memory device has been disclosed in which one end of the electrode is connected to the magnetic recording medium, thereby making the two electrodes substantially equal in potential (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Republished Patent No. WO00 / 057404 Summary of the Invention [Problem to be solved by the invention]

[0007] The flying height of a magnetic head is becoming smaller as the recording density of magnetic recording media increases. When the flying height of a magnetic head is small, even the slightest contaminant or environmentally derived chemical substance is present on the magnetic recording medium, and the contaminant adheres to or is transferred to the magnetic head due to contact or close floating between the magnetic recording medium and the magnetic head. Such contaminant on the magnetic head not only deteriorates the recording / reproducing characteristics of the magnetic head, but also impairs the flying stability of the magnetic head, and may even cause damage to the magnetic head.

[0008] One aspect of the present invention has been made in view of the above circumstances, and has an object to provide a magnetic recording and reproducing device that can reduce the transfer of contaminants to a magnetic head. [Means for solving the problem]

[0009] One aspect of the magnetic recording and reproducing device according to the present invention comprises a disk-shaped magnetic recording medium, a motor for rotating the magnetic recording medium, a magnetic head having a magnetic head element for reading information from the magnetic recording medium and a magnetic head element for writing the information, and a bias circuit for supplying a predetermined bias voltage to the magnetic head element for reading the information, wherein the magnetic recording medium has a magnetic layer and a carbon protective layer in that order on a substrate, and the bias circuit supplies a voltage of -0.2V to -1.0V relative to the potential of the magnetic recording medium to the magnetic head element. [Effects of the Invention]

[0010] One aspect of the magnetic recording and reproducing device according to the present invention can reduce the transfer of contaminants to the magnetic head. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic diagram showing the configuration of a magnetic recording and reproducing device according to an embodiment of the present invention. [Figure 2] FIG. 1 is a diagram schematically illustrating a magnetic recording medium and a magnetic head. [Figure 3] FIG. 10 is a diagram showing the relationship between the potential difference between a magnetic head and a magnetic recording medium and Δ touchdown power. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present invention will be described in detail. To facilitate understanding of the description, the same components in each drawing will be assigned the same reference numerals, and duplicate explanations will be omitted. The scale of each member in the drawings may differ from the actual scale. In this specification, unless otherwise specified, "to" indicating a range of values ​​means that the values ​​before and after it are included as the lower and upper limits.

[0013] <Magnetic recording and playback device> A magnetic recording and reproducing device according to an embodiment of the present invention includes a disk-shaped magnetic recording medium, a motor for rotating the magnetic recording medium, a magnetic head element for reading or writing information from or to the magnetic recording medium, and a bias circuit for supplying a predetermined bias voltage to the magnetic head element for reading information, the magnetic recording medium having a magnetic layer and a carbon protective layer in that order on a substrate, and the bias circuit for supplying a voltage to the magnetic head element within a range of −0.2 V to −1.0 V relative to the potential of the magnetic recording medium. The magnetic recording and reproducing device according to this embodiment has the above-described configuration, thereby reducing contamination and damage to the magnetic head due to contamination of the magnetic recording medium.

[0014] It was believed that contaminants present on the surface of magnetic recording media were often introduced from the outside (for example, the surrounding environment or handling of the magnetic recording media) during the manufacturing process of the magnetic recording media, and therefore attempts have been made to reduce the contaminants present on the surface of magnetic recording media by making the manufacturing environment of the magnetic recording media cleaner.

[0015] On the other hand, the recording density required for magnetic recording and reproducing devices is increasing, and the flying height of the magnetic head above the surface of the magnetic recording medium is becoming smaller and smaller. As a result, extremely small contaminants that cannot be removed using conventional methods are beginning to become a problem.

[0016] The present inventors analyzed the causes of minute contaminants adhering to magnetic heads and found that a significant proportion of the contaminants are products of carbon and carbon nitride generated in the carbon protective layer of magnetic recording media, and that these contaminants adhere to the magnetic head due to the potential between the magnetic recording medium and the magnetic head. They also found that these contaminants have a negative charge and are easily attached to the magnetic head due to the potential between the magnetic recording medium and the magnetic head. The present inventors found that by providing a bias circuit that supplies a predetermined bias voltage to the magnetic head element that reads information, and by using this bias circuit to supply the magnetic head element with a voltage within the range of -0.2V to -1.0V relative to the potential of the magnetic recording medium, it is possible to reduce the adhesion of contaminants originating from the carbon protective layer of the magnetic recording medium to the magnetic head.

[0017] Fig. 1 is a schematic diagram showing the configuration of a magnetic recording and reproducing device according to an embodiment of the present invention. As shown in Fig. 1, the magnetic recording and reproducing device 1 according to this embodiment includes a disk-shaped magnetic recording medium 2, a motor 3 that rotates the magnetic recording medium 2, a magnetic head 4 that reads and writes information from and to the magnetic recording medium 2, and a ramp mechanism 5 that retracts the magnetic head 4 from above the magnetic recording medium 2.

[0018] Note that Figure 1 shows a state in which information is being read from or written to the magnetic recording medium 2 using a magnetic head 4. The magnetic head 4 is levitated vertically above the main surface of the magnetic recording medium 2 by air vortices generated by the rotation of the magnetic recording medium 2 by a motor 3, and is driven in a direction parallel to the surface of the magnetic recording medium 2 by a voice coil motor 7.

[0019] Fig. 2 is a diagram schematically showing a magnetic recording medium 2 and a magnetic head 4. As shown in Fig. 2, the magnetic recording medium 2 includes a non-magnetic substrate 21, a magnetic layer 22, a carbon protective layer 23, and a lubricant layer 24 laminated in this order on the non-magnetic substrate 21. The magnetic recording medium 2 is also grounded.

[0020] The magnetic head 4 is provided at the tip of a gimbal 9 of a head assembly 8. The magnetic head 4 has a magnetic head element 41A that reads information from the magnetic recording medium 2, a magnetic head element 41B that writes information to the magnetic recording medium 2, and a pair of electrodes 42A and 42B. The pair of electrodes 42A and 42B are connected to a preamplifier 43, and an output signal from the magnetic head element 41A that reads information is sent to the preamplifier 43. A bias circuit 44 is connected to wiring L1 that connects the electrode 42A and the preamplifier 43. The bias circuit 44 applies a voltage in the range of −0.2 V to −1.0 V with respect to the ground potential of the magnetic recording medium 2 to the electrodes 42A and 42B.

[0021] The resistance of the magnetic head element 41A that performs reading is normally about 20 Ω, and the bias current flowing therethrough is about 10 mA, so that a potential difference of about 0.2 V occurs between the electrodes 42A and 42B of the magnetic head element 41A.

[0022] In general, in a magnetic recording and reproducing device, one end of the electrode of the magnetic head element is connected to the magnetic recording medium to prevent discharge between the magnetic recording medium and the magnetic head element, and therefore, a potential difference of 0 to 0.2 V in absolute value occurs between the magnetic head elements 41A and 41B and the magnetic recording medium 2, and a potential difference of 0 to 0.2 V in absolute value occurs between both electrodes of the magnetic head element.

[0023] On the other hand, the inventors of the present invention have found that even if the potential difference of 0 to 0.2 V generated between the magnetic head elements 41A and 41B and the magnetic recording medium 2 is negative, this potential difference is unlikely to be sufficient to prevent negatively charged carbon and carbon nitride contaminants generated from the carbon protective layer 23 from adhering to the magnetic head 4. To prevent contamination of the magnetic head 4, it is necessary to apply a negative potential to the magnetic head elements 41A and 41B that is 0.2 V or more, preferably 0.3 V or more, relative to the potential of the magnetic recording medium 2. The greater the negative potential between the magnetic head elements 41A and 41B and the magnetic recording medium 2, the more effectively the adhesion of negatively charged ionic substances, such as carbon and carbon nitride, generated from the carbon protective layer 23 can be reduced. However, if the negative potential is too large, other positively charged ionic substances may adhere, increasing the risk of discharge between the magnetic head elements 41A and 41B and the magnetic recording medium 2. Therefore, the negative potential between the magnetic head elements 41A and 41B and the magnetic recording medium 2 is set to an absolute value of 1.0V or less, preferably 0.7V or less.

[0024] Therefore, the magnetic head element 41A that reads information has a structure in which both ends are sandwiched between two electrodes 42A and 42B, and the magnetic head elements 41A and 41B and the electrodes 42A and 42B as a whole have a potential in the range of -0.2V to -1.0V, more preferably -0.3V to -0.7V, relative to the ground potential of the magnetic recording medium 2.

[0025] The magnetic recording medium 2 may include other layers in addition to the non-magnetic substrate 21, magnetic layer 22, carbon protective layer 23, and lubricant layer 24. For example, the magnetic recording medium 2 may include an adhesion layer, a soft magnetic underlayer, a seed layer, an orientation control layer, etc. between the non-magnetic substrate 21 and the magnetic layer 22, as needed. The soft magnetic underlayer may include, for example, a first soft magnetic layer, an intermediate layer, and a second soft magnetic layer. The orientation control layer may be a single layer, or may be two or more layers (for example, a first orientation control layer, a second orientation control layer, etc.). Materials for forming the adhesion layer, soft magnetic underlayer, seed layer, orientation control layer, etc. may be materials commonly used in magnetic recording media.

[0026] The following describes an example of a method for manufacturing the magnetic recording medium 2. The method for manufacturing the magnetic recording medium 2 includes at least the steps of forming a magnetic layer 22 on a non-magnetic substrate 21, forming a carbon protective layer 23 on the magnetic layer 22, and forming a lubricant layer 24 on the carbon protective layer 23.

[0027] The non-magnetic substrate 21 may be a substrate made of a metal material such as Al or an Al alloy, on which a film made of NiP or a NiP alloy is formed, or may be a substrate made of a non-metal material such as glass, ceramics, silicon, silicon carbide, carbon, or resin, or a substrate made of such a non-metal material on which a film of NiP or a NiP alloy is formed.

[0028] The magnetic layer 22 may be made of a Co-Cr, Co-Cr-Ta, Co-Cr-Pt, Co-Cr-Pt-Ta, or Co-Cr-Pt-B-Ta alloy, etc. The magnetic layer 22 may be formed by any conventional method known in the art.

[0029] The thickness of the magnetic layer 22 is preferably 5 nm to 100 nm, more preferably 6 nm to 50 nm, and even more preferably 7 nm to 22 nm. If the thickness of the magnetic layer 22 is within the above preferred range, high recording density can be achieved.

[0030] In this specification, the thickness of the magnetic layer 22 refers to the length in the direction perpendicular to the main surface of the magnetic layer 22. The thickness of the magnetic layer 22 is, for example, the thickness measured at an arbitrary location on the cross section of the magnetic layer 22. If measurements are taken at several arbitrary locations on the cross section of the magnetic layer 22, the average value of the thicknesses measured at these locations may be used. Hereinafter, the same measurement method as for the thickness of the magnetic layer 22 can be used for other layers.

[0031] The magnetic layer 22 can be formed on the non-magnetic substrate 21 by a sputtering method or the like.

[0032] The magnetic layer 22 may be formed by stacking multiple layers. In this case, a non-magnetic layer may be included between each magnetic layer 22. The non-magnetic layer may be formed using a material commonly used in magnetic recording media. The magnetic layers 22 may be formed using the same type of material, or different types of materials.

[0033] The carbon protective layer 23 protects the magnetic layer 22 and also functions to improve the sliding properties of the magnetic head 4. The carbon protective layer 23 can be made of a conventionally known material such as carbon, carbon nitride, hydrogenated carbon, or hydrogenated carbon nitride.

[0034] The thickness of the carbon protective layer 23 is preferably in the range of 1 nm to 10 nm from the viewpoint of reducing magnetic spacing and durability when used in high-density recording conditions. Here, magnetic spacing refers to the distance between the element portion of the magnetic head 4 and the magnetic layer 22. The narrower the magnetic spacing, the better the electromagnetic conversion characteristics.

[0035] The carbon protective layer 23 is usually formed by a sputtering method using a carbon target material, a CVD (chemical vapor deposition) method using a hydrocarbon raw material such as ethylene or toluene, or an ion beam deposition (IBD) method, or may be formed by combining these methods to form a multi-layer structure.

[0036] The thickness of the lubricant layer 24 is preferably within the range of 1 nm to 3 nm.

[0037] The lubricant layer 24 can be formed using a liquid lubricant layer. The liquid lubricant layer is preferably one that is chemically stable, has low friction, and has low adsorption, and is preferably a fluororesin-based lubricant such as a perfluoropolyether-based lubricant containing a compound having a perfluoropolyether structure.

[0038] The lubricant layer 24 can be formed on the carbon protective layer 23 by a coating method or the like.

[0039] As described above, the magnetic recording and reproducing device 1 includes a magnetic recording medium 2 having a magnetic layer 22 and a carbon protective layer 23 in this order on a non-magnetic substrate 21, a motor 3, a magnetic head 4 having magnetic head elements 41A and 41B, and a bias circuit 44. The bias circuit 44 supplies a voltage of −0.2 V to −1.0 V to the magnetic head elements 41A and 41B relative to the potential of the magnetic recording medium 2. The magnetic recording and reproducing device 1 can reduce the adhesion of negatively charged ionic substances, such as carbon and carbon nitride, generated from the carbon protective layer 23 to the magnetic head elements 41A and 41B, and can also reduce the adhesion of other positively charged ionic substances to the magnetic head elements 41A and 41B. Therefore, the magnetic recording and reproducing device 1 can reduce the transfer of contaminants, such as ionic substances, to the magnetic head 4. This allows the magnetic recording and reproducing device 1 to reliably read and write information, thereby achieving stable magnetic recording and reproducing characteristics. Furthermore, the magnetic recording and reproducing device 1 can make it difficult for contamination and damage to the magnetic head 4 caused by contamination of the magnetic recording medium 2 to occur, and therefore can have excellent environmental resistance.

[0040] The magnetic recording and reproducing device 1 can supply a voltage of −0.3 V to −0.7 V to the magnetic head elements 41A and 41B. This allows the magnetic recording and reproducing device 1 to further reduce adhesion of negatively charged ionic substances such as carbon and carbon nitride generated from the carbon protective layer 23 and other positively charged ionic substances to the magnetic head elements 41A and 41, thereby more reliably reducing the transfer of contaminants to the magnetic head 4.

[0041] By having the above-described characteristics, the magnetic recording and reproducing device 1 can be used while reducing the transfer of contaminants to the magnetic head 4 even when the distance between the magnetic head and the magnetic recording medium is reduced and the flying height of the magnetic head is further reduced. Therefore, the magnetic recording and reproducing device 1 can be suitably used in magnetic recording and reproducing devices with even higher recording densities. [Example]

[0042] Hereinafter, the embodiment will be described in more detail with reference to examples and comparative examples, but the embodiment is not limited to these examples and comparative examples.

[0043] (Magnetic Recording Media Manufacturing) A cleaned glass substrate (HOYA, 2.5-inch diameter) was placed in the deposition chamber of a DC magnetron sputtering device (C-3040, Anelva) and subjected to an ultimate vacuum of 1×10 -5 The film formation chamber was evacuated until the pressure reached 100 Pa.

[0044] Thereafter, an adhesive layer having a thickness of 10 nm was formed on the glass substrate by sputtering using a Cr target.

[0045] Next, a soft magnetic underlayer was formed on the adhesion layer by sputtering. The soft magnetic underlayer consisted of a first soft magnetic layer, an intermediate layer, and a second soft magnetic layer. First, a 25-nm-thick first soft magnetic layer was formed using a target of Co-20Fe-5Zr-5Ta (Fe content: 20 atomic %, Zr content: 5 atomic %, Ta content: 5 atomic %, remainder: Co) at a substrate temperature of 100°C or less. Next, a 0.7-nm-thick intermediate layer made of Ru was formed on the first soft magnetic layer. Then, a 25-nm-thick second soft magnetic layer made of Co-20Fe-5Zr-5Ta was formed on the intermediate layer.

[0046] Next, a seed layer having a thickness of 5 nm was formed on the soft magnetic underlayer by sputtering using a Ni-6W {W content: 6 atomic %, remainder Ni} target.

[0047] After that, a 10 nm thick Ru layer was formed on the seed layer as a first orientation control layer by sputtering at a sputtering pressure of 0.8 Pa. Next, a 10 nm thick Ru layer was formed on the first orientation control layer by sputtering at a sputtering pressure of 1.5 Pa as a second orientation control layer.

[0048] Next, a first magnetic layer consisting of 91(Co15Cr16Pt)-6(SiO2)-3(TiO2) {Cr content: 15 atomic %, Pt content: 16 atomic %, the remainder an alloy of Co 91 mol %, oxide made of SiO2 6 mol %, oxide made of TiO2 3 mol %} was formed on the second orientation control layer by sputtering at a sputtering pressure of 2 Pa to a thickness of 9 nm.

[0049] Next, a non-magnetic layer consisting of 88(Co30Cr)-12(TiO2) (Cr content 30 atomic %, remainder 88 mol % Co alloy, 12 mol % TiO2 oxide) was deposited on the first magnetic layer by sputtering to a thickness of 0.3 nm.

[0050] Then, a second magnetic layer consisting of 92(Co11Cr18Pt)-5(SiO2)-3(TiO2) (Cr content 11 atomic %, Pt content 18 atomic %, remainder Co alloy 92 mol %, oxide of SiO2 5 mol %, oxide of TiO2 3 mol %) was deposited on the non-magnetic layer by sputtering at a sputtering pressure of 2 Pa to a thickness of 6 nm.

[0051] Thereafter, a non-magnetic layer made of Ru was formed on the second magnetic layer by sputtering to a thickness of 0.3 nm.

[0052] Next, a third magnetic layer was deposited on the non-magnetic layer to a thickness of 7 nm by sputtering using a target consisting of Co-20Cr-14Pt-3B (Cr content 20 atomic %, Pt content 14 atomic %, B content 3 atomic %, remainder Co) at a sputtering pressure of 0.6 Pa.

[0053] Next, a protective layer made of carbon nitride (nitrogen content: 5 atomic %) was formed to a thickness of 3 nm by ion beam deposition.

[0054] Next, a 1.4 nm perfluoropolyether liquid lubricant was applied onto the third magnetic layer by dip coating to form a lubricating layer, thereby producing a magnetic recording medium.

[0055] (Seek evaluation of magnetic recording media) Using the magnetic recording medium, a magnetic recording / reproducing device with the structure shown in Figure 1 was fabricated and a seek evaluation was performed. The magnetic recording / reproducing device was filled with helium at a filling pressure of 532 torr. The magnetic recording / reproducing device was placed in a 60°C environment, the magnetic recording medium rotation speed was 7200 rpm, and the magnetic head was levitated at a radius of 32 mm. The potential difference between the high-potential side of the magnetic head element and the magnetic recording medium was varied as follows: +1.0 V, +0.8 V, +0.6 V, +0.4 V, 0, -0.3 V, -0.7 V, and -1.0 V. The magnetic head was levitated at a fixed point under each condition for 900 seconds, and the amount of contaminants adhering to the magnetic head was evaluated. The amount of contaminants was evaluated by measuring the delta touchdown power of the magnetic head.

[0056] Δtouchdown power refers to the power applied to a heater built into the magnetic head near the reading element when the reading element approaches the surface of the magnetic recording medium using the thermal expansion of the heater and finally touches down on the magnetic recording medium. The greater the amount of contaminants adhering to the magnetic head, the greater the absolute value of Δtouchdown power.

[0057] Figure 3 shows the relationship between the potential difference between the magnetic head and magnetic recording medium and the Δtouchdown power. As shown in Figure 3, when the potential difference between the high-potential side of the magnetic head element and the magnetic recording medium in absolute value terms was -0.7V and -1.0V, the Δtouchdown power was almost zero. From this figure, it can be said that by supplying a voltage to the magnetic head element that is -0.2V to -1.0V, more preferably -0.3V to -0.7V, relative to the potential of the magnetic recording medium, it is possible to reduce the adhesion of contaminants to the magnetic head.

[0058] Although the embodiments have been described above, they are presented as examples and the present invention is not limited to the above embodiments. The above embodiments can be implemented in various other forms, and various combinations, omissions, substitutions, modifications, etc. can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the inventions and their equivalents as set forth in the claims. [Explanation of symbols]

[0059] 1 Magnetic recording and playback device 2. Magnetic Recording Media 3 motors 4. Magnetic head 5 Ramp mechanism 7 Voice Coil Motor 8 Head Assembly 9. Gimbal 21 Non-magnetic substrate 22 Magnetic layer 23 Carbon protective layer 24 Lubricant layer 41A, 41B magnetic head element 42A, 42B electrode 43 Preamp 44 Bias circuit

Claims

[Claim 1] a disk-shaped magnetic recording medium; a motor that rotates the magnetic recording medium; a magnetic head having a magnetic head element for reading information from the magnetic recording medium and a magnetic head element for writing information to the magnetic recording medium; a bias circuit for supplying a predetermined bias voltage to the magnetic head element for reading the information; the magnetic recording medium has a magnetic layer and a carbon protective layer in this order on a substrate; The bias circuit supplies a voltage of −0.7 V to −1.0 V to the magnetic head element relative to the potential of the magnetic recording medium.

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