1. Field of the Invention
The present invention relates to a multi-channel thin-film magnetic head, and to a multi-channel magnetic tape drive apparatus with the multi-channel thin-film magnetic head.
2. Description of the Related Art
In the multi-channel magnetic tape drive apparatus, a multi-channel thin-film magnetic head with read head elements and write head elements for a large number of channels is provided. For example, in the multi-channel magnetic tape drive apparatus (the fourth generation) with the LTO (linear tape open) technical standard, a multi-channel thin-film magnetic head provided with read head elements of 16 channels, write head elements of 16 channels and servo magnetic head elements of 2 channels is used.
Recently, with enhancement in the performance of the multi-channel magnetic tape drive apparatus, required is adoption of a high performance write head element and a high performance read head element that are data transducers in each channel of the multi-channel thin film magnetic head. Also, required is a head structure for closely contacting a moving magnetic tape to a tape sliding surface of each data transducer, in other words for keeping a magnetic spacing between the magnetic tape and the sliding surface of the magnetic head as small as possible.
In a multi-channel tape drive apparatus, in typical, a magnetic tape bi-directionally moves for performing read and write operations. Thus, in most cases, two multi-channel thin film magnetic heads are arranged along a running path of the magnetic tape and each head is switched depending upon the moving direction of the tape.
In case of a flat type head with a flat sliding surface, a negative pressure will occur due to masking of air at a tape-approaching side edge of the sliding surface and due to discharging of air at a tape-leaving side edge of the sliding surface. By this negative pressure, the magnetic tape will make in contact with the sliding surface of the head. In this case, it is necessary to adjust with high precision a protruding amount of the head in a direction toward the magnetic tape, an angle of the sliding surface with respect to the magnetic tape surface (hereinafter called as inclination angle or taper angle), and an installation angle of the head.
However, for all the multi-channel thin film magnetic heads, it is extremely difficult to adjust their protruding amounts of the heads, the inclination angles and the installation angles of the heads to ideal values in this way. For example, when the protruding amount of the head in the direction toward the magnetic tape is small, when the inclination angle of the sliding surface of the head is too large or when the installation angle of the head inclines, at the tape-approaching side edge of the sliding surface, the magnetic tape does not touch the edge and thus the masking effect of air is lost, whereas at the tape-leaving side edge of the sliding surface, because an angle between the tape and the sliding surface becomes too large causing the discharge of air at this edge to be suppressed. If the discharge of air is limited at the tape-leaving side edge, the air is easy to pool between the tape and the sliding surface causing the magnetic spacing to increase.
U.S. Pat. No. 7,271,983 B2 (Saliba) discloses a magnetic head with outriggers arranged along the tape transport direction in a data island associated with a data transducer so as to reduce a head-tape separation or a magnetic spacing between the data transducer of the head and the magnetic tape.
However, even in case that the outriggers taught in Saliba is provided, if the inclination angle of the sliding surface becomes large, the magnetic tape never touches the edge at the tape-approaching side and thus the masking effect of air is lost causing the magnetic spacing to increase.
It is therefore an object of the present invention to provide a multi-channel thin-film magnetic head and a multi-channel magnetic tape drive apparatus, whereby a magnetic spacing can be minimized irrespective of a protruding amount of the head, an inclination angle of a sliding surface of the head and an installation angle of the head.
According to the present invention, a multi-channel thin-film magnetic head includes a head section provided with a plurality of thin-film magnetic head elements and a sliding surface for a magnetic tape, a slot section running in a direction perpendicular to a magnetic tape transport direction, the slot section being arranged adjacent to the head section in the magnetic tape transport direction, and an outrigger section provided with a sliding surface for the magnetic tape and arranged to separate from the head section by the slot section in the magnetic tape transport direction. The sliding surface of the outrigger section includes a sloped surface with a height that reduces as approaching the head section.
The outrigger section is provided outside of the head section to separate from the head-section sliding surface by a slot section, and the sliding surface of the outrigger section is inclined toward the head section so that a height of the outrigger section reduces as approaching the head section. Therefore, the sliding surface of the outrigger section has a minus inclination angle with respect to that of the sliding surface of the head section. Thus, a negative pressure occurs at this sliding surface of the outrigger section to allow the magnetic tape closely contact with this sliding surface. As a result, because the magnetic tape is guided to a position that is lower than the sliding surface of the head section, this magnetic tape comes into contact with an edge of the sliding surface of the head section. Thus, negative pressure occurs due to masking effect at the edge of the sliding surface of the head section, and therefore the magnetic tape comes into closely contact with the sliding surface of the head section. Accordingly, the magnetic spacing can be controlled at the minimum without depending on a protruding amount of the head section, an inclination angle of the sliding surface of the head section and an installation angle of the head section.
It is preferred that the multi-channel thin-film magnetic head further includes a closure fixed on the plurality of thin-film magnetic head elements of the head section.
It is also preferred that the sloped surface includes an inclined surface formed in an area of the sliding surface of the outrigger section near the head section, or formed over substantially whole area of the sliding surface of the outrigger section.
It is further preferred that the sliding surface of the head section is arranged at a position nearer to the magnetic tape than a head-section side edge of the sliding surface of the outrigger section.
It is further preferred that a head-section side edge of the sliding surface of the outrigger section is arranged at a position nearer to the magnetic tape than the sliding surface of the head section. In this case, more preferably, a height h′ is equal to or lower than a product of d×tan θ(h′≦d×tan θ), where θ is an inclination angle of the sloped surface with respect to the sliding surface of the head section, h′ is a height of the sliding surface of the head section with respect to the head-section side edge and d is a width of the slot section in the magnetic tape transport direction.
It is still further preferred that a width d of the slot section in the magnetic tape transport direction is larger than 0.1 mm and smaller than 2.0 mm (0.1 mm≦d≦2.0 mm).
It is further preferred that the plurality of thin-film magnetic head elements include a plurality of magnetoresistive effect (MR) read head elements and a plurality of inductive write head elements. In this case, more preferably, each of the plurality of MR read head elements comprises a giant magnetoresistive effect (GMR) read head element or a tunnel magnetoresistive effect (TMR) read head element.
According to the present invention, also, a multi-channel magnetic tape drive apparatus includes a pair of multi-channel thin-film magnetic heads, a magnetic tape facing to the pair of multi-channel thin-film magnetic heads, and a drive system for relatively moving the magnetic tape and the pair of multi-channel thin-film magnetic heads. Each of the pair of multi-channel thin-film magnetic heads includes a head section provided with a plurality of thin-film magnetic head elements and a sliding surface for a magnetic tape, a slot section running in a direction perpendicular to a magnetic tape transport direction, the slot section being arranged adjacent to the head section in the magnetic tape transport direction, and an outrigger section provided with a sliding surface for the magnetic tape and arranged to separate from the head section by the slot section in the magnetic tape transport direction. The sliding surface of the outrigger section includes a sloped surface with a height that reduces as approaching the head section.
The outrigger section is provided outside of the head section to separate from the head-section sliding surface by a slot section, and the sliding surface of the outrigger section is inclined toward the head section so that a height of the outrigger section reduces as approaching the head section. Therefore, the sliding surface of the outrigger section has a minus inclination angle with respect to that of the sliding surface of the head section. Thus, a negative pressure occurs at this sliding surface of the outrigger section to allow the magnetic tape closely contact with this sliding surface. As a result, because the magnetic tape is guided to a position that is lower than the sliding surface of the head section, this magnetic tape comes into contact with an edge of the sliding surface of the head section. Thus, negative pressure occurs due to masking effect at the edge of the sliding surface of the head section, and therefore the magnetic tape comes into closely contact with the sliding surface of the head section. Accordingly, the magnetic spacing can be controlled at the minimum without depending on a protruding amount of the head section, an inclination angle of the sliding surface of the head section and an installation angle of the head section.
It is preferred that each multi-channel thin-film magnetic head further includes a closure fixed on the plurality of thin-film magnetic head elements of the head section.
It is also preferred that, in each multi-channel thin-film magnetic head, the sloped surface includes an inclined surface formed in an area of the sliding surface of the outrigger section near the head section, or formed over substantially whole area of the sliding surface of the outrigger section.
It is further preferred that, in each multi-channel thin-film magnetic head, the sliding surface of the head section is arranged at a position nearer to the magnetic tape than a head-section side edge of the sliding surface of the outrigger section.
It is further preferred that, in each multi-channel thin-film magnetic head, a head-section side edge of the sliding surface of the outrigger section is arranged at a position nearer to the magnetic tape than the sliding surface of the head section. In this case, more preferably, a height h′ is equal to or lower than a product of d×tan θ(h′≦d×tan θ), where θ is an inclination angle of the sloped surface with respect to the sliding surface of the head section, h′ is a height of the sliding surface of the head section with respect to the head-section side edge and d is a width of the slot section in the magnetic tape transport direction.
It is still further preferred that, in each multi-channel thin-film magnetic head, a width d of the slot section in the magnetic tape transport direction is larger than 0.1 mm and smaller than 2.0 mm (0.1 mm≦d≦2.0 mm).
It is further preferred that, in each multi-channel thin-film magnetic head, the plurality of thin-film magnetic head elements include a plurality of MR read head elements and a plurality of inductive write head elements. In this case, more preferably, each of the plurality of MR read head elements comprises a GMR read head element or a TMR read head element.
Further objects and advantages of the present invention will be apparent from the following description of the preferred embodiments of the invention as illustrated in the accompanying drawings.
a to 7e are views schematically illustrating in comparison functions of the multi-channel thin film magnetic head according to the conventional art and the multi-channel thin film magnetic head according to the present invention;
a and 8b are views concretely illustrating relationships in height between a sliding surface in an outrigger section and a sliding surface in a head section in the multi-channel thin film magnetic head according to the present invention; and
In this embodiment, applied is the present invention to a LTO multi-channel magnetic tape drive apparatus of the fourth generation. Of course, the present invention is not limited to the multi-channel magnetic tape drive apparatus of LTO but is applicable to any kind of multi-channel magnetic tape drive apparatus.
In
As is known in the art, in LTO, write and read operations are performed to and from the multi-channel magnetic tape 12 of the half-inch width. The multi-channel thin film magnetic head 13 for this purpose is provided with magnetic read head elements of 16 channels, magnetic write head elements of 16 channels and magnetic servo head elements of 2 channels.
As shown in the figure, the multi-channel magnetic tape 12 has a plurality of tracks 12a. Also, the multi-channel thin-film magnetic head 13 has a first head section 13a, a second head section 13b, a first slot section 13c, a second slot section 13d, a first outrigger section 13e, a second outrigger section 13f and a frame 13g for supporting the both head sections and the both outrigger sections.
When performing write and read operations, the magnetic tape 12 moves in direction of arrow 14a or arrow 14b. The write and read operations of data signal with respect to the tracks 12a of the magnetic tape 12 are performed under the state where a tape bearing surface (TBS) 13h of the thin-film magnetic head 13 is in contact with the surface of the moving magnetic tape 12. The first head section 13a has a head-section sliding surface 13a1 (shown in
The first slot section 13c is arranged adjacent to the first head section 13a in the tape transport direction 14a. This first slot section 13c runs along a direction perpendicular to the tape transport direction 14a. The first outrigger section 13e is separated from the first head section 13a in the tape transport direction 14a by the first slot section 13c. This first outrigger section 13e has an outrigger-section sliding surface 13e1 (shown in
As partially shown in
As shown in
It should be noted that, in the section shown in
The plurality of GMR read head elements 51 are electrically connected to the plurality of terminal electrodes 55, respectively. Also, one ends of each GMR read head element 51 and each inductive write head element 52 are arranged to reach the TBS 13h and to come in contact with the relatively moving magnetic tape 12. Therefore, during writing operation, the inductive write head elements 52 apply signal magnetic fields to the respective tracks of the moving magnetic tape 12 to write data thereto, and during read operation, the GMR read head elements 51 receive signal magnetic fields from the respective tracks of the moving magnetic tape 12 to read data there from.
Each of the GMR read head elements 51 includes, as shown in
The GMR multi-layered structure 51a constitutes a magnetic sensitivity portion for detecting a signal magnetic field by utilizing the giant magnetoresistive effect. Instead of the GMR multi-layered structure 51a, an anisotropic magnetoresistive effect (AMR) structure utilizing anisotropic magnetoresistive effect or a tunnel magnetoresistive effect (TMR) multi-layered structure utilizing tunneling magnetoresistive effect may be used. In case of the GMR multi-layered structure, either current in plane (CIP) type GMR multi-layered structure or current perpendicular to plane (CPP) type GMR multi-layered structure may be adopted. The GMR multi-layered structure 51a will receive a signal magnetic field from each track 12a of the magnetic tape 12 with high sensitivity. In case that the GMR multi-layered structure 51a is the CPP-GMR multi-layered structure or that a TMR multi-layered structure is used instead of the GMR multi-layered structure, the lower shield layer 51b and the upper shield layer 51c serve as electrodes. On the other hand, in case that the GMR multi-layered structure 51a is the CIP-GMR multi-layered structure or that an AMR structure is used in stead of the GMR multi-layered structure, it is provided with insulation layers between the CIP-GMR multi-layered structure or the AMR structure and the lower and upper shield layers 51b and 51c, respectively and also it is provided with MR lead layers electrically connected to the CIP-GMR multi-layered structure or the AMR structure.
Each of the inductive write head elements 52 includes, as shown in
The lower magnetic pole layer 52a and the upper magnetic pole layer 52b function as a magnetic path of magnetic flux produced from the write coil layer 52d and also sandwich by their end sections the TBS side end section of the write gap layer 52c. The write operation is performed by means of leakage flux output from the sandwiched end section of the write gap layer 52c. In the figure, it is depicted that the write coil layer 52d has a single layer structure. However, in modifications, the write coil layer may have a multi-layered structure or a helical coil structure. Also, in modifications, a single common magnetic layer may serve as both the upper shield layer 51c of the GMR read head element 51 and the lower magnetic pole layer 52a of the inductive write head element 52 laminated on the GMR read head element 51.
The lower magnetic pole layer 52a is formed, by using for example a frame plating method or a sputtering method, from a single layer or multilayer of soft magnetic materials such as NiFe, CoFeNi, CoFe, FeN, FeZrN or CoZrTaCr, with a thickness of about 0.5-3.0 μm. The write gap layer 52c is formed, by using for example a sputtering method or a chemical vapor deposition (CVD) method, from a nonmagnetic insulating material such as Al2O3 (alumina), SiO2 (silicon dioxide), AlN (aluminum nitride) or DLC, with a thickness of about 0.01-0.05 μm. The write coil layer 52d is formed, by using for example a frame plating method or a sputtering method, from a conductive material such as Cu, with a thickness of about 0.5-5.0 μm. The coil insulation layer 52e is formed, by using for example a photolithography method, from a resin insulation material cured by heating, such as a novolac photoresist, with a thickness of about 0.7-7.0 μm. The upper magnetic pole layer 51c is formed, by using for example a frame plating method or a sputtering method, from a single layer or multilayer of soft magnetic materials such as NiFe, CoFeNi, CoFe, FeN, FeZrN or CoZrTaCr, with a thickness of about 0.5-3.0 μm. Also, the protection layer 53 is formed, by using for example a sputtering method or a CVD method, from a nonmagnetic insulating material such as Al2O3, SiO2, AlN or DLC.
Each of the terminal electrodes 55 includes a drawing electrode 55a, an electrode film 55b, a bump 55c and a pad 55d. The drawing electrodes 55a are electrically connected to lead lines from the GMR read head element 51 and from the inductive write head element 52. On each drawing electrode 55a, the electrode film 55b having conductivity is laminated, and the bump 55c is formed on the electrode film 55b by plating using this film 55b as an electrode for plating. The electrode film 55b and the bump 55c are made of a conductive material such as Cu. A thickness of the electrode film 55b is for example about 10-200 nm, and a thickness of the bump 55c is for example about 5-30 μm. A top end of the bump 55c is exposed from the top surface of the protection layer 53, and the pad 55d is laminated on this top end of the bump 55c.
As shown in
The aforementioned outrigger-section sliding surface 13e1 of the first outrigger section 13e has a sloping surface inclined toward the first head section 13a. More concretely, in this embodiment, the whole area of the outrigger-section sliding surface 13e1 of the first outrigger section 13e is configured by an inclined top surface with a height decreasing as approaching the first head section 13a. Whereas the head-section sliding surface 13a1 of the first head section 13a is a flat surface without being inclined. Similar to this, the aforementioned outrigger-section sliding surface 13f1 of the second outrigger section 13f has a sloping surface inclined toward the second head section 13b. More concretely, in this embodiment, the whole area of the outrigger-section sliding surface 13f1 of the second outrigger section 13f is configured by an inclined top surface with a height decreasing as approaching the second head section 13b. Whereas the head-section sliding surface 13b1 of the second head section 13b is a flat surface without being inclined.
In case that the magnetic tape 12 moves toward the opposite direction, the first head section 13a and the second head section 13b perform a reversed operations each other.
a to 7e schematically illustrate in comparison functions of the multi-channel thin film magnetic head according to the conventional art and the multi-channel thin film magnetic head according to the present invention.
a shows an example in the prior art, wherein inclination angles or taper angles of sliding surfaces of head sections 70a1 and 70a2 and protruding amounts of the head sections 70a1 and 70a2 are adjusted ideal. If these parameters are adjusted ideally as in this example, a pressure balance force 70a4 in a direction perpendicular to the sliding surface will be obtained resulting the magnetic spacing between head section 70a2 and the magnetic tape 70a3 becomes quite small. However, such ideal adjustment is extremely difficult.
b shows another example in the prior art, wherein protruding amounts of head sections 70b1 and 70b2 are smaller than the ideal values. In such case, inflow of air 70b5 occurs and thus pressure balance force 70b4 will lean from the direction perpendicular to the sliding surface. As a result, a magnetic spacing between a head section 70b2 and a magnetic tape 70b3 increases.
c shows further example in the prior art, wherein inclination angles of sliding surfaces of head sections 70c1 and 70c2 are larger than the ideal values. In such case, inflow of air 70c5 occurs and thus pressure balance force 70c4 will lean from the direction perpendicular to the sliding surface. As a result, a magnetic spacing between a head section 70c2 and a magnetic tape 70c3 increases.
d shows still further example in the prior art, wherein installation angles of head sections 70d1 and 70d2 deviate from ideal values. In such case, inflow of air 70d5 occurs and thus pressure balance force 70d4 will lean from the direction perpendicular to the sliding surface. As a result, a magnetic spacing between a head section 70d2 and a magnetic tape 70d3 increases.
e shows an example in the present invention, wherein outrigger sections 70e6 and 70e7 and slot sections 70e8 and 70e9 are provided. Because such outrigger sections 70e6 and 70e7 each having a sliding surface inclined toward a head section 70e1 or 70e2 are arranged outside the head sections 70e1 and 70e2 and also the slot sections 70e8 and 70e9 are arranged between the outrigger sections 70e6 and 70e7 and the head sections 70e1 and 70e2, a magnetic tape 70e3 is guided to a position that is lower than the sliding surface of the head section 70e2. Thus, even if protruding amounts of the head sections 70e1 and 70e2, inclination angles of the sliding surfaces of head sections 70e1 and 70e2, and installation angles of head sections 70e1 and 70e2 are not ideally adjusted, a pressure balance force 70e4 directs to a direction perpendicular to the sliding surface of the head section 70e2. As a result, a magnetic spacing between the head section 70e2 and the magnetic tape 70e3 can be kept at the minimum and therefore it is possible to come into closely contact the bi-directionally movable magnetic tape 70e3 with the head-section sliding surface to obtain excellent head performance.
a and 8b concretely illustrate relationships in height between the sliding surface in the outrigger section and the sliding surface in the head section in the multi-channel thin film magnetic head according to the present invention.
As shown in
Also, as shown in
Effect of providing the outrigger-section sliding surface sloped with an inclination angle toward the head-section sliding surface, in other words sloped to have a height decreasing as approaching the head section, was actually validated.
As shown in
Contrary to this, a multi-channel thin film magnetic head, in which an inclination angle θ of the outrigger-section sliding surface 92a is equal to 2 degrees (θ=2°, corresponding to the inclination angle of the present invention), an inclination angle θ′ of the head-section sliding surface 91a is equal to 2 degree (θ′=2°), and a width d of the slot section 93 is equal to 0.5 mm (d=0.5 mm) was prepared. Read-out outputs from read head elements of 15 channels in this multi-channel thin film magnetic head were measured, and then a standard deviation σ/average value Ave of the measured outputs was calculated. In this measurement, the obtained result was σ/Ave=0.08. The moving speed of the magnetic tape was 6.0 m/sec, the tensile force of the magnetic tape was 0.7 N, and the write frequency was 21.1 MHz.
It will be understood from the above validation that, by sloping the outrigger-section sliding surface toward the head section namely toward the opposite direction as the conventional outrigger section, with the inclination angle of 2 degrees, the read-out outputs from the magnetic head increase and fluctuation of the outputs decreases.
As aforementioned, according to this embodiment, the outrigger section is provided outside of the head section to separate from the head-section sliding surface by a slot section, and the outrigger-section sliding surface is inclined toward the head section so that a height of the outrigger section reduces as approaching the head section, that is, so that the outrigger-section sliding surface has a minus inclination angle with respect to that of the head-section sliding surface. Thus, a negative pressure occurs at the outrigger-section sliding surface to allow the magnetic tape closely contact with the outrigger-section sliding surface. As a result, because the magnetic tape is guided to a position that is lower than the head-section sliding surface, this magnetic tape comes into contact with an edge of the head-section sliding surface. Thus, negative pressure occurs due to masking effect at the edge of the head-section sliding surface, and therefore the magnetic tape comes into closely contact with the head-section sliding surface. When the magnetic tape moves reverse direction, since negative pressure occurs by inclination itself of the head-section sliding surface, the magnetic tape comes into closely contact with the head-section sliding surface.
Therefore, according to this embodiment, the magnetic spacing can be controlled at the minimum without depending on a protruding amount of the head section, an inclination angle of the head-section sliding surface and an installation angle of the head section. As a result, it is possible to increase read-out outputs of the magnetic head and to reduce fluctuation of the outputs.
In the aforementioned embodiment, the whole area of the outrigger-section sliding surface is formed as a sloped surface. However, in modifications, only a part near the head section may be formed as a sloped surface.
Many widely different embodiments of the present invention may be constructed without departing from the spirit and scope of the present invention. It should be understood that the present invention is not limited to the specific embodiments described in the specification, except as defined in the appended claims.