Floating magnetic head

Abstract: A floating magnetic head (1) characterized in that a spacer (11) made from a nonmagnetic substance and which is longer than a head core (9) is interposed between a slider (2) made from a magnetic substance and the head core (9), or a part of the slider (2) is made from a nonmagnetic substance and the head core (9) is secured thereon, and coils (8) are wound in a balancing manner around core portions (9a) and (9b) of the head core (9) respectively on the sides of air outflow end and air inflow end. The present invention allows to shield a noise of an external magnetic field by the slider (2) and to improve a recording accuracy because the slider (2) becomes independent of the head core (9) in terms of a magnetic circuit and a magnetic resistance of the slider (2) becomes smaller than that of the head core (9).

Description: BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a magnetic floating head used in a magnetic disk unit for computers or the like. Description of the Related Art Fig. 7 shows a composite type floating magnetic head 1 used in a magnetic disk unit for computers. The floating magnetic head 1 has a nearly rectangular slider 2 made from a nonmagnetic substance. Rails (floating surfaces) 3 for generating a floating force are provided on the upper portion, i.e. on the surface which faces a magnetic recording medium, of the slider 2. A groove 5 for winding coils which extends in the direction of width of the slider 2 is created on the side of air outflow ends 4, also called trailing ends 4, of the slider 2. A slit 6 which extends in the longitudinal direction of the rail 3 is created on a part of one rail 3 on the the air outflow end 4 side of the slider 2. A head core 9 having a recording and playback gap 7 on the upper part thereof and around which a coil 8 is wound is inserted to the inside of the slit 6. In the figure, the reference numeral 10 denote air inflow ends, also called leading ends, of the slider 2. JP-A-01 276421 discloses another floating magnetic head having a slider body composed of a non-magnetic material and having a cut channel formed on the side surface of the slider boy, the magnetic head core being fused and fixed by a transparent bonding glass in the channel. By the way, the tendency toward miniaturization and densification of record is increasing more and more lately in the field of a magnetic disk unit for computers. Then along the measures taken to accommodate with the aforementioned miniaturization and densification of record, such a problem is caused that an external magnetic field generated from a motor or the like for driving a magnetic disk may exert a bad influence on the magnetic head during reading/writing. Although it is necessary to shield the magnetic head from the noise caused by the external magnetic field to solve this problem, no measure has been taken heretofore in the prior art of floating magnetic heads to shield it from the aforementioned noise caused by the external magnetic field. Accordingly, it is an object of the present invention to solve the aforementioned problem by providing a floating magnetic head which can be shielded from the noise caused by an external magnetic field. SUMMARY OF THE INVENTION The aforementioned goal is achieved by a floating magnetic head according to claim 1. The above and other related objects and features of the present invention will be apparent from a reading of the following description of the disclosure found in the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view showing a floating magnetic head according to a first embodiment of the present invention; Fig. 2 is a perspective view showing a slider of the floating magnetic head shown in Fig. 1; Fig. 3 is a perspective view showing a state wherein a spacer is bonded with the slider; Fig. 4 is a perspective view showing a floating magnetic head according to a second embodiment of the present invention; Fig. 5 is a perspective view showing a floating magnetic head according to a third embodiment of the present invention; Fig. 6 is a perspective view showing a floating magnetic head according to a fourth embodiment of the present invention; and Fig. 7 is a perspective view showing one example of a prior art floating magnetic head. DETAILED DESCRIPTION OF PREFERRED EMBODIMENT Referring now to Figs. 1 through 6, a floating magnetic head of the present invention will be explained in detail. In those drawings, the same reference numerals are designated to the same members or same parts with those shown in Fig. 7 and explanation thereof will be omitted at times. Referring first to Figs. 1 through 3, a floating magnetic head according to a first embodiment will be explained. In the figures, the floating magnetic head 1 comprises in outline a nearly rectangular slider 2 made from a magnetic substance such as ferrite and having a floating surface that faces to a magnetic recording medium on one surface thereof, a head core 9 located and provided on a side portion 2a on the side of an air outflow end 4 of the slider 2 and having a recording and playback gap 7 and a spacer 11 made from a nonmagnetic substance such as ceramics and interposed between the slider 2 and the head core 9. A notch 12 for the spacer which is longer than the head core 9 is created on the side portion 2a on the side of air outflow end 4 of the slider 2. The spacer 11 which is longer than the head core 9 is stored in the notch 12. In the spacer 11, a spacer side notch 13 which joins with a groove 5 for winding coils created in the slider 2 is created. Coils 8 are wound around core portions 9a and 9b respectively on the air outflow end side and on the air inflow end side of the head core 9 in a manner positioning them around the groove 5 and notch 13. Both coils 8 are connected and wound in a balancing manner. The coils 8 are wound so that they do not contact with the slider 2. The construction of the floating magnetic head 1 will now be explained in detail along its manufacturing process. At first, the notch 12 for the spacer is created on the side portion 2a on the side of the air outflow end 4 of the slider 2 as shown in Fig. 2, the spacer 11 is bonded to this notch 12 by high fusion point glass as shown in Fig. 3 and then the groove 5 for winding coils is created on the air outflow end 4 side of one rail 3 of the slider 2 in a manner allowing to wind the coils 8. Next, the side portion 2a of the slider 2 and the spacer 11 are machined so that they share the same flat surface. At this time, the spacer 11 is machined so that its thickness lies between 0.050 mm and 0.075 mm. Then the head core 9 fabricated in a different process from that of the slider 2 is bonded with the spacer 11 bonded with the notch 12 of the slider 2 by low fusion point glass or the like. In the present embodiment, they were bonded by forming a glass thin film by a glass sputtering. Due to that, the glass thin film can be very thin. By the way, it is possible to create the notch 12 in the slider 2 beforehand and to fill melted glass to the notch 12 to use the filled glass also as a bond for bonding the spacer 11 with the head core 9. After that, lapping is carried out to the rails 3 so that a depth of the recording and playback gap 7 of the head core 9 is adjusted to a predetermined size and tape lapping is carried out on the floating surface to chamfer edges 15 of the rails of the slider 2. Then an inclined face 14 is created by diagonally grinding the head core 9 from the side not bonded with the slider 2 to adjust a track width Tw of the head core 9 appearing to the rail 3 to a predetermined size. By the way, an area of the nonmagnetic spacer 11 and head core 9 appearing to the rail 3 is very small as compare to that of the magnetic slider 2 appearing to the rail 3. In the floating magnetic head 1 constructed as described above, the slider 2 is independent from the head core 9 in terms of a magnetic circuit because the nonmagnetic spacer 11 is interposed between the slider 2 and the head core 9. Further, a magnetic resistance of the slider 2 is small as compared to that of the head core 9 because the slider 2 is made from a magnetic substance. Due to that, a noise from an external magnetic field is shielded by the slider 2 and a recording accuracy of the head can be improved. Furthermore, because the coils 8 are wound to the head core 9 in a balancing manner, the external magnetic field can be canceled further. Because the area appearing to the rail 3 is mostly that of the slider 2 due to the fact that the area of the nonmagnetic spacer 11 and head core 9 appearing to the rail 3 is very small as compared to that of the magnetic slider 2 appearing to the rail 3 and because the edge 15 of the slider 2 appearing to the rail 3 is chamfered, the magnetic recording medium will not be damaged by the edge 15 even when it is operated by a CSS (Contact Start Stop) system and thereby the resistance to CSS can be improved. Further, because the notch 12 for the spacer is created on the slider 2 and the spacer 11 is arranged to be stored in the notch 12, the spacer 11 can be provided without increasing the size of the unit. Fig. 4 is a perspective view showing the floating magnetic head 1 according to a second embodiment of the present invention. In the floating magnetic head 1 of the second embodiment, a spacer 11 having a same length with that of the side portion 2a of the slider 2 is bonded with the side portion 2a of the slider 2 and the head core 9 is bonded with this spacer 11. At this time, the spacer 11 is fabricated so that its thickness lies between 0.050 mm and 0.075 mm. This floating magnetic head 1 can shield the noise of the external magnetic field by the magnetic slider 2 and because the coil 8 is wound around the head core 9 in the balancing manner, can cancel the external magnetic field further similarly to the floating magnetic head 1 in the first embodiment described above. Fig. 5 is a perspective view showing the floating magnetic head 1 according to a third embodiment of the present invention. Whereas the slider 2 of the floating magnetic head 1 of the first embodiment has the notch 12 for the spacer, no notch is created on the slider 2 in the floating magnetic head 1 of the third embodiment. It is constructed by bonding the spacer 11 with the head core 9 beforehand and then by bonding the spacer 11 with which the head core 9 has been bonded with the side portion 2a of the slider 2. The spacer 11 is fabricated so that its thickness lies between 0.050 mm and 0.075 mm at this time. This floating magnetic head 1 can shield the noise of the external magnetic field by the magnetic slider 2 and because the coil 8 is wound around the head core 9 in the balancing manner, can cancel the external magnetic field further similarly to the floating magnetic head 1 in the first embodiment described above. Furthermore, because the step for creating a notch on the side portion 2a of the slider 2 is eliminated, the production manday can be reduced to that degree. Fig. 6 is a perspective view showing the floating magnetic head 1 according to a fourth embodiment of the present invention. In the figure, the floating magnetic head 1 comprises a nearly rectangular slider 2 and a head core 9 having a recording and playback gap 7. The head core 9 is bonded with the side portion 2a of the slider 2 on the side of the air outflow end 4. The slider 2 is composed of a first slider block 12 made from a nonmagnetic substance such as ceramics provided in correspondence with a portion 11' bonded with the head core 9 and a second slider block 13 made from a magnetic substance such as ferrite provided in correspondence with the other portion excepting the portion 11' bonded with the head core 9. The construction of this floating magnetic head 1 will now be explained in detail along its manufacturing process. At first, the first slider block 12 and the second slider block 13 are bonded by high fusion point glass to joint them. Then after creating the rails 3 which are to become the floating surface, the aforementioned bonded first and second slider blocks 12 and 13 are cut into a desired slider width to obtain the slider 2. Then, the groove 5 which allows to wind the coil 8 around the core portions 9a and 9b of the head core 9 on the side of air outflow end is created on the side of the air outflow end 4 of one rail 3 of the slider 2. Next the head core 9 fabricated in a different process from that of the slider 2 is bonded with the side portion 2a of the slider 2 by low fusion point glass or the like. In the present embodiment, they were bonded by forming a glass thin film by glass sputtering. Due to that, the glass thin film can be very thin. By the way, a distance between the recording and playback gap 7 and the second slider block 13 is separated so that it becomes greater than a width of the recording and playback gap 7 by more than 10 to 20 times by adjusting and setting the size of the first slider block 12 and the bonding position of the head core 9. After that, lapping is carried out on the rails 3 so that a depth of the recording and playback gap 7 of the head core 9 is adjusted to a predetermined size and tape lapping is carried out on the floating surface to chamfer edges 15 of the rails 3 of the slider 2. Then an inclined face 14 is created by diagonally grinding the head core 9 from the side not bonded with the slider 2 to adjust a track width Tw of the head core 9 appearing to the rail 3 to a predetermined size (7 micron in the present embodiment). Such machining of the track width Tw of the head core 9 may be carried out using an etching technology such as ion milling. By the way, because the head core 9 is chamfered from the both sides of air inflow end and air outflow end and is ground diagonally on the side of the floating surface to the size of the track width Tw, the portion of the head core 9 which appears to the rail 3 is only a small portion of the track width Tw. In the floating magnetic head 1 constructed as described above, a magnetic resistance of the slider 2 is small as compare to that of the head core 9 because the most of the slider 2, i.e. the second slider block 13, is made from a magnetic substance. Due to that, the noise from the external magnetic field is shielded by the magnetic second slider block 13. Furthermore, because the recording and playback gap 7 and the second slider block 13 are separated by the distance 10 to 20 times of the width of the recording and playback gap 7, a magnetic field generated by the recording and playback gap 7 during recording is not influenced by the second slider block 13. A size of the first slider block 12 made from a non-magnetic substance is made to be larger than the head core 9 so that the core portion 9b of the head core 9 on the side of air inflow end does not contact with the magnetic second slider block 13. Because an area which appears to the rail 3 is mostly that of the second slider block 13 due to the fact that the area of the first slider block 12 and head core 9 appearing to the rail 3 is small as compare to that of the second slider block 13 appearing to the rail 3 and because the edge 15 of the slider 2 appearing to the rail 3 is chamfered, the magnetic recording medium will not be damaged by the edge 15 even when it is operated by a CSS (Contact Start Stop) system and thereby the resistance to CSS can be improved. Furthermore, the groove 5 for winding coils is created on the slider 2 on the side of the air outflow end 4 of one rail 3 in a manner allowing to wind the coils 8 around core portions 9a and 9b respectively on the air outflow end side and on the air inflow end side of the head core 9. The both coils 8 are connected and are wound in a balancing manner. By constructing the floating magnetic head as described above, the slider can be independent of the head core in terms of a magnetic circuit because the nonmagnetic spacer is interposed between the slider and the head core, and a magnetic resistance of the slider can be small as compare to that of the head core because the slider is made from a magnetic substance. The coil can be wound in a balancing manner around the core portions of the head core 9 respectively on the sides of the air outflow end and air inflow end in the state that the spacer is interposed between the slider and the head core. The spacer can be also interposed between the slider and the head core in a manner storing the spacer in a notch by creating the notch for storing the spacer on the slider. Further, because the portion of the slider bonded with the head core is made from a nonmagnetic substance and the other portion of the slider excepting that portion is made from a magnetic substance and because the later portion is made large, the most of the slider is dominated by the magnetic substance and its magnetic resistance can be small as compare to that of the head core.

Claims: A floating magnetic head (1) comprising: a substantially rectangular slider (2) having leading (10) and trailing ends (4), and provided with a notch (12) which is formed on a side portion on the slider; a groove (5) being formed on an outside of the slider (2) ; rails (3) mounted on a surface of the slider (2) which is facing a magnetic recording medium to produce a floating force; characterized in that the groove gradually increases in depth along a longitudinal direction of the slider and forms an opening at the trailing end (4), that said slider (2) is made of a magnetic substance, that a spacer (11) made of non-magnetic substance is located in the notch (12), which is external to the slider rail (3), that a head core (9) is bonded to an outside surface of the spacer (11) and has first and second legs (9b, 9a), the second leg (9a) being located at the trailing end (4) of the slider (2) without protruding from the trailing end such that the first leg (9b) is located between the second leg (9a) and the leading end (10) of the slider, and that the length of the spacer (11) measured in the longitudinal direction of the slider (2) is greater than the length of the head core (9) measured in the longitudinal direction of the slider and that the length of the groove (5) measured in the longitudinal direction of the slider is greater than the length of the head core (9) measured in the longitudinal direction of the slider. The floating magnetic head according to claim 1, wherein the length of the spacer (11) measured in the longitudinal direction of the slider is equal to the length of the slider (2) measured in the longitudinal direction of the slider. The floating magnetic head according to claims 1 to 2, wherein the head core (9) has an inclined face (14) on a side opposite to the bonded side. The floating magnetic head according to claims 1 to 3, wherein coils (8) are wound around legs (9a, 9b) of the head core (9) in a balancing manner.

Inventors: EGAWA MOTOJI, FUJITA TETSUJI, SANO AKINOBU, TAKAYANAGI KAZUTOSHI, EGAWA, MOTOJI, FUJITA, TETSUJI, SANO, AKINOBU, TAKAYANAGI, KAZUTOSHI, EGAWA, MOTOJI, C/O MINEBEA CO., LTD., FUJITA, TETSUJI, C/O MINEBEA CO., LTD., SANO, AKINOBU, C/O MINEBEA CO., LTD., Takayanagi, Kazutoshi, c/o Minebea Co., Ltd.
Applicants: MINEBEA KK, MINEBEA CO.,LTD.
Application year: 1993
Main classification: G11B5
IPC codes: G11B5