Magnetic disk drive

Abstract: A magnetic disk drive is described having a reduced size, using small disks (128) and an in-spindle construction for the disk driving means. The printed circuit board (115) is arranged within the disk drive enclosure (111,112), and advantageously has the spindle (120) of the disk driving means passing through a hole within it.

Description: 1. Field of the Invention The present invention relates to a magnetic disk drive that can be utilized as an external memory of a computer. More specifically, it relates to the arrangement of various components of a magnetic disk drive within a disk enclosure. Generally, a magnetic disk drive, having a number of magnetic disks utilized as recording media, has been in practical use in various regions including computer networks as one of the promising non-volatile memory devices. Furthermore, in recent years, the fabrication of a magnetic disk drive that satisfies the demand for a disk drive that is compatible, compact, inexpensive, has a large storage capacity, is light weight and has lower power consumption, has been required and has been in demand. To meet the above requirements, it is necessary for as many magnetic disks as possible to be assembled in a confined space, rather than increasing the surface density of recording media of magnetic disks by improving the characteristics of the magnetic head, magnetic medium per se, etc., so that mass storage can be attained without increasing costs for the development of the improved magnetic head. Alternatively, when same sheet of disks are assembled in the space, it is necessary for the size of the disk drive to be reduced as small as possible, so that effective space can be saved thereby promoting compactibility. When the magnetic disk drive is applied to a mobile-type computer, such as a portable lap-top personal computer, it also becomes necessary for the disk drive to withstand external impacts and external electromagnetic disturbance, and be lighter in weight and have a lower power consumption. In a known magnetic disk drive according to the prior art, typically, a number of disks are arranged rotatably at high speed in a laminated manner with equally divided spaces and on the respective surfaces of the magnetic layers, recording media are formed concentrically. Further, in the vicinity of these disks, positioners are mounted and movable in the direction of the tracks of the disks, respectively, and supporting members are attached to the above positioners, respectively. Further, on the respective ends of the above supporting members, the reproducing/recording elements, e.g., magnetic heads are fixed in close proximity to the respective surfaces of the disks, so that the former can perform read/write operations for the tracks of the disks. To be more specific, each of the above supporting members have an arm that is fixed on each of the positioners. The base end portion of each suspension element is fastened to the tip portion of each arm with screws. The above suspension element is formed by a bending process of an extremely thin stainless steel sheet. Further, on both sides of the suspension element, bent portions are formed respectively to ensure the stiffness of the above suspension element. Each magnetic head is attached to the tip portion of each suspension element, via a gimbal. In such a construction of a magnetic disk drive, in order to increase the maximum sheets of disks that can be assembled in a given place within a disk enclosure, it seems reasonable that the thickness of the arms of supporting members should be decreased so that the distance between the surfaces of adjoining disks become shorter. However, when the above distance is too short, the bent portions of adjoining suspension elements are likely to interface and come into contact with each other. Therefore, it is difficult for the distance between the surfaces of adjoining disks to be reduced below a fixed value. Furthermore, since the thickness of each magnetic head or any other portion of a supporting member other than the bent portion is also necessitated to some degree, it becomes more difficult for the distance between the surfaces of adjoining disks to be reduced to a value less than the limited value (for example, 3 mm). Consequently, when the dimensions of the disk drive is predetermined, a disadvantage occurs in that the sheets of disks cannot be increased much more than the limited value known in the prior art. On the contrary, when the number of sheets of disks assembled are predetermined, another disadvantage occurs in that the thickness of the disk drive cannot be reduced less than the limited value also known in the prior art. Furthermore, in the conventional 5 inch, 3.5 inch or 2.5 inch magnetic disk drive, a printed board of various controlling circuits is usually positioned separately from the disk enclosure including the magnetic head, disks, etc. Typically, the above printed board is fixed on the bottom surface of the disk enclosure, i.e., outside the disk enclosure (for example, see U. S. Pat. No. 5025335 (Frederick M. Stefansky)). Therefore, taking into account the thickness of the printed board, the height of the whole disk drive becomes more significant (for example, approximately 15 mm). Consequently, because of the thickness of the printed circuit board, it is further difficult to promote compactibility in the disk drive. Further, last year a 1.8 inch disk drive was introduced by Integral Peripherals Inc. The construction of the above disk drive is similar to that of other disk drives and the height of the former disk drive is also approximately 15 mm as a whole. Integral Peripherals Inc. is further emphasizing that a thinner disk drive, as thin as 10 mm, can be realized by locating a printed circuit board on the side of a disk enclosure. In this case, though the thickness of the disk drive can be reduced, a new problem occurs in that the area of the disk drive including the printed circuit board and the disk enclosure is enlarged more than usual. EP-A-0427490 describes a disk drive apparatus for use in a computer system such as lap top computer system. A low profile spin motor rotates a magnetic disk. The low profile spin motor uses high energy magnets made of a material which includes a rare earth, such as neodymium or samarium. A rotary actuator has a voice coil assembly of reduced height that is achieved by using the housing as a flux return path for magnetic field produced by the voice coil assembly. WO-A-91/02349 describes a disk drive which employs a closed-loop embedded servo tracking system to provide a large storage capacity relative to the area of storage medium available. The drive system of both disclosures is of the in-spindle type. The present invention is defined in the attached independent claim, to which reference should now be made. Further, preferred features may be found in the sub-claims appended thereto. It is noted that it is known per se from EP-A-0 419 022 that in a disk drive the inner circumferential portion of the rotor is connected to the outer circumferential portion of the bearings and the outer circumferential portion of the rotor is connected to the inner circumferential portion of the bearings. However, in EP-A-0 419 022 the disks are not mounted on the spindle at the same axial level as the disk driving means but on an axial extension thereof. A disk drive according to the present invention comprises disks, a disk driving means that forces the disks to rotate, magnetic heads for performing read/write operations of the surfaces of the recording media of the disks, arms supporting the magnetic heads, positioners that support the arms rotatably, bearings that are arranged to allow the positioners to rotate, a positioner driving means that forces the positioners to rotate to move the magnetic heads to a predetermined position on the surface of recording media of the disks, a base and cover that constitute a disk enclosure in combination with each other, and circuits for controlling at least the disk driving means, read/write operations of the magnetic heads. The circuits for controlling the disk driving means, the read/write operations of the magnetic heads, and the positioner driving means are mounted on a flexible printed circuit board contained in the inside of the disk enclosure. Consequently the height of the magnetic disk drive can be less than 10.5 mm. For a better understanding of the invention, and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings in which: Figs. 1 to 4 are views showing an example of a disk drive having the whole structure in which two disks are assembled in a disk enclosure according to the present invention. To be more specific, Fig. 1 is a front sectional view showing the whole structure; Fig. 2 is an exploded perspective view showing the main part of the structure; Fig. 3 is a partially assembled perspective view showing the main part of the structure and Fig. 4 is an enlarged perspective view showing the main part of the structure. As shown in these figures, a magnetic disk drive comprises the following components as a whole: two disks having a diameter of less than 1.8 inch, a disk driving means that forces the disks to rotate, four magnetic heads that perform read/write operations for the surfaces of recording media of the disks, arms that support the magnetic heads, positioners that support the arms rotatably, bearings that are arranged to allow the positioners to rotate, a positioner driving means that forces the positioners to rotate and make the magnetic heads move to a predetermined position on the surface of recording media of the fixed, a base and cover that constitute a disk enclosure in combination with each other; the disk enclosure protecting at least the disks, the disk driving means, the magnetic head, the arms, the positioners, the bearings and the positioner driving means, and circuits for controlling at least the disk driving means, read/write operations of the magnetic heads and the positioner driving means. In this case, the above circuits are composed of a flexible printed circuit board to be contained in the disk enclosure, and the height of the magnetic disk drive can be less than 10.5 mm. Further, the upper ends of shafts 113a, 113b are tightened to the cover 112 with screws. On one shaft 113a, two magnetic recording media (disks) 128 are supported and a spindle 120 is assembled. Further, on the other shaft 113b, positioners having actuators 130, magnetic heads 135 and arms 134 are supported. The above actuators 130 are adapted to move and maintain the magnetic heads 135 on the desired track of the disk 128. As shown in Figure 1, the printed circuit board 115 is arranged outside and around the spindle 120 to increase the utilisation of unoccupied space. 115 denotes a flexible printed circuit board. This printed circuit board 115 is adhered and fixed to the inner surface of the base 111 and cover 112 with a releasable adhesive, etc. On the printed circuit board 115, electronic circuit components 116, which is necessary for controlling the operation of whole disk drive (for example, servo control unit, DCM control unit, read/write unit, interface control unit and the like), are assembled. Further, the printed circuit board 115 is connected to a connector 117 that is supported by the base 111 and cover 112. Further, the connector 117 is connected to the receptacle of external electronic equipment (for example, a portable note-type computer) and therefore the magnetic disk drive shown in Figs. 1 to 4 operates as a memory device of the above external electronic equipment. Further, in these figures, a spindle 120 is provided. The disk driving means has an in-spindle construction in which the hub of a DCM (direct current motor), i.e., the outer diameter of the rotor yoke, is approximately equal to the inner diameter of the magnetic recording media 128. 121 denotes a stator having laminated structure silicon steel sheets. Stator 121 is fixed to the shaft 113a by means of adhesion. The numeral 122 denotes a coil of copper wire wound around the stator 121. Lead wires (not shown in Figs. 1 to 4 ) extending from the coil 122 are connected to the respectively corresponding terminal on the printed circuit board 115 by means of soldering and therefore the current for driving the spindle 120 is supplied to the coil 122, via the lead wires. Further, 123a denotes a lower bearing for magnetic recording media and 123b denotes a top bearing therefor. 124 denotes a spacer that maintains a constant gap between the lower bearing 123a and the top bearing 123b. The inner rings of the lower bearing 123a and the top bearing 123b are adhered and fixed to the shaft 113a. 125 denotes a hub of iron material. The inner peripheral portion of the hub 125 is adhered to the outer rings of the lower bearing 123a and the top bearing 123b. Further, in the position confronting the stator 121 in the hub 125, a magnet 126 is adhered to the stator 121, concentrically. Consequently, a magnetic circuit is formed by the stator 121, the hub 125 and the magnet 126. By supplying an alternating current to the coil 122, a driving force is induced in the above magnetic circuit to make the hub 125 rotate. Two sheets of magnetic recording medium 128 are held between a brim portion of the hub 125 and the spring ring 127, via a first spacer ring 129a and a second spacer ring 129b. By fastening the spring ring 127 to the hub 125 by compression by means of screws 114, a compression force is induced between the brim portion of the hub 125 and the spring ring 127, thereby firmly fixing two sheets of magnetic recording medium 128 and the first and second spacerring 129a, 129b. Further, the construction of the actuator 130 including a magnetic head 135 and arm 134 will be described in detail, particularly in Fig. 1. 131a denotes a lower bearing for an actuator and 131b denotes a top bearing therefor. 132 denotes a spacer that maintains a constant gap between the rear bearing 131b and the top bearing 131b. The inner rings of the rear bearing 131a and the top bearing 131b are fixed to the shaft 113b. 133 denotes a block of aluminium material. The inner peripheral portion of the block 133 is adhered to the outer rings of the rear bearing 131a and the top bearing 131b. Each rim portion 133a is arranged on one corresponding end of each block 133. On the respective surfaces of the rim portions 133a, four arms are adhered and fixed, respectively. The magnetic recording media 128 are adhered to one end of the arms 134, respectively. The magnetic head 135 confronts the respectively corresponding surfaces of the magnetic recording area. The coil 136 is fixed firmly on each side of the block 133 opposite each rim portion 133a by resin molding. 140 denotes a magnetic circuit that consists of a magnet 141 and a yoke of iron material 142. The above coil 136 is held in a magnetic air gap 143 of the magnetic circuit 140. The coil 136 is connected to the corresponding terminals on the printed circuit board 115, via an interconnecting means 116a, (for example, flexible printed circuit board) and the current is supplied to the coil 136. When the current flows through the coil 136 located in the magnetic air gap, a driving force is induced in the coil 136. Consequently, the actuator 130 moves rotationally around the shaft 113b. In read/write operations, a track position signal, indicating the present position of the magnetic head on the tracks, is issued from the magnetic head. In response to the above signal, the control circuit assembled on the printed circuit board controls the current that is supplied to the coil 136 and then moves and maintains the magnetic recording head 135 on the desired track of each magnetic recording medium 128. In this case, an integrated unitary magnetic head as described in the above-mentioned parent application is preferably used as a magnetic head, to realize smaller dimensions. However, a conventional magnetic head, such as a MIG magnetic head, can be used instead of the above unitary magnetic head. In such a construction, the lower and upper ends of a disk enclosure has usually has unoccupied space, except for the vicinity of the spindle and actuator. Therefore, the various circuits can be assembled on the above space and it becomes possible for the space in the disk enclosure to be utilized effectively. More concretely, the utilization of the unoccupied space in the disk enclosure can be realized by arranging a flexible printed circuit board in a position other than spindle, magnetic head, etc. and assembling the circuits on the above printed circuit. Conventionally, in 5 inch, 3.5 inch or 2.5 inch magnetic disk drives, a disk enclosure is made of aluminium to lighten said enclosure and the rigid printed circuit board is mounted on the bottom surface of a base of the disk enclosure. Furthermore, in a disk drive using disks having a diameter of less than 1.8 inch, the major part of various components of the disk drive is fabricated by press forming sheet metal. Therefore, an increase of the total weight can be minimized and the disk enclosure having an excellent shield effect and sufficient stiffness can be realized. Finally, in a disk drive with two disks according to the present example , a height of less than 10.5 mm and a storage capacity of greater than 120 MByte can be realized. In this case, the above disk drive can have the whole dimensions of approximately 85.6mm x 54.1mm x 10.4 mm (3.37 inch x 2.13 inch x 0.41 inch), similar to the conventional disk drive. Further, the above disk drive can have a total weight of less than 3 ounce (85g).

Claims: A magnetic disk drive comprising: a hollow spindle (120); disk driving means (121,122,125,126) enclosed within the hollow spindle that forces the disks to rotate; disks (128) mounted on the outer circumference of the hollow spindle at the same axial level as the disk driving means; bearings (123a,123b) that are arranged to allow the disks to rotate; magnetic heads (135) for performing read/write operations on the surfaces of the recording media of the disks; arms (134) supporting the magnetic heads; positioners (130) that support the arms rotatably; a positioner driving means (136,140) that forces the positioners (130) to rotate to move the magnetic heads (135) to a predetermined position on the surface of recording media of the disks (128); a base (111) and cover (112) that constitute a disk enclosure in combination with each other; the disk enclosure protecting at least the disks, the disk driving means, the magnetic heads, the arms, the positioners, the bearings and the positioner driving means; and circuits for controlling at least the disk driving means (121,122,125,126), the read/write operations of the magnetic heads (135) and the positioner driving means; characterised in that in the disk driving means (121,122,125,126) an inner circumferential portion of a rotor (125) is connected to an outer circumferential portion of said bearings and an outer circumferential portion of a stator (121) is connected to an inner circumferential portion of said bearings, and the circuits for controlling the disk driving means, the read/write operations of the magnetic heads, and the positioner driving means are mounted on a flexible printed circuit board contained in the inside of the disk enclosure. A magnetic disk drive according to claim 1, in which the disks are rotatably mounted around a spindle (120) and the printed circuit board (115) is arranged in the space that is not occupied by the spindle or positioner. A magnetic disk drive according to claim 2, in which the printed circuit board (115) has a hole passing through it, and is mounted so that the spindle passes through the hole. A magnetic disk drive as set forth in any preceding claim, wherein the disks (128) and magnetic heads (135) are constructed so that a perpendicular magnetic recording can be executed, and wherein the storage capacity of the magnetic disk drive is greater than 120 MByte. A magnetic disk drive as set forth in any preceding claim, wherein at least one of the spindles supporting the positioners is rotatable and a spindle (120) rotatably supporting the disks (128) is engaged directly with the base (111). A magnetic disk drive as set forth in any preceding claim, wherein the arms (134) are made of press-worked sheet metal. A magnetic disk drive as set forth in any preceding claim, wherein a motor hub (125) is provided as disk driving means, and the disks (128) are attached to the motor hub. A magnetic disk drive according to any preceding claim, in which there are two disks and four positions. A magnetic disk drive according to any preceding claim, in which the printed circuit is a flexible printed circuit board. A magnetic disk drive according to any preceding claim having a height of less than 10.5 mm, and preferably in which the disks have a diameter of less than 1.8 inch (4.57cm).

Inventors: ARIKAWA YOSHIHIRO, NISHIMURA KAHO, YAGI NORIO, ARIKAWA, YOSHIHIRO, NISHIMURA, KAHO, YAGI, NORIO
Applicants: FUJITSU LTD, FUJITSU LIMITED
Application year: 1992
Main classification: G11B5
IPC codes: G11B25, G11B19, G11B33