KR0159254B1 - Disc device - Google Patents

Abstract

The present invention provides a small card type disk drive used as an external memory of a computer system such as a magnetic disk. In general, when used in personal computers, magnetic disk drives and IC memory cards require high durability against external magnetic fields as well as shock. Therefore, it is necessary to retract the magnetic head to a parking zone at an arbitrary position in the data area on the inner surface of the disk when the disk is stopped. The present invention provides a evacuation magnet (85) in the outer fringe of the rotary actuator 29 provided in the housing (21) in order to evacuate the magnetic head to a predetermined position and the evacuation yoke (near the evacuation magnet) 87) can be provided, but configured to have a predetermined gap with the retracted magnet, thereby achieving a magnetic disk drive having small size, light weight, low power consumption and high durability against mechanical shock.

Description

[Name of invention]

Disk drive

[Technical Field]

The present invention relates to a disk drive that can be used as an external memory of a computer system such as a magnetic disk or a magneto-optical disk. In particular, it relates to the overall structure of a disk drive having the structure of a credit card type housing, its circuit assembly and each of the various mechanical components within said housing.

[Background]

Generally, a disk drive having at least one magnetic disk used for a recording medium, for example, a magnetic disk drive is substantially used in various areas including a computer system as a persistent memory device. Moreover, in recent years, improvements in the technical aspects of magnetic disk drives have been realized, such as increasing the magnetic recording density of magnetic disks, and essentially reducing the size of magnetic disk drives. On the other hand, due to the recent rapid development of microelectronic technology, systems and the like have been miniaturized, reduced in weight, and low in power consumption, as an example of a portable personal computer.

Although miniaturization of magnetic disk drive technology has recently been advanced as described above, even if magnetic disks having a diameter of 2.5 are used, the dimensions are still large and the weight is still high. Therefore, it is difficult to apply current magnetic disk drives to such portable personal computers that are compact, light weight and require low power consumption. Magnetic disk drives using magnetic disks with a diameter of 1.89 to meet these requirements have recently been publicly announced. This magnetic disk drive has certainly smaller dimensions than a magnetic disk drive with a 2.5 diameter. However, in such a magnetic disk drive composed of a magnetic disk having a 1.89 diameter, the reduction (miniaturization) of the magnetic disk drive has been attempted using the prior art without any improvement. Thus, there arises a problem that the dimensions of the magnetic disk drive, in particular the thickness or height, are still very large for a disk drive actually used as a portable device. It is well known that these days the minimum limit for its thickness is as large as 10 mm. Moreover, even if the disk drive is applied to a portable device, another problem arises that the magnetic disk drive does not have sufficient durability against mechanical shock caused by external factors such as falling of the portable device.

In addition, a single disk file subsystem of modules is disclosed in US Pat. Nos. 4639863 and 4860194, in which the expanded printed circuit board is directly attached to the housing side including the head and disk assembly to achieve thinner dimensions. Moreover, even if the thickness of the disk drive is sufficiently reduced, a new problem arises that the housing and the area of the disk drive including the printed circuit board are expanded.

Even in view of these conditions, in existing portable personal computers or the like currently used, integrated circuit memory cards are temporarily used in addition to magnetic disks because they can secure necessary dimensions and weights. The specifications of this IC memory card, which are specified as the thickness or height of the card at 5mm or 3.3mm, have recently been standardized (standard specifications of JEIDA (Japan Electronic Industry Development Association) and PCMCIA (International Association of Personal Computer Memory Cards)). Cards that meet the specification are thin enough and light enough. Thus, the card is suitable for application in portable personal computers in terms of dimensions and weight.

However, the IC memory card currently has two important problems as follows.

First, computer systems using IC memory cards are extremely expensive. Specifically, its price per megabyte is hundreds of times higher than a computer system using a flexible disk drive and tens of thousands of yen / MByte higher than that of a hard disk drive (i.e. magnetic disk drive). .

Secondly, the total storage capacity of the computer system using the IC memory card is not sufficient to meet the current needs of the user. Nowadays, IC memory cards having a storage capacity of approximately 1 megabyte are mainly used. The storage capacity of the IC memory card may increase to a number of several megabytes to ten megabytes in the future. On the other hand, in the current ideal portable personal computer, a memory system having 40 megabytes or more is substantially needed. Therefore, a computer system using the IC memory card cannot practically satisfy the current desire for storage capacity. Moreover, it is expected that the memory capacity required by the user in the near future will increase gradually. Therefore, even considering the development of IC memory technology, it is difficult to keep up with the required storage capacity of the IC memory card.

As described above, if the magnetic disk drive according to the prior art is used in a portable personal computer, it is not sufficient for the dimension, weight, power consumption and durability against mechanical shock even if it is sufficient for cost and storage capacity. On the contrary, even though the IC memory card used in the portable personal computer is enough for the dimension, weight, power consumption and durability against mechanical shock, the price of the IC memory card is very expensive, and its capacity is satisfactory for the user. not. Therefore, there is a strong demand for a memory device having the advantages of a magnetic disk drive and an IC memory card to realize a suitable portable personal computer.

As a method for overcoming the above-mentioned drawbacks, the use of the III type specification of PCMCI is effectively considered. In the III form of this PCMCI, the same dimensions as the form I and form II are defined for the plane direction, while the thickness dimension allows a maximum of 10.5 mm. If one connector is provided that matches Form III of PCMCI, a cord with a thickness of 10.5 mm may be inserted into a slot of a different type of thickness of Form I and Form II placed vertically. Can be.

As mentioned above, if the dimension of the thickness dimension is defined as 10.5 mm, the disk drive in the form of a card can be realized using the prior art without improvement. In fact, devices with a thickness of 10.5 mm have already been announced. However, the size reduction of the device is inevitable in personal computers, in particular notebook type personal computers, and therefore the structure in which the two slots are arranged in the vertical direction is a disadvantage in terms of size reduction. On the other hand, in a palm top type personal computer, only one slot is provided for each personal computer. In other words, it is currently difficult for an IC memory card to be replaced by a magnetic disk drive and used for memory devices in all fields. Therefore, there is a strong demand for realizing a disk drive having an external dimension conforming to Form I or Form II, that is, a magnetic disk drive having a thickness of 5 mm or less.

[Initiation of invention]

It is therefore an object of the present invention to provide a magnetic disk drive having a low cost and sufficient storage capacity which simultaneously possesses the advantages of an IC memory card of small size, light weight, low power consumption and sufficient durability against mechanical shock.

Another object of the present invention is to provide a magnetic disk drive having the same thickness as an IC memory card, for example, 5 mm, lighter than 70 g, durability against mechanical shock of 200 G or more, and resistance to external magnetic fields of 1 K Gauss or more.

Disc drive according to the present invention in order to achieve the above object, at least one disk for storing information, a disk drive means for rotating the disk, a head component for performing a read / write operation on the disk, And electronic circuit elements. In addition, at least one connector connected to the electronic circuit element is fixed outside the housing.

In addition, the electronic circuit device may be configured to provide an interface circuit allowing connection with an external host system, operation of a read / write circuit for receiving a read signal from the head assembly and providing a write signal to the head assembly, the magnetic disk and the head assembly. And a control circuit that receives the control signal from the host system via the interface circuit and provides the control signal to the read / write circuit and the servo circuit.

Moreover, the head assembly includes a magnetic head for performing a read / write operation corresponding to a read / write operation of information at a predetermined position on a magnetic disk, a support spring mechanism for supporting the magnetic head, and an arm for supporting a spring mechanism. And a rotary actuator which causes the arm to rotate in one direction and causes the magnetic head to move to a predetermined position on the magnetic disk.

Moreover, the housing has a bottom portion of the substrate and a top portion of the lid, and the electronic components constituting the electronic circuit element are formed on at least one printed circuit board positioned along both the inner wall surface of the substrate and the lid, or along one of the inner wall surfaces, respectively. Is assembled on. In detail, the printed circuit board is composed of a flexible printed circuit board. Alternatively, a printed circuit board in which both the substrate and the cover are made of metal and based on metal is also used.

Moreover, preferably the disc drive according to the invention has an external dimension in the plane direction of approximately 85.6 mm x 54 mm and has a thickness of less than 8 mm, typically 5 mm.

Further, a plurality of insertion guide portions are preferably provided in predetermined portions on each side having a longer dimension of the housing, which allows the housing to be inserted into the slot of the host device such that the disk drive is in operation.

Also, preferably only one connector is attached to one side part with a shorter dimension of the housing. Moreover, the connector is disposed approximately in the center position with respect to the thickness direction of the housing and is attached to either side having the shorter dimension of the housing at the opposite position of the head assembly across the magnetic disk.

Further, the substrate and the lid of the housing preferably each have a joining flange extending outward except a portion in which the connector is disposed at its outer periphery, the housing being formed by joining the joining flanges to each other. In this case, the substrate and the cover are made of a metal containing iron, a metal containing aluminum, or a resin material. Moreover, the defective engagement flange is covered with at least one frame designed to be provided as an insertion guide rail, a closure for sealing the interior of the housing, or a cushioning means to protect the housing from mechanical shock.

In addition, the disk drive means preferably comprise a spindle motor disposed on the inner side of the disk so that the disk can rotate. Moreover, the spindle motor has a first fixed shaft which is fixed at a predetermined position in the housing to rotatably support the disk, and has a pair of first bearing means which are respectively fixed on the upper side and the lower side of the first fixed shaft to hold the disk. Have

The head assembly includes at least one magnetic head for performing a read / write operation corresponding to a read / write operation of information on either surface of the upper and lower surfaces of the magnetic disk, at least one arm supporting the magnetic head, And an actuator that rotates in either direction and moves the magnetic head to a predetermined track on the magnetic disk.

Moreover, the head assembly has a rotary actuator that rotates the arm in either direction and moves the head to a predetermined track on the magnetic disk, and has a second fixed shaft fixed at a predetermined position in the housing, respectively on the upper and lower sides of the second fixed shaft. It has a pair of second bearing means which are fixed. In addition, the first and second fixed shafts are configured to be fixed to the substrate by assembling them to the substrate.

Preferably, the first fixed shaft and the second fixed shaft each have a flange portion on one part of the first fixed shaft and the second fixed shaft, and the flange portion of the first fixed shaft has a diameter approximately equal to or greater than the average length between the pair of first bearing means. And the flange portion of the second fixed shaft has a diameter approximately equal to or greater than the average length between the pair of second bearing means.

Also preferably, the first fixed shaft of the disk and the second fixed shaft of the actuator are firmly coupled with the lid in the thickness direction of the housing. Specifically, one end of the fixed shaft of the disk and the fixed shaft of the actuator is fixed to the lid by spot welding or bonding.

Also preferably the spindle motor is rotated through the bearing means having a fixed shaft for fixing the spindle motor by itself at a predetermined position in the housing, a pair of bearing means fixed around the fixed shaft, and an outer portion engaged with the central hole of the magnetic disk. A spindle hub possibly having an inner portion mounted to the first fixed shaft, at least one rotating magnet fixed to the spindle hub, and at least one stator coil fixed to the substrate. In this case, the rotor magnet is disposed between the position of the outer periphery of the bearing means and the position of the inner diameter of the magnetic disk with respect to the radial direction of the rotor magnet.

Specifically, the spindle motor is an outer ring rotary motor, and the rotating magnet has a thickness larger than the average distance between the center of each of the pair of bearing means on the upper and lower sides and the magnetic disk, and the rotating magnet and The pair of bearing means is disposed at approximately the same position with respect to the thickness direction of the housing.

Alternatively, the spindle motor is a flat motor having an axial gap in which the magnetic gap is formed in the axial direction of the fixed shaft of the spindle, the magnetic disk is coupled to the outer periphery of the rotating magnet, and the inner periphery of the rotating magnet is provided with bearing means. It is rotatably supported by the fixed shaft of the spindle via it, and the rotating magnet is also assembled such that it serves as the spindle hub.

In both types of spindle motors, the magnetic disk is preferably fixed to the spindle hub by adhesion.

More preferably, the disc drive according to the present invention also has a evacuated magnet provided in the outer fringe of the actuator for causing the magnetic head to be evacuated, and an evacuated yoke disposed around the evacuated magnet and disposed with a gap with the evacuated magnet. It consists of.

More specifically, the thickness of the gap changes in the direction of displacement of the magnetic head to retract the magnetic head to a predetermined position. Typically, the thickness g of the gap is approximately changed in relation to approximately 1 / (X + Xo) with respect to the displacement value X of the magnetic head.

Also, the areas of the portions where the retracted magnets and the retracted yokes are included in the spaces therebetween are changed in the displacement direction of the magnetic heads in order for the magnetic heads to be retracted to predetermined positions.

More preferably, the disk drive according to the present invention consists of a head assembly having one magnetic disk of 4.8 cm (1.89) or less, two magnetic heads for performing read / write operations, and furthermore connected to electronic circuit elements outside the housing. Consisting of one connector, having an external dimension in a plane direction of approximately 85.6 mm x 54 mm. In this structure, the magnetic disk and the two magnetic heads are configured such that vertical magnetic recording can be performed. Typically each two magnetic heads are a single magnetic head with a body composed of a flexible thin plate. In addition, the magnetic disk and the two magnetic heads are configured such that horizontal magnetic recording can be performed, and each of the two magnetic heads includes a head slider having a predetermined flying height.

[Brief Description of Drawings]

1 and 2 show an example of a disk drive structure according to the prior art.

3, 4, 5, 6 and 7 show a preferred embodiment of the disc drive structure according to the present invention.

8 and 9 illustrate one preferred embodiment of a head retraction structure for the disc drive of the present invention.

FIG. 10 is a graph for explaining the relationship between the gap value of FIG. 9 and the displacement of the magnetic head. FIG.

11 is an enlarged perspective view of FIG.

12 is a model of rotation using a magnetic force to explain the principle of the head evacuation mechanism in the disk drive according to the present invention.

Fig. 13 is a graph showing the actual measurement results of torque in the head retraction mechanism in the form of gap change.

14 shows an example of the head evacuation mechanism in the form of area change.

Fig. 15 shows another example of the head evacuation mechanism in the disc drive according to the present invention.

[Description of Preferred Embodiment]

Prior to describing an embodiment of the present invention, the prior art and its disadvantages will be described with reference to the associated drawings.

1 and 2 show an example of a disk drive structure according to the prior art. More specifically, FIG. 1 is a front view showing the overall structure of a disk drive according to the prior art, and FIG. 2 is an illustrative view showing the circuit assembly and the mechanical assembly of the disk drive separately in FIG.

In this case, the magnetic disk drive 1 has two housings, an inner housing 6 and an outer housing 7. As shown in FIGS. 1 and 2, the magnetic disk 2, the spindle motor 3, the magnetic head mechanism 4, the head IC5 constituting the amplifying circuit 5a, and the like are included in the inner housing 6 surrounded by the outer housing 7. As shown in FIG. Furthermore, in the space between the inner housing 6 and the outer housing 7, IC8 constituting the read / write circuit 8a, IC9 constituting the control circuit 8b, IC10 constituting the position circuit 8c and IC10 'constituting the interface circuit 8d are provided. Combined. In addition, a connector 7 'is attached to the outer housing 7.

This magnetic disk drive 1 is stored in a predetermined location and, if necessary, is connected to an external host system such as a host computer (not shown) using the connector 7 'and performed. Furthermore, information can be read (reproduced) from the magnetic disk 2 using the read / write circuit 8a and recorded on the magnetic disk 2. More specifically, in the above circuit configuration, the control signal Sc and the address signal Sa are transmitted from the host computer to the interface circuit 8d via the connector 7 '. Further, the control signal Sc is input to the control circuit 8b, and the state signal Ss indicating the current state of the magnetic disk drive 1 is oscillated from the control circuit 8b to the interface circuit 8d. The interface circuit 8d is also coupled to the positional circuit 8c for determining the position of the magnetic head mechanism 4 on the magnetic disk 2 in accordance with the command of the host computer. The information of the position read by the magnetic head mechanism 4 is transmitted back to the position circuit 8c as the position signal Sp via the amplifying circuit 5a so that accurate positioning can be performed by the subcircuit. Moreover, power is supplied to all of the above circuits along with other merged circuits.

In the above-mentioned prior art, the inner and outer housings 6 and 7 have an inner housing containing disk drive yaw mechanical components and form a dual structure with an outer housing 7 surrounding the inner housing and mainly comprising electronic circuit elements. . Due to this dual structure, the lower limit of the thickness H ₁ (FIG. 1) of the outer housing, that is, the height dimension of the disc dry 1, is likely to be limited to an arbitrary minimum value. Therefore, according to the prior art as shown in FIGS. 1 and 2, it is difficult to realize a disk drive having an overall dimension that matches the dimensions of the IC memory card and having a thickness smaller than that of the IC memory card. Therefore, the external dimensions of the disc drive, in particular the total thickness, can be significantly reduced by providing a housing of a single structure.

3, 4, 5, 6 and 7 show a preferred embodiment of the structure of the disc drive according to the present invention. More specifically, FIG. 3 is a perspective view showing the external shape of the magnetic disk drive and its dimensions. 4 is a perspective view partially showing the structure in the housing. FIG. 5 is an illustrative view showing the mechanical assembly and the circuit assembly respectively described in FIG. 6 is an enlarged perspective view showing the structure of FIG. 4 in more detail. 7 is a front cross-sectional view of FIG.

In a preferred embodiment of the present invention, as described in these figures, the magnetic disk drive 20 consists of a single rectangular housing 21 consisting of a substrate on the bottom and a lid on the top. Moreover, the housing 21 has an external dimension in the plane direction of approximately 85.6 mm x 54 mm and has a thickness of 8 mm or less, typically 5 mm or 3.3 mm. That is, the magnetic disk drive 20 may have the same size as that of the IC memory card currently used in Form II of PCMCIA.

In this case, one magnetic disk 24 having a diameter of 48 mm or 1.89 for storing information, a disk drive means 15 for rotating the magnetic disk, and a magnetic disk, unlike in the prior art as shown in FIGS. 1 and 2 An electronic circuit element composed of a head assembly which performs a read / write operation with respect to 24 and an electronic component 70 is included in a sealed space in the one housing 21.

Furthermore, the disc drive means 15 is a fixed shaft 25 of the spindle fixed to a predetermined position in the housing 21 for rotatably supporting the spindle motor 26 and the magnetic disk 24 disposed inside the magnetic disk 24 so that the magnetic disk can rotate. Has

In addition, the head assembly includes at least one magnetic head 27 and at least one magnetic head 27 for performing a read / write operation corresponding to a read / write operation of information on either surface of the upper and lower surfaces of the magnetic disk 24. And an actuator 29 which moves the magnetic head to a predetermined track on the magnetic disk 24 and rotates the arm 28 in either direction.

Moreover, in another preferred embodiment, a head with a small pressure load is used as the magnetic head. For example, the contact type magnetic head disclosed in Unexamined Japanese Patent Application Laid-Open No. 3-178017 can be used as the magnetic head 27, and an extremely small load of tens of mg can be used. On the other hand, in the flying type head as shown in FIGS. 4 to 7, it is possible to use a head having a relatively small load of several hundred mg. Moreover, by employing a negative pressure head slider and a load / unload mechanism in the disc drive according to the present invention, the frictional force of the head generated when the spindle motor is actuated can be substantially ignored. . Because of this advantage, a spindle motor running at a relatively low voltage can be realized. In addition, the electronic circuit element can operate the interface circuit 39 which allows connection with an external host computer, the read / write circuit 36 which receives the read signal from the head assembly and provides the head assembly, the write signal, the magnetic disk 24 and the head assembly. A servo circuit composed of an amplification circuit (head IC) 35 and a position circuit 37 for control, and receives a control signal Sc from an external host computer via the interface circuit 39, and the control signal Sc to the read / write circuit 36 and the servo circuit. It includes a control circuit 38 to provide. Further, the control signal Sc is input to the control circuit 38, and the status signal Sc indicating the current state of the magnetic disk drive 20 is sent from the control circuit 38 to the interface circuit 39. In addition, the interface circuit 39 is coupled to the position circuit 27 for determining the position of the magnetic head 27 on the magnetic disk 24 in accordance with a command of the host computer. Here, the information of the position read by the magnetic head 24 is transmitted back to the position circuit 37 as the position signal Sp via the amplifier circuit 35 so that accurate positioning can be performed by the servo circuit. Moreover, power is supplied to all of these circuits via connector 42 along with other merged circuits.

In the following, some additional explanations are given for the various signals of the interface circuit in the present invention. As the specification of the interface used for the connector 42, specifications of a small computer system interface (SCSI), an IDE (or PC / AT), and a PCMCIA-ATA (AT Attachment) which are standardized in the near future can be used. Among these interface specifications, especially with regard to SCSI and IDE, these electrical specifications differ from the electrical specifications of IC memory cards made in accordance with PCMCIA. Therefore, it is impossible for a disk drive made in accordance with SCSI or IDE, and the IC memory card to be generally used. On the other hand, since PCMPIA-ATA provides an extended function of the PCMPIA PC Card specification, a disk drive made according to PCMCIA-ATA and a disk drive made according to PCMCIA can be inserted into the same slot of the host computer. Therefore, in the preferred embodiment, PCMCIA-ATA may be selected as the interface.

Also, a power supply voltage of 3-3.3V may be preferably used. In a typical electronic circuit, power consumption can be reduced by operating the circuit at a relatively low voltage. IC memories operating at low voltages can be obtained due to recent developments in electronic circuit design. However, a reduction in the voltage supplied to the mechanical components does not always result in a reduction in power consumption. On the contrary, in this case, the ratio of the power consumption of the electronic circuit for driving the mechanical component to the power consumption of the mechanical component itself is relatively easy to increase. Firstly, the spindle motor can be improved, so that the operation can be realized at a low voltage. Secondly, the diameter of the bearing means can be made smaller and thus the load torque can be reduced. Third, a head with a lower pressure load can be adopted, so that the load torque can be reduced during operation. Fourth, a housing made of metal including iron can be adopted, and the shield against various electrical noises can be improved.

In addition, as shown in FIG. 6, a plurality of insertion guide portions 50 are provided in predetermined portions of each side having the longer dimension of the housing 21. The insertion guide 50 is intended for inserting the housing 21 into a slot of the host computer so that the disk drive can be arranged in an operational state if each connector of the host computer and the disk drive are connected to each other. These insertion guide portions 50 are configured to have a thickness less than the overall thickness of the housing 21. As is apparent from FIG. 7, the disk 24 is disposed approximately at the center position with respect to the thickness direction of the housing 21. Thus, there is a plane space 30 between the disk 24 and the substrate 22 and another plane space 31 between the disk 24 and the lid 23.

In the vicinity of the arm 28 in the space 30, an IC 35a constituting the first stage amplifier circuit 35 for amplifying a very small read signal reproduced by the magnetic head 27 is coupled. Furthermore, in space 30, an IC for processing an analog signal, for example, IC 36a constituting part of the read / write circuit 36 and IC 37a constituting part of the position circuit 37 are also combined.

On the other hand, in space 31 located opposite the space 30 with respect to the disk 24 and separated from the space 30 by the disk 24, the IC 36b for constituting the rest of the read / write circuit 36, for example, an IC for processing a digital signal, is located. IC 36b constituting the rest of the circuit 37, IC 38a constituting the control circuit 38 and IC 38a constituting the interface circuit 38 are combined.

All electronic components 70 including the ICs 36a-39a described above are assembled on respective surfaces of the first body portion 40 and the second body portion 40b of the printed circuit board 14 disposed proximate to the inner wall surfaces of the substrate 22 and the cover 23, respectively. The electronic component 70 is included in the housing 21 together with the printed circuit board 14. Preferably, the printed circuit board (PCB) 14 is a flexible printed circuit board (FPC) 40 bent to the lower first body portion 40a and the upper second body portion 40b. In this case, the flexible printed circuit board 40 has two connecting band portions 40c and 40d to which the lower first body portion 40a and the upper second body portion 40b are coupled to each other. The following explains in more detail why the longer side of the housing 21 has been selected as the bent part (connection) of the FPC40, which joins its upper and lower parts together. As shown in Figs. 4 and 6, the FPC circuit patterns on the upper and lower sides are connected on the FPC. The signal flows from the magnetic head through the connector via the head IC, the demodulation circuit (analog) of the read / write circuit, and the digital processing circuit. As described above, the signals and the control signals output from the demodulation circuit are arranged to pass through the connecting portion in view of the analog circuit portion and the digital circuit portion separated between the lower side and the upper side of the FPC, respectively. Both the short side and the long side of the housing can be selected as the location where these connections are arranged. Further, as described above, the connector is attached to one of the short sides, while the head actuator is disposed in the vicinity of one of the short sides. Thus, if the upper and lower sides of the FPC are connected to each other with short sides, they must be connected at the side of the head actuator. This connection structure is disadvantageous in that the entire path to the signal becomes longer. On the contrary, if the upper and lower sides of the FPC are connected to each other on the long side, the above-described signal flow can be realized without difficulty in arranging the circuit pattern. However, if a disk having a diameter of 4.8 cm (1.87) is engaged in a memory card sized housing, the disk is likely to protrude out of the housing and to hit the long side of the housing. To avoid this problem, the portion of the connection where the disc protrudes out of the housing is cut off. In this structure, the connection can be reasonably arranged at the long side of the housing. In this case, it is advantageous to separate the connection into two parts as shown in FIG. 6 so that the elastic force generated at the connection can be reduced when the FPC is bent backwards.

8 and 9 are schematic diagrams showing a preferred embodiment of the magnetic head evacuation assembly in the magnetic disk drive according to the present invention. More specifically, FIG. 8 is a plan view showing a portion of the magnetic head evacuation assembly, and FIG. 9 is a side view diagrammatically showing the magnetic head evacuation assembly.

Magnetic disk drives and IC memory cards used in personal computers require a high degree of durability against external magnetic fields as well as shock. IC cards do not allow data to become abnormal even in magnetic fields as strong as 1K Gauss (100 Gauss). However, devices with aluminum sheaths / substrates are generally not capable of withstanding this strong magnetic field. In general, in a magnetic disk drive, the magnetic head and the media portion (magnetic disk) should be placed in a magnetic field weaker than 5 Gauss.

In accordance with the invention a steel substrate / cover is employed as described above to completely shield magnetization. Steel sheets having a thickness of about 0.4 mm exhibit a shielding effect to a sufficient degree to satisfy the above requirement. However, there is often a problem in that the pressed steel sheet has a residual magnetism as large as about several tens of Gauss. Therefore, in order to solve this problem, magnetic annealing is performed as necessary.

In order to minimize the effects caused by external magnetic fields, it is important that the magnetic head is retracted into the data area when the power is shorted. This is because the magnetic head has a great influence to concentrate the magnetic flux, and the data is affected by the magnetic field of about 10 Gauss and easily erased by the magnetic field of about 100 Gauss. On the other hand, in a disk medium without a magnetic head, data are not erased with each other due to strong magnetic force of about 1000 Gauss. It is inevitable to employ mechanical evacuation assemblies that do not rely on voice coil motor (VCM) drives, especially in view of the fact that portable disks are affected by magnetic field fluctuations when transported.

In particular, magnetic disk drives having floating magnetic heads allow magnetic heads to be retracted to a parking zone when the disk is stopped to avoid damage to the data area during a Contact Start Stop (CSS) operation. It is essential to provide a head evacuation assembly and an actuator locking assembly for holding the evacuated magnetic head. Even in a magnetic disk drive using a negative pressure slider (zero load slider) that does not perform the CSS operation, it is necessary to employ a retraction and locking operation from the fact that the magnetic head collides with the medium when an external shock is applied thereto. Moreover, a magnetic disk drive having an unloading mechanism needs a mechanism to move the magnetic head to the unloading position and to be supported in that position when the power is shorted.

Generally, the magnetic head evacuation assembly uses (1) a return spring, (2) the back EMF of the spindle motor to retract the actuator, or (3) the use of gravity. In addition, the actuator locking assembly uses (1) a ratchet mechanism, (2) uses frictional force, or (3) uses magnetic force.

However, as long as a linear spring is used, in the conventional magnetic head retracting assembly 1, the return spring shows a change in offset force depending on the position on the data area and greatly affects the control system. Moreover, an excessively large offset force is applied to the opposite position of the retracted area, which causes the increase in power consumption. In the case of the evacuation assembly 2, the back EMF of the spindle motor is reduced with the reduction of the magnetic disk drive size, and a sufficiently large evacuation force cannot be obtained. Also, the magnetic head evacuation assembly 3 using gravity cannot be applied to a balanced rotary actuator which is used inexpensively these days. Moreover, in the current small disk drive, it is not allowed to determine the direction of installation, and the assembly 3 is not useful.

The actuator locking assembly 1 also needs something like a solenoid to release or support the actuator. The actuator locking assembly 2 requires a delicate and cumbersome setting. Even in the case of the locking assembly 3 which performs so-called catching by using the magnetic force of the magnet, the effective range is limited to near the standby area. A retract assembly using a return spring has a locking capability, but the locking force is weaker and less practical than a retracting force unless a magnetic spring is used.

The present invention thus employs a retract assembly using a magnet as shown in FIGS. 8 and 9. Here, the head assembly has a rotatable actuator 29 and a evacuated magnet 85 at the outer edge of the flat coil 86 of the actuator 29 to hold the magnetic head 27 in the retracted state. Moreover, the evacuation yoke 87 is disposed above and below the evacuation magnet 85 to form a closed magnetic path.

Specifically, referring to the graph of FIG. 10 and the alteration structure of FIG. 11, in the magnetic circuit, the gap G is a value of the value X + X ₀ obtained by adding a predetermined integral constant X ₀ to the moving distance X of the magnetic head. It is set in the data area to change in proportion to the inverse. Further, a stepped portion 87-1 is formed in the yoke 87 so that the gap value g decreases sharply in the lock region. In this form, a constant torque is generated in the data area which is larger than the static friction force of the bearing means 46. On the other hand, the torque suddenly increases in the locking area on the outside of the magnetic disk. Thus, a large support torque is obtained and the magnetic head is reliably locked.

12 is a schematic diagram illustrating a model of a magnetic circuit for explaining the principle of the magnetic head evacuation assembly according to the present invention.

In general, there are many ways to calculate the magnetic attraction, and most of the methods using the change ratio of magnetic energy are conveniently used and will be described herein.

The magnetic energy W of the system, expressed by the magnetic force NI, the magnetic flux Φ, and the magnetoresistance R, is given by

The generated force is as follows by the differential magnetic energy in the direction of movement.

Consider a magnetic circuit model as shown in FIG. In this case, magnetic energy is stored in space, magnets and yokes. From here,

Assuming that the magnetoresistance inside the yoke can be neglected (or no magnetic energy exists), the magnetoresistance R of this magnetic circuit can be expressed as follows.

If μo = μr

On the other hand, the magnetic force NI is given by

So, assuming that the area S 'does not change,

Therefore, the generated force is given by

As is apparent from the above description, the large force generated can be obtained when the magnet is thick with respect to the gap, and the gap change ratio becomes large. In order to get a certain force regardless of position X,

Since it is practically difficult to produce a shape having this function, a substantially constant torque can be obtained by linear change if the gap interval l _g is made sufficiently larger than the thickness of the magnet, l _m .

If the device is used as a lock, steps or stages may be provided so that this gap change is large enough. 13 shows that a substantially constant evacuation force can be obtained over a sufficient stroke of the head 27, according to the actual measured results for the gap changeable head evacuation mechanism, and about 4 to 9 times the torque for the evacuation force. A graph showing the results. According to the measured results, a substantially constant evacuation force can be obtained over a sufficient stroke of the head 27, and about 4 to 9 times the torque for the evacuation force so that sufficient performance can be achieved as the lock mechanism. Occurs at the lock position on the right side of. The support torque at this lock position becomes larger as the large thickness (l _m ) of the magnet 87, as can be clearly understood from the actual measured results of FIG. 13 and the magnetic circuit model of FIG.

14 is a perspective view of an example of the area change type evacuation mechanism. In FIG. 14, the overlapping regions of the retracted magnet 85 and the retracted yoke 87 are changed inside the plane between them in the direction in which the magnetic head 27 is displaced so that the head 27 is retracted. In particular, the overlapping area between the magnets 85 and the yoke 87 gradually becomes larger in the form of a straight line function to the right, and the width of the yoke 87 increases sharply by forming another step 87-2 with respect to the face direction of the yoke 87. do. With this structure, the change in the retraction force for the travel distance X can be calculated using the magnetic circuit model shown in FIG.

Therefore, the force generated is as follows.

That is, a predetermined force can be obtained by the linear change of the area S.

In the lock area, the stepped portion is arranged in the same manner as in FIG. 10 so that the support torque is increased and the magnetic head can be reliably locked.

Fig. 15 shows another example of the evacuation mechanism for the magnetic head in the magnetic disk drive according to the present invention. In this example, the magnet 85 is not disposed in the moving part and the magnet 85 as a permanent magnet is assembled with a part of the yoke 87 in the fixed part. As a soft magnetic material, the iron plate is disposed in the moving part. This arrangement provides an effect similar to that of the other embodiments. In this example, however, magnetic circuits other than the gap are easily formed, and in this case, part of the magnetic flux generated by the permanent magnet does not contribute to the generation of the repelling force. For this reason, the design of the magnetic circuit is more difficult. In this embodiment, the yoke 87 is made of a metal plate substantially centered with the center of rotation, and the center shape and other groove shapes are finished to a predetermined shape.

In the example of the head evacuation mechanism and the lock mechanism according to the magnetic disk drive of the present invention, a substantially constant evacuation force throughout the entire area of the magnetic disk can be generated by a simple mechanism, and a sufficiently large locking force is generated at the lock position. Can be. Thus, a compact and high reliability magnetic disk drive can be achieved. In these embodiments, the direction of the magnetic flux is present in the axial direction of the actuator pivot but can be set radially.

Claims (8)

A disc drive comprising, in a rectangular housing 21, at least one disc for storing information, and a head assembly for performing a read / write operation on the disc, wherein the head assembly reads information at a predetermined position on the disc. A head 27 for performing a read / write operation corresponding to a write / write operation, a rotary actuator 29 for moving the head to a predetermined position on the disc, and a evacuated magnet provided in an external fringe portion of the actuator 29. And an evacuation yoke 87 having a first portion above the movement path of the evacuated magnet and a second portion below the path, the height of the gap between the first and second parts being defined by And the head is configured to decrease in one direction, and the head is moved by the interaction between the evacuated magnet and the evacuated yoke. And move to a parking zone of the disk at any location above the zone to be evacuated. The disk drive of claim 1, wherein the height of the gap is configured to convert the movement path to retract the head to a predetermined position. 3. The method of claim 2, wherein the height of the gap is expressed by the relation 1 / (x + xo) with respect to the displacement value x and the integral constant Xo of the head to retract the head to a predetermined position by magnetic attraction. Disk drive configured to change approximately. 3. The disk drive according to claim 2, wherein the evacuation yoke (87) has an area where the height of the gap becomes extremely small at the position where the head is finally locked. 3. A disk according to claim 2, wherein a substantially constant evacuation force is generated when the head is on the data area, the evacuation force being rapidly increased at the position where the head finally locks with the height of the gap as a very small value. drive. The overlap region between the evacuated magnet 85 and the evacuated yoke 87 corresponds to a first subregion corresponding to a head located above the data area and a head located above the standby area. And a second subregion, the overlapping region having a thickness in a radial direction with respect to a rotation axis of the actuator which is converted along a movement path of the evacuation magnet to retract the head to a predetermined position. 7. The disk drive according to claim 6, wherein the thickness of the areas between the evacuated magnets (85) and the evacuated yokes (87) is converted as a linear function in the first subregion. 7. The disk drive of claim 6, wherein the thickness is substantially constant in the first subregion by varying the thickness in the displacement direction of the head such that the thickness increases as the displacement of the head increases.