GB2245748A

GB2245748A - Flexible disk drive

Info

Publication number: GB2245748A
Application number: GB9108598A
Authority: GB
Inventors: Shoichiro Saito; Masao Ohkita; Shinkichi Sasaki
Original assignee: Alps Electric Co Ltd
Current assignee: Alps Alpine Co Ltd
Priority date: 1990-06-29
Filing date: 1991-04-22
Publication date: 1992-01-08
Also published as: GB9108598D0; JPH0467374A; DE4121467A1

Abstract

A flexible disk drive having magnetic heads which write data to and/or read data from a flexible disk comprises a flexible disk (1), rotative magnetic disk driving means (2) for supporting and rotating the flexible disk, two magnetic heads (3) for reading data from and/or writing data to recording tracks formed in the opposite surfaces of the flexible disk, magnetic head support means (21) which supports the magnetic heads so that the magnetic heads float over the corresponding surfaces of the flexible disk, magnetic head positioning means (6) for positioning the magnetic heads respectively at desired positions on the flexible disk and a sealed casing accommodating those components. <IMAGE>

Description

2:: 2 -1, - --1 ' 7:-j. n 1 - FLEXIBLE DISK DRIVE This invention relates

to a magnetic disk drive and, more particularly, it relates to a flexible disk drive of a fixed disk drive system.

Hard disk drives are costly because hard disks are expensive, are comparatively heavy because they use hard disks, and have the possibility of crushing the magnetic disk and the.magnetic head.

According to the present invention there is provided a flexible disk drive comprising a flexible disk, flexible disk drive means for fixedly supporting and rotating the flexible disk, a magnetic head for reading data from and writing data to the flexible disk, magnetic head support means for supporting the magnetic is heads in a floating state, magnetic head positioning means for positioning the magnetic head at a desired position on the flexible disk, and a sealed casing containing those components.

The flexible disk drive, as compared with a conventional flexible disk drive, positions the magnetic head closer to the flexible disk by means of the magnetic head support means (typically a slider) for read/write operation. Thus, the present invention provides a flexible disk drive having a high vibration resistance, shock resistance, excellent contamination resistance, a high density, a large capacity, and compact and lightweight construction.

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 is a plan view of a flexible disk drive in a preferred embodiment according to the present invention, in which an upper cover is removed; Figure 2 is a sectional side elevation of the flexible disk drive of Figure 1; K1555 Figure 3 is a plan view of a swing arm; Figure 4 is a perspective view of a head slider; Figure 5 is a side elevation showing the positional relation between the head slider and a flexible disk; Figure 6 is a plan view of a stepping motor; Figure 7 is a sectional side elevation of the stepping motor of Figure 6; Figure 8 is a plan view of a flexible disk having anisotropic extension characteristics; Figure 9 is an illustration of servo sectors; Figure 10 is a flow chart of a head position correcting program to be executed by a servomechanism; and Figure 11 is a perspective view of assistance in explaining the manner of practical application of the flexible disk drive of Figure 1.

Referring to Figures 1 and 2, a flexible disk drive in a preferred embodiment according to the present invention comprises a flexible disk 1, a spindle motor (magnetic disk driving means) 2 for rotatably supporting and rotating the flexible disk 1, two magnetic heads 3 for reading data from and writing data in the flexible disk 1, head sliders 4 respectively supporting the magnetic heads 3, a swing arm 5 supporting the head sliders 4 on its extremities, a stepping motor (magnetic head positioning means) 6 for turning the swing arm 5, an upper printed circuit board 7 mounted with a control circuit for controlling the flexible disk drive, and a base plate 8 supporting those components.

An upper cover 10 is fixed to the base plate 8 with four screws 9 to cover those components mounted on the base plate 8. An elastic packing 11 is inserted between the surfaces of the flange joint of the base plate 8 and the upper cover 10 to seal the flange joint.

is K1555 A conductive packing may be used to suppress the adverse influences of internal and external noises. A controller printed circuit board 12 carrying a control circuit for controlling the operation of the flexible disk drive is disposed under the base plate 8. A lower cover 14 is attached to the base plate 8 to cover the controller printed circuit board 12. An electric connector 13 is attached to one side of the controller printed circuit board 12 to connect the control circuit electrically to a computer. The electric connector 13 projects outside from the lower cover 14.

Referring to Figure 2, the upper printed circuit board 7 is disposed over the flexible disk 1 so that the distance between the lower surface of the upper printed circuit board 7 and the upper surface of the flexible disk 1 is equal to the distance between the lower surface of the flexible disk 1 and the upper surface of the base plate 8. Nonwoven sheets 15 are applied respectively to the upper surface of the base plate 8 facing the flexible disk 1 and to the lower surface of the upper printed circuit board 7 facing the flexible disk 1.

The spaces of the same width formed on the opposite sides of the flexible disk 1 stabilize airflows generated by the rotating flexible disk 1 over the opposite surfaces of the same.. The nonwoven sheets 15 arrest dust within the sealed casing and mitigate rectifying action on the flexible disk 1 to apply a satisfactory rectifying action on the flexible disk 1.

Since the rectifying action is liable to be disturbed by the swing arm 5, the swing arm 5 is disposed so that its upper arm 16A and lower arm 16B are flush respectively with the upper printed circuit board 7 and the base plate 8.

Referring to Figure 3, the upper arm 16A and the lower arm 16B are supported on a rotary shaft 17 so that is K1555 the upper arm 16A extends along the upper surface of the flexible disk I and the lower arm 16B extends along the lower surface of the flexible disk 1.

The magnetic heads 3 are supported on the head sliders 4 attached to the respective extremities of the upper arm 16A and the lower arm 16B, respectively. The magnetic heads 3 are electrically connected to an FPCB (flexible printed circuit board) 19 electrically connected to the upper printed circuit board 7 by wires 18 extended along the side surface of the upper arm 16A and the lower arm 16B for swing motion together with the upper arm 16A and the lower arm 16B, respectively. The wires 18 are fixedly held on the arms 16A and 16B by holding members 20 provided in the middle portions of the arms 16A and 16B and on load beams 21 by holding members 22. The load beams 21 are formed of an elastic stainless steel.

The swing arm 5 is turned by the stepping motor 6. Two pinions 23 are mounted on the output shaft of the stepping motor 6 and engage a rack 24 formed on one end of the swing arm 5 opposite the extremities on which the magnetic heads 3 are supported.

Referring to Figure 4, the head slider 4 has two flying surfaces 4A and 4B, and a tracking surface 4C provided with a gap G for the magnetic head 3. First slopes 4F and 4G are formed in the front ends 4D and 4E of the flying surfaces 4A and 4B, respectively. Second slopes 4H and 41 of an inclination smaller than that of the first slopes 4F and 4G are formed behind the first slopes 4F and 4G, respectively.

The head slider 4 receives airflow generated by the rotating flexible disk 1 rotating at a high rotating speed from the front ends 4D and 4E along the first slopes 4F and 4G. A positive pressure produced between the flying surfaces 4A and 4B and the surface of the 4 K1555 flexible disk 1 by the airflow causes the head slider 4 to float by a distance in the'range of approximately 0.15 Am to 0.3 Am from the surface of the flexible disk 1.

Referring to Figure 5 showing the action of the head sliders 4 while the flexible disk 1 is rotating, the head sliders 4 are separated from the corresponding surfaces of the flexible disk 1 by a distance in the range of approximately 0.15 Am to 0.3 Am. Being flexible, the flexible disk 1 flexes unavoidably when the same is rotated at a high rotating speed of the order of 3600 rpm. However, since stable positive pressures are produced in the spaces between the head sliders 4 and the corresponding surfaces of the flexible disk 1, the positive pressure checks the movement of the flexible disk 1 toward either one of the head sliders 4 and urges the flexible disk I to its neutral position, so that the flexible disk 1 is stabilized at its neutral position to enable the magnetic heads 3 to perform satisfactory read/write operations.

Referring to Figures 6 and 7, the stepping motor 6 has an output shaft 25, two pinions 26 and 27 mounted on the output shaft 25 and engaging the rack 24 of the swing arm 5, and an FPCB 19 connected to the controller printed circuit board 12.

To eliminate play between the pinions 26 and 27 and the rack 24 for the accurate positioning of the magnetic heads 3, the upper pinion 26 is mounted an the output shaft 25 for turning relative to the output shaft 25, the lower pinion 27 is fixed to the output shaft 25, and the pinions 26 and 271 are interlocked with each other by a spring 30. The pinions 26 and 27 are held in place on the output shaft 25 of the stepping motor 6 with a stop ring 28 fitted in an annular recess 29 formed in the output shaft 25. A VCM (voice coil motor) may be used instead of the stepping motor 6 as magnetic head K1555 positioning means.

The circular base of the flexible disk 1, in general, is punched out from a film of an organic high polymer, such as polyethylene terephthalate, unwound from a roll of film while tension is applied in one direction to the film. Therefore, the circular base is anisotropic in extension and is liable to be deformed in an elliptic shape by the heat andhumidity within the casing.

Referring to Figure 8, a flexible disk which is anisotropic in extension, has an elliptic shape having a major axis X and a minor axis Y. At least two sectorial servosectors S1 and S2 are formed along one direction of the major axis X and one direction of the minor axis Y, respectively. Data zones D are formed between the servosectors S1 and S2. A circular zone P, in which no data is written, is formed around the inner circumference of the flexible disk. The servosectors S1 and S2 extend radially respectively along the major axis X and the minor axis Y, which are perpendicular to each other.

As shown in Figure 9, servo signals F are recorded at regular intervals in a zigzag arrangement on the opposite sides of the centre lines C of the recording tracks T of the flexible disk. Since the magnetic heads 3 are identical, the respective track widths of the servo signals F and the tracks T coincide with the gap length of the magnetic heads 3. Off-track occurs when the gaps of the magnetic heads 3 deviate from the desired track T.

A magnetic head position correcting operation to be carried out by a servomechanism according to the present invention will be descr--bed hereinafter.

The magnetic heads 3 compare servo corrections of the servosectors S1 and S2 to see if there is any track T. If there is no dislocation, the next servo data signals are read. If there is some dislocation, the dislocation is calculated to correct the dislocation. A K1555 correction corresponding to the dislocation from a desired track T is found in a correction calculating table. A correction signal corresponding to the correction is provided. When the magnetic heads 3 are correctly located with their gaps G at a fine track position by the foregoing correcting procedure, tracking is continued. If the magnetic heads 3 are not located with their gaps G at the fine track position, the correcting procedure is repeated again.

Referring to Figure 11, the flexible disk drive is included in a computer or is removably mounted on an external disk drive mounting unit 31.

Guide grooves 33 confirming to the side shape of the casing of the flexible disk drive are formed in a front bezel 32 of the disk drive mounting unit 31 to guide the flexible disk drive for insertion and ejection. The flexible disk drive can be ejected from the disk drive -mounting unit 31 by pressing an eject button 34.

The flexible disk drive need not necessarily include the spindle motor; the flexible disk drive may be provided with a rotary flexible disk support member which can be driven by an external motor.

A vertical magnetic recording system may be employed to the further enhance recording density. The stepping motor may be substituted by a VCM for highly accurate magnetic head positioning.

As is apparent from the foregoing description, according to the present invention, a flexible disk can be used like a hard disk on a flexible disk drive of a fixed disk drive system and a large-capacity, compact, lightweight magnetic disk drive can be manufactured at comparatively low cost. Since the flexible disk is flexible, the magnetic heads and the flexible disk are not damaged even if the magnetic heads are caused to strike accidentally on the flexible disk, and the

K1555 flexible disk drive has excellent vibration resistance.

K1555

Claims

A flexible disk drive comprising: a flexible disk; disk driving means for rotatably supporting and rotating the flexible disk; a first magnetic head disposed opposite one of the opposite surfaces of the flexible disk to read data from and/or to write data to the flexible disk; a first head slider which supports the first magnetic head so that the first magnetic head floats over the surface of the flexible disk; and a sealed casing accommodating the flexible disk, the rotative disk driving means, the first magnetic head, and the first head slider.
2. A flexible disk drive according to Claim 1 further comprising magnetic head positioning means accommodated in the sealed casing to position the first magnetic head at a desired position on the flexible disk.
3. A flexible disk drive according to Claim 2 further comprising a second magnetic head disposed opposite the other surface of the flexible disk.
4. A flexible disk drive according to Claim 3 further comprising a second head slider which supports the second magnetic head so that the second magnetic head floats over the surface of the flexible disk.
5. A flexible disk drive according to Claim 4, wherein the magnetic head positioning means positions the second magnetic head at a desired position on the flexible disk.
6. A flexible disk drive according to any preceding claim, wherein a flat board is extended along the data recording surface of the flexible disk to rectify airflow generated by the rotation of the flexible disk so that the rotation of the flexible disk is stabilized.
7. A flexible disk drive according to Claim 6, wherein the flat board is a printed circuit board.
8. A flexible disk drive comprising: a flexible 1 K1555 disk; magnetic disk driving means for rotatably supporting and rotating the flexible disk; two magnetic heads disposed respectively on the opposite sides of the flexible disk to read data from and/or to write data to the flexible disk; two head sliders which support to two respective magnetic heads so that the magnetic heads float over the corresponding surfaces of the flexible disk, respectively; magnetic head positioning means for positioning the two magnetic heads respectively at desired positions on the flexible disk; a flat board for rectifying airflow generated by the rotation of the flexible disk; and a sealed casing accommodating the flexible disk, the rotative magnetic disk driving means, the two magnetic heads, the two head sliders, the magnetic head positioning means, and the flat board.
9. A flexible disk drive substantially as hereinbefore described with reference to, and as illustrated by, the accompanying drawings.

Published 1991 at The Patent Office. Concept House. Cardiff Road. Newport. Gwent NP9 IRH. Further copies may be obtained from Sales Branch, Unit 6, Nine Mile Point. Cwmfelinfach. Cross Keys. Newport. NP I 7HZ. Printed by Multiplex techniques ltd. St Mary Cray. Kent.

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