GB2245747A

GB2245747A - Flexible disk drive

Info

Publication number: GB2245747A
Application number: GB9108595A
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: DE4121558A1; JPH0467347A; KR940006884B1; JP2731452B2; GB9108595D0; KR920001475A

Abstract

A flexible disk drive for reading data from and/or writing data in a flexible disk with magnetic heads comprises a flexible disk (1) rotative driving means (2) for supporting and rotating the flexible disk, two magnetic heads (3A, 3B) for reading data from and/or writing data to the recording tracks formed in the opposite surfaces of the flexible disk, magnetic head support means (19A, 19B) for supporting the magnetic heads, capable of being attracted toward the flexible disk by the agency of gasflow generated by the rotating flexible disk over the surfaces of the flexible disk, elastic support means for elastically supporting the magnetic head support means, magnetic head position means (5) for positioning the magnetic heads at given positions on the flexible disk, and a sealed casing containing those components. <IMAGE>

Description

FLEXIBLE DISK DRIVE This invention relates to a magnetic disk drive. More

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

Hard disk drives are generally costly because hard disks are expensive, and are comparatively heavy because they use hard disks.

According to the present invention there is provide a flexible disk drive comprising: disk driving means for fixedly supporting and rotating a flexible disk; a read/write magnetic head which reads data from and writes data to the flexible disk; magnetic support means which supports the magnetic head and is pulled toward the flexible disk by gasflow generated by the rotating flexible disk over the surface of the flexible disk; elastic support means f or elastically supporting the magnetic head support means; magnetic head locating means for locating the magnetic head at a desired position on the flexible disk; and a sealed casing containing these components.

The flexible disk drive, as compared with the conventional flexible disk drive, is able to place the magnetic head closer to the flexible disk by the magnetic head support means to read data from and write data to the flexible disk drive. Therefore, the flexible disk drive has high vibration resistance, excellent impact resistance, excellent contamination resistance, and a lightweight, compact 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 X1554 flexible disk drive of Figure 1; Figure 3 is plan view of a swing arm; Figure 4 is a sectional side elevation showing the positions of magnetic head support members relative to a flexible disk; Figure 5 is a plan view of a magnetic head support member; is Figure 6 is a sectional view taken on line A-A' in Figure 5; Figure 7 is a plan view of a gimbal for supporting a magnetic head support member on a load beam; Figure SA is a side elevation of a magnetic head support member as the flexible disk is stopped; Figure 8B is a side elevation of assistance in explaining the action of the magnetic head support-while the flexible disk is rotating; Figure 9 is a plan view of a flexible disk having anisotropic extending characteristics; Figure 10 is a diagrammatic illustration of a servosector; and Figure 11 is a flow chart of a head position correcting program to be executed by a servo mechanism.

Referring to Figures 1 and 2, a flexible disk drive comprises a flexible disk 1, two read/write magnetic heads 3A and 3B for reading data from and writing data in the flexible disk 1, a swing arm 4 supporting the magnetic heads 3A and 3B, a stepping motor 5, ie, magnetic head driving means, for turning the swing arm 4 to move the magnetic heads 3A and 3B respectively in directions along the radii of the flexible disk 1, an upper printed circuit board 6 carrying a control circuit for controlling the operation of the flexible disk drive, and a base plate 7 for supporting those components.

Referring to Figures 1 and 2, the spindle motor 2 is screwed to the motor mount of the base plate 7 with K1554 its upper surface flush with the upper surface of the base plate 7. The spindle motor 2 supports the flexible disk 1 of 5.08 cm in diameter (2 inch) and rotates the same at a high rotating speed on the order of 3600 rpm.

The upper printed circuit board 6 is disposed over the flexible disk 1 so that the distance between the lower surface of the upper printed circuit board 6 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 7. Consequently, the upper and lower surfaces of the flexible disk 1 are exposed to the same action of airflow when the flexible disk 1 is rotated, so that vertical fluctuation of the flexible disk 1 is prevented.

Two pinions are mounted one over the other on the output shaft 8 of the stepping motor 5 and are pressed to each other with a spring, not shown, to eliminate plays between the pinions 9 and a rack 10 for accurate positioning of the magnetic heads 3A and 3B. The magnetic heads 3A and 3B are attached, respectively to one end of an arm 11A and one end of an arm 11B. The rack 10 is formed on the other ends of the arms 11A and 11B. The arms 11A and 11B are fixed for swing motion to a rotary shaft. As the arms 11A and 11B are turned by the rotary shaft 12, the magnetic heads 3A and 3B are moved in the radial directions of the flexible disk 1 to positions corresponding to desired tracks for read/write operation.

An upper cover 14 is fixed to the base plate 7 with four screws 13 to cover those components mounted on the base plate 7. An elastic packing 14 is inserted between the surfaces of the flange joint of the base plate 7 and the upper cover 14 to seal the flange joint. A controller printed circuit board 16 carrying a control circuit for controlling the operation of the flexible K1554 circuit for controlling the operation of the flexible disk drive is disposed under the base plate 7. A lower cover is attached to the base plate to cover the controller printed circuit board 16. An electric connector 18 is attached to one side of the controller printed circuit board 16 to connect the control circuit electrically to a computer. The electric connector 18 projects outside from the lower cover 17.

Referring the Figure 34, the upper arm 11A extending over the upper surface of the flexible disk 1 and a lower arm 11B extending under the lower surface of the flexible disk 1 are supported on the rotary shaft 12 so as to form an angle e = 54.20 therebetween.

The magnetic heads 3A and 3B are supported on magnetic support members 19A and 19B attached to the respective extremities of the upper arm 11A and the lower arm 11B, respectively. The magnetic heads 3A and 3B are connected by wires 20 to a FPCB (flexible printed circuit board) 21 electrically connected to the controller printed circuit 16 to transmit signals. The wires 20 are extended along the arms 11A and 11B for swing motion together with the arms 11A and 11B, and are held fixedly on the arms 11A and 11B by holding members 22 provided in the middle portion of the arms 11A and 11B and on load beams 23 by holding members 24, respectively.

The swing arm 4 is driven for swing motion by the stepping motor 5. The rack 10 engaging the pinions 9 mounted on the output shaft of the stepping motor 5 is formed on one end of the swing arm 4 opposite the ends supporting the magnetic heads 3A and 3B.

Referring to Figure 4, the magnetic head support members 19A and 19B are disposed on the opposite sides of the flexible disk 1 at different positions, respectively.

The magnetic head support members 19A and 19B are supported on gimbals 25 provided on the load beams 23, z K1554 respectively,-for swing motion.

The magnetic head support members 19A and 19B are substantially the same in construction and hence only magnetic head support members 19A will be described. Referring to Figures 5 and 6, the magnetic head support member 19A is formed in a substantially sectorial shape and is provided in its central portion with a hole 26 for receiving the magnetic-head 3A. An inclined surface 27 is formed in one side of the magnetic head support member 19A facing against the direction A of rotation of the flexible disk 1 to guide airflow generated by the rotating flexible disk 1 into the space between the magnetic head support member 19A and the flexible disk 1. since an air layer contiguous with the surface of the flexible disk 1 moves together with the flexible disk 1 as the flexible disk 1 rotates, the outer side surface 28 and inner side surface 29 of the magnetic head support member 19A are formed in arcs of circles having radii as large as the radius of a circle defining the circumference of the flexible disk 1 to reduce undesired force of airflow acting on the magnetic head support member 19A. Airflow is guided by the inclined surface 17 into the space between the flexible disk 1 and the magnetic head support member 19A and flow at a high velocity through the space, whereby the flexible disk 1 is attracted toward the magnetic head support member 19A. Airflow flowing outside the magnetic head support member 19A flows smoothly along the outer side surface 28 and inner side surface 29 of the magnetic head support member 19A respectively having the shapes of arcs of circles conforming to the direction of flow of the airflow. A groove 31 having a closed end 30 is formed in the central portion of the magnetic head support member 19A. The side surfaces 32 and 33 are arcs of circles concentric with those including the outer surface 28 and inner K1554 surface 29 of the magnetic head support member 19A.

The gimbals 25 are the same in construction and hence only one of-the gimbals 25 will be described. Referring to Figure 7, the gimbal 25 has a fixed portion 34 to be attached adhesively to the load beam 23, and provided with six positioning holes 35 which engage six positioning projections (not shown) provided on the load beam 23 for positionin4 the gimbal 25 on the load beam 23, respectively, and a rocking portion 36 to which the magnetic head support member 19A is attached adhesively.

The rocking portion 36 is supported by the fixed portion 34 for rocking motion about the x-axis and the y axis, and movement along the z-axis (Figure 8B).

Referring to Figures 8A and 8B, the magnetic head support member 19A(19b) is disposed close to the flexible disk 1. A negative pressure is produced in the groove 31 of the magnetic head support member 19A (19B) as the flexible disk 1 is rotated at a high rotating speed, so that magnetic head support member 19A (19B) is attracted toward the flexible disk 1 as indicated by an arrow.

Since conventional flexible disk drives use a thin flexible disk having a thickness as small as 30 gm, the thin flexible disk is attracted toward the magnetic head support member. Since the flexible disk 1 used by the flexible disk drive of the present invention is a thick flexible disk having a thickness not smaller than 72 gm, the magnetic support member 19A (19B) is attracted toward the flexible disk 1, forming a dimple of a depth of the order of several tens of micrometers in the 30- flexible disk 1. At the same time, portions of the flexible disk I is attracted slightly into the groove 31 of the magnetic head support member 19A (19B) as shown in Figure 8B.

The circular base of the flexible disk 1, may be punched out from a film of an organic high polymer, such K1554 as polyethelene terephthalate, unwound from a roll of the film while a 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 heat and humidity within the casing.

Referring to Figure 9, a flexible disk which is anisotropic in extension, has an elliptic shape having a major axis X and a minbr 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. Sectorial 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 10, 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 3A and 3B are identical, the respective track widths of the servo signals F and the tracks T coincide with the gap length of the magnetic heads 3A and 3B. Off-track occurs when the gaps of the magnetic heads 3A and 3B deviate from the desired track T.

A magnetic head position correction operation to be carried out by servomechanism according to the present invention will be described hereinafter with reference to Figure 11.

The magnetic heads 3A and 3B 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 1 K1554 - a - dislocation. A 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 3A and 3B are correctly located at fine track position by foregoing correcting procedure, tracking is continued. If the magnetic heads 3A and 3B are not located at thefine track position, the correcting procedure is repeated again.

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 flexible disk drive has excellent vibration resistance.

is z K1554

Claims

1. A flexible disk drive comprising: disk driving means for rotatably supporting and rotating a flexible disk; a first magnetic head for reading data from and/or writing data to the flexible disk, disposed opposite one of the surfaces of the flexible disk; first magnetic head support means for supporting the first magnetic head, capable of being attrabted toward the flexible disk by means of gasflow generated by the rotating flexible disk over the surface of the flexible disk; elastic support means for elastically supporting the first magnetic head support means; and a sealed casing containing the flexible disk; the rotative driving means, the first magnetic head, the first magnetic head support means, and the elastic support means.

2. A flexible disk drive according to Claim 1, further comprising magnetic head positioning means for positioning the first magnetic head at a given position on the flexible disk.

3. A flexible disk drive according to Claim 1 or Claim 2, further comprising a second magnetic head disposed opposite to the other surface of the flexible disk.

4. A flexible disk drive according to Claim 3, further comprising second magnetic'head support means for supporting the second magnetic head, capable of being attracted toward the flexible disk by means of gasflow' generated by the rotating flexible disk over the surface of the flexible disk.

5. A flexible disk drive according to Claim 4, further comprising elastic support means for elastically supporting the second magnetic head support means.

6. A flexible disk drive according to any one of Claims 3 to 5, wherein the second magnetic head is positioned by the magnetic head positioning means.

- 10 K1554

7. A flexible disk drive comprising: a flexible disk; driving means for supporting and rotating the flexible disk; two magnetic heads for reading data from and/or writing data to the recording tracks of the flexible disk; magnetic head support means for supporting the magnetic heads, capable of being attracted toward the flexible disk by means of gasflow generated by the rotating flexible disk'over the surfaces of the flexible disk; elastic support means for elastically supporting the magnetic head support means; magnetic head positioning means for positioning the magnetic heads at given positions on the flexible disk; and a sealed casing containing the flexible disk, the rotative driving means, the two magnetic heads, the magnetic head support means, the elastic support means, and the magnetic head positioning means.

8. A flexible disk drive according to Claim 7, wherein the elastic support means are gimbals.

9. A flexible disk drive comprising: a flexible disk; driving means for supporting and rotating the flexible disk; two magnetic heads for reading data from and/or writing data to the recording tracks formed in the opposite surfaces of the flexible disk; magnetic head support means for supporting the magnetic heads, capable of being attracted toward the flexible disk by means of gasflow generated by the rotating flexible disk over the surfaces of the flexible disk, wherein each of two magnetic head support members included in the magnetic means has an outer side having the shape of a circular arc conforming to the shape of the signal recordingregion of the flexible disk; elastic support means for elastically supporting the magnetic head support means; magnetic head positioning means for positioning the magnetic heads at given positions on the flexible disk; and a sealed casing containing the flexible disk, the K1554 rotative driving means, the two magnetic heads, the magnetic head support means, the elastic support means, and the magnetic head positioning means.

10. A flexible disk drive substantially as hereinbefore described with reference to, and as illustrated by. the accompanying drawings.

Published 1991 atThe Patent Office, Concept House. Cardiff Road, Newport. Gwent NP9 1 RH. 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.