JPS5998349A - Disc drive actuator construction - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention generally relates to a storage device of a type having a rotating disk of more than IS. More particularly, the present invention provides an actuator set supporting a transducer configured to move radially with respect to one or more rotating disks for reading and writing magnetic information on the disks. The present invention relates to a rotating disk storage device having a three-dimensional structure. Such actuators are referred to as linear actuators because the transducer moves along a straight line extending generally in the radial direction of the storage disk.

The present invention provides a linear actuator that is particularly useful in magnetic storage devices of the type known in the art as Winchester-type magnetic disk storage devices. Linear actuators are juxtaposed adjacent to the periphery of one or more longitudinally spaced disks to rapidly position one or more transducers to record on the disks. The device is configured to access magnetic information. Such transducers typically have a floating read/write head. Although the present invention is described with respect to a Winchester-type disk drive, the actuator may also be used with other electromagnetic storage devices such as optical storage devices in which one or more optical transducers are incorporated within the actuator. This actuator is also useful in storage devices.

Recent developments in disks have increased track density, resulting in an attempt to make the device as compact as possible while providing actuators that can access the information stored on the disk very quickly. ing. Therefore, it has a magnetic force constant high enough to rapidly decelerate and accelerate the transducer carriage, hold the carriage rigidly against vibrations, and minimize magnetic leakage in front of the actuator adjacent to the disk. It would be desirable to provide an actuator that maintains the magnetic information recorded on the disk without adversely affecting it. Additionally, it is desired that the carriage support and drive structure minimize induced resonances when rapid acceleration and deceleration of the carriage is required.

It is also desired to reduce manufacturing costs.

U.S. Pat. No. 4,280,155 discloses a fixed disk drive having a flat rectangular base plate and a ball-shaped cover. A magnetic transducer rad carriage and positioning assembly (hereinafter also referred to as the transducer actuator assembly) is attached to the base plate adjacent the periphery of the disk, and the transducer projects outwardly from the actuator assembly. It is attached in the form of a flexible arm. The motor that rotates the disc is mounted within the housing and below the base plate. The actuator is moved inwardly and outwardly with respect to the disk by a stepper motor that drives the rack binion. Improvements in the transducer actuator assembly described above are disclosed in U.S. patent application Ser.
No. 391,782, which applications are assigned to the present applicant.

These patent applications disclose electromagnetic means for driving an actuator having two pairs of rectangular magnets (four in total), a rectangular coil attached to the carriage of the actuator and a rectangular air gap. Driven within. Linear positioning devices are also available in U.S. Pat. No. 3,619,
No. 673 and No. 3,666°971. In U.S. Pat. No. 3,619,673, a rectangular permanent magnet is used, and a rectangular coil connected to a carriage member is disposed within the air gap between the magnet and a central core pole member. There is. Current driven through the coil creates a propulsion force in the coil arrangement sufficient to move the coil arrangement along the central core. On the other hand, U.S. Pat. No. 3,666.977 discloses a similar arrangement having a central core member and a series of separate magnetic blocks around the periphery of the core, which are movable. A multi-turn drive coil is disposed within the air gap. The coil is fixedly mounted to the carriage assembly and the two move together when current is passed through the coil.

The present invention has been made in view of the above points, and it solves the drawbacks of the prior art as described above, and particularly provides an extremely effective 8.
It is an object of the present invention to provide a rotating disk storage device having an improved magnetic transducer actuator assembly capable of providing a dogleg-shaped magnetic return path.

According to one aspect of the present invention, a pair of cylindrical and radially attached magnets are provided in a floating manner and spaced apart in a pole structure with a C cross section approximately between them, Two circular coils are movably disposed within the gap between the magnet and the pole structure, and are fixed to the actuator body or mounting wings on the carriage.

By activating the coil, the actuator moves very quickly and the transducer accesses the disk at high speed. The actuator assembly generally includes a carriage and a pair of laterally spaced electromagnetic motors that provide symmetrical driving forces on the carriage. The carriage is supported for reciprocating movement between a pair of upper and lower cylindrical guide rods. The carriage of the actuator assembly has a central body portion and coil support wings extending symmetrically at sides of the central body portion. A pair of rollers is attached to the top of the carriage body, and a double pair of rollers (front and rear sets)
is attached to the lower end of the carriage body and rides on each of the upper and lower guide ronds. The actuator carriage is in juxtaposed relationship with a pair of cylindrical magnets that are secured to the support structure. An annular air gap is formed between the cylindrical magnet and the pole structure surrounding the magnet. A coil is attached to the wings of the carriage, the coil being positioned within the air gap and driven linearly with respect to the air gap and the cylindrical magnet.

When energized, the electromagnetic actuator generates a large force to rapidly position the transducer extending from the carriage body relative to the disk within the drive.

A transducer is mounted on a plurality of cantilevered flexible arms extending forwardly from the carriage body. In the preferred embodiment, a pair of laterally and symmetrically arranged linear motors are provided which together provide a strong actuating force to provide rapid access times and to dampen the carriage from vibration. It has been stabilized. Due to the unique configuration of the pole arrangement, the motor occupies a small radial space and magnetic leakage near the periphery of the rotating disk is negligible.

Hereinafter, specific embodiments of the present invention will be described in detail with reference to the accompanying drawings. Referring to FIG. 1, a magnetic disk storage device has a base 10 through which a spindle (not shown) is mounted for rotating one or more magnetic recording disks 11 and 12. supported as possible. A linear actuator 14 is provided to move one or more access transducers along a linear path extending generally radially of the rotating disk. The storage device has fixed 5.25-inch or 8-inch diameter disks with an intended track density of about 600 to 1,200 on each disk.
It is of the type known as a Winchester type drive, which has a track per inch. Winchester type storage devices are known to those skilled in the art. That is, it has a motor (not shown) for rotating the disk at high speed and a DC drive circuit (not shown) operatively connected to the actuator 14. The base 10G is mounted in a sealed housing with a ventilation system configured to prevent dust from adhering to the disk surface.

Next, the linear actuator 14 will be explained in detail. Actuator 14 is extremely small, occupying only about 2 to 3.5 inches of space extending outward from the periphery of the disks and about 1/8 inch to 1 inch from the ends of disks 11 and 12. is positioned at a distance of This actuator is capable of reciprocating the transducer over a stroke of approximately 1 to 1.5 inches, with virtually no magnetic leakage in front of the actuator near the periphery of the rotating disk. . Even if the disk is located in close proximity to the permanent magnet of the actuator assembly, the information magnetically recorded on the disk will not be adversely affected by the magnetic field of this magnet.

Actuator 14 has a fixed magnet assembly 15 and a movable transducer/coil assembly 16. In the assembled state, the transducer/coil assembly 1
6 is located within the fixed magnet assembly 15, and the rear part of the linear actuator 14 is closed by a rear pole plate 17.

A carriage 18 is centrally mounted to the assembly 16 and the front mounting has a bracket 19. Secured to bracket 19 is a series of cantilevered extensions or arms 21 that hold transducers 22-24. When accessing a disk, transducers 22-24 are juxtaposed with specific tracks on disks 11 and 12, and the transducers read magnetic information or record desired information at that specific location. Write magnetic information. Illustratively, transducers 22 and 23 access the top and bottom surfaces of disk 11 , and transducer 24 accesses the top surface of disk 12 . It should be understood that additional transducer assemblies typically access the underside of disk 12 and other disks rotating under disks 11 and 12. A transducer assembly can be provided on the underside of the illustrated assembly.

Fixed magnet assembly 15 includes a pair of cylindrical magnets 30 and 31 held within magnet housing 27. Magnet housing 27 has a front pole plate 28 and a peripheral pole arrangement 29 surrounding the cylindrical magnet and rear pole plate 17 .

The assembly 16 has a generally symmetrical construction and includes a left side projection 32 and a right side projection 33, each of which houses the previously described cylindrical magnets 30 and 31. magnet 30
and 31 are annular in cross section and are slidably fitted onto the central pole member 34. The clearance of this slip fit is indicated by reference numeral 35. A peripheral pole arrangement 29 is provided spaced from the outer periphery of the cylindrical magnet and has a thickness 36 sufficient to transmit the magnetic flux generated by the electromagnetic motor. . Peripheral pole arrangement 29 is spaced from the outer periphery of magnets 30 and 31, forming an air gap 37 therebetween.

The air gap 37 extends linearly along the length of the cylindrical magnet and peripheral ball arrangement. Air gap 37 extending along the linear direction of the magnet (typically 0.150 to 0.18
0 inches) is the air gap 37a (typically 0.200 to 0
．． 250 inches) to ensure maximum efficiency and prevent magnets from shorting to the end plates.

Magnets 30 and 31 are formed of a ceramic material such as that manufactured by the "Crucible" division of Colt Industries. Magnet assembly 15 is secured to base 10 by fixture 38.

The carriage 18 has both carriages 42 and wings 4.
On top of 2 are a left drive coil 40 and a right drive coil 41.
is installed. Retaining rings 43 and 44 are screwed to the inner end portion of the wing and serve to hold the coil in place on the wing. Mechanical retention force from the retaining ring.

In addition, adhesive 45 can be used to attach the coil to 1142. Drive coils 40 and 41 are right cylinders having an inner diameter larger than the diameter of magnets 30 and 31 and an outer diameter larger than the inner diameter of peripheral ball structure 29. The coil and magnet are provided separately. The coil is thus able to move freely within the air gap 37 formed between the outer periphery of the magnet and the peripheral pole structure. The drive coils have the same configuration,
Therefore, equal forces are applied to both sides of the carriage parallel to the carriage's linear movement path. This path of movement is determined by guide rails 25 and 26 that are fixed with respect to base plate 10 and fixed magnet assembly 15. The length of the cylindrical magnet in the direction of carriage movement is substantially greater than the length of the coil in the transducer/coil assembly, thus providing a long gap short coil linear actuator. The drive coil and its associated pair of cylindrical magnets are arranged symmetrically to form two electromagnetic motors of identical configuration, which act symmetrically on opposite sides of the carriage to maintain balance. generates a driving force.

The base 10 and peripheral pole structure 29 of the storage device;
The front pole plate 28 and the rear pole plate 17 are cast from a high permeability metal such as iron. Carriage assembly 18, including carriage arm support 20 and cantilever arm 21, is typically formed from cast or machined aluminum.

As understood from FIG. 3, the right cylindrical copper tube 46 is connected to the magnet 31.
on the outer periphery of each, forming a so-called shorted turn. This shorted turn acts as a bucking coil, quickly saturating the coil and preventing contamination of the disk. That is, the shorted turns seal or surround the periphery of the magnet to prevent particles from being dispersed into the air stream. The rear pole plate 17 and the front pole plate 28 are of integral construction or are fixedly connected to the peripheral pole arrangement. The Gaussian field remains uniform and unless the casing, i.e. the peripheral pole arrangement and the end pole members, are saturated, the strength of the Gaussian field outside the gap between the disk and the actuator is very low, approximately 3 to 4 It is Gauss. Since there is a space between the periphery of the magnet and the drive coil, the drive coil and magnet are effectively in a 70-ting relationship within the pole structure.

As shown in FIGS. 2 and 3, the carriage 18 has a double pair (front and rear) of an upper roller 47 and a lower roller 48 that are in rolling contact with the upper rail 25 and the lower rail 26, respectively. have.

Roller shafts 50 for each of the upper and lower rollers
and 51 extend perpendicularly from the surface of the carriage 18. A carriage 842 supports drive coils 40 and 41. A rail tension spring mechanism 39 orients the rail arrangement and provides tension to cause the carriage to move linearly with respect to the upper and lower rails without vibration. FIG. 3 more clearly shows the air gap 37 between the peripheral surfaces of magnets 30 and 31 and peripheral pole structure 29. FIG. Drive coils 40 and 41
It is within this gap 37 that the particles move linearly.

In its cross-sectional shape, the peripheral pole structure 29 has a pair of C-section members 62 and 63 provided oppositely. The upper and lower surfaces of the carriage wings or extensions 42, which are typically aluminum or magnesium members, extend within and spaced apart from a gap 64 formed by opposing w of members 62 and 63 and 65 and 66.

The space between the ends 64 and 65 is the extension 4 of the carriage.
2 and sufficient space to allow magnetic flux to cross the gap between the ends of C-sections 64 and 65 to form a figure-eight magnetic path. Being in close proximity. The magnetic path extends from the magnet 30 through the gap 37 to the pole structure 29 and then back through the end pole member 17 to the magnet 30 through the air gap 37a.

Such magnetic paths exist in all four quadrants.

As can be seen in FIG. 3, the shorted turns 46 are cylindrical tubes that can be press-fit onto the outside diameter of the magnet.

FIG. 4 is a side view of the stationary magnet assembly showing the end configuration incorporating front and rear annular shock absorbers 55 and 56. These shock absorbers function as fracture arresters and function to absorb kinetic energy imparted to the pole structure from the moving elements. This causes the base 10 to collide with the front and rear pole members.
This minimizes the added resonance. The magnet 30 is a slip fit on the central pole member 34 with or without a gap. The rear pole member plate 17 is removably attached to the fixed magnet assembly so that the transducer coil assembly 16 is connected to the linear actuator 14.
It can be easily taken out by pulling it out backwards. It is possible to place opposite charges on each of magnets 30 and 31 to minimize magnetic leakage. The dimensions of the air gap 37 and the slip fit of the magnets on the central pole member 34 prevent mechanical vibrations from being transmitted to the base structure 10. Shock absorbers 55 and 5
6 also attenuates magnetic forces.

Approximately 80% of the coil lies within the effective magnetic gap. Dual cylindrical coils allow for compact configurations,
The linear actuator of the present invention requires only two magnets overall, compared to four or more magnets in many prior art devices.

FIG. 5 shows a magnet of the type used in the present invention. It is a so-called circular cylindrical magnet, i.e. the poles are aligned radially within the cylinder, so that the north pole 66
is formed on the outer wall, while the south pole 67 is formed on the inner wall. Typical magnet configurations of this type are designed to create a magnetic field of up to 1,400 to 1,800 Gauss within the air gap. For a typical 8 inch Winchester type disk drive, magnets 30 and 3
1 has a length of 2.5 inches and an outer diameter of 1-1/8
The inner diameter is 1/2 inch.

In disk drives, it is important that the magnetic field in the area of the rotating disk be less than the maximum value to prevent erasure or loss of information stored on the disk. Typically, such maximum value is 10 Gauss. According to the invention, a C having a shape surrounding a cylindrical magnet and made of an appropriately selected material
It has been found that leakage flux from the rotating disk and carriage bearings can be effectively shielded by using a cross-sectional peripheral pole arrangement.

mounting the transducer on the cantilevered flexible arm; and mounting the flexible arm on the carriage;
Further details of the carriage 18 and the tension spring mechanism 39 are disclosed in the aforementioned U.S. Patent Application No. 06/352,94.
It is disclosed in No. 3. Coil lead wires 57 and 58 are provided for coils 40 and 41, and these wires are connected to a conventionally known DC drive circuit (not shown).

Although the specific configuration of the present invention has been described in detail above, the present invention should not be limited to only these specific examples, and may go beyond the technical scope of the present invention. Of course, various modifications can be made without any modification.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view showing a preferred embodiment of the linear actuator assembly of the present invention, FIG. 2 is a plan view showing the linear actuator assembly of the present invention and a portion of a disk of a storage device, and FIG. 4 is a rear view of the linear actuator of the present invention with the rear pole plate removed, FIG. 4 is a sectional view taken along line 4-4 in FIG. 3, and FIG.
Figure (This is a perspective view showing a cylindrical magnet used in the present invention. (Explanation of symbols) 14: Linear actuator 15: Fixed magnet assembly 16: Flexible transteuser/Coy JL/lli solid 18: Carriage 21: Arms 22-24: l-landucer 30.31:
Cylindrical magnet 37: Air gap 40.41: Drive coil 42: Carriage blade 462 Cylindrical copper tube

Claims (1)

[Claims] 1. A housing, an actuator base plate assembly disposed within the housing, comprising a carriage, at least one transducer attached to the carriage, and electromagnetic means for reciprocating the carriage. an actuator assembly comprising: a spindle motor mounted to the base plate; and at least one rotatable disc operatively connected to the motor within the housing; is attached to the carriage and is moved to a desired track position on the surface of the disk by reciprocation of the carriage, the electromagnetic means comprising: a) a longitudinally extending member made of a high magnetic permeability material; a longitudinally extending circular cylindrical magnet with an annular cross section surrounding the central pole; and an internal circular surface surrounding the magnet and similar to and spaced from an external surface of the magnet. an outer pole structure having a substantially annular air gap therebetween and formed of a high magnetic permeability material; b) extending longitudinally within said air gap and forming a substantially annular air gap therebetween; C) a circularly wound coil spaced from an internal circular surface of the body and an external surface of the magnet; and C) connection means for attaching the coil to the carriage and for passing an electric current through the coil. An apparatus characterized in that the coil and the carriage are integrally moved in a linear reciprocating motion. 2. In the above item 1, the electromagnetic means has a pair of electromagnetic means extending in the longitudinal direction and spaced apart from each other, and the carriage extends between the pair of electromagnetic means. A device featuring: 3. In paragraph 2 above, the connecting means has a horizontal extension extending from the carriage on which the coil is mounted, and the external pole structures of each of the pair of electromagnetic means are opposite to each other. It has a C cross-sectional shape,
The apparatus wherein the carriage extension extends between and spaced apart from the gap formed by the opposing ends of the C-section. 4. The apparatus of claim 3, wherein the carriage extension is formed of a high magnetic permeability material, and a magnetic path substantially surrounds the magnet to shield leakage magnetic flux from the disk. 5. In the above item 2, shock absorbing buffer means is provided juxtaposed to the end of the magnet and in contact with the inner surface of the end portion of the external pole structure, and the buffer means A device extending into the annular gap at a longitudinally moving end to damp magnetic forces and cushion excessive movement of the coil. 6. The device of item 2 above, wherein the magnet is a sliding fit on the central pole. 1. The device of item 2 above, characterized in that the magnets are reversely charged to minimize magnetic leakage. 8. According to item 2 above, the magnet is floating between the center pole and the coil to prevent mechanical vibrations from being transmitted to the housing and base plate assembly. device to do. 9. an actuator base, a movable carriage, means for mounting a transducer on said carriage for accessing a storage disk, means mounted on said base for guiding reciprocating linear movement of said carriage, and said carriage; and an electromagnetic means for linearly reciprocating the assembly and positioning the assembly in a read/write position with respect to a storage disk, the electromagnetic means comprising: a) a pair of spaced apart a magnet assembly, each magnet assembly having a central pole member, an annular cylindrical magnet surrounding the central pole member, and a magnet assembly secured to the base and spaced from an external surface of the magnet; a) a pair of external pole structures substantially surrounding the magnets and defining an air gap therebetween; a pair of cylindrical coils capable of freely reciprocating motion; C) means for forming slots in each of said external pole structures, said slots being opposed to each other; and d) connecting said carriage to said coils. and means extending through said slot to do so. 10. In the above item 9, the pair of external pole structures are formed integrally with each other, and the carriage and the transducer attached to the carriage move penetratingly toward the disk surface. An actuator having an integral forward end pole member having a hole drilled therein to allow for a. 11. In the above item 10, the attachment/detachment device is attached to the external pole structure and has a hole bored therein to allow movement of a portion of the carriage when the carriage moves in a direction away from the disk surface. An actuator having a freely movable rear end pole member. 12. In paragraph N9 above, the external pole structure is C
An actuator, characterized in that the open portions of the C-shape face each other and form the slot.