GB2226706A

GB2226706A - Disc drive mounting

Info

Publication number: GB2226706A
Application number: GB8829736A
Authority: GB
Inventors: Michael David Fischer
Original assignee: Research Machines PLC
Current assignee: Research Machines PLC
Priority date: 1988-12-21
Filing date: 1988-12-21
Publication date: 1990-07-04
Anticipated expiration: 2008-12-21
Also published as: GB8829736D0; GB2226706B

Abstract

A mounting for securing a disc drive unit (1) directly to a potentially distorted parent component, such as the chassis (10) of a microcomputer, the mounting comprising at least three, non-linear mounting means, eg mounting holes (11, 12, 14) in the parent component, at least one (14) of which is positioned in a resilient portion (15) of the parent component, such that when mounting means of the disc drive unit (1) are secured to those of the parent component any distortion in the parent component is at least partially accommodated by flexure of the resilient mounting means (14, 15) rather than being transmitted to the disc drive unit (1). <IMAGE>

Description

DISC DRIVE MOUNTING This invention relates to a mounting for securing a disc drive unit such as that of a microcomputer to a potentially distorted parent component.

Disc drives are now widely used in microcomputers and technical improvements in the performance of microcomputers has led disc drive manufacturers to produce disc drives that can store greater amounts of information. In addition, there is a continual requirement to reduce the size of the disc drive leading to further increases in the storage density used.

Disc drive manufacturers supply disc drive units with standard mounting connections, usually in the form of threaded holes in the chassis of the disc drive unit, as shown in Figure 1(A5. Four threaded holes 2 are usually provided on one face, eg the underside, of the disc drive chassis and two threaded holes 3 in opposite ends of the chassis. The chassis of the disc drive unit is typically made of aluminium or a zinc diecasting. The disc drive unit 1 is secured to a parent component 4, such as a chassis of the microcomputer, by screws 5 engaging with the threaded holes.This is typically done by screwing one face of the disc drive unit 1 to the parent component 4 using the four threaded holes 2 as shown in Figure 1(B) or by securing the disc drive unit 1 between two portions of the parent component 4 by means of the two threaded holes 3 provided in each end of the unit as shown in Figure 1(C).

Problems have, however, arisen with this form of mounting as any distortion or deformation in the parent component is transmitted to the disc drive chassis as the screws are tightened to secure it in place. This distortion of the disc drive chassis can cause misalignment of the read/write head(s) of the unit and with the high storage densities now being used, this can give rise to serious problems.

For instance, in a typical 3#" disc drive unit, the read/write heads are designed to be positioned with an accuracy of around 15 microns to read and write data to the closely spaced tracks on a floppy disc. The level of distortion typically arising in the chassis of a microcomputer due to manufacturing tolerances may be anything up to 0.3mum and much of this is transmitted to the disc drive chassis when it is secured thereto. Accurate measurement indicates that this can cause head misalignment in excess of 15.2 microns, the failure limit.

Two main approaches have been adopted to overcome the transmission of external stress to the disc drive unit. The first is to manufacture the parent component to a higher degree of accuracy to reduce the level of distortion. This is not a preferred option as it tends to increase the cost of the parent component.

The other option has been to use an intermediary mounting component between the disc drive unit and the parent component. The intermediary component is designed to be secured to the disc drive by mounting screws engaging the threaded holes provided therein. The intermediary component is then mounted to the parent component so that any distortion is accommodated by flexure of the intermediary component and/or taken up by play within its mounting to the parent component.

This method also has disadvantages as the use of an intermediary component again increases the complexity and cost due to the provision of the component itself and the additional assembly costs involved in fitting it and requires additional space within the microcomputer. The use of such additional components also conflicts with the trend in microcomputers towards increased performance with a decrease in size. In addition, experience has shown that an unacceptable degree of distortion is still transmitted to the disc drive unit unless a very loose mounting between the intermediary component and the parent component is provided.

Examples of two conventional mountings using an intermediary component are shown in Figures 2 and 3. Figure 2(A) shows a disc drive unit with a plastics drive rail 6 secured to each end by screws engaging the holes 3 (see Figurel) in opposite ends of the unit. This assembly is then mounted to the parent component by sliding the rails 6 into channels provided in the parent component 4 as shown in Figure 2(B) to provide a loose clearance within the channels so allowing the disc drive unit to remain stress free.

Figure 3(A) shows a disc drive unit 1 and a non-rigid intermediary chassis 7, for instance formed from a plastics moulding. The chassis is secured to the underside of the disc drive unit 1 by screws engaging the holes 2 (see Figure 1) provided in the underside thereof. The intermediary chassis 7 is then mounted to the parent component by engaging tabs 8 provided thereon with slots on the parent component provided by upstanding brackets 9 as shown in Figure 3(B) so the intermediary chassis 7 is allowed to 'float' on the parent component.

The level of distortion transmitted to the disc drive using such mountings has been reduced but the increased storage densities now used require a corresponding decrease in the level of distortion transmitted, There is also a need for accurate location of the disc drive unit with respect to the parent component so that the front panel of the disc drive unit fits accurately in an aperture provided in a microcomputer and through which the unit is accessed. With a relatively loose fitting between the intermediary component and the parent component this is difficult to achieve. Even with the conventional rigid mounting, it was necessary to partially tighten the mounting screws and then align the disc drive unit with an accurate jig before being secured in place to ensure it was accurately positioned.

The present invention aims to provide a simple but effective mounting for limiting the transmission of distortion from the parent component to the disc drive unit and which avoids the difficulties discussed above.

Thus, according to the invention, there is provided a mounting for securing a disc drive unit directly to a potentially distorted parent component, the mounting comprising at least three, non-linear mounting means on the parent component, at least one of which is of a resilient nature, such that when mounting means of the disc drive unit are secured to the said mounting means of the parent component any distortion in the parent component is at least partially accommodated by flexure of the resilient mounting means rather than being transmitted to the disc drive unit.

Preferred features of the invention will be apparent from the following description and the subsidiary claims of the specification.

The invention will now be further described, merely by way of examples, with reference to the accompanying drawings, in which: Figures 1(A), (B) and (C) show a disc drive unit with the standard mounting holes provided therein; Figures 2 (A) and (B) show a conventional mounting using an intermediary component in the form of a disc drive rail; Figures 3(A) and G) show another conventional mounting using an intermediary component in the form of a non-rigid chassis; Figures 4(A) and (B) show a first embodiment of a mounting according to the invention; Figures 5(A) and (B) show a second embodiment of a mounting according to the invention; Figures 6(A) and (B) show a third embodiment of a mounting according to the invention; and Figures 7(A), (B) and (C) show a fourth embodiment of a mounting according to the invention.

The mounting holes provided in a disc drive unit and the conventional mountings shown in Figures 2 and 3 have been described above during the discussion of the prior art.

The following description is given with reference to the orientation of the disc drive units shown in the drawings. It should, however, be appreciated that these can be positioned in a variety of other orientations as is common in the art and the orientation of the mounting used therewith will thus also be altered accordingly.

A first embodiment of a mounting according to the invention is shown in Figures 4 (A) and (B). In the arrangement shown, the disc drive unit 1 is to be secured with its underside adjacent part of a sheet metal chassis 10 a microcomputer where the assembly can be accessed from below. In this arrangement, first and second mounting holes 11 and 12 are provided on the chassis 10 for securing the disc drive unit 1 thereto by means of screws 13 engaging with threaded holes 2 (see Figure 1) in the underside of the disc drive unit 1. The two holes 11 and 12 constitute substantially rigid mounting means similar to those used in conventional arrangements.A third mounting hole 14 is, however, provided in a resilient portion of the chassis 10 which comprises a tongue 15 separated on three sides from the remainder of the chassis but integral therewith along its fourth side. The tongue 15 is thus able to flex out of the plane of the surrounding portion of the chassis 1 by bending about its Join therewith along its fourth side. The disc drive unit 1 is secured to the tongue 15 by a screw 16 passing through the mounting hole 14 and engaging a further hole 2 in the underside of the unit 1.

Any distortion of the chassis 1 between the mounting holes 11 and 12 and the mounting hole 14 in a direction perpendicular to the plane of the chassis 1 will thus be at least partially accommodated by flexure of the tongue 15 as the screws 13 and 16 are tightened rather than being transmitted to the disc drive unit 1. It is thus the chassis, or parent component, which is distorted rather than the disc drive unit so the disc drive unit remains in a sun unstressed condition. Figure 4(B) shows a side view of the disc drive unit 1 when secured to the chassis 10 in this arrangement in which the three mounting means are substantially co-planar.

Figures 5(A) and O) show a similar arrangement to Figure 4 except that first and second mounting holes 17 and 18 are provided in upstanding portions 19 and 20 of the chassis 1 which are substantially perpendicular to the adjoining potion of the chassis 10 for securing to mounting holes 3 provided in one end of the disc drive unit 1. The upstanding portions 19 and 20 of the chassis may be of a resilient nature similar to the tongue 15 in which case they are able to flex so as to accommodate any distortion of the chassis 1 between the holes 17 and 18 and the tongue 15 in a direction parallel to the plane of the chassis 1. Alternatively, the portions 19 and 20 may be substantially rigid. As shown in Figure 5(A), the upstanding portions 19 and 20 are secured to the mounting holes 3 by screws 21 fitted from the side.This arrangement is thus suitable where access to the underside of the disc drive unit is restricted. Figure 5(B) is a side view of the disc drive unit 1 when secured to the chassis 10 in this arrangement.

Figures 6 (A) and (B) show an arrangement for securing a disc drive unit 1 in a raised position on a chassis 22 formed from a plastic moulding. The mounting comprises a first mounting hole 23 in a substantially rigid pedestal 24 and second and third mounting holes 25 and 26 in raised limbs 27 and 28 pressed out of the chassis. The underside of the disc drive unit 1 is secured to the pedestal 24 and the limbs 27 and 28 by screws 29 which engage holes 2 (see Figure 1) in the underside of the disc drive unit 1.

Each of the limbs 27 and 28 is of a resilient nature and able to flex in a direction perpendicular to the plane of the chassis 22. A third limb 30 is provided to support the underside of the disc drive unit 1 but is not secured thereto.

It will be appreciated that in this arrangement, it is necessary to provide at least one rigid mounting means, such as the pedestal 24, for setting the height at which the disc drive unit 1 is mounted above the plane of the chassis 22. In an alternative arrangement (not shown), the mounting may comprise two rigid pedestals and one resilient limb together with an optional supporting limb. Figure 6(B > is a side view of the disc drive unit 1 when secured to the chassis using the arrangement shown in Figure 6(A).

Figures 7(A), (B) and (C) show an arrangement similar to that of Figure 5 but with a chassis formed from a plastics moulding. In this case, an upstanding portion 31 of the chassis is provided with slots 32 and 33 for receiving screws 34 and 35 pre-installed within mounting holes 3 provided in one end of the disc drive unit 1. The slots 32 and 33 are L-shaped so that the screws 34 and 35 can be positioned therein as the disc drive unit 1 is lowered into position and the unit is located and firmly held in place as the screws are slid forwards in the slots. The movement of the disc drive unit 1 during this installation procedure is illustrated by the arrow A shown in Figure 7 (A).

The slot 32 is also provided with a resilient arm or latch 36 which forms a snap-action securement device to lock the disc drive unit 1 in position once the screw 34 has been moved to the ends of the slot. As the screw 34 is lowered into the slot 32 it displaces the arm 36 downwards to a position shown by dotted lines in the Figure. With the arm 36 in this position, the screw 34 can be moved forward towards the end of the slot 32. As it reaches the end of the slot 32, it slides off the end of the arm 36 which then snaps back into position and thus prevents the screw 34 from moving back along the slot 32. The disc drive unit cannot therefore be removed without displacing the arm 36 upwards to release the screw 34. As in the arrangement shown in Figure 5, the upstanding portion 31 may be substantially rigid or may be of a resilient nature.

The plastics moulding in this arrangement is provided with a resilient tongue 37 corresponding to that shown in Figure 5(A). However, the tongue 37 is provided with a key-hole shaped mounting hole 38 for receiving and locating a screw 39 which has been secured within a mounting hole 2 (see Figure 1) in the underside of the disc drive unit 1. As the disc drive unit 1 is lowered into place, the screw 39 is positioned within the broad end of the hc.le 38 and then, as the disc drive unit 1 is slid forwards towards the front of the microcomputer, the screw 39 is slid into the narrower end of the hole 38 to accurately locate the disc drive unit 1. The underside of the tongue 37 may be tapered as shown in the side view in Figure 7(C) so the screw 39 is locked in position as it is slid forwards from the position shown in dotted lines to that shown in solid lines in the Figure.

The plastics chassis is preferably moulded in one piece incorporating the upstanding portion 31, with the arm 36, and the resilient tongue 37. Figure 7(B) shows a side view of disc drive unit 1 when secured to the chassis is this arrangement.

Each of the arrangements described above comprises three, non-linear mounting means supporting three extremities of a disc drive unit. At least one of the mounting means is of a resilient nature and, preferably, at least one is of a substantially rigid nature. The mounting may thus comprise three mounting means one or two of which are of a resilient nature and one or two of which are of a substantially rigid nature. An additional support is preferably provided for the fourth extremity of the disc drive unit.

This may comprise a portion of the chassis lying adjacent the underside of the disc drive unit as in the arrangements shown in Figures 4, 5 and 7 or may comprise an additional support such as the limb shown in Figure 6.

Unless the fourth support is of a resilient nature, it is preferably not secured to the disc drive unit as it it desirable to provide a maximum of only two rigid mounting means secured to the unit otherwise further 4 distortion can arise if the respective mounting means cannot all be exacty aligned with each other.

With mountings such as those described above, test have shown that the stress transferred to the disc drive unit is so small that head misalignment is negligible. The disc drive unit can also be accurately aligned with an aperture in the microcomputer wihout the need for a jig, with the parent component manufactured to industry standard tolerances, since accurate positioning of the mounting holes provides an inherently accurate location for the unit.

The compliant mounting has also been found to reduce the susceptibility of the disc drive unit to shock compared to conventional rigid mountings.

It will also be appreciated that the type of mounting described eliminates the need for additional components and thus avoids the increase in cost and assembly time this entails. The mountings described also require no more space beyond that required by a conventional rigid mounting.

As demonstrated, in particular by the arrangement shown in Figure 7, the type of mounting described above also lends itself to rapid assembly technlques. With the clip-in mounting shown, the disc drive can be mounted on the parent component without any tools within 3 - 4 seconds compared to about 15 seconds for conventional mountings. The disc drive unit is also easy to service as it can be removed or replaced quickly end easily.

With such rapid assembly mountings, alignment of the disc drive unit is also automatic. Conventional mountings require clearance holes for the screws and this leads to misalignment of the front of the disc drive unit with the front panel of the microcomputer in which it is installed.

Claims

1. A mounting for securing a disc drive unit directly to a potentially distorted parent component, the mounting comprising at least three, nonlinear mounting means on the parent component, at least one of which is of a resilient nature, such that when mounting means of the disc drive unit are secured to the said mounting means of the parent component any distortion in the parent component is at least partially accommodated by flexure of the resilient mounting means rather than being transmitted to the disc drive unit.

2. A mounting as claimed in claim 1 in which the resilient mounting means comprises a mounting hole provided within a portion of the parent component which is able to flex relative to the neighbouring portions thereof.

3. A mounting as claimed in claim 2 in which the resilient mounting means comprises a tongue cut or pressed out of the surrounding portion of the parent component.

4. A mounting as claimed in any of claims 1, 2, or 3 in which at least one of the mounting means on the parent component is of a substantially rigid nature.

5. A mounting as claimed in claim 4 in which the substantially rigid mounting means comprises a mounting hole provided in substantially rigid portion of the parent component.

6. A mounting as claimed in any preceding claim in which the three mounting means are substantially co-planar so as to be arranged for the securement to mounting means provided on one side of a disc drive unit.

7. A mounting as claimed in claim 6 in which the three mounting means are raised from the plane of the adjoining portions of the parent component.

8. A mounting as claimed in any of claims 1 to 5 in which one of the three mounting means is provided in a first plane and the other two are provided in a plane substantially perpendicular thereto so as to be arranged for securement to mounting means provided on one side and one end of a disc drive unit.

9. A mounting as claimed in any preceding claim in which one or more of the mounting means comprises a hole shaped to receive and engage the head of a screw or similar device secured to a disc drive unit.

10. A mounting as claimed in claims 2 and 9 in which the resilient mounting means comprises a mounting hole provided in the said portion of the parent component which is able to flex relative to the neighbouring portions thereof and in which the mounting hole has a broad portion for receiving the head of the screw or similar device and a narrow portion for engaging the screw or similar device.

11. A mounting as claimed in claim 9 or 10 in which the said one or more of the mounting means is provided with a snap-action securement device for securing the screw or similar device once it is fully engaged within the mounting hole.

12. A mounting as claimed in any preceding claim in which the parent component comprises a chassis of a microcomputer.

i3. A disc drive unit when secured directly to a parent component by a mounting as claimed in any preceding claim.

14. A mounting substantially as hereinbefore described with reference to Figures 4 to 7 of the accompanying drawings.

Amendments to the claims have been filed as follows 1. A mounting for securing a disc drive unit directly to a potentially distorted parent component, the mounting comprising at least three, nonlinear mounting means integrally formed with the parent component, at least one of which is of a resilient nature, such that when mounting means of the disc drive unit are secured to the said mounting means of the parent component any distortion in the parent component is at least partially accommodated by flexure of the resilient mounting means rather than being transmitted to the disc drive unit.

2. A mounting as claimed in claim 1 in which the resilient mounting means 4 comprises a mounting hole provided within a portion of the parent component which is able to flex relative to the neighbouring portions thereof.

13. A disc drive unit when secured directly to a parent component by a mounting as claimed in any preceding claim.