Tuned Shock Absorbing System for Portable Computer Hard Disc Drives

The disclosures herein relate generally to portable computer hard disc drives and more particularly to an impact shock absorbing mounting apparatus and method for such hard drives.

Hard disc drives are one of the most common sources of field failures in computers. Within a hard disc drive housing are several thin glass discs, i.e., magnetic media, each having an associated flying head. Thus, hard disc drives are one of the most fragile components of the computer in terms of sensitivity to impact. This is particularly true in cases where a major component of the impact forces is normal to the surface of the hard drive media. Hard disc drives are more sensitive in this orientation because there is opportunity for the read heads to come into physical contact with, and cause damage to the discs.

Upon impact, the heads bounce and contact the discs. The discs may be either broken or scored by such impact. Loose particles may also result from such impact which are free to move around inside the hard disc drive cassette and contact other parts of the drive thus causing new failures. Furthermore, such impacts cause shock to the entire hard disc drive cassette, not just to the heads.

Attempts to cushion the drives against shock from impact have produced elastomer feet in the bottom or rest surface for a cushioning effect of the portable computer housing on its associated rest surface. These feet also serve as friction surfaces to limit lateral movement of the portable computer relative to its rest surface. Cushioned mounts placed within the computer housing provide vibration damping but have not addressed the issue of where such mounts should be located to provide maximum protection from impact shocks. This is an important oversight since protection from the forces from impact shocks require an entirely different solution than protection from vibration.

Therefore, what is needed is a method and apparatus for providing cushioned impact shock protection for hard disc drives in portable computers which protection is strategically located to substantially reduce damage from impact forces acting normal to the bottom surface of the portable computer housing.

One embodiment, accordingly, provides impact shock protection for hard disc drives in portable computers. To this end, a computer system includes a chassis and a circuit board mounted in an elevated position on mounts provided within the chassis. A space is defined between the board and the chassis. A shock absorbing device extends in the space between the board and the chassis and is spaced from the mounts for limiting flexure of the board toward the chassis in response to impact from forces acting on the computer.

A principal advantage of this embodiment is that impact shock protection in portable computers is greatly enhanced which substantially reduces damage from impact forces acting normal to the bottom surface of the portable computer housing.

FIG. 1 is a diagrammatic view illustrating an embodiment of a computer system.

FIG. 2 is an isometric view illustrating an embodiment of a portable computer.

FIG. 3 is an isometric view illustrating an embodiment of a portable computer chassis.

FIG. 4 is a partial side view diagrammatically illustrating an embodiment of a hard drive shock absorbing device.

FIG. 5 is a partial side view diagrammatically illustrating an alternative embodiment of a hard drive shock absorbing device.

FIG. 6 is a partial side view diagrammatically illustrating another alternative embodiment of a hard drive shock absorbing device.

FIG. 7 is a partial side view diagrammatically illustrating still another alternative embodiment of a hard drive shock absorbing device.

FIG. 8 is a partial side view diagrammatically illustrating a further alternative embodiment of a hard drive shock absorbing device.

In one embodiment, a computer system 41, FIG. 1, includes a microprocessor 11 which is connected to a bus 13. Bus 13 serves as a connection between microprocessor 11 and other components of computer system 41. An input device 15 is coupled to microprocessor 11 to provide input to microprocessor 11. Examples of input devices include keyboards, touchscreens, and pointing devices such as mouses, trackballs and trackpads. Programs and data are stored on a mass storage device 17 which is coupled to microprocessor 11. Mass storage devices include such devices as hard disks, optical disks, magneto-optical drives, floppy drives, ROMs and the like. Computer system 41 further includes the display 19 which is coupled to microprocessor 11 by a video controller 21. A system memory 23 is coupled to microprocessor 11 to provide the microprocessor with fast storage to facilitate execution of computer programs by microprocessor 11. It should be understood that other busses and intermediate circuits can be deployed between the components described above and microprocessor 11 to facilitate interconnection between the components and the microprocessor.

Referring to FIG. 2, illustrated is a portable, notebook size computer designated 10 including the self-contained computer system 41, FIG. 1. Computer 10, FIG. 2, includes a hinged top or lid 12 including display 19 rotatable about a pivotal member 14 from a nested position "N", with a horizontal base 16, to a substantially vertical position "V".

In FIG. 3, computer 10 includes a chassis 25 formed of a suitable plastic material and having a hard disc drive 18 mounted therein. Chassis 25, FIG. 4, includes mounts 20 spaced apart and located adjacent the periphery of a printed circuit (PC) board 22. A plurality of mounting screws 27 are commonly used to secure PC board 22 on the mounts 20. Although only two of such mounts 20 are shown, there are preferably provided one mount 20 at each of the four corners of PC board 22.

Mounts 20, FIG. 4, support PC board 22 in an elevated position above a portion of chassis 25 such that a space 24 is defined between PC board 22 and chassis 25. A plurality of components including SIMM connectors 26 are mounted on a surface 30 of PC board 22 so that the connectors extend into space 24. Due to the mounting arrangement of PC board 22 on spaced apart mounts 20, PC board 22 spans space 24 between mounts 20. This results in an unsupported expanse 28 of PC board 22 bridging the space 24 between mounts 20 which is subject to flexure.

Hard disc drive 18 is mounted on a surface 32 of PC board 22 along the expanse 28. An external bottom or rest surface 34 of chassis 25 includes a skid foot 36. Typically, a skid foot 36 is provided at each of the four corners of chassis 25. The purpose of the skid foot 36 is two-fold. First, skid foot 36 may be formed of an elastomer which provides some shock protection when rest surface 34 impacts an adjacent support surface 38. Second, skid foot 36 provides a frictional engagement between computer 10 and surface 38 which helps stabilize computer 10 and resists lateral movement of computer 10 on surface 38.

As a result of this construction, should computer 10 be dropped so that surface 34 including skid feet 36 impact support surface 38, a major component of the resulting initial impact force F1 acts downwardly toward and normal to surface 38. Skid feet 36 absorb very little of such impact force. Expanse 28 of board 22 momentarily flexes into space 24 a sufficient amount to permit the board 22, SIMM connectors 26 or other components to contact or "slap" against an internal surface 40 of chassis 25. In addition, external surface 34 of chassis 16 can flex between skid feet 36 and "slap" against support surface 38. Reaction or secondary impact forces F2 then act in the opposite direction, or upwardly toward and normal to hard disc drive 18. Such initial and secondary forces impose high shock loads on the hard disc drive 18 and its internal components, causing severe damage to the discs and flying heads (not shown). In addition, when expanse 28 of board 22 flexes into space 24, it momentarily flexes away from hard disc drive 18 and then returns to engage the hard disc drive 18 and force the hard disc drive 18 in an upward direction to impact with an upper surface (not shown) of chassis 25.

A benefit of the embodiments described herein is that such shock loads can be substantially limited in their damaging effect on hard disc drive 18. This is accomplished by providing means such as a shock absorbing device generally designated 42, positioned to extend in space 24 between PC board 22 and chassis 25. Shock absorbing device 42 is spaced from mounts 20 for limiting flexure of expanse 28 toward chassis 25 in response to impact forces acting on computer 10.

In FIG. 4, shock absorbing device 42 includes at least one rigid member 44 formed of a plastic material and attached to or formed with chassis interior surface 40 and extending therefrom toward PC board 22. Rigid member 44 may extend to contact expanse 28 of board 22 or may contact a board component such as SIMM connector 26. In addition to rigid member 44, a resilient shock foot member 48, FIG. 4, is mounted on exterior surface 34 of chassis 16 adjacent skid foot 36. Furthermore, shock foot member 48 is aligned with rigid member 44. FIG. 5 illustrates that rigid member 44 may include a resilient cap member 46 which contacts expanse 28 or board component 26 to enhance the shock absorbing ability of rigid member 44. Rather than adding shock foot member 48, it is optionally possible to move skid foot member 36 to a position directly aligned with rigid member 44, FIG. 5. Thus, instead of having both a skid foot member 36 and a shock foot member 48, the skid foot member 36 can serve a dual purpose.

In FIG. 6, shock absorbing device 42 includes a plurality of rigid members 44a formed of plastic material and attached to or formed with chassis interior surface 40 and extending therefrom toward PC board 22. Rigid members 44a may extend to contact expanse 28 of board 22 or may contact a board component such as SIMM connector 26. FIG. 7 illustrates that rigid members 44a may include a resilient cap member 46a which contacts expanse 28 or board component 26 to enhance the shock absorbing ability of rigid members 44a.

In FIG. 8, shock absorbing device 42 includes a resilient member 44b formed of a suitable elastomer and mounted on interior surface 40 of chassis 25 so as to extend therefrom toward PC board 22. Resilient member 44b may extend to contact expanse 28 of board 22 or may contact a board component such as SIMM connector 26.

As it can be seen, the principal advantages of the shock absorbing system for hard disc drives, according to the embodiments disclosed herein, are that it provides a method and apparatus for providing cushioned impact shock protection for hard disc drives in portable computers. The protection afforded thereby is strategically located to substantially reduce damage from impact forces acting normal to the bottom surface of the portable computer housing.

Although illustrative embodiments have been shown and described, a wide range of modifications, change and substitution is contemplated in the foregoing disclosure and in some instances, some features of the embodiments may be employed without a corresponding use of other features. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the embodiments disclosed herein.