GB2302126A

GB2302126A - Locking mechanism for a personal computer

Info

Publication number: GB2302126A
Application number: GB9511851A
Authority: GB
Inventors: Gary Raymond Staines
Original assignee: COMPUSAFE Ltd
Current assignee: COMPUSAFE Ltd
Priority date: 1995-06-12
Filing date: 1995-06-12
Publication date: 1997-01-08
Also published as: GB9511851D0

Abstract

A locking mechanism for inhibiting the opening of a personal computer of the type having a chassis, a cover slidable relative to the chassis and retaining screws engaging in the chassis to hold the cover in its closed position, comprises two locking screws 44, 46 for engaging in the chassis of the computer in place of two of the retaining screws holding the cover in its closed position, a radially extending lever 40, 42 fast in rotation with the head of each locking screw 44, 46 and means 56 for locking the two levers 40, 42 to one another to prevent them from being rotated relative to the chassis of the computer.

Description

Locking Mechanism for a Personal Computer Field of the invention The present invention relates to a method and a locking mechanism for preventing unauthorised tampering with the interior of a personal computer.

Background of the invention Theft of personal computers (PC's) is becoming increasingly common and various locks have been proposed to prevent the removal of computers from premises. For example, locks are known that comprise a cable of which one end is securely fastened to the casing of the computer and the other end is secured by a padlock to a wall or a desk. While such a lock may inhibit removal of a computer it does not prevent a thief opening the casing of the computer and stealing valuable circuit components from its circuit board. Because of the cost of memory chips and processors, theft of such components is becoming increasingly common. A particular problem is that such theft can be carried out by an employee of a company and if, for example, only memory chips are removed, then the theft may go undetected for some time.

ObJect of the invention The present invention therefore seeks to provide a locking mechanism for inhibiting opening of the casing of a personal computer, the mechanism being easy to fit but difficult to remove when locked without causing severe and noticeable damage to the casing of the computer.

Summary of the invention According to a first aspect of the invention, there is provided a method of inhibiting the opening of a personal computer of the type having a chassis, a cover slidable relative to the chassis and retaining screws engaging in the chassis to hold the cover in its closed position, the method comprising removing two of the retaining screws holding the cover in its closed position, replacing each of the two screws by a respective locking screw the head of which is fast in rotation with a radially extending lever, and locking the two levers to one another to prevent the locking screws from being rotated relative to the chassis.

Preferably, each of the levers is formed with an elongate slot and the levers are locked to one another by aligning the slots with one another and placing a key operated lock in the aligned slots.

According to a second aspect of the invention, there is provided a locking mechanism for inhibiting the opening of a personal computer of the type having a chassis, a cover slidable relative to the chassis and retaining screws engaging in the chassis to hold the cover in its closed position, the mechanism comprising two locking screws for engaging in the chassis of the computer in place of two of the retaining screws holding the cover in its closed position, a radially extending lever fast in rotation with the head of each locking screw and means for locking the two levers to one another to prevent them from being rotated relative to the chassis of the computer.

The locking screws are preferably self-tapping screws of larger size than the retaining screws that they replace but alternatively the locking screws may be bolts for engaging in captive nuts mounted on the chassis of the computer.

Conveniently, the ends of the levers remote from the screws may be formed with elongate slots for receiving a keyoperated lock for preventing rotation of the levers after they have been fitted to the chassis of the computer.

The levers are preferably permanently secured to the locking screws, for example by welding, but it is alternatively possible for the screws to be initially separate and to have a non-circular head received in a matching recess formed in the lever so that when fitted to the computer the locking screw and the lever rotate together.

A spacer may conveniently be provided at the top of each locking screw to space the levers from the cover of the computer. Such a spacer may be formed separately from the lever but it is preferred that it too should be welded to the lever in order to simplify assembly and prevent its accidental loss. The spacers on the two levers are conveniently of different heights to allow for the thickness of the levers.

Brief description of the drawings The invention will now be described further, by way of example, with reference to the accompanying drawings, in which : Figure 1 is a perspective rear view of a personal computer with its cover partially removed, Figure 2 shows a locking mechanism of the invention, Figure 3 shows the locking mechanism of Figure 2 when fitted with a key-operated lock, and Figure 4 shows one half of an alternative embodiment of the locking mechanism of the invention.

Detailed description of the Dreferred embodiments Figure 1 shows a rear view of a tower casing of a personal computer having a chassis 10. The rear of the chassis has various connectors, amongst them a recessed plug 20 for receiving a mains supply socket, a socket 22 for a lead supplying mains power to a monitor, multi-pin connectors 24 and 26 for a keyboard and a mouse and various expansion slots 28 for receiving cards that may have a wide variety of connectors on them, amongst them connectors for the monitor, for peripherals such as printers and scanners and so on.

Also mounted on the rear of the chassis is a fan 34 for cooling the interior of the computer.

Inside the computer, there are mounted on the chassis various circuit boards, a power supply unit, and drive units all of which are accessible only after removal of a cover 12. The cover 12 is held on the chassis 10 by means of retaining screws 14 that pass through holes 32 in the casing and engage in holes 30 in the chassis. The cover 12 can slide relative to the chassis 10 in the manner shown in Figure 1 only after the retaining screws 14 have been removed.

The present invention is equally applicable to desk top casings in which the cover can slide forwards, rather than backwards, after the retaining screws have been removed.

To prevent unauthorised removal of the cover 12 and restricting access to the interior of the computer to authorised personnel, the invention provides a locking mechanism, shown in Figures 2 and 3, that it fitted in place of one pair of opposed retaining screws 14, preferably the top pair.

The locking mechanism is formed of two levers 40 and 42 each having welded to it at one end a self-tapping screw 44, 46 and a spacer 48, 50. The other end of each lever is formed with an elongate slot 52, 54. As seen in Figure 3, the spacer 48 is higher than the spacer 50.

Each lever 40, 42 is used to drive its screw 44, 46 in place of the retaining screw 14 removed from the rear of the computer. The screws 44 and 46 are self-tapping and slightly larger than the retaining screws 14 so that they grip the chassis 10 very firmly. After the screws 44, 46 have been driven firmly home, the levers are parked in the position shown in Figure 3 in which the slots 52, 54 are aligned with one another. A key-operated lock 56 is then inserted into the aligned slots 52, 54. The outer casing of the lock 56 has a portion that is received with the slot 52 so that the body of the lock cannot be rotated after it has been fitted to the levers 40, 42. The lock 56 also has a bar 58 that turns with the barrel of the lock when the correct key is inserted. The bar 58 can thus be rotated by key between a position in which it can pass through the aligned slots 52, 54 and a locked position in which it lies at right angles to the slots 52, 54, as illustrated.

The slots 52 and 54 are elongated to allow for computer casings of different widths. As an alternative to an elongate slots, it would be possible to use a series of holes. One can also employ different types of lock from the lock illustrated, for example a padlock or a shackle lock.

Without the use of considerable force, the locking mechanism of the invention cannot be removed from the casing of the computer, and while it is in place the computer cannot be opened. Of course, a determined thief will eventually be able to break into the casing but the time that this would take itself offers a significant deterrent. Should the thief succeed in breaking into the computer, then there will be considerable damage to the casing of the computer and the theft will not go undetected.

It will be appreciated that various modifications may be made to the described locking mechanism. For example, bolts may be used in place of self-tapping screws and these may engage in captive nuts on the computer chassis.

Furthermore, the screws and the spacers may be formed separately from the levers provided always that locking of the levers to one another will prevent the locking screws from being turned.

The embodiment of Figure 4, the lever 60 includes a step 60 and its end 62 containing an elongate slot 68 lies in a plane normal to the part of the lever 60 welded to the screw 66. This embodiment does not require spacers because the ends 62 of the levers 60 will face each other instead of lying one above the other. The purpose of the step 64 is to permit the twisted end 62 of the lever to clear the casing of the computer as the screw 66 is driven into the computer chassis. This step 64 may be omitted if a spacer is fitted to the top of the screw, as in the previously described embodiment.

The primary purpose of the locking mechanism of the invention is to prevent the casing of the computer from being opened but the elongate slots in the levers and the lock fitted to them also provide a suitable anchoring for a chain or cable securing the computer to a wall or a desk.

Such an anchoring is more secure than the industrial adhesives used previously for chaining a computer to a wall or a desk and has the advantage of being removable without damage to the casing of the computer.

Claims

1. A method of inhibiting the opening of a personal computer of the type having a chassis, a cover slidable relative to the chassis and retaining screws engaging in the chassis to hold the cover in its closed position, the method comprising removing two of the retaining screws holding the cover in its closed position, replacing each of the two screws by a respective locking screw the head of which is fast in rotation with a radially extending lever, and locking the two levers to one another to prevent the locking screws from being rotated relative to the chassis.

2. A method as claimed in claim 1, wherein each of the levers is formed with an elongate slot and the levers are locked to one another by aligning the slots with one another and placing a key-operated lock in the aligned slots.

3. A locking mechanism for inhibiting the opening of a personal computer of the type having a chassis, a cover slidable relative to the chassis and retaining screws engaging in the chassis to hold the cover in its closed position, the mechanism comprising two locking screws for engaging in the chassis of the computer in place of two of the retaining screws holding the cover in its closed position, a radially extending lever fast in rotation with the head of each locking screw and means for locking the two levers to one another to prevent them from being rotated relative to the chassis of the computer.

4. A locking mechanism as claimed in claim 3, wherein the locking screws are self-tapping screws of larger size than the retaining screws that they replace.

5. A locking mechanism as claimed in claim 3, wherein the locking screws are bolts for engaging in captive nuts mounted on the chassis of the computer.

6. A locking mechanism as claimed in claim 3, 4 or 5, wherein the ends of the levers remote from the screws are formed with one or more apertures for receiving a keyoperated lock for preventing rotation of the levers after they have been fitted to the chassis of the computer.

7. A locking mechanism as claimed in claim 6, wherein the levers are each formed with a single elongate aperture.

8. A locking mechanism as claimed in any of claims 3 to 7, wherein the levers are permanently secured to the locking screws.

9. A locking mechanism as claimed in any of claims 3 to 7, wherein the locking screws are initially separate from the levers and have a non-circular head received in a matching recess formed in the lever so that when fitted to the computer the locking screw and the lever rotate together.

10. A locking mechanism as claimed in one of claims 3 to 9, wherein a spacer is provided at the top of each locking screw to space the lever from the cover of the computer.

11. A locking mechanism as claimed in claim 10, wherein the spacers are welded to the levers.

12. A locking mechanism as claimed in claim 10 or 11, wherein the levers are flat and the spacers on the two levers are of different height.

13. A locking mechanism as claimed in any of claims 3 to 9, wherein each lever is twisted along its length through 900 whereby the ends of the levers that are locked to one another lie in a plane normal to the other ends of the levers.

14. A locking mechanism constructed, arranged and adapted to operate substantially as herein described with reference to and as illustrated in the accompanying drawings.