GB2246164A

GB2246164A - Sliding fastener with tamper-evident locking

Info

Publication number: GB2246164A
Application number: GB9016003A
Authority: GB
Inventors: Arthur Michael Benjamins; Frank Henry Arthur
Original assignee: Envopak Group Ltd
Current assignee: Envopak Group Ltd
Priority date: 1990-07-20
Filing date: 1990-07-20
Publication date: 1992-01-22
Anticipated expiration: 2010-07-20
Also published as: GB2246164B; GB9016003D0

Abstract

A sliding fastener has means for tamper-evident locking in the closed position. A slider 2 is provided to close the sliding fastener 1. A disposable locking element 4 has means 5, 6 at one end for engagement with the slider. A cover 11 is arranged near the slider in the closed position and defines an opening through which an opposite end of the disposable locking element can be slidingly inserted by resilient deformation of part 9 thereof, but not slidingly retracted therefrom. Engagement of the disposable locking element with the slider and the cover prevents opening of the sliding fastener without rupture of the disposable locking element. As shown, rupture is carried out by pivoting the cover 11 and causing a peg 11A to break off the part 9. In other embodiments, the looking element 4 is retained on the slider by a key-like member (25, Figs. 9 & 10) and the locking element is ruptured by a twisting action (Figs. 14-16). <IMAGE>

Description

A LOCKING DEVICE This invention relates to a locking device, and more particularly to a device for locking a sliding fastener in tamper-evident fashion.

Our earlier British Patent No. 1 424 680 discloses a locking device which has been in commercial use with great success for several years. Figures 1 and 2 of the accompanying drawings show a preferred embodiment of locking device according to this prior patent.

According to this embodiment, a zip fastener 13 on a reusable envelope 10 can be locked in tamper-evident fashion, i.e. if it is unlocked by other than authorised personnel, such interference will be evident by damage to a disposable locking element 18. Upper and lower plates 19 and 20 are attached to the envelope 10 near the end of the zip. The closing mechanism 15 of the zip includes a slider 15 with pull tab 16 which, when the zip has been fastened, can lie flat over the upper plate 19, guided by upstanding lugs 19', a central hole in the tab 16 passing over a raised housing 23' integral with the upper plate 19. The housing 23' has a slot shaped entrance 22 for receiving a disposable locking element 18 of synthetic plastics material. The locking element has a plug part 29, joined by a stem part 28 with a narrow weakened section 31, to a head part 26.The plug part is of flat arrow-head formation with swept back barbs 30 which are resiliently deformable within the general planer-of the arrow-head to reduce the span of the barbs. This span in the non-deformed condition is slightly greater than the width of the entrance 22.

The plug part 29 can thus be pushed through the entrance 22 with inward deformation of the barbs 30, and after such insertion the barbs return to their original span.

Withdrawal of the plug part from the housing is then prevented by engagement between the barbs and the internal surface of the housing on each side of the entrance 22. The head part 26 remains outside the housing and lies flat on top of part of the pull tab 16, thereby preventing the pull tab from being lifted. The zip can then only be undone by breaking the locking element at the weakened section 31, thereby permitting the pull tab to be lifted.

We have sought to improve the above device. In the use of the above device, the disposable locking element has to be inserted into the housing when the zip is in the closed position and not before. In a typical office there may be a large number of such reusable envelopes which all have to be sealed at the end of the working day. It would therefore be advantageous if the disposable locking elements could be i"pre-loaded" in such a way that they would automatically be inserted into the housing on closing of the zip fasteners. This object is achieved by the present invention.

The present invention provides a sliding fastener having a device for tamper-evident locking in the closed position, comprising a slider to effect closing of the sliding fastener, a disposable locking element engagable at one end with the slider and resiliently deformable at an opposite end, and a cover member arranged near the closed position of the slider and defining an opening through which said opposite end of said disposable locking element is slidingly insertable by resilient deformation thereof but not slidingly retractable therefrom, whereby engagement of the disposable locking element both with the slider and with the cover member prevents opening of the sliding fastener without rupture of the disposable locking element.

In a preferred embodiment, the cover member is hingeable upwardly and includes an edge which presses against the disposable locking element and ruptures it during such upward hingeing.

Reference is now made to the accompanying drawings, in which: Figure 1 is a perspective view of a locking device according to British Patent No. 1 424 680 as already described; Figure 2 is a central longitudinal section of the locking device shown in Figure 1; Figure 3 is a plan view of a locking device according to a preferred embodiment of the present invention; Figure 4 is a side view corresponding to Figure 3 and partly in section; Figure 5 is a side view corresponding to Figures 3 and 4 and showing rupture of the disposable locking element; Figures 6, 7 and 8 correspond respectively to Figures 3, 4 and 5 and show an alternative embodiment of the invention; Figures 9 and 10 are perspective views and Figure 11 a part sectional side view of a further embodiment of the invention;; Figures 12 and 13 are respectively plan and side views of a still further embodiment of the invention; and Figures 14, 15 and 16 are transverse sectional views showing rupture of the disposable locking element in Figures 12 and 13.

Referring now to Figures 3 to 5, this shows a device for sealing a container such as a reusable envelope. A zip chain 1 is provided with a slider 2 which can close the zip in conventional fashion. The slider may be provided with a swinging pull tab 3.

A disposable locking element 4 is made of plastics material and is of generally flat rectangular shape.

One end of the disposable element includes a rounded shoulder 5 and slot 6. These parts cooperate with a rounded flange 7 and upstanding lug 8 on the slider, so that the disposable element can be press-fitted onto the slider. The disposable element is then held rigidly parallel with the line of the zip chain 1. This pressfitting can be done before the envelope is closed, i.e.

while the zip is in the fully open position. The zip can then be closed with the disposable element attached to the slider.

The end of the disposable element opposite to the shoulder 5 is provided with a pair of resilient, backwardly swept hooks 9. This end of the disposable element cooperates with a cover member 11. The cover member includes a central peg llA with an opening on either side. As the zip slider, with the disposable element mounted thereon, is moved to the closed position, the hooks 9 slide towards the peg llA, and are resiliently deflected to either side thereof, until the hooks have passed the peg. The hooks then resiliently return to their original shape, as shown in Figure 3, and sliding withdrawal of the disposable element from within the cover member is prevented. Thus, in this position, one end of the disposable element is engaged with the slider, and the other end is engaged with the peg. Furthermore, the cover member prevents unauthorised interference with the hooks, so that the zip can no longer be opened without rupture of the disposable element.

The cover member 11 is mounted on trunnions and can therefore hinge upwardly as shown in Figure 5. To assist such hingeing, the cover member is extended to form a handle 12. The cover member also has an underhanging part 14 to prevent unauthorised access to the hooks from the side. When the cover member is hinged upwardly, the edge thereof at 24 presses downwardly against the upper surface of the disposable element, and causes the disposable element to fracture at this point when the cover is lifted, as shown in Figure 5. This therefore provides a convenient means, in effect a built-in lever, for authorised personnel to break the disposable element and open the locking device.

As is conventional with such locking devices, each disposable element may have a unique serial number or other identification permanently marked thereon.

As will be apparent from the above description, this device provides two advantages over that of British Patent No. 1 424 680. It is possible to pre-load the disposable elements at a time of day when office staff are less busy than just prior to catching the post.

When the envelopes are to be sealed, the zips can be closed and the disposable elements locked under the covers in a single action. The trunnion mounting of the cover member provides a built-in lever for breaking the disposable elements when the envelopes are to be opened by authorised personnel.

Figures 6, 7 and 8 show an embodiment of the invention which is slightly modified compared Figures 3 to 5, the corresponding parts being indicated by the same reference numbers. In Figures 6 to 8, the trunnion mounting of the cover member is raised above the level of the peg. This has the effect that lifting of the cover tends to move the peg to the side, i.e. towards the hooks, and this causes the disposable element to break by pulling the hooks away from the body of the disposable element.

Figures 9 to 11 show a variation on the means for mounting the disposable element on the slider. The slider has a projecting post 25 in place of the more usual swinging pull. This post has a cylindrical lower part and a flat upper part. In this modification, the disposable element is provided with an elongated slot near its end remote from the hooks, the central part of the slot being widened to a diameter corresponding to the lower part of the post 25. The disposable element can thus be inserted onto the upper part of the post, then rotated by a quarter turn so as to lock it thereon.

This corresponds to the press-fit action of the disposable elements shown in Figures 3 to 8. The disposable element is then locked under the cover member and ruptured by means corresponding to those previously described.

In the embodiment of Figures 12 to 16, parts corresponding to previous embodiments are shown by the same reference numbers. The disposable element 4 is joined to the slider 2 by a projecting post 25 in the same manner as in Figures 9 to 11. However, in this embodiment, the design of the cover member 11 is somewhat different, so as to provide an alternative method of breaking the disposable element 4. The cover member 11 comprises a flat peripheral portion 32 which is joined to the surface of the reusable envelope or the like by fixing means such as rivets through holes 33. A central raised portion of the cover member comprises front and rear parts 34 and 35 of a cylindrical chamber.

Rotatably located within the parts 34 and 35 is a canopy 36 which is rotatable about an axis parallel with the line of the zip, as shown in Figures 14 to 16. The canopy 36 has an integral lateral tab 37 to assist in the lifting action. The canopy 36 is rotatably located at its front and rear by a shaped side part 38 and a central shoulder 39, which can slide around a circular track 40 defined inside each of the front and rear parts 34 and 35.

A front wall 41 of the canopy has defined therein rectangular slot divided into two parts by a central peg llA, which cooperates with the resilient hooks 9 of the disposable element 4, as in previous embodiments.

Immediately forward of the front wall 41 is a'fixed wall 42 which has a corresponding rectangular slot 43 defined therein. On lifting the side tab 37, a shearing action is therefore exerted on the disposable element 4 by relative movement between the walls 41 and 42. As shown in Figures 14 to 16, one side of the disposable element will be forced upwardly and the other side will be forced downwardly, so that the disposable element is broken by a twisting action. To assist this action, one or more of the cooperating edges of the rectangular slots in the walls 41 and 42 can be shaped to form a cutting edge, as shown at 44 in Figure 13. An advantage of this method of rupturing the disposable element is that the limbs of the disposable element are broken in opposing directions, so that the required forces are, to a useful degree, carried within the cover member, enabling its mass to be minimised.

Claims

CLAIMS:

1. A sliding fastener having means for tamperevident locking in the closed position, comprising a slider to effect closing of the sliding fastener, a disposable locking element engagable at one end with the slider and resiliently deformable at an opposite end, and a cover member arranged near the slider in the closed position and defining an opening through which said opposite end of said disposable locking element is slidingly insertable by resilient deformation but not slidingly retractable therefrom, whereby engagement of the disposable locking element with te slider and with the cover member prevents opening of the sliding fastener without rupture of the disposable locking element.

2. A sliding fastener according to Claim 1, wherein the cover member is hingeable upwardly and includes an edge which is adapted to press against the disposable locking element and cause it to rupture during such upward hingeing.

3. A sliding fastener substantially as hereinbefore described with reference to and as shown in Figures 3 to 11 of the accompanying drawings.