IMPROVEMENTS IN OR RELATING TO TAMPER EVIDENT CLOSURES

Abstract: A container for use with a tamper evident closure (18) has a neck (10) with first (11) and second (13) opposed thread portions spaced apart and adapted to respectively engage the cap (19) and interconnected ring (20) of the closure when it is initially installed on the container. When the closure is first rotated to remove the cap the ring is caused to rotate therewith and because the thread portions are opposed the cap and ring move in opposite axial directions, that is, in opposite directions along the axis of rotation. This axial movement causes the interconnection to fracture and subsequent tightening of the cap leaves a readily discernible gap between the cap and ring. A stepped ledge (14) between the two thread portions prevents removal of the ring after initial installation.

Description: IMPROVEMENTS IN OR RELATING TO TAMPER EVIDENT CLOSURES This invention relates to containers for tamper evident closures and in particular to the neck portion of a container for a tamper evident closure. The invention also relates to the combination of a neck portion of a container and a cap for use therewith. Tamper evident closures enable a consumer to determine whether the closure has been previously removed and replaced with the possibility that the goods have become contaminated. Closures of the general kind in question here, are wel l known and have been in use for a number of years on mi lk bottles, fruit j uice containers, containers for motor oils and many other types of containers . The closures consist of a cap which seals the container and a tear-off ring which is initial ly connected to the cap by thin j oining members spaced around the circumference of the ring. The j oining members fracture when the cap is rotated due either to the rotational movement of the cap or the axial movement of the cap away from the ring. The ring is retained against rotation by a ratchet arrangement between the neck of the container and the ring or against axia l movement on the neck of the container by a ridge around the neck which engages inwardl y directed l edge members on the ring. In the case of the ratchet arrangement the ring may be removed from the container neck after the c ap ha s been r emov ed but in the other ca s e the ring usua l ly remains on the neck of the container. However, a problem occurs with the known tamper evident closures in the that i t i s of ten not c l ear l y ev ident , wi thout c l ose inspection, that the c losure has been removed and replaced on the container because when it is rep laced the two parts come again into close proximity with each other. Thus there is an increasing number of occasions where a consumer has unknowingly used contaminated goods because of a failure to recognize that the closure had been previously removed. According ly , it is an obj ect of this invention to prov ide a container hav ing an improved neck of the kind adapted for use with tamper evident c losures , whereby i ! " 2 - 1 recognition that the closure has been removed and replaced 2 is made easier. 3 Thus the invention provides a container having a neck 4 of the kind for use with a tamper evident closure, which 5 c losure comprises a cap and an interconnected ring, 6 characterized in that, said neck has first and second thread 7 portions spaced axial ly on said neck for engagement by said 8 cap and ring, respectively, whereby initial rotation of the 9 cap in a direction of removal causes said ring to rotate 10 therewith and move axial ly on said neck in the opposite 11 axial direction to said cap thereby causing fracturing of 12 the interconnection, such that subsequent tightening of the 13 cap leaves a readily discernible gap between said cap and 1 4 said ring. 15 In order that the invention may be more readily 16 understood, one particular embodiment will now be described 17 with reference to the accompanying drawings wherein: 18 Figure 1 is a perspective view of a cap for use with 19 the neck portion of a container according to the invention; ' 20 Figure 2 is a side view of the neck portion of a 21 container according to the invention; _ __ 22 Figure 3 is a cross-sectional view of the cap of Figure 23 1 ; . 24 Figure 4 is an enlarged perspective view of the neck 25 portion of the container shown in Figure 2 with tamper 26 evident closure in place thereon; 27 Figure 5 is a view similar to Figure 4 but showing the 28 closure in the first stage of removal; and 29 Figure 6 is a view similar to Figures 4 and 5 but 30 showing the closure in a second stage of removal. 31 Referring now to the drawings, the neck portion 10 of a 32 container is shown to have a first threaded portion 11 33 adjacent the mouth 12 and a second threaded portion or ramp 34 13 which is arranged on the neck portion 10 away from the 35 mouth 12 by a distance slightly greater than the extent of 36 the first threaded portion 11. The first and second 37 threaded portions are separated by a tapered ledge 14 which 38 has an inclined surface 15 angled at about 60° to the axis 16 of the neck portion 10 and an abutment surface 17 which is normal to the axis 16. As is evident in Figure 2 of the drawings, the first threaded portion 11 is a conventional right-hand, thread and the second threaded portion or ramp 13 is an opposite thread, that is, a left-hand thread. Furthermore, the second threaded portion 13 is a dual flight thread. In other words, the second threaded portion has two starts or two separate ramps. The closure 18 comprises a cap 19 and ring 20 which are initially joined together by a plurality of joining members 21 which are wedge shaped and at their thin end are connected to the outer perimeter of the cap 19. As is evident in the drawings the ring 20 is castellated so as to define openings 22 between the cap and ring when they are joined together and the openings provide inwardly directed ledge members 23 which, after initial installation of the closure, engage the abutment surface 17 to prevent removal of the ring 20 from the neck portion 10. The ledge members 23 are able to distort slightly and cam up the inclined surface 15 so as to pass over the tapered ledge 14 during initial installation of the closure 18 on the neck portion 1 0. Al though it is not cl ear ly evident in Figure 2 , the two separate f l ights of the second threaded portion 1 3 commence at the abutment surface 1 7 of the tapered l edge 1 4. Thus , when the cap 1 9 i s rotated anti-c lockwi se , that i s , in a direction to unscrew the cap from the neck portion 1 0 , the ledge members 23 engage the inclined surfaces of the f lights of the second threaded portion 1 3 which, because they run in a counter direction to the f irst threaded portion 1 1 , cause the ring 20 to move axial ly on the neck portion 1 0 in the opposite direction to the cap 1 9. Also, the dual flights of the threaded portion 1 3 prov ide a coarse pitch thread relative to the first threaded portion 1 1 which causes the axia l movement of the ring 20 to be at a greater rate than the axia l movement of the cap 1 9. As i s ev ident in Figure 5 , this opposed axia l movement causes a rupturing of the j joining members 21 progressively as the ring moves away from the cap such that when the last joining member 21 has ruptured, the ring 20 has moved a discernible distance away from the tapered ledge 14. In other words, rotation of the cap 19 to remove it from the neck portion 10 causes axial movement of the ring 20 in a direction away from the mouth 12 of the neck portion 10. Thus, when the cap is subsequently replaced on the neck portion 10, there is a noticeable spacing between the lower edge of the cap and the upper edge of the ring, that is, ' the adjacent surfaces of the two parts. It is therefore clearly evident that the closure has been removed from the container in question. It should be evident from the description hereinabove that the neck portion described provides an improved arrangement for use with tamper evident closures. Rather than the ring of the closure remaining in the same axial position such that replacement of the cap makes it difficult to discern that the connection between the two parts has been severed, the neck portion according to this invention causes the ring to move in an axial direction away from the cap such that replacement of the cap leaves a very noticeable spacing between the two parts. Whilst the second threaded portion 13 is described as being a dual start thread, this is clearly not essential to the invention since a single start thread may still work effectively. Also, whilst one particular closure has been shown in the drawings, the invention could be clearly adapted for use with other types of closures.

Claims: 1. A container having a neck (10) of the kind for use with a tamper evident closure (18), which closure comprises a cap (19) and an interconnected ring (20), characterized in that, said neck (10) has first (11) and second (13) opposed thread portions spaced axially on said neck for engagement by said cap and ring, respectively, whereby initial rotation of the cap in a direction of removal causes said ring to rotate therewith and move axially on said neck in the opposite axial direction to said cap thereby causing fracturing of the interconnection, such that subsequent tightening of the cap leaves a readily discernible gap between said cap and said ring. 2. A container as defined in claim 1, characterized in that, a circumferential ledge (14) is provided around said neck in an axial position between said first and second thread portions, said ledge is tapered (15) towards said first thread portion and stepped (17) towards said second thread portion and said ring has inwardly directed lugs (23) which engage the step of said ledge to prevent removal of said ring from said neck after initial installation thereon. 3. A container as defined in- claim 2, characterized in that, said second thread portion is a dual flight thread whereby said axial movement of said ring during said rotation occurs at a greater rate than the axial movement of said cap. 4. A container as defined in claim 3, characterized in that, said neck has a greater diameter at said second thread portion than at said first thread portion. 5. A cap arrangement for use in combination with the container of claim 4, characterized in that said ring has a greater diameter than said cap, and said ring and cap are interconnected by means of spaced wedge shaped joining members (21) which have their thin ends connected to said cap whereby the joining members separate from said cap during said axial movement to cause said fracturing of the interconnection. 6. A cap arrangement as defined in claim 5, characterized in that, said ring is of castellated construction defining openings (22) in the ring, which openings are directed towards said cap, and said lugs are formed at said openings, said lugs are adapted to distort slightly and have an inclined surface for engaging the taper of said ledge to cause distortion of the lugs when said cap and ring are first installed on said neck whereby said lugs pass over said ledge and thereafter prevent removal of said ring.

Inventors: DAWSON ROBERT JAMES, DAWSON, ROBERT, JAMES
Applicants: DAWSON ELECTRICS, DAWSON ELECTRICS PTY. LTD.
Application year: 1986
Main classification: B65D23
IPC codes: B65D41