GB2305656A - Child-proof cap - Google Patents

Abstract

A cap for a container has an outer member 22, a screw threaded inner member 8, and a ratchet mechanism 25 which causes the inner member to be screwed onto the container when the outer member is rotated in a first direction, but permits the outer member to rotate independently in a second direction. The cap also has engagement means such as camming surfaces 35 and 36 which can cause the inner member to rotate with the outer member in the second direction so that the closure can be unscrewed without any axial force. The engagement means may be disengaged by rotating the outer member in the first direction. The outer member may have a flexible top wall 21 which can flex between a convex position (fig 8) where the camming surfaces are disengaged and a concave position (fig 9) where the camming surfaces are engaged. The camming surfaces may only be engageable in one or more relative positions of the inner and outer members, such positions being indicated by pips located in detents, and/or visual means such as coloured strips which can be seen through a window in the outer member.

Description

IMPROVED CRILD-RESISTANT CAP This invention relates to a cap for a container, and in particular to a child-resistant screw-top cap which can nevertheless be removed easily by an elderly person or a person with arthritis.

Child-resistant caps are commonly used to close containers used to store various household items which may prove harmful to a child. For instance, medicine such as aspirin or paracetamol and household chemicals such as bleach or cleaning fluids are stored in glass or plastic bottles having child-resistant caps.

Many types of child-resistant caps are available. In one of the most common types, the cap has a lug which locates under a bead on the neck of the container. The cap can be removed only when the lug is aligned with a recess in the bead. This is done by rotating the cap until it is in the correct position relative to the container, by aligning some kind of indicator on the cap and container (usually a visual indicator). Once the lug and recess are aligned, the cap can be removed from the container.

A second type of child-resistant cap comprises an internally threaded inner-cap and an outer cap or outer sleeve. A ratchet mechanism permits the outer cap to rotate independently of the inner cap when the user attempts to unscrew the cap from the container.

Application of an axial force to the outer cap engages a locking mechanism to lock the outer cap and the inner cap, so that anticlockwise rotation of the outer cap results in anticlockwise rotation of the inner cap. The axial force must be maintained at the same time as the rotational force is applied, in order to unscrew the cap from the container.

In both of these two systems a combination of reasoning and force is required to remove the cap from the container. In the first system, the user must align the lug and the recess, and then apply substantial force in order to snap the cap off the container. In the second system, the user must apply a combination of two forces simultaneously (axial pressure and torque) in order to unscrew the cap.

The combination of reasoning and force required not only makes it difficult for a child to remove the cap, but also any person who is unable to exert the required force.

For instance, a sufferer from arthritis may know how to remove the cap, but find it difficult in practice actually to do so.

The fact that the axial force must be maintained in the second system while the torque is being applied also means that the various "grip and turn" tools are of little help in unscrewing the cap.

An ideal child-resistant cap and container system would require no more force than a conventional screw-top cap and would allow "grip and turn" tools to be used.

According to the invention, there is provided a cap for a container, comprising an outer cap member, an inner cap member having a screw thread for engagement with a corresponding screw thread on a container, a ratchet mechanism adapted to cause rotation of the inner cap member with the outer cap member to screw the cap onto the container on rotation of the outer cap member in a first direction, but to permit relative rotation of the outer cap member with respect to the inner cap member on rotation of the cap in a second, opposite direction, and engagement means for locking the inner cap member for rotation with the outer cap member in the said second direction to unscrew the cap from the container, characterised in that the engagement means includes latching means adapted to maintain engagement of the said engagement means such that the cap may be unscrewed from the container without the application of axial force simultaneously with rotational force.

The cap preferably includes means for causing release of the latching means on rotation of the outer cap member in the first direction.

In one embodiment, the outer cap member has a flexible top wall adapted to flex between a convex position and a concave position, and the engagement means is latched by movement of the top wall from the convex to the concave position.

In a preferred embodiment the outer cap member has an annular skirt and a top wall which is attached to the skirt by means of an annular portion having an inner edge and an outer edge, the inner and outer edges of the annular portion being attached by respective flexible hinge portions to the top wall and to the skirt respectively.

The engagement means is latched by movement of the top wall from an upper position to a lower position.

The latching means is preferably such that it can be engaged in only one or more predetermined relative orientations of the outer cap member and the inner cap member.

Means are preferably provided for indicating when the outer cap member and the inner cap member are in the said predetermined relative orientations.

The indicating means may preferably comprise a locating pip and detent on the inner and outer cap members, such that when the outer cap member and the inner cap member are in the predetermined relative orientation, the pip is located in the detent, and wherein a resistance is provided to the seating or the unseating of the pip in the detent. The indicating means may additionally or alternatively include visual indicators on the inner and outer cap members.

In a particularly preferred embodiment, the outer cap member is adapted to bow outwards when the locating pip is located in the detent, thereby providing a tactile and preferably a visual indication that the inner and the outer cap members are in the predetermined relative orientation.

A number of preferred embodiments of the present invention will now be illustrated with reference to the accompanying drawings, in which: Figure 1 is an elevation of an inner cap member of a cap; Figure 2 is a plan view, partially in section, of the inner cap member of Figure 1; Figure 3 is an elevation similar to Figure 1, but with some detail removed for clarity; Figure 4 is a partial section on 'A'-'A' of Figure 2; Figure 5 is an enlarged view of region 'X' of Figure 2; Figure 6 is a schematic view, partially in section, of an outer cap member of a cap, showing only one latch for clarity, with the latch in the normal or (unlatched) position; Figure 7 shows the outer cap member of Figure 6, with the latch in the "latched" position; Figure 8 shows, again partially in section, a cap formed from the inner and outer cap members of Figures 1 and 6 in the "unlatched" position; ; Figure 9 is the same as Figure 8, but in the "latched" position; Figure 10 is an enlarged view of region 'Y' of Figure 6, with some detail removed for clarity; Figure 11 is a plan view of the outer cap member of Figure 6; Figure 12 is a section on 'B'-'B' of Figure 11; Figure 13 shows the same as Figure 12, but with some detail removed, for clarity; Figure 14 is a schematic external elevation of the outer cap member of Figure 13, showing a locating tab; Figure 15 is an elevation of an alternative construction of an inner cap member; and Figure 16 is an alternative outer cap member, suitable for use with the inner cap member of Figure 15.

Figure 17 is an elevation of a further alternative inner cap member of a cap; Figure 18 is a plan view of the inner cap member of Figure 17; Figure 19 is a section on 'A' - 'A' of Figure 18; Figure 20 is an elevation of a further alternative outer cap member, suitable for use with the inner cap member of Figure 17; Figure 21 is a plan view, partially in section, of the outer cap member of Figure 20; Figure 22 is a section on 'B' - 'B' of Figure 21; Figure 23 is an enlarged view of region 'Z' of Figure 22, with some detail removed for clarity; Figure 24 is a plan view, partially in section, of a cap formed from the inner and the outer cap members of Figures 17 and 20, in the "unengaged" position; Figure 25 is a plan view, again, partially in section, of the cap of Figure 24, in the '1engaged" position;; Figure 26 is an external elevation of the cap of Figure 25; Figure 27 is a partial section through the cap of Figure 25, with the flexible top wall in the upper position; Figures 28 and 29 show the cap as in Figure 27, but with the top wall in progressively lower positions; and Figure 30 shows the cap of Figure 25 with the top wall in the lower position.

Referring first to Figures 1 to 5, inner cap member (1) has an internal thread (2) for fitting to a corresponding screw thread on a container. Three cams (3) are equiangularly disposed on the outer surface of inner cap member (1). Each cam (3) has a camming surface (4) and an abutment surface (5).

A step (8) is formed on the upper surface of inner cap member (1), and three equiangularly disposed pairs of ramped projections (9) are formed on the side wall of step (8), the gap between each pair of ramped projections (9) defining a detent (10).

An annular projection (6) is formed on the upper surface of step (8), and three equispaced sockets (7) are formed in projection (6).

A lip (11) forms an undercut (12) at the base of inner cap member (1).

Referring to Figures 17 to 19, an alternative embodiment of inner cap member (1) has annular projections (6) extending directly from its upper surface (that is, there is no step (8) as in Figure 1), and annular projections (6) define 3 sockets (7) of differing sizes (two are equal and short and one is longer). Inner cap member (1) has only a single pair of ramped projections (9) which defines a single detent (10). A channel (13) is formed at the base of inner cap member (1).

Referring to Figures 6 to 14, outer cap member (20) has a flexible top wall (21) and a skirt (22) joined to flexible top wall (21) at a flexible hinge portion (23), such that top wall (21) is resiliently biased into either an upper (convex) position, as shown in Figures 6 and 8, or a lower (concave) position, as shown in Figures 7 and 9.

Three equiangularly disposed resilient tabs (25) project inwardly from skirt (22), and are positioned to engage cams (3) and abutment surfaces (5) on inner cap member (1), so as to form a rachet mechanism such that inner cap member (1) is caused to rotate with outer cap member (20) when the latter is rotated in a clockwise direction to screw the cap onto the container, but free to rotate relative to outer cap member (20) when the latter is turned counter-clockwise.

Three lugs (24) project downwardly from flexible top wall (21), and are positioned so as to engage sockets (7) of inner cap member (1) when the outer cap member (1) is in the lower (concave) position (as shown in Figures 8 and 9).

In this position, lugs (24) and sockets (7) form a latching mechanism which, when engaged, locks inner cap member (1) for rotation with outer cap member (20) when the latter is turned counter-clockwise to unscrew the cap from the container.

Lugs (24) are engageable with sockets (7) only at the three relative orientations of outer cap member (20) and inner cap member (1) in which lugs (24) align with sockets (7).

A tab (27) is moulded on the internal wall of skirt (22) and is positioned so as to engage ramped projections (9) and detents (10) on step (8), to give tactile indication of when outer cap member (20) and inner cap member (1) are in the relative orientations in which the latch can be engaged, by location of tab (27) in detent (10).

In an alternative embodiment, ramped projections (9) may meet without the formation of a detent. In this case a less tactile stimulus is provided.

A retaining bead (26) is formed at the bottom of skirt (22), and engages with undercut (12) to retain outer cap member (20) in place on inner cap member (1) to form cap (30) Triangular bead (28) is formed at the top of skirt (22), below top wall (21). The underside of triangular bead (28) acts as an abutment surface for the upper surface of step (8), thereby preventing inner cap member (1) from rising up inside outer cap member (20) when cap (30) is screwed onto a container.

Referring to Figures 20 to 23, an alternative embodiment of outer cap member (20) has a top wall (21), with two flexible hinge portions (23) forming an annular portion (14). Three lugs (24) project downwards from top wall (21). Two are equal and short and one is longer, as with sockets (7). Thus lugs (24) can engage with sockets (7) in only one predetermined relative position. Top wall (21) is resiliently biased into either an upper position in which it is flat, or a lower position in which it is flat, remaining flat in all positions between these two extremes.

In this alternative embodiment, skirt (22) has a flexible section (15), with tab (27) moulded on the internal surface thereof. Flexible section (15) is adapted to flex outwards from skirt (22) when tab (27) is seated in detent (10) (see Figures 24 to 26).

When cap (30) is formed from inner cap member (1) of Figure 17 and outer cap member (20) of Figure 20, retaining bead (26) sits in channel (13), thereby preventing inner cap member (1) from rising up inside outer cap member (20) when cap (30) is screwed onto a container.

Figure 8 illustrates cap (30) in its normal ("safety") position, with the latch mechanism disengaged. Flexible top wall (21) is in its upper position, and lugs (24) are clear of sockets (7).

Outer cap member (20) is rotated in a clockwise direction to screw internal thread (2) onto the corresponding external thread of a container. Resilient tabs (25) abut abutment surfaces (5) of cams (3) so that inner cap member (1) rotates with outer cap member (20).

Cap (30) can thereby be tightened onto the container.

When outer cap member (20) is rotated in a counter-clockwise direction, resilient tabs (25) pass over camming surfaces (4) of cams (3). Outer cap member (20) therefore rotates independently of inner cap member (1), which does not rotate, and cap (30) is not unscrewed from the container.

In order to unscrew cap (30), outer cap member (20) is rotated in a counter-clockwise direction until locating tab (27) abuts one of ramped projections (9). A further counter-clockwise rotation causes outer cap member (20) to flex slightly, and thereby permit locating tab (27) to become seated in detent (10). This action can easily be carried out by a visually impaired user. In this position, lugs (24) on outer cap member (20) are aligned with sockets (7) on inner cap member (1).

Downward pressure is then applied to flexible top wall (21), in order to move it to its concave (lower) position in which lugs (24) are seated in sockets (7). The latching mechanism is thus engaged, thereby locking outer cap member (20) to inner cap member (1) (as shown in Figure 9).

Cap (30) can be now rotated in a counter-clockwise direction, to rotate inner cap member (1) with outer cap member (20), thereby unscrewing cap (30) from the container.

Flexible top wall (21) remains in its concave (lower) position while cap (30) is being unscrewed. If outer cap member (20) is rotated in a clockwise direction to tighten the cap, however, camming surfaces (35) and (36) on lugs (24) and sockets (7) respectively, cooperate to disengage lugs (24) from sockets (7), push top wall (21) back to the convex (upper) position, and thus reset the cap to its "child-resistant" setting.

The engagement of the latching mechanism of the alternative embodiment of Figures 17 to 30 is illustrated in Figures 24 to 30. Figure 24 shows cap (30) in the unengaged position. If outer cap member (20) is rotated counter-clockwise relative to inner cap member (1), tab (27) abuts one of ramped projections (9). As outer cap member (20) is rotated further, tab (27) moves over ramped projection (9) and is pushed away from inner cap member (1). This causes flexible section (15) to bow outwards from skirt (22). When tab (27) is seated in detent (10), flexible section (15) stays outwardly bowed relative to skirt (22). A tactile indication is thereby provided by flexible section (15) which enables the user easily to locate the engaged position. Figure 25 shows cap (30) in the engaged position.

Once the inner and outer cap members are in the engaged position, the latching mechanism can be operated by applying downward pressure to top wall (21). Movement of annular portion (14) about flexible hinge portions (23) enables top wall (21) to move downwards while remaining flat. This process is illustrated in Figures 27 to 30.

Figure 27 shows cap (30) with top wall (21) in the upper position, and with lugs (24) positioned above sockets (7).

Figure 30 shows cap (30) with top wall (21) in the lower position, and with lugs (24) located in sockets (7).

Figures 28 and 29 show intermediate positions between these two extremes. Top wall (21) remains flat at all times. Once lugs (24) and sockets (7) are engaged, outer cap member (20) can be rotated counter clockwise in order to rotate inner cap member (1) and unscrew cap (30) from the container, as with the previously described embodiment.

In the alternative embodiment shown in Figures 15 and 16, which can be used alone or in combination with the tab/detent arrangement of Figure 5 or Figure 24, a window (43) is provided in skirt (22), and three coloured indicating strips (40) are provided equiangularly disposed on the outer surface of inner cap member (1), such each indicating strip (40) is visible through window (43) only when the outer cap member is in the position at which the latch may be engaged by depressing flexible top wall (21).

In use, outer cap member (20) is rotated in a counterclockwise direction until one of indicating strips (40) is visible through window (43), before depression of the top wall (21).

Indicating strip (40) may consist of one or more coloured portions, for instance green portions, which are visible through window (43) when outer cap member (20) is in an "engageable" position relative to inner member (1), and red portions which are visible when outer member (20) is not in such a position. The number and position of these green portions (or their equivalent) will depend upon the number and position of the predetermined relative positions of outer cap member (20) and inner cap member (1) in which the latch may be engaged by pressing top wall (21). In the embodiment shown in Figures 24 and 25, for instance, there is only one pre-determined relative position. In one embodiment, indicating strip (40) has a number of green portions (or equivalent), but no red portions.

Although in the system described above the detent/tab combinations (10/27) and the lug/socket combinations (7/24) are equiangularly disposed around the cap, in a preferred embodiment, their disposition may be other than equiangular.

Claims (10)

1. A cap for a container, comprising an outer cap member, an inner cap member having a screw thread for engagement with a corresponding screw thread on a container, a ratchet mechanism adapted to cause rotation of the inner cap member with the outer cap member to screw the cap onto the container on rotation of the outer cap member in a first direction, but to permit relative rotation of the outer cap member with respect to the inner cap member on rotation of the cap in a second, opposite direction, and engagement means for locking the inner cap member for rotation with the outer cap member in the said second direction to unscrew the cap from the container, characterised in that the engagement means includes latching means adapted to maintain engagement of the said engagement means such that the cap may be unscrewed from the container without the application of axial force simultaneously with rotational force.

2. A cap as claimed in Claim 1, including means for causing release of the latching means on rotation of the outer cap member in the first direction.

3. A cap as claimed in Claim 1 or Claim 2, wherein the outer cap member has a flexible top wall adapted to flex between a convex position and a concave position, and wherein the engagement means is locked by movement of the top wall from the convex to the concave position.

4. A cap as claimed in any one of the preceding claims, wherein the outer cap member has an annular skirt and a top wall which is attached to the skirt by means of an annular portion having an inner edge and an outer edge, the inner and outer edges of the annular portion being attached by respective flexible hinge portions to the top wall and to the skirt respectively, and wherein the engagement means is latched by movement of the top wall from an upper position to a lower position.

5. A cap as claimed in any one of the preceding Claims, wherein the latching means is engageable only in one or more predetermined relative orientations of the outer cap member and the inner cap member.

6 A cap as claimed in any one of the preceding Claims, additionally comprising indicating means for indicating when the outer cap member and the inner cap member are in the said predetermined relative orientations.

7. A cap as claimed in Claim 6, wherein the indicating means comprises a locating pip and detent on the inner and outer cap members, such that when the outer cap member and the inner cap member are in the predetermined relative orientations, the pip is located in the detent, and wherein a resistance is provided to the seating or the unseating of the pip in the detent.

8. A cap as claimed in Claim 7, wherein the outer cap member is adapted to bow outwards when the locating pip is located in the detent, thereby providing a tactile and a visual indication that the inner and the outer cap members are in the predetermined relative orientation.

9. A cap as claimed in any one of Claims 6 to 8, wherein the indicating means includes visual indicators on the inner and outer cap members.

10. A cap as claimed in any one of Claims 5 to 9, wherein there are three equally-spaced predetermined relative orientations.