BACKGROUND OF THE INVENTION

[0001] Security seals are used to indicate that a closed container has remained closed throughout a journey or during transport to show that its contents have not been tampered with. Once fixed, such seals can only be removed by destroying them. They usually include a unique reference number to enable it to be ensured that the seal has not been removed and replaced.

[0002] Such security seals are often colour-coded to facilitate an audit trail. For example, trolleys containing alcoholic drinks loaded onto airlines include a seal of one colour when first delivered to the aircraft to indicate that they are full and have not been tampered with. Such seals are only removed once the aircraft is airborne. Before landing the trolleys now only part full and possibly including part empty bottles are once again sealed to prevent their contents being tampered with, but, this time with a seal of different colour to show that the trolley has been used.

[0003] A popular type of seal is the so-called “padlock seal” which is shaped like a padlock and so is easily recognisable as a lock or seal. Another advantage of this type of seal is that it includes a significant surface area to carry the unique reference number and any logo. Nowadays it is often required that the unique reference number is present in the form of a machine readable barcode. To enable such barcodes to be read easily there must be sufficient contrast between the marking applied to the seal and the background colour of the seal and this is not easy to achieve when the seals themselves are colour-coded.

SUMMARY OF THE INVENTION

[0004] According to this invention a padlock-type security seal includes a recess in its body accessible from the front face which houses a locking collet, the collet, in use, locking the leading end of the hasp of the seal into the body, and a cap welded onto the body to close the recess and seal the collet into the body.

[0005] Preferably, the body of the padlock-type seal is chosen to be a colour which will give a good contrast with the barcode. Thus, preferably the body of the padlock-type seal is formed of white or light coloured material and the barcode elements coloured black or a dark colour. This enables the barcode to be prepared readily by a laser engraving operation and ensures that there is always a good contrast available between the elements of the barcode and the body colour of the seal when reading the barcode. The colour of the cap can vary, again to enable an audit trail of the seals. Where the body of the seal is white or a light colour, typical colours of the cap are white, black, red, orange, purple, yellow, blue or green.

[0006] With the arrangements in accordance with this invention the entire assembly and marking of the seal are all carried out from its front face which facilitates its manufacture.

[0007] Preferably the “hinge” end of the hasp is connected to a tear-off strip which extends perpendicular to and around the lower portion of the body of the padlock-type seal.

[0008] Preferably the tear-off portion terminates in a free tab to enable it to be grasped by the user to remove the seal.

[0009] Since the body and collet of all seals produced are common, the only component that needs to be varied specially to “colour-code” the seal is the cap. Thus with a relatively small inventory it is possible to produce a wide variety of seals.