The present invention relates to a seal for units to be sealed.

The present invention also relates to a method for the sealing and keeping sealed of such units.

Such a seal is known from US 2007/0120381. The seal comprises a housing and a closing member that i,s

electrically conducting and has a specific impedance value and has a first end that is to be led through a unit to be sealed, which end is movable only in insertion direction within at least a first channel of the housing. The sealing further comprises alternating current organs that measure and guard the impedance of the respective closing member arranged around the unit continuously. The alternating current organs are provided with a first electrical connection that is accommodated in the first channel and in contact with the first end of the closing member and are provided with a second electrical connection that is in contact with the second end. The alternating current organs are arranged to allow an alternating current to flow during a certain amount of time and are arranged to store time- related events in a memory accommodated in the housing regarding the presence of absence of the flow of the alternating current related to the individual impedance concerned.

A disadvantage of the known sealing is the

construction, that is complicated and requires relatively much energy and is costly, since the complex frequency dependant impedance and/or resistance is measured

continuously, possibly at different frequencies, in

dependence of the actual length of the closing member to be cut through and to be destroyed each time it is opened. The present invention has as a goal to provide a solid at least partly reusable, but simple, seal that offers the opportunity of a reduced energy usage, without compromising the safety and reliability.

Therefore the seal according to the invention has the features of claim 1.

An advantage of the seal according to the invention is that the current organs only need to generate direct current and are simpler in construction and have a low cost price. Moreover, the detection of direct current is practically simple and no individual and impedance

dependant closing member needs to be produced. On the basis of the either or not flowing direct current the presence or absence of the closing member can be determined in a reliable manner, with as a result that it is clear whether or not the closing member is present in the housing or is absent or cut through. Therefore attempts of tampering with the seal can be determined adequately and be stored on the basis of local time in an available memory that may

possibly be read at a later moment. By also optionally influencing the length of the time interval during which the direct current flows through the closing member, it becomes possible to keep the local energy consumption limited, as a result of which a battery or accumulator may be used as a current source with limited capacity, price and volume in the seal according to the invention.

In an embodiment, the seal according to the invention is characterized in that the housing comprises a control organ for the release of at least the first channel, which control organ is arranged to enable movement of at least the first end of the closing member in the direction opposite to the insertion direction, possibly only after removal of the lip.

Advantageously, possibly after removal of the lip, movement is possible of at least the first end of the closing member in the first channel in the direction opposite to the insertion direction, as a result of which the seal according to the invention, in particular the housing and the closing member, which can not necessarily be cut through, are fully reusable. The second end may possibly be connected to the housing or may after operation of the control organ be pulled out of the housing entirely, together with the first part.

In a further embodiment of the seal according to the invention wherein the second end is provided with a visible coding that corresponds in particular with a coding

provided on the housing, it is advantageously visible that the respective closing member belongs to the housing of the corresponding seal. This allows for checking whether the closing member or the housing have possibly been replaced by a different closing member or a different housing. Further detailed possible embodiments that are described in the further claims are mentioned together with their corresponding advantages in the following

description .

The seal and the method according to the present invention will now be illustrated on the basis of the attached figures, in which corresponding components are provided with identical reference numerals. Herein:

Figures 1A and IB show a first embodiment

respectively a cut-away view of a seal according to the invention; and

Figures 2A and 2B show a second embodiment

respectively a cut-away view of a seal according to the invention .

The Figures 1A and IB show a first embodiment of a seal for units to be sealed that are not shown, such as devices or instruments that often are to be used once after sealing, or packings or post parcels to be opened or similar units or objects. The sealing 1 comprises a housing 2 and an electrically conducting closing member 3 that is to be led through the unit to be sealed, such that it cannot be used or opened without removal of the closing member or without leading it through or cutting it. The closing member 3 has a first end 4 and a second end 5. At least the first end 4 is movable within a first channel 6 of the housing 2 in the direction of insertion (in the direction of the arrow in Figure 1A) . In the embodiment of Figure 1 the second end 5 is fixed in the second channel 7 between the in this case two members of the housing 2 and the second end 5 provided with a thickening 8 is here provided with a visible coding, for example a barcode or symbolic code. On the housing 2 a similar corresponding coding may be printed as an indication that the closing member 3 and the housing 2 originally belong together and thus have not been replaced.

The seal 1 further comprises within the housing 2 current organs 9, schematically shown, provided with an electrical connection 10 that is electrically in contact with the first end 4 of the closing member 3. In the situation of Figure IB the second end 5 is electrically in contact with the second connection 11. The current organs 9 are arranged to allow an adjustable direct current to flow for a certain interval of time through the closing member 3 that is preferably made of steel . Furthermore the current organs 9 are arranged to store time-related events with respect to the either or not flowing of the direct current frequently in a memory # accommodated in the housing 2 with a programmable microprocessor. Here the starting and stopping of the direct current is detected with the aid of a detection loop 12.

In an embodiment of Figure 1, the first end 4 of the closing member 3 is movable only in the insertion direction through the first channel 6. For this purpose a one way clip has been realized by means of a spring-loaded tipping mechanism 13 that is in the first channel 6 in mechanically clamping contact with the first end 4 that cannot be moved in the direction opposite to the insertion direction due to the wedge action thereof. The spring loading is realized by the first electrical connection 10 that is provided with springs .

In the embodiment of the Figures 2A and 2B, a similar mechanism 13 is also provided in the second channel 7 in the housing 2. Essentially independent thereof this embodiment has a control organ P provided in the housing 2 for the release of movement of the respective end 4, 5 in one or both channels 6, 7. In a specific embodiment the seal 1 comprises a control organ P provided with a

removable lip 14 for release of movement in at least a first channel 6. The control organ P then is arranged to allow operation thereof only after the removal of the lip 14 , in order to allow movement of the first end 4 and/or the second end 5 of the closing member 3 against the insertion direction. The lip 14 that in practice may be realized as a tear-off strip has the function of a kind of seal for the control organ P, such that it becomes possible to establish at a later moment in time that operation or tampering at an earlier moment has occurred. Possibly the breaking or violation of the lip 14 may also lead to the at least partial removal of said coding on the housing such that the possible tampering appears even clearer.

When the seals 1 illustrated above comprise an inner housing 15 that isolates the first connection 10 and the second electrical connection 11, even the strict

requirements regarding tensile strength according to

ISO/DIS 17712.2 may be met, when combined with a steel closing member cable 3 for example made of mutually interwoven fibers. In spite thereof, the current security described remains intact, which can be ascribed to the fact that the inner housing 15 with respect to isolation is constructed as a frame in such a manner that an

electrically conducting contact within the housing 2 between the both ends 4 and 5 is impossible. In other words, the current always flows through the closing member 3 when both ends 4, 5 are inserted in the channels 6 and 7.

When the current organs 9 comprise a Norton type current source, a direct current with a preset desired value is maintained, regardless the direct current

resistance of the mounted closing member 3. This current may be periodical, pulsed or possibly pulse-width modulated and thus needs no continuous energy consumption.