TECHNICAL FIELD OF THE INVENTION

The present invention relates to a method of producing a marking-substance containing ampul and an ampul intended for use in a theft-deterrent device for theft-attractive goods. The ampul contains a marking or staining substance and is intended to be arranged in a theft-deterrent device in a manner such as to be broken, crushed or destroyed in some other way and therewith release the marking substance enclosed in the ampul when an improper or unauthorized attempt is made to release the device from the theft- attractive article. The invention also relates to a theft- deterrent device which includes such an ampul.

BACKGROUND OF THE INVENTION

Theft deterrents are used with the intention of preventing or deterring theft of theft-attractive goods, such as clothing, bags, handbags, suitcases and other retail articles that can be easily carried. A device of this kind is intended to be attached to an item of goods in such a manner that the device can only be released with the aid of a special release device, to which potential thieves are assumed not to have access. Attempts to remove the theft-deterrent device without the aid of this special release device renders the goods practically unusable, either by virtue of the goods being torn or by virtue of a fragile ampul in the theft-deterrent device containing a marking substance bursting and releasing the substance and therewith mark or stain the goods or damage the goods in some other way.

Theft deterrents may also include means that enables the presence of the theft-deterrent device within a surveillance

zone to be detected. Theft deterrents of this kind are carriers of alarm elements, such as for example transponders or radiofrequent coils and capacitors, that coact with an alarm system which is activated by a sensor arrangement at the exits from the store in which the theft-protected goods are offered for sale. Theft deterrents are often provided with alarm elements as an alternative to marking-substance containing ampuls. However, there are also theft deterrents with coexisting systems, i.e. theft deterrents which include one or more marking-substance containing ampuls and also means, such as transponders or other types of alarm elements, that enable the presence of theft deterrents within a surveillance zone to be detected.

Theft deterrents with coexisting systems are described, e.g. in WO 91/19874, US Patent No 4,649,397, US Patent No 5,347,262 and US 5,438,738.

US Patent No 5,347,262, for example, discloses a theft- deterrent device containing fragile elongated glass vials that fracture when at least a predetermined pressure is applied in order to try to tear the two components of the device apart. A switch assembly and a transponder assembly are arranged in the device such that an attempt to separate the two components apart will result in an alarm signal being radiated by the transponder.

In another document, Swedish Patent Application No 9400429-8, a device for identification and/or marking of equipment, such as computers, printers and the like, is disclosed. The identification/marking device comprises a breakable container containing a marking dye and a microchip-transponder. The transponder is programmed or coded with a personal code for identification of the equipment or the owner of the equipment. The container is fastened to the equipment, e.g. by gluing, such that it will break or crush and release the

dye when an attempt is made to release the container from the equipment.

Microchip-transponders can be used as identification/marking elements for carrying an identification code, such as an identification code of an article or a personal code number, and a transponder can also be used as an alarm element in a theft-deterrent device as described above. However, a major disadvantage of using a microchip-transponder as an alarm element in a theft-deterrent device is that the price of this type of transponder is far too high to make the microchip- transponder-fitted theft-deterrent device price-competitive on the market. Another disadvantage is that a microchip- transponder-fitted theft-deterrent device has a detecting range which is too short to be detected in an ordinary surveillance zone.

An alarm element with a price of about 1% of the price of a microchip-transponder and which consequently is frequently used in theft deterrent appliances, consists of a thin metal strip, wire or filament, preferably made of an amorphous metal alloy having electromagnetic properties, such as for example VITROVAC® (Vacuumschmelze GmbH). The alarm strip is an element which is designed to reflect certain frequencies that can be identified by a receiver in an electromagnetic field. This property is utilized within anti-theft techniques, by placing at suitable positions in the store a transmitter/receiver which can identify or detect a theft- deterrent device or a self-adhesive label securely attached to an item of goods and provided with the alarm strip and therewith trigger an alarm.

The function of an alarm element is impaired or destroyed when the element is physically tampered with, for instance when the element is cut or pierced by a needle or some other sharp object. An alarm element intended for protection of an

item of goods is thus normally fitted in a theft-deterrent device in a manner which prevents direct access to the element and the element is normally placed between two plastic elements which are permanently joined together to form a casing, for instance by ultrasonic welding. However, this type of theft deterrents can be made inoperative by making a hole in the plastic casing surrounding the alarm element with the aid of a knife or by burning a hole with the aid of a cigarette lighter for instance, so that the alarm element can be reached and damaged. The use of a tougher casing material, such as metal, is not practical because a metallic material will normally shut out or disturb the signals in the alarm system.

SUMMARY OF THE INVENTION

The object of the present invention is to reduce or eliminate the possibilities of rendering theft-deterrent devices having this type of price-competitive alarm elements non-functional.

This object is achieved in accordance with the invention with a method of manufacturing an ampul, an ampul and an ampul- fitted theft-deterrent device having the features set forth in the following Claims.

The marking-substance containing ampul of the present invention which is intended for use in a theft-deterrent device for attachment to theft-attractive articles, encloses an alarm strip which can be detected or sensed by an electronic or electromagnetic alarm system and which is inaccessible unless the ampul is broken, crushed or damaged in some other way such as to release the marking substance.

As described above there has been an explicit need for finding a solution to the problem that the alarm function of the theft-deterrent devices is made inoperative. According

to the invention the strip is placed inside the marking- substance containing ampul and accordingly the strip can not be reached to be physically tampered with without the ampul being broken and the marking substance being released. The theft-deterrent device can thus not be made inoperative without rendering the goods unusable.

A microchip-transponder adapted to be contained in a liquid- filled container is an element which is comparatively short, heavy and has a high density. Consequently, such a transponder can be dropped into a liquid-filled container and it will fall to the bottom of the container or it can be dropped into an empty container and it will stay at the bottom when subsequently liquid is being filled into the container.

However, the price-competitive alarm strip has physical properties which lead the skilled man in the art away from a solution to the problem according to the invention. While a microchip-transponder which can be used either for identification/marking, as in Swedish Patent Application No 9400429-8, or as an alarm element, e.g. as in US Patent No 5,347,262, is a comparatively heavy element that easily can be introduced or dropped into a liquid-filled container, the electromagnetic alarm strip is a foil- or thread-thin metal strip, wire or filament which is extremely flexible and light in weight. A strip, wire or filament of this type floats on the surface of a liquid, such as a marking substance, in the ampul due to surface tension. Thus, it is technically and practically impossible to insert the strip into a marking- substance containing ampul or alternatively to insert the strip into an empty ampul and subsequently fill the marking- substance, without the strip floating up on the surface of the liquid. The open end of the ampul is normally closed and sealed in a welding process and the presence of any liquid

and/or any other material, such as the alarm strip, will lead to an insufficient welding process and a leaking ampul.

Another technical problem in the case of subsequent filling of marking substance into a strip-containing ampul is that the light and thin strip which is floating on the surface of the marking substance have a tendency to get stuck on the filling needle and will thus accompany the needle when it is withdrawn from the ampul after filling. On the contrary, a transponder, being both short and heavy, will stay on the bottom of the container and be out of reach of the filling needle.

The method according to the invention, i.e. to insert, press and hold the strip against the inside wall of the ampul during filling of the marking-substance liquid into the ampul and during the ampul closing and sealing process, has made it possible to produce an ampul which is tight and contains both marking substance and an alarm strip.

Additional features of the present invention are further described in relation to the description of the preferred embodiments.

BRIEF DESCRIPTION OF THE DRAWING

The invention will be described below in more detail with reference to exemplifying embodiments thereof and also with reference to the accompanying drawing, in which

Figure 1 illustrates an ampul in accordance with the invention;

Figures 2a-2c illustrates schematically a method according to the invention of producing an ampul as shown in Figure 1;

Figure 3 illustrates by way of example a theft-deterrent device fitted with an ampul as shown in Figure 1;

Figure 4 is a cross-sectional view of the theft-deterrent device taken on the line IV-IV in Figure 3;

Figure 5 is a diagram illustrating schematically the alarm system for detecting the presence of a theft-deterrent device within a surveillance zone.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

Shown in Figure 1 is a tubular, circular-cylindrical ampul 2 made of glass or some other fragile material, for instance a fragile plastic material. The ampul contains a liquid- marking substance 4 in the form of a dye and/or an ill- smelling substance which is intended to stain or otherwise mark an item of goods 6 that comes into contact with said substance, or to destroy said item in some other way. The inner ampul pressure may be higher than atmospheric pressure, or may be at atmospheric pressure or at a pressure beneath atmospheric pressure.

The ampul 2 encloses an alarm strip 8. This alarm strip is preferably freely movable in the liquid substance 4, but may also be attached to the ampul 2 in some suitable way, so as to fixate the position of the strip in the ampul. In this latter regard, the alarm strip 8 may conceivably be attached to the inside of the wall of the ampul 2. An essential feature of all of the aforesaid alternatives is that the alarm strip cannot be reached without breaking the ampul and releasing the marking or staining substance.

The alarm strip 8 has the form of a thin strip, wire or filament of round, flat or some other suitable profile. The

wire or filament is preferably made of an amorphous, softmagnetic metal alloy having electromagnetic properties, although the use of other materials is also possible within the scope of the invention. The strip can be coated with a protective layer of a suitable material, such as for example glass, lacquer or some other coating material The alarm strip can also have the form of a twisted thread and the tread can be coated to prevent untwisting. The alarm strip may also carry and transmit logical information which is appropriate in the present context, such as an alphanumeric code, and which can be read by a sensor arrangement installed in the store. The ampul 2 may also enclose several alarm strips 8, of which one or more may function to reflect the signal sent by the transmitter, while another strip functions as an information carrier.

Figures 2a-2c illustrate schematically a method of producing the ampul shown in Figure 1. In a first step an alarm strip 8 is inserted into an open ampul 2, preferably made of glass or a fragile plastic material, as shown in Figure 2a. Magnets 20, such as for example neodymium magnets, are movably arranged on the outside of the ampul. In a second step, as shown in Figure 2b, the magnets 20 are moved to lie close to the outside wall of the ampul 2 to exert a magnetic force on the strip 8 inside the ampul 2. The strip is forced towards the ampul wall and is held against the wall by the magnetic force. A marking substance filling needle 22 is introduced into the ampul 2 and marking substance 4 is filled through the needle 22 into the ampul up to a level below the open end of the ampul. The magnets 20 hold the strip 8 against the inner wall of the ampul during the filling process, during the withdrawal of the needle 22 from the ampul and also during the subsequent step, the closing and sealing of the ampul 2. While the strip 8 is steadily held against the wall, the open end of the ampul is closed and sealed as shown in Figure 2c, preferably by a welding process 24. In a final

step the magnets 20 are withdrawn from the ampul and the strip 8 is released from the ampul wall.

According to an alternative method of producing an ampul, an adhesive layer is applied either on the alarm strip 8 or on the inside wall of the ampul. The alarm strip 8 is inserted into the open ampul 2 and is subsequently pressed against the wall from the inside of the ampul, e.g. by an airflow directed into the ampul, by the marking-substance needle 22 or by any other internal means. The alarm strip 8 is held against the wall by the adhesive layer between the wall and the strip during the filling and welding processes.

Figures 3 and 4 illustrate by way of example a theft- deterrent device 9 provided with an ampul 2 as shown i Figure 1.

The theft-deterrent device 9 includes a first unit 10 including a connecting unit 11. The connecting unit 11 comprises a base element 12 and an elongated connecting element 14 which projects out from the base element and which is intended to be inserted through the item of goods 6 to be protected. A second unit 16 (shown only schematically in Figure 4 ) is intended to be fitted to the connecting element 14 and locked thereto against movement in a direction away from the base element 12, so as to hold the theft-deterrent device securely to said goods 6. One of the units, in the illustrated case the first unit 10, will include an anti- theft device.

According to the present embodiment of the invention, the anti-theft device is comprised of a fragile ampul 2 which contains a liquid or powdery marking substance 4 and an alarm strip 8 which is disposed in said substance and which can be sensed or detected in an electromagnetic alarm system. The ampul 2 is positioned so as to be clearly visible from

outside the theft-deterrent device. A potential thief is thus able to see the marking substance 4 in the ampul, which naturally has a deterring effect.

Should an attempt be made to loosen the second unit 16 from the connecting element 14 by force, the pulling forces and lateral forces thus exerted on the unit 16 and, consequently also on the connecting element 14 and the base element 12, will cause the ampul 2 to fracture or burst. When the ampul 2 fractures or bursts, the marking substance 4 will spread to the goods 6, thereby destroying the goods and rendering the same unusable. The ampul 2 will also burst or fracture if an improper or unauthorized attempt is made to render the alarm strip 8 inoperative, therewith causing the marking sub- stance 4 to destroy the goods 6.

Figure 5 is a block diagram illustrating schematically the alarm system for detecting the theft-deterrent device 9 within a surveillance zone 30. The alarm strip 8 enclosed in the ampul 2 of a theft-deterrent device 9 in the surveillance zone 30 reflects a signal transmitted from a transmitter 32. The signal is identified by a receiver in a detection system 34 and an alarm 36 is triggered, indicating the presence of the theft-deterrent device 9 in the surveillance zone 30.

It will be understood that the invention is not restricted to the aforedescribed exemplifying embodiment thereof and that several conceivable modifications of the invention are possible within the scope of the following Claims.

For instance, the theft-deterrent device may be constructed to act solely as a carrier of an alarm strip for coaction with an electromagnetic alarm system. In this case, the ampul containing the marking substance and the alarm strip may be arranged in the device in a simpler manner than when the ampul is intended to be broken when an unauthorized attempt

is made to remove the device from the item of goods to which it is attached. The theft-deterrent device may also include several ampuls which may have mutually the same or alternative functions. Thus, each ampul may be arranged in the theft-deterrent device so as to function solely as an alarm strip carrier or solely intended to be broken when an improper attempt is made to remove the theft-deterrent device from said goods, or so that it includes both functions. The ampul may also contain more than one alarm strip having the same or alternative functions.