EP1091063A2

EP1091063A2 - Ball lock for use in anti-shoplifting tags

Info

Publication number: EP1091063A2
Application number: EP00203503A
Authority: EP
Inventors: Renatus Jacobus Leonardus Zeelen
Original assignee: Nederlandsche Apparatenfabriek NEDAP NV
Current assignee: Nederlandsche Apparatenfabriek NEDAP NV
Priority date: 1999-10-08
Filing date: 2000-10-09
Publication date: 2001-04-11
Also published as: EP1091063A3; NL1013251C2

Abstract

The invention relates to a ball lock, for instance for use in anti-shoplifting labels, which ball lock is uncoupled from the protective needle (9) by applying a composite magnetic field produced by two or more magnets(10) which, in a specific position and polarization, must be brought near the wafer, so as to exert a force perpendicular to an uncoupling part (3). When a magnetic field is applied at the wafer, produced by one or more magnets (10) which have not been properly placed or polarized, the ball lock will not uncouple the protective needle (9), because the uncoupling part (3) is then drawn askew.

In this ball lock the wafer need not be placed so as to be directed to this composite magnetic field of two or more magnets, because the uncoupling part (3) in the wafer can rotate such that the metal parts or the magnets (10) fastened thereon come to lie precisely opposite the proper magnets (10).

Description

The invention relates to a ball lock, in particular for fastening anti-theft labels to shop articles, comprising a housing with a tapering receiving space for balls, a multiple of balls received in the receiving space, an opening in the receiving space for passing through a pin from outside the ball lock between the balls, of which receiving space the diameter decreases in a releasing direction in the receiving space directed towards the opening, a spring element for exerting on the balls such a force that the pin can be retained between the balls in collaboration with an inner wall of the receiving space, and an uncoupling body provided with a magnetic and/or magnetizable material for exerting, by means of a magnetic uncoupling field, such a force on the spring element that the pin jammed between the balls is released and can be removed from the opening.
In this fastening device, hereinafter referred to as ball lock, a protective needle is inserted in a central opening of a housing in which are contained, in a conically shaped space, one or several balls which are pressed against the conical walls by a spiral spring.
The invention also relates to an assembly comprising an anti-theft label and a ball lock. The invention further relates to a process for releasing a pin from the ball lock.
Such a ball lock is known from Dutch patent 189054 (NL).
In the products to be protected from shoplifting the wafers are fastened to these products. These wafers are electronic detection plates which, when located in the electromagnetic field of the gates which, normally speaking, are placed at entrances and exits of the shop spaces to be protected, can be detected. The wafer is fastened to the article to be protected by means of a protective needle or a protective cord, which is passed through the article to be protected, after which the protective needle or cord is inserted in the ball lock of the wafer. The wafer is now protected from fraudulent removal. When the protected article has been paid for, the wafer is removed by the shop personnel. This removal of the wafer from a protected article takes place by means of a magnetic field from an uncoupling apparatus which draws the balls free from the protective needle. When a customer, intentionally or unintentionally, forgets to have the wafer removed, the wafer is detected at the shop exit by the gates placed there. These gates will then start giving a sound alarm and, optionally, a light signal.
The drawback of the present types of ball locks is that they can be uncoupled by means of a magnetic field caused by a single magnet or some magnets in stacked condition, placed or not placed in a housing functioning as pole shoe. Thus it is possible for a potential shoplifter who possesses one or some sufficiently strong magnets to remove a wafer from a product and to leave the shop space with this product without causing an alarm.
The object of the invention is to remove the above drawbacks. Accordingly, the ball lock according to the invention is characterized in that the ball lock is further provided with a ball cage received in the receiving space so as to be, at least partly, movable in the releasing direction, in which ball cage the balls are received such that they can make contact with the inner wall of the receiving space and the pin, via which ball cage the spring element exerts the above force on the balls, and via which ball cage the uncoupling body can exert the force on the spring element so as to enable removal of the pin from the opening, which uncoupling body is connected with the ball cage so as to be movable with respect to the ball cage over a limited range, and which uncoupling body is provided with a multiple of magnetic and/or magnetizable parts, so that the uncoupling body, at a magnetic uncoupling field corresponding to these parts and composed of different magnetic fields, can move the ball cage with respect to the receiving space in the releasing direction against the force of the spring element to release the pin.
It holds that the balls cannot be drawn free from the protective needle with one, but only with two or more magnets which must be placed in a specific manner with respect to each other. This renders the fraudulent removal of the pin very difficult, for it is difficult, if not impossible, to properly position the required magnets with respect to each other by hand, partly because the magnets also attract each other.
A ball lock provided with a ball cage is known per se from Dutch patent 1003781. Here the ball cage is made of magnetizable material and therefore functions as uncoupling body. This known ball lock, however, can be released by means of a single magnet. The object of the known ball cage primarily is to force the balls to remain mutually arranged in one plane with respect to each other. This has the result that when uncoupling the ball lock, using the single magnetic field, the balls are actively drawn loose out of the conically shaped space through the magnetic field also attracting the ball cage.
The invention will now be described in more detail with reference to some figures, in which
Fig. 1 shows the cross-section of the existing ball lock;
Fig. 2 shows the cross-section of the ball lock according to the invention;
Fig. 3 shows the cross-section of the ball lock according to the invention with a protective needle placed therein;
Fig. 4 corresponds to Fig. 3, but then in the situation in which the ball lock is kept to the composite magnetic field of one or two magnets;
Fig. 5 corresponds to Fig. 3, but then in the situation in which the ball lock is kept to the composite magnetic field of three magnets;
Fig. 6 shows the uncoupling part according to the invention;
Fig. 7 shows the placement of the three magnets with which the ball lock in the wafer can be released from the protective needle;
Fig. 8 corresponds to Fig. 3, but then in the situation in which two differently polarized magnets are placed on the uncoupling part;
Fig. 9 corresponds to Fig. 8, but then in the situation in which the ball lock is kept to the composite magnetic field of two differently polarized magnets.
Figure 1 shows the present ball lock. This ball lock is known and is described in patent 189054 (NL) of applicants. Located in this ball lock are three hardened steel and magnetizable balls 7 in a deep-drawn steel lock bush 4. The balls are pressed down by a steel and magnetizable tubular rivet 5 and a spiral spring 6. A lock housing 11 made of plastic is placed over this whole and is fastened to the lock bush by means of a snap connection. This composition is built into the wafer.
Figure 2 shows the construction of an assembly of a ball lock and a wafer according to the invention. The wafer consists of two plastic dish parts 1 and 2. The ball lock is placed in the heart of the wafer. This ball lock comprises a round brass lock bush 4. The lock bush 4 comprises a tapering receiving space 20. The ball lock is further provided with the opening 22 for a pin 9. The diameter of the receiving space 20 decreases in a releasing direction in the receiving space 20 directed towards the opening 22.
Placed in the lock bush 4 is a ball cage 5. This ball cage is made of a non-magnetizable material, which is not attracted by a magnet. Provided in this ball cage are three hardened steel balls 7. The ball cage and the balls are pressed down in the lock bush by a spiral spring 6. Placed below the upper edge of the ball cage is an uncoupling body 3, on which three magnetizable metal parts 8 to be attracted by some magnets are fastened. This uncoupling body, like the ball cage, is made of a material type which is not attracted by a magnet.
Figure 3 shows the situation when a pm or protective needle 9 is inserted at the bottom in the central opening 22 of the wafer. The balls 7 then roll along the conical inner walls 24 of the lock bush 4 upwards against the pressure of the spiral spring 6. Through the balls being placed in this ball cage, the balls are forced in this example to remain, independently of the position of the ball cage, in a plane perpendicular to the longitudinal direction of the protective needle. The longitudinal direction of the needle located in the ball lock is also referred to as the releasing direction. When an attempt is made to remove the protective needle from the ball lock, the balls 7 become jammed between the conical wall of the lock bush 4 and the protective needle, which results in such a frictional force that the protective needle cannot be removed. This figure shows that the uncoupling body 3 with the three metal parts 8 fastened thereon comes to lie more or less loose. In other words, the uncoupling body is connected with the ball cage so as to be movable with respect to the ball cage over a limited range. The only thing which keeps this body 3 in position is the ball cage 5. Through this coming to lie loose the uncoupling body 3 has the possibility of slightly tilting and rotating around the ball cage.
Figure 4 shows the situation when at the top of the ball lock a magnetic field is applied from one or two (permanent or electro-) magnets 10. Through this magnetic field a rotation and tilting will be effected at the uncoupling part 3 through the attraction of one or two of the metal parts 8. First, the uncoupling part will begin to rotate such that one or two of the metal parts 8 come to lie precisely opposite the magnet 10 or magnets 10. The tilting which results is that the uncoupling part 3 comes to lie askew in the wafer. This effect is clearly shown in Figure 4. Through this lying askew of the uncoupling part the ball cage will not move and, accordingly, not release the balls from the protective needle 9.
Figure 5 shows the situation when at the top of the ball lock a composite magnetic field is applied from three magnets 10, as shown in Figure 7. By placing the three magnets 10 the uncoupling part 3, through the simultaneous attraction of the three magnetizable metal parts 8, will be attracted straight in the direction of the three magnets. Because the uncoupling part can rotate, the position of the three metal parts, when applying the magnetic field, has no influence. The uncoupling part itself will begin to rotate such that the three metal parts come to lie precisely opposite the magnets. With this the ball cage 5 is taken along against the spring force of the spiral spring 6. The ball cage, for its part, draws the balls 7 out of the conical part of the lock bush 3. Because of this the balls come to lie free from the protective needle 9, and the jamming of the protective needle is removed. The protective needle can now be removed from the ball lock and from the wafer.
Besides, the metal parts 8 may also be made of magnet material. One of the three magnets 8 may then be placed on the uncoupling part with a deviating pole, that is to say with a deviating magnetization direction with respect to the other two magnets 8, so as to result in a polarization of, for instance, north-north-south. When a ring magnet 14, which is large enough to be placed around the plastic below which the ball lock is located, is kept to the wafer, the uncoupling part will also be drawn askew in the wafer and the protective needle will not come to lie free from the balls (see Figure 4).
In the case in which three magnets 8 are fastened on the uncoupling part (that is to say the parts 8 are magnetic) in such a manner as to result in a polarization of, for instance, north-north-south (see also Figure 6), the magnetic field applied, with which the protective needle has to be uncoupled, must be adapted thereto. The magnets 10 must then be specifically polarized in south-south-north. At two of the three magnets 10 shown in Figure 7 the magnetization directions must then be reversed. If this is not the case, the uncoupling part will be drawn askew and the balls will not come to lie loose from the protective needle and the protective needle cannot be taken from the wafer.
Figure 6 shows the uncoupling part 3. The uncoupling part is substantially dish-shaped and extends around the ball cage. Here 3 is a plastic part and is not attracted by a magnet. On this plastic part are fastened the three metal parts 8. These, however, must be able to be attracted by a magnet. The magnetic and/or magnetizable parts 8 are positioned near an edge 16 of the dish-shaped uncoupling body.
Figure 7 shows the magnets with which the ball lock in the wafer can be uncoupled from the protective needle. Here the ball lock may be designed as in Figure 5, with the parts 8 being magnetizable. In this connection it should be noted that without a housing in which the three magnets can be placed, efforts to keep the three magnets together in such a manner will not be successful. The manner in which the magnets are placed cause a very strong repelling force on each other. This renders it impossible to use several magnets offhand to illegally remove a wafer.
Figure 8 shows a construction of the ball lock and the wafer in which two parts 8 are fastened on the uncoupling body 3 in the form of magnets 8 which are each provided on the uncoupling body in a differently polarized condition.
Figure 9 shows the situation when at the top of the ball lock of Figure 8 a composite magnetic field is applied from two magnets 10 which are differently polarized. This will cause the uncoupling body 3 to rotate such that the two magnets 8, which are provided on the uncoupling part, come to lie precisely opposite the two magnets 10 of the field applied. The uncoupling part will be attracted in the direction of the two magnets without tilting, during which the ball cage 5 is taken along against the spring force of the spiral spring 6. The ball cage, for its part, draws the balls 7 out of the conical part of the lock bush 4. As a result of this, the balls come to lie free from the protective needle 9 and the jamming of the protective needle is removed. The protective needle can now be removed from the ball lock and from the wafer.
The use of a large (ring) magnet with the purpose of illegally removing the wafer is rendered impossible because of the fact that the uncoupling part is attracted on one side, while the other side is repelled. This will cause the uncoupling part to tilt, with the balls not being drawn out of the conical part.
In particular, the invention therefore relates to a fastening device, in particular for fastening anti-shoplifting labels to shop articles, in which a protective needle can be passed through an opening in a ball lock having therein, in a conical space, one or several balls completely or partly surrounded by a ball cage which forces the balls to remain in a plane perpendicular to the protective needle, while they are pressed by a spiral spring against the wall of the conical space, so that through the balls jamming in the conical part the protective needle cannot be removed. The balls are drawn loose via an uncoupling part only if this uncoupling part, without tilting, moves in the releasing direction of the balls by means of a special tool in the form of an uncoupling apparatus with two or more magnets and not when the uncoupling part tilts, which is the case with illegal attempts to uncouple the ball lock by means of one or several loose magnets by hand, because the forces which these magnets exert on each other render it practically impossible to manually get these magnets into a proper position corresponding to the position of the magnets in an uncoupling apparatus. By applying a predetermined composite magnetic uncoupling field from two or more magnets at the wafer, the uncoupling part rotates independently such that the two or more metal parts provided thereon come to lie precisely opposite the magnets of the composite magnetic field.
By applying the uncoupling field from two or more magnets at the wafer, the uncoupling part is attracted such that this uncoupling part draws the ball cage out of the conical part, so that the balls come to lie loose from this conical part, as a result of which the protective needle comes to lie loose from the balls and can be removed from the ball lock and the wafer.
The application of a magnetic field from one or two magnets which are not properly polarized has the result that the uncoupling part tilts such that the ball cage is not drawn out of the conical part, so that the balls are not drawn out of the conical part and the balls do not come to lie loose from the protective needle, as a result of which the protective needle cannot be removed from the wafer.
Instead of two or more metal parts there can be used two or more magnets which are polarized in such a manner that a magnetic field applied, with the purpose of allowing the protective needle to come loose from the balls, also has to comply with a specific polarization. If this polarization is not satisfactory, then the uncoupling part will be drawn askew and the balls will not come to lie loose from the protective needle, which therefore cannot be removed from the wafer.
The application of a magnetic field from a large magnet, ring magnet or electromagnet has the result that the uncoupling part tilts. Because of this the ball cage is not drawn out of the conical part and the balls do not come to lie loose from the protective needle, which therefore cannot be removed.
The invention is by no means limited to the above embodiments. In the above examples the parts 8 are separated from each other in distance, but this is not necessary. The parts 8 or a number thereof may also connect together and/or form one whole. The magnetization directions of the parts 8 may also coincide or enclose an angle of 180 degrees. Preferably, the parts have at least two at least almost opposite magnetization directions as shown in Figure 9. Here the magnetization directions (which enclose an angle of 27 degrees with respect to each other) comprise components which are oppositely directed (that is to say enclose an angle of 180 degrees). The balls may be made of a magnetizable or a non-magnetizable material.

Claims

A ball lock, in particular for fastening anti-theft labels to shop articles, comprising a housing with a tapering receiving space for balls, a multiple of balls received in the receiving space, an opening in the receiving space for passing through a pin from outside the ball lock between the balls, of which receiving space the diameter decreases in a releasing direction in the receiving space directed towards the opening, a spring element for exerting on the balls such a force that the pin can be retained between the balls in collaboration with an inner wall of the receiving space, and an uncoupling body provided with a magnetic and/or magnetizable material for exerting, by means of a magnetic uncoupling field, such a force on the spring element that the pin jammed between the balls is released and can be removed from the opening, characterized in that the ball lock is further provided with a ball cage received in the receiving space so as to be, at least partly, movable in the releasing direction, in which ball cage the balls are received such that they can make contact with the inner wall of the receiving space and the pin, via which ball cage the spring element exerts the above force on the balls, and via which ball cage the uncoupling body can exert the force on the spring element so as to enable removal of the pin from the opening, which uncoupling body is connected with the ball cage so as to be movable with respect to the ball cage over a limited range, and which uncoupling body is provided with a multiple of magnetic and/or magnetizable parts, so that the uncoupling body, at a magnetic uncoupling field corresponding to these parts and composed of different magnetic fields, can move the ball cage with respect to the receiving space in the releasing direction against the force of the spring element to release the pin.
A ball lock according to claim 1, characterized in that the uncoupling body can rotate around the ball cage and can tilt through a limited angle with respect to the ball cage.
A ball lock according to any one of the preceding claims, characterized in that the uncoupling body extends around the ball cage.
A ball lock according to any one of the preceding claims, characterized in that the uncoupling body is substantially dish-shaped.
A ball lock according to claim 4, characterized in that the magnetic and/or magnetizable parts are positioned near an edge of the dish-shaped uncoupling body.
A ball lock according to any one of the preceding claims, characterized in that the ball cage is at least substantially made of a non-magnetizable material.
A ball lock according to any one of the preceding claims, characterized in that the uncoupling body, with the exception of the above regions, is made of a non-magnetizable material.
A ball lock according to any one of the preceding claims, characterized in that the magnetic and/or magnetizable parts are separated from each other in distance.
A ball lock according to claim 8, characterized in that the parts are magnetic and mutually have at least two magnetization directions different from each other.
A ball lock according to claim 9, characterized in that the magnetization directions of at least two parts comprise components which are oppositely directed.
A ball lock according to any one of the preceding claims, characterized in that balls are arranged by the ball cage at least substantially in one plane which is directed perpendicularly to the releasing direction.
A ball lock according to any one of the preceding claims, characterized in that the balls are made of a magnetizable material.
An assembly provided with an anti-theft label and a ball lock according to any one of the preceding claims.
A process for releasing a pin from a ball lock according to any one of the preceding claims, characterized in that by means of at least two magnets (permanent or electromagnets) at least two different magnetic fields are generated to obtain a magnetic uncoupling field, with the uncoupling part moving with respect to the ball cage such that the parts each direct themselves opposite one of the magnets, after which the uncoupling body moves the ball cage without tilting in the releasing direction against the spring force of the spring element to release the pin.