Patent Application
20070125140
An Electronic Article Surveillance (EAS) system is designed to prevent unauthorized removal of an item from a controlled area. A typical EAS system may comprise a monitoring system and one or more security tags. The monitoring system may create an interrogation zone at an access point for the controlled area. A security tag may be fastened to an item, such as an article of clothing. If the tagged item enters the interrogation zone, an alarm may be triggered indicating unauthorized removal of the tagged item from the controlled area. In general, the security tag must be deactivated before a tagged item can leave the controlled area without triggering the alarm.
Security tags may take a variety of forms including soft tags and hard tags. In general, soft tags are disposable and used only once, while hard tags are reusable. An example of a soft tag is an adhesive-backed security label. A soft tag may be deactivated by a deactivator unit, such as a scanner that uses a specific field to deactivate the soft tag when it touches or comes in close proximity to the soft tag.
Hard tags typically comprise a plastic tag body housing an EAS sensor and a locking mechanism including a pin or tack which passes through the item and is clamped to the tag body to secure the item and tag together. In general, a hard tag requires a detacher unit to remove the tack from the tag body and allow the item to be separated from the hard tag. In some applications, a detacher unit may include a magnet assembly which applies a magnetic field to the tag body for releasing the tack.
In many tagging applications, such as tagging of bottles and compact discs, for example, the clamping mechanism of a hard tag may be embedded in the existing packaging of an item or may have a low profile to minimize vulnerability of defeats and facilitate shelving of items. For such applications and packaging requirements, a different detacher design is required to provide open access to the embedded or low profile clamping mechanism and, at the same time, providing a sufficient magnetic field.
Numerous specific details may be set forth herein to provide a thorough understanding of the embodiments of the invention. It will be understood by those skilled in the art, however, that the embodiments of the invention may be practiced without these specific details. In other instances, well-known methods, procedures, components and circuits have not been described in detail so as not to obscure the embodiments of the invention. It can be appreciated that the specific structural and functional details disclosed herein may be representative and do not necessarily limit the scope of the invention.
It is worthy to note that any reference in the specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. The appearances of the phrase “in one embodiment” in various places in the specification are not necessarily all referring to the same embodiment.
In various embodiments, the permanent magnets may comprise paramagnetic components such as samarium (Sm) and neodymium (Nd) and ferromagnetic components such as iron (Fe) and cobalt (Co). During the fabrication of permanent magnets, a crystalline domain structure may be created which exhibits oriented intra-domain magnetization known as magneto-crystalline anisotropy, which is the mechanism that produces strong magnetic fields. The permanent magnet may undergo processing including, for example, compression of components in the presence of an ambient magnetic field, sintering of the compressed material, and remagnetization.
Examples of permanent magnets include but are not limited Neodymium Iron Boron (NdFeB) magnets, hard ferrite magnets, and cobalt magnets such as Samarium Cobalt (SmCo) magnets and Aluminum Nickel Cobalt (AlNiCo) magnets. The permanent magnets may comprise sintered and/or bonded magnets. The permanent magnets also may include a variety of coatings to deter corrosion.
In various embodiments, the magnetic detacher 30 is structured and arranged to provide open access to various magnetic clamping mechanisms. As such, the magnetic detacher 30 is capable of disengaging the clamping mechanism of a hard tag placed at any angular position relative to its axis. In various implementations, the magnetic detacher 30 is configured to provide a relatively symmetric field about its axis making it usable for hard tag placed at any angular position.
In the embodiment shown in
In some embodiments, the top surface 34 of the cylindrical magnet 32 may be slightly offset upwardly or downwardly from the top surface 35 of the ring magnet 33. For example, the top surface 34 of the cylindrical magnet 32 may offset by 2 to 3 mm higher or lower from the top surface 35 of the ring magnet 33. The embodiments are not limited in this context.
In various embodiments, the magnet assembly 31 comprises a ring magnet 33 that is magnetized radially. The ring magnet 33 may comprise, for example, multiple sections 36-1-n, where n represents a positive integer value and each of the multiple sections 36-1-n is magnetized in a direction pointing to the center of the ring magnet 33. In the embodiment shown in
In some embodiments, the orientation of magnetization shown in
In various implementations, the magnet assembly 31 provides a relatively symmetric field about its axis making the magnetic detacher 30 usable for a hard tag placed at any angular position. In some embodiments, soft iron material can be placed at the bottom of the magnet assembly 31 to achieve keeper effect and enhance the surface field.
In various embodiments, the ring magnet 33 may be divided into four or more sections with each magnet section magnetized in a direction pointing to the center of the ring magnet 33. It can be appreciated that with less than four sections, the ring magnet 33 may have substantial field variation so that the clamping mechanism can only be disengaged at specific angular positions.
In various embodiments, the magnetic detacher 40 is structured and arranged to provide open access to various magnetic clamping mechanisms from one side of the magnet assembly 41. As such, the magnetic detacher 40 is capable of disengaging the clamping mechanism of a hard tag placed at various angular positions relative to one side of the magnet assembly 41. In general, the height of the half-ring magnet 43 (e.g., 12 mm) will be greater than the height of the ring magnet 22 (e.g., 7 mm) of the conventional magnet assembly 20 to provide a sufficient magnetic field to disengage various clamping mechanism of hard tags while providing open access to one side of the magnet assembly 41. The embodiments are not limited in this context.
In various embodiments, the magnetic detacher 50 is structured and arranged to provide open access to various magnetic clamping mechanisms. In the embodiment shown in
TABLE 1 illustrates a comparison of magnetic surface fields in kilo-Gauss (kG) at the center on a cylindrical magnet for various magnet detacher configurations. The configurations may include a ring magnet having an inner diameter (ID), an outer diameter (OD), and height (h).
As shown in TABLE 1, the detacher configuration using only a single cylindrical magnet provides a much lower surface field than the detacher configurations using a magnet assembly. To achieve open access with a single magnet configuration would require employing only a cylindrical magnet, for example, by removing the ring magnet 22 from the conventional magnet assembly 20. Such approach compromises the detaching field as the clamping mechanism must be designed to be opened by a weaker magnet and thus made more susceptible to defeat by a “street” magnet.
As also shown in TABLE 1, a similar field to that provided by the conventional detacher configuration using a ring magnet on a cylindrical magnet can be achieved with the appropriate choice of dimensions for a ring magnet that can fit over a cylindrical magnet. As such, the detacher configurations using a ring magnet flush with a cylindrical magnet provide open access and a sufficient field with the appropriate choice of magnet dimensions. For example, the height of the ring magnet (e.g., ring magnet 33) can be increased to 12 mm, or alternately, the outer diameter can be increased to about 60 mm to achieve a magnetic field level of about 7.1 kG for such detacher configurations. In addition, the detacher configuration using a half ring magnet having a height of about 12 mm stacked on a cylindrical magnet also may provide a sufficient magnetic field while allowing open access from one side of the magnet assembly. The embodiments are not limited in this context.
The discussion and field values above are based on using grade 35 NdFeB magnets. If a higher grade of magnet such as a grade 50 NdFeB magnet is used, the magnetic field levels typically will increase by 10-15%. The embodiments are not limited in this context.
In various implementations, the described embodiments comprise a magnetic detacher to provide open access to various hard tags and a sufficiently strong magnetic field level for disengaging the clamping mechanism of such hard tags. The described embodiments may be employed in a variety of tagging applications, such as tagging of bottles and compact discs, for example, where the clamping mechanism of a hard tag is embedded in the existing packaging of an item or may have a low profile to minimize vulnerability of defeats and facilitate shelving of items.
In various implementations, the described embodiments avoid the need to use a high profile or protruding design in tagging applications such as tagging bottles and compact discs. The use of a protruding clamp on a slender package such as that of a compact disc, jewel case, or eyeglass wear is often problematic since the protruding clamp is prone to being snapped off or other tampering. The use of a protruding clamp also hinders efficient use of shelf space since the protrusion consumes space and makes stacking or arranging merchandise difficult.
In various implementations, the described embodiments comprise a magnetic detacher using a magnet assembly that provides a higher magnetic field level than a detacher configuration using only a single magnet. Such embodiments avoid the need to design the clamping mechanism of a hard tag to work with a weaker magnet which would lower defeat resistance.
While certain features of the embodiments have been illustrated as described herein, many modifications, substitutions, changes and equivalents will now occur to those skilled in the art. It is therefore to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the embodiments.
