1. Statement of the Technical Field
The inventive arrangements relate to security tags attachable to articles of merchandise, and more particularly a security tag having an improved locking mechanism providing greater defeat resistance.
2. Description of the Related Art
Electronic article surveillance (EAS) systems are well known in the art and are used for inventory control and to prevent theft and similar unauthorized removal of articles from a controlled area. Typically, in such systems a system transmitter and a system receiver are used to establish a surveillance zone, which must be traversed by any article being removed from the controlled area.
An EAS tag is security tag affixed to each article and includes a marker or sensor adapted to interact with a signal being transmitted by the system transmitter into the surveillance zone. This interaction causes a further signal to be established in the surveillance zone, which further signal is received by the system receiver. Accordingly, upon movement of a tagged article through the surveillance zone, a signal will be received by the system receiver, identifying the unauthorized presence of the tagged article in the zone. The security tags are designed to be releasable only by a specially designed implement.
Security tags used in EAS systems often include a locking mechanism which serves to affix the tag to an article. The tag may be locked to the article itself, or the tag can be configured as mated components, which are attachable to one another with a portion of the article secured between the tag components. A common locking arrangement used in security tags is a magnetically-actuatable locking mechanism. These types of security tags use a magnet to unlock the locking mechanism. The magnet interacts with the magnetic components in the lock and actuates such magnetic components to unlock the mechanism.
The invention concerns a tamper-resistant security tag which includes a housing and a movable locking element disposed within the housing. A latch is disposed within the housing and is resiliently biased toward the movable locking element. The latch is movable responsive to application of a magnetic field between a locked position, in which movement of the locking element is prevented by the latch, and an unlocked position, in which movement of the locking element is unrestricted by the latch. A guide structure is provided within the housing and is arranged to constrain a movement of the latch. The latch and the guide structure are cooperatively arranged to facilitate engagement between at least one portion of the guide structure and a portion of the latch. These portions of the latch and the guide structure are strategically arranged to ensure that the engagement will disrupt a motion trajectory of the latch occurring when the housing is subjected to a physical impact. Consequently, the latch is selectively inhibited from moving fully from the locked position to the unlocked position when the housing is subjected to the physical impact.
The invention also concerns a method for preventing defeat of a security tag in a security tag as described herein. The method involves disrupting with the guide structure a motion trajectory of the latch occurring when the housing is subjected to a physical impact so that the latch is selectively inhibited from moving fully from the locked position to the unlocked position only when the housing is subjected to the physical impact. The kinetic energy of the latch associated with such motion trajectory is effectively wasted within the housing by the motion disrupting action of the guide structure.
Embodiments will be described with reference to the following drawing figures, in which like numerals represent like items throughout the figures, and in which:
The invention is described with reference to the attached figures. The figures are not drawn to scale and they are provided merely to illustrate the instant invention. Several aspects of the invention are described below with reference to example applications for illustration. It should be understood that numerous specific details, relationships, and methods are set forth to provide a full understanding of the invention. One having ordinary skill in the relevant art, however, will readily recognize that the invention can be practiced without one or more of the specific details or with other methods. In other instances, well-known structures or operation are not shown in detail to avoid obscuring the invention. The invention is not limited by the illustrated ordering of acts or events, as some acts may occur in different orders and/or concurrently with other acts or events. Furthermore, not all illustrated acts or events are required to implement a methodology in accordance with the invention.
EAS type security tags commonly include a magnetically-actuatable locking mechanism. In such locking mechanisms, the magnetic component of the lock requires a certain mass to generate a sufficient magneto-mechanical response for unlocking the tag. However, it has been found that the mechanical response generated by the unlocking magnet can be duplicated by application of external mechanical force. Application of a sufficient external force (as may be done in an attempt to defeat the tag) could result in the unlocking of the tag. A tag which can be defeated in this manner is obviously undesirable in EAS applications. It is challenging to produce a defeat resistant magnetic lock without compromising the magnetic detach or adding too much cost to the design due to added complexity. Prior solutions include the use of a stronger spring to hold the magnetic component in place. However, the use of stronger springs can cause detaching failure under conditions of authorized tag detachment, or can otherwise require a stronger and more expensive detacher device magnet.
A drawback of the locking arrangement of
The inventive arrangements disclosed herein utilize special features associated with the latch and the plastic housing to provide a low cost solution that drastically reduces the possibility for unauthorized unlocking of an EAS tag by means of mechanical impact forces. The special features provide the ability to restrict the translation of the latch as it moves away from engagement with a locking pin by incorporating an obstructive feature into the housing at strategic location. Translation movement of the latch (as opposed to rotational movement) is the primary response due to a mechanical impact forces such as may occur by swinging and hitting the security tag on a hard surface. A motion trajectory of the latch can be predicted from the orientation the tag is likely hit. One or more special structures are provided in the housing and on the latch to disrupt the rapid translational movements of the latch that may result from such mechanical impact forces, thereby preventing unauthorized unlocking of the tag. In a slower moving detaching process (as would occur in the case of authorized detaching by means of a magnetic detacher) the latch will interact with the special structures on the housing initially but it will eventually be caused to move in a way that facilitates successful detaching. In some instances, the additional required movement may be further translational movement and in other scenarios the additional required movement can be a rotational movement of the latch.
Referring now to
The housing 206 defines a latch channel 230 in which a latch 203 is movably disposed. The latch is formed of a material, such as steel, which is responsive to a magnetic field. Within the latch channel 230, the latch 203 is resiliently biased toward a movable locking element. In this example, the locking element is an elongated pin such as locking pin 202. As can be observed in
In
The latch 203 is movable within the latch channel responsive to application of a magnetic field (not shown). More particularly, when a magnetic detacher (not shown) is placed adjacent to a base portion 218 of the housing, the latch 203 is caused to move in a direction 234, away from the locking pin 202. When the latch 203 has moved a certain distance away from this locked position, the tooth 232 fully disengages from the catch 207 and the locking mechanism is considered unlocked. As such, the latch is movable between a locked position shown in
A guide structure 235 is provided within or as part of the security tag housing 206 and is arranged to constrain a movement of the latch 203. The guide structure includes one or more lateral restraints 236, 238. These lateral restraints are arranged to facilitate translational movement of the latch within the latch channel 230 along a path from the locked position to the unlocked position by constraining movement of the latch in a lateral direction transverse to such path. In an exemplary arrangement shown in
The guide structure 235 is generally arranged to prevent substantial lateral movement of the latch in direction 220. By restricting movement of the latch in this way, the locking pin 202 is similarly prevented from moving in direction 220 within the channel 214 whenever the latch is engaged with the locking pin. From the foregoing, it will be appreciated that the guide structure (and more particularly the lateral restraints 236, 238) described herein generally restrict movement of the latch in direction 220. Nevertheless, the lateral restraints 236, 238 permit latch movement in directions (e.g. direction 234) aligned with the length of the latch channel 230.
An unauthorized person desirous of defeating a security tag will sometimes repeatedly strike the security tag on a hard surface to generate a mechanical response of the latch that is similar to the response generated by an unlocking magnet. When the security tag is abused in this way, the physical mass of latch will cause the latch to have a motion trajectory within the security tag housing that mimics the motion obtained by application of an unlocking magnet. Under certain conditions, repeated striking of the security tag in this way can cause the tag to become unlocked as the latch travels along a motion trajectory in direction 234, away from the locking pin. A tag which can be defeated in this manner is obviously undesirable in EAS applications. In order to prevent defeat of the locking mechanism in this way, the latch 203 and the guide structure 235 are cooperatively arranged to facilitate engagement between at least one first disrupter portion of the guide structure and a second disrupter portion of the latch. These disrupter portions of the latch and the guide structure are strategically arranged to ensure that the engagement will disrupt a motion trajectory of the latch occurring when the housing is subjected to a physical impact. Consequently, the latch is selectively inhibited from moving fully from the locked position in
The exact structure of the first and second disrupter portions is not critical provided that the structures are effective for accomplishing the motion disrupting action described herein. Referring once again to
In accordance with one embodiment of the invention, the first disrupter portion 246 comprises a bump or other protrusion extending into the latch channel 230 from the side wall of the channel housing or guide structure 235. For example, the first disrupter portion 246 can extend in a lateral direction from a side wall (i.e. lateral restraint 238) of the channel housing as shown. The first disrupter portion 246 is designed to interfere with or disrupt the downward translation of the latch as it moves in direction 234 in response to an impact of the security tag on a hard surface. In some embodiments, the first disrupter portion 246 can be provided as part of a lateral wall forming the channel 230 as shown. In this regard, the first disrupter portion can be formed as a part of the housing 206 (e.g. of the same material as the housing), or otherwise can be a separate component attachable to the housing, which may be of a different material than the housing, such as a metal rivet.
It can be observed in
The disrupter portion 246 partially obstructs the downward translation of the latch 203 as would occur if abrupt external forces are applied to the tag, as when the tag is slammed against a hard surface in a defeat attempt. However, the second disrupter portion 248 is comprised of a contoured side of the latch 203 adjacent the first disrupter portion 246. The contour of the second disrupter portion 248 allows the latch to move downwardly past the protrusion formed by the first disrupter portion 246 under certain conditions. In particular, such movement is facilitated when the latch is introduced to a magnetic force of sufficient strength. In the illustrated embodiment, the latch 203 the second disrupter portion 248 is essentially formed as a contoured notch which is configured to have a shape which is partially complementary to the shape of the bump forming the first disrupter portion 246.
The notch formed by second disrupter portion 248 engages with the protrusion of first disrupter portion 246 when the latch is moved in direction 234. This engagement allows the downward translation of the latch 203 only if a steady, uninterrupted force is applied to the latch. Sudden external blows to the tag will not be sufficient to permit the bump to engage with and slide past the notch. In practice, a steady uninterrupted force can only be applied to the latch by the use of the detacher magnet in the detacher device. Accordingly, to unlock the locking mechanism 201, a detaching device is used (not shown) which is constructed and arranged to position a detacher magnet under the latch 203. The latch 203 is pulled downward in direction 234 by the magnetic force until it overcomes the bias of the spring 204 and allows the latch to transition through the engagement of the first and second disrupter portions as described. When the latch 203 finally translates to its fully unlocked position shown in
Shown in
The housing 406 defines a latch channel 430 in which a latch 403 is movably disposed. The latch is formed of a material, such as steel, which is responsive to a magnetic field. Within the latch channel 430, the latch 403 is resiliently biased toward a movable locking element. In this example, the locking element is an elongated pin such as locking pin 402. As can be observed in
The latch 403 is movable between a locked position and an unlocked position. In
The latch 403 is movable within the latch channel responsive to application of a magnetic field (not shown). More particularly, when a magnetic detacher (not shown) is placed adjacent to a base portion 418 of the housing, the latch 403 is able to translate some distance in a direction 408. As shown in
A guide structure 435 is provided within or as part of the security tag housing 406 and is arranged to constrain a movement of the latch 403. The guide structure includes one or more lateral restraints 436, 438. These lateral restraints are arranged to facilitate translational movement of the latch within the latch channel 430 along a path from the locked position to the unlocked position. This is accomplished by generally constraining movement of the latch in a lateral direction transverse to such path. However, the lateral restraints provide a sufficient clearance space 460 to allow for the rotational movement of the latch as described herein. The clearance space can be facilitated by a beveled or chamfered edge 462 which is defined on a portion of the latch adjacent to the lateral restraint 436. The chamfered edge 462 is formed on a portion of the latch diagonally opposed from end portion 444a. The chamfered edge 462 provides an additional clearance space between the latch and the lateral restraint 436 to permit the rotational movement of the latch in direction 434. Maximum rotation of the latch is reached when the chamfered edge engages the lateral restraint 436, or when the end portion 444b contacts the stop 440.
In an exemplary arrangement shown in
The guide structure 435 is generally arranged to prevent substantial lateral movement of the latch in direction 420. By restricting movement of the latch in this way, the locking pin 402 is similarly prevented from moving in direction 420 within the channel 414 whenever the latch is engaged with the locking pin. From the foregoing, it will be appreciated that the guide structure (and more particularly the lateral restraint 438) described herein generally restricts movement of the latch in direction 420. Nevertheless, the lateral restraints 436, 438 provide a sufficient clearance space 460 to facilitate translational latch movement in directions aligned with the length of the latch channel 430 (direction 408) and rotational latch movement in direction 434.
As noted above, repeated striking of a conventional security tag in a certain way can cause the tag to become unlocked. In security tag 400, the latch 403 and the guide structure 435 are cooperatively arranged to prevent defeat of the locking mechanism in this way. When the base 418 of security tag 400 is impacted upon a hard surface, the impact and the physical mass associated with latch 403 will launch the latch along a motion trajectory. This motion trajectory will generally include motion components directed along the length of the latch channel (i.e. in direction 408). In a conventional magnetic lock, this motion trajectory might result in the latch moving from a locked position to an unlocked position. However, in the security tag 400, the end portion 444a of elongated latch leg 442a and stop 440 are cooperatively arranged to disrupt a motion trajectory of the latch occurring when the housing 406 is subjected to such physical impact. More particularly, after an impact, the latch may begin a motion trajectory in a direction 408. But the stop 440 is positioned so that the motion of the latch is disrupted before the tooth 432 can disengage from the catch 407. The stop 440 will produce a counter-acting force to re-direct the motion trajectory of the latch. The re-directed motion trajectory will include motion components directed away from the stop and toward the locking pin 402. These motion components will cause the latch to essentially bounce back toward the locking pin.
Due to the longer length of leg 442a, the impact with the stop can introduce some torque upon the latch in rotational direction 434. However, in contrast to when there is a continuous force upon the latch exerted by an applied magnetic field, the momentary torque produced by the impact of end portion 444a and stop 440 is not generally sufficient to allow the locking pin to be released. Instead, it has been observed that the response of the latch after disruptive interaction of the end portion 444a and stop 440 involves further disruptive interaction as between the catch 407 and the tooth 432. The disruptive interactions prevent the latch from fully rotating out of engagement with the locking pin. It has been observed that in some instances there will be a momentary disengagement of the tooth with the catch, followed by immediate re-engagement as the latch rotates back into its locked position. However, the overall resistance to unlocking is greatly improved as compared to a conventional locking arrangement. Accordingly, the latch is selectively inhibited from moving fully from the locked position to the unlocked position when the housing is subjected to the physical impact.
In the exemplary embodiment in
The inventive arrangements have thus far been described in terms of a security tag device. However, it should be appreciated that the invention also concerns a method for preventing defeat of a security tag as described herein. As such the method involves selectively disrupting with one or more portions of a guide structure 235, 435 a motion trajectory of the latch occurring when the housing 206, 406 is subjected to a physical impact. More particularly, the method involves selectively preventing the latch 203, 403 from moving fully from the locked position to the unlocked position only when the housing is subjected to the physical impact. In the embodiments disclosed in
All of the apparatus, methods and algorithms disclosed and claimed herein can be made and executed without undue experimentation in light of the present disclosure. While the invention has been described in terms of preferred embodiments, it will be apparent to those of skill in the art that variations may be applied to the apparatus, methods and sequence of steps of the method without departing from the concept, spirit and scope of the invention. More specifically, it will be apparent that certain components may be added to, combined with, or substituted for the components described herein while the same or similar results would be achieved. All such similar substitutes and modifications apparent to those skilled in the art are deemed to be within the spirit, scope and concept of the invention as defined.
This application is a non-provisional application claiming the benefit of U.S. Provisional Application No. 61/722,640 filed on Nov. 5, 2012, the entirely which is incorporated herein by reference.
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Number | Date | Country | |
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20140123714 A1 | May 2014 | US |
Number | Date | Country | |
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61722640 | Nov 2012 | US |