Patent Publication Number: US-5025246-A

Title: EAS tag with motion detection facility

Description:
FIELD OF THE INVENTION 
     This invention relates generally to electronic article surveillance (EAS) systems and practices and pertains more particularly to improved EAS tags of the so-called &#34;active&#34; type, i.e., involving self-powering, such as by a contained battery. 
     BACKGROUND OF THE INVENTION 
     Whereas EAS tags are typically of a &#34;passive&#34; type, i.e., do not carry therewith a source of power but rather, respond to incident energy to reradiate the same or a permutation thereof, there are known EAS tags which are of &#34;active&#34; type, carrying therewith a battery or like source of electrical power. Advantage attends the on-board, self-powering capacity, since the tag can thereby be of the so-called &#34;smart&#34; or &#34;intelligent&#34; variety, such as is disclosed in commonly-assigned U.S. Pat. No. 4,686,513, which is incorporated herein by this reference thereto. 
     The tag of the &#39;513 patent, by reason of its on-board power supply, has capacity for processing coded, received messages to assume responsive diverse states and to exhibit different operational characteristics corresponding with such states, thereby expanding the operational states of the tag as contrasted with the passive-type tags. 
     One concern attending active tags is that of power source conservation and measures are known to address this concern. A version of commercial tag of the common assignee, Sensormatic Electronics Corporation, thus included, as a part of the printed circuit board (PCB), which incorporates circuitry related to received message decoding and tag state assignment, electrically conductive traces adapted to be interconnected by movement of an electrically conductive member upon tag orientation change. Thus, one of the states of the &#39;513 patent tag is &#34;Sleep&#34;, wherein its circuitry is dormant, conserving battery life. On movement of the article to which the tag is attached, the intention of the commercial tag under discussion was to &#34;re-awaken&#34; on interconnection of the electrical traces by movement of the electrically conductive member. To the extent that movement of the tag did not insure certainty of such trace interconnections, this prior art arrangement was not as effective as desired in preserving power source integrity while at the same time re-awakening tags, i.e., rendering the tag electrical circuitry active. 
     SUMMARY OF THE INVENTION 
     The present invention has as its primary object the provision of improved EAS tags of the active type. 
     It is a more particular object of the invention to provide for enhanced battery life conservation protection in EAS tags of the active type and enhanced re-awakening capability. 
     In attaining the foregoing and other objects, the present invention provides in combination: 
     (a) an EAS tag inclusive of an electrical power source contained with the tag and circuitry powered by the electrical power source; and 
     (b) a motion sensor operatively associated with the tag and contained therewith, the motion sensor providing output indication of movement and thereupon effecting loading of the the electrical power source by such tag circuitry. 
     The motion sensor comprises first and second housings of electrically conductive material, first and second electrically conductive elements movably supported respectively in the first and second housings, and a joinder member for mechanical interconnection of the first and second housings, the joinder member being comprised of electrically insulative material to electrically isolate the housings from one another and defining a passage permitting movement of the first and second electrically conductive means between the first and second housings responsively to orientation of the tag. 
     The joinder member, the housings and the first and second electrically conductive elements are collectively dimensioned to provide for electrical conductivity between the first and second housings upon reorientation of the tag from a disposition wherein neither of the first and second electrically conductive elements is in registry with the joinder member to other disposition. 
     The foregoing and other objects and features of the invention will be further understood from the following detailed description of preferred embodiments thereof and from the drawings wherein like reference numerals identify like components and parts throughout. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic view of an EAS tag configured in accordance with the invention. 
     FIG. 2 is a side elevational view of a motion sensor constructed in accordance with the invention. 
     FIG. 3 is an end elevational view of the motion sensor of FIG. 1. 
     FIG. 4 is a sectional view as would be seen from plane IV--IV of FIG. 3, with the electrically conductive elements shown without sectioning and in mutually spaced relation. 
     FIG. 5 is a sectional view as would be seen from plane IV--IV of FIG. 3, with the electrically conductive elements shown without sectioning and in contiguous relation. 
     FIGS. 6 and 7 are schematic illustrations which further explain the subject invention. 
     FIG. 8 is block diagram of a system usable with the subject motion sensor for detecting motion as sensed by the motion sensor. 
     FIG. 9 is a timing diagram explanatory of the FIG. 8 system. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS AND PRACTICES 
     Referring to FIG. 1, EAS tag 10 includes mating housing members 12 and 14 having a jointly arranged locking mechanism 16 and pivotable about hinge 18. A receiver-reradiator member 20 and associated active electronics, per the &#39;513 patent, are supported in housing member 14. A battery 22 is supported in housing member 12 and motion sensor 24 is connected with a terminal of battery 22 by conductor 26, conductor 28 extending from motion sensor 24 to circuitry 20. Lines 30a and 30b extend from battery 22 to circuitry 20. 
     In the course of movement or reorientation of the tag, motion sensor 24 provides electrical continuity therethrough and thereupon applies a voltage step, e.g., low (ground potential) to high (battery 22 terminal voltage) or vice versa, to circuitry 20 which incorporates, in addition to the active tag circuitry of the &#39;513 patent, the detection system of FIG. 8, discussed hereinafter. 
     Referring now to FIGS. 2-4, motion sensor 24 will be seen to include first and second housings 32 and 34, each comprised of electrically conductive material and being preferably in the form of a hollow, cup-shaped device. First and second electrically conductive elements 36 and 38, which are desirably metal spheres, are disposed respectively in the first and second housings to be highly mobile therein. A joinder member 40 interconnects the first and second housings and is comprised of electrically insulative material, defining a central passage permitting movement of spheres 36 and 38 between the first and second housings responsively to orientation of the tag. 
     The joinder member, the housings and the first and second electrically conductive elements are collectively dimensioned, as discussed in detail below, to provide for electrical conductivity between the first and second housings upon reorientation of the tag from disposition wherein neither of spheres 36 and 38 are in registry with the joinder member. The latter disposition is seen in FIG. 4, which also shows member 40 to have an interior, circularly continuous rib 40a against which flanges 32a and 34a of housings 32 and 34 abut on assembly, the rib electrically insulating the housings from one another. As is also seen in FIGS. 3 and 4, joinder member 40 includes circularly extending, mutually spaced locking tabs, shown at 40b, 40c, 40d and 40e, which secure the assembly. 
     Turning to FIG. 5, motion sensor is shown in a second disposition, wherein spheres 36 and 38 are in contiguous relation, sphere 38 having rolled into engagement with sphere 36, based on movement of the motion sensor. Sphere 38 is thus in registry with rib 40a, and the sphere diameters and the dimension of rib 40a longitudinally of the movement passage are selected to insure that sphere 38 retains electrical engagement with housing 34 when in engagement with sphere 36 and conversely for movement of sphere 36 into engagement with sphere 38. This event gives rise to electrical continuity between conductor 28, connected to housing 34 and conductor 26 connected to housing 32. The conductive path is thus from conductor 26, through housing 32, through spheres 36 and 38, through housing 34 and to conductor 28. 
     As for the above noted collective dimensioning of the components of the motion sensor, reference is now made to the schematic showings of FIGS. 6 and 7. The motion sensor is elongate, with central, longitudinal axis C. 
     In the FIG. 6 showing, the electrically conductive elements are indicated as blocks 36a and 38a and various dimensions are indicated. Equal lengths L1 and L2 apply to the housings 32 and 34. Lengths L3 and L4 apply to blocks 36a and 38a and are shown as essentially equal to lengths L1 and L2. Length L5 is the dimension of rib 40a along axis C. Given the equality among L1, L3 and L2, L4, the collective dimensioning of components in the FIG. 6 showing, for operativeness of the motion sensor, is simply that each of L3 and L4 exceed L5. This assures that, on motion to which the motion detection is sensitive, one or the other of blocks 36a and 38a will span rib 40a and yet retain electrical connection with its housing when engaging the other block. 
     In the FIG. 7 showing, lengths L3&#39; and L4&#39; of blocks 36b and 38b are shown as equal and less than lengths L1 and L2 as is the case with the spherical elements of the preferred embodiment discussed above. Here, for operativeness of the motion sensor, the sum of lengths L3&#39; and L4&#39; need exceed the sum of lengths L1 and L5 and also need exceed the sum of lengths L2 and L5. 
     Turning to FIGS. 8 and 9, system 50 is used to detect the movement of the electrically conductive elements sensed by the motion sensor. Housing 32 of the motion sensor is electrically connected by line 26 to the negative terminal of battery B, which terminal is the ground reference in the system. Housing 34 is electrically connected by line 28 to input line 52 of system 50. When the elements 36 and 38 are making contact with one another, input line 52 is electrically connected to the negative terminal of the battery. When the elements are separated, the line 52 voltage level is pulled up to the battery voltage V+ through resistor 54, the resistance value of which is very large so that the current through the resistor is minimized when line 52 is grounded. 
     When the motion sensor is at rest, elements 36 and 38 will be stationary and will either be in contact or be separated from one another. Therefore, input line 52 will be at a constant voltage level (ground or V+). When there is movement, the elements will be in random motion, sometimes making contact and sometimes separated. This will cause line 52 to toggle between V+ and ground. The system includes for motion detection a transition detector 56, a latch 58, a timer 60 and an analog switch 62. The system is furnished with clock pulses over line 64 from a suitable clock pulse generator or crystal (not shown). 
     Transition detector 56 is operative to sense a change in voltage level on input line 52, either from ground to V+ or from V+ to ground. When there is no motion, the inputs to exclusive OR (XOR) gate 66 will be at opposite logic levels. If the upper input is high (logic 1), the lower input will be low (logic 0) and vice versa, since the lower input is connected to the upper input by an inverter 68. The following truth table applies. 
     
         ______________________________________                                    
         UPPER        LOWER                                               
STATE    INPUT        INPUT    OUTPUT                                     
______________________________________                                    
1        0            0        0                                          
2        0            1        1                                          
3        1            0        1                                          
4        1            1        0                                          
______________________________________                                    
 
    
     From the table, it can be seen that both states 2 and 3 will cause the detector 56 output to be high. When line 52 changes voltage level, the inputs to gate 66 will be at the same logic level for a short period of time (states 1 or 4). While the inputs are in this state, the output of detector 56 will go low. This creates a pulse on output line 70 of the detector on both positive and negative transitions of line 52. The pulse width is determined by the propagation delay of inverter 68 and the charge time of capacitor 72. The timing of this pulse is shown in FIG. 9, parts (a) and (b). 
     The detector 56 output is applied over lines 74 and 76 respectively to latch 58 and timer 60. When the detector output goes low, as is seen in part (b) of FIG. 9, it resets the timer, causing the output of the timer on line 84 to go low for a preselected time period T, as is shown in part (c) of FIG. 9. The detector output also provides a clock signal on line 74 for latch 58. On the positive edge of the pulse, the output of the latch will go high, as is seen in part (d) of FIG. 9. The output of the latch provides a control signal on line 78 for analog switch (SW) 62. When the latch 58 output goes high, analog switch 62 is enabled. This event passes the clock input on line 64 through the switch to the timer over line 80 and to other circuitry (the active tag circuitry) over line 82. This event is seen in part (e) of FIG. 9. 
     Once the clock input is applied to the timer, the timer begins to count. If another pulse is thereafter generated by transition detector 56, the timer will be reset and will restart its count, as is the case in the showing of FIG. 9. If there is no motion for the time period set, the timer will overflow, causing the output of the timer to go high. This resets the latch and causes the output of the latch to go low. Once the output of the latch goes low, the analog switch is disabled and this event disconnects the clock input from the timer and the active tag circuitry. Where that circuitry is CMOS, its current consumption is directly proportional to the clock frequency on line 82. The invention, by disabling the clock, substantially reduces battery loading. A substantially greater life expectancy is thus afforded by apparatus of the invention. 
     Evidently, where there is the condition of continuing resetting of the timer, motion being sustained, the active circuitry of the tag is enabled to receive and decode incident messages, such as is disclosed in the &#39;513 patent. 
     By way of summary, the invention will be seen to provide an EAS tag inclusive of an electrical power source contained with the tag and circuitry powered by the electrical power source and a motion sensor operatively associated with the tag and contained therewith, the motion sensor providing output indication of movement and thereupon effecting loading of the the electrical power source by such tag circuitry. 
     The motion sensor comprises first and second housings of electrically conductive material, first and second electrically conductive elements movably supported respectively in the first and second housings, and a joinder member for mechanical interconnection of the first and second housings, the joinder member being comprised of electrically insulative material to electrically isolate the housings from one another and defining a passage permitting movement of the first and second electrically conductive means between the first and second housings responsively to orientation of the tag. The joinder member, the housings and the first and second electrically conductive elements are collectively dimensioned to provide for electrical conductivity between the first and second housings upon reorientation of the tag from a disposition wherein neither of the first and second electrically conductive elements is in registry with the joinder member to other disposition. 
     The detection circuitry will be seen to include a detector unit connected to one of the housings to selectively generate an output signal indicative of motion of the apparatus, a switch operative on such detection means output signal generation to conduct clock pulses therethrough to the other circuitry, and a timer advanced by the clock pulses conducted through the switch. The timer has a predetermined pulse count capacity and is connected to the detection unit to receive the detection unit output signal and to thereby be reset to zero count. The timer is operative to render the switch inoperative to conduct clock pulses therethrough on counting pulses in excess of the predetermined count capacity thereof. A latch is connected to the detection unit to receive the detection unit output signal, the latch thereupon rendering the switch operative to conduct the clock pulses therethrough. The latch is connected to the timer to receive indication therefrom of the counting of pulses in excess of the predetermined count capacity thereof, the latch being connected to the switch to render the switch inoperative to conduct the clock pulses therethrough upon receiving such excess count indication from the timer. 
     As contrasted with unsealed sensors of the prior art with attendant ingress of contaminants, joinder member 40 is configured as shown as a snap ring tightly engaging the cup housing members. 
     Further, a high degree of mobility if afforded spheres 36 and 38 in the passage collectively defined by the housings and the joinder member. 
     Various changes may evidently be introduced in the foregoing structure without departing from the invention. For example, the number of spheres employed may be of number exceeding the two spheres in the preferred embodiment. Thus, the particularly described and preferred embodiment is intended to be illustrative and not limiting of the invention. The true spirit and scope of the invention is set forth in the appended claims.