United States Patent (19)
`Plonsky et al.
`
`11) Patent Number:
`45) Date of Patent:
`
`5,049,857
`Sep. 17, 1991
`
`(54)
`
`(75)
`
`(73)
`
`(21)
`22)
`(51)
`(52)
`(58)
`
`MULTI-MODE ELECTRONIC ARTICLE
`SURVEILLANCE SYSTEM
`
`Inventors: Christopher B. Plonsky, Boynton
`Beach; Harry E. Watkins, Boca
`Raton; Marco A. Paez, Wellington,
`all of Fla.
`Assignee: Sensormatic Electronics Corporation,
`Deerfield Beach, Fla.
`Appl. No.: 384,556
`
`Filed:
`
`Jul. 24, 1989
`
`Int. Cl. .............................................. G08B 13/24
`U.S. Cl. .................................... 340/551; 340/572;
`455/78
`Field of Search ............... 340/551, 572, 522, 516,
`340/825.7-825.72, 505, 825.54; 455/78
`
`(56)
`
`References Cited
`U.S. PATENT DOCUMENTS
`3,859,624 1/1975 Kriofsky et al................. 340/572 X
`4,779,076 10/1988 Weaver ............................... 340/551
`4,791,412 12/1988 Brooks ................................ 340/572
`4,797,659 1/1989 Larsen ................................. 340/572
`Primary Examiner-Glen R. Swann, III
`Assistant Examiner-Thomas J. Mullen, Jr.
`Attorney, Agent, or Firm-Robin, Blecker, Daley &
`- Driscoll
`ABSTRACT
`57
`. A magnetic article surveillance system in which surveil
`lance is carried out by operating the system in first and
`second different modes of a magnetic transmitting and
`receiver means in order to make a determination as to
`the presence of an article in the zone.
`
`62 Claims, 8 Drawing Sheets
`
`
`
`
`
`DETECTION
`ASSEMBLY
`
`Ex.1009
`APPLE INC. / Page 1 of 22
`
`

`

`U.S. Patent
`U.S. Patent
`
`Sep. 17, 1991
`Sep. 17, 1991
`
`Sheet 1 of 8
`Sheet 1 of 8
`
`5,049,857
`5,049,857
`
`So
`O
`Q
`tT
`CN
`a
`
`N
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`
`
`
` ASSEMBLY
`
`Ex.1009
`APPLEINC./ Page 2 of 22
`
`Ex.1009
`APPLE INC. / Page 2 of 22
`
`

`

`U.S. Patent
`
`Sep. 17, 1991
`
`Sheet 2 of 8
`
`5,049,857
`
`27
`
`MUX
`
`A
`
`D
`E
`
`2ND HARMONIC
`CHANNEL
`
`3ND HARMONIC
`CHANNEL
`Tx CURRENT it
`TX CURRENT 3:2
`
`28
`
`A/D
`CONVERTER
`
`
`
`260
`MUX
`ADDRESS
`26d
`TX/RX CONTROL
`CONTROLLERTx CURRENT CONTROL
`
`FUNDAMENTAL-29
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`
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`
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`PART OF PEDESTAL $1
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`A/G. 2
`
`Ex.1009
`APPLE INC. / Page 3 of 22
`
`

`

`U.S. Patent
`
`Sep. 17, 1991
`
`Sheet 3 of 8
`
`5,049,857
`
`START
`
`
`
`-NITIALZE INTERNAL
`PORTS, REGISTERS,
`TIMERS, EXTERNAL
`PORTS AND INTERRUPTS
`-SET TX. CURRENTS AND
`FREQUENCY DEFAULTS
`
`O
`
`SELECT XCVR MODE - O2
`ANE) SET TXI = 8 A.
`
`FUND, SETTLING
`S = 4 OO MS.
`
`O3
`
`READ FUNDAMENTAL
`LEVEL AND STORE
`
`O4
`
`READ FUNDAMENTAL
`PHASE AND STORE
`
`O5
`
`SET TXS TO A
`MNMUM LEVEL
`
`SELECT SINGLE
`RCVR/XMTR MODE
`
`O6
`
`O7
`
`FOR
`ADJUST TX.
`SELECTED PEDESTAL
`SEPARATION
`
`O8
`
`FILTERS SETTLING
`8 = |OO MS.
`
`O9
`
`READ NOSE LEVELS
`FROM SYSTEM
`
`O
`
`A/G. 3
`
`Ex.1009
`APPLE INC. / Page 4 of 22
`
`

`

`U.S. Patent
`
`Sep. 17, 1991
`
`Sheet 4 of 8
`
`5,049,857
`
`START INT
`
`SECONDS
`ELASE9
`
`2O2
`
`
`
`
`
`28
`3RD NN
`6Ni, OS2
`p
`
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`224
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`3RD CNT = O 3RD CNT=5O
`
`219
`
`22
`
`A
`ES5
`CRTERA
`
`A/G. 44
`
`Ex.1009
`APPLE INC. / Page 5 of 22
`
`

`

`U.S. Patent
`
`Sep. 17, 1991
`
`Sheet 5 of 8
`
`5,049,857
`
`
`
`
`
`
`
`
`
`
`
`NT CNTR=
`NT CNTR-- O
`
`
`
`23
`
`NT CNTR=
`NT CNTR - O
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`i. SET
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`AMPTUDE
`
`
`
`227
`226
`1ST 1MNESPHSE SETTLING
`LOOP r S=3OO MS
`p
`
`228
`
`READ FUND
`PHASE
`
`
`
`229
`
`HAS FUND
`AMPLTUDE
`CHANGED
`p
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`23O
`YES/AAS FUND
`PHASE
`CHANGED
`p
`
`
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`23
`
`READ
`3RD HAR
`
`READ
`2ND HAR
`
`TIME THRU
`
`2ND OR
`3RD) V.
`2
`
`
`
`SYSTEM )
`5OMS
`
`- NULL TX 8. TX2
`- SWITCH TO TX/RX
`-SET TX=7A.
`
`-NULL X11 8 TXI2
`-SWITCH TO TX/RX
`-SET TXI = 7A.
`
`238
`
`235
`
`
`
`HASSIANELS
`S = 4OO MS
`
`
`
`237
`
`END INT.
`
`A/G. 4A
`
`Ex.1009
`APPLE INC. / Page 6 of 22
`
`

`

`U.S. Patent
`
`Sep. 17, 1991
`
`Sheet 6 of 8
`
`5,049,857
`
`27
`
`MUX
`
`
`
`A
`
`D
`
`
`
`28
`
`
`
`
`
`2ND HARMONIC
`CHANNEL
`
`
`
`3RD HARMONIC
`CHANNEL
`TX CURRENT :4
`TX CURRENT : 2
`
`
`
`
`
`.
`CONVERTER)
`26
`ADDRESS
`RX CONTROL: 2
`RX CONTROL:
`CONTROLLERTX CURRENT CONTROL
`
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`PEDESTAL:2
`--S2-Nc
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`OSCLLATOR
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`(90 DEGREES)
`
`POWER AMP
`: 2
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`
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`A
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`RESONATNG
`
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`C
`
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`R
`
`Ex.1009
`APPLE INC. / Page 7 of 22
`
`

`

`U.S. Patent
`U.S. Patent
`
`Sep. 17, 1991
`Sep. 17, 1991
`
`Sheet 7 of 8
`Sheet 7 of 8
`
`5,049,857
`5,049,857
`
`220
`
`2la
`
`6la:
`
`:
`
`24a
`
`230
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`|
`
`+
`
`62a
`
`FIG. 7
`
`Ex.1009
`APPLEINC./ Page 8 of 22
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`Ex.1009
`APPLE INC. / Page 8 of 22
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`

`

`US, Patent
`U.S. Patent
`
`Sep. 17, 1991
`Sep. 17, 1991
`
`Sheet 8 of 8
`Sheet 8 of 8
`
`5,049,857
`5,049,857
`
`FIG. 8
`
`
`
`2la
`
`|
`
`220
`
`|
`
`24a
`
`Pre.
`
`yd]. ,
`|i
`
`FIG. 9
`
`Ex.1009
`APPLEINC./ Page 9 of 22
`
`Ex.1009
`APPLE INC. / Page 9 of 22
`
`

`

`1
`
`MULTI-MODE ELECTRONIC ARTICLE
`SURVELLANCE SYSTEM
`
`5
`
`O
`
`15
`
`5,049,857
`2
`this spacing defines the system width), there is a rela
`tively low coupling of magnetic energy therebetween.
`In using the transmit/receive system, it has been
`found that acceptable pick rates are achievable and that
`low false alarm rates are also achievable, but only for
`objects with low masses such as, for example, deacti
`vated tags and watches. This low false alarm rate for
`low mass objects is due to the aforementioned low cou
`pling between the transmitter and receiver coils. Such
`low coupling causes the receiver coil sensitivity to be
`relatively low in areas where the transmitted energy is
`high. Hence, received energy due to low mass objects is
`usually insufficient to meet the criteria established for
`determining the presence of articles carrying valid tags.
`However, even with this low sensitivity of the receiver
`coil, high mass objects are found to generate sufficient
`received energy to meet these criteria, thereby causing
`false alarms.
`A second category of system used for magnetic arti
`cle surveillance is referred to as a "transceiver" system.
`In this type of system, transmitter and receiver coils are
`housed in common pedestals at each of a number of
`locations bordering the interrogation zone. Because of
`this common housing of the transmitter and receiver
`coils in close proximity to each other, there is a high
`coupling of magnetic energy therebetween.
`In using the transceiver system, it has been found that
`the system provides a good pick rate for articles carry
`ing single tags. It has also been found that the system
`provides a relatively low false alarm rate, but only for
`high mass objects such as, for example, shopping carts.
`This low false alarm rate for high mass objects occurs
`because of the high coupling between the transmitter
`and receiver coils. This coupling causes the receiver
`coil to be highly sensitive in the same areas where the
`transmitter energy is high. As a result, in the presence of
`high mass metal objects, the received energy becomes
`sufficient to meet the criteria established for identifying
`metal objects, before the criteria for identifying articles
`carrying valid tags are met. The high mass objects can
`thus be detected before the system alarms.
`The transceiver system, however, provides a rela
`tively higher false alarm rate for low mass objects, e.g.,
`deactivated tags, watches, etc. Low mass objects are
`found to result in sufficient received energy to meet the
`criteria for identifying articles carrying valid tags, be
`fore the criteria for metal objects are met. Hence, the
`system is likely to false alarm for these low mass objects.
`The transmit/receive and the transceiver systems can
`be modified in certain conventional ways to attempt to
`enhance their operation. Thus, to decrease false alarms
`and sensitivity to fixed metal objects, the transmitted
`energy can be decreased by decreasing the current to
`the transmitter coil. Decreasing the transmitted energy,
`however, decreases the system width and/or pick rate.
`Also, the criteria for differentiating between received
`signals indicative of articles carrying valid tags and
`those indicative of other metal objects can be varied or
`changed to provide some limited improvement in the
`pick and false alarm rates. Finally, placing more than
`one tag in an article can be used to increase the pick
`rate.
`The above techniques for enhancing system opera
`tion have thus provided only limited improvement in
`System performance. Hence, there is still a need for a
`System which can provide a relatively wide system
`
`25
`
`30
`
`35
`
`BACKGROUND OF THE INVENTION
`This invention relates to electronic article surveil
`lance systems and, in particular, to electronic article
`surveillance systems in which magnetic radiation or
`energy is used to carry out the article surveillance.
`Electronic article surveillance systems are known in
`the art wherein surveillance is carried out by transmit
`ting a magnetic field into an interrogation zone. In these
`systems, determining the presence of the articles under
`surveillance is accomplished by sensing perturbations to
`the transmitted magnetic field. These perturbations are
`generated by tags attached to or incorporated into the
`articles. These tags carry or are formed frpm magnetic
`markers or materials which create the perturbations.
`In designing article surveillance systems of this type,
`attention is focused on achieving certain characteristics
`20
`or criteria which are of importance to the user. One
`characteristic is referred to as the system "width." This
`characteristic defines the maximum width of the inter
`rogation zone which can be used, while still detecting
`articles carrying valid tags with reliability. It is desir
`able that the system width be maximized so as to give
`the widest possible interrogation zone. This makes the
`surveillance system adaptable to a greater number of
`user locations.
`A second characteristic is referred to as the system
`"pick." This is a measure of the percentage of time that
`the system identifies articles bearing valid tags. It is
`important that this characteristic also be maximized in
`order for the system to operate credibly as a surveil
`lance system.
`A third characteristic is the system "false alarm' rate.
`This characteristic is a measure of the percentage of
`time the surveillance system alarms as a result of objects
`other than articles carrying valid tags. Frequently, false
`alarms are brought about by metal objects such as shop
`ping carts or watches passing through the interrogation
`zone. It is essential that the false alarm rate of the sur
`veillance system be minimized to likewise promote sys
`tem credibility as well as to avoid embarrassment to the
`user of having the system alarm for objects other than
`45
`those under surveillance.
`Other characteristics of the surveillance system of
`interest to the user involve the ability of the system to
`operate properly with tags which are deactivatable and
`with fixed metal objects in the floors, walls and other
`50
`equipment in or bordering the interrogation zone. In the
`case of deactivatable tags, it is desired that the system
`alarm only for articles carrying tags which are in their
`active state. In the case of fixed metal objects, it is de
`sired that the system be substantially immune to the
`55
`otherwise masking effects of these objects.
`The magnetic article surveillance systems designed to
`date have had difficulty in achieving all these character
`istics. These systems generally fall into two categories.
`In one category of system, the antenna or coil used to
`60
`transmit the magnetic field into the interrogation zone
`(the "transmitter coil') and the antenna of coil which
`receives magnetic energy from the zone (the "receiver.
`coil") are disposed in spaced housings or pedestals
`which border the interrogation zone. This category of
`65
`system is referred to as a "transmit/receive' system.
`Because of the spacing between the transmitter and
`receiver coils of the transmit/receive system (usually
`
`Ex.1009
`APPLE INC. / Page 10 of 22
`
`

`

`5
`
`-
`5,049,857
`3
`width, a relatively high pick rate and a relatively low
`false alarm rate for objects of low and high masses.
`It is therefore an object of the present invention to
`provide an electronic article surveillance system having
`enhanced performance.
`It is a further object of the present invention to pro
`vide an enhanced electronic article surveillance system
`which utilizes magnetic energy and tags employing
`magnetic markers.
`It is a further object of the present invention to pro
`10
`vide a magnetic electronic article surveillance system in
`which the system false alarm rate can be relatively low
`for objects of different masses.
`It is yet a further object of the present invention to
`provide a magnetic electronic article surveillance sys
`tem in which the system false alarm rate can be rela
`tively low for objects of high and low masses and in
`which the system width and pick rate can be relatively
`high.
`
`4.
`transmitter and first and second receivers are in their on
`or active states.
`In this embodiment, the system also preferably com
`prises a second transmitter whose coupling to the re
`ceivers is such that the coupling of magnetic energy
`between the second transmitter and the second receiver
`is greater than that between the second transmitter and
`the first receiver. The second means controls the second
`transmitter such that it is in its off or inactive state dur
`ing the first mode of operation and such that it is in its
`on or active state during the second mode of operation.
`With the system configured as above, the system is
`operated by the second means in its first mode of opera
`tion, which is a transmit/receive mode, and the system
`makes a first determination in accordance with a first set
`of criteria as to the presence in the interrogation zone of
`an article bearing a valid tag. If these criteria are met,
`the second means then switches the system to the sec
`ond mode of operation, which is a transceiver mode,
`and the second means makes a second determination in
`accordance with a second set of criteria as to the pres
`ence of the article. If these second criteria are also met,
`the system alarms indicating the presence of the article
`in the interrogation zone.
`In the embodiments of the invention to be disclosed
`hereinafter, the first set of criteria are based upon the
`level of one or more frequency components in the re
`ceived magnetic energy. These frequency components
`are those at predetermined harmonics of the fundamen
`tal frequency of the magnetic energy transmitted into
`the interrogation zone. The second criteria, in turn, are
`dependent upon the level and/or phase of the received
`energy component at the fundamental frequency in
`relationship to the level and/or phase of the transmitted
`energy at such frequency.
`Also, in these embodiments, the second means con
`trols the transmitters such that during the first or trans
`mit/receive mode the first transmitter transmits a field
`of lower level than that transmitted by each of first and
`second transmitters during the second or transceiver
`mode. Further, the second means provides predeter
`mined delays at preselected times in order to ensure
`proper operation and stabilization of the system compo
`nents. The system is additionally provided with an ini
`tialization and recalibration procedure which allows the
`system to calibrate and recalibrate ambient conditions
`and adjust criteria thresholds during operation.
`In a first embodiment of the invention to be disclosed
`hereinafter, a single relay contact switch is used to
`jointly control the second transmitter and second re
`ceiver and to switch the components between their
`respective on and off states. In a second embodiment,
`circuitry is provided which allows independent control
`of the on and off states of each of the transmitters and
`receivers.
`BRIEF DESCRIPTION OF THE DRAWING
`The above and other features and aspects of the pres
`ent invention will become more apparent upon reading
`the following detailed description in conjunction with
`accompanying drawings, in which:
`FIG. 1 shows the general configuration of a magnetic
`article surveillance system in accordance with the prin
`ciples of the present invention;
`FIG. 2 shows a first embodiment of the system of
`FIG. 1 in greater detail;
`
`5
`
`SUMMARY OF THE INVENTION
`In accordance with the principles of the present in
`vention, the above and other objectives are realized in
`an article surveillance system which is provided with a
`first means for transmitting magnetic energy into an
`25
`interrogation zone and for receiving magnetic energy
`including energy from the zone. The first means has at
`least first and second modes of operation and a second
`means responsive to the first means is provided to con
`trol the first means such that it operates in at least the
`first and second modes of operation in order to make a
`determination as to the presence of an article bearing a
`tag. By using the two modes of operation of the first
`means before the system can make a determination of
`article presence, the system is able to have a high pick
`35
`rate, a high system width and a low false alarm rate.
`The first and second modes of operation of the first
`means can be made different by utilizing different en
`ergy transmitting and/or energy receiving characteris
`tics in each mode. These differences in characteristic
`can be realized by changing the transmitting field ampli
`tude or frequency or by using a multiple of transmitted
`frequencies. These effects, in turn, can be brought
`about, in part, by using one or more transmitters in the
`first means and selectively activating the transmitter
`45
`antennae. The differences in characteristic can also be
`brought about by changing with one or more of the
`latter changes or alone, the sensitivity of the first means
`to the magnetic energy. This sensitivity change can be
`realized by using one or more receivers and changing
`50
`the receiver sensitivity by selectively activating the
`receiver antennae or modifying the gain of the receiver
`electronics.
`In the embodiment of the invention to be disclosed
`hereinafter, the first means includes a first transmitter
`for transmitting magnetic energy into the interrogation
`zone and first and second receivers which are adapted
`to receive magnetic energy including energy from the
`zone. The first and second receivers are coupled to the
`transmitter such that the coupling of magnetic energy
`between the first transmitter and the first receiver is
`greater than the coupling of magnetic energy between
`the first transmitter and the second receiver. The sec
`ond means selectively operates the transmitter and re
`ceivers to achieve the first and second modes. In the
`65
`first mode, the first transmitter and second receiver are
`in their on or active states, while the first receiver is in
`its off or inactive state. In the second mode, the first
`
`-
`55
`
`Ex.1009
`APPLE INC. / Page 11 of 22
`
`

`

`O
`
`15.
`
`5,049,857
`5
`6
`FIG. 3 shows a flow diagram of the system operation
`mitters 21, 22 and the receivers 23 and 24 to establish
`carried out by the controller of FIG. 2 during an initial
`and switch between first and second modes of operation
`ization phase of operation of the system;
`for the system. In the first mode of operation, the trans
`FIGS. 4A and 4B show a flow diagram of the system
`mitter 21 and receiver 24 are in their active states and
`operation carried out by the controller of FIG. 2 during
`the transmitter 22 and receiver 23 are in their inactive
`a surveillance phase of operation of the system; and
`states and in the second mode of operation both trans
`FIG. 5 illustrates the details of a second embodiment
`mitters 21, 22 and both receivers 23 and 24 are in their
`of the system of FIG. 1.
`active states.
`The first mode of operation is thus a transmit/receive
`FIGS. 6-9 show further transmitter and receiver.
`configurations which can used in the system of FIG. 1.
`mode (relatively low magnetically coupled transmitter
`and receiver in operation) and the second mode of oper
`DETAILED DESCRIPTION
`ation is a transceiver mode (relatively high magnetically
`FIG. 1 shows the overall general configuration of an
`coupled transmitters and receivers in operation). By
`appropriately switching between these modes of opera
`article surveillance system 1 in accordance with the
`principles of the present invention. The system 1 is to be
`tion and by utilizing specified different article detection
`employed to detect the presence of an article 2 passing
`criterion in the two modes, as will be discussed below,
`through an interrogation zone 3.
`the aforementioned high pick rate and low false alarm
`This is accomplished by providing each article with a
`rate for objects of different masses for the system 1 is
`tag 4 formed from or comprised of a magnetic marker 5.
`achieved.
`The marker 5 can comprise any one of a number of
`As can be seen in FIGS. 1 and 2, the transmitter 21
`20
`magnetic materials in strip, wire or other form having
`and receiver 23 are provided with respective transmit
`the capability of creating perturbations in a magnetic
`ter and receiver coils 21a and 23a. These coils are both
`arranged in close proximity in the pedestal 6 to achieve
`field transmitted into or established in the zone 3. Pref
`erably, the magnetic material is such as to create pertur
`the desired high magnetic coupling between the trans
`bations at harmonics of the fundamental frequency Foof
`mitter 21 and receiver 23,
`25
`the transmitted field. Typical magnetic materials might
`Likewise, the transmitter coil 22a of the transmitter
`be permalloy and super permalloy. Also, magnetic ma
`22 and the receiver coil 24a of the receiver 24 are ar
`terials exhibiting a large Barkhausen discontinuity such
`ranged in close proximity in the pedestal 7. This pro
`as disclosed in U.S. Pat. No. 4,660,025, assigned to the
`vides the desired high magnetic coupling between
`same assignee hereof, might also be used. The magnetic
`transmitter 22 and receiver 24. Also, transmitter coil
`30
`marker 5 may also be configured to be deactivatable in
`22a and receiver coil 23a are spaced by the system
`accordance with known practices.
`width, i.e., the spacing between the pedestals 6, 7, the
`Magnetic energy is transmitted into the zone 3 via
`transmitter 21 and receiver 24 and the transmitter 22
`and receiver 23 have a relatively low magnetic coupling
`one or more magnetic field transmitter coils. These coils
`are housed in and distributed amongst one or more
`as is desired for these transmitter/receiver pairs.
`35
`pedestals, shown as pedestals 6 and 7, bordering the
`For driving the transmitters 21 and 22, a common
`zone 3. Similarly, magnetic energy, including the per
`master oscillator 25 provides A-C drive signals at a
`turbation energy created by the presence of any mark
`fundamental frequency Fo. The drive signals are fed
`through respective digital potentiometers 21b and 22b,
`ers 5 in the zone 3, is received by one or more magnetic
`which permit adjustment of the signal levels, and
`field receiver coils. These coils are also housed and
`distributed amongst the pedestals 6 and 7.
`through respective power amplifiers 21c, 22c which
`A control system and detection assembly 8 provides
`convert the A-C voltages to high level output voltages
`overall control of the operation of the system 1. This
`for the respective coils 21a and 22a. Between the poten
`assembly, in response to the transmitted and received
`tiometer 22b and amplifier 22c, a 90° phase-shifter 22d is
`magnetic energy, makes a determination as to the pres
`provided for shifting the phase of the output of the
`45
`ence in the zone 3 of articles 2 bearing tags 4 having a
`potentiometer 22b by 90. The coils 21a and 22a are thus
`driven in phase quadrant resulting in magnetic fields in
`valid markers 5 (i.e., valid articles). When a valid article
`is detected, the assembly 8 activates the alarm 9 to indi
`the zone 3 which are also in phase quadrant.
`cate presence of the article.
`In the FIG. 2 embodiment, the receiver coils 23a and
`In accordance with the principles of the present in
`24a are connected electrically in series. This results in a
`50
`vention, the configuration and arrangement of the one
`combined received signal being developed when both
`or more magnetic transmitters and receivers in the sys
`receivers are active.
`ten 1 and the control of the operation of same by the
`For effecting the first and second operating modes,
`the FIG.2embodiment is provided with a contact relay
`control and detection assembly 8 to provide different
`modes of operation is such that the pick rate for the
`K1 having relay parts K11 and K12. The relay part K11
`system 1 is relatively high, while the false alarm rate for
`is connected in circuit with the receiver coil 23a and the
`the system is relatively low for metallic objects of both
`relay part K12 is connected in circuit with the transmit
`high and low masses. More particularly, this is achieved
`ter coil 22a.
`in the FIG. 2 embodiment of the system 1 by including
`Each relay part has two states X and Y which are
`in the system at least a first transmitter 21 and, prefera
`controlled by a common relay coil L1. In the X state of
`bly, also a second transmitter 22, and, furthermore, a
`relay part K11, the relay part shunts the coil 23a,
`first receiver 23 which is more closely coupled magneti
`thereby rendering the receiver 23 inactive. In its Y state,
`cally to the first transmitter 21 than to the second trans
`the relay part K11 opens this shunt, thereby rendering
`mitter 22 and a second receiver 24 which is more
`the receiver 23 active. Likewise, the relay part K12
`closely coupled magnetically to the second transmitter
`renders the transmitter 22 inactive in its X state, by
`65
`22 than to the first transmitter 21. It is further achieved
`opening the connection of the transmitter coil 22a and
`in the FIG. 2 embodiment by the assembly 8 controlling
`ground, and renders the transmitter 22 active in its Y
`the on and off or active and inactive states of the trans
`stat by closing this connection to ground.
`
`55
`
`Ex.1009
`APPLE INC. / Page 12 of 22
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`15
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`20
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`5
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`O
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`5,049,857
`7
`8
`As can be appreciated, by controlling the current to
`signal on line 26a, the controller 26 provides transmitter
`the coil L1 of the relay K1, the transmitter 22 and the
`current control signals on lines 26b, 26c to the digital
`potentiometers 21b and 22b. These signals control the
`receiver 23 can be rendered active and inactive. This
`enables the system 1 to be placed in the first operating
`current levels in the transmitter antenna coils 21a and
`22a, respectively. The controller also generates a mode
`mode (transmitter 21 and receiver 24 active, transmitter
`control signal on the line 26d for addressing the relay
`22 and receiver 23 inactive) and in the second operating
`node (both transmitters 21 and 22 and both receivers 23
`coil L. This signal controls the state of the relay K1
`and, therefore, the active or inactive states of the trans
`and 24 active).
`As above-discussed, the control assembly 8 of the
`mitter 22 and rcceiver 23.
`system 1 brings about the first and second operating
`The operation of the system 1 is carried out by the
`modes of the system 1. In the FIG. 2 embodiment, the
`controller 26 in accordance with program control. This
`assembly 8 comprises a controller 26 which, preferably,
`operation includes an initialization phase where the
`is in the form of a program controlled microcomputer.
`conditions of the environment of the system are used to
`The controller 26 develops the necessary control sig
`initially calibrate the system, i.e., develop initial or base
`nals for controlling the system 1 as well as processes
`levels for system parameters including thresholds for
`information received from the receivers 23, 24 and
`detection criteria. It also includes a surveillance phase
`where the system operates to evaluate the presence of
`transmitters 21, 22 to make a determination as to the
`presence of a valid article in the zone 3.
`valid articles in the interrogation zone.
`FIG. 3 shows a flow diagram of an illustrative initial
`The controller 26 receives the aforesaid information
`ization phase of operation of system 1. This operation is
`from the transmitters and receivers by addressing, via
`carried out when the system is first powered up. As
`an address line 26a, ports A-E of a multiplexer circuit
`27. The multiplexer circuit 27 feeds the signal of an
`indicated, at this time, the controller proceeds to step
`addressed port to the controller 26 through an A/D
`101 where it initializes its internal registers, timers, in
`terrupts, and external input/output ports. This places
`converter 28 which converts the signal to a digital sig
`nal, typically a binary encoded signal, which can be
`the controller 26 in operating condition.
`25
`read by the controller.
`Once the controller 26 is initialized the controller in
`As indicated in FIG. 2, the multiplexer signals at
`step 102 sets the system 1 to operate in the second or
`ports D and E are indicative of the current in the trans
`transceiver mode at a preselected transmission level.
`mitter coils 21a and 22a, respectively at the fundamental
`This is brought about by the controller 26 providing a
`frequency Fo. These signals are developed by an ar
`signal on the line 26d to the coil Ll of the relay Kl,
`30
`rangement of a capacitor, resistor and current sensing
`thereby placing the relay parts K11 and K12 in their Y
`amplifier connected to each coil (identified as C1, R1
`states. As a result, both transmitters 21, 22 and both
`and A1 and C2, R2 and A2 in FIG. 2).
`receivers 23, 24 are placed in their active states.
`The multiplexer ports A, B and C, in turn, receive
`The controller then signals, via lines 26b, 26c, the
`signals indicative of the components of the received
`digital potentiometers 21b and 22b, adjusting them until
`magnetic signals at the fundamental frequency, second
`the current through each transmitter coil 21a and 22
`harmonic and third harmonic, respectively, of the trans
`reaches a predetermined first current level, shown as
`mitted magnetic energy. Thus, these signals are indica
`8Ap-p. The transmitter coil currents are read during
`tive of the received components at the frequencies Fo,
`this adjusting operation through the A/D converter 28
`2Fo and 3Fo, respectively.
`by the controller addressing the multiplexer ports D
`The component of the received signal at the funda
`and E. Once the currents have reached the 8Ap-p level,
`mental frequency Fois developed by coupling a portion
`the controller 26 proceeds to step 103 where it waits a
`of the received energy through a bandpass filter (BPF)
`preselected time, shown as 400 msec, for stabilization of
`the system 1 components, particularly the fundamental
`29 whose pass band is centered at the fundamental fre
`quency Fo. This filter extracts the component at the
`BPF 29.
`45
`fundamental Fo, amplifies this component and then
`The controller 26 then proceeds to step 104 where it
`makes it available to the port A of the multiplexer 27.
`addresses port A of the multiplexer 27 to read through
`A second bandpass filter (BPF) 31 receives a second
`the A/D converter the amplitude of the fundamental
`portion of the received signal and it extracts from this,
`component in the composite signal received by the
`signal the components thereof at the second and third
`receiver coils 23a and 24a. Since the waveform from the
`50
`harmonics 2F0 and 3Fo. The extracted components are
`BPF 29 is an A-C signal, the controller 26 address the
`then separated by channel separators 32, 33, which are
`port A several times to samp