Abstract:
A two-dimensional array of magnetomechanical markers (20) is adhered to a continuous web (62). A magnetizer element (70) is scanned (74) across the web (62) to magnetize the bias elements in a group of markers (20) with a first polarity, thereby activating the group of markers. The web (62) is then advanced (68) and the magnetizer (70) is scanned across the web in an opposite direction (76) to the previous scan to magnetize the bias elements of a second group of the markers (20) with a second polarity, thereby activating the second group of markers. The web (62) is slit in a longitudinal direction to produce web-strips each carrying a column of the activated markers. The web-strips are rolled to form marker roll assemblies each having about half the bias elements magnetized with a first polarity and the remaining bias elements magnetized with an opposite polarity. The roll of activated markers forms no more than a minimal "leakage" magnetic field.
Abstract:
In accordance with the present invention there is provided an apparatus for deactivating electronic article surveillance tags comprising a deactivation coil (132), a capacitor (118), charging means for charging the capacitor (118) to a predetermined level, and an electronic switch (130) connected to the capacitor (118) and the deactivation coil (132) so that when the switch (130) is open the capacitor (118) can be charged by the charging means and when the switch (130) is closed the capacitor (118) can discharge through the deactivation coil (132).
Abstract:
A material used to form a biasing element (16) for a magnetomechanical EAS marker (10) has a coercivity that is lower than the coercivity of biasing elements used in conventional magnetomechanical markers. The marker (10) formed with the low coercivity material can be deactivated by applying an AC magnetic field at a level that is lower than is required for deactivation of conventional markers (curve 26). The marker (10) with the low coercivity bias element (16) can also be deactivated when at a greater distance from a deactivation device than was previously practical.
Abstract:
An electronic article surveillance system (100) includes a signal generator (22, 24, 26) for generating an interrogation signal (28) in an interrogation zone (30), an antenna (36) which receives a signal (34) present in the interrogation zone (30), and circuitry for cancelling interference. A hybrid interference component cancelling loop forms a digital interference estimate signal (108) which is converted (106) into an analog estimate signal, which is subtracted (102) from an input analog signal (40). The difference signal is digitized and subjected to additional digital interference cancellation processes (108). Each of the signal processing operations (108) entails performing a polyphase decomposition of a digital input signal, estimating a mean value of each of the resulting subsequences, and combining the estimated mean values to form an interference component estimate signal. An input sample window for a comb-filtering stage is phase adjusted relative to the interrogation signal to compensate for changes in phase of the marker signal (34).
Abstract:
An EAS central station (2) has a number of input/output ports (2A-2D) each for interfacing with a different personality local station (3-6). Hardware equipment (2F) and software programming (2G) of the central station (2) have parts associated with the different personality local stations (3-6) and a central processing unit (2E) selects the part of the hardware equipment (2F) and software programming (2G) associated with a local station (3-6).
Abstract:
An EAS system (1) employing a central station (6) having a central processing unit (7) and a local station (8) having a microcontroller (9) and in which the functions necessary for detecting the EAS tag (5) signals and generating alarms (13) are shared by the central station and the local station. A switch (14A-14D) is further provided at the local station for automatically reconfiguring the receiver antennas (3A-3H) based on antenna configuration instructions generated at the central station responsive to certain conditions at the location (2) being monitored.
Abstract:
An electronic article surveillance marker (32) is mounted in a bottle cover (10') which covers the top (44) and neck of a bottle (40) to be protected from theft. The cover (10') is formed by rolling a pre-cut sheet of foil (10) or similar material. Overlapping edge portions of the rolled sheet are attached to each other by an adhesive layer (30). The marker (32) is mounted on the adhesive layer (30) so that it is held between the overlapping edge portions of the sheet and is aligned with a seam (40) formed by the overlapping edge portions.
Abstract:
A video camera (20) is operated to obtain a very rapid change in magnification. A target degree of magnification is achieved by rapid change in an electronic zoom factor provided by an image signal processing circuit (28). Either before or after the change in electronic zoom factor, simultaneous off-setting changes are carried out in the electronic zoom factor and in a mechanical zoom factor provided by the camera's optical system (22). The simultaneous off-setting changes in the two zoom factors occur at a rate consistent with practical operation of the mechanical drive components for the camera's optical system.
Abstract:
A video surveillance system (10) has a camera equipped with a fisheye lens (20) having a substantially hemispheric field of view. The system (10) implements operations equivalent to pan, tilt, and zoom of a conventional camera. The camera produces a distorted fisheye image due to the properties of the fisheye lens (20). The system (10) corrects the distortion by mapping the pixels of the fisheye image to coordinates produced by selecting a particular part of the fisheye image to be viewed. The fisheye image formed by the camera is split into four separate image components (15, 16, 17, 18) carried by four bundles of optical fibers (35, 36, 37, 38). Each bundle has a CCD (45, 46, 47, 48) and associated image processing circuitry (65, 66, 67, 68) which forms an electronic representation of the image component carried by that bundle.
Abstract:
In an electronic article surveillance system (24), quadrature transmitting and receiving antennas are used to improve field distribution. A transmitting antenna arrangement includes first and second adjacent co-planar antenna loops (42, 44) and excitation circuitry (46) for generating respective alternating currents in the first and second loops such that the respective alternating currents are 90 DEG out of phase. In a receiving arrangement (300), respective signals received from two adjacent co-planar antenna loops (302, 304) are respectively phase-shifted by +45 DEG and -45 DEG , and the resulting phase-shifted signals are summed. A far-field canceling transmitting antenna arrangement includes four loops (66', 78, 68, 70) operated at phases of 0 DEG , 90 DEG , 180 DEG and 270 DEG respectively. All four loops may be co-planar, with any bucking vertical segments being horizontally displaced from each other. Alternatively, the 0 DEG and 180 DEG loops may also be arranged in a common plane that is close to and parallel with another plane in which the 90 DEG and 270 DEG loops are arranged.