Abstract: An optical guide switching assembly in which steering devices are used to assembly deflect radiation from a transmitting guide to a selected receiving guide. Each of the steering devices includes a collimator light emerging from the transmitting guide and an actuator to cause relative movement between the collimator and the guide to cause the deflection, or to move the guide and collimator together. The actuator can be piezoelectric and of either a foil type, or a monolithic type, and mechanical leverage can be used to improve deflection. Capacitive sensing means provide positional information for feedback control, preferably in a diagonal switching arrangement.

Abstract: A uni-directional tag for use with position and orientation detection systems, which is not affected by exposure to high magnetic field levels. The tag is constructed from special geometry of magnetic materials and is applicable for example to catheter location systems.

Abstract: A fiscal electricity meter is described for measuring the energy supplied to a load. The load current flows through the primary winding of a transformer and induces an EMF indicative of the current flowing in the secondary winding. The secondary winding comprises a sense coil, arranged to couple more strongly to the primary, and a cancellation coil which have equal and opposite turns area products so as to provide a null response to extraneous magnetic fields. The coils are arranged so that their magnetic axis are co-located and aligned together so that they also provide a null response to extraneous magnetic fields having a field gradient.

Abstract: Magnetic tags or markers are disclosed, together with a variety of techniques by means of which such tags may be interrogated. In one aspect, the magnetic marker or tag which is characterised by carrying a plurality of discrete magnetically active regions in a linear array. In another aspect, the invention provides a method of interrogating a magnetic tag or marker within a predetermined interrogation zone, the tag comprising a high permeability magnetic material, for example to read data stored magnetically in the tag or to use the response of the tag to detect its presence and/or to determine its position within the interrogation zone, characterized in that the interrogation process includes the step of subjecting the tag sequentially to: (1) a magnetic field sufficient in field strength to saturate the high permeability magnetic material, and (2) a magnetic null as herein defined.

Abstract: A magnetic tag or marker is described which is capable of functioning as a multi-bit information carrying tag. The tag may be attached to an article and then used as a means of identifying that article, generally as it enters or is positioned within an interrogation zone. The tag comprises (a) a first magnetic material characterized by high permeability, low coercivity and a non-linear B-H characteristic; and (b) a second magnetic material which is capable of being permanently magnetized, the second magnetic material being magnetized with a non-uniform field pattern (A, B, C). Detection systems for use with such tags, and write/read system using them, are also disclosed.

Abstract: A reader for interrogating a magnetic tag, e.g. for reading data stored in the tag, is described. The reader comprises a field generating device the magnetic field produced by which defines an interrogation zone, wherein said field generating device comprises: (a) means for generating a magnetic field: (b) a transmit coil for transmitting an interrogating electromagnetic signal into the interrogation zone so as to interact with a magnetic tag, when present in said interrogation zone; and (c) at least one receive coil for receiving an electromagnetic signal generated by a tag in response to said interrogating signal and the magnetic field produced by said magnetic field generating means. The field generating means can take the form of a pair of hollow cylinders, giving rise to a “loop” reader, or it can be a flat magnet, giving rise to a “side pass” reader.

Abstract: An electrical current sensor and utility electricity meter, the current sensor comprising a &pgr; resistor shunt configuration, wherein the resistors comprise layered conductors at substantially equal temperatures to provide a zero temperature coefficient sensor. A fiscal electricity meter is described together with a four-layered current sensor fabricated using PCB techniques.

Abstract: Magnetic tags or markers are disclosed, together with a variety of techniques by means of which such tags may be interrogated. In one aspect, the magnetic marker or tag which is characterised by carrying a plurality of discrete magnetically active regions in a linear array. In another aspect, the invention provides a method of interrogating a magnetic tag or marker within a predetermined interrogation zone, the tag compromising a high permeability magnetic material, for example to read data stored magnetically in the tag or to use the response of the tag to detect its presence and/or to determine its position within the interrogation zone, characterized in that the interrogation process includes the step of subjecting the tag sequentially to: (1) a magnetic field sufficient in field strength to saturate the high permeability magnetic material, and (2) a magnetic null as herein defined.

Abstract: Magnetic tags or markers are disclosed, together with a variety of techniques by means of which such tags may be interrogated. In one aspect, the magnetic marker or tag which is characterized by carrying a plurality of discrete magnetically active regions in a linear array. In another aspect, the invention provides a method of interrogating a magnetic tag or marker within a predetermined interrogation zone, the tag comprising a high permeability magnetic material, for example to read data stored of the tag to detect its presence and/or to determine its position within the interrogation zone, characterized in that the interrogation process includes the step of subjecting the tag sequentially to: (1) a magnetic field sufficient in field strength to saturate the high permeability magnetic material, and (2) a magnetic null as herein defined.

Abstract: Magnetic tags or markers are disclosed, together with a variety of techniques by means of which such tags may be interrogated. In one aspect, the magnetic marker or tag which is characterized by carrying a plurality of discrete magnetically active regions in a linear array. In another aspect, the invention provides a method of interrogating a magnetic tag or marker within a predetermined interrogation zone, the tag comprising a high permeability magnetic material, for example to read data stored magnetically in the tag or to use the response of the tag to detect its presence and/or to determine its position within the interrogation zone, characterized in that the interrogation process includes the step of subjecting the tag sequentially to: (1) a magnetic field sufficient in field strength to saturate the high permeability magnetic material, and (2) a magnetic mill as herein defined.

Abstract: A detector for sensing the presence of a magnetic tag having an axis of easy magnetization, which comprises (1) either (i) a magnet or (ii) a pair of magnets arranged in magnetic opposition, the magnet or magnets being disposed so as to define a spatial region through or across which the magnetic tag is, in use, passed, the disposition of the magnet(s) and the resultant magnetic field pattern being such as to cause a change in polarity of the magnetization of the magnetic tag in the course of its passage through a magnetic null within the spatial region; and (2) a receiver coil or coils positioned above and in proximity to one pole of the magnet (where a single magnet is employed), or positioned between the pair of magnets (where two magnets are employed) and arranged to detect magnetic dipole radiation emitted by a magnetic tag as it passes through the magnetic null with the easy axis of magnetization of the tag oriented in the direction of travel.

Abstract: Magnetic tags or markers are disclosed, together with a variety of techniques by means of which such tags may be interrogated. In one aspect, the magnetic marker or tag which is characterized by carrying a plurality of discrete magnetically active regions in a linear array. In another aspect, the invention provides a method of interrogating a magnetic tag or marker within a predetermined interrogation zone, the tag comprising a high permeability magnetic material, for example to read data stored magnetically in the tag or to use the response of the tag to detect its presence and/or to determine its position within the interrogation zone, characterized in that the interrogation process includes the step of subjecting the tag sequentially to: (1) a magnetic field sufficient in field strength to sacurate the high permeability magnetic material, and (2) a magnetic null as herein defined.

Abstract: A surgical device, e.g. a catheter or a prosthesis, is disclosed which is characterised in that it carries, at a predetermined location, a tag formed of a high permeability, low coercivity magnetic material. Also disclosed is a method of locating a surgical device within the human or animal body, which comprises inserting the device into the body together with a magnetically active marker, the marker being associated with a predetermined location on the surgical device; and sensing the position of the marker, and hence of the surgical device, by remotely detecting its magnetic response to an interrogating signal. Systems for use in this method are also disclosed.

Abstract: An improved EAS tag is disclosed. The tag is characterised in that the or one of the magnetic materials on the tag is divided into distinct zones such that the zones and their relative positions can represent information or a code which is readable magnetically by passing the tag through a magnetic field which comprises a relatively small region of zero magnetic field (a magnetic null) contiguous with regions where the magnetic field is sufficient to saturate said magnetic material, the tag being moved through the magnetic field and its magnetic response being detected as it traverses the magnetic null.

Abstract: An apparatus for indicating the angular position of a rotatable member includes a drive coil with its axis corresponding to the axis of rotation of the rotatable member. A coil is wound around the rotatable member, and a capacitor is provided in the coil to form an LC resonant circuit. The coil on the rotatable member is wound so that application of an alternating magnetic field to the drive coil induces a resonance in the LC circuit which is constant for all angular positions of the rotatable member. Pick-up coils are provided such that the planes of these coils and the drive coil are orthogonal. The resonance of the LC circuit produces signals in the output coils which depend upon the angular position of the rotatable member. The signals may be processed to determine that angular position, and the processing is simplified with this arrangement of output coils since the signals produced therein are quadrature signals.