Abstract: A shielded, closely spaced transmit-receiver system for use in an electronic article surveillance system is disclosed wherein at least one of the antennas is provided with at least two twisted loops lying in a common plane each loop being twisted 180.degree. to be in phase opposition with the adjacent loop and wherein both antennas are substantially enclosed by a conductive shield having a discontinuity in an outer portion enclosing each of the twisted loops.

Abstract: A time-remaining gauge for use with video cassettes is provided, wherein the gauge includes a substrate having a pressure sensitive adhesive on one side and various indicia on the other side which may be aligned with the radius of tape on a supply or take-up spool on the cassette and viewed through a window in the cassette on which the gauge is affixed.

Abstract: A desensitizer apparatus for use with magnetically based electronic article surveillance systems having a marker containing at least one magnetizable section which when magnetized, alters the response of the marker produced by an alternating magnetic field provided in an interrogation zone. The apparatus includes a magnet assembly having an elongated permanent magnet section and a pair of elongated pole pieces which concentrate external fields produced by the magnet sections near a gap extending the length of the magnet section, the external field near the gap being sufficient in intensity to magnetize the magnetizable section of a marker positioned proximate thereto, and being rapidly attenuated a short distance from the gap. Accordingly, magnetically sensitive articles such as prerecorded magnetic recording cassettes to which the markers are affixed are not affected.

Abstract: A cover assembly for use with a disk-shaped optical recording medium, having two substantially identical halves, each having an inner surface adapted to provide upon assembly with the medium an air gap adjacent an optical recordable coating on the medium. Each cover half is transparent and has substantially no birefringent characteristics on the region overlying the air gap, thus allowing light to pass unimpeded therethrough. The cover assembly is adapted to be coupled to the central hub of the optical recording medium and to have a raised annulus adjacent thereto to support the assembly and minimize contact with the transparent portion.

Abstract: A thin film magnetic recording playback head is disclosed wherein mechanically coupled films of a magnetostrictive material and of a piezoresistive material are utilized with a solid state amplifier electrically coupled to sense resistance changes in the piezoresistive film. In operation, localized magnetic patterns on a recording medium induce strain in the magnetostrictive film, which in turn induces in the piezoresistive film corresponding changes in electrical resistance.

Abstract: A method of constructing an inductive-capacitive (LC) network is disclosed in which a predetermined pattern is cut from a metallic sheet to provide a multi-turn, essentially spiral-like configuration in which a plurality of interconnecting regions are left between adjacent turns. A pre-laminate is then formed by laminating one surface of the configured sheet to a surface of a sheet of dielectric material. A completed multi-turn inductor is formed by a second cutting operation in which the remaining interconnecting regions between the adjacent turns are removed. The LC network is completed by laminating a second metallic sheet to a dielectric layer overlying the completed multi-turn inductor. The first and second cutting operations and assembly of the respective sheets are performed such that any burrs resulting from the operations are directed away from the interlying sheet of dielectric material, thereby avoiding problems due to shorting out between the two metallic sheets.

Abstract: An optical recording medium containing a light-absorbing film of a refractary material selected from the group, consisting of boron, borides of carbon, silicon, hafnium, niobium, tantalum, titanium, tugsten, and zirconium, nitrides of boron, hafnium, tantalum and titanium, oxides of hafnium, cerium, magnesium and thorium, and silicides of niobium, tantalum, titanium, and tungsten less than 60 nm thick and which is sufficiently plastic to allow deformation upon localized heating by exposure to a focused laser beam, whereupon the localized heating of the light absorbing film enables information storage in the form of localized protuberances in the heated areas which can be used as a master for replication purposes.

Abstract: In a tape which is driven by an elastic pretensioned belt, discontinuities such as embossings in the surface of the belt promote the release of air from between the belt and the underlying tape, thus minimizing variations in tape tension and tape speed.

Abstract: A visual display device is featured which uses a new thermal addressing technique to provide a dark image upon a lighter background. The display is capable of being multiplexed to a large number of rows. The device comprises a cholesteric-smectic liquid crystal material mixed with a pleochroic dye of high order parameter. When the material experiences a transition from a higher to a lower, smectic thermal phase, two different textures or light states are developed; a transparent state and a light absorbing state. The transparent state is developed by applying a sensitizing voltage to certain portions of the medium. The pleochroic dye absorbs the light passing through the unsensitized portions of medium to provide the dark image. The row electrodes are made diffusely reflective so as to provide a double light pass through the medium to improve contrast.

Abstract: A reflector for use in liquid crystal displays is disclosed comprising a plate having a micro-lenticular surface over which are successive layers of reflective material, such as aluminum or silver and a light transparent material having a low index of refraction, i.e., an inex of refraction below that of SiO.sub.2, which is in optical contact with the reflective layer.The present invention also contemplates the method of fabricating such a reflective surface.

Abstract: A system is disclosed enabling bidirectional communications between a central station and a plurality of satellite stations over a switched data transmission network in which each satellite station initiates all communications between that satellite station and the central station such that priority data generated within a given satellite station is immediately transmitted to the central station, while routine data generated within each satellite station is stored for delayed transmission to the central station at different times previously set by the central station but monitored by local clocks within each of the satellite stations.

Abstract: An optical recording medium containing a light-absorbing film of amorphous carbon less than 60 nm thick and which is sufficiently plastic to allow plastic information upon localized heating is provided for exposure to a focused laser beam, whereupon localized heating of the light-absorbing film enables information storage in the form of localized protuberances in the heated areas which can subsequently be optically detected and can be used as a master information record for replication purposes.

Abstract: An automatic track following feature for use with a helical video recorder is disclosed which enables reproduction of video fields at normal speeds, fast and slow forward and reverse speeds, and at stop motion, wherein a mechanism for moving a playback head transverse to the helical tracks on a magnetic tape is provided in order to enable the head to remain centered on the track regardless of tape speeds and directions of movement. A head position control signal is generated for driving the head positioning mechanism based on a comparison of a signal based on the instantaneous tape speed with a reference speed indicating signal.

Abstract: A data cartridge recorder is disclosed in which a preformatted tape is employed to enable automatic detection of the beginning of the tape and the end of the tape as well as of the location of preidentifiable record locations positioned along a plurality of parallel tracks.

Abstract: A visual display device is featured which uses a new thermal addressing technique to provide a dark image upon a lighter background. The display is capable of being multiplexed to a large number of rows. The device comprises a cholesteric-smectic liquid crystal material mixed with a pleochroic dye of high order parameter. When the material experiences a transition from a higher to a lower, smectic thermal phase, two different textures or light states are developed; a transparent state and a light absorbing state. The transparent state is developed by applying a sensitizing voltage to certain portions of the medium. The pleochroic dye absorbs the light passing through the unsensitized portions of medium to provide the dark image. The row electrodes are made diffusely reflective so as to provide a double light pass through the medium to improve contrast.

Abstract: Large area, diffractive subtractive color filters are provided from a density image of a standing wave interference fringe field pattern in a high speed, high resolution silver halide photographic plate. The high speed enables conventional coherent sources to be spread out to provide a low but constant intensity over extended areas, while still enabling the production of the density image at exposure times sufficiently short to preclude vibrational degradation in resolution. The plates are then developed, overcoated with a photoresist and back-exposed, after which the photoresist is developed to provide a subtractive filter having an extended area surface relief pattern which includes a width controlled periodic diffraction grating.

Abstract: An automatic telephonic message transmission apparatus is disclosed which includes a base station and preferably a remote unit for receiving inputs indicative of various operator emergency conditions and for thereupon automatically sequentially dialing a plurality of preselected telephone numbers, and for thereupon transmitting aural messages indicative of the alarm condition. The apparatus includes solid state memories for storing a digital representation of aural messages, keyboard for inputting information such as selected telephone numbers, alarm times, etc., and a controller for acting on the input signals and keyboard entered data for controlling the automatic dialing operations.

Abstract: A system for contact duplication is disclosed wherein anhysteretic magnetization of a copy medium occurs using an anisotropic master medium wherein the two media are held in surface contact and an AC bias magnetic field is applied along the hard axis of the master media.

Abstract: A linear motor control system for a brushless DC motor is disclosed wherein a plurality of rotor position sensors are provided together with a means for selecting a first or second group of those sensors, thus enabling alternate sets of position signals to be selected depending upon motor speed. These respective sensor signals are then processed through a filter network to provide sinusoidal motor drive signals which continuously modulate motor winding currents to provide linear speed control, thereby resulting in an appreciable decrease in acoustical noise produced by the motor.

Abstract: An apparatus for editing digitally recorded audio signals in which entry and exit edit points are designated based on a display of data derived from audio signal data proximate to the edit points. The apparatus enables the automatic selected and combination of portions of audio signals on at least two channels to produce a composite audio signal digitally recorded on a record medium.