Abstract: A latch for use with a valve on the end of an exhaust vent typically associated with a clothes dryer or the like. The latch includes a flat, plastic bonded magnet having a layer of pressure sensitive adhesive (PSA) for bonding the magnet to one of either the hinged valve plate or stationary face plate of the valve while a strike plate formed of a conformable, magnetically susceptible material is bonded by a PSA layer to an opposing section of the other of the valve plate or face plate. The latch is kept closed by magnetic forces in the absence of blower expelled air, regardless of variations in pressure on the valve plate, such as may result from gusts of wind.

Abstract: An adjustable write-equalized recording circuit for recording data onto a magnetic tape. The circuit variably adjusts the amplitude of write-equalization pulses relative to the data waveform by an amount that can be either preset or determined during operation.

Abstract: A thin-film magnetoresistive playback head having films providing magnetic shielding and magnetic bias. At least one of the magnetic shield layers is also conductive so that the functions of shielding and biasing are combined. Preferably, both shield layers are conductive. A multiple element channel head is disclosed in which the magnetic/conductive layers extend in series from one transducer section to the next, allowing a single bias current to bias all of the sections.

Abstract: A thin-film magnetoresistive playback head having films providing magnetic shielding and magnetic bias. At least one of the magnetic shield layers is also conductive so that the functions of shielding and biasing are combined. Preferably, both shield layers are conductive. A multiple element channel head is disclosed in which the magnetic/conductive layers extend in series from one transducer section to the next, allowing a single bias current to bias all of the sections.

Abstract: A vehicle detector includes one or more inductive sensors connected to an oscillator circuit. A timing circuit defines a plurality of sequential measurement frame segments. The oscillator circuit is coupled to an inductive sensor during each of the measurement frame segments. The time duration of each of the plurality of measurement frame segments is measured. After the completion of each frame segment for a particular inductive sensor, a total measurement frame time duration for that sensor is calculated based upon durations of a predetermined number of measurement frame segments for that sensor. The total measurement frame time duration and a reference time duration are compared and a difference is determined. If the difference between the total measurement frame time duration and the reference time duration exceeds a threshold value, an output signal indicative of the presence of a vehicle in the vicinity of the inductive sensor is generated.

Abstract: A mechanism for accurately following the center of a track includes a voice coil, or a voice coil and stepper motor in combination. The voice coil and stepper motor combination operate to variably position a recording head transversely with respect to the width of the recording tape. The mechanism enables head positioning with very close tolerances due to the ability of the voice coil to finely position the head very accurately on the center of a track.

Abstract: A determination is made whether a minimum threshold period (or frequency) change has occurred in an oscillator signal indicating the initial presence of a vehicle over an inductive sensor. The change in period of the oscillator signal is measured over each of a plurality of frame segments. A magnitude of period change in the oscillator signal is recorded. If the number of frame segments that occur between detection of the threshold change in period and the magnitude change in period is less than a predetermined number, the detector does not make a speed measurement calculation. If the number of frame segments equals or exceeds the predetermined number, the time rate of change of the period of the oscillator signal is estimated. A vehicle detector calculates a sensor entry distance for a particular vehicle. A vehicle entry time is calculated by dividing the magnitude of period change by the rate of period change. Speed is then calculated by dividing the entry distance by the vehicle entry time.

Abstract: A security cartridge for magnetic tape recording media especially adapted for use with an electronic article surveillance system. The security cartridge includes a cartridge casing defining an internal, tape receiving chamber, a reel of magnetic tape windably carried within the chamber and a pair of orthogonally oriented magnetic markers carried within the internal chamber by a marker carrier bracket. The carrier bracket includes a pair of bracket leaves that present first and second generally orthogonally oriented, generally planar marker mounting surfaces, and engagement margins for operably, abutably engaging the internal structure of the cartridge chamber to position the carrier bracket within the chamber.

Abstract: A series resonant AC erase head drive circuit apparatus for use with a miniaturized cartridge-type tape drive includes apparatus for generating a non-overlapping pulse wave forms and for driving switches, power switches and a voltage controlled DC current source. The pulse form generating and power switch driving apparatus includes a clock frequency input coupled to an externally supplied clock frequency signal and an enable input coupled to an externally supplied enable signal, and includes a plurality of power switch driving outputs. The power switch driving outputs provide a plurality of power switch control signals which include a non-overlapping interval.

Abstract: A zero crossing detection circuit produces an output signal which changes state to indicate the occurrence of a positive-going zero crossing of an AC input signal. The circuit includes first and second input terminals, a current sensitive switch such as an opto-isolator, first and second current regulators, and a voltage limiter. The first current regulator is connected in series with the current sensitive switch, and the voltage limiter is connected in parallel with the first current regulator and the current sensitive switch. The second current regulator is connected between the first input terminal and the parallel combination of the voltage limiter and the first current regulator and the current sensitive switch. The first current regulator limits current through the current sensitive switch to a first current limit level, and the second current regulator limits current flowing between the first and second input terminals to a second current limit level which is greater than the first current level.

Abstract: This invention relates to a magnetic recording head assembly and method enabling an end user to record a unique servo control track on a magnetic recording tape while the tape is in the recorder to be used for recording and playback of computer data. Previously, most such control tracks were applied only at the time of manufacture of preformatted media. The invented head assembly includes, in addition to a plurality of sets of read/write transducers, a servo write head having an extended transverse width for uniformly recording a servo signal across the width of a servo track section, and a servo erase head having a plurality of alternating erasing and non-erasing sections adapted to controllably erase portions of the previously recorded servo signal, resulting in unique servo control tracks.

Abstract: The invention is related to a process of deactivating a magnetic security marker of an article surveillance system, wherein the security marker is detected by simulating conditions normally present in such a system, e.g., by creating between a transmitter and a receiver a sinewave electromagnetic field and the deactivating the security marker by means of the electronically switchable magnetizing apparatus in response to the detection of the magnetic field which corresponds to the magnetization of the security marker in the surveillance zone. It is the object of the invention to enable the magnetic security marker to be deactivated using any alternating power line. To this end, the magnetic system is automatically connected to a power line without circuit change when the security marker is detected.

Abstract: An optical traffic preemption detector detects pulses of light emitted by an approaching emergency vehicle and provides an output signal which is processed by a phase selector. The phase selector can request a traffic signal controller to preempt a normal traffic signal sequence to give priority to the emergency vehicle. A detector assembly is mounted in proximity to an intersection and can have multiple detector channels. A detector channel can have multiple photocells. A detector housing includes a base, at least one detector turret and a cap. A detector channel circuit includes a circuit board, a photocell with a lens placed over the photocell, and circuitry to produce an output signal.

Abstract: An optical traffic preemption detector detects pulses of light emitted by an approaching emergency vehicle and provides an output signal which is processed by a phase selector. The phase selector can request a traffic signal controller to preempt a normal traffic signal sequence to give priority to the emergency vehicle. A detector assembly is mounted in proximity to an intersection and can have multiple detector channels. A detector channel can have multiple photocells. Each photocell is provided with a rise time filter. If a detector channel has more than one photocell, the outputs of the respective rise time filters are coupled together. An output of a rise time filter, or coupled rise time filters, is first applied to a current-to-voltage converter and then a band pass filter. The band pass filter isolates a decaying sinusoid signal from a signal representative of a pulse of light.

Abstract: An optical signal emitter assembly emits light pulses which are received by an optical traffic preemption system detector. The optical signal emitter assembly employs a honeycomb element positioned in front of a light source which collimates light emitted by the optical signal emitter assembly. The optical signal emitter assembly is convertible from a stand-alone unit containing power supply circuitry, timing circuitry, and a light source in a single housing, to a unit wherein the light source can be mounted independently from a housing containing the power supply circuitry and the timing circuitry.

Abstract: A multiple magnet assembly for magnetizing a magnetizable element of a desensitizable electromagnetic article surveillance marker, in which each successive assembly provides at a working surface a magnetic field of the same polarity but decreasing intensity. Any demagnetization effect attributable to reverse or back fields associated with one assembly are overcome by magnetization produced by a subsequent assembly, thus allowing markers having magnetizable elements with significantly different coercivee forces to be magnetized by the same apparatus.

Abstract: A constant loop gain phase lock loop for recovering a clock from non-uniformly spaced data pulses utilizes a programmable current source and charge pump whereby the current into the charge pump is proportional to the number of VCO clock periods between data pulses. As the time between pulses increases the current charging the pump increases and when the time between pulses decreases the current charging the pump decreases to maintain a constant loop gain independent of the data pattern.

Abstract: A theater rope connector for terminating a fine fiber rope such as typically used in patron control. The connector comprises two injection molded plastic components, the first being formed to have a hook or other structure for attaching the connector to a suitable fixture and toothed legs for penetrating and thus securing the rope. The other component comprises a sleeve adopted to fit over the first component and thereupon press the toothed legs into the rope, securing them in place. The sleeve also has a flange at one end adapted to mate with a peripheral recess on the first component, thereby maintaining the two components in position.

Abstract: A method of optically transmitting data from an optical emitter to a detector mounted along a traffic route is used in an optical traffic preemption system. The method allows variable data to be transmitted in a stream of light pulses by interleaving data pulses between priority pulses. By allowing data to be transmitted in a stream of light pulses, an optical emitter constructed in accordance with the present invention transmits an optical signal that can include an identification code that uniquely identifies the emitter, an offset code that causes a phase selector to create a traffic signal offset, an operation code that causes traffic signal lights to assume at least one phase and a range setting code that causes a phase selector to set a threshold to which future optical transmissions will be compared. Phase selectors constructed in accordance with the present invention are provided with a discrimination algorithm which is able to track a plurality of optical transmissions with each detector channel.