Abstract: A process for producing a thin-film magnetic tape head includes the steps of coating a substrate with a layer of material which protects the substrate from an etchant. A cavity is etched into the substrate and a prismoid of magnet material is deposited in the cavity. The sides of the substrate are removed so that the prismoid projects above the sides for a substantial portion of the height of the prismoid. The substrate is coated with a gap-coating layer and the gap-coating is removed from one side of the prismoid. Another layer of magnetic material is deposited onto the substrate and various parts, such as pole shoes, are formed. The substrate is polished and the apex of the prismoid is removed. Head windings are made. A return path for the head windings is provided by depositing another layer of magnetic material onto the substrate. A protective layer of a metal oxide is deposited onto the substrate.

Abstract: An improved cooling device for cooling the magnetic head (M) of a magneto-optical disc player includes a plurality of arcuate ribs (R) formed as portions of concentric circles and having centers coincident with the axis of rotation of the disc player. The reading/recording head (M) is arranged between the ribs. The rotation of the disc in the proximity of the cooling device creates airflow between the ribs and serves to cool the magnetic head.

Abstract: A circuit for generating a cut-off voltage for the switching diodes in a high frequency filter by rectifying the output signal of an oscillator includes a first diode which has a low threshold voltage and which rectifies the output signal to apply the cut-off voltage to the switching diodes in a first mode of operation. A second diode, having a low resistance, is parallel to the first diode and by-passes the first diode in a second mode of operation.

Abstract: A method of adjusting the moveable unit of a positioning device having a light source and a photodetector for scanning markers identifying positions at which the moveable unit is to be located includes the steps of accurately and manually positioning the unit at one of the identifying positions. The unit is then automatically driven to a second position where the output signal of the photodetector is maximum. The deviation from the first position to the second position is stored as an offset which is subsequently used to accurately position the moveable unit.

Abstract: An optical scanning system for a compact disc having a sinusoidal data track radially meandering, at a selected frequency, about the axis of rotation of the disc includes a first laser beam for reading data from the data track. A +1 level laser beam and a -1 level laser beam respectively track the opposite edges of the data track and generate a tracking error signal. The +1 level laser beam and the -1 level laser beam are separated, with respect to the disc, by a distance equal to an odd integer multiple of one half the wavelength corresponding to the selected frequency. The +1 and -1 laser beams are not modulated by the sinusoidal data track and standard tracking circuitry can be used to track the data track.

Abstract: A system for regulating the transfer impedance of a plurality of current-to-voltage converters to a substantially equal value includes a reference voltage source and a reference impedance for providing a reference current. A reference current-to-voltage converter is responsive to the reference current and provides an output voltage. A comparator is responsive to the reference voltage and the output voltage and provides a control signal to the reference current-to-voltage converter and to all the other current-to-voltage converters to maintain the transfer impedance of all the current-to-voltage converters constant.

Abstract: An improved cathode ray tube has a shrink-fit implosion protection band surrounding a portion of the tube envelope. The band includes a plurality of lugs for supporting the tube. The improvement comprises the band including a plurality of embossments arranged around the band. The embossments extend outwardly from the tube for a preselected distance to form cavities between the tube envelope and the embossments. The embossments include smooth outer surfaces to which the lugs are attached by welds. The embossments have indentations at the locations of the welds that extend into the cavities. The cavities have depths greater than the depths of penetration of the indentations into the cavities. By utilizing the embossments, the indentations, caused by welding, remain out of contact with the tube envelope.

Abstract: A holding device for holding a record (CD) in a magneto-optical recording/playback device includes a first wheel (R1) pressing against one side of the record. A first pivotable arm (AR1) supports a second wheel (R2), motion of the first arm moves the second wheel against the other side of the record and also centers the record in the holding device. A second pivotable arm (AR2) supports a magnet (M). A lever includes a third pivotable arm (AR3) mounted on an axis (A3) supported by the first pivotable arm and is in contact with the second arm. A fourth pivotable (AR4) arm pivots in a direction opposite from that of the third pivotable arm. A stop (AS) is in the proximity of the fourth pivotable arm. Accordingly, motion of the first arm (AR1) away from the record causes the third arm (AR3) to force the second arm (AR2) away from the record and also causes the fourth arm (AR4) to hit the stop (AS) and cause the third arm to move the second arm further and the magnetic head (M) away from the record.

Abstract: A display device having a plurality of select lines includes redundant select line scanners. Each scanner includes a plurality of substantially identical stages having an input terminal and an output terminal. The stages and select lines are ordinally numbered and correspondingly numbered stages are connected to opposite ends of the correspondingly numbered select lines by separate line segments. The stages within each scanner are cascaded by connecting the output terminal of each stage to the input terminal of the immediately succeeding stage. The select line scanners are independently operable by the provision separate power supplies and clock generators. During testing, one scanner is made to look like a high impedance to the scanner being tested. Failed stages of a scanner are replaced by the correspondingly numbered stage of the other scanner simply by opening the separate line segment of the failed stage.

Abstract: A select line scanner for a liquid crystal display includes a plurality of cascaded stages each having an input terminal and an output terminal. Each stage includes an output circuit which switches the output terminal between high and low states. A first node switches the output terminal in response to an input signal and a second node keeps the output terminal low between the input pulse and a clocking pulse.

Abstract: A mount for mounting a lens in an optical scanning device includes a tubular portion having a first surface which rotatably supports the lens. A second surface includes a plurality of arcuate supports. An annular spring is supported by the arcuate supports and is bent at the points of contact with the supports to extend outwardly beyond the supports to bias the mount and the lens against the scanning device in which it is mounted.

Abstract: A protection circuit for a solid state instrument includes a plurality of fuses and a switching device arranged in parallel with the input capacitance of the solid state instrument, The fuses protect the instrument from high voltage surges, and the switching device protects the instrument from lower voltage surges. The fuses and the switching device are solid state devices and thus can be fabricated along with the solid state instrument.

Abstract: A demultiplexer includes a plurality of transistors having conduction paths connected between an input terminal and output nodes. The control electrode of every transistor is connected to one line of a most significant bit bus by a first capacitive device, the control electrode of every transistor is also coupled to one line of a least significant bit bus by a second capacitive device. When the capacitive devices associated with the same transistor simultaneously receive an enable signal the transistor is turned on and current flows from the input terminal to an output node. Each transistor within the demultiplexer thus acts as a three state gate.

Abstract: A system for applying brightness signals to the pixels of a display device includes a transmission gate for each column of pixels. The control electrodes of the transmission gates are precharged to the threshold voltage of the gates to substantially increase the speed of the system. Comparators compare brightness voltages to a reference ramp voltage to enhance the speed and accuracy of the system.

Abstract: A shift register includes transistors having conduction paths serially connected at a node and between an input terminal receiving a constant voltage and a clocked terminal receiving a clocked voltage of a first phase. The control electrode of one of the transistors receives a clocked voltage of a second phase and the control electrode of the other transistor receives an input signal. An inverter is arranged between the node and the output terminal.

Abstract: A pulse logic circuit comprises a plurality of interconnected stages. Each of the stages includes a relatively large node-charging transistor which, when enabled, forwards charging current to a node from a timing pulse of one of a plurality of phases applied to a load capacitance in series with the node-charging transistor. Such large transistors exhibit significant gate-to-source and gate-to drain distributed capacitances. The response time for charging a selected stage node can be decreased by precharging the gate of the node-charging transistor of a selected stage to enable the transistor prior to the application of a timing pulse, thereby increasing the maximum operating speed of the circuit. Disclosed species of such a pulse logic circuit include time vernier circuits which can be utilized as control circuitry for a liquid crystal television or computer display.

Abstract: A tensioned shadow mask/frame assembly includes horizontal top and bottom members and vertical side members. One of the horizontal members is permanently affixed to the side members and the other horizontal member is slideably supported on the side members. The horizontal members are biased apart to put tension on a shadow mask which is stretched across and permanently affixed thereto. The cross sectional configuration of the horizontal members is an acute angle having a long side and a short side joined at a rounded apex to maximize the stiffness of the members.

Abstract: A circuit for testing a liquid crystal display for open data lines, for identifying select lines shorted to data lines, and for identifying failed data line scanner stages includes thin film transistors arranged between each data line and a segmented bus. A sectioned shift register sequentially actuates the thin film transistors and the bus segments are monitored while data signals are applied to the data lines. The absence of a voltage on the bus indicates an open data line. The bus is also monitored while select signals are applied to the select lines and the shift register sequentially actuates the thin film transistors, the presence of a voltage on the bus indicates a short between a data line and a select line.

Abstract: A select line scanner circuit for a display device has a plurality of register stages. The register stages each include first and second register segments and first and second latch circuit means which receive select signals and apply oppositely poled logic signals to the output nodes of the register stages. Voltage boosting means are associated with at lest one of the register stages to assure that the logic signals are applied at the proper levels.

Abstract: An internal magnetic shield for a color picture tube has lower reluctance in the sides of the shield than the top and bottom of the shield.