Abstract: An optical switch comprising a substrate with a refractive index n.sub.1 which is transparent with respect to a guided light beam, an optical waveguide film with a refractive index n.sub.2 which is formed on the substrate, a low-refractive-index region with a refractive index n.sub.2 ' which is smaller by a predetermined value than the refractive index n.sub.2 formed at a predetermined location in the optical waveguide film, a movable dielectric chip with a refractive index n.sub.4 which is transparent with respect to the guided light beam and a relative distance of which is adjustable relative to a plane including the low-refractive-index region and a vicinal area of the optical waveguide film in the vicinity of the region, and an intermediate layer with a refractive index n.sub.3 disposed between the plane and the movable dielectric chip wherein the refractive indices n.sub.1, n.sub.2, n.sub.2 ', n.sub.3 and n.sub.4 have a relationship of n.sub.2 >n.sub.2 '>n.sub.4 >(n.sub.1, n.sub.

Abstract: A switched capacitor filter having at its input, a signal converter for creating so-called 100% sample and hold signals. The signal converter comprises a plurality of switched capacitors. The switched capacitors, connected in parallel with each other, receive the same successive input signals and supply the so-called 100% sample and hold input signals to the switched-capacitor filter. The switched capacitors, on one hand, charge each of said input signals sequentially and, on the other hand, alternately discharge the respective stored input signals one by one.

Abstract: A circuit for detecting a closed loop formed by actuation of a telephone set, the loop being indicative of a connection between the telephone set and an exchange through a ring line and a tip line. The detecting circuit comprises generators for generating first and second detection signals having amplitudes proportional to a ring line current and a tip line current respectively, a summing circuit for summing the detection signals and a comparator for comparing the outputs of the summing circuit and a reference value and delivering an output depending upon the result of comparison.

Abstract: In a process for preparing optical fibers, an optical fiber preform is heated and softened to be drawn at a high speed into an optical fiber. The optical fiber is passed through a plastic pipe of a thermoplastic resin. As the optical fiber is passed through the plastic pipe, the lower part of the plastic pipe is gradually inserted into a heating unit to be uniformly heated. The heated plastic pipe is softened and is coated over the optical fiber.

Abstract: First and second optical fiber groups, each composed of optical fibers in layers, are held by alignment mating means, with the optical fibers placed at predetermined positions and end faces of corresponding pairs of them butted with each other. A light beam emitted from a CO.sub.2 laser is focused by a focusing optical system on the joints of the butted optical fibers. When the light beam is focused on one pair of butted optical fibers to fusion-splice them, the diameter of the focused light beam reaching the optical fibers adjacent to the irradiated ones is large so that their heating temperature by the focused light beam may not exceed their melting point. The focusing optical system and the alignment mating means are moved relative to each other to fusion-splice the butted optical fibers in succession.

Abstract: This PARCOR-type speech synthesizer replaces a ten-stage lattice type filter with a pipeline multiplier and feedback loop, and provides a loss circuit (for bandwidth broadening) using subtraction circuits for multiplication.

Abstract: A printer head for mosaic printing having a plurality of needles positioned on a straight line each being selectively driven towards a paper through an ink ribbon has been found. The printer head comprises of a cylindrical permanent magnet, a first yoke covering the bottom of the permanent magnet, a plurality of electromagnets each positioned on a circle on the first yoke with the predetermined angle intervals, a disk shaped spring having an outer ring and a plurality of projections towards the center of the disk, a plurality of armatures each attached to the related projection of the disk spring, a plurality of print needles each attached to the related projection of the disk spring so that each of the needles has the perpendicular component to the disk spring plane.

Abstract: A multi-frequency signal receiver, in which the digital input signals having the sampling frequency of 8 KHz or a multiple thereof are resampled at a sampling frequency of 4 KHz by means of a resampling circuit and in which the signals thus resampled are subjected to the band selection by means of a digital filter so that the frequency of the input signals may be identified.

Abstract: A key telephone system comprises a main equipment connected to at least one set of central office (CO) lines and capable of connecting thereto a plurality of key telephones. The main equipment includes a dual tone multifrequency (DTMF) sending circuit common to the key telephones, and the respective key telephones are connected to the main equipment through six wiring cables forming a pair of two-way voice frequency talking circuits and one two-way data transmitting circuit. A plurality of switching matrixes are included in the main equipment for selectively connecting the CO lines and the talking circuits, and also connecting the data transmitting circuit through the DTMF sending circuit to the CO lines and one of the talking circuits in the key telephone, whereby respective functions of hand-free talk-back and off-hook signalling during intercom talking, and speaker monitoring function during CO line talking are performable.

Abstract: A code converting circuit of simple construction composed of an exclusive OR circuit and a flip-flop circuit is provided on each of transmitting and receiving sides of a digital data transmission system according to a differential phase shift keying system, to convert two consecutive errors on adjacent bits peculiar to the differential phase shift keying system into only an error on a single bit. As a result, it is not required to employ a code having an excellent error-correcting capacity in the digital data transmission system, and thus a high transmission efficiency is attained by the use of a code which is relatively deficient in error correcting capacity.

Abstract: A method of fabricating a single-mode optical fiber preform wherein a core torch produces fine glass particles eccentrically with respect to the center area of a flame stream, the core torch being so arranged as to blow the flame stream at an angle inclined to a seed rod. The porous glass body forming the core is grown on one end of the rod and in the direction of the axis of the rod. A cladding layer is formed on the periphery of the porous glass core body by at least one torch for forming the cladding. The obtained porous glass body is heated and vitrified into a transparent glass body, which is sealed in a silica tube for jacketting to form a single-mode optical fiber preform. At least one exhaust port is disposed within a distance of 1 mm to 50 mm from the periphery of the porous glass body and in the vicinity of the growing surface of the glass body to exhaust residual glass fine particles and undesired gases. A porous glass body having a diameter of 20 mm or less is easily formed.

Abstract: A battery embodying this invention comprises an anode including an anode-active material formed of one metal selected from the Group Ia metals or preferably lithium metal, a cathode including a cathode-active material formed of organic compounds having a .pi.-electron conjugated system, and an electrolyte prepared from a material which is chemically stable to the cathode and anode materials and permits the migration of the ion of the anode metal to the cathode for electrochemical reaction with the cathode-active material.

Abstract: Glass material for infrared ray-transmitting optical fibers comprises a three-component material made of a 28 mol % to 38 mol % BaF.sub.2 -2 mol % to 7 mol % GdF.sub.3 -58 mol % to 69 mol % ZrF.sub.4 -based composition. The glass material is cast in a metal mold with a hollow section which is preheated to a temperature of at least 100.degree. C. but below the glass deformation temperature and annealing the melt in the metal mold to form a glass rod. The glass rod forming step includes heating the melt in the temperature range of between about 200.degree. C. and less than the glass deformation temperature and cooling the melt. The glass rod is removed from the metal mold and optically polished at the ends and sides and is then drawn into a fiber while applying tension to the tip of the glass rod while the glass rod is being heated. The glass rod is drawn into a glass fiber while maintaining the temperature at the end portion of the glass rod constant.

Abstract: A time division switching circuit with time slot interchange uses an input shift register to convert one-frame binary coded input data of time division multiplex type from an incoming line into a parallel bit output. The parallel bit output undergoes gate control of a gate matrix and its bit array is statically changed to a given bit array. The on/off control of the gate at the cross point of the gate matrix is conducted according to parallel bit outputs of a plurality of control shift registers which stores predetermined contents. The one-frame bit data thus exchanged are supplied to an output shift register. They are transmitted to an outgoing line as binary coded output data of time division multiplex type.

Abstract: A D/A conversion system with a compensation circuit comprises a D/A converter for converting a digital input signal into an analog signal and a memory for storing a compensation data used for the compensation of the output of the D/A converter at an address corresponding to the digital input signal. The digital input signal is applied to the D/A converter and a signal corresponding to the digital input signal is applied to the memory. The output of the D/A converter is adjusted on the basis of the compensation data read out from the memory.

Abstract: A clock recovery circuit includes an oscillator having a frequency which is substantially equal to the clock frequency of bursts which are transmitted from a plurality of stations. A phase difference detector circuit responds to phase differences between clock signals extracted from each of the bursts and from the output from the oscillator. An averaging circuit averages the detected phase differences over an interval which is designated by a first control signal. A memory circuit stores the averaged phase difference in response to a second control signal and reads out the stored phase differences in response to a third control signal. A control circuit generates the first to third control signals in response to the output from the oscillator. A phase shift circuit shifts the phase of the output from the oscillator, based on the phase difference read out from the memory circuit. This generates and recovers the original clock pulse signal.

Abstract: A process for producing a preform for glass fiber for optical transmission by heating supply gases to form fine particles that are deposited on a rotating starter member to form an aggregate of fine glass particles which are then sintered to give a transparent vitreous material, characterized by a first heating stage wherein the aggregate of fine glass particles is sintered by increasing the temperature at a constant rate in a gaseous atmosphere which contains a halogen or halide and which has dehydrating activity, followed by holding the aggregate for a given period of time at a temperature in the range that causes considerable shrinkage of the aggregate, and a second heating stage where said aggregate is heated to the vitrifying temperature.

Abstract: Copper-nickel-tin alloys having high tensile strength and conductivity suitable for lead conductor materials for integrated circuits are produced by melting a starting material containing 0.5-3.0% by weight of Ni, 0.3-0.9% by weight of Sn, 0.01-0.2% by weight of phosphorus and 0-0.35% by weight of at least one of Mn and Si other than Cu, casting the molten metal, rolling conventionally the cast into a sheet having a thickness corresponding to more than 60% of cold reduction rate of the final necessary gauge, annealing such a rolled sheet at a temperature of 300-395.degree. C. for 1 hour, cold rolling the annealed sheet and annealing the cold rolled sheet at a temperature of 150-250.degree. C. for 1 hour.

Abstract: A method for producing a multi-component glass fiber preform which comprises the steps of nebulizing an aqueous solution of at least one metal salt, and reacting the nebulized solution and a gaseous glass raw material with oxygen gas at a high temperature to produce particulate glass material deposited on a substrate. Apparatus for producing such a preform is also disclosed.

Abstract: A switched-capacitor filter provided with, at its input stage, a prefilter comprised only of a plurality of additional switched capacitors together with a switched capacitor common to the switched-capacitor filter. The switched capacitor common to the switched-capacitor filter is driven by primary clock pulses having a period T, while the additional switched capacitors are sequentially driven by secondary clock pulse groups. Each of the secondary clock pulse groups has the same period T, and the phases of the second clock pulse groups are shifted by T/2.sup.k, 2T/2.sup.k, 3T/2.sup.k . . . (2.sup.k -1)T/2.sup.k with respect to the first clock pulses (k is a positive integer). The sampled and held signals in the switched capacitors are supplied synchronously to the switched-capacitor filter.