Showing papers by "NEC published in 1970"

Optical characteristics of a light-focusing fiber guide and its applications

Abstract: A lenslike glass fiber guide with a parabolic variation of refractive index has been developed. This optical guide named SELFOC® has the following characteristics: simultaneous transmission of laser beams modulated by wide-band signals through narrow space; optical image transmission; realization of a lens with tiny aperture or with extremely short focal length; and the possibility of being bent with a small radius of curvature without spoiling transmission characteristics. In the case of a typical fiber guide with length 1 meter and diameter 0.3 mm, transmission loss is about 0.2 dB and depolarization is about 20 dB at wavelength 0.63μ. The mode pattern of a laser beam after passing through the fiber guide is scarcely deformed. The fiber guide can be used as a transmission line or lens, in optical communication, optical data processing, and optical instruments.

Electric-Field-Induced Color Changes and Pitch DILATION in Cholesteric Liquid Crystals

Abstract: A new electric-field-induced color range, in which colors change from blue to red with increasing field, has been observed in cholesteric liquid crystals. Observations of this new color range quantitatively confirm the theories of Meyer and de Gennes and enable identification of the specific nature of the electric-field-induced cholesteric-nematic phase transitions previously observed by other workers.

Field effect semiconductor device with memory function

Abstract: A field effect transistor is provided with a gate assembly comprising a sandwich of a layer of silicon oxide with excess silicon between two insulating films of appropriate thickness for the entrapment of charge carriers in the silicon-rich silicon oxide layer. Such entrapment provides the transistor with information storage capabilities in which information can be stored for a long time and readily erased or modified.

Memory matrix using mis semiconductor element

Abstract: A memory matrix device is disclosed in which an MIS semiconductor element is employed as the memory element. The semiconductor element has an insulating film disposed between the semiconductor substrate and conductor electrode. That film contains capture centers which capture electrons upon the application of a voltage exceeding a critical value across the electrode and substrate.

Failure analysis of evaporated metal interconnections at contact windows

Abstract: An analysis of the open metallization problem at oxide steps at the surface of planar devices is described. This failure mechanism is essentially based upon the presence of a film discontinuity which grows during the evaporation process at the interface of coarse and dense crystal structures of the evaporated film. The growth rate of the coarse surface is somewhat larger than that of the normal surface. This mismatch in growth rates gives rise to the film discontinuity due to the self-shadowing effect by the former surface. The film discontinuity is apt to occur at the sharp step of phosphosilicate glass because of the following two reasons: 1) a large vapor-incidence angle to the perpendicular side wall; 2) a spontaneous growth of the coarse surface at the sharp edge of the step. Techniques investigated to improve the interconnection reliability include : 1) evaporation at elevated substrate temperature (∼300°C), 2) reduction of the thickness of phosphosilicate glass, 3)perpendicular vapor incidence to the substrate, and 4) protection of the discontinuity against corrosive agents.

The current pulse ratings of thyristors

Abstract: This paper describes how the current pulse ratings of thyristors during turn-on spreading can be obtained from the maximum allowable junction temperature based on time-to-failure using a combination of analytical and experimental methods. The instantaneous junction temperature rise of a thyristor is analyzed with the aid of a digital computer. In the calculation of temperature rise, the transient thermal impedance during turn-on spreading is considered. Analyzed results agree with the values obtained directly by an infrared detector. In order to estimate the maximum allowable junction temperature based on time-to-failure, "step-stress capability tests" were conducted. In many cases, it was found that there were modes of both catastrophic and degradation failure. The maximum allowable junction temperature was estimated for the nonrepetitive and repetitive current pulse ratings.

Multiplex communication system for transmitting television and facsimile signals

Abstract: A multiplex communications system is described in which a continuous signal having a relatively narrow frequency band such as a facsimile signal, may be superimposed on a signal having periodic idle intervals such as a television signal.

Paired signal transmission system utilizing quadrature modulation

Abstract: Signal transmission systems for the transmission of a pair of information signals are provided in accordance with the teachings of the present invention wherein a pair of carrier signals in quadrature phase relation are amplitude modulated, respectively, by the pair of information signals. One of the carrier signals, a double sideband signal obtained from amplitude modulating such one carrier signal with one of the pair of information signals and a double sideband signal obtained by amplitude modulating the other of the carrier signals with the other of the information signals which has had the low frequency components removed therefrom are transmitted as quadrature modulation signals to at least one receiving station over a predetermined transmission path. At the receiving station, one of the carrier signals is regenerated from the quadrature modulation signals received thereby and such regenerated carrier signal is relied upon to accomplish the demodulation of the quadrature modulation signals received.

Microwave bandpass filter with higher harmonics rejection function

Abstract: A rectangular waveguide bandpass filter for transmitting fundamental electromagnetic waves f 0 in a fundamental mode TE101 and attenuating second harmonic waves 2f 0 therein, comprising two susceptance elements spaced apart a distance of one-third waveguide wavelength in a lengthwise direction interiorly of the waveguide to form a resonant cavity for passing a frequency band including the fundamental wave f 101, attenuating the second harmonic wave 2f 101, and preventing resonant frequencies of modes higher than the fundamental mode TE101 from decreasing into a frequency region below the second harmonic; and one or two adjustable screws disposed between the two susceptance elements in one or both waveguide wide walls to project into the interior of the cavity at a position which is one-twelth of the one-third waveguide wavelength susceptance element spacing and which is from an adjacent narrow waveguide wall one-third of the overall distance between the two narrow waveguide walls whereby the screws are restricted to function as one or two capacitive elements only for the TE101 mode.

Electronic memory circuit employing semiconductor memory elements and a method for writing to the memory element

Abstract: Data is written into a memory storage device by applying a negative voltage to the gate electrode of an MIS-type transistor, and a positive voltage to at least one of the drain and source of that transistor. The voltage difference between the gate and the source or drain exceeds a critical voltage so that electrons are injected and trapped in the gate film. Also disclosed is a memory matrix in which a plurality of MIS transistors are arranged in a matrix array and have their gate and source-drain electrodes connected to row-and-column drive lines.

Digital signal reception system

Abstract: A digital system reception signal comprises an error detection circuit for detecting an error code contained in the transmitted coded signal. Upon the detection of the error code, the received composite digital signal of the repetition period or scanning line replaces the stored coded signal of the previous repetition period.

Frame synchronizing circuit for high clock frequency digital communication

Abstract: A frame synchronizing circuit utilizes dual signal loops for inhibiting a clock pulse generator for a given time duration. The first loop includes a timing pulse generator a frame synchronous pulse detector, the set input of a bistable device an output thereof and two inhibit logic gates. The second loop control includes a synchronous pattern detector, delay means, and the reset input to the bistable device. Such dual control loop is useful in digital communication system operating at a high clock frequency in which loop delay time is not negligible.

Device for cutting an outer layer of the concentric multilayer rod-like structure

Abstract: Apparatus for stripping a selected length of sheathing from a coaxial cable and the like. A die is positioned about the coaxial cable and a hollow cylindrical-shaped die is inserted beneath the sheathing to a depth commensurate with the amount to be stripped, accurate adjustment being controlled by an interior mounted slidable scale member. The two die members are brought into abrupt engagement with one another by being moved either linearly and/or rotationally relative to one another whereby the selected length of sheathing is stripped therefrom.

Time-division multiplex delta-modulation communication system

Abstract: In a time-division multiplex delta-modulation communication system, a frame of the multiplexed signal is composed of a plurality of subframes larger in number than the multiplexed transmission channels by at least one and defined by control bits, one of which is allotted to frame synchronization and the remainder of which are allotted to channel monitoring and the like. A respective one of the control bits is transmitted every frame period while the respective channel information is transmitted every subframe period.

Deep Energy Levels in the High Resistance Region at GaAs Vapor Epitaxial Film-Substrate Interface

Abstract: In order to find the energy levels of the deep centers that cause a high resistance region at the interface between GaAs vapor epitaxial film and the substrate, three kinds of measurements were performed: i) time dependence of the capacitance of Schottky barriers, ii) temperature dependence of the reverse current of Schottky barriers, iii) photoconductivity of the high resistance region. From the variation in the time dependence of the capacitance measured at various temperatures, an activation energy for electrons at deep traps was found to be about 0.89 eV. When the depletion layer contained a high resistance region, the reverse current of the Schottky barrier was larger than the normal reverse current by about three orders of magnitude. The measured results on the temperature dependence of reverse current and on the photoconductivity spectrum of the high resistance region suggest the presence of three deep energy levels that range from about 0.3 eV to 0.6 eV above the valence band. Extrinsic negative photoconductivity was observed in the high resistance region.

Effects of doping profile upon electrical characteristics of Gunn diodes

Abstract: A one-dimensional computer simulation of Gunn diodes with zero-impedance external load has been made for various nonuniform doping profiles including asymmetrical step-like ones, linearly graded ones, and a periodic square-wave one. The distances between the electrodes and the doping level are taken as 10 µ and an order of 1015cm-3, respectively. Current-voltage characteristics, oscillation current waveforms, oscillation frequency versus applied voltage characteristics, and electric field distributions as well as their dynamic changes were computed for the profiles with various parameters. The results show that with asymmetrical doping profiles, Gunn oscillation takes place when the cathode is on the higher resistance side, while for the opposite polarity it is difficult for the oscillation to occur. In the latter case, a static high-field domain is built up in the vicinity of the anode. The results also show that the voltage dependence of oscillation frequency is enhanced by an asymmetrical nonuniformity in the doping profiles. A considerable rise of the threshold voltage of the oscillations is found for the periodic square-wave profile. An experimental result is analyzed on the basis of the computed results.

Data signal transmission system employing phase modulation

Abstract: A data signal transmission system employing phase and amplitude deviation information comprising a transmitter including a source of an input data serial binary signal having a predetermined number of bits; means for converting the data signal into a plurality of parallel pulse signals, each representing one data signal bit, modulating means for phase deviating a carrier signal different angular amounts and indicating resultant vectors of combined vectors corresponding to phase deviations of the respective parallel pulse signals, and means for serially combining the carrier signal as phase deviated different amounts together with the resultant vectors to represent the input serial data signal; and a receiver including means demodulating the received serially combined phase deviated carrier signal together with the resultant vectors to reproduce the transmitter input data serial binary signal.

Coupled cavity-type slow-wave structure

Abstract: A slow-wave structure for a travelling-wave tube, comprising a tubular waveguide member, a plurality of electric conductive plates transversely affixed to the member and coaxially disposed in mutually spaced relation on a longitudinal axis of the member in a manner perpendicular thereto, the respective plates having aligned apertures for passing an electron beam therethrough and for propagating high-frequency energy in a state of electromagnetic interaction with the electron beam, and an attenuation section disposed substantially in the middle of the member and including two vessels disposed coaxially with the member longitudinal axis at juxtaposed ends of input and output sides of the member, at least a part of each of the vessels being made of high-frequency energy-permeable material, and water substantially filling the respective two vessels, whereby the high-frequency energy is attenuated in the respective vessels while the water therein serves as a coolant therefor.

Apparatus for the electronic selection and identification of characters

Abstract: A system for electronically selecting characters, one at a time, from a matrix including a plurality of different characters spaced in columns and rows, a computer providing predetermined binary code signals, indicating particular character rows and columns in which the preselected characters are located, converting the binary code signals into corresponding voltages including successively increasing steps, using the converted voltages to move an electron beam to final positions proximate to the preselected characters, and thereafter moving the electron beam in a coordinate pattern to scan the latter characters, one at a time, to transmit appropriate output ''''1'''' and ''''0'''' video signals identifying the latter characters.

Mos integrated circuit semiconductor device

Abstract: An MOS integrated circuit having a duplex insulating material structure wherein an aluminum oxide layer is disposed over the silicon oxide layer. Gate insulating material is protected against contamination from organic solvent and photoresist. In an n-channel device, the threshold voltage of the thick insulating material is increased to thereby reduce the likelihood of parasitic or leakage conduction between adjacent MOS transistors in the circuit.

Insulated gate type field effect semiconductor device having narrow channel and method of fabricating same

Abstract: A method for fabricating an integrated gate field effect transistor is disclosed wherein an induced conduction region is formed between the source and drain regions by the application of a suitable potential between the gate electrode and substrate. The surface of the device is irradiated by a high-energy beam, thereby to form a narrow channel in the conduction region which defines the gate channel of the field effect transistor.

Malfunction monitoring equipment for a time division multiplexed transmission system

Abstract: A malfunction monitoring system for the analog circuit of a time division multiplexed pulse code modulation system uses a noise signal as the pilot signal.

Signal switching device

Abstract: A signal switching device with a plurality of each of first and second groups of rectangular parallelopiped switching units arranged in X,Y, and Z directions. A plurality of first groups of spaced parallel conductors are disposed in said X direction in respective spaced X-Z planes of said first group units for multiply connecting of break terminals of corresponding switches in said respective first group unit stacks. A plurality of second groups of spaced parallel conductors are disposed in said Y direction in respective Y-Z planes for multiply connecting make terminals of corresponding switches of said second group units in said Y-Z planes. Input signal lines are disposed in parallel and connected to break terminals of said switches in respective first group units in said X-Z planes, while output signal lines are disposed in parallel and selectively connected to make terminals of switches of the second group units in the Y-Z planes, whereby a desired one of the input lines is connectable to a desired one of said output lines.

Semiconductor integrated circuit memory device utilizing insulated gate type semiconductor elements

Abstract: A semiconductor integrated circuit includes a plurality of insulated gate field effect memory transistors arranged in a rowcolumn matrix. Each of the memory transistors has an insulating film for establishing electron tapping centers. The source areas of the memory transistors are in the form of teeth-like projections which extend into the space defined between similarly formed projections in the memory transistor drain areas.

High speed associative memory circuits

Abstract: A high-speed associative memory circuit is disclosed comprising a flip-flop operating as a memory storage circuit, and a pair of switching transistors connected to the "true" and "not" output terminals of the flip-flop. The latter transistor pair thus defines a circuit for detecting the state of the flip-flop transistors.

Heat transfer analysis of beam-lead transistor chip

Abstract: The program package which is applicable to solve problems of heat transfer in transistors or integrated-circuit chips or in their stems has been developed with a three-dimensional lumped network model. The thermal resistances of beam-lead transistors calculated with this program are found to be in good agreement with the observed values. For the better design of beam-lead devices, thermal resistances are evaluated with this program for various geometries of the chips and for the passivation films of 1-micron thick SiO 2 , 2-micron SiO 2 , and 0.2-micron Al 2 O 3 or Si 3 N 4 on 1-micron SiO 2 . The results calculated indicate that the thermal resistance is mainly dependent on the thickness of electroplated Au in the beam-lead structure, and that the heat dissipation is especially sensitive to the distance, which is measured along the beam lead from the chip edge to the nearest end of the joining part of the beam lead to the metallized conductor on the ceramic stem.