Showing papers by "NEC published in 1979"

Two-level DP-matching--A dynamic programming-based pattern matching algorithm for connected word recognition

Abstract: This paper reports a pattern matching approach to connected word recognition. First, a general principle of connected word recognition is given based on pattern matching between unknown continuous speech and artificially synthesized connected reference patterns. Time-normalization capability is allowed by use of dynamic programming-based time-warping technique (DP-matching). Then, it is shown that the matching process is efficiently carried out by breaking it down into two steps. The derived algorithm is extensively subjected to recognition experiments. It is shown in a talker-adapted recognition experiment that digit data (one to four digits) connectedly spoken by five persons are recognized with as high as 99.6 percent accuracy. Computation time and memory requirement are both proved to be within reasonable limits.

Lateral transverse mode instability and its stabilization in stripe geometry injection lasers

Abstract: A numerical analysis has been carried out on the behavior of semiconductor injection lasers with a stripe geometry double-heterostructure, taking into account spatial hole-burning and its effect on the waveguiding. It is shown that spatial hole-burning, the negative dependence of refractive index eta on the excited carrier density n (d_{eta}/ dn , and the lack of complete symmetry in any real laser structure are the three critical factors responsible for the lateral mode instability leading to such anomalous behaviors these lasers exhibit as a "kink" in the light output versus current relation and the lateral shift in the emission spot. Effects of rigid refractive index and gain-loss profiles built into the laser crystal on the mode stability have been examined, and conditions for kink-free, single lateral mode oscillations have been investigated.

One-dimensional logic gate assignment and interval graphs

Abstract: This paper gives a graph-theoretic approach to the design of one-dimensional logic gate arrays using MOS or I^{2}L units. The incidence relation between gates and nets is represented by a graph H=(V,E) , and a possible layout of gates and nets is characterized by an interval graph \hat{H} = (V, E \cup F) , where F is called an augmentation. It is shown that the number of tracks required for between-gate wiring is equal to the clique number (chromatic number) of H , and hence the optimum placement problem is converted to that of minimum clique number augmentation. This turns out to be an NP -complete problem. Instead a polynomial-time algorithm for finding a minimal augmentation is presented, where an augmentation is minimal if no proper subset of it is an augmentation. An algorithm for gate sequencing with respect to a given augmentation is also presented.

An Improved Computational Method for Noise Parameter Measurement

Abstract: Conventional methods for noise parameter measurement for linear noisy two-ports have been improved by introducing a computational method for evaluating measured admittance errors. Derivation and comparison with a conventional method are given. Noise parameters of a packaged 0.5-mu m gate-length GaAs MESFET (NE38806) were successfully measured using the proposed technique.

Mechanical optical switching device

Abstract: The mechanical optical switching device comprises an input optical fiber with a collimating lens (5) and a first and a second output optical fiber each with a converging lens (6 and 7, respectively) at the respective terminal ends. Further there are provided a movable first optical path-changing means (8) and a fixed second and a fixed third optical path-changing means (12 and 13) associated to the first and second output fiber, the three path-changing means (8, 12 and 13) comprising two reflecting surfaces each. For performing the switching operation the first optical path-changing means (8) may be inserted into the optical axis of the collimating input lens (5) or removed therefrom. In the removed position the input beam is directed towards the second output fiber via the third path-changing means (13) and the second output lens (7), and in the inserted position the input beam is directed towards the first output fiber via the first path-changing means (8), second path-changing means (12) and the first output lens (6) Preferably the first path-changing means (8) is a parallelogram prism with the two reflecting surfaces opposite to each other and the second and third path-changing means (12 and 13, respectively) are triangle prisms.

An AlGaAs window structure laser

Abstract: Extremely high optical power density emission was achieved with an AlGaAs "window structure" laser in CW operation as well as pulsed operation by increasing the threshold of the catastrophic optical damage (COD) on mirrors. A Zn diffused "window stripe" laser consists of the Zn diffused p-type light emitting region with low effective energy gap in the central part and the n-type window regions with high effective energy gap at both ends of the cavity. The maximum available optical power in pulsed operation was at least one order of magnitude higher than the COD threshold in conventional structures. 80 mW optical power in CW operation was achieved in the Zn diffused window stripe laser with a 5 μm wide stripe. Furthermore, gradual degradation due to the photoenhanced mirror oxidation has been reduced significantly under long term CW operation.

Tem study of dark line defect growth from dislocation clusters in (GaAl)As-GaAs double heterostructure lasers

Abstract: Dark spot defects in (GaAl)As-GaAs double heterostructure lasers are studied by transmission electron microscopy and found to be a cluster of dislocations generated in the first (GaAl)As epitaxial layer during epitaxial growth. Burgers vectors and spatial configuration of dislocation dipoles developing from these dislocations are determined. It is found that Burgers vectors of dislocations in the dislocation cluster obey the Burgers vector sum rule.

Digital video effect system comprising only one memory of a conventional capacity

Abstract: In a digital video effect system, only one one-frame RAM (30) produces a mixed and phase-locked signal (14) for n individually synchronized input television signals (11, 12) when read by horizontal and vertical address signals (48, 49) derived from a reference timing signal (15) in synchronism with horizontal and vertical synchronizing pulses included therein. Digital video signals (39') and vertical address signals (29') derived from n or (n-1) input television signal or signals are written in n or (n-1) four-line RAM (80) by horizontal address signals (28') derived also therefrom and read by horizontal address signals (48 or 28) derived either from the timing signal or one of the n input television signals. Thus horizontally phase-locked digital video signals (39, 83) are written in the one-frame RAM by the last-mentioned horizontal address signals and likewise horizontally phase-locked vertical address signals (29, 84).

A new polysilicon process for a bipolar device—PSA technology

Abstract: A new polysilicon process has been developed to obtain high packing density, high speed, and low-power LSI's. The new process, called the polysilicon self-aligned (PSA) method is based on a new fabrication concept for dimensional reduction and does not require fine patterning and accurate mask alignment. For an application example of this new method, an emitter-coupled logic (ECL) gate with 0.6 ns delay time, 0.5 pJ power-delay product, and 6400 µm2gate area has been achieved. Futhermore, by introducing a polysilicon diode (PSD) and Schottky barrier diode (SBD) to the PSA method, a low-power Schottky-diode-transistor-logic (SDTL) gate with 1.6 ns delay time, 0.8 pJ power-delay product, and 2000-µm2gate area has been successfully developed.

A new polysilicon process for a bipolar device-PSA technology

Abstract: A new polysilicon process has been developed to obtain high packing density, high speed, and low-power LSIs. The new process, called the polysilicon self-aligned (PSA) method is based on a new fabrication concept for dimensional reduction and does not require fine patterning and accurate mask alignment. For an application example of this new method, an ECL gate with 0.6 ns delay time, 0.5 pJ power-delay product, and 6400 /spl mu/m/SUP 2/ gate area has been achieved. Furthermore, by introducing a polysilicon diode (PSD) and Schottky barrier diode (SBD) to the PSA method, a low-power Schottky-diode-transistor-logic (SDTL) gate with 1.6 ns delay time, 0.8 pJ power-delay product, and 2000 /spl mu/m/SUP 2/ gate area has been successfully developed.

LED Pulse response analysis considering the distributed CR constant in the peripheral junction

Abstract: An improved equivalent circuit of a current crowding type LED is proposed to explain the LED pulse response behavior, taking into account the junction capacitance and the spreading resistance distributed over the entire junction area. Calculated results based on this model can consistently explain the experimentally observed LED behavior, including dc-bias effects and pattern effects, which occur in high-speed pulse modulation.

Threshold difference compensated sense amplifier

Abstract: A dynamic flip-flop sense amplifier compensating for threshold difference between a pair of transistors by way of offset storage technique is presented. The DC and AC analyses on input offset voltage and performance limitations are discussed. Experimental results have shown that input offset is less than 2 mV with a 5 V single power supply, over a wide temperature range and a wide common mode input voltage range.

Encoding device comprising predictors for thinned and unthinned patterns

Abstract: For selectively carrying out predictive encoding of an original pattern of a first tone on a background of a second tone and a thinned pattern having, in effect, the first tone on its background corresponding to the second tone, a device comprises a predictor responsive to a set of sample pulses representative of a few picture elements selected from those sampled from the original pattern and its background for producing each of prediction error pulses of a sequence, another predictor responsive to a set of pre-processed pulses representative of several picture elements selected from those sampled, in effect, from the thinned pattern and its background for producing each of error pulses of another sequence, a selector for selecting one of the original and the thinned patterns and consequently one of the predictors to produce a selection code indicative of the selected predictor, and an encoder for encoding the error pulses produced by the selected predictor into an encoded signal including the selection code. Preferably, each predictor is operable to produce for each error pulse a mode code indicative of one of two or more groups into which all allowable permutations of at least one of the two tones of the selected picture elements are classified and, in comsideration of which, codes are predetermined for all possible durations of same error pulse. The encoder uses the mode code for the respective error pulses in selecting some or all of the predetermined codes and arranges the selected codes in a predetermined order.

Magnetoresistive pressure-sensing device for automotive electronic engine control systems

Abstract: A pressure sensor comprises essentially magnetoresistive elements formed on a diaphragm serving as a stress magnifier. The diaphragm may be made, for example, of glass in a thickness of 0.5 millimeter, and the magnetoresistive elements can be formed thereon in any desired pattern of thin stripes by ordinary thin-film techniques. Such sensor elements can be mass produced, e.g., by vapor deposition and etching on a large sheet of diaphragm material and cutting into chips of desired shape and size.

Digital facsimile transmission system for screened pictures

Abstract: A digital facsimile system suitable for the facsimile transmission of newspaper pages having screened picture portions and printed character portions is disclosed. The transmitter receives a digitized facsimile signal which is a train of pel codes formed by scanning a picture to be transmitted. In response to the digitized facsimile signal, a first reference generator produces first pel codes neighboring the present pel code, a second pel code spaced by the pitch of the screened picture from the present pel code, and third pel codes neighboring the second pel code. A ROM is addressed by the first, second and third pel codes to produce a first prediction code for the present pel code. The output of the ROM and the digitized facsimile signal are supplied to an Exclusive OR which provides a prediction error code according to the difference between the first prediction code and the present pel code. A train of prediction errors codes constitutes a prediction error signal which is encoded and transmitted. The receiver receives the encoded prediction error signal and decodes it to reproduce the prediction error signal. Another Exclusive OR produces the present pel code from each error code of the prediction error signal. A second reference code generator produces a second reference code corresponding to the first reference code on the basis of the output of the second Exclusive OR. A second ROM produces a second prediction code corresponding to the first prediction code on the basis of the second reference code and applies the second prediction code to the second Exclusive OR.

Stable transverse mode oscillation in planar stripe laser with deep Zn diffusion

Abstract: The guiding mechanism in a planar stripe laser with deep Zn diffusion under the lasing conditions was investigated both theoretically and experimentally. The conditions necessary to realize refractive index guiding depend on a combination of electron and hole concentrations. The lasers under refractive index guiding, whose stripe width is less than twice the diffusion length, with an adequate combination of electron and hole concentrations, show stable fundamental transverse mode oscillation up to three times the threshold current level.

Luminance/chrominance separating apparatus having a spatial filtering effect

Abstract: Luminance/chrominance separating apparatus in which a luminance signal and chrominance signal are extracted from a composite color television signal by a comb filter. A low frequency signal component is extracted from the chrominance signal and passed through a variable attenuator. The low frequency signal component from the variable attenuator is added to the luminance signal to produce a compensated luminance signal.

787 BPM/40 TPM feasibility of a plated disk

Abstract: A plated disk, which consists of a chemically plated Co-Ni-P medium and a newly developed and spin-coated overcoat, was prepared using techniques based on extensive studies on error defects throughout the production process. Plated disk 787 BPM/40 TPM feasibility was experimentally evaluated. Read/write characteristics and total phase shift were measured with a 15μm track width Mn-Zn ferrite head at a 787 BPM linear density. The numbers of errors were measured with 30 μm track width heads at 350 BPM and 635 BPM linear densities. Wear durability was determined for 30,000 contact start/stop (CSS) cycle tests with IBM-3340 compatible and narrower track width heads. From the results, it was concluded that the 787 BPM/40 TPM recording density can be accomplished with the plated disk and a conventional narrow track width Mn-Zn ferrite head.

Adaptive electronic hybrid circuit

Abstract: An adaptive hybrid circuit for connecting two-wire and four-wire telephone transmission lines to minimize singing, oscillation or echoes due to impedance mismatch. The circuit comprises a variable impedance circuit connected between the two-wire and four-wire circuits. In one embodiment one end of the variable impedance circuit is connected to the two-wire circuit and to one input of an adder to which the reception signal from the four-wire circuit is also applied and compared in reverse phase and half amplitude. The resulting transmission signal is used to adjust the variable impedance circuit so as to minimize the transmission signal. In another embodiment the variable impedance element is connected to an impedance through which the four-wire reception signal is applied and is further connected to one input of an adder which compares this input in reverse phase with the two-wire signal to produce a transmission signal. This transmission signal is also used to adjust the variable impedance circuit to minimize the transmission signal.

Dot matrix type printer

Abstract: An improved dot matrix type printer including a carriage mechanism for a printer head having a plurality of printer elements aligned immediately before a platen adapted to carry a sheet of paper to be printed and along a direction parallel to the axis of the platen, the carriage mechanism comprising a balancing mass, a first resilient member which is adapted to connect the balancing mass to the printing head, and a second resilient member which is adapted to connect the balancing mass to a base structure member.

Muting circuit with operational amplifier

Abstract: An FM muting circuit has a common input terminal and uses an operational amplifier which has a pair of input terminals. The two amplifier input terminals are coupled to the common muting circuit input terminal. An electronic switch is connected between ground and one of the operational amplifier input terminals. When the muting circuit receives an input signal which is free of noise, a "high-level" control signal is developed to switch the electronic switch into a saturated condition, thereby grounding one of the operational amplifier input terminals. Thereafter, the operational amplifier amplifies only the signal applied from the common input terminal of the muting circuit to the other amplifier input terminal, with a resulting amplified output signal. However, when noise appears in the input signal received by the muting circuit, a "low-level" control signal is applied to the electronic switch and it turns off. The signal appearing at the common input terminal of the muting circuit is thereafter supplied, in phase, to both amplifier input terminals, which causes a cancellation therein. The operational amplifier output signal is then about 100dB below the conventional level, thereby effectively rejecting the signal containing noise. A resistor network at the two inputs of the operational amplifier prevents any substantial change of bias potential responsive to the electronic switch operations. The elimination of such a bias potential change also eliminates the popping noise and causes the switching operation of the muting circuit to occur very fast.

A new self-aligned source/drain diffusion technology from selectively oxidized poly-silicon

Abstract: A novel self-aligned source/drain diffusion technology suitable for high density n-channel MOS LSI's is proposed. Gate regions and source/drain junctions are formed simultaneously by the selective oxidation of a phosphorous doped poly-silicon layer. A short channel device with a flat surface and self-aligned contact openings is realized based on this technology. Utilizing these advantages, a microcomputer CPU chip is successfully fabricated.

Anisotropic interactions between mbba and surface-treated substrates

Abstract: Easy axis Θ and anchoring strength coefficient Bθ were measured on the interfaces between MBBA and substrates with various surfactants layers, by using wall effects on the Freedericksz transition. Experimental results indicate that steric, dispersive and polar interactions play individual roles in the molecular orienting forces of surface-treated substrates. Bθ values were found to be rather small. MBBA surface tension anisotropy was estimated to be of the order of 10-2 dyn/cm.

A Two-Dimensional Placement Algorithm for the Master Slice LSI Layout Problem

Abstract: This paper deals with the optimum placement of blocks on a two-dimensional cell-array, which minimizes the total routing length of signal sets. A new heuristic procedure, based on iterative improvement, is proposed. The procedure repeats random generation of an initial solution and its improvement by a sequence of local transformations. The best among the local optimum solutions is taken as a final solution. The iterative improvement method proposed here is different from the previous one in the sense that it considers interchanging more than two blocks at the same time and examines only a small portion of feasible solutions which has high probability of being better. Experimental results show this procedure gives better solutions than the best one up to now. The computation time for each local optimum solution grows almost linearly with regard to the number of blocks.

Special effect device for electronically accomplishing a gradual scene shift

Abstract: In an electronic special video effect device, first and second digital video signals (D F and D S ) derived during a keying interval of time from two television signals (VA and VB) between the beginning and a switching instant of each predetermined period and between the switching instant and the end of the period, respectively, are written in a memory (35) in addresses corresponding to the respective periods starting at an initial address corresponding to the switching instant. Each period may be a horizontal or a vertical scanning period. The memory addresses are merely cyclically read out to provide an output signal (VD) that enables a scene represented by one of the television signals to be pushed away from a television screen by another scene represented by the other, leftwards, rightwards, downwards, or upwards. Read-out may be started at the initial address with write-in carried out merely cyclically. Both may start at the initial address.

Two-term vector multiplier

Abstract: A two-term vector multiplier for calculating Ax+BY and useful in FFT and digital filter circuits is disclosed. The variables A and B are converted into standard type-minimal representation codes which are then operated upon to generate selection signals and an addition-subtraction control signal. The selection signals select one of four values, X, Y, Y/2 and O, to be sent to an accumulator where the selected value is either added to or subtracted from one half the value presently in the accumulator to provide a new accumulator value. The final accumulation value is Z=AX+BY.

Bidirectionally propagating fast access bubble memory chips

Abstract: Bidirectional propagation bubble memory chips have been successfully realized as 78 kb memory chips with 3μm bubbles and 14μm period symmetrical Y-Y propagation patterns. The chips are markedly characterized with the following functional patterns: (1) Transfer gate Ni-Fe patterns with complete symmetry. (2) Operation with no guard rail pattern around the memory area. (3) Collapsing type bubble annihilator. Chips are mainly fabricated in dry etching processes on an (YSmLuCa) 3 (FeGe) 5 O 12 LPE garnet film. Bias field operation margins greater than 18 Oe have been obtained for all functions, including bidirectional bubble propagation in minor loops in a 50 Oe rotating field at 300 kHz within a 0-100°C temperature range. Operation with no guard rail at all is guaranteed by the employment of a thin Ni-Fe detector, set in a major loop, and the collapsing annihilator. The detector, gives an output voltage of 14 mV/2mA at 25°C and -0.29%/°C temperature coefficient. A 64 kB memory system, capable of bidirectional accessing, has been developed using the 8 chips in four 128 kb modules. An average access time of 0.4 msec has been obtained.

Super low noise GaAs MESFET's with a deep recess structure

Abstract: Super low noise GaAs MESFET's for replacement of parametric amplifiers have been successfully developed by utilizing an electron beam lithography technique and by adopting a deep recess structure. The noise figure of less than 2.0 dB at 12 GHz has been reproducibly achieved by the structure of a 0.5 µm gate in a deeply recessed region because the source resistance was reduced to a half of that of a conventional flat type MESFET by this structure. The best noise figure was 1.68 dB with 10.7 dB associated gain at 12 GHz. The developed MESFET's were applied to 2- stage amplifiers of 11.7-12.2 GHz band, and the noise figure obtained was 2.16 dB (Te: 185 K) at the room temperature and 1.94 dB (Te: 163 K) at 0°C. This performance is enough to replace some of the parametric amplifiers.