Showing papers by "NEC published in 1967"

The di/dt capability of thyristors

Abstract: This paper describes an experimental investigation of the di/dt failure mechanism of thyristors. The location of the initial turn-on region and the spread of the "on" region were observed on a specially designed thyristor having many monitoring electrodes. The turn-on process was studied for triggering by gate, by breakover, and by dv/dt. In many cases it was found that turn-on occurred at almost the same region, whether it was triggered by breakover or by dv/dt. This area coincided with the final holding position in the turn-off process. The di/dt capability of the thyristor was measured. It was found that the capabilities were almost the same for the three triggering methods. The destruction temperature in the di/dt test was estimated from the area of the burn-out spots and the energy dissipation.

Photosensitive Electron Spin Resonance of Sn 3+ in Zinc Sulfide

Abstract: Electron spin resonance due to ${\mathrm{Sn}}^{3+}$ in hexagonal ZnS crystal has been examined. The signal is much enhanced with uv excitation and quickly decreased by irradiation of light of around 550 m\ensuremath{\mu}. It is found that $g=2.0075\ifmmode\pm\else\textpm\fi{}0.0005$, and that $|A|=0.5207\ifmmode\pm\else\textpm\fi{}0.0005$ ${\mathrm{cm}}^{\ensuremath{-}1}$ for ${\mathrm{Sn}}^{117}$, and $|A|=0.5448\ifmmode\pm\else\textpm\fi{}0.0005$ ${\mathrm{cm}}^{\ensuremath{-}1}$ for ${\mathrm{Sn}}^{119}$. The sign and the order of magnitude of the observed $g$ shift are well interpreted by the previously proposed model that the $g$ shift of substitutional trivalent impurity of Group-$\mathrm{IV}B$ elements in ZnS is mainly caused by the processes of charge transfer into the ligand anions through the spin-orbit interaction. The correlation of photosensitivity of resonance signals with luminescence is discussed.

Phase-locked pulse generator with frequency maintaining function

Abstract: A phase-locked pulse generator for producing clock pulses for reception of digital signals including timing information of varying density and comprising a sampling type phase comparator and a low pass filter for temporarily holding, in the case of a reduction in the timing information density, the timing information detected by the phase comparator. Due to this holding action, the frequency of the pulse generator is controlled by the output of the low pass filter and is maintained substantially unchanged even when the timing information is not continually included in the digital signal.

An integrated MOS transistor associative memory system with 100 ns cycle time

Abstract: Since the announcement of the development of a technique for using MOS transistor integrated circuits as associative memory cells, 128 words of 48 bits per word associative memory has been experimented and engineered.

Switching device for magnetic recording/reproducing apparatus

Abstract: The disclosure broadly teaches a switching device for rotary recording/reproducing systems preferably of the magnetic tape variety wherein signals picked up by the multiple rotating heads are composed by switching means into a continuous composite signal. Conventional switching apparatus of the alternating black-white ring and accompanying photocell reading assembly is employed for initially composing signals from selected heads into a partial composite signal. The partial composite signals are then composed into a final continuous composite signal by use of wave envelope detecting means for detecting the envelope of any one of the signals reproduced by the read heads and forming shaped pulses or combining the initially composed signals into a final composite continuous signal in a very high precision manner.

Phase detection and synchronizing system for facsimile and the like

Abstract: An automatic phase detection and synchronizing means for phototelegraphy, or facsimile systems and the like in which phase signals are conventionally transmitted as amplitude modulated carrier signals in advance of facsimile signals. In order to determine whether phase signals are being transmitted, the instant invention provides a device for determining the presence of phase signals by developing signals representative of the phase signals and comparing them with incoming phase signals which have not undergone detection, for the purpose of automatically synchronizing the operation of the revolving drum employed in facsimile systems with the rotational rate dictated by the receipt of a group of noise free phase signals received from a remote transmitter.