抄録
The high speed fail safe element is an urgent need of the day, especially in the field of traffic control such as that used on a railway or a highway. This is because the present magnetic relay control system widely used in the market may become unsatisfactory as the required control speed is drastically increasing. Few kinds of electronic fail safe elements have been reported, one is the fail safe threshold logical operational oscillator using resistors and semiconductors whose output voltages+V and -V (|V|>threshold voltage) correspond to the truth values 1 and 0 respectively, and the voltage less than the threshold voltage corresponds to the truth value 1/2. Another is the subharmonic oscillator called parametron whose 0 and π correspond to the truth values 0 and 1 respectively. The failure of an element and a circuit resulting in no voltage is covered by the following element whose constant signal is always monitored. The operational oscillator is excellent in the idea but the element is complicated and expensive, the subharmonic oscillator is simple but large in size and slow in speed because of the ferrite core.
Here aiming at accuracy, high speed, small size and low cost, we haved eveloped a thin permalloy film parametron to replace the ferrite parametron. The permalloy film is deposited onto a piece of phosphorous bronze wire 0.47mm in dia.. The film is 1μm thick and has a composition of 81 Ni-Fe with uniaxial anisotropy in circumference, and the anisotropy magnetic field is about 200AT/m. To investigate the quality, we built a fail safe control equipment using 325 thin film parametron elements and 28 magnetic control relays. As a result of this study, we find the fail safe element using thin film parametron is very accurate under a clock frequency of 50kHz and is cheap and small.
