Hirotsugu Arai

Energy-band gap in SiAsTe amorphous semiconductors

Abstract For any composition in semiconducting SiAsTe glasses, it is found that the energy-band gap (ΔE) is determined as a function of the glass transition temperature (Tg) or the glass softening temperature (Ts) by the empirical equation; Tg = T1 exp (β·ΔE) or Ts = T2 · exp (β·ΔE), respectively, where T1 = 178 ± 5°K, T2 = 190 ± 5°K and β = 0.75 ± 0.02 eV−1.

Relation between electrical and optical gaps of amorphous semiconductors in the SiAsTe system

Abstract Electrical and optical properties of semiconducting SiAsTe glasses have been investigated. Compositional dependences of the properties in the SixAsyTez system are examined as a function of atomic percentage x (or y, z) of one element with parameters of constant atomic ratio y/z (or x/z, x/y) of the other two elements. A pre-exponential factor σ0 in the dc conductivity formula is estimated to be (2.1 ± 0.6) × 10 4 (Ω · cm ) −1 , inependently of the compositions. A systematic relationship between the compositional changes in the electrical gap Eg(el) and optical gap Eg(op) has been found. The energy gaps increase linearly with increasing Si content and decreasing Te content, but are almost independent of As content. The relation between Eg(el) and Eg(op) is expressed by Eg(el) = 1.60 Eg(op) − 0.15 in eV. On the other hand, the optical absorption coefficient α(Ω) near the band edge follows the empirical formula, α(Ω) = α 0 exp ( h Ω/E s ). The experimentally determined factor Es increases linearly with Eg(op) and is closely related to the energy difference between the two gaps. A tentative model to explain these experimental results is proposed by taking into account of the effect of the potential fluctuations in such disordered materials.

Energy-band gap and density of SiAsTe amorphous semiconductors

Abstract In the SiAsTe glass system, a proportional relationship is found between the energy-band gap (Δ E ) and the density at 25°C (ϱ 25 ; Δ E = E O - α δ ϱ 25 , where E = 4.5 ± 0.1 eV and α = 0.65 ± 0.01 eV δ cm 3 /g. The glass-composition dependence of Δ E and ϱ 25 suggest that it results from the short-range chemical and structural order due to the SiTe covalent bonds in these semiconducting glasses.

LARGE AREA LIQUID CRYSTAL DISPLAY FOR AUTOMOBILE

An instrument panel of a large area liquid crystal display (LCD), including a 50 segment bargraph speedometer, a six digit odo/trip/tacho meter, two gages and several warning indicators, has been developed. The LCD cell evaluated for this instrument panel is operated in a reflective twisted nematic mode and dimensions of the cell are 260 X 110 X 3 mm. The liquid crystal material is capable of operating over a wider temperature range from -30 deg C to 80 deg C and the response time is less than 1 second at -20 deg C without heaters. The LCD instrument panel can display in multicolor by using high performance dichroic polarizers. Finally feasibility of the large area LCD instrument panel is investigated.

22.1: Automotive Navigation Display System

Vehicle Information Systems, of which the In-Car Navigation System is representative, are widely used in Japan. The market volume reached over a million per year in 1997 in Japan, even though it is only 10 years since practical navigation systems appeared. In this paper, briefly introduce the recent developments in technologies and display contents used in In-Car navigation systems in Japan. and also introduce a practical analysis of quantity of information which is included in route guidance map display. This analysis was carried out for the purpose of distributing the safe and easy recognition contents.

Hot film type fuel flow sensor

A new type fuel flow sensor which is based upon heat transfer principle has been developed for automotive applications. The fuel flow sensor presented in this paper utilizes temperature sensitive resistors made of extremely thin platinum films, and is located in the main passage of a conduit opposite to a nozzle. An extraordinarily wide dynamic range and a quick response have been obtained in comparison with conventional methods. The hot film type fuel flow sensor could allow a new microprocessor to control the engine functions, as well as a fuel consumption or a fuel rate meter.

Improved Temperature Coefficient of Threshold Voltage in Twisted Nematic Liquid Crystals

Abstract This work is concerned with reducing temperature dependence of the threshold voltage of the TN nematic liquid crystals which consist of majority of n-type base mixtures and minority of p-type additives. The temperature coefficient of threshold voltage is closely related to the effective component of permanent dipole moment per molecules of p-type additives and becomes smaller with increasing it. The temperature coefficient is independent of the concentration of p-type additives. The mixture, whose temperature coefficient is 0.16%/ ° C or -3mV/° C, is developed for seven to-one multiplexing scheme over the temperature range 0 ∼ 40° C without any temperature compensation circuit.

Liquid CrystalDisplays for Automotive Instrument Panels

Abstract Electronic displays are becoming more important for automotive instrument panels because of the need to save space and energy. Liquid crystal displays (LCDs) provide many advantages, such as the capacity to produce thin panels, no wash out in bright ambient light and flexibility of pattern design. The recent improvement of LCDs resulted in a wide operating temperature range of −30°C to +85E°C, a good response time of less than 1 s at −30°C and a long life of more than 10 years. Since the first practical application of LCDs which was introduced in car-clocks in 1980, we have seen some applications in other automobile parts. In 1982, LCDs were introduced in instrument panels. The twisted nematic liquid crystal display (TN-LCD) is a suitable display technology for automotive applications because of its high contrast, short response time, and high reliability. Because of this good visibility and reliability, they will be used more in automobiles in the near future.

Microcomputer-Controlled Liquid Crystal Display for Automobiles

This paper presents a microcomputer-controlled liquid crystal display (LCD) speedometer with a digital seven-segment display here the response time is improved by a new driving technique employing phase control.