Jiro Terada

Multifunctional ceramic sensors: Humidity-gas sensor and temperature-humidity sensor

Two types of multifunctional ceramic sensors have been developed in response to strong demands for automatic control systems in cooking ovens, air conditioners, etc. The first sensing device can detect both humidity and particular reducing agents, such as alcohols and smokes, with a high sensitivity and selectivity. This novel ceramic sensor utilizes gas chemisorption at 400°-500°C as well as water physisorption at <150°C on the grain surface of MgCr2O4-TiO2ceramic with a porous structure and p-type semiconduction. The other sensor is composed of a porous dielectric Ba0.5MSr0.5TiO3ceramic characterized by a high temperature dependence of the dielectric constant. The sensing device can independently detect simultaneously and rapidly both temperature and humidity. These sensors exhibit long-term stability, in combination with heat treatment.

Application of Frequency-Change-Type Single-Crystal Silicon Acceleration Sensors to Inclination Angle Sensor

A new single-crystal silicon inclination sensor using a frequency-change-type acceleration sensor is proposed here. The sensor utilizes the phenomenon showing that the resonance frequency of a bending vibrator changes with axial force. The one-axis sensor element used is composed of one developed bending vibrator, a mass, support bars, and a frame for fixation, and the two-axis sensor element has two vibrators. The volumes of these sensors are about 4.0 ×4.28 ×0.5 and 4.0 ×4.2 ×0.5 mm3, respectively. The first out-of-plane vibration mode in the vibrator is used, and the resonance frequencies of these sensors are about 19.8 and 80.8 kHz, respectively. Acceleration sensors can also be applied to an inclination angle sensor under a gravitational field. The characteristics of the sensors are analyzed using the finite-element method and confirmed experimentally.

Angular velocity sensor having a tuning fork construction and its method of manufacture

The present invention relates to an angular velocity sensor utilized as a gyroscope and particularly, to a high-performance angular velocity sensor having a tuning-fork construction. The vibrator is formed of a metal base plate which is bent about 90 degrees along a center line defined by two opposite slits extending from their respective side edges to a central region of the metal base plate so that its two bent parts are orthogonal to each other. Two piezoelectric elements are bonded to the corresponding surfaces of the two parts of each vibrator which in turn serve as an actuator and a detector.