Abstract: This normally-off mode polarization super junction GaN-based field effect transistor has an undoped GaN layer 11, an AlxGa1-xN layer 12 (0<x<1), an island-like undoped GaN layer 13, a p-type GaN layer 14, a p-type InyGa1-yN layer 15 (0<y<1), a gate electrode 16 on the p-type InyGa1-yN layer 15 and a source electrode 17 and a drain electrode 17 on the AlxGa1-xN layer 12. When the polarization charge amount of the hetero-interface between the AlxGa1-xN layer 12 and the undoped GaN layer 11 and the hetero-interface between the AlxGa1-xN layer 12 and the undoped GaN layer 13 is denoted as NPZ and the thickness of the AlxGa1-xN layer 12 is denoted as d, NPZ d?2.64×1014 [cm?2 nm] is satisfied.

Abstract: A thin-type photoelectric smoke detector which is less susceptible to the effect of disturbance light noise, contamination of a smoke detecting unit, etc., and which ensures high sensitivity for the optical detection characteristic of the smoke detecting section. In the photoelectric smoke detector of the type in which infrared light is irradiated into a flat smoke detecting chamber and the scattered light of the irradiated infrared light due to smoke entering into the smoke detecting chamber is detected by a light-sensing element, there are provided optical members for expanding the visual field of the light-sensing element to a flat visual field corresponding to the cross-sectional shape of the smoke detecting chamber.

Abstract: A method for driving a supersonic motor includes the steps of driving the supersonic motor by supplying a driving voltage of greater frequency than a resonant frequency (point) to a driving piezoelectric electric element. The driving frequency is decreased when a wave form distortion is not generated in an output signal of an oscillation detection piezoelectric element provided in an elastic body. The driving frequency is increased when a wave form distortion is generated in the output signal of the oscillation detection piezoelectric element.

Abstract: An air damper operating system for vehicle air conditioners with a plurality of ultrasonic motors. An oscillator circuit, phase shifter and feedback circuit control the frequency of an oscillator of a motor. A feedback signal transfer switch, position sensors and a time-division switching circuit operate the motors until they are rotated to predetermined positions.

Abstract: A scattered-light smoke detector having an improved shield structure. A detector circuit is provided on a printed circuit board which is disposed at an upper portion of a smoke detecting section. The smoke detecting section includes a planar base and a surrounding wall extending downwardly from a lower surface of the base and having an opening or openings which allows or allow smoke to enter therethrough. The surrounding wall defines a smoke detecting space therein. A light emitting element and a photodetector element which are disposed at positions where they are not opposite each other and optical axes thereof intersect each other at a predetermined angle and said photodetector element can receive light from the light emitting element scattered by smoke entering the smoke detecting space. The printed circuit board is attached on an upper surface of the base. A shield layer is interposed between said printed circuit board and said base.

Abstract: A photoelectric smoke detector of this invention comprises a smoke-detection arrangement including a light emitting element and a photodetecting element and a smoke-detecting unit on which said smoke-detection arrangement is mounted. The smoke-detecting unit includes a base plate to which said smoke-detection arrangement is attached and a peripheral wall having such a configuration that allows smoke to enter from the outside, but substantially prevents light to enter from the outside. The peripheral wall is formed of a plurality of wall elements, each of said wall elements is arranged substantially regularly and formed integrally with said base plate so as to extend downward from the base plate. The smoke-detecting unit further includes an insect net which has been fixed to the outer surfaces of the wall elements in the shaping process of the smoke-detecting unit so as to be fit around the outer periphery of the peripheral wall.