Abstract: A hybrid type stepper motor preferably includes a two-phase eight-main-pole stator and a rotor defined by two rotor units each having a pair of rotor magnetic poles with a permanent magnet interposed therebetween. Each rotor magnetic pole has fine teeth at a regular pitch. The permanent magnets are magnetized in opposite directions to each other. The adjacent rotor magnetic poles of the rotor units are arranged with their fine teeth aligned with each other in the axial direction. Each main pole has six inductor teeth including: a pair of innermost inductor teeth arranged at the first pitch in the central portion of the main pole; a pair of intermediate teeth on the outside of the innermost inductor teeth at the second pitch therefrom; and a pair of outermost inductor teeth on the outside of the intermediate inductor teeth at the third pitch therefrom. The first, second, and third pitches are all different from the pitch of the fine teeth of the rotor magnetic pole.

Abstract: A micro switch is mounted onto a mounting base attached to a controller of an automatic icemaker. The micro switch generates a signal for controlling the amount of water to be filled in an ice tray. The micro switch is fixed to the mounting base by the first fixing member and the second fixing member. The first fixing member is inserted through a mounting hole formed in a case of the micro switch. The second fixing member is arranged on a surface of the mounting base on an opposite side of a surface mounted with the micro switch, and is fixed to the first fixing member.

Abstract: A stepping motor includes: a stator having main magnetic poles each having small stator teeth on its tip, a core-back portion that connects outer portions of the poles, and windings wound around the poles; and two sets of rotor units that are arranged in an axial direction and face the stator with an air gap therebetween. Each rotor unit consists of two rotor cores that are separated in the axial direction and a magnet sandwiched thereby and magnetized in the axial direction. Each rotor core has small rotor teeth around its outer surface. The rotor cores of each rotor unit are deviated by ½ pitch of the small rotor teeth, and the two rotor units are arranged to make the magnetic polarities of the small rotor teeth of the adjacent two rotor cores identical. A magnet thickness Tm and a rotor core thickness Tc satisfy 0.25?Tm/Tc?0.45.

Abstract: An serial axial fan unit includes a first axial fan arranged to rotate about a central axis, a flow control device connected to the first axial fan along the central axis, and a second axial fan connected to the flow control device along the central axis. The flow control device preferably includes a wind tunnel portion, a base portion, and a plurality of flow control vanes. A flow of air caused by rotation of first blades has a whirl velocity component in substantially the same direction as the rotation direction thereof. This whirl velocity component is converted to a velocity component in a direction parallel or substantially parallel to the central axis by interference of first stationary vanes. The above arrangement provides an improvement in air volume characteristics of a serial axial fan unit including two axial fans arranged in series.

Abstract: A motor driving circuit for full-wave single-phase driving a motor includes a position detection unit, a turn-on signal generation unit, and switching devices that define an H-bridge circuit. The turn-on signal generation unit includes a differential amplifier arranged to produce a trapezoid wave signal, and a square wave generation circuit arranged to produce a square wave signal, wherein the trapezoid and the square wave signals are respectively supplied to control terminals of lower switching devices in the H-bridge circuit. Further, one of the lower switching devices is turned on and off according to a voltage level of the square wave signal, and the remaining lower switching device is turned on and off when a voltage of the trapezoid wave signal becomes higher than an operation voltage of the remaining lower switching device, wherein a non-conducting interval is provided for the motor coil according to the operation voltage.

Abstract: A centrifugal fan includes a scroll casing having first and second flat base walls, and a circumferential side wall. An air inlet is formed on a center portion of the first base wall and an exhaust port is formed on the circumferential side wall. An airflow correction mechanism that forms smooth airflow when an impeller rotates is provided. The mechanism has an annular rib that is formed on the inside surface of the first base wall so as to be jutted to the side of the second base wall and to be concentric with the rotating shaft, and a recess portion that is formed on every blade of the impeller so that the annular rib is inserted therein with a predetermined gap. The annular rib and the recess portion are configured to change the direction of airflow directed to the air inlet back to a space between the blades.