Matsushita Electric Industrial Co., Ltd.

Fujio Nakagawa

Masami Wada

Yoshihisa Katoh

Yasuo Sasaki

A thinned DC brushless motor (50) has a base plate 52 of magnetic material, a rotatable shaft (58) supported perpendicular to the base plate, an annular hub (68) coaxially fixed on the shaft, a stator (60) fixed on the base plate, and a rotor (70) coaxially fixed on the shaft through the annular hub. The rotor (70) includes an first wall portion (72) extended radially from the shaft above the stator and parallel to the base plate and a second wall portion (74) extended from a peripheral edge of the circular potion towards the base plate to enclose the stator. An annular magnet (78) is fixed on an inner surface of the second wall of the rotor with leaving a small gap from a peripheral edge of the stator. The upper wall has a bent portion (80) extended outward away from the annular magnet in the vicinity of an inner edge of the annular magnet.

Thin DC brushless motor having an air gap formed therein

A spindle motor includes a printed wiring board. A stator is fixed to the printed wiring board. A housing is fixed to the printed wiring board. A bearing is provided on the housing. A rotor shaft is rotatably supported by the bearing. A hub base is mounted on the rotor shaft. A stator winding provided on the stator is bonded to the printed wiring board. The stator may have an inner circumferential portion formed with a plurality of grooves. In this case, it is preferable that the printed wiring board has a plurality of through holes at positions corresponding to positions of the grooves in the stator.

Spindle motor

In a method for manufacturing yokes (3, FIG. 1) to be used in a permanent magnet type stepping motor (10, FIG. 2), a surface-treated dead soft steel sheet such as nickel-plated steel sheet or aluminized steel sheet containing carbon in 0.01 wt. % or less is press-worked to form yoke (3) having plural pole teeth (3a, FIG. 1) on its inner periphery, and then the yoke is annealed in an inactive gas atmosphere in a temperature range of 750.degree.-820.degree. C. to remove residual stress, and permeability of the yoke is improved.

Growing community of inventors

Yonago, Japan

Fujio Nakagawa