Minebea Company, Limited

Yoshiyuki Aono

Yuzuru Suzuki

Sakae Fujitani

Masaki Kagawa

Kunitake Matsushita

Masato Hata

Masahisa Ezuka

Masahisa Etsuka

An iron core type cylindrical radial gap type motor structure, by having field magnetic poles generated by permanent magnets and, in opposition to these, salient poles generating a rotational magnetic field and arranged with their emission direction along the rotational axis, the shape of salient poles being approximately T-shaped in cross-section along the rotational axis direction, and I-shaped in cross-section at right angles to the rotational axis direction, the upper end of said T-shaped opposing the axial direction of the rotor magnets and the lower end being mechanically coupled and fixed to the stator ring, thus constructing the magnetic circuit of the armature, and where the relationship between the length L,of the said salient pole in the axial direction opposed to the field magnetic pole, and the length L,in the axial direction of the coil core section about which the coil is wrapped, satisfies the conditions 0.3*L,&lE;L,&lE;0.6*L,, and, furthermore, where the relationship between the thickness A,of the said salient pole in the circumferential direction, and the pitch P of the field magnetic pole, satisfies the conditions 0.4*P&lE;A,&lE;0.8*P.

Compact cylindrical radial gap type motor

A motor structure having an armature yoke 1 including a cylindrical portion and a plurality of salient poles 20 formed in the radial direction on the circumference of one end of the cylindrical portion, characterized by having a stator coil 5 formed by a concentrated winding provided around a salient pole portion 20', which is formed by joining the salient poles 20 of two armature yokes 1 together, and a motor structure characterized by having the above described structure and further having a salient pole piece 11 disposed on the front end of the salient pole portion in confronting relationship with a rotor magnet 2.

Radial gap type cylindrical motor

A method for driving a recording disc applies a DC excitation hold so that a rotor portion is stopped. Thereafter, a DC excitation frequency is gradually increased from a low frequency to a rated frequency and synchronizes with the rated revolution.

Driving method for a stepping motor

There is disclosed a synchronous motor drive in which in a record disc drive of an information recording device a quantity of generated excitation noise is reduced to a small level to which a reading/writing signal is not influenced and a substantial motor generation torque is prevented from lowering. An absolute value of a maximum voltage gradient of a coil excitation voltage waveform is set to a certain value or less. The waveform alternates at a synchronous frequency which is determined by the number of poles of a rotating magnetic field produced in an air gap by a stator winding and the number of revolutions.

Motor drive method and drive circuit

Salient poles made from soft magnetic steel plates have tip sections of approximately the same length as a rotor magnet. The salient poles are constructed with laminations in the circumferential direction, with axial dimensions adjusted with respect to the circumferential dimensions determined by the constraints of the winding to allow winding sections with a minimum required cross-sectional area so that magnetic saturation does not occur. These winding sections are inserted into coils wound with magnet wire, and press fitted into the stator which makes the magnetic circuit with the salient poles and forms the armature.

Cylindrical radial gap type motor structure

The invention is related to a stepping motor drive and a driving method thereof and presents a technology to constantly monitor the phenomenon of step out during the operation of the motor and automatically bring into action a restarting circuit when a step out occurs so that said motor having stepped out may be able to automatically restart, wherein the stepping motor drive is provided with a starting instruction designed to start/stop the stepping motor, a speed sensor or an index sensor designed to detect the rotation speed of said motor, means to detect the rotation speed of said motor from the output of said speed sensor, a rotation speed detection means by detecting the difference of rotation speed with the rated rotation speed, a speed judgment means designed to output signals when the rotation speed of said motor has fallen below the set reference speed, and a restarting pattern generating means designed to automatically increase gradually frequency for a prescribed time from the pull-in frequency of said motor to the desired frequency.

Stepping motor drive and a method of driving same

An information recording device is provided, whereby an inexpensive stepping motor is used to drive a recording disk for recording information, the disk being driven under open-loop control by means of inexpensive digital circuit technology, without employing rotor position detectors or a speed detector, and the rotational accuracy of the recording disk is raised to a level suitable for application, without increasing cost, by constituting the aforementioned step operation (having poor rotational accuracy) inherent in the stepping motor such that certain relationships are formed between the structural parameters of the information recording device and the structural parameters of the motor. In a stepping motor, electrical energy is supplied by switching excitation at a timing synchronized to an input clock, regardless of the load. When this electrical energy is converted to mechanical energy, the moment of inertia of the rotating portion is exploited to a maximum in order to produce smooth rotation.

Growing community of inventors

Shizuoka-ken, Japan

Yoshiyuki Aono