Abstract: 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.

Abstract: 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.

Abstract: A claw pole type synchronous motor has two cylindrical stator assembles arranged back-to-back and a magnetized rotor provided coaxially with the stator assemblies. The rotor has a length larger than the total thickness of the stator assemblies and always covers the inner peripheral surfaces of the stator assemblies so as to reduce vibration due to axial movements of the rotor with respect to the stator assemblies. The motor also has an electrical phase angle defined between the center lines of the corresponding claw poles of the adjacent stator assemblies made equal to the theoretical electrical phase angle minus an electrical angel within a range more than 0.degree. and less than 10.degree..

Abstract: 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.

Abstract: A motor structure including a rotor 1 having a permanent magnet 10 where north poles and south poles are alternately disposed in a moving direction of the rotor, a stator 5a including at least two stator yokes having stator pole teeth 3a, 4a respectively which face to the permanent magnet at a distance and are respectively positioned side by side in the moving direction to bear north poles or south poles respectively due to an electric current flowing through a coil 2a to thereby form at least one phase, wherein the stator pole teeth 3a, 4a are different from each other with respect to an effective area through which magnetic flux passes, whereby high harmonic wave phases generated from the pole teeth 3a, 4a are different from each other by 180 degrees in electric angle to thereby be canceled mutually, therefore an induced electromotive force wave containing hardly high harmonic wave is obtained to thereby reduce a motor vibration.

Abstract: This invention is to provide a low-cost structure that a cogging torque and a torque ripple are small and a stable rotation is provided in a radial gap type motor.A portion that stator pole teeth 37 to become interpoles are provided between stator poles 38 and a plurality of stator pole teeth 37 are not continuously provided between the partial stator poles 38 is provided. As a result, in this invention, a magnetic attraction force between the stator pole teeth 38 and the rotating pole 9 of a rotor 6 is stronger in the case that the pole teeth 37 are provided than in the case that the pole teeth 37 are not provided.Accordingly, the rotational shaft 12 of the rotor 6 is supported at three points of points P, Q and R of the bearing cylinder 4, and a rotary force is received at the point P as a center. As a consequence, the rotational shaft 12 is rotated with less contact friction with the bearing cylinder 4.

Abstract: To reduce as much as possible the motor vibration due to the effect of harmonic components contained in the induced electromotive force waveform induced in the armature coil. In a motor structure, the pole tooth shapes of one pole tooth and the corresponding pole tooth thereto constituting one phase are made different from each other by changing their areas or amounts of skew, whereby the third harmonics caused by variations in the magnetic fluxes interlinking with these pole teeth are caused to cancel each other. Thus, the rotational vibration which has hitherto been a problem can be reduced and, further, the accuracy of the rotor movement can be improved without lowering the dynamic torque characteristic of the motor.

Abstract: 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

Abstract: In order to raise the drive efficiency of a spindle motor that drives a recording disk for information recording and hence to achieve power saving/lowering of noise level of the information recording device as a whole, in an information recording device wherein a synchronous motor is employed as the spindle motor that drives the recording disk for information recording, and wherein the head is accessed for purposes of reading or writing information at a designated position on the recording disk, with change in mechanical output of this spindle motor, the mechanical output value sought for the spindle motor is found from the head position on the recording disk before and after access, and the thus-found mechanical output value is used to adjust the electrical input to the spindle motor.

Abstract: 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.

Abstract: There is provided a storage device whose cost is greatly reduced by employing a low-cost claw-pole two-phase synchronous motor as a spindle motor in which the rotation nonuniformity and vertical fluctuation of its shaft are suppressed while suppressing the leakage magnetic flux, by employing an open-loop scheme for motor control, and by mounting a drive circuit on the side of a control LSI for controlling the device to omit a motor control drive circuit (driving IC). The number of basic steps of the claw-pole two-phase synchronous motor is set to 48 steps or more. Stator pole teeth between both sub-assemblies are located within the range of 90.degree..+-.5.degree. in electrical angle. One end surface of a rotor having a field magnet is subjected to index magnetization also serving as rotor chuck magnetization. A magnetic shield plate is arranged on the surface of the rotor opposite to the magnetic head.

Abstract: A motor structure having a stator core including an armature coil wound on stator plates and arranged in parallel on the surface of the motor mounting plate and a bearing mechanism for supporting a rotor rotatably provided at the center of the stator oppositely to the stator wherein the stator core is coupled by an integrally molded form with a housing for holding the bearing mechanism

Abstract: This invention is to provide a stator structure for a rotary electric machine comprising poles of an armature core made of soft magnetic material and bobbins wound with coils at the respective poles and inserted into the poles in which the bobbin wound with the coils are mounted at the stator poles without decreasing motor characteristics. The material of a collar part (auxiliary pole tooth or extrapolation pole tooth) of a bobbin opposed to a rotor is formed of resin filled with soft magnetic material to improve the characteristics of a rotary electric machine. It is also effective to form the end of the collar part of the bobbin of a ferromagnetic material. Since a magnetic flux is also passed through the auxiliary pole tooth or the extrapolation pole tooth provided at the bobbin, the magnetic reluctance of the magnetic path to the rotary pole can be reduced.

Abstract: A motor structure of a claw pole type two-phase synchronous motor has a stator including two armature coils held between corresponding pairs of stator yokes and superposed on one another, and a rotor coaxially mounted on the stator and having a rotary shaft around which the rotor rotates so that a part of the chassis of a memory apparatus forms one of the stator yokes.

Abstract: An index signal is used for assuring media for use in a floppy disk drive to be exchangeable with each other. While the signal is output once for each rotation of a spindle motor, since the signal generation is carried out in a non-contact manner with rotating members including the medium, a hole sensor or the like has been previously used. However, such a hole sensor is expensive and fragile under temperature and mechanical stress. A pulse generator has been proposed, in which the rotor magnet is provided with magnets having unequally allocated angles and disposed all along a circumference and a stator coil and is disposed so as to match with the rotor magnet to have a pulse generated once for each rotation. However, the generated signal has, been poor in its S/N characteristic. It is an object of the invention to overcome the difficulties and provide a pulse generator that is highly reliable and excellent in the S/N characteristic with the manner of allocation of angles for the rotor magnet improved.

Abstract: This invention provides a two-phase motor which is applicable to a field where high rotation precision is required as in an FDD spindle motor, which requires a low cost, and which can maintain stable characteristics free from magnetic balance fluctuation between the two phases due to assembly. This motor has a ferromagnetic stator having N stator salient poles and a rotor magnet having M poles. N and M are selected to be both even numbers so a relation N:M=2:2n-1 (n is a natural number) holds. The N stator salient poles are divided into first and second salient pole groups of N/2 stator salient poles on which windings are concentratedly wound. The stator salient poles belonging to the first and second salient pole groups are alternately arranged in the circumferential direction of the stator. The phases of the windings of the stator salient poles belonging to the first and second salient pole groups are sequentially opposite to each other in the circumferential direction in units of groups.

Abstract: A claw pole type synchronous motor has input frequency increasing portions in a form of notches or holes formed in portions of claw poles which have the lowest magnetic flux densities so that the motor operates in a range from a low frequency to a high frequency without lowering torques too much.

Abstract: In a two-phase, half-wave drive brushless motor or other dynamoelectric machine, a cogging torque reduction effect can be achieved without any reduction in motor output by reducing the number of auxiliary slots on the main pole surface or auxiliary pole surface and the number of winding slots provided between the main poles and the auxiliary poles.

Abstract: A two-phase unipolar drive type brushless DC motor has an armature including a stator yoke with salient poles around which coils are wound, and a rotor having a retainer with a rotor magnet which faces the armature at a predetermined small interval defined between the rotor magnet and the armature. The retainer is made of a polymeric material containing magnetic powder and formed integral with a rotor magnet. The rotor magnet is made of a highly efficient magnetic material or a rare earth magnetic material and consists of segment type permanent magnet pieces which are arranged circumferentially in the retainer. The motor is manufactured at a low cost and provides a stable magnetic wave form which can be used as a spindle motor in various kinds of memory apparatuses.

Abstract: A shield plate for preventing the leakage of a magnetic flux and for reducing acoustic/electromagnetic noise leaking out from the interior of the motor is arranged so as to cover the corresponding end surface of an armature. The inner diameter of the shield plate is made smaller than the outer diameter of a rotor in order to prevent the rotor from being detached from a stator assembly.