Abstract: A method and apparatus for packing a permanent magnet powder wherein a solenoid coil is provided near the opening of a cylindrical molding space of a mold in such a manner that the direction of the central axis of the solenoid coil substantially coincides with the central axis of the molding space, and an alternating current magnetic field is applied, so that a permanent magnet powder above the opening is packed into the molding space. A magnetic pole may be provided in the center of the solenoid coil. The method of the present invention can be applied to not only a powder for a sintered magnet but also a powder for a bonded magnet.

Abstract: The present invention provides a dielectric ceramic composition for use in a high-frequency range represented by the general formula (1-x)Ba.sub.1- y(Zn.sub.1/3, Ta.sub.2/3)O.sub.3 +xBa.sub.1-y ZrO.sub.3. In the formula, y is 0.004.ltoreq.y.ltoreq.0.013 and x is the amount of substitution of Ba.sub.1-y ZrO.sub.3 and 0<x.ltoreq.0.06. This composition is prepared by weighing raw materials so that the mixing ratio of Ba is slightly smaller than that of the stoichiometric composition, calcining the resultant mixture to prepare a calcination product, grinding the calcination product through only dry process without conducting wet pulverization, molding the resultant powder, and sintering the molded product at 1600.degree. to 1700.degree. C. for 1 to 10 hr.

Abstract: An optical head apparatus is adapted to write and read data onto and from an optical disk using an optical beam emitted from a light-emitting element. Such an optical head apparatus includes: a lens actuator having a lens casing for retaining an objective, magnetic circuits provided on two sides of the lens casing, a coil having a part placed in the gaps formed by the magnetic circuits; a focus detector having a detection lens assembly consisting of a plurality of lenses for correcting aberration, a divided photodetector for receiving a light beam which has been converged by being passed through the detection lens assembly, and a differential amplifier for taking out a differential output from the divided photodetector, the detection lens assembly, the divided photodetector, and the differential amplifier being disposed in the optical path of light reflecting from the optical disk.

Abstract: A rectified ac voltage which is not smoothed is compared with a reference voltage directly, and a pulse is generated when the instantaneous value of the rectified ac voltage exceeds the reference voltage. Based on the pulse generation, a judgement is performed on whether the ac voltage is reaching a predetermined value or not. These operations allow the abnormality of the ac voltage to be rapidly detected with improved accuracy.

Abstract: In an automatic voltage switching power source having a full-wave rectifier circuit and a voltage doubler circuit, a controller comprises a plurality of voltage level detectors which are associated with an input ac voltage and detect different voltages, and a switching signal generator which generates a delayed signal for switching between the full-wave rectifier and voltage doubler circuits based on the logical product of the outputs of the voltage level detectors, thereby preventing the electric circuit of the power source and the electric device to be supplied with the power from being damaged by excessively high voltages.

Abstract: An electronic circuit module having a magnetic base plate, a plurality of coils wound on the magnetic base plate, a circuit pattern formed on the surface of the magnetic base plate, a circuit component connected to the circuit pattern, and a plurality of lead pins mounted on the magnetic base plate for connecting external circuits. The magnetic base plate has projections along one side of it and the coils are wound on the projections.

Abstract: A noise filter for an electric wire of star-connected three-phase four-wire system, in which a neutral conductor has a sectional area which is larger than a sectional area of each of voltage conductors. Three voltage conductors are wound on a magnetic core that constitutes a closed magnetic path. The neutral conductor is coupled to the three voltage conductors via three respective capacitors.

Abstract: A magnetic drum and parts ancillary thereto are enclosed in a housing consisting of an upper casing and a lower casing to form a cassette-type magnetic drum unit for voice information system. The magnetic drum cassette is releasable from the system which includes a magnetic head for reproducing the voice information stored in the magnetic drum.

Abstract: A piezoelectric buzzer includes a tone generator formed by bonding, to a resilient thin plate, a piezoelectric element having deposited thereon thin film electrodes, and an oscillation circuit formed by electronic parts connected to the electrodes. A conductive carrying area of a predetermined pattern is formed on the upper surface of the piezoelectric element along nodal points of vibration of the tone generator, and the electronic parts are fixedly mounted on the carrying area to constitute the oscillation circuit.

Abstract: A low temperature sinterable oxide magnetic material prepared by adding 0.1 to 5% by weight of glass containing 3 to 50 mol % of Li.sub.2 O, 10 to 97 mol % of B.sub.2 O.sub.3 and 0 to 70 mol % of SiO.sub.2 to ferrite containing at least 0.5 mol % of Li.sub.2 O. Especially, when a glass containing 10-28 mol % of Li.sub.2 O, 34 to 66 mol % of B.sub.2 O.sub.3, and 15 to 45 mol % of SiO.sub.2 is used, the sintering temperature can be reduced to about 1,000.degree. C. or less.

Abstract: A method of producing a stator yoke of a motor such as an inner rotor type stepper motor, the yoke having a multiplicity of polar teeth. The method has the steps of forming an intermediate blank which has an outer cylindrical portion and an inner cylindrical portion projecting in the same direction, effecting a shearing on the outer peripheral surface of the inner cylindrical portion to cut out a multiplicity of polar teeth arranged at a constant pitch, and effecting a punching to deepen and widen portions between the bases of adjacent polar teeth.

Abstract: A piezoelectric audible sound generator having a feedback type piezoelectric transducer, an amplifier, and a phase compensator for adjusting the phase shift due to the combination of a bias resistance of the amplifier and equivalent capacitance of the piezoelectric transducer.

Abstract: A new method for preparation of Mn-Zn or Ni-Zn type ferrite single crystals. The ferrite materials are provided in a lower portion of a crucible and completely dissolved. The crucible is moved within a predetermined atmosphere of temperature gradient. A solid which is equilibrium in composition to the ferrite materials is supplied into the crucible while the dissolved ferrite materials are crystallizing from the lower extremity while a liquid-phase zone is maintained constant in depth. Ferrite single crystals of at least about 800 mm in length are grown which are homogeneous in composition throughout their length.

Abstract: A magnetic drum/head system for selectively reproducing voice information recorded on the magnetic drum. The magnetic drum has a recording zone in which predetermined voice information is recorded in each track thereof and a non-recording zone between a starting end of the recording zone and a terminating end of the same. In case of a track selection, the magnetic drum is held still so that the non-recording zone is in a confronting relation to the magnetic head, and the magnetic head is driven to move along the non-recording zone to the selected track. The magnetic drum is then rotated to reproduce the selected voice information.

Abstract: There are provided a method of and an apparatus for controlling a pulse controlled brushless motor to immediately pull-in the motor to a predetermined rotational speed. The method has the steps of encoding rotational condition of a rotor into an electric signal, detecting the encoded signal to determine whether the rotor is in rotation or not, synchronizing a signal of a pull-in pulse rate with a clock pulse when the rotor is not in rotation and synchronizing the encoded signal with the clock pulse when the rotor is in rotation to form an input pulse train. The input pulse train is supplied to a peripheral circuit to excite the motor.

Abstract: An H-type ceramic resonator having two resonating leaves, a connecting leaf for bridging the two resonating leaves to form an H-shape, and electrodes disposed on at least both surfaces of the resonating leaves. The resonator has a dimensional relationship which falls within the following equities:B.sub.2 /B.sub.3 =4 to 6,B.sub.1 /B.sub.3 =2 to 4, andL/B.sub.1 =5 to 6wherein L is a length of each of the resonating leaves, B.sub.1 is a width of each of the resonating leaves, B.sub.2 is a distance between the two resonating leaves, and B.sub.3 is a width of the connecting leaf.

Abstract: A brushless motor actuated by a predetermined frequency and driven at constant speed with less wow and flutter component in accordance with a pulse signal of the frequency applied. The motor has a rotor enclosed in a stator, the latter having driving windings. The rotor includes a rotor shaft and a flywheel connected to the shaft. The flywheel is housed in a motor case.

Abstract: A process for producing Ni-Mn-Zn ferrite single crystal for high frequency wherein a sample comprising 10-30 molar percent of NiO, 1.8-12 molar percent of MnO, 15-35 molar percent of ZnO and 49-53 molar percent of Fe.sub.2 O.sub.3 is melted and subjected to growing into a crystal under an oxygen partial pressure of below about 100 Kg/cm.sup.2.

Abstract: In a gasket of a cell comprising a marginal portion, an annular center portion and an intermediate portion integrally formed with each other, the intermediate portion of the gasket has an inwardly projecting annular thin wall surrounding the annular center portion with an annular space therebetween. The annular thin wall has, generally, an inverted frusto-conical shape and is provided at the outer surface thereof with an annular horizontal groove and a vertical groove intersecting with each other.

Abstract: A sealing gasket of a cell comprises a circumferential marginal portion constricted between a metal casing and a terminal plate, a center collar through which a collector metal rod penetrates, and an intermediate portion integrally molded with the marginal portion and the center collar and having a thin wall portion tearable by a stretching force applied thereto. The center collar of the gasket is normally separated from the terminal plate but is movable toward the terminal plate by sliding on the collector metal rod in the event that the internal gas pressure within the cell is abnormally developed, whereby the thin wall portion of the gasket is stretched and torn to release the gas.