Abstract: An optical semiconductor device used for optical information processing, such as writing information into and reading information from an optical disk. The optical semiconductor device includes a Si substrate, a light emitting element, and a reflector for reflecting light emitted from the light emitting element in a direction perpendicular to the mounting surface of the Si substrate. The reflector has a reflecting surface inclined by 45.degree. from a bottom face and formed by etching a single crystal of Si.

Abstract: A magnetic head driving device is disclosed. The device includes an inductor for generating a magnetic field, the inductor having a pair of terminals. The device has a first auxiliary coil for storing electromagnetic energy, the first auxiliary coil being connected to one of the terminals of the inductor at a first node, second auxiliary coil for storing electromagnetic energy, the second auxiliary coil being connected to the other terminal of the inductor at a second node, first main switch connected to the first node, second main switch connected to the second node, and control circuit for receiving a first signal indicating generation of a magnetic field by the inductor and a second signal indicating the direction of a magnetic field generated by the inductor and for outputting the second signal for a predetermined period of time in accordance with the first signal to alternately turn on or off the first main switch and the second main switch.

Abstract: In a magnetic head driving circuit, switching devices are turned on/off in response to a recording signal, thereby inverting a drive current to be applied from direct current power sources to a magnetic head coil. Switching devices to be switched in connection with on/off of the switching devices are connected in parallel with dummy loads connected to the direct current power sources in series. In response to the switching of the switching devices, the magnetic head coil and the dummy load alternately function as a load of each auxiliary coil. Impedances of the dummy loads are set to be equal to the impedance of the magnetic head coil, thereby making the total load of each of the auxiliary coils fixed at any time. Since a balance can be established between a value of a drive current in one direction and that of a drive current in the opposite direction, it is possible to reduce jitter of a recording mark and enable the drive current to suddenly rise and fall.

Abstract: A magnetic head driving device with two inductors sharing a common magnetic core is disclosed. The device includes an inductor for generating a magnetic field, the inductor having a pair of terminals. The device has a first auxiliary coil for storing electromagnetic energy, the first auxiliary coil being connected to one of the terminals of the inductor at a first node, second auxiliary coil for storing electromagnetic energy, the second auxiliary coil being connected to the other terminal of the inductor at a second node, first main switch connected to the first node, second main switch connected to the second node, and control circuit for receiving a first signal indicating generation of a magnetic field by the inductor and a second signal indicating the direction of a magnetic field generated by the inductor and for outputting the second signal for a predetermined period of time in accordance with the first signal to alternately turn on or off the first main switch and the second main switch.

Abstract: An external magnetic field generation apparatus is used for a recording and reproduction apparatus which records information on a magneto-optical recording medium based on the magnetic field modulation system and the light modulation system, and applies a magnetic field to the portion of the magneto-optical recording medium where the light beam is projected. The apparatus has the first electro-magnet, used for the magnetic field modulation system, for generating an a.c. magnetic field which is reversed at a high speed. The apparatus has the second electro-magnet, used for the light modulation system, for generating a strong d.c. magnetic field such that power consumption coincides with that of the first electro-magnet.The second electro-magnet is integral with the first electro-magnet. The apparatus has a driver for selecting one of the electro-magnets in response to a switching signal, and the driver supplies power to the selected electro-magnet.

Abstract: A recording method for a magneto-optic memory medium of exchange-coupled type having a recording layer of a low Curie point and high coercive force and a reading layer of a high Curie point and low coercive force, which comprises the steps of: applying a magnetic field to the magneto-optic memory medium to develop a predetermined data in the reading layer, and then applying both an optical beam and a magnetic field to the magneto-optic memory medium for writing the predetermined data in the recording layer, and simultaneously verifying the data upon the writing on the basis of a Kerr effect of the optical beam caused by the reading layer.

Abstract: A dust detector in a vacuum cleaner includes a light-emitting element exposed into a dust suction passage for emitting a light beam into the dust passage, and a light-detecting element exposed into the dust suction passage for detecting the light beam emitted from the light-emitting element. A detector unit detects the amount of dust flowing through the dust suction passage based on the intensity of the light beam transmitted from the light-emitting element across the dust suction passage to the light-detecting element. The light-emitting element and the light-detecting element are covered respectively by a pair of light-transmissive covers having respective end faces exposed into the dust suction passage and lying flush with an inner wall surface of the dust suction passage.

Abstract: A process for preparing an orientation film for liquid crystals which comprises forming a base layer of a thermoplastic or non-thermoplastic resin to be used for the orientation film, on a substrate for liquid crystal display, and rubbing the base layer under heating at a temperature not lower than 50.degree. C. but below the melting temperature of decomposition temperature of the resin.

Abstract: This present invention is characterized in that a titanium material on an .alpha. or (.alpha.+.beta.) titanium alloy material hydrogenated in an amount of 0.02 to 2% by weight of hydrogen is heated to a temperature above the .beta. transformation point and below 1100.degree. C., is hot worked in that temperature range at a reduction of 30% or more, the hot working is terminated in a .beta. single phase temperature region, and cooling to 400.degree. C. or less, and annealing in vacuum are then carried out, whereby titanium and titanium alloy materials having a fine acicular microstructure are obtained.