Abstract: A battery pack is detachably provided for a drive main body. When carrying, an interface card and a connector cable are detachably supported and fixed to the drive main body by a holder member, thereby packaging. A power source is supplied from an upper apparatus to a control IC circuit unit of a device via the interface card. Only when both of the power supply from the upper apparatus and the power supply from an external power source unit are detected, the power source from the external power source unit is supplied to a device circuit unit, thereby making the device circuit unit operative.

Abstract: A frequency synthesizer generates, through setting of a frequency control value, a reference clock having a frequency necessary to read data from a medium. When reading data from an arbitrary position on the medium, a setting control unit sets in the frequency synthesizer a frequency control value corresponding to the zone position, thereby allowing the frequency synthesizer to control a reference clock frequency, and sets in a single or a plurality of processing units other than the frequency synthesizer a predetermined control value corresponding to the read position on the medium. A settling wait processing unit calculates a settling time T1 required for a frequency of the frequency synthesizer to become stable and a setting processing time T2 necessary for the setting control of the other processing unit, and defines as a wait time Tw a difference (T1-T2) between the settling time T1 and the setting processing time T2, during which wait time Tw a migration to the subsequent processing is kept waiting.

Abstract: There is provided an optical storage device that can position a lens carriage and objective lens even when position sensors for the lens carriage and objective lens are excluded in an effort to make an optical disk unit thinner. In the optical storage device, immediately after an optical disk is loaded in a main body, the cutoff frequency of a filter lying on a path of a reproduction signal is temporarily changed to a lower frequency. A spacing of sectors of the optical disk is detected using a signal sent from the filter. A type of an optical storage medium and a position of a current reproduction track are detected on the basis of the detected sector spacing and data stored in a memory.

Abstract: A positioning control system for performing recording/reproducing operations by irradiating an optical beam to a predetermined position on an optical recording medium, includes a photo-detector and a servo-error signal generating circuit which can generate at least one servo-error signal in accordance with a difference between the detection currents.

Abstract: High-purity isochroman compounds can be obtained in high yields according to a simple and economical process for preparing isochroman compounds, comprising the step of adding an aquesous solution of formaldehyde having a concentration of 40 to 70 wt. % to a complex of an arylalkanol represented by the following general formula (II) with a Friedel-Crafts catalyst to cyclize the arylalkanol: ##STR1## wherein R.sub.1 and R.sub.2 each stands for a hydrogen atom, a lower alkyl group or a lower alkoxyl group, or alternatively R.sub.1 and R.sub.2 are respectively bonded to adjacent carbon atoms with mutual bonding of R.sub.1 and R.sub.2 together with the carbon atoms respectively bonded to R.sub.1 and R.sub.2 to form a benzene ring, a naphthalene ring, or a C.sub.5 or C.sub.6 cycloalkane or cycloalkene which may have 1 to 6 lower alkyl groups; and R.sub.3 stands for a hydrogen atom or a lower alkyl group.

Abstract: A positioning control system for performing recording/reproducing operations by irradiating an optical beam to a predetermined position on an optical recording medium, e.g., magneto-optical disk. The control system includes a photo-detector constituted by at least two-divisional units, and a servo-error signal generating circuit which can generate at least one servo-error signal in accordance with a difference between the detection currents. Preferably, the servo-error signal generating circuit includes at least one division circuit that has two pairs of transistors, two emitters in each pair of transistors being connected together into a common emitter, bias voltages of a direct current type being applied to the respective bases of transistors on one side, and the respective collectors of the transistors on one side being connected to a common connecting portion via resistors.

Abstract: To provide a simple process for economically preparing a dihydropyrane compound at a high productivity and a high reaction yield.To use a compound selected from the group consisting of a base and a compound (VIII) having a weaker coordination power to the Lewis acid than the aldehyde compound and having an activity to dissolve the Lewis acid, coordinated by the compound (VIII), in a solvent as a co-catalyst in reacting aldehyde with a diene compound in the presence of a Lewis acid to prepare a 5,6-dihydro-2H-pyrane compound represented by formula (III): ##STR1## in which R.sup.1 represents a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, aryl group which may be substituted with alkyl group, having 6 to 12 total carbon atoms; R.sup.2 and R.sup.3 represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.

Abstract: The object of the present invention resides in efficiently providing unsaturated alcohol from an .alpha.,.beta.-unsaturated aldehyde.The present invention provides a process for preparing unsaturated alcohol by selectively reducing the aldehyde group of an .alpha.,.beta.-unsaturated aldehyde in the presence of a primary or a secondary alcohol having 2 to 8 carbon atoms using an aluminum alcoholate to produce an unsaturated alcohol such as compounds represented by the formula (III). ##STR1## (wherein R represents an alkyl group having 1 to 3 carbon atoms) wherein the reaction is carried out with addition of a protonic acid.

Abstract: A positioning control system for performing recording/reproducing operations by irradiating an optical beam on a predetermined position on an optically recording medium includes a photo-detector constituted by at least two-divisional units and a servo-error signal generating circuit which can generate at least one servo-error signal in accordance with a difference between detection currents measured at the collectors of selected transistors in two pairs of transistors.

Abstract: A positioning control system for performing recording/reproducing operations by irradiating an optical beam to predertermined position on an optically recording medium, e.g., magneto-optical disk, includes a photo-detector constituted by at least two-divisional units; and a servo-error signal generating circuit which can generate at least one servo-error signal in accordance with a difference between the detection currents.

Abstract: Disclosed is an optical disk apparatus having a zero-cross signal generating unit for differentiating a reproduced signal read from an optical disk and outputting a zero-cross signal when the differentiated signal crosses the zero level, and a gate signal generating unit for generating a gate signal using the reproduced signal, wherein a data pulse is outputted when the zero-cross signal is generated while the gate signal is being produced. A clamping circuit clamps the peak of a reproduced signal from an optical disk, an amplitude comparator compares the amplitude of a clamped signal, which is outputted by the clamping circuit, with a reference voltage, and an AGC control unit controls the gain of a variable-gain amplifier by generating a control voltage signal in dependence upon an amplitude difference. The gate signal generating unit generates the gate signal upon comparing the clamped signal outputted by the clamping circuit with a prescribed signal level.

Abstract: A positioning control system for performing recording/reproducing operations by irradiating an optical beam to predetermined position on an optically recording medium, e,g., magneto-optical disk, includes a photo-detector constituted by at least two-divisional units; and a servo-error signal generating circuit which can generate at least one servo-error signal in accordance with a difference between the detection currents.

Abstract: A biological pure culture of a microorganism belonging to the genus Rhodococcus and being capable of oxidizing the allyl position of .alpha.-cedrene, a process for producing sec-cedrenol comprising contacting a microorganism belonging to the genus Rhodococcus with .alpha.-cedrene, and a process for producing cedrenone comprising oxidizing sec-cedrenol produced by a microorganism belonging to the genus Rhodococcus, are disclosed. According to the process of the present invention, sec-cedrenol can be produced efficiently within a short period of time and with high purity. In addition, the process of the present invention can produce cedrenone with a high yield in a large quantity within a short period of time.

Abstract: A laser diode having a cathode connected to the ground side of a positive power source and an anode connected to the plus voltage side of the power source through a control circuit. A maximum current to drive the laser diode is supplied to the laser diode by a disgorging type constant current source. In a reading mode operated at a frequency one or more digit higher than a frequency for writing data, a differential current between the write current and a read current is sucked from the disgorging type constant current source by a sucking type constant current source, thereby allowing the read current to flow into the diode. In a writing mode, a current switch connects the sucking type current source according to write data. The disgorging type current source and the sucking type current source are connected to a photodiode by a current switch. An APC responds to the photodiode which detects a read power, thereby reducing a laser fluctuation created from temperature change.

Abstract: A position control system for an information storage system, for example, an optical disc system, includes a stepping motor for moving a read-write head and a DC motor for moving a beam reflecting unit, such as an object lens mounted on the head. The position control system drives the stepping motor to compensate a positional error of the beam reflecting unit in a tracking mode after a seek without disturbing the movement of the beam reflecting unit. The position control system includes a master control unit operatively connected to a host controller, a stepping motor control unit, and a track servo control unit. The master control unit activates the stepping motor control unit for a seek operation upon receipt of a seek command from the host controller. The stepping motor control unit drives the stepping motor with a large drive current until the head moved by the stepping motor reaches a position adjacent to a target track on the recording medium.

Abstract: An optical disk access system capable of varying the focus position of a beam spot illuminating the optical disk. The focus position of the beam spot is varied in accordance with a mode of operation of the optical disk system. The various focus positions are automatically selected by the optical disk access system by intentionally vibrating the beam spot in a radial direction of the optical disk and detecting the amount of light reflected from the optical disk while varying a signal that changes the focus position of the beam spot. The optical disk system automatically selects a value of the signal determining the focus position of the beam spot that corresponds to maximum values derived from the light reflected from the optical disk.

Abstract: A toner for electrophotography produced by polymerizing a monomer dispersed by emulsification in the presence of a colorant and/or a magnetic powder, followed by coagulation is excellent in properties, particularly in cleaning properties, charge stability and caking resistance.

Abstract: A track access control system for a disk storage system having an eccentricity correction unit. The eccentricity correction unit includes an eccentricity detecting unit, an eccentricity data storage unit and an eccentricity compensation unit. The eccentricity data storage unit includes a memory, an address generating circuit, a filter and a comparator. The comparator and the filter function as delta modulation means to provide digital eccentricity data to be stored in the memory. The filter also outputs analog eccentricity data to be used for compensation of the eccentricity.

Abstract: A toner for electrophotography produced by polymerizing a monomer dispersed by emulsification in the presence of a colorant and/or a magnetic powder, followed by coagulation is excellent in properties, particularly in cleaning properties, charge stability and caking resistance.

Abstract: A tracking servo control system of an optical disk system produces a tracking control output signal for control of a tracking actuator which is adjusted to enable accurate positioning of a focussed light beam spot of the optical disk system at the center of a selected groove of a disk, for a variety of optical disks having various groove shapes. The output signal of a light receiver responsive to reflected image of the light beam spot focussed on the disk is processed to produce a tracking error signal:Y and a sum signal:X which are processed by a correction circuit for calculating the value: ##EQU1## where Z is a correction factor, the value of which is adjusted, to normalize the calculated value:E, in accordance with the peak detected value of E.