Abstract: One aspect of the present invention relates to a process for preparing plastic lenses having a high-refractive index comprising forming a mixture containing one or more polyisocyanate compounds; one or more active hydrogen compounds selected from the group consisting of a polyol compound having no sulfur atom, a polyol compound having at least one sulfur atom, and a polythiol compound having at least one sulfur atom in addition to the sulfur atom contained in mercapto group and at least one internal releasing agent and then casting and polymerizing the mixture.

Abstract: A reproducing rate control apparatus for an optical disk includes a synchronizing clock generating unit which generates a synchronizing clock pulse with a phase locked to a phase of a digital reproduction signal. A signal processing unit generates a demodulated data signal from the digital reproduction signal in accordance with the synchronizing clock pulse, wherein the demodulated data signal is written to a memory in accordance with the synchronizing clock pulse, the demodulated data signal is read from the memory in accordance with a read reference clock pulse, and the read demodulated data signal is processed through an error correction so that a processed demodulated data signal is output. A frequency detecting unit detects whether the frequency of the synchronizing clock pulse is within a predetermined range of frequencies centered at a standard frequency.

Abstract: One aspect of the present invention relates to a process for preparing plastic lenses having a high-refractive index comprising forming a mixture containing one or more polyisocyanate compounds; one or more active hydrogen compounds selected from the group consisting of a polyol compound having no sulfur atom, a polyol compound having at least one sulfur atom, and a polythiol compound having at least one sulfur atom in addition to the sulfur atom contained in mercapto group and at least one internal releasing agent and then casting and polymerizing the mixture.

Abstract: A disk apparatus using a CLV method is provided in which disk apparatus a power consumption is reduced by providing a power save mode in which an operation of a head driving system is stopped during a standby state. The disk apparatus uses a constant linear velocity method by which method a recording/reproducing operation of information on a disk is performed while the disk is rotated at a variable speed so that the linear velocity of the head relative to the disk is maintained to be constant. A disk driving unit rotates the disk, and a head driving unit drives the head. A linear velocity controlling unit controls a rotational speed of the disk so that the linear velocity of the head relative to the disk is maintained to be constant. A constant rotational speed controlling unit rotates the disk at a constant rotational speed. A switching unit switches a control of the disk driving unit to be performed by either one of the linear velocity controlling unit and the constant rotational speed controlling unit.

Abstract: A system for infallibly positioning a transducer on Track Zero on a flexible magnetic disk in the face of possible sensing errors by an optical Track Zero sensor customarily build into a disk drive. The transducer has not been correctly recalibrated if it has been positioned, when the disk drive is powered on, on an invalid track existing, either virtually or actually, immediately radially outwardly of Track Zero and if the disk drive is connected to a host that commands recalibration merely by causing transducer travel radially outwardly of the disk. A recalibration control circuit is therefore provided which cancels the host command and which, instead, causes the transducer to travel a predetermined distance radially inwardly of the disk and then to travel radially outwardly until the Track Zero sensor indicates again that the transducer is positioned on Track Zero.

Abstract: An optical disk device generating reproduced data based on a reproduced digital signal which is derived by tracking a track on an optical disk with an optical pickup is shown. A bit-frequency-information generation unit measures a bit frequency of the reproduced digital signal after transition of the optical pickup in a seek operation, and generates measured-bit-frequency information which indicates a measured bit frequency measured thereby. In a bit-frequency setting unit, if there is a difference between the measured bit frequency and a specified bit frequency, the measured-bit-frequency information is corrected so as to adjust the bit frequency of the reproduced digital signal to the specified bit frequency by a given amount of correction, and is produced as setting-bit-frequency information.

Abstract: An optical disk reproducing apparatus uses a spindle motor having a low torque to reduced power consumption and manufacturing cost while maintaining a low error rate for reproduced data. The spindle motor is rotated at a constant rotational speed under a CAV control when a pick-up is moved. The rotational speed of the spindle motor is switched to a reference linear speed under a CLV control when a reproducing operation is performed. The reference linear speed is established for each of the zones of a recording area of an optical disk. The reference linear speed is determined by generating a zone clock set for each of the zones. A frequency error signal is generated by comparing the zone clock with the reproduction data so as to maintain the spindle motor at the reference linear speed determined by the zone clock.

Abstract: A microcomputer system having a flexible magnetic disk drive and a controller therefor, with the disk drive including a stepper motor for incrementally moving a transducer from track to track on a rotating magnetic disk, and a clock which is inherently unstable in operation during a predefinable startup period thereof after being powered on. In order to enable the disk drive to internally generate stepping pulses for driving the stepper motor at twice as high a rate as by external stepping pulses from the controller without being affected by unstable clock pulses during the startup period of the clock, the controller supplies external stepping pulses to the disk drive after imparting a predetermined delay, longer than the startup period of the clock, to each series of external stepping pulses with respect to the moment a power save signal, also supplied from the controller to the disk drive, indicates that the clock and other power consuming parts of the disk drive be powered.

Abstract: A power saving system for a flexible magnetic disk drive utilizes a power save signal supplied from a host system. When the power save signal indicates that the disk drive is standing by, a power saving circuit holds unpowered desired components of the disk drive such as a disk drive motor circuit, stepper motor circuit, read/write circuit and sensor circuits. The power saving circuit is constructed to permit the transducer to be recalibrated on a reference track on the disk only when the disk drive is turned on, but to inhibit such recalibration when the power save signal indicates the end of standby, thereby avoiding waste of power.

Abstract: A flexible magnetic disk drive incorporates a system for reducing the power consumption of a disk sensor according to a power save signal which is supplied from a host system and which indicates whether the disk drive is active or inactive. The disk sensor has a switch connected in series with a resistor, the sensor switch being opened or closed depending upon whether a flexible magnetic disk cartridge is loaded in or unloaded from the disk drive. For powering the disk sensor at least when the disk drive is active, and for unpowering the same when the disk cartridge is unloaded while the disk drive is inactive, an OR gate is provided which has its output grounded via the sensor switch and the resistor, one of its two inputs connected to the power save signal line, and the other input to a circuit point between sensor switch and resistor.

Abstract: A flexible magnetic disk drive is disclosed which has a data transducer mounted to a pivotal support beam for movement into and out of data transfer contact with the disk. When the transducer is retracted away from the disk, the support beam butts on the top plate of the disk drive casing for the reduction of the thickness of the disk drive, that is, its dimension in a direction perpendicular to the plane of the disk. A stepper motor is provided for moving the transducer across data tracks on the disk in response to external stepping pulses from a host system and to internal stepping pulses for recalibration. The application of such stepping pulses to a stepper motor control circuit is prevented when the disk is not loaded in the disk drive, in order to avoid the movement of the support beam in sliding contact with the top plate.

Abstract: A flexible magnetic disk drive is disclosed which operates under the control of a host system. A CMOS inverter is employed as a power saving switch, holding a file protect sensor energized only when the standard "drive select" signal from the host commands operation of the disk drive. Another CMOS inverter is provided for two disk capacity a sensors which provide signals indicative of the data storage capacity of the loaded disk cartridge. The disk capacity sensors are energized only when the drive select signal commands operation of the disk drive and when the standard "motor on" signal dictates rotation of a disk drive motor.

Abstract: A magnetic disk drive is disclosed which has a tunnel erase head assembly comprising a read/write head for writing and reading data on a magnetic disk, and a pair of tunnel erase heads for trimming a pair of opposite marginal edges of the record track being formed by the read/write head, with the consequent formation of spaces intervening between the record tracks. The spaces created on the same disk by different disk drives may be of one polarity of magnetization or the other, with the possibility of noise production due to an abrupt change in the polarity of magnetization as the read/write head scans any of the spaces as a result of mistracking. For the reduction of such noise the coil of the tunnel erase heads is connected to an erase current source via a circuit whereby the erase current is made to have a staircase or ramp rise and fall.

Abstract: A floppy disk drive is disclosed which is for use with a host system capable of connecting its own power supply to the disk drive when its operation is needed, and disconnecting the power supply from the disk drive when its operation is not needed. The disk drive includes a stepper motor for moving a data transducer from track to track on a rotating magnetic disk, and a track counter for ascertaining the radial position of the transducer on the disk by counting the stepping pulses fed from the host system to a stepper motor control circuit. In order to maintain the count of the track counter despite power suspension, the track counter is connected to a supply terminal of the disk drive via a reverse blocking diode, and a capacitor is connected between the diode and ground. The track counter is therefore fed from the capacitor when the disk drive is disconnected from the power supply of the host system.

Abstract: A floppy disk drive controller has a control part which performs a plurality of kinds of controls by means of outputting control information appropriate to each kind of control, and a memory part in which information which selects a predetermined kind of control from among the plurality of kinds of controls is pre-stored, the control part outputting the control information corresponding to the predetermined kind of control which is selected based on the information from the memory part.

Abstract: A disk drive connected to a host computer compatible with a plurality of computer hardware types can automatically transmit one desired control signal to the host computer, the desired control signal corresponding to a computer hardware type which is being used for the host computer. The disk drive may use a signal transmitted from the host computer which represents a storage capacity of a disk used for the disk drive.

Abstract: A flexible magnetic disk drive is disclosed which has a stepper motor coupled to a data transducer via a steel belt motion translating mechanism for moving the transducer from track to track on the rotating disk in response to stepping pulses and a stepping direction signal from an external host system. In order to save power, the stepper motor is held deenergized while the disk drive motor is out of rotation, with the consequent possibility that the transducer may be displaced from the required track position on the disk while the stepper motor is held deenergized. Therefore, in order to always memorize the latest of the successive destination tracks commanded by the host system, a forward/backward counter is provided which counts the external stepping pulses in either direction depending upon the binary state of the external stepping direction signal.

Abstract: A disc apparatus includes a drive mechanism rotatively driving a disc recording medium and having a motor and a chucking mechanism provided on a shaft of the motor, a head reading out information from the disc recording medium, a disc loading detector for outputting a loading detection signal when the disc recording medium has been loaded into the disc apparatus, a chucking control circuit outputting a motor rotation control signal for driving the motor during a chucking operation by the chucking mechanism, a motor drive control circuit driving the motor when at least one of a motor rotation control signal from the chucking control circuit and from an external information processing apparatus controlling the disc apparatus are supplied, an information output circuit supplying information obtained from the head to the external information processing apparatus during the motor is rotated on basis of the motor rotation signal, and an output prohibit circuit prohibiting the supply of information from the informat

Abstract: The present invention relates to a process for producing a plastic lens having a high refractive index and profile regularity comprising forming a mixture of one or more of sulfur-containing aromatic polyisocyanate compounds, one or more of active hydrogen compounds selected from the group consisting of polyol compounds and polythiol compounds, and at least one internal mold releasing agent, and subjecting the resulting mixture to casting polymerization, and a plastic lens obtained according to the process.

Abstract: A 3,4-cis isomer of 4-ethyl-1-(substituted phenyl)-3-substituted phenyl)pyrrolidin-2-one, when reacted with a base, can be effectively convered into a 3,4-trans isomer thereof which has a high herbicidal activity useful as an effective ingredient for a herbicidal composition. Furthermore, 3,4-trans-4-ethyl-1-(substituted phenyl)-3-(substituted phenyl)pyrrolidin-2-one compounds represented by the formula (III) ##STR1## (wherein R.sup.2 is an isopropyl group, and X is a fluorine atom, chlorine atom or bromine atom substituted at the 3-position, or fluorine atoms substituted at the 3- and 4-positions or the 3- and 5-positions) have an extremely excellent activity particularly as a herbicidally active ingredient of the herbicidal composition for rice paddy fields.