Abstract: Recording of preformat information is accomplished by magnetic transfer to a perpendicular magnetic recording medium with a higher density. The method includes: (1) an initialization step, in which a magnetic field is applied to the magnetic recording medium in the direction perpendicular to the medium surface and direction of magnetization of the whole surface of the magnetic recording medium is aligned to one direction perpendicular to the medium surface, and (2) a magnetic transfer step, in which a magnetic field in the longitudinal direction is applied to both a master disk carrying preformat information and the magnetic recording medium with the master disk in close contact with or in proximity to one or both surfaces of the magnetic recording medium.

Abstract: Automatic-signal-selecting is provided for controlling which output is supplied from a switch, i.e., a digital signal or an analog signal. The control is carried out based on information selected by manual-signal-selecting and information judged by copyright-information-judging. This structure allows a recording and reproducing apparatus to record the content-prohibited from being recorded in a digital form according to copyright information-in an analog form.

Abstract: A circuit for use in a phase lock loop including a first phase detector to detect a first phase error between input signals, the first phase detector obtaining the first phase error during a first time period, a second phase detector to detect a second phase error between the input signals, the second phase detector obtaining the second phase error during a second time period, the second time period being longer than the first time period, and a compensation circuit to compensate the first phase error with a portion of the second phase error signal.

Abstract: A method and circuit for selectively timing amplifier stages of a multi-stage reader amplifier for a hard disk drive system. The reader amplifier includes a first stage, second stage and third stage coupled in series. The method includes the steps of powering the first stage, delaying the enabling of the second stage, and delaying the enabling of the third stage, in order to reduce excursions on the third stage output signal. The circuit includes a logic circuit for successively enabling the second and third amplifier stages.

Abstract: A method and apparatus for obtaining optimum parameter values for a read channel employed in a disc drive storage system are provided in which data having a known pattern is written on a disc surface of the disc drive storage system. The data written on the disc surface is then read to obtain a readback signal. The readback signal is passed through the read channel. A readback signal response is obtained at an output test point of the read channel. The readback signal response at the output test point is compared with a target response of the read channel at the output test point. The comparison is carried out using frequency spectral analysis. At least one parameter of the read channel is adjusted if the readback signal response substantially differs from the target response.

Abstract: Here is disclosed an information recording and reproducing apparatus comprising a multi-phase quadrature angular modulator for subjecting a signal to be written on a recording medium to multi-phase quadrature angular modulation to generate a modulated signal expressing information in phase difference and frequency difference, a quantizer for generating a discrete signal by making discrete the amplitude of the modulated signal generated by the quadrature angular modulator with reference to a certain level, a write head for writing the output signal of the quantizer onto the recording medium, a read head for reading information written on the recording medium, a read compensate circuit for compensating the phase and amplitude of a signal readout of the read head, and a multi-phase quadrature angular demodulator for demodulating a signal supplied from the read compensate circuit by subjecting it to multi-phase quadrature angular demodulation.

Abstract: A differential circuit to read differential data from a disk by a current bias on a plurality of read heads includes a read circuit to read the differential data from the disk by maintaining the current bias. The current is below a maximum current of a read head having the lowest maximum voltage of said plurality of read heads.

Abstract: A data detecting method and its apparatus for equalizing an input signal reproduced from magnetic recording media by partial response by employing at least one of partial response class 4 (PR4) and extended partial response class 4 (EPR4), and decoding the input signal. The input signal is equalized by PR4, and a first equalized signal is obtained. First decoded data is obtained from the first equalized signal. The input signal is equalized by EPR4, and a second equalized signal is obtained. Second decoded data is obtained from the second equalized signal. From the first equalized signal and second equalized signal, the signal condition of the input signal is judged, and the optimum data detecting method is discriminated. Thus, either the first decoded data or second decoded data is selected as detected data.

Abstract: It is an object of the present invention to provide an optical recording medium having a new information recording part and an entertainment system employing it. According to an optical recording medium of the present invention, a new information recording part (210) is formed on parts other than the information recordable part (200O, 200D, 200I), and information can be written, read, and erased.

Abstract: A hard disk is provided with tools for limiting the duty cycle (a group of variations of load with time). The write current is controlled by, e.g., limiting the duration of a given write cycle. The write cycle may involve writing data continuously along adjacent portions of the disk media (e.g., writing of data in adjacent segments of a track in the outer diameter (OD) region of a platter), with an intermittent duty write current.

Abstract: A method of preprocessing low frequency components of a perpendicular read-back signal in a data storage system in order to reduce low frequency noise includes introducing a dominant known perturbation, to the perpendicular read-back signal, which masks the effects of other low frequency noise sources and leaves the read-back signal with one dominant low frequency noise component. The method then further includes removing the dominant known perturbation from the read-back signal to recover low frequency portions of the read-back signal in order to determine values of bits read from a storage medium. A perpendicular recording data storage system configured to implement the method is also disclosed.

Abstract: Apparatus and method for transferring data in a disc drive data handling system. A read/write head having separate write and read elements is used to write data to and transduce data from a disc recording surface. A preamplifier driver circuit applies write currents to the write element to write data to the recording surface and to apply a first read bias signal of selected, nonzero magnitude to the read element to transduce data from the recording surface. In response to the assertion of a write gate signal, the preamplifier driver circuit generates a second read bias signal of selected, nonzero magnitude and applies the second read bias signal to the read element while applying the write currents to the write element. This reduces the potential for damage to the read element due to cross-talk noise induced in the read bias signal from magnetic coupling between the read and write elements.

Abstract: A magnetic recording and reproducing head which includes a magnetic sensor, and a flux guide for introducing a magnetic flux into the magnetic sensor. At least a portion of the flux guide is constituted by a material which permits the magnetic flux to pass therethrough at a temperature of not lower than a predetermined temperature Tp, but not permit the magnetic flux to pass therethrough at a temperature of lower than Tp. Light is irradiated to only a portion of the flux guide to cause the temperature of the irradiated portion to rise up to Tp or more, thereby permitting a magnetic flux to pass only through the irradiated portion.

Abstract: A method and system for reproducing digital data read from a storage device. A second-order differentiation of a digital signal representing the digital data is calculated to control an automatic gain control (AGC) and phase lock loop (PLL) to rapidly correct amplitude and frequency offset of the digital signal being read from the storage device.

Abstract: The invention may be embodied in a disk drive for use in a mobile device. The mobile device may be a hand held computing device such as a personal digital assistant (PDA) or a mobile terminal such as a cellular telephone. The mobile device includes a host processor for accessing data on the disk drive. The disk drive has a rotating disk media and a moveable read/write head disposed over the disk media. The disk media is divided into a first data storage zone and a second data storage zone. The data storage zones are radially disposed in discrete areas of the disk media and each zone has a plurality of tracks for storing data. The mobile device may write data to the first data storage zone when the mobile device is in a mobile environment. The mobile device may write data to the second data storage zone only when the mobile device is in a non-mobile environment and may not write data to the second data storage zone when the mobile device is in a mobile environment.

Abstract: A servo system and method position a head laterally with respect to magnetic tape longitudinal defined servo bands arranged in a longitudinally shifted pattern for identification, and separated by data tracks. A servo controller responds to a loss of lateral position, sensing an estimated longitudinal position of the magnetic tape. If the estimated longitudinal position is within a predetermined distance of an end of the tape, the servo controller operates a drive to continuously move the tape away from the sensed end. The servo controller senses a home lateral position sensor to determine whether a compound actuator is within a predetermined distance of the edge of the magnetic tape. If so, it operates the coarse actuator portion of the compound actuator to move laterally away from the edge of the magnetic tape; else, to move toward the edge.