Abstract: According to one embodiment, there is to provide a disk drive which calculates an error in the position of a head on the basis of concentric servo patterns. The disk drive has a disk medium on which spiral servo patterns are recorded and a read head which reads the spiral servo patterns from the disk medium. A servo controller reproduces a hexagonal burst signal from the spiral servo patterns read by the read head to generate position data associated with servo burst signals. The CPU uses the position data to perform a position error calculation.

Abstract: Embodiments of the present invention help to prevent destabilization in voice coil motor (VCM) velocity control. According to one embodiment, a hard disk controller/multiprocessing unit (HDC/MPU) calibrates a correction operational coefficient of a detected back electromotive force (EMF) voltage before unloading. The calibration is carried out in a state that an actuator is pivoting. The HDC/MPU calibrates the correction coefficient according to a motion equation of the actuator using VCM current applied to a VCM and a detected value of a back EMF voltage detection circuit.

Abstract: An optical pick-up device in which two object lenses correct comatic aberration with respect to object lenses. First and second optical systems converge either one of light beams having first, second and third wavelengths onto an optical disc. Object lenses are displaced in three axial focusing directions including a direction perpendicular to the recording surface of the optical disc, a tracking direction radial to the optical disc, and either one of a radial tilt direction in a circular arc form on the axis of the radial direction and a tangential tilt direction in a circular arc form on the axis in a tangential direction perpendicular to the radial direction. Comatic aberration of the second optical system is corrected relative to the first optical system in the other direction of the radial tilt direction and the tangential tilt direction, which is not controlled by the object lens drive unit, is corrected.

Abstract: A data buffering method used when performing a read operation on an optical storage medium is disclosed. After a first data unit having an unidentifiable and temporarily undeducible ID address is reproduced through the read operation, the method starts storing the first data unit and subsequently reproduced data units into a buffer memory in turn. After a second ID address of a second data unit of the subsequently reproduced data units is identified, the method deduces a target memory address of the buffer memory according to the second ID address and a target ID address. A buffer start pointer is then set according to the deduced target memory address.

Abstract: The invention provides for modifications to conventional optical data storage media to reduce the amount of raw material necessary in the media construction. More particularly, a portion of a thermoplastic substrate is modified to create one or more substantial void areas compared to a conventional substrate that defines flat parallel surfaces without void areas. The configuration, number, and size of the voids may be modified in order to substantially reduce inherent raw material cost while maintaining the specified physical thickness, clamping area, and mechanical stability of the medium.

Abstract: It is related to a head control method. The head control method controls a protruding flying height of a head in which an energization amount applied to a heater element in the head to thermally expands the head. The head control method includes a resistance-value measuring step of measuring a resistance value of the storage element, an energization-amount calculating step of calculating an energization amount applied to the heater element such that the resistance value measured in the resistance-value measuring step reaches a reference resistance value, and a heater control step of performing control to apply the energization amount calculated in the energization-amount calculating step to the heater element.

Abstract: In a recordable optical disc apparatus, the efficiency of the work necessary for optimizing the write pulse condition (write strategy) is improved and the read compatibility among drive units is ensured by a minimum addition of circuitry. An edge shift amount or a read signal and a binarized result are stored in an external memory as digital data and are later processed by analysis software in a host PC. The write pulse shape and power conditions can be optimized to individual optical disc media in a short time by means of a simple circuit. Further, by optimizing the write pulse shape and power condition in view of the PRML class or the difference in NA of the head, any deterioration of read compatibility can be avoided.

Abstract: A reproducing apparatus includes a head unit operable to direct a laser light beam onto a recording medium, the head unit having a focus servo mechanism and a spherical aberration correction mechanism for laser light; an evaluation signal generating unit operable to generate an evaluation signal serving as an index of quality of a reproduced signal; a focus servo unit operable to perform a focus servo operation by driving the focus servo mechanism in response to a focus error signal; a spherical aberration correction unit operable to perform spherical aberration correction by driving the spherical aberration correction mechanism in response to a spherical aberration correction value; a focus bias unit operable to add a focus bias to a focus loop containing the focus servo unit; and a control unit operable to control adjustment of a spherical aberration correction value and a focus bias value to be set in the spherical aberration correction unit and the focus bias unit, respectively.

Abstract: Embodiments of mitigating the effects of disturbances of a disk drive are disclosed. One method includes sensing a position error signal of a transducer coupled to a surface of the disk drive, wherein the position error signal aids in control of an actuator of the disk drive. A first disturbance signal is generated by sensing a disturbance of a first sensor attached to the disk drive, wherein the first disturbance signal aids in control of the actuator. A second disturbance signal is generated by sensing a disturbance of a second sensor attached to the disk drive, wherein the second disturbance signal aids in control of the actuator. Effects of the disturbances on the position error signal are reduced by adaptively adjusting a gain of the first disturbance signal and a gain of the second disturbance signal.

Abstract: A kind of an optical disc is discriminated by a disc discriminating section, an order of aberrations to be corrected is set by an order setting section by the kind of the optical disc, drive of a liquid crystal optical element is controlled by a drive control section through a liquid crystal driver, and an aberration of an optical beam is corrected based on the order of the aberration. The level of importance of the aberration correction differs by the kind of the optical disc, and the order of the aberration is set by the level of importance of the aberration correction.

Abstract: Disclosed is a method for reducing occurrences of tape stick conditions in magnetic tape, the method including stopping functional rotation of each of two bi-directionally rotatable reels of a reel-to-reel tape drive that includes a length of magnetic tape at least partially wound around each reel, a portion of the length of tape extending between the two moveable reels and contacting a head positioned between the two reels; wherein the stopping creates a stop condition in the tape drive, actuating a fractional rotation at least one of the two bi-directionally movable reels a fraction of a reel turn in a first direction during the stop condition, causing the portion of the length of tape to at least temporarily break contact with the head via the fractional rotation, and re-starting functional rotation of each of the reels, ending the stop condition via the re-starting.

Abstract: A head integrated circuit for driving a head. The head includes at least a head unit and a heating element for adjusting the spacing between the head and a storage medium. The head integrated circuit includes at least a read amplifier for amplifying the read signal from the head unit and a heater drive circuit for driving the heating element. The heater drive circuit includes a measuring circuit configured to measure the level of power supplied to the heating element, an error calculating circuit configured to calculate an error between a predetermined power level and the measured power level, a pulse width modulation circuit configured to modulate the error into a pulse width, and a switch configured to operate in response to a pulse from the pulse width modulation circuit and supply power to the heating element.

Abstract: A disk drive having a single drive motor and multiple platters that incorporates two discrete data paths, actuators and heads to the disk platters. Utilizing the economy of very large capacity disk platters, two or more disk drives can be created within a single physical enclosure. These two disks will be share many common parts such as the drive enclosure and spindle motor, but will have the performance and appearance to the system as two or more independent disks. Instead of having one actuator arm, the virtual disks will have two or more actuator arms and two or more sets of digital electronics. The storage on all the platters is divided up among the actuators so that no storage location is shared, but all the actuators will operate concurrently. Each actuator will have exclusive use of a subset of the data storage. Disks normally only have one actuator connected to multiple heads, at least one per surface, which only allow a single data seek and data transfer at a time.

Abstract: In a method for adjusting a write strategy, data is written into the optical disc according to a first write strategy in forms of a first type of data storage structures with variable lengths and a second type of data storage structures with variable lengths. A plurality of the first type of data storage structures corresponding to a specified reference length are located, and the recording lengths thereof are operated with the specified reference length to obtain a first averaged deviation. A plurality of the second type of data storage structures formed next to the first type of data storage structures are located, and the recording lengths thereof are operated with respective reference lengths to obtain a second averaged deviation. A parameter of the first write strategy is adjusted so as to generate a second write strategy for subsequently writing data into the optical disc.

Abstract: Plural grooves or lands formed in an information recording carrier include at least a wobbling region and data is recorded wobblingly in this wobbling region by phase shift modulation while recorded digitally with a single or multiple waves as a channel bit.

Abstract: A method of recording and/or reproducing data on and/or from an information recording medium including a compatibility information area in which compatibility information, which specifies whether each area on the information recording medium is recordable and/or reproducible, is recorded, the method includes reading the compatibility information, which specifies whether each area on the information recording medium is recordable and/or reproducible; and recording and/or reproducing the data on and/or from the information recording medium with reference to the compatibility information, wherein if other write protection forms of the information recording medium exist, write protection of the information recording medium is determined, based on a result of performing an OR function on the compatibility information and the other write protection forms.

Abstract: A liquid crystal lens element is provided, which does not produce change of transmission wavefront regardless of polarization state of incident light when it is off-state at a time of no voltage application, and which exhibits concave lens function for extraordinarily polarized incident light when it is on-state at a time of voltage application.

Abstract: A method for recording information on an optical recording medium in which a laser beam modulated into one or a plurality of write pulses with one or a plurality of write powers in accordance with target data to be written is projected onto a recording layer of the optical recording medium to form a record mark. During recording the information on the optical recording medium, a data level and a weight index are assigned to each channel bit in reference data trains before and after the target data. Recording compensation of the target data is carried out in accordance with the sum totals of the products of the data level and the weight index in the reference data trains, so that it is possible to easily carry out high a real recording by writing fine mark/space trains.

Abstract: The objective optical system of the present invention includes a first diffraction structure that applies diffraction to the light fluxes of wavelength ?1, wavelength ?2 and wavelength ?3 so that the diffracted lights of the L-th order (L: odd number), M-th order (M: integer) and N-th order (N: integer) each will have the maximum diffraction efficiency, and a first optical path difference-generating structure that substantially provides a phase difference to or two of the light fluxes of wavelength ?1, wavelength ?2 and wavelength ?3.

Abstract: An apparatus for and a method of detecting a wobble signal in accordance with a time shift includes comparing a basic wobble signal with reference levels to detect pulses representing the time shift in an analog fashion, and digitally determining a code value for the basic wobble signal on the basis of the widths of the pulses using a channel clock signal and a wobble clock signal. The determined code value is accumulated and serves as a basis on which final wobble data is produced.