Abstract: Whether an optical disc is a first optical disc or not is determined with reference to at least one of first and second focus error signal amplitude values. Then, if a sum value of the addition of a first focus balance signal value (CD-FBAL signal value) to a second focus balance signal value (DVD-FBAL signal value) is equal to or more than a predetermined threshold value, the signal surface of the optical disc is determined to be a CD signal surface of a dual disc. On the other hand, if the sum value is smaller than the predetermined threshold value, the signal surface of the optical disc is determined to be a DVD signal surface of a DVD or a DVD signal surface of a dual disc.

Abstract: In an optical recording/reproducing apparatus of the present invention, a semiconductor laser driver supplies a selected one of a plurality of drive currents, including at least a first-level drive current and a second-level drive current, to a semiconductor laser to control the emission of a laser beam by the laser. A current driver selectively outputs one of a plurality of increment currents to the laser driver in response to control signals, the plurality of increment currents including a first increment current supplied to the laser driver during an automatic power control process and a second increment current supplied to the laser driver during a special power setting process.

Abstract: The rewritable data storage medium (1) has a rewritable recording layer (9) provided with a tracking structure (8). Said layer (9) has a data recording area (5). An erasable identification mark is present in an identification mark area (4, 4?) other than the data recording area (5). The data recording area (5) has a first tracking structure (8?), whereas the identification mark area (4, 4?) is substantially free from a tracking structure or has a second tracking structure (8?) substantially different from the first tracking structure (8?). Thus erasure of the identification mark is practically impossible, because the location of the erasing spot of a recorder cannot be controlled precisely in radial direction.

Abstract: In an optical head apparatus, reflected light from the disk is diffracted by a hologram optical element, and received by an optical detector. A focusing error signal is detected from ?1st-order diffracted light of the hologram optical element. A tracking error signal by the differential phase method, a tracking error signal by a push-pull method and the data signal recorded on the disk are detected from +1st-order diffracted light of the hologram optical element. A diffraction efficiency of the +1st-order diffracted light is higher than a diffraction efficiency of the ?1st-order diffracted light.

Abstract: The present invention provides a magnetooptic device, a magnetooptic head, and a magnetic disk drive each capable of performing optically assisted magnetic recording and each having a small size, improved recording density, and a higher transfer rate. In a magnetooptic device, a magnetic circuit including a magnetic gap and a thin film magnetic transducer having a coil portion are stacked on the surface of a semiconductor laser. By the arrangement, optically assisted magnetic recording can be performed, small size and light weight are achieved, and higher transfer rate can be implemented.

Abstract: An optical record carrier (1) is provided with tracks having a groove (4) wobbled in a transverse direction and predetermined positions (18) along the track. The wobble comprises a substantially monotonous undulation (15). Local excursions (16) of the groove superposed on the undulation at the predetermined positions represent position information, such as addresses. The spatial frequency of the undulation is lower than that of the excursions.

Abstract: In an optical recording medium having a super-resolution layer structure using near-field light, comprising a readout layer 3 for forming a light scattering region 9 in the center portion of a laser spot, and a recording layer 5 for receiving near-field light 10 generated from the light scattering region 9 of the readout layer 3, scattering bodies 61 for increasing the generated near-field light are provided while enhancing a scattering effect of the near-field light 10 applied to a mark 51 of the recording layer 5.

Abstract: A recording medium on which a plurality of programs are collected in a plurality of groups and supervised in this grouped state, wherein when an editing command such as dividing, linking, and erasing the predetermined programs or groups recorded on the recording medium is executed, management data is edited to perform the editing command. The invention provides a solution to meet this request by a recording medium, an editing method and an editing apparatus.

Abstract: An information reproducing method for reproducing information recorded on a medium by irradiating a laser beam and detecting a reflected light beam from the medium. The method includes detecting a plurality of reflected light beams in which the polarities of variations in reflected light beam intensity distributions are substantially inverted to each other, the distribution variation being produced when a light spot of the laser beam crosses a track on the medium, generating components of a focus error signal and components of a tracking error signal, adding the components of the focus error signal of the plurality of reflected light beams to generate a focus error signal, and taking a difference between the components of the tracking error signal of the plurality of reflected light beams to generate a tracking error signal.

Abstract: When a medium is stored or removed manually, all slots must be checked to find any change in medium information, and as a result, updating medium storage information takes a long time. A medium controller, having a plurality of media and a medium transfer unit to take a medium in and out of storage and move the medium for reading or writing information, comprises slots in which media are store, sensors each mounted in a slot for detecting whether there is a medium in the slot; a sensor manager for holding a log of the status transitions of the sensors in a period when media are likely to be stored or removed manually and deciding the status transitions; and means for reading medium information. Only when it is decided from a decision result of the sensor manager that the medium has been replaced, the media controller causes the means for reading medium information to read medium information in order to update the medium storage information.

Abstract: Multibeam optical disk record and reproduction apparatus and method, in which at least two light beams generated are concentrated in different positions of on recording tracks of a recording medium to record or reproduce data to or from the recording medium on the different positions at the same time. The light beams are moved independently of each other across the recording tracks so that any one light beam is movable during the recording or reproducing of data by another light beam. This allows parallel recording/reproducing with a plurality of light beams without producing areas unaccessed due to the jumps of the light beams.

Abstract: A disk recording medium has reliability of address reading which is maintained equivalently to the conventional disk recording medium by recording a first address and a second address that are identical in a header area. By arranging the first and second addresses to be reversely displaced from the center line of a groove track or a land track to the radial direction of the medium, the distance between the first and second addresses when they are adjacent is increased, which eliminates the influence of crosstalk. This avoids redundancy of the header area and enables high-density recording to the disk recording medium.

Abstract: Methods and apparatus are provided for detecting and correcting magnification errors while simultaneously reading or writing multiple data tracks with a multi-beam optical disk drive. An optical head for the optical disk drive includes a plurality of laser diodes that generate multiple light beams for reading from or writing to the optical disk, means for detecting a magnification error, and means for compensating for the magnification error to align the multiple light beams with multiple data tracks. A number of opto-mechanical systems are provided for correcting the magnification errors in the beams.

Abstract: An optical record carrier comprises substantially parallel tracks being divided into recording units having an address area (23,24), adjacent address areas of adjacent tracks (43,44) comprising shared address marks (48). Shared address marks (47,48) are positioned in between adjacent tracks and arranged in sharing portions (40,41) of the address area, each sharing portion sharing address marks only to one side. The address area also comprises a free portion (39) which is free from shared address marks, which free portion is aligned with a sharing portion (42) of an adjacent address area. This is advantageous for reducing crosstalk in the address read signal. The sequence of the free and sharing portions within an address area differs so as to be matching in adjacent address areas.

Abstract: A magnetic recording or reproducing apparatus having a rotary drum includes a sensor for detecting dew condensation on the rotary drum, a take-up reel for taking up a recording medium, and a controller for controlling the rotary drum and the take-up reel in accordance with a result of detection provided by the sensor. When dew condensation has been detected by the sensor, the controller causes the rotary drum to rotate in such a way as to release the recording medium from a state of sticking to the rotary drum and, after that, causes the recording medium to be taken up by the take-up reel.

Abstract: A copy command corresponding to a SCSI protocol is issued from a host computer 101 to a destination data recorder 102r through a SCSI bus 76. The recorder 102r that has received the copy command from the host 101 sends a one-byte read command corresponding to the SCSI protocol to a source data recorder 102t. If the size of a block to be sent is not one byte, the difference is sent as an error byte to the source recorder 102t.

Abstract: The orientation of a tape cassette is automatically determined as it is being loaded into the tape drive by the transport mechanism. A reference edge of the cassette (for example, a predetermined lower edge of a DAT tape cassette) is characterized by a distinctive non-symmetrical profile of transparent and opaque edge portions, and a radiation source and sensor are positioned within the transport mechanism along a radiation axis that intersects an adjacent edge of the cassette as it is being loaded into the tape drive. The sensor output thereby produces a signal from which it can be determined whether the cassette is oriented with its reference edge intersecting the radiation axis. In a preferred embodiment, the output of the sensor is converted into a digital signature which is compared with a stored signature corresponding to the distinctive profile associated with the reference edge.

Abstract: Apparatus for detecting data track misregistration is described. The present invention involves the interaction of a microprocessor with a demodulator. Microcode within the microprocessor initiates a misregistration scan of all data tracks at specific intervals to generate a calibration offset table that is used to direct the heads during the subsequent interval. A demodulator obtains the peak values of calibration servo bursts, displaced one-half of the track width to either side of a track, and outputs a timing pulse proportional to their respective peak voltage values. A timer within the microprocessor extracts the time values, and the misregistration displacement is calculated by the comparison of the inner burst and outer burst time values. The calculated displacement is used in the offset table for subsequent disk references.

Abstract: A digital servo control system for a disk drive provides asynchronous servo information signal demodulation. The system includes a digital demodulator having a digital squarer that removes any phase component of the digitized servo information signal and includes a burst signal accumulator that accumulates the squared terms according to respective burst timing intervals to produce a digital, quadrature position error signal (PES). The demodulator also can include a filter comprising a harmonic notch filter preferably implemented as a Hilbert Transform filter. Alternatively, the demodulator does not include a filter and squarer and, instead, the squarer comprises a sum-and-squarer that sums the squares of odd and even digitized samples. A split burst servo pattern for the servo control system is comprised of half-width transitions that can be written in a single pass of a recording head and therefore has no phase misalignment between adjacent flux patterns.

Abstract: A system for calibrating a magnetic tape drive for accurate movement of a tape head or drive motor accommodates mechanical and manufacturing inaccuracies. Motion is corrected through sensing variations from desired position or speed through operation of the drive in one continuous motion. These values may then be processed or filtered to remove non-repeatable effects and thus achieve appropriate correction in operation. The values may be written to a ROM in tabular format correlating position correction values with track number or adjusting speed coefficients for use during operation. For the tape head, actual position values are sensed in one substantially continuous motion of the tape head through a move command for faster calibration.