Abstract: An optical disc master recording device can surely control an optical spot position even if an objective lens and SIL are attached to an optical head, and includes an objective lens for gathering a recording light irradiating an optical disc master, a solid immersion lens for further converging the recording light gathered by the objective lens, first drive element driving the objective lens to the radial direction of the optical disc master, second drive element driving the solid immersion lens to the radial direction of the optical disc master, unit for determining a center position of the objective lens from a reference position in the radial direction, unit for determining a center position of the solid immersion lens from a reference position in the radial direction, circuit for calculating a spot position of the recording light on the optical disc master according to the center positions of the objective lens and the solid immersion lens, and control element for controlling the first and second drive el

Abstract: A transfer control system of an information read beam for transferring an information read beam from one recording side to another in an information reader comprising offset error signal generation means for piggybacking a predetermined offset level onto a focus error signal indicating a shift from the focus position of the information read beam to generate an offset error signal in order to shape the beam form of the information read beam for reading record information from an information recording medium having a plurality of laminated recording sides on the recording side. It comprises offset level setting means for setting the predetermined offset level in the offset error signal generation means, transfer signal generation means for generating a transfer signal for forcibly transferring the information read beam, and transfer means for transferring the information read beam from one recording side to another based on the transfer signal.

Abstract: A tracking system for optical storage media e.g. an optical disk, comprising a matrix of four sensors receiving a beam reflected by the disk; one processing channel for each sensor signal, including means for producing a binary signal from the sensor signal, and an adjustable edge delay circuit operating on the binary signal; one adder for each pair of channels corresponding to diagonal sensors of the matrix; and a phase detector comparing the outputs of the adders.

Abstract: An information recording and reproducing method having a track identification function that is suitable for performing an accurate information record and reproduction for a recording medium including user information areas having any ones of land and groove tracks arranged alternately each other and identification areas having at least one pit stream arranged intersectionally each other at each side on the basis of the center line of the tracks and arranged alternately with the user information area. In the method, a first identification information signal for a pit stream recorded on one side and a second identification information signal for a pit stream recorded on the other side, on the basis of any one center line in tracks, are detected.

Abstract: A gain controlling apparatus is provided with: an adjusting device (6, 7, 8) for adjusting a gain of a generation signal, which is generated on the basis of a light reception signal obtained by receiving a reflection light of a light beam from an information recording medium (1); and a detecting device (21, 14, 16) for detecting whether or not the generation signal is generated and outputting a detection signal when the generation signal is generated. The gain controlling apparatus is also provided with a controlling device (18) for controlling the adjusting device to increase the gain by a predetermined value set in advance when the detection signal is not outputted by the detecting device.

Abstract: A disk drive system includes a servo system for driving mechanical parts, including a read/write head, to a desired track on a disk. The mechanical parts undesirably resonate at a frequency f, where f is a function of a temperature t of those mechanical parts. The servo system includes a notch filter responsive to an indication of temperature t, to attenuate the amplitude of frequency f in a broadband control signal that is applied to move the mechanical parts.

Abstract: A focus servo control system is a system for selectively applying a light beam to a disk on which data is recorded on plurally layered recording surfaces and setting the focus position of the light beam on a selected recording surface of the two-layered recording surfaces based on a signal read from reflected light from the selected recording surface of the plurally layered recording surfaces of the disk and includes a focus error detector for detecting a positional difference between the focus position of the light beam and the selected recording surface of the plurally layered recording surfaces, a sample-hold circuit for sampling and holding an output of the focus error detector, a focus position correcting circuit for correcting the focus position of the light beam based on one of the output of the focus error detector and an output of the sample-hold circuit, a data signal level detector for detecting the signal level relating to data read out from the disk, a comparator for comparing a signal level dete