Abstract: A lensless optical servo system has an unfocused light source and patterned photodetectors. The unfocused light is reflected by markings on a rotating disk and the reflected light carriers the pattern of the markings to the photodetectors. The convolution of this light pattern and a mating geometric pattern on the photodetectors causes the photodetectors to generate signals representing the position of the track on the disk. In one embodiment, a laser diode and three detectors are formed on the same silicon substrate. Sinusoidal metalization is applied to the detectors in the radial direction. The period of the sinusoidal metalization is two times the tracking pitch of the disk. The metalization on the first detector is approximately ninety degrees behind the metalization on the second detector and the metalization on the third detector is approximately ninety degrees ahead of the metalization on the second detector.

Abstract: A recording medium stores information that is reproducible utilizing near-field light. A phase shift arrangement layer is formed with alternately arranged phase shifter regions for shifting incident light by 180 degrees and transmission regions that are transparent to the incident light. A row of data marks is arranged above the phase shifter regions and transmission regions. As a result, the spread of near-field light due to incident light transmitted through the phase shifter regions and transmission regions is canceled, to provide a sharp distribution of near-field light over the data marks. light.

Abstract: This invention provides method and apparatus for controlling reproduction speed of an optical disk, which detects the magnitude of a disk vibration after initial operation of an optical disk and adjusts the disk rotation speed based upon the vibration magnitude. The method according to this invention comprises the steps of rotating an installed optical disk; detecting the quantity of signal derived from tracking error signals which are combined from signals reproduced from the optical disk when the rotation speed reaches to a predetermined speed; and deciding whether to increase the rotation speed above the predetermined speed based upon the detected quantity of the signal. This invention is able to reproduce an optical disk at the possible maximum speed within allowable speed limit through detecting accurate disk vibration magnitude at the initial operation stage and adjusting the reproduction speed to higher speed.

Abstract: An optical disc discrimination apparatus and method which discriminate a type of a disc loaded on a DVD-RAM drive accurately and simply. The optical disc discrimination apparatus includes an RF envelope generator which detects an envelope signal from an RF signal read from a disc loaded in an optical disc recording and/or reproducing apparatus at an off-track state, when only a focusing is accomplished prior to performing a tracking control, an envelope amplitude detector which detects the amplitude of the detected envelope signal, and a disc discriminator which compares the amplitude of the detected envelope signal with predetermined reference level and discriminating whether the disc is a CD, a DVD-ROM, or a DVD-RAM, based on the comparison result. Thus, a type of the disc can be discriminated simply and accurately with a change in the amplitude of the RF signal.

Abstract: In a signal detection circuit for an optical disk, a comparator converts an analog HF signal into a digital HF signal by using a slice level. A dropout detection circuit detects a dropout of the digital HF signal. A charge-pump circuit feeds back a slice-level control voltage to the comparator based on a result of the detection by the dropout detection circuit. A voltage follower holds and outputs a voltage stored in the capacitor. A switch is turned OFF when a dropout signal has been detected, and outputs to the voltage follower the voltage that has been stored in the capacitor during an ON state of the switch. A second switch is turned ON when a dropout signal has been detected, and applies an output of the voltage follower to the comparator.

Abstract: A record carrier (1) is described comprising a servo track (4) indicating an information track (9) intended for recording information blocks represented by marks having lengths expressed in channel bits, which servo track (4) has a periodic variation of a physical parameter. The periodic variation is modulated for encoding record carrier information, such as addresses. The modulation is a bi-phase modulation in which a data bit of the record carrier information is encoded by a first predetermined number of variations of a first phase followed by the same number of variations of a second phase inverse to the first phase. A recording and/or playback device has a demodulator for retrieving data bits of the record carrier information from a first predetermined number of variations of a first phase followed by the same number of variations of a second phase inverse to the first phase.

Abstract: A data storage disk includes a writeable area that allows a user to write data, wherein the data files are written from the outside diameter towards the inside diameter of the writeable area, while file system information is written from the inside diameter towards the outside diameter of the writeable area. This optimizes the use of the writeable area, whether a large number of small data files or a small number of large data files are being stored. To further optimize the use of the writeable area, information may be stored in two or more different error correction code (ECC) block sizes. Thus, information, such as the file system attributes and linking sectors, which contains few bytes may be stored in the smaller ECC block size, while the data may be stored in the larger ECC block size. The data storage disk, may also include a mastered content area.

Abstract: The beam reflected by the mobile carrier is picked up by an optical pickup having several photodetectors. The elementary signals respectively delivered by the photodetectors are used to formulate two secondary signals, sampled and filtered by a low-pass filter having a cutoff frequency at most equal to a quarter of the sampling frequency. The mutual phase shift of the two secondary signals is representative of the positioning error TE of the beam with respect to the track. The determination of a value of the mutual phase shift comprises the selecting, for each secondary signal, of at least one pair of samples situated outside a predetermined amplitude range around a predetermined threshold. This makes it possible to tag, respectively for the two secondary signals, two transitions of these secondary signals with respect to the threshold and corresponding to one and the same direction of crossing of the threshold.

Abstract: An optical disc recording and reproducing apparatus realizes stable tracking control for correcting the displacement of an objective lens caused by gravity depending on the positional attitude of the apparatus.

Abstract: In an information recording method and apparatus, a sequence of sync frames indicative of data is recorded onto tracks of an optical recording medium. In the recording medium, prepits are formed on lands between the tracks at given intervals, and sync patterns, providing synchronization on a sync-frame basis, are inserted in the sync frames such that each sync pattern has a length in a track direction larger than a length of one of the prepits and a position of each sync pattern matches with a position of at least one of the prepits. Codes that represent sync patterns for the sync frames are selected such that each sync pattern is formed as a space on the recording medium. Modulation codes are generated based on the sync frames in which the selected codes are inserted, by modulating the sync frames containing the selected codes in accordance with a predetermined modulation scheme. A sequence of recording pulses is generated by converting the modulation codes through a predetermined conversion scheme.

Abstract: An optical disc has spatial features (notches, bumps, etc.) that intentionally distort the analog Read Data signal. For a mark or space that is centered on a spatial feature, the distortion does not affect the resulting binary Read Data signal. If an edge of a mark or space is near the spatial feature, the resulting binary Read Data signal is altered. For calibration, marks or spaces are written adjacent to spatial features, with a range of times for initiating the writes. The result is a range of write times that do not alter the binary Read Data signal. From these known times and spatial locations, it is known when a mark or space must be written to ensure accurate spatial placement.

Abstract: A disk device has an optical pickup feed mechanism for reciprocating an optical pickup between the inner peripheral side and the outer peripheral side of a disc in the radial direction thereof. The optical pickup feed mechanism includes a threaded shaft threaded with a thread portion formed on an optical pickup main body for reciprocating the optical pickup main body in the radial direction of the disc while supporting it, a rotating drive source for reciprocating the optical pickup main body, and a rotation transmission gear fixed to an end of the threaded shaft for transmitting the rotation of the rotating drive source to the threaded shaft.

Abstract: An information recording and reproducing apparatus in accordance with the present invention has a radiation light source, a collimator turning a light beam emitted from the radiation light source into substantially parallel light, a light beam convergence member focusing the light beam on an information carrier, a light beam polarization-branching member branching the light beam by polarization, a variable wave plate located between the collimator and the light beam convergence member, photo detectors receiving the light beam branched by the light beam polarization-branching member and outputting a current according to an incident light quantity, and an output level judging member judging whether an output of the photo detectors is larger or smaller than a predetermined value.

Abstract: A tilt control apparatus includes an orthogonal shift detector (9) which detects an orthogonal shift by comparing a pair of a plurality of tap coefficients (C1, . . . , C7) of a FIR filter and generates an orthogonal shift signal, and an actuator varies the inclination of the optical axis of the light beam to correct the orthogonal shift, and a tilt controller (10) controls the drive of the actuator in accordance with the orhogonal shift signal to minimize the orthogonal shift. In the information recording operation, the orthogonal shift obtained based on a recording track is previously stored in a temporary storage portion and the stored orthogonal shift is used to conduct the tilt control.

Abstract: A wobble-signal detecting device detects a wobble signal based on a signal which is the difference between outputs of two divisions of a light receiving device. These two divisions are located on both sides of a line parallel to a target portion of an information recording track. This light receiving device receives light reflected by a recording medium as a result of an optical beam being incident on the recording medium. This recording medium contains the information recording track, which wobbles at a predetermined frequency, and has pre-pits formed at predetermined intervals in areas between the information recording tracks.

Abstract: An optical pickup compatible between a digital video disc read only memory (DVD-ROM) and a compact disc rewritable (CD-RW), which is a member of the CD family media. The compatible optical pickup includes: a first light source for emitting a first light having a predetermined wavelength; a second light source for emitting a second light having a long wavelength relative to the first light; an optical path changing unit for changing the traveling path of an incident light; an objective lens for condensing the first and second lights onto optical discs having different thicknesses, respectively; and a main photodetector for detecting an information signal and error signals from the first and second lights which have been reflected by the optical discs and passed through the optical path changing unit.

Abstract: A record carrier is described comprising a servo track indicating an information track intended for recording information blocks represented by marks having lengths expressed in channel bits, which servo track has a periodic variation of a physical parameter. The periodic variation is modulated for encoding record carrier information, such as addresses. The modulation is a bi-phase modulation in which a data bit of the record carrier information is encoded by a first predetermined number of variations of a first phase followed by the same number of variations of a second phase inverse to the first phase. A recording and/or playback device has a demodulator for retrieving data bits of the record carrier information from a first predetermined number of variations of a first phase followed by the same number of variations of a second phase inverse to the first phase.

Abstract: An optical disc has spatial features (notches, bumps, etc.) that intentionally cause read errors if arbitrary data is recorded on the disc in an area where the special features are located. The spatial features are located such that they occur in the center of longer marks or spaces of pre-determined data patterns. This allows pre-determined data patterns to be written and read without a significant number of errors, while arbitrary data patterns will be subject to a significant number of errors, rendering the arbitrary data unreadable. Control Data ECC blocks are partially pre-determined at least in the areas containing decryption keys, while still permitting some arbitrary data to be written in other areas of the Control Data ECC blocks. Therefore, compatibility with existing drives is preserved, without representing a threat of unauthorized copying of stamped discs.