Abstract: A type of disc is judged at high reliability irrespective of a presence of information record or magnitude of disc eccentricity. A reproduction apparatus judges the type of an optical disc to reproduce information recorded on tracks of the optical disc. The disc is classified as a type of read-only optical discs whose tracks are formed with pits and as a type of recordable optical discs whose tracks are formed with wobbling grooves. The apparatus includes a motor which rotates the optical disc, a head which irradiates the tracks of the optical disc rotated by the motor with an optical beam and outputs two detection signals corresponding to reflected light from the optical disc, and a controller which judges the type of the optical disc according to changes of a period of a specific signal contained in a push-pull signal generated from the two detection signals by varying a rotating speed of the motor.

Abstract: A seat slide for a vehicle, including a lower rail fixed to a floor of the vehicle, an upper rail fixed to a seat of the vehicle, a lock plate disposed within an inner space between the lower and upper rails and secured to the lower rail, a latch lever with a pawl which is disposed within the inner space and pivotally supported by the upper rail, and a position sensor for detecting a position of the upper rail relative to the lower rail, the position sensor being mounted to the upper rail such that a sensing portion thereof is disposed within the inner space and opposed to the lock plate.

Abstract: An optical disc device according to the present invention is provided with, as shown in FIGS. 1 and 2, a high frequency band processing circuit for removing low frequency components of signals outputted from plural photodetectors of a pickup, and generating various kinds of signals required for recording/playback of an optical disc by digital processing after performing AD conversion by a high-speed low-bit AD converter; and a low frequency band processing circuit for removing high frequency components of the signals outputted from the respective photodetectors of the pickup, and generating various kinds of signals required for recording/playback of an optical disc by digital processing after performing AD conversion by a low-speed high-bit time-division AD converter. Thereby, various kinds of signals required for recording/playback of an optical disc can be generated using a single circuit, whereby the product cost, power consumption, and circuit scale can be reduced.

Abstract: According to the present invention, a moving element Ai such as an electrostatically driven actuator is displaced by supplying a drive signal thereto. Meanwhile, a displacement sensing section 6 senses its displacement and a calibrating section 15 automatically calibrates the correlation between the drive signal and the displacement, thereby compensating for a variation in the characteristic of the actuator with time and according to the environment. A switching section 7 selectively connects the single displacement sensing section to a plurality of moving elements Ai one after another, thereby cutting down the circuit for displacement sensing.

Abstract: An optical disc drive according to the present invention may be loaded with an arbitrarily selected one of optical discs of multiple types including a first optical disc with grooves and a second optical disc with no grooves.

Abstract: To greatly increase the storage density of a storage apparatus, an electron beam E emitted from a cold cathode 101 is accelerated by an accelerating electrode 102, caused to converge by a convergence electrode 103, deflected by a deflection electrode 104 and applied to a minute region of a storage film 105. The storage film 105 includes, for example, a phase change film 105a. The film is rapidly heated and cooled to change into an amorphous state upon irradiation with an electron beam E with high energy, while being gradually cooled to change into a crystallized state upon irradiation with an electron beam E with approximately intermediate energy, thereby storing data. Upon irradiation with an electron beam E with low energy, the potential difference between a detection electrode 105b and an anode 105c is detected depending on the state, i.e., the amorphous or crystallized state, thereby reading stored data.

Abstract: An optical disc that has a recognition mark area behind a recorded area and in which the last data in the recorded area is stably accessed, the recognition mark area can be accessed without bringing about an abnormal state, and the first data in a succeeding recorded area, if it exists, is stably accessed. An unrecorded area (5) is provided outside the recorded area (4) of the optical disc (1). A mark area (6) is provided between the recorded area (4) and unrecorded area (5). A recognition mark area (6d) is provided in the mark area (6) in order to recognize the boundary between the recorded area (4) and the unrecorded area (5). In the mark area (6), first and second buffer areas (6b and 6c) are provided respectively in front of and behind the recognition mark area (6d).

Abstract: A servo error signal generation circuit comprises a first sampling unit for sampling first detection signals at first sampling timings, a second sampling unit for sampling second detection signals at second sampling timings which are obtained by periodically thinning out the first sampling timings, an AD converter for analog-to-digital converting the data sampled by the first and second sampling units, and a completion unit for completing the sampling date of the timings which have been thinned out by the sub sampling timing generator, for the data which have been sampled by the second sampling unit and outputted from the AD converter.

Abstract: An optical disk of the present invention includes a pre-recorded region in which pre-recorded data is recorded; a recordable region in which a first clock synchronization mark and first address information are recorded; and a synchronization region having a prescribed length which is positioned between the pre-recorded region and the recordable region.

Abstract: An optical disc drive includes: an optical head with an actuator and a photodetector; a tracking driver outputting a drive signal to the actuator; a first tracking error signal generator for generating a first tracking error signal based on an output signal of the photodetector; first and second lens position control sections for respectively outputting first and second lens position control signals to the tracking driver; and a selector for selectively supplying the first tracking error signal to the first or second lens position control section according to a moving velocity of the optical head during a seek operation. The first lens position control signal is obtained by extracting signal components, of which the frequencies are equal to or lower than a predetermined frequency, from the first tracking error signal. The second lens position control signal is obtained by extracting DC components of the first tracking error signal at on-track points thereof.

Abstract: An information playback apparatus comprises an input amplifier to which an RF signal reproduced from an optical disc is input; a high-pass filter to which the output of the input amplifier is input; an AD converter to which the output of the high-pass filter is input; a lag lead filter to which the output of the AD converter is input; and a demodulator for digitally processing the output of the lag lead filter to demodulate it as a binary signal. Thereby, an optical disc playback apparatus that realizes a DVD-RAM playback function at low cost can be realized.

Abstract: An optical disc reproduction apparatus includes a sector detection section for detecting a sector; a sector reproduction time measuring section for measuring a reproduction time of the sector, and outputting sector reproduction time data which represents the measured reproduction time of the sector; an unrecorded portion detection section for detecting an unrecorded portion which is a portion of the sector in which no data is recorded; an unrecorded portion time measuring section for measuring a reproduction time of the unrecorded portion, and outputting unrecorded portion time data which represents the measured reproduction time of the unrecorded portion; and a sector determination section for determining whether the sector is an unrecorded sector or not, based on a relationship between the sector reproduction time data and the unrecorded portion time data, the unrecorded sector being a sector which is in an unrecorded state.

Abstract: An optical disc drive reads and/or writes data from/on an optical disc with sectors, each including a header area, having two or more identical marks or pits with a predetermined length, and a user data area.

Abstract: A laser power control circuit that is constituted by CMOS transistors reduces variations in a laser power that is emitted from a semiconductor laser, which are caused by a mismatch of the transistors. An offset amount of a differential amplifier is digitally calculated using an A/D converter that is located on the same chip, and a voltage value of a variable voltage source is controlled for applying a voltage in a direction opposite to the offset voltage of the differential amplifier to correct the offset voltage of the laser power control circuit, thereby reducing the variations in the laser power emitted from the semiconductor laser.

Abstract: An optical disc drive according to the present invention may be loaded with an arbitrarily selected one of optical discs of multiple types including a first optical disc with grooves and a second optical disc with no grooves.

Abstract: A tracking error detection apparatus comprises a phase difference detection circuit for receiving two sequences of digital signals, and performing phase comparison using a distance between zerocross points of the two sequences of digital signals to output a result of phase comparison, and an LPF for generating a tracking error signal from the result of phase comparison. The phase difference detection circuit does not carry out phase composition in a position that is not appropriate as a target position to perform phase comparison, and outputs the result of phase comparison as a pulse signal corresponding to one sampling clock. Therefore, even when a disc is played at CAV or a flaw or the like exists on the disc, an accurate tracking error signal can be detected.

Abstract: An optical disc that has a recognition mark area behind a recorded area and in which the last data in the recorded area is stably accessed, the recognition mark area can be accessed without bringing about an abnormal state, and the first data in a succeeding recorded area, if it exists, is stably accessed. An unrecorded area (5) is provided outside the recorded area (4) of the optical disc (1). A mark area (6) is provided between the recorded area (4) and unrecorded area (5). A recognition mark area (6d) is provided in the mark area (6) in order to recognize the boundary between the recorded area (4) and the unrecorded area (5). In the mark area (6), first and second buffer areas (6b and 6c) are provided respectively in front of and behind the recognition mark area (6d).

Abstract: An optical disc that has a recognition mark area behind a recorded area and in which the last data in the recorded area is stably accessed, the recognition mark area can be accessed without bringing about an abnormal state, and the first data in a succeeding recorded area, if it exists, is stably accessed. An unrecorded area (5) is provided outside the recorded area (4) of the optical disc (1). A mark area (6) is provided between the recorded area (4) and unrecorded area (5). A recognition mark area (6d) is provided in the mark area (6) in order to recognize the boundary between the recorded area (4) and the unrecorded area (5). In the mark area (6), first and second buffer areas (6b and 6c) are provided respectively in front of and behind the recognition mark area (6d).

Abstract: In a recordable data storage medium on which property data was recorded after having been modulated and on which data that is decodable by a cryptographic key to be generated from the property data was recorded, the property data was preferably modulated by a different method from that applied to a read-only data storage medium. Then, an optical disc drive, having no ability to distinguish the recordable data storage medium from the read-only data storage medium, cannot read the recordable data storage medium. Consequently, a greater number of drives should be equipped with the function of recognizing the type of a given data storage medium and the copyright protection function should be consolidated.

Abstract: Tilt which is inclination of a normal of optical disk relative to optical axis of optical head is corrected with a liquid crystal element. In a driver for the liquid crystal element, a periodic waveform generator generates periodic waveform and an inverting element inverts the periodic waveform. The periodic waveform and the inverted waveform are connected to two ends of a potential divider which provides partial voltages. The periodic waveform is connected to a common electrode of the liquid crystal element, and the partial voltages of the potential divider are connected to electrodes opposing the common electrode. A structure of a driver circuit for each direction is simple. Tilt in a plurality of directions can be performed independently of each other. Spherical aberration is also corrected. When the liquid crystal element is mounted to a fixed component, deterioration due to jitters is reduced.