Abstract: An optical disk apparatus of the present invention measures a surface deflection component (shape of surface deflection) from a low-pass component of a compensating filter in a surface deflection measuring part provided in a DSP. Furthermore, the optical disk apparatus calculates timing at which a positional change in a surface deflection component in time required for focus jumping is a predetermined value or less in a timing calculating part, and starts focus jumping at the timing. Because of this, stable focus jumping is made possible.

Abstract: A recording and/or reproducing apparatus for a disc-shaped recording medium includes an optical head, a disc rotationally driving unit, a transfer unit, and an eccentricity amount measuring unit. The eccentricity amount measuring unit includes a controller and an error signal generator which generates an error signal exhibiting the amount of relative displacement of a light beam irradiated from the optical head onto the disc-shaped recording medium with respect to a track on such medium. The controller detects the peak and trough values of the error signal supplied from the error signal generator and compares a difference signal exhibiting a difference between the detected peak and trough values and a reference value to calculate the amount of eccentricity of the disc-shaped recording medium based on a comparison output signal.

Abstract: A tilt detection apparatus capable of detecting the tilt of the optical disk, provided with a laser for outputting a laser beam, a diffraction grating for diffracting the laser beam from said laser to generate a 0th order diffraction beam and +-first order diffraction beams which have the phase distribution equal to the phase distribution due to the wave front aberration generated on an optical disk when the optical disk is tilted, an objective lens for collecting said diffraction beams and exposing the beams to the optical disk, a photodetector for generating signals corresponding to said +-first order diffraction beams reflected at said optical disk, a signal generation circuit for generating the push-pull signals based on the generated signals, and a tilt detection circuit for detecting the tilt of the optical disk based on the push-pull signals.

Abstract: An eccentric disk detection apparatus for an optical disk device is provided. The eccentric disk detection apparatus detects eccentricity, as well as determines whether the eccentricity is high or low, by sensing and analyzing the reverse electromotive force. Upon detection of eccentricity, the eccentric disk detection apparatus can adjust the maximum number of revolutions of the disk in accordance to the sensed reverse electromotive force, thereby compensating for the eccentricity of the disk.

Abstract: An optical recording apparatus for writing information on an optical recording medium in which a recording surface is covered with a transparent layer. The information to be written on the optical recording medium is converted into a pulse signal, and spherical aberration occurring due to an error of a thickness of the transparent layer is detected, the pulse signal being controlled in accordance with the detected spherical aberration.

Abstract: Vibrations transferred to the outside are lessened and high performance against external vibrations and impact is maintained. Further, data is recorded and reproduced satisfactorily. A CD-ROM drive device is provided which is capable of reproducing data at a standard speed, a quadruple speed and a sextuple speed. When a disk is mounted to the CD-ROM drive device, TOC information is read in a playback state at the standard speed (ST1). Next, the disk is placed in a playback state at the sextuple speed and is set to a state held at a predetermined address position (ST2). It is distinguished using a tracking error signal, a control signal for a spindle motor, etc. whether the disk is either an eccentric disk or an unbalance disk (ST3). When the disk is found not to be either the eccentric disk or the unbalance disk, a playback speed is set to the sextuple speed. On the other hand, when the disk is found to be either the eccentric disk or the unbalance disk, the playback speed is set to the quadruple speed.

Abstract: An optical disk reproducing apparatus of the present invention includes a body, a disk motor which rotates a disk in which information recording tracks are formed concentrically or spirally on an information recording surface, a base fixed onto the disk motor and elastically suspended with respect to the body, and an optical head which is suspended with an elastic member from the base and is displaceable in a radial direction of the disk.

Abstract: A method and apparatus for measuring the eccentricity of an optical disk. The method for measuring the eccentricity of an optical disk in accordance with the present invention comprises the steps of activating tracking servo while the optical disk is rotating, detecting the center value of tracking error signal and setting the center value as a reference value, and detecting the eccentricity of the optical disk by comparing the center value and the tracking error signal received right after the reference value is set. The method in accordance with the present invention precisely measures the eccentricity of an optical disk and adjusts focus and track servo gains and disk rotation speed based upon the measured disk eccentricity, which provides stable data reproduction performance.

Abstract: An apparatus or method for estimating a radial speed of a disc is suitable for an optical storage device. The apparatus is used in an optical storage device for receiving a pulse signal and an eccentricity, and generating an estimated radial speed of the disc. The apparatus comprises a frequency detector and a sinusoidal wave generator. The frequency detector is used for receiving the pulse signal and then outputs a rotation frequency. The sinusoidal wave generator is used for receiving the rotation frequency and the eccentricity, and then outputs an estimated radial speed value of the disc.

Abstract: There is provided an apparatus for compensating for an eccentricity of an optical disc, including a driver on which an optical disc is mounted for rotation, an optical head for emitting optical beams to the optical disc and receiving optical beams reflected from the optical disc, a mover to which the optical head is secured and which moves in a radius-wise direction of the optical disc, a track cross generating circuit which receives a track error signal from the optical disc and transmits a track cross pulse, and a controller which receives the track cross pulse to thereby determine an eccentricity of the optical disc in view of the optical beams reflected from the optical disc, and controls a rotational frequency of the optical disc in accordance with the thus determined eccentricity. The apparatus provides an advantage that an average transfer rate is increased for the long run.

Abstract: A recording and/or reproducing apparatus for a disc-shaped recording medium which includes an optical head, a motor driven table for rotating the disc-shaped recording medium, a slider for moving the optical head relative to the motor driven table in a radial direction of the disc-shaped recording medium, an error signal generator for generating an error signal exhibiting the amount of the relative shifting of a spot of a light beam irradiated from the optical head on the disc-shaped recording medium with respect to a track on the disc-shaped recording medium, and a controller which detects a peak value and a trough value of the error signal supplied from the error signal generator and compares the difference between the detected peak value and the detected trough value with a reference threshold value to generate a drive signal for the slider on the basis of the comparison, wherein the drive signal from the controller is supplied to the slider to shift the optical head relative to the motor driven table in t

Abstract: A disk reading apparatus for reading data recorded on a disk medium is disclosed. The disk reading apparatus comprises a motor for rotating the disk medium, a vibration sensor section for detecting vibrations generating inside the disk reading apparatus and for converting the vibrations into a signal, a binarized signal generation section for extracting only a frequency component corresponding to the rotary speed of the disk medium from the signal outputted from the vibration sensor section, and for outputting a signal in which a binaraization is performed, a vibration judgement section for measuring a period of the binarized signal outputted from the binarized signal generation section and for outputting a vibration detection signal when the period of the binarized signal corresponds to the rotary speed of the disk medium, and a rotation control section for lowering the rotary speed of the disk medium when the vibration detection signal is inputted.

Abstract: For providing a optical disk driving device that is capable of accurately performing recording and reproduction also of disks including warpage without the provision of a tilt mechanism, a clamper is comprised of a central clamper portion for pinching and holding a disk with a turntable, and an outer clamper portion for abutting against an outer periphery of the disk and pressurizing the same in case the disk includes any warpage to thereby correct the warpage, if present, through pressurizing; it is accordingly possible to restrict an angle formed between a light beam and an information surface of the disk to be within a specified value for accurately performing reproduction.

Abstract: CD-ROMS of poor quality, such as those having eccentric center holes or uneven weight distributions circumferentially, are easy to wobble or otherwise vibrate when driven at high speed, overloading tracking and focusing servos and inviting read errors and retries. Each CD-ROM on being loaded into a CD-ROM drive is therefore checked as to its quality in terms of the speed of rotation at which the disk drive motor gains a steady state on being started up at a full supply voltage. The poorer the disk quality, the lower is the steady state speed of motor rotation. A poor quality disk is read at four times the standard audio CD speed, an intermediate quality disk at eight times that speed, and a good quality disk at twelve times that speed.

Abstract: A device for measuring characteristics of an optical pickup and/or an optical disc by which characteristics of tracking signals can be measured accurately in a noise-free manner. The measurement device 1 has a sample-and-hold circuit 8 and an analog-to-digital converter 10 for directly sampling an output of an optical pickup 2 as signals A to F in order to store the resulting digital data in a second memory 11. An arithmetic-logic unit 12d measures tracking error signals based on the digital data stored in the second memory 11. The arithmetic-logic unit 12d eliminates unstable portions of the tracking signals generated responsive to rotational eccentricity of the optical disc to find data.