Teac Corporation

Mitsubishi Denki Kabushiki Kaisha

Mitsumasa Kubo

Akira Mashimo

Masashi Tanaka

Yuichi Sakamoto

Tohru Miura

Tetsuro Araki

Yoshiyuki Otsuka

Kiyoshi Fukuchi

Yukihiko Okada

Hiroshi Tsuyuguchi

Teruo Furukawa

Naoto Takeda

Masayoshi Shimamoto

Yutaka Kobayashi

Akira Shinohara

Tadao Yamanouchi

Fumio Hishiyama

Yoshiyuki Ootsuka

Tsuyoshi Oyamatasu

An optical disk inspecting apparatusplays an optical disk at a high speed and determines, based on error information provided during the high-speed reproduction, whether or not errors of a number exceeding a first threshold value have occurred. Then, when it is determined that errors of a number exceeding a first threshold value have occurred, the optical disk inspecting apparatusperforms high-speed principal determination of executing high-speed reproduction in this segment and determining presence or absence of errors of a number exceeding a second threshold value and also performs low-speed principal determination of executing low-speed reproduction in this segment and determining presence or absence of errors of a number exceeding the second threshold value. When errors of a number exceeding the second threshold value are detected, it is determined that there is a defect, and NG is outputted.

Optical disk inspecting apparatus and method

A data recording apparatus and a data reproducing apparatus which ensure security of a portable recording medium, such as an optical disk. The apparatus has a security mode and a normal mode as operation modes. In the security mode, a system controller of the apparatus records a security identification signal in an area other than a user data area of the optical disk. At the time of copying of the optical disk, the security identification signal disappears, and a limitation is imposed on reproduction, thereby preventing copying operation. In the security mode, the system controller records the security identification signal in the area other than the user data area of the optical disk, as well as recording user data by means of converting an address through use of a password. At the time of reproduction of data, absence or presence of the security identification signal is ascertained. When the security identification signal is present, the address is inversely converted, thereby reproducing data.

Data recorder having data encryption function and data reproducing device

A disk drive and an information processing system optimizes the number of rotations of a disk. Data read from a disk and previously-read cache data are temporarily stored in buffer memory. When a total amount of cache data achieved during a given period of time Tor an average amount of the same is equal to or less than a threshold value X, a system controller controls the number of rotations in an increasing manner, thereby optimizing the number of rotations. When a total amount of cache data achieved during a given period of time T(TT) or an average amount of the same is equal to or greater than a threshold value X, a system controller controls the number of rotations in an decreasing manner, thereby optimizing the number of rotations.

Disk drive and information processing system having the same

A disk inspection apparatus for discriminating disks. The disk inspection apparatus has an ECC control section and a comparison section. The ECC control section measures the number of error corrections PIE and the number of error correction failures PIF in a predetermined section of the disk. The comparison section discriminates the disk as a disk with a deterioration in jitter characteristic when the minimum or the average of the PIE exceeds a first threshold value; discriminates the disk as a normal disk when the maximum of the PIF is equal to or smaller than a second threshold and the minimum or the average of the PIE is equal to or smaller than the first threshold value; and discriminates the disk as a scratched disk when the minimum or the average of the PIE is equal to or smaller than the first threshold value and the maximum of the PIF exceeds the second threshold value.

Disk inspection apparatus

An optical disk apparatus for recording test data onto an optical disk while changing the level of recording power and determines the optimum recording power with reference to the quality of a reproduced signal of the test data. A modulation degree or a &#x3b3; value is calculated from a reproduced signal of the test data, and the gradient of a change of the modulation degree or the &#x3b3; value relative to the recording power Pw is calculated. Further, a target recording power is determined utilizing an area where the gradient of the change is relatively sharp, and the optimum recording power is determined based on the target recording power.

Optical disk apparatus

An optical disk device for writing data onto an optical disk having a wobble track comprises an optical pickup for irradiating laser light of a writing power and laser light of a replaying power onto an optical disk and for converting return light from the optical disk into an electrical signal, a filter for extracting a wobble component contained in the return light signal when the laser of a writing power is irradiated, a processor for detecting the direction of track deviation based on the phase of the wobble component, and an actuator for driving the optical pickup in the width direction of the track based on the direction of the track deviation in order to control the tracking. Because the phase of the wobble component differs for a case when a light spot is deviated radially inward and for a case when a light spot is deviated radially outward, the direction of the track deviation can be detected based on the phase of the wobble component and the tracking can be controlled during data writing.

Optical disk device

An optical disk unit for recording information on and reproducing information from a disk recording medium by projecting a light beam thereonto includes a signal level detection part detecting a level of a track error signal generated based on reflected light of the light beam from the disk recording medium, a scattered light detection part detecting scattering of the reflected light, and an off-track detection part which detects an off-track of the light beam using detection signals supplied from the signal level detection part and scattered light detection part.

Optical disk unit

An optical disk recording apparatus for recording information onto a write-once or erasable optical disk has a memory component including a table of prerecorded correction curves consisting of recording power correction values corresponding to radial positions for each type of a variety of different optical disks, a correction component for correcting the recording power in an optimum power control operation (OPC) operation using the appropriate correction value, and a recording component for recording information onto the optical disk using the corrected recording power.

Optical recording apparatus for recording information on a write-once disk or an erasable optical disk

A three-phase motor having three Hall-effect devices for production of as many rotor position signals for use in excitation control of its windings, the signals being indicative of the angular position of the motor rotor with respect to the stator and having phase differences of 120 degrees. A motor speed control system is disclosed which utilizes the rotor position signals for detection of the actual running speed of the motor. Included are differentiating circuits connected one to each Hall-effect device for producing outputs in prescribed phase relationship with the rotor position signals. Connected to the differentiating circuits, switching transistors are controlled by binary switch control signals derived from the rotor position signals, passing the positive half-waves, or approximately positive half-waves, of the differentiating circuit outputs. The thus-obtained half-waves are then added together into a motor speed signal representative of the actual running speed of the motor. This signal is subsequently compared with a target speed signal indicative of a desired running speed of the motor, and the difference, if any, therebetween is fed as a speed control signal into a motor excitation circuit, which responds to both the rotor position signals and the speed control signal for exciting the motor windings for rotation at the desired speed.

Speed control of a motor

The present invention provides a focusing and tracking servo circuit used in an optical disk device that can maintain stability of the focusing and tracking servo at a time of recording or reproduction. This focusing and tracking servo circuit includes: a first storage unit that stores a parameter corresponding to light beam power at a time of recording; a second storage unit that stores a parameter corresponding to light beam power at a time of reproduction; and a selector unit that selects from the parameters stored in the first and second storage units upon switching between recording and reproduction, and sets the selected parameters in a detector unit. With this structure, the parameters can be instantly switched at the same time as the switching between recording and reproduction, and the stability of the focusing and tracking servo can be maintained.

Focusing and tracking servo circuit in an optical disk device

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.

Method and apparatus for checking the quality of CD-ROMS or the like for reading them at matching speeds

CD-ROMS of more or less poor quality, such as those having eccentric center holes or uneven weight distributions circumferentially, tend to overload tracking and focusing servos and hence to invite read errors and retries. Each CD-ROM on being loaded into a CD-ROM drive is therefore checked as to its quality preparatory to reading. Either or both of the servos may fail to keep the read beam under control if the disk is not of good quality. Such unlocking of either or both servos is detected in terms of the number of transducer output pulses, the magnitude of transducer output voltage, or the number of read errors, during a complete disk revolution. Disk quality is first checked at four times the standard audio CD speed, then at eight times that speed, and finally at twelve times that speed. Disks of poor quality are read at two times the standard audio CD speed, those of below-average quality at four times that speed, those of above-average quality at eight times that speed, and those of good quality at twelve times that speed.

Method and apparatus for high speed data recovery from CD-ROMs or like

Method and apparatus for checking the quality of CD-ROMs or the like for

Method and apparatus for high speed data recovery from CD-ROMS or like

A CD-ROM drive is disclosed which usually is put to use with CR-ROMs of varying qualities which may, or may not, wobble during rotation, possibly resulting in the vibration of the complete device. On being loaded into the device, therefore, each disk is rotated at increasing speed preparatory to reading. The speed of disk rotation at which vibration due to disk wobbling builds up to a prescribed limit is held as a maximum allowable speed until the disk is unloaded. The disk is subsequently read at no more than the maximum allowable speed.

Growing community of inventors

Tachikawa, Japan

Mitsumasa Kubo