Abstract: In an optical disk driving apparatus using an optical disk, a sector address in a set address sequence is sequentially provided in a pre-format in an address recognizing section of each sector. The driving apparatus has a reader for reading the sector address provided in the pre-format out of the optical disk; an error detector for detecting an error in sector address read by the reader; and a device for setting a value of the read sector address as sector address data when there is no error in the read sector address. The setting device sets a value of the next sector address as the sector address data on the basis of the set address sequence from data of a sector address just before the read sector address when there is the error in the read sector address. The driving apparatus is constructed such that data are written and read out of the optical disk based on the sector address data.

Abstract: An optical disc apparatus for use with an optical disc including on its tracks pairs of servo pattern areas to be recorded with an address pit pattern by using data patterns, each of which indicates a relative track number of the recording track, being repeated in a predetermined cycle; the servo area comprising a pair of wobble pits each being disposed off the center of the recording track in opposite direction with one another, a clock pit disposed on the center of the track and address pit pattern consisting of a plurality of pits disposed on the center of the recording track for indicating relative track number;an optical pick-up device;a relative address detection means to identify the relative track number of the track to which the optical pick-up is accessing and for outputting detected relative address signal; andan address/speed detection means for receiving the relative address signal outputted by the relative address detection means, and detecting an absolute track number of the track to which the

Abstract: A tracking servo method in an optical disk drive unit has the steps of providing a signal in accordance with a different in voltage level between two signals respectively reproduced from a pair of tracking sample flags arranged in positions shifted by predetermined distances from a tracking center on an optical disk; setting the signal in accordance with the voltage level difference to a tracking error signal; and positioning a light spot on the optical disk in the tracking center using the tracking error signal. The tracking servo method further has the step of normalizing the tracking error signal by a signal indicative of a difference between an average value of the two reproducing signals and a signal reproduced from a sample flag approximately arranged in the tracking center on the optical disk.

Abstract: In a data modulating system, 12 bits of input data correspond to 15 channel bits of an output code. The input data of 12 bits are converted to the output code of 15 channel bits such that 7 channel bits in the output code provide code "1". The output code of 15 channel bits is divided into a first group of 7 channel bits and a second group of 8 channel bits. The number of bits in the first group providing code "1" the number of bits in the second group providing code "1" are respectively at 3 and 4, 4 and 3, or 2 and 5.

Abstract: A control system is provided for an optical disk driving apparatus adapted to rotate an optical disk having a plurality of tracks, and which is adapted, during the rotation of the disk, to perform optical recording and/or reproduction of information for a track which has been accessed with a light beam. The control system changes the speed f of recording/reproduction of information in accordance with the radius r of a track to be accessed in such a manner that the tracks are divided into a plurality of concentric annular blocks each having different approximate radii, and the same speed f of the recording/reproduction of information is allocated to the tracks in the same block but different speeds f of recording and/or reproduction of information are allocated to the respective blocks.

Abstract: An optical pickup device for an optical recording disk having an information recording surface comprises an objective lens for converging a light beam emitted from a light source onto the information recording surface of the disk so as to form a beam spot thereon along an information track of the disk. At least one light detecting unit comprised of a plurality of photodetectors is provided for the detection of focus and tracking errors and the detection of the position of the optical axis of the objective lens. Each of the photodetectors is able to receive a light beam reflected by the information recording surface of the disk and to produce an output signal which is proportional to the amount of the light beam incident thereon.

Abstract: A PLL circuit comprises a phase comparator for inputting input and output clock signals and detecting a difference in phase between these both signals and outputting a signal based on the phase difference; a proportional circuit for converting the output signal based on the phase difference from the phase comparator to a first voltage approximately proportional to the phase difference; an integral circuit for converting the output signal based on the phase difference from one of the phase comparator and the proportional circuit to a second voltage approximately proportional to an integral value of the phase difference; and a voltage-controlled oscillator for inputting the first output voltage from the proportional circuit and the second output voltage from the integral circuit, and generating an output clock signal having a frequency controlled by the first and second output voltages.

Abstract: A tracking control system for use in an optical pick-up of an optical disc recording and reproducing apparatus includes a pair of photoelectric elements for receiving light reflecting from an optical disk. A pair of light current outputs obtained from the photoelectric elements is processed to produce a differential signal. A low pass filter is provided as a phase delay compensation circuit for compensating the low frequency component of the differential signal. During a track jump mode, the differential signal is processed through the low pass filter whose output is added with a kick pulse to produce a drive signal for use in a tracking actuator. The input side of the low pass filter may be disconnected during a track jump mode, thereby causing the low pass filter to also serve as a holding circuit for holding the voltage of the differential signal immediately prior to track jump.

Abstract: A tracking control system for controlling a relative positional relation between an optical pick-up and a rotating optical disc is provided. A tracking error signal is supplied to a low pass filter, to a lead phase compensating circuit and also to a zero cross comparator which supplies its output to a pulse generating circuit. During a normal tracking mode, in which the optical pick-up is maintained in alignment with a recording track of the rotating disc, an output from the low pass filter and an output from the lead phase compensating circuit are added to define a feed-back signal which is then supplied to the optical pick-up.

Abstract: A phase-locked loop filter applicable to a motor speed control of an optical disk apparatus and others counts a difference in phase between an input signal to a phase-locked loop and an output signal of the loop, integrates the resulting counts modulo a predetermined value which is dependent upon the period of a clock, produces an overflow signal every time an overflow occurs, and generates the output signal by dividing the frequency of the overflow signal.

Abstract: A motor speed control applicable to an optical disk device and others includes a frequency converter for digitally comparing the frequency of a target speed signal and that of an actual speed signal. The outputs of the frequency converter are individually applied to frequency-to-voltage converters one of which is associated with the target speed and the other with the actual speed.