Abstract: An optical disc using a single-spiral land and groove track format and an address signal enabling simple sector address management and format compatibility with read-only optical disc media is disclosed. Four physical address areas PID1-PID4 are recorded to a header area such that PID1 and PID2 are offset one-half track pitch toward the outside circumference of the disc from the groove track center, and PID3 and PID4 are offset one-half track pitch toward the inside circumference of the disc from the groove track center, and the header area is shared by groove track sectors and land track sectors. A groove track sector address is written to PID3 and PID4, and the sector address of the land track sector adjacent on the outside circumference side of that groove sector is written to PID1 and PID2. The address of each sector increases 1 in the same sequence as the sectors are formed in the recording spiral.

Abstract: A method for encoding a picture based on an intra-picture coding and an inter-picture prediction coding having an absolute value of a maximum range of motion compensation between continuous pictures in terms of time being H pixels (H: a positive integer) in a first direction and V pixels (V: a positive integer) in a second direction, the method includes the steps of: receiving a picture and judging whether the picture is directly/indirectly referred to by a further picture among the continuous pictures in terms of time or not; determining a maximum distance L (L: a positive integer) between the picture and the further picture directly/indirectly referring to the picture; dividing the picture into a first to an Nth sub-pictures (N: an integer equal to or larger than 2), a size of the first to the Nth sub-pictures being larger by at least L.times.V pixels in the first direction or at least L.times.

Abstract: An optical disk of the present invention has one or more recording tracks formed concentrically or spirally on the disk to which data signals are recorded by forming different-length marks and spaces on the tracks. An ID signal combining marks and spaces of two or more predetermined lengths approximately equal to the length of the marks and spaces forming the data signals is recorded to the recording tracks within a predetermined disk area, thus creating the ID signal by aligning the marks and spaces in the radial direction and recording the aligned marks and spaces to adjacent tracks in a predetermined radial disk area. Also, a reproduction apparatus for reproducing signals from the optical disk is disclosed.

Abstract: An information recording apparatus for continuously recording information without losing any information even if the apparatus temporarily falls into a recording-disable state owing to the shock externally applied, etc. is provided. A disability detector for detecting the recording-disable state is provided in the information recording apparatus, thereby interrupting the recording operation and the reading operation from the buffer memory under the recording-disable state, and making a coding rate reduction controller instruct a coder to temporarily reduce the coding rate of the input information. A remaining capacity detector is provided for monitoring the remaining capacity in the buffer memory and instructing the coder to temporarily reduce the coding rate of the input information when the remaining capacity becomes a predetermined value or less. As a result, the reduction in the remaining capacity of the buffer memory under the recording-disable state is prevented.

Abstract: A digital information playback apparatus comprises A/D converter that converts a playback signal into digital data, a maximum likelihood decoder that decodes the quantized data output from the A/D converter to obtain the original digital information, and a timing signal extractor that generates a sampling clock used in the A/D converter, and wherein the maximum likelihood decoder detects the response characteristic of the record/playback system and obtains level fluctuations contained in the playback signal, based on the survival path obtained as a maximum likelihood decoding result, to control the expected multilevel equalized values used in the maximum likelihood decoder, the timing signal extractor obtains level fluctuations, based on the survival path obtained as a maximum likelihood decoding result, and obtains the component of the level fluctuations due to phase shifts of the sampling clock of the VCO to control the phase of the sampling clock of the VCO.

Abstract: A disk medium is a video disk, being an optical recording medium possessing concentric or spiral tracks, in which one track is divided into P sectors, and group mark signals are recorded in every Q sectors.

Abstract: In recording data on a rewritable optical disk with a mark edge recording method, the occurrence of edge shift is compensated for. As a first power of a laser beam is greater than a second power, start and termination ends of each mark are produced by irradiation of the first power and a remaining intermediate portion of the mark is produced by irradiating the first and second powers alternately at equal intervals of a predetermined duration which is shorter than a period of a clock pulse. Also, the start and termination ends of the mark are specifically dislocated corresponding to a length of the mark and lengths of two neighbor spaces before and after the mark.

Abstract: In an apparatus for recording data on a rewritable optical disk with a mark edge recording the occurrence of edge shift is compensated for. As a first power of a laser beam is greater than a second power, start and termination ends of each mark are produced by irradiation of the first power and a remaining intermediate portion of the mark is produced by irradiating the first and second powers alternately at equal intervals of a predetermined duration which is shorter than a period of a clock pulse. Also, the start and termination ends of the mark are specifically dislocated corresponding to a length of the mark and lengths of two neighbor spaces before and after the mark.

Abstract: A disc reproducing apparatus for reproducing data stored on plural disc surfaces at a constant linear density comprises: plural heads for reproducing the data on the plural disc surfaces at the same time respectively; a controller for controlling positions of the heads such that a total data rate of data reproduced form the plural heads is constant, each of the disc surfaces being divided into N circumference zones; N signal processing circuits, having N processing speeds corresponding to N data rates corresponding to the N circumference zones, for processing the reproduced data respectively; a switch for supplying the reproduced data to the N signal processing circuits such that data reproduced by each of the plural heads is supplied to any of the N signal processing circuits suitable for the data rate of the supplied data thereto; and a combining circuit for combining the processed data signals from the N signal processing circuits into a combined serial data signal of which data rate corresponds to the tot

Abstract: An analog-to-digital converter executes analog-to-digital conversion of a first analog video signal at a predetermined sampling frequency "fs". A time base converter converts a time base of an output signal from the analog-to-digital converter at a predetermined time base conversion frequency "ftci". A digital output signal from the time base converter is converted into a corresponding second analog video signal in response to a clock signal of a frequency corresponding to the frequency "ftci". The second analog video signal is converted into an FM video signal recorded on a video region of an optical disk. A binary audio digital signal is converted into a multi-level form digital audio signal. The binary audio digital signal has a data rate corresponding to the frequency "ftci". The multi-level form digital audio signal has a data rate "ftci/n" and 2.sup.n discrete amplitude levels where "n" denotes a predetermined integer.

Abstract: In a clock generator circuit, a zero hold circuit produces from a fixed clock signal a zero hold clock signal which is in phase with an external sync signal. A phase comparator circuit produces phase difference data indicating the phase difference between the external sync signal and an internal sync signal. A counter cleared by the external sync signal counts pulses of the zero hold clock signal to obtain count data. A memory receiving the phase difference data and the count data as its address input produces the internal sync signal when the count data is smaller than the number of pulses in one cycle of the external sync signal having no time-base variations, and a phase control signal determined by the phase difference data and the count data. A phase shifter shifts the phase of the zero hold clock according to the phase control signal to obtain a modified clock signal synchronized with the external sync signal.

Abstract: A video disc is produced from a master video disc which has recorded therein a video signal including a synchronous signals occurring periodically and divided into plural channels by the cycle of the synchronous signals. The plural channel signals are recorded on a group of plural tracks, respectively. In the case of reproducing the video disc, the plural channel signals are reproduced from the group of plural tracks, respectively. Synchronous signals are detected from the reproduced signals. The reproduced channel signals in a period of the synchronous signal are stored in plural memories based on the synchronous signals detected. The stored plural channel signals are continuously reproduced by successively reading from the memories of channels by switching at synchronous intervals. The signal bandwidth of the channels becomes 1/n of the original video signal by recording and reproducing the video signal by dividing it into plural channels(n channels) in such manner.

Abstract: A synchronous signal generator for use with the MUSE signal in the MUSE system which is a high definition television systems. A PLL circuit including a phase comparator and a voltage-controlled oscillator and a counter, is used to generate a system clock synchronized with an external clock. A frame synchronizing signal detected through a frame sychronization detection circuit from an inputted digital MUSE signal frame-resets the counter through a window circuit. The frame synchronization is established at an accuracy of a set range of the window circuit. Also, in this case, if the sychronization deviates on a clock by clock basis, a sampling phase error from a phase error computing circuit is monitored by a comparator circuit so that a deviation in the synchronization can be detected. When the synchronization deviates, by horizonally resetting the counter, the clock synchronization can be established.

Abstract: In reproduction of signal recorded on an optical disk by irradiation of laser light beam thereon, interference between reflected diffracted light of +1th order or -1th order and reflected diffracted light of 0th order is coersively induced, and by detecting the interference light, a high frequency signal can be reproduced.

Abstract: A method of reproducing signals formed in slant surfaces of a V-shaped track groove formed in an optical disk. The beam reflected from each slant surface has a portion having a small crosstalk component and a portion having a large crosstalk component, the portions existing separately. The beam reflected from the V-shaped track groove is detected by a photodetector which is composed of two photodetector units. Thus, the output from the first photodetector unit has a small crosstalk component, while the output from the second photodetector unit has a large crosstalk component. The reproduced signal is obtained by subtracting, from a signal formed by amplifying the output of the first photodetector unit, a signal formed by amplifying the output of the second photodetector unit, so that the crosstalk component in the signal from the first photodetector unit is negated by the crosstalk component in the signal from the second photodetector unit, so that the reproduced signal can have a reduced crosstalk component.

Abstract: An optical disk having V-shaped grooves with depths periodically varied at a frequency f for every two grooves, thus realizing a large recording area on each slant of the grooves. A tracking method for the optical disk in which two laser spots irradiate two adjoining slants of a V-shape groove, and pilot signals are made of components of the frequency f which are detected from the reflected beams of the respective two laser spots on the optical disk, and whereby the tracking is performed by controlling so as to make the magnitudes of the two pilot signals become equal to each other.

Abstract: In an optical disk having grooves, pits representing reference signals in header regions of the grooves are disposed to be spaced apart from each other in a longitudinal direction of the groove to suppress undesirable interference or crosstalk of the reference signals in adjacent V-grooves. In the reproduction of such reference signals, two laser beam spots are respectively irradiated on the first and second oblique surface tracks in the V-groove. Two electric signals made by detecting the light reflected from the spots are examined to determine whether they are in coincidence. When coincidence is confirmed, the signals are used as valid reference signals.