Abstract: When a time-sequential signal such as an audio or digital data signal is optically recorded on a disc-shaped recording medium, the transmission rate of the digital data is determined or the time-sequential audio signal is sampled at a predetermined sampling frequency to obtain time-sequential digital data which is sequentially recorded on the disc-shaped recording medium. The rotational speed of the disc-shaped recording medium is controlled in response to the transmission rate of the time-sequential digital data.

Abstract: A data transmission method for data is disclosed in which a rectangular array is formed of a block of data containing n words, supplementary data necessary to transmit the n words of data and an error detecting code to detect possible errors which may occur in the block of data and the supplementary data. An error correcting code is produced for each row and column of data of the rectangular array and added thereto to thereby form a product-coded data, each data word of which is thereafter sequentially fetched and transmitted along each row of the product-coded data. When the block of data is changed from n data words to m data words, the number of data words in one direction of the rectangular array is fixed, while the number of data words in the other direction of the rectangular array is changed to m, to thereby form a new rectangular array which is also sequentially fetched and transmitted along each row of the array.

Abstract: A method and an apparatus for seeking a target address having an appended error check code are disclosed. According to the invention, when seeking a target address on a record medium on which the recorded data are divided into plural blocks in correlation with an address for each block and an error check code for each address, the error check code to be appended to the address is formed from the target address. The target address and the error check code derived from the target address are compared to the address having the error check code reproduced from the record medium. When the result of such comparison has revealed that the error is within the symbol or bit number that can be corrected by the error check code, the address read from the record medium is determined to be the target address.

Abstract: A recording and reproducing apparatus comprising a memory for storing input data to be recorded in units of a predetermined quantity, a first address control means for generating only sequential memory addresses, a second address control means for generating non-sequential memory addresses, and means for adding a redundant bit such as an error correcting code and so on to each predetermined quantity unit of data, wherein when the input data has no correlation with adjacent input data, the input data is sequentially written in the memory by the first address control means, read out therefrom, added with the redundant bit, and sequentially recorded on the recording medium without changing the order of the inputted data, while when the input data has a correlation with adjacent input data, the input data is written in the memory by the second address control means in scrambled form, read out therefrom, as scrambled, and then the scrambled data is added to the redundant bit and recorded on the recording medium.

Abstract: An optical disc recording and reproducing apparatus incorporates apparatus for recording a modulated signal on an optical disc, using a laser beam, and apparatus for optically reading a signal recorded on the disc. In both recording and reproducing modes, an optical signal is produced from the disc and used to supply a control signal to a servo system, for controlling the position of the laser beam relative to the optical disc. Apparatus is provided for subtracting, from the servo control signal, the low frequency components in the modulated signal being recorded on the disc, to improve the accuracy of focus and tracking of the laser beam relative to the optical disc.

Abstract: A signal recording and reproducing device for use with an opto-magnetic disk having a number of concentric recording tracks. An optical head sweeps a given track at least twice during a time interval equal to a predetermined reproduction time for the track. Erasure signals and recording signals are supplied to the optical head during the first time sweeping and the second time sweeping, respectively, in order to effect signal erasure and recording. At the time of switching from the first time sweeping to the second time sweeping, the address data indicating the end point written on the terminal portion of the previously recorded signal area are sensed, and the recording is effected from the thus sensed recording end point.

Abstract: A system for encoding a binary digital information signal comprised of 8-bit information words occurring within a frequency band to produce an encoded binary digital information signal comprised of 17-bit channel words formed of 14-bit information words and 3-bit separation words and with the encoded signal satisfying the d- and k-constraint rules, reducing DC imbalance and having substantially reduced components thereof in a predetermined undesirable lower frequency range of the frequency band, the system converting each 8-bit information word into a 14-bit information word; generating a set of four possible 3-bit separation words for use each 14-bit information word which satisfy the d- and k-constraint rules; determining an integrating transfer function characteristic having a high gain with respect to the predetermined frequency range; obtaining a step response by modifying each 14-bit information word and each respective possible 3-bit separation word by the integrating transfer function characteristic;

Abstract: A brushless DC motor having a rotor magnet magnetized to provide a sinusoidal magnetic field and two-phase stator windings at positions which differ from each other by an electrical angle which is an odd multiple of 90.degree. is provided with a drive circuit comprising a signal generator with an output having a frequency determined by the rotational speed of the rotor, and a memory having stored therein digital information data converted from sampled values of a sinusoidal signal free of distortion. The digital information data stored in the memory is read out therefrom by the output of the signal generator in synchronism with the magnetic field from the rotor magnet, and such read-out information data is employed to determine currents flowing through the stator windings so that torque ripple is substantially eliminated.