Sony Corporation

Shinichi Yamamura

Yoichiro Sako

Tamotsu Yamagami

Toru Takeda

Katsuhiro Seo

Masayuki Arai

Akira Shimazu

An optical reproducing apparatus according to the present invention includes a land/groove switching circuit for alternately switching reproduction of a record mark on a groove portion and a land portion. This allows a tracking operation to be carried out continuously at a connection point to a subsequent track in the recording direction without a laser beam from an optical pickup passing through an end of a spiral track. A recording medium according to the present invention includes a recording track formed of a groove portion and a land portion, and a record mark used for switching a tracking operation so that a light beam emitted from the optical pickup should be irradiated alternately on the groove portion and the land portion. When the record mark is detected, a track jump operation is carried out, and information is reproduced from the groove portion and the land portion alternately.

Recording medium having track formed of land portion and groove portion,

An error-correcting method and apparatus for a block of data provided with an error-correcting parity for error correction and an error-checking parity that can be used to generate a syndrome for error-checking, in which error correction is carried out by the use of the error-correcting parity and then an error check is carried out by the use of the error-checking parity thereby to increase the reliability of the error-checking data, wherein error information produced by the error-correction process using the error-correcting parity is utilized to correct the syndrome used in the error-checking process, so as to execute the respective operations in parallel and reduce the required data processing time or through-put.

Method and apparatus for error correction

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.

Optical disc recording method and apparatus for digital data having a

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.

Data transmission method suitable for a disc

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. Essentially the reverse operation takes place upon reproduction of the recorded signals.

Apparatus for recording and reproducing data

A rectangular array is formed by a predetermined amount of data and an error detecting code that detects a possible error contained in the data. Each error correcting code is formed from data in each of the row and column directions of the rectangular array and is added to the rectangular array to thereby provide a product code. When the product code is arranged, row data in each of the row directions of the rectangular array is supplied to an error correcting code generator which generates the error correcting codes in sequence. At the same time, the respective data is supplied sequentially to the error detecting code generator and thereby a unique error detecting code is generated. When the decoding is carried out by using the error correcting code, the error correcting process is ended in response to the acceptance of a data request signal and then, the presence or absence of a data error in the error corrected data is checked by using the error detecting code. When the data error is not detected, that data is delivered.

Generator for an error correcting code, a decoder therefore, and a

In an error correcting method for a block of data having first and second error correction codes based on first and second series of symbols within the data block, error correction is performed repeatedly by alternately using the first and second code series, to achieve the maximum error correcting capability, without reference to the result of a previous error correction using the other series.

Error correction method

A circuit for detecting existence of an information signal comprising an input circuit provided for supply with the information signal, a clamp circuit for clamping a signal obtained from the input circuit to a predetermined fixed DC level, a level detector for detecting the amplitude level of an output of the clamp circuit and for producing a DC output with its level corresponding to the detected amplitude level, and a level comparator for comparing the DC output from the level detector with a predetermined reference voltage to produce an output signal assuming a first level when the DC output is higher than the reference voltage and a second level when the DC output is lower than the reference voltage. The first level or second level of the output signal from the level comparator indicates that the information signal is supplied to the input circuit.

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Tokyo, Japan

Shinichi Yamamura