# US 5,347,517 A · Information processing apparatus > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,347,517 A - Document ID: US5347517A - Status: Granted - Kind: A - Application number: 08/117,656 - Filed: 1993-09-08 - Granted: 1994-09-13 - Earliest claimed: 1989-11-16 - Assignees: Canon Kabushiki Kaisha - Inventors: Seiichiro Satomura; Kano Takeshita - Web page: https://patentgrep.com/patent/US5347517A ## CPC - G11B 20/10222: {clock-related aspects, e.g. phase or frequency adjustment or bit synchronisation (dedicated sync patterns in the modulation code G11B20/1403)} - G11B 20/10009: {Improvement or modification of read or write signals} - G11B 20/1403: {characterised by the use of two levels} - G11B 20/18: Error detection or correction; Testing {, e.g. of drop-outs} - G11B 20/1883: {Methods for assignment of alternate areas for defective areas} - G11B 33/10: Indicating arrangements; Warning arrangements {(G11B15/04, G11B19/04, G11B27/34, G11B27/36 take precedence)} - G11B: INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER (recording measured values in a way that does not require playback through a transducer G01D9/00; recording or playback apparatus using mechanically marked tape, e.g. punched paper tape, or using unit records, e.g. punched or magnetically marked cards G06K; transferring data from one type of record carrier to another G06K1/18; circuits for coupling output of reproducer to radio receiver H04B1/20; gramophone pick-ups or like acoustic electromechanical transducers or circuits therefor H04R) ## Abstract An information processing apparatus having the function of reproducing digital information recorded on a recording medium has binarizing circuit for transforming a reproduction signal read from the recording medium into a binary signal, circuit for making from the binary signal a bit synchronous signal for use when the binary signal is demodulated, circuit for detecting the inverted portion of the binary signal by a periodical window of a predetermined period and producing a synchronous binary signal synchronized with the bit synchronous signal in accordance with the result of the detection, demodulating circuit for demodulating the digital information on the recording medium on the basis of the synchronous binary signal, and circuit for varying the period of the window in conformity with the situation. According to the above method, any small defect likely to develop into an error in the future is effectively detected to thereby obviate such a situation that the detection of a synchronous pattern becomes impossible or the reproduction of data becomes impossible. ## Claims ### Claim 1 An information processing apparatus having a function of reproducing digital information recorded on a recording medium, said apparatus comprising: binarizing means for transforming a reproduction signal read from the recording medium into a binary signal; means for forming from the binary signal a bit synchronous signal for use when the digital information is decoded; means for detecting an inverted portion of the binary signal with a window of a predetermined period set on the basis of the bit synchronous signal and for producing a synchronous binary signal synchronized with the bit synchronous signal is accordance with a result of the detection; decoding means for decoding the digital information on the recording medium on the basis of the synchronous binary signal and the bit synchronous signal; and means for widening the period of the window when reproduction of the digital information is impossible during normal reproduction. ### Claim 2 (depends on 1) An information processing apparatus according to claim 1, further comprising window forming means for forming the window, said window forming means comprising a plurality of window forming means having different window periods, said varying means selecting one of said plurality of window forming means to whereby vary the window period. ### Claim 3 (depends on 1) An information processing apparatus according to claim 1, wherein said varying means varies the period of the window during recording verifying check-up after data recording onto the recording medium. ### Claim 4 (depends on 3) An information processing apparatus according to claim 3, wherein the period of the window during the recording verifying check-up is narrower than the period of the window during ordinary reproduction. ### Claim 5 An information processing apparatus having a function of reproducing digital information recorded on a recording medium, said apparatus comprising: binarizing means for transferring a reproduction signal read from the recording medium into a binary signal; means for forming from the binary signal a bit synchronous signal for use when the digital information is decoded; means for detecting an inverted portion of the binary signal with a window of a predetermined period set on the basis of the bit synchronous signal and for producing a synchronous binary signal synchronized with the bit synchronous signal in accordance with a result of the detection; decoding means for decoding the digital information on the recording medium on the basis of the synchronous binary signal and the bit synchronous signal; means for varying the period of the window; and error correction means for correcting an error of the binary signal, wherein said varying means varies the period of the window in accordance with a result of the error correction by said error correction means, and wherein said varying means widens the period of the window in conformity with an increase in a number of error corrections or the success or failure of error correction. ### Claim 6 (depends on 5) An information processing apparatus according to claim 5, wherein when a number of error corrections by said error correction means is greater than a predetermined value or when error correction is impossible, the digital information is reproduced with the period of the window widened by said varying means and the reproduced digital information is re-recorded at a position discrete from the position on the recording medium at which reading has been effected. ### Claim 7 (depends on 5) An information processing apparatus according to claim 5, wherein when a number of error corrections by said error correction means is greater than a predetermined value or when error correction is impossible, the digital information is reproduced with the period of the window widened by said varying means and a warning is given to a user. ### Claim 8 An information processing apparatus having a function of reproducing digital information recorded on a recording medium, said apparatus comprising: binarizing means for transforming a reproduction signal read from the recording medium into a binary signal; means for forming from the binary signal a bit synchronous signal for use when the digital information is decoded; means for detecting an inverted position of the binary signal with a window of a predetermined period set on the basis of the bit synchronous signal and for producing a synchronous binary signal synchronized with the bit synchronous signal in accordance with a result of the detection; decoding means for decoding the digital information on the recording medium on the basis of the synchronous binary signal and the bit synchronous signal; and means for varying the period of the window, wherein the digital information includes pattern synchronous information, and said varying means varies the period of the window when the pattern synchronous information is read out from the recording medium, and wherein said varying means makes the period of the window narrower than that during ordinary reproduction when the pattern synchronous information is read out from the recording medium. ### Claim 9 (depends on 8) An information processing apparatus according to claim 8, wherein said varying means varies the period of the window during recording verifying check-up after data recording onto the recording medium. ### Claim 10 (depends on 8) An information processing apparatus according to claim 8, further comprising error correction means for correcting an error of the binary signal and wherein said varying means varies the period of the window when the pattern synchronous information is read out, in accordance with a result of the error correction by said error correction means. ### Claim 11 (depends on 10) An information processing apparatus according to claim 10, wherein said varying means varies the period of the window when the pattern synchronous information is read out, in conformity with an increase in a number of error corrections or a success or failure of error correction. ### Claim 12 (depends on 11) An information processing apparatus according to claim 11, wherein said varying means widens the period of the window when the pattern synchronous information is read out in conformity with an increase in the number of error corrections or the success or failure of error correction. ### Claim 13 (depends on 10) An information processing apparatus according to claim 10, wherein when a number of error corrections by said error correction means is greater than a predetermined value or when error correction is impossible, the digital information is reproduced with the period of the window when the pattern synchronous information is read out widened by said varying means and the reproduced digital information is re-recorded at a position discrete from the position on the recording medium at which reading has been effected. ### Claim 14 (depends on 10) An information processing apparatus according to claim 10, wherein when a number of error corrections by said error correction means is greater than a predetermined value or when error correction is impossible, the digital information is reproduced with the period of the window when the pattern synchronous information is read out widened by said varying means and warning is given to a user.