# US 5,347,408 A · Magnetic recording and reproducing method and apparatus with vertical magnetization component reduction > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,347,408 A - Document ID: US5347408A - Status: Granted - Kind: A - Application number: 07/828,137 - Filed: 1992-01-30 - Granted: 1994-09-13 - Earliest claimed: 1991-02-07 - Assignees: Canon Kabushiki Kaisha - Inventors: Makoto Gohda; Shinichi Yamashita; Yasuyuki Tanaka - Web page: https://patentgrep.com/patent/US5347408A ## CPC - G11B 5/85: Coating a support with a magnetic layer by vapour deposition - G11B 5/09: Digital recording - G11B 5/674: {having differing macroscopic or microscopic structures, e.g. differing crystalline lattices, varying atomic structures or differing roughnesses} - G11B 20/10009: {Improvement or modification of read or write signals} - Y10S 428/928: Magnetic property - Y10T 428/12465: having magnetic properties, or preformed fiber orientation coordinate with shape - 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) - Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract A digital signal to be recorded is converted into a digital signal having a suppressed low-frequency spectrum and having a shortest recording wavelength greater than half an original shortest recording wavelength, and the converted digital signal is recorded on a magnetic recording medium in which a plurality of metal evaporated films having different crystal-growth directions are laminated. The digital signal is reproduced from the magnetic recording medium in which the plurality of metal evaporated films having different crystal-growth directions are laminated. Waveform equalization is performed on the reproduced digital signal, and integration detection is performed on the waveform-equalized digital signal, thereby restoring an original digital signal. ## Claims ### Claim 1 A magnetic recording method comprising the steps of: converting a digital signal to be recorded into a digital signal having a suppressed low-frequency spectrum and having a shortest recording wavelength greater than half an original shortest recording wavelength; and recording the converted digital signal on a magnetic recording medium in which a plurality of metal evaporated films having different crystal-growth directions are laminated, wherein magnetization components of the plurality of metal evaporated films of said magnetic recording medium in a vertical direction to a surface thereof are substantially zero in total. ### Claim 2 (depends on 1) A method according to claim 1, wherein the plurality of metal evaporated films are an even number of metal evaporated films, crystal-growth directions in adjacent ones of the metal evaporated films being opposite to each other with respect to a surface of the magnetic recording medium and making substantially the same angle with respect to the surface of the magnetic recording medium. ### Claim 3 (depends on 1) A method according to claim 1, wherein the plurality of metal evaporated films are an odd number of metal evaporated films which are not less than three metal evaporated films, crystal-growth directions in adjacent ones of the metal evaporated films being opposite to each other with respect to a surface of the magnetic recording medium, and an angle which a crystal-growth direction in an odd-numbered metal evaporated film makes with the surface of the magnetic recording medium being smaller than an angle which a crystal-growth direction in an even-numbered metal evaporated film makes with the surface of the magnetic recording medium. ### Claim 4 A magnetic reproducing method comprising the steps of: reproducing a digital signal from a magnetic recording medium in which a plurality of metal evaporated films having different crystal-growth directions are laminated, wherein magnetization components of the plurality of metal evaporated films of said magnetic recording medium in a vertical direction relative to a surface thereof are substantially zero in total; performing waveform equalization on the reproduced digital signal; and performing integration detection on the waveform-equalized digital signal to restore an original digital signal. ### Claim 5 (depends on 4) A method according to claim 4, wherein the plurality of metal evaporated films are an even number of metal evaporated films, crystal-growth directions in adjacent ones of the metal evaporated films being opposite to each other with respect to a surface of the magnetic recording medium and making substantially the same angle with respect to the surface of the magnetic recording medium. ### Claim 6 (depends on 4) A method according to claim 4, wherein the plurality of metal evaporated films are an odd number of metal evaporated films which are not less than three metal evaporated films, crystal-growth directions in adjacent ones of the metal evaporated films being opposite to each other with respect to a surface of the magnetic recording medium, and an angle which a crystal-growth direction in an odd-numbered metal evaporated film makes with the surface of the magnetic recording medium being smaller than an angle which a crystal-growth direction in an even-numbered metal evaporated film makes with the surface of the magnetic recording medium. ### Claim 7 A magnetic recording and reproducing method comprising the steps of: converting a digital signal to be recorded into a digital signal having a suppressed low-frequency spectrum; recording the converted digital signal on a magnetic recording medium in which a plurality of metal evaporated films having different crystal-growth directions are laminated, wherein magnetization components of the plurality of metal evaporated films of said magnetic recording medium in a vertical direction relative to a surface thereof are substantially zero in total; reproducing the digital signal from the magnetic recording medium; performing waveform equalization on the reproduced digital signal; and performing integration detection on the waveform-equalized digital signal to restore an original digital signal. ### Claim 8 A magnetic recording apparatus comprising: (a) inputting means for receiving a digital signal as its input; (b) converting means for converting the digital signal inputted from said inputting means into a digital signal having a suppressed low-frequency spectrum; and (c) recording means for recording the digital signal outputted from said converting means on a magnetic recording medium in which a plurality of metal evaporated films having different crystal-growth directions are laminated, wherein magnetization components of the plurality of metal evaporated films of said magnetic recording medium in a vertical direction relative to a surface thereof are substantially zero in total. ### Claim 9 A magnetic reproducing apparatus comprising: (a) reproducing means for reproducing a digital signal from a magnetic recording medium in which a plurality of metal evaporated films having different crystal-growth directions are laminated, wherein magnetization components of the plurality of metal evaporated films of said magnetic recording medium in a vertical direction relative to a surface thereof are substantially zero in total; (b) waveform equalization means for performing waveform equalization on the reproduced digital signal; and (c) integration detection means for performing integration detection on the waveform-equalized digital signal to restore an original digital signal. ### Claim 10 A magnetic recording and reproducing apparatus comprising: (a) inputting means for receiving a digital signal as its input; (b) converting means for converting the digital signal inputted from said inputting means into a digital signal having a suppressed low-frequency spectrum; (c) recording means for recording the digital signal outputted from said converting means on a magnetic recording medium in which a plurality of metal evaporated films having different crystal-growth directions are laminated, wherein magnetization components of the plurality of metal evaporated films of said magnetic recording medium in a vertical direction relative to a surface thereof are substantially zero in total; (d) reproducing means for reproducing the digital signal from the magnetic recording medium; (e) waveform equalization means for performing waveform equalization on the reproduced digital signal; and (f) integration detection means for performing integration detection on the waveform-equalized digital signal to restore an original digital signal.