# US 5,706,267 A · Method and apparatus for retrieving data from a storage device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,706,267 A - Document ID: US5706267A - Status: Granted - Kind: A - Application number: 08/482,997 - Filed: 1995-06-07 - Granted: 1998-01-06 - Earliest claimed: 1994-05-06 - Assignees: Discovision Associates - Inventors: Noboru Kimura; Wen-Yung Yeh - Web page: https://patentgrep.com/patent/US5706267A ## CPC - G11B 20/10203: {baseline correction (DC correction by choosing codewords of the modulation code G11B20/1426)} - G11B 7/0037: with discs - G11B 7/0045: Recording (G11B7/006, G11B7/0065 take precedence) - G11B 7/005: Reproducing (G11B7/0065 takes precedence) - G11B 11/10504: {Recording (for shaping of magnetic domains G11B11/10528, for compensation of shift G11B11/1053)} - G11B 11/10515: {Reproducing (compensating pit shift G11B11/1053)} - G11B 11/10597: {Adaptations for transducing various formats on the same or different carriers} - G11B 20/10009: {Improvement or modification of read or write signals} - G11B 20/10314: {amplitude of the recorded or reproduced signal} - H03K 5/003: Changing the DC level (reinsertion of DC component of a television signal H04N5/16) - H03K 5/082: {with an adaptive threshold} - G11B 7/013: for discrete information, i.e. where each information unit is stored in a distinct discrete location {, e.g. digital information formats within a data block or sector} - G11B 20/1426: {conversion to or from block codes or representations thereof} - 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) - H03K: PULSE TECHNIQUE (measuring pulse characteristics G01R; modulating sinusoidal oscillations with pulses H03C; transmission of digital information H04L; discriminator circuits detecting phase difference between two signals by counting or integrating cycles of oscillation H03D3/04; automatic control, starting, synchronisation or stabilisation of generators of electronic oscillations or pulses where the type of generator is irrelevant or unspecified H03L; coding, decoding or code conversion, in general H03M) ## Abstract An apparatus and method for retrieving densely stored data from various types of magnetic media. A medium is scanned to provide an input signal. The input signal is conditioned through differentiation, equalization and partial integration. Positive and negative signal peak detectors are connected to the conditioned signal, and a threshold signal is generating corresponding to an average or midpoint of the measured positive and negative signal peaks. An output signal is generated by comparing the conditioned signal and the threshold signal. The DC component of the input signal is accounted for by feeding back the output signal and adjusting the threshold signal based on the duty cycle of the output signal. ## Claims ### Claim 1 An apparatus for retrieving data stored on a medium, said apparatus comprising: means for reading said stored data and generating a signal corresponding to said stored data; a differentiation stage for processing said signal prior to partial integration thereof; a partial integrator for receiving said signal; a threshold generator connected to said partial integrator; a data generator connected to said partial integrator and to said threshold generator, said data generator including a comparator; and a feedback path from said comparator to said threshold generator. ### Claim 2 (depends on 1) The apparatus according to claim 1 wherein said means for reading said stored data includes a differentiator. ### Claim 3 (depends on 1) The apparatus according to claim 1 wherein said medium includes a magneto-optical disk. ### Claim 4 (depends on 1) The apparatus according to claim 1 wherein said threshold generator generates a threshold signal which varies with a DC component of said signal. ### Claim 5 (depends on 4) The apparatus according to claim 4 wherein said threshold signal corresponds to an approximate midpoint of said signal. ### Claim 6 (depends on 1) The apparatus according to claim 1 wherein said comparator is connected to an output from said threshold generator and an output of said partial integrator. ### Claim 7 (depends on 1) The apparatus according to claim 1 wherein said partial integrator comprises: an integrator for receiving and processing said signal; a bandpass filter receiving and processing said signal; and a subtractor connected to an output of said integrator and an output of said bandpass filter. ### Claim 8 (depends on 7) The apparatus according to claims 7 further including a low pass filter connected to an output of said subtractor. ### Claim 9 (depends on 1) The apparatus according to claim 1 wherein said threshold generator comprises: a positive peak voltage detector connected to said partial integrator; a negative peak voltage detector connected to said partial integrator; and a voltage divider connected to an output of said positive peak voltage detector and an output of said negative peak voltage detector. ### Claim 10 (depends on 9) The apparatus according to claim 9 wherein said feedback path is connected to said positive peak voltage detector and to said negative peak voltage detector, said feedback loop thereby alternately causing an adjustment to a detected positive peak voltage and a detected negative peak voltage as a function of a state of said feedback path. ### Claim 11 (depends on 10) The apparatus according to claim 10 wherein said detected positive peak voltage is adjusted by decreasing its magnitude when said feedback path is in one of two states, and said detected negative peak voltage is adjusted by decreasing its magnitude when said feedback path is in another of said two states. ### Claim 12 A method for retrieving data information from a playback signal, said method comprising the steps of: differentiating said playback signal to thereby generate a differentiated signal; equalizing said differentiated signal to generate an equalized signal; partially integrating said equalized signal after said differentiating step; generating a threshold signal which tracks the DC component of said partially integrated signal; generating an output signal by comparing said partially integrated signal to said threshold signal; and adjusting said threshold signal in response to said output signal.