# US 5,351,222 A · Disk storage apparatus including a single power supply hysteresis comparator having a symmetrical characteristic > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,351,222 A - Document ID: US5351222A - Status: Granted - Kind: A - Application number: 07/957,521 - Filed: 1992-10-06 - Granted: 1994-09-27 - Earliest claimed: 1991-10-08 - Assignees: Fujitsu Limited - Inventors: Toru Ikeda; Shigenori Yanagi - Web page: https://patentgrep.com/patent/US5351222A ## CPC - G11B 7/08541: {involving track counting to determine position} - 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 A rectangular wave generator includes a comparator having a first input terminal receiving an input signal, a second input terminal, and an output terminal. The comparator slices the input signal at a hysteresis voltage so that a rectangular wave is output via the output terminal. The generator also includes a differentiating circuit connected between the output terminal and the second input terminal. The differentiating circuit functions as a feedback circuit. In lieu of the differentiating circuit, it is possible to use a feedback circuit connected between the output terminal and the second input terminal, the feedback circuit comprising a control unit for changing a feedback quantity of the differentiating circuit in accordance with variations in a frequency of the input signal. ## Claims ### Claim 1 A disk storage apparatus comprising: an optical scanning system movable with respect to a disk-shaped medium, said optical scanning system generating an electric read signal obtained by optically scanning the disk-shaped medium; reproducing means, coupled to said optical scanning system, for reproducing information from the electric read signal; seek control means, coupled to said optical scanning system, for controlling a seek speed so that the optical scanning system can move to a target track on the disk-shaped medium; position error signal generating means for generating a position error signal from said electric signal, said position error signal indicating an error in a position of tracking by means of said optical scanning system; and a rectangular wave generator, said rectangular wave generator including: a comparator having a first input terminal receiving said position error signal, a second input terminal, and an output terminal, the comparator slicing the position error signal at a hysteresis voltage so that a rectangular wave corresponding to said seek control signal is output via the output terminal; and a feedback circuit connected between the output terminal and the second input terminal, said feedback circuit including means for changing a feedback quantity in accordance with variations of the seek speed. ### Claim 2 (depends on 1) A disk storage apparatus as claimed in claim 1, wherein said feedback circuit has a time constant which attenuates the position error signal in an attenuation time longer than a cycle of the position error signal. ### Claim 3 (depends on 1) A disk storage apparatus as claimed in claim 1, wherein said feedback circuit has a feedback quantity less than an amplitude of the position error signal. ### Claim 4 (depends on 1) A disk storage apparatus as claimed in claim 1, further comprising feedback control means for changing a feedback quantity of said feedback circuit in accordance with variations in a frequency of the position error signal. ### Claim 5 (depends on 4) A disk storage apparatus as claimed in claim 4, wherein said feedback control mans comprises means for changing the feedback quantity so that a hysteresis width of the hysteresis voltage decreases as the frequency of the position error signal becomes higher. ### Claim 6 (depends on 1) A disk storage apparatus as claimed in claim 1, wherein said feedback circuit comprises a first resistor and a capacitor connected in series. ### Claim 7 (depends on 6) A disk storage apparatus as claimed in claim 6, wherein: said feedback circuit further comprises a series circuit comprising a second resistor and a switch; and said series circuit being connected to said first resistor in parallel. ### Claim 8 (depends on 7) A disk storage apparatus as claimed in claim 7, further comprising feedback control means, coupled to said series circuit, for controlling said switch in accordance with a frequency of said position error signal so that a hysteresis width of the hysteresis voltage decreases as the frequency of the position error signal becomes higher. ### Claim 9 A disk storage apparatus comprising an optical scanning system movable with respect to a disk-shaped medium, said optical scanning system generating an electric read signal obtained by optically scanning the disk-shaped medium; reproducing means, coupled to said optical scanning system, for reproducing information from the electric read signal; and seek control means, coupled to said optical scanning system, for generating a seek control signal from said electric read signal, said seek control means comprising: position error signal generating means for generating a position error signal from said electric read signal, said position error signal indicating an error in a position of tracking by means of said optical scanning system; and a rectangular wave generator, said rectangular wave generator comprising: a comparator having a first input terminal receiving said position error signal, a second input terminal, and an output terminal, the comparator sliding the position error signal at a hysteresis voltage so that a rectangular wave corresponding to said seek control signal is output via the output terminal; and a feedback circuit connected between the output terminal and the second input terminal, said feedback circuit comprising feedback control means for changing a feedback quantity of said feedback circuit in accordance with variations in a frequency of the position error signal. ### Claim 10 (depends on 9) A disk storage apparatus as claimed in claim 9, wherein said feedback circuit further comprises: a first resistor connected to the output terminal of said comparator and to the second input terminal; and a series circuit comprising a second resistor and a switch, said series circuit being connected to said first resistor in parallel, wherein said control means comprises means or controlling the switch so that a hysteresis width of the hysteresis voltage decreases as the frequency of the position error signal becomes higher. ### Claim 11 (depends on 10) A disk storage apparatus as claimed in claim 10, wherein said feedback circuit further comprises a capacitor inserted between said first resistor and said second input terminal of said comparator.