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Patent US4722010A successfully refreshed from Google Patents.
US4722010A
Expired / Lapsed
US
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Read circuit for floppy disk drive
Assignee: Toshiba Corp
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Filing: 1986-04-28
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Granted: 1988-01-26
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Expires: 2006-04-28
Abstract
Abstract In a read circuit for an FDD, a differentiator is constituted by a pair of current control transistors connected differentially, and a series circuit of a capacitor, an inductor, and first and second resistors connected between the transistors. A switch is connected across one of the resistors. When a track counter detects an inner track, it supplies an active signal to the switch. The switch is closed to short-circuit the resistor, thereby decreasing the damping value of the differentiator.
Inventors
- 👤 Hiroshi Suzuki
- 👤 Shouji Nakajima
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 22:40
CPC Classifications
G; G11; G11B; G11B20/00; G11B20/10; G11B20/10009; G11B5/00; G11B5/012; G11B5/016
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
190 words
A read circuit for a floppy disk drive, for receiving an analog signal read by a magnetic head from a disk on which data is written such that a recording density of inner tracks is higher than that of outer tracks, and which outputs pulse data, comprising: inner/outer track detecting means for detecting if the magnetic head has accessed an inner or outer track of the disk; a low-pass filter for eliminating a high-frequency component of the analog signal; a differentiator having a pair of current control elements connected differentially, and a series circuit of a capacitor, an inductor and first and second resistors connected in series between said pair of current control elements, said differentiator being arranged to differentiate the analog signal from said low-pass filter; resistor short-circuiting means for short-circuiting both terminals of one of said first and second resistors so as to decrease a damping value of said differentiator when a signal supplied from said inner/outer track detecting means is an active signal representing the inner track; and a zero-cross comparator for generating a pulse synchronized with the zero-crossing of a differentiated analog signal from said differentiator.
Claim 2
Dependent Claim
190 words
A read circuit for a floppy disk drive, for receiving an analog signal read by a magnetic head from a disk on which data is written such that a recording density of inner tracks is higher than that of outer tracks, and which outputs pulse data, comprising: inner/outer track detecting means for detecting if the magnetic head has accessed an inner or outer track of the disk; a low-pass filter for eliminating a high-frequency component of the analog signal; a differentiator having a pair of current control elements connected differentially, and a series circuit of a capacitor, an inductor and first and second resistors connected in series between said pair of current control elements, said differentiator being arranged to differentiate the analog signal from said low-pass filter; resistor short-circuiting means for short-circuiting both terminals of one of said first and second resistors so as to decrease a damping value of said differentiator when a signal supplied from said inner/outer track detecting means is an active signal representing the inner track; and a zero-cross comparator for generating a pulse synchronized with the zero-crossing of a differentiated analog signal from said differentiator.
Claim 3
Dependent Claim
157 words
A read circuit for a floppy disk drive, which causes a magnetic head to read data from magnetic recording media recorded in one of a plurality of different recording modes corresponding to different recording densities, differentiates a read signal from the magnetic head, and outputs read data pulses in accordance with a differentiated signal, comprising: a plurality of differential filter means having filter characteristics corresponding to frequency bands of the read signal which are determined by the recording mode of the magnetic recording media, respectively; means for selecting an optimal one of said plurality of differential filter means which corresponds to a given frequency band of the read signal in response to an external selection signal, the given frequency band being determined by a corresponding one of the recording modes of the magnetic recording media; and means for outputting as the differential signal a signal generated by said differential filter means and selected by said selecting means.
Claim 4
Dependent Claim
157 words
A read circuit for a floppy disk drive, which causes a magnetic head to read data from magnetic recording media recorded in one of a plurality of different recording modes corresponding to different recording densities, differentiates a read signal from the magnetic head, and outputs read data pulses in accordance with a differentiated signal, comprising: a plurality of differential filter means having filter characteristics corresponding to frequency bands of the read signal which are determined by the recording mode of the magnetic recording media, respectively; means for selecting an optimal one of said plurality of differential filter means which corresponds to a given frequency band of the read signal in response to an external selection signal, the given frequency band being determined by a corresponding one of the recording modes of the magnetic recording media; and means for outputting as the differential signal a signal generated by said differential filter means and selected by said selecting means.
Claim 5
Dependent Claim
26 words
A circuit according to claim 2, wherein each of said plurality of filter means comprises a series circuit of a capacitor, an inductor, and a resistor.
Claim 6
Dependent Claim
29 words
A circuit according to claim 2, wherein each of said plurality of differential filter means comprises a common capacitor and a series circuit of an inductor and a resistor.
References Cited (Backward Citations)
US4244008A
Cited
US4564869A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-01-25 | 1991-07-27 | 1992-01-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-01-25 | 1995-07-27 | 1996-01-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-01-25 | 1999-07-27 | 2000-01-26 | $7700.00 | Window Closed / Lapsed |