EP0595350A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Reproducing circuit for a magnetic head
Assignee: Sony Corp
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Filing: 1993-10-29
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Granted: —
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Expires: 2013-10-29
Abstract
Abstract A recording/reproducing apparatus for a magneto-resistive (MR) head (13) having a playback amplifier (4), including a capacitor (26) for a dc feedback low-pass filter for dc feedback to an initial-stage transistor, and a differential amplifier (gm amplifier (24)), and switching means (36,37) for the gm amplifier and for the initial-stage amplifier operable at the time of recording/playback switching. The timing of the switching means is deviated for shortening the switching time interval. To this end, an output of the initial-stage transistor of a playback amplifier for a MR head is compared to reference voltage Vref by a gm amplifier and the low-pass filter is constituted by transconductance gm of the gm amplifier and the capacitance of the capacitor, with the dc output of the gm amplifier being fed back to the base of the initial-stage amplifier. The delay in switching time by the charging of the capacitor caused by the difference in the rise time of the initial-stage transistor and the gm amplifier is deviated by the control signal from a control circuit to control the initial-stage transistor and the gm amplifier.
Inventors
- 👤 Sasaki Yasuo
- 👤 Fukuyama Munekatsu
- 👤 Kurihara Kazuo
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-04 15:51
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/48; G11B5/54; G11B15/00; G11B15/02; G11B15/12; G11B15/125; G11B19/00; G11B19/02; G11B5/02; G11B5/09; H; H03; H03F; H03F3/00; H03F3/72; G11B2005/0002; G11B2005/0005; G11B2005/001; G11B2005/0013; G11B2005/0016; G11B2005/0018
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
103 words
A recording/reproducing apparatus for a magneto-resistive head comprising an initial-stage amplifying means for amplifying an output signal from a magneto-resistive head, a voltage-to-current converting amplifier for amplifying a differential signal between an output signal of said initial-stage amplifying means and a reference voltage, feedback means for feeding back an output signal of said voltage-to-current converting amplifying means to an input side of said an initial-stage amplifying means, and controlling means for causing a first on-off timing of said differential amplifier, and a second on-off timing of said an initial-stage amplifying means, said first and second timings being different with respect to each other.
Claim 2
Dependent Claim
79 words
A recording/reproducing apparatus for a magneto-resistive head comprising an initial-stage amplifying means for amplifying an output signal from a magneto-resistive head, a variable gain type voltage-to-current converting amplifier for amplifying a differential signal between an output signal of said initial-stage amplifying means and a reference voltage, and feedback means for feeding back a dc component of an output signal from said voltage-to-current converting amplifying means to an input side of said an initial-stage amplifying means via a low-pass filter.
Claim 3
Dependent Claim
89 words
A recording/reproducing apparatus for a magneto-resistive head comprising a dc blocking capacitor for providing an unbalanced output signal of said magneto-resistive head, an initial-stage amplifying means for amplifying an output signal from a magneto-resistive head, a variable gain type voltage-to-current converting amplifier for amplifying a differential signal between an output signal of said initial-stage amplifying means and a reference voltage, and feedback means for feeding back a dc component of an output signal from said voltage-to-current converting amplifying means to an input side of said an initial-stage amplifying means.
Claim 4
Dependent Claim
53 words
The recording/reproducing apparatus for the magneto-resistive head as claimed in claim 1 wherein said controlling means causes said differential amplifier to be turned off when switching said magneto-resistive head from the playback state to the recording state, said controlling means causing said initial-stage amplifier to be subsequently turned off after a predetermined time.
Claim 5
Dependent Claim
53 words
The recording/reproducing apparatus for the magneto-resistive head as claimed in claim 1 wherein said controlling means causes said initial-stage amplifier to be turned on when switching said magneto-resistive head from the playback state to the recording state, said controlling means causing said differential amplifier to be subsequently turned on after a predetermined time.
Claim 6
Dependent Claim
20 words
The recording/reproducing apparatus for the magneto-resistive head as claimed in claim 1 wherein said initial-stage amplifier is a base-grounded amplifier.
Claim 7
Dependent Claim
20 words
The recording/reproducing apparatus for the magneto-resistive head as claimed in claim 1 wherein said initial-stage amplifier is an emitter-grounded amplifier.
Claim 8
Dependent Claim
30 words
The recording/reproducing apparatus for the magneto-resistive head as claimed in claim 2 wherein said variable gain type voltage-to-current converting amplifying means include two differential amplifiers for outputting output signals alternately.
Claim 9
Dependent Claim
20 words
The recording/reproducing apparatus for the magneto-resistive head as claimed in claim 2 wherein said initial-stage amplifier is a base-grounded amplifier.
Claim 10
Dependent Claim
20 words
The recording/reproducing apparatus for the magneto-resistive head as claimed in claim 2 wherein said initial-stage amplifier is an emitter-grounded amplifier.
Claim 11
Dependent Claim
101 words
A playback circuit for a magnetic head comprising an initial-stage amplifying means for amplifying an output signal from a magneto-resistive head, a voltage-to-current converting amplifying means for amplifying a differential signal between an output signal of said initial-stage amplifying means and a reference voltage, a constant current source connected to an output terminal of said voltage-to-current converting amplifying means,current amplifying means for amplifying an output signal of said voltage-to-current converting amplifying means,a capacitor connected to said current amplifying means, and feedback means for feeding back an output of said current amplifying means to an input side of said initial-stage amplifying means.
Claim 12
Dependent Claim
21 words
The playback circuit for the magnetic head as claimed in claim 11 wherein said initial-stage amplifying means is a base-grounded amplifier.
Claim 13
Dependent Claim
21 words
The playback circuit for the magnetic head as claimed in claim 11 wherein said initial-stage amplifying means is an emitter-grounded amplifier.
Claim 14
Dependent Claim
85 words
A playback circuit for a magnetic head comprising an initial-stage amplifying means for amplifying an output signal from a magneto-resistive head, voltage-to-current converting amplifying means supplied with an output signal of said an initial-stage amplifying means, said voltage-to-current converting amplifying means having input/output characteristics represented by an exponential function, a capacitor connected to an output terminal of said voltage-to-current converting amplifying means, and feedback means for feeding back an output of said voltage-to-current converting amplifying means to an input side of said initial-stage amplifying means.
Claim 15
Dependent Claim
54 words
The playback circuit for the magnetic head as claimed in claim 14 wherein said voltage-to-current converting amplifying means comprises a voltage-to-current converter for converting an input current to an electric current and a current amplifier for amplifying the current converted by said voltage-to-current converter by exponential input/output characteristics and outputting the resulting amplified current.
Claim 16
Dependent Claim
21 words
The playback circuit for the magnetic head as claimed in claim 15 wherein said current amplifier is formed by plural stages.
Claim 17
Dependent Claim
21 words
The playback circuit for the magnetic head as claimed in claim 14 wherein said initial-stage amplifying means is a base-grounded amplifier.
Claim 18
Dependent Claim
21 words
The playback circuit for the magnetic head as claimed in claim 14 wherein said initial-stage amplifying means is an emitter-grounded amplifier.
References Cited (Backward Citations)
No citation records indexed.
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