US3618119A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Compensation in a magentic write circuit
Assignee: Storage Technology Corp
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Filing: 1970-03-13
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Granted: 1971-11-02
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Expires: 1990-03-13
Abstract
Abstract In a magnetic tape recording system, the write driver circuit has write compensation which drives the write coil with current which is initially high and which has an exponentially decaying waveform from the high current level to a lower current level. The write compensation is used with phase-encoded write current signals which have short duration transitions and longer duration transitions. The write compensation circuit includes a resistance-capacitance network having a time constant such that the exponential decay from the high current level to the lower current level is not completed during the short duration transitions in the write current signal so that the current through the write coil is initially higher after a longer transition than after a short transition.
Inventors
- 👤 Juan A Rodriguez
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 13:27
CPC Classifications
G; G11; G11B; G11B20/00; G11B20/10; G11B20/10009; G11B20/10046; G11B20/10194; G11B5/00; G11B5/02; H; H03; H03K; H03K17/00; H03K17/16; G11B2005/0002; G11B2005/0005; G11B2005/001
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
133 words
In a system for recording on a magnetic medium including a write coil, means for driving said medium past said write coil, and means for generating a phase-encoded write current signal having traNsitions between a value of positive current and a value of negative current, a write driver circuit comprising: at least one output transistor, the collector of said transistor being connected to said write coil, means for applying said write current signal to the base of said transistor, and a capacitor means connected in the emitter circuit of said transistor for driving said write coil with current which is initially high and which has an exponentially decaying waveform from said high current level to a lower current level upon transition of said write current signal between said positive and negative current levels.
Claim 2
Dependent Claim
133 words
In a system for recording on a magnetic medium including a write coil, means for driving said medium past said write coil, and means for generating a phase-encoded write current signal having traNsitions between a value of positive current and a value of negative current, a write driver circuit comprising: at least one output transistor, the collector of said transistor being connected to said write coil, means for applying said write current signal to the base of said transistor, and a capacitor means connected in the emitter circuit of said transistor for driving said write coil with current which is initially high and which has an exponentially decaying waveform from said high current level to a lower current level upon transition of said write current signal between said positive and negative current levels.
Claim 3
Dependent Claim
81 words
The write driver circuit recited in claim 1 wherein said write current signal has short duration transitions and longer duration transitions, further comprising: resistors in circuit with said capacitor, the circuit having a time constant such that the exponential decay from said high current level to the lower current level is not completed during said shorter duration transitions in said write current signal, the current through said write coil being initially higher after a longer transition than after a short transition.
Claim 4
Dependent Claim
67 words
The system recited in claim 1 wherein a plurality of write driver circuits are connected to a single write bus and wherein each write driver circuit further comprises an input emitter-follower transistor which minimizes loading of the write bus, said emitter-follower transistor being back biased when power is removed from said write driver circuit so that fluctuation in the circuits are not impressed on said write bus.
Claim 5
Dependent Claim
35 words
The system recited in claim 1 comprising a pair of output transistors, said write coil being connected between the collectors of said output transistors, reference potential being connected to a tap of said write coil.
Claim 6
Dependent Claim
39 words
The system recited in claim 4 further comprising: a current switch including two transistors which are switched in conductivity by the transition in said write current signal, said current switch being connected to the bases of said output transistors.
Claim 7
Dependent Claim
41 words
The system recited in claim 5 wherein said write current signal is connected to the base of one transistor in said current switch and wherein a degaussing signal is selectively applied to the base of the other transistor in said switch.
Claim 8
Dependent Claim
56 words
The system recited in claim 4 wherein the emitter current for said output transistors is supplied through an emitter-follower, a write status signal being applied to the base of said emitter-follower so that no current is applied to said write coil when said write status signal indicates that said driver circuit is not the write status.
Claim 9
Dependent Claim
31 words
The system recited in claim 4 further comprising a resistance-capacitance network in the collector circuit of each output transistor to dissipate the power of the inductive kick of said write coil.
References Cited (Backward Citations)
US3503059A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-11-01 | 1975-05-03 | 1975-11-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-11-01 | 1979-05-03 | 1979-11-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-11-01 | 1983-05-03 | 1983-11-02 | $7700.00 | Window Closed / Lapsed |