US5087884A
Expired / Lapsed
US
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Open head detection circuit and method
Assignee: Vermont Technical College
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Filing: 1990-06-28
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Granted: 1992-02-11
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Expires: 2010-06-28
Abstract
Abstract An open head detection circuit for detecting an open-circuit condition in a magnetic head connected to head contacts. The detector circuit includes a threshold source which generates a threshold voltage that is between a head contact voltage representative of a connected head and a head contact voltage representative of an open head. A comparator, coupled to receive head voltage signals from the head contacts and coupled to the threshold source, compares the head voltage signals to the threshold voltage and generates comparator signals representative of the comparison. Sampling circuitry, coupled to the comparator and coupled to receive write data signals, samples the comparator signals after detection of the write data signals and before the write data signals affect the comparator signals.
Inventors
- 👤 Craig M. Brannon
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 15:34
CPC Classifications
G; G01; G01R; G01R31/00; G01R31/50; G01R31/54; G01R31/52
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
146 words
An open head detector circuit for detecting an open-circuit condition in a magnetic head having head contacts electrically coupled to write data circuitry responsive to write data signals for controlling current flow through the magnetic head, the detector circuit comprising: a threshold source for generating a threshold voltage that is between a head contact voltage representative of a connected head and a head contact voltage representative of an open head; a comparator coupled to receive head voltage signals from the head contacts and coupled to the threshold source for comparing the head voltage signals to the threshold voltage and for generating comparator signals representative of the comparison; and sampling circuitry coupled to the comparator and configured for coupling to receive the write data signals for sampling the comparator signals in response to the write data signals and before the write data signals affect the comparator signals.
Claim 2
Dependent Claim
146 words
An open head detector circuit for detecting an open-circuit condition in a magnetic head having head contacts electrically coupled to write data circuitry responsive to write data signals for controlling current flow through the magnetic head, the detector circuit comprising: a threshold source for generating a threshold voltage that is between a head contact voltage representative of a connected head and a head contact voltage representative of an open head; a comparator coupled to receive head voltage signals from the head contacts and coupled to the threshold source for comparing the head voltage signals to the threshold voltage and for generating comparator signals representative of the comparison; and sampling circuitry coupled to the comparator and configured for coupling to receive the write data signals for sampling the comparator signals in response to the write data signals and before the write data signals affect the comparator signals.
Claim 3
Dependent Claim
93 words
The open head detector circuit of claim 1 wherein the magnetic head includes first and second head contacts and wherein the open head detector circuit further comprises a differential amplifier connected between the first and second head contacts and the comparator, the differential amplifier having a first input terminal electrically connected to the first head contact, a second input terminal electrically connected to the second head contact and an output terminal connected to the comparator for producing amplified differential head voltage signals representative of differential voltages across the first and second head contacts.
Claim 4
Dependent Claim
17 words
The open head detector circuit of claim 2 wherein the differential amplifier has a gain of 1.
Claim 5
Dependent Claim
42 words
The open head detector circuit of claim 1 wherein the comparator comprises a first input terminal electrically connected to receive the head voltage signals, a second input terminal electrically connected to the threshold source, and an output terminal providing the comparator signals.
Claim 6
Dependent Claim
16 words
The open head detector circuit of claim 1 wherein the comparator signals are digital comparator signals.
Claim 7
Dependent Claim
60 words
The open head detector circuit of claim 5 wherein the sampling circuitry comprises a D-type flip-flop having a data input terminal electrically connected to receive the digital comparator signals from the comparator, a clock input terminal electrically connected to receive the write data signals, and an output terminal providing open head fault signals based upon the sampled digital comparator signals.
Claim 8
Dependent Claim
58 words
The open head detector circuit of claim 6 and further comprising an OR gate that is coupled to the output terminal of the D-type flip-flop and is coupled to receive other write fault signals for performing a logical OR function between the open head fault signals and the other write fault signals to generate write unsafe output signals.
Claim 9
Independent Claim
116 words
A method of detecting an open head condition in a magnetic head comprising the steps of: sensing voltages at magnetic head contacts; comparing the voltages at the magnetic head contacts to a reference voltage that is between a head contact voltage representative of a connected head and a head contact voltage representative of an open head; providing comparator signals representative of the comparison; receiving a write data signal; sampling the comparator signals upon detection of the write data signal, before the write data signal affects the comparator signals; providing open head fault signals as a function of the sampled comparator signals; and reversing current direction in the magnetic head in response to the write data signal.
Claim 10
Independent Claim
116 words
A method of detecting an open head condition in a magnetic head comprising the steps of: sensing voltages at magnetic head contacts; comparing the voltages at the magnetic head contacts to a reference voltage that is between a head contact voltage representative of a connected head and a head contact voltage representative of an open head; providing comparator signals representative of the comparison; receiving a write data signal; sampling the comparator signals upon detection of the write data signal, before the write data signal affects the comparator signals; providing open head fault signals as a function of the sampled comparator signals; and reversing current direction in the magnetic head in response to the write data signal.
Claim 11
Dependent Claim
45 words
The method of claim 8 wherein the step of sensing voltages includes the steps of: monitoring differential voltages across the magnetic head contacts with first and second input terminals of a differential amplifier; and producing amplified differential head voltage signals representative of the differential voltages.
Claim 12
Dependent Claim
35 words
The method of claim 9 wherein the step of comparing voltages at the magnetic head contacts to a reference voltage includes the step of comparing the amplified differential head voltage signals to the reference voltage.
Claim 13
Dependent Claim
28 words
The method of claim 8 wherein the step of providing comparator signals representative of the comparison includes the step of providing digital comparator signals representative of the comparison.
Claim 14
Dependent Claim
36 words
The method of claim 11 wherein the step of providing digital comparator signals includes the step of providing digital comparator signals indicative of whether the voltages at the head contacts are greater than the reference voltage.
Claim 15
Dependent Claim
22 words
The method of claim 11 wherein the step of sampling the comparator signals includes the step of sampling the digital comparator signals.
Claim 16
Dependent Claim
59 words
The method of claim 13 wherein the step of sampling the digital comparator signals includes the steps of: applying the digital comparator signals to a data input terminal of a D-type flip-flop; applying the write data signal to a clock input terminal of the D-type flip-flop; and latching the digital comparator signals upon detection of the write data signal.
Claim 17
Dependent Claim
33 words
The method of claim 14 wherein the step of latching the digital comparator signals includes the step of latching the digital comparator signals upon detection of an edge of a digital data pulse.
Claim 18
Dependent Claim
30 words
The method of claim 14 wherein the step of providing open head fault signals includes the step of providing open head fault signals representative of the latched digital comparator signals.
Claim 19
Dependent Claim
45 words
The method of claim 15 and further comprising the steps of: Receiving other write fault signals from other write data circuitry; and performing a logical OR function on the open head fault signals with the other write data fault signals to produce write unsafe signals.
Claim 20
Dependent Claim
43 words
The method of claim 13 wherein the step of providing an open head fault signal includes the step of providing an open head fault signal when the sampled comparator signals indicate the voltages at the head contacts are greater than the reference voltage.
Claim 21
Dependent Claim
27 words
The method of claim 13 wherein the step of sensing voltages at magnetic head contacts includes the step of sensing differential voltages across the magnetic head contacts.
Claim 22
Dependent Claim
22 words
The method of claim 8 wherein the step of receiving a write data signal includes the step of receiving a digital pulse.
Claim 23
Dependent Claim
49 words
The method of claim 19 wherein the step of sampling the comparator signals includes the step of sampling the comparator signals before changes in the voltages at the magnetic head contacts, caused by the step of reversing current direction in the magnetic head, propagate to affect the comparator signals.
References Cited (Backward Citations)
US3681682A
Cited
US4323844A
Cited
US4203137A
Cited
US4656420A
Cited
US4754222A
Cited
US4764729A
Cited
US4866376A
Cited
US4862078A
Cited
US4746869A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1995-02-10 | 1995-08-12 | 1996-02-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-02-10 | 1999-08-12 | 2000-02-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-02-10 | 2003-08-12 | 2004-02-11 | $7700.00 | Window Closed / Lapsed |