Patent US3701941A successfully refreshed from Google Patents.
US3701941A
Expired / Lapsed
US
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Magnetic anomaly detector with means for obtaining different test frequencies
Assignee: Branson Ultrasonics Corp
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Filing: 1971-09-28
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Granted: 1972-10-31
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Expires: 1991-09-28
Abstract
Abstract A magnetic detecting apparatus comprises a probe having two coils which are moved through a metallic workpiece (tubing) to detect anomalies. The coils are connected to an electronic circuit which includes two oscillators whose output frequencies are subtracted to provide a signal of suitable frequency to the probe coils. Additionally, phase shift means are provided to produce a balancing signal in order to analyze and display the anomaly responsive signal produced by the test coils with respect to phase and amplitude. Different test frequencies are obtained by changing the frequency of one of the oscillators.
Inventors
- 👤 Walter J Bantz
- 👤 Richard J Pittaro
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 12:57
CPC Classifications
G; G01; G01N; G01N27/00; G01N27/72; G01N27/82; G01N27/90; G01N27/9046
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
345 words
A magnetic detecting apparatus comprising: oscillator means for providing electrical signals at a first frequency f1 and at a second frequency f1 + Delta f; means coupled for receiving said signals provided by said oscillator means and for producing a first output signal which is the difference frequency Delta f between said frequencies and for producing also a second output signal corresponding to said difference Delta f which is phase shifted relative to said first output signal; a balancing means coupled for receiving said first and said second output signal and including phase shift means for providing a third output at the frequency Delta f which is phase shifted relative to said first and said second output signals responsive to the setting of said phase shift means, and said balancing means including means for providing another output signal serving as a balancing signal; a sensing probe adapted to be inductively coupled to a workpiece, said probe having coil means coupled for receiving at an input connection said third output signal and providing a fourth output signal whose frequency is said difference Delta f and whose phase and amplitude, when testing a workpiece, is indicative of anomalies of a workpiece sensed by said probe; difference means coupled to said probe for receiving said fourth output signal from said sensing probe and connected also for receiving said balancing signal from said balancing means for producing a fifth output signal at the frequency Delta f which is indicative of the difference of phase and amplitude between said signals received by said difference means; means coupled for receiving said output signal from said difference means and a signal at the frequency f1 + Delta f from said oscillator means and providing a signal at the frequency f1 having phase and amplitude information indicative of the anomalies, and phase dIscriminating heterodyne filter means coupled for receiving said output signal from said last mentioned means and for receiving also signals from said oscillator means for providing direct current output signal information which is indicative of the anomalies sensed by said probe.
Claim 2
Dependent Claim
345 words
A magnetic detecting apparatus comprising: oscillator means for providing electrical signals at a first frequency f1 and at a second frequency f1 + Delta f; means coupled for receiving said signals provided by said oscillator means and for producing a first output signal which is the difference frequency Delta f between said frequencies and for producing also a second output signal corresponding to said difference Delta f which is phase shifted relative to said first output signal; a balancing means coupled for receiving said first and said second output signal and including phase shift means for providing a third output at the frequency Delta f which is phase shifted relative to said first and said second output signals responsive to the setting of said phase shift means, and said balancing means including means for providing another output signal serving as a balancing signal; a sensing probe adapted to be inductively coupled to a workpiece, said probe having coil means coupled for receiving at an input connection said third output signal and providing a fourth output signal whose frequency is said difference Delta f and whose phase and amplitude, when testing a workpiece, is indicative of anomalies of a workpiece sensed by said probe; difference means coupled to said probe for receiving said fourth output signal from said sensing probe and connected also for receiving said balancing signal from said balancing means for producing a fifth output signal at the frequency Delta f which is indicative of the difference of phase and amplitude between said signals received by said difference means; means coupled for receiving said output signal from said difference means and a signal at the frequency f1 + Delta f from said oscillator means and providing a signal at the frequency f1 having phase and amplitude information indicative of the anomalies, and phase dIscriminating heterodyne filter means coupled for receiving said output signal from said last mentioned means and for receiving also signals from said oscillator means for providing direct current output signal information which is indicative of the anomalies sensed by said probe.
Claim 3
Dependent Claim
37 words
A magnetic detecting apparatus as set forth in claim 1, said balancing means including phase and amplitude adjusting means for balancing said fourth output signal provided by said difference means prior to testing a workpiece for anomalies.
Claim 4
Dependent Claim
91 words
A magnetic detecting apparatus as set forth in claim 1, said second output signal being phase shifted by substantially 90* electrical relative to said first output signal; said balancing means having means for causing said third output signal to be shifted by substantially 45* electrical; said balancing means also including adjustable phase and amplitude control means for causing said balancing signal to be variable in amplitude and phase from substantially 0* to 90* for balancing said fourth output signal provided by said difference means prior to testing a workpiece for anomalies.
Claim 5
Dependent Claim
20 words
A magnetic detecting apparatus as set forth in claim 1, said sensing probe including a pair of axially spaced coils.
Claim 6
Dependent Claim
26 words
A magnetic detecting apparatus as set forth in claim 1, said sensing probe including a pair of axially spaced coils coupled in series with one another.
Claim 7
Dependent Claim
22 words
A magnetic detecting apparatus as set forth in claim 5 and means for rendering one of said coils not responsive to anomalies.
Claim 8
Dependent Claim
53 words
A magnetic detecting apparatus as set forth in claim 1, said coil means comprising a pair of substantially equal coils, and impedance means disposed in series relationship with one of said coils for electrically unbalancing said one coil, and switch means for selectively connecting and disconnecting said impedance means from said one coil.
Claim 9
Dependent Claim
39 words
A magnetic detecting apparatus as set forth in claim 1, and phase shifting means coupled in circuit between said oscillator means and said phase discriminating heterodyne filter means for shifting said output signal information when displayed for visual observation.
Claim 10
Dependent Claim
26 words
A magnetic detecting apparatus as set forth in claim 8, said phase shifting means including control means for providing adjustable phase control for the displayed signal.
Claim 11
Dependent Claim
48 words
A magnetic detecting apparatus as set forth in claim 1, said oscillator means including a crystal controlled oscillator, a plurality of crystals of different frequency, and switching means coupled for selectively coupling one of said crystals in circuit to cause said oscillator means to provide a selected frequency.
Claim 12
Dependent Claim
25 words
A magnetic detecting apparatus as set forth in claim 1, said means for producing said first and second output signal including a frequency subtracting means.
Claim 13
Dependent Claim
23 words
A magnetic detecting apparatus as set forth in claim 1, and means coupled to said filter means for displaying said output signal information.
Claim 14
Dependent Claim
19 words
A magnetic detecting apparatus as set forth in claim 12, said means for displaying being a strip chart recorder.
Claim 15
Dependent Claim
19 words
A magnetic detecting apparatus as set forth in claim 12, said means for displaying including a cathode ray tube.
Claim 16
Dependent Claim
46 words
A magnetic detecting apparatus as set forth in claim 1, said phase discriminating heterodyne filter means including means for causing said output signal information to comprise two output signals having a 90* phase shift relation with respect to each other to provide amplitude and phase information.
Claim 17
Dependent Claim
228 words
A magnetic detecting apparatus comprising: a pair of oscillator means providing respective signals at a frequency f1 and a frequency f1 + Delta f; means coupled for receiving said signals and providing a first output signal which is the difference frequency Delta f between said respective signals; a sensing probe adapted to be inductively coupled to a workpiece, said probe including coil means for receiving aT an input connection a signal responsive to said first output signal and providing a second output signal indicative of anomalies of a workpiece sensed by said probe; phase and amplitude balancing means coupled in electrical circuit with said coil means; a difference means coupled to said coil means and balancing means for producing a third output signal which is responsive to the setting of said balancing means and said second output signal provided by said coil means; mixing means coupled for receiving said third output signal and for receiving a signal from said oscillator means to provide a fourth output signal having a frequency f1 and including anomaly responsive information; a heterodyne filter means coupled for receiving said fourth output signal and also a signal from said oscillator means for providing a fifth output signal which is indicative of the anomalies sensed by said probe, and means coupled to said filter means for indicating a value commensurate with said fifth output signal.
Claim 18
Dependent Claim
228 words
A magnetic detecting apparatus comprising: a pair of oscillator means providing respective signals at a frequency f1 and a frequency f1 + Delta f; means coupled for receiving said signals and providing a first output signal which is the difference frequency Delta f between said respective signals; a sensing probe adapted to be inductively coupled to a workpiece, said probe including coil means for receiving aT an input connection a signal responsive to said first output signal and providing a second output signal indicative of anomalies of a workpiece sensed by said probe; phase and amplitude balancing means coupled in electrical circuit with said coil means; a difference means coupled to said coil means and balancing means for producing a third output signal which is responsive to the setting of said balancing means and said second output signal provided by said coil means; mixing means coupled for receiving said third output signal and for receiving a signal from said oscillator means to provide a fourth output signal having a frequency f1 and including anomaly responsive information; a heterodyne filter means coupled for receiving said fourth output signal and also a signal from said oscillator means for providing a fifth output signal which is indicative of the anomalies sensed by said probe, and means coupled to said filter means for indicating a value commensurate with said fifth output signal.
Claim 19
Dependent Claim
23 words
A magnetic detecting apparatus as set forth in claim 16, said coil means and said balancing means comprising in combination a bridge circuit.
Claim 20
Dependent Claim
49 words
A magnetic detecting apparatus as set forth in claim 17, said coil means comprising two axially spaced annular coils, said balancing means comprising two resistors having variable sliding contacts, said coils and resistors forming respective arms of said bridge circuit, and said contacts being coupled to said difference means.
Claim 21
Dependent Claim
43 words
A magnetic detecting apparatus as set forth in claim 16, said heterodyne filter means including two channels, and a phase shift means coupled in circuit between said oscillator means and one of said channels to provide phase discrimination for said fifth output signal.
Claim 22
Dependent Claim
36 words
A magnetic detecting apparatus as set forth in claim 19, said phase shift means providing substantially 90* phase shift to cause two output signals which are phase discriminated by substantially 90* with respect to one another.
References Cited (Backward Citations)
US3050678A
Cited
US3478263A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-10-31 | 1976-05-01 | 1976-10-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-10-31 | 1980-05-01 | 1980-10-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-10-31 | 1984-05-01 | 1984-10-31 | $7700.00 | Window Closed / Lapsed |