Patent US4999732A successfully refreshed from Google Patents.
US4999732A
Expired / Lapsed
US
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Degaussing circuit for CRT
Assignee: Murata Manufacturing Co Ltd
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Filing: 1988-11-10
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Granted: 1991-03-12
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Expires: 2008-11-10
Abstract
Abstract A degaussing circuit for degaussing a cathode ray tube has a degaussing coil mounted on the back of the catode ray tube and a positive temperature coefficient thermistor connected in series with the degaussing coil. The resonance frequency determined by the degaussing coil and the positive temperature coefficient thermistor is set to be below about 14 kHz or above about 17 kHz.
Inventors
- 👤 Masahito Mihara
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 05:03
CPC Classifications
H; H04; H04N; H04N9/00; H04N9/12; H04N9/16; H04N9/29
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
112 words
A degaussing circuit for degaussing a cathode ray tube having a degaussing coil mounted on a back of said cathode ray tube and a positive temperature coefficient thermistor connected in series with said degaussing coil; said series connection of said degaussing coil and PTC thermistor being connected across a low-frequency AC line supply so that a degaussing current having said low frequency of said AC line supply passes through said degaussing coil; wherein the degaussing coil has an inductance and the thermistor has a capacitance; and wherein a resonance frequency determined by the inductance of said degaussing coil and the capacitance of said positive temperature coefficient thermistor is below substantially 14 kHz.
Claim 2
Dependent Claim
112 words
A degaussing circuit for degaussing a cathode ray tube having a degaussing coil mounted on a back of said cathode ray tube and a positive temperature coefficient thermistor connected in series with said degaussing coil; said series connection of said degaussing coil and PTC thermistor being connected across a low-frequency AC line supply so that a degaussing current having said low frequency of said AC line supply passes through said degaussing coil; wherein the degaussing coil has an inductance and the thermistor has a capacitance; and wherein a resonance frequency determined by the inductance of said degaussing coil and the capacitance of said positive temperature coefficient thermistor is below substantially 14 kHz.
Claim 3
Dependent Claim
22 words
A degaussing circuit as claimed in claim 1, wherein said positive temperature coefficient thermistor has a capacitance of above about 10 nF.
Claim 4
Dependent Claim
19 words
A degaussing circuit as claimed in claim 2, wherein said degaussing coil has an inductance of about 10-20 mH.
Claim 5
Dependent Claim
67 words
A degaussing circuit as claimed in claim 1, wherein said degaussing circuit includes a second positive temperature coefficient thermistor connected across the above-mentioned series connection of said degaussing coil and thermistor; wherein said second thermistor has a second capacitance; and wherein a resonance frequency determined by the inductance of said degaussing coil and the capacitance of both said positive temperature coefficient thermistors is below substantially 14 kHz.
Claim 6
Dependent Claim
75 words
A degaussing circuit for degaussing a cathode ray tube having a degaussing coil mounted on a back of said cathode ray tube and a positive temperature coefficient thermistor connected in series with said degaussing coil; wherein the degaussing coil has an inductance and the thermistor has a capacitance; and wherein a resonance frequency determined by the inductance of said degaussing coil and the capacitance of said positive temperature coefficient thermistor is above substantially 17 kHz.
Claim 7
Dependent Claim
75 words
A degaussing circuit for degaussing a cathode ray tube having a degaussing coil mounted on a back of said cathode ray tube and a positive temperature coefficient thermistor connected in series with said degaussing coil; wherein the degaussing coil has an inductance and the thermistor has a capacitance; and wherein a resonance frequency determined by the inductance of said degaussing coil and the capacitance of said positive temperature coefficient thermistor is above substantially 17 kHz.
Claim 8
Dependent Claim
22 words
A degaussing circuit as claimed in claim 5, wherein said positive temperature coefficient thermistor has a capacitance of below about 4.5 nF.
Claim 9
Dependent Claim
19 words
A degaussing circuit as claimed in claim 6, wherein said degaussing coil has an inductance of about 10-20 mH.
Claim 10
Dependent Claim
67 words
A degaussing circuit as claimed in claim 5, wherein said degaussing circuit includes a second positive temperature coefficient thermistor connected across the above-mentioned series connection of said degaussing coil and thermistor; wherein said second thermistor has a second capacitance; and wherein a resonance frequency determined by the inductance of said degaussing coil and the capacitance of both said positive temperature coefficient thermistors is above substantially 17 kHz.
Claim 11
Dependent Claim
108 words
In a video display device including a cathode ray tube with a deflection yoke to which a deflection signal is supplied, a degaussing circuit for degaussing the cathode ray tube, said circuit including a degaussing coil mounted on a back of said cathode ray tube and a positive temperature coefficient thermistor connected in series with said degaussing coil; wherein the degaussing coil has an inductance and the thermistor has a capacitance; and wherein a resonance frequency determined by the inductance of said degaussing coil and the capacitance of said positive temperature coefficient thermistor is substantially offset from a frequency of the deflection signal supplied to the deflection yoke.
Claim 12
Dependent Claim
108 words
In a video display device including a cathode ray tube with a deflection yoke to which a deflection signal is supplied, a degaussing circuit for degaussing the cathode ray tube, said circuit including a degaussing coil mounted on a back of said cathode ray tube and a positive temperature coefficient thermistor connected in series with said degaussing coil; wherein the degaussing coil has an inductance and the thermistor has a capacitance; and wherein a resonance frequency determined by the inductance of said degaussing coil and the capacitance of said positive temperature coefficient thermistor is substantially offset from a frequency of the deflection signal supplied to the deflection yoke.
Claim 13
Dependent Claim
25 words
A degaussing circuit as claimed in claim 9, wherein said deflection frequency is substantially 15.75 kHz and said resonance frequency is below substantially 14 kHz.
Claim 14
Dependent Claim
25 words
A degaussing circuit as claimed in claim 9, wherein said deflection frequency is substantially 15.75 kHz and said resonance frequency is above substantnally 17 kHz.
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| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1994-03-11 | 1994-09-10 | 1995-03-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-03-11 | 1998-09-10 | 1999-03-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-03-11 | 2002-09-10 | 2003-03-12 | $7700.00 | Window Closed / Lapsed |