US3825838A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Search tune detector circuit
Assignee: Philips North America LLC
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Filing: 1972-08-03
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Granted: 1974-07-23
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Expires: 1992-08-03
Abstract
Abstract An improved circuit for indicating the tuning of a heterodyne television receiver to an active station and for providing an output signal indicative thereof is disclosed. The circuit employs a tuned circuit resonant at an intermediate frequency of the receiver for sensing proper tuning but allows this resonant circuit to sense only during the concurrence of flyback and synchronizing signals. A Darlington pair senses resonance in the resonant circuit and provides a search tune stop signal when that resonance occurs. The Darlington pair also functions to cause inhibition of the receiver audio signal during search tuning and to prevent resonance in the tuned circuit at times other than during search tuning.
Inventors
- 👤 L Mayle
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 12:38
CPC Classifications
H; H03; H03J; H03J7/00; H03J7/02; H03J7/023; H03J7/18; H03J7/30; H03J7/305
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
167 words
In a search tune heterodyne television receiver, a circuit for detecting the tuning of the receiver to an active station and for providing an output signal indicative of the receiver being tuned to an active station comprising: tuned cIrcuit means resonant at an intermediate frequency of the receiver and coupled to a point in the receiver where an intermediate frequency appears when the receiver is properly tuned to an active station; search tuning means for causing a receiver tuner to search-tune for an active station; reactive means; means for selectively connecting said reactive means to said tuned circuit means to thereby selectively change the resonant frequency of the said tuned circuit means at all receiver operation periods other than at least a portion of the active search period of said search tuning means; and means responsive to resonance of said tuned circuit means for providing an output signal for disabling receiver search tuning of said search tuning means when the receiver is tuned to an active station.
Claim 2
Dependent Claim
167 words
In a search tune heterodyne television receiver, a circuit for detecting the tuning of the receiver to an active station and for providing an output signal indicative of the receiver being tuned to an active station comprising: tuned cIrcuit means resonant at an intermediate frequency of the receiver and coupled to a point in the receiver where an intermediate frequency appears when the receiver is properly tuned to an active station; search tuning means for causing a receiver tuner to search-tune for an active station; reactive means; means for selectively connecting said reactive means to said tuned circuit means to thereby selectively change the resonant frequency of the said tuned circuit means at all receiver operation periods other than at least a portion of the active search period of said search tuning means; and means responsive to resonance of said tuned circuit means for providing an output signal for disabling receiver search tuning of said search tuning means when the receiver is tuned to an active station.
Claim 3
Dependent Claim
68 words
The apparatus of claim 1 wherein said selectively connecting means comprises; means for sensing the synchronizing pulses and the presence of intermediate frequency signals and for changing the resonant frequency of said tuned circuit means on coincidence of said synchronizing pulses and presence of intermediate frequency to cause said tuned circuit means to be resonance at said coincidence and to be out of resonance at all other times.
Claim 4
Dependent Claim
98 words
The apparatus of claim 2 with diode means connecting said tuned circuit means and said reactive means; transistor means connecting said tuned circuit means and said search tune means to deactivate said search tuning means upon resonance of said tuned circuit means; said selective connecting means being connected to said diode means to cause said diode means to open upon the presence of synchronizing pulses to thereby disconnect said reactive means from said tuned circuit means during synchronizing pulses to cause said tuned circuit means to resonate and operate said transistor means to deactivate said search tuning means.
Claim 5
Dependent Claim
166 words
In a search tune heterodyne television receiver, a circuit for detecting the tuning of the receiver to an active station and for providing an output signal indicative of the receiver being tuned to an active station comprising: tuned circuit means resonant at an intermediate frequency of the receiver and coupled to a point in the receiver where an intermediate frequency appears when the receiver is properly tuned to an active station; search tuning means for causing a receiver tuner to search-tune for an active station; damping means; means for selectively connecting said damping means to said tuned circuit means to thereby selectively damp the resonant oscillations of the said tuned circuit means at all receiver operation periods other than at least a portion of the active search period of said search tuning means; and means responsive to resonance of said tuned circuit means for providing output signal for disabling receiver search tuning of said search tuning means when the receiver is tuned to an active station.
Claim 6
Dependent Claim
166 words
In a search tune heterodyne television receiver, a circuit for detecting the tuning of the receiver to an active station and for providing an output signal indicative of the receiver being tuned to an active station comprising: tuned circuit means resonant at an intermediate frequency of the receiver and coupled to a point in the receiver where an intermediate frequency appears when the receiver is properly tuned to an active station; search tuning means for causing a receiver tuner to search-tune for an active station; damping means; means for selectively connecting said damping means to said tuned circuit means to thereby selectively damp the resonant oscillations of the said tuned circuit means at all receiver operation periods other than at least a portion of the active search period of said search tuning means; and means responsive to resonance of said tuned circuit means for providing output signal for disabling receiver search tuning of said search tuning means when the receiver is tuned to an active station.
Claim 7
Dependent Claim
79 words
The apparatus of claim 4 with said damping means comprising switchable conductive means connected to said tuned circuit means, control means for switching said conductive means to a non-conductive state upon presence of a search condition of said search tuning means, second control means for switching said conductive means to a conductive state upon tuning of said television receiver to an active station to thereby load said tune circuit means and damp the oscillations in said tuned circuit means.
Claim 8
Dependent Claim
59 words
The apparatus of claim 5 with said selective connection means comprising means for detecting coincidence of the receiver flyback pulses, synchronization pulses, and presence of intermediate frequency carrier oscillations, to switch said conductive means to a non-conductive state thereby unloading said tuned circuit means to cause operative resonance of said tuned circuit means to deactivate said search tuning means.
Claim 9
Dependent Claim
48 words
The apparatus of claim 6 with said conductive means being switched to a conductive state upon operative resonance of Said tuned circuit means to stop said search tuning means and at the same time load said tuned circuit means to damp resonant oscillations to a substantially lower amplitude.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-07-22 | 1978-01-21 | 1978-07-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-07-22 | 1982-01-21 | 1982-07-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-07-22 | 1986-01-21 | 1986-07-23 | $7700.00 | Window Closed / Lapsed |