Patent JPH0210904A successfully refreshed from Google Patents.
US3852523A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Circuit for color television receivers
Assignee: RCA Licensing Corp
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Filing: 1973-04-09
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Granted: 1974-12-03
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Expires: 1993-04-09
Abstract
Abstract A circuit is disclosed which provides high attentuation to undesired 4.5 MHz. signals which appear in the output of a video detector. A trap circuit causes no attenuation of the chrominance signals which occur at slightly lower frequencies than 4.5 MHz. The trap is located after the video detector at a location following an emitter follower stage that processes signals generated by the video detector. The desired passband response is obtained by selection of impedance values for the load supplied by the trap circuit.
Inventors
- 👤 J Humphrey
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 15:28
CPC Classifications
H; H04; H04N; H04N9/00; H04N9/64; H04N9/646
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
153 words
In a color television receiver having a video detector circuit for producing a demodulated signal by demodulating an intermediate frequency signal applied to said detector, said intermediate frequency signal comprising a relatively wideband video signal and an audio signal and said demodulated signal containing a luminance signal, a chrominance signal and a difference signal having a frequency which is the difference between the intermediate frequency of said video signal and the intermediate frequency of said audio signal, an improved video signal circuit comprising: an emitter follower circuit connected to receive said demodulated signals; and a trap circuit for trapping said difference signal at the emitter of said emitter follower circuit wherein the output of said trap circuit is connected to a load, said load, as seen by the output of said tRap, being adjustable to emphasize a relatively narrow band of preselected video signal frequencies less than the frequency of said difference signal.
Claim 2
Dependent Claim
153 words
In a color television receiver having a video detector circuit for producing a demodulated signal by demodulating an intermediate frequency signal applied to said detector, said intermediate frequency signal comprising a relatively wideband video signal and an audio signal and said demodulated signal containing a luminance signal, a chrominance signal and a difference signal having a frequency which is the difference between the intermediate frequency of said video signal and the intermediate frequency of said audio signal, an improved video signal circuit comprising: an emitter follower circuit connected to receive said demodulated signals; and a trap circuit for trapping said difference signal at the emitter of said emitter follower circuit wherein the output of said trap circuit is connected to a load, said load, as seen by the output of said tRap, being adjustable to emphasize a relatively narrow band of preselected video signal frequencies less than the frequency of said difference signal.
Claim 3
Dependent Claim
72 words
The circuit of claim 1 wherein said trap circuit has an input and an output, said input being connected to the emitter of said emitter follower circuit and wherein said trap circuit further comprises: first and second capacitances connected in series and having a terminal mediate said capacitances; an inductance connected in parallel with said series connection of said capacitances: and a compensating resistance connected between said terminal and a common point.
Claim 4
Dependent Claim
176 words
In a television receiver having a detector circuit for detecting relatively broad band video signals from intermediate frequency signals representing video and audio signals, a circuit for attenuating a difference signal which has a frequency which is the difference between the frequencies of said intermediate frequency signals comprising: a transistor having an input signal derived from said detector output and applied to the base-emitter junction thereof; a trap circuit having an input and an output and comprising an inductance, a first capacitance, a second capacitance and a resistance, said capacitances connected in series and having a terminal mediate said capacitances, said inductance connected across the series connection of said capacitances and said resistance connected between said mediate terminal and a common terminal, said input of said trap circuit connected at the emitter of said transistor; and a load connected to the output of said trap, said load, as seen by the output of said trap, being adjustable to emphasize a relatively narrow band of preselected video signal frequencies less than the frequency of said difference signal.
Claim 5
Dependent Claim
176 words
In a television receiver having a detector circuit for detecting relatively broad band video signals from intermediate frequency signals representing video and audio signals, a circuit for attenuating a difference signal which has a frequency which is the difference between the frequencies of said intermediate frequency signals comprising: a transistor having an input signal derived from said detector output and applied to the base-emitter junction thereof; a trap circuit having an input and an output and comprising an inductance, a first capacitance, a second capacitance and a resistance, said capacitances connected in series and having a terminal mediate said capacitances, said inductance connected across the series connection of said capacitances and said resistance connected between said mediate terminal and a common terminal, said input of said trap circuit connected at the emitter of said transistor; and a load connected to the output of said trap, said load, as seen by the output of said trap, being adjustable to emphasize a relatively narrow band of preselected video signal frequencies less than the frequency of said difference signal.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-12-02 | 1978-06-03 | 1978-12-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-12-02 | 1982-06-03 | 1982-12-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-12-02 | 1986-06-03 | 1986-12-03 | $7700.00 | Window Closed / Lapsed |