US3555182A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Plural operating mode automatic gain control system
Assignee: RCA Licensing Corp
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Filing: 1968-05-20
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Granted: 1971-01-12
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Expires: 1988-05-20
Abstract
Abstract An automatic gain control system for a television receiver employing a fixed biasing arrangement for a video detector, noise inverter, sync separator, and automatic gain control amplifier. The noise inverter operates when noise pulses exceed a threshold limit determined in part by the biasing arrangement. Relatively noise-free sync pulses therefore are supplied to the sync separator and AGC circuit. The AGC circuit is arranged to supply control voltages having different ranges to the R.F. and I.F. amplifiers in the receiver. Furthermore, the AGC circuit operates such that a reference video signal is supplied to the imagereproducing kinescope during a service operating mode.
Inventors
- 👤 Dal F Griepentrog
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 22:48
CPC Classifications
H; H04; H04N; H04N5/00; H04N5/44; H04N5/52; H04N5/53; H04N5/14; H04N5/21
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
230 words
In a television receiver having a source of composite television signals including image brightness representative signal components and regularly recurring synchronizing signal components extending in amplitude beyond said image brightness representative signal components, the combination comprising: automatic gain control means coupled to said source of composite signals for maintaining said synchronizing signal components at a substantially fixed level; noise threshold means coupled to said source of composite signals responsive to noise components exceeding said fixed level by a predetermined amount; a voltage divider including a plurality of resistive elements connected in a single series path between a first terminal adapted for application thereto of a source of stable operating potential and a second terminal coupled to a point of reference potential; means coupled to a first point on said voltage divider for supplying a first fixed reference voltage to said source of composite signals and for supplying a second fixed reference voltage available at a second point on said divider, to each of said noise threshold and automatic gain control means, whereby said divider provides a common bias and current path for said source of composite signals, said automatic gain control means and said noise threshold means, for establishing said fixed level; a synchronizing signal separator circuit; and means for coupling said noise threshold means to each of said automatic gain control means and to said synchroniziNg signal separator circuit.
Claim 2
Dependent Claim
230 words
In a television receiver having a source of composite television signals including image brightness representative signal components and regularly recurring synchronizing signal components extending in amplitude beyond said image brightness representative signal components, the combination comprising: automatic gain control means coupled to said source of composite signals for maintaining said synchronizing signal components at a substantially fixed level; noise threshold means coupled to said source of composite signals responsive to noise components exceeding said fixed level by a predetermined amount; a voltage divider including a plurality of resistive elements connected in a single series path between a first terminal adapted for application thereto of a source of stable operating potential and a second terminal coupled to a point of reference potential; means coupled to a first point on said voltage divider for supplying a first fixed reference voltage to said source of composite signals and for supplying a second fixed reference voltage available at a second point on said divider, to each of said noise threshold and automatic gain control means, whereby said divider provides a common bias and current path for said source of composite signals, said automatic gain control means and said noise threshold means, for establishing said fixed level; a synchronizing signal separator circuit; and means for coupling said noise threshold means to each of said automatic gain control means and to said synchroniziNg signal separator circuit.
Claim 3
Dependent Claim
38 words
The combination according to claim 1 wherein: said source of composite television signals comprises means for detecting said brightness representative and synchronizing signal components; and said first point on said voltage divider being coupled to said detecting means.
Claim 4
Dependent Claim
41 words
The combination according to claim 2 and further comprising noise inverting means having an input alternating current coupled to said noise threshold means and an output direct current coupled to each of said automatic gain control and synchronizing signal separator circuits.
Claim 5
Dependent Claim
30 words
The combination according to claim 2 wherein said detecting means comprises a diode having anode and cathode electrodes, said diode being poled for conduction upon application of positive polarity signals.
Claim 6
Dependent Claim
21 words
The combination according to claim 4 wherein said source of stable operating potential provides a substantially constant voltage of positive polarity.
Claim 7
Dependent Claim
20 words
The combination according to claim 5 wherein said first fixed reference voltage is less than said second fixed reference voltage.
Claim 8
Dependent Claim
42 words
The combination according to claim 6 and further comprising noise inverting means having an input alternating current coupled to said noise threshold means and an output circuit direct current coupled to each of said automatic gain control and synchronizing signal separator circuits.
Claim 9
Dependent Claim
56 words
The combination according to claim 7 wherein said detecting means comprises a diode having anode and cathode electrodes; said diode being poled for conduction upon application of positive polarity signals; said source of stable operating potential provides a substantially constant voltage of positive polarity; and said first reference voltage is less than said second reference voltage.
Claim 10
Dependent Claim
192 words
In a television receiver having a source of composite television signals which includes radio frequency and intermediate frequency amplifiers, the television signal being characterized by synchronizing signal components recurring at a regular rate and image brightness representative signal components, automatic gain control means comprising; a source of pulses recurring substantially at said synchronizing signal rate; gating circuit means coupled to said source of pulses, coupled to said source of composite signals and responsive jointly thereto to produce a gain control effect for maintaining said synchronizing signal components at a predetermined level; output circuit means coupled to said gating circuit means and to said source of composite television signals; said output circuit means comprising; means for limiting said gain control effect to a first voltage level of a first polarity for a first range of input signal levels to said radio frequency amplifier, to a second voltage level of opposite polarity for a second range of input signal levels to said radio frequency amplifier and for providing a gain control voltage which varies between said first and second voltage levels for a range of input signal levels between said first and second ranges.
Claim 11
Dependent Claim
192 words
In a television receiver having a source of composite television signals which includes radio frequency and intermediate frequency amplifiers, the television signal being characterized by synchronizing signal components recurring at a regular rate and image brightness representative signal components, automatic gain control means comprising; a source of pulses recurring substantially at said synchronizing signal rate; gating circuit means coupled to said source of pulses, coupled to said source of composite signals and responsive jointly thereto to produce a gain control effect for maintaining said synchronizing signal components at a predetermined level; output circuit means coupled to said gating circuit means and to said source of composite television signals; said output circuit means comprising; means for limiting said gain control effect to a first voltage level of a first polarity for a first range of input signal levels to said radio frequency amplifier, to a second voltage level of opposite polarity for a second range of input signal levels to said radio frequency amplifier and for providing a gain control voltage which varies between said first and second voltage levels for a range of input signal levels between said first and second ranges.
Claim 12
Dependent Claim
67 words
Automatic gain control means in accordance with claim 9 wherein said output circuit means comprises a diode, first voltage supply means coupled to aid diode and to said gating means, and second voltage supply means coupled to said diode, said first and second voltage supply means maintaining said diode in forward conduction and zener conduction conditions, respectively, for said first and second ranges of input signal levels.
Claim 13
Dependent Claim
51 words
Automatic gain control means in accordance with claim 10 and further comprising capacitive means for coupling said gating circuit means to said source of pulses and for coupling to said output circuit means, in response to said pulses, a voltage of opposite polarity with respect to said first voltage supply means.
Claim 14
Dependent Claim
49 words
Automatic gain control means in accordance with claim 11 wherein said first voltage supply means comprises a first source of voltage, voltage divider means coupled aCross said first source of voltage and having at least first and second junctions couple, respectively, to said diode and to said capacitive means.
Claim 15
Dependent Claim
51 words
Automatic gain control means in accordance with claim 12 wherein said diode comprises anode and cathode electrodes, said first voltage supply means being coupled to said anode, and said second voltage supply means being coupled to said cathode and arranged to supply a voltage less than that of said first source.
Claim 16
Dependent Claim
62 words
Automatic gain control means in accordance with claim 12 wherein said output circuit means further comprises amplifying means coupled to said capacitive means for supplying varying gain control voltage to said intermediate frequency amplifier so as to produce a varying gain therein for said first and second ranges and a substantially invariant gain for said range between said first and second ranges.
Claim 17
Dependent Claim
35 words
Automatic gain control means in accordance with claim 12 and further comprising adjustable biasing means coupled to said amplifying means and to said voltage divider means for adjustably selecting said first range of signal levels.
Claim 18
Dependent Claim
209 words
In a television receiver having a source of composite television signals which includes components; frequency and intermediate frequency amplifiers, the television signals being characterized by synchronizing signal components and image brightness representative components, automatic gain control means comprising: a source of pulses recurring substantially at the rate of said synchronizing signal components; gating circuit means coupled to said source of pulses, coupled to said source of composite signals and responsive jointly thereto to produce a gain control effect for maintaining said synchronizing signal components at a predetermined level; output circuit means coupled to said gating circuit means and to said source of composite television signals for supplying thereto gain control voltage to maintain said predetermined level; servicing supply means coupled to said gating circuit means for energizing said gating circuit means so as to reduce the gain of said source of composite signal; switching means for disabling said supply means in a normal operating condition and for energizing said supply means in a service operating condition; and voltage supply means including a voltage divider coupled to said gating circuit means and to said source of composite signals responsive to energization of said service in supply means for producing a reference output signal level at said source of composite signals.
Claim 19
Dependent Claim
209 words
In a television receiver having a source of composite television signals which includes components; frequency and intermediate frequency amplifiers, the television signals being characterized by synchronizing signal components and image brightness representative components, automatic gain control means comprising: a source of pulses recurring substantially at the rate of said synchronizing signal components; gating circuit means coupled to said source of pulses, coupled to said source of composite signals and responsive jointly thereto to produce a gain control effect for maintaining said synchronizing signal components at a predetermined level; output circuit means coupled to said gating circuit means and to said source of composite television signals for supplying thereto gain control voltage to maintain said predetermined level; servicing supply means coupled to said gating circuit means for energizing said gating circuit means so as to reduce the gain of said source of composite signal; switching means for disabling said supply means in a normal operating condition and for energizing said supply means in a service operating condition; and voltage supply means including a voltage divider coupled to said gating circuit means and to said source of composite signals responsive to energization of said service in supply means for producing a reference output signal level at said source of composite signals.
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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) | 1974-01-11 | 1974-07-13 | 1975-01-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-01-11 | 1978-07-13 | 1979-01-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-01-11 | 1982-07-13 | 1983-01-12 | $7700.00 | Window Closed / Lapsed |