US3569620A — Automatic video signal gain controlling apparatus

Claim 1

Independent Claim 233 words

In a television system, gain-controlling apparatus for automatically maintaining a desired amplitude level of a composite video signal including at least picture representative signals and horizontal and vertical blanking and synchronizing pulses, comprising: a gain-controlling amplifier having input, output and control circuits; means for impressing said composite video signal upon said amplifier input circuit; means for deriving from said amplifier output circuit an amplified sample of said composite video signal; means for clamping picture black representative portions of said video signal sample at a fixed reference potential; picture white representative video signal-detecting means responsive to said clamped video signal sample and including a white signal sampler operative to produce a first white signal sample wave having an amplitude representative of the excess of said white signal samples beyond said desired amplitude level and a second white signal sample wave having an amplitude which is the inverse of said first white signal sample wave amplitude; said detecting means further comprising signal-combining means coupled to receive said first and second white signal sample waves from said white signal sampler for producing a gaincontrol signal having an amplitude representing the greater one of said first and second white signal sample wave amplitudes; and means for impressing said gain-control signal upon the control circuit of said gain-controlling amplifier to automatically maintain the composite video signal in said amplifier output circuit at the desired substantially constant amplitude level.

Claim 2

Dependent Claim 233 words

In a television system, gain-controlling apparatus for automatically maintaining a desired amplitude level of a composite video signal including at least picture representative signals and horizontal and vertical blanking and synchronizing pulses, comprising: a gain-controlling amplifier having input, output and control circuits; means for impressing said composite video signal upon said amplifier input circuit; means for deriving from said amplifier output circuit an amplified sample of said composite video signal; means for clamping picture black representative portions of said video signal sample at a fixed reference potential; picture white representative video signal-detecting means responsive to said clamped video signal sample and including a white signal sampler operative to produce a first white signal sample wave having an amplitude representative of the excess of said white signal samples beyond said desired amplitude level and a second white signal sample wave having an amplitude which is the inverse of said first white signal sample wave amplitude; said detecting means further comprising signal-combining means coupled to receive said first and second white signal sample waves from said white signal sampler for producing a gaincontrol signal having an amplitude representing the greater one of said first and second white signal sample wave amplitudes; and means for impressing said gain-control signal upon the control circuit of said gain-controlling amplifier to automatically maintain the composite video signal in said amplifier output circuit at the desired substantially constant amplitude level.

Claim 3

Dependent Claim 69 words

Automatic video signal gain-controlling apparatus as defined in claim 1, said composite video signal also including a vertical interval test signal, and said apparatus additionally comprising: a mode gate coupled between said picture black representative signal-clamping means and said picture white representative signal-detecting means, said mode gate being selectively operable to impress upon said detecting means either one or both of said picture representative and vertical interval test signals.

Claim 4

Dependent Claim 48 words

Automatic video signal gain-controlling apparatus as defined in claim 1, wherein: said white signal sampler comprises a white signal-sampling device for producing said first white signal sample wave; and a white signal-inverting device coupled to said white signal-sampling device for producing said second white device coupled sample wave.

Claim 5

Dependent Claim 97 words

Automatic video signal gain-controlling apparatus as defined in claim 3, wherein; said white signal-sampling and inverting devices are opposite conductivity types of transistors, both connected for common emitter operation and having their respective emitter electrodes connected together; said clamped composite video signal sample being applied by coupling means to the base electrode of said white signal-sampling transistor, and the base electrode of said white signal inverter transistor being connected to a fixed reference potential; and said first and second white signal sample waves being developed at the collector electrodes of said white signal-sampling and inverting transistors respectively.

Claim 6

Dependent Claim 110 words

Automatic video signal gain-controlling apparatus as defined in claim 4, wherein: said signal combiner comprises a first pair of two like signal-translating devices having individual input circuits and haviNg an interconnection to provide a common output circuit; said first and second white signal sample waves being impressed upon the respective input circuits of said first pair of like signal-translating devices to render conducting that device receiving the larger amplitude one of said first and second signal sample waves; and said interconnection being such that the one of said first pair of like devices receiving the smaller amplitude one of said first and second white signal sample waves is rendered nonconducting.

Claim 7

Dependent Claim 68 words

Automatic video signal gain-controlling apparatus as defined in claim 5, wherein: said first pair of two like signal-translating devices of said combiner are transistors of the same conductivity type, each having its base electrode included in its input circuit and its emitter and collector electrodes included in its output circuit; and said interconnection comprising a coupling between like one of the output circuit electrodes of said respective transistors.

Claim 8

Dependent Claim 25 words

Automatic video signal gain-controlling apparatus as defined in claim 6, wherein: said interconnection comprises a coupling between the emitter electrodes of said respectivelike signal-translating transistors.

Claim 9

Dependent Claim 56 words

Automatic video signal gain-controllng apparatus as defined in claim 7, wherein: said gain-controlling amplifier is a differential arrangement of a second pair of two like signal-translating devices having an interconnection forming said input circuit, one of said devices being included in said output circuit and the other of said devices being included in said control circuit.

Claim 10

Dependent Claim 117 words

Automatic video signal gain-controlling apparatus as defined in claim 8, wherein: said second pair of two like signal-translating devices of said gain-controlling amplifier are transistors of the same conductivity type, each having base, emitter and collector electrodes; said interconnection comprising a coupling between the emitter electrodes of said second pair of transistors; means for impressing a fixed reference potential upon the base electrode of a first one of said second pair of transistors; said amplifier output circuit including the collector electrode of said first one of said second pair of transistors; and means for impressing said gain-control signal derived from said signal combiner upon the pass electrode of the second one of said second pair of transistors.

Claim 11

Dependent Claim 60 words

Automatic video signal gain-controlling apparatus as defined in claim 9, wherein: said coupling means by which said clamped composite video signal sample is applied to the base electrode of the white signal-sampling transistor of said white signal sampler includes means for impressing a biasing potential upon said base electrode to establish an operating threshold for said white signal sampling transistor.

Claim 12

Dependent Claim 40 words

Automatic video signal gain-controlling apparatus as defined in claim 10, wherein: said biasing potential impressing means is variable so as to adjust the white signal level at which said apparatus is rendered operative to automatically control the video signal gain.

Claim 13

Dependent Claim 191 words

Automatic video signal gain-controlling apparatus as defined in claim 11, said composite video signal also including a vertical interval test signal, and said apparatus additionally comprising: a mode gate including two transistors having their respective collector-to-emitter circuits effectively connectable in shunt with the video signal path between said picture black representative signal-clamping means and said picture white representative signal-detecting means; and selector means operable for rendering the collector-to-emitter circuit of a first one of said mode gate transistors conductive only during the occurrence of said vertical interval test signal, thereby impressing only the picture representative signal upon said white signal-detecting means, said selector means also being operable for rendering the collector-to-emitter circuit of the second one of said mode gate trAnsistors conductive at all times except during the occurrence of said vertical interval test signal, thereby impressing only said vertical interval test signal upon said white signal detecting means, said selector means additionally being operable for rendering the collector-to-emitter circuits of both of said first and second mode gate transistors nonconducting at all times, thereby impressing both of said picture representative and vertical interval test signals upon said white signal-detecting means.

Claim 14

Dependent Claim 72 words

Automatic video signal gain-controlling apparatus as defined in claim 12, wherein: said selector means includes a switch operable to impress a gating pulse received during the occurrence of said vertical interval test signal upon a selected one of three contacts, first and second ones of said contacts being connected to the respective base electrodes of said first and second mode gate transistors and a third one of said switch contacts being unconnected.

Claim 15

Dependent Claim 163 words

Automatic video signal gain-controlling apparatus as defined in claim 13, wherein: said gating pulse has a negative potential during the occurrence of said vertical interval test signal and a positive potential at all other times; said first mode gate transistor being a PNP type, whereby with said switch operated to said first contact only the negative potential portion of said gating pulse renders the collector-to-emitter circuit of said PNP transistor conductive, said PNP transistor being nonconductive at all other times; said second mode gate transistor being an NPN type, whereby with said switch operated to said second contact only the negative potential portion of said gating pulse renders the collector-to-emitter circuit of said NPN transistor nonconductive, said NPN transistor being conductive at all other times; and with said switch operated to said third contact said gating pulse is disconnected from the base electrodes of both of said PNP and NPN transistors, thereby rendering the collector-to-emitter circuits of both transistors nonconductive at all times.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1974-03-08	1974-09-07	1975-03-09	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1978-03-08	1978-09-07	1979-03-09	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1982-03-08	1982-09-07	1983-03-09	$7700.00	Window Closed / Lapsed

Automatic video signal gain controlling apparatus

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