US3707597A — Video blanking and audio muting circuit

Claim 1

Independent Claim 251 words

In a television receiver employing an audio output stage including a sound reproducing device responsive to applied audio frequency signals, a video output stage including an image reproducing kinescope in which beam current flows as a function of the setting of an included brightness control coupled to vary a bias voltage on an electrode thereof, first apparatus for varying the amplitude of audio frequency signals within said audio output stage for application to and reproduction by said device according to individual viewer preference, second apparatus, operable with said image reproducing kinescope, for limiting the beam current which flows as said brightness control is varied to a predetermined level, and a detenting channel selector, the combination therewith of: transistor means coupled to said first apparatus and operative to reduce the amplitude of audio frequency signals within said output stage in response to a first provided control signal to correspondingly reduce the amplitude of signals applied to said sound reproducing device in a direction to de-activate said device; rectifier means coupled to said second apparatus and operative to reduce the level to which said beam current can flow as said brightness control is varied in response to a second provided control signal to correspondingly reduce the resultant bias on said kinescope electrode in a direction to de-activate said image reproducing kinescope; and switch means operative in conjunction with said detenting channel selector to provide at least one of said first and second control signals when said selector is changed to an unprogrammed channel.

Claim 2

Dependent Claim 251 words

In a television receiver employing an audio output stage including a sound reproducing device responsive to applied audio frequency signals, a video output stage including an image reproducing kinescope in which beam current flows as a function of the setting of an included brightness control coupled to vary a bias voltage on an electrode thereof, first apparatus for varying the amplitude of audio frequency signals within said audio output stage for application to and reproduction by said device according to individual viewer preference, second apparatus, operable with said image reproducing kinescope, for limiting the beam current which flows as said brightness control is varied to a predetermined level, and a detenting channel selector, the combination therewith of: transistor means coupled to said first apparatus and operative to reduce the amplitude of audio frequency signals within said output stage in response to a first provided control signal to correspondingly reduce the amplitude of signals applied to said sound reproducing device in a direction to de-activate said device; rectifier means coupled to said second apparatus and operative to reduce the level to which said beam current can flow as said brightness control is varied in response to a second provided control signal to correspondingly reduce the resultant bias on said kinescope electrode in a direction to de-activate said image reproducing kinescope; and switch means operative in conjunction with said detenting channel selector to provide at least one of said first and second control signals when said selector is changed to an unprogrammed channel.

Claim 3

Dependent Claim 81 words

The combination of claim 1 wherein said first means includes a transistor having base, emitter and collector electrodes, and which is relatively ineffective in reducing the amplitude of audio frequency signals within said output stage in the absence of said first control Signal but which substantially reduces the amplitude of said audio frequency signals when said first control signal is provided and applied to its base electrode and its emitter and collector electrodes are coupled in circuit with said first apparatus.

Claim 4

Dependent Claim 99 words

The combination of claim 2 wherein said first apparatus includes a manually controllable attenuator circuit for developing said audio frequency signal for application to said sound reproducing device in accordance with said viewer preference, and wherein the emitter electrode-collector electrode current path of said transistor is coupled serially to said attenuator circuit to electronically reduce the amplitude of audio frequency signals within said output stage to correspondingly reduce the amplitude of said applied signal in a direction to de-activate said sound reproducing device when said first control signal is provided and applied to the base electrode of said transistor.

Claim 5

Dependent Claim 94 words

The combination of claim 1 wherein said second means includes a rectifier having anode and cathode electrodes, and being in a first conductive condition to be relatively ineffective in reducing the level to which said beam current can flow as said brightness control is varied and the resulting bias on said kinescope electrode in the absence of said second control signal but being in a second conductive condition to substantially reduce said level and said resultant bias on said kinescope electrode when said second control signal is provided and applied to its cathode electrode.

Claim 6

Dependent Claim 77 words

The combination of claim 4 wherein said second apparatus includes a beam current limiter circuit having a manual control coupled to said kinescope electrode and wherein the anode electrode of said rectifier is coupled to said beam current limiter circuit to electronically reduce the voltage at said control and the bias on said kinescope electrode to deactivate said image reproducing kinescope when said second control signal is provided and applied to the cathode electrode of said rectifier.

Claim 7

Dependent Claim 36 words

The combination of claim 1 wherein said switch means operates in conjunction with said detenting channel selector to provide both said first and second control signals when said selector is manually changed to an unprogrammed channel.

Claim 8

Dependent Claim 109 words

The combination of claim 3 wherein the emitter electrode of said transistor is coupled to a manually controllable attenuator circuit, wherein the base electrode of said transistor is coupled to a point of reference potential by a second resistor and to a source of bias potential by third and fourth resistors coupled in series, and wherein said switch means provides said first control signal to the junction of said third and fourth resistors for causing a change in the voltage developed at the collector electrode of said transistor in a direction to reduce the amplitude of audio frequency signals coupled by said attenuator circuit to said sound reproducing device.

Claim 9

Dependent Claim 80 words

The combination of claim 5 wherein the cathode electrode of said rectifier is coupled by a first resistor to a source of bias potential which reverse biases said rectifier, and wherein said switch means provides said second control signal to the cathode electrode of said rectifier to forward bias said rectifier and cause a change in the voltage developed at said brightness limiter control in a direction to reduce the bias voltage coupled by said control to said kinescope electrode.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1975-12-26	1976-06-26	1976-12-26	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1979-12-26	1980-06-26	1980-12-26	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1983-12-26	1984-06-26	1984-12-26	$7700.00	Window Closed / Lapsed

Video blanking and audio muting circuit

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