Video muting circuits

Claim 2

In a television receiver, including means for receiving any one of a plurality of transmitted radio frequency television signals, selectively operated means for processing any selected given one of said radio frequency signals and means for providing a video signal containing both a DC and AC component representative of a portion of a television picture content from said processed signal, said receiver including a kinescope, said kinescope having a control electrode for application thereto of a suitable signal for varying the brightness of a display on the viewing screen thereof and including means for selecting said means for processing to operate on a desired given one of said radIo frequency signals, in combination therewith, comprising: a. a video amplifier having an input responsive to said video signal and an output coupled to said control electrode of said kinescope for controlling said brightness according to both the AC and DC components of said video signal; b. switching means coupled to said selectively operated means to operate the same to select one of said radio frequency signals; c. a brightness biasing network coupled to said input of said video amplifier for controlling the DC operating point thereof and therefore the brightness of said kinescope display; and d. means connecting said brightness biasing network to said switching means for applying a biasing level to said video amplifier sufficient to blank said kinescope, when said selectively operated means is operated.

Claim 3

In a television receiver having a radio frequency section which by means, including a channel selector switch, is capable of receiving any desired one of a plurality of radio frequency television signals, said receiving including means for converting said any one radio frequency signal to a video signal, and a kinescope for producing a video display, said kinescope having a control electrode for applying a voltage thereto for controlling the brightness of said display in accordance with the magnitude of said voltage, in combination therewith: a. selectively operated means coupled to said channel selector switch for automatically driving said switch, to cause said receiver to be receptive to one of said radio frequency signals, when said selectively operated means is energized by a suitable operating potential; b. a source of operating potential of a magnitude sufficient to operate said selectively operated means; c. a switch coupled between said source and said selectively operated means to apply said operating potential to said selectively operated means in a first position and to remove said potential therefrom in a second position; d. a video amplifier, including a DC coupling path, said amplifier having an output coupled to said electrode of said kinescope and an input responsive to said video signal, for applying to said electrode both the AC and DC components of said video signal; e. a brightness supply including a voltage divider at an input thereof and having said input coupled to said source of operating potential and an output of said brightness supply coupled to said input of said video amplifier, said voltage divider supplying a potential to said brightness supply at said input which is less than said magnitude sufficient to operate said selectively operated means; and f. means coupled between said brightness supply and said switch to apply said full potential of said source to said brightness supply when said switch is operated in said first position, said potential being of a magnitude to blank said kinescope via said video amplifier.

Claim 4

In a television receiver having a radio frequency section which by means, including a channel selector switch, is capable of receiving any desired one of a plurality of radio frequency television signals, said receiving including means for converting said any one radio frequency signal to a video signal, and a kinescope for producing a video display, said kinescope having a control electrode for applying a voltage thereto for controlling the brightness of said display in accordance with the magnitude of said voltage, in combination therewith: a. selectively operated means coupled to said channel selector switch for automatically driving said switch, to cause said receiver to be receptive to one of said radio frequency signals, when said selectively operated means is energized by a suitable operating potential; b. a source of operating potential of a magnitude sufficient to operate said selectively operated means; c. a switch coupled between said source and said selectively operated means to apply said operating potential to said selectively operated means in a first position and to remove said potential therefrom in a second position; d. a video amplifier, including a DC coupling path, said amplifier having an output coupled to said electrode of said kinescope and an input responsive to said video signal, for applying to said electrode both the AC and DC components of said video signal; e. a brightness supply including a voltage divider at an input thereof and having said input coupled to said source of operating potential and an output of said brightness supply coupled to said input of said video amplifier, said voltage divider supplying a potential to said brightness supply at said input which is less than said magnitude sufficient to operate said selectively operated means; and f. means coupled between said brightness supply and said switch to apply said full potential of said source to said brightness supply when said switch is operated in said first position, said potential being of a magnitude to blank said kinescope via said video amplifier.

Claim 5

In combination with a television receiver of the type having a series connected filament string for energizing the filaments of a plurality of vacuum tubes utilized therein from a power line source, said receiver including a video amplifier having a DC path coupled to a control electrode of a kinescope for applying an amplified video signal to said electrode and for varying the brightness of the kinescope display in accordance with the biasing of said video amplifier, said receiver including a motor driven tuner, comprising: a. a switch coupled between said power line source and a terminal of said motor winding; b. a voltage divider coupled between a portion of said filament string and said motor winding, whereby a first potential level appears across said voltage divider when said switch is opened and a second potential appears across said divider when said switch is closed; and c. a brightness bias source including a rectifier coupled between said voltage divider and said video amplifier whereby said video amplifier receives said DC proportional to said first potential level when said switch is opened and a second DC proportional to said second potential level when said switch is closed, said second DC level being of a sufficient magnitude to blank said kinescope display.

Claim 6

In combination with a television receiver of the type having a series connected filament string for energizing the filaments of a plurality of vacuum tubes utilized therein from a power line source, said receiver including a video amplifier having a DC path coupled to a control electrode of a kinescope for applying an amplified video signal to said electrode and for varying the brightness of the kinescope display in accordance with the biasing of said video amplifier, said receiver including a motor driven tuner, comprising: a. a switch coupled between said power line source and a terminal of said motor winding; b. a voltage divider coupled between a portion of said filament string and said motor winding, whereby a first potential level appears across said voltage divider when said switch is opened and a second potential appears across said divider when said switch is closed; and c. a brightness bias source including a rectifier coupled between said voltage divider and said video amplifier whereby said video amplifier receives said DC proportional to said first potential level when said switch is opened and a second DC proportional to said second potential level when said switch is closed, said second DC level being of a sufficient magnitude to blank said kinescope display.

Claim 7

In combination with a television receiver of the type having a series connected filament string for energizing the filaments of a plurality of vacuum tubes utilized therein, from a power line source, said receiver including a video amplifier having a DC path coupled to a control electrode of a kinescope for applying an amplified video signal to said electrode and for varying the brightness of the kinescope display in accordance with the biasing of said video amplifier, said receiver including a motor having a field winding, said motor used for driving the receiver tuner, comprising: a. switching means operable in a first position for coupling said field winding of said motor to said power line source for energizing said motor and in a second normal position for inactivating said motor; b. a voltage divider coupled between a portion of said filament string and said motor winding; and c. a rectifier circuit having an input coupled to a portion of said voltage divider and an output coupled to said video amplifier, said rectifier circuit providing at said output a first DC potential for said first switching means position corresponding to the energization of said motor and a second DC potential for said second switch position, whereby said DC path of said video amplifier reduces said brightness of said kinescope display to blank said display when said switching means is in said first position and to permit a normal brightness raster to appear during said second switching means position.

Claim 8

In combination with a television receiver of the type having a series connected filament string for energizing the filaments of a plurality of vacuum tubes utilized therein, from a power line source, said receiver including a video amplifier having a DC path coupled to a control electrode of a kinescope for applying an amplified video signal to said electrode and for varying the brightness of the kinescope display in accordance with the biasing of said video amplifier, said receiver including a motor having a field winding, said motor used for driving the receiver tuner, comprising: a. switching means operable in a first position for coupling said field winding of said motor to said power line source for energizing said motor and in a second normal position for inactivating said motor; b. a voltage divider coupled between a portion of said filament string and said motor winding; and c. a rectifier circuit having an input coupled to a portion of said voltage divider and an output coupled to said video amplifier, said rectifier circuit providing at said output a first DC potential for said first switching means position corresponding to the energization of said motor and a second DC potential for said second switch position, whereby said DC path of said video amplifier reduces said brightness of said kinescope display to blank said display when said switching means is in said first position and to permit a normal brightness raster to appear during said second switching means position.