Cathode ray tube {37 set-up{38 {0 circuitry

Claim 2

In a color television receiver employing a color cathode ray tube having a plurality of electron guns each providing an electron beam and having a cathode electrode, a magnitude alterable video signal source, a chrominance signal source, a potential source, and electron beam deflection means, control circuit apparatus comprising: first circuit branch means including a first switching means for selective coupling of a contact to said potential source and to said magnitude alterable video signal source; a plurality of ''''null'''' circuit means each coupled to said contact of said switching means and including an alterable impedance; and a plurality of second circuit branch means each having a junction coupled to one of said ''''null'''' circuit means at an end of said alterable impedance opposite to said coupled contact, each of said junctions being coupled by an electron device to said potential source and to said chrominance signal source and to one of said cathode electrodes and by an impedance to a potential reference level whereby a potential is developed at each of said junctions which is substantially equal to a potential appearing at said contact for a ''''black level'''' setting of said video signal source thereby inhibiting current flow through said ''''null'''' circuit means.

Claim 3

The control circuit apparatus of claim 1 wherein is included a voltage divider means coupled intermediate said potential source and a potential reference level with said first switching means selectively disconnecting said contact from said video signal source means and to said voltage divider whereby a potentiAl is applied to said contact having a value substantially equal to the potential developed at each junction of said second circuit branch means whereupon current flow through said alterable impedance of each of said ''''null'''' circuit means is inhibited.

Claim 4

The control circuit apparatus of claim 1 including a second switching means formed for cooperative action with said first switching means and coupled to said electron beam deflection means to effect enablement of electron beam scanning in a vertical direction upon selective coupling of said contact to said video signal source by said first switching means and disablement of electron beam scanning in a vertical direction upon disconnection of said contact and video signal source by said switching means.

Claim 5

The control circuit apparatus of claim 1 wherein each of said electron devices includes an output circuit coupled to a cathode electrode of an individual electron gun of a color cathode ray tube, a first input circuit coupled to said chrominance signal source, and a second input circuit coupled to one of said ''''null'''' arms having an alterable impedance therein whereby variation in said alterable impedance are applied to the signal input circuit of each of said electron devices.

Claim 6

Control circuit apparatus for a color television receiver having a color cathode ray tube with a plurality of electron guns each having a cathode electrode, a magnitude alterable video signal source, a chrominance signal source, a potential source, and means for deflection of electron beams from said electron guns in two normal directions comprising: first switching means having a contact formed for selective connection to and disconnection from said potential source and said magnitude alterable video signal source; a plurality of ''''null'''' arm means each having an alterable impedance and connected in parallel to said contact of said first switching means; a plurality of circuit means each having an electron device with an output circuit coupled to said potential source and to a cathode electrode of one of said electron guns, a first input circuit coupled to said chrominance signal source, and a second input electrode coupled to one of said plurality of parallel connected ''''null'''' arms and to an impedance coupled to a potential reference level; and second switching means coupled to said means for deflection of electron beams from said electron guns in two normal directions and ganged to said first switching means for cooperative operation therewith to effect enablement and disablement of vertical deflection of said electron beams in accordance with connection to and disconnection from said video signal source of said contact of said first switching means.

Claim 7

Control circuit apparatus for a color television receiver having a color cathode ray tube with a plurality of electron guns each having a cathode electrode, a magnitude alterable video signal source, a chrominance signal source, a potential source, and means for deflection of electron beams from said electron guns in two normal directions comprising: first switching means having a contact formed for selective connection to and disconnection from said potential source and said magnitude alterable video signal source; a plurality of ''''null'''' arm means each having an alterable impedance and connected in parallel to said contact of said first switching means; a plurality of circuit means each having an electron device with an output circuit coupled to said potential source and to a cathode electrode of one of said electron guns, a first input circuit coupled to said chrominance signal source, and a second input electrode coupled to one of said plurality of parallel connected ''''null'''' arms and to an impedance coupled to a potential reference level; and second switching means coupled to said means for deflection of electron beams from said electron guns in two normal directions and ganged to said first switching means for cooperative operation therewith to effect enablement and disablement of vertical deflection of said electron beams in accordance with connection to and disconnection from said video signal source of said contact of said first switching means.

Claim 8

The control circuit apparatus of claim 5 wherein said contact of said first switching means is coupled to said potential source and selectively connected to said video signal source and to an impedance coupled to a potential reference level.

Claim 9

The control circuit apparatus of claim 5 wherein the potential appearing at each of the plurality of impedance, ''''null'''' arm, and electron device coupling is substantially equal to the potential appearing at said contact of said first switching means when said magnitude alterable video signal source is adjusted to a ''''black level'''' setting.