Kinescope bias tracking circuits

Claim 2

In a television receiver having a luminance amplifier chain with an output direct coupled to a cathode electrode of a kinescope and a clamping circuit associated with a kinescope grid electrode for restoring the same to a DC potential with respect to that potential on the cathode to provide a predetermined potential difference therebetween, said cathode electrode as coupled to said luminance amplifier subject to a change in quiescent potential due to fluctuations of an unregulated power supply energizing that portion of said luminance amplifier driving said cathodes, said clamping circuit being biased from said unregulated supply and operated by a pulse formed by deflection circuitry included iN said receiver during a horizontal retrace interval, which pulse amplitude is also effected by said fluctuations, said fluctuations of said pulse amplitude together with said unregulated bias source serving to combine to eliminate said fluctuations from affecting said grid electrode potential as clamped by said circuit, thereby causing said cathode to grid potential to vary according to the affects of said fluctuations on said cathode electrode, in combination, therewith, means coupled between said unregulated power supply and said clamping circuit responsive to said pulse amplitude as compared to said unregulated power supply potential for regulating said pulse amplitude at a given specified level, whereby said clamped kinescope grid electrode potential varies only according to said unregulated bias source, as does said cathode potential, to maintain said grid to cathode potential relatively constant with said fluctuations.

Claim 3

Apparatus for use in a color television receiver employing a kinescope having at least one control electrode thereof AC coupled to a source of video information, comprising: a. a transistor having a base, collector and emitter electrode; b. A source of unregulated potential; c. a resistor divider coupled between said collector electrode of said transistor and said source of unregulated potential, for supplying an operating potential thereto; d. means for returning the base electrode of said transistor to a point of reference potential, to bias said transistor in a normally nonconducting state; e. a network, including a series resistor and diode coupled between a point on said resistor divider and said unregulated source, the junction between said resistor and diode coupled to said control electrode of said kinescope, which electrode is AC coupled to said source of video information; f. voltage regulating means having two terminals, one terminal thereof coupled to said unregulated source and said other terminal coupled to said collector electrode, said regulator thus being in shunt with said resistor divider; g. means coupled to said emitter electrode for pulsing said transistor into current conduction in a direction to cause said voltage regulator to maintain a fixed potential pulse across said resistor divider and therefore across said series network whereby any fluctuations due to variations of potential level of said unregulated supply do not effect said pulse amplitude as applied to said junction between said series resistor and diode.

Claim 4

Apparatus for use in a color television receiver employing a kinescope having at least one control electrode thereof AC coupled to a source of video information, comprising: a. a transistor having a base, collector and emitter electrode; b. A source of unregulated potential; c. a resistor divider coupled between said collector electrode of said transistor and said source of unregulated potential, for supplying an operating potential thereto; d. means for returning the base electrode of said transistor to a point of reference potential, to bias said transistor in a normally nonconducting state; e. a network, including a series resistor and diode coupled between a point on said resistor divider and said unregulated source, the junction between said resistor and diode coupled to said control electrode of said kinescope, which electrode is AC coupled to said source of video information; f. voltage regulating means having two terminals, one terminal thereof coupled to said unregulated source and said other terminal coupled to said collector electrode, said regulator thus being in shunt with said resistor divider; g. means coupled to said emitter electrode for pulsing said transistor into current conduction in a direction to cause said voltage regulator to maintain a fixed potential pulse across said resistor divider and therefore across said series network whereby any fluctuations due to variations of potential level of said unregulated supply do not effect said pulse amplitude as applied to said junction between said series resistor and diode.

Claim 5

The apparatus according to claim 2 wherein, said voltage regulating means comprises a zener diode having an anode electrode coupled to said collector electrode and a cathode electrode coupled to said unregulated source.

Claim 6

In a color television receiver employing a color kinescope having cathode and grid electrodes for determining a specified amount of beam current drawn by said kinescope as a function of the potential difference between said grid and cathode electrodes, means for direct coupling said cathode to a source of luminance signals, said means including a transistor whose base electrode drive is constant but whose collector operating potential is derived from an unregulated source capable of exhibiting variations in said operating potential as a function of AC line variations, said grid electrodes capacitively coupled to color demodulators and direct coupled to synchronous clamping circuits each comprising a diode and resistor connected between said unregulated source and a first terminal, the junction between the anode of said diode and said resistor being coupled to said grid electrode said clamps when operated by a suitable amplitude pulse, function to charge said capacitors coupling said color demodulators to a predetermined DC potential, in combination therewith, comprising: a. A transistor having a base, collector and emitter electrode; b. means coupling said collector electrode to said unregulated source and said first terminal; c. means coupled to said base electrode for biasing said transistor in a normally nonconducting state; d. a voltage reference device coupled in shunt with said unregulated source and said first terminal; and e. means coupled to said emitter electrode of said transistor for pulsing said transistor to a conducting state in a direction to cause said voltage reference device to operate to maintain any potential variation, due to said said conduction, constant between said unregulated source and said first terminal, whereby said grid to cathode potential difference of said kinescope remains substantially constant.

Claim 7

In a color television receiver employing a color kinescope having cathode and grid electrodes for determining a specified amount of beam current drawn by said kinescope as a function of the potential difference between said grid and cathode electrodes, means for direct coupling said cathode to a source of luminance signals, said means including a transistor whose base electrode drive is constant but whose collector operating potential is derived from an unregulated source capable of exhibiting variations in said operating potential as a function of AC line variations, said grid electrodes capacitively coupled to color demodulators and direct coupled to synchronous clamping circuits each comprising a diode and resistor connected between said unregulated source and a first terminal, the junction between the anode of said diode and said resistor being coupled to said grid electrode said clamps when operated by a suitable amplitude pulse, function to charge said capacitors coupling said color demodulators to a predetermined DC potential, in combination therewith, comprising: a. A transistor having a base, collector and emitter electrode; b. means coupling said collector electrode to said unregulated source and said first terminal; c. means coupled to said base electrode for biasing said transistor in a normally nonconducting state; d. a voltage reference device coupled in shunt with said unregulated source and said first terminal; and e. means coupled to said emitter electrode of said transistor for pulsing said transistor to a conducting state in a direction to cause said voltage reference device to operate to maintain any potential variation, due to said said conduction, constant between said unregulated source and said first terminal, whereby said grid to cathode potential difference of said kinescope remains substantially constant.

Claim 8

The combination according to claim 4 wherein said means coupled to said base electrode is a resistor and a capacitor in shunt, connected between said base electrode and a point of reference potential.

Claim 9

The combination according to claim 5 further comprising a resistor connected between the collector electrode of said transistor and a point of reference potential, and of a magnitude selected to prevent collector to emitter breakdown of said transistor when being pulsed to said conductive state.

Claim 10

The combination according to claim 5 further comprising: a. a capacitor coupled in parallel with said voltage reference device; and b. a diode in series with said voltage reference device and said collector electrode of said transistor, said capacitor and diode serving to inhibit radiation from said device when caused to operate due to said transistor conducting.

Claim 11

Apparatus for use in a television receiver, comprising: a. a low level amplifier responsive to luminance information contained in a composite video signal, said amplifier operated from a low voltage regulated supply for providing at an output thereof a relatively constant amplitude luminance signal; b. a second amplifier having an input coupled to said output of said low level amplifier and operated from a substantially high voltage nonregulated supply for providing at an output thereof a larger amplitude level luminance signal; c. a kinescope, having at least a cathode and grid electrode, said cathode electrode being direct coupled to said output of said second amplifier electrode used for driving said cathode electrode and for quiescently biasing the same from said unregulated supply to cause said cathode potential to vary with any variations of said nonregulated supply; d. a source of color difference signals capacitively coupled to said grid electrode of said kinescope for signal driving said grid electrode; e. clamping means coupled between said unregulated supply and said grid electrode for charging said capacitive coupling to restore a DC bias to said grid electrode when operated by a suitable amplitude and polarity pulse, said restored DC bias determined by any variations in said nonregulated supply and said pulse amplitude; and f. means coupled between said clamping means and said nonregulated supply for pulsing said clamping means into operation with a suitable polarity pulse whose amplitude is substantially constant and independent of any fluctuations in said potential of said unregulated supply, whereby said bias on said grid electrode as DC restored by said clamp varies only with said any variations of said nonregulated supply as does said cathode electrode.

Claim 12

Apparatus for use in a television receiver, comprising: a. a low level amplifier responsive to luminance information contained in a composite video signal, said amplifier operated from a low voltage regulated supply for providing at an output thereof a relatively constant amplitude luminance signal; b. a second amplifier having an input coupled to said output of said low level amplifier and operated from a substantially high voltage nonregulated supply for providing at an output thereof a larger amplitude level luminance signal; c. a kinescope, having at least a cathode and grid electrode, said cathode electrode being direct coupled to said output of said second amplifier electrode used for driving said cathode electrode and for quiescently biasing the same from said unregulated supply to cause said cathode potential to vary with any variations of said nonregulated supply; d. a source of color difference signals capacitively coupled to said grid electrode of said kinescope for signal driving said grid electrode; e. clamping means coupled between said unregulated supply and said grid electrode for charging said capacitive coupling to restore a DC bias to said grid electrode when operated by a suitable amplitude and polarity pulse, said restored DC bias determined by any variations in said nonregulated supply and said pulse amplitude; and f. means coupled between said clamping means and said nonregulated supply for pulsing said clamping means into operation with a suitable polarity pulse whose amplitude is substantially constant and independent of any fluctuations in said potential of said unregulated supply, whereby said bias on said grid electrode as DC restored by said clamp varies only with said any variations of said nonregulated supply as does said cathode electrode.