Automatic degaussing circuit for tv having half-wave voltage doubler power supply

Claim 2

In a color television receiver adapted to receive energy from a pair of alternating voltage line input terminals, the combination comprising: a transformerless voltage doubler type B+ supply including: a pair of diodes, each having a pair of electrodes; an alternating current coupling network linking dissimilar electrodes of said pair of diodes to one of said input terminals; a first capacitor coupled between the remaining electrode of one of said diodes and the remaining electrode of the other of said diodes; means for connecting said remaining electrode of said one diode to the other of said input terminals; and wherein said alternating current coupling network includes: a second capacitor and a first thermistor connected in series between said one input terminal and said dissimilar electrodes; a third capacitor and a second thermistor connected in series across the series combination of said second capacitor and first thermistor; a voltage dependent resistor and a degaussing coil connected in series across said second thermistor; said first and second thermistors having negative temperature coefficients and substantially matched thermal characteristics; and the sum of the capacitance values for said second and third capacitors exceeding the capacitance value of said first capacitor.

Claim 3

In a color television receiver including a color kinescope subject to undesired magnetizations, a degaussing coil structure for eliminating said undesired magnetizations when suitably energized with alternating current of an initially large magnitude which subsequently diminishes in a smoothly tapering manner to an insignificant magnitude; receiver circuitry requiring an operating potential of a unidirectional character; a pair of power input terminals; and power coupling apparatus adapted, when the receiver is placed in operation, to supply an alternating voltage input across said input terminals, the alternating voltage having a peak amplitude smaller than the amplitude of the unidirectional operating potential required by said receiver circuitry; apparatus for developing said unidirectional potential and for providing said suitable energization of said degaussing coil structure, comprising the combination of: an alternating current coupling network including a first storage capacitor; a first diode connected in series with said alternating current coupling network across said power input terminals; a second diode; a second storage capacitor; means for serially connecting said second diode and said second storage capacitor, in the order named, across said first diode in such manner said first and second diodes are oppositely poled with respect to alternating current coupled by said network, said unidirectional operating potential required by said receiver circuitry being derived from the potential appearing across said second storage capacitor; said alternating current coupling network presenting a first alternating current path between one of said input terminals and said first diode which includes said first storage capacitor in series with the parallel combination of first and second current conveying circuit branches, said first current conveying circuit branch including a voltage dependent resistor in series with said degaussing coil structure, said second current conveying circuit branch including a first thermistor having a negative temperature coefficient, said first thermistor cooperating with said voltage dependent resistor to control the division of current between said first and second current conveying circuit branches so that initially, upon placing of said receiver in operation, a substantial portion of the current passed by said first storage capacitor flows in said first current conveying circuit branch including Said degaussing coil structure, and subsequently a substantial portion of the current passed by said first storage capacitor is bypassed around said degaussing coil structure via said second current conveying circuit branch including said first thermistor; a third storage capacitor; said alternating current coupling network additionally presenting a second alternating current path in parallel with said first alternating current path between said one input terminal and said first diode which includes said third storage capacitor; and current controlling means, comprising a second thermistor having a negative temperature coefficient disposed in series with said third capacitor in said second alternating current path, for initially, upon placing of said receiver in operation, precluding substantial current flow in said second path and subsequently permitting substantial current flow in said second path.

Claim 4

In a color television receiver including a color kinescope subject to undesired magnetizations, a degaussing coil structure for eliminating said undesired magnetizations when suitably energized with alternating current of an initially large magnitude which subsequently diminishes in a smoothly tapering manner to an insignificant magnitude; receiver circuitry requiring an operating potential of a unidirectional character; a pair of power input terminals; and power coupling apparatus adapted, when the receiver is placed in operation, to supply an alternating voltage input across said input terminals, the alternating voltage having a peak amplitude smaller than the amplitude of the unidirectional operating potential required by said receiver circuitry; apparatus for developing said unidirectional potential and for providing said suitable energization of said degaussing coil structure, comprising the combination of: an alternating current coupling network including a first storage capacitor; a first diode connected in series with said alternating current coupling network across said power input terminals; a second diode; a second storage capacitor; means for serially connecting said second diode and said second storage capacitor, in the order named, across said first diode in such manner said first and second diodes are oppositely poled with respect to alternating current coupled by said network, said unidirectional operating potential required by said receiver circuitry being derived from the potential appearing across said second storage capacitor; said alternating current coupling network presenting a first alternating current path between one of said input terminals and said first diode which includes said first storage capacitor in series with the parallel combination of first and second current conveying circuit branches, said first current conveying circuit branch including a voltage dependent resistor in series with said degaussing coil structure, said second current conveying circuit branch including a first thermistor having a negative temperature coefficient, said first thermistor cooperating with said voltage dependent resistor to control the division of current between said first and second current conveying circuit branches so that initially, upon placing of said receiver in operation, a substantial portion of the current passed by said first storage capacitor flows in said first current conveying circuit branch including Said degaussing coil structure, and subsequently a substantial portion of the current passed by said first storage capacitor is bypassed around said degaussing coil structure via said second current conveying circuit branch including said first thermistor; a third storage capacitor; said alternating current coupling network additionally presenting a second alternating current path in parallel with said first alternating current path between said one input terminal and said first diode which includes said third storage capacitor; and current controlling means, comprising a second thermistor having a negative temperature coefficient disposed in series with said third capacitor in said second alternating current path, for initially, upon placing of said receiver in operation, precluding substantial current flow in said second path and subsequently permitting substantial current flow in said second path.

Claim 5

Apparatus in accordance with claim 2 wherein said first and second thermistors have substantially matched characteristics and are provided with a common thermal environment.