Rca Inc.

Rca Licensing Corporation

Walter Truskalo

Anthony Troiano

Thomas F Nolan

A degaussing apparatus for a video display includes a degaussing coil and a source of degaussing current. A switching means is coupled to the degaussing coil and to the source for providing a path for degaussing current between the source and coil during a degaussing operation. First and second PTC elements, functioning as degaussing current reducing means, are coupled to the degaussing coil and to the switching means. The switching means produces alternate coupling of the first and second PTC elements to the degaussing coil with respect to successive degaussing operations.

Video display degaussing apparatus

In a resonant regulator power supply, a resonant circuit is coupled to a source of alternating input voltage that is controllable in operating frequency. A power transformer primary winding is coupled across the capacitive element of the resonant circuit for generating an output voltage across a secondary winding. A control circuit varies the operating frequency in a negative feedback loop to regulate the output voltage on the positive slope of the frequency characteristic curve. A frequency limiting circuit prevents the operating frequency from passing through the resonance frequency of the resonant circuit.

Frequency limited resonant regulator useful in, for example, a

An attenuator couples a parabolic voltage developed in a trace capacitance, to a focus electrode. The attenuator includes a phase compensation network that causes the phase of the parabolic voltage that is coupled to the focus electrode to be substantially the same relative to that of the parabolic voltage in the trace capacitor for any scan frequency that is selected from a range of frequencies.

Dynamic focus voltage with phase compensated adjustment

A dynamic focus voltage generating circuit for television generates a parabolic voltage at the horizontal rate that is responsive to a synchronizing signal. The parabolic voltage is generated from a sawtooth waveform having an upramping portion, a downramping portion and a flat portion such that only the length of the flat portion of the sawtooth waveform varies when the frequency of the synchronizing signal changes.

Parabolic voltage generating apparatus for television

A resonant degaussing circuit for a video display apparatus permits frequent degaussing during operation of the display apparatus. In order to provide effective degaussing for large screen cathode ray tubes, an inductor is connected in parallel with the degaussing coil. The inductor increases the degaussing resonant frequency so that a greater number of resonant cycles occur before the degaussing current decreases below a predetermined level.

Resonant degaussing for a video display system

A degaussing coil and a capacitance are coupled in a resonant circuit by a switch to effect degaussing of a kinescope. The capacitance is charged by a source of relatively high voltage. A control circuit controls the operation of the switch and is responsive to a change in operating voltage applied thereto for operating the switch to effect complete discharge of the capacitance in a relatively short interval.

Degaussing system arrangements

A dynamic focus circuit for a television display picture tube provides a focus voltage having scan rate modulation. The parabolically shaped voltage which is produced across the S-shaping capacitor in a deflection system is coupled by a transformer having a primary winding coupled between the junction of the S-shaping capacitor and the deflection winding and a power supply point having substantially the same average DC potential. Substantially no DC current flows through the transformer primary winding, which permits a relatively small transformer to be used without saturation of the magnetic core and without the need for a coupling capacitor for DC isolation.

Dynamic focus circuit

In a video display monitor having a multiple rate scanning capability, a synchronized switching power supply develops the regulated operating voltages for the monitor. A deflection circuit produces scanning current in a deflection winding and is capable of being operated at either one of two selectable scanning frequencies. A signal synchronously related to the scanning current, such as a retrace pulse voltage, is applied to the control circuit of the switching power supply. The control circuit generates a control signal from the retrace pulse voltage that is synchronously related to the scanning current and of a frequency that is unchanged when the deflection circuit is operated at either of the two selectable scanning frequencies. The output stage of the switching power supply responds to the control signal and produces switching operation at the unchanged frequency in synchronism with the scanning current.

Synchronized switching regulator for a multiple scanning frequency video

A self-regulating power supply for a television receiver includes a transformer with a primary winding coupled to a source of input voltage for developing an alternating polarity supply voltage across a secondary winding. The supply voltage is stepped up, rectified and filtered to develop an ultor accelerating potential for the picture tube of the television receiver. A ferroresonant or self-regulating load circuit includes a saturable reactor having a winding coupled to the transformer secondary winding to provide regulation of the supply voltage, and thus, regulation of the ultor accelerating potential. The transformer secondary winding and the saturable reactor winding each comprises two winding sections, with each section having a terminal coupled to a common reference point, such as chassis ground. This type of arrangement provides redundancy in the ferroresonant operation of the self-regulating load circuit to avoid excessive increase in supply voltage should a portion of the self-regulating load circuit become disconnected from the transformer secondary winding.

Television receiver power supply ferroresonant load circuit provided

Serially coupled first and second capacitors are charged from a DC source of unregulated input voltage through the primary winding of a flyback transformer of a horizontal deflection circuit. The voltage across the first capacitor is established as the voltage difference between the input voltage and the voltage across the second capacitor. The first capacitor functions as a trace capacitor for a horizontal deflection winding. A switch couples a trace voltage to the horizontal deflection winding to generate a trace deflection current. The switch also couples a first winding of a saturable reactor to the second capacitor to provide a capacitor discharge current path. A bias current flowing in a second winding of the saturable reactor varies the effective inductance of the first winding in response to energy level changes in the deflection circuit to control the voltage across the second capacitor.

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Titusville, NJ, United States of America

Walter Truskalo