Rca Inc.

William V Fitzgerald

Ronald E Fernsler

Kevin E Nortrup

An input signal for controlling a television power supply has 'power-on' and 'power-off' signal states. When the input signal is in the 'power-on' state, it couples a clock signal to a primary winding of a transformer causing an alternating current voltage that is conductively isolated from the input signal to be developed across a secondary winding of the transformer. When the input signal is in the 'power-off' state, it decouples the clock signal from the primary winding so that no alternating current voltage is developed across the secondary winding. The signal across the secondary winding is demodulated in a demodulator that produces a control signal that is conductively isolated from the input signal. The control signal is coupled to a regulator of the power supply. A power-on state of the control signal occurs when the alternating current voltage is developed at the secondary winding terminal. A power-off state of the control signal occurs when the alternating current voltage is absent.

Video apparatus for generating a conductively isolated control signal

The raster scanned by a television receiver deflection circuit is subject to an increase in size resulting from a decrease in high voltage level caused by increasing electron beam current. The receiver comprises a switched mode power supply producing a voltage supply that is used to power the deflection circuit and generate the high voltage. The voltage supply level incorporates an ac ripple component caused by loading on the supply due to increasing beam current. A peak detector senses the peak level of the voltage supply and applies it to a regulator control circuit which maintains the peak level of the supply voltage constant. Increasing beam current loads the supply, decreasing the average dc voltage level applied to the deflection circuit, thereby decreasing the electron beam scan to compensate for a reduction in high voltage level.

Television receiver power supply regulation responding to beam current

A regulated power supply for a television receiver includes a transformer having a primary winding coupled to a source of unregulated voltage. A transistor switch controls the interval during which the unregulated voltage causes current to flow in the primary winding. By transformer action, power is transferred to secondary windings which are coupled to receiver load circuits. The secondary winding voltages are regulated by control of the primary winding conduction interval. A supplemental winding is layer wound over the primary winding to transfer additional power to the load circuits. The primary winding may be electrically isolated from the secondary windings and from the supplemental winding.

Regulated power supply incorporating a power transformer having a

In a color television receiver, field rate sawtooth current waves are supplied to vertical deflection windings by a vertical deflection output amplifier. The series combination of a deflection current sampling resistor and a DC blocking capacitor, coupled between the low potential terminal of the vertical deflection windings and a point of reference potential, is traversed by the field rate sawtooth current waves. The voltage across the series combination, comprising the sum of a field rate sawtooth voltage component and a field rate parabolic voltage component, is used as the drive voltage for the input winding of a saturable reactor effecting side pincushion distortion correction. The deflection current representative voltage developed by the sampling resistor is also utilized for a linearizing feedback purpose. The capacitor also serves a filtering function for the energizing potential supplied to the output amplifier.

Side pincushion correction circuit

A resonant retrace vertical deflection circuit comprises a retrace capacitor which forms a resonant circuit with the yoke vertical deflection windings during retrace of the electron beams. One or more diodes isolate the yoke from the circuit power supply to allow the yoke voltage to increase beyond the level of the supply to provide faster retrace. A second power supply is provided to precharge the retrace capacitor prior to retrace, resulting in a further decrease in retrace time.

Vertical deflection circuit

In a television receiver having a vertical oscillator for providing a source of vertical deflection signals to a vertical deflection circuit, a service switch having normal and service positions is coupled to the vertical oscillator through an interference isolating diode. In the normal position, the diode is reverse biased, allowing the oscillator to function normally while eliminating the introduction of signal interference into the oscillator. While in the service position, the switch causes the diode to become forward biased, thereby disabling the oscillator and collapsing the vertical scan.

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Indianapolis, IN, United States of America

William V Fitzgerald