Rca Inc.

John Charles Peer

David W Luz

Ronald E Fernsler

Wolfgang F Dietz

Robert Joseph Gries

Leroy W Nero

An electronic regulator produces a regulated direct voltage less than the raw direct voltage input. The load on the regulated output is the primary winding of the horizontal output transformer of a television horizontal deflection circuit. A secondary winding of the output transformer is connected in series with the source of raw direct voltage. An energy storage capacitor is coupled across the secondary winding, and charged therefrom by a gated rectifier. The regulated output voltage is taken across the raw direct voltage source and capacitor. An overvoltage protection circuit for protecting against fault conditions is provided. The protection circuit includes a diode coupled between the regulated output voltage terminal and the raw input voltage terminal. The diode is normally back-biased and becomes conductive when a fault condition makes the regulated voltage exceed the raw input voltage. A resistor in series with the secondary winding controls circulating currents in the event of an overvoltage fault.

Overvoltage protected de-boost regulator

An oscillator responsive to a control signal generates a first signal at a first rate at an output terminal. A first transistor is coupled to the output terminal and to a load circuit. Normal operation of the load circuit depends upon the first transistor switching conductive states at the first rate. A second complementary type conductivity transistor forms a complementary disabling latch with the first transistor. A fault signal activates the latch and prevents the first transistor from switching conductive states, thereby disabling normal load circuit operation.

Complementary latching disabling circuit

A start-up circuit for a television receiver includes a circuit for rectifying the AC line voltage and a filter for providing a smoothed DC voltage. When the receiver is turned on, an initial interval exists in which inrush current flows into the filter. A magnetically coupled winding of an inductor in the path of the inrush current develops an alternating current potential during the initial interval. This potential is rectified and provides a start-up operating voltage for the television receiver.

Inrush current start-up circuit for a television receiver

A voltage regulator provides a regulated B+ voltage to the horizontal deflection circuit of a television receiver. A positive feedback loop senses the load current drawn by the deflection circuit. The positive feedback voltage increases the magnitude of a reactive impedance component of the voltage regulator as the load current increases in order to maintain a substantially constant raster width.

Television raster width regulation circuit

A horizontal deflection circuit of a color television receiver includes a horizontal output transformer with a secondary winding across which a voltage is developed and includes a horizontal deflection winding coupled to a pincushion correction winding of a pincushion reactor. In response to the current flowing in the vertical deflection winding, the inductance of the pincushion correction winding varies in a manner providing for East-West pincushion distortion correction. For setup, in the service mode of operation, the vertical deflection circuit is disabled. A circuit, coupled to the pincushion reactor, adjusts the inductance of pincushion correction winding to compensate for a change in the inductance caused by disabling of the vertical deflection circuit for maintaining the voltage across the horizontal output transformer secondary winding substantially unchanged during setup.

Circuit for correcting setup error in a color television receiver

A push-pull amplifier, which is supplied with a first voltage, provides deflection current to a vertical deflection winding during a trace period of each deflection cycle. The amplifier is switched off by an input waveform to initiate the retrace interval. A voltage developed across the winding to oppose a change in deflection current activates switching means to couple the winding to a second voltage source during retrace. The voltage applied to the winding during retrace is of greater magnitude than the first voltage. The switching means bypasses the winding current away from the main conducting paths of the amplifier during retrace.

Vertical deflection circuit

A power supply which produces a pulsating direct current potential from a first source of alternating current potential and provides a direct current potential to a means for developing a viewable display on a kinescope utilizes a filter network which includes a first inductor. The first inductor provides for a relatively constant level of direct current potential to the means for developing a viewable display with a predetermined range of direct current being supplied to the means for developing a viewable display and a relatively constant level of pulsating direct current potential. A second inductor magnetically coupled to the first inductor and the means for developing a viewable display provides a second alternating current potential greater than a predetermined level to the means for developing a viewable display. The second alternating current potential level decreases to a level below the predetermined level when the inductance of the first inductor decreases to a value less than the predetermined inductance level, thereby rendering the kinescope unviewable.

Power supply for a television receiver

In a deflection system including an oscillator and an amplifier providing scanning current for a deflection winding, a parabolic voltage developed at the deflection winding is superimposed on the oscillator direct current operating voltage in such a proportion that an increased parabolic voltage level, indicative of excessive scanning current from either an overscan or low operating frequency condition, causes the oscillator to operate at a higher frequency which decreases the deflection winding current and therefore the parabolic voltage and thereby permits the use of less expensive circuit components having lower maximum voltage level ratings.

Deflection system with overscan protection

A class D amplifier, suitable for use as a vertical deflection amplifier in a television receiver, includes two transistors coupled to function in a push-pull manner. Two diodes are serially coupled with each other in parallel with the output transistors and are poled to conduct forward current in a direction opposite to the forward current of the two transistors. A junction of the two transistors is coupled to a junction of the two diodes and forms an output terminal to which a deflection winding is coupled. A series of pulses at a first frequency, such as the horizontal deflection frequency or a multiple thereof, are pulse width modulated in accordance with the amplitude of a sawtooth waveform at a second frequency, such as the vertical deflection frequency, in a pulse width modulation stage and are coupled to the input terminals of the two transistors. The two transistors are alternately enabled for conduction by the pulse width modulated signals. During the first half of the vertical scan interval when average deflection current is flowing in a first direction through the deflection winding, the first transistor conducts current in the forward direction and the second transistor and its associated diode conduct current in their reverse and forward directions, respectively. During the second half of vertical scan with the average deflection current flowing in the opposite direction, the second transistor conducts current in its forward direction and the first transistor and its associated diode conduct current in their reverse and forward directions, respectively, for minimizing crossover distortion at the middle of the vertical scan interval.

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Indianapolis, IN, United States of America

John Charles Peer