High voltage generating circuit

A high voltage generating circuit for generating a dc high voltage to be supplied to an anode of a CRT, comprising:

• a flyback transformer having a primary coil and a secondary coil for providing said dc high voltage;
• a first horizontal deflection circuit for applying a first flyback pulse across said primary coil of said flyback transformer;
• a second horizontal deflection circuit for supplying a second flyback pulse for stabilizing said dc high voltage to lower voltage side of said secondary coil of said flyback transformer;
• a potentiometer having a first terminal coupled to a center tap of said secondary coil of said flyback transformer and a second terminal provided with said second flyback pulse form said second horizontal deflection circuit;
• and
• a smoothing capacitor coupled in parallel with said potentiometer, an output voltage from said potentiometer being provided as a focus controlling voltage.

A high voltage generating circuit for generating a dc high voltage to be supplied to an anode of a CRT, comprising:

• a flyback transformer having a primary coil and a secondary coil for providing said dc high voltage;
• a first horizontal deflection circuit for applying a first flyback pulse across said primary coil of said flyback transformer;
• a second horizontal deflection circuit for supplying a second flyback pulse for stabilizing said dc high voltage to a lower voltage side of said secondary coil of said flyback transformer;
• and
• a diode having a cathode coupled to a terminal at which said first flyback pulse appears in said first horizontal deflection circuit and having an anode coupled to a terminal at which said second flyback pulse appears in said second horizontal deflection circuit, whereby switching operations of said first and second horizontal deflection circuits are performed by a single horizontal output switching element.

A high voltage generating circuit for generating a dc high voltage to be supplied to an anode of a CRT, comprising:

• a flyback transformer having a primary coil and a secondary coil for providing said dc high voltage;
• a first horizontal deflection circuit for applying a first flyback pulse across said primary coil of said flyback transformer;
• a second horizontal deflection circuit for supplying a second flyback pulse to a lower voltage side of said secondary coil of said flyback transformer through a coupling capacitor;
• means for controlling a dc source voltage supplied to said second horizontal deflection circuit in response to an output voltage from said secondary coil of said flyback transformer;
• and
• a current detecting circuit for automatic brightness limiting coupled to a lower voltage side of said secondary coil of said flyback transformer for detecting changes in a secondary current of said flyback transformer.