A Fast Warm-up Monochrome Picture Tube for Solid-State Receivers

A warm-up time of less than two seconds can be realized with picture tubes employing the described directly heated cathode assembly. Heater power requirements are low; mechanical life reliability has been demonstrated; dynamic life evaluation, while still in progress, appears to be satisfactory. Two different methods of powering the picture tube heater from the deflection circuit have been described. The first method using a link over the flyback transformer does introduce ringing from the flyback high-voltage winding into the video signal. Shielding the link reduces the ringing, but adds stray capacitance to the video circuit. The second method, using the toroidal transformer powered by the horizontal yoke current eliminates the ringing problem and has minimal effect on video bandwidth. The fast warmup characteristics of the picture tube are enhanced by the low impedance source of heater voltage obtained from the toroidal transformer.