Abstract: A display apparatus for displaying pictures virtually instantaneously adopts a direct-heating type cathode of an impregnated structure, and includes a cathode ray tube having a dispenser cathode wherein a cathode material is filled in pores of a porous body and a porous heater is directly connected to the cathode material. A voltage generator of the apparatus produces a first voltage for driving the heater. A video signal supply portion supplies a video signal to the cathode, while a deflector deflects horizontally and vertically an electron beam generated from the cathode to produce a raster by scanning the fluorescent surface of the cathode ray tube. A flyback transformer generates a second voltage to be supplied to the anode and one or more grids of the cathode ray tube using a horizontal deflection output signal supplied from the deflector. With the described arrangement, an electron-emitting velocity of an electron gun reaches its maximum value within about one second after power is applied.