PURPOSE: To improve the emission angle (emittance) of thermoelectrons from the cathode of an electron gun for a picture tube, and reduce the discharge frequency between an electron emission layer and first grid.
CONSTITUTION: An electron emission 21, which was being overlaid on a cathode base substance 22 with one layer hitherto, is constituted separately in two layers of a first layer 11 and a second layer 12, and especially the average grain diameters of the electron emissions on the side of the first layer 11 are made smaller than the average grain diameters of the electron emissions on the second layer 12, whereby the flatness of the surface of the electron emission layer is improved. The emission angle (emittance) of thermoelectrons becomes small, and the resolution of a picture tube improves, and also the discharge frequency with a first grid also decreases, and the reliability improves.
KAMATA TOYOICHI
SANO KINJIRO
| JPS603831A | 1985-01-10 |