PICTURE DISPLAY APPARATUS

摘要

PURPOSE:To reduce change of focusing condition of flowing electrons due to vertical deflection even in case a flat type display element is used by changing a voltage to be applied to the electrodes of rear side during release of flowing electrons in accordance with vertical deflection of said electrons. CONSTITUTION:It is necessary to eliminate difference of angle of incident electrons to the slit 10 of vertical focusing electrode 3 and uniform the direction in order to eliminate aberration during vertical deflection of flowing electrons and obtain good focusing condition. Therefore, a potential of rear side electrode 1 is deeply biased in the negative direction. Thereby, the flowing electrons in the rear side released from the cathode 2a-2d can be squeezed and the flow of electrons having the uniform vector component to the front side can be input to the slit 10. When considering a picture display element from both application rate of flow of electrons and enhancement of brightness, electrons as many as possible should pass. For this purpose, such both conditions are satisfied by modulating a voltage applied to the electrode 1 in the rear side in accordance with deflection in the vertical direction.