| 摘要 |
<p>A picture display device comprises an evacuated envelope and is provided at a first side with an electroluminescent display screen and at an opposite side with an electron gun (6). Between the electron gun (6) and the display screen, the device comprises deflection means with which an electron beam generated by the electron gun (6) can be deflected during operation. The electron gun (6) has at least an electron beam-generating portion (20) and is provided with a main lens system (40) having a first electrode (41), a final electrode (45) and at least one intermediate electrode (42-44) across which a main lens voltage is gradually applied step-wise during operation so as to form an electron-optical main focusing lens. The gun is further provided with means for presenting a dynamic potential (Vd) to at least an electrode (41) of the main lens system (40), which is the first electrode viewed in the direction of propagation of the electron beam (7-9). For an increased dynamic focusing, a coupling capacitor (50) is arranged at least between said first electrode (41) and the subsequent electrode (42) of the main lens system (40).</p> |
