| 摘要 |
516,246. Cathode-ray tubes. TELEFUNKEN GES. FUR DRAHTLOSE TELEGRAPHIE. June 24, 1938, No. 18723. Convention date, June 24, 1937. [Class 39 (i)] The rays from a cathode 1 are directed at an aperture 11 in an electrode 5 which is to be reproduced on the screen, and an electrode 6 following the electrode 5 is given a potential equal to or slightly less than the electrode 5 for the purpose of preventing secondary electrons produced at the aperture 11 from reaching the screen. The electrode 6 is preferably conical with the smaller end adjacent to the aperture 11 and of such a diameter as to accommodate variations of the cross-section of the beam due to modulation. Alternatively the electrode 6- may be composed of a number of apertured diaphragms of increasing diameter, or in the form of a cylinder or an apertured diaphragm. The beam leaving the cathode 1 is first directed under the influence of the field caused by the electrodes 1, 2, 3, on to an aperture 10 and is then focused on to the aperture 11 by the field existing between the electrodes 3, 4 and 5. The electrode 4 may be used to modulate the beam. The main electron lens is formed by the field between the electrodes 7 and 8. |
