New electronic tube to a screen, in particular of the tube, the tuning indicator

摘要

690,757. Electron beam apparatus. SIEMENS & HALSKE AKT.-GES. Sept. 8, 1950 [Sept. 9, 1949; Dec. 9, 1949; Dec. 9, 1949; Jan. 23, 1949; Feb. 6, 1950; Feb. 10, 1950], No. 22233/50. Class 39(i). An electron valve, for example a tuning indicator valve, comprises an elongated cathode, a luminescent screen anode of elongated form facing the anode to provide a luminous column whose length can be varied, and an elongated non-cylindrical control electrode situated between the cathode and anode and having at least one aperture therein to serve both for the control and for the screening of the electron flow to the anode without the use of additional bunching or deflecting electrodes. In Fig. 1 the cathode 1 is indirectly heated, the control electrode 3 is a diaphragm with a triangular aperture, and the anode is a glass rod 7 provided with a groove 8 in which is disposed a luminescent material; an auxiliary anode comprising the plates 4 and 5 may be provided. In a modification, Fig. 2 (not shown), the electrode 3 is tilted instead of being in a plane parallel to the anode and cathode. In Fig. 3 the control electrode 14 has a rectangular aperture and is curved towards the anode. The control electrode may have two apertures, Fig. 4 (not shown), or a double aperture as in Fig. 5. When this tube is mounted in a receiver it is preferably connected so that when the receiver is off tune the anode shows a continuous line; as the receiver approaches proper tuning the indication breaks into two lines which gradually diminish in length. The cathode 20 may be directly heated and the anode current of the valve stage to be tuned may be carried partly or wholly through the filament; on reaching exact tuning the anode current is reduced, resulting in reduced heater current and consequently a darker indication on the fluorescent screen which reinforces the darkening effect due to the reduced lengths of the lines. The control electrode may be a frame 30, Fig. 7, instead of a diaphragm and screening electrodes at cathode potential may be arranged on either side of the frame, Fig. 8 and 9 (not shown). In another arrangement, Fig 10, the control electrode 48 has a varying depth along its length to give a varying control effect, and the same result may be obtained by using a frame electrode as shown in Fig. 15.