(under the class definition) Discharge devices provided with means between the cathode and anode to change the width of the electron stream between the anode and the cathode.
(1) Note. Included in this subclass are discharge devices of the so-called "magic eye" type which have an annular anode coated with fluorescent material surrounding an emissive central cathode and a control electrode for varying the width of the discharge between the cathode and anode so that as the potential of the control electrode varies the width of the nonluminous portion of the anode varies.
SEE OR SEARCH THIS CLASS, SUBCLASS:
293+, and the subclasses specified in the notes thereto, for other discharge devices which have a control grid or other apertured electrode interposed between the cathode and anode, see especially indented subclass 299 where the discharge device is provided with a plurality of control electrodes with the apertures in the different electrodes in alignment (e.g., beam power type tubes).
364+, for cathode-ray tubes provided with means to focus the electrons into a restricted beam and with means for deflecting the beam over the surface of a target. See especially indented subclasses 461+ where the target is a fluorescent or phosphorescent screen.
483+, for other discharge devices provided with fluorescent
