.~.~ Disk seal tube (e.g., lighthouse, pencil tube)
DEFINITION
Classification: 331/98
(under subclass 97) Subject matter wherein the active element comprises an electron tube including an envelope having an axis of symmetry and wherein at least one electrode, usually the control grid of the tube, has an external contact comprising a planar disc or annulus whose center of revolution is on the axis of symmetry of the tube envelope and normal thereto. Examples of such electron tubes are the lighthouse tube and the pencil tube wherein the anode, grid and cathode external contacts are surfaces of revolution about the axis of the tube envelope and are displaced longitudinally there along.
SEE OR SEARCH CLASS
313, Electric Lamp and Discharge Devices,
237+, especially subclasses 249+, for the structure of lighthouse and pencil type space discharge devices.
