Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Publication of NL251784ApublicationCriticalpatent/NL251784A/xx
H01J1/00—Details of electrodes, of magnetic control means, of screens, or of the mounting or spacing thereof, common to two or more basic types of discharge tubes or lamps
H01J1/02—Main electrodes
H01J1/13—Solid thermionic cathodes
H01J1/20—Cathodes heated indirectly by an electric current; Cathodes heated by electron or ion bombardment