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 NL40061CpublicationCriticalpatent/NL40061C/xx
H01J17/00—Gas-filled discharge tubes with solid cathode
H01J17/50—Thermionic-cathode tubes
H01J17/52—Thermionic-cathode tubes with one cathode and one anode
H01J17/54—Thermionic-cathode tubes with one cathode and one anode having one or more control electrodes
H01J17/56—Thermionic-cathode tubes with one cathode and one anode having one or more control electrodes for preventing and then permitting ignition, but thereafter having no control