US PATENT SUBCLASS 313 / 591
.~.~ Having cathode heater

Current as of: June, 1999
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313 /   HD   ELECTRIC LAMP AND DISCHARGE DEVICES

567  DF  WITH GAS OR VAPOR {24}
581  DF  .~ Three or more electrode discharge device {9}
591.~.~ Having cathode heater {1}
592  DF  .~.~.~> With control electrode {1}

DEFINITION

Classification: 313/591

Having cathode heater:

(under subclass 581) Subject matter wherein there is a cathode which is electrically heated by the passage of an electrical current through an electrical resistance element which may be the cathode.

SEE OR SEARCH THIS CLASS, SUBCLASS:

337+, for indirectly heated cathodes, per se.

341+, for filament or resistance heated electrodes, per se.

629, for gas or vapor tubes having a resistance heated cathode.