(under subclass 567) Subject matter wherein there are two electrodes and the electrodes and the electrode spacing are so designed that during the operation of the device only the negative or cathode glow portion of the discharge will generate visible light.
SEE OR SEARCH THIS CLASS, SUBCLASS:
615, for a gas or vapor discharge device having a shield between the anode and crater type cathode to control the type and the shape of electrical discharge.
618, for a gas or vapor discharge device having a hollow or crater like cathode to confine the luminous electrical discharge to the interior or hollow of the cathode.
