Radio combined with a digital clock

Claim 1

The combination of a clock having indicating means with phosphorescent indicia for emitting visible light when exposed to ultraviolet radiation, a filter plate disposed in front of said indicating means and which permits the passage therethrough of visible light while blocking the passage of ultraviolet radiation, and a light tube disposed between said indicating means and said filter plate and emitting ultraviolet radiation directed against said indicia, said light tube including a sealed tubular envelope of a material which permits the passage therethrough only of ultraviolet radiation and which has its interior coated with a phosphor material which emits ultraviolet radiation when excited by electrons, first and second main electrodes disposed in the opposite end portions of said envelope and being connected to the opposite sides of an alternating electrical source, first and second auxiliary electrodes respectively connected in parallel with said second and first main electrodes to the respective sides of said alternating source, said first and second auxiliary electrodes being disposed in said envelope adjacent said first and second main electrodes, respectively, so that discharge between said main electrodes is promoted by the generation of ions between each of said main electrodes, alternately, and the adjacent auxiliary electrode, a main resistor connected in series with said main electrodes and said source so that the voltage across said main electrodes is insufficient to cause said discharge therebetween in the absence of said ions generated between each main electrode and the adjacent auxiliary electrode, and first and second auxiliary resistors connected between said first auxiliary electrode and said second main electrode and between said second auxiliary electrode and said first main electrode, respectively, so that said ions generated are sufficient to promote said discharge between the main electrodes, said auxiliary resistors being disposed adjacent the opposite end portions of said tubular envelope for heating the electrodes therein.