GB418662A - Improvements in miners' and other portable lamps - Google Patents

Abstract

418,662. Electric lamps. HAILWOOD, E. A., Beacon House, Texas Street, Morley, near Leeds. Jan. 25, 1933, No. 2356. [Class 39 (ii).] A portable electric lamp adapted more particularly for miners' use, is provided with a luminous electric discharge tube as the source of light, the luminous discharge being initiated by connecting the lamp terminals to an electric circuit of comparatively high voltage, after which the terminal connections are transferred to a comparatively low voltage source such as accumulators or a small dynamo driven by compressed air. A transformer, induction coil, or the like may be interposed in the low voltage circuit in order to obtain a voltage sufficient to maintain the glow discharge. The lamp is provided with a switch to enable the change over from the high voltage starting circuit to the comparatively low voltage operating circuit to be effected, and means such as a magnetic lock or sunken terminals may be provided to prevent tampering. A small electric incandescent lamp bulb may be provided as an emergency lamp in the event of the glow discharge lamp failing. In the example the lamp is provided with a switching device comprising an insulating member S mounted transversely within the upper portion of the battery casing, and provided with contacts S<1>, S<2> and S<3>, S' connected to pins S<5>, S<6> adapted to make contact with spring-pressed pins P<1>, P<2> on a high voltage supply plug P when the member S is in its inner position, the terminals N<1>, N<2> of the glow discharge tube N then being in contact with the contact faces S<2>, S<3>. The member S is screw-threaded at its other end to receive a screw-cap T which is rotated to move it longitudinally to withdraw the pins S<5>, S<6> from the plug contacts and bring the contacts S<1>, S<3> on to the accumulator terminals A<1>, A<2>. Further movement of the member S puts the accumulator terminals in circuit with the terminals L', L<2> of an electric incandescent lamp bulb L. A guiding-pin R fixed on the side of the casing engages an apertured lug R<1> on the insulating body S to prevent rotary movement of that member.