Patent GB-728848-A (GB)
Title: Improvements in or relating to electric battery torches
IPC: F21L4/00
Filed: 1952-10-21
Abstract: 728,848. Electric torches. FITCH, C. K. Oct. 21, 1953 [Oct. 21, 1952], No. 26452/52. Class 39 (2) [Also in Group V] An electric torch comprises a preformed assemblage of battery and bulb, with electrical connections between them, all embedded in a block of moulded insulating material having at least the portions thereof in front of the bulb transparent, The block of insulating material may be provided with a slot to receive a switch element which bridges a gap in the electric circuit when in a particular position. Preferably, however, the torch has an inertia or gravity operated switch completely embedded within the moulded material; means.may then be provided to lock the switch in an open position or to interrupt the circuit temporarily to prevent the lamp from being lighted during transit, e.g. from the factory. Temporary circuit breaking means may be enclosed in a cavity in the block'or within an embedded container into which the spaced ends of two conductors are introduced, the cavity being partly filled with an electrically conductive material such as Woods metal which can be rendered fluid by the application of heat to the outside of the block, so that by holding the torch in a predetermined position while it is heated, the gap between the ends of the two conductors can be either closed or opened, as desired. Alternatively an inertia or gravity operated switch may be rendered ineffective by arranging in the circuit an auxiliary switch that is controlled by a magnet applied to the exterior of the moulded block, e.g. the auxiliary switch may comprise a screwthreaded spindle attached to an armature which follows the rotation of an external magnet and is moved axially against a fixed contact member. A screw-threaded spindle operated in a similar manner may be moved into the path of a pivoted lever which carries the movable contact or contacts of an inertia switch. In the example, wherein switching is effected directly from the outside of the casing, a unit consisting of a reflector 12 with a bracket 11 soldered at its .rear surface and provided with a central aperture to form a holder for a bulb 10, is suspended in a mould, with the reflector facing downwardly, and a transparent liquid resin is poured into the mould until it flows into and around the back of the reflector to the level of the broken line 14, the mould being shaped to form a cover or lens 15. After the resin has set the assemblage is withdrawn from the mould, a threaded former is screwed into 'holes in a U-shaped extension 13 of the bracket, and the cells and their respective connections to the bulb are assembled as a unit with a lug 16 on one cell in contact with the inner end of the threaded former. The unit is placed within a mould, again with the reflector directed downwardly, and with a glass fibre supporting-sheet wrapped around the assemblage if the electric conductors are not sufficiently rigid to hold the parts in position. The end of the screw-threaded former projects through a wall of the mould. Resin is poured into the mould and, after it has set, the screw-threaded former is removed and a charge of grease is introduced into the bore, after which a hollow screw-threaded metal spindle 21 is inserted. The spindle 21 has a manipulating head 24 whereby the inner end 22 may be screwed into contact with the lug 16 connected to one of the cells to close the bulb circuit. The grease in the screw threads prevents leakage of air or moisture along them and, after the spindle 21 has been screwed home, a closure screw 25 is inserted within its outer end and soldered in position. In a further modification embodying a mercury switch, the moulded body of the casing is provided with a plurality of facets any one of which may be rested upon a support, one particular facet, however, being such that the switch circuit is broken when the torch rests upon it. The resins employed may be thermoplastic, thermosetting, or cold-setting liquid.