Patent GB-788216-A (GB)
Title: Improvements relating to electric torches
IPC: F21L4/00
Filed: 1956-04-04
Abstract: 788,216. Electric torches. LAMBERT, R. B. April 4, 1956 [April 20, 1955]. No. 10341/56. Class 39(2) The switching means for an electric torch provided with a tubular metal casing 1 comprises a conducting strip 30 which is located within the casing and has a part 36 biased to protrude outwardly through an aperture 37 in the casing and movable into and out of contact with the casing to make and break the circuit, such movements being controlled by a non-conductive switching ring 39 which is slidable axially upon the casing and over the aperture in engagement with the conducting strip 30. The strip 30, made of resilient metal, is sandwiched for most of its length between two wider insulating-strips 31, 32 to which it is secured by an eyelet 33, the insulating strips being themselves secured to the casing by rivets at opposite sides of the conducting strip. The front end of the conducting strip 30 bears against the rear surface of a metal shell 24 on the rear surface of a plastic reflector 25, whilst its rear end, which is in the form of an outwardly convex lug 36, is sprung outwardly through a longitudinal slot 37 in the casing 1. The casing metal at the rear end of the slot 37 is bent inwardly to provide a contact surface 38 from which the lug 36 is normally clear. The convex surface of the lug 36 is engaged within a recess 40 provided in the inner periphery of the switching ring 39, which is made of plastic material and corrugated externally, the rear end 41 of the recess 40 being bevelled so that it operates to push the lug 36 downwardly when the ring 39 is pushed forwardly on the casing. The ring 39 is located positively in the "on" and "off" positions by a locking-strip 50 secured to the casing 1 diametrically opposite to the strip 30 and formed with ribs 52, 53 at its front and rear ends respectively, which project through slots in the casing. The front rib 52 is received within an internal recess 56 in the ring 39. and the rear rib 53 is engaged alternatively in one of two notches 57, 58, corresponding respectively with the "on" and "off" switching-positions of ring 39. Rearward movement of the ring is limited and its unintentional withdrawal from the casing 1 prevented by the front rib 52 abutting against the front end of the recess 56. The rib 52 may be depressed into the adjacent slot 54 in the casing by providing the recess 56 with a bevelled longitudinal edge, which bears upon the rib when the ring is rotated clockwise. The ring can then be withdrawn axially. A similar bevelled longitudinal edge may be provided along the slot 40 associated with switching-lug 36. Alternatively, Fig. 10 (not shown), the locking-rib 52 may be disengaged from the recess 56 in the ring by providing the latter with a radial aperture through which a tool may be pushed on to the rib, so that the ring may be withdrawn without initial rotary movement. In a modification switching "on" is effected by moving the ring 39 rearwardly upon the casing 1, the operative bevelled edge of the recess 40 being at the forward end thereof (as alternative to the operative rear edge 41 in Fig. 2). In a further modification, Fig. 15, the contact-making end of the strip adjacent to the lug 36 lies within the casing 1 and is biased nutwardly against an overhanging tongue or projection 70 forming part of the casing. The lamp is switched off by sliding the ring 39 rearwardly from the position shown. In the example the cap of the bulb 5, Fig. 2, is a push fit within a metal sleeve 6 provided with a front end flange 7 whereby it is held between the front edge of an insulating socket 20 and an inturned flange 22 on a metal sleeve 23 into which socket 20 is screwed from the rear. The sleeve 23 is a push fit into the metal shell 24 behind the plastic reflector 25. The centre contact 8 of the bulb bears against a conical coil spring 9 formed with a flat spiral base 9a in abutment with a plunger 10 against which the central terminal of the cell 11a is pressed by a spring located between the bottom cell and the rear end of the casing.