Patent GB-808646-A (GB)
Title: Improved lighting fixture
IPC: F21V17/10
Filed: 1956-10-31
Abstract: 808,646. Lighting fittings. WILSON LIGHTING & DISPLAY Ltd., J. A. Oct. 31, 1956 [Nov. 7, 1955], No. 33264/56. Class 75(2) Two or more light diffusers 3 are supported end to end on a lighting fitting 1 by engagement with supports 10 on the fitting 1 in such a manner that longitudinal movement of any one diffuser, relative to the fitting, towards or away from an adjacent diffuser disengages said one diffuser from its support to allow it to swing downwardly, Fig. 9, the spacing between the diffuser ends being sufficient to allow such longitudinal movement and being normally obscured by a flange such as 28a or 28b on the end of each diffuser which overlaps the adjacent diffuser in such a manner that it does not interfere with the longitudinal movement or downward swing. As shown each diffuser 3 comprises arcuate elongated side plates 4a, 4b connected by transverse winged members 5 radiating laterally from a V-sectioned rib 6. The upper edge of each side plate 4a, 4b has a pair of spaced recesses 18 moulded therein each providing an open pocket 17a which receives the cranked end 12a or 12b of a bar 11 fixed transversely across the top of the fitting 1. The bar ends 12a, 12b are bent to extend in opposite directions and each has a terminal ridge 13. That side wall of each pocket 17a, 17b which faces the free end of the associated bar end is slotted at 26 to permit passage of said bar end, on longitudinal movement of the diffuser, into an upwardly closed pocket 23. The slot 26 leaves an upper lip 22 of the sidewall which rests on the associated bar end 12a or 12b when the latter is received in the pocket 23, the ridge 13 of the bar end engaging behind the lip to resist disengagement from the pocket 23. The dimensions, and relative longitudinal position of opposed pockets 17a, 17b, are such that, with the diffuser fully supported with both ends of the two bars 11 engaged in their associated pockets 23, longitudinal movement in one or other direction disengages the diffuser from the bar ends at one or the other side only and allows the diffuser to swing downwardly with the other bar ends acting as pivots. For complete removal of the diffuser, it is then moved in the opposite longitudinal direction to disengage said other bar ends from their pockets. The procedure is reversed for remounting of the diffuser. To obscure the gaps g, Fig. 8, necessary between the ends of adjacent diffusers when in their supported alignment, each diffuser has a pair of flanges 28a, 28b extending respectively from diagonally opposite ends of the sides 4a, 4b, the other end 29 of each side being unflanged. Fig. 8 shows the overlap of the flanges 28a, 28b with the adjoining unflanged side of adjacent diffusers 3, 3<SP>1</SP>, the overlap f being such that the flanges will clear the adjacent diffuser when moved away therefrom to disengage say bar ends 12b. The overlap is increased on mutual approach of the diffusers to disengage bar ends 12a, and to ensure that such overlap does not interfere with the pivoting of the diffuser 3<SP>1</SP> about ends 12b, the unflanged ends 29 of each diffuser is cut away at their upper corners 37, Fig. 1. The rib 6 of each diffuser is extended at each end by flanges 31a, 31b and 31c. 31d respectively, which are relatively positioned to overlap as shown in Figs. 7 and 8, and are gapped near the apex of the rib to permit the swinging movements of each diffuser.