Patent GB-904756-A (GB)
Title: Improvements in or relating to electric lighting fittings
Inventor: BEGGS STANLEY SUTTON
IPC: F21S8/00
Filed: 1960-06-22
Abstract: 904,756. Electric light fittings. GENERAL ELECTRIC CO. Ltd. June 22, 1961 [June 22, 1960], No. 21871/60. Class 75 (4). In a lamp fitting comprising a lower troughshaped transparent or translucent portion in which two or more electric lamps are wholly or mainly disposed, a wholly or mainly opaque upper portion and refractor elements arranged to concentrate the emergent light about either a single direction or two opposed directions of peak intensity lying at an angle between 10 and 30 degrees below the horizontal, the underside of the upper portion is formed with or carries a diffusely reflecting surface and at least one of the lamps is a reflector lamp with its direction of maximum light intensity inclined above the horizontal. The reflector lamp may be a filament lamp silvered or aluminized over part of the internal surface or a low-pressure mercury vapour fluorescent discharge lamp, the inside of the envelope of which has been coated over two-thirds of the circumference, before the application of the fluorescent coating, with a material of high reflectivity such as titanium dioxide leaving a strap whose width is approximately one-third of the circumference unobscured along the length of the lamp. All the lamps used in the fitting may be reflector lamps. In one form, two fluorescent reflector discharge lamps 9, 10, Fig. 1, are arranged on opposite sides of the central plane of the fitting with their light emissive portions directed upwards and outwards towards refractor plates 3, 4 on the sides of the trough. The canopy is slightly concave downwards and has a stove enamelled white surface 2 forming a diffusing reflector. The plates 3, 4 are shallower than the depth of the trough leaving clear windows 5, 6 below and 7, 8 above them. In one modification a third lamp is arranged on the central plane of the fitting with its bottom level with the upper edges of the refractor plates and its direction of maximum light emission vertically upwards. Flat strips of reflecting material may be mounted below the level of the surface 2 so placed that light incident on them is reflected through the windows 7, 8. Alternatively pairs of reflectors of inverted V-form may be used so that part of the light is directed on to the refractor plates. In a further modification, two additional lamps 18, 19 are arranged on opposite sides of the central plane of the fitting so that their maximum light emission is directed partly on to the windows 7, 8 and partly on to the refractor plates 3, 4. Alternatively, the maximum emission from lamp 18 may be directed on to window 8 and refractor plate 4 and that from lamp 19 on to window 7 and refractor plate 3. In a further modification the lamps 9, 10 are replaced by a single lamp 21, Fig. 8, with its direction of maximum emission vertically upwards, a lamp 22 also with its direction of maximum emission vertically upwards being mounted in the central plate above the top edges of the refractors 3, 4. Further lamps 23, 24 on opposite sides of the central plane and directing light on to the windows 7, 8 and refractor plates 3, 4 may be included either above or below the lamp 22. The lamp 22 may in this case be omitted. The refractor plates 3, 4 may be of the form described in Specification 687,140.