GB1354315A - Fluorescent lamp - Google Patents

Abstract

1354315 Uses of luminescence MATSUSHITA ELECTRONICS CORP 2 June 1971 [12 June 1970] 18634/71 Heading C4S A low pressure fluorescent lamp comprises a glass tube, a pair of spaced electrodes, Hg and an inert gas, and a blended phosphor layer (as herein defined) containing a magnesium-arsenate phosphor comprising Mn in a ratio between 0À02 and 0À2 grm. atm. : 6 mols of magnesium oxide. "Blended phosphor layer" is defined as a layer of phosphors emitting a spectrum with colour rendering value Ra > 95 and closely resembling natural daylight. The phosphor may be magnesium halosulph-arsenate and the blended layer may further include magnesium tungstate, tin activated strontium magnesium orthophosphate and antimony and manganese activated calcium halophosphate, e.g in relative parts by wt, 4, 2À5 and 1À5, chemical formulae being given, with 0À65 parts of basic magnesium halosulph-arsenate phosphor containing 0À05 gram atoms of Mn per 6 mols of magnesium oxide. The phosphors may be applied as a slurry. The ratio of light emission energy of wavelength less than 450 nm. against the total may be <16%. The lamps may be used in museums or art galleries or for inspecting colourprinted matter, a lamp of 5000‹ K. colour temperature and C.I.E. colour rendering value of 90 to 92 being insufficient for these viewing purposes. High colour rendering lamp (e.g. >95, such as 97) as above absorb radiation <450 nm. and high reflectance for >450 nm., colour rendering normally being lowered by the 435À8 nm. Hg line emission. Emission spectrums may be as in Fig. 2 (not shown).