PURPOSE: To improve color rendition of a high tension mercury-arc lamp having an external tube coated with red fluorescent film, by prescribing the shape of a luminous tube and the amount of mercury and cadmium or zinc charged.
CONSTITUTION: An external tube 1 of a fluorescent, high-tension mercury-arc lamp with a rated output of 400W is coated with a luminous film 3 containing red fluorescent matter which provides the maximum fluorescence within a range of wavelength from 610W630nm. A luminous tube 4 is charged with Hg and Cd or Zn. The shape of the luminous tube 4 and the amount of each metal charged are prescribed to satisfy expressions 1W5, where D represents the inner diameter of the luminous tube 4, la the length between electrodes 6, 7, le the length (in cm) from the electrode 6 to seal 13, and mHg, mCd and mZn the amount (mg/cc) of metal charged per unit volume of the luminous tube. The vapor discharge of mercury and other metal added can greatly improve color rendition of the lamp.
MURAKAMI KATSUO
KODAMA HITOSHI
ORIGASA SHIYOUJI
