Abstract Luminous flux and luminous efficiency of a 40 watt fluorescent lamp comprising a ballast specified by the I.E.C. Publication 82 (covering Ballast for fluorescent lamps) is greatly improved by employing an improved tube characterized by: HAVING THE NOMINAL TUBE LENGTH OF 1,200 MM AND THE INNER DIAMETER OF 20 MM TO 25 MM, PROVIDED INSIDE AT EACH END OF THE TUBE WITH AN ELECTRODE E having the length l of 15 mm to 55 mm inward (, from the end face of each cap C as measured as shown in FIG. 2,) and containing mixed rare gas inside the tube, the rare gas having composition ratio represented by any point within a diagonal region defined by connecting the following points (a) to (e) and (a) with straight lines in the following order, on a trilinear chart for xenon, krypton and argon mixture: A.Xe: 1%, Kr: 0%, A: 99% b. Xe: 15%, Kr: 0%, A: 85% c.Xe: 15%, Kr: 65%, A: 20% d.Xe: 0%, Kr: 80%, A: 20% e.Xe: 0%, Kr: 5% A: 95% the pressure of the mixed gas being between 1.0 mmHg and 3.5 mmHg at the temperature of 20*C.
A fluorescent lamp according to claim 1, wherein the mixed rare gas consists of krypton and argon.
Claim 2
Dependent Claim
17 words
A fluorescent lamp according to claim 1, wherein the mixed rare gas consists of xenon and argon.
Claim 3
Dependent Claim
217 words
A fluorescent tube for use in a fluorescent lamp having a fitting and a ballast for a standard 40 watt fluorescent tube, said fluorescent tube comprising a tubular glass bulb the inner wall of which is coated with a fluorescent layer, one cap with connecting pins on each end of said bulb, the tube having a length of approximately 1,200 mm, one electrode on each end of the glass bulb, enclosed mixed rare gas and mercury inside the bulb, said glass bulb having an inner diameter of between 20 and 25 mm, each electrode having a length of between 15 and 55 mm as measured from the end face of the cap to a coil of the electrode, the enclosed mixed rare gas having a composition ratio represented by any point within a diagonal region defined by connecting the following points (a), (b), (c), (d), (e), and (a) with straight lines in this order on a trilinear chart for xenon, krypton and argon mixture: a. Xe: 1%, Kr: 0% A: 99% b. Xe: 15%, Kr: 0% A: 85% c. Xe: 15%, Kr: 65% A: 20% d. Xe: 0%, Kr: 80% A: 20% e. Xe: 0%, Kr: 5% A: 95% the pressure of the mixed gas being between 1.0 mmHg and 3.5 mmHg at a temperature of 20*C.