Fluorescent lamp and a method of making same, and a lighting fixture

A fluorescent lamp comprising:

• a light-transmitting glass tube having a softening temperature of about 685 degrees centigrade or less, not substantially including lead (Pb), and including a stem, having an electrode, arranged at each end of the light-transmitting glass tube, wherein the light-transmitting glass tube includes:
• silicon oxide (SiO2) about 60 to about 75 weight %,
• aluminum oxide (Al2O3) about 1 to about 5 weight %,
• sodium oxide (Na2O) about 1 to about 11 weight %,
• potassium oxide (K2O) about 1 to about 10 weight %,
• lithium oxide (Li2O) 0 to about 3 weight %, wherein the total amount of sodium oxide (Na2O), potassium oxide (K2O), and lithium oxide (Li2O) is about 5 to about 20 weight %,
• calcium oxide (CaO) about 2 to about 5 weight %,
• magnesium oxide (MgO) about 1 to about 3 weight %,
• barium oxide (BaO) about 1 to about 10 weight %,
• strontium oxide (SrO) about 0.5 to about 10 weight %, wherein the total amount of calcium oxide (CaO), magnesium oxide (MgO), barium oxide (BaO), and strontium oxide (SrO) is about 4.5 to about 17 weight %,
• boron oxide (B2O3) 0 to about 3 weight %,
• zinc oxide (ZnO) 0 to about 3 weight %,
• antimony oxide (Sb2O3) about 0.1 to about 0.5 weight %, and
• iron oxide (Fe2O3) about 0.01 to about 0.05 weight %.

A method for manufacturing a fluorescent lamp comprising:

• coating a luminescent compound on the inner surface of a straight glass tube;
• wherein the straight glass tube has a softening temperature of about 685 degrees centigrade or less, does not substantially include lead (Pb), and includes:
• silicon oxide (SiO2) about 60 to about 75 weight %, aluminum oxide (Al2O3) about 1 to about 5 weight %,
• sodium oxide (Na2O) about 1 to about 11 weight %,
• potassium oxide (K2O) about 1 to about 10 weight %,
• lithium oxide (Li2O) 0 to about 3 weight %, wherein the total amount of sodium oxide (Na2O), potassium oxide (K2O), and lithium oxide (Li2O) is about 5 to about 20 weight %,
• calcium oxide (CaO) 0 to about 3 weight %,
• magnesium oxide (MgO) 0 to about 2 weight %,
• barium oxide (BaO) about 1 to about 10 weight %,
• strontium oxide (SrO) about 0.5 to about 10 weight %, wherein the total amount of calcium oxide (CaO), magnesium oxide (MgO), barium oxide (BaO), and strontium oxide (SrO) is about 4.5 to about 16 weight %,
• boron oxide (B2O3) 0 to about 3 weight %,
• zinc oxide (ZnO) 0 to about 3 weight %, and
• antimony oxide (Sb2O3) about 0.1 to about 0.5 weight %;
• baking the coated layer on the straight glass tube at a predetermined temperature to form a phosphor layer;
• sealing each end of the glass tube with a stem having an electrode;
• bending the straight glass tube while heating the straight glass tube at the softening temperature of the glass or more;
• exhausting the glass tube via an exhaust tube and introducing rare gas and mercury (Hg) into the glass tube;
• and
• sealing the exhaust tube.

A lighting fixture comprising:

• a fluorescent lamp comprising:
• a light-transmitting glass tube having a softening temperature of about 685 degrees centigrade or less, not substantially including lead (Pb), and including:
• sodium oxide (Na2O) about 1 to about 11 weight %,
• potassium oxide (K2O) about 1 to about 10 weight %,
• lithium oxide (Li2O) 0 to about 3 weight %, wherein the total amount of sodium oxide (Na2O), potassium oxide (K2O), and lithium oxide (Li2O) is about 5 to about 20 weight %,
• antimony oxide (Sb2O3) about 0.1 to about 0.5 weight %;
• a stem, having an electrode, arranged at each end of the light-transmitting glass tube;
• a body holding the fluorescent lamp;
• and
• a ballast arranged on the body for supplying the electric power to the fluorescent lamp wherein the lamp current density, which is the ratio of the lamp current to the cross-sectional area of the glass tube, is about 200 mA/cm2 or more.