Screw-based incandescent lamp type fluorescent lamp

A screw-based incandescent lamp type fluorescent lamp comprising:

• a luminous tube bent to define a vacant space therein;
• an operating member including a ballast for said tube, the ballast disposed in said vacant space;
• a holder having an opening facing said ballast at a given distance therefrom and holding said tube and ballast;
• a base body supporting said holder and having a flange section in which a plurality of upper ventilation holes are formed;
• a light transmitting bottom envelope having an end edge attached to the peripheral edge of the flange section of said base body and surrounding said tube, at least one lower ventilation opening with an opening area larger than 0.2826 cm.sup.2 and smaller than the total area of said upper ventilation holes being formed in the bottom of said envelope;
• and
• a screw base disposed on the top portion of said base body and electrically connected with said tube and said operating member,
• whereby air introduced from said lower ventilation opening into said light transmitting bottom envelope will flow along the outer peripheral surfaces of said ballast and said tube and be discharged from said upper ventilation holes to the outside via the opening of said holder.