Infrared-ray lamp tube

An infrared-ray lamp tube comprising:

• an elongate tube-shaped housing having an inner space defined therein, wherein the elongate tube-shaped housing have both side open ends;
• an infrared-ray emitting array disposed in the inner space, wherein an infrared-ray emitting array includes a plurality of halogen lamp units spacedly arranged in an array in the inner space in a length direction of the elongate tube-shaped housing;
• a filtering liquid filling the inner space of the elongate tube-shaped housing;
• two plugs respectively fitted into the both side open ends of the elongate tube-shaped housing, and including:
• a first plug having an inlet through which the filtering liquid flows into the inner space;
• and
• a second plug opposite to the first plug and having an outlet through which the filter liquid in the inner space flows out;
• and
• a bubble-discharge guide in the inner space in a position adjacent to the outlet, and including:
• a front surface facing the first plug, and positioned to conceal the outlet when viewed from the first plug;
• an outer circumferential surface spaced apart from an inner surface of the elongate tube-shaped housing with a first gap;
• and
• a rear surface opposite to the front surface, facing the outlet, and spaced apart from an inner wall of the second plug with a second gap being in fluid communication with the first gap such that the filtering liquid in the inner space flows toward the outlet over the front surface through the first pap and the second gap in order.