To provide a light source unit capable of cooling a light-transmitting plate from the inside of a reflector while simplifying its explosion-proof construction.
In this light source unit U1, an opening in a reflector R is covered with a light-transmitting plate 20 by fixing the light-transmitting plate 20 to an part of the opening, and thus a structure suitable for explosion protection is obtained. The reflector R is provided with an air inflow part 24A for introducing air into the interior and an air discharge part 24B for discharging the air introduced from the air inflow part 24A into the exterior, and the reflector R and the light-transmitting plate 20 are cooled by the cooperation of the air inflow part 24A with the air discharge part 24B. When the reflector R made of glass and the light-transmitting plate 20 made of glass are appropriately cooled by such a structure, the strength of the reflector R and of the light- transmitting plate 20 is ensured. Even if a luminous tube 1 should rupture, the explosionproof construction can be properly maintained.
ISHIHARA SHOJI
ISHIHARA SHIGEKI
