| 摘要 |
PURPOSE:To realize excellent exposing and printing for a long period by providing a pillar part in particular outer diameter and a cathode including the end part formed like a cone in a particular vertical angle in a sealed case in such a way that these are protruded each other, providing a cylindrical recession to the area surrounding the cathode and forming a heat radiating coil to the area located within the recession of pillar part. CONSTITUTION:A cathode 7 is composed of long pillar part 7 with outer diameter D of 1.0-1.5mm. and end part 72 formed like a cone having the vertical angle alpha of 30 deg.-45 deg.. A sealing case 8 consisting of quartz glass is composed of the casing part 81 of light emitting portion at the center and the sealing ports 82A, 82B at both ends, and the end part 72 formed like a cone is provided in such a manner as being protruded to the casing part 81 for light emitting portion. A cylindrical recession 9 with an internal diameter larger than the outer diameter D of the pillar part 71 is provided at the area surrounding the circumference of cathode 7 of sealing part 82A in connection with the internal space of sealing case 8. Moreover, a heat radiation coil 51 which is provided for almost entire part of the area exposed in the case 8 of pillar part 71 is wound around the circumference of pillar part 71 of cathode 7. |
