| 摘要 |
PURPOSE:To prevent the burning of a condensing lens and to elongate its life, by providing a screening plate, which screens the laser light beam reflected by a metal mask plate, between the condensing lens and the metal mask plate. CONSTITUTION:In the laser printing device, the screening plate 6 is provided between the condensing lens 1 and the metal mask 4. A through hole 7 is provided in said screening plate 6, and the laser light beam 2 is converged in the inside of said through hole 7. Therefore, the most of the reflected laser light 2' from the metal mask plate 4 is screened by the screening plate 6 and does not reach the condensing lens 1. Therefore, the burning of the condensing lens due to the reflected laser light 2' as experienced in a conventional method can be prevented. As another method, the metal mask plate 4 can be provided so that it is inclined with respect to the optical axis of the laser light beam, not in perpendicular to the optical axis. |
