| 摘要 |
PURPOSE:To keep the wall surface temperature of a lamp constant by operating a cooling airflow rate adjusting member for the lamp in accordance with a moving member when a part of this member is moved to change the flow passage constitution. CONSTITUTION:Since an airflow control plate 62, partitioning pieces 64 near the intake part of a lamp cooling fan 10 are close to increase the resistance to air intake and the increase of the flow rate is prevented to prevent the lamp wall surface from being too cooled when a lens attaching plate 61 approaches a lamp 4. When the lens attaching plate 61 is moved in the direction of an arrow (c) away from the lamp 4, the gap between this plate 61 and a spherical mirror attaching plate 60 is extended to reduce the flow rate per unit area in the vicinity of the lamp 4, but partitioning pieces 64 of the control plate 62 are sparse to reduce the resistance to air intake for lamp cooling and the reduction of the flow rate is prevented to prevent the lamp wall surface from being too warmed. Thus, the variance of the flow rate of cooling air to the lamp 4 is prevented when the flow passage is widened or narrowed.
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