| 摘要 |
PURPOSE:To obtain a print less in image irregularity at all times by enabling a prism which is provided on the optical axis from a lighting lamp to an image to rotate around the optical axis. CONSTITUTION:A trapezoid prism 16 for illumination light rotation is held on a prism holder 17, which is installed rotatably on a holder 18. When this prism holder 17 is rotated, the prism 16 rotates around the optical axis (e) and illumination light rotates by an angle twice as large as the angle of rotation of the prism 16. The illumination light is therefore directed optionally by rotating the prism 16. When a laterally long image 31b is printed, the prism 16 is so rotated that the filament 1a of the illumination lamp 1 becomes laterally long, and consequently the filament 1a of the illumination lamp 1 also becomes laterally long in a laterally long lighting range; when a longitudinally long image is printed, the filament 1a of the illumination lamp 1a becomes longitudinally long in a longitudinally lighting range, so the print less in light quantity irregularity is obtained.
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