| 摘要 |
PURPOSE:To form a desired grade on a film by arranging a shielding plate with a circular aperture in its center between a light source and film provided with a net- positive pattern plate, and by moving forward and backward this shielding plate to control the quantity of light transmitting through the circular aperture. CONSTITUTION:Inside lamp house 21, lamp 23, condenser lens 24 and milk-white diffusing plate 25 are arranged, and between this lamp house 21 and film 29 provided with net-positive pattern plate 28, stop 26 and shielding plate 27 with a circular aperture are arranged. This shielding pate 27 is able to move forawrd and backward between film 29 and lamp house 21 by movement unit 30. In this constitution, when film 29 is irradiated with light from lamp house 21, shielding plate 27 is made away from film 29 toward lamp house 21, so that a pattern with a grade will be generated on film 29. Further, changing the shape of the aperture provided to shielding plate 27 makes it possible to provide the grading of a dot size. |
