| 摘要 |
<p>PURPOSE:To prevent an exposure time from being prolonged caused by the effect of the responsiveness of an optical shutter by providing a means which attenuates the prescribed quantity of light between a light source and a photosensitive recording medium in the case that the photosensitive recording medium is exposed according to an image signal impressed on the optical shutter. CONSTITUTION:A device which exposes the photosensitive recording medium 7 according to the image signal impressed on the optical shutter 6 is constituted by providing the light attenuation means 23 which attenuates the prescribed quantity of the light between the light source 3 and the recording medium 7. The light emitted from the light source 3 has wavelength required for exposing the recording medium 7 and it is made incident on the shutter 6 through a condensing means 4 as the almost collimated beam of the light. Then, the shutter 6 is controlled according to the image signal inputted from the outside. The expression of gradation density in the image signal can express 256 gradation and the 256 gradation is realized by the light attenuation means 23 by combining three sheets of density filters having different transmissivity. Besides, the total opening and closing time of a liquid crystal cell required for the gradation is made remarkably short in comparison with conventional one. Thus, the exposure time is not prolonged caused by the effect of the responsiveness of the optical shutter.</p> |
