| 摘要 |
Automatic incremental control of the exposure of a photosensitive image-receiving material during contact or projection printing is achieved by the use of a scanning exposing light beam, such as that from a cathode ray tube, wherein both the beam intensity and its rate of deflection can be varied in response to signals derived from a photodetector which views the scanning light after its passage through each incremental area of the transparency being reproduced. Embodiments capable of combined control of the intensity and velocity, or the dwell time, of the scanning light beam are disclosed, together with means for controlling exposure level and contrast. |
