| 摘要 |
The light-sensitive layer of a printing plate is charged to a given surface potential which is measured by means of a stationary or moving potential detector. The potential ratio, which changes during the exposure, is continuously compared with a given set value, and the exposure is terminated when the changing potential ratio is in agreement with the given set value. The measurement of the surface potential and of the potential ratio is carried out in a bright area of the light-sensitive layer, which area is located outside the area of the latent electrostatic image. The potential detector may be connected via a signal converter and an amplifier to a microprocessor control which actuates a shutter via a digital output. In the microprocessor, a program for controlling a corona electrode and a developing electrode is stored, which program actuates the corona control and the developing electrode control via a digital/analog output and high-voltage amplifiers. |
