Process and apparatus for the electro-photographic development of electron-radiographic sheets

The degree of development of an electron-radiographic sheet is controlled by measuring the current flowing between two plate electrodes immersed in the developer liquid with the sheet; development is terminated when the current flow, which falls exponentially with time, reaches a preset value. Development is initiated by introducing developer liquid quickly into a container in which the sheet and electrodes are located and development is terminated by removing the liquid quickly. An electrical control circuit effects the termination of development when the actual current reaches the preset values, the relative current values being monitored continuously by means of a comparator circuit. (author)