Abstract: Method of and apparatus for the image-wise exposure of a moving light-sensitive medium by means of a light source and a number of switchable light valves disposed between the medium and the light source, each individual image dot being formed on the light-sensitive medium by actuating sequentially and synchronously with the movement of the light-sensitive medium a number of light valves which extend parallel to the direction of movement of the light-sensitive medium so that each image dot is exposed to light a number of times consecutively so that the speed of image formation increases proportionally to the number of light valves.

Abstract: An exposure system for imagewise exposure of a movable light-sensitive layer, dot by dot along a line on the layer, to an electronically modulated light beam such as that of a laser has a narrow slit disposed near the light-sensitive layer in the path of the light beam, the slit being made with a width less than the dimension at the slit of the light beam in the direction of slit width. In this simple way, the laser beam always describes at least one and the same imaging line relative to the light-sensitive layer, even when beam run-out occurs.

Abstract: Transfer of a powder image from a material carrying the image, such as a photoconductive material utilized for indirect electrophotographic copying, is effected magnetically by employing permanently magnetizable developing powder for forming the image, magnetizing the powder image, and bringing the powder image into contact with a first receiving support made of soft magnetic material so that this support is magnetizable and possesses a substantially uniform magnetic permeability over its whole surface but becomes magnetized so weakly that the powder image after being transferred to the first receiving support can be transferred readily from it, directly or indirectly, to a final receiving support which may be plain copy paper. The magnetizable material of the first receiving support has a coercive force of less than about 90 Oersteds and a relative magnetic permeability of at least 2.