Photocomposition escapement drive system

Claim 1

A photographic type composing apparatus having a collimating lens, means for putting in the focal plane of the collimating lens an image of the character to be projected, an illuminating device to project the images of selected characters forming a line successively through the collimating lens, each character having a predetermined width value and being projected while it is in the projection position, a translating lens combination including a converging lens and a reflector arranged one behind the other to focus the projected light and reflect it through a predetermined angle, a support to hold a sensitized surface in substantial coincidence with the focal plane of the light leaving the lens combination, characterized by an improved means for displacing the lens combination relative to the collimating lens and longitudinally of the surface after each projection by variable distances proportional to the widths of the corresponding characters, comprising, a stepper motor primary drive means, and a mechanical motion reducer system means for dividing a step of said motor into a reduced output motion, wherein the stepper motor has a step movement at least twice the required step size to position the lens combination at all possible required distances and wherein the mechanical motion reducer system is a flexible line driven by a line spool carried by the motor, and the line is reeved around a stationary position turning surface, a similar turning surface carried by the carriage, and extends back toward the stationary turning surface to a anchor point in a block and tackle configuration to reduce the motor output at least by half the length of line taken up in one motor step.