Centronics Data Computer Corporation

Frederik T Van Namen

Lewis W Bennett

A bidirectional belt-drive for printers and the like comprising a carriage assembly movable across a paper web and supporting a print head mounting bracket. A belt has upper and lower runs extending through guide passageways in the carriage assembly. Independent jam cleat assemblies are normally biased by single spring means to a neutral position so as to be displaced from both runs of the belt. Swingably mounted knurled supporting surfaces cooperate with the jam cleat assemblies to enhance gripping of the fabric belt. Each jam cleat assembly has a pair of cooperating arms whose free ends are arranged to engage one another and extend between the arms of the single torsion spring means. The carriage assembly print head slidably receives the mounting bracket which is urged in the forward direction by bias means and may be adjustably positioned by adjustable cam means to enable the carriage assembly to maintain a fixed position relative to the platen and requiring only movement of the print head mounting bracket. The carriage assembly includes an open frame-shaped casting of a light-weight material significantly reducing inertia as well as the load imposed upon the driving system. Movement of the carriage assembly, regardless of the direction of said movement, drives a ribbon cartridge drive shaft, through a pair of selectively operable clutch assemblies mounted to move with the carriage and rotated by wires encircling the clutch assemblies.

Bi-directional belt drive, print head mounting means and printing plane

A pin-feed tractor assembly for advancing a web of indeterminate length through a printing station and including a timing belt having spaced teeth defining interspersed grooves. The drive sprocket is arranged to engage the notches for moving the belt. Sections of the belt between adjacent notches are rigid while the region of the notches is flexible to permit bending of the belt only at the notches, thereby providing equal stresses in the belt. The outer surface of the belt is provided with feed pins arranged at equi-spaced intervals. The pitch of the belt teeth is one-half the pitch of the perforations in the elongated web which receive the feed pins. The pitch circle of the equi-spaced feed pins is smaller than the pitch circle over the rigid flat portions causing the feed pin to retract somewhat from the web before starting its circular path around the drive sprocket to prevent the web from being damaged or torn. The belt is a molded one-piece member. The design of the tractor assembly is such as to minimize the total number of parts thereby significantly increasing the simplicity of design. In an alternative embodiment, a mechanical contact pair is incorporated to provide paper out and/or paper counting functions. As still another preferred embodiment, optical scanning means arranged within a snap fitting body may be mounted to a tractor assembly to likewise provide paper out and/or line counting functions.

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Londonderry, NH, United States of America

Frederik T Van Namen