DFAA - No Belts

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Pre-existing printers used belts and pulleys to drive the printhead back and forth across the paper. Since belts are difficult to assemble due to their flexibility, a helix drive system and gear was developed for the Proprinter. A double helix screw and a molded nut drive the print head and the ribbon. The helix rotates while the nut moves axially, causing the print head, which is attached to the nut, to traverse a horizontal print line.

The stepper motor which drives the helix assembles with a twist and lock. Ordinarily motors have been mounted with up to 24 screws, nuts, and washers.

A belt design would have required a human assembly step because of its handling complexity. The helix drive, on the other hand, takes into account ease of assembly. This design made it possible to robotically insert the helix with one top down insertion.

Proprinter printhead drive system
The Helix Drive

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Last Updated: October 26, 1998, NEEDS Staff
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