Browse Prior Art Database

Original Publication Date: 1978-Feb-28
Included in the Prior Art Database: 2004-Mar-31

Publishing Venue

Xerox Disclosure Journal


A mechanism for counterbalancing a pivoting copier platen having a non-linear torque deflection curve at its hinge varying with its lifting angle by means of a linear-rate torsion spring. Hinge shaft 2, positioned between shaft supports 3, 13 and attached to platen cover 1, rotates as platen cover 1 is lifted through its rotational angle. Hinge gear 4, positioned on and fixed to hinge shaft 2 and inter-meshed with cain gear 5, rotates in unison with hinge shaft 2 thereby rotating cam gear 5 in an opposite direction. Cam shaft 6, driven by cam gear 5 and supported by bearing block 7, rotates cam 8 in unison with cam gear 5. Tang 9 is an integral extension of the free end of torsion spring 10. It is in contact with cam 8 and is repositioned by the rotation of cam 8. The opposite (fixed) end of spring 10 is secured to shaft 2