Patent ID: 6840914

Claim:
A unit-type roller drive device of a size to fit within a chair back rest portion of a chair with protruding massaging ball rollers for engaging the back of a human user's body for motor-driven roller massage actions, said chair back being separate from an associated chair seat, comprising: a frame having left and right sides extending longitudinally between upper and lower ends and a frame thickness, a base portion, left and right edge portions standing upright from the left and right sides of the base portion to bound a space corresponding with said frame thickness between said upper and lower ends; a longitudinal guide slit provided in each of the left and right edge portions; upper and lower shafts each having a gear respectively mounted to the upper and lower ends of the frame; left and right roller chains respectively mounted on each side of said frame in a ring shape around the upper and lower shafts and meshing with said gears; a shaft bushing mounted to each roller chain and carrying said massaging ball rollers, the left and right ends of said shaft bushings including guide rollers mounted in said guide slits for guided movement along the slits; a drive motor mounted to said frame operably connected to said gears to move said roller chains and massaging ball rollers between said upper and lower ends of said frame; wherein said guide slits and said roller chains are substantially aligned within the thickness of said frame when viewed in longitudinal section, and said gears, roller chains and drive motor are contained within said space corresponding with said frame thickness to provide a compact device that may be incorporated in a chair back with said massaging ball rollers extending beyond said space corresponding with said frame thickness to engage said user's back.