US Patent 7373675 Convertible sofa bed

Disclosed is a convertible sofa bed including a seat frame, a back frame, a support structure, a first and second linkage assembly pivotally coupling the seat frame to the back frame pivotally coupling the seat frame to the support structure and pivotally coupling the back frame to the support structure, and an electrical drive assembly coupled to the first and second linkage assemblies. The electrical drive assembly includes a motor mounted to the support structure, a first and second cable drive rotatably coupled to and extending from the motor, first and second threaded drive screws having an external thread, and first and second right angle gear boxes mounted to first and second aft portions of the support structure. The electrical drive assembly also includes first and second drive nut assemblies mounted to respective first and second linkage assemblies and respective threaded drive screws.