US Patent 11459809 Hinge

A hinge includes first and second rotary members each rotatably mounted on a base seat about an axis in an axial direction between unfolded and folded positions, and a synchronizing unit including first and second racks which are movably mounted on the base seat in a lateral direction and respectively coupled with the first and second rotary members, and at least one pinion which is interposed between and meshes with the first and second racks to make opposite synchronizing movements of the first and second racks to transmit rotations of the first and second rotary members and the movements of the first and second racks to make opposite synchronizing rotations of the first and second rotary members.