US Patent 9326654 Roller brush for surface cleaning robots

A roller brush for a cleaning appliance that includes a brush core defining a longitudinal axis of rotation and three or more dual rows of bristles disposed on and equidistantly spaced along a circumference the brush core. Each dual row of bristles includes a first bristle row of a first bristle composition and having a first height and a second bristle row of a second bristle composition stiffer than the first bristle composition and having a second height. The second bristle row is circumferentially spaced from the first bristle row by a gap less than or equal to 10% of the first height. Also, the first height is less than or equal to 90% of the second height.