US Patent 10383422 Hair care device

An air outlet grill for use on a hair care device comprises a plurality of concentric and tilted flow guide surfaces (2), a cross section of the flow guide surfaces (2) having a curved shape that diverges in an air flow direction. Preferably, tilt angles between the flow guide surfaces (2) are designed such that an air inlet area of the air outlet grill is larger than an air outlet area of the air outlet grill, so as to increase air speed. Preferably, a middle flow guide surface has a smaller height compared to at least one other flow guide surface, so as to increase an area for air to pass through at a middle part of the air outlet grill. Preferably, a leading edge of at least one of the flow guide surfaces (2) is tangent to the air flow direction while a trailing edge of the flow guide surfaces diverges from the air flow direction. Preferably, a cross-section profile of at least one of the flow guide surfaces (2) is airfoil shaped such that a thickness of the leading edge is smaller than a thickness of the trailing edge in the air flow direction.