In one aspect, the present invention provides a filter cleaning mechanism comprising: a filter material (37) for filtering out dust and dirt particles from air passing therethrough; a frame (32, 34, 35, 38, 39) for supporting said filter material (37); devices (31, 296; 25a, 25b, 25c, 25d) for mechanically agitating said filter material to dislodge dust and dirt particles therefrom; wherein the devices for mechanically agitating said filter material comprises elements (31, 296; 25a, 25b, 25c, 25d) for deforming said frame within its elastic limit and elements (31, 296; 25a, 25b, 25c, 25d) for rapidly releasing said frame from said deformation to cause said frame to relax to an undeformed state. The present invention also provides a hand-holdable vacuum cleaner comprising such a filter cleaning mechanism, as well as a method of cleaning a filter assembly (30) comprising a filter material (37) and a frame (32, 34, 35, 38, 39) for supporting said filter material (37), wherein the method comprises the steps of deforming the frame within its elastic limit and rapidly releasing the frame from said deformation, thereby causing the frame to relax to an undeformed state.