Patent ID: 7575392

Claim:
A ground cover laid on a pavement bed, comprising paving stones ( 20 , 44 , 45 , 46 , 48 , 49 ) each having an essentially flat top side ( 23 ), a bottom side ( 24 ), four upright sides, spacers ( 22 ) arranged continuously around the four upright sides ( 25 , 26 , 28 ) in a regular grid pattern ( 39 ), and shifting prevention devices on the four upright sides ( 25 , 26 , 28 ) and the bottom side, wherein: a) the spacers ( 22 ) of one of the paving stones are arranged to engage in an offset manner to the spacers ( 22 ) of a neighboring paving stone; b) the shifting prevention devices on the bottom side ( 24 ) are a plurality of depressions ( 56 ) that interlock with the pavement bed ( 58 ) and that extend continuously from one of the upright sides ( 25 , 26 , 28 ) to another of the upright sides ( 25 , 26 , 28 ); c) the bottom side ( 24 ) has projections between the depressions ( 56 ) extending across the entire bottom side ( 24 ); d) the depression ( 56 ) are arranged parallel to one another and are spaced at equal distances from one another; e) the spacers ( 22 ) have a flange shaped, trapezoidal cross-section and have a constant width ( 33 ) and depth ( 34 ), are arranged in a regular grid pattern, and are spaced at the same intervals on the upright sides ( 25 , 26 , 28 ); and f) the paving stones are laid on the pavement bed in a continuously interlocked manner such that one of the four upright sides of one of the paving stones abuts one of the four upright sides of the neighboring paving stone.