Clip fixing for retaining thin film

Retaining the tensioning element for a thin planar plastic film including at least one elongated channel portion having a generally U-shaped cross-section provided with first and second flanks joined by a first core member, an elongated inverted channel member having a generally U-shaped cross-section provided with third and fourth flanks joined by a second core member, said second core member having a bottom surface on the inside of said U-shaped inverted channel member, said inverted channel member being dimensioned to be received within said channel portion, the film being respectively received and pinched between said first and third and second and fourth flanks upon assembly of said inverted channel member with said channel portion, wherein the internal profile of said first flank provides a rounded inwardly-projecting rib means proximate the open side of said channel portion for forming a first rounded knuckle surface means and the external profile of said third flank provides a groove means proximate said second core member for forming a second rounded knuckle surface means complementary in shape to said first rounded knuckle surface means for sliding on film extending across said first rounde knuckle surface means and thereby pivoting said channel member thereon during assembly of said channel members to pinch said film therebetween, and wherein said second flank exhibits a cross-section of internal profile which includes an insertion ramp sloping inwardly from an open side of said U-shaped channel portion followed by a curved locking groove proximate said first core member and said fourth flank exhibits a cross-section of external profile which includes an elongated portion extending laterally away from said second core member, said elongated portion having at the outer end thereof, proximate the open side of said inverted channel member, a locking-rib means protruding laterally outwardly from said fourth flank for engaging said locking groove, said locking rib being substantially laterally spaced from the bottom surface of said second core a distance at least as great as the thickenss of the second core, said locking-rib means and said locking groove being complementary one to the other, with said locking-rib means having the function of pinching said film between its surface and said insertion ramp during assembly of said channel members, and between its surface and said locking-groove surface once said channel members are assembled, wherein when said channel portion and said inverted channel member are fully engaged, with ends of said core of said inverted channel member being in an approximately horizontal attitude, said knuckle surface means of said inverted channel member is above the locking-rib means of said inverted channel member with said knuckle surface means being proximate said core of said inverted channel, but said locking-rib means being substantially spaced from said core;

• said retaining and tensioning element further comprising a sunlight-radiation shielding member attached to said inverted channel member at said second core member, said sunlight-radiation shielding member extending laterally outwardly, significantly beyond all points at which said plastic film contacts said first flank to thereby prevent direct sunlight from falling on all said points at which said plastic film contacts said first flank.