Patent ID: 7717156

Claim:
A device for creating an angular biasing force for a roller tube of a security shade, which roller tube is mounted to a fixed structure of a vehicle, said device comprising a single shaft attached to said fixed structure of the vehicle and a plurality of independent modular force units having substantially a same size and shape that are positioned on said single shaft, a plurality of said force units positioned inside of a cavity of said roller tube, each of said force units including a housing and a torsion spring, said housing of a plurality of said force units having substantially a same size and shape, said housing of each of said force units designed to be inserted onto one end of said single shaft and slidably positioned along a longitudinal length said single shaft, said housing of each of said force units at least partially encircling said torsion spring, said single shaft secured to said fixed structure such that said single shaft does not rotate relative to said fixed structure, said torsion spring in each of said force units designed to exert a biasing force between said fixed structure and said roller tube, each of said torsion springs having a first inner end slidably connected said single shaft and a second outer end connected to said housing of said force unit, each of said housings rotatably positioned on said single shaft, said cavity of said roller tube including an inner surface, said inner surface designed to engage an outer surface of said housing of a plurality of said force units, said roller tube including a fastener designed to secure said roller tube to said housing of said plurality of said force units, said housing of said force units including an outer surface, at least one of said housings includes a recessed surface in said outer surface that is positioned adjacent to said housing slot in said housing, at least a portion of said second end of at least one of said torsion springs is positioned in said recessed surface.