Sliding film valve driven at edge

A valve including a film (24) having edges and a plurality of openings (26) disposed between the edges is supported by the housing (20) of an automotive a heating, ventilation and air conditioning system to control the flow of air blown into the passenger compartment. The film (24) has recesses (28) along both edges. The film is reciprocated along the curved path by a first pair of sprockets (30) supported on a shaft (36) and presenting first axial teeth (32) engaging the recesses (28) along the edges of the film (24) (Figures 3-5), or a second pair of sprockets (40) having first radial teeth (42) engaging the recesses (28) in the edges of the film (24) and driven from the shaft (36) by bevel gears (46) (Figures 5-8), or third pair of sprockets (48) having second radial teeth (50) engaging the recesses (28) in the edges of the film (24) and driven by a spur (54) (Figure 9), or by the spur (54) directly engaging the recesses (28) in the edges of the film (24) (Figure 10).