Flat spring drive system and window cover

(57) Indicate the spring driver system (15) of a summary window cover (10, 20), and this spring driver system, Including a flat spring drive (26, 31, 41), the combination of the component of a spring driver system, (1) The band gearing (21) to which the power transfer ratio at the time of opening and closing a cover can be changed, (2) It is chosen from the gear transmission (70) which brings about a fixed power transfer ratio when opening and closing the spur gearing (60) and (3) covers (10, 20) which have various gear sets which bring about friction holding power and a fixed power transfer ratio. With this combination, when opening and closing a cover, spring driving force is obtained by a cover (10, 20) (10), for example, a horizontal スラット cover, a pleat, or the box blind cover (20).